A small inertial navigation gyroscope inter-axis crosstalk suppression method and system

Abstract

The application provides a small inertial navigation gyroscope inter-axis crosstalk suppression method and system, and the method comprises the following steps: obtaining eigen-demodulation frequency of a target multiplexed fiber optic gyroscope, and determining a phase-sensitive demodulation reference benchmark of a working axis; for a non-working axis in a non-working state, a symmetric conical modulation phase sequence which is not homologous to the eigen-demodulation frequency is generated; the modulation fundamental frequency of the symmetric conical modulation phase sequence has a preset frequency difference, so that the fundamental frequencies of residual light intensity crosstalk and peak crosstalk output by the non-working axis all have a non-zero frequency difference; the symmetric conical modulation phase sequence is loaded to a phase modulator of the non-working axis, and phase modulation is performed on the non-working axis. The application can increase the difference between the fundamental frequencies of residual light intensity and peak crosstalk and the eigen-demodulation frequency through the symmetric conical modulation phase sequence, so as to suppress the residual light intensity and peak crosstalk and improve the accuracy of relevant detection.

Description

Technical Field

[0001] This invention relates to the field of fiber optic gyroscope technology, and more specifically to a method and system for suppressing inter-axis crosstalk in a small inertial gyroscope. Background Technology

[0002] Fiber optic gyroscopes, due to their outstanding advantages such as short startup time, fast response speed, all-solid-state structure, low cost, long lifespan, large dynamic range, and low noise, have been widely used in various navigation and control equipment across land, sea, air, and space. Among them, three-axis time-division multiplexed fiber optic gyroscopes, by allowing the three axes to share the same core components such as light source, detector, and signal processing circuitry in different time slots, can significantly reduce the mass, size, power consumption, and manufacturing cost of the gyroscope system. Therefore, multiplexed fiber optic gyroscopes are an important choice for low-cost, lightweight inertial navigation systems. Furthermore, as miniaturized guidance devices and other equipment continue to develop towards lighter weight and lower cost, the application demand for three-axis time-division multiplexed fiber optic gyroscopes continues to increase.

[0003] In existing conventional modulation schemes for multiplexed fiber optic gyroscopes, to improve detection sensitivity and signal-to-noise ratio, the working axis is modulated to [a specific modulation scheme] within a single time-division duty cycle. The optimal bias phase is obtained, while modulating the non-working axis to... Phase modulation, by suppressing the return light from the non-working axis into dark interference fringes, significantly reduces the light intensity interference of the non-working axis on the working axis. However, in engineering practice, the half-wave voltage of the fiber optic gyroscope phase modulator is susceptible to drift due to environmental factors such as temperature. Existing solutions typically achieve matching of the modulation voltage with the ideal phase by adding a closed-loop gain adjustment channel. However, in low-speed input scenarios, this closed-loop channel is prone to second-loop failure due to the reduced number of phase resets, resulting in the modulation phase of the non-working axis failing to maintain the ideal phase. This generates bias modulation phase error. The actual modulation phase becomes .like Figure 1 As shown, at this time, the non-working axis is equivalent to a fiber optic gyroscope modulated in an open-loop state, which can be sensitive to the input rotation speed (square wave in the figure). Moreover, the interference signal is at the same frequency as the demodulated signal of the working axis. After being received by the detector and detected by phase sensitivity, it enters the closed-loop system and interferes with the detection result of the working axis, i.e., residual light intensity crosstalk.

[0004] Meanwhile, the spike signal of the fiber optic gyroscope detector originates from the retrace process of the square wave signal of the phase modulator. Ideally, the spectrum of the spike signal is distributed at even multiples of the intrinsic frequency, which is in the low-sensitivity frequency domain of the fiber optic gyroscope and will not affect the gyroscope's performance. In reality, due to the limitations of the detection bandwidth and output amplitude of devices such as the detector, preamplifier circuit, and ADC, the actual spike signal will be distorted or saturated. Furthermore, in a multi-axis multiplexed system, the spike signal reaching the detector is the superposition of spikes from all axes, significantly increasing the total signal amplitude. Figure 2 and Figure 3 As shown, when the X-axis is in the working state and the Y-axis is in the non-working state, the peak signal waveform of the detector and the peak signal amplitude of the multiplexing system are significantly increased, which is the sum of the peak signals of the X and Y axes. This forms the peak crosstalk of the multiplexed gyroscope.

