Current-driven fiber-optic gyroscope circuit board crosstalk detection device and method

Abstract

The application discloses a kind of based on current drive's fiber-optic gyroscope circuit board crosstalk detection device and method, belong to fiber-optic gyroscope technical field.The device includes light source drive board, wide spectrum light source, coupler, Y waveguide, 1 / 4 wave plate, fiber ring, detector, winding coil and equivalent rotation speed drive module.Equivalent rotation speed drive module applies varying current to the coil wound on fiber ring, and uses Faraday effect to generate varying phase difference in fiber ring, so as to equivalent Sagnac phase difference caused by rotating platform, realize quantitative detection to the measured circuit board crosstalk.The application can complete circuit board level crosstalk test alone without using rotating platform, avoid electromagnetic interference and environmental disturbance introduced by rotating platform, and the size and period of excitation current are controllable, can simulate different precision rotation speed input, with the advantages of low cost, convenient operation, accurate measurement.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic gyroscope technology, and particularly relates to a crosstalk detection device and method for a current-driven fiber optic gyroscope circuit board. Background Technology

[0002] The detection scheme for fiber optic gyroscopes primarily employs a fully digital closed-loop approach. This type of fiber optic gyroscope features a large dynamic range and good scaling factor linearity. The fully digital closed-loop fiber optic gyroscope converts the light intensity signal after sensing the rotational speed information into a voltage signal. This signal is then amplified and converted from analog to digital, finally becoming a digital signal. Demodulation, processing, and feedback are then performed in a digital signal processor. For the working principle of the fiber optic gyroscope closed-loop system, please refer to [link to relevant documentation]. Figure 1 As shown, A / D is an analog-to-digital converter; Δ s The Sagnac phase difference caused by rotational speed; Δ m The phase difference generated by the modulated signal; Δ f The phase difference generated by the closed-loop feedback of the fiber optic gyroscope, ideally, is related to the Δ being tracked. s Equivalent sign reversed; Δ e The closed-loop error is approximately zero during closed-loop operation; Z represents the Z-transform of the signal; the magnitude of crosstalk can be approximated as proportional to the amplitude of the generated step wave, where... ，K This is the crosstalk equivalent coefficient.

[0003] With the continuous maturation of optical devices, the five major optical components used in fiber optic gyroscopes (light source, coupler, Y-waveguide, fiber optic loop, and detector) have become standardized. The detection circuit board has become a crucial component affecting the performance indicators of fiber optic gyroscopes, directly influencing gyroscope performance, with crosstalk being the most direct factor. In fiber optic gyroscope circuit boards, the feedback signal acts directly on the Y-waveguide for driving, typically with an amplitude of several volts; the rotational speed signal output by a fully digital closed-loop gyroscope is only tens of microvolts, and the two signals are at the same frequency. The feedback signal can affect the small signal at the front end through paths such as power supply, common ground, and spatial radiation on the circuit board. Moreover, with miniaturization, the impact of crosstalk becomes more significant, manifesting as nonlinearity in the fiber optic gyroscope output and severely affecting the detection signal-to-noise ratio.

[0004] At low speeds, the closer the speed is to 0, the longer the step wave reset time, and the more pronounced the crosstalk in the output, ultimately manifesting as a "dead zone" where the output is zero. Figure 2 As shown, the test "dead zone" must be given a sufficiently small rotational speed input, i.e., a very small phase difference.

