Transverse vibration measurement of beam structure using based on subpixel-based edge detection and point tracking

Transverse vibration measurement of beam structures based on computer vision has been widely used, but most visual measurement methods require the installation of artificial markers at the measured positions. This makes the measurement of vibrations in some key position of beam structures difficult due to their inaccessibility. Therefore, the development of target-less approaches is important for some engineering applications. In this paper, a method for measuring displacement and vibration of beam structures visually is presented based on sub-pixel edge point tracking. Combining the principle of coordinate space transformation and the two-dimensional normal distribution characteristics of false edge parameters, false edges are eliminated to determine the position of structural edges accurately. This allows measurement of beam deflection and point tracking of the beam structure’s vibration. The effectiveness of the proposed method is verified through a cantilever beam vibration experiment and the measured data are compared using a traditional piezoelectric sensor (eddy current displacement sensor and accelerometer) and digital image correlation method. Compared with the traditional piezoelectric sensor methods, the maximum difference of the measured displacement was less than 2.4%. Compared with the digital image correlation method, the time series correlation of the proposed method with the reference measurements was 0.35% higher, and the main vibration frequency error was 0. The experiment proves that the proposed method can be used as an effective visual measurement method for target-less tracking of the transverse vibration of beam structures.