An elastoplastic friction compensator with improved static friction behavior

Abstract

Mahvash and Okamura's elastoplastic friction compensator is one of successful friction compensators for robotic joints with compliant transmissions. A limitation of the scheme is that, in the static friction state, the compensator continues commanding non-zero output force, which hampers the system's reaction to external forces. This paper presents an improved version of the elastoplastic friction compensator with an additional term, which makes the output force decay exponentially in the static friction state. The proposed method was validated using a linear actuator system with a ball screw and a timing belt. The experimental results show that the proposed method reduces external force required to move the device.