Research On Compensation Algorithm For Cam Grinding Based On Equivalent Error

In the field of automotive,textile,food,mechanical transmission and so on,the cam is the most common mechanical rotation or sliding member,cam grinding is a typical non-circular grinding processing,while the accuracy of cam grinding is a very important topic,how to improve the grinding Cutting accuracy is our top priority.In high-performance production,CNC cam grinding machines have basically replaced the traditional rocker arm type machines,greatly improving the grinding precision of cams.The grinding precision of the cam is directly reflected on the profile error of the cam,so the grinding accuracy of the cam is regarded as a problem to reduce the error of the cam contour.In the grinding method,most of the researchers for the approximate contour error as the object to design the controller,this paper introduces the concept of equivalent error,direct control of contour error true,avoid the error of numerical calculation of approximate contour error caused,according to this the concept of equivalent error of the controller design,which directly to the real contour error compensation control.The main contents of this paper are as follows:1.Preparation work before grinding,in order to make the application of equivalent error method to the cam grinding platform and maintain the original characteristics of the cam curve,based on the original data provided by the manufacturer through inversion method and mathematical model to obtain the input sequence of linkage system,due to the use of equivalent errors method must have the implicit function,Then the three non-uniform B-spline inverse algorithm is used to deal with the sequence value,and the interpolation algorithm is prepared for the real-time interpolation of B spline curve.2.The basic concept of equivalent contour error is introduced.Taking the equivalent contour error as the controlled object,the B spline curve is interpolated in real time to provide the given instruction value,and the implicit function is obtained as the equivalent contour error through the parameter formula of the B spline interpolation curve.The implicit function is obtained through the Cayley 's method of the Bezout form,The basic concepts needed for the B spline interpolation algorithm in this paper are given,and the validity of the B spline interpolation algorithm is verified.3.Secondly,the nonlinear equivalent error model of the cam grinding platform is established by using the equivalent error and the tangent error as the controlled object.The problem of cam grinding is transformed into a problem of stabilization.The feedback control is applied to design the new control input,and then the controller is designed by pole placement to make the equivalent error and tangent error move to zero and stabilize the system.The simulation experiment shows that this method can effectively improve the grinding precision of the cam and reduce the profile error.4.The controller based on feedback linearization and pole placement can not completely offset the influence of uncertain factors on the cam grinding platform.A more robust equivalent integral sliding mode control method is applied to cam profile error compensation,and the uncertainties and disturbances in the system are analyzed.The simulation results show that this method not only inhibits the influence of uncertainty on the performance of the system and improves the grinding precision of the cam.5.Finally,in order to weaken the chattering caused by the equivalent integral sliding mode control switching coefficients of the impact on system performance,and then the RBF neural network algorithm is applied in the control system for adaptive approximation switching coefficient,so as to weaken chattering and improve grinding precision.In this paper,CNC cam grinding platform is taken as the research object.And the simulation of the above strategy is carried out.The results show that the cam grinding algorithm based on feedback linearization and pole placement can effectively improve the grinding precision of the cam,and has good anti-interference performance.when the uncertainty factors in the system,we need more robust controller,the feedback linearization and integral sliding mode equivalent control can effectively solve this problem and improve the grinding precision,and at the same time using RBF neural network algorithm adaptive approximate switching coefficient to eliminate chattering,the grinding accuracy is further improved.