In recent years, there has been increasing interest in the use of Autonomous Underwater Vehicles (AUVs) for the exploration and exploitation of the ocean. However, AUV users are still largely limited to a reduced number of scientific institutions, as most of the existing prototype vehicles have been designed to conduct simple survey missions that do not require close interaction with their operators or the environment. It is by now widely recognized that some unresolved issues stand in the way of demonstrating the vehicles potential applications to demanding industrial and scientific missions. Namely, they lack the capability to operate autonomously yet in closer contact with end users, and the capacity to use on-board acoustic and video sensors for close-range inspection of underwater phenornena or structures.
Four major stumbling blocks have thus far prevented AUV developers from meeting the aforementioned goals: i) the lack of reliable navigation systems that can dispense with the cumbersome deployment and calibration of arrays of transponders, 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 which endow end-users with the ability to plan, program, and run scientific/industrial missions at sea, while having access to ocean data data in almost real-time so as to re-direct the AUV mission, if required.
As a contribution toward solving 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 communication purposes. Both vehicles will be available at the beginning of the project. In particular, the AUV will be equipped with all the hardware and software systems for basic vehicle and mission control. In the scenarios envisioned, 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 direct to the AUV, a fast communication link can be established to transmi 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, can thus be achieved by resorting to conventional systems.
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 research and development will be aimed at performing a realistic mission at sea, near the Azores islands, to determine the extent of shallow water hydrothermalism, and the patterns of community diversity at the vents in the area. In that mission scenario, the AUV will be asked to maneuver close to the seabed to detect the occurrence of bubble emissions from the vents, and trigger the acquisition and transmission to the support unit of time/position 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 Man-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.
Funding SchemeCSC - Cost-sharing contracts
29240 Brest Naval
LA12 7NE Ulverston
9900 Horta - Acores