WO2025057104A2

WO2025057104A2 - Surgical robotic system and method for control of wristed instruments

Info

Publication number: WO2025057104A2
Application number: PCT/IB2024/058885
Authority: WO
Inventors: Peter A. York; Brian A. Rockrohr
Original assignee: Covidien LP
Current assignee: Covidien LP
Priority date: 2023-09-15
Filing date: 2024-09-12
Publication date: 2025-03-20
Anticipated expiration: 2026-03-15
Also published as: WO2025057104A3

Abstract

A surgical robotic system including a processor for receiving the position input and determining sufficient torque to be applied by the first and second jaw members for grasping. The processor includes a jaw torque estimator module for receiving the plurality of parameters of each motor of the plurality of motors and calculating an estimated joint torque for the first and second jaw members based on the plurality of parameters of each motor of the plurality of motors. The processor also includes a clamping controller module for calculating clamping angular position for each motor of the plurality of motors controlling clamping of the first and second jaw members based on the estimated joint torque for the first and second jaw members. The processor further includes a motor position controller module for calculating desired angular position for each motor of the plurality of motors based on the clamping angular position and the position input and controlling the plurality of motors based on the desired angular position to clamp at the sufficient torque

Description

SURGICAL ROBOTIC SYSTEM AND METHOD FOR CONTROL OF WRISTED INSTRUMENTS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of, and priority to, U.S. Provisional Patent Application Serial No. 63/582,877 filed on September 15, 2023. The entire contents of the foregoing application is incorporated by reference herein.

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] Some surgical robotic instruments include cable-driven wristed instruments, which may be classified as closed- or open-chain manipulators. In closed-chain manipulators, each output degree of freedom is coupled to a single actuation input. In open-chain manipulators, coordination between the actuation inputs is used to achieve bi-directional motion of each output degree of freedom. In both types of manipulators, cables are tensioned to maintain the relationship between inputs and outputs of the instrument. Otherwise, actuation inputs will not generate output motion and controllability will be diminished. The tension in closed-chain manipulators is generally set during assembly - the cable is stretched around the drive pulleys and held in place by crimps. In contrast, the tension in open-chain manipulators is set during use, as part of a control scheme.

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 is moved by a corresponding motor via a threaded coupler. The wristed instrument is an open-chain 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] According to one embodiment of the present disclosure, a surgical robotic system is disclosed. The system includes a robotic arm having an instrument drive unit, which includes a plurality of motors and a plurality of sensors, each of which measures a plurality of parameters of each motor of the plurality of motors. The robotic arm also includes an instrument coupled to the instrument drive unit and actuatable by the plurality of motors. The instrument includes an end effector having a first grasping jaw member and a grasping second jaw member. One of the first or second jaw members is movable relative to the other of the first or second jaw members from an open jaw position to a closed jaw position. The system also includes a surgeon console having a handle controller receiving a position input to control position of the end effector and an opening angle between the first and second jaw members. The system further includes a processor for receiving the position input and determining sufficient torque to be applied by the first and second jaw members for grasping. The processor includes a jaw torque estimator module for receiving the plurality of parameters of each motor of the plurality of motors and calculating an estimated joint torque for the first and second jaw members based on the plurality of parameters of each motor of the plurality of motors. The processor also includes a clamping controller module for calculating clamping angular position for each motor of the plurality of motors controlling clamping of the first and second jaw members based on the estimated joint torque for the first and second jaw members. The processor further includes a motor position controller module for calculating desired angular position for each motor of the plurality of motors based on the clamping angular position and the position input and controlling the plurality of motors based on the desired angular position to clamp at the sufficient torque.

[0007] Implementations of the above embodiment may include one or more of the following features. According to one aspect of the above embodiment, the position input may include a desired angle for the end effector and the first and second jaw members. The processor may also include an inverse kinematics module for calculating the desired angular position based on the desired angle for the end effector and the first and second jaw members. The position input may include desired torque for the first and second jaw members. The clamping controller module may calculate the desired angular position based on the desired torque and the estimated joint torque. The plurality of sensors may include a motor torque sensor and an angular motor position sensor. The jaw torque estimator may calculate the estimated joint torque for the first and second jaw members based on a sensed motor torque from the motor torque sensor and a sensed angular position from the angular motor position sensor. The motor position controller module may calculate the desired angular position based on the clamping angular position, the position input, and the sensed angular position.

