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Micro‐electro‐mechanical system gyroscope detection output is susceptible to drift due to ambient temperature variations. Furthermore, the drive‐mode vibration amplitude is affected by the signal pickup circuit and structural parameters, which significantly influence the temperature drift of the bias and scale factor (SF). This study proposes a vibration amplitude control method based on harmonic amplitude sideband‐ratio (SBR), namely SBR‐AGC, which characterizes the vibration amplitude using the harmonic amplitude ratio of the vibrational electrical signal. The constancy of vibration amplitude is maintained via closed‐loop control to suppress bias and SF temperature drift. The experimental results on cobweb‐like disk resonator gyroscope reveal that the temperature coefficient of bias in the SBR‐AGC mode lies within −20 to 60°C and decreases by 36%, and the temperature coefficient of the SF lies within −10 to 50°C and decreases by 49.7%. Therefore, the environmental adaptability of the gyroscope is effectively improved. [ABSTRACT FROM AUTHOR]

This paper describes a novel rate and rate-integrating mode-switchable axisymmetric gyroscope. A precession angle tracking algorithm is developed to enable the gyro to switch automatically between rate and rate-integrating modes at preset rate points through a digital control system within the gyro. We also propose a vibrating amplitude control method for the rate-integrating mode that directly extracts the angular rate output to ensure switching stability. In rate mode, the bias instability and angle random walk of the gyro reach 0.106°/h and 0.011°/√h, respectively. Additionally, an input range of over ±5000°/s is measured in rate-integrating mode. The scale factor nonlinearity reaches approximately 116 ppm over the full-scale range. The control system implements effective steering control of the gyroscope, with a switching delay of 10 ms from rate mode to rate-integrating mode and 100 ms from rate-integrating to rate mode. The proposed system actualizes a new type of gyroscope with high accuracy and a wide input range, which combines the benefits of rate and rate-integrating modes. [ABSTRACT FROM AUTHOR]

The quadrature coupling error is an important factor that affects the detection output of microelectromechanical system (MEMS) gyroscopes. In this study, two quadrature error control methods, quadrature force-to-rebalance control (Mode I) and quadrature stiffness control (Mode II) were analyzed. We obtained the main factors affecting the zero-rate output (ZRO) under force-to-rebalance (FTR) closed-loop detection. The analysis results showed that the circuit phase delay in Mode I caused the quadrature channel to leak into the in-phase channel. However, in Mode II, the quadrature coupling stiffness was corrected in real time, which effectively improved the stability of the ZRO. The changes in the vibration displacement and Q-factor were the main factors for the ZRO drift in Mode II. Therefore, we propose an online compensation method for ZRO drift based on multiparameter fusion. The experimental results on a cobweb-like disk resonator gyroscope (CDRG) with a 340 k Q-factor showed that the bias instability (BI) of Mode II was significantly better than that of Mode I. After online compensation, the BI reached 0.23°/h, and the bias repeatability reached 3.15°/h at room temperature. [ABSTRACT FROM AUTHOR]

The force-to-rebalance (FTR) closed-loop detection method is commonly used to expand the bandwidth (BW) for micro-electro-mechanical system (MEMS) gyroscopes with low-frequency split and high-quality factors. However, the relationship between the BW and output noise is often incompatible; thus, reducing the detection accuracy of the gyroscope. This paper presents an analysis of the BW and noise spectra under modulation-demodulation FTR gyroscopes. The expressions for the BW and the noise-equivalent rate (NER) spectrum are derived to explore the effects of the loop gain on the BW and NER. It is demonstrated that the gain of the amplifier circuit is maximally transferred to the vibration displacement signal conversion part, which can reduce the output noise without affecting the BW. The simulation and experimental results on the Cobweb-like disk resonator gyroscope show that the derived expressions of BW and NER are correct, and the noise optimization method is effective, which provides an idea for the realization of a high-precision MEMS gyroscope. [ABSTRACT FROM AUTHOR]

