Alignment of master and slave in a minimally invasive surgical apparatus

• US 6,364,888 B1
• Filed: 04/07/1999
• Issued: 04/02/2002
• Est. Priority Date: 09/09/1996
• Status: Expired due to Term

• Current Assignee: Intuitive Surgical Operations, Inc. (Intuitive Surgical Holdings, LLC)
• Original Assignee: Intuitive Surgical Incorporated (Intuitive Surgical Holdings, LLC)
• Inventors: Guthart, Gary S., Niemeyer, Gunter D., Nowlin, William C.
• Primary Examiner(s): Smith, Jeffrey A.
• Assistant Examiner(s): Priddy, Michael B.
• Application Number:
  US09/287,858
• Time in Patent Office: 1,091 Days
• Field of Search: 606/130, 318/568.11, 414/1, 348/65
• US Class Current: 606/130
• CPC Class Codes: A61B 1/00149 using articulated arms
• CPC Class Codes: A61B 17/00234 for minimally invasive surgery A61B17/0218, A61B17/0469, A61B17/12013, A61B17/1285, A61B17/29, A61B17/320016 take precedence
• CPC Class Codes: A61B 2018/00982 combined with or comprising means for visual or photographic inspections inside the body, e.g. endoscopes
• CPC Class Codes: A61B 2034/102 Modelling of surgical devices, implants or prosthesis
• CPC Class Codes: A61B 2034/305 Details of wrist mechanisms at distal ends of robotic arms
• CPC Class Codes: A61B 2090/506 using a parallelogram linkage, e.g. panthograph
• CPC Class Codes: A61B 34/30 Surgical robots
• CPC Class Codes: A61B 34/35 for telesurgery
• CPC Class Codes: A61B 34/37 Master-slave robots A61B34/35 takes precedence
• CPC Class Codes: A61B 34/70 Manipulators specially adapted for use in surgery
• CPC Class Codes: A61B 90/36 Image-producing devices or illumination devices not otherwise provided for
• CPC Class Codes: B25J 19/023 including video camera means
• CPC Class Codes: B25J 3/04 involving servo mechanisms servo-actuated heads B25J15/02
• CPC Class Codes: B25J 9/1689 Teleoperation
• CPC Class Codes: B25J 9/1692 Calibration of manipulator
• CPC Class Codes: G05B 19/401 characterised by control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes G05B19/19 takes precedence
• CPC Class Codes: G05B 2219/39014 Match virtual world with real world
• CPC Class Codes: G05B 2219/39057 Hand eye calibration, eye, camera on hand, end effector
• CPC Class Codes: G05B 2219/39062 Calculate, jacobian matrix estimator
• CPC Class Codes: G05B 2219/39253 Virtual arm, has end effector on any joint of real manipulator
• CPC Class Codes: G05B 2219/39387 : Reflex control, follow movement, track face, work, hand, visual servoing
• CPC Class Codes: G05B 2219/39389 : Laparoscopic surgery, camera on center of operated part, view around, scale
• CPC Class Codes: G05B 2219/39391 : Visual servoing, track end effector with camera image feedback
• CPC Class Codes: G05B 2219/39394 : Compensate hand position with camera detected deviation, new end effector attitude
• CPC Class Codes: G05B 2219/39437 : Joystick with additional handle for wrist and gripper control
• CPC Class Codes: G05B 2219/39439 : Joystick, handle, lever controls manipulator directly, manually by operator
• CPC Class Codes: G05B 2219/39483 : Control angle of rotation
• CPC Class Codes: G05B 2219/40144 : Force sensation feedback from slave
• CPC Class Codes: G05B 2219/40354 : Singularity detection
• CPC Class Codes: G05B 2219/40552 : Joint limit
• CPC Class Codes: G05B 2219/41441 : Position reference ffw for compensation speed reference and speed error
• CPC Class Codes: G05B 2219/45118 : Endoscopic, laparoscopic manipulator
• CPC Class Codes: H04N 13/239 : using two 2D image sensors having a relative position equal to or related to the interocular distance H04N13/243 takes precedence
• CPC Class Codes: H04N 13/246 : Calibration of cameras
• CPC Class Codes: H04N 13/327 : Calibration thereof
• CPC Class Codes: H04N 23/555 : for picking-up images in sites, inaccessible due to their dimensions or hazardous conditions, e.g. endoscopes or borescopes

