A Double-layer Fuzzy Controller for the Altitude of Fixed-wing Unmanned Aerial Vehicles

The altitude control of miniature fixed-wing unmanned aerial vehicles(UAVs) faces with many difficulties because of the strongly coupling dynamics and high external disturbances. To deal with these issues, this paper proposes a fuzzy logic based altitude control scheme. Specifically, a double-layer fuzzy controller is developed, taking the altitude error, the measurements of the roll angle, the pitch angle and the speed of the UAV as inputs, to compensate the control performance with an additional pitch angle and speed when the UAV has large roll angles and/or sudden speed losses in winds. The member functions of the fuzzy controller are designed carefully according to numerous simulation experiment data. The effectiveness and anti-disturbance of the proposed controller are validated by a series of high-fidelity semi-physical simulations.