Method for reducing nonlinearity of scale factor of large dynamic fiber-optic gyroscope

Abstract

The invention relates to the technical field of fiber-optic gyroscopes, in particular to a method for reducing the nonlinearity of a scale factor of a large dynamic fiber-optic gyroscope, which comprises the following steps of: setting different typical rates based on a measuring range required by an actual application scene of the fiber-optic gyroscope; electrifying the fiber-optic gyroscope, starting the single-axis rate turntable, rotating at a constant angular rate, and setting the rotating time as a fixed value; collecting pulse signals output by the single-shaft turntable and the fiber-optic gyroscope in real time; calculating corresponding angle drift errors of the fiber-optic gyroscope under the angular rate and the rotation time; dividing the whole angular rate range into a plurality of angular rate intervals, calculating a scale factor compensation value corresponding to each angular rate interval, performing correction, repeating the operation of obtaining the angle drift error, if the compensated angle drift error is still large, performing small-amplitude adjustment on the scale factor compensation value until the error is within a permissible range, and if the error is not within a permissible range, performing correction. According to the method, sectional compensation is carried out on the angular rate according to the size of the angle drift error, and the measurement precision of the large-dynamic fiber-optic gyroscope is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of fiber optic gyroscopes, and in particular to a method for reducing the nonlinearity of a scale factor of a large dynamic fiber optic gyroscope. Background Art

[0002] Fiber optic gyroscope is a fully solid-state angular rate sensor based on the Sagnac effect. Compared with traditional mechanical gyroscopes, it has a fully solid-state structure without rotating parts, and has outstanding advantages such as high sensitivity, large dynamic range, low energy consumption, strong impact resistance, small size, short start-up time, and long life. It has broad application prospects in military fields such as aviation, aerospace, and navigation, and civil fields such as intelligent robots and unmanned driving. In general, the larger the dynamic range of a fiber optic gyroscope, the lower its measurement accuracy. In some high-speed rotating navigation system applications, conventional fiber optic gyroscopes cannot meet the requirements of large dynamic range and measurement accuracy at the same time.

[0003] In order to improve the accuracy of large dynamic fiber optic gyroscopes, the paper "Research on segmented compensation technology for gyroscope errors in rate strapdown inertial navigation systems" demonstrated through simulation that segmented calibration of scale factors can improve gyroscope accuracy. The paper "Bilinear interpolation compensation model for scale factors of large dynamic fiber optic gyroscopes" proposed a method for comprehensive compensation of the temperature characteristics and nonlinearity of the scale factors of large dynamic fiber optic gyroscopes based on a bilinear interpolation model. The patent document "A method for full-temperature and full-dynamic pulse compensation of a large-range fiber optic gyroscope" discloses a method for comprehensive compensation of the temperature characteristics and nonlinearity of the scale factors of a fiber optic gyroscope by directly using the pulse output of a large-range fiber optic gyroscope.

[0004] However, these methods require a high-precision turntable for laboratory use, which can traverse the angular velocity within the entire range of the large dynamic fiber optic gyroscope and have high rate accuracy. However, the rate accuracy of the turntable is usually low at high rotation speeds (greater than 3000° / s), and the error of the scale factor of different angular rates of the fiber optic gyroscope is large when the dynamic range is large. Summary of the invention

[0005] The object of the present invention is to provide a method for reducing the nonlinearity of the scale factor of a large dynamic fiber optic gyroscope, aiming to solve the problem that the scale factor of different angular rates of the fiber optic gyroscope has large errors when the dynamic range is large.

[0006] To achieve the above object, the present invention provides a method for reducing the nonlinearity of the scale factor of a large dynamic fiber optic gyroscope, comprising the following steps:

[0007] Fix the fiber optic gyroscope on a single-axis rate turntable, with the test axis perpendicular to the turntable surface;

[0008] Based on the measuring range required by the actual application scenario of the fiber optic gyroscope, different typical speeds are set on the single-axis turntable control console;

[0009] The fiber optic gyroscope is powered on, and the single-axis rate turntable is started to rotate at a constant angular rate, and the rotation time is set to a fixed value;

[0010] The single-axis turntable works at an angular rate, and a collector is used to respectively collect pulse signals output by the single-axis turntable and the fiber optic gyroscope in real time;

[0011] After the rotation time reaches the fixed value, the single-axis turntable stops and the fiber optic gyroscope is powered off;

[0012] Based on the pulse signals output by the single-axis turntable and the fiber optic gyroscope, calculating the angle drift error of the fiber optic gyroscope corresponding to the angular velocity and the rotation time;

[0013] Based on the angle drift error, the entire angular velocity range is divided into several angular velocity intervals, and the scale factor compensation value corresponding to each angular velocity interval is calculated respectively, and correction is performed in the software. Then, the operation of obtaining the angle drift error is repeated. If the angle drift error after compensation is still too large, the scale factor compensation value is adjusted slightly until the compensated error is within the allowable range.

