A multi-layer magnetic shielding gyroscope based on strip material and assembly method

Abstract

The present invention discloses a multi-layer magnetically shielded gyroscope based on a strip material and an assembly method, belonging to the field of inertial measurement technology. The multi-layer magnetically shielded gyroscope based on a strip material comprises an upper cover, a lower cover, a gyroscope flange, a magnetically enclosed space, optical components, and a gyroscope circuit board. It can provide magnetic shielding protection for a fiber optic ring and offers advantages such as lightweight, low cost, and the ability to select multiple layers of shielding based on actual needs. During assembly, the new strip material is provided with position-limiting measures, eliminating the need for special treatment at the overlapped joints and the need for adhesive bonding to achieve self-fixation of the strip material, thereby improving the reliability of the strip material application.

Description

Technical Field

[0001] The invention relates to a strip-based multi-layer magnetic shielding gyroscope and an assembly method thereof, belonging to the technical field of inertial measurement. Background Art

[0002] The fiber optic gyroscope is an all-solid-state inertial instrument based on the Sagnac effect. It is used to measure the angular rate of the carrier. It is an important component of the aircraft navigation system and attitude control system, and is an important guarantee for achieving high-precision navigation of the aircraft.

[0003] The Faraday effect affects the accuracy of fiber optic gyroscopes (FOGs) by altering the parameters of lightwaves in the optical path, resulting in output errors manifested as bias drift. FOG applications are subject to geomagnetic and spatial magnetic fields, which can cause errors in the gyroscope. Therefore, magnetic shielding is essential. The primary purpose of FOG magnetic shielding is to suppress the Faraday effect, primarily by shielding the optical path, with the core being the fiber ring.

[0004] Currently, most medium- and high-precision gyros use structural components made of soft magnetic materials (such as Permalloy) as their housings to achieve magnetic shielding. This method is relatively easy to manufacture and provides reliable shielding, making it the most commonly used shielding method. However, this method still has inherent drawbacks:

[0005] (1) High density. The density of commonly used Permalloy is 8.7g / cm 3 , which is about three times that of aluminum alloy 2A12. With the trend of lightweight gyroscopes, the weight of gyroscope structural parts accounts for an increasing proportion, becoming a difficult problem in weight reduction;

[0006] (2) The process is complex. The internal stress of the iron-nickel alloy has a great influence on the magnetic shielding effect. In order to ensure that the Permalloy has an excellent magnetic shielding effect, hydrogen annealing treatment is required after the processing is completed to eliminate the internal stress. Even if the structural parts are repaired locally in a small area, hydrogen annealing is required again.

[0007] (3) Most of them are single-layer shielding. In some high-precision gyroscope designs, double-layer or multi-layer shielding is used, which has a great cost in size and weight.

[0008] (4) The material processing cost and process cost are high, and the production cycle is long, which is not conducive to the development trend of low cost and rapid response. Summary of the Invention

[0009] The present invention aims to overcome the shortcomings of the prior art by providing a multi-layer magnetically shielded gyroscope and assembly method. This structure utilizes multiple layers of magnetically shielding tape to achieve excellent magnetic shielding. Furthermore, the present invention enables lightweight fiber-optic gyroscopes with multi-layer magnetic shielding, reducing the weight of these gyroscopes by over 50% compared to Permalloy components.

[0010] The technical solution of the present invention is:

[0011] A multi-layer magnetic shielding gyroscope based on a strip material includes an upper cover, a lower cover, a gyroscope flange, a magnetically enclosed space, an optical device, and a gyroscope circuit board, wherein:

[0012] The gyro flange, upper cover and lower cover are the main structural parts. The upper cover and lower cover are fixedly connected to the gyro flange respectively to form two physically isolated cavities.

[0013] The optics and gyro circuit board are located in the upper cavity;

[0014] The magnetic shielding space is located in the lower cavity, and the magnetically enclosed space includes a fiber optic ring, a fiber optic ring base, a baffle, n circular shielding plates I, n circular shielding plates II, and n cylindrical shielding plates III, where n is the number of shielding layers and n is any integer between [3, 6]. The fiber optic ring base is fixedly connected to the gyro flange. The three shielding plates are all made of magnetic shielding tape, and a closed magnetic shielding space is formed by overlapping all the shielding plates, enclosing the fiber optic ring, fiber optic ring base, and baffle in this space.

