A Hybrid Multiobjective Evolutionary Approach for Flexible Job‐Shop Scheduling Problems

Abstract

This paper addresses multiobjective flexible job‐shop scheduling problem (FJSP) with three simultaneously considered objectives: minimizing makespan, minimizing total workload, and minimizing maximal workload. A hybrid multiobjective evolutionary approach (H‐MOEA) is developed to solve the problem. According to the characteristic of FJSP, a modified crowding distance measure is introduced to maintain the diversity of individuals. In the proposed H‐MOEA, well‐designed chromosome representation and genetic operators are developed for FJSP. Moreover, a local search procedure based on critical path theory is incorporated in H‐MOEA to improve the convergence ability of the algorithm. Experiment results on several well‐known benchmark instances demonstrate the efficiency and stability of the proposed algorithm. The comparison with other recently published approaches validates that H‐MOEA can obtain Pareto‐optimal solutions with better quality and/or diversity.