A Closed-Loop Compensation Method for Suppressing the Wavelength Dependence of the Scale Factor of Fiber Optic Gyros

Abstract

The present invention belongs to the technical field of fiber optic gyroscopes, and specifically discloses a closed-loop compensation method for suppressing the wavelength dependence of the scale factor of a fiber optic gyroscope. By utilizing the non-periodicity of the interference curve of a fiber optic gyroscope with a broadband light source, the reset light intensity error at the moment of the staircase wave reset is calculated, and the change of the central wavelength is monitored in real time; by dynamically adjusting and compensating the reset height of the staircase wave, the light intensity value at the moment of the staircase wave reset is made equal to the light intensity value before reset through real-time closed-loop control; finally, by using the mathematical model of the compensation change amount of the staircase wave reset height and the change amount of the scale factor, the compensation for the wavelength dependence of the scale factor of the fiber optic gyroscope is realized. The present invention solves the problem that the scale factor of the fiber optic gyroscope changes with the central wavelength, resulting in a decrease in the scale factor stability of the fiber optic gyroscope.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber optic gyroscopes, and particularly relates to a closed-loop compensation method for suppressing the wavelength dependence of the scale factor of a fiber optic gyroscope. Background Art

[0002] A fiber optic gyroscope is an angular rate sensor based on the Sagnac effect, with the characteristics of high precision, small volume, and large dynamic range. In a fiber optic gyroscope, a closed-loop control method is usually adopted to feedback-control the phase difference sensed by the fiber optic loop using a Y-waveguide phase modulator, which not only improves the linearity of the scale factor of the fiber optic gyroscope but also increases the maximum measurement range of the fiber optic gyroscope. However, in dynamic angle measurement and high-speed rotation scenarios, the scale factor error is still the main error source for the fiber optic gyroscope to measure the rotational speed.

[0003] Fiber optic gyroscopes usually use a broadband light source similar to a superluminescent diode (SLD) to increase the coherence length of the interfering light, thereby reducing the Kerr effect and Shupe effect in the optical path. However, the central wavelength of the broadband light source is not stable and has certain fluctuations with time, temperature, and light intensity. In traditional engineering applications, it is difficult to measure the change in the central wavelength, and usually, additional complex optical systems and signal processing systems need to be added, which is unacceptable for fiber optic gyroscopes with limited volume. Due to the wavelength dependence of the scale factor of the fiber optic gyroscope, the stability of the scale factor of the fiber optic gyroscope decreases, restricting the application of the fiber optic gyroscope in measurement fields such as high-precision and large rotational speed. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that the scale factor of the fiber optic gyroscope changes with the central wavelength, resulting in a decrease in the stability of the scale factor of the fiber optic gyroscope, and a closed-loop compensation method for suppressing the wavelength dependence of the scale factor of the fiber optic gyroscope is proposed.

[0005] The technical solution of the present invention is as follows: A closed-loop compensation method for suppressing the wavelength dependence of the scale factor of a fiber optic gyroscope includes the following steps:

[0006] Set the modulation sequence and modulation amplitude of the fiber optic gyroscope to generate a modulation signal, and set the reset threshold and reset height of the staircase wave;

[0007] Demodulate the rotational speed error and gain error according to the demodulation sequence, and then input the demodulated rotational speed error into a rotational speed integrator and a staircase wave integrator to generate a staircase wave signal, realizing a primary closed-loop control feedback for the rotational speed; input the gain error into a reference voltage integrator to adjust the reference voltage of the D / A converter in the subsequent feedback channel, so that the gain coefficient of the feedback channel remains unchanged, realizing a secondary closed-loop control for the feedback gain;

[0008] If the staircase wave signal exceeds the reset threshold of the staircase wave, reset is triggered, and according to the staircase wave reset state and the modulation sequence state, the reset optical intensity error is demodulated according to the staircase wave reset optical intensity error demodulation sequence; if the staircase wave signal does not exceed the reset threshold of the staircase wave, the staircase wave signal is superimposed on the modulation signal.

