June 18, 2008 Research into autonomous Underwater Systems by scientists at the University of Washington has resulted in a sub-surface robot that uses fins instead of propellers, and is able to wirelessly communicate enough information to move in tandem with other units. The Robofish is roughly the size of a 10-pound salmon and is designed to track animals and map the bottom of the ocean.
While unmanned vessels are perfect for scouting and studying underwater environments, their autonomy is hampered by communications. Many robots need to resurface in order to send and receive necessary information. To allow the units to operate with minimal interference, the designers took inspiration from the behavior of fish. They found that for group movement to be effective, it is only necessary for a third of the school to know where they’re going. The rest are simply able to fall in with the others. By replicating this behavior in robots, scientists are able to decrease the reliance on seamless communication.
Assistant professor of aeronautics and astronautics Kristi Morgansen has spent five years developing three Robofish that communicate with one another underwater using low power, low frequency sonar, which delivers a bandwidth of 80 bytes per second. Each vessel contains an acoustic transceiver, an RC receiver, and a microprocessor to collect sensor data, handle communication with other vehicles, and determine control commands to the servos. Test results showed that even though only half the information sent between Robofish was received successfully due to the difficulties posed by underwater communications, but because they were programmed to swim as a group the robots could still accomplish their mission.
The Robofish have recently completed a successful test at the International Federation of Automatic Control, demonstrating the foundation for coordinated group movement. The next test will be to trail a remote-controlled toy shark and ultimately, the aim is for the robots to be able to undertake tasks like tracking groups of whales and plumes of pollution or exploring inaccessible undersea cave systems.
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