Humans are incredibly well-balanced machines. As a species, we've mastered bipedal locomotion, which is challenging for other animals as well as the machines we make. Even BigDog, the reigning champion of robots that walk, does so on four legs. ATRIAS, a bipedal robot made by Oregon State University, recently took its first steps outside onto the uneven ground. And like many an undergrad, it did so with several buddies nearby to make sure it stayed upright.