Robust deadlock control for automated manufacturing systems with an unreliable resource

So far, most of deadlock control policies are proposed based on the assumption that automated manufacturing systems (AMSs) have no unreliable resources. While in real manufacturing systems, resource failure is inevitable and will reduce the number of available resources. This paper focuses on the robust deadlock control problem for AMSs with an unreliable resource. Petri nets are used to model the unreliable systems, and a subclass of the ordinary and conservative Petri nets, known as system of simple sequential process with resources (S3PR), is studied. A resource failure and recovery net is added to describe the resource failure and recovery. To prevent each siphon from being emptied, the concept of constraint set for a strict minimal siphon is introduced. By limiting the number of tokens in each constraint set, a robust deadlock controller is devised. It is proved that our controller can guarantee the liveness of the controlled system no matter one resource fails or not. Finally, some examples are provided to illustrate the validity of the proposed robust deadlock controller.