多組疊標導航之船舶自動入港航行系統

Use of Multiple Leading Marks Guidance in an Automatic Ship Approaching Maneuver System

本文旨在探討結合影像處理技術，及多組疊標導航概念，應用於船舶沿Z型曲線航道自動入港航行系統設計及實驗。實驗以架設於船艏CCD攝影機來擷取船舶入港航行之參考疊標影像，作為回授系統輸出訊號之量測依據，提供即時導引資訊，最後再結合入港航行控制器及轉向控制器，導引船舶沿著曲線式預定航道來航行，以達到視覺導引自動入港之目標。在影像處理過程中，採用顏色辨別方式，擷取岸上不同顏色疊標辨識物影像，將擷取到之影像進行色彩空間轉換，由RGB色彩空間轉換至HSV色彩空間。並配合數位影像處理技術，找出CCD攝影機擷取畫面中疊標所在位置，進而依疊標影像質心座標位置，計算航向角修正量以及估測距離。自航控制器由兩個部分組成，其一為入港航行模糊控制器，係依不同疊標擺設方式可分為前後疊標以及左右疊標兩種設計。第二部分為轉向模糊控制器，主要由距離資訊來判斷是否需執行轉向動作，係依據本船與疊標間之相對安全距離所對應之舵角需求設計轉向控制器之模糊規則。本論文主要透過入港航行控制配合轉向動作，將船舶由某航向之航路導引至另一不同航向之預定航道上，完成較符合實際入港所需採取之分段式導引操縱需求。最後實船入港試驗則於海洋大學小艇碼頭水域進行，用以確認本論文所提之藉由影辨識來達到船舶自動導引進港之可行性。實驗結果顯示，本研究所提出之系統於地形受限之環境下，透過分段式導引，可成功應用前後擺設、左右擺設之疊標，結合模糊控制自航器，自動將船舶導引至Z型曲線式預定航道上，使其更為符合實際入港航行模式之應用需求。 This work is on the use of image processing technique, fuzzy logic control, and multiple leading marks to a small boatbased automatic guidance and control approaching maneuver along a path defined by multiple leading line segments. A CCD camera mounted on the bow of a small FRP boat is used to acquire images of the leading marks used in defining the multiple leading line segments. Specifically, color recognition scheme is adopted to transform the images from the RGB space to the HSV space, and the coordinates of the center of gravity of the acquired images are identified, which are then employed to compute the heading angle deviation and relative distance needed to steer the boat along the leading line segments. The autopilot system is consisted of an approaching controller and a turning controller. Both the fore-aft and left-right leading mark arrangements are adopted for the fuzzy approaching controller design. The minimal rudder angle requirements associated with different distance for a safe turning is considered for the fuzzy turning controller design. Experiments are conducted on the waterways of the National Taiwan Ocean University (NTOU) small boat harbour and experimental results indicate that the small FRP boat is able to steer automatically along a z-shaped approaching curve defined by three leading line segments, which bear much resemblance to the real world approaching maneuver scenario. This indicates the feasibility and potential use of the proposed system.