Detecting of Coal Gas Weak Signals Using Lyapunov Exponent under Strong Noise Background

In coal gas monitoring system, the early detecting of gas concentration is key technique for preventing the gas explosion because the coal gas signals are very weak under strong noise background in mining digging laneway. In this paper, the coal gas chaotic characteristics of the mine underground are analyzed, the Lyapunov exponent is used to judge the chaotic characteristic of gas weak signal as the criteria for chaos. The principle using the Lyapunov exponent for the detecting gas weak signals based on chaos theory is presented, and the model of Duffing chaotic oscillator for the coal gas monitoring system is established. The phase space of chaotic time series of coal gas is reconstructed. Threshold value of coal gas chaos detection system is determined based on Lyapunov exponent. Simulation results verify the validity of this method for early detecting weak coal gas signals under strong noise background in the coal gas concentration monitoring system.