System and method for tensioning a robotically actuated tendon

1. A tendon tensioning system comprising:

a tendon having a proximal end and a distal end;

an actuator coupled with the proximal end of the tendon and configured to apply a tension through the tendon in response to an electrical current, the actuator including a drive screw and a motor; and

a motor controller electrically coupled with the actuator, the motor controller configured to:

provide an electrical current having a first amplitude to the actuator until a stall tension is achieved through the tendon;

provide a pulse current to the actuator following the achievement of the stall tension, the amplitude of the pulse current being greater than the first amplitude; and

return the motor to a steady state holding current following the conclusion of the pulse current.

2. The system of claim 1 , wherein the distal end of the tendon is coupled with a finger of a dexterous robot.

3. The system of claim 1 , wherein the drive screw is a ball screw, the actuator further including a ball nut disposed about the ball screw and coupled with the tendon.

4. The system of claim 1 , wherein the motor controller is configured to allow the tension maintained in the tendon to dwell at the stall tension for a period of time before providing the pulse current to the actuator.

5. The system of claim 1 , wherein the holding current has an amplitude less than a maximum steady state current level of the system, and wherein the amplitude of the pulse current is less than a maximum instantaneous current level of the system.

6. The system of claim 1 , wherein the pulse current provided to the actuator is operative to increase the tension provided through the tendon to a boosted tension level, the boosted tension level being greater than the stall tension.

7. The system of claim 6 , wherein the actuator is configured to maintain the boosted tension level through the tendon following the conclusion of the pulse current.

8. The system of claim 1 , wherein the actuator configured to maintain at least a minimal tension on the tendon at all times during operation, the minimal tension being less than the stall tension.

9. A system for providing an increased grasping force through a finger of a dexterous robot during a grasping routine, the system comprising:

a tendon having a proximal end and a distal end and extending along a length of a finger of a dexterous robot, the distal end of the tendon being coupled to the finger;

a finger actuator including a drive screw and a motor and located in a lower arm assembly of the dexterous robot and apart from the finger, the finger actuator coupled with the proximal end of the tendon and configured to apply a tension through the tendon in response to an electrical current; and

a motor controller electrically coupled with the finger actuator, the motor controller configured to:

provide an electrical current having a first amplitude to the finger actuator until a stall tension is achieved through the tendon;

provide a pulse current to the actuator following the achievement of the stall tension, the amplitude of the pulse current being greater than the first amplitude; and

return the motor to a steady state holding current following the conclusion of the pulse current.

10. The system of claim 9 , wherein the drive screw is a ball screw, the actuator further including a ball nut disposed about the ball screw and coupled with the tendon.

11. The system of claim 9 , wherein the motor controller is configured to allow the tension maintained in the tendon to dwell at the stall tension for a period of time before providing the pulse current to the actuator.

12. The system of claim 9 , wherein the holding current has an amplitude less than a maximum steady state current level of the system, and wherein the amplitude of the pulse current is less than a maximum instantaneous current level of the system.

13. The system of claim 9 , wherein the pulse current provided to the actuator is operative to increase the tension provided through the tendon to a boosted tension level, the boosted tension level being greater than the stall tension.

14. The system of claim 13 , wherein the actuator is configured to maintain the boosted tension level through the tendon following the conclusion of the pulse current.

15. A method for controlling an actuator to tension a tendon, the method comprising:

providing a tendon having a proximal end and a distal end;

providing an actuator coupled with the proximal end of the tendon and configured to apply a tension through the tendon in response to an electrical current, the actuator including a drive screw and a motor;

driving the actuator with an electrical current having a first amplitude until a stall tension is achieved through the tendon;

delivering a pulse current to the actuator following the achievement of the stall tension, the amplitude of the pulse current being greater than the first amplitude; and

returning the electrical current delivered to the motor to a steady state holding amplitude following the conclusion of the pulse current.

16. The method of claim 15 , wherein the pulse current provided to the actuator is operative to increase the tension provided through the tendon to a boosted tension level, the boosted tension level being greater than the stall tension.

17. The method of claim 15 , further comprising:

providing a dexterous robot having a plurality of fingers; and

wherein the distal end of the tendon is coupled with a finger of a dexterous robot.

18. The method of claim 17 , wherein the dexterous robot includes forty two degrees of freedom.

19. The method of claim 17 , wherein the electrical current causes the actuator to apply a force to the finger.

20. The method of claim 15 , wherein the electrical current at the steady state holding amplitude discourages the motor from back driving.