[0005] Typically, after assembling the fiber optic gyroscope, a test fixture is used to place the gyroscope's sensitive axis horizontally. A single-axis rate turntable is then used to rotate the gyroscope, changing its orientation so that the sensitive axis gradually passes due east, with the speed input gradually decreasing until it crosses 0° / h. The magnitude of circuit board crosstalk is then quantitatively analyzed. However, this testing method has certain limitations. Circuit board crosstalk cannot be detected at the board level alone; it requires verification after the entire device is assembled. The magnitude of circuit board crosstalk cannot be analyzed independently. The testing process requires a turntable, which typically uses servo circuitry driven by pulse width modulation (PWM), resulting in significant electromagnetic interference. The test dead zone is usually tested at low speeds using a turntable. At low speeds, turntable speed control is difficult, and factors such as frictional nonlinearity, jitter amplification, and insufficient resolution at low speeds lead to high costs for turntables with high accuracy at low speeds. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned problems by proposing a current-driven fiber optic gyroscope circuit board crosstalk detection device and method. This invention solves the technical problems in the prior art where circuit board crosstalk cannot be detected independently at the board level and can only be tested after the entire machine is assembled, resulting in long R&D iteration cycles and high rework costs; and where the detection equipment generates strong electromagnetic interference, resulting in low detection accuracy and the inability to perform fine analysis.

[0007] This invention discloses a crosstalk detection device for a fiber optic gyroscope circuit board based on current drive, comprising a light source drive board, a broadband light source, a coupler, a Y waveguide, a quarter-wave plate, a fiber optic loop, a detector, a wound coil, and an equivalent rotation speed drive module.

[0008] The light source driver board is connected to the broadband light source;

[0009] The broadband light source is connected to the first port of the coupler;

[0010] One side of the Y-waveguide is set to single-ended, and the other side is set to double-ended;

[0011] The second port of the coupler is connected to one end of the Y-waveguide;

[0012] The two ends of the Y-waveguide are connected to one end of each of the two quarter-wave plates;

[0013] The other ends of the two quarter-wave plates are connected to the two pigtails of the fiber optic ring, respectively.

[0014] The detector is connected to the third port of the coupler;

[0015] The winding coil is wound around the fiber optic ring;

[0016] The circuit board under test is connected to the Y-waveguide and the detector, respectively.

[0017] The equivalent speed drive module is electrically connected to the winding coil and is used to apply a changing current to the winding coil. The Faraday effect is used to generate a changing phase difference in the fiber optic loop, and the crosstalk of the circuit board under test is evaluated through the phase difference.

[0018] Optionally, the equivalent speed drive module includes a host computer, control software, and a programmable current source.

[0019] Optionally, the first port and the third port of the coupler are located on the same side of the coupler, and the third port and the second port are located on opposite sides of the coupler.

[0020] Another aspect of the present invention discloses a method for detecting crosstalk on a fiber optic gyroscope circuit board, which uses the aforementioned current-driven fiber optic gyroscope circuit board crosstalk detection device for detection, and includes the following steps:

[0021] Step S1: Connect the circuit board under test to the detector and the Y waveguide; set the starting current and current change rate through the equivalent rotation speed drive module, and output the changing current to the winding coil;

[0022] Step S2: Based on the varying current applied to the winding coil, a varying phase difference is generated in the fiber optic loop using the Faraday effect, and the magnitude of crosstalk on the circuit board under test is evaluated through the phase difference;

[0023] The expression for the changing phase difference is:

[0024] Δ I =VNI

[0025] Where V is the Wilder constant, N is the number of turns of the wound coil, and I is the magnitude of the varying current applied to the wound coil.

[0026] Optionally, in step S2, the specific steps for evaluating the crosstalk magnitude of the circuit board under test through phase difference are as follows:

[0027] A changing phase difference Δ is generated by applying a varying current to the wound coil. I Obtain the dead zone of the fiber optic gyroscope circuit board crosstalk detection device The expression is:

[0028]

[0029] Where L and D are the length and diameter of the fiber optic ring, respectively; Indicates wavelength; Represents the speed of light;

[0030] Dead zone of fiber optic gyroscope circuit board crosstalk detection device The value is the crosstalk size of the circuit board under test.

[0031] Optionally, the changing current in step S1 is a fixed amount of current output by the equivalent speed drive module at fixed intervals to generate a stepped current.

