Camera-Based Micro-Vibration Measurement for Lightweight Structure Using an Improved Phase-Based Motion Extraction

Video cameras are capable to collect high-density spatial data as each pixel is a sensor. An issue is that the video data is difficult to convert into the motion information, such as displacement. This paper presents a novel camera-based vibration measurement methodology for the lightweight structure. First, the phase-based motion extraction method is improved by directly transforming the phase variations into the displacement without the computation of phase gradient. The displacement is then converted into acceleration information to describe the vibration. Moreover, the proposed vibration measurement is investigated for a lightweight structure without attached sensors to change the physical properties. The measurements of the acceleration signals from camera and accelerometer are compared for verification. The experimental results for the effect of mass-loading, different camera parameters and down-sampling on the measurement validate the effectiveness of the proposed method.