Vehicle Routing Problems for Drone Delivery

TL;DR

This paper develops new vehicle routing problems tailored for drone delivery, incorporating energy consumption models and multi-trip capabilities, to optimize costs and delivery times in practical scenarios.

Contribution

It introduces two novel multi-trip VRPs for drone delivery that account for energy use, drone reuse, and battery constraints, validated through experiments and heuristics.

Findings

Energy consumption varies linearly with payload and battery weight.

Reusing drones significantly reduces costs.

Optimal battery size impacts delivery efficiency.

Abstract

Unmanned aerial vehicles, or drones, have the potential to significantly reduce the cost and time of making last-mile deliveries and responding to emergencies. Despite this potential, little work has gone into developing vehicle routing problems (VRPs) specifically for drone delivery scenarios. Existing VRPs are insufficient for planning drone deliveries: either multiple trips to the depot are not permitted, leading to solutions with excess drones, or the effect of battery and payload weight on energy consumption is not considered, leading to costly or infeasible routes. We propose two multi-trip VRPs for drone delivery that address both issues. One minimizes costs subject to a delivery time limit, while the other minimizes the overall delivery time subject to a budget constraint. We mathematically derive and experimentally validate an energy consumption model for multirotor drones, demonstrating that energy consumption varies approximately linearly with payload and battery weight. We use this approximation to derive mixed integer linear programs for our VRPs. We propose a cost function that considers our energy consumption model and drone reuse, and apply it in a simulated annealing (SA) heuristic for finding sub-optimal solutions to practical scenarios. To assist drone delivery practitioners with balancing cost and delivery time, the SA heuristic is used to show that the minimum cost has an inverse exponential relationship with the delivery time limit, and the minimum overall delivery time has an inverse exponential relationship with the budget. Numerical results confirm the importance of reusing drones and optimizing battery size in drone delivery VRPs.