Patent Publication Number: US-11642125-B2

Title: Robotic surgical system including a user interface and a control circuit

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application claiming priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 16/919,319, entitled SURGICAL INSTRUMENT WITH MULTIPLE PROGRAM RESPONSES DURING A FIRING MOTION, filed Jul. 2, 2020, now U.S. Patent Application Publication No. 2021/0085316, which is a continuation application claiming priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 15/130,566, entitled SURGICAL INSTRUMENT WITH MULTIPLE PROGRAM RESPONSES DURING A FIRING MOTION, filed Apr. 15, 2016, which issued on Nov. 10, 2020 as U.S. Pat. No. 10,828,028, the entire disclosures of which are hereby incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to surgical instruments and, in various circumstances, to surgical stapling and cutting instruments and staple cartridges therefor that are designed to staple and cut tissue. 
     BACKGROUND 
     In a motorized surgical stapling and cutting instrument it would be helpful to have variable control program responses (pause, slow down, speed up, backup and re-advance, and stop) depending on how fast the load is increasing or decreasing (slope) as it approaches predefined staged thresholds (load, current, pressure, velocity). While several devices have been made and used, it is believed that no one prior to the inventors has made or used the device described in the appended claims. 
     BRIEF SUMMARY 
     In some aspects, a surgical instrument is provided. The surgical instrument comprises an elongated channel configured to support a staple cartridge; an anvil pivotably connected to the elongated channel; a closure tube mechanically coupled to the anvil; an electric motor; and a control circuit electrically connected to the electric motor, wherein the control circuit is configured to change a closing motion of the surgical instrument at least two different ways based on the closing force. 
     In various embodiments, a robotic surgical system for deploying staples from a staple cartridge into tissue is disclosed. The surgical robotic system comprises an end effector, a drive system, a user interface, and a control circuit. The end effector is configured to receive the staple cartridge. The end effector comprises a first jaw and a second jaw movable relative to the first jaw from an open configuration toward a closed configuration. The drive system is configured to effect a motion at the end effector. The drive system comprises a motor and a drive member operably coupled to the motor. The control circuit is communicably coupled to the motor and the user interface. The control circuit is configured to activate the drive system to effect the motion at the end effector, monitor a current draw of the motor, pause the drive system intermediate the effected motion at the end effector based on the current draw of the motor, restart the drive system to continue the effected motion at the end effector, and cause the user interface to provide feedback to a user. 
     In various embodiments, a robotic surgical system for deploying staples from a staple cartridge into tissue is disclosed. The surgical robotic system comprises an end effector configured to receive the staple cartridge, a drive system, a user interface, and a control circuit. The end effector comprises a first jaw and a second jaw movable relative to the first jaw from an open configuration toward a closed configuration. The drive system comprises a motor and a drive member operably coupled to the motor. The drive member is advanceable by the motor to effect a motion at the end effector. The control circuit is communicably coupled to the motor and the user interface. The control circuit is configured to activate the motor to effect the motion at the end effector, monitor a parameter indicative of a compression of the tissue between the first jaw and the second jaw, automatically stop the advancement of the drive member based on the parameter, automatically resume the advancement of the drive member, and cause the user interface to provide feedback to a user. 
     In various embodiments, A robotic surgical system for deploying staples from a staple cartridge into tissue is disclosed. The surgical robotic system comprises an end effector configured to receive the staple cartridge, a drive system, a user interface, and a control circuit. The end effector comprises a first jaw and a second jaw movable relative to the first jaw from an open configuration toward a closed configuration. The drive system comprises a motor and a drive member operably coupled to the motor. The drive member is advanceable by the motor to effect a firing motion at the end effector to deploy the staples from the staple cartridge. The control circuit is communicably coupled to the motor and the user interface. The control circuit is configured to activate the motor to effect the firing motion at the end effector to initiate the deployment of staples from the staple cartridge, monitor a motor parameter indicative of a compression of the tissue between the first jaw and the second jaw during the deployment of the staples, pause the motor intermediate the effected firing motion at the end effector based on the motor parameter to pause the deployment of the staples, restart the motor to continue the effected firing motion at the end effector based on the motor parameter to continue the deployment of the staples, and cause the user interface to provide feedback to a user. 
     The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects and features described above, further aspects and features will become apparent by reference to the drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of the aspects described herein are set forth with particularity in the appended claims. The aspects, however, both as to organization and methods of operation may be better understood by reference to the following description, taken in conjunction with the accompanying drawings as follows. 
         FIG.  1    is a perspective view of a surgical instrument that has an interchangeable shaft assembly operably coupled thereto in accordance with one or more aspects of the present disclosure. 
         FIG.  2    is an exploded assembly view of the interchangeable shaft assembly and surgical instrument of  FIG.  1    in accordance with one or more aspects of the present disclosure. 
         FIG.  3    is another exploded assembly view showing portions of the interchangeable shaft assembly and surgical instrument of  FIGS.  1  and  2    in accordance with one or more aspects of the present disclosure. 
         FIG.  4    is an exploded assembly view of a portion of the surgical instrument of  FIGS.  1 - 3    in accordance with one or more aspects of the present disclosure. 
         FIG.  5    is a cross-sectional side view of a portion of the surgical instrument of  FIG.  4    with the firing trigger in a fully actuated position in accordance with one or more aspects of the present disclosure. 
         FIG.  6    is another cross-sectional view of a portion of the surgical instrument of  FIG.  5    with the firing trigger in an unactuated position in accordance with one or more aspects of the present disclosure. 
         FIG.  7    is another exploded assembly view of portions of the interchangeable shaft assembly of  FIG.  7    in accordance with one or more aspects of the present disclosure. 
         FIG.  8    is a cross-sectional view of a portion of the interchangeable shaft assembly of  FIGS.  7 - 9   , in accordance with one or more aspects of the present disclosure. 
         FIG.  9    is another perspective view of the portion of an interchangeable shaft assembly with the switch drum mounted thereon in accordance with one or more aspects of the present disclosure. 
         FIG.  10    is a perspective view of a portion of the interchangeable shaft assembly of  FIG.  11    operably coupled to a portion of the surgical instrument of  FIG.  1    illustrated with the closure trigger thereof in an unactuated position in accordance with one or more aspects of the present disclosure. 
         FIG.  11    is a right side elevational view of the interchangeable shaft assembly and surgical instrument of  FIG.  10    in accordance with one or more aspects of the present disclosure. 
         FIG.  12    is a perspective view of a portion of the interchangeable shaft assembly of  FIG.  11    operably coupled to a portion of the surgical instrument of  FIG.  1    illustrated with the closure trigger thereof in an actuated position and a firing trigger thereof in an unactuated position in accordance with one or more aspects of the present disclosure. 
         FIG.  13    is a right side elevational view of the interchangeable shaft assembly operably coupled to a portion of the surgical instrument of  FIG.  1    illustrated with the closure trigger thereof in an actuated position and the firing trigger thereof in an actuated position in accordance with one or more aspects of the present disclosure. 
         FIG.  14    is an exploded view of one aspect of an end effector of the surgical instrument of  FIG.  1    in accordance with one or more aspects of the present disclosure. 
         FIG.  15    is a schematic of a system for powering down an electrical connector of a surgical instrument handle when a shaft assembly is not coupled thereto in accordance with one or more aspects of the present disclosure. 
         FIGS.  16 A- 16 B  is a circuit diagram of the surgical instrument of  FIG.  1    spanning two drawings sheets in accordance with one or more aspects of the present disclosure 
         FIGS.  17 A- 17 B  is a circuit diagram of the surgical instrument of  FIG.  1    in accordance with one or more aspects of the present disclosure. 
         FIG.  18    is a block diagram the surgical instrument of  FIG.  1    illustrating interfaces between the handle assembly and the power assembly and between the handle assembly and the interchangeable shaft assembly in accordance with one or more aspects of the present disclosure. 
         FIG.  19    illustrates a logic diagram of a system for evaluating sharpness of a cutting edge of a surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  20    illustrates a logic diagram of a system for determining the forces applied against a cutting edge of a surgical instrument by a sharpness testing member at various sharpness levels in accordance with one or more aspects of the present disclosure. 
         FIG.  21    illustrates one aspect of a process for adapting operations of a surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  22 A  depicts an example end-effector of a medical device surrounding tissue in accordance with one or more aspects of the present disclosure. 
         FIG.  22 B  depicts an example end-effector of a medical device compressing tissue in accordance with one or more aspects of the present disclosure. 
         FIG.  23 A  depicts example forces exerted by an end-effector of a medical device compressing tissue in accordance with one or more aspects of the present disclosure. 
         FIG.  23 B  also depicts example forces exerted by an end-effector of a medical device compressing tissue in accordance with one or more aspects of the present disclosure. 
         FIG.  24    depicts an example tissue compression sensor system in accordance with one or more aspects of the present disclosure. 
         FIG.  25    also depicts an example tissue compression sensor system in accordance with one or more aspects of the present disclosure. 
         FIG.  26    also depicts an example tissue compression sensor system in accordance with one or more aspects of the present disclosure. 
         FIG.  27    depicts an example end-effector channel frame in accordance with one or more aspects of the present disclosure. 
         FIG.  28    depicts an example end-effector in accordance with one or more aspects of the present disclosure. 
         FIG.  29    also depicts an example end-effector channel frame in accordance with one or more aspects of the present disclosure. 
         FIG.  30    also depicts an example end-effector channel frame in accordance with one or more aspects of the present disclosure. 
         FIG.  31    also depicts an example end-effector channel frame in accordance with one or more aspects of the present disclosure. 
         FIG.  32    depicts an example electrode in accordance with one or more aspects of the present disclosure. 
         FIG.  33    depicts an example electrode wiring system in accordance with one or more aspects of the present disclosure. 
         FIG.  34    also depicts an example end-effector channel frame in accordance with one or more aspects of the present disclosure. 
         FIG.  35    is an example circuit diagram in accordance with one or more aspects of the present disclosure. 
         FIG.  36    is also an example circuit diagram in accordance with one or more aspects of the present disclosure. 
         FIG.  37    is also an example circuit diagram in accordance with one or more aspects of the present disclosure. 
         FIG.  38    is a perspective view of a surgical instrument with an articulable, interchangeable shaft in accordance with one or more aspects of the present disclosure. 
         FIG.  39    is a side view of the tip of the surgical instrument shown in  FIG.  38    in accordance with one or more aspects of the present disclosure. 
         FIG.  40    illustrates a cross-sectional view of an end effector of a surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  41    illustrates a logic diagram of a feedback system in accordance with one or more aspects of the present disclosure. 
         FIG.  42    illustrates a logic diagram of a feedback system in accordance with one or more aspects of the present disclosure. 
         FIG.  43    is a diagram of a smart sensor component in accordance with an aspect the present disclosure. 
         FIG.  44    illustrates one aspect of a circuit configured to convert signals from a first sensor and a plurality of secondary sensors into digital signals receivable by a processor in accordance with one or more aspects of the present disclosure. 
         FIG.  45    illustrates one aspect of an exploded view of a staple cartridge that comprises a flex cable connected to a magnetic field sensor and processor in accordance with one or more aspects of the present disclosure. 
         FIG.  46    illustrates the end effector shown in  FIG.  46    with a flex cable and without the shaft assembly in accordance with one or more aspects of the present disclosure. 
         FIGS.  47  and  48    illustrate an elongated channel portion of an end effector without the anvil or the staple cartridge, to illustrate how the flex cable shown in  FIG.  46    can be seated within the elongated channel in accordance with one or more aspects of the present disclosure. 
         FIG.  49    illustrates a flex cable, shown in  FIGS.  46 - 48   , alone in accordance with one or more aspects of the present disclosure. 
         FIG.  50    illustrates a close up view of the elongated channel shown in  FIGS.  114  and  115    with a staple cartridge coupled thereto in accordance with one or more aspects of the present disclosure. 
         FIGS.  51  and  52    illustrate one aspect of a distal sensor plug where  FIG.  51    illustrates a cutaway view of the distal sensor plug and  FIG.  52    further illustrates the magnetic field sensor and the processor operatively coupled to the flex board such that they are capable of communicating in accordance with one or more aspects of the present disclosure. 
         FIG.  53    illustrates an aspect of an end effector with a flex cable operable to provide power to sensors and electronics in the distal tip of the anvil portion in accordance with one or more aspects of the present disclosure. 
         FIG.  54    is a perspective view of an end effector of a surgical stapling instrument including a cartridge channel, a staple cartridge positioned in the cartridge channel, and an anvil in accordance with one or more aspects of the present disclosure. 
         FIG.  55    is a cross-sectional elevational view of the surgical stapling instrument of  FIG.  54    illustrating a sled and a firing member in an unfired position in accordance with one or more aspects of the present disclosure. 
         FIG.  56    is a detail view depicting the sled of  FIG.  55    in a partially advanced position and the firing member in its unfired position in accordance with one or more aspects of the present disclosure. 
         FIG.  57    illustrates one aspect of an end effector comprising a first sensor and a second sensor in accordance with one or more aspects of the present disclosure. 
         FIG.  58    is a logic diagram illustrating one aspect of a process for determining the thickness of a tissue section clamped between an anvil and a staple cartridge of an end effector in accordance with one or more aspects of the present disclosure. 
         FIG.  59    is a logic diagram illustrating one aspect of a process for determining the thickness of a tissue section clamped between the anvil and the staple cartridge of the end effector in accordance with one or more aspects of the present disclosure. 
         FIG.  60    illustrates one aspect of an end effector comprising a first sensor and a second sensor in accordance with one or more aspects of the present disclosure. 
         FIG.  61    illustrates one aspect of an end effector comprising a first sensor and a plurality of second sensors in accordance with one or more aspects of the present disclosure. 
         FIG.  62    illustrates one aspect of an end effector comprising a plurality of sensors in accordance with one or more aspects of the present disclosure. 
         FIG.  63    is a logic diagram illustrating one aspect of a process for determining one or more tissue properties based on a plurality of sensors in accordance with one or more aspects of the present disclosure. 
         FIG.  64    illustrates one aspect of an end effector comprising a plurality of sensors coupled to a jaw member in accordance with one or more aspects of the present disclosure. 
         FIG.  65    illustrates one aspect of a staple cartridge comprising a plurality of sensors formed integrally therein in accordance with one or more aspects of the present disclosure. 
         FIG.  66    is a logic diagram illustrating one aspect of a process for determining one or more parameters of a tissue section clamped within an end effector in accordance with one or more aspects of the present disclosure. 
         FIG.  67    illustrates one aspect of an end effector comprising a sensor comprising a specific sampling rate to limit or eliminate false signals in accordance with one or more aspects of the present disclosure. 
         FIG.  68    is a logic diagram illustrating one aspect of a process for generating a thickness measurement for a tissue section located between an anvil and a staple cartridge of an end effector in accordance with one or more aspects of the present disclosure. 
         FIGS.  69 A- 69 B  illustrate one aspect of an end effector comprising a pressure sensor in accordance with one or more aspects of the present disclosure. 
         FIG.  70    illustrates one aspect of an end effector comprising a second sensor located between a staple cartridge and a jaw member in accordance with one or more aspects of the present disclosure. 
         FIG.  71    is a logic diagram illustrating one aspect of a process for determining the thickness of a tissue section clamped in an end effector, according to  FIGS.  69 A- 69 B  or  FIG.  70    in accordance with one or more aspects of the present disclosure. 
         FIG.  72    illustrates one aspect of an end effector comprising a plurality of second sensors located between a staple cartridge and an elongated channel in accordance with one or more aspects of the present disclosure. 
         FIGS.  73 A and  73 B  further illustrate the effect of a full versus partial bite of tissue in accordance with one or more aspects of the present disclosure. 
         FIG.  74    illustrates an aspect of an end effector that is configured to determine the location of a cutting member or knife in accordance with one or more aspects of the present disclosure. 
         FIG.  75    illustrates an example of the code strip in operation with red LEDs and an infrared LED in accordance with one or more aspects of the present disclosure. 
         FIG.  76    illustrates a partial perspective view of an end effector of a surgical instrument comprising a staple cartridge in accordance with one or more aspects of the present disclosure. 
         FIG.  77    illustrates an elevational view of a portion of the end effector of  FIG.  76    in accordance with one or more aspects of the present disclosure. 
         FIG.  78    illustrates a logic diagram of a module of the surgical instrument of  FIG.  76    in accordance with one or more aspects of the present disclosure. 
         FIG.  79    illustrates a partial view of a cutting edge, an optical sensor, and a light source of the surgical instrument of  FIG.  76    in accordance with one or more aspects of the present disclosure. 
         FIG.  80    illustrates a partial view of a cutting edge, an optical sensor, and a light source of the surgical instrument of  FIG.  76    in accordance with one or more aspects of the present disclosure. 
         FIG.  81    illustrates a partial view of a cutting edge, an optical sensor, and a light source of the surgical instrument of  FIG.  76    in accordance with one or more aspects of the present disclosure. 
         FIG.  82    illustrates a partial view of a cutting edge, optical sensors, and light sources of the surgical instrument of  FIG.  76    in accordance with one or more aspects of the present disclosure. 
         FIG.  83    illustrates a partial view of a cutting edge, an optical sensor, and a light source of the surgical instrument of  FIG.  76    in accordance with one or more aspects of the present disclosure. 
         FIG.  84    illustrates a perspective view of a staple cartridge including a sharpness testing member in accordance with one or more aspects of the present disclosure. 
         FIG.  85    illustrates a logic diagram of a module of a surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  86    illustrates a logic diagram of a module of a surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  87    illustrates a logic diagram outlining a method for evaluating sharpness of a cutting edge of a surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  88    illustrates a flow chart outlining a method for determining whether a cutting edge of a surgical instrument is sufficiently sharp to transect tissue captured by the surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  89    illustrates a table showing predefined tissue thicknesses and corresponding predefined threshold forces in accordance with one or more aspects of the present disclosure. 
         FIG.  90    illustrates a logic diagram of a common controller for use with a plurality of motors of a surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  91    illustrates a partial elevational view of the handle of the surgical instrument with a removed outer casing in accordance with one or more aspects of the present disclosure. 
         FIG.  92    illustrates a partial elevational view of the surgical instrument with a removed outer casing in accordance with one or more aspects of the present disclosure. 
         FIG.  93 A  illustrates a side angle view of an end effector with the anvil in a closed position, illustrating one located on either side of the cartridge deck in accordance with one or more aspects of the present disclosure. 
         FIG.  93 B  illustrates a three-quarter angle view of the end effector with the anvil in an open position, and one LED located on either side of the cartridge deck in accordance with one or more aspects of the present disclosure. 
         FIG.  94 A  illustrates a side angle view of an end effector with the anvil in a closed position and a plurality of LEDs located on either side of the cartridge deck in accordance with one or more aspects of the present disclosure. 
         FIG.  94 B  illustrates a three-quarter angle view of the end effector with the anvil in an open position, and a plurality of LEDs located on either side of the cartridge deck in accordance with one or more aspects of the present disclosure. 
         FIG.  95 A  illustrates a side angle view of an end effector with the anvil in a closed position, and a plurality of LEDs from the proximal to the distal end of the staple cartridge, on either side of the cartridge deck in accordance with one or more aspects of the present disclosure. 
         FIG.  95 B  illustrates a three-quarter angle view of the end effector with the anvil in an open position, illustrating a plurality of LEDs from the proximal to the distal end of the staple cartridge, and on either side of the cartridge deck in accordance with one or more aspects of the present disclosure. 
         FIG.  96    is a circuit diagram of an example power assembly of a surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  97    is a circuit diagram of an example power assembly of a surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  98    is a schematic block diagram of a control system of a surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  99    is a schematic block diagram of a control system of a surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  100    is a schematic diagram of an absolute positioning system comprising a controlled motor drive circuit arrangement comprising a sensor arrangement in accordance with one or more aspects of the present disclosure. 
         FIG.  101    is a detail perspective view of a sensor arrangement for an absolute positioning system in accordance with one or more aspects of the present disclosure. 
         FIG.  102    is an exploded perspective view of the sensor arrangement for an absolute positioning system showing a control circuit board assembly and the relative alignment of the elements of the sensor arrangement in accordance with one or more aspects of the present disclosure. 
         FIG.  103    is a schematic diagram of one aspect of a position sensor for an absolute positioning system comprising a magnetic rotary absolute positioning system in accordance with one or more aspects of the present disclosure. 
         FIG.  104    is a schematic illustrating a system for controlling the speed of a motor and/or the speed of a drivable member of a surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  105    is a schematic illustrating another system for controlling the speed of a motor and/or the speed of a drivable member of a surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  106    illustrates a perspective view of a surgical instrument according to various aspects in accordance with one or more aspects of the present disclosure. 
         FIG.  107    illustrates a method of controlling a closing motion of the surgical instrument of  FIG.  106    according to various aspects in accordance with one or more aspects of the present disclosure. 
         FIG.  108    illustrates an example graph showing a curve representative of a closing force signal over time for various aspects of the surgical instrument of  FIG.  106    in accordance with one or more aspects of the present disclosure. 
         FIG.  109    illustrates an example graph showing a curve representative of a firing force signal over time and a curve representative of a knife velocity over time for various aspects of the surgical instrument of  FIG.  106    in accordance with one or more aspects of the present disclosure. 
         FIG.  110    illustrates an example graph showing a curve representative of a firing force signal and a knife position over time for various aspects of the surgical instrument of  FIG.  106    in accordance with one or more aspects of the present disclosure. 
         FIG.  111    illustrates an example graph showing a curve representative of a firing force signal and a curve representative of a knife velocity over time for various aspects of the surgical instrument of  FIG.  106    in accordance with one or more aspects of the present disclosure. 
         FIG.  112    illustrates an example graph showing a curve representative of a closing force FC over time t for various aspects of the surgical instrument of  FIG.  106    and a curve representative of a firing force FF over time t of the surgical instrument of  FIG.  106    in accordance with one or more aspects of the present disclosure. 
         FIG.  113    illustrates various aspects of a direction sensor of the surgical instrument of  FIG.  106    in accordance with one or more aspects of the present disclosure. 
         FIG.  114    illustrates various aspects of a direction sensor of the surgical instrument of  FIG.  106    in accordance with one or more aspects of the present disclosure. 
         FIG.  115    illustrates a perspective view of another surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  116    illustrates a method of controlling a firing motion of the surgical instrument of  FIG.  115    in accordance with one or more aspects of the present disclosure. 
         FIG.  117    illustrates an example graph showing a curve representative of a firing force signal over time for the surgical instrument of  FIG.  115    in accordance with one or more aspects of the present disclosure. 
         FIG.  118    illustrates another example graph showing a curve representative of a firing force signal over time for the surgical instrument of  FIG.  115    in accordance with one or more aspects of the present disclosure. 
         FIG.  119    illustrates an example graph showing a curve representative of a closing force FC over time t for various aspects of the surgical instrument and a curve representative of a firing force FF over time t for the surgical instrument of  FIG.  115    in accordance with one or more aspects of the present disclosure. 
         FIG.  120    illustrates an example graph showing a curve representative of a firing force signal and a knife position over time and a curve representative of a knife velocity over time for the surgical instrument of  FIG.  115    in accordance with one or more aspects of the present disclosure. 
         FIG.  121    illustrates a perspective view of another surgical instrument in accordance with one or more aspects of the present disclosure. 
         FIG.  122    illustrates a method of controlling a firing motion of the surgical instrument of  FIG.  121    in accordance with one or more aspects of the present disclosure. 
         FIG.  123    illustrates an example graph showing a curve representative of a firing force signal over time and a knife position over time and a curve representative of a knife velocity over time for the surgical instrument of  FIG.  121    in accordance with one or more aspects of the present disclosure. 
         FIG.  124    illustrates an example graph showing the rate of closure of the jaws for the surgical instrument of  FIG.  121    in accordance with one or more aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Applicant of the present application owns the following patent applications that were filed on Apr. 15, 2016 and which are each herein incorporated by reference in their respective entireties:
     U.S. patent application Ser. No. 15/130,575, entitled STAPLE FORMATION DEFECTION MECHANISMS, now U.S. Pat. No. 10,456,137;   U.S. patent application Ser. No. 15/130,582, entitled SURGICAL INSTRUMENT WITH DETECTION SENSORS, now U.S. Pat. No. 10,426,467;   U.S. patent application Ser. No. 15/130,588, entitled SURGICAL INSTRUMENT WITH IMPROVED STOP/START CONTROL DURING A FIRING MOTION, now U.S. Pat. No. 10,492,783;   U.S. patent application Ser. No. 15/130,595, entitled SURGICAL INSTRUMENT WITH ADJUSTABLE STOP/START CONTROL DURING A FIRING MOTION, now U.S. Pat. No. 10,405,859;   U.S. patent application Ser. No. 15/130,571, entitled SURGICAL INSTRUMENT WITH MULTIPLE PROGRAM RESPONSES DURING A FIRING MOTION, now U.S. Pat. No. 10,357,247;   U.S. patent application Ser. No. 15/130,581, entitled MODULAR SURGICAL INSTRUMENT WITH CONFIGURABLE OPERATING MODE, now U.S. Pat. No. 10,335,145;   U.S. patent application Ser. No. 15/130,590, entitled SYSTEMS AND METHODS FOR CONTROLLING A SURGICAL STAPLING AND CUTTING INSTRUMENT, now U.S. Patent Application Publication No. 2017/0292613; and   U.S. patent application Ser. No. 15/130,596, entitled SYSTEMS AND METHODS FOR CONTROLLING A SURGICAL STAPLING AND CUTTING INSTRUMENT, now U.S. Patent Application Publication No. 2017/0296169.   

     The present disclosure provides an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these aspects are illustrated in the accompanying drawings. Those of ordinary skill in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting examples. The features illustrated or described in connection with one example may be combined with the features of other examples. Such modifications and variations are intended to be included within the scope of the present disclosure. 
     Various example devices and methods are provided for performing laparoscopic and minimally invasive surgical procedures. However, the person of ordinary skill in the art will readily appreciate that the various methods and devices disclosed herein can be used in numerous surgical procedures and applications including, for example, in connection with open surgical procedures. As the present Detailed Description proceeds, those of ordinary skill in the art will further appreciate that the various instruments disclosed herein can be inserted into a body in any way, such as through a natural orifice, through an incision or puncture hole formed in tissue, etc. The working portions or end effector portions of the instruments can be inserted directly into a patient&#39;s body or can be inserted through an access device that has a working channel through which the end effector and elongated shaft of a surgical instrument can be advanced. 
     In one aspect, the present disclosure provides a motorized surgical stapling and cutting instrument configured to provide different program responses/modifications based on rate of change while approaching a threshold. In one aspect, the present disclosure provides a motorized surgical stapling and cutting instrument configure to provide variable control program responses (pause, slow down, speed up, backup and re-advance, and stop) depending on how fast the load is increasing or decreasing (slope) as it approaches predefined staged thresholds (load, current, pressure, velocity). In one aspect, the motorized surgical instrument comprises a controller that provides variable functional response based on rate of change of load while approaching a predefined threshold. A rapid slope ramp causes the control program to stop advancing the cutting member and create an oscillating motion to move through obstruction. The control program vibrates the anvil to clamp and stabilize the tissue. The control program causes repetitive or oscillating advancement to improve compression on the tissue. The rate of slope change of load can be employed by the control program to determine the rate that the cutting member can to advance after the forced pause (tissue creep). 
     Before describing various aspects of a motorized stapling and cutting instrument (surgical instrument) as described in connection with  FIGS.  106 - 124   , the present disclosure first turns to  FIGS.  1 - 105    for a general description of the mechanical and electrical platform upon which the present motorized surgical instrument may be implemented and provides the background necessary to appreciate the underlying operation and functionality of the motorized surgical instrument. Accordingly,  FIGS.  1 - 14    provide an example of a general description of the underlying mechanical platform upon which the present motorized stapling and cutting instrument may be implemented.  FIGS.  15 - 21    describe examples of the general underlying microcontroller, motor drive, and electrical interconnection platform upon which the present motorized surgical instrument may be implemented.  FIGS.  22 - 34    describe example end effector channel frames and measuring forces applied to tissue located between the anvil and the staple cartridge of the end effector.  FIGS.  35 - 37    described example circuits for controlling the functionality of the present motorized surgical instrument.  FIGS.  38 - 95    describe example sensors and feedback systems to utilize the sensors outputs to implement the present motorized surgical instrument.  FIGS.  97 - 97    describe example power assemblies for powering the present motorized surgical instrument.  FIGS.  98 - 105    describe example control systems for controlling motor speed and drivable members of the present surgical instrument includes sensors and feedback elements therefor. Upon familiarization with the underlying mechanical and electrical platform upon which the present motorized surgical instrument may be implemented, the reader is directed to the description in connection with  FIGS.  106 - 124    for a description of a motorized surgical stapling and cutting instrument configured to provide different program responses/modifications based on rate of change while approaching a threshold. 
     Accordingly, turning now to the figures,  FIGS.  1 - 6    depict a motor-driven surgical instrument  10  for cutting and fastening that may or may not be reused. In the illustrated examples, the surgical instrument  10  includes a housing  12  that comprises a handle assembly  14  that is configured to be grasped, manipulated and actuated by the clinician. The housing  12  is configured for operable attachment to an interchangeable shaft assembly  200  that has an end effector  300  operably coupled thereto that is configured to perform one or more surgical tasks or procedures. As the present Detailed Description proceeds, it will be understood that the various unique and novel arrangements of the various forms of interchangeable shaft assemblies disclosed herein also may be effectively employed in connection with robotically-controlled surgical systems. Thus, the term “housing” also may encompass a housing or similar portion of a robotic system that houses or otherwise operably supports at least one drive system that is configured to generate and apply at least one control motion which could be used to actuate the interchangeable shaft assemblies disclosed herein and their respective equivalents. The term “frame” may refer to a portion of a handheld surgical instrument. The term “frame” also may represent a portion of a robotically controlled surgical instrument and/or a portion of the robotic system that may be used to operably control a surgical instrument. For example, the interchangeable shaft assemblies disclosed herein may be employed with various robotic systems, instruments, components and methods disclosed in U.S. Pat. No. 9,072,535, entitled SURGICAL STAPLING INSTRUMENTS WITH ROTATABLE STAPLE DEPLOYMENT ARRANGEMENTS, which is incorporated by reference herein in its entirety. 
     The housing  12  depicted in  FIGS.  1 - 2    is shown in connection with an interchangeable shaft assembly  200  that includes an end effector  300  that comprises a surgical cutting and fastening device that is configured to operably support a surgical staple cartridge  304  therein. The housing  12  may be configured for use in connection with interchangeable shaft assemblies that include end effectors that are adapted to support different sizes and types of staple cartridges, have different shaft lengths, sizes, and types, etc. In addition, the housing  12  also may be effectively employed with a variety of other interchangeable shaft assemblies including those assemblies that are configured to apply other motions and forms of energy such as, for example, radio frequency (RF) energy, ultrasonic energy and/or motion to end effector arrangements adapted for use in connection with various surgical applications and procedures. Furthermore, the end effectors, shaft assemblies, handles, surgical instruments, and/or surgical instrument systems can utilize any suitable fastener, or fasteners, to fasten tissue. For instance, a fastener cartridge comprising a plurality of fasteners removably stored therein can be removably inserted into and/or attached to the end effector of a shaft assembly. 
       FIG.  1    illustrates the surgical instrument  10  with an interchangeable shaft assembly  200  operably coupled thereto.  FIG.  2    illustrates attachment of the interchangeable shaft assembly  200  to the housing  12  or handle assembly  14 . As shown in  FIG.  4   , the handle assembly  14  may comprise a pair of interconnectable handle housing segments  16  and  18  that may be interconnected by screws, snap features, adhesive, etc. In the illustrated arrangement, the handle housing segments  16 ,  18  cooperate to form a pistol grip portion  19  that can be gripped and manipulated by the clinician. As will be discussed in further detail below, the handle assembly  14  operably supports a plurality of drive systems therein that are configured to generate and apply various control motions to corresponding portions of the interchangeable shaft assembly that is operably attached thereto. 
     Referring now to  FIG.  4   , the handle assembly  14  may further include a frame  20  that operably supports a plurality of drive systems. For example, the frame  20  can operably support a “first” or closure drive system, generally designated as  30 , which may be employed to apply closing and opening motions to the interchangeable shaft assembly  200  that is operably attached or coupled thereto. In at least one form, the closure drive system  30  may include an actuator in the form of a closure trigger  32  that is pivotally supported by the frame  20 . More specifically, as illustrated in  FIG.  4   , the closure trigger  32  is pivotally coupled to the handle assembly  14  by a pivot pin  33 . Such arrangement enables the closure trigger  32  to be manipulated by a clinician such that when the clinician grips the pistol grip portion  19  of the handle assembly  14 , the closure trigger  32  may be easily pivoted from a starting or “unactuated” position to an “actuated” position and more particularly to a fully compressed or fully actuated position. The closure trigger  32  may be biased into the unactuated position by spring or other biasing arrangement (not shown). In various forms, the closure drive system  30  further includes a closure linkage assembly  34  that is pivotally coupled to the closure trigger  32 . As shown in  FIG.  4   , the closure linkage assembly  34  may include a first closure link  36  and a second closure link  38  that are pivotally coupled to the closure trigger  32  by a pin  35 . The second closure link  38  also may be referred to herein as an “attachment member” and include a transverse attachment pin  37 . 
     Still referring to  FIG.  4   , it can be observed that the first closure link  36  may have a an end or locking wall  39  thereon that is configured to cooperate with a closure release assembly  60  that is pivotally coupled to the frame  20 . In at least one form, the closure release assembly  60  may comprise a closure release button assembly  62  that has a distally protruding locking pawl  64  formed thereon. The closure release button assembly  62  may be pivoted in a counterclockwise direction by a release spring (not shown). As the clinician depresses the closure trigger  32  from its unactuated position towards the pistol grip portion  19  of the handle assembly  14 , the first closure link  36  pivots upward to a point wherein the locking pawl  64  drops into retaining engagement with the locking wall  39  on the first closure link  36  thereby preventing the closure trigger  32  from returning to the unactuated position. Thus, the closure release assembly  60  serves to lock the closure trigger  32  in the fully actuated position. When the clinician desires to unlock the closure trigger  32  to permit it to be biased to the unactuated position, the clinician simply pivots the closure release button assembly  62  such that the locking pawl  64  is moved out of engagement with the locking wall  39  on the first closure link  36 . When the locking pawl  64  has been moved out of engagement with the first closure link  36 , the closure trigger  32  may pivot back to the unactuated position. Other closure trigger locking and release arrangements also may be employed. 
     Further to the above,  FIGS.  10 - 11    illustrate the closure trigger  32  in its unactuated position which is associated with an open, or unclamped, configuration of the interchangeable shaft assembly  200  in which tissue can be positioned between the jaws of the interchangeable shaft assembly  200 .  FIG.  12    illustrates the closure trigger  32  in its actuated position which is associated with a closed, or clamped, configuration of the interchangeable shaft assembly  200  in which tissue is clamped between the jaws of the interchangeable shaft assembly  200 . Upon comparing  FIGS.  11  and  13   , the reader will appreciate that, when the closure trigger  32  is moved from its unactuated position ( FIG.  11   ) to its actuated position ( FIG.  13   ), the closure release button assembly  62  is pivoted between a first position ( FIG.  11   ) and a second position ( FIG.  13   ). The rotation of the closure release button assembly  62  can be referred to as being an upward rotation; however, at least a portion of the closure release button assembly  62  is being rotated toward the circuit board  100 . Referring to  FIG.  4   , the closure release button assembly  62  can include an arm  61  extending therefrom and a magnetic element  63 , such as a permanent magnet, for example, mounted to the arm  61 . When the closure release button assembly  62  is rotated from its first position to its second position, the magnetic element  63  can move toward the circuit board  100 . The circuit board  100  can include at least one sensor configured to detect the movement of the magnetic element  63 . In at least one aspect, a magnetic field sensor  65 , for example, can be mounted to the bottom surface of the circuit board  100 . The magnetic field sensor  65  can be configured to detect changes in a magnetic field surrounding the magnetic field sensor  65  caused by the movement of the magnetic element  63 . The magnetic field sensor  65  can be in signal communication with a controller  1500 , for example, which can determine whether the closure release button assembly  62  is in its first position, which is associated with the unactuated position of the closure trigger  32  and the open configuration of the end effector, its second position, which is associated with the actuated position of the closure trigger  32  and the closed configuration of the end effector, and/or any position between the first position and the second position. 
     As used throughout the present disclosure, a magnetic field sensor may be a Hall effect sensor, search coil, fluxgate, optically pumped, nuclear precession, SQUID, Hall-effect, anisotropic magnetoresistance, giant magnetoresistance, magnetic tunnel junctions, giant magnetoimpedance, magnetostrictive/piezoelectric composites, magnetodiode, magnetotransistor, fiber optic, magnetooptic, and microelectromechanical systems-based magnetic sensors, among others. 
     In at least one form, the handle assembly  14  and the frame  20  may operably support another drive system referred to herein as a firing drive system  80  that is configured to apply firing motions to corresponding portions of the interchangeable shaft assembly attached thereto. The firing drive system may  80  also be referred to herein as a “second drive system”. The firing drive system  80  may employ an electric motor  82 , located in the pistol grip portion  19  of the handle assembly  14 . In various forms, the electric motor  82  may be a DC brushed driving motor having a maximum rotation of, approximately, 25,000 RPM, for example. In other arrangements, the motor may include a brushless motor, a cordless motor, a synchronous motor, a stepper motor, or any other suitable electric motor. The electric motor  82  may be powered by a power source  90  that in one form may comprise a removable power pack  92 . As shown in  FIG.  4   , for example, the removable power pack  92  may comprise a proximal housing portion  94  that is configured for attachment to a distal housing portion  96 . The proximal housing portion  94  and the distal housing portion  96  are configured to operably support a plurality of batteries  98  therein. Batteries  98  may each comprise, for example, a Lithium Ion (“LI”) or other suitable battery. The distal housing portion  96  is configured for removable operable attachment to a control circuit board  100  which is also operably coupled to the electric motor  82 . A number of batteries  98  may be connected in series may be used as the power source for the surgical instrument  10 . In addition, the power source  90  may be replaceable and/or rechargeable. 
     As outlined above with respect to other various forms, the electric motor  82  can include a rotatable shaft (not shown) that operably interfaces with a gear reducer assembly  84  that is mounted in meshing engagement with a with a set, or rack, of drive teeth  122  on a longitudinally movable drive member  120 . In use, a voltage polarity provided by the power source  90  can operate the electric motor  82  in a clockwise direction wherein the voltage polarity applied to the electric motor by the battery can be reversed in order to operate the electric motor  82  in a counter-clockwise direction. When the electric motor  82  is rotated in one direction, the longitudinally movable drive member  120  will be axially driven in the distal direction “DD”. When the electric motor  82  is driven in the opposite rotary direction, the longitudinally movable drive member  120  will be axially driven in a proximal direction “PD”. The handle assembly  14  can include a switch which can be configured to reverse the polarity applied to the electric motor  82  by the power source  90 . As with the other forms described herein, the handle assembly  14  can also include a sensor that is configured to detect the position of the longitudinally movable drive member  120  and/or the direction in which the longitudinally movable drive member  120  is being moved. 
     Actuation of the electric motor  82  can be controlled by a firing trigger  130  that is pivotally supported on the handle assembly  14 . The firing trigger  130  may be pivoted between an unactuated position and an actuated position. The firing trigger  130  may be biased into the unactuated position by a spring  132  or other biasing arrangement such that when the clinician releases the firing trigger  130 , it may be pivoted or otherwise returned to the unactuated position by the spring  132  or biasing arrangement. In at least one form, the firing trigger  130  can be positioned “outboard” of the closure trigger  32  as was discussed above. In at least one form, a firing trigger safety button  134  may be pivotally mounted to the closure trigger  32  by pin  35 . The firing trigger safety button  134  may be positioned between the firing trigger  130  and the closure trigger  32  and have a pivot arm  136  protruding therefrom. See  FIG.  4   . When the closure trigger  32  is in the unactuated position, the firing trigger safety button  134  is contained in the handle assembly  14  where the clinician cannot readily access it and move it between a safety position preventing actuation of the firing trigger  130  and a firing position wherein the firing trigger  130  may be fired. As the clinician depresses the closure trigger  32 , the firing trigger safety button  134  and the firing trigger  130  pivot down wherein they can then be manipulated by the clinician. 
     As discussed above, the handle assembly  14  can include a closure trigger  32  and a firing trigger  130 . Referring to  FIGS.  11 - 13   , the firing trigger  130  can be pivotably mounted to the closure trigger  32 . The closure trigger  32  can include an arm  31  extending therefrom and the firing trigger  130  can be pivotably mounted to the arm  31  about a pivot pin  33 . When the closure trigger  32  is moved from its unactuated position ( FIG.  11   ) to its actuated position ( FIG.  13   ), the firing trigger  130  can descend downwardly, as outlined above. After the firing trigger safety button  134  has been moved to its firing position, referring primarily to  FIG.  18 A , the firing trigger  130  can be depressed to operate the motor of the surgical instrument firing system. In various instances, the handle assembly  14  can include a tracking system, such as system  800 , for example, configured to determine the position of the closure trigger  32  and/or the position of the firing trigger  130 . With primary reference to  FIGS.  11  and  13   , the tracking system  800  can include a magnetic element, such as magnet  802 , for example, which is mounted to an arm  801  extending from the firing trigger  130 . The tracking system  800  can comprise one or more sensors, such as a first magnetic field sensor  803  and a second magnetic field sensor  804 , for example, which can be configured to track the position of the magnet  802 . 
     Upon comparing  FIGS.  11  and  13   , the reader will appreciate that, when the closure trigger  32  is moved from its unactuated position to its actuated position, the magnet  802  can move between a first position adjacent the first magnetic field sensor  803  and a second position adjacent the second magnetic field sensor  804 . 
     Upon comparing  FIGS.  11  and  13   , the reader will further appreciate that, when the firing trigger  130  is moved from an unfired position ( FIG.  11   ) to a fired position ( FIG.  13   ), the magnet  802  can move relative to the second magnetic field sensor  804 . The first and second magnetic field sensors  803 ,  804  can track the movement of the magnet  802  and can be in signal communication with a controller on the circuit board  100 . With data from the first magnetic field sensor  803  and/or the second magnetic field sensor  804 , the controller can determine the position of the magnet  802  along a predefined path and, based on that position, the controller can determine whether the closure trigger  32  is in its unactuated position, its actuated position, or a position therebetween. Similarly, with data from the first magnetic field sensor  803  and/or the second magnetic field sensor  804 , the controller can determine the position of the magnet  802  along a predefined path and, based on that position, the controller can determine whether the firing trigger  130  is in its unfired position, its fully fired position, or a position therebetween. 
     As indicated above, in at least one form, the longitudinally movable drive member  120  has a rack of drive teeth  122  formed thereon for meshing engagement with a corresponding drive gear  86  of the gear reducer assembly  84 . At least one form also includes a manually-actuatable bailout assembly  140  that is configured to enable the clinician to manually retract the longitudinally movable drive member  120  should the electric motor  82  become disabled. The bailout assembly  140  may include a lever or handle assembly  14  that is configured to be manually pivoted into ratcheting engagement with teeth  124  also provided in the longitudinally movable drive member  120 . Thus, the clinician can manually retract the longitudinally movable drive member  120  by using the handle assembly  14  to ratchet the longitudinally movable drive member  120  in the proximal direction “PD”. U.S. Pat. No. 8,608,045, entitled POWERED SURGICAL CUTTING AND STAPLING APPARATUS WITH MANUALLY RETRACTABLE FIRING SYSTEM discloses bailout arrangements and other components, arrangements and systems that also may be employed with the various instruments disclosed herein. U.S. Pat. No. 8,608,045, is herein incorporated by reference in its entirety. 
     Turning now to  FIG.  1   , the interchangeable shaft assembly  200  includes an end effector  300  that comprises an elongated channel  302  that is configured to operably support a surgical staple cartridge  304  therein. The end effector  300  may further include an anvil  306  that is pivotally supported relative to the elongated channel  302 . The interchangeable shaft assembly  200  may further include an articulation joint  270  and an articulation lock  350  ( FIG.  7   ) which can be configured to releasably hold the end effector  300  in a desired position relative to a shaft axis SA-SA. Details regarding the construction and operation of the end effector  300 , the articulation joint  270  and the articulation lock  350  are set forth in U.S. Patent Application Publication No. 2014/0263541, entitled ARTICULATABLE SURGICAL INSTRUMENT COMPRISING AN ARTICULATION LOCK, which is herein incorporated by reference in its entirety. As shown in  FIG.  7   , the interchangeable shaft assembly  200  can further include a proximal housing or nozzle  201  comprised of nozzle portions  202 ,  203 . The interchangeable shaft assembly  200  can further include a closure tube  260  which can be utilized to close and/or open the anvil  306  of the end effector  300 . Primarily referring now to  FIG.  7   , the interchangeable shaft assembly  200  can include a spine  210  which can be configured to fixably support a shaft frame  212  of the articulation lock  350 . See  FIG.  7   . The spine  210  can be configured to, one, slidably support a firing member  220  therein and, two, slidably support the closure tube  260  which extends around the spine  210 . The spine  210  can also be configured to slidably support an articulation driver  230 . The articulation driver  230  has a distal end  231  that is configured to operably engage the articulation lock  350 . The articulation lock  350  interfaces with an articulation frame  352  that is adapted to operably engage a drive pin (not shown) on the end effector frame (not shown). As indicated above, further details regarding the operation of the articulation lock  350  and the articulation frame may be found in U.S. Patent Application Publication No. 2014/0263541. In various circumstances, the spine  210  can comprise a proximal end  211  which is rotatably supported in a chassis  240 . In one arrangement, for example, the proximal end  211  of the spine  210  has a thread  214  formed thereon for threaded attachment to a spine bearing  216  configured to be supported within the chassis  240 . Such an arrangement facilitates rotatable attachment of the spine  210  to the chassis  240  such that the spine  210  may be selectively rotated about a shaft axis SA-SA relative to the chassis  240 . 
     The interchangeable shaft assembly  200  includes a closure shuttle  250  that is slidably supported within the chassis  240  such that it may be axially moved relative thereto. As shown in  FIG.  3   , the closure shuttle  250  includes a pair of proximally-protruding hooks  252  that are configured for attachment to the transverse attachment pin  37  that is attached to the second closure link  38  as will be discussed in further detail below. A proximal end  261  of the closure tube  260  is coupled to the closure shuttle  250  for relative rotation thereto. For example, a U shaped connector  263  is inserted into an annular slot  262  in the proximal end  261  of the closure tube  260  and is retained within vertical slots  253  in the closure shuttle  250 . Such an arrangement serves to attach the closure tube  260  to the closure shuttle  250  for axial travel therewith while enabling the closure tube  260  to rotate relative to the closure shuttle  250  about the shaft axis SA-SA. A closure spring  268  is journaled on the closure tube  260  and serves to bias the closure tube  260  in the proximal direction “PD” which can serve to pivot the closure trigger into the unactuated position when the shaft assembly is operably coupled to the handle assembly  14 . 
     In at least one form, the interchangeable shaft assembly  200  may further include an articulation joint  270 . Other interchangeable shaft assemblies, however, may not be capable of articulation. According to various forms, the double pivot closure sleeve assembly  271  includes an end effector closure sleeve assembly  272  having upper and lower distally projecting tangs  273 ,  274 . An end effector closure sleeve assembly  272  includes a horseshoe aperture  275  and a tab  276  for engaging an opening tab on the anvil  306  in the various manners described in U.S. Patent Application Publication No. 2014/0263541. As described in further detail therein, the horseshoe aperture  275  and tab  276  engage a tab on the anvil when the anvil  306  is opened. An upper double pivot link  277  includes upwardly projecting distal and proximal pivot pins that engage respectively an upper distal pin hole in the upper proximally projecting tang  273  and an upper proximal pin hole in an upper distally projecting tang  264  on the closure tube  260 . A lower double pivot link  278  includes upwardly projecting distal and proximal pivot pins that engage respectively a lower distal pin hole in the lower proximally projecting tang  274  and a lower proximal pin hole in the lower distally projecting tang  265 . See also  FIG.  7   . 
     In use, the closure tube  260  is translated distally (direction “DD”) to close the anvil  306 , for example, in response to the actuation of the closure trigger  32 . The anvil  306  is closed by distally translating the closure tube  260  and thus the end effector closure sleeve assembly  272 , causing it to strike a proximal surface on the anvil  306  in the manner described in the aforementioned reference U.S. Patent Application Publication No. 2014/0263541. As was also described in detail in that reference, the anvil  306  is opened by proximally translating the closure tube  260  and the end effector closure sleeve assembly  272 , causing tab  276  and the horseshoe aperture  275  to contact and push against the anvil tab to lift the anvil  306 . In the anvil-open position, the closure tube  260  is moved to its proximal position. 
     As indicated above, the surgical instrument  10  may further include an articulation lock  350  of the types and construction described in further detail in U.S. Patent Application Publication No. 2014/0263541, which can be configured and operated to selectively lock the end effector  300  in position. Such arrangement enables the end effector  300  to be rotated, or articulated, relative to the closure tube  260  when the articulation lock  350  is in its unlocked state. In such an unlocked state, the end effector  300  can be positioned and pushed against soft tissue and/or bone, for example, surrounding the surgical site within the patient in order to cause the end effector  300  to articulate relative to the closure tube  260 . The end effector  300  also may be articulated relative to the closure tube  260  by an articulation driver  230 . 
     As was also indicated above, the interchangeable shaft assembly  200  further includes a firing member  220  that is supported for axial travel within the spine  210 . The firing member  220  includes an intermediate firing shaft  222  that is configured for attachment to a distal cutting portion or knife bar  280 . The firing member  220  also may be referred to herein as a “second shaft” and/or a “second shaft assembly”. As shown in  FIG.  7   , the intermediate firing shaft  222  may include a longitudinal slot  223  in the distal end thereof which can be configured to receive a tab  284  on the proximal end  282  of the knife bar  280 . The longitudinal slot  223  and the proximal end  282  can be sized and configured to permit relative movement therebetween and can comprise a slip joint  286 . The slip joint  286  can permit the intermediate firing shaft  222  of the firing member  220  to be moved to articulate the end effector  300  without moving, or at least substantially moving, the knife bar  280 . Once the end effector  300  has been suitably oriented, the intermediate firing shaft  222  can be advanced distally until a proximal sidewall of the longitudinal slot  223  comes into contact with the tab  284  in order to advance the knife bar  280  and fire the staple cartridge positioned within the channel  302 . As can be further seen in  FIG.  7   , the spine  210  has an elongated opening or window  213  therein to facilitate assembly and insertion of the intermediate firing shaft  222  into the spine  210 . Once the intermediate firing shaft  222  has been inserted therein, a top frame segment  215  may be engaged with the shaft frame  212  to enclose the intermediate firing shaft  222  and knife bar  280  therein. Further description of the operation of the firing member  220  may be found in U.S. Patent Application Publication No. 2014/0263541. 
