Precision maintaining method based on adaptive adjustment of modulation depth of fiber-optic gyroscope

Abstract

The invention provides a precision maintaining method based on self-adaptive adjustment of the modulation depth of a fiber-optic gyroscope, belongs to the technical field of fiber-optic gyroscope modulation, and solves the problem that the modulation depth is difficult to adjust in a self-adaptive manner in the prior art. The method comprises the following steps: constructing a relationship between an optimal modulation depth and a step height; acquiring an optical interference signal output by an optical path system of the fiber-optic gyroscope in real time, and determining the optimal modulation depth of the current optical power according to 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 an optical path system of the fiber-optic gyroscope to realize the precision keeping control of the fiber-optic gyroscope.

Description

Technical Field

[0001] This invention relates to the field of fiber optic gyroscope modulation technology, and in particular to a method for maintaining accuracy based on adaptive adjustment of fiber optic gyroscope modulation depth. Background Technology

[0002] As a high-precision inertial sensor, the accuracy of a fiber optic gyroscope primarily depends on the stability of the optical power within its optical path system. In practical applications, the optical path system of a fiber optic gyroscope is affected by various factors, such as temperature variations, fiber aging, and fluctuations in light source power. These factors can cause changes in optical power, ultimately reducing its accuracy performance.

[0003] Traditional methods for adjusting the modulation depth of fiber optic gyroscopes are mostly based on fixed parameters, which cannot adapt to dynamic changes in optical power in real time. For example, in some fiber optic gyroscope systems, the modulation depth is preset. Once the optical power changes, the matching relationship between the modulation depth and the optical power is broken, leading to a decrease in the accuracy of the fiber optic gyroscope. In addition, some methods can adjust the modulation depth to a certain extent, but the adjustment process is complex and lacks real-time performance, making it difficult to meet the accuracy maintenance requirements of high-precision fiber optic gyroscopes in dynamic environments.

[0004] Therefore, how to adaptively adjust the modulation depth based on the optical interference signal output in real time by the optical path system of the fiber optic gyroscope in order to maintain the measurement accuracy of the fiber optic gyroscope is a technical problem that urgently needs to be solved in the field of fiber optic gyroscope technology. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a precision maintenance method based on adaptive adjustment of modulation depth of fiber optic gyroscope, in order to solve the problem that the existing technology is difficult to adaptively adjust the modulation depth.

[0006] This invention provides a precision maintenance method based on adaptive adjustment of fiber optic gyroscope modulation depth, the method comprising:

[0007] Establish the relationship between the optimal modulation depth and step height;

[0008] The optical interference signal output in real time from the fiber optic gyroscope optical path system is acquired, and the optimal modulation depth of the current optical power is determined based on the relationship between the optimal modulation depth and the step height.

[0009] Based on the optimal modulation depth and additional modulation signal of the current optical power, an analog modulation signal is generated;

[0010] The analog modulation signal is input into the optical path system of the fiber optic gyroscope to achieve precision control of the fiber optic gyroscope.

[0011] Based on the above solution, the present invention also makes the following improvements:

[0012] Furthermore, the process of establishing the optimal relationship between modulation depth and step height involves:

[0013] Construct a curve relating the optical power of a fiber optic gyroscope to the optimal modulation depth;

[0014] Based on the curve relationship between the optical power of the fiber optic gyroscope and the optimal modulation depth, the relationship between the optimal modulation depth and the step height is constructed.

[0015] Furthermore, a curve relationship between the optical power of the fiber optic gyroscope and the optimal modulation depth is constructed, and the following steps are performed:

[0016] Multiple optical power points are set at fixed power intervals; at each optical power point, multiple modulation depths are set at fixed modulation depth intervals.

[0017] For each optical power point, calculate the RWC corresponding to each modulation depth at the current optical power point, and take the modulation depth when the RWC takes the minimum value as the optimal modulation depth corresponding to the current optical power point.

[0018] Based on each optical power point and its corresponding optimal modulation depth, the relationship between optical power and optimal modulation depth is fitted to establish a curve relationship between optical power and optimal modulation depth.

