Patent Publication Number: US-2021169598-A1

Title: Articulating surgical instrument

Description:
This application is a continuation of U.S. application Ser. No. 16/999,943, filed Aug. 21, 2020, which is a continuation in part of U.S. application Ser. No. 16/732,306, filed Dec. 31, 2019, which claims the benefit of U.S. Provisional Application No. 62/787,244, filed 31 Dec. 2018, and U.S. Provisional Application No. 62/787,303, filed 1 Jan. 2019. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to the field of surgical devices and systems, including those using electromechanical actuation. 
     BACKGROUND 
     There are various types of surgical robotic systems on the market or under development. Some surgical robotic systems use a plurality of robotic arms. Each arm carries a surgical instrument, or the camera used to capture images from within the body for display on a monitor. See U.S. Pat. No. 9,358,682 and US 20160058513, which are incorporated herein by reference. Other surgical robotic systems use a single arm that carries a plurality of instruments and a camera that extend into the body via a single incision. Each of these types of robotic systems uses motors to position and/or orient the camera and instruments and to, where applicable, actuate the instruments. Typical configurations allow two or three instruments and the camera to be supported and manipulated by the system. Input to the system is generated based on input from a surgeon positioned at a master console, typically using input devices such as input handles and a foot pedal. Motion and actuation of the surgical instruments and the camera is controlled based on the user input. The image captured by the camera is shown on a display at the surgeon console. The console may be located patient-side, within the sterile field, or outside of the sterile field. 
       FIG. 1A  shows components of a robotic surgical system  10  of the type described in U.S. Pat. No. 9,358,682 and US 20160058513. Features of the system  10  are shown to facilitate an understanding of the way in which the concepts of the present invention may be implemented, but it should be understood that the invention may be used with a variety of different surgical or industrial robotic systems and is not limited to use with system  10 . 
     System  10  comprises at least one robot arm  11  which operates under the control of a command console  12  operated by the surgeon, as described in the Background. The robotic manipulator (or each robotic manipulator) has a terminal portion  13  designed to support and operate a surgical device assembly  14 . The surgical device assembly includes a surgical instrument having shaft  15  and a distal end effector  17  positionable within a patient  16 . 
     In this configuration, the manipulator arm receives the surgical device assembly  14  at the terminal portion  13  as shown in  FIG. 2 . The surgical device assembly includes a proximal housing  20  that is received by the terminal portion  13  as shown. 
     The end effector  17  may be one of many different types of that are used in surgery including, without limitation, end effectors  17  having one or more of the following features: jaws that open and close, section at the distal end of the shaft that bends or articulates in one or more degrees of freedom, a tip that rolls axially relative to the shaft  15 , a shaft that rolls axially relative to the manipulator arm  11 . For the sake of simplicity, in  FIG. 1B  the end effector  17  is shown as an oval form in broken lines. The system includes instrument actuators for driving the motion of the end effector  17 . These actuators, which might be motors or other types of actuators (e.g. hydraulic/pneumatic), are positioned in the terminal portion  13  of the robotic manipulator, or in the housing  20  of the surgical device assembly, or some combination of the two. In the latter example, some motion of the end effector might be driven using one or more motors in the terminal portion  13 , while other motion might be driven using motors in the housing  20 . 
     During use, the robotic system controls movement of the robotic manipulator and movement of the end effector (e.g. jaw open/close, tip roll, articulating or bending, etc.) based on surgeon input received by the system via the console  12 . The control signals used to generate the various types of movement depend in some cases on the geometry, length, weight, or other parameters of the surgical instrument  14 . 
