Disney has been trying to get mobile character robots working for years. They had Danny Hillis, from Thinking Machines Corp, for a while, and they got Lucky the Dinosaur[1] out of that. But Lucky was not really balancing; the stability comes from the cart the creature seems to be pulling.

It's not that it can't be done; it's making it completely idiot proof that's hard.

[1] https://www.youtube.com/watch?v=oBLwyxqx4mk