Abstract: Aiming at the problem of loading accuracy and response speed of passive electro-hydraulic load simulator, non-linear factors which including non-linear friction and chamber-s effect of the actuator and the disturbance of position system in electro-hydraulic load simulator were studied. For non-linear factors, a system nonlinear mathematical model including smooth friction model and chamber-s effect of the actuator were established. For the disturbance of position system, based on Lyapunov stability theory the selection of gain in the sliding surface s was discussed. Then a variable gain sliding mode controller with smooth output was designed by employing the double power reaching law. The numerical simulation of the system was carried out by using Matlab/Simulink. The results indicate that the loading accuracy, response speed and the robustness of the load simulator are improved by the variable gain sliding mode controller. The overshoot of system output is not more than 5%, and the maximum static and dynamic errors are not more than 5%.
Key words: electro-hydraulic load simulator; double power reaching law; sliding mode control; lyapunov function; chambe-s effect