MULTI-PLY STRAP DRIVE TRAINS FOR ROBOTIC ARMS

• US 20070089557A1
• Filed: 12/15/2006
• Published: 04/26/2007
• Est. Priority Date: 09/30/2004
• Status: Active Grant

• Current Assignee: Intuitive Surgical Operations, Inc. (Intuitive Surgical Holdings, LLC)
• Original Assignee: Intuitive Surgical Operations, Inc. (Intuitive Surgical Holdings, LLC)
• Inventors: Cooper, Thomas, Solomon, Todd
• Granted Patent: US 9,261,172 B2
• Time in Patent Office: Days
• US Class Current: 74/490.10
• CPC Class Codes: A61B 2017/00845 of moving parts with respect to each other
• CPC Class Codes: A61B 2034/305 Details of wrist mechanisms at distal ends of robotic arms
• CPC Class Codes: A61B 2034/715 Cable tensioning mechanisms for removing slack
• CPC Class Codes: A61B 34/30 Surgical robots
• CPC Class Codes: A61B 34/37 Master-slave robots A61B34/35 takes precedence
• CPC Class Codes: A61B 34/71 Manipulators operated by drive cable mechanisms
• CPC Class Codes: A61B 90/361 Image-producing devices, e.g. surgical cameras
• CPC Class Codes: B25J 18/00 Arms
• CPC Class Codes: B25J 18/005 having a curved shape
• CPC Class Codes: B25J 18/007 the end effector rotating around a fixed point
• CPC Class Codes: B25J 9/1045 comprising tensioning means
• CPC Class Codes: F16H 7/20 Mountings for rollers or pulleys
• CPC Class Codes: Y10S 901/21 Flaccid drive element
• CPC Class Codes: Y10T 29/49455 Assembly
• CPC Class Codes: Y10T 29/49826 Assembling or joining
• CPC Class Codes: Y10T 74/20305 Robotic arm
• CPC Class Codes: Y10T 74/20323 including flaccid drive element

Abstract

In one embodiment of the invention, a robotic arm is provided including a linkage assembly and a strap drive train. The linkage assembly includes first, second, third, and fourth links pivotally coupled in series together at first, second, and third joints to define a parallelogram with an insertion axis. The strap drive train includes first and second sets of straps coupled to the linkage assembly. As the linkage assembly is moved about a pitch axis, the first set of straps ensures the third link maintains the same angle relative to the first link, and the first and second set of straps ensures the fourth link maintains the same angle relative to the second link.

Claims

1. A robotic arm comprising:

a linkage assembly including first, second, third, and fourth links pivotally coupled in series together at first, second, and third joints to define a parallelogram with an insertion axis;

a strap drive train including first and second sets of straps coupled to the linkage assembly; and

wherein as the linkage assembly is moved about a pitch axis, the first set of straps ensures the third link maintains the same angle relative to the first link, and the first and second sets of straps ensures the fourth link maintains the same angle relative to the second link.

2. The robotic arm of claim 1, wherein

the first link includes a first joint pulley rigidly coupled thereto,

the third link includes a second joint pulley rigidly coupled thereto, and

the first set of straps connect the first joint pulley to the second joint pulley in a one-to-one ratio.

3. The robotic arm of claim 2, wherein

the second link includes a third joint pulley rigidly coupled thereto, the third joint pulley concentric with but independent of the second joint pulley to pivot independently,

the fourth link includes a fourth joint pulley rigidly coupled thereto, and

the second set of straps connect the third joint pulley to the fourth joint pulley in a one-to-one ratio.

4. The robotic arm of claim 1, wherein

the third link is bent and includes at least one idler pulley to direct at least one strap of the second set of straps through the third link.

5. The robotic arm of claim 3, wherein

the third link includes a bend and at least one idler pulley pivotally coupled to the third link near the bend, and

a first strap of the second set of straps connecting the third joint pulley to the fourth joint pulley, the first strap rides over the at least one idler pulley to navigate around the bend in the third link.

