Patent Publication Number: US-2021169591-A1

Title: Surgical robotic systems

Description:
BACKGROUND 
     Surgical robotic systems have been used in minimally invasive medical procedures. Some surgical robotic systems included a console supporting a surgical robotic arm and a surgical instrument having at least one end effector (e.g., forceps or a grasping tool) mounted to the robotic arm. The robotic arm provided mechanical power to the surgical instrument for its operation and movement. 
     Manually-operated surgical instruments often included a handle assembly for actuating the functions of the surgical instrument. However, when using a robotic surgical system, no handle assembly was typically present to actuate the functions of the end effector. Accordingly, to use each unique surgical instrument with a robotic surgical system, an instrument drive unit was used to interface with the selected surgical instrument to drive operations of the surgical instrument. 
     The instrument drive unit was typically coupled to the robotic arm via a slide. The slide allowed the instrument drive unit and the attached surgical instrument to move along an axis of the slide, providing a means for adjusting the axial position of the end effector of the surgical instrument relative to a patient. 
     SUMMARY 
     In accordance with an aspect of the present disclosure, a surgical robotic system is provided and includes an elongated slide defining a longitudinal axis, a carriage for supporting an instrument drive unit, a drive motor, and a motor release mechanism. The carriage is coupled to the slide and movable relative thereto along the longitudinal axis. The drive motor is operably coupled to the carriage and configured to drive the movement of the carriage relative to the slide. The motor release mechanism is configured to selectively disengage the drive motor from the carriage to permit a manual movement of the carriage along the slide. 
     In aspects, the system may further include a pulley that operably couples the drive motor and the carriage. An activation of the motor release mechanism may disengage the pulley from the drive motor. 
     In certain aspects, the system may further include a motor output member rotatable by the drive motor. An activation of the motor release mechanism may slide the pulley relative to the motor output member from a first position to a second position. In the first position, the pulley and the motor output member are rotatable with one another, and in the second position the pulley is independently rotatable relative to the motor output member. 
     The system may further include a torque transfer pin non-rotatably coupling the pulley with the motor output member. The pulley may be configured to slide between the first and second positions along the torque transfer pin. 
     In aspects, the system may further include a one way bearing disposed between the pulley and the motor output member. The one way bearing may be configured to allow rotation of the pulley relative to the motor output member in a first direction, and resist rotation of the pulley relative to the motor output member in a second direction. 
     The one way bearing may be disposed within the pulley, and the motor output member may extend through the one way bearing and the pulley. 
     In certain aspects, the one way bearing may be non-rotationally fixed to the motor output member. 
     In aspects, the motor release mechanism may include a hub axially retained with the pulley and threadedly coupled to the motor output member. A rotation of the hub may move the pulley relative to the motor output member between the first and second positions. 
     The motor release mechanism may further include a knob configured to slide into and out of non-rotatable engagement with the hub. 
     In aspects, the system may further include a belt operably coupled to the pulley and fixed to the carriage, such that movement of the belt drives a movement of the carriage along the side. 
     The system may further include a robotic arm having the slide coupled thereto. 
     In another aspect of the present disclosure, a surgical robotic system includes a robotic arm, an elongated slide coupled to an end portion of the robotic arm, a drive motor, a pulley, and a motor release mechanism. The pulley is operably coupled to the drive motor and configured to drive a movement of an instrument drive unit along the slide. The motor release mechanism is configured to selectively disengage the pulley from the drive motor to permit a manual rotation of the pulley relative to the drive motor. 
     The system may further include a belt operably coupled to the pulley and fixedly coupled to an instrument drive unit, such that movement of the belt drives a movement of an instrument drive unit along the side. 
     Further details and aspects of exemplary embodiments of the present disclosure are described in more detail below with reference to the appended figures. 
