Research Of Control Methods For Stick-Slip Inertial Piezoelectric Actuator

The stick-slip inertial piezoelectric actuator has the advantages of large stroke,high precision and fast response speed.It is widely used in precision manufacturing,biomedicine,micromanipulation and other fields.Its positioning control technology is an important basis for its industrial application.In this paper,the stick-slip inertial piezoelectric actuator is taken as the research object.In view of the complicated friction-motion relationship of the actuator itself,the modeling is not accurate,and the positioning control accuracy is greatly reduced due to the uncertain disturbance,an adaptive PID closed-loop control strategy based on single neuron is introduced.And a model-free adaptive control scheme based on disturbance estimation is proposed.The aim is to compensate the influence of negative factors on the precision of positioning control by optimizing the controller.The specific research content of this paper is as follows:(1)According to the closed-loop control principle of stick-slip inertial piezoelectric actuator,a micro-positioning system based on hardware equipment and measurement and control software is built.Among them,the hardware system includes displacement sensing equipment,data acquisition equipment,power amplification equipment,actuator prototype,upper computer,etc.The software system is written by Lab VIEW and MATLAB mixed programming,and realizes man-machine interaction,data acquisition,control algorithm call,analog driver signal generation,process data saving and other functions.The motion mechanism of stick-slip inertial piezoelectric actuator was analyzed and studied.Based on the dynamics equation of the second-order spring damping system,the Lu Gre friction model was introduced to describe the friction motion relationship between the input and output of the actuator.The model was verified by MATLAB/Simulink.(2)Aiming at the problem that the positioning control accuracy of stick-slip inertial piezoelectric actuator decreases when the starting and ending positions change due to the friction coefficient change caused by wear and tear,an adaptive PID closed-loop control strategy based on single neuron is proposed.Firstly,the closed-loop control principle of amplitude and frequency is studied,and the output threshold of amplitude and frequency control is set to improve the adaptive ability of the controller and ensure that the actuator can achieve high precision positioning stably and quickly.Then,on the basis of modeling research and micro-positioning system platform,simulation and experimental verification are carried out.By comparing with the traditional PID control strategy,the proposed control strategy is proved to be effective.(3)The model-free adaptive composite controller based on RBF neural network disturbance estimation was proposed to solve the problems of difficulty in modeling the stick-slip inertial piezoelectric actuator and uncertain disturbance affecting the positioning control accuracy.Firstly,a model-free adaptive compound control law based on data drive is designed to avoid complex modeling process.On this basis,the RBF neural network disturbance estimator is introduced to make up for the influence of perturbation on the precision of positioning control by accurate estimation of generalized uncertain disturbance.The limit theory is used to prove the controller error convergence and output bounded,and the asymptotic stability of the controller is analyzed.Finally,in order to better verify the effectiveness of the control strategy,test experiments are carried out on the micro-positioning system platform.The positioning control accuracy of the model-free adaptive composite controller with disturbance estimator is significantly improved.