Optimization method for distance between double-layer magnetic shielding structures in fiber-optic gyroscope

Abstract

This invention discloses a method for optimizing the distance between double-layer magnetic shielding structures in a fiber optic gyroscope. It solves the technical problem that existing double-layer magnetically shielded fiber optic gyroscopes cannot accurately determine the gap between the two layers of magnetic shielding, leading either to wasted materials and increased weight, or poor anti-magnetic interference capability and reduced accuracy. The method includes the following steps: Step 1: Construct a three-dimensional model; Step 2: Place the three-dimensional model in radial and axial magnetic fields for finite element simulation to obtain the average magnetic field strength of the fiber optic ring in the radial and axial magnetic fields; Step 3: Calculate the maximum output error of the fiber optic gyroscope in the radial and axial magnetic fields; Step 4: Check if the maximum output error of the fiber optic gyroscope meets the technical specifications; Step 5: Output the spacing between the double-layer shielding structures.

Description

Technical Field

[0001] This invention relates to a double-layer magnetically shielded fiber optic gyroscope, specifically to a method for optimizing the distance between the double-layer magnetically shielded structures in a fiber optic gyroscope. Background Technology

[0002] Fiber optic gyroscopes are all-solid-state optoelectronic inertial instruments. They are widely used in inertial navigation systems due to their advantages such as no moving parts, low cost, shock resistance, high sensitivity, long life, large dynamic range, short startup time, and wide accuracy coverage.

[0003] The working principle of a fiber optic gyroscope is based on the Sagnac effect to detect rotational angular velocity. The detection of the Sagnac effect is based on the fact that the interference phase between two counter-propagating light waves in a fiber optic loop should be entirely caused by rotation. However, fiber optic gyroscopes are susceptible to magnetic fields, which can produce non-reciprocal phase differences, affecting the measurement accuracy of the fiber optic gyroscope. To ensure the measurement accuracy of the fiber optic gyroscope, the fiber optic loop is usually magnetically shielded.

[0004] When performing magnetic shielding on fiber optic rings, single-layer or multi-layer magnetic shielding materials are typically used to shield the fiber optic rings in order to reduce the influence of external magnetic fields.

[0005] Among them, single-layer magnetic shielding structures can generally reduce magnetic field interference to a certain extent, but the shielding effect may be insufficient in environments with complex or high-intensity magnetic fields.

[0006] Double-layer magnetic shielding not only compensates for and reduces magnetic leakage between layers, but also offers flexibility in material selection, thickness, and structural arrangement. Furthermore, the spacing between the double-layer magnetic shielding layers affects the output of the fiber optic gyroscope. Different fiber optic gyroscopes utilize varying dimensional parameters such as the inner diameter, outer diameter, width, thickness, and height of the fiber rings, as well as the material properties of the fiber itself, all of which result in different sensitivities to external magnetic fields. However, determining the optimal distance between the double-layer shielding structures remains a key issue that needs to be addressed in this field. On the one hand, an excessively small spacing may lead to excessively strong coupling effects between the shielding materials, resulting in wasted material resources or poor actual shielding performance. On the other hand, an excessively large spacing may increase the overall size and weight of the fiber optic gyroscope, making assembly more difficult, and may also affect the overall structural mechanical strength and installation reliability.

[0007] In existing technologies, the gap between the double-layer magnetic shielding shells is generally adjusted based on the installation space of the fiber optic gyroscope. If the installation space is ample, the gap is maximized to improve the gyroscope's anti-magnetic interference capability. However, this approach wastes production materials and increases the weight of the gyroscope. If the installation space is limited, the gap is minimized to meet installation requirements. However, this approach results in poor anti-magnetic interference capability and reduced accuracy of the fiber optic gyroscope.

