The double-threshold method has been widely used in ultrasonic flow measurement to determine time-of-flight (TOF) due to its low cost and ease of implementation. Performance of this method is negatively affected by the cycle-skip phenomenon which occurs frequently under inconstant working conditions, especially varied fluid temperature. This paper proposes a method to suppress the phenomenon to facilitate reliable determination of TOF in ultrasonic flow measurement. First, the double-threshold method is used to generate a feature point to segment the signal. Second, based on the correlation coefficient and signal power, judgement factors of individual signal periods are calculated to determine signal onset. Finally, a valid zero crossing which has a constant lag from the onset is selected to determine the TOF. Thus, the cycle-skip phenomenon is suppressed. Two additional modifications are proposed to eliminate the influence of varied signal frequency and low sampling rate. The proposed method was validated by an experiment based on an ultrasonic water flow sensor. Results showed that the frequently appearing cycle-skip phenomenon can be successfully suppressed by the proposed method.
超声波渡跃时间 (TOF) 的准确检测是超声波流量测量中最重要的一步. 测量环境 (如流体介质、 温度等因素) 的变化, 会导致超声波波形发生变化, 进而引起 TOF 检测的跳波问题, 带来流量测量误差. 本文旨在提出一种 TOF 检测算法, 避免跳波问题的出现.
1. 根据超声波信号的波形特征, 提出了基于单一超声波信号的起振点判定方法, 进而抑制跳波问题的发生; 2. 针对实际应用中常见的频变和采样率低的问题, 提出了优化方法, 使所提方法更具实用性.
1. 依据超声波信号的周期性和幅值特征, 提出单周期信号间相关系数和平均功率相结合的判定因子, 据此对超声波信号进行判定并寻找起振点, 再根据起振点来确定 TOF, 从而抑制跳波问题; 2. 应用基于过零点的信号分割方法和基于 FFT 的信号插值方法, 解决信号频率变化和采样率低带来的实用性问题; 3. 根据超声波信号波形易受温度影响的特性, 利用流量标定台设计并进行相应实验, 使用自制的超声波流量传感器采集大量波形剧烈变化的信号用于计算 TOF, 并与传统方法进行对比, 验证所提方法在抑制跳波问题方面的有效性; 4. 使用标定台在不同温度下对超声波流量计进行标定, 使用不同的 TOF 确定方法, 展示跳波问题对流量计精度的影响, 并对此进行理论分析.
1. 介质温度等因素会影响超声波信号的波形, 进而引起 TOF 检测的跳波问题. 2. 超声波信号在周期性和单周期的平均功率上都与噪声信号有所差异; 所提方法从这两方面出发, 可准确找到信号起振点, 进而抑制跳波问题.
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Barshan B, 2000. Fast processing techniques for accurate ultrasonic range measurements. Measurement Science and Technology, 11(1):45–50. https://doi.org/10.1088/0957-0233/11/1/307
Beck MS, 1981. Correlation in instruments: cross correlation flowmeters. Journal of Physics E: Scientific Instruments, 14(1):7–19. https://doi.org/10.1088/0022-3735/14/1/001
Bravo EC, Bastos TF, Martin JM, et al., 1994. Ultrasonics —temperature shapes the envelope. Sensor Review, 14(4): 19–23. https://doi.org/10.1108/EUM0000000004234
Carullo A, Parvis M, 2001. An ultrasonic sensor for distance measurement in automotive applications. IEEE Sensors Journal, 1(2):143. https://doi.org/10.1109/JSEN.2001.936931
Demirli R, Saniie J, 2001. Model-based estimation of ultrasonic echoes. Part I: analysis and algorithms. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 48(3):787–802. https://doi.org/10.1109/58.920713
Espinosa L, Bacca J, Prieto F, et al., 2018. Accuracy on the time-of-flight estimation for ultrasonic waves applied to non-destructive evaluation of standing trees: a comparative experimental study. Acta Acustica United with Acustica, 104(3):429–439. https://doi.org/10.3813/AAA.919186
Fang ZH, Hu L, Mao K, et al., 2018. Similarity judgment-based double-threshold method for time-of-flight determination in an ultrasonic gas flowmeter. IEEE Transactions on Instrumentation and Measurement, 67(1):24–32. https://doi.org/10.1109/TIM.2017.2757158
Frederiksen TM, Howard WM, 1974. A single-chip monolithic sonar system. IEEE Journal of Solid-State Circuits, 9(6): 394–403. https://doi.org/10.1109/JSSC.1974.1050533
Hoseini MR, Wang XD, Zuo MJ, 2012. Estimating ultrasonic time of flight using envelope and quasi maximum likelihood method for damage detection and assessment. Measurement, 45(8):2072–2080. https://doi.org/10.1016/j.measurement.2012.05.008
