Robust Control of Mechanical Systems with Nonlinear Friction Considering Compliance of Transmission Mechanism

Abstract

Mechanical systems generally consist of three components; an actuator, load and power transmission mechanism such as a lead screw and gear coupling. Although there have been many researches on the controller design for mechanical systems with nonlinear friction, the compliance of the transmission mechanism has been little considered. Because the effect of nonlinear friction is significant when the transmission mechanism has low stiffness, its compliance should be considered in mechanical controller design for achieving the superior control performance. This paper presents a new approach to the controller design for mechanical systems with nonlinear friction considering the compliance of transmission mechanism. Because the effect of friction is generally unknown in advance, we design a robust controller based on the variable structure control that requires only the upper bound of friction magnitude. The effectiveness of proposed controller is demonstrated by comparative experimental results with a conventional state feedback controller.