CN121761855A - Precision maintaining method based on adaptive adjustment of modulation depth of fiber-optic gyroscope - Google Patents
Precision maintaining method based on adaptive adjustment of modulation depth of fiber-optic gyroscopeInfo
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Abstract
本发明提供了一种基于光纤陀螺调制深度自适应调整的精度保持方法，属于光纤陀螺调制技术领域，解决了现有技术难以自适应地调整调制深度的问题。该方法包括：构建最佳调制深度与台阶高度之间的关系；获取光纤陀螺光路系统实时输出的光干涉信号，根据所述最佳调制深度与台阶高度之间的关系，确定当前光功率的最佳调制深度；基于光功率的最佳调制深度和附加调制信号，生成模拟调制信号；将模拟调制信号输入光纤陀螺光路系统，实现对光纤陀螺的精度保持控制。
This invention provides a precision maintenance method based on adaptive adjustment of the modulation depth of a fiber optic gyroscope, belonging to the field of fiber optic gyroscope modulation technology, and solves the problem of existing technologies' difficulty in adaptively adjusting the modulation depth. The method includes: establishing a relationship between the optimal modulation depth and the step height; acquiring the optical interference signal output in real time by the fiber optic gyroscope optical path system; determining the optimal modulation depth for the current optical power based on the relationship between the optimal modulation depth and the step height; generating an analog modulation signal based on the optimal modulation depth of the optical power and the additional modulation signal; and inputting the analog modulation signal into the fiber optic gyroscope optical path system to achieve precision maintenance control of the fiber optic gyroscope.
Description
Technical Field
The invention relates to the technical field of optical fiber gyro modulation, in particular to a precision maintaining method based on adaptive adjustment of optical fiber gyro modulation depth.
Background
The optical fiber gyro is used as a high-precision inertial sensor, and the precision of the optical fiber gyro mainly depends on the stability of optical power in an optical path system of the optical fiber gyro. In practical application, the optical path system of the fiber-optic gyroscope is affected by various factors, such as temperature change, fiber aging, light source power fluctuation and the like, which can cause the change of the light power, and finally reduce the precision performance of the fiber-optic gyroscope.
Most of the traditional optical fiber gyro modulation depth adjustment methods are based on fixed parameters, and cannot adapt to dynamic changes of optical power in real time. For example, in some fiber optic gyro systems, the modulation depth is preset, and once the optical power is changed, the matching relationship between the modulation depth and the optical power is broken, resulting in the degradation of the accuracy of the fiber optic gyro. In addition, although the modulation depth can be adjusted to a certain extent, the adjustment process is complex, the real-time performance is poor, and the precision maintaining requirement of the high-precision fiber-optic gyroscope in a dynamic environment is difficult to meet.
Therefore, how to adaptively adjust the modulation depth according to the optical interference signal output by the optical path system of the fiber-optic gyroscope in real time so as to maintain the measurement accuracy of the fiber-optic gyroscope is a technical problem to be solved in the technical field of the fiber-optic gyroscope at present.
Disclosure of Invention
In view of the above analysis, the embodiment of the invention aims to provide a precision maintaining method based on adaptive adjustment of modulation depth of an optical fiber gyroscope, which is used for solving the problem that the modulation depth is difficult to adjust adaptively in the prior art.
The invention provides a precision maintaining method based on adaptive adjustment of modulation depth of an optical fiber gyroscope, which comprises the following steps:
Constructing a relation between the optimal modulation depth and the step height;
Acquiring an optical interference signal output by an optical fiber gyro optical path system in real time, and determining the optimal modulation depth of the current optical power according to the relation between the optimal modulation depth and the step height;
generating an analog modulation signal based on the optimal modulation depth of the current optical power and the additional modulation signal;
and inputting the analog modulation signal into a fiber optic gyroscope optical path system to realize the precision maintenance control of the fiber optic gyroscope.
Based on the scheme, the invention also makes the following improvements:
Further, the constructing the relation between the optimal modulation depth and the step height is performed by:
constructing a curve relation between the optical power and the optimal modulation depth of the fiber-optic gyroscope;
And constructing the relation between the optimal modulation depth and the step height according to the curve relation between the optical power of the optical fiber gyroscope and the optimal modulation depth.