     As used herein, the terms parallel and perpendicular are understood to include relative configurations that are substantially parallel and substantially perpendicular up to about + or −10 degrees from true parallel and true perpendicular. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present disclosure are described herein with reference to the accompanying drawings, wherein: 
         FIG. 1  is a schematic illustration of a surgical robotic system including an instrument drive unit coupled to a slide in accordance with the present disclosure; 
         FIG. 2  is a front view of the instrument drive unit and an associated surgical instrument coupled to an exemplary embodiment of a slide; 
         FIG. 3  is a side view, with parts removed, of a carriage coupled to the slide of  FIG. 2 ; 
         FIG. 4  is a front view, with parts removed, of the carriage coupled to the slide; 
         FIG. 5  is a side view of the slide, with an outer shaft of the slide shown in phantom, illustrating an inner shaft of the slide; 
         FIG. 6  is a side view of the slide, illustrating a belt and pulley system of the surgical robotic system; 
         FIG. 7  is a side perspective view, with parts removed, of the carriage coupled to the slide, illustrating the slide in an extended configuration and the carriage in an ascended position; 
         FIG. 8  is a perspective view of the slide coupled to a portion of a robotic arm, illustrating a motor release mechanism for use with the belt and pulley system of  FIG. 6 ; 
         FIG. 9  is a cross-sectional view, taken along line  9 - 9  in  FIG. 8 , of components of the motor release mechanism of  FIG. 8  and the belt and pulley system of  FIG. 6 ; 
         FIG. 10A  is a cross-sectional view of components of the motor release mechanism of  FIG. 8  and the belt and pulley system of  FIG. 6 , illustrating the motor release mechanism in an inactivated state; and 
         FIG. 10B  is a cross-sectional view of components of the motor release mechanism of  FIG. 8  and the belt and pulley system of  FIG. 6 , illustrating the motor release mechanism in an activated state. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the presently disclosed surgical robotic system and methods of use thereof are described in detail with reference to the drawings, in which like reference numerals designate identical or corresponding elements in each of the several views. As used herein, the term “proximal” refers to that portion of the surgical robotic system or component thereof that is closest to the clinician, while the term “distal” refers to that portion of the surgical robotic system or component thereof further from the clinician. 
     As will be described in detail below, provided is a surgical robotic system including a robotic arm, an elongated slide or rail coupled to the robotic arm, a belt and pulley system for driving movement of an instrument drive unit along the slide, and a motor release mechanism for selectively disengaging the belt and pulley system from a drive motor. During an emergency (e.g., a power outage), the motor release mechanism may be activated to allow for manual movement of the instrument drive unit along the slide. The motor release mechanism includes a one way bearing that allows for manual movement of the instrument drive unit in the direction away from a patient and resists manual movement of the instrument drive unit in a direction toward the patient. 
     Referring initially to  FIG. 1 , a surgical system, such as, for example, a surgical robotic system  1 , generally includes a plurality of surgical robotic arms  2 ,  3  having an instrument drive unit  20  and an electromechanical instrument  10  removably attached thereto; a control device  4 ; and an operating console  5  coupled with control device  4 . Operating console  5  includes a display device  6 , which is set up in particular to display three-dimensional images; and manual input devices  7 ,  8 , by means of which a person (not shown), for example a surgeon, is able to telemanipulate robotic arms  2 ,  3  in a first operating mode, as known in principle to a person skilled in the art. 
     Each of the robotic arms  2 ,  3  may be composed of a plurality of members, which are connected through joints. Robotic arms  2 ,  3  may be driven by electric drives (not shown) that are connected to control device  4 . Control device  4  (e.g., a computer) is set up to activate the drives, in particular by means of a computer program, in such a way that robotic arms  2 ,  3 , the attached instrument drive units  20 , and thus electromechanical instrument  10  execute a desired movement according to a movement defined by means of manual input devices  7 ,  8 . Control device  4  may also be set up in such a way that it regulates the movement of robotic arms  2 ,  3  and/or of the drives. 
     Surgical robotic system  1  is configured for use on a patient “P” lying on a surgical table “ST” to be treated in a minimally invasive manner by means of a surgical instrument, e.g., electromechanical instrument  10 . Surgical robotic system  1  may also include more than two robotic arms  2 ,  3 , the additional robotic arms likewise being connected to control device  4  and being telemanipulatable by means of operating console  5 . A surgical instrument, for example, an electromechanical surgical instrument  10  (including an electromechanical end effector (not shown)), may also be attached to the additional robotic arm. 
     Control device  4  may control a plurality of motors, e.g., motors (Motor 1 . . . n), with each motor configured to drive movement of robotic arms  2 ,  3  in a plurality of directions. Further, control device  4  may control a plurality of motors (not explicitly shown) of instrument drive unit  20  to drive various operations of surgical instrument  10 . The instrument drive unit  20  transfers power and actuation forces from its motors to driven members (not shown) of the electromechanical instrument  10  to ultimately drive movement of components of the end effector (not shown) of the electromechanical instrument  10 , for example, a movement of a knife blade (not shown) and/or a closing and opening of jaw members (not shown) of the end effector. 
