Pre-defined poses

Abstract

Discloses is a surgical robotic system comprising: a plurality of robots, the robots being physically independent to each other, each robot having a base, and an arm extending from the base to an interface for engaging an instrument, the arm comprising a plurality of joints whereby the arrangement of the arm can be altered, for each joint the robot comprising a driver configured to drive the joint to move; and a control unit configured to receive control inputs and control the drivers in dependence on those control inputs, the control unit being configured to: receive a selection control input; select a pre- defined pose of a plurality of pre-defined poses for one of the robot arms in dependence on the selection control input; and control the drivers to move the robot arm from an initial pose so that the robot arm is arranged in the pre-defined pose.

Description

[0001] PRE-DEFINED POSES

[0002] This invention relates to controlling the motion of robot arms, in particular surgical robot arms.

[0003] Background

[0004] Figure 1 illustrates multiple robots 101 , 102, 103 operating in a common workspace. In this example, the robots are surgical robots being used to perform an operation on a patient 104. Each robot comprises a base connected to a surgical instrument via a flexible arm. The robots are controlled remotely, in this case by a surgeon. The surgeon is located at a surgeon console 200, shown in figure 2. The surgeon manipulates hand controllers 201 , 202. A control system converts the movement of the hand controllers into control signals to move the arm joints and / or instrument end effector of a surgical robot. More than one robot may move at the same time.

[0005] Before certain actions, it can be beneficial to put the robot arms in a certain pose. For example, certain poses can have an improved range of motion for subsequent movements of the robot arm joints during surgery compared to other poses. Putting the robot arms in the certain pose is often done manually. The robot arms may be physically pushed by a member of a bedside team causing an external force on the robot arm. The external force may be measured by sensors at the joints. The sensor readings may be used to control the robot arm to comply with the external force. Controlling the movement of the robot arm manually in this way can be difficult to precisely put the robot arm in the certain pose. Additionally, the control system of the robot arm decides how to adapt the pose of the robot arm so that the position of the end effector complies with the external force. Put another way, the beside team cannot dictate the pose of the robot arm, only the position of the end effector. The control system dictates the pose of the robot arm so that the end effector position complies with the external force. As such, setting a certain pose by external forces can be difficult.

[0006] A similar situation can occur when the surgeon console is used to put the robot arms in a certain pose. The control system of the robot arm decides how to adapt the pose of the robot arm so that the position of the end effector complies with the inputs form the surgeon console. Put another way, the surgeon cannot dictate the pose of the robot arm, only the position of the end effector. The control system dictates the pose of the robot arm so that the end effector position complies with the inputs from the surgeon console. As such, setting a certain pose of the robot arm by the surgeon console can be difficult.

[0007] Additionally, operating robot arms in a common workspace leads to a risk of those robot arms colliding with each other. This is particularly likely in a compact common workspace where the operational area of one robot significantly overlaps the operational area of another robot. The initial pose of the robot arms at the start of surgery can have an impact on the likelihood of collision.

[0008] Further, mounting an instrument to the robot arm can cause forces to be applied on the arm, both from the weight of the instrument and from the force to engage the instrument with the robot arm. The drivers in the robot arm joints can be stronger or weaker in certain directions. Mounting the instrument when the forces act against the weaker direction of the driver can cause damage to the driver.

[0009] There is a need for a control system for setting the robot arm in advantageous poses.

[0010] Summary

[0011] According to a first aspect of the present invention there is provided a surgical robotic system. The system comprises a plurality of robots, the robots being physically independent to each other, each robot having a base, and an arm extending from the base to an interface for engaging an instrument, the arm comprising a plurality of joints whereby the arrangement of the arm can be altered, for each joint the robot comprising a driver configured to drive the joint to move; and a control unit configured to receive control inputs and control the drivers in dependence on those control inputs. The control unit is configured to: receive a selection control input; select a pre-defined pose of a plurality of pre-defined poses for one of the robot arms in dependence on the selection control input; and control the drivers to move the robot arm from an initial pose so that the robot arm is arranged in the pre-defined pose. In some implementations, one or more of the drivers may be asymmetrical rated load drivers. Each asymmetrical rated load driver may have a first rated load in a first direction of rotation of the joint and may have a second rated load in a second direction of rotation of the joint. The first rated load may be higher than the second rated load.

[0012] In some implementations, in the pre-defined pose, the robot arm may be arranged such that when the instrument is attached the weight of the instrument causes a torque that acts against the first direction of rotation of a joint that is driven by an asymmetrical rated load driver.

[0013] In some implementations, in the pre-defined pose, the robot arm may be arranged such that a force acting in the instrument engagement direction of the interface causes a torque that acts against the first direction of rotation of a joint that is driven by an asymmetrical rated load driver.

[0014] In some implementations, the robot arm may comprise a wrist proximal of the interface. The wrist may comprise a pitch joint. The wrist may comprise a yaw joint. The axis of the pitch joint may intersect the axis of the yaw joint.

[0015] In some implementations, pitch joint may be driven by an asymmetrical rated load driver and / or the yaw joint is driven by an asymmetrical rated load driver.

[0016] In some implementations, in the pre-defined pose, the robot arm may be arranged such that when the instrument is attached the weight of the instrument causes a torque that acts against the first direction of rotation of the pitch joint driven by an asymmetrical rated load driver.

[0017] In some implementations, in the pre-defined pose, the robot arm may be arranged such that when the instrument is attached the weight of the instrument causes a torque that acts against the first direction of rotation of the yaw joint driven by an asymmetrical rated load driver. In some implementations, in the pre-defined pose, the robot arm may be arranged such that a force acting in the instrument engagement direction of the interface causes a torque that acts against the first direction of rotation of the pitch joint driven by an asymmetrical rated load driver and / or acts against the first direction of rotation of the yaw joint driven by an asymmetrical rated load driver.

[0018] In some implementations, the pre-defined pose may be one of a subset of the plurality of pre-defined poses in which the robot arm is arranged such that each of the joints of the robot arm are positioned within a threshold range of motion of the total range of motion of the joint.

[0019] In some implementations, in the pre-defined pose, the robot arm may be arranged such that each of the joints of the robot arm are positioned within 10% to 90% of total range of motion of the joint.

[0020] In some implementations, in the pre-defined pose, the robot arm may be arranged such that each of the joints of the robot arm are positioned within 40% to 60% of total range of motion of the joint.

[0021] In some implementations, the control unit may be configured to receive the relative orientations of each of the plurality of robot arms. In some implementations, the control unit may be configured to receive the arrangements of each of the plurality of robot arms.

[0022] In some implementations, the control unit may be configured to control the drivers to move the robot arm so that the robot arm is arranged in the pre-defined pose along a route which does not cause a clash between the robot arm and one of the other plurality of robot arms.

[0023] In some implementations, the pre-defined pose may be one of a subset of the plurality of pre-defined poses in which the robot arm is arranged such that each of the joints of the robot arm are positioned such that, in the pre-defined pose, the robot arm does not cause a clash between the robot arm and one of the other plurality of robot arms. In some implementations, the pre-defined pose may be one of a subset of the plurality of pre-defined poses in which the robot arm is arranged such that each of the joints of the robot arm are positioned such that subsequent movements of the joints within a threshold movement range do not cause a clash between the robot arm and one of the other plurality of robot arms.

[0024] In some implementations, the pre-defined pose may be one of a subset of the plurality of pre-defined poses that are optimised in dependence on data from the surgical robotic system.

[0025] In some implementations, the control unit may be configured to receive data from the surgical robotic system.

[0026] In some implementations, the control unit may be configured to select a pre-defined pose of a plurality of pre-defined poses for the robot arms in dependence on the data from the surgical robotic system.

[0027] In some implementations, data from the surgical robotic system may comprise one or more of: the position of the robot arm relative to the other robot arms of the plurality of robot arms; the position robot arm relative to the position of an operating bed; the characteristics of a patient; and the characteristics of a surgical procedure.

[0028] In some implementations, the characteristics of the patient comprise one or more of: the height of the patient; the BMI of the patient; the gender of the patient; and the orientation of the patient on the operating bed.

[0029] In some implementations, the control unit is configured to operate in a surgical mode in which the control unit is configured to control the movement of the robot arm in dependence on inputs from a surgical console. In some implementations, the control unit is configured to operate in a compliant mode in which the control unit is configured to control the movement of the robot arm in dependence on inputs from torque sensors measuring torque on the joints due to external forces on the robot arm. In some implementations, in the surgical mode the instrument may be engaged with the interface.

[0030] In some implementations, the initial pose may be a sleep pose in which the arrangement of the robot arm minimises the external volume of the robot arm.

