2020 Vol. 46, No. 12

Display Method:
Multi-level safety situation awareness system for mines
LI Jingzhao, MENG Yifan, WANG Jiwei
2020, 46(12): 1-6. doi: 10.13272/j.issn.1671-251x.17672
<Abstract>(107) <HTML> (24) <PDF>(19)
Abstract:
In the process of intelligent mine construction, it is essential to analyze massive mine monitoring data from a global perspective so as to observe the mine safety situation comprehensively. To address this issue, a multi-level safety situation awareness system for mines is proposed. The system analyzes the monitoring data of each subsystem within the mine area by deploying a local safety situation awareness model in the fog computing facility to observe the local safety situation of the mine. The local safety situation is gathered to the cloud computing facility through the high-speed communication network of the mine. The global safety situation is further achieved by the global safety situation awareness model deployed in the cloud computing facility. The local and global safety situation awareness model processes the correlation between the data by using the encoder and decoder based on the gated recurrent unit. The Attention mechanism is applied in the model so as to filter the key data and improve the model’s computing speed. Meanwhile, in order to make the model run in the best state, the particle swarm algorithm is used to find the optimal hyperparameters of the model. The simulation results show that the safety situation awareness model has high accuracy.
Man-vehicle linkage control system in coal mines
SUN Jiechen, LI Jingzhao, WANG Jiwei, XU Zhi
2020, 46(12): 7-12. doi: 10.13272/j.issn.1671-251x.17679
<Abstract>(117) <HTML> (18) <PDF>(18)
Abstract:
In order to ensure the safety of people in the roadway during the movement of unmanned transportation vehicles in coal mines, a man-vehicle linkage control system in coal mines is proposed. A deep separable convolutional network is used to replace the DarkNet-53 feature extraction network of the YOLOv3 target detection model to improve the real-time performance of target detection. Based on the idea of upsampling and feature pyramid network, the feature map scale is expanded so as to ensure the accuracy of target detection. The improved YOLOv3 target detection model is used to detect the position of man in coal mines as the vehicle is moving. Based on the distance between the man and the vehicle, the PID control optimized by the genetic algorithm is used to achieve speed and precise adjustment of the vehicle. The experimental results show that the system can quickly detect the position of target man and control the vehicle speed according to the distance between the man and the vehicle with high reliability.
Lightweight CNN and its application in coal mine intelligent video surveillance
XU Zhi, LI Jingzhao, ZHANG Chuanjiang, YAO Lei, WANG Jiwei
2020, 46(12): 13-19. doi: 10.13272/j.issn.1671-251x.17674
<Abstract>(114) <HTML> (13) <PDF>(20)
Abstract:
The massive amount of surveillance video in coal mines is transmitted to the cloud computing center for centralized processing through Ethernet. This method has problems such as high latency, high cost and high network bandwidth occupation. To address the above problems, a lightweight convolutional neural network (CNN) model is constructed with depthwise separable convolution as the core. Moreover, the lightweight CNN model is optimized by introducing the residual structure to improve the image feature extraction ability. The low contrast of surveillance video images caused by the complex lighting environment in coal mines affects the recognition accuracy of the model. Hence, the contrast limited adaptive histogram equalization (CLAHE) algorithm is used to improve the brightness and contrast of images so as to improve the recognition effect of the model. The lightweight CNN model is compressed by STM32Cube AI and deployed on the embedded platform. A video surveillance terminal based on the lightweight CNN model is designed to perform real-time and intelligent processing of coal mine surveillance video locally to achieve real-time identification and alarming of coal mine violations. Experimental results show that by introducing the residual structure to optimize the lightweight CNN model and using the CLAHE algorithm for image enhancement, the model can achieve an accuracy of more than 95% for recognizing various violations in coal mines and improve real-time response to violations.
