It is required for the autopilot flight-controller design of a fixed-wing Unmanned Aerial Vehicle (UAV) to track a predetermined path. In addition, it is required to be robust with respect to environmental disturbances especially wind, since its magnitude is comparable to the UAV speed. In this paper, the modified PID (PI-D) control algorithm is utilized to design an autopilot flight controller for the Aerosonde fixed-wing UAV.
Flight controllers based on the PI-D control algorithm are designed for controlling the altitude and the speed of the UAV. In order to verify the effectiveness and the robustness of this flight controller, it is compared with the genetically tuned traditional PID flight controller. The simulation results based on the Aerosonde UAV model confirm the effectiveness and robustness of the proposed modified PID flight controller. The simulation results show also the capability of the designed approach and its very satisfactory performance with good stability and robustness against external wind disturbance.