Study on Development of the Automatic Navigation System for Ships

为了防止海上事故的发生，对航行安全提出了很高的要求。然而，最近为了降低总运输成本，不得不减少人力费用，这意味着很难确保技术优秀的水手。因此，未来由于船员技术水平下降而引起的海难事故的增加令人担忧，自动导航装置的引入是解决这一问题的途径之一。本研究假设利用差分全球定位系统（DGPS）得到的位置信息，研究了利用模糊推理来评估碰撞风险并确定对策以避免与其他船舶碰撞的自动导航系统，该系统存在于本船周边的障碍物。在数值模拟的基础上对系统进行了设计，并通过数值模拟结果与模型试验结果的对比验证了系统的有效性。模型试验结果表明，该系统能很好地控制船舶改变航向或避免与航道上障碍物的碰撞。仿真结果与模型试验结果比较吻合较好，表明该仿真模型对船舶运动具有较高的估计精度。为验证系统的有效性，对多个船舶在碰撞危险情况下的几种相遇情况进行了数值模拟。结果表明，该算法对仿真研究中使用的场景效果良好。因此，采用模糊推理的自动导航系统将有助于船舶的安全航行。

Navigational safety is highly demanded in order to prevent marine accidents. However reduction of personnel expenses is enforced recently to reduce total transportation cost and it means that securement of the sailors who have an excellent skill becomes difficult. So increase of sea disaster accident originated with degradation of skill of a sailor is concerned in the future and introduction of an automatic navigation device is one of solution of such a problem.In this study, supposing to utilize positional information which is derived using DGPS (Differential Global Positioning System), research on development of automatic navigation system which utilize fuzzy inference to evaluate the risk of collision and to define countermeasures to avoid collision with other ships obstacles which exists in circumference of own ship was carried out.The systems were designed based on a numerical simulations and verification of effectiveness of the systems was done by comparing results obtained by numerical simulation and by model test. The model test results shows that the system can control ship well to change her course or to avoid collision with obstacles on course. Comparison between simulation results and model tests results agree well, then our simulation model has high accuracy to estimate ship motion.Numerical simulations assuming several encounter situations of plural ships in collision risk were made to confirm validity of the system. It was observed that the algorithm works well for the scenarios utilized in the simulation study. Then the automatic navigation system using fuzzy inference may be useful to navigate ship safely.