CN102353374B - Fiber-optic gyroscope signal processing device and method thereof - Google Patents

Abstract

The invention discloses a fiber-optic gyroscope signal processing device and a method thereof. The fiber-optic gyroscope signal processing device comprises a light source, a 3 x 3 coupler, a fiber-optic sensing ring, a first photodetector, a second photodetector, a current/digital conversion integrated circuit and a host computer; the light emitted from the light source enters the fiber-optic sensing ring through the 3 * 3 coupler, output signals of the fiber-optic sensing ring enters the first photodetector, the current/digital conversion integrated circuit and the host computer, and simultaneously, the output signals of the fiber-optic sensing ring enters the second photodetector, the current/digital conversion integrated circuit and the host computer to be operated, and the output result is proportional to sagnac phase shift under the condition of a small rotational speed. The fiber-optic gyroscope signal processing device adopts the single-chip current/digital conversion integrated circuit to realize three functions of current/voltage conversion, signal amplification and analog-digital conversion, accordingly, the system integration is greatly improved, and the reliability is greatly improved.

Description

A kind of fiber-optic gyroscope signal processing device and method thereof

Technical field

The present invention relates to gyroscope, relate in particular to a kind of fiber-optic gyroscope signal processing device and method thereof.

Background technology

Fibre optic gyroscope is a kind of device of measuring minor rotation angular velocity or angular displacement, can be divided three classes according to its principle of work: interference type optical fiber gyroscope, resonance type optical fiber gyro and Brillouin scattering formula optical fibre gyro.Wherein ripe with interference type optical fiber gyroscope.In, the interference type optical fiber gyroscope of low precision entered the industrialization stage, be widely used in Aeronautics and Astronautics, submarine and other industrial systems.

The principle of fibre optic gyroscope is Sagnac (sagnac) effect.Sagnac effect refers in closed light path, the light that is sent by light source is divided into two bundles, this two-beam enters fiber optic loop with counter clockwise direction respectively along clockwise direction, and interfere, when this closed light path was not rotated, the phase differential of clockwise direction and anticlockwise two-beam was zero; When closed light path is rotated, just have a phase differential between suitable, the counterclockwise two-beam.Just can obtain the angular velocity that closed light path is rotated by measure phase difference.

In actual applications, the poor method of detected phase is as follows: survey light signal after suitable, counterclockwise two-beam interferes with photodiode, and with the current signal of photodiode output through current/voltage-converted, send into principal computer after amplification and the analog/digital conversion and carry out computing, thereby obtain the value of phase differential.

Summary of the invention

The objective of the invention is to overcome the deficiencies in the prior art, a kind of fiber-optic gyroscope signal processing device and method thereof are provided.

Fiber-optic gyroscope signal processing device comprises light source, 3 * 3 coupling mechanisms, Fibre Optical Sensor ring, the first photodetector, the second photodetector, electric current/digital conversion integrated circuit and principal computer; The light that is sent by light source enters the Fibre Optical Sensor ring through 3 * 3 coupling mechanisms, the output signal of Fibre Optical Sensor ring enters the first photodetector, electric current/digital conversion integrated circuit and principal computer, the output signal of while Fibre Optical Sensor ring enters the second photodetector, electric current/digital conversion integrated circuit and principal computer and carries out computing, and its Output rusults is proportional to Sagnac phase shift φ in the little situation of rotating speed _S

The fibre optic gyroscope signal processing method is: after the light that is sent by light source enters the Fibre Optical Sensor ring by 3 * 3 coupling mechanisms, the light of Fibre Optical Sensor ring output is converted respectively to electric current output by the first photodetector, the second photodetector, and the output current of the first photodetector, the second photodetector is as follows respectively:

The output current of the first photodetector is: ${\mathrm{<figure-callout\; id="4"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_4=\frac{2}{9}P{I}_1[1+\mathrm{COS}({\mathrm{\&phi;}}_S+\frac{2}{3}\mathrm{\&pi;})]---\left(1\right)$

The output current of the second photodetector is: ${\mathrm{<figure-callout\; id="5"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_5=\frac{2}{9}P{I}_1[1+\mathrm{COS}({\mathrm{\&phi;}}_S-\frac{2}{3}\mathrm{\&pi;})]---\left(2\right)$

Wherein P is the responsiveness of photodetector, I ₁The intensity of light source, φ _SBe the Sagnac phase shift;

The change-over circuit of the current signal of the first photodetector in excess current/digital conversion integration module, obtain the set of number amount, the current signal of the second photodetector another change-over circuit in excess current/digital conversion integrated circuit, obtain another group digital quantity, then two groups of digital quantities are sent into principal computer, in the little situation of fibre optic gyroscope rotating speed, carry out computing by following formula:

${\mathrm{\&phi;}}_S\&ap;\frac{1}{-\sqrt{3}}\frac{D_4-D_5}{{\mathrm{<figure-callout\; id="4"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_4+{\mathrm{<figure-callout\; id="5"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_5}$

D wherein ₄Be the output current of photodetector 4, D ₅Be the output current of photodetector 5, φ _SBe the Sagnac phase shift.

