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Circular Trajectory Tracking by Lightweight UAVs in the Presence of Winds

Achudhan Sivakumar, Colin Keng-Yan Tan


Maintaining accurate flight path tracking in the presence of winds is a major challenge for very light and micro UAVs weighing less than 20 kg, making applications like searches of fields and accurate localization of targets difficult. Methods that depend on measuring wind speed and direction on board the UAV do not generally work well due to other wind currents and turbulence caused by airflow over the aircraft body, and by propeller wash. This paper presents a Dynamic Cell Structure (DCS) based flight control system capable of enhancing lateral stability of aircrafts in order to track a circular trajectory accurately. The aim of the control system is to generate control surface deflections such that precisely sufficient roll is produced to keep the aircraft along along the desired circle. The DCS is trained using multiple PID-based control systems, each tuned for different wind speed situations. Three important changes have been made to the original DCS learning algorithm to increase the speed and accuracy of offline learning on the DCS. We implement the control system over the Arudpilot Mega autopilot. The proposed control system is first tested using hardware-in-the-loop simulations on the XPlane 9 simulator and compared against the performance of the baseline PID system on the Arudpilot Mega. We also conduct real flight tests using the proposed control system as well as the baseline PID system on a 1.63m wingspan foam aircraft. Results showing the achieved performance improvement in both simulations as well as real tests are presented.

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