Control of a heavy-duty robotic excavator using time delay control with integral sliding surface

The control of a robotic excavator is difficult from the standpoint of the following problems: parameter variations in mechanical structures, various nonlinearities in hydraulic actuators and disturbance due to the Contact with the ground. In addition, the more the size of robotic excavators increase, the more the length and mass of excavator's links, the more the parameters of a heavy-duty excavator vary. A time-delay control with switching action (TDCSA) using an integral sliding surface is proposed in this paper for the control of a 21-ton robotic excavator. Through analysis and experiments, we show that using an integral sliding surface for the switching action of TDCSA is better than using a PD-type sliding surface. The proposed controller is applied to straight-line motions of a 21-ton robotic excavator with a speed level at which skillful operators work, Experiments. which were designed for surfaces with various inclinations and over broad ranges of joint motions, show that the proposed controller exhibits good performance. (C) 2002 Elsevier Science Ltd. All rights reserved.