Optimization of transporting time through load shuffling in automated storage and retrieval system and evaluation via demonstration experiments

Abstract An automated storage and retrieval system (AS/RS) is a system that automates storing and retrieving raw materials and products in factories and distribution centers. The storage/retrieval machines (S/R machines) can automatically transport loads without human labor. In this paper, we focus on “load shuffling,” which is changing the storage location of the load once it is stored in the AS/RS. In the proposed method, load shuffling is formulated to minimize the transporting time by S/R machines as a relocation problem of loads in the AS/RS, using a 0–1 integer programming problem. By solving this problem and reallocating the loads, we aim to reduce the time spent transporting loads during the production process in factory operations. Two types of numerical experiments were conducted: one using simulation and the other using an actual factory. Simulation experiments confirmed that using load shuffling reduced the time transporting loads. The demonstration experiment using an actual factory confirmed that load shuffling reduces the time required for the machine to transport loads despite the restrictions imposed by actual production activities.