Position Prediction Simulation And Experiment Study For CNC Rotary Table

CNC technology is related with the national strategic status closely and it reflects the nationalcomprehensive national strength level of fundamental industry. CNC rotary table is the indispensablegeneral function parts of CNC milling machine, CNC boring machine, milling center and other CNCmachine tools. The level of CNC rotary table influences the decision and the performance of thenumerical control host directly. Time grating was a brand new principle displacement sensor oftime-space coordinate transformation. It reduced the processing difficulty and the cost and enhances theability of greasy dust and intelligent because it completely avoids the precision machinery scribed line.With the time gating as angle measuring elements in the closed-loop CNC rotary table, the cost can begreatly reduced. So it can be widely applied in all kinds of environment and will be widely accepted.While time gating is a static absolute type measuring sensor according to the time divide the sample, soit can’t conduct whole closed-loop position feedback directly according to the time equally. In order tosolve the key technical issues, the main research contents for the project were as follows, which were inthe support of the national natural science funds:1. The error of dynamic position feedback in the whole closed-loop CNC rotary table wasresearched, which was brought by the time gating as angle measuring element.2. The theory and method of prediction measurement was researched. To model through based onthe analysis of the present and past measured value, and measured the value of a period of time in futurecan be predicted and position feedback on to solve dynamic position feedback error problem. A newtechnology principle for making discrete measurements to continuous space position signal with timeseries is presented. The static measurement sensor used in dynamic continuous position feedback,through to the discrete of measurement value of continuous treatment.3. The turntable position prediction measurement modeling based on time series was researched.Based on the analysis of the time series analysis theory and time series data pretreatment methods, autoregression model, the solution of the coefficient, model inspection, the best prediction and thecorrection method were presented.4. The dynamic prediction error separation and real-time fixed theory and method of CNC rotarytable space position were researched. A correction method of standard point dynamic prediction errorcorrection model to discrete the standard quantum insertion real-time error with the standard quantity ofthe practical measurement value is presented.5. A stable data sequence can be obtained though the analysis of time grating angle measurementvalue. The three regression model was set up to achieve high accuracy of the prediction of turntable position. The experiments and simulation results show that, the off-line prediction error of spaceposition of CNC rotary table is within±2″, dynamic prediction error is±4″, indexing system error oftime grating CNC rotary table is5″.