     Further to the above, the interchangeable shaft assembly  200  can include a clutch assembly  400  which can be configured to selectively and releasably couple the articulation driver  230  to the firing member  220 . In one form, the clutch assembly  400  includes a lock collar, or lock sleeve  402 , positioned around the firing member  220  wherein the lock sleeve  402  can be rotated between an engaged position in which the lock sleeve  402  couples the articulation driver  360  to the firing member  220  and a disengaged position in which the articulation driver  360  is not operably coupled to the firing member  220 . When lock sleeve  402  is in its engaged position, distal movement of the firing member  220  can move the articulation driver  360  distally and, correspondingly, proximal movement of the firing member  220  can move the articulation driver  230  proximally. When lock sleeve  402  is in its disengaged position, movement of the firing member  220  is not transmitted to the articulation driver  230  and, as a result, the firing member  220  can move independently of the articulation driver  230 . In various circumstances, the articulation driver  230  can be held in position by the articulation lock  350  when the articulation driver  230  is not being moved in the proximal or distal directions by the firing member  220 . 
     As shown in  FIGS.  7 - 9   , the interchangeable shaft assembly  200  further includes a switch drum  500  that is rotatably received on the closure tube  260 . The switch drum  500  comprises a hollow shaft segment  502  that has a shaft boss  504  formed thereon for receive an outwardly protruding actuation pin  410  therein. In various circumstances, the actuation pin  410  extends through a slot  267  into a longitudinal slot  408  provided in the lock sleeve  402  to facilitate axial movement of the lock sleeve  402  when it is engaged with the articulation driver  230 . A rotary torsion spring  420  is configured to engage the shaft boss  504  on the switch drum  500  and a portion of the nozzle portion  203  as shown in  FIG.  8    to apply a biasing force to the switch drum  500 . The switch drum  500  can further comprise at least partially circumferential openings  506  defined therein which, referring to  FIGS.  5  and  6   , can be configured to receive circumferential mounts  204 ,  205  extending from the nozzle portions  202 ,  203  and permit relative rotation, but not translation, between the switch drum  500  and the nozzle  201 . As shown in those Figures, the circumferential mounts  204 ,  205  also extend through openings  266  in the closure tube  260  to be seated in recesses located in the spine  210 . However, rotation of the nozzle  201  to a point where the circumferential mounts  204 ,  205  reach the end of their respective partially circumferential openings  506  in the switch drum  500  will result in rotation of the switch drum  500  about the shaft axis SA-SA. Rotation of the switch drum  500  will ultimately result in the rotation of the actuation pin  410  and the lock sleeve  402  between its engaged and disengaged positions. Thus, in essence, the nozzle  201  may be employed to operably engage and disengage the articulation drive system with the firing drive system in the various manners described in further detail in U.S. Patent Application Publication No. 2014/0263541. 
     As also illustrated in  FIGS.  7 - 9   , the interchangeable shaft assembly  200  can comprise a slip ring assembly  600  which can be configured to conduct electrical power to and/or from the end effector  300  and/or communicate signals to and/or from the end effector  300 , for example. The slip ring assembly  600  can comprise a proximal connector flange  604  mounted to a chassis mounting flange  242  extending from the chassis  240  and a distal connector flange  601  positioned within a slot defined in the nozzle portions  202 ,  203 . The proximal connector flange  604  can comprise a first face and the distal connector flange  601  can comprise a second face which is positioned adjacent to and movable relative to the first face. The distal connector flange  601  can rotate relative to the proximal connector flange  604  about the shaft axis SA-SA. The proximal connector flange  604  can comprise a plurality of concentric, or at least substantially concentric, conductors  602  defined in the first face thereof. A connector  607  can be mounted on the proximal side of the distal connector flange  601  and may have a plurality of contacts (not shown) wherein each contact corresponds to and is in electrical contact with one of the conductors  602 . Such an arrangement permits relative rotation between the proximal connector flange  604  and the distal connector flange  601  while maintaining electrical contact therebetween. The proximal connector flange  604  can include an electrical connector  606  which can place the conductors  602  in signal communication with a shaft circuit board  610  mounted to the chassis  240 , for example. In at least one instance, a wiring harness comprising a plurality of conductors can extend between the electrical connector  606  and the shaft circuit board  610 . The electrical connector  606  may extend proximally through a connector opening  243  defined in the chassis mounting flange  242 . U.S. Patent Application Publication No. 2014/0263551, entitled STAPLE CARTRIDGE TISSUE THICKNESS SENSOR SYSTEM, is incorporated herein by reference in its entirety. U.S. Patent Application Publication No. 2014/0263552, entitled STAPLE CARTRIDGE TISSUE THICKNESS SENSOR SYSTEM, is incorporated by reference in its entirety. Further details regarding slip ring assembly  600  may be found in U.S. Patent Application Publication No. 2014/0263541. 
     As discussed above, the interchangeable shaft assembly  200  can include a proximal portion which is fixably mounted to the handle assembly  14  and a distal portion which is rotatable about a longitudinal axis. The rotatable distal shaft portion can be rotated relative to the proximal portion about the slip ring assembly  600 , as discussed above. The distal connector flange  601  of the slip ring assembly  600  can be positioned within the rotatable distal shaft portion. Moreover, further to the above, the switch drum  500  can also be positioned within the rotatable distal shaft portion. When the rotatable distal shaft portion is rotated, the distal connector flange  601  and the switch drum  500  can be rotated synchronously with one another. In addition, the switch drum  500  can be rotated between a first position and a second position relative to the distal connector flange  601 . When the switch drum  500  is in its first position, the articulation drive system may be operably disengaged from the firing drive system and, thus, the operation of the firing drive system may not articulate the end effector  300  of the interchangeable shaft assembly  200 . When the switch drum  500  is in its second position, the articulation drive system may be operably engaged with the firing drive system and, thus, the operation of the firing drive system may articulate the end effector  300  of the interchangeable shaft assembly  200 . When the switch drum  500  is moved between its first position and its second position, the switch drum  500  is moved relative to distal connector flange  601 . In various instances, the interchangeable shaft assembly  200  can comprise at least one sensor configured to detect the position of the switch drum  500 . Turning now to  FIG.  9   , the distal connector flange  601  can comprise a magnetic field sensor  605 , for example, and the switch drum  500  can comprise a magnetic element, such as permanent magnet  505 , for example. The magnetic field sensor  605  can be configured to detect the position of the permanent magnet  505 . When the switch drum  500  is rotated between its first position and its second position, the permanent magnet  505  can move relative to the magnetic field sensor  605 . In various instances, magnetic field sensor  605  can detect changes in a magnetic field created when the permanent magnet  505  is moved. The magnetic field sensor  605  can be in signal communication with the shaft circuit board  610  and/or the circuit board  100  located in the handle, for example. Based on the signal from the magnetic field sensor  605 , a controller on the shaft circuit board  610  and/or the circuit board  100  located in the handle can determine whether the articulation drive system is engaged with or disengaged from the firing drive system. 
     Referring again to  FIG.  3   , the chassis  240  includes at least one, and preferably two, tapered attachment portions  244  formed thereon that are adapted to be received within corresponding dovetail slots  702  formed within a distal attachment flange  700  of the frame  20 . Each dovetail slot  702  may be tapered or, stated another way, be somewhat V-shaped to seatingly receive the tapered attachment portions  244  therein. As can be further seen in  FIG.  3   , a shaft attachment lug  226  is formed on the proximal end of the intermediate firing shaft  222 . As will be discussed in further detail below, when the interchangeable shaft assembly  200  is coupled to the handle assembly  14 , the shaft attachment lug  226  is received in a firing shaft attachment cradle  126  formed in the distal end  125  of the longitudinally movable drive member  120  as shown in  FIGS.  3  and  6   , for example. 
     Various shaft assemblies employ a latch system  710  for removably coupling the interchangeable shaft assembly  200  to the housing  12  and more specifically to the frame  20 . The proximally protruding lock lugs  714  each have a pivot lock lugs  716  formed thereon that are adapted to be received in corresponding holes  245  formed in the chassis  240 . Such arrangement facilitates pivotal attachment of the lock yoke  712  to the chassis  240 . The lock yoke  712  may include two proximally protruding lock lugs  714  that are configured for releasable engagement with corresponding lock detents or grooves  704  in the distal attachment flange  700  of the frame  20 . See  FIG.  3   . In various forms, the lock yoke  712  is biased in the proximal direction by spring or biasing member (not shown). Actuation of the lock yoke  712  may be accomplished by a latch button  722  that is slidably mounted on a latch actuator assembly  720  that is mounted to the chassis  240 . The latch button  722  may be biased in a proximal direction relative to the lock yoke  712 . As will be discussed in further detail below, the lock yoke  712  may be moved to an unlocked position by biasing the latch button the in distal direction which also causes the lock yoke  712  to pivot out of retaining engagement with the distal attachment flange  700  of the frame  20 . When the lock yoke  712  is in “retaining engagement” with the distal attachment flange  700  of the frame  20 , the pivot lock lugs  716  are retainingly seated within the corresponding lock detents or grooves  704  in the distal attachment flange  700 . 
     When employing an interchangeable shaft assembly that includes an end effector of the type described herein that is adapted to cut and fasten tissue, as well as other types of end effectors, it may be desirable to prevent inadvertent detachment of the interchangeable shaft assembly from the housing during actuation of the end effector. For example, in use the clinician may actuate the closure trigger  32  to grasp and manipulate the target tissue into a desired position. Once the target tissue is positioned within the end effector  300  in a desired orientation, the clinician may then fully actuate the closure trigger  32  to close the anvil  306  and clamp the target tissue in position for cutting and stapling. In that instance, the first drive system  30  has been fully actuated. After the target tissue has been clamped in the end effector  300 , it may be desirable to prevent the inadvertent detachment of the interchangeable shaft assembly  200  from the housing  12 . One form of the latch system  710  is configured to prevent such inadvertent detachment. 
     The lock yoke  712  includes at least one, and preferably two, lock hooks  718  that are adapted to contact lock lugs  256  that are formed on the closure shuttle  250 . Referring to  FIGS.  10  and  11   , when the closure shuttle  250  is in an unactuated position (i.e., the first closure drive system  30  is unactuated and the anvil  306  is open), the lock yoke  712  may be pivoted in a distal direction to unlock the interchangeable shaft assembly  200  from the housing  12 . When in that position, the lock hooks  718  do not contact the lock lugs  256  on the closure shuttle  250 . However, when the closure shuttle  250  is moved to an actuated position (i.e., the first closure drive system  30  is actuated and the anvil  306  is in the closed position), the lock yoke  712  is prevented from being pivoted to an unlocked position. See  FIGS.  12  and  13   . Stated another way, if the clinician were to attempt to pivot the lock yoke  712  to an unlocked position or, for example, the lock yoke  712  was in advertently bumped or contacted in a manner that might otherwise cause it to pivot distally, the lock hooks  718  on the lock yoke  712  will contact the lock lugs  256  on the closure shuttle  250  and prevent movement of the lock yoke  712  to an unlocked position. 
     Attachment of the interchangeable shaft assembly  200  to the handle assembly  14  will now be described with reference to  FIG.  3   . To commence the coupling process, the clinician may position the chassis  240  of the interchangeable shaft assembly  200  above or adjacent to the distal attachment flange  700  of the frame  20  such that the tapered attachment portions  244  formed on the chassis  240  are aligned with the dovetail slots  702  in the frame  20 . The clinician may then move the interchangeable shaft assembly  200  along an installation axis IA that is perpendicular to the shaft axis SA-SA to seat the tapered attachment portions  244  in “operable engagement” with the corresponding dovetail receiving slots  702 . In doing so, the shaft attachment lug  226  on the intermediate firing shaft  222  will also be seated in the firing shaft attachment cradle  126  in the longitudinally movable drive member  120  and the portions of the transverse attachment pin  37  on the second closure link  38  will be seated in the corresponding proximally-protruding hooks  252  in the closure shuttle  250 . As used herein, the term “operable engagement” in the context of two components means that the two components are sufficiently engaged with each other so that upon application of an actuation motion thereto, the components may carry out their intended action, function and/or procedure. 
     As discussed above, at least five systems of the interchangeable shaft assembly  200  can be operably coupled with at least five corresponding systems of the handle assembly  14 . A first system can comprise a frame system which couples and/or aligns the frame or spine of the interchangeable shaft assembly  200  with the frame  20  of the handle assembly  14 . Another system can comprise a closure drive system  30  which can operably connect the closure trigger  32  of the handle assembly  14  and the closure tube  260  and the anvil  306  of the interchangeable shaft assembly  200 . As outlined above, the closure shuttle  250  of the interchangeable shaft assembly  200  can be engaged with the transverse attachment pin  37  on the second closure link  38 . Another system can comprise the firing drive system  80  which can operably connect the firing trigger  130  of the handle assembly  14  with the intermediate firing shaft  222  of the interchangeable shaft assembly  200 . 
     As outlined above, the shaft attachment lug  226  can be operably connected with the firing shaft attachment cradle  126  of the longitudinally movable drive member  120 . Another system can comprise an electrical system which can signal to a controller in the handle assembly  14 , such as controller, for example, that a shaft assembly, such as the interchangeable shaft assembly  200 , for example, has been operably engaged with the handle assembly  14  and/or, two, conduct power and/or communication signals between the interchangeable shaft assembly  200  and the handle assembly  14 . For instance, the interchangeable shaft assembly  200  can include an electrical connector  1410  that is operably mounted to the shaft circuit board  610 . The electrical connector  1410  located on the shaft is configured for mating engagement with an electrical connector  1400  on the circuit board  100  located in the handle. Further details regaining the circuitry and control systems may be found in U.S. Patent Application Publication No. 20140263541. The fifth system may consist of the latching system for releasably locking the interchangeable shaft assembly  200  to the handle assembly  14 . 
     Referring to  FIG.  14   , a non-limiting form of the end effector  300  is illustrated. As described above, the end effector  300  may include the anvil  306  and the surgical staple cartridge  304 . In this non-limiting example, the anvil  306  is coupled to an elongated channel  198 . For example, apertures  199  can be defined in the elongated channel  198  which can receive pins  152  extending from the anvil  306  and allow the anvil  306  to pivot from an open position to a closed position relative to the elongated channel  198  and surgical staple cartridge  304 . In addition,  FIG.  14    shows a firing bar  172 , configured to longitudinally translate into the end effector  300 . The firing bar  172  may be constructed from one solid section, or in various examples, may include a laminate material comprising, for example, a stack of steel plates. A distally projecting end of the firing bar  172  can be attached to an E-beam  178  that can, among other things, assist in spacing the anvil  306  from a surgical staple cartridge  304  positioned in the elongated channel  198  when the anvil  306  is in a closed position. The E-beam  178  can also include a sharpened cutting edge  182  which can be used to sever tissue as the E-beam  178  is advanced distally by the firing bar  172 . In operation, the E-beam  178  can also actuate, or fire, the surgical staple cartridge  304 . The surgical staple cartridge  304  can include a molded cartridge body  194  that holds a plurality of staples  191  resting upon staple drivers  192  within respective upwardly open staple cavities  195 . A wedge sled  190  is driven distally by the E-beam  178 , sliding upon a cartridge tray  196  that holds together the various components of the surgical staple cartridge  304 . The wedge sled  190  upwardly cams the staple drivers  192  to force out the staples  191  into deforming contact with the anvil  306  while a cutting edge  182  of the E-beam  178  severs clamped tissue. 
     Further to the above, the E-beam  178  can include upper pins  180  which engage the anvil  306  during firing. The E-beam  178  can further include middle pins  184  and a bottom foot  186  which can engage various portions of the cartridge body  194 , cartridge tray  196  and elongated channel  198 . When a surgical staple cartridge  304  is positioned within the elongated channel  198 , a slot  193  defined in the cartridge body  194  can be aligned with a longitudinal slot  197  defined in the cartridge tray  196  and a slot  189  defined in the elongated channel  198 . In use, the E-beam  178  can slide through the aligned longitudinal slots  193 ,  197 , and  189  wherein, as indicated in  FIG.  14   , the bottom foot  186  of the E-beam  178  can engage a groove running along the bottom surface of elongated channel  198  along the length of slot  189 , the middle pins  184  can engage the top surfaces of cartridge tray  196  along the length of longitudinal slot  197 , and the upper pins  180  can engage the anvil  306 . In such circumstances, the E-beam  178  can space, or limit the relative movement between, the anvil  306  and the surgical staple cartridge  304  as the firing bar  172  is moved distally to fire the staples from the surgical staple cartridge  304  and/or incise the tissue captured between the anvil  306  and the surgical staple cartridge  304 . Thereafter, the firing bar  172  and the E-beam  178  can be retracted proximally allowing the anvil  306  to be opened to release the two stapled and severed tissue portions (not shown). 
     Having described a surgical instrument  10  ( FIGS.  1 - 14   ) in general terms, the description now turns to a detailed description of various electrical/electronic components of the surgical instrument  10 . Referring again to  FIGS.  2  and  3   , the handle assembly  14  can include an electrical connector  1400  comprising a plurality of electrical contacts. Turning now to  FIG.  15   , the electrical connector  1400  can comprise a first electrical contact  1401   a , a second electrical contact  1401   b , a third electrical contact  1401   c , a fourth electrical contact  1401   d , a fifth electrical contact  1401   e , and a sixth electrical contact  1401   f , for example. While the illustrated example utilizes six contacts, other examples are envisioned which may utilize more than six contacts or less than six contacts. 
     As illustrated in  FIG.  15   , the first electrical contact  1401   a  can be in electrical communication with a transistor  1408 , electrical contacts  1401   b - 1401   e  can be in electrical communication with a controller  1500 , and the sixth electrical contact  1401   f  can be in electrical communication with a ground. In certain circumstances, one or more of the electrical contacts  1401   b - 1401   e  may be in electrical communication with one or more output channels of the controller  1500  and can be energized, or have a voltage potential applied thereto, when the handle  1042  is in a powered state. In some circumstances, one or more of the electrical contacts  1401   b - 1401   e  may be in electrical communication with one or more input channels of the controller  1500  and, when the handle assembly  14  is in a powered state, the controller  1500  can be configured to detect when a voltage potential is applied to such electrical contacts. When a shaft assembly, such as the interchangeable shaft assembly  200 , for example, is assembled to the handle assembly  14 , the electrical contacts  1401   a - 1401   f  may not communicate with each other. When a shaft assembly is not assembled to the handle assembly  14 , however, the electrical contacts  1401   a - 1401   f  of the electrical connector  1400  may be exposed and, in some circumstances, one or more of the electrical contacts  1401   a - 1401   f  may be accidentally placed in electrical communication with each other. Such circumstances can arise when one or more of the electrical contacts  1401   a - 1401   f  come into contact with an electrically conductive material, for example. When this occurs, the controller  1500  can receive an erroneous input and/or the interchangeable shaft assembly  200  can receive an erroneous output, for example. To address this issue, in various circumstances, the handle assembly  14  may be unpowered when a shaft assembly, such as the interchangeable shaft assembly  200 , for example, is not attached to the handle assembly  14 . 
     In other circumstances, the handle  1042  can be powered when a shaft assembly, such as the interchangeable shaft assembly  200 , for example, is not attached thereto. In such circumstances, the controller  1500  can be configured to ignore inputs, or voltage potentials, applied to the contacts in electrical communication with the controller  1500 , i.e., electrical contacts  1401   b - 1401   e , for example, until a shaft assembly is attached to the handle assembly  14 . Even though the controller  1500  may be supplied with power to operate other functionalities of the handle assembly  14  in such circumstances, the handle assembly  14  may be in a powered-down state. In a way, the electrical connector  1400  may be in a powered-down state as voltage potentials applied to the electrical contacts  1401   b - 1401   e  may not affect the operation of the handle assembly  14 . The reader will appreciate that, even though electrical contacts  1401   b - 1401   e  may be in a powered-down state, the electrical contacts  1401   a  and  1401   f , which are not in electrical communication with the controller  1500 , may or may not be in a powered-down state. For instance, sixth electrical contact  1401   f  may remain in electrical communication with a ground regardless of whether the handle assembly  14  is in a powered-up or a powered-down state. 
     Furthermore, the transistor  1408 , and/or any other suitable arrangement of transistors, such as transistor  1412 , for example, and/or switches may be configured to control the supply of power from a power source  1404 , such as a battery, within the handle assembly  14 , for example, to the first electrical contact  1401   a  regardless of whether the handle assembly  14  is in a powered-up or a powered-down state. In various circumstances, the interchangeable shaft assembly  200 , for example, can be configured to change the state of the transistor  1408  when the interchangeable shaft assembly  200  is engaged with the handle assembly  14 . In certain circumstances, further to the below, a magnetic field sensor  1402  can be configured to switch the state of transistor  1412  which, as a result, can switch the state of transistor  1408  and ultimately supply power from power source  1404  to first electrical contact  1401   a . In this way, both the power circuits and the signal circuits to the electrical connector  1400  can be powered down when a shaft assembly is not installed to the handle assembly  14  and powered up when a shaft assembly is installed to the handle assembly  14 . 
     In various circumstances, referring again to  FIG.  15   , the handle assembly  14  can include the magnetic field sensor  1402 , for example, which can be configured to detect a detectable element, such as a magnetic element  1407  ( FIG.  3   ), for example, on a shaft assembly, such as the interchangeable shaft assembly  200 , for example, when the shaft assembly is coupled to the handle assembly  14 . The magnetic field sensor  1402  can be powered by a power source  1406 , such as a battery, for example, which can, in effect, amplify the detection signal of the magnetic field sensor  1402  and communicate with an input channel of the controller  1500  via the circuit illustrated in  FIG.  15   . Once the controller  1500  has a received an input indicating that a shaft assembly has been at least partially coupled to the handle assembly  14 , and that, as a result, the electrical contacts  1401   a - 1401   f  are no longer exposed, the controller  1500  can enter into its normal, or powered-up, operating state. In such an operating state, the controller  1500  will evaluate the signals transmitted to one or more of the electrical contacts  1401   b - 1401   e  from the shaft assembly and/or transmit signals to the shaft assembly through one or more of the electrical contacts  1401   b - 1401   e  in normal use thereof. In various circumstances, the interchangeable shaft assembly  200  may have to be fully seated before the magnetic field sensor  1402  can detect the magnetic element  1407 . While a magnetic field sensor  1402  can be utilized to detect the presence of the interchangeable shaft assembly  200 , any suitable system of sensors and/or switches can be utilized to detect whether a shaft assembly has been assembled to the handle assembly  14 , for example. In this way, further to the above, both the power circuits and the signal circuits to the electrical connector  1400  can be powered down when a shaft assembly is not installed to the handle assembly  14  and powered up when a shaft assembly is installed to the handle assembly  14 . 
     In various examples, as may be used throughout the present disclosure, any suitable magnetic field sensor may be employed to detect whether a shaft assembly has been assembled to the handle assembly  14 , for example. For example, the technologies used for magnetic field sensing include Hall effect sensor, search coil, fluxgate, optically pumped, nuclear precession, SQUID (superconducting quantum interference device—a very sensitive magnetometer used to measure extremely subtle magnetic fields, based on superconducting loops containing Josephson junctions), Hall-effect, anisotropic magnetoresistance, giant magnetoresistance, magnetic tunnel junctions, giant magnetoimpedance, magnetostrictive/piezoelectric composites, magnetodiode, magnetotransistor, fiber optic, magnetooptic, and microelectromechanical systems-based magnetic sensors, among others. 
     Referring to  FIG.  15   , the controller  1500  may generally comprise a processor (“microprocessor”) and one or more memory units operationally coupled to the processor. By executing instruction code stored in the memory, the processor may control various components of the surgical instrument, such as the motor, various drive systems, and/or a user display, for example. The controller  1500  may be implemented using integrated and/or discrete hardware elements, software elements, and/or a combination of both. Examples of integrated hardware elements may include processors, microprocessors, controllers, controllers, integrated circuits, application specific integrated circuits (ASIC), programmable logic devices (PLD), digital signal processors (DSP), field programmable gate arrays (FPGA), logic gates, registers, semiconductor devices, chips, microchips, chip sets, controllers, system-on-chip (SoC), and/or system-in-package (SIP). Examples of discrete hardware elements may include circuits and/or circuit elements such as logic gates, field effect transistors, bipolar transistors, resistors, capacitors, inductors, and/or relays. In certain instances, the controller  1500  may include a hybrid circuit comprising discrete and integrated circuit elements or components on one or more substrates, for example. 
     Referring to  FIG.  15   , the controller  1500  may be an LM4F230H5QR, available from Texas Instruments, for example. In certain instances, the Texas Instruments LM4F230H5QR is an ARM Cortex-M4F Processor Core comprising on-chip memory of 256 KB single-cycle flash memory, or other non-volatile memory, up to 40 MHz, a prefetch buffer to improve performance above 40 MHz, a 32 KB single-cycle serial random access memory (SRAM), internal read-only memory (ROM) loaded with StellarisWare® software, 2 KB electrically erasable programmable read-only memory (EEPROM), one or more pulse width modulation (PWM) modules, one or more quadrature encoder inputs (QEI) analog, one or more 12-bit Analog-to-Digital Converters (ADC) with 12 analog input channels, among other features that are readily available from the product datasheet. Other controllers may be readily substituted for use with the present disclosure. Accordingly, the present disclosure should not be limited in this context. 
     As discussed above, the handle assembly  14  and/or the interchangeable shaft assembly  200  can include systems and configurations configured to prevent, or at least reduce the possibility of, the contacts of the electrical connector  1400  located on the handle and/or the contacts of the electrical connector  1410  located on the shaft from becoming shorted out when the interchangeable shaft assembly  200  is not assembled, or completely assembled, to the handle assembly  14 . Referring to  FIG.  3   , the electrical connector  1400  located on the handle can be at least partially recessed within a cavity  1409  defined in the frame  20 . The six electrical contacts  1401   a - 1401   f  of the electrical connector  1400  can be completely recessed within the cavity  1409 . Such arrangements can reduce the possibility of an object accidentally contacting one or more of the electrical contacts  1401   a - 1401   f . Similarly, the electrical connector  1410  located on the shaft can be positioned within a recess defined in the chassis  240  which can reduce the possibility of an object accidentally contacting one or more of the electrical contacts  1411   a - 1411   f  of the electrical connector  1410  located on the shaft. With regard to the particular example depicted in  FIG.  3   , the electrical contacts  1411   a - 1411   f  located on the shaft can comprise male contacts. In at least one example, each of the electrical contacts  1411   a - 1411   f  located in the shaft can comprise a flexible projection extending therefrom which can be configured to engage an electrical contact  1401   a - 1401   f  located on the handle, for example. The electrical contacts  1401   a - 1401   f  located on the handle can comprise female contacts. In at least one example, each electrical contact  1401   a - 1401   f  located on the handle can comprise a flat surface, for example, against which the male electrical contacts  1401   a - 1401   f  located on the shaft can wipe, or slide, against and maintain an electrically conductive interface therebetween. In various instances, the direction in which the interchangeable shaft assembly  200  is assembled to the handle assembly  14  can be parallel to, or at least substantially parallel to, the electrical contacts  1401   a - 1401   f  located on the handle such that the electrical contacts  1411   a - 1411   f  located on the shaft slide against the electrical contacts  1401   a - 1401   f  located on the handle when the interchangeable shaft assembly  200  is assembled to the handle assembly  14 . In various alternative examples, the electrical contacts  1401   a - 1401   f  located in the handle can comprise male contacts and the electrical contacts  1411   a - 1411   f  located on the shaft can comprise female contacts. In certain alternative examples, the electrical contacts  1401   a - 1401   f  located on the handle and the electrical contacts  1411   a - 1411   f  located on the shaft can comprise any suitable arrangement of contacts. 
     In various instances, the handle assembly  14  can comprise a connector guard configured to at least partially cover the electrical connector  1400  located on the handle and/or a connector guard configured to at least partially cover the electrical connector  1410  located on the shaft. A connector guard can prevent, or at least reduce the possibility of, an object accidentally touching the contacts of an electrical connector when the shaft assembly is not assembled to, or only partially assembled to, the handle A connector guard can be movable. For instance, the connector guard can be moved between a guarded position in which it at least partially guards a connector and an unguarded position in which it does not guard, or at least guards less of, the connector. In at least one example, a connector guard can be displaced as the shaft assembly is being assembled to the handle. For instance, if the handle comprises a handle connector guard, the shaft assembly can contact and displace the handle connector guard as the shaft assembly is being assembled to the handle. Similarly, if the shaft assembly comprises a shaft connector guard, the handle can contact and displace the shaft connector guard as the shaft assembly is being assembled to the handle. In various instances, a connector guard can comprise a door, for example. In at least one instance, the door can comprise a beveled surface which, when contacted by the handle or shaft, can facilitate the displacement of the door in a certain direction. In various instances, the connector guard can be translated and/or rotated, for example. In certain instances, a connector guard can comprise at least one film which covers the contacts of an electrical connector. When the shaft assembly is assembled to the handle, the film can become ruptured. In at least one instance, the male contacts of a connector can penetrate the film before engaging the corresponding contacts positioned underneath the film. 
     As described above, the surgical instrument can include a system which can selectively power-up, or activate, the contacts of an electrical connector, such as the electrical connector  1400 , for example. In various instances, the contacts can be transitioned between an unactivated condition and an activated condition. In certain instances, the contacts can be transitioned between a monitored condition, a deactivated condition, and an activated condition. For instance, the controller  1500 , for example, can monitor the electrical contacts  1401   a - 1401   f  when a shaft assembly has not been assembled to the handle assembly  14  to determine whether one or more of the electrical contacts  1401   a - 1401   f  may have been shorted. The controller  1500  can be configured to apply a low voltage potential to each of the electrical contacts  1401   a - 1401   f  and assess whether only a minimal resistance is present at each of the contacts. Such an operating state can comprise the monitored condition. In the event that the resistance detected at a contact is high, or above a threshold resistance, the controller  1500  can deactivate that contact, more than one contact, or, alternatively, all of the contacts. Such an operating state can comprise the deactivated condition. If a shaft assembly is assembled to the handle assembly  14  and it is detected by the controller  1500 , as discussed above, the controller  1500  can increase the voltage potential to the electrical contacts  1401   a - 1401   f . Such an operating state can comprise the activated condition. 
     The various shaft assemblies disclosed herein may employ sensors and various other components that require electrical communication with the controller in the housing. These shaft assemblies generally are configured to be able to rotate relative to the housing necessitating a connection that facilitates such electrical communication between two or more components that may rotate relative to each other. When employing end effectors of the types disclosed herein, the connector arrangements must be relatively robust in nature while also being somewhat compact to fit into the shaft assembly connector portion. 
     Turning now to  FIGS.  16 A and  16 B , where one example of a segmented circuit  2000  comprising a plurality of circuit segments  2002   a - 2002   g  is illustrated. The segmented circuit  2000  comprising the plurality of circuit segments  2002   a - 2002   g  is configured to control a powered surgical instrument, such as, for example, the surgical instrument  10  illustrated in  FIGS.  1 - 13   , without limitation. The plurality of circuit segments  2002   a - 2002   g  is configured to control one or more operations of the powered surgical instrument  10 . A safety processor segment  2002   a  (Segment  1 ) comprises a safety processor  2004 . A primary processor segment  2002   b  (Segment  2 ) comprises a primary processor  2006 . The safety processor  2004  and/or the primary processor  2006  are configured to interact with one or more additional circuit segments  2002   c - 2002   g  to control operation of the powered surgical instrument  10 . The primary processor  2006  comprises a plurality of inputs coupled to, for example, one or more circuit segments  2002   c - 2002   g , a battery  2008 , and/or a plurality of switches  2058   a - 2070 . The segmented circuit  2000  may be implemented by any suitable circuit, such as, for example, a printed circuit board assembly (PCBA) within the powered surgical instrument  10 . It should be understood that the term processor as used herein includes any microprocessor, processors, controller, controllers, or other basic computing device that incorporates the functions of a computer&#39;s central processing unit (CPU) on an integrated circuit or at most a few integrated circuits. The processor is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and provides results as output. It is an example of sequential digital logic, as it has internal memory. Processors operate on numbers and symbols represented in the binary numeral system. 
     In one aspect, the primary processor  2006  may be any single core or multicore processor such as those known under the trade name ARM Cortex by Texas Instruments. In one example, the safety processor  2004  may be a safety controller platform comprising two controller-based families such as TMS570 and RM4x known under the trade name Hercules ARM Cortex R4, also by Texas Instruments. Nevertheless, other suitable substitutes for controllers and safety processor may be employed, without limitation. In one example, the safety processor  2004  may be configured specifically for IEC 61508 and ISO 26262 safety critical applications, among others, to provide advanced integrated safety features while delivering scalable performance, connectivity, and memory options. In certain instances, the primary processor  2006  may be a single core or multicore controller LM4F230H5QR as described in connection with  FIGS.  14 - 17 B . 
     In one aspect, the segmented circuit  2000  comprises an acceleration segment  2002   c  (Segment  3 ). The acceleration segment  2002   c  comprises an accelerometer  2022 . The accelerometer  2022  is configured to detect movement or acceleration of the powered surgical instrument  10 . In some examples, input from the accelerometer  2022  is used, for example, to transition to and from a sleep mode, identify an orientation of the powered surgical instrument, and/or identify when the surgical instrument has been dropped. In some examples, the acceleration segment  2002   c  is coupled to the safety processor  2004  and/or the primary processor  2006 . 
     In one aspect, the segmented circuit  2000  comprises a display segment  2002   d  (Segment  4 ). The display segment  2002   d  comprises a display connector  2024  coupled to the primary processor  2006 . The display connector  2024  couples the primary processor  2006  to a display  2028  through one or more integrated circuit drivers of the display  2026 . The integrated circuit drivers of the display  2026  may be integrated with the display  2028  and/or may be located separately from the display  2028 . The display  2028  may comprise any suitable display, such as, for example, an organic light-emitting diode (OLED) display, a liquid-crystal display (LCD), and/or any other suitable display. In some examples, the display segment  2002   d  is coupled to the safety processor  2004 . 
     In some aspects, the segmented circuit  2000  comprises a shaft segment  2002   e  (Segment  5 ). The shaft segment  2002   e  comprises one or more controls for an interchangeable shaft assembly  200  ( FIG.  1   ) coupled to the surgical instrument  10  and/or one or more controls for an end effector  300  coupled to the interchangeable shaft assembly  200  ( FIG.  1   ). The shaft segment  2002   e  comprises a shaft connector  2030  configured to couple the primary processor  2006  to a shaft PCBA  2031 . The shaft PCBA  2031  comprises a first articulation switch  2036 , a second articulation switch  2032 , and a shaft PCBA EEPROM 2034. In some examples, the shaft PCBA EEPROM 2034 comprises one or more parameters, routines, and/or programs specific to the interchangeable shaft assembly  200  and/or the shaft PCBA  2031 . The shaft PCBA  2031  may be coupled to the interchangeable shaft assembly  200  and/or integral with the surgical instrument  10 . In some examples, the shaft segment  2002   e  comprises a second shaft EEPROM 2038. The second shaft EEPROM 2038 comprises a plurality of algorithms, routines, parameters, and/or other data corresponding to one or more shaft assemblies  200  and/or end effectors  300  which may be interfaced with the powered surgical instrument  10 . 
     In some aspects, the segmented circuit  2000  comprises a position encoder segment  2002   f  (Segment  6 ). The position encoder segment  2002   f  comprises one or more magnetic angle rotary position encoders  2040   a - 2040   b . The one or more magnetic angle rotary position encoders  2040   a - 2040   b  are configured to identify the rotational position of a motor  2048 , an interchangeable shaft assembly  200  ( FIG.  1   ), and/or an end effector  300  of the surgical instrument  10 . In some examples, the magnetic angle rotary position encoders  2040   a - 2040   b  may be coupled to the safety processor  2004  and/or the primary processor  2006 . 
     In some aspects, the segmented circuit  2000  comprises a motor circuit segment  2002   g  (Segment  7 ). The motor circuit segment  2002   g  comprises a motor  2048  configured to control one or more movements of the powered surgical instrument  10 . The motor  2048  is coupled to the primary processor  2006  by an H-Bridge driver  2042  and one or more H-bridge field-effect transistors  2044  (FETs). The H-bridge FETs  2044  are coupled to the safety processor  2004 . A motor current sensor  2046  is coupled in series with the motor  2048  to measure the current draw of the motor  2048 . The motor current sensor  2046  is in signal communication with the primary processor  2006  and/or the safety processor  2004 . In some examples, the motor  2048  is coupled to a motor electromagnetic interference (EMI) filter  2050 . 
     In some aspects, the segmented circuit  2000  comprises a power segment  2002   h  (Segment  8 ). A battery  2008  is coupled to the safety processor  2004 , the primary processor  2006 , and one or more of the additional circuit segments  2002   c - 2002   g . The battery  2008  is coupled to the segmented circuit  2000  by a battery connector  2010  and a current sensor  2012 . The current sensor  2012  is configured to measure the total current draw of the segmented circuit  2000 . In some examples, one or more voltage converters  2014   a ,  2014   b ,  2016  are configured to provide predetermined voltage values to one or more circuit segments  2002   a - 2002   g . For example, in some examples, the segmented circuit  2000  may comprise 3.3V voltage converters  2014   a - 2014   b  and/or 5V voltage converters  2016 . A boost converter  2018  is configured to provide a boost voltage up to a predetermined amount, such as, for example, up to 13V. The boost converter  2018  is configured to provide additional voltage and/or current during power intensive operations and prevent brownout or low-power conditions. 
     In some aspects, the safety processor segment  2002   a  comprises a motor power switch  2020 . The motor power switch  2020  is coupled between the power segment  2002   h  and the motor circuit segment  2002   g . The safety processor segment  2002   a  is configured to interrupt power to the motor circuit segment  2002   g  when an error or fault condition is detected by the safety processor  2004  and/or the primary processor  2006  as discussed in more detail herein. Although the circuit segments  2002   a - 2002   g  are illustrated with all components of the circuit segments  2002   a - 2002   h  located in physical proximity, one skilled in the art will recognize that a circuit segment  2002   a - 2002   h  may comprise components physically and/or electrically separate from other components of the same circuit segment  2002   a - 2002   g . In some examples, one or more components may be shared between two or more circuit segments  2002   a - 2002   g.    
     In some aspects, a plurality of switches  2056 - 2070  are coupled to the safety processor  2004  and/or the primary processor  2006 . The plurality of switches  2056 - 2070  may be configured to control one or more operations of the surgical instrument  10 , control one or more operations of the segmented circuit  2000 , and/or indicate a status of the surgical instrument  10 . For example, a bail-out door switch  2056  is configured to indicate the status of a bail-out door. A plurality of articulation switches, such as, for example, a left side articulation left switch  2058   a , a left side articulation right switch  2060   a , a left side articulation center switch  2062   a , a right side articulation left switch  2058   b , a right side articulation right switch  2060   b , and a right side articulation center switch  2062   b  are configured to control articulation of a shaft assembly  200  and/or an end effector  300 . A left side reverse switch  2064   a  and a right side reverse switch  2064   b  are coupled to the primary processor  2006 . In some examples, the left side switches comprising the left side articulation left switch  2058   a , the left side articulation right switch  2060   a , the left side articulation center switch  2062   a , and the left side reverse switch  2064   a  are coupled to the primary processor  2006  by a left flex connector  2072   a . The right side switches comprising the right side articulation left switch  2058   b , the right side articulation right switch  2060   b , the right side articulation center switch  2062   b , and the right side reverse switch  2064   b  are coupled to the primary processor  2006  by a right flex connector  2072   b . In some examples, a firing switch  2066 , a clamp release switch  2068 , and a shaft engaged switch  2070  are coupled to the primary processor  2006 . 
     In some aspects, the plurality of switches  2056 - 2070  may comprise, for example, a plurality of handle controls mounted to a handle of the surgical instrument  10 , a plurality of indicator switches, and/or any combination thereof. In various examples, the plurality of switches  2056 - 2070  allow a surgeon to manipulate the surgical instrument, provide feedback to the segmented circuit  2000  regarding the position and/or operation of the surgical instrument, and/or indicate unsafe operation of the surgical instrument  10 . In some examples, additional or fewer switches may be coupled to the segmented circuit  2000 , one or more of the switches  2056 - 2070  may be combined into a single switch, and/or expanded to multiple switches. For example, in one example, one or more of the left side and/or right side articulation switches  2058   a - 2064   b  may be combined into a single multi-position switch. 
     In one aspect, the safety processor  2004  is configured to implement a watchdog function, among other safety operations. The safety processor  2004  and the primary processor  2006  of the segmented circuit  2000  are in signal communication. A processor alive heartbeat signal is provided at output  2097 . The acceleration segment  2002   c  comprises an accelerometer  2022  configured to monitor movement of the surgical instrument  10 . In various examples, the accelerometer  2022  may be a single, double, or triple axis accelerometer. The accelerometer  2022  may be employed to measures proper acceleration that is not necessarily the coordinate acceleration (rate of change of velocity). Instead, the accelerometer sees the acceleration associated with the phenomenon of weight experienced by a test mass at rest in the frame of reference of the accelerometer  2022 . For example, the accelerometer  2022  at rest on the surface of the earth will measure an acceleration g=9.8 m/s 2  (gravity) straight upwards, due to its weight. Another type of acceleration that accelerometer  2022  can measure is g-force acceleration. In various other examples, the accelerometer  2022  may comprise a single, double, or triple axis accelerometer. Further, the acceleration segment  2002   c  may comprise one or more inertial sensors to detect and measure acceleration, tilt, shock, vibration, rotation, and multiple degrees-of-freedom (DoF). A suitable inertial sensor may comprise an accelerometer (single, double, or triple axis), a magnetometer to measure a magnetic field in space such as the earth&#39;s magnetic field, and/or a gyroscope to measure angular velocity. 
     In one aspect, the safety processor  2004  is configured to implement a watchdog function with respect to one or more circuit segments  2002   c - 2002   h , such as, for example, the motor circuit segment  2002   g . In this regards, the safety processor  2004  employs the watchdog function to detect and recover from malfunctions of the primary processor  2006 . During normal operation, the safety processor  2004  monitors for hardware faults or program errors of the primary processor  2006  and to initiate corrective action or actions. The corrective actions may include placing the primary processor  2006  in a safe state and restoring normal system operation. In one example, the safety processor  2004  is coupled to at least a first sensor. The first sensor measures a first property of the surgical instrument  10  ( FIGS.  1 - 4   ). In some examples, the safety processor  2004  is configured to compare the measured property of the surgical instrument  10  to a predetermined value. For example, in one example, a magnetic angle rotary position encoder  2040   a  is coupled to the safety processor  2004 . The magnetic angle rotary position encoder  2040   a  provides motor speed and position information to the safety processor  2004 . The safety processor  2004  monitors the magnetic angle rotary position encoder  2040   a  and compares the value to a maximum speed and/or position value and prevents operation of the motor  2048  above the predetermined values. In some examples, the predetermined values are calculated based on real-time speed and/or position of the motor  2048 , calculated from values supplied by a second magnetic angle rotary position encoder  2040   b  in communication with the primary processor  2006 , and/or provided to the safety processor  2004  from, for example, a memory module coupled to the safety processor  2004 . 
     In some aspects, a second sensor is coupled to the primary processor  2006 . The second sensor is configured to measure the first physical property. The safety processor  2004  and the primary processor  2006  are configured to provide a signal indicative of the value of the first sensor and the second sensor respectively. When either the safety processor  2004  or the primary processor  2006  indicates a value outside of an acceptable range, the segmented circuit  2000  prevents operation of at least one of the circuit segments  2002   c - 2002   h , such as, for example, the motor circuit segment  2002   g . For example, in the example illustrated in  FIGS.  16 A and  16 B , the safety processor  2004  is coupled to a first magnetic angle rotary position encoder  2040   a  and the primary processor  2006  is coupled to a second magnetic angle rotary position encoder  2040   b . The magnetic angle rotary position encoders  2040   a ,  2040   b  may comprise any suitable motor position sensor, such as, for example, a magnetic angle rotary input comprising a sine and cosine output. The magnetic angle rotary position encoders  2040   a ,  2040   b  provide respective signals to the safety processor  2004  and the primary processor  2006  indicative of the position of the motor  2048 . 
     The safety processor  2004  and the primary processor  2006  generate an activation signal when the values of the first magnetic angle rotary position encoder  2040   a  and the second magnetic angle rotary position encoder  2040   b  are within a predetermined range. When either the primary processor  2006  or the safety processor  2004  to detect a value outside of the predetermined range, the activation signal is terminated and operation of at least one of the circuit segments  2002   c - 2002   h , such as, for example, the motor circuit segment  2002   g , is interrupted and/or prevented. For example, in some examples, the activation signal from the primary processor  2006  and the activation signal from the safety processor  2004  are coupled to an AND gate. The AND gate is coupled to a motor power switch  2020 . The AND gate maintains the motor power switch  2020  in a closed, or on, position when the activation signal from both the safety processor  2004  and the primary processor  2006  are high, indicating a value of the magnetic angle rotary position encoders  2040   a ,  2040   b  within the predetermined range. When either of the magnetic angle rotary position encoders  2040   a ,  2040   b  detect a value outside of the predetermined range, the activation signal from that magnetic angle rotary position encoder  2040   a ,  2040   b  is set low, and the output of the AND gate is set low, opening the motor power switch  2020 . In some examples, the value of the first magnetic angle rotary position encoder  2040   a  and the second magnetic angle rotary position encoder  2040   b  is compared, for example, by the safety processor  2004  and/or the primary processor  2006 . When the values of the first sensor and the second sensor are different, the safety processor  2004  and/or the primary processor  2006  may prevent operation of the motor circuit segment  2002   g.    
     In some aspects, the safety processor  2004  receives a signal indicative of the value of the second magnetic angle rotary position encoder  2040   b  and compares the second sensor value to the first sensor value. For example, in one aspect, the safety processor  2004  is coupled directly to a first magnetic angle rotary position encoder  2040   a . A second magnetic angle rotary position encoder  2040   b  is coupled to a primary processor  2006 , which provides the second magnetic angle rotary position encoder  2040   b  value to the safety processor  2004 , and/or coupled directly to the safety processor  2004 . The safety processor  2004  compares the value of the first magnetic angle rotary position encoder  2040  to the value of the second magnetic angle rotary position encoder  2040   b . When the safety processor  2004  detects a mismatch between the first magnetic angle rotary position encoder  2040   a  and the second magnetic angle rotary position encoder  2040   b , the safety processor  2004  may interrupt operation of the motor circuit segment  2002   g , for example, by cutting power to the motor circuit segment  2002   g.    
     In some aspects, the safety processor  2004  and/or the primary processor  2006  is coupled to a first magnetic angle rotary position encoder  2040   a  configured to measure a first property of a surgical instrument and a second magnetic angle rotary position encoder  2040   b  configured to measure a second property of the surgical instrument. The first property and the second property comprise a predetermined relationship when the surgical instrument is operating normally. The safety processor  2004  monitors the first property and the second property. When a value of the first property and/or the second property inconsistent with the predetermined relationship is detected, a fault occurs. When a fault occurs, the safety processor  2004  takes at least one action, such as, for example, preventing operation of at least one of the circuit segments, executing a predetermined operation, and/or resetting the primary processor  2006 . For example, the safety processor  2004  may open the motor power switch  2020  to cut power to the motor circuit segment  2002   g  when a fault is detected. 
     In one aspect, the safety processor  2004  is configured to execute an independent control algorithm. In operation, the safety processor  2004  monitors the segmented circuit  2000  and is configured to control and/or override signals from other circuit components, such as, for example, the primary processor  2006 , independently. The safety processor  2004  may execute a preprogrammed algorithm and/or may be updated or programmed on the fly during operation based on one or more actions and/or positions of the surgical instrument  10 . For example, in one example, the safety processor  2004  is reprogrammed with new parameters and/or safety algorithms each time a new shaft and/or end effector is coupled to the surgical instrument  10 . In some examples, one or more safety values stored by the safety processor  2004  are duplicated by the primary processor  2006 . Two-way error detection is performed to ensure values and/or parameters stored by either of the safety processor  2004  or primary processor  2006  are correct. 
     In some aspects, the safety processor  2004  and the primary processor  2006  implement a redundant safety check. The safety processor  2004  and the primary processor  2006  provide periodic signals indicating normal operation. For example, during operation, the safety processor  2004  may indicate to the primary processor  2006  that the safety processor  2004  is executing code and operating normally. The primary processor  2006  may, likewise, indicate to the safety processor  2004  that the primary processor  2006  is executing code and operating normally. In some examples, communication between the safety processor  2004  and the primary processor  2006  occurs at a predetermined interval. The predetermined interval may be constant or may be variable based on the circuit state and/or operation of the surgical instrument  10 . 
       FIGS.  17 A and  17 B  illustrate another aspect of a segmented circuit  3000  configured to control the powered surgical instrument  10 , illustrated in  FIGS.  1 - 14   . As shown in  FIGS.  14 ,  17 B , the handle assembly  14  may include an electric motor  3014  which can be controlled by a motor driver  3015  and can be employed by the firing system of the surgical instrument  10 . In various forms, the electric motor  3014  may be a DC brushed driving motor having a maximum rotation of, approximately, 25,000 RPM, for example. In other arrangements, the electric motor  3014  may include a brushless motor, a cordless motor, a synchronous motor, a stepper motor, or any other suitable electric motor. In certain circumstances, the motor driver  3015  may comprise an H-Bridge FETs  3019 , as illustrated in  FIGS.  17 A and  17 B , for example. The electric motor  3014  can be powered by a power assembly  3006 , which can be releasably mounted to the handle assembly  14 . The power assembly  3006  is configured to supply control power to the surgical instrument  10 . The power assembly  3006  may comprise a battery which may include a number of battery cells connected in series that can be used as the power source to power the surgical instrument  10 . In such configuration, the power assembly  3006  may be referred to as a battery pack. In certain circumstances, the battery cells of the power assembly  3006  may be replaceable and/or rechargeable. In at least one example, the battery cells can be Lithium-Ion batteries which can be separably couplable to the power assembly  3006 . 
