Open ocean aquaculture often needs a set of underwater and surface vehicles for its operation. While it interacts with fish and fish pens, the state of the underwater vehicle is poorly known. The surface vehicle, which is tethered with the underwater vehicle, can thus act as a sensor node to collect information on the surface and better-pose the underwater vehicle.
This paper presents a foundational strategy of the team of unmanned underwater and surface vehicles, which cooperatively localizes and navigates the vehicles. For the localization, the surface vehicle identifies its pose with a Global Positioning System (GPS) and a compass. To localize the underwater vehicle, the surface vehicle is equipped with a sonar sensor whereas the underwater vehicle observes the surface vehicle using a camera. Since the underwater vehicle conducts tasks for aquaculture, the surface vehicle understands the intention of the underwater vehicle through the tethered communication and moves along the underwater vehicle.
Experimental work using a team of unmanned underwater and surface vehicles shows that the proposed strategy allows the cooperative operation of the underwater and surface vehicles.