11" BB-8 prototype BB-8 robots

Building BB-8 Part 2 – The Startening

BB-8 presents some interesting engineering challenges. How do you get a robot that is basically a head balanced on a sphere to move around? How do you keep the head from falling off, and how do you move it independently from the ball? How can you make a robot that is a hemisphere on top of a sphere able to express emotions and interact with the world?

Nobody completely understands how the prop builders have made BB-8, so everybody who is building their own BB-8 is figuring it out themselves. The BB-8 Builders Club is collaborating on designs: everybody working independently (including me) is sharing what we learn. It’s open group prototyping, and it’s a fantastic way to work.

The Club’s best guess is that BB-8’s main “body” sphere is 50.6 cm in diameter, and the “head” hemisphere is about 30.0 cm in diameter. If you’re in the US, you can buy plastic hemispheres and spheres from California Quality Plastics; a pair of 50 cm diameter hemispheres will set you about about $500 USD. That’s way too much for me to spend on a prototype, and a 50 cm diameter is pretty big to have sitting around the house. I decided to build my prototype inside something smaller and cheaper.

I poked around for a while and finally settled on a run-about exercise ball for rats, which I picked up at my local pet store. I was lucky that the owner had rats, because I didn’t even know that the bigger run-abouts were a thing. The hamster-sized balls (about 17.5 cm diameter) are too small to work in comfortably–especially with the motors I have sitting around–but the rat-sized balls (about 29 cm in diameter) are perfect. I picked up the run-about for about $35 CAD. And I’m off!

I’m going to try to build the robot only from parts I have on hand. If something seems like a totally weird or completely awesome choice, it could just be because it was what I had sitting around. For example, I wish I could take credit for the choice of control over Bluetooth, but  it was because I had an Arduino-compatible Bluetooth module and couldn’t find my Xbee shield.

Next up, I’m going to dig through my old parts and build a drive for BB-8.

11" BB-8 prototype BB-8 Making Programming robots

Building BB-8 Part 1 – The Idea

Photo by Chris Pirillo,
The world’s new favourite spherical droid

In case you’ve been off in space rescuing Matt Damon, let me mention that new Star Wars movie is out. For many of us who saw the original in the theatre, and then survived the egregious abuse of fan loyalty that was the prequels, The Force Awakens was like a big apology hug from JJ Abrams. “We’re sorry. Here’s the movie you deserved.”

Much like the original series, there’s a character in the new film that’s captured  the hearts of fans. The original movies had R2-D2, the helpful astromech droid who tolerated Luke’s complaining to deliver the plans for the Death Star and save his ass many times. The Force Awakens  has BB-8, an equivalently helpful droid with a giant personality who you just want to hug. Really. You want to hug him. He’s adorable.

As a roboticist, I didn’t just want to hug him; I wanted to build him. I know several people who have build R2 and other astromechs over the years; those always seemed cool to me, but it all looked pretty straightforward. When I saw BB-8, a spherical droid whose head floats above his body, my immediate reaction was “now THAT would be a  fun robot to build.”

My friend Matt introduced me to the BB-8 Builders Club, and I discovered that there were several people working on building BB-8 replicas, and some had already built them just based on what they had seen in trailers. Most notably, there’s James Bruton of, who in my opinion has built the coolest BB-8 out there… and published all of his files and code online. Go check it out.

But! The roboticist in me doesn’t want to follow instructions for what somebody else has built: she wants to figure it out herself. With this comes new skills (3D printing, 3D modelling), using old skills in interesting ways (mechanical engineering, electronics, programming, prototyping), and a fun little project.

I’ve been working on my BB-8 prototype for about a week now. These blog posts will be my attempt to chronicle the process and what I’ve learned. It will not be a guide to building BB-8; I can’t really do that with a prototype anyway, and I’m also going to tell you about the mistakes I’ve made. This is what it looks like to build robots. Feel free to follow along!