A Graph Theoretic Method to Handle Deadlocks in Flexible Manufacturing Cells

The deadlock-handling scheme is based on a bipartite graph model of the part-machine relationship in the manufac- turing cell.A distinction is made between permanent deadlock and transient deadlock.Permanent deadlock depicts a manufactur- ing system state where parts are irrevocably blocked and where external intervention is required to resolve the deadlock,whereas a transient deadlock indicates that there is a positive probability that the deadlock will resolve itself over time.To recover from dead- locks,one control policy is studied:resolve deadlocks in the manufacturing cell.Under the policy,it is shown that it is sufficient to resolve any cycle in the set of deadlocked parts to resolve the deadlock.Finally,we estimate the deadlocks in flexible manufactur- ing cells.