Hou HR, Zheng DD, Nie LX, 2015. Gas ultrasonic flow rate measurement through genetic-ant colony optimization based on the ultrasonic pulse received signal model. Measurement Science and Technology, 26(4):045005. https://doi.org/10.1088/0957-0233/26/4/045005
Jiang YD, Wang BL, Huang ZY, et al., 2017. A model-based transit-time ultrasonic gas flowrate measurement method. IEEE Transactions on Instrumentation and Measurement, 66(5):879–887. https://doi.org/10.1109/TIM.2016.2627247
Li WH, Chen Q, Wu JT, 2014. Double threshold ultrasonic distance measurement technique and its application. Review of Scientific Instruments, 85(4):044905. https://doi.org/10.1063/1.4871993
Lu ZK, Yang C, Qin DH, et al., 2016. Estimating ultrasonic time-of-flight through echo signal envelope and modified Gauss Newton method. Measurement, 94:355–363. https://doi.org/10.1016/j.measurement.2016.08.013
Lynnworth LC, Liu Y, 2006. Ultrasonic flowmeters: half-century progress report, 1955–2005. Ultrasonics, 44(Sl): e1371–e1378. https://doi.org/10.1016/j.ultras.2006.05.046
Lyons RG, 2004. Understanding Digital Signal Processing, 2nd Edition. Prentice Hall PTR, Upper Saddle River, USA, p.678–681.
Rajita G, Mandal N, 2016. Review on transit time ultrasonic flowmeter. The 2nd International Conference on Control, Instrumentation, Energy & Communication (CIEC), p.88–92. https://doi.org/10.1109/CIEC.2016.7513740
Roosnek N, 2000. Novel digital signal processing techniques for ultrasonic gas flow measurements. Flow Measurement and Instrumentation, 11(2):89–99. https://doi.org/10.1016/S0955-5986(00)00008-X
Sabatini AM, 1997. Correlation receivers using Laguerre filter banks for modelling narrowband ultrasonic echoes and estimating their time-of-flights. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 44(6):1253–1263. https://doi.org/10.1109/58.656629
Sunol F, Ochoa DA, Garcia JE, 2019. High-precision time-of-flight determination algorithm for ultrasonic flow measurement. IEEE Transactions on Instrumentation and Measurement, 68(8):2724–2732. https://doi.org/10.1109/TIM.2018.2869263
Tezuka K, Mori M, Suzuki T, et al., 2008. Ultrasonic pulse-Doppler flow meter application for hydraulic power plants. Flow Measurement and Instrumentation, 19(3–4): 155–162. https://doi.org/10.1016/j.flowmeasinst.2007.06.004
Wu J, Zhu JG, Yang LH, et al., 2014. A highly accurate ultrasonic ranging method based on onset extraction and phase shift detection. Measurement, 47:433–441. https://doi.org/10.1016/j.measurement.2013.09.025
Zheng DD, Hou HR, Zhang T, 2016. Research and realization of ultrasonic gas flow rate measurement based on ultrasonic exponential model. Ultrasonics, 67:112–119. https://doi.org/10.1016/j.ultras.2016.01.005
Zhu WJ, Xu KJ, Fang M, et al., 2017. Variable ratio threshold and zero-crossing detection based signal processing method for ultrasonic gas flow meter. Measurement, 103: 343–352. https://doi.org/10.1016/j.measurement.2017.03.005
Cheng-wei LIU, Ze-hua FANG, Liang HU, Yong-qiang LIU, Rui SU, and Wei-ting LIU declare that they have no conflict of interest.
Project supported by the Science Fund for Creative Research Groups of National Natural Science Foundation of China (No. 51821093)
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Liu, Cw., Fang, Zh., Hu, L. et al. A method to avoid the cycle-skip phenomenon in time-of-flight determination for ultrasonic flow measurement. J. Zhejiang Univ. Sci. A 22, 695–706 (2021). https://doi.org/10.1631/jzus.A2000284
- Ultrasonic flow measurement
- Time-of-flight (TOF)
- Correlation coefficient
- Signal power
- Double-threshold method