Design of Robust Optimization Petri Net Controller for Automated Manufacturing Systems With Unreliable Resources

This paper develops a robust deadlock control method for automated manufacturing systems (AMSs) with unreliable resources. The considered AMS is modeled by a generalized system of simple sequential processes with resources (GS(3)PR). The notion of improved recovery subnets is developed to model a resource failure scenario where if a failure occurs, the damaged resource is removed for repair and the part is returned to the system for the subsequent production. Based on a reachability graph partition technique that can compute all forbidden markings and robust legal ones, an invariant-based robust supervisory control strategy is developed to guarantee the former reachable and the latter unreachable. It is verified that the designed robust controller can assure the liveness of the controlled system regardless of whether resource failures occur. Finally, we present two examples to show the validity of the proposed method.