6. The robotic arm of claim 3, wherein

a first end of each of a second strap and a third strap of the second set of straps is wrapped around the at least one idler pulley in opposite directions,

a second end of the second strap wrapped around the third joint pulley in an opposite direction to a first end of the first strap, and

a second end of the third strap wrapped around the fourth joint pulley in an opposite direction to a second end of the first strap.

7. The robotic arm of claim 6, wherein

each strap of the second set of straps are formed of multiple plies of metal.

8. The robotic arm of claim 7, wherein

the multiple plies of metal at one end of at least one strap of the second set of straps is joined together by a tab.

9. The robotic arm of claim 7, wherein

the multiple plies of metal at one end of at least one strap of the second set of straps is joined together by a tensioning block to tension the second set of straps.

10. The robotic arm of claim 3, wherein

a first end of a second strap of the second set of straps is wrapped around the third joint pulley in an opposite direction to a first end of the first strap,

a second end of the second strap wrapped around the fourth joint pulley in an opposite direction to a second end of the first strap,

the first strap rides over a first idler pulley, and

the second strap is reverse bent over a second idler pulley concentric with but independent of the first idler pulley to pivot in an opposite direction.

11. The robotic arm of claim 10, wherein

the first strap is formed of multiple plies of metal, and

the second strap is formed of alternating layers of metal and an antifriction material such that the metal layers sandwich the layers of antifriction material.

12. The robotic arm of claim 10, wherein

the multiple plies of metal at one end of the first strap are joined together by a first tab;

and

the alternating layers of metal and an antifriction material at one end of the second strap are joined together by a second tab.

13. The robotic arm of claim 1, further comprising:

a drive mount pivotally coupled to the first link of the linkage assembly, the drive mount to mount the robotic arm to a patient side system, the drive mount including a motor to yaw the linkage assembly about a yaw axis.

14. A robotic arm comprising:

a serial linkage pivotally coupled in series together including

an offset yaw link having a first joint pulley rigidly coupled thereto,

a drive link having a second joint pulley rigidly coupled thereto,

a bent link having a third joint pulley rigidly coupled thereto and an idler pulley, the third joint pulley independent of and concentric with the second joint pulley, and

an instrument holder link having a fourth joint pulley rigidly coupled thereto;

a strap drive train including

a first strap and a second strap in the drive link coupled between the first joint pulley and the third joint pulley;

a third strap in the bent link coupled between the second joint pulley and the fourth joint pulley over the idler pulley;

a fourth strap in the bent link coupled between the second joint pulley and the idler pulley, and

a fifth strap in the bent link coupled between the idler pulley and the fourth joint pulley; and

wherein the serial linkage and the strap drive train to constrain the motion of a shaft of a tool to a center of rotation.

15. The robotic arm of claim 14, wherein

the offset yaw link to support and pivot the drive link, the bent link, and the instrument holder link together about a yaw axis.

16. The robotic arm of claim 15, further comprising:

a drive mount pivotally coupled to the offset yaw link of the serial linkage, the drive mount to mount the robotic arm to a patient side system, the drive mount including a motor to yaw the serial linkage about the yaw axis.

17. The robotic arm of claim 14, wherein

the drive link further includes at least one motor to pitch the serial linkage about a pitch axis

18. The robotic arm of claim 14, wherein

each of the straps are formed of multiple plies of metal.

19. A robotic arm comprising:

a serial linkage pivotally coupled in series together including

an offset yaw link having a first joint pulley rigidly coupled thereto,

a drive link having a second joint pulley rigidly coupled thereto,

a bent link having a third joint pulley rigidly coupled thereto and first and second idler pulleys, the third joint pulley independent of and concentric with the second joint pulley, the first idler pulley independent of and concentric with the second idler pulley, and

an instrument holder link having a fourth joint pulley rigidly coupled thereto;

a strap drive train including

a first strap and a second strap in the drive link coupled between the first joint pulley and the third joint pulley;

a third strap in the bent link coupled between the second joint pulley and the fourth joint pulley over the first idler pulley;

a fourth strap in the bent link coupled between the second joint pulley and the fourth joint pulley reverse bent over the second idler pulley with ends wrapped around the joint pulleys in an opposite direction to that of ends of the third strap; and

wherein the serial linkage and the strap drive train to constrain the motion of a shaft of a tool to a center of rotation.