[0019] Furthermore, a linear equation in two variables is used to fit the relationship between optical power and optimal modulation depth; during the fitting process, quadratic fitting parameters a0, a1, and a2 are determined; a quadratic fitting curve relationship between optical power and optimal modulation depth is established, expressed as:

[0020] Φ 0i =a0+a1P 0i +a2P 0i 2 (3)

[0021] Among them, P 0i Φ represents optical power. 0i This indicates the optimal modulation depth corresponding to the current optical power.

[0022] Furthermore, the relationship between the optimal modulation depth and the step height is expressed as:

[0023] Φ 0i =b0+b1ΔC i +b2ΔC i 2 (1)

[0024] Where, ΔC i Indicates the step height, Φ 0iIndicates the optimal modulation depth; b0 = a0, b1 = a1 / K, b2 = a2 / K, K = P 0i / ΔC i .

[0025] Furthermore, based on the relationship between the optimal modulation depth and the step height, the optimal modulation depth for the current optical power is determined, and the following steps are performed:

[0026] The optical interference signal is amplified and converted from analog to digital to generate a digital interference signal;

[0027] The digital interferometric signal is decomposed into a rate signal to be demodulated and an optical power signal to be demodulated.

[0028] Additional interference demodulation is performed on the optical power signal to be demodulated to obtain the demodulated amount of optical power; and the optimal modulation depth corresponding to the current optical power is obtained according to the relationship between the optimal modulation depth and the step height.

[0029] Furthermore, the generation of the analog modulation signal involves:

[0030] Generate a stepped wave signal based on the demodulated rate signal;

[0031] Generate the corresponding normal modulation signal based on the optimal modulation depth;

[0032] The generated stepped wave signal, the normal modulation signal, and the additional modulation signal are superimposed to obtain the digital modulation signal;

[0033] The digital modulation signal is converted from digital to analog and amplified to generate an analog modulation signal.

[0034] Furthermore, the period of the additional modulation signal is 2Nτ, where,

[0035] τ is the transit time of the fiber optic gyroscope, and N is a positive integer;

[0036] The duration of the additional interference signal is 2τ within one period of the additional modulation signal.

[0037] Furthermore, the optical power signal to be demodulated is demodulated to obtain the demodulated optical power, and the following steps are performed:

[0038] Demodulate the digital signal amplitude C1 with additional interference signal and the digital signal amplitude C2 without additional interference signal from the optical power signal to be demodulated;

[0039] The step height ΔC is calculated using the formula C1 - C2, and is used as the demodulation amount of the optical power.

[0040] Furthermore, the step of generating a stepped wave signal based on the demodulated rate signal is performed as follows:

[0041] Rate demodulation is performed 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.

[0042] Integrate the closed-loop feedback step signal to generate a step wave signal.

[0043] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0044] The application provides a precision preservation method based on adaptive adjustment of fiber optic gyroscope modulation depth, which has the following technical advantages:

[0045] (1) Improve the measurement accuracy of fiber optic gyroscopes

[0046] By establishing the relationship between the optimal modulation depth and the step height, as well as the curve relationship between optical power and the optimal modulation depth, the optimal modulation depth for the current optical power can be accurately determined based on the optical interference signal output in real time by the fiber optic gyroscope optical path system. This adaptive adjustment method enables the fiber optic gyroscope to adjust the modulation depth in a timely manner when the optical power changes, maintaining its measurement accuracy and effectively avoiding the accuracy degradation problem caused by the mismatch between modulation depth and optical power.

[0047] (2) Enhance the adaptability of fiber optic gyroscopes

[0048] This method can monitor the optical power changes of the fiber optic gyroscope's optical path system in real time and quickly adjust the modulation depth accordingly, enabling it to adapt to various complex dynamic environments, such as temperature changes and fiber aging. This adaptive capability greatly enhances the stability and reliability of the fiber optic gyroscope in different application scenarios, improving its performance in practical applications.

