Since the little guy debuted on stage at Star Wars Celebration in April, droid BB-8 captured our hearts.
J.J. Abrams' insistence on practical effects in Star Wars: The Force Awakens meant that a brand new droid designed for the film would have been easier to make inside the computer — but just like R2-D2 and C-3PO, Abrams wanted the new droid to be real. A genuine physical creation that could actually move and perform.
There was just one problem: BB-8 took his design inspiration from a quote by the late Ralph McQuarrie, in which he described his original idea for R2-D2. "I thought of him as running on a giant ball bearing. Just a sphere, a circle, wheel-like. He had gyros so he could go in any direction on this ball." That's pretty much an exact description of BB-8.
Such technology was impossible to achieve back in the '70s when Star Wars was made, and you'd be forgiven for believing it's impossible today as well. But as we all know now, Lucasfilm and Disney found a way to make it work, thanks to some hands-on help by Disney CEO Bob Iger.
A pair of self-professed geeks have built a website called How BB-8 Works, where they go into colorful, entertaining detail to explain their educated guess on the subject at hand. Their theory is based on a patent they discovered, owned by Disney, for a "magnetic spherical balancing robot drive."
In plain English, BB-8's ball-shaped body houses a skeleton that always stays balanced, kind of like a Segway, using a bunch of complicated stuff like counterweights, gyroscopes and that sort of thing. This allows the little droid's remote handlers to maintain precise control over him, so he doesn't roll away. The internal skeleton has its own motorized wheels, which are what the remote is actually controlling.
The head floats over the body via some complex magnets. The magnets inside the body are attached to an armature that allows BB-8's head to move in a way that seems independent of his body's orientation. A really nifty animation on the website (screenshot above) lets you peel back BB-8's shell to look inside and see how the mechanisms work. You can even grab the animation and manipulate it to get a better look at the droid from any direction.