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Visual Guidance and Control of A Small FRP Boat in The Night Time
|Authors: ||Sin-Der Lee|
|Contributors: ||NTOU:Department of Transportation Science|
RoI(Region of Interest);Autopilot;Fuzzy Control;Night Time Guidance
|Issue Date: ||2015-05-19T06:32:04Z
|Abstract: ||摘要:本文主旨在以航海人員慣用之前後疊標視覺導航概念，在夜間環境下使用影像處理技術並配合船舶自航控制器，導引小型FRP船舶自動行駛於進港航道上。為了使船舶能提早駛於航道上，本文提出前後疊標導航法之改良式計算法,並驗證改良法之船舶軌跡收斂改善效果。實驗中增加CCD旋轉機構以提升視角範圍，增加追蹤導航疊標之能力避免目標出鏡，強化抗風、流干擾之能力，以避免導航用之影像資訊中斷導致船舶暫時失控。實驗流程乃以船艏所架設之CCD攝影機擷取岸上影像，透過影像處理程序進行HSV篩選與感興趣區域(RoI, Region of Interest)選取，以濾除背景干擾光源進而擷取正確之導航疊標，並將解算出的疊標質心應用至前後疊標導航法。本文採用兩種不同計算方法解算出航向修正量，並配合模糊與內模式自航控制器，輸出適當舵角命令將船舶自動導引於航道上。本研究歸納出紅色LED光板為夜間環境中較易辨識之目標，LED光板小尺寸之特性亦可減少質心計算偏差量。實驗結果顯示，改良式計算法則解算之角度較大，可在較早的時機將船位修正至航道上，較符合真實操船行為。|
abstract:This work adopts the popular concept of visual guidance scheme practiced by the mariners, namely, the fore-aft leading mark as the guiding aid and uses the image process technique along with autopilot to guide the FRP (Fiber Reinforced Plastic) boat towards a prescribed straight water channel. In order to have the boat steer to the leading line earlier, a modified algorithm of fore-aft leading mark guidance method is proposed and improvement of the ship trajectory convergence rate is verified via experimental studies. Use of a rotating stand; hence, improves the field of view of the CCD camera lessens the oscillating problem caused by sea disturbance . Moreover, it can prevent loss sight of the target to ensure the boat is continuously under visual guidance and control. An image processing unit mounted on the bow of the boat is used in capturing a set of targets placed on the shore. Proper thresholds of HSV (Hue, Saturation, and Value) are set and the RoI (Region of Interest) scheme is adopted during the image processing process to enhance identifibility of the leading mark. Moreover, filtering of the background light source disturbance is considered. The reference heading angles are calculated by two types of fore-aft leading mark guidance methods and fed into the fuzzy logic autopilot and the Internal Model Control (IMC) autopilot to steer the boat towards the leading line. Experimental studies indicate adoption of red LED (Light-emitting Diode) improves target recognition possibility, and the small size nature of the LED also reduces the error range of the computed center of leading mark as compared with color canvas targets. Specifically, the reference heading angle calculated by the proposed modified algorithm of fore-aft leading mark guidance method is larger, thus, reduces the time of convergence to the leading line and better resembles the real maneuvering behavior.
|Relation: ||Vol.31，No.3, pp.155-166|
|Appears in Collections:||[運輸科學系] 期刊論文|
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