Patent Application
20210113287
This application claims the benefit under 35 U.S.C. § 119 of United Kingdom Patent Application No. 1915270.1 filed on Oct. 22, 2019 which is hereby incorporated herein by reference in its entirety for all purposes.
It is known to use robots for assisting and performing surgery.
A control system 118 connects the surgeon console 112 to the surgical robot 100. The control system receives inputs from the surgeon input device(s) and converts these to control signals to move the joints of the robot arm 104 and end effector 110. The control system sends these control signals to the robot, where the corresponding joints are driven accordingly.
It is known for the jaws of an end effector to be individually driven by cables. These cables may be utilised to drive opening and closing of the jaws so as to grip and release an object between them. The same cables may also be used to drive a yawing motion of the jaws so as to cause the jaws to rotate in the same direction with the opening angle of the jaws remaining constant. Since the same cables are used to drive both the opening/closing and yawing motion of the jaws, these operations are not independent. As a result of this, the whole range of opening/closing motion cannot be accessed over the whole range of yawing motion, and vice versa.
Thus, there is a need for a control system which better mediates the interdependence of the opening/closing and yawing motion of an end effector.
According to an aspect of the invention, there is provided a control system for controlling manipulation of a surgical instrument in response to manipulation of a remote surgeon input device, the surgical instrument comprising an end effector having opposable first and second end effector elements connected to a shaft by an articulated coupling, the control system configured to: receive a command from the surgeon input device to both (i) change the orientation of the end effector, and (ii) open the first and second end effector elements relative to each other; in response to the command to change the orientation of the end effector, determine an angle θ between the longitudinal axis of the articulated coupling and the end effector; in response to the command to open the first and second end effector elements, determine an opening angle ϕ between the first and second end effector elements; compare θ to a maximum angle θmax between the longitudinal axis of the articulated coupling and the end effector; and if θ>θmax, drive the first and second end effector elements to rotate such that (i) the angle between the longitudinal axis of the articulated coupling and the end effector is θmax, and (ii) the opening angle between the first and second end effector elements is ϕ.
The control system may be configured to, if θ≤θmax, drive the first and second end effector elements to rotate such that (i) the angle between the longitudinal axis of the articulated coupling and the end effector is θ, and (ii) the opening angle between the first and second end effector elements is ϕ.
The angle θ may be between the longitudinal axis of the articulated coupling and an axis which bisects the end effector elements. θmax may be a function of ϕ and αmax, where αmax is the maximum rotation from the longitudinal axis of the articulated coupling of the end effector element in the commanded direction of rotation.
Optionally, θmax=αmax−ϕ/2.
The control system may be configured to determine the opening angle ϕ between the first and second end effector elements by: in response to the command to open the first and second end effector elements, determine an opening angle ψ; compare ψ to a maximum angle ϕmax between the first and second end effector elements; and if ψ>ϕmax, drive the first and second end effector elements to rotate such that the opening angle between the first and second end effector elements ϕ=ϕmax.
The control system may be configured to, if ψ≤ϕmax, drive the first and second end effector elements to rotate such that the opening angle between the first and second end effector elements ϕ=ψ.
The command from the surgeon input device to change the orientation of the end effector may comprise a rotation of at least a portion of the surgeon input device in its workspace.
The surgeon input device may comprise a body and a trigger, and the command from the surgeon input device to open the first and second end effector elements relative to each other may comprise a movement of the trigger relative to the body.
The command from the surgeon input device to open the first and second end effector elements relative to each other may comprise a rotation of the trigger away from the body.
The angle between the trigger and the body at the end of the rotation may be proportional to ϕ.
The command from the surgeon input device to open the first and second end effector elements relative to each other may comprise a linear translation of the trigger relative to the body.
The articulated coupling may comprise a first joint driveable by a first pair of driving elements, and a second joint driveable by a second pair of driving elements. The control system may be configured to drive the first and second end effector elements to rotate by: commanding a first force to be applied to the first pair of driving elements so as to cause the first end effector element to rotate about the first joint; and commanding a second force to be applied to the second pair of driving elements so as to cause the second end effector element to rotate about the second joint.