[0009] After triggering the reset, the demodulated reset optical intensity error is accumulated and integrated through the staircase wave reset height compensation integrator to calculate the compensated digital quantity of the staircase wave reset height.

[0010] The compensated digital quantity of the staircase wave reset height is truncated, and then the staircase wave signal is reset to realize the three - closed - loop control feedback of the staircase wave reset height; the truncated compensated digital quantity of the staircase wave reset height is smoothed and filtered, and the compensated quantity reference value under the reference condition is collected, and the smoothed compensated digital quantity of the staircase wave reset height is divided by the compensated quantity reference value to obtain the reset height compensation change quantity.

[0011] According to the mathematical relationship between the reset height compensation change quantity and the scale factor change quantity, the scale factor compensation coefficient is calculated.

[0012] The original number of the fiber optic gyro is multiplied by the scale factor compensation coefficient to obtain the compensated rotation speed value output, realizing the suppression of the wavelength dependence of the scale factor.

[0013] Preferably, the modulation sequence is , where is the staircase wave reset height value, and the corresponding phase difference is 2π; [[ID=2"]] is the modulation digital quantity; the duration of each modulation amplitude is , and the period of the modulation sequence is , is the transit time of light propagating in the fiber optic loop; the modulation sequence makes the phase difference generated by the two interfering light beams be , is arbitrarily set within (π / 2, π);

[0014] The optical intensity signal corresponding to the modulation sequence is converted into a digital signal through an A / D converter, and the signal digital quantity corresponding to the modulation sequence is collected through an FPGA , , and to obtain the signal digital quantity sequence as .

[0015] Preferably, the demodulation method of the rotation speed error is specifically:

[0016]

[0017] Among them, Indicates the rotational speed error;

[0018] Input the rotational speed error into the rotational speed integrator for accumulation to obtain the rotational speed value :

[0019]

[0020] Input the rotational speed value into the stepped wave integrator for accumulation to obtain the stepped wave signal :

[0021]

[0022] The stepped wave integrator integrates once every 1 transit time.

[0023] Preferably, when the stepped wave signal exceeds the reset threshold of the stepped wave, trigger a reset, and according to the stepped wave reset state and the modulation sequence state, demodulate the reset light intensity error according to the stepped wave reset light intensity error demodulation sequence, which specifically includes the following steps:

[0024] Set the upper threshold and the lower threshold of the reset threshold of the stepped wave;

[0025] If the stepped wave signal is greater than the upper threshold , then perform a positive reset on the stepped wave, that is:

[0026] ;

[0027] Among them, represents the stepped wave after positive reset, is the stepped wave signal, is the stepped wave reset height value;

[0028] If the stepped wave signal is less than the lower threshold value , then perform a negative reset on the stepped wave, that is:

[0029]

[0030] Among them, represents the stepped wave after negative reset;

[0031] If the stepped wave signal is less than or equal to the upper threshold and greater than or equal to the lower threshold, no reset is performed;

[0032] When the modulation sequence at the time of reset is , it is positive modulation, and when the modulation sequence at the time of reset is , it is negative modulation; among them, is the modulation digital quantity;

[0033] Demodulate the reset optical intensity error when positive reset is performed under positive modulation and negative reset is performed under negative modulation.

[0034] Preferably, when the set stepped-wave reset phase difference is equal to 2π, the reset optical intensity error is caused by the non-periodicity of the interference curve of the broadband light source;

[0035] When performing positive reset under positive modulation, the stepped-wave reset optical intensity error demodulation sequence is:

[0036]

[0037] When performing negative reset under negative modulation, the stepped-wave reset optical intensity error demodulation sequence is:

[0038] .