Intelligent loading system for bulk materials based on FWA-RFN
LIU Zechao, LI Jingzhao, OUYANG Qichun, WANG Jining
2020, 46(12): 20-24. doi: 10.13272/j.issn.1671-251x.17673
<Abstract>(58) <HTML> (15) <PDF>(14)
Abstract:
In order to solve the problems of serious unbalanced loading and large errors during the loading of bulk materials in coal mines, an intelligent loading system for bulk materials based on the fireworks algorithm (FWA) optimized recursive fuzzy neural network (RFNN) is proposed. By comparing the measured value and the set value of train carriage speed, the deviation is obtained as the input of RFNN controller. The deviation is processed by RFNN controller for fuzzification, dynamic memory adjustment and defuzzification. FWA is used to optimize RFNN weight so that RFNN controller can self-adaptively output the corrected control parameters. The traction motor frequency is obtained by the bulk material loading metering model, the material quality, material height and distance traveled during carriages loading collected by each sensor and the control parameters output from RFNN controller. Furthermore, the traction motor speed is changed so as to adjust the train carriage speed and realize the unbalanced loading of bulk materials. It has been proved that RFNN controller optimized by FWA can quickly adjust the carriages speed and keep the speed stable so as to meet the requirements of distributed and balanced loading of multiple carriages and improve the loading accuracy at the same time.
Research on intelligent management system of large coal group
LIU Yinzhi, ZHAO Tingzhao, MAO Shanjun, YUAN Shengfu, LIU Hui, WANG Zhijie
2020, 46(12): 25-30. doi: 10.13272/j.issn.1671-251x.17691
<Abstract>(72) <HTML> (15) <PDF>(21)
Abstract:
Intelligent management is an integral part of intelligent mine construction. The main problems of information management in large coal groups are analyzed, including the weak processing capability of management platform for heterogeneous data, the lack of dynamic integration of spatial characteristics information in business systems, the inability to conduct intelligent analysis of 'human, machine, environment and management', and the lack of collaborative early warning and linkage functions based on work flow and big data analysis. To address the above problems, the overall design scheme and architecture of intelligent management system of large coal groups are proposed. The key technologies such as heterogeneous data processing, model database and knowledge database construction, big data analysis and control collaboration adopted during the system construction are described. The system has been applied in the headquarters, secondary companies and subordinate mines of Henan Energy & Chemical Group Co., Ltd. and has improved the work efficiency of management positions by about 20%, reduced the work intensity of dispatching statistics and monitoring positions by about 35%. The system has achieved the system construction goals of platform standardization, space-time integration, intelligent analysis and management coordination, and improved the intelligent management level and decision-making efficiency of large coal groups.
Automatic operation and manual intervention analysis system for intelligent fully mechanized caving face
HAN Xiuqi, YANG Xiuyu, SUN Feng, ZHAO Dongsheng, HUO Dong
2020, 46(12): 31-37.. doi: 10.13272/j.issn.1671-251x.2020020047
<Abstract>(80) <HTML> (10) <PDF>(16)
Abstract:
In the context of intelligent fully mechanized caving and mining, it is important to consider not only the cutting by the shearer, but also the coal caving at the back of the support and top coal recovery. Compared with intelligent fully mechanized mining face, the characteristic features of intelligent fully mechanized caving face are having more equipment, more complicated working conditions, more possibilities of abnormalities in the production process and more manual remote interventions. In order to ensure the smooth operation of intelligent fully mechanized caving and mining, automatic operation and manual intervention analysis system for intelligent fully mechanized caving face is designed. The definitions of key indicators are defined, such as the automation rate of intelligent fully mechanized caving face and the operation rate of the caving face control system,the shifting rate of automatic following machine of the hydraulic support, shearer memory cutting rate and automatic roof coal caving rate. By collecting the operation information of the main equipment in fully mechanized caving face and the coal mining information, the operation status of each equipment is reviewed and the statistical analysis of automation rate of fully mechanized caving face is obtained. Based on the threshold knowledge information and equipment work-flow of the automatic operation status of fully mechanized caving face, threshold knowledge database of the automatic operation state change of intelligent fully mechanized caving face is established. The database is used to identify the status of production equipment before manual intervention and estimate whether it is suitable to stop automatic operation of production equipment. Based on the in-depth analysis of expert knowledge, a rule database is established. When implementing manual intervention, the database automatically estimates whether the conditions for removing automation are met based on the rules in rule database, and analyzes the reasons for manual intervention. The results show that the system is able to evaluate the automation rate of intelligent fully mechanized caving face, analyze the reasons for manual intervention, and provide a basis for optimizing the control logic of production system.