[0008] Therefore, accurately and specifically determining the distance between the two layers of magnetic shielding, while meeting the requirements of magnetic shielding materials, spatial arrangement and assembly process, has important engineering application value for improving the anti-magnetic interference capability of fiber optic rings and enhancing the accuracy of fiber optic gyroscopes. Summary of the Invention

[0009] The purpose of this invention is to solve the technical problem that existing double-layer magnetically shielded fiber optic gyroscopes cannot accurately determine the gap between the double magnetic shields, which either leads to material waste and increases the weight of the fiber optic gyroscope, or results in poor anti-magnetic interference capability and reduced accuracy of the fiber optic gyroscope. The invention provides a method for optimizing the distance between the double magnetic shielding structures in a fiber optic gyroscope.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A method for optimizing the distance between double-layer magnetic shielding structures in a fiber optic gyroscope, characterized by the following steps:

[0012] Step 1: Obtain the fiber optic ring assembly of the fiber optic gyroscope to be applied. The fiber optic ring assembly includes a fiber optic ring, an outer shielding structure, and an inner shielding structure. A three-dimensional model of the fiber optic ring assembly is built through simulation. During the construction of the three-dimensional model, the distance between the outer shielding structure and the inner shielding structure is set to a preset distance d to obtain the three-dimensional model of the fiber optic ring assembly.

[0013] Step 2: Obtain the finite element simulation software. Import the 3D model of the fiber optic ring assembly obtained in Step 1 into the finite element simulation software. In the finite element simulation software, set the magnetic properties of the materials of all components in the fiber optic ring assembly. Then, apply radial and axial magnetic fields of preset magnetic field strengths to the 3D model of the fiber optic ring assembly according to the magnetic field environment in which the fiber optic gyroscope will be applied. Simulate and obtain the average value B of the radial magnetic field strength of the fiber optic ring. R and the average value of the axial magnetic field strength of the fiber optic ring B A ;

[0014] Step 3: Based on the average value B of the radial magnetic field strength of the fiber optic ring obtained in Step 2. R and the average value of the axial magnetic field strength of the fiber optic ring B ABased on the wavelength and propagation speed of the incident light from the fiber optic gyroscope, the maximum output error Ω of the fiber optic gyroscope in the radial magnetic field is calculated. R The maximum output error Ω of the fiber optic gyroscope in the axial magnetic field. A ;

[0015] Step 4: Determine the maximum output error Ω of the fiber optic gyroscope in the radial magnetic field obtained in Step 3. R The maximum output error Ω of a fiber optic gyroscope in an axial magnetic field A Does it meet the technical specifications of fiber optic gyroscopes?

[0016] If Ω R ≤ Zero bias stability of fiber optic gyroscope, and Ω A If the zero-bias stability of the fiber optic gyroscope is less than or equal to that of the fiber optic gyroscope, then proceed to step 5.

[0017] If Ω R and Ω A If at least one of the components has a zero-bias stability greater than that of the fiber optic gyroscope, then return to step 1 and increase the spacing between the outer and inner shielding structures to d + Δd, until Ω R and Ω A All are less than or equal to the zero-bias stability of fiber optic gyroscopes;

[0018] Step 5: Output the Ω R and Ω A Correspondingly, the spacing between the outer and inner shielding structures optimizes the distance between the double-layer magnetic shielding structures of the fiber optic gyroscope.

[0019] Furthermore, 0.25mm≤d≤1.5mm, 0.05mm≤Δd≤0.1mm.

[0020] Furthermore, step 3 specifically involves:

[0021] Step 3.1: Based on the average value B of the radial magnetic field strength of the fiber optic ring obtained in Step 2... R The maximum output error Ω of the fiber optic gyroscope in the radial magnetic field was calculated and obtained. R The calculation formula is as follows:

[0022]

[0023] Among them, Ω R This represents the maximum output error of the fiber optic gyroscope in a radial magnetic field, expressed in ° / h.

[0024] R is the equivalent radius of the fiber optic ring, where R = (inner diameter of the fiber optic ring + outer diameter of the fiber optic ring) / 2, in meters; Δβ is the linear birefringence of the fiber itself in the fiber optic ring, in rad / m.

[0025] λ is the wavelength of the incident light from the fiber optic gyroscope, in nm.

[0026] c represents the propagation speed of the incident light in the fiber optic gyroscope, in m / s.

[0027] V is Wilder's constant, with units of rad / m / mT;

[0028] B R This represents the average radial magnetic field strength of the fiber optic ring, in mT.

[0029] t0 is the fiber twist coefficient in the fiber loop, with units of rad / m;

[0030] Step 3.2 Based on the average value B of the axial magnetic field strength of the fiber optic ring obtained in Step 2 A The maximum output error of the fiber optic gyroscope in the axial magnetic field was calculated and obtained.

