2019 Vol. 45, No. 10

Display Method:
Smart mine with 5G and WiFi6
SUN Jiping, CHEN Huisheng
2019, 45(10): 1-4. doi: 10.13272/j.issn.1671-251x.17517
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Abstract:
Broadband wireless communication is foundation and key of smart mine construction. Special requirements for mine broadband wireless communication were proposed. Wireless signal is required to cover roadway more than 10 kilometers coal mine underground. Wireless transmission must be intrinsically safe. Wireless working frequency band should not be too high. Wireless transmission should have certain diffraction ability. Anti-interference ability is strong. Mobility requirements are not high. Mine-used 5G and WiFi6 were researched. Both 5G and WiFi6 can be used for broadband wireless communication in smart mine. Mine-used 5G has advantages of high transmission rate, small transmission delay and high call quality, but the system is complex and cost is high.Mine-used WiFi6 has advantages of high transmission rate, simple system and low cost, but transmission delay is large and call quality is poor.
Off-line measurement while drilling system for mine-used slewing drilling rig
ZHANG Wenjie, LIU Zongwei, SONG Jiancheng
2019, 45(10): 5-10. doi: 10.13272/j.issn.1671-251x.2019020032
Abstract:
For inability to directly measure attitude data of drilling tool at hole bottom and draw drilling hole trajectory during drilling process of mine-used slewing drilling rig, an off-line measurement while drilling system for mine-used slewing drilling rig was developed based on measurement while drilling principle and off-line data synchronization method. The system is composed of probe tube, synchronizer and host computer software. Probe tube measures gravitational field and geomagnetic field separately through triaxial accelerometer and triaxial magnetometer, so as to acquire drilling rod attitude. Synchronizer acquires numbers of drilling hole and drilling rod through press keys, and selects valid measuring points according to drilling rod attitude data. Host computer software draws 2D or 3D trajectory through measuring point recursion algorithm. The functional test results show that mold height of total geomagnetic field vectors measured by the system is close to real value of 50-60 μT, mold height of total gravitational field vectors is close to 1g, and the maximum dip-angle error is 1° and the maximum azimuth-angle error is 5° after correction by sensor correction algorithm. The underground test results show that trajectory of read-made drilling hole drawn by the system is basically the same as actual trajectory, but hole-mouth trajectory of drilling role is easily affected by magnetic interference of drilling rig to generate error, which leads bigger error of the whole drilling hole trajectory, so drilling rig should be 3 m away from hole-mouth at least.
Simulation analysis of roof beam position and attitude control of hydraulic support
REN Huaiwei, LI Shuaishuai, LI Xie, FU Zhuang
2019, 45(10): 11-16. doi: 10.13272/j.issn.1671-251x.17470
Abstract:
For rapidity and strong anti-interference requirements of self-adaptive control of hydraulic support controller under stable support state, a kinematics model of hydraulic support and a transfer function of hydraulic system in valve-controlled hydraulic cylinder were built taking ZY10800/28/63 roof-standing and shielding hydraulic support as a research object, and a RBF neural network controller including speed compensation was designed. Based on the controller, a roof beam position and attitude control system of hydraulic support was proposed, which ensured stability of roof beam height and attitude angle of hydraulic support under supporting condition through controlling length of column cylinder and equilibrium jack. A simulation model of the system was built in Matlab/Simulink and experiments were taken out. The experimental results show that the RBF neural network controller has short response time to step signal and no over-shoot. When impact force is loaded on roof beam, the RBF neural network controller has faster response speed, smaller over-shoot and stronger anti-interference performance than PID controller and sliding mode controller, which can keep roof beam position and attitude in target value with good stability.