[0008] According to another embodiment of the present disclosure, a surgical robotic system is disclosed. The system includes a robotic arm having an instrument drive unit, which includes a plurality of motors and a plurality of sensors, each of which measures a plurality of parameters of each motor of the plurality of motors. The system also includes an instrument coupled to the instrument drive unit and actuatable by the plurality of motors. The instrument includes a shears end effector having a first bladed jaw member and a second bladed jaw member. One of the first or second jaw members is movable relative to the other of the first or second jaw members from an open jaw position to a closed jaw position. The system also includes a surgeon console having a handle controller receiving a position input to control position of the end effector and an opening angle between the first and second jaw members. The system further includes a processor for receiving the position input and determining sufficient torque to be applied by the first and second jaw members for cutting. The processor includes a jaw position estimator module for receiving the plurality of parameters of each motor of the plurality of motors and calculating an estimated joint position for the first and second jaw members based on the plurality of parameters of each motor of the plurality of motors. The processor also includes a cutting controller module for calculating cutting angular position for each motor of the plurality of motors controlling cutting of the first and second jaw members based on the estimated joint position for the first and second jaw members. The processor further includes a motor position controller module for calculating desired angular position for each motor of the plurality of motors based on the cutting angular position and the position input and controlling the plurality of motors based on the desired angular position to cut at the sufficient torque.

[0009] Implementations of the above embodiment may include one or more of the following features. According to one aspect of the above embodiment, the position input may include a desired angle for the end effector and the first and second jaw members. The processor may also include an inverse kinematics module for calculating the desired angular position based on the desired angle for the end effector and the first and second jaw members. The position input may further include desired torque for the first and second jaw members. The cutting controller module may calculate the desired angular position based on the desired torque and the estimated joint position. The plurality of sensors may include a motor torque sensor and an angular motor position sensor. The jaw position estimator may also calculate the estimated joint position for the first and second jaw members based on a sensed motor torque from the motor torque sensor and a sensed angular position from the angular motor position sensor. The motor position controller module may also calculate the desired angular position based on the cutting angular position, the position input, and the sensed angular position. The instrument may include a plurality of cables each of which is actuated by one motor of the plurality of motors. The jaw position estimator may calculate stretch value of plurality of cables using a model of transmission stiffness and the sensed motor torque from the motor torque sensor.

[0010] According to one embodiment of the present disclosure, a method for controlling a surgical robotic instrument is disclosed. The method includes receiving a position input at a surgeon console, which includes a handle controller for controlling an instrument, which includes an end effector having first grasping jaw member and a grasping second jaw member. One of the first or second jaw members is movable relative to the other of the first or second jaw members from an open jaw position to a closed jaw position. The method also includes measuring a plurality of parameters at a plurality of sensors of a plurality of motors actuating the end effector and the first and second jaw members. The method further includes calculating an estimated joint torque for the first and second jaw members based on the plurality of parameters of each motor of the plurality of motors. The method additionally includes calculating clamping angular position for each motor of the plurality of motors controlling clamping of the first and second jaw members based on the estimated joint torque for the first and second jaw members. The method further includes calculating desired angular position for each motor of the plurality of motors based on the clamping angular position and the position input. The method additionally includes controlling the plurality of motors based on the desired angular position to clamp the first and second jaws at a sufficient torque.

[0011] Implementations of the above embodiment may include one or more of the following features. According to one aspect of the above embodiment, receiving the position input may include receiving a desired angle for the end effector and the first and second jaw members. The method may also include calculating the desired angular position based on the desired angle for the end effector and the first and second jaw members.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Various embodiments of the present disclosure are described herein with reference to the drawings wherein:

[0013] 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;

[0014] 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;

[0015] 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;

[0016] 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;

[0017] 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;

[0018] 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;

[0019] FIG. 7 is a top, perspective view of an end effector, according to an embodiment of the present disclosure, for use in the surgical robotic system of FIG. 1;

[0020] FIG. 8 shows the end effector in various configurations according to an embodiment of the present disclosure;

[0021] FIG. 9 shows a flow chart of a method for position control of the wristed end effector in motor coordinate space according to an embodiment of the present disclosure;

[0022] FIG. 10 shows a flow chart of a method for position control of the wristed end effector in wrist coordinate space according to an embodiment of the present disclosure; [0023] FIG. 11 shows a flow chart of a method for position control of the wristed grasper in wrist coordinate space with torque feedback estimator according to an embodiment of the present disclosure;

[0024] FIG. 12 shows a shears instrument according to an embodiment of the present disclosure;

[0025] FIG. 13 shows a flow chart of a method for position control of the wristed shears in wrist coordinate space with position feedback estimator according to an embodiment of the present disclosure; and

[0026] FIG. 14 shows a flow chart of the jaw position estimator.

