Sliding Mode Control of Hydraulic Power Shovel.

Abstract

In this study, we deal with an excavator driven by three links-an arm, a boom, and a swing as a representative of construction robots. Here, each link consists of an electro-hydraulic servo system. A big problem with the use of such an excavator is the high degree of skill, and thus the comparatively long-term training regimen, that is necessary to operate it. In order to solve this problem, we equip the excavator with a trajectory control algorithm to control its front end. In this situation, it must be considered that the excavator's servo systems are influenced by disturbances and by many nonlinear characteristics, such as asymmetrical piston geometry, initial shifts in the neutral positions of the servo valves, and variations in the inertia of moving parts. As a method of trajectory control, in this study we apply in the servo systems a sliding mode control using a disturbance observer. The dynamic performance of this trajectory control system is investigated in experiments. The results of these experiments confirmed the validity of the applied method.