Three-dimensional fiber Bragg grating displacement sensor with spiral elastic beam structure

Abstract

The invention discloses a three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure, the grating displacement sensor is composed of an optical fiber with an optical fiber sensor and three displacement bodies, the three displacement bodies have the same structure and are arranged in a pairwise orthogonal manner, and the displacement bodies are connected through a base. The displacement body is composed of a measuring rod, a first bearing part, a second bearing part, a third bearing part, a first spring and a spiral elastic beam, the measuring rod is in threaded connection with the first bearing part, the first bearing part is connected with the second bearing part through the first spring, the second bearing part is in threaded connection with the third bearing part, and the spiral elastic beam is connected with the measuring rod. The third bearing part is fixedly connected with the bottom through a spiral elastic beam, and the part, provided with the optical fiber sensor, of the optical fiber is pasted to the spiral elastic beam and used for detecting tiny deformation and temperature change of the spiral elastic beam.

Description

Technical Field

[0001] The invention relates to the technical field of sensors, and in particular to a three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure. Background Art

[0002] Displacement is a physical quantity with both direction and magnitude. It is a directed line segment used to represent the position of a particle and is also one of the most basic quantities in measurement technology. Therefore, displacement measurement occupies a very important position in power systems, aerospace, structural health monitoring, robotics, automation control, and metal structure strain. For displacement detection, it has experienced a transition from the classical displacement sensor stage before the 1980s to the semiconductor displacement sensor stage after the 1980s. The corresponding displacement sensors also have higher sensitivity, higher accuracy, good repeatability and cost-effectiveness. Traditional displacement sensors include inductive, photoelectric, capacitive, etc., which have played an important role in many occasions. However, these traditional sensors are often interfered by environmental factors and are easily affected by external factors such as electromagnetic interference and temperature changes, resulting in reduced measurement accuracy, unstable signals or equipment damage.

[0003] Fiber Bragg Grating (FBG) is a diffraction grating, which is formed by periodically modulating the refractive index of the fiber core along the axial direction by a certain method. It is a passive device. Fiber Bragg Grating has the characteristics of low insertion loss, low cost, strong anti-electromagnetic interference ability, high wavelength selectivity, compatibility with optical fiber system, good corrosion resistance, etc. FBG sensor is based on the principle of periodic refractive index change in optical fiber. When external stress, temperature or displacement is applied, the central wavelength of the fiber Bragg grating reflection changes. By detecting this wavelength change, it is possible to measure external displacement, deformation and other physical quantities.

[0004] The basic principle of FBG displacement sensor is that when the fiber Bragg grating is under the action of external force, the length of the fiber changes slightly, causing the reflection wavelength of the fiber Bragg grating to shift. By detecting the change in wavelength, the magnitude of the external force can be inferred. Due to the high sensitivity, low loss and good signal quality of optical fiber during long-distance transmission, FBG displacement sensors have been used in many fields, especially in harsh environments that traditional electrical sensors cannot adapt to, such as high temperature, high pressure, electromagnetic interference, etc.

[0005] However, existing fiber Bragg grating displacement sensors have some technical limitations, especially in the application of multi-dimensional displacement measurement, and still face some challenges and shortcomings.

[0006] Problems and shortcomings of current technology:

[0007] 1. Limitations of single-dimensional measurement

[0008] Traditional fiber Bragg grating displacement sensors can usually only be used for single-dimensional (usually axial) displacement measurement. Although two-dimensional or three-dimensional displacement measurement can be achieved by combining multiple sensors, this method requires more fiber Bragg grating elements, which increases the complexity and cost of the system. The existing technology has not yet well realized the integration and simplified design of fiber Bragg grating displacement sensors in multi-dimensional (such as X, Y, and Z axis) displacement measurement. For some complex application scenarios, such as structural health monitoring, robot precise positioning and other fields, the demand for multi-dimensional displacement measurement is particularly urgent.

[0009] The reflection wavelength of the fiber Bragg grating is not only related to the external force or displacement, but also closely related to factors such as the ambient temperature and the strain of the optical fiber itself. When traditional FBG sensors measure displacement, temperature changes often cause wavelength drift, resulting in measurement errors. This problem is particularly evident in environments where temperature and external force changes are more drastic. Therefore, in practical applications, a corresponding compensation mechanism must be designed, which increases the complexity and difficulty of using the sensor.

