Pattern recognition for underwater docking of unmanned underwater vehicle (UUV)

For underwater control and localization of an unmanned underwater vehicle (UUV), we have used vision information of a suggested pattern image. The pattern is based on suggested criteria. From the pattern specialized on direction information we extracted directional lines and had done Double Hough Transform (DHT) method on them. Once Hough Transform (HT) is usually done for extracting lines from an image. Because our suggested pattern includes lines with a specific order, HT image would show a hidden line relative to the specific order. Hence, DHT could give us the specific order. In our experiment, the specific order is the direction of a docking station for the UUV. In the real experiments, DHT method gave us positional information of an UUV such as leaning direction as well as closeness to a docking station.