Research On Machine Vision 3D Imaging And Its Measurement Technology

With the improvement of the flexibility and intelligence of the manufacturing industry,the fully automatic 3D measurement technology has been increasingly used,3D measurement can obtain 3D dimension information of workpiece blank in real time,And transmit its spatial point cloud coordinate information to the machining center,In this way,the automation of the first cutting operation is realized,and the foundation for the unmanned intelligent operation of subsequent processes is laid.Based on the analysis of the measurement requirements of automated production lines,this paper studies the three-dimensional scanning measurement technology combining multi-line structured light and binocular vision.Firstly,this article addresses the 3D imaging and measurement needs of workpieces,analysis of the basic principles of binocular stereo vision system.By comparing the currently used camera calibration methods,the plane template method of Zhang Zhengyou was used to calibrate the binocular stereo vision system,the internal and external parameters of the binocular camera were obtained.And the calibration results were used to perform distortion correction and stereo correction to prepare for subsequent binocular matching.Then,the basic characteristics of the laser stripe were analyzed,and related methods of the laser stripe image preprocessing were studied.The appropriate filtering and segmentation algorithm was selected based on the characteristics of the laser stripe image and realized the accurate extraction of the laser stripe center point by using the Hessien matrix algorithm.Aiming at the matching problem of multi-line laser light bars,a method combining stereocorrected epipolar constraints and order consistency constraints was proposed to quickly match the center of the laser light bars in the left and right images.Based on the matching point pairs on the left and right images obtained before,the centerline of the laser light bar was used to three-dimensionally reconstructed according to the principle of triangulation.Using the space coordinates of all landmark points to establish a global coordinate system by the way of pasting landmark points on the surface of the object.During the scanning process,the point cloud data reconstructed from multiple perspectives can be quickly converted to global coordinates.Finally,the 3D point cloud results of the entire object surface were obtained,then the 3D reconstruction of the object was completed.Finally,a multi-line laser light bar 3D scanning measurement experimental platform was designed and built.The structural parameters of the binocular stereo vision system were analyzed,and the visual interface of the experimental platform was designed.The detailed measurement process is given according to the control interface.Lastly,the experimental platform was used to carry out three-dimensional measurement experiments on planar feature workpieces and curved feature workpieces.Then the obtained experimental data was compared with the actual measurement data of the object.The experimental results show that the measurement method has better measurement accuracy and stability.