自動儲存與檢索系統（AS/RS）與穿梭車式儲存與檢索系統（SBS/RS）是主流物料搬運系統（MHS）技術，旨在提高倉庫效率和自動化程度。當客戶需求和庫存水平劇烈變動時，現有倉儲系統可能不再適合或滿足新的挑戰，使得系統面臨變更和升級，這通常是非常複雜且昂貴；因此，初始系統的配置至關重要。
本研究提出了一種公正的比較策略，用於衡量系統性能與適用情境。我們利用FlexSim這項3D模擬與分析工具對現實中的AS/RS進行複製模擬，並轉換為兩種主流的SBS/RS類型，即tier-captive SBS/RS和tier-to-tier SBS/RS。隨後，共進行了108種不同配置下的模擬實驗，包含三種系統、三種貨架設計、三種S/R機器移動速度和四種存儲策略，同時極力減少瓶頸資源的影響，例如通過改變貨架設計降低旅行時間和調整S/R機器速度。
研究結果顯示， tier-captive SBS/RS在採用ABC存儲策略可實現最高吞吐量，約為所研究的AS/RS案場的3.22倍。除此之外，本研究發現一種新的指標衡量方式，透過考慮吞吐量、利用率和等待時間等性能指標，打破吞吐量與等待時間的反比關係，能夠正確區分系統間的性能優劣。

Automated Storage and Retrieval Systems (AS/RS) and Shuttle-based Storage and Retrieval Systems (SBS/RS) are mainstream Material Handling System (MHS) technologies designed to improve warehouse efficiency and automation. When customer demand and inventory levels change dramatically, existing warehouse systems may no longer be able to handle or respond to the new challenges. The system must be changed and upgraded, which is often very complex and expensive. Therefore, the initial system configuration is critical.
This study proposes an unbiased comparison strategy for measuring system performance and applicability and using the 3D simulation and analysis tool FlexSim to simulate a real AS/RS replica. Moreover, convert it into two mainstream SBS/RS types, i.e., tier-captive SBS/RS and tier-to-tier SBS/RS. Subsequently, 108 configurations were simulated, including three systems, three rack designs, three S/R machine travel speeds, and four storage policies. The impact of bottleneck sources was minimized by changing the rack design, reducing travel time, and adjusting S/R machine speeds.
The study results show that tier-captive SBS/RS with ABC storage policy achieves the highest throughput, 222% higher than the AS/RS case study. In addition, a new metric measurement method is found in this study, which breaks the inverse relationship between throughput and wait time by considering the performance metrics such as throughput, utilization, and waiting time and can correctly evaluate the performance advantages and disadvantages among systems.

[1] Roodbergen, Kees Jan, and Iris FA Vis. "A survey of literature on automated storage and retrieval systems." European journal of operational research 194.2 (2009): 343-362.
[2] Küçükyaşar, Melis, Banu Y. Ekren, and Tone Lerher. "Cost and performance comparison for tier‐captive and tier‐to‐tier SBS/RS warehouse configurations." International transactions in operational research 28.4 (2021): 1847-1863.
[3] Gu, Jinxiang, Marc Goetschalckx, and Leon F. McGinnis. "Research on warehouse operation: A comprehensive review." European journal of operational research 177.1 (2007): 1-21.
[4] Reyes, J., E. Solano-Charris, and J. Montoya-Torres. "The storage location assignment problem: A literature review." International Journal of Industrial Engineering Computations 10.2 (2019): 199-224.
[5] Tanaka, Shunji, and Mituhiko Araki. "Routing problem under the shared storage policy for unit-load automated storage and retrieval systems with separate input and output points." International Journal of Production Research 47.9 (2009): 2391-2408.
[6] Larco, José Antonio. "Managing warehouse efficiency and worker discomfort through enhanced storage assignment decisions." International Journal of Production Research 55.21 (2017): 6407-6422.
[7] Yan, Xiaohui. "An NSABC algorithm for multi-aisle AS/RS scheduling optimization." Computers & Industrial Engineering 156 (2021): 107254.
[8] Marolt, Jakob, Nenad Kosanić, and Tone Lerher. "Relocation and storage assignment strategy evaluation in a multiple-deep tier captive automated vehicle storage and retrieval system with undetermined retrieval sequence." The International Journal of Advanced Manufacturing Technology (2022): 1-18.
[9] Lewczuk, Konrad. "The study on the automated storage and retrieval system dependability." Eksploatacja i Niezawodność 23.4 (2021): 709-718.
[10] Ekren, Banu Y., and Sunderesh S. Heragu. "Performance comparison of two material handling systems: AVS/RS and CBAS/RS." International Journal of Production Research 50.15 (2012): 4061-4074.
[11] Gagliardi, Jean-Philippe, Jacques Renaud, and Angel Ruiz. "A simulation modeling framework for multiple-aisle automated storage and retrieval systems." Journal of Intelligent Manufacturing 25 (2014): 193-207.
[12] Yetkin Ekren, Banu. "A multi-objective optimization study for the design of an AVS/RS warehouse." International Journal of Production Research 59.4 (2021): 1107-1126.
[13] Lerher, Tone. "Travel time models for double-deep automated storage and retrieval systems." International Journal of Production Research 48.11 (2010): 3151-3172.
[14] Lerher, Tone. "Travel time model for double-deep shuttle-based storage and retrieval systems." International Journal of Production Research 54.9 (2016): 2519-2540.
[15] Li, Jiaxi, Mohsen Moghaddam, and Shimon Y. Nof. "Dynamic storage assignment with product affinity and ABC classification—a case study." The International Journal of Advanced Manufacturing Technology 84 (2016): 2179-2194.
[16] Ramtin, Faraz, and Jennifer A. Pazour. "Product allocation problem for an AS/RS with multiple in-the-aisle pick positions." IIE Transactions 47.12 (2015): 1379-1396.
[17] Zhen, Lu, and Haolin Li. "A literature review of smart warehouse operations management." Frontiers of Engineering Management 9.1 (2022): 31-55.
[18] Yener, Furkan. "Class based storage with mixed integer linear programming approach for hazardous materials storage." POLISH ACAD SCIENCES INST PHYSICS, 2019.
[19] Ekren, Banu Y. "A simulation-based experimental design for SBS/RS warehouse design by considering energy related performance metrics." Simulation Modelling Practice and Theory 98 (2020): 101991.
[20] Marchet, Gino. "Development of a framework for the design of autonomous vehicle storage and retrieval systems." International Journal of Production Research 51.14 (2013): 4365-4387.
[21] Jerman, Boris. "Simulation-based performance analysis for a novel avs/rs technology with movable lifts." Applied Sciences 11.5 (2021): 2283.
[22] Lehmann, Timo, and Jakob Hußmann. "Travel time model for multi-deep automated storage and retrieval systems with different storage strategies." International Journal of Production Research (2022): 1-16.
[23] Li, Yi, and Zhiyang Li. "Shuttle-Based Storage and Retrieval System: A Literature Review." Sustainability 14.21 (2022): 14347.