[0015] Preferably, the sizes of shielding pieces I, II and III vary with the shielding layers in which they are located. The diameter length value of the shielding piece I of the i-th layer is A-2(i-1)S, the diameter value of the shielding piece II of the i-th layer is B-2(i-1)S, the circumference value of the end face circular edge of the shielding piece III of the i-th layer is C-6.3(i-1)S, and the height value is D-2(i-1)S, where i is an integer of [1,n], A is the diameter value of the first layer shielding piece I, B is the diameter value of the first layer shielding piece II, C is the circumference value of the end face circular edge of the first layer shielding piece III, D is the height value of the first layer shielding piece III, and S is the thickness value of the magnetic shielding tape, which is the total thickness of the substrate and the insulating film. The relationship between the dimensions is A=B, C=3.14A.

[0016] Preferably, the sizes of the fiber optic ring base and the baffle vary depending on the number of shielding layers. The diameter of the fiber optic ring base is E-2(n-1)S, the outer diameter of the baffle is F-2(n-1)S, and the height of the baffle is G-2(n-1)S. E is the diameter of the fiber optic ring base when the number of shielding layers is 1, F is the outer diameter of the baffle when the number of shielding layers is 1, and G is the height of the baffle when the number of shielding layers is 1. E=F=A-2nS, and the value of DG is greater than the height of the fiber optic ring.

[0017] Preferably, the inner cavity of the lower cavity is cylindrical, the circular shielding plate II is placed on the bottom of the cylindrical cavity near the lower cover, the shielding plate III is placed on the side wall of the cylindrical cavity, the shielding plate I is placed between the gyro flange and the optical fiber ring base, a baffle is placed on the shielding plate II, and the upper and lower ends of the shielding plate III respectively support the shielding plate I and shielding plate II.

[0018] Preferably, a raised rectangular positioning block is provided at the center of the gyro flange, and a matching rectangular positioning groove is provided at the center of the shielding plate 1.

[0019] Preferably, the shielding piece I is evenly pressed by the optical fiber ring base, the shielding piece II is evenly pressed by the baffle, and the shielding piece III is limited at both ends of the overlapping boundary with the shielding piece II by the optical fiber ring base and the baffle side so that the overlapping surfaces do not overlap.

[0020] Preferably, the magnetic shielding strip uses an iron-nickel alloy as a base material, and one side of the strip is provided with an insulating film.

[0021] Preferably, the shielding sheet I, shielding sheet II and shielding sheet III are all formed by machining magnetic shielding strips through forming plates.

[0022] Preferably, the gyro flange, upper cover, lower cover, optical fiber ring base, and baffle are all made of aluminum alloy.

[0023] A method for assembling a multi-layer magnetically shielded gyroscope based on a strip material, comprising:

[0024] (S1) placing n shielding sheets I on the gyro flange in order, starting from the first layer, with the side with the insulating film facing the gyro flange, and the positioning grooves of all circular shielding sheets I passing through the positioning blocks of the gyro flange, where n is any integer between [3, 6]; pressing the optical fiber ring base flatly onto all the shielding sheets I and fixing it to the gyro flange; fixing the optical fiber ring to the optical fiber ring base by gluing, and the optical fiber entering the other end face of the gyro flange at the middle circular ring of the optical fiber ring base;

[0025] (S2) placing the first layer of shielding sheet II on the bottom of the inner cavity of the lower cover, with the side with the insulating film facing the bottom of the inner cavity of the lower cover; placing the first layer of shielding sheet III in the cavity of the lower cover, with the side with the insulating film facing the side of the inner cavity of the lower cover, with one end of the cylindrical shielding sheet III pressing against the shielding sheet II and the other end slightly protruding from the edge of the lower cover; then installing the second layer of shielding sheet II and shielding sheet III in the same manner as the first layer, and repeating this process until n shielding sheets II and n shielding sheets III are installed; pushing the baffle into the cavity of the lower cover to press down all the circular shielding sheets II;

[0026] (S3) After the adhesive between the optical fiber ring and the optical fiber ring base in S1 is cured, the structure assembled in S2 is installed on the gyro flange assembled in S1;

[0027] (S4) The optical device and the gyro circuit board are sequentially mounted on the gyro flange, and after the optical fiber and electrical connections and process fixation are completed, the upper cover is fixed to the gyro flange.

[0028] The advantages of the present invention compared with the prior art are:

[0029] 1) The multi-layer magnetic shielding gyroscope design based on the strip of the present invention is superior to the magnetic shielding effect that can be achieved by the magnetic shielding gyroscope in the prior art, and can meet the requirements of applications with high precision, high magnetic field strength or a large range of magnetic field strength changes.

