MP3: Bubble Chaser (webpage work-in-progress)

Brian B.
Link to Github


For my project, I altered a Fubbles Bump 'n Bubble Robot to follow sound. Out of the box, this toy drives forward blowing bubbles until it bumps something at which point it turns right until its path is clear to move forward again. It uses only one DC motor and lots of gears to power a blower, rotating bubble wand, and wheels on a rotating axel.

My plan was to modify the robot to follow sound instead of wandering aimlessly. To accomplish this, I added two microphone "ears", one on each side. Since the rotation of the front axel was connected to the gears, I simply taped it to keep it from rotating. Then I removed the rear wheels and replaced them with an axel connected to a servo motor, allowing them to turn on command.

Idea Brainstorm

The first two of these I purchased and tried to use for this project.
  • Solar powered butterfly(x2): This is the idea that I initially worked on for awhile before giving up and switching to the current idea. I wanted to build an Alexander Calder style mobile with motors and sensors. The solar panels would be both sensors (which could be shaded by other parts of the mobile) and external power for the DC motors. Users would interact with implicitly by walking past or by explicitly blowing on it (you are not allowed to do this with Calder exhibits I found out). Breaking apart the devices was easy, but building a mobile proved to be too time-consuming.
  • Solar phone charger: My idea was to make a fun, interactive charging station that would be a public works project and promote solar/renewable energy. Studies have shown that a distributed network of solar power sources for cell phone charging could be extremely valuable in the aftermath of natural disaster. As I started working on this device I realized that I mostly wanted to add to it and wouldn't be doing enough "breaking and remaking".
  • Broken joke telling toy: it tells a corny joke when you press a button. Many possibilities.
  • Vibrating panties: This is a sincere idea, but I didn't think it would be accepted or taken seriously in a CS class. The idea is to remake them by adding temperature sensors, calendar functions, etc. to track ovulation and provide haptic feedback for people struggling with fertility issues. You might say that's impractical and/or silly, but I've known people who struggled with infertility and were overwhelmed by "practical" things. It takes an emotional toll and something silly and fun could be refreshing.

Selected Artifact Description and Breakdown


Materials and Parts

A table with estimated costs of your materials and parts and links to the source material at an online store such as,,, etc. The last row should provide the total cost. Please also include the cost of the original product; if you already owned it, list 'FREE.' If you bought it secondhand (e.g., from EBay, Value Village), list the used price. If you bought it new, link to the product online and include its retail price.

Describe the Part's Role In Your Project
Total Cost
Arduino Uno R3
The main brains of our project that interfaces the sensors with our computer and performs some simple onboard signal processing.
Electret Microphone Amplifier - MAX4466 with Adjustable Gain
Used to get audio input from two sides of the toy and detect which direction the sound is coming from.
Servo motor
Used to control turning the rear wheels.
Fubbles Bump 'n Bubble Robot
To be broken and remoken.
Mini skate board
Modified to be rotating rear wheels. The cheapest wheel I could find in the store.

Wiring, resistors, & other basic materials
Used to hook everything up.


Please also include some before and after images that shows off your remade artifact 'before' and 'after.' The example below just shows you what I'm looking for in terms of annotations (it does not show before and after shots).



  • Microphone input was very difficult to work with. I looked at a lot of sample code and read up a lot, but still couldn't get really good readings
  • I used omni-directional microphone which capture sound at a consistent volume regardless of the angle relative to the microphone. This meant that differences in audio levels between the two mics were hard to distinguish from noise. Directional microphones pointed in opposite directions would make the difference more pronounced.
  • Motor noise from the DC motor was a huge hassle. I made the mistake of writing, calibrating, and revising the sensor code before testing the microphone with the motor turned on. Then, the sound of the motor ruined everything.
  • Attaching the motor securely and generally just fastening everything together was difficult.

Future Work Ideas

  • Add some more sophisticated audio filtering to filter out the motor sound. This sound is relatively consistent so it should be possible filter out its frequency.
  • Raise the rear wheels up higher so that they are level with the front wheels.
  • Get more directional microphones to better sense which way to turn.
  • Find some way to make the bubble blower part interactive.

Thoughts about Project

I liked the idea of the project a lot, but it ended up being my least favorite. In the spirit of the project, I felt it was important to use some functionality of the original object rather than just hollowing out a toy and filling it with some electronics. However, I think this attitude made the project feel more limiting than other projects. There was also a time investment in breaking something and understanding how it works before fully planning out the new object to remake it into.

I also found that microphones and audio input were difficult to work with on the Aruduino. I would recommend avoiding them to future students in this class. Most of the other sensors are much easier to use or if audio input is needed, the Kinect is a much easier tool to work with.

Links to Inspirations, Code Libraries, and Code Samples


If you have other references, please list them here in a numbered list.