CN110133324B - Differential type fiber bragg grating acceleration sensing device - Google Patents
Differential type fiber bragg grating acceleration sensing device Download PDFInfo
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- CN110133324B CN110133324B CN201910486077.7A CN201910486077A CN110133324B CN 110133324 B CN110133324 B CN 110133324B CN 201910486077 A CN201910486077 A CN 201910486077A CN 110133324 B CN110133324 B CN 110133324B
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- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
- G01P15/093—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by photoelectric pick-up
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Abstract
The invention discloses a differential fiber bragg grating acceleration sensing device which comprises a base, a shell, a broadband light source, a scanning F-P filter, a photoelectric receiver, a demodulator and a controller, wherein the base and the shell form a sealed cavity; the base on be provided with the stand, the top level of stand is fixed and is provided with the elastic arm, and the free end of elastic arm is fixed and is provided with the quality piece, still is provided with fiber grating, diffuse reflection absorber and fiber interface, diffuse reflection absorber is fixed to be set up in fiber grating's one end, the fiber grating other end and fiber interface fixed connection. The invention takes the rectangular acetal copolymer sheet as the elastic beam, and the differential acceleration measuring light path composed of three fiber gratings with different grating pitches is arranged on a certain position of the elastic beam structure, thereby measuring the acceleration of the component to be measured, and the measurement has the characteristics of self-compensation of temperature error, high sensitivity, good dynamic response, electromagnetic interference resistance and non-invasion to local electromagnetic environment.
Description
Technical Field
The invention relates to the technical field of motion state detection, in particular to a differential fiber bragg grating acceleration sensing device.
Background
Currently, an acceleration sensor is a sensor capable of measuring parameters such as force and displacement associated with acceleration. The traditional acceleration sensor consists of a mass block, a damper, an elastic element, a sensitive element, an adaptive circuit and the like, and in the acceleration process, the acceleration value is obtained by measuring the inertial force borne by the mass block and utilizing Newton's second law. Common acceleration sensors include capacitive, inductive, strain, piezoresistive, piezoelectric, and in recent years MEMS acceleration sensors based on micro-electromechanical technology, etc., depending on the sensor sensitive element.
These acceleration sensors are susceptible to electromagnetic field in the surrounding space of the measuring environment, crosstalk between signal lines and interference caused by long signal ground resistance, which results in distortion or distortion of the transmitted vibration signal. Meanwhile, parasitic harmonic waves can be generated due to improper interconnection among the output connector, the cable connector and the cable of the accelerometer and are superposed in the vibration signals, so that the verification accuracy is influenced. In addition, in some occasions requiring accurate detection of electromagnetic field parameters, monitoring of high-voltage power transmission and distribution equipment, and the like, the use of the acceleration sensors causes invasive damage to the electromagnetic environment, reduction of the insulation performance of the high-voltage equipment, and other adverse effects, so that the use of the traditional sensors is limited.
The fiber grating sensor has obvious advantages in the aspects of electromagnetic interference resistance, no electromagnetic environment invasive damage, high sensitivity, small size, light weight, low cost, high temperature, corrosion environment adaptability and the like compared with a common sensor, and also has the unique advantages of strong intrinsic self-coherence capability and realization of multi-point multiplexing and multi-parameter distributed measurement on one optical fiber by utilizing a multiplexing technology.
The fiber grating sensing system mainly comprises a broadband light source, a fiber grating sensor, a signal demodulation system and the like, wherein the broadband light source provides light energy for the system, the fiber grating sensor senses external measured information by utilizing light waves of the light source, and the external measured information is reflected in real time through the signal demodulation system. The trend in the development of fiber grating sensing systems is to optimize the measurement method, and the optimization of fiber grating sensing systems is mainly considered from three aspects, namely, the light source, the fiber grating sensor and the signal demodulation.
For the optimization of the sensing system, different light sources, sensing structures and sensor demodulation systems are configured according to the number and configuration of the sensors, the sensitivity of the sensors and the resolution of the demodulation system and the actual measurement requirements, so that the cost is low, the measurement error is small and the measurement precision is high. Aiming at the requirement of networking of a future fiber grating sensing system, a light source with good stability, broadband and high output power is used. The fiber grating sensor can realize direct measurement of physical quantities such as temperature, strain and the like.
