In order to create the mechanisms for the robot to successfully launch itself from the water’s surface, the researchers from Seoul National University and Harvard University analyzed how water striders (Gerridae) were able to jump on water.
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Among the unbelievable abilities of water strides is the fact that they can launch themselves from the water surface with the same ease as from the firm ground.
Water striders use this surface tension to their advantage because of their highly adapted legs and distributed weight. To get the little machine insect jumping, a spring-like device in the “body” was heated using a small heating wire, causing a change in stiffness and activating the leap.
“Normally, jumping requires a large force to be applied to the surface that you are jumping on”, Kim says.
The robots can jump on land as well as water. As with many robots inspired by animals, this one exists mostly to help researchers understand the intricate jumping mechanisms we see in nature.
By observing water striders using high-speed cameras, the scientists noticed that the insects do not simply push down on the water, but gradually accelerate their legs so as not to break the surface tension.
The researchers incorporated all of these strategies and others into the robot’s design and were able to create a tiny robot that is very good at jumping off of water.
The prototype robot weighs just two-thousandths of an ounce (68 milligrams) and has a body measuring 3/4-inch (2- centimeter) long.
Je-Sung Koh of Seoul National University and his colleagues have copied the unbelievable water strider to build a robot that can jump on water, without sinking. This heat-activated spring is fine-tuned so that it pulls the bugbot’s flexible, curved-at-the-tip legs inward and downward at a speed just below that that would pierce the water’s surface (last 15 seconds of video), thus producing a successful leap rather than a flailing flop.
The striders also sweep their legs inward before each jump, to maximise the amount of time they touch the surface, which increases the force of their pushes. The achievement, described in Science today, means that an army of small, robotic creatures might one day help search for flood survivors – or they could end up being used to creep on your enemies, according to the researchers.
They added: “A small insect-mimicking robot can not perform complicated tasks as large robots [like humanoids] aim to do”.
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‘The results suggest an understanding of the hydrodynamic phenomena used by semi aquatic arthropods during water jumping and prescribe a method for reproducing these capabilities in artificial systems.’.