[0010] 2. Complexity of sensor arrays

[0011] In multi-dimensional displacement measurement, it is usually necessary to arrange multiple FBG sensor arrays to obtain displacement information in different directions. This multi-point arrangement makes the system complicated, and the installation, data acquisition and processing of sensors require additional consideration. In addition, multiple fiber optic sensors may interfere with each other, causing cross-interference of signals, which in turn affects the measurement accuracy and stability. Therefore, how to optimize the design of the sensor array and reduce mutual interference has become a major problem in current technology.

[0012] 3. Insufficient sensitivity and resolution

[0013] Although fiber Bragg grating sensors have high sensitivity, the sensitivity and resolution of existing FBG displacement sensors still cannot meet the requirements in some applications with high precision requirements. For example, for the precise measurement of tiny displacements, the response speed and signal-to-noise ratio of existing sensors may be insufficient, resulting in the inability to provide sufficiently accurate measurement results. Improving the sensitivity and resolution of FBG displacement sensors, especially in high-frequency dynamic measurements, is still an urgent problem to be solved.

[0014] 4. Cost and application popularity

[0015] Although fiber optic sensing technology has many advantages, the high manufacturing and installation costs of fiber Bragg grating sensors have prevented this technology from being popularized in some low-cost, high-volume applications. In addition, the design and manufacturing of FBG sensors require relatively complex technical support, which also limits its application in small and medium-sized enterprises. How to reduce the cost of FBG displacement sensors and increase their market penetration is also a challenge facing current fiber optic sensing technology. Summary of the invention

[0016] In view of the above-mentioned prior art, the present invention provides a three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure, which mainly solves the technical problems existing in the above-mentioned background technology.

[0017] To achieve the above object, the technical solution of the embodiment of the present invention is implemented as follows:

[0018] A three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure, the grating displacement sensor is composed of an optical fiber with an optical fiber sensor and three displacement bodies with the same structure and placed orthogonally to each other, the displacement bodies are connected to each other through a base, the displacement body is composed of a measuring rod, a first bearing part, a second bearing part, a third bearing part, a first spring, and a spiral elastic beam, the measuring rod is threadedly connected to the first bearing part, the first bearing part and the second bearing part are connected through the first spring, the second bearing part and the third bearing part are threadedly connected, the third bearing part is fixedly connected to the bottom through the spiral elastic beam, the part of the optical fiber with the optical fiber sensor is pasted on the spiral elastic beam, and is used to detect small deformation and temperature changes of the spiral elastic beam.

[0019] Preferably, the spiral elastic beam consists of a first fixed part, a second fixed part, and a second spring, wherein the first fixed part and the second fixed part are connected via the second spring, the other end of the first fixed part is fixedly connected to the third bearing part, and the other end of the second fixed part is fixedly connected to the bottom.

[0020] Preferably, the optical fiber sensor includes three FBG optical fiber sensors, one FBG optical fiber sensor is pasted on one side of the second spring, another FBG optical fiber sensor is pasted on the other side of the second spring, and the last FBG optical fiber sensor is located between the other two FBG optical fiber sensors. The two FBG optical fiber sensors pasted on the second spring are used to detect slight deformations of the second spring, and one FBG optical fiber sensor is used to detect external temperature changes at the second spring.

[0021] Preferably, the displacement body housing is composed of a circular slide rail housing and a slide rail housing with a base, and the displacement body is sleeved in the displacement body housing.

[0022] Preferably, the grating displacement sensor further comprises a main body shell, the base is arranged inside the main body shell, and through holes for the displacement body to pass through are provided in three directions of the main body shell.

[0023] Preferably, the optical fiber with the optical fiber sensor passes through the through hole and is connected to the photoelectric converter signal.

[0024] Preferably, the FBG optical fiber sensor is adhered to the second spring by means of an optical fiber adhesive, wherein the optical fiber adhesive comprises epoxy resin.

[0025] Preferably, the change in the central wavelength of the three-dimensional fiber Bragg grating displacement sensor varies linearly with the displacement to be measured, and the displacement change can be measured by the central wavelength, wherein the expression of the central wavelength is:

[0026]

[0027] Among them, λ B is the central wavelength of FBG, K g is the strain sensitivity coefficient of the optical fiber, K1 is the elastic coefficient of the first spring, K2 is the elastic coefficient of the second spring, L is the length of the optical fiber, x is the displacement change, Δλ 1,2 is the change in the central wavelength.

