A fiber grating type static water level instrument calibration experiment model

Abstract

The utility model belongs to engineering surveying technical field, propose a kind of fiber grating type static level gauge calibration experiment model. It includes base, multiple stand is fixed vertically on base, fiber grating type static level gauge of adjustable height is installed on stand, and stand is equipped with locking structure and fixes level gauge height. Adjacent stand is fixedly connected through crossbeam, and forms stable frame. Demodulator is connected each level gauge through optical cable and is connected with host computer, and liquid storage tank is connected with each level gauge cavity series communication by silica gel liquid passage. Each stand installs micrometer, and its measuring rod is vertically contacted with the upper surface of level gauge. The model is with adjustable level gauge, stable frame structure, real-time data acquisition system and micrometer benchmark measurement, provides stable quantifiable benchmark for level gauge precision calibration, effectively ensures the accuracy of height parameter in calibration process.

Description

Technical Field

[0001] This utility model belongs to the field of engineering measurement technology, specifically relating to a calibration experimental model of a fiber optic grating hydrostatic level. Background Technology

[0002] Fiber Bragg gratings (FBGs) possess outstanding advantages such as excellent electrical insulation, corrosion resistance, strong electromagnetic interference resistance, and high durability. These advantages have led to the widespread application of FBG hydrostatic levels, which integrate FBG sensing and settlement measurement technologies, in monitoring uneven settlement of large structures. These devices can accurately measure settlement differences at various measuring points in large-scale projects such as hydropower plant buildings, dams, nuclear power plants, water conservancy projects, and tank foundations.

[0003] Before practical application, fiber Bragg grating hydrostatic levels must undergo calibration experiments to determine key parameters such as sensitivity. However, traditional calibration experimental models for fiber Bragg grating hydrostatic levels have significant shortcomings: traditional calibration devices employ a sequential calibration approach, requiring the removal of the calibrated instrument after each calibration before installing the next. This method is not only time-consuming, but also problematic, especially for instruments from the same batch. The excessively long calibration cycle can lead to changes in the calibration environment over time (such as temperature fluctuations and differences in equipment stability), introducing substantial environmental errors. Therefore, redesigning a calibration experimental model for fiber Bragg grating hydrostatic levels to improve calibration efficiency is essential. Utility Model Content

[0004] In order to overcome the shortcomings of the existing technology, this utility model proposes a calibration experimental model for a fiber optic grating hydrostatic level.

[0005] To achieve the above objectives, the present invention proposes the following technical content:

[0006] A calibration experimental model for a fiber optic grating hydrostatic level includes the following structure:

[0007] Base;

[0008] Multiple columns are vertically fixed to the upper surface of the base; multiple fiber Bragg grating hydrostatic levels are installed on each column, and the height of each fiber Bragg grating hydrostatic level can be adjusted. Each column is equipped with a locking structure for locking the height of the fiber Bragg grating hydrostatic level; all fiber Bragg grating hydrostatic levels are set at the same height.

[0009] Multiple crossbeams are fixedly connected to two adjacent columns;

[0010] The demodulator is connected to multiple fiber optic grating hydrostatic levels via optical cables, and is also connected to a host computer.

[0011] The liquid storage tank is connected in series with the cavities of multiple fiber optic hydrostatic levels through silicone liquid-passing pipes to form a liquid flow loop.

[0012] Multiple micrometers are mounted on each column, with the measuring rod of each micrometer in perpendicular contact with the upper surface of the fiber optic grating hydrostatic level.

[0013] Furthermore, the locking structure includes: a locking hole opened on the support of the fiber optic grating static level, a Phillips bolt passing through the drilled hole of the column, the Phillips bolt passing through the locking hole, and a nut screwed onto the Phillips bolt, for limiting the height of the fiber optic grating static level after it has been adjusted to a certain height.

[0014] A star bolt passes through a locking hole on the fiber optic grating static level's support, and is then tightened with a nut. This method allows the level to be precisely locked at a specific height. The star bolt and nut provide a large tightening force, effectively preventing height changes due to vibration or external forces during experiments, ensuring the accuracy and reliability of experimental data. During calibration experiments, the level's height can be easily changed by loosening the nut and adjusting the position of the star bolt in the locking hole. After adjustment, tightening the nut secures the level. This simple operation quickly meets the experimental needs of different height settings. This locking structure ensures a tight connection between the level and the column, evenly distributing the level's weight onto the column. Combined with the support of the base and crossbeam, this further enhances the stability of the entire experimental model, helping to reduce interference from external factors on the experimental results. The combination of star bolts and nuts is a common standard connection method. Installation and disassembly require no special tools; ordinary wrenches and other tools can be used, facilitating the assembly, debugging, and subsequent maintenance of the experimental model.