Abstract

This invention relates to establishing alignment or a desired orientational relationship between a master and a slave of a telerobotic system. The invention can advantageously be used in a surgical apparatus. A method of establishing a desired orientational relationship between a hand-held part of a master control and an end effector of an associated slave as viewed in an image displayed on a viewer is provided. The method includes causing the end effector to remain stationary, determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with the viewer and determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer, at which orientation the desired orientational relationship between the hand-held part of the master control and the end effector would be established. The method further includes causing the hand-held part of the master control to be moved into the desired corresponding orientation. The invention extends to a control system arranged to cause the desired orientational relationship between the hand-held part of the master control and the end effector of the associated slave, as viewed in the displayed imaged on the viewer, to be established when operative control between the master control and the slave has been interrupted.

Claims

1. A method of establishing a desired orientational relationship between a hand-held part of a master control and an end effector of an associated slave as viewed in an image displayed on a viewer, the method including

causing the end effector to remain stationary;

determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with the viewer;

determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer at which the desired orientational relationship would be established; and

moving the hand-held part of the master control into the desired corresponding orientation.

2. A method as claimed in claim 1, which further includes

determining a current position of the end effector relative to the viewing end of the image capturing device operatively associated with the viewer; and

determining a desired corresponding position of the hand-held part of the master control relative to the viewer at which position a desired positional relationship between the hand-held part of the master control and the end effector would be established; and

moving the hand-held part of the master control into the desired corresponding position.

3. A method as claimed in claim 2, in which moving the hand-held part of the master control into the desired corresponding position includes manually moving the hand-held part.

4. A method as claimed in claim 1, in which moving the hand-held part of the master control into the desired corresponding orientation includes supplying electrical current to electrical motors associated with the hand-held part thereby to cause the hand-held part to be moved into the desired orientation.

5. A method as claimed in claim 1, in which moving the hand-held part of the master control into the desired corresponding orientation includes manually moving the hand-held part.

6. A method of establishing a desired orientational relationship between a hand-held part of a master control and an end effector of an associated slave as viewed in an image displayed on a viewer, the method including

causing the end effector to remain stationary;

determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with the viewer, by computing the orientation relative to a reference coordinate frame positioned at the viewing end of the image capturing device;

determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer at which the desired orientational relationship would be established; and

moving the hand-held part of the master control into the desired corresponding orientation.

7. A method as claimed in claim 6, which further includes defining a coordinate frame on the end effector, the orientation of the end effector then being defined by the orientation of the coordinate frame on the end effector relative to the reference coordinate frame.

8. A method as claimed in claim 6, in which determining the desired corresponding orientation of the hand-held part of the master control relative to the viewer includes computing an orientation of the hand-held part relative to a reference coordinate frame generally at the viewer.

9. A method as claimed in claim 8, in which computing the orientation of the hand-held part relative to the reference coordinate frame generally at the viewer includes defining a coordinate frame on the hand-held part, the orientation of the hand-held part then being defined by the orientation of the coordinate frame on the hand-held part relative to the reference coordinate frame at the viewer.

10. A method as claimed in claim 8, in which determining the desired corresponding orientation of the hand-held part includes determining an orientation of the hand-held part relative to the reference coordinate frame generally at the viewer which is the same as the orientation of the end effector relative to the reference coordinate frame at the image capturing device.

11. A method as claimed in claim 8, in which determining the desired corresponding orientation of the hand-held part includes determining an orientation of the hand-held part relative to the reference coordinate frame generally at the viewer which is offset relative to the orientation of the end effector relative to the reference coordinate frame at the image capturing device.

