Path rendering and velocity restriction with welding-assisting device composed of magnetorheological brakes

Abstract In the shipbuilding industry, welding is one of the forms of nonautomated heavy labor, and the welding operator is required to weld indeterminate objects in a narrow working space. Therefore, it is difficult to use large equipment, such as industrial robots. In addition, it is not easy to perform high-quality welding, because tracing a welding line accurately at a constant speed requires a long training period. In this research, the aim was to develop a welding assist device that can be applied to a welding environment. The proposed device fixes to the welding surface by magnetic force and assists semiautomatic welding with a magnetorheological (MR) brake. MR brakes have a sufficient response speed compared with powder brakes, have a large output weight ratio, and are considered to be suitable for welding assistance. In this work, a strategy for control of path rendering and speed restriction by MR brakes is proposed. Its effectiveness was confirmed by experiments with a prototype.