The wavelength of the fiber grating is sensitive to temperature and strain at the same time, namely the temperature and the strain simultaneously cause the coupling wavelength of the fiber grating to move, so that the temperature and the strain cannot be distinguished by measuring the coupling wavelength movement of the fiber grating. Therefore, the problem of cross sensitivity is solved, and the realization of the differential measurement of temperature and stress is the premise of the practical application of the sensor. The stress and the temperature change are measured by a certain technology to realize the measurement of distinguishing the temperature from the stress, or the influence of the temperature change is eliminated while the stress is measured, which is the key of the feasibility of the technical scheme. Therefore, a practical signal demodulation scheme must have extremely high wavelength resolution. Secondly, the problem of detecting dynamic and static signals is solved, especially the detection of the combinability of the two becomes a difficult point in the practical demodulation technology of grating sensing.
Disclosure of Invention
The invention aims to provide a differential fiber bragg grating acceleration sensing device, which can be constructed by taking an optical grating as a sensitive element and an elastic beam structure, and has the characteristics of temperature error self-compensation, high sensitivity, good dynamic response, electromagnetic interference resistance and non-invasion to local electromagnetic environment in measurement.
The technical scheme adopted by the invention is as follows:
a differential fiber grating acceleration sensing device comprises a base, a shell, a broadband light source, a scanning F-P filter, a photoelectric receiver, a demodulator and a controller, wherein the base and the shell form a sealed cavity;
the base is provided with a stand column, the top end of the stand column is horizontally and fixedly provided with an elastic arm, the free end of the elastic arm is fixedly provided with a mass block, the base is also provided with a fiber grating, a diffuse reflection absorber and an optical fiber interface, the diffuse reflection absorber is fixedly arranged at one end of the fiber grating, and the other end of the fiber grating is fixedly connected with the optical fiber interface;
the optical fiber interface is connected with the left port of the coupler through a conducting optical fiber, the right port of the coupler is connected with a broadband light source through a conducting grating, the downlink port of the coupler is connected with the input port of the scanning F-P filter through the conducting grating, the output light beam of the scanning F-P filter irradiates the photoelectric receiver, the output of the photoelectric receiver is connected with the input end of the demodulator, the output end of the demodulator is connected with the input end of the controller, and the output end of the controller is connected with the control input end of the scanning F-P filter;
one end of the fiber bragg grating provided with the diffuse reflection absorber is arranged on the upper end face of the elastic arm, and the other end of the fiber bragg grating bypasses the mass block, the lower end face of the elastic arm, the vertical surface of the upright post and the upper end face of the base in sequence to be connected with the optical fiber interface; the fiber grating is provided with a first grating, a second grating and a third grating with different pitches, the front section part of the fiber grating containing the first grating is arranged on the upper end face part of the elastic arm, and the optical fiber with the long first grating section is fixedly arranged on the upper end face part of the elastic arm in an adhering manner; the fiber grating middle section part containing the second grating is arranged on the part of the lower end face of the elastic arm, and the optical fiber with the length of the second grating section is fixedly arranged on the part of the lower end face of the elastic arm in an adhering manner, so that the positions of the first grating and the second grating along the length direction of the elastic arm beam are consistent; the fiber grating rear section part containing the third grating is arranged on the part of the side end face of the upright post;
the buffer ring structure is arranged on the part between the second grating and the third grating on the fiber grating, namely the fiber grating of the part is automatically wound to form an annular structure, so that the fiber grating is prevented from being damaged when the elastic arm deforms and swings up and down.
The first grating and the second grating are arranged oppositely and aligned up and down corresponding to the elastic arm, and the positions of the first grating and the second grating are kept consistent along the horizontal direction of the elastic arm.
The elastic arm is of a plate-shaped isosceles trapezoid structure, the long edge of the isosceles trapezoid structure is the bottom, and the bottom of the isosceles trapezoid structure is fixedly connected with the stand column.
The elastic arm is made of acetal copolymer.
The mass block is a plastic mass block.
The fiber grating fixing device also comprises a plastic fixing buckle used for fixing the fiber grating to the bottoms of the upright post and the base.
