The Research Of Detection And Control System For Indoor Harmful Gas

Indoor environmental quality(IEQ) is very important to people’s health, which not only reflects in the temperature and humidity, but reflects in the concentration of harmful gases(formaldehyde, ammonia). Due to the restriction of economic development level, at present the development of the indoor environment monitoring technology is relatively backward in our country.Although the degree of automation of existing indoor monitoring system is improved, the accuracy and anti-interference ability are difficult to guarantee which often appears false positives and misstatement and can not efficiently and accurately analyze the overall quality of indoor environment.In view of the influence of indoor formaldehyde, ammonia, temperature and humidity on people’s health, a real-time online monitoring system which can detect and control gas concentration,temperature and humidity is designed. The lower computer of the system is based on STM32F103 microcontroller and sensor and the upper computer interface uses Visual Basic6.0 to develop, the information of the two exchanging and communicating by RS-485. Using the median and average filtering algorithm, the system can effectively filter out interference components of sensors in the process of collecting signal. Put forward two kinds of multisensor data fusion algorithm based on adaptive weighted and fuzzy set theory. Adaptive weighted data fusion can not only make full use of the original data of the sensor to fuse the mean square error and the measuring accuracy and other information, but achieve the optimal fused data on the premise of general minimum variance. Because the degree of indoor various factors influencing on the physical health is different, using the weight vector of the decision level data fusion based on the fuzzy set theory can more clearly understand the quality of the indoor environment.Through the system testing, the results show that people can not only timely understand the current value and quality level of indoor formaldehyde, ammonia, temperature and humidity, but also be easier to look indoor comprehensive quality level after fusion and the operational state of the system through the monitoring interface humanization. Every indicators of the system has reached the expected requirement which has strong anti-interference ability and high credibility.