Combined Petri net modelling and AI-based heuristic hybrid search for flexible manufacturing systemsラpart II. Heuristic hybrid search

This two-part paper presents modelling and scheduling approaches of flexible manufacturing systems using Petri nets (PNs) and artificial intelligence (AI)-based heuristic search methods. In Part I, PN-based modelling approaches and basic AI-based heuristic search algorithms were presented. In Part II, a new heuristic function that exploits PN information is proposed. Heuristic information obtained from the PN model is used to dramatically reduce the search space. This heuristic is derived from a new concept, the resource cost reachability matrix, which builds on the propertiesofB-netsproposed inPart I.Twohybrid searchalgorithms, (1)anapproach tomodeldispatchingrulesusing analysis information provided by the PN simulation and (2) an approach of the modified stage-search algorithm, are proposed to reduce the complexity of large systems. A random problem generator is developed to test the proposed methods. The experimental results show promising results. q 2002 Elsevier Science Ltd. All rights reserved.