Optimal pass planning for robotic welding of large-dimension joints with nonuniform grooves

Large-dimension welded joints are widely used in shipyards and oilfields. These joints typically have thick and nonuniform welding grooves, thus requiring multi-pass welding processes and tens of hours to complete. Although the development of robotic welding systems can shorten the welding time, it is important to have a detailed plan of the entire process before welding starts. Welding pass planning is crucial for the subsequent robot trajectory generation and provides the welding sequence in a deep groove and the welding parameters of every pass. A knowledge database is used in this research to obtain the relationship between the bead geometry and the welding parameters. A layer-by-layer welding pass planning scheme is proposed to address the nonuniform groove geometry, and an optimization method is proposed with the objective to maximize the section area of the weld bead, so that the number of passes can be minimized. The planning results show that the optimization method is able to provide feasible passes and welding parameters for every pass.