Non-linear control algorithm for the four rotors UAV attitude tracking problem

This paper deals with the design and implementation of the nonlinear control algorithm for the attitude tracking of a four-rotor helicopter known as quadrotor. The choice of this algorithm, which is based on the Backstepping sliding mode technique with adaptive gain, was justified by the fact that it ensures robustness with respect to modelling errors and external disturbances while reducing the chattering phenomenon caused by the sign function in the first order sliding mode based controllers with fixed gains. In order to show the effectiveness of the controller, experimental tests were carried out on a quadrotor. The obtained results show good performance of the proposed controller in terms of stabilisation, tracking and robustness.