12. A method of establishing a desired orientational relationship between a hand-held part of a master control and an end effector of an associated slave as viewed in an image displayed on a viewer, the method including

causing the end effector to remain stationary;

determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with the viewer;

determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer at which the desired orientational relationship would be established, the master control having a plurality of configurations which yield the desired corresponding orientation;

computing a preferred configuration of the master control at which the hand-held part is at the desired corresponding orientation; and

moving the hand-held part of the master control into the desired corresponding orientation.

13. A method as claimed in claim 12, in which computing the preferred configuration includes examining a plurality of solutions corresponding to at least one segment of solutions.

14. A method as claimed in claim 13, in which examining the plurality of solutions of the segment includes selecting an arbitrary solution and then following an iterative procedure to compute the preferred solution.

15. A method as claimed in claim 14, in which following an iterative procedure to determine the preferred solution includes using a cost function.

16. A method as claimed in claim 15, in which the preferred solution relates to the solution having a lowest cost function value.

17. A method of establishing a desired orientational relationship between a hand-held part of a master control and an end effector of an associated slave as viewed in an image displayed on a viewer, the method including

causing the end effector to remain stationary;

determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with the viewer;

determining a current position of the end effector relative to the viewing end of the image capturing device operatively associated with the viewer by computing the position relative to a reference coordinate frame positioned at the viewing end of the image capturing device;

determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer at which the desired orientational relationship would be established;

determining a desired corresponding position of the hand-held part of the master control relative to the viewer at which position a desired positional relationship between the hand-held part of the master control and the end effector would be established;

moving the hand-held part of the master control into the desired corresponding orientation; and

moving the hand-held part of the master control into the desired corresponding position.

18. A method as claimed in claim 17, in which computing the position of the end effector relative to the reference coordinate frame at the viewing end of the image capturing device includes defining a coordinate frame on the end effector, the position of the end effector then being defined by the position of the coordinate frame on the end effector relative to the reference coordinate frame.

19. A method as claimed in claim 17, in which determining the desired corresponding position of the hand-held part of the master control relative to the viewer includes computing a position of the hand-held part relative to a reference coordinate frame generally at the viewer.

20. A method as claimed in claim 19, in which computing the position of the hand-held part relative to the reference coordinate frame generally at the viewer includes defining a coordinate frame on the hand-held part, the position of the hand-held part then being defined by the position of the coordinate frame on the hand-held part relative to the reference coordinate frame at the viewer.

21. A method as claimed in claim 19, in which determining the desired corresponding position of the hand-held part includes determining a position of the hand-held part relative to the reference coordinate frame generally at the viewer which is the same as the position of the end effector relative to the reference coordinate frame at the image capturing device.

22. A method as claimed in claim 19, in which determining the desired corresponding position of the hand-held part includes determining a position of the hand-held part relative to the reference coordinate frame generally at the viewer which is offset relative to the position of the end effector relative to the reference coordinate frame at the image capturing device.

23. A method of establishing a desired orientational relationship between a hand-held part of a master control and an end effector of an associated slave as viewed in an image displayed on a viewer, the method including

causing the end effector to remain stationary;

determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with the viewer;

determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer at which the desired orientational relationship would be established;

moving the hand-held part of the master control into the desired corresponding orientation, which includes manually moving the hand-held part; and

causing the hand-held part to be locked in position when its orientation is moved into an orientation in register with the desired corresponding orientation.

24. A method of establishing a desired orientational relationship between a hand-held part of a master control and an end effector of an associated slave as viewed in an image displayed on a viewer, the method including

causing the end effector to remain stationary;

determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with the viewer;

determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer at which the desired orientational relationship would be established;

moving the hand-held part of the master control into the desired corresponding orientation, which includes manually moving the hand-held part; and

providing a signal to an operator manually moving the hand-held part when the hand-held part is moved into an orientation in register with the desired corresponding orientation.

