Abstract
Deadlock problems in highly automated manufacturing system (AMS) have recently received considerable interest from both industry and academia. In most of the researches, structural analysis and reachability graph analysis have been used to develop deadlocks prevention policies for AMSs based on ordinary petri nets. These policies are considered for deadlock problems in AMS with shared and reliable resources, while AMS are timed and subjected on unreliable resources. To provide a solution for this circumstances, this research developed appropriate methods for designing controller and analyzing of AMSs with shared and unreliable resources taking into account deadlocks problems. The proposed controllers enable systems to be worked with improved performance and high resource utilization based on timed petri nets. In this research a case study is provided to demonstrate the usefulness of the deadlock-control algorithm to ensure no occurrence of deadlocks in AMS. The flexible manufacturing system has been modelled using Visual Object Net version 2.a software and the simulation is done for 26 days (8 h per day). A performance comparison between two developed policies, failures causing scrapping and process resumes subsequent to repair, is made. Moreover, some issues are recommended to select the best policy.