Minimizing total travel time in the flexible job-shop scheduling problem with transportation resources
研究了在柔性作业车间调度中同时优化制造周期和运输车辆总旅行时间的问题，提出了新的邻域结构和精确评估方法，并通过实验验证了工厂布局和车辆数量的影响。
Time-dependent manufacturing criteria, such as makespan or mean flow time, are commonly optimized in scheduling problems. Prioritizing these criteria is motivated by their correlation with key performance indicators, such as throughput and cycle time in flexible manufacturing systems. However, when transportation resources must also be explicitly managed, only optimizing manufacturing criteria may result in very poor schedules in terms of the distance traveled by the vehicles. This research aims to simultaneously optimize the makespan and the distance traveled by the vehicles, called total travel time, in the flexible job-shop scheduling problem with transportation resources. New generic neighborhood structures are proposed as well as an exact constant-time evaluation of the neighbor solutions in terms of total travel time. These findings are then used to introduce several optimization approaches in order to determine schedules that optimize both the makespan and the total travel time. The proposed approaches are experimentally tested on benchmark instances, and the numerical results are discussed, in particular the impact of the factory layout and the number of vehicles.