Projected PID controller for Tendon-Driven Manipulators actuated by magneto-rheological clutches

Tendon-Driven Manipulators (TDM) have been used in various applications requiring low inertia robots having multiple degrees-of-freedom (DOF) and redundancy. TDMs are generally actuated by gear electric motors placed at the base of the robot, and consequently require complex cable tension feedback from force sensors or dynamic modelling to maintain cables under tension. This paper presents a high performance TDM actuated by magneto-rheological clutches along with a specialized motion control algorithm, termed Projected PID, that requires no tension feedback. A 2-DOF proof-of-concept TDM powered by magneto-rheological clutches is used to demonstrate overall controller performance, and a reconfigurable 2-DOF TDM powered by direct-drive electric motors is used to demonstrate the controller's ability to compensate for configuration variations and actuator failure. Experimental results also demonstrate the ability of Projected PID to control magneto-rheological cable-driven TDMs with high accuracy.