An Over-Actuated Multi-Rotor Aerial Vehicle With Unconstrained Attitude Angles and High Thrust Efficiencies

Abstract

Fully-actuated multi-rotor aerial platforms are receiving increasing research interests for the capability of six degree-of-freedom (DOF) motions such as hovering at non-horizontal attitude angles. Existing real world hardware and experiments have demonstrated such capability for a limited range of angles. This letter presents an aerial platform that achieves maneuvering at arbitrary attitudes with uniformly high thrust efficiencies. We propose a novel vectoring thrust force actuator by mounting a regular quadcopter on a passive mechanical gimbal mechanism. The UAV platform achieves full six-DOF motion with redundancies from four of these vectoring thrust actuators. We present the hierarchical controller, which generates high-level virtual wrench commands, allocations to actuators, and low-level actuator controls. We demonstrate the first real-world experiments of any pose maneuver over 360 degrees without requiring unwrapping rotations.