回歸原航線船舶自動避碰系統之實驗研究

Abstract

本研究之目的在於建置回歸原航線船舶自動避碰系統並透過實驗進行驗證，本研究由三個子系統所組成，分別為偵測系統、避碰決策系統以及控制系統。偵測系統由全球衛星定位系統搭配各儀器設備量測本船與他船的動態資訊，並將動態資訊傳送至避碰決策系統。避碰決策系統透過船舶領域以及碰撞風險指數兩者理論來判斷在符合國際海上避碰規則公約之前提下是否存在碰撞危機，一旦進入到緊急危險階段則將動態資訊傳送至控制系統計算所需操舵舵角。控制系統分為定航向控制系統與變航向控制系統，定航向控制系統使用模糊邏輯控制器以維持航向航行；變航向控制系統則透過迴旋圈試驗求得操縱性指數，藉由Nomoto一階線性近似式可計算出每一時刻的航向角速率所需之操舵舵角，並採用視線導航法航行至新避碰點以遠離來向船，待碰撞危機解除後再回到原航線航行。 根據實驗結果顯示，迎艏正遇避碰情況之兩船最近點距離為15.87m大於本船模之船舶領域範圍，表示本船可安全通過；而在回歸原航線上期間航向角在0.2°及-3.2°之間，平均航向角為1.2°；舵角在0.5°及-2.4°之間，平均舵角為0.9°；而航行過程最大位移量為1.8m，平均位移量為1.32m(約2.3倍船寬)，表示航向角與舵角皆無發散現象，實現回到原航線上航行之可行性。

The ship autonomous collision avoidance system for returning to original route was built and validated by experiments in this study. The autonomous collision avoidance system is composed of three subsystems, which are detection system, collision avoidance decision-making system(CADMS) and control system. The detection system uses the global satellite positioning system in conjunction with various instrument devices to measure the dynamic information of the self-ship and the target ship, and transmits the dynamic information to the CADMS. The CADMS uses the theories of navigation safety domain and collision risk index to determine whether there is a collision risk while complying with the International Regulations for Preventing Collisions at Sea. Once entering the Immediate Danger Stage, the system transmits the dynamic information to the control system to calculate the required steering angle. The control system has two control logics which are fixed heading and variable heading. The fixed heading control system uses the fuzzy control to maintain the heading of the self-ship. On the other hand, the variable heading control system adopts the first-order Nomoto equation of motion model with the coefficients calculated from the ship model turning cycle test. The rudder angle which makes the ship to reach the yaw rate was then determined by the CADMS. Then, uses Line-Of-Sight, the self-ship is guided to sail towards a new collision avoidance point to sail away from the target ship. Once the immediate danger stage is resolved, the self-ship returns to the original route and continues sailing. According to the experimental results, the distance at closest point of approach was about 15.87 meters, which is greater than the navigation safety domain range of the self-ship. This indicates that the self-ship can safely avoid the danger of collision. During the return to the original route, the course angle ranged between 0.2° and -3.2°, with an average course angle of 1.2°. The rudder angle ranged between 0.5° and -2.4°, with an average rudder angle of 0.9°. The maximum displacement during the sailing was 1.8 meters, with an average displacement of 1.32 meters (about 2.3 ship model breadth). This indicates that there were no divergence phenomena in the course angle and rudder angle, demonstrating the feasibility of returning to the original route.