Modeling supply and return line dynamics for an electrohydraulic actuation system

This paper presents a model of an electrohydraulic fatigue testing system that emphasizes components upstream of the servovalve and actuator. Experiments showed that there are significant supply and return pressure fluctuations at the respective ports of the servovalve. The model presented allows prediction of these fluctuations in the time domain in a modular manner. An assessment of design changes was done to improve test system bandwidth by eliminating the pressure dynamics due to the flexibility and inertia in hydraulic hoses. The model offers a simpler alternative to direct numerical solutions of the governing equations and is particularly suited for control-oriented transmission line modeling in the time domain.