Finite-time observer based accurate tracking control of a marine vehicle with complex unknowns

In this paper, a finite-time observer based accurate tracking control (FO-ATC) scheme is addressed for trajectory tracking of a marine vehicle (MV) with complex unknowns including unmodeled dynamics and disturbances. Main contributions are as follows: (1) An accurate tracking control (ATC) scheme is first proposed for a nominal MV tracking system with known dynamics, such that global finite-time stability of can be ensured to achieve fast convergence and precise tracking performance; (2) To exactly attenuate external disturbances, a finite-time disturbance observer (DO) is incorporated into the ATC framework, and establishes the DO-based ATC (DO-ATC) scheme which therefore produces strong disturbance rejection in addition to accurate trajectory tracking; (3) Aiming to precisely identify completely unknown dynamics together with external disturbances, simultaneously, a finite-time unknown observer (UO) is further created within the ATC approach, and thereby contributing to the UO-based ATC (UO-ATC) scheme which eventually achieves accurate trajectory tracking of an MV with fully unknown dynamics under harsh marine environment. Simulation studies and comprehensive comparisons are exhaustively provided to demonstrate the effectiveness and superiority of the proposed ATC schemes.