[0032] Optionally, before step S1, a self-calibration step is included for the crosstalk detection device on the fiber optic gyroscope circuit board, the specific steps of which are as follows:

[0033] After calibrating the fiber optic gyroscope circuit board crosstalk detection device, the phase difference corresponding to the latitudinal component of the Earth's rotation speed corresponding to the sensitive axis of the fiber optic ring in the device is obtained. Current is applied to the winding coil so that the rotation speed output of the circuit board under test is 0±0.01° / h, thus obtaining an accurate reference current. The accurate phase difference corresponding to the latitudinal component of the Earth's rotation speed and the reference current are used to perform self-calibration of the fiber optic gyroscope circuit board crosstalk detection device.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] (1) The fiber optic gyroscope circuit board crosstalk detection device of the present invention uses the Faraday effect to generate a phase difference as an external excitation to test the circuit board crosstalk. It no longer uses the turntable for traditional testing. This method is more convenient and is not limited by the usage environment. At the same time, it avoids the additional electromagnetic interference and external environmental disturbances introduced by the turntable, which helps to measure the crosstalk of the gyroscope circuit board more accurately.

[0036] (2) The crosstalk detection device of the fiber optic gyroscope circuit board of the present invention is used to control the magnitude of the driving current of the equivalent rotational speed signal phase difference, thereby changing the magnitude and period, and thus simulating the input of different rotational speed phase differences to achieve dead zone testing with different precision.

[0037] (3) Compared with the turntable, the fiber optic gyroscope circuit board crosstalk detection device of the present invention can generate a smaller and more stable excitation, while greatly reducing the cost. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly introduced below. The features and advantages of the present invention can be more clearly understood by referring to the accompanying drawings. The accompanying drawings are schematic and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of a digital closed-loop detection model for fiber optic gyroscopes in the existing technology;

[0040] Figure 2 A diagram of stepped wave crosstalk signal in the output data of a fiber optic gyroscope.

[0041] Figure 3 This is a schematic diagram of the crosstalk detection device for fiber optic gyroscope circuit boards of the present invention.

[0042] Figure 4 This is a flowchart illustrating the operation of the fiber optic gyroscope circuit board crosstalk detection device of the present invention.

[0043] Figure 5 This is a schematic diagram of the output current of the fiber optic gyroscope circuit board crosstalk detection device of the present invention;

[0044] Figure 6 This is a schematic diagram showing the correspondence between the applied current and the output signal of the fiber optic gyroscope circuit board crosstalk detection device of the present invention.

[0045] Explanation of reference numerals in the attached figures:

[0046] 1-Light source driver board, 2-Broadband light source, 3-Coupled, 4-Y waveguide, 5-1 / 4 wave plate, 6-Fiber optic ring, 7-Detector, 8-Wound coil, 9-Equivalent speed drive module. Detailed Implementation

[0047] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0048] A specific embodiment of the present invention, such as Figure 3 As shown, a crosstalk detection device for a fiber optic gyroscope circuit board based on current drive is disclosed, including a light source drive board 1, a broadband light source 2, a coupler 3, a Y waveguide 4, a quarter-wave plate 5, an optical fiber ring 6, a detector 7, a wound coil 8, and an equivalent speed drive module 9.

[0049] The light source driver board 1 is connected to the pin of the broadband light source 2; the port of the broadband light source 2 is connected to the first port of the coupler 3; one side of the Y-waveguide 4 is single-ended, and the other side is double-ended; the second port of the coupler 3 is connected to the single end of the Y-waveguide 4; the double ends of the Y-waveguide 4 are respectively connected to one end of two quarter-wave plates 5; the other ends of the two quarter-wave plates 5 are connected to the two pigtails of the fiber optic ring 6; the detector 7 is connected to the third port of the coupler 3; the first port and the third port of the coupler 3 are on the same side of the coupler 3, and the third port and the second port are on opposite sides of the coupler 3; the circuit board under test is connected to the Y-waveguide 4 and the detector 7 respectively.

[0050] Furthermore, the Y-waveguide 4 is equipped with two wires, which are soldered to the corresponding two electrode pads on the circuit board under test, respectively.

[0051] The optical signal is emitted through broadband light source 2, and reaches detector 7 via coupler 3, Y waveguide 4, two quarter wave plates 5, and fiber optic loop 6. The circuit board being detected collects the optical signal, processes it, and performs closed-loop control to output rotation speed information.

