Patent Publication Number: US-2022226013-A1

Title: Surgical instrument soft stop

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. 15/982,352, entitled SURGICAL INSTRUMENT SOFT STOP, filed May 17, 2018, now U.S. Patent Application Publication No. 2018/0333155, which is a continuation application claiming priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 15/074,296, entitled SURGICAL INSTRUMENT SOFT STOP, filed Mar. 18, 2016, which issued on Mar. 3, 2020 as U.S. Pat. No. 10,575,868, which is a continuation application claiming priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 13/782,536, entitled SURGICAL INSTRUMENT SOFT STOP, filed Mar. 1, 2013, which issued on Apr. 12, 2016 as U.S. Pat. No. 9,307,986, the entire disclosures of which are hereby incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to surgical instruments and, in various arrangements, to surgical cutting and stapling instruments and staple cartridges therefor that are designed to cut and staple tissue. 
     BACKGROUND 
     Surgical staplers are often used to deploy staples into soft tissue to reduce or eliminate bleeding from the soft tissue, especially as the tissue is being transected, for example. Surgical staplers, such as an endocutter, for example, can comprise an end effector which can be moved, or articulated, with respect to an elongate shaft assembly. End effectors are often configured to secure soft tissue between first and second jaw members where the first jaw member often includes a staple cartridge which is configured to removably store staples therein and the second jaw member often includes an anvil. Such surgical staplers can include a closing system for pivoting the anvil relative to the staple cartridge. 
     Surgical staplers, as outlined above, can be configured to pivot the anvil of the end effector relative to the staple cartridge in order to capture soft tissue therebetween. In various circumstances, the anvil can be configured to apply a clamping force to the soft tissue in order to hold the soft tissue tightly between the anvil and the staple cartridge. If a surgeon is unsatisfied with the position of the end effector, however, the surgeon must typically activate a release mechanism on the surgical stapler to pivot the anvil into an open position and then reposition the end effector. Thereafter, staples are typically deployed from the staple cartridge by a driver which traverses a channel in the staple cartridge and causes the staples to be deformed against the anvil and secure layers of the soft tissue together. Often, as known in the art, the staples are deployed in several staple lines, or rows, in order to more reliably secure the layers of tissue together. The end effector may also include a cutting member, such as a knife, for example, which is advanced between two rows of the staples to resect the soft tissue after the layers of the soft tissue have been stapled together. 
     Such surgical staplers and effectors may be sized and configured to be inserted into a body cavity through a trocar or other access opening. The end effector is typically coupled to an elongate shaft that is sized to pass through the trocar or opening. The elongate shaft assembly is often operably coupled to a handle that supports control systems and/or triggers for controlling the operation of the end effector. To facilitate proper location and orientation of the end effector within the body, many surgical instruments are configured to facilitate articulation of the end effector relative to a portion of the elongate shaft. 
     The foregoing discussion is intended only to illustrate various aspects of the related art in the field of the invention at the time, and should not be taken as a disavowal of claim scope. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a surgical stapling instrument of one form of the present invention; 
         FIG. 2  is another perspective view of the surgical instrument of  FIG. 1  with a portion of the handle housing removed; 
         FIG. 3  is an exploded assembly view of one effector arrangement of the present invention 
         FIG. 4  is a partial cross-sectional view of a portion of the end effector and the elongate shaft assembly of the surgical instrument of  FIGS. 1 and 2  with the anvil assembly in an open position; 
         FIG. 5  is another partial cross-sectional view of the end effector and elongate shaft assembly of  FIG. 4  with the anvil assembly in a closed position prior to firing; 
         FIG. 6  is another partial cross-sectional view of the end effector and elongate shaft assembly of  FIGS. 4 and 5  after the tissue cutting member has been advanced to a distal-most position within the end effector; 
         FIG. 7  is a perspective view of a coupler assembly arrangement of the present invention; 
         FIG. 8  is an exploded assembly view of the coupler assembly of  FIG. 7 ; 
         FIG. 9  is a perspective view of the proximal end of the end effector and the distal end of the elongate shaft assembly and coupler assembly attached thereto; 
         FIG. 10  is an elevational view of the proximal end of the end effector of  FIG. 9 ; 
         FIG. 11  is an elevational view of the distal end of the coupler assembly of  FIG. 9 ; 
         FIG. 12  is a perspective assembly view of a portion of the end effector and elongate shaft assembly prior to coupling the end effector thereto; 
         FIG. 13  is another perspective view of a portion of an end effector and elongate shaft assembly arrangement after the end effector has been initially engaged with a coupler assembly portion of the elongate shaft assembly; 
         FIG. 14  is another perspective view of the components depicted in  FIG. 13  after the end effector has been coupled to the coupler assembly portion of the elongate shaft assembly; 
         FIG. 15  is a perspective view of an articulation control arrangement of the present invention; 
         FIG. 16  is a perspective view of a portion of an articulation shaft segment arrangement; 
         FIG. 17  is an exploded perspective view of an articulation joint arrangement of the present invention; 
         FIG. 18  is a perspective view of the articulation joint arrangement of  FIG. 17 ; 
         FIG. 19  is a top view of the articulation joint arrangement of  FIGS. 17 and 18 ; 
         FIG. 20  is a cross-sectional view of the components illustrated in  FIG. 19 ; 
         FIG. 21  is another cross-sectional view of the articulation joint of  FIGS. 19 and 20 ; 
         FIG. 22  is another cross-sectional view of the articulation joint of  FIG. 21  in an articulated configuration; 
         FIG. 23  is a perspective view of a firing system arrangement of the present invention; 
         FIG. 24  is a perspective view of an end effector rotation system arrangement of the present invention; 
         FIG. 25  is a perspective view of a portion of an articulation joint and coupler assembly of the present invention; 
         FIG. 26  is a perspective view of a shaft rotation system arrangement of the present invention; 
         FIG. 27  is an exploded perspective view of the surgical instrument of  FIGS. 1 and 2 ; 
         FIG. 28  is an exploded perspective view of a detachable drive mount arrangement of the present invention; 
         FIG. 28A  is an end elevational view of a portion of the detachable drive mount arrangement of  FIG. 28  attached to a motor mounting assembly arrangement; 
         FIG. 28B  is a perspective view of a portion of the detachable drive mount arrangement and motor mounting assembly arrangement of  FIG. 28A ; 
         FIG. 29  is a cross-sectional view of a portion of a handle assembly arrangement; 
         FIG. 30  is an exploded assembly view of a detachable drive mount and motor mounting assembly within the handle housing portions; 
         FIG. 31  is an exploded assembly view of a motor mounting assembly arrangement; 
         FIG. 32  is another an exploded cross-sectional assembly view of the detachable drive mount and motor mounting assembly within the handle housing portions; 
         FIG. 33  is a side elevational view of a portion of the handle assembly with various components omitted for clarity; 
         FIG. 34  is a bottom perspective view of a switch arrangement of the present invention; 
         FIG. 35  is an exploded assembly view of the switch arrangement of  FIG. 34 ; 
         FIG. 36  is a cross-sectional view of portion of the switch arrangement of  FIGS. 34 and 35  mounted with the handle assembly wherein the joy stick control portion is in an unactuated position; 
         FIG. 37  is another cross-sectional view of the switch arrangement of  FIG. 36  with the joy stick control portion in an actuated position; 
         FIG. 38  is a side cross-sectional view of the switch arrangement of  FIG. 36 ; 
         FIG. 39  is a side cross-sectional view of the switch arrangement of  FIG. 37 ; 
         FIG. 40  is a side elevational view of the switch arrangement of FIGS. 34-39; 
         FIG. 41  is a front elevational view of the switch arrangement of  FIGS. 34-40 ; 
         FIG. 42  is another exploded assembly view of the switch arrangement of  FIGS. 34-41 ; 
         FIG. 43  is a rear elevational view of a thumbwheel paddle control assembly arrangement in an actuated position; 
         FIG. 44  is another rear elevational view of the thumbwheel paddle control assembly arrangement in another actuated position; 
         FIG. 45  is another partial cross-sectional view of an end effector and elongate shaft assembly arrangement; 
         FIG. 46  is an enlarged cross-sectional view of a portion of an articulation joint arrangement and coupler assembly arrangement with an end effector coupled thereto; 
         FIG. 47  is a perspective view of a portion of the handle assembly arrangement with a portion of the handle housing removed; 
         FIG. 48  is an enlarged perspective view of a portion of a handle assembly illustrating a conductor coupling arrangement; 
         FIG. 49  is an exploded perspective view of a portion of another coupler assembly arrangement and articulation joint arrangement; 
         FIG. 50  is a perspective view of another articulation joint arrangement of the present invention; 
         FIG. 51  is an exploded assembly view of the articulation joint arrangement of  FIG. 50 ; 
         FIG. 52  is a cross-sectional view of the articulation joint arrangement of  FIGS. 50 and 51 ; 
         FIG. 53  is another cross-sectional perspective view of the articulation joint arrangement of  FIGS. 50-52 ; 
         FIG. 54  is a perspective view of another articulation joint arrangement of the present invention; 
         FIG. 55  is an exploded assembly view of the articulation joint arrangement of  FIG. 54 ; 
         FIG. 56  is a partial cross-sectional view of the articulation joint arrangement of  FIGS. 54 and 55 ; 
         FIG. 57  is another partial cross-sectional view of the articulation joint arrangement of  FIGS. 54-56 ; 
         FIG. 58  is another partial perspective cross-sectional view of the articulation joint arrangement of  FIGS. 54-57 ; 
         FIG. 59  is another partial perspective cross-sectional view of the articulation joint arrangement of  FIGS. 54-58  with the joint in an articulated orientation; 
         FIG. 60  is another partial perspective cross-sectional view of the articulation joint arrangement of  FIGS. 54-59  with the joint in another articulated orientation; 
         FIG. 61  is a perspective view of another articulation joint arrangement of the present invention; 
         FIG. 62  is another perspective view of the articulation joint arrangement of  FIG. 60  in an articulated orientation; 
         FIG. 63  is an exploded assembly view of the articulation joint of  FIGS. 61 and 62 ; 
         FIG. 64  is a cross-sectional view of the articulation joint arrangement of  FIGS. 61-63 ; 
         FIG. 65  is another cross-sectional perspective view of the articulation joint arrangement of  FIGS. 61-64 ; 
         FIG. 66  is another cross-sectional perspective view of the articulation joint arrangement of  FIGS. 61-65  with the articulation joint in an articulated orientation; 
         FIG. 67  is a perspective view of another motor mounting assembly arrangement of the present invention; 
         FIG. 68  is a front elevational view of the motor mounting assembly arrangement of  FIG. 67 ; 
         FIG. 69  is an exploded assembly view of the motor mounting assembly arrangement of  FIGS. 67 and 68 ; 
         FIG. 70  shows a perspective view of some forms of an electrosurgical end effector for use with the surgical instrument; 
         FIG. 71  shows a perspective view of some forms of the end effector of  FIG. 70  with the jaws closed and the distal end of an axially movable member in a partially advanced position; 
         FIG. 72  is a perspective view of some forms of the axially moveable member of the end effector of  FIG. 70 ; 
         FIG. 73  is a section view of some forms of the end effector of  FIG. 70 ; 
         FIGS. 74-75  illustrates one form of an ultrasonic end effector for use with the surgical instrument; 
         FIGS. 76-77  show additional views of one form of the axially movable member of the end effector of  FIG. 74 ; 
         FIG. 78  illustrates one form of a linear staple end effector that may be used with the surgical instrument; 
         FIG. 79  illustrates one form of a circular staple end effector that may be used with the surgical instrument; 
         FIG. 80  illustrates several example power cords for use with the surgical instrument; 
         FIG. 81  illustrates several example shafts that can be used with the surgical instrument; 
         FIG. 82  is a block diagram of the handle assembly of the surgical instrument showing various control elements; 
         FIG. 83  illustrates one form of various end effector implement portions comprising circuits as described herein; 
         FIG. 84  is a block diagram showing one form of a control configuration to be implemented by the control circuit to control the surgical instrument; 
         FIG. 85  is a flowchart showing one example form of a process flow for implementing the control algorithm of  FIG. 84 ; 
         FIG. 86  is a block diagram showing another form of a control configuration to be implemented by the control circuit to control the surgical instrument; 
         FIG. 87  is a flowchart showing one example form of a process flow for implementing the control algorithm of  FIG. 86 ; 
         FIG. 88  illustrates one form of a surgical instrument comprising a relay station in the handle; 
         FIG. 89  illustrates one form of an end effector with a sensor module configured to transmit a signal disposed therein; 
         FIG. 90  is a block diagram showing one form of a sensor module; 
         FIG. 91  is a block diagram showing one form of a relay station; 
         FIG. 92  is a block diagram showing one form of a relay station configured to convert a received low-power signal; 
         FIG. 93  is a flow chart of one form of a method for relaying a signal indicative of a condition at an end effector; 
         FIG. 94  illustrates a distal portion of an instrument comprising a mechanical stop as illustrated in  FIG. 1  according to certain aspects described herein; 
         FIG. 95  is a diagram of a system adaptable for use with an electromechanical stop comprising a power source, a control system, and a drive motor according to according to certain aspects described herein; 
         FIG. 96  is a graphical illustration depicting change in current over time associated with an instrument comprising an electromechanical stop without a soft stop according to certain aspects described herein; 
         FIG. 97  illustrates a distal portion of an instrument equipped with a mechanical stop comprising a soft stop wherein the drive member is actuated to a position prior to contact with the soft stop at a second position of an end of stroke according to certain aspects described herein; 
         FIG. 98  illustrates the instrument shown in  FIG. 97  wherein the drive member is actuated through the first position of the end of stroke to the second position of the end of stroke according to certain aspects described herein; 
         FIG. 99  is a graphical illustration depicting change in current over time associated with an instrument comprising an electromechanical stop with a soft stop according to certain aspects described herein; 
         FIG. 100  is a perspective view of an alternative motor mounting assembly that employs a gear driven drive mount assembly; 
         FIG. 101  is another perspective view of the motor mounting assembly of  FIG. 100  with the distal shaft housing omitted for clarity; 
         FIG. 102  is another perspective view of the motor mounting assembly of  FIGS. 100 and 101 ; 
         FIG. 103  is a cross-sectional view of the motor mounting assembly of  FIGS. 100-102 ; 
       and 
         FIG. 104  is a top view of the motor mounting assembly of  FIGS. 100-103 . 
         FIG. 105  illustrates one form of a surgical instrument comprising a sensor-straightened end effector in an articulated state. 
         FIG. 106  illustrates the surgical instrument of  FIG. 105  in a straightened state. 
         FIG. 107  illustrates one form of a sensor-straightened end effector inserted into a surgical overtube. 
         FIG. 108  illustrates one form of a sensor-straightened end effector inserted into a surgical overtube in an articulated state. 
         FIG. 109  illustrates one form of a sensor-straightened end effector in an articulated state. 
         FIG. 110  illustrates one form of the sensor-straightened end effector of  FIG. 109  in a straightened state. 
         FIG. 111  illustrates one form of a magnetic ring for use with a sensor-straightened end effector. 
         FIG. 112  illustrates one form of a sensor-straightened end effector comprising a magnetic sensor. 
         FIG. 113  illustrates one form of a magnetic reed sensor. 
         FIG. 114  illustrates one form of a modular motor control platform. 
         FIG. 115  illustrates one form of a modular motor control platform comprising multiple motor-controller pairs. 
         FIG. 116  illustrates one form of a modular motor control platform comprising a master controller and a slave controller. 
         FIG. 117  illustrates one form of a control process implementable by a multiple-motor controlled surgical instrument. 
     
    
    
     DETAILED DESCRIPTION 
     Applicant of the present application also owns the following patent applications that were filed on Mar. 1, 2013, and which are each herein incorporated by reference in their respective entireties:
         U.S. patent application Ser. No. 13/782,375, entitled ROTARY POWERED SURGICAL INSTRUMENTS WITH MULTIPLE DEGREES OF FREEDOM, now U.S. Pat. No. 9,398,911;   U.S. patent application Ser. No. 13/782,323, entitled ROTARY POWERED ARTICULATION JOINTS FOR SURGICAL INSTRUMENTS, now U.S. Pat. No. 9,782,169;   U.S. patent application Ser. No. 13/782,295, entitled ARTICULATABLE SURGICAL INSTRUMENTS WITH CONDUCTIVE PATHWAYS FOR SIGNAL COMMUNICATION, now U.S. Pat. No. 9,700,309;   U.S. patent application Ser. No. 13/782,338, entitled THUMBWHEEL SWITCH ARRANGEMENTS FOR SURGICAL INSTRUMENTS, now U.S. Patent Application Publication No. 2014/0249557;   U.S. patent application Ser. No. 13/782,358, entitled JOYSTICK SWITCH ASSEMBLIES FOR SURGICAL INSTRUMENTS, now U.S. Pat. No. 9,326,767;   U.S. patent application Ser. No. 13/782,499, entitled ELECTROMECHANICAL SURGICAL DEVICE WITH SIGNAL RELAY ARRANGEMENT, now U.S. Pat. No. 9,358,003;   U.S. patent application Ser. No. 13/782,481, entitled SENSOR STRAIGHTENED END EFFECTOR DURING REMOVAL THROUGH TROCAR, now U.S. Pat. No. 9,468,438;   U.S. patent application Ser. No. 13/782,460, entitled MULTIPLE PROCESSOR MOTOR CONTROL FOR MODULAR SURGICAL DEVICE, now U.S. Pat. No. 9,554,794; and   U.S. patent application Ser. No. 13/782,518, entitled CONTROL METHODS FOR SURGICAL INSTRUMENTS WITH REMOVABLE IMPLEMENT PORTIONS, now U.S. Patent Application Publication No. 2014/0246475.       

     Certain exemplary embodiments will now be described to provide 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 embodiments 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 exemplary embodiments and that the scope of the various embodiments of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention. 
     The terms “comprise” (and any form of comprise, such as “comprises” and “comprising”), “have” (and any form of have, such as “has” and “having”), “include” (and any form of include, such as “includes” and “including”) and “contain” (and any form of contain, such as “contains” and “containing”) are open-ended linking verbs. As a result, a surgical system, device, or apparatus that “comprises,” “has,” “includes” or “contains” one or more elements possesses those one or more elements, but is not limited to possessing only those one or more elements. Likewise, an element of a system, device, or apparatus that “comprises,” “has,” “includes” or “contains” one or more features possesses those one or more features, but is not limited to possessing only those one or more features. 
     The terms “proximal” and “distal” are used herein with reference to a clinician manipulating the handle portion of the surgical instrument. The term “proximal” referring to the portion closest to the clinician and the term “distal” referring to the portion located away from the clinician. It will be further appreciated that, for convenience and clarity, spatial terms such as “vertical”, “horizontal”, “up”, and “down” may be used herein with respect to the drawings. However, surgical instruments are used in many orientations and positions, and these terms are not intended to be limiting and/or absolute. 
     Various exemplary 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 elongate shaft of a surgical instrument can be advanced. 
     Turning to the Drawings wherein like numerals denote like components throughout the several views,  FIGS. 1-3  depict a surgical instrument  10  that is capable of applying rotary actuation motions to an implement portion  100  operably coupled thereto. As will be discussed in further detail below, the instrument  10  may be effectively employed with a variety of different implements that may be interchangeably coupled to the instrument  10 . The arrangement of  FIGS. 1 and 2 , for example, is shown coupled to an end effector  102  that is configured to cut and staple tissue. However, other implement arrangements may also be operated by the instrument  10 . 
     End Effector 
     The end effector  102  depicted in  FIGS. 1-6  includes an elongate channel member  110  that may be configured to operably and removably support a staple cartridge  130 . The staple cartridge  130  may include an upper surface or cartridge deck  132  that includes a plurality of staple pockets  134  that are arranged in lines in a staggered fashion on each side of an elongate slot  136 . See  FIG. 3 . A plurality of surgical staples  140  are supported on corresponding staple drivers  138  that are operably supported within the staple pockets  134 . As can also be seen in  FIG. 3 , in one form, the end effector  102  includes an end base  150  that is configured to be coupled to a proximal end of the staple cartridge  130  and seated within a proximal end of the elongate channel  110 . For example, the end base  150  may be formed with distally-extending latch tabs  152  that are configured to be received in corresponding latch slots  142  in the cartridge deck  132 . In addition, the end base  150  may be provided with laterally-extending attachment lugs  154  for attaching the end base  150  to the elongate channel  110 . For example, the attachment lugs  154  may be configured to be received in corresponding attachment holes  112  in the elongate channel  110 . 
     In one form, the end base  150  includes a centrally disposed slot  156  that is configured to support a tissue cutting member  160  and sled  170 . The tissue cutting member  160  may include a body portion  162  that has a tissue cutting portion  164  thereon or otherwise attached thereto. The body portion  162  may be threadably journaled on an end effector drive screw  180  that is rotatably mounted within the elongate channel  110 . The sled  170  is supported for axial travel relative to the end effector drive screw  180  and may be configured to interface with the body portion  162  of the tissue cutting member  160 . As the tissue cutting member  160  is driven distally, the sled  170  is driven distally by the tissue cutting member  160 . As the sled  170  is driven distally, the wedges  172  formed thereon serve to advance the drivers  138  upward within the staple cartridge  130 . 
     The end effector  102  may further include an anvil assembly  190  that is supported for selective movement relative to the staple cartridge  130 . In at least one form, the anvil assembly  190  may comprise a first anvil portion  192  that is coupled to a rear anvil portion  194  and a top anvil portion  196 . The rear anvil portion  194  may have a pair of laterally protruding trunnions  198  that are configured to be received in corresponding trunnions holes or cavities  114  in the elongate channel  110  to facilitate movable or pivotal travel of the anvil assembly  190  relative to the elongate channel  110  and the staple cartridge  130  supported therein. 
     The tissue cutting member  160  may be provided with a pair of laterally-protruding actuator tabs  166  that are configured to be slidably received within slots  199  in the anvil assembly  190 . In addition, the tissue cutting member  160  may further have a foot  168  that is sized to engage a bottom portion of the elongate channel  110  such that, as the tissue cutting member  160  is driven distally, the tabs  166  and foot  168  cause the anvil assembly  190  to move to a closed position. The tabs  166  and foot  168  may serve to space the anvil assembly  190  relative to the staple cartridge  130  at a desired spacing as the tissue is cut and stapled. The first anvil portion  192  may have a staple forming underside  193  thereon to form the surgical staples  140  as they are driven into contact therewith.  FIG. 4  illustrates the position of the anvil assembly  190  and the cutting member  160  when the anvil assembly  190  is in an open position.  FIG. 5  illustrates the position of the anvil assembly  190  and the cutting member  160  after the anvil assembly  190  has been closed, but before the tissue cutting member  160  has been advanced distally or “fired”.  FIG. 6  illustrates the position of the tissue cutting member  160  after it has been advanced to its distal-most position within the staple cartridge  130 . 
     The end effector drive screw  180  may be rotatably supported within the elongate channel  110 . In one form, for example, the end effector drive screw  180  may have a proximal end  182  that is coupled to a drive shaft attachment member  184  that is configured to interface with a coupler assembly  200 . The drive shaft attachment member  184  may be configured to be attached to the proximal end  182  of the end effector drive screw  180 . For example, the drive shaft attachment member  184  may have a hexagonally-shaped protrusion  186  extending therefrom that is adapted to be non-rotatably received in a correspond hexagonal socket that comprises a portion of a firing system generally designated as  500 . Rotation of the end effector drive screw  180  in a first direction causes the tissue cutting member  160  to move in the distal direction. In various forms, the staple cartridge  130  may be fitted with a pair of bumpers  174  that that serve to cushion the sled  170  as it reaches its distal-most position within the elongate channel  110 . The bumpers  174  may each have a spring  176  to provide the bumper with a desired amount of cushion. 
     End Effector Coupler Assembly 
     Various forms of implements  100  may be operably coupled to the surgical instrument  10  by means of a coupler assembly  200 . One form of coupler assembly  200  is shown in  FIGS. 7-14 . The coupler assembly  200  may include a coupler housing segment  202  that is configured to operably support a drive gear assembly collectively designated as  220 . In at least one form, the drive gear assembly  220  includes an input gear  222 , a transfer gear  228 , and an output gear  232 . See  FIG. 8 . The input gear  222  is mounted to or formed on an input shaft  224  that is rotatably supported by first and second bulkhead members  204 ,  206 . The input shaft  224  has a proximal end  226  that is configured to mate with a distal firing shaft segment  510  that comprises a portion of a unique and novel firing system  500  which will be described in further detail below. For example, the proximal end  226  may be configured with a hexagonal cross-sectional shape for non-rotatable insertion into a hexagonal-shaped socket  512  formed in a distal end of a distal firing shaft segment  510 . The transfer gear  228  may be mounted to or formed on a transfer shaft  230  that is rotatably supported by the baffle members  204 ,  206 . The output gear  232  may be mounted to or formed on an output drive shaft  234  that is rotatably supported by the baffle members  204 ,  206 . For assembly purposes, the distal end  236  of the output drive shaft  234  may be configured to be non-rotatably attached to an output socket  238  that protrudes distally out through a distal end cap  210 . In one arrangement, the distal end cap  210  may be attached to the coupler housing  202  by fasteners  208  or any other suitable fastener arrangements. The output socket  238  may be pinned to the distal end  236  of the output drive shaft  234 . The output socket  238  may be configured to non-rotatably mate with the drive shaft attachment member  184 . For example, the output socket  238  may be configured with a hexagonal shape so that it can mate with the hexagonal protrusion  186  on the drive shaft attachment member  184 . In addition, to facilitate operable attachment of the implement  100  to the coupler assembly  200 , an attachment lug may be formed or attached to the end cap  210 . 
     One arrangement of the coupler assembly  200  may further include a locking assembly generally designated as  240 . In at least one form, the locking assembly  240  includes a spring-biased locking member or pin  242  that is movably supported in a locking slot  214  formed in the coupler housing segment  202 . The locking pin  242  may be configured to axially move within the locking slot  214  such that its locking end  244  protrudes out through a hole  211  in the end cap  210 . See  FIG. 8 . A locking spring  246  is journaled on the locking pin  242  to bias the locking pin  242  within the locking slot  214  in the distal direction “DD”. An actuator arm  248  may be formed on or attached to the locking pin  242  to enable the user to apply an unlocking motion to the locking pin  242  in the proximal direction “PD”. 
     As can be seen in  FIGS. 3, 9, and 10 , the elongate channel  110  of the end effector  102  may have a proximal end wall  116  that has a coupling opening  118  formed therein for receipt of the attachment lug  212  therein. In one arrangement, for example, the attachment lug  212  may include a neck portion  213  that has a mushroomed attachment head  215  formed thereon. The coupling opening  118  may have a first circular portion  120  sized to enable the attachment head  215  to be inserted therein. The coupling opening  118  may further have a narrow slot  122  formed therein that is sized to enable the neck  213  to be received therein. The proximal end wall  116  may further have a locking hole  124  for receiving the distal end  244  of the locking pin  242  therein. 
     One method of attaching an end effector  102  to the coupling assembly  200  of the surgical instrument  10  may be understood from reference to  FIGS. 12-14 . For example, to attach the end effector  102  to the coupling assembly  200 , the user may align the hexagonal protrusion  186  on the drive shaft attachment member  184  with the hexagonal output socket  238 . Likewise, the mushroom head  215  may be aligned with the circular opening portion  120  of the coupling opening  118  as illustrated in  FIGS. 9 and 12 . The user may then axially insert the protrusion  186  into the socket  238  and the attachment head  215  into the coupling opening  118  as shown in  FIG. 13 . Thereafter, the user may rotate the end effector  102  (represented by arrow “R” in  FIG. 14 ) to cause the neck  213  to enter the slot  122  and enable the distal end  244  of the locking pin  242  to snap into the locking hole  124  to prevent further relative rotation between the end effector  102  and the coupling assembly  200 . Such arrangement serves to operably couple the end effector  102  to the surgical instrument  10 . 
     To detach the end effector  102  from the coupling assembly  200 , the user may apply an unlocking motion to the actuator arm  246  to bias the locking pin the proximal direction “PD”. Such movement of the locking pin  242  causes the distal end  244  of the locking pin  242  to move out of the locking hole  124  in the end wall  116  of the elongate channel  110 . The user is then free to rotate the end effector  102  relative to the coupling assembly in an opposite direction to move the neck portion  213  of the attachment button  212  out of the slot  122  to enable the attachment head  215  to be axially pulled out of the coupling opening  118  in the end effector  102  to thereby detach the end effector  102  from the coupling assembly  200 . As can be appreciated from above, the coupling assembly  200  provides a unique and novel arrangement for operably coupling a surgical implement  100  that is operable through application of rotary drive motion(s) to the surgical instrument  10 . In particular, the coupling assembly  200  enables a variety of different surgical implements  100  or end effectors  102  to be operably coupled to the elongate shaft assembly  30  of the surgical instrument  10 . 
     Articulation System 
     As can be seen in  FIGS. 1 and 2 , the elongate shaft assembly  30  may define a shaft axis A-A. In at least one form, the elongate shaft assembly  30  may include an articulation system  300  for selectively articulating the end effector  102  about an articulation axis B-B that is substantially transverse to the shaft axis A-A. One form of articulation system  300  is shown in  FIGS. 15 and 16 . As can be seen in those Figures, the articulation system  300  may include a powered articulation joint  310 . In at least one arrangement, the articulation joint  310  includes a distal joint portion or a distal clevis  312  that is rotatably supported on a proximally-extending hub portion  203  of the coupler housing segment  202  by a distal housing bearing  314 . See  FIG. 20 . The distal clevis  312  may be pivotally attached to a proximal joint portion or proximal clevis  330  by an articulation pin  332  that defines articulation axis B-B. See  FIG. 18 . The distal clevis  312  may include a distally-protruding attachment hub  316  that is sized to be received within the proximal end of the coupler housing segment  202 . The attachment hub  316  may have an annular groove  318  therein that is configured to receive attachment pins  320  therein. See  FIG. 8 . The attachment pins  320  serve to attach the coupler housing segment  202  to the distal clevis  312  such that the coupler housing segment  202  may rotate relative to the distal clevis  312  about the shaft axis A-A. As can be seen in  FIG. 20 , the distal firing shaft segment  510  extends through the hub portion  203  of the coupler housing segment  202  and is rotatably supported relative thereto by a distal firing shaft bearing  322  mounted within the hub portion  203 . 
     To facilitate the application of a rotary drive or firing motion to the end effector  102 , as well as to facilitate rotation of the end effector  102  relative to the elongate shaft  30  about the shaft axis A-A while maintaining the ability to articulate the end effector  102  relative to the elongate shaft assembly  30  about articulation axis B-B, the articulation joint  310  may include a unique and novel “nested” gear assembly, generally designated as  350  and which is located within a gear area  351  between the distal clevis  312  and the proximal clevis  330 . See  FIGS. 18-20 . In at least one form, for example, the nested gear assembly  350  may include an inner drive shaft gear train or “first gear train”  360  that is “nested” with an outer end effector gear train or “second gear train”  380 . As used herein, the term “nested” may mean that no portion of the first gear train  360  extends radially outward beyond any portion of the second gear train  380 . Such unique and novel gear arrangement is compact and facilitates the transfer of rotary control motions to the end effector while also enabling the distal clevis portion to pivot relative to the proximal clevis portion. As will be discussed in further detail below, the inner drive shaft gear train  360  facilitates the application of rotary drive or firing motions from a proximal firing shaft segment  520  to the distal firing shaft segment  510  through the articulation joint  310 . Likewise, the outer end effector gear train  380  facilitates the application of rotary control motions to the coupler assembly  200  from an end effector rotation system  550  as will be discussed in further detail below. 