     For a more detailed description of the construction and operation of components of an exemplary robotic surgical system, reference may be made to U.S. Pat. No. 8,828,023, entitled “Medical Workstation,” (hereinafter, “the &#39;023 patent”), and International Patent Publication WO2017/205308A1, entitled “Robotic Surgical Assemblies,” filed on May 23, 2017, (hereinafter, “the &#39;308 Publication”), the entire contents of each of which are incorporated by reference herein. 
     With reference to  FIGS. 2-7 , the surgical robotic system  1  includes a carriage  30  on which the instrument drive unit  20  is supported or carried, and the slide  100 , which supports the carriage  30 . The carriage  30  is configured to fix the instrument drive unit  20  thereto, such that movement of the carriage  30  along and relative to the slide  100  causes the instrument drive unit  20  to move therewith. The carriage  30  is slidably coupled to a linear track  102  defined longitudinally along an outer sleeve  106  of the slide  100 , as will be described below. 
     The slide  100  may have a generally rectangular shape and is constructed from an inner shaft  104  and an outer sleeve or sheath  106  disposed around the inner shaft  104 . In embodiments, the slide  100  may assume any suitable shape, such as, for example, tubular or cylindrical. The inner shaft  104  is coupled to an end of the robotic arm  2  ( FIG. 1 ) either in a fixed or rotatable manner. The inner shaft  104  has a bottom end portion  140   a  and a top end portion  104   b  and defines a longitudinal axis “X” therebetween. The inner shaft  104  may have an overall length approximately equal to half the length of a conventional slide. 
     The outer sleeve  106  of the slide  100  is disposed about the inner shaft  104  and is telescopically coupled thereto. As such, the outer sleeve  106  is slidable along and relative to the longitudinal axis “X” of the inner shaft  104  between a retracted position, as shown in  FIG. 3 , and an extended position, as shown in  FIG. 7 . When the outer sleeve  106  is in the retracted position, the slide has a first length “L 1 ” ( FIG. 3 ), substantially equal to approximately half the length of a conventional slide (e.g., as shown and described in the &#39;023 patent, and the &#39;308 Publication), and when the outer sleeve is in the extended position, the slide  100  has a second length “L 2 ” ( FIG. 7 ), substantially equal to approximately the full length of a conventional slide. 
     The outer sleeve  106  of the slide  100  defines a longitudinally-extending track  102 . The track  102  of the outer sleeve  106  may be a single rail or a pair of parallel rails. As mentioned above, the carriage  30  is slidably coupled to the track  102  of the outer sleeve  106 . More specifically, the carriage  30  has a coupling member or flange  32  extending from a back side thereof and through an elongated slot  108  of the outer sleeve  106 . The coupling member  32  of the carriage  30  is received in an interior chamber  110  ( FIG. 7 ) of the outer sleeve  106  and is fixed to a belt or cable  112  of a belt and pulley system  114  of the slide  100  for driving the movement of the carriage  30  between the ascended and descended positions, as will be described in detail. 
     The elongated slot  108  is defined along the length of the outer sleeve  106  and runs parallel with the track  102  between a bottom end portion  106   a  of the outer sleeve  106  and a top end portion  106   b  of the outer sleeve  106 . The elongated slot  108  of the outer sleeve  106  has an upper limit defining a surface feature  116  that prevents the carriage  30  from ascending beyond the upper limit. In embodiments, the surface feature  116  may be a projection extending outwardly from the top end portion  106   b  of the outer sleeve  106 . Upon the coupling member  32  of the carriage  30  contacting the surface feature  116 , a threshold force exerted on the carriage  30  in an upward direction causes the outer sleeve  106  to rise relative to the inner shaft  104 . 
