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A Verification Study and Ship Motion Measurement of an Improved Visual Guidance Scheme by Using a Small Boat-Based Experiments
|Contributors: ||NTOU:Department of Transportation Science|
Image Processing;Leading Line Guidance;Improved Leading Marks Guidance;Virtual Leading Line;Autopilot
|Issue Date: ||2013-10-07T02:32:22Z
|Abstract: ||摘要:本案旨在於利用影像處理技術，建立改良式視覺導航法則之小型船舶之實船試驗，並應用於船舶自動導引入港系統。由於一般船舶進港時慣用之傳統式疊標導航概念，其疊標設計為前後擺設，該設計僅能提供特定的導航參考位置及航向，除了進港導引之外無法提供額外服務。本研究將驗證改良式視覺導航概念，將傳統式之疊標由前後擺設方式，改良為左右擺設之導航標誌，如此可沿著碼頭岸壁形成一基線，當利用影像處理加上設定比例方式，即可產生垂直於此基線上之任意虛擬導航線，利用此虛擬之導航線可零活用於船舶導引進港及靠泊目標之導引參考，使用上較傳統疊標導引方式更具彈性。其中影像資訊以CCD攝影機擷取之，利用影像處理分析技術之顏色辨別方式來判斷導航標誌之所在，藉由計算導標之幾何中心位置，再利用影像座標關係，作為本船與導航標誌間之相對導航修正量之計算基礎。經由自航控制器做一序列航向變換控制，將船舶導引、控制至預定航道線上。本計畫擬於小型船舶實驗時一併量測船舶之運動姿態，藉以探討控制器對船舶運動之影響情況。 藉由本計畫之進行，將可具體了解改良式疊標導航法之實用性以及自航控制器對船舶運動之影響及優缺點。本研究先將利用電腦計算模擬方式尋求較佳之控制參數，並與傳統式疊標導航法相比較，先行完成視覺導航之船位自動導航控制系統之開發研究，再利用小型FRP船，於海洋大學小艇碼頭水域進行小型船之實船驗證測試。並比較其軌跡收斂特性及控制結果，將可具體評估改良式疊標導航法與傳統式疊標導航法之應用差異性，並進行控制器性能對船舶運動量測之探討。|
Abstract:This proposal is a verification study of an improved visual guidance scheme while using a small FRP boat as the test platform for the approaching maneuver. The traditional leading marks are designed in tandem to form as a leading line that defines the reference track to be followed during the vessel approaching phase. This leading line concept only serves for a fixed purpose and the performance degrades if the depth between the leading marks is limited. In the proposed approach, two canvas targets are arranged along the berth to serve as leading marks that define a base-line. These leading marks are captured by a CCD camera, and the resulting image is processed using a color recognition scheme and noise filtering scheme to accurately detect the location of the two targets in the image. The geometric centers of the two leading marks are then calculated, and the separation distance between them is used to compute the deviated heading angle. An appropriate ratio setting between the two targets on the base-line allows us to define so called virtual leading line that is perpendicular to the base line defined by joining the two leading marks. A variable leading line concept can be achieved with different setting ratio between two marks. Guidance situations are considered, namely, trajectory tracking when the reference leading line for the vehicle is given beforehand. A trigonometric relation is used along with the target image information in estimating the angle between the boat and the leading marks. The deviated heading angle is then supplied to an autopilot control system as an error signal and is used to generate the rudder commands required to steer the boat toward the virtual leading line. This project also intends to measure the ship motion behavior during the automatic visual guiding the vessel to the berthing standby region. These measurements result will be a useful data for the autopilot performance analysis. This proposal is concerned with the comparison of two types of visual guidance methods; namely, the traditional leading line concept and improved leading line method (variable leading line concept). The feasibility of the proposed approach is verified by performing a series of small boat based experiments. In the first stage, the computer simulations are conducted to evaluate the feasibility of the visual based virtual leading line guidance method. The next stage, the feasibility of the autopilot system will be verified by performing a series of approaching maneuvers using a small FRP boat in the harbor attached to the National Taiwan Ocean University (NTOU). The trajectories, the rate of convergence of the boat toward the leading line during the approaching maneuver experiments can be evaluated the performance between the traditional leading line concept and the improved leading line method. The ship motion measurements data also can be used as a performance index for the autopilot system design parameter.
|Appears in Collections:||[運輸科學系] 研究計畫|
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