[0030] 2) The present invention realizes the design of a multi-layer magnetic shield with adjustable number of shielding layers while ensuring that the shape, size and mechanical interface remain unchanged, which is conducive to unified design and meets the different requirements of shielding effects in various applications.

[0031] 3) Under the premise of ensuring the magnetic shielding effect, all supporting structures are made of aluminum alloy, without the need to use soft magnetic materials with high density and high cost. It has the characteristics of lightweight, low cost and simple production. Compared with Permalloy structural parts, the structural weight can be saved by more than 50%.

[0032] 4) The present invention designs a structure that uses a new type of magnetic shielding tape to provide magnetic protection for the optical fiber ring, and each part of the tape is mechanically limited and constrained through structural design. The tape can be assembled even without pasting, which is simple to assemble and has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the appearance of the fiber optic gyroscope of the present invention;

[0034] Figure 2 Schematic diagram of the internal structure of the fiber optic gyroscope of the present invention;

[0035] Figure 3 This is a schematic diagram of the positioning of the shielding plates of each part of the present invention and the magnetic shielding space;

[0036] Figure 4 Schematic diagram of the appearance of the optical fiber ring base and baffle of the present invention;

[0037] Figure 5 This is a schematic diagram of the magnetic shielding seal structure of the present invention;

[0038] Figure 6 The cut-out shapes of the shielding sheets I, II, and III of the present invention;

[0039] Figure 7Schematic diagram of the three-layer magnetic shielding structure in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0041] Figure 1 This is a schematic diagram of the appearance of the fiber optic gyroscope of the present invention. Figure 2 Schematic diagram of the internal structure of the fiber optic gyroscope of the present invention, as shown in FIG. Figure 1 、 Figure 2 As shown, a multi-layer magnetic shielding gyroscope based on a strip material includes a lower cover 1, an upper cover 8, a gyroscope flange 5, an optical device 6, a gyroscope circuit board 7 and a magnetically enclosed space, wherein:

[0042] The gyro flange 5, upper cover 8, and lower cover 1 are the main structural components. The upper cover 8 and lower cover 1 are fixedly connected to the gyro flange 5, forming two closed physical isolation cavities, one on the upper and the other on the lower, providing a protective barrier for the internal optoelectronic devices. The optical device 6 and gyro circuit board 7 are located in the upper cavity, and the gyro circuit board 7 has an external electrical connector. The magnetic shielding space is located in the lower cavity, such as Figure 3 As shown, the magnetically enclosed space includes a fiber ring 2, a fiber ring base 3, a baffle 14, n circular shielding sheets I 4, n circular shielding sheets II 12, and n cylindrical shielding sheets III 13, where n represents the number of shielding layers and can be any number of 3, 4, 5, or 6. The fiber ring is secured to the upper surface of the fiber ring base 3 by adhesive, while the lower surface of the fiber ring base 3 is fixedly connected to the gyro flange 5. All three shielding sheets are made of magnetic shielding tape. The overlapping of all the shielding sheets forms a closed magnetic shielding space, enclosing the fiber ring 2, fiber ring base 3, and baffle 14 within this space, providing magnetic protection for the fiber ring.

[0043] The gyro's lower housing 1, baffle 14, fiber ring base 3, gyro flange 5, and upper housing 8 are all fabricated from aluminum alloy, eliminating the need for dense and expensive soft magnetic materials. This achieves magnetic shielding effectiveness, resulting in lightweight, low-cost, and simple production. The use of magnetic shielding tape reduces the weight of components by over 50% compared to Permalloy components while still meeting magnetic shielding requirements.

[0044] Table 1 shows the dimensions of each layer of shielding sheets.

[0045] Table 1 Shielding sheet dimensions based on the number of shielding layers n

[0046]

[0047] In Table 1, n represents the number of shielding layers, S represents the thickness of the magnetic shielding tape, which includes the total thickness of the base material and the insulating film. A represents the diameter of the first shielding sheet I, B represents the diameter of the first shielding sheet II, C represents the circumference of the end face of the first shielding sheet III, D represents the height of the first shielding sheet III, E represents the diameter of the fiber ring base when the number of shielding layers is 1, and F represents the outer diameter of the baffle when the number of shielding layers is 1. To ensure that the various components cooperate to form a shielded cavity, the following relationship is maintained between the dimensions: A = B, C = 3.14A.

