小波变换在行驶车辆检测器中的应用

Application of Wavelet Transform in Running-vehicle Detectors

为提高环形线圈对行驶车辆的检测精度,针对车辆检测器输出信号的处理问题,通过建立车辆高速通过环形线圈时频率变化曲线的数学模型,并对测量信号进行小波变换分析,不但能滤除噪声信号,而且能很好地保留信号的突变部分,体现不同车辆经过车辆检测器时的信号特征。采用小波多尺度分析提取信号高频细节系数和小波能量分布系数,可以从细节系数及能量分布中获得车辆通过环形线圈的准确特征,从而建立能量分布分析的小波变换后处理方法。大量试验结果表明,采用小波变换方法分析车辆通过环形线圈时频率变化信号,能很好地体现测量信号中的奇异值并显著提高车辆检测效果。

In order to improve the detection precision of circle loop to running-vehicles, for signal processing of vehicle detector, through constructing the mathematical model of frequency variation curve when vehicles at high-speed passing a circle loop, and using wavelet transform to analyze the measured signals, not only the noise signals is filtered, but also the mutant signals is retained and the signal characteristics is reflected when a variety of vehicles passing the circle loop. High frequency detail coefficients and wavelet energy distribution coefficient are extracted based on wavelet multi-scale analysis, the accurate characteristics are acquired from detail coefficients and energy distribution when vehicles passing the circle loop, and the wavelet transform post-process method of energy distribution analysis is established. A large number of experimental results show that it could reflect the singular value of measured signals and remarkably improve vehicle detection effect based on wavelet transform method to analyze the frequency variation signal when vehicles passing circle loop.