Integrated approach for multi-robot spot-welding cell design and welding-point allocation

The design of multi-robot cells for spot welding strictly influences the feasibility and complexity of the multi-robot motion planning. In comparison to existing literature, the proposed approach simultaneously addresses: (i) the design of multi-robot cells for spot welding; (ii) the allocation of the welding points to the robots on the basis of required cell cycle time. First, the algorithm selects one robot model and one robot fixturing structure. Second, the approach identifies free trajectories among welding points for each couple gun/position of the robot in the fixturing structure through probabilistic roadmaps (PRMs). Third, on the basis of the previous results, an innovative mathematical model selects and allocates the resources taking into account cell investment costs. Finally, the solutions that differ on robot model and robot fixturing structure are compared and the best solution is selected. A test case is provided to show the applicability of the approach.