A method for compensating scale factor error during the start-up process of a fiber optic gyroscope

Abstract

The present invention discloses a method for compensating a scale factor error in a fiber optic gyroscope startup process, and belongs to the technical field of fiber optic gyroscopes. The present invention takes into account that modern instruments usually require fiber optic gyroscopes to have high precision and short stabilization time; however, during the startup process, the generation of internal heat causes the fiber optic gyroscope temperature to rise, causing a scale factor error, affecting the performance of the fiber optic gyroscope, and limiting the application of the fiber optic gyroscope. Based on the startup process characteristics of the fiber optic gyroscope, the present invention proposes a scale factor error model for the startup process of the fiber optic gyroscope, and a method for identifying model parameters and compensating errors based on calibration experiments, thereby realizing real-time compensation for the scale factor error during the startup process. The present invention suppresses the scale factor error during the startup process of the fiber optic gyroscope, improves the dynamic measurement accuracy of the fiber optic gyroscope, and has certain engineering significance.

Description

Technical Field

[0001] The invention relates to the technical field of fiber optic gyroscopes, and mainly to a method for compensating a scale factor error in a fiber optic gyroscope startup process. Background Art

[0002] Fiber optic gyroscope is a new type of all-solid-state inertial instrument based on Sagnac effect. Fiber optic gyroscope has the advantages of large dynamic range, fast startup, long life, etc., and has been widely used in aerospace, robotic control and other fields. Modern instruments have higher and higher requirements on the accuracy of fiber optic gyroscopes, and the stability of fiber optic gyroscopes during the startup process is particularly important. The scale factor is usually used to characterize the dynamic performance of the fiber optic gyroscope, and its stability directly affects the accuracy of the fiber optic gyroscope. During the power-on startup of the fiber optic gyroscope, each optoelectronic device starts to work and generates heat, causing the temperature inside the fiber optic gyroscope to rise, thereby generating a scale factor error and reducing the accuracy of the fiber optic gyroscope. Therefore, it is necessary to model and compensate for the scale factor error of the fiber optic gyroscope during the startup process.

[0003] At present, the compensation of the scale factor error during the startup process is usually carried out by analyzing the change trend of the wavelength of the SLD light source during the startup process of the fiber optic gyroscope, taking certain measures to suppress the wavelength drift during the startup process, such as adding a temperature control device, establishing a wavelength startup model, etc., or by analyzing the scale factor error caused by the wavelength drift of the light source to compensate for it. These methods reduce the scale factor error to a certain extent. However, the scale factor error during the startup process of the fiber optic gyroscope is not only caused by the fluctuation of the light source during the startup process, but also related to factors such as the fiber ring change caused by the increase in the internal temperature of the fiber optic gyroscope and the change in the modulation coefficient of the feedback channel. It is difficult to achieve an ideal compensation effect by only considering the scale factor error caused by the light source fluctuation. Summary of the invention

[0004] The purpose of the present invention is to provide a method for compensating the scale factor error during the startup process of a fiber optic gyroscope. The method establishes a scale factor error model based on the startup characteristics of the fiber optic gyroscope, and implements a method for model parameter identification and error compensation based on a calibration experiment, thereby achieving real-time compensation for the scale factor error during the startup process.

[0005] In order to achieve the above object, the present invention provides a method for compensating a scale factor error in a fiber optic gyroscope startup process, comprising the following steps:

[0006] 1) Establish the scale factor error model of the fiber optic gyroscope during the startup process:

[0007] K=Ae BT

[0008] Wherein, K represents the scale factor of the fiber optic gyroscope, T represents the internal temperature of the fiber optic gyroscope, and A and B represent the model parameters related to temperature;

[0009] 2) Parameter identification of the scale factor error model of the fiber optic gyroscope;

[0010] 3) Real-time compensation for the scale factor error of the fiber optic gyroscope.

