Storage Systems with Virtual Aisles

Auburn University, Auburn AL

Investigators

Abstract

In automated and traditional manual warehouses, there is a classic tradeoff between the storage density of the system (items per square or cubic foot) and the throughput of that system (items retrieved per unit time). The more dense the storage, the lower the throughput. This research proposes a new storage system design which could provide both very high storage density and very high throughput, using a concept called "virtual aisles." A conceptual model for this system will be developed, including a decentralized control algorithm that manages the simultaneous retrieval of multiple items. A second algorithm will integrate replenishment of items, allowing the system to operate in steady-state. Multiple objectives will be explored, including controlling the system to maximize throughput and controlling it to minimize energy consumed. The second phase of the research explores the allocation of free, or empty, space within the storage system, in a way that minimizes the expected time to retrieve an item. The final phase will develop control algorithms to permit insertion and extraction of items from all four sides, making, in three dimensions, a sort of "living cube," which allows items to pass in and out upon command. If the proposed control algorithms provide the promised benefits in terms of throughput and storage density, systems that use them could significantly reduce the footprint of internal storage in factories and warehouses of any industry using automated material handling technology. These algorithms would be part of storage systems with decentralized control, which could allow for more flexible and robust material handling in modern manufacturing and distribution. The analytical methods employed in this research (statistical analysis of cellular automata) will also lead to the development of new tools for material handling systems analysis and design.