Vision Based Welding Seam Detecting And Tracking

In the manufacture industry, welding automation not only can free the workersfrom hard work, but also enhance the efficiency and accuracy of the work. Thus it is ofgreat importance. With the rapid development of various kinds of sensors, the visionbased automatic welding is coming into consideration all over the world. In this paper,firstly the current situation in the study of vision based welding seam tracking systemare introduced, then the recent algorithm is improved, and the new welding seamtracking system based on the structure light vision is realized.In this paper, the whole software of the structure light vision based welding seamtracking system are designed and realized. First, the image of the welding seam withstructure light is captured, then the feature points of the welding seam are found bydoing digital image processing on the captures image, after the pixel coordinate of thefeature points are determined, they are transformed into the world coordinate of thewelding robot to control the motion of the welding gun. Then the automatic weldingseam tracking task is thus completed.To fulfill this task, quite a few things need to be done, such as the building of thesystem software structure; the actual calibration of the whole vision system to get thetransform relationships between different coordinates such as the image plane, thecamera coordinate, the end effecter coordinate and the robot world coordinate. Here animprovement has been made to get better hand-eye calibration result. After lots of studyof different kinds of image processing strategies, the welding seam feature points arefound in different ways and the results in accuracy and speed are compared, eventuallya new structure light center extraction method with better results is found; In the end,the model of the welding robot is built up based on the physical structure of the robot,and the data transformation between PC and the robot are realized through Ethernet tocontrol the motion of the robot. As the experiments showed, the system built in thispaper can fulfill the automation tracking of the welding seam with the speed of5mm/sand accuracy within0.3mm, so it can indeed reach the requirement of the welding job.