Abstract

This paper presents the Delivery Drone Routing Problem with Limited Inventory (DDRPI), an extension of the Pickup-to-Delivery Drone Routing Problem (PDDRP). In the PDDRP, each customer may order multiple products, and each facility is assumed to hold unlimited inventory of all products. In the DDRPI, this assumption is removed: not all products are necessarily available at a single facility, which may require drones to visit multiple facilities to fulfill a customer's order. A mixed integer linear programming model is formulated to solve the problem. However, due to the high computational complexity of the DDRPI, CPLEX can only solve small instances. Therefore, a hybrid metaheuristic combining GRASP with a VND procedure is employed to address larger instances. Computational experiments are conducted to assess the limitations of the exact approach, the effectiveness of the proposed metaheuristic, the impact of drone battery constraints on the objective function, and the influence of different demand and inventory distribution patterns.