CN113720321A - Temperature compensation system of fiber-optic gyroscope - Google Patents
Temperature compensation system of fiber-optic gyroscope Download PDFInfo
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- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/58—Turn-sensitive devices without moving masses
- G01C19/64—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams
- G01C19/72—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers
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Abstract
The invention provides a temperature compensation system of a fiber-optic gyroscope, which utilizes the temperature sensitivity characteristic of the original Y waveguide in an optical fiber path to design a scheme for replacing the temperature sensor in the original scheme to carry out temperature compensation. A plurality of parameters changing along with temperature exist in a Y waveguide of a core device of the optical fiber gyroscope, an electro-optic conversion coefficient parameter is directly related to the temperature error of the gyroscope, the electro-optic conversion coefficient parameter of the Y waveguide is tracked in real time by designing a certain modulation and demodulation and closed-loop control algorithm, parameter value information with stronger error correlation and better real-time performance of a temperature sensor in comparison with the traditional scheme is obtained, and a traditional temperature error compensation model is combined to replace temperature independent variable information in the model, so that a more direct and effective temperature compensation system can be realized.
Description
Technical Field
The invention relates to the field of optical fiber sensing in the photoelectronic technology, in particular to a temperature compensation system of an optical fiber gyroscope.
Background
The fiber optic gyroscope is an inertial gyroscope instrument based on the Sagnac effect, is designed in an all-solid state, has no moving and wearing parts, long service life, high reliability and relatively simple manufacturing process, and is easier to realize batch manufacturing and large-scale application. The optical fiber gyroscope has flexible structural design, the measurement precision is in direct proportion to the product of the diameter of a sensitive component, namely an optical fiber ring, and the length of an optical fiber in the ring, so that the optical fiber gyroscope can be designed into a product meeting different requirements, at present, a plurality of application fields of sea, land and air space are covered, and the precision covers at least five orders of magnitude.
Most of the world optical fiber gyro products adopt an interference type digital closed loop scheme, and an optical path comprises an optical fiber ring and LiNbO3Multifunctional integrated optical device (Y waveguide for short), light source and other functional components. Because the optical fiber light path has certain temperature sensitivity, the change of the environmental temperature can cause the scale factor of the optical fiber gyroscope and the zero offset drift error, and in the occasion with higher performance requirement, a control means must be adopted, and the corresponding scheme mainly comprises temperature control, temperature compensation and the like. The purpose of temperature control is to provide a stable working temperature environment for the fiber-optic gyroscope measurement system, and the specific schemes including TEC temperature control, heating temperature control and the like all pay the cost of product volume, weight, power consumption and longer stabilization time. Because the product adaptability of the temperature control scheme is poor, the temperature control scheme is only applied to occasions with corresponding conditions, such as ships, satellites and the like. The temperature compensation is to judge and eliminate the error by establishing the mathematical model relation between the temperature information and the gyro output error, can improve the gyro output precision under the condition of not influencing the volume and the weight of the original system, and is adopted by most optical fiber gyro measurement systems.
In the existing optical fiber gyroscope products, temperature measurement chips or platinum resistors and the like are adopted to collect temperature information near the sensitive components of the optical fiber gyroscope. The problems of this solution are: the installation position of the temperature measuring device and the sensitive light path have a certain interval, and the temperature measuring device can only indirectly reflect the temperature change of the sensitive loop, so that the accuracy and the real-time performance are poor. If the temperature measuring device can be directly designed in the optical fiber light path and directly reflects the temperature error generated by the sensitive part of the gyroscope, the accuracy and the real-time performance are greatly improved, and the more effective temperature compensation effect is achieved. From analysis of various aspects such as temperature characteristics and information extractability of each optical device, it is considered that LiNbO is present in the optical path of the optical fiber3Multifunctional integrated optical device (Y waveguide) meets design requirements.