[0031] In some implementations, the pre-defined pose may be a wake pose in which the arrangement of the robot arm increases the external volume of the robot arm compared to the sleep pose.

[0032] In some implementations, the pre-defined pose may be the start pose of the surgical mode. In some implementations, the pre-defined pose may be the start pose of the compliant mode.

[0033] In some implementations, the initial pose may be a final pose of the surgical mode. In some implementations, the initial pose may be a final pose of the compliant mode.

[0034] In some implementations, the pre-defined pose comprises one of: a drape pose in which the arrangement of the robot arm forms a substantially straight line; a horseshoe pose in which the arrangement of the robot arm forms a horseshoe shape; a C-shape pose in which the arrangement of the robot arm forms a C-shape; and a Z-shape pose in which the arrangement of the robot arm forms a Z-shape.

[0035] In some implementations, the control unit may be configured to: receive a further selection control input; select a further pre-defined pose of a plurality of pre-defined poses for one of the robot arms in dependence on the further selection control input; and control the drivers to move the robot arm from the pre-defined pose so that the robot arm is arranged in the further pre-defined pose.

[0036] In some implementations, the control unit may be configured to receive the selection control input from a user input device. The user device may be located on one or more of: the base of the robot; the arm of the robot; a surgeon console; and a mobile device connected to the surgical robotic system. In some implementations, the user input device may comprise a button. In some implementations, in response to the user input device being continuously activated, the control unit may be configured to control the drivers to move the robot arm from the initial pose so that the robot arm is arranged in the pre-defined pose. In some implementations, the control unit may be configured to stop controlling the drivers to move the robot arm if the user input device is deactivated before the robot arm is arranged in the pre-defined pose.

[0037] In some implementations, in response to the user input device being continuously activated after the robot arm is in the pre-defined pose, the control unit may be configured to control the drivers to move the robot arm from the pre-defined pose so that the robot arm is arranged in the further pre-defined pose. In some implementations, the control unit may be configured to stop controlling the drivers to move the robot arm if the user input device is deactivated before the robot arm is arranged in the further pre-defined pose.

[0038] In some implementations, the control unit may be configured to output a user output once the robot arm is in the pre-defined pose.

[0039] In some implementations, the user output may comprise one or more of: an audible output; a visible output; and a physical output.

[0040] In some implementations, in the surgical mode, the control unit may be configured such that all the drivers are operable to move all the joints of the robot arm.

[0041] According to a second aspect of the present invention there is provided a method for controlling a surgical robotic system, the surgical robotic system comprising: a plurality of robots, the robots being physically independent to each other, each robot having a base, and an arm extending from the base to an interface for engaging an instrument, the arm comprising a plurality of joints whereby the arrangement of the arm can be altered, for each joint the robot comprising a driver configured to drive the joint to move; and a control unit configured to receive control inputs and control the drivers in dependence on those control inputs; the method comprising steps of, the control unit: receiving a selection control input; selecting a pre-defined pose of a plurality of pre- defined poses for one of the robot arms in dependence on the selection control input; and controlling the drivers to move the robot arm from an initial pose so that the robot arm is arranged in the pre-defined pose.

[0042] Brief Description

[0043] The present invention will now be described by way of example with reference to the accompanying drawings. In the drawings:

[0044] Figure 1 illustrates a patient being operated on by a robotic system comprising three surgical robots.

[0045] Figure 2 illustrates a surgeon console.

[0046] Figure 3 illustrates a schematic diagram of a robotic system.

[0047] Figure 4 illustrates a robot.

[0048] Figure 5 illustrates the steps of a control unit of a first embodiment.

[0049] Figure 6 illustrates the steps of a control unit of a second embodiment.

[0050] Figure 7a illustrates a robot arm in a straight arrangement. Figure 7b illustrates a robot arm in a horseshoe arrangement. Figure 7c illustrates a robot arm in a C-shaped arrangement. Figure 7d illustrates a robot arm in a Z-shaped arrangement.

[0051] Figure 8 illustrates gears of a driver of the robot arm.

[0052] Detailed Description

[0053] The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of a particular application. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

[0054] The present invention relates to controlling a robot arm to be arranged in a pre-defined pose. Controlling the robot arm to adopt a pre-defined pose may provide an easy and efficient means for putting the robot arm in a certain pose. This can avoid potential difficulties with attempting to set a certain pose through an external force being applied to the robot arm, or through inputs from the hand controllers of the surgeon console.

[0055] The following description relates to a robotic system comprising a plurality of robots and a control unit. The control unit may control the movement of the robot arms. The control unit may receive control inputs and control drivers of the robot arm in dependence on the control input to move the robot arms. The control inputs may also enable selection of a pre-defined pose, and the robot arm may be moved to the selected pre-defined pose.

[0056] The following examples relate to a surgical robotic system 300. The surgical robotic system 300 may comprise a plurality of surgical robots 301 , 302. With reference to Figure 3, the surgical robotic system 300 may comprise two surgical robots 301 , 302. The robots 301 ,302 may be physically independent to each other. In other words, the robots 301 , 302 may contact one another. The robots 301 , 302 may be remote from one another. The robots 301 , 302 may not share a common base. That said, the robots 301 , 302 may be located on the same floor, such as the floor of the operating theatre. The surgical robots 301 , 302 may be driven by a control unit 303. The control unit 303 may receive inputs 307 from a surgeon’s console 304, including inputs from first and second hand controllers 305, 306. The control unit may receive other inputs 307 from the surgeon console, such as foot pedal(s) inputs, button inputs, voice recognition inputs, gesture recognition inputs, eye recognition inputs etc. The control unit 303 may also receive inputs 308 from the surgical robots 301 , 302. These inputs may include sensory data from position sensors and torque sensors located on the robot arm joints 405. The control unit 303 may receive other inputs 308 from each robot 301 , 302, such as force feedback, data from the surgical instrument etc. The control unit 303 may control the drive of the robots 301 , 302 in response to the inputs it receives from the robots 301 , 302 and the surgeon’s console 304. The control unit 303 may comprise a processor 309 and a memory 310. The memory stores, in a non-transient way, software code that can be executed by the processor to cause the processor to control the drivers in the manner described herein. The control unit 303 may be integrated in the robots 301 , 302. The control unit 303 may be integrated in the surgeon console 304. The control unit 303 may be a separate unit to the robots 301 , 302 and the surgeon console 304.

[0057] Each robot 301 , 302 may be of the form 400 illustrated in figure 4. The robot 301 ,302 may comprise a base 401 which is fixed in place when a surgical procedure is being performed. Each robot 301 , 302 may have its own base 401 . The robots 301 , 302 may be physically independent to each other by having separate bases 401 . Suitably, the base 401 may be mounted to a chassis. That chassis may be a cart, for example a bedside cart for mounting the robot 301 , 302 at bed height. Alternatively, the chassis may be a ceiling mounted device, or a bed mounted device.

[0058] An arm 402 may extend from the base 401 of the robot 301 , 302 to an interface 403 for a surgical instrument 404. The arm 402 may be flexible. The arm 402 is articulated by means of multiple flexible joints 405 along its length. In between the joints 405 may be rigid arm members 406. The arm in Figure 4 has eight joints 405. The arm 402 may comprise a different number of joints 405 depending on the implementation. The joints 405 include one or more roll joints (which have an axis of rotation along the longitudinal direction of the arm members on either side of the joint), one or more pitch joints (which have an axis of rotation transverse to the longitudinal direction of the preceding arm member), and one or more yaw joints (which also have an axis of rotation transverse to the longitudinal direction of the preceding arm member and also transverse to the rotation axis of a co-located pitch joint). However, the robot arm 402 could be jointed differently. For example, the robot arm 402 may have fewer or more joints 405. The robot arm 402 may include joints 405 that permit motion other than rotation between respective sides of the joint, for example a telescopic joint. The robot 301 , 302 comprises a set of drivers 407, each driver 407 drives one or more of the joints 405. The interface 403 may enable the surgical instrument 404 to be releasably engaged to the distal end of the arm 402. The surgical instrument 404 may engage with the interface 403 in a direction transverse to the plane of the interface 403. The surgical instrument 404 may have a linear rigid shaft and a working tip at the distal end of the shaft. The working tip may comprise an end effector for engaging in a medical procedure. The surgical instrument 404 may be configured to extend linearly parallel with the rotation axis of the terminal joint of the arm. For example, the surgical instrument 404 may extend along an axis coincident with the rotation axis of the terminal joint of the arm. The surgical instrument 404 could be, for example, a cutting, grasping, or cauterising device. The surgical instrument 404 can also be an endoscope.