The articulated coupling may further comprise a third joint driveable by a third pair of driving elements. The control system may be configured to: in response to the command to change the orientation of the end effector, determine an angle Ω between the longitudinal axis of the shaft and the articulated coupling; and drive the end effector to rotate about the third joint by Ω.
The control system may be configured to drive the end effector to rotate about the third joint by commanding a third force to be applied to the third pair of driving elements so as to cause the end effector to rotate about the third joint.
The control system may be configured to: following driving the first and second end effector elements to rotate such that the angle between the longitudinal axis of the articulated coupling and the end effector is θmax, receive a further command from the surgeon input device to increase the opening angle between the first and second end effector elements relative to each other; in response to the further command: determine an opening angle ϕ′ between the first and second end effector elements; determine an angle θmax′ between the longitudinal axis of the articulated coupling and the end effector, where θmax′ is a function of ϕ′; and drive the first and second end effector elements to rotate such that (i) the angle between the longitudinal axis of the articulated coupling and the end effector is θmax′, and (ii) the opening angle between the first and second end effector elements is ϕ′.
Optionally, θmax′=αmax−ϕ′/2, where αmax is the maximum rotation from the longitudinal axis of the articulated coupling of the end effector element in the commanded direction of rotation.
Each of the first and second pairs of driving elements may comprise cables.
The first force, second force and/or third force may be tension forces.
The opposable first and second end effector elements may be one of: a pair of jaws, a pair of scissors, and a needle driver.
The present invention will now be described by way of example with reference to the accompanying drawings. In the drawings:
The following describes controlling a surgical robotic instrument from a remote surgeon console. The instrument and console form part of a surgical robotic system of the type illustrated in
The surgical instrument is supported by a robot arm. The robot arm is itself supported by a base. During surgery, the base is secured to part of the operating theatre, for example the floor, ceiling, cart or patient bed. The robot arm remains at all times external to the patient. The robot arm comprises a series of arm links interspersed with joints. These joints may be revolute joints. The end of the robot arm distal to the base can be articulated relative to the base by movement of one or more of the joints. The surgical instrument attaches to a drive assembly at the distal end of the robot arm. This attachment point is external to the patient.
The surgical instrument has an elongate profile, with a shaft spanning between its proximal end which attaches to the robot arm and its distal end which accesses the surgical site within the patient body. The proximal end of the surgical instrument and the instrument shaft may be rigid with respect to each other and rigid with respect to the distal end of the robot arm when attached to it. An incision is made into the patient body, through which a port is inserted. The surgical instrument may penetrate the patient body through the port to access the surgical site. Alternatively, the surgical instrument may penetrate the body through a natural orifice of the body to access the surgical site. At the proximal end of the instrument, the shaft is connected to an instrument interface. The instrument interface engages with the drive assembly at the distal end of the robot arm. Specifically, individual instrument interface elements of the instrument interface engage individual drive assembly interface elements of the drive assembly. The instrument interface is releasably engageable with the drive assembly. The instrument can be detached from the robot arm manually without requiring any tools. This enables the instrument to be detached from the drive assembly quickly and another instrument attached during an operation.
At the distal end of the surgical instrument, the shaft is connected to an end effector by an articulated coupling. The end effector engages in a surgical procedure at the surgical site.
The joints illustrated in
The end effector elements 209 and 210 are independently rotatable. The end effector elements can be rotated in opposing rotational directions. For example, the end effector elements can be rotated in opposing rotational directions towards each other by applying tension to driving elements A2 and B1. This closes the end effector elements together, which is useful for (i) gripping an object between the end effector elements, such as tissue or a needle or thread, and/or (ii) cutting an object between the end effector elements, such as tissue or thread. The end effector elements can be rotated in opposing rotational directions away from each other by applying tension to driving elements A1 and B2. This opens the end effector elements, which is useful for (i) releasing an object which has been grasped between the end effector elements, and/or (ii) reopening a pair of scissor end effector elements ready for another cutting action. Both end effector elements can be rotated in the same rotational direction, by applying tension to driving elements A1 and B1 or alternatively A2 and B2. This causes the end effector elements to yaw about the pivot axes 208 and 212. This is useful for enabling the end effector to access a different part of the surgical site. Alternatively, one end effector element can be rotated (in either rotational direction) whilst the other end effector element is maintained in position, by applying tension to only one of driving elements A1, A2, B1, B2. Thus, both a gripping motion and a yawing motion of the end effector are enabled by manipulating the same pairs of driving elements: A1, A2 for the first end effector element 209, and B1, B2 for the second end effector element 210.
