CN101408426B - Method for enlarging optical fiber gyroscope range - Google Patents

Abstract

The invention relates to a method for increasing the measuring range of an optical fibre gyro. The method comprises: the design of a double sensing ring light path, the double demodulation of a double sensing ring, increasing the spanning stripe measuring range, stripe recognition and speed correction. Based on the spanning stripe treatment, Sagnac with larger measuring range is used for judging interferometric fringe level of the work of the optical fibre gyro formed by Sagnac main sensing rings according to the output angular speed of the sensing rings, and the output angular speed of the Sagnac main sensing rings is corrected, thus increasing the measuring range of the optical fibre gyro, solving the problem that the optical fibre gyro can not be started by electricity in the condition of fast spinning and expanding the application field of the optical fibre gyro; especially, the application of the high precision optical fibre gyro has important significance.

Description

A kind of method that increases optical fiber gyroscope range

Technical field

The present invention relates to a kind of method that increases optical fiber gyroscope range, be specially adapted to the optical fibre gyro of electrifying startup under the high speed rotating situation.

Background technology

Deepening continuously and expanding along with what optical fibre gyro was used, some fields are urgent day by day to the demand of high precision, wide range optical fibre gyro, and having the mutual restriction relation between range index of optical fibre gyro and the precision index, this causes optical fibre gyro to be subjected to obstruction in the application aspect high precision, the wide range.

In order not sacrifice the precision property of optical fibre gyro, and can improve its range, can adopt the method for striding striped to increase the range of optical fibre gyro.Though stride the range that the striped method can increase optical fibre gyro, the problem that can not solve optical fibre gyro electrifying startup under the fast rotational situation is used.Because in this case, optical fibre gyro can't be offered an explanation and oneself is operated on which rank of striped, thus the angle rate signal of possibility output error.So, must make optical fibre gyro under the fast rotational situation, during electrifying startup, can tell residing striped rank.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, provide a kind of and can make optical fibre gyro method of the increase optical fiber gyroscope range of operate as normal during electrifying startup under the fast rotational situation.

Technical solution of the present invention is: increase the method for optical fiber gyroscope range, it is characterized in that realizing by following steps:

(1) design of the two sensing ring light paths of optical fibre gyro

The two sensing ring light paths of optical fibre gyro comprise light source, detector, single-mode optical-fibre coupler, integrated optical modulator, polarization-maintaining fiber coupler and fiber optic loop, polarization-maintaining fiber coupler is between integrated optical modulator and fiber optic loop, the C1 of polarization-maintaining fiber coupler, C3 end tail optical fiber is connected with Y2, the Y3 end tail optical fiber of integrated optical modulator respectively, the C2 of polarization-maintaining fiber coupler, C4 end tail optical fiber is connected with two tail optical fibers of fiber optic loop respectively, Y2, C1, C4, fiber optic loop, C2, C3 and Y3 constitute Sagnac master's sensing ring, and Y2, C1, C3 and Y3 constitute Sagnac from sensing ring;

(2) adopt digital oblique wave closed-loop policy that the signal of Sagnac master's sensing ring is carried out demodulation and obtain angular speed Ω _M

(3) adopt the digital open loop method that Sagnac is carried out demodulation from the signal of sensing ring and obtain angular speed Ω _S

(4) adopt the range of striding striped method increase Sagnac master sensing ring;

(5) the angular speed Ω that utilizes Sagnac to obtain from the sensing ring demodulation _SThe angular speed Ω that demodulation obtains to Sagnac master's sensing ring _MCarrying out the striped rank judges and rate correction.

