Multifunctional fiber grating sensor and working method thereof

Abstract

The invention relates to the technical field of sensors, in particular to a multifunctional fiber bragg grating sensor and a working method thereof, and the multifunctional fiber bragg grating sensor comprises at least two groups of fiber bragg gratings which are respectively used for measuring physical or chemical properties of an object. And the calibration module is used for calibrating the fiber bragg grating, so that the measurement precision of the fiber bragg grating is higher than a preset precision threshold value. And the adaptive adjustment module is used for correcting the physical or chemical performance of the object according to the mutual influence of each group of fiber bragg gratings, so that the error between the measured value and the actual value of the fiber bragg grating sensor is smaller than a preset error threshold value. According to the invention, the self-adaptive adjustment module is arranged, the mutual interference among the performances is fully considered, and then the interference term is eliminated through the correction formula, so that the finally measured and displayed performance value is closer to the actual value, and compared with the existing single-function fiber grating sensor, the fiber grating sensor has higher measurement precision, and the measurement efficiency is effectively improved at the same time.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a multifunctional fiber grating sensor and a working method thereof. Background Art

[0002] Fiber Bragg Grating Sensors (FBG) are sensors based on optical fiber technology that can be used to measure various physical quantities. They have the advantages of high sensitivity and anti-electromagnetic interference. They have been widely used in many industries, such as structural health monitoring, environmental monitoring, medical diagnosis, etc. Although the application of fiber grating sensors has achieved remarkable results, there are still many technical challenges in terms of multifunctionality and mutual interference between functions.

[0003] Existing fiber Bragg grating sensors have the following defects: Lack of versatility: Existing fiber Bragg grating sensors focus on the measurement of a single physical quantity. For example, grating sensors specifically used for temperature measurement or strain measurement are relatively common, but few products can effectively measure multiple physical quantities (such as temperature, pressure, and humidity) at the same time. Mutual interference problem: In a multifunctional sensor, multiple measurement functions may interfere with each other. For example, temperature changes may affect pressure measurements, and humidity changes may affect temperature and strain measurements. This mutual interference will lead to reduced measurement accuracy of the sensor and unreliable results. Data processing complexity: Processing the output data of a multifunctional sensor is usually more complicated, especially in the face of interference. A high level of technology and specialized algorithms are required to extract useful signals. The real-time requirements are contrary to complexity.

[0004] In general, existing fiber grating sensors are affected by mutual interference between functions, and have the defects of insufficient measurement accuracy and low system efficiency in actual measurement. Summary of the invention

[0005] Based on the above objectives, the present invention provides a multifunctional fiber grating sensor and a working method thereof.

[0006] A multifunctional fiber grating sensor comprises at least two groups of fiber gratings, a calibration module and an adaptive adjustment module.

[0007] Each set of fiber Bragg gratings is used to measure the physical or chemical properties of an object;

[0008] The calibration module is used to calibrate the fiber Bragg grating so that the measurement accuracy of the fiber Bragg grating is higher than a preset accuracy threshold;

[0009] The adaptive adjustment module is used to correct the physical or chemical properties of the object according to the mutual influence of each group of the fiber Bragg gratings, so that the error between the measured value of the fiber Bragg grating sensor and the actual value is less than a preset error threshold.

[0010] Optionally, the fiber grating is any two or more combinations of pressure fiber grating, temperature fiber grating, humidity fiber grating, vibration fiber grating, concentration fiber grating, air pressure fiber grating, and pH fiber grating.

[0011] Optionally, the calibration module includes a plurality of calibration units, and the calibration units are used to calibrate the corresponding fiber Bragg gratings according to the performance to be measured, and the calibration process includes:

[0012] The change of the reflection wavelength of the fiber grating is measured under multiple preset performances, and the relationship between the performance and the wavelength change is constructed; the formula is expressed as:

[0013] S=K(λ1-λ0)

[0014] Where P is the calibration value, K is the fiber Bragg grating sensitivity, λ1 is the measured reflection wavelength, and λ0 is the initial reflection wavelength.

