CN115855118B - Method and device for improving stability of scale factors of fiber optic gyroscope - Google Patents
Method and device for improving stability of scale factors of fiber optic gyroscope Download PDFInfo
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Abstract
The embodiment of the invention discloses a method and a device for improving the stability of a scale factor of an optical fiber gyroscope, wherein a scale factor conduction model of the optical fiber gyroscope is firstly determined, then a closed-loop scale factor error transfer function is determined according to the scale factor conduction model, then the spectral distortion of an initial light beam during the transmission of the optical fiber gyroscope is determined according to the closed-loop scale factor error transfer function, and finally the spectrum of the initial light beam is corrected according to the spectral distortion. By using the method, the distortion waveform of the whole optical path of the fiber-optic gyroscope can be corrected, the correction and optimization of the waveform of the whole optical path for transmitting the light beam of the fiber-optic gyroscope can be completed, the symmetry of the waveform can be improved, and the stability of the scale factor of the ultra-high precision fiber-optic gyroscope can be improved.
Description
Technical Field
The invention relates to the technical field of optics, in particular to a method and a device for improving the stability of a scale factor of an optical fiber gyroscope.
Background
The high-precision fiber optic gyroscope is a good angular rate sensor, is widely applied to the fields of navigation in the sea, aviation guidance, land positioning and orientation, mine exploration, intelligent attitude control and the like, and particularly has the advantages of high precision, low noise, high reliability and the like aiming at the field of long-endurance high-precision inertial navigation of a ship, and is beneficial to the large-distance, large-submergence-depth and long-period high-precision navigation and positioning of a large-scale underwater ship.
Along with popularization of high-precision optical fiber inertial navigation system application, the requirements on the performance of the scale factor of the core element optical fiber gyro are higher and higher, and particularly, the long-term stability of the scale factor is outstanding. The main contributor to the influence of scale factor error on navigation positioning accuracy is positioning error caused by coupling of the non-isolated rotational speed with the scale factor error. The above-mentioned errors, if occurring between different voyages, can be compensated by systematic calibration methods, but the above-mentioned scale errors occur during a single voyage with difficulty to suppress. Along with the extension of the single navigation working time of the high-precision optical fiber inertial navigation system, the slow drift of the optical path wavelength forms a main influencing factor causing scale factor fluctuation.
Because the wavelength drift of the fiber optic gyroscope is related to the core optics of the fiber optic gyroscope, including the pair light source, integrated optical chip, fiber optic loops, couplers, and the like. The device is subject to wavelength drift due to environmental fluctuations such as temperature during application. How to build the relation between the wavelength drift of the all-optical path and the change of the scale factors, and further reduce the error of the scale factors by a compensation method, and the method for modeling the waveform distortion of the coupler, the waveguide and the ring all-optical path device and compensating and improving the scale factors is studied.
Disclosure of Invention
The embodiment of the invention provides a method and a device for improving the stability of a scale factor of an optical fiber gyroscope, which can correct the waveform of a full optical path of optical fiber gyroscope light beam transmission and realize the improvement of the stability of the scale factor of the optical fiber gyroscope with ultra-high precision.
According to an aspect of the present invention, there is provided a method for improving the stability of a scale factor of an optical fiber gyro, the method comprising:
determining a scale factor conduction model of the fiber-optic gyroscope;
determining a closed loop scale factor error transfer function from the scale factor conduction model;
according to the closed loop scale factor error transfer function, determining the spectral distortion of an initial light beam during the transmission of the fiber-optic gyroscope;
and correcting the spectrum of the initial light beam according to the spectrum distortion.
Optionally, the determining the scale factor conduction model of the fiber optic gyroscope includes:
determining a scale factor error equation of each functional module according to the light beam transmission process in the fiber-optic gyroscope;
and (3) combining the scale factor error equations of all the functional modules to obtain the scale factor conduction model.