The base, the upright post and the shell are all made of materials without metal and magnetic conductive components.
The fiber bragg grating fixing device further comprises a fixing part used for fixing the fiber bragg grating to shake left and right.
The fixing part is a limiting groove which is formed in the mass block and extends along the circumferential direction, and the width of the limiting groove is the same as the diameter of the grating.
The bottom of the plastic base is provided with a threaded hole for convenient connection and fixation with a tested body.
The invention takes engineering plastics as manufacturing materials of a base and a shell, takes a rectangular acetal copolymer sheet as an elastic beam, one end of the rectangular acetal copolymer sheet is fixed on a vertical upright post of the base, and the other end of the rectangular acetal copolymer sheet is fixed with a cylindrical inertia mass block to form an elastic beam structure; the fiber bragg grating with three different grating pitches is arranged at a certain position of the elastic beam structure; when in measurement, due to the action of the inertia mass block, the acetal copolymer sheet elastic beam generates corresponding upwarp and downwarp deformation along with the vibration acceleration, the grating 2 is compressed when the grating 1 is stretched, or the grating 2 is stretched when the grating 1 is compressed, so that the grating pitch is changed, and the peak wavelength of reflected light is changed to generate corresponding offset delta lambda1And Δ λ2The grating 3 being unstressed, i.e. Delta lambda30; the grating 1 and the grating 2 form a differential acceleration measuring light path and have a temperature self-compensation function, the reflected light intensity of the grating 3 is used for correcting the influence of the instability of a light source of a measuring system on measurement, so that the acceleration of a component to be measured can be measured, and the measurement has the characteristics of temperature error self-compensation, high sensitivity, good dynamic response, electromagnetic interference resistance and non-invasion to a local electromagnetic environment.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic view of the elastic arm according to the present invention;
FIG. 3 is a schematic structural diagram of the fiber grating according to the present invention;
FIG. 4 shows the spectrum of the light source, reflected light and transmitted light in the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.
As shown in fig. 1, 2 and 3, the present invention comprises a base 7 and a housing 1, which form a sealed cavity, and further comprises a broadband light source 10, a scanning F-P filter 11, a photoelectric receiver 12, a demodulator 13 and a controller 14;
the base 7 is provided with a stand column, the top end of the stand column is horizontally and fixedly provided with an elastic arm 2, the free end of the elastic arm 2 is fixedly provided with a mass block 4, the base is also provided with a fiber grating 3, a diffuse reflection absorber 301 and an optical fiber interface 6, the diffuse reflection absorber 301 is fixedly arranged at one end of the fiber grating 3, and the other end of the fiber grating 3 is fixedly connected with the optical fiber interface 6;
the optical fiber interface 6 is connected with a left port of a coupler 8 through a conducting optical fiber 9, a right port of the coupler 8 is connected with a broadband light source 10 through a conducting grating 9, a downlink port of the coupler 8 is connected with an input port of a scanning F-P filter 11 through the conducting grating 9, an output light beam of the scanning F-P filter 11 irradiates on a photoelectric receiver 12, the output of the photoelectric receiver 12 is connected with the input end of a demodulator 13, the output end of the demodulator 13 is connected with the input end of a controller 14, and the output end of the controller 14 is connected with the control input end of the scanning F-P filter 11;
one end of the fiber bragg grating 3, which is provided with the diffuse reflection absorber 301, is arranged on the upper end face of the elastic arm 2, and the other end of the fiber bragg grating bypasses the mass block 4, the lower end face of the elastic arm 2, the vertical surface of the upright post and the upper end face of the base 7 in sequence and is connected with the optical fiber interface 6; the fiber grating 3 is provided with a first grating 302, a second grating 303 and a third grating 305 with different pitches, the front section part of the fiber grating 3 containing the first grating 302 is arranged on the upper end surface part of the elastic arm 2, and the optical fiber with the length of the first grating 302 section is fixedly arranged on the upper end surface part of the elastic arm 2 in an adhering manner; the middle section part of the fiber grating 3 containing the second grating 303 is arranged on the part of the lower end face of the elastic arm 2, and the optical fiber with the length of the second grating 303 is fixedly arranged on the part of the lower end face of the elastic arm 2 in an adhering manner, so that the positions of the first grating and the second grating along the length direction of the elastic arm beam 2 are consistent; the fiber grating 3 back-end portion including the third grating 305 is provided on a portion of the pillar-side end face;
as shown in fig. 2, the diffuse reflection absorber completely absorbs the light after transmitting the first grating 302 to avoid the influence of re-reflection on the measurement. In actual operation, light beams emitted by the wide-spectrum light source sequentially reflect light beams with different peak spectral lines through the third grating 305, the second grating 303 and the first grating 302, and finally transmit the first grating 302 to enter the diffuse reflection absorber 301, where the light source spectrum, the reflection spectrum and the transmission spectrum are shown in fig. 4.