     In at least one form, for example, the inner drive shaft gear train  360  may include a a distal drive shaft bevel gear  362  that may be attached to the proximal end of the distal firing shaft segment  510  by a screw  364 . See  FIG. 17 . The inner drive shaft gear train  360  may also include a proximal drive shaft bevel gear  366  that is attached to the proximal firing shaft segment  520  by a screw  368 . See  FIG. 20 . In addition, the inner drive shaft gear train  360  may further include a drive shaft transfer gear  370  that is mounted on a transfer gear bearing  374  that is mounted on a transverse gear shaft  372 . See  FIG. 17 . Such inner drive shaft gear train  360  may facilitate the transfer of rotary drive motions from the proximal firing shaft segment  520  through the articulation joint  310  to the distal firing shaft segment  510 . 
     As indicated above, the nested gear assembly  350  also includes an outer end effector gear train  380  that facilitates the application of rotary control motions to the coupler assembly  200  from the end effector rotation system  550  through the articulation joint  310 . In at least one form, the outer end effector gear train  380  may, for example, include an output bevel gear  382  that is non-rotatably (e.g., keyed) onto the proximally-extending hub portion  203  of the coupler housing segment  202 . The outer end effector gear train  380  may further include an input bevel gear  384  that is non-rotatably attached (e.g., keyed onto) to a proximal rotation shaft segment  552  of the end effector rotation system  550 . In addition, the outer end effector gear train  380  may further include a rotation shaft transfer gear  388  that is mounted on an outer transfer gear bearing  386  that is supported on the transversely-extending articulation pin  332 . See  FIG. 17 . Articulation pin  332  extends through the hollow transverse gear shaft  372  and serves to pin the distal clevis  312  to the proximal clevis  330  for articulation about the transverse articulation axis B-B. The articulation shaft  332  may be retained in position by spring clips  334 . The unique and novel articulation joint  310  and nested gear assembly  350  facilitate the transfer of various control motions from the handle assembly  20  through the elongate shaft assembly  30  to the end effector  102  while enabling the end effector  102  to rotate about the elongate shaft axis A-A and articulate about the articulation axis B-B. 
     Articulation of the end effector  102  about the articulation axis B-B relative to the elongate shaft assembly  30  may be accomplished by an articulation control system  400 . In various forms, the articulation control system  400  may include an articulation control motor  402  that is operably supported in the handle assembly  20 . See  FIG. 15 . The articulation control motor  402  may be coupled to an articulation drive assembly  410  that is operably supported on a detachable drive mount  700  that is removably supported in the handle assembly  20  as will be discussed in further detail below. In at least one form, the articulation drive assembly  410  may include a proximal articulation drive shaft segment  412  that is rotatably supported in a shaft housing assembly  710  of the detachable drive mount  700 . See  FIGS. 27 and 28 . For example, the proximal articulation drive shaft segment  412  may be rotatably supported within a distal shaft housing portion  712  by articulation bearings  414 . In addition, the proximal articulation drive shaft segment  412  may be rotatably supported in a proximal shaft housing portion  714  by bearings  415 . See  FIG. 28 . The articulation control system  400  may further comprise a proximal articulation shaft segment  420  that is rotatably driven about the shaft axis A-A by the articulation control motor  402 . As can also be seen in  FIG. 15 , the articulation drive assembly  410  may also include a pair of articulation drive pulleys  416 ,  417  that serve to drive articulation drive belt  418 . Thus, actuation of the articulation control motor  402  may result in the rotation of the proximal articulation shaft segment  420  about the shaft axis A-A. See  FIG. 15 . 
     As can be seen in  FIGS. 15 and 16 , the proximal articulation shaft segment  420  has a threaded portion  422  that is adapted to threadably mate with an articulation drive link  424 . Rotation of the distal articulation drive shaft segment  420  in a first direction may axially drive the articulation drive link  424  in the distal direction “DD” and rotation of the distal articulation drive shaft segment  420  in an opposite or second direction may cause the articulation drive link  424  to move axially in the proximal direction “PD”. The articulation drive link  424  may be pinned to an articulation bar  426  by a pin  428 . The articulation bar  426  may, in turn, be pinned to the distal clevis  312  by pin  429 . See  FIG. 17 . Thus, when the clinician wishes to articulate the end effector  102  or implement  100  about the articulation axis B-B relative to the elongate shaft assembly  30 , the clinician actuates the articulation control motor  402  to cause the articulation control motor  402  to rotate the proximal articulation shaft segment  420  to thereby actuate the articulation bar  426  in the desired direction to pivot the distal clevis  312  (and end effector  102  attached thereto) in the desired direction. See  FIGS. 21 and 22 . 
     Firing System 
     As indicated above, the end effector  102  may be operated by rotary controlled motions applied to the end effector drive screw  180  by a firing system  500  which includes the distal firing shaft segment  510  and the proximal firing shaft segment  520 . See  FIG. 23 . The proximal firing shaft segment  520  comprises a portion of the elongate shaft assembly  30  and may be rotatably supported within a hollow proximal rotation shaft segment  552  by a distal bearing sleeve  522 . See  FIG. 20 . Referring again to  FIG. 23 , in at least one form, the firing system  500  includes a firing motor  530  that is operably supported in the handle assembly  20 . A proximal end of the proximal firing shaft segment  520  may be rotatably supported within the detachable drive mount  700  and be configured to be coupled to the firing motor  530  in a manner discussed in further detail below. As can be seen in  FIG. 30 , the proximal end of the proximal firing shaft segment  520  may be rotatably supported in a thrust bearing  524  mounted with the distal bulkhead plate  722  of the drive mount bulkhead assembly  720 . Actuation of the firing motor  530  will ultimately result in the rotation of the end effector drive screw  180  to apply the rotary control motion to the end effector  102 . 
     End Effector Rotation System 
     In various forms, the surgical instrument  10  may also include an end effector rotation system or “distal roll system”  550  for selectively rotating the end effector  102  relative to the elongate shaft assembly  30  about the shaft axis A-A. The end effector rotation system  550  may include the proximal rotation shaft segment  552  which also comprises a portion of the elongate shaft assembly  30 . As can be seen in  FIG. 20 , the proximal rotation shaft segment  552  may be rotatably supported within the proximal clevis  330  by a distal bearing  554  and a proximal bearing  556 . In addition, the proximal rotation shaft segment  552  may be rotatably supported within the proximal articulation shaft segment  420  by a distal bearing sleeve  558  and a proximal bearing  559 . See  FIGS. 20 and 30 . The proximal end of the proximal rotation shaft segment  552  may also be rotatably supported within a drive mount bulkhead assembly  720  by a proximal bearing  555  as can be seen in  FIG. 30 . 
     In at least one form, the end effector rotation system  550  may include an end effector rotation or “distal roll” motor  560  that is operably supported in the handle assembly  20 . See  FIG. 24 . The end effector rotation motor  560  may be coupled to a rotation drive assembly  570  that is operably supported on the detachable drive mount  700 . In at least one form, the rotation drive assembly  570  includes a proximal rotation drive shaft segment  572  that is rotatably supported in the shaft housing assembly  710  of the detachable drive mount  700 . See  FIG. 27 . For example, the proximal rotation drive shaft segment  572  may be rotatably supported within the distal shaft housing portion  712  by bearings  576 . In addition, the proximal rotation drive shaft segment  572  is rotatably supported in the proximal housing portion  714  by bearing  577 . See  FIG. 28 . As can be seen in  FIGS. 24 and 28 , the rotation drive assembly  570  may also include a pair of rotation drive pulleys  574 ,  575  that serve to drive a rotation drive belt  578 . Thus, actuation of the end effector rotation motor  560  will result in the rotation of the proximal rotation shaft segment  552  about the shaft axis A-A. Rotation of the proximal rotation shaft segment  552  results in rotation of the coupler assembly  200  and ultimately of the end effector  102  coupled thereto. 
     Shaft Rotation System 
     Various forms of the surgical instrument  10  may also include a shaft rotation system generally designated as  600 . The shaft rotation system may also be referred to herein as the “proximal roll system”. In at least one form, the shaft rotation system  600  includes a proximal outer shaft segment  602  that also comprises a portion of the elongate shaft assembly  30 . The proximal outer shaft segment  602  has a distal end  604  that is non-rotatably coupled to the proximal clevis  330 . As can be seen in  FIGS. 19 and 26 , the distal end  604  has a clearance notch  606  therein for permitting actuation of the articulation bar  426  relative thereto. The shaft rotation system  600  may include a shaft rotation or “proximal roll” motor  610  that is operably supported in the handle assembly  20 . The shaft rotation motor  610  may be coupled to a shaft drive assembly  620  that is operably supported on the detachable drive mount  700 . In at least one form, the shaft drive assembly  620  includes a proximal drive shaft segment  622  that is rotatably supported in the distal shaft housing portion  712  of the detachable drive mount  700  by bearings  624 . See  FIG. 28 . In addition, the proximal drive shaft segment  622  is rotatably supported in the proximal drive shaft housing portion  714  by bearing  626 . As can be seen in  FIGS. 26 and 28 , the shaft drive assembly  620  may also include a pair of rotation drive pulleys  630 ,  632  that serve to drive a shaft drive belt  634 . The drive pulley  632  is non-rotatably attached to the proximal drive shaft segment  602  such that rotation of the drive pulley  632  results in rotation of the proximal drive shaft segment  602  and the end effector  102  attached thereto about the shaft axis A-A. As can be further seen in  FIGS. 28 and 30 , the proximal drive shaft segment  602  is rotatably supported within the distal shaft housing portion  712  by a pair of sleeve bearings  607  and  608 . 
     The unique and novel articulation system arrangements of the present invention afford multiple degrees of freedom to the end effector while facilitating the application of rotary control motions thereto. For example, in connection with some surgical operations, positioning of the end effector into a position that is coplanar with the target tissue may be necessary. Various arrangements of the present invention offer at least three degrees of freedom to an end effector while meeting size limitations often encountered when performing surgical procedures laparoscopically, for example. 
     Various forms of the present surgical instrument facilitate improved user dexterity, precision, and efficiency in positioning the end effector relative to the target tissue. For example, conventional shaft articulation joints commonly used for power transmission frequently employ universal joints(s), hinged vertebral and flexurally compliant couplings. All of those methods may tend to suffer from performance limitations including limits in bend radius and excessive length characteristics. Various forms of the unique and novel elongate shaft assemblies and drive systems disclosed herein, for example, allow the distance between the articulation axis and the end effector to be minimized when compared to other conventional articulation arrangements. The elongate shaft assemblies and articulation joint arrangements disclosed herein facilitate transfer of at least one rotary control motion to the end effector while also affording multiple degrees of freedom to the end effector to enable the end effector to be precisely positioned relative to the target tissue. 
     After the end effector  102  or implement  100  has been used, it may be detached from the coupler assembly  200  of the surgical instrument  10  and either disposed of or separately reprocessed and sterilized utilizing appropriate sterilization methods. The surgical instrument  10  may be used multiple times in connection with fresh end effectors/implements. Depending upon the particular application, it may be desirable for the surgical instrument  10  to be resterilized. For example, the instrument  10  may be resterilized before it is used to complete another surgical procedure. 
     Surgical instruments must be sterile prior to use. One popular method for sterilizing medical devices involves exposing the device to wet steam at a desired temperature for a desired time period. Such sterilization procedures, while effective, are generally ill-suited for sterilizing surgical instruments that employ electrical components due to the high temperatures generated when using steam sterilization methods. Such devices are commonly sterilized by exposing them to a gas such as, for example, Ethylene Oxide. 
     Various forms of the surgical instrument  10  may be sterilized utilizing conventional sterilization methods. In at least one form, for example, the elongated shaft assembly  30  may be fabricated from components and materials that may be effectively sterilized utilizing methods that employ relatively high sterilization temperatures. It may be desirable, however, to use sterilization methods that have lower operating temperatures when sterilizing the handle assembly, for example, to avoid possibly damaging the electrical components. Thus, it may be desirable to sterilize the handle assembly  20 , which houses various electrical components, apart from the elongate shaft assembly  30 . To facilitate use of such separate sterilization procedures, the elongate shaft assembly  30 , in at least one form, is detachable from the handle assembly  20 . 
     Detachable Drive Mount Assembly 
     More specifically and with reference to  FIG. 28 , the detachable drive mount assembly  700  is operably supported within a portion of the handle assembly  20 . In one form, for example, the detachable drive mount assembly  700  may be mounted within distal handle housing segments  21  and  22  that may be interconnected by means of snap features, screws or other fastener arrangements. The distal handle housing segments  21  and  22  when coupled together may be referred to herein as a “distal handle housing portion” or “housing”  25 . The detachable drive mount assembly  700  may, for example, include a shaft housing assembly  710  that comprises a distal shaft housing  712  and a proximal shaft housing  714 . The detachable drive mount assembly  700  may further comprise a drive mount bulkhead assembly  720  that includes a distal bulkhead plate  722  and a proximal coupler bulkhead plate  724 . As was described above, in at least one form, the detachable drive mount assembly  700  may operably support the articulation drive assembly  410 , the proximal end of the proximal firing shaft segment  520 , the rotation drive assembly  570 , and the shaft drive assembly  620 . To facilitate quick coupling of the firing shaft segment  520 , the articulation drive assembly  410 , the rotation drive assembly  570 , and the shaft drive assembly  620  to the firing motor  530 , the articulation control motor  402 , the end effector rotation motor  560  and the shaft rotation motor  610 , respectively, a unique and novel coupler arrangement may be employed. 
     Motor Mounting Assembly 
     In at least one form, for example, the detachable drive mount assembly  700  may be configured to be removably coupled to a motor mounting assembly generally designated as  750 . The motor mounting assembly  750  may be supported within handle housing segments  23  and  24  that are couplable together by snap features, screws, etc. and serve to form a pistol grip portion  26  of the handle assembly  20 . See  FIG. 1 . The handle housing segments  23  and  24 , when coupled together, may be referred to herein as a “proximal handle housing portion” or “housing”  28 . Referring to  FIGS. 29-32 , the motor mounting assembly  750  may comprise a motor mount  752  that is removably supported within the handle housing segments  23  and  24 . In at least one form, for example, the motor mount  752  may have a bottom plate  754  and a vertically extending motor bulkhead assembly  756 . The bottom plate  754  may have a fastener tab  758  formed thereon that is configured to retainingly mate to be received with a bottom plate portion  730  of the detachable drive mount  700 . In addition, a right locator pin  772  and a left locator pin  774  are mounted in the motor bulkhead assembly  756  and protrude distally therethrough in corresponding right and left socket tubes  716 ,  718  formed in the proximal shaft housing portion  714 . See  FIG. 32 . 
     In at least one configuration, the detachable drive mount assembly  700  may be removably coupled to the motor mounting assembly  750  by releasable latch arrangements  760 . As can be seen in  FIG. 31 , for example, a releasable latch arrangement  760  may be located on each lateral side of the motor mounting assembly  750 . Each releasable latch arrangement  760  may include a latch arm  762  that is pivotally attached to the motor bulkhead assembly  756  by a corresponding pin  764 . Each latch arm  762  may protrude out through a corresponding fastener lug  766  formed on the distal side of the motor bulkhead assembly  756 . The fastener lugs  766  may be configured to be slidably received within corresponding receiver members  726  that protrude proximally from the proximal coupler bulkhead plate  724 . See  FIGS. 30 and 32 . When the drive mount assembly  700  is brought into mating engagement with the motor mounting assembly  750 , the fastener lugs  766  are slid into the corresponding receiver members  726  such that the latch arms  762  retainingly engage a latch portion  728  of the corresponding receiver member  726 . Each latch arm  762  has a corresponding latch spring  768  associated therewith to bias the latch arm  762  into retaining engagement with the corresponding latch portion  728  to retain the detachable drive mount assembly  700  coupled to the motor mounting assembly  750 . In addition, in at least one form, each latch arrangement  760  further includes a release button  770  that is movably coupled to the motor bulkhead  756  and is oriented for selective contact therewith. Each release button  770  may include a release spring  771  that biases the button  770  out of contact with its corresponding latch arm  762 . When the clinician desires to detach the detachable drive mount assembly  700  from the motor mounting assembly  750 , the clinician simply pushes each button  770  inwardly to bias the latch arms  762  out of retaining engagement with the latch portions  728  on the receiver members  726  and then pulls the detachable drive mount assembly  700  out of mating engagement with the motor mounting assembly  750 . Other releasable latch arrangements may be employed to releasably couple the detachable drive mount assembly  700  may be removably coupled to the motor mounting assembly  750 . 
     At least one form of the surgical instrument  10  may also employ coupler assemblies for coupling the control motors to their respective drive assemblies that are operably supported mounted on the detachable drive mount  700 . More specifically and with reference to  FIGS. 28-32 , a coupler assembly  780  is employed to removably couple the articulation drive assembly  410  to the articulation control motor  402 . The coupler assembly  780  may include a proximal coupler portion  782  that is operably coupled to the drive shaft  404  of articulation control motor  402 . In addition, the coupler assembly  780  may further include a distal coupler portion  784  that is attached to the proximal articulation drive shaft  412 . See  FIGS. 28 and 32 . Each distal coupler portion  784  may have a plurality of (three are shown) coupler protrusions  786  that are designed to non-rotatably seat with corresponding scalloped areas  788  formed in the proximal coupler portion  782 . See  FIG. 30 . Similarly, another distal coupler portion  784  may be attached to the proximal rotation drive shaft  572  of the rotation drive assembly  570  and a corresponding proximal coupler portion  782  is attached to the rotation motor drive shaft  562 . In addition, another distal coupler portion  784  may be attached to the proximal firing shaft segment  520  and a corresponding proximal coupler portion  782  is attached to the firing motor drive shaft  532 . Still another distal coupler portion  784  may be attached to the proximal drive shaft segment  622  of the shaft drive assembly  620  and a corresponding proximal coupler portion  782  is attached to the drive shaft  612  of the shaft rotation motor  610 . Such coupler assemblies  780  facilitate coupling of the control motors to their respective drive assemblies regardless of the positions of the drive shafts and the motor shafts. 
     The various forms of the unique and novel handle assembly arrangement described above enable the elongate shaft assembly  30  to be easily detached from the remaining portion of the handle assembly  20  that houses the motors  402 ,  530 ,  560  and  610  and the various electrical components comprising a control system, generally designated as  800 . As such, the elongate shaft assembly  30  and the detachable drive mount portion  700  may be sterilized apart from the remaining portion of handle assembly housing the motors and control system which may be damaged utilizing sterilization methods that employ high temperatures. Such unique and novel detachable drive mount arrangement may also be employed in connection with arrangements wherein the drive system (motors and control components) comprise a portion of a robotic system that may or may not be hand held. 
     Gear Driven Drive Mount Arrangement 
       FIGS. 100-103  illustrate an alternative drive mount  5700  that employs a collection of gear drives for transmitting drive motions from the motors to their respective shafts. As can be seen in  FIG. 100 , the drive mount  5700  may include a distal shaft housing assembly  5710  that includes a distal shaft housing  5712  that operably supports a plurality of gear train arrangements. The distal shaft housing  5712  is configured to be removably mounted to the proximal coupler bulkhead plate  5724  that has a pair of mounting sockets  5725  for receiving corresponding mounting lugs  5713  protruding from the distal shaft housing  5712  as can be seen in  FIG. 100 . As in the above described arrangements, the shaft of the firing or transection motor  530  is directly coupled to the proximal firing shaft segment  5520  by a coupler assembly  5780  as can be seen in  FIG. 103 . The proximal rotational shaft segment  5552  of the end effector rotation system  550  is rotated by a gear train, generally depicted as  5565 . In at least one form, for example, the gear train  5565  includes a driven gear  5566  that is attached to the proximal rotational shaft segment  5552  and is supported in meshing engagement with a drive gear  5567 . As can be most particularly seen in  FIG. 103 , the drive gear  5567  is mounted to a spur shaft  5568  that is rotatably supported in the distal shaft housing  5712 . The spur shaft  5568  is coupled to the shaft of the end effector rotation or distal roll motor  560  by a coupler assembly  5780 . 
     The proximal articulation shaft segment  5420  is rotated by a gear train, generally depicted as  5430 . In at least one form, for example, the gear train  5430  includes a driven gear  5432  that is attached to the proximal articulation shaft segment  5420  and is supported in meshing engagement with a drive gear  5434 . As can be most particularly seen in  FIG. 102 , the drive gear  5434  is mounted to a spur shaft  5436  that is rotatably supported in the distal shaft housing  5712 . The spur shaft  5436  is coupled to the shaft of the articulation control motor  402  by a coupler assembly  5780 . 
     The proximal outer shaft segment  5602  is rotated by a gear train, generally depicted as  5640 . In at least one form, for example, the gear train  5640  includes a driven gear  5642  that is attached to the proximal outer shaft segment  5602  and is supported in meshing engagement with a compound bevel gear  5644  that is rotatably supported within the distal shaft housing  5712 . The compound bevel gear  5644  is in meshing engagement with a drive bevel gear assembly  5646  that is mounted to a spur shaft  5648  that is also rotatably supported in the distal shaft housing  5712 . The spur shaft  5648  is coupled to the shaft of the shaft rotation or proximal roll motor  610  by a coupler assembly  5780 . See  FIG. 101 . The alternative drive mount  5700  motors and gear trains may be used to power and control the surgical instrument in the manners herein described. 
     Power and Control Systems 
     In various forms, the surgical instrument  10  may employ a control system generally designated as  800  for controlling the various motors employed by the instrument. The motors  402 ,  530 ,  560  and  610  and their related control components may also be referred to herein as a “drive system”, generally designated as  398 . In one form, the drive system  398  serves to “electrically generate” a plurality of control motions. The term “electrically generate” refers to the use of electrical signals to actuate a motor or other electrically powered device and may be distinguished from control motions that are manually or otherwise mechanically generated without the use of electrical current. In one form, the drive system  398  may be operably supported within a handle assembly that may be held in the hand or hands of the clinician. In other forms, however, the drive system  398  may comprise a part of and/or be operated by and/or be supported by a robotic system. 
     In one form, the motors  402 ,  530 ,  560  and  610  and their related control components may receive power from a battery  802  that is housed within the pistol grip portion  26  of the handle assembly  20 . In other arrangements, the battery may be supported by a robotic system, for example. In other embodiments, however, the handle assembly  20  may have a power cord (not shown) protruding therefrom for supplying power from another source electrical power. In still other arrangements, the motors and electrical components may receive power and control signals from a robotic system. The control system  800  may comprise various control system components that may include, for example, a distal circuit board  810  that is supported on the detachable drive mount  700 . The distal circuit board  810  may include electrical connectors  812  and/or electrical components that can be sterilized utilizing conventional steam sterilization techniques as well as by other lower temperature sterilization methods. The control system  800  may further include a proximal circuit board  820  that is supported in the portion of the handle assembly  20  formed by the handle housings segments  23  and  24 . The proximal circuit board  820  is configured to be electrically coupled to the distal circuit board  810  when the detachable drive mount  700  has been coupled to the motor mounting assembly  750 . 
     Various forms of the surgical instrument  10  may employ a unique and novel control switch arrangement  830  that may be operably housed within or supported by the pistol grip portion  26  of the handle assembly  20 . For example, in at least one form, the control switch arrangement  830  may include a unique and novel joystick control  840  that enables the user to maximize functional control of various aspects of the surgical instrument  10  through a single interface. More specifically and with reference to  FIGS. 33-39 , one form of joystick control  840  may include a joystick control rod  842  that is operably attached to a joystick switch assembly  850  that is movably housed within a switch housing assembly  844 . The switch housing assembly  844  may be mounted within the pistol grip portion  26  of the handle assembly  20 . In at least one form, for example, the switch housing assembly  844  may include a housing body  846  and a rear housing plate  848 . As can be most particularly seen in  FIGS. 35-39 , a joystick printed circuit board  852  may be operably supported on the joystick switch assembly  850  by a rear mounting plate  854 . The rear mounting plate  854  may be configured to move as a unit with the joystick switch assembly  850  and joystick printed circuit board  852  within the switch housing  844 . A joystick spring  856  may be supported between the rear housing plate  848  and the rear mounting plate  854  to bias the joystick switch assembly  850  and joystick control rod  842  in the forward or distal direction. See  FIGS. 36 and 38 . 
     The joystick control  840  may be electrically coupled to the proximal circuit board  820  and battery  802  of the control system  800  through various connector cables  864  for providing control power to the various motors  402 ,  530 ,  560 , and  610  of the surgical instrument  10 . For example, by rocking or otherwise actuating the joystick control rod  842 , the user may control the articulation control motor  402  and/or the distal roll motor  560  and/or the proximal roll motor  610 . 
     The joystick control switch assembly  850  may be referred to herein as a “first switch” for controlling one or more of the motors of the drive system. The joystick control  840  may further include a first sensor  860  which may comprise, for example, a magnet, that may be mounted to the joystick printed circuit board  852  for movable travel therewith. In addition, a second or stationary sensor  862  may be mounted within the rear housing plate  848 . The second sensor  862  may comprise, for example, a “hall effect” sensor or similar sensing device. In at least one arrangement for example, the sensor  862  may be configured to communicate with the firing motor  530 . The first and second sensors,  860 ,  862  may be referred to herein as a “second switch” generally designated as  858 . The above-described arrangement allows the joystick switch assembly  850  to axially move in and out when the user depresses the joystick control rod  842 . By leveraging the in and out motion of the entire joystick switch assembly  850 , in at least one form, the design essentially consists of a switch within a switch. In an unactuated position, the joystick spring  856  biases the joystick switch assembly  850  in the forward (distal) direction. When the clinician pushes the joystick  842  inwardly (proximally), the first sensor  860  is moved closer to the second sensor  862 . Moving the first sensor  860  closer to the second sensor  862  may result in the actuation of the so-called second switch  858  which may result in the actuation of the transection or firing motor  530 . 
     When performing a procedure using an end effector  102 , the clinician may wish to open and close the anvil assembly  190  to manipulate the target tissue into a desired position without transecting or cutting the tissue. In one form, as the clinician initially depresses the joystick control rod  842 , the second switch  858  causes the firing motor  530  to be activated to thereby cause the tissue cutting member  160  to start to move distally. In various forms, the tissue cutting member  160  is arranged within the end effector  102  such that initial movement of the tissue cutting member  160  in the distal direction causes the anvil assembly  190  to close (i.e., pivot toward the staple cartridge  130  without cutting the tissue or firing the surgical staples). When the clinician releases the joystick control rod  842 , the joystick spring  856  will bias the joystick assembly  850  distally to thereby move the first sensor  860  away from the second sensor  862 . Movement of the sensor  860  away from the second sensor  862  may reduce the rotational speed of the firing motor  530  until the firing motor  530  is eventually stopped or deactivated. In at least one form, this second switch arrangement  858  may be configured such that the rotational speed of the firing motor  530  is directly proportional to the speed at which the user depresses the joystick control rod  842 . 
     Once the clinician has positioned and captured the desired tissue within the end effector  102 , the end effector  102  may be actuated or “fired” by fully depressing the joystick control rod  842 . In various forms, the joystick switch assembly  850  may also have a third compression switch  866  integrally formed therein and which also communicates with the control system  800 . Full depression of the joystick control rod  842  may result in the activation of the third switch  866 . In at least one form, when the third switch  866  is activated, the firing motor  530  will remain activated even when the clinician releases the joystick control rod  842 . After the firing stroke has been completed (i.e., the tissue cutting member  160  has been driven to its distal-most position in the end effector  102 ), the user may again fully depress the joystick control rod  842  to release the third switch  866  and thereby return control of the firing motor  530  to the second switch  858 . Thus, if the clinician releases the joystick control rod  842  after completely depressing it for the second time, the joystick spring  856  will bias the joystick switch assembly  850  to the starting position. The control system  800  will cause the firing motor  530  to rotate in an opposite direction until the tissue cutting member  160  has been returned to its starting position whereby the anvil assembly  190  is once again moved to an open position to enable the end effector  102  to release the transected tissue. 
     In various forms, the switch arrangement  830  may also employ a unique and novel thumbwheel control assembly  870 . As can be seen in  FIG. 42 , the thumbwheel control assembly  870  may be rotatably mounted on a distally protruding hub portion  845  of the switch housing assembly  844  such that the thumbwheel control assembly  870  is pivotable about a switch axis SA-SA. Such position conveniently places a thumbwheel actuator member  872  of the thumbwheel control assembly  870  in a position wherein the clinician can pivot it with a thumb and/or index finger while grasping the pistol grip portion  26  of the handle assembly  20 . The thumbwheel actuator member  872  may be attached to a thumbwheel collar  874  that is received on the hub portion  845  and may be rotatably retained in position by a mounting flange  27  formed by the handle segments  23  and  24 . A left sensor (magnet)  876  and a right sensor (magnet)  878  are mounted to the thumbwheel collar  874  as shown in  FIG. 41 . The sensors  876  and  878  may have opposing polarities. A stationary sensor  880  may be mounted to the switch housing assembly  844  such that it is centrally disposed between the left sensor  876  and the right sensor  878 . The stationary sensor  880  may comprise, for example, a “hall effect” sensor and be coupled to the proximal circuit board  820  of the control system  800  for controlling one of the control motors. For example, the thumbwheel control assembly  870  may be used to control, for example, the proximal roll or shaft rotation motor  610 . In other arrangements, the thumbwheel control assembly  870  may be used to control the distal roll motor  560  to rotate the end effector about the shaft axis relative to the elongate shaft assembly. A pair of centering springs  882  may be employed to bias the thumbwheel collar  874  into a central or neutral position. When the thumbwheel collar  874  is in the neutral position as shown in  FIG. 41 , the shaft rotation or proximal roll motor  610  (or distal roll motor  560 —whichever the case may be) is deactivated. 
     As the user pivots the thumbwheel actuator  872  in a clockwise direction to a position shown in  FIG. 43 , the control system  800  may cause the shaft rotation motor  610  to rotate the elongate shaft assembly  30  about the shaft axis A-A in a clockwise direction. Likewise, when the user pivots the thumbwheel actuator  872  in a counterclockwise direction to the position shown in  FIG. 44 , the control system  800  may cause the shaft rotation motor  610  to rotate the elongate shaft assembly  30  in the counterclockwise direction about the shaft axis A-A. Stated another way, as the user pivots the thumbwheel actuator  872  clockwise or counterclockwise, the stationary sensor  880  controls the rotational direction of the elongate shaft assembly  30  based upon the proximity of the left and right sensors  876 ,  878  in relationship to the stationary sensor  880 . The response of the stationary sensor  880  can be configured so that, as the user increases rotation of the thumbwheel actuator  872 , the relative speed that the motor  610  rotates the elongate shaft assembly  30  increases. As can be seen in  FIGS. 41-44 , a stop lug  847  may be formed on the switch housing assembly  844  to cooperate with a notch  875  in the thumbwheel collar to prevent contact between the movable sensors  876 ,  878  and the stationary sensor  880 . Those of ordinary skill in the art will understand that the thumbwheel control assembly  870  may be used to control any of the other motors of the surgical instrument  10 . Similarly, the joy stick control  840  may be configured to control any one or more of the motors in the surgical instrument  10 . The unique and novel thumbwheel control assembly arrangements disclosed herein enable the user to have functional control through rotation of an ergonomic thumbwheel actuator interface. In alternative forms, the movable sensors  876 ,  878 , may comprise hall effector sensors that each communicate with the motor. The stationary sensor  880  may comprise a magnet. 