DETAILED DESCRIPTION

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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 apply a surgical clip onto tissue.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] The control tower 20 includes a display 23, which may be a touchscreen, and outputs on 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 hand 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 hand controllers 38a and 38b. Clutching is initiated by pressing one of the foot pedals 36, which disconnects (i.e., prevents movement inputs) the hand controllers 38a and/or 38b from the robotic arm 40 and corresponding instrument 50 or camera 51 attached thereto. This allows the user to reposition the hand 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.

[0035] 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)).

[0036] 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, non-volatile, 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 for by using any logic processor (e.g., control circuit) adapted to execute algorithms, calculations, and/or set of instructions described herein.

[0037] 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. Other configurations 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.

[0038] 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. [0039] 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.

[0040] The actuator 48b of the joint 44b is coupled to the joint 44c via the belt 45 a, 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.

[0041] 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.

[0042] 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 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).

[0043] 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.

[0044] 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 button 53. [0045] 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 2 la and safety observer 21b. 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 of the 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 21b 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.

[0046] 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 41d. 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.

[0047] 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 41b monitors slippage of each of joints 63a and 63b and the rotatable base 64 of the 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 arm 40. 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.

[0048] 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.

[0049] 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 2 la 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.

[0050] 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 calculated 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.

[0051] 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.

[0052] 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.

[0053] 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-d 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.).

[0054] The IDU 52 includes a motor pack 150 and a sterile barrier housing 130. Motor pack 150 includes motors 152a-d for controlling various operations of the instrument 50. The instrument 50 is removably couplable to IDU 52. As the motors 152a-d of the motor pack 150 are actuated, rotation of the drive transfer shafts 154a, 154b, 154c, 154d of the motors 152a-d, respectively, is transferred to the drive assemblies of the instrument 50. The instrument 50 is configured to transfer rotational forces/movement supplied by the IDU 52 (e.g., via the motors 152a-d 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 (FIG. 7).

[0055] Each of the motors 152a-d includes a current sensor 153, a torque sensor 155, and a position sensor 157, which may be an angular motor position sensor. For conciseness only operation of the motor 152a is described below. The sensors 153, 155, 157 monitor the performance of the 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-d based on the sensor signals. In particular, the motors 152a-d are controlled by an actuator controller 159, which controls torque outputted and angular velocity of the motors 152a-d. 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 4 Id and the actuator controller 159.

[0056] 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 of robotic, to enable motors 152a-d 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-d of IDU 52. Drive assembly of instrument 50 may include any suitable electrical and/or mechanical component to effectuate driving force/movement.

[0057] 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.

[0058] As shown in FIGS. 7 and 8, the end effector 200 may include a pair of opposing jaws 120 and 122 that are movable relative to each other. The jaws 120 and 122 may be grippers as shown or any other suitable type of jaws, e.g., shears, sealers, etc. In embodiments, the end effector 200 may include a proximal portion 112 having a first pin 113 and a distal portion 114 (i.e., wrist portion). 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 j aw 122 pivotably coupled to the second pin 115. The j aws 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 may also include 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. Control algorithms for a cable actuated instrument 50 are also described in International Patent Application No. PCT/US2022/019703, “Surgical Robotic System for Realignment of Wristed Instruments,” filed on March 10, 2022, the entire disclosure of which is incorporated by reference herein. [0059] The instrument 50 is an open-chain wristed instrument. The input/output relationship for the open-chain wristed instrument 50 according to the present disclosure is provided by an inverse kinematics relationship, which relates the wrist motion to the rotation of the motors 152a-d represented by formula (I):

[0060] In formula (I), 9 is the motor position, A is the pitch of the drive screw, r_y is the radius of the yaw pulley, ry is the radius of the pitch/jaw pulley, and 0 is the wrist pose (yaw, pitch, jaw).

