An adaptive sliding mode controller based on global asymptotic convergent observer for attitude tracking of quadrotor unmanned aerial vehicles

Abstract

This article presents an adaptive sliding mode controller based on global asymptotic convergent observer for attitude tracking problem of a quadrotor unmanned aerial vehicle under modeling uncertainties and external disturbances. For avoiding the singularity problem, the attitude tracking error equations of a quadrotor with quaternion representation are introduced. For obtaining unmeasured states of the control system, a global asymptotic convergent observer without model-based is presented to estimate. To reject uncertainties and disturbances, a new observer-based controller for the quadrotor is designed by combining adaptive sliding mode control algorithm with time-delay estimation method. The stability analysis shows that the tracking errors of the proposed scheme are uniformly ultimately bounded. Simulation results are carried out to illustrate that compared with the existing controller, the proposed control scheme has better attitude tracking performance and higher robustness to reject the disturbances.