[0031] Furthermore, step 3.2 specifically includes:

[0032] Based on the average value B of the fiber optic annular axial magnetic field strength obtained in step 2 A The maximum output error of the fiber optic gyroscope in the axial magnetic field is calculated and obtained using the following formula:

[0033]

[0034] Among them, Ω A This represents the maximum output error of the fiber optic gyroscope in an axial magnetic field, expressed in ° / h.

[0035] B A This represents the average axial magnetic field strength of the optical fiber ring, in mT.

[0036] D is the diameter of the optical fiber in the optical fiber ring, in μm.

[0037] Furthermore, the magnetic properties in step 2 include relative linear permeability and relative nonlinear permeability.

[0038] Furthermore, the fiber optic ring assembly in step 1 includes a fiber optic ring, an inner shielding structure, a liner, an outer shielding structure, and screws;

[0039] The inner shielding structure includes an inner top cover and a base. An optical fiber ring is installed inside the base, and the bottom surface of the optical fiber ring is connected to the bottom surface of the inner shielding structure.

[0040] The liner is located inside the inner circle of the inner shielding structure, and the inner and outer shielding structures are fixed to the liner by screws.

[0041] The outer shielding structure includes an outer upper cover and an outer lower cover. The outer upper cover and the outer lower cover together form a receiving cavity, and an inner shielding structure is provided inside the receiving cavity. The two have a common center.

[0042] Furthermore, in step 2, the permeability input to the finite element simulation software includes the relative linear permeability of the fiber ring, the liner, and the screw, as well as the relative nonlinear permeability of the inner shielding structure and the outer shielding structure.

[0043] Compared with the prior art, the present invention has the following beneficial technical effects:

[0044] 1. This invention provides a method for optimizing the distance between double-layer magnetic shielding structures in a fiber optic gyroscope, utilizing the average radial magnetic field strength B of the fiber optic ring obtained through simulation. R and the average value of the axial magnetic field strength of the fiber optic ring B A Based on the basic parameters of the fiber optic gyroscope design, the maximum output error of the fiber optic gyroscope in the axial magnetic field and the maximum output error of the fiber optic gyroscope in the radial magnetic field are calculated. By judging whether the maximum output error of the fiber optic gyroscope in the axial magnetic field and the maximum output error of the fiber optic gyroscope in the radial magnetic field meet the technical specifications of the fiber optic gyroscope, the spacing between the inner shielding structure and the outer shielding structure can be adjusted or output in a timely manner to improve the double-layer magnetic shielding performance of the fiber optic gyroscope.

[0045] 2. This invention provides a method for optimizing the distance between double-layer magnetic shielding structures in a fiber optic gyroscope. It proposes a specific structure for the double-layer magnetic shielding design of the fiber optic gyroscope. By establishing a simulation model and substituting the magnetic field strength data obtained from the simulation into the formula, the maximum output error of the gyroscope in the magnetic field is obtained, thereby achieving a quantitative evaluation of the gyroscope output.

[0046] 3. The present invention provides a method for optimizing the distance between double-layer magnetic shielding structures in a fiber optic gyroscope. This method is highly applicable, accurate in calculation, and can meet the technical requirements of high-precision fiber optic gyroscopes in complex structural designs.

[0047] 4. The present invention provides a method for optimizing the distance between double-layer magnetic shielding structures in a fiber optic gyroscope. Based on the selection and determination of the spacing between the double-layer magnetic shielding structures using this method, not only can production costs be significantly reduced, but also the size and weight of the fiber optic gyroscope product can be reduced as much as possible while ensuring magnetic shielding performance, thereby effectively improving the double-layer magnetic shielding performance of the fiber optic gyroscope. Attached Figure Description

[0048] Figure 1 This is a flowchart of a method for optimizing the distance between double-layer magnetic shielding structures in a fiber optic gyroscope according to the present invention;

[0049] Figure 2 This is a partial cross-sectional view of the three-dimensional model of the fiber optic ring assembly used in an embodiment of the method for optimizing the distance between double-layer magnetic shielding structures in a fiber optic gyroscope according to the present invention.

