PWM-digital control of hydraulic actuator utilizing 2-way solenoid valves.

This study deals with a hydraulic actuator system which is operated by two 2-way solenoid valves in the PWM-Digital mode. The solenoid valves act as converters of electronic-pulse signals to hydraulic-ones.It is considered that the dynamic characteristics of the system depend largely on the be h avior of on/off action of the solenoid valves. The response performance of the system, for example, might be inevitably affected by the time lag existing between the input and output signals of the valves. Details of such effects of the solenoid valves, however, have yet to be satisfactorily clarified, mainly because an adequate mathematical model for the system has not been developed. The object of this study is, therefore, to prop o se a mathematical model for the PWM-actuator system. The dynamic charateristics of the system are investigated by the method of digital simulation based on the proposed model. The simulated time responses are compared with the measured ones to confirm the validity of the mathematical model.