Surgical robotic system and method for sensing cable-driven instrument failure and detachment

Abstract

A surgical robotic system includes an instrument drive unit having a plurality of motors, each of which includes a torque sensor for measuring a torque of a corresponding motor of the plurality of motors. The system also includes an instrument coupled to the instrument drive unit. The instrument includes an end effector, and a plurality of cables, each of which is coupled to and movable by one motor of the plurality of motors to actuate the end effector. The system further includes a controller configured to calculate a torque threshold corresponding to at least one of failure of the instrument or detachment from the instrument drive unit, activate at least one motor of the plurality of motors to actuate the end effector, and measure torque of each motor of the plurality of motors during activation of the at least one motor. The controller is further configured to calculate an average torque value based on measured torque of each motor of the plurality of motors, compare the average torque value to the torque threshold, and output an alert in response to the average torque value being below the torque threshold.

Description

SURGICAL ROBOTIC SYSTEM AND METHOD FOR SENSING CABLE-DRIVEN INSTRUMENT FAILURE AND DETACHMENTCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 572,417 filed April 1, 2024, the entire content of which is incorporated herein by reference.BACKGROUND

[0002] Surgical robotic systems are currently being used in a variety of surgical procedures, including minimally invasive medical procedures. Some surgical robotic systems include a surgeon console controlling a surgical robotic arm and a surgical instrument having an end effector (e.g., forceps or grasping instrument) coupled to and actuated by the robotic arm. In operation, the robotic arm is moved to a position over a patient and then guides the surgical instrument into a small incision via a surgical port or a natural orifice of a patient to position the end effector at a work site within the patient’s body.

[0003] Surgical robotic instruments may include various jawed instruments such as graspers, vessel sealers, and shears. The instruments may be coupled to an instrument drive unit having one or more motors. The instruments may be actuated by one or more cables, which are used to open or close jaws as well as change pitch and yaw direction of the jaws. During actuation of the jaws various parameters may be measured, which may be used to control the surgical instrument. For safety reasons, it is important to detect instrument failure or detachment of the instrument from the instrument drive unit during a surgical procedure. The detection of this type of failure may be used to generate an appropriate system response to prevent injury to the patient and / or damage to the system.SUMMARY

[0004] The present disclosure provides for a surgical robotic system including a robotic arm having an instrument drive unit (IDU) with a plurality of motors (e.g., four). A wristed surgical instrument is coupled to and is actuated by the IDU. The instrument includes a wristed end effector, which may be a jaw-type instrument, such as a grasper, a shears, and the like. The end effector is actuated by a plurality of cables (e.g., four), each of which ismoved by a corresponding motor via a threaded coupler. The wristed instrument is an openchain manipulator and the coordinated motion of four drive cables generates yaw and pitch articulation as well as jaw actuation. A drive transmission within the instrument converts the rotary motion of four motors in the drive unit into rectilinear motion of the four drive cables. This is in contrast to closed-chain architecture wristed instruments, where there may be three closed chains - one for each jaw and another for yaw.

[0005] One beneficial feature of the open-chain manipulator control scheme is that it implicitly enforces the maintenance of cable tension, as long as there is tension in the cables when the zero position of the motors is set. Tension is maintained during use because the motor positions are commanded differentially - if one cable is pulled by some displacement, another is released by the same amount. This suggests an analogy to closed-chain manipulators - whereas the cable tension in closed-chain manipulators is locked in during manufacturing, the cable tension in open-chain manipulators with this control scheme can be locked in at the beginning of each use, during a calibration routine.

[0006] The present disclosure provides for an additional monitoring feature, which may be embodied as software instructions stored in memory and executable by one or more processors of the robotic system. The monitoring feature includes receiving torque sensor readings from each torque sensor of each motor in the IDU. The processor then calculates the average of the four torque sensor measurements. When the instrument breaks or is detached from the IDU, the average torque drops dramatically, as tension in the cables drops. The average torque is compared to a threshold indicative of failure or detachment, and if the average torque is below the threshold, then the processor determines that the instrument has failed and / or detached from the IDU. In response to this determination, the processor may take one or more remedial actions, such as output an alert to the system, write error to a log, automatically control the system to prevent further control of the instrument, automatically control the robotic arm and / or the instrument to extract the instrument, etc.

[0007] According to one embodiment of the present disclosure a surgical robotic system is disclosed. The system includes an instrument drive unit having a plurality of motors, each of which includes a torque sensor for measuring a torque of a corresponding motor of the plurality of motors. The system also includes an instrument coupled to the instrument drive unit. The instrument includes an end effector and a plurality of cables each of which is coupled to and movable by one motor of the plurality of motors to actuate the end effector.The system further includes a controller configured to calculate a torque threshold corresponding to at least one of failure of the instrument or detachment from the instrument drive unit, activate at least one motor of the plurality of motors to actuate the end effector, and measure torque of each motor of the plurality of motors during activation of the at least one motor. The controller is further configured to calculate an average torque value based on measured torque of each motor of the plurality of motors, compare the average torque value to the torque threshold, and output an alert in response to the average torque value being below the torque threshold.

[0008] Implementations of the above embodiment may include one or more of the following features. According to one aspect of the above embodiment, the controller may be further configured to calibrate the instrument drive unit with the instrument attached thereto or home each motor of the plurality of motors and to measure torque of each motor of the plurality of motors after calibration or homing. The controller may be also further configured to calculate a baseline average torque value based on measured torque of each motor of the plurality of motors after calibration or homing and to multiply the baseline average torque by a scaling factor to calculate the torque threshold. The scaling factor may be less than one. The surgical robotic system may also include a surgeon console which may include a handle controller for receiving input for actuating the end effector and a display screen for displaying the alert. The controller may be further configured to prevent actuation of the end effector by the handle controller in response to the average torque value being below the torque threshold.

[0009] According to another embodiment of the present disclosure, a method for detection of instrument failure or detachment from an instrument drive unit is disclosed. The method includes calculating a torque threshold corresponding to at least one of failure of the instrument or detachment from the instrument drive unit. The instrument drive unit includes a plurality of motors, each of which may include a torque sensor for measuring a torque of a corresponding motor of the plurality of motors. The instrument is coupled to the instrument drive unit and the instrument includes an end effector, a plurality of cables each of which is coupled to and movable by one motor of the plurality of motors to actuate the end effector. The method also includes activating at least one motor of the plurality of motors to actuate the end effector, and measuring torque of each motor of the plurality of motors during activation of the at least one motor. The method also includes calculating anaverage torque value based on measured torque of each motor of the plurality of motors, comparing the average torque value to the torque threshold, and outputting an alert in response to the average torque value being below the torque threshold.