     The system is configured to allow removal and replacement of surgical instruments  14  during the course of a procedure, so that instruments with different end effector types may be chosen as the surgeon&#39;s needs require. 
     Instruments that can articulate in multiple degrees of freedom can be particularly useful to a surgeon because their dexterity can simplify relatively complex tasks. Some commercially available instruments used in robotic surgery make use of three wire loops (or  6  wires) for control of the instruments degrees of freedom. A first of the loops is dedicated to one degree of freedom—the yaw motion of the instrument. A second loop controls the pitch of one jaw and the third controls the pitch of the second jaw. In the case of bipolar instruments, these instruments also run two additional cables down the instrument shaft. This brings the total number of wires/cables running the length of the shaft to 8 wires. 
     The described instruments are designed to minimize the overall size of the instrument shaft, as well as reducing the complexity of the assembly and part count. The instrument uses two cable loops to control pitch, yaw and jaw actuation. Some embodiments are configured to enable electrical energy to be passed through the mechanical control cables to deliver monopolar and bipolar energy to the instrument jaws. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  schematically illustrates a robotic manipulator of a type used in robotic surgical procedures. 
         FIG. 1B  illustrates the step of mounting of a surgical device onto the manipulator of  FIG. 1A . 
         FIG. 2  is a perspective view of an instrument showing the shaft and distal end. 
         FIG. 3  is a perspective view of the distal end of the instrument. 
         FIG. 4  is an exploded perspective view of the jaw members and second link of the instrument. 
         FIG. 5  is a perspective view of the second link and associated cable guide. 
         FIG. 6  is a similar to  FIG. 3 , but the second link and a portion of the cable guide have been removed. 
         FIG. 7  is a perspective view of one jaw member and its corresponding cables. 
         FIG. 8  is an exploded perspective view of the first link and its contents. 
         FIG. 9  is a perspective view of the proximal end of the instrument shaft, showing the drive cables and stiffening cable. 
         FIG. 10  is a perspective view of a second embodiment of an instrument. 
         FIG. 11  is an exploded perspective view of a jaw member assembly of the instrument of  FIG. 10 . 
         FIG. 12A  shows the jaw member of the assembly of  FIG. 11  assembled with the medial pulley section. The most proximal features of the jaw member are shown as shaded to allow easy differentiation between them and the surrounding medial pulley section. 
         FIG. 12B  shows a portion of a slightly modified version of the jaw member of  FIG. 12A , in which the pass-through has a piercing feature. 
         FIG. 13  is a perspective view showing the inner surface of the lateral pulley section of the assembly  FIG. 11 . 
         FIG. 14  shows an insulated electrical cable with conductive hypotube swaged on an electrically exposed region. 
         FIG. 15  shows the medial pulley of the assembly of  FIG. 11  with a cable positioned on it. 
         FIG. 16  shows the jaw member assembly of  FIG. 11  assembled with a cable. 
         FIG. 17  is similar to  FIG. 10 , but shows the clevis cover removed from the first link. 
         FIG. 18  is a perspective view of the second link. 
         FIG. 19  shows the distal link assembled with the distal pulleys. The proximal pulleys and their corresponding pins are also shown. 
         FIG. 20  is similar to  FIG. 19  but also shows the cables. For clarity, one cable is lightly shaded and the other cable is more darkly shaded. 
         FIG. 21  shows the first link assembled to the second link. 
         FIG. 22  is a plan view of the boss and the pins for the proximal pulleys. 
         FIG. 23  is a perspective view of the proximal end of the instrument shaft. 
         FIG. 24A  shows an alternative second link configuration in accordance with a third embodiment. 
         FIG. 24B  is an exploded view of the link configuration of  FIG. 24A . 
         FIG. 25  is similar to  FIG. 24A , but also shows the pulleys. 
         FIG. 26  shows a side view of jaw members, distal pulleys, and a tendon and illustrates a fleet angle of the tendon. 
     
    
    
     DETAILED DESCRIPTION 
     First Embodiment 
     Details of a first embodiment of an instrument  200  will next be described with reference to  FIGS. 2 through 9 . 
     Referring to  FIGS. 2 and 3 , the distal end of the instrument  200  includes a first link  210  mounted on the distal end of the shaft  202 . A second link  212  is coupled by a pin  224  to the first link  210 , allowing the second link to pivot relative to the first link. Each of the links  210 ,  212  is preferably a clevis type of link. A pair of jaw members  214 ,  215  are coupled to the second link  212  by a pin  216  (e.g. at a distally extending member of clevis link  212  as is shown) such that the jaw members  214 ,  215  can independently pivot about the pin  216  relative to the second link  212 . 
     Four drive cables extend through the shaft  202  and links  210 ,  212  to the end effector: first cables  314   a ,  314   b , which terminate at jaw member  214 , and second cables  315   a ,  315   b  that terminate at jaw member  215 . In this description, cables  314   a ,  315   a  may be referred to as “upper cables” and cables  314   b ,  315   b  may be referred to as “lower cables”. All orientation references such as these are used for the sake of convenience in describing the orientation of these features in the drawings, and should not be construed to require a particular orientation for the end effector etc. 
     Each jaw member may include cable guide features around which the cables are routed. In the jaw members shown in the drawings of the first embodiment, the proximal portion of the jaw member is shaped similar to a pulley, with a partially-annular groove  218  having a profile that curves with a constant radius relative to the axis of the pin  216 . The groove  218  for jaw member  214  is shown in  FIG. 7 . As shown, the upper cable  314   a  and the lower cable  314   b  pass along the groove in opposite directions, meeting at a common anchor point. In this embodiment, the distal end of each cable  314   a ,  314   b  is secured to a common ball crimp  220  that is secured within a recess in the jaw member  214 . It should be mentioned that in this and the subsequent embodiments, each of the cables  314   a ,  314   b  may be a single cable, with crimp  220  only used to secure the cable to the jaw member (and, in some embodiments, to provide electrical conduction to the jaws, as discussed below), or it may be two cables crimped together by crimp  220 . 
     Referring again to  FIGS. 4-5 , additional cable guides  222  for the upper and lower cables are housed within the second link  212 . In  FIG. 6 , the second link  212  is not shown and only the lower cable guides  222  are shown, so as to allow the path of the lower cables  314   b ,  315   b  through the cable guide  222  to be seen. 
     From the cable guides  222 , the cables extend proximally into the first link  210 , which may be a clevis-type link as shown.  FIG. 8  gives a partially exploded view of the first link  210  so its contents can be seen. Within the first link  210  is a pair of parallel pins  224 ,  226 . Each of these pins has four cable pulleys  228   a - d  rotatably positioned on it as shown. Each of the cables  314   a ,  314   b ,  315   a ,  315   b  extends in a first direction around one of the pulleys and then in the opposite direction around the co-axially adjacent pulley. In the drawings, upper cable  314   a  extends around pulleys  228   a , upper cable  315   a  extends around pulleys  228   b . The lower cables  314   b ,  315   a  extend around lower pulleys  228   c  and  228   d , respectively. As best shown in  FIG. 3 , proximally-extending tongue  230  of second link  212  is positioned on the pin  224 , between pulleys  228   a  and  228   c , to allow the second link  212  to pivot about the pin  224  relative to the first link  210 . A washer  232  is disposed between pulleys  228   a  and  228   c  on the second pin  226 , allowing the pulleys on the pins  224  to remain aligned with their counterparts on pin  226 . 
     Referring again to  FIG. 8 , the cables pass proximally from the first link  210  into the instrument shaft  202 . To maintain orientation and alignment of the cables, they may pass over or through an additional cable guide as they enter into the instrument shaft  202 . One such cable guide  234  is shown in  FIG. 8 . 
     The proximal ends of the drive cables  314   a - b ,  315   a - b  are engaged with actuators that may be disposed in a housing at the proximal end of the shaft  202 . These actuators are driven by or receive mechanical input from drive motors disposed within a component of the robotic surgical system that receives the instrument, such as the terminal portion of the robotic arm. One configuration is shown in commonly owned co-pending application Ser. No. 16/732,307, entitled Compact Actuation Configuration and Expandable Instrument Receiver for Robotically Controlled Surgical Instruments, filed Dec. 31, 2019, which is incorporated herein by reference. The actuators may be configured to receive linear and/or rotational drive input to selectively alter the tension on the drive cables, resulting in movement of the jaws and/or link  212 . 
     Given the arrangement of cables at the end effector, movement in accordance with the following degrees of freedom can be achieved using combination of tension in the respective cables listed on Table 1 below. Note that in the table, “+” means tension is applied to, or increased in, the cable, and “−” means tension is reduced or released. The indications of “up”, “down” are relative to the page of the figures. The indications of “left” and “right” are assuming the user is looking distally down the shaft of the instrument towards the end effector. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Cables for 
                 Cables for 
                   