Research on opposition-based enhanced fireworks algorithm optimization for mine ventilation network
WU Xinzhong, HU Jianhao, WEI Lianjiang, QIAN Xiaoyu, REN Zihui, ZHANG Zhichao
2019, 45(10): 17-22. doi: 10.13272/j.issn.1671-251x.17438
Abstract:
A non-linear unrestraint optimization model of mine ventilation network was established which took the minimum total energy consumption of mine ventilation network as optimization objective. In order to improve optimization ability and convergence speed of the model, an opposition-based enhanced fireworks algorithm(OBEFWA) was proposed. Firstly, population initialization strategy based on opposition-based learning and uniform randomization is adopted, and uniform randomization population generated by the strategy is competed with opposition-based population, so that the optimal initial population is selected as starting point of subsequent search. Secondly, fireworks explosion radius is finely controlled, so that explosion radius of fireworks populations of different generations shows non-linear decline, and that of the same population generation is coordinated and distriblted according to their own fitness values. The minimum dynamic threshold is set to decrease waste of search resources. Finally, selection strategy of elite opposition-based learning is adopted to strengthen search for neighborhood of elite fireworks, so as to improve global exploration ability of the algorithm. The experimental results show that total energy consumption of mine ventilation network optimized by OBEFWA decreases about 23.2% which meets adjustment constraints and wind demand of actual ventilation network, and OBEFWA has better optimization effect than particle swarm optimization algorithm and enhanced fireworks algorithm.
Research status and prospect of intelligentization technology of roadheader
LIU Songyong, ZHANG Deyi
2019, 45(10): 23-28. doi: 10.13272/j.issn.1671-251x.2019030031
Abstract:
The goal of roadheader intelligentization is to realize automatic accurate forming of roadway section by combining intelligent perception technology and adaptive operation, the key technology framework of roadheader intelligentization was explained from two aspects of intelligent perception and adaptive operation. Intelligent perception includes pose perception, shape perception and state perception, and adaptive operation includes adaptive rectification, adaptive cutting and adaptive diagnosis. Research status of technologies were summarized such as pose detection and rectification of roadheader, automatic forming of roadway section and adaptive cutting, and safe operation guarantee of roadheader. Inertial navigation/UWB combined positioning technology has strong applicability in underground confined space. Pitch pose rectification and directional walking of roadheader have been realized, but there are still problems such as large control error and poor accuracy of rectification control. The cutting method of avoiding large-area coal gangue belt provides a new idea for adaptive cutting, but position determination of coal gangue belt and application effect of the method in practice need further study. Common fault diagnosis method has certain applicability in the case that fault object is determined and fault cause is clear, however, due to the complexity and variety of the faults of roadheader, and the faults interact with each other, it is difficult to perform accurate and effective fault diagnosis. Intelligent technology breakthrough direction of roadheader is pointed out: research on navigation and positioning method with high detection precision, less interference and excellent applicability, realizing of dynamic compensation of pose deviation of roadheader, matching model of coal rock properties and the best cutting parameters, and state monitoring of roadheader.
Discussion on disaster environment detection technology of coal mine rescue robot
ZHENG Xuezhao, YAN Xing, CUI Jiaming, GUO Jun
2019, 45(10): 29-32. doi: 10.13272/j.issn.1671-251x.17477
Abstract:
Based on analysis of principle and characteristics of traditional water inrush source, fire and gas concentration detection technologies of coal mine rescue robot, water inrush source detection method of coal mine rescue robot based on wireless ad-hoc network, fire detection method of coal mine rescue robot based on big data and gas concentration detection method of coal mine rescue robot based on multi-source information fusion were proposed, which could effectively improve accuracy of water inrush water, fire and gas concentration detection of coal mine rescue robot. It was pointed out that disaster environment detection technology of coal mine rescue robot would deeply integrate modern information technologies such as cloud computing, artificial intelligence and Internet of things, so as to comprehensively improve reliability of disaster environment detection results of coal mine rescue robot.
Field measurement of the influence of coal face mining on adjacent main roadway deformatio
ZHANG Shaohua
2019, 45(10): 33-37. doi: 10.13272/j.issn.1671-251x.2019050025
Abstract:
At present, theory analysis and simulation analysis of surrounding rock control and deformation of main roadway often simplify some special conditions in the field, such as fault structure, which leads to large differences between simulation results and actual results. In view of the above problem,field measurement method is used to analyze deformation law of adjacent roadway after the coal face is mined, and influence of coal face mining on adjacent roadway is studied taking coal face of a mine as engineering background. Through analysis of roadway deformation data got by 14 measurements over a period of 3 months, the conclusions are obtained: roadway deformation in the area affected by mining is the result of comprehensive influence of working face mining, mining fault activation and cross stress concentration;roadway deformation speed decreases as the horizontal distance between measuring point and coal surface increases gradually, indicating that the influence of mining on roadway decreases gradually; deformation velocity characteristics of left-right sides of the roadway at different measuring points are similar to those of the roof-floor, and the deformation of roof-floor of the roadway is obviously larger than that of the left-right sides, indicating that the roadway is mainly affected by horizontal stress; during subsequent advance process of coal face, deformation monitoring of surrounding rock of the roadway should be strengthened when advancing to vicinity of fault intersection line.
