2-SMC of Electro-Hydraulic Drives Using the Twisting Algorithm

In this paper a controller utilizing second order sliding modes, generally applicable for position tracking control of electro-hydraulic valve-cylinder drives (VCD), is proposed. The proposed controller requires pressure measurements, and only the signs of the valve spool position and piston position- and velocity. The main objective is to introduce a control concept that provide for increased performance compared to linear controllers, in the presence of the inherent nonlinear nature characterizing such systems. To accomplish this task, a controller based on the twisting algorithm and knowledge of system gain variations is proposed. Results demonstrate strong robustness when subjected to parameter perturbations and that control chattering is eliminated.