Improved Multi-Step Look-Ahead Control Policies for Automated Manufacturing Systems

The deadlock control problem in automated manufacturing systems (AMSs) has received much attention in recent years due to the flexibility of an AMS. In the framework of Petri nets, resource-transition circuits and siphons are often used to characterize and derive a deadlock control policy for an AMS. This paper mainly focuses on a class of Petri nets, namely, the system of simple sequential processes with resources, which contains some special resource places. For such a class of Petri nets, the relationship between a multi-step look-ahead deadlock avoidance control method and the structure of the model is established and expanded in a mathematical way. Unlike the one-step look-ahead deadlock avoidance policy (DAP) proposed in the literature, the DAPs reported in this research are applicable to more complex situations, including a model with one-unit resource shared by two or more perfect resource-transition circuits that do not contain each other. Compared with the existing work, some results are archived for expanded models. Finally, for the model with two shared one-unit resources, specific solutions are also presented. Meanwhile, examples are used to demonstrate the proposed results.