| Summary: | 碩士 === 國立臺灣海洋大學 === 通訊與導航工程學系 === 100 === 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.
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