Three-component FBG vibration sensor and use method

Abstract

The invention relates to the technical field of optical fiber sensing, in particular to a three-component FBG vibration sensor and a use method. Comprising a polymer block and an FBG which are integrally formed, a three-dimensional coordinate system is constructed by taking the geometric center of a rectangular base as an original point, and the rectangular base is provided with an x axial surface, a y axial surface and a z axial surface; the two flexible hinges are respectively connected to the x axial surface and are symmetrical about the yoz reference surface; the two first mass blocks are respectively connected with the end face of the flexible hinge. Tail fibers of the two FBGs parallel to the x axis are connected to the surfaces of the first mass blocks to form a y-direction vibration detection module and a z-direction vibration detection module. The cantilever beam is connected to any y axial surface, the second mass block is connected with the end face of the cantilever beam, and a tail fiber of the FBG parallel to the y axis is connected to the surface of the second mass block and the x axial surface of the rectangular base to form an x-direction vibration detection module. The sensor provided by the invention has the advantages of low mass, no assembly error, strong magnetism resistance and the like, and realizes the sensing characteristics of high sensitivity and high inherent frequency under the condition of limited volume.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber sensing technology, and in particular to a three-component FBG vibration sensor and a use method thereof. Background Art

[0002] Traditional vibration sensors designed based on electrical principles are not suitable for harsh environments such as strong electromagnetic fields, oil pollution or corrosion. The FBG in the vibration sensor based on Fiber Bragg Grating (FBG) is an optical sensing component formed by introducing periodic refractive index modulation in the optical fiber. It has the advantages of anti-electromagnetic interference, corrosion resistance and easy multi-sensor multiplexing, and is suitable for working in harsh environments.

[0003] At present, there are two solutions to solve the three-dimensional vibration test problem based on FBG vibration sensors: one is to place one-dimensional sensors in three mutually orthogonal directions, such as the x, y and z directions of the rectangular coordinate system. This solution only requires the design of a one-dimensional sensor, which is relatively simple, but requires the use of three sensors at the same time, and finally synthesizes the acceleration vectors in each direction into a spatial acceleration. Its disadvantages are strict requirements for assembly and matching of each module, large size and complex structure. Another solution is a three-component integrated sensor, which uses a mass block or a mass block connected to an integral body in combination with the sensor structure to transmit the information of each component to the FBG sensor. It can achieve real-time measurement at the same point, with high accuracy and easy use.

[0004] The three-component FBG vibration sensor in the prior art has the following defects: (1) The design of the mass block of the FBG acceleration vibration sensor basically adopts high-density metal materials (such as steel materials). However, various metal mass blocks are easily damaged in harsh environments such as strong magnetism, humidity, acid and alkali. They are not suitable for vibration monitoring in particularly harsh environments such as strong magnetism, strong corrosion, humidity, acid and alkali, which affects the performance of the sensor. Therefore, the selection of metal mass blocks itself weakens the advantages of optical fiber sensors as non-metallic material sensors in adapting to harsh environments and being light in weight.

[0005] (2) The design of FBG acceleration vibration sensors basically uses high-density metal materials (such as steel materials). Sensors made in this way generally require the processing of multiple parts, and then the parts are combined by fastening bolts. This assembly method has the problem of high precision requirements and the fasteners are prone to loosening, which affects the sensing characteristics. (3) Existing low-density non-metallic polymer FBG vibration sensors are all one-dimensional sensors. Simply expanding one dimension to three dimensions will be limited by the structure and have large cross-sensitivity, resulting in low test accuracy.

[0006] (4) When the mass of the sensor itself is large, when the volume and mass of the object to be measured are small, there is a risk that the large mass of the sensor itself will affect the vibration characteristics of the object to be measured, thereby causing a large measurement error.

[0007] (5) All the reported multi-dimensional sensors are made of high-density metal materials, which are different from the environmental adaptability of the present invention and are not suitable for vibration monitoring in particularly harsh environments such as strong magnetism, strong corrosion, humidity, acid and alkali. Summary of the invention

[0008] The present invention aims to at least improve one of the technical problems existing in the prior art. To this end, the present invention proposes a three-component FBG vibration sensor and a method of using the same.

[0009] The three-component FBG vibration sensor according to the first embodiment of the present invention includes a FBG, and further includes: An integrally formed polymer block, the polymer block comprising: A rectangular base, wherein a three-dimensional coordinate system is constructed with the geometric center of the rectangular base as the origin, the rectangular base has an x-axial surface, a y-axial surface and a z-axial surface, and a through hole is opened on the x-axial surface; Two flexible hinges, connected to the x-axis plane of the base surface and symmetrical about the yoz reference plane, have two rotational degrees of freedom, one for measuring the acceleration in the y direction, the movement mode is rotation around the z axis, and the other for measuring the acceleration in the z direction, the movement mode is rotation around the y axis; Two first mass blocks are respectively connected to the end faces of the flexible hinges, and the pigtails of the FBGs parallel to the x-axis are connected to the surfaces of the first mass blocks to form a y-direction vibration detection module and a z-direction vibration detection module; A cantilever beam connected to any y-axis surface; The second mass block is connected to the end face of the cantilever beam, and the pigtail of the FBG parallel to the y-axis is connected to the surface of the second mass block and the x-axial surface of the rectangular base to form an x-direction vibration detection module.

[0010] In a possible implementation manner of the first aspect, the polymer block further includes: Two trapezoidal transition blocks have a first connecting end face and a second connecting end face parallel to each other, wherein the first connecting end face is adaptively connected to the flexible hinge end face, the second connecting end face is adaptively connected to the first mass block end face, and the area of ​​the second connecting end face is larger than that of the first connecting end face.

[0011] In a possible implementation of the first aspect, the entire structure of the polymer block is symmetrical about the xoy reference plane and the yoz reference plane, respectively. There are two reasons for this. One is to facilitate the installation of the FBG, and the other is to maintain strict consistency between the vibration modes of the sensor in the x, y, and z directions and the directions of the x-axis, y-axis, and z-axis.

[0012] In a possible implementation of the first aspect, viewed from the yoz plane, the width of the first mass block in the z direction is greater than the width of the rectangular base in the z direction, which facilitates the installation of the FBG and avoids interference caused by the edge of the base when sensing signals in the y and z directions.

[0013] In a possible implementation manner of the first aspect, the height of the first mass block is consistent with the height at the center of the through hole, and the geometric center of the through hole is located on the y-axis, and the FBG passes through the through hole and is respectively connected to the surface of the first mass block.

[0014] In a possible implementation manner of the first aspect, the surface of the second mass block on which the FBG is mounted and the x-axial plane of the rectangular base are located in the same plane.

[0015] In a possible implementation of the first aspect, the flexible hinge is a co-located orthogonal composite notch-type flexible hinge, and the four sides are overall an asymmetric arc-cut structure. Specifically, the notch of the flexible hinge is cut using an arc, and the thickness and notch radius of the thinnest part of the flexible hinge in the y and z directions are different, so that the structure is asymmetric.

