JP2969212B2 - Optical interference angular velocity meter - Google Patents
Optical interference angular velocity meterInfo
- Publication number
- JP2969212B2 JP2969212B2 JP32050495A JP32050495A JP2969212B2 JP 2969212 B2 JP2969212 B2 JP 2969212B2 JP 32050495 A JP32050495 A JP 32050495A JP 32050495 A JP32050495 A JP 32050495A JP 2969212 B2 JP2969212 B2 JP 2969212B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- output
- value
- addition result
- cumulative addition
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Gyroscopes (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】この発明は例えば移動体の姿
勢検出等に利用することができる光干渉角速度計に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical interference gyro which can be used, for example, for detecting the attitude of a moving body.
【０００２】[0002]
【従来の技術】図２に従来のデジタル位相変調方式を採
る光干渉角速度計の例を簡略に示す。レーザーなどの光
源１からの光はビームスプリッター２で２分され、その
２つの光は例えば偏波面保存ファイバーのコイルよりな
るループ状光伝送路３にその両端から右回り光４と左回
り光５として入射される。2. Description of the Related Art FIG. 2 schematically shows an example of a conventional optical interference gyro employing a digital phase modulation method. Light from a light source 1 such as a laser is split into two by a beam splitter 2, and the two lights are directed to a loop-shaped optical transmission path 3 composed of, for example, a polarization preserving fiber coil from both ends of the clockwise light 4 and the counterclockwise light 5. Incident.
【０００３】ビームスプリッター２と光伝送路３の間に
は光位相変調器６が挿入され、変調信号発生器７よりの
変調信号および、デジタル−アナログ変換器８によりア
ナログ値となったランプ信号にしたがって入射光の位相
を変調する。光伝送路３および光位相変調器６を伝搬
し、これよりでた両光はビームスプリッター２で合波し
て干渉する。[0003] An optical phase modulator 6 is inserted between the beam splitter 2 and the optical transmission line 3 to convert a modulation signal from a modulation signal generator 7 and a ramp signal into an analog value by a digital-analog converter 8. Therefore, the phase of the incident light is modulated. The light propagating through the optical transmission line 3 and the optical phase modulator 6 is combined by the beam splitter 2 and interferes.
【０００４】この干渉光は光電変換器９でその強度に応
じた電気信号に変換され、アナログ−デジタル変換器１
０によりデジタル値に変換される。復調器１１ではこれ
を変調信号を参照信号として同期検波し復調する。右回
り光と左回り光が干渉したときの両光の位相差と、干渉
光強度との関係は図３の曲線２１のようになる。光伝送
路３に角速度が入力されていない状態では、変調信号発
生器７による変調により、右回り光と左回り光との位相
差は図３の曲線２２のようにゼロ位相を中心に正、負に
同量ずつ時間τごとに変化し、干渉光強度は２３のよう
に一定となるため復調器１１の出力は零になる。[0004] The interference light is converted into an electric signal corresponding to the intensity by the photoelectric converter 9 and the analog-to-digital converter 1
It is converted to a digital value by 0. The demodulator 11 synchronously detects and demodulates the modulated signal as a reference signal. The relationship between the phase difference between the right-handed light and the left-handed light when the left-handed light interferes and the interference light intensity is as shown by a curve 21 in FIG. When the angular velocity is not input to the optical transmission line 3, the phase difference between the clockwise light and the counterclockwise light is positive and centered around the zero phase as shown by a curve 22 in FIG. The interference light intensity changes by the same amount every time τ, and the interference light intensity becomes constant like 23, so that the output of the demodulator 11 becomes zero.
【０００５】一方、光伝送路３に角速度が入力される
と、サニャック効果によりその角速度の方向と大きさに
応じて右回り光と左回り光との間に位相差φR が生じ
る。この位相差φR の影響により右回り光と左回り光と
の位相差は図３の曲線２４に示すように零位相からφR
だけずれた位相を中心に正、負に同量ずつ時間τごとに
変化する。従って復調器１１では２５のように時間τご
とのレベル差と、変調信号に対する位相（正相か逆相
か）とが検出される。この出力をもとに復調器１１の出
力が零になるような負帰還信号（ステップ値信号）をス
テップ値生成器１２で発生させる。このステップ値信号
（φS ）を時間τごとに累積加算したものがランプ信号
生成器１３から出力されるランプ信号ＬＡ（図４Ａ）で
ある。ランプ信号ＬＡにより受ける光の位相変調は、位
相変調器が光伝送路の片端に配置されているため、右回
り光と左回り光とでは時間τだけずれている。そのため
ランプ信号ＬＡにより生じる両光間の位相差はステップ
値φS （図４Ｂ）と等しくなる。従って負帰還が安定状
態である場合ステップ値φS は入力角速度で生じるサニ
ャック位相差φR と等しくなる。On the other hand, when an angular velocity is input to the optical transmission line 3, a phase difference φ R is generated between clockwise light and counterclockwise light according to the direction and magnitude of the angular velocity due to the Sagnac effect. Due to the influence of the phase difference φ R , the phase difference between the clockwise light and the counterclockwise light is changed from zero phase to φ R as shown by a curve 24 in FIG.
