Behavior control methodology for circulating robots in flexible batch manufacturing systems experiencing bottlenecks

This paper focuses on an automated batch manufacturing system with material-handling robots (MHRs) and material-processing robots (MPRs). In this robotic manufacturing system, materials transported by the MHRs are processed by the MPRs. These operations cause a bottleneck in the system. Furthermore, the bottleneck induces congestion of the MHRs. In the system, the effect of an operational delay due to bottlenecks affects the entire operation. Accordingly, there is an event in which the congestion extends and the system throughput not only fails to increase but also may become worse, even if more robots are used to improve the productivity. For this challenge, we propose a behavior control method for the MHRs to eliminate or ease the congestion that arises from a bottleneck. Each MHR controls its own behavior adequately by using the external force of a virtual damper in order not to become involved in the congestion. Finally, through a simulation experiment, we show that the proposed control method improves the system throughput and its effectiveness for a more efficient system operation.