Readout method and electronic bandwidth control for a silicon in-plane tuning fork gyroscope

• US 8,677,821 B2
• Filed: 05/19/2011
• Issued: 03/25/2014
• Est. Priority Date: 07/13/2007
• Status: Active Grant

• Current Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Ayazi, Farrokh, Sharma, Ajit, Zaman, Mohammad Faisal
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US13/111,501
• Publication Number:
  US 20120192647A1
• Time in Patent Office: 1,041 Days
• Field of Search: 702/127, 702/189, 702/193, 735/041.2, 735/041.3, 735/041.4, 735/040.2, 735/040.4
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis

Abstract

Disclosed are methods and a sensor architecture that utilizes the residual quadrature error in a gyroscope to achieve and maintain perfect mode-matching, i.e., ˜0 Hz split between the drive and sense mode frequencies, and to electronically control sensor bandwidth. In a reduced-to-practice embodiment, a 6 mW, 3V CMOS ASIC and control algorithm are interfaced to a mode-matched MEMS tuning fork gyroscope to implement an angular rate sensor with bias drift as low as 0.15°/hr and angle random walk of 0.003°/√hr, which is the lowest recorded to date for a silicon MEMS gyroscope. The system bandwidth can be configured between 0.1 Hz and 1 kHz.

Claims

1. A mode matching method for use with a microelectromechanical systems gyroscope, comprising:

determining a current zero rate output level of the gyroscope;

storing the current zero rate output level;

determining if the current zero rate output level is greater than or equal to a previous zero rate output level;

if the current zero rate output level is less than the previous zero rate output level, incrementing a counter, increasing polarization voltage applied to the gyroscope, and determining the zero rate output level of the gyroscope;

if the current zero rate output level is greater than or equal to the previous zero rate output level, decreasing the polarization voltage applied to the gyroscope, and verifying a phase difference (.DELTA. .phi.) between drive and sense signals applied to and derived from the gyroscope;

iteratively incrementing the polarization voltage until a maximum in residual zero rate output amplitude level is detected;

monitoring a 90.degree, phase difference to ensure that mode-matching is achieved; and

once mode matching is achieved, controlling a bandwidth of the gyroscope by varying the polarization voltage to introduce a controlled frequency separation between drive and sense resonant modes of the gyroscope.