Robust adaptive ship autopilot with wave filter and integral action

A stable minimum phase transfer function from rudder angle to yaw angle is used to design a globally convergent adaptive ship autopilot. First-order wave disturbances in yaw are filtered by applying a notch filter. Integral action is introduced by augmenting the plant. Global convergence is proven for the total system which includes the observer, the parameter update law, the feedback controller, the notch filter and the integral part of the controller. The simulation results showed that the performance is excellent, even with no a priori knowledge of the ship parameters.