Nonlinear Adaptive Bottom-Following Control of an AUV in the Presence of Ocean Currents

This paper addresses the bottom-following control problem of an underactuated autonomous underwater vehicle (AUV) in the presence of ocean currents and model parameters uncertainties. The Serret-Frenet frame is used to describe the bottom following of the AUV. An extra degree of freedom for controller design is introduced. The extra degree of freedom makes the virtual AUV can regulate its velocity along with the real AUV. Based on Lyapunov theory and backstepping techniques, a nonlinear adaptive control law is derived. The control law yields convergence of the AUV to the desired path asymptotically. Simulations results show the effectiveness and robustness of the derived controllers.