If we can’t walk and jump off the surface of water, we will make insect-like robots to do so! Scientists have created tiny robots that can emulate the motion of water striders, thereby allowing them to stand on water and jump into the air. The paper entitled, “Jumping on water: Surface tension–dominated jumping of water striders and robotic insects”, has been published in Science.
Humans cannot stand on water, let alone walk on it. Certain strider insects can, though. Scientists have successfully reproduced the insects’ natural ability in robots: they developed delicate machines that can stand on the surface of water, and even jump into the air.
To mimic the water-jumping abilities, the scientists observed natural water striders. They analysed video footage of the insects to understand the mechanism by which they can jump off the water’s surface.
Through a trial and error method, the researchers made a tiny machine that could produce the motions the water striders make.
“Water’s surface needs to be pressed at the right speed for an adequate amount of time, up to a certain depth, in order to achieve jumping,” said one of the authors, Kyu Jin Cho of Korea’s Seoul National University, in a statement. “The water strider is capable of doing all these things flawlessly.”
One of the characteristics of the insect striders that assists them in water jumping is the curved tips of their legs which use a rotational movement that acts as propellant for the animal. In order to maximise the leverage from the water surface, the degree of force to be exerted has to be very precise though.
“Using its legs to push down on water, the natural water strider exerts the maximum amount of force just below the threshold that would break the water’s surface,” said Je-Sung Koh, the study’s co-first author.
“This is due to their natural morphology,” adds Cho. “It is a form of embodied or physical intelligence, and we can learn from this kind of physical intelligence to build robots that are similarly capable of performing extreme manoeuvres without highly-complex controls or artificial intelligence.”
Therefore, the researchers concluded that their robot would have to exert up to 16 times its own body weight on the water’s surface.
They included a “torque reversal catapult mechanism” for their robot.
“The resulting robotic insects can achieve the same momentum and height that could be generated during a rapid jump on firm ground – but instead can do so on water – by spreading out the jumping thrust over a longer amount of time and in sustaining prolonged contact with the water’s surface,” said Robert Wood of Harvard University, a co–author of the study.