Optionally, the functional module includes a light source module, a coupling module, and a fiber optic loop module, and a scale factor error equation of the light source module satisfies:
wherein ,
represents the scale factor associated with said light source module, delta represents the differential operator, ++>
Indicating scale factor error associated with said light source module,/->
Representing the spontaneous emission wavelength of the light source module;
the scale factor error equation of the coupling module satisfies:
wherein ,
represents a scale factor associated with said coupling module, < >>
Representing a scale factor error, θ, associated with the coupling module 1 、θ 2 Representing the fiber coupler to shaft error;
the scale factor error equation of the fiber optic loop module satisfies:
wherein ,
indicating the scale factor associated with said fiber optic loop module,/->
Indicating the scale factor error associated with said fiber loop module, deltaT indicating the amount of temperature change,/->
Is the linear temperature expansion coefficient of the optical fiber, +.>
Indicating the wavelength of the transmitted light within the fiber optic loop.
Optionally, the coupling module includes a fiber coupler and a Y-waveguide.
Optionally, the establishing a scale factor error equation for all the functional modules results in the scale factor conduction model, including:
according to
A scale factor conduction model expression is determined.
Optionally, the scale factor conduction model expression satisfies:
optionally, the closed loop scale factor error transfer function F satisfies:
optionally, said correcting the spectrum of said initial beam according to said spectral distortion comprises:
determining a first spectrum of the initial light beam and a second spectrum transmitted by the fiber-optic gyroscope;
and feeding back the wavelength variation to a light source pumping controller according to the difference value between the first spectrum and the second spectrum, and controlling a light source to output a corrected spectrum by the light source pumping controller according to the wavelength variation.
According to another aspect of the present invention, there is provided an optical fiber gyro scale factor stability improving apparatus comprising:
the model determining module is used for determining a scale factor conduction model of the fiber-optic gyroscope;
a transfer function determining module for determining a closed loop scale factor error transfer function based on the scale factor conduction model;
the spectrum distortion determining module is used for determining the spectrum distortion of the initial light beam during the transmission of the fiber-optic gyroscope according to the closed-loop scale factor error transfer function;
and the correction module is used for correcting the spectrum of the initial light beam according to the spectrum distortion.
The embodiment of the invention provides a method and a device for improving the stability of a scale factor of an optical fiber gyroscope, which are characterized in that firstly, a scale factor conduction model of the optical fiber gyroscope is determined, then a closed-loop scale factor error transfer function is determined according to the scale factor conduction model, then the spectral distortion of an initial light beam during the transmission of the optical fiber gyroscope is determined according to the closed-loop scale factor error transfer function, and finally the spectrum of the initial light beam is corrected according to the spectral distortion. By using the method, the distortion waveform of the whole optical path of the fiber-optic gyroscope can be corrected, the correction and optimization of the waveform of the whole optical path for transmitting the light beam of the fiber-optic gyroscope can be completed, the symmetry of the waveform can be improved, and the stability of the scale factor of the ultra-high precision fiber-optic gyroscope can be improved.
It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the invention or to delineate the scope of the invention. Other features of the present invention will become apparent from the description that follows.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of a method for improving the stability of a scale factor of an optical fiber gyro according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart of another method for improving the stability of the scale factor of the fiber optic gyroscope according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of an optical fiber gyro according to an embodiment of the present invention;
FIG. 4 is a flow chart of an open loop scale factor error transfer function provided by an embodiment of the present invention;
FIG. 5 is a flow chart of a closed loop scale factor error transfer function provided by an embodiment of the present invention;
FIG. 6 is a schematic flow chart of another method for improving the stability of the scale factor of the fiber optic gyroscope according to an embodiment of the present invention;
FIG. 7 is a schematic structural diagram of another fiber optic gyroscope according to an embodiment of the present invention;
FIG. 8 is a graph showing waveform comparison before and after correction according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of waveform modification of an inverse filter output according to an embodiment of the present invention;
FIG. 10 is a schematic structural diagram of a device for improving the stability of the scale factor of an optical fiber gyroscope according to an embodiment of the present invention.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Fig. 1 is a schematic flow chart of a method for improving stability of a scale factor of an optical fiber gyro according to an embodiment of the present invention, where the method may be applied to the condition of monitoring stability of the scale factor of the optical fiber gyro, and the method may be performed by an apparatus for improving stability of the scale factor of the optical fiber gyro, where the apparatus may be implemented in a form of hardware and/or software, and where the apparatus may be configured in a control board. As shown in fig. 1, the method includes:
s110, determining a scale factor conduction model of the fiber-optic gyroscope.
