A new control mode greatly improving performance of axisymmetrical vibrating gyroscopes

Coriolis vibrating gyroscopes using axisymmetrical or near-axisymmetrical resonators, such as Sagem Quapason™, hemispherical resonator gyros, cylindrical vibrating gyros, and axisymmetrical MEMS gyros, may work in whole-angle (WA) or in force-to-rebalance (FTR) (angle-rate) mode. Although a specific industrial process is implemented, including defect identification and correction, ageing effects cannot be compensated and affect drift and scale factor stability. This paper shows how the equations governing the relations between defects, commands, and errors can be used to define a new control mode, which combines FTR and WA modes in order to greatly improve performance. The implementation of those principles to the Quapason™ gyro leads to the GVNG gyro (French acronym for Gyro Vibrant Nouvelle Génération — New Generation Vibrating Gyro), a new digitally controlled coriolis vibrating gyroscope. Its experimental results are presented in this paper. The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) for the Clean Sky Joint Technology Initiative under grant agreement no. CSJU-GAM-SFWA-2008-001.