Abstract:Aiming at piloted electrohydraulic proportional pressurereducing valve characteristics of uncertain parameters,immeasurable states and affected by load flow, an observer including load flow and it's feedback controller was designed, to achieve robust output feedback control to the output pressure. Based on linear matrix inequalities, theoretical analysis showed that the system was stable and had H∞robust performance. The method to obtain the observer gain L and controller gain K was given. By simulating a certain proportional pressure reducing valve, the validity of the algorithm was verified. The influence of load flow to output pressure was eliminated the output pressure following the set pressure quickly was ensured.