Robust Tracking Controller for Quadrotor Based on Flatness and High Gain Observer

This paper proposes a robust tracking controller based on the state estimation for a quadrotor. Using the differential flatness theory, it is demonstrated that the quadrotor model can be changed to a linearized form which facilitate the creation of a state feedback controller. Since some state vectors of the obtained linearized model cannot be measured directly, a high gain observer is implemented to estimate them. After that, utilizing the estimation state obtained by the latter observer, a new guidance law is developed for the quadrotor enabling a robust tracking to the desired trajectory despite the existence of unmesurable states. The numerical simulation of the quadrotor system is done in order to evaluate the performance of the robust tracking control scheme.