Patent Publication Number: US-2022226048-A1

Title: Robotic surgical instruments with rack-based translation and firing transmission

Description:
TECHNICAL FIELD 
     The systems and methods disclosed herein are directed to robotic surgical tools and, more particularly to, robotic surgical instruments that incorporate a rack-based translation and firing transmission system. 
     BACKGROUND 
     Minimally invasive surgical (MIS) instruments are often preferred over traditional open surgical devices due to the reduced post-operative recovery time and minimal scarring. The most common MIS procedure may be endoscopy, and the most common form of endoscopy is laparoscopy, in which one or more small incisions are formed in the abdomen of a patient and a trocar is inserted through the incision to form a pathway that provides access to the abdominal cavity. The cannula and sealing system of the trocar are used to introduce various instruments and tools into the abdominal cavity, as well as to provide insufflation to elevate the abdominal wall above the organs. The instruments can be used to engage and/or treat tissue in a number of ways to achieve a diagnostic or therapeutic effect. 
     Each surgical tool typically includes an end effector arranged at its distal end. Example end effectors include clamps, graspers, scissors, staplers, suction irrigators, blades (i.e., RF), and needle holders, and are similar to those used in conventional (open) surgery except that the end effector of each tool is separated from its handle by an approximately 12-inch long shaft. A camera or image capture device, such as an endoscope, is also commonly introduced into the abdominal cavity to enable the surgeon to view the surgical field and the operation of the end effectors during operation. The surgeon is able to view the procedure in real-time by means of a visual display in communication with the image capture device. 
     Various robotic systems have recently been developed to assist in MIS procedures. Robotic systems can allow for more intuitive hand movements by maintaining natural eye-hand axis. Robotic systems can also allow for more degrees of freedom in movement by including a “wrist” joint that creates a more natural hand-like articulation and allows for access to hard to reach spaces. The instrument&#39;s end effector can be articulated (moved) using motors and actuators forming part of a computerized motion system. A user (e.g., a surgeon) is able to remotely operate an instrument&#39;s end effector by grasping and manipulating in space one or more controllers that communicate with an instrument driver coupled to the surgical instrument. User inputs are processed by a computer system incorporated into the robotic surgical system and the instrument driver responds by actuating the motors and actuators of the motion system. Moving drive cables, rods, and/or other mechanical mechanisms causes the end effector to articulate to desired positions and configurations. 
     Improvements to robotically-enabled medical systems will provide physicians with the ability to perform endoscopic and laparoscopic procedures more effectively and with improved ease. 
     SUMMARY OF DISCLOSURE 
     Various details of the present disclosure are hereinafter summarized to provide a basic understanding. This summary is not an extensive overview of the disclosure and is neither intended to identify certain elements of the disclosure, nor to delineate the scope thereof. Rather, the primary purpose of this summary is to present some concepts of the disclosure in a simplified form prior to the more detailed description that is presented hereinafter. 
     Embodiments disclosed herein include a robotic surgical tool that includes a handle providing a first drive input and a second drive input, an elongate shaft extendable through the handle and having an end effector arranged at a distal end thereof, and rack extending along a portion of the shaft and operatively coupled to a knife located at the end effector, wherein actuation of the first drive input transitions the rack between a locked configuration, where the rack is locked to the shaft, and a released configuration, where the rack is released from the shaft, wherein actuation of the second drive input with the rack in the locked configuration drives the rack and causes z-axis translation of the shaft through the handle, and wherein actuation of the second drive input with the rack in the released configuration drives the rack relative to the shaft and thereby advances or retracts the knife at the end effector. In a further embodiment, the robotic surgical tool further includes an actuation system housed within the handle and including a shifting mechanism operatively coupled to the first drive input such that actuation of the first drive input transitions the rack between the locked configuration and the released configuration, and a capstan coupled to the second drive input and including a drive gear engageable with a gear train that intermeshes with the rack. In another further embodiment, the robotic surgical tool further includes a rack locking assembly arranged at a proximal end of the shaft and including a latch pivotably coupled to the shaft and engageable with the rack, and a drive cable extending from the shifting mechanism and fixed to the latch, wherein transitioning the actuation system to the second configuration places tension on the drive cable and thereby pivots the latch from a locked position, where the latch secures the rack to the shaft, to a released position, where the latch is released from the rack and allows the rack to move relative to the shaft. In another further embodiment, the latch is spring biased to the locked position. In another further embodiment, a distal end of the drive cable is anchored to the shaft distal to the handle and the drive cable extends through one or more pulleys included in the shifting mechanism, and wherein actuation of the first drive input shifts the shifting mechanism and thereby draws in or pays out a portion of the drive cable. In another further embodiment, the robotic surgical tool further includes a shaft locking mechanism operatively coupled to a third drive input of the handle, wherein actuation of the third drive input causes the shaft locking mechanism to engage and prevent the shaft from moving in z-axis translation. In another further embodiment, the shaft locking mechanism comprises first and second caliper actuating arms pivotably coupled to each other at a first end and engageable with the third drive input at a second end, and wherein actuation of the third drive input forces the first and second caliper actuating arms into lateral binding engagement with the shaft. 
     Embodiments disclosed herein further include a robotic surgical tool that includes a handle providing a first drive input, a second drive input, and a third drive input, an elongate shaft extendable through the handle and having an end effector arranged at a distal end thereof, a rack extending along a portion of the shaft and operatively coupled to a knife located at the end effector, an actuation system housed within the handle and including a shifting mechanism operatively coupled to the first drive input such that actuation of the first drive input transitions the actuation system between a first configuration, where the rack is locked to the shaft, and a second configuration, where the rack is released from the shaft, a first capstan coupled to the second drive input and including a first drive gear engageable with a gear train that intermeshes with the rack when the actuation system is in the first configuration, and a second capstan coupled to the third drive input and including a second drive gear engageable with the gear train when the actuation system is in the second configuration, wherein actuation of the second drive input with the actuation system in the first configuration drives the rack and causes z-axis translation of the shaft through the handle, and wherein actuation of the third drive input with the actuation system in the second configuration drives the rack relative to the shaft and thereby advances or retracts the knife at the end effector. In a further embodiment, the robotic surgical tool further includes a rack locking assembly arranged at a proximal end of the shaft and including a latch pivotably coupled to the shaft and engageable with the rack, and a drive cable extending from the shifting mechanism and fixed to the latch, wherein transitioning the actuation system to the second configuration places tension on the drive cable and thereby pivots the latch from a locked position, where the latch secures the rack to the shaft, to a released position, where the latch is released from the rack and allows the rack to move relative to the shaft. In another further embodiment, the latch is spring biased to the locked position. In another further embodiment, a distal end of the drive cable is anchored to the shaft distal to the handle and the drive cable extends through one or more pulleys included in the shifting mechanism, and wherein actuation of the first drive input shifts the shifting mechanism and thereby draws in or pays out a portion of the drive cable. In another further embodiment, the robotic surgical tool further includes a shaft locking mechanism operatively coupled to a fourth drive input of the handle, wherein actuation of the fourth drive input causes the shaft locking mechanism to engage and prevent the shaft from moving in z-axis translation. In another further embodiment, the shaft locking mechanism comprises first and second caliper actuating arms pivotably coupled to each other at a first end and engageable with the fourth drive input at a second end, and wherein actuation of the fourth drive input forces the first and second caliper actuating arms into lateral binding engagement with the shaft. In another further embodiment, the robotic surgical tool further includes a first driven gear mounted to an axle and engageable with the first drive gear, a second driven gear mounted to the axle and engageable with the second drive gear, and a clutch interposing the first and second drive gears and laterally movable with the shifting mechanism between the first and second driven gears, wherein the clutch engages a first clutch interface at the first driven gear when the actuation system is in the first configuration and thereby allows the first drive gear to drive the rack via the gear train, and wherein the clutch engages a second clutch interface at the second driven gear when the actuation system is in the second configuration and thereby allows the second drive gear to drive the rack via the gear train. In another further embodiment, the clutch includes a spool engageable with a pin provided by the shifting mechanism, and wherein transitioning the actuation system between the first and second configurations moves the clutch between the first and second clutch interfaces via the engaged spool and pin. 
     Embodiments disclosed herein further include a method of operating a robotic surgical tool, the method including arranging a robotic surgical tool adjacent a patient, the robotic surgical tool including an elongate shaft extending through a handle and having an end effector arranged at a distal end thereof, the handle providing a first drive input and a second drive input, a rack extending along a portion of the shaft and operatively coupled to a knife located at the end effector, and an actuation system housed within the handle and including a shifting mechanism operatively coupled to the first drive input, a capstan coupled to the second drive input and including a drive gear engageable with a gear train that intermeshes with the rack. The method further includes actuating the first drive input and thereby transitioning the actuation system to a first configuration where the rack is locked to the shaft, actuating the second drive input with the actuation system in the first configuration and thereby rotating the capstan and causing z-axis translation of the shaft through the handle, actuating the first drive input and thereby transitioning the actuation system to a second configuration where the rack is released from the shaft, and driving the rack relative to the shaft with the actuation system in the second configuration and thereby advancing or retracting the knife at the end effector. In a further embodiment, driving the rack relative to the shaft comprises actuating the second drive input with the actuation system in the second configuration and thereby driving the rack relative to the shaft to advance or retract the knife at the end effector. In another further embodiment, the robotic surgical tool further includes a rack locking assembly arranged at a proximal end of the shaft and including a latch pivotably coupled to the shaft and engageable with the rack, and a drive cable extending from the shifting mechanism and fixed to the latch, and wherein actuating the first drive input and thereby transitioning the actuation system to the second configuration comprises shifting the shifting mechanism and thereby placing tension on the drive cable, and pivoting the latch from a locked position, where the latch secures the rack to the shaft, to a released position, where the latch is released from the rack and allows the rack to move relative to the shaft. In another further embodiment, the robotic surgical tool further a shaft locking mechanism operatively coupled to a third drive input of the handle, the method further comprising actuating the third drive input when the actuation system is in the second configuration and thereby engaging the shaft with the shaft locking mechanism and preventing the shaft from moving in z-axis translation, and actuating the third drive input when the actuation system is in the first configuration and thereby disengaging the shaft with the shaft locking mechanism and allowing the shaft to move in z-axis translation. In another further embodiment, the capstan is a first capstan, the drive gear is a first drive gear, and the robotic surgical tool further includes a third drive input provided by the handle, and a second capstan coupled to the third drive input and including a second drive gear engageable with the gear train when the actuation system is in the second configuration, and wherein driving the rack relative to the shaft with the actuation system in the second configuration comprises actuating the third drive input with the actuation system in the second configuration and thereby driving the rack relative to the shaft to advance or retract the knife at the end effector. In another further embodiment, the robotic surgical tool further includes a rack locking assembly arranged at a proximal end of the shaft and including a latch pivotably coupled to the shaft and engageable with the rack, and a drive cable extending from the shifting mechanism and fixed to the latch, and wherein actuating the first drive input and thereby transitioning the actuation system to the second configuration comprises shifting the shifting mechanism and thereby placing tension on the drive cable, and pivoting the latch from a locked position, where the latch secures the rack to the shaft, to a released position, where the latch is released from the rack and allows the rack to move relative to the shaft. In another further embodiment, the robotic surgical tool further includes a first driven gear mounted to an axle and engageable with the first drive gear, a second driven gear mounted to the axle and engageable with the second drive gear, and a clutch interposing the first and second drive gears and laterally movable with the shifting mechanism between the first and second driven gears, and wherein the method further comprises engaging the clutch at a first clutch interface at the first driven gear when the actuation system is in the first configuration and thereby allowing the first drive gear to drive the rack via the gear train, and engaging the clutch at a second clutch interface at the second driven gear when the actuation system is in the second configuration and thereby allowing the second drive gear to drive the rack via the gear train. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosed aspects will hereinafter be described in conjunction with the appended drawings, provided to illustrate and not to limit the disclosed aspects, wherein like designations denote like elements. 
         FIG. 1  illustrates an embodiment of a cart-based robotic system arranged for diagnostic and/or therapeutic bronchoscopy procedure(s). 
         FIG. 2  depicts further aspects of the robotic system of  FIG. 1 . 
         FIG. 3A  illustrates an embodiment of the robotic system of  FIG. 1  arranged for ureteroscopy. 
         FIG. 3B  illustrates an embodiment of the robotic system of  FIG. 1  arranged for a vascular procedure. 
         FIG. 4  illustrates an embodiment of a table-based robotic system arranged for a bronchoscopy procedure. 
         FIG. 5  provides an alternative view of the robotic system of  FIG. 4 . 
         FIG. 6  illustrates an example system configured to stow robotic arm(s). 
         FIG. 7A  illustrates an embodiment of a table-based robotic system configured for a ureteroscopy procedure. 
         FIG. 7B  illustrates an embodiment of a table-based robotic system configured for a laparoscopic procedure. 
         FIG. 7C  illustrates an embodiment of the table-based robotic system of 
         FIGS. 4-7B  with pitch or tilt adjustment. 
         FIG. 8  provides a detailed illustration of the interface between the table and the column of the table-based robotic system of  FIGS. 4-7 . 
         FIG. 9A  illustrates an alternative embodiment of a table-based robotic system. 
         FIG. 9B  illustrates an end view of the table-based robotic system of  FIG. 9A . 
         FIG. 9C  illustrates an end view of a table-based robotic system with robotic arms attached thereto. 
         FIG. 10  illustrates an exemplary instrument driver. 
         FIG. 11  illustrates an exemplary medical instrument with a paired instrument driver. 
         FIG. 12  illustrates an alternative design for an instrument driver and instrument where the axes of the drive units are parallel to the axis of the elongated shaft of the instrument. 
         FIG. 13  illustrates an instrument having an instrument-based insertion architecture. 
         FIG. 14  illustrates an exemplary controller. 
         FIG. 15  depicts a block diagram illustrating a localization system that estimates a location of one or more elements of the robotic systems of  FIGS. 1-7C , such as the location of the instrument of  FIGS. 11-13 , in accordance to an example embodiment. 
         FIG. 16  is an isometric side view of an example surgical tool that may incorporate some or all of the principles of the present disclosure. 
         FIG. 17  depicts separated isometric end views of the instrument driver and the surgical tool of  FIG. 16 . 
         FIGS. 18A and 18B  are enlarged isometric views of the handle of  FIGS. 16-17  from different side perspectives and depicting an example actuation system, according to one or more embodiments. 
         FIG. 19  is an enlarged front view of an example rack locking device, according to one or more embodiments of the disclosure. 
         FIG. 20  is an isometric side view of one example of the rack of  FIGS. 18A and 19  operatively coupled to a knife, according to one or more embodiments. 
         FIG. 21  is an enlarged cross-sectional side view of the end effector of  FIG. 16 , according to one or more embodiments. 
         FIG. 22  is another isometric view of the handle and the actuation system of  FIGS. 18A-18B , according to one or more embodiments. 
         FIG. 23  depicts interconnected logic diagrams for operating the surgical tool  1600  of  FIGS. 16-17 . 
         FIG. 24  is an enlarged view of the end effector and the wrist of  FIGS. 16-17 , according to one or more embodiments. 
         FIG. 25  is an enlarged side view of another embodiment of the handle of  FIGS. 16-17 , according to one or more embodiments of the present disclosure. 
         FIG. 26  is an enlarged side view of another embodiment of the handle of  FIGS. 16-17 , according to one or more additional embodiments of the present disclosure. 
         FIG. 27  is an enlarged side schematic view of another embodiment of the handle of  FIGS. 16-17 , according to one or more additional embodiments of the present disclosure. 
         FIG. 28  is a schematic side view of an example of the first actuation system of  FIG. 27 , according to one or more embodiments. 
         FIG. 29  is a cross-sectional end view of a portion of the shaft and the first drive belt of  FIG. 27 , according to one or more embodiments. 
         FIG. 30  is a cross-sectional end view of another portion of the shaft and the first drive belt of  FIG. 27 , according to one or more additional embodiments. 
         FIG. 31  is an enlarged side schematic view of another embodiment of the handle of  FIGS. 16-17 , according to one or more additional embodiments of the present disclosure. 
         FIGS. 32A and 32B  are isometric side and top views, respectively, of an example seal system that may be incorporated into one or more of the presently disclosed embodiments. 
         FIG. 33  is a partial cross-sectional side view of an example handle, according to one or more embodiments. 
         FIGS. 34A and 34B  are isometric and top views, respectively, of an example of the seal cartridge of  FIG. 33 , according to one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     1. Overview. 
     Aspects of the present disclosure may be integrated into a robotically-enabled medical system capable of performing a variety of medical procedures, including both minimally invasive (e.g., laparoscopy) and non-invasive (e.g., endoscopy) procedures. Among endoscopy procedures, the system may be capable of performing bronchoscopy, ureteroscopy, gastroscopy, etc. 
     In addition to performing the breadth of procedures, the system may provide additional benefits, such as enhanced imaging and guidance, to assist the physician. Additionally, the system may provide the physician with the ability to perform the procedure from an ergonomic position without the need for awkward arm motions and positions. Still further, the system may provide the physician with the ability to perform the procedure with improved ease of use such that one or more of the instruments of the system can be controlled by a single user. 
     Various embodiments will be described below in conjunction with the drawings for purposes of illustration. It should be appreciated that many other implementations of the disclosed concepts are possible, and various advantages can be achieved with the disclosed implementations. Headings are included herein for reference and to aid in locating various sections. These headings are not intended to limit the scope of the concepts described with respect thereto, as such concepts may have applicability throughout the entire specification. 
     A. Robotic System—Cart. 
     The robotically-enabled medical system may be configured in a variety of ways depending on the particular procedure.  FIG. 1  illustrates an embodiment of a cart-based robotically-enabled system  100  arranged for a diagnostic and/or therapeutic bronchoscopy procedure. For a bronchoscopy procedure, the robotic system  100  may include a cart  102  having one or more robotic arms  104  (three shown) to deliver a medical instrument (alternately referred to as a “surgical tool”), such as a steerable endoscope  106  (e.g., a procedure-specific bronchoscope for bronchoscopy), to a natural orifice access point (i.e., the mouth of the patient) to deliver diagnostic and/or therapeutic tools. As shown, the cart  102  may be positioned proximate to the patient&#39;s upper torso in order to provide access to the access point. Similarly, the robotic arms  104  may be actuated to position the bronchoscope relative to the access point. The arrangement in  FIG. 1  may also be utilized when performing a gastro-intestinal (GI) procedure with a gastroscope, a specialized endoscope for GI procedures. 
     Once the cart  102  is properly positioned adjacent the patient, the robotic arms  104  are operated to insert the steerable endoscope  106  into the patient robotically, manually, or a combination thereof. The steerable endoscope  106  may comprise at least two telescoping parts, such as an inner leader portion and an outer sheath portion, where each portion is coupled to a separate instrument driver of a set of instrument drivers  108 . As illustrated, each instrument driver  108  is coupled to the distal end of a corresponding one of the robotic arms  104 . This linear arrangement of the instrument drivers  108 , which facilitates coaxially aligning the leader portion with the sheath portion, creates a “virtual rail”  110  that may be repositioned in space by manipulating the robotic arms  104  into different angles and/or positions. Translation of the instrument drivers  108  along the virtual rail  110  telescopes the inner leader portion relative to the outer sheath portion, thus effectively advancing or retracting the endoscope  106  relative to the patient. 
     As illustrated, the virtual rail  110  (and other virtual rails described herein) is depicted in the drawings using dashed lines, thus not constituting any physical structure of the system  100 . The angle of the virtual rail  110  may be adjusted, translated, and pivoted based on clinical application or physician preference. For example, in bronchoscopy, the angle and position of the virtual rail  110  as shown represents a compromise between providing physician access to the endoscope  106  while minimizing friction that results from bending the endoscope  106  into the patient&#39;s mouth. 
     After insertion into the patient&#39;s mouth, the endoscope  106  may be directed down the patient&#39;s trachea and lungs using precise commands from the robotic system  100  until reaching a target destination or operative site. In order to enhance navigation through the patient&#39;s lung network and/or reach the desired target, the endoscope  106  may be manipulated to telescopically extend the inner leader portion from the outer sheath portion to obtain enhanced articulation and greater bend radius. The use of separate instrument drivers  108  also allows the leader portion and sheath portion to be driven independent of each other. 
     For example, the endoscope  106  may be directed to deliver a biopsy needle to a target, such as, for example, a lesion or nodule within the lungs of a patient. The needle may be deployed down a working channel that runs the length of the endoscope  106  to obtain a tissue sample to be analyzed by a pathologist. Depending on the pathology results, additional tools may be deployed down the working channel of the endoscope for additional biopsies. After identifying a tissue sample to be malignant, the endoscope  106  may endoscopically deliver tools to resect the potentially cancerous tissue. In some instances, diagnostic and therapeutic treatments can be delivered in separate procedures. In those circumstances, the endoscope  106  may also be used to deliver a fiducial marker to “mark” the location of a target nodule as well. In other instances, diagnostic and therapeutic treatments may be delivered during the same procedure. 
