Surge-varying LOS based path following control of underactuated marine vehicles with accurate disturbance observation

Suffering from complex unknown disturbances, a novel surge-varying LOS (SVLOS) based path following control scheme of underactuated marine vehicles (UMVs) is proposed in this paper. Main contributions are as follows: (1) The surge velocity guided with cross-track error is incorporated into previous line-of-sight guidance laws, and thereby significantly enhancing robustness and agility of the guidance system; (2) Complex unknown disturbances are compositely estimated by the constructed finite-time disturbance observer (FDO), and the observation errors are ensured to be zero in a finite time; (3) Robust surge and heading tracking controllers based on the FDO design and backstepping technique are developed so that reference surge and heading can be exactly tracked with complex unknown disturbances. Simulation studies are conducted to demonstrate the effectiveness and remarkable performance of the proposed FDO-SVLOS scheme.