Further, a curve relation between the optical power and the optimal modulation depth of the fiber-optic gyroscope is constructed, and the following steps are executed:
Setting a plurality of optical power points at fixed power intervals; setting a plurality of modulation depths at fixed modulation depth intervals at each optical power point;
For each optical power point, calculating RWC corresponding to each modulation depth under the current optical power point, and taking the modulation depth when the RWC takes the minimum value as the optimal modulation depth corresponding to the current optical power point;
Fitting the relation between the optical power and the optimal modulation depth according to each optical power point and the corresponding optimal modulation depth, and establishing a curve relation between the optical power and the optimal modulation depth.
Further, a binary first-order equation is selected to fit the relation between the optical power and the optimal modulation depth, a second-order fitting parameter a 0、a1、a2 is determined in the fitting process, and a second-order fitting curve relation between the optical power and the optimal modulation depth is established, wherein the relation is expressed as follows:
Φ0i＝a0+a1P0i+a2P0i 2 (3)
Where P 0i denotes an optical power, Φ 0i denotes an optimal modulation depth corresponding to the current optical power.
Further, the relationship between the optimal modulation depth and the step height is expressed as:
Φ0i＝b0+b1ΔCi+b2ΔCi 2 (1)
Where Δc i denotes a step height, Φ 0i denotes an optimal modulation depth, and b 0＝a0,b1＝a1/K,b2＝a2/K,K＝P0i/ΔCi.
Further, the method determines the optimal modulation depth of the current optical power according to the relation between the optimal modulation depth and the step height, and executes:
performing signal amplification and analog-to-digital conversion on the optical interference signal to generate a digital interference signal;
Decomposing the digital interference signal into a rate signal to be demodulated and an optical power signal to be demodulated;
And obtaining the optimal modulation depth corresponding to the current optical power according to the relation between the optimal modulation depth and the step height.
Further, the generating of the analog modulation signal performs:
generating a step wave signal according to the rate signal to be demodulated;
generating a corresponding normal modulation signal according to the optimal modulation depth;
superposing the generated step wave signal, the normal modulation signal and the additional modulation signal to obtain a digital modulation signal;
Digital-to-analog conversion and signal amplification are performed on the digital modulation signal to generate an analog modulation signal.
Further, the period of the additional modulation signal is 2nτ, wherein,
Τ is the transit time of the fiber optic gyroscope, and N is a positive integer;
the duration of the additional interference signal is 2τ during one period of the additional modulation signal.
Further, demodulating the optical power signal to be demodulated to obtain a demodulation amount of the optical power, and executing:
demodulating a digital signal amplitude C1 when an additional interference signal exists and a digital signal amplitude C2 when the additional interference signal does not exist from the optical power signal to be demodulated;
The step height Δc=c1-C2 is calculated according to the formula, and the step height Δc is taken as the demodulation amount of the optical power.
Further, the step wave signal is generated according to the rate signal to be demodulated, and the steps are executed:
Performing rate demodulation on the rate signal to be demodulated to generate a closed loop feedback step signal corresponding to the rate information of the rate signal to be demodulated;
and integrating the closed loop feedback step signal to generate a step wave signal.
Compared with the prior art, the invention has at least one of the following beneficial effects:
The application provides a precision maintaining method based on adaptive adjustment of the modulation depth of an optical fiber gyroscope, which has the following technical effects:
(1) Improving the measurement accuracy of the fiber optic gyroscope
By constructing the relation between the optimal modulation depth and the step height and the curve relation between the optical power and the optimal modulation depth, the optimal modulation depth of the current optical power can be accurately determined according to the optical interference signal output by the optical fiber gyro optical path system in real time. The self-adaptive adjustment mode enables the optical fiber gyro to adjust the modulation depth in time when the optical power changes, so that the measurement accuracy is kept, and the problem of accuracy reduction caused by mismatching of the modulation depth and the optical power is effectively avoided.
