Multirobot Coordination for Flexible Batch Manufacturing Systems Experiencing Bottlenecks

In this paper, we focus on a batch manufacturing system with multiple industrial robots. In this system, material-handling robots (MHRs) and material-processing robots (MPRs) are operating. Since various operations are conducted at certain places, one of them might include a localized bottleneck. A localized bottleneck is a constraint that dominates the maximum amount of production in a system, that is, the productivity. In addition, the bottleneck induces congestion; as a result, the productivity declines. For these issues, there are two primary challenges: bottleneck prevention and restraint. To solve them, suitable operational techniques with respect to the MHRs and MPRs are needed in order for them to operate appropriately while relating to each other. In this paper, a constructive approach toward multi-robot coordination problems is taken. In this approach, we propose applicable operational techniques for the robots. Through simulation experiments, we examine the effectiveness of the proposed techniques and their combinations and, finally, show an integrated operational technique. Each of the operational techniques solves a localized bottleneck and the congestion, and the integrated technique successfully improves the productivity and results in the most efficient system.