| Abstract: | In recent years, deadlock issue has received considerable attention in the real-time control realm of automated manufacturing system (AMS). In this paper, we propose a simple and easily adaptable deadlock avoidance algorithm using a graph theoretic approach. Unlike Petri-net based methods which are complex and static from the viewpoint that once they are constructed and implemented, it is not easy to modify them as the system configuration is changed, and operate them coupled with other shop-floor control modules such as a dispatching controller, our algorithm can be used cooperatively with a dispatching controller and expanded with little modification. The core of the algorithm consists of two modules: resource allocation policy and a cycle detection method. In particular, the resource allocation policy is of importance in our algorithm because even though the cycle detection method is employed, deadlock may occur under wrong resource allocation policies. Throughout this paper, we propose a quasi two-step resourceallocation policy with which our deadlock avoidance algorithm can detect and avoid deadlock just one step before deadlock. |
