Bang-Bang Control of Electrohydraulic Servomechanisms

Abstract

The optimum control is given for an electro-hydraulic servomechanism. It is approximated by two quasi-optimum controls which are reasonable in point of the control sensitivity and the practical construction of control system. The optimum control is obtained by the bang-bang control except in a very special case. The optimum switching points are determined as intersections of the phase trajectories and the switching surface in the phase space. We determine the switching points by the projections on the phase plane. The switching based on the fixed mathematical model is not favorable for considering the sensitivities to parameter variations. Two quasi-optimum controls are considered. One is obtained by approximating the optimum switching curve by two lines on the phase plane, the other by approximating the switching surface by a switching plane in the phase space. The errors due to the approximations are investigated. The satisfactory results are obtained in experiments and the advantages of this method are verified.