Speed-adaptive and patient-adaptive prosthetic knee

• US 7,279,009 B2
• Filed: 08/22/2003
• Issued: 10/09/2007
• Est. Priority Date: 03/29/2000
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Herr, Hugh M., Wilkenfeld, Ari, Bleck, Olaf
• Primary Examiner(s): Willse; David
• Assistant Examiner(s): Blanco; Javier G.
• Application Number:
  US10/646,097
• Publication Number:
  US 20040039454A1
• Time in Patent Office: 1,509 Days
• Field of Search: None
• US Class Current: 623/44
• CPC Class Codes: A61B 5/1038 Measuring plantar pressure during gait
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take precedence
• CPC Class Codes: A61F 2/64 Knee joints
• CPC Class Codes: A61F 2/70 electrical
• CPC Class Codes: A61F 2002/5003 having damping means, e.g. shock absorbers for implantable joints A61F2002/30563
• CPC Class Codes: A61F 2002/5004 operated by electro- or magnetorheological fluids
• CPC Class Codes: A61F 2002/6818 for braking
• 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: F16F 9/535 Magnetorheological [MR] fluid dampers springs comprising magnetorheological [MR] elastomers F16F1/361

Abstract

The invention relates to an automated speed-adaptive and patient-adaptive control scheme and system for a knee prosthesis. The control scheme and system utilizes sensory information measured local to the prosthesis to automatically adjust stance and swing phase knee resistances to a particular wearer under a wide variety of locomotory activities. Advantageously, no patient-specific information needs to be pre-programmed into the prosthetic knee by a prosthetist or the patient. The system is able to adapt to various types of disturbances once the patient leaves the prosthetist'"'"'s facility because it is patient-adaptive and speed-adaptive.

Claims

1. A method of controlling a prosthetic knee system, comprising:

measuring at least one characteristic of knee movement;

calculating a damping value based at least partly on the at least one measured characteristic; and

applying the damping value to control a resistance of a magnetorheological damper operating primarily in shear mode, wherein said damping is created primarily by shear forces.

2. The method of claim 1, wherein the magnetorheological damper operating primarily in shear mode comprises a rotary magnetorheological damper operating primarily in shear mode.

3. The method of claim 1, wherein the measuring comprises receiving a value from a knee angle sensor.

4. The method of claim 1, wherein the measuring comprises receiving a value from a load sensor.

5. The method of claim 4, wherein receiving a value from the load sensor comprises receiving at least one value from a strain gauge.

6. The method of claim 1, wherein the calculating comprises adapting a damping parameter.

7. The method of claim 1, further comprising identifying a control state based at least partly on the at least one measured characteristic of knee movement, and calculating a damping value based at least partly on the control state.

8. A prosthetic knee system, comprising:

a magnetorheological damper configured to provide damping to a prosthetic knee, wherein said damping is created primarily by shear forces;

at least one sensor configured to measure knee motion; and

a software system configured to send a control signal to the damper based at least partly on the knee motion measured by the at least one sensor.

9. The system of claim 8, wherein the magnetorheological damper comprises a rotary magnetorheological damper.

10. The system of claim 8, wherein the at least one sensor comprises a knee angle sensor.

11. The system of claim 8, wherein the at least one sensor comprises a load sensor.

12. The system of claim 11, wherein the load sensor comprises at least one strain gauge.

13. The system of claim 8, wherein the control signal comprises a current and wherein the damper is configured to vary resistance to rotation in response to the current.

14. The system of claim 8 wherein the software system is configured to identify a control state based at least partly on the measure of knee motion and configured to send a control signal to the damper based at least partly on the control state.

15. A method of controlling a prosthetic joint system, comprising:

measuring at least one characteristic of joint movement;

identifying a control state from a plurality of distinct, predetermined control states based at least partly on the at least one measured characteristic of joint movement;

calculating a damping value based at least partly on the control state; and

applying the damping value to control a resistance of a magnetorheological damper, wherein said damping is created primarily by shear forces.

16. The method of claim 15, wherein each of the predetermined control states corresponds to a phase of the gait.

17. The method of claim 15, wherein the prosthetic joint system comprises a prosthetic knee.

18. The method of claim 17, wherein the magnetorheological damper operates primarily in shear mode.

19. The method of claim 15, wherein the measuring comprises receiving a value from an angle sensor.

20. The method of claim 15, wherein the measuring comprises receiving a value from a load sensor.

21. The method of claim 15, wherein the calculating comprises adapting a damping parameter.

22. A prosthetic joint system, comprising:

a magnetorheological damper configured to provide damping to a prosthetic joint, wherein said damping is created primarily by shear forces;

at least one sensor configured to measure joint motion; and

a software system configured to identify a control state from a plurality of distinct, predetermined control states based at least partly on the measure of joint motion and configured to send a control signal to the damper based at least partly on the control state.

23. The system of claim 22, wherein each of the predetermined control states corresponds to a phase of the gait.

24. The system of claim 22, comprising a prosthetic knee.

25. The system of claim 22, wherein the magnetorheological damper operates primarily in shear mode.

26. The system of claim 22, wherein the at least one sensor comprises an angle sensor.

27. The system of claim 22, wherein the at least one sensor comprises a load sensor.

28. The system of claim 22, wherein the control signal comprises a current and wherein the damper is configured to vary resistance to rotation in response to the current.