[0061] FIG. 9 shows a control algorithm based on the input/output relationship between the motors and the wrist motion, which converts the desired wrist pose into desired motor positions and close the loop on motor position using encoder feedback. The control algorithm may be implemented as software instructions executed by one of the controllers of the system 10 and provides for position control of the end effector 200 in motor coordinates.

[0062] With reference to FIG. 9, the desired angle(s) of the wrist pose and/or jaw angle are provided to an inverse kinematics module 300, which then outputs a desired angular position (i.e., number of rotations) for each of the motors 152a-d. The desired angular position is compared to the actual angular position of the corresponding motors 152a-d as determined by measured position of each of the motors 152a-d by their respective position sensors 157 to determine an error angular position, i.e., a difference between the actual angular position to achieve the desired angular positions. Each motor controller 302 of each of the motors 152a- d, receives the corresponding error angular position and generates a desired torque command, which is then used by the corresponding motor 152a-d to achieve the desired position of the motors 152a-d.

[0063] FIG. 10 shows another control algorithm for controlling the position of the end effector 200 and the jaws 120 and 122, which is based in coordinates of the end effector 200 rather than the coordinates of the motors 152a-d as the method of FIG. 9. The method of FIG. 10 may be implemented as software instructions executed by one of the controllers of the system 10. The control algorithm of FIG. 10 acts on desired wrist angles directly, with a separate controller provided for each of the three wrist degrees of freedom. [0064] With reference to FIG. 10, the desired angle(s) of the wrist pose are compared to estimated angle(s) as provided by forward kinematics module 400 to determine an error angle, i.e., a difference between the actual angle to achieve the desired angle. The forward kinematics module 400 relates motor positions to end effector positions using formula (II).

[0065] In formula (II), 9 is the motor position, A is the pitch of the drive screw, r_y is the radius of the yaw pulley, ry is the radius of the pitch/jaw pulley, and 0 is the wrist pose (yaw, pitch, jaw). The differences in wrist pose angles are provided to individual (i.e., three) wrist pose controller modules 401, each of which then generates a desired torque in wrist coordinates. An inverse statics module 402 converts the desired torque to motor coordinates via the inverse statics mapping using formula (III).

[0066] In formula (III), T are motor torques, 77 is drive screw efficiency, T are wrist torques, r_y is the radius of the yaw pulley, ry is the radius of the pitch/jaw pulley. The desired torque command is then used by the motors 152a-d to achieve the desired position of the end effector 200 and/or the jaws 120 and 122.

[0067] The control scheme of FIG. 10 does not enforce the maintenance of cable tension by adjusting or varying the torque of the motors 152a-d. Instead, the control scheme of FIG. 10 adds a constant torque value to the desired torque from the position controller to keep tension in the cables. This control scheme is particularly suitable since it is implemented with respect to the coordinates directly connected to user perception and system requirements (e.g., wrist tracking accuracy). However, this control scheme also requires high cable tension due to the use of the additional constant torque. This could be surmounted to some degree by using a secondary control scheme that monitors the tension in the cables and injects additional torque when low tension is sensed. While technically feasible, this may place the position controller in conflict with the secondary control scheme, such that the former pushes cable tension down while the latter pulls the tension up. This is especially problematic because the main control scheme requests equal motor torque to pull and release the cables, so as cable tension decreases, the secondary controller must become more and more reactive in order to hold tension in the cables 201a-d. In contrast, the control scheme of FIG. 9, i.e., position controller in motor coordinates, provides an alternative pathway for maintaining tension in the cables, especially as the cable tension decreases. Implementing the position controller in motor coordinates also provides a foundation that is easily extendable for layering additional functionality, which allows for inclusion of additional control schemes such as those described further below.

[0068] FIG. 11 shows a flow chart of a method for position control of the wristed grasping end effector of FIGS. 7 and 8 in wrist coordinate space with torque feedback estimator. Regulation of jaw torque during grasping is a useful control parameter. In particular, sufficient clamping torque is needed for manipulation while too much torque can lead to tissue damage. Moreover, objects of a range of sizes need to be grasped and held with consistent clamping torque. The method of FIG. 11 is similar to the method of FIG. 10 and includes an outer control loop having a jaw torque estimator module, which estimates the jaw torque based on the motor torque and motor position provided by the torque sensor 155 and the position sensor 157, respectively. The outer control loop engages when the user closes the input device, i.e., the handle controller 38a or 38b, and commands additional motor displacement based on the difference between the desired and estimated clamp torque. The outer loop could also be commanded to engage whenever a jaw torque of sufficient magnitude is sensed.