The phase is shifted by the same amount in the positive and negative directions at every time τ with the phase shifted by the center. Accordingly, the demodulator 11 detects the level difference for each time τ and the phase (normal phase or reverse phase) with respect to the modulated signal as indicated by 25. Based on this output, the step value generator 12 generates a negative feedback signal (step value signal) such that the output of the demodulator 11 becomes zero. The ramp signal LA (FIG. 4A) output from the ramp signal generator 13 is obtained by cumulatively adding the step value signal (φ s ) for each time τ. The phase modulation of the light received by the ramp signal LA is shifted by the time τ between the clockwise light and the counterclockwise light because the phase modulator is arranged at one end of the optical transmission line. Therefore, the phase difference between the two lights caused by the ramp signal LA becomes equal to the step value φ S (FIG. 4B). Thus negative feedback step value phi S when a stable state is equal to the Sagnac phase difference phi R caused by the input angular velocity.
【０００６】光干渉角速度計では一般に外部システムと
のインターフェイスを簡略化するため、ランプ信号ＬＡ
にフライバック（ステップ値の累積加算結果が±２ｎπ
の位相差に相当する大きさに達したとき、±２ｎπ分差
し引く行為）が生じたときにランプ信号生成器１３から
フライバック方向に応じてパルスを外部システムに出力
し、外部システムではこのパルスの周波数から回転角速
度ωを算出している。つまり次式に示すように、このパ
ルスが一定の回転角度θを表す。Generally, in the optical interference gyro, a ramp signal LA is used to simplify an interface with an external system.
Flyback (the cumulative addition result of the step value is ± 2nπ
When a magnitude corresponding to the phase difference of () is reached, an action of subtracting ± 2nπ) is output from the ramp signal generator 13 to the external system in accordance with the flyback direction. The rotation angular velocity ω is calculated from the frequency. That is, as shown in the following equation, this pulse represents a constant rotation angle θ.
【０００７】 Ｔ＝２ｎπ／φR ・τ＝２ｎπ／ＫS ω・τ θ＝ωＴ＝２ｎπ／ＫS ・τ（＝Ｃｏｎｓｔ．） ＫS ：サニャック係数（光学系により決定） ω ：入力角速度 Ｔ：フライバックを起こすまでの時間(. = Const) [0007] T = 2nπ / φ R · τ = 2nπ / K S ω · τ θ = ωT = 2nπ / K S · τ K S: Sagnac coefficient (determined by the optical system) ω: input angular velocity T : Time until flyback occurs
【０００８】[0008]
【発明が解決しようとする課題】上述したように復調器
１１では、変調信号に同期して光電変換器９から出力さ
れる干渉光の強度を同期検波するため、アナログ−デジ
タル変換器１０では変調信号の同期τに同期してＡＤ変
換動作を行なわなくてはならない。このため、復調器１
１から得られる復調信号は１サンプル点の検出強度を利
用するため、ノイズの影響を大きく受け、誤差が比較的
大きく発生するおそれがある。As described above, the demodulator 11 synchronously detects the intensity of the interference light output from the photoelectric converter 9 in synchronization with the modulation signal. The AD conversion operation must be performed in synchronization with the signal synchronization τ. Therefore, the demodulator 1
Since the demodulated signal obtained from 1 uses the detection intensity at one sample point, it is greatly affected by noise, and a relatively large error may occur.
【０００９】従って１サンプル点だけの光干渉信号のレ
ベルを利用して入力された角速度を計測するとノイズの
混入率が高いため、誤差値が大きくなる不都合がある。
この発明の目的は計測ダイナミックレンジが従来より広
い光干渉角速度計を提供しようとするものである。Therefore, when the input angular velocity is measured by using the level of the optical interference signal at only one sample point, the mixing ratio of noise is high, and the error value is disadvantageously increased.
An object of the present invention is to provide an optical interference gyro having a wider measurement dynamic range than before.