[0028] The beneficial effects of the present invention are: it breaks through the limitation that traditional sensors can only perform single-dimensional measurements, and realizes the comprehensive measurement of three-dimensional displacement; secondly, the spiral elastic beam structure is adopted, which can convert large displacement into smaller deformation and convert it into changes in the central wavelength of the fiber grating, significantly improving the sensitivity of the measurement; at the same time, the temperature compensation technology effectively reduces the influence of temperature fluctuations on the measurement accuracy, and further improves the stability and accuracy of the measurement; in addition, the sensor array design is simplified, and the module and the sensor body adopt a detachable structure, which is convenient to meet the measurement requirements of different dimensions, reducing the complexity of the system and the difficulty of installation. Therefore, the present invention has significant technical advantages in multi-dimensional precise measurement, structural simplification and temperature stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the overall structure of the sensor in the embodiment of the present application;

[0030] Figure 2 This is a schematic diagram of the overall structure of the spiral elastic beam in the embodiment of the present application;

[0031] Figure 3 This is an external schematic diagram of a sensor in an embodiment of the present application;

[0032] Figure 4It is a cross-sectional view of the sensor in the embodiment of the present application.

[0033] Description of Figure Numbers:

[0034] 1. Base; 2. Measuring rod; 3. First bearing part; 4. Second bearing part; 5. Third bearing part; 6. First spring; 7. Spiral elastic beam; 71. First fixing part; 72. Second fixing part; 73. Second spring; 8. Circular slide rail housing; 9. Slide rail housing with base; 10. Main body housing; 11. FBG optical fiber sensor; 12. Connecting rod; 13. Through hole; 14. Displacement body housing. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further elaborated in detail below in conjunction with the drawings and specific embodiments of the specification. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. In the following description, the expression "some embodiments" is related to a subset of all possible embodiments, but it should be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict.

[0036] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0037] It should be understood that the present invention can be implemented in different forms and should not be interpreted as being limited to the embodiments proposed herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and the scope of the present invention will be fully conveyed to those skilled in the art. And the purpose of the terms used herein is only to describe specific embodiments and is not intended to be a limitation of the present invention. When used herein, the singular forms of "one", "one" and "said / the" are also intended to include plural forms, unless the context clearly indicates another way. It should also be understood that the terms "compose" and / or "include" when used in this specification determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0038] It should also 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 a central 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 a central element at the same time. The terms "vertical", "horizontal", "inside", "outside", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0039] In order to fully understand the present invention, a detailed structure will be proposed in the following description to illustrate the technical solution proposed by the present invention. The optional embodiments of the present invention are described in detail as follows, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0040] Please refer to the attached Figures 1 to 4 The present application provides a three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure, wherein the grating displacement sensor is composed of an optical fiber with an optical fiber sensor and three displacement bodies with the same structure and placed orthogonally to each other, wherein the displacement bodies are connected to each other through a base 1, and the displacement body is composed of a measuring rod 2, a first bearing part 3, a second bearing part 4, a third bearing part 5, a first spring 6, and a spiral elastic beam 7, wherein the measuring rod 2 is threadedly connected to the first bearing part 3, the first bearing part 3 is connected to the second bearing part 4 through the first spring 6, the second bearing part 4 is threadedly connected to the third bearing part 5, and the third bearing part 5 is fixedly connected to the bottom through the spiral elastic beam 7, and the part of the optical fiber with the optical fiber sensor is pasted on the spiral elastic beam 7 for detecting small deformation and temperature changes of the spiral elastic beam 7.

[0041] Specifically, the sensor proposed in the present application is composed of three displacement bodies with the same structure and placed orthogonally to each other. Each displacement body is connected by a base 1, forming a three-dimensional measurement system that can simultaneously detect displacements in the three directions of X, Y, and Z. When an external force is applied to cause the measuring rod 2 to move, the external force is transmitted on the first bearing part 3 and the second bearing part 4, and finally applied to the third bearing part 5 as a whole, and finally causes the spiral elastic beam 7 to produce corresponding deformation. Because of the design characteristics of the spiral elastic beam 7, it can convert a large linear displacement into a small local deformation, thereby avoiding excessive stretching or compression of the optical fiber sensor and ensuring the accuracy of the measurement. The slight deformation of the spiral elastic beam 7 will cause the length of the optical fiber segment where the optical fiber sensor is located to change, thereby changing the reflection center wavelength of the optical fiber sensor. According to the Bragg condition, the reflection center wavelength of the optical fiber sensor is related to the effective refractive index and period of the optical fiber. When the optical fiber sensor is subjected to strain, the effective refractive index and / or period of the optical fiber will change, resulting in a shift in the reflection center wavelength. The change in this wavelength is linearly related to the applied stress or displacement, so the displacement can be accurately measured by monitoring the change in wavelength. At the same time, the optical fiber sensor in this application can also monitor the change in ambient temperature. By comparing the wavelength change of the temperature compensated FBG with the actual measured FBG, the wavelength drift caused by temperature change can be separated, thereby achieving temperature compensation for displacement measurement and improving measurement accuracy.

[0042] In addition, the measuring rod 2 is connected to the first bearing part 3 by threads. This connection mode not only provides mechanical stability, but also allows the user to easily replace the measuring rod 2 of different lengths according to different measurement requirements. Another advantage of the threaded connection is that it can transmit precise linear displacement to ensure the accuracy of the measurement. The second bearing part 4 and the third bearing part 5 are also threadedly connected by a connecting rod. This design allows the relative position between the two parts to be finely adjusted, and also facilitates disassembly and reassembly. The strength and stability of the threaded connection ensure that it will not loosen easily during use, thereby maintaining the reliability of the measurement.

[0043] The first spring 6 is located between the first bearing part 3 and the second bearing part 4, and plays a role of buffering and resetting. When an external force acts on the measuring rod 2, the first spring 6 will be compressed or stretched to transfer the external force to the second bearing part 4. The existence of the spring not only helps to absorb the impact force, but also ensures that the displacement body returns to the initial position when there is no external force. In addition, the elastic coefficient of the spring is carefully designed to ensure that it can work within an appropriate range, neither over-compressed nor over-stretched, thereby protecting the spiral elastic beam 7 from damage.

[0044] Since each displacement body is an independent module, users can maintain or upgrade a displacement body without affecting other parts. For example, if a displacement body is damaged, users can replace only the displacement body without replacing the entire sensor. This modular design not only reduces maintenance costs, but also extends the service life of the sensor. In addition, by disassembling and reassembling the displacement body, users can choose different measurement configurations according to specific application scenarios. For example, in some cases, users may only need to perform two-dimensional or one-dimensional displacement measurements. At this time, the system structure can be simplified by disassembling unnecessary displacement bodies to reduce complexity and cost.

[0045] In an optional embodiment, the spiral elastic beam 7 is composed of a first fixed portion 71, a second fixed portion 72, and a second spring 73, wherein the first fixed portion 71 and the second fixed portion 72 are connected via the second spring 73, the other end of the first fixed portion 71 is fixedly connected to the third bearing portion 5, and the other end of the second fixed portion 72 is fixedly connected to the bottom, wherein the second spring 73 can be made of spring steel (65Si2MnWa) with good elastic properties and strong fatigue resistance.

[0046] The design of the spiral elastic beam 7 enables it to maintain a small local deformation under the condition of large displacement. The presence of the second spring 73 further enhances this characteristic. When an external force acts on the measuring rod 2, the displacement will be transmitted to the third bearing part 5 through the first bearing part 3 and the first spring 6, and then to the first fixing part 71. At this time, the second spring 73 will be stretched or compressed accordingly according to the applied displacement, so that the spiral elastic beam 7 will produce a small deformation. This design effectively converts large displacement into small deformation that is easier to detect, avoids excessive stretching or compression of the optical fiber sensor, and ensures high sensitivity and linearity of the measurement.

[0047] Due to the presence of the second spring 73, the spiral elastic beam 7 can withstand a larger displacement range without exceeding its elastic limit, which allows the sensor to perform accurate measurements within a wider displacement range and is suitable for application scenarios that require large-scale displacement detection, such as deformation monitoring of power towers and spacecraft structural health monitoring.

[0048] In an optional embodiment, the optical fiber sensor includes three FBG optical fiber sensors 11, wherein one FBG optical fiber sensor 11 is pasted on one side of the second spring 73, another FBG optical fiber sensor 11 is pasted on the other side of the second spring 73, and the last FBG optical fiber sensor 11 is located between the FBG optical fiber sensors. The two FBG optical fiber sensors 11 pasted on the second spring 73 are used to detect slight deformations of the second spring 73, and one FBG optical fiber sensor 11 is used to detect external temperature changes at the second spring 73, wherein the FBG optical fiber sensor 11 is pasted on the second spring 73 by an optical fiber adhesive, and the optical fiber adhesive includes epoxy resin.

