R2-D2 has some real competition now when it comes to being the galaxy’s cutest droid. Yesterday, at a press conference for the upcoming Star Wars movie The Force Awakens, a new bot named BB-8 rolled on stage and stole our hearts.

Unfortunately, it also ground productivity to a screeching halt around the Make: office, as we all tossed around theories on how the robot works.

Like us, you probably want to get right to work building your own BB-8 droid. Unfortunately, the people who are best equipped to tell us have likely sworn secret oaths to Star Wars’ producer, Disney, a company who notoriously guards these kinds of secrets very tightly.

The new BB-8 droid from Star Wars takes the stage at yesterday's Star Wars Celebration event in Anaheim.

The new BB-8 droid from Star Wars takes the stage at yesterday’s Star Wars Celebration event in Anaheim.

The good news is that I’m sure the Maker community will figure this out. In fact, I’d be surprised if we don’t see a working prototype before the weekend’s through.

Better yet, we can maybe even improve on the BB-8 we saw on stage. For all the magic of its movements, there’s still room for improvement. Maybe BB-8’s camera eye could be hooked up to an FPV rig for some RC robot racing. Maybe a versions should be made with a boombox concealed inside. Maybe all of the above.

To help you on your quest to build your own BB-8, here are links to two DIY robot tutorials that should help.

And for what it’s worth, my theory (subject to change on a minute-to-minute basis) on how BB-8 works is that the ball works very much like an omnidirectional or holonomic robot  trapped in a ball (aka, the XKCD robot pet) while the head works like a ball-balancing bot. By talking to each other in active cooperation, the head can tilt to a limited degree, trusting that the ball will counter-balance the shift in weight.

That said, I’m open to the idea of being completely wrong on this. Jalopnik, for example, theorizes that the head is a lightweight shell controlled by an articulating magnetic arm within the ball. I would love to hear what you all think. Leave a comment, share your links to other projects, and let’s get this thing built! 

Ball Balancing Robot

This tutorial on Instructables for making an RC-controlled ball-balancing robot may look like the BB-8 holy grail at first glance. But if you’re looking to get that telltale BB-8 head tilt, then this bot is only part of the equation.

This robotic balancing act is pulled off using a combination of gyroscopic sensors and accelerometers to sense microscopic shifts and counteract them using 3 or more omnidirectional motors.

Ball-balancing robots can be used actively to push themselves around on their bouncy perch, or they can be used passively, remaining upright while being pushed around by another force. For example, this video shows a ball-bot acting as a high-tech wheelbarrow, loaded up with bricks and wood, being pushed around by its operator.

But whether this type of robot is used to actively drive the ball it sits on, or passively react to being moved by an outside force, it must fight to remain continuously perched at the very top of the ball at all times or risk falling over. The fact that BB-8 can tip its head without falling down points to the idea that there is another technology at play.

R/C Omniwheel Floor Robot

Omniwheel motors aren’t just good for staying on top of a ball. They’re used for ground applications as well, including forklifts, battlebots, and this great RC bot from Make: issue 40. A complete kit is also available.

The R/C Kiwibot from Make: issue 40 uses an omniwheel motor system.

The R/C Kiwibot from Make: issue 40 uses an omniwheel motor system.

Many have pointed out that the BB-8’s ball moves like a giant version of the Sphero (coincidentally, the company made a giant Sphero as a practical joke in 2013), and there’s good reason to believe that’s true. Fortune Magazine connected the dots and made an educated guess that Sphero was actually contracted to help with the design of BB-8 (if so, get ready for the must-have holiday toy).

And while the Sphero does not use omniwheel motors (it’s more like a two-wheel Segway motor trapped in a shell), its motion can be easily simulated by placing an RC omniwheel bot in a ball. So whether or not the BB-8 we saw on stage uses an omniwheel bot to drive the ball, the bottom line is that the same effect could be achieved by using one. And best of all, the internet is littered with instructions for making omniwheel robots. It’s a much shorter path to getting results than reverse engineering a Sphero.

Final thoughts

Like many Hollywood secrets, we may never know exactly how the BB-8 was made. And as I said, my best guesses could be way off base. I’m just a tinkerer.

Really, the most exciting thing about BB-8 is the outpouring of curiosity and inventiveness that it inspires. So as you set about to make your own homebrewed version of this adorable bouncing bot, help to spread the excitement of inventing and robotics by sharing your work (the flops and the breakthroughs) and contributing to the conversation.