A robotic leg moving through water creates similar patterns to the motion of krill as they swim, and could be used to study the role these animals play in their marine environment.
Krill are small crustaceans that serve as one of the most important and abundant ocean food sources. They form large swarms on the ocean surface and dive down when threatened by predators, taking nutrients, carbon and oxygen with them, but the dynamics of this behaviour aren鈥檛 fully understood.
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To better understand how krill move, at Brown University in Rhode Island and her colleagues built a 3D-printed microrobot known as RoboKrill. It is about 10 times larger than real krill 鈥� which are up to 5 centimetres long 鈥� and is made of a leg with two gear-powered appendages that function like krill鈥檚 swimmerets, the swimming legs they have on their abdomens.
鈥淚t鈥檚 hard to keep [krill] in the lab,鈥� says Martinez Wilhelmus. 鈥淗aving a system that allows us to test different configurations in a lab environment could accelerate the process of understanding their role in their environment.鈥�
Martinez Wilhelmus and her team measured the angle of RoboKrill鈥檚 appendages with a high-speed camera as it moved forwards through the water, and found it produced a similar pattern to real krill. The appendages are also adjustable and can be made to produce the swimming dynamics of other organisms that swim like krill.
RoboKrill is held underwater by a geared arm and can鈥檛 yet swim on its own, but the researchers aim to eventually use it to monitor krill swarms in the wild by sending it into colonies to swim with the creatures that inspired it. It would need to be untethered and miniaturised first. RoboKrill could also be used one day to explore ocean ecosystems, says Martinez Wilhelmus, once it is incorporated into a self-sufficient robot.
鈥淥ur long-term goal is to make an autonomous underwater vehicle, a compact one, so we wanted to minimise the number of links and be able to make everything enclosed,鈥� says Martinez Wilhelmus.
While monitoring live krill colonies is beyond the capabilities of the current prototype due to its size, it could still be useful as an inspiration for robots designed to explore marine environments.
鈥淭hey have developed an elegant mechanism to better capture the complex motion of the krill swimming legs,鈥� says at the University of South Florida. 鈥淭his could lead to better and smaller robotics that are more efficient and can fit into hard-to-reach places.鈥�
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