[0016] In a possible implementation manner of the first aspect, the FBG includes: A first FBG, wherein the first FBG pigtails are respectively mounted on the rectangular base and the second mass block, and the first FBG is consistent with the y-axis direction; a second FBG, wherein the second FBG passes through the through holes and is respectively connected to the surface of the first mass block, and the second FBG is consistent with the x-axis direction; A third FBG, wherein the third FBG pigtails are respectively connected to the surface of the first mass block, and the third FBG is consistent with the x-axis direction.

[0017] In a possible implementation manner of the first aspect, the through hole is opened on the x-axial surface close to the cantilever beam side.

[0018] According to the three-component FBG vibration sensor of the embodiment of the present invention, the mass block is formed based on polymer integral molding, which has the advantages of low mass, no assembly error, high temperature resistance, strong magnetic resistance, corrosion resistance, etc. It is not only suitable for vibration monitoring in harsh environments, but also can achieve high sensitivity and high natural frequency sensing characteristics under limited volume conditions. Specifically, the sensor of the present invention uses a low mass density polymer with the characteristics of low mass and small volume, but the sensitivity and natural frequency still reach a high level. The present invention uses a polymer as a mass block to make the FBG three-component vibration sensor a fully non-metallic material, which is more suitable for vibration testing in harsh environments such as strong magnetic fields, acid and alkali, and humidity. The present invention uses a reasonable structural design, uses a low-density polymer, and integrates the mass block and the sensing structure into one, which effectively avoids errors caused by assembly and improves the stability of the sensor performance. Finally, by optimizing the design of the mass block and the sensor structure, a three-component vibration sensor with high sensitivity and high natural frequency is realized.

[0019] According to a second aspect of an embodiment of the present invention, a method for using a three-component FBG vibration sensor is provided, wherein the three-component FBG vibration sensor is used to measure an object to be measured, comprising the following steps: Step S100, the sensitivity of the packaged three-component FBG vibration sensor in the x, y, and z directions is tested to obtain the relationship between the central wavelength offset of the FBG in the x, y, and z directions and the acceleration in each direction, and then obtain the sensitivity matrix. The relationship between the acceleration of the sensor in the x, y, and z directions and the change in the central wavelength of the FBG is as follows: , in, They are respectively represented as the central wavelength changes of the first FBG, the second FBG, and the third FBG, Respectively represent the acceleration applied in the x, y, and z directions; is the sensitivity matrix, where: It is expressed as the sensitivity of the sensor in the x direction when the x-direction vibration is applied. It represents the cross-coupling interference sensitivity in the y direction when the acceleration in the x direction is applied. It represents the cross-coupling interference sensitivity in the z direction when the acceleration in the x direction is applied; It is expressed as the cross-coupling interference sensitivity of the sensor in the x direction when vibration in the y direction is applied. It indicates the sensitivity felt in the y direction when the y direction acceleration is applied. It represents the cross-coupling interference sensitivity in the z direction when the acceleration in the x direction is applied; It is expressed as the cross-coupling interference sensitivity of the sensor in the x direction when vibration in the z direction is applied. It represents the cross-coupling interference sensitivity in the y direction when the z-direction acceleration is applied. It indicates the sensitivity felt in the z direction when the z-direction acceleration is applied; Step S200, fixing the surface of the rectangular base (10) away from the cantilever beam (12) on the surface of the object to be measured; Step S300: When the object under test is vibrated, the central wavelength offsets of the three FBGs are collected. , , ; Step S400, the sensitivity matrix of the sensor is measured according to step S100, which is given by the following relationship: , The acceleration in each direction can be obtained, where is the inverse matrix of the sensitivity matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is a diagram of the mechanism of the FBG-based vibration sensor; Figure 2 is an overall schematic diagram of a three-component FBG vibration sensor according to an embodiment of the present invention; Figure 3 is a schematic structural diagram of a three-component FBG vibration sensor according to an embodiment of the present invention; Figure 4 is a schematic diagram of a flexible hinge of a three-component FBG vibration sensor according to an embodiment of the present invention; Figure 5 is a schematic diagram of a flexible hinge design of a three-component FBG vibration sensor according to an embodiment of the present invention; Figure 6 Schematic diagram of the flexible hinge of the three-component FBG vibration sensor according to the embodiment of the present invention from different viewing angles.

[0022] Reference numerals: polymer block 1, FBG2; Rectangular base 10 , through hole 101 , flexible hinge 11 , cantilever beam 12 , first mass block 13 , second mass block 14 , trapezoidal stage transition block 15 , first connection end face 151 , second connection end face 152 .

[0023] The first FBG 21 , the second FBG 22 , and the third FBG 23 . DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0025] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0027] The terms "first", "second", "third", etc. in the specification and claims of the present application and the drawings are used to distinguish different objects rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a series of steps or units are included, or optionally, steps or units not listed are included, or optionally, other steps or units inherent to these processes, methods, products or devices are included.

[0028] Only the part relevant to the present application is shown in the accompanying drawings, but not all of the content. Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processing or methods depicted as flow charts. Although the flow chart describes each operation (or step) as a sequential process, many of the operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of each operation can be rearranged. When its operation is completed, the process can be terminated, but it can also have additional steps not included in the accompanying drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0029] The terms "component", "module", "system", "unit", etc. used in this specification are used to represent computer-related entities, hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a unit can be, but is not limited to, a process running on a processor, a processor, an object, an executable file, an execution thread, a program, and / or distributed between two or more computers. In addition, these units can be executed from various computer-readable media having various data structures stored thereon. Units can communicate through local and / or remote processes, for example, based on signals having one or more data packets (e.g., data from a second unit interacting with another unit in a local system, a distributed system, and / or a network. For example, the Internet interacts with other systems via signals).

[0030] Vibration sensors have important use value in health monitoring fields such as earthquake monitoring, geological disaster warning, power systems, oil and mine exploration. In many applications, the sensor is located in a harsh environment, such as the humid environment in oil and mines, and the strong magnetic field environment in the power system. The present invention designs a three-component vibration sensor based on Bragg fiber grating. The acceleration vibration sensor can effectively capture vibration signals in the three directions of x, y, and z, and has the advantages of being suitable for a variety of harsh environments, high sensitivity, light weight, and simple manufacturing.

[0031] The mechanism of FBG-based vibration sensor is as follows Figure 1 As shown. Mass block ,spring and dampers The housing is connected to the test piece, wherein the lower surface of the housing is fixed on the test piece.

[0032] Its sensitivity expression is: (1), in Indicates the sensitivity of the sensor. is the central wavelength of the FBG reflected light, is the changing central wavelength, is the acceleration applied to the sensor, is the elastic modulus of the optical fiber, is the cross-sectional area of ​​the optical fiber.