[0059] The robot arm 402 may comprise a series of sensors 408, 409. The sensors may comprise, for each joint, a position sensor 408 for sensing the position of the joint, and a torque sensor 409 for sensing the applied torque about the joint’s rotation axis. One or both of the position and torque sensors for a joint may be integrated with the motor for that joint. The outputs of the sensors may be passed to the control unit 303 where they form inputs for the processor 309.

[0060] The control unit 303 may receive a selection control input. The selection control input may indicate a pose to which the robot arm 402 is required to move. The selection control input may be inputted by a user of the surgical robotic system 300. The selection control input may be inputted by another component of the surgical robotic system 300. There may be a plurality of pre-defined poses into which the robot arm 402 can be controlled to move. The pre-defined poses may be stored in the memory of the control unit 303. The pre-defined poses may be inputted to the control unit 303 by a user. The pre-defined poses may be inputted to the control unit 303 by a user before the robot 301 , 302 is used. The pre-defined poses may be generated by the control unit 303. The pre-defined poses may be generated by the control unit 303 during operation of the robot 301 , 302. The pre-defined poses may be categorised for different uses. The pre-defined poses may have certain advantages in different situations. The pre-defined pose may define positions of each of the joints 405 and members 406 of the robot arm 402. The pre-defined pose may dictate the angles of each of joints

[0061] 405. The angles of the joints 404 may dictate the relative positions of the members

[0062] 406. The pre-defined pose may define the shape which the robot arm 402 adopts. The drivers 407 may drive the robot arm 402 to the pre-defined pose. The robot arm 402 may move to the pre-defined pose along a route. Each of the joints 405 and members of the robot arm 402 may follow the route. The route may define the position over time of all parts of the robot arm 402. The collective movement of the joints 405 may allow the robot arm 402 to move between poses. Each of the joints 405 may move with respective angular velocities, which might vary over time, such that the robot arm 402 moves to the pre-defined pose.

[0063] The control unit 303 may select a pre-defined pose of the plurality of pre-defined poses. The control unit 303 may select the pre-defined pose of the plurality of predefined poses in dependence on the selection control input. The selection control input may directly request a certain pre-defined pose of the plurality of pre-defined poses. For example, the user may ask for a certain pose, and the control unit 303 may select the correct pre-defined pose. Alternatively, the selection control input may comprise data based on which the control unit 303 may select one the plurality of pre-defined poses. For example, the selection control input may comprise data about the patient, such as their height, and the control unit 303 may select one the plurality of pre-defined poses based on this data.

[0064] The control unit 303 may control the drivers 407 to move the robot arm 402. The control unit 303 may control the drivers 407 to move the robot arm 402 into the predefined pose. The robot arm 402 may start in an initial pose. The robot arm 402 may move from the initial pose to the pre-defined pose.

[0065] The control unit 303 may be configured to operate the robot arm 402 in different modes. The control unit 303 may be configured to change the operating mode. The control unit 303 may change the operating mode in response to an input to the control unit 303. The input may be received from the robot 301 , 302, the surgeon console 304, or another component. The control unit 303 may operate in a surgical mode. In the surgical mode, movements of the robot arm 402 may be controlled in dependence on inputs from the surgical console 304. The surgeon may move the hand controllers 305, 306 which causes an input from the surgeon console 304 to the control unit 303. The control unit 303 may control the robot arm 402 based on the inputs from the surgeon console 304. In the surgical mode, the instrument 404 may be engaged with the interface 403. The inputs from the surgeon console 304 may also control the instrument 404. In the surgical mode, the control unit 303 may be configured so that all the drivers 407 of the robot arm 402 are operable to move all the joints 405 of the robot arm 402. In other words, in the surgical mode, the surgeon may have access to controlling all parts of the robot arm 402. This may differ from a remote centre of motion robot arm 402 in which part of the arm 402 (a proximal group of joints 405 and members 406) is fixed, and part of the arm 402 (a distal group of joints 405 and members 406) is controllable in an operative, such as a surgical, mode.

[0066] The control unit 303 may operate in a compliant mode. In the compliant mode, movements of the robot arm 402 may be controlled in dependence on inputs from the torque sensors 409. The torque sensors 409 may measure the torques on the joints 405 due to external forces on the robot arm 402. The torque sensors 409 may measure the total torque, and the control unit 303 may subtract the torque due to the robot arm 402 itself to calculate the torques due to the external forces acting on the robot arm 402. The torque due to the robot arm 402 itself may include the gravitational force on the robot arm members 406, the centripetal forces on the robot arm members 406, friction in the joints 405 etc. Based on the external forces on the robot arm 402, the control unit 303 my control the drivers 407 to move the robot arm 402. In the compliant mode, the robot arm 402 movements by the drivers 407 may simulate the movements that would have happened due to the external forces on the robot arm 402. A user may physically push the robot arm 402 with a force, and in response, the robot arm 402 may move as if it had been pushed to move.

[0067] The control unit 303 may operate in a pre-defined pose mode. In the predefined pose mode, movements of the robot arm 402 may be controlled in dependence on the selection control input. The control unit 303 may change between modes based on inputs from the surgeon console 304, or other parts of the surgical robotic system 303. For example, when the surgeon has finished controlling the robot arm 402 during surgery, the surgeon may provide an input to end the surgical mode. Similarly, once the robot arm 402 is in the correct position (such as a pre-defined position), the surgeon may apply an input to start the surgical mode. The same may apply to the compliant mode.

[0068] Figure 5 illustrates a first example 500 of how the control unit 303 may change operating modes. Steps 501 to 504 may be in the predefined pose mode. Step 505 may be in the surgical mode. Step 506 may be in the compliant mode.

[0069] The robot arm 402 may start in the sleep pose 501 . The sleep pose 501 may be the initial pose of the robot arm 402. In the sleep pose 501 , the arrangement of the robot arm 402 may be such that the external volume of the robot arm 402 is minimised. In other words, the volume defined by the outmost points of the robot arm 402 may be minimised in the sleep pose 501 . In the sleep pose 501 , the arrangement of the robot arm 402 may be such that the footprint of the robot arm 402, and optionally the base 401 , is minimised. In other words, when viewed from above, the area covered by the robot arm 402, and optionally the base 401 , may be minimised in the sleep pose 501 . The sleep pose 501 may be a folded configuration of the robot arm 402. In the case of the robot arm 402 in Figure 4, the sleep pose 501 may comprise each of the members 406 being as close to one another as possible. Each of the joints 405 may be at one end of the range of motion.

[0070] The robot arm 402 may transition into the awake pose 502. The robot arm 402 may transition into the awake pose 502 from the sleep pose 501 . The awake pose 502 may be one of the pre-defined poses. Alternatively, the awake pose 502 may be the initial pose of the robot arm 402. In the awake pose 502, the arrangement of the robot arm 402 may be such that the external volume of the robot arm 402 is greater than in the sleep pose 501 . The robot arm 402 may slightly unfold from the sleep pose 501 to the awake pose 502. The robot arm 402 may be easier to control from the awake pose 502. For example, the joints 405 may be further from the end of the range of motion, such that the joints 405 move in either direction more freely. The members 406 may be further apart such that the members 406 are easier to grab and push in a compliant mode.

[0071] The robot arm 402 may transition into the pre-defined pose 503. The robot arm 402 may transition to the pre-defined pose from the sleep pose 501 or the awake pose

[0072] 502.

[0073] Optionally, the robot arm 402 may transition into one or more further pre-defined poses 504. The robot arm 402 may move between a plurality of different pre-defined poses

[0074] 503, 504. The control unit 303 may control the robot arm 402 to cycle through the different pre-defined poses 503, 504. The control unit 303 may receive a further selection control input. The further selection control input may be as described herein for the selection control unit. The control unit 303 may select a further pre-defined pose 504 in dependence on the further selection input. The selection of the further pre-defined pose 504 may be as described herein for the predefined pose 503. The control unit 303 may control the drivers 407 to move the robot arm 402 from the predefined pose 503 to the further pre-defined pose 504.

[0075] From the pre-defined pose 503 (or the further pre-defined pose 504), the robot arm 402 may transition into the surgical mode 505. The pre-defined pose 503 may be the starting position of the surgical mode 505. The surgeon may take control of the robot arm 402, and move the robot arm 402 from the pre-defined pose 503 at the start of the surgical mode 505. The instrument 404 may be fitted in the pre-defined pose 503. In this way, the instrument 404 may be fitted at the start of the surgical mode 505.

[0076] From the pre-defined pose 503 (or the further pre-defined pose 504), the robot arm 402 may transition into the compliant mode 506. The pre-defined pose 503 may be the starting position of the compliant mode 506. The bedside team may physically apply a force to the robot arm 402, and move the robot arm 402 from the pre-defined pose 503 at the start of the compliant mode 506.