Disclosure of Invention
The invention provides a temperature compensation system of a fiber-optic gyroscope, aiming at the technical problems in the prior art, and the temperature compensation system comprises a fiber-optic light path part and a signal processing part, wherein the fiber-optic light path part comprises a wide-spectrum light source, a fiber-optic interferometer and a detector, and the signal processing part comprises an interference signal sampling module, a first demodulation module, a first integration module, a modulation module, a second demodulation module, a second integration module and an error compensation module;
the detector is used for detecting the light wave signals output by the optical fiber interferometer in real time and converting the light wave signals into electric signals; the interference signal sampling module is used for sampling the electric signals to obtain electric signals of a plurality of points or one point in each state; the first demodulation module is used for calculating an electro-optic conversion coefficient change value of the Y waveguide device related to temperature change through a trigonometric function operation relation according to the sampled electric signals; the first integration module is used for performing integration superposition on the electro-optic conversion coefficient change value of the Y waveguide device to obtain a conversion coefficient value; the second demodulation module is used for demodulating and calculating the sampled electric signal and calculating the rotating speed information change value of the fiber-optic gyroscope; the second integration module is used for performing integration and superposition on the rotating speed information change value of the fiber-optic gyroscope to obtain uncompensated rotating speed information; the modulation module is used for generating a modulation waveform and a feedback waveform according to the conversion coefficient value and the uncompensated rotating speed information and outputting the modulation waveform and the feedback waveform to the optical fiber interferometer; the error conversion module is used for carrying out real-time fitting calculation on the scale factor error and the zero offset of the fiber-optic gyroscope by taking uncompensated rotating speed information and the change value of the electro-optic conversion coefficient of the Y waveguide device as input quantities, and carrying out compensation output on the rotating speed information of the fiber-optic gyroscope.
The temperature compensation system of the fiber-optic gyroscope provided by the invention designs a scheme for replacing the temperature sensor in the original scheme to carry out temperature compensation by utilizing the temperature sensitivity characteristic of the original Y waveguide in the optical fiber path. A plurality of parameters changing along with temperature exist in a Y waveguide of a core device of the optical fiber gyroscope, an electro-optic conversion coefficient parameter is directly related to the temperature error of the gyroscope, the electro-optic conversion coefficient parameter of the Y waveguide is tracked in real time by designing a certain modulation and demodulation and closed-loop control algorithm, parameter value information with stronger error correlation and better real-time performance of a temperature sensor in comparison with the traditional scheme is obtained, and a traditional temperature error compensation model is combined to replace temperature independent variable information in the model, so that a more direct and effective temperature compensation system can be realized.
Drawings
Fig. 1 is a schematic structural diagram of a temperature compensation system of a fiber-optic gyroscope according to the present invention;
FIG. 2 is a schematic diagram of a four-state bias modulation signal;
FIG. 3 is a schematic diagram of a closed loop stable output interferometric output signal;
FIG. 4 is a schematic diagram of an interference output signal of a Y waveguide device after the electro-optic conversion coefficient is changed;
fig. 5 is a schematic flow chart of a modulation and demodulation and closed loop tracking algorithm.
