Decoupled six degree-of-freedom robot manipulator

• US 5,710,870 A
• Filed: 09/07/1995
• Issued: 01/20/1998
• Est. Priority Date: 09/07/1995
• Status: Expired due to Term

• Current Assignee: California Institute of Technology, The Guillermo Rodriguez Revocable Trust
• Original Assignee: California Institute of Technology
• Inventors: Lee, Sukhan, Rodriguez, Guillermo, Barlow, Ed, Paljug, Eric, Charles, Steve, Ohm, Timothy, Schenker, Paul, Boswell, Curtis, Das, Hari
• Primary Examiner(s): Davis, George B.
• Application Number:
  US08/525,813
• Time in Patent Office: 866 Days
• Field of Search: 395/97, 395/98, 395/80, 395/86, 901/27, 901/30
• US Class Current: 700/263
• CPC Class Codes: A61B 2034/305 Details of wrist mechanisms at distal ends of robotic arms
• CPC Class Codes: A61B 2034/742 Joysticks
• 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 34/71 Manipulators operated by drive cable mechanisms
• CPC Class Codes: A61B 34/74 Manipulators with manual electric input means
• CPC Class Codes: A61B 34/77 Manipulators with motion or force scaling
• CPC Class Codes: B25J 13/02 Hand grip control means handles or pedals for crane control B66C13/56; for measuring the force applied to control members G01L5/22; hand-held casings for switching devices, e.g. joy-sticks H01H9/0214
• CPC Class Codes: B25J 17/0241 One-dimensional joints
• CPC Class Codes: B25J 19/02 Sensing devices
• CPC Class Codes: B25J 3/04 involving servo mechanisms servo-actuated heads B25J15/02
• CPC Class Codes: B25J 9/1045 comprising tensioning means
• CPC Class Codes: B25J 9/1607 Calculation of inertia, jacobian matrixes and inverses
• CPC Class Codes: B25J 9/1689 Teleoperation
• CPC Class Codes: G05B 2219/39457 Tendon drive
• CPC Class Codes: G05B 2219/41032 Backlash
• CPC Class Codes: G05B 2219/45123 Electrogoniometer, neuronavigator, medical robot used by surgeon to operate

Abstract

The present invention is a double-jointed, tendon-driven revolute joint, a decoupled tendon-driven wrist, an antibacklash mechanism, a robot control system, and a robot manipulator incorporating the double-jointed, tendon-driven revolute joint, decoupled tendon-driven wrist, and antibacklash mechanism. The robot manipulator is a microsurgical teleoperated robot with actuators located at an actuator base. The overall system architecture includes a slave robot manipulator coupled to an amplifier chassis which is coupled to a control chassis. The control chassis is coupled to a workstation with a graphical user interface. Components of the robot manipulator are categorized into a mechanical sub-system, an electronics sub-system, a servo-control sub-system, and a high-level software control sub-system.

Claims

1. A robot manipulator, comprising:

an actuator base with plural actuators;

an end effector;

plural arms extending seriatim between said end effector and said actuator base; and

plural joints connected between pairs of adjacent arms;

wherein each one of said plural joints comprises means for mechanically coupling respective ones of said actuators to respective ones of said joints through intermediate ones of said joints, and wherein said means for mechanically coupling is decoupled from said intermediate joints.

2. The invention as set forth in claim 1, wherein said means for mechanically coupling comprises:

a first keying drive component coupled to a second keying drive component;

a first passing drive component coupled to respective ones of said actuators for receiving rotational motion; and

a second passing drive component coupled to said first passing drive component for receiving said rotational motion from said first passing drive component and for transmitting said received rotational motion to one of said plural joints;

wherein said first and second keying drive components are constrained to rotate about one another to define an instantaneous center of rotation;

wherein said first passing drive component rotates with respect to said second passing drive component about said instantaneous center of rotation.

3. The invention as set forth in claim 2, wherein said first keying drive component is a first keying pulley and said second keying drive component is a second keying pulley.

