Strong Controllable Siphon Basis-Based Robust Deadlock Control for Manufacturing Systems With Multiple Unreliable Resources

In real-world automated manufacturing systems (AMSs), a breakdown of unreliable resources in operation often makes most existing deadlock control policies inapplicable. This work focuses on robust deadlock control problem in AMSs with multi-type and multi-unit unreliable resources. The unreliable resource's failure and repair activities are modeled by Petri nets. We introduce a concept of strong controllable siphon basis, which can be seen as an extension of the controllable siphon basis proposed in our previous work. Then by adding a control place with proper depth variable to each strict minimal siphon (SMS) and R-type SMS in a strong controllable siphon basis, we successfully develop a small-scaled robust deadlock controller for AMSs under consideration. Such a robust controller can guarantee that, as long as at least one unit of each unreliable resource type is available, all types of parts can be processed smoothly through any one of their routes even during downtime. Moreover, the number of control places of the proposed controller is no more than that of the activity places in the Petri net model and its size grows polynomially with Petri net model.