Closed-loop compensation of the cross-coupling error in a quartz Coriolis Vibrating Gyro

In this paper, the issue related to the quadrature error in a piezoelectric angular rate gyro is studied. Fabrication process and anisoelasticity of the material are known to reduce the performance of the bias stability of micromachined gyros. However, solutions exist to compensate for the quadrature error in silicon-based gyros: DC voltage, parallel capacitance. The principle of operation presented in this paper is based on charge injection in opposite phase to balance the charges induced by the quadrature error in quartz Coriolis Vibrating Gyros. The concept is experimentally tested first with an open-loop circuit. The result of this experiment showed a bias stability of 96°/h RMS over the temperature range. An additional closed-loop feedback circuit is designed and experimented. The active compensation of the quadrature error then improves the bias stability by 5 times, leading to a performance of 20°/h RMS over temperature.

► Quadrature error compensation in quartz Coriolis Vibrating Gyros.
► Passive charge re-injection leads to a bias stability of 96°/h RMS over the temperature range (−25 to +75 °C).
► Active compensation by controlling the charge re-injection from a double phase/quadrature demodulation.
► Active charge re-injection leads to a bias stability of 20°/h RMS over the temperature range (−25 to +75 °C).