[0015] Optionally, the adaptive correction unit includes multiple performance correction units, a first comprehensive correction unit and a second comprehensive correction unit; the performance correction unit is used to correct the measured value of each fiber grating according to the mutual influence between each performance to obtain a first correction formula; the first comprehensive correction unit is used to establish a linear regression relationship formula using multivariable linear regression based on multiple of the first correction formulas, and output a first comprehensive correction value; the second comprehensive correction unit is used to correct the first comprehensive correction value to obtain a second comprehensive correction value when the fluctuation amplitude of the measured value of the fiber grating is greater than a preset amplitude threshold.

[0016] Optionally, the correction formula of the performance correction unit is:

[0017] S i =S mi +∑k i (S aj -S mj

[0018] In the formula, S mi is the first correction value of the i-th performance, k i is the interference coefficient of other performances on the i-th performance, S aj is the first correction value of the jth performance, S mj is the calibration value of the jth performance.

[0019] Optionally, the linear regression relationship formula is expressed as:

[0020] Y=c+∑d i S i

[0021] In the formula, Y is the final output value, c is the intercept, d is i is the regression coefficient of the ith performance, S i is the first correction value of the ith performance.

[0022] Optionally, in the second comprehensive correction unit, the fluctuation value of the interference coefficient is expressed as:

[0023]

[0024] In the formula, K iA is the fluctuation value of the interference coefficient of the i-th performance, K i is the interference coefficient of other performances on the i-th performance, is the average value during the measurement period.

[0025] Optionally, in the second comprehensive correction unit, the corrected regression coefficient is expressed as:

[0026]

[0027] Where Cov is the covariance and Var is the variance.

[0028] Optionally, in the second comprehensive correction unit, the second comprehensive correction formula is expressed as:

[0029] Y2=Yd iA S i

[0030] Wherein, Y2 is the second comprehensive correction value.

[0031] A working method of a multifunctional fiber Bragg grating sensor is implemented by the above-mentioned multifunctional fiber Bragg grating sensor, comprising the following steps:

[0032] Determine the measurement type and measurement environment, and select the corresponding sensor type;

[0033] Calibrate the sensor according to the selected sensor type;

[0034] For each calibrated performance, the measured value is corrected taking into account the mutual interference between the performances; the correction process includes:

[0035] first revision of current performance based on other performance;

[0036] The first comprehensive correction of all properties was performed using multivariable linear regression;

[0037] When the fluctuation amplitude of the measured value is greater than a preset amplitude threshold, a second comprehensive correction is performed according to the fluctuation value of the interference coefficient.

[0038] Beneficial effects of the present invention:

[0039] The multifunctional fiber grating sensor provided by the present invention adopts a combination of multiple groups of fiber gratings, which can not only measure a variety of different physical or chemical properties at the same time, but also effectively improve the measurement accuracy by calibrating each fiber grating to determine the relationship between the wavelength change of the fiber grating and each property. In addition, by setting an adaptive adjustment module, the mutual interference between the various properties is fully considered, and then the interference items are eliminated by the correction formula, so that the performance value displayed by the final measurement is closer to the actual value. Compared with the existing single-function sensor, it has higher measurement accuracy and effectively improves the measurement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 A schematic diagram of the module structure of a multifunctional fiber grating sensor provided in an embodiment of the present invention;

[0042] Figure 2 The present invention provides a flowchart of a working method of a multifunctional fiber grating sensor. DETAILED DESCRIPTION

[0043] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. At the same time, it is explained here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art may also adopt other alternatives to implement some known technologies; and the accompanying drawings are only for more specific description of the embodiments, and are not intended to specifically limit the present invention.

[0044] like Figure 1 As shown, Figure 1 As shown, the multifunctional fiber Bragg grating sensor provided by the embodiment of the present invention includes: at least two groups of fiber Bragg gratings, a calibration module and an adaptive adjustment module.

