Design Of Methane Detection Instrument Base On Embedded Technology

The concentration of methane(gas) in Chinese coal mines is higher then in other country, unfortunately, when the concentration in coal mine is at 5%Vol-16%Vol,gas explosion will arise very possibly, so coal mine disasters appear frequently, causing enormous property losing and people casualty, many family getting into rattrap. So it has momentous significance to detect and control concentration of gas accurately and timely. If a instrument can alarm duly when the concentration reach the limit of explosion, people will have enough time to take right measure to prevent the disaster of explosion.For this, in this dissertation, a portable instrument base on embedded technology is designed. In this instrument, a kind of interferometer is used to upbuild a linear relationship between the movement of the interferometer fringes and the concentration of methane. Video camera is used to collect video signal of movement of the interferometer fringes, then this signal is sent into embeded system where digital image procession is done to get the amount of movement of the interferometer fringes, then base on the linear relationship, the concentration of methane is obtained. This instrument has features following:1) using embedded system to process the digital image, avoid the error brought about people's reading the movement of the interference fringes. And at the same time it is made as portable instrument.2) Adopt a temperature sensor to collecting the temperature of the environment, after A/D conversation, it is sent into embedded system, the error cause by environment fluctuations will be expiated in the computer programe.3) The whole system is stably and a simple structure of the gas cell is designed.4) Adopt CMOS video camera for the reason of it's output signal is digital signal, avoid to use video data acqusiation card which will cause the complexity of the instrument and the increase of the cost.5) Use LCD to display the concentration timely, and when concentration meat the limit, electronical element will alarm.6) The detecting systems are characterized as high stability, good explosion preventing capability, long life time etc., and meet the requirements of the issued by the nation.