Development of a hydraulic manipulator servoactuator model: simulation and experimental validation

In this paper, modelling and identification of a hydraulic servoactuator system is presented. The importance of such a model is evident in further understanding the system and in order to develop a robust force controller. The model accounts for line losses, nonlinear orifice areas, hysteresis, friction, leakage, and load dynamics. System parameters are identified based on a high-performance hydraulic manipulator joint, and in particular, the elbow of the SARCOS slave manipulator. Specialized hardware was designed and constructed in order to help identify parameters, to allow line pressure measurements, and to validate the model. The model is verified by comparing simulation and experimental results in two modes: static and dynamic. The results prove to be very good. The developed model sheds light onto the subsystems in a hydraulic manipulator joint and will prove useful in the development of a robust force control algorithm.