Patent ID: 7240533
Filing Date: 2007-07-10
Classification: G01C

Abstract:
1. A method for reducing bias error in a Vibrating Structure Gyroscope having a vibrating structure, primary drive means for putting the vibrating structure into carrier mode resonance, primary pick-off means for sensing carrier mode motion, secondary pick-off means for sensing response mode vibration of the vibrating structure in response to applied rotation rate, secondary drive means for applying a force to control the response mode motion, closed loop primary control loops for maintaining a fixed amplitude of motion at the primary pick-off means and for maintaining the drive frequency at the resonance maximum, and secondary control loops for maintaining a null at the secondary pick-off means, in which the ratio SF QUAD divided by SF IN-PHASE is measured from the secondary control loop to provide a direct measurement of Sin (φ SD +φ PPO ), according to the relationship; where SF and phase corrections are applied to one of the secondary drive means and the primary pick-off means to reduce the phase error φ