Research On The Measurement System Of The Five-degree-of-freedom Geometric Motion Error Of Guide Rail

With the progress of science and technology,the manufacturing industry has made great progress,and the demand for high precision and even ultra-high precision has also followed.CNC machining center and CMM,as a common equipment in manufacturing industry,are important to ensure the machining accuracy of products.As an important component of the 21 spatial geometric errors of these devices,the measurement of geometric errors of linear guide rail is undoubtedly the most important.The geometrical motion error of single-axis linear guide consists of six parts,including horizontal straightness error,vertical straightness error,positioning error,pitch angle error,yaw angle error and rolling angle error.It is an important way to ensure and improve the machining accuracy of the machine tool to realize the accurate measurement of 6-DOF geometric motion errors.The traditional measurement method or debugging process is tedious,which can only measure a single degree of freedom at one time.Or the system design is complex and expensive.Or the structure is simple,but the accuracy is not up to the requirements.Therefore,it is of great significance to study a measuring system with high precision,low cost and easy to use,which can simultaneously measure the geometric motion error of multiple degrees of freedom of linear guideway.In this paper,based on the laser measurement technology,the collimation measurement and angle measurement are combined through the optical path design to realize the simultaneous measurement of 5-DOF geometric motion errors of the guide rail.In this study,a semiconductor laser was selected as the laser source,and a single beam was divided into two beams by a polarizing beam splitter and quarter wave plates.After the first transmitted light reached the sensor end,it is divided into two beams through the spectroscope,which were respectively used for collimation measurement,pitch angle measurement and yaw angle measurement.The second beam was adjusted by the reflector,and was kept parallel with the first beam for collimation measurement.The horizontal straightness error,vertical straightness error and rolling angle error were calculated by converting the measurement results of two collimating four-quadrant detectors.Finally,simultaneous measurement of geometric motion error of 5-DOF in linear guide rail was realized.This system has the characteristics of high integration,small volume,high measurement accuracy and easy installation and use.In this study,the optical path design,mechanical structure design,upper computer software programming,system construction and equipment debugging of the measurement system were completed,and the accuracy of the measurement system was tested.The experimental results show that he stability and repeatability of the system were good.On the800 mm distance of guide rail,the accuracy of straightness measurement is ±2?m in the range of ±100?m,the resolution is 0.05?m.The accuracy of angle measurement is ±3.0?in the range of ±100?,and the resolution is 0.5?.In order to improve the accuracy of the measurement system,the error sources of the measurement system were analyzed,and a ridge regression algorithm based on machine learning method was proposed.Experimental results shown that compared with the traditional algorithm,the machine learning method can improve the accuracy by 75.8% compared with the traditional positioning algorithm of four-quadrant photodetector,which has important application significance.