Scheduling and worker assignment problems on hybrid flowshop with cost-related objective function

Abstract

This paper proposes a colonial competitive algorithm which is improved by variable neighborhood search algorithm for the simultaneous effects of learning and deterioration on hybrid flowshop scheduling with sequence-dependent setup times. By the effects of learning and deterioration, the processing time of a job is determined by position in the sequence and its execution start time. In addition, it is assumed that the processing time of any job depends on the number of workers assigned to the job on a particular stage, and the more workers assigned to a stage, the shorter the job processing time. These additional traits that are added to the scheduling problem coexist in many realistic scheduling situations. This problem consists of two basic questions of job scheduling and worker assignment. Minimization of the earliness, tardiness, makespan, and total worker employing costs is considered as the objective function. To evaluate the performance of the hybrid colonial competitive algorithm, the random key genetic algorithm, immune algorithm, variable neighborhood search, and hybrid simulated annealing metaheuristic presented previously are investigated for comparison purposes, and computational experiments are performed on standard test problems. Results show that our proposed algorithm performs better than the other algorithms for various test problems.