Photoelectric separation type pure analog output micro fiber optic gyroscope and signal processing method thereof

Abstract

The application discloses a photoelectric separation type micro fiber gyroscope with pure analog output, which comprises an optical system and a circuit system; the circuit system adopts serial D / A output; the circuit system comprises a power supply processing circuit, a host circuit and a filter circuit which are connected with the optical system; the host circuit is used for signal collection, demodulation and modulation, and forming an analog angular rate; the filter circuit is used for second-order filtering of the angular rate analog signal and external output; the circuit system adopts serial D / A output, and a single-chip microcomputer or a DSP processing chip is not used any more, which is beneficial to miniaturization of the circuit and miniaturization of a dual-axis fiber gyroscope; after the circuit system adopts serial D / A output, the circuit cannot be compensated, and an FPGA signal modulation circuit is designed in the host circuit, so that the circuit compensation can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fiber-optic gyroscope, in particular to a photoelectric separation type pure analog output micro fiber-optic gyroscope and a signal processing method thereof. BACKGROUND

[0002] When the traditional dual-axis mechanical gyroscope is matched with a radar antenna system to complete angular rate measurement, motor stall faults frequently occur with the use of a large number of equipment. Although measures such as optimizing assembly process are taken to reduce the failure rate, the effect is not obvious, and it is difficult to solve. With the continuous development of fiber-optic gyroscope, an effective path is provided to solve the reliability and service life problem of mechanical gyroscope used in radar antenna system. Compared with mechanical rotor gyroscope, fiber-optic gyroscope can be called a solid-state gyroscope, which has no mechanical moving parts including gyroscope motor, so there is no motion wear phenomenon, which can fundamentally eliminate the main adverse factors affecting the reliability due to motor stall faults.

[0003] However, the mechanical gyroscope is a dual-axis gyroscope in principle, and there are problems such as miniaturization, signal transmission, and signal processing in replacing the dual-axis mechanical gyroscope with a dual-axis fiber-optic gyroscope. The miniaturization problem is mainly due to the fact that the optical fiber cable has a certain length and cannot be well coiled, and the structure is not compact. The existing signal transmission uses single-chip microcomputers or DSP processing chips, which also occupies a large volume, thereby being not conducive to miniaturization. In the signal processing process, if the sensitive angular velocity is large, the data is easy to overflow, resulting in the problem of opposite signs. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide a photoelectric separation type pure analog output micro fiber-optic gyroscope.

[0005] The purpose of the present application is achieved by the following technical solution: a photoelectric separation type pure analog output micro fiber-optic gyroscope, comprising an optical system and a circuit system; the circuit system adopts serial D / A output;

[0006] The circuit system comprises:

[0007] A power supply processing circuit is connected with the optical system, the host circuit and the filter circuit;

[0008] A host circuit is used for signal acquisition, demodulation and modulation, and forming an analog angular rate;

[0009] Filter circuit, for the angular rate analog signal is filtered and output; Circuit system uses serial D / A output, no longer uses single-chip microcomputer or DSP and other processing chips, is favorable to the miniaturization of the circuit form, is favorable to the miniaturization of double-axis fiber-optic gyroscope, after the circuit system adopts serial D / A output, will lead to the problem that the circuit cannot be compensated, and the FPGA signal mediation circuit is designed in the host circuit, and the circuit compensation can be realized.

[0010] The host circuit includes:

[0011] A / D conversion circuit, for converting analog signal into digital signal;

[0012] FPGA signal mediation circuit, for the digital signal of A / D conversion circuit is truncated, when sensitive to large angular rate, FPGA signal mediation circuit is truncated to data, so that the sign bit does not change, and the data does not flip;

[0013] D / A conversion circuit, for converting the digital signal processed by the FPGA signal mediation circuit into analog signal, and feeding back to the optical system;

[0014] FPGA signal mediation circuit, for the digital signal of A / D conversion circuit is truncated, when sensitive to large angular rate (such as 100 degrees per second angular velocity or more), FPGA signal mediation circuit is truncated to data, so that the sign bit does not change, and the data does not flip; The specific method of truncation is: after the FPGA receives the A / D sampling digital quantity, the phase change corresponding digital demodulation value is obtained by solving, the 56-bit integral value is obtained after the digital demodulation value is integrated, 32-bit digital quantity is taken from the 56-bit integral value as the pre-output quantity of the gyro angular rate, and the high 18-bit data is taken from the 32-bit pre-output quantity value and sent as D / A as the final digital-analog conversion data source. When 32-bit is taken from 56-bit, the data sign bit of the maximum speed range of the gyro should be included, and a truncation margin is reserved, so that the data sign bit of 32-bit and 18-bit can be guaranteed to be opposite to 56-bit, in this case, the truncation should be raised to 43-bit to the 12th bit, to ensure that the data sign bit is consistent with the actual phase direction.

