Flying batteries: In-flight battery switching to increase multirotor flight time
This addresses flight endurance for multirotor drones without significantly increasing mass or safety risks, representing an incremental but practical advancement.
The paper tackles the problem of limited flight time for multirotors by introducing in-flight battery switching via mid-air docking, resulting in a 4.7x increase in flight time compared to solo flight and a 2.2x improvement over theoretical limits.
We present a novel approach to increase the flight time of a multirotor via mid-air docking and in-flight battery switching. A main quadcopter flying using a primary battery has a docking platform attached to it. A 'flying battery' - a small quadcopter carrying a secondary battery - is equipped with docking legs that can mate with the main quadcopter's platform. Connectors between the legs and the platform establish electrical contact on docking, and enable power transfer from the secondary battery to the main quadcopter. A custom-designed circuit allows arbitrary switching between the primary battery and secondary battery. We demonstrate the concept in a flight experiment involving repeated docking, battery switching, and undocking. The experiment increases the flight time of the main quadcopter by a factor of 4.7x compared to solo flight, and 2.2x a theoretical limit for that given multirotor. Importantly, this increase in flight time is not associated with a large increase in overall vehicle mass or size, leaving the main quadcopter in fundamentally the same safety class.