CN114858155A - A digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system and method - Google Patents

Abstract

The invention discloses a digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system and method. An optical signal is sent to a photoelectric detector through an optical fiber ring and a photoelectric modulator; The amplifier circuit is sent to the A/D conversion module; the A/D conversion module generates a digital signal and sends it to the closed-loop algorithm central processing unit; the closed-loop algorithm central processing unit performs closed-loop calculation to obtain a digital modulation signal; the proportional coefficient adjustment module generates the adjustment electrical signal, D The /A conversion module receives and processes the digital modulation signal under the action of adjusting the electric signal, generates a feedback electric signal, and generates the Y-waveguide modulation signal through the driving circuit; the photoelectric modulator modulates the phase of the fiber ring according to the Y-waveguide modulation signal to generate a phase difference . The invention adopts the compensation method of introducing resistance to adjust the digital closed-loop proportional coefficient, which simply and reliably solves the problem of matching between the half-wave voltage of the Y-waveguide of the fiber optic gyro and the software parameters, and reduces the management cost.

Description

A digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system and method

technical field

The invention belongs to the field of inertial technology, and relates to a system and a method for adjusting the closed-loop proportional coefficient of a digital closed-loop fiber optic gyro by using a resistance.

Background technique

Most of the current fiber optic gyroscopes use digital closed-loop solutions. During the debugging process of the fiber-optic gyroscope, the proportional coefficient of the digital closed-loop needs to be adjusted, because the half-wave voltage of each Y-waveguide is different, and the general floating range is 2.5V~ 3.5V, in order to correspond to the fluctuation of the half-wave voltage of the Y-waveguide, the closed-loop proportional coefficient needs to be adjusted accordingly. For digital closed-loop, the easiest way is to directly adjust the digital proportional coefficient for each set of fiber optic gyroscopes.

However, for aerospace products, the digital closed-loop control processor of the fiber optic gyroscope for space generally uses the anti-fuse chip of ACTEL Company. If the chip needs to change the digital scale factor, there are two methods: one is to change the FPGA software, After changing the parameters of each product, the program needs to be recompiled, so the FPGA program of each product is different. According to the software management specification of aerospace products, it is necessary to re-run some third-party evaluation processes for each product FPGA software. It takes a lot of manpower, material resources and time; secondly, a ROM chip needs to be matched outside the FPGA, and the proportional parameter needs to be solidified into the anti-fuse ROM after product debugging. bring about an increase in cost.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the above-mentioned defects, and provide a digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system and method. The optical fiber ring acquires the optical signal from the photoelectric modulator, and sends the optical signal to the photodetector through the photoelectric modulator; the photodetector receives the optical signal from the optical fiber ring, performs photoelectric conversion processing on the optical signal, and generates an electrical signal. Send the electrical signal to the preamplifier circuit; the preamplifier circuit receives the electrical signal from the photodetector, performs DC blocking and filtering processing on the electrical signal in turn, generates a PIN electrical signal, and sends the PIN electrical signal to the A/D conversion module ; The A/D conversion module receives the PIN electrical signal from the preamplifier circuit, performs analog-to-digital conversion processing on the PIN electrical signal, generates a digital signal, and sends the digital signal to the closed-loop algorithm central processing unit; the closed-loop algorithm central processing unit receives A/D The digital signal from the D conversion module is closed-loop calculated to obtain a digital modulation signal, and the digital modulation signal is sent to the D/A conversion module; the proportional coefficient adjustment module generates the adjustment electrical signal in the D/A conversion module; D The /A conversion module receives the digital modulation signal from the closed-loop algorithm central processing unit, performs digital-to-analog conversion processing on the digital modulation signal under the action of the adjustment electric signal, generates a feedback electric signal, and sends the feedback electric signal to the driving circuit; the driving circuit Receive the feedback electrical signal from the D/A conversion module and amplify it, generate a Y-waveguide modulation signal, and send the Y-waveguide modulation signal to the photoelectric modulator; the photoelectric modulator receives the Y-waveguide modulation signal from the drive circuit, and according to Y The waveguide modulation signal performs phase modulation on the optical signal of the optical fiber ring, so that the optical signal produces a phase difference. The invention adopts the compensation method of adjusting the digital closed-loop proportional coefficient by introducing resistance, which simply and reliably solves the problem of matching between the half-wave voltage of the Y-waveguide of the fiber optic gyro and the software parameters, reduces the management cost, and is especially suitable for the dispersion of the half-wave voltage of the Y-waveguide of the aerospace products. Application scenarios of closed-loop proportional coefficient adjustment.

To achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

A digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system, comprising a photodetector, a preamplifier circuit, an A/D conversion module, a closed-loop algorithm central processing unit, a D/A conversion module, a drive circuit, a photoelectric modulator, an optical fiber loop and a proportional coefficient adjustment module;

Photoelectric modulator: receives the optical signal sent by the light source, polarizes and modulates the optical signal and sends it to the optical fiber loop;

Optical fiber ring: acquire the optical signal from the photoelectric modulator, and send the optical signal to the photoelectric detector through the photoelectric modulator;

Photodetector: Receive the optical signal from the optical fiber ring; perform photoelectric conversion processing on the optical signal, generate an electrical signal, and send the electrical signal to the preamplifier circuit;

Preamplifier circuit: receives the electrical signal from the photodetector; performs DC blocking and filtering processing on the electrical signal in turn; generates PIN electrical signal; sends the PIN electrical signal to the A/D conversion module;

A/D conversion module: receive the PIN electrical signal from the preamplifier circuit; perform analog-to-digital conversion processing on the PIN electrical signal to generate a digital signal; send the digital signal to the closed-loop algorithm central processing unit;

Closed-loop algorithm central processing unit: receives the digital signal from the A/D conversion module; performs closed-loop calculation on the digital signal to obtain a digital modulation signal, and sends the digital modulation signal to the D/A conversion module;

Proportional coefficient adjustment module: generate the adjustment electrical signal in the D/A conversion module;

D/A conversion module: receives the digital modulation signal from the closed-loop algorithm central processing unit, performs digital-to-analog conversion processing on the digital modulation signal under the action of adjusting the electric signal, and generates a feedback electric signal; sends the feedback electric signal to the driving circuit;

Drive circuit: receive the feedback electrical signal from the D/A conversion module and amplify it to generate a Y-waveguide modulation signal; send the Y-waveguide modulation signal to the photoelectric modulator;

Photoelectric modulator: receives the Y-waveguide modulation signal from the drive circuit, and modulates the phase of the optical signal of the fiber ring according to the Y-waveguide modulation signal, so that the optical signal produces a phase difference.

Further, by adjusting the equivalent resistance value of the proportional coefficient adjustment module, an adjustment electrical signal is generated in the D/A conversion module.

Further, the proportional coefficient adjustment module is a series-parallel resistance network formed by several resistors.

Further, one end of the proportional coefficient adjustment module is connected to the voltage reference source in the D/A conversion module, and the other end is connected to the reference ground in the D/A conversion module.

Further, the Y-waveguide modulation signal causes the optical signal of the fiber ring to generate a phase difference of π/2.

Further, the proportional coefficient adjustment module generates an adjustment electrical signal in the D/A conversion module to make K _f K _C 2 ^N =2π, wherein K _f K _C is the digital closed-loop fiber optic gyroscope closed-loop proportional coefficient, and the positive integer N is D. /A The number of bits of the register in the conversion module.

Further, the equivalent resistance value R _SET of the proportional coefficient adjustment module is adjusted according to the PIN electrical signal of the preamplifier circuit, and the specific method is to adjust the equivalent resistance value R _SET of the proportional coefficient adjustment module so that the PIN electrical signal becomes a straight line. .

Further, the equivalent resistance value R _SET of the proportional coefficient adjustment module is determined according to the following relational formula:

Among them, _VB is the fluctuation amplitude in the PIN electrical signal of the preamplifier circuit, and the empirical formula parameters k and b are obtained by _fitting according to multiple groups of _{VB1, VB2..., R SET1 ,} R _SET2 .

