Fuzzy Uncertainty Observer Based Path Following Control of Underactuated Marine Vehicles with Unmodelled Dynamics and Disturbances

For an underactuated marine vehicle (UMV) with unmodelled dynamics and disturbances, a novel fuzzy uncertainty observer based path following control (FUO-PFC) scheme is proposed. Main contributions are as follows: (1) A surge-varying line-of-sight (SVLOS) guidance law is devised innovatively where the guided surge velocity adapts to cross-track error, and thereby significantly enhancing robustness and agility of the guidance system; (2) Unknown nonlinearities including unmodelled dynamics and disturbances are compositely estimated by the constructed fuzzy uncertainty observer (FUO); (3) Robust surge and heading tracking controllers based on the FUO are developed to ensure that tracking and observation errors are uniformly ultimately bounded (UUB). Simulation studies are conducted to demonstrate the effectiveness and remarkable performance of the proposed FUO-PFC scheme.