     Examples of drive systems and closure systems that are suitable for use with the surgical instrument  10  are disclosed in U.S. Patent Application Publication No. 2014/0263539, entitled CONTROL SYSTEMS FOR SURGICAL INSTRUMENTS, which is incorporated herein by reference herein in its entirety. For example, the electric motor  3014  can include a rotatable shaft (not shown) that may operably interface with a gear reducer assembly that can be mounted in meshing engagement with a set, or rack, of drive teeth on a longitudinally-movable drive member. In use, a voltage polarity provided by the battery can operate the electric motor  3014  to drive the longitudinally-movable drive member to effectuate the end effector  300 . For example, the electric motor  3014  can be configured to drive the longitudinally-movable drive member to advance a firing mechanism to fire staples into tissue captured by the end effector  300  from a staple cartridge assembled with the end effector  300  and/or advance a cutting member to cut tissue captured by the end effector  300 , for example. 
     As illustrated in  FIGS.  17 A and  17 B  and as described below in greater detail, the power assembly  3006  may include a power management controller which can be configured to modulate the power output of the power assembly  3006  to deliver a first power output to power the electric motor  3014  to advance the cutting member while the interchangeable shaft assembly  200  is coupled to the handle assembly  14  ( FIG.  1   ) and to deliver a second power output to power the electric motor  3014  to advance the cutting member while the interchangeable shaft assembly  200  is coupled to the handle assembly  14 , for example. Such modulation can be beneficial in avoiding transmission of excessive power to the electric motor  3014  beyond the requirements of an interchangeable shaft assembly that is coupled to the handle assembly  14 . 
     In certain circumstances, the interface  3024  can facilitate transmission of the one or more communication signals between the power management controller  3016  and the shaft assembly controller  3022  by routing such communication signals through a main controller  3017  residing in the handle assembly  14  ( FIG.  1   ), for example. In other circumstances, the interface  3024  can facilitate a direct line of communication between the power management controller  3016  and the shaft assembly controller  3022  through the handle assembly  14  while the interchangeable shaft assembly  200  ( FIG.  1   ) and the power assembly  3006  are coupled to the handle assembly  14 . 
     In one instance, the main controller  3017  may be any single core or multicore processor such as those known under the trade name ARM Cortex by Texas Instruments. In one instance, the surgical instrument  10  ( FIGS.  1 - 4   ) may comprise a power management controller  3016  such as, for example, a safety controller platform comprising two controller-based families such as TMS570 and RM4x known under the trade name Hercules ARM Cortex R4, also by Texas Instruments. Nevertheless, other suitable substitutes for controllers and safety processor may be employed, without limitation. In one instance, the safety processor  2004  ( FIG.  16   a   ) may be configured specifically for IEC 61508 and ISO 26262 safety critical applications, among others, to provide advanced integrated safety features while delivering scalable performance, connectivity, and memory options. 
     In certain instances, the main controller  3017  may be a single core or multicore controller LM4F230H5QR as described in connection with  FIGS.  15 - 17 B . 
       FIG.  18    is a block diagram the surgical instrument of  FIG.  1    illustrating interfaces between the handle assembly  14  ( FIG.  1   ) and the power assembly and between the handle assembly  14  and the interchangeable shaft assembly. As shown in  FIG.  18   , the power assembly  3006  may include a power management circuit  3034  which may comprise the power management controller  3016 , a power modulator  3038 , and a current sense circuit  3036 . The power management circuit  3034  can be configured to modulate power output of the battery  3007  based on the power requirements of the interchangeable shaft assembly  200  ( FIG.  1   ) while the interchangeable shaft assembly  200  and the power assembly  3006  are coupled to the handle assembly  14 . For example, the power management controller  3016  can be programmed to control the power modulator  3038  of the power output of the power assembly  3006  and the current sense circuit  3036  can be employed to monitor power output of the power assembly  3006  to provide feedback to the power management controller  3016  about the power output of the battery  3007  so that the power management controller  3016  may adjust the power output of the power assembly  3006  to maintain a desired output. 
     It is noteworthy that the power management controller  3016  and/or the shaft assembly controller  3022  each may comprise one or more processors and/or memory units which may store a number of software modules. Although certain modules and/or blocks of the surgical instrument  10  ( FIG.  1   ) may be described by way of example, it can be appreciated that a greater or lesser number of modules and/or blocks may be used. Further, although various instances may be described in terms of modules and/or blocks to facilitate description, such modules and/or blocks may be implemented by one or more hardware components, e.g., processors, Digital Signal Processors (DSPs), Programmable Logic Devices (PLDs), Application Specific Integrated Circuits (ASICs), circuits, registers and/or software components, e.g., programs, subroutines, logic and/or combinations of hardware and software components. 
     In certain instances, the surgical instrument  10  ( FIGS.  1 - 4   ) may comprise an output device  3042  which may include one or more devices for providing a sensory feedback to a user. Such devices may comprise, for example, visual feedback devices (e.g., an LCD display screen, LED indicators), audio feedback devices (e.g., a speaker, a buzzer) or tactile feedback devices (e.g., haptic actuators). In certain circumstances, the output device  3042  may comprise a display  3043  which may be included in the handle assembly  14  ( FIG.  1   ). The shaft assembly controller  3022  and/or the power management controller  3016  can provide feedback to a user of the surgical instrument  10  through the output device  3042 . The interface  3024  can be configured to connect the shaft assembly controller  3022  and/or the power management controller  3016  to the output device  3042 . The reader will appreciate that the output device  3042  can instead be integrated with the power assembly  3006 . In such circumstances, communication between the output device  3042  and the shaft assembly controller  3022  may be accomplished through the interface  3024  while the interchangeable shaft assembly  200  is coupled to the handle assembly  14 . 
     Having described a surgical instrument  10  ( FIGS.  1 - 4   ) and one or more segmented circuit  2000 ,  3000  for controlling the operation thereof, the disclosure now turns to various specific configurations of the surgical instrument  10  and a segmented circuit  2000  (or  3000 ). 
     In various aspects the present disclosure provides techniques for data storage and usage. In one aspect, data storage and usage is based on multiple levels of action thresholds. Such thresholds include upper and lower ultimate threshold limits, ultimate threshold that shuts down motor or activates return is current, pressure, firing load, torque is exceeded, and alternatively, while running within the limits the device automatically compensates for loading of the motor. 
     In one aspect, the surgical instrument  10  (described in connection with  FIGS.  1 - 18   ) can be configured to monitor upper and lower ultimate threshold limits to maintain minimum and maximum closure clamp loads within acceptable limits. If a minimum is not achieved the surgical instrument  10  cannot start or if it drops below minimum a user action is required. If the clamp load is at a suitable level but drops under minimum during firing, the surgical instrument  10  can adjust the speed of the motor or warn the user. If the minimum limit is breached during operation the unit could give a warning that the firing may not be completely as anticipated. The surgical instrument  10  also can be configured to monitor when the battery voltage drops below the lower ultimate limit the remaining battery power is only direct able towards returning the device to the I-beam parked state. The opening force on the anvil can be employed to sense jams in the end effector. Alternatively, the surgical instrument  10  can be configured to monitor when the motor current goes up or the related speed goes down, then the motor control increases pulse width or frequency modulation to keep speed constant. 
     In another aspect, the surgical instrument  10  can ( FIG.  1   ) be configured to detect an ultimate threshold of current draw, pressure, firing load, torque such that when any of these thresholds are exceeded, the surgical instrument  10  shuts down the motor or causes the motor to return the knife to a pre-fired position. A secondary threshold, which is less than the ultimate threshold, may be employed to alter the motor control program to accommodate changes in conditions by changing the motor control parameters. A marginal threshold can be configured as a step function or a ramp function based on a proportionate response to another counter or input. For example, in the case of sterilization, no changes between 0-200 sterilization cycles, slow motor 1% per use from 201-400 sterilization cycles, and prevent use over 400 sterilization cycles. The speed of the motor also can be varied based on tissue gap and current draw. 
     There are many parameters that could influence the ideal function of a powered reusable stapler device. Most of these parameters have an ultimate maximum and/or minimum threshold beyond which the device should not be operated. Nevertheless, there are also marginal limits that may influence the functional operation of the device. These multiple limits, from multiple parameters may provide an overlying and cumulative effect on the operations program of the device. 
     Accordingly, the present disclosure relates to surgical instruments and, in various circumstances, to surgical stapling and cutting instruments and staple cartridges therefor that are designed to staple and cut tissue. 
     Efficient performance of an electromechanical device depends on various factors. One is the operational envelope, i.e., range of parameters, conditions and events in which the device carries out its intended functions. For example, for a device powered by a motor driven by electrical current, there may be an operational region above a certain electrical current threshold where the device runs more inefficiently than desired. Put another way, there may be an upper “speed limit” above which there is decreasing efficiency. Such an upper threshold may have value in preventing substantial inefficiencies or even device degradation. 
     There may be thresholds within an operational envelope, however, that may form regions exploitable to enhance efficiency within operational states. In other words, there may be regions where the device can adjust and perform better within a defined operational envelope (or sub-envelope). Such a region can be one between a marginal threshold and an ultimate threshold. In addition, these regions may comprise “sweet spots” or a predetermined optional range or point. These regions also may comprise a large range within which performance is judged to be adequate. 
     An ultimate threshold can be defined, above which or below which an action or actions could be taken (or refrained from being taken) such as stopping the device. In addition, a marginal threshold or thresholds can be defined, above which or below which an action or actions could be taken (or refrained from being taken). By way of non-limiting example, a marginal threshold can be set to define where the current draw of the motor exceeds 75% of an ultimate threshold. Exceeding the marginal threshold can result, for example, in the device&#39;s beginning to slow motor speed at an increasing rate as it continues to climb toward the ultimate threshold. 
     Various mechanisms can be employed to carry out the adjustment(s) taken as a result of exceeding a threshold. For example, the adjustment can reflect a step function. It can also reflect a ramped function. Other functions can be utilized. 
     In various aspects, to enhance performance by additional mechanisms, an overlaying threshold can be defined. An overlaying threshold can comprise one or more thresholds defined by multiple parameters. An overlaying threshold can result in one or more thresholds being an input into the generation of another threshold or thresholds. An overlaying threshold can be predetermined or dynamically generated such as at runtime. The overlaying threshold may come into effect when you the threshold is defined by multiple inputs. For example, as the number of sterilization cycles exceeds 300 (the marginal threshold) but not 500 (the ultimate threshold) the device runs the motor slower. Then as the current draw exceeds its 75% marginal threshold it multiples the slow down going even slower. 
       FIG.  19    illustrates a logic diagram of a system  4311  for evaluating sharpness of a cutting edge  182  ( FIG.  14   ) of a surgical instrument  10  ( FIGS.  1 - 4   ) according to various examples. In certain instances, the system  4311  can evaluate the sharpness of the cutting edge  182  by testing the ability of the cutting edge  182  to be advanced through a sharpness testing member  4302 . For example, the system  4311  can be configured to observe the time period the cutting edge  182  takes to fully transect and/or completely pass through at least a predetermined portion of a sharpness testing member  4302 . If the observed time period exceeds a predetermined threshold, the circuit  4310  may conclude that the sharpness of the cutting edge  182  has dropped below an acceptable level, for example. 
     In one aspect, the sharpness testing member  4302  can be employed to test the sharpness of the cutting edge  182  ( FIG.  14   ). In certain instances, the sharpness testing member  4302  can be attached to and/or integrated with the cartridge body  194  ( FIG.  14   ) of the surgical staple cartridge  304  ( FIGS.  1 ,  2 , and  15   ), for example. In certain instances, the sharpness testing member  4302  can be disposed in the proximal portion of the surgical staple cartridge  304 , for example. In certain instances, the sharpness testing member  4302  can be disposed onto a cartridge deck or cartridge body  194  of the surgical staple cartridge  304 , for example. 
     In certain instances, a load cell  4335  can be configured to monitor the force (Fx) applied to the cutting edge  182  ( FIG.  14   ) while the cutting edge  182  is engaged and/or in contact with the sharpness testing member  4302 , for example. The reader will appreciate that the force (Fx) applied by the sharpness testing member  4302  to the cutting edge  182  while the cutting edge  182  is engaged and/or in contact with the sharpness testing member  4302  may depend, at least in part, on the sharpness of the cutting edge  182 . In certain instances, a decrease in the sharpness of the cutting edge  182  can result in an increase in the force (Fx) required for the cutting edge  182  to cut or pass through the sharpness testing member  4302 . The load cell  4335  of the sharpness testing member  4302  may be employed to measure the force (Fx) applied to the cutting edge  182  while the cutting edge  182  travels a predefined distance (D) through the sharpness testing member  4302  may be employed to determine the sharpness of the cutting edge  182 . 
     In certain instances, the system  4311  may include a controller  4313  (“microcontroller”) which may include a processor  4315  (“microprocessor”) and one or more computer readable mediums or memory  4317  units (“memory”). In certain instances, the memory  4317  may store various program instructions, which when executed may cause the processor  4315  to perform a plurality of functions and/or calculations described herein. In certain instances, the memory  4317  may be coupled to the processor  4315 , for example. A power source  4319  can be configured to supply power to the controller  4313 , for example. In certain instances, the power source  4319  may comprise a battery (or “battery pack” or “power pack”), such as a Li ion battery, for example. In certain instances, the battery pack may be configured to be releasably mounted to the handle assembly  14 . A number of battery cells connected in series may be used as the power source  4319 . In certain instances, the power source  4319  may be replaceable and/or rechargeable, for example. 
     In certain instances, the controller  4313  can be operably coupled to the feedback system and/or the lockout mechanism  4123 , for example. 
     The system  4311  may comprise one or more position sensors. Example position sensors and positioning systems suitable for use with the present disclosure are described in U.S. Patent Application Publication No. 2014/0263538, entitled SENSOR ARRANGEMENTS FOR ABSOLUTE POSITIONING SYSTEM FOR SURGICAL INSTRUMENTS, which is herein incorporated by reference in its entirety. In certain instances, the system  4311  may include a first position sensor  4321  and a second position sensor  4323 . In certain instances, the first position sensor  4321  can be employed to detect a first position of the cutting edge  182  ( FIG.  14   ) at a proximal end of a sharpness testing member  4302 , for example; and the second position sensor  4323  can be employed to detect a second position of the cutting edge  182  at a distal end of a sharpness testing member  4302 , for example. 
     In certain instances, the first and second position sensors  4321 ,  4323  can be employed to provide first and second position signals, respectively, to the controller  4313 . It will be appreciated that the position signals may be analog signals or digital values based on the interface between the controller  4313  and the first and second position sensors  4321 ,  4323 . In one example, the interface between the controller  4313  and the first and second position sensors  4321 ,  4323  can be a standard serial peripheral interface (SPI), and the position signals can be digital values representing the first and second positions of the cutting edge  182 , as described above. 
     Further to the above, the processor  4315  may determine the time period between receiving the first position signal and receiving the second position signal. The determined time period may correspond to the time it takes the cutting edge  182  ( FIG.  14   ) to advance through a sharpness testing member  4302  from the first position at a proximal end of the sharpness testing member  4302 , for example, to a second position at a distal end of the sharpness testing member  4302 , for example. In at least one example, the controller  4313  may include a time element which can be activated by the processor  4315  upon receipt of the first position signal, and deactivated upon receipt of the second position signal. The time period between the activation and deactivation of the time element may correspond to the time it takes the cutting edge  182  to advance from the first position to the second position, for example. The time element may comprise a real time clock, a processor configured to implement a time function, or any other suitable timing circuit. 
     In various instances, the controller  4313  can compare the time period it takes the cutting edge  182  ( FIG.  14   ) to advance from the first position to the second position to a predefined threshold value to assess whether the sharpness of the cutting edge  182  has dropped below an acceptable level, for example. In certain instances, the controller  4313  may conclude that the sharpness of the cutting edge  182  has dropped below an acceptable level if the measured time period exceeds the predefined threshold value by 1%, 5%, 10%, 25%, 50%, 100% and/or more than 100%, for example. 
       FIG.  20    illustrates a logic diagram of a system  4340  for determining the forces applied against a cutting edge of a surgical instrument  10  ( FIGS.  1 - 4   ) by a sharpness testing member  4302  at various sharpness levels according to various aspects. Referring to  FIG.  20   , in various instances, an electric motor  4331  can drive the firing bar  172  ( FIG.  20   ) to advance the cutting edge  182  ( FIG.  14   ) during a firing stroke and/or to retract the cutting edge  182  during a return stroke, for example. A motor driver  4333  can control the electric motor  4331 ; and a controller such as, for example, the controller  4313  can be in signal communication with the motor driver  4333 . As the electric motor  4331  advances the cutting edge  182 , the controller  4313  can determine the current drawn by the electric motor  4331 , for example. In such instances, the force required to advance the cutting edge  182  can correspond to the current drawn by the electric motor  4331 , for example. Referring still to  FIG.  20   , the controller  4313  of the surgical instrument  10  can determine if the current drawn by the electric motor  4331  increases during advancement of the cutting edge  182  and, if so, can calculate the percentage increase of the current. 
     In certain instances, the current drawn by the electric motor  4331  may increase significantly while the cutting edge  182  ( FIG.  14   ) is in contact with the sharpness testing member  4302  due to the resistance of the sharpness testing member  4302  to the cutting edge  182 . For example, the current drawn by the electric motor  4331  may increase significantly as the cutting edge  182  engages, passes and/or cuts through the sharpness testing member  4302 . The reader will appreciate that the resistance of the sharpness testing member  4302  to the cutting edge  182  depends, in part, on the sharpness of the cutting edge  182 ; and as the sharpness of the cutting edge  182  decreases from repetitive use, the resistance of the sharpness testing member  4302  to the cutting edge  182  will increase. Accordingly, the value of the percentage increase of the current drawn by the electric motor  4331  while the cutting edge is in contact with the sharpness testing member  4302  can increase as the sharpness of the cutting edge  182  decreases from repetitive use, for example. 
     In certain instances, the determined value of the percentage increase of the current drawn by the electric motor  4331  can be the maximum detected percentage increase of the current drawn by the electric motor  4331 . In various instances, the controller  4313  can compare the determined value of the percentage increase of the current drawn by the electric motor  4331  to a predefined threshold value of the percentage increase of the current drawn by the electric motor  4331 . If the determined value exceeds the predefined threshold value, the controller  4313  may conclude that the sharpness of the cutting edge  182  has dropped below an acceptable level, for example. 
     In certain instances, as illustrated in  FIG.  20   , the processor  4315  can be in communication with the feedback system and/or the lockout mechanism for example. In certain instances, the processor  4315  can employ the feedback system to alert a user if the determined value of the percentage increase of the current drawn by the electric motor  4331  exceeds the predefined threshold value, for example. In certain instances, the processor  4315  may employ the lockout mechanism to prevent advancement of the cutting edge  182  ( FIG.  14   ) if the determined value of the percentage increase of the current drawn by the electric motor  4331  exceeds the predefined threshold value, for example. In certain instances, the system  4311  may include first and second position sensors  4321 ,  4323 . The surgical instrument  10  ( FIGS.  1 - 4   ) may include a load cell  4335 . 
     In various instances, the controller  4313  can utilize an algorithm to determine the change in current drawn by the electric motor  4331 . For example, a current sensor can detect the current drawn by the electric motor  4331  during the firing stroke. The current sensor can continually detect the current drawn by the electric motor and/or can intermittently detect the current draw by the electric motor. In various instances, the algorithm can compare the most recent current reading to the immediately proceeding current reading, for example. Additionally or alternatively, the algorithm can compare a sample reading within a time period X to a previous current reading. For example, the algorithm can compare the sample reading to a previous sample reading within a previous time period X, such as the immediately proceeding time period X, for example. In other instances, the algorithm can calculate the trending average of current drawn by the motor. The algorithm can calculate the average current draw during a time period X that includes the most recent current reading, for example, and can compare that average current draw to the average current draw during an immediately proceeding time period time X, for example. 
     In certain instances, the load cell  4335  ( FIGS.  19 ,  20   ) can be configured to monitor the force (Fx) applied to the cutting edge  182  ( FIG.  14   ) while the cutting edge  182  is engaged and/or in contact with the sharpness testing member  4302  ( FIGS.  19 ,  20   ), for example. The reader will appreciate that the force (Fx) applied by the sharpness testing member  4302  to the cutting edge  182  while the cutting edge  182  is engaged and/or in contact with the sharpness testing member  4302  may depend, at least in part, on the sharpness of the cutting edge  182 . In certain instances, a decrease in the sharpness of the cutting edge  182  can result in an increase in the force (Fx) required for the cutting edge  182  to cut or pass through the sharpness testing member  4302 . In certain instances, the controller  4313  ( FIGS.  19 ,  20   ) may compare a maximum value of the monitored force (Fx) applied to the cutting edge  182  ( FIG.  14   ) to one or more predefined threshold values. 
     In certain instances, the cutting edge  182  ( FIG.  14   ) may be sufficiently sharp for transecting a captured tissue comprising a first thickness but may not be sufficiently sharp for transecting a captured tissue comprising a second thickness greater than the first thickness, for example. In certain instances, a sharpness level of the cutting edge  182 , as defined by the force required for the cutting edge  182  to transect a captured tissue, may be adequate for transecting the captured tissue if the captured tissue comprises a tissue thickness that is in a particular range of tissue thicknesses, for example. In certain instances, the memory  4317  ( FIGS.  19 ,  20   ) can store one or more predefined ranges of tissue thicknesses of tissue captured by the end effector  300 ; and predefined threshold forces associated with the predefined ranges of tissue thicknesses. In certain instances, each predefined threshold force may represent a minimum sharpness level of the cutting edge  182  that is suitable for transecting a captured tissue comprising a tissue thickness (Tx) encompassed by the range of tissue thicknesses that is associated with the predefined threshold force. In certain instances, when the force (Fx) required for the cutting edge  182  to transect the captured tissue, comprising the tissue thickness (Tx), exceeds the predefined threshold force associated with the predefined range of tissue thicknesses that encompasses the tissue thickness (Tx), the cutting edge  182  may not be sufficiently sharp to transect the captured tissue, for example. 
     In various aspects, the present disclosure provides techniques for determining tissue compression and additional techniques to control the operation of the surgical instrument  10  (described in connection with  FIGS.  1 - 18   ) in response to the tissue compression. In one example, the cartridges may be configured to define variable compression algorithm which drives the surgical instrument  10  to close differently based on intended tissue type and thickness. In another example, the surgical instrument  10  learns from surgeon use and original tissue compression profile to adapt closure based on load experienced during firing. When the surgical instrument  10  experiences tissue compression loads that are dramatically different that those experienced for this cartridge type the instrument highlights this to the user. 
     Active adjustment of a motor control algorithm over time as the instrument become acclimated to the hospital&#39;s usage can improve the life expectancy of a rechargeable battery as well as adjust to tissue/procedure requirements of minimizing tissue flow, thus improving staple formation in the tissue seal. 
     Accordingly, the present disclosure relates to surgical instruments and, in various circumstances, to surgical stapling and cutting instruments and staple cartridges therefor that are designed to staple and cut tissue. For example, in various aspects the present disclosure provides an endosurgical instrument configured to sense the cartridge type or tissue gap to enable the handle to adjust the closure and firing algorithms to adjust for intended tissue properties. This adaptive algorithm adjustment can “learn” from the user&#39;s operations allowing the device to react and benefit two different systems. The first benefit provided by the disclosed adaptive algorithm includes tissue flow and staple formation. As the device learns the users&#39; basic habits and step timings, the device can adjust the closure speed and firing speed to provide a more consistent and reliable output. The second benefit provided by the disclosed adaptive algorithm is related to the battery pack. As the device learns how many firings and what conditions the instrument was used, the device can adjust motor current needs/speed in a predefined manner to prolong battery life. There is a substantially small likelihood that a device used in a hospital that performs predominantly bariatric procedures would be operated in a manner similar to a device used in a hospital that performs mostly colorectal or thoracic procedures. Thus, when the device is used to perform substantially similar procedure, over time, the device is configured to learn and adjust its operational algorithm to maintain within the “ideal” discharge and tissue flow envelopes. 
     Safe and effective surgery requires due knowledge of, and respect for, the tissue involved. Clinicians are mindful that adjustments made during surgery may be beneficial. These adjustments include mechanisms to detect and promote desirable staple formation. 
     Endosurgical instruments can generate, monitor and process a substantial amount of data during their use in connection with a surgical procedure. Such data can be obtained from the surgical instrument itself, including battery usage. Additionally, data can be obtained from the properties of the tissue with which the surgical instrument interacts, including properties such as tissue compression. Further, data can be obtained from the clinician&#39;s interaction with the surgical instrument itself. The repository of data so obtained can be processed and, where desired, the surgical instrument can be designed to adapt to circumstances so as to promote a safe and effective outcome to the current surgical procedure, as well as lay the foundation for more generalized productive use by multiple clinicians. Such adaptive adjustments—both during a surgical procedure, and wherein the instrument “learns” based on usage patterns drawn from multiple surgical procedures—can provide numerous mechanisms to enhance the overall patient-care environment. 
       FIG.  21    illustrates one aspect of a process for adapting operations of a surgical instrument. As depicted in  FIG.  21   , a module can be attached  5160  or otherwise loaded to the surgical instrument  10  ( FIGS.  1 - 4   ). The module can contain a program that is selected or uploaded  5162 . Controls can be activated  5164  such that they can be ready to operate the surgical instrument  10 . During or after usage of the surgical instrument  10 , control measures can be included to adapt  5166  a program. For example, this can include adjusting the data rate within the surgical instrument  10  or with respect to remote operation of the surgical instrument  10 . This can include adjusting speed, such as speed by which anvil  306  ( FIG.  1   ) and surgical staple cartridge  304  ( FIG.  1   ) engage in a closure motion. This can also include a pulse from an emitter and sensor or to apply a pulse of electrical current to tissue, and the timing of such pulse. This can include adjusting a program to adapt to acceleration, such as acceleration of the surgical instrument  10  if dropped, or transition from a sleep mode. A program can be adapted to handle an actual and/or expected load based on clamping force. 
     The surgical instrument  10  ( FIGS.  1 - 4   ) can be employed to complete an action  5168 , for example to carry out a stapling procedure. Data can be recorded  5170  in appropriate memory locations of the surgical instrument  10 . Sensor behavior  5172  can be assessed, such as to what extent a sensor accurately measured and/or measures a parameter. Anticipated data can be assessed  5174 , including but not limited to tissue properties, wait period and firing speed. Foregoing mechanisms disclosed herein can provide an input to adapt  5166  a program further. In addition, a tissue identification  5178  can be performed, based on historical, actual or expected tissue properties, and this can provide an input to further adapt  5166  a program. In addition, tissue identification  5178  properties can be updated. Moreover, measured sensor input  5176  during a procedure can be used as an additional input to further adapt  5166  a program; such sensor measurements can include those of the gap between anvil  306  and surgical staple cartridge  304 , obtaining a derivative measurement including a derivative of a function, current, or torque. 
     The end-effector  6006  may be used to compress, cut, or staple tissue. Referring now to  FIG.  23 A , an end-effector  6030  may be positioned by a physician to surround tissue  6032  prior to compression, cutting, or stapling. As shown in  FIG.  23 A , no compression may be applied to the tissue while preparing to use the end-effector. Referring now to  FIG.  23 B , by engaging the handle (e.g., handle  6002 ) of the endocutter, the physician may use the end-effector  6030  to compress the tissue  6032 . In one aspect, the tissue  6032  may be compressed to its maximum threshold, as shown in  FIG.  23 B . 
     Referring to  FIG.  23 A , various forces may be applied to the tissue  6032  by the end-effector  6030 . For example, vertical forces F 1  and F 2  may be applied by the anvil  6034  and the channel frame  6036  of the end-effector  6030  as tissue  6032  is compressed between the two. Referring now to  FIG.  23 B , various diagonal and/or lateral forces also may be applied to the tissue  6032  when compressed by the end-effector  6030 . For example, force F 3  may be applied. For the purposes of operating a medical device such as endocutter  6000 , it may be desirable to sense or calculate the various forms of compression being applied to the tissue by the end-effector. For example, knowledge of vertical or lateral compression may allow the end-effector to more precisely or accurately apply a staple operation or may inform the operator of the endocutter such that the endocutter can be used more properly or safely. 
     The compression through tissue  6032  may be determined from an impedance of tissue  6032 . At various levels of compression, the impedance Z of tissue  6032  may increase or decrease. By applying a voltage V and a current I to the tissue  6032 , the impedance Z of the tissue  6032  may be determined at various levels of compression. For example, impedance Z may be calculated by dividing the applied voltage V by the current I. 
     Referring now to  FIG.  24   , in one aspect, an RF electrode  6038  may be positioned on the end-effector  6030  (e.g., on a staple cartridge, knife, or channel frame of the end-effector  6030 ). Further, an electrical contact  6040  may be positioned on the anvil  6034  of the end-effector  6030 . In one aspect, the electrical contact may be positioned on the channel frame of the end-effector. As the tissue  6032  is compressed between the anvil  6034  and, for example, the channel frame  6036  of the end-effector  6030 , an impedance Z of the tissue  6032  changes. The vertical tissue compression  6042  caused by the end-effector  6030  may be measured as a function of the impedance Z of the tissue  6032 . 
     Referring now to  FIG.  25   , in one aspect, an electrical contact  6044  may be positioned on an opposite end of the anvil  6034  of the end-effector  6030  as the RF electrode  6038  is positioned. As the tissue  6032  is compressed between the anvil  6034  and, for example, the channel frame  6036  of the end-effector  6030 , an impedance Z of the tissue  6032  changes. The lateral tissue compression  6046  caused by the end-effector  6030  may be measured as a function of the impedance Z of the tissue  6032 . 
     Referring now to  FIG.  26   , in one aspect, electrical contact  6050  may be positioned on the anvil  6034  and electrical contact  6052  may be positioned on an opposite end of the end-effector  6030  at channel frame  6036 . RF electrode  6048  may be positioned laterally to the central to the end-effector  6030 . As the tissue  6032  is compressed between the anvil  6034  and, for example, the channel frame  6036  of the end-effector  6030 , an impedance Z of the tissue  6032  changes. The lateral compression or angular compressions  6054  and  6056  on either side of the RF electrode  6048  may be caused by the end-effector  6030  and may be measured as a function of different impedances Z of the tissue  6032 , based on the relative positioning of the RF electrode  6048  and electrical contacts  6050  and  6052 . 
     In accordance with one or more of the techniques and features described in the present disclosure, and as discussed above, an RF electrode may be used as an RF sensor. Referring now to  FIG.  27   , in one aspect, an RF sensor  6062  may be positioned on a staple cartridge  6060  inserted into a channel frame  6066  an end-effector. The RF electrode may run from a power line  6064  which may be powered by a power source in a handle (e.g., handle  6002 ) of an endocutter. 
     Referring now to  FIG.  28   , in one aspect, RF electrodes  6074  and  6076  may be positioned on a staple cartridge  6072  inserted into a channel frame  6078  of end-effector  6070 . As shown, RF electrode  6074  may be placed in a proximal position of the end-effector relative to an endocutter handle. Further, RF electrode  6076  may be placed in a distal position of the end-effector relative to the endocutter handle RF electrodes  6074  and  6076  may be utilized to measure vertical, lateral, proximal, or distal compression at different points in a tissue based on the position of one or more electrical contacts on the end-effector. 
     Referring now to  FIG.  29   , in one aspect, RF electrodes  6084 - 6116  may be positioned on staple cartridge  6082  inserted into the channel frame  6080  (or other component of an end-effector) based on various points for which compression information is desired. Referring now to  FIG.  30   , in one aspect, RF electrodes  6122 - 6140  may be positioned on staple cartridge  6120  at discrete points for which compression information is desired. Referring now to  FIG.  31   , RF electrodes  6152 - 6172  may be positioned at different points in multiple zones of a staple cartridge based on how accurate or precise the compression measurements should be. For example, RF electrodes  6152 - 6156  may be positioned in zone  6158  of staple cartridge  6150  depending on how accurate or precise the compression measurements in zone  6158  should be. Further, RF electrodes  6160 - 6164  may be positioned in zone  6166  of staple cartridge  6150  depending on how accurate or precise the compression measurements in zone  6166  should be. Additionally, RF electrodes  6168 - 6172  may be positioned in zone  6174  of staple cartridge  6150  depending on how accurate or precise the compression measurements in zone  6174  should be. 
     The RF electrodes discussed herein may be wired through a staple cartridge inserted in the channel frame. Referring now to  FIG.  32   , in one aspect, an RF electrode may have a stamped “mushroom head”  6180  of about 1.0 mm in diameter. While the RF electrode may have the stamped “mushroom head” of about 1.0 mm in diameter, this is intended to be a non-limiting example and the RF electrode may be differently shaped and sized depending on each particular application or design. The RF electrode may be connected to, fastened to, or may form, a conductive wire  6182 . The conductive wire  6182  may be about 0.5 mm in diameter, or may have a larger or smaller diameter based on a particular application or design. Further, the conductive wire may have an insulative coating  6184 . In one example, the RF electrode may protrude through a staple cartridge, channel frame, knife, or other component of an end-effector. 
     Referring now to  FIG.  33   , the RF electrodes may be wired through a single wall or through multiple walls of a staple cartridge or channel frame of an end-effector. For example, RF electrodes  6190 - 6194  may be wired through wall  6196  of the staple cartridge or channel frame of an end-effector. One or more of wires  6198  may be connected to, fastened to, or be part of, RF electrodes  6190 - 6194  and may run through wall  6196  from a power source in, e.g., a handle of an endocutter. 
     Referring now to  FIG.  34   , the power source may be in communication with the RF electrodes or may provide power to the RF electrodes through a wire or cable. The wire or cable may join each individual wire and lead to the power source. For example, RF electrodes  6204 - 6212  may receive power from a power source through wire or cable  6202 , which may run through staple cartridge  6200  or a channel frame of an end-effector. In one example, each of RF electrodes  6204 - 6212  may have its own wire that runs to or through wire or cable  6202 . The staple cartridge  6200  or channel frame also may include a controller  6214 , such as the primary processor  2006  shown in connection with  FIGS.  16 A and  16 B , or the main controller  3017  shown in connection with  FIGS.  17 A,  17 B, and  18   , for example. It will be appreciated that the controller  6214  should be suitably sized to fit in the staple cartridge  6200  or channel frame form factor. Also, the controller 
     In various aspects, the tissue compression sensor system described herein for use with medical devices may include a frequency generator. The frequency generator may be located on a circuit board of the medical device, such as an endocutter. For example the frequency generator may be located on a circuit board in a shaft or handle of the endocutter. Referring now to  FIG.  35   , an example circuit diagram  6220  in accordance with one example of the present disclosure is shown. As shown, frequency generator  6222  may receive power or current from a power source  6221  and may supply one or more RF signals to one or more RF electrodes  6224 . As discussed above, the one or more RF electrodes may be positioned at various locations or components on an end-effector or endocutter, such as a staple cartridge or channel frame. One or more electrical contacts, such as electrical contacts  6226  or  6228  may be positioned on a channel frame or an anvil of an end-effector. Further, one or more filters, such as filters  6230  or  6232  may be communicatively coupled to the electrical contacts  6226  or  6228  as shown in  FIG.  35   . The filters  6230  and  6232  may filter one or more RF signals supplied by the frequency generator  6222  before joining a single return path  6234 . A voltage V and a current I associated with the one or more RF signals may be used to calculate an impedance Z associated with a tissue that may be compressed and/or communicatively coupled between the one or more RF electrodes  6224  and the electrical contacts  6226  or  6228 . 
     Referring now to  FIG.  36   , various components of the tissue compression sensor system described herein may be located in a handle  6236  of an endocutter. For example, as shown in circuit diagram  6220   a , frequency generator  6222  may be located in the handle  6236  and receives power from power source  6221 . Also, current I 1  and current I 2  may be measured on a return path corresponding to electrical contacts  6228  and  6226 . Using a voltage V applied between the supply and return paths, impedances Z 1  and Z 2  may be calculated. Z 1  may correspond to an impedance of a tissue compressed and/or communicatively coupled between one or more of RF electrodes  6224  and electrical contact  6228 . Further, Z 2  may correspond to an impedance of a tissue compressed and/or communicatively coupled between one or more of RF electrodes  6224  and electrical contact  6226 . Applying the formulas Z 1 =V/I 1  and Z 2 =V/I 2 , impedances Z 1  and Z 2  corresponding to different compression levels of a tissue compressed by an end-effector may be calculated. 
     Referring now to  FIG.  37   , one or more aspects of the present disclosure are described in circuit diagram  6250 . In an implementation, a power source at a handle  6252  of an endocutter may provide power to a frequency generator  6254 . The frequency generator  6254  may generate one or more RF signals. The one or more RF signals may be multiplexed or overlaid at a multiplexer  6256 , which may be in a shaft  6258  of the endocutter. In this way, two or more RF signals may be overlaid (or, e.g., nested or modulated together) and transmitted to the end-effector. The one or more RF signals may energize one or more RF electrodes  6260  at an end-effector  6262  (e.g., positioned in a staple cartridge) of the endocutter. A tissue (not shown) may be compressed and/or communicatively coupled between the one or more of RF electrodes  6260  and one or more electrical contacts. For example, the tissue may be compressed and/or communicatively coupled between the one or more RF electrodes  6260  and the electrical contact  6264  positioned in a channel frame of the end-effector  6262  or the electrical contact  6266  positioned in an anvil of the end-effector  6262 . A filter  6268  may be communicatively coupled to the electrical contact  6264  and a filter  6270  may be communicatively coupled to the electrical contact  6266 . 
     A voltage V and a current I associated with the one or more RF signals may be used to calculate an impedance Z associated with a tissue that may be compressed between the staple cartridge (and communicatively coupled to one or more RF electrodes  6260 ) and the channel frame or anvil (and communicatively coupled to one or more of electrical contacts  6264  or  6266 ). 
     In one aspect, various components of the tissue compression sensor system described herein may be located in a shaft  6258  of the endocutter. For example, as shown in circuit diagram  6250  (and in addition to the frequency generator  6254 ), an impedance calculator  6272 , a controller  6274 , a non-volatile memory  6276 , and a communication channel  6278  may be located in the shaft  6258 . In one example, the frequency generator  6254 , impedance calculator  6272 , controller  6274 , non-volatile memory  6276 , and communication channel  6278  may be positioned on a circuit board in the shaft  6258 . 
     The two or more RF signals may be returned on a common path via the electrical contacts. Further, the two or more RF signals may be filtered prior to the joining of the RF signals on the common path to differentiate separate tissue impedances represented by the two or more RF signals. Current I 1  and current I 2  may be measured on a return path corresponding to electrical contacts  6264  and  6266 . Using a voltage V applied between the supply and return paths, impedances Z 1  and Z 2  may be calculated. Z 1  may correspond to an impedance of a tissue compressed and/or communicatively coupled between one or more of RF electrodes  6260  and electrical contact  6264 . Further, Z 2  may correspond to an impedance of the tissue compressed and/or communicatively coupled between one or more of RF electrodes  6260  and electrical contact  6266 . Applying the formulas Z 1 =V/I 1  and Z 2 =V/I 2 , impedances Z 1  and Z 2  corresponding to different compressions of a tissue compressed by an end-effector  6262  may be calculated. In example, the impedances Z 1  and Z 2  may be calculated by the impedance calculator  6272 . The impedances Z 1  and Z 2  may be used to calculate various compression levels of the tissue. 
     In one aspect, filters  6268  and  6270  may be High Q filters such that the filter range may be narrow (e.g., Q=10). Q may be defined by the Center frequency (Wo)/Bandwidth (BW) where Q=Wo/BW. In one example, Frequency 1 may be 150 kHz and Frequency 2 may be 300 kHz. A viable impedance measurement range may be 100 kHz-20 MHz. In various examples, other sophisticated techniques, such as correlation, quadrature detection, etc., may be used to separate the RF signals. 
     Using one or more of the techniques and features described herein, a single energized electrode on a staple cartridge or an isolated knife of an end-effector may be used to make multiple tissue compression measurements simultaneously. If two or more RF signals are overlaid or multiplexed (or nested or modulated), they may be transmitted down a single power side of the end-effector and may return on either the channel frame or the anvil of the end-effector. If a filter were built into the anvil and channel contacts before they join a common return path, the tissue impedance represented by both paths could be differentiated. This may provide a measure of vertical tissue vs lateral tissue compression. This approach also may provide proximal and distal tissue compression depending on placement of the filters and location of the metallic return paths. A frequency generator and signal processor may be located on one or more chips on a circuit board or a sub board (which may already exist in an endocutter). 
     In various aspects, the present disclosure provides techniques for monitoring the speed and precision incrementing of the drive motor in the surgical instrument  10  (described in connection with  FIGS.  1 - 18   ). In one example, a magnet can be placed on a planet frame of one of the stages of gear reduction with an inductance sensor on the gear housing. In another example, placing the magnet and magnetic field sensor on the last stage would provide the most precise incremental movement monitoring. 
     Conventional motor control systems employ encoders to detect the location and speed of the motor in hand held battery powered endosurgical instruments such as powered endocutter/stapler devices. Precision operation of endocutter/stapler devices relies in part on the ability to verify the motor operation under load. Simple sensor implementations may be employed to achieve verify the motor operation under load. 
     Accordingly, the present disclosure includes a magnetic body on one of the planetary carriers of a gear reduction system or employ brushless motor technology. Both approaches involve the placement of an inductance sensor on the outside housing of the motor or planetary gear system. In the case of a brushless motor there are electromagnetic field coils (windings, inductors, etc.) arrayed radially around the center magnetic shaft of the motor. The coils are sequentially activated and deactivated to drive the central motor shaft. One or more inductance sensors can be placed outside of the motor and adjacent to at least some of the coils to sense the activation/deactivation cycles of the motor windings to determine the number times the shaft has been rotated. Alternatively, a permanent magnet can be placed on one of the planetary carriers and the inductance sensor can be placed adjacent to the radial path of the planetary carrier to measure the number of times that stage of the gear train is rotated. This implementation can be applied to any rotational components in the system with increasingly more resolution possible in regions with a relatively large number of rotations during function, or as the rotational components become closer (in terms of number of connections) to the end effector depending on the design. The gear train sensing method may be preferred since it actually measures rotation of one of the stages whereas the motor sensing method senses the number of times the motor has been commanded to energize, rather than the actual shaft rotation. For example, if the motor is stalled under high load, the motor sensing method would not be able to detect the lack of rotation because it senses only the energizing cycles not shaft rotation. Nevertheless, both techniques can be employed in a cost effective manner to sense motor rotation. 
     During stapling, for example, tissue is firmly clamped between opposing jaws before a staple is driven into the clamped tissue. Tissue compression during clamping can cause fluid to be displaced from the compressed tissue, and the rate or amount of displacement varies depending on tissue type, tissue thickness, the surgical operation (e.g., clamping pressure and clamping time). In various instances, fluid displacement between the opposing jaws of an end effector may contribute to malformation (e.g., bending) of staples between the opposing jaws. Accordingly, in various instances, it may be desirable to control the firing stroke, e.g., to control the firing speed, in relationship to the detected fluid flow, or lack thereof, intermediate opposing jaws of a surgical end effector. 
     Accordingly, also provided herein are methods, devices, and systems for monitoring speed and incremental movement of a surgical instrument drive train, which in turn provides information about the operational velocity of the device (e.g., jaw closure, stapling). In accordance with the present examples, the surgical instrument  10  ( FIGS.  1 - 4   ) does not include a motor encoder. Rather, the surgical instrument  10  may be equipped with a motor comprising a speed sensor assembly for a power train of the motor, in accordance with an illustrative example. The speed sensor assembly can include a motor having an output shaft that is coupled directly or indirectly to a drive shaft. In some examples, the output shaft is connected to a gear reduction assembly, such as a planetary gear train comprising a sensor that detects the rotational speed of any suitable component of the system. For example, the sensor may be a proximity sensor, such as an induction sensor, which detects movement of one or more detectable elements affixed to any rotating part of the gear reduction assembly. The detectable element is affixed to the last stage annular gear and the sensor is positioned adjacent the radial path of the detectable element so as to detect movement of the detectable element. Rotating components may vary depending on design—and the sensor(s) can be affixed to any rotating component of the gear reduction assembly. For example, in another example, a detectable element is associated with the carrier gear of the final stage or even the drive gear. In some examples, a detectable element is located outside of the gear reduction assembly, such as on the driveshaft between gear reduction assembly and the end effector. In some example, a detectable element is located on a rotating component in the final gear reduction at the end effector. 
     Various functions may be implemented utilizing the circuitry previously described, For example, the motor may be controlled with a motor controller similar those described in connection with  FIGS.  16 A,  16 B,  17 A,  17 B , and  18 , where the encoder is replaced with the monitoring speed control and precision incrementing of motor systems for powered surgical instruments described herein. 
     In one aspect, the present disclosure provides a surgical instrument  10  (described in connection with  FIGS.  1 - 18   ) configured with various sensing systems. Accordingly, for conciseness and clarity the details of operation and construction will not be repeated here. In one aspect, the sensing system includes a viscoelasticity/rate of change sensing system to monitor knife acceleration, rate of change of impedance, and rate of change of tissue contact. In one example, the rate of change of knife acceleration can be used as a measure of for tissue type. In another example, the rate of change of impedance can be measures with a pulse sensor ad can be employed as a measure for compressibility. Finally, the rate of change of tissue contact can be measured with a sensor based on knife firing rate to measure tissue flow. 
     The rate of change of a sensed parameter or stated otherwise, how much time is necessary for a tissue parameter to reach an asymptotic steady state value, is a separate measurement in itself and may be more valuable than the sensed parameter it was derived from. To enhance measurement of tissue parameters such as waiting a predetermined amount of time before making a measurement, the present disclosure provides a novel technique for employing the derivate of the measure such as the rate of change of the tissue parameter. 
     The derivative technique or rate of change measure becomes most useful with the understanding that there is no single measurement that can be employed alone to dramatically improve staple formation. It is the combination of multiple measurements that make the measurements valid. In the case of tissue gap it is helpful to know how much of the jaw is covered with tissue to make the gap measure relevant. Rate of change measures of impedance may be combined with strain measurements in the anvil to relate force and compression applied to the tissue grasped between the jaw members of the end effector such as the anvil and the staple cartridge. The rate of change measure can be employed by the endosurgical device to determine the tissue type and not merely the tissue compression. Although stomach and lung tissue sometimes have similar thicknesses, and even similar compressive properties when the lung tissue is calcified, an instrument may be able to distinguish these tissue types by employing a combination of measurements such as gap, compression, force applied, tissue contact area, and rate of change of compression or rate of change of gap. If any of these measurements were used alone, the endosurgical it may be difficult for the endosurgical device to distinguish one tissue type form another. Rate of change of compression also may be helpful to enable the device to determine if the tissue is “normal” or if some abnormality exists. Measuring not only how much time has passed but the variation of the sensor signals and determining the derivative of the signal would provide another measurement to enable the endosurgical device to measure the signal. Rate of change information also may be employed in determining when a steady state has been achieved to signal the next step in a process. For example, after clamping the tissue between the jaw members of the end effector such as the anvil and the staple cartridge, when tissue compression reaches a steady state (e.g., about 15 seconds), an indicator or trigger to start firing the device can be enabled. 
     Also provided herein are methods, devices, and systems for time dependent evaluation of sensor data to determine stability, creep, and viscoelastic characteristics of tissue during surgical instrument operation. A surgical instrument  10 , such as the stapler illustrated in  FIG.  1   , can include a variety of sensors for measuring operational parameters, such as jaw gap size or distance, firing current, tissue compression, the amount of the jaw that is covered by tissue, anvil strain, and trigger force, to name a few. These sensed measurements are important for automatic control of the surgical instrument and for providing feedback to the clinician. 
     The examples shown in connection with  FIGS.  22 A- 37    may be employed to measure the various derived parameters such as gap distance versus time, tissue compression versus time, and anvil strain versus time. Motor current may be monitored employing the current sensor  2312  in series with the battery  2308  as described herein, the current sensor  2412  in series with the battery  2408  or the current sensor  3027  in  FIG.  18   . 
       FIG.  38    illustrates a motor-driven surgical instrument  8010  for cutting and fastening that may or may not be reused. The surgical instrument  8010  is similarly constructed and equipped as the surgical instrument  10  for cutting and fastening described in connection with  FIGS.  1 - 18   . In the example illustrated in  FIG.  38   , the surgical instrument  8010  includes a housing  8012  that comprises a handle assembly  8014  that is configured to be grasped, manipulated and actuated by the clinician. The housing  8012  is configured for operable attachment to an interchangeable shaft assembly  8200  that has an end effector  8300  operably coupled thereto that is configured to perform one or more surgical tasks or procedures. Since the surgical instrument  8010  is similarly constructed and equipped as the surgical instrument  10  for cutting and fastening described in connection with  FIGS.  1 - 18   , for conciseness and clarity the details of operation and construction will not be repeated here. 
     The housing  8012  depicted in  FIG.  38    is shown in connection with an interchangeable shaft assembly  8200  that includes an end effector  8300  that comprises a surgical cutting and fastening device that is configured to operably support a surgical staple cartridge  8304  therein. The housing  8012  may be configured for use in connection with interchangeable shaft assemblies that include end effectors that are adapted to support different sizes and types of staple cartridges, have different shaft lengths, sizes, and types, etc. In addition, the housing  8012  also may be effectively employed with a variety of other interchangeable shaft assemblies including those assemblies that are configured to apply other motions and forms of energy such as, for example, radio frequency (RF) energy, ultrasonic energy and/or motion to end effector arrangements adapted for use in connection with various surgical applications and procedures. Furthermore, the end effectors, shaft assemblies, handles, surgical instruments, and/or surgical instrument systems can utilize any suitable fastener, or fasteners, to fasten tissue. For instance, a fastener cartridge comprising a plurality of fasteners removably stored therein can be removably inserted into and/or attached to the end effector of a shaft assembly. 
     Turning now to  FIG.  38   , the surgical instrument  8010  is depicted that may or may not be reused. The surgical instrument  8010  is similarly constructed and equipped as the surgical instrument  10  for cutting and fastening described herein. In the example illustrated in  FIG.  38   , the surgical instrument  8010  includes a housing  8012  that comprises a handle assembly  8014  that is configured to be grasped, manipulated and actuated by the clinician. The housing  8012  is configured for operable attachment to an interchangeable shaft assembly  8200  that has an end effector  8300  operably coupled thereto that is configured to perform one or more surgical tasks or procedures. Since the surgical instrument  8010  is similarly constructed and equipped as the surgical instrument  10  for cutting and fastening described herein in connection with  FIGS.  1 - 18   , for conciseness and clarity the details of operation and construction will not be repeated here. 
