Distributed event-control for deadlock avoidance in automated manufacturing systems

This paper develops a decentralized event-control strategy to avoid deadlock in automated manufacturing systems. On the basis of the characteristics of the part mix that is currently active, the system is partitioned in subsystems that can be controlled locally and independently using graph-theoretic tools. The controller of each subsystem can be chosen as the best compromise between computational costs and flexibility in resource allocation and depending on the particular layout of the subsystem. The decentralized scheme allows the overall system to improve its flexibility and guarantee good performance measures. The approach is particularly suitable for cellular manufacturing systems that do not exclude intercell flow. In this case the method 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.