【作者】 张金奋；

【导师】 严新平；

【作者基本信息】 武汉理工大学 ， 智能交通工程， 2013， 博士

【摘要】 水路运输在国际贸易中发挥着重要的作用,而保障船舶在航行和运营过程中的安全是一个重要的前提条件。船舶碰撞、搁浅等事故往往会造成严重的经济损失、人身伤亡和环境污染。因此,水上交通风险评价问题受到了人们的广泛关注。针对海湾、海峡、港口航道、繁忙水域等的通航风险评价进行了大量的研究工作。在水上交通风险评价中,很多情况下由于数据量有限等原因,需要利用专家的主观经验知识作为补充,而如何将主观知识和客观数据有效融合是研究的焦点问题之一。此外,船舶碰撞是水上交通事故中最为常见的类型之一,船舶碰撞风险评价和智能避碰决策问题也是水上交通运输领域的重要课题。本文主要针对以上问题开展研究,主要的研究工作和研究成果如下：(1)针对传统置信规则推理方法中没有对不同专家的主观判断进行区别对待的缺陷,提出一种泛化的置信规则库方法(generalized belief rule base, G-BRB),该方法考虑不同专家主观知识的差异,并可以将专家的主观判断和历史数据进行融合,得到最终的评价结果。该方法被进一步应用到碰撞风险评价,将相关的指标划分为安全形势和应急成本投入两个部分,其中安全形势将事故／险情数量、遇险人数和死亡／失踪人数作为评价指标,应急成本投入部分则用海事部门搜救次数和社会力量救助次数两个因素作为评价指标,分别利用G-BRB方法进行推导,最后将安全形势和成本的评价结果进一步融合,得到最终结果。与传统的BRB方法和贝叶斯网络得到的结果比较,并进一步进行敏感性分析,结果显示,提出的泛化的置信规则库方法具有更高的精度和可靠性。(2)提出一种当船舶存在碰撞风险时的避碰决策效果定量评价模型(时空评价模型),分别从时间和空间两个维度对避碰决策效果进行评价,然后利用证据理论对结果进行融合,在时间序列内以两船之间的距离和最近会遇距离(distance to closest point of approach, DCPA)两个参数的加权平均值作为空间增益的量测,以最近会遇时间(time to closest point of approach, TCPA)作为时间增益的量测,并利用D-S证据理论对时间和空间增益进行融合处理,得到每个时刻的决策效果评价结果,最后通过改变相关赋值曲线,分析模型的敏感度和可靠性。(3)在国际海上避碰规则的基本要求下,研究了两条船舶在近距离会遇情况下的避碰时机选择问题,研究中考虑了所有存在碰撞风险的会遇情况,分别对在存在碰撞风险条件下,仅靠让路船采取措施,以及在紧迫局面下,两条船舶同时避让所需要的最小距离进行确定。然后将计算结果与常用的参数,如DCPA、TCPA进行比较,结果表明仅靠DCPA和TCPA来评估碰撞风险很可能会低估避碰难度,而提出的模型得到的结果可以作为一个重要补充。最后,利用三个典型船舶会遇情况进行案例研究,结果表明,两条船舶在采取正确的避让行动条件下,可以在规定的距离内成功避免碰撞。(4)针对多船会遇局面下的避碰决策问题,提出一种分布式实时避碰决策方法,该方法在海上避碰规则的要求下,将所有其它船舶看作是“目标船”,从“本船”的角度研究避碰问题,分别对“本船”为让路船、“本船”为直航船,且“目标船”没有采取避让措施等情况下的避碰决策进行设计,根据会遇情况考虑采取转向和变速两种方式进行避让。对所有船舶都遵守海上避碰规则,以及存在船舶违反避碰规则的多船会遇局面进行仿真,得到以下基本结论：①通常情况下,船舶在避让过程中只采用一次转向或变速操纵,而且一般不会出现船舶同时转向和变速的情况;②采用分布式避碰决策可能会造成不同船舶的操作发生冲突,船舶之间的通信和协调在避让过程中发挥着重要的作用;③根据避碰规则的要求,除非是在极端的条件下,船舶应该尽可能避免向左转向。更多还原