[0039] Preferably, the formula for truncating the digital quantity of the stepped-wave reset height compensation is:

[0040]

[0041] where, represents the digital quantity of the stepped-wave reset height compensation after truncation, represents rounding the divisor, represents the digital quantity of the stepped-wave reset height compensation, represents the number of digits for truncation, is related to the response time of the fiber optic gyroscope.

[0042] Preferably, the reset of the stepped-wave signal is performed to achieve a three-time closed-loop control feedback on the stepped-wave reset height, which specifically includes the following steps:

[0043] Dynamically adjust the reset height of the stepped-wave according to the stepped-wave reset state to obtain the adjusted reset height of the stepped-wave ;

[0044] Perform stepped-wave reset according to the adjusted reset height of the stepped-wave to obtain the reset stepped-wave;

[0045] Superimpose the reset stepped-wave and the modulation signal to achieve a three-time closed-loop control feedback on the stepped-wave reset height.

[0046] Preferably, the method for dynamically adjusting the reset height of the stepped-wave according to the stepped-wave reset state is specifically:

[0047] If the stepped-wave reset state is positive reset under positive modulation, then in the signal digital quantity The reset height compensation digital quantity of the stepped wave after subtracting the truncation from the reset height of the stepped wave under modulation, from the signal digital quantity The reset height compensation digital quantity of the stepped wave after adding the truncation to the reset height of the stepped wave under modulation;

[0048] If the stepped wave reset state is negative reset under negative modulation, then from the signal digital quantity The reset height compensation digital quantity of the stepped wave after subtracting the truncation from the reset height of the stepped wave under modulation, from the signal digital quantity The reset height compensation digital quantity of the stepped wave after adding the truncation to the reset height of the stepped wave under modulation.

[0049] Preferably, the specific operation of resetting the stepped wave according to the adjusted reset height of the stepped wave is as follows: <w

[0050] If it is a positive reset, then the stepped wave after reset The calculation formula is:

[0051]

[0052] Wherein, Is the stepped wave signal;

[0053] If it is a positive reset, then the stepped wave after reset The calculation formula is:

[0054] .

[0055] Preferably, the mathematical relationship between the reset height compensation change amount and the scale factor change amount is a linear equation or a polynomial equation, and the coefficients of the linear equation or the polynomial equation are related to the fiber optic gyro parameters and are obtained by fitting using numerical calculation methods.

[0056] The beneficial effects of the present invention are:

[0057] 1. Directly extract relevant information on the change in the central wavelength from the interference signal, without affecting the demodulation and closed-loop control of the original rotational speed error and gain error, and can monitor the change amount of the central wavelength in real time;

[0058] 2. Use closed-loop integral control to effectively reduce the influence of random noise and short-term disturbances;

[0059] 3. The reset height compensation amount is insensitive to the optical power, so the manufacturing deviation and aging of the light source do not affect the compensation model, and it has strong adaptability;

[0060] 4. It is implemented in the FPGA, without changing the existing optical path and hardware, and the engineering implementation is simple and reliable. Description of the Drawings

[0061] Figure 1The block diagram of the fiber optic gyroscope is shown as follows.

[0062] Figure 2 The flowchart of a closed-loop compensation method for suppressing the wavelength dependence of the scale factor of the fiber optic gyroscope is shown as follows.

[0063] Figure 3 The interference curve of the broadband light source is shown as follows.

[0064] Figure 4 The interference light intensity in the presence of rotational speed phase and gain errors is shown as follows.

[0065] Figure 5 The interference light intensity during positive reset under positive modulation is shown as follows.

[0066] Figure 6 The interference light intensity during negative reset under negative modulation is shown as follows.

[0067] Figure 7 The reset height of the adjusted staircase wave during positive reset under positive modulation is shown as follows.

[0068] Figure 8 The reset height of the adjusted staircase wave during negative reset under negative modulation is shown as follows.

