Vision based measuring system for both weld pool and root gap in continuous current GTAW

摘要

A low cost vision based measuring system is developed to detect both the weld pool geometry and root gap simultaneously. Efforts are made from both hardware and software aspects to decrease the strong interference from arc light during gas tungsten arc welding (GTAW) process with continuous current. A normal charge coupled device (CCD) camera is cooperated with specially made composite filter lens and the video signals before A/D conversion are adjusted according to the welding current. Clear images of both root gap and weld pool are captured under different welding parameters. The grey level distribution characteristics of root gap edges and weld pool edges in images are analysed and utilised for developing the algorithms for image processing. The continuum of weld pool edge and the linear features of root gap are also utilised in the algorithm. The results show that the algorithms can extract the weld pool edge and root gap edge effectively. A solid foundation for weld seam tracking and weld penetration control by a single sensor is thus established.