In 2016, US antidrug agents intercepted a strange vessel off the California coast: a homemade fiberglass submarine. Inside, the small craft was packed to the brim with 12,800 pounds of cocaine, a cargo worth more than $193 million. Since the early 1990s, at least 60 of these narco-subs have been captured. They’re sophisticated contraptions, with multiple crew members and GPS navigation—and their sole purpose is to sneak massive amounts of cocaine, heroin, and other illegal drugs into the country. They’re exceptionally good at their job.
“There may be hundreds more of these subs out there, but, statistically, only a few of them will be caught,” says Greg McDaniel, a College of Engineering associate professor of mechanical engineering. “They’re very difficult to detect.”
McDaniel is trying to improve those odds. With $355,000 in grant funding from the US Naval Sea Systems Command, he and a team of graduate and undergraduate researchers are developing new seafaring robots that can patrol large areas together and collaboratively hunt for underwater threats.
Right now, he says, US agents’ primary means of detecting narco-subs is through towed sonar arrays, which are essentially long cables covered with underwater microphones and dragged behind a ship. These do a decent job of listening for possible targets, but can be used only in relatively deep water and can detect sound only within a limited range. In some cases, it’s also possible to use sophisticated underwater robots called Bluefins to listen for targets, but even these complex machines have their limitations. While they’re much nimbler than a surface ship, they can detect targets only within a few miles and can’t easily communicate their discoveries to human operators while…