[0049] (3) Simplify the modulation depth adjustment process

[0050] The method described in this application employs a series of efficient signal processing and computational steps, such as signal amplification and analog-to-digital conversion of the optical interference signal, decomposition of the digital interference signal, and demodulation of the optical power signal. This enables the rapid and accurate determination of the optimal modulation depth and the generation of the corresponding analog modulation signal. Compared to traditional modulation depth adjustment methods, this method offers a simpler and faster adjustment process, improving the overall operating efficiency of the fiber optic gyroscope system.

[0051] (4) Reduce the error of fiber optic gyroscopes

[0052] By accurately calculating the step height and determining the optimal modulation depth based on the relationship between the step height and the optimal modulation depth, the random walk error (RWC) of the fiber optic gyroscope can be effectively reduced. At each optical power point, multiple modulation depths are set at fixed modulation depth intervals, and the RWC corresponding to each modulation depth is calculated. The modulation depth at which the RWC reaches its minimum value is taken as the optimal modulation depth for the current optical power point. This optimization method enables the fiber optic gyroscope to maintain a low error level under different optical power conditions, improving the accuracy of its measurement results.

[0053] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0054] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0055] Figure 1 A flowchart illustrating the accuracy preservation method based on adaptive adjustment of fiber optic gyroscope modulation depth provided in an embodiment of the present invention;

[0056] Figure 2 A schematic diagram illustrating the quadratic fitting curve relationship between optical power and optimal modulation depth provided in an embodiment of the present invention;

[0057] Figure 3 This is a schematic diagram of a modulation and demodulation system for maintaining the accuracy of a fiber optic gyroscope, provided in an embodiment of the present invention.

[0058] Figure 4 This is a schematic diagram of a stepped-wave modulation signal, a normal modulation signal, and an additional modulation signal provided in an embodiment of the present invention;

[0059] Figure 5 This is a schematic diagram of the demodulated power signal provided in an embodiment of the present invention;

[0060] Figure reference numerals: 1-Fiber optic gyroscope optical circuit subsystem, 2-Pre-amplifier and analog-to-digital converter circuit, 3-Demodulation information classification module, 4-Rate information demodulation module, 5-Step wave signal generator, 6-Optical power information demodulation module, 7-Modulation depth adjustment module, 8-Normal modulation signal generation module, 9-Additional modulation signal generation module, 10-Modulation signal combination module, and 11-Digital-to-analog converter and post-amplifier circuit. Detailed Implementation

[0061] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0062] A specific embodiment of the present invention discloses a precision preservation method based on adaptive adjustment of fiber optic gyroscope modulation depth, the flowchart of which is shown below. Figure 1 As shown, the specific explanation is as follows.

[0063] Step S1: Establish the relationship between the optimal modulation depth and step height.

[0064] Step S11: Construct the curve relationship between the optical power of the fiber optic gyroscope and the optimal modulation depth.

[0065] Step S111: Set multiple optical power points according to a fixed power interval; at each optical power point, set multiple modulation depths at a fixed modulation depth interval. For example, for a certain optical power point, the modulation depths are set sequentially to π / 2, ..., π.

[0066] In specific implementation, the modulation depth interval corresponds to the resolution of the digital-to-analog converter. For example, if the number of bits of the digital-to-analog converter is M, then the minimum modulation depth interval ΔΦ0 is determined by formula (2):

[0067]

[0068] Step S112: For each optical power point, calculate the RWC corresponding to each modulation depth at the current optical power point (using the fiber optic gyroscope RWC calculation formula in formula (1)), and take the modulation depth when the RWC takes the minimum value as the optimal modulation depth corresponding to the current optical power point.

[0069] Step S1113: Based on each optical power point and its corresponding optimal modulation depth, fit the relationship between optical power and optimal modulation depth to establish a curve relationship between optical power and optimal modulation depth.