The scale factor is the ratio of the output quantity and the input angular velocity of the fiber-optic gyroscope, and can be expressed by a specific linear slope on a coordinate axis, and the scale factor is an index reflecting the sensitivity of the fiber-optic gyroscope. In addition, the stability and the accuracy of the scale factors are an important index of the fiber optic gyroscope, and the testing and fitting accuracy of the fiber optic gyroscope can be comprehensively reflected. The stability of the scale factor is dimensionless and is typically expressed in parts per million (ppm). In particular, the stability of the scale factor is affected by the wavelength drift of the full optical path of the light beam transmission of the fiber optic gyroscope, which is related to the core optics of the fiber optic gyroscope. According to the light beam transmission process of the full light path of the fiber-optic gyroscope, a scale factor conduction model of the fiber-optic gyroscope is established, and the method has important significance in researching the stability of the scale factor of the fiber-optic gyroscope.
S120, determining a closed loop scale factor error transfer function according to the scale factor conduction model.
Specifically, a scale factor conduction model of the fiber-optic gyroscope is established according to the light beam transmission process of the whole light path of the fiber-optic gyroscope, the scale factor error transfer function of each part of optical devices of the whole light path is analyzed, and distortion conditions of an input waveform and an output waveform are judged in real time through the scale factor error transfer function. In addition, in order to effectively reduce the error of the scale factors and effectively improve the stability of the scale factors, a negative feedback link is introduced into the scale factor conduction model. The scale factor of the closed loop fiber-optic gyroscope is determined by the forward scale factor and the gain of the feedback channel, so that the function of stable output can be achieved, and the stability of the scale factor of the fiber-optic gyroscope is improved.
S130, according to the closed-loop scale factor error transfer function, determining the spectral distortion of the initial light beam during the transmission of the fiber-optic gyroscope.
Specifically, a negative feedback link is introduced into the scale factor conduction model, and according to a closed-loop scale factor error transfer function, the input spectrum waveform and the output spectrum waveform transmitted by the light beam are compared, so that the spectrum distortion generated when the input light beam is transmitted in the fiber-optic gyroscope conduction model is determined.
S140, correcting the spectrum of the initial light beam according to the spectrum distortion.
Specifically, the light source of the fiber-optic gyroscope conduction model emits wide-spectrum light waves, and the waveforms are distorted to a certain extent due to external disturbance after light beam transmission. The negative feedback link can correct distorted spectrum waveforms by comparing the difference value of input spectrum waveforms and output spectrum waveforms transmitted by light beams, compensate wavelength drift caused by the change of light paths along with factors such as temperature in real time, enable the subsequent output waveforms to reach ideal spectrum types, improve waveform symmetry and improve the stability of scale factors of the ultra-high-precision fiber-optic gyroscope.
According to the technical scheme, a scale factor conduction model of the optical fiber gyroscope is firstly determined, then a closed-loop scale factor error transfer function is determined according to the scale factor conduction model, then the spectrum distortion of an initial light beam during optical fiber gyroscope transmission is determined according to the closed-loop scale factor error transfer function, and finally the spectrum of the initial light beam is corrected according to the spectrum distortion. By using the method, the distortion waveform of the whole optical path of the fiber-optic gyroscope can be corrected, the correction and optimization of the waveform of the whole optical path for transmitting the light beam of the fiber-optic gyroscope can be completed, the symmetry of the waveform can be improved, and the stability of the scale factor of the ultra-high precision fiber-optic gyroscope can be improved.