Any type of instrument having opposable end effector elements is relevant to the following description. A first exemplary type is cutting instruments, for which the end effector elements engage so as to cut tissue or another object between the end effector elements. A second exemplary type is gripping instruments, for which the end effector elements engage so as to grasp tissue or another object between the end effector elements.
The surgeon console comprises one or more surgeon input devices. Each surgeon input device enables the surgeon to provide a control input to the control system. A surgeon input device may, for example, be a hand controller, a foot controller such as a pedal, a touch sensitive input to be controlled by a finger or another part of the body, a voice control input device, an eye control input device or a gesture control input device. The surgeon input device may provide several inputs which the surgeon can individually operate.
The surgeon may rotate the trigger 302 relative to the body 301 of the hand controller in order to command the end effector elements 209, 210 of the instrument to close in a gripping/closing motion or to open in a releasing/opening motion. For example, the surgeon may rotate the trigger 302 towards the body 301 of the hand controller to command a gripping/closing motion. The surgeon may rotate the trigger 302 away from the body 301 of the hand controller to command a releasing/opening motion. The surgeon may rotate the body of the hand controller in the hand controller workspace to command a change in orientation of the end effector elements.
A control system connects the surgeon console to the surgical robot. The control system comprises a processor and a memory. The memory stores, in a non-transient way, software code that can be executed by the processor to cause the processor to control the surgeon console and robot arm and instrument in the manner described herein. The control system receives the inputs from the surgeon input device(s) and converts these to control signals to move the joints of the robot arm and/or the joint(s) of the articulated coupling and/or the joint(s) of the end effector. The control system sends these control signals to the robot arm, where the corresponding joints are driven accordingly. Manipulation of the surgical instrument is thereby controlled by the control system in response to manipulation of the surgeon input device.
When the control system is controlling an instrument having opposable end effector elements, on detecting an opening motion of the hand controller, the control system responds by commanding a force to be applied to the driving elements of the end effector elements to cause the end effector elements to rotate in opposing rotational directions away from each other. Referring to
On detection of a second motion of the hand controller in the hand controller workspace, the control system may respond by commanding articulation of any one or combination of: (i) the joints of the surgical robot arm, (ii) the joints of the articulated coupling 203 of the surgical instrument, and (iii) the joints of the end effector. This commanded articulation causes the pose of the end effector to change as directed by the second motion. For example, the second motion may be a rotation of the body 301 of the hand controller. As another example, the second motion may be manipulation of a further input on the hand controller, for example movement of a further trigger. That movement may be a rotation of the further trigger relative to the body of the hand controller. Alternatively, or in addition, the further trigger could translate linearly relative to the body 301.
Thus, the control system may respond to detection of the second motion (such as rotation) of the body of the hand controller by, at least in part, commanding forces to be applied to the driving elements of the end effector elements to cause the end effector elements to rotate. For example, referring to
The same driving elements A1, A2 and B1, B2 are utilised to drive rotation of the end effector elements for both opening and closing the end effector elements relative to each other and yawing the end effector. Thus, the opening/closing and yawing operations are not independently driven.