In the drawings, the names of the components represented by the respective reference numerals are as follows:
1. the device comprises an optical fiber light path part, 2, a signal processing part, 3, a wide-spectrum light source, 4, an optical fiber coupler, 5, a Y waveguide device, 6, an optical fiber ring, 7, a detector, 8, an interference signal sampling module, 9, a first demodulation module, 10, a first integration module, 11, a reference standard generation module, 12, a second demodulation module, 13, a second integration module, 14, a modulation module, 15, an error compensation module, 16 and a rotating speed information output module.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
LiNbO3The multifunctional integrated optical device is a device for realizing polarization filtering, beam splitting/combining and electro-optic phase control in a fiber-optic gyroscope, and one of the most important functions of the multifunctional integrated optical device is phase modulation, namely, a controllable phase difference is provided between two beams of Y-branch light. The working foundation for realizing the phase modulation part is that the substrate material of the device has linear electro-optic effect, LiNbO3The refractive index of the crystal material is linearly changed along with the magnitude of the applied electric field. An electric field is applied through phase modulation electrodes on two sides of the waveguide, so that the refractive index of the waveguide area is changed, the physical optical path (the product of the propagation length and the refractive index) of the light is linearly changed along with the applied voltage when the light is transmitted, and the phase of the output light wave is also linearly changed. When square wave voltage signals with half period equal to the transition time of the optical fiber ring are added to the two branches of the Y-branch waveguide, phase difference proportional to the amplitude of the square wave can be generated between the two light waves transmitted oppositely. The measure of the magnitude of the electro-optic effect of the material is the electro-optic coefficient
Refractive index of refraction
The variation with electric field is represented by:
wherein n is the refractive index; e is the electric field strength. The phase shift generated between the two input light waves caused by the external electric field is set as
And then:
in the formula:
is the wavelength of light from the light source;
is the overlap integral of the electric field and the optical field; g is the distance between two electrodes; v is the voltage on the electrode. Wherein the ratio of voltage to light wave phase difference can be defined as the electro-optic conversion coefficient Kt：
Wherein n is,
、
L and G are all changed under the influence of temperature, and particularly n has the largest influence with the change of the temperature and is at least 2 orders of magnitude higher than other influencing factors and has a basically monotonous linear relation with the temperature. With the maturity of the Y waveguide manufacturing technology, the correlation rule of the Y waveguide electro-optic conversion coefficient and the temperature in the optical path of the fiber optic gyroscope is determined (linearly and negatively correlated with the temperature, and the change is about 4% -7% every 100 ℃), if a scheme can be designed to track the change of the Y waveguide electro-optic conversion coefficient in real time and realize the real-time output of higher resolution, the original temperature measuring device can be abandoned, the fitting compensation can be directly realized with the output error of the gyroscope, and the temperature compensation effect can be improved.
In order to realize more effective temperature compensation and overcome the problem of poor correlation between temperature information acquired in the current scheme and gyro errors, a scheme for replacing the temperature sensor in the original scheme to carry out temperature compensation is designed by utilizing the temperature sensitivity of the original Y waveguide device in the optical fiber path. A plurality of parameters of the Y waveguide device changing along with the temperature are directly related to the gyro error, and the invention tracks parameters of the Y waveguide electro-optic conversion coefficient in real time through the designed modulation and demodulation and closed-loop control algorithm, thereby realizing more direct and effective compensation.
Referring to fig. 1, the temperature compensation system of the fiber-optic gyroscope of the present invention is provided, which mainly includes a fiber-optic light path portion 1 and a signal processing portion 2, wherein the fiber-optic light path portion 1 includes a wide-spectrum light source 3, a fiber-optic interferometer and a detector 7, and the signal processing portion 2 includes an interference signal sampling module 8, a first demodulation module 9, a first integration module 10, a modulation module 14, a second demodulation module 12, a second integration module 13 and an error compensation module 15.
The optical fiber interferometer comprises an optical fiber coupler 4, a Y waveguide device 5 and an optical fiber ring 6, wherein the wide-spectrum light source 3, the optical fiber coupler 4, the Y waveguide device 5 and the optical fiber ring 6 are sequentially connected on an optical path, and the detector 7 is used for detecting the optical wave signals returned to the optical fiber coupler 4 by the Y waveguide device 5 and converting the optical wave signals into electric signals.