The striped rank judgement of described step (5) and the step of rate correction:

(1) demarcates optical fibre gyro, obtain the maximum angular speed ± Ω of Sagnac master's sensing ring striped correspondences at different levels _π, ± Ω _{2 π}, ± Ω _{3 π}With ± Ω _{4 π}

(2) when the optical fibre gyro energising started, the demodulation of Sagnac master's sensing ring obtained angular speed Ω _M, Sagnac obtains angular speed Ω from the sensing ring demodulation _S

(3) relatively Sagnac obtains angular speed Ω from the sensing ring demodulation _SWith the maximum angular speed of striped correspondences at different levels, judge the striped rank that Sagnac master's sensing ring is in;

(4) utilize the angular speed Ω of the maximum angular speed of place striped correspondence to Sagnac master's sensing ring _MRevise, promptly obtain the angular speed Ω of the final output of optical fibre gyro _O

Described striped rank is judged and the standard of rate correction is:

When | Ω _S|≤Ω _πThe time, Ω _O=Ω _M

Work as Ω _π≤ Ω _S≤ Ω _{2 π}The time, Ω _O=Ω _M+ Ω _{2 π}

When-Ω _{2 π}≤ Ω _S≤-Ω _πThe time, Ω _O=Ω _M-Ω _{2 π}

Work as Ω _{2 π}≤ Ω _S≤ Ω _{3 π}The time, Ω _O=Ω _M+ Ω _{3 π}

When-Ω _{3 π}≤ Ω _S≤-Ω _{2 π}The time, Ω _O=Ω _M-Ω _{3 π}

Work as Ω _{3 π}≤ Ω _S≤ Ω _{4 π}The time, Ω _O=Ω _M+ Ω _{4 π}

When-Ω _{4 π}≤ Ω _S≤-Ω _{3 π}The time, Ω _O=Ω _M-Ω _{4 π}

The loss of each welding point of described polarization-maintaining coupler tail optical fiber and integrated optical modulator tail optical fiber and fiber optic loop tail optical fiber is less than 0.1dB, and cross-talk is less than-30dB.

The length of described Sagnac master's sensing ring is 300～3000m.

Described Sagnac is 20～30m from the length of sensing ring, angular speed that can responsive 1～2000 °/s.

Described Sagnac master's sensing ring and Sagnac adopt two-way A/D conversion to gather the signal of response from sensing ring, and Sagnac directly carries out the A/D conversion from the not filtering of signal of sensing ring, and the signal of Sagnac master's sensing ring carries out carrying out the A/D conversion behind the bandpass filtering.

Sagnac master's sensing ring of the digital oblique wave closed-loop policy of described employing, the Sagnac that adopts the digital open loop method can be finished by a cover signal processing circuit from signal Processing such as the modulation of the two paths of signals of sensing ring and angular speed corrections.

Described signal processing circuit comprises bandpass filter, A/D, D/A, signal amplifier and FPGA.

The present invention compared with prior art beneficial effect is:

(1) the present invention adopts two sensing ring designs, utilize the big Sagnac of range to judge optical fibre gyro that Sagnac master's sensing ring the constitutes residing interference fringe rank of working from the output angle speed of sensing ring, and the output angle speed of Sagnac master's sensing ring revised, solved the problem that optical fibre gyro can not be switched on and be started under the fast rotational situation.

(2) the present invention has increased the range of optical fibre gyro, has expanded the application of optical fibre gyro, and is especially significant to the application of high-precision optical fiber gyro.

(3) the present invention improves the dynamic perfromance of optical fibre gyro, has improved the performance of inertial navigation system.

(4) the present invention can not influence environmental suitability and the volume of optical fibre gyro, and weight of optical fibre gyro and cost are slightly raise.

Description of drawings

Fig. 1 is the optical fibre gyro light channel structure synoptic diagram of the two sensing rings of the present invention;

Fig. 2 is a signal processing circuit structure synoptic diagram of the present invention.