4. The invention as set forth in claim 3, further comprising plural keying cables for rotatably coupling said first keying pulley to said second keying pulley and for rotationally constraining said first keying pulley to said second keying pulley so that said first and second keying pulleys rotate with respect to one another about said instantaneous center of rotation.

5. The invention as set forth in claim 2, wherein said first and second keying drive components are keying spur gears.

6. The invention as set forth in claim 2, wherein said first and second passing drive components are passing spur gears.

7. The invention as set forth in claim 2, wherein said first passing drive component is a first passing pulley and said second passing drive component is a second passing pulley.

8. The invention as set forth in claim 7, further comprising plural passing cables for rotatably coupling said first passing pulley to said second passing pulley and for rotationally constraining said first passing pulley to said second passing pulley so that said first and second passing pulleys rotate with respect to one another about said instantaneous center of rotation.

9. The invention as set forth in claim 1, wherein all actuators drives of said manipulator are located within said actuator base.

10. The invention as set forth in claim 1, wherein each of said joints comprises dual independent antibacklash drive transmission preloaded with respect to one another.

11. The invention as set forth in claim 1, wherein said plural joints further comprises an antibacklash mechanism for transmitting motion without backlash from respective ones of said plural actuator drives to respective ones of said joints, said antibacklash mechanism comprising:

at least a first transmission stage comprising first dual drive components, wherein both of said first dual drive components are rotatably coupled to said respective ones of said plural actuator drives and are independently rotatable with respect to one another; and

at least a second transmission stage comprising second dual drive reduction means, wherein each one of said second dual drive reduction means is rigidly attached to one of said first dual drive components and is rotatably coupled to said respective ones of said joints, whereby rotational motion of said respective ones of said plural actuator drives is transmitted through said first and second stages, to said respective ones of said joints without backlash.

12. A robot manipulator having an actuator and a plurality of decoupled joints, wherein each one of said decoupled joints comprises:

an input link having at least an input keying drive component rotatable on an input axis;

an output link coupled to said input link and having at least an output keying drive component rotatable on an output axis;

wherein said input and output keying drive components are constrained to rotate about one another to define an instantaneous center of rotation;

at least an input passing drive component rotatable on said input link and coupled to said actuator for receiving rotational motion; and

at least an output passing drive component rotatable on said output link and coupled to said input passing drive component for receiving said rotational motion decoupled from said one joint.

13. The invention as set forth in claim 12, wherein said input passing drive component rotates with respect to said output passing drive component about said instantaneous center of rotation.

14. The invention as set forth in claim 12, wherein said input keying drive component is an input keying pulley and said output keying drive component is an output keying pulley.

15. The invention as set forth in claim 14, further comprising plural keying cables for rotatably coupling said input keying pulley to said output keying pulley and for rotationally constraining said input keying pulley to said output keying pulley so that said input and output keying pulleys rotate with respect to one another about said instantaneous center of rotation.

16. The invention as set forth in claim 12, wherein said input and output keying drive components are keying spur gears.

17. The invention as set forth in claim 12, wherein said input and output passing drive components are passing spur gears.

18. The invention as set forth in claim 12, wherein said input passing drive component is an input passing pulley and said output passing drive component is an output passing pulley.

19. The invention as set forth in claim 18, further comprising plural passing cables for rotatably coupling said input passing pulley to said output passing pulley and for rotationally constraining said input passing pulley to said output passing pulley so that said input and output passing pulleys rotate with respect to one another about said instantaneous center of rotation.

20. The invention as set forth in claim 12, wherein said input and output links are coupled to each other by hinged side struts.

21. The invention as set forth in claim 12, wherein said input link further comprises plural input idler pulleys and said output link further comprises corresponding plural output idler pulleys, wherein each corresponding pair of said input and output idler pulleys drives one of said joints.

