Fixed-time disturbance observer-based fixed-time path following control for small fixed-wing UAVs under wind disturbances

In this paper, the three-dimensional path following control problem for small-scale fixed-wing unmanned aerial vehicles (UAVs) subject to external wind disturbances is investigated. A fixed-time disturbance observer is designed to estimate the external wind disturbance. The estimates are then incorporated into the fixed-time integral terminal sliding mode controller such that a composite control scheme is proposed. Under the proposed control scheme, the UAV system not only guarantees a fixed-time convergence rate but also possesses stronger disturbance rejection ability and better robustness. Finally, the effectiveness of this strategy is verified by numerical simulations.