25. A method of establishing a desired orientational relationship between a hand-held part of a master control and an end effector of an associated slave as viewed in an image displayed on a viewer, the method including

causing the end effector to remain stationary;

determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with the viewer;

determining a current position of the end effector relative to the viewing end of the image capturing device operatively associated with the viewer;

determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer at which the desired orientational relationship would be established;

determining a desired corresponding position of the hand-held part of the master control relative to the viewer at which position a desired positional relationship between the hand-held part of the master control and the end effector would be established;

moving the hand-held part of the master control into the desired corresponding orientation; and

moving the hand-held part of the master control into the desired corresponding position by supplying electrical current to electrical motors associated with the hand-held part thereby to cause the hand-held part to be moved into the desired position.

26. A method of establishing a desired orientational relationship between a hand-held part of a master control and an end effector of an associated slave as viewed in an image displayed on a viewer, the method including

causing the end effector to remain stationary;

determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with the viewer;

determining a current position of the end effector relative to the viewing end of the image capturing device operatively associated with the viewer;

determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer at which the desired orientational relationship would be established;

determining a desired corresponding position of the hand-held part of the master control relative to the viewer at which position a desired positional relationship between the hand-held part of the master control and the end effector would be established;

moving the hand-held part of the master control into the desired corresponding orientation; and

moving the hand-held part of the master control into the desired corresponding position, which includes manually moving the hand-held part and causing the hand-held part to be locked in position when its position is moved into a position in register with the desired corresponding position.

27. A method of establishing a desired orientational relationship between a hand-held part of a master control and an end effector of an associated slave as viewed in an image displayed on a viewer, the method including

causing the end effector to remain stationary;

determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with the viewer;

determining a current position of the end effector relative to the viewing end of the image capturing device operatively associated with the viewer;

determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer at which the desired orientational relationship would be established;

determining a desired corresponding position of the hand-held part of the master control relative to the viewer at which position a desired positional relationship between the hand-held part of the master control and the end effector would be established;

moving the hand-held part of the master control into the desired corresponding orientation; and

moving the hand-held part of the master control into the desired corresponding position, which includes manually moving the hand-held part and providing a signal to an operator manually moving the hand-held part when the hand-held part is moved into a position in register with the desired corresponding position.

28. A method of establishing a desired orientational relationship between a hand-held part of a master control and a surgical end effector of an associated surgical instrument slave in a telesurgical apparatus, the method including

causing the end effector to remain stationary;

determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with a viewer;

determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer at which the desired orientational relationship would be established; and

moving the hand-held part of the master control into the desired corresponding orientation by supplying electrical current to electrical motors associated with the hand-held part thereby to cause the hand-held part to be moved into the desired orientation.

29. A method as claimed in claim 28, in which the initial determining step includes computing the orientation relative to a reference coordinate frame positioned at the viewing end of the image capturing device.

30. A method as claimed in claim 29, which further includes defining a coordinate frame on the end effector, the orientation of the end effector then being defined by the orientation of the coordinate frame on the end effector relative to the reference coordinate frame.

31. A method as claimed in claim 29, in which determining the desired corresponding orientation of the hand-held part of the master control relative to the viewer includes computing an orientation of the hand-held part relative to a reference coordinate frame generally at the viewer.

32. A method as claimed in claim 31, in which computing the orientation of the hand-held part relative to the reference coordinate frame generally at the viewer includes defining a coordinate frame on the hand-held part, the orientation of the hand-held part then being defined by the orientation of the coordinate frame on the hand-held part relative to the reference coordinate frame at the viewer.

33. A method as claimed in claim 31, in which determining the desired corresponding orientation of the hand-held part includes determining an orientation of the hand-held part relative to the reference coordinate frame generally at the viewer which is the same as the orientation of the end effector relative to the reference coordinate frame at the image capturing device.

34. A method as claimed in claim 31, in which determining the desired corresponding orientation of the hand-held part includes determining an orientation of the hand-held part relative to the reference coordinate frame generally at the viewer which is offset relative to the orientation of the end effector relative to the reference coordinate frame at the image capturing device.

35. A method as claimed in claim 28, in which the master control has a plurality of configurations which yield the desired corresponding orientation, the method including computing a preferred configuration of the master control at which the hand-held part is at the desired corresponding orientation.

36. A method as claimed in claim 35, in which computing the preferred configuration includes examining a plurality of solutions corresponding to at least one segment of solutions.

