Control of surgical instruments with recoil, friction, and compliance under external loads in a surgical robotic system

Abstract

To control surgical instruments in a surgical robotic system, multiple actuators establish static pretension by actuating in opposite directions during torque control. This static pretension reduces or eliminates compliance and elasticity, thereby reducing recoil width. To drive the tool, the actuators then move cooperatively to each other in position mode control, such that the movement maintains the static pretension while providing precise control.

Description

Technical Field

[0001] The implementation scheme involves using actuators in the surgical robotic arm of a surgical robotic system to control surgical robotic tools. Other implementation schemes are also described. Background Technology

[0002] Surgical robotic systems give operating surgeons the ability to mechanically perform one or more actions in a surgical procedure. In such systems, end effectors of surgical tools or instruments (such as suture devices, endoscopes, clamps, cutting tools, retractors, needles, energy emitters, etc.) are mechanically coupled to a robotic joint of the surgical robotic arm, such that movement or actuation of the robotic joint directly causes rotation, pivoting, or linear movement of the end effector (e.g., suturing with a suture device, rotation of an endoscope camera, pivoting of a gripper jaw, or translation of a needle). Once the tool is attached (e.g., contacts) to a tool actuator in the robotic arm, operator commands can cause movement and activate the functionality of the attached tool.

[0003] Besides recoil and internal friction, the drive mechanism between the tool driver and the tool's end effector can exhibit high compliance. Importantly, the end effector must precisely follow motion commands under varying external load conditions, such as loads resisting motion and loads assisting motion. In cases where two actuators are connected to control the end effector, the force or torque applied by one actuator may not reach the second actuator due to internal friction and compliance. Precise control with such recoil, friction, and compliance is challenging, especially when the drive mechanism is subjected to varying external loads. Summary of the Invention

[0004] By way of introduction, the preferred embodiments described below include methods, systems, instructions, and computer-readable media for controlling surgical instruments in a surgical robotic system. Multiple actuators establish static pretension by actuating in opposite directions to each other in torque control. This static pretension reduces or eliminates compliance and elasticity, thereby reducing recoil width. To drive the tool, the actuators then move cooperatively to each other in position mode control, such that the movement maintains the static pretension while providing precise control.

[0005] In a first aspect, a method for controlling a surgical instrument in a surgical robotic system is provided. A first link engaged with a first motor and a second link engaged with a second motor are actuated. The first and second links are mechanically coupled to an end effector of the surgical instrument. The first and second motors operate in opposite directions under torque control. When a threshold torque is reached due to actuation, control switches from torque control of the first and second motors to position control. The end effector is driven in the position control of the first and second motors. The first and second motors operate cooperatively with each other.

[0006] In a second aspect, a surgical robot system is provided. A surgical end effector is actuated by a first actuator and a second actuator via a transmission mechanism. A controller is configured to drive the first and second actuators in opposite directions to apply static pretension during the retraction of the first and second actuators, and to drive the first and second actuators in a coordinated manner to move the surgical end effector while maintaining the static pretension.

[0007] In a third aspect, a method for controlling a surgical tool in a surgical robotic system is provided. Variable recoil caused by the compliance of the engagement coupling between the actuator and the surgical tool is overcome, wherein the actuation of the actuator relative to the surgical tool is driven in opposite directions. The surgical tool is actuated by driving the actuator through the engagement coupling.

[0008] This invention is defined by the following claims, and the content of this section should not be construed as limiting those claims. Other aspects and advantages of the invention are discussed below in conjunction with preferred embodiments, and may subsequently be claimed independently or in combination. Attached Figure Description

[0009] Embodiments of the invention are illustrated by way of example and not by way of limitation in the accompanying drawings, wherein similar reference numerals indicate similar elements. It should be noted that references to "an" or "one" embodiment of the invention in this disclosure do not necessarily refer to the same embodiment, and that they refer to at least one. Furthermore, for the sake of brevity and to reduce the total number of drawings, a given drawing may be used to illustrate features of more than one embodiment of the invention, and not all elements in the drawing may be necessary for a given embodiment.

[0010] Figure 1 This is a drawn view of an exemplary surgical robotic system in a surgical setting;

[0011] Figure 2 This is a diagram of a system for engaging surgical tools with a tool actuator of a surgical robot arm;

[0012] Figure 3 This is a block diagram illustrating a surgical robot system for controlling surgical tools;

[0013] Figure 4 A lumped model is shown that uses multiple actuators to provide precise control of the end effector;

[0014] Figure 5 and Figure 6 This illustrates applying static pretension in different ways for position control. Figure 4 The lumped model; and

[0015] Figure 7 This is a flowchart of an implementation of a method for controlling surgical tools in a surgical robot system. Detailed Implementation

[0016] The control algorithm controls surgical instruments exhibiting joint recoil, friction, and compliance under external loads. Redundant actuators mechanically compensate for recoil and compliance. The control algorithm uses redundant actuators to generate static preload, such as by applying opposite biases from the two actuators during the return phase. This bias is maintained throughout operation, such as when the actuators are operated cooperatively while maintaining static preload.

[0017] Figures 1 to 3 Various aspects of the surgical robotic system are shown. Figure 1 An exemplary surgical robot system is shown. Figure 2 An exemplary connection between a surgical tool and a tool driver having a motor for actuating an end effector is shown. Figure 3 An exemplary control arrangement for actuating an end effector is shown. Other robot systems with different actuator and / or end effector arrangements can be used. Figures 4 to 6 An example of a lumped model is shown, which represents the generation of static pretension to reduce recoil and compliance. Figure 7 An embodiment of a method for controlling surgical instruments using static pretension is shown.

