Study on Development of the Automatic Navigation System for Ships

为了防止海上事故的发生，对航行安全的要求很高。然而，最近为了降低总运输成本而强制减少人员费用，这意味着很难确保具有优秀技能的水手。因此，今后由于船员的技能下降而引起的海难事故的增加受到关注，引入自动导航装置是解决这一问题的方法之一。（差分全球定位系统），研究开发自动导航系统，利用模糊推理来评估碰撞风险，并确定避免与其他船舶障碍物碰撞的对策，在数值模拟的基础上进行了系统的设计，并通过数值模拟和模型试验的对比，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开航向障碍物。仿真结果与模型试验结果吻合较好，表明该仿真模型具有较高的运动估计精度。据观察，该算法的效果很好的模拟研究中使用的场景。因此，利用模糊推理的自动导航系统可能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.