Method for testing transit time of fiber-optic gyroscope

Abstract

The invention discloses a method for testing the transit time of a fiber-optic gyroscope, and solves the problems that a traditional testing method reserves a testing point on a fiber-optic gyroscope circuit, and an oscilloscope is used for measuring the testing point, so that the consumed time is long, and a certain measurement error exists; the repeated plugging and unplugging of the oscilloscope meter pen may cause damage to components on the circuit, which is not beneficial to the batch production of the fiber-optic gyroscope; the method comprises the following steps: modulating an optical signal input into a fiber-optic gyroscope into an electric signal through a photoelectric detector, demodulating the electric signal through a demodulation circuit to obtain a modulated square wave, and carrying out digital sampling on the demodulation circuit generating the modulated square wave through an A / D converter in the demodulation circuit to obtain a sampling value; the transition time of the fiber-optic gyroscope is debugged according to the modulation period of the modulation square wave; according to the method, an oscilloscope is not needed for measurement, manual measurement errors are reduced, and the measurement accuracy is improved; meanwhile, the non-contact operation of debugging personnel and the fiber-optic gyroscope circuit board can be realized, and the damage of human factors to the circuit is avoided.

Description

Technical Field

[0001] The invention relates to a method for testing parameters of a fiber optic gyroscope, and in particular to a method for testing the transit time of a fiber optic gyroscope. Background Art

[0002] Fiber optic gyroscopes have the advantages of impact resistance, high sensitivity, long life, large dynamic range, and short startup time, and have been widely used in inertial navigation systems. In the debugging process of the fiber optic gyroscope production process, the fiber optic gyroscope needs to be debugged in order to measure the accurate transit time parameters.

[0003] The traditional test method reserves test points on the fiber optic gyroscope circuit and uses an oscilloscope to measure the test points. This method is time-consuming and has certain measurement errors. At the same time, the repeated insertion and removal of the oscilloscope probe may also damage the components on the circuit, which is not conducive to the mass production of gyroscopes. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the traditional test method reserves test points on the fiber optic gyroscope circuit and uses an oscilloscope to measure the test points, which is time-consuming and has certain measurement errors; at the same time, repeated insertion and removal of the oscilloscope probe may also cause damage to components on the circuit, which is not conducive to the mass production of the fiber optic gyroscope; and to provide a test method for the transit time of the fiber optic gyroscope.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A method for testing the transit time of an optical fiber gyroscope is characterized in that it comprises the following steps:

[0007] S1, modulate the received optical signal into an electrical signal through a photodetector, demodulate the electrical signal with a demodulation circuit to obtain a modulated square wave, and digitally sample the demodulation circuit that generates the modulated square wave through an A / D converter in the demodulation circuit to obtain a sampling value;

[0008] S2, set the sampling value threshold P'0 of the A / D converter, and estimate the transit time of the fiber optic gyroscope according to the length of the fiber optic ring in the fiber optic gyroscope τ0 , given an initial modulation period T of the modulated square wave, the modulated square wave is loaded onto the Y waveguide according to the initial modulation period T;

[0009] S3, determine the maximum value of the sampling value output by the A / D converter within the time period of |T-τ0|; and calculate the number of overflow sampling values;

[0010] S4, debug modulation cycle T i , so that after modulation, the time length is |T i-τ0|, the number of overflow sampling values ​​output by the A / D converter is 0 and the maximum sampling value is not greater than the sampling value threshold P′0. The modulation period T i as the final FOG transit time.

[0011] The fiber optic gyroscope transit time testing method of the present invention does not need to use an oscilloscope for measurement, reduces human measurement errors, and improves measurement accuracy; at the same time, it can realize non-contact operation between debugging personnel and the fiber optic gyroscope circuit board, avoiding damage to the circuit by human factors.

[0012] Further, in S4, the debugging modulation period is specifically the current modulation period plus 1 or minus 1.

