CN102901515A - Rapid on-line measuring method for fiber-optic gyroscope transition time - Google Patents

Abstract

The invention discloses a rapid on-line measuring method for fiber-optic gyroscope transition time. A square signal is adopted to modulate an integrated photoelectric phase modulator, the duty ratio and a peak-to-peak value of the signal are fixed, and a period dereferencing range is a specific numerical value interval. Square signal periods are gradually traversed in the dereferencing range in progressively-increasing sequence, an analog-to-digital converter samples a fiber-optic gyroscope output signal, a digital signal processor modulates a sampled result till the traversal of the square signal periods is finished, and different square signal periods correspond to demodulated results to form sequences. The sequences are subjected to numerical calculation to obtain a minimal value, and the fiber-optic gyroscope transition time can be calculated according to a square signal period corresponding to the minimal value. The rapid on-line measuring method for the fiber-optic gyroscope transition time can achieve quick measurement of the fiber-optic gyroscope transition time on the premise that any testing device or apparatus is not added, solves the problem of transition time change caused by adjustment of an optical system in the production process, and meets the engineering and mass production requirement of a fiber-optic gyroscope.

Description

The On-line rapid measurement method of a kind of optical fibre gyro transit time

Technical field

The present invention relates to the disposal route of signal of fiber optical gyroscope, relate in particular to the On-line rapid measurement method of a kind of optical fibre gyro transit time.

Background technology

Light has all needed time of propagating in the light path of reciprocity optical fibre gyro and is called the transit time.Mostly adopt at present the technological means of digital closed loop both at home and abroad in middle high-precision optical fiber gyro research field, by the integrated electro phase-modulator optical fibre gyro is modulated, analog to digital converter is converted to digital signal with the output analog voltage signal of optical fibre gyro, carries out differential ference spiral by digital signal processor and processes.The integrated electro phase-modulator mainly plays two effects: optical system is carried out the time delay differential modulation, and the operating bias that changes optical fibre gyro puts to improve sensitivity and the linearity; The phase differential that detects is fed back, realize the operation with closed ring of optical fibre gyro.

Zero partially stability is the key index of optical fibre gyro, improves the modulation error that zero partially stable method is to reduce the integrated electro phase-modulator.The introducing of modulation error mainly is because semiperiod of modulation signal and the transit time is unequal, the nonlinear response of the non-linear and integrated electro phase-modulator of modulation channels etc.The semiperiod of modulation signal and transit time are unequal to be topmost factor, the existence meeting of this error is so that optical fibre gyro produces relevant skew, be equivalent to the error component of output signal stack optical fibre gyro, reduce precision and the level of resolution of optical fibre gyro, the zero partially therefore easier impact that is subjected to environmental change of stability.Therefore, know accurately transit time of optical fibre gyro and to choose suitable modulation period with this be to improve zero basic premise of stability partially.

Length and the refractive index of the transit time of optical fibre gyro by the reciprocity light path determines, is different numerical value for different optical systems.In the production run of optical fibre gyro, the refractive index of fiber optic loop can be regarded as constant, and the transit time is mainly just determined by the length of fiber optic loop so.In the production run of fiber optic loop, can obtain according to the length of fiber optic loop the estimated value of transit time, this estimated value precision is about the 50ns magnitude.The precision level of this estimated value obviously can not satisfy the requirement of middle high-precision optical fiber gyro, and in the production run of optical fibre gyro, there is the mutual welding of a plurality of photoelectric devices, therefore the length of fiber optic loop can change again, when all photoelectric devices assemble complete after the reciprocity light path of whole optical fibre gyro just determined.Therefore need a kind of method, can assemble complete other additional devices or the equipment of not utilizing later optical fibre gyro, only rely on the transit time estimated value, method by the signal processing, realize the On-line rapid measurement of optical fibre gyro transit time, when satisfying measuring accuracy, reach the requirement that the optical fibre gyro through engineering approaches is produced.

Summary of the invention

For in the high-precision optical fiber gyro through engineering approaches production run at present to the online Measurement accuracy demand of transit time, solve the problem that causes the transit time variation in the production run because of the optical system adjustment, the object of the present invention is to provide the method for a kind of On-line rapid measurement optical fibre gyro transit time.

The objective of the invention is to be achieved through the following technical solutions: the On-line rapid measurement method of a kind of optical fibre gyro transit time, the step of the method is as follows:

(1) adopt square-wave signal that the integrated electro phase-modulator is modulated, the dutycycle of this signal is fixed, and peak-to-peak value is fixed, and the cycle span is that a special value is interval;

(2) the square-wave signal cycle travels through one by one by the order that increases progressively in span, and analog to digital converter is sampled to Optical Fiber Gyroscope, and digital signal processor carries out demodulation to sampled result;

(3) repeating step 2, until square-wave signal cycle traversal fully, the corresponding demodulation result of the different cycles of gained forms a sequence;

(4) this sequence is carried out numerical evaluation and obtain minimal value, can calculate the transit time of optical fibre gyro according to the corresponding square-wave cycle of minimal value.

