Piezoelectric Hydroelectric Servo Valve And Its Control Method

This work is supported by the National High Technology Research and Development Program of China (863 Program) under Grant 2001AA423270. The paper develop a new type of piezoelectric hydroelectric servo valve and analysis its characteristic. The paper studies control method of the piezoelectric hydroelectric servo valve because of its nonlinear. Hydraulic servo control is burgeoning technology. Hydroelectric servo system is widely applied on industry domain nowadays, such as industry process, military aeromechanics and so on. The paper designs a new type of transducer-bimorph actuator act as electric-mechanic transducer of nozzle flapper hydroelectric servo valve and analysis static and dynamic characteristic. Experiment results show that bimorph actuator has better linear repeatability between voltage and displacement and has bigger displacement and better dynamic characteristic. Herby, bimorph actuator is suit to act as pre-stage amplifier of nozzle flapper hydroelectric servo valve. The static and dynamic characteristic of multi-layer piezoelectric actuator is analyzed. Static characteristic experiment results show that multi-layer piezoelectric has hysteresis and creep nonlinear. Static characteristic experiment results that multi-layer piezoelectric has better dynamic characteristic. Hereby, multi-layer c is suit to act as pre-stage amplifier of direct drive servo salve.The paper develop nozzle flapper two-stages bimorph hydroelectric servo valve and direct drive two-stages piezoelectric hydroelectric servo valve and direct drive one-stage piezoelectric hydroelectric servo valve. Design experiment system of hydroelectric servo valve and study on static and dynamic characteristic of three new type piezoelectric hydroelectric servo valves. Experiment results show that nozzle flapper two-stages bimorph hydroelectric servo valve and direct drive two-stages piezoelectric hydroelectric servo valve have relay-saturation characteristic, direct drive one-stage piezoelectric hydroelectric servo valve has hysteresis nonlinear. Nonlinear debase precision and stability of control system, influence control quality. Hereby, for the sake of improve object's static and dynamic characteristic, demand to study effective control method. First, the paper study control method of nozzle flapper two-stages bimorph hydroelectric servo valve and direct drive two-stages piezoelectric hydroelectric servo valve. Because nozzle flapper two-stages bimorph hydroelectric servo valve and direct drive two-stages piezoelectric hydroelectric servo valve system have relay- saturation characteristic, open loop control is difficult to arrive to set point and must adopt close loop control method. The movement of the two-stage direct drive piezoelectric servo valve is restricted by the linear range of execution mechanism, when the conventional PID control arithmetic is adopted, the system will have a large overshoot, which will affect the stability of the system seriously. Furthermore, the experiments show that the system has complicated nonlinearity. That is, when the parameters that have good control characteristic in one work space is used in another work space, the characteristic of the control system will decrease. Besides, the control parameters are also related to the movement direction. That is, the parameters that have good control characteristic in the positive direction cannot be used in the reverse direction very well. Hence, a bidirection piecewise gearshift integral PID control method is proposed in this paper. The whole movement range of the slide valve is separated into 2×N small regions based on the movement direction and the movement position of the slide valve. In each region, the gearshift integral PID parameters are adjusted. Experiment results have confirmed the effectiveness of the proposed method.Second, the paper study control method of direct drive one-stage piezoelectric hydroelectric servo valve.Experiment results show that direct drive one-stage piezoelectric hydroelectric servo valve exist hysteresis...