Double-I-beam type two-dimensional fiber bragg grating tilt angle sensor and tilt angle measuring method thereof

Abstract

The invention provides a double-I-beam type two-dimensional fiber bragg grating tilt angle sensor, which comprises a shell and a sensing assembly, and is characterized in that the sensor assembly comprises a first mass block, a second mass block, a third mass block, a balancing weight, a first fiber bragg grating, a second fiber bragg grating, a first connecting piece with a plate-shaped structure and a second connecting piece with a plate-shaped structure; the first mass block is fixedly arranged in the shell, the lower end face of the first mass block is fixedly connected with the upper end face of the second mass block through a first connecting piece to form an I-shaped beam structure, and the lower end face of the second mass block is fixedly connected with the upper end face of the third mass block through a second connecting piece to form an I-shaped beam structure. The third mass block is fixedly embedded in the balancing weight, and the lower ends of the balancing weight and the third mass block are free ends; the plate surfaces of the first connecting piece and the second connecting piece are vertical; the first fiber bragg grating and the second fiber bragg grating are fixedly arranged on the surfaces of the two sides of the first mass block, the second mass block and the third mass block respectively and form a U-shaped structure at the lower end of the third mass block.

Description

Technical Field

[0001] The invention relates to an inclination sensor and an inclination measuring method thereof, in particular to a double I-beam type two-dimensional fiber grating inclination sensor and an inclination measuring method thereof. Background Art

[0002] Large-scale civil engineering projects such as high-rise housing projects, bridge projects, wind turbine tower structures and water tower projects are very prone to tilting due to long-term exposure to complex wind fields, seismic environments and loads. Excessive tilting and deformation will affect the normal use function of the structure. In severe cases, the structural damage caused will cause loss of life and property.

[0003] Traditional inclination sensors are mainly based on the piezoelectric / electromagnetic effect, which has poor resistance to electromagnetic interference and short transmission distance, and are not suitable for working in strong electromagnetic or electrostatic environments. Secondly, most inclination sensors are mainly unidirectional measurements, while the tilting state of engineering structures under complex environments and loads is generally unknown or multi-directional, so multiple sensors need to be deployed to realize the perception of the structural tilt state, which is costly and inefficient.

[0004] Therefore, in order to solve the above technical problems, it is urgent to propose a new technical means. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a double I-beam two-dimensional fiber grating inclination sensor and an inclination measurement method thereof, which can accurately measure the inclination angle of the target to be measured, and can sense the inclination in any direction, and has strong anti-electromagnetic interference ability, effectively reducing the interference of the environment on the measurement results, thereby having strong environmental adaptability, and can achieve high sensitivity adjustment, so that it can adapt to a variety of working conditions.

[0006] A double I-beam two-dimensional fiber Bragg grating inclination sensor provided by the present invention comprises a housing and a sensor assembly, wherein the sensor assembly comprises a first mass block, a second mass block, a third mass block, a counterweight block, a first fiber Bragg grating, a second fiber Bragg grating, a first connecting member of a plate-shaped structure, and a second connecting member of a plate-shaped structure;

[0007] The first mass block is fixedly arranged in the shell, the lower end surface of the first mass block is fixedly connected to the upper end surface of the second mass block through the first connecting member to form an I-beam structure, the lower end surface of the second mass block is fixedly connected to the upper end surface of the third mass block through the second connecting member to form an I-beam structure, the third mass block is fixedly embedded in the counterweight block, the lower ends of the counterweight block and the third mass block are free ends; the plate surfaces of the first connecting member and the second connecting member are perpendicular;

[0008] The first fiber grating and the second fiber grating are respectively fixedly arranged on the surfaces of both sides of the first mass block, the second mass block and the third mass block and form a U-shaped structure at the lower end of the third mass block.

[0009] Furthermore, the counterweight block is provided with an embedding hole, the third mass block is fixedly embedded in the embedding hole, the side wall of the embedding hole is provided with a strip groove, the length extension direction of the strip groove is consistent with the length extension direction of the embedding hole and the strip groove is used for the fiber grating to pass through.

