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Evaluating the Water

Similar challenges exist for marine systems. GPS signals, which serve well for aerial vehicles, cannot penetrate underwater. The Marine Technology Program at SRI International, based at the research institute’s St. Petersburg, FL, branch, is working on advanced systems that allow underwater vehicles to precisely navigate without GPS.
SRI is also working on sensors that are smaller, cheaper, and demand less energy. Says Larry Langebrake, director of SRI, “You need a mission controller onboard the vehicle that has enough computing capability that it can take multiple sensory input, such as position and chemical composition, and use those together to make decisions.” That demands increased computer power, he explains, and miniaturized low-power sensors will free up power for use elsewhere in the vehicle. SRI has already employed its AUVs and sensors in fisheries research and has mapped and catalogued a Civil War–era steamship off Florida’s west coast.
John Reed, senior research scientist at the Harbor Branch Institute at Florida Atlantic University, recently spent a week testing two new AUVs to scan the seafloor off the coast of Florida for deep-sea corals. “Over the past decade, we’ve discovered hundreds of deep-sea reefs that nobody knew were there,” he says.
These AUVs do not make their own autonomous decisions about movement; rather, they follow specific directional plans to gather data. “We fly the AUV about 50 meters off the bottom, and the side-scan sonar puts out a wide beam to map an area 1,000 meters wide,” says Reed. “In 24 hours, we mapped about 30 square miles.”

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