Experimental determination of weld pool geometry in gas tungsten arc welding

Based on the analysis of the gas tungsten arc welding (GTAW) arc spectrum, a composite light filter is designed. This filter and a normal charge coupl ed device camera form a vision sensor, which observes the GTAW weld pool fr om the topside of the workpiece. During the welding process, the captured i mage brightness is adjusted according to the magnitude of the welding curre nt using software, and comparatively distinct images of the weld pool are o btained. The weld pool geometry is measured through an image processing alg orithm developed by the present authors. The algorithm requires less than 7 0 ms to process an image frame in a 100 MHz main frequency computer, and th erefore meets the requirements of real time measurement.