# Algorithms for Routing of Unmanned Aerial Vehicles with Mobile Recharging Stations

## TL;DR

This paper introduces a novel algorithm for planning UAV tours with mobile and stationary recharging stations, optimizing routes and recharge points in a complex variant of the TSP, with practical solutions demonstrated through simulations.

## Contribution

It formulates a new TSP variant involving mobile recharging stations and provides an algorithm that optimally plans UAV routes, recharge points, and UGV support, addressing NP-hardness.

## Key findings

- Algorithm effectively plans UAV routes with mobile recharging stations.
- Simulation results show practical running times for realistic instances.
- Supports minimizing UGVs needed for uninterrupted UAV missions.

## Abstract

We study the problem of planning a tour for an energy-limited Unmanned Aerial Vehicle (UAV) to visit a set of sites in the least amount of time. We envision scenarios where the UAV can be recharged along the way either by landing on stationary recharging stations or on Unmanned Ground Vehicles (UGVs) acting as mobile recharging stations. This leads to a new variant of the Traveling Salesperson Problem (TSP) with mobile recharging stations. We present an algorithm that finds not only the order in which to visit the sites but also when and where to land on the charging stations to recharge. Our algorithm plans tours for the UGVs as well as determines best locations to place stationary charging stations. While the problems we study are NP-Hard, we present a practical solution using Generalized TSP that finds the optimal solution. If the UGVs are slower, the algorithm also finds the minimum number of UGVs required to support the UAV mission such that the UAV is not required to wait for the UGV. Our simulation results show that the running time is acceptable for reasonably sized instances in practice.