[0070] For example, in this embodiment, a linear equation in two variables is used to fit the relationship between the two. During the fitting process, quadratic fitting parameters a0, a1, and a2 are determined, thereby establishing a quadratic fitting curve relationship between optical power and optimal modulation depth, expressed as:

[0071] Φ 0i =a0+a1P 0i +a2P 0i 2 (3)

[0072] Among them, P 0i Φ represents optical power.0i This indicates the optimal modulation depth corresponding to the current optical power.

[0073] A schematic diagram of the quadratic fitting curve relationship between optical power and optimal modulation depth is shown below. Figure 2 As shown in the figure. This embodiment establishes a quadratic fitting curve relationship between optical power and optimal modulation depth, enabling real-time adjustment of the optimal modulation depth and thus maintaining accuracy.

[0074] Step S12: Based on the curve relationship between the optical power of the fiber optic gyroscope and the optimal modulation depth, construct the relationship between the optimal modulation depth and the step height.

[0075] The step height is proportional to the optical power amplitude; therefore, the relationship between the optimal modulation depth and the step height is expressed as:

[0076] Φ 0i =b0+b1ΔC i +b2ΔC i 2 (4)

[0077] Where, ΔC i Indicates the step height; b0 = a0, b1 = a1 / K, b2 = a2 / K, K = P 0i / ΔC i .

[0078] Step S2: Obtain the optical interference signal output in real time by the fiber optic gyroscope optical path system, and determine the optimal modulation depth of the current optical power based on the relationship between the optimal modulation depth and the step height.

[0079] The specific implementation process of step S2 is explained below.

[0080] Step S21: Amplify and convert the optical interference signal to digital to generate a digital interference signal.

[0081] Step S22: Decompose the digital interference signal into the demodulation rate signal and the demodulation optical power signal.

[0082] Step S23: Perform additional interference demodulation on the optical power signal to be demodulated to obtain the demodulated amount of optical power; and obtain the optimal modulation depth corresponding to the current optical power based on the relationship between the optimal modulation depth and the step height.

[0083] Step S3: Generate an analog modulation signal based on the optimal modulation depth of the optical power and the additional modulation signal.

[0084] Step S31: Demodulate 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; integrate the closed-loop feedback step signal to generate a stepped wave signal.

[0085] Step S32: Generate the corresponding normal modulation signal based on the optimal modulation depth.

[0086] Step S33: Superimpose the generated stepped wave signal, the normal modulation signal, and the additional modulation signal to obtain the digital modulation signal.

[0087] Step S34: Perform digital-to-analog conversion and signal amplification on the digital modulation signal to generate an analog modulation signal.

[0088] Step S4: Input the analog modulation signal into the fiber optic gyroscope optical path system to achieve precision control of the fiber optic gyroscope.

[0089] Specific embodiment 2 of the present invention also discloses a modulation and demodulation system for maintaining the precision of a fiber optic gyroscope. This system is based on the precision maintenance method based on adaptive adjustment of the modulation depth of the fiber optic gyroscope in embodiment 1. A schematic diagram of the system structure is shown below. Figure 3 As shown, this modulation and demodulation system includes a fiber optic gyroscope optical path subsystem, a signal processing and conversion subsystem, and a modulation and demodulation subsystem. The following sections provide a detailed description of each subsystem.

[0090] (1) Fiber Optic Gyroscope Optical Circuit Subsystem

[0091] The fiber optic gyroscope optical path subsystem (i.e., the fiber optic gyroscope optical path system in Example 1) is used to output optical interference signals to the signal processing and conversion subsystem in real time; it is also used to receive analog modulation signals output by the modulation and demodulation subsystem in real time and perform real-time phase modulation on the fiber optic gyroscope.

[0092] In this embodiment, the fiber optic gyroscope optical path subsystem consists of a light source, a coupler, a fiber optic ring, an integrated optical modulator, and a photodetector, and is capable of realizing the Sagnac effect of the fiber optic gyroscope.