A buffer ring 304 structure is arranged on the fiber bragg grating between the second grating 303 and the third grating 305, that is, the fiber bragg grating of the buffer ring is wound by itself to form a ring structure, so as to prevent the fiber bragg grating 3 from being damaged when swinging up and down when the elastic arm 2 deforms; the first grating 302 and the second grating 303 are arranged opposite to the elastic arm 2 and aligned up and down, and keep consistent positions along the horizontal direction of the elastic arm 2;
the elastic arm 2 is of a plate-shaped isosceles trapezoid structure, the long edge of the isosceles trapezoid structure is the bottom, and the bottom is horizontally and fixedly connected with the stand column. The elastic arm 2 is made of acetal copolymer, and the acetal copolymer Celcon M90 is made of high polymer materials which can be used for manufacturing special plastic springs, so that the elastic arm not only can meet the requirements of being used as an elastic beam, but also can well avoid the conductivity and magnetic permeability brought by metal substances.
As shown in fig. 3, the elasticity of the acetal copolymer may also be a special elastic beam, when the requirement that the change of the section bending modulus W along the length direction of the beam is in direct proportion to the change of the bending moment M, that is, the condition of formula (1) is met, temperature self-compensation can be realized as long as the positions of the first grating and the second grating in the length direction of the beam are ensured to be consistent, and the specific position in the length direction of the beam of the elastic beam does not affect the measurement structure. The specific elastic beam structure is shown in fig. 3, and the axial strain of the elastic beam is the same at each point along the axis of the elastic beam, so the acting force F can be calculated by the formula (2).
Where σ is the stress, F is the concentration force acting on the free end, L is the beam length, b0The width of the fixed end of the beam and the thickness of the beam are h.
Where ε is the axial strain of the beam, E is the elastic strain of the beam material, and k is a known constant when the structure is determined.
The base, the upright post and the shell are all made of materials without metal and magnetic conduction components. The mass block is a plastic mass block. The fiber grating fixing device also comprises a plastic fixing buckle used for fixing the fiber grating to the bottoms of the upright post and the base.
The fiber bragg grating fixing device further comprises a fixing part used for fixing the fiber bragg grating to shake left and right. The fixing part is a limiting groove which is formed in the mass block and extends along the circumferential direction, and the width of the limiting groove is the same as the diameter of the grating optical fiber. The fixed part is set to prevent the reduction of measurement precision caused by left-right shaking, namely the elastic beam meets the condition that the change of the bending modulus of the section along the length direction of the beam is in direct proportion to the change of the bending moment, and the first grating and the second grating are consistent in position along the length direction of the beam, and the specific position in the length direction of the beam does not influence the measurement structure.
All materials, devices and connecting and fixing processes of the sensing device are free of metal and magnetic conduction component materials, one elastic end of the acetal copolymer is horizontally bonded on the side surface of the upper part of the upright post of the plastic base, the other end of the acetal copolymer is bonded with the plastic mass block, the front section of the fiber bragg grating comprises a first grating part which is bonded on the elastic upper surface of the acetal copolymer in parallel, a subsequent fiber bragg grating is arranged on the elastic lower surface of the acetal copolymer in a turning-back manner after passing through a plastic mass block guide groove along the elastic upper surface of the acetal copolymer, a second grating part which is bonded on the elastic lower surface of the acetal copolymer in parallel is arranged in the middle section of the fiber bragg grating, then the optical fiber is wound into a circular buffer ring at the right angle of the elasticity of the acetal copolymer and the upright post of the plastic base, is fixed along the upright post and the surface of the base through a plastic fixing buckle and is led into an optical fiber interface, the bottom of the plastic base is provided with a threaded hole which is convenient for connecting and fixing with a detected body, plastic housings are used for protection and packaging of devices.
