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.
Applied Mechanics and Materials, 2012, Vol 233, p. 131-134