Semi-actuated transfemoral prosthetic knee

• US 20100023133A1
• Filed: 06/16/2009
• Published: 01/28/2010
• Est. Priority Date: 06/16/2008
• Status: Active Grant

• Current Assignee: Ekso Bionics, Inc. (Ekso Bionics Holdings, Inc.), Regents of the University of California (University of California)
• Original Assignee: Berkeley Bionics Co., Regents of the University of California (University of California)
• Inventors: Pillai, Minerva Vasudevan, Schwartz, Miclas, Kruse, Sebastian, Fairbanks, Dylan Miller, Lambrecht, Bram Gilbert Antoon, Rosa, Matthew, Harding, Nathan, Kazerooni, Homayoon, Zoss, Adam Brian
• Granted Patent: US 8,231,688 B2
• Time in Patent Office: Days
• US Class Current: 623/24
• CPC Class Codes: A61F 2/64 Knee joints
• CPC Class Codes: A61F 2/70 electrical
• CPC Class Codes: A61F 2/74 fluid , i.e. hydraulic or pneumatic
• CPC Class Codes: A61F 2/741 using powered actuators, e.g. stepper motors or solenoids
• CPC Class Codes: A61F 2/744 Vane- or curved-cylinder type actuators, e.g. actuators using rotary pistons
• CPC Class Codes: A61F 2/748 Valve systems
• CPC Class Codes: A61F 2/80 Sockets, e.g. of suction type
• CPC Class Codes: A61F 2002/30359 Pyramidally- or frustopyramidally-shaped protrusion and recess
• CPC Class Codes: A61F 2002/701 operated by electrically controlled means, e.g. solenoids or torque motors
• CPC Class Codes: A61F 2002/704 computer-controlled, e.g. robotic control
• CPC Class Codes: A61F 2002/7625 for measuring angular position
• CPC Class Codes: A61F 2002/7635 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61F 2002/7645 for measuring torque, e.g. hinge or turning moment, moment of force
• CPC Class Codes: A61F 2220/0033 made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit

Abstract

A semi-actuated above knee prosthetic system, which is mostly passive in nature and includes a shank link coupled to an artificial foot, a knee mechanism connected to the shank link and a thigh link attached to an above-knee remaining lower limb of an amputee, is operable in either an actuated mode or an un-actuated mode controlled by a signal processor linked to various prosthetic mounted sensors. In the actuated mode, power is delivered to a torque generator connected to the knee mechanism to cause a forced movement between the thigh and shank links. In the un-actuated mode, a control circuit operates in a non-powered manner to allow operation of the knee mechanism with modulated resistance. Power is delivered through an electric motor connected to a battery source and employed to drive a hydraulic pump which is part of an overall hydraulic power unit including the torque generator.

Claims

1. A semi-actuated prosthetic knee device, configured to be coupled to an above-knee remaining lower limb of an amputee and operable in both actuated and un-actuated modes, comprising:

a shank link adapted to be coupled to an artificial foot;

a thigh link configured to be attached to an above-knee remaining lower limb of an amputee;

a knee mechanism interconnecting said thigh link and said shank link, said knee mechanism allowing flexion and extension movements of said thigh link and said shank link relative to each other;

a hydraulic torque generator interposed between said shank link and said thigh link;

a hydraulic power unit including a hydraulic valve circuit hydraulically coupled to said torque generator, a hydraulic pump, and an electric motor mechanically coupled to said hydraulic pump;

a power source for providing electric power to said electric motor;

at least one sensor for sensing an operation associated with one of said shank link, said thigh link and said knee mechanism; and

a signal processor connected to the power source and the hydraulic power unit for controlling operation of the hydraulic power unit based on signals received from the at least one sensor wherein, when said semi-actuated prosthetic knee operates in its actuated mode, electric power is transferred from said power source to said electric motor to drive the hydraulic pump to provide working fluid to said torque generator under control of the signal processor in order to create a torque between said shank link and said thigh link and, when said semi-actuated prosthetic knee operates in its un-actuated mode, said hydraulic valve circuit modulates a resistance of fluid flow in said torque generator such that said semi-actuated prosthetic knee operates without any transfer of electric power from said electric power source to said electric motor.

