A method for reducing scale factor nonlinearity of a large dynamic fiber-optic gyroscope

Abstract

The present application relates to the technical field of fiber-optic gyroscope, and particularly relates to a method for reducing scale factor nonlinearity of large dynamic fiber-optic gyroscope, which comprises the following steps: setting different typical rates based on the range required by the actual application scene of the fiber-optic gyroscope; powering on the fiber-optic gyroscope and starting a single-axis rate turntable to rotate at a constant angular rate, and the rotation time is set as a fixed value; collecting the pulse signals output by the single-axis rate turntable and the fiber-optic gyroscope in real time; calculating the angular drift error of the fiber-optic gyroscope corresponding to the angular rate and the rotation time; dividing the entire angular rate range into several angular rate intervals, calculating the scale factor compensation value corresponding to each angular rate interval, and modifying it; repeating the operation of obtaining the angular drift error, if the compensated angular drift error is still large, then slightly adjusting the scale factor compensation value until the error is within the permitted range, the method performs segmented compensation on the angular rate according to the size of the angular drift error, and greatly improves the measurement accuracy of the large dynamic fiber-optic gyroscope.

Description

Technical Field

[0001] This invention relates to the field of fiber optic gyroscope technology, and in particular to a method for reducing the scaling factor nonlinearity of large dynamic fiber optic gyroscopes. Background Technology

[0002] Fiber optic gyroscopes are all-solid-state angular rate sensors based on the Sagnac effect. Compared to traditional mechanical gyroscopes, they feature an all-solid-state structure with no rotating parts, offering significant advantages such as high sensitivity, large dynamic range, low power consumption, strong shock resistance, small size, short startup time, and long lifespan. They have broad application prospects in military fields such as aviation, aerospace, and maritime applications, as well as civilian fields such as intelligent robotics and autonomous driving. Generally, 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 simultaneously meet the requirements of large dynamic range and measurement accuracy.

[0003] To improve the accuracy of large dynamic range fiber optic gyroscopes, the paper "Research on Segmented Error Compensation Technology for Rate Strapdown Inertial Navigation Systems" demonstrates through simulation that segmented scaling factor calibration can improve gyroscope accuracy. The paper "Bilinear Interpolation Compensation Model for Scale Factor of Large Dynamic Range Fiber Optic Gyroscopes" proposes a comprehensive compensation method for the temperature characteristics and nonlinearity of the scaling factor of large dynamic range fiber optic gyroscopes based on a bilinear interpolation model. The patent paper "A Full-Temperature, Full-Dynamic Pulse Compensation Method for Large-Range Fiber Optic Gyroscopes" discloses a method that directly utilizes the pulse output of a large-range fiber optic gyroscope to comprehensively compensate for the temperature characteristics and nonlinearity of the fiber optic gyroscope's scaling factor.

[0004] However, these methods require high-precision turntables used in laboratories to traverse the entire range of the large dynamic range fiber optic gyroscope and have high rate accuracy. In contrast, turntables typically have low rate accuracy at high speeds (greater than 3000° / s), and fiber optic gyroscopes have large scaling factor errors at different angular rates when the dynamic range is large. Summary of the Invention

[0005] The purpose of this invention is to provide a method for reducing the scaling factor nonlinearity of large dynamic range fiber optic gyroscopes, aiming to solve the problem of large scaling factor errors at different angular rates when fiber optic gyroscopes have a large dynamic range.

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

[0007] The fiber optic gyroscope is fixed on a single-axis rate turntable, with the test axis perpendicular to the turntable surface.

[0008] Based on the range required for the actual application scenario of the fiber optic gyroscope, different typical rates are set on the single-axis rate turntable control console.

[0009] When the fiber optic gyroscope is powered on, 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 rate turntable operates at an angular rate, and the pulse signals output by the single-axis rate turntable and the fiber optic gyroscope are collected in real time using a data acquisition instrument.

[0011] Once the rotation time reaches the fixed value, the single-axis rate turntable stops, and the fiber optic gyroscope is de-energized.

[0012] Based on the pulse signals output by the single-axis rate turntable and the fiber optic gyroscope, the angle drift error of the fiber optic gyroscope at the angular rate and rotation time is calculated.

[0013] Based on the angle drift error, the entire angular rate range is divided into several angular rate intervals, and the scaling factor compensation value corresponding to each angular rate interval is calculated and corrected in the software. The angle drift error operation is then repeated. If the compensated angle drift error is still too large, the scaling factor compensation value is adjusted slightly until the compensated error is within the permissible range.

[0014] The required measurement range for the actual application of the fiber optic gyroscope is 0. ~9000 .

[0015] The range accuracy of the single-axis rate turntable is 1.40625°.

[0016] The angular rate is set to 9000 according to application requirements. 7200 5400 3600 1000 720 and 360 .

[0017] The formula for calculating the angle drift error is as follows:

[0018]

[0019] in, This refers to the time corresponding to the rising edge of the current pulse of the turntable output signal. The time width of the current pulse of the turntable output signal. The gyroscope output signal corresponds to the time of the rising edge of an adjacent pulse. This refers to the time width of adjacent pulses in the gyroscope's output signal.

