Filter-based adaptive backstepping attitude control for multi-rotor UAVs with parametric uncertainty, external disturbance and input saturation

In this paper, the attitude control problem of uncertain multi-rotor unmanned aerial vehicles (UAVs) subject to input saturation and external disturbance is considered. First, by introducing a set of low-pass filters, filter-based estimators are utilized for compensating parametric uncertainties to achieve good estimation. Second, a full-order auxiliary system is constructed, which integrates the functions of removing the command filtered error between virtual control and filtered virtual control as well as the deviation between the unsaturated input and the saturated input. In order to deal with the external disturbance more effectively, a filter-based disturbance observer and an adaptive bounding law are developed to suppress it. Simulation results applied to an octorotor system and experimental results applied to a quadrotor system verify the control performance of the proposed method under different conditions.