Session Overview Underwater Robotics

It is an auspicious time for this first-ever ISRR special session on the topic of underwater robotics. Underwater robots are now performing high-resolution acoustic, optical, and physical oceanographic surveys in the deep ocean that previously were considered impractical or infeasible. For example: in 2001 the Argo II underwater robotic vehicle, [1], was employed to discover the first off-axis hydrothermal vent field located 15 km from the Mid-Atlantic Ridge at 30 • North Latitude [5]. The dynamics of this important hydrothermal vent site have since been mapped, sampled, and probed extensively with human-occupied submersibles, tethered remotely controlled underwater robots, and untethered autonomous underwater robots [6, 4, 7]. The technical obstacles arising in underwater robotic missions differ from those in land, air, and space missions in several fundamental respects: First, the rapid attenuation of acoustic and electromagnetic radiation in seawater severely restricts the range (and field of view) of high resolution acoustic and optical sensors. In consequence, high-resolution underwater survey sensors must be submerged to the immediate vicinity of a survey site — in sharp contrast to airborne and space-based survey sensors systems. Moreover, radio navigation techniques commonly employed in land, air, and space operations do not function undersea. Second, the high ambient pressure of the underwater environment poses formidable design challenges both for (inhabited) submarines and (uninhabited) robots. At present, only a handful of the world's submarines are capable of diving beyond 1000 meters in depth. Only one present-day operational research submarines can dive to 6500 meters; none can dive to the ocean's deepest depths of 11,000 meters. In contrast, numerous underwater robots operate to 6500 meters, and at least one vehicle presently under construction will be capable of 11,000 meters operation [2, 3]. Finally, in the case of untethered vehicles, underwater missions are limited not only by on-board energy storage capacity, but also by the severely limited bandwidth and delay inherent in underwater acoustic communication, the intelligence of on board control system, and payload capacity.