Final Project - Confessions of a Crazy Cat Lady


For my final project, I wanted to build a cat toy that could engage the cat when I’m not around. I built two versions of the cat toy; the first version used an IR phototransistor to detect motion, and the second used a mic to detect sound.

I made the sound detecting one in the hopes that my cat learns to control the toy by meowing. Forget HCI, I’m doing CCI.

Version 1- IR Phototransistor

Here’s a video of how it works:

The setup consists of an IR phototransistor, a fabduino, and a servo. Here’s the breadboarding stage:

Once I got that working, I ran downstairs to lasercut the body for the toy. When I returned, I mounted everything in the box and... hm. It stopped working.

It turned out that my servo had mysteriously died during the time I was down in the shop. Thankfully, Adam gave me one of his. Thanks Adam!

I discovered a design flaw when I took the toy home for a “user study”. The ambient sensor reading in my apartment is too low! Instead, it became a flashlight controlled toy.

Version 2- Voice Control

The second version uses a mic to detect sounds in the environment. This is the video that solicited the “crazy cat lady” remark from my roommate.

I modified the mic board from Input Week to detect sounds above a certain volume, I then hooked it up to my fabduino-servo setup in place of the IR phototransistor.

(It looks like a mini-PC, doesn’t it?)

One important lesson I learned from this week: heat-shrink is my friend.

I had originally planned to do a cat-voice-detection system that uses a filter bank to group the incoming sound into frequency sub-bands, then compares the result with the spectral fingerprint of the meow sound. I even did some preliminary studies:

User Study

Of course, what kind of cat lady would I be if I don’t show some cat videos? Here’s my cat Leo playing with the IR version of the cat toy.

After the above encounter, Leo actually became scared of the blue ball hanging at the end of the toy. For the sake of getting a good video, I replaced the ball with catnip-scented toy mouse. What you’re about to see next shows the design flaw in my toy construction. The weakest link is indeed...weak.

(Warning: excessive violence, mature audiences only)


My roommate gave me a long look after I showed him the demo video. “You’re the craziest cat lady ever.”