A method for adjusting the closed-loop proportional coefficient of a digital closed-loop fiber optic gyroscope, implemented according to the above-mentioned system for adjusting the closed-loop proportional coefficient of a digital closed-loop fiber optic gyroscope, includes the following steps:

The photoelectric modulator receives the optical signal sent by the light source, polarizes and modulates the optical signal, and sends it to the optical fiber loop;

The optical fiber loop obtains the optical signal from the photoelectric modulator, and sends the optical signal to the photodetector through the photoelectric modulator;

The photodetector receives the optical signal from the optical fiber ring; performs photoelectric conversion processing on the optical signal, generates an electrical signal, and sends the electrical signal to the preamplifier circuit;

The preamplifier circuit receives the electrical signal from the photodetector; performs DC blocking and filtering processing on the electrical signal in turn; generates a PIN electrical signal; sends the PIN electrical signal to the A/D conversion module;

The A/D conversion module receives the PIN electrical signal from the preamplifier circuit; performs analog-to-digital conversion processing on the PIN electrical signal to generate a digital signal; sends the digital signal to the closed-loop algorithm central processing unit;

The closed-loop algorithm central processing unit receives the digital signal from the A/D conversion module; performs closed-loop calculation on the digital signal to obtain a digital modulation signal, and sends the digital modulation signal to the D/A conversion module;

The proportional coefficient adjustment module generates the adjustment electrical signal in the D/A conversion module;

The D/A conversion module receives the digital modulation signal from the closed-loop algorithm central processing unit, performs digital-to-analog conversion processing on the digital modulation signal under the action of adjusting the electric signal, and generates a feedback electric signal; sends the feedback electric signal to the driving circuit;

The drive circuit receives the feedback electrical signal from the D/A conversion module and amplifies it to generate a Y-waveguide modulation signal; sends the Y-waveguide modulation signal to the photoelectric modulator;

The photoelectric modulator receives the Y-waveguide modulation signal from the driving circuit, and modulates the phase of the optical signal of the fiber ring according to the Y-waveguide modulation signal, so that the optical signal produces a phase difference.

Further, in the above-mentioned method for adjusting the closed-loop proportional coefficient of a digital closed-loop fiber optic gyroscope, the equivalent resistance value of the proportional coefficient adjusting module is adjusted, and an adjusting electrical signal is generated in the D/A conversion module, and the specific method is:

Adjust the equivalent resistance value R _SET of the proportional coefficient adjustment module to make the PIN electrical signal of the preamplifier circuit become a straight line;

Or, determine the equivalent resistance value R _SET of the proportional coefficient adjustment module according to the following relationship:

Among them, _VB is the fluctuation amplitude in the PIN electrical signal of the preamplifier circuit, and the empirical formula parameters k and b are obtained by _fitting according to multiple groups of _{VB1, VB2..., R SET1 ,} R _SET2 .

Compared with the prior art, the present invention has the following beneficial effects:

(1) The present invention innovatively proposes a method of using resistance to adjust the closed-loop proportional coefficient, which simplifies the adjustment of the closed-loop proportional coefficient into a conventional resistance adjustment, simplifies the product debugging process, lowers the product debugging threshold, and facilitates The batch engineering of fiber optic gyroscope products greatly reduces the production cost of fiber optic gyroscopes for space and avoids the drawbacks caused by software updates;

(2) The present invention can obtain the resistance value after fitting according to a specific circuit, with high flexibility and strong universality.

Description of drawings

1 is a schematic diagram of a digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system of the present invention;

Fig. 2 is the schematic diagram of the square wave modulation principle of the central processing unit of the closed-loop algorithm; wherein (a) is the waveform diagram of the modulation square wave, and (b) is the waveform diagram of the modulation phase;

Fig. 3 is a schematic diagram of the feedback principle of the staircase wave; wherein (a) is the waveform diagram of the staircase wave, and (b) is the waveform diagram of the feedback phase;

FIG. 4 is a simplified structural block diagram of the D/A conversion module B9762AMG of the present invention.

Detailed ways

The features and advantages of the present invention will become clearer and clearer through the detailed description of the present invention below.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. While various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

The invention relates to a method for adjusting the closed-loop proportional coefficient of digital closed-loop fiber optic gyro by using resistance. It consists of a module, a driving circuit, an optoelectronic modulator (Y waveguide) and an optical fiber ring. The electrical signal converted from the detector is collected by the A/D, and then enters the FPGA for demodulation and integration, and the digital quantity corresponding to the phase difference generated by the current angle is calculated. After the multiplier, the digital quantity is sent to the D/A as the feedback step quantity , which is fed back to the Y waveguide through the drive circuit. In order to correspond to the discreteness of the half-wave voltage of the Y-waveguide, the closed-loop proportional coefficient needs to be adjusted accordingly. For aerospace products, the management cost of adjusting the resistance parameters is better than the software parameters. The invention adopts the compensation method of introducing resistance to adjust the digital closed-loop proportional coefficient, and solves the problem of matching between the half-wave voltage of the Y-waveguide of the fiber optic gyro and the software parameters simply and reliably. The invention avoids the drawbacks caused by software update, simplifies the adjustment of the closed-loop proportional coefficient into the conventional resistance adjustment, simplifies the product debugging process, lowers the product debugging threshold, facilitates the batch engineering of fiber optic gyroscope products, and greatly reduces the The production cost of fiber optic gyroscopes for space is reduced.

As shown in Figure 1, this patent is a system for adjusting the closed-loop proportional coefficient of digital closed-loop fiber optic gyroscope by using resistance. , drive circuit, photoelectric modulator (Y waveguide), fiber ring and adjustment resistor. The working process of the optical path is as follows: the light is emitted by the light source, divided into two parts by the coupler, one beam is transmitted to the Y waveguide, and the other beam is transmitted to the empty head. The Y-waveguide polarizes and modulates the input light into two beams, which are transmitted clockwise and counterclockwise, and enter the fiber ring. The transmission of the two beams of light in the optical fiber ring will produce a phase difference proportional to the rotational angular velocity. The two beams of light reconverge into the Y-waveguide to interfere and then convert into a change in light intensity, and then reach the detector through a coupler and become a change in current. After A/D acquisition, it enters the FPGA for closed-loop control, superimposes the rotational speed information on the bias modulation signal, and forms a staircase wave, that is, a digital modulation signal, which is fed back to the Y-waveguide for the next cycle of signal modulation.

An important function of the Y-waveguide is to introduce a phase difference between the forward and reverse beams, which is achieved by a phase modulator. The phase modulator uses the Pockels effect to make two electrodes on the surface of the substrate on both sides of the waveguide. If the distance between the two electrodes is L and the length is D, when a voltage V is applied to the two electrodes, the light generated by the light passing through the waveguide will be affected. The phase shift is:

where n ₁ is the refractive index of the optical waveguide, r is the photoelectric coefficient of the waveguide material, and λ is the wavelength of light passing through the waveguide;

An important indicator of the Y-waveguide is the half-wave voltage. The half-wave voltage is the voltage that needs to be added to the electrode to make the passing light produce a πrad phase shift, which reflects the phase adjustment capability of the modulator.

The required voltage is added to the Y-waveguide electrode, and the forward and reverse beams pass through the same phase modulator at different times, resulting in a phase difference as follows:

ΔΦ _F = Φ(t)-Φ(t-τ)=K _f [V(t)-V(t-τ)], where τ is the group delay of the fiber ring, i.e. the light required to propagate in the fiber ring time, K _f is the modulation factor of the modulator.

Ω(S)是输入角速度，ΔΦ_S(S)为引起的相位差，c为光速，S为自动控制原理中传递函数的算子。The optical fiber ring provides a closed optical path for the transmission of the forward and reverse beams of light, and is sensitive to the input of external angular velocity, which is converted into the phase difference between the two beams of light. The resulting phase difference between the two beams is determined by the Sagnac effect. Considering the propagation delay of light, the dynamic model of the Sagnac effect is expressed as

Ω(S) is the input angular velocity, ΔΦ _S (S) is the induced phase difference, c is the speed of light, and S is the operator of the transfer function in the automatic control principle.

The two beams of forward and reverse light returned from the fiber ring are combined at the splitting point of the Y-waveguide, because the phase difference will cause interference, resulting in the change of the optical power P, which is expressed as P∝P ₀ (1+cos(ΔΦ)), In the formula, P ₀ represents the sum of the optical powers of the two beams of light, and ΔΦ is the phase difference between the two beams of light.

In order to achieve the highest sensitivity of the light intensity reaching the detector, a phase offset is artificially introduced between the two oppositely transmitted beams to shift the working point to other positions, thereby improving the sensitivity of the gyro and reflecting the directionality of rotation. The waveform of the modulated square wave V _F (t) is shown in Figure 2.