               
               
                   
                 Jaw Member 214 
                 Jaw Member 214 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Cable 
                 Cable 
                 Cable 
                 Cable 
                   
               
               
                   
                 314a 
                 314b 
                 315a 
                 315b 
                 Pivot 
               
               
                 Movement 
                 (upper) 
                 (lower) 
                 (upper) 
                 (lower) 
                 Axis 
               
               
                   
               
               
                 Pitch Up 
                 + 
                 − 
                 + 
                 − 
                 Pin 216 
               
               
                 Pitch Down 
                 − 
                 + 
                 − 
                 + 
                 Pin 216 
               
               
                 Yaw Left 
                 − 
                 − 
                 + 
                 + 
                 Pin 224 
               
               
                 Yaw Right 
                 + 
                 + 
                 − 
                 − 
                 Pin 224 
               
               
                 Jaw Open 
                 + 
                 − 
                 − 
                 + 
                 Pin 216 
               
               
                 Jaw Close 
                 − 
                 + 
                 + 
                 − 
                 Pin 216 
               
               
                   
               
            
           
         
       
     
     An additional degree of freedom of the end effector is that of that axial rolling, which is achieved by rotating the shaft  202  about its axis. 
     As indicated in Table 1, yaw motion of the end effector in one direction or the other involves simultaneously tensioning both cables associated with one jaw member and simultaneously relaxing both cables associated with the other jaw member. Pitch motion is achieved by pivoting both jaws in the same direction (up or down) about pin  216 . As shown in Table 1, upward pitch results when both upper cables  314   a ,  315   a  are tensioned while both lower cables  314   b ,  315   b  are relaxed, and downward pitch occurs when the lower cables are tensioned and the upper cables are relaxed. The jaws are closed, such as for grasping, by pivoting jaw members  214 ,  215  towards one another about pin  216 . As shown on Table 1, to close the jaws, lower cable  314   b  of jaw member  214  and upper cable  315   a  of jaw member  215  are tensioned. To open the jaws, upper cable  314   a  of jaw member  214  and lower cable  315   b  of jaw member  215  are tensioned. 
     The cables may be stainless steel braided cables, tungsten braided cables, or any other tendon, wire or cable having the appropriate strength, durability and other properties for its intended use. Note that in this description the terms “tendon,” “wire,” and “cable” are used broadly to encompass any type of tendon that can be used for the described purpose. 
     The shaft  202  may be rigid, as may be suitable for use with the systems described in the Background, or it may include an elongate flexible section so that it may be used through flexible (e.g. steerable) cannulas.  FIG. 9  shows one example of a flexible shaft design, which includes an inner member  236  having multiple lumen for accommodating the drive cables. A coil pipe  238  is disposed over the inner member  236 , and an outer layer  239  former of braided Pebax or other suitable material covers the coil pipe  238 . Inner member  236  may include four lumen for the four drive cables  314   a - b ,  315   a - b , as shown, plus a central lumen housing an additional stiffening cable  240 . Cable  240  has a distal end terminating at the distal end of the shaft such that tensioning the cable compresses the windings of the coil pipe  238 , increasing its rigidity. Referring to  FIG. 8 , in the drawings the cable  240  is anchored by a ball crimp to the cable guide  234  positioned within the first link  210 . The system may be configured to apply tension to the cable in one of several ways, e.g. the tension may be continuously applied, or it might be dynamically applied by a motor during use of the system. 
     Second Embodiment 
       FIGS. 10-23  show a second embodiment of an instrument  400 , which is suitable for electrosurgical instruments in which electrical energy is conducted to one or both jaw members for delivery to body tissue, but which has features that may be used for non-electrosurgical instruments as well. It shares many common features with the first embodiment. Those that differ will be discussed here. Although a Maryland dissector end effector is shown, the instrument may be manufactured using any jaw configuration useful in surgery, including graspers, scissors, and needle holders, or other end effectors for which pitch and yaw motion is useful but there are no jaws to actuate. For example, the instrument may be manufactured with a single “jaw” that does not open and close, but is steerable in pitch and yaw. Examples of these configurations include monopolar hooks, monopolar spatulas, and suction/irrigation devices. 