     The housing  8012  depicted in  FIG.  38    is shown in connection with an interchangeable shaft assembly  8200  that includes an end effector  8300  that comprises a surgical cutting and fastening device that is configured to operably support a surgical staple cartridge  8304  therein. The housing  8012  may be configured for use in connection with interchangeable shaft assemblies that include end effectors that are adapted to support different sizes and types of staple cartridges, have different shaft lengths, sizes, and types, etc. In addition, the housing  8012  also may be effectively employed with a variety of other interchangeable shaft assemblies including those assemblies that are configured to apply other motions and forms of energy such as, for example, radio frequency (RF) energy, ultrasonic energy and/or motion to end effector arrangements adapted for use in connection with various surgical applications and procedures. Furthermore, the end effectors, shaft assemblies, handles, surgical instruments, and/or surgical instrument systems can utilize any suitable fastener, or fasteners, to fasten tissue. For instance, a fastener cartridge comprising a plurality of fasteners removably stored therein can be removably inserted into and/or attached to the end effector of a shaft assembly. 
       FIG.  38    illustrates the surgical instrument  8010  with an interchangeable shaft assembly  8200  operably coupled thereto. In the illustrated arrangement, the handle housing forms a pistol grip portion  8019  that can be gripped and manipulated by the clinician. The handle assembly  8014  operably supports a plurality of drive systems therein that are configured to generate and apply various control motions to corresponding portions of the interchangeable shaft assembly that is operably attached thereto. Trigger  8032  is operably associated with the pistol grip for controlling various of these control motions. 
     With continued reference to  FIG.  38   , the interchangeable shaft assembly  8200  includes an end effector  8300  that comprises an elongated channel  8302  that is configured to operably support a surgical staple cartridge  8304  therein. The end effector  8300  may further include an anvil  8306  that is pivotally supported relative to the elongated channel  8302 . 
     The inventors have discovered that derived parameters can be even more useful for controlling a surgical instrument, such as the instrument illustrated in  FIG.  38   , than the sensed parameter(s) upon which the derived parameter is based. Non-limiting examples of derived parameters include the rate of change of a sensed parameter (e.g., jaw gap distance) and how much time elapses before a tissue parameter reaches an asymptotic steady state value (e.g., 15 seconds). Derived parameters, such as rate of change, are particularly useful because they dramatically improve measurement accuracy and also provide information not otherwise evident directly from sensed parameters. For example, impedance (i.e., tissue compression) rate of change can be combined with strain in the anvil to relate compression and force, which enables the controller to determine the tissue type and not merely the amount of tissue compression. This example is illustrative only, and any derived parameters can be combined with one or more sensed parameters to provide more accurate information about tissue types (e.g., stomach vs. lung), tissue health (calcified vs. normal), and operational status of the surgical device (e.g., clamping complete). Different tissues have unique viscoelastic properties and unique rates of change, making these and other parameters discussed herein useful indicia for monitoring and automatically adjusting a surgical procedure. 
     Specifically, referring to  FIGS.  38  and  39   , the gap  8040  is the distance between the anvil  8306  and the elongated channel  8302  of the end effector  8300 . In the open jaw position, at time zero, the gap  8040  between the anvil  8306  and the elongated member is at its maximum distance. The width of the gap  8040  decreases as the anvil  8306  closes, such as during tissue clamping. The gap distance rate of change can vary because tissue has non-uniform resiliency. For example, certain tissue types may initially show rapid compression, resulting in a faster rate of change. However, as tissue is continually compressed, the viscoelastic properties of the tissue can cause the rate of change to decrease until the tissue cannot be compressed further, at which point the gap distance will remain substantially constant. The gap decreases over time as the tissue is squeezed between the anvil  8306  and the surgical staple cartridge  8304  of the end effector  8300 . The one or more sensors described in connection with  FIGS.  22 A- 37    and  FIG.  40    may be adapted and configured to measure the gap distance “d” between the anvil  8306  and the surgical staple cartridge  8304  over time t and the rate of change of the gap distance “d” over time t is the Slope of the curve, where Slope=Δd/Δt. In addition, the rate of change of firing current is can be used as an indicator that the tissue is transitioning from one state to another state. Accordingly, firing current and, in particular, the rate of change of firing current can be used to monitor device operation. The firing current decreases over time as the knife cuts through the tissue. The rate of change of firing current can vary if the tissue being cut provides more or less resistance due to tissue properties or sharpness of the knife  8305  ( FIG.  39   ). For example, the motor current may be monitored employing the current sensor  2312  in series with the battery  2308  as described herein, the current sensor  2412  in series with the battery  2408  shown herein, or the current sensor  3027  shown in  FIG.  18   . The current sensors  2312 ,  2314 ,  3027  may be adapted and configured to measure the motor firing current “i” over time t and the rate of change of the firing current “i” over time t is the Slope of the curve, where Slope=Δi/Δt. The sensors described in connection with  FIGS.  22 A- 37  and  40    may be adapted and configured to measure tissue compression/impedance. The sensors may be adapted and configured to measure tissue impedance “Z” over time t and the rate of change of the tissue impedance “Z” over time t is the Slope, where 
     Slope=ΔZ/Δt. The rate of change of anvil  8306  strain can be measured by a pressure sensor or strain gauge positioned on either or both the anvil  8306  and the surgical staple cartridge  8304  ( FIGS.  38 ,  39   ) to measure the pressure or strain applied to the tissue grasped between the anvil  8306  and the surgical staple cartridge  8304 . Thus, at time zero, trigger  8020  ( FIG.  38   ) pressure may be at its lowest and trigger pressure may increase until completion of an operation (e.g., clamping, cutting, or stapling). The rate of change trigger force can be measured by a pressure sensor or strain gauge positioned on the trigger  8032  of the pistol grip portion  8019  of the handle of the surgical instrument  8010  ( FIG.  38   ) to measure the force required to drive the knife  8305  ( FIG.  39   ) through the tissue grasped between the anvil  8306  and the surgical staple cartridge  8304 . 
     Turning briefly to  FIG.  40   , the end effector  9012  is one aspect of the end effector  8300  ( FIG.  38   ) that may be adapted to operate with surgical instrument  8010  ( FIG.  38   ) to measure the various derived parameters such as gap distance versus time, tissue compression versus time, and anvil strain versus time. Accordingly, the end effector  9012  shown in  FIG.  40    may include one or more sensors configured to measure one or more parameters or characteristics associated with the end effector  9012  and/or a tissue section captured by the end effector  9012 . In the example illustrated in  FIG.  40   , the end effector  9012  comprises a first sensor  9020  and a second sensor  9026 . In various examples, the first sensor  9020  and/or the second sensor  9026  may comprise, for example, a magnetic sensor such as, for example, a magnetic field sensor, a strain gauge, a pressure sensor, a force sensor, an inductive sensor such as, for example, an eddy current sensor, a resistive sensor, a capacitive sensor, an optical sensor, and/or any other suitable sensor for measuring one or more parameters of the end effector  9012 . 
     In certain instances, the first sensor  9020  and/or the second sensor  9026  may comprise, for example, a magnetic field sensor embedded in an anvil  9014  and configured to detect a magnetic field generated by a magnet  9024  embedded in a jaw member  9016  and/or the staple cartridge  9018 . The anvil  9014  is pivotally rotatable between open and closed positions. The strength of the detected magnetic field may correspond to, for example, the thickness and/or fullness of a bite of tissue located between the anvil  9014  and the jaw member  9016 . In certain instances, the first sensor  9020  and/or the second sensor  9026  may comprise a strain gauge, such as, for example, a micro-strain gauge, configured to measure the magnitude of the strain in the anvil  9014  during a clamped condition. The strain gauge provides an electrical signal whose amplitude varies with the magnitude of the strain. 
     In some aspects, one or more sensors of the end effector  9012  such as, for example, the first sensor  9020  and/or the second sensor  9026  may comprise a pressure sensor configured to detect a pressure generated by the presence of compressed tissue between the anvil  9014  and the jaw member  9016 . In some examples, one or more sensors of the end effector  9012  such as, for example, the first sensor  9020  and/or the second sensor  9026  are configured to detect the impedance of a tissue section located between the anvil  9014  and the jaw member  9016 . The detected impedance may be indicative of the thickness and/or fullness of tissue located between the anvil  9014  and the jaw member  9016 . 
     In one aspect, one or more of the sensors of the end effector  9012  such as, for example, the first sensor  9020  is configured to measure the gap  9022  between the anvil  9014  and the jaw member  9016 . In certain instances, the gap  9022  can be representative of the thickness and/or compressibility of a tissue section clamped between the anvil  9014  and the jaw member  9016 . In at least one example, the gap  9022  can be equal, or substantially equal, to the thickness of the tissue section clamped between the anvil  9014  and the jaw member  9016 . In one example, one or more of the sensors of the end effector  9012  such as, for example, the first sensor  9020  is configured to measure one or more forces exerted on the anvil  9014  by the jaw member  9016  and/or tissue clamped between the anvil  9014  and the jaw member  9016 . The forces exerted on the anvil  9014  can be representative of the tissue compression experienced by the tissue section captured between the anvil  9014  and the jaw member  9016 . In one aspect, the gap  9022  between the anvil  9014  and the jaw member  9016  can be measured by positioning a magnetic field sensor on the anvil  9014  and positioning a magnet on the jaw member  9016  such that the gap  9022  is proportional to the signal detected by the magnetic field sensor and the signal is proportional to the distance between the magnet and the magnetic field sensor. It will be appreciated that the location of the magnetic field sensor and the magnet may be swapped such that the magnetic field sensor is positioned on the jaw member  9016  and the magnet is placed on the anvil  9014 . 
     One or more of the sensors such as, for example, the first sensor  9020  and/or the second sensor  9026  may be measured in real-time during a clamping operation. Real-time measurement allows time based information to be analyzed, for example, by a processor, and used to select one or more algorithms and/or look-up tables for the purpose of assessing, in real-time, a manual input of an operator of the surgical instrument  9010 . Furthermore, real-time feedback can be provided to the operator to assist the operator in calibrating the manual input to yield a desired output. 
       FIG.  41    is a logic diagram illustrating one aspect of a real-time feedback system  9060  for assessing, in real-time, a manual input  9064  of an operator of the surgical instrument  9010  and providing to the operator real-time feedback as to the adequacy of the manual input  9064 . With reference to  FIGS.  40  and  41   , in the example illustrated in  FIG.  41   , the real-time feedback system  9060  is comprised of a circuit. The circuit includes a controller  9061  comprising a processor  9062 . A sensor such as, for example, the first sensor  9020  is employed by the processor  9062  to measure a parameter of the end effector  9012 . In addition, the processor  9062  can be configured to determine or receive a value representative of a manual input  9064  of an operator of the surgical instrument  9010 . The manual input  9064  can be continuously assessed by the processor  9062  for as long as the manual input  9064  is being provided by the operator. The processor  9062  can be configured to monitor a value representative of the manual input  9064 . Furthermore, the processor  9062  is configured to assign, select, or determine a position, rank, and/or status for the determined value with respect to a desired zone or range. The measurement of the parameter of the end effector  9012  and the determined value can be employed by the processor  9062  to select or determine the position, rank, and/or status associated with the determined value, as described in greater detail below. A change in the manual input  9064  yields a change in the determined value which, in turn, yields a change in the position, rank, and/or status assigned to the determined value with respect to the desired zone or range. 
     As illustrated in  FIG.  41   , the real-time feedback system  9060  may further include a feedback indicator  9066  which can be adjusted between a plurality of positions, ranks, and/or statuses inside and outside a desired zone or range. In one example, the processor  9062  may select a first position (P 1 ), rank, and/or status that characterizes the manual input  9064  based on a measurement (M 1 ) of a parameter of the end effector  9012  and a first determined value (V 1 ) representing a first manual input (I 1 ). In certain instances, the first position (P 1 ), rank, and/or status may fall outside the desired zone or range. In such instances, the operator may change the manual input  9064  from the first manual input (I 1 ) to a second manual input (I 2 ) by increasing or decreasing the manual input  9064 , for example. In response, the processor  9062  may adjust the feedback indicator  9066  from the first position (P 1 ), rank, and/or status to a second position (P 2 ), rank, and/or status, which characterizes the change to the manual input  9064 . The processor  9062  may select the second position (P 2 ), rank, and/or status based on the measurement (M 1 ) of the parameter of the end effector  9012  and a second determined value (V 2 ) representing a second manual input (I 2 ). In certain instances, the second position (P 2 ), rank, and/or status may fall inside the desired zone or range. In such instances, the operator may maintain the second manual input (I 2 ) for a remainder of a treatment cycle or procedure, for example. 
     In the aspect illustrated in  FIG.  41   , the controller  9061  includes a storage medium such as, for example, a memory  9068 . The memory  9068  may be configured to store correlations between measurements of one or more parameters of the end effector  9012 , values representing manual inputs, and corresponding positions, ranks, and/or statuses characterizing the manual input  9064  with respect to a desired zone or range. In one example, the memory  9068  may store the correlation between the measurement (M 1 ), the first determined value (V 1 ), and the first manual input (I 1 ), and the correlation between the measurement (M 1 ), the second determined value (V 2 ), and the second manual input (I 2 ). In one example, the memory  9068  may store an algorism, an equation, or a look-up table for determining correlations between measurements of one or more parameters of the end effector  9012 , values representing manual inputs, and corresponding positions, ranks, or statuses with respect to a desired zone or range. The processor  9062  may employ such algorism, equation, and/or look-up table to characterize a manual input  9064  provided by an operator of the surgical instrument  9010  and provide feedback to the operator as to the adequacy of the manual input  9064 . 
       FIG.  42    is a logic diagram illustrating one aspect of a real-time feedback system  9070 . The real-time feedback system  9070  is similar in many respects to the real-time feedback system  9060 . For example, like the real-time feedback system  9060 , the real-time feedback system  9070  is configured for assessing, in real-time, a manual input of an operator of the surgical instrument  9010  and providing to the operator real-time feedback as to the adequacy of the manual input. Furthermore, like the real-time feedback system  9060 , the real-time feedback system  9070  is comprised of a circuit that may include the controller  9061 . 
     In the aspect illustrated in  FIG.  42   , a sensor  9072 , such as, for example, a strain gauge or a micro-strain gauge, is configured to measure one or more parameters of the end effector  9012 , such as, for example, the amplitude of the strain exerted on the anvil  9014  during a clamping operation, which can be indicative of the tissue compression. The measured strain is converted to a digital signal and provided to the processor  9062 . A sensor  9074 , such as, for example, a load sensor, can measure the force to advance the cutting member  9040  to cut tissue captured between the anvil  9014  and the staple cartridge  9018 . Alternatively, a current sensor (not shown) can be employed to measure the current drawn by the motor  9082 . The force required to advance the firing bar  9036  can correspond to the current drawn by the motor  9082 , for example. The measured force is converted to a digital signal and provided to the processor  9062 . A sensor  9076 , such as, for example, a magnetic field sensor, can be employed to measure the thickness of the captured tissue, as described above. The measurement of the magnetic field sensor  9076  is also converted to a digital signal and provided to the processor  9062 . 
     In the aspect illustrated in  FIG.  42   , the real-time feedback system  9070  further includes the tracking system  9080  which can be configured to determine the position of the firing trigger. As described above, the firing trigger  9094  can be depressed or actuated by moving the firing trigger  9094  between a plurality of positions, each corresponding to one of a plurality of values of a characteristic of motion of the firing bar  9036  and/or the cutting member  9040  during a firing stroke. As describe above, a characteristic of motion can be a speed of advancement of the firing bar  9036  and/or the cutting member  9040  during the firing stroke. In certain instances, a motor driver  9092  can be in communication with the controller  9061 , and can be configured to drive the motor  9082  in accordance with an operator&#39;s manual input as detected by the tracking system  9080 . 
     Further to the above, the real-time feedback system  9070  may include a feedback indicator  9066 . In one aspect, the feedback indicator  9066  can be disposed in the handle  9030 . Alternatively, the feedback indicator can be disposed in the shaft assembly  9032 , for example. In any event, the controller  9061  may employ the feedback indicator  9066  to provide feedback to an operator of the surgical instrument  9010  with regard to the adequacy of a manual input such as, for example, a selected position of the firing trigger  9094 . To do so, the controller  9061  may assess the selected position of the firing trigger  9094  and/or the corresponding value of the speed of the firing bar  9036  and/or the cutting member  9040 . The measurements of the tissue compression, the tissue thickness, and/or the force required to advance the firing bar  9036 , as respectively measured by the sensors  9072 ,  9074 , and  9076 , can be used by the controller  9061  to characterize the selected position of the firing trigger  9094  and/or the corresponding value of the speed of the firing bar  9036  and/or the cutting member  9040 . In one instance, the memory  9068  may store an algorism, an equation, and/or a look-up table which can be employed by the controller  9061  in the assessment. In one example, the measurements of the sensors  9072 ,  9074 , and/or  9076  can be used to select or determine a position, rank, and/or a status that characterizes the selected position of the firing trigger  9094  and/or the corresponding value of the speed of the firing bar  9036  and/or the cutting member  9040 . The determined position, rank, and/or status can be communicated to the operator via the feedback indicator  9066 . 
     The reader will appreciate that an optimal speed of the firing bar  9036  and/or the cutting member  9040  during a firing stroke can depend on several parameters of the end effector  9012  such as, for example, the thickness of the tissue captured by the end effector  9012 , the tissue compression, and/or the force required to advance the firing bar  9036  and, in turn, the cutting member  9040 . As such, measurements of these parameters can be leveraged by the controller  9061  in assessing whether a current speed of advancement of the cutting member  9040  through the captured tissue is within an optimal zone or range. 
     In one aspect, a plurality of smart sensors may be positioned on a power line of an end-effector and may be communicatively coupled to a handle of an endocutter. The smart sensors may be positioned in series or parallel with respect to the power line. Referring now to  FIG.  43   , smart sensors  12060  and  12062  may be in communication with a signal processing component or a processor  12064  which may be local to the smart sensors. Both the smart sensors  12060  and  12062  and the processor  12064  may be located at the end-effector (represented by dashed-box  12066 ). For example, smart sensor  12060  may output signals or data to an operational amplifier  12068  and an ADC converter  12070 , which may condition the signals or data for input into processor  12064 . Similarly, smart sensor  12062  may output signals or data to an operational amplifier  12072  and an ADC converter  12074 , which may condition the signals or data for input into processor  12064 . 
     Smart sensors  12060  and/or  12062  may be different types of sensors or the same type of sensor, which may be, for example, magnetic field sensors, magnetic sensors, inductive sensors, capacitive sensors, or other types of sensors used in medical devices or endocutters. Component  12064 , previously referred to as a processor, also may be a computational core, FPGA (field programmable gate array), logic unit (e.g., logic processor or logic controller), signal processing unit, or other type of processor. The processor  12064  may be in communication with a memory, such as non-volatile memory  12076 , which may store calculation data, equipment information such as a type of cartridge inserted in the end-effector  12066 , tabular data, or other reference data that may enable the processor  12064  to process signals or data received from one or more of the smart sensors  12060  or  12062  for use in operating the end-effector  12066  or an endocutter. 
     Further, a shaft  12078  may include a return path through which at least one of the plurality of smart sensors (e.g., smart sensors  12060  or  12062 ) and the handle  12080  are communicatively coupled. The shaft may include one or more wires which may transfer information from the processor  12064  to the handle  12080  for operation of the end-effector  12066  or endocutter. In one example, the information from the processor  12064  may be communicated to the handle  12080  (by way of shaft  12078  or directly without use of shaft  12078 ) over one or more of: a wired-line, a single-wired line, a multi-wired line, a wireless communication protocol such as Bluetooth, an optical line, or an acoustic line. 
     In one aspect, at least one of a plurality of smart sensors positioned at an end-effector may include a signal processing component. For example, the signal processing component may be built into the smart sensor or may be locally coupled to the smart sensor as a single module. The signal processing component may be configured to process data received from a sensor component (e.g., sensor component  12020 ) of at least one of the plurality of smart sensors. A controller  12024  (e.g., a controller) at the handle may be communicatively coupled to at least one of the plurality of smart sensors. 
     In one aspect, a smart sensor may be configured for local signal processing in a medical device. The smart sensor may include at least one sensor component (e.g., sensor component  12020 ) and at least one processing component (e.g., processing component  12022 ). The processing component may be configured to receive data from the at least one sensor component and to process the data into information for use by the medical device. The medical device may be, for example, an endocutter, however this is not intended to be a limitation of the present disclosure. It should be understood that the techniques and features discussed herein for smart sensors with local signal processing may be used in any medical device where processing of sensor signals or data is used for operation of the medical device. 
     Further, a controller (e.g., controller  12024 , controller) in the medical device may be configured to receive the information (i.e., processed signals or data) from the at least one processing component (e.g., processing component  12022 ). As discussed above, the medical device may be a surgical instrument such as an endocutter and the smart sensor may be configured for local signal processing in the surgical instrument. Local signal processing may refer to, for example, processing signals or data from a sensor component at a processing component coupled to the sensor, where the resulting processed information may be used by a separate component. For example, the controller  12024  may be positioned in the handle  12012  of the surgical instrument (i.e., the endocutter  12010 ) and the smart sensor may be configured to be positioned in a separate component (i.e., the end-effector  12016 ) of the surgical instrument (i.e., the endocutter  12010 ), separate from the handle  12012 . Thus, the controller  12024  may be positioned at the handle  12012  of the surgical instrument and the signal processing component  12022  and the sensor  12020  may be located in a component separate from the handle  12012  (e.g., end-effector  12016 ). 
     In this way, the handle or controller  12024  need not have information about the smart sensor, knowledge of what the smart sensor is doing, or capability to interpret data feed back from the smart sensor. This is because the processing component  12022  may transform or condition the data from the smart sensor and generate information from the data directly usable by the handle or controller  12024 . The information generated by the processing component may be used directly, without the data from the smart sensor needing to be processed in another part of the medical device (e.g., near the handle  12012  or controller  12024 ). Thus, the surgical instrument may be controlled based on the (processed) information from the signal processing component local to the sensor. 
     In one aspect, a current draw on a power line communicatively coupled to the signal processing component  12022  (i.e., local to the sensor  12020 ) may be monitored. The current draw may be monitored by a processor, controller, or other monitoring device at the shaft  12014  or the handle  12012 , or at another processor, controller or other monitoring device separate from the signal processing component  12022 . For example, the monitoring may be a standard Morse Code type monitoring of the current draw on the power line. An issue with the surgical instrument based on the current draw and a particular sensor may be determined by the separate processor at, e.g., the handle  12012 . In this way, the monitoring may allow the handle (or a processor or controller therein) to be informed of various issues related to signals or data received by one or more sensor and which particular sensor identified the issue, without a further communication requirement (e.g., pairing, or other coupled communication). 
       FIG.  44    illustrates one aspect of a circuit  13190  configured to convert signals from the first sensor  13158  and the plurality of secondary sensors  13160   a ,  13160   b  into digital signals receivable by a processor, such as, for example, the primary processor  2006  ( FIGS.  16 A- 16 B ). The circuit  13190  comprises an analog-to-digital convertor  13194 . In some examples, the analog-to-digital convertor  13194  comprises a 4-channel, 18-bit analog to digital convertor. Those skilled in the art will recognize that the analog-to-digital convertor  13194  may comprise any suitable number of channels and/or bits to convert one or more inputs from analog to digital signals. The circuit  13190  comprises one or more level shifting resistors  13196  configured to receive an input from the first sensor  13158 , such as, for example, a magnetic field sensor. The level shifting resistors  13196  adjust the input from the first sensor, shifting the value to a higher or lower voltage depending on the input. The level shifting resistors  13196  provide the level-shifted input from the first sensor  13158  to the analog-to-digital convertor. 
     In some aspects, a plurality of secondary sensors  13160   a ,  13160   b  are coupled to a plurality of bridges  13192   a ,  13192   b  within the circuit  13190 . The plurality of bridges  13192   a ,  13192   b  may provide filtering of the input from the plurality of secondary sensors  13160   a ,  13160   b . After filtering the input signals, the plurality of bridges  13192   a ,  13192   b  provide the inputs from the plurality of secondary sensors  13160   a ,  13160   b  to the analog-to-digital convertor  13194 . In some examples, a switch  13198  coupled to one or more level shifting resistors may be coupled to the analog-to-digital convertor  13194 . The switch  13198  is configured to calibrate one or more of the input signals, such as, for example, an input from a magnetic field sensor. The switch  13198  may be engaged to provide one or more level shifting signals to adjust the input of one or more of the sensors, such as, for example, to calibrate the input of a magnetic field sensor. In some examples, the adjustment is not necessary, and the switch  13198  is left in the open position to decouple the level shifting resistors. The switch  13198  is coupled to the analog-to-digital convertor  13194 . The analog-to-digital convertor  13194  provides an output to one or more processors, such as, for example, the primary processor  2006  ( FIGS.  16 A- 16 B ). The primary processor  2006  calculates one or more parameters of the end effector  13150  based on the input from the analog-to-digital convertor  13194 . For example, in one example, the primary processor  2006  calculates a thickness of tissue located between the anvil  13152  and the staple cartridge  13156  based on inputs from the first sensor  13158  and the plurality of secondary sensors  13160   a ,  13160   b.    
       FIG.  45    illustrates one aspect of a staple cartridge  13606  that comprises a flex cable  13630  connected to a magnetic field sensor  13610  and processor  13612 . The staple cartridge  13606  is similar to the staple cartridge  13606  is similar to the surgical staple cartridge  304  ( FIG.  1   ) described above in connection with surgical instrument  10  ( FIGS.  1 - 6   ).  FIG.  112    is an exploded view of the staple cartridge  13606 . The staple cartridge comprises  13606  a cartridge body  13620 , a wedge sled  13618 , a cartridge tray  13622 , and a flex cable  13630 . The flex cable  13630  further comprises electrical contacts  13632  at the proximal end of the staple cartridge  13606 , placed to make an electrical connection when the staple cartridge  13606  is operatively coupled with an end effector, such as end effector  13800  described below. The electrical contacts  13632  are integrated with cable traces  13634 , which extend along some of the length of the staple cartridge  13606 . The cable traces  13634  connect  13636  near the distal end of the staple cartridge  13606  and this connection  13636  joins with a conductive coupling  13614 . A magnetic field sensor  13610  and a processor  13612  are operatively coupled to the conductive coupling  13614  such that the magnetic field sensor  13610  and the processor  13612  are able to communicate. 
       FIG.  46    illustrates one aspect of an end effector  13800  with a flex cable  13830  operable to provide power to a staple cartridge  13806  that comprises a distal sensor plug  13816 . The end effector  13800  is similar to the end effector  300  ( FIG.  1   ) described above in connection with surgical instrument  10  ( FIGS.  1 - 6   ). The end effector  13800  comprises an anvil  13802 , a jaw member or elongated channel  13804 , and a staple cartridge  13806  operatively coupled to the elongated channel  13804 . The end effector  13800  is operatively coupled to a shaft assembly. The shaft assembly is similar to interchangeable shaft assembly  200  ( FIG.  1   ) described above in connection with surgical instrument  10  ( FIGS.  1 - 6   ). The shaft assembly further comprises a closure tube that encloses the exterior of the shaft assembly. In some examples the shaft assembly further comprises an articulation joint  13904 , which includes a double pivot closure sleeve assembly. The double pivot closure sleeve assembly includes an end effector closure sleeve assembly that is operable to couple with the end effector  13800 . 
       FIGS.  47  and  48    illustrate the elongated channel  13804  portion of the end effector  13800  without the anvil  13802  or the staple cartridge, to illustrate how the flex cable  13830  can be seated within the elongated channel  13804 . In some examples, the elongated channel  13804  further comprises a third aperture  13824  for receiving the flex cable  13830 . Within the body of the elongated channel  13804  the flex cable splits  13834  to form extensions  13836  on either side of the elongated channel  13804 .  FIG.  48    further illustrates that connectors  13838  can be operatively coupled to the flex cable extensions  13836 . 
       FIG.  49    illustrates the flex cable  13830  alone. As illustrated, the flex cable  13830  comprises a single coil  13832  operative to wrap around the articulation joint  13904  ( FIG.  46   ), and a split  13834  that attaches to extensions  13836 . The extensions can be coupled to connectors  13838  that have on their distal facing surfaces prongs  13840  for coupling to the staple cartridge  13806 , as described below. 
       FIG.  50    illustrates a close up view of the elongated channel  13804  shown in  FIGS.  47  and  48    with a staple cartridge  13804  coupled thereto. The staple cartridge  13804  comprises a cartridge body  13822  and a cartridge tray  13820 . In some examples the staple cartridge  13806  further comprises electrical traces  13828  that are coupled to proximal contacts  13856  at the proximal end of the staple cartridge  13806 . The proximal contacts  13856  can be positioned to form a conductive connection with the prongs  13840  of the connectors  13838  that are coupled to the flex cable extensions  13836 . Thus, when the staple cartridge  13806  is operatively coupled with the elongated channel  13804 , the flex cable  13830 , through the connectors  13838  and the connector prongs  13840 , can provide power to the staple cartridge  13806 . 
       FIGS.  51  and  52    illustrate one aspect of a distal sensor plug  13816 .  FIG.  51    illustrates a cutaway view of the distal sensor plug  13816 . As illustrated, the distal sensor plug  13816  comprises a magnetic field sensor  13810  and a processor  13812 . The distal sensor plug  13816  further comprises a flex board  13814 . As further illustrated in  FIG.  52   , the magnetic field sensor  13810  and the processor  13812  are operatively coupled to the flex board  13814  such that they are capable of communicating. 
       FIG.  53    illustrates one aspect of an end effector  13950  with a flex cable  13980  operable to provide power to sensors and electronics in the distal tip  13952  of the anvil  13961  portion. The end effector  13950  comprises an anvil  13961 , a jaw member or elongated channel  13954 , and a staple cartridge  13956  operatively coupled to the elongated channel. The end effector  13950  is operatively coupled to a shaft assembly  13960 . The shaft assembly  13960  further comprises a closure tube  13962  that encloses the shaft assembly  13960 . In some examples the shaft assembly  13960  further comprises an articulation joint  13964 , which includes a double pivot closure sleeve assembly  13966 . 
     In various aspects, the end effector  13950  further comprises a flex cable  13980  that is configured to not interfere with the function of the articulation joint  13964 . In some examples, the closure tube  13962  comprises a first aperture  13968  through which the flex cable  13980  can extend. In some examples, flex cable  13980  further comprises a loop or coil  13982  that wraps around the articulation joint  13964  such that the flex cable  13980  does not interfere with the operation of the articulation joint  13964 , as further described below. In some examples, the flex cable  13980  extends along the length of the anvil  13961  to a second aperture  13970  in the distal tip of the anvil  13961 . 
     A portion of a surgical stapling instrument  16000  is illustrated in  FIGS.  54 - 56   . The stapling instrument  16000  is usable with a manually-operated system and/or a robotically-controlled system, for example. The stapling instrument  16000  comprises a shaft  16010  and an end effector  16020  extending from the shaft  16010 . The end effector  16020  comprises a cartridge channel  16030  and a staple cartridge  16050  positioned in the cartridge channel  16030 . The staple cartridge  16050  comprises a cartridge body  16051  and a retainer  16057  attached to the cartridge body  16051 . The cartridge body  16051  is comprised of a plastic material, for example, and the retainer  16057  is comprised of metal, for example; however, the cartridge body  16051  and the retainer  16057  can be comprised of any suitable material. The cartridge body  16051  comprises a deck  16052  configured to support tissue, a longitudinal slot  16056 , and a plurality of staple cavities  16053  defined in the deck  16052 . 
     Referring primarily to  FIGS.  55  and  56   , staples  16055  are removably positioned in the staple cavities  16053  and are supported by staple drivers  16054  which are also movably positioned in the staple cavities  16053 . The retainer  16057  extends around the bottom of the cartridge body  16051  to keep the staple drivers  16054  and/or the staples  16055  from falling out of the bottom of the staple cavities  16053 . The staple drivers  16054  and the staples  16055  are movable between an unfired position ( FIG.  55   ) and a fired position by a sled  16060 . The sled  16060  is movable between a proximal, unfired position ( FIG.  55   ) toward a distal, fired position to eject the staples  16055  from the staple cartridge  16050 , as illustrated in  FIG.  56   . The sled  16060  comprises one or more ramped surfaces  16064  which are configured to slide under the staple drivers  16054 . The end effector  16020  further comprises an anvil  16040  configured to deform the staples  16055  when the staples  16055  are ejected from the staple cartridge  16050 . In various instances, the anvil  16040  can comprise forming pockets  16045  defined therein which are configured to deform the staples  16055 . 
     The shaft  16010  comprises a frame  16012  and an outer sleeve  16014  which is movable relative to the frame  16012 . The cartridge channel  16030  is mounted to and extends from the shaft frame  16012 . The outer sleeve  16014  is operably engaged with the anvil  16040  and is configured to move the anvil  16040  between an open position ( FIG.  54   ) and a closed position ( FIG.  55   ). In use, the anvil  16040  is movable toward a staple cartridge  16050  positioned in the cartridge channel  16030  to clamp tissue against the deck  16052  of the staple cartridge  16050 . In various alternative aspects, the cartridge channel  16030  and the staple cartridge  16050  are movable relative to the anvil  16040  to clamp tissue therebetween. In either event, the shaft  16010  further comprises a firing member  16070  configured to push the sled  16060  distally. The firing member  16070  comprises a knife edge  16076  which is movable within the longitudinal slot  16056  and is configured to incise the tissue positioned intermediate the anvil  16040  and the staple cartridge  16050  as the firing member  16070  is advanced distally to eject the staples  16055  from the staple cartridge  16050 . The firing member  16070  further comprises a first cam  16071  configured to engage the cartridge channel  16030  and a second cam  16079  configured to engage the anvil  16040  and hold the anvil  16040  in position relative to the staple cartridge  16050 . The first cam  16071  is configured to slide under the cartridge channel  16030  and the second cam  16079  is configured to slide within an elongated slot  16049  defined in the anvil  16040 . 
       FIG.  57    illustrates one aspect of an end effector  3011  comprising a first sensor  3008   a  and a second sensor  3008   b . The end effector  3011  is similar to the end effector  300  described above. The end effector  3011  comprises an anvil  3013  pivotally coupled to a jaw member  3004 . The jaw member  3004  is configured to receive a staple cartridge  3021  therein. The staple cartridge  3021  comprises a plurality of staples (not shown). The plurality of staples is deployable from the staple cartridge  3021  during a surgical operation. The end effector  3011  comprises a first sensor  3008   a  configured to measure one or more parameters of the end effector  3011 . For example, in one aspect, the first sensor  3008   a  is configured to measure the gap  3023  between the anvil  3013  and the jaw member  3004 . The first sensor  3008   a  may comprise, for example, a Hall effect sensor configured to detect a magnetic field generated by a magnet  3012  embedded in the second jaw member  3004  and/or the staple cartridge  3021 . As another example, in one aspect, the first sensor  3008   a  is configured to measure one or more forces exerted on the anvil  3013  by the second jaw member  3004  and/or tissue clamped between the anvil  3013  and the second jaw member  3004 . 
     The end effector  3011  comprises a second sensor  3008   b . The second sensor  3008   b  is configured to measure one or more parameters of the end effector  3011 . For example, in various aspects, the second sensor  3008   b  may comprise a strain gauge configured to measure the magnitude of the strain in the anvil  3013  during a clamped condition. The strain gauge provides an electrical signal whose amplitude varies with the magnitude of the strain. In various aspects, the first sensor  3008   a  and/or the second sensor  3008   b  may comprise, for example, a magnetic sensor such as, for example, a Hall effect sensor, a strain gauge, a pressure sensor, a force sensor, an inductive sensor such as, for example, an eddy current sensor, a resistive sensor, a capacitive sensor, an optical sensor, and/or any other suitable sensor for measuring one or more parameters of the end effector  3011 . The first sensor  3008   a  and the second sensor  3008   b  may be arranged in a series configuration and/or a parallel configuration. In a series configuration, the second sensor  3008   b  may be configured to directly affect the output of the first sensor  3008   a . In a parallel configuration, the second sensor  3008   b  may be configured to indirectly affect the output of the first sensor  3008   a.    
     In one aspect, the one or more parameters measured by the first sensor  3008   a  are related to the one or more parameters measured by the second sensor  3008   b . For example, in one aspect, the first sensor  3008   a  is configured to measure the gap  3023  between the anvil  3013  and the jaw member  3004 . The gap  3023  is representative of the thickness and/or compressibility of a tissue section clamped between the anvil  3013  and the staple cartridge  3021  located in the jaw member  3004 . The first sensor  3008   a  may comprise, for example, a Hall effect sensor configured to detect a magnetic field generated by a magnet  3012  coupled to the second jaw member  3004  and/or the staple cartridge  3021 . Measuring at a single location accurately describes the compressed tissue thickness for a calibrated full bit of tissue, but may provide inaccurate results when a partial bite of tissue is placed between the anvil  3013  and the second jaw member  3004 . A partial bite of tissue, either a proximal partial bite or a distal partial bite, changes the clamping geometry of the anvil  3013 . 
     In some aspects, the second sensor  3008   b  is configured to detect one or more parameters indicative of a type of tissue bite, for example, a full bite, a partial proximal bite, and/or a partial distal bite. The measurement of the second sensor  3008   b  may be used to adjust the measurement of the first sensor  3008   a  to accurately represent a proximal or distal positioned partial bite&#39;s true compressed tissue thickness. For example, in one aspect, the second sensor  3008   b  comprises a strain gauge, such as, for example, a micro-strain gauge, configured to monitor the amplitude of the strain in the anvil during a clamped condition. The amplitude of the strain of the anvil  3013  is used to modify the output of the first sensor  3008   a , for example, a Hall effect sensor, to accurately represent a proximal or distal positioned partial bite&#39;s true compressed tissue thickness. The first sensor  3008   a  and the second sensor  3008   b  may be measured in real-time during a clamping operation. Real-time measurement allows time based information to be analyzed, for example, by the primary processor  2006 , and used to select one or more algorithms and/or look-up tables to recognize tissue characteristics and clamping positioning to dynamically adjust tissue thickness measurements. 
     In some aspects, the thickness measurement of the first sensor  3008   a  may be provided to an output device of a surgical instrument  10  coupled to the end effector  3011 . For example, in one aspect, the end effector  3011  is coupled to the surgical instrument  10  comprising a display  2028 . The measurement of the first sensor  3008   a  is provided to a processor, for example, the primary processor  2006 . The primary processor  2006  adjusts the measurement of the first sensor  3008   a  based on the measurement of the second sensor  3008   b  to reflect the true tissue thickness of a tissue section clamped between the anvil  3013  and the staple cartridge  3021 . The primary processor  2006  outputs the adjusted tissue thickness measurement and an indication of full or partial bite to the display  2028 . An operator may determine whether or not to deploy the staples in the staple cartridge  3021  based on the displayed values. 
     In some aspects, the first sensor  3008   a  and the second sensor  3008   b  may be located in different environments, such as, for example, the first sensor  3008   a  being located within a patient at a treatment site and the second sensor  3008   b  being located externally to the patient. The second sensor  3008   b  may be configured to calibrate and/or modify the output of the first sensor  3008   a . The first sensor  3008   a  and/or the second sensor  3008   b  may comprise, for example, an environmental sensor. Environmental sensors may comprise, for example, temperature sensors, humidity sensors, pressure sensors, and/or any other suitable environmental sensor. 
       FIG.  58    is a logic diagram illustrating one aspect of a process  3050  for determining and displaying the thickness of a tissue section clamped between the anvil  3013  and the staple cartridge  3021  of the end effector  3011 . The process  3050  comprises obtaining a Hall effect voltage  3052 , for example, through a Hall effect sensor located at the distal tip of the anvil  3013 . The Hall effect voltage  3052  is provided to an analog to digital convertor  3054  and converted into a digital signal. The digital signal is provided to a processor, such as, for example, the primary processor  2006 . The primary processor  2006  calibrates  3056  the curve input of the Hall effect voltage  3052  signal. A strain gauge  3058 , such as, for example, a micro-strain gauge, is configured to measure one or more parameters of the end effector  3011 , such as, for example, the amplitude of the strain exerted on the anvil  3013  during a clamping operation. The measured strain is converted  3060  to a digital signal and provided to the processor, such as, for example, the primary processor  2006 . The primary processor  2006  uses one or more algorithms and/or lookup tables to adjust the Hall effect voltage  3052  in response to the strain measured by the strain gauge  3058  to reflect the true thickness and fullness of the bite of tissue clamped by the anvil  3013  and the staple cartridge  3021 . The adjusted thickness is displayed  3026  to an operator by, for example, a display  2026  embedded in the surgical instrument  10 . 
     In some aspects, the surgical instrument can further comprise a load sensor  3082  or load cell. The load sensor  3082  can be located, for instance, in the interchangeable shaft assembly  200 , described above, or in the housing  12 , also described above. 
       FIG.  59    is a logic diagram illustrating one aspect of a process  3070  for determining and displaying the thickness of a tissue section clamped between the anvil  3013  and the staple cartridge  3021  of the end effector  3011 . The process comprises obtaining a Hall effect voltage  3072 , for example, through a Hall effect sensor located at the distal tip of the anvil  3013 . The Hall effect voltage  3072  is provided to an analog to digital convertor  3074  and converted into a digital signal. The digital signal is provided to a processor, such as, for example, the primary processor  2006 . The primary processor  2006  applies calibrates  3076  the curve input of the Hall effect voltage  3072  signal. A strain gauge  3078 , such as, for example, a micro-strain gauge, is configured to measure one or more parameters of the end effector  3011 , such as, for example, the amplitude of the strain exerted on the anvil  3013  during a clamping operation. The measured strain is converted  3080  to a digital signal and provided to the processor, such as, for example, the primary processor  2006 . The load sensor  3082  measures the clamping force of the anvil  3013  against the staple cartridge  3021 . The measured clamping force is converted  3084  to a digital signal and provided to the processor, such as for example, the primary processor  2006 . The primary processor  2006  uses one or more algorithms and/or lookup tables to adjust the Hall effect voltage  3072  in response to the strain measured by the strain gauge  3078  and the clamping force measured by the load sensor  3082  to reflect the true thickness and fullness of the bite of tissue clamped by the anvil  3013  and the staple cartridge  3021 . The adjusted thickness is displayed  3026  to an operator by, for example, a display  2026  embedded in the surgical instrument  10 . 
       FIG.  60    illustrates one aspect of an end effector  3100  comprising a first sensor  3108   a  and a second sensor  3108   b . The end effector  3100  is similar to the end effector  3011 . The end effector  3100  comprises an anvil, or anvil,  3102  pivotally coupled to a jaw member  3104 . The jaw member  3104  is configured to receive a staple cartridge  3106  therein. The end effector  3100  comprises a first sensor  3108   a  coupled to the anvil  3102 . The first sensor  3108   a  is configured to measure one or more parameters of the end effector  3100 , such as, for example, the gap  3110  between the anvil  3102  and the staple cartridge  3106 . The gap  3110  may correspond to, for example, a thickness of tissue clamped between the anvil  3102  and the staple cartridge  3106 . The first sensor  3108   a  may comprise any suitable sensor for measuring one or more parameters of the end effector. For example, in various aspects, the first sensor  3108   a  may comprise a magnetic sensor, such as a Hall effect sensor, a strain gauge, a pressure sensor, an inductive sensor, such as an eddy current sensor, a resistive sensor, a capacitive sensor, an optical sensor, and/or any other suitable sensor. 
     In some aspects, the end effector  3100  comprises a second sensor  3108   b . The second sensor  3108   b  is coupled to jaw member  3104  and/or the staple cartridge  3106 . The second sensor  3108   b  is configured to detect one or more parameters of the end effector  3100 . For example, in some aspects, the second sensor  3108   b  is configured to detect one or more instrument conditions such as, for example, a color of the staple cartridge  3106  coupled to the jaw member  3104 , a length of the staple cartridge  3106 , a clamping condition of the end effector  3100 , the number of uses/number of remaining uses of the end effector  3100  and/or the staple cartridge  3106 , and/or any other suitable instrument condition. The second sensor  3108   b  may comprise any suitable sensor for detecting one or more instrument conditions, such as, for example, a magnetic sensor, such as a Hall effect sensor, a strain gauge, a pressure sensor, an inductive sensor, such as an eddy current sensor, a resistive sensor, a capacitive sensor, an optical sensor, and/or any other suitable sensor. 
     In one aspect, input from the second sensor  3108   b  may be used to calibrate the input of the first sensor  3108   a . The second sensor  3108   b  may be configured to detect one or more parameters of the staple cartridge  3106 , such as, for example, the color and/or length of the staple cartridge  3106 . The detected parameters, such as the color and/or the length of the staple cartridge  3106 , may correspond to one or more properties of the cartridge, such as, for example, the height of the cartridge deck, the thickness of tissue useable/optimal for the staple cartridge, and/or the pattern of the staples in the staple cartridge  3106 . The known parameters of the staple cartridge  3106  may be used to adjust the thickness measurement provided by the first sensor  3108   a . For example, if the staple cartridge  3106  has a higher deck height, the thickness measurement provided by the first sensor  3108   a  may be reduced to compensate for the added deck height. The adjusted thickness may be displayed to an operator, for example, through a display  2026  coupled to the surgical instrument  10 . 
       FIG.  61    illustrates one aspect of an end effector  3150  comprising a first sensor  3158  and a plurality of secondary sensors  3160   a ,  3160   b . The end effector  3150  comprises an anvil, or anvil,  3152  and a jaw member  3154 . The jaw member  3154  is configured to receive a staple cartridge  3156 . The anvil  3152  is pivotally moveable with respect to the jaw member  3154  to clamp tissue between the anvil  3152  and the staple cartridge  3156 . The anvil comprises a first sensor  3158 . The first sensor  3158  is configured to detect one or more parameters of the end effector  3150 , such as, for example, the gap  3110  between the anvil  3152  and the staple cartridge  3156 . The gap  3110  may correspond to, for example, a thickness of tissue clamped between the anvil  3152  and the staple cartridge  3156 . The first sensor  3158  may comprise any suitable sensor for measuring one or more parameters of the end effector. For example, in various aspects, the first sensor  3158  may comprise a magnetic sensor, such as a Hall effect sensor, a strain gauge, a pressure sensor, an inductive sensor, such as an eddy current sensor, a resistive sensor, a capacitive sensor, an optical sensor, and/or any other suitable sensor. 
     In some aspects, the end effector  3150  comprises a plurality of secondary sensors  3160   a ,  3160   b . The secondary sensors  3160   a ,  3160   b  are configured to detect one or more parameters of the end effector  3150 . For example, in some aspects, the secondary sensors  3160   a ,  3160   b  are configured to measure an amplitude of strain exerted on the anvil  3152  during a clamping procedure. In various aspects, the secondary sensors  3160   a ,  3160   b  may comprise a magnetic sensor, such as a Hall effect sensor, a strain gauge, a pressure sensor, an inductive sensor, such as an eddy current sensor, a resistive sensor, a capacitive sensor, an optical sensor, and/or any other suitable sensor. The secondary sensors  3160   a ,  3160   b  may be configured to measure one or more identical parameters at different locations of the anvil  3152 , different parameters at identical locations on the anvil  3152 , and/or different parameters at different locations on the anvil  3152 . 
       FIG.  62    illustrates one aspect of an end effector  3200  comprising a plurality of sensors  3208   a - 3208   d . The end effector  3200  comprises an anvil  3202  pivotally coupled to a jaw member  3204 . The jaw member  3204  is configured to receive a staple cartridge  3206  therein. The anvil  3202  comprises a plurality of sensors  3208   a - 3208   d  thereon. The plurality of sensors  3208   a - 3208   d  is configured to detect one or more parameters of the end effector  3200 , such as, for example, the anvil  3202 . The plurality of sensors  3208   a - 3208   d  may comprise one or more identical sensors and/or different sensors. The plurality of sensors  3208   a - 3208   d  may comprise, for example, magnetic sensors, such as a Hall effect sensor, strain gauges, pressure sensors, inductive sensors, such as an eddy current sensor, resistive sensors, capacitive sensors, optical sensors, and/or any other suitable sensors or combination thereof. For example, in one aspect, the plurality of sensors  3208   a - 3208   d  may comprise a plurality of strain gauges. 
     In one aspect, the plurality of sensors  3208   a - 3208   d  allows a robust tissue thickness sensing process to be implemented. By detecting various parameters along the length of the anvil  3202 , the plurality of sensors  3208   a - 3208   d  allow a surgical instrument, such as, for example, the surgical instrument  10 , to calculate the tissue thickness in the jaws regardless of the bite, for example, a partial or full bite. In some aspects, the plurality of sensors  3208   a - 3208   d  comprises a plurality of strain gauges. The plurality of strain gauges is configured to measure the strain at various points on the anvil  3202 . The amplitude and/or the slope of the strain at each of the various points on the anvil  3202  can be used to determine the thickness of tissue in between the anvil  3202  and the staple cartridge  3206 . The plurality of strain gauges may be configured to optimize maximum amplitude and/or slope differences based on clamping dynamics to determine thickness, tissue placement, and/or material properties of the tissue. Time based monitoring of the plurality of sensors  3208   a - 3208   d  during clamping allows a processor, such as, for example, the primary processor  2006 , to utilize algorithms and look-up tables to recognize tissue characteristics and clamping positions and dynamically adjust the end effector  3200  and/or tissue clamped between the anvil  3202  and the staple cartridge  3206 . 
       FIG.  63    is a logic diagram illustrating one aspect of a process  3220  for determining one or more tissue properties based on a plurality of sensors  3208   a - 3208   d . In one aspect, a plurality of sensors  3208   a - 3208   d  generate  3222   a - 3222   d  a plurality of signals indicative of one or more parameters of the end effector  3200 . The plurality of generated signals is converted  3224   a - 3224   d  to digital signals and provided to a processor. For example, in one aspect comprising a plurality of strain gauges, a plurality of electronic μStrain (micro-strain) conversion circuits convert  3224   a - 3224   d  the strain gauge signals to digital signals. The digital signals are provided to a processor, such as, for example, the primary processor  2006 . The primary processor  2006  determines  3226  one or more tissue characteristics based on the plurality of signals. The primary processor  2006  may determine the one or more tissue characteristics by applying an algorithm and/or a look-up table. The one or more tissue characteristics are displayed  3026  to an operator, for example, by a display  2026  embedded in the surgical instrument  10 . 
