Direct Nonlinear Control for an Electro-hydraulic System

In this paper, an adaptive nonlinear controller is presented for position tracking control problem of a pump-controlled Electro Hydraulic System (EHS). The system nonlinearities are compensated by an advanced backstepping-based technique while all uncertainties including uncertain parameters and external disturbances are estimated directly from the state control errors. For supplying necessary information to the controller, mathematical model of the EHS is derived in which a view of certain, uncertain and nonlinear terms is clearly represented. The control input is then synthesized from candidate Lyapunov functions which are adopted to combine the adaptive law and the control algorithm. Finally, effectiveness of the proposed controller is evaluated through simulation results of different testing conditions.