[0010] Implementations of the above embodiment may include one or more of the following features. According to one aspect of the above embodiment, the method may also include calibrating the instrument drive unit with the instrument attached thereto or homing each motor of the plurality of motors, and measuring torque of each motor of the plurality of motors after calibration or homing. The method may further include calculating a baseline average torque value based on measured torque of each motor of the plurality of motors after calibration or homing, and multiplying the baseline average torque by a scaling factor to calculate the torque threshold. The method may also include receiving input at a handle controller for actuating the end effector, and displaying the alert on a display screen and preventing actuation of the end effector by the handle controller in response to the average torque value being below the torque threshold.

[0011] According to a further embodiment of the present disclosure, a surgical system is disclosed. The system includes an instrument drive unit having a plurality of motors, each of which includes a torque sensor for measuring a torque of a corresponding motor of the plurality of motors. The system includes an instrument coupled to the instrument drive unit. The instrument includes an end effector and a plurality of cables each of which is coupled to and movable by one motor of the plurality of motors to actuate the end effector. The system also includes a controller configured to calculate a torque threshold corresponding to at least one of failure of the instrument or detachment from the instrument drive unit, activate at least one motor of the plurality of motors to actuate the end effector, and determine whether the instrument is being teleoperated. While the instrument is being teleoperated, the controller is further configured to measure torque of each motor of the plurality of motors during activation of the at least one motor, calculate an average torque value based on measured torque of each motor of the plurality of motors, compare the average torque value to the torque threshold, and output an alert in response to the average torque value being below the torque threshold.

[0012] Implementations of the above embodiment may include one or more of the following features. According to one aspect of the above embodiment, the controller may be further configured to calibrate the instrument drive unit with the instrument attached thereto orhome each motor of the plurality of motors. The controller may be also configured to measure torque of each motor of the plurality of motors after calibration or homing. The controller may be additionally configured to calculate a baseline average torque value based on measured torque of each motor of the plurality of motors after calibration or homing, and to multiply the baseline average torque by a scaling factor to calculate the torque threshold.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Various embodiments of the present disclosure are described herein with reference to the drawings wherein:

[0014] FIG. 1 is a schematic illustration of a surgical robotic system including a control tower, a console, and one or more surgical robotic arms each disposed on a movable cart according to an embodiment of the present disclosure;

[0015] FIG. 2 is a perspective view of a surgical robotic arm of the surgical robotic system of FIG. 1 according to an embodiment of the present disclosure;

[0016] FIG. 3 is a perspective view of a movable cart having a setup arm with the surgical robotic arm of the surgical robotic system of FIG. 1 according to an embodiment of the present disclosure;

[0017] FIG. 4 is a schematic diagram of a computer architecture of the surgical robotic system of FIG. 1 according to an embodiment of the present disclosure;

[0018] FIG. 5 is a plan schematic view of movable carts of FIG. 1 positioned about a surgical table according to an aspect of the present disclosure;

[0019] FIG. 6 is a perspective view, with parts separated, of an instrument drive unit and a surgical instrument according to an embodiment of the present disclosure;

[0020] FIG. 7 is a top, perspective view of a grasper end effector, according to an embodiment of the present disclosure, for use in the surgical robotic system of FIG. 1 ;

[0021] FIG. 8 is a top, perspective view of a shears end effector, according to an embodiment of the present disclosure, for use in the surgical robotic system of FIG. 1 ;

[0022] FIG. 9 shows the grasper end effector in various configurations according to an embodiment of the present disclosure;

[0023] FIG. 10 is a flow chart of a method for detection of instrument failure and / or detachment from the IDU according to an embodiment of the present disclosure; and

[0024] FIG. 11 is a schematic diagram of a system for determining phases of a surgical procedure according to an embodiment of the present disclosure.DETAILED DESCRIPTION

[0025] Embodiments of the presently disclosed surgical robotic system 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.

[0026] As will be described in detail below, the present disclosure is directed to a surgical robotic system, which includes a surgeon console, a control tower, and one or more movable carts having a surgical robotic arm coupled to a setup arm. The surgeon console receives user input through one or more interface devices. The input is processed by the control tower as movement commands for moving the surgical robotic arm and an instrument and / or camera coupled thereto. Thus, the surgeon console enables teleoperation of the surgical arms and attached instruments / camera. The surgical robotic arm includes a controller, which is configured to process the movement commands and to generate a torque commands for activating one or more actuators of the robotic arm, which would, in turn, move the robotic arm in response to the movement commands.

[0027] With reference to FIG. 1, a surgical robotic system 10 includes a control tower 20, which is connected to all of the components of the surgical robotic system 10 including a surgeon console 30 and one or more movable carts 60. Each of the movable carts 60 includes a robotic arm 40 having a surgical instrument 50 coupled thereto. The robotic arms 40 also couple to the movable carts 60. The robotic system 10 may include any number of movable carts 60 and / or robotic arms 40.

[0028] The surgical instrument 50 is configured for use during minimally invasive surgical procedures. In embodiments, the surgical instrument 50 may be configured for open surgical procedures. In further embodiments, the surgical instrument 50 may be an electrosurgical forceps configured to seal tissue by compressing tissue between jaw members and applying electrosurgical current thereto. In yet further embodiments, the surgical instrument 50 may be a surgical stapler including a pair of jaws configured to grasp and clamp tissue while deploying a plurality of tissue fasteners, e.g., staples, and cutting stapled tissue. In yet further embodiments, the surgical instrument 50 may be a surgical clip applier including a pair of jaws configured to apply a surgical clip onto tissue. However, itwill be understood that various types of surgical instruments for use during minimally invasive surgical procedures are contemplated and within the scope of this disclosure.

[0029] One of the robotic arms 40 may include an endoscopic camera 51 configured to capture video of the surgical site. The endoscopic camera 51 may be a stereoscopic endoscope configured to capture two side-by-side (i.e., left and right) images of the surgical site to produce a video stream of the surgical scene. The endoscopic camera 51 is coupled to a video processing device 56, which may be disposed within the control tower 20. The video processing device 56 may be any computing device as described below configured to receive the video feed from the endoscopic camera 51 and output the processed video stream.