2. The device of claim 1 wherein said semi-actuated prosthetic knee is operable in a power regenerative mode in which said hydraulic pump hydraulically couples to said torque generator and at least a portion of hydraulic flow from said torque generator flows to said hydraulic pump causing said electric motor to turn and generate electric power.

3. The device of claim 1 wherein said hydraulic valve circuit comprises a first controllable valve and a pump valve serially connected to each other, said hydraulic pump being coupled to two ports of said first controllable valve and to said pump valve, and said torque generator being coupled to two ports of said first controllable valve wherein, when said semi-actuated prosthetic knee operates in its actuated mode, said pump valve does not close, allowing said signal processor to control said torque generator by controlling said electric motor and, when said semi-actuated prosthetic knee operates in its un-actuated mode, said first controllable valve modulates the resistance of the fluid flow in said torque generator.

4. The device of claim 3, wherein when said semi-actuated prosthetic knee operates in said un-actuated mode, said pump valve is either fully or partially closed.

5. The device of claim 3, wherein said semi-actuated prosthetic knee is operable in a power regenerative mode in which said pump valve is not closed, allowing at least a portion of fluid flow from said torque generator to turn said hydraulic pump and a motor controller applies a non-zero current onto said electric motor to resist the fluid flow in said hydraulic pump.

6. The device of claim 3, wherein said hydraulic valve circuit further comprises a first check valve installed in series with said first controllable valve, allowing said first controllable valve to modulate the resistance of the fluid flow in said torque generator in one direction only.

7. The device of claim 6, wherein said hydraulic valve circuit further comprises a second controllable valve installed in parallel with both said first controllable valve and said first check valve.

8. The device of claim 6, wherein said hydraulic valve circuit further comprises a second controllable valve and a second check valve installed in series relative to each other and installed in parallel with each of said first controllable valve and said first check valve.

9. The device of claim 1, wherein said hydraulic valve circuit comprises a first controllable valve and an actuator valve serially connected to each other, said torque generator being coupled to two ports of said first controllable valve and said actuator valve, and said hydraulic pump is coupled to two ports of said first controllable valve wherein, when said semi-actuated prosthetic knee operates in its actuated mode, said first controllable valve is closed and said actuator valve is not closed, allowing said signal processor to control said torque generator by controlling said electric motor and, when said semi-actuated prosthetic knee operates in an un-actuated mode, said actuator valve modulates the resistance of fluid flow in said torque generator.

10. The device of claim 9, wherein said semi-actuated prosthetic knee is operable in a power regenerative mode in which said actuator valve is not closed, allowing at least a portion of fluid flow from said torque generator to turn said hydraulic pump and a motor controller applies a non-zero current onto said electric motor to resist the fluid flow in said hydraulic pump.

11. The device of claim 9, wherein said hydraulic valve circuit further comprises a first check valve installed in series with said first controllable valve allowing a modulation of the resistance of the fluid flow in said torque generator in one direction only.

12. The device of claim 11, wherein said hydraulic valve circuit further comprises a second controllable valve installed in parallel with both said first controllable valve and said first check valve.

13. The device of claim 11, wherein said hydraulic valve circuit further comprises a second controllable valve and a second check valve installed in series relative to each other and installed in parallel with each of said first controllable valve and said first check valve.

14. The device of claim 1, wherein said hydraulic valve circuit comprises a three-way valve having first, second and third ports, said hydraulic pump being coupled to the first and second ports of said three-way valve and said torque generator being coupled to the second and third ports of said three-way valve wherein, when said semi-actuated prosthetic knee operates in its actuated mode, said three-way valve blocks said second port and connects said first port to said third port allowing for fluid flow between said hydraulic pump and said torque generator, and when said semi-actuated prosthetic knee operates in an un-actuated mode, said three-way valve blocks said first port and modulates an opening of said third port to modulate the resistance of the fluid flow through said torque generator.

15. The device of claim 14, wherein said semi-actuated prosthetic knee is operable in a power regenerative mode in which said three-way valve connects said first port to said third port allowing at least a portion of the fluid flow from said torque generator to turn said hydraulic pump and a motor controller applies a non-zero current onto said electric motor to resist the fluid flow in said hydraulic pump.

16. The device of claim 14, further comprising:

a check valve installed on said second port of said three-way valve.

