limit the clamp force and maintain a minimum opening force of the jaws in the position control mode and control the clamp force when transitioning between the position control mode and the force mode

Abstract

Systems and methods for limiting the clamp force generated by a robotic wrist jaw operating in a position mode in which the jaw is commanded to a desired jaw angle before the jaw is commanded to generate a clamp force are disclosed. Systems and methods for maintaining the opening force generated by a robotic wrist jaw operating in a position mode in which the jaw is commanded to a desired jaw angle before the jaw is commanded to generate a clamp force are also disclosed. Systems and methods for achieving a smooth transition in clamp force when a wrist jaw transitions between a position mode and a force mode are also disclosed.

Description

Technical Field

[0001] This technology relates generally to robots and surgical systems, and more specifically to controlling the clamping or opening force of surgical tools, such as the wrist jaws of robot-assisted surgical systems. Background Technology

[0002] Minimally invasive surgical procedures (MIS), such as laparoscopic surgery, utilize techniques designed to minimize tissue damage during surgical procedures. Laparoscopic procedures typically require multiple small incisions inside the patient (e.g., in the abdomen) through which several surgical instruments (such as endoscopes, scalpels, graspers, and needles) are inserted. Inflation of the abdomen with gas provides more space around the tips of the instruments, making it easier for the surgeon to see (via the endoscope) and manipulate tissue at the surgical site. MIS can also be performed using robotic systems, where surgical instruments are operatively attached to the distal end of a robotic arm, and the system controls the actuator arm and its attached instruments so that, while a user input device (UID) is being manipulated by the surgeon in their hands, the arm and its attached instruments mimic the movement of that UID and tool-specific commands.

[0003] Surgical tools may include a robotic wrist supporting a pair of opposing jaws. The wrist and jaws can move in multiple degrees of freedom when controlled by commands from a remote operator to perform grasping, cutting, suturing, and other surgical tasks. For example, actuators in the tool drive of the robotic arm can drive multi-axis movements (e.g., pitch and yaw) of the wrist jaws to pivot, open, close the jaws, or control the clamping or opening force between the jaws while moving the wrist to any angular position. The jaws can grasp patient tissue, hold cutting instruments, etc. Precise control of the clamping or opening force when closing or opening the jaws is crucial to preventing damage to tissue or ensuring accurate instrument cutting. Furthermore, the jaws can operate in a position mode and a force mode, in which the angle between the pair of jaws is commanded to be the desired jaw angle, and in a force mode, the jaws are commanded to apply the desired clamping force. The smooth transition between position and force modes minimizes undesirable abrupt changes in clamping force that could lead to the accidental drop of any object being grasped. Summary of the Invention

[0004] A system and method are disclosed for limiting the gripping force generated by closing the jaws of a robot wrist while operating in a position control mode, wherein the jaws are commanded to reach a desired jaw angle before being commanded to generate a gripping force. In position control mode, or simply position mode, the desired jaw angle is above a threshold corresponding to the angle at which both jaws simultaneously contact an object between them, or, if no object is to be gripped, the angle at which the jaws begin to touch each other. When the desired jaw angle is below the threshold, the wrist jaws operate in force control mode, or simply force mode, and the desired jaw angle is converted into a desired gripping force. The disclosed system and method limit the maximum amount of gripping force when the jaws are closed in position mode to prevent damage to tissue that can be gripped by the jaws. The gripping force can be estimated or measured. A feedback loop can analyze the desired jaw angle and the measured gripping force to determine whether the jaws are closed in position mode and whether the measured gripping force exceeds a pre-specified maximum gripping force threshold. If so, the feedback loop can calculate the clamping force error to limit the measured clamping force to a pre-specified maximum clamping force threshold.

[0005] In another aspect, a system and method are disclosed for achieving a minimum jaw opening force by means of wrist jaws operating in a position mode. Maintaining a minimum jaw opening force when the jaws are open in a position mode helps the jaws overcome resistance that may prevent the jaws from opening to a desired jaw angle. The opening force, representing the jaw opening force and jaw angle, can be measured or estimated. A feedback loop can analyze the desired jaw angle, the estimated jaw angle, and the measured jaw opening force to determine whether the jaws are open in a position mode and whether the measured jaw opening force is below a pre-specified minimum opening force threshold. If so, the feedback loop can calculate a jaw opening force error to maintain the jaw opening force above the pre-specified minimum opening force threshold.

[0006] In another aspect, a system and method are disclosed for achieving a smooth transition of gripping force when the wrist jaws change between a position mode and a force mode. The smooth transition from position mode to force mode and from force mode to position mode minimizes undesirable abrupt changes in gripping force that could cause the wrist jaws to accidentally drop the grasped object when the jaws cross a discontinuity between the two modes. In one embodiment, to transition from position mode to force mode, a stabilization strategy can be used to ensure that the desired jaw angle is less than a pre-specified minimum duration of the threshold between the position and force modes before the wrist jaws transition to force mode.

[0007] In one implementation, the system and method can determine a desired clamping force based on a desired jaw angle and can measure or estimate the clamping force. A feedback loop can analyze the desired jaw angle, the desired clamping force, and the measured clamping force to determine whether the jaws are transitioning from a position mode to a force mode, whether the error between the measured clamping force and the desired clamping force exceeds a pre-specified maximum force error, and whether the desired clamping force is increasing. If so, when the jaws transition from a position mode to a force mode, the feedback loop can set the desired clamping force to the currently measured clamping force minus a pre-specified margin.

[0008] In one implementation, the feedback loop analyzes the desired jaw angle, the desired clamping force determined based on the desired jaw angle, and the measured clamping force to determine whether the jaws are transitioning from a force mode to a position mode, whether the desired clamping force is less than the minimum clamping force value, whether the desired clamping force is decreasing, and whether the absolute value of the error between the measured clamping force and the minimum clamping force is less than a pre-specified maximum force error. If so, the feedback loop can set the desired clamping force to the minimum clamping force value when the jaws transition from a force mode to a position mode.

[0009] A method for controlling the jaw clamping force generated by the jaws of a clamping tool is disclosed. The method may include determining whether the jaws are closed in a position mode based on a desired jaw angle between the jaws. The position mode is characterized by applying a position command to drive the jaws to a desired position with the desired jaw angle. The method further includes determining whether, if the jaws are closed in the position mode, the measured clamping force exceeds a maximum clamping force threshold. The method also includes generating a clamping force error to be combined with the position command to limit the measured clamping force to the maximum clamping force threshold if the measured clamping force exceeds the maximum clamping force threshold.

[0010] Another method for controlling the jaw opening force generated by the jaws of a clamping tool is disclosed. The method may include determining whether the jaws are in a position mode based on a desired jaw angle between the jaws. The position mode is characterized by applying a position command to drive the jaws to a desired position with the desired jaw angle. The method further includes, if the jaws are in a position mode, determining whether a jaw angle error between the desired jaw angle and a measured jaw angle is greater than an error threshold. The method further includes, if the jaw angle error is greater than the error threshold, determining whether a measured opening force is less than a minimum opening force threshold. The method further includes, if the measured opening force is less than the minimum opening force threshold, generating an opening force error to be combined with a position command to maintain the measured opening force above the minimum opening force threshold.

[0011] Another method for controlling the clamping force generated by the jaws of a clamping tool is disclosed. The method may include determining whether the jaws are transitioning between a position mode and a force mode based on a change in a desired jaw angle between the jaws. During the position mode, the jaws are driven at a commanded jaw angle, which may be the desired jaw angle. During the force mode, the jaws are driven with a commanded clamping force determined based on the desired jaw angle having a negative value. The method further includes determining whether to adjust the commanded clamping force during the transition between the position mode and the force mode based on the commanded clamping force and a measured clamping force. If so, the method further includes adjusting the commanded clamping force to reduce the change in the measured clamping force; otherwise, the measured clamping force is determined based on the desired jaw angle during the transition. Attached Figure Description

[0012] To provide a more complete understanding of the invention, the accompanying drawings are provided together with the following description of various aspects and embodiments of the subject matter. The drawings and embodiments are illustrative of the invention and are not intended to limit its scope. It should be understood that those skilled in the art can modify the drawings to generate drawings of other embodiments that will still fall within the scope of the invention.

[0013] Figure 1 This is a drawing view of an exemplary surgical robot system 1 in the operating room, based on various aspects of the subject matter.

[0014] Figure 2 This is a schematic diagram illustrating an exemplary design of a robotic arm, tool drive, and cannula loaded with robotic surgical tools according to various aspects of the subject matter.

[0015] Figure 3A and Figure 3B This is a schematic diagram illustrating exemplary tool drive devices with and without loaded tools according to various aspects of the subject matter.

[0016] Figure 4A and Figure 4B The present invention illustrates an exemplary gripper end effector according to various aspects of the subject matter, the end effector having a robotic wrist, a pair of opposing jaws, and a pulley and cable system for connecting the robotic wrist and the pair of jaws to an actuator of a tool drive.

[0017] Figure 5 This is a block diagram of an exemplary control system for controlling the position and clamping force of an end effector of a robotic surgical tool, based on various aspects of the subject matter.

[0018] Figure 6AIt is a time curve showing the commanded jaw angle, measured jaw angle, commanded clamping force, and measured clamping force of the wrist jaw when the jaws are closed in position mode and the measured clamping force is unrestricted.

[0019] Figure 6B This is a time graph showing the commanded jaw angle, measured jaw angle, commanded clamping force, and measured clamping force of the wrist jaws when the control system limits the measured clamping force to a pre-specified maximum threshold during jaw closure in position mode, according to various aspects of the subject matter.

[0020] Figure 7 This is a flowchart illustrating a method for feedback control of a surgical robotic system according to various aspects of the subject matter, which limits the clamping force of the wrist jaws to a pre-specified maximum threshold during jaw closure in a position mode by analyzing the desired jaw angle and the measured clamping force.

[0021] Figure 8A It is a time curve showing the command jaw angle, measured jaw angle, command clamping force, and measured opening force of the wrist jaws when the measured opening force is not maintained above the minimum level while the jaws are in the open position mode.

[0022] Figure 8B This is a time graph showing the commanded jaw angle, measured jaw angle, commanded clamping force, and measured opening force of the wrist jaws when the control system maintains the measured opening force above a pre-specified minimum opening force threshold during jaw opening in position mode, according to various aspects of the subject matter technology.

[0023] Figure 9 This is a flowchart illustrating a method for feedback control of a surgical robotic system according to various aspects of the subject matter, which maintains the opening force of the wrist jaw above a pre-specified minimum opening force threshold during jaw opening in a position mode by analyzing the desired jaw angle, the estimated jaw angle, and the measured opening force.

[0024] Figure 10 This is a block diagram of an exemplary control system according to various aspects of the subject matter, which is used to control the position and clamping force of an end effector when the end effector of a robotic surgical tool is in a position mode or a force mode, or when the end effector transitions between a position mode and a force mode.

[0025] Figure 11AThis is a time-varying graph showing the commanded jaw angle, measured jaw angle, commanded clamping force, measured clamping force, and the activity of the clamping force controller when the jaw angle is set near the threshold between position mode and force mode without a stabilization algorithm.

[0026] Figure 11B This is a time-varying graph showing the commanded jaw angle, measured jaw angle, commanded clamping force, measured clamping force, and the activity of the clamping force controller of the wrist jaw when the control system uses an anti-shake algorithm with the jaw angle set near a threshold between the position mode and the force mode, according to various aspects of the subject matter technology.