[0010] Furthermore, the shell is provided with a limit rod and a limit hole, and the limit rod passes through the shell through the limit hole.

[0011] Furthermore, the shell is a cylindrical structure, the upper end of the shell is provided with an end cover fixedly matched with the shell, the upper end of the first mass block is fixedly connected to the inner side of the end cover, and the end cover is provided with a fiber grating guide hole.

[0012] Furthermore, the fiber Bragg grating is a pre-stretched fiber Bragg grating.

[0013] Accordingly, the present invention also provides a tilt angle measurement method based on the above tilt angle sensor, comprising the following steps:

[0014] S1. The inclination sensor is fixedly disposed on the target to be measured, and the initial structural parameters of the inclination sensor are determined;

[0015] S2. A test optical signal generated by a laser is input from one end of the fiber Bragg grating and received at the other end;

[0016] S3. Determine the tension side and compression side of the fiber Bragg grating when the target is tilted, and obtain the wavelength change of the optical signal from the optical signal passing through the fiber Bragg grating;

[0017] S4. With the direction of gravity as the ordinate, establish an OXYZ coordinate system, and determine the deflection angle θ1 in the ZOX plane of the inclination sensor and the deflection angle θ2 in the ZOY plane based on the change in the wavelength of the optical signal;

[0018] S5. Determine the inclination angle of the inclination sensor around the z-axis and the azimuth angle around the x-axis based on the deflection angle θ1 and the deflection angle θ2:

[0019]

[0020] Where: β is the inclination angle of the inclination sensor around the z-axis, and α is the azimuth angle of the inclination sensor around the x-axis.

[0021] Further, the deflection angle θ1 is determined by the following method:

[0022]

[0023] Where: Δλ1 is the wavelength change of the optical signal on the stretching side of the lower end of the first and second fiber Bragg gratings, Δλ1' is the wavelength change of the optical signal on the compression side of the lower end of the first and second fiber Bragg gratings, λ1 is the wavelength of the optical signal input at the measuring point at the lower end of the first and second fiber Bragg gratings, L1 is the length of the second connecting piece, E f is the elastic modulus of the fiber Bragg grating, A is the cross-sectional area of ​​the fiber Bragg grating, d1 is the vertical distance from the measuring point at the lower end of the first and second fiber Bragg gratings to the center line of the length direction of the second connecting member, a1 is the distance from the center of gravity of the counterweight block and the third mass block to the end face of the lower end of the third mass block, m1 is the sum of the masses of the third mass block and the counterweight block, E1 is the elastic modulus of the second connecting member, and b1 and h1 are the width and thickness of the second connecting member.

[0024] Further, the deflection angle θ2 is determined by the following method:

[0025]

[0026] Where: Δλ2 is the wavelength change of the optical signal on the stretching side of the first and second fiber Bragg gratings, Δλ2' is the wavelength change of the optical signal on the compression side of the first and second fiber Bragg gratings, λ2 is the wavelength of the optical signal input at the measuring point on the first and second fiber Bragg gratings, L1 is the length of the second connecting piece, L2 is the length of the first connecting piece, E f is the elastic modulus of the fiber Bragg grating, A is the cross-sectional area of ​​the fiber Bragg grating, d2 is the vertical distance from the upper measuring points of the first and second fiber Bragg gratings to the center line of the length direction of the first connecting member, a2 is the length of the second mass block, m2 is the mass of the second mass block, m1 is the sum of the masses of the third mass block and the counterweight block, E2 is the elastic modulus of the first connecting member, b2 and h2 are the width and thickness of the first connecting member.

[0027] The beneficial effects of the present invention are as follows: through the present invention, the inclination angle of the target can be accurately measured, and the inclination angle in any direction can be sensed, and the anti-electromagnetic interference capability is strong, which effectively reduces the interference of the environment on the measurement results, thereby having a strong environmental adaptability, and can achieve high-sensitivity adjustment, so that it can adapt to a variety of working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0029] Figure 1 It is a structural schematic diagram of the present invention.