     In various forms, each of the motors of the surgical instrument  10  may be provided with a corresponding encoder that communicates with a microprocessor chip on the proximal circuit board  820 . For example, the articulation control motor  402  may have an encoder  404  operably coupled thereto that communicates with the proximal circuit board  820 . The firing or transection motor  530  may have an encoder  534  operably coupled thereto that communicates with the proximal circuit board  820 . The end effector rotation or distal roll motor  560  may have an encoder  564  operably coupled thereto that communicates with the proximal circuit board  820 . The shaft rotation or proximal roll motor  610  may have an encoder  614  operably coupled thereto that communicates with the proximal circuit board  820 . The encoders may serve to provide the corresponding microprocessor chips with feedback regarding the number of rotations and direction of rotation for each of the motors. In some forms, in addition to the encoders, the rotation drive assembly  570  may employ sensor arrangements to track the rotation of the various shaft segments. For example, as can be seen in  FIGS. 15, 28, and 29 , the articulation drive pulley  417  may have a first articulation sensor  419  mounted thereto that is adapted to be detected by a second articulation sensor  421  which may comprise, for example, a hall effect sensor, that is mounted to the distal circuit board  810 . The first and second articulation sensors  419 ,  421  serve to provide an additional means of feedback for tracking the rotatable position of the proximal articulation shaft  420 . Likewise, the distal roll pulley  575  of the rotation drive assembly  570  may have a first distal roll sensor  580  mounted thereto that is adapted to be detected by a second distal roll sensor  582  that is mounted to the distal circuit board  810 . See  FIGS. 24, 28, and 29 . The first and second distal roll sensors  580 ,  582  serve to provide an additional means of feedback for tracking the rotatable position of the proximal rotation shaft segment  552 . In addition, the pulley  632  of the proximal roll drive assembly  620  may have a first proximal roll sensor  634  that is adapted to be detected by a second proximal roll sensor  636  mounted to the distal circuit board  810 . See  FIGS. 26, 28, and 29 . The first and second proximal roll sensors  634 ,  636  serve to provide an additional means of feedback for tracking the rotatable position of the proximal outer shaft segment  602 . 
     Conductive Pathways from End Effector to Handle Assembly 
     As discussed herein, various forms of the surgical instrument  10  may be effectively employed with a variety of different end effectors or surgical implements that require or employ rotary or other motions for end effector/implement operation/manipulation. For example, one form of the end effector  102  requires rotary control motions to open and close the anvil assembly  190 , drive the surgical staples and transect tissue. One form of the end effector  102  may also be equipped with a distal sensor arrangement for sensing a degree or amount of closure attained by the anvil assembly  190  relative to the surgical staple cartridge  130 . For example, the anvil assembly  190  may include a first anvil sensor  890  that is mounted in the distal end thereof. See  FIG. 3 . The anvil sensor  890  may comprise, for example, a hall effector sensor that is configured to detect a second staple cartridge sensor (magnet)  892  mounted in the distal end of the surgical staple cartridge  130 . In at least one form, the first anvil sensor  890  may communicate with at least one an end effector conductor  894  that is mounted on the anvil assembly  190  as shown. In one form for example, the end effector conductor  894  comprises a flat metal strip that has a flexible hook  896  formed on the proximal end thereof. As generally used herein, the terms “conductor” or “conductive” refer to a member or component that is capable of conducting electricity therethrough. A conductor, for example, may comprise wire or wires, flexible conductive strips or metal traces, multi-channel conductive ribbon cable, etc. As used herein, the terms “electrically contacts” and “electrically communicates with” means that the components are configured to pass electrical current or signals therebetween. 
     Referring now to  FIGS. 45 and 46 , it can be seen that the flexible hook  896  may be oriented for contact with the distal end  244  of the locking pin  242 . The locking pin  242  may, for example, be constructed from electrical conductive material and be coated with an insulative coating (e.g., polymer, etc.) to electrically insulate the locking pin  242  from the coupler housing segment  202  but have an exposed tip configured to make electrical contact with the hook  896 . In addition, the locking spring  246  may also be fabricated from an electrical conductive material (e.g., metal). The locking spring  246  may be attached (e.g., soldered, etc.) to the locking pin  242  such that the locking pin  242  and locking spring  246  form an electrically conductive coupler pathway for conducting electrical current through the coupler assembly  200 . The locking spring  246  may also be coated with an insulative coating to electrically insulate it from the coupler housing segment  202 . The locking pin  242  and the locking spring  246  may be collectively referred to herein as a “locking pin assembly”  249 . The locking spring  246  may terminate in a proximal end  247  that is configured for slidable electrical contact with a proximal conductor assembly  250  that is mounted to the distal clevis  312  of the articulation joint  310 . 
     As can be seen in  FIG. 8 , one form of proximal conductor assembly  250  may include conductor wire/wires/trace  252  and an annular electrical conductor in the form of, for example, a conductive washer  254 . As can be seen in  FIG. 46 , the conductor  252  communicates with a proximal conductor portion  256  that protrudes out through the distal clevis  312  to communicate with an articulation joint conductor  258  supported by a flexible joint cover  900  that extends over the articulation joint  310 . In at least one form, the joint cover  900  includes a hollow body  902  that has an open proximal end  904  and an open distal end  906  and a joint receiving passage  908  extending therebetween. The hollow body  902  may contain a plurality of ribs  910  and be fabricated from a polymer or similar non-electrically-conductive material that is omni-directionally stretchable to accommodate movement of the articulation joint components. However, the joint cover  900  could also be fabricated from other suitable materials and arrangements such as flexible micro-cut tubing, etc. The articulation joint conductor  258  may comprise for example, a conductive ribbon cable, wire, wires, trace, etc. As can be further seen in  FIG. 46 , a proximal end of the articulation joint conductor  258  is electrically coupled to a shaft conductor  260  on the proximal outer shaft segment  602 . 
     Referring now to  FIGS. 47 and 48 , in at least one form, the proximal end of the shaft conductor  260  may be oriented for sliding contact with an annular conductor ring  262  that is mounted in the handle assembly  20 . Such arrangement may enable electrical current to flow between the shaft conductor  260  and the conductor ring  262  as the elongate shaft assembly  30  is rotated about the shaft axis A-A relative to the handle assembly  20 . As can be further seen in  FIGS. 47 and 48 , a conductor  264  is coupled to the conductor ring  262  and extends proximally through the handle housing  20 . The conductor  264  may comprise a wire or other suitable electrical conductor and have a proximal end  266  that is configured to flexibly contact the tip of the left locator pin  774 . In particular, for example, the proximal end  266  may extend through the wall of the left locator socket  718  such that when the left locator pin  774  is inserted therein, the proximal end portion  266  of the conductor  264  makes contact with the left locator pin  774 . In at least one form, the left locator pin  774  is fabricated from electrically conductive material (metal) such that when the proximal end  266  of the conductor  264  makes contact therewith, electrical current can flow between those components. In addition, an attachment conductor  776  serves to electrically couple the left locator pin  774  to the proximal circuit board assembly  820  to facilitate transfer of electrical current therebetween. 
     The above-described arrangement facilitates the passage of electrical current between the end effector or surgical implement that has been attached to the elongate shaft assembly  30  of the surgical instrument  10  and the control system components located in the handle assembly  20  of the surgical instrument  10 . This conductive pathway is maintained while also maintaining the ability to rotate the end effector relative to the elongate shaft assembly, articulate the end effector relative to the elongate shaft assembly and rotate the end effector and elongate shaft assembly as a unit. The joint cover  900  may provide an electrical communication path between the elongate shaft and the end effector. The joint cover  900  may contain an electrical flex strip, wire, trace, etc. to conduct more than one signal for electrical communication. Thus, a plurality of different sensors or electrical components may be employed in the end effector to provide various forms of feedback to the user. For example, sensors may be employed determine the number of use cycles, track the progress of the cutting instrument within the end effector during firing, provide feedback to the control system to automatically control the various motors in the handle assembly, etc. 
       FIG. 49  illustrates an alternative articulation joint  310 ′ that is configured to permit the passage of electrical current or signals therethrough. In this form, a distal electrical joint conductor  270  is provided through the distal clevis  312 ′ to contact a distal metal washer  272  embedded therein as shown. The proximal clevis  330 ′ may have a proximal metal washer  274  mounted thereto for rotational contact with the distal metal washer  272  when the distal clevis  312 ′ is coupled to the proximal clevis  330 ″ in the manner described above. The proximal metal washer  274  may be curved or beveled to maintain sliding contact between the washers  272 ,  274 . A proximal electrical joint conductor  276  in the form of, for example, a contactor strip, wire or trace is attached to the washer  274  and is configured for electrical contact with the shaft conductor  260  on the proximal outer shaft segment  602 . Thus, such arrangement facilitates the passage of electrical current/signals from the end effector  102  through the locking pin  242 , locking spring  242  (i.e., the locking pin assembly  249 ), conductor ring  252 , distal electrical joint conductor  270 , washers  272 ,  274  and the proximal electrical joint conductor  276  to the shaft conductor  260 . 
     Alternative Articulation Joint Arrangements 
     Another form of articulation joint  1000  is shown in  FIGS. 50-53 . Such articulation joint  1000  can facilitate the articulation and rotation of an end effector or surgical implement coupled thereto relative to the shaft axis A-A of the elongate shaft to which the articulation joint  1000  is attached. The articulation joint may also facilitate such movement of the end effector or surgical implement while also providing a rotary control motion to the end effector/implement for actuation or manipulation thereof. The articulation joint  1000  may be coupled to an elongate shaft assembly that is similar in construction to the elongate shaft assembly  30  described above or it may be coupled to other suitable shaft assemblies. The elongate shaft assembly may be coupled to a handle assembly that houses a plurality of motors. One motor may be used to apply control motions to a flexible cable member  1010  that extends through the elongate shaft assembly and which is operably coupled to the articulation joint  1000 . For example, the flexible cable  1010  may be attached to a sheave or pulley assembly that is operably attached to or communicates with the shaft of a corresponding motor such that operation of the motor causes the cable  1010  to be actuated. The handle assembly may also include a firing motor that is operably attached to a proximal firing shaft  1030  that extends through the elongate shaft assembly to interface with the articulation joint  1000  as will be discussed in further detail below. The handle assembly may also include a motor that operably interfaces with an end effector or distal roll shaft  1040  that transmits a rotary control motion to the articulation joint  1000  which may be used to rotate the end effector or surgical implement about the shaft axis A-A relative to the elongate shaft. The handle assembly may also include a proximal roll motor that is employed to rotate the elongate shaft assembly about the shaft axis A-A in the manner described above. 
     In at least one form, the articulation joint  1000  may include a proximal clevis assembly  1020  that is attached to or formed on the end of the elongate shaft assembly. In the arrangement shown in  FIGS. 50-53 , the proximal clevis assembly  1020  is formed on a distal end of the elongate shaft assembly  30 ′. As can be seen in those Figures, the proximal clevis assembly  1020  has a distal end wall  1022  and a pair of spaced clevis arms  1024 ,  1026 . The proximal clevis  1020  is configured to be pivotally coupled to a distal clevis  1050  by a pivot shaft  1051  which serves to define articulation axis B-B. Articulation axis B-B may be substantially transverse to shaft axis A-A. 
     The distal clevis  1050  has a socket  1052  formed thereon and a pair of distal clevis arms  1054 ,  1056 . The pivot shaft  1051  extends centrally through the clevis arms  1024 ,  1054 ,  1056 , and  1026  as shown in  FIG. 53 . The clevis arm  1054  may have a cable pulley  1058  formed thereon to which the flexible cable  1010  is attached. Thus, rotation of the cable  1010  by its corresponding motor will result in rotation of the distal clevis  1050  relative to the proximal clevis  1020  about the articulation axis B-B. 
     In various forms, the articulation joint  1000  may further include a rotatable mounting hub  1060  that is rotatably received within the socket  1052 . The mounting hub  1060  may have a ring gear  1062  attached thereto that is adapted for meshing engagement with a distal roll pinion gear  1064 . The distal roll pinion gear  1064  is attached to a pinion shaft  1066  that is rotatably supported in an end wall  1053  of the distal clevis  1050 . The pinion shaft  1066  has a distal roll output gear  1068  attached thereto. The distal roll output gear  1068  is supported in meshing engagement with distal roll transfer gear  1070  that is rotatably journaled on the pivot shaft  1051  and is in meshing engagement with a distal roll input gear  1072 . The distal roll input gear  1072  is mounted to the distal roll shaft  1040 . The distal roll output gear  1068 , the distal roll transfer gear  1070  and the distal roll input gear  1072  are referred to herein as the “distal roll gear train”, generally designated as  1069 . The distal roll transfer gear  1070  is “free-wheeling” on the pivot shaft  1051  such that rotation of the distal roll shaft  1040  ultimately results in the rotation of the of the distal roll pinion gear  1064  without rotating the pivot shaft  1051 . Rotation of the distal roll pinion gear  1064  within the ring gear  1062  results in the rotation of the mounting hub  1060  about the shaft axis A-A. In various forms, an end effector or surgical implement may be directly coupled to the mounting hub  1060  such that rotation of the mounting hub  1060  results in rotation of the end effector/implement. For example, the mounting hub  1060  may be formed with a hub socket  1061  that is sized to retainingly receive a portion of the end effector/implement therein. In alternative arrangements, the mounting hub  1060  may comprise an integral part of the end effector or the end effector may be attached to the mounting hub  1060  by other fastener arrangements. For example, the mounting hub  1060  may be attached to a coupling assembly of the type and construction described above and then the end effector/implement may be detachably attached to the coupling assembly. 
     The articulation joint  1000  may also facilitate transfer of a rotary control motion through the joint  1000  to the end effector/implement attached thereto. As can be seen in  FIGS. 52 and 53 , a distal end of the proximal firing shaft  1030  is rotatably supported by the distal end wall  1022  of the proximal clevis assembly  1020  and has an input firing gear  1080  attached thereto. The input firing gear  1080  is in meshing engagement with a firing transfer gear  1082  that is journaled on the pivot shaft  1051 . The firing transfer gear  1082  is in meshing engagement with a firing output gear  1084  that is mounted on a firing output shaft  1090  that is mounted in the end wall  1053  of the distal clevis  1050 . The firing output shaft  1090  may be configured for driving engagement with a corresponding drive member or shaft on the end effector/implement. For example, the distal end  1092  of the firing output shaft  1090  may be formed with a hexagonal shape so that it may be received in a corresponding hexagonal socket formed in a mounting flange  1094  that may be configured to be attached to the drive shaft of the end effector/implement. The firing input gear  1080 , the firing transfer gear  1082 , and the firing output gear  1084  are referred to herein as the “firing shaft gear train”, generally designated as  1081 . The firing transfer gear  1082  is “free-wheeling” on the pivot shaft  1051  such that rotation of the proximal firing shaft  1030  ultimately results in the rotation of the of the firing output shaft  1090  without rotating the pivot shaft  1051 . The distal roll gear train  1069  and the firing shaft gear train  1081  are essentially “nested” together facilitate articulation of the end effector/implement relative to the elongate shaft assembly while facilitating the transfer of rotary control motions to the end effector and while facilitating the rotation of the end effector about the shaft axis A-A. 
       FIGS. 54-60  illustrate another alternative articulation joint arrangement  1100 . In at least one form, the articulation joint  1100  may include a proximal clevis  1110 , a central clevis  1130  and a distal clevis  1150 . The articulation joint  1100  may be configured to facilitate the articulation of an end effector or surgical implement coupled thereto about two different articulation axes B-B and C-C that are substantially transverse to each other as well as to the shaft axis A-A of an elongate shaft assembly  30 ″ to which it is attached. For example, the articulation joint  1100  may be configured such that the central clevis  1130  may be pivoted about the first articulation axis B-B relative to the first clevis  1110  and the distal clevis  1150  may be selectively pivoted about a second articulation axis C-C relative to the central clevis  1130 . The articulation joint  1100  may also facilitate such articulation of the end effector or surgical implement while also providing a rotary control motion to the end effector/implement for actuation or manipulation thereof. 
     The articulation joint  1100  may be coupled to an elongate shaft assembly that is similar in construction to the elongate shaft assembly  30  described above or it may be coupled to other suitable shaft assemblies. In one arrangement, the proximal clevis  1110  is integrally formed with the outer tube of the elongate shaft assembly  30 ″. As can be seen in  FIGS. 54-60 , the proximal clevis  1110  has an upper proximal clevis arm  1112  and a lower proximal clevis arm  1114 . The central clevis  1130  also has an upper central clevis arm  1132  and a lower central clevis arm  1134 . The upper proximal clevis arm is pivotally coupled to the upper central clevis arm  1132  by a proximal pivot pin  1116 . The proximal pivot pin  1116  also pivotally couples the lower proximal clevis arm  1114  to the lower central clevis arm  1134 . The proximal pivot pin  1116  serves to define the first articulation axis B-B. 
     Also in at least one arrangement, the central clevis  1130  has a right central clevis arm  1136  and a left central clevis arm  1138 . The distal clevis  1150  has a right distal clevis arm  1152  and a left distal clevis arm  1154 . The right central clevis arm  1136  is pivotally coupled to the right distal clevis arm  1152  by a distal pivot pin  1156 . The left central clevis arm  1138  is pivotally coupled to the left distal clevis arm  1154  by the distal pivot pin  1156 . The distal pivot pin  1156  defines the second articulation axis C-C. In one arrangement, the distal pivot pin  1156  is non-pivotally attached to the right and left distal clevis arms  1152 ,  1154  such that the distal pivot pin  1156  rotates with the distal clevis  1150  relative to the central clevis  1130 . 
     The elongate shaft assembly  30 ″ may be coupled to a handle assembly that houses a plurality of motors. One motor may be used to apply control motions to a first flexible cable member  1170  that extends through the elongate shaft assembly  30 ″ and which is operably coupled to the articulation joint  1100 . For example, the first flexible cable  1170  may be attached to a first sheave or pulley assembly that is operably attached to or communicates with the shaft of a corresponding motor such that operation of the motor causes the first cable  1170  to be actuated. 
     In one arrangement, the first flexible cable  1170  may be employed to selectively pivot the central clevis  1130  relative to the proximal clevis  1110  about the first articulation axis B-B. In such arrangement, for example, the first cable  1170  extends around a first pulley or sheave  1180  that is attached to the central clevis  1130 . For example, the first pulley  1180  is attached to the upper central clevis arm  1132  and pivotally journaled on the proximal pivot pin  1116 . Actuation of the first cable  1170  will cause the central clevis  1130  to pivot relative to the proximal clevis  1110  about the first articulation axis B-B. 
     The articulation joint  1100  may also employ a second flexible cable  1190  that is received on a sheave or pulley assembly that is operably attached to or communicates with the shaft of a corresponding motor within the handle assembly such that operation of the motor causes the second cable  1190  to be actuated. The second cable  1190  may be employed to selectively pivot the distal clevis  1150  relative to the central clevis  1130  about the second articulation axis C-C. In such arrangement, for example, the second cable  1190  extends around a second pulley or sheave  1158  that is non-rotatably attached to the distal pivot pin  1156 . Actuation of the second cable  1190  will result in the rotation of the distal pivot pin  1156  and the distal clevis  1150  attached thereto about the second articulation axis C-C relative to the central clevis  1130 . 
     The articulation joint  1100  may also facilitate transfer of a rotary control motion through the joint  1100  to the end effector/implement attached thereto. A proximal rotary firing shaft  1200  may extend through the elongate shaft assembly  30 ″ and be operably coupled to a firing motor in the handle assembly for applying a rotary firing motion thereto. In one arrangement, the proximal firing shaft  1200  may be hollow such that the second cable  1190  may extend therethrough. The proximal firing shaft  1200  may operably interface with a proximal firing gear train  1210  operably supported in the articulation joint  1100 . For example, in one arrangement, the first firing gear train  1210  may include a proximal input firing gear  1212  that is attached to the proximal firing shaft  1200 . The proximal input firing gear  1212  is oriented in meshing engagement with a proximal firing transfer gear  1214  that is journaled on the proximal pivot shaft  1116  such that it can freely rotate thereon. The proximal firing transfer gear  1212  is oriented in meshing engagement with a proximal firing output gear  1216  that is coupled to a central firing shaft  1218  that rotatably passes through a central web  1131  of the central clevis  1130 . 
     The articulation joint  1100  may further include a distal firing gear train  1220  that cooperates with the proximal firing gear train  1210  to transfer the rotary firing or control motion through the articulation joint  1100 . The distal firing gear train  1220  may include a distal firing input gear  1222  that is mounted to the central firing shaft  1216 . The distal firing input gear  1222  is in meshing engagement with a distal firing transfer gear  1224  that is rotatably mounted to the distal pivot pin  1156  such that it may freely rotate thereon. The distal firing transfer gear  1224  is in meshing engagement with a distal firing output gear  1226  that is rotatably supported within the distal clevis  1150 . The distal firing output gear  1226  may be configured for driving engagement with a corresponding drive member or shaft on the end effector/implement. 
     Another form of articulation joint  1300  is shown in  FIGS. 61-66 . Such articulation joint  1300  can facilitate the articulation and rotation of an end effector or surgical implement coupled thereto relative to the shaft axis A-A of the elongate shaft to which the articulation joint  1300  is attached. The articulation joint may also facilitate such movement of the end effector or surgical implement while also providing a rotary control motion to the end effector/implement for actuation or manipulation thereof. The articulation joint  1300  may be coupled to an elongate shaft assembly that is similar in construction to the elongate shaft assembly  30  described above or it may be coupled to other suitable shaft assemblies. The elongate shaft assembly may be coupled to a handle assembly that houses a plurality of motors. One motor may be used to apply control motions to a flexible cable  1310  that extends through the elongate shaft assembly and which is operably coupled to the articulation joint  1300 . For example, the flexible cable  1310  may be attached to a sheave or pulley assembly that is operably attached to or communicates with the shaft of a corresponding motor such that operation of the motor causes the cable  1310  to be actuated. The handle assembly may also include a firing motor that is operably attached to a proximal firing shaft  1330  that extends through the elongate shaft assembly to interface with the articulation joint  1300  as will be discussed in further detail below. The handle assembly may also include a motor that operably interfaces with a flexible distal roll shaft  1340  that transmits a rotary control motion to the articulation joint  1300  which may be used to rotate the end effector or surgical implement about the shaft axis A-A relative to the elongate shaft. The handle assembly may also include a proximal roll motor that is employed to rotate the elongate shaft assembly about the shaft axis A-A in the manner described above. 
     In at least one form, the articulation joint  1300  may include a proximal clevis assembly  1320  that is attached to or formed on the end of the elongate shaft assembly. In the arrangement shown in  FIGS. 61-66 , the proximal clevis assembly  1320  is formed on a distal end of an outer tube forming a portion of the elongate shaft assembly  30 ″. As can be seen in those Figures, the proximal clevis assembly  1320  has a distal end wall  1322  and a pair of spaced clevis arms  1324 ,  1326 . The proximal clevis  1320  is configured to be pivotally coupled to a distal clevis  1350  by an upper pivot shaft  1351  and a lower pivot shaft  1353  which serve to define articulation axis B-B. Articulation axis B-B is substantially transverse to shaft axis A-A. 
     The distal clevis  1350  has a socket  1352  formed thereon and a pair of distal clevis arms  1354 ,  1356 . The upper pivot shaft  1351  extends centrally through the clevis arms  1324  and  1354 . The lower pivot shaft  1353  extends through the clevis arms  1356 , and  1026  as shown in  FIG. 64 . The clevis arm  1356  further has a cable pulley  1358  formed thereon or attached thereto. The flexible cable  1310  is attached to the cable pulley  1358  such that actuation of the cable  1310  will result in articulation of the distal clevis  1350  about the articulation axis B-B relative to the proximal clevis  1320 . 
     In various forms, the articulation joint  1300  may further include a rotatable mounting hub  1360  that is rotatably received within the socket  1052 . The mounting hub  1060  may have a driven gear  1362  attached thereto that is adapted for meshing engagement with a distal roll pinion gear  1364 . The distal roll pinion gear  1364  is attached to a pinion shaft  1366  that is rotatably supported in an end wall  1355  of the distal clevis  1350 . In at least one arrangement, the distal roll pinion gear  1364  is operated by the flexible distal roll shaft  1340  that extends through a proximal support shaft  1342  extending through the elongate shaft assembly  30 ″. In various forms, an end effector or surgical implement may be directly coupled to the mounting hub  1360  such that rotation of the mounting hub  1360  results in rotation of the end effector/implement. For example, the mounting hub  1360  may be formed with a hub socket  1361  that is sized to retainingly receive a portion of the end effector/implement therein. In alternative arrangements, the mounting hub  1360  may comprise an integral part of the end effector or the end effector may be attached to the mounting hub  1360  by other fastener arrangements. For example, the mounting hub  1360  may be attached to a coupling assembly of the type and construction described above and then the end effector/implement may be detachably attached to the coupling assembly. 
     The articulation joint  1300  may also facilitate transfer of a rotary control motion through the joint  1300  to the end effector/implement attached thereto. As can be seen in  FIGS. 63 and 64 , a distal end of the proximal firing shaft  1330  is rotatably supported by the distal end wall  1322  of the proximal clevis assembly  1320  and has a firing input gear  1380  attached thereto. The input firing gear  1380  is in meshing engagement with a firing transfer gear  1382  that is journaled on the lower pivot shaft  1353 . The firing transfer gear  1382  is in meshing engagement with a firing output gear  1384  that is mounted on a firing output shaft  1390  that extends through the end wall  1355  of the distal clevis  1350  and the end wall  1370  of the mounting hub  1360 . The firing output shaft  1390  may be configured for driving engagement with a corresponding drive member or shaft on the end effector/implement. For example, the distal end  1392  of the firing output shaft  1390  may be formed with a hexagonal shape so that it may be received in a corresponding hexagonal socket formed in a mounting flange  1394  that may be configured to be attached to the drive shaft of the end effector/implement. The firing input gear  1380 , the firing transfer gear  1382 , and the firing output gear  1384  are referred to herein as the firing shaft gear train, generally designated as  1381 . The firing transfer gear  1382  is “free-wheeling” on the lower pivot shaft  1353  such that rotation of the proximal firing shaft  1330  ultimately results in the rotation of the of the firing output shaft  1390  without rotating the lower pivot shaft  1353 . The distal roll gear train  1369  and the firing shaft gear train  1381  facilitate articulation of the end effector/implement relative to the elongate shaft assembly while facilitating the transfer of rotary control motions to the end effector and while facilitating the rotation of the end effector about the shaft axis A-A. 
     Alternative Motor Mounting Assemblies 
       FIGS. 67-69  illustrate an alternative motor mounting assembly generally designated as  1750 . The motor mounting assembly  1750  may be supported within handle housing segments  23  and  24  that are couplable together by snap features, screws, etc. and serve to form a pistol grip portion  26  of the handle assembly  20 . In at least one form, the motor mounting assembly  1750  may comprise a motor housing  1752  that is removably supported within the handle housing segments  23  and  24 . In at least one form, for example, the motor housing  1752  has a motor bulkhead assembly  1756  attached thereto. The motor housing  1752  serves to support motors  402 ,  530 ,  560  and  610 . Each motor has its own circuit control board  1780  attached thereto for controlling the operation of each motor in the various manner described herein. 
     In some forms, the implement portion  100  may comprise an electrosurgical end effector that utilizes electrical energy to treat tissue. Example electrosurgical end effectors and associated instruments are described in U.S. patent application Ser. No. 13/536,393, entitled SURGICAL END EFFECTOR JAW AND ELECTRODE CONFIGURATIONS, now U.S. Patent Application Publication No. 2014/0005640, and U.S. patent application Ser. No. 13/536,417, entitled ELECTRODE CONNECTIONS FOR ROTARY DRIVE SURGICAL TOOLS, now U.S. Pat. No. 9,101,385, both of which are incorporated by reference herein in their entireties.  FIGS. 70-73  illustrate an example end effector  3156  making up an alternate implement portion  100 . The end effector  3156  may be adapted for capturing and transecting tissue and for the contemporaneously welding the captured tissue with controlled application of energy (e.g., radio frequency (RF) energy). The first jaw  3160 A and the second jaw  3160 B may close to thereby capture or engage tissue about a longitudinal axis  3194  defined by an axially moveable member  3182 . The first jaw  3160 A and second jaw  3160 B may also apply compression to the tissue. 
       FIG. 70  shows a perspective view of some forms of an electrosurgical end effector  3156  for use with the surgical instrument  10 .  FIG. 70  shows the end effector  3156  with the jaws  3160 A,  3160 B open.  FIG. 71  shows a perspective view of some forms of the end effector  3156  with the jaws  3160 A,  3160 B closed. As noted above, the end effector  3156  may comprise the upper first jaw  3160 A and the lower second jaw  3160 B, which may be straight or curved. The first jaw  3160 A and the second jaw  3160 B may each comprise an elongate slot or channel  3162 A and  3162 B ( FIG. 70 ), respectively, disposed outwardly along their respective middle portions. Further, the first jaw  3160 A and second jaw  3160 B may each have tissue-gripping elements, such as teeth  3198 , disposed on the inner portions of first jaw  3160 A and second jaw  3160 B. The first jaw  3160 A may comprise an upper first jaw body  3200 A with an upper first outward-facing surface  3202 A and an upper first energy delivery surface  3204 A. The second jaw  3160 B may comprise a lower second jaw body  3200 B with a lower second outward-facing surface  3202 B and a lower second energy delivery surface  3204 B. The first energy delivery surface  3204 A and the second energy delivery surface  3204 B may both extend in a “U” shape about the distal end of the end effector  3156 . It will be appreciated that the end effector  3156  may be rotatable and articulatable in a manner similar to that described herein with respect to the end effector  102 . 
       FIG. 72  shows one form of an axially movable member  3182  of the end effector  3156 . The axially movable member  3182  is driven by a threaded drive shaft  3151 . ( FIG. 70 ) A proximal end of the threaded drive shaft  3151  may be configured to be non-rotatably coupled to the output socket  238  and thereby receive rotational motion provided by the motor  530 . The axially movable member  3182  may comprise a threaded nut  3153  for receiving the threaded drive shaft  3151  such that rotation of the threaded drive shaft  3151  causes the axially movable member  3182  to translate distally and proximally along the axis  3194 . ( FIG. 72 ) The axially moveable member  3182  may comprise one or several pieces, but in any event, may be movable or translatable with respect to the elongate shaft  158  and/or the jaws  3160 A,  3160 B. Also, in at least some forms, the axially moveable member  3182  may be made of 17-4 precipitation hardened stainless steel. The distal end of axially moveable member  3182  may comprise a flanged “I”-beam configured to slide within the channels  3162 A and  3162 B in jaws  3160 A and  3160 B. The axially moveable member  3182  may slide within the channels  3162 A,  3162 B to open and close first jaw  3160 A and second jaw  3160 B. The distal end of the axially moveable member  3182  may also comprise an upper flange or “c”-shaped portion  3182 A and a lower flange or “c”-shaped portion  3182 B. The flanges  3182 A and  3182 B respectively define inner cam surfaces  3206 A and  3206 B for engaging outward facing surfaces of first jaw  3160 A and second jaw  3160 B. The opening-closing of jaws  3160 A and  3160 B can apply very high compressive forces on tissue using cam mechanisms which may include movable “I-beam” axially moveable member  3182  and the outward facing surfaces  3208 A,  3208 B of jaws  3160 A,  3160 B. 
