Path restriction and speed regulation via force feedback-type welding teaching device using magnetorheological brakes

Welding is one of the forms of nonautomated, heavy labor used in the shipbuilding industry. In the shipbuilding process, the hull is first welded by an industrial automatic welding machine, then irregular welded part correction and welding in narrow places that machines cannot reach are performed by welding workers. Welding operators are required to weld indeterminate objects in narrow working spaces. In addition, it is difficult to perform high-quality welding because the ability to accurately trace a welding line at a constant speed requires a long training period. In this research, a welding training device that assists trainees in skill acquisition was developed. The proposed device, which comprises two magnetorheological (MR) brakes, renders a welding path and restricts welding speed. The MR brakes have a response speed comparable to that of powder brakes, have a high output-to-weight ratio, and are also considered to be suitable for use in welding training devices. A prototype and control strategy were developed, and the performance of the device in actual welding work was evaluated. Results shows that path rendering strategy is possible to present routes with an accuracy of 1 mm or better and speed control strategy can regulate the speed required for welding.