Visual sensor based weld seam tracking method for precision pulsed TIG welding

In order to solve the weld seam tracking problem in the pulsed TIG welding process of some thin stainless steel workpiece with complicated curved surface, a high-precision rapid-response weld seam tracking method based on visual sensor was developed. According to the process characteristics of pulsed TIG welding, special wavelength filter and reasonable exposure schedule were selected, while the clear and amplified welding image (from which weld seam, weld pool and tungsten electrode could be identified directly) could be acquired with industrial CCD camera. An image processing algorithm was programmed with Visual C language, by which the central line of weld seam could be detected rapidly and precisely, the direction and distance that the tungsten electrode deviates from the central line of weld seam could be calculated, and the step motor could be driven to adjust the position of welding torch. Therefore, the precise and real-time weld seam tracking is realized.