1 Introduction
At present, Autonomous Underwater Vehicle (AUV) has been widely used in marine resources exploration, seafloor mapping, biological detection and so on [1]–[3]. AUV is subject to model uncertainties and unknown external disturbances in the marine environment. Model uncertainties are mainly caused by the uncertain body parameters, variable hydrodynamic parameters and unmodeled dynamics. Fur-thermore, the unknown external disturbances mainly contain the wind, waves and ocean currents [4], [5].