Fig. 2 is a schematic flow chart of another method for improving stability of a scale factor of an optical fiber gyro according to an embodiment of the present invention, where the method is optimized based on the above embodiment, and specifically illustrates a process of determining a scale factor conduction model of the optical fiber gyro. For details not yet described in detail in this embodiment, reference is made to the above-mentioned embodiments. As shown in fig. 2, the method includes:
s210, determining a scale factor error equation of each functional module according to the light beam transmission process in the fiber-optic gyroscope.
Specifically, an input light beam of a scale factor conduction model of the fiber-optic gyroscope passes through a plurality of optical devices in the light beam transmission process, and the embodiment of the invention performs on-line test and analysis on a core optical device of the scale factor conduction model of the fiber-optic gyroscope, unifies the whole light path process of light beam transmission, analyzes a scale factor error equation of each functional module, and further unifies and compensates influence errors of each module.
The functional module comprises a light source module, a coupling module and an optical fiber ring module. Fig. 3 is a schematic structural diagram of an optical fiber gyro according to an embodiment of the present invention, as shown in fig. 3, a light beam exits from a light source module 11 and is transmitted sequentially through a coupling module 12 and an optical fiber loop module 13. Wherein the coupling module 12 comprises a fiber coupler 121 and a Y-waveguide 122. The light beam output by the optical fiber loop module 13 also needs to be transmitted to the detector 14, the detector 14 only detects the power of the output light beam, and the optical signal is converted into an electric signal, so that the subsequent waveform research is convenient, the change of the waveform cannot be influenced, and the influence of the detector 14 on the stability of the scale factor of the optical fiber gyroscope is negligible.
It should be noted that the optical fiber coupler 121 is a passive device, mainly plays roles of beam splitting and beam combining, and has a certain polarization effect, and illustratively, the optical fiber coupler 121 may be a polarization maintaining fiber, which may ensure that the direction of linear polarization is unchanged, improve the coherent signal-to-noise ratio, and meet the requirement of high-precision measurement of the scale factor. The Y-waveguide 122 acts primarily as an analyzer polarizer. However, the fusion point between the optical fiber coupler 121 and the Y-waveguide 122 has a large influence on the stability of the scale factor of the optical fiber gyro, and the optical fiber coupler 121 and the Y-waveguide 122 may be treated as a whole to form a coupling module together for simplifying the analysis process.
According to the light beam transmission process in the fiber-optic gyroscope, firstly determining a scale factor error equation of the light source module, wherein the scale factor error equation of the light source module meets the following conditions:
wherein ,
represents the scale factor associated with said light source module, delta represents the differential operator, ++>
Indicating scale factor error associated with said light source module,/->
Representing the spontaneous emission wavelength of the light source module.
Specifically, the light source body portion of the light source module may be selected to be an erbium-doped autoluminescent fluorescent light source and a high performance light source pump controller. In the actual light beam transmission process, the light beam has wavelength drift phenomenon due to the change of external temperature and other factors, so that the wavelength complementarity of a light source is poor, and the scale factor stability of the fiber-optic gyroscope can be reduced in a scale factor conduction model of the fiber-optic gyroscope.
According to the light beam transmission process in the fiber-optic gyroscope, then determining a scale factor error equation of the coupling module, wherein the scale factor error equation of the coupling module meets the following conditions:
wherein ,
represents a scale factor associated with said coupling module, < >>
Representing a scale factor error, θ, associated with the coupling module 1 、θ 2 Representing the fiber coupler axis error.
Specifically, in order to improve the scale factor stability performance of the fiber-optic gyroscope, the coupling module mainly plays roles of polarization and polarization detection. The coupling module can realize the coupling, the light splitting and the multiplexing of linearly polarized light and change the characteristic parameters of the light beam such as amplitude, intensity, frequency, phase, polarization and the like, but the coupling module is easily influenced by the change of external factors such as temperature and the like, so that the light beam has wavelength drift phenomenon, and the scale factor stability of the fiber-optic gyroscope can be reduced in a scale factor conduction model of the fiber-optic gyroscope.
