Modeling and position sliding mode control of a hydraulic actuators using on/off valve with PWM technique

In addition to their high power capabilities, the hydraulic servo systems, have a high degree of accuracy and very rapid response, thus new needs in hydraulic systems are continuously emerging such as industrial manipulators, mechanisms and mechanical devices and other uses. To achieve high performance, the system requires precise control of position, velocity, acceleration and force in actuators. In this paper, the modeling and control of an actuator is done by two switching valves (3/2 way). Regarding some uncertainty, the sliding mode controller is used for actuator position control. So, the discrete time inputs, using averaging analysis, are converted to continuous, which are applied in sliding mode. The performance of the suggested method is simulated by step and sine inputs at different frequencies.