CN105203202B - Optical fiber raster vibration displacement sensor - Google Patents
Optical fiber raster vibration displacement sensor Download PDFInfo
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- CN105203202B CN105203202B CN201510748195.2A CN201510748195A CN105203202B CN 105203202 B CN105203202 B CN 105203202B CN 201510748195 A CN201510748195 A CN 201510748195A CN 105203202 B CN105203202 B CN 105203202B
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- fiber grating
- vibration displacement
- displacement sensor
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- diaphragm
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- 238000006073 displacement reaction Methods 0.000 title claims abstract description 56
- 239000013307 optical fiber Substances 0.000 title abstract description 5
- 239000000835 fiber Substances 0.000 claims abstract description 70
- 230000035945 sensitivity Effects 0.000 claims description 7
- 230000001133 acceleration Effects 0.000 description 4
- 239000012528 membrane Substances 0.000 description 4
- 230000010354 integration Effects 0.000 description 3
- 238000012544 monitoring process Methods 0.000 description 3
- 238000004026 adhesive bonding Methods 0.000 description 2
- 230000003321 amplification Effects 0.000 description 2
- 229920006332 epoxy adhesive Polymers 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
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- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
A kind of optical fiber raster vibration displacement sensor, which is characterized in that the optical fiber raster vibration displacement sensor includes：The hollow shell surrounded by preceding facade, rear facade, left facade, right facade, top and bottom；The shaft being installed on the preceding facade and rear facade of shell, shaft is relative to shell freedom to pivot；The diaphragm for being fixed on bottom surface and extending vertically upwards；The inner end of wind spring is fixed on the front of shaft, and the outer end of wind spring and the top of diaphragm connect, and the other end of diaphragm is fixed on the bottom surface of shell；It is fixedly installed cantilever beam at the rear portion of shaft, cantilever beam left part is fixedly connected with shaft, and the right end of cantilever beam is fixedly connected with mass block；One end of horizontally disposed fiber grating is fixedly connected with diaphragm top, and the other end passes through the hole on the left facade of shell, and is fixedly connected in Kong Zhongyu shells.
Description
Technical Field
The invention relates to the technical field of optical fiber sensors, in particular to an optical fiber grating vibration sensor for directly measuring vibration displacement.
Background
The fiber bragg grating vibration sensor is a sensor which utilizes an external signal to modulate a fiber bragg grating to cause strain in the fiber bragg grating to change, thereby causing the central wavelength of reflected light to change and detecting an external weak vibration signal by detecting the change of the central wavelength. Compared with the conventional electromagnetic sensor, the fiber grating vibration sensor has obvious advantages in the aspects of sensitivity, large dynamic range, reliability, multiplexing capability and the like, can be applied to the fields of vibration monitoring, earthquake monitoring, vibration security and the like of equipment, and becomes an important direction for the development of high-performance vibration sensors.
In a conventional fiber grating vibration sensor, the acceleration of vibration is mainly measured, but in some applications, the displacement of vibration needs to be measured. The displacement of vibration is measured by a conventional fiber grating vibration sensor, and is generally obtained by twice integrating the acceleration. However, the displacement is obtained by measuring the secondary integral through acceleration, on one hand, the integral operation can amplify low-frequency interference and cause larger errors, particularly, the fiber grating sensor is sensitive to low-frequency environment and temperature change and is easy to introduce low-frequency environment noise, the performance of the sensor is seriously affected by the low-frequency noise through integral amplification, on the other hand, the integral operation increases the signal processing burden of the system, and for real-time signal monitoring, a back-end system is required to have stronger processing capacity, so that the real-time integral operation is realized.
Therefore, it is necessary to design a fiber grating displacement vibration sensor for directly measuring the displacement of vibration to solve the above practical application problems.
Disclosure of Invention
The invention mainly aims to provide a fiber bragg grating vibration displacement sensor which can directly measure the displacement of a vibration signal.