     The end effector of the instrument  400  has a pair of jaw member assemblies  414 ,  415 . An exploded view of one of jaw member assemblies  415  of the second embodiment is shown in  FIG. 11 ; the other 414 has identical features except for differences between the jaw members themselves that may be dictated by the type of surgical instrument. Each jaw member assembly includes a jaw member  450 , medial pulley section  452 , and a lateral pulley section  454 . Jaw member  450  has a collar  456  connected to the jaw by a proximally-extending stem  458 . A pass-through  460  in the stem  458  receives the cable (not shown, but see  FIG. 15 ) for mechanical actuation of the jaw member  450  and, optionally, for conduction of electrical energy to the jaw member  450 . 
     When the jaw member assembly  415  is assembled, the collar  456  of the jaw member  450  is captured between the medial and lateral pulley sections  452 ,  454 . One of the pulley sections may include an annular post  462  to help retain the jaw member  450  between the pulley section. In this embodiment, the lumen of the collar  456  of the jaw member  450  is disposed over the annular post  462 . See  FIG. 12A . When the end effector is fully assembled, pin  416  (which is the pin about which the jaw members pivot for open-close and pitch motion) extends through the lumen of the posts  462  of each of the jaw member assemblies. See  FIGS. 12A and 16 . 
     The medial and lateral pulley sections have opposed faces possessing surface geometry that, when they are assembled, define an annular pathway through which the cable is routed. In the illustrated embodiment, an annular rib  464  on one of these pulley sections (shown on the medical section but it may be on either) may contact the opposed face of the other of the pulley sections to define the pathway. As will be understood from viewing  FIG. 12A , the cable pathway defined by annular rib  464  is aligned with the pass-through  460  (in the stem  458 ) from which the cable extends. In this drawing, the most proximal features of the jaw member  350  are shown as shaded so those features may be easily differentiated from those of the medial pulley section. The lateral pulley section is hidden in this view to allow these features to be seen, but its face that opposes the medial pulley section is shown in  FIG. 13 . The cable  415   a ,  415   b  routes around the annular rib  464  as shown in  FIGS. 15 and 16  and is captured within the jaw member assembly by the contact between the edges of the rib  464  and the opposed face of the lateral pulley section  454 . It should be understood that the geometry of the medial and lateral pulley sections&#39; opposed faces may have any configuration that forms an annular pathway for routing of the cable. Examples include various combinations of annular ribs and/or channels, and recesses and/or faces. 
     The three primary elements of the jaw member assembly may be keyed or mated together to ensure rotation as a unit during use. Referring to again to  FIGS. 12A and 13 , as one non-limiting example, a distal face of the medial pulley section  452  includes a lateral slot that receives the stem  458  of the jaw member  450  and a tab  466  of the lateral pulley section  454 . 
     Where the jaw assembly is used for electrosurgical applications, the jaw member  450  is formed of a conductive material, while the medial and lateral pulley sections are formed of insulating materials. 
     A particular advantage of the disclosed jaw assembly is that it allows a variety of articulating instrument types (e.g. Maryland grasper, needle holder, scissors) to be assembled from sets of components that are identical to one another except for the jaw member  450  itself. In other words, the component parts can be manufactured so that each instrument type can utilize identical medial and lateral pulley sections, but different jaw members  450  having the appropriate jaw shapes. 
     For electrosurgical instruments, the second embodiment provides the advantages of delivering both mechanical and electrical energy with the same cables, which reduces the number of cables needed for the instrument. This also allows the use of larger cables (for increased strength), or a reduction in the diameter of the instrument shaft than might be achieved using separate electrical and mechanical cables. 
     Methods and configurations for electrically and mechanically connecting the cables to the jaw members will next be described. The purpose of these concepts is to achieve a mechanical bond between jaw and cable capable of delivering adequate jaw grasping and spreading strength as well as to achieve an electrical bond between jaw and cable capable of reliably delivering electrocautery to the surgical site. These two requirements must be achieved in such a way that the rest of the instrument remains isolated from the electricity passing through the cable to the jaw to prevent undesired tissue damage. 