[0018] Figure 1 This is a drawing view of an exemplary surgical robotic system 1 in a surgical setting. The surgical robotic system 1 includes a user console 2, a control tower 3, and one or more surgical robotic arms 4 at a surgical platform 5 (e.g., a table, bed, etc.). The surgical robotic system 1 can be combined with any number of devices, tools, or accessories for performing surgery on a patient 6. For example, the surgical robotic system 1 may include one or more surgical tools 7 for performing surgical procedures. The surgical tool 7 may have an end effector at its distal end (which is also the distal end of the surgical robotic arm 4 to which the surgical tool 7 is attached) for performing surgical operations such as suturing, cutting, grasping, extending, or energy emission.

[0019] Each surgical tool 7 can be manually manipulated, robotically manipulated, or both during surgery. For example, a surgical tool 7 can be a tool for accessing, viewing, or manipulating the internal anatomy of a patient 6. In one embodiment, the surgical tool 7 is a suture device for suturing the patient's tissues. The surgical tool 7 can be directly and manually controlled by the hand of a bedside operator 8; or it can be robotically controlled by sending electronic commands to actuate the movement of the surgical robotic arm 4 to which the surgical tool 7 is attached. The surgical robotic arm 4 is shown as a tabletop system, but in other configurations, the surgical robotic arm 4 may be mounted on a trolley, ceiling, or sidewall, or in another suitable structural support.

[0020] Generally, a remote operator 9 (such as a surgeon) can use a user console 2 to remotely manipulate the surgical robot arm 4 and attached surgical instruments 7, for example, through remote operation. The user console 2 may be located in the same operating room as the rest of the surgical robot 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 different buildings, cities, or countries. The user console 2 may include a seat 10, foot controls 13, one or more handheld user interface devices (UIDs) 14, and at least one user display surgical instrument 15, which is configured to display a view of, for example, 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 surgical robotic arm 4 and the surgical instrument 7 (which is mounted on the distal end of the surgical arm 4).

[0021] In some variants, the bedside operator 9 can also operate the surgical robot system 1 in a "bedside" mode, where the bedside operator 8 (the user) is now positioned to one side of the patient 6 and simultaneously manipulates i) robot-driven tools (with end effectors) attached to the surgical robot arm 4, such as holding a handheld UID 14 with one hand, and ii) manual laparoscopic tools. For example, the bedside operator's left hand can manipulate the handheld UID to control the surgical robot components, while the bedside operator's right hand can manipulate the manual laparoscopic tools. Thus, in these variants, the bedside operator 8 can perform both robot-assisted minimally invasive surgery and manual laparoscopic surgery on the patient 6.

[0022] During the exemplary procedure (surgical operation), patient 6 is prepared for surgery and anesthetized by aseptically covering the patient with a sterile drape. Initial access to the surgical site can be manually performed (to facilitate access to the surgical site) while the arms of the surgical robot system 1 are in a retracted or withdrawn configuration. Once access is complete, initial positioning or preparation of the surgical robot system 1, including its surgical robot arm 4, can be performed. The surgery then continues, with the remote operator 9 at the 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 the surgical robot arm 4, such as tissue retraction, manual repositioning, and tool changes. Non-sterilized personnel may also be present to assist the remote operator 9 at the user console 2. When the procedure or surgery is completed, the surgical robot system 1 and the user console 2 can be configured or set to facilitate the input or printing of postoperative procedures (such as cleaning or disinfection) and health records via the user console 2.

[0023] 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 surgical robot system 1. UID 14 may be communicatively coupled to the rest of the surgical robot 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 surgical robot system 1 may use control signals derived from the spatial state signals to control the proportional movement of the actuator 17. In one embodiment, the 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 of the surgical robot 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.

[0024] The surgical robot system 1 may include a plurality of UIDs 14, wherein a corresponding control signal is generated for each UID 14 that controls the actuators and surgical instruments (end-effectors) of a respective surgical robot 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 surgical robot 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., in the surgical robot system 1. The surgical robot system 1 may include a right surgical robot arm 4 fixed to a bed or table on the right side of the patient, and a left surgical robot arm 4 located on the left side of the patient. The actuators 17 may include one or more motors, which are controlled such that they drive the joints of the surgical robot 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 surgical robot arm 4 may be controlled by spatial state signals generated from a particular UID 14. UID 14 can also control the movement of the corresponding surgical tool gripper. For example, each UID 14 can generate a corresponding clamping signal to control the movement of an actuator (e.g., a linear actuator) that opens or closes the jaws of the gripper at the distal end of the surgical tool 7 to grasp tissue within the patient 6. One or more UIDs in UID 14 can also control the movement of a suture device, such as activating the application of staples to the tissue of the patient 9.

[0025] In some respects, communication between the surgical platform 5 and the user console 2 can be achieved via a control tower 3, which translates user commands received from the user console 2 (and more specifically from the console computer system 16) into robot control commands transmitted to the surgical robotic arm 4 on the surgical platform 5. The control tower 3 can also transmit status and feedback from the surgical platform 5 back to the user console 2. The communication connection between the surgical platform 5, the user console 2, and the 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. The surgical robotic 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 or feeds 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.

