This project is a motorized mannequin arm and wooden planchette that spells out tweets it receives on a ouija board.
## FAQ (Fully Anticipated Question):
* Why does it have a microcontroller driving the motors instead of using the Raspberry Pi GPIO?
I had an Adafruit Crickit board that I wanted to play with, and the idea for the Ouija Robot is what I came up with.
As I was playing with my original cardboard prototypes, I realized that it's very difficult to actually see what is being spelled out without carefully watching the hand. So I added the Pi with a display for that purpose. Adding a Pi also meant that I could have it read from an Internet source easily instead of having a few pre-programmed messages as I had intended.
This definitely could all run off of the Pi alone but I'd already done the work with the Crickit and I liked the symmetry of circuitry on each side of the arm.
(More details to come shortly!)
Hollow plastic arm from Amazon used in jewelry store displays
Laser cut on wooden plank
Used for servo/light control
Raspberry Pi with 3.5" TFT display
Used to interface with Twitter and display messages
I started by using a laser cutter to engrave the ouija board. The letters are arranged on a slight curve so that the arm can sweep across them hitting all of them. (The planchette still needs to be able to move to hit everything, but I wanted to minimize that as much as possible to keep the motion smooth and natural.)
After that, it was a matter of attaching the arm and calibrating the letters. Each letter is stored internally as a combination of arm and planchette servo positions. I just did this by hand, tweaking positions until I got good alignment for each letter. I could probably have calculated them all based on the distance and angle of the arm and planchette, but I think that would have taken longer than just doing it manually. (To be really cool I'd have set multiple different position pairs for each letter and chosen from them at random to make the motion more natural-feeling, but I didn't have the patience.)
Once that was complete, it was ready for Halloween! I set the board up on a table in my yard and had friends tweet messages to it throughout the night. It was a big hit -- adults were delighted and children were startled :)
I'm a huge Adafruit fanboy, so I subscribe to their quarterly Adabox hardware kits. In one of them (Adabox 008) they included a fun little breakout board called a "Crickit" which makes it easy to control servos, motors, neopixels, even speakers and touch sensors. Lots of fun things!
I wanted to come up with a project to play with some of this, and it was close to Halloween. So naturally, a Halloween decoration would be perfect. After a few thoughtful hours of sitting on my Thinking Couch and drinking some Thinking Beer, an automated Ouija board seemed like a great project to play with this board.
So I drew a few doodles and when I had a rough design ready, I started prototyping. Cardboard and masking tape make fantastic robot prototypes.
It got way easier to deal with once I realized I could also tape the larger "arm" servo to my desk to see something a bit more like real motion:
This was enough to see that the basic idea was solid and that I could probably make this work!