[0069] The method of FIG. 11 may be implemented as software instructions executed by one of the controllers of the system 10. The desired input angle(s) of the wrist pose and/or jaw angle are provided to an inverse kinematics module 500 from the input provided through the handle controllers 38a and 38b, e.g., by moving or clamping input paddles, etc. The inverse kinematics module 500 then outputs a desired angular position (i.e., number of rotations) for each of the motors 152a-d. The desired angular position is combined with desired clamping angular position of the corresponding motors 152a-d, which is provided by a clamping controller 502, to output a combined desired angular position.

[0070] The desired angular position is provided to a motor position controller 501, which includes an input shaping filter 504 for processing the combined desired angular position to eliminate vibration and/or resonance. The filtered angular position is compared to the actual angular position as determined by measured position of each of the motors 152a-d by their respective position sensors 157 to determine an error angular position i.e., a difference between the actual angular position to achieve the desired angular position. Each motor controller 506 of each of the motors 152a-d, receives the corresponding error angular position and generates a desired torque command, which is then used by the corresponding motor 152a-d to achieve the desired position of the motors 152a-d. [0071] The control scheme of FIG. 11 also includes an additional outer control loop, which includes the clamping controller 502 and a jaw torque estimator 508. The motor torque and motor position are provided by the torque sensor 155 and the position sensor 157, respectively, to the jaw torque estimator 508, which calculates estimated joint torques for the jaws 120 and 122. The estimated torque is provided to the clamping controller 502, which also receives a desired joint torque from the user input through the handle controllers 38a and 38b, e.g., based on speed of the user input. The clamping controller 502 compares the desired torque values to the estimated torque values and calculates an error torque value, i.e., a difference between the desired and estimated torque values. The error torque and the desired input angular position, which was also provided to the inverse kinematics module 500, are used to calculate the desired clamping angular position for the motors 152a-d as described above.

[0072] The additional functionality provided by an additional outer control loop may be implemented in controlling other instruments including a shears end effector 200’, which is shown in FIG. 12. The end effector 200’ operates in substantially similar manner to the grasper instrument of FIGS. 7 and 8 but the jaws 120 and 122 are replaced by bladed jaws 120’ and 122’ . For the end effector 200’, the additional functionality provided by the outer control loop is enhanced position tracking for the jaw degree of freedom. During cutting, the interference between the jaws 120’ and 122’ and resistance from objects being cut causes the cables 201a- d to stretch and the tracking of the jaw position to be inaccurate. By compensating for that stretch, jaw position tracking may be significantly improved. This enhancement to the basic control scheme is shown in a flow chart of FIG. 13. A jaw position estimator estimates the physical jaw angle based on the motor position and estimated stretch in the cables 201a-d, as calculated from the motor torque sensor 155. The outer control loop engages when the user closes the handle controller 38a or 38b to provide additional motor displacement to work through the cable stretch and fully close the jaws 120’ and 122’ .

[0073] FIG. 13 shows a flow chart of a method for position control of the wristed shears end effector of FIG. 12 in wrist coordinate space with position feedback estimator. The method of FIG. 13 is similar to the method of FIGS. 10 and 11 and includes an outer control loop having a jaw position estimator module, which estimates the jaw position based on the motor torque and motor position provided by the torque sensor 155 and the position sensor 157, respectively. Jaw position as used herein includes the opening angle between the jaws 120’ and 122’. The outer control loop engages when the user closes the input device, i.e., the handle controller 38a or 38b, and commands additional motor displacement based on the difference between the desired and estimated shearing torque. [0074] The method of FIG. 13 may be implemented as software instructions executed by one of the controllers of the system 10. The desired input angle(s) of the wrist pose and/or jaw angle are provided to an inverse kinematics module 600 from the input provided through the handle controllers 38a and 38b, e.g., by moving or clamping input paddles, etc. The inverse kinematics module 600 then outputs a desired angular position (i.e., number of rotations) for each of the motors 152a-d. The desired angular position is combined with desired clamping angular position of the corresponding motors 152a-d, which is provided by a cutting controller 602, to output a combined desired angular position.

