A Method to Optimize Steering Performance of Conventional Ship Autopilots

A method allowing a priori optimization of fixed structure steering controllers is presented. The technique is based on the second method of Lyapunov, and allows optimization of the controller parameter values to a predefined quadratic index of steering quality. The design methodology involved is applied to different controller structures using a 250,000-dwt tanker as an example. The resulting performance is compared to that achievable for a standard setting conventional autopilot on the same ship, using frequency domain analyses. The results presented suggest that the method has the potential to result in improved steering performance.