WO2025191425A1

WO2025191425A1 - Surgical robotic system for overstroke adjustment based on jaw position

Info

Publication number: WO2025191425A1
Application number: PCT/IB2025/052494
Authority: WO
Inventors: Mohsen Moradi DALVAND
Original assignee: Covidien LP
Current assignee: Covidien LP
Priority date: 2024-03-15
Filing date: 2025-03-07
Publication date: 2025-09-18
Anticipated expiration: 2026-09-15

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 and a position sensor for measuring a position of the 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 having a first jaw and a second jaw, a first cable coupled to the first jaw and actuatable by at least a first motor of the plurality of motors, and a second cable coupled to the second jaw and actuatable by at least a second motor of the plurality of motors, where the first and second cables move the first and second jaws, respectively, between an open position and a closed position. The system further include a controller for: receiving an input including an overstroke command instructing the plurality of motors to apply a force to the first and second jaws; calculating a desired angle between the first jaw and the second jaw based on at least the position of the first motor and the second motor; comparing the desired angle between the first jaw and the second jaw to a first threshold; and adjusting the overstroke command if the desired angle between the first jaw and the second jaw is lower than the first threshold.

Description

SURGICAL ROBOTIC SYSTEM FOR OVERSTROKE ADJUSTMENT BASED ON JAW POSITION

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63/565,607, filed March 15, 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 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.

SUMMARY

[0004] 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 and a position sensor for measuring a position of the 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 having a first jaw and a second jaw, a first cable coupled to the first jaw and actuatable by at least a first motor of the plurality of motors, and a second cable coupled to the second jaw and actuatable by at least a second motor of the plurality of motors, where the first and second cables move the first and second jaws, respectively, between an open position and a closed position. The system further includes a controller for: receiving an input including an overstroke command which instructs the plurality of motors to apply a force to the first and second jaws; calculating a desired angle between the first jaw and the second jaw based on a measured position of each motor of the plurality of motors; comparing the desired angle between the first jaw and the second jaw to a first threshold; and adjusting the overstroke command if the desired angle between the first jaw and the second jaw is lower than the first threshold.

[0005] 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 further calculate a derivative of the desired angle between the first jaw and the second jaw. The controller may further calculate an absolute value of the derivative of the desired angle between the first jaw and the second jaw. The controller may also compare the absolute derivative of the desired angle between the first jaw and the second jaw to a second threshold. The controller may additionally determine whether to adjust the overstroke command if the desired angle between the first jaw and the second jaw is lower than the first threshold and the absolute derivative of the desired angle between the first jaw and the second jaw is lower than the second threshold. The end effector may be a shears and each of the first jaw and the second jaw may include a blade. The controller may also calculate a force for the overstroke command based on the desired angle between the first jaw and the second jaw. The controller may additionally adjust the force for the overstroke command using a scaling factor selected based on the desired angle between the first jaw and the second jaw. The controller may further detect an overtorque condition based on a measured torque of any motor of the plurality of motors exceeding a torque threshold.

[0006] According to another embodiment of the present disclosure, a surgical robotic system is disclosed. The surgical robotic system 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 a position sensor for measuring a position of the corresponding motor of the plurality of motors. The system also includes an instrument having a shears end effector with a first blade and a second blade, a first cable coupled to the first blade and actuatable by a first motor of the plurality of motors, and a second cable coupled to the second blade and actuatable by at least a second motor of the plurality of motors, where the first and second cables move the first and second blades from an open position to a closed position, respectively. The system further includes a controller for: receiving an input including an overstroke command which instructs the plurality of motors to apply a force to the first and second blades; calculating a desired angle between the first blade and the second blade based on a measured position of each motor of the plurality of motors; comparing the desired angle between the first blade and the second blade to a first threshold; and adjusting the overstroke command if the desired angle between the first blade and the second blade is lower than the first threshold.

[0007] 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 further calculate a derivative of the desired angle between the first blade and the second blade. The controller may further calculate an absolute value of the derivative of the desired angle between the first blade and the second blade. The controller may also compare the absolute derivative of the desired angle between the first blade and the second blade to a second threshold. The controller may additionally determine whether to adjust the overstroke command if the desired angle between the first blade and the second blade is lower than the first threshold and the absolute derivative of the desired angle between the first blade and the second blade is lower than the second threshold. The controller may also calculate a force for the overstroke command based on the desired angle between the first blade and the second blade. The controller may also adjust the force for the overstroke command using a scaling factor selected based on the desired angle between the first blade and the second blade . The controller may further detect an overtorque condition based on a measured torque of any motor of the plurality of motors exceeding a torque threshold.

