Surgical robotic system and method for instrument slack procedure in response to cable breakage

Abstract

A surgical robotic system includes an instrument drive unit including a plurality of motors each having a torque sensor and a position sensor. The system also includes an instrument coupled to the instrument drive unit. The instrument includes an end effector and a plurality of cables each of which is actuated by a corresponding motor of the plurality of motors to actuate the end effector. The system further includes a non-transient computer readable medium containing program instructions executable by a processor for causing the instrument drive unit to perform a method of determining whether at least one cable is broken based on sensor data provided by at least one of the torque sensor or the position sensor, and controlling the plurality of motors to reduce tension in the plurality of cables.

Description

SURGICAL ROBOTIC SYSTEM AND METHOD FOR INSTRUMENT SLACK PROCEDURE IN RESPONSE TO CABLE BREAKAGECROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 587,778, filed October 4, 2023, 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 are actuated by one or more cables, which may snap during use due to high strain placed on them during actuation. Cable snapping results in uncontrolled movement of portions of the instruments, e.g., end effector, which may damage other instruments or camera.SUMMARY

[0004] According to one embodiment of the present disclosure, a surgical robotic system is disclosed. The surgical robotic system includes an instrument drive unit including a plurality of motors each having a torque sensor and a position sensor. The system also includes an instrument coupled to the instrument drive unit. The instrument includes an end effector and a plurality of cables each of which is actuated by a corresponding motor of the plurality of motors to actuate the end effector. The system further includes a non-transient computer readable medium containing program instructions executable by a processor for causing the instrument drive unit to perform a method of determining whether at least one cable is broken based on sensor data provided by at least one of the torque sensor or the position sensor, and controlling the plurality of motors to reduce tension in the plurality of cables.

[0005] 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 further includeoutputting an alert indicating that at least one cable is broken. The instrument may also include a plurality of rotatable input couplers each of which engages a corresponding motor of the plurality of motors. Each rotatable input coupler of the plurality of rotatable input couplers may include a drive screw. The instrument further includes a plurality of drive nuts threadably coupled to a corresponding drive screw. Each drive nut is coupled to a corresponding cable of the plurality of cables. Controlling the plurality of motors includes activating only at least one motor coupled to an unbroken cable. The method may further include determining whether the plurality of motors reduced the tension in the plurality of cables based on sensor data provided by the torque sensor. The method may further include determining whether the plurality of motors reduced the tension in the plurality of cables based on sensor data provided by the motor position sensor.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Various embodiments of the present disclosure are described herein with reference to the drawings wherein:

[0007] 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;

[0008] 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;

[0009] 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;

[0010] 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;

[0011] 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;

[0012] 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;

[0013] FIG. 7 is a side, cross-sectional view of the instrument according to an embodiment of the present disclosure, for use in the surgical robotic system of FIG. 1;

[0014] FIG. 8 is a top, perspective view of the end effector of FIG. 7, according to an embodiment of the present disclosure;

[0015] FIG. 9 shows the end effector in various configurations according to an embodiment of the present disclosure; and

[0016] FIG. 10 is a flow chart of a method for slacking the instrument in response to cable breakage according to an embodiment of the present disclosure.DETAILED DESCRIPTION

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The surgeon console 30 includes a first screen 32, which displays a video feed of the surgical site provided by camera 51 disposed on the robotic arm 40, and a second screen 34, which displays a user interface for controlling the surgical robotic system 10. The first screen 32 and second screen 34 may be touchscreens allowing for displaying various graphical user inputs.

[0023] 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.

[0024] The control tower 20 includes a screen 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.

[0025] 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 otherusing 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)).

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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 tocouple 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).

[0033] 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.

[0034] 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.

[0035] 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 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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 functionexecuted 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.).

[0044] 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).

[0045] Each of the motors 152a-d 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. 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 41d, 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.

[0046] With reference to FIGS. 6 and 7, 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 170 that mechanically and / or electrically cooperates with motors 152a-d of IDU 52. Drive assembly 170 of instrument 50 includes a plurality of rotatable input couplers 172, each of which is actuated by the corresponding motors 152a-d. The couplers 172 are threaded and include onecorresponding drive nut 174 threadably coupled a corresponding drive screw 173. The drive nuts 174 are prevented from rotational movement by the housing of the drive assembly 170. The drive nuts 174 move longitudinally along the couplers 172 as the couplers 172 are rotated by the motors 152a-d and are maintained in the longitudinal position via tension springs 175. Each of the drive nuts 174 is coupled to a corresponding cable 201a-d via a drive rod 176 and a crimp 178. Thus, as drive nuts 174a-d are moved longitudinally, the cables 201a-d are also moved longitudinally, thereby tensioning the cables 201a-d.

[0047] 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.

[0048] 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. In embodiments, the end effector 200 may include a proximal portion 112 having a first pin 113 and a distal portion 114. The end effector 200 is actuated using the plurality of cables 20 la-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 20 la-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.