[0052] Furthermore, the winding coil 8 is wound around the fiber optic ring 6; the winding coil 8 is also connected to the equivalent speed drive module 9, which is used to control the output current that changes at a fixed period to simulate different small speeds for dead zone measurement.

[0053] After the broadband light source is driven by the light source driver board, the light passes through the coupler to the waveguide. The waveguide then polarizes and modulates the light, which is then passed through quarter-wave plates at both ends to convert the linearly polarized light into left-handed and right-handed circularly polarized light, respectively, before entering the fiber ring 6. A magnetic field is generated by the current excitation within the winding coil 8 on the fiber ring 6. The current applied to the winding coil causes a phase difference Δ between the two beams of light in the fiber ring 6. I =VNI, where V is the material's characteristic constant, called the Wilder constant, N is the number of turns of the winding coil 8, and I is the magnitude of the current applied to the winding coil. The two beams of light pass through the quarter-wave plate 5 and enter the fiber ring 6, propagating in opposite directions in the fiber ring. After entering their respective other quarter-wave plates 5, they are restored to linearly polarized light. The two linearly polarized beams after passing through the quarter-wave plate 5 interfere with each other, and the signal carries the non-reciprocal phase difference generated by the Faraday effect.

[0054] Furthermore, the equivalent speed drive module 9 includes a host computer, control software, and a programmable current source. By operating the control software on the host computer, the high-precision programmable current source is controlled to output a varying current. The equivalent speed drive module applies current to the wound coil 8, and by changing the current, alters the phase difference generated by the Faraday effect, thus simulating the Sagnac phase difference change caused by the turntable rotation. This allows for the simulation of different small rotational speeds, replacing the turntable angular velocity input to perform dead-zone testing of the fiber optic gyroscope, and is used to evaluate the magnitude of crosstalk on the fiber optic gyroscope circuit board.

[0055] Preferably, the programmable current source is a high-precision programmable current source.

[0056] Another aspect of the invention, see also Figure 4 The paper also discloses a method for detecting crosstalk on a fiber optic gyroscope circuit board, which uses the aforementioned crosstalk detection device for the fiber optic gyroscope circuit board and includes the following steps:

[0057] Step S1: Connect the circuit board under test to the detector 7 and Y-waveguide 4 in the fiber optic gyroscope circuit board crosstalk detection device; set the starting current and current change rate, etc., through the control software of the host computer in the equivalent speed drive module 9; control the programmable current source to output a changing current and apply it to the winding coil 8, such as... Figure 5 As shown. At regular intervals, the programmable current source outputs a current with a fixed change, where T is the time taken for the current to change by the fixed amount, ΔI is the set current change, and I0 is the reference current.

[0058] Step S2: Applying a varying current to the wound coil 8 generates a varying phase difference Δ I =VNI, the Sagnac phase difference generated by the equivalent rotation of the turntable through this phase difference, is used to evaluate the crosstalk magnitude of the circuit board under test.

[0059] To facilitate understanding of the above technical solutions of the present invention, the following detailed description of the above technical solutions of the present invention is provided through specific embodiments.

[0060] Taking a circuit board for a high-precision fiber optic gyroscope with a length L = 4200m and a diameter D = 120mm as an example, a dead zone test is performed using a turntable rotating at a speed of 0.01° / s. The Sagnac phase difference caused by the rotation speed Ω is... for:

[0061]

[0062] in, Indicates wavelength; It represents the speed of light.

[0063] The Sagnac phase difference generated per second of rotational speed is approximately 8*10. -8 rad, in order to achieve the same measurement accuracy as the turntable (i.e., the change in current alters the phase difference generated by the Faraday effect, to be equivalent to the Sagnac phase difference caused by the rotation of the turntable), according to Δ I =VNI = Δ s The V Wilder constant is chosen to be 1*10. -5 Special optical fibers with a rad / A capacity are used to reduce the cost of high-precision programmable current sources, allowing the high-precision programmable current sources to operate within the 1mA-5A range. The crosstalk detection device for the fiber optic gyroscope circuit board uses a minimum change of 1mA. When N is 4 turns, a change of current of 2mA can achieve the same effect.

