We're not sure what brand of batteries it was using, but the Cornell Ranger robot just kept going and going April 3 when it set an unofficial world record by walking nonstop for 45 laps -- a little over 9 kilometers or 5.6 miles -- around the Barton Hall running track.

The robot was developed by a team of students working with Andy Ruina, Cornell professor of theoretical and applied mechanics. Unlike other walking robots that use motors to control every movement, the Ranger emulates human walking, using gravity to help swing its legs forward. The goal of the research is not only to advance robotics but also to learn more about the mechanics of walking. The information could be applied to rehabilitation and prosthetics for humans and even to improving athletic performance.