[0030] Figure 2 It is a schematic diagram of the structure of the sensor assembly composed of the first mass block, the second mass block and the third mass block of the present invention.

[0031] Figure 3 It is a schematic diagram of the structure of the counterweight block of the present invention.

[0032] Figure 4 It is a schematic diagram for explaining parameters of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below:

[0034] A double I-beam two-dimensional fiber Bragg grating inclination sensor provided by the present invention comprises a housing 1 and a sensor assembly 3, wherein the sensor assembly comprises a first mass block 7, a second mass block 8, a third mass block 9, a counterweight block 4, a first fiber Bragg grating 5, a second fiber Bragg grating 10, a first connecting member 11 of a plate-shaped structure, and a second connecting member 12 of a plate-shaped structure;

[0035] The first mass block 7 is fixedly arranged in the housing 1, the lower end surface of the first mass block 7 is fixedly connected to the upper end surface of the second mass block 8 through the first connecting member 11 to form an I-beam structure, the lower end surface of the second mass block 8 is fixedly connected to the upper end surface of the third mass block 9 through the second connecting member 12 to form an I-beam structure, the third mass block 9 is fixedly embedded in the counterweight block 4, and the lower ends of the counterweight block 4 and the third mass block 9 are free ends; the plate surfaces of the first connecting member 11 and the second connecting member 12 are perpendicular;

[0036] The first fiber Bragg grating 5 and the second fiber Bragg grating 10 are respectively fixedly arranged on the surfaces of the first mass block, the second mass block and the third mass block on both sides and form a U-shaped structure at the lower end of the third mass block. Among them, by adjusting the different masses of the counterweight block, the sensitivity of the entire sensor can be adjusted. Through the above structure, the tilt angle of the measured target can be accurately measured, and the tilt angle in any direction can be sensed. In addition, the anti-electromagnetic interference ability is strong, and the interference of the environment on the measurement result is effectively reduced, so that it has a strong environmental adaptability and can achieve high sensitivity adjustment, so that it can adapt to a variety of working conditions.

[0037] In this embodiment, the counterweight block 4 is provided with an embedding hole 4.3, and the third mass block 9 is embedded in the embedding hole 4.3, wherein the counterweight block 4 and the third mass block 9 are both provided with corresponding threaded holes and are fixed by bolts (the threaded hole of the counterweight block is 4.1, and the threaded hole of the third mass block is 3.2), and the side wall of the embedding hole is provided with a strip groove 4.2, the length extension direction of the strip groove is consistent with the length extension direction of the embedding hole and the strip groove is used for the passage of the optical fiber Bragg grating. Through this structure, the layout of the optical fiber Bragg grating is convenient, and the sensitivity of the entire sensor can be adjusted by applying different counterweight blocks.

[0038] In this embodiment, the shell is provided with a limit rod 6, and the limit rod passes through the shell 1. The limit rod is fully tightened to just contact the counterweight block to prevent swinging. When in use, the limit rod can be taken out. Through this structure, the sensor can prevent the fiber grating from being over-stretched when it is not in use such as transportation, thereby reducing the final measurement accuracy.

[0039] In this embodiment, the shell is a cylindrical structure, and the upper end of the shell is provided with an end cover 2 fixedly matched with the shell. The upper end of the first mass block is fixedly connected to the inner side of the end cover, and the end cover is provided with a fiber grating guide hole. As shown in the figure, the end cover is provided with a fixing hole 2.2, and the shell 1 and the end cover 2 are fixed with bolts. The first mass block is also provided with a connecting hole 3.1 for fixing the first mass block and the end cover with bolts.

[0040] In this embodiment, the fiber Bragg grating is a pre-stretched fiber Bragg grating.