20. The robotic arm of claim 19, wherein

the first, second, and third straps are each formed of multiple plies of metal, and

the fourth strap is formed of alternating layers of metal and an antifriction material such that the metal layers sandwich the layers of antifriction material.

21. A method for a robotic arm, the method comprising:

pitching a linkage assembly including first, second, third, and fourth links coupled in series together with a strap drive train coupled thereto, the linkage assembly defining a parallelogram with an insertion axis;

ensuring the third link maintains the same angle relative to the first link in response to the pitching of the linkage assembly; and

ensuring the fourth link maintains the same angle relative to the second link in response to the pitching of the linkage assembly.

22. The method of claim 21, wherein

the first link is pivotally coupled to a mounting base;

and

prior to pitching the linkage assembly the method further includes mounting the mounting base to a patient side cart.

23. The method of claim 22, wherein

the mounting base includes a motor to yaw the linkage assembly;

and the method further includes yawing the linkage assembly.

24. A method for a robotic arm, the method comprising:

coupling first, second, third, and fourth links in series together at respective first, second, and third joints to form a linkage assembly;

coupling a strap drive train to the linkage assembly;

calibrating the linkage assembly to substantially eliminate remote center error and define a parallelogram.

25. The method of claim 24, wherein

the linkage assembly is calibrated by adjusting the strap drive train.

26. The method of claim 25, wherein

the strap drive train is adjusted to rotate the fourth link about the third joint to calibrate a length in a long side of the parallelogram.

27. The method of claim 26, wherein

the strap drive train is adjusted to rotate the third link about the second joint to substantially eliminate the remote center error.

28. A method for a robotic arm, the method comprising:

adjusting a strap drive train to rotate an instrument holder link about a joint to calibrate a length in a long side of a parallelogram;

adjusting the strap drive train to rotate a main link about a joint to substantially eliminate a remote center error;

verifying that the length in the long side of the parallelogram is calibrated; and

verifying that the remote center error is substantially eliminated.

29. The method of claim 28, wherein

the remote center error has been substantially eliminated if a pitched remote center lays on a yaw axis of the robotic arm.

30. The method of claim 28, wherein

the length in the long side of the parallelogram is calibrated if it is set to a correct length.

31. The method of claim 28, wherein

the strap drive train is adjusted by

lengthening a first strap coupled between joint pulleys, and

shortening a second strap coupled between the joint pulleys.

32. The method of claim 31, wherein

the first strap is effectively lengthened by loosening a first tensioning screw of a first tensioning block at an end of the first strap, and

the second strap is effectively shortened by tightening a second tensioning screw of a second tensioning block at an end of the second strap.

33. A robotic arm comprising:

a linkage assembly including a plurality of links pivotally coupled in series together at one or more joints to slidingly support a tool along an insertion axis, the plurality of links including a first pulley and a second pulley;

at least one strap coupled between the first pulley and the second pulley to drive the linkage assembly; and

a strap tensioning system coupled to the at least one strap, the strap tensioning system to tension the at least one strap.

34. The robotic arm of claim 33, wherein

the at least one strap is formed of multiple plies of metal generating a spring force to keep the tab locked into the first pocket of the first pulley and the tensioning block locked into the second pocket of the second pulley to avoid complete collapse of the arm if the at least one strap is slackened.

35. The robotic arm of claim 33, wherein

the strap tensioning system includes

a swing arm tensioner to adjust the tension in the at least one strap by applying a force thereto;

and

an idler pulley pivotally coupled to the swing arm tensioner, the idler pulley to ride on the at least one strap.

