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This article presents a novel self-calibration method to improve the scale factor (SF) stability by the synchronous control on the first-order and third-order harmonic components of nonlinear detection. On the conventional scheme of a drive loop, the readout amplitude of the first-order harmonic component is controlled at a constant value. However, the actual vibration amplitude of drive-mode motion would drift due to the change of circuit gains between the readout amplitude and actual amplitude, thereby resulting in the deterioration of the SF stability. The third-order harmonic component of nonlinear detection shares the same circuit with the vibration signal, indicating that its readout amplitude can track the change in circuit gains in real time. Therefore, this new approach replaces the original fixed reference with the varying readout amplitude of the third-order harmonic component to eliminate the drive-mode vibration error and eventually calibrate the drift of SF. Experiments performed on a honeycomb disk resonator gyroscope (HDRG) have demonstrated the feasibility of the calibration method. The calibration based on the harmonic extraction yields a short-term SF repeatability of 24.9 ppm and a long-term SF repeatability of 30.8 ppm. Allan deviation analysis of the calibrated SF demonstrates a 3.5-ppm precision upon an average of 200 s. The temperature sensitivity of the SF is reduced from 717.3 ppm/°C to 5.02 ppm/°C and the SF repeatability is improved from 15643 ppm to 94.9 ppm over the temperature range of −30 °C to 30 °C. [ABSTRACT FROM AUTHOR]

Micro hemispherical resonator shows great potential for applications in high-performance gyroscopes. This paper introduces micro hemispherical resonator with teeth-like tines along the edge, aiming at improving mechanical sensitivity of the gyroscope and simplifying the mechanical trimming. The optimized glassblowing resonators with substrate thickness of 200 μm and height near 4.5 mm shows high quality factor, large sensitivity, and balanced electrode gaps. The n = 2 wineglass modes operate at 4.3 kHz, achieving quality factor of 1.18 million and as-fabricated frequency split of 17.8 Hz. After mechanical trimming, the frequency split is reduced below 70 mHz. The vacuum-packaged micro hemispherical resonator gyroscope (mHRG) operating in force-rebalance mode exhibits full-scale range of ±200 deg/sec and bias instability of 0.133 deg/h at room temperature without compensation, indicating that the performance of the gyroscope is limited by the readout electronics. Further improvement is in progress to achieve navigation-grade performance with rate-integrating operation. [ABSTRACT FROM AUTHOR]

Micro glassblowing can be utilized in the fabrication of high-precision micro shell resonator due to its acceptable cost and promising performance. Geometric imperfection characterization and electrode assembly are important but challenging tasks for manufacturing high-quality resonators. This paper characterizes the geometric imperfection of the micro shell resonator and proposes a novel precise assembly process for micro shell resonators with out-of-plane electrodes. The crucial geometric imperfections including thickness imperfection, circularity error and anchor non-planarity of the glassblowing structures are experimentally characterized. The sample resonator exhibits a circularity error below 0.2 % and an anchor non-planarity of 300 nm. The relationship between frequency asymmetry and circularity error is discussed, which can be used to predict the resonator performance. A simplified model is built to analyze the effect of gap deviation on the capacitance variation of the resonator. Finally, a sacrificial layer-free electrode assembly method is proposed, which achieves small ($< 20~\mu \text{m}$) capacitance gaps with relatively low tolerance. [2019-0235] [ABSTRACT FROM AUTHOR]