Research on influence of the maximum principal stress direction on stability of roadway surrounding rock
LI Guiming, ZHOU Chao, WANG Xiaodong
2019, 45(10): 38-42. doi: 10.13272/j.issn.1671-251x.2019040058
Abstract:
In order to research influence of the maximum principal stress direction on stability of roadway surrounding rock, taking rectangular haulage roadway of 1101 working face in a mine in Guizhou as engineering background, deformation of roadway surrounding rock was researched when the maximum principal stress was horizontal or vertical stress by use of FLAC3D numerical simulation software. The research results show that when the maximum principal stress is horizontal stress, roof is greatly affected and prone to serious shear failure, and roof displacement is larger than that of two sides, so roof support should be strengthened. When the maximum principal stress is vertical stress, two sides are greatly affected and are prone to shear failure, and displacements of roof and two sides increase obviously with the increase of vertical stress, so two sides support should be strengthened. Based on numerical simulation results and the situation that horizontal stress is greater than vertical stress of the working face, the horizontal stress is approximately regarded as the maximum principal stress, and a supporting scheme was proposed which focused on roof support. The field monitoring results show that displacements of roadway roof and two sides are small after applying the support scheme, which verifies that the support scheme can maintain stability of roadway surrounding rock well.
Research on deformation characteristics of mining overburden rock on deep "three-sided" island working face
REN Mengli, CAI Feng, MEI Shengkai
2019, 45(10): 43-48. doi: 10.13272/j.issn.1671-251x.2019040001
Abstract:
In order to study deformation and failure characteristics of mining overburden rock on the deep "three-sided" island working face with old goaf on the left, right and upper sides, taking 120502 working face of a coal mine as research object, the stress of overburden rock, displacement and deformation characteristics in plastic zone in the mining process were systematically and numerically studied using FLAC3D simulation software. The results show that in the stoping process, the "three-sided" island working face with the old goaf on the left, right and upper sides is mainly disturbed by the upper old goaf, and stress concentration of left coal pillar in the prone direction is higher, the vertical stress in front of working face on strike direction decreases first and then increases continuously, and the stress concentration factor increases continuously. The direction of vertical displacement changes from downward to upward, and the downward vertical displacement peak increases continuously, but the upward vertical displacement peak remains stable. The damage range of plastic zone appears "saddle shape", and gradually expands to be connected with the plastic zone of the adjacent three old goafs, and the rock mass above the roof is in the tension-compression stress zone, and the cracks in the surrounding rock of the goaf are more fully developed. The gas near the old goaf and the pressure-removing coal body flows to the goaf in the mining layer, so the gas drainage work in the goaf of the working face should be emphasized.
Research on path smoothing algorithm of coal mine rescue robot
TAO Dejun, JIANG Yuanyuan, LIU Yanbin, XIN Yuanfang, LUO Jun
2019, 45(10): 49-54. doi: 10.13272/j.issn.1671-251x.2019050069
Abstract:
In view of problems that path planning of the coal mine rescue robot planned by A* algorithm has many path turning points and the path is not smooth enough, a path smoothing algorithm of coal mine rescue robot based on improved A* algorithm was proposed. Firstly, the Douglas-Peucker (D-P) algorithm is used to process the whole path generated by A* algorithm, and eliminate redundant nodes in the path, and extracts several path nodes as key nodes, which solves the problem that there are many redundant nodes and a large number of path turning points of the A* algorithm. Then, the whole path based on the key nodes is fitted by cubic path function, and a smooth path is obtained, which can effectively shorten the path length. The simulation results show that the algorithm has strong universality, although the planning time is slightly increased compared with the A* algorithm, but the planned path turns are few, the path length is short, and the path quality is relatively better than that of the genetic smoothing algorithm.
