Development of Integrated Acoustic Communication and Positioning System for Operation of Autonomous Underwater Vehicles and a Sea Trial

Abstract

Abstract An integrated acoustic communication and positioning system for the operation of autonomous underwater vehicles (AUVs) was developed, in which the acoustic communication function and positioning functions are integrated and the transmission timing of acoustic packets is controlled to efficiently use time and frequency resources. A chip scall atomic clock (CSAC) is equipped with the system and the systems on each vehicle are synchronized. The propagation time of the acoustic packet is then measured with one-way time (OWT) of flight and information of transmission time. In the integrated and synchronized mode, uplinks (ULs) from AUVs are periodically transmitted, and transmission timing of downlinks (DLs) from autonomous surface vehicle (ASV) is controlled to avoid collision of the ULs and DLs. A sea trial was conducted in a deep-sea area with a water depth of 1,100–1,150 meters. Four AUVs were simultaneously operated with an ASV for positioning and monitoring the AUVs using the developed acoustic system with the integrated and synchronized mode. The AUVs cruised for 2.5 hours near the seabed. The developed system worked well and the sea trial was successfully performed. The period of hull swing of the ASV was rapid owing to its small body and the Doppler effect was varied quickly; however, the acoustic communication was stable. Positioning and control of transmission timing was successfully achieved. On the other hand, an improvement in the accuracy of positioning is desired for operation in deep water areas.