[0005] Therefore, residual light intensity crosstalk and spike crosstalk are among the main error sources affecting the performance of multiplexed fiber optic gyroscopes. From the perspective of improving the accuracy of navigation systems, it is necessary to address the error sources of inter-axis crosstalk. Summary of the Invention

[0006] In view of the above problems, embodiments of the present invention provide a method and system for suppressing inter-axis crosstalk in a small inertial gyroscope to solve the existing technical problems.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for suppressing inter-axis crosstalk in a small inertial gyroscope, the method comprising the following steps: Acquire the intrinsic demodulation frequency of the target multiplexed fiber optic gyroscope. Determine the phase-sensitive demodulation reference standard for the working axis; For non-operating axes in non-operating states, generate intrinsic demodulation frequencies. Non-homogeneous symmetrical tapered modulation phase sequences; the modulation fundamental frequency of the symmetrical tapered modulation phase sequence and There is a preset frequency difference to ensure that the fundamental frequency of residual light intensity crosstalk and spike crosstalk in the non-working axis output is the same as that in the non-working axis output. There is a non-zero frequency difference; A symmetrical tapered modulation phase sequence is loaded onto the phase modulator of the non-working axis to perform phase modulation on the non-working axis.

[0008] In one embodiment, the symmetrical cone modulation phase sequence is a symmetrical phase sequence in which the phase first increases linearly and then decreases linearly within a single period, and the phase step value of the sequence is constant.

[0009] In one embodiment, the phase step value of the sequence is always 1. .

[0010] In one embodiment, the single-cycle duration of the symmetrical cone-modulated phase sequence is 6. ,in This is the transit time of light within the fiber optic loop of the fiber optic gyroscope.

[0011] In one embodiment, the single-cycle phases of the symmetrical tapered modulation phase sequence are sequentially as follows: , The fundamental frequency of the residual optical intensity crosstalk at the non-working axis output is The fundamental frequency of the spike crosstalk is .

[0012] In a second aspect, the present invention provides a small inertial gyroscope inter-axis crosstalk suppression system, the system comprising: The parameter acquisition module is used to acquire the intrinsic demodulation frequency of the target multiplexed fiber optic gyroscope. Determine the phase-sensitive demodulation reference standard for the working axis; The modulation sequence generation module is used to generate the intrinsic demodulation frequency for the non-working axis in the non-working state. Non-homogeneous symmetrical tapered modulation phase sequences; the modulation fundamental frequency of the symmetrical tapered modulation phase sequence and There is a preset frequency difference to ensure that the fundamental frequency of residual light intensity crosstalk and spike crosstalk in the non-working axis output is the same as that in the non-working axis output. There is a non-zero frequency difference; The modulation execution module is used to load a symmetrical tapered modulation phase sequence onto the phase modulator of the non-working axis and perform phase modulation on the non-working axis.

[0013] In one embodiment, the symmetrical cone modulation phase sequence is a symmetrical phase sequence in which the phase first increases linearly and then decreases linearly within a single period, and the phase step value of the sequence is constant.

[0014] In one embodiment, the phase step value of the sequence is always 1. .

[0015] In one embodiment, the single-cycle duration of the symmetrical cone-modulated phase sequence is 6. ,in This is the transit time of light within the fiber optic loop of the fiber optic gyroscope.

[0016] In one embodiment, the single-cycle phases of the symmetrical tapered modulation phase sequence are sequentially as follows: , The fundamental frequency of the residual optical intensity crosstalk at the non-working axis output is The fundamental frequency of the spike crosstalk is .