[0030] The surgeon console 30 includes a first display 32, which displays a video feed of the surgical site provided by camera 51 disposed on the robotic arm 40, and a second display 34, which displays a user interface for controlling the surgical robotic system 10. The first display 32 and second display 34 may be touchscreens allowing for displaying various graphical user inputs.

[0031] The surgeon console 30 also includes a plurality of user interface devices, such as foot pedals 36 and a pair of handle controllers 38a and 38b which are used by a user to remotely control robotic arms 40. The surgeon console further includes an armrest 33 used to support clinician’s arms while operating the handle controllers 38a and 38b.

[0032] The control tower 20 includes a display 23, which may be a touchscreen that may display the graphical user interfaces (GUIs). The control tower 20 also acts as an interface between the surgeon console 30 and one or more robotic arms 40. In particular, the control tower 20 is configured to control the robotic arms 40, such as to move the robotic arms 40 and the corresponding surgical instrument 50, based on a set of programmable instructions and / or input commands from the surgeon console 30, in such a way that robotic arms 40 and the surgical instrument 50 execute a desired movement sequence in response to input from the foot pedals 36 and the handle controllers 38a and 38b. The foot pedals 36 may be used to enable and lock the handle controllers 38a and 38b, repositioning camera movement and electrosurgical activation / deactivation. In particular, the foot pedals 36 may be used to perform a clutching action on the handle controllers 38a and 38b. Clutching is initiated by pressing one of the foot pedals 36, which disconnects (i.e., prevents movement inputs) the handle controllers 38a and / or 38b from the robotic arm 40 and corresponding instrument 50or camera 51 attached thereto. This allows the user to reposition the handle controllers 38a and 38b without moving the robotic arm(s) 40 and the instrument 50 and / or camera 51. This is useful when reaching control boundaries of the surgical space.

[0033] Each of the control tower 20, the surgeon console 30, and the robotic arm 40 includes a respective computer 21, 31, 41. The computers 21 , 31 , 41 are interconnected to each other using any suitable communication network based on wired or wireless communication protocols. The term “network,” whether plural or singular, as used herein, denotes a data network, including, but not limited to, the Internet, Intranet, a wide area network, or a local area network, and without limitation as to the full scope of the definition of communication networks as encompassed by the present disclosure. Suitable protocols include, but are not limited to, transmission control protocol / intemet protocol (TCP / IP), datagram protocol / intemet protocol (UDP / IP), and / or datagram congestion control protocol (DCCP). Wireless communication may be achieved via one or more wireless configurations, e.g., radio frequency, optical, Wi-Fi, Bluetooth (an open wireless protocol for exchanging data over short distances, using short length radio waves, from fixed and mobile devices, creating personal area networks (PANs), ZigBee® (a specification for a suite of high level communication protocols using small, low-power digital radios based on the IEEE 122. 15.4-1203 standard for wireless personal area networks (WPANs)).

[0034] The computers 21, 31, 41 may include any suitable processor (not shown) operably connected to a memory (not shown), which may include one or more of volatile, nonvolatile, magnetic, optical, or electrical media, such as read-only memory (ROM), random access memory (RAM), electrically erasable programmable ROM (EEPROM), non-volatile RAM (NVRAM), or flash memory. The processor may be any suitable processor (e.g., control circuit) adapted to perform the operations, calculations, and / or set of instructions described in the present disclosure including, but not limited to, a hardware processor, a field programmable gate array (FPGA), a digital signal processor (DSP), a central processing unit (CPU), a microprocessor, and combinations thereof. Those skilled in the art will appreciate that the processor may be substituted by using any logic processor (e.g., control circuit) adapted to execute algorithms, calculations, and / or set of instructions described herein.

[0035] With reference to FIG. 2, each of the robotic arms 40 may include a plurality of links 42a, 42b, 42c, which are interconnected at joints 44a, 44b, 44c, respectively. Otherconfigurations of links and joints may be utilized as known by those skilled in the art. The joint 44a is configured to secure the robotic arm 40 to the movable cart 60 and defines a first longitudinal axis. With reference to FIG. 3, the movable cart 60 includes a lift 67 and a setup arm 61, which provides a base for mounting of the robotic arm 40. The lift 67 allows for vertical movement of the setup arm 61. The movable cart 60 also includes a display 69 for displaying information pertaining to the robotic arm 40. In embodiments, the robotic arm 40 may include any type and / or number of joints.

[0036] The setup arm 61 includes a first link 62a, a second link 62b, and a third link 62c, which provide for lateral maneuverability of the robotic arm 40. The links 62a, 62b, 62c are interconnected at joints 63a and 63b, each of which may include an actuator (not shown) for rotating the links 62b and 62b relative to each other and the link 62c. In particular, the links 62a, 62b, 62c are movable in their corresponding lateral planes that are parallel to each other, thereby allowing for extension of the robotic arm 40 relative to the patient (e.g., surgical table). In embodiments, the robotic arm 40 may be coupled to the surgical table (not shown). The setup arm 61 includes controls 65 for adjusting movement of the links 62a, 62b, 62c as well as the lift 67. In embodiments, the setup arm 61 may include any type and / or number of joints.

[0037] The third link 62c may include a rotatable base 64 having two degrees of freedom. In particular, the rotatable base 64 includes a first actuator 64a and a second actuator 64b. The first actuator 64a is rotatable about a first stationary arm axis which is perpendicular to a plane defined by the third link 62c and the second actuator 64b is rotatable about a second stationary arm axis which is transverse to the first stationary arm axis. The first and second actuators 64a and 64b allow for full three-dimensional orientation of the robotic arm 40.

[0038] The actuator 48b of the joint 44b is coupled to the joint 44c via the belt 45a, and the joint 44c is in turn coupled to the joint 46b via the belt 45b. Joint 44c may include a transfer case coupling the belts 45a and 45b, such that the actuator 48b is configured to rotate each of the links 42b, 42c and a holder 46 relative to each other. More specifically, links 42b, 42c, and the holder 46 are passively coupled to the actuator 48b which enforces rotation about a pivot point “P” which lies at an intersection of the first axis defined by the link 42a and the second axis defined by the holder 46. In other words, the pivot point “P” is a remote center of motion (RCM) for the robotic arm 40. Thus, the actuator 48b controls the angle 0 between the first and second axes allowing for orientation of the surgical instrument 50.Due to the interlinking of the links 42a, 42b, 42c, and the holder 46 via the belts 45a and 45b, the angles between the links 42a, 42b, 42c, and the holder 46 are also adjusted in order to achieve the desired angle 0. In embodiments, some or all of the joints 44a, 44b, 44c may include an actuator to obviate the need for mechanical linkages.

