Abstract: The hydraulic servo control with generalized pulse code modulation is proposed, and the theory and method of realizing hydraulic servo control are researched by using on-off valves to substitute for servo valve or proportional valve, and the dynamic and static characteristics of the system are analyzed. To reduce the effect of force load on the control accuracy of the hydraulic position servo system, a load observers is designed. The equivalent load observed is fed back for resisting force load disturbance and raising the accuracy of the hydraulic position servo control.

Key words: Generalized pulse code modulation, Hydraulic servo control, Load observing, On-off valve