In order to achieve the purpose, the technical scheme of the invention is realized as follows: a fiber grating vibration displacement sensor, comprising: the hollow shell is formed by a front vertical surface, a rear vertical surface, a left vertical surface, a right vertical surface, a top surface and a bottom surface in a surrounding mode; the rotating shafts are arranged on the front vertical surface and the rear vertical surface of the shell and can freely pivot relative to the shell; a diaphragm fixed on the bottom surface and extending vertically upwards; the inner end of the coil spring is fixed at the front part of the rotating shaft, the outer end of the coil spring is connected with the top end of the diaphragm, and the other end of the diaphragm is fixed on the bottom surface of the shell; the rear part of the rotating shaft is fixedly provided with a cantilever beam, the left part of the cantilever beam is fixedly connected with the rotating shaft, and the right end of the cantilever beam is fixedly connected with a mass block; the mass is used for picking up vibration signals. One end of the fiber bragg grating which is horizontally arranged is fixedly connected with the upper part of the diaphragm, and the other end of the fiber bragg grating penetrates through a hole in the left vertical surface of the shell and is fixedly connected with the shell in the hole for measuring a vibration signal.
The scheme is characterized in that the fiber grating is perpendicular to the membrane, and certain initial pretension force is applied to the fiber grating.
And a certain prestress exists in the coil spring, so that an elastic system formed by the mass block and the coil spring is in a balance position when the sensor is vertically placed.
The fiber grating vibration displacement sensor changes the resonance frequency of the fiber grating vibration displacement sensor by adjusting the mass of the mass block, and changes the sensitivity and the resonance frequency of the fiber grating vibration displacement sensor by adjusting the elasticity of the coil spring.
The spring, cantilever beam and quality piece constitute elastic vibration system, when fiber grating vibration displacement sensor vibrates along with external signal, the quality piece is because inertia, still keep original quiescent condition in the short time, thereby it drives the pivot rotation to lead to the cantilever beam, it is tensile to drive the spring, the tensile volume is directly proportional with the vibration displacement who surveys, the tensile pulling force that produces of spring is transmitted simultaneously for diaphragm and fiber grating, lead to the fiber grating wavelength to change, the variation is directly proportional with the tensile volume of spring, thereby be directly proportional with the vibration displacement of fiber grating vibration displacement sensor, through detecting fiber grating wavelength variation, can reduce the vibration displacement volume.
The invention has the following beneficial effects: the fiber grating vibration displacement sensor provided by the invention has the advantages that the output quantity is in direct proportion to the vibration displacement quantity, the vibration displacement quantity can be directly measured, compared with the traditional fiber grating vibration sensor which measures the vibration acceleration quantity and calculates the displacement quantity in a secondary integration mode, the fiber grating vibration displacement sensor can avoid the error caused by the integration on low-frequency interference amplification, has higher accuracy, avoids higher requirement of integration operation on subsequent signal processing, is easier to realize, and reduces the cost.
Drawings
Fig. 1 is a structural front view of a fiber grating vibration displacement sensor provided by the invention.
Fig. 2 is a structural plan view of the fiber grating vibration displacement sensor provided by the invention.
In the figure: 1-front facade; 2-rear vertical face; 3-left vertical face; 4-right vertical face; 5-top surface; 6-bottom surface; 10-a housing; 20-a rotating shaft; 30-coil spring; 40-cantilever beam; 50-a mass block; 60-a membrane; 70 fiber grating.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings.
As shown in fig. 1, a fiber grating vibration displacement sensor is characterized by comprising: a hollow shell 10 enclosed by a front vertical surface 1, a rear vertical surface 2, a left vertical surface 3, a right vertical surface 4, a top surface 5 and a bottom surface 6; a rotating shaft 20 arranged on the front vertical surface 1 and the rear vertical surface 2 of the shell 10, wherein the rotating shaft 20 can freely pivot relative to the shell 10; preferably, the front vertical surface 1 and the rear vertical surface 2 of the housing 10 are provided with smooth circular holes, and two ends of the rotating shaft 20 are supported in the circular holes and matched with the circular holes in size, so that the rotating shaft 20 can rotate freely. A membrane 60 fixed to the bottom surface 6 and extending vertically upward; the inner end of the coil spring 30 is fixed at the front part of the rotating shaft 20, and the outer end of the coil spring 30 is connected with the top end of the diaphragm 60 in a welding or threaded connection mode; the other end of the diaphragm 60 is fixed on the bottom surface 6 of the shell 10 in a welding or threaded manner; a cantilever beam 40 is fixedly arranged at the rear part of the rotating shaft 20, the left part of the cantilever beam 40 is fixedly connected with the rotating shaft 20, and the right end of the cantilever beam 40 is fixedly connected with a mass block 50; the mass 50 is used to pick up the vibration signal.
