Research on digital measurement technology based on point cloud data of complex surfaces

To deal with inspection difficulty in complex surfaces in product design and manufacture process, the digital measurement system consistied of data acquirement, Computer Aided Design(CAD) model and deviation analysis was proposed. It adopted gray code and phase shift technology to get point clouds of complex surfaces and used a custom-built grating to meet the demand of optical triangulation. Because point clouds and CAD model were in different coordinate system, the registration was needed. Improved Iterative Closet Point(ICP )method was proposed with translation matrix little variety to register the point cloud to CAD model. Owing to large point numbers of point clouds, it was not necessary to use all points for deviation analysis. A multi-resolution hierarchy analysis to deviation was presented. The result of deviation analysis could be referred by designers and was made as feedback to the system of design, manufacturing and measurement. The system was applied by a car lamp cover part. Application results suggested feasibility of the system.