Automation of Arc Welding for Large-Scale Structures by Visual Sensor. Reliable Detection of Weld Lines.

In the automation of arc welding using visual sensors, it is necessary to precisely detect the weld line. However, for large scale structures, such as the steel tube transmission towers examined in the present study, it is not easy to maintain the reliability of weld line detection. Therefore, assuming that welding data among structural parts, including positions and directions of their contact points and lines, can be easily obtained from CAD data, and utilizing the fact that the current torch position is known all the time, we have proposed image processing algorithms to reliably detect only the welding area with a specified direction, and to precisely detect the welding line for torch position control. The proposed algorithms have been applied to a test piece placed on an experimental system, and continuous tracking along the welding line by measuring the welding gap has been presented.