[0026] Figure 2 A subsystem or part of the surgical robot system 1 is shown. This part is used to engage a surgical tool 240 with a tool actuator 230 of a surgical robot arm 220. The surgical robot arm 220 may be... Figure 1The surgical robotic arm 4 of the surgical robotic system 1 shown and discussed is a surgical robotic arm. The controller 210 may be, for example... Figure 1 It is part of the control tower 3 or user console 2.

[0027] Once the surgical instrument 240 engages with the tool actuator 230, the controller 210 can perform homing (e.g., identifying the position of the actuator relative to the surgical instrument to control the surgical instrument via the actuator). Homing may include adding static pretension to reduce compliance and recoil. Once the pretension is increased, the controller 210 operates the actuator of the tool actuator 230 to operate the end effector of the surgical instrument 240 while maintaining the static pretension.

[0028] Different surgical tools (e.g., surgical tool 240, and other detachable surgical tools - not shown) can be selectively attached (one at a time) to tool actuator 230. This can be accomplished by, for example, a human user holding the housing of surgical tool 240 in her hand and moving the housing in the direction of the arrow 280 shown until the outer surface of surgical tool 240, in which one or more tool disks (e.g., tool disk 244-i) are located, contacts the outer surface of tool actuator 230, in which one or more drive disks (e.g., drive disk 234-j) are located. In the example shown, tool actuator 230 is a segment of surgical robotic arm 220 at the distal end of surgical robotic arm 220. The proximal end of arm 220 is attached to a surgical robotic platform, such as in Figure 2 Not shown in the above Figure 1 An example of an operating table can be seen in the image.

[0029] The controller 210 controls the movement of various motorized joints in the surgical robot arm 220 (including the drive disk 234), thereby enabling the operation of the end effector 246 (its position and orientation, and its surgical function), which simulates the operation of the user input device. This operation is achieved via the mechanical transmission 245 within the surgical tool 240 when the surgical tool 240 has been engaged to transmit force or torque from the tool driver 230. The controller 210 can be implemented as a programmable processor, for example as... Figure 1 Part of the control tower 3. Controller 210 can respond to one or more user commands received via local or remote user input (e.g., joystick, touch control, wearable device, or other user input device communicating via console computer system 16). Alternatively, controller 210 can respond to one or more autonomous commands or controls (e.g., received from a trained surgical machine learning model executed by controller 210 or console computer system 16) or a combination thereof. These commands instruct movement of robotic arm 220 and operation of its attached end effector 246.

[0030] The end effector 246 can be any surgical instrument, such as jaws, cutting tools, endoscopes, unfolders, implantation tools, sutures, etc. Different surgical instruments, each with a different end effector 246, can be selectively attached (one at a time) to the robotic arm 220 for use during surgical or other medical procedures. Figure 2 The end effector 246 depicted in the example is a jaw located at the distal end of the surgical tool 240.

[0031] The robotic arm 220 includes a tool actuator 230 containing one or more actuators, such as actuators 238-j. Each actuator 238 may be a linear or rotary actuator with one or more corresponding electric motors (e.g., brushless permanent magnet DC motors), whose drive shafts may be coupled to a corresponding drive disk 234-j via a transmission mechanism (e.g., a gear train 236 achieving a given gear reduction ratio). The tool actuator 230 includes one or more drive disks 234, which may be arranged on a planar or flat surface of the tool actuator 230, wherein the figure illustrates several such drive disks arranged on the same plane of a flat surface. Each drive disk (e.g., drive disk 234-j) is exposed on an outer surface of the tool actuator 230 and is designed to mechanically engage (e.g., securely hold via snap-fit, friction, or other mating features) a mating tool disk 244-j of the surgical tool 240 to achieve direct torque transmission between the two. This can occur, for example, when the planar or flat surface of the surgical tool 240 and the corresponding or mating planar or flat surface of the tool actuator 230 come into contact with each other.

[0032] Furthermore, a motor driver circuit (not shown, but which may be mounted, for example, in tool driver 230 or elsewhere in surgical robot arm 220) is electrically coupled to the input drive terminal of the motor comprising one or more actuators in actuator 238. The motor driver circuit manipulates the power drawn from the motor according to a motor driver circuit input, in order to adjust, for example, the speed, position, or torque of the motor, which may be set or controlled by controller 210.

[0033] When the drive disc 234-j is mechanically engaged with the corresponding tool disc 244-j, the powered rotation of the drive disc 234-j causes the tool disc 244-j to rotate. For example, the two discs can rotate as a single unit, thereby imparting motion to a residual transmission 245, such as that connected to the end effector 246. This residual transmission includes gears, cables, chains, and / or another linkage or transmission 245 within the surgical tool 240 for controlling the movement and operation of the end effector 246. The end effector 246 is mechanically coupled to the transmission 245, which is mechanically coupled to the actuator 238. Gears, cables, chains, rods, screw drives, racks and pinions, and / or other linkages that impart motion from the actuator 238 to the end effector 246 are transmissions 236, 245, or linkages. The surgical end effector 246 is connected via transmissions 236, 245, such that movement of the actuator 238 causes movement or operation of the end effector 246. The compliance and elasticity in the transmission devices 236 and 245 can lead to a less precise response of the end effector 246 to the movement of the actuator 238.

