A Petri-Net Based Hierarchical Structure for Dynamic Scheduler of an FMS: Rescheduling and Deadlock Avoidance

Flexible manufacturing sys tems ( F M S s ) have received considerable at tent ion and evolve to be one of the fastest growing industrial field in the last decade. In these sys tems , m u c h higher e f i c i e n c y of manufacturing can be achieved (owning to their intr insic f lexibility) provided a good scheduling policy i s adopted. In this paper, w e propose a dynamic scheduler wi th a hierarchical structure t o cope with the unavoidable disturbing events in such dynamic sys tems like a n F M S . In particular, we based o n our earlier work [6] handle the rescheduling problem as we as the deadlock avoidance problem. T h e mer i t of this work i s i t s completeness in considering all possible components in a n F M S, including A G V transportat ion sys tem.