Vibration measurement method based on point tracking for irregular structures

A novel vibration measurement method through binocular photogrammetry is proposed to solve the problem of vibration sensing for 3D structures with irregular surfaces. Radial and tangential distortions in the image modeling process are considered for camera calibration through nonlinear optimization with Levenberg-Marquardt algorithm. Precise positioning, tracking and matching techniques are analyzed and developed in image processing. As an example, a wind turbine blade's vibration is photographed and calculated, and the measured vibration displacement is consistent with that of the hammer method. The result shows that the relative errors of the first and second order natural vibration frequencies are below 4%. The proposed photogrammetry method is simple, efficient, feasible and reliable, and can be applied to the field of dynamic testing of large irregular structures.