[0034] Different surgical instruments 240 may have different numbers of tool discs, based on the type of movement and the number of degrees of freedom of movement performed by their end effectors, such as rotation, articulation, opening, closing, extension, retraction, pressure, etc. Furthermore, within the surgical instrument 240, more than one tool disc 244 can facilitate the individual movement of the end effector 246 to achieve a target, such as by sharing the load of two or more motors that respectively drive the mating drive disc 234, and / or by applying static preload to reduce compliance and / or recoil in the transmissions 236, 245 or the mechanical linkage from the actuator 238 to the end effector 246. The transmissions 236, 245 mechanically connect the end effector 246 to multiple actuators 238. Two actuators 238 operate to control the end effector 246 via corresponding transmissions. For example, within the surgical instrument 240, a transmission 245 converts torque from two drive discs 234 (via corresponding tool discs 244) to perform complementary actions with the same degree of freedom. For instance, the first drive disc 234-i rotates a roller within the housing of the surgical instrument 230 to receive one end of a cable, and the second drive disc 234-j rotates another roller within the housing of the surgical instrument 230 to receive the other end of the cable. Alternatively, two tool discs 234-i, 234-j can be used to extend and retract the end effector along a single axis, one disc for extension and the other for retraction (e.g., via different cables). This contrasts with actuators that also move with one degree of freedom (e.g., extending and retracting longitudinally along a single axis of movement) but require only a single tool disc to control their entire range of motion. Furthermore, in the case where the end effector 246 is a jaw, two or more tool discs 244 can collaboratively control the movement of the jaw for load sharing.

[0035] In some implementations, when the surgical tool 240 is first attached to or mounted on the tool driver 230, such that the tool disk and the corresponding drive disk are substantially coplanar and coaxially aligned (although the tool disk and drive disk may not yet be successfully engaged), the controller 210 initially detects the type of the surgical tool 240. After the surgical tool 240 is attached to the tool driver 230 such that the tool disk is brought to be aligned with and superimposed on the corresponding drive disk (although not necessarily mechanically engaged), and after obtaining tool disk information, for example, read by the controller 210, the controller 210 performs an engagement process to detect when all tool disks 244 expected to be attached to the corresponding drive disk 234 are mechanically engaged with their respective drive disks 234 (e.g., their mechanical engagement has been achieved, or the tool driver 230 is now considered to be engaged with the tool 240). That is, attaching the surgical tool 240 to the tool driver 230 does not necessarily ensure the correct fit required for the mechanical engagement of the tool disks 244 with the corresponding drive disks 234 (e.g., due to misalignment of the fitting features). The engagement process may include activating one or more motors driving the actuator (e.g., actuator 238-j) of the corresponding drive disk 234-j. Then, based on one or more monitored motor operating parameters of actuator 238-j, mechanical engagement between tool disk 244-i and drive disk 234-j can be detected while the actuator is driving drive disk 234-j. This process can be repeated for each drive disk 234 (in the tool driver 230) of the corresponding tool disk 244 expected to be currently attached (e.g., determined as based on tool disk information obtained based on the specific surgical tool 240 currently attached).

[0036] When a particular type of surgical tool 240 is detected to be attached to the tool driver 230, the controller 210 activates one or more actuators (e.g., motors) of the tool driver 230 that were previously associated with that type of surgical tool 240. In some embodiments, each actuator 238 associated with the corresponding drive disk 234 of the surgical tool 240 may be activated simultaneously, sequentially, or in a combination of simultaneous and sequential activation. Figure 3An example of a surgical tool 240 is shown, which utilizes four tool discs, such as tool disc 244-i, arranged coplanarly on mating surfaces of its housing. Two of the tool discs 244 facilitate movement and / or activation of at least a portion of an end effector 246. Once engaged, a drive disc 234 is concentrically aligned with tool disc 244. Their respective disc surfaces contact each other and engage coupling features (e.g., protrusions and pawls) (depicted as solid circles) on their disc surfaces. In this particular example, the dimensions of each coupling feature (e.g., protrusion) are set such that it engages within any one of the features (e.g., pawls or recesses) once two complementary features are aligned for mechanical engagement. Engagement is provided, for example, when each pin-cavity pair interlocks.

[0037] Figure 3 This is a block diagram illustrating an example of a surgical tool 240, a tool actuator 230, and a controller 210. The controller 210 includes its programming processor 312, which can be integrated into the surgical robot system 1. Figure 1 In, for example, as a shared microprocessor and program memory within control tower 3. Alternatively, it can be in a remote computer (such as...) Figure 1 The controller 210 is implemented in a room different from the operating room or in a building different from the surgical site, as shown. Furthermore, the controller 210 may also include (though not shown) user interface hardware (e.g., keyboard, touchscreen, microphone, speaker) that enables manual control of the robotic arm and its attached tools 240, power supply (e.g., battery), and other components typically associated with electronics for controlling the surgical robotic system.

[0038] Memory 314 is coupled to one or more processors (generally referred to herein as "processors") in processor 312 to store instructions for execution by processor 312. In some embodiments, the memory is non-transitory and may store one or more program modules (e.g., algorithms or instructions), including tool control 320 and engagement control 316, whose instructions configure processor 312 to perform the engagement and control processes described herein. In other words, processor 312 may operate under the control of the execution of programs, routines, or instructions stored in memory 314 as part of tool control 320 and engagement control 316 to perform methods or processes according to the aspects and features described herein.