36. The robotic arm of claim 35, wherein

the strap tensioning system further includes

one or more swing arm sensors to detect if the at least one strap slackens or breaks.

37. The robotic arm of claim 35, wherein

the swing arm tensioner includes

a mounting base,

a pivotal shaft coupled to the mounting base,

an arm with a first end pivotally coupled to the pivotal shaft,

a spring coupled between the mounting base and the arm, and

a pulley shaft coupled to a second end of the arm and the idler pulley.

38. The robotic arm of claim 37, wherein

the swing arm tensioner further includes

a fastener to lock a position of the arm of the swing arm tensioner with respect to the mounting base.

39. The robotic arm of claim 37, wherein

the swing arm tensioner further includes

a brake to lock a position of the arm of the swing arm tensioner with respect to the mounting base.

40. The robotic arm of claim 39, wherein

the brake is an electronically engagable brake controlled by a computer.

41. The robotic arm of claim 33, wherein

the strap tensioning system includes

the first pulley having a first pocket;

the second pulley having a second pocket; and

the at least one strap including

a tab coupled to a first end, the tab to hook into the first pocket of the first pulley to couple the first end of the at least one strap thereto, and

a tensioning block coupled to a second end, the tensioning block to hook into the second pocket of the second pulley to couple the second end of the at least one strap thereto.

42. The robotic arm of claim 41, wherein

in the strap tensioning system,

the first pulley further has a first recess in a portion of its circumference joining the first pocket to receive the first end of the at least one strap, a first stop at a front of the first pocket to couple to a front side of the tab, a first side restraining protrusion extending from the first stop to retain the tab in the first pocket, and a first lip at the back of the first pocket to further retain the tab in the first pocket;

and

the second pulley further has a second recess in a portion of its circumference joining the second pocket to receive the second end of the at least one strap, a second stop at a front of the second pocket to couple to a front side of the tensioning block, a second side restraining protrusion extending from the second stop to retain the tensioning block in the second pocket, and a second lip at the back of the second pocket to further retain the tensioning block in the second pocket.

43. The robotic arm of claim 42, wherein

the strap tensioning system further includes

a tensioning fastener to tension the at least one strap, and wherein

the tensioning block has an opening with threads, and

the second pulley further has a cutout and an opening into the second pocket to receive the tensioning fastener and allow the tensioning fastener to mate with the threaded opening in the tensioning block.

44. The robotic arm of claim 43, wherein

the strap tensioning system further includes

a screw-lock heli-coil in the threaded opening of the tensioning block to keep the tensioning fastener from rotating and changing tension on the at least one strap.

45. The robotic arm of claim 43, wherein

the strap tensioning system further includes

a locking fastener to keep the tensioning fastener from backing out on its own and reducing the tension on the at least one strap, and

the second pulley further has a threaded opening to receive the locking fastener and couple it against the tensioning fastener.

46. The robotic arm of claim 33, wherein

the strap tensioning system includes

the first pulley having a first pocket;

the second pulley having a second pocket; and

the at least one strap including

a tab coupled to a first end, the tab to hook into the first pocket of the first pulley to couple the first end of the at least one strap thereto, and

a hooked tab coupled to a second end, the hooked tab having a first hook to couple the second end of the at least one strap to the second pulley.

47. The robotic arm of claim 46, wherein

the strap tensioning system further includes

a tensioning block with a second hook to mate with the first hook of the hooked tab, the tensioning block has an opening with threads,

a tensioning fastener to tension the at least one strap, and wherein

the second pulley further has a second recess in a portion of its circumference joining the second pocket to receive the second end of the at least one strap, a second stop at a front of the second pocket to couple to a front side of the tensioning block, a second side restraining protrusion extending from the second stop to retain the tensioning block in the second pocket, a second lip at the back of the second pocket to further retain the tensioning block in the second pocket, and a cutout and an opening into the second pocket to receive the tensioning fastener and allow the tensioning fastener to mate with the threaded opening in the tensioning block.