[0008] According to a further embodiment of the present disclosure, a method for controlling a surgical robotic instrument is disclosed. The method includes moving a first jaw and a second jaw from an open position to a closed position, where the first jaw is coupled to a first cable actuatable by a first motor and the second jaw is coupled to a second cable actuatable by a second motor. The method also includes measuring an angular position of the first motor and the second motor. The method further includes receiving an input including an overstroke command which instructs the first and second motors to apply a force to the first and second jaws and calculating a desired angle between the first jaw and the second jaw based on at least the measured angular position of the first motor and the second motor. The method additionally includes comparing desired angle between the first jaw and the second jaw to a first threshold and adjusting the overstroke command if the desired angle between the first jaw and the second jaw is lower than the first threshold.

[0009] 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 calculating a derivative of the desired angle between the first jaw and the second jaw, and calculating an absolute value of the derivative of the desired angle between the first jaw and the second jaw. The method may further include comparing the absolute derivative of the desired angle between the first jaw and the second jaw to a second threshold and determining whether to adjust the overstroke command if the desired angle between the first jaw and the second jaw is lower than the first threshold and the absolute derivative of the desired angle between the first jaw and the second jaw is lower than the second threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Various embodiments of the present disclosure are described herein with reference to the drawings wherein:

[0011] 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;

[0012] 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;

[0013] 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;

[0014] 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;

[0015] 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;

[0016] 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;

[0017] 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 ; [0018] 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 ;

[0019] FIG. 9 shows the end effector in various configurations according to an embodiment of the present disclosure; and

[0020] FIG. 10 is a flow chart of a method for overstroke adjustment based on jaw position according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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, it will be understood that various types of surgical instruments for use during minimally invasive surgical procedures are contemplated and within the scope of this disclosure.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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 50 or 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.

[0029] 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)).

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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. [0036] 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).

[0037] 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. [0038] 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.

[0039] 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.

[0040] 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.

[0041] 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 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.

[0042] 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.

[0043] 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.

[0044] 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, handle controller 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.

[0045] 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.

[0046] 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.

[0047] 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.).

[0048] 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. 7 shows 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’.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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 tension is 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.

[0054] 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 indicative of overtorque, which may be about 0.65 Nm. If the overtorque condition is detected, then the IDU controller 4 Id may stop operation of all of the motors 152a-d to avoid damaging the instrument 50 and/or tissue. In certain cases, such overtorque protection may generate false positives.

[0055] The present disclosure provides for a system and method to detect and avoid overtorque, which may occur when the blade members 120’ and 122’ are partially closed, i.e., not fully, then paused, and then commanded to fully close, i.e., 0° closure angle. In particular, overtorque is detected after moving the blade members 120’ and 122’ to a fully closed position in response to an overstroke command. Overstroke function is used to command the blade members 120’ and 122’ to ensure the tissue or object is fully cut, rather than merely closing the blade members 120’ and 122’ to a fully closed position. Thus, the overstroke command includes outputting excessive torque by the motors 152a-d not to merely close the blade members 120’ and 122’ but to close them with excess force to cut the object.

[0056] The reason for overtorque detection is that the overstroke generated for some of the small actuation events is as large as that of full closing events. In a full closing event, there is enough time for the overstroke to be consumed by the blade friction of the blade members 120’and 122’. However, in small actuation events where the blade members are mostly closed, there is not enough time for the fully generated overstroke force to be consumed. Therefore, the remaining part of the overstroke force is applied to the cables when the jaws are fully closed. This results in excessive tension in the cables 201a-d and, consequently, measured as excessive torque sensor readings. The method for operating the overstroke command in such situations is to scale down the overstroke force for small or partial closing events by using a scaling function.

[0057] The scaling function is applied to both small and partial closing events. The small closing events start from zero angle where the blade members 120’ and 122’ are completely closed and continue opening to a small angle and then return to zero angle. The partial closing events are those that start from 100% opening where the blade members 120’ and 122’ are fully open and continue closing to a small angle (e.g., less than 10°), and then after a pause, continue closing to zero angle. The scaling algorithm detects a pause or change in direction and initiates scaling down of the overstroke function. Thus, the overstroke function is tailored to aperture (i.e., jaw angle) of the blade members 120’ and 122’.

