Storage-Retrieval Interleaving in Automatic Warehousing Systems

This paper extends work previously reported on storage assignment rules for automatic warehousing systems to include interleaving; that is, the sequencing of storage and retrieve requests. Using both continuous analytical models and discrete evaluation procedures, this paper compares the operating performance of several storage assignment/interleaving policies. The results indicate that significant reductions in crane travel time (and distance) are obtainable in some real-world and/or previously modeled situations via the proposed storage assignment/interleaving policies. These reductions may be directly translated into increased throughput capacity for existing systems. The storage assignment/interleaving policies may also be used to improve the design of proposed systems to achieve a more desirable balance between throughput and storage capacity. Although the system examined is a high-rise automatic warehouse, the results presented have implications for the warehousing function in general.