Abstract: This paper addresses three-dimensional path-following control for fixed-wing unmanned aerial vehicle formations under unknown varying wind with a two-layer guidance and coordination framework. For the guidance layer, a predefined-time predictor-based line-of-sight guidance law is proposed, which estimates horizontal and vertical crab angles induced by wind, and guarantees bounded convergence of both path-following errors and crab angle predictor errors within a designer-chosen time. For the formation coordination layer, based on the novel stipulated-time method, a distributed observer and a consensus law are designed to synchronize the path parameters of all followers with a virtual leader at a precisely prescribed instant, providing each follower with accurate reference position and velocity from that instant onward. Given that the reference speed may exceed physical speed constraints before the convergence instant, an anti-saturation auxiliary system is incorporated to preserve the predefined-time stability guarantee. Comparative simulations against multiple baseline line-of-sight guidance methods and integrated multi-UAV formation tests under various paths and wind conditions validate the proposed approach.

Key words: fixed-wing UAV, predefined-time control, predictor, path following, line-of-sight guidance law, stipulated-time control