According to the light beam transmission process in the fiber-optic gyroscope, finally determining a scale factor error equation of the fiber-optic loop module, wherein the scale factor error equation of the fiber-optic loop module meets the following conditions:
wherein ,
indicating the scale factor associated with said fiber optic loop module,/->
Indicating the scale factor error associated with said fiber loop module, deltaT indicating the amount of temperature change,/->
Is the linear temperature expansion coefficient of the optical fiber, +.>
Indicating the wavelength of the transmitted light within the fiber optic loop.
Specifically, in the actual light beam transmission process, the fiber optic gyroscope can work in a certain temperature range, at this time, the geometric dimension change of the fiber optic loop in the fiber optic loop module is in a certain error range, but when the external temperature of the fiber optic gyroscope changes, the geometric dimension change of the fiber optic loop can be caused, the phenomenon of wavelength drift occurs, and the scale factor stability of the fiber optic gyroscope can be reduced in a scale factor conduction model of the fiber optic gyroscope.
S220, combining the scale factor error equations of all the functional modules to obtain a scale factor conduction model.
Specifically, the scale factor of the fiber optic gyroscope is
。
Wherein L represents the fiber length of the fiber optic loop, D represents the diameter of the fiber optic loop,
the average wavelength of light is represented, and c represents the speed of light.
It should be noted that, in the light beam transmission process of the scale factor conduction model of the fiber optic gyroscope, the light source module, the coupling module and the fiber optic ring module all cause the wavelength drift phenomenon of the light beam under the influence of external factors such as temperature. Fig. 4 is a schematic flow chart of an open loop scale factor error transfer function provided by an embodiment of the present invention, as shown in fig. 4, wherein,
scale factor of input beam representing scale factor conduction model of fiber optic gyroscope, +.>
Scale factor of output beam representing scale factor conduction model of fiber optic gyroscope, +.>
Representing the output light of the light source moduleScale factor of bundle, +.>
Scale factor of the output beam of the watch coupling module, < >>
Representing the scale factor of the output beam of the fiber optic loop module.
Thus, the open loop scale factor error transfer function of the scale factor conduction model of the fiber optic gyroscope can be expressed as:
and (3) combining the scale factor error equations of all the functional modules to obtain a scale factor conduction model, wherein the expression of the scale factor conduction model meets the following conditions:
specifically, the specific expressions of the scale factor error related to the light source module, the scale factor error related to the coupling module and the scale factor error related to the optical fiber loop module are replaced by the above expressions, so that the expression of the scale factor conduction model of the optical fiber gyroscope is obtained.
It can be derived that the scale factor conduction model satisfies the expression in the open loop state:
to effectively reduce the scale factor error of the fiber optic gyroscope
The scale factor stability of the fiber-optic gyroscope is improved, and the embodiment of the invention introduces a feedback link in the scale factor conduction model of the fiber-optic gyroscope. The closed loop scale factor error transfer function of the scale factor conduction model of the fiber optic gyroscope is fed back by the scale factor error transfer function of the forward pathThe gain of the paths are jointly determined. After the negative feedback link is added, the difference value between the scale factor of the output light beam of the scale factor conduction model of the fiber-optic gyroscope and the scale factor of the input light beam of the scale factor conduction model of the fiber-optic gyroscope can be compensated into a closed loop, so that the effect of stabilizing the scale factor of the output light beam is achieved.
Specifically, the scale factor error equations of all the functional modules are combined, the connection is established between each module of the scale factor conduction model of the fiber-optic gyroscope, the unified correction of the wavelength drift phenomenon of the whole light path is realized, and the output spectrum type of the scale factor conduction model of the fiber-optic gyroscope is improved.
S230, determining a closed loop scale factor error transfer function according to the scale factor conduction model.
Specifically, fig. 5 is a schematic flow chart of a closed loop scale factor error transfer function according to an embodiment of the present invention, as shown in fig. 5, wherein,
scale factor of input beam representing scale factor conduction model of fiber optic gyroscope, +.>
Scale factor of output beam representing scale factor conduction model of fiber optic gyroscope, +.>
Scale factor representing the output beam of the light source module, < +.>
Scale factor of the output beam of the watch coupling module, < >>
Scale factor representing the output beam of the fiber optic loop module, < >>
Representing the difference between the scale factor of the input beam and the scale factor of the output beam of the scale factor conduction model of the fiber-optic gyroscope.
