Design Of Distributed Acoustic Sensor System For Mine

Due to the narrow underground space,complex environment and numerous equipments,all kinds of unexpected coal mine accidents are extremely destructive,which can cause complete collapse of the underground power supply system,and it is difficult to sustain the long-term rescue process due to the standby power supply.The personnel positioning system and the communication contact system cannot work normally,making it difficult for the rescue team to locate the trapped person in time.Therefore,in order to improve the safety production level of coal mines and reduce the mortality rate of mine accidents,this paper has developed a mine distributed acoustic sensor that can perform passive emergency rescue positioning for trapped underground personnel in response to the uncharged environment after a major underground mine accident.Systematic research provides a new solution and a suggestion for the development of coalmine emergency rescue technology.The main work completed in this paper is as follows:(1)The fiber acoustic sensing mechanism is studied,and the acoustic detection system scheme of the Sagnac and Mach-Zehnder composite structures is designed,and the sound signal acquisition,time and frequency domain signal display,frequency domain signal function fitting,wide frequency impact signal zero frequency positioning and other functions is realized in the mining distribution optical fiber acoustic sensor system using LabVIEW graphical programming software.(2)In order to realize the integration of acoustic detection system,a dual channel mine microphone embedded module scheme was designed.The STM32 microcontroller was used to realize the control of the two-way mechanical optical switch,signal acquisition and display.The user image interface library of the FreeRTOS system and STemWin were used to develope a human-computer interaction interface for embedded acoustic sensing systems for channel switching and waveform adjustment.(3)Aiming at the problem that the traditional null-frequency localization algorithm is only applicable to wideband signals,a sound localization algorithm based on adjustable optical fiber delay line technology is proposed.By comparing the difference between incremental and high-precision continuously adjustable optical fiber delay lines selected the program.With the Matlab software,the simulation and experimental verification of positioning results is realized with different characteristic frequencies.(4)A composite structure sound detection system of Sagnac and MachZehnder was built to perform time domain acquisition and spectrum analysis of a 200Hz-2kHz tone signal,verifying that the detection system has uniform spatial directivity in the horizontal plane The frequency detection accuracy of the signal was tested.At the same time,human-machine interface display control and debugging were carried out on the dual-channel embedded microphone system,and experiments such as dual-channel switching collection of call voice and Moss code sound were implemented,and the system resistance noise performance analysis was implemented under the influence of mining scraper noise.The proposed fiber delay line location algorithm has been experimentally verified and can locate both broadband signals and single tone signals with a positioning error within ±70m.The mining distributed acoustic sensing system proposed in this paper can be used in the post-disaster non-electricity environment,and the functions of the existing coal mine emergency rescue system can be supplemented and perfected,so that it can be promoted in all kinds of mine emergency rescue areas.