Backstepping based nonlinear PI for attitude stabilisation of a quadrotor: From theory to experiment

Based on the Euler angles parameterization, a new method for the attitude control of a vertical take-off and landing (VTOL) quadrotor aircraft is proposed. It relies on the combination of the backstepping technique and a nonlinear robust PI controller. The integral action gain is nonlinear and based on a switching function that allows a robust behaviour for the overall control law. One of the strengths of the proposed approach is its robustness with respect to plant parameters uncertainties. The proposed approach has been tested in simulation and in real time and shows good performance.