[0017] Compared with the prior art, the beneficial effects of this application are as follows: This invention modulates the phase sequence with a symmetrical cone only on the non-working axis, while simultaneously ensuring that the residual light intensity crosstalk fundamental frequency and the spike crosstalk fundamental frequency on the non-working axis are both the same as the demodulation frequency on the working axis. The presence of a non-zero difference eliminates co-frequency crosstalk components. Subsequent low-pass filtering completely removes residual light intensity and spike crosstalk, thereby improving the detection accuracy of the multiplexed fiber optic gyroscope. Furthermore, this symmetrical conical modulation method is unaffected by half-wave voltage drift caused by temperature changes, nor by the failure of the closed-loop gain adjustment channel in low-speed input scenarios. Even with modulation phase errors, the crosstalk components maintain a fixed difference from the demodulation frequency, allowing for stable filtering by the low-pass filter, significantly improving the stability of the fiber optic gyroscope's detection accuracy in complex environments. Attached Figure Description

[0018] Figure 1 The diagram shows a non-working axis square wave modulation and detector response in the prior art. Figure 2 The diagram shows a schematic of the detector spike signal when operating on a single axis in the prior art. Figure 3 The diagram shows a schematic of the detector spike signal when operating on two axes (X and Y axes) in the prior art. Figure 4 The diagram shown is a flowchart illustrating a method for suppressing inter-axis crosstalk in a small inertial gyroscope according to an embodiment of the present invention. Figure 5 The diagram shown is a schematic representation of a method for suppressing inter-axis crosstalk in a small inertial gyroscope according to an embodiment of the present invention. Figure 6 The diagram shown is a structural schematic of a small inertial gyroscope interaxial crosstalk suppression system according to an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer and more understandable, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0020] To address the shortcomings of existing technologies, this invention provides a specific implementation method for suppressing inter-axis crosstalk in small inertial gyroscopes, such as... Figure 4 and combined Figure 5 As shown, the method specifically includes: S110: Obtain the intrinsic demodulation frequency of the target multiplexed fiber optic gyroscope. Determine the phase-sensitive demodulation reference standard for the working axis.

[0021] Multiplexed fiber optic gyroscopes can be triaxial multiplexed fiber optic gyroscopes, where the three axes alternately operate at different times, sharing a single light source, detector, and signal processing circuit. The fiber optic loop transit time of the fiber optic gyroscope is... The corresponding intrinsic demodulation frequency Intrinsic demodulation frequency The modulation frequency and phase-sensitive demodulation reference frequency of the working shaft are used within the working time slot. Bias phase modulation. For the optimal bias phase of the fiber optic gyroscope, the reference frequency for phase-sensitive demodulation is... The reason for this is... The reason why it is used as the modulation and demodulation reference for the working axis, rather than as the frequency isolation design reference for the non-working axis modulation sequence, is that this can provide a quantitative basis for the frequency isolation design of the non-working axis modulation sequence, ensuring that the subsequently generated modulation sequence can effectively distinguish between the crosstalk frequency and the demodulation frequency, and increasing the difference between the fundamental frequency and the intrinsic demodulation frequency of residual light intensity crosstalk and spike crosstalk.

[0022] S120: Generates the intrinsic demodulation frequency for non-operating axes in non-operating states. Non-homogeneous symmetrical tapered modulation phase sequences; the modulation fundamental frequency of the symmetrical tapered modulation phase sequence and There is a preset frequency difference to ensure that the fundamental frequency of residual light intensity crosstalk and spike crosstalk in the non-working axis output is the same as that in the non-working axis output. There is a non-zero frequency difference.

[0023] This symmetrical cone-modulated phase sequence is a symmetrical phase sequence with a phase that first increases linearly and then decreases linearly within a single period. The phase step value of the sequence is constant, and the phase step value of the sequence is always 1. .

[0024] The symmetrical tapered modulation sequence has a linear symmetrical structure and a constant phase step, which will not cause additional impact on optical devices on non-working axes, nor will it affect the normal modulation and demodulation process of the working axis.

[0025] The single-cycle duration of the symmetrical cone-modulated phase sequence is 6. ,in Let be the transit time of light within the fiber optic loop of the fiber optic gyroscope. Furthermore, the single-cycle phases of the symmetrical tapered modulation phase sequence are sequentially: , The fundamental frequency of the residual optical intensity crosstalk at the non-working axis output is The fundamental frequency of the spike crosstalk is .