[0039] In response to the detection of attachment of surgical tool 240 to tool driver 230, engagement control 316 performs (or more precisely, configures processor 312 to perform) a process for detecting mechanical engagement of tool disk 244 with corresponding drive disk 234 (which is driven by an actuator), such as engagement of tool disk 344-i with corresponding drive disk 334-i. Engagement control 316 generates a notification to the operator of the surgical robot system based on whether engagement of tool disk 244 and drive disk 234 has been detected, or based on a countdown timer expiring if engagement has not been detected. This notification may indicate that engagement has occurred, making surgical tool 240 ready for use, or that engagement has not occurred and therefore surgical tool 240 should be reattached.

[0040] After engagement, controller 210 is configured to return actuator 238 to its established position. A zero or initial position is established for actuator 238 to place end effector 246 in an established or initial state (e.g., jaws open or stitcher not stitching). The position of actuator 238 initially engaged can be designated as the established state. Alternatively, actuator 238 is operated to detect that end effector 246 has transitioned to the established state, such as by providing a sensing current to actuator 238. This return can be performed as part of engagement control 316, tool control 320, or a separate control.

[0041] The controller 210 is configured to control the actuator 238 to apply static pretension. Taking into account the compliance and / or elasticity in the transmissions 236, 245, the static pretension fixes or sets the recoil of the transmissions 236, 245. Any slack in the transmissions 236, 245 from the different actuators 238 to the end effector 246 is removed or reduced, thereby fixing the amount of recoil caused by the compliance in the transmissions 236, 245. In the case where multiple actuators 238 are connected to the end effector 246, the static pretension allows simultaneous control of the end effector 246, even when the transmissions 236, 245 have high compliance.

[0042] Static pretension is initially applied after engagement and before control to operate the end effector 246 on the patient's tissue. This application of static pretension occurs as part of homing or as a separate control, and can therefore be part of engagement control 316, tool control 320, or another control process.

[0043] To generate static pretension, the different actuators 238 operate in opposite directions. When two actuators 238 are connected to the end effector 246 via transmissions 236, 245, one actuator 238 operates in opposite directions to the other. For example, two or more actuators 238 rotating in the same direction (their corresponding drive discs 234 rotating in the same direction) are driving the same output shaft inside the surgical instrument 240 (due to the transmissions 236, 245 connected to the corresponding tool discs in the surgical instrument 240). Now, if two actuators 238 are signaled to move in opposite directions, the compliance in the transmissions 236, 245 is removed or reduced. When the drive disc 234 engages the corresponding tool disc 244, the opposing movements pretension the transmissions 236, 245. In other embodiments, actuators 238 operate in opposite directions to each other by attempting to move end effectors 246 by different amounts, such as both rotating to move in the same direction, but one actuator 238 rotating by a larger amount (e.g., the other actuator 238 not rotating or rotating less).

[0044] One or both of the actuator's motor operating parameters can be monitored to detect pretension to the desired level. The control used to apply the pretension is in torque control mode. The current drawn by one or both motors is monitored until a threshold level of tension is generated in the transmissions 236, 245. Once the threshold torque is applied to the transmissions 236, 245, a static level of pretension is applied. This provides the desired static pretension. In alternative embodiments, other control modes may be used.

[0045] Figures 4 to 6 A simplified lumped model is shown to illustrate the generation of static pretension. To precisely control the motion (e.g., one-dimensional motion) of the end effector 246, two actuators 238 are coupled to the end effector 246 via transmissions 236, 245. In this lumped model, the actuators 238 are located within the block representing the end effector 246. The model includes a recoil gap between the inner contact surfaces of the actuators 238 and the block representing the end effector 246. The actuators 238 are connected by a spring constant k. e The flexible surface contacts the inner surface of the block, and the spring constant typically represents the transmission slack. Two resistances are modeled to act on actuator 238: i) friction, ii) a force with a spring constant k. 弹簧 The pre-existing spring force. Precise control of the end effector block is performed using only sensing information from the actuator (control input) (e.g., position, current, torque, etc.). The actual position of the end effector block is not directly measured, but precisely estimated and controlled.

[0046] exist Figure 4In this design, the compliance and / or elasticity of the existing recoil and drive mechanisms are problematic because the actual position of the end effector block can be anywhere within the recoil + compliance region (i.e., the cavity in which the end effector block can be positioned). Furthermore, external forces that resist or facilitate the movement of the end effector 246 cause positional changes in the block within the recoil and compliance regions, and actuator sensor measurements will not capture these positional changes.

[0047] There are two actuator mapping settings to control the movement of the block while resisting external forces from different directions. Figure 5 and Figure 6 These two control schemes are shown. Figure 5 It is shown that the actuators 238 have been moved away from each other in opposite directions (i.e., moved to move the end effector 246 in opposite directions). Figure 6 It is shown that actuators 238 have moved relative to each other (i.e., moved to move end effector 246 in relative directions). For Figure 5 or Figure 6 Any external force setting in any arrangement of actuators 238 resists free movement of the end effector block. Figure 5 and Figure 6 This indicates the application of static pretension to the actuator 238 of the end effector 246.