[0048] Figure 4 Figure 1 shows the outer dimensions of the fiber ring base 3 and baffle 14. The dimensions of the fiber ring base 3 and baffle 14 vary depending on the number of shielding layers. For n-layer shielding, the diameter of the fiber ring base 3 is E-2(n-1)S, the outer diameter of the baffle 14 is F-2(n-1)S, and the thickness of the baffle 14 is G-2(n-1)S. E is the diameter of the fiber ring base when there is one shielding layer, F is the outer diameter of the baffle when there is one shielding layer, and G is the height of the baffle when there is one shielding layer. E = F = A-2ns, where DG should include the height of the fiber ring.

[0049] Adjusting the number of magnetic shielding layers requires only changing three structural dimensions, facilitating a universal design and improving the gyro's adaptability to varying magnetic field environments. The maximum number of shielding layers requires a comprehensive consideration of the tape thickness, the actual dimensions of each component, and tolerance allocations to ensure sufficient safety clearance between components after installation. This ensures a minimum of 1mm between the fiber ring and the outer edge of the magnetic shielding space to prevent contact due to tolerances or vibration, which could affect the ring's accuracy.

[0050] Figure 5 This is a schematic diagram of the magnetic shielding seal structure of the present invention. After the gyro is installed, the circular shielding piece I 4, circular shielding piece II 12, and shielding piece III 13 overlap to form a complete magnetic shielding space, placing the fiber ring 2, fiber ring base 3, and baffle 14 within the magnetic shielding protection space. The circular shielding piece I 4 has a rectangular positioning groove in the center. When installed on the gyro flange 5, it mates with the raised positioning block on the gyro flange 5, ensuring the angular and positioning accuracy of the circular shielding piece I 4. The upper and lower ends of the shielding piece III 13 respectively support the outer circumference of the circular shielding piece I 4 and circular shielding piece II 12. Under the structural constraints of the gyro flange 5 and the lower cover 1, a certain pressure is exerted between the shielding piece III 13 and the circular shielding pieces I 4 and II 12, thereby ensuring magnetic sealing at the overlapping joints. This ensures effective overlapping at the edges through structural tolerance control, resulting in simple operation, good overlapping effect, and easy inspection.

[0051] Figure 3 The positioning and securing relationships of the various shielding pieces are also shown. The circular shielding piece I 4 is precisely positioned by aligning its central positioning slot with the positioning block on the gyro flange 5. Uniform pressure from the gyro flange 5 and the fiber optic ring base 3 ensures its complete securement. When the circular shielding piece II 12 is inserted into the cavity bottom of the lower housing 1, it is precisely positioned by the sidewalls of the lower housing 1. After the shielding piece III 13 and baffle 14 are installed, the circular shielding piece II 12 is fully secured under the pressure of the baffle 14 and the cavity bottom of the lower housing 1. After the shielding piece II 12 is inserted into the cavity bottom of the lower housing 1, the shielding piece III 13 is installed into the side surface of the lower housing 1, controlled by tolerances to ensure close contact with the side surface of the lower housing 1, with the overlapped joints tightly aligned and non-overlapping. The baffle 14 is pressed against the circular shielding piece II 12 by the fiber optic ring base 3. After entering the lower cover cavity, the baffle 14 and the base portion of the optical fiber ring base 3 will form a certain pressure on the overlapping portion of the shielding piece III 13 to ensure that the overlapping portion of the shielding piece III 13 does not overlap, thereby achieving the fixation of the shielding piece III 13.

[0052] The present invention designs a structure for magnetically protecting an optical fiber ring using a novel magnetic shielding tape, which can achieve mechanical limitation and constraint of the tape through structural design. The tape can be assembled without pasting, and has simple assembly and high reliability.

[0053] The magnetic shielding tape needs to be cut and fixed before installation. The magnetic shielding tape can be hydrogen annealed before forming. Subsequent cutting and fixing have little effect on the magnetic shielding performance of the tape itself, and re-hydrogen annealing is not necessary. Figure 6 This is the shape of the magnetic shielding tape of the present invention after cutting and bending. The tape is based on an iron-nickel alloy with a thickness of 0.05mm to 0.2mm. This tape has the same magnetic shielding properties as Permalloy, but also has good toughness and can be bent into a variety of simple shapes. An insulating film is applied to one side of the tape. This film serves to isolate the shielding layers and to provide a certain amount of compression, providing a certain amount of preload for restraining and securing the tape, ensuring effective installation and sealing. The magnetic shielding tape is formed into a specific shape using a forming machine. Compared to laser cutting, this forming method has better cross-sectional quality and dimensional accuracy.

