Browsing by Author "Lerher, Tone"

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Autonomous mobile robot travel under deadlock and collision prevention algorithms by agent-based modelling in warehouses
    (Taylor and Francis, 2022-10-31) Eroglu Turhanlar, Ecem; Yetkin Ekren, Banu; Lerher, Tone
    Recent dramatic increase in e-commerce has also increased the adoption of automation technologies in warehouses. Autonomous mobile robots (AMRs) are from those technologies widely utilized in warehouse operations. It is important to design the operation of those robotic systems in such a way that, they meet the current and future system requirements correctly. In this paper, we study flexible travel of AMRs in warehouses by developing smart deadlock and collision prevention algorithms on agent-based modelling. By that, AMR agents can interact with each other and environment, so that they can make smart decisions maximizing their goals. We compare the performance of the developed flexible travel system with non-flexible designs where there is a single AMR dedicated to a specific zone so that no deadlock or collision possibility takes place. The results show that AMRs may provide up to 39% improvement in the flexible system compared to its non-flexible design.
  • Thumbnail Image
    ItemOpen Access
    Cost and performance comparison of tier-captive SBS/RS with a novel AVS/RS/ML
    (Taylor and Francis, 2023-04-18) Ekren, Banu Y.; Lerher, Tone; Küçükyaşar, Melis; Jerman, Boris
    This paper introduces a novel autonomous vehicle-based storage and retrieval system that utilizes movable lifts (AVS/RS/ML), proposed as an alternative to the tier-captive shuttle-based storage and retrieval system (SBS/RS). The newly proposed system aims to provide an affordable solution with highly utilised AGVs, that can also perform operations out of warehouse. The performance of this novel system is compared with the equivalent tier-captive SBS/RS warehouse design, where each shuttle is dedicated in a specific tier in that design. The comparison is based on the initial system investments costs, throughput rates, and average utilisation of lifts/MLs in the system. Collision prevention rules are also applied to AVS/RS/ML, and its performance is tested through simulation. The results show that the tier-captive SBS/SR system becomes cost-efficient under high throughput rate requirements, while the AVS/RS/ML technology is preferred for relatively moderate and low process rate requirements. The unit-cost per month performance metric of AVS/RS/ML is less sensitive to an increase in number of tiers in the system, compared to the tier-captive SBS/RS case, indicating that AVS/RS/ML may be promising for high-tier warehouse system designs.
  • Thumbnail Image
    ItemEmbargo
    Design and operation of single- and multi-deep shuttle-based storage and retrieval systems (SBS/RS)
    (Springer, 2024) Lerher, Tone; Marolt, Jakob; Sgarbossa, Fabio; Ekren, Banu Y.; Dukic, Goran; Manzini, Riccardo; Accorsi, Riccardo
    With the rapid growth of e-commerce practices, the efficient management of warehouses and fulfilment centres has become crucial in supply chain operations. One effective strategy for achieving this efficiency is the digital transformation of warehouses through automation. In particular, shuttle-based storage and retrieval systems (SBS/RS) have gained significant attention due to their ultra-high transaction process capability. However, ongoing research focuses on enhancing the operating performance and cost efficiency of these SBS/RS designs. This chapter presents mathematical modelling approaches for estimating the performance of single- and multi-deep SBS/RS designs. These models provide valuable insights for designing warehouses that optimize transaction process rates while ensuring a balanced utilization of elevators and shuttles in the system, tailored to meet the specific requirements of the warehouse. By leveraging these modelling techniques, warehouse managers can make informed decisions regarding the design and configuration of SBS/RSs to improve overall operational efficiency and productivity.