自航船模航向與航跡控制實驗之比較

Abstract

本研究目的為在有風流條件下比較自航船模航向保持控制與航跡保持控制之差異性。航向保持控制使用模糊控制器，航跡保持控制由模糊控制器以及平行修正導航法組成。航向保持控制實驗方式為本船初始位置為於航線上並透過電子羅盤獲得本船之航向來進行航行；航跡保持控制實驗方式為本船初始位置位於航線左側1.8公尺，並設定平行修正導航法平行四邊形之高分別為5、10、15、20、25、30倍船長進行實驗，再透過全球定位系統計算出每個時刻本船偏離航線之位移並求解出新的參考航向再由模糊控制器計算出所要之舵角，由上述6個倍數船長選出航跡保持控制最佳平行四邊形之高為20倍船長。 由航向保持控制實驗結果顯示，航向角在1度及-3度之間擺動，平均航向角為0.975度；而最大位移5.163公尺(約9.2倍船寬)，平均位移量1.610公尺；舵角在6度與-2度之間，平均舵角為1.876度。由航跡保持控制實驗結果顯示，平行四邊形之高為20倍船長時，本船能航行到航線上並且以穩定的船速在航線上行駛，且到達航線後航向角在-4度及4度之間擺動，平均航向角為2.007度；而最大位移0.727公尺(約1.3倍船寬)，平均位移量0.319公尺；舵角在6度與-7度之間，平均舵角為2.776度。由航向及航跡保持控制兩個比較結果可知，航向保持控制會因為風流之影響無法在航線上航行；相反地，航跡保持控制可在有風流時抵達航線並穩定行性，航跡保持控平均位移比航向保持控制小，但平均航向角與舵角皆較大。

The purpose of this study is to compare the difference between the course-keeping control and the track-keeping control of a free running model ship under the condition of wind and current. The course-keeping control is based on fuzzy control and the track-keeping control consists of fuzzy control and parallelogram correction. The scenario of the course-keeping control experiments is to make the model ship placing at the route and sailing along the course by compass. The scenario of the track-keeping control experiments is to make the model ship located at 1.8m to the left of the route and setting the height of parallelogram to be 5、10、15、20、25、and 30 times the ship length. Then, the displacement of the ship model and new reference course is determined by the Global Position System. Finally, the desired rudder angle is calculated by the fuzzy controller. The optimal parallelogram height for track-keeping control is 20 times the length of the ship model from the test results. The course-keeping control experiments results show that the variation of the course angle of the model ship is between 1° and -3°and the average course angle is 0.975°. The maximum displacement is 5.163 meters (about 9.2 times ship model breadth) and the average displacement is 1.610 meters. The variation of the rudder angle is between 6° and -2° and the average rudder angle is 1.876°. The track-keeping control experiment results show that the model ship can sail on the route. When the model ship arrives in the route, the variation of the course angle of the model ship maintains balance between 4° and -4° and the average course angle is 2.007°. The maximum displacement is 0.727 meters (about 1.3 ship model breadth) and the average displacement is 0.319 meters. The variation of the rudder angle is between 6° and-7° and the average rudder angle is 2.776°. From the test results of the course-keeping and the track-keeping control, we can see that the course-keeping control can’t navigate on the route due to the influence of wind and current. However, the track-keeping control can arrive in the route and navigate stably along the route under wind and current. The average displacement of track-keeping control is smaller than that of the course-keeping control, but the average course angle and rudder angle are both larger than that of the course-keeping control.