[0015] The filter circuit includes:

[0016] D / A conversion circuit, for converting the digital signal processed by the FPGA signal mediation circuit into analog signal;

[0017] Filtering and amplifying circuit, for filtering and amplifying the analog signal output by the D / A conversion circuit and outputting;

[0018] Reference source generation circuit, for generating stable output voltage for the filtering and amplifying circuit;

[0019] The filtering and amplification circuit adopts an active second-order low-pass filter circuit;

[0020] The optical path system includes a light source, a main beam splitter, two beam splitters, two detectors, two waveguide integrated optical chips, two optical fibers, and a light source driving circuit. The light source driving circuit is connected to a power supply processing circuit. The light source is connected to the two beam splitters through the main beam splitter. The two detectors are respectively connected to the two beam splitters. The two beam splitters are respectively connected to the two waveguide integrated optical chips. The two waveguide integrated optical chips are respectively connected to two optical fiber rings.

[0021] The optical path system is located inside the gyroscope; the circuit system is located on a circuit board outside the gyroscope; the gyroscope and the circuit board are connected by a cable.

[0022] A wave-damping sleeve is provided on the cable connecting the gyroscope and the circuit board.

[0023] A further technical solution is that this invention provides a signal processing method for a micro fiber optic gyroscope with photoelectric separation and pure analog output.

[0024] The present invention has the following advantages:

[0025] 1. The circuit system adopts serial D / A output, eliminating the need for microcontrollers or DSPs, which facilitates the miniaturization of the circuit and the dual-axis fiber optic gyroscope. However, the use of serial D / A output can lead to circuit compensation issues. By designing an FPGA signal modulation circuit in the host circuit, circuit compensation can be achieved.

[0026] 2. Preferably, in the host circuit, an FPGA signal conditioning circuit is used to truncate the digital signal of the A / D conversion circuit. When a large angular rate is detected, the FPGA signal conditioning circuit truncates the data so that the sign bit does not change and the data does not flip. Attached Figure Description

[0027] Figure 1 This is a block diagram illustrating the principle of a photoelectric-separated, purely analog output micro fiber optic gyroscope.

[0028] Figure 2 This is a schematic diagram of data processing in an FPGA signal modulation circuit.

[0029] Figure 3 This is a flowchart of the data processing for an FPGA signal modulation circuit.

[0030] Figure 4 This is an overall layout diagram of a photoelectric-separated pure analog output micro fiber optic gyroscope from one perspective.

[0031] Figure 5The overall layout of the photoelectric separation type pure analog output micro optical fiber gyroscope from another perspective.

[0032] Figure 6 The structure schematic of the frame of the photoelectric separation type pure analog output micro optical fiber gyroscope from one perspective.

[0033] Figure 7 The structure schematic of the frame of the photoelectric separation type pure analog output micro optical fiber gyroscope from another perspective.

[0034] Figure 8 The structure schematic of the reference source generation circuit.

[0035] Figure 9 The structure schematic of the active second-order low-pass filter circuit.

[0036] Figure 10 The simulation result of the output circuit.

[0037] In the figure: 1. frame; 2. light source; 3. main beam splitter; 4. first beam splitter; 5. second beam splitter; 6. first Y waveguide; 7. second Y waveguide; 8. first fiber ring; 9. second fiber ring; 10. first detector; 11. second detector; 12. first mounting groove; 13. second mounting groove. DETAILED DESCRIPTION

[0038] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application.

[0040] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0041] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0042] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0043] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] Example 1: As Figures 1 to 10 As shown, a miniature fiber optic gyroscope with optoelectronic separation and pure analog output includes an optical path system and a circuit system; the circuit system adopts serial D / A output;

[0045] The circuit system includes:

[0046] The power supply processing circuit is connected to the optical system, the host circuit, and the filter circuit.

[0047] The main circuit is used for signal acquisition, demodulation and modulation, and to generate analog angular rates.

[0048] The filtering circuit is used to perform second-order filtering on the angular rate analog signal and output it externally.

[0049] The circuit system adopts serial D / A output, eliminating the need for microcontrollers or DSPs, which facilitates the miniaturization of the circuit and the dual-axis fiber optic gyroscope. However, the use of serial D / A output can lead to circuit compensation issues. By designing an FPGA signal modulation circuit in the host circuit, circuit compensation can be achieved.

[0050] The host circuit includes:

[0051] An A / D conversion circuit is used to convert analog signals into digital signals.

