Research On Contour Control Of Linear Motor Platform Under Aberrancy Coordinate Transformation

The precision machining technology of CNC machine tool is a key technology since the industrial revolution,which has an irreplaceable role in the development of various industries.However,with the continuous development of modernization process,the precision requirement of CNC machine tool has become higher and higher,and the requirements for contour performance have also become higher.Therefore,in order to meet the needs of industrial production and manufacturing,this paper relies on the national natural science foundation of China to make an in-depth study of contour error,so as to meet the goal of high-precision machining.The main contents of this paper are as follows:(1)Due to the uncertainty of parameters,a series of problems such as vibration occur in the process of machine tool manufacturing in the existing contour error control algorithm.In order to meet the demand of higher machining accuracy,this part summarizes the estimation method,control method and compensation strategy of contour error based on the current research status of contour motion control.(2)In this part,the software Bode Tool is firstly used to collect the frequency domain data and Bode diagram of the X-axis and Y-axis of the linear motor platform.Then,the acquired data are analyzed in the frequency domain of the control system to determine the order of its dynamic equation.Then a sliding mode control algorithm is designed to construct a dynamic model of contour error based on polar coordinate system.In the simulation of the regular curve("large curvature ellipse ")and the model constructed by the traditional cartesian coordinate system,the results show that this algorithm can obtain better contour performance,but the estimation of contour error is still insufficient where the curvature is relatively large.(3)The limitation of the contour error control method based on polar coordinates,and in order to further reduce the contour error of the control system,an estimation method based on the third-order Taylor regular expansion approximation contour error is designed.First of all,based on the Aberrancy coordinate transform the establishment of a complex regional rate curve contour error estimation model;Then,the control algorithm is designed according to the dynamic model of contour error and the contour motion control simulation is carried out according to the designed desired contour.Finally,compared with the traditional model of contour error estimation,the simulation results show that the control method proposed in this chapter has better contour control effect.(4)In order to further improve the control accuracy of contour error,and considering that the contour error data has a certain degree of timing and fitting,this part chooses the method of deep recursive neural network LSTM based on deep learning to fit and predict the contour error model and then compensate the actual input.The simulation results show that the lstm-based compensation strategy has better control accuracy and the contour error is further reduced compared with the traditional contour error compensation strategy.(5)Finally,based on the multi-axis linear motor movement platform,the contour movement control experiment is carried out,and the results show that the proposed method can make the multi-axis linear motor machine tool operation more stable.At the same time,the contour error is well controlled.In the irregular trajectory test with high curvature,good contour performance is still guaranteed.