(2) Enhancing adaptability of fiber optic gyroscopes
The method can monitor the optical power change of the optical path system of the fiber optic gyroscope in real time and quickly adjust the corresponding modulation depth, so that the method can adapt to various complex dynamic environments such as temperature change, fiber optic aging and the like. The self-adaptive capacity greatly enhances the stability and reliability of the fiber-optic gyroscope in different application scenes, and improves the performance of the fiber-optic gyroscope in practical application.
(3) Simplifying modulation depth adjustment process
The method adopts a series of efficient signal processing and calculating steps, such as signal amplification and analog-to-digital conversion of the optical interference signal, digital interference signal decomposition, optical power signal demodulation and the like, and can rapidly and accurately determine the optimal modulation depth and generate corresponding analog modulation signals. Compared with the traditional modulation depth adjusting method, the adjusting process of the method is simpler and quicker, and the overall operation efficiency of the fiber-optic gyroscope system is improved.
(4) Reducing errors in fiber optic gyroscopes
By precisely calculating the step height and determining the optimal modulation depth from the relationship between the step height and the optimal modulation depth, random walk error (RWC) of the fiber-optic gyroscope can be effectively reduced. And setting a plurality of modulation depths at fixed modulation depth intervals under each optical power point, calculating RWC corresponding to each modulation depth, and taking the modulation depth when the RWC takes the minimum value as the optimal modulation depth corresponding to the current optical power point.
In the invention, the technical schemes can be mutually combined to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, like reference numerals being used to designate like parts throughout the drawings;
FIG. 1 is a flowchart of a precision maintaining method based on adaptive adjustment of modulation depth of an optical fiber gyro according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a quadratic fit curve relationship between optical power and optimal modulation depth according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a modem system for maintaining accuracy of an optical fiber gyro according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a step wave modulated signal, a normal modulated signal, and an additional modulated signal according to an embodiment of the present invention;
Fig. 5 is a schematic diagram of an optical power signal to be demodulated according to an embodiment of the present invention;
The reference sign is 1-fiber optic gyro optical subsystem, 2-front stage amplifying and analog-to-digital converting circuit, 3-demodulation information classifying module, 4-rate information demodulating module, 5-ladder wave signal generator, 6-optical power information demodulating module, 7-modulation depth adjusting module, 8-normal modulation signal generating module, 9-additional modulation signal generating module, 10-modulation signal combining module and 11-digital-to-analog converting and rear stage amplifying circuit.
Detailed Description
The following detailed description of preferred embodiments of the application is made in connection with the accompanying drawings, which form a part hereof, and together with the description of the embodiments of the application, are used to explain the principles of the application and are not intended to limit the scope of the application.
In one embodiment of the invention, a precision maintaining method based on adaptive adjustment of modulation depth of a fiber-optic gyroscope is disclosed, and a flow chart of the method is shown in fig. 1 and specifically described as follows.
And S1, constructing the relation between the optimal modulation depth and the step height.
And S11, constructing a curve relation between the optical power and the optimal modulation depth of the fiber-optic gyroscope.
Step S111, a plurality of optical power points are set at fixed power intervals, and a plurality of modulation depths are set at fixed modulation depth intervals under each optical power point. For example, for a certain optical power point, the modulation depth is set to pi/2 in order.
In the implementation process, the modulation depth interval corresponds to the resolution of the digital-to-analog converter, and, for example, if the digital-to-analog converter bit number is M, the minimum interval ΔΦ 0 of the modulation depth is determined by equation (2):
Step S112, for each optical power point, calculating RWC corresponding to each modulation depth under the current optical power point (using the fiber optic gyro RWC calculation formula in formula (1)), and taking the modulation depth when the RWC takes the minimum value as the optimal modulation depth corresponding to the current optical power point.
And step S1113, fitting the relation between the optical power and the optimal modulation depth according to each optical power point and the optimal modulation depth corresponding to each optical power point, and establishing a curve relation between the optical power and the optimal modulation depth.
