Published on June 12th, 2012 | by Tina Casey1
New Robot Mimics a Fish Behaving Like a Boy Scout
Boy Scouts, well known for helping that apocryphal little old lady cross the street, have become the inspiration for a new kind of rescue robot that will help guide fish away from oil spills and other aquatic hazards. The new robot-fish is under development by an interdisciplinary team of scientists from the applied technology institute NYU-Poly in New York City.
Plenty of other robotic fish in the sea
The new mechanical fish adds an interactive twist to a growing list of small aquatic robots under development.
Until now, these devices, such as a jellyfish-like robot (aptly named Robojelly), robotic bubbles, and a new fish-shaped device recently deployed in Spain, are generally not designed to call forth particular behaviors in live sea creatures.
Their primary functions are underwater exploration, surveillance, and environmental monitoring. Their resemblance to fish and other aquatic life, if any, derives from design requirements related to durability, agility, and propulsion.
Biomimicry and interactive robotic fish
The NYU-Poly robot takes the biomimicry angle up a level by attracting live fish to itself and stimulating them to follow its lead.
For its latest study, the research team designed an oversized zebrafish of about six inches in length, compared to one inch for a typical adult zebrafish.
They painted the robot with the lengthwise stripes that give the zebrafish its name, and to guarantee attractiveness they gave it proportions that mimic the come-hither look of a fertile female, which among zebra fish is appealing to both genders.
As the experiments revealed, though, color cues and sexual availability are just two of several variables that can influence the behavior of live fish.
Earlier experiments had shown that live fish will follow a robot based simply on the motion of its tail, which creates an attractive wake. To eliminate that variable, in this new set of experiments, the team segregated the robotic fish in its own compartment.
Some of the results were fairly straightforward. When separated by a barrier, the live zebrafish preferred to swim near the robot rather than disperse around their part of the tank, clearly indicating that they would respond to visual cues without the creation of a wake.
Second-best proved to be no substitute for the real thing, though. When a new, live zebrafish was introduced to another compartment of the tank, the other zebrafish quickly deserted the robot for its flesh and blood rival.
Sound also proved to be a factor. In a darkened tank, the noise from the robot’s motor disagreed with the live fish, much like a snoring partner can make things disagreeable in bed, and they decamped to an empty compartment (which, apparently, stood in for the living room couch).
Next steps for robotic zebra fish
According to Maurizio Porfiri, associate professor in the NYU-Poly Department of Mechanical and Aerospace Engineering, the noise of the motor is a significant design obstacle, and developing a silent means of propulsion will be priority as the project moves forward in development.
This early version of the robot also lacks the autonomous behavior capabilities that are rapidly being developed in advanced robotics.
Autonomous behavior is particularly important for rescue robots, which are deployed in environments that humans cannot navigate or survive in.
For example, the Navy is developing a firefighting humanoid robot that will respond to hand signals and other cues from a live person who provides directions to the general area of a fire. The robot can then act autonomously to draw closer to the source and deploy fire-suppressing agents.
According to Porfiri, future versions of the robotic fish will include sensory interfaces and artificial intelligence, in order to provide for autonomous interaction between the robot and its live charges. Once endowed with artificial intelligence, the fish could also be adapted for use in a related field of advanced robotics, in which “swarms” of small devices are designed to coordinate their behavior autonomously.
The results of the study are available in the academic journal Bioinspiration and Biomimetics, under the title “Zebrafish Response to Robotic Fish: Preference Experiments on Isolated Individuals and Small Shoals.”
Image: Courtesy of NYU-Poly
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