Aiming at the problem of the point stabilization control of a benthic autonomous underwater vehicle (AUV) under unknown disturbances and uncertainties, a fixed-time backstepping controller based on a fixed-time extended state observer (FTESO) is designed.

First, according to the point stabilization tracking error model of AUVs, a new FTESO is proposed to estimate the unknown disturbances and unmeasurable velocity, and the observation error can be converged to zero in a fixed time. Based on the above observer, a fixed-time point stabilization controller is then designed using the backstepping method. Finally, by adding a first-order filter, the inherent complexity explosion of the backstepping controller is solved, and the semi-global fixed-time uniform ultimate boundedness of the closed-loop system is proven by Lyapunov stability analysis.

The feasibility and superiority of the proposed scheme are verified by simulation experiments.

The results show that the proposed scheme can solve the point stabilization control problem of a benthic AUV affected by unknown disturbances and uncertainties, and improve the convergence time of the control system.