Abstract: A design method of adaptive sliding mode control law based on the equivalent control is presented aiming at the tracking control problem of electrohydraulic servo force control systems with uncertainties and nonlinearities．To eliminate the influence of uncertainties on the control performance a parameter adaptive method is used．Consequently the goal of robust tracking control is obtained．To illustrate the feasibility of this controller，it is implemented using a microcomputer on an electrohydraulic servo system of fatigue testing machine．The results of the real-time control verify the validity of the proposed adaptive sliding mode control method．

Key words: Robust tracking control, Electrohydraulic servo force control systems Adaptive sliding mode control