Vibration measurements with multiple cameras

This paper presents a simulation and experimental study on the measurement with multiple cameras of the flexural deflection shape of a beam excited by a transverse force at the fundamental resonance frequency, which gives a good estimate of the first flexural natural mode shape. The first part of the study presents the simplified optical model employed to simulate how the accuracy of the measurements vary with respect to: a) the distance of the cameras from the structure; b) the elevation angles formed by the optical axes of the cameras and the beam plane; c) the angle of aperture between pairs of cameras; d) the resolution of cameras and e) the number of cameras. The second part of the study provides experimental results taken on a beam rig and camera setup assembled using off the shelf devices. The study shows that multi-cameras setups with low-resolution/high frame-rate cameras can be effectively employed to measure flexural vibrations of distributed structures up to audio frequency ranges.