[0048] In the presence of small institutional flexibility, large k e In certain situations, a master-slave control strategy can be used to implement actuator mapping. One actuator 238 will guide the movement, and the other actuator 238 will resist it, thus ensuring that the recoil is closed and that there is always a contact surface between the actuator 238 and the inner surface of the block. In this control strategy, the key is that the resistance applied by the slave actuator 238 passes through the master actuator 238, so that the internal recoil of the mechanism is completely consumed. When there is relatively large compliance and elasticity in the transmissions 236 and 245, the master-slave actuator mapping scheme may also not work. Due to the greater compliance, when the width of the recoil region changes (i.e., becomes larger), the recoil region may not be completely eliminated. The actuators 238 have only a limited rated torque output capability, and using a stronger actuator 238 may cause plastic deformation of the transmissions 236 and 245, leading to mechanical failure.

[0049] Instead of a master-slave arrangement, static pretension is applied. Static pretension is applied during the homing routine or after engagement and before surgical manipulation of the end effector 246. Static tension is applied based on a threshold, such as a predetermined calibrated torque applied in opposite directions from each actuator 238 to the inner surface of the block, as... Figure 5 and Figure 6 As shown.

[0050] During surgical procedures, controller 210 is configured to control actuator 238 to move surgical actuator 246. For example, actuator 238 is moved or repositioned for suturing. After applying static pretension, the operator can command movement of one or more joints of the surgical robotic arm 220, including commanding movement or manipulation of the end effector 246. As described above, commands are received from or derived from one or more UIDs 14 as spatial state signals converted into corresponding control signals, which controller 210 provides (e.g., desired motor speed or current and direction of rotation) to energize one or more actuators 238 of the tool driver 230, which is part of tool control 320. When the end effector 246 is under or subjected to any external load, such as from patient tissue, the end effector 246 is moved, such as manipulated.

[0051] Actuators 238 are operated to move in cooperation with each other rather than in opposition to each other. In cases where two or more actuators 238 cooperate in controlling the movement of end effector 246, such as when two or more tool disks 244 impart the same degree of freedom to end effector 246, controller 210 further performs cooperative control techniques to ensure that the actuators operate in a complementary manner when moving end effector 246. For example, when two or more actuators are used to control the opening, closing, sewing, or application of clamping force of the jaws of end effector 246, controller 210 utilizes multi-actuator operation control techniques to send position commands to move end effector 246 to the commanded position or operation (e.g., sewing). For example, the same position command is sent to both actuators 238 (e.g., the same polarity (direction of rotation of their motors) and the same motor current value are supplied to each of the actuators 238). However, in some implementations, there may be some compensation for the motion of the actuators that are complementary to each other, such as reversing the polarity when the rotation direction of actuator 238 is different, adjusting the gain (e.g., the gain of the commanded motor current) when the properties of the motor are different, etc.

[0052] Actuator 238 changes position while maintaining static pretension. Backlash and / or compliance compensation is provided even during surgical procedures in the control of end effector 246. Backlash clearance is maintained during control. Both actuators 238 are operated to move the end effector 246 in the same direction along the one-dimensional operating space of the end effector 246. Because the initial relative positions of the actuators 238 used for this operation have static pretension applied to the transmissions 236, 245, this coordinated or identical movement results in maintaining static pretension while displacing the end effector 246. For example, actuators 238 positioned with pretension to reduce or eliminate compliance and / or elasticity (see...). Figure 5 and Figure 6Both move by the same amount in the same direction. As a result, the tension applied to the transmission devices 236 and 245 by the actuator 238 is maintained, while the actuator 238 and the end effector block 246 are moved in the same direction and by the same amount in the lumped model.

[0053] Once pretension is established using torque control mode, controller 210 switches to position control mode for tool control 320. When the desired pretension torque is reached, control switches to position control mode for the two actuators 238. Position control is used to maintain the corresponding or relative position of actuators 238 relative to each other. At this point, the pretension torque is established. Figure 5 or Figure 6 One mapping scheme is shown. The actuator position is marked as zero (e.g., homed), and position control is used for each actuator relative to the marked zero actuator position. Position commands that move actuator 238 by the same amount are sent to actuator 238. These position commands (e.g., the same position commands for both actuators 238) ensure that the relative distance (and therefore recoil) between actuators 238 remains constant throughout operation. The drive shaft of the motor of actuator 238, scaled for the differences in transmissions 236, 245, is rotated to change the position for the same amount and direction of movement of end effector 246.

[0054] The effects of variable backlash are eliminated or reduced due to the mechanism's compliance by fixing the backlash width with static pretension (e.g., fixing it in the return routine). During surgical procedures, the actuators 236 and 245 resist any external force interference while precisely following motion commands due to the pretension. Position tracking errors caused by external forces may arise solely from the elastic deformation of the mechanism.

[0055] Figure 7 An embodiment of a method for controlling surgical tools or instruments in a surgical robotic system is shown. The method utilizes the reduction of recoil caused by the compliance and / or elasticity of the tool during control of tool operation.

[0056] This method is by Figure 1 , Figure 2 and / or Figure 3 The method is performed using a surgical robotic system or another surgical robotic system. It is performed with two or more motors driving the same motion of the surgical instrument, such as suturing tissue with a surgical stapler. The processor of a controller or other controller uses actuator 238, end effector 246, and linkages (e.g., transmissions 236, 245) between actuator 238 and end effector 246 to perform the method. In addition to end effector 246, the method can also be performed on other joints or movable parts of the surgical instrument.

[0057] The actions may be performed in the order shown or a different order. For example, actions 700 and 702 may be performed simultaneously or as part of a single action. Similarly, actions 708 and 710 may be performed simultaneously or as part of a single action.