[0045] Each fiber Bragg grating is used to measure the physical or chemical properties of an object. In this embodiment, three groups of fiber Bragg gratings are used, namely, pressure fiber Bragg grating, temperature fiber Bragg grating and humidity fiber Bragg grating. These three groups of fiber Bragg gratings are used to measure the pressure, temperature and humidity of the object to be measured. Among them, the material of the temperature fiber Bragg grating is selected from materials with good thermal stability and low linear expansion coefficient, such as erbium-doped fiber or specific fiber coating. The material of the pressure fiber Bragg grating is selected from high-strength optical fiber combined with a special pressure-sensitive coating (such as piezoelectric material) to enhance the response. This kind of optical fiber material has the characteristics of strong high-pressure resistance and can maintain good linear response under high pressure. Humidity fiber Bragg gratings usually use standard optical fibers (such as single-mode or multi-mode optical fibers), and the outer periphery is coated with a humidity-sensitive polymer material, such as a polymer coating (such as PVA, PVP, etc.). These materials have a strong affinity for water molecules and can effectively improve the measurement accuracy of humidity fiber Bragg gratings.

[0046] The measurement principle of fiber Bragg grating is as follows: Fiber Bragg grating is a periodically changing refractive index structure in optical fiber, and its basic principle is based on Bragg grating. When a light beam passes through a fiber Bragg grating, light of a specific wavelength will be reflected, while light of other wavelengths will pass through the grating. The reflected wavelength (Bragg wavelength) is related to the refractive index of the optical fiber, the period of the grating, and the external environment.

[0047] The expression of reflection wavelength is:

[0048] λ i =2γf

[0049] In the formula, λ i is the reflection wavelength, γ is the refractive index of the optical fiber, and f is the grating period.

[0050] When the performance to be measured changes, the grating refractive index and period will change, resulting in a shift in the reflected wavelength. Therefore, by measuring the change in reflected wavelength, information about the performance to be measured can be accurately obtained.

[0051] In other embodiments, the number of fiber gratings can be more or less, and the corresponding functions can also be different, for example, using two or more combinations of pressure fiber gratings, temperature fiber gratings, humidity fiber gratings, vibration fiber gratings, concentration fiber gratings, air pressure fiber gratings, etc.

[0052] The calibration module is used to calibrate the fiber Bragg grating so that the measurement accuracy of the fiber Bragg grating is higher than the preset accuracy threshold. The calibration module includes multiple calibration units, which are used to calibrate different properties of the object to be measured. The calibration unit is used to calibrate the corresponding fiber Bragg grating according to the property to be measured, and the calibration process includes:

[0053] The change of the reflected wavelength of the fiber Bragg grating is measured under multiple preset performances, and the relationship between the performance and the wavelength change is established. The formula is expressed as:

[0054] S=K(λ1-λ0)

[0055] Where P is the calibration value, K is the fiber Bragg grating sensitivity, λ1 is the measured reflection wavelength, and λ0 is the initial reflection wavelength.

[0056] Specifically, in this embodiment, a pressure calibration unit, a temperature calibration unit and a humidity calibration unit are provided for the pressure fiber Bragg grating, the temperature fiber Bragg grating and the humidity fiber Bragg grating respectively.

[0057] Among them, the calibration process of the pressure calibration unit includes:

[0058] By measuring the change in reflected wavelength at a known pressure, a relationship between pressure and wavelength change is constructed.

[0059] In this embodiment, a standard pressure generator is used to measure the pressure in a dry vacuum environment. During the measurement, different pressure values ​​are applied to the pressure fiber grating, for example, a constant pressure value is applied: 50, 100, 150, 200, ..., 1000KPa, starting from the lowest pressure, and gradually increasing to the set maximum pressure. Each pressure level is kept fixed for at least 1-2 minutes to ensure that the sensor reading is stable. At each set pressure, the output signal of the optical fiber sensor (such as wavelength change) and the corresponding standard pressure value are recorded. The same pressure level is measured 3 or more times, and the average value is taken to ensure the reliability of the data.

