Bi-objective energy-efficient scheduling in a seru production system considering reconfiguration of serus

Owing to movable workstations, light equipment and multi-skilled workers, serus can be constructed, modified and dismantled rapidly. Such an advantage enables serus to be reconfigured in response to frequent changes in product types. As different configurations lead to different processing time and energy consumption, an important issue is how to arrange a best configuration of seru with the tasks assigned to it. To this end, we focus on solving the task dispatching, product sequencing and seru reconfiguration problems simultaneously considering economic and environmental performance. A bi-objective mathematical model with objectives of minimizing the total earliness and tardiness and the total carbon dioxide emission is formulated. The problem is proved to be strongly NP-hard, and a non-dominated sorting genetic algorithm-II (NSGA-II) is developed. The algorithm is tested by a medium-size numerical example and ninety sets of large-size problems. Based on the computational results, the impact of configuration flexibility and the relation between processing time and energy consumption on the value of objective functions is analyzed.