A Quadrotor With a Passively Reconfigurable Airframe for Hybrid Terrestrial Locomotion

Despite efforts to circumvent and alleviate the impact of a mid-flight collision, it remains extremely challenging to safeguard a multirotor vehicle when it operates in cluttered environments. In this work, we introduce a flying robot with the ability to roll through a gap narrower than its diameter to prevent a possible aerial collision entirely. The novelty of the proposed design lies in a simple passive mechanism that redirects the propelling thrust for the terrestrial operation without the need for extra actuators. As a result, the robot remains compact and lightweight. Furthermore, to overcome the underactuation associated with the passive structure, the transitions between flight and rolling are accomplished with a highly dynamic maneuver. In the experimental demonstration, the robot seamlessly switched between the aerial and terrestrial locomotion to safely negotiate a 10-cm opening.