A simulation modeling framework for multiple-aisle automated storage and retrieval systems

This paper presents a simulation model framework for unit-load automated storage and retrieval systems (AS/RS) able to cope with most of the features found in industrial settings like, for example, multiple aisles, non aisle-captive cranes or double-deep unit-load AS/RS. Although these features characterize most of the industrial applications, they have been simply neglected by most of the previously published research oriented papers, which explains at least partially the low impact of the research output in practice. To help mitigating this drawback, this paper first presents an up-to-date chronological literature survey, which includes works that use any form of simulation in the modeling process. It then proposes an Object-Oriented Simulation Model for unit-load AS/RS developed with a purely generic mindset. In this model, the physical design decisions are separated from the operational decisions, which makes it possible, first, to obtain a better understanding of AS/RS dynamics and, second, to increase the model's flexibility and generality, thus allowing many interesting scenarios to be represented. In particular, the simulation modeling framework has been used to develop a simulator and to conduct a preliminary study on a multi-aisle AS/RS.