Vision-based measuring of weld pool geometry in TIG welding

Based on the analysis of tungsten-inert-gas (TIG) welding arc spectrum, a composite filter len has been designed. This len and a normal CCD camera form a vision sensor which can observe the TIG weld pool from the front side of workpieces. During welding process the captured image brightness is adjusted according to the magnitude of welding current by means of software, and comparatively clear images of TIG weld pool are obtained. The weld pool geometry was measured through the image processing algorithm developed by the authors, which takes less than 70 ms to process a frame of image and meets the requirement of real-time measuring.