[0060] After analyzing the experimental data, the relationship between pressure and wavelength change is obtained, and the formula is expressed as:

[0061] P = k P (λ1-λ0)

[0062] Where P is the pressure value, k P is the pressure sensitivity, λ1 is the measured reflection wavelength, and λ0 is the initial reflection wavelength.

[0063] The calibration process of the temperature calibration unit includes:

[0064] The sensor is placed in a standard environment with different known temperatures, and its reflected wavelength changes are recorded. Similar to the calibration process of the pressure calibration unit, by setting different constant temperatures, measuring and recording the wavelength changes of the temperature fiber Bragg grating, the relationship between temperature and wavelength is analyzed, and the formula is expressed as:

[0065] ΔT=α(Δλ T -βΔL)

[0066] In the formula, ΔT is the temperature change, α is the temperature sensitivity coefficient, and Δλ is T is the reflection wavelength variable caused by temperature, β is the strain sensitivity coefficient, and ΔL is the strain change.

[0067] The calibration process of the humidity calibration unit includes:

[0068] Create a known humidity environment using a standard humidity source such as sodium chloride solution, potassium chloride solution, or saturated water vapor atmosphere.

[0069] Use a calibrated moisture meter to ensure consistency with sensor measurements.

[0070] Environmental control: Calibration is performed in a constant temperature and humidity environment chamber to control different relative humidity levels, such as 10%, 20%, 30%, ..., 100%.

[0071] Select multiple humidity values ​​for calibration, draw the relationship curve between the sensor output and the actual humidity value, and establish a mathematical model. Specifically, a linear regression model can be used to fit the relationship between the sensor output and the actual humidity. The formula is:

[0072] H m =k m H a +b

[0073] In the formula, H m is the measured humidity value, H a is the actual humidity value, k m is the humidity sensitivity coefficient, and b is the bias.

[0074] Response time calibration: Calculate the response time when relative humidity changes. The formula is:

[0075]

[0076] In the formula, H e is the final ambient humidity, H i is the current measured humidity, H c is the humidity value finally reached by the sensor, k t is the time constant of the sensor.

[0077] The sensitivity coefficient of the final humidity value calibration is calculated through the humidity response time and multiple humidity measurement values ​​through averaging technology.

[0078] The adaptive adjustment module is used to correct the physical or chemical properties of the object according to the mutual influence of each group of fiber Bragg gratings, so that the error between the measured value of the fiber Bragg grating sensor and the actual value is less than the preset error threshold. The adaptive adjustment module includes multiple performance correction units, a first comprehensive correction unit and a second comprehensive correction unit. The performance correction unit is used to correct each performance measurement value according to the mutual influence between each performance. The correction formula of the performance correction unit is:

[0079] S i =S mi +∑k i (S aj -S mj

[0080] In the formula, S mi is the first correction value of the i-th performance, k i is the interference coefficient of other performances on the i-th performance, S aj is the first correction value of the jth performance, S mj is the calibration value of the jth performance.

[0081] In this embodiment, for the pressure fiber Bragg grating, the temperature fiber Bragg grating and the humidity fiber Bragg grating, the performance correction unit includes a pressure correction unit, a temperature correction unit and a humidity correction unit.

[0082] The correction process of the pressure correction unit includes:

[0083] Temperature changes and pressure changes will cause the reflected wavelength of the grating to change. Assuming that the wavelength change caused by temperature is ΔλT and the wavelength change caused by pressure is ΔλP, the total wavelength change can be expressed as the combined effect of temperature change and pressure change, and the formula is expressed as:

[0084] Δλ=Δλ T +Δλ P

[0085] Where Δλ is the total wavelength change.

[0086] In a specific case, according to the ideal relationship between pressure and temperature:

[0087] PV=nRT

[0088] Where P is pressure, V is volume, n is the number of moles of gas, R is the gas constant, and T is temperature (K).

[0089] It can be seen that pressure is directly proportional to temperature.

[0090] Under certain conditions, the effect of temperature on pressure can be compensated by a correction formula, which is expressed as:

[0091] P c =P m +α P (T a -T0)

[0092] Where P c is the corrected pressure value, P m is the measured pressure value, α P is the temperature sensitivity coefficient under pressure, T a is the actual temperature, T0 is the calibration temperature.

