Attitude Stabilization for a Quadrotor Using Adaptive Control Algorithm

This article investigates the problem of attitude stabilization for a quadrotor unmanned aerial vehicle (UAV) in the presence of parametric uncertainties, control input saturation, and external disturbances. Two robust adaptive control strategies, i.e., bounded adaptive control (BAC) and asymptotical adaptive control (AAC) are developed, respectively, where the construction of saturation auxiliary system and the design of adaptive laws for parameters and disturbance's bound are considered. As a result, the compensation of input saturation, the estimation of physical parameters, and the suppression of external disturbance are achieved. In BAC, the real attitude tracking error is guaranteed to converge to a neighborhood of zero, and its transient performance is constrained to an explicit bounded range. In AAC, the real attitude tracking error is proved to be asymptotically stable, and its transient bound in terms of $L_{2}$ norm is derived by constructing an auxiliary equation, which is a computable bound. The simulation is carried out to verify the robustness and effectiveness of the proposed two control techniques.