48. The robotic arm of claim 47, wherein

the strap tensioning system further includes

a screw-lock heli-coil in the threaded opening of the tensioning block to keep the tensioning fastener from rotating and changing tension on the at least one strap.

49. The robotic arm of claim 47, wherein

the strap tensioning system further includes

a locking fastener to keep the tensioning fastener from backing out on its own and reducing the tension on the at least one strap, and

the second pulley further has a threaded opening to receive the locking fastener and couple it against the tensioning fastener.

50. A strap drive train for a robotic arm, the strap drive train comprising:

a first pulley with a first pocket;

a second pulley with a second pocket; and

a first multi-ply strap coupled between the first pulley and the second pulley, the first multi-ply strap including

a first coupler coupled to a first end, the first coupler hooked into the first pocket of the first pulley to couple the first end of the first multi-ply strap thereto,

a second coupler coupled to a second end, the second coupler hooked into the second pocket of the second pulley to couple the second end of the first multi-ply strap thereto,

wherein the first coupler and the second coupler are each selected from the group consisting of a tab, a hooked tab, and a tensioning block.

51. The strap drive train of claim 50, wherein:

the first pulley further has a third pocket;

the second pulley further has a fourth pocket; and

the strap drive train further includes a second multi-ply strap coupled between the first pulley and the second pulley opposite the first multi-ply strap, the second multi-ply strap including

a third coupler coupled to a first end, the third coupler hooked into the third pocket of the first pulley to couple the first end of the second multi-ply strap thereto,

a fourth coupler coupled to a second end, the fourth coupler hooked into the fourth pocket of the second pulley to couple the second end of the second multi-ply strap thereto,

wherein the third coupler and the fourth coupler are each selected from the group consisting of a tab, a hooked tab, and a tensioning block.

52. The strap drive train of claim 51, wherein

the first multi-ply strap and the second multi-ply strap are formed of multiple plies of metal generating a spring force to keep the couplers locked into the pockets of the pulleys to avoid complete collapse of the arm if the first or second strap is slackened.

53. A strap guide bearing system comprising:

a mounting block to couple to a link;

a pair of spaced apart roller bearings rotatably coupled to the mounting block substantially in parallel to each other, the pair of spaced apart roller bearings to straddle a strap and maintain proper tracking of the strap; and

an anti-friction mechanism coupled to the mounting block, the anti-friction mechanism to reduce abrasion of the strap straddled between the pair of spaced apart roller bearings.

54. The strap guide bearing system of claim 53, wherein

the anti-friction mechanism is an anti-friction pad coupled to the mounting block.

55. The strap guide bearing system of claim 53, wherein

the anti-friction mechanism is a roller rotationally coupled to the mounting block and parallel to a width of the strap.

56. The strap guide bearing system of claim 53, further comprising:

one or more fasteners to couple the mounting block to the link.

57. The strap guide bearing system of claim 53, further comprising:

a pair of dowel pins to rotatably couple the pair of roller bearings to the mounting block, respectively.

58. A method in a link of a robotic arm, the method comprising:

mounting a first strap guide bearing system to a link such that a first pair of roller bearings to straddle a strap;

laterally guiding sides of the strap to maintain tracking of the strap on a first pulley; and

wherein ordinarily a first gap exist between the strap and an anti-friction mechanism of the first strap guide system.

59. The method of claim 58, further comprising:

if the first gap becomes substantially zero, reducing abrasion on the strap by the anti-friction mechanism providing a low coefficient of friction.

60. The method of claim 59, wherein

the anti-friction mechanism further presses back on the strap to reduce abrasion.

61. The method of claim 58, wherein

the anti-friction mechanism is an anti-friction pad.

62. The method of claim 58, wherein

the anti-friction mechanism is a roller parallel to a width of the strap.

