Continuous–Discrete Time-Observer Design for State and Disturbance Estimation of Electro-Hydraulic Actuator Systems

In this paper, a continuous-discrete time observer which simultaneously estimates the unmeasurable states and the uncertainties for the electro-hydraulic actuator (EHA) system is presented. The main feature of the proposed observer is the use of an intersample output predictor which allows the users to increase the frequency acquisition of the piston position sensor without affecting the convergence performance. The stability analysis of the proposed observer is proved using Lyapunov function adapted to hybrid systems. To show the efficiency of our proposed observer, numerical simulations and experimental validation involving a control application, which combines the designed observer and a proportional-integral (PI) controller for the purpose of piston position tracking problem, are presented.