Navigation system using seafloor geodetic mirror transponders and full-swath mapping system with synthetic aperture and triangle-arrayed interferometry techniques for autonomous underwater vehicle

We started a new three-year project in 2008 for developing a navigation technology accurate to cm-level and a seafloor bathymetric survey technology at cm-level resolution, when AUV skims several tens meters above the seafloor. The technologies could be expected a practical application of searching for submarine minerals, such as thermal vents a few meters high, to a depth of 3,000 meters. We have developed initial L-array interferometric bathymetry sonar and used it in tens of surveys for searching thermal vents on the seafloor so far. The new full-swath sonar project integrating synthetic aperture, triangle-array interferometry, and multi-beam techniques was adequately accepted in recognition of past performances of the present interferometric sonar and high accurate seafloor geodetic survey technologies to centimeters, which have been developed by us and practically used during the past ten years. For the synthetic aperture interferometric bathymetry measurement system, we developed the automatic focusing method and verified its effectiveness to realize a relative position correction on the order of millimeters. We also created five rows of new experimental 1.2 m-long receiving arrays with eight embedded hydrophones, and located them in a triangular position. We will use this triangle array and combine the interferometric system and synthetic aperture processing. Next, we designed and developed the long base line (LBL) navigation system using seafloor acoustic reference stations to realize simultaneous measurement of the distance to the four stations. In the initial year, we developed prototype equipment and designed and investigated the measurement systems using it to achieve our final goal. This year, we are designing and producing experimental systems for practical use based on those test results. Next year, we will conduct actual tests to verify the effectiveness of a submarine resource survey using ROV or AUV. These instructions give you basic guidelines for preparing papers for conference proceedings.