Robot tool retraction

Abstract

A robot comprising: a base; a flexible arm extending from the base and having: a plurality of joints whereby the configuration of the arm can be altered, a plurality of drivers arranged to drive the joints to move, and an attachment structure for attaching a tool to the arm; and a control unit configured to control the drivers and to receive inputs from sensors, and operable in a mode in which, whilst a tool is attached to the attachment structure and captive in a port, it: (i) controls the drivers to permit the arm to be reconfigured by the action of an external force applied to the arm so as to cause the tool to be retracted from the port along a longitudinal axis of the tool; and (ii) on receiving sensor input indicating that the arm has been reconfigured so as to cause the tool to be retracted from the port along a longitudinal axis of the tool, controls the drivers to reconfigure the arm so as to agitate the tool transverse to the longitudinal axis of the tool.

1 - 19 . (canceled) 
     
     
         20 . A surgical robot comprising a flexible robot arm extending from a 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 for attaching a tool to the arm, and a control unit configured to control the drivers, the control unit being configured to:
 operate in a compliant mode in which the control unit controls the drivers such that the arm maintains a position in which it is placed as a result of a force applied directly to the arm;   operate in a compliant calibration mode in which the control unit is configured to determine an estimated port location in which the tool attached to the attachment structure is located as an operator moves a distal end of the arm whilst the tool is located in a port; and   operate in a driven mode in which the configuration of the arm is driven in dependence on inputs received from a controller and the estimated port location.   
     
     
         21 . The surgical robot as claimed in  claim 20 , wherein the control unit is configured to:
 operate in the compliant mode;   subsequently, operate in the compliant calibration mode; and   subsequently, operate in the driven mode.   
     
     
         22 . The surgical robot as claimed in  claim 20 , wherein, in the compliant mode, the control unit is configured to control the drivers to permit the arm to be reconfigured through action of an external force applied to the arm so as to permit the operator to insert the tool into the port. 
     
     
         23 . The surgical robot as claimed in  claim 20 , wherein, the configuration is a first configuration and in the driven mode, the control unit is configured to:
 receive a demand signal from the controller indicating a desired location of a part of the tool;   calculate a second configuration of the arm in which the part of the tool will be at the desired location and the tool intersects the estimated port location; and   control the drivers so the arm adopts the calculated second configuration.   
     
     
         24 . The surgical robot as claimed in  claim 20 , wherein the controller is remote from the surgical robot. 
     
     
         25 . The surgical robot as claimed in  claim 20 , wherein the controller is a three-dimensional controller. 
     
     
         26 . The surgical robot as claimed in  claim 20 , wherein the tool is a surgical tool. 
     
     
         27 . The surgical robot as claimed in  claim 20 , wherein, in the compliant calibration mode, the control unit is configured to control the drivers to permit the arm to be reconfigured through action of an external force applied to the arm so as to permit the operator to move the distal end of the arm in directions transverse to a longitudinal axis of a tool shaft of the tool such that the port exerts a lateral force on the tool shaft where it passes through the port. 
     
     
         28 . The surgical robot as claimed in  claim 27 , wherein the tool shaft is straight. 
     
     
         29 . The surgical robot as claimed in  claim 20 , wherein the surgical robot further comprises a plurality of position sensors, and the control unit is further configured to, in the compliant calibration mode:
 receive inputs from the plurality of position sensors indicative of a current configuration of the arm as the operator moves the distal end of the arm;   calculate a plurality of data pairs in dependence on the received inputs, each of the plurality of data pairs comprising (a) a calculated position of the distal end of the surgical robot relative to the base and (b) a vector of a tool shaft relative to the distal end of the robot; and   estimate the location of the port relative to the base as the location where tool shaft vectors of the plurality of data pairs converge.   
     
     
         30 . The surgical robot as claimed in  claim 20 , wherein the estimated port location is a natural rotation center of the port. 
     
     
         31 . The surgical robot as claimed in  claim 20 , wherein the port is sited in a patient. 
     
     
         32 . The surgical robot as claimed in  claim 20 , wherein the control unit is configured to store the estimated port location in a memory prior to operating in the driven mode. 
     
     
         33 . The surgical robot as claimed in  claim 20 , wherein the control unit comprises a processor and a memory storing non-transiently a set of instructions executable by the processor for implementing the compliant mode, the compliant calibration mode and the driven mode. 
     
     
         34 . The surgical robot as claimed in  claim 20 , wherein the control unit is configured to initiate operation in the compliant mode, the compliant calibration mode or the driven mode in response to receiving user input via a control panel or a button on the arm. 
     
     
         35 . The surgical robot as claimed in  claim 20 , wherein the control unit is configured to, in the compliant mode and the compliant calibration mode, control the drivers so as to resist an action of gravity and thereby cause the arm to maintain a pushed configuration imposed by an external force independent of the action of gravity. 
     
     
         36 . The surgical robot as claimed in  claim 20 , wherein the surgical robot further comprises a plurality of force sensors for sensing applied torque about the joints, and the control unit is further configured to, in the compliant mode and compliant calibration mode, control the drivers in dependence on an output of the plurality of force sensors. 
     
     
         37 . The surgical robot as claimed in  claim 20 , wherein the control unit is further configured to operate in a retraction mode in which the control unit controls the drivers to reconfigure the arm so as to cause the tool to be retracted from the port along a longitudinal axis of the tool. 
     
     
         38 . The surgical robot as claimed in  claim 35 , wherein the control unit is configured to operate in an instrument retraction mode subsequent to operating in the compliant calibration mode. 
     
     
         39 . The surgical robot as claimed in  claim 38 , wherein, in the instrument retraction mode, the control unit is configured to control the drivers to permit the arm to be reconfigured through action of the external force applied to the arm so as to cause the tool to be retracted from the port along a longitudinal axis of the tool.