IEEE Spectrum's weekly Video Friday roundup features a modular aerial robot concept in which two birotors, each a two-rotor flying unit, join to form a single quadrotor. The title points to a reconfigurable design: smaller flying modules that operate on their own can also be combined into a larger four-rotor vehicle.
Modular and reconfigurable drones are an active research area. Splitting a vehicle into units that can fly alone or together could let one system adapt to different tasks, for example flying separately to cover more ground and then docking for a job that needs the stability or capability of a full quadrotor. The source summary gives no technical specifications, performance figures, or details of the docking mechanism, so those are not covered here.
Video Friday is IEEE Spectrum's regular collection of recent robotics videos from labs and companies. Readers can watch the birotor-to-quadrotor demonstration and the rest of the roundup on the IEEE Spectrum page.