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为了消除速度测量中的方向模糊以及减小测量不确定度,建立了一套基于空时滤波器的新型空间滤波测速仪。设计了一种基于高速互补金属氧化物半导体(CMOS)线阵图像传感器的空时滤波器,并从理论上分析了该类型空时滤波器的滤波特性。采用了快速傅里叶变换法分析输出信号的频谱,并通过能量重心法对频谱进行校正,减小了频率测量不确定度。使用这种新型测速仪对传送带的平移速度进行了测量。实验验证了该空时滤波器对运动方向辨别的可行性。同时,通过实验还分析了速度测量相对标准不确定度。实验结果表明使用空时滤波器的空间滤波测速仪可以使速度测量相对标准不确定度在频率测量相对标准不确定度的基础上大大降低。降低后的速度测量相对标准不确定度小于0.24%,该值还可以通过合理选择空时滤波器的参数来进一步减小。
In order to eliminate the ambiguity of the speed measurement and reduce the measurement uncertainty, a new spatial filter velocimeter based on the space-time filter was established. A space-time filter based on high-speed complementary metal oxide semiconductor (CMOS) line image sensor is designed and the filtering characteristics of this type of space-time filter are theoretically analyzed. The fast Fourier transform method is used to analyze the frequency spectrum of the output signal, and the spectrum is corrected by the energy centroid method to reduce the frequency measurement uncertainty. The conveyor speed was measured using this new speedometer. The feasibility of this space-time filter to identify the direction of motion is verified experimentally. At the same time, the relative standard uncertainty of speed measurement is also analyzed through experiments. The experimental results show that the spatial filter velocimetry with space-time filter can make the relative standard uncertainty of velocity measurement greatly reduced based on the relative standard uncertainty of frequency measurement. The relative standard uncertainty of the reduced speed measurement is less than 0.24%. This value can be further reduced by a reasonable choice of the parameters of the space-time filter.