22. A robot manipulator having an actuator and a plurality of decoupled joints, wherein each one of said decoupled joints comprises:

an input link having an input keying pulley;

an output link coupled to said input link and having an output keying pulley;

a keying cable for rotatably coupling said input keying pulley to said output keying pulley, wherein said input and output keying pulleys are constrained to rotate about one another thereby defining an instantaneous center of rotation;

at least one input idler pulley rotatable on said input link and coupled to said actuator for receiving rotational motion;

at least one output idler pulley rotatable on said output link; and

at least one passing cable coupled to each input and output idler pulley for transmitting rotational motion of said input idler pulley and said output idler pulley decoupled from said one joint.

23. The invention as set forth in claim 22, wherein said input idler puller rotates with respect to said output idler pulley about said instantaneous center of rotation.

24. The invention as set forth in claim 22, wherein said input and output links are coupled to each other by hinged side struts.

25. The invention as set forth in claim 22, wherein said input and output links are displaced by at least a diameter of each of said input and output links to facilitate 180 degree rotation.

26. The invention as set forth in claim 22, wherein each of said joint'"'"'s rotation is dependant upon a ratio between said input and output keying pulleys'"'"' diameters.

27. The invention as set forth in claim 22, wherein all of said keying pulleys have the same diameter.

28. The invention as set forth in claim 22, wherein said input link further comprises plural input keying pulleys and said output link further comprises plural output keying pulleys.

29. An antibacklash mechanism for transmitting motion without backlash from an input rotating device to an output rotating device, said antibacklash mechanism comprising:

at least a first transmission stage comprising first dual drive components, wherein both of said first dual drive components are rotatably coupled to said input rotating device and are independently rotatable with respect to one another; and

at least a second transmission stage comprising second dual drive reduction means, wherein each one of said second dual drive reduction means is rigidly attached to one of said first dual drive components and is rotatably coupled to said output device, whereby rotational motion of said input rotating device is transmitted from said input device, through said first and second stages, to said output device without backlash.

30. The invention set forth in claim 29, wherein each of said first dual drive components is a spur gear.

31. The invention set forth in claim 29, wherein each of said second dual drive reduction means is a pinion gear.

32. The invention set forth in claim 29, wherein each of said second dual drive reduction means is rotatably coupled to said output device with a dual drive pulley.

33. The invention set forth in claim 29, further comprising means for preloading said first transmission stage relative to said second transmission stage in order to eliminate backlash.

34. The invention set forth in claim 33, further comprising means for locking said first and second transmission stages after said first and second transmission stages are preloaded.

35. A multiple degree of freedom robot having a plurality of arm joints, a wrist joint coupled to one of said arm joints and having a tip, and a computer control system, said computer control system comprising:

a user interface for receiving user commands;

a servo controller coupled to said arm and wrist joints for reading actual positions of said arm and wrist joints; and

a real-time kinematic processor coupled to said user interface and said servo controller for receiving said user commands and said actual positions of said arm and wrist joints for computing forward and inverse kinematic relationships for controlling said arm and wrist joints in accordance with said user commands and said computed relationships;

wherein said real-time kinematic processor comprising;

(a) means for setting a vector of tip displacements at said robot to zero,

(b) means for computing at each joint a displacement vector corresponding to a unit motion at a current joint,

(c) means for multiplying a displacement vector at said current joint by a transition matrix of a succeeding joint to produce a result,

(d) means for multiplying said result by a joint axis vector of said current joint,

(e) means for multiplying said result by said transition matrix to define a transition from a last joint to said tip,

(f) means for setting said vector as a respective column of a jacobian matrix, and

(g) means for multiplying a user defined vector of tip displacements by said jacobian matrix to compute corresponding joint angle displacements;

wherein said servo controller implements said joint angle displacements.

36. The invention as set forth in claim 35, wherein said means for setting said vector as a respective column of a jacobian matrix corresponds to an independent degree of freedom of each of said joints for each independent degree of freedom of said robot.