     The system  100  may also include a movable tower  112 , which may be connected via support cables to the cart  102  to provide support for controls, electronics, fluidics, optics, sensors, and/or power to the cart  102 . Placing such functionality in the tower  112  allows for a smaller form factor cart  102  that may be more easily adjusted and/or re-positioned by an operating physician and his/her staff. Additionally, the division of functionality between the cart/table and the support tower  112  reduces operating room clutter and facilitates improving clinical workflow. While the cart  102  may be positioned close to the patient, the tower  112  may alternatively be stowed in a remote location to stay out of the way during a procedure. 
     In support of the robotic systems described above, the tower  112  may include component(s) of a computer-based control system that stores computer program instructions, for example, within a non-transitory computer-readable storage medium such as a persistent magnetic storage drive, solid state drive, etc. The execution of those instructions, whether the execution occurs in the tower  112  or the cart  102 , may control the entire system or sub-system(s) thereof. For example, when executed by a processor of the computer system, the instructions may cause the components of the robotics system to actuate the relevant carriages and arm mounts, actuate the robotics arms, and control the medical instruments. For example, in response to receiving the control signal, motors in the joints of the robotic arms  104  may position the arms into a certain posture or angular orientation. 
     The tower  112  may also include one or more of a pump, flow meter, valve control, and/or fluid access in order to provide controlled irrigation and aspiration capabilities to the system  100  that may be deployed through the endoscope  106 . These components may also be controlled using the computer system of the tower  112 . In some embodiments, irrigation and aspiration capabilities may be delivered directly to the endoscope  106  through separate cable(s). 
     The tower  112  may include a voltage and surge protector designed to provide filtered and protected electrical power to the cart  102 , thereby avoiding placement of a power transformer and other auxiliary power components in the cart  102 , resulting in a smaller, more moveable cart  102 . 
     The tower  112  may also include support equipment for sensors deployed throughout the robotic system  100 . For example, the tower  112  may include opto-electronics equipment for detecting, receiving, and processing data received from optical sensors or cameras throughout the robotic system  100 . In combination with the control system, such opto-electronics equipment may be used to generate real-time images for display in any number of consoles deployed throughout the system, including in the tower  112 . Similarly, the tower  112  may also include an electronic subsystem for receiving and processing signals received from deployed electromagnetic (EM) sensors. The tower  112  may also be used to house and position an EM field generator for detection by EM sensors in or on the medical instrument. 
     The tower  112  may also include a console  114  in addition to other consoles available in the rest of the system, e.g., a console mounted to the cart  102 . The console  114  may include a user interface and a display screen (e.g., a touchscreen) for the physician operator. Consoles in the system  100  are generally designed to provide both robotic controls as well as pre-operative and real-time information of the procedure, such as navigational and localization information of the endoscope  106 . When the console  114  is not the only console available to the physician, it may be used by a second operator, such as a nurse, to monitor the health or vitals of the patient and the operation of system, as well as provide procedure-specific data, such as navigational and localization information. In other embodiments, the console  114  may be housed in a body separate from the tower  112 . 
     The tower  112  may be coupled to the cart  102  and endoscope  106  through one or more cables  116  connections. In some embodiments, support functionality from the tower  112  may be provided through a single cable  116  extending to the cart  102 , thus simplifying and de-cluttering the operating room. In other embodiments, specific functionality may be coupled in separate cabling and connections. For example, while power may be provided through a single power cable to the cart  102 , support for controls, optics, fluidics, and/or navigation may be provided through one or more separate cables. 
       FIG. 2  provides a detailed illustration of an embodiment of the cart  102  from the cart-based robotically-enabled system  100  of  FIG. 1 . The cart  102  generally includes an elongated support structure  202  (also referred to as a “column”), a cart base  204 , and a console  206  at the top of the column  202 . The column  202  may include one or more carriages, such as a carriage  208  (alternatively “arm support”) for supporting the deployment of the robotic arms  104 . The carriage  208  may include individually configurable arm mounts that rotate along a perpendicular axis to adjust the base  214  of the robotic arms  104  for better positioning relative to the patient. The carriage  208  also includes a carriage interface  210  that allows the carriage  208  to vertically translate along the column  202 . 
     The carriage interface  210  is connected to the column  202  through slots, such as slot  212 , that are positioned on opposite sides of the column  202  to guide the vertical translation of the carriage  208 . The slot  212  contains a vertical translation interface to position and hold the carriage  208  at various vertical heights relative to the cart base  204 . Vertical translation of the carriage  208  allows the cart  102  to adjust the reach of the robotic arms  104  to meet a variety of table heights, patient sizes, and physician preferences. Similarly, the individually configurable arm mounts on the carriage  208  allow a base  214  of the robotic arms  104  to be angled in a variety of configurations. 
     In some embodiments, the slot  212  may be supplemented with slot covers (not shown) that are flush and parallel to the slot surface to prevent dirt and fluid ingress into the internal chambers of the column  202  and the vertical translation interface as the carriage  208  vertically translates. The slot covers may be deployed through pairs of spring spools positioned near the vertical top and bottom of the slot  212 . The covers are coiled within the spools until deployed to extend and retract from their coiled state as the carriage  208  vertically translates up and down. The spring-loading of the spools provides force to retract the cover into a spool when carriage  208  translates towards the spool, while also maintaining a tight seal when the carriage  208  translates away from the spool. The covers may be connected to the carriage  208  using, for example, brackets in the carriage interface  210  to ensure proper extension and retraction of the cover as the carriage  208  translates. 
     The column  202  may internally comprise mechanisms, such as gears and motors, which are designed to use a vertically aligned lead screw to translate the carriage  208  in a mechanized fashion in response to control signals generated in response to user inputs, e.g., inputs from the console  206 . 
     The robotic arms  104  may generally comprise robotic arm bases  214  and end effectors  216  (three shown), separated by a series of linkages  218  connected by a corresponding series of joints  220 , each joint  220  including an independent actuator, and each actuator including an independently controllable motor. Each independently controllable joint  220  represents an independent degree of freedom available to the corresponding robotic arm  104 . In the illustrated embodiment, each arm  104  has seven joints  220 , thus providing seven degrees of freedom. A multitude of joints  220  result in a multitude of degrees of freedom, allowing for “redundant” degrees of freedom. Redundant degrees of freedom allow the robotic arms  104  to position their respective end effectors  216  at a specific position, orientation, and trajectory in space using different linkage positions and joint angles. This allows for the system  100  to position and direct a medical instrument from a desired point in space while allowing the physician to move the arm joints  220  into a clinically advantageous position away from the patient to create greater access, while avoiding arm collisions. 
     The cart base  204  balances the weight of the column  202 , the carriage  208 , and the arms  104  over the floor. Accordingly, the cart base  204  houses heavier components, such as electronics, motors, power supply, as well as components that either enable movement and/or immobilize the cart. For example, the cart base  204  includes rolling casters  222  that allow for the cart to easily move around the room prior to a procedure. After reaching an appropriate position, the casters  222  may be immobilized using wheel locks to hold the cart  102  in place during the procedure. 
     Positioned at the vertical end of the column  202 , the console  206  allows for both a user interface for receiving user input and a display screen (or a dual-purpose device such as, for example, a touchscreen  224 ) to provide the physician user with both pre-operative and intra-operative data. Potential pre-operative data on the touchscreen  224  may include pre-operative plans, navigation and mapping data derived from pre-operative computerized tomography (CT) scans, and/or notes from pre-operative patient interviews. Intra-operative data on the touchscreen  224  may include optical information provided from the tool, sensor and coordinate information from sensors, as well as vital patient statistics, such as respiration, heart rate, and/or pulse. The console  206  may be positioned and tilted to allow a physician to access the console from the side of the column  202  opposite carriage  208 . From this position, the physician may view the console  206 , the robotic arms  104 , and the patient while operating the console  206  from behind the cart  102 . As shown, the console  206  also includes a handle  226  to assist with maneuvering and stabilizing cart  102 . 
       FIG. 3A  illustrates an embodiment of the system  100  of  FIG. 1  arranged for ureteroscopy. In a ureteroscopic procedure, the cart  102  may be positioned to deliver a ureteroscope  302 , a procedure-specific endoscope designed to traverse a patient&#39;s urethra and ureter, to the lower abdominal area of the patient. In ureteroscopy, it may be desirable for the ureteroscope  302  to be directly aligned with the patient&#39;s urethra to reduce friction and forces on the sensitive anatomy. As shown, the cart  102  may be aligned at the foot of the table to allow the robotic arms  104  to position the ureteroscope  302  for direct linear access to the patient&#39;s urethra. From the foot of the table, the robotic arms  104  may insert the ureteroscope  302  along a virtual rail  304  directly into the patient&#39;s lower abdomen through the urethra. 
     After insertion into the urethra, using similar control techniques as in bronchoscopy, the ureteroscope  302  may be navigated into the bladder, ureters, and/or kidneys for diagnostic and/or therapeutic applications. For example, the ureteroscope  302  may be directed into the ureter and kidneys to break up kidney stone build-up using a laser or ultrasonic lithotripsy device deployed down a working channel of the ureteroscope  302 . After lithotripsy is complete, the resulting stone fragments may be removed using baskets deployed down the working channel of the ureteroscope  302 . 
       FIG. 3B  illustrates another embodiment of the system  100  of  FIG. 1  arranged for a vascular procedure. In a vascular procedure, the system  100  may be configured such that the cart  102  may deliver a medical instrument  306 , such as a steerable catheter, to an access point in the femoral artery in the patient&#39;s leg. The femoral artery presents both a larger diameter for navigation as well as a relatively less circuitous and tortuous path to the patient&#39;s heart, which simplifies navigation. As in a ureteroscopic procedure, the cart  102  may be positioned towards the patient&#39;s legs and lower abdomen to allow the robotic arms  104  to provide a virtual rail  308  with direct linear access to the femoral artery access point in the patient&#39;s thigh/hip region. After insertion into the artery, the medical instrument  306  may be directed and advanced by translating the instrument drivers  108 . Alternatively, the cart  102  may be positioned around the patient&#39;s upper abdomen in order to reach alternative vascular access points, such as, for example, the carotid and brachial arteries near the patient&#39;s shoulder and wrist. 
     B. Robotic System—Table. 
     Embodiments of the robotically-enabled medical system may also incorporate the patient&#39;s table. Incorporation of the table reduces the amount of capital equipment within the operating room by removing the cart, which allows greater access to the patient.  FIG. 4  illustrates an embodiment of such a robotically-enabled system  400  arranged for a bronchoscopy procedure. As illustrated, the system  400  includes a support structure or column  402  for supporting platform  404  (shown as a “table” or “bed”) over the floor. Much like in the cart-based systems, the end effectors of the robotic arms  406  of the system  400  comprise instrument drivers  408  that are designed to manipulate an elongated medical instrument, such as a bronchoscope  410 , through or along a virtual rail  412  formed from the linear alignment of the instrument drivers  408 . In practice, a C-arm for providing fluoroscopic imaging may be positioned over the patient&#39;s upper abdominal area by placing the emitter and detector around the table  404 . 
       FIG. 5  provides an alternative view of the system  400  without the patient and medical instrument for discussion purposes. As shown, the column  402  may include one or more carriages  502  shown as ring-shaped in the system  400 , from which the one or more robotic arms  406  may be based. The carriages  502  may translate along a vertical column interface  504  that runs the length (height) of the column  402  to provide different vantage points from which the robotic arms  406  may be positioned to reach the patient. The carriage(s)  502  may rotate around the column  402  using a mechanical motor positioned within the column  402  to allow the robotic arms  406  to have access to multiples sides of the table  404 , such as, for example, both sides of the patient. In embodiments with multiple carriages  502 , the carriages  502  may be individually positioned on the column  402  and may translate and/or rotate independent of the other carriages  502 . While carriages  502  need not surround the column  402  or even be circular, the ring-shape as shown facilitates rotation of the carriages  502  around the column  402  while maintaining structural balance. Rotation and translation of the carriages  502  allows the system  400  to align medical instruments, such as endoscopes and laparoscopes, into different access points on the patient. 
     In other embodiments (discussed in greater detail below with respect to  FIG. 9A ), the system  400  can include a patient table or bed with adjustable arm supports in the form of bars or rails extending alongside it. One or more robotic arms  406  (e.g., via a shoulder with an elbow joint) can be attached to the adjustable arm supports, which can be vertically adjusted. By providing vertical adjustment, the robotic arms  406  are advantageously capable of being stowed compactly beneath the patient table or bed, and subsequently raised during a procedure. 
     The arms  406  may be mounted on the carriages  502  through a set of arm mounts  506  comprising a series of joints that may individually rotate and/or telescopically extend to provide additional configurability to the robotic arms  406 . Additionally, the arm mounts  506  may be positioned on the carriages  502  such that when the carriages  502  are appropriately rotated, the arm mounts  506  may be positioned on either the same side of the table  404  (as shown in  FIG. 5 ), on opposite sides of table  404  (as shown in  FIG. 7B ), or on adjacent sides of the table  404  (not shown). 
     The column  402  structurally provides support for the table  404 , and a path for vertical translation of the carriages  502 . Internally, the column  402  may be equipped with lead screws for guiding vertical translation of the carriages, and motors to mechanize the translation of said carriages based the lead screws. The column  402  may also convey power and control signals to the carriage  502  and robotic arms  406  mounted thereon. 
     A table base  508  serves a similar function as the cart base  204  of the cart  102  shown in  FIG. 2 , housing heavier components to balance the table/bed  404 , the column  402 , the carriages  502 , and the robotic arms  406 . The table base  508  may also incorporate rigid casters to provide stability during procedures. Deployed from the bottom of the table base  508 , the casters may extend in opposite directions on both sides of the base  508  and retract when the system  400  needs to be moved. 
     In some embodiments, the system  400  may also include a tower (not shown) that divides the functionality of system  400  between table and tower to reduce the form factor and bulk of the table  404 . As in earlier disclosed embodiments, the tower may provide a variety of support functionalities to the table  404 , such as processing, computing, and control capabilities, power, fluidics, and/or optical and sensor processing. The tower may also be movable to be positioned away from the patient to improve physician access and de-clutter the operating room. Additionally, placing components in the tower allows for more storage space in the table base  508  for potential stowage of the robotic arms  406 . The tower may also include a master controller or console that provides both a user interface for user input, such as keyboard and/or pendant, as well as a display screen (or touchscreen) for pre-operative and intra-operative information, such as real-time imaging, navigation, and tracking information. In some embodiments, the tower may also contain holders for gas tanks to be used for insufflation. 
     In some embodiments, a table base may stow and store the robotic arms when not in use.  FIG. 6  illustrates an embodiment of the system  400  that is configured to stow robotic arms in an embodiment of the table-based system. In the system  400 , one or more carriages  602  (one shown) may be vertically translated into a base  604  to stow one or more robotic arms  606 , one or more arm mounts  608 , and the carriages  602  within the base  604 . Base covers  610  may be translated and retracted open to deploy the carriages  602 , the arm mounts  608 , and the arms  606  around the column  612 , and closed to stow and protect them when not in use. The base covers  610  may be sealed with a membrane  614  along the edges of its opening to prevent dirt and fluid ingress when closed. 
       FIG. 7A  illustrates an embodiment of the robotically-enabled table-based system  400  configured for a ureteroscopy procedure. In ureteroscopy, the table  404  may include a swivel portion  702  for positioning a patient off-angle from the column  402  and the table base  508 . The swivel portion  702  may rotate or pivot around a pivot point (e.g., located below the patient&#39;s head) in order to position the bottom portion of the swivel portion  702  away from the column  402 . For example, the pivoting of the swivel portion  702  allows a C-arm (not shown) to be positioned over the patient&#39;s lower abdomen without competing for space with the column (not shown) below table  404 . By rotating the carriage (not shown) around the column  402 , the robotic arms  406  may directly insert a ureteroscope  704  along a virtual rail  706  into the patient&#39;s groin area to reach the urethra. In ureteroscopy, stirrups  708  may also be fixed to the swivel portion  702  of the table  404  to support the position of the patient&#39;s legs during the procedure and allow clear access to the patient&#39;s groin area. 
       FIG. 7B  illustrates an embodiment of the system  400  configured for a laparoscopic procedure. In a laparoscopic procedure, through small incision(s) in the patient&#39;s abdominal wall, minimally invasive instruments may be inserted into the patient&#39;s anatomy. In some embodiments, the minimally invasive instruments comprise an elongated rigid member, such as a shaft, which is used to access anatomy within the patient. After inflation of the patient&#39;s abdominal cavity, the instruments may be directed to perform surgical or medical tasks, such as grasping, cutting, ablating, suturing, etc. In some embodiments, the instruments can comprise a scope, such as a laparoscope. As shown in  FIG. 7B , the carriages  502  of the system  400  may be rotated and vertically adjusted to position pairs of the robotic arms  406  on opposite sides of the table  404 , such that an instrument  710  may be positioned using the arm mounts  506  to be passed through minimal incisions on both sides of the patient to reach his/her abdominal cavity. 
     To accommodate laparoscopic procedures, the system  400  may also tilt the platform to a desired angle.  FIG. 7C  illustrates an embodiment of the system  400  with pitch or tilt adjustment. As shown in  FIG. 7C , the system  400  may accommodate tilt of the table  404  to position one portion of the table  404  at a greater distance from the floor than the other. Additionally, the arm mounts  506  may rotate to match the tilt such that the arms  406  maintain the same planar relationship with table  404 . To accommodate steeper angles, the column  402  may also include telescoping portions  712  that allow vertical extension of the column  402  to keep the table  404  from touching the floor or colliding with the base  508 . 
       FIG. 8  provides a detailed illustration of the interface between the table  404  and the column  402 . Pitch rotation mechanism  802  may be configured to alter the pitch angle of the table  404  relative to the column  402  in multiple degrees of freedom. The pitch rotation mechanism  802  may be enabled by the positioning of orthogonal axes A and B at the column-table interface, each axis actuated by a separate motor  804   a  and  804   b  responsive to an electrical pitch angle command. Rotation along one screw  806   a  would enable tilt adjustments in one axis A, while rotation along another screw  806   b  would enable tilt adjustments along the other axis B. In some embodiments, a ball joint can be used to alter the pitch angle of the table  404  relative to the column  402  in multiple degrees of freedom. 
     For example, pitch adjustments are particularly useful when trying to position the table in a Trendelenburg position, i.e., position the patient&#39;s lower abdomen at a higher position from the floor than the patient&#39;s lower abdomen, for lower abdominal surgery. The Trendelenburg position causes the patient&#39;s internal organs to slide towards his/her upper abdomen through the force of gravity, clearing out the abdominal cavity for minimally invasive tools to enter and perform lower abdominal surgical or medical procedures, such as laparoscopic prostatectomy. 
       FIGS. 9A and 9B  illustrate isometric and end views, respectively, of an alternative embodiment of a table-based surgical robotics system  900 . The surgical robotics system  900  includes one or more adjustable arm supports  902  that can be configured to support one or more robotic arms (see, for example,  FIG. 9C ) relative to a table  904 . In the illustrated embodiment, a single adjustable arm support  902  is shown, though an additional arm support can be provided on an opposite side of the table  904 . The adjustable arm support  902  can be configured so that it can move relative to the table  904  to adjust and/or vary the position of the adjustable arm support  902  and/or any robotic arms mounted thereto relative to the table  904 . For example, the adjustable arm support  902  may be adjusted in one or more degrees of freedom relative to the table  904 . The adjustable arm support  902  provides high versatility to the system  900 , including the ability to easily stow the one or more adjustable arm supports  902  and any robotics arms attached thereto beneath the table  904 . The adjustable arm support  902  can be elevated from the stowed position to a position below an upper surface of the table  904 . In other embodiments, the adjustable arm support  902  can be elevated from the stowed position to a position above an upper surface of the table  904 . 
     The adjustable arm support  902  can provide several degrees of freedom, including lift, lateral translation, tilt, etc. In the illustrated embodiment of  FIGS. 9A and 9B , the arm support  902  is configured with four degrees of freedom, which are illustrated with arrows in  FIG. 9A . A first degree of freedom allows for adjustment of the adjustable arm support  902  in the z-direction (“Z-lift”). For example, the adjustable arm support  902  can include a carriage  906  configured to move up or down along or relative to a column  908  supporting the table  904 . A second degree of freedom can allow the adjustable arm support  902  to tilt. For example, the adjustable arm support  902  can include a rotary joint, which can allow the adjustable arm support  902  to be aligned with the bed in a Trendelenburg position. A third degree of freedom can allow the adjustable arm support  902  to “pivot up,” which can be used to adjust a distance between a side of the table  904  and the adjustable arm support  902 . A fourth degree of freedom can permit translation of the adjustable arm support  902  along a longitudinal length of the table. 