Wherein, the function of each module is:
the detector 7 is used for detecting the light wave signals output by the optical fiber interferometer in real time and converting the light wave signals into electric signals; the interference signal sampling module 8 is used for sampling the electric signals to obtain the electric signals of a plurality of points or one point in each state; the first demodulation module 9 is used for calculating an electro-optic conversion coefficient change value of the Y waveguide device 5 related to temperature change according to the sampled electric signals through a trigonometric function operation relation; the first integration module 10 is used for integrating and superposing the electro-optic conversion coefficient change value of the Y waveguide device 5 to obtain a conversion coefficient value; the second demodulation module 12 is configured to perform demodulation operation on the sampled electrical signal and calculate a rotation speed information change value of the fiber-optic gyroscope; the second integration module 13 is configured to perform integration and superposition on the rotation speed information change value of the fiber optic gyroscope to obtain uncompensated rotation speed information; the modulation module 14 is used for generating a modulation waveform and a feedback waveform according to the conversion coefficient value and the uncompensated rotating speed information, and outputting the modulation waveform and the feedback waveform to the optical fiber interferometer; and the error conversion module is used for performing real-time fitting calculation on the scale factor error and the zero offset of the fiber-optic gyroscope by taking uncompensated rotating speed information and the change value of the electro-optic conversion coefficient of the Y waveguide device 5 as input quantities, and performing compensation output on the rotating speed information of the fiber-optic gyroscope through the rotating speed information output module 16.
Specifically, the interference signal sampling module 8 is directed at the output information of the detector 7 modulated by a given waveform, and generally samples voltage signals of a plurality of points or one point in a certain modulation state; the first demodulation module 9 calculates the change information of the photoelectric conversion coefficient of the Y waveguide device 5 related to the temperature change according to the sampling information (voltage signal) of the modulation state through the operational relationship of the trigonometric function; the first integration module 10 is obtained by performing continuous integration operation and noise reduction processing on the variation quantity on the basis of the original initial value of the electro-optic conversion coefficient, and theoretically, the transition time of each optical fiber ring 6 can realize data updating once in microsecond order; the working principle of the second demodulation module 12 and the second integration module 13 is similar to that of the first demodulation module 9 and the first integration module 10, the second demodulation module 12 demodulates the rotation speed information of the fiber-optic gyroscope from the sampling information of the modulation state, and the second integration module 13 integrates the demodulated rotation speed information of the fiber-optic gyroscope to obtain the uncompensated rotation speed information obtained by integration.
The modulation module 14 generates a modulation waveform and a feedback waveform by taking the reference value generated by the reference generating module 11 as a reference according to the integrated conversion coefficient value and the uncompensated rotating speed information, wherein the modulation waveform is a group of regular waveforms designed according to a trigonometric function rule and the delay characteristic of the optical fiber ring 6, and generates different modulations on two beams of light transmitted clockwise and anticlockwise; the feedback waveform is a digital step wave formed by accumulating uncompensated rotating speed information values, and phase closed-loop control is realized by automatic reset, so that Sagnac phase change caused by the rotating speed is automatically compensated. The error compensation module 15 is an algorithm model which takes uncompensated rotating speed information and an electro-optic conversion coefficient of the Y waveguide device 5 as input quantities, comprehensively considers the conversion coefficient value, the conversion coefficient change speed, relevant high-order information and the like, performs real-time fitting calculation on error quantities such as scale factor deviation, zero deviation and the like of the fiber-optic gyroscope, and further performs real-time correction on uncompensated gyroscope data. The compensated rotating speed information is output through the rotating speed information output module 16, parameters such as scale factor values, zero offset values and the like of the fiber-optic gyroscope or individual parameters of the parameters are corrected, and the sensitivity of the fiber-optic gyroscope to the change of the environmental temperature is greatly reduced.
The signal processing scheme of the invention designs demodulation of parameter value change information of electro-optic conversion coefficients of the Y waveguide device, and the demodulation information is integrated and stabilized to be used as the input of error compensation and also used as a reference standard to control modulation and feedback waveform to be output to the Y waveguide device. The error compensation process also starts from the original: "ambient temperature variation- > optical path affected resulting in gyro error- > temperature sensor information extraction near the optical path- > error compensation with temperature sensor information as reference. "upgrade to: the method comprises the following steps of' environmental temperature change- > optical path affected to cause gyro error- > extraction of Y waveguide electro-optic conversion coefficient information in the optical path- > error compensation with the Y waveguide electro-optic conversion coefficient as a reference. "
Since the electro-optic conversion coefficient of the Y waveguide device varies with temperature, the voltage required for generating the same phase modulation also varies with temperature, and the phase is fixed, so that the varying voltage represents the electro-optic conversion coefficient of the Y waveguide device, and demodulation and tracking are required. The scheme for acquiring the electro-optic conversion coefficient of the Y waveguide device in real time is described by taking a four-state modulation waveform as an example.