[0052] The FPGA signal conditioning circuit is used to truncate the digital signal from the A / D conversion circuit. When sensitive to large angular rates (such as angular velocities above 100 degrees per second), the FPGA signal conditioning circuit truncates the data to ensure that the sign bit does not change and the data does not flip. The specific truncation method is as follows: After receiving the sampled digital quantity from the A / D converter, the FPGA calculates the digital demodulated value corresponding to the phase change. This demodulated value is then passed through an integrator to obtain a 56-bit integral value. 32 bits are truncated from this 56 bits as the pre-output quantity of the gyroscope's angular rate. The high 18 bits are then truncated from this 32-bit pre-output value and sent to the D / A converter as the final digital-to-analog conversion data source. When truncating 32 bits from 56 bits, the sign bit of the data within the gyroscope's maximum speed measurement range must be included, and a truncation margin must be reserved. This ensures that the sign bits of the 32-bit and 18-bit data are opposite to those of the 56-bit data. In this case, the truncation should be increased to bits 43 to 12 to ensure that the sign bit of the data is consistent with the direction of the actual phase.

[0053] The D / A conversion circuit is used to convert the digital signal processed by the FPGA signal modulation circuit into an analog signal and feed it back to the optical system.

[0054] The filter circuit includes:

[0055] The D / A conversion circuit is used to convert the digital signal processed by the FPGA signal modulation circuit into an analog signal.

[0056] The filtering and amplification circuit is used to filter and amplify the analog signal output from the D / A conversion circuit.

[0057] The reference source generation circuit is used to generate a stable output voltage for the filter and amplifier circuit. In this embodiment, the reference source generation circuit uses the CW6350 precision voltage reference source from Beijing Yuxiang to generate a stable 5.0V output voltage for the output stage circuit. Changes in power supply voltage, ambient temperature, or load conditions have minimal impact on the output voltage.

[0058] The filtering and amplification circuit adopts an active second-order low-pass filter circuit; such as Figure 9 As shown, the amplification factor is adjustable, with a design parameter of 2x, achieving an output voltage range of ±10 V. The designed bandwidth is approximately 140Hz, which can be adjusted by modifying the parameters of the second-order RC network. The second-order low-pass network composed of R309*, C320*, and R310, C316* effectively reduces output stage noise. The amplification factor can be easily and effectively adjusted by modifying the ratio of R309* to R311*. The design of R312 improves the load-carrying capacity of the output stage.

[0059] The optical path system comprises a light source 2, a main beam splitter 3, two beam splitters, two detectors, two waveguide integrated optical chips, two fiber rings and a light source 2 driving circuit; the light source 2 driving circuit is connected with a power supply processing circuit; the light source 2 is connected with the two beam splitters through the main beam splitter 3; the two detectors are connected with the two beam splitters respectively; the two beam splitters are connected with the two waveguide integrated optical chips respectively; the two waveguide integrated optical chips are connected with the two fiber rings respectively;

[0060] The optical path system is arranged in the gyroscope, and the circuit system is arranged on the circuit board outside the gyroscope; the gyroscope is connected with the circuit board through a cable; in the embodiment, the length of the cable connecting the circuit board and the fiber-optic gyroscope is 1.4 m; the optical path system is arranged in the gyroscope, and the circuit system is arranged on the circuit board outside the gyroscope, so that the photoelectric separation of the product is realized, and the miniaturization of the two-axis fiber-optic gyroscope is realized. Figures 4-7 As shown in the figure, all the optical devices and fiber rings are mounted on the frame 1, the frame 1 can be directly mounted on the system, and a lot of switching links are reduced. All the optical devices and fiber rings are mounted on the frame 1, so that the gyroscope is a monolithic structure, rather than a separate structure like building blocks, which is conducive to improving the anti-vibration performance; the two fiber rings are arranged on the frame 1 structure, and the two fiber rings are arranged on the upper part and the lower part of the frame 1 structure respectively, because the installation space on the frame 1 is limited after the miniaturization of the product, and the fiber ring occupies a relatively large space, the two fiber rings are arranged respectively to facilitate the full use of space.

[0061] Figure 6 And Figure 7 For the gyroscope frame 1 stripped of the optical devices and fiber rings, the first mounting groove 12 is arranged on the upper part of the frame 1 corresponding to the first fiber ring 8; the second mounting groove 13 is arranged on the lower part of the frame 1 corresponding to the second fiber ring 9; the light source 2, the main beam splitter 3, the first beam splitter 4 and the first Y waveguide 6 are mounted on the upper part of the frame 1, so as to arrange the optical fibers between the optical devices; the second mounting groove 13 is arranged on the lower part of the frame 1 corresponding to the second fiber ring 9; the second mounting groove 13 is arranged on the lower part of the frame 1 corresponding to the second fiber ring 9; the second beam splitter 5 and the second Y waveguide 7 are mounted on the lower part of the frame 1, so as to arrange the optical fibers between the optical devices; the first detector 10 and the second detector 11 are welded on a circuit board, and the optical signal is converted into an electrical signal.