[0015] Furthermore, bolt holes are pre-drilled on both the crossbeam and the column, and the column and the crossbeam are detachably connected by bolts.

[0016] The bolted connection eliminates the need for complex tools in installing and disassembling the columns and beams, making the operation simple and efficient. Researchers can quickly assemble or disassemble the structure according to calibration requirements, significantly improving the flexibility of model building. Precisely machined bolt holes on the beams and columns ensure accurate positioning during connection, reducing assembly errors. Tightened bolts provide reliable connection strength, preventing displacement or deformation due to structural loosening during experiments, ensuring the stability of the entire experimental model, and indirectly improving the reliability of calibration data.

[0017] Furthermore, the beams are divided into upper and lower layers, with four columns and a total of eight beams, four beams per layer.

[0018] Four columns, along with eight crossbeams (four per layer), form a double-layered three-dimensional frame structure. Compared to a single-layered crossbeam, the double-layered design provides more balanced constraints on the columns in the vertical direction (upper and lower layers), effectively resisting horizontal swaying or deformation of the columns. This significantly improves the torsional resistance and stability of the entire experimental model and reduces the impact of structural deformation on the leveling instrument's calibration accuracy.

[0019] Furthermore, from a top-down perspective, the four pillars are located at the four corners of the rectangle.

[0020] The rectangular layout has natural symmetry. When the four columns are located at the four corners of the rectangle, the forces on each column (such as the tension from the crossbeam, the gravity of the level and the micrometer) can be evenly transmitted to the entire frame through the crossbeam. This avoids localized stress concentration caused by the asymmetrical layout, significantly improves the overall structure's resistance to deformation and stability, and provides a more solid foundation for calibration experiments.

[0021] Furthermore, the micrometer is mounted to the column using bolt-type clamps.

[0022] The bolt-type clamps firmly fix the micrometer to the column through the tightening force of the bolts, which can effectively prevent the micrometer from shifting or shaking due to vibration, collision or operation during the measurement process. This ensures that the micrometer measuring rod and the upper surface of the fiber optic grating static level always maintain stable vertical contact, providing accurate and reliable reference data for height measurement.

[0023] The beneficial effects that can be achieved by adopting the above technologies are:

[0024] 1. Multiple fiber optic grating static levels can be adjusted in height and set at equal heights via the column. Combined with the precise height measurement by a micrometer (the measuring rod is in perpendicular contact with the upper surface of the level), a stable and quantifiable benchmark can be provided for the accuracy calibration of the level, ensuring the accuracy of the height parameters during the calibration process.

[0025] 2. The demodulator connects to multiple levels via optical fiber and is linked with the host computer. It can collect real-time sensor data (such as wavelength changes) from fiber optic gratings. Combined with the liquid flow loop formed by the storage tank and the silicone liquid pipe, it can simultaneously monitor the correspondence between liquid level changes and sensor responses, realizing automated, high-precision recording and analysis of calibration data.

[0026] 3. The base provides stable support, and multiple crossbeams are fixedly connected to adjacent columns to form a rigid frame structure, which effectively reduces the impact of external vibration or deformation on the level and micrometer, ensuring that the calibration experiment is carried out in a stable environment and improving the reliability of the calibration results.

[0027] 4. The height of the level instrument can be fixed by a locking structure, and the micrometer can be installed flexibly, making it easy to adjust experimental parameters according to different calibration requirements (such as different height differences or different combinations of levels). It is suitable for the calibration of various models or specifications of fiber optic grating static levels, enhancing the versatility and reusability of the model. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the device.

