Robust Nonlinear Control for Path Tracking of a Quad‐Rotor Helicopter

This paper presents a nonlinear robust control strategy to solve the path tracking problem for a quadrotor unmanned aerial vehicle. The main objective is to design controllers that provide certain required performances during the quadrotor flight, such as null tracking error and robustness in the presence of sustained external disturbances affecting the six degrees of freedom, parametric uncertainties, and unmodeled dynamics. The control structure is performed through a nonlinearH ∞controller to stabilize the rotational movements and a control law based on the backstepping approach with integral action to track the reference trajectory. Simulation results are carried out to corroborate the effectiveness and the robustness of the proposed strategy.