Iterative method based on CFD data for the assessment of seakeeping control effects, considering amplitude and rate saturation

An iterative procedure for the frequency domain evaluation of control effects in nonlinear loops is introduced. The article focuses on ship seakeeping control, to attenuate ship motions. There is no model of the ship, only CFD tabulated data. The proposed procedure could be used for design or empirical tuning of a controller. The actuators have angle and rate limits. In the case of a ship, the actuators are submerged moving wings: flaps, fins and T-foil. The control evaluation procedure uses a describing function approach. The paper considers amplitude and rate saturation in series. The results are validated with experiments using a scaled ship in a towing tank facility. Copyright © 2010 John Wiley & Sons, Ltd.