New robotic system mimics how frogs jump out of water

A team of researchers has been investigating the way that some marine animals manage to launch their bodies above the surface of water. The experts designed a robotic system that mimics the fluid dynamics used by frogs and tiny crustaceans as they jump out of the water.

Sunghwan Jung is an associate professor of Biology and Environmental Engineering at Cornell University, who is conducting the research with his student Brian Chang.

“We collected data about aquatic animals of different sizes – from about 1 millimeter to tens of meters – jumping out of water, and were able to reveal how their maximum jumping heights are related to their body size,” said Professor Jung.

Aquatic animals move in and out of water for different reasons, such as evading predators or catching prey.

“But since water is 1,000 times denser than air, entering or exiting water requires a lot of effort, so aquatic animals face mechanical challenges.”

As an animal jumps through water, mass is added to it. This extra force, referred to as “entrained water mass,” limits the height to which the animals can jump.  

“We’re trying to understand how biological systems are able to smartly figure out and overcome these challenges to maximize their performance, which might also shed light on engineering systems to enter or exit air-water interfaces,” said Professor Jung.

Most marine animals are streamlined and water just slides off their bodies, limiting the effect of entrained water mass.

“That’s why they’re such good jumpers. But when we made and tested a robotic system similar to jumping animals, it didn’t jump as much as animals. Why? Our robot isn’t as streamlined and carries a lot of water with it. Imagine getting out of a swimming pool with a wet coat – you might not be able to walk due to the water weight.”

Professor Jung explained that the system may ultimately be used for surveillance near water basins.

The research was presented at the American Physical Society (APS) Division of Fluid Dynamics 71st Annual Meeting.

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By Chrissy Sexton, Earth.com Staff Writer