Research On Structural Design And Drive Technology Of Three-Dof Piezoelectric Positioningp Latform

Micro-nano positioning system is widely used in a variety of ultra-precision machining,semiconductors,optics,aerospace and many other research fields to achieve high positioning resolution.Piezoelectric actuator has been successfully applied to many high-precision systems because of its small size,large output force,fast response speed,high resolution and so on.In this paper,in order to realize the precision alignment of optical devices and silicon electronic devices synchronously in a short time,a three-degree-of-freedom piezoelectric positioning scheme composed of piezoelectric ceramic stack and flexure hinge is proposed,and a Koopman depth predictor is constructed to improve the repeated positioning accuracy of piezoelectric stack due to hysteresis.The main research work is as follows:First of all,the micro-displacement amplifier is designed based on the elliptical flexure hinge.The piezoelectric stack and the flexure hinge mechanism are closely combined with each other to realize the displacement amplification of the piezoelectric stack.The micro-displacement amplifier is designed by using axisymmetric form and lever displacement amplification principle,and the performance of micro-displacement amplifier and piezoelectric positioning platform is simulated by Solidworks and ANSYS.Secondly,the depth predictor based on Koopman operator is constructed by using the depth neural network to improve the repeated positioning accuracy of the piezoelectric positioning platform caused by the hysteresis and creep characteristics of piezoelectric ceramics.The global linearization method based on Koopman nonlinear model is compared with the real data set to provide a model basis for subsequent controller design.Then,according to the electric control requirements of the piezoelectric ceramic stack,the flyback isolated high frequency transformer structure and the voltage type PWM control mode are selected to design the piezoelectric amplifier,which realizes the precise control of the piezoelectric ceramic actuator and positioning system within the allowable error range,and the host computer of the controller is designed by using NI PXI chassis and Lab VIEW software.Finally,the experimental system is set up and the experimental analysis is carried out.The positioning platform of single-degree-of-freedom piezoelectric ceramic stack and flexure hinge micro-displacement amplifier is built,and its performance is analyzed experimentally from the aspects of stroke,linearity and stability.Then the positioning experiment of the three-degree-of-freedom micro-displacement piezoelectric platform is carried out to evaluate the measurement error of the piezoelectric positioning platform,verify its linearity and stability,and test the positioning stroke in all directions and the minimum step displacement of the system.