Study And Design On Multiple Gases Analysis System Based On Artificial Neural Network

It is went without saying that the sensor is very important to the information systems. The sensor's characteristics and the reliability of the output are mostly significant to the whole system's quality. The improvement of the automatization level in every field of life, especially the improvement of the automatization level in industry production requires higher performance of the sensor. Because of the gas sensor's physical shortcoming such as its cross sensitivity, a single gas sensor can't accomplish the multiple gases' qualitative identification and quantitative detection. With the development of intelligent theory and technology ,intelligent gas consisting of gas sensor array and artificial neural network is excogitated, which achieve the intelligent detection of multiple gases.Along with the development of petrochemistry industry and improvement of people's standard of living, combustible, explosive and poisonous gases' category and use sphere have an increase at the same time .Once these gases are leaked out when they were in the course of production, transportation and use ,will induce poisoning ,fire and explosion accident and jeopardize the security of people's life and belongings. So, it is valuable to exploit such an instrument that can analyze multiple gases .In this paper ,based on the theory of electronic nose, we study a kind of multiple gases analysis system, consisting of gas sensor array and artificial neural network, which using gas sensor array's multidimensional response mode for multiple gases to accomplish the identification of different gases .This multiple gases analysis system has more selectivity, and resolves the selective problem that the single gas sensor can't resolve.The multiple gases analysis system based on artificial neural network mainly consists of gas sensor array ,signal detection module and signal processing module three parts. This paper involves the technology of sensor, Single Chip Micyoco ,serial interface communication ,signal preprocessing ,algorithms of Back Propagation network and pattern recognition.Gas sensor is the kernel of gas sensor array and the most significant component of multiple gases analysis system .Its level of selectivity, reiteration and cross sensitivity will affect the whole system's quality directly .The introduce of gas sensor theory and MQ series gas sensor array provide the basic measure condition for design of detection circuit and signal processing. The signal detection system based on RS-232C standard fulfills the diversion of gas sensors' analog signals to computer's digital signals and digital signals' storage ,and provides the standard datasheet for pattern recognition and emulational algorithms.The signal processing module is the most significant part of the system to complete the multiple gases' analysis .Its characteristics mainly affect the precision of gases' detection.The theory model of the multiple gases analysis system, algorithms of Back Propagation network, design of ANN based on MATLAB neural network toolbox are discussed firstly .Then described the detection ways in multiple gases identification in order to validate the system's feasibility .Qualitative and quantitative analysis experiments of three kinds of gases are completed with gas sensor array combined with pattern recognition. The experiment includes: signal preprocessing algorithms; ANN design, number determination of the input layer, output layer and the hidden layer of the BP network; train of the neural network and analysis of the results. Through the experiment, the system designed achieved 100% in qualitative analysis of three gases and low error in quantitative analysis ,which validated the system's feasibility. Deviation analysis and suggestions for improving the system's performance have some application value for engineering.