On application of proportional valve-controlled hydraulic cylinder position servo system

Proportional valve-controlled hydraulic cylinder position servo system is a nonlinear, time-varying system which has a variable flow dead zone and flow gain. Using traditional control strategy is difficult to achieve satisfactory control effect. The self-regulating dynamic compensation method of dead zone has been raised to abate the hysteresis effect caused by the dead zone of electro-hydraulic proportional valve. At the same time, self-adapting fuzzy-PD control strategy has been put forward to solve the problem of variable flow gain. Finally, the track effects on sinusoidal signals were compared between self-adapting fuzzy-PD control system and PD control system through experiments in the case of different frequencies and loads. The results show that self-adapting fuzzy-PD controller can solve the contradictions between the speed and stability that the PD controller can´t do, while improving tracking precision by the use of self-regulating dynamic compensation method.