Robust Attitude Control Scheme for Constantly Spinning Small-Sized Quadrotor in the Presence of Imbalance Characteristics

Unlike normal yaw motion, a constantly spinning quadrotor experiences severe instability while rotating at high angular speeds owing to its imbalancecharacteristics originating from the off-center parts. To resolve this issue, this study proposes a novel composite robust control scheme for a constantly spinning quadrotor, with the aim to achieving omnidirectional sensing by scanning its surroundings with a single field of view limited sensor. The proposed scheme makes use of both offline calibration and online disturbance observation to compensate for the variation in the center of mass and misalignment between the body-fixed frame and principal axis of rotation, respectively. Additionally, the reference inputs are reshaped, or leading in time, to achieve the desired flying direction. It is demonstrated through an experiment that the proposed control scheme compensates well for the effect of the imbalance characteristics of the quadrotor, thus achieving good omnidirectional sensing with more stable rotation.