SAFF-LOS and Dual-Priority Rudder Control for High-Accuracy Path Tracking of Unmanned Sailboats

With the growing demand for zero-carbon ocean observation, unmanned sailboats (USVs) offer a promising solution for long-endurance and low-power marine sensing. However, small-scale platforms are constrained by sail-keel coupling and rely on passive side-slip (leeway β) for lateral force balance, limiting path-following accuracy. Conventional LOS guidance neglects leeway, causing cross-track errors, while rudder control faces strong coupling between force balance and heading tracking. Existing decoupled methods treat leeway as a disturbance, degrading performance. This paper proposes a threelayer leeway-control framework, forming a closed-loop from force balance to path tracking. SAFF-LOS compensates leeway at the guidance level; SKC-DSBC provides equilibrium β_balance DPSH-RFC ensures coordinated control with a 'leeway-first' strategy. Simulations verify improved accuracy and robustness, offering a new paradigm for unmanned sailboat control.