[0058] With reference to FIG. 10, a illustrative method for adjusting the overstroke function in a bladed end effector 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 is executed in response to an overstroke command, which may be executed by the IDU controller 4 Id in response to a full close or cut input provided by the user to cut the object (e.g., tissue, suture, etc.) via the handle controller 38a or 38b.

[0059] Motor position and torque for each motor 152a-d are provided to the controller 41d. In particular, the torque sensor 155 provides torque measurements and the position sensor 157 provides angular rotational position of each of the motors 152a-d. The angular position is then used by the controller 4 Id to determine position of the cables 201a-d and the end effector 200. The torque is used to determine whether an overtorque condition has occurred. The IDU controller 41d compares the measured torque of each of the motors 152a-d to a torque threshold indicative of overtorque. The overtorque comparisons may be done periodically, at a present rate of about 10 Hz, compares which may be about 0.65 Nm.

[0060] At step 400, the jaw position, e.g., a desired angle between the blade members 120’ and 122’, is calculated based on the angular position data provided by the position sensors 157 of the motors 152a-d. The desired jaw angle corresponds to angle being input by the user. [0061] At step 402, the jaw position is compared to a first threshold (i.e., jaw position threshold). The IDU controller 41d outputs a true value if the jaw position is smaller than the first threshold. The desired jaw angle is also processed by taking a derivative thereof at step 404. An absolute value of the derivative of the jaw position is calculated at step 406. The resulting absolute value of the derivative of the jaw position is then compared to a second threshold (i.e., threshold absolute derivative of the jaw position) at step 408. The IDU controller 4 Id outputs a true value if the processed jaw position value is smaller than the second threshold, otherwise the controller 4 Id outputs a false value.

[0062] At step 410, the controller receives as inputs the outputs from the jaw position determinations of steps 406 and 408 and performs an AND operation on the inputs. Thus, if the output of step 410 is no, i.e., one or both of the values of steps 406 and 408 is false, which denotes that the blade members 120’ and 122’ are open beyond a low aperture, the method still proceeds to step 412. If both values are true, i.e., the jaw position is below the first and second thresholds, which denotes that the blade members 120’ and 122’ are open at or less than the low aperture, then the method proceeds to step 414.

[0063] At step 412, the IDU controller 4 Id calculates the overstroke command to use the full overstroke force, which may be stored as a value in memory. At step 414, the IDU controller 41d adjusts the overstroke command. The IDU controller 41d calculates a modified overstroke force that is used when the blade members 120’ and 122’ are open to the low aperture. The overstroke force is calculated using a scaling factor, which may include multiplying the full overstroke force by the scaling factor. The scaling factor corresponds to the aperture of the blade members 120’ and 122’ and is then used to adjust the overstroke force accordingly. The scaling factor may be stored in memory (e.g., a lookup table) and looked up by the IDU controller 4 Id based on the aperture of the blade members 120’ and 122’or calculated by the IDU controller 4 Id using a transfer function based on the aperture of the blade members 120’ and 122’.

[0064] At step 416, the overstroke command, either the full force command from step 412 or adjusted force command from step 414, is executed by the IDU controller 4 Id. The motors 152a-d are commanded to actuate the blade members 120’ and 122’ into the overstroke movement based on the force of the overstroke. Thereafter, the method returns to step 400 to continue monitoring for overtorque and corresponding overstroke force. While the method of FIG. 10 was described with respect to a bladed end effector, the overstroke command may be used in a variety of other jawed end effectors, such as a grasper end effector 200 of FIGS. 7 and 9, suturing end effectors, vessel sealers, and the like. In such situations the overstroke command may be used to impart excess torque by the motors 152a-d to apply additional pressure to the object, e.g., tissue, being grasped by the end effector.

[0065] 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.

[0066] The following examples are illustrative of the techniques described herein.

[0067] 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 and a position sensor for measuring a position of the corresponding motor of the plurality of motors; an instrument coupled to the instrument drive unit, the instrument including: an end effector having a first jaw and a second jaw; a first cable coupled to the first jaw and actuatable by at least a first motor of the plurality of motors; and a second cable coupled to the second jaw and actuatable by at least a second motor of the plurality of motors, wherein the first and second cables move the first and second jaws, respectively, between an open position and a closed position; and a controller configured to: receive an input including an overstroke command instructing the plurality of motors to apply a force to the first and second jaws; calculate a desired angle between the first jaw and the second jaw based on a measured position of each motor of the plurality of motors; compare the desired angle between the first jaw and the second jaw to a first threshold; and adjust the overstroke command if the desired angle between the first jaw and the second jaw is lower than the first threshold.

