大型复杂铸锻件三维扫描测量与数据处理方法研究

发布时间：2018-06-08 01:50

本文选题：三维激光扫描 + 数据处理　；参考：《沈阳工业大学》2017年硕士论文

【摘要】：对于大型复杂锻铸件的三维点云数据处理一直是逆向反求过程中获得零件外形尺寸的一个关键环节。如何从散乱的、多噪点的点云数据中得到无噪点、光滑的三维点云,一直是相关研究的重点。依据从三维激光扫描仪获取的散乱点云中噪声点的特征进行分类,并提出一种分步去噪及光顺方法。首先用改进格网阀值法去除第一类噪点,用格网法去除第二类噪点,最后用三维双边滤波法对上述数据进行光顺处理。结果表明该方法不仅有效去除了锻铸件的三维点云数据的噪声点,同时获得了光滑的测量表面,保留了尖锐特征。三维激光扫描技术具有着分辨率高、准确度高和效率高等优点,但在实际应用中存在诸多影响扫描精度的因素。针对三维激光扫描技术在反求过程中的误差问题,详细分析了测量仪器自身误差和测量后期数据处理中对精度产生影响的因素。实验设备为TOUCH Handyscan三维激光扫描仪并基于Geomagic Studio分别对实验测量后处理过程中的迭代次数、平滑度、点云拼接、光顺程度和松弛网格的强度与曲率等因素进行了对比实验,并得出影响采集误差的影响因数的主次,最后提出了如何提高三维激光扫描数据精度的一些改进措施和注意事项。实验发现平滑度、光顺程度和松弛强度对实验后处理精度影响相对较大,对于大型复杂锻铸件的松弛强度范围在2-4级为宜,特殊情况可以考虑5-8级强度。松弛曲率影响的标准偏差远远小于松弛强度,并且标准偏差与松弛曲率成反比,与松弛强度成正比。对于大型复杂锻铸件的松弛曲率范围在5-8级为宜,特殊情况可以考虑1-4级曲率。
[Abstract]:The 3D point cloud data processing for large and complex forging parts is always a key step in the reverse process to obtain the shape dimensions of the parts. How to get noiseless and smooth 3D point clouds from scattered, multi-noisy point cloud data has been the focus of relevant research. According to the features of noise points in scattered point cloud obtained from 3D laser scanner, a step by step de-noising and smoothing method is proposed. First, the improved grid threshold method is used to remove the first type of noise, and the second kind of noise is removed by the grid method. Finally, the above data are faired by using the three-dimensional bilateral filtering method. The results show that this method not only effectively removes the noise points of the 3D point cloud data of the forgings, but also obtains a smooth measuring surface and retains the sharp features. 3D laser scanning technology has the advantages of high resolution, high accuracy and high efficiency, but there are many factors that affect the scanning accuracy in practical application. Aiming at the error of 3D laser scanning technology in reverse process, the error of measuring instrument itself and the factors that affect the accuracy in the later data processing are analyzed in detail. The experimental equipment is TOUCH Handyscan 3D laser scanner, and based on Geomagic Studio, the factors such as iteration number, smoothness, point cloud splicing, fairing degree and the intensity and curvature of relaxation mesh in the process of post-processing are compared. The main and secondary factors affecting the acquisition error are obtained. Finally, some improvement measures and points for attention on how to improve the accuracy of 3D laser scanning data are put forward. It is found that smoothness, smoothness and relaxation strength have great influence on the post-treatment precision. The relaxation strength range of large and complex forgings is 2-4, and 5-8 grade strength can be considered in special cases. The standard deviation affected by relaxation curvature is much smaller than that of relaxation strength, and the standard deviation is inversely proportional to relaxation curvature and is directly proportional to relaxation strength. The relaxation curvature range of large complex forgings is in the range of 5-8, and the 1-4 stage curvature can be considered in special cases.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN249

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