基于加速度计的顶煤运移时间测量系统

Top coal migration time measurement system based on accelerometer

  • 摘要: 多轮顺序记忆放煤工艺能够改善综采工作面的顶煤采出率和含矸率,但在现场应用中需要对每一轮放煤时间进行精确测定与控制。基于顶煤运移跟踪仪的自动化放煤技术在实际应用中顶煤运移跟踪仪仅作为标志点安置于顶煤中,无法获得更多的顶煤运移信息。针对上述问题,基于顶煤运移跟踪仪,设计了一种基于加速度计的顶煤运移时间测量系统,该系统包括标签、采集器及中心计算机3个部分。标签放置于顶煤内部,放煤过程中跟随顶煤运动,通过内置的加速度计实时采集比力值数据,并调用时间测量算法,实现顶煤运移情况监测,进而确定不同放煤阶段,计算得出不同阶段的顶煤运移时间信息;当标签从放煤口放出后,与刮板输送带产生碰撞,通过射频信号将顶煤运移时间信息向外发送给采集器,通过现场总线进一步传输至中心计算机,指导综采工作面现场实现多轮顺序放煤。详细介绍了顶煤运移时间测量标签的软硬件设计,实现了比力值实时采集、无线信号传输、数据存储等功能;搭建了以3D转台为核心,Gauss-Newton方法为标定算法的标定平台,完成了加速度计的标定工作,标定后的加速度计能够准确采集顶煤运移时间测量标签的比力值;根据顶煤在放煤过程中的运移特点,提出了基于阈值的时间测量算法及基于长短期记忆(LSTM)的时间测量算法。基于阈值的时间测量算法通过引入静态阈值、最大阈值实现运动阶段的时间识别;基于LSTM的时间测量算法通过识别时域下比力值矢量和的动态变化,寻找突变点,实现运动阶段的时间识别。通过标签的自由落体实验完成了2种时间测量算法的性能测试,其中时间测量方差分别为0.000 6、0.000 2,时间测量误差分别为13.07%、5.22%,满足现场顶煤运移时间测量需求,基于LSTM的时间测量算法在顶煤运移时间测量具有明显的应用优势。

     

    Abstract: The multi-round sequential memory coal drawing technology can improve the recovery rate of top coal and gangue content in the fully mechanized working face. But it needs to accurately measure and control the time of each round of coal drawing in field application. In the practical application of the automatic coal drawing technology based on the top coal migration tracker, the top coal movement tracker is only used as a mark point and is arranged in the top coal. The top coal movement tracker can not obtain more top coal movement information. In view of the above problems, based on the top coal movement tracker, a top coal migration time measurement system based on accelerometer is designed. The system includes three parts: tag, collector and central computer. The label is placed inside the top coal, and moves along with the top coal in the coal drawing process. Through the built-in accelerometer, the specific force data is collected in real-time. The time measurement algorithm is called to realize the monitoring of top coal migration. Then the different coal drawing stages are determined. The top coal migration time information of different stages is calculated. When the tag is released from the coal chute, it collides with the scraper conveyor belt, and sends the top coal migration time information outward to the collector through the RF signal. The information is further transmitted to the central computer through the field bus to guide the fully mechanized working face to realize multi-round of sequential coal drawing on site. The hardware and software design of the time measurement label of top coal migration is introduced in detail. The functions of real-time acquisition of specific force value, wireless signal transmission and data storage are realized. A calibration platform with 3D turntable as the core and Gauss-Newton method as the calibration algorithm is built. The calibration of the accelerometer is completed. The calibrated accelerometer can accurately collect the specific force data of the top coal migration time measurement label. According to the migration characteristics of top coal in the process of coal drawing, the time measurement algorithm based on threshold and the time measurement algorithm based on long-term and short-term memory (LSTM) are proposed. The time measurement algorithm based on threshold realizes the time identification of motion stage by introducing static threshold and maximum threshold. The time measurement algorithm based on LSTM identifies the dynamic changes of the specific force vector sum in the time domain, finds the mutation point, and realizes the time identification of the motion stage. The performance test of the two time measurement algorithms is completed through the tag free falling experiment. The time measurement variance is 0.000 6 and 0.000 2 respectively. The time measurement error is 13.07% and 5.22% respectively. The results meet the on-site top coal migration time measurement requirements. And the time measurement algorithm based on LSTM has obvious application advantages in top coal migration time measurement.

     

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