融合近红外光谱的煤岩界面分布感知研究

Research on coal-rock interface distribution perception based on near-infrared spectra

  • 摘要: 近红外波段反射光谱能够基于煤岩本质物质属性不同所引起的反射光谱特征差异进行煤岩区分,识别精度高,实时性好,但尚未用于煤岩界面位置分布识别。针对采煤机记忆截割在后续截割循环中对煤岩界面自主判定的实际需求,研究了基于近红外反射光谱技术的煤岩界面分布感知技术。采用气煤、炭质泥页岩切割块样搭建了煤壁煤岩界面台架,设计了光纤准直镜−卤钨聚光光源一体式光谱探头并安装于采煤机机身,在采煤机0,3,7 m/s 3种行走速度和光谱探头3,4,5,6 °/s 4种扫描角速度下,测定了煤岩界面附近煤岩的近红外波段(1 000~2 500 nm)后向反射光谱曲线。对于光谱探头在煤壁上每条扫描轨迹中采集的所有反射光谱,在2 150~2 250 nm差异性特征波段,基于余弦距离模糊C均值聚类(CFCM)进行煤岩反射光谱无监督识别,根据每条扫描轨迹上各位置探测结果,基于高度差权重法和扫描轨迹方程确定煤岩界面点理论探测位置。研究结果表明:在采煤机和光谱探头每种运动状态下,光纤准直镜−卤钨聚光光源一体式光谱探头所采集气煤、炭质泥页岩近红外波段后向反射光谱均具有1 400,1 900,2 200 nm附近明显的差异性吸收谷谱带,随着探测入射角增大,煤岩反射光谱曲线均呈下降趋势;同种采煤机行走速度下,随着光谱探头扫描角速度增大,以及同种光谱探头扫描角速度下,随着采煤机行走速度增大,煤岩反射光谱曲线整体均趋于平缓;基于CFCM、高度差权重法、煤壁扫描轨迹方程可实现采煤机和光谱探头运动状态下煤岩界面点的快速精确探测,其中光谱探头3,4,5 °/s 3种扫描角速度下煤岩界面点探测结果的均方根误差不超过1.5 cm,为近红外反射光谱技术应用于煤岩界面分布的精确高效感知提供了参考。

     

    Abstract: Near-infrared reflectance spectra can distinguish coal and rock based on the difference of reflectance spectra characteristics caused by different intrinsic material attributes of coal and rock. This method has high identification accuracy and good real-time performance. But it has not been used for identification of coal-rock interface position distribution. According to the demand for self-determination of the coal-rock interface in the subsequent cutting cycle of shearer memory cutting, the precise distribution sensing technology of coal-rock interface based on near-infrared reflectance spectra technology is studied. A coal-rock interface platform is built by using gas coal and carbonaceous shale cutting block samples. A spectrum detector integrated with optical fiber collimator and tungsten halogen light source is designed and installed on the shearer's body. The near-infrared (1 000-2 500 nm) backward reflectance spectra curves of coal and rock near the coal-rock interface are measured at three walking velocities of the shearer (0, 3, 7 m/s) and four scanning angular velocities of the spectrum detector (3, 4, 5, 6 °/s). For all the reflectance spectra collected by the spectrum detector in each scanning track on the coal wall, the unsupervised identification of coal-rock reflection spectra is carried out based on cosine distance fuzzy C-means clustering (CFCM) in the differential characteristic wave bands of 2 150-2 250 nm. According to the detection results of each position on each scanning trajectory, the theoretical detection position of the coal-rock interface point is determined based on the height difference weighting method and scanning trajectory equation. The research result shows that under each movement state of the shearer and the spectrum detector, the near-infrared reflectance spectra in the backward direction of gas coal and carbonaceous shale collected by the integrated optical fiber collimator tungsten halogen light source spectrum detector have obvious differential absorption valley bands around 1400, 1900, 2200 nm. The reflectance spectra curves of coal and rock all show a downward trend with the increase of the detection incident angle. With the increase of the scanning angular velocities of the spectrum detectors under the same walking velocity of the shearer, and with the increase of the walking velocity of the shearer under the same scanning angular velocity of the spectrum detector, the reflectance spectra curves of coal and rock tend to be flat as a whole. Based on CFCM, height difference weighting method and coal wall scanning trajectory equation, rapid and precise detection of coal-rock interface points under the movement of the shearer and spectrum detector can be realized. Among them, the root mean square error of the detection results of coal-rock interface points under three scanning angular velocities of spectrum detectors 3, 4, 5 °/s is not more than 1.5 cm. The research provides a reference for the application of near-infrared reflectance spectra technology to the precise and efficient perception of coal-rock interface distribution.

     

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