[0039] The joints 44a and 44b include an actuator 48a and 48b configured to drive the joints 44a, 44b, 44c relative to each other through a series of belts 45a and 45b or other mechanical linkages such as a drive rod, a cable, or a lever and the like. In particular, the actuator 48a is configured to rotate the robotic arm 40 about a longitudinal axis defined by the link 42a.

[0040] With reference to FIG. 2, the holder 46 defines a second longitudinal axis and configured to receive an instrument drive unit (IDU) 52 (FIG. 1). The IDU 52 is configured to couple to an actuation mechanism of the surgical instrument 50 and the camera 51 and is configured to move (e.g., rotate) and actuate the instrument 50 and / or the camera 51. IDU 52 transfers actuation forces from its actuators to the surgical instrument 50 to actuate components of an end effector 49 of the surgical instrument 50. The holder 46 includes a sliding mechanism 46a, which is configured to move the IDU 52 along the second longitudinal axis defined by the holder 46. The holder 46 also includes a joint 46b, which rotates the holder 46 relative to the link 42c. During endoscopic procedures, the instrument 50 may be inserted through an endoscopic access port 55 (FIG. 3) held by the holder 46. The holder 46 also includes a port latch 46c for securing the access port 55 to the holder 46 (FIG. 2).

[0041] The IDU 52 is attached to the holder 46, followed by a sterile interface module (SIM) 43 being attached to a distal portion of the IDU 52. The SIM 43 is configured to secure a sterile drape (not shown) to the IDU 52. The instrument 50 is then attached to the SIM 43. The instrument 50 is then inserted through the access port 55 by moving the IDU 52 along the holder 46. The SIM 43 includes a plurality of drive shafts configured to transmit rotation of individual motors of the IDU 52 to the instrument 50 thereby actuating the instrument 50. In addition, the SIM 43 provides a sterile barrier between the instrument 50 and the other components of robotic arm 40, including the IDU 52.

[0042] The robotic arm 40 also includes a plurality of manual override buttons 53 (FIG. 1) disposed on the IDU 52 and the setup arm 61, which may be used in a manual mode. The user may press one or more of the buttons 53 to move the component associated with the one or more buttons 53.

[0043] With reference to FIG. 4, each of the computers 21, 31, 41 of the surgical robotic system 10 may include a plurality of controllers, which may be embodied in hardware and / or software. The computer 21 of the control tower 20 includes a controller 21a and safety observer 2 lb. The controller 21a receives data from the computer 31 of the surgeon console 30 about the current position and / or orientation of the handle controllers 38a and 38b and the state of the foot pedals 36 and other buttons. The controller 21a processes these input positions to determine desired drive commands for each joint of the robotic arm 40 and / or the IDU 52 and communicates these to the computer 41 ofthe robotic arm 40. The controller 21a also receives the actual joint angles measured by encoders of the actuators 48a and 48b and uses this information to determine force feedback commands that are transmitted back to the computer 31 of the surgeon console 30 to provide haptic feedback through the handle controllers 38a and 38b. The safety observer 2 lb performs validity checks on the data going into and out of the controller 21a and notifies a system fault handler if errors in the data transmission are detected to place the computer 21 and / or the surgical robotic system 10 into a safe state.

[0044] The computer 41 includes a plurality of controllers, namely, a main cart controller 41a, a setup arm controller 41b, a robotic arm controller 41c, and an instrument drive unit (IDU) controller 4 Id. The main cart controller 41a receives and processes joint commands from the controller 21a of the computer 21 and communicates them to the setup arm controller 41b, the robotic arm controller 41c, and the IDU controller 4 Id. The main cart controller 41a also manages instrument exchanges and the overall state of the movable cart 60, the robotic arm 40, and the IDU 52. The main cart controller 41a also communicates actual joint angles back to the controller 21a.

[0045] Each of joints 63a and 63b and the rotatable base 64 of the setup arm 61 are passive joints (i.e., no actuators are present therein) allowing for manual adjustment thereof by a user. The joints 63a and 63b and the rotatable base 64 include brakes that are disengaged by the user to configure the setup arm 61. The setup arm controller 4 lb monitors slippage of each ofjoints 63a and 63b and the rotatable base 64 ofthe setup arm 61, when brakes are engaged or can be freely moved by the operator when brakes are disengaged, but do not impact controls of other joints. The robotic arm controller 41c controls each joint 44a and 44b of the robotic arm 40 and calculates desired motor torques required for gravity compensation, friction compensation, and closed loop position control of the robotic arm40. The robotic arm controller 41c calculates a movement command based on the calculated torque. The calculated motor commands are then communicated to one or more of the actuators 48a and 48b in the robotic arm 40. The actual joint positions are then transmitted by the actuators 48a and 48b back to the robotic arm controller 41c.

[0046] The IDU controller 4 Id receives desired joint angles for the surgical instrument 50, such as wrist and jaw angles, and computes desired currents for the motors in the IDU 52. The IDU controller 4 Id calculates actual angles based on the motor positions and transmits the actual angles back to the main cart controller 41a.

[0047] The robotic arm 40 is controlled in response to a pose of the handle controller controlling the robotic arm 40, e.g., the handle controller 38a, which is transformed into a desired pose of the robotic arm 40 through a hand eye transform function executed by the controller 21a. The hand eye function, as well as other functions described herein, is / are embodied in software executable by the controller 21a or any other suitable controller described herein. The pose of one of the handle controllers 38a may be embodied as a coordinate position and roll-pitch-yaw (RPY) orientation relative to a coordinate reference frame, which is fixed to the surgeon console 30. The desired pose of the instrument 50 is relative to a fixed frame on the robotic arm 40. The pose of the handle controller 38a is then scaled by a scaling function executed by the controller 21a. In embodiments, the coordinate position may be scaled down and the orientation may be scaled up by the scaling function. In addition, the controller 21a may also execute a clutching function, which disengages the handle controller 38a from the robotic arm 40. In particular, the controller 21a stops transmitting movement commands from the handle controller 38a to the robotic arm 40 if certain movement limits or other thresholds are exceeded and in essence acts like a virtual clutch mechanism, e.g., limits mechanical input from effecting mechanical output.

