Production scheduling and inventory control for multi-stage manufacturing systems

In this paper, singular perturbation methods are used to synthesize high-gain error-actuated production control policies for a class of multi-stage manufacturing systems in which each manufacturing sub-system comprises either one or several production facilities. It is shown that when the manufacturing sub-systems are connected in cascade, each sub-system can be controlled in isolation, but that production control policies based on this approach lead to undesirable transient behaviour if the value of the feedback gain parameter is small. An alternative approach whereby production control policies are synthesized for the composite system leads to improved transient behaviour. However, if the value of the feedback gain parameter is large, both approaches are shown to yield good transient behaviour. In addition, it is demonstrated that trade-off between rapid adjustments in production rates and large inventory-level deviation can be achieved by selecting an appropriate value for the feedback gain parameter.