[0075] The desired angular position is provided to a motor position controller 601, which includes an input shaping filter 604 for processing the combined desired angular position to eliminate vibration and/or resonance. The filtered angular position is compared to the actual angular position as determined by measured position of each of the motors 152a-d by their respective position sensors 157 to determine an error angular position i.e., a difference between the actual angular position to achieve the desired angular position. Each motor controller 606 of each of the motors 152a-d, receives the corresponding error angular position and generates a desired torque command, which is then used by the corresponding motor 152a-d to achieve the desired position of the motors 152a-d.

[0076] The control scheme of FIG. 13 also includes an additional outer control loop, which includes the cutting controller 602 and a jaw position estimator 608. With reference to FIG. 14, which shows a more detailed flow chart of the jaw position estimator 608. The motor torque and motor position are provided by the torque sensor 155 and the position sensor 157, respectively, to the jaw position estimator 608, which calculates estimated angles (i.e., position) for wrist pose of the end effector 200’ and/or jaw angle the jaws 120’ and 122’. The jaw position estimator 608 includes a model of transmission stiffness to calculate the amount of stretch in the system (i.e., cables 201a-d) and to deduct that amount from the encoder angles before calculating the jaw angle from the kinematics. The stretch is calculated based on the motor torque measured by the torque sensors 155.

[0077] The estimated jaw position is provided to the cutting controller 602, which also receives a desired jaw position from the user input through the handle controllers 38a and 38b, e.g., based on orientation and angles of the handle controllers 38a and 38b. The cutting controller 602 compares the desired position to the estimated position and calculates an error jaw position, i.e., a difference between the desired and estimated jaw positions. The error jaw position and the desired input angle, which was also provided to the inverse kinematics module 600, are used to calculate the desired clamping angle of the jaws 120’ and 122’ as described above.

[0078] 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.

[0079] The following examples are illustrative of the techniques described herein.

[0080] Example 1. A surgical robotic system comprising: a robotic arm including: an instrument drive unit including a plurality of motors and a plurality of sensors, each of which measures a plurality of parameters of each motor of the plurality of motors; and an instrument coupled to the instrument drive unit and actuatable by the plurality of motors, the instrument including an end effector having a first jaw member and a second jaw member, at least one of the first or second jaw members movable relative to the other of the first or second jaw members from an open jaw position to a closed jaw position; a surgeon console including a handle controller receiving a position input to control position of the end effector and an opening angle between the first and second jaw members; and a processor for: receiving the position input and determining sufficient torque to be applied by the first and second jaw members for grasping; receiving the plurality of parameters of each motor of the plurality of motors and calculating an estimated joint torque for the first and second jaw members based on the plurality of parameters of each motor of the plurality of motors; calculating clamping angular position for each motor of the plurality of motors controlling clamping of the first and second jaw members based on the estimated joint torque for the first and second jaw members; and calculating desired angular position for each motor of the plurality of motors based on the clamping angular position and the position input and controlling the plurality of motors based on the desired angular position to clamp at the sufficient torque.

[0081] Example 2. The surgical robotic system according to Example 1, wherein the position input includes a desired angle for the end effector and the first and second jaw members.

[0082] Example 3. The surgical robotic system according to Example 2, wherein the processor further calculates the desired angular position based on the desired angle for the end effector and the first and second jaw members.

[0083] Example 4. The surgical robotic system according to Example 1, wherein the position input includes desired torque for the first and second jaw members. [0084] Example 5. The surgical robotic system according to Example 4, wherein the processor further calculates the desired angular position based on the desired torque and the estimated joint torque.

[0085] Example 6. The surgical robotic system according to Example 1, wherein the plurality of sensors includes a motor torque sensor and an angular motor position sensor.

[0086] Example 7. The surgical robotic system according to Example 6, wherein the processor further calculates the estimated joint torque for the first and second jaw members based on a sensed motor torque from the motor torque sensor and a sensed angular position from the angular motor position sensor.

[0087] Example 8. The surgical robotic system according to Example 7, wherein the processor further calculates the desired angular position based on the clamping angular position, the position input, and the sensed angular position.