[0077] Figure 6 illustrates a second example 600 of how the control unit 303 may change operating modes. Steps 503 to 504 may be in the pre-defined pose mode. Step 505 may be in the surgical mode. Step 506 may be in the compliant mode. The control unit 303 may start in the surgical mode 505. The surgeon may stop controlling the robot arm 402. The initial pose may be a final pose of the surgical mode 505. Alternatively, the control unit 303 may start in the compliant mode 506. The bedside team may stop physically applying a force to the robot arm 402. The initial pose may be a final pose of the compliant mode 506.

[0078] The robot arm may transition into the pre-defined pose 503. The robot arm 402 may transition to the pre-defined pose from the surgical mode 505 or the compliant mode 505.

[0079] Optionally, the robot arm 402 may transition into one or more further pre-defined poses 504. The robot arm 402 may move between a plurality of different pre-defined poses 503, 504. The control unit 303 may control the robot arm 402 to cycle through the different pre-defined poses 503, 504. The control unit 303 may receive a further selection control input. The further selection control input may be as described herein for the selection control unit. The control unit 303 may select a further pre-defined pose 504 in dependence on the further selection input. The selection of the further pre-defined pose 504 may be as described herein for the predefined pose 503. The control unit 303 may control the drivers 407 to move the robot arm 402 from the predefined pose 503 to the further pre-defined pose 504.

[0080] From the pre-defined pose 503 (or the further pre-defined pose 504), the robot arm 402 may transition into the surgical mode 505. The pre-defined pose 503 may be the starting position of the surgical mode 505. The surgeon may take control of the robot arm 402, and move the robot arm 402 from the pre-defined pose 503 at the start of the surgical mode 505. The instrument 404 may be fitted to the robot arm 402 in the pre-defined pose 503. In this way, the instrument 404 may be fitted before the surgical mode 505 starts. Optionally, there may be a calibration mode before the surgical mode 505 starts. During the calibration mode, the control unit 303 may carry out port training.

[0081] From the pre-defined pose 503 (or the further pre-defined pose 504), the robot arm 402 may transition into the compliant mode 506. The pre-defined pose 503 may be the starting position of the compliant mode 506. The bedside team may physically apply a force to the robot arm 402, and the robot arm 402 may be driven in accordance with the external forces sensed at the torque sensors 409 from the pre-defined pose 503 at the start of the compliant mode 506.

[0082] Figures 7a to 7d are schematic representations of the robot arm 402 illustrated in Figure 4. Figures 7a to 7d show the three most distal members 406, three most distal joints 405a 405b, 405c, and the instrument 404.

[0083] Figure 7a shows the robot arm 402 in a straight arrangement. The straight arrangement may be known as the ‘drape pose’. The straight arrangement may make it easier for a surgical drape to be applied over the robot arm 402. The straight arrangement may help to ensure that the drape does not catch on the joints 405 and members 406 when being applied over the robot arm 402. In more detail, each of the joints 405 may be arranged generally at their centre of range of motion. Each of the members 406 may be generally in line with one another. The longitudinal axis of each member 406 may generally align with one another. The three most distal members 406 may be aligned. The longitudinal axis of the instrument 404 may intersect with the axis of the most proximal joint 405a shown. There may be further proximal joints 405 and members 406 depending on the structure of the robot arm 402. The further proximal joints 405 and members 406 may also have a straight arrangement. Alternatively, the further proximal joints 405 and members 406 may not have a straight arrangement. Figure 7a illustrates the robot arm 402 from above. The joints 405 and members 406 may also be straight from the side. The longitudinal axis of the members 406 may be coaxial. Alternatively, the joints 405 and members 406 may not be straight from the side.

[0084] Figure 7b shows the robot arm 402 in a horseshoe-shape arrangement. The horseshoe-shape arrangement may be known as the ‘horseshoe pose’. The horseshoe pose may provide a helpful position for inserting the instrument 404 into a patient when the robot arm 402 is located next to the patient. In particular, the most proximal joint 405a may be generally vertically aligned with the base of the robot 301 , 302, and the instrument 404 may be inserted into the patient. The horseshoe pose may also provide a high range of motion starting from the horseshoe pose. For example, there may be a high range of motion in the directions normally used during surgery from that position. The most proximal joint 405a may require the largest range of motion so as to move the more distal members 406 side to side. Movement of the more proximal joints 405a may have a smaller effect on the angle of the instrument 404 than the more distal joint 405c, and so moving the more proximal joints 405a may allow more precise movements. However, to control movements with the more proximal joints 405a, the range of motion may need to be greater. In more detail, middle joint 405b may be bent at an acute angle. The middle joint 405b may be at just less than 90 degrees. Distal joint 405c may be bent at an acute angle. The distal joint 405c may be at just less than 90 degrees. The middle joint 405b and the distal joint 405c may be bent in the same directions. The result is that the robot arm 402 may form a horseshoe-shape. There may be further proximal joints 405 and members 406 depending on the structure of the robot arm 402. The further proximal joints 405 and members 406 may also have a horseshoe arrangement. Alternatively, the further proximal joints 405 and members 406 may not have the horseshoe arrangement. Figure 7b illustrates the robot arm 402 from above. The joints 405 and members 406 may also be in a horseshoe arrangement from the side. Alternatively, the joints 405 and members 406 may not be in a horseshoe shape from the side. The joints 405 and members 406 may be straight from the side, or may take a different shape from the side. The shape from the side may depend on the height of the operating table compared to the robot 301 , 302.

[0085] Figure 7c shows the robot arm 402 in a C-shape arrangement. The C-shape arrangement may be known as the ‘C-shape pose’. The C-shape pose may provide a helpful position for inserting the instrument 404 into a patient when the robot arm 402 is located next to the patient. In particular, the most proximal joint 405a may be generally vertically aligned with the base of the robot 301 , 302, and the instrument 404 may be inserted into the patient. The C-shape pose may also provide a high range of motion starting from the C-shape pose. For example, there may be a high range of motion in the directions normally used during surgery from that position. The most proximal joint 405a may require the largest range of motion so as to move the more distal members 406 side to side. Movement of the more proximal joints 405a may have a smaller effect on the angle of the instrument 404 than the more distal joint 405c, and so moving the more proximal joints 405a may allow more precise movements. However, to control movements with the more proximal joints 405a, the range of motion may need to be greater. In more detail, middle joint 405b may be bent at about 90 degrees. Distal joint 405c may be bent at about 90 degrees. The middle joint 405b and the distal joint 405c may be bent in the same directions. The result is that the robot arm 402 may form a C-shape. There may be further proximal joints 405 and members 406 depending on the structure of the robot arm 402. The further proximal joints 405 and members 406 may also have a C-shape arrangement. Alternatively, the further proximal joints 405 and members 406 may not have the C-shape arrangement. Figure 7c illustrates the robot arm 402 from above. The joints 405 and members 406 may also be in a C-shape arrangement from the side. Alternatively, the joints 405 and members 406 may not be in a C-shape shape from the side. The joints 405 and members 406 may be straight from the side, or may take a different shape from the side. The shape from the side may depend on the height of the operating table compared to the robot 301 , 302.

[0086] The horseshoe pose and the C-shape pose may have similar arrangements with slightly different joint 405 angles. The horseshoe pose may be suitable for surgery where the instrument 404 needs to be straight on in the body. The C-shape pose may be suitable for surgery where the instrument 404 needs to be at an angle in the body.

[0087] Figure 7d shows the robot arm 402 in a Z-shape arrangement. The Z-shape arrangement may be known as the ‘Z-shape pose’. The Z-shape pose may provide a helpful position for inserting the instrument 404 into a patient when the robot arm 402 is located at the end of the patient (at the end or feet). In particular, the most proximal joint 405a may be generally vertically aligned with the base of the robot 301 , 302, and the instrument 404 may be inserted into the patient. The Z-shape pose may also provide a high range of motion starting from the Z-shape pose. For example, there may be a high range of motion in the directions normally used during surgery from that position. The most proximal joint 405a may require the largest range of motion so as to move the more distal members 406 side to side. Movement of the more proximal joints 405a may have a smaller effect on the angle of the instrument 404 than the more distal joint 405c, and so moving the more proximal joints 405a may allow more precise movements. However, to control movements with the more proximal joints 405a, the range of motion may need to be greater. In more detail, middle joint 405b may be bent at about 90 degrees. Distal joint 405c may be bent at about 90 degrees. The middle joint 405b and the distal joint 405c may be bent in opposite directions. The middle joint 405b and the distal joint 405c may instead be bent at acute angles. The result is that the robot arm 402 may form a Z-shape. There may be further proximal joints 405 and members 406 depending on the structure of the robot arm 402. The further proximal joints 405 and members 406 may also have a Z-shape arrangement. Alternatively, the further proximal joints 405 and members 406 may not have the Z-shape arrangement. Figure 7d illustrates the robot arm 402 from above. The joints 405 and members 406 may also be in a Z-shape arrangement from the side. Alternatively, the joints 405 and members 406 may not be in a Z-shape shape from the side. The joints 405 and members 406 may be straight from the side, or may take a different shape from the side. The shape from the side may depend on the height of the operating table compared to the robot 301 , 302.