     The surgical robotics system  900  in  FIGS. 9A and 9B  can comprise a table  904  supported by a column  908  that is mounted to a base  910 . The base  910  and the column  908  support the table  904  relative to a support surface. A floor axis  912  and a support axis  914  are shown in  FIG. 9B . 
     The adjustable arm support  902  can be mounted to the column  908 . In other embodiments, the arm support  902  can be mounted to the table  904  or the base  910 . The adjustable arm support  902  can include a carriage  906 , a bar or rail connector  916  and a bar or rail  918 . In some embodiments, one or more robotic arms mounted to the rail  918  can translate and move relative to one another. 
     The carriage  906  can be attached to the column  908  by a first joint  920 , which allows the carriage  906  to move relative to the column  908  (e.g., such as up and down a first or vertical axis  922 ). The first joint  920  can provide the first degree of freedom (“Z-lift”) to the adjustable arm support  902 . The adjustable arm support  902  can include a second joint  924 , which provides the second degree of freedom (tilt) for the adjustable arm support  902 . The adjustable arm support  902  can include a third joint  926 , which can provide the third degree of freedom (“pivot up”) for the adjustable arm support  902 . An additional joint  928  (shown in  FIG. 9B ) can be provided that mechanically constrains the third joint  926  to maintain an orientation of the rail  918  as the rail connector  916  is rotated about a third axis  930 . The adjustable arm support  902  can include a fourth joint  932 , which can provide a fourth degree of freedom (translation) for the adjustable arm support  902  along a fourth axis  934 . 
       FIG. 9C  illustrates an end view of the surgical robotics system  900  with two adjustable arm supports  902   a  and  902   b  mounted on opposite sides of the table  904 . A first robotic arm  936   a  is attached to the first bar or rail  918   a  of the first adjustable arm support  902   a.  The first robotic arm  936   a  includes a base  938   a  attached to the first rail  918   a.  The distal end of the first robotic arm  936   a  includes an instrument drive mechanism or input  940   a  that can attach to one or more robotic medical instruments or tools. Similarly, the second robotic arm  936   b  includes a base  938   a  attached to the second rail  918   b.  The distal end of the second robotic arm  936   b  includes an instrument drive mechanism or input  940   b  configured to attach to one or more robotic medical instruments or tools. 
     In some embodiments, one or more of the robotic arms  936   a,b  comprises an arm with seven or more degrees of freedom. In some embodiments, one or more of the robotic arms  936   a,b  can include eight degrees of freedom, including an insertion axis (1-degree of freedom including insertion), a wrist (3-degrees of freedom including wrist pitch, yaw and roll), an elbow (1-degree of freedom including elbow pitch), a shoulder (2-degrees of freedom including shoulder pitch and yaw), and base  938   a,b  (1-degree of freedom including translation). In some embodiments, the insertion degree of freedom can be provided by the robotic arm  936   a,b,  while in other embodiments, the instrument itself provides insertion via an instrument-based insertion architecture. 
     C. Instrument Driver &amp; Interface. 
     The end effectors of a system&#39;s robotic arms comprise (i) an instrument driver (alternatively referred to as “tool driver,” “instrument drive mechanism,” “instrument device manipulator,” and “drive input”) that incorporate electro-mechanical means for actuating the medical instrument, and (ii) a removable or detachable medical instrument, which may be devoid of any electro-mechanical components, such as motors. This dichotomy may be driven by the need to sterilize medical instruments used in medical procedures, and the inability to adequately sterilize expensive capital equipment due to their intricate mechanical assemblies and sensitive electronics. Accordingly, the medical instruments may be designed to be detached, removed, and interchanged from the instrument driver (and thus the system) for individual sterilization or disposal by the physician or the physician&#39;s staff. In contrast, the instrument drivers need not be changed or sterilized, and may be draped for protection. 
       FIG. 10  illustrates an example instrument driver  1000 , according to one or more embodiments. Positioned at the distal end of a robotic arm, the instrument driver  1000  includes one or more drive outputs  1002  arranged with parallel axes to provide controlled torque to a medical instrument via corresponding drive shafts  1004 . Each drive output  1002  comprises an individual drive shaft  1004  for interacting with the instrument, a gear head  1006  for converting the motor shaft rotation to a desired torque, a motor  1008  for generating the drive torque, and an encoder  1010  to measure the speed of the motor shaft and provide feedback to control circuitry  1012 , which can also be used for receiving control signals and actuating the drive output  1002 . Each drive output  1002  being independently controlled and motorized, the instrument driver  1000  may provide multiple (at least two shown in  FIG. 10 ) independent drive outputs to the medical instrument. In operation, the control circuitry  1012  receives a control signal, transmits a motor signal to the motor  1008 , compares the resulting motor speed as measured by the encoder  1010  with the desired speed, and modulates the motor signal to generate the desired torque. 
     For procedures that require a sterile environment, the robotic system may incorporate a drive interface, such as a sterile adapter connected to a sterile drape that sits between the instrument driver and the medical instrument. The chief purpose of the sterile adapter is to transfer angular motion from the drive shafts of the instrument driver to the drive inputs of the instrument while maintaining physical separation, and thus sterility, between the drive shafts and drive inputs. Accordingly, an example sterile adapter may comprise a series of rotational inputs and outputs intended to be mated with the drive shafts of the instrument driver and drive inputs on the instrument. Connected to the sterile adapter, the sterile drape, comprised of a thin, flexible material such as transparent or translucent plastic, is designed to cover the capital equipment, such as the instrument driver, robotic arm, and cart (in a cart-based system) or table (in a table-based system). Use of the drape would allow the capital equipment to be positioned proximate to the patient while still being located in an area not requiring sterilization (i.e., non-sterile field). On the other side of the sterile drape, the medical instrument may interface with the patient in an area requiring sterilization (i.e., sterile field). 
     D. Medical Instrument. 
       FIG. 11  illustrates an example medical instrument  1100  with a paired instrument driver  1102 . Like other instruments designed for use with a robotic system, the medical instrument  1100  (alternately referred to as a “surgical tool”) comprises an elongated shaft  1104  (or elongate body) and an instrument base  1106 . The instrument base  1106 , also referred to as an “instrument handle” due to its intended design for manual interaction by the physician, may generally comprise rotatable drive inputs  1108 , e.g., receptacles, pulleys or spools, that are designed to be mated with drive outputs  1110  that extend through a drive interface on the instrument driver  1102  at the distal end of a robotic arm  1112 . When physically connected, latched, and/or coupled, the mated drive inputs  1108  of the instrument base  1106  may share axes of rotation with the drive outputs  1110  in the instrument driver  1102  to allow the transfer of torque from the drive outputs  1110  to the drive inputs  1108 . In some embodiments, the drive outputs  1110  may comprise splines that are designed to mate with receptacles on the drive inputs  1108 . 
     The elongated shaft  1104  is designed to be delivered through either an anatomical opening or lumen, e.g., as in endoscopy, or a minimally invasive incision, e.g., as in laparoscopy. The elongated shaft  1104  may be either flexible (e.g., having properties similar to an endoscope) or rigid (e.g., having properties similar to a laparoscope) or contain a customized combination of both flexible and rigid portions. When designed for laparoscopy, the distal end of the shaft  1104  may be connected to an end effector extending from a jointed wrist formed from a clevis with at least one degree of freedom and a surgical tool or medical instrument, such as, for example, a grasper or scissors, that may be actuated based on force from the tendons as the drive inputs  1008  rotate in response to torque received from the drive outputs  1110  of the instrument driver  1102 . When designed for endoscopy, the distal end of the flexible elongated shaft  1104  may include a steerable or controllable bending section that may be articulated and bent based on torque received from the drive outputs  1110  of the instrument driver  1102 . 
     In some embodiments, torque from the instrument driver  1102  is transmitted down the elongated shaft  1104  using tendons along the shaft  1104 . These individual tendons, such as pull wires, may be individually anchored to individual drive inputs  1108  within the instrument handle  1106 . From the handle  1106 , the tendons are directed down one or more pull lumens along the elongated shaft  1104  and anchored at the distal portion of the elongated shaft  1104 , or in the wrist at the distal portion of the elongated shaft. During a surgical procedure, such as a laparoscopic, endoscopic, or a hybrid procedure, these tendons may be coupled to a distally mounted end effector, such as a wrist, a grasper, or scissors. Under such an arrangement, torque exerted on the drive inputs  1108  would transfer tension to the tendon, thereby causing the end effector to actuate in some way. In some embodiments, during a surgical procedure, the tendon may cause a joint to rotate about an axis, thereby causing the end effector to move in one direction or another. Alternatively, the tendon may be connected to one or more jaws of a grasper at distal end of the elongated shaft  1104 , where tension from the tendon cause the grasper to close. 
     In endoscopy, the tendons may be coupled to a bending or articulating section positioned along the elongated shaft  1104  (e.g., at the distal end) via adhesive, control ring, or other mechanical fixation. When fixedly attached to the distal end of a bending section, torque exerted on drive inputs  1108  would be transmitted down the tendons, causing the softer, bending section (sometimes referred to as the articulable section or region) to bend or articulate. Along the non-bending sections, it may be advantageous to spiral or helix the individual pull lumens that direct the individual tendons along (or inside) the walls of the endoscope shaft to balance the radial forces that result from tension in the pull wires. The angle of the spiraling and/or spacing there between may be altered or engineered for specific purposes, wherein tighter spiraling exhibits lesser shaft compression under load forces, while lower amounts of spiraling results in greater shaft compression under load forces, but also exhibits limits bending. On the other end of the spectrum, the pull lumens may be directed parallel to the longitudinal axis of the elongated shaft  1104  to allow for controlled articulation in the desired bending or articulable sections. 
     In endoscopy, the elongated shaft  1104  houses a number of components to assist with the robotic procedure. The shaft may comprise a working channel for deploying surgical tools (or medical instruments), irrigation, and/or aspiration to the operative region at the distal end of the shaft  1104 . The shaft  1104  may also accommodate wires and/or optical fibers to transfer signals to/from an optical assembly at the distal tip, which may include of an optical camera. The shaft  1104  may also accommodate optical fibers to carry light from proximally-located light sources, such as light emitting diodes, to the distal end of the shaft. 
     At the distal end of the instrument  1100 , the distal tip may also comprise the opening of a working channel for delivering tools for diagnostic and/or therapy, irrigation, and aspiration to an operative site. The distal tip may also include a port for a camera, such as a fiberscope or a digital camera, to capture images of an internal anatomical space. Relatedly, the distal tip may also include ports for light sources for illuminating the anatomical space when using the camera. 
     In the example of  FIG. 11 , the drive shaft axes, and thus the drive input axes, are orthogonal to the axis of the elongated shaft. This arrangement, however, complicates roll capabilities for the elongated shaft  1104 . Rolling the elongated shaft  1104  along its axis while keeping the drive inputs  1108  static results in undesirable tangling of the tendons as they extend off the drive inputs  1108  and enter pull lumens within the elongated shaft  1104 . The resulting entanglement of such tendons may disrupt any control algorithms intended to predict movement of the flexible elongated shaft during an endoscopic procedure. 
       FIG. 12  illustrates an alternative design for a circular instrument driver  1200  and corresponding instrument  1202  (alternately referred to as a “surgical tool”) where the axes of the drive units are parallel to the axis of the elongated shaft  1206  of the instrument  1202 . As shown, the instrument driver  1200  comprises four drive units with corresponding drive outputs  1208  aligned in parallel at the end of a robotic arm  1210 . The drive units and their respective drive outputs  1208  are housed in a rotational assembly  1212  of the instrument driver  1200  that is driven by one of the drive units within the assembly  1212 . In response to torque provided by the rotational drive unit, the rotational assembly  1212  rotates along a circular bearing that connects the rotational assembly  1212  to a non-rotational portion  1214  of the instrument driver  1200 . Power and control signals may be communicated from the non-rotational portion  1214  of the instrument driver  1200  to the rotational assembly  1212  through electrical contacts maintained through rotation by a brushed slip ring connection (not shown). In other embodiments, the rotational assembly  1212  may be responsive to a separate drive unit that is integrated into the non-rotatable portion  1214 , and thus not in parallel with the other drive units. The rotational assembly  1212  allows the instrument driver  1200  to rotate the drive units and their respective drive outputs  1208  as a single unit around an instrument driver axis  1216 . 
     Like earlier disclosed embodiments, the instrument  1202  may include an elongated shaft  1206  and an instrument base  1218  (shown in phantom) including a plurality of drive inputs  1220  (such as receptacles, pulleys, and spools) that are configured to mate with the drive outputs  1208  of the instrument driver  1200 . Unlike prior disclosed embodiments, the instrument shaft  1206  extends from the center of the instrument base  1218  with an axis substantially parallel to the axes of the drive inputs  1220 , rather than orthogonal as in the design of  FIG. 11 . 
     When coupled to the rotational assembly  1212  of the instrument driver  1200 , the medical instrument  1202 , comprising instrument base  1218  and instrument shaft  1206 , rotates in combination with the rotational assembly  1212  about the instrument driver axis  1216 . Since the instrument shaft  1206  is positioned at the center of the instrument base  1218 , the instrument shaft  1206  is coaxial with the instrument driver axis  1216  when attached. Thus, rotation of the rotational assembly  1212  causes the instrument shaft  1206  to rotate about its own longitudinal axis. Moreover, as the instrument base  1218  rotates with the instrument shaft  1206 , any tendons connected to the drive inputs  1220  in the instrument base  1218  are not tangled during rotation. Accordingly, the parallelism of the axes of the drive outputs  1208 , the drive inputs  1220 , and the instrument shaft  1206  allows for the shaft rotation without tangling any control tendons. 
       FIG. 13  illustrates a medical instrument  1300  having an instrument based insertion architecture in accordance with some embodiments. The instrument  1300  (alternately referred to as a “surgical tool”) can be coupled to any of the instrument drivers discussed herein above and, as illustrated, can include an elongated shaft  1302 , an end effector  1304  connected to the shaft  1302 , and a handle  1306  coupled to the shaft  1302 . The elongated shaft  1302  comprises a tubular member having a proximal portion  1308   a  and a distal portion  1308   b.  The elongated shaft  1302  comprises one or more channels or grooves  1310  along its outer surface and configured to receive one or more wires or cables  1312  therethrough. One or more cables  1312  thus run along an outer surface of the elongated shaft  1302 . In other embodiments, the cables  1312  can also run through the elongated shaft  1302 . Manipulation of the cables  1312  (e.g., via an instrument driver) results in actuation of the end effector  1304 . 
     The instrument handle  1306 , which may also be referred to as an instrument base, may generally comprise an attachment interface  1314  having one or more mechanical inputs  1316 , e.g., receptacles, pulleys or spools, that are designed to be reciprocally mated with one or more drive outputs on an attachment surface of an instrument driver. 
     In some embodiments, the instrument  1300  comprises a series of pulleys or cables that enable the elongated shaft  1302  to translate relative to the handle  1306 . In other words, the instrument  1300  itself comprises an instrument-based insertion architecture that accommodates insertion of the instrument  1300 , thereby minimizing the reliance on a robot arm to provide insertion of the instrument  1300 . In other embodiments, a robotic arm can be largely responsible for instrument insertion. 
     E. Controller. 
     Any of the robotic systems described herein can include an input device or controller for manipulating an instrument attached to a robotic arm. In some embodiments, the controller can be coupled (e.g., communicatively, electronically, electrically, wirelessly and/or mechanically) with an instrument such that manipulation of the controller causes a corresponding manipulation of the instrument e.g., via master slave control. 
       FIG. 14  is a perspective view of an embodiment of a controller  1400 . In the present embodiment, the controller  1400  comprises a hybrid controller that can have both impedance and admittance control. In other embodiments, the controller  1400  can utilize just impedance or passive control. In other embodiments, the controller  1400  can utilize just admittance control. By being a hybrid controller, the controller  1400  advantageously can have a lower perceived inertia while in use. 
     In the illustrated embodiment, the controller  1400  is configured to allow manipulation of two medical instruments, and includes two handles  1402 . Each of the handles  1402  is connected to a gimbal  1404 , and each gimbal  1404  is connected to a positioning platform  1406 . 
     As shown in  FIG. 14 , each positioning platform  1406  includes a selective compliance assembly robot arm (SCARA)  1408  coupled to a column  1410  by a prismatic joint  1412 . The prismatic joints  1412  are configured to translate along the column  1410  (e.g., along rails  1414 ) to allow each of the handles  1402  to be translated in the z-direction, providing a first degree of freedom. The SCARA arm  1408  is configured to allow motion of the handle  1402  in an x-y plane, providing two additional degrees of freedom. 
     In some embodiments, one or more load cells are positioned in the controller  1400 . For example, in some embodiments, a load cell (not shown) is positioned in the body of each of the gimbals  1404 . By providing a load cell, portions of the controller  1400  are capable of operating under admittance control, thereby advantageously reducing the perceived inertia of the controller  1400  while in use. In some embodiments, the positioning platform  1406  is configured for admittance control, while the gimbal  1404  is configured for impedance control. In other embodiments, the gimbal  1404  is configured for admittance control, while the positioning platform  1406  is configured for impedance control. Accordingly, for some embodiments, the translational or positional degrees of freedom of the positioning platform  1406  can rely on admittance control, while the rotational degrees of freedom of the gimbal  1404  rely on impedance control. 
     F. Navigation and Control. 
     Traditional endoscopy may involve the use of fluoroscopy (e.g., as may be delivered through a C-arm) and other forms of radiation-based imaging modalities to provide endoluminal guidance to an operator physician. In contrast, the robotic systems contemplated by this disclosure can provide for non-radiation-based navigational and localization means to reduce physician exposure to radiation and reduce the amount of equipment within the operating room. As used herein, the term “localization” may refer to determining and/or monitoring the position of objects in a reference coordinate system. Technologies such as pre-operative mapping, computer vision, real-time EM tracking, and robot command data may be used individually or in combination to achieve a radiation-free operating environment. In other cases, where radiation-based imaging modalities are still used, the pre-operative mapping, computer vision, real-time EM tracking, and robot command data may be used individually or in combination to improve upon the information obtained solely through radiation-based imaging modalities. 
       FIG. 15  is a block diagram illustrating a localization system  1500  that estimates a location of one or more elements of the robotic system, such as the location of the instrument, in accordance to an example embodiment. The localization system  1500  may be a set of one or more computer devices configured to execute one or more instructions. The computer devices may be embodied by a processor (or processors) and computer-readable memory in one or more components discussed above. By way of example and not limitation, the computer devices may be in the tower  112  shown in  FIG. 1 , the cart  102  shown in  FIGS. 1-3B , the beds shown in  FIGS. 4-9 , etc. 
     As shown in  FIG. 15 , the localization system  1500  may include a localization module  1502  that processes input data  1504   a,    1504   b,    1504   c,  and  1504   d  to generate location data  1506  for the distal tip of a medical instrument. The location data  1506  may be data or logic that represents a location and/or orientation of the distal end of the instrument relative to a frame of reference. The frame of reference can be a frame of reference relative to the anatomy of the patient or to a known object, such as an EM field generator (see discussion below for the EM field generator). 
     The various input data  1504   a - d  are now described in greater detail. Pre-operative mapping may be accomplished through the use of the collection of low dose CT scans. Pre-operative CT scans are reconstructed into three-dimensional images, which are visualized, e.g. as “slices” of a cutaway view of the patient&#39;s internal anatomy. When analyzed in the aggregate, image-based models for anatomical cavities, spaces and structures of the patient&#39;s anatomy, such as a patient lung network, may be generated. Techniques such as center-line geometry may be determined and approximated from the CT images to develop a three-dimensional volume of the patient&#39;s anatomy, referred to as model data  1504   a  (also referred to as “preoperative model data” when generated using only preoperative CT scans). The use of center-line geometry is discussed in U.S. patent application Ser. No. 14/523,760, the contents of which are herein incorporated in its entirety. Network topological models may also be derived from the CT-images, and are particularly appropriate for bronchoscopy. 