[0069] Figure 9 The modulation depth is shown as follows When it is 7π / 8, the compensation model of the change in reset height compensation and the change in scale factor is as follows. Specific implementation manners

[0070] Now, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the embodiments shown and described in the drawings are merely exemplary, intended to illustrate the principles and spirit of the present invention, and not to limit the scope of the present invention.

[0071] The block diagram of the fiber optic gyroscope is as Figure 1 shown. According to the Sagnac effect of the fiber optic gyroscope, the phase difference between the two interfering light beams caused by the rotational speed is:

[0072]

[0073] wherein, is the length of the fiber optic loop, is the diameter of the fiber optic loop, is the central wavelength, is the pi, is the transmission speed of light in vacuum, is the input angular rate.

[0074] In the fiber optic gyroscope, a Y waveguide phase modulator is used to change the phase of the two light beams , and its expression is:

[0075]

[0076] Wherein, is the applied voltage; is the spacing of the planar electrodes; is the overlap integral factor of the electric field and the optical field; is the length of the modulation electrode; is the extraordinary optical refractive index; is the electro-optic coefficient; is the central wavelength.

[0077] In a fiber optic gyroscope, the digital quantity is converted into an analog quantity after passing through a D / A converter and an operational amplifier, and is applied to the Y-waveguide phase modulator. Therefore, the feedback phase through the Y-waveguide phase modulation is:

[0078]

[0079] Wherein, is the gain of the D / A converter, is the gain of the amplifier, is the output digital quantity of the fiber optic gyroscope.

[0080] In a closed-loop control system, the feedback phase is equal in magnitude and opposite in direction to the Sagnac phase:

[0081]

[0082] Therefore, the scale factor of the fiber optic gyroscope is:

[0083]

[0084] Wherein, is the modulation coefficient of the Y-waveguide, .

[0085] In engineering applications, the staircase wave signal cannot increase infinitely and needs to be reset. In order to reduce the influence of the staircase wave reset and the change of the gain coefficient of the feedback channel such as the high and low temperature characteristics of the Y-waveguide phase modulator on the rotational speed error, the gain error is usually demodulated and secondary closed-loop control is performed to keep the phase difference at the reset moment always 2π. Assuming that the reset height digital quantity of the staircase wave is , then

[0086]

[0087] Substituting the above formula into the calculation formula of the scale factor of the fiber optic gyroscope, the scale factor of the fiber optic gyroscope is:

[0088]

[0089] It can be seen that for a fiber optic gyroscope using closed-loop control, its scale factor is proportional to the length of the fiber optic loop , the diameter of the fiber optic loop and the reset height and inversely proportional to the central wavelength .

[0090] Embodiment 1:

[0091] As Figure 2 shown, a closed-loop compensation method for suppressing the wavelength dependence of the scale factor of a fiber optic gyroscope utilizes the non-periodicity of the interference curve of a wide-spectrum light source fiber optic gyroscope to calculate the reset light intensity error at the moment of the stepped wave reset, and real-time monitors the change of the central wavelength; by dynamically adjusting and compensating the reset height of the stepped wave, real-time closed-loop control is performed to make the light intensity value at the time of the stepped wave reset equal to the light intensity value before the reset; finally, a mathematical model of the compensation variation of the stepped wave reset height and the variation of the scale factor is used to achieve the compensation of the wavelength dependence of the scale factor of the fiber optic gyroscope, including the following steps:

[0092] S1. Set the modulation sequence and modulation amplitude of the fiber optic gyroscope to generate a square wave modulation signal, so that the fiber optic gyroscope includes 4 modulation states within two adjacent transit times of the period, and set the reset threshold and reset height of the stepped wave;

[0093] The fiber optic gyroscope usually uses a wide-spectrum light source as the light source, and its interference curve is non-periodic. The interference amplitude decreases with the increase of the interference fringe order and finally loses the interference characteristics. The interference curve of the wide-spectrum light source is as shown in the appendix Figure 3 , and the expression of the interference light intensity is:

[0094]

[0095] Among them, represents the interference light intensity, is the central wavelength, represents the cosine function, represents the natural exponential function, is the input optical power, is the spectral width, is the phase difference between the two beams of light in the fiber optic loop.

