Trackball motion tracking

[JamesBrown]

Originally Posted by slijin

I would use a gyro in conjunction with an accelerometer. I can't say much for trackballs though.

A Gyro/Accelerometer combo will work in the short term but there is drift over time. Higher accuracy/lower drift sensors are available but expensive.

As for the original question it may be beneficial for you wo take apart an old mouse. Typically a trackball mouse includes two encoders that ride along the ball and measure the displacement (X and Z axis), it would be fairly easy to custom build your own devise with sufficient resolution to function at the required speed.