Circuit arrangement and method for the digital correction of modulation effects in electromechanical delta-sigma modulators

Patent metadata

Field	Value
Publication number	US-11268828-B2
Application number	US-202016875712-A
Country	US
Kind code	B2
Filing date	May 15, 2020
Priority date	Oct 8, 2015
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

The present invention relates to a circuit arrangement and a method for reading a capacitive vibratory gyroscope with an at least primary mass and at least one secondary mass that is connected to the primary mass, wherein the primary mass is excited to a primary vibration during operation, and wherein the secondary mass is deflected out of a resting position in a direction that is transversal to the primary vibration when the vibratory gyro-scope rotates around a sensitive axis. The circuit arrangement comprises a delta-sigma modulator with at least one control loop to perform a force feedback that resets the secondary mass into its resting state by applying a reset signal, wherein the reset signal forms a modulator output signal of the delta-sigma modulator, a correction unit that receives the modulator output signal and that is operated to generate a corrected modulator output signal that corresponds to an actually acting feedback force, a demodulator that is connected to the correction unit for demodulation of the corrected modulator output signal, and a filter arrangement to filter the demodulated signals and to output a rotary rate signal.

First claim

What is claimed:

1. A method for operating and reading out a capacitive vibratory gyroscope with at least one primary mass and at least one secondary mass that is connected to the primary mass, wherein the method comprises the steps of:
exciting a primary vibration of the primary mass in a first closed control loop;
applying a reset force to the secondary mass in order to counteract a deflection of the secondary mass in a direction that is transverse to the primary vibration out of a resting position when the vibratory gyroscope rotates around a sensitive axis, wherein the reset force is generated in a second closed control loop; and
tapping a feedback signal of the second closed control loop for generating a rotary rate signal, wherein the feedback signal is corrected digitally in order to reproduce a reset force that actually impacts on the secondary mass, the digital correction is performed by multiplication of the feedback signal with a calculated weighting factor.

2. The method according to claim 1 , wherein the weighting factor contains a current position of the primary mass.

3. The method according to claim 1 , wherein a demodulation step and a filtering step are performed after the digital correction.

4. The method according to claim 3 , wherein a low-pass filtering and a decimation filtering process are performed in the filtering step.

5. The method according to claim 1 , wherein the secondary resonance frequency is controlled further by means of a frequency control and wherein the feedback signal is multiplied with a scaled output value of the frequency control in the digital correction step.

6. The method according to claim 1 , wherein the correction is performed for each of a plurality of sample values of the feedback signal.

7. A method for operating and reading out a capacitive vibratory gyroscope with at least one primary mass and at least one secondary mass that is connected to the primary mass, wherein the method comprises the steps of:
exciting a primary vibration of the primary mass in a first closed control loop;
applying a reset force to the secondary mass in order to counteract a deflection of the secondary mass in a direction that is transverse to the primary vibration out of a resting position when the vibratory gyroscope rotates around a sensitive axis, wherein the reset force is generated in a second closed control loop; and
tapping a feedback signal of the second closed control loop for generating a rotary rate signal, wherein the feedback signal is corrected digitally in order to reproduce a reset force that actually impacts on the secondary mass, the secondary resonance frequency is controlled further by means of a frequency control and the feedback signal is multiplied with a scaled output value of the frequency control in the digital correction step.

Assignees

• Univ Freiburg Albert Ludwigs

Inventors

• Maurer Michael
• Manoli Yiannos

Classifications

• G01C19/5726 Primary

  Signal processing · CPC title

• G01C19/5776

  Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719 · CPC title

• G01C19/5712

  the devices involving a micromechanical structure · CPC title

• G01C25/005 Primary

  initial alignment, calibration or starting-up of inertial devices · CPC title