[0088] Example 9. A surgical robotic system comprising: a robotic arm including: an instrument drive unit including a plurality of motors and a plurality of sensors, each of which measures a plurality of parameters of each motor of the plurality of motors; and an instrument coupled to the instrument drive unit and actuatable by the plurality of motors, the instrument including a shears end effector having a first bladed jaw member and a second bladed jaw member, at least one of the first or second jaw members movable relative to the other of the first or second jaw members from an open jaw position to a closed jaw position; a surgeon console including a handle controller receiving a position input to control position of the end effector and an opening angle between the first and second jaw members; and a processor for: receiving the position input and determining sufficient torque to be applied by the first and second jaw members for cutting; receiving the plurality of parameters of each motor of the plurality of motors and calculating an estimated joint position for the first and second jaw members based on the plurality of parameters of each motor of the plurality of motors; calculating cutting angular position for each motor of the plurality of motors controlling cutting of the first and second jaw members based on the estimated joint position for the first and second jaw members; and calculating desired angular position for each motor of the plurality of motors based on the cutting angular position and the position input and controlling the plurality of motors based on the desired angular position to cut at the sufficient torque.

[0089] Example 10. The surgical robotic system according to Example 9, wherein the position input includes a desired angle for the end effector and the first and second jaw members. [0090] Example 11. The surgical robotic system according to Example 10, wherein the processor further calculates the desired angular position based on the desired angle for the end effector and the first and second jaw members.

[0091] Example 12. The surgical robotic system according to Example 9, wherein the position input includes desired torque for the first and second jaw members.

[0092] Example 13. The surgical robotic system according to Example 12, wherein the processor further calculates the desired angular position based on the desired torque and the estimated joint position.

[0093] Example 14. The surgical robotic system according to Example 9, wherein the plurality of sensors includes a motor torque sensor and an angular motor position sensor.

[0094] Example 15. The surgical robotic system according to Example 14, wherein the processor further calculates the estimated joint position for the first and second jaw members based on a sensed motor torque from the motor torque sensor and a sensed angular position from the angular motor position sensor.

[0095] Example 16. The surgical robotic system according to Example 15, wherein the processor further calculates the desired angular position based on the cutting angular position, the position input, and the sensed angular position.

[0096] Example 17. The surgical robotic system according to Example 14, wherein the instrument includes a plurality of cables each of which is actuated by one motor of the plurality of motors.

[0097] Example 18. The surgical robotic system according to Example 17, wherein the processor further calculates a stretch value of plurality of cables using a model of transmission stiffness and the sensed motor torque from the motor torque sensor.

[0098] Example 19. A method for controlling a surgical robotic instrument, the method comprising: receiving a position input at a surgeon console including a handle controller to control an instrument including an end effector having first grasping jaw member and a grasping second jaw member, at least one of the first or second jaw members movable relative to the other of the first or second jaw members from an open jaw position to a closed jaw position; measuring a plurality of parameters at a plurality of sensors of a plurality of motors actuating the end effector and the first and second jaw members; calculating an estimated joint torque for the first and second jaw members based on the plurality of parameters of each motor of the plurality of motors; calculating clamping angular position for each motor of the plurality of motors controlling clamping of the first and second jaw members based on the estimated joint torque forthe first and second jaw members; calculating desired angular position for each motor of the plurality of motors based on the clamping angular position and the position input; and controlling the plurality of motors based on the desired angular position to clamp the first and second jaws at a sufficient torque.

[0099] Example 20. The method according to Example 19, wherein receiving the position input includes receiving a desired angle for the end effector and the first and second jaw members and the method further includes calculating the desired angular position based on the desired angle for the end effector and the first and second jaw members.

