Abstract: Due to its underwater navigation and aerial flight capabilities, water-air amphibious drones have entered people's perspectives in recent years. Aiming at the problem that existing water-air UAVs cannot play a role in complex scenarios (such as water-air interface, indoor, etc.), a water-air amphibious UAV combining rotorcraft, fixed-wing and folding wing mechanism is proposed. This study design a three-rotor mechanism based on tilting motor and a folding wing mechanism based on servo control, and use the tilting mechanism and folding wing mechanism to realize the mode switching between fixed wing and rotor to achieve the flight state of birds. For birds in nature, wing control is very important. In the air, most birds use the folding of their wings to control the steering and altitude of flight. When birds are about to enter the water or have already entered the water, many birds enter the water or move underwater by retracting their wings completely to reduce the resistance area. This study imitate the principle of bird winging to design folding wing structure and tilting rotor structure, so that water-air amphibious UAVs can realize the free transformation of rotors and fixed wings. In order to verify the reliability of the structure, theoretical analysis and simulation experiments are carried out on the UAV structure, and complex scene experiments such as air and underwater are carried out, and the experimental results show that the UAV can realize the free switching between rotary wing and fixed wing in the air, and cross-media flight of the water-air interface under water, which verified the feasibility and effectiveness of the scheme.

Key words: transmedium UAV, tilting rotor, foldable wing design