Papers by Author: Lei Chen

Abstract: In reverse engineering, complex free-form shaped parts are usually digitized quickly and accurately using the newly arisen non-contact measuring methods. However, they produce extremely dense point data at great rate. Not all the point data are necessary for generating a surface CAD model. Moreover, owing to inefficiencies in storing and manipulating them it takes a long time to generate a surface CAD model from the measured data. Therefore, an important task is to reduce the large amount of data. After analyzing the existing methods developed by other researchers, a new data reduction method, which based on bi-directional point cloud slicing, is presented in this paper. Using the proposed method, point cloud can be reduced while considering geometric features in both two parametric directions. Finally, a face model is used to verify the effectiveness of the proposed method and experimental results are given.

Abstract: The error compensation technique is used to improve the accuracy of non-contact high-precision measuring system. To ensure the accuracy of the high-precision non-contact four-coordinate blade profile measuring system, the geometric and thermal error compensation model is proposed in this paper. The system is composed of three orthogonal coordinate axes (X, Y and Z) and a rotation axis R. The coordinate transformation matrix can be calculated by the mathematical model of rigid body which is established according to the related theoretical analysis. Three-beam interferometer and standard gauge block are adopted to verify the geometric error of the system. In the thermal deformation error compensation, wavelet neural network model is established. The thermal and geometric error compensation methods are analyzed and the experimental results are given.