[0026] like Figure 5 As shown, within a complete modulation cycle, the phase step value of the non-working axis phase modulator first linearly increases from 0 to 3π, then linearly decreases back to 0, exhibiting a symmetrical conical waveform. The symmetrical conical modulation sequence has a total of 7 phase points, corresponding to 6 phase steps of equal duration. The duration of each step is the transit time of the fiber loop. Therefore, the complete modulation period is 6. The single-cycle phases of the symmetrical cone-modulated phase sequence are as follows: The phase difference generated by this modulation method is The switching frequency is Substitute it into It can be converted to In an ideal state, the light intensity is always 0, but there is a phase error. When this happens, fluctuations occur, and the fundamental frequency of these fluctuations is... This refers to the fundamental frequency of residual light intensity crosstalk. The essence of a spike signal is a pulse signal generated by rapid light intensity retracement at the moment of phase transition. The repetition frequency of the spike is entirely determined by the period of the phase transition. The complete repetition period of the spike signal is the entire modulation period. Therefore, the fundamental frequency of the spike signal is Based on the frequency selectivity of phase-sensitive demodulation, the greater the frequency difference, the easier it is for the difference frequency component after crosstalk demodulation to be filtered out by the low-pass filter, thereby simultaneously suppressing the two error sources: residual light intensity crosstalk and spike crosstalk.

[0027] Compared to existing solutions that only achieve frequency shifting of residual optical intensity crosstalk, while peak crosstalk remains... Using the same frequency actually amplifies the effect of spike crosstalk. This embodiment, through the setting of a symmetrical conical modulation sequence, simultaneously achieves frequency shifting of residual intensity crosstalk and spike crosstalk, ensuring that the fundamental frequency of both crosstalks is the same as the frequency of the spike crosstalk. The existence of a fixed frequency difference eliminates the problem of crosstalk at the same frequency, providing a foundation for subsequent crosstalk filtering.

[0028] S130: Loads a symmetrical tapered modulation phase sequence onto the phase modulator of the non-working axis to perform phase modulation on the non-working axis.

[0029] In a system composed of three-axis multiplexed fiber optic gyroscopes, only one axis is the working axis within a single time interval, while the other two axes are non-working axes. Both non-working axes are loaded with the symmetrical conical modulation phase sequence. This allows modification of only the modulation waveform of the non-working axes without changing the modulation mechanism and multiplexing timing of the working axes, without requiring any changes to the existing system hardware or original workflow. This achieves crosstalk suppression while fully preserving the original performance advantages of the multiplexed fiber optic gyroscope.

[0030] After step S130 is completed, the process in step S120 can be achieved. The fundamental frequency of the residual optical intensity crosstalk at the non-working axis output is The fundamental frequency of the spike crosstalk is The goal is to ensure that the fundamental frequencies of both residual light intensity crosstalk and spike crosstalk are consistent with the intrinsic demodulation frequency. There are significant differences, but these significant differences in frequency can be suppressed by a low-pass filter during the correlation detection process, thereby reducing the influence of non-working axes on working axes and improving the accuracy of correlation detection.

[0031] Based on the same inventive concept, this application also provides a system that can be used to implement the methods described in the above embodiments, as described in the following embodiments. Since the principles and methods for solving the problem are similar, the implementation of the system can refer to the method implementation, and repeated details will not be repeated. As used below, the terms "unit" or "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the system described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0032] This invention provides a small inertial gyroscope inter-axis crosstalk suppression system, such as... Figure 6 As shown. In Figure 6 In this system, the following components are included: Parameter acquisition module 210 is used to acquire the intrinsic demodulation frequency of the target multiplexed fiber optic gyroscope. Determine the phase-sensitive demodulation reference standard for the working axis; Modulation sequence generation module 220 is used to generate the intrinsic demodulation frequency for a non-working axis in a non-working state. Non-homogeneous symmetrical tapered modulation phase sequences; the modulation fundamental frequency of the symmetrical tapered modulation phase sequence and There is a preset frequency difference to ensure that the fundamental frequency of residual light intensity crosstalk and spike crosstalk in the non-working axis output is the same as that in the non-working axis output. There is a non-zero frequency difference; The modulation execution module 230 is used to load a symmetrical tapered modulation phase sequence onto the phase modulator of the non-working axis and perform phase modulation on the non-working axis.

