SLIDING-MODE CONTROL OF MULTILINK FLEXIBLE MANIPULATORS

Abstract

This paper is a continuation of the research efforts reported recently in Yeung and Chen (1989) and Yeung and Chen (1991). This present work presents an extension of the sliding-mode control design method to multi-link flexible manipulators. There are two main steps in the design procedure, linearization and stabilization. In the linearization step, the sliding-mode technique is used to replace the rigid part of the dynamic equations by a set of linear equations which are determined by the switching surfaces. In the stabilization step, conventional PD/PID compensations are adopted to stabilize the linearized time-invariant system in the following three cases: (1) first-link ramp-tracking of the manipulator on a horizontal plane, (2) first-link parabola-tracking of the manipulator on a horizontal plane, and (3) first link regulation of the manipulator in a vertical plane. The developed sliding-mode controller is simple and requires no inertia matrix inversion, no modal estimation and no payload forecast. Simulation studies have been conducted to demonstrate the robustness of the controller against both input disturbances and payload variations.