Output feedback dynamic surface controller for quadrotor UAV with actuator dynamics

In this work, we develop an output feedback altitude-attitude controller for quadrotor UAV in the presence of uncertainties in UAV and actuator dynamics. Controller design for the quadrotor UAV is a difficult task due to its uncertain nonlinear dynamics. Unlike most previous works, we also consider uncertain actuator dynamics into the model construction of the UAV. For state estimation, a nonlinear observer using neural networks is designed. For the controller, the dynamic surface control technique has been used, which has the advantage of less complexity as compared to the conventional backstepping technique. The closed loop stability is proved using Lyapunov stability analysis. Unlike previously published techniques, we do not assume actuator signals are available for measurement in the observer/controller design. Simulation results are presented to demonstrate the effectiveness of the controller in presence of uncertainties in quadrotor UAV and actuator dynamics.