Almost global tracking control of a quadrotor UAV on SE(3)

In this paper we present a controller which achieves uniform almost global asymptotic stability of the tracking error dynamics for a quadrotor on SE(3). By considering the tracking control of a quadrotor UAV on SE(3) we avoid singularities of Euler angles and ambiguity of quaternions and by explicitly taking into account the constraint of non-zero total thrust in our controller design, we do not achieve a local result but almost global asymptotic stability of the tracking controller. Second, we consider the position tracking error in the body-frame of the reference UAV. As a result, contrary to most existing tracking controllers, our control action becomes independent of the definition of the inertial frame. We illustrate by simulations that even in the presence of small disturbances and sampled, delayed, and noisy measurements the controller achieves stable tracking error dynamics for which errors converge to some region near the origin.