Hierarchical flow control: a framework for scheduling and planning discrete events in manufacturing systems

The synthesis of operating policies for manufacturing systems is discussed. These are feedback laws that respond to potentially disruptive events. Laws are developed that are based on realistic dynamic programming models that account for the discrete nature of manufacturing and are computationally tractable. These scheduling and planning policies have a hierarchical structure which is systematically based on the production process. The levels of the hierarchy correspond to classes of events that occur with distinct frequencies. At each level, feedback laws select times for the controllable events whose frequency class is treated at that level and frequency targets for much higher-frequency controllable events