Small Fixed-Wing Unmanned Aerial Vehicle Path Following Under Low Altitude Wind Shear Disturbance

The wind shear in low altitude can bring about time-varying and unknown disturbances, which makes small fixed-wing Unmanned Aerial Vehicle (UAV) hard to accurately follow desired curved paths. In this paper, a Vector Field (VF) based curved path following algorithm is designed for UAV to overcome the above difficulties. Firstly, the path following problem is mathematically formulated to give the kinematics model of UAV with constant airspeed. Secondly, the curved path following control laws under both constant and time-varying unknown wind disturbances are designed with VF. A ground velocity estimator is additionally designed to overcome the difficulties of unmeasurable ground velocity, and the Lyapunov stability of curved path following is analyzed. Finally, both simulations and field tests on a real small fixed-wing UAV are carried out to evaluate the algorithm performance in the presence of time-varying and unknown wind disturbances. Verification results demonstrate that the algorithm proposed in this paper outperforms other widely used path following algorithms and can effectively follow arbitrary curved paths.