Conveyor belt tear detection method based on lion group optimization two-dimensional Otsu algorithm
GAN Fubao, HUANG Yourui, HAN Tao, XU Shanyong
2019, 45(10): 55-60. doi: 10.13272/j.issn.1671-251x.2019040015
Abstract:
The conveyor belt tear detection methods based on traditional two-dimensional Otsu segmentation algorithm adopts threshold selection method of exhaustive search. The image segmentation has a long time and poor real-time performance, which cannot meet requirements of tear detection accuracy and speed at the same time. For the above problems, a conveyor belt tear detection method based on lion group optimization two-dimensional Otsu was proposed. Firstly, the conveyor belt image is collected by the conveyor belt tear detection device, median filtering and histogram equalization were used to denoise and enhance the collected image to highlight the torn part. Then, the close to actual segmentation threshold of preprocessed image is obtained by lion group optimization two-dimensional Otsu algorithm, and the conveyor image is segmented by this threshold. Finally, the tear diagnosis is performed by calculating the number of black pixels in the segmented image. The simulation results show that the optimization ability of proposed method is more powerful than the traditional two-dimensional Otsu algorithm, and segmentation effect of conveyor belt is better, the cracks can be accurately segmented from the conveyor belt image. The correct rate of tear recognition of the method is 98.2%, improves the efficiency and shortens the running time, which can meet the accuracy and real-time requirements of the conveyor belt tear detection.
Sensorless control for permanent magnet synchronous motor of scraper conveyor
HU Wenbin, WANG Yujuan, ZHANG Chuanjin
2019, 45(10): 61-67. doi: 10.13272/j.issn.1671-251x.2019030018
Abstract:
Traditional rotor flux observers cannot accurately estimate rotor flux due to influence of DC disturbance and harmonic disturbance, and then sensorless control method of permanent magnet synchronous motor(PMSM) based on rotor flux cannot accurately estimate rotor position. In order to solve the above problem, a sensorless control strategy for PMSM of scraper conveyor based on third-order generalized integral flux observer(TOGIFO) was proposed. By introducing the TOGIFO, high-order harmonic component can be effectively suppressed, and DC component in rotor flux can be completely eliminated in steady state without amplitude attenuation and phase delay of fundamental wave, so as to accurately estimate rotor flux and improve accuracy of rotor position estimation. The simulation results verify correctness and effectiveness of the control strategy.
Prediction of coal and gas outburst intensity based on LLE-FOA-BP model
LONG Nengzeng, YUAN Mei, AO Xuanjun, LI Xinling, ZHANG Ping
2019, 45(10): 68-73. doi: 10.13272/j.issn.1671-251x.2019010054
Abstract:
In view of problems of low prediction accuracy, poor stability and slow training of current coal and gas outburst intensity prediction, a prediction method of coal and gas outburst intensity based on LLE-FOA-BP model was proposed. Essential characteristics of raw data of coal and gas outburst influencing factors are extracted taking use of the advantage of nonlinear data feature extraction of LLE algorithm, effective reconstruction factors are formed, and redundant information and noise between data are reduced. The weight and threshold of BP neural network are optimized by using FOA algorithm's strong global optimization ability to avoid falling into local minima and improve parameter optimization efficiency. Effective reconstruction factors are input into the optimized BP neural network for training, so as to realize quick and accurate prediction of coal and gas outburst intensity.The test results show that the average relative error of LLE-FOA-BP model is 8.06%, variance of relative error is 3.69, and training accuracy of 10-8 is achieved after 24 iterations, which verifies the model can improve robustness and learning efficiency while ensuring prediction accuracy.