     More specifically, referring now to  FIGS. 70-72 , collectively, the inner cam surfaces  3206 A and  3206 B of the distal end of axially moveable member  3182  may be adapted to slidably engage the first outward-facing surface  3208 A and the second outward-facing surface  3208 B of the first jaw  3160 A and the second jaw  3160 B, respectively. The channel  3162 A within first jaw  3160 A and the channel  3162 B within the second jaw  3160 B may be sized and configured to accommodate the movement of the axially moveable member  3182 , which may comprise a tissue-cutting element  3210 , for example, comprising a sharp distal edge.  FIG. 71 , for example, shows the distal end of the axially moveable member  3182  advanced at least partially through channels  3162 A and  3162 B ( FIG. 70 ). The advancement of the axially moveable member  3182  may close the end effector  3156  from the open configuration shown in  FIG. 70 . In the closed position shown by  FIG. 71 , the upper first jaw  3160 A and lower second jaw  3160 B define a gap or dimension D between the first energy delivery surface  3204 A and second energy delivery surface  3204 B of first jaw  3160 A and second jaw  3160 B, respectively. In various forms, dimension D can equal from about 0.0005″ to about 0.040″, for example, and in some forms, between about 0.001″ to about 0.010″, for example. Also, the edges of the first energy delivery surface  3204 A and the second energy delivery surface  3204 B may be rounded to prevent the dissection of tissue. 
       FIG. 73  is a section view of some forms of the end effector  3156 . The engagement, or tissue-contacting, surface  3204 B of the lower jaw  3160 B is adapted to deliver energy to tissue, at least in part, through a conductive-resistive matrix, such as a variable resistive positive temperature coefficient (PTC) body. At least one of the upper and lower jaws  3160 A,  3160 B may carry at least one electrode  3212  configured to deliver the energy from a generator  3164  to the captured tissue. The engagement, or tissue-contacting, surface  3204 A of upper jaw  3160 A may carry a similar conductive-resistive matrix (e.g., a PTC material), or in some forms the surface may be a conductive electrode or an insulative layer, for example. Alternatively, the engagement surfaces of the jaws can carry any of the energy delivery components disclosed in U.S. Pat. No. 6,773,409, filed Oct. 22, 2001, entitled ELECTROSURGICAL JAW STRUCTURE FOR CONTROLLED ENERGY DELIVERY, the entire disclosure of which is incorporated herein by reference. 
     The first energy delivery surface  3204 A and the second energy delivery surface  3204 B may each be in electrical communication with the generator  3164 . The generator  3164  is connected to the end effector  3156  via a suitable transmission medium such as conductors  3172 ,  3174 . In some forms, the generator  3164  is coupled to a controller, such as a control unit  3168 , for example. In various forms, the control unit  3168  may be formed integrally with the generator  3164  or may be provided as a separate circuit module or device electrically coupled to the generator  3164  (shown in phantom to illustrate this option). The generator  3164  may be implemented as an external piece of equipment and/or may be implemented integral to the surgical instrument  10 . 
     The first energy delivery surface  3204 A and the second energy delivery surface  3204 B may be configured to contact tissue and deliver electrosurgical energy to captured tissue which are adapted to seal or weld the tissue. The control unit  3168  regulates the electrical energy delivered by electrical generator  3164  which in turn delivers electrosurgical energy to the first energy delivery surface  3204 A and the second energy delivery surface  3204 B. The control unit  3168  may regulate the power generated by the generator  3164  during activation. 
     As mentioned above, the electrosurgical energy delivered by electrical generator  3164  and regulated, or otherwise controlled, by the control unit  3168  may comprise radio frequency (RF) energy, or other suitable forms of electrical energy. Further, the opposing first and second energy delivery surfaces  3204 A and  3204 B may carry variable resistive positive temperature coefficient (PTC) bodies that are in electrical communication with the generator  3164  and the control unit  3168 . Additional details regarding electrosurgical end effectors, jaw closing mechanisms, and electrosurgical energy-delivery surfaces are described in the following U.S. patents and published patent applications: U.S. Pat. Nos. 7,087,054; 7,083,619; 7,070,597; 7,041,102; 7,011,657; 6,929,644; 6,926,716; 6,913,579; 6,905,497; 6,802,843; 6,770,072; 6,656,177; 6,533,784; and 6,500,176; and U.S. Patent Application Publication Nos. 2010/0036370 and 2009/0076506, all of which are incorporated herein in their entirety by reference and made a part of this specification. 
     A suitable generator  3164  is available as model number GEN11, from Ethicon Endo-Surgery, Inc., Cincinnati, Ohio. Also, in some forms, the generator  3164  may be implemented as an electrosurgery unit (ESU) capable of supplying power sufficient to perform bipolar electrosurgery using radio frequency (RF) energy. In some forms, the ESU can be a bipolar ERBE ICC 350 sold by ERBE USA, Inc. of Marietta, Ga. In some forms, such as for bipolar electrosurgery applications, a surgical instrument having an active electrode and a return electrode can be utilized, wherein the active electrode and the return electrode can be positioned against, adjacent to and/or in electrical communication with, the tissue to be treated such that current can flow from the active electrode, through the positive temperature coefficient (PTC) bodies and to the return electrode through the tissue. Thus, in various forms, the surgical instrument  10  utilizing the end effector  3156  creates a supply path and a return path, wherein the captured tissue being treated completes, or closes, the circuit. In some forms, the generator  3164  may be a monopolar RF ESU and the surgical instrument  10  may utilize comprise a monopolar end effector in which one or more active electrodes are integrated. For such a system, the generator  3164  may utilize a return pad in intimate contact with the patient at a location remote from the operative site and/or other suitable return path. The return pad may be connected via a cable to the generator  3164 . 
     During operation of electrosurgical instrument  150 , the user generally grasps tissue, supplies energy to the captured tissue to form a weld or a seal, and then drives a tissue-cutting element  3210  at the distal end of the axially moveable member  3182  through the captured tissue. According to various forms, the translation of the axial movement of the axially moveable member  3182  may be paced, or otherwise controlled, to aid in driving the axially moveable member  3182  at a suitable rate of travel. By controlling the rate of the travel, the likelihood that the captured tissue has been properly and functionally sealed prior to transection with the cutting element  3210  is increased. 
     In some forms, the implement portion  100  may comprise an ultrasonic end effector that utilizes harmonic or ultrasonic energy to treat tissue.  FIG. 74  illustrates one form of an ultrasonic end effector  3026  for use with the surgical instrument  10 . The end effector assembly  3026  comprises a clamp arm assembly  3064  and a blade  3066  to form the jaws of the clamping mechanism. The blade  3066  may be an ultrasonically actuatable blade acoustically coupled to an ultrasonic transducer  3016  positioned within the end effector  3026 . Examples of small sized transducers and end effectors comprising transducers are provided in U.S. patent application Ser. No. 13/538,601, ENTITLED ULTRASONIC SURGICAL INSTRUMENTS WITH DISTALLY POSITIONED TRANSDUCERS, now U.S. Patent Application Publication No. 2014/0005702, and U.S. Patent Application Publication No. 2009/0036912, now U.S. Pat. No. 8,430,898. The transducer  3016  may be acoustically coupled (e.g., directly or indirectly mechanically coupled) to the blade  3066  via a waveguide  3078 . 
     A tubular actuating member  3058  may move the clamp arm assembly  3064  to an open position in direction  3062 A wherein the clamp arm assembly  3064  and the blade  3066  are disposed in spaced relation relative to one another and to a clamped or closed position in direction  3062 B wherein the clamp arm assembly  3064  and the blade  3066  cooperate to grasp tissue therebetween. The distal end of the tubular reciprocating tubular actuating member  3058  is mechanically engaged to the end effector assembly  3026 . In the illustrated form, the distal end of the tubular reciprocating tubular actuating member  3058  is mechanically engaged to the clamp arm assembly  3064 , which is pivotable about the pivot point  3070 , to open and close the clamp arm assembly  3064 . For example, in the illustrated form, the clamp arm assembly  3064  is movable from an open position to a closed position in direction  3062 B about a pivot point  3070  when the reciprocating tubular actuating member  3058  is retracted proximally. The clamp arm assembly  3064  is movable from a closed position to an open position in direction  3062 A about the pivot point  3070  when the reciprocating tubular actuating member  3058  is translated distally. ( FIG. 75 ) 
     The tubular actuating member  3058  may be translated proximally and distally due to rotation of a threaded drive shaft  3001 . A proximal end of the threaded drive shaft  3001  may be configured to be non-rotatably coupled to the output socket  238  and thereby receive rotational motion provided by the motor  530 . The tubular actuating member  3058  may comprise a threaded nut  3059  for receiving the threaded drive shaft  3001  such that rotation of the threaded drive shaft  3001  causes the tubular actuating member  3058  to translate distally and proximally.  FIGS. 76-77  show additional view of one form of the axially movable member  3058  and tubular nut  3059 . In some forms, the tubular actuating member  3058  defines a cavity  3003 . The waveguide  3078  and/or a portion of the blade  3066  may extend through the cavity  3003 , as illustrated in  FIG. 74 . 
     In one example form, the distal end of the ultrasonic transmission waveguide  3078  may be coupled to the proximal end of the blade  3066  by an internal threaded connection, preferably at or near an antinode. It is contemplated that the blade  3066  may be attached to the ultrasonic transmission waveguide  3078  by any suitable means, such as a welded joint or the like. Although the blade  3066  may be detachable from the ultrasonic transmission waveguide  3078 , it is also contemplated that the single element end effector (e.g., the blade  3066 ) and the ultrasonic transmission waveguide  3078  may be formed as a single unitary piece. 
     The ultrasonic transducer  3016 , which is known as a “Langevin stack”, generally oscillates in response to an electric signal provided by a generator  3005  ( FIG. 74 ). For example, the transducer  3016  may comprise a plurality of piezoelectric elements or other elements for converting an electrical signal from the generator  3005  to mechanical energy that results in primarily a standing acoustic wave of longitudinal vibratory motion of the ultrasonic transducer  3016  and the blade  3066  portion of the end effector assembly  3026  at ultrasonic frequencies. The ultrasonic transducer  3016  may, but need not, have a length equal to an integral number of one-half system wavelengths (nλ/2; where “n” is any positive integer; e.g., n=1, 2, 3 . . . ) in length. A suitable vibrational frequency range for the transducer  3016  and blade  3066  may be about 20 Hz to 32 kHz and a well-suited vibrational frequency range may be about 30-10 kHz. A suitable operational vibrational frequency may be approximately 55.5 kHz, for example. 
     The generator  3005  may be any suitable type of generator located internal to or external from the surgical instrument  10 . A suitable generator is available as model number GEN11, from Ethicon Endo-Surgery, Inc., Cincinnati, Ohio. When the transducer  3016  is energized, a vibratory motion standing wave is generated through the waveguide  3078  and blade  3066 . The end effector  3026  is designed to operate at a resonance such that an acoustic standing wave pattern of predetermined amplitude is produced. The amplitude of the vibratory motion at any point along the transducer  3016 , waveguide  3078  and blade  3066  depends upon the location along those components at which the vibratory motion is measured. A minimum or zero crossing in the vibratory motion standing wave is generally referred to as a node (i.e., where motion is minimal), and a local absolute value maximum or peak in the standing wave is generally referred to as an anti-node (e.g., where local motion is maximal). The distance between an anti-node and its nearest node is one-quarter wavelength (λ/4). 
     In one example form, the blade  3066  may have a length substantially equal to an integral multiple of one-half system wavelengths (nλ/2). A distal end of the blade  3066  may be disposed near an antinode in order to provide the maximum longitudinal excursion of the distal end. When the transducer assembly is energized, the distal end of the blade  3066  may be configured to move in the range of, for example, approximately 10 to 500 microns peak-to-peak, and preferably in the range of about 30 to 64 microns at a predetermined vibrational frequency of 55 kHz, for example. 
     In one example form, the blade  3066  may be coupled to the ultrasonic transmission waveguide  3078 . The blade  3066  and the ultrasonic transmission waveguide  3078  as illustrated are formed as a single unit construction from a material suitable for transmission of ultrasonic energy. Examples of such materials include Ti6Al4V (an alloy of Titanium including Aluminum and Vanadium), Aluminum, Stainless Steel, or other suitable materials. Alternately, the blade  3066  may be separable (and of differing composition) from the ultrasonic transmission waveguide  3078 , and coupled by, for example, a stud, weld, glue, quick connect, or other suitable known methods. The length of the ultrasonic transmission waveguide  3078  may be substantially equal to an integral number of one-half wavelengths (nλ/2), for example. The ultrasonic transmission waveguide  3078  may be preferably fabricated from a solid core shaft constructed out of material suitable to propagate ultrasonic energy efficiently, such as the titanium alloy discussed above (i.e., Ti6Al4V) or any suitable aluminum alloy, or other alloys, for example. 
     In some forms, the surgical instrument  10  may also be utilized with other stapler-type end effectors. For example,  FIG. 78  illustrates one form of a linear staple end effector  3500  that may be used with the surgical instrument  10 . The end effector  3500  comprises an anvil portion  3502  and a translatable staple channel  3514 . The translatable staple channel  3514  is translatable in the distal and proximal directions, as indicated by arrow  3516 . A threaded drive shaft  3506  may be coupled to the output socket  238 , for example, as described herein above to receive rotational motion provided by the motor  530 . The threaded drive shaft  3506  may be coupled to a threaded nut  3508  fixedly coupled to the staple channel  3514  such that rotation of the threaded drive shaft  3506  causes translation of the staple channel  3514  in the directions indicated by arrow  3516 . The nut  3508  may also be coupled to a driver  3510 , which may, in turn, contact a staple cartridge  3512 . As it translates distally, the driver  3510  may push staples from the staple cartridge  3512  against the anvil  3502 , thus driving the staples through any tissue positioned between the staple channel  3514  and the anvil  3502 . 
     Also, in some forms, the surgical instrument may be utilized with a circular staple end effector.  FIG. 79  illustrates one form of a circular staple end effector  3520  that may be used with the surgical instrument  10 . The end effector  3520  comprises an anvil  3522  and a staple portion  3524 . A threaded drive shaft  3530  extends from the anvil  3522  through the staple portion  3524 . The threaded drive shaft  3530  may be coupled to the output socket  238 , for example, as described herein above to receive rotational motion provided by the motor  530 . A threaded nut  3532  may be coupled to the staple portion  3524  such that rotation of the threaded drive shaft  3530  alternately translates the staple portion  3524  distally and proximally as indicated by arrow  3534 . The threaded shaft may also be coupled to a driver  3528  such that distal motion of the staple portion  3524  pushes the driver  3528  distally into a staple cartridge  3526  to drive staples from the cartridge  3526  into any tissue positioned between the anvil  3522  and the staple portion  3524 . In some embodiments, the end effector  3520  may also comprise a knife or cutting implement  3535  for cutting tissue prior to stapling. 
     In addition to different end effectors, it will be appreciated that other implement portions may be interchangeable with respect to the surgical instrument  10 . For example, some forms of the surgical instrument  10  utilize different power cords.  FIG. 80  illustrates several example power cords  3540 ,  3542 ,  3544  for use with the surgical instrument. Each of the power cords  3540 ,  3542 ,  3544  comprises a socket  3546  for coupling to the surgical instrument  10 . The power cords  3540 ,  3542 ,  3544  may be utilized to connect the surgical instrument  10  to various power sources. For example power cords  3540  and  3542  comprise sockets  3550 ,  3552  to be received by generators, such as the model number GEN11 generator, from Ethicon Endo-Surgery, Inc., in Cincinnati, Ohio. Such a generator may provide power to the instrument  10  and/or may provide a signal to drive an electrosurgical and/or ultrasonic end effector. Power cord  3544  comprises a plug  3548  that may be plugged into a wall socket to provide power to the instrument  10  (e.g., in lieu of the battery  802 ). 
     In some forms, the surgical instrument may also comprise interchangeable implement portions that include different shafts.  FIG. 81  illustrates several example shafts  3554 ,  3556 ,  3558  that can be used with the surgical instrument  10 . Each shaft  3554 ,  3556 ,  3558  comprises a detachable drive mount portion  700 ′,  700 ″,  700 ′″ similar to the detachable drive mount portion  700  that may be received by the instrument  10  as described herein above. Each shaft  3554 ,  3556 ,  3558  also comprises a coupler assembly  3557  for receiving an end effector similar to the coupler assembly  200  described herein above. In some embodiments, different shafts are configured to receive different types of end effectors at the coupler assembly  3557 . The shafts  3554 ,  3556 ,  3558  may each comprise different characteristics including, for example, different lengths, the presence or absence of articulation, passive or active articulation, different degrees of articulation, different diameters, different curvatures, etc. For example, the shaft  3554  defines a curve  3559  off the center axis of the shaft. The shaft  3558  defines an articulation joint  3560  that may be articulated in a manner similar to that described herein above with respect to the articulation joint  310 . 
     It will be appreciated that different kinds of implement portions  100  (e.g., power cords, shafts, end effectors, etc.) require the various motors and other components of the surgical instrument  10  to operate in different ways. For example, powered end effectors, such as the electrosurgical end effector  3156  and ultrasonic end effector  3026 , require an energy signal for powering electrodes and/or ultrasonic blades. Different end effectors may also require different motion of the various motors  402 ,  560 ,  530 ,  610  for actuation, including, for example, the actuation of different motors, the provision of different amounts of torque, etc. In various forms, the implement portions  100  may provide the surgical instrument  10  with control parameters. 
       FIG. 82  is a block diagram of the handle assembly  20  of the surgical instrument  10  showing various control elements. The control elements shown in  FIG. 82  are configured to receive control parameters from various implement portions and control the surgical instrument  10  based on the received control parameters and based on one or more input control signals received from the clinician (e.g., via the joystick control  840  or other suitable actuation device). The control elements may comprise a control circuit  3702  for controlling the surgical instrument  10 . In various forms, the control circuit  3702  may execute a control algorithm for operating the surgical instrument  10  including any installed implement portions. In some forms, the control circuit  3702  is implemented on the proximal circuit board  820  described herein above. The control circuit  3702  comprises a microprocessor  3706  and associated memory and/or data storage  3708 . In some forms the control circuit  3702  may also comprise a generator circuit  3704  for providing a power signal to an ultrasonic and/or electrosurgical device. The generator circuit  3704  may operate as a stand-alone component or in conjunction with an external generator. 
       FIG. 82  also shows motors  3714 , which may correspond to the motors  402 ,  560 ,  530 ,  610  described above. A battery  3713  may correspond to the battery  802  described herein above. Input to the control circuit  3702  may be provided by the joystick control  840  or other suitable actuation device. The various surgical implement portions  100  described herein may be coupled to the handle  20  at respective sockets  3710 ,  3712 . The socket  3712  may receive a shaft, such as the shafts  3554 ,  3556 ,  3558 . For example, the socket  3712  may receive a shaft in a manner similar to the way that the handle  20  receives the detachable derive mount  700  as described herein above. The socket  3710  may be configured to receive a cord socket, such as the sockets  3546  described herein above. 
     The control circuit  3702 , in conjunction with various other control elements such as the sockets  3710 ,  3712 , may receive control parameters from various installed implement portions. Control parameters may comprise, for example, data describing properties of the implement portions, data describing algorithms for operating the instrument  10  with the implement portions installed, etc. Sockets  3710 ,  3712  may mechanically and communicatively couple to the various implement portions. For example, various implement portions may comprise circuits  3720  for storing control parameters. Such circuits  3720  are shown in conjunction with the power cords  3540 ,  3542 ,  3544  in  FIG. 80  and in conjunction with the shafts  3554 ,  3556   3558  of  FIG. 81 . Also,  FIG. 83  illustrates one form of various end effector implement portions  3730 ,  3732 ,  3734 ,  3736 ,  3738  comprising circuits  3720  as described herein. The circuits  3720  may comprise one or more data storage components for storing control parameters for provision to the control circuit  3702 . Such data storage components can include any suitable type of memory device (e.g., electrically erasable programmable read only memory (EEPROM), digital register, any other type of memory, etc.). Memory devices may also include coils or other hardware components configured to modulate predetermined control parameters, for example, in response to a radio frequency identification (RFID) interrogation signal. In some forms, the circuits  3720  make a direct wired connection to the control circuit  3702 , for example, via respective sockets  3710 ,  3712 . Accordingly, the control circuit  3702  may directly communicate with the various circuits  3720  to receive control parameters. 
     In some forms, the circuits  3720  comprise passive or active RFID devices. The handle  20  may comprise one or more antennas  3716 ,  3718 , which may be positioned at or near the respective sockets  3710 ,  3712 . Utilizing the antennas  3716 ,  3718 , the control circuit  3702  may interrogate the circuits  3720  on installed implement portions to retrieve the control parameters. In some forms, the control circuit  3702  is programmed to interrogate the various implement portions upon start-up and/or upon an indication that an implement portion has been installed and/or removed. In response the control circuit  3702  may receive a reflected signal from the RFID device. The reflected signal may indicate the relevant control parameters. In some forms, the circuits  3720  may comprise active RFID devices that transmit the data describing their associated implement portions, for example, upon installation. 
     As illustrated in  FIG. 81 , some shaft forms may comprise antennas  3719  at distal portions. The antennas  3719  may be in communication with the control circuit  3702  via conductors (not shown) extending through the respective shafts allowing the control circuit  3702  to interrogate RFID device circuits  3720  on end effectors, such as end effectors  3730 ,  3732 ,  3734 ,  3736 ,  3738 . In some forms, antennas  3718  positioned in the handle may receive and transmit sufficient power so as to interrogate an RFID device circuit  3720  on an end effector without the requiring a separate antenna  379  in the shaft. In some arrangements, the circuits  3720  may be configured to make a wired connection to the control circuit  3702 . For example, antennas  3716 ,  3718 ,  3719  may be omitted. 
       FIG. 84  is a block diagram showing one form of a control configuration  3800  to be implemented by the control circuit  3702  to control the surgical instrument  10 . According to the configuration  3800 , the control circuit  3702  is programmed with a control algorithm  3802 . The control algorithm  3802  receives control parameters from installed implement portions in the form of input variables  3801 . The input variables  3801  may describe properties of installed implement portion. The control algorithm  3802  also receives one or more input control signals  3818  (e.g., from the joystick control  840 , a robotic system, or other suitable actuation device operated by a clinician). Based on the input variables  3801 , the control algorithm  3802  may operate the surgical instrument  10  by translating the one or more input control signals  3818  to an output motor control signal  3814  for controlling the motors  3714  and an optional output energy control signal  3816  for controlling an ultrasonic and/or electrosurgical end effector. It will be appreciated that not all forms of the surgical instrument  10  need receive input variables from all of the listed implement portions. For example, some forms of the surgical instrument comprise a single shaft and/or a fixed end effector. Also, some forms of the surgical instrument (or configurations thereof) may omit a power cord. 
     The control algorithm  3802  may implement a plurality of functional modules  3804 ,  3806 ,  3810 ,  3812  related to different aspects of the surgical instrument  10 . A firing module  3804  may translate the one or more input control signals  3818  to one or more output motor control signals  3814  for controlling the respective motors  3714  to fire the instrument  10 . An articulation module  3806  may translate the one or more input control signals  3818  to one or more output motor control signals  3814  for articulating the shaft of the instrument  10 . The power module  3812  may route power to the various components of the surgical instrument  10 , as required by an installed power cord. For forms of the instrument  10  utilizing energy at the end effector (e.g., ultrasonic and/or electrosurgical instruments), an energy module  3810  may translate the one or more input control signals  3818  into output energy signals  3816  to be provided to the end effector. The energy signals  3816  may be produced by the generator  3704  and/or by an external generator (not shown in  FIG. 84 ) and may be provided to a transducer  3016  and/or energy delivery surfaces  3204 A,  3204 B at the end effector. 
     The various modules  3804 ,  3806 ,  3810 ,  3812  of the control algorithm  3802  may utilize control parameters in the form of input variables  3801  to translate the one or more input control signals  3818  into output signals  3814 ,  3816 . For example, input variables  3801  received from different implement portions may affect the control algorithm  3802  in different ways. Input variables  3801  received from power cord, such as  3540 ,  3542 ,  3544  may include, for example, a cord type, whether the cord is connected to an external object such as a generator or power socket, the identity of the external object to which the cord is connected, etc. One type of power cord, such as cord  3544 , may be configured to receive power from an external power socket, such as a wall outlet. When the control circuit  3702  determines that a cord of this type is installed (e.g., at socket  3710 ), the power module  3812  may be programmed to configured the control circuit  3702  to power the motors  3714  and/or energy elements from power provided through the installed cord implement. Power provided through the installed cord implement may be used in addition to or instead of power provided by the battery  3713 . 
     Another type of cord, such as  3540  and  3542 , may be configured to communicate with an external generator. The power module  3812  and/or energy module  3810  may configured the control circuit  3702  to power the energy element based on an energy signal received via the installed power cord. In addition, the energy module  3810  may configure the control circuit  3702  to provide input to the generator via the installed power cord. Such input may include, for example, an input control signal  3818  indicating that the clinician has requested energy. In some forms, the input variables  3801  received from the power cord may also indicate a type of generator that the power cords is configured to (and/or is) coupled to. Example generators may include stand-alone electrosurgical generators, stand-alone ultrasonic generators, combined electrosurgical/ultrasonic generators, etc. In some forms, the input variables  3801  received from the cord may also indicate a type of generator with which the cord is configured to couple. In some forms, the type of generator indicated may affect the operation of the control algorithm  3802 . For example, different generator types may have different control interfaces and expect different forms of instructions from the surgical instrument  10  and/or provide outputs in different forms. 
     When the shaft, such as one of shafts  3554 ,  3556 ,  3558 , is a removable implement portion, input variables  3801  received from the shaft may indicate various properties of the shaft. Such properties may include, for example, a length of the shaft, a position and degree of curvature of the shaft (if any), parameters describing an articulation joint of the shaft (if any), etc. The length of the shaft and the position and degree of curvature of the shaft may be utilized, for example, by the firing module  3804  and/or by the articulation module  3806  of the control algorithm  3802  to determine torque requirements and/or tolerances. The parameters describing the articulation joint of the shaft may indicate, or allow the articulation module  3806  to derive, various motor motions required to articulate the shaft in different directions. In some embodiments, the input variables  3801  may also indicate a degree of allowable articulation, which the articulation module  3806  may translate into a maximum allowable motor movement. In some forms, input variables  3801  received from the shaft may also indicate whether the installed shaft supports shaft rotation and/or end effector rotation. Such variables  3801  may be utilized by the control algorithm  3802  to derive which motor or motors  3714  are to be actuated for shaft and/or end effector rotation, the torque and number of rotations indicated for each motor  3714 , etc. 
     Input variables  3801  received from end effector implement portions may be of different forms based on the type of end effector used. For example, endocutters and other stapler end effectors, such as the end effector  102  described herein above, may provide variable values indicating the length of the end effector (e.g., 45 mm or 60 mm staple line), whether the anvil and elongate channel are straight or curved, the motor  3714  to which a drive shaft, such as drive shaft  180 , is coupled, etc. Such input variables  3801  may be utilized by the firing module  3804  to translate input control signals  3818  requesting firing of the instrument  10  to output motor control signals  3814 . For example, the length, curvature, etc. of the end effector may determine the motor  3714  to be activated, the amount of force or torque required to be provided, the number of motor rotations required to fire, etc. Similarly, input variables  3818  received from linear or circular stapler end effectors, such as  3500  and  3520 , may be utilized by the firing algorithm  3804  to determine the motor  3714  to be actuated to fire, the amount of force or torque required to be provide in response to different levels of the input control signal  3818  related to firing, the number of motor rotations required to fire, etc. 
     When the end effector is an energy end effector, such as the electrosurgical end effector  3156  or the ultrasonic end effector  3026 , the received input variables  3801  may describe information relating to the closure motion of the end effector, as well as information describing the energy elements including, for example, the timing of energy provision in the context of the firing stroke. The information describing the closure motion may be utilized, for example, by the firing module  3804  to determine which motor or motors  3714  are to be actuated for firing and/or retraction, the torque and number of rotations indicated for each motor  3714 , etc. Information describing the energy elements may be utilized, for example, by the energy module  3810  to generate the output energy signal  3816 . For example, the energy module  3810  may determine what type of output energy signal  3816  is required (e.g., voltage, current, etc.), whether the signal can be generated by an internal generator  3704 , whether there are any lock-outs to be implemented with the signal. Example lock-outs may prevent the firing motion from taking place unless energy is being provided and/or may prevent energy from being provided unless the firing motion is taking place. In some embodiments, the energy module  3810  may also derive the timing of the output energy signal  3816  in the context of the instrument&#39;s firing stroke. For example, referring to the electrosurgical end effector  3156 , the energy module  3810  may derive how long the energy delivery surfaces  3204 A,  3204 B should be activated before the tissue cutting element  3210  is advanced. 
       FIG. 85  is a flowchart showing one example form of a process flow  3600  for implementing the control algorithm  3802  with the control circuit  3702 . At  3602 , the control circuit  3702  may receive an indication of the presence of an implement portion (e.g., a power cord, shaft, end effector, etc.). The indication may be generated automatically upon installation of the implement portion. For example, in forms where the implement portion comprises an active RFID, the indication of the presence of the implement portion may be provided by the active RFID. Also, in some embodiments, the socket  3710 ,  3712  by which the implement portion is connected to the instrument  10  may comprise a switch that indicates the presence of the implement portion. At  3604 , the control circuit  3702  may interrogate the implement portion for input variables  3801 . When the implement portion comprises a passive RFID device, the interrogation may comprise illuminating the RFID device with a radio frequency signal. When the implement portion is in wired communication with control circuit,  3702 , the interrogation may comprise sending a request to a memory device associated with the implement portion. 
     At  3606 , the control circuit  3702  may receive input variables  3801  from the implement portion. The input variables  3801  may be received in any suitable manner. For example, when the implement portion comprises a passive RFID device, the input variables  3801  may be derived by demodulating a return signal from the RFID device. When there is a wired connection between the implement portion and the circuit  3702 , the input variables  3801  may be received directly from a memory device at the implement portion, etc. At  3608 , the control circuit  3702  may apply the input variables  3801  to the control algorithm  3802 , for example, as described herein above. This may have the effect of configuring the pre-existing algorithm  3802  to operate the instrument  10  with whatever implement portion or portions are installed. 
       FIG. 86  is a block diagram showing another form of a control configuration  3900  to be implemented by the control circuit  3702  to control the surgical instrument  10 . In the configuration  3900 , the control parameters received from the various implement portions comprise algorithms for controlling the respective implement portions. The control circuit  3702  implements a shell control algorithm  3902  comprising an operating system  3904 . The operating system  3904  is programmed to interrogate installed implement portions to receive control parameters, in the form of implement algorithms  3906 . Each implement algorithm  3906  may describe a manner of translating input control signals  3908  into output motor control signals  3910  and output energy signals  3912 . Upon receiving the implement algorithms  3906 , the operating system  3904  may execute the algorithms  3906  to operate the instrument  10 . 
     In some embodiments, the operating system  3904  may also reconcile the various algorithms  3906 . For example, an implement algorithm  3906  received from an energy end effector may take different configurations based on whether the instrument is in communication with an external generator, or utilizing the internal generator  3704 . Accordingly, the operating system  3904  may configure an implement algorithm  3906  for an energy end effector based on whether an implement algorithm  3906  has been received from a corresponding power cord configured to couple with an external generator. Also, in some forms, the tolerances and/or number of rotations necessary for firing an end effector may depend on the configuration of the shaft. Accordingly, the operating system  3904  may be configured to modify the implement algorithm  3906  received from an end effector based on a corresponding implement algorithm  3906  received from a shaft. 
