Constrained Resolved Acceleration Control

• US 20130013112A1
• Filed: 02/17/2011
• Published: 01/10/2013
• Est. Priority Date: 02/25/2010
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Darish, Behzad
• Granted Patent: US 9,205,887 B2
• Time in Patent Office: Days
• US Class Current: 700/259
• CPC Class Codes: B25J 9/1697 Vision controlled systems
• 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 system, method, and computer program product for controlling an articulated system are described. The system estimates kinematics of body segments of the articulated system and constructs a weighted pseudo-inverse matrix to enforce kinematic constraints as well as achieve dynamic consistency based on the estimated kinematics. The system converts task descriptors to joint commands using the weighted pseudo-inverse matrix and controls the articulated system at both the velocity level and the acceleration level and enforces kinematic constraints using the joint commands.

Claims

1. A computer-implemented method for controlling an articulated system, the method comprising:

receiving a task descriptor specifying a movement of a body segment of the articulated system;

estimating kinematics of the body segment of the articulated system;

constructing a weighted matrix based on the estimated kinematics of the body segment;

generating a joint command for a joint associated with the body segment based on the weighted matrix, wherein the joint command controls an acceleration of the body segment and enforces one or more kinematic constraints of the articulated system; and

controlling the joint associated with the body segment using the joint command.

2. The method of claim 1, wherein the weighted matrix comprises a weighted pseudo-inverse matrix constructed as a superposition of a plurality of weighted matrices, one of the plurality of weighted matrices is constructed to control a velocity of the body segment.

3. The method of claim 2, wherein one of the plurality of weighted matrices is constructed to penalize a joint in the articulated system with a movement directing a body segment of the articulated system towards a kinematic constraint.

4. The method of claim 2, wherein one of the plurality of weighted matrices is constructed to minimize the instantaneous kinetic energy of the articulated system.

5. The method of claim 1, wherein one of the plurality of weighted matrices sets an acceleration of the joint associated with the body segment to zero responsive to the acceleration contributing to a violation of a kinematic constraint.

6. The method of claim 1, wherein the articulated system comprises a legged humanoid robot, the method further comprising:

generating a high-priority task for enforcing foot contact constraints for feet of the legged humanoid robot.

7. The method of claim 1, wherein generating the joint command further comprises:

generating the joint command for the joint associated with the body segment based on the weighted matrix and a joint velocity feedback term designed to provide stability for a resulting movement of the articulated system.

8. The method of claim 1, further comprising:

receiving an image stream comprising movements of a source system;

detecting body features of the source system in the image stream; and

generating the task descriptor based on the detected body features.

9. The method of claim 8, wherein the source system comprises a human, the articulated system comprises a humanoid robot, and the joint command controls the humanoid robot to simulate the human motion.

10. The method of claim 1, wherein the joint command is generated using a closed loop inverse kinematics (CLIK) algorithm.

11. A non-transitory computer-readable storage medium containing executable computer program code for performing a method for controlling an articulated system, the method comprising:

receiving a task descriptor specifying a movement of a body segment of the articulated system;

estimating kinematics of the body segment of the articulated system;

constructing a weighted matrix based on the estimated kinematics of the body segment;

generating a joint command for a joint associated with the body segment based on the weighted matrix, wherein the joint command controls an acceleration of the body segment and enforces one or more kinematic constraints of the articulated system; and

controlling the joint associated with the body segment using the joint command.

12. The storage medium of claim 11, wherein the weighted matrix comprises a weighted pseudo-inverse matrix constructed as a superposition of a plurality of weighted matrices, one of the plurality of weighted matrices is constructed to control a velocity of the body segment.

13. The storage medium of claim 12, wherein one of the plurality of weighted matrices is constructed to penalize a joint in the articulated system with a movement directing a body segment of the articulated system towards a kinematic constraint.

14. The storage medium of claim 12, wherein one of the plurality of weighted matrices is constructed to minimize the instantaneous kinetic energy of the articulated system.

15. The storage medium of claim 11, wherein one of the plurality of weighted matrices sets an acceleration of the joint associated with the body segment to zero responsive to the acceleration contributing to a violation of a kinematic constraint.

16. A system for controlling an articulated system, the system comprising:

a computer processor for executing executable computer program code;

a computer-readable storage medium containing the executable computer program code for performing a method comprising;

receiving a task descriptor specifying a movement of a body segment of the articulated system;

estimating kinematics of the body segment of the articulated system;

constructing a weighted matrix based on the estimated kinematics of the body segment;

generating a joint command for a joint associated with the body segment based on the weighted matrix, wherein the joint command controls an acceleration of the body segment and enforces one or more kinematic constraints of the articulated system; and

controlling the joint associated with the body segment using the joint command.

17. The system of claim 16, wherein the weighted matrix comprises a weighted pseudo-inverse matrix constructed as a superposition of a plurality of weighted matrices, one of the plurality of weighted matrices is constructed to control a velocity of the body segment.

18. The system of claim 17, wherein one of the plurality of weighted matrices is constructed to penalize a joint in the articulated system with a movement directing a body segment of the articulated system towards a kinematic constraint.

19. The system of claim 17, wherein one of the plurality of weighted matrices is constructed to minimize the instantaneous kinetic energy of the articulated system.

20. The system of claim 16, wherein one of the plurality of weighted matrices sets an acceleration of the joint associated with the body segment to zero responsive to the acceleration contributing to a violation of a kinematic constraint.