Path-Following in 3D for Underactuated AUV in the Presence of Ocean Current

In this paper, a nonlinear control strategy is developed to force an under actuated autonomous underwater vehicle to follow a predefined 3D path in the presence of ocean-current and vehicle´s unknown physical parameters. The controller is derived using line-of-sight guidance system and the back stepping technique. The parameter projection techniques are used to estimate the unknown parameters to avoid the parameters´ drift. The path-following errors are proved to be uniformly stable bounded using Lyapunov theory. Numerical simulations are provided to illustrate the effectiveness of the proposed controller.