[0054] The specific assembly method is as follows:

[0055] (S1) Place n shielding sheets (1) onto the gyro flange in order, starting with the first layer, with the side with the insulating film facing the gyro flange. The positioning grooves of all circular shielding sheets (1) pass through the positioning blocks of the gyro flange. The positioning grooves of the circular shielding sheets (1 to 4) and the positioning blocks of the gyro flange (5) ensure precise positioning of the circular shielding sheets (1 to 4). Then, press the fiber optic ring base (3) evenly onto all the shielding sheets (1 to 4) and secure it to the gyro flange (5) with screws, forming a single unit. Secure the fiber optic ring (2) to the fiber optic ring base (3) by gluing. The optical fiber enters the other end face of the gyro flange (5) at the center circular ring of the fiber optic ring base (3).

[0056] (S2) The first shielding sheet II 12 is placed at the bottom of the inner cavity of the lower cover 1, with the side with the insulating film facing the bottom of the inner cavity of the lower cover 1. The rectangular shielding sheet is bent into a cylindrical shielding sheet III 13 in the shape of the inner side of the lower cover 1. The first shielding sheet III 13 is placed in the cavity of the lower cover 1, with the side with the insulating film facing the outer side of the cylinder, that is, facing the inner side of the lower cover 1. One end of the cylindrical shielding sheet III 13 presses against the shielding sheet II 12, and the other end slightly protrudes from the edge of the lower cover 1. Through tolerance control, the two short sides of the shielding sheet III 13 are aligned but not overlapped. At this time, the shielding sheet III 13 is locked inside the lower cover 1 due to the constraints of the lower cover 1 and its own stress. Then install the second layer of shielding sheets II 12 and III 13 according to the method of the first layer, and repeat this process until n shielding sheets II 12 and n shielding sheets III 13 are installed; then push the baffle 14 into the cavity of the lower cover 1 to press all the circular shielding sheets II 12.

[0057] (S3) After the adhesive between the optical fiber ring and the optical fiber ring base in S1 is cured, the structure assembled in S2 is installed on the gyro flange 5 assembled in S1 to form the lower cavity of the gyro, providing physical isolation, electromagnetic protection and magnetic shielding protection layer for the optical fiber ring.

[0058] (S4) The optical device 6 and the gyro circuit board 7 are sequentially mounted on the gyro flange 5. After the optical fiber and electrical connections and process fixation are completed, the upper cover 8 is fixed to the gyro flange 5 to form the upper cavity of the gyro, providing physical isolation and electromagnetic protection layer for the optical device 6 and the gyro circuit board 7.

[0059] Based on the design of the present invention, a three-layer magnetic shielding gyroscope based on strip material was manufactured. Figure 7This diagram shows the three-layer magnetic shielding structure. The gyro's lower cover 1, baffle 14, fiber ring base 3, gyro flange 5, and upper cover 8 are all machined from aluminum alloy. The shielding tape thicknesses are S = 0.1mm, A = B = 48mm, C = 150.7mm, E = F = 47.4mm, D = 16.4mm, and G = 1.6mm. Testing has shown that this gyro achieves superior magnetic shielding compared to Permalloy components.

[0060] The above description is only the best specific implementation method of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

[0061] The contents not described in detail in the specification of the present invention belong to the common knowledge of professionals in this field.

