‘Bug’ inspired robot that jumps on water

When making their spectacular jumps, these insects can produce enough vertical drive to jump from the water, which is a motion that normally requires high momentum. Fortunately, these robots were designed not for surveillance but for science. In order for the robot water strider to do this, engineers equipped it with a “torque reversal catapult mechanism”, which mimics the way fleas jump.

Could a robot leap across the surface of water? The prototype robot glider can exert up to 16 times its own weight against the surface water without sinking, with relatively simple controls. The work done on previous bots, combined with the team’s study of water striders in nature, helped them design their running and leaping little machine.

Water striders are particularly evolved for the ability to jump off water. Now that they’ve cracked the code of creating a robot that can use the surface tension of water to propel itself, entirely new possibilities have opened up. “In contrast to jumping on solid ground, a large driving force and fast stroke in the jumping leg do not guarantee a high takeoff velocity on the water surface, especially for small insects”.

Also, the researchers observed that the water strider’s long legs accelerate gradually such that the water surface doesn’t retreat too quickly and lose contact with the legs. He and his colleagues determined the robot needed to have its legs in contact with the water until the last possible moment to make leaping possible.

The robotic version uses the same forces to jump as the water strider – pushing off without breaking the surface. We have complex quadrupeds that can run and jump over obstacles like an animal as well as insect-inspired robots that can move easily through fields of debris.

Researchers in Korea have developed a robotic insect which is able to jump on the surface of the water.

Finaly, Dominic Vella, an applied mathematician at the University of Oxford, says “the result is strikingly similar to the jumping of the real water strider”. But even if they’re not, the development was a fruitful exercise in confirming what had previously just been a theoretical understanding of surface tension and locomotion.

Cho and his team spotted that water striders rotate their legs to maximise the interaction time between the legs and the water, which means there’s more time and interaction to transfer momentum.