Pressure relief mechanism and experiment of directional hydraulic fracturing in retaining roadway
LI Wujun, FU Yukai, WANG Tao, ZHANG Zhantao
2019, 45(10): 74-79. doi: 10.13272/j.issn.1671-251x.2019030008
Abstract:
Stress of upper coal pillar is the force source of strong deformation of retaining roadway. For surrounding rock control of retaining roadway with serious deformation, traditional blasting pressure relief technology has some problems such as high safety risk, environment pollution and serious surrounding rock damage. Aiming at the above problems, pressure relief mechanism of directional hydraulic fracturing in retaining roadway was proposed, that is, through expansion of hydraulic fracture, weak structural surface is generated in roof rock, overall strength of the roof rock is reduced, and the weakened hard roof is timely broken and caved under action of mining stress, so as to reduce stress level of retaining roadway. Taking 4312 fully mechanized coal mining face of Changping Coal Mine of Shanxi Jincheng Anthracite Mining Group Co., Ltd. as test site, boreholes scheme and boreholes layout parameters of directional hydraulic fracturing were determined. The fracturing results show that transverse grooving depth is 5 mm and grooving effect is good. During fracturing step by step, pressure required for fracture expansion increases with increase of distance between fracturing site and borehole. Surface displacement and coal pillar stress of fractured and non-fractured sections of retaining roadway were monitored. The monitoring results show that deformation of retaining roadway is mainly caused by two side walls deformation, and the average displacements of two side walls and roof and floor of the fractured section are about 40.79% and 69.80% lower than those of the non-fractured section. Stress of coal pillar in the non-fractured section appears peak point when approaching working face, while stress of coal pillar in the fractured section appears peak point at about 200 m away from back of cut hole of working face, which indicates that directional hydraulic fracturing transfers stress peak position of upper coal pillar.
A fault diagnosis method for coal mine machinery bearing
XU Qingqing, ZHAO Haifang, LI Shouju
2019, 45(10): 80-86. doi: 10.13272/j.issn.1671-251x.2019020005
Abstract:
Aiming at the problem that existing adaptive diagnosis methods of coal mine machinery bearing fault were susceptible to the interference of high frequency noise and intermittent noise, which led to the low accuracy of original signal decomposition and feature extraction, a fault diagnosis method for coal mine machinery bearing was proposed which was based on modified local mean decomposition(MLMD). The method adopts adjuvant noise decomposition method in self-adaptive decomposition part of local mean decomposition(LMD) method, namely adding Gaussian white noise to original signal firstly and then carrying out LMD, so as to restrain influence of high-frequency and intermittent noise on signal decomposition. In feature parameter extraction part, MLMD method does Hilbert transformation for product function components, then extracts feature parameters, so as to realize feature parameter extraction in whole value range. The simulation and test results show that MLMD method has good effect on decomposition and feature parameter extraction of bearing fault signal and high diagnosis accuracy of inner and outer ring fault of bearing.
High-pressure water mist automatic fire extinguishing system for flammable dust environment
MENG Xiangbao, WANG Junfeng, ZHANG Yansong, LIU Bo
2019, 45(10): 86-90. doi: 10.13272/j.issn.1671-251x.2019010059
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Abstract:
In view of problems that dry powder fire extinguishing agent will cause pollution, difficult cleaning and equipment damage, a high-pressure water mist automatic fire extinguishing system for flammable dust environment was designed. High-pressure energy storage system generates high-pressure water immediately and rapidly forms high-pressure water mist after flame sensor detects flame signal of flammable dust combustion, and then water supply system is quickly pressurized to working pressure, replaces high-pressure energy storage system to provide high-pressure water and continue to generate high-pressure water mist. The test results show that the high-pressure water mist automatic fire extinguishing system for flammable dust environment has fast response speed, average response time of flame sensor and controller is 4 ms and 12 ms respectively; high-pressure water mist generation is fast and average generation time is 96 ms, the longest generation time is 100 ms; the fire extinguishing is effective and timely, after the high-pressure water mist acts on combustion flame for 1 s, the combustion flame is basically extinguished, and the propagation and diffusion of combustion flame stops when propagates to about 0.2 m from the center ignition position. It is verified that the system can effectively avoid spread of flammable dust combustion flame and prevent flammable dust fire accidents.
Analysis of energy consumption characteristics of bluetooth low energy module
ZHUO Minmin, ZHAO Lichang, LI Jiyun
2019, 45(10): 91-94. doi: 10.13272/j.issn.1671-251x.2019080056
Abstract:
Coal mine electrical equipments can realize bluetooth communication function of low power consumption by integrating bluetooth low energy module(BLE). However, in the process of integrated design, power protection circuit and battery capacity should be designed according to energy consumption characteristics of BLE module. For the problem, under different power supply voltage and radio frequency power, high-side current monitoring chip ZXCT1010 was adopted to analyze energy consumption characteristics of BLE module under different working states such as reset, initialization, broadcasting and connection. The results indicate that energy consumption of BLE module in radio frequency(RF) transceiving is high, and RF transceiving duration is short, while energy consumption of BLE module in RF static state is low, and RF static state duration is long. Energy consumption of BLE module is less affected by change of RF power, but is greatly affected by change of power supply voltage. The higher the power supply voltage is, the higher the working current and energy consumption of BLE module in each running state will be. Therefore, suitable power supply voltage should be provided and RF power should not be limited in integration application of BLE module.
