Integrated guidance and control design for automatic landing of fixed-wing unmanned aerial vehicle

A novel integrated guidance and control (IGC) approach is proposed for the landing of a fixed-wing unmanned aerial vehicle (UAV). In this approach, the sliding-mode variable structure control (SMVSC) and the active disturbance rejection control (ADRC) are combined in the structure of the dynamic surface control. A 6-DOF model of the UAV and the model of the relative line of sight (LOS) between the UAV and the target are built. The integrated guidance and control is designed under the dynamic surface control framework with sliding-mode variable structure control. By introducing ADRC technique to the design, we raise the system robustness against the uncertainties in the unmodeled parameters and the external disturbances. The ADRC also suppresses the vibration of sliding-mode variable structure control. This control approach enables the UAV to smoothly fly to the target point, while satisfying the constraints on the landing LOS angle. The design philosophy and modes of thought are described in details. Finally, simulation results are presented to illustrate the effectiveness of the control strategy.