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

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