[0050] Figure 3 for Figure 2Front view of the cross-section at point A;

[0051] Figure 4 This is an exploded view of an optical fiber ring assembly in an embodiment of a method for optimizing the distance between double-layer magnetic shielding structures in an optical fiber gyroscope and improving the performance of double-layer magnetic shielding in an optical fiber gyroscope according to the present invention.

[0052] Figure 5 This is a simulation of the magnetic field distribution of a double-layer magnetically shielded fiber optic ring in a radial magnetic field, representing an embodiment of the distance optimization method between double-layer magnetically shielded structures in a fiber optic gyroscope according to the present invention.

[0053] Figure 6 This is a simulation of the magnetic field distribution of a double-layer magnetically shielded fiber optic ring in an axial magnetic field, representing an embodiment of the distance optimization method between double-layer magnetically shielded structures in a fiber optic gyroscope according to the present invention.

[0054] Figure 7 This is a schematic diagram of the magneto-optical Faraday effect in existing technology.

[0055] Figure 8 The geometric relationship of the fiber optic ring in the radial magnetic field in the formula derivation of the distance optimization method between the double-layer magnetic shielding structures in the fiber optic gyroscope of the present invention;

[0056] Figure 9 The geometric relationship of the fiber optic ring in the axial magnetic field is shown in the formula derivation of the distance optimization method between the double-layer magnetic shielding structures in the fiber optic gyroscope of the present invention.

[0057] The annotations in the attached figures are explained as follows:

[0058] 1. Fiber optic ring; 2. Inner shielding structure; 21. Inner top cover; 22. Base; 3. Outer shielding structure; 31. Outer top cover; 32. Outer bottom cover; 4. Liner plate; 5. Screws. Detailed Implementation

[0059] To make the objectives, advantages, and features of this invention clearer, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a method for optimizing the distance between double-layer magnetic shielding structures in a fiber optic gyroscope. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this invention and are not intended to limit the scope of protection of this invention.

[0060] like Figure 1-9 As shown, a method for optimizing the distance between double-layer magnetic shielding structures in a fiber optic gyroscope includes the following steps:

[0061] Step 1: Obtain the fiber optic ring assembly for the fiber optic gyroscope to be applied. The fiber optic ring assembly includes a fiber optic ring 1, an outer shielding structure 3 (made of 1J79 high permeability alloy), an inner shielding structure 2 (made of 1J79 high permeability alloy), a liner 4 (made of hard aluminum alloy), and screws 5 (made of zinc alloy). The inner shielding structure 2 includes an inner cover 22 and a base 21. The fiber optic ring 1 is disposed inside the base 21, and the bottom surface of the fiber optic ring 1 is connected to the bottom surface of the base 21. The outer shielding structure 3 includes... The assembly includes an outer upper cover 32 and an outer lower cover 31, which together form a receiving cavity. An inner shielding structure 2 is provided inside the receiving cavity, and the two have a common center. A liner 4 is located on the inner circle of the inner shielding structure 2. The inner shielding structure 2 and the outer shielding structure 3 are fixed to the liner 4 by screws 5. A three-dimensional model of the fiber optic ring assembly is built through simulation. During the construction of the three-dimensional model, the distance between the outer shielding structure and the inner shielding structure is set to a preset distance d = 1 mm to obtain the three-dimensional model of the fiber optic ring assembly.

[0062] Step 2: Obtain the finite element simulation software. Import the 3D model of the fiber optic ring assembly obtained in Step 1 into the finite element simulation software. In the finite element simulation software, set the relative linear permeability of fiber optic ring 1 to 1, the relative nonlinear permeability of outer shielding structure 2 as shown in the BH curve parameters in the table below, the relative nonlinear permeability of inner shielding structure 3 as shown in the BH curve parameters in the table below, the relative linear permeability of liner 4 to 1, and the relative linear permeability of screw 5 to 1. Then, apply radial and axial magnetic field strengths of 0.055mT (taking the natural Earth's magnetic field as an example) to the 3D model of the fiber optic ring assembly, and perform two simulations. The simulation result is taken as the average value of the magnetic field strength on the fiber optic ring, and the average value of the radial magnetic field strength B of the fiber optic ring is obtained. R =4.3×10 -7 mT and the average value of the fiber optic annular axial magnetic field strength B A =1.14×10 -5 mT;