On-line relay protection setting system for mine power grid considering multi-scenario operation mode
YU Qun, LIU Jiayu
2020, 46(12): 38-47. doi: 10.13272/j.issn.1671-251x.2020100002
<Abstract>(58) <HTML> (12) <PDF>(11)
Abstract:
Although the existing research on mine power grid relay protection setting has studied the setting methods of mine power grid relay protection under different operation modes, but it has not studied the setting method that applied in the automation system of mine power supply and dispatching. Therefore, the setting value could not be calculated in real time as the operation mode of the mine power grid changes. The new setting value can not be given to the protection that does not meet the requirements. To address the above problems, on-line relay protection setting system for mine power grid considering multi-scenario operation mode is proposed by defining the combination of a certain type of circuit breaker status on the bus power side of the outgoing line of the protection position as a mine power supply system scenario. The system uses the scenario corresponding switch state matrix to calculate the scenario area matrix and scenario network branch impedance matrix of the mine power supply system. Then the system calculates the maximum and minimum system impedance of the scenario based on the scenario area matrix and scenario network branch impedance matrix. As the change of breaker switching state or the scenario is monitored, the real-time switching state of the breaker is automatically read. The scenario class with the state change switch is found through the scenario switch information matrix. A scenario class is selected according to the number of switches in the scenario class, and the setting value of protection corresponding to the scenario class is calculated. Based on the calculation result of the setting value, it is reviewed whether the protection performance meets the requirements.If not meeting the requirements, on-line setting calculation will be carried out. If meeting the requirements, then the calculation of the scenario class will be completed, and the next scenario class will be calculated until the all scenario classes being calculated.The application results show that by communicating with the mine power supply dispatching automation system, the protection range of the on-line relay protection setting system for mine power grid considering multi-scenario operation mode can adapt to the requirements of relay protection devices in various operation modes. Moreover, the method avoids the rejection and misoperation of relay protection devices caused by the setting value not meeting the requirements after the change of operation mode.
Discussion on key technologies of multi-rotor detection UAVs in mine dangerous area
ZHENG Xuezhao, TONG Xin, ZHANG Duo, GUO Jun, ZHANG Yanni
2020, 46(12): 48-56. doi: 10.13272/j.issn.1671-251x.17653
Abstract:
The research status of the key technologies of multi-rotor detection unmanned aerial vehicles(UAVs) in mine dangerous areas at home and abroad is reviewed from three aspects: autonomous positioning and navigation technology, autonomous obstacle avoidance technology and multi-sensor information fusion technology. Autonomous positioning and navigation technology enables robots to move autonomously in unknown environments without human intervention. Combined navigation technology, 3D environment map building technology, deeply optimized trajectory planning algorithms and simultaneous positioning and map building technology based on semantic and deep learning are suitable for mine conditions with complex and unstable mine environmental conditions where disaster information evolving over time.The obstacle avoidance method based on multi-sensor information fusion can ensure that the multi-rotor detection UAV can perceive obstacle information to the maximum extent under different environmental conditions. The sensor fusion architecture based on autonomous positioning and obstacle avoidance technology need to adopt a distributed structure to make the mine multi-rotor detection UAV system have high reliability and fault tolerance.The problems of multi-rotor detection UVAs are analyzed from both software and hardware aspects. The problems include that the universality of the fusion model and algorithm cannot be guaranteed,the fusion system's fault tolerance or robustness needs to be improved, the lack of processing hardware to adapt to a variety of complex fusion algorithms, and the low degree of integration, high power consumption and large size of multi-sensor.The development trend of key technologies of multi-rotor detection UAVs in mine dangerous areas is prospected. ① Fusion algorithm optimization: it is crucial to maximize the optimization of fusion algorithm, improve system reliability and stability and ensure stable and efficient data processing. ② Application of artificial intelligence technology: improving the deep learning ability of multi-rotor detection UAVs and expanding the detection range of mine dangerous areas by applying intelligent technologies such as machine learning and adaptive technology. ③ Development of processing hardware that can adapt to multiple complex fusion algorithms: the conditions of mine dangerous area are extremely complex, and it is difficult to achieve simultaneous collection and processing of underground multi-source information without the processing hardware that can adapt to the deep fusion of multiple algorithms. Therefore, the information processing ability of multi-rotor detection UAVs can be improved by developing processing hardware with strong adaptability. ④ Development of convenient hardware fusion system: developing a fusion system based on the deep integration of multiple sensors could further enhance the detection capabilities of multi-rotor detection UAVs.