[0088] The control unit 303 may receive the selection control input from a user input device. In this way, a user may be able to input the selection control input. The user may be able to select the pre-defined pose 503. The user may be able to have an input on the selection of the pre-defined pose 503.

[0089] The user input device may be located on the robot 301 , 302. The user input device may be located on the base 401 of the robot 301 , 302. The user input device may be located on the arm 402 of the robot 301 , 302. The location of the user input device may be located in a position on the robot 301 , 302 which is accessible by the bedside team. In this way, the bedside team may be able to input the selection control input while standing next to the robot base 401 . In this way, the robot arm 402 may be controllable into the pre-defined pose by somebody next to the robot 301 , 302.

[0090] The user input device may be located on the surgeon console 304. The user input device may be the surgeon console 304. In this way, the surgeon may be able to input the selection control input while at the surgeon console 304. In this way, the robot arm 402 may be controllable into the pre-defined pose by somebody next to the surgeon console 304. The surgeon console 304 may be remote from the robot 301 , 302. For example, the surgeon console 304 may be elsewhere in the operating room, or outside of the operating room. The robot arm 402 may be controllable into the pre-defined pose by somebody remote from the robot 301 , 302, such as on the other side of the operating room or outside of the operating room.

[0091] The user input device may be located on a mobile device. The user input device may be the mobile device. The mobile device may be connected to the surgical robotic system 300. The mobile device may be connected to the surgical robotic system 300 by a wireless or wired connection. The connection may be through the internet, Wi-Fi, Bluetooth etc. The mobile device may be a dedicated device for the surgical robotic system 300. For example, the mobile device may be a tablet computer which is part of the surgical robotic system 300. The mobile device may be a standard mobile device, such a mobile phone, tablet computer, laptop computer etc. The mobile device may run an app through which the selection control input may be sent from. In this way, a user may be able to input the selection control input while remote from the robot 301 , 302. In this way, the robot arm 402 may be controllable into the pre-defined pose by somebody away from the robot 301 , 302. The mobile device could be in the same operating room, or could be outside of the operating room.

[0092] The mobile device may ask for the user’s identity before the selection control input is sent. The mobile device may verify / authenticate the user’s identity before the selection control input is sent. The mobile device may only send the selection control input to the control unit 303 when the user is verified / authenticated. The user may log into an account on the mobile device before the selection control input can be sent. An account may be set up for each of the bedside staff and surgeons.

[0093] The selection control input may be the result of the user input device being activated and / or deactivated. In response to the user input device being continuously activated, the control unit 303 may control the drivers to move the robot arm 402 from the initial pose so that the robot arm 402 is arranged in the pre-defined pose 503. Optionally, the control unit 303 may stop controlling the drivers to move the robot arm 402 if the user input device is deactivated before the robot arm 402 is arranged in the pre-defined pose 503. In this way, the robot arm 402 may be prevented from moving if there is not a continuous input from a user. Similarly, in response to the user input device being continuously activated after the robot arm 402 is in the pre-defined pose, the control unit 303 may control the drivers to move the robot arm 402 from the pre-defined pose so that the robot arm 402 is arranged in the further pre-defined pose 504. Optionally, the control unit 303 may stop controlling the drivers to move the robot arm 402 if the user input device is deactivated before the robot arm 402 is arranged in the further pre-defined pose. The same my apply for a moving to a plurality of pre-defined poses 504.

[0094] Continuous activation may require constant input to the user input device. Continuous activation may require input within certain time intervals. For example, input may be required every second. Activation of the user input device may comprise a user contacting the user input device. Deactivation of the input device may comprise a user stopping contacting the user input device. Continuous activation may require constant contacting of the user input device. The activation and deactivation may comprise other input means from a user, such as voice command input.

[0095] As the robot arm 402 moves from the initial pose to the pre-defined pose 503, the robot arm 402 may move along a route. As the robot arm 402 moves from the predefined pose 503 to the further pre-defined pose 504, the robot arm 402 may move along another route. As the user input device is activated, the robot arm 403 may move along one of the routes. If the user input device is deactivated, the robot arm 402 may stop at a point along the route. If the user input device is re-activated, the robot arm 402 may continue to move along the route. Each of the joints 405 and members of the robot arm 402 may follow the route. The route may define the position over time of all parts of the robot arm 402. The collective movement of the joints 405 may allow the robot arm 402 to move between poses. Each of the joints 405 may move with respective angular velocities, which might vary over time, such that the robot arm 402 moves to the pre-defined pose 504. If the robot arm 402 stops along the route due to deactivation, each of the joints 405 may each be in respective positions along the route.

[0096] The user input device may comprise a button. The button may be a physical button. The physical button may be located on the robot 301 , 302 or surgeon console 304. The button may be a virtual button. For example, the button may be located on a touch screen, such as the touch screen of the mobile device. The user input device may also comprise a dial or sliding input. The selection control input may be the result of a user pressing and optionally holding the user input device, such as the button, dial, or sliding input. For example, a single press of the user input device may control the robot arm 402 to move to a pre-defined pose 503. Alternatively, a continuous holding of the user input device may be required to move the robot arm 402 to the pre-defined pose 503. The user input device may need to be contacted and held in contact until the robot arm 402 has moved to the predefined pose 503. If the user input device is released before the robot arm is arranged in the pre-defined pose 503, then the control unit 303 may stop controlling the drivers to move. In which case, the robot arm 402 may stop in an arrangement before reaching the pre-defined pose 503. This may be beneficial in surgical implementations. Under the safety requirements for surgical robots, there must be a continuous input for any movements of the robot arm 402. Thus, to move the robot arm 402 to the pre-defined pose 503, the user input device may need to be continuously contacted until the robot arm 402 is in the pre-defined pose 503.

[0097] Once the robot arm 402 is in a pre-defined pose 503, the control unit 303 may output a user output. In this way, the user may know that the robot arm 402 is in a pre-defined pose 503. The user output may be an audible output. For example, the control unit 303 may cause a sound, such as a ‘bing’, when the robot arm 402 reaches a predefined pose 503. The user output may be a visible output. For example, the control unit 303 may cause a light, such as a flash, when the robot arm 402 reaches a predefined pose 503. The user output may be a physical output. For example, the control unit 303 may cause a force, such as a haptic feedback from a hand controller, to the user when the robot arm 402 reaches a pre-defined pose 503.

[0098] The following takes Figures 5 and 6 as examples, and using the example of a physical button. The same may apply to other user input devices, such as dials, and sliding inputs.

[0099] Referring to Figure 5, the robot arm 402 may initially be in the sleep pose 501 . The user may press and hold the button, and the robot arm 402 may move to the awake pose 502. If the button is released once the robot arm 402 reaches the awake pose 502, the robot arm 402 may stay in the awake pose. If the button is not released once the robot arm 402 reaches the awake pose 502, the robot arm 402 may continue to move into another pose. The robot arm 402 may or may not move straight after the awake pose 502 is reached. For example, the robot arm 402 may stay in the awake pose 502 for a period of time before continuing to move. The user may press and hold the button again, and the robot arm 402 may move to the pre-defined pose 503. If the button is released once the robot arm 402 reaches the pre-defined pose 503, the robot arm 402 may stay in the pre-defined pose 503. If the button is not released once the robot arm 402 reaches the pre-defined pose 503, the robot arm 402 may continue to move into another pose. The robot arm 402 may or may not move straight after the pre-defined pose 503 is reached. For example, the robot arm 402 may stay in the predefined pose 503 for a period of time before continuing to move. The control unit 303 may continue the same process for a plurality of further pre-defined poses 504. The robot arm 402 may cycle through each of the pre-defined poses 504. The number of further pre-defined poses 504 may be varied depending on how many options are required. Once the final pre-defined pose 503, 504 is selected, the control unit 303 may initiate the surgical mode 505 or the compliant mode 506 in response to a control input. Optionally, once the final pre-defined pose 503, 504 is selected, the control unit 303 may initiate the calibration mode. The control input may be received from the user input device for the pre-defined poses, the surgeon console 304, or another input on the robot 301 , 302.

