Modelling, identification and experimental validation of a hydraulic manipulator joint for control

In this paper, modelling and identification of a hydraulic servoactuator system is presented. The development of the model is important for further understanding the system and for developing a robust force controller. A systems approach is used to model the various subsystems including the servovalve dynamics, fluid dynamics and the vane and load dynamics. Included in the model are line losses, leakage, and hysteresis. System parameters are identified using the elbow joint of the SARCOS slave experimental hydraulic manipulator. Specialized hardware was designed and constructed for this purpose. The model was validated by comparing simulation and experimental results. The correlation between model and actual system response proved to be very good. Hence, the developed model predicts well the system dynamic behavior and will prove useful in the development of a robust force controller.