Accommodating FMS operational contingencies through routing flexibility

Overwhelmed by the complexity of the FMS deadlock avoidance problem, current research has essentially ignored the aspects (and benefits) related to flexible (dynamic) job routing. Furthermore, extending the currently existing results along this line is nontrivial, primarily because of the fact that the possible routing options for a single job can grow exponentially fast. Hence, computationally efficient techniques are required to incorporate the inherent FMS routing flexibilty into current structural control schemes. The paper initiates the investigation on the problem of integrating routing flexibility in FMS structural control, by addressing the problem of "optimal" job re-routing in the case of operational contingencies. An analytical problem formulation and an efficient solution algorithm are developed for the case that the FMS is structurally controlled by the resource upstream neighborhood (RUN) policy, a deadlock avoidance policy previously presented in the literature. Beyond the value of the presented results, the paper is intended also to outline a methodological approach to the underlying problems.