[0027] Figure 12A This is a time curve showing the commanded jaw angle, measured jaw angle, commanded clamping force, and measured clamping force of the wrist jaws when the jaws change from position mode to force mode and back to position mode without constraint.

[0028] Figure 12B This is a time graph showing the commanded jaw angle, measured jaw angle, commanded clamping force, and measured clamping force of the wrist jaw as the control system constrains the change in clamping force as the jaws switch between position mode and force mode, according to various aspects of the subject matter technology.

[0029] Figure 13 This is a flowchart illustrating a method for feedback control of a surgical robot system according to various aspects of the subject matter, which employs an anti-shake algorithm when setting a desired jaw angle of the wrist jaw near a threshold between a position mode and a force mode, or limits variations in measured clamping force when the jaw transitions between a position mode and a force mode.

[0030] Figure 14 This is a block diagram illustrating exemplary hardware components of a surgical robotic system according to various aspects of the subject matter. Detailed Implementation

[0031] Examples of various aspects and variations of this subject matter are described herein and illustrated in the accompanying drawings. The following description is not intended to limit the invention to these embodiments, but rather to enable those skilled in the art to make and use the invention.

[0032] This invention discloses a feedback control system and method for controlling the clamping or opening force of end effectors (such as wrist jaws) of a surgical robotic arm. The wrist jaws can be cable-connected to actuators of a tool drive device for multi-axis motion. The feedback control system can command pitch, yaw, and jaw angles between the wrist jaws and the jaws. When the commanded jaw angle is above a threshold (also known as a detent threshold), the wrist jaws can operate in a position mode to move to a commanded position and orientation. The commanded jaw angle can also be referred to as the desired jaw angle. When the commanded jaw angle is below the detent threshold, the wrist jaws can operate in a force mode based on the position and orientation of the position mode, and a desired clamping force is generated by a clamping force controller based on the commanded jaw angle. In one embodiment, when the jaws are closing in a position mode, the feedback control system can limit the maximum clamping force by analyzing the desired jaw angle and measuring or estimating the actually applied clamping force to determine whether the measured clamping force exceeds a pre-specified maximum clamping force threshold. If so, the feedback control system can calculate the clamping force error to adjust the clamping force so that the measured clamping force is limited to a pre-specified maximum clamping force threshold.

[0033] In one implementation, the feedback control system can maintain a minimum jaw opening force when the jaws are open in a position mode. The feedback control system can measure or estimate the actual applied jaw angle. It can also measure or estimate the actual applied clamping or opening force of the jaws. By analyzing the desired jaw angle, the measured jaw angle, and the measured jaw opening force, the feedback control system can determine whether the jaws are in a position mode, whether the difference between the desired and estimated jaw angles is greater than a threshold, and whether the measured jaw opening force is less than a pre-specified minimum opening force threshold. If so, the feedback control system can calculate an opening force error to adjust the clamping or opening force to maintain the measured jaw opening force above the pre-specified minimum opening force threshold.

[0034] In one implementation, the feedback control system may use an anti-shake algorithm to prevent the wrist jaws from oscillating between position and force modes when a jaw angle is set near braking. The feedback control system may determine whether the desired angle is less than a braking threshold for a pre-specified duration. If so, the feedback control system may switch the wrist jaws from position mode to force mode. In one implementation, the anti-shake algorithm may be unilateral, such that the wrist jaws can switch back to position mode whenever the desired jaw angle is greater than or equal to the threshold.

[0035] In one implementation, the feedback control system minimizes undesirable abrupt changes in clamping force when transitioning between position and force modes. The clamping force controller calculates the current command for the desired clamping force based on the desired jaw angle. The feedback control system can measure or estimate the actual applied clamping force. The feedback control system can analyze the desired jaw angle, the desired clamping force, and the measured clamping force to determine whether the jaws are transitioning from position to force mode, whether the error between the measured clamping force and the desired clamping force exceeds a pre-specified maximum force error, and whether the desired clamping force is increasing. If so, when transitioning from position to force mode, the feedback control system can set the clamping force to the measured clamping force minus a pre-specified margin.

[0036] In one implementation, the feedback control system analyzes the desired jaw angle, desired clamping force, and measured clamping force to determine whether the jaws are transitioning from a force mode to a position mode, whether the desired clamping force is less than a pre-specified minimum clamping force value, whether the desired clamping force is decreasing, and whether the absolute value of the error between the measured clamping force and the minimum clamping force is less than a pre-specified maximum force error. If so, when transitioning from a force mode to a position mode, the feedback control system can set the clamping force to the pre-specified minimum clamping force value. In one implementation, the pre-specified minimum clamping force value can be set to 3N.

[0037] Figure 1 This is a drawing view of an exemplary surgical robotic system 1 in an operating room, according to various aspects of the subject matter. The robotic system 1 includes a user console 2, a control tower 3, and one or more surgical robotic arms 4 at a surgical robotic platform 5 (e.g., a table, bed, etc.). The arms 4 can be mounted to the table or bed where the patient lies, such as... Figure 1 As shown in the examples, they can also be mounted on a trolley separate from the table or bed. System 1 can incorporate any number of devices, tools, or accessories for performing surgery on patient 6. For example, system 1 may include one or more surgical tools 7 for performing surgical procedures. Surgical tool 7 may be an end effector attached to the distal end of surgical arm 4 for performing surgical procedures.

[0038] Each surgical tool 7 can be manually manipulated, robotically manipulated, or both during surgery. For example, surgical tool 7 can be a tool for accessing, viewing, or manipulating the internal anatomy of patient 6. In one aspect, surgical tool 7 is a gripper such as a wrist clamp capable of grasping patient tissue. Surgical tool 7 can be configured to be manually controlled by bedside operator 8, robotically controlled via actuated movement of its attached surgical robotic arm 4, or both. The robotic arm 4 is shown as table-mounted, but in other configurations, arm 4 may be mounted to a trolley, ceiling, or sidewall, or to another suitable structural support.

[0039] A remote operator 9 (such as a surgeon or other human operator) can use the user console 2 to remotely manipulate the arm 4 and its attached surgical instruments 7, referred to herein as remote manipulation. The user console 2 may be located in the same operating room as the rest of the system 1, such as... Figure 1 As shown. However, in other environments, the user console 2 may be located in an adjacent or nearby room, or it may be located in a remote location, such as in a different building, city, or country. The user console 2 may include a seat 10, foot controls 13, one or more handheld user input devices (UIDs) 14, and at least one user display 15 configured to display a view, for example, of a surgical site within a patient 6. In the exemplary user console 2, a remote operator 9 sits in the seat 10 and views the user display 15 while manipulating the foot controls 13 and the handheld UID 14 to remotely control the arm 4 and the surgical instruments 7 mounted on the distal end of the arm 4.

[0040] In some variations, the bedside operator 8 can operate the system 1 in a "bedside" mode, where the bedside operator 8 (the user) is positioned to one side of the patient 6 and simultaneously manipulates robotically driven tools (end-effectors attached to arm 4), holding a handheld UID 14 in one hand and a manual laparoscopic tool in the other. For example, the bedside operator's left hand can manipulate the handheld UID to control the robotically driven tools, while the bedside operator's right hand can manipulate the manual laparoscopic tool. In this particular variation of system 1, the bedside operator 8 can perform both robot-assisted minimally invasive surgery and manual laparoscopic surgery on the patient 6.

[0041] During the exemplary procedure (surgical operation), patient 6 is prepared for surgery and aseptically covered with a sterile drape to administer anesthesia. Initial access to the surgical site can be manually performed (to facilitate access to the surgical site) while the arms of robotic system 1 are in a retracted or withdrawn configuration. Once access is complete, initial positioning or preparation of robotic system 1, including its arms 4, can be performed. The surgery then continues, with remote operator 9 at user console 2 using foot controls 13 and UID 14 to manipulate various end effectors and, possibly, imaging systems to perform the surgery. Artificial assistance can also be provided at the operating table or surgical table by a bedside person (e.g., bedside operator 8) wearing sterile surgical gowns, who can perform tasks on one or more arms of robotic arms 4, such as tissue retraction, manual repositioning, and tool changes. Non-sterilized personnel may also be present to assist remote operator 9 at user console 2. When a procedure or surgical operation is completed, System 1 and User Console 2 can be configured or set to a certain state to facilitate the completion of postoperative procedures, such as cleaning or disinfection, and the input or printing of health records via User Console 2.

[0042] In one embodiment, the remote operator 9 holds and moves UID 14 to provide input commands, thereby moving the robotic arm actuator 17 in the robotic system 1. UID 14 may be communicatively coupled to the rest of the robotic system 1, for example, via a console computer system 16. UID 14 may generate spatial state signals corresponding to the movement of UID 14, such as the position and orientation of the UID's handheld housing, and the spatial state signals may be input signals for controlling the movement of the robotic arm actuator 17. The robotic system 1 may use control signals derived from the spatial state signals to control the proportional movement of the actuator 17. In one embodiment, a console processor of the console computer system 16 receives the spatial state signals and generates corresponding control signals. Based on these control signals controlling how the actuator 17 is energized to move a segment or connector of the arm 4, the movement of a corresponding surgical tool attached to the arm may simulate the movement of UID 14. Similarly, the interaction between the remote operator 9 and UID 14 may generate, for example, a clamping control signal that causes the jaws of the gripper of the surgical tool 7 to close and clamp the tissue of the patient 6.

[0043] The surgical robot system 1 may include a plurality of UIDs 14, wherein a corresponding control signal is generated for each UID that controls the actuators and surgical instruments (end-effectors) of a respective arm 4. For example, a remote operator 9 may move a first UID 14 to control the movement of an actuator 17 located in the left robotic arm, wherein the actuator responds by moving links, gears, etc. in the arm 4. Similarly, movement of a second UID 14 by the remote operator 9 controls the movement of another actuator 17, which in turn moves other links, gears, etc. of the robot system 1. The robot system 1 may include a right arm 4 fixed to a bed or table on the right side of the patient, and a left arm 4 located on the left side of the patient. The actuators 17 may include one or more motors controlled to drive the joints of the arm 4 to rotate, for example, relative to the patient, changing the orientation of the endoscope or gripper of the surgical instrument 7 attached to the arm. The movement of a plurality of actuators 17 in the same arm 4 may be controlled by spatial state signals generated from a particular UID 14. The UID 14 may also control the movement of the corresponding surgical instrument gripper. For example, each UID 14 can generate a corresponding gripping signal to control the movement of an actuator (e.g., a linear actuator) that opens or closes the jaws of a gripper at the distal end of the surgical tool 7 to grip tissue in the patient 6.

[0044] In some respects, communication between platform 5 and user console 2 can be achieved via control tower 3, which translates user commands received from user console 2 (and more specifically from console computer system 16) into robot control commands transmitted to arm 4 on robot platform 5. Control tower 3 can also transmit status and feedback from platform 5 back to user console 2. The communication connection between robot platform 5, user console 2, and control tower 3 can be via wired and / or wireless links, using any suitable data communication protocol from a variety of data communication protocols. Any wired connection can optionally be integrated into the floor and / or walls or ceiling of the operating room. Robot system 1 can provide video output to one or more displays, including displays within the operating room and remote displays accessible via the Internet or other networks. Video output (video feed) can also be encrypted to ensure privacy, and all or part of the video output can be stored on a server or electronic healthcare record system.

