Integral Active Finite-time Disturbance Rejection Control for Attitude Tracking of Quad-rotor

For the attitude tracking of quad-rotor system in the presence of disturbances, an integral active finite-time disturbance rejection control method is presented in this paper. Specifically, first, based on a second-order attitude model of quad-rotor in the absence of disturbances, a finite-time attitude control algorithm under is proposed. At the second step, considering the existence of disturbances including constant disturbances or time-varying disturbances, a disturbance observer is designed to estimate the disturbances. Finally, using the idea of active disturbance rejection, the disturbance is directly compensated through the control input channel in the case of constant disturbance. In the case of time-varying disturbance, an integral sliding mode control method is employed here to handle the disturbance estimating error. Rigorous theoretical analysis is provided to prove that the the desired attitude can be tracked in a finite time no matter what kinds of disturbances. Simulation results are given to verify the effectiveness and advantages of the the proposed integral active finite-time control method.