Referring to
Each end effector element is limited in how far it can rotate about the axis of its connected joint. The maximum rotational angle between the longitudinal axis 402 of the furthest end effector and the longitudinal axis 401 of the articulated coupling 203 is αmax. For example, αmax may be in the range 60° to 90°. αmax may be in the range 65° to 80°. αmax may be 70°. αmax may be instrument dependent. The end effector elements may be opened to a spread angle ϕ, and then yawed clockwise as shown in
In
The end effector elements may also be limited in how far they can rotate away from each other. For example, the opening angle may be limited to ϕmax. ϕmax may be instrument dependent. For example, ϕmax may be in the range 40° to 90°. ϕmax may be in the range 45° to 75°.
At step 501 of
As described above, the command from the surgeon input device to change the orientation of the end effector may be a rotation of the surgeon input device in its workspace. The surgeon input device may be connected to the surgeon console by an articulated linkage, optionally including a gimbal assembly. A position sensor may be included on each movable joint of the articulated linkage. The control system receives the sensed positions of each joint of the articulated linkage. From the known order, masses and lengths of the links and joints in the articulated linkage, and the received sensed positions, the control system determines the change of orientation of the surgeon input device. From the change of orientation of the surgeon input device, the control system determines the commanded change of orientation of the end effector.
The command from the surgeon input device to open the end effector elements relative to each other may be a rotation of the trigger away from the body of the surgeon input device. Alternatively, a command from the surgeon input device to open the end effector elements relative to each other may be a linear translation of the trigger relative to the body. For example, the hand controller 300 of
At step 502, in response to the command to change the orientation of the end effector, the control system determines an angle θ between the longitudinal axis of the articulated coupling and the end effector.
The angle θ is that determined to effect the change in orientation commanded by the surgeon input device. The angle θ may be proportional to the angle through which the surgeon input device has rotated in its workspace. In the case that a change in orientation is commanded by motion of part of the surgeon input device, such as a further trigger, then the angle θ may be proportional to the angle through which that part of the surgeon input device has rotated, or the distance along which that part of the surgeon input device has linearly translated.
At step 503, the control system compares θ to θmax. θmax is the maximum value of θ. In other words, θmax is the maximum angle between the longitudinal axis 401 of the articulated coupling and the end effector. θmax may be a function of the opening angle of the end effector elements ϕ. Alternatively, or additionally, θmax may be a function of the maximum rotational angle αmax of the furthest end effector element. For example,
αmax=αmax−ϕ/2 (equation 1)
The control system determines whether θ>θmax If θ≤θmax, then controlling the end effector elements to rotate such that the angle between the longitudinal axis 401 of the articulated coupling and the end effector is θ will not cause the opening angle of the end effector elements to start closing. Thus, if θ≤θmax, then at step 504, the control system drives the first and second end effector elements to rotate such that the angle between the longitudinal axis 401 of the articulated coupling and the end effector is θ. For example, the angle between the longitudinal axis 401 of the articulated coupling and the bisecting axis 404 is θ.
If, at step 503, the control system determines that θ>θmax, then controlling the end effector elements to rotate such that the angle between the longitudinal axis 401 of the articulated coupling and the end effector is θ will cause the opening angle of the end effector elements to start closing. Thus, instead, at step 505, the control system drives the first and second end effector elements to rotate such that the angle between the longitudinal axis 401 of the articulated coupling and the end effector is θmax. For example, the angle between the longitudinal axis 401 of the articulated coupling and the bisecting axis 404 is θmax.
Meanwhile, the control system determines to drive an opening angle ϕ between the first and second end effector elements. At step 506, in response to the command to open the end effector elements, the control system determines an opening angle ψ between the first and second end effector elements. Specifically, ψ is the angle between the longitudinal axis of the first end effector element 402 and the longitudinal axis of the second end effector element 403. The angle ψ is that determined to effect the opening angle between the end effector elements commanded by the surgeon input device. The angle ψ may be proportional to the rotational position of the trigger relative to the body of the surgeon input device once the trigger has been moved to effect the command of step 501.
At step 507, the control system compares ψ to ϕmax. The control system determines whether ψ>ϕmax. If ψ≤ϕmax, then at step 508, the control system drives the first and second end effector elements to rotate such that the angle between the longitudinal axes 402 and 403 of the end effector elements ϕ=ψ.
