Integrated monitoring scheme for a maglev guideway using multiplexed FBG sensor arrays

In the structural monitoring of maglev guideways, electromagnetic interference (EMI) can be a significant problem, as the maglev train is powered by high-voltage electric feeding systems. Recently, researchers have successfully applied fiber optic sensors to modern railway structures, mainly because they offer EMI immunity. This study presents an integrated monitoring scheme for a maglev guideway using wavelength division multiplexing (WDM)-based fiber Bragg grating (FBG) sensors. The physical quantities such as strains, curvatures, and vertical deflections are measured in field tests. The strains are directly measured from multiplexed FBG sensors at various locations on a test bridge followed by curvature calculations based on the plane section assumption. Vertical deflections are then estimated using the Bernoulli beam theory and regression analyses. Frequency information obtained from the proposed method is compared with those from a conventional accelerometer. Verification tests were conducted on a newly developed Korean maglev test track at different vehicle speeds.