Acoustic positioning system of combined aerial and underwater drones

The authors have developed a prototype of a combined aerial and underwater drone system, which contributes to safety and solution to labor shortage in aquaculture monitoring work in the fishery industry and inspection work of water infrastructure (piers, etc.) in harbors and rivers. The aerial drone flies automatically to the destination area conveying the underwater drone, and after it alights on the water, the underwater drone starts to cruise. Its mobile network communication realizes automatic flight, remote control, and real-time transmission of video signals of both drones. After the underwater drone completes its mission, it is collected by the aerial drone again and the aerial drone flies back to the base station automatically. Remote control of the underwater drone is realized utilizing its location information, provided by our acoustic positioning system that is indispensable under the sea where GPS cannot be used. This paper describes the details of this acoustic positioning system of our combined aerial and underwater drones. It is based on SSBL, and uses a pinger instead of a transponder to keep costs down. In addition, a relatively short chirp pulse is generated in order to improve resistance to reflection. Future work will include improvement of the accuracy and stability of acoustic positioning in order to realize the automatic cruise of the underwater drone as well as the aerial drone, as the underwater drone is currently operated manually.