The 1-guilla robotic eel’s underwater undulations could provide insight into how eels can migrate thousands of miles without eating. (Image credit: EPFL)
Researchers at EPFL (Ecole Polytechnique Federale de Lausanne) have developed a robotic eel they hope will provide insight into how the real aquatic animal can migrate thousands of miles with an empty stomach. The award-winning 1-guilla robotic eel’s anguilliform design mimics those of flesh-and-blood eels; however biologists are not entirely sure how the fish subspecies can travel long distances without eating. To gain insight into how this is accomplished, the designers explored various physical patterns, along with the reciprocation of energy efficiency and speed.
The three-foot-long waterproof robot features eight motorized segments, a malleable tail fin, and a head unit outfitted with a microcontroller and battery, all of which are contained in a waterproof suit. During testing, a standing-wave motion occurred when the robot repeatedly alternated between an S-shape and its original straight position. This resulted in the robot thrashing about in the water with virtually no momentum. The robot was then reprogrammed to undulate an S-shape that traveled down its body. This gave the robot a “traveling S-shape,” allowing it to move forward. Increasing the amplitude of that traveling S-shape also gave the robot greater speed.
The researchers also found that the primary speed influence came from the robot’s tail fin, specifically by increasing the tail angle to a maximum of 45 degrees. But there’s a trade-off in doing so, as maximum range requires maximum energy usage. After doing a little math, the researchers found that the more the robot’s motion resembled a traveling S-shape, the lower its cost of transport. The researchers hypothesized that overall efficiency in motion, not the highest speed, is the key to how eels can travel long distances without eating along the way.
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