     In some embodiments, the instrument may be equipped with a camera to provide vision data  1504   b.  The localization module  1502  may process the vision data  1504   b  to enable one or more vision-based location tracking. For example, the preoperative model data may be used in conjunction with the vision data  1504   b  to enable computer vision-based tracking of the medical instrument (e.g., an endoscope or an instrument advance through a working channel of the endoscope). For example, using the preoperative model data  1504   a,  the robotic system may generate a library of expected endoscopic images from the model based on the expected path of travel of the endoscope, each image linked to a location within the model. Intra-operatively, this library may be referenced by the robotic system in order to compare real-time images captured at the camera (e.g., a camera at a distal end of the endoscope) to those in the image library to assist localization. 
     Other computer vision-based tracking techniques use feature tracking to determine motion of the camera, and thus the endoscope. Some features of the localization module  1502  may identify circular geometries in the preoperative model data  1504   a  that correspond to anatomical lumens and track the change of those geometries to determine which anatomical lumen was selected, as well as the relative rotational and/or translational motion of the camera. Use of a topological map may further enhance vision-based algorithms or techniques. 
     Optical flow, another computer vision-based technique, may analyze the displacement and translation of image pixels in a video sequence in the vision data  1504   b  to infer camera movement. Examples of optical flow techniques may include motion detection, object segmentation calculations, luminance, motion compensated encoding, stereo disparity measurement, etc. Through the comparison of multiple frames over multiple iterations, movement and location of the camera (and thus the endoscope) may be determined. 
     The localization module  1502  may use real-time EM tracking to generate a real-time location of the endoscope in a global coordinate system that may be registered to the patient&#39;s anatomy, represented by the preoperative model. In EM tracking, an EM sensor (or tracker) comprising of one or more sensor coils embedded in one or more locations and orientations in a medical instrument (e.g., an endoscopic tool) measures the variation in the EM field created by one or more static EM field generators positioned at a known location. The location information detected by the EM sensors is stored as EM data  1504   c.  The EM field generator (or transmitter), may be placed close to the patient to create a low intensity magnetic field that the embedded sensor may detect. The magnetic field induces small currents in the sensor coils of the EM sensor, which may be analyzed to determine the distance and angle between the EM sensor and the EM field generator. These distances and orientations may be intra-operatively “registered” to the patient anatomy (e.g., the preoperative model) in order to determine the geometric transformation that aligns a single location in the coordinate system with a position in the pre-operative model of the patient&#39;s anatomy. Once registered, an embedded EM tracker in one or more positions of the medical instrument (e.g., the distal tip of an endoscope) may provide real-time indications of the progression of the medical instrument through the patient&#39;s anatomy. 
     Robotic command and kinematics data  1504   d  may also be used by the localization module  1502  to provide localization data  1506  for the robotic system. Device pitch and yaw resulting from articulation commands may be determined during pre-operative calibration. Intra-operatively, these calibration measurements may be used in combination with known insertion depth information to estimate the position of the instrument. Alternatively, these calculations may be analyzed in combination with EM, vision, and/or topological modeling to estimate the position of the medical instrument within the network. 
     As  FIG. 15  shows, a number of other input data can be used by the localization module  1502 . For example, although not shown in  FIG. 15 , an instrument utilizing shape-sensing fiber can provide shape data that the localization module  1502  can use to determine the location and shape of the instrument. 
     The localization module  1502  may use the input data  1504   a - d  in combination(s). In some cases, such a combination may use a probabilistic approach where the localization module  1502  assigns a confidence weight to the location determined from each of the input data  1504   a - d.  Thus, where the EM data  1504   c  may not be reliable (as may be the case where there is EM interference) the confidence of the location determined by the EM data  1504   c  can be decrease and the localization module  1502  may rely more heavily on the vision data  1504   b  and/or the robotic command and kinematics data  1504   d.    
     As discussed above, the robotic systems discussed herein may be designed to incorporate a combination of one or more of the technologies above. The robotic system&#39;s computer-based control system, based in the tower, bed and/or cart, may store computer program instructions, for example, within a non-transitory computer-readable storage medium such as a persistent magnetic storage drive, solid state drive, or the like, that, upon execution, cause the system to receive and analyze sensor data and user commands, generate control signals throughout the system, and display the navigational and localization data, such as the position of the instrument within the global coordinate system, anatomical map, etc. 
     2. Description. 
     Embodiments of this disclosure relate to rack-based robotic surgical tools capable of facilitating z-axis translation of a shaft and actuation of a knife at an end effector, depending on the configuration of a shifting mechanism. At least one robotic surgical tool includes a handle providing a first drive input and a second drive input, an elongate shaft extendable through the handle and having an end effector arranged at a distal end thereof, and rack extending along a portion of the shaft and operatively coupled to a knife located at the end effector, wherein actuation of the first drive input transitions the rack between a locked configuration, where the rack is locked to the shaft, and a released configuration, where the rack is released from the shaft, wherein actuation of the second drive input with the rack in the locked configuration drives the rack and causes z-axis translation of the shaft through the handle, and wherein actuation of the second drive input with the rack in the released configuration drives the rack relative to the shaft and thereby advances or retracts the knife at the end effector. 
       FIG. 16  is an isometric side view of an example surgical tool  1600  that may incorporate some or all of the principles of the present disclosure. The surgical tool  1600  may be similar in some respects to any of the surgical tools and medical instruments described above with reference to  FIGS. 11-13  and, therefore, may be used in conjunction with a robotic surgical system, such as the robotically-enabled systems  100 ,  400 , and  900  of  FIGS. 1-9C . As illustrated, the surgical tool  1600  includes an elongated shaft  1602 , an end effector  1604  arranged at the distal end of the shaft  1602 , and an articulable wrist  1606  (alternately referred to as a “wrist joint”) that interposes and couples the end effector  1604  to the distal end of the shaft  1602 . In some embodiments, the wrist  1606  may be omitted, without departing from the scope of the disclosure. 
     The terms “proximal” and “distal” are defined herein relative to a robotic surgical system having an interface configured to mechanically and electrically couple the surgical tool  1600  to a robotic manipulator. The term “proximal” refers to the position of an element closer to the robotic manipulator and the term “distal” refers to the position of an element closer to the end effector  1604  and thus closer to the patient during operation. Moreover, the use of directional terms such as above, below, upper, lower, upward, downward, left, right, and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward or upper direction being toward the top of the corresponding figure and the downward or lower direction being toward the bottom of the corresponding figure. 
     The surgical tool  1600  can have any of a variety of configurations capable of performing one or more surgical functions. In the illustrated embodiment, the end effector  1604  comprises a surgical stapler, alternately referred to as an “endocutter,” configured to cut and staple (fasten) tissue. As illustrated, the end effector  1604  includes opposing jaws  1610  and  1612  configured to move (articulate) between open and closed positions. Alternatively, the end effector  1604  may comprise other types of instruments with opposing jaws such as, but not limited to, other types of surgical staplers (e.g., circular and linear staplers), tissue graspers, surgical scissors, advanced energy vessel sealers, clip appliers, needle drivers, a babcock including a pair of opposed grasping jaws, bipolar jaws (e.g., bipolar Maryland grasper, forceps, a fenestrated grasper, etc.), etc. In other embodiments, the end effector  1604  may instead comprise any end effector or instrument capable of being operated in conjunction with the presently disclosed robotic surgical systems and methods, such as a suction irrigator, an endoscope (e.g., a camera), or any combination thereof. 
     One or both of the jaws  1610 ,  1612  may be configured to pivot to actuate the end effector  1604  between open and closed positions. In the illustrated example, the second jaw  1612  may be rotatable (pivotable) relative to the first jaw  1610  to actuate the end effector  1604  between an open, unclamped position and a closed, clamped position. In other embodiments, however, the first jaw  1610  may move (rotate) relative to the second jaw  1612  to move the jaws  1610 ,  1612  between open and closed positions. In yet other embodiments, both jaws  1610 ,  1612  may simultaneously move between open and closed positions (e.g., bifurcating jaws). 
     In the illustrated example, the first jaw  1610  is referred to as a “cartridge” or “channel” jaw, and the second jaw  1612  is referred to as an “anvil” jaw. The first jaw  1610  includes a frame that houses or supports a staple cartridge, and the second jaw  1612  is pivotally supported relative to the first jaw  1610  and defines a surface that operates as an anvil to deform staples ejected from the staple cartridge during operation. 
     The wrist  1606  enables the end effector  1604  to articulate (pivot) relative to the shaft  1602  and thereby position the end effector  1604  at various desired orientations and locations relative to a surgical site. In the illustrated embodiment, the wrist  1606  is designed to allow the end effector  1604  to pivot (swivel) left and right relative to a longitudinal axis A 1  of the shaft  1602 . In other embodiments, however, the wrist  1606  may be designed to provide multiple degrees of freedom, including one or more translational variables (i.e., surge, heave, and sway) and/or one or more rotational variables (i.e., Euler angles or roll, pitch, and yaw). The translational and rotational variables describe the position and orientation of a component of a surgical system (e.g., the end effector  1604 ) with respect to a given reference Cartesian frame. “Surge” refers to forward and backward translational movement, “heave” refers to translational movement up and down, and “sway” refers to translational movement left and right. With regard to the rotational terms, “roll” refers to tilting side to side, “pitch” refers to tilting forward and backward, and “yaw” refers to turning left and right. 
     The end effector  1604  is depicted in  FIG. 16  in the unarticulated position where the centerline of the end effector  1604  is substantially aligned with the longitudinal axis A 1  of the shaft  1602 , such that the end effector  1604  is at a substantially zero angle relative to the shaft  1602 . In the articulated position, the centerline of the end effector  1604  would be angularly offset from the longitudinal axis A 1  such that the end effector  1604  would be oriented at a non-zero angle relative to the shaft  1602 . 
     Still referring to  FIG. 16 , the surgical tool  1600  may include a drive housing or “handle”  1614 , and the shaft  1602  extends longitudinally through the handle  1614 . The handle  1614  houses various actuation systems designed to operate the surgical tool. At least one actuation system, for example, may be designed to move the shaft  1602  relative to the handle  1614  (i.e., z-axis translation), as indicated by the arrows B, and thereby advance or retract the end effector  1604 . Other actuation systems may be designed to facilitate articulation of the wrist  1606  and actuation (operation) of the end effector  1604  (e.g., clamping, firing, rotation, articulation, energy delivery, etc.). Some of the actuation systems and mechanisms housed within the handle  1614  are actuatable to move (translate) a plurality of drive members (mostly obscured in  FIG. 16 ) that extend along at least a portion of the shaft  1602 , either on the exterior or within the interior of the shaft  1602 . Example drive members include, but are not limited to, cables, bands, lines, cords, wires, woven wires, ropes, strings, twisted strings, elongate members, belts, shafts, flexible shafts, drive rods, or any combination thereof. The drive members can be made from a variety of materials including, but not limited to, a metal (e.g., tungsten, stainless steel, nitinol, etc.) a polymer (e.g., ultra-high molecular weight polyethylene), a synthetic fiber (e.g., KEVLAR®, VECTRAN®, etc.), an elastomer, or any combination thereof. 
     Selective actuation of one or more of the drive members, for example, may cause the end effector  1604  to articulate (pivot) relative to the shaft  1602  at the wrist  1606 . Selective actuation of one or more additional drive members may cause the end effector  1604  to actuate (operate). Actuating the end effector  1604  depicted in  FIG. 16  may entail closing and/or opening the jaws,  1610 ,  1612  and thereby enabling the end effector  1604  to grasp (clamp) onto tissue. Once tissue is grasped or clamped between the opposing jaws  1610 ,  1612 , actuating the end effector  1604  may further include “firing” the end effector  1604 , which may refer to causing a cutting element or knife (not visible) to advance distally within a slot or “guide track”  1616  defined in the first jaw  1610 . As it moves distally, the knife transects any tissue grasped between the opposing jaws  1610 ,  1612 . Moreover, as the knife advances distally, a plurality of staples contained within the staple cartridge (e.g., housed within the first jaw  1610 ) are urged (cammed) into deforming contact with corresponding anvil surfaces (e.g., pockets) provided on the second jaw  1612 . The deployed staples may form multiple rows of staples that seal opposing sides of the transected tissue. 
     As will be appreciated, however, the end effector  1604  may be replaced with any of the other types of end effectors mentioned herein, and in those cases actuating the end effector  1604  may entail a variety of other actions or movements, without departing from the scope of the disclosure. For example, in some embodiments, the end effector  1604  may be replaced with a vessel sealer and actuating such an end effector  1604  may further entail triggering energy delivery (e.g., RF energy) to cauterize and/or seal tissue or vessels. 
     The handle  1614  provides or otherwise includes various coupling features (not shown) that releasably couple the surgical tool  1600  to an instrument driver  1618  (shown in dashed lines) of a robotic surgical system. The instrument driver  1618  may be similar in some respects to the instrument drivers  1102 ,  1200  of  FIGS. 11 and 12 , respectively, and therefore may be best understood with reference thereto. Similar to the instrument drivers  1102 ,  1200 , for example, the instrument driver  1618  may be mounted to or otherwise positioned at the end of a robotic arm (not shown) and is designed to provide the motive forces required to operate the surgical tool  1600 . Unlike the instrument drivers  1102 ,  1200 , however, the shaft  1602  of the surgical tool  1600  extends through and penetrates the instrument driver  1618 . 
     The handle  1614  includes one or more rotatable drive inputs matable with one or more corresponding drive outputs (not shown) of the instrument driver  1618 . Each drive input is actuatable to independently drive (actuate) the actuation systems and mechanisms housed within the handle  1614  and thereby operate the surgical tool  1600 . In the illustrated embodiment, the handle  1614  includes a first drive input  1620   a,  a second drive input  1620   b,  a third drive input  1620   c,  a fourth drive input  1620   d,  a fifth drive input  1620   e,  and a sixth drive input  1620   f  While six drive inputs  1620   a - f  are depicted, more or less than six may be included in the handle  1614  depending on the application, and without departing from the scope of the disclosure. Each drive input  1620   a - f  may be matable with a corresponding drive output (not shown) of the instrument driver  1618  such that movement (rotation) of a given drive output correspondingly moves (rotates) the associated drive input  1620   a - f  and thereby causes various operations of the surgical tool  1600 . 
     In some embodiments, actuation of the first drive input  1620   a  may cause the knife to fire at the end effector  1604 , thus advancing or retracting the knife, depending on the rotational direction of the first drive input  1620   a.  Actuation of the third drive input  1620   c  may cause the shaft  1602  to move (translate) relative to the handle  1614  along the longitudinal axis A 1 , depending on the rotational direction of the third drive input  1620   c.  In some embodiments, and as discussed in more detail herein, actuation of the second drive input  1620   b  may shift operation or activation within the handle  1614  between the first and third drive inputs  1620   a,c.  Consequently, actuation of the second drive input  1620   b  will dictate whether the knife is fired or whether the shaft  1602  is moved (translated). Actuation of the fourth drive input  1620   d  may lock and unlock z-axis translation of the shaft  1602 , and actuation of the fifth drive input  1620   e  may cause articulation of the end effector  1604  at the wrist  1606 . Lastly, actuation of the sixth drive input  1620   f  may cause the jaws  1610 ,  1612  to open or close, depending on the rotational direction of the sixth drive input  1620   f.  In some embodiments, for example, actuation of the sixth drive input  1620   f  may operate a toggle mechanism  1622  arranged at the proximal end of the shaft  1602 , and actuation of the toggle mechanism  1622  may cause the jaws  1610 ,  1612  to open and close. 
       FIG. 17  depicts separated isometric end views of the instrument driver  1618  and the surgical tool  1600  of  FIG. 16 . With the jaws  1610 ,  1612  closed, the shaft  1602  and the end effector  1604  can penetrate the instrument driver  1618  by extending through a central aperture  1702  defined longitudinally through the instrument driver  1618  between first and second ends  1704   a,b.  In some embodiments, to align the surgical tool  1600  with the instrument driver  1618  in a proper angular orientation, one or more alignment guides  1706  may be provided or otherwise defined within the central aperture  1702  and configured to engage one or more corresponding alignment features (not shown) provided on the surgical tool  1600 . The alignment feature(s) may comprise, for example, a protrusion or projection (not shown) defined on or otherwise provided by an alignment nozzle  1708  extending distally from the handle  1614 . 
     In one or more embodiments, the alignment guide(s)  1706  may comprise a curved or arcuate shoulder or lip configured to receive and guide the alignment feature as the alignment nozzle  1708  enters the central aperture  1702 . As a result, the surgical tool  1600  is oriented to a proper angular alignment with the instrument driver  1618  as the alignment nozzle  1708  is advanced distally through the central aperture  1702 . In other embodiments, the alignment nozzle  1708  may be omitted and the alignment feature  1712  may alternatively be provided on the shaft  1602 , without departing from the scope of the disclosure. 
     A drive interface  1710  is provided at the first end  1704   a  of the instrument driver  1618  and is matable with a driven interface  1712  provided on the distal end of the handle  1614 . The drive and driven interfaces  1710 ,  1712  may be configured to mechanically, magnetically, and/or electrically couple the handle  1614  to the instrument driver  1618 . To accomplish this, in some embodiments, the drive and driven interfaces  1710 ,  1712  may provide one or more matable locating features configured to secure the handle  1614  to the instrument driver  1618 . In the illustrated embodiment, for example, the drive interface  1710  provides one or more interlocking features  1714  (three shown) configured to locate and mate with one or more complementary-shaped pockets  1716  (two shown, one occluded) provided on the driven interface  1712 . In some embodiments, the features  1714  may be configured to align and mate with the pockets  1716  via an interference or snap fit engagement, for example. 
     The instrument driver  1618  also includes one or more drive outputs that extend through the drive interface  1710  to mate with corresponding drive inputs  1620   a - f  provided at the distal end of the handle  1614 . More specifically, the instrument driver  1618  includes a first drive output  1718   a  matable with the first drive input  1620   a,  a second drive output  1718   b  matable with the second drive input  1620   b,  a third drive output  1718   b  matable with the third drive input  1620   c,  a fourth drive output  1718   d  matable with the fourth drive input  1620   d,  a fifth drive output  1718 e matable with the fifth drive input  1620   e,  and a sixth drive output  1718   f  matable with the sixth drive input  1620   f.  In some embodiments, as illustrated, the drive outputs  1718   a - f  may define splines or features designed to mate with corresponding splined receptacles of the drive inputs  1620   a - f  Once properly mated, the drive inputs  1620   a - f  will share axes of rotation with the corresponding drive outputs  1718   a - f  to allow the transfer of rotational torque from the drive outputs  1718   a - f  to the corresponding drive inputs  1620   a - f.  In some embodiments, each drive output  1718   a - f  may be spring loaded and otherwise biased to spring outwards away from the drive interface  1710 . Each drive output  1718   a - f  may be capable of partially or fully retracting into the drive interface  1710 . 
     In some embodiments, the instrument driver  1618  may include additional drive outputs, depicted in  FIG. 17  as a seventh drive output  1718   g.  The seventh drive output  1718   g  may be configured to mate with additional drive inputs (not shown) of the handle  1614  to help undertake one or more additional functions of the surgical tool  1600 . In the illustrated embodiment, however, the handle  1614  does not include additional drive inputs matable with the seventh drive output  1718   g.  Instead, the driven interface  1712  defines a corresponding recess  1720  (partially occluded) configured to receive the seventh drive output  1718   g.  In other applications, however, a seventh drive input (not shown) could be included in the handle  1614  to mate with the seventh drive output  1718   g,  or the surgical tool  1600  might be replaced with another surgical tool having a seventh drive input, which would be driven by the seventh drive output  1718   g.    
     While not shown, in some embodiments, an instrument sterile adapter (ISA) may be placed at the interface between the instrument driver  1618  and the handle  1614 . In such applications, the interlocking features  1714  may operate as alignment features and possible latches for the ISA to be placed, stabilized, and secured. Stability of the ISA may be accomplished by a nose cone feature provided by the ISA and extending into the central aperture  1702  of the instrument driver  1618 . Latching can occur either with the interlocking features  1714  or at other locations at the interface. In some cases, the ISA will provide the means to help align and facilitate the latching of the surgical tool  1600  to the ISA and simultaneously to the instrument driver  1618 . 
     Robotic Instruments with Rack-Based Translation and Firing Transmission 
       FIGS. 18A and 18B  are enlarged isometric views of the handle  1614  from different side perspective views and depicting an example actuation system  1800 , according to one or more embodiments of the present disclosure. The outer body of the handle  1614  is shown in phantom (dashed lines) to enable viewing of the internal space within the handle  1614 , including the actuation system  1800 . Various other actuation systems and component parts of the handle  1614  are omitted in  FIGS. 18A-18B  for simplicity. 
