Exoskeleton controller for a human-exoskeleton system

• US 20060247904A1
• Filed: 03/30/2006
• Published: 11/02/2006
• Est. Priority Date: 06/29/2001
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Dariush, Behzad
• Granted Patent: US 7,774,177 B2
• Time in Patent Office: Days
• US Class Current: 703/11
• CPC Class Codes: B25J 9/0006 Exoskeletons, i.e. resembling a human figure
• 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

Techniques are provided for controlling an exoskeleton actuator at a joint of a human-exoskeleton system by receiving system parameters for the human-exoskeleton system, receiving generalized coordinates for the human-exoskeleton system, and determining an equivalent joint torque for the exoskeleton actuator to compensate for a selected force. While providing partial or complete compensation of selected gravitational and external forces, one embodiment of the present invention mitigates the amount of interference between voluntary control and assist control, thereby allowing humans to quickly humans adapt to an exoskeleton system.

Claims

1. A computer based method of controlling an exoskeleton actuator at a joint of a segment in a human-exoskeleton system, comprising:

receiving a system parameter for the human-exoskeleton system;

receiving a generalized coordinate for the human-exoskeleton system; and

determining an equivalent joint torque for the exoskeleton actuator at the joint to compensate for a selected force.

2. The method of claim 1, wherein determining the equivalent joint torque for the exoskeleton actuator at the joint to compensate for the selected force comprises:

selecting a force acting on the human-exoskeleton system for compensation; and

determining the equivalent joint torque for the exoskeleton actuator at the joint to compensate for the selected force.

3. The method of claim 1, wherein the selected force acts at one of:

a segment connected to the joint; and

a segment that is not connected to the joint.

4. The method of claim 1, wherein the selected force comprises one of:

a gravitational force; and

an external force.

5. The method of claim 4, wherein the external force comprises one of a reaction force, an applied force, an interaction force, a contact force, and a static load.

6. The method of claim 1, wherein determining the equivalent joint torque for the exoskeleton actuator at the joint to compensate for the selected force comprises determining the equivalent joint torque for the exoskeleton actuator at the joint to maintain static equilibrium.

7. The method of claim 1, wherein determining the equivalent joint torque for the exoskeleton actuator at the joint to compensate for the selected force comprises determining the equivalent joint torque for partial compensation of the selected force for one or more degrees of freedom.

8. The method of claim 1, further comprising:

obtaining a selection matrix comprising an element representing an assist ratio for partial compensation of a degree of freedom; and

determining an assist torque for partial compensation of the degree of freedom.

9. The method of claim 1, wherein the equivalent joint torque is determined recursively.

10. The method of claim 1, wherein determining the equivalent joint torque for the exoskeleton actuator at the joint to compensate for the selected force comprises recursively determining one or more joint moments at one or more successive joints until the joint is reached.

11. The method of claim 1, wherein the equivalent joint torque is determined from a dynamics equation of motion.

12. The method of claim 1, wherein the selected force is a gravitational force acting on the human-exoskeleton system, and wherein determining the equivalent joint torque to compensate for the gravitational force comprises determining a rate of change of potential energy of the human-exoskeleton system.

13. The method of claim 1, wherein the equivalent joint torque is determined using the principle of virtual work.

14. The method of claim 1, wherein determining the equivalent joint torque for the exoskeleton actuator at the joint to compensate for the selected force comprises constructing a Jacobian matrix to transform the selected force to the equivalent joint torque.

15. The method of claim 1, further comprising determining the feasibility of the method of controlling the exoskeleton actuator.

16. The method of claim 15, wherein determining the feasibility of the method of controlling the exoskeleton actuator comprises determining whether an instantaneous metabolic cost when the equivalent joint torque is applied to the exoskeleton actuator is less than the instantaneous metabolic cost without applying the equivalent joint torque to the exoskeleton actuator.

17. The method of claim 15, wherein determining the feasibility of the method of controlling the exoskeleton actuator comprises:

determining, for a positive net joint torque, whether the equivalent joint torque has a value greater than zero and less than twice the net joint torque; and

determining, for a negative net joint torque, whether the equivalent joint torque has a value less than zero and greater than twice the net joint torque.

18. The method of claim 15, wherein determining the feasibility of the method of controlling the exoskeleton actuator comprises determining whether the equivalent joint torque, when applied to the exoskeleton actuator, enhances or degrades stability of the human-exoskeleton system.

19. The method of claim 1, further comprising determining whether the method of controlling the exoskeleton actuator is mechanically efficient.

20. The method of claim 1, wherein the selected force is selected for compensation based on a feasibility criterion.

21. The method of claim 1, wherein the joint is an ankle joint and wherein the human-exoskeleton system comprises an ankle-foot orthosis.

22. A system for automatically controlling an exoskeleton actuator at a joint of a segment in a human-exoskeleton system, comprising:

first receiving means for receiving a system parameter for the human-exoskeleton system;

second receiving means for receiving a generalized coordinate for the human-exoskeleton system; and

first determining means for determining an equivalent joint torque for the exoskeleton actuator at the joint to compensate for a selected force.

23. The system of claim 22, wherein the first determining means for determining the equivalent joint torque includes second determining means for determining the equivalent joint torque for the exoskeleton actuator at the joint to maintain static equilibrium.

24. The system of claim 22, wherein the first determining means for determining the equivalent joint torque includes second determining means for determining the equivalent joint torque for partial compensation of the selected force for one or more degrees of freedom.

25. The system of claim 22, further comprising:

means for obtaining a selection matrix comprising an element representing an assist ratio for partial compensation of a degree of freedom; and

second determining means for determining an assist torque for partial compensation of the degree of freedom.

26. The system of claim 22, further comprising second determining means for determining the feasibility of the system for controlling the exoskeleton actuator.