Claims

1. A multi-layer magnetic shielding gyroscope based on a strip material, characterized in that: It includes an upper cover, a lower cover, a gyro flange, a magnetically enclosed space, optical devices, and a gyro circuit board, among which: The gyro flange, upper cover and lower cover are the main structural parts. The upper cover and lower cover are fixedly connected to the gyro flange respectively to form two physically isolated cavities. The optics and gyro circuit board are located in the upper cavity; The magnetic shielding space is located in the lower cavity, and the magnetically enclosed space includes a fiber ring, a fiber ring base, a baffle, n circular shielding plates I, n circular shielding plates II, and n cylindrical shielding plates III, where n is the number of shielding layers and is any integer between 3 and 6. The fiber ring base is fixedly connected to the gyro flange. The three shielding plates are all made of magnetic shielding tape, and all the shielding plates are overlapped to form a closed magnetic shielding space, enclosing the fiber ring, fiber ring base, and baffle within this space. The sizes of shielding pieces I, II and III vary with the shielding layers they are in. The diameter length of shielding piece I in the i-th layer is A-2(i-1)S, the diameter of shielding piece II in the i-th layer is B-2(i-1)S, the circumference of the end face of shielding piece III in the i-th layer is C-6.3(i-1)S, and the height is D-2(i-1)S, where i is an integer from [1, n], A is the diameter of shielding piece I in the first layer, B is the diameter of shielding piece II in the first layer, C is the circumference of the end face of shielding piece III in the first layer, D is the height of shielding piece III in the first layer, and S is the thickness of the magnetic shielding tape. The relationship between the sizes is A=B, C=3.14A. Shielding piece I is evenly pressed by the fiber optic ring base, shielding piece II is evenly pressed by the baffle, and shielding piece III is limited at both ends of the overlapping boundary with shielding piece II by the fiber optic ring base and the baffle side respectively, so that the overlapping surfaces do not overlap; Shielding sheet I, shielding sheet II and shielding sheet III are all made by machining magnetic shielding strips through forming plates.

2. The multi-layer magnetic shielding gyroscope based on a strip material according to claim 1, characterized in that: The sizes of the fiber optic ring base and baffle vary depending on the number of shielding layers. The diameter of the fiber optic ring base is E-2(n-1)S, the outer diameter of the baffle is F-2(n-1)S, and the height of the baffle is G-2(n-1)S. E is the diameter of the fiber optic ring base when the number of shielding layers is 1, F is the outer diameter of the baffle when the number of shielding layers is 1, and G is the height of the baffle when the number of shielding layers is 1. E=F=A-2nS, and the value of DG must be greater than the height of the fiber optic ring.

3. The multi-layer magnetic shielding gyroscope based on a strip material according to claim 1, characterized in that: The inner cavity of the lower cavity is cylindrical. The circular shielding piece II is placed at the bottom of the cylindrical cavity near the lower cover, the shielding piece III is placed on the side wall of the cylindrical cavity, the shielding piece I is placed between the gyro flange and the optical fiber ring base, a baffle is placed on the shielding piece II, and the upper and lower ends of the shielding piece III respectively support the shielding piece I and the shielding piece II.

4. The multi-layer magnetic shielding gyroscope based on a strip material according to claim 3, characterized in that: There is a raised rectangular positioning block at the center of the gyro flange, and a matching rectangular positioning groove is opened at the center of the shielding plate 1.

5. The multi-layer magnetic shielding gyroscope based on a strip material according to claim 1, characterized in that: The magnetic shielding strip material adopts an iron-nickel alloy as a base material, and an insulating film is provided on one side of the strip material.

6. The multi-layer magnetic shielding gyroscope based on a tape according to any one of claims 1 to 5, characterized in that: The gyro flange, upper cover, lower cover, optical fiber ring base and baffle are all made of aluminum alloy.

7. A method for assembling a multi-layer magnetic shielding gyroscope based on a strip, characterized in that: include: (S1) placing n shielding sheets I on the gyro flange in order, starting from the first layer, with the side with the insulating film facing the gyro flange, and the positioning grooves of all circular shielding sheets I passing through the positioning blocks of the gyro flange, where n is any integer between [3, 6]; pressing the optical fiber ring base flatly onto all the shielding sheets I and fixing it to the gyro flange; fixing the optical fiber ring to the optical fiber ring base by gluing, and the optical fiber entering the other end face of the gyro flange at the middle circular ring of the optical fiber ring base; (S2) placing the first layer of shielding sheet II on the bottom of the inner cavity of the lower cover, with the side with the insulating film facing the bottom of the inner cavity of the lower cover; placing the first layer of shielding sheet III in the cavity of the lower cover, with the side with the insulating film facing the side of the inner cavity of the lower cover, with one end of the cylindrical shielding sheet III pressing against the shielding sheet II and the other end slightly protruding from the edge of the lower cover; then installing the second layer of shielding sheet II and shielding sheet III in the same manner as the first layer, and repeating this process until n shielding sheets II and n shielding sheets III are installed; pushing the baffle into the cavity of the lower cover to press down all the circular shielding sheets II; (S3) After the adhesive between the optical fiber ring and the optical fiber ring base in S1 is cured, the structure assembled in S2 is installed on the gyro flange assembled in S1; (S4) The optical device and the gyro circuit board are sequentially mounted on the gyro flange, and after the optical fiber and electrical connections and process fixation are completed, the upper cover is fixed to the gyro flange.

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