Design of vibration sensor for coal gangue identificatio
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摘要: 目前自动化放顶煤开采煤矸识别技术中,伽马射线成本太高且对人体有害;红外技术受环境温度影响较大;雷达探测在煤层较厚时信号衰减严重;声音技术成本低、难度小,但受外界声音信号干扰严重;图像技术在煤矸颜色差别大时有效,但受粉尘、光线因素影响较大;振动技术具有声音技术的优点,同时又可以避免环境噪声干扰,具有较高的检测精度。顶煤和矸石的性能有所不同,落到液压支架尾梁上时产生的振动信号也表现出不同的特征。针对该特征,设计了一种振动传感器,该传感器安装在液压支架尾梁的腹板处,对顶煤或矸石砸到液压支架上产生的振动信号进行感知,通过信号处理和分析辨识出放煤过程中的煤块和矸石。该传感器利用加速度计采集尾梁振动信号,并对采集数据进行前端滤波处理;利用傅里叶变换对数据进行功率谱分析,得到单位时间内的最大振动频率、幅值及功率谱能量。实验室测试结果表明,该传感器测量误差在1%以内。井下测试结果表明,振动传感器采集的信号大部分是煤块落下时的振动信号,其频率范围为100~200 Hz,而矸石落下时的振动信号频率在200 Hz以上,根据振动信号特征能够识别出顶煤和矸石。Abstract: At present, there are a variety of coal gangue identification technologies in automatic top coal mining. Gamma ray is too expensive and harmful to human body. Infrared technology is affected by ambient temperature. Radar detection has serious signal attenuation when the coal seam is thick. Sound technology has low cost and small difficulty, but can be severely interfered by external sound signals. Image technology is effective when the color difference of coal gangue is large, but is affected by dust and light factors. However, vibration technology not only has the advantages of sound technology but also can avoid environmental noise interference and obtain a higher detection accuracy. For the properties of top coal and gangue are different, the vibration signal generated when falling onto the hydraulic support tail beam also shows different characteristics. Based on this feature, a vibration sensor is designed, which is installed at the web of the tail beam of the hydraulic support to sense the vibration signal generated by the top coal or gangue hitting the hydraulic support, and identify the coal and gangue in the coal release process through signal processing and analysis. The sensor uses an accelerometer to collect the tail beam vibration signal, and conducts front-end filtering processing of the collected data. Fourier transform is applied to analyze the power spectrum of the data so as to obtain the maximum vibration frequency, amplitude and power spectrum energy per unit time. The laboratory test results show that the sensor measurement error is within 1%. The underground test results show that most of the signals collected by the vibration sensor are the vibration signals of coal falling, and the frequency range is 100-200 Hz. However, the vibration signals of gangue falling is above 200 Hz. Therefore, the differences of the vibration signal characteristics are useful to identify the top coal and gangue.
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