Distributed event-control for deadlock avoidance in automated manufacturing systems

This paper develops a decentralized event-control strategy to avoid deadloc k in automated manufacturing systems. On the basis of the characteristics o f the part mix that is currently active, the system is partitioned in subsy stems that can be controlled locally and independently using graph-theoreti c tools. The controller of each subsystem can be chosen as the best comprom ise between computational costs and flexibility in resource allocation and depending on the particular layout of the subsystem. The decentralized sche me allows the overall system to improve its flexibility and guarantee good performance measures. The approach is particularly suitable for cellular ma nufacturing systems that do not exclude intercell flow. In this case the me thod determines the cells that can be controlled independently and the ones that must be controlled jointly. A case study performed by discrete-event simulation confirms the efficiency of the proposed methodology.