       FIG.  64    illustrates one aspect of an end effector  3250  comprising a plurality of secondary sensors  3260   a - 3260   d  coupled to a jaw member  3254 . The end effector  3250  comprises an anvil  3252  pivotally coupled to a jaw member  3254 . The anvil  3252  is moveable relative to the jaw member  3254  to clamp one or more materials, such as, for example, a tissue section  3264 , therebetween. The jaw member  3254  is configured to receive a staple cartridge  3256 . A first sensor  3258  is coupled to the anvil  3252 . The first sensor is configured to detect one or more parameters of the end effector  3150 , such as, for example, the gap  3110  between the anvil  3252  and the staple cartridge  3256 . The gap  3110  may correspond to, for example, a thickness of tissue clamped between the anvil  3252  and the staple cartridge  3256 . The first sensor  3258  may comprise any suitable sensor for measuring one or more parameters of the end effector. For example, in various aspects, the first sensor  3258  may comprise a magnetic sensor, such as a Hall effect sensor, a strain gauge, a pressure sensor, an inductive sensor, such as an eddy current sensor, a resistive sensor, a capacitive sensor, an optical sensor, and/or any other suitable sensor. 
     A plurality of secondary sensors  3260   a - 3260   d  is coupled to the jaw member  3254 . The plurality of secondary sensors  3260   a - 3260   d  may be formed integrally with the jaw member  3254  and/or the staple cartridge  3256 . For example, in one aspect, the plurality of secondary sensors  3260   a - 3260   d  is disposed on an outer row of the staple cartridge  3256  (see  FIG.  63   ). The plurality of secondary sensors  3260   a - 3260   d  are configured to detect one or more parameters of the end effector  3250  and/or a tissue section  3264  clamped between the anvil  3252  and the staple cartridge  3256 . The plurality of secondary sensors  3260   a - 3260   d  may comprise any suitable sensors for detecting one or more parameters of the end effector  3250  and/or the tissue section  3264 , such as, for example, magnetic sensors, such as a Hall effect sensor, strain gauges, pressure sensors, inductive sensors, such as an eddy current sensor, resistive sensors, capacitive sensors, optical sensors, and/or any other suitable sensors or combination thereof. The plurality of secondary sensors  3260   a - 3260   d  may comprise identical sensors and/or different sensors. 
     In some aspects, the plurality of secondary sensors  3260   a - 3260   d  comprises dual purpose sensors and tissue stabilizing elements. The plurality of secondary sensors  3260   a - 3260   d  comprise electrodes and/or sensing geometries configured to create a stabilized tissue condition when the plurality of secondary sensors  3260   a - 3260   d  are engaged with a tissue section  3264 , such as, for example, during a clamping operation. In some aspects, one or more of the plurality of secondary sensors  3260   a - 3260   d  may be replaced with non-sensing tissue stabilizing elements. The secondary sensors  3260   a - 3260   d  create a stabilized tissue condition by controlling tissue flow, staple formation, and/or other tissue conditions during a clamping, stapling, and/or other treatment process. 
       FIG.  65    illustrates one aspect of a staple cartridge  3270  comprising a plurality of sensors  3272   a - 3272   h  formed integrally therein. The staple cartridge  3270  comprises a plurality of rows containing a plurality of holes for storing staples therein. One or more of the holes in the outer row  3278  are replaced with one of the plurality of sensors  3272   a - 3272   h . A cut-away section  3274  is shown to illustrate a sensor  3272   f  coupled to a sensor wire  3276   b . The sensor wires  3276   a ,  3276   b  may comprise a plurality of wires for coupling the plurality of sensors  3272   a - 3272   h  to one or more circuits of a surgical instrument, such as, for example, the surgical instrument  10 . In some aspects, one or more of the plurality of sensors  3272   a - 3272   h  comprise dual purpose sensor and tissue stabilizing elements having electrodes and/or sensing geometries configured to provide tissue stabilization. In some aspects, the plurality of sensors  3272   a - 3272   h  may be replaced with and/or co-populated with a plurality of tissue stabilizing elements. Tissue stabilization may be provided by, for example, controlling tissue flow and/or staple formation during a clamping and/or stapling process. The plurality of sensors  3272   a - 3272   h  provide signals to one or more circuits of the surgical instrument  10  to enhance feedback of stapling performance and/or tissue thickness sensing. 
       FIG.  66    is a logic diagram illustrating one aspect of a process  3280  for determining one or more parameters of a tissue section  3264  clamped within an end effector, such as, for example, the end effector  3250  illustrated in  FIG.  64   . In one aspect, a first sensor  3258  is configured to detect one or more parameters of the end effector  3250  and/or a tissue section  3264  located between the anvil  3252  and the staple cartridge  3256 . A first signal is generated  3282  by the first sensors  3258 . The first signal is indicative of the one or more parameters detected by the first sensor  3258 . One or more secondary sensors  3260  are configured to detect one or more parameters of the end effector  3250  and/or the tissue section  3264 . The secondary sensors  3260  may be configured to detect the same parameters, additional parameters, or different parameters as the first sensor  3258 . Secondary signals  3284  are generated by the secondary sensors  3260 . The secondary signals  3284  are indicative of the one or more parameters detected by the secondary sensors  3260 . The first signal and the secondary signals are provided to a processor, such as, for example, a primary processor  2006 . The primary processor  2006  adjusts  3286  the first signal generated by the first sensor  3258  based on input generated by the secondary sensors  3260 . The adjusted signal may be indicative of, for example, the true thickness of a tissue section  3264  and the fullness of the bite. The adjusted signal is displayed  3026  to an operator by, for example, a display  2026  embedded in the surgical instrument  10 . 
       FIG.  67    illustrates one aspect of an end effector  3350  comprising a magnetic sensor  3358  comprising a specific sampling rate to limit or eliminate false signals. The end effector  3350  comprises an anvil, or anvil,  3352  pivotably coupled to a jaw member  3354 . The jaw member  3354  is configured to receive a staple cartridge  3356  therein. The staple cartridge  3356  contains a plurality of staples that may be delivered to a tissue section located between the anvil  3352  and the staple cartridge  3356 . A magnetic sensor  3358  is coupled to the anvil  3352 . The magnetic sensor  3358  is configured to detect one or more parameters of the end effector  3350 , such as, for example, the gap  3364  between the anvil  3352  and the staple cartridge  3356 . The gap  3364  may correspond to the thickness of a material, such as, for example, a tissue section, and/or the fullness of a bite of material located between the anvil  3352  and the staple cartridge  3356 . The magnetic sensor  3358  may comprise any suitable sensor for detecting one or more parameters of the end effector  3350 , such as, for example, a magnetic sensor, such as a Hall effect sensor, a strain gauge, a pressure sensor, an inductive sensor, such as an eddy current sensor, a resistive sensor, a capacitive sensor, an optical sensor, and/or any other suitable sensor. 
     In one aspect, the magnetic sensor  3358  comprises a magnetic sensor configured to detect a magnetic field generated by an electromagnetic source  3360  coupled to the jaw member  3354  and/or the staple cartridge  3356 . The electromagnetic source  3360  generates a magnetic field detected by the magnetic sensor  3358 . The strength of the detected magnetic field may correspond to, for example, the thickness and/or fullness of a bite of tissue located between the anvil  3352  and the staple cartridge  3356 . In some aspects, the electromagnetic source  3360  generates a signal at a known frequency, such as, for example, 1 MHz. In other aspects, the signal generated by the electromagnetic source  3360  may be adjustable based on, for example, the type of staple cartridge  3356  installed in the jaw member  3354 , one or more additional sensor, an algorithm, and/or one or more parameters. 
     In one aspect, a signal processor  3362  is coupled to the end effector  3350 , such as, for example, the anvil  3352 . The signal processor  3362  is configured to process the signal generated by the magnetic sensor  3358  to eliminate false signals and to boost the input from the magnetic sensor  3358 . In some aspects, the signal processor  3362  may be located separately from the end effector  3350 , such as, for example, in the handle assembly  14  of a surgical instrument  10 . In some aspects, the signal processor  3362  is formed integrally with and/or comprises an algorithm executed by a general processor, such as, for example, the primary processor  2006 . The signal processor  3362  is configured to process the signal from the magnetic sensor  3358  at a frequency substantially equal to the frequency of the signal generated by the electromagnetic source  3360 . For example, in one aspect, the electromagnetic source  3360  generates a signal at a frequency of 1 MHz. The signal is detected by the magnetic sensor  3358 . The magnetic sensor  3358  generates a signal indicative of the detected magnetic field which is provided to the signal processor  3362 . The signal is processed by the signal processor  3362  at a frequency of 1 MHz to eliminate false signals. The processed signal is provided to a processor, such as, for example, the primary processor  2006 . The primary processor  2006  correlates the received signal to one or more parameters of the end effector  3350 , such as, for example, the gap  3364  between the anvil  3352  and the staple cartridge  3356 . 
       FIG.  68    is a logic diagram illustrating one aspect of a process  3370  for generating a thickness measurement for a tissue section located between an anvil and a staple cartridge of an end effector, such as, for example, the end effector  3350  illustrated in  FIG.  45   . In one aspect of the process  3370 , a signal is generated  3372  by a modulated electromagnetic source  3360 . The generated signal may comprise, for example, a 1 MHz signal. A magnetic sensor  3358  is configured to detect  3374  the signal generated by the electromagnetic source  3360 . The magnetic sensor  3358  generates a signal indicative of the detected magnetic field and provides the signal to a signal processor  3362 . The signal processor  3362  processes  3376  the signal to remove noise, false signals, and/or to boost the signal. The processed signal is provided to an analog-to-digital convertor for conversion  3378  to a digital signal. Calibration  3380  of the digital signal may be performed, for example, by application of a calibration curve input algorithm and/or look-up table. The processes  3376 , conversion  3378 , and calibration  3380  may be performed by one or more circuits. The calibrated signal is displayed  3026  to a user by, for example, a display  2026  formed integrally with the surgical instrument  10 . 
       FIGS.  69 A and  69 B  illustrate one aspect of an end effector  3800  comprising a pressure sensor. The end effector  3800  comprises an anvil, or anvil,  3802  pivotally coupled to a jaw member  3804 . The jaw member  3804  is configured to receive a staple cartridge  3806  therein. The staple cartridge  3806  comprises a plurality of staples. A first sensor  3808  is coupled to the anvil  3802  at a distal tip. The first sensor  3808  is configured to detect one or more parameters of the end effector, such as, for example, the distance, or gap  3814 , between the anvil  3802  and the staple cartridge  3806 . The first sensor  3808  may comprise any suitable sensor, such as, for example, a magnetic sensor. A magnet  3810  may be coupled to the jaw member  3804  and/or the staple cartridge  3806  to provide a magnetic signal to the magnetic sensor. 
     In some aspects, the end effector  3800  comprises a second sensor  3812 . The second sensor  3812  is configured to detect one or more parameters of the end effector  3800  and/or a tissue section located therebetween. The second sensor  3812  may comprise any suitable sensor, such as, for example, one or more pressure sensors. The second sensor  3812  may be coupled to the anvil  3802 , the jaw member  3804 , and/or the staple cartridge  3806 . A signal from the second sensor  3812  may be used to adjust the measurement of the first sensor  3808  to adjust the reading of the first sensor to accurately represent proximal and/or distal positioned partial bites true compressed tissue thickness. In some aspects, the second sensor  3812  may be surrogate with respect to the first sensor  3808 . 
     In some aspects, the second sensor  3812  may comprise, for example, a single continuous pressure sensing film and/or an array of pressure sensing films. The second sensor  3812  is coupled to the deck of the staple cartridge  3806  along the central axis covering, for example, a slot  3816  configured to receive a cutting and/or staple deployment member. The second sensor  3812  provides signals indicate of the amplitude of pressure applied by the tissue during a clamping procedure. During firing of the cutting and/or deployment member, the signal from the second sensor  3812  may be severed, for example, by cutting electrical connections between the second sensor  3812  and one or more circuits. In some aspects, a severed circuit of the second sensor  3812  may be indicative of a spent staple cartridge  3806 . In other aspects, the second sensor  3812  may be positioned such that deployment of a cutting and/or deployment member does not sever the connection to the second sensor  3812 . 
       FIG.  70    illustrates one aspect of an end effector  3850  comprising a second sensor  3862  located between a staple cartridge  3806  and a jaw member  3804 . The end effector  3850  comprises an anvil, or anvil,  3852  pivotally coupled to a jaw member  3854 . The jaw member  3854  is configured to receive a staple cartridge  3856  therein. A first sensor  3858  is coupled to the anvil  3852  at a distal tip. The first sensor  3858  is configured to detect one or more parameters of the end effector  3850 , such as, for example, the distance, or gap  3864 , between the anvil  3852  and the staple cartridge  3856 . The first sensor  3858  may comprise any suitable sensor, such as, for example, a magnetic sensor. A magnet  3860  may be coupled to the jaw member  3854  and/or the staple cartridge  3856  to provide a magnetic signal to the magnetic sensor. In some aspects, the end effector  3850  comprises a second sensor  3862  similar in all respect to the second sensor  3812  of  FIGS.  69 A- 69 B , except that it is located between the staple cartridge  3856  and the jaw member  3854 . 
       FIG.  71    is a logic diagram illustrating one aspect of a process  3870  for determining and displaying the thickness of a tissue section clamped in an end effector  3800  or  3850 , according to  FIGS.  69 A- 69 B  or  FIG.  70   . The process comprises obtaining a Hall effect voltage  3872 , for example, through a Hall effect sensor located at the distal tip of the anvil  3802 . The Hall effect voltage  3872  is proved to an analog to digital converter  3876  and converted into a digital signal. The digital signal is provided to a process, such as for example the primary processor  2006 . The primary processor  2006  calibrates  3874  the curve input of the Hall effect voltage  3872  signal. Pressure sensors, such as for example, second sensor  3812 , is configured to measure  3880  one or more parameters of, for example, the end effector  3800 , such as for example the amount of pressure being exerted by the anvil  3802  on the tissue clamped in the end effector  3800 . In some aspects the pressure sensors may comprise a single continuous pressure sensing film and/or array of pressure sensing films. The pressure sensors may thus be operable determine variations in the measure pressure at different locations between the proximal and distal ends of the end effector  3800 . The measured pressure is provided to the processor, such as for example the primary processor  2006 . The primary processor  2006  uses one or more algorithms and/or lookup tables to adjust  3882  the Hall effect voltage  3872  in response to the pressure measured  3880  by the pressure sensors to more accurately reflect the thickness of the tissue clamped between, for example, the anvil  3802  and the staple cartridge  3806 . The adjusted thickness is displayed  3878  to an operator by, for example, a display  2026  embedded in the surgical instrument  10 . 
       FIG.  72    illustrates one aspect of an end effector  3900  comprising a plurality of second sensors  3192   a - 3192   b  located between a staple cartridge  3906  and an elongated channel  3904 . The end effector  3900  comprises an anvil  3902  pivotally coupled to a jaw member or elongated channel  3904 . The elongated channel  3904  is configured to receive a staple cartridge  3906  therein. The anvil  3902  further comprises a first sensor  3908  located in the distal tip. The first sensor  3908  is configured to detect one or more parameters of the end effector  3900 , such as, for example, the distance, or gap, between the anvil  3902  and the staple cartridge  3906 . The first sensor  3908  may comprise any suitable sensor, such as, for example, a magnetic sensor. A magnet  3910  may be coupled to the elongated channel  3904  and/or the staple cartridge  3906  to provide a magnetic signal to the first sensor  3908 . In some aspects, the end effector  3900  comprises a plurality of second sensors  3912   a - 3912   c  located between the staple cartridge  3906  and the elongated channel  3904 . The second sensors  3912   a - 3912   c  may comprise any suitable sensors, such as for instance piezo-resistive pressure film strips. In some aspects, the second sensors  3912   a - 3912   c  may be uniformly distributed between the distal and proximal ends of the end effector  3900 . 
     In some aspects, signals from the second sensors  3912   a - 3912   c  may be used to adjust the measurement of the first sensor  3908 . For instance, the signals from the second sensors  3912   a - 3912   c  may be used to adjust the reading of the first sensor  3908  to accurately represent the gap between the anvil  3902  and the staple cartridge  3906 , which may vary between the distal and proximal ends of the end effector  3900 , depending on the location and/or density of tissue  3920  between the anvil  3902  and the staple cartridge  3906 .  FIG.  11    illustrates an example of a partial bite of tissue  3920 . As illustrated for purposes of this example, the tissue is located only in the proximal area of the end effector  3900 , creating a high pressure  3918  area near the proximal area of the end effector  3900  and a corresponding low pressure  3916  area near the distal end of the end effector. 
       FIGS.  73 A and  73 B  further illustrate the effect of a full versus partial bite of tissue  3920 .  FIG.  73 A  illustrates the end effector  3900  with a full bite of tissue  3920 , where the tissue  3920  is of uniform density. With a full bite of tissue  3920  of uniform density, the measured first gap  3914   a  at the distal tip of the end effector  3900  may be approximately the same as the measured second gap  3922   a  in the middle or proximal end of the end effector  3900 . For example, the first gap  3914   a  may measure 2.4 mm, and the second gap may measure 2.3 mm.  FIG.  73 B  illustrates an end effector  3900  with a partial bite of tissue  3920 , or alternatively a full bit of tissue  3920  of non-uniform density. In this case, the first gap  3914   b  will measure less than the second gap  3922   b  measured at the thickest or densest portion of the tissue  3920 . For example, the first gap may measure 1.0 mm, while the second gap may measure 1.9 mm. In the conditions illustrated in  FIGS.  73 A- 73 B , signals from the second sensors  3912   a - 3912   c , such as for instance measured pressure at different points along the length of the end effector  3900 , may be employed by the instrument to determine tissue  3920  placement and/or material properties of the tissue  3920 . The instrument may further be operable to use measured pressure over time to recognize tissue characteristics and tissue position, and dynamically adjust tissue thickness measurements. 
       FIG.  74    illustrates an aspect of an end effector  4050  that is configured to determine the location of a cutting member or knife  4062 . The end effector  4050  comprises an anvil  4052  pivotally coupled to a jaw member or elongated channel  4054 . The elongated channel  4054  is configured to receive a staple cartridge  4056  therein. The staple cartridge  4056  further comprises a slot (not shown) and a cutting member or knife  4062  located therein. The knife  4062  is operably coupled to a knife bar  4064 . The knife bar  4064  is operable to move the knife  4062  from the proximal end of the slot to the distal end. The end effector  4050  may further comprise an optical sensor  4060  located near the proximal end of the slot. The optical sensor may be coupled to a processor, such as for instance the primary processor  2006 . The optical sensor  4060  may be operable to emit an optical signal towards the knife bar  4064 . The knife bar  4064  may further comprise a code strip  4066  along its length. The code strip  4066  may comprise cut-outs, notches, reflective pieces, or any other configuration that is optically readable. The code strip  4066  is placed such that the optical signal from the optical sensor  4060  will reflect off or through the code strip  4066 . As the knife  4062  moves and knife bar  4064  moves  4068  along the slot  4058 , the optical sensor  4060  will detect the reflection of the emitted optical signal coupled to the code strip  4066 . The optical sensor  4060  may be operable to communicate the detected signal to the primary processor  2006 . The primary processor  2006  may be configured to use the detected signal to determine the position of the knife  4062 . The position of the knife  4062  may be sensed more precisely by designing the code strip  4066  such that the detected optical signal has a gradual rise and fall. 
       FIG.  75    illustrates an example of the code strip  4066  in operation with red LEDs  4070  and infrared LEDs  4072 . For purposes of this example only, the code strip  4066  comprises cut-outs. As the code strip  4066  moves  4068 , the light emitted by the red LEDs  4070  will be interrupted as the cut-outs passed before it. The infrared LEDs  4072  will therefore detect the motion of the code strip  4066 , and therefore, by extension, the motion of the knife  4062 . 
       FIG.  76    depicts a partial view of the end effector  300  of the surgical instrument  10 . In the example form depicted in  FIG.  76   , the end effector  300  comprises a staple cartridge  1100  which is similar in many respects to the surgical staple cartridge  304  ( FIG.  15   ). Several parts of the end effector  300  are omitted to enable a clearer understanding of the present disclosure. In certain instances, the end effector  300  may include a first jaw such as, for example, the anvil  306  ( FIG.  20   ) and a second jaw such as, for example, the elongated channel  198  ( FIG.  14   ). In certain instances, as described above, the elongated channel  198  may accommodate a staple cartridge such as, for example, the surgical staple cartridge  304  or the staple cartridge  1100 , for example. At least one of the elongated channel  198  and the anvil  306  may be movable relative to the other one of the elongated channel  198  and the anvil  306  to capture tissue between the staple cartridge  1100  and the anvil  306 . Various actuation assemblies are described herein to facilitation motion of the elongated channel  198  and/or the anvil  306  between an open configuration ( FIG.  1   ) and a closed configuration ( FIG.  77   ), for example. 
     In certain instances, as described above, the E-beam  178  can be advanced distally to deploy the staples  191  into the captured tissue and/or advance the cutting edge  182  between a plurality of positions to engage and cut the captured tissue. As illustrated in  FIG.  76   , the cutting edge  182  can be advanced distally along a path defined by the slot  193 , for example. In certain instances, the cutting edge  182  can be advanced from a proximal portion  1103  of the staple cartridge  1100  to a distal portion  1105  of the staple cartridge  1100  to cut the captured tissue. In certain instances, the cutting edge  182  can be retracted proximally from the distal portion  1105  to the proximal portion  1103  by retraction of the E-beam  178  proximally, for example. 
     In certain instances, the cutting edge  182  can be employed to cut tissue captured by the end effector  300  in multiple procedures. The reader will appreciate that repetitive use of the cutting edge  182  may affect the sharpness of the cutting edge  182 . The reader will also appreciate that as the sharpness of the cutting edge  182  decreases, the force required to cut the captured tissue with the cutting edge  182  may increase. Referring to  FIGS.  78 - 83   , in certain instances, the surgical instrument  10  may comprise a circuit  1106  ( FIG.  78   ) for monitoring the sharpness of the cutting edge  182  during, before, and/or after operation of the surgical instrument  10  in a surgical procedure, for example. In certain instances, the circuit  1106  can be employed to test the sharpness of the cutting edge  182  prior to utilizing the cutting edge  182  to cut the captured tissue. In certain instances, the circuit  1106  can be employed to test the sharpness of the cutting edge  182  after the cutting edge  182  has been used to cut the captured tissue. In certain instances, the circuit  1106  can be employed to test the sharpness of the cutting edge  182  prior to and after the cutting edge  182  is used to cut the captured tissue. In certain instances, the circuit  1106  can be employed to test the sharpness of the cutting edge  182  at the proximal portion  1103  and/or at the distal portion  1105 . 
     Referring to  FIGS.  78 - 83   , the circuit  1106  may include one or more sensors such as, for example, an optical sensor  1108 ; the optical sensor  1108  of the circuit  1106  can be employed to test the reflective ability of the cutting edge  182 , for example. In certain instances, the ability of the cutting edge  182  to reflect light may correlate with the sharpness of the cutting edge  182 . In other words, a decrease in the sharpness of the cutting edge  182  may result in a decrease in the ability of the cutting edge  182  to reflect the light. Accordingly, in certain instances, the dullness of the cutting edge  182  can be evaluated by monitoring the intensity of the light reflected from the cutting edge  182 , for example. In certain instances, the optical sensor  1108  may define a light sensing region. The optical sensor  1108  can be oriented such that the optical sensing region is disposed in the path of the cutting edge  182 , for example. The optical sensor  1108  may be employed to sense the light reflected from the cutting edge  182  while the cutting edge  182  is in the optical sensing region, for example. A decrease in intensity of the reflected light beyond a threshold can indicate that the sharpness of the cutting edge  182  has decreased beyond an acceptable level. 
     Referring again to  FIGS.  78 - 83   , the circuit  1106  may include one or more lights sources such as, for example, a light source  1110 . In certain instances, the circuit  1106  may include a controller  1112  (“microcontroller”) which may be operably coupled to the optical sensor  1108 , as illustrated in  FIGS.  78 - 83   . In certain instances, the controller  1112  may include a processor  1114  (“microprocessor”) and one or more computer readable mediums or memory  1116  (“memory units”). In certain instances, the memory  1116  may store various program instructions, which when executed may cause the processor  1114  to perform a plurality of functions and/or calculations described herein. In certain instances, the memory  1116  may be coupled to the processor  1114 , for example. A power source  1118  can be configured to supply power to the controller  1112 , the optical sensors  1108 , and/or the light sources  1110 , for example. In certain instances, the power source  1118  may comprise a battery (or “battery pack” or “power pack”), such as a Li ion battery, for example. In certain instances, the battery pack may be configured to be releasably mounted to the handle assembly  14  for supplying power to the surgical instrument  10 . A number of battery cells connected in series may be used as the power source  4428 . In certain instances, the power source  1118  may be replaceable and/or rechargeable, for example. 
     The controller  1112  and/or other controllers of the present disclosure may be implemented using integrated and/or discrete hardware elements, software elements, and/or a combination of both. Examples of integrated hardware elements may include processors, microprocessors, controllers, integrated circuits, ASICs, PLDs, DSPs, FPGAs, logic gates, registers, semiconductor devices, chips, microchips, chip sets, controllers, SoC, and/or SIP. Examples of discrete hardware elements may include circuits and/or circuit elements such as logic gates, field effect transistors, bipolar transistors, resistors, capacitors, inductors, and/or relays. In certain instances, the controller  1112  may include a hybrid circuit comprising discrete and integrated circuit elements or components on one or more substrates, for example. In certain instances, the controller  1112  and/or other controllers of the present disclosure may be a single core or multicore controller LM4F230H5QR as described in connection with  FIGS.  14 - 17 B . 
     In certain instances, the light source  1110  can be employed to emit light which can be directed at the cutting edge  182  in the optical sensing region, for example. The optical sensor  1108  may be employed to measure the intensity of the light reflected from the cutting edge  182  while in the optical sensing region in response to exposure to the light emitted by the light source  1110 . In certain instances, the processor  1114  may receive one or more values of the measured intensity of the reflected light and may store the one or more values of the measured intensity of the reflected light on the memory  1116 , for example. The stored values can be detected and/or recorded before, after, and/or during a plurality of surgical procedures performed by the surgical instrument  10 , for example. 
     In certain instances, the processor  1114  may compare the measured intensity of the reflected light to a predefined threshold values that may be stored on the memory  1116 , for example. In certain instances, the controller  1112  may conclude that the sharpness of the cutting edge  182  has dropped below an acceptable level if the measured light intensity exceeds the predefined threshold value by 1%, 5%, 10%, 25%, 50%, 100% and/or more than 100%, for example. In certain instances, the processor  1114  can be employed to detect a decreasing trend in the stored values of the measured intensity of the light reflected from the cutting edge  182  while in the optical sensing region. 
     In certain instances, the surgical instrument  10  may include one or more feedback systems such as, for example, the feedback system  1120 . In certain instances, the processor  1114  can employ the feedback system  1120  to alert a user if the measured light intensity of the light reflected from cutting edge  182  while in the optical sensing region is beyond the stored threshold value, for example. In certain instances, the feedback system  1120  may comprise one or more visual feedback systems such as display screens, backlights, and/or LEDs, for example. In certain instances, the feedback system  1120  may comprise one or more audio feedback systems such as speakers and/or buzzers, for example. In certain instances, the feedback system  1120  may comprise one or more haptic feedback systems, for example. In certain instances, the feedback system  1120  may comprise combinations of visual, audio, and/or tactile feedback systems, for example. 
     In certain instances, the surgical instrument  10  may comprise a firing lockout mechanism  1122  which can be employed to prevent advancement of the cutting edge  182 . Various suitable firing lockout mechanisms are described in greater detail in U.S. Patent Application Publication No. 2014/0001231, entitled FIRING SYSTEM LOCKOUT ARRANGEMENTS FOR SURGICAL INSTRUMENTS, which is herein incorporated by reference in its entirety. In certain instances, as illustrated in  FIG.  78   , the processor  1114  can be operably coupled to the firing lockout mechanism  1122 ; the processor  1114  may employ the firing lockout mechanism  1122  to prevent advancement of the cutting edge  182  in the event it is determined that the measured intensity of the light reflected from the cutting edge  182  is beyond the stored threshold, for example. In other words, the processor  1114  may activate the firing lockout mechanism  1122  if the cutting edge is not sufficiently sharp to cut the tissue captured by the end effector  300 . 
     In certain instances, the optical sensor  1108  and the light source  1110  can be housed at a distal portion of the interchangeable shaft assembly  200 . In certain instances, the sharpness of cutting edge  182  can be evaluated by the optical sensor  1108 , as described above, prior to transitioning the cutting edge  182  into the end effector  300 . The firing bar  172  ( FIG.  14   ) may advance the cutting edge  182  through the optical sensing region defined by the optical sensor  1108  while the cutting edge  182  is in the interchangeable shaft assembly  200  and prior to entering the end effector  300 , for example. In certain instances, the sharpness of cutting edge  182  can be evaluated by the optical sensor  1108  after retracting the cutting edge  182  proximally from the end effector  300 . The firing bar  172  ( FIG.  14   ) may retract the cutting edge  182  through the optical sensing region defined by the optical sensor  1108  after retracting the cutting edge  182  from the end effector  300  into the interchangeable shaft assembly  200 , for example. 
     In certain instances, the optical sensor  1108  and the light source  1110  can be housed at a proximal portion of the end effector  300  which can be proximal to the staple cartridge  1100 , for example. The sharpness of cutting edge  182  can be evaluated by the optical sensor  1108  after transitioning the cutting edge  182  into the end effector  300  but prior to engaging the staple cartridge  1100 , for example. In certain instances, the firing bar  172  ( FIG.  14   ) may advance the cutting edge  182  through the optical sensing region defined by the optical sensor  1108  while the cutting edge  182  is in the end effector  300  but prior to engaging the staple cartridge  1100 , for example. 
     In various instances, the sharpness of cutting edge  182  can be evaluated by the optical sensor  1108  as the cutting edge  182  is advanced by the firing bar  172  through the slot  193 . As illustrated in  FIGS.  78 - 83   , the optical sensor  1108  and the light source  1110  can be housed at the proximal portion  1103  of the staple cartridge  1100 , for example; and the sharpness of cutting edge  182  can be evaluated by the optical sensor  1108  at the proximal portion  1103 , for example. The firing bar  172  ( FIG.  14   ) may advance the cutting edge  182  through the optical sensing region defined by the optical sensor  1108  at the proximal portion  1103  before the cutting edge  182  engages tissue captured between the staple cartridge  1100  and the anvil  306 , for example. In certain instances, as illustrated in  FIGS.  78 - 83   , the optical sensor  1108  and the light source  1110  can be housed at the distal portion  1105  of the staple cartridge  1100 , for example. The sharpness of cutting edge  182  can be evaluated by the optical sensor  1108  at the distal portion  1105 . In certain instances, the firing bar  172  ( FIG.  14   ) may advance the cutting edge  182  through the optical sensing region defined by the optical sensor  1108  at the distal portion  1105  after the cutting edge  182  has passed through the tissue captured between the staple cartridge  1100  and the anvil  306 , for example. 
     Referring again to  FIG.  76   , the staple cartridge  1100  may comprise a plurality of optical sensors  1108  and a plurality of corresponding light sources  1110 , for example. In certain instances, a pair of the optical sensor  1108  and the light source  1110  can be housed at the proximal portion  1103  of the staple cartridge  1100 , for example; and a pair of the optical sensor  1108  and the light source  1110  can be housed at the distal portion  1105  of the staple cartridge  1100 , for example. In such instances, the sharpness of the cutting edge  182  can be evaluated a first time at the proximal portion  1103  prior to engaging the tissue, for example, and a second time at the distal portion  1105  after passing through the captured tissue, for example. 
     The reader will appreciate that an optical sensor  1108  may evaluate the sharpness of the cutting edge  182  a plurality of times during a surgical procedure. For example, the sharpness of the cutting edge can be evaluated a first time during advancement of the cutting edge  182  through the slot  193  in a firing stroke, and a second time during retraction of the cutting edge  182  through the slot  193  in a return stroke, for example. In other words, the light reflected from the cutting edge  182  can be measured by the optical sensor  1108  once as the cutting edge is advanced through the optical sensing region, and once as the cutting edge  182  is retracted through the optical sensing region, for example. 
     The reader will appreciate that the processor  1114  may receive a plurality of readings of the intensity of the light reflected from the cutting edge  182  from one or more of the optical sensors  1108 . In certain instances, the processor  1114  may be configured to discard outliers and calculate an average reading from the plurality of readings, for example. In certain instances, the average reading can be compared to a threshold stored in the memory  1116 , for example. In certain instances, the processor  1114  may be configured to alert a user through the feedback system  1120  and/or activate the firing lockout mechanism  1122  if it is determined that the calculated average reading is beyond the threshold stored in the memory  1116 , for example. 
     In certain instances, as illustrated in  FIGS.  77 ,  79 , and  80   , a pair of the optical sensor  1108  and the light source  1110  can be positioned on opposite sides of the staple cartridge  1100 . In other words, the optical sensor  1108  can be positioned on a first side  1124  of the slot  193 , for example, and the light source  1110  can be positioned on a second side  1126 , opposite the first side  1124 , of the slot  193 , for example. In certain instances, the pair of the optical sensor  1108  and the light source  1110  can be substantially disposed in a plane transecting the staple cartridge  1100 , as illustrated in  FIG.  77   . The pair of the optical sensor  1108  and the light source  1110  can be oriented to define an optical sensing region that is positioned, or at least substantially positioned, on the plane transecting the staple cartridge  1100 , for example. Alternatively, the pair of the optical sensor  1108  and the light source  1110  can be oriented to define an optical sensing region that is positioned proximal to the plane transecting the staple cartridge  1100 , for example, as illustrated in  FIG.  80   . 
     In certain instances, a pair of the optical sensor  1108  and the light source  1110  can be positioned on a same side of the staple cartridge  1100 . In other words, as illustrated in  FIG.  81   , the pair of the optical sensor  1108  and the light source  1110  can be positioned on a first side of the cutting edge  182 , e.g. the side  1128 , as the cutting edge  182  is advanced through the slot  193 . In such instances, the light source  1110  can be oriented to direct light at the side  1128  of the cutting edge  182 ; and the intensity of the light reflected from the side  1128 , as measured by the optical sensor  1108 , may represent the sharpness of the side  1128 . 
     In certain instances, as illustrated in  FIG.  82   , a second pair of the optical sensor  1108  and the light source  1110  can be positioned on a second side of the cutting edge  182 , e.g. the side  1130 , for example. The second pair can be employed to evaluate the sharpness of the side  1130 . For example, the light source  1110  of the second pair can be oriented to direct light at the side  1130  of the cutting edge  182 ; and the intensity of the light reflected from the side  1130 , as measured by the optical sensor  1108  of the second pair, may represent the sharpness of the side  1130 . In certain instances, the processor can be configured to assess the sharpness of the cutting edge  182  based upon the measured intensities of the light reflected from the sides  1128  and  1130  of the cutting edge  182 , for example. 
     In certain instances, as illustrated in  FIG.  77   , a pair of the optical sensor  1108  and the light source  1110  can be housed at the distal portion  1105  of the staple cartridge  1100 . As illustrated in  FIG.  81   , the optical sensor  1108  can be positioned, or at least substantially positioned, on an axis LL which extends longitudinally along the path of the cutting edge  182  through the slot  193 , for example. In addition, the light source  1110  can be positioned distal to the cutting edge  182  and oriented to direct light at the cutting edge  182  as the cutting edge is advanced toward the light source  1110 , for example. Furthermore, the optical sensor  1108  can be positioned, or at least substantially positioned, along an axis AA that intersects the axis LL, as illustrated in  FIG.  81   . In certain instances, the axis AA may be perpendicular to the axis LL, for example. In any event, the optical sensor  1108  can be oriented to define an optical sensing region at the intersection of the axis LL and the axis AA, for example. 
     The reader will appreciate that the position, orientation and/or number of optical sensors and corresponding light sources described herein in connection with the surgical instrument  10  are example aspects intended for illustration purposes. Various other arrangements of optical sensors and light sources can be employed by the present disclosure to evaluate the sharpness of the cutting edge  182 . 
     The reader will appreciate that advancement of the cutting edge  182  through the tissue captured by the end effector  300  may cause the cutting edge to collect tissue debris and/or bodily fluids during each firing of the surgical instrument  10 . Such debris may interfere with the ability of the circuit  1106  to accurately evaluate the sharpness of the cutting edge  182 . In certain instances, the surgical instrument  10  can be equipped with one or more cleaning mechanisms which can be employed to clean the cutting edge  182  prior to evaluating the sharpness of the cutting edge  182 , for example. 
     Referring to  FIG.  76   , in certain instances, the staple cartridge  1100  may include a first pair of the optical sensor  1108  and the light source  1110 , which can be housed in the proximal portion  1103  of the staple cartridge  1100 , for example. Furthermore, as illustrated in  FIG.  76   , the staple cartridge  1100  may include a first pair of the cleaning members  1132 , which can be housed in the proximal portion  1103  on opposite sides of the slot  193 . The first pair of the cleaning members  1132  can be positioned distal to the first pair of the optical sensor  1108  and the light source  1110 , for example. As illustrated in  FIG.  76   , the staple cartridge  1100  may include a second pair of the optical sensor  1108  and the light source  1110 , which can be housed in the distal portion  1105  of the staple cartridge  1100 , for example. As illustrated in  FIG.  76   , the staple cartridge  1100  may include a second pair of the cleaning members  1132 , which can be housed in the distal portion  1105  on opposite sides of the slot  193 . The second pair of the cleaning members  1132  can be positioned proximal to the second pair of the optical sensor  1108  and the light source  1110 . 
     Further to the above, as illustrated in  FIG.  76   , the cutting edge  182  may be advanced distally in a firing stroke to cut tissue captured by the end effector  300 . As the cutting edge is advanced, a first evaluation of the sharpness of the cutting edge  182  can be performed by the first pair of the optical sensor  1108  and the light source  1110  prior to tissue engagement by the cutting edge  182 , for example. A second evaluation of the sharpness of the cutting edge  182  can be performed by the second pair of the optical sensor  1108  and the light source  1110  after the cutting edge  182  has transected the captured tissue, for example. The cutting edge  182  may be advanced through the second pair of the cleaning members  1132  prior to the second evaluation of the sharpness of the cutting edge  182  to remove any debris collected by the cutting edge  182  during the transection of the captured tissue. 
     Further to the above, as illustrated in  FIG.  76   , the cutting edge  182  may be retracted proximally in a return stroke. As the cutting edge is retracted, a third evaluation of the sharpness of the cutting edge  182  can be performed by the first pair of the optical sensor  1108  and the light source  1110  during the return stroke. The cutting edge  182  may be retracted through the first pair of the cleaning members  1132  prior to the third evaluation of the sharpness of the cutting edge  182  to remove any debris collected by the cutting edge  182  during the transection of the captured tissue, for example. 
     In certain instances, one or more of the lights sources  1110  may comprise one or more optical fiber cables. In certain instances, one or more flex circuits  1134  can be employed to transmit energy from the power source  1118  to the optical sensors  1108  and/or the light sources  1110 . In certain instances, the flex circuits  1134  may be configured to transmit one or more of the readings of the optical sensors  1108  to the controller  1112 , for example. 
     Referring now to  FIG.  84   , a staple cartridge  4300  is depicted; the staple cartridge  4300  is similar in many respects to the surgical staple cartridge  304  ( FIG.  14   ). For example, the staple cartridge  4300  can be employed with the end effector  300 . In certain instances, as illustrated in  FIG.  84   , the staple cartridge  4300  may comprise a sharpness testing member  4302  which can be employed to test the sharpness of the cutting edge  182 . In certain instances, the sharpness testing member  4302  can be attached to and/or integrated with the cartridge body  194  of the staple cartridge  4300 , for example. In certain instances, the sharpness testing member  4302  can be disposed in the proximal portion  1103  of the staple cartridge  4300 , for example. In certain instances, as illustrated in  FIG.  84   , the sharpness testing member  4302  can be disposed onto a cartridge deck  4304  of the staple cartridge  4300 , for example. 
     In certain instances, as illustrated in  FIG.  84   , the sharpness testing member  4302  can extend across the slot  193  of the staple cartridge  4300  to bridge, or at least partially bridge, the gap defined by the slot  193 , for example. In certain instances, the sharpness testing member  4302  may interrupt, or at least partially interrupt, the path of the cutting edge  182 . The cutting edge  182  may engage, cut, and/or pass through the sharpness testing member  4302  as the cutting edge  182  is advanced during a firing stroke, for example. In certain instances, the cutting edge  182  may be configured to engage, cut, and/or pass through the sharpness testing member  4302  prior to engaging tissue captured by the end effector  300  in a firing stroke, for example. In certain instances, the cutting edge  182  may be configured to engage the sharpness testing member  4302  at a proximal end  4306  of the sharpness testing member  4302 , and exit and/or disengage the sharpness testing member  4302  at a distal end  4308  of the sharpness testing member  4302 , for example. In certain instances, the cutting edge  182  can travel and/or cut through the sharpness testing member  4302  a distance (D) between the proximal end  4306  and the distal end  4308 , for example, as the cutting edge  182  is advanced during a firing stroke. 
     Referring primarily to  FIGS.  84  and  85   , the surgical instrument  10  may comprise a circuit  4310  for testing the sharpness of the cutting edge  182 , for example. In certain instances, the circuit  4310  can evaluate the sharpness of the cutting edge  182  by testing the ability of the cutting edge  182  to be advanced through the sharpness testing member  4302 . For example, the circuit  4310  can be configured to observe the time period the cutting edge  182  takes to fully transect and/or completely pass through at least a predetermined portion of the sharpness testing member  4302 . If the observed time period exceeds a predetermined threshold, the circuit  4310  may conclude that the sharpness of the cutting edge  182  has dropped below an acceptable level, for example. 
     In certain instances, the circuit  4310  may include a controller  4312  (“microcontroller”) which may include a processor  4314  (“microprocessor”) and one or more computer readable mediums or memory  4316  units (“memory”). In certain instances, the memory  4316  may store various program instructions, which when executed may cause the processor  4314  to perform a plurality of functions and/or calculations described herein. In certain instances, the memory  4316  may be coupled to the processor  4314 , for example. A power source  4318  can be configured to supply power to the controller  4312 , for example. In certain instances, the power source  4138  may comprise a battery (or “battery pack” or “power pack”), such as a Li ion battery, for example. In certain instances, the battery pack may be configured to be releasably mounted to the handle assembly  14 . A number of battery cells connected in series may be used as the power source  4318 . In certain instances, the power source  4318  may be replaceable and/or rechargeable, for example. 
     In certain instances, the controller  4313  can be operably coupled to the feedback system  1120  and/or the firing lockout mechanism  1122 , for example. 
     Referring to  FIGS.  84  and  85   , the circuit  4310  may comprise one or more position sensors. Example position sensors and positioning systems suitable for use with the present disclosure are described in U.S. Patent Application Publication No. 2014/0263538, entitled SENSOR ARRANGEMENTS FOR ABSOLUTE POSITIONING SYSTEM FOR SURGICAL INSTRUMENTS, which is herein incorporated by reference in its entirety. In certain instances, the circuit  4310  may include a first position sensor  4320  and a second position sensor  4322 . In certain instances, the first position sensor  4320  can be employed to detect a first position of the cutting edge  182  at the proximal end  4306  of the sharpness testing member  4302 , for example; and the second position sensor  4322  can be employed to detect a second position of the cutting edge  182  at the distal end  4308  of the sharpness testing member  4302 , for example. 
     In certain instances, the first and second position sensors  4320 ,  4322  can be employed to provide first and second position signals, respectively, to the controller  4312 . It will be appreciated that the position signals may be analog signals or digital values based on the interface between the controller  4312  and the first and second position sensors  4320 ,  4322 . In one aspect, the interface between the controller  4312  and the first and second position sensors  4320 ,  4322  can be a standard serial peripheral interface (SPI), and the position signals can be digital values representing the first and second positions of the cutting edge  182 , as described above. 
     Further to the above, the processor  4314  may determine the time period between receiving the first position signal and receiving the second position signal. The determined time period may correspond to the time it takes the cutting edge  182  to advance through the sharpness testing member  4302  from the first position at the proximal end  4306  of the sharpness testing member  4302 , for example, to the second position at the distal end  4308  of the sharpness testing member  4302 , for example. In at least one example, the controller  4312  may include a time element which can be activated by the processor  4314  upon receipt of the first position signal, and deactivated upon receipt of the second position signal. The time period between the activation and deactivation of the time element may correspond to the time it takes the cutting edge  182  to advance from the first position to the second position, for example. The time element may comprise a real time clock, a processor configured to implement a time function, or any other suitable timing circuit. 
     In various instances, the controller  4312  can compare the time period it takes the cutting edge  182  to advance from the first position to the second position to a predefined threshold value to assess whether the sharpness of the cutting edge  182  has dropped below an acceptable level, for example. In certain instances, the controller  4312  may conclude that the sharpness of the cutting edge  182  has dropped below an acceptable level if the measured time period exceeds the predefined threshold value by 1%, 5%, 10%, 25%, 50%, 100% and/or more than 100%, for example. 
     Referring to  FIG.  86   , in various instances, an electric motor  4330  can drive the firing bar  172  ( FIG.  14   ) to advance the cutting edge  182  during a firing stroke and/or to retract the cutting edge  182  during a return stroke, for example. A motor driver  4332  can control the electric motor  4330 ; and a controller such as, for example, the controller  4312  can be in signal communication with the motor driver  4332 . As the electric motor  4330  advances the cutting edge  182 , the controller  4312  can determine the current drawn by the electric motor  4330 , for example. In such instances, the force required to advance the cutting edge  182  can correspond to the current drawn by the electric motor  4330 , for example. Referring still to  FIG.  86   , the controller  4312  of the surgical instrument  10  can determine if the current drawn by the electric motor  4330  increases during advancement of the cutting edge  182  and, if so, can calculate the percentage increase of the current. 
     In certain instances, the current drawn by the electric motor  4330  may increase significantly while the cutting edge  182  is in contact with the sharpness testing member  4302  due to the resistance of the sharpness testing member  4302  to the cutting edge  182 . For example, the current drawn by the electric motor  4330  may increase significantly as the cutting edge  182  engages, passes and/or cuts through the sharpness testing member  4302 . The reader will appreciate that the resistance of the sharpness testing member  4302  to the cutting edge  182  depends, in part, on the sharpness of the cutting edge  182 ; and as the sharpness of the cutting edge  182  decreases from repetitive use, the resistance of the sharpness testing member  4302  to the cutting edge  182  will increase. Accordingly, the value of the percentage increase of the current drawn by the electric motor  4330  while the cutting edge is in contact with the sharpness testing member  4302  can increase as the sharpness of the cutting edge  182  decreases from repetitive use, for example. 
     In certain instances, the determined value of the percentage increase of the current drawn by the electric motor  4330  can be the maximum detected percentage increase of the current drawn by the electric motor  4330 . In various instances, the controller  4312  can compare the determined value of the percentage increase of the current drawn by the electric motor  4330  to a predefined threshold value of the percentage increase of the current drawn by the electric motor  4330 . If the determined value exceeds the predefined threshold value, the controller  4312  may conclude that the sharpness of the cutting edge  182  has dropped below an acceptable level, for example. 
     In certain instances, as illustrated in  FIG.  86   , the processor  4314  can be in communication with the feedback system  1120  and/or the firing lockout mechanism  1122 , for example. In certain instances, the processor  4314  can employ the feedback system  1120  to alert a user if the determined value of the percentage increase of the current drawn by the electric motor  4330  exceeds the predefined threshold value, for example. In certain instances, the processor  4314  may employ the firing lockout mechanism  1122  to prevent advancement of the cutting edge  182  if the determined value of the percentage increase of the current drawn by the electric motor  4330  exceeds the predefined threshold value, for example. 
     In various instances, the controller  4312  can utilize an algorithm to determine the change in current drawn by the electric motor  4330 . For example, a current sensor can detect the current drawn by the electric motor  4330  during the firing stroke. The current sensor can continually detect the current drawn by the electric motor and/or can intermittently detect the current draw by the electric motor. In various instances, the algorithm can compare the most recent current reading to the immediately proceeding current reading, for example. Additionally or alternatively, the algorithm can compare a sample reading within a time period X to a previous current reading. For example, the algorithm can compare the sample reading to a previous sample reading within a previous time period X, such as the immediately proceeding time period X, for example. In other instances, the algorithm can calculate the trending average of current drawn by the motor. The algorithm can calculate the average current draw during a time period X that includes the most recent current reading, for example, and can compare that average current draw to the average current draw during an immediately proceeding time period time X, for example. 
     Referring to  FIG.  87   , a method  4500  is depicted for evaluating the sharpness of the cutting edge  182  of the surgical instrument  10 ; and various responses are outlined in the event the sharpness of the cutting edge  182  drops to and/or below an alert threshold and/or a high severity threshold, for example. In various instances, a controller such as, for example, the controller  4312  can be configured to implement the method depicted in  FIG.  85   . In certain instances, the surgical instrument  10  may include a load cell  4334  ( FIG.  86   ); as illustrated in  FIG.  84   , the controller  4312  may be in communication with the load cell  4334 . In certain instances, the load cell  4334  may include a force sensor such as, for example, a strain gauge, which can be operably coupled to the firing bar  172 , for example. In certain instances, the controller  4312  may employ the load cell  4334  to monitor the force (Fx) applied to the cutting edge  182  as the cutting edge  182  is advanced during a firing stroke. 
     Accordingly, when the knife firing is initiated  4502  the system checks  4504  the dullness of the cutting edge  182  of the knife by sensing a force Fx. The sensed force Fx is compared to a threshold force F 1  and determines  4506  whether the sensed force Fx is greater than the threshold force F 1 . When the sensed force Fx is less than or equal to the threshold force F 1 , the process proceeds along NO branch and displays  4508  nothing and continues  4510  the knife firing process. When the sensed force Fx is greater than the threshold force F 1 , the process proceeds along YES branch and determines  4512  whether the sensed force Fx exceeds a high severity threshold force F 2 . When the sensed force Fx is less than or equal to the threshold F 2 , the process proceeds along NO branch and notifies  4514  the processor that the cutting edge  182  of the knife is dulling and the continues  4510  the knife firing process. When the sensed force Fx is greater than the threshold F 2 , the process proceeds along YES branch and notifies  4516  the processor that the cutting edge  182  of the knife is dulled and the knife firing lockout is engaged. Subsequently, optionally, the processor may override  4518  the knife firing lockout and continues  4510  the knife firing process if the lockout is overridden. 
