HUMAN-ROBOT INTERACTIVE SYSTEM HAVING A HUMAN STIFFNESS ESTIMATION CONTROL ALGORITHM

• US 20110130876A1
• Filed: 11/30/2009
• Published: 06/02/2011
• Est. Priority Date: 11/30/2009
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: Menassa, Roland J., Stevenson, Robin, Gao, Dalong
• Granted Patent: US 8,483,879 B2
• Time in Patent Office: Days
• US Class Current: 700/258
• CPC Class Codes: B25J 9/1633 compliant, force, torque control, e.g. combined with position control
• CPC Class Codes: G05B 19/423 Teaching successive positions by walk-through, i.e. the tool head or end effector being grasped and guided directly, with or without servo-assistance, to follow a path
• CPC Class Codes: G05B 2219/36429 Power assisted positioning
• CPC Class Codes: G05B 2219/36435 Electromyographical, myoelectric control signal
• CPC Class Codes: G05B 2219/39338 Impedance control, also mechanical

Abstract

A robotic system includes a robot adapted for moving a payload in proportional response to an input force from an operator, sensors adapted for measuring a predetermined set of operator input values, including the input force, and a controller. The controller determines a changing stiffness value of the operator using set of operator input values, and automatically adjusts a level of control sensitivity over the robot using the stiffness value. The input values include the input force, a muscle activation level of the operator, and a position of the operator. A method of controlling the robot includes measuring the operator input values using the plurality of sensors, processing the input values using the controller to thereby calculate the stiffness value, and automatically adjusting the level of control sensitivity over the robot using the stiffness value. A specific operator may be identified, with control sensitivity being adjusted based on the identity.

Claims

1. A robotic system comprising:

a robot incorporating powered elements, the robot being adapted for moving a payload using the powered elements during an operation in proportional response to an input force from a human operator;

an operator-robot interface incorporating a plurality of sensors adapted for measuring a predetermined set of operator input values, including the input force; and

a controller that is responsive to the input force and adapted for actuating the powered elements, the controller being operable for determining a changing stiffness value of the human operator during the operation using the set of operator input values;

wherein the controller automatically adjusts a level of control sensitivity over the robot using the changing stiffness value to thereby optimize control stability.

2. The robotic system of claim 1, wherein the predetermined set of operator input values includes the input force and a muscle activation level of the operator, wherein the plurality of sensors includes at least one sensor adapted for measuring each of the input force and the muscle activation level.

3. The robotic system of claim 2, wherein the predetermined set of operator input values further includes a position of the operator, and wherein the plurality of sensors includes at least one sensor adapted for measuring the position of the operator.

4. The robotic system of claim 2, wherein the at least one sensor adapted for measuring the muscle activation level of the operator includes at least one of:

an electrode for directly measuring the muscle activation level, and a sensor for indirectly measuring the muscle activation level by at least one of measuring a change in a size of at least one muscle of the operator and measuring a grasping force of the operator.

5. The robotic system of claim 2, wherein the at least one sensor adapted for measuring the position of the operator includes one of a light source and a pressure mat.

6. The robotic system of claim 1, wherein the controller is adapted for identifying a specific operator from a plurality of different operators, and for selecting the level of control sensitivity based on the identity of the operator.

7. The robotic system of claim 1, wherein the controller automatically increases the level of control sensitivity when the stiffness value decreases or when the stiffness value is less than a calibrated threshold value, and automatically decreases the level of control sensitivity when the stiffness value increases or when the stiffness value exceeds the calibrated threshold value.

8. The robotic system of claim 1, wherein the robot is configured as an overhead lift assistance mechanism including at least a motor and a brake.

9. A control system for providing motion control of a robot with optimized control stability, the robot having powered elements adapted for moving a payload in proportional response to an input force from a human operator, the control system comprising:

an operator-robot interface having a plurality of sensors adapted for measuring a predetermined set of operator input values, including the input force; and

a host machine having an algorithm adapted for determining a changing stiffness value of the human operator using the set of operator input values;

wherein the control system actuates the powered elements in response to the input force, and automatically adjusts a level of control sensitivity over the robot using the changing stiffness value to thereby provide the optimized control stability.

10. The control system of claim 9, wherein the predetermined set of operator input values includes the input force and at least one of:

a position of the operator, and a muscle activation level of the operator, wherein the plurality of sensors includes at least one sensor adapted for measuring the input force, and at least one sensor adapted for measuring a corresponding one of the position and the muscle activation level.

11. The control system of claim 9, wherein the at least one sensor adapted for measuring the position of the operator includes one of a light source and a pressure mat.

12. The control system of claim 9, wherein the control system is adapted for identifying a specific operator from a plurality of different operators, and for selecting the level of control sensitivity based on the identity of the operator.

13. The control system of claim 9, wherein the controller automatically increases the level of control sensitivity when the stiffness value is less than a calibrated threshold value, and decreases the level of control sensitivity when the stiffness value exceeds the calibrated threshold value.

14. A method of controlling a robot incorporating powered elements that are collectively adapted for moving a payload in proportional response to an input force from a human operator, the method comprising:

measuring a predetermined set of operator input values, including the input force, using a plurality of sensors of an operator-robot interface;

processing the set of operator input values using a controller to thereby calculate a changing stiffness value of the human operator;

controlling the powered elements in response to the input force; and

automatically adjusting a level of control sensitivity over the robot using the changing stiffness value, thereby optimizing control stability.

15. The method of claim 14, including a strap adapted for measuring a muscle activation level of the operator, wherein measuring a predetermined set of operator input values measuring the muscle activation level via the strap.

16. The method of claim 14, including a handle adapted for measuring a muscle activation level of the operator by evaluating a grasping force of the operator, wherein measuring a predetermined set of operator input values measuring the muscle activation level via the handle.

17. The method of claim 14, further comprising:

identifying a specific operator from a plurality of different operators, and then selecting the level of control sensitivity based on the identity of the operator.

18. The method of claim 14, further comprising:

comparing the stiffness value to a calibrated threshold value, automatically increasing the level of control sensitivity when the stiffness value is less than the calibrated threshold value, and decreasing the level of control sensitivity when the stiffness value exceeds the calibrated threshold value.