An adaptive backstepping sliding mode method for flight attitude of quadrotor UAVs.

To overcome nonlinear and 6-DOF (degrees of freedom) under-actuated problems for the attitude and position of quadrotor UAVs, an adaptive backstepping sliding mode method for flight attitude of quadrotor UAVs is proposed, in which an adaptive law is designed to online estimate the parameter variations and the upper bound of external disturbances and the assessments is utilized to compensate the backstepping sliding mode control. In addition, the tracking error of the design method is shown to asymptotically converge to zero by using Lyapunov theory. Finally, based on the numerical simulation of quadrotor UAVs using the setting parameters, the results show that the proposed control approach can stabilize the attitude and has hover flight capabilities under the parameter perturbations and external disturbances. [ABSTRACT FROM AUTHOR]