Exact and Heuristic Approaches for the Design of Automated Storage and Retrieval Systems (AS/RS)

This paper deals with the optimization of the design of automated storage and retrieval systems (AS/RS). What is meant by design's optimization is to determine the dimensions (height, length and depth) of a system for a given size that minimize its average retrieval time. The considered system is the bidirectional flow-rack AS/RS. Discrete and continuous models of retrieval times for this system are used to conduct this investigation. Discrete models are most faithful to the system behavior, while continuous ones are based on a couple of approximations. We propose in this paper an exact and heuristic approach to optimize the design of the studied bidirectional flow-rack AS/RS. The exact approach is based on the discrete models whereas the heuristic approach is based on a rounding technique of the continuous models. We compare both approaches against each other. Results show the proposed heuristic reaches competitive results with optimality reached for some system sizes.