Research On Model Registration Method And Its Application In Digital Measurement

Model registration is an key technique in digital measurement field. Registration appeared firstly in the medical diagnosis field and image processing field. It is widely applied to nondestructive testing, reverse engineering, virtual reality, robot and flexible assembly now. It is the precondition of part testing, model evaluation, error analysis and data integration. Registration precision and registration speed are two most important factors to scale validity, thereby fast and accurate registration research has important theory significance and engineering application value in improving digital measurement accuracy and digital measurement efficiency.Aiming at the problem, the thesis discusses the selection of contour dominant points, the registration algorithm based on restriction region, acceleration algorithms of registration, the establishment of registration error model and other key technologies, moreover, a software prototype system is developed. This will solve the workpiece's localization, nondestructive testing and nondestructive evaluation on the turbine blade of aeroengine. The main research contents and contributions in the thesis are as follows:(1) According to shape theory and estimation theory, second selection algorithm is put forward in order to extract contour dominant points. Compared with symmetrical extraction algorithm and polygonal approximation algorithm, the algorithm can extract contour's typical character of the blade effectively, for example, leading edge and trailing edge. The algorithm also avoids the traditional algorithm's disadvantage that some characteristic points are lost. Furthermore, redundant data can be removed. At last, approximation attribute between contour dominant points and original shape is evaluated by approximation model. Contour dominant points obtained by second selection algorithm are advantageous to improve the following registration precision and registration speed.(2) Aiming at accuracy of model registration, it is adopted that initial registration and accuracy registration are combined. Initial registration can reduce the difference between models availably and make preparations for accuracy registration. In the process of accuracy registration, the notion of restriction region and the registration algorithm based on restriction region are proposed. The algorithm integrates the virtues of other registration algorithms and change six variables' optimization to three variables' optimization, then restriction region weight factor is imported and two object functions are proposed, finally confirmation analysis method is proposed and accuracy registration is realized. The experiments show this algorithm has better registration accuracy than traditional registration algorithms, moreover, it has great adaptability and can solve 2D/3D registration well.(3) Aiming at the real time performance of model registration, the thesis adopts two methods to accelerate the registration for the registration algorithm based on restriction region. Improved iterative directional acceleration algorithm is presented...