Modeling and Simulation of the Roll Motions of a Ship

At the Control Laboratory of the Electrical Engineering Department of Delft University of Technology much research has been carried out during the last 15 years in the field of ship control systems, with the main emphasis on automatic steering of ships. At the moment, the research is concentrated on the design of an autopilot which uses the rudder not only for course keeping but also for roll stabilization, where mostly stabilizing fins have been used up to now. Modeling experiments were carried out and based on their results a simple model of a ship describing the transfer between the rudder and the yaw motions was obtained. The model was subsequently used to design a Rudder Roll Stabilization, RRS, autopilot.The autopilot was extensively tested with two types of digital computer simulations and their results were verified with scale-model experiments in open water and full-scale trials with a ship of the Royal Netherlands Navy. The experiments demonstrated that an RRS autopilot, designed and tested by means of digital computer simulations, is able to realize roll reduction during full-scale trials comparable to that achieved by computer simulations. This makes it attractive to examine new ship designs with respect to the applicability of an RRS autopilot by means of computer simulations. This paper reports the results of these experiments.