Research Of Vehicle Noxious Gas Detection Basing On Metal Oxide Semiconductor Sensor

In recent years, various kinds of technical measures for gas detecting have become more and more comprehensive and application of gas examination has changed widely, along with attention of environmental consciousness as well as to the life health, that causes people to be getting more and more common to the environmental pollution gas examination of vehicle and the indoor virulent organic volatility gas pollutant examination. As the gas sensor being applied gradually, people pay more attention to the selectivity, the accuracy, and the stability of the gas sensor. The metal oxide semiconductor sensor is applied widely for its low cost and relatively high sensitivity.The key parameters of gas sensor performance are the sensitivity, selectivity, and stability, especially the selectivity and the sensitivity for the semiconductor sensor. It still needs further improvement in order to be used in the practical application. We put forward the logarithm model of semiconductor sensor gas detection basing on experiment data; also we infer the analysis formula model of detecting mixture gas gotten from single gas detection model. This article introduces the characteristic model of the metal oxide semiconductor sensor and the analysis inference according to the related sensor characteristic. The paper go through the metal oxide compound sensor's principle structure and the sensitive characteristic, analytical study the sensor examination sensitive analysis, analyse the cross sensitivity model of multi-gases, caused the application semiconductor oxide gas sensor to measure multi-gases ability in vehicle. The design system carry on the gathering control input signales of the multi-channel sensores, and outputs of the system and alarm of system at the same time, has ability with analysis multi-channel component output of the system processing truly. In the aiming next generation vehicle the ambient air quality examination and the control system, its characteristic uses the modular design, has the high intellectualization, may realize the self-correcting just and the network function, has the standard interface, to be possible to exchange, to use in passable the different automobile system. The present paper has also analyzed this kind of sensor's drift compensation characteristic, and fused the system treating processes to realize the system self-correcting ability.As analyzes in above, for the several kind of virulent harmful gas of vehicle and alcohol which causes liquor drives and so on, take the examination object, with TGS2442 (CO), TGS813 (alcohol), TGS2600 (air quality detectioin) and so on, semiconductor sensors take signals to input of system, and system uses the multi-gas model to get concertrationes of multi gases, the intelligent automobile examination system makes a good performace of gathering analysis progress. On the hardware, the metal oxide semiconductor gas sensor detectes the resistance signals of vehicle, CO, ethyl alcohol, and organic matter and so on, transforms their values to the voltage data, the system detection chip is taken by TI Corporation's THS1206 A/D chip, it has the ability of simultaneous working four group analog input, saves A/D amount of use, the slewing rate is very quick, the data processing and the control core is taken by ALTEAR Corporation's FPGA:EP2C20Q240C8, because FPGA processed the data tape in the data processing aspect to be spacious, speed compared to DSP, CPU quicker and so on, the analysis processing fast to the data. Moreover because the carbon monoxide sensor needs the pulse heating, the system also the pulse heating provides by the NE555 chip which accepts FPGA to control and carries on the controllable heating to the sensor, and also the system provide the good serial communication connection with other external connection equipment that general taked by MAX232, might carry on the data exchange with other equipmentes. When some kind of noxious gas will achieve the certainly critical concentration triggering visual display of system alarm warning and will demonstrate the test result.