PRIAM: polite rescheduler for intelligent automated manufacturing

This paper considers the problem of rescheduling in a decentralized manufacturing system. Flexible manufacturing systems must be able to respond to unexpected disruptions; including schedule disruptions. However, when a cell controller in a decentralized system responds to a disruption, it may disrupt some other cells, because the actions taken at one cell may have some consequence at another cells. In the approach we propose, a controller at a disrupted cell tries to respond in a way which is likely to be least disruptive to other cells, through negotiation with controllers at other cells. This approach, which we call "polite replanning", has the advantage of retaining much of the original distributed plan, while avoiding wide propagation of the disruption through the rest of the system. We apply this concept to the domain of distributed factory rescheduling, and describe PRIAM (polite rescheduler for intelligent automated manufacturing), a "polite" rescheduling architecture which is currently under development. Simulation results show that the use of negotiation in "polite" rescheduling prevents the wide propagation of disruption from an initial local disruption.