[0096] The modulation sequence is , where is the stepped wave reset height value, and the corresponding phase difference is 2π; is the modulation digital quantity; the duration of each modulation amplitude is , and the period of the modulation sequence is , is the transit time of light propagating in the fiber optic loop; the modulation sequence causes a phase difference between the two interfering light beams to be , the modulation depth is arbitrarily set within the range of (π / 2, π). When taking , then ; the optical intensity signal corresponding to the modulation sequence is converted into a digital signal by an A / D converter and collected by an FPGA. The corresponding signal digital quantity sequence is , and is stored in the corresponding register according to the state machine. When there are rotational speed phase and gain errors, the interference optical intensity generated by the modulation sequence is as Figure 4 shown.

[0097] S2. Demodulate the rotational speed error and gain error according to the demodulation sequence. Among them, the rotational speed error outputs the rotational speed value through a rotational speed integrator, and the rotational speed value is input to a staircase wave integrator to generate a staircase wave signal, realizing the first closed-loop control feedback of the fiber optic gyroscope to the rotational speed;

[0098] The demodulation method of the rotational speed error is specifically as follows:

[0099]

[0100] Among them, represents the rotational speed error;

[0101] Input the rotational speed error into the rotational speed integrator for accumulation to obtain the rotational speed value :

[0102]

[0103] Input the rotational speed value into the staircase wave integrator for accumulation to obtain the staircase wave signal :

[0104]

[0105] The staircase wave integrator integrates once every 1 transit time;

[0106] The demodulation method of the gain error is specifically as follows:

[0107]

[0108] Among them, represents the gain error.

[0109] S3. When the staircase wave signal exceeds the reset threshold of the staircase wave, trigger the reset. According to the staircase wave reset state and the modulation sequence state, demodulate the reset optical intensity error according to the staircase wave reset optical intensity error demodulation sequence;

[0110] Set the upper threshold and the lower threshold :

[0111]

[0112]

[0113] Determine whether the staircase wave signal exceeds the threshold value. If the digital quantity of the staircase wave signal is greater than the upper threshold , then perform a positive reset on the staircase wave, that is:

[0114] ;

[0115] Among them, represents the staircase wave after positive reset, is the staircase wave signal, is the reset height value of the staircase wave;

[0116] If the staircase wave signal is less than the lower threshold value , then perform a negative reset on the staircase wave, that is:

[0117]

[0118] Among them, represents the staircase wave after negative reset.

[0119] If the staircase wave signal is less than or equal to the upper threshold and greater than or equal to the lower threshold, no reset is performed.

[0120] When the modulation sequence at the time of reset is , it is positive modulation. When the modulation sequence at the time of reset is , it is negative modulation; when performing positive reset under positive modulation and negative reset under negative modulation, demodulate the reset optical intensity error; the interference optical intensity when performing positive reset under positive modulation is as Figure 5 shown, and the staircase wave reset optical intensity error demodulation sequence is:

[0121]

[0122] The interference optical intensity when performing negative reset under negative modulation is as Figure 6 shown, and the staircase wave reset optical intensity error demodulation sequence is:

[0123] .

[0124] S4. After triggering the reset, accumulate and integrate the reset optical intensity error through the staircase wave reset height compensation integrator to calculate the compensation digital quantity of the staircase wave reset height :

[0125]

[0126] S5. Modify the stepped wave reset height, and calculate the change amount of the reset height compensation; to improve the stability margin of the closed-loop control of the reset light intensity error and reduce the influence of noise, truncate the digital quantity of the stepped wave reset height compensation:

[0127]