[0013] Furthermore, S4 is specifically:

[0014] S41, taking the modulation period T′=T-1, determining the maximum value of the sampling value output by the A / D converter within the time period of |T′-τ0|; and calculating the number of overflowed sampling values ​​at the same time;

[0015] S42, determine whether the number of overflowed sampling values ​​within the time period |T′-τ0| is 0, if not 0, execute S45, otherwise, execute S43;

[0016] S43, judging whether the maximum value of the sampling value in the time period of |T′-τ0| is less than the sampling value threshold value P′0, if it is less than, then outputting the modulation period T′ as the final fiber optic gyroscope transit time, completing the debugging of the fiber optic gyroscope transit time; if it is not less than, executing S44;

[0017] S44, determine whether the maximum value of the sampling value in the time period of |T′-τ0| is less than the maximum value of the sampling value in the time period of |T-τ0|, if less, return to S41; otherwise, execute S46;

[0018] S45, determine whether the number of overflowed sampling values ​​within the time period of |T′-τ0| is less than the number of sampling values ​​within the time period of |T-τ0|, if so, return to S41, otherwise execute S46;

[0019] S46, debugging the modulation period T″=T′+1, determining the maximum value of the sampling value output by the A / D converter within the time period of |T″-τ0|; and calculating the number of overflowed sampling values ​​at the same time;

[0020] S47, determine whether the number of overflowed sampling values ​​within the time period of |T″-τ0| is 0, if not 0, execute S410, otherwise, execute S48;

[0021] S48, determine whether the maximum value of the sampling value within the time period of |T″-τ0| is less than the sampling value threshold P0 ′ , if it is less than, then the output modulation period T″ is the final FOG transit time, and the FOG transit time debugging is completed; if it is not less than, execute S49;

[0022] S49, determine whether the maximum value of the sampling value in the time period of |T″-τ0| is less than the maximum value of the sampling value in the time period of |T′-τ0|, if less, take T′=T″, return to S46; otherwise, take T=T″, return to S41;

[0023] S410, determine whether the number of overflow sampling values ​​within the time period of |T″-τ0| is less than the number of overflow sampling values ​​within the time period of |T′-τ0|; if so, take T′=T″ and return to S46; otherwise, take T=T″ and return to S41.

[0024] Furthermore, S4 is automatically executed through the debugger.

[0025] Further, the fiber optic gyroscope includes a connected photodetector, a demodulation circuit, a Y waveguide and a fiber optic ring;

[0026] The optical signal is input into the Y-waveguide through the optical path for modulation and then enters the optical fiber ring for interference. The optical signal after interference is input into the photodetector through the Y-waveguide, converted into an electrical signal, and demodulated by the demodulation circuit to obtain a modulated square wave.

[0027] Furthermore, the demodulation circuit includes a filter circuit, an A / D converter, an amplifier circuit, a drive circuit, a D / A converter, and an FPGA chip.

[0028] Beneficial effects of the present invention:

[0029] 1. A method for testing the transit time of a fiber optic gyroscope of the present invention does not require the use of an oscilloscope for measurement, thereby reducing human measurement errors and improving measurement accuracy; at the same time, it can achieve contactless operation between debugging personnel and the fiber optic gyroscope circuit board, thus avoiding damage to the circuit caused by human factors.

[0030] 2. The present invention provides a method for testing the transit time of a fiber optic gyroscope, which is automatically executed through a debugging program to automatically complete accurate debugging of the transit time of the fiber optic gyroscope. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a principle block diagram of a fiber optic gyroscope in an embodiment of a method for testing the transit time of a fiber optic gyroscope of the present invention;

[0032] Figure 2It is a waveform diagram of the relationship between the modulation signal and the interference light intensity when the modulation signal of the modulated square wave> the fiber optic gyroscope transit time τ in an embodiment of a method for testing the transit time of the fiber optic gyroscope of the present invention;

[0033] Figure 3 It is a waveform diagram of the relationship between the modulation signal and the interference light intensity when the modulation signal of the modulated square wave is less than the fiber optic gyroscope transit time τ in an embodiment of the test method of the fiber optic gyroscope transit time of the present invention;

[0034] Figure 4 This is a flow chart of S4 in an embodiment of a method for testing the transit time of a fiber optic gyroscope of the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In this embodiment, the fiber optic gyroscope includes a connected photodetector, a demodulation circuit, a Y waveguide and a fiber optic ring;

[0037] The optical signal is input into the Y-waveguide through the optical path for modulation and then enters the optical fiber ring for interference. The optical signal after interference is input into the photodetector through the Y-waveguide, converted into an electrical signal, and demodulated by the demodulation circuit to obtain a modulated square wave.