[0064] In one embodiment, a turntable is conventionally used to test the dead zone of the fiber optic gyroscope. The turntable rotates at a rate of 0.01° / s, and the test results are as follows. Figure 2As shown, the high-precision fiber optic gyroscope's rotational speed output reaches 0 for 200 seconds, calculated according to the Earth's rotational speed component formula:

[0065]

[0066] Among them, Ω e For the Earth's rotation speed, The latitude of the region This refers to the angle between the axis of rotation (which the fiber optic gyroscope cannot sense) and the due east direction. Based on test results, the dead zone size is approximately 0.25° / h.

[0067] Furthermore, a changing phase difference Δ is generated by applying a varying current to the wound coil 8. I Obtain the dead zone of the fiber optic gyroscope circuit board crosstalk detection device The expression is:

[0068] ;

[0069] Where L and D are the length and diameter of fiber ring 6, respectively; ΔI Deadband When the output of the fiber optic gyroscope is 0, the current difference applied to the winding coil by the equivalent speed drive module is 0.

[0070] Furthermore, the dead zone of the fiber optic gyroscope circuit board crosstalk detection device The value is the crosstalk size of the circuit board under test.

[0071] For example, such as Figure 6 As shown, a fiber optic loop of the same length was used as fiber optic loop 6 in this test equipment. ΔI was set to 2mA and T was set to 1s. After testing, ΔI... Deadband The difference is 600mA, which indicates the dead zone of the fiber optic gyroscope circuit board crosstalk detection device. The dead zone, measured by the fiber optic gyroscope circuit board crosstalk detection device, is approximately the same as the dead zone obtained from the turntable test, with a dead zone rate of 0.28° / h. If the dead zone test result of the designed circuit board exceeds the design threshold, the circuit board needs to be redesigned, and the test repeated until it is less than or equal to the design threshold.

[0072] In one embodiment, after a long period of operation, the power supply and storage devices of the fiber optic gyroscope circuit board crosstalk detection device of the present invention drift. To ensure the accuracy of the applied current used to measure the rotational speed of the equivalent turntable, the device is self-calibrated using the latitudinal component of the Earth's rotational speed. The self-calibration process is as follows:

[0073] After calibration, the detection device obtains the Earth's rotational speed Ω corresponding to the sensitive axis of fiber optic loop 6 in the fiber optic gyroscope circuit board crosstalk detection device. eThe corresponding phase difference Δ E Each time the device is powered on, the current applied to the winding coil 8 is used to bring the rotational speed output of the circuit board under test (i.e., the rotational speed output of the high-precision fiber optic gyroscope) close to 0, thus obtaining an accurate reference current. Taking a certain location as an example, the corresponding Earth rotation speed is 9.6° / h. When calibrating the detection device, the current is adjusted so that the rotational speed output of the circuit board under test is 0, and the reference current I0 is recorded. Before each operation, the device performs self-calibration, repeating the above process, and the measured rotational speed output is 0, and the reference current I0 is recorded. Therefore, the dead zone size correspondence of the fiber optic gyroscope circuit board crosstalk detection device is as follows:

[0074] .

[0075] The technical solution of this invention can realize the separate detection of crosstalk on the circuit board. By using the phase difference generated by the Faraday effect caused by the change of current, it is equivalent to the change of Sagnac phase difference caused by the rotation of the turntable. The magnitude and period can be freely changed to simulate the input of different rotation speed phase differences for quantitative measurement of crosstalk magnitude. Moreover, it does not need to be measured by the traditional turntable method, and it is less affected by external interference factors (electromagnetic interference from the turntable itself), and the cost is lower.

[0076] All of the above-mentioned optional technical solutions can be combined in any way to form optional embodiments of the present invention, and will not be described in detail here.