[0100] Referring to Figure 6, the control unit 303 may initially be in the surgical mode 505 or the compliant mode 506. The control unit 303 may come out of the surgical mode 505 or the compliant mode 506 in response to a control input. The control input may be received from the user input device for the pre-defined poses, the surgeon console 304, or another input on the robot 301 , 302. The user may press and hold the button, and the robot arm 402 may move to the pre-defined pose 503. If the button is released once the robot arm 402 reaches the pre-defined pose 503, the robot arm 402 may stay in the pre-defined pose 503. If the button is not released once the robot arm 402 reaches the pre-defined pose 503, the robot arm 402 may continue to move into another pose. The robot arm 402 may or may not move straight after the pre-defined pose 503 is reached. For example, the robot arm 402 may stay in the pre-defined pose 503 for a period of time before continuing to move. The control unit 303 may continue the same process for a plurality of further pre-defined poses 504. The robot arm 402 may cycle through each of the pre-defined poses 504. The number of further predefined poses 504 may be varied depending on how many options are required. Once the final pre-defined pose 504 is selected, the control unit 303 may initiate the surgical mode 505 or the compliant mode 506 in response to a control input. The control unit may be received from the user input device for the pre-defined poses, the surgeon console 304, or another input on the robot 301 , 302.

[0101] The pre-defined poses 503 may be optimised in dependence on the strength of the joints 405. The selected pre-defined pose 503 may be one of a subset of the plurality of pre-defined poses 503, 504 in which the robot arm 402 is arranged such that each of the joints 405 of the robot arm 402 are positioned so as to reduce loading on joints driven by a driver with a lower rated load. The pre-defined poses 503 may be optimised in dependence on the rated load of the drivers of the joints 405. The pre-defined poses 503 may aim to avoid overloading the joints 405 in certain directions.

[0102] Some joints 405 may be weaker or stronger in certain directions. For example, some of the joints 405 may be weaker or stronger due to the design of the drivers, which may be driven by motors. For example, the drivers may comprise a gear such as a worm gear. Figure 8 illustrates the interaction between two gears 801 , 802 of a driver. The teeth 803 on the gears 801 , 802 may be asymmetrical. The teeth 803 on the gear may be angled or curved on one side 804 and straight on the other side 805. Pushing with the straight side 805 may be stronger - this is illustrated by the clockwise arrow in Figure 8. The straight side 805 of a tooth 803 of a first gear 801 contacting the straight side 805 of a tooth 803 of a second gear 802 may provide a stronger engagement. On the other hand pushing with the angled or curved side 804 may be weaker - this is illustrated by the counterclockwise arrow in Figure 8. The angled side 804 of a tooth 803 of a first gear 801 contacting the angled side 804 of a tooth 803 of a second gear 802 may provide a weaker engagement. The weaker engagement may cause slipping. Two angled or curved sides 804 may be more likely to slip when loaded. Two straight sides 805 may be less likely to slip when loaded. Slipping may damage the motor. The likelihood of slipping may dictate the rated load of the driver.

[0103] One or more of the drivers may be asymmetrical rated load drivers. Each asymmetrical rated load driver may have a first rated load in a first direction of rotation of the joint 405 and have a second rated load in a second direction of rotation of the joint 405. The first rated load may be higher than the second rated load. Put another way, the driver may have a higher rated load in one direction (e.g., clockwise) than the opposite direction (e.g., anti-clockwise) or vice versa.

[0104] In a pre-defined pose 503, the robot arm 402 may be arranged such that when the instrument 404 is attached the weight of the instrument 404 causes a torque that acts against the first direction of rotation of a joint 405 that is driven by an asymmetrical rated load driver. For example, if the driver is weaker in the anticlockwise direction, then the pre-defined pose 503 may aim to load the clockwise direction of the driver. The weight of the instrument 404 may be applied at the most distal member 406. The force of the weight of the instrument 404 may be transferred down through the members 406 causing a torque on each of the joints 405. This may be repeated across one or more of the drivers. This may be repeated across all of the drivers. In the predefined pose 503, the robot arm 402 may be arranged such that when the instrument 404 is attached the weight of the instrument 404 causes a torque that acts against the first direction of rotation of all the joints 405 that are driven by an asymmetrical rated load driver.

[0105] In a pre-defined pose 503, the robot arm 402 may be arranged such that a force acting in the instrument 404 engagement direction of the interface causes a torque that acts against the first direction of rotation of a joint 405 that is driven by an asymmetrical rated load driver. For example, if the driver is weaker in the anticlockwise direction, then the pre-defined pose 503 may aim to load the clockwise direction of the driver. The force of the instrument 404 being pushing onto the interface 403 may be applied at the most distal member 406. The force of the weight of the instrument 404 may be transferred down through the members 406 causing a torque on each of the joints 405. This may be repeated across one or more of the drivers. This may be repeated across all of the drivers. In the pre-defined pose 503, the robot arm 402 may be arranged such that a force acting in the instrument 404 engagement direction of the interface causes a torque that acts against the first direction of rotation of all the joints 405 that are driven by an asymmetrical rated load driver. In a particular implementation, the robot arm 402 may comprise a wrist proximal of the interface 403. The wrist may be located at the most distal joint 405c. The wrist may comprise a pitch joint and a yaw joint. The axis of the pitch joint may intersect the axis of the yaw joint. The pitch joint may be as described herein with reference to Figure 4. The yaw joint may be as described herein with reference to Figure 4. The pitch joint may be driven by an asymmetrical rated load driver. The yaw joint may be driven by an asymmetrical rated load driver. The wrist may need to be small as it is located near to the patient where clashes may occur with other robot arms 302 and the patient. As such, the drivers of the wrist may be smaller and have a lower load rated driver.

[0106] The wrist may also carry most of the load from the instrument 404, because the instrument 404 is located near to the wrist. The wrist may carry most of the load from the weight of the instrument. In the pre-defined pose 503, the robot arm 402 may be arranged such that when the instrument 404 is attached the weight of the instrument 404 causes a torque that acts against the first direction of rotation of the pitch joint driven by an asymmetrical rated load driver. Additionally, or alternatively, in the predefined pose 503, the robot arm 402 may be arranged such that when the instrument 404 is attached the weight of the instrument 404 causes a torque that acts against the first direction of rotation of the yaw joint driven by an asymmetrical rated load driver. The wrist may carry most of the load from the engagement of the instrument. In the pre-defined pose 503, the robot arm 402 may be arranged such that a force acting in the instrument 404 engagement direction of the interface causes a torque that acts against the first direction of rotation of the pitch joint driven by an asymmetrical rated load driver. Additionally, or alternatively, in the pre-defined pose 503, the robot arm 402 may be arranged such that a force acting in the instrument 404 engagement direction of the interface causes a torque that acts against the first direction of rotation of the yaw joint driven by an asymmetrical rated load driver.

[0107] The pre-defined poses 503 may be optimised in dependence on the range of motion of the joints 405. The selected pre-defined pose 503 may be one of a subset of the plurality of pre-defined poses 503, 504 in which the robot arm 402 is arranged such that each of the joints 405 of the robot arm 402 are positioned within a threshold range of motion of the total range of motion of the joint 405. The pre-defined poses 503 may aim to avoid pushing the joints 405 to the extremes of their range of motion. For example, pushing each of the joints 405 to their maximum angle. The pre-defined poses 503 may also aim to avoid pushing the robot arm 402 as a whole to the extremes of its range of motion. For example, pushing the robot arm 402 to the end of its travel - such as full extension. The pre-defined pose 503 is ideally arranged such that each of the joints 405 are at the centre of their range of motion. The centre of the range of motion may be defined as 50%. The ends of the range of motion may be defined as 0% and 100%. The joints 405 have different amounts of range of motion. A joint 405 with a range of motion of 180 degrees would have 0% at 0 degree, 50% at 90 degrees, and 100% at 180 degrees. Setting the pre-defined pose 503 with joints 405 at the centre of the range of motion can maximise the positions to which the robot arm 402 can move to from the pre-defined pose 503. This can allow the robot arm 402 to have more potential positions to be used during surgery. Preferably, in the pre-defined pose 503, the robot arm 402 may be arranged such that each of the joints 405 of the robot arm 402 are positioned within 10% to 90% of total range of motion of the joint 405. More preferably, in the pre-defined pose 503, the robot arm 402 may be arranged such that each of the joints 405 of the robot arm 402 are positioned within 40% to 60% of total range of motion of the joint 405. Even more preferably, in the pre-defined pose 503, the robot arm 402 may be arranged such that each of the joints 405 of the robot arm 402 are positioned at about 50% of total range of motion of the joint 405.

