Research On 3D Reconstruction Technology Of Welding Pool Based On Binocular Structured Light

With the rapid development of intelligent robots,welding robots have been widely used in shipbuilding,steel construction,aerospace and railway bridge industries.Due to the shortcomings of welding robot in 3d reconstruction and visual recognition of welding pool line,it cannot realize intelligence,flexibility and real-time control,and cannot guarantee the quality of welding operation.In this paper,starting from the study of online 3d reconstruction technology of welding pool,aiming at the problem of arc light interference in the welding process,a 3d reconstruction technology method of welding pool based on binocular structure light was proposed,and an online welding experiment platform based on visual recognition system of binocular structure light was built.The main research work of this paper includes:(1)Aiming at the calibration problem of binocular camera,the imaging principle and camera distortion factors of monocular camera were studied,and the binocular stereo vision imaging model and camera radial tangential distortion model were established.Based on the established binocular stereo vision imaging model,the matching relation of corresponding points was established based on the principle of antipole geometry,and the antipole constraint equation containing the internal and external parameters of the camera was obtained.This paper analyzes the principle of zhang zhengyou single target method,deduces the calibration algorithm of binocular camera,carries out the calibration experiment of binocular camera,and obtains the internal parameter,external parameter matrix and distortion coefficient of monocular camera.Reprojection error analysis is carried out to verify the accuracy of calibration results.(2)In view of the complexity and slow speed of the phase-shift fringe unwrapping algorithm,the principle of gray code image encoding and decoding is analyzed,and the basic working principle and phase unwrapping algorithm of phase-shift method are studied.Based on the advantages of easy and fast decoding of gray code,a hybrid structured light system combining gray code and phase-shift fringe is established,which makes the phase-shift fringe expansion algorithm simple and fast.The generation law of sine grating is studied and the standard sine grating pattern is obtained.The maximum probability correction method is used to correct the period.(3)Aiming at the difficulty of 3d reconstruction of welding pool caused by arc light interference in the welding process,the working principle of the mixed structure light system of binocular stereo vision system and gray code combined with phase shift fringe was analyzed.A binocular structured light visual recognition system was established,the measurement principle of binocular structured light system and the matching algorithm of corresponding points were studied,the arc light interference problem was solved,and the three-dimensional reconstruction algorithm of welding pool was derived.The welding pool data were pretreated,the outliers were filtered and the data compensated to reduce the influence of data errors on the reconstruction results.Based on the built binocular structural light visual recognition acquisition platform and online welding experiment platform,the 3d reconstruction experiment of welding fusion pool was conducted,and the deviation of 3d reconstruction model was analyzed to prove the feasibility of 3d reconstruction technology of welding fusion pool based on binocular structural light.