Conveyor Parcel Routing with Order-Contiguous Arrivals

TL;DR

This paper introduces a new algorithm, DOPP, for routing parcels in conveyor systems that ensures parcels of the same order arrive consecutively, improving efficiency in warehouse logistics.

Contribution

The paper formalizes online MAPF-OC and proposes DOPP, a complete polynomial-time algorithm that guarantees order-contiguous arrivals in conveyor parcel routing.

Findings

DOPP efficiently generates high-quality plans within tight time constraints.

Experiments show DOPP's scalability on real warehouse layouts.

DOPP successfully enforces order-contiguity in parcel arrivals.

Abstract

In warehouse logistics, parcels released from the outfeed of an automated storage system must be routed through conveyor networks to workstations. Beyond collision avoidance, practical operations impose an additional requirement of order-contiguous arrivals: at each delivery point, parcels belonging to the same order must arrive as a consecutive block in the arrival sequence to reduce downstream re-sorting effort. We formalize this problem as online multi-agent path finding with order-contiguity (online MAPF-OC), where agents (i.e., parcels) appear over time and exit upon delivery. To efficiently solve online MAPF-OC, we propose Dual-Ordering Prioritized Planning (DOPP), a complete polynomial-time algorithm with a three-level structure that (i) searches order-level arrival sequences, (ii) refines agent-level priorities, and (iii) synthesizes feasible solutions via prioritized planning. Experiments on various conveyor-network layouts, including those derived from actual warehouses, demonstrate DOPP's practical scalability and ability to generate high-quality plans within tight time budgets.