Powered artificial knee with agonist-antagonist actuation

• US 9,149,370 B2
• Filed: 08/05/2013
• Issued: 10/06/2015
• 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., Martinez-Villalpando, Ernesto C., Weber, Jeff Anthony
• Primary Examiner(s): WATKINS, MARCIA LYNN
• Application Number:
  US13/959,495
• Publication Number:
  US 20140046455A1
• Time in Patent Office: 792 Days
• Field of Search: 623/24, 623/27, 623/39, 623/43, 623/44, 623/45, 623/46, 602/16, 602/23, 602/26, 601/33, 601/34
• US Class Current: 1/1
• CPC Class Codes: A61F 2/64 Knee joints
• CPC Class Codes: A61F 2/6607 Ankle joints
• CPC Class Codes: A61F 2/70 electrical
• CPC Class Codes: A61F 2/72 Bioelectric control, e.g. myoelectric
• CPC Class Codes: A61F 2/741 using powered actuators, e.g. stepper motors or solenoids
• CPC Class Codes: A61F 2002/5003 having damping means, e.g. shock absorbers
• CPC Class Codes: A61F 2002/5075 Multiple spring systems including two or more helical springs
• CPC Class Codes: A61F 2002/6657 having a plate-like or strip-like spring element, e.g. an energy-storing cantilever spring keel
• 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 2002/763 for measuring spatial position, e.g. global positioning system [GPS]
• 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: B62D 57/032 with alternately or sequentially lifted supporting base and legs; with alternately or sequentially lifted feet or skid B62D57/024 takes precedence

Abstract

A knee prosthesis comprises an agonist-antagonist arrangement of two series-elastic actuators in parallel, including a knee joint, flexion and extension actuators connected to the joint in parallel with a leg member, and a controller for independently energizing the actuators to control the movement of the knee joint and leg. The flexion actuator comprises the series combination of a flexion motor and a flexion elastic element and the extension actuator comprises the series combination of an extension motor and an extension elastic element. Sensors provide feedback to the controller. The flexion actuator and the extension actuator may be unidirectional, with the flexion and extension elastic elements being series springs. The extension actuator may alternatively be bidirectional, with the extension elastic element being a set of pre-compressed series springs. Alternatively, the flexion elastic element may be a non-linear softening spring and the extension elastic element may be a non-linear hardening spring.

Claims

1. An artificial knee component, comprising:

a) a mechanical knee joint;

b) a first rotary actuator;

c) a first linear ball screw connected to the first rotary actuator;

d) a link between the linear screw and the mechanical knee joint, the link including a first ball-nut threadably engaged with the first linear screw, whereby actuation of the first rotary actuator rotates the first linear screw which, in turn, causes the link to move linearly along a major longitudinal axis of the first linear screw and rotate the mechanical knee joint, thereby converting linear force on the link by the first linear screw to torque about the mechanical knee joint;

e) a second rotary actuator; and

f) a second linear screw connected to the second rotary actuator, whereby the second rotary actuator rotates the second linear screw which, in turn, causes linear movement of the link along a major longitudinal axis of the second linear screw and rotation of the mechanical knee joint in a direction opposite that of the first rotary actuator, thereby converting linear force of the second linear screw to torque about the mechanical knee joint.

2. The artificial knee component of claim 1, wherein the link further includes a loop that extends between the first ball-nut and the mechanical knee joint, whereby linear movement of the first ball-nut along the first linear screw consequent to rotation of the first linear screw causes travel of the loop about the knee joint, thereby converting linear force on the first ball-nut by the first linear screw to torque about the mechanical knee joint.

3. The artificial knee component of claim 2, further including a first spring between the first ball-nut and the loop, thereby damping relative movement between the first ball-nut and the loop.

4. The artificial knee component of claim 3, further including a carriage that is attached to the loop and interposed between the first spring and the loop, whereby linear movement of the carriage parallel to the major longitudinal axis of the first linear screw causes travel of the loop about the knee joint, thereby converting linear force on the carriage by the first ball-nut on the first spring and carriage to torque about the knee joint.

5. The artificial knee component of claim 4, further including a first joint pulley that rotates about the knee joint, wherein the loop is mounted on the pulley.

6. The artificial knee component of claim 5, wherein the loop includes a flexible driving element.

7. The artificial knee component of claim 6, wherein the flexible driving element includes a cable.

8. The artificial knee component of claim 7, further including a second joint pulley located remotely from the first joint pulley at an end of the first linear screw opposite that of the first joint pulley, and on which the loop is also mounted, thereby causing the linear movement of the carriage parallel to the major longitudinal axis of the first linear screw to result in travel of the loop about the first and second joint pulleys.

9. The artificial knee component of claim 8, wherein the artificial knee joint is a prosthetic knee joint.

10. The artificial knee component of claim 8, further including a second spring on a side of the carriage opposite that of the first spring, the carriage also being interposed between the second spring and the loop.

11. The artificial knee component of claim 10, wherein the first and second springs are aligned with the major longitudinal axis of the first linear screw.

12. The artificial knee component of claim 11, wherein the first and second actuators operate in an agonist-antagonist relation to each other.

13. The artificial knee component of claim 12, further including a second ball-nut threadably engaged with the second linear screw.

14. The artificial knee component of claim 13, wherein the second spring is between the second ball-nut and the loop, thereby damping relative movement between the second ball-nut and the loop.

15. The artificial knee component of claim 11, wherein the first and second actuators are uni-directional actuators.

16. The artificial knee component of claim 11, wherein the first actuator is a bi-directional actuator and the second actuator is a uni-directional actuator.

17. The artificial knee component of claim 16 wherein the second linear screw is a lead screw.

18. The artificial knee component of claim 11, wherein the first and second actuators are rotary motors.

19. The artificial knee component of claim 1, wherein the first and second actuators operate in an agonist-antagonist relation to each other.