     The actuation system  1800  may be operable (actuatable) to carry out a variety of functions (operations) of the surgical tool  1600  ( FIG. 16 ). More specifically, the actuation system  1800  may be actuatable between first and second configurations to perform at least two functions (operations) of the surgical tool  1600 . In the first configuration, for example, operation of the actuation system  1800  may cause the shaft  1602  to move relative to the handle  1614  in z-axis translation, and thereby longitudinally advance or retract the end effector  1604  ( FIG. 16 ) arranged at the distal end of the shaft  1602 . In the second configuration, however, operation of the actuation system  1800  may secure the shaft  1602  and cause the end effector  1604  to “fire,” as generally described above. 
     As best seen in  FIG. 18A , the shaft  1602  may include an outer shaft portion  1802  and a rack  1804  may be at least partially received within a longitudinal channel  1806  defined in the outer shaft portion  1802 . As illustrated, the rack  1804  may define gear teeth along at least a portion of its length. As described in more detail below, the rack  1804  may be locked (secured) to or unlocked (released) from the outer shaft portion  1802  (i.e., the shaft  1602 ) during operation of the actuation system  1800 . More specifically, when the actuation system  1800  is in the first configuration, the rack  1804  will be locked to the shaft  1602 , such that driving the rack  1804  will cause the shaft  1602  to move relative to the handle  1614  in z-axis translation. In contrast, when the actuation system  1800  is transitioned to the second configuration, the shaft  1602  will be secured against movement and the rack  1804  will be released from the shaft  1602 , such that driving the rack  1804  will cause the rack  1804  to move relative to the shaft  1602  and translate (slide) within the channel  1806 . The rack  1804  may extend distally and be operatively coupled (either directly or indirectly) to a knife arranged at the end effector  1604  ( FIG. 16 ). Consequently, when the actuation system  1800  is in the second configuration, movement of the rack  1804  relative to the shaft  1602  will cause the knife to advance or retract at the end effector  1604 . 
     As illustrated, the actuation system  1800  includes a first drive shaft or “capstan”  1808   a  coupled to or forming part of the third drive input  1620   c,  such that rotation of the third drive input  1620   c  correspondingly rotates the first capstan  1808   a  in the same direction. A first helical drive gear  1810   a  is coupled to or forms part of the first capstan  1808   a  and rotates as the first capstan  1808   a  rotates. The first helical drive gear  1810   a  may be configured to intermesh with and drive a gear train  1812  (best seen in  FIG. 18A ) that includes one or more interconnected gears configured to ultimately intermesh with and drive the rack  1804 . 
     Accordingly, rotation (actuation) of the first capstan  1808   a  may correspondingly drive the rack  1804  via operation of the gear train  1812 . In the illustrated embodiment, the gear train  1812  includes a first helical driven gear  1814   a,  a spur drive gear  1818 , a spur driven gear  1820 , and a pinion gear  1822  ( FIG. 18A ). While the gear train  1812  is depicted as including four geared components, those skilled in the art will readily appreciate that the gear train  1812  may include more or less than four geared components to drive the rack  1804 , without departing from the scope of the disclosure. 
     In the illustrated embodiment, the first helical driven gear  1814   a  and the spur drive gear  1818  may each be mounted to a first axle  1824   a.  The first helical driven gear  1814   a  may be configured to drive the spur drive gear  1818 , as driven by the first helical drive gear  1810   a.  In some embodiments, the spur drive gear  1818  may form an integral part or extension of the first helical driven gear  1814   a,  such that any rotation of the first helical driven gear  1814   a  will correspondingly rotate the spur drive gear  1818 . In other embodiments, however, the spur drive gear  1818  may form part of a slip-type clutch  1826  (best seen in  FIG. 18A ) configured to engage and disengage the first helical driven gear  1814   a  at a first clutch interface  1827   a.  Specifics of the clutch  1826  will be provided in more detail below. 
     The spur drive gear  1818  may be arranged to drive the spur driven gear  1820 , which may be fixed to a second axle  1824   b  such that rotation of the spur driven gear  1820  will correspondingly rotate the second axle  1824   b  in the same direction. The pinion gear  1822  may be coupled to or form part of the second axle  1824   b,  such that rotation of the second axle  1824   b  correspondingly rotates the pinion gear  1822 . As illustrated, the gear teeth of the pinion gear  1822  may intermesh with the gear teeth of the rack  1804  such that rotation of the pinion gear  1822  drives or urges the rack  1804  proximally or distally, depending on the rotation direction of the pinion gear  1822 . When the actuation system  1800  is in the first configuration, the rack  1804  will be locked to the shaft  1602 , such that driving the rack  1804  via rotation of the pinion gear  1822  will move the shaft  1602  relative to the handle  1614  in z-axis translation. When the actuation system  1800  is transitioned to the second configuration, however, the shaft  1602  will be secured against movement and the rack  1804  will be released from the shaft  1602 , such that driving the rack  1804  via rotation of the pinion gear  1822  will cause the rack  1804  to move independent of the shaft  1602  and advance or retract a knife arranged at the end effector  1604  ( FIG. 16 ). 
     The actuation system  1800  may further include a shifting mechanism  1828  operable or otherwise actuatable to transition the actuation system  1800  between the first and second configurations. In the illustrated embodiment, the shifting mechanism  1828  includes an armature  1830  coupled to or forming an integral part of the second drive input  1620   b  such that movement (rotation) of the second drive input  1620   c  correspondingly moves (rotates) the armature  1830 . In some embodiments, the armature  1830  may be eccentrically mounted to the second drive input  1620   b,  such as being mounted to a pin  1832  that extends eccentric to a rotation axis of the second drive input  1620   b.  Mounting the armature  1830  to the eccentric pin  1832  may provide a camming effect on the armature  1830  as the second drive input  1620   b  is actuated (rotated). More specifically, rotational input from the second drive input  1620   b  will move the armature  1830  laterally, thus allowing two inputs  1620   a  and  1620   c  with potentially different gear ratios to drive the same rack  1804 , as described in more detail below. 
     The actuation system  1800  may also include a drive member  1834  that extends longitudinally along at least a portion of the shaft  1602 . In the illustrated embodiment, the drive member  1834  comprises a cable or wire and, therefore, will be referred to herein as “the drive cable  1834 ”. In other embodiments, however, the drive cable  1834  may comprise any of the other types of drive members mentioned herein. As illustrated, the drive cable  1834  may be received and extend within a groove  1836  defined in the shaft  1602 . In other embodiments, however, the drive cable  1834  may alternatively be received within the interior of the shaft  1602  or extend along an exterior surface of the shaft  1602 , without departing from the scope of the disclosure. 
     As best seen in  FIG. 18B , a first or “distal” end  1838   a  ( FIG. 18B ) of the drive cable  1834  may be anchored to the shaft  1602  below (distal to) the handle  1614  and at a distance sufficient to allow the shaft  1602  to translate relative to the handle  1614 . As described in more detail below, a second or “proximal” end  1838   b  (see  FIG. 19 ) of the drive cable  1834  may be secured at or near a proximal end of the shaft  1602  and above (proximal to) the handle  1614 . The proximal end  1838   b  of the drive cable  1834  may be operatively coupled to a rack locking assembly  1900  (see  FIG. 19 ) and actuation of the shifting mechanism  1828  may cause the drive cable  1834  to act on the rack locking assembly  1900 , which may be designed to lock or release the rack  1804  relative to the shaft  1602 . 
     As illustrated, the drive cable  1834  may also extend or be threaded (guided) to the armature  1830  of the shifting mechanism  1828 . More specifically, the shifting mechanism  1828  may include a plurality of pulleys through which the drive cable  1834  may be threaded. As illustrated, the shifting mechanism  1828  may include a side accumulator pulley  1840  rotatably mounted to the armature  1830 , and may further include a first or “upper” accumulator pulley  1842   a  and a second or “lower” accumulator pulley  1842   b  arranged adjacent the side accumulator pulley  1840  and rotatably coupled to the handle  1614 . As best seen in  FIG. 18B , the shifting mechanism  1828  may further include a first or “upper” idler pulley  1844   a  and a second or “lower” idler pulley  1844   b.  Similar to the upper and lower accumulator pulleys  1842   a,b,  the upper and lower idler pulleys  1844   a,b  may each be rotatably coupled to the handle  1614 . 
     The upper idler pulley  1844   a  may be arranged and otherwise configured to redirect the drive cable  1834  between the shaft  1602  and the upper accumulator pulley  1842   a,  and the lower idler pulley  1844   b  may be arranged and otherwise configured to redirect the drive cable  1834  between the shaft  1602  and the lower accumulator pulley  1842   b.  The side accumulator pulley  1840  may be arranged to receive and redirect the drive cable  1834  between the upper and lower accumulator pulleys  1842   a,b.  In some embodiments, as illustrated, the upper and lower accumulator pulleys  1842   a,b  may be arranged for rotation in respective parallel planes, while the side accumulator pulley  1840  may be arranged for rotation in a plane that is 90° offset from the parallel planes in order to redirect the drive cable  1834  between the upper and lower accumulator pulleys  1842   a,b.  In one embodiment, for example, the parallel planes of the upper and lower accumulator pulleys  1842   a,b  may be characterized as extending substantially horizontal, and the plane of the side accumulator pulley  1840  may be characterized as extending substantially vertical and otherwise 90° offset from the horizontal planes. In other embodiments, however, the planes of the upper and lower accumulator pulleys  1842   a,b  and the side accumulator pulley  1840  need not be 90° offset from each other. Moreover, the upper and lower accumulator pulleys  1842   a,b  need not be arranged for rotation in respective parallel planes, but may alternatively be arranged in non-parallel planes, without departing from the scope of the disclosure. 
     As mentioned above, the shifting mechanism  1828  may be actuated or operated by rotating the second drive input  1620   b,  via operation of the second drive output  1718   b  ( FIG. 17 ). Rotating the second drive input  1620   b  will correspondingly rotate the armature  1830  in the same direction. Because the distal end  1838   a  of the drive cable  1834  is anchored to the shaft  1602  distal to the handle  1614 , the drive cable  1834  may be drawn (pulled) into the armature  1830  at the upper accumulator pulley  1842   a  as the armature  1830  rotates. Upon reversing rotation direction of the second drive input  1620   b,  the armature  1830  will correspondingly rotate in the opposite direction and a length of the drive cable  1834  may correspondingly be paid out (fed) to the shaft  1602  from the upper accumulator pulley  1842   a.  As discussed below with respect to  FIG. 19 , drawing in or paying out the drive cable  1834  at the armature  1830  correspondingly acts on the rack locking assembly  1900  of  FIG. 19  arranged at or near the proximal end of the shaft  1602 , and operation of the rack locking assembly  1900  may lock or release the rack  1804  relative to the shaft  1602 , depending on the direction of the drive cable  1834 . 
     In some embodiments, the shifting mechanism  1828  may be decoupled from shaft  1602  insertion. More specifically, the side, upper, and lower accumulator pulleys  1840 ,  1842   a,b  and the idler pulleys  1844   a,b  are able to freely rotate (e.g., “free wheel”) and are otherwise not driven during operation of the handle  1614 . Consequently, as the shaft  1602  moves longitudinally relative to the handle  1614  in z-axis translation, the drive cable  1834  is able to freely run (course) through the armature  1830  between the upper and lower idler pulleys  1844   a,b.    
       FIG. 19  is an enlarged front view of an example rack locking assembly  1900 , according to one or more embodiments of the disclosure. As illustrated, the rack locking assembly  1900  may be arranged at or near a proximal end  1902  of the shaft  1602  and may include a latch  1904  pivotably coupled to the shaft  1602  and engageable with the rack  1804 . The drive cable  1834  extends proximally from the handle  1614  ( FIGS. 18A-18B ) to the rack locking assembly  1900 , and the proximal end  1838   b  of the drive cable  1834  may be secured (anchored) to the latch  1904  to enable the latch  1904  to pivot during operation. 
     The latch  1904 , alternately referred to as a “rocker latch,” may include or otherwise define various features that are engageable with the rack  1804  at or near its proximal end to lock and release the rack  1804  relative to the shaft  1602 . In some embodiments, for example, the latch  1904  may provide a first flange  1906   a  engageable with a downstop recess  1908   a  defined on the rack  1804 , and a second flange  1906   b  engageable with an upstop recess  1908   b  defined on the rack  1804 . The downstop and upstop recesses  1908   a,b  may comprise cutouts in the rack  1804  sized to receive and seat the first and second flanges  1906   a,b,  respectively. When the first flange  1906   a  is engaged with the downstop recess  1908   a,  the rack  1804  will be prevented from moving distally (e.g., down in  FIG. 19 ) relative to the remaining portions of the shaft  1602 , and when the second flange  1906   b  is engaged with the upstop recess  1908   b,  the rack  1804  will be prevented from moving proximally (e.g., up in  FIG. 19 ) relative to the remaining portions of the shaft  1602 . Accordingly, when the first and second flanges  1906   a,b  are received within the downstop and upstop recesses  1908   a,b,  respectively, any proximal or distal movement of the rack  1804  will correspondingly move the remaining portions of the shaft  1602 . 
     The latch  1904  may be pivotable between a first or “locked” position, where the first and second flanges  1906   a,b  are received within the downstop and upstop recesses  1908   a,b,  respectively, and a second or “released” position, where the first and second flanges  1906   a,b  are pivoted out of engagement with the downstop and upstop recesses  1908   a,b,  respectively. The latch  1904  is shown in  FIG. 19  in the locked position, and the dashed lines indicate where the first and second flanges  1906   a,b  may shift to when the latch  1904  is pivoted to the released position. 
     The latch  1904  may be naturally biased to the locked position. In some embodiments, for example, the rack locking assembly  1900  may further include a compression spring or other deformable elastic member  1910  engageable against the latch  1904  and configured to continuously urge the latch  1904  to the locked position. As will be appreciated, the compression spring  1910  may be replaced with any other type of passive biasing element such as, but not limited to, a torsion spring included at the pivot point of the latch  1904 . Actuating the shifting mechanism  1828  ( FIGS. 18A-18B ), as described above, may apply tension on the drive cable  1834 , which will pull distally (i.e., down in  FIG. 19 ) on the latch  1904 . The applied tension may overcome the spring force of the compression spring  1910 , which will cause the latch  1904  to pivot to the unlocked position and thereby dislodge the first and second flanges  1906   a,b  from the downstop and upstop recesses  1908   a,b,  respectively. Actuating the shifting mechanism  1828  in the opposite direction, however, will remove the tension from the drive cable  1834  and thereby allow the latch  1904  to naturally move back to the locked position under the spring force of the compression spring  1910 . 
     When the actuation system  1800  ( FIG. 18 ) is in the first configuration, the latch  1904  will be in the locked position, thus locking the rack  1804  to the shaft  1602 . In the locked position, driving the rack  1804  via rotation of the pinion gear  1822  ( FIG. 18A ), as described above, will move the entire shaft  1602  relative to the handle  1614  ( FIGS. 18A-18B ) in z-axis translation. In contrast, transitioning the actuation system  1800  to the second configuration will correspondingly pivot the latch  1904  to the released position, thus releasing the rack  1804  from the shaft  1602 . In the released position, driving the rack  1804  via rotation of the pinion gear  1822  will cause the rack  1804  to move independent of the shaft  1602  and advance or retract a knife arranged at the end effector  1604  ( FIG. 16 ). After firing the knife, retracting the rack  1804  proximally will allow the latch  1904  to reengage the rack  1804  and thereby revert back to the locked position. In some embodiments, as illustrated, the proximal end of the rack  1804  may provide or otherwise define a tapered edge  1912 , which may prove advantageous in guiding the spring-biased second flange  1906   b  into engagement with the upstop recess  1908   b  as the rack  1804  moves proximally. 
     Referring again to  FIGS. 18A-18B , the actuation system  1800  may further include a second drive shaft or “capstan”  1808   b  coupled to or forming part of the first drive input  1620   a  such that rotation of the first drive input  1620   a  correspondingly rotates the second capstan  1808   b  in the same direction. A second helical drive gear  1810   b  ( FIG. 18A ) is coupled to or forms part of the second capstan  1808   b  and rotates as the second capstan  1808   b  rotates. In some embodiments, the second helical drive gear  1810   b  may intermesh with and drive the gear train  1812  (best seen in  FIG. 18A ) when the actuation system  1800  is transitioned to the second configuration. Accordingly, rotation (actuation) of the second capstan  1808   b  may correspondingly drive the rack  1804  via the gear train  1812  when the actuation system  1800  is in the second configuration. 
     More specifically, the gear train  1812  may further include a second helical driven gear  1814   b  ( FIG. 18A ) mounted to the first axle  1824   a  and driven by the second helical drive gear  1810   b.  In some embodiments, as the shifting mechanism  1828  transitions the actuation system  1800  from the first configuration to the second configuration, the clutch  1826  (best seen in  FIG. 18A ) may be simultaneously moved laterally to disengage the first clutch interface  1827   a  between the spur drive gear  1818  and the first helical driven gear  1814   a.  The clutch  1826  may instead be moved laterally to engage a second clutch interface  1827   b  formed between the spur drive gear  1818  and the second helical driven gear  1814   b,  and thereby engaging the gear train  1812  with the second helical driven gear  1814   b.  The clutch  1826  is depicted as a type of “dog clutch,” but could alternatively comprise a type of friction clutch, without departing from the scope of the disclosure. 
     As illustrated, the clutch  1826  may be mounted to and laterally movable along the first axle  1824   a.  More specifically, the clutch  1826  may include a spool  1846  engageable with a pin  1848  provided by the armature  1830 . As the shifting mechanism  1828  transitions from the first configuration to the second configuration, the armature  1830  will correspondingly move the pin  1848  laterally, which will urge the clutch  1826  in the same lateral direction as engaged with the spool  1846 . Moving the clutch  1826  laterally will disengage the first clutch interface  1827   a  at the first helical driven gear  1814   a,  and instead engage the second clutch interface  1827   b  at the second helical driven gear  1814   b.  As will be appreciated, transitioning the actuation system  1800  back to the first configuration will correspondingly cause the clutch  1826  to disengage the second clutch interface  1827   b  and instead re-engage the first clutch interface  1827   a.    
     Accordingly, when the actuation system  1800  is in the first configuration, as is depicted in  FIGS. 18A-18B , the first clutch interface  1827   a  will be engaged, thus allowing the first helical driven gear  1814   a  to drive the spur drive gear  1818 , which ultimately drives the pinion gear  1822  against the rack  1804 . In contrast, and in at least one embodiment, when the actuation system  1800  is transitioned to the second configuration and the clutch  1826  is correspondingly shifted laterally to engage the second clutch interface  1827   b,  the second helical driven gear  1814   b  may drive the spur drive gear  1818 , ultimately drives the pinion gear  1822  against the rack  1804 . As indicated above, the latch  1904  ( FIG. 19 ) may be in the locked position when the actuation system  1800  is in the first configuration, thus locking the rack  1804  to the shaft  1602 . Consequently, actuating the third drive input  1620   c  when the actuation system  1800  is in the first configuration will move the entire shaft  1602  relative to the handle  1614  in z-axis translation. In contrast, transitioning the actuation system  1800  to the second configuration will pivot the latch  1904  to the released position and simultaneously shift the clutch  1826  laterally to engage the second helical driven gear  1814   b.  In this position, actuating the first drive input  1620   a  will cause the rack  1804  to move independent of the shaft  1602  and advance or retract a knife arranged at the end effector  1604  ( FIG. 16 ). 
     Accordingly, actuation of the second drive input  1620   b  may transition the actuation system  1800  between the first and second configurations. In some embodiments, as discussed above, the third drive input  1620   c  may be actuatable to drive the rack  1804  for z-axis translation when the actuation system  1800  is in the first configuration, and may further be actuatable to drive the rack  1804  independent of the shaft  1602  for knife firing when the actuation system  1800  is in the second configuration. In other embodiments, however, such as in embodiments that include the clutch  1826 , the third drive input  1620   c  may be actuatable to drive the rack  1804  for z-axis translation when the actuation system  1800  is in the first configuration, but the first drive input  1620   a  may be actuatable to drive the rack  1804  independent of the shaft  1602  for knife firing. Incorporating the use of both the first and third drive inputs  1620   a,c  may prove advantageous in incorporating differing engineered gear ratios, thus resulting in differing torque outputs for z-axis translation and knife firing. For example, a lower gear ratio with lower torque may be advantageous for z-axis translation, but a higher gear ratio (e.g., a higher reduction gear train) with more torque may be more appropriate for knife firing. This allows for the use of smaller motors as opposed to a larger motor having sufficient speed and torque to satisfy z-axis insertion speed and knife firing torque requirement. Using smaller motors reduces the mass located near the end of surgical robotic arm, increasing the dynamic response of a given robotic arm. Use of two smaller motors is also advantageous from a thermodynamics standpoint, as smaller motors produce less torque and require less current, thus resulting in less ohmic heating inside the motor. Moreover, smaller motors have less rotational inertia, therefor smaller motors will impart smaller moments to the robotic arm during acceleration or deceleration of said motors. 