Claims

WHAT IS CLAIMED IS:

1. A surgical robotic system (10) comprising: a robotic arm (40) including: an instrument drive unit (52) including a plurality of motors (152a-d) and a plurality of sensors (153, 155, 157), each of which measures a plurality of parameters of each motor of the plurality of motors; and an instrument (50) coupled to the instrument drive unit and actuatable by the plurality of motors, the instrument including an end effector (200, 200’) having a first jaw member (120, 120’) and a second jaw member (122, 122’), at least one of the first or second jaw members movable relative to the other of the first or second jaw members from an open jaw position to a closed jaw position; a surgeon console (30) including a handle controller (38a, 38b) receiving a position input to control position of the end effector and an opening angle between the first and second jaw members; and a processor (21a, 41a) for: receiving the position input and determining sufficient torque to be applied by the first and second jaw members for grasping; receiving the plurality of parameters of each motor of the plurality of motors and calculating an estimated joint torque for the first and second jaw members based on the plurality of parameters of each motor of the plurality of motors; calculating clamping angular position for each motor of the plurality of motors controlling clamping of the first and second jaw members based on the estimated joint torque for the first and second jaw members; and calculating desired angular position for each motor of the plurality of motors based on the clamping angular position and the position input and controlling the plurality of motors based on the desired angular position to clamp at the sufficient torque.

2. The surgical robotic system according to claim 1, wherein the position input includes a desired angle for the end effector and the first and second jaw members.

3. The surgical robotic system according to claim 2, wherein the processor further calculates the desired angular position based on the desired angle for the end effector and the first and second jaw members.

4. The surgical robotic system according to any preceding claim, wherein the position input includes desired torque for the first and second jaw members.

5. The surgical robotic system according to claim 4, wherein the processor further calculates the desired angular position based on the desired torque and the estimated joint torque.

6. The surgical robotic system according to any preceding claim, wherein the plurality of sensors includes a motor torque sensor and an angular motor position sensor.

7. The surgical robotic system according to claim 6, wherein the processor further calculates the estimated joint torque for the first and second jaw members based on a sensed motor torque from the motor torque sensor and a sensed angular position from the angular motor position sensor.

8. The surgical robotic system according to claim 7, wherein the processor further calculates the desired angular position based on the clamping angular position, the position input, and the sensed angular position.

9. A surgical robotic system (10) comprising: a robotic arm (40) including: an instrument drive unit (52) including a plurality of motors (152a-d) and a plurality of sensors (153, 155, 157), each of which measures a plurality of parameters of each motor of the plurality of motors; and an instrument (50) coupled to the instrument drive unit and actuatable by the plurality of motors, the instrument including a shears end effector (200) having a first bladed jaw member (120’) and a second bladed jaw member (122’), at least one of the first or second jaw members movable relative to the other of the first or second jaw members from an open jaw position to a closed jaw position; a surgeon console (30) including a handle controller (38a, 38b) receiving a position input to control position of the end effector and an opening angle between the first and second jaw members; and a processor (21a, 41a) for: receiving the position input and determining sufficient torque to be applied by the first and second jaw members for cutting; receiving the plurality of parameters of each motor of the plurality of motors and calculating an estimated joint position for the first and second jaw members based on the plurality of parameters of each motor of the plurality of motors; calculating cutting angular position for each motor of the plurality of motors controlling cutting of the first and second jaw members based on the estimated joint position for the first and second jaw members; and calculating desired angular position for each motor of the plurality of motors based on the cutting angular position and the position input and controlling the plurality of motors based on the desired angular position to cut at the sufficient torque.

10. The surgical robotic system according to claim 9, wherein the position input includes a desired angle for the end effector and the first and second jaw members.

11. The surgical robotic system according to claim 10, wherein the processor further calculates the desired angular position based on the desired angle for the end effector and the first and second jaw members.

12. The surgical robotic system according to any of claims 9-11, wherein the position input includes desired torque for the first and second jaw members.

13. The surgical robotic system according to claim 12, wherein the processor further calculates the desired angular position based on the desired torque and the estimated joint position.

14. The surgical robotic system according to any of claims 9-13, wherein the plurality of sensors includes a motor torque sensor and an angular motor position sensor.

15. The surgical robotic system according to claim 14, wherein the processor further calculates the estimated joint position for the first and second jaw members based on a sensed motor torque from the motor torque sensor and a sensed angular position from the angular motor position sensor.

16. The surgical robotic system according to claim 15, wherein the processor further calculates the desired angular position based on the cutting angular position, the position input, and the sensed angular position.

17. The surgical robotic system according to claim 14, wherein the instrument includes a plurality of cables each of which is actuated by one motor of the plurality of motors.

18. The surgical robotic system according to claim 17, wherein the processor further calculates a stretch value of plurality of cables using a model of transmission stiffness and the sensed motor torque from the motor torque sensor.