[0045] Figure 2 This is a schematic diagram illustrating an exemplary design of a robotic arm, tool drive, and cannula loaded with robotic surgical tools according to various aspects of the subject matter. Figure 2As shown, the exemplary robotic arm 112 may include a plurality of connectors (e.g., connector 202) and a plurality of engagement modules (e.g., engagement 204) for actuating the plurality of connectors relative to each other. The engagement modules may include various engagement types, such as pitch engagements or roll engagements, which can substantially constrain the movement of adjacent connectors about certain axes relative to other axes. Figure 2 An exemplary design also illustrates a tool drive 210 attached to the distal end of a robotic arm 112. The tool drive 210 may include a cannula 214 coupled to its end for receiving and guiding surgical instruments 220 (e.g., endoscopes, sutures, etc.). The surgical instrument (or “tool”) 220 includes an end effector 222 located at the distal end of the tool. Multiple engagement modules of the robotic arm 112 are actuable to position and orient the tool drive 210, which actuates the end effector 222 to perform robotic surgery.

[0046] Figure 3A and Figure 3B This is a schematic diagram illustrating exemplary tool drive devices, respectively having and not having loaded tools, according to various aspects of the subject matter. For example... Figure 3A and Figure 3B As shown, in one variation, the tool drive 210 may include an elongated base (or “tower”) 310 having a longitudinal rail 312 and a tool holder 320 slidably engaged with the longitudinal rail 312. The tower 310 may be configured to be coupled to the distal end of a robotic arm such that joint movements of the robotic arm position and / or orient the tool drive 210 in place. Additionally, the tool holder 320 may be configured to receive a tool base 352 for a tool 220, which may also include a tool shaft 354 extending from the tool base 352 and through a sleeve 214, wherein an end effector 222 (not shown) is disposed at the distal end.

[0047] Additionally, the tool holder 320 can actuate a set of joints of the end effector via a cable system or line manipulated and controlled by an actuation drive (the terms "cable" and "line" are used interchangeably throughout this application). The tool holder 320 may include different configurations with actuation drives. For example, a rotary shaft drive may include a motor with a hollow rotor and a planetary gear transmission at least partially disposed within the hollow rotor. Multiple rotary shaft drives may be arranged in any suitable manner. For example, the tool holder 320 may include six rotary drives 322A-322F arranged in two rows extending longitudinally along the base, slightly staggered to reduce the width of the holder and increase the compact nature of the tool drives. Figure 3BAs clearly shown, rotary drive units 322A, 322B and 322C can typically be arranged in the first row, while rotary drive units 322D, 322E and 322F can typically be arranged in the second row, which is slightly longitudinally offset from the first row.

[0048] Figure 4A and Figure 4B This describes an exemplary gripper end effector according to various aspects of the subject matter, having a robotic wrist, a pair of opposing jaws, and a pulley and cable system for coupling the robotic wrist and the jaws to an actuator of a tool drive mechanism. It should be noted that although the following tool model and controller design are described with reference to an exemplary surgical robotic gripper, the proposed control system for position and gripping force control is adaptable to any tool including an end effector coupled to a tool axis via a robotic wrist that allows for multi-axis movement (e.g., pitch and yaw) of the end effector. Similar tools include, but are not limited to, grippers, clamps, forceps, needle actuators, retractors, and cauterization instruments.

[0049] like Figure 4A As shown, a pair of opposing jaws 401A and 401B are movably coupled to a first yoke 402 of the robot wrist via an extension shaft 412 along a first axis 410. The first yoke 402 is movably coupled to a second yoke 403 of the robot wrist via a second extension shaft 422 along a second axis 420. The pair of jaws 401A and 401B can each be coupled to or integrally formed with pulleys 415A and 415B via the extension shaft 412, such that both jaws can rotate about axis 410. Pulleys 425A, 425B, 425C, and 425D are coupled to the extension shaft 422 and rotate about axis 420. Pulleys 425A, 425B, 425C, and 425D are arranged as a first set of pulleys 425B and 425C on one side of the yoke 402 and a second set of pulleys 425A and 425D on the other side of the yoke 402. Pulleys 425A and 425C are outer pulleys, and pulleys 425B and 425D are inner pulleys. Similarly, the third set of pulleys 435A, 435B, 435C, and 435D are coupled to the third extension shaft 432 and rotate about the axis 430 which is parallel to the axis 420.

[0050] The gripper 220 can be actuated to move one or both of the jaws 401A and 401B about axis 410 in various ways. For example, jaws 401A and 401B can open and close relative to each other. Jaws 401A and 401B can also be actuated to rotate together as a pair to provide deflection motion of the gripper 220. Furthermore, the first yoke 402, pulleys 415A and 415B, and jaws 401A and 401B can rotate about axis 420 to provide pitch motion of the gripper 220. Movement of the jaws of the robot wrist and / or tool can be actuated by controlling four independent cables 405A-405D. Figure 4A As shown, cable 405A may begin (or terminate) on one side of pulley 415A and be routed along pulleys 425A and 435A, and cable 405B is configured to terminate on the other side of pulley 415A and be routed through pulleys 425B and 435B. Similarly, another pair of cables 405C and 405D may be coupled to jaw 401B. For example, cable 405C extends from one side of pulley 415B to pulleys 425C and 435C; and cable 405D is routed through pulleys 425D and 435D and terminates on the other side of pulley 415B. A third set of pulleys 435A, 435B, 435C, and 435D are arranged in such a way that cables 405A-405D remain attached to the second set of pulleys 425A-425D and slippage or sliding of the cables relative to pulleys 425A-425D is prevented.

[0051] like Figure 4A and Figure 4B As shown, the gripper 220 can be actuated to move the jaws 401A and 401B in various ways, such as by imparting motion to one or more of the pulleys 425A, 415B, 415A, 425B, 425C, and 425D to thereby impart motion to the first yoke 402 and / or one or both of the jaws 401A and 401B, to perform gripping (e.g., the jaws rotate independently about axis 410), deflection (e.g., the jaws rotate together about axis 410), and pitching (e.g., the jaws rotate about axis 420). The cables 405A-405D can be divided into two opposing pairs, such that when one cable in the opposing pair is actuated or tensioned while the other cable is released, the jaws will rotate in one direction. When only the other cable is tensioned, the jaws will rotate in the opposite direction.

[0052] For example, cables 405A and 405B are a first pair of opposing forces for moving jaws 401A, and cables 405C and 405D are a second pair of opposing forces for controlling jaws 401B. When cable 405A is tensioned (e.g., by at least one of the rotary drive devices 322a-322f) and cable 405B is released, jaws 401A close (moving toward the opposing jaws 401B). On the other hand, when cable 405B is tensioned and cable 405A is released, jaws 401A open (moving away from the opposing jaws 401B). Similarly, when tensioned, cable 405C closes jaws 401B (moving toward the opposing jaws 401A), and cable 405D opens jaws 401B (moving away from the opposing jaws 401A), while the other cable is released. As another example, the clamping force between jaws 401A and 401B can be achieved by continuing to tension cables 405A and 405C after the jaws are closed (in contact with each other) while simultaneously releasing cables 405B and 405D.

[0053] When two cables of one pair are simultaneously tensioned while two cables of another pair are released, pulley 415A or pulley 415B does not rotate. Instead, the first yoke 402, together with jaws 401A and 401B, is given pitch about axis 420 by pulleys 415A and 415B. For example, when a pair of cables 405A and 405B are simultaneously tensioned while a pair of cables 405C and 405D are released, the jaws (together with the yoke 402) pitch out of the paper plane. However, when two cables 405C and 405D are simultaneously tensioned and the pair 405A and 405B remain released, the jaws pitch into the paper plane.

[0054] Figure 4B This is a schematic diagram illustrating exemplary angular definitions for various movements of the gripper 220 according to various aspects of the subject matter. The angles are defined with reference to axes 410 and 420, and to axis 452 of the first yoke 402 and axis 453 of the second yoke 403. For example, as... Figure 4B As shown, the angle (θ1) between axes 452 and 453 can represent the rotation angle of the yoke 402 about axis 420. This rotation angle can also be defined as the pitch angle (θ) of the gripper 220. 俯仰 (and in) Figure 4A In this configuration, the axis 452 of the yoke 402 is superimposed on the axis 453 of the yoke 403 because the jaws remain in the reference position (i.e., without pitch motion). Furthermore, angles (θ2) and (θ3) can represent the angles between each of the jaws 401A and 401B and the axis 452 of the yoke 402 (as the origin), respectively. To distinguish the sides of the axis 452, angles (θ2) and (θ3) can take different signs. For example, as... Figure 4B As shown, angle (θ2) is negative and angle (θ3) is positive.

[0055] To perform control tasks, it is often beneficial to define a consistent coordinate system for the joint angles. For example, we can further define the jaw angles (θ) as follows: 钳口 The angle (θ) is defined as the angle between the two jaws 401A and 401B, and the deflection angle (θ) is defined as the angle between the jaws 401A and 401B. 偏转 The pitch angle (θ) is defined as the angle between the axis 45° and the line bisecting the jaw angle. As mentioned above, the pitch angle (θ) 俯仰 θ can be defined as the angle (θ1) between axis 452 and axis 453. Therefore:

[0056]

[0057] The following describes a method and system for controlling the angular position and gripping force of a distal end effector of a robotic surgical instrument. The end effector may include a robotic wrist and a pair of opposing components (e.g., jaws or claws), each movable between an open and closed position, actuated by two opposing wires. A total of four wires may be driven independently by actuators or motors, as in… Figure 3A , Figure 3B and Figure 4A , Figure 4B As shown in the diagram. The control system may include feedback loops involving position and velocity feedback from the actuators and force feedback measured on four wires to achieve desired position and clamping force. In some implementations, the actuator controller may operate in a position plus feedforward current mode. For example, in position mode, the position controller may drive the distal end effector to a desired angular position in space based on position feedback, while in force mode, the clamping force controller provides additional feedforward current based on the clamping force measured by force sensors on four wires to achieve the desired clamping force between the relative components.

[0058] Figure 5 This is a block diagram illustrating an advanced control system for controlling surgical tools according to various aspects of the subject matter. The control system includes an input 560, a controller 562, a device 564, an output 568, and sensors and estimators 566 on the feedback path between the output 568 and the controller 562. The device 564 may include a tool actuator and an end effector (e.g., Figure 3B Rotary drive unit 322A-322F and Figure 4A The wrist clamp jaws cable 405A-405D; see also Figure 10 The actuator unit 510 and the cable and wrist linkage 512 are included. The controller 562 may include one or more processors configured by software instructions stored in memory to calculate the movement of the device 564 in response to input 560, which may indicate the desired movement of the end effector of the surgical tool, such as... Figure 4BThe expected θ of the wrist jaws 俯仰 Expected θ 偏转 and expected θ 钳口 Therefore, the commands generated by controller 562 can drive the tool actuator to facilitate the desired movement of the end effector. In one embodiment, the desired θ 俯仰 θ 偏转 and θ 钳口 It is possible Figure 1 The output 568 (such as position, speed, cable tension, and clamping or opening force of the end effector) can be directly measured or estimated by the sensor and estimator 566 and fed back to the controller 562 for closed-loop control.

