Beat frequency motor position detection scheme for tuning fork gyroscope and other sensors

摘要

A tuning fork gyroscope has an in-plane position sensitive pick-off to which an AC or AC+DC bias is applied. Intermodulation is exploited to produce beat-notes between the applied frequency and the motor frequency at amplitudes proportional to motor amplitude, but unaffected by error sources such as spurious substrate charge accumulation. The beat-notes are used to control motor amplitude without the effects of charge accumulation.