Design, Modeling, and Analysis of Vertical Robotic Storage and Retrieval Systems

51 Pages Posted: 22 Dec 2016 Last revised: 6 May 2018

See all articles by Kaveh Azadeh

Kaveh Azadeh

Erasmus University Rotterdam (EUR) - Rotterdam School of Management (RSM)

Debjit Roy

Indian Institute of Management (IIM), Ahmedabad

M. B. M. de Koster

Erasmus University Rotterdam (EUR) - Department of Technology and Operations Management

Date Written: December 21, 2016

Abstract

Autonomous vehicle-based storage and retrieval systems are commonly used in e-commerce fulfillment as they allow a high and flexible throughput capacity. In these systems, roaming robots transport loads between a storage location and a workstation. Two main variants exist: Horizontal, where the robots only move horizontally and use lifts for vertical transport and a new variant Vertical, where the robots can also travel vertically in the rack. This paper builds a framework to analyze the performance of the vertical system and to compare its throughput capacity with the horizontal system. We build closed-queueing network models for this that in turn are used to optimize the design. The results show that the optimal height-to-width ratio of a vertical system is around 1. As a large number of system robots may lead to blocking and delays, we compare the effect of two different robot blocking protocols on the system throughput: robot Recirculation and Wait-On-Spot. The Wait-On-Spot policy produces a higher system throughput when the number of robots in the system is small. However, for a large number of robots in the system, the Recirculation policy dominates the Wait-On-Spot policy. Finally, we compare the operational costs of the vertical and the horizontal transport system. For systems with one load/unload (L/U) point, the vertical system always produces a similar or higher system throughput, with a lower operating cost compared to the horizontal system with a discrete lift. It also outperforms the horizontal system with a continuous lift in systems with two L/U points.

Keywords: Internal transportation, robotic technology, queueing networks, performance analysis, blocking

Suggested Citation

Azadeh, Kaveh and Roy, Debjit and de Koster, M.B.M. René, Design, Modeling, and Analysis of Vertical Robotic Storage and Retrieval Systems (December 21, 2016). ERIM Report Series. Available at SSRN: https://ssrn.com/abstract=2888615 or http://dx.doi.org/10.2139/ssrn.2888615

Kaveh Azadeh (Contact Author)

Erasmus University Rotterdam (EUR) - Rotterdam School of Management (RSM) ( email )

P.O. Box 1738
Room T08-21
3000 DR Rotterdam, 3000 DR
Netherlands

Debjit Roy

Indian Institute of Management (IIM), Ahmedabad ( email )

Vastrapur
Ahmedabad, Gujarat 380 015
India

M.B.M. René De Koster

Erasmus University Rotterdam (EUR) - Department of Technology and Operations Management ( email )

RSM Erasmus University
PO Box 1738
3000 DR Rotterdam
Netherlands
+31 10 408 1719 (Phone)
+31 10 408 9014 (Fax)

HOME PAGE: http://www.rsm.nl/rdekoster

Register to save articles to
your library

Register

Paper statistics

Downloads
99
Abstract Views
465
rank
265,285
PlumX Metrics