       FIG. 87  is a flowchart showing one example form of a process flow  3400  for implementing the control algorithm  3902  utilizing the control circuit  3702 . At  3402 , the control circuit  3702  may execute the operating system  3904 . The operating system  3904  may program the control circuit  3702  to take various other actions described herein with respect to the control configuration  3900 . At  3404 , the control circuit  3702  may interrogate one or more implement portions installed with the surgical instrument  10 , for example, as described herein. At  3406 , the control circuit  3702  may receive implement algorithms  3906 , as described herein. At  3408 , the control circuit  3702  may apply the received algorithms  3906  to operate the surgical instrument. Applying the received algorithms  3906  may include, for example, reconciling the algorithms  3906 , as described herein above. 
       FIGS. 88 and 89  illustrate one form of a surgical instrument  4010  comprising a sensing module  4004  located in the end effector  4002 . In some forms, the surgical instrument  4010  may be similar to the surgical instrument  10  and the end effector  4002  may be similar to the end effector  102  described above. The sensing module  4004  may be configured to measure one or more conditions at the end effector  4002 . For example, in one arrangement, the sensing module  4004  may comprise a tissue-thickness sensing module that senses the thickness of tissue clamped in the end effector  4002  between the staple cartridge  130  and the anvil assembly  190 . The sensing module  4004  may be configured to generate a wireless signal indicative of the one or more measured conditions at the end effector  4002 . According to one arrangement shown in  FIG. 89 , the sensing module  4004  may be located at a distal end of the end effector  4002 , such that the sensing module  4004  is out of the way of the staples of the staple cartridge  130  when the staples are fired. In various forms, the sensing module  4004  may comprise a sensor, a radio module, and a power source. See  FIG. 90 . The sensor may be disposed in the distal end of the end effector  4002  (as shown in  FIG. 89 ), at the powered articulation joint  310 , or any other suitable portion of the implement portion  100 . 
     In various arrangements, the sensor may comprise any suitable sensor for detecting one or more conditions at the end effector  4002 . For example, and without limitation, a sensor located at the distal end of the end effector  4002  may comprise a tissue thickness sensor such as a Hall Effect Sensor or a reed switch sensor, an optical sensor, a magneto-inductive sensor, a force sensor, a pressure sensor, a piezo-resistive film sensor, an ultrasonic sensor, an eddy current sensor, an accelerometer, a pulse oximetry sensor, a temperature sensor, a sensor configured to detect an electrical characteristic of a tissue path (such as capacitance or resistance), or any combination thereof. As another example, and without limitation, a sensor located at the powered articulation joint  310  may comprise a potentiometer, a capacitive sensor (slide potentiometer), piezo-resistive film sensor, a pressure sensor, a pressure sensor, or any other suitable sensor type. In some arrangements, the sensing module  4004  may comprise a plurality of sensors located in multiple locations in the end effector  4002 . The sensing module  4004  may further comprise one or more visual markers to provide a visual indication, such as through a video feed, to a user of the current condition at the end effector  4002 . 
     The sensing module  4004  may comprise a radio module configured to generate and transmit a wireless signal indicative of the measured condition at the end effector  4002 . See  FIG. 90 . The radio module may comprise an antenna configured to transmit the wireless signal at a first frequency. The transmission power of the sensing module  4004  may be limited by the size of the antenna and the power source locatable in the sensing module  4004 . The size of the end effector  4002  may reduce the available space for placing an antenna or a power source powerful enough to transmit a signal from the sensing module  4004  to a remote location, such as, for example, a video monitor  4014 . Due to the constrained size of the antenna and the low power delivered by the power source to the sensing module  4004 , the sensing module  4004  may produce a low-power signal  4006  capable of transmission over short distances. For example, in some forms the sensing module  4004  may transmit a signal from the end effector  4002  to the relay station  4008  located proximally from the end effector  4002 . For example, the relay station  4008  may be located at the handle  4020  of the instrument  4010 , in the shaft  4030  (e.g., a proximal portion of the shaft  4030 ), and/or in an implantable device positioned on or within the patient. 
     The relay station  4008  may be configured to receive the low-power signal  4006  from the sensing module  4004 . The low-power signal  4006  is limited by the size of the antenna and the power source that may be located in the end effector  4002  as part of the sensing module  4004 . The relay station  4008  may be configured to receive the low-power signal  4006  and retransmit the received signal as a high-power signal  4012 . The high-power signal  4012  may be transmitted to remote network or device, such as a video monitor  4014  configured to display a graphical representation of the measured condition at the end effector  4002 . Although the sensing module  4004  and the relay station  4008  have generally been described in relation to the surgical instrument  4010 , those skilled in the art will recognize that the sensing module  4004  and relay station  4008  arrangement may be used with any suitable surgical system, such as, for example, a robotic surgical system. For example, the relay station  4008  may be positioned in a shaft and/or instrument portion of the robotic surgical instrument. A suitable robotic surgical system is described in U.S. patent application Ser. No. 13/538,700, entitled SURGICAL INSTRUMENTS WITH ARTICULATING SHAFTS, now U.S. Pat. No. 9,408,622, which is herein incorporated by reference in its entirety. 
     In some forms, the video monitor  4014  may comprise a stand-alone unit for displaying the measured condition at the end effector  4002 , a standard viewing monitor for use in endoscopic, laparoscopic, or open surgery, or any other suitable monitor. The displayed graphical representation may be displayed overtop of a video feed or other information displayed on the video monitor. In some forms, the high-power signal  4012  may interrupt the video monitor  4014  display and may cause the video monitor to display only the graphical representation of the measured condition at the end effector  4002 . A receiver module  4015  may be interfaced with the video monitor  4014  to allow the video monitor  4014  to receive the high-power signal  4012  from the relay station  4008 . In some arrangements, the receiver module  4015  may be formed integrally with the video monitor  4014 . The high-power signal  4012  may be transmitted wirelessly, through a wired connection, or both. The high-power signal  4012  may be received by a wide-area network (WAN), a local-area network (LAN), or any other suitable network or device. 
     In some forms, the video monitor  4014  may display images based on data contained in the received high-power signal  4012 . For example, the clinician may see real-time data regarding the thickness of the clamped tissue throughout a procedure involving the surgical instrument  4010 . The video monitor  4014  may comprise a monitor, such as a cathode ray tube (CRT) monitor, a plasma monitor, a liquid-crystal display (LCD) monitor, or any other suitable visual display monitor. The video monitor  4014  may display a graphical representation of the condition at the end effector  4002  based on the data contained in the received high-power signal  4012 . The video monitor  4014  may display the condition at the end effector  4002  in any suitable manner, such as, for example, overlaying a graphical representation of the condition at the end effector over a video feed or other data displayed on the video monitor  4014 . In some forms, the video monitor  4014  may be configured to display only data received from the high-power signal  4012 . Similarly, the high-powered signal  4012  may be received by a computer system (not shown). The computer system may comprise a radio-frequency module (such as, for example, receiver module  4015 ) for communication with the relay station  4008 . The computer system may store the data from the high-power signal  4012  in a memory unit (e.g., a ROM or hard disk drive) and may process the data with a processor. 
     In some forms, the relay station  4008  amplifies the power of the low-power signal  4006  to a high-power signal  4012  but does not otherwise alter the low-power signal  4006 . The relay station  4008  may be configured to retransmit the high-power signal  4012  to a remote network or device. In some arrangements, the relay station  4008  may alter or process the received low-power signal  4006  before retransmitting the high-power signal  4012 . The relay station  4008  may be configured to convert the received signal from a first frequency transmitted by the sensing module  4004  into a second frequency receivable by a remote network or device, such as the video monitor  4014 . For example, in one arrangement, the sensing module  4004  may transmit the low-power signal  4006  using a first frequency comprising a human-tissue permeable frequency. A human-tissue permeable frequency may comprise a frequency configured to pass through human tissue with minimal attenuation of the signal. For example, a frequency may be chosen outside of a water absorption band to limit the attenuation of the signal by human tissue (which may comprise a high percentage of water). For example, the sensing module  4004  may use the Medical Implant Communication Service (MICS) frequency band (402-405 MHz), a suitable industrial, scientific, and medical (ISM) radio band (such as 433 MHz center frequency or 915 MHz center frequency), a near field communication band (13.56 MHz), a Bluetooth communication band (2.4 GHz), an ultrasonic frequency, or any other suitable, human-tissue permeable frequency or frequency band. The relay station  4008  may receive the low-power signal  4006  in the first frequency. The relay station  4008  may convert the low-power signal  4006  from the first frequency to a second frequency that is suitable for transmission through air over long ranges. The relay station  4008  may use any suitable frequency to transmit the high-power signal  4012 , such as, for example, a Wi-Fi frequency (2.4 GHz or 5 GHz). 
     In some forms, the relay station  4008  may convert the received low-power signal  4006  from a first communication protocol to a second communication protocol prior to transmission of the high-power signal  4012 . For example, the sensing module  4004  may transmit the low-power signal  4006  using a first communication protocol, such as, for example, a near field communication (NFC) protocol, a Bluetooth communication protocol, a proprietary communication protocol, or any other suitable communication protocol. The relay station  4008  may receive the low-power signal  4006  using the first communication protocol. The relay station  4008  may comprise a protocol conversion module to convert the received signal from the first communication protocol to a second communication protocol, such as, for example, TCP/IP, UDP, or any other suitable communication protocol. 
       FIG. 90  is a block diagram showing a sensing module  4104 , which represents an example arrangement of the sensing module  4004  described herein above. The sensing module  4104  may comprise a sensor  4116 , a controller  4118 , a radio module  4124 , and a power source  4126 . The controller  4118  may comprise a processor unit  4120  and a memory unit  4122 . The senor  4116  may be disposed in the distal end of the end effector  4002  (as shown in  FIG. 89 ), at articulation joint  310 , or any other suitable portion of the implement portion  100 . In various forms, the sensor  4116  may comprise any suitable sensor for detecting one or more conditions at the end effector. 
     In some arrangements, the sensor  4116  may comprise a tissue thickness sensor, such as, for example, a Hall Effect sensor. The tissue thickness sensor may detect the thickness of tissue clamped in the end effector  4002  based on a magnetic field generated by a magnet  4042  located, for example, at a distal end of the anvil assembly  190 . See  FIG. 89 . When the clinician closes the anvil assembly  190 , the magnet  4042  rotates downwardly closer to the sensing module  4004 , thereby varying the magnetic field detected by the sensing module  4004  as the anvil assembly  190  rotates into the closed (or clamped) position. The strength of the magnetic field from the magnet  4042  sensed by the sensing module  4004  is indicative of the distance between the channel  130  and the anvil assembly  190 , which is indicative of the thickness of the tissue clamped between the channel  130  and the anvil assembly  190  when the end effector  4002  is in the closed (or clamped) position. 
     The sensing module  4104  may be configured to generate a wireless signal indicative of the measured condition at the end effector. The wireless signal may be generated by the radio module  4124 . In some forms, the transmission power of the radio module  4124  is limited by the size of an antenna included in the radio module  4124  and the size of a power source  4126  located in the sensing module  4104 . The size of the end effector  4002  may reduce the available space for placing an antenna or a power source  4126  powerful enough to transmit a signal from the sensor  4116  to a remote location, such as, for example, a video monitor  4014 . Due to the limitations on the antenna and the low power delivered by the power source  4126 , the radio module  4124  may only produce a low-power signal  4006  capable of transmission over short distances, such as the distance to the proximal end of the shaft  4030 . For example, in one form, the radio module  4124  may transmit the low-power signal  4006  from the end effector  4002  to the handle  4020  of the surgical instrument  4010 . In some arrangements, a power source  4126  capable of delivering higher power levels may generate a low-power signal  4006  to prolong operation of the surgical instrument  4010 . 
     The memory unit  4122  of the controller  4118  may comprise one or more solid state read only memory (ROM) and/or random access memory (RAM) units. In various arrangements, the processor  4120  and the memory unit(s)  4122  may be integrated into a single integrated circuit (IC), or multiple ICs. The ROM memory unit(s) may comprise flash memory. The ROM memory unit(s) may store code instructions to be executed by the processor  4120  of the controller  4118 . In addition, the ROM memory unit(s)  4122  may store data indicative of the cartridge type of the cartridge  130 . That is, for example, the ROM memory unit(s)  4122  may store data indicating the model type of the staple cartridge  130 . In some arrangements, a controller in the handle  4020  of the surgical instrument  4010  may utilize the condition information and model type of the staple cartridge  130  to detect proper operation of the surgical instrument  4010 . For example, the sensing module  4004  may be configured to measure tissue thickness. The tissue thickness information and the cartridge model type may be used to determine if the tissue clamped in the end effector  4002  is too thick or too thin, based on the specified tissue thickness range for the particular staple cartridge  130 . The radio module  4124  may be a low power, 2-way radio module that communicates wirelessly, using a wireless data communication protocol, with the relay station  4008  in the handle  4020  of the surgical instrument  4010 . The radio module  4124  may comprise any suitable antenna for transmission of the low-power signal  4006 . For example, the radio module  4124  may comprise a dipole antenna, a half-wave dipole antenna, a monopole antenna, a near field communication antenna, or any other suitable antenna for transmission of the low-power signal  4006 . The size of the antenna, and therefore the available transmission power and frequencies, may be limited by the size of the end effector  4002 . 
     According to various forms, the radio module  4124  may communicate with the relay station  4008  using a human-tissue permeable frequency. For example, the communications between the radio module  4124  and the relay station  4008  may use the Medical Implant Communication Service (MICS) frequency band (402-405 MHz), a suitable industrial, scientific, and medical (ISM) radio band (such as 433 MHz center frequency or 915 MHz center frequency), a Near Field communication band (13.56 MHz), a Bluetooth communication band (2.4 GHz), an ultrasonic frequency, or any other suitable, human-tissue-permeable frequency or frequency band. The power source  4126  may comprise a suitable battery cell for powering the components of the sensing module  4004 , such as a Lithium-ion battery or some other suitable battery cell. 
     In some forms, the components of the sensing module  4104  may be located in the end effector  4002 , on the shaft  4030 , or in any other suitable location of the surgical instrument  4010 . For example, the sensor  4116  may be located in the distal end of the end effector  4002 . The controller  4118 , the radio module  4124 , and the power source  4126  may be located on the shaft  4030 . One or more wires may connect the sensor  4116  to the controller  4118 , the radio module  4124 , and the power source  4126 . In some forms, the functions of the end effector  4002  and the shaft  4030  may limit the placement of the sensing module  4104 . For example, in the illustrated form, the end effector  4002  is articulatable and rotatable through the powered articulation joint  310 . Placing wires over the powered articulation joint  310  may result in twisting or crimping of the wires and may interfere with the operation of the powered articulation joint  310 . The placement of the sensing module  4004  components may be limited to a location distal of the powered articulation joint  310  to prevent operational issues of the articulation joint  310  or of the sensing module  4004 . 
     In some arrangements, the sensing module  4104  may comprise an analog to digital convertor (ADC)  4123 . The sensor  4116  may generate an analog signal representative of a condition at the end effector  4002 . Transmission of the signal representative of a condition at the end effector  4002  wirelessly may require conversion of the analog signal to a digital signal. The analog signal produced by the sensor  4116  may be converted into a digital signal by the ADC  4123  prior to the generation and transmission of the low-power signal  4006 . The ADC  4123  may be included in the controller  4118  or may comprise a separate controller, such as, for example, a microprocessor, a programmable gate-array, or any other suitable ADC circuit. 
       FIG. 91  is a block diagram showing a relay station  4208 , which represents one example arrangement of the relay station  4008  described herein above. The relay station  4208  may be located proximal to the shaft, such as, for example, in close proximity with a battery  4226 , and spaced away from the sensing module  4004  in the end effector  4002  by, for example, the shaft  4030 . For example, the relay station  4208  may be located in the handle  4020  of the surgical instrument  4010 . As such, the relay station  4208  may receive a wireless signal from the sensing module  4004 . The relay station  4208  may comprise a releasable module that may be selectively interfaced with the handle  4020  of the surgical instrument  4002 . 
     As shown in  FIG. 91 , the relay station  4208  may comprise a radio module  4228  and an amplification module  4230 . In some arrangements, the radio module  4228  is configured to receive the low-power signal  4006 . The low-power signal  4006  may be transmitted from the sensing module  4004  and is indicative of a condition at the end effector  4002 . The radio module  4228  of the relay station  4208  receives the low-power signal  4006  and provides the low-power signal  4006  to an amplification module  4230 . The amplification module  4230  may amplify the low-power signal  4006  to a high-power signal  4012  suitable for transmission over a longer range than the low-power signal  4006 . After amplifying the received low-power signal  4006  to the high-power signal  4012 , the amplification module  4230  may provide the high-power signal  4012  to the radio module  4228  for transmission to a remote network or device, such as, for example, the video monitor  4014 . The amplification module  4230  may comprise any suitable amplification circuit, for example, a transistor, an operational amplifier (op-amp), a fully differential amplifier, or any other suitable signal amplifier. 
       FIG. 92  is a block diagram showing a relay station  4308 , which represents another example arrangement of the relay station  4008  described herein above. In the illustrated form, the relay station  4308  comprises a radio module  4328 , an amplification module  4330 , and a processing module  4336 . The amplification module  4330  may amplify the received low-power signal  4006  prior to processing by the processing module  4336 , after the processing module  4336  has processed the received low-power signal  4006 , or both prior to and after processing by the processing module  4336 . The radio module  4328  may comprise a receiver module  4332  and a transmitter module  4334 . In some forms, the receiver module  4332  and the transmitter module  4334  may be combined into a signal transceiver module (not shown). The receiver module  4332  may be configured to receive the low-power signal  4006  from the sensing module  4004 . The receiver module  4332  may provide the received low-power signal  4006  to the processing module  4336 . 
     In the illustrated arrangement, the processing module  4336  comprises a frequency conversion module  4338  and a protocol conversion module  4340 . The frequency conversion module  4338  may be configured to convert the received low-power signal  4006  from a first frequency to a second frequency. For example, the sensing module  4004  may transmit the low-power signal  4006  using a first frequency that is suitable for transmission through human tissue, such as a MICS or an ISM frequency. The receiver module  4332  may receive the low-power signal  4006  in the first frequency. The frequency conversion module  4338  may convert the low-power signal  4006  from the first frequency to a second frequency that is suitable for transmission through air over long ranges. The frequency conversion module  4338  may convert the received low-power signal  4006  into any suitable frequency for transmission of the high-power signal, such as, for example, a Wi-Fi frequency (2.4 GHz or 5 GHz frequencies). 
     The protocol conversion module  4340  may be configured to convert the received signal from a first communication protocol to a second communication protocol. For example, the sensing module  4004  may transmit the low-power signal  4006  using a first communication protocol, such as, for example, a near field communication (NFC) protocol, a Bluetooth communication protocol, a proprietary communication protocol, or any other suitable communication protocol. The relay station  4308  may receive the low-power signal  4006  using the first communication protocol. The relay station  4308  may comprise a protocol conversion module  4340  to convert the received low-power signal  4006  from the first communication protocol to a second communication protocol, such as, for example, a TCP/IP protocol, a Bluetooth protocol, or any other suitable communication protocol. The processing module  4336 , including the frequency conversion module  4338  and the protocol conversion module  4340 , may comprise one or more microprocessors, programmable gate-arrays, integrated circuits, or any other suitable controller or any combination thereof. 
     In some forms, the frequency conversion module  4338  and/or the protocol conversion module  4340  may be programmable. Networks, video monitors, or other receiving equipment may be configured to receive signals at a specific frequency and in a specific protocol. For example, a local-area network (LAN) may be configured to receive a wireless signal using the 802.11 wireless standard, requiring a transmission at a frequency of 2.4 GHz or 5 GHz and using a TCP/IP communication protocol. A user may select the 802.11 wireless communication standard from a plurality of communication standards stored by the relay station  4308 . A memory module may be included in the relay station  4308  to store the plurality of communication standards. A user may select a communication standard for the high-power signal  4012  from the plurality of communication standards stored by the memory module. For example, a user may select the 802.11 communication standard as the communication standard for the transmission of the high-power signal  4012 . When a communication standard is selected by a user, the frequency conversion module  4338  or the protocol conversion module  4340  may be programmed by the memory module to convert the received low-power signal  4006  into the selected communication standard by converting the frequency or communication protocol of the received low-power signal  4006 . In some arrangements, the relay station  4308  may automatically detect the proper frequency and communication protocol for receiving the low-power signal  4006  or transmitting the high-power signal  4012 . For example, the relay station  4308  may detect a hospital wireless communication network. The relay station  4308  may automatically program the frequency conversion module  4338  and protocol conversion module  4340  to convert the received low-power signal  4006  into the proper frequency and protocol for communication of the high-power signal  4012  to the hospital wireless communication network. 
     In the illustrated form, the processing module  4336  may provide the processed signal to an amplification module  4330  for amplification of the processed signal to a high-power signal  4012  prior to transmission. The amplification module  4330  may amplify the processed signal to a suitable level for transmission by a transmission module  4334 . The amplification module  4330  may comprise any suitable amplification circuit, for example, a transistor, an operational amplifier (op-amp), a fully differential amplifier, or any other suitable electronic amplifier. The amplification module  4330  may comprise a battery (not shown) or may be connected to a power source  4326  located within the handle  4020  of the surgical instrument  4010 . The amplification module  4330  may be programmable to provide one or more amplification levels in response to the selection of a specific communication type. 
     The amplification module  4330  may provide the high-power signal  4012  to the transmission module  4334  for transmission. Although the radio module  4328 , the processing module  4336 , and the amplification module  4330  are shown as separate modules, those skilled in the art will recognize that any or all of the illustrated modules may be combined into a signal integrated circuit or multiple integrated circuits. 
       FIG. 93  illustrates one embodiment of a method for relaying a signal indicative of a condition at an end effector  4400 . The method  4400  may comprise generating  4402 , by a sensing module (e.g., the sensing module  4004  described herein), a signal indicative of a condition at an end effector, such as end effector  4002 . The signal may represent any measurable condition at the end effector  4002 , such as, for example, the thickness of tissue clamped in the end effector  4002 . The sensing module may generate the signal using a sensor, such as, for example, the sensor  4116  of the sensing module  4104  shown in  FIG. 90 . The method  4400  may further comprise, transmitting  4404 , by a radio module the generated signal as a low-power signal. For example, the radio module  4124  shown in  FIG. 90  may transmit a low-power signal  4006 . In practice, the transmission power of the radio module may be limited by the size of the antenna and power source that may be disposed in the end effector  4002 . Given the limited space, the transmission power of the radio module may be limited to a low-power signal  4006 . The low-power signal  4006  may be transmitted using the radio module at a power-level that allows the low-power signal  4006  to be received by a relay station  4008  in the handle  4020  of the surgical instrument  4010 . 
     The method for relaying the signal indicative of a condition at an end effector  4400  may further comprise receiving  4406  the low-power signal by a relay station, such as, for example, relay station  4008 . After receiving the low-power signal, the relay station may convert  4408  the low-power signal to a high-power signal, such as, for example, the high-power signal  4012 . The conversion of low-power signal to high-power signal may comprise amplification of the low-power signal by an amplification module, such as the amplification module  4230  shown in  FIG. 91 . Conversion of the low-power signal to high-power signal may also comprise converting the communication standard of the low-power signal to a communication standard suitable for transmission of the high-power signal. For example, the method  4400  may comprise converting  4408 , using a processing module, the received low-power signal from a first frequency to a second frequency. 
     After converting  4408  the low-power signal to the high-power signal, the method  4400  may further comprise transmitting  4410 , by the relay station, the high-power signal to a remote location, such as, for example, an operating room viewing screen or a hospital network. The high-power signal may be received  4412  by the viewing screen, which may display a graphical representation of the condition at the end effector to a user. In some arrangements, the method may comprise, selecting, by a user, a frequency and/or a communication protocol for the high-power signal prior to the conversion of the low-power signal. The frequency and the communication protocol may be selected from a plurality of frequencies stored in a memory module of the relay station. 
     Electromechanical Soft Stop 
     In various forms, the surgical instrument may employ a mechanical stop adapted to stop or decelerate a motor driven element at or near an end of a drive stroke. According to various forms, the mechanical stop may comprises a hard stop structured to abruptly terminate movement of the motor driven element and/or a soft stop structured to decelerate the motor driven element at or near an end of stroke. As described in more detail below, in certain forms, such instruments may include an electromechanical stop comprising the mechanical stop and a control system configured to measure and/or monitor current provided to a motor used to drive the motor driven element. In one form, the control system is configured to terminate power to the motor or otherwise disengage the drive motion of the motor driven element upon determining the occurrence of a current meeting predetermined parameters. 
     It is to be appreciated that for brevity and ease of understanding the various aspects of the mechanical and electromechanical stops described herein are generally described with respect to surgical instruments and associated drive members comprising cutting and fastening devices. However, those having skill in the art will appreciate that the present disclosure is not so limited and that the various mechanical stops and related electromechanical features disclosed herein may find use in a variety of other devices known to the art. For example, while additional uses will become more apparent below, various mechanical stops disclosed herein may be employed in any device comprising an electrically controlled motor and/or control or drive system, for example, as well as non-endoscopic surgical instruments, such as laparoscopic instruments. Referring again to  FIGS. 1-6 , which illustrate an electromechanical surgical instrument  10  equipped with on form of a mechanical stop according to one aspect. The handle assembly  20  is operatively coupled to the elongate shaft assembly  30 , a distal portion of which is operatively attached to the end effector  102 . The end effector  102  comprises a proximal end  103  and a distal end  104 . As described above, the elongate channel member  110  may be configured to operably and removably support the staple cartridge  130 , and the anvil assembly  190  may be selectively movable relative to the staple cartridge  130  between an open position (see  FIG. 4 ) and an open position (see  FIG. 6 ) to capture tissue therebetween. 
     In certain forms, the instrument  10  comprises a drive member, which may be any portion or component of the instrument  10  that is movable by action of a motor. In various forms, the drive member may include the elongate shaft assembly  30 , the end effector  102 , or one or more portions or components thereof, such as the sled  170  or tissue cutting member  160 , the body portion  162  of which may be threadably journaled on the end effector drive screw  180  such that it is rotatably mounted within the elongate channel  110 . As described above, the sled  170  may be supported for axial travel relative to the end effector drive screw  180  and may be configured to interface with the body portion  162  of the tissue cutting member  160 . The end effector drive screw  180  may be rotatably supported within the elongate channel  110  as described above. Rotation of the end effector drive screw  180  in a first direction causes the tissue cutting member  160  to move in the distal direction through a drive stroke. As the tissue cutting member  160  is driven distally through the drive stroke, the sled  170  is driven distally by the tissue cutting member  160 . In various forms, the staple cartridge  130  may be fitted with a mechanical stop comprising a soft stop. According to one aspect, the soft stop comprises one or more bumpers  174  to cushion the sled  170  as it reaches its end of stroke near the distal-most position within the elongate channel  110 . The bumpers  174  may each be associated with a resistance member  175 , such a spring  176 , to provide the bumper with a desired amount of cushion. 
     As described in greater detail above, the sled  170  and tissue cutting member  160  are movable through a drive stoke along shaft axis A-A extending between the proximal end  103  of the end effector  102  and the distal end  104  of the end effector  102  to simultaneously cut and fasten tissue. While the illustrated end effector  102  is configured to operate as an endocutter for clamping, severing and stapling tissue, in other aspects, different types of end effectors may be used, such as end effectors for other types of surgical devices, such as graspers, cutters, staplers, clip appliers, access devices, drug/gene therapy devices, ultrasound, RF or laser devices, etc. 
     Referring to  FIG. 94 , which illustrates the distal end  104  of the end effector  102  shown in  FIGS. 1-6 , a drive member  158  comprising the sled  170  and cutting member  160  is movable through a drive stroke defined along the shaft axis A-A between a proximal home position and a distal end of stroke position. In one aspect, the end of stroke position is defined between a first and second position S 1 , S 2  (see  FIGS. 97 and 78 ). In various forms, at least one of the home position and the end of stroke includes a mechanical stop, such as a hard stop or soft stop, which may physically impede, e.g., block or limit, additional longitudinal movement beyond a respective stop position. In one form, both the home position and the end of stroke comprise a mechanical stop. As illustrated, the drive member  158  is distally disposed prior to or adjacent to the end of stroke. 
     As described above, the surgical instrument  10  may employ a control system for controlling one or more motors and related drive components as described above.  FIG. 95  is a diagram depicting one form of a system comprising a control system  1400 , drive motor  1402 , and power source  1404  for use with a surgical instrument employing an electromechanical stop, which may include a mechanical soft or hard stop according to various aspects. The surgical system comprises a power source  1404  operatively coupled to the drive motor  1402  via the control system  1400 . The power source  1404  may be configured to supply electric power to the drive motor  1402  to drive a drive member, such as drive member  158 . In certain aspects, the power source  1404  may comprise any convenient source of power such as a battery, a/c outlet, generator, or the like. The control system  1400  may comprise various modules or circuits and may be operative to control various system components, e.g., the drive member  158 , power source  1404 , or a user interface. The control system  1400  may be configured to control, monitor, or measure various instrument  10  operations, signals, inputs, outputs, or parameters, for example. 
     In various forms, the control system  1400  may be similar to control system  800  described above. For example, in various aspects, the control system  1400  may be configured to “electrically generate” a plurality of control motions. The term “electrically generate” refers to the use of electrical signals to actuate or otherwise control a motor  1402 , for example motors  402 ,  530 ,  560 , and  610 , or other electrically powered device and may be distinguished from control motions that are manually or mechanically generated without the use of electrical current. For example, the control system  1400  may electrically generate a control motion, such as a rotary control motion, comprising delivering power to the drive motor, which may be in response to a user instruction, such as an electrical signal given to the control system via actuation of an actuator, such a drive or firing trigger associated with the handle assembly  20 . In certain aspects, the control system  1400  may electrically generate a rotary control motion comprising termination of power delivery to the drive motor  1402 , which may be in response to a user or biasing mechanism returning the actuator or firing trigger to an open position. In at least one aspect, the control system  1400  may electrically generate a rotary control motion comprising termination or reduction of power delivery to the drive motor  1402  due to a measured electrical parameter reaching a predetermined value. For example, the control system  1400  may terminate power delivery to the drive motor  1402  when measured current reaches a predetermined threshold. 