The present invention adopts monolithic electric current/digital conversion integrated circuit to realize current/voltage-converted, and signal amplifies and the analog to digital conversion three functions.This has improved the integrated level of system greatly, and reliability is improved a lot.

Description of drawings

Fig. 1 is fibre optic gyroscope signal processing circuit structure synoptic diagram of the present invention.

Embodiment

As shown in Figure 1, fiber-optic gyroscope signal processing device comprises light source 1,3 * 3 coupling mechanisms 2, Fibre Optical Sensor ring 3, the first photodetector 4, the second photodetector 5, electric current/digital conversion integrated circuit 6 and principal computer 7; The light that is sent by light source 1 enters Fibre Optical Sensor ring 3 through 3 * 3 coupling mechanisms 2, the output signal of Fibre Optical Sensor ring enters the first photodetector 4, electric current/digital conversion integrated circuit 6 and principal computer 7, the output signal of while Fibre Optical Sensor ring enters the second photodetector 5, electric current/digital conversion integrated circuit 6 and principal computer 7 and carries out computing, and its Output rusults is proportional to Sagnac phase shift φ in the little situation of rotating speed _S

The fibre optic gyroscope signal processing method is: after the light that is sent by light source 1 enters Fibre Optical Sensor ring 3 by 3 * 3 coupling mechanisms 2, the light of Fibre Optical Sensor ring 3 outputs is converted respectively to electric current output by the first photodetector 4, the second photodetector 5, and the output current of the first photodetector 4, the second photodetector 5 is as follows respectively:

The output current of the first photodetector 4 is: ${\mathrm{<figure-callout\; id="4"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_4=\frac{2}{9}P{I}_1[1+\mathrm{COS}({\mathrm{\&phi;}}_S+\frac{2}{3}\mathrm{\&pi;})]---\left(1\right)$

The output current of the second photodetector 5 is: ${\mathrm{<figure-callout\; id="5"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_5=\frac{2}{9}P{I}_1[1+\mathrm{COS}({\mathrm{\&phi;}}_S-\frac{2}{3}\mathrm{\&pi;})]---\left(2\right)$

Wherein P is the responsiveness of photodetector, I ₁The intensity of light source, φ _SBe the Sagnac phase shift;

The change-over circuit of the current signal of the first photodetector 4 in excess current/digital conversion integration module 6, obtain the set of number amount, the current signal of the second photodetector 5 another change-over circuit in excess current/digital conversion integrated circuit 6, obtain another group digital quantity, then two groups of digital quantities are sent into principal computer 7, in the little situation of fibre optic gyroscope rotating speed, carry out computing by following formula:

${\mathrm{\&phi;}}_S\&ap;\frac{1}{-\sqrt{3}}\frac{D_4-D_5}{{\mathrm{<figure-callout\; id="4"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_4+{\mathrm{<figure-callout\; id="5"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_5}$

D wherein ₄Be the output current of photodetector 4, D ₅Be the output current of photodetector 5, φ _SBe the Sagnac phase shift.

In the present invention, principal computer 7 carries out following computing (because the computing that is digital quantity of carrying out in the principal computer for ease of understanding, is used D herein ₄, D ₅Replace the computing of digital quantity):

$\frac{D_4-D_5}{{\mathrm{<figure-callout\; id="4"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_4+{\mathrm{<figure-callout\; id="5"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_5}$

$\frac{\frac{2}{9}P{I}_1[1+\mathrm{COS}({\mathrm{\&phi;}}_S+\frac{2}{3}\mathrm{\&pi;})]-\frac{2}{9}P{I}_1[1+\mathrm{COS}({\mathrm{\&phi;}}_S-\frac{2}{3}\mathrm{\&pi;})]}{\frac{2}{9}P{I}_1[1+\mathrm{COS}({\mathrm{\&phi;}}_S+\frac{2}{3}\mathrm{\&pi;})]+\frac{2}{9}P{I}_1[1+\mathrm{COS}({\mathrm{\&phi;}}_S-\frac{2}{3}\mathrm{\&pi;})]}$

