The robot that jumps on water

Je-Sung Koh of Seoul National University and his colleagues have copied the awesome water strider to build a robot that can jump on water, without sinking.

Their legs are long and thin, allowing the insect’s weight to be distributed over a large surface area.

Curiously, the insect-like machines jumped even better on water than they did on the ground-a counterintuitive result, the authors write, that can possibly be explained by lower levels of leg vibration on water than on land, translating to greater vertical kinetic energy.

In this latest study, researchers unveiled a novel robot insect that can jump off of water’s surface.

When powered up for a jump, the spring releases, but slowly, dragging the ends of robot’s body and its 5cm insect-like legs downward with gradually increasing force to the limit the water surface will withstand. But previous robots weren’t quite as faithful to the water striders that they were modeled after; the Waterloo robot used wide paddles for its jumps and weighed about a thousand times more than a water strider.

They observed how the long legs of the bug helped it accelerate in a gradual manner, so that the surface of the water does not retreat quickly and lose contact with its legs. Talking robot on trans-US hitchhike stuck in Boston for 7 days!

The film also revealed the water strider sweeps its legs inward in order to maximise the time it can push against the surface, to boost the overall force. As with many robots inspired by animals, this one exists mostly to help researchers understand the intricate jumping mechanisms we see in nature.

From left, Seoul National University professors Ho-Young Kim and Kyu Jin Cho observe the semi-aquatic jumping robotic insects developed by an SNU and Harvard team. These insects not only jump, though, but also skim along the water’s surface.

Jumping on water is hard.

To produce the body of the robotic insect, “pop-up” manufacturing was used to create folded composite structures that self-assemble much like the foldable components that “pop-up” in 3D books. You may be the kind of person that believes walking on water is possible, but surely we can all agree that jumping on water-this-this is surely a feat of supernatural fitness, one would think.

This work was supported by the National Research Foundation of Korea, the Defense Acquisition Program Administration’s Bio-Mimetic Robot Research Center, and the Wyss Institute.