An intermediary quaternion-based control for trajectory following using a quadrotor

This work uses the intermediary quaternions in the design of a backstepping control technique with integral properties in order to perform an autonomous trajectory tracking using a quadcopter vehicle. Nowadays, in order to determine the orientation of a vehicle, most of the inertial systems of aircrafts can give directly the rotation matrix and taking advantage of this fact, the intermediary quaternions can be determined in a simple way from this matrix. Moreover, one specific orientation corresponds to only one intermediary quaternion and this helps to cope the unwinding phenomenon presented when working with the classical quaternions. The proposed control algorithm is validated numerically and experimentally when the quadrotor follows a circular trajectory. In addition, during the simulation part, some external perturbations and white noise were added in order to test the robustness of the algorithm.