Job Shop Scheduling Focusing on Role of Buffers (2nd Report, Feasibility Judgement by Utilizing Graph)

Abstract

A scheduling problem is formulated focusing on jobs stored in production resources in the present paper. In a production system with finite buffer capacity, the job are stored in not only buffers but also production resources such as machine tools and assembly robots. Therefore, successive jobs cannot be processed by the resources until the previous jobs are removed from them. In such a scheduling problem, certain processing orders of jobs are infeasible because start times and release times of the jobs can not be determined. The graph representation method for conventional scheduling problems is extended in order to judge feasibility of the present schedules, in which the jobs stored in the resources are taken into account. A local searching method is applied to improve the schedules of the production systems with finite buffer capacity. It gives an appropriate schedule in combination with the dispatching procedure proposed in the first report.