Research On Calibration Technology Of Laser Line Scan 3D Measurement System

In the context of the accelerated deployment of "Made in China 2025",with the development of high-tech industry finishing and industrial Io T technology,and the continuous increase in requirements for non-contact measurement,it has high accuracy,good stability,Laser scanning measurement with advantages such as fast response has become an important branch of the three-dimensional digital measurement research field,and it has been widely used in different scenarios such as industrial production,cultural relics archeology,and 3D ecommerce.The calibration accuracy of laser scanning measurement system is a key factor affecting the accuracy of 3D measurement.Therefore,researching high-precision calibration methods is of great significance to the field of laser 3D measurement.This paper focuses on the relevant methods involved in the calibration of laser line scanning 3D measurement systems.The main work includes the following three aspects:Firstly,a quadratic weighted gray center of gravity algorithm with adaptive width is designed to extract the center of the laser fringe,and the average value of the extracted center point is further optimized based on the slope threshold.This paper studies the identification and location of the center of the laser fringe,pre-processes the optical fringe using adaptive median filtering,automatic global segmentation,and morphological operations;the light is obtained using a quadratic weighted gray center of gravity algorithm and mean optimization The sub-pixel center coordinates of the feature points.Experiments show that this method can effectively reduce the influence of factors such as on-site environmental interference,image noise,and surface material of the object to be detected in fringe extraction,and improve the accuracy of the laser light strip center extraction.Secondly,a laser line scan probe with a single camera and a single line laser is constructed in this paper,and its digital model construction and parameter calibration method are studied.The camera is calibrated with a circular target point plane target,and the internal parameters of the camera and the corresponding change matrix are obtained.Several calibration methods of light plane parameters are studied,and high-precision light plane calibration is performed based on projective transformation.The process is simple,complex calculations using cross ratio invariance are avoided,and the number of available light plane calibration feature points is not limited.The experimental results show that this method can improve the accuracy and robustness of light plane calibration.Thirdly,in order to obtain the surface profile information of the object,a scanning measurement system with two methods of translation and rotation is set up.The calibration of the auxiliary motion device was studied to determine the relationship between the data obtained at different positions and the coordinate system of the measurement system.A standard ball is used to eliminate the deviation of the scanning direction of the light bar due to the installation error in the translational scanning measurement.The rotation axis calibration is studied using a flat target,and the feature points of the measurement data are fitted with a space circle according to the least square method.Correlative optimization methods were used to improve the accuracy of the center of the circle.Finally,the space center was fitted to the center of the circle to obtain calibration parameters.The experiment verifies the validity of the calibration algorithm and realizes the 3D data collection and measurement of the object.