[0011] Furthermore, the step 2) is specifically as follows:

[0012] 2.1) In the operating temperature range of the fiber optic gyroscope [T min ,T max ] select W temperature points {T1, T2, ..., T i ,…,T W}, where T i represents the i-th test temperature point;

[0013] 2.2) At each test temperature point T i The calibration experiment of the fiber optic gyroscope is carried out under the following conditions: the fiber optic gyroscope is placed on a turntable with a temperature box, and the temperature of the temperature box is set to T i , the rotation speed of the turntable is ω, and after the internal temperature of the fiber optic gyroscope is consistent with the temperature of the incubator, the fiber optic gyroscope is powered on; the internal temperature T and the digital quantity D output by the fiber optic gyroscope during the startup process of the fiber optic gyroscope are collected;

[0014] 2.3) Calculate the scale factor of the fiber optic gyroscope:

[0015] K=D / ω

[0016] 2.4) Smoothing the collected internal temperature T during the startup of the fiber optic gyroscope and the calculated scale factor value K, and fitting the parameters of the scale factor error model in step 1) using the filtered data to obtain the scale factor error model K at each test temperature point T. i The corresponding model parameters A and B;

[0017] 2.5) Establish a multi-order formula:

[0018]

[0019]

[0020] Among them, A0 and B0 represent coefficients that are independent of temperature, a i 、b j represents the coefficient related to the initial temperature of the FOG, It represents the initial temperature of the FOG, that is, the temperature collected after the FOG is powered on; n and m represent the order of the model;

[0021] Using the A, B and test temperature point T obtained in step 2.4) i The initial temperature of the fiber optic gyroscope The established multi-order equation is fitted to obtain the multi-order equation parameters A0, B0, a i ,i=1,2,...,n、b j ,j=1,2,...,m.

[0022] Furthermore, the step 3) is specifically as follows:

[0023] 3.1) Real-time acquisition of the internal temperature of the fiber optic gyroscope during startup, and calculation of the real-time scaling factor based on the initial temperature at startup and the multi-order parameters obtained in step 2.5)

[0024]

[0025] 3.2) Correct the digital quantity output by the fiber optic gyroscope:

[0026]

[0027] Wherein, K0 is the standard value of the preset scale factor, D is the digital value output by the fiber optic gyroscope before correction, and D′ is the digital value output by the fiber optic gyroscope after correction.

[0028] Compared with the existing technology, the present invention has the following beneficial effects: the present invention establishes a scale factor error model based on the start-up characteristics of the fiber optic gyroscope, and implements a method for model parameter identification and error compensation according to a calibration experiment, thereby realizing real-time compensation for the scale factor error during the start-up process. The present invention suppresses the scale factor error during the start-up process of the fiber optic gyroscope, improves the dynamic measurement accuracy of the fiber optic gyroscope, and has certain engineering significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0030] Figure 1 It is a test system diagram, including: a turntable with a temperature box 1, a fiber optic gyroscope 2, a single-chip computer module 3, a temperature acquisition module 4, a fiber optic gyroscope data acquisition module 5, and a data correction module 6.

[0031] Figure 2 The present invention is a flowchart of a method for compensating a scale factor error in a fiber optic gyroscope startup process according to an embodiment of the present invention.

[0032] Figure 3 , Figure 4 , Figure 5The comparison diagrams of the scale factor errors before and after compensation when the fiber optic gyroscope is started at -40℃, 0℃, and 60℃ are shown in Figures (a) and (b) respectively. The scale factor errors before and after compensation are shown in Figures (a) and (b) respectively. DETAILED DESCRIPTION

[0033] In order to better illustrate the purpose and advantages of the present invention, the invention is further described below with reference to the accompanying drawings and examples.

[0034] Based on the characteristics of the start-up process of the fiber optic gyroscope, the present invention proposes a scale factor error model of the start-up process of the fiber optic gyroscope, and a method for identifying model parameters and compensating errors according to calibration experiments, thereby realizing real-time compensation of the scale factor error during the start-up process. The present invention suppresses the scale factor error during the start-up process of the fiber optic gyroscope, improves the dynamic measurement accuracy of the fiber optic gyroscope, and has certain engineering significance.