Engineering plastics are used as manufacturing materials of the base and the shell, an acetal copolymer sheet is particularly selected as an elastic beam, one end of the elastic beam is fixed on a vertical upright post of the base, and the other end of the elastic beam is fixed with a cylindrical inertial mass block to form an elastic beam structure; the fiber grating comprises three gratings with different grating pitches, and the pitch of each grating is specially calculated and designed; the front section of the fiber grating comprises a first grating and is adhered and solidified on the upper surface of the acetal copolymer sheet elastic beam, then the fiber grating bypasses a cylindrical inertia mass block, the fiber grating is guided to the lower surface of the acetal copolymer sheet elastic beam through a fiber grating guide groove on the cylindrical inertia mass block, the middle section of the fiber grating comprising a second grating is adhered and solidified on the lower surface of the acetal copolymer sheet elastic beam, then the fiber grating is wound to form a circular buffer ring, the rear section of the fiber grating comprising a third grating is fixed on the surface of the base column through a fixing buckle along the surface of the base column, and finally the output end of the fiber grating is connected with an optical fiber interface.
The differential acceleration sensing device is characterized by self-compensation of temperature error, high sensitivity, good dynamic response, anti-electromagnetic interference and non-invasion to local electromagnetic environment, is applied to monitoring of force, speed, acceleration, vibration and the like, and is particularly suitable for application in complex and strong electromagnetic environment.
The reflection peak wavelengths of the first grating, the second grating and the third grating are different, and the diffuse reflection absorber completely absorbs the light transmitted by the first grating so as to avoid influence on measurement caused by re-reflection.
The differential acceleration measurement sensitive link is formed by the first grating and the second grating, differential measurement of acceleration parameters is realized, and the differential acceleration measurement sensitive link has a temperature self-compensation function; by arranging the third grating as a light source intensity real-time monitoring and correcting element, the influence of unstable light source luminous intensity is eliminated, and the dynamic response characteristic and the measurement precision of the measuring device are improved. According to the relative acceleration a of the inertial massmThe acceleration of the measured vibration body can be obtained by calculating or looking up a table according to the corresponding relation of the acceleration a of the measured vibration body.
The working principle of the invention is specifically described as follows:
as shown in FIG. 1, a light beam emitted by a broadband light source and containing certain spectral components is guided into the optical fiber interface of the device of the present invention through a transmitting optical fiber, a coupler and the transmitting optical fiber, and the incident light beam generates a period T corresponding to a third grating when passing through a third grating in the transmission process of the fiber grating3Has a peak wavelength of λ3The reflected spectrum is received by the photoelectric receiver via the optical fiber interface, the conducting optical fiber, the coupler and the scanning F-P filter, and the peak wavelength lambda is demodulated by the demodulator3And peak light intensity I3(ii) a The transmitted beam passing through the third grating continues to be transmitted along the fiber grating and passes through the second gratingWhen two gratings are formed, a corresponding second grating period T is generated2Has a peak wavelength of λ2The reflected spectrum is received by the photoelectric receiver through a third grating, an optical fiber interface, a conducting optical fiber, a coupler and a scanning F-P filter and is demodulated to obtain a peak wavelength lambda through a demodulator2And peak light intensity I2(ii) a The transmitted beam passing through the second grating is transmitted along the fiber grating, and generates a period T corresponding to the first grating when passing through the first grating1Has a peak wavelength of λ1The reflected spectrum is received by the photoelectric receiver through the second grating, the third grating, the optical fiber interface, the conducting optical fiber, the coupler and the scanning F-P filter, and the peak wavelength lambda is demodulated through the demodulator1And peak light intensity I1The transmission spectrum after passing through the first grating does not contain the peak wavelength lambda1Peak wavelength of λ2Peak wavelength of λ3Finally, the components of (a) are completely absorbed by the diffuse reflection absorber without reflection. The broadband light source spectrum is shown in fig. 4 (a), the reflection spectrum of each grating is shown in fig. 4 (b), and the transmission spectrum after passing through the first grating is shown in fig. 4 (c).