Further, in the described step 1, the modulated square wave signal dutyfactor of described integrated electro phase-modulator is 1:1, and peak-to-peak value is fixed as half of integrated electro half-wave voltage of phase modulator; The square-wave signal cycle T _nSpan be designated as T ₀≤ T _n≤ T _N, n=0 wherein, 1,2 ..., N, T _O=2 * (1-10%) τ _Estimate, T _N=2 * (1+10%) τ _Estimate, τ _EstimateBe optical fibre gyro transit time estimated value.

Further, described step 2 is specially: the square-wave signal cycle travels through one by one by the order that increases progressively in span, analog to digital converter is sampled to Optical Fiber Gyroscope, digital signal processor carries out demodulation to sampled result, until square-wave signal cycle traversal is fully, the different cycles T of gained _nCorresponding demodulation result forms a sequence D _n

Further, described step 4 is specially: to described demodulation result sequence D _nCarry out numerical evaluation and obtain minimal value D _Min, its algorithm is D _Min=min[D ₀, D ₁, D ₂... D _N], according to D _MinObtain corresponding square wave signal period T _Min, optical fibre gyro transit time then

The beneficial effect that the present invention has is: the transit time that the present invention can the on-line measurement optical fibre gyro, whole measuring process does not need to add any device or testing apparatus; According to the Measurement Algorithm flow process, whole measuring process only needs about 0.1s, its fast characteristic be enough to satisfy through engineering approaches, the mass production requirement of optical fibre gyro.

Description of drawings

Fig. 1 is the optical fibre gyro system structural representation;

Fig. 2 is T _nOptical Fiber Gyroscope synoptic diagram during=2 τ;

Fig. 3 is T _nOptical Fiber Gyroscope synoptic diagram during 2 τ;

Fig. 4 is T _nOptical Fiber Gyroscope synoptic diagram during＜2 τ;

Fig. 5 is optical fibre gyro output pulse signal width and modulation signal cycle T _nConcern synoptic diagram;

Fig. 6 is the algorithm flow synoptic diagram of measuring optical fiber gyro transit time.

Embodiment

Inventive principle of the present invention is:

Setting the square-wave signal modulation amplitude is

Can be expressed as follows:

${\mathrm{\&phi;}}_m\left(t\right)=\left\{\begin{array}{c}\frac{\mathrm{\&pi;}}{4}...............k{T}_n<t\&le;(k+\frac{1}{2})T_n\\ -\frac{\mathrm{\&pi;}}{4}...............(k+\frac{1}{2})T_n<t\&le;(k+1)T_n\end{array}\right.k\&Element;Z---\left(1\right)$

Wherein, φ _m(t) phase modulation of integrated electro phase-modulator introducing, t is the time, T _nBe the square-wave frequency modulation cycle, k is sequence numbering modulation period.The transit time of supposing optical fibre gyro is τ, according to the time delay differential modulation principle, and the phase difference φ behind the two-beam process integrated electro phase-modulator of the clockwise propagation in edge and the counterclockwise propagation in edge in the light path _m(t) be:

Δφ _m(t)=φ _m(t)-φ _m(t-τ)（2）

The output signal of optical fibre gyro is expressed as:

I(t)=I ₀{1+cos[Δφ _m(t)]}（3）

Wherein, I ₀Be the optical fibre gyro input optical signal, I (t) is optical fibre gyro output interference light intensity signal.

A) work as T _nDuring=2 τ, can obtain in conjunction with (1), (2) formula:

$\mathrm{\&Delta;}{\mathrm{\&phi;}}_m\left(t\right)=\left\{\begin{array}{c}\frac{\mathrm{\&pi;}}{2}...............k{T}_n<t\&le;(k+\frac{1}{2})T_n\\ -\frac{\mathrm{\&pi;}}{2}...............(k+\frac{1}{2})T_n<t\&le;(k+1)T_n\end{array}\right.k\&Element;Z---\left(4\right)$

Can be obtained by (3) formula:

I(t)=I ₀ （5）

Fig. 2 is T _nOptical Fiber Gyroscope synoptic diagram during=2 τ, under square-wave frequency modulation, according to the time delay differential modulation principle, the phase difference φ of two beam reversal's propagates light _m(t) value only has

Two kinds of value condition, the output signal that can be obtained optical fibre gyro by interference of light response expression formula (3) is a constant I ₀