[0048] The desired pose of the robotic arm 40 is based on the pose of the handle controller 38a and is then passed by an inverse kinematics function executed by the controller 21a. The inverse kinematics function calculates angles for the joints 44a, 44b, 44c of the robotic arm 40 that achieve the scaled and adjusted pose input by the handle controller 38a. The desired angles are then passed to the robotic arm controller 41c, which includes a joint axis controller having a proportional-derivative (PD) controller, the friction estimator module, the gravity compensator module, and a two-sided saturation block, which is configured to limit the commanded torque of the motors of the joints 44a, 44b, 44c. In aspects, handlecontroller 38a may be substituted for and / or employed in conjunction with handle controller 38b. While reference is made above to handle controller 38a, handle controller 38b may also be used in a similar manner.

[0049] With reference to FIG. 5, the surgical robotic system 10 is setup around a surgical table 90. The system 10 includes movable carts 60a-d, which may be numbered “1” through “4.” During setup, each of the carts 60a-d are positioned around the surgical table 90. Position and orientation of the carts 60a-d depends on a plurality of factors, such as placement of a plurality of access ports 55a-d, which in turn, depends on the surgery being performed. Once the port placements are determined, the access ports 55a-d are inserted into the patient, and carts 60a-d are positioned to insert instruments 50 and the endoscopic camera 51 into corresponding ports 55a-d.

[0050] During use, each of the robotic arms 40a-d is attached to one of the access ports 55a- d that is inserted into the patient by attaching the latch 46c (FIG. 2) to the access port 55 (FIG. 3). The IDU 52 is attached to the holder 46, followed by the SIM 43 being attached to a distal portion of the IDU 52. Thereafter, the instrument 50 is attached to the SIM 43. The instrument 50 is then inserted through the access port 55 by moving the IDU 52 along the holder 46.

[0051] With reference to FIG. 6, the IDU 52 is shown in more detail and is configured to transfer power and actuation forces from its motors 152a, 152b, 152c, 152d to the instrument 50 to drive movement of components of the instrument 50, such as articulation, rotation, pitch, yaw, clamping, cutting, etc. The IDU 52 may also be configured for the activation or firing of an electrosurgical energy-based instrument or the like (e.g., cable drives, pulleys, friction wheels, rack and pinion arrangements, etc.).

[0052] The IDU 52 includes a motor pack 150 and a sterile barrier housing 130. Motor pack 150 includes motors 152a, 152b, 152c, 152d for controlling various operations of the instrument 50. The instrument 50 is removably couplable to IDU 52. As the motors 152a, 152b, 152c, 152d of the motor pack 150 are actuated, rotation of the drive transfer shafts 154a, 154b, 154c, 154d of the motors 152a, 152b, 152c, 152d, respectively, is transferred to the drive assemblies of the instrument 50. The instrument 50 is configured to transfer rotational force s / movement supplied by the IDU 52 (e.g., via the motors 152a, 152b, 152c, 152d of the motor pack 150) into longitudinal movement or translation of the cables or drive shafts to effect various functions of an end effector 200 or 200’ (FIGS. 7 and 8). FIG. 7shows a grasper end effector 200 and FIG. 8 shows a shears end effector 200’, for simplicity in describing operation of the IDU 52 reference is made only to the end effector 200. The end effector 200’ operates in substantially similar manner to the grasper end effector 200 of FIGS. 7 and 9 but the jaws 120 and 122 are replaced by blade members 120’ and 122’.

[0053] Each of the motors 152a, 152b, 152c, 152d includes a current sensor 153, a torque sensor 155, and a position sensor 157. For conciseness only operation of the motor 152a is described below, however, it will be understood that motors 152b-d may operate in a similar manner. The sensors 153, 155, 157 monitor the performance ofthe motor 152a. The current sensor 153 is configured to measure the current draw of the motor 152a and the torque sensor 155 is configured to measure motor torque. The torque sensor 155 may be any force or strain sensor including one or more strain gauges configured to convert mechanical forces and / or strain into a sensor signal indicative of the torque output by motor 152a. Position sensor 157 may be any device that provides a sensor signal indicative of the number of rotations of the motor 152a, such as a mechanical encoder or an optical encoder. Parameters which are measured and / or determined by position sensor 157 may include speed, distance, revolutions per minute, position, and the like. The sensor signals from sensors 153, 155, 157 are transmitted to the IDU controller 4 Id, which then controls the motors 152a, 152b, 152c, 152d based on the sensor signals. In particular, the motors 152a, 152b, 152c, 152d are controlled by an actuator controller 159, which controls torque outputted and angular velocity of the motors 152a, 152b, 152c, 152d. In embodiments, additional position sensors may also be used, which include, but are not limited to, potentiometers coupled to movable components and configured to detect travel distances, Hall Effect sensors, accelerometers, and gyroscopes. In embodiments, a single controller can perform the functionality of the IDU controller 41d and the actuator controller 159.

[0054] With reference to FIG. 6, instrument 50 includes an adapter 160 having a housing 162 at a proximal end portion thereof and an elongated shaft 164 that extends distally from housing 162. Housing 162 of instrument 50 is configured to selectively couple to IDU 52, to enable motors 152a, 152b, 152c, 152d of IDU 52 to operate the end effector 200 of the instrument 50. Housing 162 of instrument 50 supports a drive assembly that mechanically and / or electrically cooperates with motors 152a, 152b, 152c, 152d of IDU 52. Drive assembly of instrument 50 may include any suitable electrical and / or mechanical component to effectuate driving force / movement.

[0055] The surgical instrument also includes an end effector 200 coupled to the elongated shaft 164. The end effector 200 may include any number of degrees of freedom allowing the end effector 200 to articulate, pivot, etc., relative to the elongated shaft 164. The end effector 200 may be any suitable surgical end effector configured to treat tissue, such as a dissector, grasper, sealer, stapler, etc.