[0093] In the specific operation, the light source generates a stable optical signal, which serves as the basis for subsequent interference and modulation. The coupler splits the optical signal into two beams, propagating clockwise and counterclockwise along the fiber optic loop, respectively. As the fiber loop rotates, the two beams experience an optical path difference due to the rotation, forming a Sagnac phase difference, which is the core manifestation of the Sagnac effect. The integrated optical modulator modulates the two beams in real time based on the received analog modulation signal. The modulated signal is superimposed on the Sagnac phase difference, facilitating subsequent signal processing. The two modulated optical signals interfere at the coupler, and the intensity change of the interference signal reflects the combined effect of the Sagnac phase difference and the modulation phase. The photodetector converts the interfering optical signal into an electrical signal, outputting an optical power signal (i.e., the interference signal) related to the interference intensity. This signal contains information about the Sagnac effect and is used for subsequent demodulation and calculation of the rotational angular velocity. Therefore, the optical interference signal is output by the photodetector, and the analog modulation signal is applied to the integrated optical modulator.

[0094] (2) Signal Processing and Conversion Subsystem

[0095] The signal processing and conversion subsystem is used to process the interference signal, generate a digital interference signal, and input it into the modulation and demodulation subsystem.

[0096] Specifically, in this embodiment, the signal processing and conversion subsystem can be implemented using a preamplifier and analog-to-digital converter circuit 2.

[0097] The preamplifier and analog-to-digital converter circuit 2 is used to amplify and convert the optical interference signal (i.e., the electrical signal converted by the photodetector) to generate a digital interference signal, which is then input into the demodulation information classification module in the modulation and demodulation subsystem.

[0098] (3) Modulation and demodulation subsystem

[0099] The modulation and demodulation subsystem is used to perform rate demodulation and additional interference demodulation based on the digital interference signal, and to superimpose the step wave signal obtained by rate demodulation, the normal modulation signal obtained by additional interference demodulation, and the additional modulation signal to obtain a digital modulation signal; and to perform signal processing on the digital modulation signal to generate the analog modulation signal.

[0100] The modulation and demodulation subsystem includes a demodulation information classification module 3, a rate information demodulation module 4, a stepped 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 converter and subsequent amplifier circuit 11. The functions of each component are described in detail below.

[0101] 1) Demodulation information classification module 3

[0102] The demodulation information classification module 3 is used to decompose the digital interference signal into the demodulation rate signal and the demodulation optical power signal, and input the demodulation rate signal and the demodulation optical power signal into the rate information demodulation module 4 and the optical power information demodulation module 6, respectively.

[0103] In the specific implementation process, the demodulation information classification module 3 can decompose the digital interference signal according to the preset control timing sequence.

[0104] 2) Rate information demodulation module 4

[0105] The rate information demodulation module 4 is used to demodulate the rate signal to be demodulated and generate a closed-loop feedback step signal corresponding to the rate information of the rate signal to be demodulated; the closed-loop feedback step signal is input into the step wave signal generation module 5.

[0106] In practice, the demodulation rate signal can be demodulated according to the demodulation timing sequence.

[0107] 3) Step wave signal generation module 5

[0108] Step wave signal generation module 5 is used to integrate the closed-loop feedback step signal to generate a step wave signal.

[0109] 4) Optical power information demodulation module 6

[0110] The optical power information demodulation module 6 is used to perform additional interference demodulation on the optical power signal to be demodulated to obtain the demodulated amount of optical power; and inputs the demodulated amount of optical power into the modulation depth adjustment module 7.

[0111] Specifically, the optical power information demodulation module 6 demodulates the optical power signal to be demodulated by: demodulating the digital signal amplitude C1 with and without additional interference signals from the optical power signal to be demodulated; calculating the step height ΔC = C1 - C2 according to the formula; and using the step height ΔC as the demodulated amount of optical power. Further details will follow. Figure 2 and Figure 3 The handling method here will be further explained.

[0112] In the specific implementation process, the demodulation information classification module 3 extracts the optical power signal to be demodulated according to the application timing of the additional modulation signal and sends it to the optical power information demodulation module 6.

