Bi-objective optimization for a two-depot automated storage/retrieval system

Operation management of automated storage and retrieval system (AS/RS) has a great impact on system performance and is a hot research topic. Most existing works for AS/RS operation management address determining storage and retrieval (S/R) machine sequence and minimizing its travel time. In the paper, we study a new bi-objective S/R machine sequencing problem with task release time and due date in a two-depot AS/RS. The objective is to minimize the total travel time of the S/R machine and the total tardiness simultaneously. For the problem, a new bi-objective mixed integer linear programming model is established. Based on problem property analysis, an exact ϵ-constraint method, a non-dominated sorting genetic algorithm II and a promising heuristic are devised for the problem. Especially, the computational results show the efficiency and effectiveness of the proposed algorithms.