Roboticists showcase tiny, frog-like robot that can hop across wet surfaces and swim

Inspired by frogs, roboticists have developed a tiny robot that can hop across wet surfaces and swim. Published in the journal Science Advances on September 18, the study explores how twisting elastic rods can produce a snapping motion that enables the robot to move efficiently. The 3.4-ounce robot, roughly the size of a playing card, hops about three body lengths per second, propelling itself forward with short jumps.

Assistant Professor Xiaonan Huang of the University of Michigan explained that by programming the energy storage and release of elastic structures, small robots can achieve powerful, repeatable motions without relying on large motors or complex control systems. When a flexible rod bends and its ends are rotated, it can eventually snap, releasing built-up tension.

The researchers used computer modeling and experiments to determine the optimal shape for this motion, which resembled a coiled spring. The team then designed and built robots using these snapping rods, connecting them to a rotating motor and twisting the rods until they snapped. The final prototype featured a frog-like design with snapping rods at the rear, capable of hopping over various surfaces, including water.

With further development, this technology could enable robots to navigate cluttered terrain, overcome obstacles, and operate across both land and water.