Robust state estimation of a quadrotor based on high-gain and sliding-mode observers

In this paper, we investigate the problem of joint states and external aerodynamic disturbances estimation for a quadrotor model. The dynamics of longitudinal and angular velocities are corrupted by unknown time varying disturbances whereas only positions and angles are available for measurements. To overcome the problem of observer matching condition, we generate auxiliary outputs to relax the structural properties of the quadrotor system based a high gain approximate differentiator. The latter estimated signals are used by a first order sliding mode observer to reconstruct both the states and the unknown disturbances of the quadrotor. Numerical simulations are depicted to illustrate the effectiveness and the good performances of the proposed observer.