[0033] In one embodiment, the symmetrical cone modulation phase sequence is a symmetrical phase sequence in which the phase first increases linearly and then decreases linearly within a single period, and the phase step value of the sequence is constant.

[0034] In one embodiment, the phase step value of the sequence is always 1. .

[0035] In one embodiment, the single-cycle duration of the symmetrical cone-modulated phase sequence is 6. ,in This is the transit time of light within the fiber optic loop of the fiber optic gyroscope.

[0036] In one embodiment, the single-cycle phases of the symmetrical tapered modulation phase sequence are sequentially as follows: , The fundamental frequency of the residual optical intensity crosstalk at the non-working axis output is The fundamental frequency of the spike crosstalk is .

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for suppressing inter-axis crosstalk in a small inertial gyroscope, characterized in that, The method includes the following steps: Acquire the intrinsic demodulation frequency of the target multiplexed fiber optic gyroscope. Determine the phase-sensitive demodulation reference standard for the working axis; For non-operating axes in non-operating states, generate intrinsic demodulation frequencies. Non-homogeneous symmetrical tapered modulation phase sequences; the modulation fundamental frequency of the symmetrical tapered modulation phase sequence and There is a preset frequency difference to ensure that the fundamental frequency of residual light intensity crosstalk and spike crosstalk in the non-working axis output is the same as that in the non-working axis output. There is a non-zero frequency difference; A symmetrical tapered modulation phase sequence is loaded onto the phase modulator of the non-working axis to perform phase modulation on the non-working axis.

2. The method as described in claim 1, characterized in that, The symmetrical conical modulation phase sequence is a symmetrical phase sequence in which the phase first increases linearly and then decreases linearly within a single period, and the phase step value of the sequence is constant.

3. The method as described in claim 1, characterized in that, The phase step value of the sequence is always 1. .

4. The method as described in claim 1, characterized in that, The single-cycle duration of the symmetrical cone-modulated phase sequence is 6. ,in This is the transit time of light within the fiber optic loop of the fiber optic gyroscope.

5. The method as described in claim 1, characterized in that, The single-cycle phases of the symmetrical conical modulation phase sequence are as follows: The fundamental frequency of the residual light intensity crosstalk output from the non-working axis is [value missing]. The fundamental frequency of the spike crosstalk is .

6. A small inertial gyroscope inter-axis crosstalk suppression system, characterized in that, include: The parameter acquisition module is used to acquire the intrinsic demodulation frequency of the target multiplexed fiber optic gyroscope. Determine the phase-sensitive demodulation reference standard for the working axis; The modulation sequence generation module is used to generate the intrinsic demodulation frequency for the non-working axis in the non-working state. Non-homogeneous symmetrical tapered modulation phase sequences; the modulation fundamental frequency of the symmetrical tapered modulation phase sequence and There is a preset frequency difference to ensure that the fundamental frequency of residual light intensity crosstalk and spike crosstalk in the non-working axis output is the same as that in the non-working axis output. There is a non-zero frequency difference; The modulation execution module is used to load a symmetrical tapered modulation phase sequence onto the phase modulator of the non-working axis and perform phase modulation on the non-working axis.

7. The system as described in claim 5, characterized in that, The symmetrical conical modulation phase sequence is a symmetrical phase sequence in which the phase first increases linearly and then decreases linearly within a single period, and the phase step value of the sequence is constant.

8. The system as described in claim 5, characterized in that, The phase step value of the sequence is always 1. .

9. The system as described in claim 5, characterized in that, The single-cycle duration of the symmetrical cone-modulated phase sequence is 6. ,in This is the transit time of light within the fiber optic loop of the fiber optic gyroscope.

10. The system as described in claim 5, characterized in that, The term includes: The single-cycle phases of the symmetrical conical modulation phase sequence are as follows: The fundamental frequency of the residual light intensity crosstalk output from the non-working axis is [value missing]. The fundamental frequency of the spike crosstalk is .

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