The half period is τ and the amplitude is V _π2 , the voltage that can cause a π/2 phase shift. The phase difference ΔΦ _F (t) between the two beams caused by V _F (t) is

As shown in Figure 2(b), after adding square wave modulation, the interference formula becomes

After demodulation, it is ΔP(ΔΦ _S )=P ₀ (1+sinΔΦ _S )-P ₀ (1-sinΔΦ _S )=2P ₀ sinΔΦ _S

The digital closed-loop scheme generates a feedback phase shift by adding a phase staircase wave to the phase modulator. The digital signal processing circuit calculates the feedback amount D _out (n) according to a specific algorithm according to the demodulated error signal. D _out (n) is integrated to form a digital staircase wave D _JT (n), that is, the digital modulation signal is a digital staircase wave, which is converted into an analog staircase wave V _JT (t) by D/A and driving, and added to the phase modulator. The waveform of V _JT (t) is shown in Fig. 3, and the width of each step is τ. The phase difference ΔΦ _JT (t) between the two beams caused by V _JT (t) is

ΔΦ _JT (t)=K _f (V _JT (t)-V _JT (t-τ))

=K _f K _C (D _JT (n)-D _JT (n-1))

=K _f K _C D _out (n)

In the formula, K _C is the proportional coefficient determined by A/D, D/A, front-end circuit, and drive circuit, and ΔΦ _JT (t) is proportional to the feedback amount D _out (n).

The staircase wave cannot be infinitely rising, there must be a reset. The automatic reset of the staircase wave can be realized by using the digital staircase wave feedback. The reset value D _JT (n) of the digital staircase wave is stored in the digital register. The number of bits N of the register is the same as that of the parallel D/A converter. When the accumulated value exceeds 2N or is less than 0, it will automatically overflow and reset. It can be proved that as long as the gain K _f K _C of the modulation channel is adjusted, that is, the digital closed-loop proportional coefficient, so that K _f K _C 2 ^N = 2π, that is, when the D/A converter is full-scale output, the analog voltage after the driving circuit is added to On the phase modulator, the passing light just causes a phase shift of 2πrad (also called 2π voltage), and the reset of the staircase wave will not affect the performance of the gyro, so this reset operation is also called 2π reset. When a reset occurs, the equation will change to the following form:

ΔΦ _JT (t)=K _f K _C (D _JT (n)±2 ^N -D _JT (n-1))

=K _f K _C D _OUT (n)±K _f K _C 2 ^N

=K _f K _C D _OUT (n)±2πD _OUT (n) is a digital signal modulated by a square wave.

The simplified block diagram of the D/A conversion chip B9762AMG is shown in Figure 4, which mainly includes a DAC core, digital control logic, and full-scale output current control. The DAC core contains an array of PMOS current sources capable of delivering up to 20mA of full-scale current (I _OUTFS ), which can be divided into 31 equal current sources to form the most significant 5 bits. The next 4 bits (middle significant bits) contain 15 equal value current sources whose value is 1/16 of the corresponding current source value of the most significant bit (MSB).

All current sources are output to one end or the other end of the differential output through the PMOS differential current switch, that is, the I _OUTA or I _OUTB end. The differential switching structure used reduces switching transient distortion and also reduces synchronization errors.

The B9762AMG is a differential complementary current output, and the complementary current output is provided by the complementary terminals I _OUTA and I _OUTB . When all bits are high (that is, DAC CODE = 4095), I _OUTA provides a near full-scale current output, while the complementary terminal I _OUTB has no current output. The current output at I _OUTA and I _OUTB is a function of the input code and I _OUTFS and can be expressed as:

I _OUTA = (DACCODE/4096)×I _OUTFS

I _OUTB = (4095-DACCODE)/4096×I _OUTFS

Where DACCODE=0 to 4095 (decimal), I _OUTFS is a function of the reference current I _REF , which is _{determined by the reference voltage V REF and} the external resistor R _SET , and can be expressed as:

I _OUTFS = 32×I _REF

Where: I _REF =V _REF /R _SET

The B9762AMG includes a control amplifier that adjusts the full-scale output current I _OUTFS . The control amplifier can be regarded as a VI converter, and its current output I _REF is determined by the ratio of V _REF to the external resistor R _SET . I _REF is replicated to the segmented current source with an appropriate scaling factor to set I _OUTFS .

