||Unmanned underwater vehicle with multibeam sonar system formed by the underwater multibeam sonar system. It can get better quality survey data because the system is more closer to seabed and not easily impacted by the sea wave's influence. The patch test procedure is the first stage required in any multibeam echosounder survey. It is designed to precisely determine the static configuration between the sonar head and motion (roll, pitch, yaw). When doing the Patch test, working boats need to have high-precision positioning systems, and good manipulation to accomplish specific measurement mode. Because of the limited by the lack of positioning accuracy and poor manipulation, underwater vehicle is not easily to do the traditionally patch test .|
In this experiment, using search method to change the correction angle of the axis between sonar and motion sensor, and recalculate the nadir beam's depth value, calculated for each axis deviation angle of correction by observing the variation of water depth. In this study, taking two water multibeam bathymetry of the actual cases and comparison the patch test calculated by this experiment with traditional method. In the roll angle correction, the two different way can get very close result, the difference values is -0.4 and -0.23 degrees; In the pitch angle correction, the difference values is -0.55 and 0.57 degrees.
Finally, using this experiment to calculate the correction angle of the axis between sonar and motion sensor of the underwater multibeam sonar system, and recalculate the depth value. Because of the limited by the lack of positioning accuracy the feature on the seabed can’t match very well, but the terrain can match very well. This result prove the method proposed by this experiment can work well in the case of lack of positioning accuracy and poor manipulation situation.