CN-122017284-A - Triaxial FBG acceleration sensing and demodulation integrated system based on edge calculation

CN122017284ACN 122017284 ACN122017284 ACN 122017284ACN-122017284-A

Abstract

The invention provides an edge calculation-based triaxial FBG acceleration sensing and demodulation integrated system, which is characterized in that a miniature fiber bragg grating demodulator is packaged in a triaxial FBG acceleration sensor shell and comprises a core control and data processing module, a light source module, a photoelectric conversion module and a communication display module, wherein light output by the light source module is respectively connected with three single-axis FBG acceleration sensors through a 1x3 fiber coupler and three fiber circulators, third ports of the three circulators are respectively connected with three input ends of the photoelectric conversion module, and the core control and data processing module processes collected triaxial acceleration signals through a powerful calculation function and performs data transmission and display through the communication display module. The invention solves the high cost problem of the fiber grating acceleration sensor and the matched traditional demodulator, and realizes the triaxial fiber grating acceleration measurement and edge calculation processing with conciseness, high efficiency and low cost.

Inventors

SUN HAOYUAN
WANG XIAONA
SONG SHIDE

Assignees

大连理工大学

Dates

Publication Date: 20260512
Application Date: 20260126

Claims (10)

1. The triaxial FBG acceleration sensing and demodulating integrated system based on edge calculation is characterized by comprising a miniature fiber bragg grating demodulator packaged in a triaxial FBG acceleration sensor shell; The miniature fiber bragg grating demodulator comprises a core control and data processing module, a light source module, a photoelectric conversion module and a communication display module; the triaxial FBG acceleration sensor comprises a sensor shell and three uniaxial fiber bragg grating acceleration sensors which are packaged in the sensor shell; The light waves emitted by the light source module are respectively connected with the first ports of the three optical fiber circulators through the 1x3 optical fiber couplers, and the output of the second port of the optical fiber circulators is connected with the single-axis optical fiber grating acceleration sensor; the output end of the photoelectric conversion module is electrically connected with the input end of the core control and data processing module, and the photoelectric conversion module outputs a light intensity electric signal to the core control and data processing module; the core control and data processing module converts spectrum data into wavelength offset through a lightweight wavelength demodulation algorithm; the control output end of the core control and data processing module is electrically connected with the control input end of the light source module, and the core control and data processing module outputs a wavelength scanning driving signal to the light source module; The data output end of the core control and data processing module is electrically connected with the input end of the communication display module, and the sensing data output by the core control and data processing module is transmitted to the communication display module.
2. The three-axis FBG acceleration sensing and demodulation integrated system based on edge calculation according to claim 1, characterized in that the core control and data processing module comprises a micro-controller unit, which is fixed on a main PCB backplane; The light source module comprises a tunable laser and a high-precision multi-channel numerical control current source chip, the tunable laser is fixed on a laser bottom plate, the high-precision multi-channel numerical control current source chip is fixed on the main PCB bottom plate, the high-precision multi-channel numerical control current source chip is connected with the micro controller unit through an SPI interface, and a current output end of the high-precision multi-channel numerical control current source chip is electrically connected with a driving pin of the tunable laser through a wire; the photoelectric conversion module comprises three photoelectric detectors and three transimpedance amplifiers, wherein the optical input ends of the photoelectric detectors receive optical signals reflected by the fiber bragg gratings through optical fibers, the electric output ends of the photoelectric detectors are electrically connected with the input ends of the transimpedance amplifiers, and the output ends of the transimpedance amplifiers are electrically connected with analog-to-digital conversion pins of the micro controller unit; The communication display module comprises a display screen which is embedded and fixed on the surface of the shell of the miniature fiber bragg grating demodulator, and the display screen is electrically connected with a display interface of the microcontroller unit.