Before measurement, the system is calibrated by using a standard light source with the intensity of the standard light source as IStandard of meritThe reflection peak light intensity of the third grating is IBActually measuring the reflection peak light intensity of the third grating obtained corresponding to the real-time light source as I3The corrected light intensity of the light source is ILight source＝I3·IStandard of merit/IBTherefore, the influence of unstable luminous intensity of the light source is eliminated, and the corrected value is used as an important parameter of the controller for controlling the scanning F-P filter, so that the dynamic response characteristic of the measuring system is improved, and the measuring precision is improved.
The first grating and the second grating form a differential acceleration measurement sensitive link to realize differential measurement of acceleration, and the third grating is used as a light source intensity real-time monitoring and correcting element to eliminate the influence of unstable light source luminous intensity and improve the dynamic response characteristic and measurement precision of the measuring device.
According to the relation between the wavelength of the fiber grating and the change of the strain and the relation between the acceleration and the strain in the elastic system: the specific expression is as follows:
where λ is the grating reflection peak wavelength, Δ λ is the peak wavelength offset, PeIs the elasto-optic coefficient of the fiber, and ε is the strain of the grating.
During measurement, due to the action of the acceleration of the inertia mass block, the first grating and the second grating are stressed, the third grating is not stressed, the first grating and the second grating are stressed by stretching or compressing force and temperature change, so that the grating pitch is changed, and the corresponding reflection peak wavelength generates delta lambda1And Δ λ2The offset is represented by the formulae (1) to (3)
Since it is a differential structure, can be set to epsilon1If ε is determined2＝-ε1-epsilon; the strain generated by the temperature influence is in the same temperature field, and the first grating and the second grating are respectively adhered and fixed with the upper surface and the lower surface of the acetal copolymer elastic beam, so that the temperature strain of the two gratings is the same, namely, the two gratings have epsilon1t＝ε2tThen has the following formula
After finishing, the product is obtained
(7) The equation shows that the differential measurement eliminates the temperature influencing factor. The relative acceleration of the inertia mass block m can be obtained according to the mechanics theorem
Finally, according to the relative acceleration a of the inertial massmAnd calculating or looking up a table according to the corresponding relation of the absolute acceleration a of the measured vibration body to obtain the acceleration a of the measured vibration body.
The preferred embodiments of the present invention will be described in detail below; it should be understood that the preferred embodiments are for purposes of illustration only and are not intended to limit the scope of the present invention.
When the invention is manufactured, the structure design is carried out as follows:
determining a manufacturing material. The elastic beam is made of an acetal copolymer material Celcon M90, and the inertial mass block is made of engineering plastics.
② determining the beam dimension. The structural dimensions meeting the equal strength requirements are adopted, and the specific parameters are shown in table 1.
And thirdly, a bonding process. The epoxy resin is adopted for bonding and curing, and the specific model is LEAFOP/Lantian-9005.
TABLE 1 Beam Structure dimensional parameters
| E/GPa | L/mm | b0/m | h/m | m/g |
| 230 | 50 | 15 | 1 | 40 |
Fiber grating design
Determining a manufacturing material. Pure quartz optical fiber, the coating layer of the optical fiber is polymethyl methacrylate (PMMA)
Determining grating parameters. The fiber grating parameters are shown in table 2.
And thirdly, a manufacturing process. Directly passing through the optical fiber coating layer (acrylate, polyimide, silica gel, carbon, organic modified ceramic) to etch the grating.
