Design and Implementation of a Multimodal Tilt‐Rotor Unmanned Aerial‐Aquatic Vehicle

ABSTRACT The unmanned aerial‐aquatic vehicle (UAAV) can be operated in both air and water for scientific and engineering applications. However, the endurance and maneuverability of the UAAV are challenged by the complex multi‐domain tasks. Inspired by the locomotion modes of the tilt‐rotor unmanned aerial vehicle (UAV) and the hybrid underwater glider (HUG), the design and implementation of a multimodal tilt‐rotor UAAV are presented in this paper. This UAAV can repeat trans‐domain and move in both air and underwater. To minimize configuration redundancy and weight of the vehicle, the amphibious structures are implemented, which include a waterproof air tilt‐rotor to provide vector pull for underwater propulsion, a movable buoyant tailplane to adjust the pitch angle for underwater gliding, a distributed variable buoyancy system (DVBS) to control buoyancy, and the hollow wings with a 10° dihedral angle to assist water exit. The vehicle prototype was fabricated, and tested in ocean environments, lakes, and high‐visibility pools. The results demonstrate that the vehicle can perform controllably and repeatedly trans‐domain under disturbed conditions, and the combination of efficient and flexible locomotion modes can enhance the endurance and maneuverability of the vehicle in multidomain environments. In particular, the underwater endurance of over 12 h, and the underwater attitude response rates improve by over 100%. Moreover, the vehicle's weight is decreased by over 39% owing to the implementation of amphibious structures.