[0093] The effect of humidity on pressure can be expressed by the following correction formula:

[0094] P h =P m (1-k mH (H-H0))

[0095] Where P h is the corrected pressure value, k mH is the humidity sensitivity coefficient under pressure, H is the actual humidity, and H0 is the calibrated humidity.

[0096] For example, when measuring the actual pressure, assuming the actual pressure is P a , the pressure calibration value is P m , the actual temperature is T a , the temperature calibration value is T m , the actual humidity is H a , humidity calibration value is H m , then the pressure correction formula, that is, the actual pressure P a It can be expressed as:

[0097] P a =P m +k TP (T a -T m )+k HP (H a -H m )

[0098] In the formula, k TP is the interference coefficient of temperature on pressure, k HP is the interference coefficient of humidity on pressure.

[0099] The temperature correction formula of the temperature correction unit, that is, the actual temperature T a It can be expressed as:

[0100] T a =T m +α PT (P a -Pm )+α HT (H a -H m )

[0101] In the formula, α PT is the interference coefficient of pressure on temperature, α HT is the interference coefficient of humidity on temperature.

[0102] The humidity correction formula of the humidity correction unit, that is, the actual humidity H a It can be expressed as:

[0103] H a =H m +k TH (T a -T m )+k PH 9P a -P m )

[0104] In the formula, k TH is the interference coefficient of temperature on humidity, k PH is the interference coefficient of pressure on humidity.

[0105] In other embodiments, the correction formula of each performance correction unit is adaptively modified for selected fiber gratings with other different performances.

[0106] Specifically, when measuring the gas concentration, the concentration fiber Bragg grating, temperature fiber Bragg grating, humidity fiber Bragg grating and air pressure fiber Bragg grating are selected. First, the concentration fiber Bragg grating and air pressure fiber Bragg grating are calibrated by the calibration module. The corresponding calibration formulas include:

[0107] Construct multiple gas environments with standard concentrations. During the measurement, the concentration fiber Bragg grating is placed in gas environments with different concentrations. For example, the air pressure values ​​are set to 0.2, 0.4, 0.6, 0.8, ..., 2 mol / L. Starting from the lowest air pressure, gradually increase to the set maximum air pressure. Keep each air pressure level fixed for at least 1-2 minutes to ensure that the sensor reading is stable. At each set air pressure, record the output signal (such as wavelength change) of the concentration fiber Bragg grating and the corresponding standard air pressure value. Perform 3 or more measurements at the same air pressure level and take the average value to ensure the reliability of the data. After analyzing the experimental data, the relationship between concentration and wavelength change is obtained, that is, the concentration calibration formula is:

[0108] C=k C (λ1-λ0)

[0109] In the formula, C is the concentration, k C is the concentration sensitivity.

[0110] Construct multiple gas environments with standard concentrations. During the measurement, place the pressure fiber Bragg grating in gas environments with different concentrations. For example, set the pressure values: 5, 10, 15, 20, ..., 100KPa, starting from the lowest pressure, and gradually increase to the set maximum pressure. Keep each pressure level fixed for at least 1-2 minutes to ensure that the sensor reading is stable. At each set pressure, record the output signal of the concentration fiber Bragg grating (such as wavelength change) and the corresponding standard pressure value. Measure the same pressure level 3 or more times and take the average value to ensure the reliability of the data. The pressure calibration formula is:

[0111] P G =k PG (λ1-λ0)

[0112] Where P G is the air pressure, k PG is the air pressure sensitivity.

[0113] Correspondingly, the performance correction unit includes a concentration correction unit, a temperature correction unit, a humidity correction unit and an air pressure correction unit.

[0114] The effect of temperature on concentration is compensated by a correction formula, which is expressed as:

[0115] C c =C m +α TC (T a -T0)

[0116] In the formula, C c is the corrected concentration value, C m is the measured concentration value, α TC is the temperature sensitivity coefficient under concentration, T a is the actual temperature, T0 is the calibration temperature.

