INTEGRATED ACOUSTIC COMMUNICATION AND POSITIONING SYSTEM BETWEEN AN AUTONOMOUS SURFACE VEHICLE AND AUTONOMOUS UNDERWATER VEHICLES

In underwater observation using an autonomous underwater vehicle (AUV), a support vessel typically monitors the AUV to support the observation. In order to make the AUV operation more efficient, an autonomous surface vehicle (ASV) and an acoustic multi-access communication and positioning system have developed. The developed acoustic system achieves multi-access with frequency division multiple access (FDMA) method, and the ASV can monitor up to three AUVs simultaneously. Positioning is performed with super short baseline (SSBL) method. The acoustic device has operation mode in which positioning and communication functions are integrated to achieve efficient uplink and accurate downlink simultaneously. Two observation operations were conducted successfully. In one of those, the ASV communicated with two types of AUVs during observation in 1250m water depth, then multiple access were achieved. Even nadir angle for one AUV became almost 40 degrees, the acoustic communication was performed. In another observation, two cruising AUVs were operated with a vessel and the ASV in 1500m water depth. The ASV monitored one AUV. Condition in case the device is equipped on small body of the ASV was evaluated. The communication was performed in this depth in severe condition. Furthermore integrated sequence of positioning and communication was successfully performed. Requirement in next phase, in which operation depth and number of multiple access are increased, is discussed.