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Open AccessArticle

A Vision-Based Sensor for Noncontact Structural Displacement Measurement

Department of Civil Engineering and Engineering Mechanics, Columbia University, New York, NY 10027, USA
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Academic Editor: Vittorio M.N. Passaro
Sensors 2015, 15(7), 16557-16575; https://doi.org/10.3390/s150716557
Received: 30 April 2015 / Revised: 24 June 2015 / Accepted: 6 July 2015 / Published: 9 July 2015
(This article belongs to the Section Physical Sensors)
Conventional displacement sensors have limitations in practical applications. This paper develops a vision sensor system for remote measurement of structural displacements. An advanced template matching algorithm, referred to as the upsampled cross correlation, is adopted and further developed into a software package for real-time displacement extraction from video images. By simply adjusting the upsampling factor, better subpixel resolution can be easily achieved to improve the measurement accuracy. The performance of the vision sensor is first evaluated through a laboratory shaking table test of a frame structure, in which the displacements at all the floors are measured by using one camera to track either high-contrast artificial targets or low-contrast natural targets on the structural surface such as bolts and nuts. Satisfactory agreements are observed between the displacements measured by the single camera and those measured by high-performance laser displacement sensors. Then field tests are carried out on a railway bridge and a pedestrian bridge, through which the accuracy of the vision sensor in both time and frequency domains is further confirmed in realistic field environments. Significant advantages of the noncontact vision sensor include its low cost, ease of operation, and flexibility to extract structural displacement at any point from a single measurement. View Full-Text
Keywords: vision sensor; displacement; template matching; upsampled cross correlation; subpixel resolution; civil engineering structures vision sensor; displacement; template matching; upsampled cross correlation; subpixel resolution; civil engineering structures
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Feng, D.; Feng, M.Q.; Ozer, E.; Fukuda, Y. A Vision-Based Sensor for Noncontact Structural Displacement Measurement. Sensors 2015, 15, 16557-16575.

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