[0029] 1. Base; 2. Column; 3. Horizontal beam; 4. Fiber optic grating hydrostatic level; 5. Snap-in hole; 6. Torx bolt; 7. Dial indicator; 8. Liquid storage tank; 9. Demodulator; 10. Host computer. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0031] Example 1: A calibration experimental model for a fiber optic grating hydrostatic level includes a base 1. Multiple columns 2 are fixedly connected to the upper surface of the base 1 by welding. The columns 2 are calibrated for verticality during installation to ensure they are all perpendicular to the upper surface of the base 1. In this example, there are four columns 2, located at the four vertices of a rectangle from a top-down view. Adjacent columns 2 are fixedly connected by horizontally arranged beams 3, specifically using screw holes and bolts. There are two sets of beams 3, arranged in two layers, with four beams 3 in each layer. In the top-down view, the projection of the four beams 3 in each layer is rectangular. Specifically, the beams 3 and columns 2 are bolted together to form a detachable rigid rectangular frame structure. Bolt holes are pre-drilled on both the beams 3 and columns 2 to ensure the beams 3 are horizontal after connection.

[0032] Each column is equipped with a fiber Bragg grating static level 4 to be calibrated. After installation, the four fiber Bragg grating static levels 4 are ensured to be at the same height using relevant instruments (such as a laser level). Specifically, each of the four fiber Bragg grating static levels 4 has a strip-shaped locking hole 5 on its support. The locking holes 5 are distributed vertically and are slightly higher than 100mm. Each column 2 has a drilled hole through which a Phillips head bolt 6 is inserted. The shank of the Phillips head bolt is also inserted into the strip-shaped locking hole. The nut 6 is screwed onto the Phillips head bolt to make the nut fit tightly against the support surface. Thus, the four fiber Bragg grating static levels are installed on the corresponding columns by friction. Loosening the nut disables the installation function, but allows for height adjustment of the fiber optic grating hydrostatic level. During adjustment, the position of the Torx bolt remains unchanged, while the fiber optic grating hydrostatic level moves vertically. Because the locating hole 5 is a precision-machined strip hole (ignoring the influence of small gaps), the smooth vertical displacement characteristic is consistently maintained during adjustment. Furthermore, based on the length of the locating hole 5, the adjustable range of the fiber optic grating hydrostatic level is set to 0-100mm.

[0033] A storage tank 8 is fixedly connected to a crossbeam at the bottom position via a clamp. The cavities of the four fiber optic hydrostatic levels 4 and the storage tanks are connected in series via silicone water pipes, forming a liquid (water) flow loop. The connection path is: storage tank → level one → level two → level three → level four → storage tank.

[0034] Four dial indicators 7 are each mounted on their corresponding supports 2 using bolt-type clamps. Each dial indicator is positioned above its corresponding fiber Bragg grating hydrostatic level. The measuring rod of the dial indicator is in perpendicular contact with the upper surface of the fiber Bragg grating hydrostatic level's support, used to measure the height change of the fiber Bragg grating hydrostatic level. The top of each dial indicator has a bubble level. When the dial indicator is level, since the aforementioned fiber Bragg grating hydrostatic level has also been calibrated using a laser level, the measuring rod of the dial indicator will inevitably be in perpendicular contact with the upper surface of the fiber Bragg grating hydrostatic level's support.

[0035] All fiber Bragg grating hydrostatic levels are connected to a single demodulator via optical fiber. This demodulator has a multi-channel synchronous acquisition function, which can simultaneously acquire wavelength data from each fiber Bragg grating hydrostatic level.

[0036] The demodulator is connected to the host computer 10, which has a data processing and display module. The host computer can process data and allow experimental personnel to observe and analyze experimental data in real time.

[0037] Calibration process of this device

[0038] The calibration personnel fill the storage tank with distilled water, which then fills the cavity of each fiber optic grating hydrostatic level through the silicone liquid-passing tube. They check the airtightness of the interface to ensure that there is no liquid leakage, and at the same time, ensure that there are no air bubbles in the silicone liquid-passing tube.

[0039] The calibration personnel conducted a positive cycle experiment, which involved loosening the nuts and manually fine-tuning the height X of all fiber optic hydrostatic levels multiple times (e.g., 9 times) (each adjustment being 10mm). This process continuously lowered the height of the fiber optic hydrostatic levels to their lowest possible positions. Each time the height of the fiber optic hydrostatic level was adjusted manually, the calibration personnel closely monitored the dial gauge reading. Once the distance change reached X, the nuts were tightened to ensure the fiber optic hydrostatic level no longer shifted. Multiple fiber optic hydrostatic levels were simultaneously lowered by multiple calibration personnel, maintaining equal heights. After each height adjustment, the wavelength data of each fiber optic hydrostatic level was read using a demodulator, until 10 sets of wavelength data (each set containing four wavelengths) were obtained after 10 adjustments.