17. The device of claim 1, wherein said hydraulic valve circuit comprises a three-way valve having first, second and third ports, said hydraulic pump being coupled to the first and second ports of said three-way valve and said torque generator being coupled to a third port and said second port wherein, when said semi-actuated prosthetic knee operates in its actuated mode, said three-way valve blocks said second port and connects said first port to said third port allowing for fluid flow between said hydraulic pump and said torque generator and, when said semi-actuated prosthetic knee operates in its un-actuated mode, said three-way modulates an opening of said third port thereby modulating the resistance of the fluid flow in said torque generator.

18. The device of claim 17, further comprising:

a check valve installed on said second port of said three-way valve.

19. The device of claim 1, wherein said at least one sensor comprises a stance sensor adapted to identify if the artificial foot is in contact with a support surface.

20. The device of claim 19, wherein said stance sensor comprises a force-torque sensor installed on said shank link measuring both force and moment in a sagittal plane.

21. The device of claim 1, wherein the at least one sensor comprises an angle sensor generating a knee angle signal representing the angle between said shank link and said thigh link.

22. The device of claim 20, wherein the at least one sensor comprises a thigh angle sensor generating a thigh angle signal representing the absolute angle of said thigh link.

23. The device of claim 1, wherein the at least one sensor comprises two pressure sensors respectively measuring hydraulic fluid pressure in first and second chambers of said torque generator.

24. A prosthetic knee device, configured to be coupled to an above-knee remaining lower limb of an amputee having a trunk, comprising:

an artificial foot having a toe and a heel;

a shank link coupled to the artificial foot;

a thigh link configured to be attached to an above-knee remaining lower limb of an amputee;

a knee mechanism interconnecting said thigh link and said shank link, said knee mechanism allowing flexion and extension movements of said thigh link and said shank link relative to each other;

a torque generator configured to generate torque between said shank link and said thigh link;

a knee angle sensor creating a knee angle signal representing the angle between said shank link and said thigh link;

a stance sensor capable of identifying which part of said artificial foot is in contact with ground;

a power source capable of providing electric power; and

a signal processor connected to the power source, the torque generator and each of the knee angle and stance sensors, wherein said signal processor receives signals from the knee and stance sensors, determines an estimated location of the artificial foot with respect to the trunk of the amputee and establishes a swing state when said artificial foot leaves the ground based on the estimated location.

25. The device of claim 24 wherein said signal processor begins to implement a stance state when said stance sensor indicates that said artificial foot has contacted the ground.

26. The device of claim 25 wherein, during a portion of said stance state, said prosthetic knee operated in an un-actuated mode.

27. The device of claim 25 wherein, during a portion of said stance state, said prosthetic knee resists flexion.

28. The device of claim 25 wherein, during a portion of said stance state, said signal processor causes resistance in the knee mechanism through said torque generator.

29. The device of claim 25 wherein, when said stance sensor indicates that the heel of said artificial foot is taking more load than the toe of said artificial foot, said signal processor signals for a greater resistance through said torque generator than when said stance sensor indicates that the toe of said artificial foot is taking more load than the heel of said artificial foot.

30. The device of claim 24 wherein said signal processor begins to implements a forward swing state when said artificial foot leaves the ground generally behind at least a portion of the trunk of the amputee.

31. The device of claim 30 wherein, during a portion of said forward swing state, said signal processor controls the angle between said shank link and said thigh link such that said artificial foot follows a predetermined trajectory.

32. The device of claim 30 wherein, during a portion of said forward swing state, said signal processor controls the angle between said shank link and said thigh link as a function of said thigh angle signal such that said artificial foot follows a predetermined trajectory.

33. The device of claim 24 wherein said signal processor initiates a reverse swing state when said artificial foot leaves the ground in front of the trunk of the amputee.

34. The device of claim 33 wherein, during a portion of said reverse swing state, said signal processor controls the angle between said shank link and said thigh link as a function of said thigh angle signal such that said artificial foot follows a predetermined trajectory.

35. The device of claim 33 wherein, during a portion of said reverse swing state, said signal processor controls the angle between said shank link and said thigh link such that said artificial foot follows a predetermined trajectory.

36. The device of claim 24 wherein said signal processor begins to implements an ascent swing state when said artificial foot leaves the ground generally beneath the trunk of the amputee.