In the fiber ring interferometer, the output of two clockwise and counterclockwise light waves after interference can be described as follows:
in the formula
Sagnac phase shift for inertial space rotational speed,
for the feedback phase shift to be realized by the step wave,
the phase shift created for the modulation waveform.
The modulation waveform (voltage signal) periodically acts on two clockwise and anticlockwise coherent light waves in the interferometer through a Y waveguide modulation electrode according to a certain time sequence, and the generated phase difference is respectively as follows:
each phase offset has an action time
I.e. half the transit time of the fibre optic interferometer. Due to the introduction of phase bias, 4 bias phase differences are generated between clockwise and counterclockwise light waves of the fiber interferometer
That is:
therefore, the first and second electrodes are formed on the substrate,
respectively is as follows:
as shown in fig. 2.
Then at the first of the four-state bias modulation
In time, the interference output of the optical wave can be described as:
the second one
In time, the optical wave interference output can be described as:
as can be seen from the above two formulas (3) and (4), the first of the four-state modulation
In time, the optical wave interference output can be described as:
similarly, in the second of the four-state modulation
In time, the optical wave interference output can be described as:
sagnac phase shift if ring fiber interferometer
Feedback phase shift given in real time by the signal processing section
Compensation, i.e.
Then there is
Two light waves in clockwise and anticlockwise directions are interfered and output to form a straight line, and the position of the straight line corresponding to the change of the modulation waveform is provided with comb-shaped pulses, as shown in figure 3.
When there is error in the electro-optic conversion coefficient of the Y waveguide, the phase difference caused by the modulation waveform becomes the standard value
At times, the interference signal intensity of the two light waves is:
when the closed-loop control has reached equilibrium, i.e.
Is provided with
But now at one
Actually generated in time
Are different, that is, the front and rear two
The interference signals are also no longer equal in time, and the difference is calculated as:
the
I.e. the change value of the electro-optic conversion coefficient of the Y waveguide device, so that when the electro-optic conversion coefficient of the Y waveguide drifts, the half transit time of the interference output of the optical wave
An error appears for the period
As shown in fig. 4.
By the amount of error demodulated
The electro-optic conversion coefficient of the Y waveguide device is subjected to real-time superposition adjustment, and the adjusted coefficient value is used as a reference generated by a modulation waveform and a feedback waveform on the one hand, so that the closed-loop control of the conversion coefficient is balanced again, and the stable signal shown in the figure 2 is realized; on the other hand, the real-time error compensation of the inventive solution is implemented instead of the temperature measurementAnd (6) dynamically inputting.
Referring to fig. 5, the steps of an embodiment of the fiber-optic gyroscope temperature compensation system are as follows:
(1) with reference to the schematic diagram of temperature compensation by using a Y waveguide device, as shown in fig. 5, for a signal processing system of a fiber optic gyroscope, a scheme design of error compensation is developed, specifically:
aiming at the interference signal output by the optical fiber optical path part, a phase modulation waveform meeting the real-time demodulation requirement is designed. Information sampling is performed on the modulated interference output signal, and each state samples a plurality of points or an electric signal of one point.
And respectively demodulating the rotation speed change information and the change information of the electro-optic conversion coefficient of the gyroscope by utilizing the trigonometric function relationship between the sampling result and the modulation waveform. And obtaining the real-time sensitive rotating speed value (namely the uncompensated rotating speed information) and the electric-to-optical conversion coefficient value (namely the conversion coefficient value) of the fiber-optic gyroscope through continuous accumulation integral operation.
