The Design Of Digital Air Sampler

Atmospheric sampling instrument is this instruments or device which is used to collect the polluted air. In recent years,the atmospheric sampling instrument become the environmental monitoring field of an important component. This paper describes in details a at present more popular sampling gas velocity measurement method, That is, through calculating sampling instrument mini vacuum pump which brings the dc motor speed and current, thus we can obtains flow rate. And based on the method this paper design a new digital atmospheric sampling instrument with simple operation, low cost, low consumption characteristics.This paper mainly introduces the ideas from two aspects, including sampling instrument design of hardware circuit and software design. The instrument itself mainly include mini vacuum pump, SCM, rotary speed and A/D acquisition circuit and D/A transformation circuit, LCD monitor and keyboard. Putting through power supply, the instrument users start the sampling switch through pressing set key, Motor speed and A/D acquisition circuit accurately measure motor speed and current, and finish by analogue to digital quantity of conversion.Through the monolithic integrated circuit finish the feedback control to mini vacuum pump with dc motor of the current, finally finish the digital quantity to analogue conversion by D/A transformation circuit. Finally this instument controls gas velocity size, and it can displaye the gas velocity size on LCD. Software in a nutshell,this paper adopte two-dimensional piecewise linear interpolation algorithm and use fuzzy control algorithm to control the sampling velocity.