The Research Of Mine Active Noise Control Technology Based On FXLMS Algorithm

Noise is one of the main occupational hazard in mine.The characteristics of coal mine noise is low frequency outstanding, big strength, interfere with the long time, strong penetrability etc. In recent years, As the law of The occupational disease prevention law of the People’s Republic of China and The discharge standard of noise at boundary of industrial enterprises carried out, it is paid attention to noise hazards of coal mine gradually in China. It is obvious that the traditional noise control technology to reduce high-frequency noise, but it is not obvious that the traditional noise control technology to reduce low frequency noise.However, active noise control technology is a remedy to the traditional noise control technology, because active noise control technology havs good low frequency noise reduction features.Therefore, it is significan fort developing practical value active noise reduction earmuffs that we are research active noise control technology in coal mine.In this paper, bsed on analysis of active noise reduction technology status and coal mine noise source and noise characteristics,the active noise control technology that is based on FXLMS adaptive noise reduction algorithm is studied for the low frequency noise in coal mine. It is mainly determined by convergence speed, steady-state error and the computation of three factors for FXLMS algorithm performance, and mutual restraint between the three. Due to the noise density in coal mine, it is lead to the algorithm computational complexity and slow convergence speed.However, convergence coefficient μ is not only a very important content for FXLMS algorithm but also he key to the optimization design. It is not only increased the convergence rate of the FXLMS algorithm but also reduce the amount of arithmetic operation and steady-state error by selecting different convergence coefficient in the steady-state error of different stage. Based on this, the secondary path modeling has been established by using offline modeling method and verify the convergence of the simulation. The Active Noise Control System has been built by selecting DSP chip, ADAU1772 processors. Moreover, it carried out mono noise simulation experiment of the 1 kHz sine signal, which is representative in the low frequency noise in coal mine. In addition, it carried out mixed noise simulation experiment of the 1 kHz sine signal adding the interference noise, which energy is 20% of the tone signal.I collected KCS 250 mine wet dust noise data and made noise simulation experiment, I verified the noise reduction effect of the designed active noise control system.By our studying, obtained the following conclusions:(1) Convergence coefficientμis a very important content for FXLMS algorithm, because its value determines whether the adaptive process of convergence, and its value determines the convergence speed and the size of the steady-state error of the adaptive process;(2) The secondary channel model based on FXLMS algorithm optimization design simulation results show that fitting the normalized energy secondary channel curve and measured curve deviation error is less than 0.05,and phase difference about 40 degrees. It is show that optimization design meet the desired requirements and the secondary channel model is stable;(3) It can reach 30 dB for 1 kHz sine signal tone noise reduction by designed active noise control system. To join interference noise sine signal, it can reach 30 dB too. Therefore, Interference noise has no effect on sine signal noise reduction;(4) It is accurate and reliable to noise frequency collect data by the designed active noise control system. The fundamental frequency of measurement is about 680 Hz for KCS250 mine wet dust collector. Differ is less than 0.5% with the theoretical calculation of filter frequency 677 Hz;(5) It can achieved 5～6 dB for KCS250 mine wet precipitator noise reduction by desiged active noise control system.