     Referring to  FIG.  88   , a method  4600  is depicted for determining whether a cutting edge such as, for example, the cutting edge  182  is sufficiently sharp to be employed in transecting a tissue of a particular tissue thickness that is captured by the end effector  300 , for example. As described above, repetitive use of the cutting edge  182  may dull or reduce the sharpness of the cutting edge  182  which may increase the force required for the cutting edge  182  to transect the captured tissue. In other words, the sharpness level of the cutting edge  182  can be defined by the force required for the cutting edge  182  to transect the captured tissue, for example. The reader will appreciate that the force required for the cutting edge  182  to transect a captured tissue may also depend on the thickness of the captured tissue. In certain instances, the greater the thickness of the captured tissue, the greater the force required for the cutting edge  182  to transect the captured tissue at the same sharpness level, for example. 
     Accordingly, initially, the stapler clamps  4602  the tissue between the anvil and the jaw member. The system senses  4604  the tissue thickness Tx and initiates  4606  the knife firing process. Upon initiating the knife firing process, the system senses  4608  the load resistance from the clamped tissue and compares the sensed force Fx and senses thickness Tx against various thresholds and determines  4610  several outcomes based on the evaluation. In one aspect, when the process determines  4610  whether the sensed tissue thickness Tx is within a first tissue thickness range defined between a first tissue thickness threshold T 1  and a second tissue thickness threshold T 2  AND the sensed force Fx is greater than a first force threshold F 1  AND the process determines  4610  whether the sensed tissue thickness Tx is within a second tissue thickness range defined between the second tissue thickness threshold T 2  and a third tissue thickness threshold T 3  AND the sensed force Fx is greater than a second force threshold F 2 , the process proceeds along the YES branch and notifies  4612  or alerts the processor that the knife is dulling and then continues  4614  the knife firing process. Otherwise, the process proceeds along the NO branch and the does not notify  4616  the processor and continues the knife firing process. Generally, the process determines whether the sensed tissue thickness Tx is within a tissue thickness range defined between tissue thickness thresholds Tn and Tn+1 AND the sensed force Fx is greater than a force threshold Tn, where n indicates a tissue thickness range. When the process determines  4610  that the sensed tissue thickness Tx is within a first tissue thickness range defined between a first tissue thickness threshold T 1  and a second tissue thickness threshold T 2  AND the sensed force Fx is greater than a first force threshold F 1  AND when the process determines  4610  that the sensed tissue thickness Tx is within a second tissue thickness range defined between the second tissue thickness threshold T 2  and a third tissue thickness threshold T 3  AND the sensed force Fx is greater than a second force threshold F 2 , the process continues. 
     In certain instances, the cutting edge  182  may be sufficiently sharp for transecting a captured tissue comprising a first thickness but may not be sufficiently sharp for transecting a captured tissue comprising a second thickness greater than the first thickness, for example. In certain instances, a sharpness level of the cutting edge  182 , as defined by the force required for the cutting edge  182  to transect a captured tissue, may be adequate for transecting the captured tissue if the captured tissue comprises a tissue thickness that is in a particular range of tissue thicknesses, for example. 
     In certain instances, as illustrated in  FIG.  89   , the memory  4316  can store one or more predefined ranges of tissue thicknesses of tissue captured by the end effector  300 ; and predefined threshold forces associated with the predefined ranges of tissue thicknesses. In certain instances, each predefined threshold force may represent a minimum sharpness level of the cutting edge  182  that is suitable for transecting a captured tissue comprising a tissue thickness (Tx) encompassed by the range of tissue thicknesses that is associated with the predefined threshold force. In certain instances, if the force (Fx) required for the cutting edge  182  to transect the captured tissue, comprising the tissue thickness (Tx), exceeds the predefined threshold force associated with the predefined range of tissue thicknesses that encompasses the tissue thickness (Tx), the cutting edge  182  may not be sufficiently sharp to transect the captured tissue, for example. 
     In certain instances, the predefined threshold forces and their corresponding predefined ranges of tissue thicknesses can be stored in a database and/or a table on the memory  4316  such as, for example, a table  4342 , as illustrated in  FIG.  89   . In certain instances, the processor  4314  can be configured to receive a measured value of the force (Fx) required for the cutting edge  182  to transect a captured tissue and a measured value of the tissue thickness (Tx) of the captured tissue. The processor  4314  may access the table  4342  to determine the predefined range of tissue thicknesses that encompasses the measured tissue thickness (Tx). In addition, the processor  4314  may compare the measured force (Fx) to the predefined threshold force associated with the predefined range of tissue thicknesses that encompasses the tissue thickness (Tx). In certain instances, if the measured force (Fx) exceeds the predefined threshold force, the processor  4314  may conclude that the cutting edge  182  may not be sufficiently sharp to transect the captured tissue, for example. 
     Further to the above, the processor  4314  ( FIGS.  85 ,  86   ) may employ one or more tissue thickness sensing modules such as, for example, a tissue thickness sensing module  4336  to determine the thickness of the captured tissue. Various suitable tissue thickness sensing modules are described in the present disclosure. In addition, various tissue thickness sensing devices and methods, which are suitable for use with the present disclosure, are disclosed in U.S. Patent Application Publication No. 2011/0155781, entitled SURGICAL CUTTING INSTRUMENT THAT ANALYZES TISSUE THICKNESS, which is herein incorporated by reference in its entirety. 
     In certain instances, the processor  4314  may employ the load cell  4334  to measure the force (Fx) required for the cutting edge  182  to transect a captured tissue comprising a tissue thickness (Tx). The reader will appreciate that that the force applied to the cutting edge  182  by the captured tissue, while the cutting edge  182  is engaged and/or in contact with the captured tissue, may increase as the cutting edge  182  is advanced against the captured tissue up to the force (Fx) at which the cutting edge  182  may transect the captured tissue. In certain instances, the processor  4314  may employ the load cell  4334  to continually monitor the force applied by the captured tissue against the cutting edge  182  as the cutting edge  182  is advanced against the captured tissue. The processor  4314  may continually compare the monitored force to the predefined threshold force associated with the predefined tissue thickness range encompassing the tissue thickness (Tx) of the captured tissue. In certain instances, if the monitored force exceeds the predefined threshold force, the processor  4314  may conclude that the cutting edge is not sufficiently sharp to safely transect the captured tissue, for example. 
     The method  4600  described in  FIG.  88    outline various example actions that can be taken by the controller  4313  in the event it is determined that the cutting edge  182  is not be sufficiently sharp to safely transect the captured tissue, for example. In certain instances, the controller  4312  may warn the user that the cutting edge  182  is too dull for safe use, for example, through the feedback system  1120 , for example. In certain instances, the controller  4312  may employ the firing lockout mechanism  1122  to prevent advancement of the cutting edge  182  upon concluding that the cutting edge  182  is not sufficiently sharp to safely transect the captured tissue, for example. In certain instances, the controller  4312  may employ the feedback system  1120  to provide instructions to the user for overriding the firing lockout mechanism  1122 , for example. 
       FIGS.  90 ,  91    illustrate various aspects of an apparatus, system, and method for employing a common controller with a plurality of motors in connection with a surgical instrument such as, for example, a motor-driven surgical instrument  4400 . The surgical instrument  4400  is similar in many respects to other surgical instruments described by the present disclosure such as, for example, the surgical instrument  10  of  FIG.  1    which is described in greater detail above. The surgical instrument  4400  includes the housing  12 , the handle assembly  14 , the closure trigger  32 , the interchangeable shaft assembly  200 , and the end effector  300 . Accordingly, for conciseness and clarity of disclosure, a detailed description of certain features of the surgical instrument  4400 , which are common with the surgical instrument  10 , will not be repeated here. 
     Referring still to  FIGS.  90 ,  91   , the surgical instrument  4400  may include a plurality of motors which can be activated to perform various functions in connection with the operation of the surgical instrument  4400 . In certain instances, a first motor can be activated to perform a first function; a second motor can be activated to perform a second function; and a third motor can be activated to perform a third function. In certain instances, the plurality of motors of the surgical instrument  4400  can be individually activated to cause articulation, closure, and/or firing motions in the end effector  300  ( FIGS.  1 ,  15   ). The articulation, closure, and/or firing motions can be transmitted to the end effector  300  through the interchangeable shaft assembly  200  ( FIG.  1   ), for example. 
     In certain instances, as illustrated in  FIG.  91   , the surgical instrument  4400  may include a firing motor  4402 . The firing motor  4402  may be operably coupled to a firing drive assembly  4404  which can be configured to transmit firing motions generated by the firing motor  4402  to the end effector  300  ( FIGS.  1 ,  14   ). In certain instances, the firing motions generated by the firing motor  4402  may cause the staples  191  to be deployed from the surgical staple cartridge  304  into tissue captured by the end effector  300  and/or the cutting edge  182  to be advanced to cut the captured tissue, for example. 
     In certain instances, as illustrated in  FIG.  91   , the surgical instrument  4400  may include an articulation motor  4406 , for example. The articulation motor  4406  may be operably coupled to an articulation drive assembly  4408  which can be configured to transmit articulation motions generated by the articulation motor  4406  to the end effector  300  ( FIGS.  1 ,  14   ). In certain instances, the articulation motions may cause the end effector  300  to articulate relative to the interchangeable shaft assembly  200  ( FIG.  1   ), for example. In certain instances, the surgical instrument  4400  may include a closure motor, for example. The closure motor may be operably coupled to a closure drive assembly which can be configured to transmit closure motions to the end effector  300 . In certain instances, the closure motions may cause the end effector  300  to transition from an open configuration to an approximated configuration to capture tissue, for example. The reader will appreciate that the motors described herein and their corresponding drive assemblies are intended as examples of the types of motors and/or driving assemblies that can be employed in connection with the present disclosure. The surgical instrument  4400  may include various other motors which can be utilized to perform various other functions in connection with the operation of the surgical instrument  4400 . 
     As described above, the surgical instrument  4400  may include a plurality of motors which may be configured to perform various independent functions. In certain instances, the plurality of motors of the surgical instrument  4400  can be individually or separately activated to perform one or more functions while the other motors remain inactive. For example, the articulation motor  4406  can be activated to cause the end effector  300  ( FIGS.  1 ,  14   ) to be articulated while the firing motor  4402  remains inactive. Alternatively, the firing motor  4402  can be activated to fire the plurality of staples  191  ( FIG.  14   ) and/or advance the cutting edge  182  while the articulation motor  4406  remains inactive. 
     With reference to  FIGS.  90 ,  91   , in certain instances, the surgical instrument  4400  may include a common controller  4410  which can be employed with a plurality of motors  4402 ,  4406  of the surgical instrument  4400 . In certain instances, the common controller  4410  may accommodate one of the plurality of motors at a time. For example, the common controller  4410  can be separably couplable to the plurality of motors of the surgical instrument  4400  individually. In certain instances, a plurality of the motors of the surgical instrument  4400  may share one or more common controllers such as the common controller  4410 . In certain instances, a plurality of motors of the surgical instrument  4400  can be individually and selectively engaged the common controller  4410 . In certain instances, the common controller  4410  can be selectively switched from interfacing with one of a plurality of motors of the surgical instrument  4400  to interfacing with another one of the plurality of motors of the surgical instrument  4400 . 
     In at least one example, the common controller  4410  can be selectively switched between operable engagement with the articulation motor  4406  and operable engagement with the firing motor  4402 . In at least one example, as illustrated in  FIG.  90   , a switch  4414  can be moved or transitioned between a plurality of positions and/or states such as a first position  4416  and a second position  4418 , for example. In the first position  4416 , the switch  4414  may electrically couple the common controller  4410  to the articulation motor  4406 ; and in the second position  4418 , the switch  4414  may electrically couple the common controller  4410  to the firing motor  4402 , for example. In certain instances, the common controller  4410  can be electrically coupled to the articulation motor  4406 , while the switch  4414  is in the first position  4416 , to control the operation of the articulation motor  4406  to articulate the end effector  300  ( FIGS.  1 ,  15   ) to a desired position. In certain instances, the common controller  4410  can be electrically coupled to the firing motor  4402 , while the switch  4414  is in the second position  4418 , to control the operation of the firing motor  4402  to fire the plurality of staples  191  ( FIG.  14   ) and/or advance the cutting edge  182  ( FIG.  14   ), for example. In certain instances, the switch  4414  may be a mechanical switch, an electromechanical switch, a solid state switch, or any suitable switching mechanism. 
     Referring now to  FIG.  91   , an outer casing of the handle assembly  14  of the surgical instrument  4400  is removed and several features and elements of the surgical instrument  4400  are also removed for clarity of disclosure. In certain instances, as illustrated in  FIG.  91   , the surgical instrument  4400  may include an interface  4412  which can be selectively transitioned between a plurality of positions and/or states. In a first position and/or state, the interface  4412  may couple the common controller  4410  ( FIG.  90   ) to a first motor such as, for example, the articulation motor  4406 ; and in a second position and/or state, the interface  4412  may couple the common controller  4410  to a second motor such as, for example, the firing motor  4402 . Additional positions and/or states of the interface  4412  are contemplated by the present disclosure. 
     In certain instances, the interface  4412  is movable between a first position and a second position, wherein the common controller  4410  ( FIG.  90   ) is coupled to a first motor in the first position and a second motor in the second position. In certain instances, the common controller  4410  is decoupled from first motor as the interface  4412  is moved from the first position; and the common controller  4410  is decoupled from second motor as the interface  4412  is moved from the second position. In certain instances, a switch or a trigger can be configured to transition the interface  4412  between the plurality of positions and/or states. In certain instances, a trigger can be movable to simultaneously effectuate the end effector and transition the common controller  4410  from operable engagement with one of the motors of the surgical instrument  4400  to operable engagement with another one of the motors of the surgical instrument  4400 . 
     In at least one example, as illustrated in  FIG.  91   , the closure trigger  32  can be operably coupled to the interface  4412  and can be configured to transition the interface  4412  between a plurality of positions and/or states. As illustrated in  FIG.  91   , the closure trigger  32  can be movable, for example during a closure stroke, to transition the interface  4412  from a first position and/or state to a second position and/or state while transitioning the end effector  300  to an approximated configuration to capture tissue by the end effector, for example. 
     In certain instances, in the first position and/or state, the common controller  4410  can be electrically coupled to a first motor such as, for example, the articulation motor  4406 , and in the second position and/or state, the common controller  4410  can be electrically coupled to a second motor such as, for example, the firing motor  4402 . In the first position and/or state, the common controller  4410  may be engaged with the articulation motor  4406  to allow the user to articulate the end effector  300  ( FIGS.  1 ,  15   ) to a desired position; and the common controller  4410  may remain engaged with the articulation motor  4406  until the closure trigger  32  is actuated. As the user actuates the closure trigger  32  to capture tissue by the end effector  300  at the desired position, the interface  4412  can be transitioned or shifted to transition the common controller  4410  from operable engagement with the articulation motor  4406 , for example, to operable engagement with the firing motor  4402 , for example. Once operable engagement with the firing motor  4402  is established, the common controller  4410  may take control of the firing motor  4402 ; and the common controller  4410  may activate the firing motor  4402 , in response to user input, to fire the plurality of staples  191  ( FIG.  14   ) and/or advance the cutting edge  182  ( FIG.  14   ), for example. 
     In certain instances, as illustrated in  FIG.  91   , the common controller  4410  may include a plurality of electrical and/or mechanical contacts  4411  adapted for coupling engagement with the interface  4412 . The plurality of motors of the surgical instrument  4400 , which share the common controller  4410 , may each comprise one or more corresponding electrical and/or mechanical contacts  4413  adapted for coupling engagement with the interface  4412 , for example. 
     In various instances, the motors of the surgical instrument  4400  can be electrical motors. In certain instances, one or more of the motors of the surgical instrument  4400  can be a DC brushed driving motor having a maximum rotation of, approximately, 25,000 RPM, for example. In other arrangements, the motors of the surgical instrument  4400  may include one or more motors selected from a group of motors comprising a brushless motor, a cordless motor, a synchronous motor, a stepper motor, or any other suitable electric motor. 
     In various instances, as illustrated in  FIG.  90   , the common controller  4410  may comprise a motor driver  4426  which may comprise one or more H-Bridge field-effect transistors (FETs). The motor driver  4426  may modulate the power transmitted from a power source  4428  to a motor coupled to the common controller  4410  based on input from a controller  4420  (“microcontroller”), for example. In certain instances, the controller  4420  can be employed to determine the current drawn by the motor, for example, while the motor is coupled to the common controller  4410 , as described above. 
     In certain instances, the controller  4420  may include a processor  4422  (“microprocessor”) and one or more computer readable mediums or memory  4424  units (“memory”). In certain instances, the memory  4424  may store various program instructions, which when executed may cause the processor  4422  to perform a plurality of functions and/or calculations described herein. In certain instances, one or more of the memory  4424  may be coupled to the processor  4422 , for example. 
     In certain instances, the power source  4428  can be employed to supply power to the controller  4420 , for example. In certain instances, the power source  4428  may comprise a battery (or “battery pack” or “power pack”), such as a Li ion battery, for example. In certain instances, the battery pack may be configured to be releasably mounted to the handle assembly  14  for supplying power to the surgical instrument  4400 . A number of battery cells connected in series may be used as the power source  4428 . In certain instances, the power source  4428  may be replaceable and/or rechargeable, for example. 
     In various instances, the processor  4422  may control the motor driver  4426  to control the position, direction of rotation, and/or velocity of a motor that is coupled to the common controller  4410 . In certain instances, the processor  4422  can signal the motor driver  4426  to stop and/or disable a motor that is coupled to the common controller  4410 . It should be understood that the term processor as used herein includes any suitable processor, controller, or other basic computing device that incorporates the functions of a computer&#39;s central processing unit (CPU) on an integrated circuit or at most a few integrated circuits. The processor is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and provides results as output. It is an example of sequential digital logic, as it has internal memory. Processors operate on numbers and symbols represented in the binary numeral system. In one instance, the processor  4422  may be a single core or multicore controller LM4F230H5QR as described in connection with  FIGS.  15 - 17 B . 
     In certain instances, the memory  4424  may include program instructions for controlling each of the motors of the surgical instrument  4400  that are couplable to the common controller  4410 . For example, the memory  4424  may include program instructions for controlling the articulation motor  4406 . Such program instructions may cause the processor  4422  to control the articulation motor  4406  to articulate the end effector  300  in accordance with user input while the articulation motor  4406  is coupled to the common controller  4410 . In another example, the memory  4424  may include program instructions for controlling the firing motor  4402 . Such program instructions may cause the processor  4422  to control the firing motor  4402  to fire the plurality of staples  191  and/or advance the cutting edge  182  in accordance with user input while the firing motor  4402  is coupled to the common controller  4410 . 
     In certain instances, one or more mechanisms and/or sensors such as, for example, sensors  4430  can be employed to alert the processor  4422  to the program instructions that should be used in a particular setting. For example, the sensors  4430  may alert the processor  4422  to use the program instructions associated with articulation of the end effector  300  ( FIGS.  1 ,  14   ) while the common controller  4410  is coupled to the articulation motor  4406 ; and the sensors  4430  may alert the processor  4422  to use the program instructions associated with firing the surgical instrument  4400  while the common controller  4410  is coupled to the firing motor  4402 . In certain instances, the sensors  4430  may comprise position sensors which can be employed to sense the position of the switch  4414 , for example. Accordingly, the processor  4422  may use the program instructions associated with articulation of the end effector  300  upon detecting, through the sensors  4430  for example, that the switch  4414  is in the first position  4416 ; and the processor  4422  may use the program instructions associated with firing the surgical instrument  4400  upon detecting, through the sensors  4430  for example, that the switch  4414  is in the second position  4418 . 
     Referring now to  FIG.  92   , an outer casing of the surgical instrument  4400  is removed and several features and elements of the surgical instrument  4400  are also removed for clarity of disclosure. As illustrated in  FIG.  92   , the surgical instrument  4400  may include a plurality of sensors which can be employed to perform various functions in connection with the operation of the surgical instrument  4400 . For example, as illustrated in  FIG.  92   , the surgical instrument  4400  may include sensors A, B, and/or C. In certain instances, the sensor A can be employed to perform a first function, for example; the sensor B can be employed to perform a second function, for example; and the sensor C can be employed to perform a third function, for example. In certain instances, the sensor A can be employed to sense a thickness of the tissue captured by the end effector  300  ( FIGS.  1 ,  14   ) during a first segment of a closure stroke; the sensor B can be employed to sense the tissue thickness during a second segment of the closure stroke following the first segment; and the sensor C can be employed to sense the tissue thickness during a third segment of the closure stroke following the second segment, for example. In certain instances, the sensors A, B, and C can be disposed along the end effector  300 , for example. 
     In certain instances, the sensors A, B, and C can be arranged, as illustrated in  FIG.  94   , such that the sensor A is disposed proximal to the sensor B, and the sensor C is disposed proximal to the sensor B, for example. In certain instances, as illustrated in  FIG.  92   , the sensor A can sense the tissue thickness of the tissue captured by the end effector  300  at a first position; the sensor B can sense the tissue thickness of the tissue captured by the end effector  300  at a second position distal to the first position; and the sensor C can sense the tissue thickness of the tissue captured by the end effector  300  at a third position distal to the second position, for example. The reader will appreciate that the sensors described herein are intended as examples of the types of sensors which can be employed in connection with the present disclosure. Other suitable sensors and sensing arrangements can be employed by the present disclosure. 
     In certain instances, the surgical instrument  4400  may include a controller  4450  which can be similar in many respects to the common controller  4410 . For example, the controller  4450 , like the common controller  4410 , may comprise the controller  4420 , the processor  4422 , and/or the memory  4424 . In certain instances, the power source  4428  can supply power to the controller  4450 , for example. In certain instances, the surgical instrument  4400  may include a plurality of sensors such as the sensors A, B, and C, for example, which can activated to perform various functions in connection with the operation of the surgical instrument  4400 . In certain instances, one of the sensors A, B, and C, for example, can be individually or separately activated to perform one or more functions while the other sensors remain inactive. In certain instances, a plurality of sensors of the surgical instrument  4400  such as, for example, the sensors A, B, and C may share the controller  4450 . In certain instances, only one of the sensors A, B, and C can be coupled to the controller  4450  at a time. In certain instances, the plurality of sensors of the surgical instrument  4400  can be individually and separately couplable to the controller  4450 , for example. In at least one example, the controller  4450  can be selectively switched between operable engagement with sensor A, Sensor B, and/or Sensor C. 
     In certain instances, as illustrated in  FIG.  92   , the controller  4450  can be disposed in the handle assembly  14 , for example, and the sensors that share the controller  4450  can be disposed in the end effector  300  ( FIGS.  1 ,  14   ), for example. The reader will appreciate that the controller  4450  and/or the sensors that share the controller  4450  are not limited to the above identified positions. In certain instances, the controller  4450  and the sensors that share the controller  4450  can be disposed in the end effector  300 , for example. Other arrangements for the positions of the controller  4450  and/or the sensors that share the controller  4450  are contemplated by the present disclosure. 
     In certain instances, as illustrated in  FIG.  92   , an interface  4452  can be employed to manage the coupling and/or decoupling of the sensors of the surgical instrument  4400  to the controller  4450 . In certain instances, the interface  4452  can be selectively transitioned between a plurality of positions and/or states. In a first position and/or state, the interface  4452  may couple the controller  4450  to the sensor A, for example; in a second position and/or state, the interface  4452  may couple the controller  4450  to the sensor B, for example; and in a third position and/or state, the interface  4452  may couple the controller  4450  to the sensor C, for example. Additional positions and/or states of the interface  4452  are contemplated by the present disclosure. 
     In certain instances, the interface  4452  is movable between a first position, a second position, and/or a third position, for example, wherein the controller  4450  is coupled to a first sensor in the first position, a second sensor in the second position, and a third sensor in the third position. In certain instances, the controller  4450  is decoupled from first sensor as the interface  4452  is moved from the first position; the controller  4450  is decoupled from second sensor as the interface  4452  is moved from the second position; and the controller  4450  is decoupled from third sensor as the interface  4452  is moved from the third position. In certain instances, a switch or a trigger can be configured to transition the interface  4452  between the plurality of positions and/or states. In certain instances, a trigger can be movable to simultaneously effectuate the end effector and transition the controller  4450  from operable engagement with one of the sensors that share the controller  4450  to operable engagement with another one of the sensors that share the controller  4450 , for example. 
     In at least one example, as illustrated in  FIG.  92   , the closure trigger  32  can be operably coupled to the interface  4452  and can be configured to transition the interface  4452  between a plurality of positions and/or states. As illustrated in  FIG.  92   , the closure trigger  32  can be moveable between a plurality of positions, for example during a closure stroke, to transition the interface  4452  between a first position and/or state wherein the controller  4450  is electrically coupled to the sensor A, for example, a second position and/or state wherein the controller  4450  is electrically coupled to the sensor B, for example, and/or a third position and/or state wherein the controller  4450  is electrically coupled to the sensor C, for example. 
     In certain instances, a user may actuate the closure trigger  32  to capture tissue by the end effector  300 . Actuation of the closure trigger may cause the interface  4452  to be transitioned or shifted to transition the controller  4450  from operable engagement with the sensor A, for example, to operable engagement with the sensor B, for example, and/or from operable engagement with sensor B, for example, to operable engagement with sensor C, for example. 
     In certain instances, the controller  4450  may be coupled to the sensor A while the closure trigger  32  is in a first actuated position. As the closure trigger  32  is actuated past the first actuated position and toward a second actuated position, the controller  4450  may be decoupled from the sensor A. Alternatively, the controller  4450  may be coupled to the sensor A while the closure trigger  32  is in an unactuated position. As the closure trigger  32  is actuated past the unactuated position and toward a second actuated position, the controller  4450  may be decoupled from the sensor A. In certain instances, the controller  4450  may be coupled to the sensor B while the closure trigger  32  is in the second actuated position. As the closure trigger  32  is actuated past the second actuated position and toward a third actuated position, the controller  4450  may be decoupled from the sensor B. In certain instances, the controller  4450  may be coupled to the sensor C while the closure trigger  32  is in the third actuated position. 
     In certain instances, as illustrated in  FIG.  92   , the controller  4450  may include a plurality of electrical and/or mechanical contacts  4451  adapted for coupling engagement with the interface  4452 . The plurality of sensors of the surgical instrument  4400 , which share the controller  4450 , may each comprise one or more corresponding electrical and/or mechanical contacts  4453  adapted for coupling engagement with the interface  4452 , for example. 
     In certain instances, the processor  4422  may receive input from the plurality of sensors that share the controller  4450  while the sensors are coupled to the interface  4452 . For example, the processor  4422  may receive input from the sensor A while the sensor A is coupled to the controller  4450 ; the processor  4422  may receive input from the sensor B while the sensor B is coupled to the controller  4450 ; and the processor  4422  may receive input from the sensor C while the sensor C is coupled to the controller  4450 . In certain instances, the input can be a measurement value such as, for example, a measurement value of a tissue thickness of tissue captured by the end effector  300  ( FIGS.  1 ,  15   ). In certain instances, the processor  4422  may store the input from one or more of the sensors A, B, and C on the memory  4424 . In certain instances, the processor  4422  may perform various calculations based on the input provided by the sensors A, B, and C, for example. 
       FIGS.  93 A and  93 B  illustrate one aspect of an end effector  5300  comprising a staple cartridge  5306  that further comprises two light-emitting diodes  5310  (LEDs).  FIG.  93 A  illustrates an end effector  5300  comprising one LED  5310  located on either side of the cartridge deck  5308 .  FIG.  91 B  illustrates a three-quarter angle view of the end effector  5300  with the anvil  5302  in an open position, and one LED  5310  located on either side of the cartridge deck  5308 . The end effector  5300  is similar to the end effector  300  ( FIGS.  1 ,  15   ) described above. The end effector comprises an anvil  5302 , pivotally coupled to a jaw member or elongated channel  5304 . The elongated channel  5304  is configured to receive the staple cartridge  5306  therein. The staple cartridge  5306  comprises a plurality of staples (not shown). The plurality of staples are deployable from the staple cartridge  5306  during a surgical operation. The staple cartridge  5306  further comprises two LEDs  5310  mounted on the upper surface, or cartridge deck  5308  of the staple cartridge  5306 . The LEDs  5310  are mounted such that they will be visible when the anvil  5302  is in a closed position. Furthermore, the LEDs  5310  can be sufficiently bright to be visible through any tissue that may be obscuring a direct view of the LEDs  5310 . Additionally, one LED  5310  can be mounted on either side of the staple cartridge  5306  such that at least one LED  5310  is visible from either side of the end effector  5300 . The LED  5310  can be mounted near the proximal end of the staple cartridge  530 , as illustrated, or may be mounted at the distal end of the staple cartridge  5306 . 
     The LEDs  5310  may be in communication with a processor or controller, such as, for instance, controller  1500  ( FIG.  19   ). The controller  1500  can be configured to detect a property of tissue compressed by the anvil  5302  against the cartridge deck  5308 . Tissue that is enclosed by the end effector  5300  may change height as fluid within the tissue is exuded from the tissue&#39;s layers. Stapling the tissue before it has sufficiently stabilized may affect the effectiveness of the staples. Tissue stabilization is typically communicates as a rate of change, where the rate of change indicates how rapidly the tissue enclosed by the end effector is changing height. 
     The LEDs  5310  mounted to the staple cartridge  5306 , in the view of the operator of the instrument, can be used to indicate rate at which the enclosed tissue is stabilizing and/or whether the tissue has reached a stable state. The LEDs  5310  can, for example, be configured to flash at a rate that directly correlates to the rate of stabilization of the tissue, that is, can flash quickly initially, flash slower as the tissue stabilizes, and remain steady when the tissue is stable. Alternatively, the LEDs  5310  can flash slowly initially, flash more quickly as the tissue stabilizes, and turn off when the tissue is stable. 
     The LEDs  5310  mounted on the staple cartridge  5306  can be used additionally or optionally to indicate other information. Examples of other information include, but are not limited to: whether the end effector  5300  is enclosing a sufficient amount of tissue, whether the staple cartridge  5306  is appropriate for the enclosed tissue, whether there is more tissue enclosed than is appropriate for the staple cartridge  5306 , whether the staple cartridge  5306  is not compatible with the surgical instrument, or any other indicator that would be useful to the operator of the instrument. The LEDs  5310  can indicate information by either flashing at a particular rate, turning on or off at a particular instance, lighting in different colors for different information. The LEDs  5310  can alternatively or additionally be used to illuminate the area of operation. In some aspects the LEDs  5310  can be selected to emit ultraviolet or infrared light to illuminate information not visible under normal light, where that information is printed on the staple cartridge located in the end effector  5300  or on a tissue compensator (not illustrated). Alternatively or additionally, the staples can be coated with a fluorescing dye and the wavelength of the LEDs  5310  chosen so that the LEDs  5310  cause the fluorescing dye to glow. By illuminating the staples with the LEDs  5310  allows the operator of the instrument to see the staples after they have been driven. 
       FIGS.  94 A and  94 B  illustrate one aspect of the end effector  5300  comprising a staple cartridge  5356  that further comprises a plurality of LEDs  5360 .  FIG.  92 A  illustrates a side angle view of the end effector  5300  with the anvil  5302  in a closed position. The illustrated aspect comprises, by way of example, a plurality of LEDs  5360  located on either side of the cartridge deck  5358 .  FIG.  92 B  illustrates a three-quarter angle view of the end effector  5300  with the anvil  5302  in an open position, illustrating a plurality of LEDs  5360  located on either side of the cartridge deck  5358 . The staple cartridge  5356  comprises a plurality of LEDs  5360  mounted on the cartridge deck  5358  of the staple cartridge  5356 . The LEDs  5360  are mounted such that they will be visible when the anvil  5302  is in a closed position. Furthermore, the LEDs 6   530  can be sufficiently bright to be visible through any tissue that may be obscuring a direct view of the LEDs  5360 . Additionally, the same number of LEDs  5360  can be mounted on either side of the staple cartridge  5356  such that the same number of LEDs  5360  is visible from either side of the end effector  5300 . The LEDs  5360  can be mounted near the proximal end of the staple cartridge  5356 , as illustrated, or may be mounted at the distal end of the staple cartridge  5356 . 
     The LEDs  5360  may be in communication with a processor or controller, such as, for instance, controller  1500  of  FIG.  15   . The controller  1500  can be configured to detect a property of tissue compressed by the anvil  5302  against the cartridge deck  5358 , such as the rate of stabilization of the tissue, as described above. The LEDs  5360  can be used to indicate the rate at which the enclose tissue is stabilizing and/or whether the tissue has reached a stable state. The LEDs  5360  can be configured, for instance, to light in sequence starting at the proximal end of the staple cartridge  5356  with each subsequent LED  5360  lighting at the rate at which the enclosed tissue is stabilizing; when the tissue is stable, all the LEDs  5360  can be lit. Alternatively, the LEDs  5360  can light in sequence beginning at the distal end of the staple cartridge  5356 . Yet another alternative is for the LEDs  5360  to light in a sequential, repeating sequence, with the sequence starting at either the proximal or distal end of the LEDs  5360 . The rate at which the LEDs  5360  light and/or the speed of the repeat can indicate the rate at which the enclosed tissue is stabilizing. It is understood that these are only examples of how the LEDs  5360  can indicate information about the tissue, and that other combinations of the sequence in which the LEDs  5360  light, the rate at which they light, and or their on or off state are possible. It is also understood that the LEDs  5360  can be used to communicate some other information to the operator of the surgical instrument, or to light the work area, as described above. 
       FIGS.  95 A and  95 B  illustrate one aspect of the end effector  5300  comprising a staple cartridge  5406  that further comprises a plurality of LEDs  5410 .  FIG.  93 A  illustrates a side angle view of the end effector  5300  with the anvil  5302  in a closed position. The illustrated aspect comprises, by way of example, a plurality of LEDs  5410  from the proximal to the distal end of the staple cartridge  5406 , on either side of the cartridge deck  5408 .  FIG.  93 B  illustrates a three-quarter angle view of the end effector  5300  with the anvil  5302  in an open position, illustrating a plurality of LEDs  5410  from the proximal to the distal end of the staple cartridge  5406 , and on either side of the cartridge deck  5408 . The staple cartridge  5406  comprises a plurality of LEDs  5410  mounted on the cartridge deck  5408  of the staple cartridge  5406 , with the LEDs  5410  placed continuously from the proximal to the distal end of the staple cartridge  5406 . The LEDs  5410  are mounted such that they will be visible when the anvil  5302  is in a closed position. The same number of LEDs  5410  can be mounted on either side of the staple cartridge  5406  such that the same number of LEDs  5410  is visible from either side of the end effector  5300 . 
     The LEDs  5410  can be in communication with a processor or controller, such as, for instance, controller  1500  of  FIG.  15   . The controller  1500  can be configured to detect a property of tissue compressed by the anvil  5302  against the cartridge deck  5408 , such as the rate of stabilization of the tissue, as described above. The LEDs  5410  can be configured to be turned on or off in sequences or groups as desired to indicate the rate of stabilization of the tissue and/or that the tissue is stable. The LEDs  5410  can further be configured communicate some other information to the operator of the surgical instrument, or to light the work area, as described above. Additionally or alternatively, the LEDs  5410  can be configured to indicate which areas of the end effector  5300  contain stable tissue, and or what areas of the end effector  5300  are enclosing tissue, and/or if those areas are enclosing sufficient tissue. The LEDs  5410  can further be configured to indicate if any portion of the enclosed tissue is unsuitable for the staple cartridge  5406 . 
     Referring now primarily to  FIGS.  96  and  97   , the power assembly  2096  may include a power modulator control  2106  which may comprise, for example, one or more field-effect transistors (FETs), a Darlington array, an adjustable amplifier, and/or any other power modulator. The power assembly controller  2100  may actuate the power modulator control  2106  to set the power output of the battery  2098  to the power requirement of the interchangeable working assembly  2094  in response to the signal generated by working assembly controller  2102  while the interchangeable working assembly  2094  is coupled to the power assembly  2096 . 
     Still referring primarily to  FIGS.  96  and  97   , the power assembly controller  2100  can be configured to monitor power transmission from the power assembly  2096  to the interchangeable working assembly  2094  for the one or more signals generated by the working assembly controller  2102  of the interchangeable working assembly  2094  while the interchangeable working assembly  2094  is coupled to the power assembly  2096 . As illustrated in  FIG.  96   , the power assembly controller  2100  may utilize a voltage monitoring mechanism for monitoring the voltage across the battery  2098  to detect the one or more signals generated by the working assembly controller  2102 , for example. In certain instances, a voltage conditioner can be utilized to scale the voltage of the battery  2098  to be readable by an Analog to Digital Converter (ADC) of the power assembly controller  2100 . As illustrated in  FIG.  96   , the voltage conditioner may comprise a voltage divider  2108  which can create a reference voltage or a low voltage signal proportional to the voltage of the battery  2098  which can be measured and reported to the power assembly controller  2100  through the ADC, for example. 
     In other circumstances, as illustrated in  FIG.  97   , the power assembly  2096  may comprise a current monitoring mechanism for monitoring current transmitted to the interchangeable working assembly  2094  to detect the one or more signals generated by the working assembly controller  2102 , for example. In certain instances, the power assembly  2096  may comprise a current sensor  2110  which can be utilized to monitor current transmitted to the interchangeable working assembly  2094 . The monitored current can be reported to the power assembly controller  2100  through an ADC, for example. In other circumstances, the power assembly controller  2100  may be configured to simultaneously monitor both of the current transmitted to the interchangeable working assembly  2094  and the corresponding voltage across the battery  2098  to detect the one or more signals generated by the working assembly controller  2102 . The reader will appreciate that various other mechanisms for monitoring current and/or voltage can be utilized by the power assembly controller  2100  to detect the one or more signals generated by the working assembly controller  2102 ; all such mechanisms are contemplated by the present disclosure. 
     Referring to  FIG.  98   , the controller  13002  may generally comprise a processor  13008  (“microprocessor”) and one or more memory units  13010  operationally coupled to the processor  13008 . By executing instruction code stored in the memory  13010 , the processor  13008  may control various components of the surgical instrument  12200 , such as the motor  12216 , various drive systems, and/or a user display, for example. The controller  13002  may be implemented using integrated and/or discrete hardware elements, software elements, and/or a combination of both. Examples of integrated hardware elements may include processors, microprocessors, controllers, integrated circuits, application specific integrated circuits (ASIC), programmable logic devices (PLD), digital signal processors (DSP), field programmable gate arrays (FPGA), logic gates, registers, semiconductor devices, chips, microchips, chip sets, controllers, system-on-chip (SoC), and/or system-in-package (SIP). Examples of discrete hardware elements may include circuits and/or circuit elements such as logic gates, field effect transistors, bipolar transistors, resistors, capacitors, inductors, and/or relays. In certain instances, the controller  13002  may include a hybrid circuit comprising discrete and integrated circuit elements or components on one or more substrates, for example. In certain instances, the controller  13002  may be a single core or multicore controller LM4F230H5QR as described in connection with  FIGS.  15 - 17 B . 
     In various forms, the motor  12216  may be a DC brushed driving motor having a maximum rotation of, approximately, 25,000 RPM, for example. In other arrangements, the motor  12216  may include a brushless motor, a cordless motor, a synchronous motor, a stepper motor, or any other suitable electric motor. A battery  12218  (or “power source” or “power pack”), such as a Li ion battery, for example, may be coupled to the housing  12212  to supply power to the motor  12216 , for example. 
     Referring again to  FIG.  98   , the surgical instrument  12200  may include a motor controller  13005  in operable communication with the controller  13002 . The motor controller  13005  can be configured to control a direction of rotation of the motor  12216 . In certain instances, the motor controller  13005  may be configured to determine the voltage polarity applied to the motor  12216  by the battery  12218  and, in turn, determine the direction of rotation of the motor  12216  based on input from the controller  13002 . For example, the motor  12216  may reverse the direction of its rotation from a clockwise direction to a counterclockwise direction when the voltage polarity applied to the motor  12216  by the battery  12218  is reversed by the motor controller  13005  based on input from the controller  13002 . In addition, the motor  12216  can be operably coupled to an articulation drive which can be driven by the motor  12216  distally or proximally depending on the direction in which the motor  12216  rotates, for example. Furthermore, the articulation drive can be operably coupled to the end effector  12208  such that, for example, the axial translation of the articulation drive proximally may cause the end effector  12208  to be articulated in the counterclockwise direction, for example, and/or the axial translation of the articulation drive distally may cause the end effector  12208  to be articulated in the clockwise direction, for example. 
     In the aspect illustrated in  FIG.  99   , an interface  3001  comprises multiple switches  3004 A-C,  3084 B wherein each of the switches  3004 A-C is coupled to the controller  3002  via one of three electrical circuits  3006 A-C, respectively, and switch  3084 B is coupled to the controller  3002  via circuit  3084 A. The reader will appreciate that other combinations of switches and circuits can be utilized with the interface  3001 . 
     Further to the above, the controller  3002  may comprise a processor  3008  and/or one or more memory  3010  units. By executing instruction code stored in the memory  3010 , the processor  3008  may control various components of the surgical instrument, such as the electric motor  1102  and/or a user display. The controller  3002  may be implemented using integrated and/or discrete hardware elements, software elements, and/or a combination of both. Examples of integrated hardware elements may include processors, microprocessors, controllers, integrated circuits, application specific integrated circuits (ASIC), programmable logic devices (PLD), digital signal processors (DSP), field programmable gate arrays (FPGA), logic gates, registers, semiconductor devices, chips, microchips, chip sets, controller, system-on-chip (SoC), and/or system-in-package (SIP). Examples of discrete hardware elements may include circuits and/or circuit elements (e.g., logic gates, field effect transistors, bipolar transistors, resistors, capacitors, inductors, relay and so forth). In other aspects, the controller  3002  may include a hybrid circuit comprising discrete and integrated circuit elements or components on one or more substrates, for example. 
     Referring again to  FIG.  99   , the surgical instrument  1010  may include a motor controller  3005  in operable communication with the controller  3002 . The motor controller  3005  can be configured to control a direction of rotation of the electric motor  1102 . For example, the electric motor  1102  can be powered by a battery such as, for example, the battery  1104  and the controller  3002  may be configured to determine the voltage polarity applied to the electric motor  1102  by the battery  1104  and, in turn, the direction of rotation of the electric motor  1102  based on input from the controller  3002 . For example, the electric motor  1102  may reverse the direction of its rotation from a clockwise direction to a counterclockwise direction when the voltage polarity applied to the electric motor  1102  by the battery  1104  is reversed by the motor controller  3005  based on input from the controller  3002 . Examples of suitable motor controllers are described elsewhere in this document and include but are not limited to the driver  7010  ( FIG.  100   ). 
     In addition, as described elsewhere in this document in greater detail, the electric motor  1102  can be operably coupled to an articulation drive. In use, the electric motor  1102  can drive the proximal articulation drive distally or proximally depending on the direction in which the electric motor  1102  rotates. Furthermore, the proximal articulation drive can be operably coupled to the end effector  1300  such that, for example, the axial translation of the proximal articulation drive  10030  proximally may cause the end effector  1300  to be articulated in the counterclockwise direction, for example, and/or the axial translation of the proximal articulation drive  10030  distally may cause the end effector  1300  to be articulated in the clockwise direction, for example. 
     Further to the above, referring again to  FIG.  99   , the interface  3001  can be configured such that the switch  3004 A can be dedicated to clockwise articulation of the end effector  1300  and the switch  3004 B can be dedicated to counterclockwise articulation of the end effector  1300 . For example, the operator may articulate the end effector  1300  in the clockwise direction by closing the switch  3004 A which may signal the controller  3002  to cause the electric motor  1102  to rotate in the clockwise direction thereby, as a result, causing the proximal articulation drive  10030  to be advanced distally and causing the end effector  1300  to be articulated in the clockwise direction. In another example, the operator may articulate the end effector  1300  in the counterclockwise direction by closing the switch  3004 B which may signal the controller  3002  to cause the electric motor  1102  to rotate in the counterclockwise direction, for example, and retracting the proximal articulation drive  10030  proximally to articulate the end effector  1300  to in the counterclockwise direction. 
     As shown in  FIG.  100   , a sensor arrangement  7002  provides a unique position signal corresponding to the location of the longitudinally-movable drive member  1111 . The electric motor  1102  can include a rotatable shaft  7016  that operably interfaces with a gear assembly  7014  that is mounted in meshing engagement with a with a set, or rack, of drive teeth on the longitudinally-movable drive member  1111 . With reference also to  FIG.  101   , the sensor element  7026  may be operably coupled to the gear assembly  7106  such that a single revolution of the sensor element  7026  corresponds to some linear longitudinal translation of the longitudinally-movable drive member  1111 , as described in more detail hereinbelow. In one aspect, an arrangement of gearing and sensors can be connected to the linear actuator via a rack and pinion arrangement, or a rotary actuator via a spur gear or other connection. For aspects comprising a rotary screw-drive configuration where a larger number of turns would be required, a high reduction gearing arrangement between the drive member and the sensor, like a worm and wheel, may be employed. 
     In accordance one aspect of the present disclosure, the sensor arrangement  7002  for the absolute positioning system  7000  provides a position sensor  7012  that is more robust for use with surgical devices. By providing a unique position signal or value for each possible actuator position, such arrangement eliminates the need for a zeroing or calibration step and reduces the possibility of negative design impact in the cases where noise or power brown-out conditions may create position sense errors as in conventional rotary encoder configurations. 
     In one aspect, the sensor arrangement  7002  for the absolute positioning system  7000  replaces conventional rotary encoders typically attached to the motor rotor and replaces it with a position sensor  7012  which generates a unique position signal for each rotational position in a single revolution of a sensor element associated with the position sensor  7012 . Thus, a single revolution of a sensor element associated with the position sensor  7012  is equivalent to a longitudinal linear displacement d 1  of the of the longitudinally-movable drive member  1111 . In other words, d 1  is the longitudinal linear distance that the longitudinally-movable drive member  1111  moves from point “a” to point “b” after a single revolution of a sensor element coupled to the longitudinally-movable drive member  1111 . The sensor arrangement  7002  may be connected via a gear reduction that results in the position sensor  7012  completing only a single turn for the full stroke of the longitudinally-movable drive member  1111 . With a suitable gear ratio, the full stroke of the longitudinally-movable drive member  1111  can be represented in one revolution of the position sensor  7012 . 
     A series of switches  7022   a  to  7022   n , where n is an integer greater than one, may be employed alone or in combination with gear reduction to provide a unique position signal for more than one revolution of the position sensor  7012 . The state of the switches  7022   a - 7022   n  are fed back to a controller  7004  which applies logic to determine a unique position signal corresponding to the longitudinal linear displacement d 1 +d 2 + . . . dn of the longitudinally-movable drive member  1111 . 
     Accordingly, the absolute positioning system  7000  provides an absolute position of the longitudinally-movable drive member  1111  upon power up of the instrument without retracting or advancing the longitudinally-movable drive member  1111  to a reset (zero or home) position as may be required with conventional rotary encoders that merely count the number of steps forwards or backwards that motor has taken to infer the position of a device actuator, drive bar, knife, and the like. 
     In various aspects, the position sensor  7012  of the sensor arrangement  7002  may comprise one or more magnetic sensor, analog rotary sensor like a potentiometer, array of analog Hall-effect elements, which output a unique combination of position signals or values, among others, for example. 
     In various aspects, the controller  7004  may be programmed to perform various functions such as precise control over the speed and position of the knife and articulation systems. Using the known physical properties, the controller  7004  can be designed to simulate the response of the actual system in the software of the controller  7004 . The simulated response is compared to (noisy and discrete) measured response of the actual system to obtain an “observed” response, which is used for actual feedback decisions. The observed response is a favorable, tuned, value that balances the smooth, continuous nature of the simulated response with the measured response, which can detect outside influences on the system. 
     In various aspects, the absolute positioning system  7000  may further comprise and/or be programmed to implement the following functionalities. A feedback controller, which can be one of any feedback controllers, including, but not limited to: PID, state feedback and adaptive. A power source converts the signal from the feedback controller into a physical input to the system, in this case voltage. Other examples include, but are not limited to pulse width modulated (PWMed) voltage, current and force. The electric motor  1102  may be a brushed DC motor with a gearbox and mechanical links to an articulation or knife system. Other sensor(s)  7018  may be provided to measure physical parameters of the physical system in addition to position measured by the position sensor  7012 . Since it is a digital signal (or connected to a digital data acquisition system) its output will have finite resolution and sampling frequency. A compare and combine circuit may be provided to combine the simulated response with the measured response using algorithms such as, without limitation, weighted average and theoretical control loop that drives the simulated response towards the measured response. Simulation of the physical system takes in account of properties like mass, inertial, viscous friction, inductance resistance, etc. to predict what the states and outputs of the physical system will be by knowing the input. In one aspect, the controller  7004  may be a single core or multicore controller LM4F230H5QR as described in connection with  FIGS.  15 - 17 B . 
     In one aspect, the driver  7010  may be a A3941 available from Allegro Microsystems, Inc. The A3941 driver  7010  is a full-bridge controller for use with external N-channel power metal oxide semiconductor field effect transistors (MOSFETs) specifically designed for inductive loads, such as brush DC motors. The driver  7010  comprises a unique charge pump regulator provides full (&gt;10 V) gate drive for battery voltages down to 7 V and allows the A3941 to operate with a reduced gate drive, down to 5.5 V. A bootstrap capacitor may be employed to provide the above-battery supply voltage required for N-channel MOSFETs. An internal charge pump for the high-side drive allows DC (100% duty cycle) operation. The full bridge can be driven in fast or slow decay modes using diode or synchronous rectification. In the slow decay mode, current recirculation can be through the high-side or the lowside FETs. The power FETs are protected from shoot-through by resistor adjustable dead time. Integrated diagnostics provide indication of undervoltage, overtemperature, and power bridge faults, and can be configured to protect the power MOSFETs under most short circuit conditions. Other motor drivers may be readily substituted for use in the absolute positioning system  7000 . Accordingly, the present disclosure should not be limited in this context. 
     Having described a general architecture for implementing various aspects of an absolute positioning system  7000  for a sensor arrangement  7002 , the disclosure now turns to  FIGS.  101 - 103    for a description of one aspect of a sensor arrangement for the absolute positioning system  7000 . In the aspect illustrated in  FIG.  101   , the sensor arrangement  7002  comprises a position sensor  7100 , a magnet  7102  sensor element, a magnet holder  7104  that turns once every full stroke of the longitudinally-movable drive member  1111  ( FIG.  100   ), and a gear assembly  7106  to provide a gear reduction. A structural element such as bracket  7116  is provided to support the gear assembly  7106 , the magnet holder  7104 , and the magnet  7102 . The position sensor  7100  comprises one or more than one magnetic sensing elements such as Hall elements and is placed in proximity to the magnet  7102 . Accordingly, as the magnet  7102  rotates, the magnetic sensing elements of the position sensor  7100  determine the absolute angular position of the magnet  7102  over one revolution. 
