The Three Dimensional Information Measurement Of Weld Seam Based On Machine Vision

Weld seam exists in a large number of industrial occasions.There is residual stress in the weld,and its rough surface is easy to cause stress concentration,therefore,weld grinding has become an essential processing procedure after welding.With the wide application of robots,automation of weld grinding has become a main development trend.Therefore,this paper studies the grinding of the weld after welding,and measures the three-dimensional information of the weld based on machine vision to provide data support for the automatic grinding of robot.The main research contents of this paper are as follows:(1)Establishing a three-dimensional information measurement platform for weld seam based on line laser vision.The sensing mode of vertical receiving by CCD industrial camera and oblique illumination by laser is determined,and the important components are selected.The line laser vision sensor is built by binocular bracket.(2)Studying the calibration algorithm of line laser vision system.The measurement principle of line laser vision system is described in detail,and the line laser vision measurement model is constructed.The calibration of the line laser vision system is completed through experiments,and the camera calibration results and line laser plane calibration tests are carried out.The experimental results show that the final calibration measurement model meets the accuracy requirements of three-dimensional information measurement of the weld seam.(3)Studying the image processing algorithm and feature information extraction algorithm of welding seams.Aiming at the laser weld image,the gray distribution characteristics of the image are analyzed.The projection method is used to determine the ROI area of the weld.The median filter is used to remove the noise interference compared with different filtering methods,and the binary image of the weld is obtained by the maximum inter-class variance method.The center line of laser fringe is obtained by skeleton refinement method.Finally,the pixel points on the center line of laser is iterated to obtain the weld characteristic information.(4)Developing machine vision weld grinding system and conducting weld measurement experiment.The machine vision welding seam grinding system is developed jointly with QT and Open CV.The three-dimensional information of the welding seam is measured by the system and the grinding path is fitted.The accuracy of the measurement system is verified by comparing with the manual measurement results.