Efficient Assessment of State Liveness in Open, Irreversible, Dynamically Routed, Zone-Controlled Guidepath-based Transport Systems: The General Case

Open, irreversible, dynamically routed, zone-controlled guidepath-based transport systems model the operation of many automated unit-load material handling systems that are used in various production and distribution facilities. An important requirement for these systems is to preserve the system liveness-i.e., the ability of each system agent to reach any location of the underlying guidepath network-by blocking those traffic states that will result in deadlock and/or livelock. The remaining set of traffic states are characterized as "live". The worst-case computational complexity of the decision problem of assessing the state liveness in the considered class of transport systems is an open issue. This work capitalizes upon some recent developments on the problem of assessing state liveness in the considered transport systems in order to provide a novel algorithm for this problem. The worst-case computational complexity of this algorithm is not polynomially bounded with respect to the size of the underlying transport system, but the empirical complexity of the algorithm is expected to be very benign for the reasons that are explained in the paper. Copyright (c) The Authors. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0)