| Electro-hydraulic servo valve is the core component of the electro-hydraulic servo system,an electro-hydraulic servo system with excellent quality,depends on the electro-hydraulic servo valve with high frequency response and high control precision performance.The pursuit of higher performance servo valve has been the research goal of scholars all over the world.Especially since entering the 21 st century,the demand for high-speed and precision control valves is increasing day by day in the fields of national defense,military and industrial control.However,the traditional electro-hydraulic servo valve mostly uses torque motor or force motor as the pre-stage driver.Due to the limitation of the structure and performance of the driver itself,its frequency response and control precision have entered the development bottleneck.In recent years,with the rapid development of new material technology,the piezoelectric actuators made of piezoelectric materials have been applied to the design of new electro-hydraulic servo valves because of their excellent dynamic performance,which has become an important research direction to achieve high frequency response servo valves.However,there is a huge difference between traditional electro-hydraulic servo valve and piezoelectric servo valve in control.In order to study the influence of nonlinear characteristics such as capacitance effect and hysteresis creep on the performance of piezoelectric electro-hydraulic servo valve,and to improve the high frequency characteristics of piezoelectric servo valve,the characteristics and control methods of high frequency piezoelectric servo valve are studied in this paper.The research contents are as follows:1.A piezoelectric direct drive servo valve is designed by referring to relevant literature.Combined with piezoelectric theory and hydraulic servo control principle,the mathematical model and AMESim simulation model of the servo valve are established to analyze the static and dynamic characteristics of the servo valve and prove the high frequency characteristics of the piezoelectric servo valve.At the same time,the factors that may affect the dynamic characteristics of the piezoelectric servo valve are analyzed,and the frequency extension mechanism of the piezoelectric servo valve is studied.2.By introducing the generalized asymmetric Bouc-Wen model,the nonlinear dynamics model of the piezoelectric servo valve is built.Based on this optimization model,the nonlinear problems of the servo valve,such as the deterioration of dynamic performance and the reduction of control precision,caused by the hysteresis of the piezoelectric actuator are studied.At the same time,an asymmetric Bouc-Wen hysteresis model parameter identification method based on genetic algorithm was designed,and the inverse model feedforward compensation control of the piezoelectric servo valve was accomplished through the identified hysteresis model.3.The combined control of PID control,fuzzy PID control,sliding mode control and feedforward compensation is designed,and the control effects of these control methods are comprehensively compared through the co-simulation platform of AMESim and Simulink.4.The control platform of the piezoelectric servo valve is designed and built,and the feasibility of the control platform is verified through the experiment of the electro-hydraulic servo valve system,which lays the foundation for the further research of the piezoelectric servo valve.This paper relies on AMESim and Simulink co-simulation platform to complete the construction of the piezoelectric servo valve control system and hydraulic model,the effect is more perfect than the simple mathematical simulation,more in line with the actual situation.At the same time,the piezoelectric servo valve control strategy research and control platform construction can be used for the next design of piezoelectric servo valve and the hardware-in-the-loop control experiment. |
PDF Full Text Request