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Smart Structures and Systems Volume 24, Number 5, November 2019 , pages 649-657 DOI: https://doi.org/10.12989/sss.2019.24.5.649 |
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Drift error compensation for vision-based bridge deflection monitoring |
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Tian Long, Zhang Xiaohong and Pan Bing
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| Abstract | ||
| Recently, an advanced video deflectometer based on the principle of off-axis digital image correlation was presented and advocated for remote and real-time deflection monitoring of large engineering structures. In engineering practice, measurement accuracy is one of the most important technical indicators of the video deflectometer. However, it has been observed in many outdoor experiments that data drift often presents in the measured deflection-time curves, which is caused by the instability of imaging system and the unavoidable influences of ambient interferences (e.g., ambient light changes, ambient temperature variations as well as ambient vibrations) in non-laboratory conditions. The non-ideal unstable imaging conditions seriously deteriorate the measurement accuracy of the video deflectometer. In this work, to perform high-accuracy deflection monitoring, potential sources for the drift error are analyzed, and a drift error model is established by considering these error sources. Based on this model, a simple, easy-to-implement yet effective reference point compensation method is proposed for real-time removal of the drift error in measured deflections. The practicality and effectiveness of the proposed method are demonstrated by in-situ deflection monitoring of railway and highway bridges. | ||
| Key Words | ||
| off-axis digital image correlation; video deflectometer; reference point compensation method | ||
| Address | ||
| Tian Long: School of Science, China University of Geosciences, Beijing 100083, China Zhang Xiaohong and Pan Bing: Institute of Solid Mechanics, Beihang University, Beijing 100191, China | ||