[0014] The actual application scenario of the fiber optic gyroscope requires a measurement range of 0° / s to 9000° / s.

[0015] Wherein, the measuring range accuracy of the single-axis turntable is 1.40625°.

[0016] Wherein, the angular rate is set to 9000° / s, 7200° / s, 5400° / s, 3600° / s, 1000° / s, 720° / s and 360° / s according to application requirements.

[0017] The calculation formula of the angle drift error is:

[0018]

[0019] Among them, t1 is the moment corresponding to the rising edge of the current pulse of the turntable output signal, T1 is the time width of the current pulse of the turntable output signal, t2 is the moment corresponding to the rising edge of the adjacent pulse of the gyroscope output signal, and T2 is the time width of the adjacent pulse of the gyroscope output signal.

[0020] The present invention provides a method for reducing the nonlinearity of the scale factor of a large dynamic fiber optic gyroscope. The fiber optic gyroscope is fixed on a single-axis rate turntable, and the test axis is perpendicular to the turntable surface; different typical rates are set on the single-axis turntable control console based on the range required by the actual application scenario of the fiber optic gyroscope; the fiber optic gyroscope is powered on, the single-axis rate turntable is started, and the fiber optic gyroscope rotates at a uniform speed at an angular rate, and the rotation time is set to a fixed value; the single-axis turntable works at the angular rate, and a collector is used to collect pulse signals output by the single-axis turntable and the fiber optic gyroscope in real time; after the rotation time reaches the fixed value, the single-axis turntable stops, and the fiber optic gyroscope is powered off; based on the pulse signals output by the single-axis turntable and the fiber optic gyroscope, the fiber optic gyroscope is calculated to measure the nonlinearity of the scale factor of the large dynamic fiber optic gyroscope under the angular rate and the rotation time. The corresponding angular drift error; based on the angular drift error, the entire angular velocity range is divided into several angular velocity intervals, and the scale factor compensation value corresponding to each angular velocity interval is calculated respectively, and the correction is performed in the software, and then the angle drift error operation is repeated. If the angle drift error after compensation is still too large, the scale factor compensation value is adjusted slightly until the compensated error is within the permissible range. This method converts the digital output of the turntable and the gyroscope into a pulse signal output, and has high accuracy under large dynamic conditions. The angular velocity is compensated in sections according to the size of the angular drift error, which greatly improves the measurement accuracy of the large dynamic fiber optic gyroscope. The angular measurement accuracy is high and reliable and stable, and the problem of large errors in scale factors of different angular rates of the fiber optic gyroscope under a large dynamic range is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram comparing the segmented scaling factor and the single scaling factor in the embodiment of the present invention.

[0023] Figure 2 It is a schematic diagram of the output pulse signals of the turntable and the gyroscope in the embodiment of the present invention.

[0024] Figure 3 The present invention provides a flowchart of a method for reducing the nonlinearity of the scale factor of a large dynamic fiber optic gyroscope.

[0025] Figure 4 The present invention provides a flow chart of a method for reducing the nonlinearity of a large dynamic fiber optic gyroscope scale factor. DETAILED DESCRIPTION

[0026] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0027] See also Figures 1 to 4 The present invention provides a method for reducing the nonlinearity of the scale factor of a large dynamic fiber optic gyroscope, comprising the following steps:

[0028] S1 fixes the fiber optic gyroscope on a single-axis rate turntable, with the test axis perpendicular to the turntable surface;

[0029] S2 sets different typical rates on the single-axis turntable control console based on the range required by the actual application scenario of the fiber optic gyroscope;

[0030] In the embodiment of the present invention, the actual application scenario of the fiber optic gyroscope requires a measurement range of 0° / s to 9000° / s, and different typical rates Ω are set. i (i=1,2,...,n), the measuring range accuracy of the single-axis turntable is 1.40625°.