[0056] As shown in FIGS. 7 and 9, the end effector 200 may include a pair of opposing jaws 120 and 122 that are movable relative to each other. In embodiments, the end effector 200 may include a proximal portion 112 having a first pin 113 and a distal portion 114. Although the jaws 120 and 122 are shown as gripping jaws, it should be understood that the jaws may be any suitable type of jaw, such as shears, etc. The end effector 200 may be actuated using a plurality of cables 201a-d routed through proximal and distal portions 112 and 114 around their respective pulleys 112a, 112b, 114a, 114b, which are integrally formed as arms of the proximal and distal portions 112 and 114. Each of the cables 201a-d is actuated by a respective motor 152a-d via corresponding couplers disposed in adapter 160. In embodiments, the end effector 200, namely, the distal portion 114 and the jaws 120 and 122, may be articulated about the axis “A-A” to control a yaw angle of the end effector with respect to a longitudinal axis “X-X”. The distal portion 114 includes a second pin 115 with a pair of jaws including a first jaw 120 and a second jaw 122 pivotably coupled to the second pin 115. The jaws 120 and 122 are configured to pivot about an axis “B-B” defined by the second pin 115 allowing for controlling a pitch angle of the jaws 120 and 122 as well as opening and closing the jaws 120 and 122. The yaw, pitch, and jaw angles between the jaws 120 and 122 as they are moved between open and closed positions are controlled by adjusting the tension and / or length and direction (e.g., proximal or distal) of the cables 201a- d as shown in FIG. 8. The end effector 200 also includes a cable displacement sensor 116 configured to measure position of the cables 201. Thus, the end effector 200 may have three degrees of freedom, yaw, pitch, and jaw angle between jaws 120 and 122.

[0057] Wristed end effector 200 utilizes for drive cables 20 la-d to articulate pitch, yaw, and jaw degrees of freedom. The cables responsible for closing the jaws are called high-side cables 201b and 201c and those responsible for opening the jaws are called low-side cables 201a and 201d. Thus, the high-side cable 201c and low-side cable 201a actuate the second jaw 122, and high-side cable 201b and the low-side cable 201d actuate the first jaw 120. During closure, the high-side cables 201b and 201c are tensioned while minimum tensionis applied to the low-side cables 201a and 20 Id. During opening, the tension is applied to the cables in reverse, i.e., higher tension to the low-side cables 201a and 20 Id and minimal tension to the high-side cables 201b and 201c. The cables 201a-d are controlled by their respective motors 152a-d. Thus, the motors 152b and 152c are high-side motors as they actuate high-side cables 201b and 201c and the motors 152a and 152d are low-side motors as they actuate low-side cables 201a and 20 Id.

[0058] During actuation of the end effector 200 or the end effector 200’, the IDU controller 41d continuously monitors torque and angular position of each of the motors 152a-d. The IDU controller 4 Id also continuously compares the measured torque of each of the motors 152a-d to a torque threshold as described below.

[0059] With reference to FIG. 10, an illustrative method 400 for detection failure of the instrument 50 and / or detachment of the instrument 50 from the IDU 52 is implemented as software instructions executable by any suitable processor of the robotic system 10, such as the IDU controller 4 Id, the main controller 21a, etc. The method 400 includes monitoring motor torque by receiving torque sensor readings from each torque sensor 155 of each motor 152a-d of the IDU 52. The processor then calculates the average of the four torque sensor readings. When the instrument 50 breaks or is detached from the IDU 52, the average torque drops dramatically, as tension in each of the cables 201a-d drops. The average torque is compared to a threshold indicative of failure or detachment, and if the average torque is below the threshold, then the processor determines that the instrument 50 has failed and / or detached from the IDU 52. In response to this determination, the processor may take one or more remedial actions, such as output an alert to the, write error to a log, automatically control the system to prevent further control of the instrument, automatically control the robotic arm and / or the instrument to extract the instrument, etc.

[0060] The method 400 initially includes recording an average torque value that represents the state of a functional instrument 50 that is properly attached to the IDU 52. At step 402, the torque value may be measured and saved by the IDU 52 during calibration of the instrument 50 and / or when the motors 152a-d are moved to their home, i.e., starting position. Once the instrument 50 is calibrated or homed in, then torque is measured by each torque sensor 155 at each motor 152a-d, received by the processor, and averaged at step 404. The average torque following the calibration or homing procedure is saved as a baseline average torque value at step 406. At step 408, the processor determines the torque threshold bymultiplying the baseline average torque value by a scaling factor to obtain a torque threshold. The scaling factor may be from about 0.25 to about .9, as a scaling factor of 1 would result in detecting any loss in tension as failure, whereas a low scaling factor, e.g., .1, would result in not detecting failure until the cables 201a-d are slackened completely. The torque threshold is then saved in memory.

[0061] In embodiments, instead of an average torque value a total torque value may be used. The total torque value may be calculated by summing all of the measured torque values. The total torque value may be adjusted using a scaling factor as described above to calculate a total torque threshold.

[0062] At step 410, the processor verifies the operational state of the instrument 50 to determine whether the detection of failure is to be performed. Thus, the processor may check whether the instrument 50 is currently being teleoperated, i.e., controlled by user inputs at the surgeon console 40. In embodiments, the processor may also check whether the instrument 50 is extracted or is inserted through the access port 55. In further embodiments, determining whether the detection of failure is to be performed may be done automatically by the ML processing system 310 of FIG. 11. Thus, if the instrument 50 is not being currently teleoperably controlled, or is not inserted through the access port 55, etc., then the determination may be omitted.

[0063] At step 412, after determining the instrument 50 is being operated, the processor periodically receives torque measurement from each torque sensor 155 of each motor 152a- d and is averaged at step 414.

[0064] At step 416, the processor compares the average torque to the torque threshold calculated at step 408. Steps 412-416, i.e., receiving torque measurements, calculating of the average torque, and comparing to the torque threshold, may be performed at any sampling rate suitable for detecting instrument failure, e.g., 1-1,000 Hz, limited by design and / or sensing / processing hardware.