It can further be derived that the closed loop scale factor error transfer function F satisfies:
s240, according to the closed-loop scale factor error transfer function, determining the spectral distortion of the initial light beam during the transmission of the fiber-optic gyroscope.
S250, correcting the spectrum of the initial light beam according to the spectrum distortion.
The technical scheme of the embodiment of the invention details the determination process of the scale factor conduction model of the fiber-optic gyroscope, firstly, the scale factor error equation of each functional module is determined according to the light beam transmission process in the fiber-optic gyroscope, and then the scale factor error equations of all the functional modules are combined to obtain the scale factor conduction model. By using the method, the connection between each module of the scale factor conduction model of the fiber-optic gyroscope can be established, the wavelength drift phenomenon of the whole light path can be regulated, and the output spectrum type of the scale factor conduction model of the fiber-optic gyroscope is improved.
Fig. 6 is a flow chart of another method for improving stability of scale factor of optical fiber gyro according to the embodiment of the present invention, wherein the method is optimized based on the above embodiment, and specifically illustrates the content of the spectrum of the initial light beam corrected according to spectral distortion. For details not yet described in detail in this embodiment, reference is made to the above-mentioned embodiments. As shown in fig. 6, the method includes:
s310, determining a scale factor conduction model of the fiber-optic gyroscope.
S320, determining a closed loop scale factor error transfer function according to the scale factor conduction model.
S330, according to the closed-loop scale factor error transfer function, the spectral distortion of the initial light beam during the transmission of the fiber-optic gyroscope is determined.
S340, determining a first spectrum of the initial light beam and a second spectrum transmitted by the fiber-optic gyroscope.
Specifically, the waveform of the output light beam of the light source module of the scale factor conduction model of the optical fiber gyro is taken as a first spectrum and determined, and the waveform of the output light beam transmitted through the optical path of the scale factor conduction model of the optical fiber gyro is taken as a second spectrum and determined.
S350, feeding back the wavelength variation to the light source pumping controller according to the difference value of the first spectrum and the second spectrum, and controlling the light source to output the corrected spectrum according to the wavelength variation by the light source pumping controller.
Specifically, fig. 7 is a schematic structural diagram of another optical fiber gyro according to an embodiment of the present invention, as shown in fig. 7, in the scale factor conduction model of the optical fiber gyro, an inverse filter 15 is added between an optical fiber coupler 121 and a detector 14, where the inverse filter 15 mainly plays a role of feedback loop spectrum, and can compare the difference between the output spectrum of the light source module 11 and the output spectrum detected by the inverse filter 15, output the difference between the wavelength of the output spectrum of the light source module 11 and the wavelength of the output spectrum detected by the inverse filter 15 in real time, and then the inverse filter 15 feeds back the difference between the wavelength to a light source pump controller of the light source module 11, and the light source pump controller corrects the output spectrum according to the difference between the wavelength of the output spectrum of the light source module 11 fed back by the inverse filter 15 and the wavelength of the output spectrum detected by the inverse filter 15. In addition, a negative feedback link is added in the scale factor conduction model of the fiber-optic gyroscope, and the negative feedback link can play a role in correcting the spectrum type in real time according to the difference value between the output spectrum type of the light source module 11 and the output spectrum type detected by the inverse filter 15.
The wide spectrum light wave output by the light source module 11 sequentially passes through the coupling module 12 and the optical fiber ring module 13, in the light beam transmission process, due to the influence of external factors such as temperature, the waveform of the transmitted light beam is distorted to a certain extent, the distorted light beam is fed back to the inverse filter 15 through the coupling module, the inverse filter 15 can compare the difference value between the first spectrum and the second spectrum, then the inverse filter 15 feeds back the wavelength variation to the light source pumping controller through a negative feedback link, and the light source pumping controller can output the corrected light beam according to the wavelength variation provided by the inverse filter 15, so that the waveform of the subsequent light beam reaches an ideal output spectrum type. Fig. 8 is a schematic diagram of waveform comparison before and after correction, and as shown in fig. 8, an inverse filter 15 is used to compare the difference between the first spectrum and the second spectrum, and the light source pump controller is accurately driven by a negative feedback link, so that the corrected output waveform is closer to an ideal state, and the damage to the stability of the scale factor conduction model of the fiber optic gyroscope due to the change of external factors such as temperature is reduced.