Research on shearer performance degradation evaluation and applicatio
ZHAI Wenrui, LI Xiangong, WANG Jiaqi, DING Weikai
2020, 46(12): 57-63. doi: 10.13272/j.issn.1671-251x.2020060014
Abstract:
Accurate identification of the wear and failure of shearer components can provide the necessary support for the prevention and early warning of shearer failures and related accidents, and shearer performance degradation evaluation is an effective way to identify the wear and failure of shearer. For the non-linearity of shearer performance degradation process, an artificial intelligence-based shearer performance degradation evaluation method is proposed. The working condition monitoring parameters and performance monitoring parameters of the shearer are achieved, and the working condition of the shearer is identified by applying the extreme learning machine method. The performance monitoring parameters are dimension reduced by using the principal component analysis method, and the benchmark Gaussian mixture model under each working condition is established. The relative entropy is used to measure the difference between the Gaussian mixture model and the benchmark Gaussian mixture model at a certain moment, so as to measure the performance degradation trend of each component of the shearer. It is proposed that the performance monitoring parameters can be obtained from geological conditions, environmental factors, vibration and load, shearer tilt, etc. The parameters can be obtained according to the availability of data and changes in practical applications. The principles of selecting shearer performance monitoring parameters are proposed, and the performance monitoring parameters can be chosen based on the classification of common electromechanical equipment monitoring parameters and the actual assembly condition of the shearer sensor. A case study is carried out by analyzing the performance of shearer cutting part, which is the part with the highest fault rate. The working conditions of the cutting part of the shearer are divided into four types: high-speed straight cutting, high-speed oblique cutting, low-speed straight cutting and low-speed oblique cutting. The traction speed is used as the working condition monitoring parameter, and the left cutting motor current is used as the performance monitoring parameter. The rationality of the parameters is verified by correlation analysis. The analysis results show that the performance degradation status of the shearer can be obtained by comparing Gaussian mixture model, and the performance degradation trend of the shearer cutting part at each monitoring point can be measured through the relative entropy.
Research and application of combined load-bearing shell support for deep soft rock roadway
DUAN Changrui, ZHENG Qun, YU Guofeng, AN Shikai, LI Zhibing
2020, 46(12): 64-69. doi: 10.13272/j.issn.1671-251x.2019080019
Abstract:
There are many influencing factors and complex conditions in deep soft rock roadway support. The theoretical research is still in the exploratory stage. Moreover, the method of relying on improving the strength of support materials and the use of grouting bolts can not fundamentally solve the problems and the cost is high. This paper analyzed the stress distribution of deep soft rock roadway surface surrounding rock. The deformation characteristic was that the stress transferred to deep mine and the stress of roadway surface surrounding rock reduced while the deformation increased. It was found that the crucial methods to solve the deep soft rock roadway support problems are to maximize the strength of supporting structure and to reduce the tangential stress around the supporting structure. This meant that the small inner supporting structure should be well designed and the intermediate stress reduction layer should be constructed. The inner supporting structure and the large outer structure of original rock were designed to form a deep soft rock roadway support system to enhance the self-supporting capacity of surrounding rock. According to the requirement of the small inner supporting structure, a full-section anchor shed grout joint support technology of load-bearing shell combined with active and passive support was proposed. On the basis of anchor (cable) support, steel supporting structure and filling structure behind walls formed inner supporting structure with certain thickness and high strength. Therefore, the structure reduced the contact between the roof, the coal wall and the air. At the same time, the filling grouting material spread and solidified in the deep soft rock cracks. The steel frame acted as a radial restraint after certain pressure-relief deformation of the surrounding rock, which could strengthen the surrounding rock load-bearing ring and ensure the stability of the surrounding rock. In the windstone gate restoration project of No.2 West Mining Area of Dingji Coal Mine, a full-section anchor shed grout joint support technology of high preload anchor cable + U-shaped steel shed + anchor shed grout injection was adopted. And the intermediate stress reduction layer was constructed by deep hole blasting method. The mine pressure observation results showed that the maximum value of the two sides of the roadway was 349 mm, the maximum value of the roof subsidence was 323 mm and the roadway deformation was effectively controlled.