[0117] The effect of humidity on concentration can be expressed by the following correction formula:

[0118] C C =C m (1-k HC (H-H0))

[0119] In the formula, k HC is the humidity sensitivity coefficient under concentration, H is the actual humidity, and H0 is the calibrated humidity.

[0120] The effect of air pressure on concentration can be expressed by the following correction formula:

[0121] C c =C m +α PC (P Ga -PG0 )

[0122] In the formula, α TC is the pressure sensitivity coefficient under concentration, P Ga is the actual air pressure, P G0 To calibrate the air pressure.

[0123] The correction formulas for actual pressure, temperature, light intensity and pH are calculated based on the mutual interference coefficients of temperature, humidity, air pressure and concentration.

[0124] For example, when measuring the actual air pressure, assuming that the actual air pressure is P Ga , the pressure calibration value is P Gm , the actual temperature is T a , the temperature calibration value is T m , the actual humidity is H a , humidity calibration value is H m The actual concentration is C a , the concentration calibration value is C m , then the pressure correction formula, that is, the actual pressure P Ga It can be expressed as:

[0125] P Ga =P Gm +α TPG (T a -T m )+α HPG (H a -H m )+α CPG (C a -C m )

[0126] In the formula, α TPG is the interference coefficient of temperature on pressure, α HPG is the interference coefficient of humidity on pressure, α CPG is the interference coefficient of concentration on air pressure.

[0127] The temperature correction formula of the temperature correction unit, that is, the actual temperature T a It can be expressed as:

[0128] T a =T m +α PGT (P Ga -P Gm )+α HT (H a -H m )+α CT (C a -C m )

[0129] In the formula, α PT is the interference coefficient of pressure on temperature, α HT is the interference coefficient of humidity on temperature, α CT is the interference coefficient of concentration on temperature.

[0130] The humidity correction formula of the humidity correction unit, that is, the actual humidity T a It can be expressed as:

[0131] H a =H m +k TH (T a -T m )+k PH (P a -P m )+k CT (C a -C m )

[0132] In the formula, k TH is the interference coefficient of temperature on humidity, k PH is the interference coefficient of pressure on humidity, k CH is the interference coefficient of concentration on humidity.

[0133] The concentration correction formula of the concentration correction unit, that is, the actual concentration C a It can be expressed as:

[0134] C a =C m +α TC (T a -T m )+α HC (H a -H m )+α PGC (P Ga -P Gm )

[0135] In the formula, α TC is the interference coefficient of temperature on concentration, α HC is the interference coefficient of humidity on concentration, α PGC is the interference coefficient of air pressure on concentration.

[0136] The first comprehensive correction unit is used to establish a linear regression relationship formula using multivariable linear regression according to the plurality of the first correction formulas. The linear regression relationship formula is expressed as:

[0137] Y=c+∑d i S i

[0138] In the formula, Y is the output value, c is the intercept, d is thei is the regression coefficient of the ith performance, S i is the first correction value of the ith performance.

[0139] In this embodiment, in order to analyze the overall impact of pressure, temperature and humidity, it is necessary to consider the nonlinear relationship between the three and the dynamic characteristics of the system. This embodiment uses multivariable linear regression to establish a linear regression relationship formula, which is expressed as:

[0140] Y=c+d1P+d2T+d3H

[0141] Where Y is the output value, that is, the first comprehensive correction value, c is the intercept, and d1, d2, and d3 are the regression coefficients of pressure, temperature, and humidity, respectively.

[0142] By solving the equation group consisting of the pressure correction formula, temperature correction formula, humidity correction formula and linear regression relationship formula, the regression coefficients of pressure, temperature and humidity can be calculated respectively.

[0143] The correction process of the second comprehensive correction unit includes: determining whether there is at least one group of fiber gratings whose measurement value fluctuation amplitude is greater than a preset amplitude threshold; if so, calculating the fluctuation value of the interference coefficient based on the corresponding measurement value; and then correcting the regression coefficient based on the fluctuation value; and using the corrected linear regression relationship formula to calculate the second comprehensive correction value.