     According to a first method, each cable (see cable  415   s  in  FIGS. 14 and 15 ) used for mechanical and electrical energy delivery is a cable covered or coated with an insulative material, such as an extrusion-coated conductive cable. The coating on the cable is selectively stripped at a location where the jaw is to be crimped in place. For example, where a single wire loop is used through each jaw, insulation is locally removed from the approximate mid-point or the middle region of the cable to create an exposed region. The ends of the cables can also be stripped, and with a service loop long enough to compensate for cable travel, the ends can be attached to the external energy connectors. The removal process could be performed manually with a blade or wire stripping tool or through a more automated processes including, but not limited to, laser ablation, etching, localized melting, etc. 
     The cable is assembled with the relevant electrically conductive jaw member with the exposed conductive region positioned in electrical contact with the jaw member. When a jaw member of the type used for the  FIG. 12A  embodiment is used, the cable passes through pass-through  460  such that the exposed region of the cable is within the pass-through. This is the location at which the coated cable is engaged with the end effector jaw for both jaw movement and electrical conduction. The pass-through  460  is large enough for the coated cable to pass through, but small enough to engage with the uncoated section of cable when crimped in the assembly process. In a preferred embodiment illustrated in  FIG. 14 , a section of electrically conductive hypotube  417  is swaged to the cable  415   a  to fill the area of removed insulation with an electrically conductive material. The swaged hypotube  417  is then fed into the pass-through  460 . Once the jaw is crimped to the cable loop, it is electrically coupled with the cable, while the remaining length of the cable remains insulated. 
     In a slight modification to this embodiment, the hypotube  417  may be coupled to the jaw prior to crimping. For example it might be positioned in the pass-through such as by being welded or otherwise attached to the jaw or seated in a pocket positioned on the jaw. 
     In an alternative method, the cable is one coated with a dielectric polymer. The jaw is formed with a cable pass-through  460   a  having a geometry designed such that compression of the pass-through during crimping will pierce the dielectric polymer coating on the cable, creating the electrical connection between cable and jaw. At the same time, the compression of the pass-through creates the mechanical bond between cable and jaw. Referring to  FIG. 12B , the geometry of the pass-through  460   a  may, for example, include a sharp member  461  that extends into the pass-through, with “sharp” intended to mean that it is sufficiently sharp to penetrate the polymer coating during crimping. As one specific example, the member may extend radially inwardly and include a sharpened edge oriented parallel to the axis of the pass-through. In other examples, the sharp member will have different shapes and orientations. 
     A third method also uses a length of cable coated with a dielectric polymer. In this method, the section of the cable that is to be crimped to the jaw member is identified and the coating in that section is removed prior to crimping the jaw to the cable. Once the segment of coating has been removed, the cable may be inserted through the pass through in the jaw such that the jaw is aligned with the uncoated segment. Once aligned, the jaw is crimped and the compression of the pass through creates the electrical and mechanical connection to the cable beneath the dielectric coating. 
     A fourth method makes use of a length of cable that is not coated with a dielectric polymer. It is fed through pass-through  460  in the jaw member. The pass-through is compressed in a crimping operation to create the mechanical and electrical connection between cable and jaw. Dielectric material is applied over each portion of the cable extending away from the pass-through, providing electrical isolation along the length of the cable that is outside the pass-through. This dielectric material may be heat shrink tubing or some other tubing applied on the cable, or it might be a dipped or sprayed dielectric coating. If heat shrink tubing is used, the cable will be fed into the tube and the tube shrunk down onto the cable to form a physical barrier between the cable and the rest of the instrument assembly. 
     A fifth method makes use of two separate cables to form the cable coupled to a jaw. In this configuration, the end of each cable is stripped of the dielectric polymer coating. The stripped ends of both cables are positioned in the pass-through  460  in the jaw member and the pass-through is then compressed in a crimping operation. 
