Keeping a ping pong ball bouncing with 4 stepper motors and 4 mics.
The folder CalculatedMoves contains the code for the Arduino which controls the steppers.
The folder MicDiffs contains the code for the Arduino which calculates the ball positions from the noise the ball makes when hitting the plate.
Here's a youtube video of the thing: https://youtu.be/0WiGiJk03Q8