[0040] The calibration personnel conducted a reverse cycle experiment, which involved loosening the nut and manually fine-tuning the height X of the fiber Bragg grating hydrostatic level multiple times (e.g., 9 times, the same number of times as in the forward cycle experiment) (each adjustment distance was 10mm, the same distance as in the forward cycle experiment). This allowed the height of the fiber Bragg grating hydrostatic level to gradually increase from the aforementioned low position. Each time the height of the fiber Bragg grating hydrostatic level was fine-tuned manually, the calibration personnel closely monitored the dial gauge reading. When the distance change reached X, the nut was tightened to ensure that the fiber Bragg grating hydrostatic level no longer shifted. Multiple fiber Bragg grating hydrostatic levels were raised in height through adjustments by multiple calibration personnel, ensuring that the height of each fiber Bragg grating hydrostatic level remained constant when it passed the nut locking position. After each height adjustment, the wavelength data of each fiber Bragg grating hydrostatic level was read using a demodulator until 10 adjustments were made, resulting in 10 sets of wavelength data (each set containing four wavelengths).

[0041] After obtaining 10 sets of forward wavelength data and 10 sets of reverse wavelength data, the forward and reverse wavelength data of any fiber Bragg grating hydrostatic level can be obtained. This allows for the calculation of the calibration parameters (hysteresis error and linearity of the forward data) for each fiber Bragg grating hydrostatic level. These two parameters are existing technologies in the field of sensor calibration; calibration methods can be found in textbooks such as "Sensor Principles and Applications," and will not be elaborated upon here.

[0042] The matrix composed of 10 sets of forward wavelength data is as follows:

[0043]

[0044] The matrix composed of 10 sets of backflight wavelength data is as follows:

[0045]

[0046] In the formula, λ FS This represents the full-scale wavelength variation. This indicates taking the maximum value. ξ H,i This indicates hysteresis error.

[0047]

[0048] In the formula, The wavelength value is the positive equation fitting value; ζ H ,i represents the linearity of the forward data.

[0049] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A calibration experimental model for a fiber optic grating hydrostatic level, characterized in that, Includes the following structure: Base; Multiple columns are vertically fixed to the upper surface of the base; multiple fiber Bragg grating hydrostatic levels are installed on each column, and the height of each fiber Bragg grating hydrostatic level can be adjusted. Each column is equipped with a locking structure for locking the height of the fiber Bragg grating hydrostatic level; all fiber Bragg grating hydrostatic levels are set at the same height. Multiple crossbeams, each of which is fixedly connected to two adjacent columns; The demodulator is connected to multiple fiber optic grating hydrostatic levels via optical cables, and is also connected to a host computer. The liquid storage tank is connected in series with the cavities of multiple fiber optic hydrostatic levels through silicone liquid-passing pipes to form a liquid flow loop. Multiple micrometers are mounted on each column, with the measuring rod of each micrometer in perpendicular contact with the upper surface of the fiber optic grating hydrostatic level.

2. The fiber optic grating hydrostatic level calibration experimental model according to claim 1, characterized in that, The locking structure includes: a locking hole on the support of the fiber optic grating static level, a Phillips bolt passing through the drilled hole in the column, the Phillips bolt passing through the locking hole, and a nut screwed onto the Phillips bolt, used to limit the height of the fiber optic grating static level after it has been adjusted to a certain height.

3. The fiber optic grating hydrostatic level calibration experimental model according to claim 2, characterized in that, Both the crossbeam and the column have pre-drilled bolt holes, and the column and the crossbeam are detachably connected by bolts.

4. The fiber optic grating hydrostatic level calibration experimental model according to claim 3, characterized in that, The beams are divided into upper and lower layers, with 4 columns and a total of 8 beams, with 4 beams on each layer.

5. The fiber optic grating hydrostatic level calibration experimental model according to claim 4, characterized in that, From a top-down view, the four pillars are located at the four corners of the rectangle.

6. The fiber optic grating hydrostatic level calibration experimental model according to claim 5, characterized in that, The micrometer is mounted on the column using bolt-type clamps.

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