If at step 507, the control system determines that ψ>ϕmax, then at step 509, the control system drives the first and second end effector elements to rotate such that the angle between the longitudinal axes 402 and 403 of the end effector elements ϕ=ϕmax.
On
Performed in concert means that the control system determines the forces to be applied to the first pair of driving elements A1, A2 and the forces to be applied to the second pair of driving elements B1, B2 so as to cause both (i) the end effector to be driven to θ or θmax, and (ii) the opening angle to be driven to ϕ (i.e. ψ or ϕmax).
In response to the command to change the orientation of the end effector, the control system may also determine an angle Ω between the longitudinal axis 206 of the shaft 202 and the longitudinal axis 401 of the articulated coupling 203. The angles θ and Ω are determined to together effect the change in orientation commanded by the surgeon input device. For example, the combined angle θ+Ω may be proportional to the angle through which the surgeon input device has been rotated in its workspace. In this scenario, at step 510, the control system drives the third pair of driving elements C1, C2 so as to cause the supporting body 213 and hence the end effector 201 to rotate about the pitch axis 205 by the angle Ω.
After the end effector elements and/or supporting body have been driven to the angles described with reference to step 510, the control loop may repeat. In other words, a further command may be received by the control system to change the orientation of the end effector and open the end effector elements at step 501. In this case, the method described above repeats. Alternatively, a further command may be received by the control system to increase the opening angle between the end effector elements at step 511. For example, the trigger of the surgeon input device may have been rotated further away from the body of the surgeon input device. No command is received from the surgeon input device to change the orientation of the end effector. If at step 510, the end effector had been driven to θmax, then the furthest end effector element 210 is already at the maximum rotation angle αmax that it can sustain at the current opening angle of ϕ.
In response to the further command at step 511, at step 512 the control system determines ϕ′. ϕ′ is an opening angle between the first and second end effector elements. ϕ′ is determined to effect the opening angle between the end effector elements commanded by the surgeon input device at step 511. The angle ϕ′ may be proportional to the rotational position of the trigger relative to the body of the surgeon input device once the trigger has been moved to effect the command of step 511.
Then, at step 513, the control system determines θmax′. θmax′ is the maximum angle between the longitudinal axis of the articulated coupling and the end effector which enables the opening angle ϕ′ to be sustained. θmax′ may be a function of the opening angle of the end effector elements ϕ′. Alternatively, or additionally, θmax′ may be a function of the maximum rotational angle αmax of the furthest end effector element. For example,
θmax′=αmax−ϕ′/2 (equation 2)
Then, at step 514, the control system drives the end effector elements to rotate such that (i) the angle between the longitudinal axis of the articulated coupling and the end effector is θmax′, and (ii) the opening angle between the first and second end effector elements is ϕ′. Thus, in practice, the furthest end effector element 210 maintains its rotational position at αmax, and the closest end effector element 209 is driven to rotate towards the longitudinal axis of the articulated coupling 401, thereby achieving the desired opening angle ϕ′.
As a numerical example, consider a case where αmax=70°. At step 508, the opening angle of the end effector elements is driven to ϕ=50°. Thus, using equation 1, θmax=45°. At step 510, the end effector is driven to θmax=45°. Thus, the individual end effector elements are at 20° and 70° to the longitudinal axis 401 of the articulated coupling. At step 511, the control system receives a command from the surgeon input device to open the end effector elements to an opening angle of ϕ′=60°. Since αmax=70°, using equation 2, θmax′=40°. Thus, the individual end effector elements are at 10° and 70° to the longitudinal axis 401 of the articulated coupling.
Thus, the control method of
The steps illustrated in the control method of
The end effector may take any suitable form. For example, the end effector could be a pair of curved scissors, an electrosurgical instrument such as a pair of monopolar scissors, a needle holder, a pair of jaws, or a fenestrated grasper.
The robot described herein could be for purposes other than surgery. For example, the port could be an inspection port in a manufactured article such as a car engine and the robot could control a viewing tool for viewing inside the engine.
The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1915270.1 | Oct 2019 | GB | national |