[0035] First, the rotation axis of the turntable 1 with a temperature box is set vertically, and the fiber optic gyroscope 2 is installed on the turntable 1 so that the oz axis is parallel to the rotation axis, and the turntable 1 with a temperature box, the fiber optic gyroscope 2 and the single-chip computer module 3 are connected. This system collects the temperature of the fiber optic gyroscope 2 through the temperature acquisition module 4, collects the digital quantity output by the fiber optic gyroscope 2 through the fiber optic gyroscope data acquisition module 5, and sends the data collected by the temperature acquisition module 4 and the fiber optic gyroscope data acquisition module 5 to the data correction module 6, thereby obtaining the digital quantity output by the fiber optic gyroscope after compensation.

[0036] A flow chart of a method for compensating the scale factor error during the start-up process of a fiber optic gyroscope is shown in FIG. Figure 2 As shown, the specific steps include:

[0037] (1) The operating temperature range of the fiber optic gyroscope is generally -40°C to 60°C. In this embodiment, six temperature points are selected within this temperature range, namely: -40°C, -20°C, 0°C, 20°C, 40°C, and 60°C. The fiber optic gyroscope is fixed on a turntable with a temperature chamber and the calibration experiment of the fiber optic gyroscope is completed in sequence at the above temperatures.

[0038] (2) The calibration experiment process of the fiber optic gyroscope is as follows: Set the temperature of the temperature box to T i , i=1,2,3,4,5,6; in this embodiment, T1=-40℃, T2=-20℃, T3=0℃, T4=20℃, T5=40℃, T6=60℃;

[0039] When the internal temperature of the fiber optic gyroscope is equal to the temperature T set in the temperature box iAfter maintaining consistency, the turntable is controlled to rotate at a uniform speed ω, the fiber optic gyroscope is powered on, and the digital quantity D output by the fiber optic gyroscope and the internal temperature T of the fiber optic gyroscope during the startup process (from initial startup to a period of stabilization) are collected; in this embodiment, ω=60° / s, and 100s of data are collected at each temperature point.

[0040] (3) The scale factor value of the fiber optic gyroscope is calculated according to K=D / ω, and the scale factor K of the fiber optic gyroscope and the temperature T inside the fiber optic gyroscope are smoothed respectively to remove the influence of noise; K and T are time series of equal length. In this embodiment, the two time series are smoothed for 10 seconds.

[0041] (4) Substitute the initial temperature of the FOG, the smoothed FOG scale factor, and the internal temperature of the FOG into the scale factor error model:

[0042] K=Ae BT

[0043] Wherein, K represents the scale factor of the fiber optic gyroscope, T represents the internal temperature of the fiber optic gyroscope, and A and B represent model parameters related to temperature. In this embodiment, the model coefficients A and B at different temperatures are as shown in Table 1 below:

[0044] Table 1:

[0045] -40℃ -20℃ 0℃ 20℃ 40℃ 60℃ A 172825034 172898507 172965434 173032352 173092822 173127434 B 6.68E-06 7.19E-06 6.64E-06 5.48E-06 4.75E-06 6.03E-06

[0046] The coefficients, A and B, are fitted in a multi-order form:

[0047]

[0048]

[0049] Among them, A0 and B0 represent coefficients that are independent of temperature, a i 、b j represents the coefficient related to the initial temperature of the FOG, It represents the initial temperature of the FOG, that is, the temperature collected after the FOG is powered on; n and m represent the order of the model.

[0050] In this embodiment, n=m=3 is taken, and a third-order polynomial is fitted using the data in Table 1:

[0051]

[0052]

[0053] The fitting parameters A0, B0, a1, a2, a3, b1, b2, and b3 can be obtained.

[0054] (5) Write the fitting parameters obtained in step (4) into the lower computer, which can be a single-chip microcomputer, DSP or FPGA, and let the temperature acquisition module collect the internal temperature of the fiber optic gyroscope in real time during the startup process. According to the collected initial temperature of the fiber optic gyroscope, combined with the fitting parameters, the A and B values ​​can be calculated and substituted into the scale factor error model K = Ae BT In the present invention, the scale factor K can be calculated based on the internal temperature of the fiber optic gyroscope collected in real time.