[0108] The pre-defined poses 503 may be optimised in dependence on potential clashes. The selected pre-defined pose 503 may be one of a subset of the plurality of pre-defined poses 503, 504 in which the robot arm 402 is arranged such that each of the joints 405 of the robot arm 402 are positioned with a reduced risk of clashes.

[0109] The pre-defined poses 503 may aim to avoid clashes between the robot arm 402 of the robot 301 with the robot arm 402 of another robot 302. The pre-defined poses 503 may aim to avoid clashes between the robot arm 402 of the robot 301 with the robot arm 402 of another robot 302 when the robot arm 402 is on route to the pre-defined pose 503. The route to the pre-defined pose 503 ideally does not overlap with the location of the robot arm 402 of another robot 302. The pre-defined pose 503 is ideally located away from the robot arm 402 of another robot 302. The pre-defined pose 503 may be located outside of a workspace volume surrounding the robot arm 402 of another robot 302. The pre-defined poses 503 may aim to avoid clashes between the robot arm 402 with the robot arm 402 of another robot 302 after the robot arm 402 moves from the pre-defined pose 503. The pre-defined pose 503 is ideally located away from the robot arm 402 of another robot 302 and subsequent movements are in a direction away from the robot arm 402 of another robot 302. Put another way, clashes may occur during the following stages: (i) during movement of the robot arm 402 to the pre-defined pose 503 along the route, (ii) once the robot arm 402 moves into in the pre-defined pose 503, (iii) and during subsequent movements of the robot arm 402 once it has left the pre-defined pose 503. The position of the robot arm 402 preferably does overlap with the position of a robot arm 402 of another robot 302 during all three stages. The robot arm 402 preferably remains outside of the workspace volume of the robot arm 402 of the other robot 302 during all three stages.

[0110] As described herein, the different robots 301 , 302 may be located independently of each other. The control unit 303 may be configured to receive the relative orientations of each of the plurality of robot arms 402. The control unit 303 may be configured to receive the arrangements of each of the plurality of robot arms 402. Based on this information, the control unit 303 may determine whether the robot arms 402 of the different robots 301 , 302 may clash.

[0111] The pre-defined pose 503 may be one of a subset of the plurality of pre-defined poses 503, 504 in which the robot arm 402 is arranged such that each of the joints 405 of the robot arm 402 are positioned such that subsequent movements of the joints 405 within a threshold movement range do not cause a clash between the robot arm 402 and one of the other plurality of robot arms 402. For example, the control unit 303 may be able to determine how far the robot arm 402 can move before a clash occurs with another robot arm 402, this may be the threshold movement range. The threshold movement range may be predetermined. The threshold movement range may be input to the control unit 303 before use of the robot. The threshold movement range may be based on the maximum extension of the robot arm 402. The threshold movement range may be determined by the control unit 303 based on the relative orientations of the robot arms 402, and / or the arrangements of the robot arms 402. The control unit 303 may determine the pre-defined pose 503 so that the robot arm 402 avoids a clash with another robot arm 402 within the threshold movement range. The same may apply to other objects in the operating room. The location of the bed and other surgical equipment may be input into the control unit 303. The control unit 303 may also control the robot arm 402 to avoid clashes with other surrounding objects due to subsequent movements of the robot arm 402.

[0112] The pre-defined pose 503 may be one of a subset of the plurality of pre-defined poses 503, 504 in which the robot arm 402 is arranged in a pose that does not cause a clash with another robot arm 402. The pre-defined pose 503 may not cause a clash between the robot arm and another robot arm 402. For example, the control unit 303 may be able to determine whether the pre-defined pose 503 overlaps with the position of another robot arm 402. The same may apply to other objects in the operating room. The location of the bed and other surgical equipment may be input into the control unit 303. The control unit 303 may also control the robot arm 402 to avoid clashes with other surrounding objects due to positioning the robot arm 402 in the pre-defined pose 503.

[0113] The pre-defined pose 503 may be one of a subset of the plurality of pre-defined poses 503, 504 in which the route to the pre-defined pose 503 does not cause a clash with another robot arm 402. The control unit 303 may control the drivers to move the robot arm 402 so that the robot arm 402 is arranged in the pre-defined pose 503 along a route which does not cause a clash between the robot arm 402 and one of the other plurality of robot arms 402. For example, the control unit 303 may be able to determine whether the route to the pre-defined pose 503 overlaps with the position of another robot arm 402. The same may apply to other objects in the operating room. The location of the bed and other surgical equipment may be input into the control unit 303. The control unit 303 may also control the robot arm 402 to avoid clashes with other surrounding objects due to moving the robot arm 402 along the route to the pre-defined pose 503.

[0114] The pre-defined pose 503 may be one of a subset of the plurality of pre-defined poses 503, 504 that are optimised in dependence on data from the surgical robotic system 300. The pre-defined pose 503 may be optimised for a particular implementation. The data from the surgical robotic system 300 may characterise the particular implementation in a form in which the control unit 303 can set the pre-defined pose 503. The data from the surgical robotic system 300 may include the selected predefined pose 503. The data from the surgical robotic system 300 may include a plurality of pre-defined poses 503, one of which is to be selected.

[0115] The control unit 303 may receive the data from the surgical robotic system 300. The data from the surgical robotic system 300 may be input into the control unit 303. The data from the surgical robotic system 300 may be input into the mobile device described herein. For example, the patient characteristics may be input into the mobile device. The mobile device may retrieve the data from the surgical robotic system 300. The mobile device may retrieve the data from the surgical robotic system 300 from a storage means. As an example, the surgeon, or other member of medical staff, may input data from the surgical robotic system 300 into the control unit 303, such as through the mobile device.

[0116] The pre-defined pose 503 may be selected by the control unit 303 based on data from the surgical robotic system 300. If the data from the surgical robotic system 300 already selects a pre-defined pose 503, then the control unit 303 may select that predefined pose 503. If the data from the surgical robotic system 300 includes a plurality of pre-defined poses 503, the control unit 303 may select a pre-defined pose 503. The data from the surgical robotic system 300 may not include a pre-defined pose 503 at all.

[0117] The data from the surgical robotic system 300 may comprise the position of the robot arm 402 relative to the other robot arms 402 of the plurality of robot arms 402. The control unit 303 may then select the pre-defined pose 503 based on the avoidance of clashes between the robot arms 402. The data from the surgical robotic system 300 may comprise the position of the robot arm 402 relative to the position of a surrounding object, such as an operating bed. The control unit 303 may then select the pre-defined pose 503 based on the avoidance of clashes between robot arm 402 and the bed. The control unit 303 may then select the pre-defined pose 503, additionally or alternatively, based on positioning the robot arm 402 in a position relative to the surrounding object, such as the operating bed. The position of the robot arm 402 relative to the bed may be optimised for carrying out surgery. The data from the surgical robotic system 300 may comprise the characteristics of a patient. The control unit 303 may then select the pre-defined pose 503 based on positioning the robot arm 402 in a position relative to patient. The position of the robot arm 402 relative to the bed may be optimised for certain patients. The data from the surgical robotic system 300 may comprise the characteristics of a surgical procedure. The control unit 303 may then select the predefined pose 503 based on positioning the robot arm 402 in a position relative to patient. The position of the robot arm 402 relative to the bed may be optimised for certain procedures.

[0118] The characteristics of the patient may comprise the height of the patient. A patient with a larger height may require the robot arms 402 to be located in a different position to a patient with a smaller height. A patient with a larger height may require the robot arms 402 to be located on the sides of the operating bed due to the distance from the head / feet to the operating area. The same requirement may not be required for a patient with a smaller height. The characteristics of the patient may comprise the BMI of the patient. A patient with higher BMI may require the robot arms 402 to be located in a different position to a patient with a lower BMI. A patient with a higher BMI may require the robot arms 402 to be located above the operating bed to give an angle into the operating area. The same requirement may not be required for a patient with a lower BMI. The characteristics of the patient may comprise the gender of the patient. The gender of the patient may change the procedures being undertaken, which may require the robot arms 402 to be located in different positions. The characteristics of the patient may comprise the orientation of the patient on the bed. The orientation of the patient may be dependent on the procedures being undertaken. Some procedures may require access to the front of the patient, and some may require access to the side or back of the patient. This may change the height and / or angle required for the instrument 404.

[0119] 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.

