Met RHex – the curvy-legged, leaping robot

By Doug Gross, CNN

If you only watch one video today of a robot that hurtles across uneven terrain like a water-walking lizard, does gymnastic back flips and climbs tall objects, make it this one.

If you watch two? Send us the other one.

RHex is a creation of researchers at the University of Pennsylvania who hope it could one day climb rubble in emergency rescue situations or zoom across scorching desert sands with its six whirling, springy legs.

"What we want is a robot that can go anywhere, even over terrain that might be broken and uneven," said graduate student Aaron Johnson, one of those researchers. "These latest jumps greatly expand the range of what this machine is capable of, as it can now jump onto or across obstacles that are bigger than it is."

    RHex (short for "robot hexapod" and pronounced "Rex") is actually more than a decade old, the brainchild of a multiuniversity project. But Penn researchers recently created a new version -- called X-RHex Lite -- that, as its name suggests, is lighter and more agile than previous versions.

    The result: a moving rectangle that has, in effect, been taught robot parkour.

    In the video posted late last month, RHex charges across Penn's campus (with an appropriately epic soundtrack) before showing off an impressive vertical leap, doing several back flips and propelling itself up steps.

    Its most impressive moments, though, might be jumping from one picnic table to another over a gap greater than its own length and flipping up on a tall stone block, grabbing on with its curved front legs and pulling itself upward.

    On robots, legs are more effective than wheels when it comes to rough terrain. But it can be complicated to teach the human-like legs on walking robots how to respond to unpredictable conditions. RHex's simple, one-jointed legs are better suited to getting around obstacles in creative ways, the Penn team says.