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Trolley line picking: storage assignment and order sequencing to increase picking performance

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David Füßler at Friedrich Schiller University Jena
David Füßler
Nils Boysen at Friedrich Schiller University Jena
Nils Boysen
Konrad Stephan
Konrad Stephan
Konrad Stephan
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Abstract and Figures

Trolley line picking is a special warehousing system particularly suited to fulfill high-volume demands for heavy stock keeping units (SKUs). In such a system, unit loads of SKUs are positioned along a given path passed by automated trolleys, i.e., carriers hanging from a monorail or automated guided vehicles. Once a trolley reaches a requested SKU, it automatically stops and announces the requested items on a display. This is the signal for an accompanying human picker to put the demanded items onto the trolley. In this way, picking continues until, at the end of the path, the current picking order is complete and the trolley moves onward to the shipping area. Meanwhile, the picker rushes back to meet the subsequent trolley associated with the next picking order. The picking performance of the trolley line system is mainly influenced by the picker’s unproductive walking from SKU to SKU during order processing and back to the next trolley when switching to the next order. In this paper, we investigate how the storage assignment of SKUs along the path and the order sequence influence picking performance. Specifically, we explore the positive effect of duplicating SKUs and storing them at multiple positions along the path. We formulate the interdependent storage assignment and order sequencing problems and introduce a decomposition heuristic. Our computational study investigates the solution performance of this procedure and shows that SKU duplication can considerably improve picking performance.
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OR Spectrum (2019) 41:1087–1121
https://doi.org/10.1007/s00291-019-00566-9
REGULAR ARTICLE
Trolley line picking: storage assignment and order
sequencing to increase picking performance
David Füßler1·Nils Boysen1·Konrad Stephan1
Received: 15 March 2019 / Accepted: 17 October 2019 / Published online: 2 November 2019
© Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract
Trolley line picking is a special warehousing system particularly suited to fulfill high-
volume demands for heavy stock keeping units (SKUs). In such a system, unit loads
of SKUs are positioned along a given path passed by automated trolleys, i.e., carri-
ers hanging from a monorail or automated guided vehicles. Once a trolley reaches a
requested SKU, it automatically stops and announces the requested items on a display.
This is the signal for an accompanying human picker to put the demanded items onto
the trolley. In this way, picking continues until, at the end of the path, the current pick-
ing order is complete and the trolley moves onward to the shipping area. Meanwhile,
the picker rushes back to meet the subsequent trolley associated with the next picking
order. The picking performance of the trolley line system is mainly influenced by the
picker’s unproductive walking from SKU to SKU during order processing and back to
the next trolley when switching to the next order. In this paper, we investigate how the
storage assignment of SKUs along the path and the order sequence influence picking
performance. Specifically, we explore the positive effect of duplicating SKUs and stor-
ing them at multiple positions along the path. We formulate the interdependent storage
assignment and order sequencing problems and introduce a decomposition heuristic.
Our computational study investigates the solution performance of this procedure and
shows that SKU duplication can considerably improve picking performance.
Keywords Warehousing ·Trolley line picking ·Order fulfillment ·Scheduling
BNils Boysen
nils.boysen@uni-jena.de
http://www.om.uni-jena.de/
David Füßler
david.fuessler@uni-jena.de
Konrad Stephan
konrad.stephan@uni-jena.de
1Lehrstuhl für Operations Management, Friedrich-Schiller-Universität Jena, Carl-Zeiß-Straße 3,
07743 Jena, Germany
123
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
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