Design of Oscillation Control Loop With Coarse-Precision Mode Transition for Solid-State Resonant Gyroscope

Traditional MEMS gyroscope readout eliminates quadrature error and relies on the phase relationship between the drive displacement and the Coriolis position to accomplish a coherent demodulation. This scheme shows some risk, especially for a mode-matching gyro. If only a slight resonant frequency deviation between the drive and sense mode occurs, a dramatic change in the phase relationship follows, which leads to a wrong demodulation. To solve this, this paper proposes a new readout based on the quadrature error and an auxiliary phase-locked loop (PLL). By tuning the phase shifter in the sense-mode circuit, letting the quadrature error and the carrier of the mixer be in 90° phase alignment, the Coriolis was simultaneously in phase with the carrier. Hence, the demodulation was accomplished. The carrier comes from the PLL output of the drive-mode circuit due to its low jitter and independence of the work mode of the gyro. Moreover, an auxiliary PLL is used to filter the quadrature error to enhance the phase alignment accuracy. Through an elaborate design, a printed circuit board was used to verify the proposed idea. The experimental results show the readout circuit functioned well. The scale factor of the gyro was 6.8 mV/°/s, and the bias instability was 204°/h.

Section: Proposed Readout Circuit Architecturementioning

confidence: 99%

Design of Readout Circuit with Quadrature Error and Auxiliary PLL for MEMS Vibratory Gyroscope

Chen

Zhong

2020

“…An analysis method for the influence of feedback control on the dynamic characteristics of the piezoelectric HRG was developed to hold the standing wave in the initial position by phase feedback determining the angular rate, which demonstrates that the resonator could be balanced by the phase feedback used by the piezoelectric electrodes generating the electrostatic forces [5,20,21,28,29,30]. In force-to-rebalance mode, the measured angular rate is proportional to the voltages applied to the rate control loop.…”

Section: Dynamic Modelmentioning

confidence: 99%

“…It was also found that the capacitance gap distance was a dominant factor for the initial capacitance, and affected the driving voltage and sensitivity [17]. In addition, a reasonable control method was proposed to suppress the effect of coupling between control loops caused by the electrode errors on the HRG [18,19,20,21]. Furthermore, a dynamic model that captures the effects of variation of electrostatic forces, elastic deformation, and residual stress on the mechanical performance was developed to analyze the influence mechanism [22,23,24].…”

Section: Introductionmentioning

confidence: 99%

Effect of Uneven Electrostatic Forces on the Dynamic Characteristics of Capacitive Hemispherical Resonator Gyroscopes

et al. 2019

The hemispherical resonator gyroscope (HRG) is a typical capacitive Coriolis vibratory gyroscope whose performance is inevitably influenced by the uneven electrostatic forces caused by the uneven excitation capacitance gap between the resonator and outer base. First, the mechanism of uneven electrostatic forces due to the significantly uneven capacitance gap in that the non-uniformity of the electrostatic forces can cause irregular deformation of the resonator and further affect the performance and precision of the HRG, was analyzed. According to the analyzed influence mechanism, the dynamic output error model of the HRG was established. In this work, the effect of the first four harmonics of the uneven capacitance gap on the HRG was investigated. It turns out that the zero bias and output error, caused by the first harmonic that dominates mainly the amplitude of the uneven capacitance gap, increase approximately linearly with the increase of the amplitude, and periodically vary with the increase of the phase. The effect of the other three harmonics follows the same law, but their amplitudes are one order of magnitude smaller than that of the first one, thus their effects on the HRG can be neglected. The effect of uneven electrostatic forces caused by the first harmonic on the scale factor is that its nonlinearity increases approximately linearly with the increase of the harmonic amplitude, which was analyzed in depth. Considering comprehensively the zero bias, the modification rate of output error, and scale factor nonlinearity, the tolerance towards the uneven excitation capacitance gap was obtained.

“…The start-up time of gyro driving mode mainly includes frequency locking time [ 11 ] and step response time. At present, most gyro driving mode control systems are using PLL (phase locked loop) to maintain stable operation [ 2 , 12 , 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

A Quick Start Method for MEMS Disk Resonant Gyroscope

Liu

Zhang

2021

High-precision disk resonator gyroscope has a high quality factor in order to improve the performance of the gyroscope, as the high quality factor can lead to a long starting time. In this paper, a control system of the driving loop of the disk MEMS resonant gyroscope with the quick start is designed. The control system has functions of quick frequency locking and fast step response. Coarse-precision mode transition system is designed for quick frequency locking. A large-small mode transition system is designed for fast step response. The correctness of the design is verified by circuit test. The test results show that the start-up time is reduced by over 80% compared with the traditional control loop.