[0128] Among them, represents the digital quantity of the stepped wave reset height compensation after truncation, represents rounding the divisor, represents the number of bits for truncation, is related to the response time of the fiber optic gyroscope. Then, add or subtract according to the stepped wave reset state and the stepped wave reset height, and dynamically adjust the reset height of the stepped wave as shown in Figure 7 and Figure 8 Specifically:

[0129] If the stepped wave reset state is positive reset under positive modulation, the reset height of the stepped wave under the signal digital quantity modulation should subtract the digital quantity of the stepped wave reset height compensation. The calculation formula is:

[0130]

[0131] Among them, represents the adjusted reset height of the stepped wave;

[0132] Under the signal digital quantity modulation, the reset height of the stepped wave should add the digital quantity of the stepped wave reset height compensation. The calculation formula is;

[0133] ;

[0134] If the stepped wave reset state is negative reset under negative modulation, the reset height of the stepped wave under the signal digital quantity modulation should subtract the digital quantity of the stepped wave reset height compensation. The calculation formula is:

[0135]

[0136] Under the signal digital quantity modulation, the reset height of the stepped wave should add the digital quantity of the stepped wave reset height compensation. The calculation formula is:

[0137]

[0138] By adjusting the reset height value in real time under different reset states, the change of the central wavelength can be tracked.

[0139] Smoothing and filtering the digital quantity of the stepped wave reset height compensation to obtain Collect the reset height compensation amount under the reference environmental conditions and set it as When the central wavelength changes, the compensation amount of the stepped wave reset height also changes. The change amount of the stepped wave reset height compensation is:

[0140]

[0141] Among them, a sliding window or a low-pass filter is selected for smoothing and filtering.

[0142] By adjusting the stepped wave reset height to change the phase difference at the reset moment, so that the light intensity value at the reset time is equal to that before the reset. There is a formula:

[0143]

[0144] Among them, is the compensation phase difference corresponding to the reset height compensation amount. According to the above formula, the mathematical relationship between the central wavelength and the compensation phase difference can be fitted, and the mathematical relationship between the central wavelength change amount and the reset height compensation change amount can be obtained.

[0145] When the central wavelength changes, the light intensity at the reset moment is not equal to the light intensity value before the reset, and the light intensity difference at the stepped wave reset moment is no longer zero. After the demodulation and closed-loop control in steps S3 to S5, the compensation amount of the stepped wave reset height also changes. The change amount of the stepped wave reset height compensation is:

[0146]

[0147] Among them, is the reference reset height compensation amount, is the reset height compensation amount after the change of the central wavelength.

[0148] S6. According to the mathematical relationship between the reset height compensation change amount and the scale factor change amount, calculate the scale factor compensation coefficient; the mathematical relationship between the reset height compensation change amount and the scale factor change amount is a linear equation or a polynomial equation, and the coefficients of the linear equation or the polynomial equation are related to the fiber optic gyro parameters and are obtained by fitting using numerical calculation methods. According to the light intensity equality before and after the reset, the relationship between the reset height compensation phase difference and the central wavelength can be calculated. Since the relationship between the fiber optic gyro scale factor and the central wavelength is as shown in the formula , a mathematical model between the reset height compensation change amount and the scale factor change amount can be established. Using numerical calculation methods, the reset height compensation change amount and the scale factor change amount Fitted to a first-order or multi-order compensation model, and its coefficients are related to parameters such as the set modulation depth and so on. When the modulation depth is , the compensation model and coefficients of the reset height compensation variation and the scale factor variation are as Figure 9 shown.

[0149] Due to the modulation depth set in step S1, when using a first-order compensation model , the scale factor compensation coefficient can be obtained.

[0150] S7. Multiply the original data of the fiber optic gyro by the scale factor compensation coefficient to obtain the compensated rotational speed value output, realizing the suppression of the wavelength dependence of the scale factor;

[0151] Multiply the rotational speed value in the demodulation data of the fiber optic gyro in step S2 by the scale factor compensation coefficient , and the rotational speed value output compensated with the central wavelength can be obtained, reducing the dependence on the central wavelength.

