Design and Experimental Verification of a Multirotor Aircraft

Conventional multirotor aircrafts are underactuated, while the translational and rotational motions are strongly coupled. These features severely limit the maneuverability of the aircraft. Therefore, a multi-rotor aircraft is designed, which can perform omnidirectional motion, vector thrust control flight and tilt-hovering. A regular tetrahedron structure is adopted, and four tilting rotor modules are mounted at the four vertices of the tetrahedron. Each tilting rotor module can provide the vector thrust, so the attitude control and the position control of the aircraft are decoupled owing to the structure, and the aircraft is thus capable of the all-attitude trace tracking in 3D space. In addition, an attitude controller based on quaternion is designed in order to avoid the singularity caused by Euler angle control. The controllability principle is used to analyze the controllability of the aircraft when a rotor malfunctions, and the aircraft demonstrates a higher fault tolerance than the conventional ones. In the prototype experiment, the aircraft's large-angle complex maneuver and the vector thrust control flight capability are tested, and the maximum tilting angle in tilt-hovering is 70°. The experimental results show that the aircraft has a higher maneuverability than the conventional quadrotors.