B) work as T _nDuring 2 τ, can obtain in conjunction with (1), (2) formula:

$\mathrm{\&Delta;}{\mathrm{\&phi;}}_m\left(t\right)=\left\{\begin{array}{c}0.........k{T}_n<t\&le;(k+\frac{1}{2})T_n-\mathrm{\&tau;}\\ \frac{\mathrm{\&pi;}}{2}.........(k+\frac{1}{2})T_n-\mathrm{\&tau;}<t\&le;(k+\frac{1}{2}){\mathrm{<figure-callout\; id="0"\; label="T\; n"\; filenames="HDA00002202728100031.png,HDA00002202728100041.png"\; state="\{\{state\}\}">T</figure-callout>}}_n\\ 0.........(k+\frac{1}{2})T_n<t\&le;(k+1)T_n-\mathrm{\&tau;}\\ -\frac{\mathrm{\&pi;}}{2}.........(k+1)T_n-\mathrm{\&tau;}<t\&le;(k+1)T\end{array}\right.k\&Element;Z---\left(6\right)$

Can be obtained by (3) formula:

Fig. 3 is T _nOptical Fiber Gyroscope synoptic diagram during 2 τ, because T _n2 τ, according to the time delay differential modulation principle, the phase difference φ of two beam reversal's propagates light _m(t) value except

Outer also promising 0 situation, the output signal that can be obtained optical fibre gyro by interference of light response expression formula (3) is a constant I ₀The basis on the amplitude that superposeed be 2I ₀Pulse signal, the cycle of pulse signal equals T _n, pulse signal width equals

C) work as T _nDuring＜2 τ, can obtain in conjunction with (1), (2) formula:

$\mathrm{\&Delta;}{\mathrm{\&phi;}}_m\left(t\right)=\left\{\begin{array}{c}0.........k{T}_n<t\&le;(k+1)T_n-\mathrm{\&tau;}\\ \frac{\mathrm{\&pi;}}{2}.........(k+1)T_n-\mathrm{\&tau;}<t\&le;(k+\frac{1}{2}){\mathrm{<figure-callout\; id="0"\; label="T\; n"\; filenames="HDA00002202728100031.png,HDA00002202728100041.png"\; state="\{\{state\}\}">T</figure-callout>}}_n\\ 0.........(k+\frac{1}{2})T_n<t\&le;(k+\frac{3}{2})T_n-\mathrm{\&tau;}\\ -\frac{\mathrm{\&pi;}}{2}.........(k+\frac{3}{2})T_n-\mathrm{\&tau;}<t\&le;(k+1)T\end{array}\right.k\&Element;Z---\left(8\right)$

Can be obtained by (3) formula:

Fig. 4 is T _nOptical Fiber Gyroscope synoptic diagram during＜2 τ is because T _n＜2 τ, according to the time delay differential modulation principle, the phase difference φ of two beam reversal's propagates light _m(t) value except

Outer also promising 0 situation, the output signal that can be obtained optical fibre gyro by interference of light response expression formula (3) is a constant I ₀The basis on the amplitude that superposeed be 2I ₀Pulse signal, the cycle of pulse signal equals T _n, pulse signal width equals

By above-mentioned derivation with as can be known, T _nGet different values near 2 τ, the output interference signal I (t) of optical fibre gyro changes thereupon, works as T _nDuring=2 τ, I (2)=I ₀Be steady state value, work as T _nDuring ≠ 2 τ, I (t) is periodic pulse signal, and peak value of pulse is 2I ₀, the cycle is T _n, pulse width with Perhaps

Value relevant, can be formulated as:

The relation curve in pulse signal width and square-wave frequency modulation cycle as shown in Figure 5.Can obtain square-wave modulation signal cycle and the relation of optical fibre gyro between the transit time according to pulse signal width, T is namely namely arranged when the pulse signal width minimum _n=2 τ.

According to above-mentioned principle, the On-line rapid measurement method of optical fibre gyro transit time of the present invention may further comprise the steps:

1. adopt square-wave signal that the integrated electro phase-modulator is modulated, the dutycycle of this signal is fixed, and peak-to-peak value is fixed, and the cycle span is that a special value is interval.

The modulated square wave signal dutyfactor of integrated electro phase-modulator is 1:1, and peak-to-peak value is fixed as half of integrated electro half-wave voltage of phase modulator; The square-wave signal cycle T _nSpan be designated as T ₀≤ T _n≤ T _N, n=0 wherein, 1,2 ..., N, T ₀=2 * (1-10%) τ _Estimate, T _N=2 * (1+10%) τ _Estimate, τ _EstimateBe optical fibre gyro transit time estimated value, can in the fiber optic loop production run, obtain.