Illustratively, in this embodiment, a binary first-order equation is selected to fit the relationship between the two, and in the fitting process, a second-order fitting parameter a 0、a1、a2 is determined, so as to establish a second-order fitting curve relationship between the optical power and the optimal modulation depth, which is expressed as:
Φ0i＝a0+a1P0i+a2P0i 2 (3)
Where P 0i denotes an optical power, Φ 0i denotes an optimal modulation depth corresponding to the current optical power.
A schematic of the quadratic fit curve relationship between optical power and optimal modulation depth is shown in fig. 2. According to the embodiment, the real-time adjustment of the optimal modulation depth can be realized by establishing the quadratic fit curve relationship between the optical power and the optimal modulation depth, so that the precision is kept.
And S12, constructing a relation between the optimal modulation depth and the step height according to a curve relation between the optical power of the fiber-optic gyroscope and the optimal modulation depth.
The step height is proportional to the optical power amplitude, and therefore the relationship between the optimal modulation depth and the step height is expressed as:
Φ0i＝b0+b1ΔCi+b2ΔCi 2 (4)
wherein ΔC i represents the step height, b 0＝a0,b1＝a1/K,b2＝a2/K,K＝P0i/ΔCi.
And S2, acquiring an optical interference signal output by the optical fiber gyro optical path system in real time, and determining the optimal modulation depth of the current optical power according to the relation between the optimal modulation depth and the step height.
Next, the specific implementation procedure of step S2 is described as follows.
And S21, performing signal amplification and analog-to-digital conversion on the optical interference signal to generate a digital interference signal.
And S22, decomposing the digital interference signal into a rate signal to be demodulated and an optical power signal to be demodulated.
And S23, carrying out additional interference demodulation on the optical power signal to be demodulated to obtain the demodulation quantity of the optical power, and obtaining the optimal modulation depth corresponding to the current optical power according to the relation between the optimal modulation depth and the step height.
And S3, generating an analog modulation signal based on the optimal modulation depth of the optical power and the additional modulation signal.
And S31, carrying out rate demodulation on the rate signal to be demodulated to generate a closed-loop feedback step signal corresponding to the rate information of the rate signal to be demodulated, and integrating the closed-loop feedback step signal to generate a step wave signal.
And S32, generating a corresponding normal modulation signal according to the optimal modulation depth.
And S33, superposing the generated step wave signal, the normal modulation signal and the additional modulation signal to obtain a digital modulation signal.
And step S34, digital-to-analog conversion and signal amplification are carried out on the digital modulation signal to generate an analog modulation signal.
And S4, inputting the analog modulation signal into a fiber optic gyroscope optical path system to realize the precision maintenance control of the fiber optic gyroscope.
The embodiment 2 of the invention also discloses a modulation and demodulation system for realizing the precision maintenance of the fiber-optic gyroscope, which is realized based on the precision maintenance method based on the adaptive adjustment of the modulation depth of the fiber-optic gyroscope in the embodiment 1. A schematic of the system is shown in fig. 3. The modulation and demodulation system comprises a fiber-optic gyroscope optical subsystem, a signal processing and converting subsystem and a modulation and demodulation subsystem. The following describes each subsystem in detail.
(1) Optical fiber gyro optical subsystem
The optical path subsystem of the fiber-optic gyroscope (i.e. the optical path system of the fiber-optic gyroscope in embodiment 1) is used for outputting optical interference signals to the signal processing and converting subsystem in real time, and is also used for receiving analog modulation signals output by the modulation and demodulation subsystem in real time and carrying out real-time phase modulation on the fiber-optic gyroscope.
In this embodiment, the fiber-optic gyro optical subsystem is composed of a light source, a coupler, a fiber-optic ring, an integrated optical modulator and a photodetector, and can realize the Sagnac effect of the fiber-optic gyro.
