Research On Ship Collision Risk Model Based On Dynamic Environment

In order to be beneficial for ship collision avoidance,IMO(International Maritime Organization)and relevant national organizations have taken a series of measures,such as the proposal of COLREGS,the mandatory various equipment of communication and navigation,the mandatory installation of automatic identification system for large ships,the establishment of VTS.Despite these measures have been taken,ship collision accidents occur from time to time.In 1995,the International Maritime Organization adopted an amendment of SOLAS,which name was the Safety Management Rules for Ship Operations.It clearly stated in the resolution of the General Assembly that 80%of Maritime traffic accidents which occurred on the sea are caused by the driver's subjective judgment of mistakes and the wrong collision avoidance decision.This shows that it is incomplete to finish the collision avoidance relying on the driver's judgment during the voyage of the ship.Therefore,domestic and foreign experts and scholars have already studied the issue of ship collision avoidance.When studying the ship collision avoidance decision,the collision risk plays a certain guidance role of providing some basic theory.Therefore,it is necessary to make a reasonable and correct calculation of the collision risk,so as to comprehensively analyze the possibility of collision with other ships,reduce the subjective influence of the ship operators,and then provide a clear and intuitive judgment for the subsequent collision avoidance decision.Eventually,it can achieve better results of collision avoidance and reduce the possibility of ship collision.This paper proposes a study of the ship collision risk model based on dynamic environment by studying the relevant literatures in many fields of collision avoidance.Based on the influencing factors of collision risk,the effects of CPA,TCPA,the internal between vessels,ship course,ship's speed,wind,flow,visibility,ship density and so on which have an influence on the collision risk are analyzed.the paper integrates the dynamic environmental information and proposes a collision risk model The author studies the wind,flow,visibility and ship density as environmental risks,and classify the risk level for each ship by using the ship's wind resistance grade and use the wind speed as the inflection point of definite weighted functions;The influence of flow and the heading angle of the ship on the environmental pressure value is emphasized.Combining with the experimental results of the Japanese scholar Inoue Shinzo,the method of calculating the environmental pressure value of the flow factor is given,and the definite weighted functions of the water flow is constructed according to the environmental pressure value.The paper summarizes the previous research on visibility,and analyzes that as the visibility distance decreases,the degree of danger gradually increases and becomes nonlinear.Combined with the environmental pressure value and the ship operator's tolerance table,the approximate visibility distance is given;the density of the ship under the situation is divided,so as to obtain definite weighted functions of the ship density;The grey clustering method is used to comprehensively evaluate the navigational environmental risk of each ship.The weight of factor is given by sorting out predecessors'methods of calculating weights so that the risk degree of each factor can be calculated separately.Finally,the method of weighting and comparing the size is used to determine the environmental hazards of ship navigation.The method of determining the weight,giving the weight of each environmental factor,so as to calculate the degree of danger of each factor separately,and finally to empower and comparison of the ways to determine the navigation environment risk.Using the evaluation result,the collision risk is calculated in combination with the ship's motion parameters.The improved fuzzy optimization model is used to achieve the purpose of obtaining the collision risk of all ships in the current encounter situation by one matrix calculation.The author uses the idea of information entropy to judge the dispersion and choose the correct formula for calculating the superiority;the weight of each factor is determined by the combination of subjective and objective methods;Considering the collision risk as a guide of collision avoidance,This paper presents a method to determine the threshold which needs to be taken action.This study uses the improved fuzzy optimization model to calculate the collision risk by analyzing the dynamic information in order to describe the collision risk and results are basis of ship collision avoidance.