Abstract: Because of the reverse operation of the double-deep four-way shuttle warehouse, the efficiency of the outbound operation is reduced. The mathematical model of the process of outbound and inbound was established. A strategy for selecting the location of reverse and a strategy for selecting the location of back were proposed in which the influence of the current operation on the subsequent outbound was considered. A task sequence optimization algorithm was proposed to minimize the task time. An improved genetic algorithm was used. By using the Kendall coefficient to initialize the population, the spatial search ability of the algorithm was enhanced. The characteristics of the double-deep warehouse was taken into account, and then a gene order change process was introduced into the genetic algorithm to improve its convergence speed. The results of simulation experiment show that the proposed strategy can significantly improve the efficiency of outbound operation. At the same time, the improved genetic algorithm has faster convergence speed, better optimization effect and higher stability, which can effectively shorten the outbound operation time and improve the outbound operation efficiency.

Key words: double-deep system, task scheduling, four-way shuttle-based storage and retrieval system