Mechanical Properties Of Piezoelectric Ceramics Modeling And Control Research

The actuator which is made up of piezoelectric ceramics and other intelligent materials has many advantages,a high displacement resolution,small size,fast response and so on,being able to transform the input drive voltage into nano-precision movement swiftly,is widely used in electronics,optics,mechanical manufacturing and aerospace and other technical fields,however,the piezoelectric ceramic's inherent hysteresis,creep and other mechanical properties lead to the non-linearity of piezoelectric ceramic displacement output,which brings great difficulty to the precise control of piezoelectric ceramic displacement,the hysteresis nonlinearity has the most prominent effect on the system accuracy.So the research of taking piezoelectric ceramic actuator as the precise positioning has been highly concerned about by domestic and foreign scholars.Aiming at the above problems,this paper studies deeply the piezoelectric ceramics' hysteresis and creep nonlinearity by combining the modeling and control methods of mechanical properties of piezoelectric ceramics domestic and abroad,the inverse model of displacement and hysteresis is obtained,and design the corresponding controller by controlling the input voltage to improve the system positioning accuracy.In this paper,the driving mechanism of stack-type piezoelectric ceramics is analyzed theoretically and set up a dual-frequency laser interference nanometer measurement system.The hysteresis and creep characteristics were tested by experiment,and the basic characteristics and laws of hysteresis and creep were obtained.Based on the experimental data,the polynomial model is established to describe the hysteresis inverse state by using the least squares method,thus extending the input space to establish neural network inverse model on hysteresis of the piezoelectric ceramic.The identification error is 0.66%.Based on the hysteresis inverse model,the control program of piezoelectric ceramic hysteresis compensation is designed,and the experiment of feed forwardopen loop control and feed-forward combined with PID control for linear compensation of hysteresis displacement is completed.The experimental results show that the hysteresis is reduced obviously.Based on the feed-forward open-loop control of polynomial inverse model,the experiment of displacement step reset of piezoelectric ceramic is completed,which reduces the start-stop displacement difference of piezoelectric ceramics by 92.37%.Given the expected displacement,the feed-forward open-loop control and feed-forward combined with the PID compound control algorithm is taken to do the displacement tracking experiment,the displacement tracking error is reduced to 1.84%.Finally,the characteristics and laws of creep of piezoelectric ceramics are analyzed.Combined with the conclusion of hysteresis control experiment,the method to reduce creep of piezoelectric ceramics is obtained,and the accuracy of micro/nano positioning is improved.