3. The triaxial FBG acceleration sensing and demodulation integrated system based on edge calculation according to claim 2, wherein the light source module further comprises a temperature control module, the temperature control module comprises a temperature control chip and a radiating fin, the temperature control chip is inserted on a main PCB base plate through a connector and is electrically connected with a thermistor pin of the tunable laser, and the radiating fin is attached to the surface of a shell of the tunable laser through a heat conducting material.
4. The triaxial FBG acceleration sensing and demodulation integrated system based on edge calculation according to claim 2, wherein the high-precision multichannel numerical control current source chip is a five-way current source chip, the model is LTC2662, and the model of the microcontroller unit is STM32H750.
5. The three-axis FBG acceleration sensing and demodulation integrated system based on edge calculation according to claim 1, wherein the lightweight wavelength demodulation algorithm comprises the steps of: S1, a microcontroller unit controls a high-precision multichannel numerical control current source to drive a tunable laser to output laser with a wavelength in linear scanning, synchronously triggers an analog-to-digital conversion module, collects a light intensity voltage sequence VI obtained by conversion of a photoelectric detector, converts the collection time sequence pi into a corresponding instantaneous wavelength sequence lambada [ i ] according to a pre-calibrated wavelength-time mapping relation, and reconstructs voltage-wavelength data pairs (lambada [ i ], VI) of a reflection spectrum; S2, filtering and preprocessing the voltage-wavelength data pairs to reduce noise, traversing all the data pairs, screening three-point groups (lambda i-1, V i-1), (lambda i, V i) and (lambda i+1, V i+1) with the light intensity voltage value being the local maximum value in three continuous sampling points, and selecting a group with the largest light intensity voltage value V i as a target three-point group to locate the peak top area of the reflection peak of the fiber grating; S3, substituting the target three-point group into a quadratic function model for fitting, calculating a function coefficient, and solving the accurate peak wavelength of the reflection peak of the fiber bragg grating according to a quadratic function vertex formula ; S4, converting the peak wavelength drift delta lambda into the axial strain epsilon of the fiber grating, and converting the strain epsilon into a measured acceleration value a by combining a mechanical model of the cantilever structure to complete real-time calculation of the triaxial acceleration.
6. The three-axis FBG acceleration sensing and demodulation integrated system based on edge calculation according to claim 5, wherein in S3, the quadratic function model is as follows: Accurate peak wavelength The formula of (2) is as follows: λ[i]+ Where Δλ is the peak wavelength shift amount of the FBG.
7. The three-axis FBG acceleration sensing and demodulation integrated system based on edge calculation according to claim 6, wherein S4 specifically comprises the following steps: When the sensor is subjected to external vibration, the peak wavelength of the fiber Bragg grating can drift along with the vibration, and the drift amount delta lambda and the axial strain epsilon of the fiber Bragg grating meet the core relation of the fiber Bragg grating: In the formula, The effective elasto-optical coefficient of the quartz optical fiber is epsilon, and the axial strain generated by the fiber Bragg grating under the vibration effect; The mechanical relationship between the strain epsilon of the cantilever beam and the acceleration a is as follows in combination with the mechanical structure of the cantilever beam of the sensor: wherein m is the mass of the mass block, L is the length of the cantilever beam, b is the width of the cantilever beam, h is the thickness of the cantilever beam, and E is the elastic modulus of the cantilever beam material; Substituting the expression of the strain epsilon into a wavelength drift formula to obtain a final calculation formula of the acceleration a: 。
8. The three-axis FBG acceleration sensing and demodulating integrated system based on edge calculation as set forth in claim 1, wherein the sensor housing is of an aluminum alloy cube structure, three single-axis fiber bragg grating acceleration sensors form three coordinate axes of a three-dimensional rectangular coordinate system, each single-axis fiber bragg grating acceleration sensor comprises a fiber bragg grating and a cantilever structure for pasting and fixing the fiber bragg grating, and a mass block is arranged at the free end of the cantilever structure.
9. The triaxial FBG acceleration sensing and demodulating integrated system based on edge calculation of claim 8, wherein the cantilever beam structure is an equal-strain beam, the cantilever beam structure and the sensor housing are integrated into a spliced structure, an optical fiber wiring groove for fixing an optical fiber is arranged in the sensor housing, and a silica gel buckle is arranged at the tail end of the optical fiber wiring groove.
10. The integrated system of tri-axial FBG acceleration sensing and demodulation based on edge calculation of claim 8, wherein the cavity in the sensor housing is a sealed cavity filled with dry gas.