The sensitive rotating speed value is accumulated into step waves for realizing the closed loop feedback function, and the electro-optic conversion coefficient is output to serve as a phase modulation waveform and a closed loop feedback waveform as reference on one hand and is output to an error compensation model on the other hand. And the original sensitive rotating speed information of the fiber-optic gyroscope is subjected to data output after real-time compensation through an error compensation model.
(2) Aiming at the extraction of the photoelectric conversion coefficient information of the Y waveguide, a modulation-demodulation and closed-loop tracking algorithm is designed, and the method specifically comprises the following steps:
the reference value of the photoelectric conversion coefficient is set in the algorithm program and can be given according to the test result or given by a self-locking technology, so that the modulation waveform periodically acts on two clockwise and anticlockwise coherent light waves in the interferometer through a Y waveguide modulation electrode according to a certain time sequence, and the generated phase difference is respectively as follows:
each phase offset has an action time
I.e. optical fibre trunkHalf the transit time of the interferometer.
The output signal of the optical fiber interferometer is sampled, the comb-shaped pulse position is avoided during sampling, and the equal number of sampling points between every two pulse shapes is ensured (the pulse corresponds to the modulation wave shape and changes the position).
The sampling result of adjacent transit time is used for demodulating the change information of the rotating speed, the rotating speed value obtained by integration is used for rotating speed feedback, and the interference signals of the adjacent transit time are balanced (the adjacent transit time corresponds to the interference signals in the same modulation period)
And
phase).
In the same transit time, using the front and rear halves
Carrying out subtraction demodulation on the sampling values in the data acquisition module, wherein the integrated result is the photoelectric conversion coefficient value of real-time dynamic output; the photoelectric conversion coefficient is output to a DA converter through a conversion circuit and is used as a gain reference standard for adjusting the DA converter along with temperature change; and the photoelectric conversion coefficient is output to an error compensation model, and the originally demodulated rotating speed information is corrected into output rotating speed information which does not change along with the temperature or output rotating speed information which changes less along with the temperature.
Compared with the prior art, the temperature compensation system of the fiber-optic gyroscope provided by the embodiment of the invention has the following beneficial effects:
(1) in order to solve the problem that a temperature sensor of the optical fiber gyroscope in the prior art can only indirectly reflect the influence of temperature on a sensitive loop and has poor accuracy, an original temperature measurement scheme is abandoned from hardware, a Y waveguide in an optical fiber light path is used as a temperature sensitive device to directly reflect the sensitive temperature error of the optical fiber light path, the resolution ratio is high, and a more effective error compensation effect can be achieved.
(2) The newly designed data demodulation and tracking scheme has good real-time performance, can theoretically realize data updating in the transit time of an optical fiber interferometer, achieves microsecond-order data replacement, and can quickly respond to temperature-related error change in a light path after noise reduction treatment;
(3) the Y waveguide device is directly related to the temperature error of the fiber optic gyroscope, for example, the change information of the electro-optic conversion coefficient of the Y waveguide device also reflects the amplitude type polarization error information of the temperature-related vibration of the fiber optic gyroscope to a great extent, and the latter is one of the most important reasons of the zero offset error caused by the optical path of the fiber optic gyroscope.