[0038] Schematic diagram Figure 1 As shown:

[0039] The optical path converts the sensed angular rate error signal into an electrical signal through a photodetector. After the electrical signal collected by the A / D converter in the demodulation circuit is resolved and processed, the error signal and the modulated square wave are applied to the Y waveguide. The Y waveguide controls the optical fiber ring to change the phase difference of the light, thereby achieving modulation.

[0040] The fiber optic gyroscope superimposes the modulated square wave (T: modulation period) on the Y waveguide in a cycle with τ (τ: transit time). The transit time τ0 of the fiber optic gyroscope is estimated based on the length of the fiber ring in the fiber optic gyroscope, as follows: Figure 2 and Figure 3As shown in the figure, when T>τ or T<τ, the interference light intensity signal |T-τ0| is stronger than the adjacent position, and the sampling value collected by the A / D converter is greater than the adjacent position within |T-τ|. Due to factors such as the non-ideality of components, |T-τ| cannot be equal to zero; the closer the modulated square wave period T is to the actual transit time τ, the smaller the sampling value collected by the A / D converter within |T-τ|. When |T-τ| is greater than a certain value, the sampling value of the A / D converter will overflow, and the sampling value is the positive maximum value of the A / D.

[0041] The present embodiment provides a method for testing the transit time of a fiber optic gyroscope, comprising the following steps:

[0042] S1. Modulate the optical signal input to the fiber optic gyroscope into an electrical signal through a photoelectric detector, demodulate the electrical signal with a demodulation circuit to obtain a modulated square wave, and digitally sample the demodulation circuit that generates the modulated square wave through an A / D converter in the demodulation circuit to obtain a sampling value; wherein the demodulation circuit includes a filter circuit, an A / D converter, an amplification circuit, a drive circuit, a D / A converter, and an FPGA chip.

[0043] S2, setting the sampling value threshold P′0 of the A / D converter, estimating the transit time τ0 of the fiber optic gyroscope according to the length of the fiber optic ring in the fiber optic gyroscope, giving the initial modulation period T of the modulated square wave, and loading the modulated square wave onto the Y waveguide according to the initial modulation period T;

[0044] S3, determine the maximum value of the sampling value output by the A / D converter within the time period of |T-τ0|; and calculate the number of overflow sampling values;

[0045] S4, debug modulation cycle T i , so that after modulation, the time length is |T i -τ0|, the number of overflow sampling values ​​output by the A / D converter is 0 and the maximum sampling value is not greater than the sampling value threshold value P′0. The modulation period Ti is used as the final fiber optic gyroscope transit time and can be automatically executed by the debugging program; specifically, Figure 4 As shown:

[0046] S41, taking the modulation period T′=T-1, determining the maximum value of the sampling value output by the A / D converter within the time period of |T′-τ0|; and calculating the number of overflowed sampling values ​​at the same time;

[0047] S42, determine whether the number of overflowed sampling values ​​within the time period |T′-τ0| is 0, if not 0, execute S45, otherwise, execute S43;

[0048] S43, judging whether the maximum value of the sampling value in the time period of |T′-τ0| is less than the sampling value threshold value P′0, if it is less than, then outputting the modulation period T′ as the final fiber optic gyroscope transit time, completing the debugging of the fiber optic gyroscope transit time; if it is not less than, executing S44;

[0049] S44, determine whether the maximum value of the sampling value in the time period of |T′-τ0| is less than the maximum value of the sampling value in the time period of |T-τ0|, if less, return to S41; otherwise, execute S46;

[0050] S45, determine whether the number of overflowed sampling values ​​within the time period of |T′-τ0| is less than the number of sampling values ​​within the time period of |T-τ0|, if so, return to S41, otherwise execute S46;

