欢迎访问林业科学,今天是

林业科学 ›› 2018, Vol. 54 ›› Issue (5): 127-134.doi: 10.11707/j.1001-7488.20180514

• 论文与研究报告 • 上一篇    下一篇

基于雷达波的树木躯干内部缺陷探测识别

肖夏阳, 文剑, 肖中亮, 李伟林, 张厚江   

  1. 北京林业大学工学院 北京 100083
  • 收稿日期:2016-09-12 修回日期:2017-04-11 出版日期:2018-05-25 发布日期:2018-06-05
  • 基金资助:
    国家自然科学基金项目(31328005,31600589);中央高校基本科研业务费专项资金项目(2017ZY27)。

Detection and Recognition of Tree Trunk Internal Structure Based on Radar

Xiao Xiayang, Wen Jian, Xiao Zhongliang, Li Weilin, Zhang Houjiang   

  1. School of Technology, Beijing Forestry University Beijing 100083
  • Received:2016-09-12 Revised:2017-04-11 Online:2018-05-25 Published:2018-06-05

摘要: [目的]采用探地雷达对木质体内部缺陷进行断层扫描探测,研究基于雷达波的树木内部层面反射特征识别算法,为雷达波无损测试技术在树木内部结构和缺陷的解析、定位及分布表征提供理论依据。[方法]采用900 MHz介质耦合树木雷达对柳木试件进行断层扫描,研究实现阈值法、匹配滤波器法和希尔伯特积算法获取缺陷层面的反射位置,基于层剥反演法对树木内部不同介质进行介电常数反演,求得层位的相对深度,结合三维激光扫描仪获取的树木外形轮廓点云数据,根据轮廓追踪法将雷达波B扫描图像与断层轮廓绝对位置进行映射,实现对树木内部缺陷的准确定位和表征。对3种算法分别使用FDTD正演方法进行对比验证,并应用于颐和园古柳木试件试验测试中。[结果]正演对比测试结果表明,希尔伯特积算法相较于阈值法和匹配滤波器法,对木质体内部缺陷识别效果更好。柳木试验测试结果显示,树木内部缺陷深度误差为10%,结合三维激光和外轮廓扫描技术求得的缺陷部分面积误差在5%左右。[结论]本研究提出的算法可以实现雷达波扫描图像对树木内部缺陷的准确定位和分布成像。

关键词: 雷达波, 三维激光扫描, 阈值, 匹配滤波器, 希尔伯特积, 缺陷定位

Abstract: [Objective] In order to provide a theoretical basis for the analysis, localization and distribution characterization of internal structure and defects of the radar waves by non-destructive testing technique,tree radar tomography were applied to detect internal defects of wood body, and the recognition algorithm of internal reflection features of radar trees was studied and analyzed. [Method] Tomography of Willow wood was carried out with a 900 MHz medium-coupled tree radar. The threshold value, matched filter and Hilbert's algorithm were used to obtain the reflection position of the defect layer. Based on the layer stripping inversion method, the inversion of the dielectric constant were applied for the different media in the tree,and the relative depth of the horizon were calculated,then the point cloud data of the contour of the tree obtained by the 3D laser scanner were mapped, and the absolute position of the B-scan radar image and the contour of the fault were mapped according to the contour tracing method. Therefore, the accurate positioning and characterization of the internal defects of trees were achieved. The three algorithms were respectively verified by finite difference-time-domain (FDTD) forward method, and the method is applied to the test of the ancient willow wood specimen in the Summer Palace.[Result] The results of forward comparison test show that Hilbert plot method is better than threshold method and matched filter method in identifying defects in wood body. The actual willow test results show that the depth error of defects in trees is 10%. The area error of defects calculated by 3D laser and contour scanning technology is about 5%.[Conclusion] The method proposed in this paper can realize the accurate localization and imaging distribution of the internal defects of the trees by the radar wave scanning images.

Key words: radar wave, laser scanning, threshold, match filter, Hilbert, locate abnormal

中图分类号: