Optimally Robust Control for Automated Manufacturing Systems With an Unreliable Resource Using Resource-Oriented Petri Nets

In automated manufacturing systems (AMSs), researchers have studies many robust deadlock control policies. Nevertheless, few methods achieve maximally permissive control of robustness. In this paper, therefore, for AMSs with an unreliable resource, an optimally robust deadlock supervisor is devised on the basis of resource-oriented Petri nets (ROPNs). By analyzing the structural characteristic of an ROPN, deadlock and blocking states are found in a special PN structure. We show that only the partial bad states are controlled, the system can realize robust deadlock-free control. The method is to allocate buffer space of resources such that the breakdown of an unreliable resource cannot prohibit parts in production routes not using the failed resource. Examples are finally given to illustrate the policy.