[0063] Table BH curve

[0064] H(A / m) B(T) 0.8 0.1000 1.2 0.1750 1.8 0.2750 4.2 0.5334 8 0.5800 9 0.6000 16 0.6500 39.7 0.7561 399.8 0.8002 796.3 0.8013 1200 0.8013 1600 0.8013 2000 0.8013 2400 0.8013 2800 0.8013

[0065] Step 3: Based on the average value B of the radial magnetic field strength of the fiber optic ring obtained in Step 2. R and the average value of the axial magnetic field strength of the fiber optic ring B A The maximum output error Ω of the fiber optic gyroscope in the radial magnetic field was calculated and obtained. R =1.49×10 -5 ° / h, and the maximum output error Ω of the fiber optic gyroscope in the axial magnetic field. A =3.16×10 -7 ° / h; the specific calculation method is as follows:

[0066] Step 3.1: Based on the average value B of the radial magnetic field strength of the fiber optic ring obtained in Step 2... R The general physical parameters related to the fiber optic gyroscope, the equivalent radius of the fiber optic loop, and the average radial magnetic field strength B of the fiber optic loop are analyzed. R Substituting into the calculation formula, the maximum output error Ω of the fiber optic gyroscope in the radial magnetic field is calculated and obtained. R The calculation formula is as follows:

[0067]

[0068] Among them, Ω R This represents the maximum output error of the fiber optic gyroscope in a radial magnetic field, expressed in ° / h.

[0069] In this embodiment, R is the equivalent radius of the fiber optic ring, where R = (inner diameter of the fiber optic ring + outer diameter of the fiber optic ring) / 2, and the unit is m;

[0070] △β represents the linear birefringence of the optical fiber itself in the fiber loop, with units of rad / m;

[0071] λ is the wavelength of the incident light from the fiber optic gyroscope, in nm.

[0072] c represents the propagation speed of the incident light in the fiber optic gyroscope, in m / s.

[0073] V is Wilder's constant, with units of rad / m / mT;

[0074] B R This represents the average radial magnetic field strength of the fiber optic ring, in mT.

[0075] t0 is the fiber twist coefficient in the fiber loop, with units of rad / m;

[0076] Step 3.2: Based on the average value B of the axial magnetic field strength of the fiber optic ring obtained in Step 2... A The general physical parameters related to the fiber optic gyroscope, the equivalent radius of the fiber optic loop, and the average value B of the axial magnetic field strength of the fiber optic loop are analyzed. A Substituting into the calculation formula, the maximum output error of the fiber optic gyroscope in the axial magnetic field is calculated and obtained. The calculation formula is as follows:

[0077]

[0078] Among them, Ω A This represents the maximum output error of the fiber optic gyroscope in an axial magnetic field, expressed in ° / h.

[0079] B A This represents the average axial magnetic field strength of the optical fiber ring, in mT.

[0080] D is the diameter of the optical fiber in the optical fiber ring, in μm.

[0081] Table 1 General physical parameters related to fiber optic gyroscopes

[0082] parameter numerical values △β 2200rad / m λ 1550nm c <![CDATA[3×10 8 m / s]]> V <![CDATA[6×10 -4 rad / m / mT]]> <![CDATA[t0]]> 0.5 rad / m D 150μm R 0.06m

[0083] The derivation of Formula (I) and Formula (II) is as follows:

[0084] The basic principle of a fiber optic gyroscope is the Sagnac effect, which uses the phase difference of interference between two beams of light in a closed loop to sense the external angular rate. The phase difference of interference is expressed as follows:

[0085]

[0086] Where λ is the wavelength of the incident light from the fiber optic gyroscope; c is the propagation speed of the incident light from the fiber optic gyroscope; R is the equivalent radius of the fiber optic ring; L = N·2πR is the path length of the light wave in the fiber optic ring over N turns; and Ω is the rotational angular rate.

[0087] British scholar Michael Faraday first discovered and proposed the magneto-optical Faraday effect in experiments. When light waves propagate through an optical fiber, if the fiber is in a magnetic field, the polarization plane of the light wave will rotate, such as... Figure 7 As shown.

