We study robotic mobile fulfilment systems for online retailers, where products are stored in movable shelves and robots transport shelves. While previous studies assume random assignment rule of workstations to robots, we propose an based on handling speeds design a neighbourhood search algorithm find near optimal rule. build semi-open queueing networks use two-phase approximate approach performance estimation. first replace workstation service processes by composite node then solve the...

Many distribution centers use expensive, conveyor-based sorting systems that require large buildings to house them. In areas with tight space, robotic offer a new type of solution sort parcels by destination. Such are highly flexible in throughput capacity and now gradually being introduced, particularly express companies. This paper studies system two layouts. The first layout has tiers: robots drive on the top tier destination spiral conveyors connected roll containers at lower tier....

Robotic compact storage and retrieval systems (RCSRS) have seen many implementations over the last few years. In such a system, inventory items are stored in bins, organized grid. each cell of grid, certain number bins on top other. Robots with transport lifting capabilities move grid roof to between manual workstations stacks. We estimate performance evaluate policies RCSRS, considering both dedicated shared coupled random zoned Semi-open queuing networks (SOQNs) built system performance,...

Drones are increasingly used to deliver packages with high efficiency in several areas. We study a multi-warehouse drone delivery system, considering the allocation rule that all warehouses share drones and each warehouse owns its drones. Both plug-in charge battery swap strategies investigated for management. examine random closest assignment rules, design heuristic improve rule. A closed queueing network is built estimate maximum throughput capacity cost minimisation model developed...

AbstractDrones are increasingly used for last-mile delivery due to their speed and cost-effectiveness. This study focuses on a novel locker-drone system, where trucks transport parcels from the warehouse lockers, drones complete final delivery. system is ideal community intra-facility logistics. The research optimises network design by determining location of number at each locker, assignment demands minimising operating costs. Both single-parcel multi-parcel capacity examined. We build an...

Three-dimensional compact automated storage/retrieval systems (AS/RS) have been extensively applied in warehouses, with advantages of full automation, time efficiency and high space utilisation. While previous studies that use lower mid-point input/output (I/O) dwell point policy consider single-command cycles (SC), this paper builds travel-time models dual-command (DC). The S/R crane also dwells the rack when it is idle. We validate analytical using simulation to optimise system dimensions....

This paper studies a three-dimensional automated storage and retrieval system that uses conveyors for depth transportation crane both horizontal vertical transportation. While previous put input output points together at the bottom, we consider separating elevating them by proposing four I/O point policies: two sides, elevated one side, midpoint. We build travel time models to analyse these policies use simulation validation. theoretically find optimal structure compare policies, in terms of...

Abstract Autonomous mobile robots are increasingly used for order picking, delivery, and parcel sorting. This article studies a robotic sorting system that uses to transport parcels from loading stations drop‐off points. While this provides more flexible throughput capacity than conventional systems, its performance is significantly affected by the robot travel distance congestion. We study problem of assigning destinations points minimize time, trading off First, an open queuing network...

Double-deep multi-aisle automated storage/retrieval systems are increasingly applied for storing and retrieving unit loads, with advantages of increased space utilisation, reduced number aisles improved efficiency storage rack (S/R) machines. In such systems, the retrieval process may consist rearrangement blocking based on assumptions uniformly distributed locations random policy. We formulate analytical travel-time models both single- dual-command cycles under three rules. validate by...

Last-mile delivery is a costly and time-consuming process in e-commerce operations. Piloted by several companies, autonomous mobile robots cooperating with trucks have been implemented for parcel delivery. In this system, truck departs from the warehouse, carrying parcels, traverses drop-off points to release or deliver parcels itself. We focus on performance estimation system configuration, considering no-zoning policy, where all serve whole area zoning each takes charge of one zone. A...

Abstract In the bicycle-sharing operation network, mismatch between supply and demand as well indiscriminate bicycle parking have caused waste of resources increased management costs for operators. This study presents design a bike-sharing electronic fences location developed Hunan University Technology Business. this paper, we constructed Site Selection Model with Constrained Service Level use Hybrid Genetic & Annealing algorithm (HGAA) to adjust balance sharing bicycles objective...

A traditional flow-rack automated storage and retrieval system stores unit-loads in lanes with the same slope. This paper considers a new bi-directional system, which adjacent slope to opposite directions. While such can conduct dual-command cycle, it is critical operate an efficient way. We focus on both pickup/deposit (P/D) station policy dwell point location policy, considering two scenarios for each policy. first build single-command travel time models examined P/D Then, we validate...