The control amplifier allows I _OUTFS to have a wide adjustment range. By adjusting I _REF from 62.5uA to 625uA, I _OUTFS can be changed from 2mA to 20mA. I _OUTFS has a wide adjustment range and mainly has two advantages: one is to make the power consumption of the B9762 directly proportional to I _OUTFS ; the other is to control the system gain.

The principle of adjusting the digital closed-loop proportional coefficient K _f K _C in the present invention is: according to the automatic reset mechanism of the digital closed-loop fiber optic gyroscope, when K _f K _C 2 ^N = 2π, the automatic reset of D/A will not affect the performance of the fiber optic gyroscope . The modulation coefficient K _f of the Y waveguide is related to the half-wave voltage of the Y waveguide, so K _C needs to be adjusted for each set of fiber optic gyroscopes, in fact: K _C =K _R ×K _Y

In the formula, K _R is the multiplication coefficient in the closed loop. In the same system, K _R can be regarded as unchanged, and _KY is the proportional coefficient of the hardware circuit (ie, the proportional coefficient adjustment module): _KY =I _OUTFS

In summary, we can get:

That is, when the following equation holds, the system can just eliminate the reset error:

This patent is to adjust the closed-loop proportional coefficient of digital closed-loop fiber optic gyroscope by adjusting R _SET . That is, by adjusting R _SET , adjusting the proportional coefficient KY of the hardware circuit (ie, the external resistor), since the multiplication coefficient K _R in the closed loop remains _unchanged , the proportional coefficient K _C determined by D/A and the driving circuit is proportional to _KY change, and then K _C can be adjusted so that the gain K _f K _C of the modulation channel satisfies K _f K _C 2 ^N = 2π, the analog voltage after the driving circuit is applied to the phase modulator, which just causes the passing light to produce a phase shift of 2πrad .

The present invention has been described in detail above in conjunction with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, various equivalent replacements, modifications or improvements can be made to the technical solutions of the present invention and the embodiments thereof, which all fall within the scope of the present invention. The scope of protection of the present invention is determined by the appended claims.

The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims (10)

1. a digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system, is characterized in that, comprises photodetector, preamplifier circuit, A/D conversion module, closed-loop algorithm central processing unit, D/A conversion module, drive circuit, photoelectric modulation controller, fiber optic ring and scale factor adjustment module; Photoelectric modulator: receives the optical signal sent by the light source, polarizes and modulates the optical signal and sends it to the optical fiber loop; Optical fiber ring: acquire the optical signal from the photoelectric modulator, and send the optical signal to the photoelectric detector through the photoelectric modulator; Photodetector: Receive the optical signal from the optical fiber ring; perform photoelectric conversion processing on the optical signal, generate an electrical signal, and send the electrical signal to the preamplifier circuit; Preamplifier circuit: receives the electrical signal from the photodetector; performs DC blocking and filtering processing on the electrical signal in turn; generates PIN electrical signal; sends the PIN electrical signal to the A/D conversion module; A/D conversion module: receive the PIN electrical signal from the preamplifier circuit; perform analog-to-digital conversion processing on the PIN electrical signal to generate a digital signal; send the digital signal to the closed-loop algorithm central processing unit; Closed-loop algorithm central processing unit: receives the digital signal from the A/D conversion module; performs closed-loop calculation on the digital signal to obtain a digital modulation signal, and sends the digital modulation signal to the D/A conversion module; Proportional coefficient adjustment module: generate the adjustment electrical signal in the D/A conversion module; D/A conversion module: receives the digital modulation signal from the closed-loop algorithm central processing unit, performs digital-to-analog conversion processing on the digital modulation signal under the action of adjusting the electric signal, and generates a feedback electric signal; sends the feedback electric signal to the driving circuit; Drive circuit: receive the feedback electrical signal from the D/A conversion module and amplify it to generate a Y-waveguide modulation signal; send the Y-waveguide modulation signal to the photoelectric modulator; Photoelectric modulator: receives the Y-waveguide modulation signal from the drive circuit, and modulates the phase of the optical signal of the fiber ring according to the Y-waveguide modulation signal, so that the optical signal produces a phase difference. 2 . The digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system according to claim 1 , wherein the adjustment electrical signal is generated in the D/A conversion module by adjusting the equivalent resistance value of the proportional coefficient adjustment module. 3 . 3 . A digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system according to claim 2 , wherein the proportional coefficient adjustment module is a series-parallel resistance network formed by several resistors. 4 . 4. A digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system according to any one of claims 1-3, wherein one end of the proportional coefficient adjustment module is connected to the voltage reference source in the D/A conversion module, and the other is connected to the voltage reference source in the D/A conversion module. One end is connected to the reference ground in the D/A conversion module. 5 . The digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system according to claim 1 , wherein the Y-waveguide modulation signal causes the optical signal of the fiber loop to generate a phase difference of π/2. 6 . 6. A digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system according to claim 1, wherein the proportional coefficient adjustment module generates an adjustment electrical signal in the D/A conversion module so that K _f K _C 2 ^N = 2π, where K _f K _C is the digital closed-loop fiber optic gyro closed-loop proportional coefficient, and N is the number of bits of the register in the D/A conversion module. 7. A digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system according to claim 2, wherein the equivalent resistance value R _SET of the proportional coefficient adjustment module is adjusted according to the PIN electrical signal of the preamplifier circuit, and the specific The method is to adjust the equivalent resistance value R _SET of the proportional coefficient adjustment module so that the PIN electrical signal becomes a straight line. 8. a kind of digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system according to claim 2, is characterized in that, the equivalent resistance value R _SET of described proportional coefficient adjustment module is determined according to following relational formula:

Among them, _VB is the fluctuation amplitude in the PIN electrical signal of the preamplifier circuit, and the empirical formula parameters k and b are obtained by _fitting according to multiple groups of _{VB1, VB2..., R SET1 ,} R _SET2 . 9. A digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment method is characterized in that, a kind of digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment system according to any one of claims 1-8 is realized, it is characterized in that, comprising: The photoelectric modulator receives the optical signal sent by the light source, polarizes and modulates the optical signal, and sends it to the optical fiber loop; The optical fiber loop obtains the optical signal from the photoelectric modulator, and sends the optical signal to the photodetector through the photoelectric modulator; The photodetector receives the optical signal from the optical fiber ring; performs photoelectric conversion processing on the optical signal, generates an electrical signal, and sends the electrical signal to the preamplifier circuit; The preamplifier circuit receives the electrical signal from the photodetector; performs DC blocking and filtering processing on the electrical signal in turn; generates a PIN electrical signal; sends the PIN electrical signal to the A/D conversion module; The A/D conversion module receives the PIN electrical signal from the preamplifier circuit; performs analog-to-digital conversion processing on the PIN electrical signal to generate a digital signal; sends the digital signal to the closed-loop algorithm central processing unit; The closed-loop algorithm central processing unit receives the digital signal from the A/D conversion module; performs closed-loop calculation on the digital signal to obtain a digital modulation signal, and sends the digital modulation signal to the D/A conversion module; The proportional coefficient adjustment module generates the adjustment electrical signal in the D/A conversion module; The D/A conversion module receives the digital modulation signal from the closed-loop algorithm central processing unit, performs digital-to-analog conversion processing on the digital modulation signal under the action of adjusting the electric signal, and generates a feedback electric signal; sends the feedback electric signal to the driving circuit; The drive circuit receives the feedback electrical signal from the D/A conversion module and amplifies it to generate a Y-waveguide modulation signal; sends the Y-waveguide modulation signal to the photoelectric modulator; The photoelectric modulator receives the Y-waveguide modulation signal from the driving circuit, and modulates the phase of the optical signal of the fiber ring according to the Y-waveguide modulation signal, so that the optical signal produces a phase difference. 10. A digital closed-loop fiber optic gyroscope closed-loop proportional coefficient adjustment method according to claim 9, wherein the equivalent resistance value of the proportional coefficient adjustment module is adjusted, and an adjustment electrical signal is generated in the D/A conversion module, and the specific method for: Adjust the equivalent resistance value R _SET of the proportional coefficient adjustment module to make the PIN electrical signal of the preamplifier circuit become a straight line; Or, determine the equivalent resistance value R _SET of the proportional coefficient adjustment module according to the following relationship:

Among them, _VB is the fluctuation amplitude in the PIN electrical signal of the preamplifier circuit, and the empirical formula parameters k and b are obtained by _fitting according to multiple groups of _{VB1, VB2..., R SET1 ,} R _SET2 .

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