     In various aspects, any number of magnetic sensing elements may be employed on the absolute positioning system  7000 , such as, for example, magnetic sensors classified according to whether they measure the total magnetic field or the vector components of the magnetic field. The techniques used to produce both types of magnetic sensors encompass many aspects of physics and electronics. The technologies used for magnetic field sensing include search coil, fluxgate, optically pumped, nuclear precession, SQUID, Hall-effect, anisotropic magnetoresistance, giant magnetoresistance, magnetic tunnel junctions, giant magnetoimpedance, magnetostrictive/piezoelectric composites, magnetodiode, magnetotransistor, fiber optic, magnetooptic, and microelectromechanical systems-based magnetic sensors, among others. 
     In the illustrated aspect, the gear assembly  7106  comprises a first gear  7108  and a second gear  7110  in meshing engagement to provide a 3:1 gear ratio connection. A third gear  7112  rotates about shaft  7114 . The third gear is in meshing engagement with the longitudinally-movable drive member  1111  and rotates in a first direction as the longitudinally-movable drive member  1111  advances in a distal direction D and rotates in a second direction as the longitudinally-movable drive member  1111  retracts in a proximal direction P. The second gear  7110  also rotates about the shaft  7114  and therefore, rotation of the second gear  7110  about the shaft  7114  corresponds to the longitudinal translation of the longitudinally-movable drive member  1111 . Thus, one full stroke of the longitudinally-movable drive member  1111  in either the distal or proximal directions D, P corresponds to three rotations of the second gear  7110  and a single rotation of the first gear  7108 . Since the magnet holder  7104  is coupled to the first gear  7108 , the magnet holder  7104  makes one full rotation with each full stroke of the longitudinally-movable drive member  1111 . 
       FIG.  102    is an exploded perspective view of the sensor arrangement  7002  for the absolute positioning system  7000  showing a circuit  1106  and the relative alignment of the elements of the sensor arrangement  7002 , according to one aspect. The position sensor  7100  (not shown in this view) is supported by a position sensor holder  7118  defining an aperture  7120  suitable to contain the position sensor  7100  in precise alignment with a magnet  7102  rotating below. The fixture is coupled to the bracket  7116  and to the circuit  1106  and remains stationary while the magnet  7102  rotates with the magnet holder  7104 . A hub  7122  is provided to mate with the first gear  7108  and the magnet holder  7104 . 
       FIG.  103    is a schematic diagram of one aspect of a position sensor  7100  sensor for an absolute positioning system  7000  comprising a magnetic rotary absolute positioning system, according to one aspect. In one aspect, the position sensor  7100  may be implemented as an AS5055EQFT single-chip magnetic rotary position sensor available from Austria Microsystems, AG. The position sensor  7100  is interfaced with the controller  7004  to provide an absolute positioning system  7000 . The position sensor  7100  is a low voltage and low power component and includes four Hall-effect elements  7128 A,  7128 B,  7128 C,  7128 D in an area  7130  of the position sensor  7100  that is located above the magnet  7102  ( FIGS.  99 ,  100   ). A high resolution ADC  7132  and a smart power management controller  7138  are also provided on the chip. A CORDIC processor  7136  (for COordinate Rotation DIgital Computer), also known as the digit-by-digit method and Volder&#39;s algorithm, is provided to implement a simple and efficient algorithm to calculate hyperbolic and trigonometric functions that require only addition, subtraction, bitshift, and table lookup operations. The angle position, alarm bits and magnetic field information are transmitted over a standard serial communication interface such as an SPI interface  7134  to the controller  7004 . The position sensor  7100  provides 12 or 14 bits of resolution. The position sensor  7100  may be an AS5055 chip provided in a small QFN 16-pin 4×4×0.85 mm package. 
     The Hall-effect elements  7128 A,  7128 B,  7128 C,  7128 D are located directly above the rotating magnet. The Hall-effect is a well known effect and will not be described in detail herein for the sake of conciseness and clarity of disclosure. Generally, the Hall-effect is the production of a voltage difference (the Hall voltage) across an electrical conductor, transverse to an electric current in the conductor and a magnetic field perpendicular to the current. It was discovered by Edwin Hall in 1879. The Hall coefficient is defined as the ratio of the induced electric field to the product of the current density and the applied magnetic field. It is a characteristic of the material from which the conductor is made, since its value depends on the type, number, and properties of the charge carriers that constitute the current. In the AS5055 position sensor  7100 , the Hall-effect elements  7128 A,  7128 B,  7128 C,  7128 D are capable producing a voltage signal that is indicative of the absolute position of the magnet  7102  ( FIGS.  186 ,  187   ) in terms of the angle over a single revolution of the magnet  7102 . This value of the angle, which is unique position signal, is calculated by the CORDIC processor  7136  is stored onboard the AS5055 position sensor  7100  in a register or memory. The value of the angle that is indicative of the position of the magnet  7102  over one revolution is provided to the controller  7004  in a variety of techniques, e.g., upon power up or upon request by the controller  7004 . 
     The AS5055 position sensor  7100  requires only a few external components to operate when connected to the controller  7004 . Six wires are needed for a simple application using a single power supply: two wires for power and four wires  7140  for the SPI interface  7134  with the controller  7004 . A seventh connection can be added in order to send an interrupt to the controller  7004  to inform that a new valid angle can be read. 
     Upon power-up, the AS5055 position sensor  7100  performs a full power-up sequence including one angle measurement. The completion of this cycle is indicated as an INT output  7142  and the angle value is stored in an internal register. Once this output is set, the AS5055 position sensor  7100  suspends to sleep mode. The controller  7004  can respond to the INT request at the INT output  7142  by reading the angle value from the AS5055 position sensor  7100  over the SPI interface  7134 . Once the angle value is read by the controller  7004 , the INT output  7142  is cleared again. Sending a “read angle” command by the SPI interface  7134  by the controller  7004  to the position sensor  7100  also automatically powers up the chip and starts another angle measurement. As soon as the controller  7004  has completed reading of the angle value, the INT output  7142  is cleared and a new result is stored in the angle register. The completion of the angle measurement is again indicated by setting the INT output  7142  and a corresponding flag in the status register. 
     Due to the measurement principle of the AS5055 position sensor  7100 , only a single angle measurement is performed in very short time (˜600 μs) after each power-up sequence. As soon as the measurement of one angle is completed, the AS5055 position sensor  7100  suspends to power-down state. An on-chip filtering of the angle value by digital averaging is not implemented, as this would require more than one angle measurement and consequently, a longer power-up time which is not desired in low power applications. The angle jitter can be reduced by averaging of several angle samples in the controller  7004 . For example, an averaging of 4 samples reduces the jitter by 6 dB (50%). 
     As discussed above, the electric motor  1102  positioned within the handle  1042  of surgical instrument system  1000  can be utilized to advance and/or retract the firing system of the shaft assembly  1200 , including firing members  1272  and  1280 , for example, relative to the end effector  1300  of the shaft assembly  1200  in order to staple and/or incise tissue captured within the end effector  1300 . In various circumstances, it may be desirable to advance the firing members  1272  and  1280  at a desired speed, or within a range of desired speeds. Likewise, it may be desirable to retract the firing members  1272  and  1280  at a desired speed, or within a range of desired speeds. In various circumstances, the controller  7004  of the handle  1042 , for example, and/or any other suitable controller, can be configured to control the speed of the firing members  1272  and  1280 . In some circumstances, the controller can be configured to predict the speed of the firing members  1272  and  1280  based on various parameters of the power supplied to the electric motor  1102 , such as voltage and/or current, for example, and/or other operating parameters of the electric motor  1102 . The controller can also be configured to predict the current speed of the firing members  1272  and  1280  based on the previous values of the current and/or voltage supplied to the electric motor  1102 , and/or previous states of the system like velocity, acceleration, and/or position. Furthermore, the controller can also be configured to sense the speed of the firing members  1272  and  1280  utilizing the absolute positioning sensor system described above, for example. In various circumstances, the controller can be configured to compare the predicted speed of the firing members  1272  and  1280  and the sensed speed of the firing members  1272  and  1280  to determine whether the power to the electric motor  1102  should be increased in order to increase the speed of the firing members  1272  and  1280  and/or decreased in order to decrease the speed of the firing members  1272  and  1280 . U.S. Pat. No. 8,210,411, entitled MOTOR-DRIVEN SURGICAL CUTTING INSTRUMENT, which is incorporated herein by reference in its entirety. U.S. Pat. No. 7,845,537, entitled SURGICAL INSTRUMENT HAVING RECORDING CAPABILITIES, which is incorporated herein by reference in its entirety. 
     Using the physical properties of the instruments disclosed herein, turning now to  FIGS.  104  and  105   , a controller, such as controller  7004 , for example, can be designed to simulate the response of the actual system of the instrument in the software of the controller. The simulated response is compared to a (noisy and discrete) measured response of the actual system to obtain an “observed” response, which is used for actual feedback decisions. The observed response is a favorable, tuned, value that balances the smooth, continuous nature of the simulated response with the measured response, which can detect outside influences on the system. With regard to  FIGS.  104  and  105   , a firing element, or cutting element, in the end effector  1300  of the shaft assembly  1200  can be moved at or near a target velocity, or speed. The systems disclosed in  FIGS.  102  and  103    can be utilized to move the cutting element at a target velocity. The systems can include a feedback controller  4200 , which can be one of any feedback controllers, including, but not limited to a PID, a State Feedback, LQR, and/or an Adaptive controller, for example. The systems can further include a power source. The power source can convert the signal from the feedback controller  4200  into a physical input to the system, in this case voltage, for example. Other examples include, but are not limited to, pulse width modulated (PWM) voltage, frequency modulated voltage, current, torque, and/or force, for example. 
     With continued reference to  FIGS.  104  and  105   , the physical system referred to therein is the actual drive system of the instrument configured to drive the firing member, or cutting member. One example is a brushed DC motor with gearbox and mechanical links to an articulation and/or knife system. Another example is the electric motor  1102  disclosed herein that operates the firing member  10060  and the articulation driver  10030 , for example, of an interchangeable shaft assembly. The outside influence  4201  referred to in  FIGS.  104  and  105    is the unmeasured, unpredictable influence of things like tissue, surrounding bodies and friction on the physical system, for example. Such outside influence can be referred to as drag and can be represented by a motor  4202  which acts in opposition to the electric motor  1102 , for example. In various circumstances, outside influence, such as drag, is the primary cause for deviation of the simulation of the physical system from the actual physical system. The systems depicted in  FIGS.  104  and  105    and further discussed below can address the differences between the predicted behavior of the firing member, or cutting member, and the actual behavior of the firing member, or cutting member. 
     With continued reference to  FIGS.  104  and  105   , the discrete sensor referred to therein measures physical parameters of the actual physical system. One aspect of such a discrete sensor can include an absolute positioning sensor and system described herein, such as the magnet  7102 . As the output of such a discrete sensor can be a digital signal (or connected to a digital data acquisition system) its output may have finite resolution and sampling frequency. The output of the discrete sensor can be supplied to a controller, such as controller  7004 , for example. In various circumstances, the controller can combine the simulated, or estimated, response with the measured response. In certain circumstances, it may be useful to use enough measured response to ensure that the outside influence is accounted for without making the observed response unusably noisy. Examples for algorithms that do so include a weighted average and/or a theoretical control loop that drives the simulated response towards the measured response, for example. Ultimately, further to the above, the simulation of the physical system takes in account of properties like mass, inertial, viscous friction, and/or inductance resistance, for example, to predict what the states and outputs of the physical system will be by knowing the input.  FIG.  103    shows an addition of evaluating and measuring the current supplied to operate the actual system, which is yet another parameter that can be evaluated for controlling the speed of the cutting member, or firing member, of the shaft assembly  1200 , for example. By measuring current in addition to or in lieu of measuring the voltage, in certain circumstances, the physical system can be made more accurate. Nonetheless, the ideas disclosed herein can be extended to the measurement of other state parameters of other physical systems. 
       FIG.  106    illustrates a perspective view of a surgical instrument  5500  according to various aspects described herein. The surgical instrument  5500  is similar to those described hereinabove in that the surgical instrument  5500  includes an elongated channel configured to support a staple cartridge, an anvil pivotably connected to the elongated channel, a closure member mechanically coupled to the anvil, a knife mechanically coupled to the staple cartridge, an electric motor mechanically coupled to the closure member and/or the knife, a motor controller electrically coupled to the motor, and a control circuit electrically coupled to the motor controller. The surgical instrument  5500  is also similar to those described hereinabove in that the surgical instrument  5500  also includes sensors which are collectively configured to sense or measure a closing force, a firing force, a current drawn by the electric motor, an impedance of tissue positioned between the elongated channel and the anvil, a position of the anvil relative to the elongated channel, a position of the knife, or any combination thereof. The surgical instrument  5500  is also similar to those described hereinabove in that the surgical instrument  5500  also includes algorithms such as closing algorithms, firing algorithms, motor control algorithms, or any combination thereof, which operate to dynamically adjust the operation of the surgical instrument  5500 . However, the surgical instrument  5500  is different from those described hereinabove in that the surgical instrument  5500  further includes one or more additional algorithms (in addition to those described hereinabove) which provide additional control functionality for the surgical instrument  5500 , as described hereinbelow. 
     In general, the surgical instrument  5500  may utilize one or more closing algorithms to control a closing motion which clamps the jaws to tissue positioned therebetween and/or one or more firing algorithms to control a firing motion which staples and severs the tissue clamped between the jaws. In operation, a given sensor senses or measures a given parameter (e.g., a closing force, a firing force, and/or any combination thereof) and outputs a signal indicative of the sensed/measured parameter. The output signal can be an analog signal or a digital signal. For instances where the signal output by the sensor is an analog signal, the analog signal is input to an analog-to-digital (A/D) converter which outputs a digital signal indicative of the analog signal. The digital signal is then input to a controller resident in the surgical instrument  5500 . For instances where the signal output by the sensor is a digital signal, there is no need for an A/D conversion and the digital signal output by the sensor can be input to the controller. Upon the occurrence of a trigger, a threshold and/or an event, the controller may modify or adjust a closing algorithm, or initiate a different closing algorithm, thereby automatically changing the operation of the surgical instrument  5500  during a closing motion. Similarly, upon the occurrence of a trigger, a threshold and/or an event, the controller may modify or adjust a firing algorithm, or initiate a different firing algorithm, thereby automatically changing the operation of the surgical instrument  5500  during a firing motion. 
     According to various aspects, the trigger, threshold or event is defined by the sensed/measured closing force. According to other aspects, the trigger, threshold or event is defined by a parameter related to the sensed/measured closing force. Similarly, according to various aspects, the trigger, threshold or event is defined by the sensed/measured firing force. According to other aspects, the trigger, threshold or event is defined by a parameter related to the sensed/measured firing force. 
       FIG.  107    illustrates a method  1010  of controlling a closing motion of the surgical instrument  5500  according to various aspects. The process starts when a closing motion is initiated  5512 . The closing motion may be initiated, for example, by pulling a closing trigger toward a handle A sensor resident with the surgical instrument  5500  senses/measures  5514  a closing force. The closing force may be, for example, a force experienced by tissue clamped between the jaws of the surgical instrument  5500 , a force experienced by the jaws of the surgical instrument  5500  (e.g., by the anvil and/or the elongated channel), a force experienced by the closure tube of the surgical instrument  5500 , and/or any combinations thereof. 
     In response to the closing force, the sensor outputs  5516  a closing force signal, which is indicative of the closing force sensed/measured  5514  by the sensor. Depending on the configuration of the sensor, the closing force signal can be an analog signal or a digital signal. Upon determining  5518  whether the closing force signal is either an analog signal or a digital signal, the process proceeds along the corresponding branch. When the determination  5518  is that the closing force signal is an analog signal, the process proceeds along the analog branch, where the analog signal is received by an A/D converter, converted  5520  to a digital signal representative of the analog signal by the A/D converter and the digital signal is output by the A/D converter. When the determination  5518  is that the closing force signal is a digital signal, the process proceeds along the digital branch because there is no need for an A/D conversion  5520  when the closing force signal is a digital signal. 
     The closing force signal which is a digital signal representative of the closing force sensed/measured  5514  by the sensor is received by a controller. The controller utilizes the digital signal and determines  5522  whether the closing force sensed/measured  5514  by the sensor reaches or exceeds a predetermined threshold. The controller may make this determination  5522  based on a comparison of a magnitude of the closing force sensed/measured  5514  by the sensor and the predetermined threshold, based on a comparison of an amplitude of the closing force signal output  5516  by the sensor and a predetermined threshold, or any combination thereof. 
     When the controller determines  5522  that the closing force sensed/measured  5514  by the sensor has not reached or exceeded the predetermined threshold, the closing motion originally initiated  5512  is continued  5524  along with interim processes  5514 - 5522 . When the controller determines  5522  that the closing force sensed/measured  5514  by the sensor has reached or exceeded the predetermined threshold, the controller changes  5526  the closing motion. According to some aspects, the controller may change the closing motion by modifying or adjusting a closing algorithm being executed by the controller to cause the closing motion to be slowed down, paused or stopped to prevent the surgical instrument  5500  from experiencing excessive forces. According to other aspects, the controller may change the closing motion by executing a different closing algorithm which causes the closing motion to be slowed down, paused or stopped to prevent the surgical instrument  5500  from experiencing excessive forces. In either case, the closing motion may be slowed down, stopped or paused by having the controller communicate a slow down signal, a stop signal or a pause signal to the motor controller to slow down, stop or pause the rotation of the motor(s) which drive the closing of the jaws of the surgical instrument  5500 . 
     Upon changing the closing motion  5526 , when the change of the closing motion  5526  is a slowing down of the closing motion (a slowing down of the rotation of the motor(s) which drive the closing of the jaws), the process continues  5528  the closing motion originally initiated  5512  but at a reduced speed and the interim process  5514 - 5522  is continued but the closing of the jaws occurs at a reduced speed. When the change of the closing motion  5526  is a stopping or pausing of the closing motion (a stopping or pausing of the rotation of the motor(s) which drive the closing of the jaws), the process suspends or terminates  5530  the closing motion. 
       FIG.  108    illustrates an example graph  5540  showing a curve  5542  representative of a closing force F over time t for various aspects of the surgical instrument  5500 . The closing force F is shown along the vertical axis and the time t is shown along the horizontal axis. Stated differently, the curve  5542  is a graphical representation of the closing force signal at various times during a closing motion. The curve  5542  may be generated mathematically by the controller based on the closing force signal(s) received by the controller. The closing force F represented on the vertical axis may be a force experienced by tissue clamped between the jaws of the surgical instrument  5500 , a force experienced by the jaws of the surgical instrument  5500  (e.g., by the anvil and/or the elongated channel), a force experienced by the closure tube of the surgical instrument  5500 , and/or any combinations thereof. The closing force F can be measured in any suitable manner, either directly or indirectly. For example, according to various aspects, the closing force F can be measured directly by a sensor (e.g., a strain gauge) positioned on the anvil, on the elongated channel, on the closure tube, or indirectly by an impedance of the tissue, a current draw of the motor, and/or any combinations thereof. 
     According to various aspects, the operation of the surgical instrument  5500  may be controlled by monitoring the amplitude of the closing force signal and changing the closing motion when the amplitude of the closing force signal reaches or exceeds a predetermined threshold. With reference to  FIG.  107   , for example, the closing force amplitude Fcrit may be determined to be an excessive amount of the closing force F experienced by the surgical instrument  5500 . Upon the occurrence of the amplitude of the closing force signal reaching or exceeding the closing force amplitude Fcrit, an algorithm, such as the method  1010  of controlling a closing motion of the surgical instrument  5500  according to various aspects illustrated in  FIG.  106   , may operate to change the closing motion by slowing down, pausing or stopping the motor(s) of the surgical instrument  5500  to prevent the surgical instrument  5500  from experiencing excessive forces. 
     The curve  5542  provides a useful representation of how the closing force F varies over time t. The change in the closing force F over time t (i.e., the rate of change of the closing force F) may provide useful feedback to the control circuit to control the jaw closing mechanism of the surgical instrument  5500 . The change in the closing force F over time t may be represented as a derivative of the curve  5542  and may be approximated over short periods of time by the equation Slope S=ΔF/Δt, where ΔF is the change of the closing force F and Δt is the change of the time t. The curve  5542  is representative of an analog signal over time which is sampled and converted to a digital value by an A/D converter as the jaws are closed/opened. Once the analog signal is digitized, the control circuit may thereafter determine the slope of the closing force signal represented by the curve  5542  at any point during the closing motion. 
     According to various aspects, the operation of the surgical instrument  5500  may be controlled by monitoring the slope of the curve  5542  (the slope of the closing force signal) and changing the closing motion based on the value of the slope. In general, with reference to  FIG.  108   , the slope of the curve  5542  may be approximated by the equation S=ΔF/Δt, where ΔF is the change of the closing force F and Δt is the change of the time t. Those skilled in the art will appreciate that the instantaneous slope may be calculated by taking the derivative of the curve  5542 . Over time t, the slope S may be monitored by the control circuit and utilized by the control circuit to control the operation of the surgical instrument  5500 . For example, an algorithm of the surgical instrument  5500  may be configured to monitor the change of the closing force F over the time t, stop or pause the closing motion when the slope of the curve  5542  reaches or exceeds a first predetermined threshold, then restart the closing motion when the slope of the curve  5542  reaches or falls below a second predetermined threshold. The value of the slope C=ΔF 1 /Δt 1  (a positive value) shown in  FIG.  108    may be determined by the controller and may represent the first predetermined threshold. Similarly, the value of the slope D=ΔF 2 /Δt 2  (a negative value) shown in  FIG.  108    may be determined by the controller and may represent the second predetermined threshold. Thus, according to various aspects, the algorithm can control the operation of the control circuit based on the determined slope, whether instantaneous or approximated. 
     For the example graph  5540  shown in  FIG.  108   , at time t=0 the jaws are in the open position and there is no closing force F experienced by the jaws. Once tissue is positioned between the jaws, as the jaws are moved toward a closed position, the jaws come in contact with tissue and begin to compress the tissue. Thus, as the time moves from the time t=0, the closing force F experienced by the jaws begins to increase. An algorithm of the surgical instrument  5500  may automatically stop or pause a further closing of the jaws based on a trigger, a threshold and/or an event. For example, when the change of the closing force F over time t reaches or exceeds a predetermined threshold (e.g., the slope C is greater than the predetermined threshold), the algorithm may automatically stop or pause further closing of the jaws. Alternatively, when the closing force F reaches or exceeds another predetermined threshold (e.g., the closing force F is greater than Fcrit), the algorithm may automatically stop or pause further closing of the jaws. 
     After the closing of the jaws is stopped or paused, fluid may continue to be displaced from the tissue over time thereby causing the pressure experienced by the jaws to decrease. The control algorithm may automatically re-enable a further closing of the jaws based on a trigger, a threshold or and/or an event. For example, when the change of the closing force F over time t reaches or falls below a predetermined threshold (e.g., the slope D is more negative than the predetermined threshold), the algorithm may automatically restart a further closing of the jaws. A portion of the curve  5542  having the slope D may be indicative of a stabilized tissue condition. Alternatively, when a predetermined period of time has passed since the closing of the jaws was stopped or paused (e.g., the time period t 1  in  FIG.  108   ), the algorithm may automatically restart a further closing of the jaws. The predetermined period of time may be considered an adequate amount of time for an adequate amount of tissue creep to occur and/or for the tissue to reach a stabilized condition. 
     The above-described automatic stopping or pausing and automatic restarting may be repeated any number of times. As more pressure is applied to the tissue (i.e., the jaws experience more force), the amount of time which occurs between an automatic stopping or pausing and an automatic restarting tends to increase (e.g., the time period t 3  is greater than the time period t 2  which is greater than the time period t 1 ). Once the tissue is deemed to be sufficiently compressed, the jaws of the surgical instrument  5500  can be locked into a closed or clamped position, the closing force F remains essentially constant and the firing motion can be initiated. 
     Although the example graph  5540  of  FIG.  108    was described in the context of various aspects of the surgical instrument  5500 , it will be appreciated that the respective illustrations and descriptions of the closing force F can vary for other aspects. For example, in various aspects of the surgical instrument  5500 , fewer than or more than three automatic stops or pauses may be required before the tissue is deemed to be sufficiently compressed. Similarly, fewer than or more than three automatic restarts may occur before the tissue is deemed to be sufficiently compressed. Also, although  FIG.  108    was described in the context of the closing force F over time t, it will be appreciated that in various aspects, a firing force (not shown) may also be measured/sampled over time. As described in more detail hereinbelow, the firing force measurements and parameters related thereto may be utilized by the control circuit to automatically change a firing motion based on a trigger, a threshold and/or an event. 
       FIG.  109    illustrates an example graph  5550  showing a curve  5552  representative of a firing force F over time t for various aspects of the surgical instrument  5500  and a curve  5554  representative of a knife velocity V over time t for various aspects of the surgical instrument  5500 . The firing force F is shown along an upper portion of the vertical axis, the knife velocity V is shown along a lower portion of the vertical axis and the time t is shown along the upper horizontal axis as well as along the lower horizontal axis. Stated differently, the curve  5552  is a representation of the firing force signal at various times during a firing motion and the curve  5554  is a representation of the knife velocity signal at various times during a firing motion. As shown in  FIG.  109   , the knife transitions over three distinct zones Z 1 , Z 2 , Z 3 . In zone Z 1 , the knife velocity V and force F are ramping up from a zero initial value. In zone Z 2 , the knife is traveling at a relatively constant velocity V and spikes in the measured force F are due to the staple driving force. In zone Z 3 , the knife velocity V and the force F are ramping down to zero. 
     The curves  5552 ,  5554  may be generated mathematically by the controller based on the firing force signal(s) and the knife velocity signal(s) received by the controller. The firing force F and the knife velocity V shown in the example graph  5550  of  FIG.  109    may be representative of a condition where the thickness and composition of the tissue along the cut line is uniform. The firing force F represented on the upper portion of the vertical axis may be a force experienced by the drive system of the surgical instrument (e.g., by the sled, the knife and/or the firing bar), and/or any combination thereof. The firing force F can be measured in any suitable manner, either directly or indirectly. For example, according to various aspects, the firing force F can be measured directly by a sensor (e.g. a strain gauge) positioned on the sled, on the knife, or indirectly by a current draw of the motor, and/or any combination thereof. The knife velocity V represented on the lower portion of the vertical axis may be a velocity of the knife, a velocity of the sled, a velocity of another component of the drive system (e.g., the firing bar), and/or any combination thereof. The knife velocity V can be measured in any suitable manner, either directly or indirectly. For example, according to various aspects, the knife velocity V can be measured directly by a combination of a magnet positioned on the firing bar and a Hall-effect sensor or indirectly by a current draw of the motor, an encoder coupled to the shaft of the motor, and/or any combination thereof. 
     As explained in more detail hereinbelow (See, e.g.,  FIG.  110   ), in various aspects the surgical instrument  5500  can measure and/or determine the following: an instantaneous firing force F, one or more peak values of the firing force F, one or more valley values of the firing force F, an average of the firing force F, a change of the firing force F over time t (i.e., a rate of change of the firing force F), a slope of a line connecting successive peak values of the firing force F, a slope of a line connecting successive valley values of the firing force F, a time between successive peak values of the firing force F, a time between successive valley values of the firing force F, a decrease of the firing force F from a peak value of the firing force F to a following valley value of the firing force F, an increase of the firing force F from a valley value of the firing force F to a following peak value of the firing force F, an instantaneous knife velocity V, one or more peak values of the knife velocity V, one or more valley values of knife velocity V, an average of the knife velocity V, a change of the knife velocity V over time t (i.e., a rate of change of the knife velocity V), and/or any combinations thereof. 
     For the example graph  5550  shown in  FIG.  109   , at time t=0 the firing force F is essentially zero, the knife is in the fully retracted position and the knife is stationary (the knife velocity V is zero). Once the firing motion is actuated, the knife begins to advance and initially advances at an increasing velocity. As the knife advances, the sled advances and the staples are driven from the staple cartridge, through the tissue and against the anvil. As the knife and sled advance and the knife velocity V increases, the firing force F increases and reaches a first peak value when a first row of staples is driven from the staple cartridge. At this point in time, the knife is not yet in contact with the tissue. For the example graph  5550  shown in  FIG.  109   , the first peak  5556  of the firing force F is indicative of the first row of staples being driven from the staple cartridge. According to various aspects, the first row of staples is not driven through the tissue and is thus not driven against the anvil. According to other aspects, the first row of staples is driven through a portion of the tissue which is thinner than the thickest portion of the tissue and against the anvil. According to yet other aspects, the first row of staples is driven through a portion of the tissue which was previously stapled (with staples from another staple cartridge), thereby resulting in that portion of the tissue being double stapled. 
     After the first row of staples is driven as described hereinabove, the firing force F decreases until a second row of staples is driven, which causes the firing force F to reach a second peak  5558 . At this point in time, the knife is not yet in contact with the tissue. For the example graph  5550  shown in  FIG.  109   , the second peak  5558  is indicative of the second row of staples being driven from the staple cartridge. According to various aspects, the second row of staples is not driven through the tissue and is thus not driven against the anvil. According to other aspects, the second row of staples is driven through a portion of the tissue which is thicker than the portion of tissue through which the first row staples was driven (but thinner than the thickest portion of the tissue) and against the anvil. According to yet other aspects, the second row of staples is driven through a portion of the tissue which was already stapled (with staples from another staple cartridge), thereby resulting in that portion of the tissue being double stapled. 
     After the second row of staples is driven as described hereinabove, the firing force F decreases until a third row of staples is driven, which causes the firing force F to reach a third peak  5560 . At this point in time, the knife is not yet in contact with the tissue. For the example graph  5550  shown in  FIG.  109   , the third peak  5560  is indicative of the third row of staples being driven from the staple cartridge. According to various aspects, the third row of staples is not driven through the tissue and is thus not driven against the anvil. According to other aspects, the third row of staples is driven through a portion of the tissue which is thicker than the portion of tissue through which the second row staples was driven (but thinner than the thickest portion of the tissue) and against the anvil. According to yet other aspects, the third row of staples is driven through a portion of the tissue which was already stapled (with staples from another staple cartridge), thereby resulting in that portion of the tissue being double stapled. 
     After the third row of staples is driven as described hereinabove, the firing force F decreases until a fourth row of staples is driven, which causes the firing force F to reach a fourth peak  5562 . At some point after the third row of staples is driven, the knife comes into contact with the tissue, begins severing the tissue and advances at a substantially constant velocity. For the example graph  5550  shown in  FIG.  109   , the fourth peak  5562  is indicative of the knife severing the tissue and the fourth row of staples being driven from the staple cartridge through the tissue and against the anvil. 
     After the fourth row of staples is driven as described hereinabove, the firing force F continues the cycle of decreasing and increasing as the knife advances through the tissue at a substantially constant velocity and additional rows of staples are driven through the tissue and against the anvil. For the aspects shown in  FIG.  109   , the knife velocity V is substantially constant from the time the knife comes in contact with the tissue (shortly before the fourth peak value of the firing force is reached) to a time shortly after the knife has severed through the tissue (the last peak value before the last three rows of staples are driven). Shortly after the knife has severed through the tissue, the knife velocity V begins to decrease from the substantially constant velocity to zero. The decrease in the knife velocity V and the lower forces required to drive the last three rows of staples produces lower and lower peak values of the firing force F. There are a number of different reasons why lower forces are required to drive the last three rows of staples. For example, according to various aspects, the last three rows of staples may extend past the tissue (and thus are not driven through the tissue and against the anvil), the last three rows of staples may be driven through a less compressed portion of the tissue (due to the geometry of the anvil and the elongated channel), the last three rows of staples may be driven through a thinner portion of the tissue, and/or any combination thereof. Once all of the staples have been driven and the knife velocity V has reached zero (the knife has stopped advancing), the firing force F is zero. 
     Although the example graph  5550  of  FIG.  109    was described in the context of various aspects of the surgical instrument  5500 , it will be appreciated that the respective illustrations and descriptions of the firing force F and the knife velocity V can vary for other aspects. For example, in various aspects of the surgical instrument  5500 , the knife may come into contact with the tissue after fewer than or more than three rows of staples have been driven from the staple cartridge. Similarly, fewer than or more than three rows of staples may be driven after the knife has severed through the tissue. 
       FIG.  110    illustrates an example graph  5570  showing a curve  5572  representative of a firing force F and a knife position X over time t for various aspects of the surgical instrument  5500 . The firing force F is shown along the vertical axis and the knife position X and the time t are shown along the horizontal axis. As shown along the horizontal axis, the knife position X travels over five Zones 1-5 along the knife channel in the cartridge  304  located in the lower jaw  302  of the end effector  300  of the surgical instrument  5500 , as described in more detail hereinbelow. In summary, Zone 1 is a tissue free zone where the knife moves without contacting tissue until it initially contacts tissue in Zone 2. The knife then transects the tissue as it travels along Zone 3. The knife transitions out of the tissue in Zone 4 and in stops in Zone 5, where the knife reaches the end of its travel span in a tissue free region. The spikes  5574  in the various sections 1-5 are due the additional force required to drive staples through the tissue located in the jaws  306 ,  302  of the end effector  300  portion of the surgical instrument  5500 . 
     Accordingly, the curve  5572  is a representation of the firing force signal at various times during a firing motion in combination with the staple driving force, collectively referred to herein a the driving force F. The curve  5572  may be generated mathematically by the controller based on the firing force signal(s) received by the controller. The firing force F and the knife position X force shown in the example graph  5570  may be representative of a condition where the thickness and composition of the tissue along the cut line is uniform. The firing force F represented on the vertical axis may be a force experienced by the drive system of the surgical instrument  5500  (e.g., by the sled, the knife, and/or the firing bar), and/or any combination thereof. The firing force F can be measured in any suitable manner, either directly or indirectly. For example, according to various aspects, the firing force F can be measured directly by a sensor (e.g., a strain gauge) positioned on the sled, on the knife, or indirectly by a current draw of the motor, and/or any combination thereof. 
     According to various aspects, the operation of the surgical instrument  5500  may be controlled by monitoring the amplitude of the firing force signal and the knife position X, and changing the firing motion when the amplitude of the firing force signal reaches or exceeds a predetermined threshold. As previously described, this process may be controlled with an algorithm such as the method  1010  of controlling a closing motion of the surgical instrument  5500  according to various aspects illustrated in  FIG.  107   . According to some aspects, the changing of the firing motion only proceeds when the knife position is within a predetermined range of positions. With reference to  FIG.  110   , for example, firing force amplitude Fcrit may be determined to be an excessive amount of the firing force F experienced by the surgical instrument  5500 . Upon the occurrence of the amplitude of the firing force signal reaching or exceeding the firing force amplitude Fcrit, an algorithm may operate to change the firing motion by slowing down, pausing or stopping the rotation of the motor(s) which drive the knife of the surgical instrument  5500  to prevent the surgical instrument  5500  from experiencing excessive forces. 
     The curve  5572  provides a useful representation of how the firing force F and the knife position X vary over time t. The change in the firing force F over time t (i.e., the rate of change of the closing force F) may provide useful feedback to the control circuit to control the firing mechanism of the surgical instrument  5500 . The change in the firing force F over time t may be represented as a derivative of the curve  5572  and may be approximated over short periods of time by the equation Slope S=ΔF/Δt, where ΔF is the change of the firing force F and Δt is the change of the time t. The slope can have a positive value or a negative value. The slope represented by ΔF 1 /Δt 1  of the curve  5572  has a positive value and the slope represented by ΔF 2 /Δt 2  of the curve  5572  has a negative value. The curve  5572  is representative of an analog signal over time which is sampled and converted to a digital value by an A/D converter as the firing mechanism is advanced/retracted. Once the analog signal is digitized, the control circuit may thereafter determine the slope of the firing force signal represented by the curve  5542  at any point during the firing motion. 
     According to various aspects, the operation of the surgical instrument  5500  may be controlled by monitoring the slope of the curve  5572  (the slope of the firing force signal) and the knife position X, and changing the firing motion based on the value of the slope. According to some aspects, the changing of the firing motion only proceeds when the knife position is within a predetermined range of positions. In general, with reference to  FIG.  110   , the slope of the curve  5572  may be approximated by the equation S=ΔF/Δt, where ΔF is the change of the firing force F and Δt is the change of the time t. Those skilled in the art will appreciate that the instantaneous slope may be calculated by taking the derivative of the curve  5572 . Over time t, the slope S may be monitored by the control circuit and utilized by the control circuit to control the operation of the surgical instrument  5500 . For example, an algorithm of the surgical instrument  5500  may be configured to monitor the change of the firing force F over the time t, stop or pause the firing motion when the slope of the curve  5572  reaches or exceeds a first predetermined threshold, then restart the firing motion when the slope of the curve  5572  reaches or falls below a second predetermined threshold. The value of the slope represented by ΔF 1 /Δt 1  (a positive value) shown in  FIG.  110    may be determined by the controller and may represent the first predetermined threshold. Similarly, the value of the slope represented by ΔF 2 /Δt 2  (a negative value) shown in  FIG.  110    may be determined by the controller and may represent the second predetermined threshold. Thus, according to various aspects, the algorithm can control the operation of the control circuit based on the determined slope, whether instantaneous or approximated. 
     According to various aspects, the operation of the surgical instrument  5500  may be controlled by monitoring a parameter related to the firing force signal and the knife position X, and changing the firing motion based on the value of the parameter. According to some aspects, the changing of the firing motion only proceeds when the knife position is within a predetermined range of positions. With reference to  FIG.  110   , for example, an algorithm of the surgical instrument  5500  may be configured to monitor first and second parameters (e.g., the slope of a line connecting successive peak values of the firing force signal represented by ΔF 3 /Δt 3  and the slope of a line connecting successive valley values of the firing force signal represented by ΔF 4 /Δt 4  in  FIG.  110   ), stop or pause the firing motion when the value of the first parameter reaches or exceeds a first predetermined threshold, then restart the firing motion when the value of the second parameter reaches or falls below a second predetermined threshold. The value of the slope represented by ΔF 3 /Δt 3  (a positive value) shown in  FIG.  110    may be determined by the controller and may represent the first predetermined threshold. Similarly, the value of the slope represented by ΔF 4 /Δt 4  (a negative value) shown in  FIG.  110    may be determined by the controller and may represent the second predetermined threshold. Thus, according to various aspects, the algorithm, such as the method  1010  of controlling a closing motion of the surgical instrument  5500  according to various aspects shown in  FIG.  107   , can control the operation of the control circuit based on the determined slopes, whether instantaneous or approximated. 
     Alternatively, the controller may determine values for other parameters related to the firing force signal and utilize the values of the parameters to change the firing motion. According to some aspects, the changing of the firing motion only proceeds when the knife position is within a predetermined range of positions. With regard to  FIG.  110   , the other parameters may include, for example, a duration between successive peak values of the firing force signal represented by the time period A shown in  FIG.  110   , a duration between successive valley values of the firing force signal represented by the time period B shown in  FIG.  110   , a decrease in the amplitude of the firing force signal from a peak value to a following valley value as represented by the magnitude C shown in  FIG.  110    and an increase in the firing force signal from a valley value to a following peak value represented by the magnitude D shown in  FIG.  110   . The above-described parameters/values determined by the control circuit can be utilized with or without the knife position X to automatically control the firing motion of the surgical instrument  5500 . Additionally, the above-described parameters/values determined by the control circuit can be utilized within a limited time/rate window in combination with surgeon variable rate actuation control and feedback. 
     For the example graph  5570  shown in  FIG.  110   , at time t=0 the knife is in a fully retracted position near the proximal end of the end effector and over time advances to a fully advanced position near the distal end of the end effector. The overall distance the knife moves from the fully retracted position to the fully advanced position during a firing motion can be divided into predefined zones, with each predefined zone representative of a different operating condition of the surgical instrument  5500 . For example, according to various aspects, the overall distance the knife moves from the fully retracted position to the fully advanced position during a firing motion can be divided into five predefined zones and the five zones may be representative of the following: Zone 1 is representative of the knife advancing from a fully retracted position at an increasing velocity but not yet being in contact with tissue positioned between the jaws of the surgical instrument; Zone 2 is representative of the knife advancing at a more rapidly increasing velocity and staples being driven into the tissue (but not into the thickest portion of the tissue); Zone 3 is representative of the knife reaching a maximum or peak velocity, then continuing to advance at a substantially constant velocity and staples being driven into the thickest portion of the tissue; Zone 4 is representative of the knife continuing to advance at a substantial constant velocity, then decreasing in velocity after the tissue has been severed and staples still being driven into the thickest portion of the tissue; and Zone 5 is representative of the knife having reached its fully advanced position (the knife has stopped) and all of the staples have been fired. 
     Although five zones are shown in  FIG.  110   , it will be appreciated that the overall distance the knife moves from the fully retracted position to the fully advanced position during a firing motion can be divided into more than or less than five zones, and the respective zones can be representative of operating conditions different from those described hereinabove. 
     In practice, the thickness and composition of the tissue can vary along the cut line. Thus, it will be appreciated that there are many conditions which can cause the firing force F, the knife velocity V and/or the knife position X to deviate from the firing force F, the knife velocity V and/or the knife position X shown in  FIGS.  103  and  104   . 
       FIG.  111    illustrates an example graph  5580  showing a curve  5582  representative of a firing force F over time t for various aspects of the surgical instrument  5500  and a curve  5584  representative of a knife velocity V over time t for various aspects of the surgical instrument  5500 . Stated differently, the curve  5582  is a representation of the firing force signal at various times during a firing motion and the curve  5584  is a representation of the knife velocity signal at various times during a firing motion. The curves  5582 ,  5584  may be generated mathematically by the controller based on the firing force signal(s) and the knife velocity signal(s) received by the controller. The firing force F is shown along an upper portion of the vertical axis, the knife velocity V is shown along a lower portion of the vertical axis and the time t is shown along the upper horizontal axis as well as along the lower horizontal axis. The firing force F represented on the upper portion of the vertical axis may be a force experienced by the drive system of the surgical instrument  5500  (e.g., by the sled, the knife and/or the firing bar), and/or any combination thereof. The firing force F can be measured in any suitable manner, either directly or indirectly. For example, according to various aspects, the firing force F can be measured directly by a sensor (e.g., a strain gauge) positioned on the sled, on the knife, or indirectly by a current draw of the motor, and/or any combination thereof. 
     The knife velocity V represented on the lower portion of the vertical axis may be a velocity of the knife, a velocity of the sled, a velocity of another component of the drive system (e.g., the firing bar), and/or any combination thereof. The knife velocity V can be measured in any suitable manner, either directly or indirectly. For example, according to various aspects, the knife velocity V can be measured directly by a combination of a magnet positioned on the firing bar and a Hall-effect sensor or indirectly by a current draw of the motor, an encoder coupled to the shaft of the motor, and/or any combination thereof. 
     In addition to the firing force F and the knife velocity V being measured, the firing force measurements (including the parameters/values derived therefrom) and the knife velocity measurements can be stored by a memory of the surgical instrument  5500 . An algorithm of the control circuit of the surgical instrument  5500  can utilize the stored measurements to provide automated control of the surgical instrument  5500 . For example, according to various aspects, the algorithm can automatically stop or pause a further advancement of the knife based on a trigger, a threshold and/or an event. For example, when a slope of a line connecting successive peak values of the firing force signal (e.g., the slope of the line A shown in  FIG.  111   ) reaches or exceeds a predetermined threshold (e.g., the slope of the line A is greater than the predetermined threshold), the algorithm can automatically stop or pause a further advancement of the knife. 
     According to other aspects, the algorithm can automatically stop or pause a further advancement of the knife when a slope of a line connecting successive peak values of the firing force signal and the amplitude of the firing force signal reaches or exceeds a second predetermined threshold (e.g., the amplitude is greater than the firing force amplitude F 1 ). According to yet other aspects, the algorithm can automatically stop or pause a further advancement of the knife when the a slope of a line connecting successive peak values of the firing force signal reaches or exceeds a predetermined threshold, the amplitude of the firing force signal reaches or exceeds a second predetermined threshold and the position of the knife is within a predefined zone of operation (e.g., a position where the knife is advancing at a substantially constant velocity). For these aspects, when the combinations are met, the controller signals the motor controller to change the firing motion by slowing down, pausing or stopping the rotation of the motor(s) which drive the knife of the surgical instrument  5500  to prevent the surgical instrument  5500  from experiencing excessive forces. For the example graph  5580  shown in  FIG.  111   , when the combinations are met, the controller communicates a pause signal or a stop signal to the motor controller to change the firing motion by pausing or stopping the rotation of the motor(s) which drive the knife velocity and the knife velocity is reduced from the substantially constant velocity to zero. 
     After the advancement of the knife has been stopped or paused, the algorithm may automatically restart the advancement of the knife based on a trigger, a threshold and/or an event. For example, according to various aspects, the algorithm can automatically restart the advancement of the knife when a slope of the curve  5582  (e.g., the slope ΔF/Δt shown in  FIG.  111   ) reaches or falls below a predetermined threshold. The predetermined threshold may be indicative of a stabilized tissue condition. According to other aspects, when a predetermined period of time has passed since the advancement of the knife was stopped or paused (e.g., the period of time between t 1  and t 2  in  FIG.  111   ), the algorithm may automatically restart a further advancement of the knife. The predetermined period of time may be considered an adequate amount of time for an adequate amount of tissue creep to occur and/or for the tissue to reach a stabilized condition. 
     According to yet other aspects, when the amplitude of the firing force signal drops a predetermined amount from what the amplitude of the firing force signal was at the time of the initiation of the stop or pause, the algorithm may automatically restart a further advancement of the knife. The predetermined amount of the drop in the amplitude of the firing force signal may be a quantitative amount (e.g., the difference between the firing force amplitude F 1  and the firing force amplitude F 2  in  FIG.  111   ) or a percentage (e.g., a 10% drop). The predetermined amount of the drop in firing force signal may be considered sufficient enough for an adequate amount of tissue creep to have occurred and/or for the tissue to have reached a stabilized condition. 
     According to yet other aspects, when the amplitude of the firing force signal drops to a predetermined value (e.g., the firing force amplitude F 2  shown in  FIG.  111   ), the algorithm may automatically restart a further advancement of the knife. The predetermined value of the firing force F may be considered low enough for an adequate amount of tissue creep to have occurred and/or for the tissue to have reached a stabilized condition. Regardless of what the restarting of the knife is based on, when the trigger, threshold and/or event occurs, the controller communicates a start signal to the motor controller to restart the firing motion by restarting the rotation of the motor(s) which drive the knife of the surgical instrument  5500 , and the restarting of the rotation of the motor(s) causes the knife velocity V to increase from zero to a substantially constant velocity. 
     After the knife has severed through the tissue, the knife velocity V begins to decrease from the substantially constant velocity to zero. The decrease in the knife velocity V and the lower firing force F required to drive the last few rows of staples produces lower and lower peak values of the firing force signal. Once all of the staples have been driven and the knife velocity V has reached zero (the knife has stopped advancing), the firing force F is zero. 
     Although the knife position X is not shown in  FIG.  111   , it will be appreciated that according to some aspects the changing of the firing motion only proceeds when the knife position is within a predetermined range of positions. 
       FIG.  112    illustrates an example graph  5690  showing a curve  5692  representative of a closing force FC over time t for various aspects of the surgical instrument  5500  and a curve  5694  representative of a firing force FF over time t for various aspects of the surgical instrument  5500 . The closing force FC is shown along the “left” vertical axis, the firing force FF is shown along the “right” vertical axis and the time t is shown along the horizontal axis. When viewed together the curves  5692 ,  5694  reflect the timing of the closing motion and the firing motion relative to one another, where the closing motion is initiated prior to the initiation of the firing motion. Although the example graph  5690  shows a threshold force Fcrit as being the same amplitude for both the closing force FC and the firing force FF, it will be appreciated that the amplitude of the threshold force Fcrit for the closing force FC may be different from the amplitude of the threshold force Fcrit for the firing force FF. Stated differently, the scale of the “left” vertical axis can be different from the scale of the “right” vertical axis. 
     The curve  5692  is a graphical representation of the closing force signal at various times during a closing motion and may be similar or identical to the curve  5542  of FOG.  108 . Thus, as set forth hereinabove, the curve  5692  may be generated mathematically by the controller based on the closing force signal(s) received by the controller. The closing force FC represented on the “left” vertical axis may be a force experienced by tissue clamped between the jaws of the surgical instrument  5500 , a force experienced by the jaws of the surgical instrument  5500  (e.g., by the anvil and/or the elongated channel), a force experienced by the closure tube of the surgical instrument  5500 , and/or any combinations thereof. The closing force FC can be measured in any suitable manner, either directly or indirectly. For example, according to various aspects, the closing force FC can be measured directly by a sensor (e.g., a strain gauge) positioned on the anvil, on the elongated channel, on the closure tube, or indirectly by an impedance of the tissue, a current draw of the motor, and/or any combinations thereof. 
     The curve  5694  is a graphical representation of the firing force signal at various times during a firing motion. The curve  5694  may be generated mathematically by the controller based on the firing force signal(s) received by the controller. The firing force FF represented on the “right” vertical axis may be a force experienced by the drive system of the surgical instrument  5500  (e.g., by the sled, the knife, and/or the firing bar), and/or any combination thereof. The firing force FF can be measured in any suitable manner, either directly or indirectly. For example, according to various aspects, the firing force FF can be measured directly by a sensor (e.g., a strain gauge) positioned on the sled, on the knife, or indirectly by a current draw of the motor, and/or any combination thereof. Although not shown for purposes of simplicity, the respective zones of the firing cycle (e.g., zones 1-5 as described hereinabove) could also be shown along the horizontal axis. 
     For the example graph  5690  in  FIG.  112   , at some time after the closing motion has commenced, the knife is still in the fully-retracted position and the firing force FF is approximately zero. As the knife and sled advance and the velocity of the knife increases, the firing force FF increases and reaches a first peak value  5696  when a first row of staples is driven from the staple cartridge. After the first row of staples is driven as described hereinabove, the firing force FF decreases until a second row of staples is driven, which causes the firing force FF to reach a second peak value  5698 . 
