Disturbance Observer-Based Tracking Controller for Uncertain Marine Surface Vessel

In this study, a novel control framework is proposed to improve the tracking performance of uncertain marine vessels which work in enhanced sea states. The strategy based on incorporating fixed-time nonlinear disturbance observer (FTNDO) convergent backstepping control. More specifically, FTNDO developed reconstruct total uncertainties due system uncertainty and unknown time-varying exterior disturbances. comparison with existing observers, guarantees that estimation errors will converge origin within predefined time even if initial tend toward infinity. This feature quite important closed-loop stability analysis as separation principle does not hold systems. Besides, it require restricting assumption upper bound lumped or its derivative has be bounded known. A compensation part then designed make finite regardless errors. by means estimated signal applied totally reject uncertainty. global stabilization investigated through Lyapunov criterion. Numerical simulation results conducted an surface vessel confirm superior efficiency planned method observer-based strategies.