PARTIAL CHARACTERIZATION OF OPTIMAL HEDGING POINT POLICIES IN UNRELIABLE 2-PART-TYPE MANUFACTURING SYSTEMS

The production control problem in unreliable manufacturing systems has generated a great deal of interest recently. The goal is the real-tim e calculation of production rates to minimize total expected surplus a nd backlog costs in a production system. A class of feedback control p olicies, called hedging point policies, has been studied in literature and shown to be optimal for certain single-part-type systems. This pa per focuses mainly on the performance of hedging point policies in two -part-type systems. We first generalize known stability results for he dging point policies in single-part-type systems and extend them to tw o-part-type systems. An average cost analysis of trajectories is then used to partially characterize an optimal policy belonging to this cla ss. A complete characterization is obtained for special parameter valu es. The results in this paper provide insights for designing simple ye t effective heuristics for controlling manufacturing systems producing many part-types.