In particular operation, the light source produces a stable optical signal that is the basis for subsequent interference and modulation. The coupler splits the optical signal into two beams that propagate in the clockwise and counterclockwise directions of the fiber optic ring, respectively. When the optical fiber ring rotates, the two light signals generate optical path difference due to rotation, so that a Sagnac phase difference is formed, and the Sagnac phase difference is a core representation of the Sagnac effect. The integrated optical modulator carries out real-time phase modulation on the two light signals according to the received analog modulation signals, and the modulation signals are overlapped with Sagnac phase differences so as to facilitate subsequent signal processing. The two modulated optical signals interfere at the coupler, and the intensity change of the interference signals reflects the combined effect of the Sagnac phase difference and the modulation phase. The photodetector converts the interference light signal into an electrical signal, and outputs an optical power signal (i.e., an interference signal) related to the interference intensity, which contains information of the Sagnac effect, for subsequent demodulation and calculation of the rotational angular velocity. From the above, the optical interference signal is output from the photodetector, and the analog modulation signal is applied to the integrated optical modulator.
(2) Signal processing and conversion subsystem
And the signal processing and converting subsystem is used for performing signal processing on the interference signals, generating digital interference signals and inputting the digital interference signals into the modulation and demodulation subsystem.
Specifically, in the present embodiment, the signal processing and converting subsystem may be implemented by using the pre-amplifying and analog-to-digital converting circuit 2.
The pre-amplifying and analog-to-digital converting circuit 2 is used for amplifying and analog-to-digital converting the optical interference signal (i.e. the electric signal converted by the photoelectric detector) to generate a digital interference signal, and inputting the digital interference signal into the demodulation information classifying module in the modulation and demodulation subsystem.
(3) Modulation and demodulation subsystem
The modulation and demodulation subsystem is used for carrying out rate demodulation and additional interference demodulation according to the digital interference signals, carrying out superposition on the rate demodulation to obtain a step wave signal, the normal modulation signal obtained by the additional interference demodulation and the additional modulation signal to obtain a digital modulation signal, and carrying out signal processing on the digital modulation signal to generate the analog modulation signal.
The modulation and demodulation subsystem comprises a demodulation information classification module 3, a rate information demodulation module 4, a step wave signal generator 5, an optical power information demodulation module 6, a modulation depth adjustment module 7, a normal modulation signal generation module 8, an additional modulation signal generation module 9, a modulation signal combination module 10 and a digital-to-analog conversion and post-amplification circuit 11. The functions of the respective components are specifically described below.
1) Demodulation information classification module 3
The demodulation information classification module 3 is configured to decompose the digital interference signal into a rate signal to be demodulated and an optical power signal to be demodulated, and input the rate signal to be demodulated and the optical power signal to be demodulated into the rate information demodulation module 4 and the optical power information demodulation module 6 respectively.
In the specific implementation process, the demodulation information classification module 3 can decompose the digital interference signal according to a preset control time sequence.
2) Rate information demodulation module 4
The rate information demodulation module 4 is used for performing rate demodulation on the rate signal to be demodulated, generating a closed-loop feedback step signal corresponding to the rate information of the rate signal to be demodulated, and inputting the closed-loop feedback step signal into the step wave signal generation module 5.
In the implementation process, the signal to be demodulated can be demodulated according to the demodulation time sequence.
3) Step wave signal generating module 5
The step wave signal generating module 5 is configured to integrate the closed loop feedback step signal to generate a step wave signal.
4) Optical power information demodulation module 6
The optical power information demodulation module 6 is used for carrying out additional interference demodulation on the optical power signal to be demodulated to obtain the demodulation quantity of the optical power, and inputting the demodulation quantity of the optical power into the modulation depth adjustment module 7.
Specifically, the optical power information demodulation module 6 demodulates the optical power signal to be demodulated, and performs demodulation of the digital signal amplitude C1 when the additional interference signal is present and the digital signal amplitude C2 when the additional interference signal is absent from the optical power signal to be demodulated, calculates the step height Δc=c1-C2 according to a formula, and uses the step height Δc as the demodulation amount of the optical power. The processing means will be further described herein with reference to fig. 2 and 3.
In the specific implementation process, the demodulation information classification module 3 extracts the optical power signal to be demodulated according to the application time sequence of the additional modulation signal, and sends the optical power signal to the optical power information demodulation module 6.