【００１０】[0010]
【課題を解決するための手段】この発明ではアナログ−
デジタル変換器のＡＤ変換動作の繰返しを変調信号の周
期τと比較して高速化すると共に、高速でＡＤ変換して
得られた多数のサンプルデータを変調信号の同期τ毎に
積算し平均化処理を行ない、その積算平均化処理を施し
たサンプルデータを復調器に入力し復調する構成とした
ものである。According to the present invention, an analog-
The repetition of the A / D conversion operation of the digital converter is speeded up by comparing with the period τ of the modulation signal, and a large number of sample data obtained by performing the A / D conversion at a high speed are integrated for each synchronization τ of the modulation signal and averaged. , And the sampled data subjected to the integration and averaging process is input to a demodulator and demodulated.
【００１１】この発明の構成によれば、変調信号の周期
τ内において、複数のサンプル点をＡＤ変換し、その複
数のサンプルデータを積算して平均化処理し、その平均
化処理を施したデータを復調器に入力して同期検波する
から、復調器に入力される平均化処理されたデータの値
はサンプル数をＮとした場合、１／√Ｎだけ誤差値を小
さくすることができる。従ってこの発明によれば最大入
力値はそのままで誤差値の小さい、いわゆるダイナミッ
クレンジが広い角速度検出信号を得ることができる光干
渉角速度計を提供することができる。According to the structure of the present invention, a plurality of sample points are AD-converted within the period τ of the modulation signal, the plurality of sample data are integrated and averaged, and the averaged data is obtained. Is input to the demodulator and synchronous detection is performed. Therefore, when the number of samples is N, the error value of the averaged data input to the demodulator can be reduced by 1 / √N. Therefore, according to the present invention, it is possible to provide an optical interference gyro which can obtain an angular velocity detection signal having a small error value while maintaining a maximum input value as it is and having a wide dynamic range.
【００１２】[0012]
【発明の実施の形態】図１に示す実施例を用いてこの発
明の実施の形態を説明する。図１において、図２と対応
する部分には同一符号を付して示す。この発明ではアナ
ログ−デジタル変換器１０のＡ−Ｄ変換動作の繰返し周
期を変調信号の周期より小さく選定する。例えば変調信
号の周期τ内において１００回ＡＤ変換動作を行なわせ
るようにアナログ−デジタル変換器１０に与えるクロッ
クの周波数を選定する。このように構成することによ
り、アナログ−デジタル変換器１０は変調信号の周期τ
毎に１００個のサンプルデータを出力する。DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the embodiment shown in FIG. In FIG. 1, parts corresponding to those in FIG. 2 are denoted by the same reference numerals. In the present invention, the repetition period of the AD conversion operation of the analog-digital converter 10 is selected to be smaller than the period of the modulation signal. For example, the frequency of the clock supplied to the analog-digital converter 10 is selected so that the AD conversion operation is performed 100 times within the period τ of the modulation signal. With this configuration, the analog-to-digital converter 10 can control the period τ of the modulation signal.
Each time, 100 pieces of sample data are output.
【００１３】この発明では、この複数のサンプルデータ
を積算平均化処理器１４に入力し、積算平均化処理器１
４によって周期τ毎にサンプルデータを積算し、平均化
処理を施し、周期τに同期させて平均化処理データを出
力させ、復調器１１に入力する。従って、この発明によ
る光干渉角速度計によれば、復調器１１に入力される光
強度信号は複数のサンプルデータを積算し平均化処理し
たデータであるから、ノイズによる影響をサンプル数Ｎ
とした場合１／√Ｎに減少させることができる。つまり
上記した実施例ではノイズによる影響を１／１０に軽減
することができる。よって最大入力値はそのままで誤差
値が小さい光干渉角速度計を得ることができる。According to the present invention, the plurality of sample data are input to the integrated averaging processor 14 and the integrated averaging processor 1
In step 4, sample data is integrated for each period τ, an averaging process is performed, and averaging process data is output in synchronization with the period τ. Therefore, according to the optical interference gyro according to the present invention, the light intensity signal input to the demodulator 11 is data obtained by integrating and averaging a plurality of sample data.
Can be reduced to 1 / √N. That is, in the above embodiment, the influence of noise can be reduced to 1/10. Therefore, an optical interference gyro with a small error value can be obtained without changing the maximum input value.