Embodiment

1, makes the two sensing ring light paths of optical fibre gyro

As shown in Figure 1, the two sensing ring light paths of optical fibre gyro comprise light source 11, detector 12, single-mode optical-fibre coupler 13, integrated optical modulator 14, polarization-maintaining fiber coupler 15 and fiber optic loop 16, polarization-maintaining fiber coupler 15 is between integrated optical modulator 14 and fiber optic loop 16, the C1 of polarization-maintaining fiber coupler 15, C3 end tail optical fiber respectively with the Y2 of integrated optical modulator 14, Y3 end tail optical fiber is connected, the C2 of polarization-maintaining fiber coupler 15, C4 end tail optical fiber is connected with two tail optical fibers of fiber optic loop 16 respectively, Y2, C1, C4, fiber optic loop, C2, C3 and Y3 constitute Sagnac master's sensing ring, Y2, C1, C3 and Y3 tail optical fiber constitute Sagnac from sensing ring.

The loss of each welding point of polarization-maintaining coupler 15 tail optical fibers and integrated optical modulator 14 tail optical fibers, fiber optic loop 16 tail optical fibers should be less than 0.1dB, and cross-talk should be less than-30dB.

The relation of the Sagnac phase differential that optical fibre gyro output angle speed and input angle speed cause can be expressed as:

Wherein, Ω is that output angle speed, λ are that wavelength of optical signal, c are that the light velocity, L are that fiber optic coils length, D are the fiber optic coils effective diameter,

The phase differential that causes for input angle speed.Optical fibre gyro exist one with zero be the center ± the dull phase measurement scope of π rad, corresponding angular speed also have one ± Ω _πMonodrome measurement range, i.e. range:

${\mathrm{\&Omega;}}_{\mathrm{\&pi;}}=\frac{\mathrm{\&lambda;<figure-callout\; id="2"\; label="c"\; filenames="H2008102267469E00012.png"\; state="\{\{state\}\}">c</figure-callout>}}{2\mathrm{LD}}---\left(2\right)$

The following formula explanation, the range of optical fibre gyro depends on the wavelength of the length of fiber optic coils, effective diameter and light signal.

As shown in Figure 1, the length of the length of Sagnac master's sensing ring much larger than Sagnac from sensing ring, but the effective diameter of the two is equal substantially.By formula (2) as can be known, the former range is far smaller than the latter's range.

The length of Sagnac master's sensing ring is generally 300～3000m, and the Sagnac sensing ring of its function and ordinary optic fibre gyro is identical, is the sensing unit of optical fibre gyro measured angular speed, and the precision of optical fibre gyro is played a decisive role.Sagnac is generally 20～30m from the length of sensing ring, and angular speed that can responsive 1～2000 °/s works under bigger angular speed input, to the residing work striped of optical fibre gyro with judge.

2, Sagnac master's sensing ring and Sagnac are carried out the bilingual accent of closed loop and open loop respectively from sensing ring

Digital oblique wave closed-loop fashion is adopted in the signal demodulation of Sagnac master's sensing ring, and demodulation obtains angular speed Ω _M, identical with the demodulation mode of common closed-loop fiber optic gyroscope, Sagnac adopts the digital open loop mode from the signal demodulation of sensing ring, and demodulation obtains angular speed Ω _S, the modulation of two paths of signals can be finished by a cover signal processing circuit.

As shown in Figure 2, signal processing circuit comprises bandpass filter 21, an A/D23, the 2nd A/D22, D/A25, signal amplifier 26 and FPGA24.Because the signal of Sagnac master's sensing ring is the foundation of the output signal of optical fibre gyro, so need to adopt digital oblique wave closed loop demodulation scheme, to realize higher precision, the demodulation mode of this closed loop demodulation scheme and common closed-loop fiber optic gyroscope is identical.In order to increase the range of optical fibre gyro, the signal of Sagnac master's sensing ring also will adopt strides the striped processing.Sagnac is used to judge and the work striped rank of main signal just is used for detecting bigger angular speed that required precision is very low, so adopt the digital open loop demodulation scheme from the signal of sensing ring.

