Fixed-time extended state observer-based trajectory tracking and point stabilization control for marine surface vessels with uncertainties and disturbances

In this paper, a novel output feedback trajectory tracking control scheme is proposed for marine surface vessels (MSVs). A fixed-time extended state observer (FXESO) is developed to estimate unmeasured velocities and lumped disturbances, and their estimation errors converge to the origin in fixed time. Especially, the convergence time of the system is independent of the initial states of an MSV. These lumped disturbances consist of uncertainties and external time-varying disturbances. Considering control accuracy and convergence rate, a finite-time homogeneity control theory (FHC) is employed in the controller design. The proposed scheme can guarantee the tracking errors to converge to zero in finite time. Meanwhile, the point stabilization is considered as a special case of the trajectory tracking, and the superior results can be achieved under the proposed control scheme framework as well. Finally, simulation studies and comparisons demonstrate the effectiveness of the developed control scheme.