Disturbance observer‐based output feedback control of hydraulic servo system considering mismatched uncertainties and internal pressure dynamics stability

Abstract

For valve-controlled hydraulic servo system, the suppression of mechanical dynamics uncertainties and the analysis of internal pressure dynamics stability (i.e. the pressure into the two chambers of the actuator) are still the widespread concern issues. This study presents an easy-to-implement observer-based output feedback control scheme for hydraulic valve-controlled single-rod actuator system with addressing mismatched mechanical dynamic uncertainties and proving internal pressure dynamics stability analysis. The singular value perturbation approach is used to simplify the system model, and then a practical output feedback controller augmented with extended-state observer is developed through back-stepping design approach. The main contribution of this study is two-fold. First, a practical reduced-order model-based back-stepping controller is developed. Second, the stability issue of internal pressure dynamics is analysed. Besides giving theoretical analysis, extensive comparative co-simulations and experiments are carried out to illustrate the effectiveness of the proposed method. The present method can guarantee prescribed tracking transient performance in the presence of uncertain disturbances. Also, the stability of internal dynamics is proved.