[0068] Example 2. The surgical robotic system according to Example 1, wherein the controller is further configured to calculate a derivative of the desired angle between the first jaw and the second jaw.

[0069] Example 3. The surgical robotic system according to Example 2, wherein the controller is further configured to calculate an absolute value of the derivative of the desired angle between the first jaw and the second jaw. [0070] Example 4. The surgical robotic system according to Example 3, wherein the controller is further configured to compare the absolute value of the derivative of the desired angle between the first jaw and the second jaw to a second threshold.

[0071] Example 5. The surgical robotic system according to Example 4, wherein the controller is further configured to determine whether to adjust the overstroke command if the desired angle between the first jaw and the second jaw is lower than the first threshold and the absolute value of the derivative of the desired angle between the first jaw and the second jaw is lower than the second threshold.

[0072] Example 6. The surgical robotic system according to Example 1, wherein the end effector is a shears and each of the first jaw and the second jaw includes a blade.

[0073] Example 7. The surgical robotic system according to Example 1, wherein the controller is further configured to calculate a force for the overstroke command based on the desired angle between the first jaw and the second jaw.

[0074] Example 8. The surgical robotic system according to Example 7, wherein the controller is further configured to adjust the force for the overstroke command using a scaling factor selected based on the desired angle between the first jaw and the second jaw. [0075] Example 9. The surgical robotic system according to Example 1, wherein the controller is further configured to detect an overtorque condition based on a measured torque of any motor of the plurality of motors exceeding a torque threshold.

[0076] Example 10. A surgical robotic system comprising: 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 a position sensor for measuring a position of the corresponding motor of the plurality of motors; an instrument including: a shears end effector having a first blade and a second blade; a first cable coupled to the first blade and actuatable by a first motor of the plurality of motors; and a second cable coupled to the second blade and actuatable by at least a second motor of the plurality of motors, wherein the first and second cables move the first and second blades from an open position to a closed position, respectively; and a controller configured to: receive an input including an overstroke command instructing the plurality of motors to apply a force to the first and second blades; calculate a desired angle between the first blade and the second blade based on a measured position of each motor of the plurality of motors; compare the desired angle between the first blade and the second blade to a first threshold; and adjust the overstroke command if the desired angle between the first blade and the second blade is lower than the first threshold.

[0077] Example 11. The surgical robotic system according to Example 10, wherein the controller is further configured to calculate a derivative of the desired angle between the first blade and the second blade.

[0078] Example 12. The surgical robotic system according to Example 11, wherein the controller is further configured to calculate an absolute value of the derivative of the desired angle between the first blade and the second blade.

[0079] Example 13. The surgical robotic system according to Example 12, wherein the controller is further configured to compare the absolute value of the derivative of the desired angle between the first blade and the second blade to a second threshold.

[0080] Example 14. The surgical robotic system according to Example 13, wherein the controller is further configured to determine whether to adjust the overstroke command if the desired angle between the first blade and the second blade is lower than the first threshold and the absolute value of the derivative of the desired angle between the first blade and the second blade is lower than the second threshold.

[0081] Example 15. The surgical robotic system according to Example 10, wherein the controller is further configured to calculate a force for the overstroke command based on the desired angle between the first blade and the second blade.

[0082] Example 16. The surgical robotic system according to Example 15, wherein the controller is further configured to adjust the force for the overstroke command using a scaling factor selected based on the desired angle between the first blade and the second blade.

[0083] Example 17. The surgical robotic system according to Example 10, wherein the controller is further configured to detect an overtorque condition based on a measured torque of any motor of the plurality of motors exceeding a torque threshold.

[0084] Example 18. A method for controlling a surgical robotic instrument, the method comprising: moving a first jaw and a second jaw from an open position to a closed position, wherein the first jaw is coupled to a first cable actuatable by a first motor and the second jaw is coupled to a second cable actuatable by a second motor; measuring an angular position of the first motor and an angular position of the second motor; receiving an input including an overstroke command instructing the first and second motors to apply a force to the first and second jaws; calculating a desired angle between the first jaw and the second jaw based on at least the measured angular position of the first motor and the measured angular position of the second motor; comparing the desired angle between the first jaw and the second jaw to a first threshold; and adjusting the overstroke command if the desired angle between the first jaw and the second jaw is lower than the first threshold.

