Improving Overshoot Performance of Discrete-time Sliding Mode Control with Decoupled Disturbance Compensator for Ramp-Type Disturbance

Abstract

This paper develops an overshoot enhancement method of discrete-time sliding mode control (DSMC) with a decoupled disturbance compensator (DDC) subject to ramp-type disturbances. The original DSMC with DDC method has several features such as excellent trajectory tracking, easy implementation, and robustness to disturbances. However, when the system suffers from ramp-type disturbance such as viscosity friction, position error remains and overshoot arises at the end of motion. They are highly undesirable in position control applications such as robot manipulators and manufacturing systems. In this paper, a new structure of DSMC with DDC is developed to reduce the overshoot. An outer loop is added to the original DSMC with DDC structure, which provides asymptotic convergence of the error state subject to ramp-type disturbance. A transfer function is derived to analyze the overshoot performance. Experiments are performed on an industrial linear motor system to demonstrate the improved overshoot performance.