A unique enabling feature of Class

A unique enabling feature of Class II gyroscopes operated in rate measuring (or force rebalance) mode is the ability to arbitrarily place the drive-mode axis, or equivalently the pattern angle, by using proper controls. Detailed theoretical analysis predicts a change in the magnitude and polarity of the gyro bias as a function of drive axis orientation with respect to the fixed geometry of the gyro housing (“pattern angle”). By carouseling the pattern angle around the gyroscope structure,multiple error mechanisms are made observable, including frequency mismatch and misalignment, damping mismatch and misalignment, forcer and pickoff gain mismatch and misalignment, etc. Identification of these error sources through virtual carouseling (or a closely related technique called mode-reversal), enables the gyroscope system to self-calibrate bias and scale factor against device imperfections as well as variations of these imperfections throughout the lifetime of theinstrument