Angle random walk minimization for frequency modulated gyroscopes

Patent metadata

Field	Value
Publication number	US-11268810-B2
Application number	US-201916507453-A
Country	US
Kind code	B2
Filing date	Jul 10, 2019
Priority date	Jul 10, 2019
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

Compared to amplitude modulated gyroscopes, frequency modulated (FM) gyroscopes have demonstrated excellent long-term stability. A notable limitation with FM gyroscopes is FM operation can decrease short-term stability. Short-term stability is typically quantified via angle random walk (ARW). The present disclosure provides an FM gyroscope ARW minimization method.

First claim

What is claimed as new and desired to be protected by Letters Patent of the United States is:

1. A method of determining a driving signal for a dual mode resonator of a gyroscope, said method comprising:
driving, via a first mode phase-locked loop (PLL) set at first mode phase, a first mode of the dual mode resonator;
obtaining, via a detector, a first mode power spectral density (PSD) value of the dual mode resonator, a first mode amplitude of the dual mode resonator and a first mode frequency of the dual mode resonator based on the PLL set at the first mode phase;
repeating said driving the first mode of the dual mode resonator and said obtaining a respective first mode PSD value, a respective first mode amplitude of the dual mode resonator and a respective first mode frequency of the dual mode resonator based on the PLL set at a respective first mode phase a number n times to obtain n respective first mode PSD values of the dual mode resonator, n respective first mode amplitudes of the dual mode resonator and n respective first mode frequencies of the dual mode resonator, each repetition of said driving the first mode of the dual mode resonator and said obtaining a respective first mode PSD value, a respective first mode amplitude of the dual mode resonator and a respective first mode frequency of the dual mode resonator having the first mode PLL being set at a different respective first mode phase;
driving, via a second mode PLL set at second mode phase, a second mode of the dual mode resonator;
obtaining, via the detector, a second mode PSD value of the dual mode resonator, a second mode amplitude of the dual mode resonator and a second mode frequency of the dual mode resonator based on the PLL set at the second mode phase;
repeating said driving the second mode of the dual mode resonator and said obtaining a respective second mode PSD value, a respective second mode amplitude of the dual mode resonator and a respective second mode frequency of the dual mode resonator based on the PLL set at a respective second mode phase a number m times to obtain m respective second mode PSD values of the dual mode resonator, m respective second mode amplitudes of the dual mode resonator and m respective second mode frequencies of the dual mode resonator, each repetition of said driving the second mode of the dual mode resonator and said obtaining a respective second mode PSD value, a respective second mode amplitude of the dual mode resonator and a respective second mode frequency of the dual mode resonator having the second mode PLL being set at a different respective second mode phase;
determining an angle random walk, ARW, value of the dual mode resonator using the following equation,

ARW
⁡

(

deg
/
sec

Hz

)

=

360
⁢

P
1

⁡

(

Δ
⁢

⁢
f

)

⁢

f
s

2

+

P
2

⁡

(

Δ
⁢

⁢
f

)

⁢

f
s

2

1
2

⁢

A
g

⁡

(

a
1

a
2

+

a
2

α
1

)

,

wherein f s is a sampling frequency,
wherein A g is the angular gain of the dual mode resonator,
wherein a 1 is the first mode amplitude of the dual mode resonator based on the PLL set at the first mode phase,
wherein a 2 is the second mode amplitude of the dual mode resonator based on the PLL set at the second mode phase,
wherein f 1 is the first mode frequency of the dual mode resonator based on the PLL set at the first mode phase,
wherein f 2 is the second mode frequency of the dual mode resonator based on the PLL set at the second mode phase,
wherein Δf=|f 1 −f 2 |,
wherein P 1 (Δf) is a PSD value of the first mode frequency of the dual mode resonator based on the PLL set at the first mode phase as demodulated at Δf, and
wherein P 2 (Δf) is a PSD value of the second mode frequency of the dual mode resonator based on the PLL set at the second mode phase as demodulated at Δf.

2. The method of claim 1 , wherein n=m.

3. The method of claim 2 , wherein the PLL is set at the respective first mode phase the number n times between 0° and −180°.

4. The method of claim 3 , wherein the PLL is set at the respe

Assignees

• Government Of The United States As Represented By The Secretary Of The Navy
• Us Navy

Inventors

• Sabater Andrew B

Classifications

• G01C19/574

  the devices having two sensing masses in anti-phase motion · CPC title

• H03L7/08

  Details of the phase-locked loop · CPC title

• G01C19/5712

  the devices involving a micromechanical structure · CPC title

• G01C19/5726 Primary

  Signal processing · CPC title

• G01C19/5776 Primary

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