Real-time Data Acquisition And Control System For Remote Sensing Detection Of Automobile Exhaust

With the continuous increase of automobiles in China,automobile exhaust has become the main source of air pollution.As one of the important causes of urban air pollution and photochemical pollution,automobile exhaust directly affects human health.In order to realize the effective management of automobile exhaust emissions and set standards of the identification and control of automobile emissions,it is necessary to detect the exhaust emissions of automobile effectively.The detection objects of automobile exhaust remote sensing equipment includes CO,CO₂,NO,HC and PM（particulate matter）,which uses different detection technologies and devices.CO and CO₂are detected using FM-TDLAS（frequency modulation tunable diode laser absorption spectroscopy）,the detection of NO,HC is used DOAS（differential optical absorption spectroscopy）,and the PM is detected by using smoke opacity technology,So the data acquisition and control system in automobile exhaust remote sensing needs to collect multi-channel analog signals and digital signals,and some control functions should to be taken into account.In addition,the system needs to obtain the detection data in a short diffusion time of tail gas,which requires high real-time performance.A real-time data acquisition and control system for remote sensing detection of automobile exhaust is designed in this paper.PIC24FJ256GB210 and ds PIC30F6014A microcontrollers are used as dual cores,external high-precision A/D is used for analog-to-digital conversion and collects infrared absorption spectrum data in this system.The ultraviolet spectrum data are obtained by using USB communicate with the spectrometer of the DOAS subsystem.The green light intensity data of the smoke opacity subsystem is collected by the internal A/D of the PIC24FJ256GB210 microcontroller,and then the TCP/IP communication is carried out with the industrial computer through the W5500 module.In addition,the control function of each subsystem is taken into account.The real-time data acquisition and control system guarantees the real-time performance through reasonable task allocation of dual-core,introduction of lightweight real-time operating system Free RTOS and reasonable priority settings for multi-tasks.This system is installed in the remote sensing equipment of automobile exhaust gas.The test results show that a set of detection data including infrared absorption spectrum,ultraviolet spectrum and opacity green light intensity can be uploaded infallible within 45ms.Then time spent is still far below the 1s required when several sets of data are transmitted at the same time.The detection error of the pollutant gas concentration is far lower than the requirements of the relevant national regulations.It is verified that the data collection and transmission,control functions and real-time performance of the system all meet the design requirements.