【００１４】[0014]
【発明の効果】以上説明したように、この発明によれば
アナログ−デジタル変換器１０のＡＤ変換動作の繰返し
周波数を高めると共に、アナログ−デジタル変換器１０
の出力側にＡＤ変換出力を積算し平均化処理を施こす積
算平均化処理器１４を設けるだけの簡単な構成により、
計測ダイナミックレンジを広げられ、例えば精度の高い
光干渉角速度計を得ることができる。よって安価で従来
より計測ダイナミックレンジの広い光干渉角速度計を提
供することができる実益が得られる。As described above, according to the present invention, the repetition frequency of the AD conversion operation of the analog-to-digital converter 10 is increased and the analog-to-digital
With the simple configuration of simply providing the integrated averaging processor 14 for integrating the A / D conversion output and performing the averaging process on the output side of
The measurement dynamic range can be widened, and for example, a highly accurate optical interference angular velocity meter can be obtained. Therefore, there is obtained an advantage that an optical interference gyro which is inexpensive and has a wider measurement dynamic range than before can be provided.
【図１】この発明の一実施例を示すブロック図。FIG. 1 is a block diagram showing one embodiment of the present invention.
【図２】従来の技術を説明するためのブロック図。FIG. 2 is a block diagram for explaining a conventional technique.
【図３】図２に示した従来の光干渉角速度計の動作を説
明するための波形図。FIG. 3 is a waveform chart for explaining the operation of the conventional optical interference gyro shown in FIG. 2;
【図４】図３と同様の波形図。FIG. 4 is a waveform diagram similar to FIG.
１ 光源 ２ ビームスプリッター ３ 光伝送路 ４ 右回り光 ５ 左回り光 ６ 光位相変調器 ７ 変調信号発生器 ８ デジタル−アナログ変換器 １０ アナログ−デジタル変換器 １１ 復調器 １２ ステップ値生成器 １３ ランプ信号生成器 １４ 積算平均化処理器 Reference Signs List 1 light source 2 beam splitter 3 optical transmission line 4 clockwise light 5 counterclockwise light 6 optical phase modulator 7 modulation signal generator 8 digital-analog converter 10 analog-digital converter 11 demodulator 12 step value generator 13 lamp signal Generator 14 Integral averaging processor
Claims (1)
スプリッターと、ビームスプリッターよりの２つの光が
右回り光および左回り光として入射されるループ状光伝
送路と、その光伝送路から出射される左右両回り光を干
渉させる干渉手段と、干渉光が供給されその強度に応じ
た電気信号を出力する光電変換器と、上記光伝送路と上
記ビームスプリッターとの間に挿入され、電気的に制御
されて光の位相を偏位させる光位相変調器と、上記光伝
送路の光の伝搬時間τの２倍の周期を持ち、デューティ
が５０％の方形波であって、上記光位相変調器に印加す
ることにより上記右回り光と左回り光との間に時間τご
とに正負同量の位相差を交互に与えるための変調信号を
発生する変調信号発生器と、上記光電変換器の出力を上
記変調信号の周波数より高い繰返し周波数でデジタル値
に変換するアナログ−デジタル変換器と、このアナログ
−デジタル変換器の変換出力を上記変調信号の周期毎に
積算し平均化処理して上記変調信号の周期に従って出力
する積算平均処理手段と、この積算平均処理手段の出力
を上記変調信号にしたがって同期検波し復調する復調器
と、その復調器の出力をもとに上記光伝送路に入力され
る角速度により上記左右両光間に生じるサニャック位相
差を相殺する大きさおよび極性を有するステップ値を生
成するステップ値生成器と、そのステップ値を時間τご
とに累積加算し、その累積加算結果が光の位相差に換算
して２ｎπラジアン（ｎは自然数）に相当する正の閾値
を越える場合は累積加算結果から正の閾値を差し引いた
値を累積加算結果として出力するとともに正の角度パル
スを出力し、同様に−２ｎπラジアンに相当する負の閾
値を下回る場合は累積加算結果に正の閾値を加えた値を
累積加算結果として出力するとともに負の角度パルスを
出力し、累積加算結果が正負の閾値の間にある場合はそ
のまま累積加算結果を出力するランプ信号生成器と、累
積加算結果をアナログ値に変換し、上記光位相変調器に
印加するデジタル−アナログ変換器と、 によって構成したことを特徴とする光干渉角速度計。1. A light source, a beam splitter for splitting light from the light source into two, a loop-shaped optical transmission line into which two lights from the beam splitter are incident as clockwise light and counterclockwise light, and the optical transmission line Interfering means for interfering both right and left light emitted from the, a photoelectric converter that is supplied with interference light and outputs an electric signal according to the intensity thereof, is inserted between the optical transmission path and the beam splitter, An optical phase modulator electrically controlled to shift the phase of light, and a square wave having a period twice as long as the propagation time τ of light in the optical transmission line and a duty of 50%, A modulation signal generator for applying a phase modulator to generate a modulation signal for alternately giving the same positive and negative phase difference between the clockwise light and the counterclockwise light every time τ; The output of the modulator An analog-to-digital converter that converts a digital value at a higher repetition frequency, an integration that integrates the conversion output of the analog-to-digital converter for each cycle of the modulation signal, averages the output, and outputs the result according to the cycle of the modulation signal. Averaging processing means, a demodulator for synchronously detecting and demodulating the output of the integrated averaging processing means in accordance with the modulation signal, and the left and right lights based on the angular velocity input to the optical transmission line based on the output of the demodulator. A step value generator that generates a step value having a magnitude and