It should be noted that, in the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to relevant descriptions of other embodiments for parts that are not described in detail in a certain embodiment.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (7)
1. The temperature compensation system of the fiber-optic gyroscope is characterized by comprising an optical fiber light path part and a signal processing part, wherein the optical fiber light path part comprises a wide-spectrum light source, an optical fiber interferometer and a detector, and the signal processing part comprises an interference signal sampling module, a first demodulation module, a first integration module, a modulation module, a second demodulation module, a second integration module and an error compensation module;
the detector is used for detecting the light wave signals output by the optical fiber interferometer in real time and converting the light wave signals into electric signals;
the interference signal sampling module is used for sampling the electric signals to obtain electric signals of a plurality of points or one point in each state;
the first demodulation module is used for calculating an electro-optic conversion coefficient change value of the Y waveguide device related to temperature change through a trigonometric function operation relation according to the sampled electric signals;
the first integration module is used for performing integration superposition on the electro-optic conversion coefficient change value of the Y waveguide device to obtain a conversion coefficient value;
the second demodulation module is used for demodulating and calculating the sampled electric signal and calculating the rotating speed information change value of the fiber-optic gyroscope;
the second integration module is used for performing integration and superposition on the rotating speed information change value of the fiber-optic gyroscope to obtain uncompensated rotating speed information;
the modulation module is used for generating a modulation waveform and a feedback waveform according to the conversion coefficient value and the uncompensated rotating speed information and outputting the modulation waveform and the feedback waveform to the optical fiber interferometer;
the error conversion module is used for carrying out real-time fitting calculation on the scale factor error and the zero offset of the fiber-optic gyroscope by taking uncompensated rotating speed information and the change value of the electro-optic conversion coefficient of the Y waveguide device as input quantities, and carrying out compensation output on the rotating speed information of the fiber-optic gyroscope.
2. The system of claim 1, wherein the fiber optic interferometer comprises a fiber optic coupler, a Y waveguide and a fiber optic ring, the broad spectrum light source, the fiber optic coupler, the Y waveguide and the fiber optic ring are sequentially connected on an optical path, and the detector is configured to detect the light wave signal returned from the Y waveguide to the fiber optic coupler and convert the light wave signal into an electrical signal.
3. The system of claim 1, wherein the interference signal sampling module avoids comb pulse positions when sampling the electrical signal, and the number of sampling points between each state is equal.
4. The system for compensating temperature of a fiber-optic gyroscope according to claim 2, wherein the electrical signal obtained by converting the optical wave signal output by the fiber-optic interferometer detected by the detector is:
in the formula (I), the compound is shown in the specification,
sagnac phase shift for inertial space rotational speed,
for the feedback phase shift to be realized by the step wave,
a phase shift generated for the modulation waveform;
the modulation waveform periodically acts on two clockwise and anticlockwise coherent light waves in the optical fiber interferometer according to a time sequence through a modulation electrode of a Y waveguide device, and the generated phase difference is respectively as follows:
、
、0、
each phase offset has an action time
I.e. half the transit time of the fiber optic interferometer;
the introduction of phase bias can make the clockwise and anticlockwise two light waves of optical fibre interferometer produce 4 bias phase differences
Namely:
therefore, the first and second electrodes are formed on the substrate,
respectively is as follows:
。
5. the fiber optic gyroscope temperature compensation system of claim 4, wherein the first of the four-state bias modulations is at
In time, the interference output of the optical wave can be described as:
the second one
In time, the optical wave interference output can be described as:
according to equations (3) and (4), the first of the four-state modulation
In time, the optical wave interference output can be described as:
similarly, in the second of the four-state modulation
In time, the optical wave interference output can be described as:
6. the temperature compensation system of fiber-optic gyroscope of claim 5, wherein when there is an error in the electro-optic conversion coefficient of the Y-waveguide device, the phase difference caused by the modulation waveform becomes a standard value
At times, the interference signal intensity of the two light waves is:
when the closed-loop control reaches equilibrium, i.e.
Equation (6) can be expressed as:
7. the system of claim 6, wherein the change value of the electro-optic conversion coefficient of the Y waveguide device is two before and two after
Difference of interference signal in time:
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| CN115077567A (en) * | 2022-08-18 | 2022-09-20 | 中国船舶重工集团公司第七0七研究所 | Scale factor compensation system and method based on waveguide reset error |
| CN115628733A (en) * | 2022-12-08 | 2023-01-20 | 中国船舶集团有限公司第七〇七研究所 | Method for eliminating phase voltage error of Y waveguide, stress compensator and fiber-optic gyroscope |
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| CN115628733A (en) * | 2022-12-08 | 2023-01-20 | 中国船舶集团有限公司第七〇七研究所 | Method for eliminating phase voltage error of Y waveguide, stress compensator and fiber-optic gyroscope |
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