High-Frequency Optical Fiber Microphone for Condition-Based Maintenance (CBM)

Application

[Optical Metrology, 2013]

Daniele TosiUniversity of Limerick, Optical Fibre Sensors Research Centre

Massimo Olivero, Guido Perrone, Alberto VallanPolitecnico di Torino, Dept. of Electronics and

Telecommunications

Fiber optic microphone

High-frequency optical fiber microphone for condition-based maintenance application

Performance➡ με, nε, <nε sensing

resolution➡ Long-haul sensing

Miniature size➡ Miniature size (∅125μm +

coating)➡ Lightweight, versatile coating

Distribution➡ Time+wavelength

multiplexing➡ Quasi-distributed

Total immunity➡ Totally EMI compatible➡ Fire-safe, passive device

Fiber Bragg grating (FBG)

High-frequency optical fiber microphone for condition-based maintenance application

•Information encoded in FBG optical spectrum•Linear dependance on strain and temperature•1.08 pm/με (10.2 pm/K)•High-speed interrogation

•Information encoded in FBG optical spectrum•Linear dependance on strain and temperature•1.08 pm/με (10.2 pm/K)•High-speed interrogationReflected Bragg wavelength shifts linearly

with variation of tensile strain and temperature

High-speed interrogation

High-frequency optical fiber microphone for condition-based maintenance application

High speed, no scanning elementsShort range, high sensitivitySensitive to backreflection noise

Signal processing

High-frequency optical fiber microphone for condition-based maintenance application

Adaptive filtering•Mitigates the effect of backreflection laser noise•Applied in pre-training conditions

Frequency estimat.•Operate in low SNR, well below -35 dB•Computational complexity increase

High sensitivity, ≲0.1 nεNo real-time detection

FBG multiplexing

High-frequency optical fiber microphone for condition-based maintenance application

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FBG matrixchannel 1channel 2

channel N

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wavel. Wwavel. 2wavel. 1

Architecture

High-frequency optical fiber microphone for condition-based maintenance application

Switch

Laser array

Laser controller

Photodiode

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FBG matrix

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Prototype

High-frequency optical fiber microphone for condition-based maintenance application

Laser(s) Detector

Switch 1x2Circulator

TEC/LDC

Fiber outputDAQ output

DAQ 5kS/s

Frequency response

High-frequency optical fiber microphone for condition-based maintenance application

Voice detection

High-frequency optical fiber microphone for condition-based maintenance application

Intelligibility + peak reproduction

CBM Condition-Based Maintenance

High-frequency optical fiber microphone for condition-based maintenance application

CBM Condition-Based Maintenance

High-frequency optical fiber microphone for condition-based maintenance application

CBM Condition-Based Maintenance

High-frequency optical fiber microphone for condition-based maintenance application

EMI-prone environmentCritical location placementNoisy environmentNetwork structureLong process time

CBM model

High-frequency optical fiber microphone for condition-based maintenance application

Ahmadi, H. and Mollazade, K., "Bearing fault diagnosis of a mine stone crasher by vibration condition monitoring technique," Res. J. Appl. Sci.

Eng. Technol. 1 (2009).

Sound = f(shape) + + f(rotation/contact) + + f(damage)

Warning signal (fm)

CBM model

High-frequency optical fiber microphone for condition-based maintenance application

Ahmadi, H. and Mollazade, K., "Bearing fault diagnosis of a mine stone crasher by vibration condition monitoring technique," Res. J. Appl. Sci.

Eng. Technol. 1 (2009).

CBM model

High-frequency optical fiber microphone for condition-based maintenance application

Ahmadi, H. and Mollazade, K., "Bearing fault diagnosis of a mine stone crasher by vibration condition monitoring technique," Res. J. Appl. Sci.

Eng. Technol. 1 (2009).

Useful region

Future work

High-frequency optical fiber microphone for condition-based maintenance application

FBGsShaker

CFC(4 layer)