MEMS Gyroscope Temperature Performance Optimization Based On Combining Constant Harmonic Ratio And Quadrature Correction

MEMS(Micro-Electro-Mechanical systems)gyroscope is an instrument used to measure the angle or angular rate of moving objects.It has a wide range of applications in the fields of aviation,aerospace,industry and agriculture.Scale factor and zero bias are important parameters for evaluating the performance of the gyroscope.Due to the sensitivity of the gyroscope and its interface circuit to temperature,there is a problem of temperature drift.This limits the performance of MEMS gyroscope.Methods to improve its temperature stability include structural optimization,temperature compensation,and temperature self-calibration.In this paper,a sixteen-sided cobweb-like gyroscope is selected.The effect of temperature on gyroscope performance under the conventional system is analyzed,and improvement schemes are proposed:A new drive closed-loop based on constant harmonic ratio is used to improve the temperature stability of scale factor and a quadrature-coupling stiffness correction loop suppresses the drift of zero bias.Firstly,In view of the temperature-sensitive gyroscope structure and the gain of the interface circuit,the amplitude of the driving modal changes with temperature and the drift of the scale factor.A constant harmonic ratio drive closed-loop system is proposed.Based on the characteristics that the output signal of the parallel-plate capacitor,multiple harmonics exist and the harmonic ratio carries information about the amplitude of mechanical motion,it is used as a control object to design an automatic gain control(AGC)module.Together with the phase-locked loop(PLL)module,a drive closed-loop based on the constant harmonic ratio is formed.This loop improves the stability of the drive mode vibration amplitude and suppresses the temperature drift of the gyroscope scale factor.Then,to solve the problem of zero bias temperature drift caused by the coupling of the quadrature error due to the phase error,a quadrature-coupling stiffness correction loop is designed.The correction voltage is adjusted by closed-loop,cancels the quadrature-coupling stiffness,realizes real-time correction,and lowers the sensitivity of the zero bias to temperature.Finally,experiments are designed.During the temperature change experiment,the temperature range is 5℃ to 65℃.The test result shows that the constant harmonic ratio drive closed-loop reduces the maximum drift of the scale factor from 10.95mV/°/s to 1.24mV/°/s,which is a decrease of 88.9%.After adding the real-time correction closed-loop,the temperature deviation of the zero bias during temperature change is reduced from 0.75°/s to 0.1°/s,which is a decrease of 88.7%;The zero bias instability at room temperature is reduced from 4.05°/h to 0.96°/h,a improvement of 76.3%.The above research work has improved the temperature performance of the gyroscope and laid the foundation for the engineering application of high-precision MEMS gyroscope.