CONTROL SYSTEM AND METHOD FOR A PROSTHETIC KNEE

• US 20100185124A1
• Filed: 01/22/2010
• Published: 07/22/2010
• Est. Priority Date: 03/10/2004
• Status: Active Grant

• Current Assignee: Ossur Engineering Incorporated
• Original Assignee: Ossur Engineering Incorporated
• Inventors: Elliott, Scott B., Oddson, Magnús, Bisbee, Charles R. III
• Granted Patent: US 8,617,254 B2
• Time in Patent Office: Days
• US Class Current: 600/595
• 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 2002/5033 for adjusting damping damping means A61F2002/5003
• CPC Class Codes: A61F 2002/6863 magnetic magnetic prosthetic parts A61F2002/30079
• CPC Class Codes: A61F 2002/704 computer-controlled, e.g. robotic control
• CPC Class Codes: A61F 2002/705 Electromagnetic data transfer for implantable prostheses A61F2250/0002
• 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 2002/764 for measuring acceleration
• CPC Class Codes: A61F 2250/0034 differing in viscosity

Abstract

A prosthetic or orthotic system including a magnetorheological (MR) damper. The MR damper may be configured to operate in shear mode. In one embodiment, the MR damper includes a rotary MR damper. A controller is configured to operate the damper. A mobile computing device may be adapted to intermittently communicate configuration parameters to the controller. A method of configuring a prosthetic or orthotic system is also disclosed.

Claims

1. A device configured to be attached to a limb, comprising:

an actuator configured to control movement of the limb;

at least one sensor configured to measure motion of the limb;

at least one processor configured to execute software instructions stored on a computer-readable medium, said processor configured to;

identify a control state based at least partly on the measure of motion;

send a control signal to the actuator based at least partly on the control state; and

filter a value of the control signal based at least partly on values of previous control signals.

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

3. The device of claim 1, wherein the at least one sensor comprises a knee angle sensor.

4. The device of claim 1, wherein the at least one sensor comprises a load sensor.

5. The device of claim 4, wherein the load sensor comprises at least one strain gauge.

6. The device of claim 1, wherein the control signal comprises a current and wherein the actuator is configured to vary resistance to rotation in response to the current.

7. The device of claim 1, wherein the processor is configured to apply a fixed point infinite impulse response filter to filter the value of the control signal.

8. The device of claim 1, wherein the processor is further configured to adjust parameters for identifying the control state.

11. The device of claim 1, wherein the processor is configured to filter increases to said control signal differently than decreases to said control signal.

9. The device of claim 9, wherein the processor is further configured to adjust parameters for identifying the control state in response to receiving a signal instructing the processor to adaptively adjust the parameters during operation of the device.

10. The device of claim 9, wherein the parameters comprise target values for the at least one characteristic of prosthetic movement.

12. A method of controlling a prosthetic having a movement damper, comprising:

measuring at least one characteristic of prosthetic movement;

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

applying a fixed point infinite impulse response filter to filter the damping value based at least partly on values of previous damping values; and

applying the damping value to control the resistance of a damper.

13. The method of claim 12, wherein applying the damping value comprising applying the damping value to a rotary magnetorheological damper operating in shear mode.

14. The method of claim 12, wherein measuring the at least one characteristic of prosthetic movement comprises measuring a knee angle.

15. The method of claim 12, wherein measuring the at least one characteristic of prosthetic movement comprises measuring load using a load sensor.

16. The method of claim 15, wherein the load sensor comprises at least one strain gauge.

17. The method of claim 12, wherein the damping value is indicative of a current and wherein the damper is configured to vary resistance to rotation in response to the current.

18. The method of claim 12, further comprising adjusting parameters for identifying the control state.

19. The method of claim 18, wherein adjusting parameters for identifying the control state is in response to receiving a signal instructing the processor to adaptively adjust the parameters during operation of the device.

20. The method of claim 18, wherein the parameters comprise target values for the at least one characteristic of prosthetic movement.

21. The method of claim 12, wherein filtering comprises filtering increases to said control signal differently than decreases to said control signal.