Nonlinear output feedback controller design for tracking control of ODIN in wave disturbance condition

This paper presents the design of a nonlinear controller for tracking control of a spherical autonomous underwater vehicle (AUV), named as Omni-Directional Intelligent Navigator (ODIN) operating in shallow water area. When the AUV operates in shallow water environment, significant disturbance due to the wave motion will be introduced into the position and heading of the marine vehicles. It is critical to obtain the knowledge of the wave information or the wave induced disturbance information to reduce the reaction of the controller to this wave motion. In this paper, an observer is designed to estimate the shallow water wave motion, the low frequency motion and bias disturbance by using only the position and heading measurement. A nonlinear output feedback controller is derived based on the developed observer using the observer backstepping technique. The globally exponentially stability (GES) of the whole observer and controller system is proved be Lyapunov stability theory. A set of simulations is carried out to test the performance of the proposed observer and controller for tracking control of ODIN.