37. The device of claim 36 wherein, during a portion of said ascent swing state, said signal processor controls the angle between said shank link and said thigh link.

38. The device of claim 37 wherein, during a portion of said ascent swing state, said signal processor controls the angle between said shank link and said thigh link as a function of said-thigh angle signal such that said artificial foot follows a predetermined trajectory.

39. The device of claim 24 wherein said signal processor begins to implement an ascent stance state when said stance sensor indicates that said artificial foot contacted the ground with a substantially bent knee angle.

40. The device of claim 39 wherein, during a portion of said ascent stance state, said signal processor controls the angle between said shank link and said thigh link.

41. The device of claim 39 wherein, during a portion of said ascent stance state, said signal processor controls torque generated by said torque generator.

42. The device of claim 39 wherein, during a portion of said ascent stance state, said signal processor controls a speed of said torque generator.

43. The device of claim 24 wherein the torque generator includes multiple chambers and the device further comprising:

a pressure sensor for the torque generator, wherein said signal processor implements a descent stance state when said artificial foot is in contact with the ground and said pressure sensor indicates a large pressure difference between the multiple chambers of said torque generator.

44. The device of claim 43 wherein, during a portion of said descent stance state, said prosthetic knee operates in an un-actuated mode.

45. The device of claim 43 wherein, during a portion of said descent stance state, said prosthetic knee resists flexion.

46. The device of claim 24, wherein said signal processor begins to implement a descent swing state when said stance sensor indicates that said artificial foot leaves the ground behind the trunk of the amputee.

47. The device of claim 46 wherein, during a portion of said descent swing state, said signal processor controls the angle between said shank link and said thigh link.

48. The device of claim 46 wherein, during a portion of said descent swing state, said signal processor controls the angle between said shank link and said thigh link as a function of said thigh angle signal such that said artificial foot follows a predetermined trajectory.

49. The device of claim 24 wherein said signal processor implements a sitting state when said signal processor learns that, during said descent stance state, said artificial foot just separated from the ground and is positioned in front of the trunk of the amputee.

50. The device of claim 49 wherein, during a portion of said sitting state, said prosthetic knee operates in an un-actuated mode.

51. The device of claim 49 wherein, during a portion of said sitting state, said prosthetic knee is caused to flex smoothly with little or no resistance.

52. The device of claim 24 wherein said signal processor begins to implements a rising state when, during a sitting state, said stance sensor indicates that said artificial foot is contacting the ground generally beneath the trunk of the amputee.

53. The device of claim 52 wherein, during a portion of said rising state, said signal processor controls the angle between said shank link and said thigh link.

54. The device of claim 52 wherein, during a portion of said rising state, said signal processor controls an amount of torque generated by said torque generator.

55. The device of claim 52 wherein, during a portion of said rising stance state, said signal processor controls a current to an electric motor coupled to said torque generator.

56. The device of claim 52 wherein, during a portion of said rising stance state, said signal processor controls a speed of said torque generator.

57. A semi-actuated prosthetic knee device, configured to be coupled to an above-knee remaining lower limb of an amputee and operable in both actuated and un-actuated modes, comprising:

a shank link adapted to be coupled to an artificial foot;

a thigh link configured to be attached to an above-knee remaining lower limb of an amputee;

a knee mechanism interconnecting said thigh link and said shank link, said knee mechanism allowing flexion and extension movements of said thigh link and said shank link relative to each other;

a hydraulic torque generator including torque generator ports, said hydraulic torque generator being configured to generate torque between said shank link and said thigh link;

a hydraulic power unit having first and second paths of connecting said torque generator ports, with the first path being through a hydraulic pump which is mechanically coupled to an electric motor and the second path being through a hydraulic valve circuit;

a power source capable of providing electric power to said electric motor;

a stance sensor capable of identifying which part of said artificial foot is in contact with the ground; and

a signal processor receiving signals from the stance sensor and controlling said electric motor wherein, when said semi-actuated prosthetic knee operates in its actuated mode, said torque generator ports are coupled to said hydraulic pump and, when said semi-actuated prosthetic knee operates in an un-actuated mode, said semi-actuated prosthetic knee is configured such that the said torque generator ports are coupled to said hydraulic valve circuit.

