Underwater navigation and hydrophone networks
MIT Lincoln Laboratory is developing hardware and algorithms for underwater navigation and perception to help divers and autonomous underwater vehicles collaborate, and SEA will supply hydrophones for an autonomous undersea monitoring network. Both announcements appeared this week and extend sensing focus below the sea surface. ( )
Underwater robots are getting new ways to find their place and listen below the surface, where Global Positioning System signals fade and cameras often fail. (news.mit.edu) (dosits.org) MIT Lincoln Laboratory said on April 14 that its researchers are building hardware and algorithms to help divers work with autonomous underwater vehicles on missions such as cable repair, search and rescue, harbor entry, and countermine work. The lab said the effort is part of its Advanced Undersea Systems and Technology Group. (news.mit.edu) (ll.mit.edu) SEA said on April 9 that it will supply hydrophones to OSHEN for a ZeroUSV-led project backed by United Kingdom Defence Innovation and the Defence Science and Technology Laboratory. The system will use sail-powered C-STARS micro-drones launched from the Oceanus12 uncrewed surface vessel to form a distributed acoustic network. (sea.co.uk) (ukdefencejournal.org.uk) A hydrophone is an underwater microphone: it turns pressure changes in water into electrical signals that can be recorded and analyzed. Arrays of hydrophones can hear more sensitively than one sensor alone and help estimate where a sound came from. (oceanservice.noaa.gov) Underwater navigation is hard because the radio frequencies used by Global Positioning System satellites do not penetrate seawater. That is why underwater systems often fall back on acoustics, using timed sound signals between vehicles, seafloor stations, or surface buoys to estimate position. (dosits.org) MIT’s project starts from that constraint. Principal investigator Madeline Miller said divers often rely on a compass and fin-kick counts, while robots can process data, move faster, and stay underwater longer, so the lab is trying to combine the diver’s dexterity with the vehicle’s computing and endurance. (news.mit.edu) (ll.mit.edu) The lab said one prototype pairs a diver carrying a “tube-let,” a tube-shaped tablet with position and velocity sensors, with an autonomous underwater vehicle carrying a custom optical-acoustic payload. The goal is to let the machine map or inspect first and guide the human to the exact spot where hands-on work is needed. (news.mit.edu) (ll.mit.edu) Perception is the second problem. MIT said cameras lose usefulness in darkness and turbidity, while sonar images show shapes and shadows rather than color, and the shortage of large labeled sonar datasets has slowed training for underwater artificial intelligence systems. (csail.mit.edu) (news.mit.edu) The SEA project is aimed less at guiding a single diver than at persistent listening across a wider area. SEA and OSHEN said the network is designed to monitor communication signals from underwater assets using low-power sensors on long-endurance surface craft. (sea.co.uk) (ukdefencejournal.org.uk) Both efforts point to the same shift: more of the ocean is being sensed by teams of machines that navigate with sound, not satellites. The next test is whether those systems can keep working in murky, cluttered water where humans still do the final, precise tasks. (news.mit.edu) (sea.co.uk)