       FIG. 20  is an isometric side view of one example of the rack  1804  operatively coupled to a knife  2002 , according to one or more embodiments. As illustrated, a distal end  2004  of the rack  1804  may be coupled to a firing rod  2006  that extends distally therefrom. The knife  2002  may be coupled to the distal end of the firing rod  2006 . In the illustrated embodiment, the rack  1804  is indirectly coupled to the knife  2002  via the firing rod  2006 . In other embodiments, however, the rack  1804  may be directly coupled to the knife  2002 , without departing from the scope of the disclosure. In either scenario, distal or proximal movement of the rack  1804 , as described above, will correspondingly move the knife  2002  in the same direction. 
       FIG. 21  is an enlarged cross-sectional side view of the end effector  1604 , according to one or more embodiments. As mentioned above, the actuation system  1800  ( FIGS. 18A-18B ) may be operable to cause the end effector  1604  to “fire” when in the second configuration. More specifically, the knife  2002  may be arranged at the end effector  1604 , and operation of the actuation system  1800  in the second configuration may cause the knife  2002  to be linearly displaced within the guide track  1616  to cut tissue grasped between the jaws  1610 ,  1612 . The knife  2002  may be operatively coupled to the firing rod  2006 , as discussed with reference to  FIG. 20 , which extends proximally (i.e., to the right in  FIG. 21 ) from the knife  2002  to be coupled to the distal end  2004  ( FIG. 20 ) of the rack  1804  ( FIG. 20 ). Driving the rack  1804 , as discussed herein causes the firing rod  2106  to linearly advance and retract and correspondingly advance and retract the knife  2002  within the guide track  1616 . 
     In embodiments where the end effector  1604  comprises a surgical stapler, distally advancing the knife  2002  within the guide track  1616  may simultaneously advance a sled or camming wedge  2004 , which engages a plurality of staples (not shown) contained within the lower jaw  1610  (e.g., within a staple cartridge) and urges (cams) the staples into deforming contact with the opposing anvil surfaces (e.g., pockets) provided on the upper jaw  1612 . Properly deployed staples help seal opposing sides of the transected tissue. 
       FIG. 22  is another isometric view of the handle  1614  and the actuation system  1800  from an alternative perspective, according to one or more embodiments of the present disclosure. Again, the outer body of the handle  1614  is shown in phantom (dashed lines) to enable viewing of the internal space within the handle  1614 , including the actuation system  1800 . Various other actuation systems and component parts of the handle  1614  are omitted in  FIG. 22  for simplicity. 
     In some embodiments, the actuation system  1800  may further include a shaft locking mechanism  2202  operatively coupled to the fourth drive input  1620   d  such that actuation (rotation) of the fourth drive input  1620   d  may operate the shaft locking mechanism  2202  to lock and unlock z-axis translation of the shaft  1602 . As illustrated, the shaft locking mechanism  2202  may include first and second caliper actuating arms  2204   a  and  2204   b  pivotably coupled to each other at a first end  2206   a  and engageable with the fourth drive input  1620   d  at a second end  2206   b.  At least a portion of each caliper actuating arm  2204   a,b  may be curved (arcuate) to allow the caliper actuating arms  2204   a,b  to extend around opposite sides of the shaft  1602 . In some embodiments, the first caliper actuation arm  2204   a  may define a groove  2208  configured to receive a portion of the second caliper actuating arm  2204   b  in a crossing and sliding engagement during operation. Receiving the second caliper actuating arm  2204   b  within the groove  2208  may help prevent the caliper actuating arms  2204   a,b  from separating during operation. 
     As illustrated, the second ends  2206   b  of the caliper actuating arms  2204   a,b  may be engageable with a cam feature  2210  coupled to or forming an integral extension of the fourth drive input  1620   d.  In the illustrated embodiment, the cam feature  2210  comprises an oblong or oval-shaped pin, but could alternatively comprise any other feature that provides a camming effect when rotated against an adjacent structure. The second ends  2206   b  of the caliper actuating arms  2204   a,b  are arranged on opposite sides of the cam feature  2210  such that rotation of the cam feature  2210 , as driven by stroke-limited actuation of the fourth drive input  1620   d,  will correspondingly force the second ends  2206   b  of the caliper actuating arms  2204   a,b  away from each other, as indicated by the arrows C. Because of the crossing configuration of the caliper actuating arms  2204   a,b,  forcing the second ends  2206   b  away from each other may simultaneously force the caliper actuating arms  2204   a,b  radially inward, as indicated by the arrows D, and into lateral binding engagement with the shaft  1602 . Consequently, a friction-type lock is formed against the shaft  1602  by urging the caliper actuating arms  2204   a,b  into lateral engagement with the shaft  1602 , regardless of the z-axis position of the shaft  1602 . Upon reversing the actuation of the fourth drive input  1620   d,  the gripped engagement of the shaft  1602  with the caliper actuating arms  2204   a,b  will correspondingly be removed, thus allowing the shaft  1602  to freely translate. 
     Accordingly, actuating the fourth drive input  1620   d  may cause the shaft locking mechanism  2202  to mechanically lock and secure the shaft  1602  in place relative to the handle  1614  such that z-axis translation of the shaft  1602  is prevented. In some embodiments, the fourth drive input  1620   d  may be actuated when the actuation system  1800  is transitioned to the second configuration and poised to drive the rack  1804  ( FIGS. 18A and 19 ) independent of the shaft  1602  to advance or retract the knife  2002  ( FIGS. 20-21 ). In such embodiments, securing the shaft  1602  against z-axis translation may help prevent the shaft  1602  ( FIGS. 18A-18B ) from inadvertently advancing or retracting along with movement of the rack  1804 . 
     While the shaft locking mechanism  2202  is described and illustrated herein as including the first and second caliper actuating arms  2204   a,b  operable to move into lateral binding engagement with the shaft  1602  and thereby prevent the shaft  1602  from translating, those skilled in the art will readily appreciate that other designs and systems could equally be employed to lock the shaft  1602  inside the confines of the handle  1614 . In one embodiment, for example, a torsion spring may be included that grips the shaft  1602  and is either released or locked when acted on. In other embodiments, a cam lobe could acts directly on the shaft  1602  to stop its axial translation. In yet other embodiments, two thin steel tabs at equal but opposite angles may be included to arrest shaft  1602  motion in both directions and be actuated to release. Accordingly, the shaft locking mechanism  2202  may generally comprise a mechanism in the handle  1614  that acts on the shaft  1602  to arrest axial motion, and that may be released or engaged when acted upon by a particular drive input. 
     Logic for a Transmission Rack-Based Architecture 
     Referring now to  FIG. 23 , and with continued reference to the actuation system  1800  described in  FIGS. 18A-18B, 19, and 22 , illustrated are interconnected logic diagrams for operating the surgical tool  1600  of  FIGS. 16-17 . More specifically, the logic diagrams depict example operational conditions for operating the handle  1614  and the actuation system  1800  in various conditions, as described herein and in accordance with one or more embodiments. 
     Referring first to the first logic diagram  2300   a,  depicted are logic and operational conditions for shaft insertion; e.g., z-axis translation of the shaft  1602 . To effectively accomplish z-axis translation of the shaft  1602 , the latch  1904  is pivoted to the locked position, and thereby securing the rack  1804  to the shaft, as at  2302 . The fourth drive input  1620   d  is also actuated or otherwise disabled to release the shaft locking mechanism  2202  from the shaft  1602 , as at  2304 , and thereby freeing the shaft  1602  for z-axis translation. The drive input operable to cause firing of the knife  2002  is also disabled, as at  2306 . In some embodiments, as discussed above, this may refer to disabling the third drive input  1620   b,  which is actuatable to drive the rack  1804  and thereby move the knife  2002 . In contrast, the drive input operable to cause translation of the shaft  1602  is enabled, as at  2308 . As discussed above, the second drive input  1620   b  may be configured and otherwise actuatable to cause translation of the shaft  1602 . During shaft translation, it may also be desired to allow articulation of the end effector  1604  ( FIG. 16 ) and actuation (e.g., opening and closing) of the jaws  1610 ,  1612  ( FIGS. 16-17 ). Accordingly, the first logic diagram  2300   a  may further include enabling the drive input operable to cause articulation of the end effector  1604 , as at  2310 , and enabling the drive input operable to open and close the jaws  1610 ,  1612 , as at  2312 . As described herein, in at least one embodiment, the fifth drive input  1620   e  ( FIGS. 16-17 ) may be actuatable to cause articulation of the end effector  1604 , and the sixth drive input  1620   f  ( FIGS. 16-17 ) may be actuatable to cause the jaws  1610 ,  1612  to open or close. 
     Referring to the second logic diagram  2300   b,  depicted are logic and operational conditions for when a desired shaft insertion position is reached. Once a desired position of the shaft  1602  is reached, the latch  1904  will remain in the locked position, as at  2314 , but the fourth drive input  1620   d  will be actuated to enable the shaft locking mechanism  2202 , as at  2316 , and thereby secure the shaft  1602  against further z-axis translation. The drive input operable to cause firing of the knife  2002  also remains disabled, as at  2318 , and the drive input operable to cause translation of the shaft  1602  is disabled, as at  2320 . Once shaft insertion has stopped, however, it may still be desired to allow articulation of the end effector  1604  ( FIG. 16 ) and actuation (e.g., opening and closing) of the jaws  1610 ,  1612  ( FIGS. 16-17 ). Accordingly, the second logic diagram  2300   b  may further include maintaining enabled the drive input operable to cause articulation of the end effector  1604 , as at  2322 , and maintaining enabled the drive input operable to open and close the jaws  1610 ,  1612 , as at  2324 . 
     Referring to the third logic diagram  2300   c,  depicted are logic and operational conditions for jaw closure and transition to firing. To enable closure of the jaws  1610 ,  1612  ( FIGS. 16-17 ) and to prepare the end effector  1604  ( FIG. 16 ) for firing, the latch  1904  will be moved to the unlocked position, as at  2326 , but the shaft locking mechanism  2202  will remain enabled to continue to prevent z-axis translation of the shaft  1602 , as at  2328 . The drive input operable to cause firing of the knife  2002  also remains disabled at this point, as at  2330 , and the drive input operable to cause translation of the shaft  1602  remains disabled, as at  2332 . Since it may still be desired to allow articulation of the end effector  1604  ( FIG. 16 ) and actuation (e.g., opening and closing) of the jaws  1610 ,  1612  ( FIGS. 16-17 ), the drive input operable to cause articulation of the end effector  1604  will remain enabled, as at  2334 , and the drive input operable to open and close the jaws  1610 ,  1612  will also remain enabled, as at  2336 . 
     Referring to the fourth logic diagram  2300   d,  depicted are logic and operational conditions for the firing and return of the knife  2002 . To enable firing of the knife  2002 , the latch  1904  will remain in the unlocked position, as at  2338 , but will be transitioned back to the locked position upon return of the knife  2002  and otherwise following the firing process. The shaft locking mechanism  2202  will also remain enabled during knife  2002  firing, as at  2340 , to continue to prevent inadvertent translation of the shaft  1602  during firing. The drive input operable to cause firing of the knife  2002  is now enabled, as at  2342 , and the drive input operable to cause translation of the shaft  1602  remains disabled, as at  2344 . While the knife  2002  fires there is generally no need to articulate the end effector  1604  ( FIG. 16 ) or actuate (e.g., open and close) the jaws  1610 ,  1612  ( FIGS. 16-17 ). Consequently, the drive input operable to cause articulation of the end effector  1604  will be disabled, as at  2346 , and the drive input operable to open and close the jaws  1610 ,  1612  will also be disabled, as at  2348 . 
     The directional arrows extending between the logic diagrams  2300   a - d  indicate the order in which the instrument is able to move from one state to another. For example, some states may not be permitted transition to any other state, without first passing through an intermediate state. 
     Outer Tube Device Function Compensation 
     Referring to  FIG. 24 , with continued reference to the actuation system  1800  described in  FIGS. 18A-18B, 19, and 22 , depicted is an enlarged view of the end effector  1604  and the wrist  1606 , according to one or more embodiments. As illustrated, the wrist  1606  may include a first or “proximal” clevis  2402   a,  a second or “distal” clevis  2402   b,  and a closure link  2404  configured to operatively couple the proximal and distal devises  2402   a,b  across the wrist  1606 . The proximal clevis  2402   a  may be coupled to or otherwise form part of the distal end of the shaft  1602  and, more particularly, the distal end of a closure tube  2406  that forms an outer portion of the shaft  1602 . The distal clevis  2402   b  may be coupled to or otherwise form part of a closure ring  2408 . 
     In some embodiments, axial movement of the closure tube  2406  along the longitudinal axis A l  may cause the jaws  1610 ,  1612  of the end effector  1604  to close or open, depending on the longitudinal direction of the closure tube  2406 . More specifically, movement of the closure tube  2406  will act on the proximal clevis  2402   a  in the same axial direction, and the closure link  2404  is configured to transmit the axial load through (across) the wrist  1606  to close or open the jaws  1610 ,  1612 . The closure link  2404  may define a pair of protrusions  2410  configured to mate with corresponding apertures  2412  defined in each of the proximal and distal clevises  2402   a,b.  The closure link  2404  may transmit the closure load or translation of the closure tube  2406  from the distal clevis  2402   b  to the proximal clevis  2402   a  and the closure ring  2408  will correspondingly push or pull on the upper jaw  1612  to open or close the upper jaw  1612 . To close the upper jaw  1612 , the closure ring  2408  is forced against a shoulder  2414  at or near the back of the upper jaw  1612 , which urges the upper jaw  1612  to pivot down and to the closed position. To open the upper jaw  1612 , the closure ring  2408  is retracted proximally by retracting the closure tube  2406 , and the closure ring  2408  helps pull the upper jaw  1612  back toward the open position. Alternatively, the upper jaw  1612  may be spring loaded and biased to the open position, and retracting the closure ring  2408  removes loading on the shoulder  2414 , which allows the spring force to move the upper jaw  1612  to the open position. 
     In some embodiments, the closure tube  2406  may be advanced or retracted along the longitudinal axis A 1  using an actuation system provided in the handle  1614 . In such embodiments, for example, the actuation system may include a drive gear engageable with gear teeth provided on the outer surface of the closure tube  2406 . Actuating the actuation system will urge the drive gear against the gear teeth of the closure tube  2406  and thereby advance or retract the closure tube  2406  to close or open the jaws  1610 ,  1612 , depending on the movement of the closure tube  2406 . Based on the translate and pivot mechanism provided by interaction between the proximal and distal devises  2402   a,b  and the closure ring  2408 , as the closure tube  2406  advances to close the jaws  1610 ,  1612 , the jaws  1610 ,  1612  will simultaneously advance distally. In some applications, however, advancing the jaws  1610 ,  1612  distally while closing may not be desired and could be dangerous. For example, when the distal tip of the jaws  1610 ,  1612  is juxtaposed against an internal organ or vessel of the patient, further distal movement of the jaws  1610 ,  1612  may cause damage to the organ or vessel. 
     According to embodiments of the present disclosure, as the closure tube  2406  advances to close the jaws  1610 ,  1612 , the entire shaft  1602  may be simultaneously drawn proximally such that any forward movement of the jaws  1610 ,  1612  during closure is offset or counteracted by a corresponding equal movement of the shaft  1602  in the opposite direction. For example, when the actuation system is actuated to move the closure tube  2406 , the actuation system  1800  of  FIGS. 18A-18B  may be simultaneously actuated in the first configuration, where the rack  1804  is locked to the shaft  1602  such that driving the rack  1804  causes the entire shaft  1602  to move relative to the handle  1614 . In such embodiments, the actuation system  1800  may be operated to move the shaft  1602  proximally to cancel out any distal movement of the jaws  1610 ,  1612 . Furthermore, as the closure tube  2406  retracts proximally to open the jaws  1610 ,  1612 , the actuation system  1800  may be simultaneously operated to move the shaft  1602  distally such that any proximal movement of the jaws  1610 ,  1612  during opening is offset or counteracted by a corresponding equal movement of the shaft  1602  in the opposite direction. As will be appreciated, this may help ensure that the distal tip of the end effector  1604  remains stationary during closure and opening. 
     Asymmetric Gear Drive Affecting Knife without Software Decoupling 
       FIG. 25  is an enlarged schematic side view of another embodiment of the handle  1614  of  FIGS. 16-17 , according to one or more embodiments of the present disclosure. The outer body of the handle  1614  is again shown in phantom (dashed lines) to enable viewing of the internal space and components within the handle  1614 . Various actuation systems and component parts of the handle  1614  are omitted in  FIG. 25  for simplicity. 
     The shaft  1602  extends through the handle  1614  and may again include the outer shaft portion  1802  and the rack  1804  at least partially received within the longitudinal channel  1806  defined in the outer shaft portion  1802 . Alternatively, the rack  1804  may be arranged outside of the longitudinal channel  1806  or otherwise extend along the exterior of the shaft  1602 , without departing from the scope of the disclosure. The rack  1804  may be driven longitudinally relative to the shaft  1602  by engaging gear teeth defined along at least a portion of its longitudinal length. As mentioned above and discussed in more detail below, the rack  1804  may be operatively coupled to the knife  2002  ( FIG. 20 ) arranged at the end effector  1604  ( FIG. 16 ). Consequently, driving the rack  1804  may cause the knife  2002  to advance or retract at the end effector  1604 . 
     As illustrated, the handle  1614  may include a first actuation system  2502   a  and a second actuation system  2502   b.  The actuation systems  2502   a,b  may be operable (actuatable) to carry out a variety of functions (operations) of the surgical tool  1600  ( FIG. 16 ). In the illustrated embodiment, for example, the first actuation system  2502   a  may be designed and otherwise configured to “fire” the end effector  1604  ( FIG. 16 ), which advances or retracts the knife  2002  ( FIG. 20 ) arranged at the end effector  1604 . Moreover, the second actuation system  2502   b  may be operable to cause the shaft  1602  (including the rack  1804 ) to move relative to the handle  1614  and thereby longitudinally advance or retract the end effector  1604  in z-axis translation. 
     The first actuation system  2502   a  includes a first drive shaft  2504   a  coupled to or forming part of a first drive input  2506   a  such that rotation of the first drive input  2506   a  correspondingly rotates the first drive shaft  2504   a  in the same direction. The first drive input  2506   a  may be the same as or similar to any of the drive inputs  1620   a - f  of  FIGS. 16-17  and, therefore, may be matable with any of the drive outputs  1718   a - f  ( FIG. 17 ) of the instrument driver  1618  ( FIGS. 16-17 ) for actuation (rotation). Rotating the first drive input  2506   a  may operate or actuate a drive mechanism  2508  that may include any of a variety of interconnected gears, belts, chains, sprockets, etc. configured to ultimately drive the rack  1804 . In the illustrated embodiment, the drive mechanism  2508  comprises a type of gear train that includes one or more interconnected (or intermeshed) gears configured to ultimately intermesh with and drive the rack  1804 . Accordingly, rotation (actuation) of the first drive shaft  2504   a  may correspondingly drive the rack  1804  and fire the end effector  1604  ( FIG. 16 ) via operation of the drive mechanism  2508 . 
     In the illustrated embodiment, the drive mechanism  2508  includes a beveled drive gear  2510 , a beveled driven gear  2512 , and an asymmetric pinion or “sector” gear  2514 . The beveled drive gear  2510  intermeshes with and is otherwise arranged to drive the beveled driven gear  2512 . The beveled drive gear  2510  is coupled to or forms part of the first drive shaft  2504   a  such that rotating the first drive shaft  2504   a  correspondingly rotates the beveled driven gear  2512 . Moreover, the sector gear  2514  may be coupled to the beveled driven gear  2512  such that rotating the beveled driven gear  2512  correspondingly rotates the sector gear  2514 . Accordingly, actuation of the first actuation system  2502   a  causes the sector gear  2514  to engage and drive the rack  1804 , which may advance or retract the knife  2002  ( FIG. 20 ) operatively coupled to the end of the rack  1804  and arranged at the end effector  1604  ( FIG. 16 ). 
     The sector gear  2514  may be similar in some respects to the pinion gear  1822  of  FIG. 18A  and, therefore, may include gear teeth capable of intermeshing with the gear teeth of the rack  1804 . Accordingly, selective rotation of the sector gear  2514  may drive the rack  1804  proximally or distally, depending on rotation direction. As described in more detail below, however, the gear teeth may not extend about the entire circumference of the sector gear  2514 . Instead, no gear teeth may be provided along a contiguous arcuate length of the sector gear  2514 . Accordingly, the sector gear  2514  may be referred to herein as “asymmetric” since its gear teeth are asymmetrically provided about the outer circumference of the gear. 
