Research On Contour Tracking Control Strategy Of Three-dimensional Precision Motion Platform

With the acceleration of industrialization,the accuracy of NC machining is getting higher and higher.It is an important trend to ensure high-precision contour processing in the development of NC machine tools.Thesis paper takes the three-axis motion platform driven by permanent magnet synchronous linear motor as the research object,aiming at the problem that the servo system is susceptible to external disturbances,friction and other non-linear disturbances,and that the traditional contour error estimation model is inaccurate when facing different trajectories.Firstly,position controller is used to ensure the accuracy of contour tracking and the anti-interference ability of the whole system.Secondly,dynamic contour error estimation method is used to complete the error model of the system.The research contents are as follows.Firstly,the mathematical model of single axis of three-axis motion platform is analyzed,and on this basis,the mathematical model of the three-axis motion platform is established.Then the contour error of the three-axis motion platform is analyzed.The traditional modeling method of the spatial contour error is introduced,and the factors affecting the system contour error are analyzed.Then,in order to satisfy the requirement of high precision of servo system,and considering the robustness of servo system,a method combining adaptive robust control with RBF neural network is proposed.In the position loop of servo system,the neural network learning adaptive robust control method is adopted.The adaptive robust control combines the advantages of adaptive control and deterministic robust control.It can ensure that the system has better robustness in the presence of non-linear disturbances,and at the same time,the system can meet the tracking requirements of high precision.Secondly,the approximation characteristics of RBF neural network are used,in order to approximate and compensate the complex disturbances in the system,the tracking accuracy of the system is further improved.Finally,in order to further improve the processing accuracy of the system,the contour error estimation method based on Newton's extremum search algorithm will be used to achieve more accurate contour error estimation.After the estimated contour error is passed through the iterative learning controller,the input of the position command of the reference trajectory will be adjusted directly.The validity of the design method is verified by building a three-axis motion platform system under MATLAB/simulink.The simulation results show that the control method can effectively improve the accuracy of contour processing.