Meta-heuristics for Solving a Bi-Objective Hybrid Flexible Flowshop Scheduling Problem

In this paper, the problem of scheduling a hybrid flexible flowshop with two objective function, which is to minimize the total costs of earliness and tardiness tasks and maximize the quality of the work, have been studied. Since the objectives of the problems are contradictory, the problem does not have a definite solution, but it has a set of solution. Due to the complexity of the problem, the multi-objective optimization algorithms namely NSGA-II and SPEA-II have been developed to solve the problem. The Taguchi method has been used to set the parameter of the proposed algorithms. Also, a set of numerical problems, including 15 examples in different dimensions, was presented and the efficiency of the algorithms was evaluated with respect to functional indicators. According to the obtained results, the SPEA-II has achieved a shorter response time. In the case of other indicators, the performance of the two algorithms was very close, but the NSGA-II performed slightly better.