Review of the Strain Modulation Methods Used in Fiber Bragg Grating Sensors

Li, Kuo

doi:10.1155/2016/1284520

Cited by 29 publications

(14 citation statements)

References 84 publications

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“…An experiment was performed between FBG and strain gauge in Ref. 77, where FBG-based strain sensing showed more accurate results as compared to strain gauge method. Two FBG and strain gauge were pasted on one side of equi-intensity cantilever beam, and on other side different weights were added that were to be tested.…”

Section: Fbg-based Strain Sensorsmentioning

confidence: 99%

Fiber Bragg grating sensors for monitoring of physical parameters: a comprehensive review

2020

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Fiber Bragg grating has embraced the area of fiber optics since the early days of its discovery, and most fiber optic sensor systems today make use of fiber Bragg grating technology. Researchers have gained enormous attention in the field of fiber Bragg grating (FBG)-based sensing due to its inherent advantages, such as small size, fast response, distributed sensing, and immunity to the electromagnetic field. Fiber Bragg grating technology is popularly used in measurements of various physical parameters, such as pressure, temperature, and strain for civil engineering, industrial engineering, military, maritime, and aerospace applications. Nowadays, strong emphasis is given to structure health monitoring of various engineering and civil structures, which can be easily achieved with FBG-based sensors. Depending on the type of grating, FBG can be uniform, long, chirped, tilted or phase shifted having periodic perturbation of refractive index inside core of the optical fiber. Basic fundamentals of FBG and recent progress of fiber Bragg grating-based sensors used in various applications for temperature, pressure, liquid level, strain, and refractive index sensing have been reviewed. A major problem of temperature cross sensitivity that occurs in FBG-based sensing requires temperature compensation technique that has also been discussed in this paper.

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Section: Fbg-based Strain Sensorsmentioning

confidence: 99%

Fiber Bragg grating sensors for monitoring of physical parameters: a comprehensive review

2020

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“…Here, the wavelength separation shift of two FBGs is proportional to the imposed force while the cross-sensitivity problem of strain and temperature in force sensing is solved. Other temperature insensitive methods can be found in literatures [ 16 , 17 , 18 ]. Some of them use only one FBG to obtain temperature insensitivity, or use two FBG allows to determine temperature and two direction force.…”

Section: Principle Of the Load Cellmentioning

confidence: 99%

The Reusable Load Cell with Protection Applied for Online Monitoring of Overhead Transmission Lines Based on Fiber Bragg Grating

Guo

Mao

et al. 2016

Sensors

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Heavy ice coating of high–voltage overhead transmission lines may lead to conductor breakage and tower collapse causing the unexpected interrupt of power supply. The optical load cell applied in ice monitoring systems is immune to electromagnetic interference and has no need of a power supply on site. Therefore, it has become a hot research topic in China and other countries. In this paper, to solve the problem of eccentric load in measurement, we adopt the shearing structure with additional grooves to improve the strain distribution and acquire good repeatability. Then, the fiber Bragg grating (FBG) with a permanent weldable package are mounted onto the front/rear groove of the elastic element by spot welding, the direction deviation of FBGs is 90° from each other to achieve temperature compensation without an extra FBG. After that, protection parts are designed to guarantee high sensitivity for a light load condition and industrial safety under a heavy load up to 65 kN. The results of tension experiments indicate that the sensitivity and resolution of the load cell is 0.1285 pm/N and 7.782 N in the conventional measuring range (0–10 kN). Heavy load tension experiments prove that the protection structure works and the sensitivity and resolution are not changed after several high load (65 kN) cycles. In addition, the experiment shows that the resolution of the sensor is 87.79 N in the large load range, allowing the parameter to be used in heavy icing monitoring.

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“…In the small signal analysis, we are interested in detecting small wavelength shifts around the FBG central wavelength ,0 . Focusing on small wavelength shift, we can introduce two substantial improvements to the KLT kernel, described by (7)- (11), with the aim of improving the precision sensing features.…”

Section: Improved Klt For Small Signal Analysismentioning

confidence: 99%

“…Each FBG is sensitive to strain and temperature, exhibiting a linear sensitivity over a wide sensing range [2]. FBG strain sensors are employed in structural health monitoring [6,7], avionics [8,9], vibration sensing [10][11][12][13], and seismic applications [14,15]; FBGs are also often embedded into composite materials [6]. Miniature FBG sensors are often employed in medicine for temperature [16,17] and strain sensing [18][19][20] and in harsh environments such as nuclear plants [21,22].…”

Section: Introductionmentioning

confidence: 99%

Improved KLT Algorithm for High-Precision Wavelength Tracking of Optical Fiber Bragg Grating Sensors

Tosi¹

2017

Journal of Sensors

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Fiber Bragg Gratings (FBGs) are among the most popular optical fiber sensors. FBGs are well suited for direct detection of temperature and strain and can be functionalized for pressure, humidity, and refractive index sensing. Commercial setups for FBG interrogation are based on white-light sources and spectrometer detectors, which are capable of decoding the spectrum of an FBG array. Low-cost spectrometers record the spectrum on a coarse wavelength grid (typically 78–156 pm), whereas wavelength shifts of 1 pm or lower are required by most of the applications. Several algorithms have been presented for detection of small wavelength shift, even with coarse wavelength sampling; most notably, the Karhunen-Loeve Transform (KLT) was demonstrated. In this paper, an improved algorithm based on KLT is proposed, which is capable of further expanding the performances. Simulations show that, reproducing a commercial spectrometer with 156 pm grid, the algorithm estimates wavelength shift with accuracy well below 1 pm. In typical signal-to-noise ratio (SNR) conditions, the root mean square error is 22–220 fm, while the accuracy is 0.22 pm, despite the coarse sampling. Results have been also validated through experimental characterization. The proposed method allows achieving exceptional accuracy in wavelength tracking, beating the picometer level resolution proposed in most commercial and research software, and, due to fast operation (>5 kHz), is compatible also with structural health monitoring and acoustics.

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Review of the Strain Modulation Methods Used in Fiber Bragg Grating Sensors

Cited by 29 publications

References 84 publications

Fiber Bragg grating sensors for monitoring of physical parameters: a comprehensive review

Fiber Bragg grating sensors for monitoring of physical parameters: a comprehensive review

The Reusable Load Cell with Protection Applied for Online Monitoring of Overhead Transmission Lines Based on Fiber Bragg Grating

Improved KLT Algorithm for High-Precision Wavelength Tracking of Optical Fiber Bragg Grating Sensors

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