A Demand-Aware Replenishment Policy Design for Robotic Mobile Fulfillment Systems: A Throughput-Energy Trade-Off Analysis

Timony, Catherine Laura Lee (2026) A Demand-Aware Replenishment Policy Design for Robotic Mobile Fulfillment Systems: A Throughput-Energy Trade-Off Analysis. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Robotic Mobile Fulfilment Systems (RMFS) improve warehouse efficiency by using robots to transport pods between storage area and workstations. However, the performance of an RMFS depends not only on order picking, but also on how inventory replenishment is handled. Replenishment competes with picking for the same robot fleet and it becomes more complex under scattered storage. This study proposes a demand-aware replenishment policy that integrates reorder points for each stock keeping unit (SKU) with an opportunity score for Replenishment Pod Selection (RPS) that evaluates and prioritises candidate pods according to their potential to recover critical SKU shortages. The policy was evaluated using an agent-based simulation developed in NetLogo and integrated with Python as the decision-making layer. It was benchmarked against the Warehouse Inventory–SKU in Pod policy as the baseline. The simulation tested different lead time settings and replenishment station capacities to examine how trigger timing and station capacity affect system performance. Performance was assessed using order throughput, total energy consumption, energy per fulfilled order, replenishment-to-pick ratio, and pile-on. With a 15-minute internal replenishment lead time, the proposed policy increased throughput by 6.1 to 13.9 percent, reduced the replenishment-to-pick ratio by 12 to 15 percent, and lowered energy per fulfilled order by 1.5 to 2.6 percent relative to the baseline. Increasing station capacity beyond two pods exhibited a saturation effect, as it produced no significant additional throughput gain but increased replenishment workload and energy use. Pareto front analysis further identified the configuration with a 15-minute internal replenishment lead time and a one-pod station capacity as a balanced operating point. In contrast, a two-pod capacity is preferable when throughput is prioritized.
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Robotic Mobile Fulfilment Systems (RMFS) meningkatkan efisiensi gudang melalui penggunaan robot untuk memindahkan pod antara area penyimpanan dan stasiun kerja. Namun, kinerja RMFS tidak hanya ditentukan oleh proses pengambilan pesanan (picking), tetapi juga oleh proses pengisian ulang (replenishment). Replenishment bersaing dengan picking dalam memanfaatkan armada robot dan menjadi semakin kompleks pada sistem penyimpanan tersebar. Penelitian ini mengusulkan kebijakan replenishment yang mengintegrasikan titik pemesanan ulang (reorder point) untuk setiap stock keeping unit (SKU) dengan opportunity score untuk Replenishment Pod Selection (RPS) yang menilai dan memprioritaskan pod berdasarkan potensinya dalam memulihkan kekurangan SKU kritis. Kebijakan ini dievaluasi menggunakan simulasi berbasis agen yang dikembangkan dalam NetLogo dan Python sebagai lapisan pengambilan keputusan. Kebijakan usulan ini dibandingkan dengan Warehouse Inventory–SKU in Pod sebagai kebijakan dasar. Simulasi menguji beberapa pengaturan lead time serta kapasitas stasiun replenishment untuk menilai bagaimana waktu pemicuan dan kapasitas stasiun memengaruhi kinerja sistem. Kinerja diukur berdasarkan throughput pesanan, konsumsi energi, rasio replenishment terhadap picking, dan pile-on. Dengan lead time 15 menit, kebijakan ini meningkatkan throughput sebesar 6,1 hingga 13,9 persen, menurunkan beban kerja replenishment sebesar 12 hingga 15 persen, serta mengurangi konsumsi energi per pesanan terpenuhi sebesar 1,5 hingga 2,6 persen dibandingkan kebijakan dasar. Kapasitas stasiun di atas dua pod menunjukkan efek saturasi yang tidak meningkatkan throughput, namun meningkatkan beban kerja replenishment dan konsumsi energi. Analisis Pareto front mengidentifikasi konfigurasi lead time 15 menit dan kapasitas stasiun satu pod sebagai titik operasi yang seimbang, sedangkan kapasitas dua pod disarankan ketika throughput diprioritaskan.

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	Robotic Mobile Fulfillment System, Replenishment Policy, Replenishment Pod Selection, Energy Consumption, Pareto Front Analysis, Kebijakan Replenishment, Konsumsi Energi, Analisis Pareto Front
Subjects:	T Technology > TJ Mechanical engineering and machinery > TJ211.415 Mobile robots
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Industrial Engineering > 26101-(S2) Master Thesis
Depositing User:	Catherine Laura Lee Timony
Date Deposited:	03 Aug 2026 01:46
Last Modified:	03 Aug 2026 01:46
URI:	http://repository.its.ac.id/id/eprint/141791

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