Research On Micro/Nano Positioning Control System Based On Piezoelectric Ceramic Actuators

The rapid development of micro/nano positioning technology has greatly improved the level of research on the micro/nano areas.Micro/nano positioning technology is the basic link in the field of nano technology.Nano-scale positioning technology has stricter demand with the control algorithm,equipment and environment,compared with macro-scale positioning technology.Therefore,it is one of the hotspots in the field of micro/nano research to improve the motion positioning accuracy.Micro/nano positioning platform is an important tool for the study of micro-domain motion positioning technology.It is of great significance to study the control method to improve the positioning accuracy of micro/nano positioning platform.This thesis addressed the challenges of optimizing control methods in micro/nano positioning technology.An modified feed-forward P-I inverse model for eliminating the hysteresis of piezoelectric actuators was proposed.This thesis focused on the research on different control algorithms which can make micro/nano positioning platform track the desired displacement more accurate.The controlled object was the equivalent transfer function of micro/nano positioning platform,the main contents of this thesis are as follows:(1)Research on the performance of output displacement device.The working principle,hysteresis and creep characteristics of the piezoelectric ceramic actuator were mainly studied through theoretical analysis and experiment based on piezoelectric ceramic actuator PST150/4/7VS9.The different methods of applying preload force to the piezoelectric ceramic actuator and the analysis of the preload force-output displacement characteristic of' the piezoelectric ceramic actuator were discussed.We got a better understand of the mechanical properties of piezoelectric ceramic actuator,and provided a better preload way for the piezoelectric ceramic actuator.(2)Hysteresis nonlinearity makes negative effects on the output precision of piezoelectric ceramic actuators.Different hysteresis curves which have different velocity laws were described by the classical Prandtl-Ishlinskii(P-I)model.Parameters which contains weighting values and threshold values were identified by the method of quadratic programming based on least mean-square error rule.Tripartite P-I model can describe the asymmetry of hysteresis curves more accurately when compared with classical P-I model.The weighting values and threshold values of tripartite P-I inverse model can be calculated by the parameters we have got before.Tripartite P-I inverse controller was used to compensate piezoelectric ceramic actuator in the experiment.(3)Research on control method of micro/nano positioning platform.In order to improve the positioning accuracy of micro/nano positioning platform.The mathematical models of the piezoelectric ceramic actuator and micro/nano positioning platform were established.The transfer function was obtained by these mathematical model.Combined with the tripartite P-I inverse model obtained in previous studies,a feedforward-feedback compound control scheme was proposed.The performance of different controllers was studied by Matlab.The fuzzy PID controller was chosen as the controller of the closed-loop system finally.Experimental results showed that the tracking ability of tripartite P-I inverse controller was 81.3%higher than that of the classical P-I inverse controller.The simulation results showed that compared with the traditional PID controller,the fuzzy PID controller improved the tracking precision of the micro/nano positioning platform to the desired displacement by 80%.