     Referring generally to  FIG. 1  and  FIGS. 94 and 95 , in various forms, the surgical instrument  10  comprises a handle assembly  20  equipped with a user interface configured to transmit an actuation signal from the user, e.g., a clinician, to the control system  1400  to electrically generate a control motion with respect to the elongate shaft assembly  30 , the end effector  102 , or the drive member  158 . For example, in certain aspects, the user interface comprises a trigger assembly comprising an actuator or trigger operative to provide an input signal to the control system  1400  to control a supply of power to the drive motor  1402 , such as firing motor  530  (see  FIG. 23 ). The assembly may comprise a closure trigger for closing and/or locking the anvil assembly  190  and a firing trigger for actuating the end effector  102 , e.g., driving the drive member  158  through the drive stroke. In operation, the closure trigger may be actuated first, thereby bringing the anvil assembly  190  to the closed position, e.g., capturing tissue between the staple cartridge  130  and the anvil assembly  190 . Once the clinician is satisfied with the positioning of the end effector  102 , the clinician may draw back the closure trigger to its fully closed, locked position. The firing trigger may then be actuated from an open position to a closed position to actuate the drive member  158  through the drive stroke. In various aspects, the firing trigger may return to the open position when the clinician removes pressure or may be mechanically resettable to the open position via operative connection to the actuation of the drive member  158  or a separate mechanism. In one aspect, the firing trigger may be a multi-position trigger whereby once the drive member  158  has reached a position at or near the end of stroke, the firing trigger may be actuated from a second open position to a second closed position to actuate the drive member  158  proximally toward the home position. In some such aspects, the first and second open and closed positions may be substantially the same. Depending on the desired configuration, in certain aspects, a release button or latch may be configured to release the closure trigger from the locked position. As explained in more detail below, following actuation of the firing trigger from the open position to the closed position, the firing trigger may be operatively disengaged, e.g., actuation of the firing trigger may provide an initial actuation input signal that may be routed to the control system  1400  to instruct the control system  1400  to initiate actuation of the drive member  158 . In certain configurations, absent a user override feature, actuation of the drive member  158  will terminate at or near the end of stroke by action initiated by the control system, e.g., disengaging or interrupting power delivery to drive motor, even when the firing trigger is in the closed position. 
     In one form, the trigger assembly comprises a joystick control, which may be similar to the joystick control  840  described above. For example, as shown in  FIGS. 33-39 , the joystick control may beneficially enable the user to maximize functional control of various aspects of the surgical instrument  10  through a single interface. In one aspect, the joystick control rod  842  may be operably attached to the joystick switch assembly  850  that is movably housed within the switch housing assembly  844  such that the switch housing assembly  844  is mounted within the pistol grip  26  of the handle assembly  20 . The switch housing assembly  844  may include a biasing member  856  to bias the joystick switch assembly  850  and the joystick control rod  842  in a desired position when not subject to external positioning, for example, by a user. The joystick control  840  may be electrically coupled to the control system  1400  to provide control instructions to the control system  1400 . For example, manipulation of the joy stick control rod  842 , such as depressing or directional movement, may allow the user may control various control movements associated with the surgical instrument  10 , which may include actuation of the drive member  158 . 
     As described above, various forms of the surgical instrument  10  comprise one or more electrically operated or powered motors, such as motors  402 ,  530 ,  560 , and  610 . The one or more motors may, for example, be located in a portion of the handle assembly  20  or elongate shaft assembly  30  of the instrument  10  and be operative to drive the drive member  158  between the home position and the end of stroke. In one form, the motor may include a brushless motor, a cordless motor, a synchronous motor, a stepper motor, or any other suitable electric motor. In certain arrangements, the motor may operate in a rotary or linear actuation mode, e.g., a linear actuator, and may include a transmission coupling between the drive motor  1402  and drive member  158  to convert rotary motion of the drive motor  1402  to linear motion or to couple rotary motion between multiple components. In various forms, a transmission coupling comprising one or more gears or interlocking elements such as belts or pulleys is operative to transmit rotary motion from the drive motor  1400  to one or more segments of the elongate shaft assembly  30  to actuate the end effector  102 . For example, rotation of the end effector drive screw  180  in a first direction causes the drive member  158  to move in a first direction, e.g., a distal direction, along shaft axis A-A. In various aspects, rotation of the end effector drive screw  180  in a second direction, opposite of the first, causes the drive member  158  to move in a second direction, e.g., a proximal direction, along shaft axis A-A. In one aspect, the drive motor  1400  drives the drive member  158  distally toward the end of stroke and is reversible to drive the drive member  158  proximally toward the home position. For example, the drive motor  1402  may be reversible, by, for example, reversing the polarity of the voltage supply, thereby producing reverse rotation or motion of the motor and, hence, reverse movement of the drive member  158 . As such, the drive member  158  may be moved between positions along the drive stroke in both proximal and distal directions by conventional methods, or methods such as those disclosed in U.S. patent application Ser. No. 12/235,782, now U.S. Pat. No. 8,210,411, which is incorporated herein by reference in its entirety. Notably, although the instruments  10  described herein generally refer to handheld instruments comprising a handle, in various forms, instruments  10  comprising mechanical stops, that may operate as part of an electromechanical stop, may be adapted for use in robotic or similar devices used by robotic systems. 
     In certain aspects, the surgical instrument  10  comprises a reversible motor and includes a proximal mechanical stop and a distal mechanical stop. In various aspects, as described above, actuating the firing trigger signals actuation of the drive member  158  through the drive stroke. When the drive member  158  reaches the end of the drive stroke, for example, when a cutting member  160  reaches the distal end of its cutting stroke, an end of stroke or direction switch, for example, may be switched to a closed position, reversing the polarity of the voltage applied to the motor  1402  to thereby reverse the direction of rotation of the motor  1402 . Such a switch may be associated with the control system  1400  and may be in addition to or in the alternative to termination of power delivery to the drive motor  1402 . Notably, however, in other aspects a manual return switch may be provided to reverse the motor  1402  and return the drive member  158  to its original or home position. 
     A mechanical stop is disposed at or near the end of stroke and is structured to increase resistance to movement of the drive member  158  through the end of stroke. The mechanical stop includes a soft stop comprising a pair of bumpers  174  each operatively coupled to a resistance member  175 . The bumpers  174  are configured to contact the drive member  158  at or near the end of stroke. For example, the bumpers  174  shown in  FIG. 94  are structured to contact a contact surface  173  of at least one wedge  172 . In various aspects, the bumpers  174  may be dimensioned to complement a dimension of the contact surface  173 . For example, in at least on aspect, the bumpers  174  may be dimensioned to present an angled surface substantially equivalent to the contact surface  173 . In this way, stability of the contact between the bumpers  174  and the wedges  172  may be increased and the force applied to the contact surface  173  may be distributed along a larger structural area of the wedges  174 . Similarly, in one aspect, the bumpers  174  comprise a flexible, such as an elastic or cushion surface to receive the contact surface  173  and reduce component breakdown. In one form, the resistance members  175  each comprise a spring  176  positioned between a bumper  174  and a hard stop  178  to provide resistance and deceleration of the drive member  158  at or near the end of stroke  158 . 
     It will be appreciated that various aspects of surgical instruments  10  may be fitted with multiple bumpers  174  and resistance members  175  and that bumpers  174  and resistance members  175  may be structured to contact other portions of the drive member  158 . For example, the instrument  10  may comprise an additional stop, which may be in addition to or instead of the above hard stop  178  and/or the soft stop arrangements. Thus, in one form, referring to  FIG. 94 , the drive screw  180  may be fitted with a stop that may include a soft stop comprising a bumper  290  associated with a resistance member  291  positioned along the drive stroke and opposed to a contact surface  292  of the drive member  158 . In one form, the resistance member  291  comprises an elastomeric material that may be compressible between the bumper  292  and a hard stop  294  to absorb the longitudinal force of the drive member  158 . In certain aspects, multiple soft stops may be configured to contact the drive member  158  at different predetermined positions. For example, in one form, the drive member  158  contacts bumper  290  before bumpers  174 , for example, to provide a more identifiable current spike, e.g., to produce a current spike comprising two distinct current spike components, the magnitude and/or temporal separation of which may be used to increase assurance of an occurrence of a current spike. 
     In various forms, resistance members  175  comprise a compressible portion that may or may not be associated with a hard stop  178 . For example, in one aspect a resistance member  175  may be housed between the hard stop  178  and the bumper  174  and may include a compressible portion, such as a spring  176 , elastomeric material, such as a polymer, foam, or gel. In operation, the bumper  174  may be accelerated toward the compressible portion upon contact with the drive member  158  whereby the compressible portion compresses by a given degree. In various aspects, the resistance member  175  may comprise a deceleration portion, such as a brake. In one aspect the deceleration member comprises a compressible cell, such as a hydraulic pneumatic cell through which contact with the drive member  158  may compress a piston positioned within the cell to impart an increase in pressure configured to decelerate or brake the drive member  158 . In certain aspects, the soft stop may be structured to apply a smooth or gradual resistance and/or deceleration with respect to time and/or distance. For example one or more coiled springs having the same or different compressibility properties may be structured or arranged to precisely control deceleration or braking of the deceleration member, e.g., in a gradual or stepped manner. In one form, the soft stop may be structured to apply a progressive resistance to the distal motion of the drive member  158 . 
     In various forms, a soft stop includes a biasing member configured to bias the contact member away from the hard stop. It will be appreciated that, in some aspects, the biasing member may be the same or share similar components with the resistance members  175 . Thus, in some forms, a biasing member may be structured to compress between the bumper  174  and the hard stop  178  by the longitudinal actuation force of the drive member  158  and thereafter return to a precompressed state upon removal of the force. In certain aspects, the biasing member may be actuatable, movable, and/or compressible to counter the actuation motion of the drive member  158 . Notably, compressing or otherwise countering a bias associated with the resistance members  175  may result in an energy transfer that may, at least temporarily, be stored or retained by the soft stop in a potential energy position. In one aspect, the resistance members  175  may be maintained in a potential energy position by a latch, hook, or obstruction, for example, which may prevent one or more resistance members  175  from returning to a precompressed state. Beneficially, the stored energy may be released, for example, by the user and/or the control system  1400  whereby at least a portion of the stored energy is applied to return the drive member  158  to the home position. 
     In various aspects, resistance members  175  may comprise additional configurations. For example, in one aspect, one or more magnets, such as permanent magnets, may be positioned to repel an opposed permanent magnet associated with the drive member  158 . For example, one or more magnets may be rotatable or movable to adjust the size of repulsive magnetic fields opposing longitudinal movement. Various other aspects may employ coil magnets electrically coupled to the control system for activation before or after successful deceleration of the drive member  158 . Additional resistance members  175  may comprise reciprocating structures including arrangements implementing pulleys and/or gears, for example. 
     In various aspects, a mechanical stop comprising a soft stop may or may not be associated with a hard stop  178 . For example, in some forms the soft stop includes a hard stop  178 , while in other forms the soft stop does not include a hard stop or the hard stop  178  may operate as an auxiliary stop. In some forms, the soft stop may comprise a spring loaded hard stop  178  to provide a gradual and/or progressive resistance to the drive stroke or deceleration of the drive member  158 . For example, the soft stop may be configured to gradually decrease the velocity of the drive member  158  by providing resistance to the proximal or distal force applied to the drive member  158  by the drive motor  1402  or present in the inertia of the system. In at least one form, the magnitude of resistance provided by the soft stop to counter or decelerate the actuation or drive motion may be selectively adjustable. For example, the instrument  10  may be fitted with one or more soft stops that may be selectively slid or rotated to multiple positions along the drive stroke. As such, a user may customize the position of a soft stop for a particular application. In one form, an electrochemical device comprising a soft stop may include an adjustable dial to adjust the resistance provided by the soft stop along the end of stroke. In some such forms, adjusting the dial may simultaneously adjust the longitudinal distance encompassed by the soft stop and, hence, the end of stoke, as well as threshold values associated with determining a current spike, as explained in more detail below. In one form, a warning signal may be provided to the user when a manual setting is set beyond a predetermined mechanical tolerance. 
     Referring again to  FIG. 95 , in various forms, the control system  1400  is configured to formulate and/or respond to feedback information that may, at least in part, be derived from information measured by the control system  1400  or obtained from other system components. For example, in one aspect, the control system  1400  may be configured to initiate power delivery to system components in response to an input signal, such as an instruction provided by a user. In certain aspects, the control system  1400  may generate or provide information, such as a warning or instrument state, to a user via the user interface, such as a visual or audio display. Signals or inputs generated by the control system  1400  may be, for example, in response to other signals or inputs provided by a user, instrument components, or may be a function of one or more measurements associated with the instrument  10 . In certain aspects, the control system  1400  may be configured to monitor or receive various measurements and thereafter interpret, calculate, and/or decode the information and respond in a predetermined way. 
     In one aspect, the control system  1400  includes or may be selectively associated with a semiconductor, computer chip, or memory. As stated above, inputs provided to or from the control system  1400 , such as those supplied by the user or produced by the control system  1400  in response to instructions, signals, or measured parameters may be analog or digital. Accordingly, in some forms, the control system  1400  may be configured to send or receive analog or digital inputs or signals to or from instrument components. In various aspects, the control system  1400  may use software that may employ one or more algorithms to further formulate input signals to control and monitor instrument components. Such formulated input signals may be a function of criteria measured and/or calculated by the control system  1400  or, in some instances, provided to the control system  1400  by another instrument component, a user, or a separate system in operative communication with the control system  1400 . For example, the control system  1400  may respond by activating or deactivating the drive motor  1402 , terminating, initiating power to the drive motor  1402  or to additional system components, or by providing instructions or additional inputs for these or other operations. In various aspects, the control system  1400  may comprise circuitry, for example transistors or switches, configured to monitor electrical parameters associated with the operation of the instrument  10 . For example, control system circuitry may be configured to activate or deactivate the drive motor  1402  or open or close a power delivery path to the drive motor  1402  when electrical parameters associated with operation of the instrument  10  reach a threshold value, e.g., a current spike, as determined by the circuitry configuration. 
     In certain forms, surgical instruments  10  and systems employing a mechanical stop may operate in an open loop. For example, in one form, the instruments may operate without assistance from a position feedback device configured to provide the control system  1400  with information regarding how the instrument  10  is responding to inputs, such that the control system  1400  may modify output. In various aspects, as introduced above, the control system  1400  may monitor power delivery to a drive motor  1402  to determine end of stroke position of the drive member  158 . That is, for example, the control system  1400  through various voltage monitory techniques from which current, namely current spikes, may be determined, may, at least in part, be ascertained using a mechanical stop. For example, a control system  1400  may monitor voltage to determine current with respect to power delivery to a drive motor  1402  and, hence, the drive member  158 , as described above. Resistance to the drive stroke increases torque on the drive motor  1402  resulting in detectable current spikes with respect to the power delivered to the drive motor  1402 . Thus, a large current spike may be measured by the control system  1400  when the drive member  158  contacts a mechanical stop at which time the control system  1400  may respond by terminating power delivery to the drive motor  1402 . Hence, the mechanical stop provides the physical force to decelerate the drive member  158  and produce the current spike that may be ascertained by the control system  1400  to initiate disengagement of the drive motor  1400 . 
     As introduced above, in certain aspects, the control system  1400  is configured to control various operations of the instrument  10 . For example, in certain aspects, the control system  1400  comprises a control circuit  1406  operatively coupled to a drive circuit  1408 . The drive circuit  1408  may be configured to deliver power from the power source  1404  to the drive motor  1402  to drive the drive member  158 . The control circuit  1406  may be configured to control the delivery of power to the drive circuit  1408 . Hence, the control circuit  1406  may be configured to control the drive motor  1402  via control over power delivery to the drive circuit  1408 . The control circuit  1406  may be further configured to monitor, e.g., sample or measure, the power delivered to the drive motor  1402 . For example, the control circuit  1406  may sample input/output voltage and/or current at one or more points of the drive circuit  1408  through which the drive motor  1402  receives power to actuate the drive member  158 . In various aspects, the control circuit  1406  may include or be coupled to the drive circuit  1408  through which it may monitor input/output voltage, for example across a resistor coupled to a current path associated with the drive circuit  1408 , for example. As those skilled in the art will appreciate, the above description is just one manner of measuring and/or monitoring current supplied to the drive motor  1402  and will further recognize that current may similarly be measured and/or monitored by alternate methods known in the art, and, therefore, such methods are within the scope of the present disclosure. In some forms, when the control circuit  1406  detects a spike in the current supplied to the drive motor  1402 , the control system  1400  terminates energy delivery to the drive motor  1402  through the drive circuit  1408 . In various aspects, the control system  1400  may also disengage operative coupling, e.g., transmission, between the drive motor  1402  and the drive member  158 , at least momentarily, in response to a measured current spike. 
     In certain configurations, when electromechanical stops comprise a hard stop designed to abruptly terminate the drive stroke, the instrument  10  may be susceptible to mechanical failure due to, for example, time lag between detection of the current spike and subsequent relief from the actuation force provided by the drive motor  1402 . Additionally, due to the inertia of the system, for example, the drive member  158  may also continue to be actuated or driven after reaching the end of stroke, despite termination of power delivery to the drive motor  1402 . In some instances, the delay in relieving the drive member  158  of the actuation force may drive the drive member  158 , drive motor  1402 , drive screw  180 , or other transmission coupling to mechanical failure. 
       FIG. 96  is a graphical illustration depicting current over time of an instrument  10  employing a electromechanical stop comprising a hard stop  178  without a soft stop. The current between time A, corresponding to a position of the drive member  158  proximal to the end of stroke, and time B, corresponding to a position of the drive member  158  upon contact with the hard stop  178  at an end of stroke, is relatively low or steady. However, at time B, the current spikes, representing contact between the drive member  158  and the hard stop that is positioned at the end of stroke. Due to a time lag between detection of the current spike sometime after time B and termination of power delivery to the drive motor  1402 , the drive motor  1402  continues to drive the drive member  158 , although unsuccessfully, against the hard stop  178  until time C, when power delivery to the drive member  158  is terminated. Although not shown, the inertia of the system may also continue to actuate the drive member  158  against the hard stop  178  for a period of time after time C. 
     As stated above, while providing the convenience of open loop operation, surgical instruments operating as depicted in  FIG. 76  may be susceptible to mechanical failure due to, for example, the time lag between detection of the current spike and subsequent relief from the actuation motion. According to various forms, referring to  FIGS. 97 and 98 , the instruments  10  disclosed herein may comprise electromechanical stops comprising a soft stop structure to contact and decelerate the drive member  158  prior to reaching the end of stroke to induce an identifiable current spike, thereby increasing the amount of time the control system  1400  has to detect and respond to the current spike. The surgical instrument  10  includes various features similar to those illustrated in  FIGS. 1 and 70 ; thus, like features are identified using like numeric identifiers and, for brevity, will not be described again. The instrument  10  includes an electromechanical stop comprising a soft stop to oppose movement of a drive member  158  at or near the end of the drive stroke or segment thereof, such as at a proximal home position or a distal end of stroke extending between a first soft stop position S 1  and a second soft stop position S 2  along the shaft axis A-A. The electromechanical stop further comprises a hard stop  178  disposed at position H. The soft stop comprises a bumper  174  and a resistance member  175  disposed at or near the end of stroke, e.g., at least partially within the first soft stop position S 1  and second soft stop position S 2 . The bumper  174  and resistance member  175  function to provide resistance to the drive member  158  within the end of stroke defined between the first soft stop position S 1  and second soft stop position S 2 . In various forms, the bumper  174  and resistance member  175  may also function to decelerate the drive member  158  from the first soft stop position S 1  to the second soft stop position S 2 . In certain forms, a soft stop may be positioned in any preferred location where it is desirable to provide resistance to or begin decelerating the drive member  158 . 
       FIG. 97  depicts the drive member  158  in the process of extending through the drive stroke at a position proximal to the first soft stop position S 1 .  FIG. 98  depicts the drive member  158  after fully extending through the drive stroke beyond the first soft stop position S 1  of the end of stroke such that it is positioned at a second soft stop position S 2  of the end of stroke. Accordingly, the soft stop is positioned to contact the drive member  158  at the first soft stop position S 1  and thereafter compress distally toward the second soft stop position Sz due to compressive interaction with the hard stop at position H. Accordingly, the second soft stop position S 2  may effectively comprise a hard stop position H* with respect to the drive member and the extreme distal terminus of the end of stroke. In various aspects, the drive member  158  may completely or appreciably decelerate prior to reaching the hard stop position H* at the second soft stop position S 2 . Thus, in such aspects, a hard stop, if present, may comprise a redundant or safety feature. 
     Resistance to the actuation motion provided by the mechanical stop, which may be accompanied by a decelerating or braking force, may be gradual, progressive, or stepped with respect to distance and/or time, for example. That is, in some aspects, a soft stop presents a path of increased resistance between a first soft stop position S 1  and the second soft stop position S 2 . Notably, the end of stroke does not necessarily imply that the functional operation of the drive member continues throughout the entire end of stroke, e.g., to the second soft stop position S 2 . For example, in one form, the end of stroke is positioned at or slightly proximal to the distal most staple. In another form, the position of initial contact with the soft stop, e.g., at the first soft stop position S 1 , is distal to the distal most staple. That is, the drive member  158  may not contact or experience significant resistance to longitudinal movement through the drive stroke until the distal most staple has been ejected, at which time increased resistance and/or deceleration may take place. In this way, movement of the drive member will not be prematurely limited by action of the control system  1400 . 
       FIG. 75  is a graphical illustration depicting current over time of an instrument  10  employing an electromechanical stop comprising a soft stop according to various aspects. The current between time A*, corresponding to a position of the drive member  158  proximal to the end of stroke, and time B* 0 , corresponding to a position of the drive member  158  upon contact with the soft stop, for example at a bumper  174 , the current is relatively low or steady. However, following time B* 0  the current gradually begins to spike representing increasing resistance to the longitudinal motion of the drive member. In various aspects, the gradual increase in resistance may advantageously increase the time in which the current spike occurs, for example between times B* 0  and B* 2 , effectively slowing down response time to give the control system  1400  time to react, thus minimizing the adverse effects of the time lag explained above with respect to  FIG. 96 . In certain aspects, the control system  1400  may monitor voltage and measure current supplied to the drive motor  1402 , as described above. The control system  1400  may be configured to respond in a predetermined way to changes in current. For example, upon reaching a threshold current, for example at time B* 1 , the control system  1400  may terminate power supply to the drive motor  1402 . In one configuration, the threshold current may comprise a time component. For example, the threshold current may include a current differential over a specific period of time. In certain configurations, a current spike may comprise one of multiple predetermined current thresholds, each defined by a ratio of a current differential over a time period. As can be seen in  FIG. 99 , the gradual increase in resistance may also advantageously reduce impact loading on the end effector  102  upon contact with a hard stop at time B* 2  as well as reduce the time period B* 2  to C* in which the drive motor  1402  continues to actuate the drive member  158  against the hard stop  178  after distal movement has ceased. 
     In certain aspects, the control system  1400  may determine that a predetermined current threshold as measured by an increase or slope of current over time, for example, has been achieved and may thereafter terminate a power input signal provided to drive motor  1402 . For example, in one configuration, the control system  1400  may monitor current and thereby terminate power delivery to the drive motor  1402  when a magnitude of the current increases a predetermined amount over a given period of time. In various aspects, these or other values, such as threshold values, may be adjusted by a user such as manually or by accessing onboard protocol via an administrative link, such a through a computer. In at least one configuration, the drive circuit  1408  or control circuit  1406  comprises a variable resister such that a user may vary the current supplied to the drive motor  1402  by varying the extent of actuation with respect to the trigger. For example, the rotation of the firing motor  530  may be proportional to the pressure or movement a user applies to the actuator or trigger. In one form the control circuit  1406  may communicate with the drive circuit  1408  such that threshold values may be raised or desensitized. 
     In certain configurations, a plurality of sensors or electrical components may be employed in the end effector  102  to provide various forms of feedback to the user. In one aspect, sensors may provide feedback to the control system  1400  to automatically control the various motors associated with the instrument. For example, in one aspect the surgical instrument comprises multiple motors, such as motors  402 ,  530 ,  560 , and/or  610 , that are actuatable by one or more control systems, such as control systems  800  and  1400 , to electrically generate control motions. The control systems may be configured to operatively control the motors and receive positional feedback from a plurality of sensors configured to monitor positional information. In certain aspects, the control systems may use the positional information to electrical generate altered or modulated control motions via control of power delivery to one or more motors or may provide various positional information to the user, for example. In various aspects, the control systems may be operable in a hybrid open/closed loop system. For example, the control system  1400  may be configured to operate the drive motor  1402 , such as firing motor  530  in an open loop as described herein while also operating various other motors, such as shaft rotation motor  610 , for example, in a closed loop. In one aspect, the control system  1400  may be configured such that the user may selectively choose which motors the control system  1400  may operate in a closed or open loop to, for example, customize the various operations of the instrument  10  as may be desired. 
     It will be appreciated that one or more inputs may be provided by a user which may or may not be subject to evaluation by the control system  1400 . For example, the control system  1400  may include an override mode in which one or more inputs provided to the control system  1400  by one or more users or other control systems in communication with the control system  1400  may be forwarded and/or provided to the instrument  10 . For example, when the drive member  158  is in the home position, the control system  1400  may lockout, prevent, or ignore instructions to couple delivery of power to the drive motor  1402  or otherwise engage the drive motor  1402  to electrically generate the actuation motion of the drive member  158 . In at least one aspect, lockout occurs or is the default state or condition of the system until the occurrence of one or more events, such as closure of the anvil  190  or adequate mechanical or electrical feedback, such as, for example, latching of components, user initiated override, change in measured parameter at, near, or along the path or drive member. 
     In various aspects, one or more mechanical stops including soft stop assemblies according to the present disclosure may be provided in a kit. The kit may have specific application to one or more select devices or may be universal or modifiable for universal application to a number of devices. For example, a soft stop assembly kit may contain a replacement deceleration member, such as resistance members and/or contact members, such as bumpers. In one form, a kit includes replacement or aftermarket bushings that may be used as or be insertable within a housing dimensioned to support a resistance member in order to increase the resistance provided by the soft stop at one or more locations along the drive stroke. In various forms, shims may be provided to adjust clearance between a stop and the body of the device. In some aspects, the contact member may include a permanent or temporary, such as replaceable, modifiable, or upgradable, contact guard structured to be disposed between the drive member and the bumper, the resistance member, and/or the hard stop. The contact guard may be formed from an elastic or other material that is at least partially compressible when contacted by the accelerated mass of the drive member or impacted upon the soft or hard stop. One aspect of a guard may be a polymer that may slip, slide, snap, or be molded onto a portion, such as a contact surface of the drive member  158 . In another aspect, a guard may be fitted or fittable onto a face of the bumper  174 . In yet other aspects, the bumper  174  may comprise a contact configured to contact and at least partially absorb the force of the accelerated mass of the drive member  158  to prevent or partially limit the extent of physical damage or mechanical failure to the drive member  158 , drive motor  1402 , drive screw  180 , or associated components. 
     In some forms, removing a surgical instrument, such as the surgical instrument  10  shown in  FIGS. 1 and 2 , from a patient may be difficult, as the end effector  102  may be in an articulated or rotated position, preventing the end effector  102  from passing through a trocar or other access point into a patient. A clinician may be unaware of the current articulation state of the end effector  102 , such as, for example, articulated along the articulation axis  1343 , and may attempt to remove the surgical instrument  10  without first straightening the end effector  102 . In various forms, a surgical instrument be configured such that its end effector is straightened based on input from a sensor (e.g., the instrument may have a sensor-straightened end effector). In this way, the clinician may ensure that end effector  102  is straight with respect to the articulation axis B-B prior to removing the end effector  102  from a patient, such as, for example, through a trocar. In various forms, a sensor may be configured to trigger a powered straightening event as the end effector is removed from the patient. 
       FIG. 105  illustrates one form of a surgical instrument  5810  comprising a sensor-straightened end effector  5802 . A sensor  5826   a ,  5826   b  may detect a gross proximal motion of the surgical instrument  5810 . The gross proximal motion may indicate that the surgical instrument  5810  is being removed from the patient, such as through a trocar or an overtube. A minimum threshold proximal motion may be set to prevent the end effector  5802  from straightening due to a slight proximal adjustment of the surgical instrument  5810  during treatment. In various forms, when the gross proximal motion of the surgical instrument  5810  exceeds a minimum threshold, the sensor  5826   a ,  5826   b  may send a signal to a motor, such as, for example, the articulation control motor  402 , to cause the motor to straighten the end effector  5802 . 
     In some forms, the sensor  5826   a ,  5826   b  may be located in the shaft  5831 , the end effector  5802 , the handle  5820 , or any other suitable location to detect a gross proximal movement of the surgical instrument  5810 . In various forms, the sensor  5826   a ,  5826   b  may comprise any suitable sensor for detecting movement of the surgical instrument  5810 . For example, the sensor  5826   a ,  5826   b  may comprise a sensor configured to measure acceleration, such as an accelerometer. When the accelerometer detects acceleration in a proximal direction above a predetermined threshold, the accelerometer may send a signal to the articulation control motor  402  to activate a straightening process. As another example, the sensor  5826   a ,  5826   b  may comprise a proximity sensor, such as a magnetic sensor, a Hall Effect sensor, a reed switch sensor, or any other suitable proximity sensor. In various forms, the proximity sensor may be configured to measure the proximity of the sensor  5826   a ,  5826   b  to a fixed point, such as a trocar  5858  or an overtube  5960 . As the surgical instrument  5810  is withdrawn in a proximal direction, the proximity between the sensor  5826   a ,  5826   b  and the fixed point may decrease, causing the sensor  5826   a .  5826   b  to send a signal to the articulation control motor  402  to activate a powered straightening process of the end effector  5802 . In various forms, multiple sensors may be included to provide a redundant check for the straightening process. 
     In one form, a first sensor  5826   a  and a second sensor  5826   b  may be disposed on the surgical instrument  5810 . The first sensor  5826   a  may be located on a proximal portion of the shaft  5831  and the second sensor  5826   b  may be located on a distal portion of the shaft  5831 . Those skilled in the art will recognize that the first and second sensors  5826   a ,  5826   b  may be located in any suitable portion of the surgical instrument  5810  such as, for example, the handle  5820 , a detachable surgical module, the shaft  5831 , or the sensor-straightened end effector  5802 . In some forms, the first sensor  5826   a  may comprise an accelerometer configured to detect a gross proximal movement of the surgical instrument  5810 . In some forms, the second sensor  5826   b  may comprise a proximity sensor configured to detect a distance between the second sensor  5826   b  and a fixed point, such as, for example, the trocar  5858 . In the illustrated form, the trocar  5858  comprises a plurality of magnets  5822 . The plurality of magnets  5822  may generate a constant magnetic field. The second sensor  5826   b  may be configured to detect an increase in intensity of the magnetic field, indicating movement of the second sensor  5826   b , and therefore the sensor-straightened end effector  5802 , towards the trocar  5858 . 
     In one form, the first sensor  5826   a  and the second sensor  5826   b  may be configured to activate a powered straightening process of the sensor-straightened end effector  5802 . In operation, the first sensor  5826   a  may detect a gross proximal movement of the surgical instrument  5810  by detecting a proximal acceleration above a predetermined threshold. The first sensor  5826   a  may send a first signal to the articulation control motor  402  to activate the powered straightening process. In some forms, the second sensor  5826   h  may also detect the gross proximal movement of the end effector by detecting a change in the magnetic field intensity between the sensor  5826   b  and a fixed point, such as the trocar  5858 . The second sensor  5826   b  may send a second signal to the articulation control motor  402  to activate the powered straightening process. 
     As shown in  FIG. 105 , the sensor-straightened end effector  5802  has been articulated at the articulation axis B-B (shown in  FIG. 1 ). The sensor-straightened end effector  5802  may be coupled to a shaft  5831 . An operator may move the surgical instrument  5810  in a proximal direction, causing the shaft  5831  and the sensor-straightened end effector  5802  to move in a proximal direction. The proximal movement may be detected by a first sensor  5826   a . The first sensor  5826   a  may comprise an accelerometer. The first sensor  5826   a  may send a signal to an articulation control motor, such as, for example, the articulation control motor  402  to activate a powered straightening process. The proximal movement may also be detected by a second sensor  5826   b . The second sensor  5826   b  may comprise a magnetic proximity sensor, such as, for example, a Hall Effect sensor or a reed switch sensor. The second sensor  5826   b  may send a signal to the articulation control motor  402  to activate the powered straightening process. The second sensor  5826   b  may send the signal to the articulation control motor  402  independent of the first sensor  5826   a.    
