Extended Sliding Mode Observer-Based Output Feedback Control for Motion Tracking of Electro-Hydrostatic Actuators

Abstract

This paper develops a novel output feedback control scheme for the motion-tracking problem of an electro-hydrostatic actuator (EHA) in the presence of model uncertainties and external disturbances. Firstly, a simplified third-order system model of the studied EHA is established using theoretical methods. For the first time, an extended sliding mode observer (ESMO) is introduced to simultaneously account for the shortage of unknown system states and modeling imperfections. Based on this, a robust nonlinear controller is developed using the backstepping control framework to stabilize the closed-loop system. This controller integrates estimates of immeasurable system states and lumped disturbances to deal with their adverse impacts. Moreover, the dynamic surface control (DSC) technique is employed to effectively mitigate the computational burden of the traditional backstepping framework. An ultimately uniformly bounded (UUB) performance is assured by using the recommended method. Furthermore, the stability of not only the observer but also the closed-loop system is concretely analyzed by using the Lyapunov theory. Finally, experiment results under various working scenarios are given to convincingly demonstrate the advantage of the suggested method in comparison with some reference control approaches.

Experimental Tests on the Influence of Accumulated Pressure Energy on the Response Time of a Hydraulic Cylinder under External Load Actuated in a Classic and Distributed System Structure

“…Their popularity results from the fact that in the classic architecture they have one central valve block which controls multiple receivers and is typically powered from one source. Research is currently performed into improving the operating characteristics by implementing a series of control solutions without manipulating the structure of the hydrostatic system [15][16][17][18][19][20]. Another, parallel research direction is to modify the classic structure of the system by adding a system which would allow the accumulation and reuse of the hydraulic energy, thus increasing the efficiency of the entire system [21,22].…”