The GYTRIX Quartz Crystal Axisymmetric Mems GYRO: Preliminary measurements

On one hand tuning fork type open-loop quartz crystal MEMS gyroscopes achieve tactical - near navigation -grade performances through the excellent temperature and aging stability of quartz resonators, and the linear piezoelectric transduction. On the other hand, recent developments enable silicon based axisymmetric designs to achieve the same thermo-mechanical behavior of the two gyro modes, improving the bias and scale factor stabilities. They also enable matching the two frequencies and then increasing the scale factor in a force rebalance configuration. The axisymmetric quartz crystal MEMS gyro presented here benefits from the advantages of these two kinds of gyro. Its principle of operation as well as a first design and expected performances were reported; the performance objective of this new cell is to achieve a bias repeatability better than 0.1°/h and an ARW < 0.005°/√hr in the closed loop configuration, as well as good immunity to vibrations and thermal variations. The eigen frequency and Q factor variation identity of the two gyro modes are key parameters enabling bias and scale factor stability, this paper reports the experimental validation of the thermomechanical behavior identity between the drive and sense modes of this new axisymmetric quartz crystal gyro. This is the first step towards a high performance quartz crystal closed-loop gyroscope.