Research On Monitoring System For MIG Backing Welding Of Pipeline Based On CCD Sensor

It is a world-wide technological puzzle to implement the welding automation and quantity control. Couple with the development of national economy, petroleum, nuclear power, medication and some others industries are raising a more strict claim of the quality and efficiency of welding. Backing welding is a very vital step in pipeline, MIG (Metal Inert Gas Arc Welding) has been paid more and more attention by virtue of its high efficiency and user-friendly feature recently. However considering the uncertain factors of welding process, it has been impossible to effectively solve the problems only depending on power source and welding procedure. Therefore, this thesis will do a research on monitoring system for MIG backing welding of pipeline based on CCD (Charg-coupled Device) sensor.This topic is patronized by special fund of Jiangsu province, and is developed by the original facility of HUAHENG Welding Co.,Ltd., which mainly studies the key techniques effecting system’s performance. Meanwhile, it makes an intensive study on the CCD vision sensor, effective image processing algorithms and real-time control based on multiple-thread.Aimed at the problem of big noise of MIG welding, we construct passive vision sensor system based on CCD; we put forward the method of calibration based on threshold auto-division and linear fitting, a algorithm of edge extraction based on mathematic morphology and Chan-Vese active contour mode,plus a method of seam detection based on molten pool and sobel filter, by means of analyzing the gained images; we also fix the position of weld joint by using weighted average. The experimental results show that the image processing algorithms in this thesis elevate the accuracy of target location effectively. And we put forward real time control method based on PID control in order to complete the seam tracking process. What’s more, we fuse the above-mentioned key techniques into the development of system software, and develop a monitoring system for MIG backing welding of pipeline based on CCD sensor, which can be used for doing the welding experiment of several pipes and leads to a good weld appearance by meeting the demands of welding process.