Reconciling High-Speed Scheduling with Dispatching in Wafer Fabs

A novel approach to reconciling global optimizing scheduling with real-time dispatching is presented. High speed scheduling is accomplished by two simultaneous cooperating scheduling processes, one of which generates longer term schedules while the other is focused with higher resolution on the nearer term. Real-time dispatching is based on the most recently generated near term schedule, carefully reconciled with events that could affect its current validity on the shop floor. Results are presented which show a fivefold performance speedup in schedule generation time, as well as significant schedule quality improvements over pure dispatching approaches.