Fundamental frequency estimation from sensor data

Hi there. I'm trying to have an stable fundamental frequency estimator from data coming from a Gforce 2D sensor (I-cube). I'd like to create an installation where the public can control the speed of a video using a conductor's baton. For that reason I need to measure the speed of the movement of the baton. Any suggestions ?. I tried writing the data in a buffer~ and using an fzero~ but the analysis is not accurate. Tried with cpuclock to calculate the elapsed time but was not accurate too...

Thanks

Francisco