Maneuvering Model for Ship Dynamic Positioning

Dynamic positioning systems rely on feedforward control algorithms. Without these algorithms, actuators respond with a delay relative to the ship’s motion, resulting in inadequate control of the vessel. A ship is dynamically positioned at zero forward speed, and the motions involved in maintaining its position are small, leading to relatively subtle actuator responses. Additionally, an effective dynamic positioning system minimizes actuator usage. For these reasons, it is reasonable to neglect interactions between the ship and actuators to achieve faster simulations. In this chapter, we present a simplified @maneuvering model for the dynamic positioning of over-actuated ships. The ship in focus is a twin propeller twin rudder ship with two-stern and two-bow thrusters. A modular mathematical model is used, with external disturbances modeled through empirical relations that account for irregular seas. The proposed model, along with its subfunctions, has undergone extensive testing for consistency, and its reliable performance has been confirmed.