Title: A generalised sequencing problem for unit-load automated storage and retrieval systems
Author: Eunyong Chung, H. Felix Lee
Department of Global Business, DongHae University, DonghaeSi, KangwonDo 240–713, South Korea.
Industrial and Manufacturing Engineering, Southern Illinois University, Edwardsville, IL 62026–1805, USA
Abstract: With continuing need for high throughput Automated Storage and Retrieval Systems (AS/RS), many researchers have studied a problem of sequencing storage and retrieval requests processed by the storage/retrieval machine to maximise the system throughput. These studies assume that each retrieval request is fixed with a pre-determined bin position in the AS/RS rack. However, in reality, a retrieval request is associated with a specific product item which is available in multiple bin locations. In this paper, we address a generalised sequencing problem that determines both specific bin locations for the retrieval requests and sequencing with the chosen bin locations. To solve this new complex combinatorial problem, we introduce heuristic methods and present their computational results. We also present the analytical cycle time distribution and mean value for the single command when an item of a retrieval request is available in multiple bin locations.
Keywords: automated storage; automated retrieval; AS/RS; retrieval sequencing; retrieval sets; throughput; travel time model.
Int. J. of Industrial and Systems Engineering, 2007 Vol.2, No.4, pp.393 - 412
Available online: 11 Apr 2007