【Abstract】 Maritime transportation plays a significant role in international trade system. The safety of ships during navigation and operation is one of the most important preconditions. Many types of accident like ship collisions and groundings often result in great economic loss, fatalities and the environmental contamination. Consequently, maritime risk assessment is one of the most important focus areas for waterway transportation. A lot of attentions have been paid to the risky areas where traffic density is high for a long time. The areas include gulfs, straits, ports, busy waterways and so on. In a lot of maritime risk assessment, the subjective opinions from experts in relevant domains can be an effective complement in the scarcity of historic data. How to make assessment by combining historic data with expert opinions has been one of the most concerns for researchers. What’s.more, as one of the most common types of accident, collision risk assessment and intelligent anti-collision decision-making are also important topics in maritime transportation. The research of this thesis mainly focuses on the above topics, and the results are as follows:(1) A novel method called Generalized Belief Rule Base (G-BRB) was proposed by making differential treatment for subjective knowledge from different experts, which the traditional method treats them equally. G-BRB can get the final result by combining expert opinions with historical data. The proposed method was further used into collision risk assessment. The indicators were first divided into two parts, namely safety situation and emerging resource cost. Safety was evaluated by accident/incident, distress and death/missing toll while emerging resourcecost was evaluated by salvage and other vessels’assistance. The proposed G-BRB was used to make inference to get the final result. The proposed method was then compared with traditional BRB and Bayes Belief Network (BBN) as well as sensitivity analysis. The results show that the proposed method has higher precision and reliability.(2) A quantitative anti-collision decision making evaluation model called spatial-temporal forensic in collision situation was proposed. The model makes evaluation both in the dimension of space and time. The spatial gain was measured by the distance and DCPA between two ships and the temporal gain was measured by the TCPA between two ships. The D-S theory was then used to combine spatial and temporal gain to get the final evaluation at each time point. Furthermore, the sensitivity and reliability analysis were carried out by changing relevant curves used in the model.(3) Ship anti-collision under the COLREGs based on the maneuverability model was discussed and further studied. The study took all encounter situations into account and obtained the minimum distance required for two encountering ships to maintain clearance of each other under normal situations and critical situations respectively. The results obtained in this paper are also used to compare the proposed model with the traditional anti-collision parameters such as the TCPA and the DCPA. The results show that assessing the collision risk by only the TCPA and the DCPA is quite likely to mislead navigators to take action too late to avoid collision. Therefore, the minimum distances required under both normal situations and critical situations obtained in this paper are necessary for navigators to make wise decisions. At last, three typical encounter situations were used to do case studies. The results show that the two ships can avoid collision successfully within required distance by taking right actions(4) Multi-ship anti-collision problem is studied in a distributed and real time way in this paper. The decision making procedure is carried in a distribute way under the requirements of COLREGs and all the involved ships make decision by their own judgments by treating itself as "Own Ship (OS)" and all the other ships as "Target Ships (TSs)". Both course and speed changing are considered according to the encounter situations. In the model, not only the situation that all the involved ships are complied with requirements from COLREGs is considered, but also the decision making for stand-on ship given that the give-way ship violates the rules is studied. The simulation results show that the proposed procedure can avoided successfully even when some ships did not undertake their responsibilities. The study also draws the following conclusions:(i) Most of the anti-collision operations are carried out by single operation, even in multi-ship encounter situations. What’s more, it is not possible that a ship changes course and speed simultaneously,(ii) Some conflicts between ships’ operations may happen sometimes when they make decisions in a distributive mode. Real-time communication and cooperation among them is very important for collision avoidance,(iii) Turning port side is not advisable for ships to avoid collision according to COLREGs, unless in extreme situations.更多还原