In addition, fig. 9 is a schematic diagram of waveform correction of an output waveform of an inverse filter, and as shown in fig. 9, the minimum waveform digital resolution of the output waveform can be better than 0.01nm by correcting the output spectrum type of a scale factor conduction model of the fiber-optic gyroscope with the inverse filter, which is equivalent to 90.7ppm of stability error of the scale factor of the fiber-optic gyroscope. Illustratively, for a transmitted beam of wavelength 1530nm, a scale factor stability error of the fiber optic gyroscope of better than 7ppm can be achieved.
According to the technical scheme, the process of correcting the spectrum of the initial light beam according to the spectrum distortion is described in detail, the first spectrum of the initial light beam and the second spectrum transmitted by the optical fiber gyroscope are firstly determined, then the wavelength variation is fed back to the light source pumping controller according to the difference value between the first spectrum and the second spectrum, and the light source pumping controller controls the light source to output the corrected spectrum according to the wavelength variation. By using the method, the spectrum can be corrected according to the waveform variation, the waveform drift phenomenon in the scale factor conduction model of the fiber optic gyroscope caused by the change of external factors such as temperature can be timely dealt with, the final output light beam is corrected, and the idealization of the output spectrum type of the fiber optic gyroscope is improved. In addition, compared with the traditional wavelength compensation method only aiming at single devices such as a light source and the like, the method has the characteristic of analyzing the influence of all optical paths, including all core optical path devices such as the light source, a coupler, a Y waveguide, an optical fiber ring and the like, and the influence errors are comprehensively and uniformly compensated for the first time. The method provided by the embodiment is quick in response, and has the characteristic of compensating wavelength drift of the optical path caused by temperature and the like on line in real time by adopting a closed-loop negative feedback mechanism. Compared with the traditional off-line compensation method, the off-line compensation method has wide application range and does not need off-line compensation coefficients.
FIG. 10 is a schematic structural diagram of a device for improving stability of scale factors of fiber optic gyroscope according to an embodiment of the present invention, where the device may be implemented in hardware and/or software and is generally configured in a control board. As shown in fig. 10, the apparatus includes:
a model determination module 21 for determining a scale factor conduction model of the fiber optic gyroscope; a transfer function determination module 22 for determining a closed loop scale factor error transfer function from the scale factor conduction model; the spectral distortion determining module 23 is used for determining the spectral distortion of the initial light beam during the transmission of the fiber-optic gyroscope according to the closed-loop scale factor error transfer function; a correction module 24 for correcting the spectrum of the initial beam according to the spectral distortion.
According to the technical scheme, a scale factor conduction model of the optical fiber gyroscope is firstly determined, then a closed-loop scale factor error transfer function is determined according to the scale factor conduction model, then the spectrum distortion of an initial light beam during optical fiber gyroscope transmission is determined according to the closed-loop scale factor error transfer function, and finally the spectrum of the initial light beam is corrected according to the spectrum distortion. By using the method, the distortion waveform of the whole optical path of the fiber-optic gyroscope can be corrected, the correction and optimization of the waveform of the whole optical path for transmitting the light beam of the fiber-optic gyroscope can be completed, the symmetry of the waveform can be improved, and the stability of the scale factor of the ultra-high precision fiber-optic gyroscope can be improved.
Alternatively, the model determining module 21 may specifically include an error equation determining unit for determining a scale factor error equation of each functional module according to the beam transmission process in the fiber optic gyroscope, and an error equation co-ordinating unit for co-ordinating the scale factor error equations of all the functional modules to obtain the scale factor conduction model.
