Controlled course-keeping simulations of a ship under external disturbances

A Simulink code for numerical simulation of ship manoeuvring is developed based on the appropriate differential equations. Both the Abkowitz and MMG models are implemented as choices according to the available hydrodynamic particulars of a given ship. Reliability of the developed code is assessed by performing the turning and zigzag tests for two different ships, employing the Abkowitz and MMG models in turn according to the available characteristics. As a field study, real time records of the routes followed by a passenger ship crossing the Strait of Istanbul under the disturbing effect of a lateral current were made. One of the vessels tested was autopiloted by a classic PD and a fuzzy-like PD controller separately, guiding the ship to a target destination under cross-current as in the Strait of Istanbul. Performances of these controllers in comparison with the human piloting of the field observations reveal that under disturbing current effects both controllers provide relatively shorter travel paths and the fuzzy-like PD controller stands as a better choice between the two.