Photos: How a robot learns to walk--and limp

Some robots are good at scrubbing floors, others at lobbing a basketball. Generally speaking, though, they're not very good at anything not in a very limited job description. That's why it's worth paying attention to a four-legged machine unveiled Thursday by researchers at Cornell University.

Even though it's pretty much all legs, the robot doesn't know--at first--that it can walk. Rather, it's been programmed to figure that out on its own, starting with only the knowledge of what its parts are, but not how to use them. Through a 16-step process of trial and error, it builds computer models of how its parts might be arranged and how best to move them. "The machine does not have a single model of itself--it has many, simultaneous, competing, different, candidate models. The models compete over which can best explain the past experiences of the robot," Cornell professor Hod Lipson said in a statement.