[0041] Accordingly, the present invention also provides a tilt angle measurement method based on the above tilt angle sensor, comprising the following steps:

[0042] S1. The inclination sensor is fixedly disposed on the target to be measured, and the initial structural parameters of the inclination sensor are determined;

[0043] S2. A test optical signal generated by a laser is input from one end of the fiber Bragg grating and received at the other end;

[0044] S3. Determine the tension side and compression side of the fiber Bragg grating when the target is tilted, and obtain the wavelength change of the optical signal from the optical signal passing through the fiber Bragg grating;

[0045] S4. With the direction of gravity as the ordinate, establish an OXYZ coordinate system, and determine the deflection angle θ1 in the ZOX plane of the inclination sensor and the deflection angle θ2 in the ZOY plane based on the change in the wavelength of the optical signal;

[0046] S5. Determine the inclination angle of the inclination sensor around the z-axis and the azimuth angle around the x-axis based on the deflection angle θ1 and the deflection angle θ2:

[0047]

[0048] Wherein: β is the inclination angle of the inclination sensor around the z-axis, and α is the azimuth angle of the inclination sensor around the x-axis. That is to say, the inclination in any direction of the measured target can be determined by the composite amount of the above two deflection angles.

[0049] In this embodiment, the deflection angle θ1 is determined by the following method:

[0050]

[0051] Where: Δλ1 is the wavelength change of the optical signal on the stretching side of the lower end of the first and second fiber Bragg gratings, Δλ1' is the wavelength change of the optical signal on the compression side of the lower end of the first and second fiber Bragg gratings, λ1 is the wavelength of the optical signal input at the measuring point at the lower end of the first and second fiber Bragg gratings, L1 is the length of the second connecting piece, E f is the elastic modulus of the fiber Bragg grating, A is the cross-sectional area of ​​the fiber Bragg grating, d1 is the vertical distance from the measuring point at the lower end of the first and second fiber Bragg gratings to the center line of the length direction of the second connecting member, a1 is the distance from the center of gravity of the counterweight block and the third mass block to the end face of the lower end of the third mass block, m1 is the sum of the masses of the third mass block and the counterweight block, E1 is the elastic modulus of the second connecting member, and b1 and h1 are the width and thickness of the second connecting member.

[0052] Further, the deflection angle θ2 is determined by the following method:

[0053]

[0054] Where: Δλ2 is the wavelength change of the optical signal on the stretching side of the first and second fiber Bragg gratings, Δλ2' is the wavelength change of the optical signal on the compression side of the first and second fiber Bragg gratings, λ2 is the wavelength of the optical signal input at the measuring point on the first and second fiber Bragg gratings, L1 is the length of the second connecting piece, L2 is the length of the first connecting piece, E f is the elastic modulus of the fiber Bragg grating, A is the cross-sectional area of ​​the fiber Bragg grating, d2 is the vertical distance from the upper measuring points of the first and second fiber Bragg gratings to the center line of the length direction of the first connecting member, a2 is the length of the second mass block, m2 is the mass of the second mass block, m1 is the sum of the masses of the third mass block and the counterweight block, E2 is the elastic modulus of the first connecting member, b2 and h2 are the width and thickness of the first connecting member.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A double I-beam two-dimensional fiber Bragg grating inclination sensor, characterized in that: The sensor assembly comprises a housing and a sensor component, wherein the sensor assembly comprises a first mass block, a second mass block, a third mass block, a counterweight block, a first fiber grating, a second fiber grating, a first connecting member of a plate-shaped structure, and a second connecting member of a plate-shaped structure; The first mass block is fixedly arranged in the shell, the lower end surface of the first mass block is fixedly connected to the upper end surface of the second mass block through the first connecting member to form an I-beam structure, the lower end surface of the second mass block is fixedly connected to the upper end surface of the third mass block through the second connecting member to form an I-beam structure, the third mass block is fixedly embedded in the counterweight block, the lower ends of the counterweight block and the third mass block are free ends; the plate surfaces of the first connecting member and the second connecting member are perpendicular; The first fiber grating and the second fiber grating are respectively fixedly arranged on the surfaces of both sides of the first mass block, the second mass block and the third mass block and form a U-shaped structure at the lower end of the third mass block.

2. The double I-beam two-dimensional fiber Bragg grating inclination sensor according to claim 1, characterized in that: The counterweight block is provided with an embedding hole, the third mass block is fixedly embedded in the embedding hole, the side wall of the embedding hole is provided with a strip groove, the length extension direction of the strip groove is consistent with the length extension direction of the embedding hole and the strip groove is used for the fiber grating to pass through.

