Sliding Mode Controller and Filter Applied to an Electrohydraulic Actuator System

摘要

A common problem pertaining to linear or nonlinear systems isnthe design of a combined robust control and estimation strategynthat can effectively deal with noise and uncertainties. The variablenstructure control (VSC) and its special form of sliding mode controln(SMC) demonstrate robustness with regard to uncertainties,nalthough their performance can be severely degraded by noise. Asnsuch they can benefit from using state estimates obtained fromnfilters. In this regard, this paper considers the use of a recentlynproposed robust state and parameter estimation strategy referrednto as the variable structure filter (VSF) in conjunction with SMC.nThe contribution of this paper is a new strategy that combinesnsliding mode control with the variable structure filter. In the presencenof bounded parametric uncertainties and noise, this combinednmethod demonstrates robust stability both in terms of controlnand state estimation. Furthermore, the combined strategy cannbe used to achieve high regulation rates or short settling time. Thencombined VSF and SMC strategy is demonstrated by its applicationnto a high precision hydrostatic system, referred to as thenelectrohydraulic actuator system.