Continuously self-calibrating CVG system using hemispherical resonator gyroscopes

This paper reports development and validation over temperature of a drift free Coriolis Vibratory Gyroscope (CVG) system using two 30 mm diameter HRGs mechanized as inner electrode milli-HRG with IRAD CVG electronics. The system employs mode reversal for bias and pattern angle modulation for scale factor self-calibration. Mission software runs on a standard PC and performs sequencing of the self-calibration and fusion of the individual gyro data into a single uninterrupted delta-theta stream. Extensive rate table testing of the system was conducted to characterize performance. Tests demonstrated a 2-3 orders of magnitude improvement of stability over individual gyros in a 30 C temperature range, and a stability of 100 micro-deg/hr without temperature control at a week time scale. These results provide a new level of validation for self-calibrated CVG system approach and its revolutionary potential to overcome the CVG accuracy limitations and enable high performance free inertial applications with unprecedentedly low SWaP and factory calibration cost. Although the work is still ongoing, we have not yet discovered the limits of self-calibration.