[0059] In one implementation, when the desired jaw angle θ of the wrist jaws... 钳口 When it is greater than or equal to the threshold, it is also called command θ. 钳口 Expected θ 钳口 This can be considered a position control command in position mode. The threshold is used to determine braking and can correspond to the angle at which both jaws just simultaneously contact the object between them. When there is no object to grip, the threshold is zero degrees when the jaws begin to touch each other. In position mode, the controller 562 can determine the desired θ. 钳口 and expected θ 俯仰 and expected θ 偏转 This is converted into a corresponding actuator position command to drive the wrist jaws to the desired position and orientation. When the desired θ... 钳口 When the position is below a threshold, the wrist jaws operate in force control mode, or simply force mode, and the desired jaw angle is converted into a desired clamping force command. In addition to position commands, the controller 562 can also generate current commands to achieve the desired clamping force.

[0060] In one implementation, controller 562 can limit the maximum clamping force when the jaws are closed in a position mode to prevent damage to tissue that can be grasped by the jaws. The clamping force of the jaws can be estimated or measured by sensor and estimator 566. Controller 562 can analyze the expected θ 钳口 The controller 562 measures the clamping force to determine whether the jaws are closed in the position mode and whether the measured clamping force exceeds a pre-specified maximum clamping force threshold. If so, the controller 562 can calculate a clamping force error to limit the measured clamping force to the pre-specified maximum clamping force threshold. For example, to determine whether the jaws are closed in the position mode, the controller 562 can first verify the expected θ 钳口 The braking threshold is greater than or equal to the braking threshold, and therefore persists for more than a pre-specified duration in position mode. The controller 562 can employ anti-shake technology to verify the desired θ. 钳口The duration has been reduced to the pre-specified duration. In one implementation, if θ is desired... 钳口 If the data is sampled at a periodic frequency, the controller 562 can verify the expected θ. 钳口 The sample size has been reduced from the pre-specified number of samples.

[0061] To determine whether the measured clamping force exceeds a pre-specified maximum clamping force threshold, the controller 562 may also employ anti-shake technology. In one implementation, Figure 5 The feedback control loop of the control system can operate in loop cycle time. The clamping force counter can increment by one count for each control loop cycle during which the measured clamping force is less than the maximum clamping force threshold minus a margin. In one embodiment, the clamping force counter can stop incrementing after reaching its maximum count. The clamping force counter can be reset when the measured clamping force exceeds the maximum clamping force threshold. When the measured clamping force exceeds the maximum clamping force minus a margin anywhere within the window, the anti-shake technology can declare that the measured clamping force exceeding the maximum clamping force threshold continues across the entire window equal to the number of loop cycles of the clamping force counter.

[0062] As an example, suppose the measured clamping force is initially below the maximum clamping force threshold minus a margin, and the clamping force counter is incrementing. When the measured clamping force increases beyond the maximum clamping force threshold, the clamping force counter can be reset. The feedback control loop of controller 562 can attempt to change the actuator position command to drive the wrist jaws, thereby limiting the measured clamping force to the maximum clamping force threshold. However, even if the measured clamping force drops below the maximum clamping force threshold but remains above the maximum clamping force threshold minus a margin, the feedback control loop can still consider the measured clamping force to be greater than the maximum clamping force threshold in order to limit the maximum measured clamping force. Suppose the measured clamping force drops below the maximum clamping force threshold minus a margin for only a few loop cycles, but then increases again above this level. The clamping force counter can be incremented up to the number of loop cycles in which the measured clamping force briefly falls below the maximum clamping force threshold minus a margin. As long as the measured clamping force remains above the maximum clamping force threshold minus the margin within a window equal to the number of loop cycles spanning the clamping force counter (e.g., the measured clamping force briefly drops below the maximum clamping force threshold minus the margin), the feedback control loop can still assume that the measured clamping force is greater than the maximum clamping force threshold for the entire duration of that window, in order to limit the maximum measured clamping force.

[0063] When controller 562 determines that the jaws are closed in position mode and the measured clamping force exceeds a maximum clamping force threshold, the controller can limit the measured clamping force to the maximum clamping force threshold. In one embodiment, controller 562 can calculate a clamping force error, which is the difference between the maximum clamping force threshold and the measured clamping force. A zero-steady-state controller (such as a proportional-integral (PI) force controller) can be deployed to receive the clamping force error, thereby maintaining or limiting the measured clamping force at the maximum clamping force threshold. The output of the PI force controller can be combined with the output of an inverse kinematics matrix that operates on errors in the desired position and orientation of the wrist jaws to generate a compensated actuator position command. The compensated actuator position command is added to the existing actuator position command to drive the wrist jaws, thereby limiting the maximum amount of clamping force when the jaws are closed in position mode at the desired position and orientation.

[0064] Figure 6A This illustrates the command θ of the wrist jaws when the measured clamping force 609 is unrestricted while the jaws are closed in position mode. 钳口 603. Measured θ 钳口 605. Time curves of commanded clamping force 607 and measured clamping force 609. Threshold θ between position mode and force mode. 钳口 Set to zero, so that when command θ 钳口 When 603 is greater than or equal to zero degrees, the wrist jaws operate in position mode. When the command θ... 钳口 When 603 is less than zero degrees, the wrist jaws operate in force mode.

[0065] Figure 6A The wrist jaws were shown operating in position mode from 20 to 35 seconds and again from 44 to 47 seconds. The measured θ... 钳口 605 remains within a relatively narrow range, even when command θ 钳口 The same applies when 603 changes within position mode or force mode, presumably because the jaws are gripping an object. During position mode, the command clamping force 607, as the desired clamping force, can be set to a default value of zero N because the wrist jaws are not operating in force mode. However, the measured clamping force 609 can be much larger. For example, from 26 to 28 seconds and from 31 to 35 seconds, when the jaws are closed or held in the closed position in position mode, the measured clamping force 609 exceeds 10 N and can be as high as 15 N because the measured clamping force is unrestricted. In force mode (e.g., 35-44 seconds and after 47 seconds), the clamping force controller can set the command clamping force 607 to the command θ. 钳口 The function is 603, and the feedback control loop can keep the measured clamping force 609 the same as the commanded clamping force 607.

[0066] Figure 6B This illustrates, according to various aspects of the subject matter, that when the control system limits the measured clamping force to a pre-specified maximum threshold 617 during jaw closure in position mode, the wrist jaw command θ 钳口 613. Measured θ 钳口 615. Time curve of commanded clamping force 617 and measured clamping force 619. The maximum clamping force threshold is set to 8.5N.

[0067] exist Figure 6B In the middle, when the measured clamping force is unrestricted, command θ 钳口 613 and the measured θ 钳口 The time curve of 615 and Figure 6A command θ 钳口 603 and the measured θ 钳口 Same as 605. During position mode, the commanded clamping force 617 is again set to the default value of zero N by the clamping force controller. However, when the jaws are closing or held in the closed position (e.g., 27-30 seconds, 32-36 seconds, and 41-45 seconds), during position mode, the measured clamping force 619 is limited by the clamping force controller to a maximum clamping force threshold of 8.5 N. Furthermore, the limitation of the maximum clamping force in position mode has no effect on force mode. Therefore, in force mode, the measured clamping force 619 is allowed to exceed the maximum clamping force threshold of 8.5 N by following the commanded clamping force 617.

[0068] Figure 7 This is a flowchart illustrating a method 700 for feedback control of a surgical robotic system according to various aspects of the subject matter. This method limits the clamping force of the wrist jaws to a pre-specified maximum threshold during jaw closure in a position mode by analyzing the desired jaw angle and measured clamping force. Method 700 can be derived from... Figure 5 The control system is implemented by controller 562, which receives the desired θ from user input. 钳口 It also receives the measured clamping force from the sensor and estimator 566 to generate actuator position commands for driving the wrist jaws.

[0069] In block 701, method 700 determines whether the wrist jaws are in a position mode. In one implementation, block 701 may determine the desired θ. 钳口 Is it greater than or equal to the threshold θ between the position mode and the force mode? 钳口 The process continues for more than a pre-specified period of time to confirm that the wrist jaws are in position mode. In one implementation, a threshold θ is used. 钳口It can be set to zero. If the wrist jaws are not in position mode, the wrist jaws are in force mode and the clamping force is unrestricted. In block 709, method 700 generates an actuator position command without imposing a constraint on the clamping force. In one embodiment, in addition to generating the actuator position command, block 709 will also expect θ 钳口 Convert into a desired clamping force command to achieve the desired clamping force.

[0070] If the jaws are in position mode, block 703 determines whether the jaws are closing. In one embodiment, block 703 may employ debouncing technology to determine the desired θ. 钳口 Has the pre-specified duration or the pre-specified number of samples been reduced? In one implementation, if θ is expected... 钳口 If the jaws remain stationary without increasing, they can be considered to be closing. If the jaws are not closing, the clamping force is unrestricted even in position mode. Method 700 defaults to block 709 to generate actuator position commands without imposing constraints on the clamping force.

[0071] If the jaws are closed in position mode, block 705 determines whether the measured clamping force exceeds a pre-specified maximum clamping force threshold. In one embodiment, block 705 may employ anti-jitter technology to determine whether the measured clamping force is greater than the maximum clamping force threshold minus any margin that spans anywhere within a window equal to the number of samples from the clamping force counter. In one embodiment, the measured clamping force can be... Figure 5 The clamping force is sampled at the loop cycle time of the feedback control system. The clamping force counter can increment by one for each control loop cycle during which the measured clamping force is less than the maximum clamping force threshold minus a margin. The clamping force counter can be reset when the measured clamping force exceeds the maximum clamping force threshold. The measured clamping force is considered to exceed the maximum clamping force threshold for the entire window as long as the measured clamping force exceeds the maximum clamping force threshold minus a margin spanning any point within a window equal to the number of samples from the clamping force counter. Otherwise, the measured clamping force does not exceed the maximum clamping force threshold, and method 700 defaults to block 709 to generate an actuator position command without imposing a constraint on the clamping force.

[0072] If the measured clamping force exceeds the maximum clamping force threshold while the jaws are closed in position mode, block 707 generates a compensated actuator position command to limit the measured clamping force to the maximum clamping force threshold. In one embodiment, block 707 may calculate a clamping force error, which is the difference between the maximum clamping force threshold and the measured clamping force. A zero-steady-state controller (such as a proportional-integral (PI) force controller) may receive the clamping force error to generate a compensated clamping force command. The output of the PI force controller may be combined with the output of an inverse kinematics matrix that operates on errors in the desired position and orientation of the wrist jaws to generate a compensated actuator position command. The compensated actuator position command may be added to an existing actuator position command to drive the jaws to limit the measured clamping force to the maximum clamping force threshold.

[0073] On another front, when operating in position mode, controller 562 can maintain a minimum jaw opening force via the wrist jaws. This minimum jaw opening force can also be referred to as the minimum clamping force. Maintaining a minimum jaw opening force when the jaws are open in position mode helps the jaws overcome resistance that might prevent them from opening to the desired jaw angle. The jaw angle and opening force can be estimated or measured by the sensor and estimator 566. Controller 562 can analyze the desired θ. 钳口 , estimated θ 钳口 The measured opening force is used to determine whether the jaws are opening in position mode, with an expected θ. 钳口 With the estimated θ 钳口 The controller 562 checks whether the jaw angle error between the measured force and the pre-specified minimum jaw opening force threshold is greater than a threshold, and whether the measured opening force is lower than a pre-specified minimum jaw opening force threshold. If so, the controller 562 calculates the opening force error between the pre-specified minimum jaw opening force threshold and the measured opening force to ensure that the measured opening force is higher than the pre-specified minimum jaw opening force threshold.