[0144] The fluctuation range is expressed as:

[0145]

[0146] In the formula, A i is the fluctuation range of the ith performance, S imax is the maximum measured value of the ith performance, S imin is the minimum measured value of the ith performance.

[0147] The fluctuation value of the interference coefficient is expressed as:

[0148]

[0149] In the formula, K iA is the fluctuation value of the interference coefficient of the i-th performance, K i is the interference coefficient of other performances on the i-th performance, is the average value during the measurement period.

[0150] Substitute the fluctuation value of the interference coefficient into the corresponding correction formula and linear regression relationship formula to calculate the corrected regression coefficient d iA The corrected regression coefficient is expressed as:

[0151]

[0152] Where Cov is the covariance and Var is the variance.

[0153] Then the second comprehensive correction formula of the second comprehensive correction unit is expressed as:

[0154] Y2=Yd iA S i

[0155] Wherein, Y2 is the second comprehensive correction value.

[0156] A multifunctional fiber Bragg grating sensor of this embodiment adopts a combination of multiple groups of fiber Bragg gratings, which can not only measure a variety of different physical or chemical properties at the same time, but also effectively improve the measurement accuracy by calibrating each fiber Bragg grating to determine the relationship between the wavelength change of the fiber Bragg grating and each property. In addition, by setting an adaptive adjustment module, the mutual interference between the various properties is fully considered, and then the interference items are eliminated through the correction formula, so that the performance value displayed by the final measurement is closer to the actual value. Compared with the existing single-function sensors, it has higher measurement accuracy and effectively improves the measurement efficiency.

[0157] like Figure 2 As shown, the present invention also protects a working method of a multifunctional fiber grating sensor, which is implemented by the multifunctional fiber grating sensor, comprising the following steps:

[0158] First, determine the measurement type and measurement environment, and select the corresponding sensor type. For example, when measuring pressure, consider the temperature range, humidity, and corrosiveness of the sensor in the working environment, select materials with good resistance to environmental erosion and temperature resistance, and select sensors with pressure fiber Bragg gratings, temperature fiber Bragg gratings, humidity fiber Bragg gratings, and pH fiber Bragg gratings. At the same time, evaluate the required measurement accuracy to ensure that the selected sensor meets the measurement standards.

[0159] According to the specific application requirements, it is also necessary to design the appropriate grating period, length and width to ensure the compatibility of the selected sensor with existing systems or supporting equipment.

[0160] Secondly, the sensor is calibrated according to the selected sensor type. For example, when measuring pressure, a sensor with pressure fiber Bragg grating, temperature fiber Bragg grating, humidity fiber Bragg grating, and pH fiber Bragg grating is selected, and each fiber Bragg grating in the sensor is calibrated separately. The specific calibration method is as described in the above multifunctional fiber Bragg grating sensor.

[0161] Finally, for each calibrated performance, the mutual interference between each performance is considered, and the first comprehensive correction and the second comprehensive correction are performed on the measured value. For example, for a sensor with pressure fiber grating, temperature fiber grating, humidity fiber grating, and pH fiber grating, when measuring pressure, it is necessary to simultaneously consider the influence of temperature, humidity, and pH on pressure, and construct a correction equation group through the mutual influence relationship between pressure, temperature, humidity, and pH, and then calculate the corresponding actual pressure, actual temperature, actual humidity, and actual pH, respectively. It can not only measure a variety of different physical or chemical properties at the same time, but also fully consider the mutual interference between each performance, effectively improving the measurement accuracy and efficiency.

[0162] The present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention. In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without the description of these details. In addition, in order to avoid unnecessary confusion about the essence of the present invention, well-known methods, processes, procedures, components and circuits are not described in detail.

