Automated battery replacement mechanism for drones

Abstract

Currently, there have been numerous solutions to solve the problem of increasing the flight time for drones. For example, quadrotors which are used in applications such as search and rescue, surveillance and many more. In the aspect of extending flight time, there are solutions provided commercially where automated battery exchange stations or battery charging stations are developed for drones to land on and have its battery recharged or swapped. The problem with these ground-based battery charging or swapping solutions is that the drone needs to deviate from its intended flight path and make a detour towards the ground station. This inefficiency results in the loss of drone operation time, increased spatial cost with the installation of ground stations. In addition, it will have restricted aerial deployment of drones to areas around the station as the drones needs to have ample time to return to the station to change or recharge its battery. Hence, this paper introduces a method of increasing drone operating time by means of in-flight battery swapping. This method is inspired by the refuelling technique used by fighter jets to achieve a longer flight time without having to carry a larger fuel tank. This will allow the drone to maintain its flight trajectory while the old battery is being replaced with a fully charged battery. A rotating mechanism is designed in Solidworks to ensure the design is feasible before creating it. Firstly, the main drone will dock with the service drone, the main drone will then draw power from the service drone before the battery swap commences. The way the mechanism works is that a H-bridge will hold on to 2 sets of batteries, one fully charged and the drained one from the main drone. This H-bridge will then be rotated to change the old battery with the new one. Magnetic connectors will be used to connect the battery case to the main drone. While the new battery will be held in place by the main drone through the use of 4 solenoids. A proof of concept is fabricated using 3D printing and Acrylic. The material used in the 3D printing is Polylatic Acid (PLA). This swapping mechanism is shown to perform as well as land-based swapping in terms of the time it takes to switch out the battery of the main drone.