     The top end portion  106   b  may further include a locking feature  118 , such as, for example, a roller catch, a magnetic latch, or the like. The locking feature  118  is configured to selectively lock the carriage  30  to the top end portion  106   b  of the outer sleeve  106  when the carriage  30  enters the ascended position. As such, with the outer sleeve  106  in the extended position relative to the inner shaft  104 , as shown in  FIG. 7 , a downward force exerted on the carriage  30  via the belt  112  causes the outer sleeve  106  to move downwardly with the carriage  30  due to the locking feature  118  locking the outer sleeve  106  and the carriage  30  to one another. Upon the bottom end portion  106   a  of the outer sleeve  106  bottoming out on the bottom end portion  104   a  of the inner shaft  104 , the locking feature  118  releases the carriage  30  to allow the carriage  30  to descend along the track  102  of the outer sleeve  106 . 
     With reference to  FIGS. 5-7 , the belt and pulley system  114  or drivetrain of the slide  100  is illustrated. The drivetrain  114  is operably coupled to a drive motor  120  disposed in the bottom end portion  104   a  of the inner shaft  104 . The drivetrain  114  includes a pair of first and second pulleys  114   a ,  114   b  coupled to the outer shaft  106 , and a third pulley  114   c  coupled to the inner shaft  104 . The first pulley  114   a  is axially fixed and rotatably coupled to the top end portion  106   b  of the outer sleeve  106  of the slide  100 , and the second pulley  114   b  is axially fixed and rotatably coupled to the bottom end portion  10   ba  of the outer sleeve  106 . As such, as the outer sleeve  106  moves relative to the inner shaft  104  toward the extended position, the first and second pulleys  114   a ,  114   b  move therewith. The third pulley  114   c  is axially fixed and rotatably coupled to the top end portion  104   b  of the inner shaft  104 . 
     The second pulley  114   b  is disposed between the first and third pulleys  114   a ,  114   c  and is longitudinally spaced from the first pulley  114   a  along the length of the outer sleeve  106 . As shown in  FIG. 5 , when the outer sleeve  106  is in the retracted position, the first and third pulleys  114   a ,  114   c  are disposed adjacent one another, with the second pulley  114   b  longitudinally spaced from the third pulley  114   c . As shown in  FIG. 7 , when the outer sleeve  106  is in the extended position, the first and third pulleys  114   a ,  114   c  are longitudinally spaced from one another, with the second and third pulleys  114   b ,  114   c  proximate to one another. 
     With specific reference to  FIG. 6 , the second pulley  114   b  is positioned relative to the first and third pulleys  114   a ,  114   c  so that a net downward force, in the direction indicated by arrow “A” in  FIG. 6 , is exerted on the outer sleeve  106 . In particular, the second pulley  114   b  has a vertical axis “Y” extending through a center point thereof and parallel with the longitudinal axis “X” ( FIG. 2 ) of the inner shaft  104 . The first pulley  114   a  is disposed a first distance “d 1 ” from the vertical axis “Y” in a transverse direction, and the third pulley  114   c  is disposed a second distance “d 2 ” from the vertical axis “Y” in the transverse direction, less than the first distance “d 1 .” Accordingly, a first portion “P 1 ” of the belt  112  extends from the second pulley  114   b  to the first pulley  114   a  at an angle greater than an angle at which a second portion “P 2 ” of the belt  112  extends from the second pulley  114   b  to the third pulley  114   c . Due to the difference in these angles, the downward force exerted by the first pulley  114   a  on the outer sleeve  106  is greater than the upward force exerted by the third pulley  114   c  on the outer sleeve  106 , whereby the outer sleeve  106  has a constant net downward force imparted thereon. Stated differently, a sum of all of the Y-components of force acting on first portion “P 1 ” of belt  112 , and second portion “P 2 ” of belt  112 , due to the angles of inclination of first portion “P 1 ” and second portion “P 2 ” of belt  112 , is such that there is constant net downward force imparted on outer sleeve  106 . 
     The belt  112  is operably coupled to the drive motor  120 , via a main pulley  123  ( FIG. 9 ), and each of the first, second, and third pulleys  114   a - c . The belt  112  is wrapped over the first pulley  114   a , under the second pulley  114   b , and over the third pulley  114   c . The belt  112  is driven by the motor  120  and is fixed to the coupling member  32  of the carriage  30 , such that an activation of the motor  120  causes the belt  112  to move around the pulleys  114   a - c  and move the attached carriage  30  along the outer sleeve  106  either toward the ascended position or the descended position. 