[0055] At the same time, the fiber optic gyro data acquisition module is used to collect the digital quantity D output by the fiber optic gyro. The compensation calculation module can calculate the digital quantity D′ output by the fiber optic gyro after compensation according to the scale factor error model. The calculation formula is:

[0056]

[0057] Wherein, K0 is the standard value of the scale factor, which is usually taken as the scale factor under the stable working state of the fiber optic gyroscope.

[0058] Figure 3 , Figure 4 , Figure 5 The scale factor error comparison diagrams before and after compensation when the fiber optic gyroscope is started at -40℃, 0℃, and 60℃ are shown respectively. Figures (a) and (b) are the scale factor errors before and after compensation, respectively. It can be seen that: this method reduces the mean value of the scale factor error when starting at -40℃ from 43.4ppm before compensation to 15.9ppm after compensation; reduces the mean value of the scale factor error when starting at 0℃ from 47ppm before compensation to 4.3ppm after compensation; reduces the mean value of the scale factor error when starting at 60℃ from 39.4ppm before compensation to 7.7ppm after compensation. The compensation results show that the present invention can well compensate for the scale factor error during the startup process of the fiber optic gyroscope, improve the accuracy of the fiber optic gyroscope, and has engineering application value.

[0059] The above examples are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples, and many variations are possible. All variations that can be directly derived or associated with the contents disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A method for compensating a scale factor error during a fiber optic gyroscope startup process, characterized in that: The following steps are involved: 1) Establish the scale factor error model of the fiber optic gyroscope during the startup process: K=Yes BT Wherein, K represents the scale factor of the FOG, T represents the internal temperature of the FOG, and A and B represent the model parameters related to temperature; 2) Parameter identification of the scale factor error model of the fiber optic gyroscope; the step 2) is specifically as follows: 2.1) In the operating temperature range of the fiber optic gyroscope [T min ,T max ] select W temperature points {T1, T2, ..., T i ,…,T W }, where T i represents the i-th test temperature point; 2.2) At each test temperature point T i The calibration experiment of the fiber optic gyroscope is carried out under the following conditions: the fiber optic gyroscope is placed on a turntable with a temperature box, and the temperature of the temperature box is set to T i , the rotation speed of the turntable is ω, and after the internal temperature of the fiber optic gyroscope is consistent with the temperature of the incubator, the fiber optic gyroscope is powered on; the internal temperature T and the digital quantity D output by the fiber optic gyroscope during the startup process of the fiber optic gyroscope are collected; 2.3) Calculate the scale factor of the fiber optic gyroscope: K=D / ω 2.4) Smoothing the collected internal temperature T during the startup of the fiber optic gyroscope and the calculated scale factor value K, and fitting the parameters of the scale factor error model in step 1) using the filtered data to obtain the scale factor error model K at each test temperature point T. i The corresponding model parameters A and B; 2.5) Establish a multi-order formula: Among them, A0 and B0 represent coefficients that are independent of temperature, a i 、b j represents the coefficient related to the initial temperature of the FOG, It represents the initial temperature of the FOG, that is, the temperature collected after the FOG is powered on; n and m represent the order of the model; Using the A, B and test temperature point T obtained in step 2.4) i The initial temperature of the fiber optic gyroscope The established multi-order equation is fitted to obtain the multi-order equation parameters A0, B0, a i ,i=1,2,...,n、b j ,j=1,2,...,m; 3) Real-time compensation for the scale factor error of the fiber optic gyroscope.

2. The method for compensating the scale factor error in the start-up process of the fiber optic gyroscope according to claim 1, characterized in that: The step 3) is specifically as follows: 3.1) Real-time acquisition of the internal temperature of the fiber optic gyroscope during startup, and calculation of the real-time scaling factor based on the initial temperature at startup and the multi-order parameters obtained in step 2.5) 3.2) Correct the digital quantity output by the fiber optic gyroscope: in, K0 is the standard value of the preset scale factor, D is the digital value output by the fiber optic gyroscope before correction, and D′ is the digital value output by the fiber optic gyroscope after correction.

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