     Features unique to this invention include the use of a shaped pass through designed to pierce a dielectric coating on a wire during the fabrication of a surgical instrument, and the application of heat shrink tubing to either side of an uncoated cable, after that cable has been crimped to a surgical instrument jaw. 
     In each embodiment, because the cable is pulled through a series of pulleys and conductive structures for steering the instrument end effector, the insulative coating is sufficiently thick and durable to prevent electrical energy conducted through the cable from passing to components of the instrument that are not intended to be energized. 
     When both jaws have been crimped to the middle of each coated cable, the assembly of the joints of the instrument can begin. The coated cables are threaded through the pulley structure and down the instrument shaft to the cable control geometry. The exposed free ends of each cable loop are attached to an electrical connector to which a line from an electrosurgical generator unit may be coupled in the operating room. In preferred configurations, there is a service loop between the electrical connector and the actuation mechanism that is configured to engage with the robotic manipulator. The service loop allows the actuation mechanism to progress through its range of motion without imparting stress to the section of cable that is attached to the electrical connector. 
     Referring to  FIG. 17 , the first and second links  410 ,  412  of the second embodiment perform similar functions to the first and second links  210 ,  212  of the first embodiment. The pin  416  couples each of the lateral and medial pulley sections  452 ,  454  and each of the jaw member assemblies  414 ,  415  to the second link  412  at its distally-extending clevis. A transverse face  421  of the second link  412  includes wire guide openings  413  for the four cable segments  414   a,b  and  415   a,b . See also  FIG. 18 . A tongue  430  ( FIG. 18 ) extends proximally from the face  421 . Bosses  431  extend from opposite sides or faces of the tongue. As shown in  FIG. 19 , rather than rotating on a pin, the distal pulleys  428   a - d  rotate on these bosses  431 , with upper pulleys  428   a ,  428   b  on the upper boss  431 , and lower pulleys  428   c ,  428   d  on the lower boss (not visible in  FIG. 19 ). This helps to prevent the link  412  from binding the pulleys due to tilting or sliding along its pivot axis A, which can occur in response to load changes on the cables. A pin  424  extends through the bosses  431 . This pin is used to couple the second link  412  and distal pulleys  428   a - d  to the first link  410 , as shown in  FIG. 17 . 
     The wire guide openings  413  may be defined by a single integral component, or they may be defined by a combination of more than one component, depending on the desired material properties of the guiding surfaces. 
       FIG. 21  shows the first link  410  assembled with the second link  412 . A tab  432  extends between and in parallel to the link&#39;s longitudinally-extending clevis arms. A first pin  426   a  extends between the upper clevis arm and the tab  432 , and a second pin  426   b  extends between the tab  432  and the lower clevis arm. Proximal pulleys  429   a - d  rotate on these pins, with two pulleys  429   a - b  on one side of the tab  432  and two pulleys  429   c - d  on the other side of the tab. Separating these pulleys allows the pulleys on the bosses  431  to remain aligned with their counterparts on pins  426 . Referring to the plan view of the bosses  431  and pins  426   a,b  shown in  FIG. 22 , pins  426   a,b  preferably do not share a common axis. In the illustrated embodiment, the axes are laterally offset from one another and from the longitudinal axis LA of the instrument. On the other hand, the bosses  431  have axes that intersect the longitudinal axis LA of the instrument. In alternative embodiments, the pins  426   a,b  may be axially aligned, or they might even comprise a single pin extending from the upper clevis arm, through an opening in the tab  432 , to the lower clevis arm. 
     Arranging the upper proximal pulley stack to have an axis that is offset from the axis of the lower proximal pulley stack standardizes the locations at which the cables exit the end effector, standardizes the cable exit locations and standardizes the impact of cable force to shaft deflection by making sure the cables are all the same distance from the shaft central axis and minimizes the likelihood that the cables routed around the pulleys will rub against internal edges in the instrument shaft. 
