Hierarchical fuzzy/Lyapunov control for horizontal plane trajectory tracking of underactuated AUV

A new hierarchical closed loop fuzzy control system for horizontal plane trajectory tracking of underactuated Autonomous Underwater Vehicles (AUV) is presented. A model for the AUV is formulated introducing a polar coordinates transformation for the velocities in the body fixed frame. It is employed to control the unactuated sway direction, the longitudinal position and the yaw by using the surge force and the yaw torque only. The highest level control is developed by employing a fuzzy inference system for obtaining the guidance control laws. The properties of the fuzzy system ensure forward surge velocity, fast convergence and Lyapunov´s stability of the motion errors. A new low level kinetic controller is presented for ensuring that the actual velocities of the AUV converge to the fuzzy guidance control laws. The control algorithm efficiency is confirmed through simulation experiments in a Matlab environment.