37. A method as claimed in claim 36, in which examining the plurality of solutions of the segment includes selecting an arbitrary solution and then following an iterative procedure to compute the preferred solution.

38. A method as claimed in claim 37, in which following an iterative procedure to determine the preferred solution includes using a cost function.

39. A method as claimed in claim 38, in which the preferred solution relates to the solution having a lowest cost function value.

40. A method as claimed in claim 28, which further includes

determining a current position of the end effector relative to the viewing end of the image capturing device operatively associated with the viewer; and

determining a desired corresponding position of the hand-held part of the master control relative to the viewer at which position a desired positional relationship between the hand-held part of the master control and the end effector would be established; and

moving the hand-held part of the master control into the desired corresponding position.

41. A method as claimed in claim 40, in which determining the current position of the end effector relative to the viewing end of the image capturing device includes computing the position relative to a reference coordinate frame positioned at the viewing end of the image capturing device.

42. A method as claimed in claim 41, in which computing the position of the end effector relative to the reference coordinate frame at the viewing end of the image capturing device includes defining a coordinate frame on the end effector, the position of the end effector then being defined by the position of the coordinate frame on the end effector relative to the reference coordinate frame.

43. A method as claimed in claim 41, in which determining the desired corresponding position of the hand-held part of the master control relative to the viewer includes computing a position of the hand-held part relative to a reference coordinate frame generally at the viewer.

44. A method as claimed in claim 43, in which computing the position of the hand-held part relative to the reference coordinate frame generally at the viewer includes defining a coordinate frame on the hand-held part, the position of the hand-held part then being defined by the position of the coordinate frame on the hand-held part relative to the reference coordinate frame at the viewer.

45. A method as claimed in claim 43, in which determining the desired corresponding position of the hand-held part includes determining a position of the hand-held part relative to the reference coordinate frame generally at the viewer which is the same as the position of the end effector relative to the reference coordinate frame at the image capturing device.

46. A method as claimed in claim 43, in which determining the desired corresponding position of the hand-held part includes determining a position of the hand-held part relative to the reference coordinate frame generally at the viewer which is offset relative to the position of the end effector relative to the reference coordinate frame at the image capturing device.

47. A method as claimed in claim 40, in which moving the hand-held part of the master control into the desired corresponding position includes supplying electrical current to electrical motors associated with the hand-held part thereby to cause the hand-held part to be moved into the desired position.

48. A method as claimed in claim 40, in which moving the hand-held part of the master control into the desired corresponding position includes manually moving the hand-held part.

49. A method as claimed in claim 48, which further includes causing the hand-held part to be locked in position when its position is moved into a position in register with the desired corresponding position.

50. A method as claimed in claim 48, which further includes providing a signal to an operator manually moving the hand-held part when the hand-held part is moved into a position in register with the desired corresponding position.

51. A method of establishing a desired orientational relationship between a hand-held part of a master control and a surgical end effector of an associated surgical instrument slave in a telesurgical apparatus, the method including

causing the end effector to remain stationary;

determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with a viewer;

determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer at which the desired orientational relationship would be established; and

moving the hand-held part of the master control into the desired corresponding orientation by manually moving the hand-held part.

52. A method as claimed in claim 51, which further includes causing the hand-held part to be locked in position when its orientation is moved into an orientation in register with the desired corresponding orientation.

53. A method as claimed in claim 51, which further includes providing a signal to an operator manually moving the hand-held part when the hand-held part is moved into an orientation in register with the desired corresponding orientation.

54. A method of selecting a preferred angular position of a hand-held part of a master control about a roll axis thereof, which corresponds with a current angular position of an end effector about a roll axis thereof, where the hand-held part can have a plurality of angular positions spaced at 180°

intervals relative to each other which correspond with the current angular position of the end effector, the method including

determining the angular position of the end effector relative to an angular displacement range about its roll axis;

comparing the angular position of the end effector relative to its angular displacement range with the angular positions of the hand-held part, which correspond with the angular position of the end effector, relative to an angular displacement range of the hand-held part; and

selecting the angular position of the hand-held part relative to its angular displacement range which best mirrors the angular position of the end effector relative to its angular displacement range.

