A 2-LEVEL HIERARCHICAL APPROACH FOR RAW-MATERIAL SCHEDULING IN STEELWORKS

Raw material scheduling problems in steelworks suffer from the computa tional complexity arising from the interdependence and interference be tween various items of transport equipment To deal effectively with su ch complexity, this paper proposes a two-level hierarchical architectu re for the construction of predictive schedules to transport raw mater ials from stock yards to processing plants. The architecture allocates the raw materials required, to multiple lower-level dispatchers, each of which schedules its reclaimer to withdraw the assigned raw materia ls. A higher-level scheduler constructs belt-conveyor schedules for tr ansporting the reclaimed raw materials to their processing plants. If any conflict occurs within a dispatcher during the scheduling process, the higher-level scheduler coordinates other dispatchers for conflict resolution. Based on this architecture, a scheduling expert system ca lled RAMS was developed using G2, to automate the raw material schedul ing process at a steelworks. By providing the predictive raw material transport schedule, the system is proved to relieve the burden on the human scheduler and to improve schedule performances. (C) 1997 Publish ed by Elsevier Science Ltd. All rights reserved.