     Referring again to  FIG. 10 , a clevis cover  468  (see also  FIG. 17 ) covers a portion of the link  410 . The clevis cover is an insulating plastic part that helps to guide the cables to their intended locations in the shaft. The link  410  extends proximally into the instrument shaft  402 , which is preferably a rigid shaft. The proximal end of the shaft  402  is shown in  FIG. 23 , which shows that the cables exit the shaft  402  via a seal  470  that includes passages for each of the cables. This seal functions as an assembly tool during the assembly process, by helping align the cables. During the final stages of assembly, it is compressed to create one or more seals against the adjacent shaft and end cap components. During use of the instrument in surgery, the seals helps to prevent loss of pneumoperitoneum through leakage of gas through instrument shaft. 
     The proximal ends of the drive cables are engaged with actuators that may be disposed in a housing supported at the proximal end of the shaft  402 . These actuators are driven by or receive mechanical input from drive motors disposed within a component of the robotic surgical system that receives the instrument, such as the terminal portion of the robotic arm. One configuration is shown in commonly owned co-pending application Ser. No. 16/732,307, filed Dec. 31, 2019, entitled Compact Actuation Configuration and Expandable Instrument Receiver for Robotically Controlled Surgical Instruments, which is incorporated herein by reference. The actuators may be configured to receive linear and/or rotational drive input to selectively alter the tension on the drive cables, resulting in movement of the jaws and/or link  412 . 
     In use, actuation of the cables in the manner described with respect to the first embodiment produces the types of motion (pitch, yaw and jaw open-close) delineated in that description, and reference should be made to that discussion for details pertaining to those types of motion. As with that embodiment, pitch motion and jaw open-close motion occurs about the axis of pin  416  that extends through the pulleys defined by the lateral and medial pulley sections of each jaw member assembly. Yaw motion occurs about the axis of the pin  428  extending through distal pulleys  428   a - d.    
     Third Embodiment 
     A “fleet angle” is an angle between the cable and the plane that the corresponding pulley is rotating on. Referring to  FIG. 26 , each cable has a relatively large fleet angle F as it transitions from a jaw member to one of the distal pulleys  428   a - d , deviating from its original plane. Although fleet angle can be avoided using smaller pulleys, larger diameter pulleys have advantages, such as improved efficiency; smaller pulleys may necessitate stronger (and thus more expensive) cables than are needed with relatively larger pulleys. A third embodiment is a modified version of the first or second embodiment, and it includes features designed to minimize the impact of this fleet angle on tendon wear. In this embodiment, each distal pulley  428   a - d  is angled so that its distal-most edge is positioned laterally further from the longitudinal axis than its proximal-most edge. This may be achieved in a variety of ways. As a first example, the bosses  431  on the distal link  412  ( FIG. 18 ) can be made to be angularly oriented, such that their free ends are more proximal to their base. One example of the use of angled bosses  431   a  on the distal link  412  is shown in  FIG. 24A . Each boss  431   a  therefore has an axis (the axis of rotation of the pulleys that are mounted to that boss), that angles proximally from its point of intersection with the tab  430   a  as it extends away from tab  430   a .  FIG. 25  shows the distal pulleys  428   a - d  mounted to the angled bosses  431   a  and thus angled in a proximal direction. The proximal pulleys  429   a - d  are shown mounted on the pins  426  and maintaining a parallel relationship (parallel to the longitudinal axis of the instrument). 
     As an alternative to the use of the angled bosses, the angle of the cables at the yaw pulleys could be achieved by opening the tolerance between each yaw pulley  428   a - d  and its corresponding boss, allowing each of the pulleys  428   a - d  to tilt on its axis. 
     Other modifications designed to reduce the angle of the cables may be made in addition to, or as alternatives to, those described in this section. For example, the angle can be reduced by increasing the distance between the axes of the distal pulleys  428   a - d  and the axes of the proximal pulleys  429   a - d , and/or the radius of the pulley portion of each jaw member assembly may be reduced. 
     While certain embodiments have been described above, it should be understood that these embodiments are presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. Moreover, features of the different embodiments can be combined in different ways to produce other, different, embodiments. This is especially true in light of technology and terms within the relevant art(s) that may be later developed. Moreover, features of the various disclosed embodiments may be combined in various ways to produce various additional embodiments. 
     Any and all patents, patent applications and printed publications referred to above, including for purposes of priority, are incorporated herein by reference.