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Title |
High-Speed Railway Bridge Displacement Estimation using Accelerometer and FMCW Millimeter-Wave Radar
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Authors |
이지구(Ji-Gu Lee) ; 김기영(Ki-Young Kim) ; 이태형(Tae-Hyung Lee) ; 이종훈(Jong-Hun Lee) ; 손훈(Hoon Sohn) |
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DOI |
https://doi.org/10.11112/jksmi.2025.29.6.217 |
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Keywords |
교량 변위; 가속도계; 데이터 융합; FMCW 레이더; 고속철도; 구조물 건전성 모니터링 Bridge displacement; Accelerometer; Data fusion; FMCW radar; High-speed railway; Structural health monitoring |
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Abstract |
This study proposes a displacement estimation method for high-speed railway bridges by integrating measurements from a collocated accelerometer and a frequency-modulated continuous-wave (FMCW) millimeter-wave radar. Conventional accelerometer-based double integration is highly susceptible to low-frequency drift, whereas radar measurements often suffer from noise, line-of-sight limitations, and phase wrapping when the structural displacement exceeds half the radar wavelength. To address these issues, the proposed system automates radar target selection and determines an optimal conversion factor by comparing low-pass-filtered radar displacements with high-pass-filtered accelerometer-based displacements. An accelerometer-aided phase-unwrapping algorithm is then employed to reconstruct continuous phase histories, enabling accurate displacement estimation even under large-amplitude vibrations. Finally, a finite impulse response (FIR) filter is used to fuse low-frequency radar displacement with high-frequency accelerometer displacement, producing a refined displacement signal with reduced noise and drift. Field tests conducted on an operational high-speed railway bridge in South Korea demonstrate strong agreement with laser Doppler vibrometer measurements, with a maximum root mean square error below 0.1 mm. These results confirm the accuracy and robustness of the proposed sensing system and highlight its suitability for real-time structural monitoring under dynamic train loads.
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