[0163] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A multifunctional fiber Bragg grating sensor, characterized in that: include: At least two groups of fiber Bragg gratings, respectively used to measure the physical or chemical properties of an object; A calibration module, used for calibrating the fiber Bragg grating so that the measurement accuracy of the fiber Bragg grating is higher than a preset accuracy threshold; The adaptive adjustment module is used to correct the physical or chemical properties of the object according to the mutual influence of each group of the fiber Bragg gratings, so that the error between the measured value of the fiber Bragg grating sensor and the actual value is less than a preset error threshold.

2. A multifunctional fiber Bragg grating sensor according to claim 1, characterized in that: The fiber grating is any two or more combinations of pressure fiber grating, temperature fiber grating, humidity fiber grating, vibration fiber grating, concentration fiber grating, air pressure fiber grating, and pH fiber grating.

3. A multifunctional fiber Bragg grating sensor according to claim 1, characterized in that: The calibration module includes a plurality of calibration units, and the calibration units are used to calibrate the corresponding fiber Bragg grating according to the performance to be measured. The calibration process includes: The change of the reflection wavelength of the fiber grating is measured under multiple preset performances, and the relationship between the performance and the wavelength change is constructed; the formula is expressed as: S=K(λ1-λ0) Where P is the calibration value, K is the fiber Bragg grating sensitivity, λ1 is the measured reflection wavelength, and λ0 is the initial reflection wavelength.

4. A multifunctional fiber Bragg grating sensor according to claim 1, characterized in that: The adaptive correction unit includes a plurality of performance correction units, a first comprehensive correction unit and a second comprehensive correction unit; the performance correction unit is used to correct the measured value of each fiber Bragg grating according to the mutual influence between the various performances to obtain a first correction formula; The first comprehensive correction unit is used to establish a linear regression relationship formula using multivariable linear regression according to the plurality of the first correction formulas, and output a first comprehensive correction value; The second comprehensive correction unit is used to correct the first comprehensive correction value to obtain a second comprehensive correction value when the fluctuation amplitude of the measured value of the fiber Bragg grating is greater than a preset amplitude threshold.

5. A multifunctional fiber Bragg grating sensor according to claim 4, characterized in that: The correction formula of the performance correction unit is: S i =S mi +∑k i (S aj -S mj In the formula, S mi is the first correction value of the i-th performance, k i is the interference coefficient of other performances on the i-th performance, S aj is the first correction value of the jth performance, S mj is the calibration value of the jth performance.

6. A multifunctional fiber Bragg grating sensor according to claim 4, characterized in that: The linear regression relationship formula is expressed as: Y=c+∑d i S i In the formula, Y is the final output value, c is the intercept, d is i is the regression coefficient of the ith performance, S i is the first correction value of the ith performance.

7. The multifunctional fiber Bragg grating sensor according to claim 4, characterized in that: In the second comprehensive correction unit, the fluctuation value of the interference coefficient is expressed as: In the formula, K iA is the fluctuation value of the interference coefficient of the i-th performance, K i is the interference coefficient of other performances on the i-th performance, is the average value during the measurement period.

8. The multifunctional fiber Bragg grating sensor according to claim 4, characterized in that: In the second comprehensive correction unit, the corrected regression coefficient is expressed as: Where Cov is the covariance and Var is the variance.

9. The multifunctional fiber Bragg grating sensor according to claim 4, characterized in that: In the second comprehensive correction unit, the second comprehensive correction formula is expressed as: Y2=Yd iA S i Wherein, Y2 is the second comprehensive correction value.

10. A working method of a multifunctional fiber Bragg grating sensor, implemented by a multifunctional fiber Bragg grating sensor according to any one of claims 1 to 9, characterized in that: The following steps are involved: Determine the measurement type and measurement environment, and select the corresponding sensor type; Calibrate the sensor according to the selected sensor type; For each calibrated performance, the measured value is corrected by considering the mutual interference between the performances; The correction process includes: first revision of current performance based on other performance; The first comprehensive correction of all properties was performed using multivariable linear regression; When the fluctuation amplitude of the measured value is greater than a preset amplitude threshold, a second comprehensive correction is performed according to the fluctuation value of the interference coefficient.

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