[0031] S3: The fiber optic gyroscope is powered on, and the single-axis rate turntable is started to rotate at a constant angular rate, and the rotation time is set to a fixed value;

[0032] In the embodiment of the present invention, within 5 seconds after the fiber optic gyroscope is powered on, the single-axis rate turntable is started to rotate at an angular rate of Ω i The rotation time t0 is set to a fixed value for uniform rotation, which is convenient for comparison. In this embodiment, the rotation time t0 is set to 30s. The angular velocity is set to 9000° / s, 7200° / s, 5400° / s, 3600° / s, 1000° / s, 720° / s and 360° / s according to application requirements.

[0033] S4: the single-axis turntable works at an angular rate, and a collector is used to collect pulse signals output by the single-axis turntable and the fiber optic gyroscope in real time;

[0034] In the embodiment of the present invention, the output of the fiber optic gyroscope can be expressed as

[0035]

[0036] Where K(T,Ω) is the scale factor, which is proportional to the input angular velocity Ω i A function related to temperature T, is the inherent zero bias of the gyro. The scale factor error caused by the zero bias can be expressed as

[0037] ΔK=B0 / Ωi

[0038] Usually, the inherent zero bias of medium and high precision fiber optic gyroscope is less than 0.1° / h. From the above formula, it can be seen that when the gyroscope rotates at a high angular velocity, the error of the gyroscope output represents the change of the scale factor caused by temperature. At the same time, when the gyroscope works at the same temperature and rotates at a high angular velocity, the error of the gyroscope output represents the error of the scale factor caused by the rotation speed. Assuming that the temperature error of the scale factor has been compensated, the compensated scale factor error is only related to the input angular velocity, expressed as K(T0,Ω), where T0 is room temperature.

[0039] The output signals of the single-axis turntable and the fiber optic gyroscope are rectangular pulse signals, and a total of 128 pulses are output in one rotation. Each pulse includes a high level and a low level. The angles represented by the high and low level widths are 360 / 128 / 2=1.40625°, that is, the level is flipped every 1.40625° rotation.

[0040] S5: After the rotation time reaches the fixed value, the single-axis turntable stops and the fiber optic gyroscope is powered off;

[0041] S6: calculating the angle drift error of the fiber optic gyroscope corresponding to the angular velocity and the rotation time based on the pulse signal output by the single-axis turntable and the fiber optic gyroscope;

[0042] In the embodiment of the present invention, the angular velocity Ω of the fiber optic gyroscope is calculated based on the output data of the single-axis turntable and the fiber optic gyroscope. i And the angle drift error Δθ corresponding to the rotation time t0 i The pulse output of the single-axis turntable is achieved by fixing a gear with the same pitch and the number of teeth as 128 on a plane parallel to the table surface inside the turntable, and then hitting the gear with a grating. As the turntable rotates, the grating hits the top of the tooth and outputs a high level, and hits the root of the tooth and outputs a low level. Therefore, no matter how many degrees the turntable rotates, the angular accuracy can reach 1.40625°. The pulse output signal of the gyroscope is obtained by converting the digital quantity output by the gyroscope into a pulse level signal in the software. The specific method is to accumulate the digital quantity output by the gyroscope. When the accumulated value is greater than or equal to the digital quantity accumulated value P corresponding to 1.40625°, the gyroscope pulse level signal is flipped, and the accumulated value is subtracted from P to update, and this operation is repeated. The output angle drift error Δθ of the gyroscope can be expressed as

[0043]

[0044] Among them, t1 is the moment corresponding to the rising edge of the current pulse of the turntable output signal, T1 is the time width of the current pulse of the turntable output signal, t2 is the moment corresponding to the rising edge of the adjacent pulse of the gyroscope output signal, and T2 is the time width of the adjacent pulse of the gyroscope output signal.

[0045] S7 divides the entire angular velocity range into several angular velocity intervals based on the angular drift error, and calculates the scale factor compensation value corresponding to each angular velocity interval, respectively, makes corrections in the software, and then repeats the operation of obtaining the angle drift error. If the angle drift error after compensation is still too large, the scale factor compensation value is adjusted slightly until the compensated error is within the allowable range.