     At a later point in the firing motion, the slope of the firing force signal reaches or exceeds a predetermined threshold (this condition is shown as the slope A of the firing force signal in  FIG.  112   ) and the amplitude of the firing force FF reaches or exceeds a predetermined amplitude threshold (e.g., the amplitude Fcrit shown in  FIG.  112   ). In response, the control algorithm acts to slow down, stop or pause the further advancement of the knife and the firing force FF begins to decrease. 
     For the example graph  5690 , the slowing down, stopping or pausing of the knife continues until the firing force FF reaches a value which is 10% less than the predetermined amplitude threshold (e.g., Fcrit), at which point the further advancement of the knife is commenced. Of course, according to various aspects, the further advancement of the knife can be commenced when the firing force FF reaches a value which is less than or more than the 10% example shown in  FIG.  112   . The above-described automatic stopping or pausing and automatic restarting may be repeated any number of times. For the example graph  5690 , once the further advancement of the knife is commenced, the knife advances towards its fully advanced position and the firing force FF eventually decreases to zero as indicated at the far right side. 
       FIGS.  113 ,  114    illustrate various aspects of a direction sensor  5590  of the surgical instrument  5500 . According to various aspects, the control circuit of the surgical instrument  5500  may be configured to stop an advancement of the knife when a staple cartridge is not positioned or properly positioned in the elongated channel. For such aspects, the control circuit may include the direction sensor  5590 , a main processor and a safety processor, each positioned in the shaft assembly, as described above in connection with  FIGS.  16 A- 17 B . The direction sensor  5590  is electrically connected to the main processor and/or the safety processor of the shaft assembly. The main processor and/or the safety processor of the shaft assembly may be electrically connected to the main processor and/or the safety processor of the handle assembly. The direction sensor  5590  is positioned at a location relative to a starting point of the tissue transection, and is configured to sense movement of the firing bar and output a signal (e.g., a voltage) related to the sensed position of the firing bar to the main processor and/or safety processor of the shaft assembly. Based on the sensed movement of the firing bar, the main processor and/or the safety processor of the shaft assembly can determine and track a status of the movement and the direction of the movement of the firing bar as the firing bar moves distally and proximally of the starting point of the tissue transection. The main processor and/or the safety processor of the shaft assembly can signal the motor controller to power, cycle and/or reboot the electric motor to control the movement and the direction of the movement of the firing bar, and thus the movement and the direction of the movement of the knife, all while continuing to determine the relevant position of the firing bar based on the output signal of the direction sensor  5590 . 
     As shown in  FIGS.  113 ,  114   , the direction sensor  5590  includes first and second sensors  5592 ,  5594 , first and second transistors  5596 ,  5598 , an operational amplifier  5600  and a resistive element  5602 . The first and second sensors  5592 ,  5594  may be Hall-effect sensors, with each of the first and second Hall-effect sensors being positioned a set distance from the tissue transection or cut line. Collectively, the first and second transistors  5596 ,  5598 , the operational amplifier  5600  and the resistive element  5602  comprise a latching circuit, where the latching circuit outputs only the voltage related to the last Hall-effect sensor that was activated. 
       FIG.  113    indicates a firing stroke in which the magnet  5604  moves from an initial proximal position to a distal position. In  FIG.  113   , the magnet  5604  is shown in the final distal position and the output of the operational amplifier  5600  indicates the distal position of the magnet  5604 . In operation, as the firing bar moves distally from a proximal starting point of the tissue transection as shown in  FIG.  113   , a magnet  5604  positioned on the firing bar moves past the first Hall-effect sensor  5594  then past the second Hall-effect sensor  5592 . As the magnet  5604  moves past the first Hall-effect sensor  5594 , the first Hall-effect sensor  5594  outputs a signal which is indicative of the movement of the firing bar to a gate of the first transistor  5598  to drive the latching circuit to a first stable state Vcc. As the magnet  5604  moves past the second Hall-effect sensor  5592 , the second Hall-effect sensor  5592  outputs a signal which is indicative of the movement of the firing bar to a gate of the second transistor  5596  to drive the latching circuit to a second stable state 0.0 V. The latching circuit outputs a signal (e.g., a voltage 0.0 V) indicative of the second stable state to the main processor and/or the safety processor of the shaft assembly indicating that the firing bar is in the distal fired position. 
       FIG.  114    indicates a retracting stroke in which the magnet  5604  moves from an initial distal position to a final proximal position. In  FIG.  114   , the magnet  5604  is shown in the final proximal position and the output of the operational amplifier  5600  indicates the proximal position of the magnet  5604 . In operation, as the firing bar moves proximally toward the starting point of the tissue transection as shown in  FIG.  114   , the magnet  5604  positioned on the firing bar moves past the second Hall-effect sensor  5592  then past the first Hall-effect sensor  5594 . As the magnet  5604  moves past the second Hall-effect sensor  5592 , the second Hall-effect sensor  5592  outputs a signal which is indicative of the movement of the firing bar to the gate of the second transistor  5596  to drive the latching circuit to the second stable state of 0.0 V. As the magnet  5604  moves past the first Hall-effect sensor  5594 , the first Hall-effect sensor  5594  outputs a signal which is indicative of the movement of the firing bar to the gate of the first transistor  5598  to drive the latching circuit to the first stable state Vcc. The latching circuit outputs a signal (e.g., a voltage of Vcc) indicative of the first stable state to the main processor and/or the safety processor of the shaft assembly indicating that the firing bar is in the proximal retracted position. 
       FIG.  115    illustrates a perspective view of a surgical instrument  5700  in accordance with one or more aspects described herein. The surgical instrument  5700  is similar to the surgical instrument  5500  and includes an elongated channel configured to support a staple cartridge, an anvil pivotably connected to the elongated channel, a closure member mechanically coupled to the anvil, a knife mechanically coupled to the staple cartridge, an electric motor mechanically coupled to the closure member and/or the knife, a motor controller electrically coupled to the motor, and a control circuit electrically coupled to the motor controller. The surgical instrument  5700  is also similar to the surgical instrument  5500  in that the surgical instrument  5700  also includes sensors which are collectively configured to sense or measure a closing force, a firing force, a current drawn by the electric motor, an impedance of tissue positioned between the elongated channel and the anvil, a position of the anvil relative to the elongated channel, a position of the knife, or any combination thereof. The surgical instrument  5700  is also similar to the surgical instrument  5500  in that the surgical instrument  5700  also includes algorithms such as closing algorithms, firing algorithms, motor control algorithms, or any combination thereof, which operate to dynamically adjust the operation of the surgical instrument  5700 . However, the surgical instrument  5700  is different from the surgical instrument  5500  in that the surgical instrument  5700  further includes one or more additional algorithms (in addition to those described hereinabove) which provide additional control functionality for the surgical instrument  5700 , as described hereinbelow. 
     In certain situations, it may be desirable for the surgical instrument  5700  to ignore the occurrence of one or more of the above-described triggers, thresholds and/or events associated with the firing force. In accordance with one or more aspects, the surgical instrument  5700  includes one or more control algorithms which are configured to ignore certain triggers, thresholds and/or events if the triggers, thresholds and/or events occur before an amplitude of the firing force has reached or exceeded a predetermined threshold, if the triggers, thresholds and/or events occur within certain zones of the firing motion, and combinations thereof. As described hereinabove, the zones of the firing motion are related to the position of the knife. In other words, the control algorithms can vary the firing force triggers, thresholds and/or events (e.g., values of the thresholds) based on the position of the knife within the firing motion. 
       FIG.  116    illustrates a method  5710  of controlling a firing motion of the surgical instrument  5700  in accordance with one or more aspects. The process starts when a firing motion is initiated  5712 . The closing motion may be initiated, for example, by pulling a firing trigger toward a handle A sensor resident with the surgical instrument  5700  senses/measures  5714  a firing force. The firing force may be, for example, a force experienced by the drive system of the surgical instrument (e.g., by the sled, the knife and/or the firing bar), and/or any combination thereof. The firing force F can be measured in any suitable manner, either directly or indirectly. For example, in accordance with one or more aspects, the firing force F can be measured directly by a sensor (e.g. a strain gauge) positioned on the sled, on the knife, or indirectly by a current draw of the motor. 
     In response to the firing force, the sensor outputs  5716  a firing force signal, which is indicative of the firing force sensed/measured  5714  by the sensor. Depending on the configuration of the sensor, the firing force signal can be an analog signal or a digital signal. Upon determining  5718  whether the firing force signal is either an analog signal or a digital signal, the process proceeds along the corresponding branch. When the determination  5718  is that the firing force signal is an analog signal, the process proceeds along the analog branch, where the analog signal is received by an A/D converter, converted  5720  to a digital signal representative of the analog signal by the A/D converter and the digital signal is output by the A/D converter. When the determination  5718  is that the firing force signal is a digital signal, the process proceeds along the digital branch because there is no need for an A/D conversion  5720  when the firing force signal is a digital signal. 
     The firing force signal which is a digital signal representative of the firing force sensed/measured  5714  by the sensor is received by a controller. The controller utilizes the digital signal and determines  5722  whether the firing force sensed/measured  5714  by the sensor reaches or exceeds a predetermined threshold. The controller may make this determination  5722  based on a comparison of a magnitude of the firing force sensed/measured  5714  by the sensor and the predetermined threshold, based on a comparison of an amplitude of the firing force signal output  5716  by the sensor and a predetermined threshold, or any combination thereof. 
     When the controller determines  5722  that the firing force sensed/measured  5714  by the sensor has not reached or exceeded the predetermined threshold, the firing motion originally initiated  5712  is continued  5724  along with interim processes  5714 - 5722 . When the controller determines  5722  that the firing force sensed/measured  5714  by the sensor has reached or exceeded the predetermined threshold, the controller then determines  5726  whether or not to ignore the fact that the firing force has reached or exceeded the predetermined threshold. This determination  5726  can be based, for example, on whether or not the amplitude of the firing force signal has reached or exceeded a predetermined threshold, based on the position of the sled, the knife and/or the firing bar, or any combinations thereof. For example, as described in more detail hereinbelow, in certain aspects the controller may determine  5726  to ignore the fact that the slope of the firing force signal has reached or exceeded a predetermined slope threshold if the amplitude of the firing force signal has not yet reached or exceeded a predetermined amplitude threshold. In other aspects, the controller may determine  5726  to ignore the fact that the slope of the firing force signal has reached or exceeded a predetermined slope threshold based on the position of the sled, the knife, the firing bar, or any combination thereof when the knife is in a certain zone (e.g., Zone 1 or Zone 5) of the firing motion. For instances when the controller determines  5726  to ignore the fact that a parameter of the firing force signal has reached or exceeded a predetermined threshold, the firing motion originally initiated  5712  is continued  5724  along with interim processes  5714 - 5722 . 
     In other aspects, the controller may determine  5726  not to ignore the fact that a parameter of the firing force signal has reached or exceeded a predetermined threshold. The determination  5726  not to ignore the fact that a parameter of the firing force signal has reached or exceeded the predetermined threshold can be based, for example, on whether or not the amplitude of the firing force signal has reached or exceeded a predetermined threshold, based on the position of the sled, the knife and/or the firing bar, or any combinations thereof. For instances when the controller determines  5726  not to ignore the fact that a parameter of the firing force signal has reached or exceeded the predetermined threshold the controller changes  5730  the firing motion. According to some aspects, the controller may change the firing motion by modifying or adjusting a firing algorithm being executed by the controller to cause the firing motion to be slowed down, paused or stopped to prevent the surgical instrument  5700  from experiencing excessive forces. According to other aspects, the controller may change the firing motion by executing a different firing algorithm which causes the firing motion to be slowed down, paused or stopped to prevent the surgical instrument  5700  from experiencing excessive forces. In either case, the firing motion may be slowed down, stopped or paused by having the controller communicate a slow down signal, a stop signal or a pause signal to the motor controller to slow down, stop or pause the rotation of the motor(s) which drive the sled, knife, firing bar or any combination thereof of the surgical instrument  5700 . 
     Upon changing the firing motion  5728 , when the change of the firing motion  5728  is a slowing down of the firing motion (a slowing down of the rotation of the motor(s) which drive the sled, knife and/or firing bar), the process continues  5730  the closing motion originally initiated  5712  but at a reduced speed and the interim process  5714 - 5726  is continued but the firing of the sled, knife and/or firing bar occurs at a reduced speed. When the change of the firing motion  5728  is a stopping or pausing of the firing motion (a stopping or pausing of the rotation of the motor(s) which drive the sled, knife and/or firing bar), the process suspends or terminates  5732  the firing motion. 
     In accordance with one or more aspects, the operation of the surgical instrument  5700  may be controlled by monitoring parameters of the firing force signal (e.g., the amplitude, the slope, etc.) and in cases where a predetermined threshold is reached or exceeded, deciding whether change the firing motion based on the monitored parameters or to ignore the reaching or exceeding of the predetermined threshold. For example, in accordance with one or more aspects, if the change of the firing force F over time t (e.g., the slope of the firing force signal) reaches or exceeds a predetermined threshold before the firing force F reaches or exceeds a first firing force threshold, the control algorithm may ignore the fact that the slope of the firing force signal reached or exceeded the predetermined threshold and allow the operation of the surgical instrument  5700  to proceed as if the slope of the firing force signal had never reached or exceed the predetermined threshold. 
       FIG.  117    illustrates an example graph  5740  showing a curve  5742  representative of a firing force F over time t for various aspects of the surgical instrument  5700 . The firing force F is shown along the vertical axis and the time t is shown along the horizontal axis. Stated differently, the curve  5742  is a graphical representation of the firing force signal at various times during a firing motion. The curve  5742  may be generated mathematically by the controller based on the firing force signal(s) received by the controller. The firing force F shown in the example graph  5740  may be representative of a condition where the thickness and composition of the tissue along the cut line is uniform. The firing force F represented on the vertical axis may be a force experienced by the drive system of the surgical instrument  1000  (e.g., by the sled, the knife, and/or the firing bar), and/or any combination thereof. The firing force F can be measured in any suitable manner, either directly or indirectly. For example, in accordance with one or more aspects, the firing force F can be measured directly by a sensor (e.g., a strain gauge) positioned on the sled, on the knife, or indirectly by a current draw of the motor, and/or any combination thereof. 
     For the example graph  5740  shown in  FIG.  117   , at time t=0, the knife is in a fully retracted position near the proximal end of the end effector and over time advances to a fully advanced position near the distal end of the end effector. As described hereinabove, the overall distance the knife moves from the fully retracted position to the fully advanced position during a firing motion can be divided into predefined zones, with each zone being representative of a different operating condition of the surgical instrument  5700 . Although not shown in  FIG.  117    for purposes of simplicity, the respective zones of the firing motion (e.g., zones 1-5 as described hereinabove) could also be shown along the horizontal axis of  FIG.  117   . 
     Shortly after the knife moves from its fully retracted position towards its fully advanced position, the change of the firing force F over time t reaches or exceeds a predetermined slope threshold (this condition is shown as the slope A of the firing force signal in  FIG.  117   ). As the slope A occurs in this example prior to the firing force F reaching or exceeding a first firing force threshold (shown as F 1  in  FIG.  117   ), the control algorithm may ignore the fact that the slope A reached or exceeded the predetermined threshold and allow the operation of the surgical instrument  5700  to proceed as if the slope A had never reached or exceed the predetermined threshold. Similarly, the control algorithm could also ignore the Slope A trigger, threshold or event based on the position of the knife (e.g., if the knife was in zone 2 of the firing motion when the predetermined slope threshold was reached or exceeded). 
     Due to the slope A trigger, threshold and/or event effectively being ignored, the knife continues to advance toward the fully advanced position and the firing force F continues to rise over time t. As shown in  FIG.  117   , the slope of the firing force signal again reaches or exceeds the predetermined slope threshold (this instance is shown as the slope A1 of the firing force signal in  FIG.  117   ). In accordance with one or more aspects, the reaching or exceeding of the predetermined slope threshold alone is sufficient for the control algorithm to change the firing motion to slow down, stop or pause the further advancement of the knife. According to other aspects, the reaching or exceeding of the predetermined amplitude threshold (e.g., the amplitude Fcrit shown in  FIG.  117   ) alone is sufficient for the control algorithm to change the firing motion to slow down, stop or pause the further advancement of the knife. According to yet other aspects, the combination of the reaching or exceeding of the predetermined slope threshold and the reaching or exceeding of the predetermined amplitude threshold causes the control algorithm to change the firing motion to slow down, stop or pause the further advancement of the knife. As shown in  FIG.  117   , when the slope A1 of the firing force signal reaches or exceeds the predetermined slope threshold and the amplitude of the firing force signal reaches or exceeds the predetermined amplitude threshold (e.g., Fcrit), the control algorithm changes the firing motion to slow down, stop or pause the further advancement of the knife and the firing force F begins to decrease. 
     The slowing down, stopping or pausing of the knife continues until the firing force F reaches a value which is 10% less than the predetermined amplitude threshold (e.g., Fcrit), at which point the further advancement of the knife is commenced. Of course, in accordance with one or more aspects, the further advancement of the knife can be commenced when the firing force reaches a value which is less than or more than the 10% example shown in  FIG.  117   . For the example graph  5742 , once the further advancement of the knife is commenced, the knife advances to its fully advanced position and the firing force decreases to zero as indicated at the far right side of  FIG.  117   . 
     According to other aspects, the decision to change the firing motion or to ignore the reaching or exceeding of the predetermined threshold may be further based on the position of the sled, knife, firing bar or combinations thereof. For example, in accordance with one or more aspects, if the change of the firing force over time t reaches or exceeds a predetermined threshold while the knife is within a certain zone of the firing motion (e.g., zone 2 or zone 4), the control algorithm may ignore the fact that the slope of the firing force signal reached or exceeded the predetermined threshold and allow the operation of the surgical instrument  5700  to proceed as if the slope of the firing force signal had never reached or exceed the predetermined threshold. 
       FIG.  118    illustrates an example graph  5750  showing a curve  5752  representative of a firing force F over time t for various aspects of the surgical instrument  5700 . The curve  5752  may be generated mathematically by the controller based on the firing force signal(s) received by the controller. The firing force F shown in the example graph  5750  may be representative of a condition where the thickness and composition of the tissue along the cut line is uniform. The firing force F represented on the vertical axis may be a force experienced by the drive system of the surgical instrument  5700  (e.g., by the sled, the knife, and/or the firing bar), and/or any combination thereof. Although not shown for purposes of simplicity, the respective zones of the firing cycle (e.g., zones 1-5 as described hereinabove) could also be shown along the horizontal axis. 
     The firing force F can be measured in any suitable manner, either directly or indirectly. For example, in accordance with one or more aspects, the firing force F can be measured directly by a sensor (e.g., a strain gauge) positioned on the sled, on the knife, or indirectly by a current draw of the motor, and/or any combination thereof. 
     For the example graph  5750  in  FIG.  118   , at time t=0 the knife is in the fully-retracted position and the firing force F is zero. As the knife and sled advance and the velocity of the knife increases, the firing force F increases and reaches a first peak value  5754  when a first row of staples is driven from the staple cartridge. After the first row of staples is driven as described hereinabove, the firing force F decreases until a second row of staples is driven, which causes the firing force F to reach a second peak value  5756 . 
     At a later point in the firing motion, the slope of the firing force signal reaches or exceeds a predetermined threshold (this condition is shown as the slope A1 of the firing force signal in  FIG.  118   ) and the amplitude of the firing force F reaches or exceeds a predetermined amplitude threshold (e.g., the amplitude Fcrit shown in  FIG.  118   ). In response, the control algorithm acts to slow down, stop or pause the further advancement of the knife and the firing force F begins to decrease. 
     For the example graph  5752 , the slowing down, stopping or pausing of the knife continues until the firing force F reaches a value which is 10% less than the predetermined amplitude threshold (e.g., Fcrit), at which point the further advancement of the knife is commenced. Of course, in accordance with one or more aspects, the further advancement of the knife can be commenced when the firing force reaches a value which is less than or more than the 10% example shown in  FIG.  118   . The above-described automatic stopping or pausing and automatic restarting may be repeated any number of times. 
     For the example graph  5752 , once the further advancement of the knife is commenced, as the knife advances towards its fully advanced position the slope of the firing force signal once again reaches or exceeds the predetermined slope threshold (this condition is shown as the slope A2 of the firing force signal in  FIG.  118   ). However, because the predetermined slope threshold was reached or exceeded while the knife was in zone 4 of the firing motion, the control algorithm ignores this “slope” trigger and continues advancing the knife to its fully advanced position, resulting in the firing force decreasing to zero as indicated at the far right side of  FIG.  118   . 
     In addition to ignoring triggers, thresholds and/or events based on where the triggers, thresholds and/or events occur within the firing motion, the control algorithms may also vary or modify the triggers, thresholds and/or events based on where the triggers, thresholds and/or events occur within the firing motion. For example, in accordance with one or more aspects, the control algorithms may set the value for a predetermined slope threshold at a first value for zone 1 of the firing motion, at a second value for zone 2 of the firing motion, at a third value for zone 3 of the firing motion, etc. 
       FIG.  119    illustrates an example graph  5770  showing a curve representative of a closing force FC over time t for various aspects of the surgical instrument and a curve representative of a firing force FF over time t for the surgical instrument  5700  of  FIG.  115   .  FIG.  119    illustrates an example graph  5770  showing a curve  5772  representative of a closing force FC over time t for various aspects of the surgical instrument  5700  and a curve  5774  representative of a firing force FF over time t for various aspects of the surgical instrument  5700 . The closing force FC is shown along the “left” vertical axis, the firing force FF is shown along the “right” vertical axis and the time t is shown along the horizontal axis. When viewed together the curves  5772 ,  5774  reflect the timing of the closing motion and the firing motion relative to one another, where the closing motion is initiated prior to the initiation of the firing motion. Although the example graph  5770  shows a threshold force Fcrit as being the same amplitude for both the closing force FC and the firing force FF, it will be appreciated that the amplitude of the threshold force Fcrit for the closing force FC may be different from the amplitude of the threshold force Fcrit for the firing force FF. Stated differently, the scale of the “left” vertical axis can be different from the scale of the “right” vertical axis. 
     The curve  5772  is a graphical representation of the closing force signal at various times during a closing motion. Thus, as set forth hereinabove, the curve  5772  may be generated mathematically by the controller based on the closing force signal(s) received by the controller. The closing force FC represented on the “left” vertical axis may be a force experienced by tissue clamped between the jaws of the surgical instrument  5700 , a force experienced by the jaws of the surgical instrument  5700  (e.g., by the anvil and/or the elongated channel), a force experienced by the closure tube of the surgical instrument  5700 , and/or any combinations thereof. The closing force FC can be measured in any suitable manner, either directly or indirectly. For example, according to various aspects, the closing force FC can be measured directly by a sensor (e.g., a strain gauge) positioned on the anvil, on the elongated channel, on the closure tube, or indirectly by an impedance of the tissue, a current draw of the motor, and/or any combinations thereof. 
     The curve  5774  is a graphical representation of the firing force signal at various times during a firing motion and may be similar or identical to the curve  5752  of  FIG.  109   . Thus, as set forth hereinabove, the curve  5774  may be generated mathematically by the controller based on the firing force signal(s) received by the controller. The firing force FF represented on the “right” vertical axis may be a force experienced by the drive system of the surgical instrument  5700  (e.g., by the sled, the knife, and/or the firing bar), and/or any combination thereof. The firing force FF can be measured in any suitable manner, either directly or indirectly. For example, according to various aspects, the firing force FF can be measured directly by a sensor (e.g., a strain gauge) positioned on the sled, on the knife, or indirectly by a current draw of the motor, and/or any combination thereof. Although not shown for purposes of simplicity, the respective zones of the firing cycle (e.g., zones 1-5 as described hereinabove) could also be shown along the horizontal axis. 
     For the example graph  5770  in  FIG.  110   , at some time after the closing motion has commenced, the knife is still in the fully-retracted position and the firing force FF is approximately zero. As the knife and sled advance and the velocity of the knife increases, the firing force FF increases and reaches a first peak value  5776  when a first row of staples is driven from the staple cartridge. After the first row of staples is driven as described hereinabove, the firing force FF decreases until a second row of staples is driven, which causes the firing force FF to reach a second peak value  5778 . 
     At a later point in the firing motion, the slope of the firing force signal reaches or exceeds a predetermined threshold (this condition is shown as the slope A of the firing force signal in  FIG.  117   ) and the amplitude of the firing force FF reaches or exceeds a predetermined amplitude threshold (e.g., the amplitude Fcrit shown in  FIG.  117   ). In response, the control algorithm acts to slow down, stop or pause the further advancement of the knife and the firing force FF begins to decrease. 
     For the example graph  5770 , the slowing down, stopping or pausing of the knife continues until the firing force FF reaches a value which is 10% less than the predetermined amplitude threshold (e.g., Fcrit), at which point the further advancement of the knife is commenced. Of course, according to various aspects, the further advancement of the knife can be commenced when the firing force FF reaches a value which is less than or more than the 10% example shown in  FIG.  117   . The above-described automatic stopping or pausing and automatic restarting may be repeated any number of times. 
     For the example graph  5770 , once the further advancement of the knife is commenced, as the knife advances towards its fully advanced position the slope of the firing force signal once again reaches or exceeds the predetermined slope threshold (this condition is shown as the slope B of the firing force signal in  FIG.  117   ). However, because the predetermined slope threshold was reached or exceeded while the knife was in zone 4 (not shown) of the firing motion, the control algorithm ignores this “slope” trigger and continues advancing the knife to its fully advanced position, resulting in the firing force decreasing to zero as indicated at the far right side of  FIG.  117   . 
       FIG.  120    illustrates an example graph  5760  showing a first curve  5762  representative of a firing force F over time t for various aspects of the surgical instrument  5700 , a knife position X over time t for various aspects of the surgical instrument  5700  and a second curve  5764  representative of knife velocity V over time t for various aspects of the surgical instrument  5700 . The firing force F is shown along the top vertical axis, the knife velocity V is shown along the bottom vertical axis, the knife position X is shown along the top horizontal axis and the time t are shown along both the top and bottom the horizontal axes. As shown along the top horizontal axis, the knife position X travels over five Zones 1-5 along the knife channel in the cartridge  304  located in the lower jaw  302  of the end effector  300  of the surgical instrument  5700 . The knife velocity V and the firing force F shown in  FIG.  120    may be based on the assumption that the thickness and composition of the tissue along the cut line is uniform. 
     Accordingly, the curve  5762  is a representation of the firing force signal at various times during a firing motion and the curve  5764  is a representation of the knife velocity signal at various times during a firing motion. The curves  5762 ,  5764  may be generated mathematically by the controller based on the firing force signal(s) and the knife velocity signal(s) received by the controller. The firing force F represented on the top vertical axis may be a force experienced by the drive system of the surgical instrument  5500  (e.g., by the sled, the knife and/or the firing bar), and/or any combination thereof. The firing force F can be measured in any suitable manner, either directly or indirectly. For example, in accordance with one or more aspects, the firing force F can be measured directly by a sensor (e.g., a strain gauge) positioned on the sled, on the knife, or indirectly by a current draw of the motor, and/or any combination thereof. 
     The knife velocity V represented on the bottom vertical axis may be a velocity of the knife, a velocity of the sled, a velocity of another component of the drive system (e.g., the firing bar), and/or any combination thereof. The knife velocity V can be measured in any suitable manner, either directly or indirectly. For example, in accordance with one or more aspects, the knife velocity V can be measured directly by a combination of a magnet positioned on the firing bar and a Hall-effect sensor or indirectly by a current draw of the motor, an encoder coupled to the shaft of the motor, and/or any combination thereof. 
     For the example graph  5764 , the knife velocity V is shown as increasing from zero to a substantially maximum velocity while the knife advances from its fully retracted position through zone 1 and into zone 2 of the firing motion. Even if the change of the firing force F over time (e.g., the slope ΔF/Δt shown occurring in zone 1 and/or zone 2) reaches or exceeds a predetermined threshold, the control algorithm may ignore this trigger, threshold and/or event and allow the knife to continue advancing as shown by the knife velocity V in  FIG.  120   . Once the substantially maximum velocity is reached in zone 2, the knife continues to advance in zone 2 and zone 3 until another trigger, threshold and/or event prompts the control algorithm to automatically stop the advancement of the knife. For the example graph  5762 , this occurs in zone 3 when the firing force F exceeds the predetermined threshold Fcrit. According to other aspects, the trigger, threshold and/or event could be a change of firing force F over time t reaching or exceeding a certain value, a combination of the change of firing force F over time t reaching or exceeding a certain value and the firing force F reaching or exceeding a certain value, a change of a peak-to-peak firing force over time t reaching or exceeding a certain value, a combination of a change of a peak-to-peak firing force over time t reaching or exceeding a certain value and the firing force F reaching or exceeding a certain value, etc. 
     Once the firing force F reaches or exceeds the predetermined threshold Fcrit and the knife is in a position associated with zone 3 of the firing motion, the control algorithm automatically stops or pauses the further advancement of the knife and the knife velocity V falls from a substantially constant velocity to zero at time t 1 . In other words, instead of ignoring the trigger, the control algorithm acts on the trigger and changes the firing motion. After a predefined period of time (e.g., the time period t 2 −t 1 ) as shown in  FIG.  120    or a predefined drop in the amplitude of the firing force F, the control algorithm automatically restarts the advancement of the knife and the knife velocity V increases from zero at time t 2  to a substantially maximum velocity, then continues in zone 3 and zone 4 at a substantially constant velocity. At some point in zone 4, the knife velocity drops from a substantially constant velocity to zero and the firing force also drops to zero. 
     Although  FIG.  120    depicts the control algorithm as not acting on a firing force trigger, threshold and/or event which occurs in zone 2 of the firing motion and acting on a firing force trigger, threshold and/or event which occurs in zone 3 of the firing motion, it will be appreciated that the control algorithm can be configured to act or not act on firing force triggers, thresholds and/or events which occur in other zones of the firing motion. For example, as described hereinabove with respect to  FIG.  118   , the control algorithm can be configured to not act (ignore) a firing force trigger, threshold and/or event which occurs in zone 4 of the firing motion. 
     Furthermore, although the functionality of the control algorithms described in connection with  FIGS.  115 - 120    were described in the context of ignoring or varying triggers, thresholds and/or events during the firing motion, it will be appreciated that the control algorithms of the surgical instrument  5700  may also be configured to ignore or vary triggers, thresholds and/or events during the closing cycle (i.e., the closing of the jaws). 
       FIG.  121    illustrates a perspective view of a surgical instrument  5800  according to various aspects described herein. The surgical instrument  5800  is similar to the surgical instrument  5500  and includes an elongated channel configured to support a staple cartridge, an anvil pivotably connected to the elongated channel, a closure member mechanically coupled to the anvil, a knife mechanically coupled to the staple cartridge, an electric motor mechanically coupled to the closure member and/or the knife, a motor controller electrically coupled to the motor, and a control circuit electrically coupled to the motor controller. The surgical instrument  5800  is also similar to the surgical instrument  5500  in that the surgical instrument  5800  also includes sensors which are collectively configured to sense or measure a closing force, a firing force, a current drawn by the electric motor, an impedance of tissue positioned between the elongated channel and the anvil, a position of the anvil relative to the elongated channel, a position of the knife, or any combination thereof. The surgical instrument  5500  is also similar to the surgical instrument  5800  in that the surgical instrument  5800  also includes algorithms such as closing algorithms, firing algorithms, motor control algorithms, or any combination thereof, which operate to dynamically adjust the operation of the surgical instrument  5800 . However, the surgical instrument  5800  is different from the surgical instrument  5500  in that the surgical instrument  5800  further includes one or more additional algorithms (in addition to those described hereinabove) which provide additional control functionality for the surgical instrument  5800 , as described herein below. 
     In certain aspects, for different circumstances, the control algorithms are configured to automatically invoke different adjustments to the closing motion and/or the firing motion. For example, in certain aspects, a control algorithm is configured to adjust the firing motion based on how fast the load is increasing or decreasing as it approaches a predefined staged threshold. For such aspects, a first adjustment to the firing motion may be invoked when the load is increasing at a first rate as it approaches a predefined threshold, and a second adjustment to the firing motion may be invoked when the load is increasing at a second rate as it approaches a predefined threshold. In other aspects, the control algorithms are configured to adjust the closure algorithm and/or the firing algorithm based on how fast aspects of the closing force, the closure tube velocity, the firing force, the knife velocity, the motor current and combinations thereof are increasing or decreasing as they approaches respective predefined staged thresholds. 
       FIG.  122    illustrates a method  5810  of controlling a firing motion of the surgical instrument  5800  according to various aspects. The process starts when a firing motion is initiated  5812 . The firing motion may be initiated, for example, by pulling a firing trigger toward a handle A sensor resident with the surgical instrument  5800  senses/measures  5814  a firing force. The firing force may be, for example, a force experienced by the drive system of the surgical instrument (e.g., by the sled, the knife and/or the firing bar), and/or any combination thereof. The firing force F can be measured in any suitable manner, either directly or indirectly. For example, according to various aspects, the firing force F can be measured directly by a sensor (e.g. a strain gauge) positioned on the sled, on the knife, or indirectly by a current draw of the motor. 
     In response to the firing force, the sensor outputs  5816  a firing force signal, which is indicative of the firing force sensed/measured  5814  by the sensor. Depending on the configuration of the sensor, the firing force signal can be an analog signal or a digital signal. Upon determining  5818  whether the firing force signal is either an analog signal or a digital signal, the process proceeds along the corresponding branch. When the determination  5818  is that the firing force signal is an analog signal, the process proceeds along the analog branch, where the analog signal is received by an A/D converter, converted  5820  to a digital signal representative of the analog signal by the A/D converter and the digital signal is output by the A/D converter. When the determination  5818  is that the firing force signal is a digital signal, the process proceeds along the digital branch because there is no need for an A/D conversion  5820  when the firing force signal is a digital signal. 
     The firing force signal which is a digital signal representative of the firing force sensed/measured  5814  by the sensor is received by a controller. The controller utilizes the digital signal and determines  5822  a projected peak firing force. According to various aspects, the projected peak firing force is determined by constructing a straight line which passes through the two most recent peak values of the firing force signal, projecting when the next peak firing force will occur and determining the value of the firing force on the straight line at that time. The straight line is representative of a change of peak firing force values over time and may thus be considered a slope of the peak firing force values. The controller may project when the next peak firing force will occur in any suitable manner. For example, according to various aspects, the controller may utilize the time lapse between the last two peak firing forces, the average of the time lapses between each of the peak firing forces which have occurred in a given firing motion, the pattern or trend of the time lapses between each of the peak firing forces which have occurred in a given firing motion and combinations thereof. 
     After the controller determines  5822  that the projected peak firing force, the controller then determines  5824  whether or not the firing motion should be changed. The determination  5824  may be based, for example, on how fast or slow the projected peak firing force is approaching a predetermined threshold, on the amplitude of the firing force and how fast or slow the projected peak firing force is approaching a predetermined threshold, and combinations thereof. In other words, the determination  5824  may be based on the amplitude of the firing force and the value of the slope of the peak firing force values as the slope is approaching a predetermined threshold. The predetermined threshold may be any suitable threshold such as, for example, a predetermined firing force threshold. When the controller determines  5824  that the firing motion should not be changed, the firing motion originally initiated  5812  is continued  5826  along with interim processes  5814 - 5824 . When the controller determines  5824  that the motion should be changed, the firing motion may be changed in a multitude of different ways, with the particular way determined based on how fast or slow the projected peak firing force is approaching a predetermined threshold. 
     According to various aspects, when the projected peak firing force is approaching a predetermined threshold at a first rate, the controller may stop or pause  5828  the firing motion by communicating a stop signal or a pause signal to the motor controller to stop or pause the rotation of the motor(s) which drive the sled, knife, firing bar or any combination thereof of the surgical instrument  5800 . After the firing motion is stopped or paused, the firing motion may be subsequently terminated  5830  or the controller may restart  5832  the firing motion by communicating a restart signal to the motor controller to restart the rotation of the motor(s) which drive the sled, knife, firing bar or any combination thereof of the surgical instrument  5800 . The firing motion may be restarted  5832  based on, for example, a period of time, a predetermined drop in the firing force and combinations thereof. After the firing motion is restarted  5832 , interim processes  5814 - 5824  of the firing motion originally initiated  5812  are continued. 
     According to various aspects, when the projected peak firing force is approaching a predetermined threshold at a second rate, the controller may change the firing motion to decrease the knife velocity  5834  by communicating a slow down signal to the motor controller to slow down the rotation of the motor(s) which drive the sled, knife, firing bar or any combination thereof of the surgical instrument  5800 . Similarly, according to various aspects, when the projected peak firing force is approaching a predetermined threshold at a third rate, the controller may change the firing motion to increase the knife velocity  5836  by communicating a speed up signal to the motor controller to speed up the rotation of the motor(s) which drive the sled, knife, firing bar or any combination thereof of the surgical instrument  5800 . 
     According to various aspects, when the projected peak firing force is approaching a predetermined threshold at a fourth rate, the controller may change the firing motion to oscillate the knife  5838  by communicating an oscillation signal to the motor controller to alternate the rotation of the motor(s) which drive the sled, knife, firing bar or any combination thereof of the surgical instrument  5800  in a clockwise direction and a counterclockwise direction, thereby producing a back and forth motion of the sled, knife, firing bar or any combination thereof. 
       FIG.  123    illustrates an example graph  5850  showing a first curve  5852  representative of a firing force F over time t for various aspects of the surgical instrument  5800 , a knife position X over time t for various aspects of the surgical instrument  5800  and a second curve  5854  representative of knife velocity V over time t for various aspects of the surgical instrument  5800 . The firing force F is shown along the top vertical axis, the knife velocity V is shown along the bottom vertical axis, the knife position X is shown along both the top and bottom horizontal axes and the time t is shown along both the top and bottom the horizontal axes. As shown along the top an bottom horizontal axes, the knife position X travels over five zones (zones 1-5) along the knife channel in the cartridge  304  located in the lower jaw  302  of the end effector  300  of the surgical instrument  5800 . The knife velocity V and the firing force F shown in  FIG.  123    may be based on the assumption that the thickness and composition of the tissue  5856  along the cut line is non-uniform as shown on the far right side of  FIG.  123   . 
     Accordingly, the curve  5852  is a representation of the firing force signal at various times during a firing motion and the curve  5854  is a representation of the knife velocity signal at various times during a firing motion. The curves  5852 ,  5854  may be generated mathematically by the controller based on the firing force signal(s) and the knife velocity signal(s) received by the controller. The firing force F represented on the top vertical axis may be a force experienced by the drive system of the surgical instrument  5800  (e.g., by the sled, the knife and/or the firing bar), and/or any combination thereof. The firing force F can be measured in any suitable manner, either directly or indirectly. For example, according to various aspects, the firing force F can be measured directly by a sensor (e.g., a strain gauge) positioned on the sled, on the knife, or indirectly by a current draw of the motor, and/or any combination thereof. 
     The knife velocity V represented on the bottom vertical axis may be a velocity of the knife, a velocity of the sled, a velocity of another component of the drive system (e.g., the firing bar), and/or any combination thereof. The knife velocity V can be measured in any suitable manner, either directly or indirectly. For example, according to various aspects, the knife velocity V can be measured directly by a combination of a magnet positioned on the firing bar and a Hall-effect sensor or indirectly by a current draw of the motor, an encoder coupled to the shaft of the motor, and/or any combination thereof. 
     For the example graph  5840 , the curve  5854  shows the knife velocity V increasing from zero at time t=0 to a substantially maximum velocity V 1  while the knife advances from its fully retracted position through zone 1 and into zone 2 of the firing motion. Once the substantially maximum velocity V 1  is reached in zone 2, the knife continues to advance in zone 2 and zone 3 until a trigger, threshold and/or event prompts the control algorithm to automatically change the firing motion, in this case decreasing the knife velocity V. Such a trigger, threshold or event is shown in the curve  5852 , where the projected peak firing force on the slope (ΔF 1 /Δt 1 ) reaches or exceeds a predetermined threshold (e.g., the firing force value Fcrit) at the time t 1 . As shown in  FIG.  123   , the time t 1  may correspond to the knife cutting through a portion of tissue  5856  which is less than a full thickness of the tissue  5856 . 
     Once the projected peak firing force on the slope (ΔF 1 /Δt 1 ) reaches or exceeds the predetermined threshold Fcrit and the knife is in a position associated with zone 3 of the firing motion at time t 1 , the control algorithm changes the firing motion to decrease the knife velocity from the substantially maximum velocity V 1  to the reduced velocity V 2 . Although the velocity V 2  is shown as being approximately ⅔ of the velocity V 1 , it will be appreciated that the decrease in the knife velocity V can be more or less than ⅓ of the maximum velocity V 1 . According to various aspects, the amount of the decrease is based on the value of the slope (ΔF 1 /Δt 1 ), essentially how quickly the peak firing forces are approaching the predetermined threshold. The knife then advances at the reduced velocity V 2  in zone 3 until another trigger, threshold and/or event prompts the control algorithm to automatically change the firing motion, in this case further decreasing the knife velocity V. Such a trigger, threshold or event is shown in the curve  5852 , where the projected peak firing force on the slope (ΔF 2 /Δt 2 ) reaches or exceeds a predetermined threshold (e.g., the firing force value Fcrit) at the time t 2 . As shown in  FIG.  123   , the time t 2  may correspond to the knife cutting through a portion of tissue  5856  which is the full thickness of the tissue  5856 . 
     Once the projected peak firing force on the slope (ΔF 2 /Δt 2 ) reaches or exceeds the predetermined threshold Fcrit and the knife is in a position associated with zone 3 of the firing motion at time t 2 , the control algorithm again changes the firing motion to further decrease the knife velocity from the reduced V 2  to the further reduced velocity V 3 . Although the velocity V 3  is shown as being approximately ⅓ of the velocity V 1  and ½ of the velocity V 2 , it will be appreciated that the further decrease in the knife velocity V can be more or less than ⅓ of the maximum velocity V 1  or more or less than ½ of the previous velocity V 2 . According to various aspects, the amount of the decrease is based on the value of the slope (ΔF 2 /Δt 2 ), essentially how quickly the peak firing forces are approaching the predetermined threshold. 
     After the time t 2 , the knife continues advancing through zones 3 and 4 of the firing motion at the velocity V 2 , then begins dropping in zone 4 and reaches zero in zone 5 of the firing motion. As shown in the curve  5852 , the firing force F also drops to zero in zone 5. Due to the differences in the knife velocity V brought about by the controller, it will be appreciated that the time period Δt 1 , the time between successive valley firing force values when the knife is in zone 2 of the firing motion and advancing at the velocity V 1 , is less than the time period Δt 2 , the time between successive valley firing force values when the knife is in zone 3 of the firing motion and advancing at the velocity V 2 , which is less than the time period Δt 3 , the time between successive valley firing force values when the knife is in zone 3 of the firing motion and advancing at the velocity V 3 . 
     Although  FIG.  123    depicts the control algorithm as acting to reduce the knife velocity V based on triggers, thresholds and/or events which occur in zones 2 and/or 3 of the firing motion, it will be appreciated that the control algorithm can be configured to act to increase the knife velocity, oscillate the knife and combinations thereof in zones 2 and 3 of the firing motion and/or in other zones of the firing motion. For example, when the peak firing forces are rapidly approaching a predetermined threshold (i.e., the slope is steep), the firing algorithm may interpret this as an obstruction to the knife and change the firing motion to stop the advancement of the knife then create an oscillating motion. The stop, backup, re-advance, stop, backup, re-advance pattern assists the knife in moving through the obstruction. 
     Furthermore, although the functionality of the control algorithms described in connection with  FIG.  123    were described in the context of adjusting the knife velocity V, it will be appreciated that the control algorithms of the surgical instrument  5800  may also be configured to adjust the closure tube velocity during the closing motion (i.e., the closing of the jaws). Similarly, the control algorithms may operate to change the closing motion such that the anvil vibrates/oscillates toward a fully closed position to improve compression of the tissue  5856 . 
       FIG.  124    illustrates the rate of closure of the jaws (jaws closure speed) for the surgical instrument of  FIG.  121    in accordance with one or more aspects of the present disclosure. In other words, the rate of closure of the anvil  306  closing onto the staple cartridge  304  with tissue located therebetween. The top graph  5860  represents the jaws closing at a constant speed where the jaw closing force (F) is represented along the vertical axis as the knife advances over a longitudinal distance (X) in the cartridge  304 , as represented along the horizontal axis, until the stop trigger is actuated by the control program at X 1 . The stop trigger stops the jaws from closing for a period of time prior to initiating the firing stroke. As previously described herein, this enables the jaws to squeeze excess moisture from the tissue prior to initiating the firing stroke after a brief delay period of 5 to 20 seconds and preferably about 15 seconds. At X 1 , the jaws closing force reaches a peak amplitude and the gap between the jaws is set to a predetermined distance. Still with reference to the top graph  5860 , the first curve  5862  represents the force over distance as the jaws close at a first constant speed until the stop trigger stops the jaws from closing at X 1 . At this point, the force F reaches a peak force of F 1  and the gap between the jaws is set to a first distance. The second curve  5864  represents the force over distance as the jaws close at a second speed, which is less than the first speed, until the stop trigger stops the jaws from closing at X 1 . The first jaw closing speed is adjusted to the second closing speed by the control circuit when the control circuit predicts that the closing force will be too high. At X 1 , the force F reaches a peak force of F 2 , which is less than F 1 , and the gap between the jaws is set to a second distance which is less than the first distance. 
     With reference still to  FIG.  124   , the bottom graph  5866  represents the jaws closing force (F) along the vertical axis and time (t) along the horizontal axis. The first curve  5867  represents the jaws closing force over time as the jaws close at a constant speed. As shown by the first curve  5867 , when the jaws closing speed is constant, the jaws can experience a force that reaches a maximum F 1  that is too high and reaches this peak force F 1  before the stop trigger is activated. Accordingly, when the control circuit predicts that the jaws closing force will be high, the control circuit slows down the jaws closure speed after a period of t 1 . At the lower jaw closing speed the second curve  5869  can lead to a lower force (and a lower gap) and ultimately a lower peak force F 2  (and gap) after a period t 2  prior to initiating a firing stroke. As shown, the stop trigger actually changes speed the keep the jaws closing force F below the slope threshold  5868 . 
     In various aspects, the control algorithms operate to effectively take control of the surgical instrument during the closing and/or firing motions. In certain aspects, a control algorithm automatically operates the surgical instrument in a cutting mode which optimizes staple form. For example, an exemplary control algorithm advances the knife in three incremental stages to optimize staple form. In the first stage, the knife is advanced distally a small increment (e.g., 3 mm) and is then stopped. Pressure applied to the tissue near the knife operates to force fluid out of the tissue. The knife remains stopped until a predetermined time passes, a sensor (pressure, distance, etc.) in the distal shaft indicates an asymptote, and combinations thereof. In the second stage, the knife is retracted proximally a smaller distance (e.g., 1 mm) from the first stage stopping point and is then stopped. The distance between the first stage stopping point and the second stage stopping point allows for the knife acceleration which occurs in the third stage. In the third stage, the knife is driven distally at a rapid speed until sufficient knife advancement is made to drive/form one staple (or one row of staples). The high speed move forms the staple quickly, reducing the chances of staple buckling and improving form quality. High speed forming is a technique used in nail guns, particularly in finishing nails that are extremely prone to buckling. The three stages are repeated for each row of staples for the length of the cut, effectively ratcheting through the tissue. 
     According to certain aspects, the surgical instrument includes a button which can be utilized by an operator to selectively enable or disable the above-described cutting mode. The button may be positioned on the shaft. Although the cutting mode was described as a cutting mode which optimizes staple form, it will be appreciated that according to other aspects the control algorithm may operate the surgical instrument in a cutting mode which is different than that described hereinabove. 
     While various details have been set forth in the foregoing description, it will be appreciated that the various aspects of the motorized surgical instruments may be practiced without these specific details. For example, for conciseness and clarity selected aspects have been shown in block diagram form rather than in detail. Some portions of the detailed descriptions provided herein may be presented in terms of instructions that operate on data that is stored in a computer memory. Such descriptions and representations are used by those skilled in the art to describe and convey the substance of their work to others skilled in the art. In general, an algorithm refers to a self-consistent sequence of steps leading to a desired result, where a “step” refers to a manipulation of physical quantities which may, though need not necessarily, take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It is common usage to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. These and similar terms may be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. 
     Although various aspects have been described herein, many modifications, variations, substitutions, changes, and equivalents to those aspects may be implemented and will occur to those skilled in the art. Also, where materials are disclosed for certain components, other materials may be used. It is therefore to be understood that the foregoing description and the appended claims are intended to cover all such modifications and variations as falling within the scope of the disclosed aspects. The following claims are intended to cover all such modification and variations. 
     In a general sense, those skilled in the art will recognize that the various aspects described herein which can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or any combination thereof can be viewed as being composed of various types of “electrical circuitry.” Consequently, as used herein “electrical circuitry” includes, but is not limited to, electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer configured by a computer program which at least partially carries out processes and/or devices described herein, or a processor configured by a computer program which at least partially carries out processes and/or devices described herein), electrical circuitry forming a memory device (e.g., forms of random access memory), and/or electrical circuitry forming a communications device (e.g., a modem, communications switch, or optical-electrical equipment). Those having skill in the art will recognize that the subject matter described herein may be implemented in an analog or digital fashion or some combination thereof. 
     The foregoing detailed description has set forth various aspects of the devices and/or processes via the use of block diagrams, flowcharts, and/or examples. Insofar as such block diagrams, flowcharts, and/or examples contain one or more functions and/or operations, it will be understood by those within the art that each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In one aspect, several portions of the subject matter described herein may be implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), or other integrated formats. Those skilled in the art will recognize, however, that some aspects of the aspects disclosed herein, in whole or in part, can be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure. 
     In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein are capable of being distributed as a program product in a variety of forms, and that an illustrative aspect of the subject matter described herein applies regardless of the particular type of signal bearing medium used to actually carry out the distribution. Examples of a signal bearing medium include, but are not limited to, the following: a recordable type medium such as a floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), a digital tape, a computer memory, etc.; and a transmission type medium such as a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link (e.g., transmitter, receiver, transmission logic, reception logic, etc.). 
     In summary, numerous benefits have been described which result from employing the concepts described herein. The foregoing description of the one or more aspects has been presented for purposes of illustration and description. It is not intended to be exhaustive or limiting to the precise form disclosed. Modifications or variations are possible in light of the above teachings. The one or more aspects were chosen and described in order to illustrate principles and practical application to thereby enable one of ordinary skill in the art to utilize the various aspects and with various modifications as are suited to the particular use contemplated. It is intended that the claims submitted herewith define the overall scope.