Reasearch On The Control And Evaluation Of Piezoelectric Actuated Micro-positioning

With the rapid advancement of science and technology,micro/nano positioning technology has been extensively and deeply developed in many fields such as medical science,bioengineering,MEMS,and aerospace.Piezoelectric actuated micro-positioning platform system is commonly used in high-precision equipment,instruments,and high-precision operations due to its high precision,high resolution,high reliability,fast response speed,easy processing and control.Micro-positioning platform system is of great value in scientific research and production application.Therefore,based on the design and analysis of multi-degree of freedom,large stroke,high-precision flexible positioning platform,it is of great significance to improve the performance and accuracy of the micro/nano positioning system through intelligent control technology,so as to strengthen and improve the control system of micro positioning technology.The dissertation denpends on the Open Foundation of the Shanghai Key Laboratory of Space Vehicle.Starting with the six-degree-of-freedom micro-positioning platform,this dissertation has carries out the theoretical analysis of the hysteresis error,machining error and coupling error of the platform system,error compensation control strategy,software design and experimental testing,etc.The specific research content is as follows:(1)The composition and working principle of the micro-positioning platform system have been studied.The components of the micro-positioning platform system were discussed.The principle and characteristics of the driving device are analyzed.According to the theory of compliant mechanism and mechanical principle,the typical components of the micro-positioning platform have been compared and analyzed,and the types of flexible hinge and displacement amplification mechanism were determined.The amplification ratio and input/output stiffness of the bridge amplification mechanism have also been calculated by means of energy method,elastic beam theory and pseudo-rigid body model.(2)The hysteresis,machining and coupling error analysis methods of the micro-positioning platform system have been studied.The Preisach hysteresis model has been established.The back-propagation neural network training method was used to identify the hysteresis model parameters,and the hysteresis nonlinear relationship between the input voltage and the output displacement of the piezoelectric actuator has been obtained.Considering the structural parameters affecting the platform output displacement error on each degree of freedom,the machining error model has been established.By using the theory of space geometry and Lagrange equation,this paper has analyzed the coupling motion errorbetween multiple degrees of freedom of the platfor,calculated the dynamic parameters such as equivalent stiffness and equivalent mass,and made a comparative analysis through Ansys finite element simulation,which has lay a mechanical foundation for the subsequent control strategy design.(3)The error compensation control strategy of the micro-positioning platform system is studied.According to the electromechanical coupling equivalent transformation principle and dynamics theory,the dynamic equation of the micro-positioning platform system has been established,and the open-loop transfer function of the system has been derived.For the hysteresis error,machining error and coupling error,the inverse Preisach hysteresis model has been established as feedforward compensation,and the three control algorithms of PID,back propagation neural network PID and fuzzy cerebellar model neural network PID have been designed as closed-loop control compensation.Matlab/Simulink simulation analysis has also been carried out to discuss the optimal control strategy for system error compensation.(4)The error compensation experiment test and evaluation of the micro-positioning platform system has been studied.Based on the six-degree-of-freedom micro-positioning platform prototype and the experimental instruments,the experimental device of the micro-positioning platform system has been built.The software integration of the drive and detection device has been realized by using Labview software,so as to implement the closed-loop control experimental environment of the system.The open-loop hysteresis,open-loop inverse hysteresis compensation,closed-loop control compensation and coupling compensation experiments of the micro-positioning platform system have been carried out.The performance indexes such as the hysteresis error,maximum error value,maximum tracking error,root mean square error and displacement coupling ratio of each degree of freedom have been analyzed to verify the effectiveness of the system error compensation control strategy and evaluate the compensation effect of the control strategy.