Adaptive sliding mode finite-time control for quadrotor UAV with unknown external disturbances and drag coefficients

For the quadrotor unmanned aerial vehicle (UAV) system in the presence of unknown drag coefficients and unknown external disturbances, a new adaptive sliding mode finite-time tracking control algorithm is presented. The whole control system can be divided into two subsystems, that is, position subsystem and attitude subsystem. And, by the attitude extraction algorithms, the two subsystems are connected each other. The adaptive sliding mode finite-time control methods are designed for both position subsystem and attitude subsystem. In order to estimate the external disturbances of position subsystem, finite-time disturbance observers are designed. At the same time, a new adaptive method is used to deal with the unknown drag coefficients. In addition, the limitation of knowing the boundaries of the external disturbances of attitude subsystem is cancelled by using adaptive technology. The position and attitude tracking errors of quadrotor UAV are proved to be asymptotic stability in finite time by using Lyapunov theory. Finally, simulation results are given to verify the effectiveness of the proposed finite-time control method.