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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 accuracy of the loop coil on the traveling vehicle, aiming at the problem of the output signal of the vehicle detector, by establishing the mathematical model of the frequency curve of the vehicle passing the loop coil at high speed and carrying out the wavelet transform analysis on the measurement signal, Signal, and can well retain the sudden change part of the signal, reflect the signal characteristic when different vehicles pass the vehicle detector. Using wavelet multi-scale analysis to extract high-frequency signal detail coefficients and wavelet energy distribution coefficients, accurate characteristics of the vehicle passing through the toroidal coil can be obtained from the detail coefficients and energy distributions to establish a wavelet transform post-processing method for energy distribution analysis. A large number of test results show that the use of wavelet transform method to analyze the frequency change signal of the vehicle passing through the toroidal coil can well represent the singular value of the measured signal and significantly improve the detection effect of the vehicle.