Adaptive Fuzzy Attitude Sliding Mode Control for a Quadrotor Unmanned Aerial Vehicle

This paper investigates the problem of attitude stabilization of a quadrotor unmanned aerial vehicle (UAV) in the presence of parametric uncertainty, modeling uncertainty, control input saturation and external disturbance. A fuzzy logic system (FLS) is used to approximate unknown nonlinear function, which consists of parametric uncertainty and modeling uncertainty of quadrotor system. To compensate for control input saturation, a second-order auxiliary system is constructed to reduce the amplitude of the designed control signal. Furthermore, two adaptive fuzzy sliding mode control techniques are proposed to achieve attitude tracking of a quadrotor, where two disturbance rejection strategies are developed. The stability of closed-loop system is proved by Lyapunov theory. The defined tracking error is guaranteed to converge to a neighborhood of zero and the transient bound of real tracking error is derived. The simulation is carried out to illustrate the effectiveness of the proposed method.