63. The method of claim 58, further comprising:

mounting a second strap guide bearing system to the link such that a second pair of roller bearings to straddle the strap;

laterally guiding sides of the strap to maintain tracking of the strap on a second pulley; and

wherein ordinarily a second gap exist between the strap and an anti-friction mechanism of the second strap guide system.

64. A camber adjustable pulley system comprising:

a bracket to mount the camber adjustable pulley system to a link, the bracket having a first pivot valley;

a first pivotable pulley mount having a first pivot point mounted in the first pivot valley of the bracket, the first pivot point to pivot the first pivotable pulley mount in the bracket,

a first pulley rotatably coupled to the first pivotable pulley mount; and

a first camber adjustment mechanism coupled to the bracket and the first pivotable pulley mount, the first camber adjustment mechanism to adjust the first pivotable pulley mount to set the camber of the first pulley;

wherein the first pivot point is substantially near a first pulley axis of the first pulley.

65. The camber adjustable pulley system of claim 64, wherein

the first camber adjustment mechanism is a first camber adjustment screw inserted through a first opening in the bracket and threaded into the first pivotable pulley mount.

66. The camber adjustable pulley system of claim 65, further comprising:

a first snap ring around the first camber adjustment screw between the bracket and the first pivotable pulley mount, the first snap ring to retain the first camber adjustment screw in the first opening in the bracket; and

a first spring washer around the first camber adjustment screw between the bracket and the first pivotable pulley mount, the first spring washer to apply pressure to force away the first pivotable pulley mount from the bracket against the first camber adjustment screw.

67. The camber adjustable pulley system of claim 64, further comprising

a first bearing rotatably coupled between the first pulley and the first pivotable pulley mount, the first bearing to rotatably couple the first pulley to the first pivotable pulley mount.

68. The camber adjustable pulley system of claim 64, wherein

the bracket further has a second pivot valley spaced apart from the first pivot valley;

and the camber adjustable pulley system further comprises;

a second pivotable pulley mount having a second pivot point mounted in the second pivot valley of the bracket, the second pivot point to pivot the second pivotable pulley mount in the bracket,

a second pulley rotatably coupled to the second pivotable pulley mount; and

a second camber adjustment mechanism coupled to the bracket and the second pivotable pulley mount, the second camber adjustment mechanism to adjust the second pivotable pulley mount to set the camber of the second pulley;

wherein the second pivot point is substantially near a second pulley axis of the second pulley.

69. A method in a link of a robotic arm, the method comprising:

rotatably supporting a first pulley in a bracket, the first pulley to rotate about a first axis;

setting a first adjustment mechanism to pivot the first pulley in the bracket and tilt the first axis;

wherein the first adjustment mechanism sets the camber of the first pulley.

70. The method of claim 69, further comprising:

rotatably supporting a second pulley in the bracket, the second pulley to rotate about a second axis;

setting a second adjustment mechanism to pivot the second pulley in the bracket and tilt the second axis;

wherein the second adjustment mechanism sets the camber of the second pulley different from the camber of the first pulley.

71. The method of claim 69, wherein

the setting of the first adjustment mechanism pivoting a first pivotable pulley mount against the bracket, the first pivotable pulley mount rotatably coupled to the first pulley to pivot the first pulley in the bracket.

72. The method of claim 69, further comprising:

maintaining the camber setting of the first pulley in the bracket.

73. The method of claim 72, wherein

the camber setting of the first pulley is maintained by

deterring movement in the first adjustment mechanism that pivots the first pulley in the bracket.

74. The method of claim 70, further comprising:

maintaining the camber settings of the first pulley and the second pulley in the bracket.

75. The method of claim 74, wherein

the camber settings of the first pulley and the second pulley are maintained by

deterring movement in the first adjustment mechanism that pivots the first pulley in the bracket;

and

deterring movement in the second adjustment mechanism that pivots the second pulley in the bracket.