37. The invention as set forth in claim 35, wherein said robot further comprises means coupled between said servo controller and each of said joints for moving said joints robot in accordance with said joint angle displacements.

38. The invention as set forth in claim 35, wherein said real-time kinematic processor further comprises means for determining a set of joint coordinate displacements corresponding to a desired set of tip coordinate displacements, means for computing a jacobian matrix, and means for adding said jacobian matrix to said tip coordinate displacements to produce a corresponding joint coordinate displacement.

39. The invention as set forth in claim 35, wherein said real-time kinematic processor further comprises means for setting up and computing a transition matrix defining a position and rotation transition between successive joints of said robot, means for setting up vectors defining axes of rotation of each of said joint, and means for transforming each of said joint to a desired position and an orientation change of said tip from a world reference frame to a tip reference frame.

40. The invention as set forth in claim 39, wherein said means for multiplying a user defined vector of tip displacements by said jacobian matrix is constrained by said tip reference frame.

44. The invention as set forth in claim 40, wherein the setting said vector as a respective column of a jacobian matrix step corresponds to an independent degree of freedom of each of said joints for each independent degree of freedom of said robot.

41. A robot manipulator, comprising:

an actuator base with plural actuator drives;

a wrist with a tip;

plural arms extending seriatim between said wrist and said actuator base;

plural joints connected between pairs of adjacent arms;

wherein each of said plural joints comprises means for mechanically coupling respective ones of said actuators to respective ones of said joints through intermediate ones of said joints, and wherein said means for mechanically coupling is decoupled from said intermediate joints;

a user interface for receiving user commands;

a servo controller coupled to said arm and wrist joints for reading actual positions of said arm and wrist joints; and

a real-time kinematic processor coupled to said user interface and said servo controller for receiving said user commands and said actual positions of said arm and wrist joints for computing forward and inverse kinematic relationships for controlling said arm and wrist joints in accordance with said user commands and said computed relationships;

wherein said real-time kinematic processor comprising;

(a) means for setting a vector of tip displacements at said wrist to zero,

(b) means for computing at each joint a displacement vector corresponding to a unit motion at a current joint,

(c) means for multiplying a displacement vector at said current joint by a transition matrix of a succeeding joint to produce a result,

(d) means for multiplying said result by a joint axis vector of said current joint,

(e) means for multiplying said result by said transition matrix to define a transition from a last joint to said tip,

(f) means for setting said vector as a respective column of a jacobian matrix, and

(g) means for multiplying a user defined vector of tip displacements by said jacobian matrix to compute corresponding joint angle displacements;

wherein said servo controller implements said joint angle displacements.

42. The invention as set forth in claim 41, wherein said robot further comprises an antibacklash mechanism for transmitting motion without backlash from respective ones of said plural actuator drives to respective ones of said joints, said antibacklash mechanism comprising:

at least a first transmission stage comprising first dual drive components, wherein both of said first dual drive components are rotatably coupled to said respective ones of said plural actuator drives and are independently rotatable with respect to one another; and

at least a second transmission stage comprising second dual drive reduction means, wherein each one of said second dual drive reduction means is rigidly attached to one of said first dual drive components and is rotatably coupled to said respective ones of said joints, whereby rotational motion of said respective ones of said plural actuator drives is transmitted through said first and second stages, to said respective ones of said joints without backlash.

43. A method for manipulating a multiple degree of freedom robot having a plurality of arm joints, a wrist joint coupled to one of said arm joints and having a tip, a user interface for receiving user commands, a servo controller coupled to said arm and wrist joints for reading actual positions of said arm and wrist joints, said method comprising:

(a) determining a set of joint coordinate displacements corresponding to a desired set of tip coordinate displacements, computing a jacobian matrix, and adding said jacobian matrix to said tip coordinate displacements to produce a corresponding joint coordinate displacement by;

(1) setting up and computing a transition matrix defining a position and rotation transition between successive joints of said robot,

