How Two 'Star Wars' Fans Unearthed the Secrets of BB-8 (Maybe)

From the moment BB-8 made its debut in the teaser trailer for Star Wars: The Force Awakens, fans have been trying to figure out how the rolling robot works. Once the world learned that the droid was a real prop, not a CGI effect, speculation went into overdrive. Lucasfilm has yet to reveal how BB-8 operates — how does it stay upright while rolling? Is the head attached to the body? But two Star Wars fans in Spain, Carlos Sánchez and Emilio Gelardo, believe they have cracked the code.

Related: Read more about ‘The Force Awakens’

“Truth is, 80 percent of the information was already out there. So our job was putting all those pieces together and filling in the gaps,” Sánchez, a web developer with a background in engineering, tells Yahoo Movies.

On their website HowBB8works.com, Sánchez and CG artist Gelardo have created a 3D model of the rolling droid, with a toggle that allows visitors to see inside the ball. The model illustrates two possible interior mechanisms for the robot: One that has the head attached to a vertical mast, and another that positions the head on a rotating, arc-shaped axis. (In both designs, the head is magnetic, and the sphere moves with four internal wheels and orients itself with a gyroscope.)

Watch our video of BB-8′s live debut at Star Wars Celebration Anaheim.

Sánchez and Gelardo arrived at their design by doing exactly what thousands of other curious Star Wars fans were doing: Reading everything they could find about BB-8 online. “We found some very cool articles about it, but they were all missing something; none really explained, in-depth, the full story behind BB-8,” says Sánchez. They set out to fill in the gaps themselves. And that’s when they discovered the smoking gun: a patent for a “magnetic spheric balancing robot drive” filed by Disney in 2010.

“Like most patents when they’re approved, it’s public,” says Sánchez, who discovered the patent via the fan site StarWars7News.com. “I was surprised that no one really paid much attention to the patent, considering all the valuable information it contained.”

That “valuable information” might not be apparent to a layperson, since patents aren’t easy reading. But Sánchez has a degree in engineering, and Gelardo — who specializes in CG renderings of Star Wars ships and vehicles — has an impressive grasp of technical knowledge. “It’s amazing how much he knows about these devices, because when he builds them, he actually needs to understand how they work,” Sánchez explains.

An image that compares the BB-8 with the foot of the AT-AT (Emilio Gelardo)

Using the information from the patent, along with well-publicized information about the “Sphero ball” (a ball-shaped toy manufactured by robots company Sphero, which collaborated with Disney on the BB-8 design), Sánchez and Gelardo created their two possible versions of BB-8. It was Gelardo who devised the mechanism with the rotating axis, which is actually based on the design for the AT-AT vehicles created for The Empire Strikes Back. (See the comparison picture above.)

Launched in May, HowBB8Works.com quickly went viral. Sánchez says that response has been overwhelmingly enthusiastic, much to his surprise. “We’re proposing two different mechanisms, right? So at least one of them must be wrong!” he acknowledges. Thanks to suggestions from knowledgeable fans, the site creators are now tweaking their design, and will soon publish an updated 3D model “that’s going to be probably even more accurate than what we’re showcasing right now.”

Sánchez and Gelardo have no plans to turn their design into a real-world prototype, though they’ve received many emails from fans interested in building one. But they do intend to build more websites like HowBB8Works.com, “for other items in pop culture that we believe people want to know about,” Sánchez says. “We’re already discussing what our next move will be.”

Although they’ve received feedback from plenty of Star Wars fans, Sánchez and Gelardo have not been contacted by Disney or Lucasfilm. (It’s not outside the realm of possibility: After all, Lucasfilm hired two amateur droid builders to help with the new R2-D2 in The Force Awakens.) “I guess I thought if this [design] is good enough, it will eventually get to them,” says Sánchez. “And I will be interested to know what they think.”