A combined control system with roll reduction and track keeping for the ship moving in waves

In this paper, a hydrodynamic numerical model with a combined control system is developed to simulate a ship steering in waves. The combined control system includes the PD controller and the sliding mode controller. By way of the rudder operation, the PD controller integrated with a line-of-sight (LOS) guidance system is used to control the track keeping, whereas the sliding mode controller is mainly chosen to reduce the roll motion. Different heading angle, wave height, wavelength, and initial speed are selected to investigate the combined control ability of the auto-pilot system. From simulation results, we find that this combined control system indeed works well, either for the ship roll motion reduction or for the ship track keeping in waves.