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Robot Fish Leads Organic Fish

Researchers from the Polytechnic Institute of New York University set out to discover what it would take to create a robotic fish that was accepted as another member of the shoal, by 'real' fish. They conducted a series of experiments with a swarm of golden shiners in a water tunnel with the water moving at different speeds as controlled by external pumps.

The robotic fish used in the experiments was fairly primitive, essentially a radio controlled waldo with actuators at the fin and tail points to allow it to swim with varying degrees of natural motion.

In this Alife experiment, the researchers found,. Fairly predictably, that if their robot fish just lay still in the water, the other fish ignored it. But, when the fish began to move under its own power, the interesting things began to happen.

In nature, fish positioned at the front of a school beat their tails with greater frequency, creating a wake in which their followers gather. The followers display a notably slower frequency of tail movement, leading researchers to believe that the followers are enjoying a hydrodynamic advantage from the leaders’ efforts.

When the robotic fish assumed the swimming movements of a golden shiner, its movement and overall size was similar enough to the other fish, that they seemed to treat it as part of the shoal; allowing it to swim with them with no signs of alarm.

Further, when the robotic fish increased the frequency of its tail propulsion beat, regardless of the strength of the current around it, the rest of the shoal formed up behind the robot fish, and followed in its wake, wherever it directed that they go.

This has obvious implications, both in the field the researchers are striving for – the use of biomimetic movement patterns to integrate robots into nature as leaders to control the movement of natural swarms and herds; and as a general Alife item of some note. If it is that simple and easy to get a swarm of fish or possibly even a flock of birds (which is the researchers' next intended target) to follow the leadership of a single robotic leader following a simple algorithm, then it should be quite simple to replicate artificial life in a simulation, and form and disband swarms dynamically, following the same simple rules – without any worry that your artificial swarms might be diverging from how such swarms behave in nature. As a bonus, it means swarms should be replicatable far more cheaply in relative computational terms, than has been done to date.

The researchers posit that robotic leaders could help lead fish and other wildlife that behave collectively — including birds — away from toxic situations such as oil or chemical spills or human-made dangers such as dams. Other experimenters have found success in prompting wildlife to move using non-living attractants, but the researchers believe this is the first time that anyone has used biomimetics to such effect.

References

What Makes a Robot Fish Attractive?

Fish and robots swimming together: attraction towards the robot demands biomimetic locomotion

Dictionary: Biomimetic Locomotion

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