There are lots of theories going around on how the BB-8 droid from Star Wars works.
Over-sized Hamster In The Ball
Dangle some food in front of that oversized hamster and that should do the trick! We have a more humane and simpler design.
Weebles Wobble But They Don't Fall Down
We designed a BB-8 robot based on a counterweight system, like the popular 1970's Weeble toys.
Counterweight System Design
We designed and tested our BB-8 Droid using VR. https://youtu.be/e6iJwWeaj5M
Sphero BB-8 Design
It's essentially the Sphero Ball, a self-balancing, gyro-driven ball inside of there.
Want to build & simulate a variety of bb-8 droids and robots? Try Dynamo For Free www.playdynamo.com
Dynamo is a powerful easy-to-use software for accurately and realistically simulating anything 3D. You are going to love @playdynamo! Stay connected http://facebook.com/playdynamo