[0152] Those of ordinary skill in the art will realize that the embodiments described herein are to help the reader understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations without departing from the essence of the present invention based on the technical revelations disclosed in the present invention, and these deformations and combinations are still within the protection scope of the present invention.

Claims

1. A closed-loop compensation method for suppressing the wavelength dependence of the scale factor of a fiber optic gyroscope, characterized in that, It includes the following steps: Set the modulation sequence and modulation amplitude of the fiber optic gyroscope to generate a modulation signal, and set the reset threshold and reset height of the staircase wave; Demodulate the rotational speed error and gain error according to the demodulation sequence, and then input the demodulated rotational speed error into the rotational speed integrator and the staircase wave integrator to generate a staircase wave signal, realizing the first closed-loop control feedback of the rotational speed; input the gain error into the reference voltage integrator to adjust the reference voltage of the D / A converter in the subsequent feedback channel, so that the gain coefficient of the feedback channel remains unchanged, realizing the second closed-loop control of the feedback gain; If the staircase wave signal exceeds the reset threshold of the staircase wave, trigger a reset, and demodulate the reset light intensity error according to the staircase wave reset state and the modulation sequence state according to the staircase wave reset light intensity error demodulation sequence; if the staircase wave signal does not exceed the reset threshold of the staircase wave, then superimpose the staircase wave signal and the modulation signal; After triggering the reset, accumulate and integrate the demodulated reset light intensity error through the staircase wave reset height compensation integrator to calculate the compensation digital quantity of the staircase wave reset height; Truncate the compensation digital quantity of the staircase wave reset height, and then reset the staircase wave signal to realize the third closed-loop control feedback of the staircase wave reset height; smooth and filter the truncated compensation digital quantity of the staircase wave reset height, collect the compensation quantity reference value under the reference condition, and divide the smoothed compensation digital quantity of the staircase wave reset height by the compensation quantity reference value to obtain the reset height compensation variation; Calculate the scale factor compensation coefficient according to the mathematical relationship between the reset height compensation variation and the scale factor variation; Multiply the original number of the fiber optic gyroscope by the scale factor compensation coefficient to obtain the compensated rotational speed value output, realizing the suppression of the wavelength dependence of the scale factor.

2. The closed-loop compensation method for suppressing the wavelength dependence of the scale factor of a fiber optic gyroscope according to claim 1, wherein, The modulation sequence is , where is the step-wave reset height value, and the corresponding phase difference is 2π; is the modulation digital quantity; the duration of each modulation amplitude is , and the period of the modulation sequence is , is the transit time of light propagating in the fiber loop; The modulation sequence makes the phase difference generated by the two interfering light beams be , arbitrarily set within the range of (π / 2, π); The light intensity signal corresponding to the modulation sequence is converted into a digital signal by an A / D converter, and the digital quantity of the signal corresponding to the modulation sequence is collected by FPGA. 、 、 and , the signal digital sequence is .

3. The closed-loop compensation method for suppressing the wavelength dependence of the scale factor of the fiber optic gyroscope according to claim 2, wherein The demodulation method of the rotational speed error is specifically as follows: Among them, represents the rotational speed error; The rotational speed error is input into a rotational speed integrator for accumulation to obtain a rotational speed value : The rotational speed value is input into a stepped wave integrator for accumulation to obtain a stepped wave signal : The staircase wave integrator integrates once every 1 transit time.

