Three major stumbling blocks have so far prevented demonstrating the potential applications of Autonomous Underwater Vehicle (AUVs) to demanding industrial and scientific missions. Namely, i) the lack of reliable navigation systems, ii) the impossibility of transmitting data at high rates between the AUV and a support ship at slant range, and iii) the unavailability of advanced mission control systems that can endow end-users with the ability to plan, program, and run scientific / industrial missions at sea, while having access to ocean data in almost real-time so as to re-direct the AUV mission if required. As a contribution toward solving some of the abovementioned problems, this project puts forward the key concept of an Autonomous Surface Vehicle (ASV) that will operate in close cooperation with an AUV, as a mobile relay for fast communications. In the scenarios considered, the ASV will be equipped with a differential GPS receiver, an ultra short baseline unit (USBL), a radio link, and a high data rate communication link with the AUV that will be optimized for the vertical channel. Thus, by properly maneuvering the ASV to always remain in the vicinity of a vertical line with the AUV, a fast communication link can be established to transmit navigational data from the DGPS and USBL to the AUV, and ocean data from the AUV to the ASV, and subsequently to an end-user located on board a support ship or on shore. Fast and reliable communications, as well as precise navigation, will thus be achieved by resorting to well established technologies.
The main thrust of the project is the enhancement and integration of proven technological systems to achieve coordinated operation of an AUV and ASV, while ensuring the integrity of the two platforms. To give the work greater focus, the final goal of the research and development effort is to perform a mission at sea – near the Azores islands – down to depths of 100 m, to determine the extent of shallow water hydrothermalism and to determine the patterns of community diversity at the vents in the area. In the envisioned scenario, the AUV will be asked to maneuver close to the seabed and to detect the occurrence of bubble emissions from discharging vents. The detection of those phenomena will in turn trigger the acquisition and transmission – to a support unit – of time/space stamped sonar and video images through the vertical acoustic channel, via the ASV.
Obstacle avoidance and bubble detection will rely heavily on the development of a space-stabilized sonar head with vertical and horizontal transducer elements, and the associated signal processing algorithms.
Programming, executing, and modifying on-line the plans for joint ASV/AUV operation will be made possible by developing dedicated systems for joint mission and vehicle control, as well as appropriate Human-Machine interfaces. Special emphasis will be placed on demonstrating all the steps that are necessary to acquire, process, manage, and disseminate data on hydrothermal activity to a wide audience of scientists, over the Internet.