[0051] S46, debugging the modulation period T″=T′+1, determining the maximum value of the sampling value output by the A / D converter within the time period of |T″-τ0|; and calculating the number of overflowed sampling values ​​at the same time;

[0052] S47, determine whether the number of overflowed sampling values ​​within the time period of |T″-τ0| is 0, if not 0, execute S410, otherwise, execute S48;

[0053] S48, judging whether the maximum value of the sampling value in the time period of |T″-τ0| is less than the sampling value threshold value P0′, if it is less than, then outputting the modulation period T″ as the final FOG transit time, completing the debugging of the FOG transit time; if it is not less than, executing S49;

[0054] S49, determine whether the maximum value of the sampling value in the time period of |T″-τ0| is less than the maximum value of the sampling value in the time period of |T′-τ0|, if less, take T′=T″, return to S46; otherwise, take T=T″, return to S41;

[0055] S410, determine whether the number of overflow sampling values ​​within the time period of |T″-τ0| is less than the number of overflow sampling values ​​within the time period of |T′-τ0|; if so, take T′=T″ and return to S46; otherwise, take T=T″ and return to S41.

[0056] Example 1

[0057] The actual transit time of a certain type of fiber optic gyroscope is 7000ns, and the method of this embodiment is used for verification:

[0058] The modulation period T plus 1 or minus 1 represents an increase or decrease of 10ns. The initial external input modulation period T is 600 (indicating that the modulation period T=6000ns), the program first subtracts 1 from the modulation period, that is, T is 599. In the first sampling time period, the number of overflows of the sampling values ​​of the A / D converter is greater than the number of overflows of the sampling values ​​of the A / D converter when T=600, indicating that the modulation period should not be reduced but should be increased; in the next sampling time period, the program adds 1 to the modulation period, that is, the modulation period T is 600, the number of overflows of the sampling values ​​of the A / D converter is less than the number of overflows of the sampling values ​​of the A / D converter when T=599, and the modulation period increases correctly; in the next sampling time period, the modulation period continues to add 1, that is, the modulation period T is 601, the number of overflows of the sampling values ​​of the A / D converter is less than the number of overflows of the sampling values ​​of the A / D converter when T=600, ..., the modulation period continues to add 1, and when the modulation period T is 700, the maximum value of the sampling value that triggers the A / D converter is less than the sampling value threshold P0′ of the A / D converter, so the modulation period T=700 at this time is locked as the transit time τ. At this time, the output waveform of the photodetector is monitored by an oscilloscope, and the width between the peak and the trough of the waveform at the modulation period point is the narrowest.

[0059] Example 2

[0060] When the initial external input modulation period T is 800 (indicating the modulation period T=8000ns), the program first subtracts 1 from the modulation period, i.e., T is 799. In the first sampling time period, the number of sampling value overflows of the A / D converter is less than the number of sampling overflows of the A / D converter when T=800, indicating that the modulation period should be reduced. In the next sampling time period, the modulation period is subtracted by 1 through the test program, i.e., the modulation period T is 798, and the number of sampling overflows of the A / D converter is less than the number of sampling overflows of the A / D converter when T=799. In the next sampling time period, the modulation period continues to be subtracted by 1, i.e., the modulation period T is 797, and the number of sampling overflows of the A / D converter is less than the number of sampling overflows of the A / D converter when T=798, ... The modulation period continues to be subtracted by 1. When the modulation period T is 700, the maximum sampling value that triggers the A / D converter is less than the sampling value threshold P′0 of the A / D converter. Therefore, the modulation period T=700 at this time is locked as the transit time τ.