3. The double I-beam two-dimensional fiber Bragg grating inclination sensor according to claim 1, characterized in that: The shell is provided with a limiting rod and a limiting hole, and the limiting rod passes through the shell through the limiting hole.

4. The double I-beam two-dimensional fiber Bragg grating inclination sensor according to claim 1, characterized in that: The shell is a cylindrical structure, the upper end of the shell is provided with an end cover fixedly matched with the shell, the upper end of the first mass block is fixedly connected to the inner side of the end cover, and the end cover is provided with a fiber grating guide hole.

5. The double I-beam two-dimensional fiber Bragg grating inclination sensor according to claim 1, characterized in that: The optical fiber Bragg grating is a pre-stretched optical fiber Bragg grating.

6. A method for measuring inclination angle based on the inclination sensor according to claim 1, characterized in that: The following steps are involved: S1. The inclination sensor is fixedly disposed on the target to be measured, and the initial structural parameters of the inclination sensor are determined; S2. A test optical signal generated by a laser is input from one end of the fiber Bragg grating and received at the other end; S3. Determine the tension side and compression side of the fiber Bragg grating when the target is tilted, and obtain the wavelength change of the optical signal from the optical signal passing through the fiber Bragg grating; S4. With the direction of gravity as the ordinate, establish an OXYZ coordinate system, and determine the deflection angle θ1 in the ZOX plane of the inclination sensor and the deflection angle θ2 in the ZOY plane based on the change in the wavelength of the optical signal; S5. Determine the inclination angle of the inclination sensor around the z-axis and the azimuth angle around the x-axis based on the deflection angle θ1 and the deflection angle θ2: Where: β is the inclination angle of the inclination sensor around the z-axis, and α is the azimuth angle of the inclination sensor around the x-axis.

7. The inclination angle measuring method according to claim 6 based on the inclination angle sensor according to claim 1 is characterized in that: The deflection angle θ1 is determined by the following method: Where: Δλ1 is the wavelength change of the optical signal on the stretching side of the lower end of the first and second fiber Bragg gratings, Δλ1' is the wavelength change of the optical signal on the compression side of the lower end of the first and second fiber Bragg gratings, λ1 is the wavelength of the optical signal input at the measuring point at the lower end of the first and second fiber Bragg gratings, L1 is the length of the second connecting piece, E f is the elastic modulus of the fiber Bragg grating, A is the cross-sectional area of ​​the fiber Bragg grating, d1 is the vertical distance from the measuring point at the lower end of the first and second fiber Bragg gratings to the center line of the length direction of the second connecting member, a1 is the distance from the center of gravity of the counterweight block and the third mass block to the end face of the lower end of the third mass block, m1 is the sum of the masses of the third mass block and the counterweight block, E1 is the elastic modulus of the second connecting member, and b1 and h1 are the width and thickness of the second connecting member.

8. According to claim 6, the inclination angle measuring method based on the inclination angle sensor according to claim 1 is characterized in that: The deflection angle θ2 is determined by the following method: Where: Δλ2 is the wavelength change of the optical signal on the stretching side of the first and second fiber Bragg gratings, Δλ2' is the wavelength change of the optical signal on the compression side of the first and second fiber Bragg gratings, λ2 is the wavelength of the optical signal input at the measuring point on the first and second fiber Bragg gratings, L1 is the length of the second connecting piece, L2 is the length of the first connecting piece, E f is the elastic modulus of the fiber Bragg grating, A is the cross-sectional area of ​​the fiber Bragg grating, d2 is the vertical distance from the upper measuring points of the first and second fiber Bragg gratings to the center line of the length direction of the first connecting member, a2 is the length of the second mass block, m2 is the mass of the second mass block, m1 is the sum of the masses of the third mass block and the counterweight block, E2 is the elastic modulus of the first connecting member, b2 and h2 are the width and thickness of the first connecting member.

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