Robot tool retraction

1. A robot comprising:

a base;

a flexible arm extending from the base and having:

a plurality of joints whereby a configuration of the arm can be altered,

a plurality of drivers arranged to drive the joints to move, and

an attachment structure configured to attach a tool, which is separate and distinct from the arm, to the arm; and

a control unit, comprising a processor and a memory, configured to control the drivers in the arm and operable in a retraction mode in which, whilst the tool is attached to the attachment structure and captive in a port, the control unit:

(i) controls the drivers in the arm to reconfigure the arm so as to cause the tool to be retracted from the port along a longitudinal axis of the tool; and

(ii) on retracting the tool from the port along the longitudinal axis of the tool, controls the drivers in the arm to reconfigure the arm so as to agitate the tool transverse to the longitudinal axis of the tool.

2. The robot as claimed in claim 1 , wherein the control unit is configured to control the drivers to agitate the tool by causing the attachment structure to rotate about the longitudinal axis of the tool.

3. The robot as claimed in claim 1 , wherein the control unit is configured to control the drivers to agitate the tool by causing an angular attitude of the attachment structure relative to the base to be varied.

4. The robot as claimed in claim 1 , wherein the control unit is configured to control the drivers to agitate the tool transverse to the longitudinal axis of the tool as a function of retracting the tool along the longitudinal axis of the tool.

5. The robot as claimed in claim 1 , further comprising the tool attached to the attachment structure, the tool being a surgical tool.

6. The robot as claimed in claim 1 , wherein the control unit is configured to:

receive inputs from sensors, and

on receiving sensor input indicating that the arm has been reconfigured so as to cause the tool to be retracted from the port along the longitudinal axis of the tool, controlling the drivers to reconfigure the arm so as to agitate the tool transverse to the longitudinal axis of the tool.

7. The robot as claimed in claim 1 , wherein the arm comprises a plurality of sensors configured to sense forces applied about the joints, and the control unit is configured to, in the retraction mode, control the drivers in dependence on outputs of the sensors.

8. The robot as claimed in claim 5 , wherein the tool comprises a plurality of sensors configured to sense forces applied to the tool, and the control unit is configured to, in the retraction mode, control the drivers in dependence on outputs of the sensors.

9. The robot as claimed in claim 1 , wherein the control unit is configured to control the drivers to permit the arm to be reconfigured by action of an external force applied to the arm so as to cause the tool to be retracted from the port along the longitudinal axis of the tool.

10. The robot as claimed in claim 1 , wherein in the retraction mode, the control unit is configured to control the drivers to prevent the arm from being reconfigured by action of an external force applied to the arm so as to cause the tool to move transverse to the longitudinal axis of the tool.

11. The robot as claimed in claim 1 , wherein in the retraction mode, the control unit is configured to control the drivers to prevent the arm from being reconfigured by action of an external force applied to the arm so as to cause the tool to be further inserted into the port along the longitudinal axis of the tool.

12. The robot as claimed in claim 1 , wherein the control unit is configured to, in the retraction mode, control the drivers so as to resist action of gravity and thereby cause the arm to maintain a configuration imposed by an external force independently of the action of gravity.

13. The robot as claimed in claim 1 , wherein the control unit is configured to, in the retraction mode, control the drivers so as to present a limited resistance to reconfiguration under an external force independently of action of gravity.

14. The robot as claimed in claim 1 , wherein the control unit is configured to initiate operation in the retraction mode in response to receiving input from an operator via at least one of a control panel, a 3D controller, or user input on the arm.

15. The robot as claimed in claim 1 , wherein the control unit is configured to control the drivers to reconfigure the arm so as to cause the tool to be retracted from the port along the longitudinal axis of the tool in response to receiving a control input from an operator via at least one of a control panel, a 3D controller, or user input on the arm.

16. The robot as claimed in claim 1 , wherein the control unit is operable in a driven mode in which, when the tool is attached to the attachment structure, the control unit receives a demand signal indicating a desired location of a part of the tool, calculates a configuration of the arm in which the part of the tool will be at the desired location and the tool intersects the location of the port, and controls the drivers so the arm adopts the calculated configuration.

17. The robot as claimed in claim 1 , wherein the memory is configured to store non-transiently a set of instructions executable by the processor to implement the mode.

18. The robot as claimed in claim 1 , wherein the robot is a surgical robot.

19. A method of controlling a robot, the robot comprising a base, a flexible arm extending from the base and having a plurality of joints whereby a configuration of the arm can be altered, a plurality of drivers arranged to drive the joints to move, and an attachment structure configured to attach a tool, which is separate and distinct from the arm, to the arm, the method comprising, whilst the tool is attached to the attachment structure and captive in a port:

controlling the drivers in the arm so as to reconfigure the arm so as to cause the tool to be retracted from the port along a longitudinal axis of the tool; and

on retracting the tool from the port along the longitudinal axis of the tool, controlling the drivers in the arm to reconfigure the arm so as to agitate the tool transverse to the longitudinal axis of the tool.

20. A robot comprising:

a base;

an arm coupled to and extending from the base, the arm comprising

an attachment structure to attach a tool, which is separate and distinct from the arm, to the arm;

a plurality of joints; and

a plurality of drivers coupled to the plurality of joints to drive movement of the plurality of joints; and

a control unit, comprising a processor and a memory, coupled to the plurality of drivers in the arm and configured to control the plurality of drivers in the arm to agitate the tool transverse to a longitudinal axis of the tool while retracting the tool from a port.