Claims

AMENDED CLAIMS received by the International Bureau on 16 January 2026 (16.01.2026)Claims1 . A surgical robotic system comprising: a plurality of robots, the robots being physically independent to each other, each robot having a base, and an arm extending from the base to an interface for engaging an instrument, the arm comprising a plurality of joints whereby the arrangement of the arm can be altered, for each joint the robot comprising a driver configured to drive the joint to move; and a control unit configured to receive control inputs and control the drivers in dependence on those control inputs, the control unit being configured to: receive a selection control input; receive data from the surgical system; select a pre-defined pose of a plurality of pre-defined poses for one of the robot arms in dependence on the selection control input and data from the surgical robotic system; and control the drivers to move the robot arm from an initial pose so that the robot arm is arranged in the pre-defined pose; wherein the pre-defined pose is one of a subset of the plurality of pre-defined poses in which the robot arm is arranged such that each of the joints of the robot arm is positioned within a threshold range of motion of the total range of motion of the joint.

2. A surgical robotic system according to claim 1 , wherein one or more of the drivers are asymmetrical rated load drivers, each asymmetrical rated load driver having a first rated load in a first direction of rotation of the joint and having a second rated load in a second direction of rotation of the joint, the first rated load being higher than the second rated load.

3. A surgical robotic system accordingto claim 2, wherein, in the pre-defined pose, the robot arm is arranged such that when the instrument is attached the weight of the instrument causes a torque that acts against the first direction of rotation of a joint that is driven by an asymmetrical rated load driver.

4. A surgical robotic system according to claim 2 or 3, wherein, in the pre-defined pose, the robot arm is arranged such that a force acting in the instrument engagementdirection of the interface causes a torque that acts against the first direction of rotation of a joint that is driven by an asymmetrical rated load driver.

5. A surgical robotic system according to any preceding claim, wherein the robot arm comprises a wrist proximal of the interface, the wrist comprising a pitch joint and a yaw joint, the axis of the pitch joint intersecting the axis of the yaw joint.

6. A surgical robotic system according to claim 5, wherein the pitch joint is driven by an asymmetrical rated load driver and / or the yaw joint is driven by an asymmetrical rated load driver.

7. A surgical robotic system according to claim 6, in the pre-defined pose, the robot arm is arranged such that when the instrument is attached the weight of the instrument causes a torque that acts against the first direction of rotation of the pitch joint driven by an asymmetrical rated load driver and / or acts against the first direction of rotation of the yaw joint driven by an asymmetrical rated load driver.

8. A surgical robotic system according to claim 6 or 7, wherein, in the pre-defined pose, the robot arm is arranged such that a force acting in the instrument engagement direction of the interface causes a torque that acts against the first direction of rotation of the pitch joint driven by an asymmetrical rated load driver and / or acts against the first direction of rotation of the yaw joint driven by an asymmetrical rated load driver.

9. A surgical robotic system according to any preceding claim, wherein, in the predefined pose, the robot arm is arranged such that each of the joints of the robot arm is positioned within 10% to 90% of total range of motion of the joint.

10. A surgical robotic system according to any preceding claim, wherein, in the predefined pose, the robot arm is arranged such that each of the joints of the robot arm are positioned within 40% to 60% of total range of motion of the joint.

11. A surgical robotic system according to any preceding claim, wherein the control unit is configured to receive the relative orientations of each of the plurality of robot arms,and / or wherein the control unit is configured to receive the arrangements of each of the plurality of robot arms.

12. A surgical robotic system according to claim 11 , wherein the control unit is configured to control the drivers to move the robot arm so that the robot arm is arranged in the pre-defined pose along a route which does not cause a clash between the robot arm and one of the other plurality of robot arms.

13. A surgical robotic system according to claim 11 or 12, wherein the pre-defined pose is one of a subset of the plurality of pre-defined poses in which the robot arm is arranged such that each of the joints of the robot arm are positioned such that subsequent movements of the joints within a threshold movement range do not cause a clash between the robot arm and one of the other plurality of robot arms.

14. A surgical robotic system according to any of claims 11 to 13, wherein the predefined pose is one of a subset of the plurality of pre-defined poses in which the robot arm is arranged such that each of the joints of the robot arm are positioned such that, in the pre-defined pose, the robot arm does not cause a clash between the robot arm and one of the other plurality of robot arms.

15. A surgical robotic system according to any preceding claim, wherein the predefined pose is one of a subset of the plurality of pre-defined poses that are optimised in dependence on data from the surgical robotic system.

16. A surgical robotic system according to claim 15, wherein data from the surgical robotic system comprises one or more of: the position of the robot arm relative to the other robot arms of the plurality of robot arms; the position robot arm relative to the position of an operating bed; the characteristics of a patient; and the characteristics of a surgical procedure.17 A surgical robotic system according to claim 16, wherein the characteristics of the patient comprise one or more of:the height of the patient; the BMI of the patient; the gender of the patient; and the orientation of the patient on the operating bed.

18. A surgical robotic system according to any preceding claim, wherein the control unit is configured to operate in: a surgical mode in which the control unit is configured to control the movement of the robot arm in dependence on inputs from a surgical console; and a compliant mode in which the control unit is configured to control the movement of the robot arm in dependence on inputs from torque sensors measuring torque on the joints due to external forces on the robot arm.

19. A surgical robotic system according to claim 18, wherein in the surgical mode the instrument is engaged with the interface.

20. A surgical robotic system according to any preceding claim, wherein the initial pose is a sleep pose in which the arrangement of the robot arm minimises the external volume of the robot arm.21 . A surgical robotic system according to claim 20, wherein the pre-defined pose is a wake pose in which the arrangement of the robot arm increases the external volume of the robot arm compared to the sleep pose.

22. A surgical robotic system according to any of claims 18 to 20, wherein the predefined pose is the start pose of the surgical mode and / or the pre-defined pose is the start pose of the compliant mode.

23. A surgical robotic system according to claim 18 or 19, wherein the initial pose is a final pose of the surgical mode and / or the initial pose is a final pose of the compliant mode.

24. A surgical robotic system according to any preceding claim, wherein the predefined pose comprises one of: a drape pose in which the arrangement of the robot arm forms a substantially straight line; a horseshoe pose in which the arrangement of the robot arm forms a horseshoe shape; a C-shape pose in which the arrangement of the robot arm forms a C-shape; and a Z-shape pose in which the arrangement of the robot arm forms a Z-shape.

25. A surgical robotic system according to any preceding claim, wherein the control unit is configured to: receive a further selection control input; select a further pre-defined pose of a plurality of pre-defined poses for one of the robot arms in dependence on the further selection control input; and control the drivers to move the robot arm from the pre-defined pose so that the robot arm is arranged in the further pre-defined pose.

26. A surgical robotic system according to any preceding claim, wherein the control unit is configured to receive the selection control input from a user input device, and optionally wherein the user input device is located on one or more of: the base of the robot; the arm of the robot; a surgeon console; and a mobile device connected to the surgical robotic system.

27. A surgical robotic system according to claim 26, wherein the user input device comprises a button.

28. A surgical robotic system accordingto claim 26 or 27 wherein, in response to the user input device being continuously activated, the control unit is configured to control the drivers to move the robot arm from the initial pose so that the robot arm is arranged in the pre-defined pose, and optionally wherein the control unit is configured to stopcontrollingthe drivers to move the robot arm if the user input device is deactivated before the robot arm is arranged in the pre-defined pose.

29. A surgical robotic system according to claim 28 when dependent on claim 25, wherein, in response to the user input device being continuously activated after the robot arm is in the pre-defined pose, the control unit is configured to control the drivers to move the robot arm from the pre-defined pose so that the robot arm is arranged in the further pre-defined pose, and optionally wherein the control unit is configured to stop controlling the drivers to move the robot arm if the user input device is deactivated before the robot arm is arranged in the further pre-defined pose.

30. A surgical robotic system according to any preceding claim, wherein the control unit is configured to output a user output once the robot arm is in the pre-defined pose.

31. A surgical robotic system according to claim 30, wherein the user output comprises one or more of: an audible output; a visible output; and a physical output.

32. A surgical robotic system according to any of claims 18 to 31 , wherein, in the surgical mode, the control unit is configured such that all the drivers are operable to move all the joints of the robot arm.

33. A method for controlling a surgical robotic system, the surgical robotic system comprising: a plurality of robots, the robots being physically independent to each other, each robot having a base, and an arm extending from the base to an interface for engaging an instrument, the arm comprising a plurality of joints whereby the arrangement of the arm can be altered, for each joint the robot comprising a driver configured to drive the joint to move; and a control unit configured to receive control inputs and control the drivers in dependence on those control inputs;the method comprising steps of, the control unit: receiving a selection control input; selecting a pre-defined pose of a plurality of pre-defined poses for one of the robot arms in dependence on the selection control input; and controlling the drivers to move the robot arm from an initial pose so that the robot arm is arranged in the pre-defined pose; wherein the pre-defined pose is one of a subset of the plurality of pre-defined poses in which the robot arm is arranged such that each of the joints of the robot arm is positioned within a threshold range of motion of the total range of motion of the joint.

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