Adaptive fuzzy—sliding mode control with fixed bias compensator for an electrohydraulic actuation system with hard nonlinearities

Abstract

An adaptive fuzzy sliding mode controller with fixed bias compensator is designed in this paper to address the issue of position control of an electrohydraulic actuation system. The adaptive fuzzy sliding mode controller approximately compensates for the system nonlinearities and minimizes the approximation errors. In order to attenuate the effects of discontinuous nonlinearities, the fixed bias compensator is introduced. The adaptation scheme is based on the Lyapunov function of the sliding function variable drawn up with Hurwitz coefficients, thereby ensuring the closed loop stability and convergence. Real time experiments conducted on an existing electrohydraulic laboratory set up comprising of a proportional valve and a single-rod cylinder evince that the proposed control method is robust for diverse range of demands.