Random error identification for MEMS gyro in coal mine underground
CONG Lin, WANG Xiaolong, YAN Bi
2019, 45(10): 95-98. doi: 10.13272/j.issn.1671-251x.2018090084
Abstract:
Aiming at problems of unrevealing potential error source, hardly separating specific random error and long data collection time of common random error identification methods, Allan variance analysis method was used to identify random error of MEMS gyro in coal mine underground. Principle of Allan variance analysis method was introduced. Allan variance analysis method was used to process measured data of MEMS gyro, Allan standard deviation curves were given, and main random error coefficients of MEMS gyro were obtained by least square fitting. The experiment results verify validity of the Allan variance analysis method for random error identification of MEMS gyro.
Application research on roadway protection technology by hydraulic fracturing roof cutting pressure relief in underground coal mine
DONG Zhiyong
2019, 45(10): 99-103. doi: 10.13272/j.issn.1671-251x.17474
Abstract:
The gas concentration of No.8 coal seam in north 3 panel of Duerping Coal Mine is high, the direct roof and the basic roof are both hard limestone, and it is easy to form a large area of hanging roof in the upper corner after stoping on working face, which is not easy to collapse naturally in a short time, resulting in a high degree of stress concentration in the protective coal pillar of the adjacent working face. In the process of stoping of working face, floor gas drainage roadway arranged under the coal pillar is often affected by advance and lateral supporting pressure, which often results in large deformation and seriously affects ventilation and gas extraction of the roadway. Under influence of strong dynamic pressure, the floor gas drainage roadway shows intense pressure, which cannot satisfy the dual-use of one roadway. In view of the above problems, taking 68306 working face as research object, application research on roadway protection (floor gas drainage roadway) technology by hydraulic fracturing roof cutting pressure relief was carried out. The roadway protection technology by hydraulic fracturing roof cutting pressure relief was adopted on roof near the coal pillar side in air return way to cut off the connection between the roadway and the basic roof above the coal pillar, and minimize the length of side cantilever beam, weaken or transfer high stress of overlying coal pillar, reduce the load of coal pillar,so as to make 68306 floor gas drainage roadway be in a low stress area, fundamentally change the stress state of roadway surrounding rock,which achieves the effect of pressure relief and protect the roadway. The test results show that the deformation of surrounding rock of floor gas drainage roadway is obviously reduced after implementation of roadway protection technology by hydraulic fracturing roof cutting pressure relief, the deformation of the two sides and the roof and floor are controlled within 12% and 20% respectively. After using hydraulic fracturing roof cutting in air return way, the area of hanging roof in the upper corner of the working face is effectively controlled, and the gas accumulation in the upper corner is avoided.
Design of online fault diagnosis and early warning system for coal mine rotating machinery
YANG Yiqing, MA Hongwei, FAN Hongwei, ZHANG Xuhui, ZHANG Chao, HAN Lei
2019, 45(10): 104-108. doi: 10.13272/j.issn.1671-251x.2019010092
Abstract:
In view of problems that existing coal mine machinery online monitoring and diagnosis technology did not realize online extraction of fault characteristics and automatic identification of fault types, an online fault diagnosis and early warning system for coal mine rotating machinery based on LabVIEW was designed. The system analyzes vibration signal by means of spectrum analysis, power spectrum analysis, envelope spectrum analysis and cepstrum analysis, and obtains characteristic parameters of each component in running process of the rotating machine, and compares it with characteristic parameters in fault type database to realize fault diagnosis. Two kinds of fault diagnosis modes are designed including fine diagnosis and rough diagnosis, the two modes are associated by interlocking. If structural parameters of the main components of rotating machine are known, the fine diagnosis mode can be selected,otherwise, the rough diagnosis mode can be selected. Performance of the system is verified by simulating rotor unbalance fault of rotating machine, and the results show that the system can accurately identify faults and issue prompts with simple operation and high reliability.