Abstract
This paper deals with online parameter estimation of an electrohydraulic servo (EHS) system and with robust control of the EHS system utilizing the parameter estimated online. In this study, the natural frequency of the EHS system is estimated using pressure sensors based on the equation of motion and equation of continuity, and the estimate of the natural frequency is utilized to enhance the robustness of the EHS system combined with a parallel feed-forward compensator (PFC). The optimal value of one of the PFC parameters is strongly influenced by the natural frequency of the EHS system and is adaptively varied using the estimate of the natural frequency. It is shown that the natural frequency of the EHS system can be estimated relatively accurately using the method proposed, and that the robustness of the EHS system to the plant parameter variations can be enhanced by adapting the PFC parameter.
