Design and Testing of a 2D Optical Fiber Sensor for Building Tilt Monitoring Based on Fiber Bragg Gratings

Chung-Ru Chao,Wei-Lun Liang,Tsair-Chun Liang

doi:10.3390/asi1010002

Abstract

In this paper, a new type of optical fiber tilt sensor based on fiber Bragg grating (FBG) is presented for 2D dual-axis tilt angle sensing. The tilt sensor is composed of two cylindrical floats suspended in water, connected with FBG. When the external environment causes the tilting of the sensor, the surface of the liquid within the container will form a new balanced liquid surface plane due to the gravity and change the height of the liquid at different locations in the container. So the buoyancy force of the cylindrical floats of the sensor will vary with the depth of liquid, thus the changed FBG strain will cause the FBG reflection central wavelength shift. According to the measured central wavelength shift by the optical spectral analyzer (OSA), we can obtain the two-axis tilt angle of the sensor. The proposed sensor can detect a tilt angle range of −5 degrees to +5 degrees and achieve a sensitivity of 0.1° with optical spectrum analyzer resolution of 0.01 nm. Due to its good sensing linearity, the proposed sensor can be applied in building tilt measurement.

Highlights

Optical fiber sensors made of silicon-based optical fibers or polymer optical fibers have been commonly utilized for numerous types of physical detection [1,2,3,4,5,6,7,8,9,10,11,12] because a fiber sensor has many features that are better than conventional electronic sensors
If the sensor was gradually tilted from 0 degrees to a negative angle, FBG2 gradually shrank as the tilt angle increased, and the reflection center wavelength of FBG2 began to shift to a short wavelength band
In this paper, we have experimentally investigated a 2D tilt sensor based on two fiber Bragg grating (FBG) with orthogonal setup onto cylindrical floats for 2D tilt measurement

Summary

Introduction

Optical fiber sensors made of silicon-based optical fibers or polymer optical fibers have been commonly utilized for numerous types of physical detection [1,2,3,4,5,6,7,8,9,10,11,12] because a fiber sensor has many features that are better than conventional electronic sensors. Several fiber sensor designs based on FBG have been reported for various applications, such as liquid level monitoring [13], transverse force sensing [14], concentration measurement [15], biomedical measurement [16,17], pressure [18,19,20], displacement [21,22], temperature [23,24], and ground vibration [25]. TThhee CCoonnffiigguurraattiioonn ooff tthhee PPrrooppoosseedd TTiilltt SSeennssoorr FFiigguurree 11 sshhoowwsstthheessimimppleleaarcrchhitietecctuturereoof fththeeopotpictiaclapl aptahthofotfhtehdeedsiegsnigonf othf ethseensseinnsginsgysstyemste, min, winhwichhicthhethperopproopseodsefdibfiebretrilttilstesnesnosroor bosbesrevrevsesthtehetwtwooFFBBGGssrreefflleecctitninggtthhee cceenntteerr wwaavveelleennggtthh sshhiifftt aammoouunntt ttoo ddeetteerrmmiinnee tthhee ttiilltt ooff tthhee aazziimmuutthh aanndd aannggllee..

Results

Conclusion