Variable mechanical-impedance artificial legs

• US 8,551,184 B1
• Filed: 02/01/2012
• Issued: 10/08/2013
• Est. Priority Date: 07/15/2002
• Status: Active Grant

• Current Assignee: Otto Bock HealthCare LP (Nader Holding GmbH & Co. KG)
• Original Assignee: iWalk Incorporated (Ottobock SE & Co. KGaA)
• Inventors: Herr, Hugh M.
• Primary Examiner(s): Willse, David H
• Assistant Examiner(s): BLANCO, JAVIER G
• Application Number:
  US13/363,820
• Time in Patent Office: 615 Days
• Field of Search: None
• US Class Current: 623/24
• CPC Class Codes: A61F 2/60 Artificial legs or feet or parts thereof
• CPC Class Codes: A61F 2/602 with air cushions A61F2/7843 takes precedence
• CPC Class Codes: A61F 2/64 Knee joints
• CPC Class Codes: A61F 2/66 Feet; Ankle joints
• CPC Class Codes: A61F 2/6607 Ankle joints
• CPC Class Codes: A61F 2/74 fluid , i.e. hydraulic or pneumatic
• CPC Class Codes: A61F 2002/5007 having elastic means different from springs, e.g. including an elastomeric insert elastic coating A61F2002/3007; springs A61F2002/5072; plate-like springs for feet A61F2002/6657
• 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 2002/6614 Feet
• CPC Class Codes: A61F 2002/6621 Toes
• CPC Class Codes: A61F 2002/6845 Clutches
• CPC Class Codes: A61F 2005/0134 with two orthogonal pivots
• CPC Class Codes: A61F 2005/0169 with damping means
• CPC Class Codes: A61F 5/01 Orthopaedic devices, e.g. splints, casts or braces

Abstract

In one aspect, the invention provides methods and apparatus facilitating an adjustable-stiffness prosthesis or orthosis (including approximations to arbitrarily definable non-linear spring functions). Spring rates may be varied under no-load conditions during a walking gate cycle to minimize power consumption. In another aspect, the invention provides methods and apparatus for outputting positive power from a prosthesis or orthosis, facilitating high-performance artificial limbs. In one embodiment of the invention, the positive power is transferred from a functioning muscle to the prosthesis or orthosis, which mimics or assists a non-functioning or impaired muscle. In another embodiment of the invention, the positive power comes from an on-board power source in the prosthesis or orthosis.

Claims

1. An autonomous motorized powered-catapult device having a mounted end adapted to be attached to a wearer'"'"'s residual limb and an opposite distal end, said device comprising:

a leg prosthesis having an ankle joint;

an electromechanical actuator adapted to power the leg prosthesis, comprising;

an elastic element configured to store elastic energy, and

a motor operatively coupled to the elastic element;

a sensor for sensing gait information; and

a control system configured to cause the motor to store additional elastic energy in the elastic element as a function of information from the sensor for later release of stored energy from the elastic element to cause ankle powered plantar-flexion of the leg prosthesis thereby providing net positive mechanical work.

2. The device of claim 1, further comprising a clutch adapted to be actuated when the elastic energy is stored in the elastic element and adapted to allow release of the stored energy.

3. The device of claim 2, wherein the control system is configured to cause actuation and release of the clutch.

4. The device of claim 2, wherein the clutch is separate from the actuator.

5. The device of claim 1, wherein the control system is configured to cause the motor to store additional elastic energy in the elastic element and to release the stored energy from the elastic element during a gait cycle.

6. The device of claim 5, wherein the control system is configured to cause the motor to store additional elastic energy in the elastic element at the same time as a natural leg attached to the leg prosthesis stores energy during the gait cycle.

7. The device of claim 1, wherein the control system is configured to cause the motor to store additional elastic energy in the elastic element at the same time that the elastic element stores energy during a gait.

8. The device of claim 1, wherein the elastic element comprises a spring.

9. The device of claim 1, wherein an amount of energy stored in the elastic element by a natural leg attached to the leg prosthesis from compression is different than an amount of energy released from the elastic element to provide the ankle powered plantar-flexion of the leg prosthesis.

10. The device of claim 9, wherein the amount of energy stored in the elastic element by the natural leg attached to the leg prosthesis from compression is less than the amount of energy released from the elastic element to provide the ankle powered plantar-flexion of the leg prosthesis.

11. The device of claim 1, wherein the elastic element comprises a tension band.

12. The device of claim 1, wherein the sensed gait information comprises at least one of joint position, angular velocity and a phase of gait.

13. The device of claim 1, wherein the sensed gait information comprises at least one of angular displacement, linear displacement and force.

14. The device of claim 1, wherein the control system is configured to cause the motor to store additional elastic energy in the elastic element during a swing phase of gait.

15. The device of claim 1, wherein the control system is configured to cause the motor to store additional elastic energy in the elastic element during a minimal-load portion of gait.

16. The device of claim 1, wherein the elastic element comprises at least one end coupled to the motor.

17. The device of claim 1, wherein the elastic element is disposed in parallel with the motor.

18. The device of claim 1, wherein the elastic element couples the mounted end to the distal end.

19. The device of claim 1, wherein the control system is configured to cause the motor to operate in response to at least one of walking speed and ground irregularities.

20. The device of claim 1, wherein the actuator comprises a controllable mechanical impedance.

21. The device of claim 20, wherein the impedance of the actuator is controllable as a function of at least one of joint position, angular velocity and phase of gait.

22. The device of claim 1, wherein the actuator is configured to increase positive mechanical work or stiffness of the leg prosthesis as a function of at least one of locomotory speed and ground irregularities.

23. The device of claim 1, wherein the actuator is configured to increase peak mechanical power output of the leg prosthesis as a function of at least one of joint position, angular velocity and phase of gait.

24. The device of claim 1, wherein the sensor is a force sensor.

25. The device of claim 1, wherein the sensor is a displacement sensor.