[0058] Additional, different, or fewer actions may be provided. For example, when switching between other control modes or when the same control mode is used for both pre-tensioning and tool operation (e.g., using calibrated positioning in a position mode for applying tension instead of a torque control mode), action 706 is not performed. Actions for engagement, repositioning, user input, display, and / or surgical procedures may be included.

[0059] In action 700, the controller overcomes variable recoil caused by the compliance and / or elasticity of the connection from the actuator to the surgical tool 240 (such as the end effector 246 of the surgical tool 240). In action 700, any given force in the linkage is exhausted or reduced. By applying tension or torque, the recoil width is reduced or eliminated.

[0060] In action 702, reduction is provided by operation or actuation of a motor or actuator. In other embodiments, reduction is performed in other ways.

[0061] Motors are actuated or operated to reduce recoil. Motors operate in opposite directions to each other. For example, one motor is moved to stitch or operate end actuator 246, and another motor moves in a different direction (i.e., does not stitch or operate), remains in place, or moves less, to the opposite degree of movement by one motor. To cooperate, both motors move to the same degree. To oppose, the two motors move to different degrees. The result of the opposing movements is to tighten or remove some of the given forces in the link. The unequal forces applied along the link through the end actuator result in a reduced recoil width. Tension is applied through the link. Tension is generated by the opposing actuation of the link of the end actuator 246, which engages with the motor of actuator 238.

[0062] In one implementation, actuation occurs under torque control. The torque applied by the motors is monitored. The motors are controlled to apply a given torque. When one or both motors reach a threshold torque, a threshold amount of tension is applied via the linkage and end effector 246. Once the tension is reached, the motors do not apply additional torque relative to each other, thus providing static preload to dissipate recoil.

[0063] The actuation in action 702, used to reduce the position in action 700, is performed as part of homing. Prior to action 700, the surgical tool 240 engages with the tool driver 230. Two or more actuators 238 are engaged to control a given one-dimensional operation of a connector or end effector. Once engaged, homing is performed. Once engagement is detected, homing can assign the actuator position (i.e., axis rotation angle) to a zero position. Alternatively, other homing methods are used. Tension in action 700 is applied after homing or before a surgical procedure using a controlled connector (e.g., end effector 246). Alternatively, tension in action 700 is applied, and then homing is performed (e.g., assigning a zero or initial position to an axis rotation angle, where a threshold amount of tension or torque is provided by the actuator). In either case, the reduction in action 700 is performed as part of the homing process. Static pretension is established as part of engagement, and homing is applied as part of a process to prepare the surgical tool 240 for use with the patient.

[0064] In action 706, when the threshold torque is reached due to the actuation of action 702 or the reduction of action 700, the controller switches from torque control to position control. To apply tension to reduce recoil width, the motor operates under torque control. The motor is operated to provide a given amount of torque corresponding to the desired static tension in the linkage. The motor's current draw or other operating characteristics can be monitored to measure the torque or force applied from one motor to another via the linkage and end effector 246. Current draw is related to torque. The threshold torque can vary for different surgical tools 240 and / or applications. This threshold is determined experimentally or based on simulations using the design of the motor and linkage.

[0065] Once torque is reached, the motor exhibits a relative angular rotation that provides tension. These relative angular rotations are maintained, thus switching control to position control mode. In cases where gear transmission results in rotations of varying proportions of movement or force, the relative angular rotation can be shifted while providing the same preload during operation. The position of the drive shaft (i.e., angular rotation or orientation) is marked as the original position and / or otherwise stored, such that the amount of rotation in position control mode maintains the preload at or within the tolerance of the threshold torque through position changes.

[0066] In action 708, the controller drives the surgical tool 240. The drive is controlled in position control mode. The angular rotation or orientation of the motor's drive shaft is controlled to drive the end effector 246 or other parts of the surgical tool 240, thereby operating the end effector 246 or other parts of the surgical tool 240. A deviation from the marked position, such as a commanded rotation amount, is used.

[0067] Action 710 illustrates one embodiment of driving tool 240. Other methods may be used to operate tool 240 with engagement motor.

[0068] In action 710, the controller actuates the motor. The engaging connection between the motor and the end effector 246 transmits force from the actuated motor to the end effector 246. The motor is operated to change position, such as rotating a given amount in position control mode.

[0069] The motors cooperate to operate the actuators. The motors rotate in a direction to cause the same movement of the end effector based on the linkage. The amount of movement is provided by both motors. For example, the two motors move by equal amounts in the same direction. The same command can be given to each motor. In the presence of scaling contributions, one motor may move more or less than the other. Where the linkage provides a reverse connection to end effector 246, the cooperating motors may move in opposite directions (not relative to each other).

[0070] In action 708, the surgical tool 240 operates under an external load. Forces from the tissue acting on the end effector are overcome. Position control provides operation of the tool regardless of the direction and / or amount of the external load due to static pretension. After repositioning, the surgical tool 240 (such as the end effector 246) is operated for surgical purposes (e.g., tissue suturing). During telescopic manipulation, to rotate, manipulate, or translate the surgical tool in one direction, two motors rotate in a specific direction (e.g., both motors rotate in the same direction, or one motor rotates in one direction while the other rotates in a different direction), relying on transmissions 236, 245, or other linkages from actuator 238 to the end effector 246 of the surgical tool 240. The position of the drive shaft is controlled to move from a current position (e.g., a marked position or a starting position) to another position.