5) Modulation depth adjustment module 7
The modulation depth adjusting module 7 is configured to determine an optimal modulation depth corresponding to the current optical power according to the demodulation amount of the optical power, and input the optimal modulation depth into the normal modulation signal generating module 8.
In a specific implementation process, according to the relationship between the pre-established step height Δc (i.e. the demodulation amount of the optical power signal to be demodulated) and the optimal modulation depth (digital amount), the embodiment can obtain the optimal modulation depth corresponding to the current optical power, i.e. the optimal modulation depth corresponding to the modulation signal to be applied, according to the demodulation amount of the optical power signal to be demodulated, so that the precision of the fiber-optic gyroscope is optimal.
6) Normal modulation signal generation module 8
The normal modulation signal generation module 8 is configured to generate a corresponding normal modulation signal according to the optimal modulation depth.
In some embodiments, the gyro normal modulation mode generated by the normal modulation signal generation module 8 may be a four-state modulation mode, a square wave modulation mode or a hybrid modulation mode. And taking the optimal modulation depth as the modulation phase of the normal modulation signal, and generating a corresponding normal modulation signal according to the gyro normal modulation mode.
The normal modulation signal generation module 8 receives the optimal modulation depth output by the modulation depth adjustment module 7 and changes the current gyro modulation depth into the optimal modulation depth, so that modulation phase adjustment of the fiber-optic gyro is realized, and the accuracy of the gyro is optimized.
7) Additional modulation signal generating module 9
The additional modulation signal generation module 9 is configured to periodically output an additional modulation signal.
In this embodiment, the period of the additional modulation signal is 2nτ, where τ is the transit time of the fiber-optic gyroscope and N is a positive integer. Since the change in optical power is a very slow process, the value of N can be very large.
In one period of the additional modulation signal, the duration of the additional interference signal is 2τ, the amplitude of the additional interference signal in the first τ is pi/M, the amplitude of the additional interference signal in the second τ is-pi/M, and M is a positive integer.
8) Modulation signal combination module 10
The modulation signal combination module 10 is configured to superimpose the step wave signal, the normal modulation signal and the additional modulation signal, and generate a digital modulation signal.
In the specific implementation process, the step wave signal output by the step wave signal generating module 5, the normal modulation signal output by the normal modulation signal generating module 8 and the additional modulation signal generated by the additional modulation signal generating module 9 are synchronously overlapped in the modulation signal combining module 10 by taking the transition time tau as a period.
The modulation mode has the advantages that the modulation signals required by the normal operation of the fiber-optic gyroscope, namely the normal modulation signal and the step wave signal, are combined, and additional modulation signals for maintaining the precision can be considered. The modulation mode can not influence the normal operation of the fiber-optic gyroscope, and simultaneously generates the optical power to be demodulated brought by the additional modulation signal at the demodulation end, so as to realize the demodulation of the optical power.
The periodic additional modulation signal can enable the integrated optical modulator to generate periodic additional phase modulation, the modulation phase can act on the optical interference signal of the optical subsystem of the fiber-optic gyroscope, and the periodic additional step digital signal (namely, the optical power signal to be demodulated) is generated through the pre-amplifying and analog-digital conversion circuit 2.
9) Post-amplification and digital-to-analog conversion circuit 11
The post-amplification and digital-to-analog conversion circuit 11 is used for performing digital-to-analog conversion and signal amplification on the digital modulation signal to generate a corresponding analog modulation signal.
And inputting the analog modulation signal to an integrated optical modulator in the optical path subsystem of the fiber-optic gyroscope to realize the phase modulation of the fiber-optic gyroscope.
According to the embodiment, through the modulation and demodulation mode, the condition of the optical power change of the gyroscope is monitored in real time finally, the modulation depth of the gyroscope is adjusted on line according to the optical power change, the precision of the fiber-optic gyroscope is kept at the optimal value under the current optical power, and the precision of the fiber-optic gyroscope is kept.
In this embodiment, the generated digital modulation signal can realize rate information demodulation output and modulation phase feedback generation.
