Dynamic positioning of AUVs in shallow water environment: observer and controller design

This paper presents a globally asymptotically stabilizing (GAS) output feedback controller for dynamic positioning (DP) of autonomous underwater vehicles (AUVs) operating in shallow water area. Dynamic positioning vehicle is defined as a marine vehicle which maintains its position to a reference object. An observer is used to estimate the wave velocity, wave motion displacement, vehicle´s velocity, and noise free position and rotation angle information which are used in the output feedback controller. A separation principle which holds for AUV model in this paper is used for stability proof of the closed-loop system. The separation principle is based on recent results of cascaded nonlinear systems and Lyapunov stability theory. The closed-loop system has been illustrated using an AUV and the simulation shows the good performance of the observer and the controller