The signal Processing design needs to consider to eliminate or suppress crosstalking between open loop, the closed loop two-way restituted signal.Consider that Sagnac is from the eigenfrequency of the sensing ring high order of magnitude than Sagnac master's sensing ring, gather the signal of two Sagnac sensing ring responses respectively so adopt two-way A/D conversion, to the signal not filtering of Sagnac from sensing ring, directly carry out the A/D conversion, the signal of Sagnac master's sensing ring is carried out carrying out the A/D conversion behind the bandpass filtering, to weaken Sagnac from the interference of the high-frequency signal of sensing ring to its generation.

3, stride the range that the striped method increases Sagnac master's sensing ring

The demodulation of Sagnac master's sensing ring signal is adopted on the basis of digital oblique wave closed loop policy and is striden striped method increase range.Phase place step amplitude in the phase register that is stored in the demodulation of digital oblique wave closed loop is adjusted, made its phase place, promptly realize striding striped greater than ± π.Optical fibre gyro is finished modulation usually on first order interference fringe, detectable maximal phase potential difference is ± π that corresponding maximum angular speed is ± Ω _πStriding this method of striped allows optical fibre gyro to finish modulation on second level striped or even more senior striped.If be cross over second level striped, but then corresponding detected phase difference is 2 π, and corresponding maximum angular speed is ± Ω _{2 π}, the range of optical fibre gyro just increases 2 times for not striding striped; The rest may be inferred, and the fringe order of striding is many more, and then range is big more.

Striding striped can make the minimum angle increment of optical fibre gyro become big.In some applications, especially the application of stablizing and locating needs optical fibre gyro that less angle increment is arranged.Therefore, in actual applications, stride the striped method, be no more than fourth stage striped usually as employing.

4, the correction of other identification of fringe order and speed

Sagnac master's sensing ring and Sagnac are after all demodulation is come out from the signal of sensing ring, size by the comparative analysis two paths of signals, the signal that can judge Sagnac master's sensing ring is operated in first order striped, or the second level or third level striped, after judged result draws, rank according to striped is revised the angular speed of Sagnac master's sensing ring response, and then exports as the output angle speed of optical fibre gyro.Sagnac measures big angular speed from sensing ring, can adopt open loop policy, utilizes it to judge optical fibre gyro residing striped rank of working, and revises the output speed of optical fibre gyro.

The angular speed Ω that utilizes Sagnac to obtain from the sensing ring demodulation _SThe angular speed Ω that demodulation obtains to Sagnac master's sensing ring _MCarry out the striped rank and judge and rate correction, can guarantee that optical fibre gyro keeps normal angular speed output when switching in rotation.

The specific practice of striped recognition methods is:

At first optical fibre gyro is demarcated, obtain the maximum angular speed ± Ω of main sensing ring striped correspondences at different levels respectively _π, ± Ω _{2 π}, ± Ω _{3 π}With ± Ω _{4 π}When optical fibre gyro was switched on, the demodulation of Sagnac master's sensing ring closed loop obtained angular speed Ω _M, Sagnac obtains angular speed Ω from sensing ring open loop demodulation _S, the angular speed Ω of the final output of optical fibre gyro _OFor:

When | Ω _S|≤Ω _π, the time, Ω _O=Ω _M

Work as Ω _π≤ Ω _S≤ Ω _{2 π}The time, Ω _O=Ω _M+ Ω _{2 π}

When-Ω _{2 π}≤ Ω _S≤-Ω _πThe time, Ω _O=Ω _M-Ω _{2 π}

Work as Ω _{2 π}≤ Ω _S≤ Ω _{3 π}The time, Ω _O=Ω _M+ Ω _{3 π}

When-Ω _{3 π}≤ Ω _S≤-Ω _{2 π}The time, Ω _O=Ω _M-Ω _{3 π}

Work as Ω _{3 π}≤ Ω _S≤ Ω _{4 π}The time, Ω _O=Ω _M+ Ω _{4 π}

When-Ω _{4 π}≤ Ω _S≤-Ω _{3 π}The time, Ω _O=Ω _M-Ω _{4 π}

The course of work of the present invention: low polarized light source 11 sends flashlight under the control of control circuit for light source, enter integrated optical modulator 14 through behind the single-mode optical-fibre coupler 13, light signal is risen partially in integrated optical modulator 14, modulation, become the line polarisation, and be divided into two-way, export from the two ends tail optical fiber coupling of integrated optical modulator 14 respectively, again through after the polarization-maintaining coupler 15 coupling beam split, enter fiber optic loop 16, form the opposite two-beam in the direction of propagation, once more by turning back to behind the polarization-maintaining coupler 15 in the integrated optical modulator 14, and formation is interfered, interference signal enters detector 12 via single-mode optical-fibre coupler 13, the interference signal that detector 12 will contain angular speed information is converted to electric signal, and amplify, the signal of Sagnac master's sensing ring is through bandpass filter 21, enter after the 2nd A/D22 conversion and carry out the closed loop demodulation among the FPGA24, stride striped and handle and obtain its corresponding angle rate signal, Sagnac also enters after the signal of sensing ring is changed through an A/D23 and carries out the open loop demodulation the FPGA24, obtain its corresponding angle rate signal, Sagnac is compared analysis from the angle rate signal of sensing ring and the angle rate signal of Sagnac master's sensing ring, judge the striped rank of optical fibre gyro work, then the angle rate signal of Sagnac master's sensing ring is revised the most revised angle rate signal output.

The unspecified part of the present invention belongs to general knowledge as well known to those skilled in the art.

Claims (9)

1. method that increases optical fiber gyroscope range is characterized in that realizing by following steps:

(1) makes the two sensing ring light paths of optical fibre gyro

The two sensing ring light paths of optical fibre gyro comprise light source (11), detector (12), single-mode optical-fibre coupler (13), integrated optical modulator (14), polarization-maintaining fiber coupler (15) and fiber optic loop (16), polarization-maintaining fiber coupler (15) is positioned between integrated optical modulator (14) and the fiber optic loop (16), the C1 of polarization-maintaining fiber coupler (15) tail optical fiber, C3 holds respectively and the Y2 of integrated optical modulator (14) tail optical fiber, the Y3 end is connected, the C2 of polarization-maintaining fiber coupler (15) tail optical fiber, the C4 end is connected with two tail optical fibers of fiber optic loop (16) respectively, the Y2 end of integrated optical modulator (14) tail optical fiber, the C1 of polarization-maintaining fiber coupler (15) tail optical fiber and C4 end, fiber optic loop, the C2 of polarization-maintaining fiber coupler (15) tail optical fiber and C3 end, the Y3 end of integrated optical modulator (14) tail optical fiber constitutes Sagnac master's sensing ring, the Y2 end of integrated optical modulator (14) tail optical fiber, polarization-maintaining fiber coupler (15) tail optical fiber C1 and C3 end, the Y3 end of integrated optical modulator (14) tail optical fiber constitutes Sagnac from sensing ring;

(2) adopt digital oblique wave closed-loop policy that the signal of Sagnac master's sensing ring is carried out demodulation and obtain angular speed Ω _M

(3) adopt the digital open loop method that Sagnac is carried out demodulation from the signal of sensing ring and obtain angular speed Ω _S

(4) adopt the range of striding striped method increase Sagnac master sensing ring;

(5) the angular speed Ω that utilizes Sagnac to obtain from the sensing ring demodulation _SThe angular speed Ω that demodulation obtains to Sagnac master's sensing ring _MCarry out the striped rank and judge and rate correction, obtain the angular speed Ω of revised optical fibre gyro _O

2. a kind of method that increases optical fiber gyroscope range according to claim 1 is characterized in that: the striped rank judgement of described step (5) and the step of rate correction:

(1) demarcates optical fibre gyro, obtain the maximum angular speed ± Ω of Sagnac master's sensing ring striped correspondences at different levels _π, ± Ω _{2 π}, ± Ω _{3 π}With ± Ω _{4 π}

(2) when the optical fibre gyro energising started, the demodulation of Sagnac master's sensing ring obtained angular speed Ω _M, Sagnac obtains angular speed Ω from the sensing ring demodulation _S(3) relatively Sagnac obtains angular speed Ω from the sensing ring demodulation _SWith the maximum angular speed of striped correspondences at different levels, judge the striped rank that Sagnac master's sensing ring is in; (4) utilize the angular speed Ω of the maximum angular speed of place striped correspondence to Sagnac master's sensing ring _MRevise, promptly obtain the angular speed Ω of the final output of optical fibre gyro _O

3. a kind of method that increases optical fiber gyroscope range according to claim 2 is characterized in that: described striped rank is judged and the standard of rate correction is:

When | Ω _S|≤Ω _πThe time, Ω _O=Ω _M

Work as Ω _π≤ Ω _S≤ Ω _{2 π}The time, Ω _O=Ω _M+ Ω _{2 π}

When-Ω _{2 π}≤ Ω _S≤-Ω _πThe time, Ω _O=Ω _M-Ω _{2 π}

Work as Ω _{2 π}≤ Ω _S≤ Ω _{3 π}The time, Ω _O=Ω _M+ Ω _{3 π}

When-Ω _{3 π}≤ Ω _S≤-Ω _{2 π}The time, Ω _O=Ω _M-Ω _{3 π}

Work as Ω _{3 π}≤ Ω _S≤ Ω _{4 π}The time, Ω _O=Ω _M+ Ω _{4 π}

When-Ω _{4 π}≤ Ω _S≤-Ω _{3 π}The time, Ω _O=Ω _M-Ω _{4 π}

4. a kind of method that increases optical fiber gyroscope range according to claim 1, it is characterized in that: the loss of each welding point of described polarization-maintaining fiber coupler (15) tail optical fiber and integrated optical modulator (14) tail optical fiber and fiber optic loop (16) tail optical fiber is less than 0.1dB, and cross-talk is less than-30dB.

5. a kind of method that increases optical fiber gyroscope range according to claim 1 is characterized in that: the length of described Sagnac master's sensing ring is 300～3000m.

6. a kind of method that increases optical fiber gyroscope range according to claim 1 is characterized in that: described Sagnac is 20～30m from the length of sensing ring, angular speed that can responsive 1～2000 °/s.

7. a kind of method that increases optical fiber gyroscope range according to claim 1, it is characterized in that: described Sagnac master's sensing ring and Sagnac adopt two-way A/D conversion to gather the signal of response from sensing ring, Sagnac is from the not filtering of signal of sensing ring, directly change by an A/D (23), the signal of Sagnac master's sensing ring carries out bandpass filtering (21) back to be changed by the 2nd A/D (22).

8. a kind of method that increases optical fiber gyroscope range according to claim 1 is characterized in that: Sagnac master's sensing ring of the digital oblique wave closed-loop policy of described employing, the Sagnac that adopts the digital open loop method are finished by a cover signal processing circuit from signal Processing such as the modulation of the two paths of signals of sensing ring and angular speed corrections.

9. a kind of method that increases optical fiber gyroscope range according to claim 8, it is characterized in that: described signal processing circuit comprises bandpass filter (21), the one A/D (23), the 2nd A/D (22), D/A (25), signal amplifier (26) and FPGA (24), the signal of detector output is through bandpass filter (21), the 2nd A/D (22), FPGA (24), D/A (25) and signal amplifier (26) form the closed loop of Sagnac master's sensing ring and separate mediation control, and the signal of detector output is through an A/D (23), FPGA (24), D/A (25) and signal amplifier (26) form the open loop demodulation of Sagnac from sensing ring.

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