[0020] This invention discloses a method for reducing the scaling factor nonlinearity of a large dynamic range fiber optic gyroscope. The method involves fixing the fiber optic gyroscope on a single-axis rate turntable, with the test axis perpendicular to the turntable surface. Based on the measurement range required for the actual application scenario of the fiber optic gyroscope, different typical rates are set on the single-axis rate turntable control panel. The fiber optic gyroscope is powered on, and the single-axis rate turntable is started to rotate at a constant angular rate for a fixed rotation time. The single-axis rate turntable operates at the angular rate, and a data acquisition instrument is used to collect the pulse signals output by the single-axis rate turntable and the fiber optic gyroscope in real time. After the rotation time reaches the fixed value, the single-axis rate turntable stops, and the fiber optic gyroscope is powered off. Based on the pulse signals output by the single-axis rate turntable and the fiber optic gyroscope, the scaling factor nonlinearity of the fiber optic gyroscope is calculated. The angle drift error corresponding to the turn time is calculated. Based on the angle drift error, the entire angular rate range is divided into several angular rate intervals, and the scaling factor compensation value corresponding to each angular rate interval is calculated. The correction is performed in the software, and the angle drift error operation is repeated. If the angle drift error after compensation is still too large, the scaling factor compensation value is adjusted slightly until the compensation error is within the permissible range. This method converts the digital output of the turntable and gyroscope into pulse signal output, which has high accuracy under large dynamic conditions. The angular rate is compensated in segments according to the magnitude of the angle drift error, which greatly improves the measurement accuracy of the large dynamic fiber optic gyroscope. The angle measurement accuracy is high and reliable and stable, which solves the problem of large scaling factor error of different angular rates under large dynamic range of fiber optic gyroscope. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

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

[0024] Figure 3 This is a flowchart of a method for reducing the nonlinearity of the scaling factor in a large dynamic fiber optic gyroscope, provided by the present invention.

[0025] Figure 4 This is a flowchart of a method for reducing the nonlinearity of the scaling factor in a large dynamic fiber optic gyroscope, provided by the present invention. Detailed Implementation

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

[0027] Please see Figures 1 to 4 This invention provides a method for reducing the scaling factor nonlinearity of a large dynamic fiber optic gyroscope, comprising the following steps:

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

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

[0030] In this embodiment of the invention, the range required for the actual application scenario of the fiber optic gyroscope is 0. ~9000 Set different typical rates The range accuracy of the single-axis rate turntable is 1.40625°.

[0031] When the fiber optic gyroscope in S3 is powered on, 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 this embodiment of the invention, within 5 seconds of the fiber optic gyroscope being powered on, the single-axis rate turntable is activated, causing it to move at an angular rate... Uniform rotation, rotation time A fixed value is set for easy comparison. In this embodiment, the rotation time... Set to 30 seconds. The angular rate is set to 9000 according to application requirements. 7200 5400 3600 1000 720 and 360 .

[0033] The single-axis rate turntable described in S4 operates at an angular rate, and a data acquisition device is used to collect the pulse signals output by the single-axis rate turntable and the fiber optic gyroscope in real time.

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

[0035]

[0036] In the formula, The scaling factor is the ratio of the input angular velocity. and temperature The relevant functions, This is the inherent zero bias of the gyroscope. The scale factor error caused by the zero bias can be expressed as:

[0037]

[0038] Typically, the inherent zero bias of a medium-to-high precision fiber optic gyroscope is less than... From the above formula, it can be seen that when the gyroscope rotates at a relatively high angular velocity at a constant speed, the output error of the gyroscope represents the change in the scaling factor caused by temperature. Simultaneously, when the gyroscope operates at the same temperature and rotates at a relatively high angular velocity, the output error of the gyroscope represents the error in the scaling factor caused by the rotational speed. Assuming that the scaling factor temperature error has been compensated, the compensated scaling factor error is only related to the input angular velocity, expressed as... , Room temperature.

[0039] The output signals of the single-axis rate turntable and the fiber optic gyroscope are rectangular pulse signals. A total of 128 pulses are output for one revolution. Each pulse contains a high level and a low level. The angle represented by the width of the high and low levels is 360 / 128 / 2=1.40625°. That is, the level is flipped every time the rotation is 1.40625°.

[0040] After the S5 rotation time reaches the fixed value, the single-axis rate turntable stops and the fiber optic gyroscope is de-energized.

[0041] S6 calculates the angle drift error of the fiber optic gyroscope at angular rate and rotation time based on the pulse signals output by the single-axis rate turntable and the fiber optic gyroscope.

