管道缺陷漏磁检测大容量高保真数据压缩研究

Research on MFL Inspection Large Capacity and Hi-Fi Data Compression

管道检测是石油天然气工业的一个重要课题.在管道缺陷检测中,利用缺陷的漏磁通从而设计有效的漏磁检测装置来检测缺陷是目前研究的热点,而如何对漏磁检测数据进行大容量高保真数据压缩是其中的一个关键问题.本文在分析漏磁检测原理和漏磁检测数据特征的基础上,根据对重要数据采用无损压缩、对非重要数据采用有损压缩的原则,通过数据的差分和动态范围阈值判断数据块的检测重要性,结合Huffman算法以及小波有损压缩的优点,设计了大容量高保真管道漏磁检测数据压缩算法,并利用FPGA设计了相关的数据采集压缩电路来验证和实现该算法.实验表明该算法具有较高的压缩比并能很好的再现管道检测原始数据.

Pipeline defect detection to gas and petroleum industries are considerably important since the frequently occurring corrosion, crack and other defects at the internal or external parts of those steel pipes cause production and environmental protection problems. Magnetic flux leak (MFL) theory is often utilized to design pipeline defect inspection device, and how to compress large capacity MFL detection data produced by the inspection process with high fidelity is a key problem. The paper analyzes the theory of MFL inspection with Hall sensors and the character of the MFL inspection data, uses axial differencing threshold and dynamic range threshold of data-block to determine the diagnostically importance of the block, and designs a data acquisition system to provide the measured flux leakage signals to the computer logging system. Then we present an incorporated Huffman and wavelet data compression algorithm to compress defect data losslessey and irrespective or health data lossyly. In the paper, MFL inspection data compression schematic diagram utilizing FPGA device and results of applying the new method are also presented. The experiment results indicate the way we present can compress great capacity MFL data with high fidelity and good affect.