[0113] 5) Modulation depth adjustment module 7

[0114] The modulation depth adjustment module 7 is used to determine the optimal modulation depth corresponding to the current optical power based on the demodulation amount of the optical power; and input the optimal modulation depth into the normal modulation signal generation module 8.

[0115] In the specific implementation process, this embodiment uses the pre-established relationship between the step height ΔC (i.e. the demodulation amount of the optical power signal to be demodulated) and the optimal modulation depth (digital quantity) to obtain the optimal modulation depth corresponding to the current optical power based on the demodulation amount of the optical power signal to be demodulated, i.e. the optimal modulation depth corresponding to the modulation signal to be applied, so as to optimize the accuracy of the fiber optic gyroscope.

[0116] 6) Normal modulation signal generation module 8

[0117] Normal modulation signal generation module 8 is used to generate the corresponding normal modulation signal according to the optimal modulation depth.

[0118] In some embodiments, the normal modulation mode generated by the normal modulation signal generation module 8 can be four-state modulation, square wave modulation, or a hybrid modulation mode. The optimal modulation depth is used as the modulation phase of the normal modulation signal, and a corresponding normal modulation signal is generated according to the normal modulation mode of the gyroscope.

[0119] The normal modulation signal generation module 8 receives the optimal modulation depth output by the modulation depth adjustment module 7 and changes the current gyroscope modulation depth to the optimal modulation depth, thereby achieving modulation phase adjustment of the fiber optic gyroscope and making the gyroscope's accuracy optimal.

[0120] 7) Additional modulation signal generation module 9

[0121] Additional modulation signal generation module 9 is used to periodically output additional modulation signals.

[0122] 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, N can be very large.

[0123] Within 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 π / M, and the amplitude of the additional interference signal in the second τ is -π / M, where M is a positive integer.

[0124] 8) Modulation signal combination module 10

[0125] The modulation signal combination module 10 is used to superimpose the stepped wave signal, the normal modulation signal and the additional modulation signal to generate a digital modulation signal.

[0126] In the specific implementation process, the stepped wave signal output by the stepped wave signal generation module 5, the normal modulation signal output by the normal modulation signal generation module 8, and the additional modulation signal generated by the additional modulation signal generation module 9 are synchronously superimposed in the modulation signal combination module 10 with a transit time τ as the period.

[0127] The advantage of this modulation method is that it combines the modulation signals required for the normal operation of the fiber optic gyroscope—namely, the normal modulation signal and the step-wave signal—while also accommodating the additional modulation signal used for accuracy maintenance. This modulation method can operate without affecting the normal operation of the fiber optic gyroscope, while simultaneously generating the optical power to be demodulated at the demodulation end due to the additional modulation signal, which is used to demodulate the optical power.

[0128] The periodic additional modulation signal enables the integrated optical modulator to generate periodic additional phase modulation, which acts on the optical interference signal of the fiber optic gyroscope optical circuit subsystem and generates a periodic additional step digital signal (i.e., the optical power signal to be demodulated) through the pre-amplifier and analog-to-digital converter circuit 2.

[0129] 9) Post-amplifier and digital-to-analog converter circuit 11

[0130] The post-amplifier and digital-to-analog converter circuit 11 is used to perform digital-to-analog conversion and signal amplification on the digital modulation signal to generate the corresponding analog modulation signal.

[0131] The analog modulation signal is input to the integrated optical modulator in the fiber optic gyroscope optical path subsystem to achieve phase modulation of the fiber optic gyroscope.

[0132] This embodiment, through the above modulation and demodulation method, ultimately achieves real-time monitoring of changes in gyroscope optical power and adjusts the modulation depth of the gyroscope online according to the changes in optical power, so that the accuracy of the fiber optic gyroscope is maintained at the optimal value under the current optical power, thus achieving the accuracy maintenance of the fiber optic gyroscope.

[0133] In this embodiment, the generated digital modulation signal can achieve rate information demodulation output and modulation phase feedback generation.

[0134] Figure 4 This is a schematic diagram of a stepped wave modulated signal, a normal modulated signal, and an additional modulated signal.

