Study On The Mathematics For The Point Of The Last Minute Action

It is the purpose of navigation to convey cargo and passenger to the destination safely and effective . This system is called navigation system. It includes ship ,environment and navigation method .Research on collision avoidance is studying around this three factors in many ways and many directions."Rules" requires ships to abide by every terms , and there are a lot of specific , comprehensive terms about determination of collision risk .but , there is not a rigid concept about "risk of collision " .Its very important .So it is difficult to establish the concept of the point of the last minute action .The point of the last minute action is a important method to evaluate the ships collision risk .It is a very important concept not only in navigation practice area , but also in the intelligent decision ?making system for ship collision avoidance .when from any cause , the two ships approach so close that collision can not be avoided by the action of the give梬ay vessel alone , the captain of the stand 梠n vessel should take such action as will best aid to avoid collision . This is her power and her obligation of the stand ~ on vessel. but the problem is how to decide the limit point .In this field much progress has been made in recent years . Author processed a new method of establishing the point of the last minute action.The point of the last minute action is a dynamic model. The factors affection includes : ship maneuvering ,ships speed ,measure ,inencounter situation , behaviour experienced ,natural etc. First of all, these factors should be put in order according to the administrative structure .These factors are relativity experienced , fuzziness . Ship maneuvering safety is difficult to quantity , so in this paper , such fuzziness are analysed and described by the theory of fuzzy mathematics to establish the model of comprehensive evaluation .The concept of ship domain has been consideration .Ship domain is combined with decision梞aking system for ship collision avoidance .To check and confirm to rationality ,in this paper, a set of simulation on radar simulator are given . The validity and practicability of the method are proved .