[0074] In one implementation, to determine whether the jaws are open in position mode, the controller 562 can first verify the expected θ 钳口 The braking threshold is greater than or equal to the braking threshold, and therefore persists in position mode for more than a pre-specified duration. The controller 562 can then determine whether the jaws opened in position mode satisfy the requirement to prevent the jaws from opening to the desired θ. 钳口 The resistance. In one implementation, the controller 562 may employ anti-jitter technology to verify the desired θ. 钳口 Greater than the estimated θ 钳口 And as the expected θ 钳口 With the estimated θ 钳口 The difference θ between 钳口 Error greater than θ 钳口 The error threshold persists for a pre-specified duration. In one implementation, if θ is desired...钳口 and estimated θ 钳口 If samples are taken at a periodic frequency, the controller 562 can verify θ for a pre-specified number of samples. 钳口 Error greater than θ 钳口 Error threshold.

[0075] To determine whether the measured opening force is below a pre-specified minimum jaw opening force threshold, the controller 562 may also employ anti-jitter technology. A jaw opening force counter may increment by one for each control loop cycle during which the measured opening force is greater than the minimum opening force threshold plus a margin. In one embodiment, the jaw opening force counter may stop incrementing after reaching its maximum count. The jaw opening force counter may reset when the measured opening force is less than the minimum jaw opening force threshold. When the measured opening force is less than the minimum jaw opening force threshold plus a margin anywhere within the window, the anti-jitter technology may declare that the measured opening force being less than the minimum jaw opening threshold persists across the entire window equal to the number of loop cycles of the jaw opening force counter.

[0076] As an example, suppose the measured opening force is initially higher than the minimum jaw opening force threshold plus a margin, and the jaw opening force counter is incrementing. When the measured opening force drops below the minimum jaw opening force threshold, the jaw opening force counter can be reset. The feedback control loop of controller 562 can attempt to change the actuator position command to drive the wrist jaws, thereby keeping the measured opening force above the minimum jaw opening force threshold. However, even if the measured opening force increases to above the minimum jaw opening force threshold but remains below the minimum jaw opening force threshold plus a margin, the feedback control loop can still consider the measured opening force to be less than the minimum jaw opening force threshold in order to maintain the minimum jaw opening force. Suppose the measured opening force rises above the minimum jaw opening force threshold plus a margin for only a few loop cycles, but then drops below this level again. The jaw opening force counter can be incremented up to the number of loop cycles in which the measured opening force is briefly above the minimum jaw opening force threshold plus a margin. As long as the measured opening force remains below the minimum jaw opening force threshold plus a margin within a window equal to the number of loop cycles spanning the jaw opening force counter (e.g., the measured opening force is briefly above the minimum jaw opening force threshold plus the margin number of loop cycles), the feedback control loop can still assume that the measured opening force is less than the minimum jaw opening force threshold for the entire duration of that window in order to maintain the minimum jaw opening force.

[0077] When controller 562 determines that the jaws are open in position mode, θ 钳口 Error greater than θ 钳口If an error threshold is set and the measured opening force is lower than a pre-specified minimum jaw opening force threshold, the controller can maintain the measured opening force above the minimum jaw opening force threshold. In one embodiment, the controller 562 can calculate a jaw opening force error, which is the difference between the minimum jaw opening force threshold and the measured opening force. A zero-steady-state controller (such as a proportional-integral (PI) force controller) can be deployed to receive the jaw opening force error, thereby maintaining the measured opening force at or above the minimum jaw opening force threshold. The output of the PI force controller can be combined with the output of an inverse kinematics matrix that operates on errors in the desired position and orientation of the wrist jaws to generate a compensated actuator position command. The compensated actuator position command is added to an existing actuator position command to drive the wrist jaws, thereby maintaining a minimum amount of opening force when the jaws are opening in position mode at the desired position and orientation.

[0078] Figure 8A This indicates the wrist jaw command θ when the measured opening force does not remain above the minimum level while the jaws are in position mode and open. 钳口 803. Measured θ 钳口 805. Time curves of commanded clamping force 807 and measured opening force 809. The threshold θ jaw between position mode and force mode is set to zero, so that when commanded θ jaw 603 is greater than or equal to zero degrees, the wrist jaw operates in position mode. When commanded θ... 钳口 When 603 is less than zero degrees, the wrist jaws operate in force mode. θ 钳口 The error threshold is set to 5 degrees, and the minimum opening force threshold is set to 4.4 N.

[0079] Figure 8A The wrist jaws were shown operating in position mode from 49 to 60 seconds and from 62 to 67 seconds. The measured θ... 钳口 805 remains within a relatively narrow range, even when command θ 钳口 The 803 is configured such that the jaws are closed or open in position mode, presumably because the jaws, when open in position mode, encounter resistance or are restricted from fully opening to the command θ. 钳口 803. From 49 seconds to 52 seconds, 56 seconds to 59 seconds, and 62 seconds to 66 seconds, when the jaws are open or held in position mode at the same θ. 钳口 When, θ 钳口 Error (larger command θ) 钳口 803 with a smaller measured θ 钳口 The difference between 805 and 05 can be greater than 5 degrees of θ. 钳口 Error threshold.

[0080] During position mode, the command clamping force 807 can be set to a default value of zero N by the clamping force controller. Even during force mode, the command clamping force 807 is still set to zero N. Positive values ​​of the measured opening force 809 correspond to the jaw opening force in position mode, while negative values ​​correspond to the clamping force in force mode when the jaws are closed. The measured opening force 809 in position mode typically follows the command θ. 钳口 The profile of 803, because the jaws move from open to command θ. 钳口 803 is constrained. The result is that when command θ... 钳口 When 803 is increased to open the jaws wider, the measured opening force 809 is stronger; conversely, when command θ is increased... 钳口 When 803 is reduced to open the jaws more narrowly, the measured opening force 809 is weaker. Because the feedback control loop is not enabled to keep the measured opening force 809 above the minimum opening force threshold of 4.4N between 53 and 60 seconds, the measured opening force 809 may drop below the minimum opening force threshold.

[0081] Figure 8B This illustrates, according to various aspects of the subject matter, that when the control system maintains the measured opening force 819 above a pre-specified minimum opening force threshold 817 during jaw opening in position mode, the wrist jaw command θ... 钳口 813. Measured θ 钳口 815. Time curve of commanded clamping force 817 and measured opening force 819. θ 钳口 The error threshold was set again to 5 degrees, and the minimum opening force threshold was set to 4.4 N.

[0082] exist Figure 8B In the middle, when the minimum jaw opening force is not maintained, command θ 钳口 813 and the measured θ 钳口 815 time curve and Figure 8A command θ 钳口 803 and the measured θ 钳口 805 is largely the same. During position mode, the command clamping force 817 is reset to the default value of zero N by the clamping force controller. However, when θ 钳口 Error (larger command θ) 钳口 813 with a smaller measured θ 钳口 The difference between 8 and 15) is greater than 5 degrees for θ. 钳口 At the error threshold, during the position mode between 30 and 43 seconds, the measured opening force 819 is maintained by the feedback control loop and the clamping force controller at or above the minimum opening force threshold of 4.4N. Specifically, when the jaws are opening and maintaining the same θ... 钳口Alternatively, even when closing in position mode, maintain the minimum measured opening force 819. Note that when the measured opening force 819 may be negative, the minimum opening force threshold in position mode has no effect on force mode.

[0083] Figure 9 This is a flowchart illustrating a method 900 for feedback control of a surgical robotic system according to various aspects of the subject matter. This method maintains the opening force of the wrist jaws above a pre-specified minimum jaw opening force threshold during jaw opening in a position mode by analyzing the desired jaw angle, the estimated jaw angle, and the measured opening force. Method 900 can be derived from... Figure 5 The control system is implemented by controller 562, which receives the desired θ from user input. 钳口 θ, estimated or measured 钳口 It also receives the measured opening force from the sensor and estimator 566 to generate actuator position commands for driving the wrist jaws.

[0084] In block 901, method 900 determines whether the wrist jaws are in a position mode. In one implementation, block 901 may determine the desired θ. 钳口 Is it greater than or equal to the threshold θ between the position mode and the force mode? 钳口 The process continues for more than a pre-specified period of time to confirm that the wrist jaws are in position mode. In one implementation, a threshold θ is used. 钳口 It can be set to zero. If the wrist jaws are not in position mode, the wrist jaws are in force mode and the minimum opening force is not enabled. In block 909, method 900 generates an actuator position command without maintaining the minimum opening force. In one embodiment, in addition to generating the actuator position command, block 909 will also expect θ 钳口 Convert into a desired clamping force command to achieve the desired clamping force or opening force.

[0085] If the jaws are in position mode, then box 903 determines θ 钳口 Error (this error is the expected θ) 钳口 With the estimated or measured θ 钳口 Is the difference between them greater than or equal to θ? 钳口 An error threshold is used to determine whether the jaws are prevented from opening to the desired θ. 钳口 In one implementation, box 903 may employ stabilization technology to determine the desired θ. 钳口 Is it greater than the estimated θ? 钳口 and θ 钳口 Is the error greater than or equal to θ? 钳口 The error threshold persists for a pre-specified duration. In one implementation, block 903 can be determined by separately determining the desired θ. 钳口The jaws are being increased, kept the same, or decreased to detect whether they are opening or remaining static. 钳口 Or closed. If θ 钳口 Error less than θ 钳口 If the error threshold is set, then method 900 defaults to box 909 to generate actuator position commands without maintaining a minimum opening force.

[0086] If the jaws are in position mode, θ 钳口 Error greater than or equal to θ 钳口 If an error threshold is set, block 905 determines whether the measured opening force is lower than a pre-specified minimum jaw opening force threshold. In one embodiment, block 905 may employ anti-jitter technology to determine whether the measured opening force is less than the minimum jaw opening force threshold plus a margin that spans anywhere within a window equal to the number of samples from the jaw opening force counter. In one embodiment, the measured opening force can be... Figure 5 The feedback control system is sampled at loop cycle time. The jaw opening force counter can be incremented by one for each control loop cycle, during which the measured opening force is greater than the minimum jaw opening force threshold plus a margin. The jaw opening force counter can be reset when the measured opening force is less than the minimum jaw opening force threshold. The measured opening force is considered to be below the minimum jaw opening force threshold for the entire window as long as the measured opening force is less than the minimum jaw opening force threshold plus a margin spanning any point within a window equal to the number of samples in the jaw opening force counter. Otherwise, the measured opening force is greater than or equal to the minimum jaw opening force threshold, and method 900 defaults to block 909 to generate an actuator position command without maintaining the minimum opening force.

[0087] If the opening force measured when the jaws are in position mode is less than the minimum jaw opening force threshold and θ 钳口 Error greater than or equal to θ 钳口 If an error threshold is reached, block 907 generates a compensated actuator position command to maintain the measured opening force above a minimum jaw opening force threshold. In one embodiment, block 907 may calculate a jaw opening force error, which is the difference between the minimum jaw opening force threshold and the measured opening force. A zero-steady-state controller (such as a proportional-integral (PI) force controller) may be deployed to receive the jaw opening force error, thereby maintaining the measured opening force at or above the minimum jaw opening force threshold. The output of the PI force controller may be combined with the output of an inverse kinematics matrix that operates on errors in the desired position and orientation of the wrist jaws to generate a compensated actuator position command. The compensated actuator position command is added to an existing actuator position command to drive the wrist jaws, thereby maintaining a minimum amount of opening force when the jaws are open in position mode.

