SplitFlyer Air: A Modular Quadcopter That Disassembles Into Two Bicopters Mid-Air

Motivated by the flight ability of severely underactuated rotorcraft, we introduce a transformable quadcopter—SplitFlyer Air. The novel vehicle consists of two bicopter modules, each equipped with only two propellers and capable of position-controlled flight. Despite the notable difference in their flight regimes, the robots, in both the bicopter and quadcopter configurations, can be modeled and controlled by a single framework. In the flight experiments, an undocking mechanism with preloaded elastic energy was designed and employed to assist SplitFlyer Air to disassemble autonomously. The catapult-inspired mechanism provides initial yaw rates for the bicopters, accelerating them to reach their hovering states without losing stability or substantial altitude. Thanks to the developed controller and devised mechanism, the transformation flights can be reliably achieved. The ability to disassemble mid-air shows promise for search and rescue missions or other swarm applications as it allows the flock size to adaptively grow on demand.