A study on resonant frequency and Q factor tunings for MEMS vibratory gyroscopes

Abstract

A new approach for improving the performance of MEMS vibratory gyroscopes was developed. The methodology suggests a simple way of improving the performance such as the overshoot, settling time and shock immunity by tuning the resonant frequency and the quality factor. The difference in the resonant frequency in two modes (driving and sensing mode) and the quality factors were found to be key factors in determining the dynamics of the gyroscopes. The difference in the frequency could be easily controlled by the electrical stiffness but it was difficult to control the quality factor because it is determined by vacuum level and the shape of structure. An electrostatic feedback technique allowed the control of the quality factor of the micro-gyroscopes. The experimental results show that the magnitude of the resonant peak in the frequency response of the gyroscope is reduced by 58% when the equivalent quality factor of the sensing system is tuned from 264 to 100 at a 100 Hz frequency difference between the driving and sensing modes. The time domain estimation was an approximate 50% reduction in the overshoot and an approximate threefold shortening of the settling time in that case. The estimation in the time domain was based on the simulation because there is no method to measure the transient response of gyroscopes directly.

Stability analysis of a new class of MEMS gyroscopes with parametric resonance

“…Now we go back to our system in Eqs. (5) and (6). First, in the following Section, stability of the linear system (6) is studied and after that, stability of the nonlinear system (5) is examined based on the stability results of the linear system.…”

“…The adjustment is performed using an extra set of comb fingers which electrostatically alter the natural frequencies. The method proposed by Jeong et al [6] is also based on electrostatic tuning of stiffness.…”

Micromachined Vibratory Gyroscopes Controlled by a High-Order Bandpass Sigma-Delta Modulator

“…The parameter that is most affected by fabrication tolerances and changes in environmental conditions is usually the mechanical factor of a vibratory gyroscope [20]. Therefore, it is worth investigating the sensitivity of the proposed control systems to the mechanical quality factor .…”

Performance characterization of a decoupled tri-axis micro angular rate sensor

“…Wide bandwidth for sense mode could make the system to considerably follow a sinusoidal driving command at resonant frequency and exhibit fast response. However, the quality factor has to be accordingly reduced if wide bandwidth is necessarily the higher priority to be considered (Jeong et al 2004). In addition, the performance could be degraded by fabrication imperfections (Painter and Shkel 2002), crossedcoupling effects (Painter and Shkel 2003) and environment variations (Rajendran and Liew 2004) as well.…”