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‘Robofish’ probes waterways, tracks pollution

After years of development, Michigan State University scientists recently field-tested what could be the ultimate underwater, data-gathering tool: a robotic fish.

According to Xiaobo Tan, associate professor of electrical and computer engineering and designer of the fish, the efficiency of real fish was well worth mimicking in a water-monitoring device. “Fish can perform very efficient locomotion and maneuvering in the water.”

The challenge for Tan and his team was to design a robotic fish that could take advantage of that naturally efficient movement – swimming and gliding – so the robofish could travel autonomously for long distances.

“Swimming requires constant flapping of the tail,” Tan says, “which means the battery is constantly being discharged and typically wouldn’t last more than a few hours.”

The disadvantage to gliding, he says, is that it is slower and less maneuverable.

“This is why we integrated both swimming and gliding in our robot,” Tan says. “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.”

The robot’s ability to glide is achieved through a newly installed pump that pushes water in and out of the fish, depending on if the scientists want the robot to ascend or descend. Also, the robot’s battery pack sits on a kind of rail that moves backward and forward, in sync with the pumping action, to allow the robot to glide through water on a desired path.

Equipped with the latest sensors to transmit water temperature, water quality, and other key measures of the environment to land-bound researchers, the robotic fish – named Grace (“Gliding Robot ACE”) –has already been used on the Kalamazoo River, site of a 2010 oil spill. Watch the video here.

“She swam at three sites along the river and wirelessly sent back sensor readings,” Tan says. “I’m not sure, but we may have set a world record – demonstrating robotic fish-based sampling with commercial water-quality sensors in a real-world environment.”

Underwater gliders, or seagliders, are becoming more common in oceanography. In fact, one traveled all the way across the Atlantic Ocean in late 2009.

One major difference in Grace is that, aside from its swimming capability, it is about 10 times smaller and lighter than a commercial underwater glider.

Tan’s research is supported by the National Science Foundation. For more information about available licensing opportunities, contact Ray DeVito at MSU Technologies (devitora@msu.edu or 517-884-1658). For inquiries about investment opportunities, contact Brian Abraham at Spartan Innovations (babraham@spartaninnovations.org or 517-884-4543).