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