[0049] Specifically, two FBG optical fiber sensors 11 are respectively attached to the two sides of the second spring 73 to form a symmetrical arrangement. This symmetrical design enables the two FBGs to simultaneously sense the slight deformation of the second spring 73 and can verify each other to ensure the accuracy of the measurement results. When an external force acts on the measuring rod 2, the second spring 73 will be stretched or compressed, causing its length and shape to change. The two FBGs will produce corresponding wavelength changes according to the deformation of the spring. By monitoring the wavelength changes of the two FBGs, the actual displacement of the second spring 73 can be accurately calculated.

[0050] In addition, since the two FBG optical fiber sensors 11 are located on both sides of the second spring 73, they can detect the symmetrical deformation of the spring, thereby effectively eliminating the asymmetric error caused by manufacturing error or asymmetric installation. If only one FBG is attached to one side of the spring, the measurement result may be biased due to uneven local stress, but by symmetrically arranging the two FBGs, the measurement result can be ensured to be more reliable and stable.

[0051] In addition, a slight deformation of the second spring 73 will cause a change in the central wavelength of the FBG reflection, and the symmetrical arrangement of the two FBGs makes this wavelength change more sensitive and linear. By calculating the average value of the wavelength changes of the two FBGs, the sensitivity and linearity of the measurement can be further improved, ensuring high accuracy within the entire measurement range.

[0052] Since temperature is one of the important factors affecting the wavelength change of FBG, the change of ambient temperature will cause the refractive index and period of FBG to change, thus causing wavelength drift. In order to eliminate the influence of temperature change on the measurement results, an FBG optical fiber sensor 11 is set up specifically for temperature compensation. Since the third FBG is not directly involved in the strain detection caused by displacement, but focuses on monitoring temperature changes, it can provide an independent temperature reference signal. By comparing the wavelength changes of the temperature compensation FBG and the two FBGs used for deformation detection, the wavelength drift caused by temperature changes can be separated, thereby realizing temperature compensation for displacement measurement. This design ensures that the sensor can maintain high-precision displacement measurement even in an environment with large temperature fluctuations.

[0053] Furthermore, a displacement body housing 14 is composed of the circular slide rail housing 8 and the slide rail housing with a base 9 , and the displacement body is sleeved in the displacement body housing 14 .

[0054] The circular slide rail housing 8 and the base slide rail housing 9 together constitute a closed protective space, which wraps the displacement body part inside the inner displacement body housing 14, leaving only the measuring rod 2 part exposed to the outside. This design effectively prevents external dust, moisture, corrosive gases and other harmful substances from entering the sensor, protects sensitive components such as FBG optical fiber sensor 11 from physical damage or chemical corrosion, and extends the service life of the sensor.

[0055] Furthermore, the grating displacement sensor also includes a main body shell 10, the base 1 is arranged inside the main body shell 10, and the main body shell 10 is provided with through holes 13 in three directions for the displacement body to pass through, and the main body shell 10 provides protection for the optical fiber sensor.

[0056] Furthermore, the optical fiber with the optical fiber sensor passes through the through hole 13 and is connected to the photoelectric converter signal.

[0057] Furthermore, the change in the central wavelength of the three-dimensional fiber Bragg grating displacement sensor varies linearly with the displacement to be measured, and the displacement change can be measured by the central wavelength, wherein the expression of the central wavelength is:

[0058]

[0059] Among them, λ B is the central wavelength of FBG, k g is the strain sensitivity coefficient of the optical fiber, K1 is the elastic coefficient of the first spring, K2 is the elastic coefficient of the second spring, L is the length of the optical fiber, x is the displacement change, Δλ 1,2 is the change in the central wavelength.