One end of the fiber grating 70 which is horizontally arranged is fixedly connected with the upper part of the diaphragm 60 in an epoxy adhesive bonding mode; the other end passes through a hole 11 on the left vertical surface 3 of the shell 10 and is fixedly connected with the shell 10 in the hole 11 in an epoxy adhesive bonding mode for measuring vibration signals.
The fiber grating 70 is perpendicular to the membrane 60, and when the fiber grating 70 is connected with the hole 11, a certain initial pre-tension is applied to the fiber grating 70, wherein the pre-tension is 0.1-0.5N.
There is a certain pre-stress in the coil spring 30 so that the elastic system of mass 50 and coil spring 30 is in equilibrium when the sensor is placed vertically.
The working principle of the fiber bragg grating vibration displacement sensor is as follows: the coil spring 30, the cantilever beam 40 and the mass 50 constitute an elastic vibration system, when the fiber grating vibration displacement sensor vibrates with an external signal in the direction shown in fig. 1, and when the vibration frequency is higher than the resonance frequency, the mass block 50 still keeps the original static state in a short time due to inertia, so that the cantilever beam 40 rotates relative to the rotating shaft 20 to drive the coil spring 30 to stretch, the stretching amount is in direct proportion to the vibration displacement of the fiber grating vibration displacement sensor, the tensile force generated by the stretching of the coil spring 30 is simultaneously transmitted to the diaphragm 60 and the fiber grating 70, the wavelength of the fiber grating 70 is changed, the variation amount is in direct proportion to the stretching amount of the coil spring 30, so as to be in direct proportion to the vibration displacement of the fiber bragg grating vibration displacement sensor, by detecting the wavelength variation of the fiber bragg grating 70 and calibrating the wavelength variation with the standard vibration displacement, the reduction vibration displacement amount can be output through the wavelength change of the fiber grating vibration displacement sensor.
The fiber grating vibration displacement sensor changes the resonance frequency of the fiber grating vibration displacement sensor by adjusting the mass of the mass block 50, and changes the sensitivity and the resonance frequency of the fiber grating vibration displacement sensor by adjusting the elasticity of the coil spring 30. Specifically, if the mass 50 has a mass ofmThe coil spring 30 has an equivalent elastic coefficient ofkThe resonant frequency of the fiber grating vibration displacement sensor is
（1）
Thus, reducing the spring constant of the coil spring 30 or increasing the mass of the mass 50 can lower the resonant frequency of the sensor.
Suppose that the vibration sensor senses a vibration displacement amplitude∆xThe relative displacement amplitude of the mass 50 and the housing 10 is∆xThereby rotating the coil spring 30, resulting in the coil spring 30 having a tensile force ofk∆xNeglecting the elasticity of the diaphragm 60, the axial strain of the fiber grating 70 becomes
（2）
Wherein,A f ，E f the change of the wavelength of the fiber grating 70 is obtained from the axial strain of the fiber grating 70, which is the cross-sectional area of the fiber grating and the elastic modulus of the fiber grating material
（3）
Wherein,λ B which is the center wavelength of the fiber grating 70,p e is the elasto-optic coefficient of the fiber grating material, so that the sensitivity of the sensor can be obtained
（4）
It can be seen that the sensitivity of the sensor is proportional to the spring rate of the coil spring 30, and can be adjusted by adjusting the spring rate of the coil spring 30.
Preferably, the mass 50 is about 100 g and the coil spring 30 has an equivalent spring constant of about 30N/m, so that the sensor has a sensitivity of about 400 pm/m, a resonant frequency of about 2.8 Hz, and a sensor operating frequency higher than the resonant frequency.
