Performance of deadlock avoidance algorithms in flexible manufacturing systems

Deadlock is a highly unfavorable situation that can occur in flexible manufacturing systems. The occurrence of a deadlock can cripple parts of a production system and hinder flexible automation. It is necessary to develop control policies that avoid deadlocks by restricting the freedom in resource allocation; however, such policies can also negatively affect system performance indices. Feedback algorithms, which use information on the current operating condition of the system to avoid deadlock, can be distinguished based on the effects of the constraints they impose on the freedom in resource allocation. Referring to this characterization of the algorithms, this paper compares performances of some deadlock avoidance policies. First, theoretical analysis is carried out by introducing a criterion for ordering different policies by flexibility in resource allocation. Second, avoidance policies are applied to some case studies, which are simulated in details. The simulation analysis confirms the theoretical results showing that the algorithms allowing larger flexibility in resource allocation lead to better performance indices.