Nonlinear robust backstopping control of an electrohydraulic velocity servosystem

Electrohydraulic ServoSystem (EHSS) have been used in industry in a wide number of applications. Its dynamics are highly nonlinear and also have large extent of model uncertainties and external disturbances. So, it is necessary to use a robust nonlinear method to control the velocity of EHSS. This paper addresses the analysis and control of an electrohydraulic velocity servosystem in the presence of nonlinearities and unmodeled uncertainties or external disturbances. The proposed technique is based on robust backstepping method which we construct a robust control lyapunov function (rclf) and we will also provide a robustly stabilizing state feedback control law. This paper reports the designing details of controller and all derived results are validated by computer simulation of a nonlinear mathematical model of the system.