Direct Backstepping Method for Adaptive Nonlinear Depth Control of an AUV

Abstract

This paper presents a direct backstepping method for depth control of an autonomous underwater vehicle (AUV) whose diving dynamics is in a certain non-affine pure-feedback form. Moreover, because of the highly nonlinear characteristics of dynamics of general underwater vehicles, certain unknown-bound unstructured uncertainty terms are also considered. Proposed control scheme can guarantee the semi-global uniformly ultimately bounded (SGUUB) property of the closed-loop control system.