Claims (4)
1. A fiber grating vibration displacement sensor, comprising: the hollow shell is formed by a front vertical surface, a rear vertical surface, a left vertical surface, a right vertical surface, a top surface and a bottom surface in a surrounding mode;
the rotating shafts are arranged on the front vertical surface and the rear vertical surface of the shell and can freely pivot relative to the shell; a diaphragm fixed on the bottom surface and extending vertically upwards;
the inner end of the coil spring is fixed at the front part of the rotating shaft, the outer end of the coil spring is connected with the top end of the diaphragm, and the other end of the diaphragm is fixed on the bottom surface of the shell;
the rear part of the rotating shaft is fixedly provided with a cantilever beam, the left part of the cantilever beam is fixedly connected with the rotating shaft, and the right end of the cantilever beam is fixedly connected with a mass block; one end of the fiber bragg grating which is horizontally arranged is fixedly connected with the upper part of the diaphragm, and the other end of the fiber bragg grating penetrates through a hole in the left vertical surface of the shell and is fixedly connected with the shell in the hole;
the spring, cantilever beam and quality piece constitute elastic vibration system, when fiber grating vibration displacement sensor vibrates along with external signal, the quality piece is because inertia, still keep original quiescent condition in the short time, thereby it drives the pivot rotation to lead to the cantilever beam, it is tensile to drive the spring, the tensile volume is directly proportional with the vibration displacement who surveys, diaphragm and fiber grating are given simultaneously to the tensile pulling force that produces of spring, lead to the fiber grating wavelength to change, the variation is directly proportional with the tensile volume of spring, thereby be directly proportional with the vibration displacement of fiber grating vibration displacement sensor, through detecting the fiber grating wavelength variation, reduction vibration displacement volume.
2. The fiber grating vibration displacement sensor of claim 1, wherein the fiber grating is perpendicular to the diaphragm, and an initial pre-tension is applied to the fiber grating.
3. The fiber grating vibration displacement sensor of claim 1, wherein the coil spring has a pre-stress such that the spring system of the mass and the coil spring is in equilibrium when the sensor is in a vertical position.
4. The fiber grating vibration displacement sensor according to claim 1, wherein the fiber grating vibration displacement sensor changes the resonant frequency of the fiber grating vibration displacement sensor by adjusting the mass of the mass block, and changes the sensitivity and the resonant frequency of the fiber grating vibration displacement sensor by adjusting the elasticity of the coil spring.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510748195.2A CN105203202B (en) | 2015-11-06 | 2015-11-06 | Optical fiber raster vibration displacement sensor |
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| CN201510748195.2A CN105203202B (en) | 2015-11-06 | 2015-11-06 | Optical fiber raster vibration displacement sensor |
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| CN105203202A CN105203202A (en) | 2015-12-30 |
| CN105203202B true CN105203202B (en) | 2018-07-20 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108240859B (en) * | 2016-12-26 | 2020-12-01 | 深圳太辰光通信股份有限公司 | Parameter design method of fiber grating vibration sensor |
| CN106597013A (en) * | 2017-01-20 | 2017-04-26 | 沈阳建筑大学 | Fiber grating accelerometer with adjustable sensitivity |
| CN110065527A (en) * | 2019-03-21 | 2019-07-30 | 北京交通大学 | A kind of railway signal occlusion auxiliary system based on fiber grating |
| CN111076854B (en) * | 2020-02-24 | 2024-06-11 | 天津师范大学 | Fiber bragg grating sensor for monitoring pressure of ship structure under wave load and application |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100585407C (en) * | 2007-04-11 | 2010-01-27 | 中国科学院半导体研究所 | Optical fibre grating accelerometer based on cantilever beam deflection |
| CN102772200B (en) * | 2012-08-06 | 2013-12-18 | 山东省科学院激光研究所 | Pulse-taking signal sensor probe and optical fiber pulse-taking information acquisition system |
| CN104457957A (en) * | 2013-09-23 | 2015-03-25 | 同方威视技术股份有限公司 | Fiber bragg grating sensor |
| CN203785779U (en) * | 2013-12-31 | 2014-08-20 | 国家电网公司 | Dual-FBG (Fiber Bragg Grating) vibrating sensor used for liquid medium |
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