Hacking Roomba

In the Diggnation #71 podcast, Alex and Kevin were discussing some prequel to the current very awesome Battlestar Galactica series and one of them said something like “you know how it all starts don’t you? Roombas. When they’re bumping into your shins they’re really trying to take over the world.” And then they showed a little CGI mockup of a Cylon Roomba. Well, I thought, that can be made in real life. No computer graphics needed.

Here’s how to make your very own Cylon Roomba. Like the projects in the book, this one doesn’t harm or permanently modify your Roomba. After you’re done playing Cylon with it, you can turn it back into a music box, painter, or even a vacuum cleaner (I hear they do that too). You don’t need the book to do this project, but it might help if you’re not that experienced with electronics and programming.

(All photos below are available in higher res in this flickr photo set)

The Five-minute Version

The project below is fairly complex compared to many other Roomba hacks, since it requires you to build a circuit, a physical structure, and write code. If you don’t want to go through all that, you can get one of those $20 “LED grill scanners” from your local auto parts store and plug it into the Roomba’s power jacks.

It doesn’t look nearly as cool, I think, but it is quick-n-easy. Time for the real deal.

The Circuit

An Arduino microcontroller board is used as a replacement brain for the Roomba and also controls which LEDs light up when to recreate the Cylon “scanning”. To connect an Arduino to a Roomba, use something like the Roomba prototyping cable and it will plug directly in.

The LED driver is a bit more complex. To address 16 independent LEDs, two 74HC595 parallel out shift registers are used. The circuit below is a copy of the one on the Arduino site about using the 595.

You could hook LEDs directly up to the outputs of the 595s, but to complicate things, you can stick another circuit between the 595s and the LEDs. This extra circuit creates a subtle fading of the LED’s light as it’s turned off. This replicates somewhat how the incandescent lights worked in original Cylon costume. The idea for this was stolen from a great page on how to make a Cylon jack-o-lantern.

You can wire it up in whatever way you’re comfortable. The circuit does just barely fit on a little Radio Shack breadboard, but it’s very cramped.

Once you’ve tested the board by itself, you can hook it up to an Arduino and see if it works with the code. You can use any LEDs, they don’t have to be mounted in the eye piece yet.

Eye Construction

The LEDs needed to be housed in some sort of eye piece that could fit on the front of the Roomba. Because of the narrow emission pattern of most LEDs, adding a light diffuser would also be good. There are many robust ways to go about this, but I wanted something that I could build fast and cheap.

I decided to used a lucite light panel from the hardware store ($6 for a 3’x4′ sheet) and cut it into appropriate shapes with a Dremel. The pieces would be assembled with hot glue. The lucite panel was nice because it was designed as a light diffuser, solving that problem. It’s also lightweight and flexes. This flex lets you make the curved from by bending a straight piece around a curved spar. It also makes mounting the LEDs much easier as you can work on a straight piece for all the drilling and gluing.

The Software

The software to test the eye by itself is a pretty straight-forward adaptation of the software on the Arduino ShiftOut tutorial page.
– CylonEyes.pde

The first version that integrates the cylon eye and a rudimentary custom Roomba behavior is called RoombaCylonAlpha. It just drives around bumping into things and turning, “scanning” with its eye and turning all red when it does run into things.
– CylonRoombaAlpha.pde

Assembling It All

Once everything is built you can mount it on the Roomba. While the LED driver board is about as big as an Arduino shield, it’s not one so it can’t just plug on. But you can use a stand-off to connect the two boards together.

And then you can start doing silly parodies of your favorite BSG episodes.

(revver link, youtube link)