[0077] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A crosstalk detection device for a current-driven fiber optic gyroscope circuit board, characterized in that, It includes a light source driver board (1), a broadband light source (2), a coupler (3), a Y waveguide (4), a quarter wave plate (5), an optical fiber ring (6), a detector (7), a wound coil (8), and an equivalent rotation speed drive module (9). The light source driver board (1) is connected to the broadband light source (2); The broadband light source (2) is connected to the first port of the coupler (3); One side of the Y waveguide (4) is set as single-ended, and the other side is set as double-ended; The second port of the coupler (3) is connected to one end of the Y waveguide (4); The two ends of the Y waveguide (4) are respectively connected to one end of two quarter wave plates (5); The other ends of the two quarter-wave plates (5) are respectively connected to the two pigtails of the fiber ring (6); The detector (7) is connected to the third port of the coupler (3); The winding coil (8) is wound around the optical fiber ring (6); The circuit board under test is connected to the Y-waveguide (4) and the detector (7) respectively; The equivalent speed drive module (9) is electrically connected to the winding coil (8) and is used to apply a changing current to the winding coil (8). The Faraday effect is used to generate a changing phase difference in the fiber optic loop (6), and the crosstalk magnitude of the circuit board under test is evaluated by the phase difference.

2. The fiber optic gyroscope circuit board crosstalk detection device according to claim 1, characterized in that, The equivalent speed drive module (9) includes a host computer, control software and a programmable current source.

3. The fiber optic gyroscope circuit board crosstalk detection device according to claim 1, characterized in that, The first port and the third port of the coupler (3) are located on the same side of the coupler (3), and the third port and the second port are located on opposite sides of the coupler (3).

4. A method for detecting crosstalk on a fiber optic gyroscope circuit board, characterized in that, The detection using the current-driven fiber optic gyroscope circuit board crosstalk detection device according to any one of claims 1-3 includes the following steps: Step S1: Connect the circuit board under test to the detector (7) and the Y waveguide (4); set the starting current and current change rate through the equivalent rotation speed drive module (9), and output the changing current to the winding coil (8); Step S2: Based on the changing current applied to the winding coil (8), the Faraday effect is used to generate a changing phase difference in the fiber loop (6), and the crosstalk magnitude of the circuit board under test is evaluated by the phase difference; The expression for the changing phase difference is: Δ I =VNI Where V is the Wilder constant, N is the number of turns of the winding coil (8), and I is the magnitude of the changing current applied to the winding coil (8).

5. The method for detecting crosstalk on a fiber optic gyroscope circuit board according to claim 4, characterized in that, In step S2, the specific steps for evaluating the crosstalk magnitude of the circuit board under test through the phase difference are as follows: A changing phase difference Δ is generated by applying a changing current to the wound coil (8). I Obtain the dead zone of the fiber optic gyroscope circuit board crosstalk detection device The expression is: Where L and D are the length and diameter of the fiber optic ring (6), respectively; Indicates wavelength; Represents the speed of light; Dead zone of fiber optic gyroscope circuit board crosstalk detection device The value is the crosstalk size of the circuit board under test.

6. The method for detecting crosstalk on a fiber optic gyroscope circuit board according to claim 4, characterized in that, The changing current in step S1 is a fixed amount of current output by the equivalent speed drive module (9) at fixed intervals to generate a stepped current.

7. The method for detecting crosstalk on a fiber optic gyroscope circuit board according to claim 4, characterized in that, Before step S1, a self-calibration step is included for the crosstalk detection device on the fiber optic gyroscope circuit board. The specific steps are as follows: After calibrating the crosstalk detection device for the fiber optic gyroscope circuit board, the phase difference corresponding to the component of the Earth's rotation speed in latitude corresponding to the sensitive axis of the fiber optic ring (6) in the crosstalk detection device for the fiber optic gyroscope circuit board is obtained. Apply current to the winding coil (8) so that the rotational speed output of the circuit board under test is 0±0.01° / h, and obtain an accurate reference current; use the phase difference corresponding to the latitude component of the Earth's rotational speed and the reference current to perform self-calibration of the fiber optic gyroscope circuit board crosstalk detection device.

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