RIASSUNTO
ABSTRACT:
In this article the author established the mathematical model of system identification of composite trimaran rolling motion model based on the genetic optimization algorithm, using VB language to write the recognition software, designed and manufactured a composite trimaran test model, doing the free rolling decay test, then completing the rolling motion system identification according to the test data, and got the rolling motion equation which will be used to do the forecast. The results of the forecast can well match with the test results, so we can confirmed that the feasibility of this set of identification method, laid the foundation for other sway motion research of composite trimaran.
INTRODUCTION
In recent years, various kinds of new ships which have good seakeeping properties have gradually become the hot spot of the research. If we see the ship hull as a rigid body and do not consider the situation of the coupling of the shaking movements then the complex motion can be divided into six motions including rolling, pitching, yawing, surging, swaying and heaving, in which the rolling movement is the most dangerous. Previous research on the seakeeping mostly paused in the stage of theoretical research, the introduction of strip theory mostly promoted theoretical analysis of the shaking movements, the practice proved that the strip theory can effectively solved the problems of pitching and surging, but in the calculation of the rolling, the accuracy is not enough, especially in the process of solving the damping moment during the rolling motion. In the model test analysis, the application of system identification has a long history. In recent years, identification technology has constantly been used in identifying the ship hydrodynamic derivatives and establishing the mathematical model of maneuvering motion, which has obtained considerable progress so far.