Development of underwater 3D positioning system using underwater acoustic modem

This paper presents the development of an underwater positioning system using underwater acoustic signals. The positioning system was developed on the basis of a conventional underwater acoustic modem. Additional hydrophones were installed to the conventional acoustic modem so that three-dimensional underwater positioning became available. A communication transducer was used for the acquisition of range information as well as underwater communication. The four additional hydrophones were used to estimate the three-dimensional angular information. The three-dimensional angular data were acquired by using the time difference of the arrivals of two pairs of acoustic signals. The time delay between two acoustic signals was acquired by using a probabilistic method based on the Bayesian update process. It could provide a reliable and accurate estimation. The acquired range and angular data were used to localize the underwater target equipped with a transmitting acoustic modem. The performance of the developed system was verified by experiments conducted in an inland water environment by using an unmanned surface vehicle. © ICRO OS 2019.