A Robot That Walks on Water

Yun Seong Song and Metin Sitti from Carnegie Mellon University have created a water-strider robot based on the insect, which uses surface tension to literally walk on water.

(Left) Photo of the water strider insect. (Right) Photo of the 1-gram robot on the surface of the water. A, B, C, D: supporting legs; E and F: actuating legs; G: body with on-board electronics and power source; H: middle actuator; I and J: right and left actuators. Image credit: Yun Seong Song and Metin Sitti. ©IEEE 2007

"For locomotion, the water strider insect creates a sculling motion with specialized sculling legs. The robot functions the same way. Three piezoelectric actuators, when attached to the legs in a T shape, create both vertical and horizontal motion to cause the elliptical sculling motion required to move.

Because the piezoelectric actuators provided only a small deflection, an amplifier was needed to create large strokes. To achieve this, the researchers used a resonant frequency with a vibration mode favorable to generating the sculling motion to drive the actuators. While a water strider insect can move at speeds of up to 1.5 m/s, the first robot still achieved a forward speed of 3 cm/s, and could also turn, rotate and move backwards."

More details here.