[0061] The above description is only a specific embodiment of the present invention, and a comparison of the effects of the specific embodiments and the related comparative examples, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for testing the transit time of a fiber optic gyroscope, characterized in that: The following steps are involved: S1, modulate the received optical signal into an electrical signal through a photodetector, demodulate the electrical signal with a demodulation circuit to obtain a modulated square wave, and digitally sample the demodulation circuit that generates the modulated square wave through an A / D converter in the demodulation circuit to obtain a sampling value; S2. Set the sampling value threshold of the A / D converter P0 ′ , the transit time of the FOG is estimated based on the length of the fiber loop in the FOG τ0 , given an initial modulation period T of the modulated square wave, the modulated square wave is loaded onto the Y waveguide according to the initial modulation period T; S3, determine the maximum value of the sampling value output by the A / D converter within the time period of |T-τ0|; and calculate the number of overflow sampling values; S4, debugging modulation cycle Ti , so that after modulation, the time length is | Ti - During the τ0| period, the number of sampling value overflows output by the A / D converter is 0 and the maximum sampling value is not greater than the sampling value threshold. P0 ′ , the modulation period Ti as the final FOG transit time.

2. A method for testing the transit time of an optical fiber gyroscope according to claim 1, characterized in that: In S4, the debugging modulation period is specifically the current modulation period plus 1 or minus 1.

3. A method for testing the transit time of an optical fiber gyroscope according to claim 2, characterized in that: S4 is specifically: S41, get modulation cycle T′ ＝ T - 1 , determine the maximum value of the sampling value output by the A / D converter within the time period of |T′-τ0|; and calculate the number of overflow sampling values ​​at the same time; S42, determine whether the number of overflowed sampling values ​​within the time period |T′-τ0| is 0, if not 0, execute S45, otherwise, execute S43; S43, determine whether the maximum value of the sampling value within the time period of |T′-τ0| is less than the sampling value threshold P0 ′ , if it is less than, then the output modulation period T ′ is the final FOG transit time, completing the debugging of the FOG transit time; if it is not less than, executing S44; S44, judging whether the maximum value of the sampling value in the time period of |T′-τ0| is less than the maximum value of the sampling value in the time period of |T-τ0|, if it is less, returning to S41; Otherwise, execute S46; S45, determine whether the number of overflowed sampling values ​​in the time period of |T′-τ0| is less than the number of sampling values ​​in the time period of T-τ0|, if so, return to S41, otherwise execute S46; S46, debugging modulation cycle T″ ＝ T′ + 1 , determine the maximum value of the sampling value output by the A / D converter within the time period of |T″-τ0|; and calculate the number of overflow sampling values ​​at the same time; S47, determine whether the number of overflowed sampling values ​​within the time period of |T″-τ0| is 0, if not 0, execute S410, otherwise, execute S48; S48, determine whether the maximum value of the sampling value within the time period of |T″-τ0| is less than the sampling value threshold P0 ′ , if it is less than, then the output modulation period T ″ is the final fiber optic gyroscope transit time, completing the debugging of the fiber optic gyroscope transit time; if it is not less than, executing S49; S49, determine whether the maximum value of the sampling value in the time period of |T″-τ0| is less than the maximum value of the sampling value in the time period of T′-τ0|, if less than, take T′ ＝ T″ , return to S46; otherwise, take T ＝ T″ , return to S41; S410, determine whether the number of overflowed sampling values ​​in the time period of |T″-τ0| is less than the number of overflowed sampling values ​​in the time period of T′-τ0|, if less, take T′ ＝ T″ , then return to S46, otherwise, take T ＝ T″ , return to S41.

4. The method for testing the transit time of an optical fiber gyroscope according to claim 1, characterized in that: S4 is automatically executed through the debugger.

5. The method for testing the transit time of an optical fiber gyroscope according to claim 1, characterized in that: The fiber optic gyroscope includes a connected photodetector, a demodulation circuit, a Y waveguide and a fiber optic ring; The optical signal is input into the Y-waveguide through the optical path for modulation and then enters the optical fiber ring for interference. The optical signal after interference is input into the photodetector through the Y-waveguide, converted into an electrical signal, and demodulated by the demodulation circuit to obtain a modulated square wave.

6. A method for testing the transit time of an optical fiber gyroscope according to claim 1 or 5, characterized in that: The demodulation circuit includes a filter circuit, an A / D converter, an amplifier circuit, a drive circuit, a D / A converter, and an FPGA chip.

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