58. The device of claim 57 wherein, during said un-actuated mode, said hydraulic valve circuit modulates a resistance of fluid flow in said torque generator allowing said semi-actuated prosthetic knee device to operate without any transfer of power from said power source to said electric motor.

59. The device of claim 57 wherein, during said actuated mode, said semi-actuated prosthetic knee is configured such that power is transferred from said power source to said electric motor and said hydraulic pump hydraulically couples to said torque generator, with said signal processor controlling said torque generator.

60. The device of claim 57 wherein said hydraulic valve circuit comprises a first controllable valve wherein, when said semi-actuated prosthetic knee operates in an un-actuated mode, said first controllable valve modulates a resistance of fluid flow in said torque generator.

61. The device of claim 60 where said hydraulic valve circuit further comprises a first check valve installed in series with said first controllable valve allowing said first controllable valve to modulate the resistance of fluid flow in said torque generator in one direction only.

62. The device of claim 61 where said hydraulic valve circuit further comprises a second controllable valve installed in parallel with said first controllable valve and said first check valve.

63. The device of claim 61 where said hydraulic valve circuit further comprises a second controllable valve and a second check valve installed in series relative to each other and installed in parallel with said first controllable valve and said first check valve.

64. The device of claim 57 wherein said hydraulic valve circuit includes a three-way valve having first, second and third ports, said pump being coupled to the first and second ports of said three-way valve and said torque generator being coupled to the second and third ports wherein, when said semi-actuated prosthetic knee operates in its un-actuated mode, said three-way valve blocks said first port.

65. The device of claim 64 wherein, when said semi-actuated prosthetic knee operates in its actuated mode, said three-way valve allows for fluid flow between said hydraulic pump and said torque generator.

66. A semi-actuated prosthetic knee device, configured to be coupled to an above-knee remaining lower limb of an amputee having a trunk and operable in both actuated and un-actuated modes, comprising:

an artificial foot having a toe and a heel;

a shank link coupled to the artificial foot;

a thigh link configured to be attached to an above-knee remaining lower limb of an amputee;

a knee mechanism interconnecting said thigh link and said shank link, said knee mechanism allowing flexion and extension movements of said thigh link and said shank link relative to each other;

a hydraulic torque generator including torque generating ports, said hydraulic torque generator being interposed and configured to generate torque between said shank link and said thigh link;

a hydraulic power unit including a hydraulic valve circuit hydraulically coupled to said torque generator, a hydraulic pump, and an electric motor mechanically coupled to said hydraulic pump, said hydraulic power unit having first and second paths of connecting said torque generating ports, with the first path being through the hydraulic pump which is mechanically coupled to the electric motor and the second path being through the hydraulic valve circuit;

a power source for providing electric power to said electric motor;

at least one sensor provided on one of said shank link, said thigh link and said knee mechanism for sensing operational parameters of the prosthetic knee, said at least one sensor including a knee angle sensor creating a knee angle signal representing the angle between said shank link and said thigh link and a stance sensor capable of identifying which part of said artificial foot is in contact with ground; and

a signal processor connected to the power source, the torque generator, each of the knee and stance sensors and the hydraulic power unit for controlling operation of the hydraulic power unit based on signals received from the at least one sensor wherein;

when said semi-actuated prosthetic knee operates in its actuated mode, electric power is transferred from said power source to said electric motor to drive the hydraulic pump to provide working fluid to said torque generator under control of the signal processor in order to create a torque between said shank link and said thigh link and, when said semi-actuated prosthetic knee operates in its un-actuated mode, said hydraulic valve circuit modulates a resistance of fluid flow in said torque generator such that said semi-actuated prosthetic knee operates without any transfer of electric power from said electric power source to said electric motor;

said signal processor receives signals from the knee and stance sensors, determines an estimated location of the artificial foot with respect to the trunk of the amputee and establishes a swing state when said artificial foot leaves the ground based on the estimated location; and

signal processor receives signals from the stance sensor and controls said electric motor wherein, when said semi-actuated prosthetic knee operates in its actuated mode, said torque generator ports are coupled to said hydraulic pump and, when said semi-actuated prosthetic knee operates in an un-actuated mode, said semi-actuated prosthetic knee is configured such that the said torque generator ports are coupled to said hydraulic valve circuit.