Design And Key Algorithm Research Of Precision Ultrasonic Gas Flowmeter

With the progress of human society and the rapid development of science and technology,the demand for precise measurement of gas flow in daily life,industrial,agricultural production,import and export trade and other fields has become more and more urgent.In a variety of flowmeter schemes,ultrasonic schemes have been widely used with their unique advantages,but due to complex technology,coupled with the early advantage of foreign countries,current domestic precision ultrasonic gas flowmeter market is almost monopolized by foreign companies,and the core technology is strictly confidential,therefore,it is quite vital to carry out domestic ultrasonic gas flowmeter and its algorithm research with independent intellectual property rights.This paper uses Xilinx’s Zynq series SoC as the main control chip to design ultrasonic gas flow meter.Using the time difference method as the basic measurement principle,the accurate positioning of characteristic waves is analyzed and researched in depth based on the single-channel measurement method.In the process of hardware design of the flow meter,the ultrasonic excitation signal amplification circuit,receiving signal multipleselection circuit,adjustable gain control circuit,and AD conversion circuit were designed around the main control chip.In addition,hardware circuits such as multiple power supply circuits,temperature acquisition circuits,HMI interface circuits,and NB-IOT interface circuits were designed as needed,too.Giving full play to the advantages of Zynq’s PS+PL integrated architecture,functions of ultrasonic excitation signal generation,echo signal acquisition,band-pass filtering,data storage and other functions were implemented in the PL(Programmable Logic)part;while the characteristic wave detection algorithm is implemented in PS(Processing System)section.High-precision replay time of the forward and reverse flow can be calculated based on the collected data,and the flow rate flow data can be calculated,in addition to the data exchange program with the NB-Io T module and the data communication program with the HMI module.Finally,the design of the software and hardware circuits of the practical ultrasonic gas flow meter was completed successfully.In order to verify the performance of gas flow meter,FDM(Fused deposition modeling)technology was used to make the prototype shell,and the prototype was subjected to long-term functional debugging and performance testing.Experimental results confirmed that the measurement results were accurate and reliable,and the measurement accuracy of ultrasonic TOF time could reach 0.1us,besides,it’s robust for different temperature and humidity environment.