Simulating Storage Policies for an Automated Grid-Based Warehouse System

Beckschäfer, Michaela; Malberg, Simon; Tierney, Kevin; Weskamp, Christoph

doi:10.1007/978-3-319-68496-3_31

Cited by 12 publications

(4 citation statements)

References 15 publications

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“…Ten Hompel et al [5,6] were, beside Wehking [7], the first who mentioned RCS/R-systems in a relevant logistical volume and gave an overview of the used technology and the advantages such as high efficiency, flexibility, and modularity. Zou et al [8], Beckschäfer et al [9], and Galka [10,11] all developed a discrete event simulation to gain information about the system. Still, no published general information about RCS/R-systems, such as the maximum throughput or number of robots on the grid.…”

Section: Literature Reviewmentioning

confidence: 99%

“…In their research, Beckschäfer et al [9] focused on warehousing strategies and whether a new product should be stored in an empty container or a container that has already been partially filled with the same product should be removed from storage to store the new stock item. Besides a fixed number of picking stations, only warehouse filling levels of around 50% and a constant stacking height of 13 containers were considered.…”

Section: Literature Reviewmentioning

confidence: 99%

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Simulation study of RCS/R-systems with several robots serving one picking station

Trost,

Karting,

Eder

2023

FME Transactions

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Robot-based compact storage and retrieval systems (RCS/RS) are fully automatic storage systems operated by robots from above. Therein, goods are stored in plastic bins stacked on each other, resulting in a 'Last-In-First-Out' storage strategy within each stack. This ensures very high degrees of space utilization. If containers located further down the stack are required, the robots relocate those stored above the required one. RCS/R-systems can typically be found in e-commerce, the pharmaceutical industry, and food or spare parts trade. Besides the system parameters, many other factors, such as the number of robots or the grid size, influence the system's behavior. This paper focuses on the system's throughput and the optimum number of operating robots. A discrete event simulation (DES) in the SIMIO simulation program gained insights into design variants and operating modes.

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Section: Literature Reviewmentioning

confidence: 99%

Section: Literature Reviewmentioning

confidence: 99%

Simulation study of RCS/R-systems with several robots serving one picking station

Trost,

Karting,

Eder

2023

FME Transactions

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“…They dig out a requested bin and transport it to a designated loading station, located at the perimeter of system. Beckschäfer et al (2017) develop a discrete event simulation model to examine bin storage policies. build a semiopen queuing network to estimate performance of an RCSRS, considering both dedicated (one product per stack, reducing bin reshuffling time) and shared (multiple products per stack) storage policies.…”

Section: Literature Reviewmentioning

confidence: 99%

Robotic Sorting Systems: Performance Estimation and Operating Policies Analysis

Zou

Koster

Gong

et al. 2021

Transportation Science

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Many distribution centers use expensive, conveyor-based sorting systems that require large buildings to house them. In areas with tight space, robotic sorting systems offer a new type of solution to sort parcels by destination. Such systems are highly flexible in throughput capacity and are now gradually being introduced, particularly in express companies. This paper studies robotic sorting system with two layouts. The first layout has two tiers: robots drive on the top tier and sort parcels by destination on spiral conveyors connected to roll containers at the lower tier. The second layout has a single tier with input and output points located at the perimeter, connected by robots. For each layout, we consider both the shortest path topology via dual-lane aisles and the detour path topology via single-lane aisles. We build closed queueing networks for performance estimation, design an iterative procedure to investigate robot congestion in the two-tier layout, and use a traffic flow function to estimate robot congestion in the single-tier layout. Random, closest, dedicated, and shortest-queue robot-to-loading-station assignment rules are examined. We validate analytical models by both simulation and a real case of Deppon Express and analyze the optimal system size and operating policies for throughput capacity and operating cost. The results show that the system throughput capacity is significantly affected by robot congestion in the single-tier layout with the detour path topology, but it is only slightly affected in the other systems. A square layout fits the shortest path and a rectangular layout fits the detour path. Both the random assignment rule and the shortest-queue assignment rule are superior for a large number of robots, whereas the dedicated assignment rule is superior for a small number of robots. We apply these insights at Deppon Express for different allocations in peak and off-peak hours. Our analysis shows that a robotic sorting system typically has lower overall annual cost than a traditional cross-belt sorting system when the required throughput capacity is not too large.

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“…• Beckschafer et al [2017], Nigam et al [2014], , Tessensohn et al [2020], , Xiang et al [2018], Yuan et al [2018], Zou et al [2018] for papers dealing with storage issues; and…”

Section: Literature Review: Structurementioning

confidence: 99%

Order allocation, rack allocation and rack sequencing for pickers in a mobile rack environment

Valle¹,

Beasley²

2019

Preprint

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In this paper we investigate the problem of simultaneously allocating orders and mobile storage racks to static pickers. Here storage racks are allocated to pickers to enable them to pick all of the products for the orders that have been allocated to them. Problems of the type considered here arise in facilities operating as robotic mobile fulfilment systems.We present a formulation of the problem of allocating orders and racks to pickers as an integer program and discuss the complexity of the problem. We present two heuristics (matheuristics) for the problem, one using partial integer optimisation, that are directly based upon our formulation.We also consider the problem of how to sequence the racks for presentation at each individual picker and formulate this problem as an integer program. We prove that, subject to certain conditions being satisfied, a feasible rack sequence for all orders can be produced by focusing on just a subset of the orders to be dealt with by the picker.Computational results are presented, both for order and rack allocation, and for rack sequencing, for randomly generated test problems (that are made publicly available) involving up to 500 products, 150 orders, 150 racks and 10 pickers.

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Simulating Storage Policies for an Automated Grid-Based Warehouse System

Cited by 12 publications

References 15 publications

Simulation study of RCS/R-systems with several robots serving one picking station

Simulation study of RCS/R-systems with several robots serving one picking station

Robotic Sorting Systems: Performance Estimation and Operating Policies Analysis

Order allocation, rack allocation and rack sequencing for pickers in a mobile rack environment

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