Identification of structural dynamic behavior for continuous system based on videogrammetric technique

摘要

The availability of inexpensive and high-resolution commercial digital video cameras has brought forth a new area of application that based on the processing of high quality of digital images. Videogrammetry is a three-dimensional measurement technique that combines the traditional photogrammetry and the computer vision technique. This technique has been previously demonstrated to provide reliable accuracy comparable to that of the traditional sensors for dynamic measurement. Potentially, the technique can measure three-dimensional deformation time history of either a few selected targets or a continuous spatial profile on a structure. In this paper, a novel technique based on videogrammetry is proposed for investigation of structural dynamic behavior, which can measure deformation with sub-pixel accuracy is first established to extract the temporal-spatial deformation of a structure. A simple modal identification method in frequency domain is then applied to extract structural vibration parameters using dynamic responses reconstructed from the image sequence. For demonstration of proof-of-concept, a lab test of identifying the free vibration of a steel cantilever beam is performed. Results have indicated that the proposed technique can achieve a good agreement with the analytical analysis, and show its significant potential for vibration-based real applications.