Reconfiguration Control of Dynamic Reconfigurable Discrete Event Systems Based on NCESs

Abstract

In order to satisfy system specifications persistently in the cases of component failure, partial communication blocks, or energy deficiency, safety-critical systems need to apply system reconfigurations at runtime. Such systems can be considered as dynamic reconfigurable discrete event systems (DRDESs) if their logic behaviors are concerned only. A reconfiguration of a DRDES includes the switch of system structures and the update of system states. Based on the assumption that all configurations of a DRDES are designed in advance and dynamic reconfigurations can be implemented only at a few predefined reconfigurable states, a novel reconfiguration control method is proposed in this paper. The aim is to implement a required dynamic reconfiguration smoothly and rapidly. A DRDES is modeled by net condition/event systems (NCESs) under the firing rule “maximal single spontaneous transition steps.” An integer linear programming-based method is developed to compute a shortest legal firing sequence (SLFS) from the state where a reconfiguration requirement arises to a reconfigurable state. Accordingly, a virtual controller for guiding the system to evolve along the obtained SLFS is proposed. The proposed method is able to implement a required reconfiguration before the maximum permissible reconfiguration delay if an SLFS exists. A simple reconfigurable assembly system is adopted to illustrate the method.