polarity that cancels out the Sagnac phase difference that occurs between them, accumulatively adds the step value for each time τ, and converts the accumulated addition result into a phase difference of light. When a positive threshold corresponding to 2nπ radians (n is a natural number) is exceeded, a value obtained by subtracting the positive threshold from the cumulative addition result is output as the cumulative addition result. When a positive angle pulse is output, and similarly, when the value falls below a negative threshold value corresponding to −2nπ radians, a value obtained by adding a positive threshold value to the cumulative addition result is output as the cumulative addition result, and a negative angle pulse is output. A ramp signal generator that outputs the cumulative addition result as it is when the cumulative addition result is between the positive and negative threshold values, and a digital-analog converter that converts the cumulative addition result into an analog value and applies the analog value to the optical phase modulator. An optical interference gyro, characterized by comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32050495A JP2969212B2 (en) | 1995-12-08 | 1995-12-08 | Optical interference angular velocity meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32050495A JP2969212B2 (en) | 1995-12-08 | 1995-12-08 | Optical interference angular velocity meter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09159464A JPH09159464A (en) | 1997-06-20 |
| JP2969212B2 true JP2969212B2 (en) | 1999-11-02 |
Family
ID=18122195
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP32050495A Expired - Fee Related JP2969212B2 (en) | 1995-12-08 | 1995-12-08 | Optical interference angular velocity meter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2969212B2 (en) |
-
1995
- 1995-12-08 JP JP32050495A patent/JP2969212B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH09159464A (en) | 1997-06-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JPH10300479A (en) | Method and device for suppressing cross coupling in optical fiber gyroscope adapting overmodulation | |
| CN108519079B (en) | Method for reducing crosstalk through six-state modulation of double closed-loop fiber-optic gyroscope | |
| JP2878441B2 (en) | Fiber optic measurement device, gyrometer, central navigation, and stabilization system | |
| EP0935738A2 (en) | Backscatter error reducer for interferometric fiber optic gyroscope | |
| JP3866769B2 (en) | Coherent pickup error canceling device | |
| JPH0654236B2 (en) | Digital phase lamp type optical interference gyro | |
| US5146292A (en) | Method for self-correction of a fiber gyroscope with a 3×3-coupler | |
| JP2969212B2 (en) | Optical interference angular velocity meter | |
| KR100581158B1 (en) | How to measure the phase difference of light waves propagated through two paths | |
| US7187448B2 (en) | Nonreciprocal phase shift fiber-optic gyrometer | |
| JPH11108669A (en) | Optical fiber gyro | |
| US5345307A (en) | Linear phase ramp type fiber optic gyro having ramp reset and reset connection signals | |
| JP4520560B2 (en) | Method and apparatus for determining the number of fringes of an optical fiber gyro | |
| JP3272333B2 (en) | Fiber optic gyro | |
| JP3894925B2 (en) | Closed loop optical fiber gyro | |
| CN114719837B (en) | Six-state modulation and demodulation method and system for digital closed-loop optical fiber gyroscope | |
| WO2000003202A1 (en) | Optical fiber gyro | |
| JP3239237B2 (en) | Closed-loop optical interference gyro | |
| JPH04270914A (en) | Synchronous detector | |
| JP2000055672A (en) | Optical fiber gyro | |
| JPH06221859A (en) | Optical interference angular speed meter | |
| JP2000146597A (en) | Optical fiber gyro | |
| CA2020379C (en) | Digital synthetic serrodyne for fiber optic gyroscope | |
| JP3390943B2 (en) | Optical interference angular velocity meter | |
| JPH09236437A (en) | Optical-interference angular velocity meter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 19990713 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080827 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080827 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090827 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090827 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100827 Year of fee payment: 11 |
|
| LAPS | Cancellation because of no payment of annual fees |