More robotic fish spawned to monitor water quality
By Darren Quick
November 4, 2009
Although fish numbers are in decline in oceans all around the globe, the same can’t be said for their robotic brethren. Like the “Robotuna” from MIT and the robots developed by a team at the University of Essex, the latest robotic fish from Michigan State University (MSU) also take inspiration from nature. The aim is to give researchers more precise data on aquatic conditions and provide a deeper understanding of critical water supplies and habitats... and hopefully help improve the outlook for fish of the biological variety.
Millions of years of evolution has resulted in fish that are perform very efficient locomotion and maneuvering in water. So to probe underwater environments the MSU researchers are developing robots that use advanced materials to swim like a fish. To mimic fish movement the robotic fish will feature fins built with electro-active polymers that use electricity to change shape. Similar to real muscle tissue, ion movements twist and bend the polymer when voltage is applied. The effect works in reverse, too - slender “feelers” could signal maneuvering circuits in a sort of electro-active central nervous system. Infrared sensors also could be used for “eyes” to avoid obstacles.
The robotic fish will carry sensors recording such things as temperature, dissolved oxygen, pollutants and harmful algae. Xiaobo Tan, an assistant professor of electrical and computer engineering, is also developing electronics so the devices can navigate and communicate in their watery environment.
The robots will communicate wirelessly with a docking station after surfacing at programmed intervals and could similarly be linked to other robotic fish for coordinated maneuvers or signal relay. Global positioning system technology and inertial measurement units will allow precise navigation. Robotic fish – perhaps schools of them operating autonomously for months – could give researchers far more precise data on aquatic conditions, deepening our knowledge of critical water supplies and habitats.
A 9-inch prototype now swimming in Tan’s laboratory tank is modeled on the yellow perch by John Thon, a member of the research team who teaches art at nearby Holt Junior High School. The device isn’t strong enough to resist stiff currents, so for now must be confined to relatively still waters. Future versions will incorporate the ability to change buoyancy to assist locomotion and maneuver.
“The robotic fish will be providing a consistent level of data that hasn’t been possible before,” Elena Litchman, an assistant professor of zoology, explained. “With these patrolling fish we will be able to obtain information at an unprecedentedly high spatial and temporal resolution. Such data are essential for researchers to have a more complete picture of what is happening under the surface as climate change and other outside forces disrupt the freshwater ecosystems. It will bring environmental monitoring to a whole new level.”