Fig. 4 is a schematic diagram of a step wave modulated signal, a normal modulated signal, and an additional modulated signal.
Fig. 5 is a schematic diagram of an optical power signal to be demodulated.
In this embodiment, the demodulation amount of the optical power is the step height Δc in fig. 5. The additional modulated signal carries a periodic additional interference signal (i.e. additional step digital information) with a step height deltac proportional to the current optical power amplitude. The digital signal amplitude is C1 when no additional interference signal exists, and C2 when the additional interference signal exists. Referring to fig. 5, B1 is partially a response signal generated due to the application of the additional modulation signal shown in fig. 4, the combination of B1 and a is an optical power signal to be demodulated, and the combination of B and a is a rate signal to be demodulated. When the additional modulation signal shown in fig. 4 is applied, the signals A1 and B1 in fig. 5 are necessarily generated, that is, the optical power signal to be demodulated is generated. In the demodulation process of the optical power information demodulation module 6, a method of corresponding subtraction of signals in two adjacent demodulation periods is adopted, the digital signal amplitude is C1 when no additional interference signal exists, the digital signal amplitude is C2 when the additional interference signal exists, and the step height delta C is obtained by subtracting the two signals.
Based on the above description, the method for maintaining precision based on adaptive adjustment of modulation depth of optical fiber gyroscope according to the present embodiment mainly includes:
1. The method has the core innovation points that based on real-time detection of the change of the optical power of the fiber-optic gyroscope, the optimal modulation depth is calculated and timely adjusted in the gyroscope through a software algorithm by adopting the established fitting function relation of the optical power and the modulation depth, so that the gyroscope precision is always kept at the optimal precision level corresponding to the current optical power. The whole implementation process does not need to change the hardware states of a gyro light path, a circuit and the like, and is easy to realize and popularize.
2. The secondary innovation point 1 is that an additional interference signal is formed by an additional modulation method with the duration of 2τ and the signal amplitude of + -pi/M (M is a positive integer), and the real-time monitoring of the change of the optical power of the gyroscope is realized by a demodulation method corresponding to the time sequence of the modulation signal.
3. The secondary innovation point 2 is that a fitting method of the optical power and the optimal modulation depth of the fiber-optic gyroscope is established based on a calculation method of the fiber-optic gyroscope RWC, and the method is convenient to realize in a software algorithm chip FPGA used by the mainstream fiber-optic gyroscope;
4. The minor innovation point 3 is that the scheme has higher adjustment precision on the modulation depth and can reach N is the digital to analog converter bit number.
According to the embodiment, the period of the additional modulation signal is set to be 2N tau, and the optical power signal to be demodulated and the rapid demodulation and processing of the rate signal are realized, so that the optical fiber gyroscope can rapidly respond to the change of the optical power and the rate, and the dynamic performance of the optical fiber gyroscope is improved. The quick response capability is important for maintaining high-precision measurement of the fiber optic gyroscope in a high-speed moving or quick-changing environment, can better meet the requirement of a modern navigation system on the dynamic performance of the fiber optic gyroscope, and effectively improves the dynamic performance of the fiber optic gyroscope.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.
Claims (10)
1. The method for maintaining the precision based on the adaptive adjustment of the modulation depth of the fiber-optic gyroscope is characterized by comprising the following steps:
Constructing a relation between the optimal modulation depth and the step height;
Acquiring an optical interference signal output by an optical fiber gyro optical path system in real time, and determining the optimal modulation depth of the current optical power according to the relation between the optimal modulation depth and the step height;
generating an analog modulation signal based on the optimal modulation depth of the current optical power and the additional modulation signal;
and inputting the analog modulation signal into a fiber optic gyroscope optical path system to realize the precision maintenance control of the fiber optic gyroscope.
2. The method for maintaining precision based on adaptive adjustment of modulation depth of fiber-optic gyroscope according to claim 1, wherein the constructing the relation between the optimal modulation depth and the step height is performed by:
constructing a curve relation between the optical power and the optimal modulation depth of the fiber-optic gyroscope;
And constructing the relation between the optimal modulation depth and the step height according to the curve relation between the optical power of the optical fiber gyroscope and the optimal modulation depth.