[0071] The operation of action 708 is performed while maintaining static pretension. The motor is actuated in action 710 to move cooperatively. Since the motor begins at a position where the desired tension or torque is applied via the linkage, cooperative actuation causes operation of the end effectors while maintaining tension or relative torque between the motors. In position mode, the motors are moved to cause the same movement of the end effectors 246, thus causing the motors to move together without changing the backlash width. This occurs even when the external load is variable.

[0072] The foregoing description of exemplary embodiments of the invention, including those described below in the abstract, is not intended to be exhaustive or to limit the invention to the specific forms disclosed. While specific embodiments and examples of the invention have been described herein for illustrative purposes, various modifications are possible within the scope of the invention, as will be recognized by those skilled in the art. These modifications can be made to the invention based on the detailed description above. The terminology used in the following claims should not be construed as limiting the invention to the specific embodiments disclosed in the specification. Rather, the scope of the invention is fully defined by the following claims, which will be interpreted according to the claims.

Claims

1. A computer program product comprising instructions that cause a surgical robotic system including a controller and surgical instruments to perform the following steps: Actuates a first link engaged with a first motor and a second link engaged with a second motor, the first link and the second link being mechanically coupled to the end effector of the surgical instrument, the first motor and the second motor operating in opposite directions under torque control using a control input for the torque of the input drive ends of the first motor and the second motor; When the threshold torque is reached, the torque control of the first motor and the second motor is switched to position control; as well as The end effector is driven under the position control of the first motor and the second motor, and the first motor and the second motor operate in coordination with each other.

2. The computer program product according to claim 1, wherein, Actuation includes absorbing the recoil from the first motor and the second motor through the first link and the second link to the end effector.

3. The computer program product according to claim 1, wherein, The surgical instrument has one-dimensional motion of the end effector controlled by the first motor and the second motor, and wherein actuation includes actuating the first motor to drive the end effector in a first direction using the first link and actuating the second motor to drive the end effector in a second direction opposite to the first direction using the second link.

4. The computer program product according to claim 1, wherein, Actuation includes repositioning the first motor and the second motor to the end effector, and driving includes driving the end effector during surgery after repositioning.

5. The computer program product according to claim 4, wherein, Actuation includes applying a static pretension during the homing period, the static pretension corresponding to the threshold torque, and wherein actuation includes actuation while maintaining the static pretension.

6. The computer program product according to claim 1, wherein, The conversion includes changing the control mode from torque control to position control.

7. The computer program product according to claim 1, wherein, The conversion includes sensing the current drawn by the first motor and / or the second motor for the torque control and associating the current draw with the torque.

8. The computer program product according to claim 1, wherein, The drive includes moving the first link and the second link via the first motor and the second motor, wherein the relative position of the drive shafts of the first motor and the second motor is maintained under an external load on the end effector.

9. The computer program product according to claim 1, wherein, The conversion includes marking the positions of the drive shafts of the first motor and the second motor, and wherein the driving in the position control includes controlling the position of the drive shafts from the marked positions.

10. The computer program product according to claim 1, wherein, The drive includes controlling the first motor and the second motor with the same position command, such that when the end effector moves under the control of the first motor and the second motor, the drive shafts of the first motor and the second motor maintain the same relative position.

11. A surgical robot system for controlling surgical instruments, the surgical robot system comprising: A surgical end effector, which is actuated by a first actuator and a second actuator via a transmission device; and A controller configured to drive the first and second actuators in opposite directions to generate static pretension as part of the homing of the first and second actuators, and to drive the first and second actuators in a coordinated manner to move the surgical end effector while maintaining the static pretension.

12. The surgical robot system of claim 11, wherein, The surgical end effector includes a suture device connected to a robotic arm, wherein the static pretension stabilizes the recoil of the drive, and wherein the controller is configured to drive the first actuator and the second actuator to perform suturing while maintaining the recoil.

13. The surgical robot system of claim 11, wherein, The controller is configured to be driven in torque control mode to apply the static pretension, and is configured to be driven in position control mode to move the surgical end effector.

14. The surgical robot system of claim 11, wherein, The controller is configured to drive the first actuator to apply the static pretension by operating the first actuator in opposition to the second actuator, and to drive the surgical end effector to move by cooperating the first and second actuators with each other.

15. The surgical robot system of claim 11, wherein, The controller is configured to move the surgical end effector under an external load, the surgical end effector being moved by a command sent to the same position for both the first and second actuators.

16. A computer program product comprising instructions that cause a surgical robotic system including a controller and surgical tools to perform the following steps: Overcoming variable recoil caused by the compliance of the engagement coupling between the actuator and the surgical instrument, wherein the actuation of the actuator relative to the surgical instrument is driven in opposite directions; and The surgical tool is actuated by driving the actuator through the engagement coupling, wherein... The actuation includes controlling the actuator with the same position command, such that when the surgical tool moves under the control of the actuator, the same relative position of the actuator's drive shaft is maintained.

17. The computer program product according to claim 16, wherein, Overcoming this includes control in torque control mode, and actuation includes control in position control mode.

18. The computer program product according to claim 16, wherein, Actuation includes driving the actuators in a cooperative manner.

19. The computer program product according to claim 16, wherein, Actuation includes driving under an external load on the surgical instrument.

20. The computer program product according to claim 16, wherein, Overcoming includes overcoming as part of the repositioning of the actuator relative to the surgical instrument.

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