Modeling and simulation of ship longitudinal motion

A method of studying hydrodynamic coefficient´s nonlinear adaptive intelligent model was proposed based on ship motion in the sea all-weather situation. On the basis of microtome section theory, giving the hydrodynamic expression of different wave direction. Using optimal stopping method to optimize the radial basis function(RBF), through simulate and research get the real-time controlling model of ship longitudinal motion based on water pool experiment and the analysis of hydrodynamic coefficient of the 442T ship representative sea situation. This model can on-line compute hydrodynamic coefficients of ship longitudinal motion which has irrespective of frequency in any direction, speed and sea situation, so that we can get the on-line all-weather controlling model of ship longitudinal motion. Simulation results indicate that nonlinear coefficient model can be quickly and accurately established by using optimal stopping algorithm of radial basis function. Research on intelligent model was done by different and columns methods: full-samples RBF model, which the maximal relative error is 9.1289% under the arbitrary ocean condition degree, navigating speed and navigate angle; the model´s simulation characteristic get better after classified database, the maximal relatively error of which was 7.9467%; the maximal relatively error down to 4.7873 % because of gradient algorithm introduced and the mixed intelligent model was established in three class by classified data, the maximal relatively error of which was 0.9845%.