DISTURBANCE OBSERVER BASED POSITION CONTROL OF A ONE-LINK MANIPULATOR UNDER INPUT TIME DELAY

Abstract

To improve the robust performance against input time delay and time-varying disturbances, a non-minimum phase disturbance observer (DOB) approach is investigated for the position control of a one-link manipulator driven by a direct-current (DC) motor with a harmonic drive gear. The time-delay control problem for a system with an integrator is especially difficult when the disturbance input is a time-varying signal. The effect of the time-varying disturbance owing to the load mass uncertainty has been alleviated using a non-minimum phase DOB together with a Smith predictor (SP). In order to test the performance of the proposed controller, comparative computer simulations and experiments have been carried out with the manipulator system. In the simulations, we have considered the uncertainties for the delay time as well as the load mass of the system. The experimental results confirm the robust performance of the proposed method against system uncertainties. © 2012 ICIC International.