[0033] Vibration is a vector. To detect vibration information in all directions, a three-dimensional vibration sensor is needed. There are currently two solutions to solve the three-dimensional vibration test problem based on FBG vibration sensors: one is to place one-dimensional sensors in three mutually orthogonal directions, such as the x, y and z directions of the rectangular coordinate system. This solution only requires the design of a one-dimensional sensor, which is relatively simple, but requires the use of three sensors at the same time. Finally, the acceleration vectors in each direction are synthesized into spatial acceleration. The disadvantage is that the assembly and matching requirements of each module are strict, the volume is large, and the structure is complex. Another solution is a three-component integrated sensor, which uses a mass block or a mass block connected to an integral body in combination with the sensor structure to transmit the information of each component to the FBG sensor. It can achieve real-time measurement at the same point, with high accuracy and easy use.

[0034] The performance improvement of existing three-component integrated sensors is limited by many factors. First, as shown in formula (1), the sensitivity of the FBG three-component integrated vibration sensor is proportional to the mass of the mass block. Therefore, in order to achieve higher sensitivity, the mass block in the sensor is either large in size or made of high-density metal materials, such as manganese 65, tantalum, stainless steel, etc. Large sensors are limited in space during installation and have limited use. Moreover, various metal mass blocks are easily damaged in harsh environments such as strong magnetism, humidity, acid and alkali, which affects the performance of the sensor. Therefore, their use itself weakens the advantages of optical fiber sensors as non-metallic material sensors in adapting to harsh environments and being light in weight. On the other hand, the use of metal blocks places high demands on their precision processing and assembly, especially for three-component sensors. Existing three-component FBG sensors with metal materials as mass blocks often need to process each component separately and then undergo precision assembly. For example, the conventional assembly method is to connect the various parts with fasteners such as screws. Therefore, the performance indicators of the sensor are affected by the processing accuracy and assembly level of each component, and the performance may be affected by the loosening of the fasteners in the connection part during vibration sensing. Finally, although there have been reports on the development of FBG vibration sensors using low-density non-metallic polymers, they are all one-dimensional sensors. Simply expanding one dimension to three dimensions will be limited by the structure and have large cross-sensitivity, resulting in low test accuracy.

[0035] In view of the above problems, the present invention proposes a three-component FBG vibration sensor, which is based on a polymer integrally molded mass block, and has the advantages of low mass, no assembly error, high pressure resistance, strong magnetism resistance, corrosion resistance, etc. It is not only suitable for vibration monitoring in harsh environments, but also can achieve high sensitivity and high working frequency band sensing characteristics under limited volume conditions. First, the sensor of the present invention uses low-mass and low-density polymers and has a relatively high sensitivity and natural frequency under the premise of a small volume. Secondly, the use of polymer material mass blocks can make the FBG three-component vibration sensor a fully non-metallic material, which is more suitable for vibration testing in harsh environments such as strong magnetic fields, acid and alkali, and humidity. Thirdly, the present invention uses a low-density polymer material through a reasonable structural design, and the mass block and the sensing structure are integrally molded, which effectively avoids errors caused by assembly and improves the stability of the sensor performance. Finally, by optimizing the design of the mass block and the sensor structure, a three-component sensor with high sensitivity and high natural frequency is realized.

[0036] See the following examples for details.

[0037] Example 1 See also Figure 2 and Figure 3 As shown, the three-component FBG vibration sensor of this embodiment includes FBG2, which also includes: An integrally formed polymer block 1, the polymer block 1 comprising: A rectangular base 10, wherein a three-dimensional coordinate system is constructed with the geometric center of the rectangular base 10 as the origin, the rectangular base 10 has an x-axial surface, a y-axial surface and a z-axial surface, and a through hole 101 is opened on the x-axial surface; Two flexible hinges 11, respectively connected to the x-axis plane and symmetrical about the yoz reference plane, have two rotational degrees of freedom, one for measuring the acceleration in the y direction, and its movement mode is rotation around the z axis, and the other for measuring the acceleration in the z direction, and its movement mode is rotation around the y axis; Two first mass blocks 13 are respectively connected to the end faces of the flexible hinge 11 away from the x-axis plane, and the pigtails of the FBG parallel to the x-axis are connected to the surfaces of the first mass blocks 13 to form a y-direction vibration detection module and a z-direction vibration detection module; A cantilever beam 12 connected to any y-axial surface; The second mass block 14 is connected to the end face of the cantilever beam 12 away from the y-axis plane, and the pigtail of the FBG parallel to the y-axis is connected to the surface of the second mass block 14 and the x-axis plane of the rectangular base 10 to form an x-direction vibration detection module.

[0038] It should be noted that the first mass block 13 and the second mass block 14 are both rectangular mass blocks, and the two first mass blocks 13 have the same structure and are symmetrical in position with the yoz reference plane. There are two reasons for this. One is to ensure that the vibration modes of the sensor in the x, y, and z directions are symmetrical, so that the second FBG22 and the third FBG23 can better sense the vibration signals from the y and z directions. The second is that when the sensor is under the same acceleration, the asymmetric mass blocks on both sides will increase the bending of the FBG along the axial direction, thereby increasing the bending loss of the optical fiber, which is not conducive to the stability of the FBG sensor signal, and the symmetrical mass block structure avoids this situation. In addition, the rectangular mass block structure can be combined with the characteristics of the biaxial flexible hinge on the one hand to form a vibration that can withstand different loads. The combination of the cylindrical mass block and the biaxial flexible hinge will cause stress concentration due to the discontinuous structure.

[0039] It should be noted that the polymer block 1 also includes: The two trapezoidal transition blocks 15 have a first connecting end face 151 and a second connecting end face 152 which are parallel to each other, wherein the first connecting end face 151 is adaptively connected to the end face of the flexible hinge 11, and the second connecting end face 152 is adaptively connected to the end face of the first mass block 13, and the area of ​​the second connecting end face 152 is larger than that of the first connecting end face 151, which can increase the sensitivity of the sensor.

[0040] It should be noted that the difference between this embodiment and the cylindrical mass block and the truncated cone transition block is that the trapezoidal transition block can be well combined with the biaxial flexible hinge characteristics, reflecting the efficient dynamic characteristics of the y-axis and z-axis, and the mass block connected to the cantilever beam forms a three-component vibration sensor. However, the use of a cylindrical mass block and a truncated cone transition block will form multi-axis dynamic characteristics, which is inconsistent with the three-component vibration sensor of the present invention.

[0041] It should be noted that the entire structure of the polymer block 1 is symmetrical about the xoy reference plane and the yoz reference plane respectively. There are two reasons. One is to facilitate the installation of FBG, and the other is to maintain the strict consistency of the vibration mode of the sensor in the x, y, and z directions with the directions of the x-axis, y-axis, and z-axis.

[0042] It should be noted that, from the yoz plane, the width of the first mass block 13 in the z direction is greater than the width of the rectangular base 10 in the z direction, which is convenient for installing the FBG and avoiding interference caused by the edge of the base when sensing signals in the y and z directions. It is worth mentioning that if the above conditions are not met, the third FBG 23 cannot be installed normally due to the influence of the rectangular base 10. Normal installation here means that the FBG cannot maintain a vertical tensile state and will be affected by the rectangular base 10 during vibration. Specifically explained as follows: When the FBG is installed on the accelerometer, a certain prestress is applied to maintain the tensile state of the FBG. When the accelerometer senses vibration signals, the FBG can be regarded as a small vibration. Therefore, the width of the first mass block 13 in the z direction is greater than the width of the rectangular base 10 in the z direction, that is, a few millimeters of thickness are reserved so that the FBG will not touch the base 10 during vibration, thereby ensuring that when sensing signals in the y and z directions, there will be no additional force caused by touching the edge of the base.

[0043] It should be noted that the height of the first mass block 13 is consistent with the height of the geometric center of the through hole 101 , and the center of the through hole 101 is located on the y-axis. The FBG passes through the through hole 101 and is connected to the surface of the first mass block 13 respectively.

[0044] It should be noted that the surface of the second mass block 14 on which the FBG is mounted and the x-axial plane of the rectangular base 10 are located in the same plane.

[0045] It should be noted that the flexible hinge 11 is a co-orthogonal composite notch type flexible hinge, and the four sides are overall an asymmetric arc notch structure. Specifically, the notch of the flexible hinge is cut with an arc, and the thickness and notch radius of the thinnest part of the flexible hinge in the y and z directions are different, making the structure asymmetric. The flexible hinge 11 has many advantages such as no gap, no lubrication, no mechanical friction, high sensitivity, high energy conversion rate and high displacement resolution. Different from the cylindrical flexible hinge, the flexible hinge of the present invention is a co-orthogonal composite notch type flexible hinge. This structure forms a biaxial flexible hinge, while the cylindrical flexible hinge will form a multi-axis flexible hinge, which is inconsistent with the design goal.

[0046] From another aspect, the flexible hinge 11 is a co-orthogonal composite notch type flexible hinge, which is a circular arc cut biaxial flexible hinge. In order to match the three-component sensing characteristics involved in the present invention, a biaxial flexible hinge is used in the y and z directions. This structure is different from the cylindrical multi-axis flexible hinge, and can well identify the vibration magnitude of the object to be measured in the y and z directions. At the same time, the flexible hinge 11 is a co-orthogonal composite notch type flexible hinge, which is an asymmetric circular arc cut type flexible hinge. This asymmetry is mainly reflected in the difference in the thickness of the thinnest part of the flexible hinge in the y and z directions and the radius of the circular arc cut. The difference in the thickness of the flexible hinge in two directions directly affects the limit of the sensor's tolerable strength in the y and z directions. Through the design of different thicknesses, it is possible to achieve measurement in vibration environments of different intensities. The radius of the circular arc cut of the flexible hinge in the y and z directions is also an important parameter that directly affects the sensitivity and natural frequency of the sensor in the y and z directions. The appropriate radius size can be used to adapt to vibration measurement environments of different vibration intensities and different frequency ranges.

[0047] It should be noted that the FBG includes: A first FBG 21, wherein the first FBG 21 pigtail is mounted on the rectangular base 10 and the second mass block 14, respectively, and the first FBG 21 is consistent with the y-axis direction; A second FBG 22, wherein the second FBG 22 passes through the through hole 101 and is connected to the surface of the first mass block 13 respectively, and the second FBG 22 is consistent with the x-axis direction; The third FBG 23, the third FBG 23 pigtails are respectively connected to the surface of the first mass block 13, and the third FBG 23 is consistent with the x-axis direction.

[0048] It should be noted that the cantilever beam 12 adopts a long and thin cantilever beam. The surface of the second mass block 14 on which the first FBG21 is installed is located in the same plane as the x-axis plane of the rectangular base 10. This is to ensure that the first FBG21 after installation is parallel to the yoz plane and perpendicular to the x-axis, so that the vibration information in the x-direction can be well sensed. Since the flexible hinge requires a larger mass block to exert its advantages, if a flexible hinge is used here to attach a large mass block structure, it will inevitably cause the first FBG21 to be not parallel to the yoz plane or the overall volume is too large; and because the sensitivity of the short and thick cantilever beam structure is low, in order to combine the above two points, a compromise long and thin cantilever beam structure is selected, which not only ensures a higher sensitivity, but also avoids the problem of excessive volume.

[0049] It should be noted that the through hole 101 is opened on the x-axial surface close to the cantilever beam 12 side.

[0050] According to the three-component FBG vibration sensor of the embodiment of the present invention, the mass block is formed based on polymer integral molding, which has the advantages of low mass, no assembly error, high temperature resistance, strong magnetic resistance, corrosion resistance, etc. It is not only suitable for vibration monitoring in harsh environments, but also can achieve high sensitivity and high natural frequency sensing characteristics under limited volume conditions. Specifically, the sensor of the present invention uses a low mass density polymer block with the characteristics of low mass and small volume, but the sensitivity and natural frequency still reach a high level. The present invention uses a polymer as a mass block to make the FBG three-component vibration sensor a fully non-metallic material, which is more suitable for vibration testing in harsh environments such as strong magnetic fields, acid and alkali, and humidity. The present invention uses a polymer mass block through reasonable structural design, and the mass block and the sensing structure are integrally molded, which effectively avoids errors caused by assembly and improves the stability of sensor performance. Finally, by optimizing the design of the mass block and the sensor structure, a three-component sensor with high sensitivity and high natural frequency is realized.

[0051] This embodiment provides the design steps of the flexible hinge, including the following contents: The geometric structure of the flexible hinge 11 is as follows: Figure 4 As shown, the flexible hinge 11 is a co-orthogonal composite notch type flexible hinge, and its structural feature is an asymmetric arc notch type flexible hinge, and its two side-view rectangular end faces are respectively connected to the x-axial surface of the rectangular base 10 and the smaller rectangular surface of the trapezoidal stage transition block 15, and the flexible hinge 11 can be obtained by cutting a cuboid through a cylinder; Step 1: Set the radius to r z The central axis of the cylinder is parallel to the y-axis, and the interception is moved inward along the z-axis direction of the cuboid until the arc surface of the cylinder intersects the two vertices of the xoz plane of the cuboid. After both sides are intercepted, the top view is as follows Figure 5 As shown in (a) in .

[0052] Step 2: Set the radius to r y The central axis of the cylinder is parallel to the z-axis, and the interception is moved inward along the y-axis direction of the cuboid until the arc surface of the cylinder intersects the two vertices of the xoy plane of the cuboid. After both sides are intercepted, the front view is as follows Figure 5 As shown in (b) in the figure, the structure of the flexible hinge can be obtained.

[0053] In order to provide a sufficient theoretical basis for the research and design of the three-component FBG vibration sensor, this embodiment discloses the theoretical analysis results in the x, y, and z directions. The fixed frequencies and sensitivities in each direction of this embodiment are as follows: The natural frequency of the entire system in the x direction and sensitivity They are: (4) (5) in, It is the initial strain generated by the first FBG 21 when the cantilever beam is initially stationary and is affected by gravity or the pre-tension force of the optical fiber. is the stiffness of the optical fiber of the first FBG 21, is the stiffness of the cantilever beam. is the equivalent mass of the cantilever beam and the second mass block. is the effective elastic-optical coefficient of the optical fiber, is the effective length of the optical fiber of the first FBG 21 in the x direction, is the length of the first connecting surface 151 and the second connecting surface 152 in the x direction.

[0054] Natural frequency in the y direction , Sensitivity formula: (6) (7) In the formula, is the stiffness of the biaxial flexible hinge rotating in the y direction. is the stiffness of the second FBG fiber. Figure 3 As shown, is the length of the first mass block in the y direction, and the effective length of the optical fiber of the second FBG22 and the third FBG23 is , is the distance from the center of the flexible hinge to the center of mass of the mass block, is the equivalent mass of the flexible hinge and the first mass block.

[0055] The same method can be used to obtain the natural frequency of the entire system in the z direction: and sensitivity They are: (8) (9) in, is the stiffness of the biaxial flexure hinge rotating in the z direction, is the stiffness of the optical fiber of the third FBG 23, is the width of the first mass block in the z direction.

[0056] This embodiment provides the following specific implementation cases: The integrated polymer material block is formed by methacrylic monomer, photoinitiator and additives after being photocured by a 3D printer at 405nm for 10 minutes. The elastic modulus is 2.29737GPa, the density is 1359.6kg / m3, and the Poisson's ratio is 0.35.

[0057] A three-dimensional coordinate system is established with the geometric center of the rectangular base, where the dimensions of each component are as follows: 1. The length of the rectangular base 10 in the x direction is 11 mm, the length in the y direction is 30 mm, and the length in the z direction is 18 mm; 2. The second mass block 14 has a length of 11 mm in the x direction, a length of 9 mm in the y direction, and a length of 18 mm in the z direction; 3. The cantilever beam 12 has a length of 1.9 mm in the x direction, 25 mm in the y direction, and 18 mm in the z direction; 4. The length of the first mass block 13 in the x direction is 13.5 mm, the length in the y direction is 18 mm, and the length in the z direction is 27 mm; 5. The thickness of the flexible hinge 11 at its thinnest point in the y direction is t y =2.69mm, the thinnest thickness in the z direction is t z =4.87mm; the radii of the cutting circles are r y =7.5mm, r z =4.4mm; the central axis of the flexible hinge 11 along the x direction coincides with the central axis of the base along the x direction; 6. The length of the flexible hinge 11 in the x direction is 8 mm, the length in the y direction is 5 mm, and the length in the z direction is 10 mm; 7. The geometric dimensions of the entire device are 70mm×27mm×64mm, and the FBG length is less than 1cm.

[0058] The performance of the three-dimensional FBG vibration sensor of this embodiment is compared with that of the existing three-dimensional FBG acceleration vibration sensor, and the following test statistical data are obtained, as shown in Table 1: Table 1: Performance comparison of three-dimensional FBG acceleration vibration sensors The analysis with Comparative Example 1 is as follows: ① The sensor of comparative example 1 is assembled with fastening bolts. The sensor is assembled with multiple tiny parts and fastening bolts, and the assembly is extremely complicated. The sensor is prone to nonlinear vibration caused by loosening of fastening bolts under long-term vibration, and the resonance characteristics undergo nonlinear changes. For example, due to the nonlinear effect, the actual natural frequency is less than the designed natural frequency, which is a fraction of the original natural frequency, thereby greatly reducing the operating frequency of the sensor.

[0059] The present invention is made of polymer material using an integrated molding technology, and there is no problem of fastener loosening.

[0060] ② In comparative example 1, the sensor is made of metal material. Since metal material has the characteristic of high density, it weakens the advantage of optical fiber sensor as a non-metallic material sensor in terms of light weight. When measuring vibration, it is easy to have measurement errors due to its own weight.

[0061] The polymer material used in the present invention has the advantages of corrosion resistance, moisture resistance, and strong magnetic interference resistance, which better matches the characteristics of optical fiber sensors in terms of corrosion resistance, moisture resistance, and strong magnetic interference resistance. In addition, since the polymer has the characteristics of low density, the weight of the present invention is relatively light and it is not easy to produce measurement errors caused by weight.

[0062] The analysis with Comparative Example 2 is as follows: ① The sensor of comparative example 2 is assembled with fastening bolts. The sensor is assembled with multiple tiny parts and fastening bolts, which is extremely complicated to assemble. The sensor is prone to nonlinear vibration caused by loosening of fastening bolts under long-term vibration, and the resonance characteristics undergo nonlinear changes. For example, due to the nonlinear effect, the actual natural frequency is less than the designed natural frequency, which is a fraction of the original natural frequency, thereby greatly reducing the operating frequency of the sensor.

[0063] The invention is made of polymer material by using an integral molding technology, and there is no problem of loosening of fasteners.

[0064] ② In comparative example 2, the sensor is made of metal material. Since metal material has the characteristic of high density, it weakens the advantage of optical fiber sensor as a non-metallic material sensor in terms of light weight. When measuring vibration, it is easy to have measurement errors due to its own weight.

[0065] The polymer material used in the present invention has the advantages of corrosion resistance, moisture resistance, and strong magnetic interference resistance, which better matches the characteristics of optical fiber sensors in terms of corrosion resistance, moisture resistance, and strong magnetic interference resistance. In addition, since the polymer has the characteristics of low density, the weight of the present invention is relatively light and it is not easy to produce measurement errors caused by weight.

[0066] ③ The hinge of the sensor in Example 2 is too weak, which is prone to fatigue fracture, and the processing accuracy of the vibration pickup structure is difficult to guarantee.

[0067] The present invention performs strength analysis on the accelerometer, and can perform normal measurements within the test range without such a problem.

[0068] The analysis with Comparative Example 3 is as follows: ① The sensor of comparative example 3 is assembled with fastening bolts. The sensor is assembled with multiple tiny parts and fastening bolts, which is extremely complicated. The sensor is prone to nonlinear vibration caused by loosening of fastening bolts under long-term vibration, and the resonance characteristics undergo nonlinear changes. For example, due to the nonlinear effect, the actual natural frequency is less than the designed natural frequency, which is a fraction of the original natural frequency, thereby greatly reducing the operating frequency of the sensor.

[0069] The invention is made of polymer material by using an integral molding technology, and there is no problem of loosening of fasteners.

[0070] ② The sensor of Example 3 is made of metal material. Since metal material has the characteristic of high density, it weakens the advantage of optical fiber sensor as a non-metallic material sensor in terms of light weight. When measuring vibration, it is easy to have measurement errors due to its own weight.

