A new species of robot fish has been spotted in the Kalamazoo River in the state of Michigan, where more than a million gallons of oil spilled in July 2010. Developed primarily by Xiaobo Tan, an associate professor at Michigan State University (MSU), the robot's sensors detected crude oil at various sites along the river.

Grace (Gliding Robot ACE) differs significantly from this prototype we covered back in 2009, which was based on the yellow perch. It may look more like a torpedo than the catch of the day, sporting a sub-like hull and a pair of huge wings, but that's intentional. The wings help it to conserve energy by gliding for long periods of time.

“Swimming requires constant flapping of the tail,” Tan said, “which means the battery is constantly being discharged and typically wouldn’t last more than a few hours.” By combining spurts of tail fin propulsion and slow and steady gliding, Grace has a much longer range than other robo-fish – approximately 124 miles (200 km) under good conditions.

Its buoyancy is controlled by a battery-powered pump, which forces water into and out of its body. This is combined with a sliding weight (its battery) inside its fuselage, which changes the robot's center of gravity, causing it to dive or surface on command. By surfacing at regular intervals, it can send a steady stream of sensor readings to researchers over a wireless connection.

“This is why we integrated both locomotion modes – gliding and swimming – in our robot,” Tan said. “Such integration also allows the robot to adapt to different environments, from shallow streams to deep lakes, from calm ponds to rivers, with rapid currents.”

It's one of a handful of projects that could help protect and monitor aquatic environments in the future. You can see it swimming in the Kalamazoo river in the following video.

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