2. the square-wave signal cycle travels through one by one by the order that increases progressively in span, and analog to digital converter is sampled to Optical Fiber Gyroscope, and digital signal processor carries out demodulation to sampled result.

The square-wave signal cycle T _nBy T ₀Increase to gradually T _NProcess in, T _nEvery change one-off pattern number converter is namely once sampled to the output pulse signal of optical fibre gyro, obtains the pulse signal under the current square-wave signal periodic modulation, and then the sampled result of pulse signals is carried out differential ference spiral, obtains demodulation result D _n, D _nProportional relevant with pulse signal width.

3. repeating step 2, until T _n=T _N, the corresponding demodulation result of the different cycles of gained forms a sequence;

At T _nThe change process in, obtain altogether N+1 demodulation result, be expressed as D _n=D ₀, D ₁, D ₂... D _N, these values and cycle T _n(n=0,1,2 ..., N) corresponding one by one.

4. this sequence is carried out numerical evaluation and obtain minimal value, can calculate the transit time of optical fibre gyro according to the corresponding square-wave cycle of minimal value.

To sequence D _nCarry out numerical evaluation and obtain its minimum value D _Min, algorithm is D _Min=min[D ₀, D ₁, D ₂... D _N], with D _MinThe cycle T of corresponding modulation signal _nCan be expressed as T _Min, can know T by derivation before _Min=2 τ, namely the transit time of optical fibre gyro can be by formula

Obtain.

The algorithm flow chart of measuring as shown in Figure 5.System carries out after the initialization calculating according to the estimated value of the transit time of optical fibre gyro the span T in square-wave modulation signal cycle ₀≤ T _n≤ T _N, n=0 wherein, 1,2 ..., N, T ₀=2 * (1-10%) τ _Estimate, T _N=2 * (1+10%) τ _Estimate, τ _EstimateBe optical fibre gyro transit time estimated value, can in the fiber optic loop production run, obtain.The square-wave modulation signal cycle T _nBy T ₀Increase to gradually T _N, T _nEvery change one-off pattern number converter namely carries out one group of sampling to Optical Fiber Gyroscope, and then digital signal processor carries out differential ference spiral, T to sampled result _nAll value circulations are finished and are finally obtained the demodulation result sequence D _n, to the demodulation result sequence D _nCarry out numerical evaluation and obtain minimal value D _Min, according to minimal value D _MinSquare-wave modulation signal cycle T with correspondence _nCount T _Min, the transit time of optical fibre gyro can be passed through formula as can be known according to the derivation of preamble

Calculate.

Claims (4)

1. the On-line rapid measurement method of an optical fibre gyro transit time is characterized in that, the step of the method is as follows:

(1) adopt square-wave signal that the integrated electro phase-modulator is modulated, the dutycycle of this signal is fixed, and peak-to-peak value is fixed, and the cycle span is that a special value is interval;

(2) the square-wave signal cycle travels through one by one by the order that increases progressively in span, and analog to digital converter is sampled to Optical Fiber Gyroscope, and digital signal processor carries out demodulation to sampled result;

(3) repeating step 2, until square-wave signal cycle traversal fully, the corresponding demodulation result of the different cycles of gained forms a sequence;

(4) this sequence is carried out numerical evaluation and obtain minimal value, can calculate the transit time of optical fibre gyro according to the corresponding square-wave cycle of minimal value.

2. the On-line rapid measurement method of optical fibre gyro transit time according to claim 1, it is characterized in that: in the described step 1, the modulated square wave signal dutyfactor of described integrated electro phase-modulator is 1:1, and peak-to-peak value is fixed as half of integrated electro half-wave voltage of phase modulator; The square-wave signal cycle T _nSpan be designated as T ₀≤ T _n≤ T _N, n=0 wherein, 1,2 ..., N, T ₀=2 * (1-10%) τ _Estimate, T _N=2 * (1+10%) τ _Estimate, τ _EstimateBe optical fibre gyro transit time estimated value.

3. the On-line rapid measurement method of optical fibre gyro transit time according to claim 1, it is characterized in that: described step 2 is specially: the square-wave signal cycle travels through one by one by the order that increases progressively in span, analog to digital converter is sampled to Optical Fiber Gyroscope, digital signal processor carries out demodulation to sampled result, until square-wave signal cycle traversal is fully, the different cycles T of gained _nCorresponding demodulation result forms a sequence D _n

4. the On-line rapid measurement method of a kind of optical fibre gyro transit time according to claim 1, it is characterized in that: described step 4 is specially: to described demodulation result sequence D _nCarry out numerical evaluation and obtain minimal value D _Min, its algorithm is D _Min=min[D ₀, D ₁, D ₂... D _N], according to D _MinObtain corresponding square wave signal period T _Min, optical fibre gyro transit time then

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