Sliding mode control for a small coaxial rotorcraft UAV

This paper presents a nonlinear control based on sliding mode control (SMC) for the position and the attitude tracking control of a small coaxial-rotor UAV subjected to uncertainties and aerodynamic disturbances. The dynamical motion equations are obtained through the Newton-Euler formalism. Firstly, the dynamical model is divided into a fully actuated subsystem and an underactuated subsystem. Secondly, a controller of the fully actuated subsystem is designed through a sliding mode control controller with integral term. A controller of the underactuated subsystem is designed via the sliding mode control (SMC), for this subsystem, the sliding manifold has four coefficients. The flight controllers are derived by using Lyapunov theory, which guarantees that all system state trajectories reach and stay on the sliding surfaces in finite time and compensate the modeling uncertainty and external disturbances. Simulation results are presented to corroborate the effectiveness and the robustness of the proposed control method.