[0049] During certain movements of the end effector 200, such as closing of the jaws 120 and 122, ifhigh enough tension is applied to the cables 201a-d some ofthe cables 201a-d may snap. With particular reference to the present design and routing of the cables 20 la-d, high-sidecables 201b, 201c may snap during high tension events. Following the snap, there is uncommanded movement of the end effector 200, e .g . , snapping to one side, due to high tension in the intact high side cable 201b or 201c which continues to actuate the corresponding motor 152b or 152c until the commanded position is reached. The present disclosure provides a system and a method configured, using sensor signals from the motors 152a-d, to predict and / or detect when any of the cables 201a-d, and in particular high side cables 201b and 201c will snap.

[0050] With reference to FIG. 9, a method for predicting or detecting cable snaps is implemented as software instructions executable by any suitable processor of the robotic system 10, such as the IDU controller 41d, the main controller 21a, etc. At step 300, motor position and torque for each motor 152a-d are provided to the controller 4 Id. 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.

[0051] At step 302, measured torque and cable position are used to detect and / or predict cable breakage. Cable breakage may be detected by comparing the measured torque or motor position and / or derivatives (e.g., rates of change) of these values to corresponding thresholds that are indicative of the cable breakage.

[0052] Once cable breakage occurs, the end effector 200 is driven to an approximate rightangle position relative to the elongated shaft 164 due to tension applied by other (i.e., unsnapped) cables, which are still tensioned. Thus, it may be difficult or impossible to remove the instrument 50 through the access port 55. If the access port 55 is removed while the instrument 50 is fully articulated, the abdominal wall may be damaged during the removal process.

[0053] At step 304, once cable breakage is detected, the controller 21a disables further user input commands from controlling the instrument 50 and outputs a prompt on one of the GUIs of the screens 23, 32, 34. The prompt may be an alert indicating that a cable snap has occurred so that the user stops attempting to control the instrument 50.

[0054] Following the prompt, at step 306, the system enters an instrument exchange process during which the instrument 50 is withdrawn from the access port 55. During the instrument exchange process and prior to withdrawal of the instrument 50, all of the motors 152a-d are driven so that all of the input couplers 172 are driven to remove tension in the cables 201a-d, or at least the input couplers 172 of the cables 201a-d that are not broken are driven in thismanner. Thus, the IDU controller 41d determines which cable 201a-d is broken and corresponding motor 152a-d to only control the motor(s) coupled to unbroken cables.

[0055] The IDU 52 may verify that sufficient slack has been achieved based on torque or position. The couplers 172a-d may be driven until the measured torque is minimal or approximately 0 with the drive nuts 174a-d being driven distally to remove tension. Conversely, the couplers 172a-d may be driven to a desired position with the drive nuts 174a- d being driven distally to remove tension. Once the remaining cables 201a-d are slackened, the end effector 200 may be passively manipulated, e.g., such as when the instrument 50 is being withdrawn and contacts a cannula portion of the access port 55. The contact with the cannula bends the end effector 200 into a relatively straight configuration allowing for withdrawal of the instrument 50 through the access port 55.

[0056] 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.

Claims

WHAT IS CLAIMED IS:

1. A surgical robotic system comprising: an instrument drive unit including a plurality of motors each having a torque sensor and a position sensor; an instrument coupled to the instrument drive unit, the instrument including an end effector and a plurality of cables each of which is actuated by a corresponding motor of the plurality of motors to actuate the end effector; and a non-transient computer readable medium containing program instructions executable by a processor for causing the instrument drive unit to perform a method of: determining whether at least one cable is broken based on sensor data provided by at least one of the torque sensor or the position sensor; and controlling the plurality of motors to reduce tension in the plurality of cables.

2. The surgical robotic system according to claim 1, wherein the method further includes outputting an alert indicating that at least one cable is broken.

3. The surgical robotic system according to claim 1, wherein the instrument further includes a plurality of rotatable input couplers each of which engages a corresponding motor of the plurality of motors.

4. The surgical robotic system according to claim 3, wherein each rotatable input coupler of the plurality of rotatable input couplers includes a drive screw.

5. The surgical robotic system according to claim 4, wherein the instrument further includes a plurality of drive nuts threadably coupled to a corresponding drive screw.

6. The surgical robotic system according to claim 5, wherein each drive nut is coupled to a corresponding cable of the plurality of cables.

7. The surgical robotic system according to claim 1, wherein controlling the plurality of motors includes activating only at least one motor coupled to an unbroken cable.

8. The surgical robotic system according to claim 1, wherein the method further includes determining whether the plurality of motors reduced the tension in the plurality of cables based on sensor data provided by the torque sensor.

9. The surgical robotic system according to claim 1, wherein the method further includes determining whether the plurality of motors reduced the tension in the plurality of cables based on sensor data provided by the position sensor.

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