4. The closed-loop compensation method for suppressing the wavelength dependence of the scale factor of the fiber optic gyroscope according to claim 2, characterized in that, When the staircase wave signal exceeds the reset threshold of the staircase wave, trigger a reset, and demodulate the reset light intensity error according to the staircase wave reset state and the modulation sequence state according to the staircase wave reset light intensity error demodulation sequence, specifically including the following steps: Set the upper threshold of the reset threshold of the staircase wave and the lower threshold ; If the staircase wave signal is greater than the upper threshold , then perform a positive reset on the staircase wave, i.e.: ； Among them, represents the stepped wave after positive reset, is the stepped wave signal, is the stepped wave reset height value; If the staircase wave signal is less than the lower threshold value , then perform negative reset on the staircase wave, that is: Among them, represents the sawtooth wave after negative reset; If the staircase wave signal is less than or equal to the upper threshold and greater than or equal to the lower threshold, no reset is performed; When the modulation sequence at reset is , it is positive modulation. When the modulation sequence at reset is , it is negative modulation; where is the modulation digital quantity. During positive reset under positive modulation and negative reset under negative modulation, demodulate the reset light intensity error.

5. The closed-loop compensation method for suppressing the wavelength dependence of the scale factor of a fiber optic gyroscope according to claim 4, characterized in that When the set staircase wave reset phase difference is equal to 2π, the reset light intensity error is caused by the non-periodicity of the broadband light source interference curve; When performing positive reset under positive modulation, the stepped wave reset optical intensity error demodulation sequence is as follows: When performing negative reset under negative modulation, the stepped wave reset light intensity error demodulation sequence is as follows: 。 6. The closed-loop compensation method for suppressing the wavelength dependence of the scale factor of a fiber optic gyroscope according to claim 1, wherein The formula for truncating the compensation digital quantity of the staircase wave reset height is: Among them, represents the digital quantity of the stepped wave reset height compensation after truncation, represents taking the integer of the divisor, represents the digital quantity of the stepped wave reset height compensation, represents the number of digits for truncation, which is related to the response time of the fiber optic gyroscope.

7. The closed-loop compensation method for suppressing the wavelength dependence of the scale factor of a fiber optic gyroscope according to claim 5, characterized in that The reset of the staircase wave signal to realize the third closed-loop control feedback of the staircase wave reset height specifically includes the following steps: Dynamically adjust the reset height of the staircase wave according to the staircase wave reset state to obtain the reset height of the adjusted staircase wave ; Perform staircase wave reset according to the adjusted reset height of the staircase wave to obtain the reset staircase wave; Superimpose the reset staircase wave and the modulation signal to realize the third closed-loop control feedback of the staircase wave reset height.

8. The closed-loop compensation method for suppressing the wavelength dependence of the scale factor of a fiber optic gyroscope according to claim 7, characterized in that The method for dynamically adjusting the reset height of the staircase wave according to the staircase wave reset state is specifically as follows: If the stepped wave reset state is positive reset under positive modulation, then subtract the compensated digital quantity of the reset height of the stepped wave after truncation from the reset height of the stepped wave under the signal digital quantity modulation, and add the compensated digital quantity of the reset height of the stepped wave after truncation to the reset height of the stepped wave under the signal digital quantity modulation; If the stepped wave reset state is negative reset under negative modulation, then subtract the compensated digital quantity of the stepped wave reset height after truncation from the reset height of the stepped wave under the signal digital quantity modulation, and add the compensated digital quantity of the stepped wave reset height after truncation to the reset height of the stepped wave under the signal digital quantity modulation.

9. The closed-loop compensation method for suppressing the wavelength dependence of the scale factor of a fiber optic gyroscope according to claim 7, characterized in that, The staircase wave reset according to the adjusted reset height of the staircase wave is specifically: If it is a positive reset, the stepped wave after reset The calculation formula is as follows: Among them, is a stepped wave signal; If it is a positive reset, the stepped wave after reset has the following calculation formula: 。 10. The closed-loop compensation method for suppressing the wavelength dependence of the scale factor of a fiber optic gyroscope according to claim 1, characterized in that, The mathematical relationship between the reset height compensation variation and the scale factor variation is a linear equation or a polynomial equation. The coefficients of the linear equation or the polynomial equation are related to the parameters of the fiber optic gyroscope and are obtained by fitting using numerical calculation methods.

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