[0060] In a second aspect, the present invention further provides a method for preparing the three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure, the method comprising the following steps:

[0061] S1. The measuring rod, the first bearing part, the second bearing part, the third bearing part, the circular slide rail housing, the base slide rail housing, and the main body housing are processed by stamping or CNC, and threads of corresponding nominal sizes are processed on the base slide rail housing and the circular slide rail housing, and the main body housing is reserved for the optical fiber port;

[0062] S2. A spiral elastic beam structure having an elastic coefficient of K2 is prepared by CNC or spring technology, and a first spring having an elastic coefficient of K1 is prepared by a spring technology;

[0063] S3. Weld the three sides of the base where the sensor is not installed to the three sides of the main body shell firmly;

[0064] S4. Welding the spiral elastic beam structure to the third bearing portion;

[0065] S5. Weld three spiral elastic beam structures with metal sliders to the base in the X, Y, and Z axis directions, and install four sliders in each direction through threaded connections at the slider holes;

[0066] S6. Apply appropriate strain to the spiral elastic beam structure with a metal slider, and use epoxy resin to stick FBGs on both sides of the spiral elastic beam structure, and the FBG used for temperature compensation is located between the two FBGs measuring displacement;

[0067] S7. Install the remaining three surfaces of the main body shell and fix them through a threaded slide rod to form a spiral elastic beam structure three-dimensional fiber Bragg grating displacement sensor body;

[0068] S8. Welding the first bearing portion, the second bearing portion and the spring;

[0069] S9. The measuring rod is connected to the first bearing portion by a thread, and measuring rods of different sizes are replaced according to different measurement requirements to form a spring slider integrated structure;

[0070] S10. The spring slider integrated structure is installed into the circular slide housing, the circular slide housing and the slide housing with the base are connected by threads to seal the spring slider integrated structure to form an external removable spring displacement measurement structure;

[0071] S11. Install the external detachable spring displacement measurement structure on the reserved installation opening of the three-dimensional fiber Bragg grating displacement sensor body shell through a threaded sliding rod to make a three-dimensional fiber Bragg grating displacement sensor.

[0072] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. The protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure, characterized in that: The grating displacement sensor is composed of an optical fiber with an optical fiber sensor and three displacement bodies with the same structure, which are placed orthogonally to each other. The displacement bodies are connected to each other through a base. The displacement body is composed of a measuring rod, a first bearing part, a second bearing part, a third bearing part, a first spring, and a spiral elastic beam. The measuring rod is threadedly connected to the first bearing part, the first bearing part and the second bearing part are connected through the first spring, the second bearing part and the third bearing part are threadedly connected, and the third bearing part is fixedly connected to the bottom through a spiral elastic beam. The part of the optical fiber with the optical fiber sensor is pasted on the spiral elastic beam to detect slight deformation and temperature changes of the spiral elastic beam.

2. A three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure according to claim 1, characterized in that: The spiral elastic beam consists of a first fixing part, a second fixing part, and a second spring, wherein the first fixing part and the second fixing part are connected via the second spring, the other end of the first fixing part is fixedly connected to the third bearing part, and the other end of the second fixing part is fixedly connected to the bottom.

3. The three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure according to claim 2, characterized in that: The optical fiber sensor includes three FBG optical fiber sensors, one of which is pasted on one side of the second spring, another FBG optical fiber sensor is pasted on the other side of the second spring, and the last FBG optical fiber sensor is located between the other two FBG optical fiber sensors. The two FBG optical fiber sensors pasted on the second spring are used to detect slight deformations of the second spring, and one FBG optical fiber sensor is used to detect external temperature changes at the second spring.

4. The three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure according to claim 2, characterized in that: The displacement body shell is composed of a circular slide rail shell and a slide rail shell with a base, and the displacement body is sleeved in the displacement body shell.

5. The three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure according to claim 2, characterized in that: The grating displacement sensor also includes a main body shell, the base is arranged inside the main body shell, and through holes for the displacement body to pass through are arranged in three directions of the main body shell.

6. The three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure according to claim 5, characterized in that: The optical fiber with the optical fiber sensor passes through the through hole and is connected to the photoelectric converter signal.

7. The three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure according to claim 3, characterized in that: The FBG optical fiber sensor is adhered to the second spring by means of an optical fiber adhesive, wherein the optical fiber adhesive comprises epoxy resin.

8. A three-dimensional fiber Bragg grating displacement sensor with a spiral elastic beam structure according to any one of claims 1 to 7, characterized in that: The change in the central wavelength of the three-dimensional fiber Bragg grating displacement sensor changes linearly with the displacement to be measured, and the displacement change can be measured by the central wavelength, wherein the expression of the central wavelength is: Among them, λ B is the central wavelength of FBG, K g is the strain sensitivity coefficient of the optical fiber, K1 is the elastic coefficient of the first spring, K2 is the elastic coefficient of the second spring, L is the length of the optical fiber, x is the displacement change, Δλ 1,2 is the change in the central wavelength.

Images