A novel cobweb-like disk resonator gyroscope (CDRG) with a very small frequency split between two degenerate modes has been designed and implemented. In comparison with the ring-like DRG (RDRG), the CDRG has fewer fabrication imperfections owing to its all-linear structure. In addition, the CDRG displays a superior nonlinear effect compared with the RDRG, and internal differential electrode excitation and detection were used to further reduce the nonlinear effect. The CDRGs and RDRGs were placed side by side on the same wafer, and the characteristics of these as-fabricated resonators were then tested. The results showed that the resonant frequencies and Q-factors of the CDRGs and RDRGs were approximately 18 kHz and nearly 100k, respectively. The smallest as-fabricated relative frequency split (29.9 ppm) of the CDRGs was about 10.8 times smaller than that (322.5 ppm) of an RDRG built side by side on the same wafer, which had the lowest relative frequency split among all current disk resonator gyros. Finally, the preliminary results for the performance of the CDRG and RDRG in the force-to-rebalance mode and mode matching are given. Under the same conditions, the maximum vibration displacement, scale factor, angular random walk, and bias instability of the CDRG were improved by 62.8%, 112%, 700%, and 314%, respectively, compared with the RDRG. [ABSTRACT FROM AUTHOR]

Frequency symmetry of a cobweb-like disk resonator gyroscope (CDRG) has been compared with a conventional ring-like disk resonant gyroscope (RDRG) in this letter to corroborate that linear beam structures have a better process tolerance than curved beam structures for micro-fabrication processes. The CDRG comprises multiple concentric cobweb-like rings and each is formed by 16 identical straight beams joined end-to-end. It exhibits as-fabricated symmetric vibration behavior superior to RDRGs. To compare as-fabricated structural symmetry, CDRG and RDRG are placed side-by-side on the same wafer and simulated using COMSOL. A tested frequency split as low as 0.56 Hz is achieved for CDRG, and the average relative frequency split is 79.7 ppm, which is approximately seven times smaller than that of RDRG. Additionally, a temperature characteristics test demonstrates that the as-fabricated CDRG has excellent temperature stability, and the relative frequency split varied by 2.83 ppm in the temperature ranging from −20 °C to +80 °C. The proposed concept is verified by the simulation and experimental results. [ABSTRACT FROM AUTHOR]

This paper presents an enhanced stability strategy for the sense mode of a force-rebalanced closed-loop polysilicon micro-hemispherical resonating gyroscope (μHRG) with a high-Q quality-factor value (15.2k). The sense mode closed-loop control including the Coriolis force and quadrature error force rebalanced loop, respectively. Specific demodulation theoretical deductions with mode-split are performed to identify a precise linear model of the sense mode open loop. The frequency responses obtained by experimental tests show good agreement with the theoretical model. The experimental results demonstrate that a bandwidth of 10 Hz and a 0.51 Hz frequency-splitting closed loop gyroscope can be extended to 86 Hz and 3.3 Hz, from 6 Hz and 0.13 Hz in the open loop. The mode-matching (0.51 Hz frequency-splitting) gyroscope with closed loop control can achieve a scale factor of 2.25 mV/°/s with a nonlinearity of 0.087%, and a bias instability of 21.8°/hr with an angle random walk of 3.1°/√hr. [ABSTRACT FROM AUTHOR]

This paper presents a dual quantization lateral-axis capacitive electromechanical sigma–delta modulator (EM- \Sigma \Delta \mathrm M ) vibratory wheel gyroscope under mode-matched condition. A symmetric wheel gyroscope structure was designed, fabricated, and wafer-level packaged under vacuum. The EM- \Sigma \Delta \mathrm M interface loop adopts a fourth-order multifeedback and local resonator \Sigma \Delta \mathrm M noise shaping structure, taking advantage of single-bit and multibit quantization in a single-loop modulator. To evaluate the influence of quantization noise, various numbers of bits of the multibit quantizator were compared and the optimal number of bits was calculated. The interface circuit system was implemented in hardware based on a low-noise front-end application-specified integrated circuit and a back-end discrete-time EM- \Sigma \Delta \mathrm M realized in a field-programmable gate array chip. The system clock was generated using a self-clocking scheme, which allows interfacing to gyroscope with a wide range of drive frequencies. Experimental evaluation indicated that the digital gyroscope system achieved a scale factor of 2073LSB(4.1 mV)/deg/s, with a nonlinearity of 0.046%, a noise floor of 3.1 m°/s/ $\surd $ Hz within a bandwidth of 100 Hz, and a bias instability of 1.3 deg/hr. [2017-0081] [ABSTRACT FROM PUBLISHER]