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A smart foam football that tracks your throws

My team and I cut a Nerf football in half, stuck a WiFi-enabled microcontroller and some accelerometers inside, and wrote some inertial-navigation code to track throw distance and spin rate. This was our final project for Physics 4AL: Mechanics Laboratory.

We started the project by slicing the body of a Nerf Vortex foam football in half with a box-cutter. We chose this particular football because it was cheap, stable during flight (due to the dart-shaped tail) and easy to mount electronics in. The ball had three whistles mounted along its perimeter; we removed one to make room for the electronics.

We had two goals: measure the acceleration of the ball during the throw (which is used to calculated distance thrown) and measure the centripetal acceleration of a point on the ball (which is used to calculate angular velocity).

We needed to use two accelerometers, as it’s impossible to distinguish linear acceleration from centripetal acceleration given a single acceleration vector.”

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