[0085] Example 19. The method according to Example 18, further comprising: calculating a derivative of the desired angle between the first jaw and the second jaw; and calculating an absolute value of the derivative of the desired angle between the first jaw and the second jaw.

[0086] Example 20. The method according to Example 19, further comprising: comparing the absolute value of the derivative of the desired angle between the first jaw and the second jaw to a second threshold; and determining whether to adjust the overstroke command if the desired angle between the first jaw and the second jaw is lower than the first threshold and the absolute value of the derivative of the desired angle between the first jaw and the second jaw is lower than the second 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 and a position sensor (157) for measuring a position of the corresponding motor of the plurality of motors; an instrument (50) coupled to the instrument drive unit, the instrument including: an end effector (200) having a first jaw (120, 120’) and a second jaw (122, 122’); a first cable (201a, 20 Id) coupled to the first jaw and actuatable by at least a first motor of the plurality of motors; and a second cable (201b, 201c) coupled to the second jaw and actuatable by at least a second motor of the plurality of motors, wherein the first and second cables move the first and second jaws, respectively, between an open position and a closed position; and a controller (21a, 4 Id) configured to: receive an input including an overstroke command instructing the plurality of motors to apply a force to the first and second jaws; calculate a desired angle between the first jaw and the second jaw based on a measured position of each motor of the plurality of motors; compare the desired angle between the first jaw and the second jaw to a first threshold; and adjust the overstroke command if the desired angle between the first jaw and the second jaw is lower than the first threshold.

2. The surgical robotic system according to claim 1, wherein the controller is further configured to calculate a derivative of the desired angle between the first jaw and the second jaw.

3. The surgical robotic system according to claim 2, wherein the controller is further configured to calculate an absolute value of the derivative of the desired angle between the first jaw and the second jaw.

4. The surgical robotic system according to claim 3, wherein the controller is further configured to compare the absolute value of the derivative of the desired angle between the first jaw and the second jaw to a second threshold.

5. The surgical robotic system according to claim 4, wherein the controller is further configured to determine whether to adjust the overstroke command if the desired angle between the first jaw and the second jaw is lower than the first threshold and the absolute value of the derivative of the desired angle between the first jaw and the second jaw is lower than the second threshold.

6. The surgical robotic system according to any preceding claim, wherein the end effector is a shears (200’) and each of the first jaw and the second jaw includes a blade.

7. The surgical robotic system according to any preceding claim, wherein the controller is further configured to calculate a force for the overstroke command based on the desired angle between the first jaw and the second jaw.

8. The surgical robotic system according to claim 7, wherein the controller is further configured to adjust the force for the overstroke command using a scaling factor selected based on the desired angle between the first jaw and the second jaw.

9. The surgical robotic system according to any preceding claim, wherein the controller is further configured to detect an overtorque condition based on a measured torque of any motor of the plurality of motors exceeding a torque threshold.

10. A method for controlling a surgical robotic instrument (50), the method comprising: moving a first jaw (120) and a second jaw (122) from an open position to a closed position, wherein the first jaw is coupled to a first cable (201a, 20 Id) actuatable by a first motor (152a) and the second jaw is coupled to a second cable (201b, 201c) actuatable by a second motor (152b); measuring an angular position of the first motor and an angular position of the second motor; receiving an input including an overstroke command instructing the first and second motors to apply a force to the first and second jaws; calculating a desired angle between the first jaw and the second jaw based on at least the measured angular position of the first motor and the measured angular position of the second motor; comparing the desired angle between the first jaw and the second jaw to a first threshold; and adjusting the overstroke command if the desired angle between the first jaw and the second jaw is lower than the first threshold.

11. The method according to claim 10, further comprising: calculating a derivative of the desired angle between the first jaw and the second jaw; and calculating an absolute value of the derivative of the desired angle between the first jaw and the second jaw.

12. The method according to claim 11, further comprising: comparing the absolute value of the derivative of the desired angle between the first jaw and the second jaw to a second threshold; and determining whether to adjust the overstroke command if the desired angle between the first j aw and the second j aw is lower than the first threshold and the absolute value of the derivative of the desired angle between the first jaw and the second jaw is lower than the second threshold.