[0088] On another front, controller 562 can adjust the commanded clamping force to smooth the clamping force applied when the wrist jaws transition between position and force modes. Smoothing the clamping force applied during mode transitions minimizes undesirable abrupt changes in clamping force caused by positional changes and the commanded clamping force of the jaws, which could cause the jaws to accidentally drop the grasped object when the jaws cross the discontinuity between the two modes. During position mode, θ is expected to... 钳口 Greater than or equal to the braking threshold. The position controller can determine the desired θ. 钳口 and expected θ 俯仰 and expected θ 偏转 This is converted into a corresponding actuator position command to drive the wrist jaws to the desired position and orientation. During force mode, when the desired θ... 钳口 When the value is below the braking threshold, for example when the desired θ 钳口 When the braking force is set to zero degrees and is negative, the clamping force controller can be enabled to apply the desired θ. 钳口 Interpreted as a clamping force command and can express the desired θ 钳口 This is converted into a compensating current, which can be added to the current used for existing position commands to drive the wrist jaws to achieve commanded gripping force.

[0089] In one implementation, to smooth the clamping force applied during mode transitions, the feedback control system can employ anti-shake technology when the braking is set to zero degrees. When the desired θ 钳口 When oscillating near positive and negative values, the anti-shake technology can prevent the clamping force controller from being repeatedly enabled and disabled, thereby generating oscillations in the commanded clamping force.

[0090] In one implementation scheme, the feedback control system can analyze the desired θ 钳口 The system uses a combination of commanded and measured clamping forces to minimize abrupt changes in clamping force when the wrist jaws transition from position mode to force mode. The feedback control system can determine whether the commanded clamping force is due to a sudden change in clamping force as desired by θ. 钳口 The system adjusts the clamping force by decreasing it below the braking threshold indicated by the activated clamping force controller, and by checking whether the error between the measured clamping force and the commanded clamping force exceeds a pre-specified maximum force error. If so, the feedback control system can set the commanded clamping force to the measured clamping force minus a pre-specified margin when the wrist jaws transition from position mode to force mode.

[0091] In one implementation scheme, the feedback control system can analyze the desired θ 钳口 The system uses a combination of commanded and measured clamping forces to minimize abrupt changes in clamping force when the wrist jaws transition from force mode to position mode. The feedback control system can determine whether the commanded clamping force is less than a pre-specified minimum clamping force value, and whether the commanded clamping force is due to factors such as the desired θ.钳口 The system checks whether the clamping force is increased above the braking threshold and then reduced by the controller, and whether the absolute value of the error between the measured clamping force and the minimum clamping force is less than a pre-specified maximum clamping force error value. If so, the feedback control system can set the command clamping force to the pre-specified minimum clamping force value when the wrist jaws switch from force mode to position mode.

[0092] Figure 10 This is a block diagram of an exemplary control system 1000 according to various aspects of the subject matter, which controls the position and clamping force of an end effector of a robotic surgical tool when the end effector is in a position mode or a force mode, or when the end effector transitions between a position mode and a force mode. In one embodiment, the end effector includes a wrist jaw. The robot control system 1000 includes an input processing unit 502, an actuator command generator 504, a position controller 506, a clamping force controller 508, a device including one or more actuator units 510 and / or cables and wrist links 512, a relaxation controller 514, a position estimator 522, and a clamping force estimator 524.

[0093] The input processing unit 502 and the actuator command generator 504 receive the desired angular position of the wrist jaws and convert the desired angular position into a corresponding actuator position command (via an inverse kinematics algorithm). This actuator position command is output to the position controller 506 and / or the clamping force controller 508. For example, the input desired angular position may include a desired θ. 钳口 Expected θ 俯仰 and expected θ 偏转 When the expected θ 钳口 When the braking threshold is greater than or equal to the expected θ 钳口 This can be considered a position command. When θ is expected... 钳口 When the value is less than the braking threshold, the expected θ 钳口 The clamping force controller 508 can convert the desired clamping force command (e.g., command clamping force) into a current command to achieve the desired clamping force.

[0094] Position controller 506 can receive position feedback from position and / or velocity sensors on actuator unit 510. Due to the kinematic relationship between the actuator and the wrist jaws, achieving the desired actuator position can, in turn, yield the desired position of the wrist jaws. Since actuator unit 510 is connected to the robot wrist via an elastic cable (or line) that can change length under force, estimations based solely on the pure kinematic relationship between actuator position and wrist movement may be inaccurate. By incorporating cable elasticity into the estimation algorithm (e.g., using a Kalman filter), position estimator 522 can provide a more accurate estimate of the wrist engagement position and velocity to actuator command generator 504 and clamping force estimator 524. The estimated position and velocity information can then be used for precise wrist positioning and estimation of frictional forces.

[0095] In one embodiment, the clamping force controller 508 receives feedback on the cable tension measured by a force sensor or torque sensor on the cable conductor. The clamping force estimator 524 then uses an algorithm to estimate the clamping force between the jaws based on the tension value measured on the cable. The clamping force controller 508 can compare the estimate with the desired clamping force and generate an additional current command to achieve the desired clamping force. The wrist jaws can be coupled to a tool drive via four independent cables, each actuated by an independent motor. In one embodiment, the motors can be driven by current. The current command can include two parts: a first part of the driving current can come from the position controller 506, and a second part from the clamping force controller 508. These two current commands can be summed and sent to the actuator unit 510.

[0096] The slack controller 514 performs the task of ensuring that the tension on the cable never drops below zero (or a predetermined positive value to compensate for slack). The cable is the only tension-bearing component of the end effector; negative forces cannot be applied to it. Therefore, it is desirable to prevent the tension on the cable from dropping to zero. To achieve this, the slack controller 514 can monitor the force values ​​from force sensors on the cable and compare the minimum of these force values ​​with a predetermined threshold. If the minimum force value across all cables drops below the threshold, the slack controller 514 can generate additional position commands to all actuators to ensure that the desired minimum tension is maintained.

[0097] To ensure a smooth application of the clamping force during mode transitions, the input processing unit 502 can employ anti-shake technology when the brake is set to zero degrees. Anti-shake technology allows the clamping force controller 508 to determine the desired θ before transitioning the wrist jaws from position mode to force mode. 钳口 Whether it is less than the minimum pre-specified duration of the braking threshold. When transitioning from force mode to position mode, as long as θ is expected... 钳口If the force is greater than or equal to the braking threshold, the input processing unit 502 can disable the clamping controller 508. Therefore, the anti-shake technology can be unilateral. The anti-shake technology prevents the clamping force controller 508 from being repeatedly enabled and disabled, which is when the desired θ 钳口 Oscillations near the brake may cause oscillations in the command clamping force.

[0098] Figure 11A This shows the command θ when there is no stabilization algorithm. 钳口 1103 is set to the command θ of the wrist jaws when near a threshold. 钳口 1103. Measured θ 钳口 1105, commanded clamping force 1107, measured clamping force 1109, and force from a clamping force controller (e.g., Figure 10 The time curve of the current command 1106 of the clamping force controller 508 is shown. The braking threshold is set to zero, so that when command θ 钳口 When 1103 is greater than or equal to zero degrees, the wrist jaws operate in position mode. When the command θ... 钳口 When 1103 is less than zero, the wrist jaws operate in force mode. Positive clamping force indicates the clamping force in force mode, and negative clamping force indicates the clamping force in position mode.

[0099] Figure 11A The image shows the wrist jaws operating in position mode between 11.6 and 12 seconds. After 12 seconds, the command θ is issued because the user input device (UID) is set to the brake position. 钳口 1103 was set near the braking threshold. The measured θ 钳口 1105 remains above approximately 20 degrees, presumably because the jaws are gripping the object. As the wrist jaws switch between position and force modes, the clamping force controller 508 is repeatedly enabled and disabled, causing oscillations in the commanded clamping force 1107 and current command 1106 from the clamping force controller 508 when it is enabled during force mode. This results in an undesirable large oscillation of the measured clamping force 1109 observed between 12 and 12.4 seconds. The measured θ... 钳口 1105 also demonstrates some undesirable oscillations caused by the swing of the measured clamping force 1109.

[0100] Figure 11B This illustrates various aspects of the control system (e.g., based on the technology of this subject) Figure 10 The input processing unit 502 and the actuator command generator 504) will send the command θ 钳口 When setting 1113 to use the anti-shake algorithm near a threshold, the wrist jaw command θ 钳口 1113. Measured θ 钳口1115. Time curves of commanded clamping force 1117, measured clamping force 1119, and current command 1116 from clamping force controller 508. The braking threshold is set to zero again. Between 30.2 and 30.9 seconds, the wrist jaws operate in position mode. After 30.9 seconds, command θ... 钳口 1113 is set near the braking threshold.

[0101] Only when the expectation θ 钳口 The anti-shake algorithm only enables the clamping force controller 508 to switch the wrist jaws from position mode to force mode when the temperature remains below zero for a pre-specified minimum duration. Because the control system does not detect this situation, the wrist jaws remain in position mode and the clamping force controller 508 is not enabled. As a result, the commanded clamping force 1117 remains at its default value of 0N, and the current command 1116 from the clamping force controller 508 also remains at 0. The measured clamping force 1119 does not exhibit large oscillations, and the measured θ... 钳口 1115 did not show Figure 11A The oscillations observed in the data ensured a smooth application of the clamping force (the measured clamping force 1119 was shown as positive, even when the wrist jaws remained in position mode).

[0102] When the wrist jaws are gripping an object while transitioning between position and force modes, the smooth application of the gripping force can become important. For example, during position mode, even if the gripping force controller 508 is not enabled, a non-zero measured gripping force may still exist if the wrist jaws are gripping an object. When the desired θ 钳口 When the clamping force drops below the braking threshold, indicating a transition from position mode to force mode, the clamping force controller 508 can initially drive the command clamping force from 0N. Similarly, when transitioning from force mode to position mode, if the clamping force controller 508 is disabled, the command clamping force can be reset to the default value of 0N output from the position controller 506. As a result, the clamping force measured during the transition may change abruptly, potentially causing the object to fall from the wrist jaws.

[0103] Figure 12A This illustrates the wrist jaw command θ when the jaws transition from position mode to force mode and back to position mode, and the control system does not attempt to limit the variation of the measured clamping force 1209. 钳口 1203. Measured θ 钳口 1205. Time curves of commanded clamping force 1207 and measured clamping force 1209. The braking threshold is set to 0 again, so that when command θ... 钳口 When 1203 is greater than or equal to 0 degrees, the wrist jaws operate in position mode. When the command θ... 钳口When 1203 is less than 0 degrees, the wrist jaws operate in force mode.

