A researcher at University of Washington has created a wireless network – based on sonar pulses – that allows her swimming robots to communicate with each other underwater.
The three “Robofish” are programmable, finned robots that swim underwater by mimicking the motions of real fish. At a recent workshop on guidance and control of underwater vehicles, their creator, assistant professor of aeronautics and astronautics Kristi Morgansen, demonstrated the three swimming together in one direction in an indoor tank and swimming in different directions.
A story by UW about the project provides some detail, including a Robofish photo. A short somewhat technical summary with video links is online at UW’s Nonlinear Dynamics and Control Lab, where the project is based.
Robots like these could be used in groups to track groups of whales, trace plumes of underwater pollution, or explore caves, without having to surface to send data or receive new instructions.
Morgansen has 1994 masters in mechanical engineering from Boston University and a 1999 Ph.D. in engineer sciences from Harvard. Her work has focused on control methods for nonlinear and coordinated control systems, especially those with communications constraints.
The three robots are each about the size of 10-pound salmon. Fin propulsion rather than propellers are used to test for greater maneuverability and lower drag.
Morgansen was inspired by the schooling behavior of large groups of fish, which execute precise maneuvers almost instantly. Working with another researcher, Julia Parrish, associate professor in UW’s School of Aquatic and Fishery Sciences, the team trained some live fish to respond to specific stimuli. They found that even when less than one-third of the school’s members were so trained, the whole school responded on cue.
Morgansen wondered if one underwater vehicle could make the rest of the do something based just on its own behavior. The researchers devised a system of low-frequency sonar pulses (pressure waves) to send messages between the robots. Tests showed that only about half of the information sent was successfully received, but it was enough to coordinate the actions of the group – swimming in one direction, or several.
The next step, starting this summer, will be to have the Robofish trail a remote-controlled toy shark.
