ROBUST-CONTROL METHODOLOGY APPLIED TO THE DESIGN OF A COMBINED STEERING STABILISER SYSTEM FOR WARSHIPS/

The consequences of roll motions in ship operations can seriously degr ade the performance of mechanical and personnel effectiveness. To alle viate roll motions many ships are equipped with fin stabilisers. Rudde rs can also generate roll motions which can be harnessed to function i n congress with the fins to accrue enhanced levels of stabilisation. A n integrated rudder and fin stabilisation control strategy is proposed . Rudder roll controllers and autopilots are developed using the H inf inity optimisation technique and their performance compared with the c lassical counterparts. Simulation studies are described that quantify the performance of the various controllers. The level of interaction p resent between the yaw and roll control loops is also examined. The st udy concludes that the overall performance of the H infinity RRS contr oller and autopilot is superior to that of the classical type. The lev el of interaction between the two loops can be suitably modified by va rying the performance weighting functions. The study has concentrated on designing the controllers for frigates of the Royal Navy, however, the approach is suitable to present and future warship design.