[0065] If the average torque is above the torque threshold, then the tension in the cables 201a-d is sufficient, which denotes that the instrument 50 is operating properly. The processor continues to monitor the torque while the instrument 50 is being teleoperated. If the average torque is below the torque threshold, then the tension in the cables 201a-d is too low, which denotes that the instrument 50 has failed and / or detached from the IDU 52. Accordingly, the processor may undertake any remedial action at step 418, such as issuingan alert and / or stop operation of the instrument 50. The alert may be displayed on any of the display screens 23, 32, 34 of the system 10 such that all of the clinical staff is aware of the error. In addition to the alert, the processor may prevent operation of the of the instrument 10, e.g., receive input but not activate any of the motors 152a-d of the IDU 52 that would actuate the instrument 50. The IDU 52 may be allowed only to perform basic action such as further slacken the cables 201a-d to allow for removal of the instrument 50 through the access port 55. As described above, instead of averaging torque measurements, the measurements may be added to determine the total torque value which is then compared to the total torque threshold.

[0066] With reference to FIG. 11, the surgical robotic system 10 may include an AI / ML processing system 310 that processes the surgical data using one or more ML models to identify one or more features, such as surgical phase, instrument, anatomical structure, etc., in the surgical data. The ML processing system 310 includes a ML training system 325, which may be a separate device (e.g., server) that stores its output as one or more trained ML models 330. The ML models 330 are accessible by a ML execution system 340. The ML execution system 340 may be separate from the ML training system 325, namely, devices that “train” the models are separate from devices that “infer,” i.e., perform real-time processing of surgical data using the trained ML models 330.

[0067] System 10 includes a data reception system 305 that collects surgical data, including the video data and surgical instrumentation data. The data reception system 305 can include one or more devices (e.g., one or more user devices and / or servers) located within and / or associated with a surgical operating room and / or control center. The data reception system 305 can receive surgical data in real-time, i.e., as the surgical procedure is being performed.

[0068] The ML processing system 310, in some examples, may further include a data generator 315 to generate simulated surgical data, such as a set of virtual or masked images, or record the video data from the image processing device 56, to train the ML models 330 as well as other sources of data, e.g., user input, arm movement, etc. Data generator 315 can access (read / write) a data store 320 to record data, including multiple images and / or multiple videos.

[0069] The ML processing system 310 also includes a phase detector 350 that uses the ML models to identify a phase within the surgical procedure. Phase detector 350 uses a particular procedural tracking data structure 355 from a list of procedural tracking datastructures. Phase detector 350 selects the procedural tracking data structure 355 based on the type of surgical procedure that is being performed. In one or more examples, the type of surgical procedure is predetermined or input by user. The procedural tracking data structure 355 identifies a set of potential phases that may correspond to a part of the specific type of surgical procedure.

[0070] In some examples, the procedural tracking data structure 355 may be a graph that includes a set of nodes and a set of edges, with each node corresponding to a potential phase. The edges may provide directional connections between nodes that indicate (via the direction) an expected order during which the phases will be encountered throughout an iteration of the surgical procedure. The procedural tracking data structure 355 may include one or more branching nodes that feed to multiple next nodes and / or may include one or more points of divergence and / or convergence between the nodes. In some instances, a phase indicates a procedural action (e.g., surgical action) that is being performed or has been performed and / or indicates a combination of actions that have been performed. In some instances, a phase relates to a biological state of a patient undergoing a surgical procedure. For example, the biological state may indicate a complication (e.g., blood clots, clogged arteries / veins, etc.), pre-condition (e.g., lesions, polyps, etc.). In some examples, the ML models 330 are trained to detect an “abnormal condition,” such as hemorrhaging, arrhythmias, blood vessel abnormality, etc.

[0071] The phase detector 350 outputs the phase prediction associated with a portion of the video data that is analyzed by the ML processing system 310. The phase prediction is associated with the portion of the video data by identifying a start time and an end time of the portion of the video that is analyzed by the ML execution system 340. The phase prediction that is output may include an identity of a surgical phase as detected by the phase detector 350 based on the output of the ML execution system 340. Further, the phase prediction, in one or more examples, may include identities of the structures (e.g., instrument, anatomy, etc.) that are identified by the ML execution system 340 in the portion of the video that is analyzed. The phase prediction may also include a confidence score of the prediction. Other examples may include various other types of information in the phase prediction that is output. The predicted phase may be used by the controller 21 a to determine when to enable robotic suturing assistance mode as well as other automatic determinations described above.

[0072] 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.

[0073] The following examples are illustrative of the techniques described herein.

[0074] Example 1. A surgical robotic system comprising: an instrument drive unit including a plurality of motors, each of which includes a torque sensor for measuring a torque of a corresponding motor of the plurality of motors; an instrument coupled to the instrument drive unit, the instrument including: an end effector; and a plurality of cables each of which is coupled to and movable by one motor of the plurality of motors to actuate the end effector; and a controller configured to: calculate a torque threshold corresponding to at least one of failure of the instrument or detachment from the instrument drive unit; activate at least one motor of the plurality of motors to actuate the end effector; measure torque of each motor of the plurality of motors during activation of the at least one motor; calculate an average torque value based on measured torque of each motor of the plurality of motors; compare the average torque value to the torque threshold; and output an alert in response to the average torque value being below the torque threshold.

[0075] Example 2. The surgical robotic system according to Example 1, wherein the controller is further configured to calibrate the instrument drive unit with the instrument attached thereto or home each motor of the plurality of motors.

[0076] Example 3. The surgical robotic system according to Example 2, wherein the controller is further configured to measure torque of each motor of the plurality of motors after calibration or homing.

[0077] Example 4. The surgical robotic system according to Example 3, wherein the controller is further configured to calculate a baseline average torque value based on measured torque of each motor of the plurality of motors after calibration or homing.

[0078] Example 5. The surgical robotic system according to Example 4, wherein the controller is further configured to multiply the baseline average torque by a scaling factor to calculate the torque threshold.

[0079] Example 6. The surgical robotic system according to Example 5, wherein the scaling factor is less than one.

[0080] Example 7. The surgical robotic system according to Example 1, further comprising: a surgeon console including a handle controller for receiving input for actuating the end effector and a display screen for displaying the alert.

[0081] Example 8. The surgical robotic system according to Example 7, wherein the controller is further configured to prevent actuation of the end effector by the handle controller in response to the average torque value being below the torque threshold.

