CN102353374A - 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 fibre optic gyroscope signal processing apparatus and method thereof

Technical field

The present invention relates to gyroscope, relate in particular to a kind of fibre optic gyroscope signal processing apparatus 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 got into 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.The Sagnac effect is meant in closed light path; The light that is sent by light source is divided into two bundles; This two-beam gets into 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 CW 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 closed light path rotational angular through measure phase difference.

In practical application; The method of detected phase difference is following: survey the 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 deficiency of prior art, a kind of fibre optic gyroscope signal processing apparatus and method thereof are provided.

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

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

The output current of first photodetector is: $D_4=\frac{2}{9}P{I}_1[1+\mathrm{COS}({\mathrm{\φ}}_S+\frac{2}{3}\mathrm{\π})]---\left(1\right)$

The output current of 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 ₁Be the intensity of light source, φ _SBe the Sagnac phase shift;

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

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

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 three functions of analog to digital conversion.This has improved the integrated level of system greatly, and reliability is improved a lot.

Description of drawings

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

Embodiment

As shown in Figure 1, the fibre optic gyroscope signal processing apparatus comprises light source 1,3 * 3 coupling mechanisms 2, Fibre Optical Sensor ring 3, first photodetector 4, second photodetector 5, electric current/digital conversion integrated circuit 6 and principal computer 7; The light that is sent by light source 1 gets into Fibre Optical Sensor ring 3 through 3 * 3 coupling mechanisms 2; The output signal of Fibre Optical Sensor ring gets into first photodetector 4, electric current/digital conversion integrated circuit 6 and principal computer 7; Simultaneously the output signal of Fibre Optical Sensor ring gets into second photodetector 5, electric current/digital conversion integrated circuit 6 and principal computer 7 and carries out computing, and its output result is proportional to Sagnac phase shift φ under 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 gets into Fibre Optical Sensor rings 3 through 3 * 3 coupling mechanisms 2; The light of Fibre Optical Sensor ring 3 output is converted to electric current output respectively by first photodetector 4, second photodetector 5, the output current of first photodetector 4, second photodetector 5 respectively as follows:

The output current of first photodetector 4 is: $D_4=\frac{2}{9}P{I}_1[1+\mathrm{COS}({\mathrm{\&phi;}}_S+\frac{2}{3}\mathrm{\&pi;})]---\left(1\right)$

The output current of 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 ₁Be the intensity of light source, φ _SBe the Sagnac phase shift;

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

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

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 of carrying out in the principal computer that is digital quantity for ease of understanding, is used D here ₄, D ₅Replace the computing of digital quantity):

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

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

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

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

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

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

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

The expansion of sinx and cosx is following:

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

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

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

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

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

Completion adds, subtract with division after output with 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 accomplish set function, has reduced cost, has improved reliability, and the adjusting of circuit is more prone to.

Claims (2)

1. a fibre optic gyroscope signal processing apparatus is characterized in that comprising light source (1), 3 * 3 coupling mechanisms (2), Fibre Optical Sensor ring (3), first photodetector (4), second photodetector (5), electric current/digital conversion integrated circuit (6) and principal computer (7); The light that is sent by light source (1) gets into Fibre Optical Sensor ring (3) through 3 * 3 coupling mechanisms (2); The output signal of Fibre Optical Sensor ring gets into first photodetector (4), electric current/digital conversion integrated circuit (6) and principal computer (7); The output signal of while Fibre Optical Sensor ring gets into second photodetector (5), electric current/digital conversion integrated circuit (6) and principal computer (7) and carries out computing, and its output result is proportional to Sagnac phase shift

under the little situation of rotating speed.

2. fibre optic gyroscope signal processing method that use is installed according to claim 1; It is characterized in that: after the light that is sent by light source (1) gets into Fibre Optical Sensor rings (3) through 3 * 3 coupling mechanisms (2); The light of Fibre Optical Sensor ring (3) output is converted to electric current output respectively by first photodetector (4), second photodetector (5), and the output current of first photodetector (4), second photodetector (5) is distinguished as follows:

The output current of first photodetector (4) is: (1)

The output current of second photodetector (5) is:

(2)

Wherein P is the responsiveness of photodetector;

is the intensity of light source, and

is the Sagnac phase shift;

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

Wherein

is the output current of photodetector 4;

is the output current of photodetector 5, and

is the Sagnac phase shift.

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