Hierarchical Crossover-Based NSGA-III for Dynamic Flexible Job Shop Scheduling Problem

The flexible job shop scheduling problem (FJSP) is a common production scheduling issue in manufacturing, aiming to optimize multiple objectives during the production process while satisfying production constraints. However, in actual production environments, machine breakdowns are frequent dynamic factors that can cause job interruptions and production delays, thereby affecting the effectiveness of scheduling optimizations. To address this issue, this paper proposes a hierarchical crossover-based NSGA-III (HCNSGA-III). Firstly, we design a hierarchical crossover strategy that stratifies the Pareto front, applying different crossover strategies for different levels. Secondly, we design a dynamic reference point update method that dynamically adjusts the reference points based on the current population's solution set, enhancing adaptability to the problem. Finally, comparative analysis with other algorithms demonstrates that the proposed method exhibits good performance in solving dynamic scheduling problems caused by machine breakdowns.