Research On Liquid Concentration Measurement System Based On Ultrasonic Wave

At present,traditional industrial mode is developing towards intellectualization.High precision measurement of liquid concentration has attracted more and more attention in processing industry.The results of this paper can provide a complete solution for real-time online concentration measurement in the industrial field and strong theoretical guidance and technical support for ultrasonic application in industrial measurement.At the same time,it provides detection technology of physical layer for current industry 4.0,theoretical basis for real-time measurement of liquid environment concentration and development of industrial field intelligent instrument.In this paper,a high-precision concentration measurement study based on ultrasonic wave is carried out to analyze the formation of acoustic velocity measurement error and explore the digital signal processing method.High accuracy measurement of sound velocity is realized by improving the algorithm of sound velocity measurement so as to provide reliable sound velocity data for ultrasonic liquid concentration measurement.In concentration modeling process,multi-parameter fitting method is explored based on the correlation among in sound velocity,temperature and concentration.Then,improve the goodness of fitting of the concentration measurement model and achieve the high-precision measurement of concentration.Specific research contents are as follows:1.We design ultrasonic sound velocity measurement device and ultrasonic concentration measurement device according to the demand of measurement of sound velocity and concentration data.The sound speed measuring device realizes data transmission of local area network,which provides a good application scheme for the on-line data acquisition.It can display the waveform in the process of ultrasonic transmission and store signal data in real time.2.The measurement system based on ultrasonic wave realizes real-time acquisition of dual-channel ultrasonic signal by using FPGA+C8051 single chip computer.Using Ultrasonic Transducer to realize Ultrasonic Propagation in liquid to be measured,and complete entire system workflow by using filter processing,analog to digital processing,DPRAM data storage processing,EMIF data transmission processing etc.It provides a hardware platform for verification of sound velocity measurement algorithm and concentration measurement algorithm.3.Study on acoustic velocity measurement algorithm based on ultrasonic wave: Using time-domain cross-correlation method and frequency-domain phase difference method to realize measurement of sound velocity in liquid based on traditional method of acoustic velocity measurement.Accuracy of sound velocity measurement is further compensated on basis of error measurement in hardware circuit,so as to provide high-precision sound velocity data for subsequent concentration measurement.Whole-period flight time was measured by time-domain correlation method,phase difference of signal was calculated by FFT,and stability and reliability of sound velocity measurement of ultrasonic system were improved according to the time-frequency mutual feedback mechanism.4.Research on Measurement algorithm of liquid concentration based on Ultrasonic Wave: The key of ultrasonic liquid concentration measurement lies in reliability of calibration data and the size of data.In the existing equipment and measurement platform,using surface fitting algorithm to model and analyze correlation between temperature,sound velocity and concentration.Through data preprocessing,data interpolation,model fitting and model selection,concentration measurement model is constructed.Finally,weight coefficient is extracted by the constructed model,which can be used to measure liquid concentration online in real time.