[0071] The polymer material used in the present invention has the advantages of corrosion resistance, moisture resistance, and strong magnetic interference resistance, which better matches the characteristics of optical fiber sensors in terms of corrosion resistance, moisture resistance, and strong magnetic interference resistance. In addition, since the polymer has the characteristics of low density, the weight of the present invention is relatively light and it is not easy to produce measurement errors caused by weight.

[0072] The analysis with Comparative Example 4 is as follows: ① The sensor of comparative example 4 is assembled with fastening bolts. The sensor is assembled with multiple tiny parts and fastening bolts, and the assembly is extremely complicated. The sensor is prone to nonlinear vibration caused by loosening of fastening bolts under long-term vibration, and the resonance characteristics undergo nonlinear changes. For example, due to the nonlinear effect, the actual natural frequency is less than the designed natural frequency, which is a fraction of the original natural frequency, thereby greatly reducing the operating frequency of the sensor.

[0073] The invention is made of polymer material by using an integral molding technology, and there is no problem of loosening of fasteners.

[0074] ② Comparative Example 4 uses 5 FBGs. Too many FBGs cause the sensor to be more easily damaged. The present invention uses only 3 FBGs.

[0075] ③ The sensitivity of the sensor of Example 4 in three directions is 9.7 / 10.13 / 7.45 pm / g respectively. The sensitivity is too low to be convenient for testing the scene of tiny vibration.

[0076] The sensitivities of the sensor of the present invention in three directions are 57.03 / 128.16 / 60.49 pm / g respectively, which can better measure the scene of tiny vibrations.

[0077] ④ The sensor of Example 4 is made of metal material. Since metal material has the characteristic of high density, it weakens the advantage of optical fiber sensor as a non-metallic material sensor in terms of light weight. When measuring vibration, it is easy to have measurement errors due to its own weight.

[0078] The polymer material used in the present invention has the advantages of corrosion resistance, moisture resistance, and strong magnetic interference resistance, which better matches the characteristics of optical fiber sensors in terms of corrosion resistance, moisture resistance, and strong magnetic interference resistance. In addition, since the polymer has the characteristics of low density, the weight of the present invention is relatively light and it is not easy to produce measurement errors caused by weight.

[0079] The analysis with Comparative Example 5 is as follows: ① The sensor of comparative example 5 is assembled with fastening bolts. The sensor is assembled with multiple tiny parts and fastening bolts, and the assembly is extremely complicated. The sensor is prone to nonlinear vibration caused by loosening of fastening bolts under long-term vibration, and the resonance characteristics undergo nonlinear changes. For example, due to the nonlinear effect, the actual natural frequency is less than the designed natural frequency, which is a fraction of the original natural frequency, thereby greatly reducing the operating frequency of the sensor.

[0080] The invention is made of polymer material by using an integral molding technology, and there is no problem of loosening of fasteners.

[0081] ② The sensor of Example 5 is made of metal material. Since metal material has the characteristic of high density, it weakens the advantage of optical fiber sensor as a non-metallic material sensor in terms of light weight. When measuring vibration, it is easy to have measurement errors due to its own weight.

[0082] The polymer material used in the present invention has the advantages of corrosion resistance, moisture resistance, and strong magnetic interference resistance, which better matches the characteristics of optical fiber sensors in terms of corrosion resistance, moisture resistance, and strong magnetic interference resistance. In addition, since the polymer has the characteristics of low density, the weight of the present invention is relatively light and it is not easy to produce measurement errors caused by weight.

[0083] ③ Comparative Example 5 uses 6 FBGs. Too many FBGs will cause the problem of being more easily damaged. The present invention only has 3 FBGs, which has better safety.

[0084] The analysis of Comparative Example 6 is as follows: ① The sensor of comparative example 6 is assembled with fastening bolts. The sensor is assembled with multiple tiny parts and fastening bolts, and the assembly is extremely complicated. The sensor is prone to nonlinear vibration caused by loosening of fastening bolts under long-term vibration, and the resonance characteristics undergo nonlinear changes. For example, due to the nonlinear effect, the actual natural frequency is less than the designed natural frequency, which is a fraction of the original natural frequency, thereby greatly reducing the operating frequency of the sensor.

[0085] The invention is made of polymer material by using an integral molding technology, and there is no problem of loosening of fasteners.

[0086] ② The sensor of Example 6 is made of metal material. Since metal material has the characteristic of high density, it weakens the advantage of optical fiber sensor as a non-metallic material sensor in terms of light weight. When measuring vibration, it is easy to have measurement errors due to its own weight.

[0087] The polymer material used in the present invention has the advantages of corrosion resistance, moisture resistance, and strong magnetic interference resistance, which better matches the characteristics of optical fiber sensors in terms of corrosion resistance, moisture resistance, and strong magnetic interference resistance. In addition, since the polymer has the characteristics of low density, the weight of the present invention is relatively light and it is not easy to produce measurement errors caused by weight.

[0088] ③ Comparative Example 6 uses 6 FBGs. Too many FBGs will cause the sensor to be more easily damaged. The maximum detectable acceleration is 3g, which is not suitable for testing high-intensity vibration.

[0089] The present invention has only three FBGs, and the accelerometer is subjected to strength analysis. The accelerometer can withstand acceleration of 10g in three test directions without being damaged, and has better safety in comparison.

[0090] The analysis of Comparative Example 7 is as follows: ① The sensor of comparative example 7 is assembled with fastening bolts. The sensor is assembled with multiple tiny parts and fastening bolts, and the assembly is extremely complicated. The sensor is prone to nonlinear vibration caused by loosening of fastening bolts under long-term vibration, and the resonance characteristics undergo nonlinear changes. For example, due to the nonlinear effect, the actual natural frequency is less than the designed natural frequency, which is a fraction of the original natural frequency, thereby greatly reducing the operating frequency of the sensor.

[0091] The invention is made of polymer material by using an integral molding technology, and there is no problem of loosening of fasteners.

[0092] ② In comparative example 1, the sensor is made of metal material. Since metal material has high density, it weakens the advantage of optical fiber sensor as a non-metallic material sensor in terms of light weight. When measuring vibration, it is easy to have measurement errors due to its own weight.

[0093] The polymer material used in the present invention has the advantages of corrosion resistance, moisture resistance, and strong magnetic interference resistance, which better matches the characteristics of optical fiber sensors in terms of corrosion resistance, moisture resistance, and strong magnetic interference resistance. In addition, since the polymer has the characteristics of low density, the weight of the present invention is relatively light and it is not easy to produce measurement errors caused by weight.

