Cornell's Ranger robot walks 40.5 miles on a single charge, doesn't even break a sweat (video)

A few years ago, engineers at Cornell were rejoicing when their Ranger robot set an unofficial world record by walking for 5.6 miles without stopping. Since then, the 22-pound bot has only built up its endurance, to the point where it can now chug along for a full 40.5 miles without a single battery recharge, or an ounce of human assistance. The Ranger pulled off the feat last week, when it completed nearly 308 laps around the university's Barton Hall running track, over the course of more than 30 hours. Engineers say that their bot's stamina has a lot to do with its energy efficiency. The Ranger runs on about 16 watts and uses them more sparingly than most of its mechanized brethren. It also saves juice by swinging its legs more liberally than most bipedal walkers, essentially allowing its limbs to fall freely before re-stabilizing itself. The robot's next challenge, apparently, will be to incorporate automatic steering into its gait, since walking in circles can get understandably dull, after a while. Gallop past the break for the full PR and a video of the Ranger's latest achievement.