Spatial Coordinate Correction Of Coordinate Measuring Machine Based On Tracking Multistation Measurement

With the development of modern precision manufacturing and measurement technology,modern industry in increasing the demand for coordinate measuring machine(CMM).At the same time,it also put forward higher requirements on the accuracy of the CMM.At present,the ways to improve the measurement accuracy include improving the mechanical precision and correcting the measurement error.We found that the cost of improving the mechanical precision is very high and difficult to achieve.But to be compared,another method only corrects the measurement results,it is low-cost,efficient and large-scale application.Most of the traditional error correction methods can not correct the random components in the measurement results,with some limitations.But LaserTracer has the advantages of fast measurement speed and high precision,and easy to realize the tracking measurement of spatial coordinates.Therefore,the use of LaserTracer to achieve error correction of CMM has become an important work.The purpose of this work is to study the spatial coordinate error correction technology and turntable angle calibration technology of CMM on the basis of Laser Tracer multistation measurement system.Set up the measurement models and choose the suitable correction methods for CMM or turntable,and then verify the feasibility of the method by experiment or simulation.The main contributions of this reaserch are as follow:(1)Based on the principle of interferometric length measurement of LaserTracer,a multistation measurement model of laser tracker is established.The selfcalibration of station coordinate is used to get the station coordinates.The Taylor series expansion error equation is used to get the coordinate correction value of the measurement point.(2)Based on the multistation measurement model of LaserTracer,the spatial coordinate error correction technique of coordinate measuring machine is proposed.This paper choose two following methods to correct the spatial coordinate error of CMM: First,fix the path of Cat-eye,mesh the measurement space,get the correction value of the measured point which are at the grid nodes,get the correction values of measurement points in the measurement space by three linear interpolation.Second,the measurement method for the measured object,determine the measurement path according to the shape of the workpiece,and correct the measurement results by using the multistation measurement of LaserTracer.(3)Researching on angle calibration method of turntable.Estabish the calibration model of turntable;propose a method to improve the accuracy of station coordinates by improving the accuracy of calibration;convert the station coordinates of the Laser Tracer to the rotation error of the turntable;fitting the error curve by using the discrete angle error.(4)According to the previous models,the Global Performance CMM is calibrated by the LaserTracer from Etalon which verifies the model;Through the simulation experiments,the calibration method of turntable angle based on multistation measurement by LaserTracer is verified.