(2) setting up vectors defining axes of rotation of each of said joint,

(3) transforming to a desired position and an orientation change of said tip from a world reference frame to a tip reference frame;

(4) setting a vector of tip displacements at said robot to zero, computing at each joint a displacement vector corresponding to a unit motion at a current joint by multiplying a displacement vector at said current joint by a transition matrix of a succeeding joint to produce a result, multiplying said result by a joint axis vector of said current joint, multiplying said result by said transition matrix defining a transition from a last joint to said tip, and setting said vector as a respective column of a jacobian matrix, and

(5) multiplying a user defined vector of tip displacements by said jacobian matrix to compute corresponding joint angle displacements; and

(b) implementing said joint angle displacements by said servo controller in response to step (a).

45. The invention as set forth in claim 43, wherein the multiplying a user defined vector of tip displacements by said jacobian matrix step is constrained by said tip reference frame.

46. A multiple degree of freedom microsurgical robot manipulator, comprising:

a plurality of miniaturized decoupled robot joints comprising a plurality of arm joints each having a first keying pulley constrained to rotate about a second keying pulley, thereby defining an instantaneous center of rotation to effectuate one degree of freedom movement, and a miniaturized wrist joint coupled to one of said arm joints and having a tip and three degrees of freedom;

a plurality of miniaturized driving cables, each coupled an actuator drive at a proximal end and coupled to one of said joints at a distal end; and

a computer control system coupled to each of said robot actuator drives comprising;

(a) a servo-control sub-system for reading actual joint positions of said robot joints;

(b) a high level sub-system for receiving user commands from a user interface and for receiving actual joint positions from said servo sub-system, wherein said high level sub-system sends said user commands and said actual joint positions to a real-time kinematic processor having a forward kinematic processor and an inverse kinematic recursive processor for computing forward and inverse kinematic relationships of said joints;

(c) wherein said sub-system comprises means for determining a set of joint coordinate displacements corresponding to a desired set of tip coordinate displacements, means for computing a jacobian matrix, and means for adding said jacobian matrix to said tip coordinate displacements to produce a corresponding joint coordinate displacement;

(d) wherein said servo sub-system implements said joint coordinate displacements.

47. The invention as set forth in claim 46, wherein each of said actuator drives comprises a plurality of motors with rotational motion and having optical encoders for effecting micro-rotation of said motors and for transmitting said rotational motion of said motors to said driving cables.

48. The invention as set forth in claim 46, wherein said robot further comprises an antibacklash mechanism for transmitting motion without backlash from respective ones of said actuator drives to respective ones of said joints, said antibacklash mechanism comprising:

at least a first transmission stage comprising first dual drive components, wherein both of said first dual drive components are rotatably coupled to said respective ones of said actuator drives and are independently rotatable with respect to one another; and

at least a second transmission stage comprising second dual drive reduction means, wherein each one of said second dual drive reduction means is rigidly attached to one of said first dual drive components and is rotatably coupled to said respective ones of said joints, whereby rotational motion of said respective ones of said actuator drives is transmitted through said first and second stages, to said respective ones of said joints without backlash.

49. The invention as set forth in claim 46, wherein said real-time kinematic processor comprises:

a) means for setting a vector of tip displacements at said wrist to zero;

(b) means for computing at each joint a displacement vector corresponding to a unit motion at a current joint;

(c) means for multiplying a displacement vector at said current joint by a transition matrix of a succeeding joint to produce a result;

(d) means for multiplying said result by a joint axis vector of said current joint;

(e) means for multiplying said result by said transition matrix to define a transition from a last joint to said tip;

(f) means for setting said vector as a respective column of a jacobian matrix; and

(g) means for multiplying a user defined vector of tip displacements by said jacobian matrix to compute corresponding joint angle displacements.

50. The invention as set forth in claim 46, further comprising plural keying cables for rotatably coupling said first keying pulley to said second keying pulley and for rotationally constraining said first keying pulley to said second keying pulley so that said first and second keying pulleys rotate with respect to one another about said instantaneous center of rotation.