$=\frac{[1+\mathrm{COS}({\mathrm{\&phi;}}_S+\frac{2}{3}\mathrm{\&pi;})]-[1+\mathrm{COS}({\mathrm{\&phi;}}_S-\frac{2}{3}\mathrm{\&pi;})]}{[1+\mathrm{COS}({\mathrm{\&phi;}}_S+\frac{2}{3}\mathrm{\&pi;})]+[1+\mathrm{COS}({\mathrm{\&phi;}}_S-\frac{2}{3}\mathrm{\&pi;})]}$

$=\frac{-\sin \left({\mathrm{\&phi;}}_S\right)\sin \frac{2}{3}\mathrm{\&pi;}}{1+\cos {\mathrm{\&phi;}}_{\mathrm{<figure-callout\; id="2"\; label="S\; cos"\; filenames="111009134709.png"\; state="\{\{state\}\}">S</figure-callout>}}\cos \frac{2}{3}\mathrm{\&pi;}}$

$=\frac{-\frac{\sqrt{3}}{2}\sin \left({\mathrm{\&phi;}}_S\right)}{1-\frac{1}{2}\cos {\mathrm{\&phi;}}_S}---\left(3\right)$

When rotating speed hour $\frac{-\frac{\sqrt{3}}{2}\sin \left({\mathrm{\&phi;}}_S\right)}{1-\frac{1}{2}\cos \left({\mathrm{\&phi;}}_S\right)}\&ap;-\sqrt{3}{\mathrm{\&phi;}}_S.$ So ${\mathrm{\&phi;}}_S\&ap;\frac{1}{-\sqrt{3}}\frac{D_4-D_5}{{\mathrm{<figure-callout\; id="4"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_4+{\mathrm{<figure-callout\; id="5"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_5}.$

For trying to achieve the approximate value of hour (3) formula of gyroscope speed, need to use the expansion of sinx and cosx.

The expansion of sinx and cosx is as follows:

$\sin x=\underset{n=0}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{{(-1)}^n}{(2n+1)!}{x}^{2n+1},x\&Element;(-\&infin;,+\&infin;)---\left(4\right)$

$\cos x=\underset{n=0}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{{(-1)}^n}{\left(2n\right)!}{x}^{2n},x\&Element;(-\&infin;,+\&infin;)---\left(5\right)$

Getting its front two (3) formulas of bringing into gets:

$\frac{D_4-D_5}{{\mathrm{<figure-callout\; id="4"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_4+{\mathrm{<figure-callout\; id="5"\; label="D"\; filenames="111009134709.png"\; state="\{\{state\}\}">D</figure-callout>}}_5}\&ap;\frac{-\frac{\sqrt{3}}{2}[{\mathrm{\&phi;}}_S-\frac{{\left({\mathrm{\&phi;}}_S\right)}^3}{6}]}{1-\frac{1}{2}[1-\frac{1}{2}{\left({\mathrm{\&phi;}}_S\right)}^2]}---\left(6\right)$

Work as φ _SWhen trending towards zero, following formula is approximately

Finish and add, subtract with division after output and Sagnac phase shift φ _SBe approximated to the signal of direct ratio.

The DDC112 that electric current of the present invention/digital conversion integrated circuit adopts Texas Instruments (TI) in Fig. 1, has only used 7 element circuits just to finish set function, has reduced cost, has improved reliability, and the adjusting of circuit is more prone to.

Claims (1)

1. fibre optic gyroscope signal processing method, it is characterized in that: after the light that is sent by light source (1) enters Fibre Optical Sensor ring (3) by 3 * 3 coupling mechanisms (2), the light of Fibre Optical Sensor ring (3) output is converted respectively to electric current output by the first photodetector (4), the second photodetector (5), and the output current of the first photodetector (4), the second photodetector (5) is as follows respectively:

The output current of the first photodetector (4) is:

(1)

The output current of the second photodetector (5) is:

(2)

Wherein P is the responsiveness of photodetector, The intensity of light source, Be the Sagnac phase shift;

The change-over circuit of the current signal of the first photodetector (4) in excess current/digital conversion integration module (6), obtain the set of number amount, the current signal of the second photodetector (5) another change-over circuit in excess current/digital conversion integrated circuit (6), obtain another group digital quantity, then two groups of digital quantities are sent into principal computer, in the little situation of fibre optic gyroscope rotating speed, carry out computing by following formula:

Wherein

Be the output current of the first photodetector (4),

Be the output current of the second photodetector (5),

Be the Sagnac phase shift.

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