An Ultralight Air-Ground Vehicle Capable of Sustained Amphibious Maneuverability and Bio-Inspired Modality Transition

This letter presents a 5.2g ultra-lightweight air-ground vehicle capable of passive stable flying and terrestrial cruising. Such a design proposes a passive stability layout, including a single-axis rotor, film dampers, and a stabilizer bar. The advantageous synergy between the rotor and the passive stability components significantly reduces the mass required for stable flight control, representing only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$4.2 \%$</tex-math></inline-formula> of the total vehicle weight. Overcoming challenges posed by low Reynolds number flight, the vehicle achieves stable flight without the added weight of extra sensors, actuators, and control surfaces. A turtle shell-inspired frame has been adopted to enable terrestrial self-righting functionality, performing seamless conversion during the air-ground mode switch. Experimental validation confirms the effectiveness of the proposed passive stabilization design. The tested vehicle demonstrates 330s stable flight with just 5.2g total weight. In addition, the bio-inspired turtle shell version successfully achieves self-righting and validates the capability of air-ground mode transition. The proposed vehicle shows the robustness of air-ground maneuvering and mode switching, promising to broaden the applications in complex environments.