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
生煎Adhinarayan Kerla
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@tamu.edu
Abstract
This paper address the throughput improvement possible with the u of a dual shuttle automated storage and retrieval system. With the u 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 quences 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 quencing heuristic.
Keywords:
Automated Storage/Retrieval Systems Design; Automated Storage/Retrieval Systems Operation; Material Handling Systems; Performance Modeling and Analysis
Introduction
隐形除皱
Automated storage/retrieval systems (AS/RS) are widely ud 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 inver 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 rvice 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 quencing retrievals. Intelligently quencing the retrievals can reduce unproductive travel between time when the S/R machine is traveling empty and thereby increa 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 esnce, this means that if the S/R machine travels in a single comm
and path but performs both a storage and a retrieval operation, the above throughput improvement could be obtained.
cm和弦In this paper, we analyze an alternative design of the S/R machine that has two shuttles instead of one as in a regular AS/RS. The new design eliminates the travel between the storage and retrieval points and performs both a storage and a retrieval at the point of retrieval, thereby achieving the maximum throughput increa calculated by Han et al. [3].
小学生二年级日记
The dual shuttle AS/RS is a new design aimed at improving S/R machine performance. most studies on AS/RS systems have been bad on a single shuttle design. In our analysis of the dual shuttle AS/RS performance, we build upon the previous rearch results.
折损的意思Alternative S/R Machine Design
A typical unit-load AS/RS has an S/R machine operating in each aisle of the system. The
清炖鲤鱼的家常做法S/R machine has a mast which is supported at the floor and the ceiling and travels horizontally within the aisle. Connected to this mast is a shuttle mechanism that carries the unit load and moves vertically up and down the mast. The shuttle mechanism also transfers loads in and out of storage locations in the rack. Figure 1 provides an illustration of the single shuttle S/R machine.
怎么做自我介绍
Figure 1. Single Shuttle S/R Machine Design
A typical single shuttle AS/RS can perform a single command cycle or a dual command cycle. A single command cycle consists of either a storage or a retrieval. For a storage, the time consists of the time to pickup the load at the I/O point, travel to the storage point, deposit the load at that point, and return to the I/O point. The time for a retrieval is developed similarly.
公主房A dual command cycle involves both a storage and a retrieval in the same cycle. The cycle time involves the time to pickup the load at the I/O point, travel to the storage location, place the load in the rack, travel empty to the retrieval location, retrieve a load, r
eturn to the I/O point, and deposit the load at the I/O point.
If we critically analyze the dual command cycle of the S/R machine (shown by the solid line in Figure 2), a potential open location for a future storage is created when a retrieval is performed. Furthermore, if both a retrieval and a storage are performed at the same point, the travel between time (TB) is eliminated, and the travel time will be equal to the single command travel time. With the existing AS/RS design, this mode of operation is not possible; therefore, an alternative to the S/R machine, a dual shuttle R/S machine, is propod.