     While the drive mechanism  2508  depicted in  FIG. 25  includes three geared components, those skilled in the art will readily appreciate that the drive mechanism  2508  may alternatively include more or less than three geared components to drive the rack  1804 . Indeed, the depicted drive mechanism  2508  is but one example of a geared system or arrangement designed to drive the rack  1804 , and various other designs or configurations of the drive mechanism  2508  may alternatively be incorporated into the first actuation system  2502   a,  without departing from the scope of the disclosure. 
     The second actuation system  2502   b  includes a second drive shaft  2504   b  coupled to or forming part of a second drive input  2506   b  such that rotation of the second drive input  2506   b  correspondingly rotates the second drive shaft  2504   b  in the same direction. As with the first drive input  2506   a,  the second drive input  2506   b  may be the same as or similar to any of the drive inputs  1620   a - f  of  FIGS. 16-17  and, therefore, may be matable with any of the drive outputs  1718   a - f  ( FIG. 17 ) of the instrument driver  1618  ( FIGS. 16-17 ) for actuation (rotation). Operating the second actuation system  2502   b,  and thereby rotating the second drive input  2506   b,  may cause the shaft  1602  (including the rack  1804 ) to move relative to the handle  1614  and thereby longitudinally advance or retract the end effector  1604  in z-axis translation. 
     More specifically, as illustrated, the second actuation system  2502   b  includes a spool  2516  coupled to or forming part of the second drive shaft  2504   b  such that rotating the second drive shaft  2504   b  correspondingly rotates the spool  2516  in the same angular direction. The second actuation system  2502   b  may further include first and second drive members  2518   a  and  2518   b  that extend longitudinally along at least a portion of the shaft  1602 . In the illustrated embodiment, the drive members  2518   a,b  comprise cables or wires and, therefore, will be referred to herein as “drive cables”. In other embodiments, however, the drive cables  2518   a,b  may comprise any of the other types of drive members mentioned herein. In some embodiments, the drive cables  2518   a,b  may be received and extend within corresponding grooves (not shown) defined in the shaft  1602 , but may alternatively be received within the interior of the shaft  1602  or extend along the exterior surface of the shaft  1602 , without departing from the scope of the disclosure. 
     As illustrated, the drive cables  2518   a,b  may each be wrapped around the spool  2516  one or more times. A first or “distal” end  2520   a  of the first drive cable  2518   a  may be anchored to the shaft  1602  below (distal to) the handle  1614  and at a distance sufficient to allow the shaft  1602  to translate relative to the handle  1614 . A second or “proximal” end  2520   b  of the first drive cable  2518   a  may be secured to the spool  2516 . In contrast, a first or “proximal” end  2522   a  of the second drive cable  2518   b  may be anchored to the shaft  1602  above (proximal to) the handle  1614  and at a distance sufficient to allow the shaft  1602  to translate relative to the handle  1614 . In at least one embodiment, the proximal end  2522   a  may be attached at or near a proximal end  2524  of the shaft  1602 . A second or “distal” end  2522   b  of the second drive cable  2518   a  may be secured to the spool  2516 . 
     The second actuation system  2502   b  may further include a first or “upper” idler pulley  2526   a  and a second or “lower” idler pulley  2526   b.  The upper and lower idler pulleys  2526   a,b  may each be rotatably coupled to the handle  1614 . The upper idler pulley  2526   a  may be arranged and otherwise configured to redirect the second drive cable  2518   b  between the shaft  1602  and the spool  2516 , and the lower idler pulley  2526   b  may be arranged and otherwise configured to redirect the first drive cable  2518   a  between the shaft  1602  and the spool  2516 . 
     In example operation of the second actuation system  2502   b,  rotation of the spool  2516  in a first angular direction (e.g., clockwise), via actuation of the second drive input  2506   b,  will correspondingly pay out (feed) the first drive cable  2518   a  from the spool  2516  to the shaft  1602 , while simultaneously paying in (drawing in) the second drive cable from the shaft  1602  to the spool  2516 . Since the distal end  2520   a  of the first drive cable  2518   a  is anchored to the shaft  1602  below the handle  1614 , and the proximal end  2522   a  of the second drive cable  2518   b  is anchored to the shaft  1602  above the handle  1614 , paying out the first drive cable  2518   a  while simultaneously paying in the second drive cable  2518   b  will cause the shaft  1602  to move distally relative to the handle  1614 , as indicated by the arrow E. In contrast, rotation of the spool  2516  in a second angular direction (e.g., counter-clockwise), opposite the first angular direction, will correspondingly pay in (draw in) the first drive cable  2518   a  from the shaft  1602  to the spool  2516 , while simultaneously paying out (feeding) the second drive cable from the spool  2516  to the shaft  1602 . Paying in the first drive cable  2518   a  while simultaneously paying out the second drive cable  2518   b  will cause the shaft  1602  to move proximally relative to the handle  1614 , as indicated by the arrow F. 
     Referring to the inset, enlarged side view of the sector gear  2514  in  FIG. 25 , a plurality of gear teeth  2528  may be defined about the outer periphery or circumference of the sector gear  2514 . The sector gear  2514 , however, may provide or otherwise define a tooth-free zone  2530 , which comprises a contiguous arcuate portion of the sector gear  2514  where no gear teeth  2528  are present or found. Accordingly, the sector gear  2514  includes gear teeth  2528  that are asymmetrically formed on the sector gear  2514  and otherwise provided on less than the entire outer circumference (e.g., less than 360°) of the sector gear  2514 . In at least one embodiment, the sector gear  2514  may have the same or different geometry of the gear teeth  2528  across the arcuate section of teeth. For example, in some embodiments, the first one or more gear teeth  2528  adjacent to each side of the tooth-free zone  2530  may have a different geometry as compared to the remaining gear teeth  2528  to aid in a smooth transition and engagement with the rack  1804  when the sector gear is rotated. 
     When the sector gear  2514  is rotated such that the tooth-free zone  2530  faces the rack  1804 , no gear teeth  2528  are able to engage the rack  1804 , thus effectively decoupling the shaft  1602  from the first actuation system  2502   a.  Decoupling the shaft  1602  from the first actuation system  2502   a  allows the shaft  1602  (and the rack  1804 ) to freely translate relative to the handle  1614  in z-axis translation without the sector gear  2514  binding against the rack  1804  and thereby preventing longitudinal movement. 
     When it is desired to advance or retract the end effector  1604  ( FIG. 16 ), the first actuation system  2502   a  may first be configured to rotate the sector gear  2514  such that the tooth-free zone  2530  faces the rack  1804 . The second actuation system  2502   b  may then be operated to freely move the shaft  1602  (and the rack  1804 ) in z-axis translation without the gear teeth  2528  of the sector gear  2514  engaging (binding against) the rack  1804  and thereby preventing movement of the shaft  1602 . In contrast, when it is desired to “fire” the end effector  1604  ( FIG. 16 ) and thereby advance or retract the knife  2002  ( FIG. 20 ) at the end effector  1604 , the first actuation system  2502   a  may be operated to rotate the sector gear  2514  until the gear teeth  2528  engage and drive the rack  1804 . If z-axis translation of the shaft  1602  is again desired, the first actuation system  2502   a  may again be actuated to rotate the sector gear  2514  such that the tooth-free zone  2530  again faces the rack  1804  and decouples the shaft  1602  from the first actuation system  2502   a.    
     In some embodiments, z-axis translation of the shaft  1602  may be locked by disabling the drive output motor operatively coupled to the second drive input  2506   b.  In other embodiments, or in addition thereto, z-axis translation of the shaft  1602  may be locked or otherwise prevented by engaging the gear teeth  2528  of the sector gear  2514  against the rack  1804 . In yet other embodiments, z-axis translation of the shaft  1602  may be prevented by the sector gear  2514  engaging or otherwise operating a lever-type lock (not illustrated). 
     Belt Shaft Insertion Drive and Sealing 
     When performing surgical procedures, such as laparoscopic procedures, surgeons commonly incorporate the use of insufflation, which entails introducing a fluid (e.g. carbon dioxide) into an inner cavity (e.g., the abdomen) of a patient to elevate the interior walls of the inner cavity. The fluid is introduced via one or more cannulas inserted into the patient&#39;s abdomen and the cannulas are commonly sealed against surgical tool shafts inserted therein to maintain positive pressure inside the patient&#39;s body. Various types of seals are used to prevent or minimize air leakage from the patient&#39;s body via the tool shafts and thereby achieve a pneumatic seal. These seals, however, are typically designed to accommodate tool shafts with round cross-sections, but it can be difficult to apply the same types of seals to non-circular tool shafts. In particular, pneumatic shaft seals designed to prevent loss of insufflation pressure may be required when using a cable-based architecture compatible with the z-axis insertion, as generally described herein. Seals and seal systems are needed to seal the irregularly-shaped shaft  1602 , which may include one or more longitudinal passages or grooves that accommodate various drive members or other structural components. 
       FIG. 26  is an enlarged isometric view of another embodiment of the handle  1614  of  FIGS. 16-17 , according to one or more embodiments of the present disclosure. The outer body of the handle  1614  is again shown in phantom (dashed lines) to enable viewing of the internal space and components within the handle  1614 . Moreover, various actuation systems and component parts of the handle  1614  are omitted in  FIG. 26  for simplicity. 
     The shaft  1602  extends through the handle  1614  and may again include the outer shaft portion  1802  and the rack  1804  at least partially received within the longitudinal channel  1806  defined in the outer shaft portion  1802 . As described herein, the rack  1804  defines a series of teeth engageable by corresponding gear teeth of a pinion gear, such as the pinion gear  1822 . While not depicted in  FIG. 26 , the pinion gear  1822  may form part of an actuation system designed to rotate the pinion gear  1822  and thereby drive the rack  1804 . In at least one embodiment, for example, the pinion gear  1822  may form part of the actuation system  1800  of  FIGS. 18A-18B , as described above, but the pinion gear  1822  may alternatively be incorporated into any other actuation system capable of rotating the pinion gear  1822  to drive the rack  1804 . Driving the rack  1804 , as discussed herein, may cause the entire shaft  1602  to move relative to the handle  1614  in z-axis translation, or may alternatively cause the rack  1804  to move independent of the shaft  1602  and thereby “fire” the end effector  1604  ( FIG. 16 ) arranged at the distal end of the shaft  1602 . 
     The channel  1806  that receives the rack  1804  presents a potential leak path for insufflation pressure to escape from the shaft  1602 . To help ensure effective insufflation during operation and otherwise mitigate pressure loss through the shaft  1602 , a seal system  2602  may be included in the handle  1614 . As illustrated, the seal system  2602  can include a rack seal  2604  that extends along all or a portion of the shaft  1602 . The rack seal  2604  is received within the channel  1806  to substantially seal the channel  1806 . In the illustrated embodiment, the rack seal  2604  is in the form of an elongate belt that may be made of a compliant material capable of forming a sealed interface such as, but not limited to, an elastomer (e.g., rubber), a plastic, a composite material, or a metal (e.g., thin spring steel). In other embodiments, however, the rack seal  2604  may comprise another type of sealing device or configuration configured to substantially seal along the channel  1806 . 
     In the illustrated embodiment, a distal end of the rack seal  2604  may be anchored to the shaft  1602  at a point distal to the handle  1614 , and a proximal end of the rack seal  2604  may be anchored to the shaft  1602  at a point proximal to the handle  1614 . As will be appreciated, the distal and proximal ends of the rack seal  2604  may be anchored at distances sufficient to allow the shaft  1602  to translate relative to the handle  1614 , as described herein. A bottom surface  2606   a  of the rack seal  2604  will face the gear teeth of the rack  1804  when the rack seal  2604  is received within the channel  1806 . In some embodiments, the bottom surface  2606   a  may be flat, but could alternatively exhibit an arcuate (widthwise) or undulating shape, without departing from the scope of the disclosure. In at least one embodiment, the bottom surface  2606   a  may define gear teeth engageable with the gear teeth of the rack  1804 , as in more detail discussed below. 
     When the rack seal  2604  is received within the channel  1806 , a top surface  2606   b  of the rack seal  2604  may be generally aligned with the outer surface of the shaft  1602 . In such embodiments, the rack seal  2604  may be received within the channel  1806  and the top surface  2606   b  may form a flush-fit engagement with the outer surface of the shaft  1602 . In some embodiments, for example, the top surface  2606   b  may be curved, arcuate, or otherwise shaped to match the curvature of the outer surface of the shaft  1602 . Such curvature of the top surface  2606   b  may prove advantageous in allowing the shaft  1602  to be sealed above and below the handle  1614  and across the width of the rack seal  2604 . 
     Within the handle  1614 , various rollers may be arranged to redirect the rack seal  2604  out of the channel  1806  and thereby expose the rack  1804  to enable the pinion gear  1822  to interact with the rack  1804 . In the illustrated embodiment, for example, the seal system  2602  may further include a first or “upper” idler roller  2608   a,  a second or “lower” idler roller  2608   b,  and a redirect roller  2610  interposing the idler rollers  2608   a,b.  The rollers  2608   a,b,    2610  may each be rotatably coupled to the handle  1614  and sized to receive and redirect the rack seal  2604 . More specifically, the idler rollers  2608   a,b  may be arranged and otherwise configured to redirect the rack seal  2604  from the shaft  1602  to the redirect roller  2610  at or near the exit points of the shaft  1602  from the handle  1614 . The redirect roller  2610  may be positioned away from the shaft  1602  to expose the rack  1804  for driving. Importantly, however, the idler rollers  2608   a,b  may also be configured to redirect the rack seal  2604  back to the shaft  1602  at or near the exit points of the shaft  1602  from the handle  1614 , and in doing so may help press the rack seal  2604  against the rack  1804  and thereby generate a sealed interface at the channel  1806 . Accordingly, as the shaft  1602  translates relative to the handle  1614 , the rack seal  2604  is continuously fed through the rollers  2608   a,b,    2610  within the handle  1614  and back to the shaft  1602  to provide a sealed interface at the channel  1806 . 
     Because the rack  1804  is exposed within the handle  1614 , insufflation pressure may escape the shaft  1602  and feed into the handle  1614 . To prevent loss of insufflation pressure to the surrounding environment, the handle  1614  may be at least partially sealed. In one or more embodiments, for example, a first or “upper” dynamic seal  2612   a  may be coupled to the handle  1614  at or near a first or “proximal” end  2614   a  of the handle  1614 , and a second or “lower” dynamic seal  2612   b  may be coupled to the handle  1614  at or near a second or “distal” end  2614   b  of the handle  1614 . The dynamic seals  2612   a,b  may be configured to seal corresponding interfaces between the handle  1614  and the shaft  1602  at the ends  2614   a,b  of the handle  1614 , and otherwise at or near the exit points of the shaft  1602  from the handle  1614 . Because of the flush-fit seating of the rack seal  2604  within the channel  1806 , the seals  2612  may also be configured to seal against the top surface  2606   b  of the rack seal  2604 . Moreover, the dynamic seals  2612   a,b  may also be configured to provide a sealed interface during z-axis translation as the shaft  1602 . In at least one embodiment, for example, the dynamic seals  2612   a,b  may comprise lubricated O-rings or another material that allows near frictionless translation. 
       FIG. 27  is an enlarged side schematic view of another embodiment of the handle  1614  of  FIGS. 16-17 , according to one or more additional embodiments of the present disclosure. The outer body of the handle  1614  is again shown in phantom (dashed lines) to enable viewing of the internal space and components within the handle  1614 . Moreover, various actuation systems and component parts of the handle  1614  are omitted in  FIG. 27  for simplicity. 
     The shaft  1602  extends through the handle  1614  and may be configured to move relative to the handle  1614  in z-axis translation. In the present embodiment, however, moving the shaft  1602  relative to the handle  1614  may be accomplished using one or more drive belts  2702   a  and  2702   b  that extend along all or a portion of the shaft  1602 . In the illustrated embodiment, two drive belts  2702   a,b  are depicted and included on opposite sides of the shaft  1602 . Having at least two drive belts  2702   a,b  may help balance loading across the shaft  1602 . Those skilled in the art, however, will readily appreciate that more or less than two drive belts  2702   a,b  may be incorporated, without departing from the scope of the disclosure. 
     As illustrated, each drive belt  2702   a,b  may have a first or “proximal” end  2704   a  anchored to the shaft  1602  above (proximal to) the handle  1614  and at a distance sufficient to allow the shaft  1602  to translate relative to the handle  1614 . In at least one embodiment, the proximal ends  2704   a  may be attached at or near a proximal end  2706  of the shaft  1602 . A second or “distal” end  2704   b  of each drive belt  2702   a,b  may be anchored to the shaft  1602  below (distal to) the handle  1614  and at a distance sufficient to allow the shaft  1602  to translate relative to the handle  1614 . 
     The handle  1614  may include first and second actuation systems  2708   a  and  2708   b  operable (actuatable) to cause the shaft  1602  to move relative to the handle  1614  and thereby longitudinally advance or retract the end effector  1604  ( FIG. 16 ) in z-axis translation. As illustrated, the first actuation system  2708   a  includes a first drive shaft  2710   a  coupled to or forming part of a first drive input  2712   a  such that rotation of the first drive input  2712   a  correspondingly rotates the first drive shaft  2710   a  in the same direction. Similarly, the second actuation system  2708   b  includes a second drive shaft  2710   b  coupled to or forming part of a second drive input  2712   b  such that rotation of the second drive input  2712   b  correspondingly rotates the second drive shaft  2710   b  in the same direction. The drive inputs  2712   a,b  may be the same as or similar to any of the drive inputs  1620   a - f  of  FIGS. 16-17  and, therefore, may be matable with any of the drive outputs  1718   a - f  ( FIG. 17 ) of the instrument driver  1618  ( FIGS. 16-17 ) for actuation (rotation). 
     As illustrated, the first actuation system  2708   a  includes a first drive gear  2714   a  and the second actuation system  2708   b  includes a second drive gear  2714   b.  The first drive belt  2702   a  interacts with (e.g., extends around) the first drive gear  2714   a  such that rotating the first drive input  2712   a  causes the first drive gear  2714   a  to rotate and thereby drives the first drive belt  2702   a.  Similarly, the second drive belt  2702   b  interacts with (e.g., extends around) the second drive gear  2714   b  such that rotating the second drive input  2712   b  causes the second drive gear  2714   b  to rotate and thereby drives the second drive belt  2702   b.  Each actuation system  2708   a,b  may also include a first or “upper” idler roller  2716   a  and a second or “lower” idler roller  2716   b.  The idler rollers  2716   a,b  may be rotatably coupled to the handle  1614  and sized to receive and redirect the corresponding drive belts  2702   a,b  from the shaft  1602 , to the respective drive gear  2714   a,b,  and back to the shaft  1602 . In some embodiments, the idler rollers  2716   a,b  be arranged within the handle  1614  at or near the exit points of the shaft  1602  from the handle  1614  to help hold the drive belts  2702   a,b  against the shaft  1602 . 
     In example operation, according to at least one embodiment, the actuation systems  2708   a,b  may be operated to drive the corresponding drive gears  2714   a,b  in rotation. As the drive gears  2714   a,b  rotate, the respective drive belts  2702   a,b  are continuously fed through the idler rollers  2716   a,b  and along the length of the shaft  1602 . Since the drive belts  2702   a,b  are anchored to the shaft  1602  at proximal and distal ends  2704   a,b,  movement of the drive belts  2702   a,b  through the drive gears  2714   a,b  will cause the shaft  1602  to move relative to the handle  1614  in z-axis translation. As will be appreciated, the shaft  1602  may alternatively be driven in z-axis translation through operation of only one of the actuation systems  2708   a,b,  without departing from the scope of the disclosure. 
     Referring now to the enlarged inset graphics provided in  FIG. 27 , in some embodiments, gear teeth  2718  may be provided or defined on the inner surface of one or both of the drive belts  2702   a,b.  The gear teeth  2718  may be engageable with corresponding gear teeth  2720  defined on the shaft  1602 , or alternatively on the rack  1804 . In such embodiments, as the drive gears  2714   a,b  rotate, the respective drive belts  2702   a,b  are continuously fed through the idler rollers  2716   a,b  and along the length of the shaft  1602 , which enables intermeshing of the opposing gear teeth  2718 ,  2720 . Accordingly, driving the drive belts  2702   a,b  will allow the engaged opposing gear teeth  2718 ,  2720  to drive and move the shaft  1602  relative to the handle  1614  in z-axis translation. 
