基于改进稀疏表示的高衰减厚壁结构超声相控阵全聚焦成像  

Total focusing method for highly attenuated thick-walled structures based on improved sparse representation

作　　者：周至伟 饶静 牛伟 Zhou Zhiwei;Rao Jing;Niu Wei(School of Instrumentation and Opto-Electronic Engineering,Beihang University,Beijing 100191,China;Xi′an Aeronautics Computing Technique Research Institute,Aviation Industry Corporation of China,Xi′an 710068,China)

机构地区：[1]北京航空航天大学仪器科学与光电工程学院,北京100191 [2]中国航空工业集团公司西安航空计算技术研究所,西安710068

出　　处：《仪器仪表学报》2024年第12期246-255,共10页Chinese Journal of Scientific Instrument

基　　金：国家自然科学基金面上项目(62271021)资助。

摘　　要：针对常规超声相控阵在检测高衰减厚壁结构中存在的缺陷特征提取较难和信噪比较低的问题,采用了一种基于改进稀疏表示的超声信号处理方法来解决以上问题。首先对超声全矩阵捕捉数据进行预处理获得分段信号及其对应的时频参数。基于分段信号的时频参数,构造出自适应Gabor子字典,再利用改进的支持匹配追踪算法对分段信号进行稀疏分解与重构。与常规正交匹配追踪算法相比,该改进支持匹配追踪算法结合了自适应Gabor子字典和l_(p)范数(0<p<1)。自适应Gabor子字典通过优化字典原子以更好地匹配信号特性,而l_(p)范数则提供了一种更灵活的稀疏度测量方式,这使得该算法能够在紧凑的字典上更精确地重构超声信号,提高了重构信号的质量。最后,对处理后的全矩阵捕捉数据采用常规全聚焦成像算法实现超声成像。实验结果表明,改进稀疏表示能够准确提取缺陷信号和提高信噪比,提高了高衰减厚壁结构内部缺陷超声图像质量。To address the challenges of extracting defect features and low signal-to-noise ratio(SNR)of conventional ultrasonic phased array in the detection of highly attenuated thick-walled structures,an ultrasonic signal processing method based on the improved sparse representation is proposed to solve the problems in this article.Firstly,the ultrasonic full matrix capture is preprocessed to obtain segmented signals and their corresponding time-frequency parameters.Building upon the parameters,the adaptive Gabor sub-dictionaries are constructed.Then,the segmented signals are sparsely decomposed and reconstructed by the improved support matching pursuit algorithm.Compared with the conventional orthogonal matching pursuit algorithm,the improved support matching pursuit algorithm combines the adaptive Gabor sub-dictionaries and l_(p)-norm(0<p<1).Atoms of the sub-dictionaries are optimized to better match the characteristics of ultrasonic signals,while a more flexible approach to measuring sparsity is provided by l_(p)-norm.They reconstruct ultrasonic signals more accurately through compact dictionaries,enhancing the quality of reconstructed signals.Finally,the total focusing method is applied to the processed full matrix capture to produce ultrasonic images.Experimental results show that the improved sparse representation can accurately extract defect signals and achieve high SNR,improving the ultrasonic image quality of internal defects contained in highly attenuated thick-walled structures.

关 键 词：高衰减厚壁结构 超声检测 信号处理 稀疏表示 全聚焦成像 

分 类 号：TH878[机械工程—仪器科学与技术] TB553[机械工程—精密仪器及机械]