     As the clinician removes the surgical instrument  5810  from the trocar  5858 , the powered straightening process straightens the sensor-straightened end effector  5802 . After the powered straightening process has completed, the sensor-straightened end effector  5802  is in a straight configuration, as shown in  FIG. 106 . The straightened sensor-straightened end effector  5802  may be withdrawn through the trocar  5858  without damaging the patient or the trocar  5858  and without the clinician needing to manually straighten the sensor-straightened end effector  5802 . In some forms, the surgical instrument  5810  may provide a feedback signal to the user to indicate the activation or progress of a powered straightening process. For example, in some forms, a light-emitting diode (LED) may be located on the handle  5820 . The LED may be illuminated during the powered straightening process to provide the user with a visual indication that the powered straightening process is occurring. 
     In some forms, the first and second sensors  5826   a ,  5826   b  may function as redundant checks on the straightening process. For example, in some forms, both the first and second sensors  5826   a ,  5826   b  may provide a signal to the articulation control motor  402  to activate the straightening process. A signal from either the first sensor  5826   a  or the second sensor  5826   b  may cause the articulation control motor  402  to straighten the sensor-straightened end effector  5802 . In some forms, the powered straightening process may not execute until a signal has been received from both the first sensor  5826   a  and the second sensor  5826   b . In some forms, either the first sensor  5826   a  or the second sensor  5826   b  may independently activate the powered straightening process but the process may be aborted if a signal is not received from both the first and second sensors  5826   a ,  5826   b  within a predetermined time limit. For example, the powered straightening process may be initiated by a signal from the first sensor  5826   a . If a signal is not received from the second sensor  5826   b  within a predetermined time limit, the powered straightening process may be aborted by the surgical instrument  5810 . 
     In some forms, the surgical instrument  5810  may comprise a stop sensor. The stop sensor may detect contact between the sensor-straightened end effector  5802  and a tissue section during the straightening process. If the stop sensor detects contact between the sensor-straightened end effector  5802  and a tissue section, the stop sensor may send a signal to the articulation control motor  402  to deactivate the straightening process to prevent damage to the patient. In some forms, when the stop sensor determines that the sensor-straightened end effector  5802  is no longer in contact with a tissue portion, the stop sensor may send a signal to the articulation control motor  402  to continue the straightening process. In some forms, the stop sensor may send a signal to the operator, for example through a feedback device, to notify the user that the sensor-straightened end effector  5802  has contacted a tissue section and that the straightening process has been deactivated. The stop sensor may comprise, for example, a pressure sensor disposed on the sensor-straightened end effector  5802 . 
       FIGS. 107 and 108  illustrate one form of a sensor-straightened end effector  5902 , In some forms, the sensor-straightened end effector  5902  may be inserted into a patient through an overtube  5960 . The overtube  5960  may comprise a magnetic ring  5922  located on the distal end of the overtube  5960 . A first sensor  5926   a  and a second sensor  5926   b  may be configured to detect movement of the sensor-straightened end effector  5902  when the shaft  5931  is withdrawn from the overtube  5960 . In some forms, the first sensor  5926   a  may comprise an accelerometer and the second sensor  5926   b  may comprise a magnetic proximity sensor. The second sensor  5926   b  may detect a change in a magnetic field strength as the second sensor  5926   b  is moved in a proximal direction towards the magnetic ring  5922 . As the second sensor  5926   b  approaches the magnetic ring  5922 , the second sensor  5926   b  may generate a signal to initiate a powered straightening process of the end effector  5902 . The second sensor  5926   b  may comprise any suitable sensor for sensing a changing magnetic field, such as, for example, a reed switch sensor or a Hall Effect sensor. As discussed above, the first sensor  5926   a  and the second sensor  5926   b  may provide a redundant check for the powered straightening process. Those skilled in the art will recognize that in some forms, only the first sensor  5926   a  or the second sensor  5926   b  may be included. In some forms, additional sensors may be included to detect a gross proximal movement of the surgical instrument  5910 . 
       FIGS. 109 and 110  illustrate one form of a sensor-straightened end effector  6002  transitioning from an articulated state to a straightened state during removal from a trocar  6058 . In  FIG. 109 , the sensor-straightened end effector  6002  is in an articulated position with respect to the shaft  6031 . A clinician may begin to withdraw the sensor-straightened end effector  6002  through the trocar  6058  in a proximal direction, as indicated by arrow ‘A.’ The proximal movement may be detected by a first sensor  6026   a , a second sensor  6026   b , or both the first and second sensors  6026   a ,  6026   b . The first sensor  6026   a  may comprise an accelerometer configured to detect a gross proximal movement of the shaft  6031 . The second sensor  6026   b  may comprise a magnetic sensor configured to detect a change in a magnetic field between the second sensor  6026   b  and a fixed point, such as, for example, the trocar  6058 . The trocar  6058  may comprise a magnet  6022  to generate a magnetic field. As the shaft  6031  is withdrawn through the trocar  6058 , the strength of the magnetic field detected by the magnetic sensor  6026   b  will change proportionally to the distance between the magnetic sensor  6026   b  and the magnet  6022 . The first sensor  6026   a  or the second sensor  6026   b  may generate a signal to the articulation control motor  402  to activate a powered straightening process to straighten the sensor-straightened end effector  6002  with respect to the shaft  6831 . 
     After the powered straightening process has completed, the sensor-straightened end effector  6002  is in a straight state as shown in  FIG. 110 . In the straight state, the sensor-straightened end effector  6002  may be withdrawn through the trocar  6058  without damaging the patient, the trocar  6058 , and without the clinician needing to manually straighten the end effector  6002 . In some forms, a clinician may be able to override the powered straightening process and maintain the sensor-straightened end effector  6002  in an articulated state during removal from the trocar  6058 . 
       FIG. 111  illustrates one form of a magnetic ring  6121  that may be attached to a trocar  5858 ,  6058  or an overtube  5960 . The magnetic ring  6121  may comprise a plurality of magnets  6122  that may generate a magnetic field. The magnetic field may be detected by a magnetic sensor disposed on a surgical instrument, such as, for example, the second sensor  6026   b . The magnetic sensor  6026   b  may be configured to maintain a sensor-straightened end effector, such as end effector  6002 , in a straightened state when the magnetic sensor detects the magnetic field generated by the magnetic ring  6121 . For example, in one form, the magnetic sensor  6026   b  may be configured to generate a lockout signal that prevents articulation of an end effector if the magnetic sensor  6026   b  detects a magnetic field above a predetermined threshold. The predetermined threshold may be determined based on the strength of the magnetic field generated by the magnetic ring  6121  at a specific distance corresponding to the articulation axis being located outside of the trocar  5858  or the overtube  5960 . In some forms, the magnetic sensor  6026   b  may activate a powered straightening process when the detected magnetic field strength exceeds the predetermined threshold and may generate a lockout signal to prevent articulation of the sensor-straightened end effector  6002  until the detected magnetic field strength drops below the predetermined threshold. 
       FIGS. 112 and 113  illustrate one form of a magnetic sensor  6226  comprising a reed switch sensor. A reed switch may comprise an electrical switch  6250  operated by an applied magnetic field. A pair of contacts may be disposed on ferrous metal reeds in a hermetically sealed glass envelope. The contacts may be normally open, closing when a magnetic field is present, or normally closed and opening when a magnetic field is applied. 
     With reference now to  FIGS. 105 and 106 , a method for controlling a sensor straightened end effector is disclosed. Although the method for controlling a sensor straightened end effector is described herein with reference to  FIGS. 105 and 106 , those skilled in the art will recognize that the method may be used with any of the forms of the sensor-straightened end effector disclosed herein, such as, for example, the forms illustrated in  FIGS. 107-113 . In one form, the method may comprise detecting, by a first sensor  5826   a , a gross proximal movement of a surgical instrument  5810 . The surgical instrument  5810  may comprise a sensor-straightened end effector  5802 . A clinician may articulate the sensor-straightened end effector  5802  during treatment. Once the treatment is complete, the clinician may begin to withdraw the surgical instrument  5810  from the patient, moving the surgical instrument  5810  in a proximal direction. The proximal movement of the surgical instrument  5810  may be detected by the first sensor  5826   a . In some forms, the first sensor  5826   a  may comprise an accelerometer configured to detect a gross proximal movement of the surgical instrument  5810 . The method may further comprise generating, by the first sensor  5826   a , a signal indicating that a gross proximal movement has been detected. The signal may be transmitted by the first sensor  5826   a  to a controller for the articulation control motor  402 , such as, for example, a control circuit such as the control circuit  3702  shown in  FIG. 82 . Additional motor controllers are provided and described with respect to  FIGS. 84, 114-116 , etc. The method may further comprise receiving, by the articulation control motor  402 , the signal from the first sensor  5826   a  and activating, by the articulation control motor  402 , a powered straightening process to straighten the angle of articulation of the sensor-straightened end effector  5802  in response to the received signal. The powered straightening process may return the sensor-straightened end effector  5802  to a zero articulation state. 
     In some forms, the method may further comprise detecting, by a second sensor  5826   b , the gross proximal movement of the surgical instrument  5810 . In some forms, the second sensor  5826   b  may comprise a magnetic proximity sensor, such as, for example, a Hall Effect sensor or a reed switch sensor. The second sensor  5826   b  may be configured to detect the distance between the second sensor  5826   b  and a fixed point, such as a trocar  5858  or an overtube  5960 . The method for controlling a sensor-straightened end effector  5802  may further comprise generating, by the second sensor  5826   b , a signal indicating that the gross proximal movement has been detected. The second signal may be transmitted to the articulation control motor  402 . The method may further comprise receiving, by the articulation control motor  402 , the second signal and activating, by the articulation control motor  402 , the powered straightening process to straighten the angle of articulation of the sensor-straightened end effector  5802 . In some forms, the second sensor  5826   b  may generate the second signal independent of the first sensor  5826   a.    
     In some forms, the first and second sensors  5826   a ,  5826   b  may function as redundant checks on the straightening process. For example, in some forms, both the first and second sensors  5826   a ,  5826   b  may provide a signal to the articulation control motor  402  to activate the straightening process. A signal from either the first sensor  5826   a  or the second sensor  5826   b  may cause the articulation control motor  402  to straighten the sensor-straightened end effector  5802 . In some forms, the powered straightening process may not execute until both a signal has been received from both the first and the second sensors  5826   a ,  5826   b , In some forms, either the first sensor  5826   a  or the second sensor  5826   b  may independently activate the powered straightening process but the process may be aborted if a signal is not received from both the first and second sensors  5826   a ,  5826   b  within a predetermined time limit. For example, the powered straightening process may be initiated by a signal from the first sensor  5826   a . If a signal is not received from the second sensor  5826   b  within a predetermined time limit, the powered straightening process may be aborted by the surgical instrument  5810 . 
     In one form, various surgical instruments may utilize a modular motor control platform. For example, the modular control platform may be implemented by the control circuit  3702 .  FIG. 114  shows one form of a modular motor control platform  6300  comprising a master controller  6306 , one or more motor-controller pairs  6309   a - 6309   c . The platform  6300  may control one or more motors  6318   a ,  6318   b ,  6318   c . The motors  6318   a ,  6318   b ,  6318   c  may be any motors utilized in a surgical instrument. For example, in some forms one or more of the motors  6318   a ,  6318   b ,  6318   c  may correspond to one or more of the articulation motor  402 , the firing motor  530 , the end effector rotation motor  560  and/or the shaft rotation motor  610 . 
     In various forms, the respective controllers  6306 ,  6309   a - 6309   c  may be implemented utilizing one or more processors (e.g., processors implemented on the control circuit  3702 ). The modular motor control platform  6300  may be suitable to control a motor controlled surgical instrument, such as, for example, the surgical instrument  10  illustrated in  FIGS. 1 and 2 . In various forms, the master controller  6306  may be mounted on the distal circuit board  810  or the proximal circuit board  820 . A first motor controller  6314   a  is operatively coupled to a first motor  6318   a  to provide one or more control signals to the first motor  6318   a . A second motor controller  6314   b  may be operatively coupled to the second motor  6318   b  and a third motor controller  6314   c  may be operatively coupled to the third motor  6318   c . The motor controllers  6314   a - 6314   c  are in electrical communication with the master controller  6306 . The master controller  6306  provides control signals to the motor controllers  6314   a - 6314   c  based on a main control process for controlling one or more functions of the end effector  6302 . The main control process may be a predefined process, a user-defined process, or a device generated process. 
     In one form, the main control process may define one or more surgical procedures performable by the surgical instrument  10  comprising one or more functions of the shaft  30  and the end effector  102 . For example, in one form, the main control process may define a cutting and sealing operation of the surgical instrument  10 . The cutting and sealing operation may comprise multiple functions of the surgical instrument  10 , such as, for example, a clamping function, a stapling function, a cutting function, and an unclamping function. A user may indicate the initiation of a cutting and sealing operation in any suitable manner, such as, for example pressing a button or switch on the handle  20 . Those skilled in the art will appreciate that any suitable input method may be used to activate one or more functions of the surgical instrument  10 . 
     In one form, when the clinician indicates initiation of the cutting and sealing operation, such as, for example, by pressing a button on the handle  20 , the master controller  6306  may generate a series of control signals and provide the control signals to one or more motor controllers  6314   a - 6314   c . For example, at time t 0 , a cutting and sealing operation may be initiated. The master controller  6306  may generate a first control signal indicating that a clamping function should be performed. The first control signal may be transmitted to a first motor controller  6314   a  coupled to a first motor  6318   a  configured to control a clamping motion of the end effector  6302 . The first motor controller  6314   a  may, in turn, provide one or more signals to the first motor  6318   a , activating the first motor  6318   a  to pivot the anvil assembly  190  of the end effector  102  to clamp tissue located between the anvil assembly  190  and the cartridge  130 . The master controller  6306  may poll the first motor controller  6314   a  for a status signal until the first motor controller  6314   a  indicates the clamping operation has completed. At time t 1 , the first motor controller  6314   a  may provide a signal to the master controller  6306  indicating the clamping function has completed. 
     At time t 2 , a second control signal may be transmitted from the master controller  6306  indicating that a stapling and cutting operating should be performed. The second control signal may be sent to a second motor controller  6314   b  coupled to a second motor  6318   b . The second motor  6318   b  may be configured to control proximal and distal movement of the cutting portion  164  and/or the sled  170  disposed within the end effector  102 . A stapling and cutting operation control signal may result in the second motor controller  6314   b  activating the second motor  6318   b  to advance the cutting portion  164  and/or the sled  170  in a distal direction causing the staple cartridge  130  to fire and the cutting portion  164  to cut tissue clamped by the anvil assembly  190 , as discussed in more detail above. At time t 3 , the cutting portion  164  reaches a distal-most point and the second motor controller  6314   b  may provide a signal to the master controller  6306  indicating that the stapling and cutting operation has completed. The second motor controller  6314   b  may automatically generate a control signal for the second motor  6318   b  to reverse the direction of the cutting portion  164  until the cutting portion  164  has been fully retracted. 
     After receiving the signal from the second motor controller  6314   b  at time t 3 , the master controller  6306  may provide a third control signal to the first motor controller  6314   a  indicating that a release function should be performed. The first motor controller  6314   a  may generate a control signal for the first motor  6318   a  to cause the first motor  6318   a  to reverse the earlier clamping operation and to unclamp the anvil assembly  190 . The release function may be performed by the first motor controller  6314   a  and first motor  6318   a  simultaneously with the reversing of the second motor  6318   b  to retract the cutting portion  164  to its starting position. The use of a master controller  6306  and individual motor controllers  6314   a ,  6314   b  allows the surgical instrument  10  to perform multiple operations simultaneously without over stressing any of the individual controllers  6306 ,  6314   a ,  6314   b.    
     The motor controllers  6314   a - 6314   c  may comprise one or more independent processes for monitoring and controlling surgical operations, such as, for example, movement of a motor. In some forms, the motor controllers  6314   a - 6314   c  may be configured to operate one or more control feedback loop mechanisms. For example, in some forms, the motor controllers  6314   a - 6314   c  may be configured as closed loop controllers, such as single-input-single-output (SISO) or multiple-input-multiple-output (MIMO) controllers. In some forms, the motor controllers  6314   a - 6314   c  may operate as proportional-integral-derivative (PID) controllers. A PID controller may operate a control loop using three tuning terms, a proportional gain term, an integral gain term, and a derivative gain term. A PID controller may comprise a control process configured to measure a specified variable and compare the measured value of the specified variable to an expected value or set-point of the specified variable. The PID controller may adjust a control variable based on the difference between the measured valued and the expected value of the specified variable. In some forms, the motor controllers  6314   a - 6314   c  may comprise a PID velocity controller. For example, a first motor controller  6314   a  may measure a specified variable, such as the position of a motor  6314   a . The first motor controller  6314   a  may adjust a control variable, such as the speed of the motor  6314   a , based on the difference between the measured position of the motor  6314   a  and a set-point or expected position of the motor  6314   a.    
     In some forms, the motor controllers  6314   a - 6314   c  may be configured as fault detection controllers. A fault detection controller may operate a fault detection process. In some forms, the fault detection controller may operate a direct pattern recognition fault process comprising monitoring one or more sensors configured to directly indicate a fault, which may be referred to as signal processing based fault detection. In some forms, a sensor value provided by a sensor is compared to an expected value of the sensor derived from a model of the surgical process controlled by the fault detection controller, which may be referred to as model-based fault detection. Those skilled in the art will recognize that a combination of signal processing and model-based fault detection may be employed by a motor controller. 
     In some forms, the motor controllers  6314   a - 6314   c  may be configured as current/force limiting controllers. A current/force limiting controller may be configured to limit a measured value, such as the current delivered to a motor or the force exerted by a motor, to a predetermined value. For example, in one form, a first motor controller  6314   a  may be configured to limit the force exerted during a clamping operation to a predetermined value. A force sensor may monitor the force provided by a first motor  6318   a  configured to control a clamping operation of a surgical instrument. When the force value measured by the force sensor matches the predetermined value, the first motor controller  6314   a  may cease operation of the first motor  6318   a . In some forms, a motor controller  6314   a - 6314   c  may be configured to monitor the current delivered to a motor  6318   a - 6318   c . The current drawn by the motor  6318   a - 6318   c  may be indicative of one or more functions of the motor  6318   a - 6318   c , such as the speed of the motor or the force exerted by the motor during a surgical operation. If the current drawn by the motor  6318   a - 6318   c  exceeds a predetermined threshold, the motor controller  6314   a - 6314   c  may cease operation of the motor to prevent damage to a patient and to the surgical instrument. 
     In some forms, the motor controllers  6314   a - 6314   c  may provide independent verification of the main control process executed by the master controller  6306 . For example, the motor controllers  6314   a - 6314   c  may verify that the action requested by the master controller  6306  is a valid action prior to execution of the requested action. In some forms, the motor controller  6314   a - 6314   c  may use state information to verify that the requested action is valid. For example, in one form, a first motor controller  6314   a  may receive an instruction from the master controller  6306  to perform a cutting and stapling operation. The first motor controller  6314   a  may check the current state of the surgical instrument, such as, for example, checking whether the anvil assembly  190  is in a clamped position. If the state information matches a valid state for executing a cutting and stapling operation, the first motor controller  6314   a  may perform the cutting and stapling operation. However, if the state information does not match a valid state for cutting and stapling, the first motor controller  6314   a  may indicate a fault in the master controller  6306  or the main control process. Those skilled in the art will recognize that the motor controllers  6314   a - 6314   c  may comprise one or more control processes and one or more types of control processes. 
       FIG. 115  illustrates one form of a modular motor control platform  6400  comprising a master controller  6406  and four motor-controller pairs  6409   a - 6409   d . The modular motor control platform  6400  may also be implemented by the control circuit  3702  described herein above, for example, utilizing one or more processors. The modular motor control platform  6400  may be configured to control various motors. For example, a distal roll motor  6418   a  may operate in a manner similar to that described herein with respect to the end effector rotation motor  560 . An articulation motor  6418   b  may operate in a manner similar to that described herein with respect to the articulation motor  402 . A proximal roll motor  6418   c  may operate in a manner similar to that described herein with respect to the shaft rotation motor  610 . A transaction motor  6418   d  may operate in a manner similar to that described herein with respect to the firing motor  530 . 
     The master controller  6406  may be electrically coupled to one or more motor controllers  6414   a - 6414   d . The master controller  6406  may be coupled to the one or more motor controllers  6414   a - 6414   d  through a wired or wireless connection. In some forms, the motors  6418   a - 6418   d  may comprise associated motor encoders  6416   a - 6416   d  configured to provide a signal indicative of the position of the motor shaft. In some forms, the motor encoders  6416   a - 6416   d  may be omitted. In one form, the master controller  6406  may be configured to communicate with any number of motor controllers  6414   a - 6414   d , such as, for example, one to ten motor controllers. In some forms, the master controller  6406  may be configured to communicate with one or more additional peripheral controllers (not shown) wherein the peripheral controllers are configured to control one or more non-motorized surgical functions, such as, for example, ultrasonic functions, electrosurgical functions, or any other suitable function of the surgical instrument. 
     In one form, the master controller  6406  may synchronously communicate with the motor controllers  6414   a - 6414   d . The communications from the master controller  6406  may include, for example, providing instructions to execute a specific sub-routine or function of the motor controller  6414   a - 6414   d , querying the motor controller  6414   a - 6414   d  for a status update, and receiving feedback information from the motor controllers  6414   a - 6414   d . Synchronous communication may be direct communication between the master controller  6406  and the motor controllers  6414   a - 6414   d  where the communications are time synchronized. For example, in the form illustrated in  FIG. 114 , the master controller  6406  may communicate with each of the motor controllers  6414   a - 6414   d  during predefined time windows. In another form, a token may be passed between the motor controllers  6414   a - 6414   d  to allow the motor controller  6414   a - 6414   d  currently holding the token to communicate with the master controller  6406  during a predetermined time period. 
     In one form, the master controller  6406  may execute a main control process. The main control process may monitor user inputs, execute operations of the surgical instrument  10 , provide feedback to a user, or perform any other functions of the surgical instrument  10 . For example, in one form, a master controller  6406  may execute a main control process comprising a cutting and sealing operation. In some forms, the main control process may provide control signals to each of the motor controllers  6414   a - 6414   d . Execution of the individual functions of the motors  6418   a - 6418   d  may be controlled by the motor controllers  6414   a - 6414   d . In some forms, the master control process may activate or deactivate one or more of the motors  6418 - 6418   d  based on the attachment or removal of a module surgical component, such as a modular shaft  30  or implement portion  100 . The master controller  6406  may provide control signals to the motor controllers  6414   a - 6414   d  and may receive status signals from the motor controllers  6414   a - 6414   d . The status signals may include, for example, a function completion signal, a fault signal, an idle signal, or a feedback signal. 
     In some forms, the function signal may indicate the operation or completion status of a function performable by the motor-controller pairs  6409   a - 6409   d . For example, the function signal may indicate that a clamping operation is occurring or has been completed. The function signal may also indicate the success of the operation, such as, for example, indicating the amount of force applied by the tissue clamped during the clamping operation. A motor controller  6414   a - 6414   d  may generate a fault signal if the motor controller  6414   a - 6414   d  detects an error in an associated motor  6418   a - 6418   d  or in the completion of a surgical operation. The fault signal may cause the master controller  6406  to generate a fault signal to the operator, such as, for example, a visual indicator or an audible indicator. The fault signal may also cause the master controller  6406  to send control signals to the motor controllers  6414   a - 6414   d  to stop any currently executing functions. 
     An idle signal may be provided by the motor controllers  6414   a - 6414   d  to the master controller  6406  to indicate that an associated motor  6418   a - 6418   d  is idle and may be utilized to perform an associated function of the surgical instrument  10 . In one form, an idle signal may indicate that a function has been performed by a motor  6418   a - 6418   d . For example, in one form, a first motor controller  6414   a  may receive a control signal from the master controller  6406  to perform a clamping operation. The first motor controller  6414   a  may convert the control signal from the master controller  6406  into one or more control signals for the motor  6418   a . Once the motor  6418   a  has performed the indicated function, the motor controller  6414   a  may transmit an idle signal to the master controller  6406 , indicating that the motor  6418   a  has completed the requested function. 
     In various forms, a feedback signal may be provided by the motor controllers  6414   a - 6414   d  to the master controller  6406 . The master controller  6406  may have one or more associated feedback devices (not shown) to provide feedback to an operator. The feedback signals received from the motor controllers  6414   a - 6414   d  may be converted to control signals for the feedback devices by the master controller  6406 . In some forms, the motor controllers  6414   a - 6414   d  may provide feedback signals directly to a feedback device. 
     In some forms, the synchronous communication between the master controller  6406  and the motor controllers  6414   a - 6414   d  may be interrupted by an override signal. The override signal may cause the master controller  6406  to cease synchronous communication and to communicate with the motor controller  6414   a  generating the override signal. In various forms, the override signal may be generated by a motor controller  6414   a  as the result of a failure of a motor, an input signal from the user, or based on a predetermined threshold in one or more feedback signals. The override signal may cause the master controller  6406  to send a signal to each of the motor controllers  6414   a - 6414   d  to cease all operation of the motors  6418   a - 6418   d  until the condition that caused the generation of the override signal has been resolved. In one form, the master controller  6406  may generate a signal for a feedback device to notify the operator of the override signal. 
       FIG. 116  illustrates one form of a dual-controller modular motor control platform  6500 . The platform  6500  may also be implemented by the control circuit  3702 , as described herein. The dual-controller modular motor control platform  6500  comprises a master controller  6506 , a slave controller  6507 , and four motor-controller pairs  6509   a - 6509   d . The modular motor control platform  6400  may be configured to control motors  6518   a ,  6518   b ,  6518   c ,  6518   c . For example, a distal roll motor  6518   a  may operate in a manner similar to that described herein with respect to the end effector rotation motor  560 . An articulation motor  6518   b  may operate in a manner similar to that described herein with respect to the articulation motor  402 . A proximal roll motor  6518   c  may operate in a manner similar to that described herein with respect to the shaft rotation motor  610 . A transaction motor  6518   d  may operate in a manner similar to that described herein with respect to the firing motor  530 . 
     The modular motor control platform  6400  may be configured to control the articulation motor  402 , the firing motor  530 , the end effector rotation or “distal roll” motor  560 , and the shaft rotation or “proximal roll” motor  610 . The master controller  6506  and the slave controller  6507  may each be associated with a subset of the available motor controllers. For example, in the illustrated form, the master controller  6506  is associated with the first and second motor controllers  6526   a - 6526   b  and the slave controller  6507  is associated with the third and fourth motor controllers  6526   c - 6526   d . The master controller  6506  and the slave controller  6507  may be in electrical communication. In some forms, the slave controller  6507  may located on the distal circuit board  810  or the proximal circuit board  820 . The slave controller  6507  may reduce the load on the master controller  6506  by reducing the number of motor controllers  6526   a - 6526   d  that the master controller  6506  must communicate with and control. The master controller  6506  and the slave controller  6507  may receive one or more controller inputs  6508 . 
     In one form, the master controller  6506  may provide control signals directly to a first motor controller  6526   a  and a second motor controller  6526 . The master controller  6506  may also provide control signals to the slave controller  6507 . The slave controller may provide control signals to a third motor controller  6526   c  and a fourth motor controller  6526   d . By reducing the number of motor controllers  6526   a - 6526   d  that the master controller  6506  must query and control, the dual-controller modular motor control platform  6500  may increase response times or dedicate additional processing load of the master controller  6506  to other tasks. In one form, the master controller  6506  may execute a main control process and the slave controller  6507  may execute a slave control process to generate one or more signals for the motor controllers  6526   a - 6526   d  based on input from the master controller  6506 . In one form, the slave controller  6507  may receive controller inputs from one or more user controls, such as, for example, a clamping button or a firing switch. In one form, the master controller  6506  may communicate with one or more slave controllers  6507  and may not provide any control signals directly to the motor controllers  6526   a - 6526   d.    
     In one form, additional slave controllers  6507  may be added to the system to control additional motor controllers or surgical modules. In one form, the slave controller  6507  may only be utilized when a predefined threshold of motor controllers is required. For example, in the form shown in  FIG. 115 , four motor controllers  6526   a - 6526   d  are connected to the dual-controller modular motor control platform  6500 . The master controller  6506  and the slave controller  6507  are each associated with two motor controllers  6526   a - 6526   d . Deactivation of one or more motors, such as, for example, by replacing the shaft  30  with a different shaft requiring only to motors for articulation, may result in deactivation of the slave controller  6507 , as the additional processing power of the slave controller  6507  is not required to reduce processing load on the master controller  6506 . In some forms, deactivation of one or more motor controllers  6526   a - 6526   d  may result in the remaining motor controllers being assigned to an idle slave controller  6507 . For example, deactivation of the third and fourth motors  6518   c ,  6518   d  would result in the slave controller  6507  being idle. The second motor controller  6526   b  may be disconnected from the master controller  6506  and connected to the slave controller  6507  to lessen the processing load of the master controller  6506 . One or more load balancing processes may be executed as part of the main control process to ensure optimized distribution of control between the master controller  6506  and one or more slave controllers  6507 . 
     Referring now back to  FIGS. 114-116 , a method for controlling a modular surgical instrument  10  comprising multiple motor controllers may be disclosed. Although the method for controlling a modular surgical instrument  10  is discussed with respect to  FIGS. 114-116 , those skilled in the art will recognize that the method may be employed with respect to any embodiment of the surgical instrument, or the various control platforms described herein. The method may comprise generating, by a master controller  6506 , a main control process comprising one or more control signals. The method may further comprise transmitting, from the master controller  6506  to one or more motor controllers  6526   a - 6526   d , the generated control signals. The motor controllers  6526   a - 6526   d  may receive the transmitted control signals. In some forms, the subset of the control signals received by a first motor controller  6526   a  may comprise the control signals transmitted by the master controller  6506  during a specific time period in which the master controller  6506  and the first motor controller  6526   a  are in synchronous communication. The method may further comprise controlling, by the motor controllers  6526   a - 6526   d , one or more associated motors  6518   a - 6518   d  based on the control signals received from the master controller  6506 . 
     In some forms, the method may comprise transmitting, by the master controller  6506 , one or more control signals to a slave controller  6507 . The slave controller  6507  may be in electrical communication with one or more motor controllers  6526   c - 6526   d . The slave controller  6507  may execute a slave control process comprising generating one or more motor control signals based on input received from the master controller  6506 . The slave control process may further comprise transmitting, by the slave controller  6507 , the motor control signals to one or more electrically coupled motor controllers  6526   c - 6526   d . The method may further comprise controlling, by the motor controllers  6526   c - 6526   d , one or more associated motors in response to the received motor control signals. In various forms, a subset of the generated motor control signals may be synchronously transmitted to each of the motor controllers  6526   c - 6526   d  during a predetermined time period. 
       FIG. 117  illustrates one form of a main control process  6600  that may be executed by a master controller, such as, for example, the master controllers shown in  FIGS. 114-116  or any other suitable master controller. In one form, the surgical instrument  10  may comprise four motors, such as, for example the articulation motor  402 , the firing motor  530 , the end effector rotation or “distal roll” motor  560 , and the shaft rotation or “proximal roll” motor  610  and a joystick  842 . The surgical instrument  10  may be configured to perform a distal rotation function, a grasping function, a clamping function, and a firing function. The surgical instrument  10  may comprise one or more buttons for controlling the various operations of the surgical instrument  10 , such as, for example a home button, an unload button, a grasping button, a clamping button, or a fire button. The surgical instrument  10  may further comprise a light-emitting diode (LED) to provide visual feedback to a user regarding the operation of the surgical instrument  10 . 