[0094] After comprehensive analysis, the differences between the present invention and the prior art are mainly divided into the following points: The three-component acceleration vibration sensor of the present invention adopts co-positioned orthogonal composite notch-type flexible hinges on both sides of the rectangular base, which is an asymmetric arc-cut structure, which is different from the cylindrical flexible hinge structure with a thin middle and thick ends. The mass blocks connected to both sides of the biaxial arc-cut flexible hinge by the trapezoidal transition block are rectangular parallelepiped structures, which are different from the cylindrical structures. This structure enables the flexible hinge to better capture vibrations from the y and z directions; while the cylindrical flexible hinge structure is sensitive to multi-axis vibrations, and therefore cannot meet the requirements of three-component vibration sensing. The three-component acceleration vibration sensor of the present invention adopts a long cantilever beam structure for sensing the vibration in the x direction. The characteristic of this structure is different from that of the flexible hinge. The structure with the flexible hinge as the elastic body usually needs to be connected to a larger mass block to reflect its advantages. Since the installation method of the FBG measuring the x direction must be kept orthogonal to the x-axis, it is not advisable to set the second mass block on the top too large, otherwise it will inevitably cause the volume of the rectangular base to be too large, making it difficult to control the volume of the sensor; and since the short and thick cantilever beam structure can greatly reduce the volume of the sensor, it will sacrifice too much sensitivity in the x direction. Therefore, a compromise long and thin cantilever beam structure is adopted to ensure that the x direction achieves greater sensitivity and less cross interference while taking into account the volume design of the sensor. At present, the design of the FBG acceleration vibration sensor recorded in the prior art basically adopts metal materials, which has the problem of assembly trouble caused by too many accessories, and the problem of loose interference between the fastening bolts and various components. The present invention adopts polymer materials and is obtained by 3D printing technology, which is convenient for the integrated design of the sensor structure and greatly reduces the influence of parts assembly on performance. Different from most sensors currently made of high-density metal materials, such as manganese 65, tantalum, stainless steel, etc. The performance of metal mass blocks will be affected in harsh environments such as strong magnetism, humidity, acid and alkali, and their use itself weakens the advantages of optical fiber sensors as non-metallic material sensors that are suitable for harsh environments and light weight. The polymer material used in the present invention has the advantages of corrosion resistance, moisture resistance, and resistance to strong magnetic interference, which better matches the characteristics of optical fiber sensors that are resistant to corrosion, moisture resistance, and strong magnetic interference. Therefore, sensors made of this material are suitable for vibration monitoring in more severe environments. Sensors made of non-metallic composite materials in the prior art are all one-dimensional sensors and are not suitable for vibration environments that require all-round monitoring. The three-component acceleration sensor described in the present invention can perform all-round measurements in harsh environments; the three-component FBG vibration sensor of the present invention is compared with the current existing three-dimensional acceleration FBG vibration sensor. The present invention takes advantage of polymer materials, not only can it accurately measure vibration signals in three dimensions in more severe environments, but also can achieve the natural frequency and sensitivity in the three directions of x, y, and z that are comparable to the performance of steel materials, while achieving lower cross-interference sensitivity. Example 2 According to a second aspect of an embodiment of the present invention, a method for using a three-component FBG vibration sensor is provided, wherein the three-component FBG vibration sensor is used to measure an object to be measured, comprising the following steps: Step S100, the sensitivity of the packaged three-component FBG vibration sensor in the x, y, and z directions is tested to obtain the relationship between the central wavelength offset of the FBG in the x, y, and z directions and the acceleration in each direction, and then obtain the sensitivity matrix. The relationship between the acceleration of the sensor in the x, y, and z directions and the change in the central wavelength of the FBG is as follows: , in, They are respectively represented as the central wavelength changes of the first FBG, the second FBG, and the third FBG, Respectively represent the acceleration applied in the x, y, and z directions; is the sensitivity matrix, where: It is expressed as the sensitivity of the sensor in the x direction when the x-direction vibration is applied. It represents the cross-coupling interference sensitivity in the y direction when the acceleration in the x direction is applied. It represents the cross-coupling interference sensitivity in the z direction when the acceleration in the x direction is applied; It is expressed as the cross-coupling interference sensitivity of the sensor in the x direction when vibration in the y direction is applied. It indicates the sensitivity felt in the y direction when the y direction acceleration is applied. It represents the cross-coupling interference sensitivity in the z direction when the acceleration in the x direction is applied; It is expressed as the cross-coupling interference sensitivity of the sensor in the x direction when vibration in the z direction is applied. It represents the cross-coupling interference sensitivity in the y direction when the z-direction acceleration is applied. It indicates the sensitivity felt in the z direction when the z-direction acceleration is applied; Step S200, fixing the surface of the rectangular base (10) away from the cantilever beam (12) on the surface of the object to be measured; Step S300: When the object under test is vibrated, the central wavelength offsets of the three FBGs are collected. , , ; Step S400, the sensitivity matrix of the sensor is measured according to step S100, which is given by the following relationship: The acceleration in each direction can be obtained, where is the inverse matrix of the sensitivity matrix.

[0095] It should be noted that this embodiment also provides a test method for the relationship between the vibration amplitude of the sensor in the x, y, and z directions and the change in the central wavelength of the FBG based on step S100. Specifically, when the vibration direction is parallel to the x direction, the change in the central wavelength of the FBG of the sensor in the x, y, and z directions can be measured to obtain the response of the sensor in the x direction. , and the cross-coupling interference response in the y and z directions , (All are normalized sensitivities). When the vibration direction is parallel to the y direction, the change in the central wavelength of the FBG of the sensor in the x, y, and z directions can be measured to obtain the response of the sensor in the y direction. , and the cross-coupling interference response in the x and z directions , (All are normalized sensitivities). When the vibration direction is parallel to the z direction, the change in the central wavelength of the FBG of the sensor in the x, y, and z directions can be measured to obtain the response of the sensor in the z direction. , and the cross-coupling interference response in the x and y directions , (All are normalized sensitivities). The sensitivity coefficient obtained by the test , , , , , , , , Substituting the relationship between the vibration amplitude of the sensor in the x, y, and z directions and the change in the central wavelength of the FBG in step S100, the specific parameters in this embodiment are: It should be noted that, according to the relationship between the vibration amplitude of the sensor in each direction and the change in the central wavelength of the FBG measured in step S100, the relationship in step S100 can be transformed into the decoupling relationship of the acceleration sensor as shown below: The decoupling relationship of the acceleration sensor in this embodiment is specifically expressed as: It should be noted that, according to the relationship between the acceleration of the sensor in the x, y, and z directions measured in step S100 and the change in the central wavelength of the FBG, the decoupling relationship of the acceleration sensor mentioned in step S400 can be obtained, so that the vibration of the object under test can be measured according to the decoupling relationship of the sensor.

[0096] It should be noted that the test method for the relationship between the vibration amplitude of the three-component acceleration sensor in the x, y, and z directions and the change in the central wavelength of the FBG in step S100 is to test the response in the x direction when the vibration direction is parallel to the x direction, and the cross-coupling interference response in the y and z directions, and normalize the sensitivity in the y and z directions with the sensitivity in the x direction of the main axis as 1, so as to obtain the sensitivity matrix , , The same method can be used to obtain the remaining coefficients in the relationship between the sensor's vibration amplitude in the x, y, and z directions and the change in the FBG's central wavelength. , , , , , .

