EverFly: An Autonomous Drone Battery Exchange System

Abstract

This Princeton University senior thesis documents the design and fabrication of an autonomous battery exchange system for a quadcopter. Due to the nature of aircraft flight and battery weight, all drones are constrained by limited flight time. The prototypical EverFly system, outlined in this report, provides a solution to this limitation on drone battery life by enabling a DJI Tello drone to autonomously exchange its battery with a grounded station. The 80-gram Tello was programmed to autonomously guide, navigate, and control itself to the battery station upon detection of low battery. Once the Tello achieves the desired pose and lands, the battery station autonomously secures the drone, extracts its depleted battery, and replaces it with one that is fully charged. Equipped with a fully charged battery, the drone takes off and resumes its autonomous mission. The EverFly system, with a sufficient number of batteries and continuous power input, can facilitate the perpetual quasi-continuous flight of the Tello drone. This report details the modification of the Tello, the design and fabrication of EverFly's hardware subsystems, and the development of EverFly's software architecture. Although full completion of the project was interrupted by the onset of the COVID-19 pandemic, EverFly accomplished the critical goal of executing a successful autonomous battery exchange.