Fuzzy priority rule for job shop scheduling

Abstract

Job shop scheduling uses various kinds of priority rules such as SPT, CR, COVERT, etc. Each of these rules aims at satisfying a single criterion though scheduling is a multi criteria problem. In this paper, a new approach using fuzzy logic is introduced to combine SPT, CR priority rules, and next machine's load (NML) rate the job to be processed next in order to satisfy not only a single objective but also all objectives. Fuzzy logic calculates priority value by considering SPT, CR, and NML. We named this priority rule as fuzzy priority rule (FPR). The job with the highest priority value is assigned to machine to be processed. To compare FPR with other priority rules such as SPT, EDD, etc. we run simulation. The results indicate significant improvements on mean flow time, mean tardiness, work in process (WIP), and throughput simultaneously.