Modal estimation of a cantilever using aliased video images

This study presents how to extract the vibration modes of a structure using a digital movie recording function in a general consumer-grade digital camera rather than high-speed cameras. Based on the under-sampled vibration snap-shot images with non-uniform sampling method, it is possible to estimate the actual frequency of vibration using fan-fold paper method, and to extract the operational deflection shape (ODS) using proper orthogonal decomposition (POD) method from the sampling data. To verify the proposed method, the cantilever vibration experiment and the ensemble data extraction was performed. The results show the effective extraction of each experimental resonant mode at much higher frequency than the video sampling rates.