How could a robot fish possibly act in a way to lead flesh-and-blood fish schools? It turns out that leader fish have definable characteristics:
Dr. Porfiri chose to start with the bait fish swimming in his tanks because their information-sharing is particularly rich: They make their decision on whether to school based upon what they see and the flow that they feel, which can be studied using fluid dynamics. Fish leaders, according to biologists’ published literature and Dr. Porfiri’s observations, beat their tails faster, mill about and accelerate to gain attention, gather a school and lead it.
Using a shallow, donut-shaped tank and cameras, the NYU-Poly team began a mathematical journey into fish schooling in one-dimensional environments. They recently reported their results from this study in the Journal of the Royal Society Interface. Meanwhile, they built silent, remotely controlled, fish-like robotic swimmers that fit in the palm of a hand. These first robots can “swim” along a plane; the next step is to create robots that can dive and surface.
To engage live shoal mates, Dr. Porfiri wanted to give the robot other fish qualities. Foremost, it would have to swim silently, and its locomotion would have to closely match that of live fish. To achieve these goals, he employed ionic polymers that swell and shrink in response to electrical stimulation from a battery, propelling the robot.
Science fiction fans have been thinking about robotic fish for quite a while.
In his 2002 story Slow Life, science fiction author Michael Swanwick writes about robot fish who help explore distant worlds:
The Mitsubishi turbot wriggled, as if alive. With one fluid motion, it surged forward, plunged, and was gone.
Lizzie switched over to the fishcam.
Black liquid flashed past the turbot’s infrared eyes.
Straight away from the shore it swam, seeing nothing but flecks of paraffin, ice, and other suspended particulates...
(Read more about the Mitsubishi turbofish)
Although Dr. Porfiri's work is still in the research stage, it's not too early to hope that one day robotic fish could lead their flesh-and-blood brothers to safety in the event of an environmental catastrophe like the one unfolding in the waters of the Gulf of Mexico today.