Fiber Bragg grating microphone system for condition-based maintenance of industrial facilities

This paper presents a multipoint fiber Bragg grating (FBG) sensing system operating as a precision microphone. This instrument aims to become the best performing technology for condition-based maintenance (CBM) of critical elements, like ball bearings and cogwheels, embedded in industrial manufacturing machineries. The system architecture is based on the simple matched-laser principle, leading to a low-cost and high-sensitivity system, operating in time and wavelength multiplexing mode. Then, heavy signal processing is applied, providing an outstanding performance improvement of 59 dB in terms of signal-to-noise ratio. A demonstration of condition-based maintenance operation has been performed using standard models of ball bearing sound spectra. Compared to traditional microphones applied to CBM, the signal processing-powered FBG system provides remarkable advantages in terms of sensitivity and rejection of environment noise, providing an improvement of cost-effectiveness of CBM.