Heading control for turret-moored vessel in level ice based on Kalman filter with thrust allocation

This paper mainly focuses on the heading control of a position-moored vessel operating under level ice regime. A dynamic ice simulator interconnecting the vessel motions with the ice dynamics is used for the design of the heading control system. The strategy is to ensure that the vessel is kept at an appropriate position within the safe limits. Using a heading controller based on a Kalman filter, the desired control force is computed to counteract the environmental disturbances. A thrust allocation method is developed to go with the heading controller. To keep the ice forces to a reasonable level, the moored vessel should be aligned with the ice drift direction and small angles up to 15A degrees in changes on heading against the ice flow could be possible. Therefore, heading control of a moored vessel exposed to level ice with drift angle 0A degrees and 15A degrees is simulated since the dynamic positioning system needs to resist ice yaw moments and lateral ice forces on the hull. The simulation indicates that the proposed control strategy performs satisfactorily for a moored vessel in level ice.