51. The invention as set forth in claim 46, wherein said first and second keying pulleys are keying spur gears.

52. The invention as set forth in claim 46, wherein said first and second passing drive components are passing spur gears.

53. The invention as set forth in claim 46, further comprising:

a first passing drive component coupled to said driving cables of respective ones of said actuators for receiving rotational motion; and

a second passing drive component coupled to said first passing drive component for receiving said rotational motion from said first passing drive component and for transmitting said received rotational motion to one of said joints;

wherein said first passing drive component rotates with respect to said second passing drive component about said instantaneous center of rotation.

54. The invention as set forth in claim 53, wherein said first passing drive component is a first passing pulley and said second passing drive component is a second passing pulley.

55. The invention as set forth in claim 54, further comprising plural passing cables for rotatably coupling said first passing pulley to said second passing pulley and for rotationally constraining said first passing pulley to said second passing pulley so that said first and second passing pulleys rotate with respect to one another about said instantaneous center of rotation.

56. The invention as set forth in claim 46, further comprising an input link coupled between each of said first keying pulley and each of said robot arm joints, and an output link coupled between each of said second keying pulley and each of said robot arm joint.

57. The invention as set forth in claim 56, wherein said input link further comprises plural input keying pulleys and said output link further comprises plural output keying pulleys.

58. The invention as set forth in claim 57, wherein said input link further comprises plural input passing pulleys and said output link further comprises corresponding plural output passing pulleys, wherein each corresponding pair of said input and output passing pulleys drives one of said joints.

59. The invention as set forth in claim 57, wherein said input and output links are coupled to each other by hinged side struts.

60. The invention as set forth in claim 46, wherein said computer control system further comprises:

a manual joint module, an auto joint module, a forward kinematic module, an inverse kinematic module, a sum joints module, a control joints module, and a servo-controller module;

means for receiving user commands by said manual joint module for changing joint angles and positions of each of said robot joints for a particular computation cycle; and

means for receiving user commands by said auto joint module for starting, stopping, and selecting combinations of movement of said joints for changing joint angles and said position of each of said robot joints for a particular computation cycle.

61. The invention as set forth in claim 60, further comprising:

means for receiving said joint angles and positions from said auto joints module by said control joints module for limiting said joint angles sent to said servo-controller; and

means for receiving said joint angles and positions from said sum joints module by said servo-controller module, for reading actual angles and positions of said robot joints, and for sending said actual angles and positions to said servo controller for controlling said robot joints.

62. The invention as set forth in claim 61, further comprising:

means for receiving said robot joint angles from said control joints module and said servo controller module by said forward kinematic module for computing a forward kinematic relationship of said robot joints;

means for receiving a portion of said forward kinematic relationship from said forward kinematic module by said inverse kinematic module for computing an inverse kinematic relationship of said robot joints in order to determine changes in said robot joint angles.

63. The invention as set forth in claim 62, further comprising:

means for receiving said changes in joint angles and positions from said inverse kinematic module and said actual joint angle positions from said servo controller module by said sum joints module for computing a sum of said desired change in said joint angle positions and current joint angle positions.

64. The invention as set forth in claim 63, further comprising:

means for receiving user commands and a portion of said forward kinematic relationship by said manual cartesian module for computing a cartesian position change of said robot tip and for changing a position of each of said cartesian position and orientation of said robot tip for a particular computation cycle;

means for receiving user commands and a portion of said forward kinematic relationship by said auto cartesian module for starting, stopping and selecting combinations of tip coordinates and for computing a change in said robot tip position and orientation in order to continuously move said selected tip coordinates and for changing a position of each of said robot tip coordinates for each cycle; and

means for receiving data from said manual and auto cartesian modules for computing and sending a difference between said desired tip position and said actual tip position and a difference between said desired tip orientation and said actual tip orientation to said inverse kinematic module.