3. The method for maintaining precision based on adaptive adjustment of modulation depth of optical fiber gyro according to claim 2, wherein constructing a curve relationship between optical power and optimal modulation depth of the optical fiber gyro, performing:
Setting a plurality of optical power points at fixed power intervals; setting a plurality of modulation depths at fixed modulation depth intervals at each optical power point;
For each optical power point, calculating RWC corresponding to each modulation depth under the current optical power point, and taking the modulation depth when the RWC takes the minimum value as the optimal modulation depth corresponding to the current optical power point;
Fitting the relation between the optical power and the optimal modulation depth according to each optical power point and the corresponding optimal modulation depth, and establishing a curve relation between the optical power and the optimal modulation depth.
4. The method for maintaining precision based on adaptive adjustment of modulation depth of fiber optic gyroscope according to claim 3, wherein a binary first-order equation is selected to fit the relationship between the optical power and the optimal modulation depth, a second-order fitting parameter a 0、a1、a2 is determined during the fitting process, and a second-order fitting curve relationship between the optical power and the optimal modulation depth is established, which is expressed as:
Φ0i＝a0+a1P0i+a2P0i 2 (3)
Where P 0i denotes an optical power, Φ 0i denotes an optimal modulation depth corresponding to the current optical power.
5. The method for maintaining precision based on adaptive adjustment of modulation depth of optical fiber gyro according to claim 4, wherein the relation between the optimal modulation depth and the step height is expressed as:
Φ0i＝b0+b1ΔCi+b2ΔCi 2 (1)
Where Δc i denotes a step height, Φ 0i denotes an optimal modulation depth, and b 0＝a0,b1＝a1/K,b2＝a2/K,K＝P0i/ΔCi.
6. The method for maintaining precision based on adaptive adjustment of modulation depth of optical fiber gyro according to any one of claims 1 to 5, wherein the determining of the optimal modulation depth of the current optical power according to the relation between the optimal modulation depth and the step height is performed by:
performing signal amplification and analog-to-digital conversion on the optical interference signal to generate a digital interference signal;
Decomposing the digital interference signal into a rate signal to be demodulated and an optical power signal to be demodulated;
And obtaining the optimal modulation depth corresponding to the current optical power according to the relation between the optimal modulation depth and the step height.
7. The method for maintaining precision based on adaptive adjustment of modulation depth of fiber-optic gyroscope according to claim 6, wherein the generating of the analog modulation signal is performed by:
generating a step wave signal according to the rate signal to be demodulated;
generating a corresponding normal modulation signal according to the optimal modulation depth;
superposing the generated step wave signal, the normal modulation signal and the additional modulation signal to obtain a digital modulation signal;
Digital-to-analog conversion and signal amplification are performed on the digital modulation signal to generate an analog modulation signal.
8. The method for maintaining precision based on adaptive adjustment of modulation depth of optical fiber gyro according to claim 7, wherein the period of the additional modulation signal is 2nτ, wherein,
Τ is the transit time of the fiber optic gyroscope, and N is a positive integer;
the duration of the additional interference signal is 2τ during one period of the additional modulation signal.
9. The method for maintaining precision based on adaptive adjustment of modulation depth of optical fiber gyro according to claim 8, wherein demodulating the power signal to be demodulated to obtain the demodulation amount of the optical power, performs:
demodulating a digital signal amplitude C1 when an additional interference signal exists and a digital signal amplitude C2 when the additional interference signal does not exist from the optical power signal to be demodulated;
The step height Δc=c1-C2 is calculated according to the formula, and the step height Δc is taken as the demodulation amount of the optical power.
10. The method for maintaining precision based on adaptive adjustment of modulation depth of optical fiber gyro according to claim 9, wherein the step wave signal is generated according to the rate signal to be demodulated, and the steps of:
Performing rate demodulation on the rate signal to be demodulated to generate a closed loop feedback step signal corresponding to the rate information of the rate signal to be demodulated;
and integrating the closed loop feedback step signal to generate a step wave signal.
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