Application of scanning sonar using multi - legged underwater robot´s degree of freedom

Generally scanning sonar can be used with ROV or other equipments. When scanning sonar is operated independently of a ROV, it is most often deployed in a stationary tripod, cage or frame, or pole-mounted to survey the seafloor, port wall, and scour at bottom of the bridge. It could offer high accuracy of image position, in comparison with side scan sonar. However, In high current and shallow water, it was too hard to acquire precise images with these kinds of fixture including gimble so far. When scanning sonar is operated with a universal ROV, it is difficult to survey in strong current water. A scanning sonar attached CR200 can be operated in strong current water because CR200 is designed to overcome this. One of its most advantage is possibility of the variable application with scanning sonar and ultra sound camera because of ability to keep stable posture during the surveying and offer degree of freedom. We had conducted the performance test of CR200 at Mado, West Sea of Korea where the excavation of the sunken historical objects is in progress last from 16th April to 15th May. To do this we arranged arbitrary targets around the place, searched and collected them. This paper deals with method of acquiring high quality image from scanning sonar operated with CR200 making full use of degree of freedom and application to navigation with the images in high current and shallow water. CR200 performed successfully the mission to search, identify and collect the imitation relic samples with scanning sonar operation method to figure out to navigation position and to minimize the noise of the conventional sonar image applied to CR200 throughout the experiment.