55. A method as claimed in claim 54, in which the hand-held part is orientationally adjustably mounted on an associated support, the end effector is orientationally adjustably mounted on an associated support, the method including the prior step of determining a desired orientation of the hand-held part which establishes a desired orientational relationship between the hand-held part and the end effector, the desired orientation of the hand-held part defining one of the corresponding angular positions of the hand-held part which corresponds to the current angular position of the end effector.

56. A method as claimed in claim 55, in which the comparing step includes imposing a simulated orientational change on the hand-held part which corresponds to a simulated orientational change of the end effector in moving its orientation into a predetermined reference orientation.

57. A method as claimed in claim 56, which includes determining a reference solution set of angular positions at 180°

intervals relative to each other for the simulated orientation of the hand-held part which correspond to the angular position of the end effector at its simulated predetermined reference orientation.

58. A method as claimed in claim 57, which includes comparing the current end effector angular position relative to its angular displacement range with the angular positions of the reference solution set relative to the angular displacement range of the hand-held part.

59. A method as claimed in claim 58, which includes selecting the angular position of the reference solution set relative to the angular displacement range of the hand-held part which best mirrors the current angular position of the end effector relative to its angular displacement range.

60. A method as claimed in claim 59, which includes predefining a solution branch of 360°

intervals and predefining another solution branch of 360°

intervals offset from the first solution branch by 180°

, the selected angular position defining one of the solution branches.

61. A method as claimed in claim 60, which includes comparing the defined solution branch and the selected angular position of the reference solution set with the angular positions of the hand-held part, which correspond with the current angular position of the end effector, relative to the angular displacement range of the hand-held part and selecting that angular position relative to the angular displacement range of the hand-held part which corresponds to the defined solution branch and which best mirrors the selected angular position of the reference solution set.

62. A surgical system comprising:

a master controller having a hand-held part and an actuator;

an end effector for manipulation of tissue;

a display showing an image of the end effector; and

a processor coupling the end effector to the master controller, the processor transmitting actuator signals to the actuator in response to an initial orientation of the hand-held part, the actuator moving the hand-held part from the initial orientation to a desired orientation in response to the actuator signals so that the hand-held part establishes a predetermined orientational relationship with the image of the end effector.

63. A surgical system as claimed in claim 62, wherein the processor

determines a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with a viewer; and

determines the desired corresponding orientation of the hand-held part of the master controller relative to the viewer at which the desired orientational relationship would be established.

64. A surgical system as claimed in claim 62, wherein the processor

determines a current position of the end effector relative to a viewing end of an image capturing device operatively associated with a viewer;

determines a desired corresponding position of the hand-held part of the master controller relative to the viewer at which position a desired positional relationship between the hand-held part of the master controller and the end effector would be established; and

transmits actuation signals to the actuator in response to an initial position of the hand-held part, the actuator moving the hand-held part from the initial position to a desired position in response to the actuator signals.

65. A surgical system as claimed in claim 62, wherein the processor

determines an angular position of the end effector relative to an angular displacement range about a roll axis thereof;

compares the angular position of the end effector relative to its angular displacement range with angular positions of the hand-held part of a master controller about a roll axis thereof, which correspond with the angular position of the end effector, relative to an angular displacement range of the hand-held part; and

selects the angular position of the hand-held part relative to its angular displacement range which best mirrors the angular position of the end effector relative to its angular displacement range.

66. A method of establishing a desired orientational relationship between a hand-held part of a master control and a surgical end effector of an associated surgical instrument slave in a telesurgical apparatus, the method including

causing the end effector to remain stationary;

determining a current orientation of the end effector relative to a viewing end of an image capturing device operatively associated with a viewer;

determining a desired corresponding orientation of the hand-held part of the master control relative to the viewer at which the desired orientational relationship would be established; and

moving the hand-held part of the master control into the desired corresponding orientation by supplying electrical current to electrical motors associated with the hand-held part.