[0042] In this embodiment of the invention, the angular rate of the fiber optic gyroscope is calculated based on the output data of the single-axis rate turntable and the fiber optic gyroscope. and rotation time The corresponding angle drift error The pulse output of the single-axis rate turntable is achieved by fixing a 128-tooth gear with the same tooth pitch on a plane parallel to the turntable surface inside the turntable. A grating is then applied to the gear. As the turntable rotates, the grating outputs a high level when it hits the tooth tip and a low level when it hits the tooth root. This allows the turntable to maintain an angular accuracy of 1.40625° regardless of the rotation angle. The gyroscope's pulse output signal is generated by converting the digital output of the gyroscope into a pulse level signal in software. Specifically, the digital output of the gyroscope is accumulated. When the accumulated value is greater than or equal to the accumulated value P corresponding to 1.40625°, the gyroscope pulse level signal is flipped, and the accumulated value is subtracted from P and updated. This process is repeated. The gyroscope's output angle drift error... It can be represented as

[0043]

[0044] in, This refers to the time corresponding to the rising edge of the current pulse of the turntable output signal. The time width of the current pulse of the turntable output signal. The gyroscope output signal corresponds to the time of the rising edge of an adjacent pulse. This refers to the time width of adjacent pulses in the gyroscope's output signal.

[0045] Based on the angle drift error, S7 divides the entire angular rate range into several angular rate intervals and calculates the scaling factor compensation value corresponding to each angular rate interval. The value is then corrected in the software, and the angle drift error operation is repeated. If the compensated angle drift error is still too large, the scaling factor compensation value is adjusted slightly until the compensated error is within the permissible range.

[0046] In this embodiment of the invention, after a period of time, the gyroscope temperature is allowed to return to room temperature, and steps S3, S4, S5, and S6 are repeated to obtain the gyroscope at the input angular rate. The corresponding angle drift errors are as follows: Based on the angle drift error, the entire angular rate range is divided into m angular rate intervals. ;

[0047] In this embodiment, the angle drift error before compensation is shown in Table 1, and therefore divided into 3 angular rate intervals. , , .

[0048] Calculate the scale factor compensation value for each angular rate interval, correct it in the software, and then obtain the angle drift error to get the compensated angle drift error. .

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

[0050]

[0051] in, The rotation time of the turntable. The scaling factor is measured according to the method in GJB 2426A-2004.

[0052] Then divide the angular velocity range Inside indivual Corresponding output digital quantity Substitute into the formula The least squares method can be used to obtain the angular velocity interval for each region. Corresponding scale factor If the compensated angle drift error is still too large, the scale factor compensation value can be adjusted slightly until the compensated error is within the permissible range.

[0053] Table 1 Comparison of Angle Drift Error Before and After Scale Factor Nonlinearity Compensation

[0054]

[0055] The above-disclosed method is merely a preferred embodiment of the method for reducing the scaling factor nonlinearity of a large dynamic fiber optic gyroscope according to the present invention. Of course, it should not be construed as limiting the scope of the present invention. Those skilled in the art can understand that all or part of the process of implementing the above embodiments and equivalent changes made in accordance with the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for reducing the scaling factor nonlinearity of a large dynamic range fiber optic gyroscope, characterized in that, Includes the following steps: The fiber optic gyroscope is fixed on a single-axis rate turntable, with the test axis perpendicular to the turntable surface. Based on the range required for the actual application scenario of the fiber optic gyroscope, different typical rates are set on the single-axis rate turntable control console. When the fiber optic gyroscope is powered on, 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 rate turntable operates at an angular rate, and the pulse signals output by the single-axis rate turntable and the fiber optic gyroscope are collected in real time using a data acquisition instrument. Once the rotation time reaches the fixed value, the single-axis rate turntable stops, and the fiber optic gyroscope is de-energized. Based on the pulse signals output by the single-axis rate turntable and the fiber optic gyroscope, the angle drift error of the fiber optic gyroscope at the angular rate and rotation time is calculated. Based on the angle drift error, the entire angular rate range is divided into several angular rate intervals, and the scaling factor compensation value corresponding to each angular rate interval is calculated and corrected in the software. The angle drift error calculation process is repeated. If the compensated angle drift error is still too large, the scaling factor compensation value is adjusted slightly until the compensated error is within the permissible range. The formula for calculating the angle drift error is: ； This refers to the time corresponding to the rising edge of the current pulse of the turntable output signal. The time width of the current pulse of the turntable output signal. This refers to the time corresponding to the rising edge of the pulse adjacent to the gyroscope output signal. This refers to the time width of adjacent pulses in the gyroscope's output signal.

2. The method for reducing the scaling factor nonlinearity of a large dynamic range fiber optic gyroscope as described in claim 1, characterized in that: The required measurement range for the practical application of the fiber optic gyroscope is 0. ~9000 .

3. The method for reducing the scaling factor nonlinearity of large dynamic fiber optic gyroscopes as described in claim 1, characterized in that: The range accuracy of the single-axis rate turntable is 1.40625°.

4. The method for reducing the scaling factor nonlinearity of a large dynamic range fiber optic gyroscope as described in claim 1, characterized in that: The angular rate is set to 9000 according to application requirements. 7200 5400 3600 1000 720 and 360 .

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