基于自适应阈值的超声波气体流量计设计  

Design of Ultrasonic Gas Flowmeter Based on Adaptive Threshold

作　　者：马勤勇 MA Qinyong(China Coal Technology and Engineering Group Chongqing Research Institute,Chongqing 400039,China)

机构地区：[1]中煤科工集团重庆研究院有限公司,重庆400039

出　　处：《自动化仪表》2021年第4期21-24,共4页Process Automation Instrumentation

基　　金：天地科技股份有限公司科技创新创业基金资助项目(2018-TD-QN057、2019-TD-QN030)。

摘　　要：超声波渡越时间的准确测量是提高超声波气体流量计测量精度的关键。为了避免超声波接收波形幅值抖动引起渡越时间测量出现较大误差,对超声波接收信号处理的硬件电路和软件算法进行了研究。设计了多级滤波放大电路和自动增益控制电路,用于提高超声波接收信号的信噪比和稳定幅值;提出了基于自适应阈值的超声波渡越时间检测方法,根据历史接收波形局部峰值的平均扰动,预测得到新阈值并用于下一周期的渡越时间测量。相对于传统阈值法,自适应阈值法具有更好的抗干扰能力。在音速喷嘴气体流量标准装置上进行了流量标定试验9试验结果证明,该方法具有较高的测量精度和重复性。自适应阈值法不仅适用于超声波流量计,而且可以推广应用于超声波测距和风速风向测量。The accurate measurement of ultrasonic transit time is the key to improve the measurement accuracy of ultrasonic gas flowmeter.In order to avoid the larger error of transit time measurement caused by amplitude jitter of ulrasonic receiving waveform,the hardware circuit and software algorithm of ultrasonic receiving signal processing are studied.The multilevel filter amplifier circuit and automatic gain control circuit are designed to improve the signal-to-noise ratio and stable amplitude of ultrasonic receiving signal.An adaptive threshold based on ultrasonic transit time detection method is proposed.According to the average disturtbance of the local peak of the historical received waveform,a new threshold is predicted and used for the next cycle of lransit time measurement.Compared with the traditional threshold method,the adaptive threshold method has better antiinterference ability.The flow calibration experiment is carried out on the sonic nozle gas flow standard device.The test results show that the method has high measurement accuracy and repeatability.The adaptive threshold method is not only suitable for ultrasonic flowmeter,but also can be extended to ultrasonic ranging,wind speed and direction measurement.

关 键 词：超声波气体流量计 渡越时间 滤波放大 自动增益控制 信噪比 信号处理 自适应阈值 流量标定 

分 类 号：TH814[机械工程—仪器科学与技术]