[0104] The wrist jaws initially operate in position mode. Command θ 钳口 1203 was initially set to 0 degrees and the clamping force 1207 was initially set to 0 N. The measured θ... 钳口 1205 is at 25 degrees, and the measured clamping force 1209 is 8 N due to the object being gripped between the jaws. At time 27.5 seconds, command θ is given. 钳口 1203 becomes negative to switch the wrist jaws from position mode to force mode. When the clamping force controller 508 is enabled, the command clamping force 1207 increases gradually from 0N until the command θ. 钳口 1203 reaches its most negative value. However, the measured clamping force 1209 experiences a sudden drop of 5 N during the transition before the commanded ramp. At time 30 seconds, the command θ is... 钳口 1203 begins to become a smaller negative value. The commanded clamping force 1207 begins to decrease, and the measured clamping force 1209 follows suit as commanded. At time 31 seconds, the command θ... 钳口 1203 becomes positive to transition the wrist jaws from force mode back to position mode. When the clamping force controller 508 is disabled, the measured clamping force 1209 experiences a sudden jump with some overshoot from 0N to a resting 8N in position mode. It is desirable to minimize the sudden change in the measured clamping force 1209 during the transition.

[0105] In one implementation, to minimize abrupt changes in the gripping force of the wrist jaws when grasping an object during the transition from position mode to force mode, the gripping force controller 508 can adjust the command gripping force. For example, when commanding θ 钳口 When the clamping force becomes less than the braking threshold and is activated under certain conditions, the clamping force controller 508 can set the command clamping force to the currently measured clamping force minus a pre-specified margin. This prevents the measured clamping force from dropping to near-zero N during transitions, thereby reducing the likelihood of the jaws causing the object gripped between them to fall. In one embodiment, the measured clamping force can be generated by the clamping force estimator 524 based on the tension value measured on the cable from the cable and wrist link 512.

[0106] To assess the first condition for adjusting the command clamping force, the clamping force controller 508 can determine whether the command clamping force is currently or will be reduced due to a decrease in the command θ below the braking threshold. 钳口The clamping force is increased as indicated. For the second condition, the clamping force controller 508 can determine whether the error between the measured clamping force and the commanded clamping force is greater than a pre-specified maximum force error. In one embodiment, the clamping force controller 528 can use anti-shake technology for one or both of these conditions. If both conditions are met, the clamping force controller 508 can set the commanded clamping force to the currently measured clamping force minus a pre-specified margin.

[0107] In one implementation, to minimize abrupt changes in the gripping force of the wrist jaws when grasping an object during the transition from force mode to position mode, the gripping force controller 508 can adjust the command gripping force. For example, when commanding θ 钳口 When the force becomes greater than the braking threshold and the clamping force controller 508 is disabled under certain conditions, the clamping force controller 508 can set the command clamping force to a pre-specified minimum clamping force value. Doing so, instead of starting from the default ON of the position mode, reduces the variation in the measured clamping force as it rises to the static clamping force of the position mode.

[0108] To evaluate the conditions used to adjust the clamping force, the clamping force controller 508 can determine whether the commanded clamping force is less than a pre-specified minimum clamping force value. The clamping force controller 508 can also determine whether the commanded clamping force is being adjusted as specified by command θ. 钳口 The clamping force decreases as indicated by the direction or exceeding the braking threshold. The clamping force controller 508 can further determine whether the absolute value of the error between the measured clamping force and the minimum clamping force value is less than a pre-specified maximum clamping force error value. In one embodiment, the clamping force controller 528 may use anti-shake technology for one or more of these conditions. If all conditions are met, the clamping force controller 508 can set the command clamping force to the pre-specified minimum clamping force value. In one embodiment, the pre-specified minimum clamping force value may be set to 3N.

[0109] Figure 12B This illustrates, according to various aspects of the subject matter, the command θ of the wrist jaws when the control system limits the variation of the measured clamping force 1219 as the jaws switch between position and force modes. 钳口 1213. Measured θ 钳口 1215. Time curves of commanded clamping force 1217 and measured clamping force 1219. The braking threshold is set to 0 again, so that when command θ... 钳口 When 1213 is greater than or equal to 0 degrees, the wrist jaws operate in position mode. When the command θ... 钳口When 1213 is less than 0 degrees, the wrist jaws operate in force mode. The absolute value of the error between the measured clamping force and the commanded clamping force is set to be greater than 8N, which is the maximum pre-specified clamping force error value. The minimum pre-specified clamping force value is set to 3N.

[0110] The wrist jaws initially operate in position mode, command θ 钳口 1213. Measured θ 钳口 1215, the initial state of the commanded clamping force 1217 and the measured clamping force 1219 and Figure 12A The same applies. At time 37.4 seconds, command θ... 钳口 1203 becomes negative to switch the wrist jaws from position mode to force mode. However, the command clamping force 1217 starts at approximately 6.2 N instead of 0 N in force mode; this 6.2 N is obtained by subtracting a pre-specified margin from the measured clamping force 1219 at this point. Because the absolute value of the error between the measured clamping force 1219 and the command clamping force 1217 is less than the pre-specified maximum force error, the condition for adjusting the command clamping force 1217 is met. As a result, during the transition from position mode to force mode, the measured clamping force 1219 experiences a significantly smaller decrease than without adjustment of the command clamping force 1217. The command clamping force 1217 remains at 6.2 N until it is gradually negative by the command θ. 钳口 The clamping force 1217 determined by command 1213 becomes greater than 6.2N.

[0111] At time 39.8 seconds, command θ 钳口 1213 begins to change to a smaller negative value. The commanded clamping force 1217 begins to decrease, and the measured clamping force 1219 follows suit as commanded. At time 40.5 seconds, the commanded clamping force 1217 remains at the pre-specified minimum clamping force value of 3N, instead of continuing to decrease to 0N, which would otherwise occur at command θ. 钳口 This occurs when 1213 becomes positive to switch the wrist jaws from force mode to position mode without adjustment. Because the measured clamping force 1219 is less than the pre-specified minimum clamping force value of 3N, and the absolute value of the error between the measured clamping force 1219 and the command clamping force 1217 is less than the pre-specified maximum force error, the conditions for adjusting the command clamping force 1217 are met. As a result, when the measured clamping force 1219 jumps to the stationary position mode of 8N during the transition, the measured clamping force 1219 experiences a significantly smaller change than it would without adjustment of the command clamping force 1217. The command clamping force 1217 remains at 3N until command θ... 钳口 The clamping force determined by command 1213 becomes 0N in 1217.

[0112] Figure 13 This is a flowchart illustrating a method 1300 for feedback control of a surgical robot system according to various aspects of the subject matter, the method being used to set a desired θ of the wrist jaws near a braking threshold. 钳口 An anti-shake algorithm is employed, or it is used to limit changes in the measured clamping force when the wrist jaws transition between position and force modes. Method 1300 can be derived from... Figure 5 The controller of the control system is 562 or Figure 10 The clamping force controller 508 of the control system is implemented, and the controller or the clamping force controller receives the desired θ from the user input. 钳口 and from Figure 5 Sensors and estimators 566 or Figure 10 The clamping force estimator 524 measures the clamping force to generate a command clamping force for driving the wrist jaws.

[0113] Starting with the position pattern in box 1301, method 1300 determines the desired θ in box 1303. 钳口 Whether the braking threshold is less than the minimum duration. In one implementation, the minimum duration can be pre-specified or configurable. Block 1303 implements a debounce algorithm to prevent repeated enabling and disabling of the force mode, which is when the desired θ 钳口 Conditions that may cause oscillations in the command clamping force when set near a braking threshold. In one embodiment, block 1303 can determine whether the command clamping force is currently or will be as desired by θ. 钳口 It decreases to below the braking threshold indicated by the increase. If the desired θ 钳口 If the braking threshold is maintained for a minimum duration specified in advance, the wrist jaws remain in position mode of box 1301.

[0114] Otherwise, if the expected θ 钳口 If the braking threshold is maintained for a pre-specified minimum duration, the wrist jaws are transitioning from position mode to force mode. Box 1304 determines whether the command clamping force is increasing. If this condition is false, box 1307 sets the command clamping force from the desired θ. 钳口 The mode switch is performed without adjusting the command clamping force, thus limiting the variation in the measured clamping force during the mode switch. Otherwise, if the condition in block 1304 is true, block 1305 determines whether the error between the measured clamping force and the command clamping force is greater than the maximum force error during the mode switch. In the position mode prior to the mode switch, the command clamping force can be the default 0N. The measured clamping force may differ from the command clamping force prior to the mode switch because the wrist jaws may be gripping an object. In one embodiment, the maximum force error may be pre-specified or configurable.

[0115] If the condition in box 1305 is true, then box 1309 sets the command clamping force to the measured clamping force minus the margin when the wrist jaws transition from position mode to force mode. In one embodiment, the margin may be pre-specified or configurable. Otherwise, if the condition in box 1305 is false, then box 1307 sets the command clamping force to the desired θ. 钳口 The mode is switched, and the command clamping force is not adjusted, thus limiting the measured change in clamping force during mode transition.

[0116] When the wrist jaws are in force mode in box 1311, method 1300 determines the desired θ in box 1313. 钳口 Whether it is greater than or equal to the braking threshold. In one embodiment, block 1311 can determine whether the commanded clamping force is as expected by θ. 钳口 It decreases in the direction indicated by the increase in the braking threshold, and θ is expected to decrease. 钳口 Just below the braking threshold. If the desired θ 钳口 If the braking threshold is not greater than or equal to the braking threshold, the wrist jaws remain in the force mode of frame 1311.

[0117] Otherwise, if the expected θ 钳口 If the force is greater than or equal to the braking threshold, the wrist jaws are transitioning from force mode to position mode. Box 1315 determines whether the command clamping force is decreasing and whether the command clamping force is less than the minimum clamping force during the mode transition. In one embodiment, the minimum clamping force may be pre-specified or configurable. If the command clamping force is not decreasing or if the command clamping force is not less than the minimum clamping force during the mode transition, box 1307 sets the command clamping force from the desired θ. 钳口 The mode is switched, and the command clamping force is not adjusted, thus limiting the measured change in clamping force during mode transition.

[0118] Otherwise, if the commanded clamping force is decreasing and if the commanded clamping force is less than the minimum clamping force during the mode transition, block 1317 determines whether the absolute value of the error between the measured clamping force and the minimum clamping force value is less than the maximum force error during the mode transition. In one embodiment, the maximum force error may be pre-specified or configurable. The maximum force error in block 1317 for force-to-position mode transition may be the same as or different from the maximum force error in block 1305 for position-to-force mode transition.

[0119] If the condition in box 1317 is true, then box 1319 sets the command clamping force to the minimum clamping force when the wrist jaws transition from force mode to position mode. Otherwise, if the condition in box 1317 is false, then box 1307 sets the command clamping force to the minimum clamping force from the desired θ. 钳口The mode is switched, and the command clamping force is not adjusted, thus limiting the measured change in clamping force during mode transition.

[0120] Figure 14 This is a block diagram illustrating exemplary hardware components of a surgical robot system according to various aspects of the subject matter. The surgical robot system may include an interface device 50, a surgical robot 80, and a control tower 70. The surgical robot system may include other hardware components or additional hardware components; therefore, this diagram is provided by way of example and not as a limitation on the system architecture.

[0121] The interface device 50 includes a camera 51, a sensor 52, a display 53, a user command interface 54, a processor 55, a memory 56, and a network interface 57. The camera 51 and sensor 52 can be configured to capture color and depth image information of the surgical robot system. The images captured by the camera 51 and sensor 52 can be projected onto the display 53. The processor 55 can be configured to run an operating system to control the operation of the interface device 50. The memory 56 can store image processing algorithms, the operating system, program code, and other data used by the processor 55. The interface device 50 can be used to generate the desired θ of the wrist jaw under the control of a remote operator. 俯仰 θ 偏转 and θ 钳口 .