[0062] The cable connecting the gyroscope and the circuit board is provided with a wave-proof sleeve; the wave-proof sleeve is conducive to preventing electromagnetic interference.

[0063] In the embodiment, the operational amplifier has good bit error and non-linear characteristics, and can realize filter amplification of the output stage.

[0064] Circuit amplification multiple:

[0065] Cutoff frequency:

[0066] The circuit design parameters are simulated, and the simulation results are shown in Figure 10

[0067] Embodiment 2: As shown in Figure 2 and 3 A signal processing method of a micro optical fiber gyroscope with photoelectric separation and pure analog output, comprising the following steps:

[0068] Step 1): The interference optical signal of the Sagnac closed loop is passed through digital demodulation to obtain a digital signal corresponding to the phase change;

[0069] Step 2): The digital signal of the phase change is integrated and accumulated to form a 56-bit angular rate digital signal original value;

[0070] Step 3): The original value of the angular rate digital signal is selected to form a 32-bit angular rate pre-transmission signal;

[0071] Step 4): The output amplitude of the angular rate pre-transmission signal is compared to determine whether the pre-transmission signal contains the maximum measurement range;

[0072] Step 5): The angular rate pre-transmission signal is selected to form an 18-bit digital signal which is sent to a serial digital-to-analog converter for external output.

[0073] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or replace some of the technical features with equivalent ones, as long as they are within the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made within the scope of the present application shall be included in the protection scope of the present application.​

Claims

1. A miniature fiber optic gyroscope with photoelectric separation and purely analog output, comprising an optical path system and a circuit system; characterized in that: The circuit system adopts serial D / A output; The circuit system comprises: A power supply processing circuit connected with the optical system, the host circuit and the filter circuit; A host circuit for signal collection, demodulation and modulation, and forming an angular rate of analog quantity; A filter circuit for second-order filtering of the angular rate analog signal and external output; The host circuit comprises: An A / D conversion circuit for converting analog signals into digital signals; An FPGA signal modulation circuit for clipping the digital signals of the A / D conversion circuit, so that the sign bit does not change and the data does not flip when a large angular rate is sensed; A D / A conversion circuit for converting the digital signals processed by the FPGA signal modulation circuit into analog signals and feeding back to the optical system; After the FPGA receives the A / D sampled digital quantity, the phase change corresponding digital demodulation value is obtained by calculation, and the 56-bit integral value is obtained after the integrator. The 32-bit digital quantity is clipped from the 56-bit integral value as the pre-output quantity of the gyro angular rate, and the high 18-bit data is clipped from the 32-bit pre-output quantity value and sent as D / A as the final digital-analog conversion data source; The filter circuit comprises: A D / A conversion circuit for converting the digital signals processed by the FPGA signal modulation circuit into analog signals; A filter amplification circuit for filtering and amplifying the analog signals output by the D / A conversion circuit and outputting; A reference source generation circuit for generating a stable output voltage for the filter amplification circuit; The optical system comprises a light source, a main beam splitter, two beam splitters, two detectors, two waveguide integrated optical chips, two fiber rings and a light source driving circuit; the light source driving circuit is connected with the power supply processing circuit; the light source is connected with the two beam splitters through the main beam splitter; the two detectors are respectively connected with the two beam splitters; the two beam splitters are respectively connected with the two waveguide integrated optical chips; the two waveguide integrated optical chips are respectively connected with the two fiber rings; The signal processing method of the fiber optic gyroscope comprises the following steps: Step 1): obtaining the phase change corresponding digital quantity signal by digital demodulation of the interference light signal of the Sagnac closed loop; Step 2): integrating and accumulating the digital quantity signal of the phase change to form a 56-bit angular rate digital signal original value; Step 3): clipping the original value of the angular rate digital signal to form a 32-bit angular rate pre-transmission signal; Step 4): comparing the output amplitude of the angular rate pre-transmission signal to determine whether the pre-transmission signal contains the maximum measurement range; Step 5): clipping the angular rate pre-transmission signal to form an 18-bit digital quantity transmitted to a serial digital-analog converter for external output.

2. The opto-electrically separated pure analog output micro-fiber-optic gyroscope according to claim 1, characterized in that: The filter amplification circuit adopts an active second-order low-pass filter circuit.

3. The opto-electrically separated pure analog output micro-fiber-optic gyroscope according to claim 1, characterized in that: The optical system is arranged inside the gyroscope; the circuit system is arranged on the circuit board outside the gyroscope; the gyroscope and the circuit board are connected through a cable.

4. The opto-electrically separated pure analog output micro-fiber-optic gyroscope according to claim 3, characterized in that: A wave-proof sleeve is arranged on the cable connecting the gyroscope and the circuit board.

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