[0135] Figure 5 This is a schematic diagram of the optical power signal to be demodulated.

[0136] It should be noted that, in this embodiment, the demodulation amount of optical power is... Figure 5 The step height ΔC is given by the additional modulation signal, which carries a periodic additional interference signal (i.e., additional step digital information). The step height ΔC is proportional to the current optical power amplitude. Without the additional interference signal, the digital signal amplitude is C1; with the additional interference signal, the digital signal amplitude is C2. (Refer to...) Figure 5 Part B1 is due to the application of Figure 4 The response signal generated by the additional modulation signal shown is represented by the combination of B1 and A, which is the optical power signal to be demodulated, and the combination of B and A is the rate signal to be demodulated. When an additional modulation signal is applied... Figure 4 The additional modulation signal shown will inevitably produce Figure 5 The A1 and B1 signals in the optical power demodulation module 6 generate the optical power signal to be demodulated. During the demodulation process of the optical power information demodulation module 6, the corresponding signals in two adjacent demodulation cycles are subtracted. The amplitude of the digital signal without additional interference signal is C1, and the amplitude of the digital signal with additional interference signal is C2. The step height ΔC is obtained by subtracting the two signals.

[0137] As can be seen from the above description, the main improvements of the accuracy preservation method based on adaptive adjustment of fiber optic gyroscope modulation depth provided in this embodiment include:

[0138] 1. Core Innovation: Based on real-time detection of changes in the optical power of the fiber optic gyroscope, and using an established fitting function relationship between optical power and modulation depth, the optimal modulation depth is calculated internally by software algorithms within the gyroscope and adjusted in a timely manner. This ensures that the gyroscope's accuracy remains at the optimal level corresponding to the current optical power. The entire implementation process does not require changes to the gyroscope's optical path, circuitry, or other hardware, making it easy to implement and promote.

[0139] 2. Secondary innovation point 1: By using an additional modulation method with a duration of 2τ and a signal amplitude of ±π / M (M is a positive integer), an additional interference signal is formed, and the real-time monitoring of the gyroscope optical power change is achieved by using a demodulation method corresponding to the timing of the modulation signal.

[0140] 3. Secondary innovation point 2: Based on the calculation method of RWC of fiber optic gyroscope, a fitting method for the optical power of fiber optic gyroscope and the optimal modulation depth is established. This method is easy to implement in the software algorithm chip FPGA used in mainstream fiber optic gyroscopes.

[0141] 4. Secondary Innovation Point 3: This scheme offers high precision in modulation depth adjustment, reaching [amount missing]. N represents the number of bits in the digital-to-analog converter.

[0142] This embodiment improves the dynamic performance of the fiber optic gyroscope by setting the period of the additional modulation signal to 2Nτ and by rapidly demodulating and processing the optical power and rate signals to be demodulated. This rapid response capability is crucial for the fiber optic gyroscope to maintain high-precision measurements in high-speed or rapidly changing environments, better meeting the dynamic performance requirements of modern navigation systems and effectively enhancing the dynamic performance of the fiber optic gyroscope.

[0143] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A precision maintenance method based on modulation depth adaptive adjustment of an optical fiber gyroscope, characterized by, The method comprises: constructing the relationship between the optimal modulation depth and the step height; obtaining the optical interference signal output by the fiber-optic gyroscope optical system in real time, and determining the optimal modulation depth of the current optical power according to the relationship between the optimal modulation depth and the step height; generating the analog modulation signal based on the optimal modulation depth of the current optical power and the additional modulation signal; inputting the analog modulation signal into the fiber-optic gyroscope optical system to realize precision maintenance control of the fiber-optic gyroscope.

2. The precision maintaining method based on modulation depth self-adaptive adjustment of the fiber-optic gyroscope according to claim 1, characterized in that, The construction of the relationship between the optimal modulation depth and the step height comprises: constructing the curve relationship between the optical power of the fiber-optic gyroscope and the optimal modulation depth; constructing the relationship between the optimal modulation depth and the step height according to the curve relationship between the optical power of the fiber-optic gyroscope and the optimal modulation depth.

