基于数字图像相关的三维刚体位移测量方法

基于三维位移测量在工程技术领域的必要性和重要性,开展了单摄像机和数字图像相关相结合的三维刚体位移测试方法的研究.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,采用最小二乘拟合法分离图像位移场的常量项与一次项,据此,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,开展了数值模拟及硅片平移实验,发展了与三维刚体位移对应的散斑图模拟方法,验证了基于仿射变换的相关迭代法的精度和适用性.数值模拟与实验结果验证了数字图像相关方法用于实现物体三维刚体化移重构的可行性和优越性,最大测量误差为5%.

Three-Dimensional Rigid Body Displacement Measurement Based on Digital Image Correlation

Owing to the necessity and importance of the three-dimensional (3-D) displacement measurement technique in the field of engineering, a system based on a single CCD camera and a method of 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, a least-squares fit method is employed to calculate constant terms (corresponding to the in-plane component) and the first order terms (corresponding to the out-of-plane component), and the three-dimensional displacement components are separated. On the theoretical basis of the pin-hole camera imaging model, a numerical simulation and an experiment on three-dimenaional translation of a silicon wafer are conducted. The simulation method of speckle images associated with the three-dimensional rigid body displacement is developed, which is further employed to validate the effectiveness and precision of the iterative correlation method based on affine transformation. Simulated and experimental results demonstrate that both in-plane and out-of-plane displacements can be accurately retrieved with the proposed method, and the maximum error is 5%.