     In operation, prior to performing a surgical procedure, the instrument dive unit  20  may be attached to the carriage  30 , and the electromechanical instrument  10  may be attached to the instrument drive unit  20 . With the instrument drive unit  20  and the associated electromechanical instrument  10  attached to the carriage  30 , a longitudinal position (e.g., height) of the carriage  30  along the longitudinal axis “X” may be adjusted. For example, to raise the carriage  30 , the motor  120  of the slide  100  is activated to move the belt  112  upwardly relative to the outer sleeve  106  of the slide  100 . The carriage  30  is raised to the ascended position and contacts the locking feature  118  and/or the surface feature  116  of the top end portion  106   b  of the outer sleeve  106 . With the carriage  30  fixed to the top end portion  106   b  of the outer sleeve  106 , an activation of the motor  120  causes the carriage  30  to exert an upward force on the outer sleeve  106  to move the outer sleeve  106  upwardly relative to the inner shaft  104 . As the outer sleeve  106  moves, the first and second pulleys  114   a ,  114   b  move therewith and relative to the third pulley  114   c . In the fully extended position, as shown in  FIG. 7 , the slide  100  assumes a length substantially equal to the length of a conventional slide. 
     To lower the carriage  30  from the extended position, the motor  120  is activated to drive the belt  112  in the opposite direction. In the embodiment where the locking feature  118  fixes the carriage  30  to the top end portion  106   b  of the outer sleeve  106  of the slide  100 , the downward force exerted on the carriage  30 , via the belt  112 , causes the outer sleeve  106  to retract relative to the inner shaft  104 . The outer sleeve  106  may be retracted until the bottom end portion  106   a  of the outer sleeve  106  bottoms out on the bottom end portion  104   a  of the inner shaft  104 . At this point, to further lower the carriage  30 , the belt  112 , via the motor  120 , exerts a force great enough to unlock the carriage  30  from the top end portion  106   a  of the outer sleeve  106 , whereby the carriage  30  descends along the track  102  of the outer sleeve  106  toward the descended position, as shown in  FIGS. 3-5 . 
     With reference to  FIGS. 8-10B , the slide  100  may further include a motor release mechanism  200  for manually disengaging the main pulley  123  of the belt and pulley system  114  ( FIG. 5 ) from the drive motor  120  to allow a clinician to manually move the carriage  30  and associated instrument drive unit  20  and surgical instrument  10  to a safe position away from the position during an emergency situation (e.g., a power outage). 
     The motor release mechanism  200  generally includes a hub  202  and a knob  204 . The hub  202  is threadedly coupled to a threaded outer surface  130  of a motor output member  132 , and the knob  204  is slidably coupled to the hub  202 . The knob  204  protrudes outwardly from the slide  100  to provide access to the knob  204 . To activate the motor release mechanism  200 , the knob  204  is pushed inwardly, in the direction indicated by arrow “B” in  FIG. 9 , which non-rotationally fixes the knob  204  to the hub  202  in a friction fit engagement. With the knob  204  non-rotationally fixed to the hub  202 , a rotation of the knob  204  rotates the hub  202  relative to the motor output member  132 . As the motor release mechanism  200  is rotated, the motor release mechanism  200  is pulled along the motor output member  132 , in the direction indicated by arrow “C.” In embodiments, the knob  204  may be permanently non-rotatably coupled to the hub  202  to remove the safety step of pushing the knob  204  into engagement with the hub  202  prior to activating the motor release mechanism  200 . 
     The hub  202  of the motor release mechanism  200  is axially retained within a proximal end  123   a  of the pulley  123  while also being permitted to rotate relative to the pulley  123 . A thrust bearing  133  may be provided to facilitate rotation of the hub  202  within and relative to the pulley  132 . Due to the hub  202  being axially retained within the pulley  123 , as the hub  202  of the motor release mechanism  200  is moved in direction “C,” so is the pulley  123 . 
     The motor output member  132  of the belt and pulley system  114  includes a casing  132   a  and a shaft  132   b  extending from the casing  132   a . The shaft  132   b  is non-rotationally fixed to a motor gearbox output shaft  125  of the drive motor  120  and extends axially through the pulley  123 . A pair of torque transfer pins  134   a ,  134   b  are fixed to the casing  132   a  and extend through corresponding bores  127   a ,  127   b  defined through a distal end  123   b  of the pulley  123 . In embodiments, there may be more or less than two pins  134   a ,  134   b . The torque transfer pins  134   a ,  134   b  drivingly couple the pulley  123  to the motor output member  132 , such that the pulley  123  rotates with the motor output member  132  in response to an activation of the drive motor  120 . 