[0082] Example 9. A method for detection of instrument failure or detachment from an instrument drive unit, the method comprising: calculating a torque threshold corresponding to at least one of failure of the instrument or detachment from the instrument drive unit, wherein the instrument drive unit includes: a plurality of motors, each of which includes a torque sensor for measuring a torque of a corresponding motor of the plurality of motors; and the instrument is coupled to the instrument drive unit, the instrument includes: an end effector; and a plurality of cables each of which is coupled to and movable by one motor of the plurality of motors to actuate the end effector; and activating at least one motor of the plurality of motors to actuate the end effector; measuring torque of each motor of the plurality of motors during activation of the at least one motor; calculating an average torque value based on measured torque of each motor of the plurality of motors; comparing the average torque value to the torque threshold; and outputting an alert in response to the average torque value being below the torque threshold.

[0083] Example 10. The method according to Example 9, further comprising calibrating the instrument drive unit with the instrument attached thereto or homing each motor of the plurality of motors.

[0084] Example 11. The method according to Example 10, further comprising measuring torque of each motor of the plurality of motors after calibration or homing.

[0085] Example 12. The method according to Example 11, further comprising calculating a baseline average torque value based on measured torque of each motor of the plurality of motors after calibration or homing.

[0086] Example 13. The method according to Example 12, further comprising multiplying the baseline average torque by a scaling factor to calculate the torque threshold.

[0087] Example 14. The method according to Example 13, wherein the scaling factor is less than one.

[0088] Example 15. The method according to Example 9, further comprising: receiving input at a handle controller for actuating the end effector; and displaying the alert on a display screen.

[0089] Example 16. The method according to Example 15, further comprising preventing actuation of the end effector by the handle controller in response to the average torque value being below the torque threshold.

[0090] Example 17. A surgical robotic system comprising: an instrument drive unit including a plurality of motors, each of which includes a torque sensor for measuring a torque of a corresponding motor of the plurality of motors; an instrument coupled to the instrument drive unit, the instrument including: an end effector; and a plurality of cables each of which is coupled to and movable by one motor of the plurality of motors to actuate the end effector; and a controller configured to: calculate a torque threshold corresponding to at least one of failure of the instrument or detachment from the instrument drive unit; activate at least one motor of the plurality of motors to actuate the end effector; determine whether the instrument is being teleoperated, wherein when the instrument is being teleoperated, the controller is further configured to: measure torque of each motor of the plurality of motors during activation of the at least one motor; calculate an average torque value based on measured torque of each motor of the plurality of motors; compare the average torque value to the torque threshold; and output an alert in response to the average torque value being below the torque threshold.

[0091] Example 18. The surgical robotic system according to Example 17, wherein the controller is further configured to calibrate the instrument drive unit with the instrument attached thereto or home each motor of the plurality of motors.

[0092] Example 19. The surgical robotic system according to Example 18, wherein the controller is further configured to measure torque of each motor of the plurality of motors after calibration or homing.

[0093] Example 20. The surgical robotic system according to Example 19, wherein the controller is further configured to: calculate a baseline average torque value based on measured torque of each motor of the plurality of motors after calibration or homing; and multiply the baseline average torque by a scaling factor to calculate the torque threshold.

Claims

WHAT IS CLAIMED IS:

1. A surgical robotic system (10) comprising: an instrument drive unit (52) including a plurality of motors (152a-d), each of which includes a torque sensor (155) for measuring a torque of a corresponding motor of the plurality of motors; an instrument (50) coupled to the instrument drive unit, the instrument including: an end effector (200); and a plurality of cables (201a-d) each of which is coupled to and movable by one motor of the plurality of motors to actuate the end effector; and a controller (21a, 4 Id) configured to: calculate a torque threshold corresponding to at least one of failure of the instrument or detachment from the instrument drive unit; activate at least one motor of the plurality of motors to actuate the end effector; measure torque of each motor of the plurality of motors during activation of the at least one motor; calculate an average torque value based on measured torque of each motor of the plurality of motors; compare the average torque value to the torque threshold; and output an alert in response to the average torque value being below the torque threshold.

2. The surgical robotic system according to claim 1, wherein the controller is further configured to calibrate the instrument drive unit with the instrument attached thereto or home each motor of the plurality of motors.

3. The surgical robotic system according to claim 2, wherein the controller is further configured to measure torque of each motor of the plurality of motors after calibration or homing.

4. The surgical robotic system according to claim 3, wherein the controller is further configured to calculate a baseline average torque value based on measured torque of each motor of the plurality of motors after calibration or homing.

5. The surgical robotic system according to claim 4, wherein the controller is further configured to multiply the baseline average torque by a scaling factor to calculate the torque threshold.

6. The surgical robotic system according to claim 5, wherein the scaling factor is less than one.

7. The surgical robotic system according to any preceding claim, further comprising: a surgeon console (30) including a handle controller (38a, 38b) for receiving input for actuating the end effector and a display screen (32, 34) for displaying the alert.

8. The surgical robotic system according to claim 7, wherein the controller is further configured to prevent actuation of the end effector by the handle controller in response to the average torque value being below the torque threshold.

9. A method for detection of failure or detachment of instrument (50) from an instrument drive unit (52), the method comprising: calculating a torque threshold corresponding to at least one of failure of the instrument or detachment from the instrument drive unit, wherein the instrument drive unit includes: a plurality of motors (152a-d), each of which includes atorque sensor (155) for measuring a torque of a corresponding motor of the plurality of motors; and the instrument is coupled to the instrument drive unit, the instrument includes: an end effector (200); and a plurality of cables (201a-d) each of which is coupled to and movable by one motor of the plurality of motors to actuate the end effector; andactivating at least one motor of the plurality of motors to actuate the end effector; measuring torque of each motor of the plurality of motors during activation of the at least one motor; calculating an average torque value based on measured torque of each motor of the plurality of motors; comparing the average torque value to the torque threshold; and outputting an alert in response to the average torque value being below the torque threshold.

10. The method according to claim 9, further comprising calibrating the instrument drive unit with the instrument attached thereto or homing each motor of the plurality of motors.

11. The method according to claim 10, further comprising measuring torque of each motor of the plurality of motors after calibration or homing.

12. The method according to claim 11, further comprising calculating a baseline average torque value based on measured torque of each motor of the plurality of motors after calibration or homing.

13. The method according to claim 12, further comprising multiplying the baseline average torque by a scaling factor to calculate the torque threshold.14 The method according to claim 13, wherein the scaling factor is less than one.

15. The method according to any preceding claim, further comprising: receiving input at a handle controller (38a, 38b) for actuating the end effector; displaying the alert on a display screen (32, 34); and preventing actuation of the end effector by the handle controller in response to the average torque value being below the torque threshold.

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