[0088] The Faraday effect relationship is: the magneto-rotation angle θ of the polarization plane of light is related to the path length L of the light wave in the fiber optic loop and the component B of the external magnetic field strength in the direction of light propagation. / / Proportional, that is:

[0089] θ = VB / / L (2)

[0090] Where V is the Verdet constant, with units of (rad / m / mT).

[0091] The rotation of the polarization plane of a light wave means a change in the phase shift of the polarized light, which affects the overall interference effect of the gyroscope and causes errors in the gyroscope.

[0092] By analyzing the polarization state changes of light waves within the fiber optic ring, the phase difference Φ resulting from the magnetic field after the clockwise and counterclockwise light waves converge is:

[0093]

[0094] Where z is the length of the differential fiber, in meters; η + For birefringence in the fiber segment containing the clockwise light wave; η -ξ represents the birefringence of the fiber segment containing the counterclockwise light wave; Δβ represents the linear birefringence of the fiber itself, measured in rad / m; i Circular birefringence caused by the Faraday effect, unit: rad / m; t i represents the circular birefringence caused by fiber twisting, in rad / m; n represents the total number of i, the total number of infinitesimal elements.

[0095] The fiber optic ring is affected by a radially uniform magnetic field, such as Figure 8 As shown, B R Let N represent the intensity of the radial magnetic field, and let θ be the angle between it and the X-axis. Let z be the distance between any point A on the fiber optic ring and the starting point of the fiber optic ring. Let L be the total length of the fiber in the fiber optic ring, and let L = 2πNR, where N is the total number of turns of the fiber and R is the radius of the fiber optic ring.

[0096] For any point A on the fiber optic loop, the radial magnetic field B R At point A, the component of light propagating in the direction parallel to its path is B. R∥ The vertical component is B R⊥ According to the Faraday effect, the parallel component B of the radial magnetic field... R∥ This will induce the magneto-optical Faraday effect, causing magnetic field errors in the fiber optic gyroscope; while the radial magnetic field perpendicular component B R⊥ It will not cause the magneto-optical Faraday effect.

[0097] according to Figure 8 From the geometric relationships, the distribution of circular birefringence caused by the Faraday effect on the optical fiber is as follows:

[0098] ξ(z)=VB R / / =VB R sin(z / R+θ) (4)

[0099] Substituting equation (4) into equation (3) and simplifying, we can obtain the phase difference generated by the radial magnetic field affecting the fiber optic ring as follows:

[0100]

[0101] Where t(z) represents the distribution of circular birefringence caused by fiber twisting on the fiber, with units of rad / m.

[0102] Substituting equation (1) into equation (5), we can obtain the following angular velocity error caused by the radial magnetic field affecting the fiber optic ring:

[0103]

[0104] If the fiber torsion is uniformly distributed along the fiber length, i.e., t(z) is constant, then the integral part in equation (6) is zero, and the fiber ring angular velocity error is zero. If the fiber torsion distribution t(z) along the fiber length is periodic and its period is the same as the period of sin(z / R+θ), then... There will be a maximum value, that is, the angular velocity error caused by the radial magnetic field affecting the fiber optic ring is the largest.

[0105] When t(z) = t0sin(z / R), the maximum angular velocity error is:

[0106]

[0107] Converting the unit rad / s in (7) to ° / h, we obtain the maximum output error Ω of the fiber optic gyroscope. R The formula is as follows:

[0108]

[0109] The fiber optic ring is affected by a uniform axial magnetic field, such as Figure 9 As shown, B A This represents the strength of the axial magnetic field. Figure 9 The right side shows a partial view of the fiber in the fiber loop at the turn-changing position. Previous studies modeled the axial magnetic field error of fiber optic gyroscopes using helically wound fibers. However, with the development of precision winding technology for fiber optic gyroscopes, precision winding methods such as octet symmetric winding and sixteen-pole symmetric winding have been widely used in recent years. These precision symmetric winding methods employ parallel winding, with bending only at fixed positions within each turn of the fiber to complete the turn-changing.

[0110] Let α be the angle between the fiber optic bend and the fiber loop plane. For any point A on the fiber optic bend, the axial magnetic field B... A At point A, the component of light propagating in the direction parallel to its path is B. A / / The vertical component is B A⊥ .

