基于单摄像机的三维位移测试方法

Three-Dimensional Displacement Measurement Based on Single CCD Camera

基于三维位移测量手段在工程技术领域的必要性和重要性,开展了基于单摄像机和数字图像相关的三维位移测试方法研究。基于图像位移场矢量中心和斜率与面内和离面位移的分别对应关系,采用Savitzky-Golay(SG)微分滤波器分离图像位移子区内的常数项与一次项,可实现物体三维位移分量的有效分离。以针孔摄像机成像模型为基础,开展了相应的数值模拟实验及悬臂梁端部受载的实验,发展了与三维线性变形对应的散斑图模拟方法,验证了基于二阶位移模式的牛顿-拉夫森迭代法的精度和适用性。数值模拟与实验结果均验证了三维位移测试方法用于实现物体三维位移重构的可行性和优越性。

Owing to the necessity and importance of the technique of three-dimensional （3D） displacement measurement in the filed of engineering, a 3D displacement measurement system based on single CCD camera and digital image correlation is developed. With regard to the relationship between the center and the slope of the displacement vector and displacements in- and out-of the object plane, two dimensional Savitzky-Golay （SG） digital differentiator （an operator based on local subset coordinates） is employed to calculate constant terms （corresponding to the in-plane components） and the first order terms （corresponding to the out-of-plane components）. On the theoretical basis of the pin-hole camera imaging model, a numerical simulation and an experiment on a non-uniformly deformed cantilever beam are conducted. In addition, the simulated speckle images associated with the 3D deformation are generated, which is further employed to validate the effectiveness and precision of the Newton-Raphson iterative method with a shape function of the second order. Simulated and experimental results demonstrate that both in-plane and out-of-plane displacements can be accurately retrieved using the proposed method.