Optionally, the correction module 24 may specifically include a spectrum determining unit and a feedback correction unit, where the spectrum determining unit is configured to determine a first spectrum of the initial light beam and a second spectrum transmitted by the fiber optic gyroscope, and the feedback correction unit is configured to feed back a wavelength variation to the optical pump controller according to a difference between the first spectrum and the second spectrum, and the optical pump controller controls the optical source to output the corrected spectrum according to the wavelength variation.
The device for improving the stability of the scale factors of the fiber-optic gyroscope provided by the embodiment of the invention can execute the method for improving the stability of the scale factors of the fiber-optic gyroscope provided by any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the execution method.
The above embodiments do not limit the scope of the present invention. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.
Claims (7)
1. The method for improving the stability of the scale factor of the fiber-optic gyroscope is characterized by comprising the following steps of:
determining a scale factor conduction model of the fiber-optic gyroscope;
determining a closed loop scale factor error transfer function from the scale factor conduction model;
according to the closed loop scale factor error transfer function, determining the spectral distortion of an initial light beam during the transmission of the fiber-optic gyroscope;
correcting the spectrum of the initial beam according to the spectral distortion;
wherein, the determining the scale factor conduction model of the fiber optic gyroscope comprises:
determining a scale factor error equation of each functional module according to the light beam transmission process in the fiber-optic gyroscope;
establishing a scale factor error equation of all the functional modules simultaneously to obtain a scale factor conduction model;
the functional module comprises a light source module, a coupling module and an optical fiber ring module, and the scale factor error equation of the light source module meets the following conditions:
wherein ,
represents the scale factor associated with said light source module, delta represents the differential operator, ++>
Indicating scale factor error associated with said light source module,/->
Representing the spontaneous emission wavelength of the light source module;
the scale factor error equation of the coupling module satisfies:
wherein ,
represents a scale factor associated with said coupling module, < >>
Representing a scale factor error, θ, associated with the coupling module 1 、θ 2 Representing the fiber coupler to shaft error;
the scale factor error equation of the fiber optic loop module satisfies:
wherein ,
indicating the scale factor associated with said fiber optic loop module,/->
Indicating the scale factor error associated with said fiber loop module, deltaT indicating the amount of temperature change,/->
Is the linear temperature expansion coefficient of the optical fiber, +.>
Indicating the wavelength of the transmitted light within the fiber optic loop.
2. The method of claim 1, wherein the coupling module comprises a fiber coupler and a Y-waveguide.
3. The method of claim 1, wherein the establishing the scale factor error equations for all of the functional blocks to obtain the scale factor conduction model comprises:
according to
A scale factor conduction model expression is determined.
4. A method of improving the stability of a scale factor of a fiber optic gyroscope according to claim 3, wherein the scale factor conduction model expression satisfies:
5. the method of claim 4, wherein the closed loop scale factor error transfer function F satisfies:
6. the method of claim 1, wherein said correcting the spectrum of the initial light beam according to the spectral distortion comprises:
determining a first spectrum of the initial light beam and a second spectrum transmitted by the fiber-optic gyroscope;
and feeding back the wavelength variation to a light source pumping controller according to the difference value between the first spectrum and the second spectrum, and controlling a light source to output a corrected spectrum by the light source pumping controller according to the wavelength variation.
7. A fiber optic gyroscope scale factor stability enhancement device, comprising:
the model determining module is used for determining a scale factor conduction model of the fiber-optic gyroscope;
a transfer function determining module for determining a closed loop scale factor error transfer function based on the scale factor conduction model;
the spectrum distortion determining module is used for determining the spectrum distortion of the initial light beam during the transmission of the fiber-optic gyroscope according to the closed-loop scale factor error transfer function;
the correction module is used for correcting the spectrum of the initial light beam according to the spectrum distortion;
the model determining module comprises an error equation determining unit and an error equation combining unit, wherein the error equation determining unit is used for determining the scale factor error equation of each functional module according to the light beam transmission process in the fiber-optic gyroscope, and the error equation combining unit is used for combining the scale factor error equations of all the functional modules to obtain the scale factor conduction model.
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