The Coriolis Vibratory Gyroscopes are a type of sensors that measure angular velocities through the Coriolis effect. The resonator is the critical component of the CVGs, the vibrational characteristics of which, including the resonant frequency, frequency mismatch, Q factor, and Q factor asymmetry, have a great influence on the performance of CVG. The frequency mismatch and Q factor of the resonator, in particular, directly determine the precision and drift characteristics of the gyroscope. Although the frequency mismatch and Q factor are natural properties of the resonator, they can change with external conditions, such as temperature, pressure, and external forces. In this paper, the influence of electrostatic forces on the vibrational characteristics of the fused silica cylindrical resonator is investigated. Experiments were performed on a fused silica cylindrical resonator coated with Cr/Au films. It was shown that the resonant frequency, frequency mismatch, and the decay time slightly decreased with electrostatic forces, while the decay time split increased. Lower capacitive gaps and larger applied voltages resulted in lower frequency mismatch and lower decay time. This phenomenon was theoretically analyzed, and the variation trends of results were consistent with the theoretical analysis. This study indicates that, for fused silica cylindrical resonator with electrostatic transduction, the electrostatic influence on the Q factor and frequency, although small, should be considered when designing the capacitive gap and choosing bias voltages.
15 February 2021 in EURASIP Journal on Wireless Communications and Networking
The Hemispherical Resonator Gyroscope (HRG) has many advantages such as high precision, high reliability and long life-time, it is widely used in the space-launcher and the satellites. The HRG has been mechanized to operate in the distinct operating modes, the Force to Rebalanced (FTR) mode and the Whole Angle (WA) mode. In the paper, different from the traditional control algorithm is based on average methods which usually used for the WA mode, a new electrostatic control algorithm is presented, which based on the vector composition and decomposition method to control the equivalent drive force in order to track the phase of the standing wave. The mathematics model and the control algorithm are presented in the paper, and the hardware experimental circuit system is implemented, the HRG has a range of more than 300°/s with the linearity of 40 ppm. Meanwhile, the energy transition efficiency increases by an order of magnitude.
Due to the poor dynamic positioning precision of the Global Positioning System (GPS), Time Series Analysis (TSA) and Kalman filter technology are used to construct the positioning error of GPS. According to the statistical characteristics of the autocorrelation function and partial autocorrelation function of sample data, the Autoregressive (AR) model which is based on a Kalman filter is determined, and the error model of GPS is combined with a Kalman filter to eliminate the random error in GPS dynamic positioning data. The least square method is used for model parameter estimation and adaptability tests, and the experimental results show that the absolute value of the maximum error of longitude and latitude, the mean square error of longitude and latitude and average absolute error of longitude and latitude are all reduced, and the dynamic positioning precision after correction has been significantly improved.
The life and damage of hemispherical resonator are important factors that directly affect the service time and safety of high‐precision hemispherical resonator gyro. However, the fused silica glass material used in the hemispherical resonator which was processed in China is mainly imported, and it is too expensive to use the traditional fatigue life experiment, so it is necessary to use the software of fatigue life analysis to analyze its fatigue life. In the paper, the ANSYS software is used to analyze the fatigue life of fused silica hemispherical resonator, to determine the dangerous parts caused by the residual stress to analyze the crack propagation in the fatigue parts, and to obtain the sum stress intensity factor, so as to effectively monitor and prevent the fatigue‐prone parts in the process of structural design and use of the hemispherical resonator.
The measurement of resonator’s frequency splitting is a critical issue in vibratory gyroscopes, which would be elaborately treated in practical applications. The high‐precision measurement of frequency splitting plays a significant role in frequency tuning control. A novel time‐domain method of frequency splitting measurement for hemispherical resonator based on the standing wave swing effect was proposed. The frequency splitting value of the resonator can be directly obtained by taking the reciprocal of the one cycle time of standing wave swings, rather than through the frequency difference between two resonant modes. To begin with, the method was analyzed theoretically, and the measurement resolution and accuracy of the method were researched in detail. Simulation and experimental results showed that the frequency splitting value can be effectively obtained by measuring the period of the standing wave swings, improving the fine measurement resolution and high accuracy. The frequency splitting of lower than 0.007 Hz has to be effectively obtained in the experiment. It is found that the measurement error is a small proportional part of frequency splitting value, so the measurement accuracy is very high when the frequency splitting is very low. Therefore, this time‐domain method would contribute to the measurement of ultralow‐frequency splitting for high‐Q resonators.
21 May 2022 in Journal of Shanghai Jiaotong University (Science)