Description

Triaxial FBG acceleration sensing and demodulation integrated system based on edge calculation Technical Field The invention relates to the technical field of optical fiber sensing, in particular to a triaxial FBG acceleration sensing and demodulation integrated system based on edge calculation. Background A Fiber Bragg Grating (FBG) sensor is a fiber optic sensor based on a wavelength modulation principle, which causes a change in the period or effective refractive index of the grating by a change in external physical quantity (e.g., strain, temperature, vibration), thereby causing a shift in the reflected or transmitted center wavelength thereof. By accurately measuring the wavelength drift amount, the information of the physical quantity to be measured can be inverted. The fiber bragg grating acceleration sensor based on the principle has the remarkable advantages of being intrinsically anti-electromagnetic interference, corrosion-resistant, easy to form a distributed sensing network and the like, and has important application value in the fields of structural health monitoring, aerospace, precision equipment vibration analysis and the like. The miniature fiber bragg grating demodulator is core equipment of the sensing system, and has the function of rapidly and accurately scanning and capturing the reflection spectrum of the fiber bragg grating so as to determine the center wavelength of the fiber bragg grating. At present, a typical technical scheme for realizing the acceleration measurement of the fiber bragg grating is generally formed by combining a discrete miniature fiber bragg grating demodulator with an independently packaged fiber bragg grating acceleration sensor. The existing demodulator mostly adopts a tunable laser as a scanning light source, the output wavelength of the demodulator is controlled by a driving circuit, a photoelectric detector is used for receiving the optical signal reflected by the sensing grating, and finally the data processing unit calculates the wavelength value. In the aspect of a sensor, a common FBG accelerometer mostly adopts elastic structural designs such as cantilever beams and the like to convert inertial force into axial strain of the fiber bragg grating. In practical engineering application, the demodulator and the sensor are used as two independent products and are connected through an optical fiber jumper. Although the technology of the scheme is mature, the scheme is gradually unable to meet the increasing market demands of low cost, high integration and convenient deployment. The existing separation type technical scheme has obvious defects. First, the system integration is low, resulting in high overall costs. The high-performance desk demodulator has huge volume, high power consumption and high price, and the structural design and precise packaging of the sensor further promote the total cost of the system, thereby limiting the application of the desk demodulator in large-scale and popular scenes. Second, installation and deployment are inconvenient. The traditional sensor often lacks a standardized and multi-scene-adaptive installation interface, and when complex sites such as bridges, large machinery and the like are installed, a bracket is often required to be customized or destructive punching is performed, the deployment period is long, the flexibility is poor, and the consistency of installation quality is difficult to ensure. Again, at the data processing and system architecture level, the data resolution of the existing scheme is highly dependent on the host computer or the remote server, resulting in limited system instantaneity, delayed response, and difficulty in deployment and reduced reliability in edge scenarios with poor network conditions or unattended operation. Finally, system reliability and ease of use remain to be improved. Meanwhile, the traditional demodulator is complex in operation and often depends on upper computer software, so that the on-site independent display and operation are difficult to realize, and the application scenes with high convenience requirements such as outdoor or mobile inspection cannot be met. Therefore, the integrated fiber bragg grating acceleration sensing demodulation system which has low cost, low power consumption, high integration, real-time resolving power of the edge end and convenient installation and maintenance is developed, and the integrated fiber bragg grating acceleration sensing demodulation system has urgent practical demands and important application value. Disclosure of Invention According to the technical problems of high cost, low integration level, inconvenient installation and deployment and insufficient instantaneity caused by the dependence of the data calculation on the rear end of the traditional fiber bragg grating sensing system, the triaxial FBG acceleration sensing and demodulation integrated system based on edge calculation is provided. The invention mainly utilizes the co