基于组合特征图案的单目视觉三维振动测量

Three-Dimensional Vibration Measurement of Monocular Vision Based on Composite Feature Pattern

针对结构三维振动同步测量问题,提出一种基于组合特征图案的单目视觉三维振动测量方法。组合特征图案由圆形图案和正弦条纹图案组成并喷涂或粘贴于待测结构表面,采用单目相机对该组合特征图案进行连续成像。运用图像重心算法提取圆形特征的重心坐标,求出结构平行于成像平面的二维振动信息,再运用能量重心频谱校正算法提取中心位置正弦条纹的密度信息,据此求出垂直于成像平面的振动信息,从而实现结构三维振动的同步测量。通过模拟仿真分析了图像噪声、成像分辨率、图案动态特征提取算法对测量性能的影响。对悬臂梁在脉冲激励下的空间自由振动进行实验测量,并与Hough变换圆检测算法的提取信号进行对比,结果表明该方法能够对结构三维振动位移信息进行高精度的同步测量。

Aiming at the problem of simultaneous measurement of three-dimensional(3D)vibration of structures,a monocular vision 3D vibration measurement method based on composite feature patterns is proposed.A monocular camera is used in continuous imaging of the composite feature pattern,which is composed of the circular patterns and sinusoidal fringe patterns and pasted on the surface of the structure to be tested.Barycenter coordinates of circle pattern features are extracted by the image barycenter algorithm,which is used to calculate the two-dimensional vibration information parallel to the imaging plane.Meanwhile,the density information of sinusoidal fringes is extracted by the spectral centrobaric correction method(SCCM),which is used to calculate the vibration information perpendicular to the imaging plane,and then the 3D vibration of the structure can be measured synchronously.The effects of image noise,imaging resolution,and pattern dynamic feature extraction algorithm on measurement performance are analyzed by simulation.Experimental measurement for a cantilevered beam excited by an impulse excitation is carried out,whose results are compared with the ones obtained by Hough transform circle detection algorithm.The experimental results demonstrate that the proposed method can simultaneously measure 3D vibration information of structures with high precision.