2000 Volume 26 Issue 5 Pages 661-668
An autonomous decentralized scheduling system, which aims at minimizing the sum of changeover cost, storage cost, and due-date penalty, is proposed for flowshop problems. In the proposed system, the scheduling system belonging to each production stage gradually generates a plausible schedule through repeated generation of schedules for the stage and repeated exchange of data among the production stages. When intermediate storage cost is included in the objective function, calculation of the optimal starting times of jobs is fairly difficult, even if the production sequence of jobs at each stage is fixed. In this study, an algorithm for effective calculation of the starting times of jobs, which can minimize the storage cost, has been developed. By embedding this algorithm in the scheduling algorithm, an autonomous decentralized scheduling system, which realizes Just-in-Time production at all production stages, is developed. It is also shown that the proposed system is applicable to the case in which the space available for intermediate storage is limited. The results of example problems show that the schedules obtained by the proposed system are significantly better than those obtained by conventional methods.