[0111] according to Figure 9 From the geometric relationships, the distribution of circular birefringence caused by the Faraday effect on the optical fiber is as follows:

[0112]

[0113] Where p is the number of layers in the fiber optic ring; D(p) is a function of the number of layers in the fiber optic ring, representing the bending direction of the fiber optic loop change section on each layer, with upward bending and downward bending being positive and negative one, respectively.

[0114] Substituting equation (8) into equation (3), we can obtain the following phase difference generated by the axial magnetic field affecting the fiber optic ring:

[0115]

[0116] Where q is the number of turns per layer of the fiber optic ring, and p·q=N, j represents the ordinal number of the bend section of the fiber optic ring, and L j and L j +s represents the start and end positions of the turn-changing location within the fiber optic ring, and s represents the length of the turn-changing section.

[0117] Substituting equation (1) into equation (9), we can obtain the following angular velocity error of the fiber optic ring due to the influence of the axial magnetic field:

[0118]

[0119] If the fiber twist is uniformly distributed along the fiber length, i.e., t(z) is constant, then the summation part in equation (25) is zero because the total number of upward and downward bending layers in the fiber loop is the same regardless of whether it is an octet, a hexapet, or other multipole winding method. If the fiber twist distribution t(z) along the fiber length is periodic and the period is the same as the period of D(p), then equation (10) will have a maximum value, i.e., the angular velocity error caused by the axial magnetic field affecting the fiber loop is the largest.

[0120] When t(z) = t0D(p), the maximum angular velocity error is:

[0121]

[0122] Converting the unit rad / s in (11) to ° / h, we obtain the maximum output error Ω of the fiber optic gyroscope. A The formula is as follows:

[0123]

[0124] Step 4: Determine the maximum output error Ω of the fiber optic gyroscope in the radial magnetic field obtained in Step 3. R The maximum output error Ω of a fiber optic gyroscope in an axial magnetic field A Does it meet the technical specifications of fiber optic gyroscopes (i.e., the zero-bias stability of fiber optic gyroscopes is 1×10-3)?

[0125] Ω R ≤1×10⁻³, and Ω A ≤1×10-3;

[0126] Step 5: Output the Ω R and Ω A Correspondingly, the distance between the outer and inner shielding structures is 1mm, thus optimizing the distance between the double-layer magnetic shielding structures of the fiber optic gyroscope.

[0127] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection or an integral 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.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. 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 present invention.

Claims

1. A method for optimizing the distance between double-layer magnetic shielding structures in a fiber optic gyroscope, characterized in that, Includes the following steps: Step 1: Obtain the fiber optic ring assembly of the fiber optic gyroscope to be applied. The fiber optic ring assembly includes a fiber optic ring (1), an outer shielding structure (3) and an inner shielding structure (2). A three-dimensional model of the fiber optic ring assembly is built through simulation. During the construction of the three-dimensional model, the distance between the outer shielding structure (3) and the inner shielding structure (2) is set to a preset distance d to obtain the three-dimensional model of the fiber optic ring assembly. Step 2, obtaining a finite element simulation software, importing the three-dimensional model of the fiber coil assembly obtained in step 1 into the finite element simulation software, setting the magnetic property attributes of the materials of all components in the fiber coil assembly in the finite element simulation software, and then respectively applying a preset magnetic field strength radial magnetic field and an axial magnetic field to the three-dimensional model of the fiber coil assembly according to the magnetic field environment applied by the fiber optic gyroscope to be applied, and simulating to obtain the average value B R of the radial magnetic field strength of the fiber coil A and the average value B A of the axial magnetic field strength of the fiber coil. Step 3: Based on the average value B of the radial magnetic field strength of the fiber optic ring obtained in Step 2. R and the average value of the axial magnetic field strength of the fiber optic ring B A Based on the wavelength and propagation speed of the incident light from the fiber optic gyroscope, the maximum output error Ω of the fiber optic gyroscope in the radial magnetic field is calculated. R The maximum output error Ω of the fiber optic gyroscope in the axial magnetic field. A ; Step 4: Determine the maximum output error Ω of the fiber optic gyroscope in the radial magnetic field obtained in Step 3. R The maximum output error Ω of a fiber optic gyroscope in an axial magnetic field A Does it meet the technical specifications of fiber optic gyroscopes? If Ω R ≤ Zero bias stability of fiber optic gyroscope, and Ω A If the zero-bias stability of the fiber optic gyroscope is less than or equal to that of the fiber optic gyroscope, then proceed to step 5. If Ω R and Ω A If at least one of the components has a zero-bias stability greater than that of the fiber optic gyroscope, then return to step 1 and increase the spacing between the outer and inner shielding structures to d + Δd, until Ω R and Ω A All are less than or equal to the zero-bias stability of fiber optic gyroscopes; Step 5: Output the Ω R and Ω A Correspondingly, the spacing between the outer and inner shielding structures optimizes the distance between the double-layer magnetic shielding structures of the fiber optic gyroscope.

