A New Disturbance Attenuation Control Scheme for Quadrotor Unmanned Aerial Vehicles

This paper addresses a difficult problem of high-accuracy control for quadrotor unmanned aerial vehicles (UAVs) subject to external disturbance force and unknown disturbance torque. An observer-based full control scheme is presented. In the strategy, two observer-based estimators are first designed to estimate external disturbance force and torque, respectively. With the application of the precise estimation value, a nonlinear tracking controller is then proposed with compensated disturbance. It is shown by the Lyapunov stability analysis that the entire controller-observer system is asymptotically stable. The key feature of the scheme is that it not only has the superior capability to attenuate unknown external disturbance torque and external force generated by the wind, but also it is able to achieve full control (i.e., six degrees-of-freedom) of the quadrotor UAVs with position and attitude successfully controlled. The effectiveness of the approach is verified on a quadrotor UAV example.