An experiment of real-time data transmission of sonar images from cruising UUV to distant support vessel via USV: Development of underwater real-time communication system (URCS) by parallel cruising

Seafloor investigations with unmanned underwater vehicles (UUVs) have been carried out in various situations. It is expected in future that seafloor investigations of sea area where manned support vessels cannot enter will be accomplished with UUVs. For searches after an accident and a disaster, detected objects should be immediately identified. In such situation, it is convenient to have a system, that transfers UUV status data and/or observation data from an UUV to a distant base in real time. Therefore, we have developed the Underwater Real-time Communication System (URCS) where unmanned surface vehicle (USV) relays UUV status and Sonar images to a distant base in real-time. The USV communicates with the UUV by two sets of acoustic device and with the distant support vessel by satellite communication. For the USV to receive image data from UUV it is necessary to keep USV just above the UUV, because high-speed acoustic device used for image data transmission has strong directivity in general. Therefore, we have developed Parallel Cruising Technology by using Cooperative Control (PaCTeCC) method. A sea trial of real-time data transmission of sonar images from the cruising UUV to the distant support vessel via the USV was conducted in July 2014. In this paper, we report the details of PaCTeCC method and the experiment results.