     The pulley  123  is slidable relative to and along the pins  134   a ,  134   b  to adjust an axial position of the pulley  123  relative to the motor output member  132 . In particular, the pulley  123  is axially movable along the torque transfer pins  134   a ,  134   b , in response to an activation of the motor release mechanism  200 , between a first axial position, as shown in  FIG. 10A , and a second axial position, as shown in  FIG. 10B . In the first axial position, the torque transfer pins  134   a ,  134   b  extend through the bores  127   a ,  127   b  of the pulley  123 , non-rotationally fixing the pulley  123  with the motor output member  132 . In the second axial position, the pulley  123  is disengaged from the torque transfer pins  134   a ,  134   b , whereby the pulley  123  is decoupled from the motor output member  123  and independently rotatable relative to the motor output member  132 . The slide  100  may include a spring  135  (e.g., a wave spring) that resiliently biases the pulley  123  toward the first position. A thrust bearing  137  may be provided to facilitate rotation of the pulley  123  relative to the spring  135 . 
     The slide  100  further includes a one way bearing  138  disposed within the pulley  123  and captured between the pulley  123  and the shaft  132   b  of the motor output member  132 . The bearing  138  may be non-rotationally fixed to the shaft  132   b  of the motor output member  132 . The bearing  138  may be any suitable one way bearing or clutch, such as, for example, a one way bearing having rollers, sprags, or spring elements. The bearing  138  is configured to resist rotation of the pulley  123  relative to the motor output member  132  in the direction corresponding to a movement of the carriage  30 /instrument drive unit  20  in a downward direction along the slide  100 , as described below. 
     In operation, when the pulley  123  is in the first or operational position, as shown in  FIG. 10A , an activation of the drive motor  120  rotates the motor output member  132 , the bearing  138 , and the pulley  123  as one integral unit in either rotational direction (i.e., clockwise or counter-clockwise). As described above, a rotation of the pulley  123  results in a movement of the surgical instrument  10  along the slide  100  in a selected direction. For example, a clockwise rotation of the pulley  123  may result in an upward movement of the surgical instrument  10  along the slide  100 , whereas a counter-clockwise rotation of the pulley  123  may result in a downward movement of the surgical instrument  10  along the slide. 
     During an emergency (e.g., a power outage), a clinician may desire to move the surgical instrument  10  out of and away from the patient. However, during a power outage, the drive motor  120  will be locked out and prevent a manual movement of the surgical instrument  10  along the slide  100 . Accordingly, to move the surgical instrument  10 /carriage  30 /instrument drive unit  20 , the carriage  30  may need to be operably disengaged from the drive motor  120 . 
     To disengage the drive motor  120  from the carriage  20 , the motor release mechanism  200  may be actuated by pushing the knob  204  thereof into non-rotational engagement with the hub  202  thereof. With the knob  204  and hub  202  of the motor release mechanism  200  non-rotationally coupled to one another, the knob  204  and hub  202  are rotated together about the motor output member  132  to draw the pulley  123  away from the casing  132   a  of the motor output member  132  toward the second position, whereby the belt and pulley system  114  ( FIG. 5 ) is disengaged from the drive motor  120 . 
     When the pulley  123  is in the second or safety position, as shown in  FIG. 10B , the bearing  138  permits a rotation of the pulley  123  relative thereto and relative to the motor output member  132  in the direction corresponding to movement of the carriage  30 /instrument drive unit  20 /surgical instrument  10  in an upward direction along the slide  100 . Accordingly, the surgical instrument  10  may be manually moved up and out of the patient to a selected position along the slide  100 . In contrast, an attempt to move the carriage  30 /instrument drive unit  20 /surgical instrument  10  in the downward direction is thwarted due to the one way bearing  138  preventing rotation of the pulley  123  relative to the bearing  138  in the corresponding rotational direction. Further, since the drive motor  120  is in a locked state (e.g., due to a power outage), the drive motor  120  prevents the bearing  138  and the motor output member  132  from being rotated by the applied force on the carriage  30 /instrument drive unit  20 /surgical instrument  10 . 
     It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of various embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended thereto.