     In some forms, when the surgical instrument  10  is activated, the master controller  6406  places the device into a default mode. In the illustrated main control process  6600 , the default mode is the articulation state  6602 . The articulation state  6602  may comprise activation of three of the four available motors. The activated motors may control the rotation of the shaft  30  (e.g., the shaft rotation motor  610 ), the end effector  102  (e.g., the end effector rotation motor  560 ), and/or the articulation of the end effector  102  (e.g., the articulation motor  410 ). In the default articulation mode, the joystick  842  may be active. In the articulation state  6602 , the joystick  842  may be used to control the articulation or rotation of the shaft  30  and the end effector  102 . The distal rotation function may be active (or available) while the grasping, clamping, and firing functions are unavailable. The home button may also be activated in the default state. The LED may be green to indicate the surgical instrument  10  is in a state during which the surgical instrument  10  may be safely moved. 
     A user may press the home button  6604  causing the surgical instrument  10  to return to a home state  6606 , e.g., a starting state in which the end effector  102  is straightened with respect to the shaft  30  and the shaft  30  and end effector  102  are returned to a zero rotation state. The home state  6606  may be useful for moving from one operation to another or may allow a user to quickly reorient the surgical instrument  10  during operation. Once the home state  6606  has been reached, the master control process  6600  may return  6605  to the default articulation state  6602 . 
     In one form, the end effector  102 , illustrated in  FIGS. 1 and 2 , may be releasably connected to the shaft  30  to allow different implements to be attached to the shaft  30 . The shaft  30  may be releasably connected to the handle  20  to allow various shafts to be attached to the surgical instrument  10 . In one form, the master controller  6406  may sense the ejection  6608  of an end effector  102  or a shaft  30  from the surgical instrument  10  and may disable operation of the surgical instrument  10  until a new shaft or implement portion has been attached to the surgical instrument  10  and the surgical instrument  10  has been returned to a home state  6606 . After the master control process  6600  has detected a new end effector  102  and has returned to the home state  6606 , the master control process  6600  may enter the default state  6602 . 
     In one form, the surgical instrument  10  may have an end effector  102  attached. The end effector  102  may be configured to perform a grasping function. The grasping function may comprise grasping an area of tissue between the anvil assembly  190  and the cartridge  130  of the end effector  102 . The surgical instrument  10  may comprise a grasping button to activate a grasping function. When a user presses  6614  the grasping button, the surgical instrument  10  may enter a grasping mode  6616 , locking out movement of the end effector  102 , such as rotation or articulation with respect to the shaft  30 . The grasping mode  6616  may activate a fourth motor (e.g., the firing motor  530 ) to cause a portion of the end effector  102  to grasp a tissue section, such as, for example, moving the anvil assembly  190  from an open position to a closed position. A clamping button may be activated when the surgical instrument  10  enters a grasping state. 
     In some forms, a clinician may press  6620  a clamping button, causing the surgical instrument  10  to enter a clamp mode  6622 . In the clamp mode  6622 , the surgical instrument  10  may lock out the fourth motor to prevent release of the tissue section during a subsequent operation. The clamp mode  6622  may activate a fire button located on the handle  20 . Once the surgical instrument  10  has entered the clamp mode  6622 , the master controller  6406  may change the LED to blue to indicate to the clinician that tissue has been clamped in the anvil assembly  190  and that the surgical instrument  10  may be fired to cause a stapling and cutting operation. 
     A clinician may press  6626  a fire button to cause the surgical instrument  10  to enter a fire mode  6628 . In the fire mode  6628 , the surgical instrument  10  may deactivate the motors configured to control movement of the surgical instrument  10 , such as, for example, motors  1 - 3 . The fire mode  6628  may activate the fourth motor which may be configurable to control a stapling and cutting operation as described above. The fire button may be held down, causing the master controller  6406  to generate control signals for the motor controller associated with the fourth motor to activate the stapling and cutting operation, causing a cutting portion  164  and/or a sled  170  to advance within a staple cartridge  130  located in the end effector  102 . During the firing sequence, the LED may be set to red by the master controller  6406  to alert the clinician that the surgical instrument  10  is firing. A “fired tag” may be set to true by the master controller  6406 , indicating that the surgical instrument has been fired and may not be fired again. The master controller  6406  or the motor controller associated with the fourth motor may automatically retract the cutting portion  164  when the cutting portion  164  has reached the distal end of the end effector  102 . Once the cutting portion  164  has completed the reverse stroke and returned to its starting position, the master control process  6600  may return  6630  to the clamp state  6622 . 
     A clinician may deactivate  6624  the clamp state  6622  by pressing the clamp button. The master control process  6600  will generate one or more control signals to return to the grasping state  6616  when the clamping state  6622  is deactivated. The clinician may then release  6618  the grasping state  6616  and transition into the articulation state  6602 , or any other suitable default state. Those skilled in the art will recognize that the master control process  6600  may be modified to accommodate any surgical operation or function performable by the surgical instrument  10  or any attached surgical module. In some forms, the master control process  6600  may be automatically configured based on the attached shafts, end effectors, or power modules. 
     In accordance with one general form, there is provided a surgical instrument comprising a handle assembly that is configured to simultaneously and independently electrically generate at least two discrete rotary control motions. The surgical instrument may further include an elongate shaft assembly that operably interfaces with the handle assembly for independently and simultaneously receiving and transmitting the at least two discrete rotary control motions to an end effector operably coupled to the elongate shaft assembly. 
     In accordance with another general form, there is provided a surgical instrument that comprises a handle assembly that is configured to simultaneously and independently generate at least three discrete rotary control motions. The surgical instrument may further include an elongate shaft assembly that operably interfaces with the handle assembly for independently and simultaneously receiving and transmitting the at least three discrete rotary control motions to an end effector operably coupled to the elongate shaft assembly. 
     In accordance with another general form, there is provided a surgical instrument that comprises a drive system that is configured to electrically generate a plurality of discrete rotary control motions. The surgical instrument may further include an elongate shaft assembly that is operably coupled to the drive system for receiving a first rotary control motion therefrom for rotating the elongate shaft assembly about a shaft axis. The elongate shaft assembly may be configured to receive and transmit a second rotary control motion from the drive system to a surgical end effector that is operably coupled to the elongate shaft assembly to cause the surgical end effector to rotate about the shaft axis relative to the elongate shaft assembly. The elongate shaft assembly may be further configured to receive and transmit a third rotary control motion from the drive system to an articulation joint that communicates with the elongate shaft assembly and the surgical end effector to articulate the surgical end effector about an articulation axis that is substantially transverse to the shaft axis. 
     In accordance with still another general form, there is provided an articulation joint for a surgical instrument that includes an elongate shaft assembly and a drive system that is configured to generate and apply a plurality of rotary control motions to the elongate shaft assembly. In at least one form, the articulation joint comprises a proximal joint portion that is coupled to the elongate shaft assembly and a distal joint portion that is movably coupled to the proximal joint portion and is configured to interface with a surgical end effector. A first gear train may operably interface with a proximal firing shaft portion of the elongate shaft assembly. A distal firing shaft may operably interface with the surgical end effector for transmitting a rotary firing motion from the proximal firing shaft to the surgical end effector while facilitating articulation of the distal joint portion relative to the proximal joint portion. A second gear train may operably interface with a proximal rotation shaft portion of the elongate shaft assembly for transmitting a distal rotational control motion to the surgical end effector to cause the surgical end effector to rotate relative to the elongate shaft assembly while facilitating articulation of the distal joint portion relative to the proximal joint portion. 
     In accordance with another general form, there is provided an articulation joint for a surgical instrument that has an elongate shaft assembly and a drive system that is configured to generate and apply a plurality of rotary control motions to the elongate shaft assembly. In at least one form, the articulation joint includes a proximal clevis that is coupled to the elongate shaft assembly and a distal clevis that is pivotally pinned to the proximal clevis for selective pivotal travel relative thereto about an articulation axis that is substantially transverse to a shaft axis that is defined by the elongate shaft assembly. A first gear train may be supported in a gear area defined between the proximal and distal devises such that no portion of the first gear train extends radially outwardly beyond any portion of the articulation joint. The first gear train may operably interface with a proximal firing shaft portion of the elongate shaft assembly. A distal firing shaft may operably interface with the surgical end effector for transmitting a rotary firing motion from the proximal firing shaft to the surgical end effector while facilitating pivotal travel of the distal clevis relative to the proximal clevis. A second gear train may be supported in the gear area such that no portion of the first gear train extends radially outwardly beyond any portion of the articulation joint. The second gear train may operably interface with a proximal rotation shaft portion of the elongate shaft assembly for transmitting a distal rotational control motion to the surgical end effector to cause the surgical end effector to rotate relative to the elongate shaft assembly while facilitating articulation of the distal clevis relative to the proximal clevis. 
     In accordance with another general form, there is provided a surgical instrument that includes a drive system that is configured to generate a plurality of rotary control motions. An elongate shaft assembly operably interfaces with the drive system and may comprise an outer shaft segment that operably interfaces with the drive system to receive distal rotational control motions therefrom. An articulation shaft may operably interface with the drive system to receive rotary articulation motions therefrom. The elongate shaft assembly may further include a proximal firing shaft segment that operably interfaces with the drive system to receive rotary firing motions therefrom. The surgical instrument may further include an articulation joint that may include a proximal clevis that is coupled to the elongate shaft assembly and a distal clevis that is pivotally pinned to the proximal clevis for selective pivotal travel relative thereto about an articulation axis that is substantially transverse to a shaft axis defined by the elongate shaft assembly. A coupling assembly may rotatably interface with the distal clevis and be configured for attachment to a surgical end effector. A distal firing shaft segment may be operably supported by the coupling assembly and be configured to interface with a drive shaft portion of the surgical end effector. A first gear train may operably interface with the proximal firing shaft segment and the distal firing shaft segment for transmitting the rotary firing motions from the proximal firing shaft segment to the distal firing shaft segment while enabling the distal clevis to be selectively pivoted relative to the proximal clevis. A second gear train may operably interface with a proximal rotation shaft for transmitting the distal rotational control motions to the coupling assembly while enabling the distal clevis to be selectively pivoted relative to the proximal clevis. An articulation drive link may interface with the articulation shaft and the distal clevis and be constrained to move axially relative to the articulation joint in response to applications of the rotary articulation motions to the articulation shaft. 
     In accordance with yet another general form, there is provided a cover for an articulation joint that is supported in an elongate shaft assembly of a surgical instrument that is operably coupled to a surgical end effector that has at least one end effector conductor therein. In at least one form, the cover comprises a non electrically-conductive hollow body that has an open distal end and an open proximal end and a joint-receiving passage that extends therebetween for receiving the articulation joint therein. The hollow body is configured to permit portions of the articulation joint to be selectively articulated relative to each other while substantially enclosing the portions within the hollow body. At least one electrically conductive pathway extends from the distal end of the hollow body to the proximal end of the hollow body. Each of the at least one electrically conductive pathways has a distal end portion that is configured to electrically contact a corresponding end effector conductor when the end effector has been coupled to the elongate shaft assembly and a proximal end portion that is configured to electrically contact a corresponding shaft conductor in the elongate shaft assembly. 
     In accordance with another general form, there is provided a surgical instrument that includes an elongate shaft assembly that has at least one electrical shaft conductor therein and an articulation joint. In at least one form, the articulation joint includes a proximal joint portion that is coupled to the elongate shaft assembly. A distal joint portion is movably coupled to the proximal joint portion for selective articulation relative thereto. A coupler assembly is rotatably coupled to the distal joint portion for selective rotation relative thereto. The coupler assembly may be configured to be detachably coupled to the surgical end effector and form an electrically conductive coupler pathway from an end effector conductor in the end effector to the articulation joint. The surgical instrument may further include an articulation joint conductor that contacts the conductive coupler pathway and traverses the articulation joint to contact the corresponding shaft conductor to form an electrically-conductive path therebetween. 
     In accordance with another general form, there is provided a surgical instrument that includes a control system that contains at least one electrical control component. The surgical instrument further includes an elongate shaft assembly that has an electrical shaft conductor that operably communicates with at least one of the electrical control components. The surgical instrument may further include an articulation joint that includes a proximal clevis that is coupled to the elongate shaft assembly. A distal clevis is pivotally coupled to the proximal clevis for selective pivotal travel relative thereto. The surgical instrument may further include a coupler assembly that is coupled to the distal clevis and a surgical end effector that is releasably coupled to the coupler assembly. The surgical end effector may include an end effector conductor that is arranged for electrical contact with an electrically conductive coupler pathway formed in the coupler assembly when the surgical end effector has been coupled to the coupler assembly. An articulation joint conductor may traverse the articulation joint and be in electrical contact with the conductive pathway through the coupler assembly and the shaft conductor. 
     In accordance with yet another general form, there is provided a surgical instrument that includes a handle assembly that has an elongate shaft assembly operably coupled thereto and configured for operably attachment to a surgical end effector. A motor is supported by the handle assembly and is configured to apply a rotary motion to one of the elongate shaft or the surgical end effector coupled thereto. A thumbwheel control assembly is operably supported on the handle assembly and communicates with the motor such that when an actuator portion of the thumbwheel control assembly is pivoted in a first direction, the motor applies a rotary motion to one of the elongate shaft assembly and end effector in the first direction and when the actuator portion is pivoted in a second direction, the motor applies the rotary motion to one of the elongate shaft assembly and end effector in the second direction. 
     In accordance with another general form, there is provided a surgical instrument that includes a handle assembly that has an elongate shaft assembly rotatably coupled thereto and is configured for operably attachment to a surgical end effector. A motor is supported by the handle assembly and is configured to apply a rotary motion to the elongate shaft assembly for selective rotation about a shaft axis. The surgical instrument further includes a thumbwheel control assembly that includes a thumbwheel actuator member that is pivotally supported relative to the handle assembly. A first magnet is supported on the thumbwheel actuator member and a second magnet is supported on the thumbwheel actuator member. A stationary sensor is centrally disposed between the first and second magnets when the thumbwheel actuator member is in an unactuated position. The stationary sensor communicates with the motor such that when the thumbwheel actuator is pivoted in a first direction, the motor applies a rotary motion to the elongate shaft assembly in the first direction and when the thumbwheel actuator member is pivoted in a second direction, the motor applies the rotary motion to the elongate shaft assembly in the second direction. 
     In accordance with another general form, there is provided a surgical instrument that includes a handle assembly that has an elongate shaft assembly rotatably coupled thereto and configured for operably attachment to a surgical end effector such that the end effector may be selectively rotated about a shaft axis relative to the elongate shaft assembly. A motor is supported by the handle assembly and is configured to apply a rotary motion to the end effector or coupler portion of the elongate shaft assembly to which the end effector is coupled for selective rotation thereof about the shaft axis. The surgical instrument further includes a thumbwheel control assembly that includes a thumbwheel actuator member that is pivotally supported relative to the handle assembly. First and second magnets are supported on the thumbwheel actuator member. A stationary sensor is centrally disposed between the first and second magnets when the thumbwheel actuator member is in an unactuated position. The stationary sensor communicates with the motor such that when the thumbwheel actuator is pivoted in a first direction, the motor applies a rotary motion to the end effector or coupler position in the first direction and when the thumbwheel actuator member is pivoted in a second direction, the motor applies the rotary motion to the end effector or coupler portion in the second direction. 
     In accordance with yet another general form, there is provided a surgical instrument that includes a housing that supports a plurality of motors. The surgical instrument further includes a joystick control assembly that includes a first switch assembly that is movably supported by the housing and includes a joystick that is movably mounted thereto such that pivotal movement of the joystick relative to the first switch assembly causes at least one corresponding control signal to be sent to at least one of the motors communicating therewith. The joystick assembly further includes a second switch assembly that comprises a first sensor and a second sensor that is movable with the first switch assembly such that movement of the second sensor relative to the first sensor causes at least one other control signal to be sent to another one of the motors communicating therewith. 
     In accordance with another general form, there is provided a surgical instrument that includes a handle assembly that has an elongate shaft assembly rotatably supported relative thereto. A proximal roll motor is supported by the handle assembly and is configured to apply proximal rotary motions to the elongate shaft assembly to cause the elongate shaft assembly to rotate relative to the handle assembly about a shaft axis. A surgical end effector is operably coupled to the elongate shaft assembly and is configured to perform a surgical procedure upon application of at least one firing motion thereto. A firing motor is supported by the handle assembly and is configured to apply firing motions to a portion of the elongate shaft assembly for transfer to the surgical end effector. The surgical instrument further includes a joystick control assembly that comprises a first switch assembly that is movably supported by the handle assembly and includes a joystick that is movably mounted thereto such that pivotal movement of the joystick relative to the first switch assembly causes at least one corresponding control signal to be sent to the proximal roll motor. The joystick control assembly further includes a second switch assembly that comprises a first sensor and a second sensor that is movable with the first switch assembly such that movement of the second sensor relative to the first sensor causes at least one other control signal to be sent to the firing motor. 
     In accordance with another general form, there is provided a surgical instrument that includes a handle assembly that has an elongate shaft assembly rotatably supported relative thereto. The surgical instrument further includes an articulation joint that comprises a proximal joint portion that is coupled to the elongate shaft assembly and a distal joint portion that is movably coupled to the proximal joint portion. An articulation motor is supported by the handle assembly and is configured to apply articulation motions to the articulation joint to cause the distal joint portion to move relative to the proximal joint portion. A surgical end effector is operably coupled to the elongate shaft assembly and is configured to perform a surgical procedure upon application of at least one firing motion thereto. A firing motor is supported by the handle assembly and is configured to apply firing motions to a portion of the elongate shaft assembly for transfer to the surgical end effector. The surgical instrument further includes a joystick control assembly that comprises a first switch assembly that is movably supported by the handle assembly and includes a joystick that is movably mounted thereto such that pivotal movement of the joystick relative to the first switch assembly causes at least one corresponding control signal to be sent to the articulation motor. The joystick assembly further includes a second switch assembly that comprises a first sensor and a second sensor that is movable with the first switch assembly such that movement of the second sensor relative to the first sensor causes at least one other control signal to be sent to the firing motor. 
     In accordance with another general form, there is provided a surgical instrument for acting on tissue. The instrument comprises at least one processor and operatively associate memory, at least one motor in communication with the processor and at least one actuation device. The processor is programmed to receive from a removable implement portion a first variable describing the removable implement. The processor is also programmed to apply the first variable to an instrument control algorithm. Further, the processor is programmed to receive an input control signal from the actuation device and control the at least one motor to operate the surgical instrument in conjunction with the removable implement in accordance with the instrument control algorithm considering the input control signal. 
     In accordance with an additional general form, the processor may be programmed to receive from a removable implement an implement control algorithm describing operation of the surgical instrument in conjunction with the removable implement. The processor may also be programmed to receive an input control signal from the actuation device and control the at least one motor to operate the surgical instrument in conjunction with the removable implement in accordance with the implement control algorithm considering the input control signal. 
     In accordance with another general form, a surgical instrument configured to relay a low-power signal from an end effector to a remote device may be disclosed. The surgical instrument may comprise a handle, a shaft extending distally from the handle, and an end effector attached to the distal end of the shaft. A sensor may be disposed in the end effector. The sensor may generate a signal indicative of a condition at the end effector. A transmitter may be located in the end effector. The transmitter may transmit the signal from the sensor at a first power level. The signal may be received by a relay station located in the handle of the surgical instrument. The relay station is configured to amplify and retransmit the signal at a second power level, wherein the second power level is higher than the first power level. 
     In accordance with an additional general form, a relay station for relaying a signal from an end effector of a surgical instrument to a remote device may be disclosed. The relay station comprises a receiver configured to receive a signal from a sensor disposed in an end effector. The signal is transmitted at a first power level. The relay station further comprises an amplifier configured to amplify the signal to a second power level. A transmitter is configured to transmit the signal at the second power level. The second power level is higher than the first power level. 
     In accordance with a general form, a method for relaying a signal received from a sensing module in an end effector may be disclosed. The method comprises generating, by a sensor, a first signal indicative of a condition at a surgical end effector. The sensor is located in the end effector. The method further comprises transmitting, using a transmitter, the first signal at a first power level and receiving the transmitted signal, using a receiver, at a relay station. The first signal is amplified by the relay station using an amplifier to a high-power signal comprising a second power level. The second power level is greater than the first power level. The high-power signal is transmitted, using the relay station, at the second power level. The high-power signal is received by a remote device, such as a video monitor. The video monitor displays a graphical representation of the condition at the surgical end effector. 
     Some portions of the above are presented in terms of methods and symbolic representations of operations on data bits within a computer memory. These descriptions and representations are the means used by those skilled in the art to most effectively convey the substance of their work to others skilled in the art. A method is here, and generally, conceived to be a self-consistent sequence of actions (instructions) leading to a desired result. The actions are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical, magnetic or optical signals capable of being stored, transferred, combined, compared and otherwise manipulated. It is convenient, at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. Furthermore, it is also convenient, at times, to refer to certain arrangements of actions requiring physical manipulations of physical quantities as modules or code devices, without loss of generality. 
     Certain aspects of the present invention include process steps and instructions described herein in the form of a method. It should be noted that the process steps and instructions of the present invention can be embodied in software, firmware or hardware, and when embodied in software, can be downloaded to reside on and be operated from different platforms used by a variety of operating systems. 
     The present invention also relates to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, or it may comprise a general-purpose computer selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a computer readable storage medium, such as, but not limited to, any type of disk including floppy disks, optical disks, CD-ROMs, magnetic-optical disks, read-only memories (ROMs), random access memories (RAMs), EPROMs, EEPROMs, magnetic or optical cards, application specific integrated circuits (ASICs), or any type of media suitable for storing electronic instructions, and each coupled to a computer system bus. Furthermore, the computers and computer systems referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability. 
     The methods and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems may also be used with programs in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatus to perform the required method actions. The required structure for a variety of these systems will appear from the above description. In addition, the present invention is not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the present invention as described herein, and any references above to specific languages are provided for disclosure of enablement and best mode of the present invention. 
     In various forms, a surgical instrument configured to relay a low-power signal from an end effector to a remote device is disclosed. The surgical instrument may comprise a handle, a shaft extending distally from the handle, and an end effector attached to the distal end of the shaft. A sensor may be disposed in the end effector. The sensor may generate a signal indicative of a condition at the end effector. A transmitter may be located in the end effector. The transmitter may transmit the signal from the sensor at a first power level. The signal may be received by a relay station located in the handle of the surgical instrument. The relay station is configured to amplify and retransmit the signal at a second power level, wherein the second power level is higher than the first power level. 
     In various forms, a relay station for relaying a signal from an end effector of a surgical instrument to a remote device is disclosed. The relay station comprises a receiver configured to receive a signal from a sensor disposed in an end effector. The signal is transmitted at a first power level. The relay station further comprises an amplifier configured to amplify the signal to a second power level. A transmitter is configured to transmit the signal at the second power level. The second power level is higher than the first power level. 
     In various forms, a method for relaying a signal received from a sensing module in an end effector is disclosed. The method comprises generating, by a sensor, a first signal indicative of a condition at a surgical end effector. The sensor is located in the end effector. The method further comprises transmitting, using a transmitter, the first signal at a first power level and receiving the transmitted signal, using a receiver, at a relay station. The first signal is amplified by the relay station using an amplifier to a high-power signal comprising a second power level. The second power level is greater than the first power level. The high-power signal is transmitted, using the relay station, at the second power level. The high-power signal is received by a remote device, such as a video monitor. The video monitor displays a graphical representation of the condition at the surgical end effector. 
     In various forms, a sensor-straightened end effector is disclosed. The sensor-straightened end effector may comprise an end effector coupled to a shaft at an articulation point. The end effector may be articulable at an angle with respect to the shaft. A sensor may be disposed on the sensor-straightened end effector, such as on the shaft or on the end effector. The sensor is configured to detect a gross proximal movement of the surgical instrument. When detecting a gross proximal movement, the sensor may generate a signal to control a motor to straighten the end effector with respect to the shaft. 
     In various forms, a surgical instrument comprising a sensor-straightened end effector is disclosed. The surgical instrument may comprise a handle. A shaft may extend distally from the handle. A motor may be disposed within the handle for controlling an articulation of the surgical instrument. An articulating end effector is disposed at the distal end of the shaft. A sensor may be disposed in the handle, the shaft, or the end effector. The sensor may be configured to detect a gross proximal movement of the surgical instrument. When the sensor detects the gross proximal movement, the sensor may activate a powered straightening process, causing the motor to straighten the articulated end effector. In some forms, multiple sensors may provide redundant checks for the straightening process. 
     In various forms, a method for operating a surgical instrument comprising a sensor straightened end effector is disclosed. The method may comprise detecting, by a first sensor, a proximal movement of the surgical instrument. The first sensor may be located in any suitable section of the surgical instrument, such as the handle, shaft, or end effector. The first sensor may be an accelerometer, a magnetic sensor, or any other suitable sensor type. The sensor may generate a signal indicating that a gross proximal movement has been detected. The method may further comprise receiving, by a motor, the generated signal from the first sensor. The motor may straighten an angle of articulation of the motor-controlled articulating end effector in response to the received signal. A second sensor may generate a second signal to provide a redundant check. 
     In various forms, the present disclosure is directed towards a motor-driven surgical instrument comprising a modular motor control platform. A master controller may execute a main control process for controlling one or more operations of the surgical instrument. A first motor controller and a second motor controller may be operatively coupled to the master controller. The first motor controller may have an associated first motor and the second motor controller may have an associated second motor. The main control process may generate control signals for the first and second motor controllers. The first and second motor controllers may operate the first and second motors in response to the control signals. In some forms, the modular motor control system may comprise a slave controller configured to control one or more of the motor controllers based on one or more control signals received by the slave controller from the master controller. 
     In various forms, a modular motor control system may comprise one or more motor controllers each having an associated motor. The one or more motor controllers may be in communication with a master controller. The master controller may be configured to provide control signals to the motor controllers as part of a main control process. The motor controllers may control the associated motors in response to the received control signals. In some forms, the one or more motor controllers and the associated motors may be located within a handle adapted to receive a modular shaft, a modular end effector, and a modular power supply. The handle may provide an interface between the motors and the modular shaft and end effector. 
     In various forms, a surgical instrument may include a modular motor control system. The surgical instrument may comprise a master controller. The surgical instrument may be configured to receive modular surgical components, such as a modular shaft and implement portion. The surgical instrument may have one or more motors and associated motor controllers mounted therein. The motor controllers may be operatively coupled to the motors. The motors may be configured to control one or more movements of an attached shaft or implement portion. The master controller and the motor controllers may be in electrical communication. The master controller may be configured to provide one or more control signals to the motor controllers as part of the main control process. The motor controllers may control the motors in response to the received control signals. 
     In various forms, a method for controlling a motor-driven surgical instrument is disclosed. The method may comprise generating, by a master controller, one or more control signals. A first control signal may be transmitted to a first motor controller configured to control a first motor. The first motor controller may operate the first motor in response to the first control signal received from the master controller. A second control signal may be transmitted to a second motor controller configured to a control a second motor. The second motor controller may operate the second motor in response to the second control signal received from the master controller. In some forms, the second control signal may be generated by a slave controller. 
     In accordance with one general form, there is provided a surgical instrument comprising a drive motor and a drive member that is movable by the drive motor through a drive stroke between a home position and an end of stroke position. The end of stroke position extends between a first position and a second position. A mechanical stop may be disposed at or near the end of stroke position and may be structured to increase resistance to the movement of the drive member through the drive stroke from the first position to the second position. The mechanical stop may comprise a bumper and a resistance member. The bumper may be movable from the first position to the second position and be configured to contact the drive member at the first position. The resistance member may be operatively coupled to the bumper and configured to increase resistance to movement of the drive member from the first position to the second position. The resistance member may be configured to decelerate the drive member prior to the drive member actuating to the second position. In one form, the resistance member is structured to be compressible to progressively increase the resistance to the movement of the drive member between the first position and the second position. The resistance member may in one form comprise a spring. The bumpers may comprise contact surfaces that are dimensioned to complement a dimension of a drive member surface contacted at the first position. 
     In one form, a control system is configured to detect a current spike associated with the increased resistance to the movement of the drive member. The control system may monitor voltage associated with the delivery of power to the drive motor to detect the current spike. The current spike may comprise a predetermined threshold current. The predetermined threshold current may comprise at least one predetermined threshold current differential over at least one defined time period. When the control system detects the current spike, delivery of power to the drive motor may be interrupted. In one form, the mechanical stop may further comprise a hard stop that may prevent movement of the drive member beyond the second position. 
     In accordance with one general form, there is provided a mechanical stop for use in a surgical instrument to produce a detectable current spike associated with an electromechanical stop. For example, the mechanical stop may be disposed at or near an end of stroke associated with a drive stroke of a drive member. The end of stroke may extend between a first position and a second position. The mechanical stop may comprise one or more bumpers and one or more resistance members. The bumpers may be movable from the first position to the second position and may be configured to contact the drive member at the first position. The resistance members may be operatively coupled to the bumpers and configured to increase resistance to movement of the drive member from the first position to the second position to produce the current spike. The resistance members may be configured to decelerate the drive member prior to the drive member actuating to the second position. One or more of the resistance members may be structured to be compressible to progressively increase the resistance to the movement of the drive member between the first position and the second position. One or more resistance members may also be structured to be compressible and may comprise at least one spring. The bumpers may comprise contact surfaces that are dimensioned to complement a dimension of a drive member surface that is contacted at the first position. The current spike associated with the increased resistance may be detectable by a control system associated with the electromechanical surgical instrument. The control system may be configured to monitor voltage associated with power delivery to a drive motor and to interrupt the delivery of power to the drive motor when the current spike comprises at least one predetermined threshold current. At least one threshold current may comprise a current differential over at least one defined time period. In one form, the mechanical stop further comprises a hard stop for preventing movement of the drive member beyond the second position. 
     The devices disclosed herein can be designed to be disposed of after a single use, or they can be designed to be used multiple times. In either case, however, the device can be reconditioned for reuse after at least one use. Reconditioning can include any combination of the steps of disassembly of the device, followed by cleaning or replacement of particular pieces, and subsequent reassembly. In particular, the device can be disassembled, and any number of the particular pieces or parts of the device can be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, the device can be reassembled for subsequent use either at a reconditioning facility, or by a surgical team immediately prior to a surgical procedure. Those skilled in the art will appreciate that reconditioning of a device can utilize a variety of techniques for disassembly, cleaning/replacement, and reassembly. Use of such techniques, and the resulting reconditioned device, are all within the scope of the present application. 
     Preferably, the invention described herein will be processed before surgery. First, a new or used instrument is obtained and if necessary cleaned. The instrument can then be sterilized. In one sterilization technique, the instrument is placed in a closed and sealed container, such as a plastic or TYVEK bag. The container and instrument are then placed in a field of radiation that can penetrate the container, such as gamma radiation, x-rays, or high-energy electrons. The radiation kills bacteria on the instrument and in the container. The sterilized instrument can then be stored in the sterile container. The sealed container keeps the instrument sterile until it is opened in the medical facility. 
     Any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated materials does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material. 
     While this invention has been described as having exemplary designs, the present invention may be further modified within the spirit and scope of the disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.