Research On Contour Error Pre-compensation Method Based On Fuzzy-logic Control Of Feedrate

With the growing of modern advanced manufacturing,CNC machining technology has been widely used,and the contour accuracy of CNC machining has become an important performance index of CNC machine tools.The contour accuracy of CNC machining directly determines the machining quality of the part,and the measurement of the contour accuracy is contour error.Therefore,the research on contour error compensation and controlling in CNC machining process is of great significance for achieving high-speed and high-precision machining.Firstly,the simulation model of the two-axis motion platform and the contour error estimation model of the parametric curve are built.The closed-loop transfer function of the feed drive system is obtained through the identification method,and the corresponding simulation model of the feed drive system is built.Then,a contour error estimation model based on the tangential error is proposed.By finding the position point on the parameter curve step by step till it’s closest to the desired contour error foot point,the contour error can be accurately estimated.And,this contour error estimation model can be applied to the complex curve trajectory and meet the real-time and high-precision requirements at the same time.Secondly,a control strategy combining the contour error pre-compensation method and the feedrate fuzzy controller is designed.The contour error pre-compensation method can predict the contour error before it is generated,and then compensate the contour error to the commanded path to correct it.Thereby the overall contour error can be reduced effectively.In addition,considering the influence of feed rate on the contour error during the machining process of large curvature curves,a feed rate regulator based on fuzzy control strategy is designed to reduce the local abrupt contour error,which can reasonably adjust the feed rate according to the predicted contour error and its variation value.Through the combination of the contour error pre-compensation method and the feed rate regulator based on fuzzy-logic control,the contour error problem caused by the complex and diverse influencing factors in the machining process can be effectively solved.Finally,the contour tracking motion control experiment of typical curve trajectory was performed on the two-axis XY motion platform.The contour tracking motion control experiments of three sets of free parameter curve trajectories were carried out on the XY two-axis motion platform under the two experimental conditions of with or without the proposed control strategy.Then calculate and analyze the reduction ratio of the mean value and the maximum value of the contour error in the three sets of contrast experiments.And the results show that the proposed control strategy can effectively improve the contour error of free curve trajectory and improve the contour accuracy.