Abstract
In this paper, we investigate the usefulness of active stabilizing fins on ship pitching reduction under varying forward speeds, in varying wave lengths. A 4-meter self-propelled ship model and an electrohydraulically driven stabilizing fin system are used as our experimental system. Pitch angles, pitch rates, and ship forward speeds are measured and feedback to a fuzzy logic controller to calculate the deflection angle of the stabilizing fins. The effects of fin nonlinearity on achievable pitch reduction performance are discussed. It is shown that desired pitch response can only be achieved when the fin is operated in its linear region. The overall dynamic response of the ship approaches her open loop behavior when the degree of nonlinearity is high. This simple analysis to the pitch stablizing system provides basic information to ship designers. Experimental results validate this design guideline.
