漏磁无损检测信号相关检测方法研究与仿真分析

Research and simulation analysis on signal correlation detection methods for magnetic flux leakage non-destructive testing

相关检测技术是从噪声中提取有用信号的实用技术。缺陷特征与信号特征密切相关,且呈现对应关系,但在无损检测过程中由于多种因素影响造成信号被噪声强干扰,使信号提取有一定的困难。以正交矢量型数字锁相放大器为核心,通过理论与仿真验证对低信噪比信号相关检测方法进行了研究。首先,基于相关检测的锁相放大技术,并依据相关性原理,进一步研究了正交矢量型数字锁相放大器的检测方案;其次,在该方案的前提下,应用坐标旋转数字计算方法(Coordinate Rotation Digital Computer,CORDIC)来简化复杂的运算,并推导出了反正切值和平方根的计算公式,用于计算低信噪比信号的幅度和相位;最后,通过MATLAB/Simulink进行了建模仿真和误差分析。结果表明,CORDIC旋转算法的计算误差低于1%,该方案的检测误差低于0.3%,检测精度高于99%。

Correlation detection technology is a practical technique for extracting useful signals from noise.The defect features are closely related to the signal features and exhibit corresponding relationships.However,in the process of nondestructive testing,the signal is strongly interfered by noise due to many factors,which makes it dif⁃ficult to extract the signal.Based on the orthogonal vector type digital phase-locked amplifier,correlation detection methods of low signal-to-noise ratio signal is studied by theoretical and simulation verification.Firstly,based on the correlation detection technology of phase-locked amplifier,and according to the correlation principle,the detection scheme of orthogonal vector digital phase-locked amplifier is further studied.Secondly,under the premise of this scheme,the CORDIC rotation algorithm is applied to simplify complex operations,and the formula of inverse tangent value and square root is derived to calculate the amplitude and phase of low signal-to-noise ratio signal.Finally,the modeling simulation and error analysis are conducted by MATLAB/Simulink.The results show that the calculation error of the CORDIC rotation algorithm is less than 1%,the detection error of this scheme is less than 0.3%,and the detection accuracy is higher than 99%.