[0122] User command interface 54 may include interfaces for other features such as a web portal. Hardware components may communicate via a bus. The interface device may communicate with the surgical robot system via an external interface using network interface 57. The external interface may be wireless or wired.

[0123] The control tower 70 may be a mobile field care cart housing a touchscreen display, a computer controlling the surgeon's robotic manipulation of instruments, a safety system, a graphical user interface (GUI), a light source, and a video and graphics computer. The control tower 70 may include a central computer 71 (which may include at least a visualization computer, a control computer, and an auxiliary computer), various displays 73 (which may include team displays and nurse displays), and a network interface 78 coupling the control tower 70 to both the interface device 50 and the surgical robot 80. The control tower 70 may also accommodate third-party devices such as an advanced light engine 72, an electrosurgical generator (ESU) device 74, and inhalers and CO2 canisters 75. The control tower 70 may provide additional features for user convenience, such as a nurse-display touchscreen, soft power and E-hold buttons, a user-facing USB for video and still images, and an electronic caster control interface. The auxiliary computer may also run real-time Linux, providing logging / monitoring and interaction with cloud-based web services. The central computer 71 of the control tower 70 may receive the desired θ of the wrist jaws generated by the interface device 50.俯仰 θ 偏转 and θ 钳口 To achieve the method described herein for controlling the clamping or opening force of the jaws.

[0124] The surgical robot 80 includes an articulated operating table 84 with multiple integrated arms 82 positioned above the target patient anatomy. A set of compatible tools 83 can be attached to / detached from the distal ends of the arms 82, enabling the surgeon to perform various surgical procedures. The surgical robot 80 may also include a control interface 85 for manually controlling the arms 82, the operating table 84, and the tools 83. The control interface 85 may include items such as, but not limited to, remote controls, buttons, panels, and touchscreens. Other accessories such as cannulas (cannulas, sealing cartridges, and tamponades) and drapes can also be manipulated to perform surgery using the system. In one embodiment, the multiple arms 82 may include four arms mounted on both sides of the operating table 84, with two arms on each side. For a particular surgical procedure, an arm mounted on one side of the operating table 84 can be positioned on the other side of the operating table 84 by stretching and crossing under the operating table 84 and the arm mounted on the other side, resulting in a total of three arms positioned on the same side of the operating table 84. The surgical instrument may also include a computer 81 and a network interface 88, which allows the surgical robot 80 to be positioned to communicate with the control tower 70.

[0125] For purposes of explanation, the foregoing description uses specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that specific details are not required to practice the invention. The foregoing description of specific embodiments of the invention has been provided for illustrative and descriptive purposes. These are not intended to be exhaustive or to limit the invention to the specific forms disclosed; various modifications and alterations can be made to this disclosure in light of the foregoing teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application. Therefore, these embodiments enable others skilled in the art to best utilize the invention, as well as various embodiments with modifications suitable for the contemplated particular uses. The following claims and their equivalents are intended to define the scope of the invention.

[0126] The methods, devices, processes, and logic components described above can be implemented in a variety of different ways and in a variety of different combinations of hardware and software. Controllers and estimators may include electronic circuitry. For example, all or part of an implementation may be a circuit including an instruction processor, such as a central processing unit (CPU), microcontroller, or microprocessor; an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a field-programmable gate array (FPGA); or a circuit including discrete logic components or other circuit components (including analog circuit components, digital circuit components, or both); or any combination thereof. As an example, the circuit may include discretely interconnected hardware components and / or may be combined on a single integrated circuit die, distributed among multiple integrated circuit dies, or implemented in a multi-chip module (MCM) of multiple integrated circuit dies in a co-package.

[0127] The circuit may also include or access instructions that are executed by the circuit. These instructions may be stored in a tangible storage medium other than transient signals, such as flash memory, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM); or on a magnetic disk or optical disk, such as an optical disc read-only memory (CDROM), a hard disk drive (HDD), or other magnetic disk or optical disk; or in or on another machine-readable medium. A product (such as a computer program product) may include a storage medium and instructions stored in or on that medium, and these instructions, when executed by circuitry in the device, may cause the device to perform any of the processes described above or shown in the accompanying drawings.

[0128] These implementations can be distributed as circuits among multiple system components, such as among multiple processors and memories, optionally including multiple distributed processing systems. Parameters, databases, and other data structures can be stored and managed separately, or combined into a single memory or database. They can be organized logically and physically in a variety of different ways and implemented in a variety of different ways, including as data structures such as linked lists, hash tables, arrays, records, objects, or implicit storage mechanisms. Programs can be parts of a single program (e.g., subroutines), stand-alone programs, distributed across multiple memories and processors, or implemented in a variety of different ways, such as in libraries, such as shared libraries (e.g., dynamic link libraries (DLLs)). For example, when executed by the circuit, the DLL can store instructions for performing any of the processes described above or shown in the figures.

[0129] Furthermore, the various controllers discussed herein may take the form of, for example, processing circuitry, microprocessors or processors, and computer-readable media storing computer-readable program code (e.g., firmware) executable by the (micro)processor, logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers. Controllers may be configured with hardware and / or firmware to perform the various functions described below and shown in the flowcharts. Additionally, some components shown as being internal to the controller may also be stored externally, and other components may be used.

Claims

1. A method for controlling the clamping force generated by the jaws of a gripping tool from a surgical robotic system, the jaws being configured to hold a cutting instrument, the method comprising: The processor determines whether the jaws are closed in a position mode based on the input jaw angle between the jaws, the position mode being characterized by using a position command to position the jaws at the input jaw angle; Measure the clamping force between the jaws in the position mode; The processor determines whether the measured clamping force exceeds the clamping force threshold in the position mode; The processor generates a clamping force error in response to determining that the measured clamping force exceeds the clamping force threshold, wherein the clamping force error includes the difference between the measured clamping force and the clamping force threshold; An updated position command is generated based on the clamping force error; and The updated position command is applied to position the jaws, which limits the clamping force to the clamping force threshold.

2. The method of claim 1, wherein determining that the jaws are closed in the position mode comprises: The processor determines that the input jaw angle is greater than or equal to a threshold jaw angle for a period of time exceeding a minimum, wherein the threshold jaw angle includes the jaw angle when the jaws simultaneously contact an object held between the jaws or when the jaws begin to contact each other without being held by an object.

3. The method of claim 1, wherein determining that the jaws are closed in the position mode comprises: The processor determines that the input jaw angle is decreasing for a minimum duration in the position mode.

4. The method according to claim 1, wherein determining whether the measured clamping force exceeds the clamping force threshold comprises: The processor determines that the measured clamping force exceeds the clamping force threshold if the measured clamping force exceeds the clamping force threshold minus any margin within the time window.

5. The method of claim 4, wherein the length of the time window is measured by a clamping force counter, wherein the operation of the clamping force counter includes: Whenever the measured clamping force is sampled, the clamping force counter is incremented by one when the measured clamping force is less than the clamping force threshold minus the margin; as well as When the measured clamping force is greater than the clamping force threshold, the clamping force counter is reset.

6. The method of claim 5, wherein determining whether the measured clamping force exceeds the clamping force threshold further comprises: When the measured clamping force exceeds the clamping force threshold minus the margin at any point within the time window, the processor determines that the measured clamping force exceeding the clamping force threshold is continuously equal to the entire length of the time window of the clamping force counter.

7. The method of claim 1, wherein generating the updated location command comprises: The processor generates a compensation position command based on the clamping force error; as well as The processor combines the compensated position command and the position command to generate the updated position command.

8. A device for controlling the jaws of a gripping tool in a surgical robot system, comprising: A sensor configured to estimate the clamping force generated by the jaws to generate a measured clamping force; Processor, the processor being configured to: The jaws are determined to be closed in a position mode based on the desired jaw angle between the jaws, the position mode being characterized by applying a position command to position the jaws at the desired jaw angle. Determine whether the measured clamping force exceeds a threshold in the position mode; and In response to determining that the measured clamping force exceeds the threshold, a clamping force error is generated to update the position command to limit the measured clamping force to the threshold; as well as An actuator driving unit is configured to apply an updated position command to drive the jaws to limit the measured clamping force to the threshold.

9. The apparatus of claim 8, wherein the processor is configured to determine that the jaws are closed in the position mode, comprising: Determine that the desired jaw angle is greater than or equal to a threshold jaw angle for a period of time exceeding a minimum, wherein the threshold jaw angle includes the jaw angle when the jaws are simultaneously in contact with an object held between the jaws or when the jaws begin to touch each other without being held by an object.

10. The apparatus of claim 8, wherein the processor is configured to determine that the jaws are closed in the position mode, comprising: Determine the minimum duration for which the desired jaw angle is decreasing in the position mode.

11. The apparatus of claim 8, wherein the processor is configured to determine whether the measured clamping force exceeds the threshold, comprising: The measured clamping force is determined to exceed the threshold if it exceeds the threshold minus any margin at any point within the time window.

12. The apparatus of claim 11, wherein the length of the time window is measured by a clamping force counter, wherein the clamping force counter is configured to: Whenever the sensor estimates the measured clamping force, the value is incremented by one if the measured clamping force is less than the threshold minus the margin; and When the measured clamping force is greater than the threshold, the clamping force counter is reset.

13. The apparatus of claim 12, wherein the processor is configured to determine whether the measured clamping force exceeds the threshold, further comprising: When the measured clamping force exceeds the threshold minus the margin at any point within the window, it is determined that the measured clamping force exceeding the threshold is continuously equal to the entire length of the time window of the clamping force counter.

14. The apparatus of claim 8, wherein the clamping force error includes the difference between the measured clamping force and the threshold.

15. The apparatus of claim 8, wherein the processor is configured to generate the clamping force error to update the position command, comprising: Generate a compensation position command based on the clamping force error; as well as The compensated position command and the position command are combined to generate the updated position command to limit the measured clamping force to the threshold.

16. A surgical robotic system, comprising: End effector, the end effector including a pair of jaws; A user interface device configured to generate an input jaw angle between the jaws; A processor, communicatively coupled to the end effector, is configured to: The jaws are determined to be closed in a position mode based on the input jaw angle between the jaws, the position mode being characterized by applying a position command to position the jaws at the input jaw angle; Measure the clamping force between the jaws in the position mode; Determine whether the measured clamping force exceeds a threshold in the position mode; In response to determining that the measured clamping force exceeds the threshold, a clamping force error is generated to update the position command to limit the measured clamping force to the threshold; as well as The updated position command is applied to position the jaws to limit the measured clamping force to the threshold.

17. The surgical robot system of claim 16, wherein the processor is configured to determine that the jaws are closing in the position mode, comprising: Determine that the input jaw angle is greater than or equal to a threshold jaw angle for a sustained period of time exceeding a first minimum time period, wherein the threshold jaw angle includes the jaw angle when the jaws simultaneously contact an object held between the jaws or when the jaws begin to contact each other without being held by an object. as well as It is determined that the input jaw angle is decreasing continuously for a second minimum time period in the position mode.

18. The surgical robot system of claim 16, wherein the processor is configured to determine whether the measured clamping force exceeds the threshold, comprising: The anti-shake algorithm is used to determine that the measured clamping force exceeds the threshold minus the margin.

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