自动化立体仓库(英文)

关于自动化立体仓库使用双货叉问题的探讨-An Analysis Of Dual Shuttle Automated Storage/Retrieval Systems

An Analysis Of Dual Shuttle

Automated Storage/Retrieval Systems

Adhinarayan Keserla

Brett A. Peters

August 1, 1994

This working paper is not to be copied, quoted, or cited without the permission of the authors. Address correspondence to Brett A. Peters, Dept. of Industrial Engineering, Texas A&M University, College Station, TX 77843-3131 or email to bpeters@

Abstract

This paper addresses the throughput improvement possible with the use of a dual shuttle automated storage and retrieval system. With the use of such a system, travel between time in a dual command cycle is virtually eliminated resulting in a large throughput improvement. The dual shuttle system is then extended to perform an equivalent of two dual commands in one cycle in a quadruple command mode (QC). A heuristic that sequences retrievals to minimize travel time in QC mode is developed. Monte Carlo simulation results are provided for evaluating the heuristic's performance and show that it performs well, achieving large throughput improvements compared with that of the dual command cycle operating under the nearest neighbor retrieval sequencing heuristic.

Keywords:

Automated Storage/Retrieval Systems Design; Automated Storage/Retrieval Systems Operation; Material Handling Systems; Performance Modeling and Analysis

Introduction

Automated storage/retrieval systems (AS/RS) are widely used in warehousing and manufacturing applications. A typical unit load AS/RS consists of storage racks, S/R machines, link conveyors, and input/output (I/O) stations. An important system performance measure is the throughput capacity of the system. The throughput capacity for a single aisle is the inverse of the mean transaction time, which is the expected amount of time required for the S/R machine to store and/or retrieve a unit load. The service time for a transaction includes both S/R machine travel time and pickup/deposit time. This time typically depends on the configuration of the storage rack and the S/R machine specifications.

Han et al. [2] improved the throughput capacity of the AS/RS through sequencing retrievals. Intelligently sequencing the retrievals can reduce unproductive travel between time when the S/R machine is traveling empty and thereby increase the throughput. They develop an expression for the maximum possible improvement in throughput if travel between is eliminated for an AS/RS that is throughput bound and operates in dual command mode. In essence, this means that if the S/R machine travels in a single command path but performs both a storage and a retrieval operation, the above throughput improvement could be obtained.

In this paper, we analyze an alternative design of the S/R machine that has two shuttles instead of