TABLE 2 fiber Grating parameters
| Pe | λ1/nm | λ2/nm | λ3/nm | FWHM/nm |
| 0.22 | 1500 | 1550 | 1600 | 6 |
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. The utility model provides a differential formula fiber grating acceleration sensing device, includes base and shell, and the two constitutes sealed cavity, its characterized in that: the system also comprises a broadband light source, a scanning F-P filter, a photoelectric receiver, a demodulator and a controller;
the base is provided with a stand column, the top end of the stand column is horizontally and fixedly provided with an elastic arm, the free end of the elastic arm is fixedly provided with a mass block, the base is also provided with a fiber grating, a diffuse reflection absorber and an optical fiber interface, the diffuse reflection absorber is fixedly arranged at one end of the fiber grating, and the other end of the fiber grating is fixedly connected with the optical fiber interface;
the optical fiber interface is connected with the left port of the coupler through a conducting optical fiber, the right port of the coupler is connected with a broadband light source through a conducting optical fiber, the downlink port of the coupler is connected with the input port of the scanning F-P filter through a conducting optical fiber, the output light beam of the scanning F-P filter irradiates the photoelectric receiver, the output of the photoelectric receiver is connected with the input end of the demodulator, the output end of the demodulator is connected with the input end of the controller, and the output end of the controller is connected with the control input end of the scanning F-P filter;
one end of the fiber bragg grating provided with the diffuse reflection absorber is arranged on the upper end face of the elastic arm, and the other end of the fiber bragg grating bypasses the mass block, the lower end face of the elastic arm, the vertical surface of the upright post and the upper end face of the base in sequence to be connected with the optical fiber interface; the fiber grating is provided with a first grating, a second grating and a third grating with different pitches, the front section part of the fiber grating containing the first grating is arranged on the upper end face part of the elastic arm, and the optical fiber on the first grating section is fixedly arranged on the upper end face part of the elastic arm in an adhering manner; the fiber grating middle section part containing the second grating is arranged on the part of the lower end face of the elastic arm, and the optical fiber on the second grating section is fixedly adhered to the part of the lower end face of the elastic arm, so that the first grating and the second grating are ensured to be consistent in position along the length direction of the elastic arm; the fiber grating rear section part containing the third grating is arranged on the part of the side end face of the upright post;
the buffer ring structure is arranged on the part between the second grating and the third grating on the fiber grating, namely the fiber grating of the part is automatically wound to form an annular structure, so that the fiber grating is prevented from being damaged when the elastic arm deforms and swings up and down.
2. The differential fiber grating acceleration sensing device of claim 1, wherein: the first grating and the second grating are arranged oppositely and aligned up and down corresponding to the elastic arm, and the positions of the first grating and the second grating are kept consistent along the horizontal direction of the elastic arm.
3. The differential fiber grating acceleration sensing device of claim 1, wherein: the elastic arm is of a plate-shaped isosceles trapezoid structure, the long edge of the isosceles trapezoid structure is the bottom, and the bottom of the isosceles trapezoid structure is fixedly connected with the stand column.
4. The differential fiber grating acceleration sensing device according to claim 1, characterized in that: the elastic arm is made of acetal copolymer.
5. The differential fiber grating acceleration sensing device of claim 1, wherein: the mass block is a plastic mass block.
6. The differential fiber grating acceleration sensing device of claim 1, wherein: the fiber grating fixing device also comprises a plastic fixing buckle used for fixing the fiber grating to the bottoms of the upright post and the base.
7. The differential fiber grating acceleration sensing device of claim 1, wherein: the base, the upright post and the shell are all made of materials without metal and magnetic conductive components.
8. The differential fiber grating acceleration sensing device of claim 1, wherein: the fiber bragg grating fixing device further comprises a fixing part for preventing the fiber bragg grating from shaking left and right.
9. The differential fiber grating acceleration sensing device of claim 8, wherein: the fixing part is a limiting groove which is formed in the mass block and extends along the circumferential direction, and the width of the limiting groove is the same as the diameter of the grating.
10. The differential fiber grating acceleration sensing device of claim 1, wherein: the bottom of the base is provided with a threaded hole for convenient connection and fixation with a tested body.
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| WO2021143742A1 (en) * | 2020-01-13 | 2021-07-22 | 奥动新能源汽车科技有限公司 | Swing sensor |
| CN111879970B (en) * | 2020-08-31 | 2022-06-24 | 防灾科技学院 | Temperature insensitive FBG acceleration sensor and method based on strain chirp effect |
| CN112683177B (en) * | 2020-12-02 | 2023-04-11 | 浙江煤炭测绘院有限公司 | Tunnel construction lining and ballast bed relative displacement monitoring devices |
| CN114061731A (en) * | 2021-09-27 | 2022-02-18 | 北京自动化控制设备研究所 | Non-magnetic interference type optical fiber vector hydrophone |
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