Simulation analysis on friction compensation of a double tendon-sheath actuation system

Abstract

A tendon-sheath system has been researched for human-robot interaction systems because of its simple and light tendon routing mechanism. Since the tendons contact with the inner surface of sheaths in a tendon-sheath system, many undesirable phenomena appear due to the friction between them. Force transmission models and feedforward friction compensation methods have been developed for precise force transmission; however, those methods are not applicable with varying sheath curvatures. In this paper, a double-tendon sheath actuation system with a sheath routing method that enables feedforward torque control in a varying sheath curvatures is introduced. A feedforward friction compensation law was developed by analyzing the system, and was verified by a simulation.