[0046] In the embodiment of the present invention, after a period of time, the temperature of the gyro is restored to room temperature, and steps S3, S4, S5, and S6 are repeated to obtain the gyro's input angular velocity Ω1, Ω2, ..., Ω n The corresponding angular drift errors are Δθ1, Δθ2, …, Δθ n , according to the angle drift error, the entire angular rate range is divided into m angular rate intervals p i (Ω),i=1,2,...,m;

[0047] In this embodiment, the obtained angle drift error before compensation is shown in Table 1, and is therefore divided into three angular rate intervals: p1(Ω)=[0~2300° / s), p2(Ω)=[2300~6300° / s), and p1(Ω)=[6300° / s~+∞].

[0048] Calculate the scale factor compensation value corresponding to each angular rate interval respectively, make corrections in the software, and then obtain the angle drift error operation to obtain the compensated angle drift error

[0049] Calculate the digital output of the fiber optic gyroscope according to the following formula:

[0050]

[0051] Where t0 is the turntable rotation time, and K0 is the scale factor measured according to the GJB 2426A-2004 method.

[0052] Then the angular velocity interval p i (Ω) J Ω1,Ω2,...,Ω J The corresponding output digital quantity D1, D2, ..., D J , substitute into formula D i =K i (T0,Ω)·Ω i , the least square method can be used to obtain each angular velocity interval p i (Ω) corresponds to the scaling factor K i (T0,Ω). If the angle drift error after compensation is still too large, the scale factor compensation value can be adjusted slightly until the error after compensation is within the permissible range.

[0053] Table 1 Comparison of angle drift error before and after scale factor nonlinearity compensation

[0054]

[0055] What is disclosed above is only a preferred embodiment of the method for reducing the nonlinearity of the scale factor of a large dynamic fiber optic gyroscope of the present invention. Of course, it cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for reducing the nonlinearity of the scale factor of a large dynamic fiber optic gyroscope, characterized in that: The following steps are involved: Fix the fiber optic gyroscope on a single-axis rate turntable, with the test axis perpendicular to the turntable surface; Based on the measuring range required by the actual application scenario of the fiber optic gyroscope, different typical speeds are set on the single-axis turntable control console; The fiber optic gyroscope is powered on, and the single-axis rate turntable is started to rotate at a constant angular rate, and the rotation time is set to a fixed value; The single-axis turntable works at an angular rate, and a collector is used to collect pulse signals output by the single-axis turntable and the fiber optic gyroscope in real time; After the rotation time reaches the fixed value, the single-axis turntable stops and the fiber optic gyroscope is powered off; Based on the pulse signals output by the single-axis turntable and the fiber optic gyroscope, calculating the angle drift error of the fiber optic gyroscope corresponding to the angular velocity and the rotation time; Based on the angle drift error, the entire angular velocity range is divided into several angular velocity intervals, and the scale factor compensation value corresponding to each angular velocity interval is calculated respectively, and correction is performed in the software. Then, the operation of obtaining the angle drift error is repeated. If the angle drift error after compensation is still too large, the scale factor compensation value is adjusted slightly until the compensated error is within the allowable range.

2. The method for reducing the nonlinearity of the scale factor of a large dynamic fiber optic gyroscope according to claim 1, It is characterized by: The measurement range required for the actual application scenario of the fiber optic gyroscope is 0° / s to 9000° / s.

3. The method for reducing the nonlinearity of the scale factor of a large dynamic fiber optic gyroscope according to claim 1, characterized in that ； The measuring range accuracy of the single-axis turntable is 1.40625°.

4. The method for reducing the nonlinearity of the scale factor of a large dynamic fiber optic gyroscope according to claim 1, characterized in that ； The angular rate is set to 9000° / s, 7200° / s, 5400° / s, 3600° / s, 1000° / s, 720° / s and 360° / s according to application requirements.

5. The method for reducing the nonlinearity of the scale factor of a large dynamic fiber optic gyroscope according to claim 1, characterized in that: The calculation formula of the angle drift error is: Among them, t1 is the moment corresponding to the rising edge of the current pulse of the turntable output signal, T1 is the time width of the current pulse of the turntable output signal, t2 is the moment corresponding to the rising edge of the adjacent pulse of the gyroscope output signal, and T2 is the time width of the adjacent pulse of the gyroscope output signal.

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