3. The precision maintaining method based on modulation depth self-adaptive adjustment of the fiber optic gyroscope according to claim 2, characterized in that, The construction of the curve relationship between the optical power of the fiber-optic gyroscope and the optimal modulation depth comprises: setting multiple optical power points at a fixed power interval; and setting multiple modulation depths at a fixed modulation depth interval under each optical power point; for each optical power point, calculating the 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 relationship between the optical power and the optimal modulation depth according to each optical power point and the corresponding optimal modulation depth, and establishing the curve relationship between the optical power and the optimal modulation depth.

4. The precision maintaining method based on modulation depth self-adaptive adjustment of the fiber optic gyroscope according to claim 3, characterized in that, The relationship between the optical power and the optimal modulation depth is fitted by selecting a binary quadratic equation; in the fitting process, the quadratic fitting parameters a0, a1, and a2 are determined; and a quadratic fitting curve relationship between the optical power and the optimal modulation depth is established, which is expressed as: Φ 0i = a0+ a1P 0i + a2P 0i 2 (3) where P 0i represents the optical power, Φ 0i represents the optimal modulation depth corresponding to the current optical power.

5. The precision maintaining method based on modulation depth self-adaptive adjustment of the fiber-optic gyroscope according to claim 4, characterized in that, the relationship between the optimal modulation depth and the step height is expressed as: Φ 0i = b0+ b1AC i + b2AC i 2 (1) where ΔC i represents the step height, Φ 0i represents the optimal modulation depth; b0=a0, b1=a1 / K, b2=a2 / K, K=P 0i / ΔC i .

6. The precision maintaining method based on modulation depth self-adaptive adjustment of fiber optic gyroscope according to any one of claims 1-5, characterized in that, The determination of the optimal modulation depth of the current optical power according to the relationship between the optimal modulation depth and the step height comprises: 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 to-be-demodulated rate signal and a to-be-demodulated optical power signal; performing additional interference demodulation on the to-be-demodulated optical power signal to obtain a demodulation amount of the optical power; and obtaining the optimal modulation depth corresponding to the current optical power according to the relationship between the optimal modulation depth and the step height.

7. The precision maintaining method based on modulation depth self-adaptive adjustment of the fiber-optic gyroscope according to claim 6, characterized in that, The generation of the analog modulation signal comprises: generating a staircase wave signal according to the to-be-demodulated rate signal; generating a corresponding normal modulation signal according to the optimal modulation depth; superimposing the generated staircase wave signal, the normal modulation signal, and the additional modulation signal to obtain a digital modulation signal; performing digital-to-analog conversion and signal amplification on the digital modulation signal to generate the analog modulation signal.

8. The precision maintaining method based on modulation depth self-adaptive adjustment of the fiber-optic gyroscope according to claim 7, characterized in that, 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. In one period of the additional modulation signal, the duration of the additional interference signal is 2τ. The demodulation of the to-be-demodulated optical power signal to obtain the demodulation amount of the optical power comprises:

9. The precision maintaining method based on modulation depth self-adaptive adjustment of the fiber-optic gyroscope according to claim 8, wherein, demodulating the digital signal amplitude C1 when the additional interference signal is present and the digital signal amplitude C2 when the additional interference signal is not present from the to-be-demodulated optical power signal; calculating the step height ΔC = C1-C2 according to the formula, and taking the step height ΔC as the demodulation amount of the optical power. ​ 10. The precision maintaining method based on modulation depth self-adaptive adjustment of the fiber-optic gyroscope according to claim 9, wherein, The step wave signal is generated according to the to-be-demodulated rate signal, and the following is performed: rate demodulation is performed on the to-be-demodulated rate signal to generate a closed-loop feedback step signal corresponding to rate information of the to-be-demodulated rate signal; integration is performed on the closed-loop feedback step signal to generate the step wave signal.

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