| Ship control capability analysis system is one of most important components of ship dynamic positioning system, it can analyze the maximal environmental condition from one direction which the ship can resist at one special propeller configuration using it's own propellers. In this paper, when it comes to ship dynamic positioning system schema argumentation, ship off-line control capability analysis means the control capability when ship propellers have no problem, on the other hand ship on-line control capability analysis means the control capability when ship propellers have problem .Many investigations have been done from foreign countries, for example, some dynamic positioning system development company and relative university have developed software product concerned with control capability calculation, which can offer theoretical basis for dynamic positioning system schema design. The paper first establish wind force,current force and wave force ,at the same time establish wind coefficient model for the general ship based on Isherwood (1972). The paper designs and develops a program based on GA which can estimate both ship off-line control capability and ship on-line control capability. Further more according to propeller configuration establish ship propeller force allocation model, next select GA factor and developed off-line control capability calculation and on-line control capability calculation based on GA. When it comes to off-line GA ,the paper offers the change tendency for maximal fitness,the minimal fitness and the average fitness with the increasing evolution generation, then give relative analysis and explanation. Besides this, the paper show simulated result for both off-line control capability and on-line control capability using Visual c++ on Windows platform, make a comparison between Kongsberg result and the paper's, we can find the difference is small. |
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