AN OPTIMAL-CONTROL MODEL FOR CONTINUOUS-TIME PRODUCTION AND SETUP SCHEDULING

This paper concerns a new approach to continuous time optimal scheduli ng problems for a large class of manufacturing systems. The proposed a pproach states the problem in terms of optimal control with setup and production rates controllable on one hierarchical level. This allows f or the traditional disadvantages of the two-level problem consideratio n (one level for defining the target production rates, and the other f or scheduling the setup changes) to be avoided and stable control stra tegies to be obtained. Analysis of the maximum principle results in se tup conditions of the optimal schedule and special regimes to which th e optimal tends between subsequent setups. Based on these results, a n umerical method is developed to define the sequence of the special reg imes and the timing for getting into and out of them. An example illus trates the effectiveness of the approach.