2. The method for optimizing the distance between the double-layer magnetic shielding structures in a fiber optic gyroscope according to claim 1, characterized in that, 0.25mm≤d≤1.5mm, 0.05mm≤Δd≤0.1mm.

3. The method for optimizing the distance between the double-layer magnetic shielding structures in a fiber optic gyroscope according to claim 1, characterized in that, Step 3 specifically involves: Step 3.1: Based on the average value B of the radial magnetic field strength of the fiber optic ring obtained in Step 2... R The maximum output error Ω of the fiber optic gyroscope in the radial magnetic field was calculated and obtained. R The calculation formula is as follows: Among them, Ω R This represents the maximum output error of the fiber optic gyroscope in a radial magnetic field, expressed in ° / h. R is the equivalent radius of the fiber optic ring, where R = (inner diameter of the fiber optic ring + outer diameter of the fiber optic ring) / 2, in meters; Δβ is the linear birefringence of the fiber itself in the fiber optic ring, in rad / m. λ is the wavelength of the incident light from the fiber optic gyroscope, in nm. c represents the propagation speed of the incident light in the fiber optic gyroscope, in m / s. V is Wilder's constant, with units of rad / m / mT; B R This represents the average radial magnetic field strength of the fiber optic ring, in mT. t0 is the fiber twist coefficient in the fiber loop, with units of rad / m; Step 3.2 Based on the average value B of the axial magnetic field strength of the fiber optic ring obtained in Step 2 A The maximum output error of the fiber optic gyroscope in the axial magnetic field was calculated and obtained.

4. The method for optimizing the distance between the double-layer magnetic shielding structures in the fiber optic gyroscope according to claim 3, characterized in that, Step 3.2 specifically involves: Based on the average value B of the fiber optic annular axial magnetic field strength obtained in step 2 A The maximum output error of the fiber optic gyroscope in the axial magnetic field is calculated and obtained using the following formula: Among them, Ω A This represents the maximum output error of the fiber optic gyroscope in an axial magnetic field, expressed in ° / h. B A This represents the average axial magnetic field strength of the optical fiber ring, in mT. D is the diameter of the optical fiber in the optical fiber ring, in μm.

5. The method for optimizing the distance between the double-layer magnetic shielding structures in a fiber optic gyroscope according to claim 1, characterized in that: The magnetic properties in step 2 include relative linear permeability and relative nonlinear permeability.

6. The method for optimizing the distance between double-layer magnetic shielding structures in a fiber optic gyroscope according to claim 1, characterized in that: The fiber optic ring assembly in step 1 includes a fiber optic ring (1), an inner shielding structure (2), a liner (4), an outer shielding structure (3), and screws (5); The inner shielding structure (2) includes an inner cover (22) and a base (21). An optical fiber ring (1) is provided inside the base (21), and the bottom surface of the optical fiber ring (1) is connected to the bottom surface of the inner shielding structure (2). The liner (4) is located on the inner circle of the inner shielding structure (2), and the inner shielding structure (2) and the outer shielding structure (3) are fixed on the liner (4) by screws (5); The outer shielding structure (3) includes an outer upper cover (32) and an outer lower cover (31). The outer upper cover (32) and the outer lower cover (31) together form a receiving cavity, and an inner shielding structure (2) is provided inside the receiving cavity. The two have a common center.

7. The method for optimizing the distance between the double-layer magnetic shielding structures in a fiber optic gyroscope according to claim 6, characterized in that: In step 2, the permeability input to the finite element simulation software includes the relative linear permeability of the fiber ring (1), the liner (4) and the screw (5), as well as the relative nonlinear permeability of the inner shielding structure (2) and the outer shielding structure (3).

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