Fast and Accurate Trajectory Tracking Control of an Autonomous Surface Vehicle With Unmodeled Dynamics and Disturbances

In this paper, fast and accurate trajectory tracking control of an autonomous surface vehicle (ASV) with complex unknowns, including unmodeled dynamics, uncertainties, and/or unknown disturbances, is addressed within a proposed homogeneity-based finite-time control (HFC) framework. Major contributions are as follows: first, in the absence of external disturbances, a nominal HFC framework is established to achieve exact trajectory tracking control of an ASV, whereby global finite-time stability is ensured by combining homogeneous analysis and Lyapunov approach; second, within the HFC scheme, a finite-time disturbance observer (FDO) is further nested to rapidly and accurately reject complex disturbances, and thereby contributing to an FDO-based HFC (FDO-HFC) scheme, which can realize exactness of trajectory tracking and disturbance observation; and third, aiming to exactly deal with complicated unknowns including unmodeled dynamics and/or disturbances, a finite-time unknown observer (FUO) is deployed as a patch for the nominal HFC framework, and eventually results in an FUO-based HFC (FUO-HFC) scheme, which guarantees that accurate trajectory tracking can be achieved for an ASV under harsh environments. Simulation studies and comprehensive comparisons conducted on a benchmark ship demonstrate the effectiveness and superiority of the proposed HFC schemes.