       FIG. 28  is a schematic side view of an example of the first actuation system  2708   a  of  FIG. 27 , according to one or more embodiments. While focused on the first actuation system  2708   a,  the following discussion is equally applicable to the second actuation system  2708   b  ( FIG. 27 ). As illustrated, the first actuation system  2708   a  includes the first drive shaft  2710   a  extending from the first drive input  2712   a  such that rotation of the first drive input  2712   a  correspondingly rotates the first drive shaft  2710   a.  Rotating the first drive input  2712   a  may operate or actuate a drive mechanism  2802  that may include any of a variety of interconnected gears, belts, chains, sprockets, etc. configured to ultimately drive the rack  1804 . In the illustrated embodiment, the drive mechanism  2802  comprises a type of gear train that includes one or more interconnected (or intermeshed) gears extending between the first drive shaft  2710   a  and the first drive gear  2714   a.  Accordingly, rotation (actuation) of the first drive shaft  2710   a  may correspondingly drive the first drive gear  2714   a  via the drive mechanism  2802  and thereby drive the first drive belt  2702   a,  which interacts with (e.g., extends around) the first drive gear  2714   a.    
     In the illustrated embodiment, the drive mechanism  2802  includes a beveled drive gear  2804  and a beveled driven gear  2806 . The beveled drive gear  2804  intermeshes with and is otherwise arranged to drive the beveled driven gear  2806 . The beveled drive gear  2804  is coupled to or forms part of the first drive shaft  2710   a  such that rotating the first drive shaft  2710   a  correspondingly rotates the beveled driven gear  2806 . Moreover, the first drive gear  2714   a  may be coupled to the beveled driven gear  2806  such that rotating the beveled driven gear  2806  correspondingly rotates the first drive gear  2714   a.  Accordingly, actuation of the first actuation system  2708   a  causes the first drive gear  2714   a  to engage and drive the first drive belt  2702   a  and thereby move the shaft  1602  ( FIG. 27 ) relative to the handle  1614  ( FIG. 27 ) in z-axis translation. 
     While the drive mechanism  2802  depicted in  FIG. 28  includes two geared components, those skilled in the art will readily appreciate that the drive mechanism  2802  may alternatively include more or less than two geared components to drive the first drive gear  2714   a.  Indeed, the depicted drive mechanism  2802  is but one example of a geared system or arrangement designed to drive the first drive gear  2714   a,  and various other designs or configurations of the drive mechanism  2802  may alternatively be incorporated into the first actuation system  2708   a  (e.g., mating helical gears), without departing from the scope of the disclosure. 
     As illustrated, in some embodiments, the first drive gear  2714   a  may define a depression or trough  2808  sized to receive the first drive belt  2702   a.  In some embodiments, the trough  2808  may interpose opposing sidewalls  2810  provided by the first drive gear  2714   a  and the sidewalls  2810  may be laterally offset a sufficient distance to accommodate the width of the first drive belt  2702   a.  Moreover, the sidewalls  2810  help prevent the first drive belt  2702   a  from escaping the trough  2808  as the first drive gear  2714   a  rotates and drives the first drive belt  2702   a.    
     In at least one embodiment, as illustrated, the first drive gear  2714   a  may have gear teeth  2812  defined thereon within the trough  2808 . In such embodiments, the gear teeth  2812  may be configured to intermesh with and engage the gear teeth  2718  ( FIG. 27 ) that may be provided by the first drive belt  2702   a.  Accordingly, rotating the first drive gear  2714   a  may drive the first drive belt  2702   a  via the intermeshed and engaged gear teeth  2718 ,  2812 . 
       FIG. 29  is a cross-sectional end view of a portion of the shaft  1602  and the first drive belt  2702   a,  according to one or more embodiments. While related to first drive belt  2702   a,  the following discussion is equally applicable to the second drive belt  2702   b  ( FIG. 27 ). In the illustrated embodiment, the shaft  1602  defines the channel  1806  and the first drive belt  2702   a  may be received within the channel  1806  to substantially seal the shaft  1602 , as generally discussed above. In such embodiments, the first idler roller  2716   a  may be arranged to help urge and press the first drive belt  2702   a  into the channel  1806  for a proper seal. 
     The first drive belt  2702   a  may be similar in some respects to the rack seal  2604  of  FIG. 26 . For example, the first drive belt  2702   a  may provide a top surface  2902  configured to generally align with the outer surface of the shaft  1602  when properly received in the channel  1806 . Moreover, in some embodiments, the top surface  2902  may be curved, arcuate, or otherwise shaped to match the curvature of the outer surface of the shaft  1602  such that the top surface  2902  may form a flush-fit engagement with the outer surface of the shaft  1602  when the first drive belt  2702   a  is properly received in the channel  1806 . In some embodiments, the first idler roller  2716   a  may define an arcuate or concave inner surface  2904  that receives the arcuate or convex outer surface  2902  of the first drive belt  2702   a.  The inner surface  2904  of the first idler roller  2716   a  may help deform and urge the first drive belt  2702   a  into the channel  1806 , which may help enhance the sealing capability of the first drive belt  2702   a  at the channel  1806 . Moreover, the inner surface  2904  of the first idler roller  2716   a  may help shape the first drive belt  2702   a  to properly fit within the channel  1806  to create a seal. 
       FIG. 30  is a cross-sectional end view of another portion of the shaft  1602  and the first drive belt  2702   a,  according to one or more additional embodiments. Again, while related to first drive belt  2702   a,  the following discussion is equally applicable to the second drive belt  2702   b  ( FIG. 27 ). In the illustrated embodiment, the shaft  1602  defines the channel  1806  and the first drive belt  2702   a  may be received within the channel  1806  to substantially seal the shaft  1602 . 
     In some embodiments, engagement between the channel  1806  and the first drive belt  2702   a  may comprise an interlocking engagement  3002  that helps secure the first drive belt  2702   a  within the channel  1806  and otherwise prevent inadvertent escape. More specifically, in at least one embodiment, the interlocking engagement  3002  may comprise a dovetail interlocking relationship where the first drive belt  2702   a  may be received within the channel  1806  in a dovetail-shaped interlock. The dovetail interlock between the first drive belt  2702   a  and the channel  1806  may prove advantageous in enhancing the sealing interface between the two components, but may also help secure the drive belt  2702   a  within the channel  1806  for operation. Those skilled in the art, however, will readily appreciate that other interlocking designs and configurations may be employed between the first drive belt  2702   a  and the channel  1806  to help enhance the seal interface between the two components, without departing from the scope of the disclosure. Moreover, in such embodiments, the first idler roller  2716   a  may be shaped or otherwise configured to force the first drive belt  2702   a  into the interlocking engagement  3002  and thereby enhance shaft sealing for insufflation and fluid ingress. 
       FIG. 31  is an enlarged schematic side view of another embodiment of the handle  1614  of  FIGS. 16-17 , according to one or more additional embodiments of the present disclosure. The outer body of the handle  1614  is again shown in phantom (dashed lines) to enable viewing of the internal space and components within the handle  1614 . Moreover, various actuation systems and component parts of the handle  1614  are omitted in  FIG. 31  for simplicity. The embodiment of the handle  1614  depicted in  FIG. 31  may be similar in some respects to the embodiment of the handle  1614  depicted in  FIG. 27 , and therefore may be best understood with reference thereto, where like numerals will correspond to like components not described again in detail. 
     The shaft  1602  extends through the handle  1614  and may be configured to move relative to the handle  1614  in z-axis translation. In the present embodiment, moving the shaft  1602  relative to the handle  1614  may be accomplished using a drive belt  3102  that extends along all or a portion of the shaft  1602 . In the illustrated embodiment, the drive belt  3102  may have a first or “proximal” end  3104   a  anchored to the shaft  1602  above (proximal to) the handle  1614  and at a distance sufficient to allow the shaft  1602  to translate relative to the handle  1614  (e.g., at or near the proximal end  2706  of the shaft  1602 ). A second or “distal” end  3104   b  of the drive belt  3102  may be anchored to the shaft  1602  below (distal to) the handle  1614  and at a distance sufficient to allow the shaft  1602  to translate relative to the handle  1614 . 
     The first actuation system  2708   a  described above in  FIG. 27  may be incorporated and otherwise operable (actuatable) to cause the shaft  1602  to move relative to the handle  1614  and thereby longitudinally advance or retract the end effector  1604  ( FIG. 16 ) in z-axis translation. As described above, the first actuation system  2708   a  includes the first drive shaft  2710   a  coupled to or forming part of a first drive input  2712   a,  and the first drive gear  2714   a  configured to drive the drive belt  3102 . More specifically, the drive belt  3102  interacts with (e.g., extends around) the first drive gear  2714   a  such that rotating the first drive input  2712   a  causes the first drive gear  2714   a  to rotate and thereby drives the drive belt  3102 . The actuation system  2708   a  also includes the idler rollers  2716   a,b  sized to receive and redirect the drive belt  3102  from the shaft  1602 , to the drive gear  2714   a,  and back to the shaft  1602 . 
     In the illustrated embodiment, the drive belt  3102  may include gear teeth  3106  provided or defined on the inner surface of the drive belt  3102 . The gear teeth  3106  may be engageable with corresponding gear teeth  3108  defined on the first drive gear  2714   a.  In such embodiments, as the drive gear  2714   a  rotates, the drive belt  3102  will be driven via intermeshed engagement between the opposing gear teeth  3106 ,  3108 . Moreover, since the drive belt  3102  is anchored to the shaft  1602  at proximal and distal ends  3104   a,b,  movement of the drive belt  3102  through rotation of the drive gear  2714   a  will cause the shaft  1602  to move relative to the handle  1614  in z-axis translation. 
     In other embodiments, however, the gear teeth  3106  may be engageable with corresponding gear teeth (not shown) defined on the outer surface of the shaft  1602 , or alternatively on the rack  1804  ( FIG. 26 ). In such embodiments, as the first drive gear  2714   a  rotates, the drive belt  3102  will be continuously fed through the idler rollers  2716   a,b  and along the length of the shaft  1602 , which enables intermeshing of the opposing gear teeth  3106  on the drive belt  3102  and the exterior of the shaft  1602  or on the rack  1804 , which may help drive and move the shaft  1602  relative to the handle  1614  in z-axis translation. Moreover, in embodiments where the drive belt  3102  is received within the channel  1806  ( FIG. 26 ) to engage the rack  1804 , the drive belt  3102  may be made of a compliant material capable of forming a sealed interface such as, but not limited to, an elastomer (e.g., rubber), a plastic, or a composite material. 
       FIGS. 32A and 32B  are isometric side and top views, respectively, of an example seal system  3200  that may be incorporated into one or more of the presently disclosed embodiments. In particular, the seal system  3200  may be incorporated into an embodiment that includes the shaft  1602 , which may include the outer shaft portion  1802  and the rack  1804  at least partially received within the longitudinal channel  1806  defined in the outer shaft portion  1802 . As illustrated, the rack  1804  may define gear teeth  3202  along at least a portion of its length, and the gear teeth  3202  may be engaged by opposing gear teeth of a drive gear (not shown) or a drive belt (not shown) to drive the rack  1804  and thereby cause the shaft  1602  to move relative to the handle  1614  in z-axis translation, or alternatively the rack  1804  may be driven independent of the shaft  1602  and translated within the channel  1806  to cause a knife to advance or retract (e.g., “fire”). 
     The seal system  3200  may be included in the handle  1614  of any of the embodiments described herein that include the rack  1804 . As the shaft  1602  moves in z-axis translation or as the rack  1804  moves relative to the shaft  1602 , the seal system  3200  remains stationary with the handle  1614  and provides a sealed interface between the handle  1614  and the shaft  1602 . 
     As illustrated, the seal system  3200  may include a roller seal  3204  and a stationary flange seal  3206 . The roller seal  3204  may be arranged to engage the rack  1804 . More particularly, the roller seal  3204 , alternately referred to as a “rotating labyrinth seal,” may be freely rotatable and include gear teeth  3208  configured to intermesh with the gear teeth  3203  of the rack  1804 . Consequently, as the shaft  1602  or the rack  1804  translate during operation, the roller seal  3204  will roll in contact along the rack  1804  as the opposing gear teeth  3202 ,  3208  interact with each other. The roller seal  3204  may provide a sealed interface against the rack  1804  that helps seal the exposed channel  1806 . In some embodiments, for example, the roller seal  3204  may be made of a compliant material, such as a soft elastomer or a foam that is able to roll in contact with the mating teeth  3202  of the rack  1804 , while simultaneously providing a sealed interface. 
     The flange seal  3206  extends partially around the outer circumference of the shaft  1602  and extends radially outward therefrom to provide a sealed interface at the outer surface of the shaft  1602 . The flange seal  3206  may also extend to and slidingly engage the opposing lateral sides of the roller seal  3204 . In some embodiments, the flange seal  3206  may comprise an elastomeric skirt seal, but could alternatively comprise any other type of seal capable of sealing about the outer circumference of the shaft  1602  and slidingly engaging the lateral sides of the roller seal  3204 . As the shaft  1602  translates during operation, the flange seal  3206  may dynamically seal against the outer surface of the shaft  1602 , and may also dynamically seal against the lateral sides of the roller seal  3204  as the roller seal  3204  rolls in contact along the moving rack  1804 . 
     Pneumatic Seal Cartridge for Robotic Vessel Sealer 
       FIG. 33  is a partial cross-sectional side view of an example handle  3300 , according to one or more embodiments. The handle  3300  may be similar in some respects to the handle  1614  described herein, and may thus be incorporated into the surgical tool  1600  of  FIGS. 16-17 . As illustrated, an elongate shaft  3302  may extend through the handle  3300  and may be configured for z-axis translation relative to the handle  3300 . To accomplish this, the handle  3300  may further include an actuation system  3304  that includes a spool  3306  and one or more drive cables  3308  (two shown) at least partially wrapped around the spool  3306  and extending longitudinally along a portion of the shaft  3302 . The actuation system  3304  further includes upper and lower idler pulleys  3310   a  and  3310   b  rotatably coupled to the handle  3300  and arranged to redirect the drive cables  3308  between the shaft  3302  and the spool  3306 . 
     In the illustrated embodiment, the drive cables  3308  are received and extend within a groove  3312  defined along all or a portion of the length of the shaft  3302 . The groove  3312  may be accompanied by various other longitudinal passages or grooves  3314  defined longitudinally along the shaft  3302  to accommodate other types of cables or drive members. The grooves  3312 ,  3314  result in the shaft  3302  exhibiting a non-circular cross section created by the longitudinal passages that could allow insufflation air to leak from a patient. To prevent insufflation air leakage, the handle  3300  may further include one or more seal cartridges  3314  (one shown) configured to seal about the non-circular cross section of the shaft  3302 . 
     In the illustrated embodiment, the seal cartridge  3314  is arranged about the shaft  3302  at or near the distal (bottom) end of the handle  3300 . While not shown, a second seal cartridge (not shown) may be arranged about the shaft  3302  at or near the proximal (top) end of the handle  3300 . As illustrated, the drive cable  3308  extends through the seal cartridge  3314 , which is configured to seal about the drive cable  3308 . 
       FIGS. 34A and 34B  are isometric and top views, respectively, of an example of the seal cartridge  3314  of  FIG. 33 , according to one or more embodiments. As illustrated, the seal cartridge  3314  may include a housing  3402  having a seal membrane  3404  arranged within the housing  3402 . The housing  3402  may be made of a rigid or semi-rigid material such as, but not limited to, a metal (e.g., stainless steel, aluminum, titanium, etc.), a polymer, a composite material, or any combination thereof. In the illustrated embodiment, the cross-sectional shape of the housing  3402  is circular, but could alternatively comprise other shapes, such as oval, ovoid, polygonal (e.g. triangular, rectangular, etc.), without departing from the scope of the disclosure. 
     The seal membrane  3404  has a generally circular outer circumference (perimeter) generally matable with the inner surface of the housing  3402 . As best seen in  FIG. 34A , in some embodiments, the seal membrane  3404  may comprise one or more flexible seals  3406  vertically stacked with one or more structure plates  3408 . The flexible seals  3406  may be made of any compliant sealing material including, but not limited to, an elastomer (rubber), a polymer, or a composite material. In at least one embodiments, the flexible seals  3406  may contain at least one fiber or filler for the purpose of mechanical reinforcement, lubricity, or to act as a wear modifier. Moreover, the seals  3406  may be impregnated with synthetic oils or organic compounds to increase lubricity and reduce static or kinetic friction. As will be appreciated, decreasing friction helps with robotic controls and accuracy. In contrast, the structure plates  3408  may be made of a rigid or semi-rigid material, such as a metal, a plastic, or a composite material. In some embodiments, the various layers of the seals  3406  may comprise materials of varying (different) durometers. Similarly, the various layers of the structure plates  3408  may comprise materials of varying (different) durometers. 
     The seals  3406  and the structure plates  3408  may be die cut and stacked in assembling the seal membrane  3404 . In at least one embodiment, once the seals  3406  and the structure plates  3408  are stacked, the housing  3402  may be overmolded onto the assembled seal membrane  3404 . In the illustrated embodiment, two flexible seals  3406  are alternatingly stacked with two structure plates  3408 , but more or less than two of each may be provided, without departing from the scope of the disclosure. 
     As best seen in  FIG. 34B , the seal membrane  3404  defines an arcuate shaft surface  3410  and one or more nubs or projections  3412  extending radially inward from the shaft surface  3410 . The projections  3412  may be configured to be received within corresponding passages or grooves defined longitudinally in a tool shaft, such as the grooves  3312 ,  3314  ( FIG. 33 ) of the shaft  1602  ( FIG. 33 ), thus helping to reduce the risk of air leakage from a patient during surgery. As illustrated, each projection  3412  may also define an aperture  3414  configured to receive a longitudinally-extending drive member of the surgical tool, such as the drive cables  3308  ( FIG. 33 ). As the shaft  1602  translates relative to the handle  3300  ( FIG. 33 ), the projections  3412  may be configured to translate (slide) within the grooves  3312 ,  3314  while receiving corresponding drive members, thereby creating a sliding linear seal for instrument shaft motion. The seal membrane  3404  directly contacts at least one surface of the tool shaft and at least one cable, tube, or drive rod passing through or parallel to the tool shaft axis for the purpose of creating a pneumatic seal. Any cable, tube, or drive rod contacting at least one surface of the seal membrane  3404 , and passing through the handle  3300  ( FIG. 33 ) to a distal end effector, does so for the purpose of actuating the end effector. 
     One skilled in the art will appreciate that while the seal cartridge  3314  is shown with a plurality of projections  3412  that are rounded and spaced substantially symmetrically around an inner perimeter, the inner portion of the seal cartridge  3314  can assume other shapes as well, so long as the molding process substantially matches the interior of the seal cartridge  3314  to the outer surface of the instrument shaft  3302 . 
     As best seen in  FIG. 34A , the seal cartridge  3314  may contain at least one outer seal  3316  configured to form a sealed interface between the housing  3402  and an inner surface of the handle  3300  ( FIG. 33 ), such as in the nose cone of the instrument. The outer seal  3316  may comprise, for example, an elastomeric O-ring, flange, or other commonly available sealing member. At least one surface of the handle  3300  may contact the outer seal  3316  for the purpose of forming a pneumatic seal. 
     3. Implementing Systems and Terminology. 
     Implementations disclosed herein provide systems, methods and apparatus for instruments for use with robotic systems. It should be noted that the terms “couple,” “coupling,” “coupled” or other variations of the word couple as used herein may indicate either an indirect connection or a direct connection. For example, if a first component is “coupled” to a second component, the first component may be either indirectly connected to the second component via another component or directly connected to the second component. 
     The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is required for proper operation of the method that is being described, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. 
     As used herein, the term “plurality” denotes two or more. For example, a plurality of components indicates two or more components. The term “determining” encompasses a wide variety of actions and, therefore, “determining” can include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” can include resolving, selecting, choosing, establishing and the like. 
     The phrase “based on” does not mean “based only on,” unless expressly specified otherwise. In other words, the phrase “based on” describes both “based only on” and “based at least on.” 
     As used herein, the terms “generally” and “substantially” are intended to encompass structural or numeral modification which do not significantly affect the purpose of the element or number modified by such term. 
     To aid the Patent Office and any readers of this application and any resulting patent in interpreting the claims appended herein, applicants do not intend any of the appended claims or claim elements to invoke 35 U.S.C. 112(f) unless the words “means for” or “step for” are explicitly used in the particular claim. 
     The foregoing previous description of the disclosed implementations is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these implementations will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the scope of the invention. For example, it will be appreciated that one of ordinary skill in the art will be able to employ a number corresponding alternative and equivalent structural details, such as equivalent ways of fastening, mounting, coupling, or engaging tool components, equivalent mechanisms for producing particular actuation motions, and equivalent mechanisms for delivering electrical energy. Thus, the present invention is not intended to be limited to the implementations shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.