Powered Ankle-Foot Prosthesis

• US 20140088729A1
• Filed: 08/19/2013
• Published: 03/27/2014
• Est. Priority Date: 03/31/2005
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Herr, Hugh M., Weber, Jeff A., Au, Kwok Wai Samuel, Deffenbaugh, Bruce Wayne, Aisen, Benjamin B., Magnusson, Lee Harris, Hofmann, Andreas G.
• Granted Patent: US 10,137,011 B2
• Time in Patent Office: Days
• US Class Current: 623/50
• CPC Class Codes: A61F 2/60 Artificial legs or feet or parts thereof
• CPC Class Codes: A61F 2/605 Hip joints
• CPC Class Codes: A61F 2/64 Knee joints
• CPC Class Codes: A61F 2/6607 Ankle joints
• CPC Class Codes: A61F 2/68 Operating or control means
• CPC Class Codes: A61F 2002/5004 operated by electro- or magnetorheological fluids
• CPC Class Codes: A61F 2002/503 for adjusting elasticity, flexibility, spring rate or mechanical tension
• CPC Class Codes: A61F 2002/5033 for adjusting damping damping means A61F2002/5003
• CPC Class Codes: A61F 2002/5075 Multiple spring systems including two or more helical springs
• CPC Class Codes: A61F 2002/6818 for braking
• 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 2002/764 for measuring acceleration
• CPC Class Codes: A61F 2002/7645 for measuring torque, e.g. hinge or turning moment, moment of force
• CPC Class Codes: B25J 19/0008 Balancing devices

Abstract

A powered ankle-foot prosthesis, capable of providing human-like power at terminal stance that increase amputees metabolic walking economy compared to a conventional passive-elastic prosthesis. The powered prosthesis comprises a unidirectional spring, configured in parallel with a force-controllable actuator with series elasticity. The prosthesis is controlled to deliver the high mechanical power and net positive work observed in normal human walking.

Claims

1-4. -4. (canceled)

5. An autonomous, wearable powered leg prosthetic, orthotic or exoskeletal device, comprising:

a) a controllable actuator that is spannable across a joint to thereby apply torque about the joint;

b) at least one sensor selected from the group consisting of a position, velocity, acceleration, force and torque sensor, to thereby establish sensory information of the device;

c) at least one electromyograhic sensor to sense an electromyograhic signal from a leg muscle of a person wearing the device; and

d) a controller coupled to the actuator and the sensors, whereby the controller employs the sensory information to drive the actuator and thereby cause the device to execute one of a plurality of selectable gait patterns, the controller configured to control at least one of position, torque and impedance of the joint according to the selected gait pattern and to switch among the selectable gait patterns in response to sensing of the electromyograhic signal by the electromyograhic sensor.

6. The powered device of claim 5, wherein the joint is an ankle joint.

7. The powered device of claim 6, wherein the sensory information includes at least one member of the group consisting of a foot contact, ankle angle, and ankle torque.

8. The powered device of claim 5, further including the joint, the joint being a mechanical joint.

9. The powered device of claim 5, wherein the actuator includes a series elastic actuator, the series elastic actuator including a motor, a spring connected in series with the motor, and a transmission coupled to the motor and the spring.

10. The powered device of claim 5, wherein the gait patterns include level ground walking and stair descent.

11. The powered device of claim 5, wherein the controller includes an electromyographic processing unit coupled to the electromyographic sensor, whereby the electromyographic processing unit receives the sensed electromyograhic signal from the electromyographic sensor and provides a control command to cause the controller to switch between the gait patterns.

12. The powered device of claim 11, wherein the electromyographic processing unit includes a pre-processing unit to process the sensed electromyograhic signal received from the electromyographic sensor.

13. The powered device of claim 12, wherein the electromyographic processing unit further includes a neural network to determine the control command from the processed electromyograhic signal.

14. The powered device of claim 13, wherein the control command is an angle of the joint.

15. The powered device of claim 5, wherein the controller includes at least one finite state controller corresponding to at least one of the gait patterns.

16. An autonomous, wearable powered leg device, comprising:

a) a controllable actuator linkable to an ankle joint to thereby impart torque about the joint; and

b) an electromyographic processing unit linked to the controllable actuator, the electromyographic processing unit connectable to limb muscles, whereby an individual wearing the device can modulate the controllable actuator to adjust at least one of ankle position and ankle impedance.

17. The device of claim 16, further including the ankle joint, the joint being a mechanical joint.

18. The device of claim 17, wherein the joint has a rotational joint bearing axis, which joint defines an angle between two structures that are joined by the joint, which angle can vary over a range of angles during normal operation of the device.

19. The device of claim 16, further including a sensory system linked to the controllable actuator, the sensory system including at least one sensor at or proximate to the joint.

20. The device of claim 16, wherein the electromyographic processing unit is used to switch among a plurality of selected gait patterns selected by the individual.

21. The device of claim 16, further including a plurality of servo controllers, at least one of which links the electromyographic processing unit to the controllable actuator during normal operation of the device.

22. The device of claim 21, wherein the servo controllers include:

a) a torque controller that provides an offset torque during powered plantar flexion push-off;

b) an impedance controller that modulates at least one of joint stiffness and damping during a stance phase of a gait of the individual; and

c) a position controller that controls foot position during a swing phase of the gait of the individual.

23. The device of claim 22, further including a controller that determines which servo controller is employed to execute a gait selected by the individual among distinct gaits.

24. The device of claim 23, wherein the controller includes at least one finite state controller corresponding to at least one of the distinct gaits.

25. A method of controlling an autonomous, wearable powered leg prosthetic, orthotic or exoskeletal device, the method comprising the steps of:

a) sensing, with at least one sensor selected from the group consisting of a position, velocity, acceleration, force and torque sensor of the device, to thereby establish sensory information of the device;

b) sensing, with an electromyographic sensor, a myoelectric signal from a limb muscle of a person wearing the device to establish sensory information of the person;

c) employing the sensory information of at least one of the device and the person to drive a controllable actuator of the prosthetic device and thereby cause the device to execute one of a plurality of selectable gait patterns; and

d) transitioning between the gait patterns in response to the sensory information of the person.