[0097] It should be noted that, for ease of understanding, the following supplementary explanation is made: In this embodiment, the acceleration sensitivity of the sensor in the x, y, and z directions is 57.03pm / g, 128.16pm / g, and 60.49pm / g respectively. For the embodiment, the specific explanation of each parameter of the decoupling relation of the acceleration sensor is that, assuming that the sensor is only subjected to vibration in the x direction, the y and z directions are , No response, then according to the sensitivity in the x direction You can get , thus obtaining the acceleration in the x direction. If the sensor receives a vibration signal from an unknown direction in three-dimensional space, then the sensor will be , , The change in the central wavelength, at this time, the responses in the x, y, and z directions are waveforms containing coupled cross-interference. If you want to get the real acceleration vibration signal input, you need to decouple it again according to the sensitivity decoupling relationship described in this embodiment.

[0098] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the invention.

[0099] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0100] Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Mentioning "embodiment" in this article means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present embodiment application. The appearance of this phrase in various positions in the specification is not necessarily the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It can be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0101] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A three-component FBG vibration sensor, comprising FBG, characterized in that: Also includes: An integrally formed polymer block (1), the polymer block (1) comprising: A rectangular base (10), wherein a three-dimensional coordinate system is constructed with the geometric center of the rectangular base (10) as the origin, the rectangular base (10) having an x-axial surface, a y-axial surface and a z-axial surface, and a through hole (101) is provided on the x-axial surface; Two flexible hinges (11), respectively connected to the x-axis plane and symmetrical about the yoz reference plane, have two rotational degrees of freedom, one for measuring the acceleration in the y direction, the movement mode is rotation around the z axis, and the other for measuring the acceleration in the z direction, the movement mode is rotation around the y axis; Two first mass blocks (13) are respectively connected to the end faces of the flexible hinge (11), and pigtails of FBGs parallel to the x-axis are connected to the surfaces of the first mass blocks (13) to form a y-direction vibration detection module and a z-direction vibration detection module; A cantilever beam (12) connected to any y-axial surface; The second mass block (14) is connected to the end face of the cantilever beam (12), and the pigtail of the FBG parallel to the y-axis is connected to the surface of the second mass block (14) and the x-axial surface of the rectangular base (10) to form an x-direction vibration detection module.

2. The three-component FBG vibration sensor according to claim 1, characterized in that: The polymer block (1) further comprises: Two trapezoidal stage transition blocks (15) have a first connecting end face (151) and a second connecting end face (152) which are parallel to each other, wherein the first connecting end face (151) is adaptively connected to the end face of the flexible hinge (11), and the second connecting end face (152) is adaptively connected to the end face of the first mass block (13), and the area of ​​the second connecting end face (152) is greater than the area of ​​the first connecting end face (151).

3. The three-component FBG vibration sensor according to claim 2, characterized in that: The entire structure of the polymer block (1) is symmetrical about the xoy reference plane and the yoz reference plane.

4. The three-component FBG vibration sensor according to claim 1, characterized in that: Viewed from the yoz plane, the width of the first mass block (13) in the z direction is greater than the width of the rectangular base (10) in the z direction.

5. The three-component FBG vibration sensor according to claim 1, characterized in that: The height of the first mass block (13) is consistent with the height of the geometric center of the through hole (101), and the geometric center of the through hole (101) is located on the y-axis, and the FBG passes through the through hole (101) and is respectively connected to the surface of the first mass block (13).

6. The three-component FBG vibration sensor according to claim 1, characterized in that: The surface of the second mass block (14) on which the FBG is mounted is located in the same plane as the x-axial plane of the rectangular base (10).

7. The three-component FBG vibration sensor according to claim 1, characterized in that: The flexible hinge (11) is a co-located orthogonal composite notch-type flexible hinge, and the four sides are overall an asymmetric arc-cut structure. Specifically, the notch of the flexible hinge is cut using an arc, and the thickness and notch radius of the thinnest part of the flexible hinge in the y and z directions are different, so that the structure is asymmetric.

8. The three-component FBG vibration sensor according to claim 1, characterized in that: The FBG comprises: A first FBG (21), wherein a pigtail of the first FBG (21) is mounted on a rectangular base (10) and a second mass block (14) respectively, and an axial direction of the first FBG (21) is consistent with a y-axis direction; a second FBG (22), the second FBG (22) passing through the through hole (101) and connected to the surface of the first mass block (13), the axial direction of the second FBG (22) being consistent with the x-axis direction; A third FBG (23), wherein the third FBG (23) tail fibers are respectively connected to the surface of the first mass block (13), and the axial direction of the third FBG (23) is consistent with the x-axis direction.

9. The three-component FBG vibration sensor according to claim 1, characterized in that: The through hole (101) is opened on the x-axial surface close to the cantilever beam (12) side.

10. A method for using a three-component FBG vibration sensor, characterized in that: Measuring an object to be measured using the three-component FBG vibration sensor as claimed in any one of claims 1 to 9 comprises the following steps: Step S100, the sensitivity of the packaged three-component FBG vibration sensor in the x, y, and z directions is tested to obtain the relationship between the central wavelength offset of the FBG in the x, y, and z directions and the acceleration in each direction, and then obtain the sensitivity matrix. The relationship between the acceleration of the sensor in the x, y, and z directions and the change in the central wavelength of the FBG is as follows: ， in, They are respectively represented as the central wavelength changes of the first FBG, the second FBG, and the third FBG, Respectively represent the acceleration applied in the x, y, and z directions; is the sensitivity matrix, where: It is expressed as the sensitivity of the sensor in the x direction when the x-direction vibration is applied. It represents the cross-coupling interference sensitivity in the y direction when the acceleration in the x direction is applied. It represents the cross-coupling interference sensitivity in the z direction when the acceleration in the x direction is applied; It is expressed as the cross-coupling interference sensitivity of the sensor in the x direction when vibration in the y direction is applied. It indicates the sensitivity felt in the y direction when the y direction acceleration is applied. It represents the cross-coupling interference sensitivity in the z direction when the acceleration in the x direction is applied; It is expressed as the cross-coupling interference sensitivity of the sensor in the x direction when vibration in the z direction is applied. It represents the cross-coupling interference sensitivity in the y direction when the z-direction acceleration is applied. It indicates the sensitivity felt in the z direction when the z-direction acceleration is applied; Step S200, fixing the surface of the rectangular base (10) away from the cantilever beam (12) on the surface of the object to be measured; Step S300: When the object under test is vibrated, the central wavelength offsets of the three FBGs are collected. , , ; Step S400, the sensitivity matrix of the sensor is measured according to step S100, which is given by the following relationship: ， The acceleration in each direction can be obtained, where is the inverse matrix of the sensitivity matrix.

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