Weighing Module Design Research Based On The Technology Of SAW

In recent years,fine particulate matter PM2.5 more and more affect the quality of human life.In order to effectively prevent and control PM2.5,need to be arranged in the field of multiple monitoring instruments for its sampling and analysis.The first step in sampling analysis is to measure the concentration of PM2.5 in the atmosphere.Usually the before and after the sampling of the media to be weighed.The difference between the quality of the sampling and the volume of the sampling is the sampling concentration.Because the field environment is bad,the traditional PM2.5 weighing method can not meet the requirements,so the new PM2.5 weighing method is the key to ensure accurate sampling.Surface acoustic wave(SAW)is a kind of elastic wave,the characteristic is spread along the shallow surface of the solid.SAW sensor is a material science and electronic technology products,it has passive,wireless and anti-jamming characteristics.The SAW pressure sensor uses a surface acoustic wave oscillator to sense the disturbance of the external force field,to change the SAW oscillation frequency,and to measure the pressure variation by accurately measuring the frequency change.Based on the acoustic surface wave pressure sensor automatic weighing program is researched and designed in the paper.It is the part of airborne particles automatic monitoring technology and device.The main contents of this paper are as follows:1.The principle and performance of SAW pressure sensor are researched.The SAW pressure sensor type suitable for airborne particle weighing is selected.The main technical indexes include SAW device structure is resonator structure,SAW device base is quartz crystal,in order to avoid the effect of temperature so the form of a dual channel type oscillator structure is chosen.2.The data acquisition and analysis program based on LabVIEW2014 and the single chip microcomputer is designed.The collected data can be observed more intuitively and the working performance of the weighing module is analyzed.The communication problem between the MCU and PC is solved and the feasible communication scheme is put forward.3.The program of air fine particle weighing data processing based on Kalman filter is designed.The validity of the algorithm is proved by Matlab simulation.The disadvantage of weighing data acquisition is affected by the external environment and measurement error and interference are overcome.4.The whole system experiment is designed.And the follow-up technical part related to the weighing of fine particles is detailed designed.A schematic diagram of an automatic weighing module consisting of servo motors,lift arms,filter paper,filter shelves,locating blocks,weighing rods,load cells and brackets.Finally,combined with the measured data of the weighing module.The feasibility of the weighing module is verified.The SAW technology in the application of fine particles in the weighing of the preliminary study in the paper,will be lay a certain foundation for the future of PM2.5 field test equipment development of China.