Influence of primary side detuning parameters on three-coil magnetic resonance wireless power transmission system
QIAN Peicong, LU Yimi
2020, 46(12): 70-75. doi: 10.13272/j.issn.1671-251x.2020040087
<Abstract>(101) <HTML> (11) <PDF>(8)
Abstract:
Three-coil magnetic resonance wireless power transmission (MR-WPT) system with cross-coupling is in a detuned state on the primary side, resulting in a decrease in the transmission power of the system. However, the existing methods for studying the relationship between detuning parameters and transmitted power of MR-WPT systems have problems such as a large number of detuning parameter variables, complex relationships between parameters and large control algorithm calculations. To address the above problems, a three-coil series-connected MR-WPT system primary-side detuning parameter design method is proposed with a three-coil series-connected magnetic resonance detuning topology. This method simplifies the parameter calculation process by introducing a virtual coupling factor without complicated algorithms and designing additional hardware circuits. The influence of the primary-side detuning parameters on three-coil MR-WPT system is studied, and the relationships between different virtual coupling factors, detuning factors and system transmitted power in the three coil loops of the MR-WPT system are analyzed. ① The internal resistance ratio between transmitting coil and relay coil loops can illustrate whether there is frequency splitting in the system. ② When the virtual coupling factor value of transmitting coil and relay coil equals with the value of relay coil and receiving coil, the corresponding output power of the system is greater than the output power with unequaled values. The output power of the system is maximum when the virtual coupling factor value of transmitting coil and receiving coil is 1. ③ The detuning factor can measure the detuning degree of the primary side. The larger value means the greater detuning degree of the primary side and the smaller value means the smaller detuning degree of the primary side. ④ When the detuning factor value is fixed, the larger the quality factor is, the smaller is the difference between working frequency and resonance frequency as well as the detuning degree. When the detuning factor is fixed, the smaller the quality factor is, the larger is the difference between working frequency and resonance frequency as well as the detuning degree. When designing the detuning parameters of the primary side, it is suggested to choose larger quality factors to reduce the fluctuation of detuning frequency. The experimental results verify the correctness of the parameter design and analysis results.
Multi-decision tree prediction model for coal seam floor water inrush based on cost-sensitive theory
LI Yanmin, ZHOU Chenyang, LI Fenglian
2020, 46(12): 76-83. doi: 10.13272/j.issn.1671-251x.2020060071
<Abstract>(70) <HTML> (11) <PDF>(14)
Abstract:
When predicting coal seam floor water inrush, the situation is generally divided into two states: safe state and water inrush state. The state data has non-equilibrium characteristics. The existing coal seam floor water inrush prediction models are mainly suitable for balanced data. In the context of processing unbalanced data sets, the results often show "one-sided" phenomenon which means that the accuracy of safe state prediction is significantly higher than the accuracy of water inrush state, therefore the overall prediction performance is low. To address this problem, the multi-decision tree prediction model for coal seam floor water inrush based on cost-sensitive theory is established. In this model, each decision tree selects different water inrush factors as the root node of the single decision tree, and the node attribute selection criterion of single decision tree combines the cost-sensitive theory and Gini index, thus increasing the penalty for false prediction of water inrush data (minority of cases) and improving the prediction performance of water inrush. The rule set of single decision tree water inrush prediction model is obtained, and the rule set of the multi-decision tree water inrush prediction models are obtained by combining all the rules sets of single decision tree water inrush prediction models. The rule set of the multi-decision tree water inrush prediction models is used to obtain the prediction results of multiple water inrush data. Hence, the final prediction results are obtained based on the voting method and the minority obeying the majority principle. The experimental results show that as the penalty factors of the model increasing, the prediction result of the true positive rate presents a trend of first increasing and then decreasing. Compared with the single decision tree water inrush prediction model based on the classification regression tree (CART) algorithm, the true positive rate of the model can reach 93.06%, and the true negative class rate can reach 97.85%, and the accuracy rate is 96.25% with the data imbalance rate of 2 and the classification error penalty factor of 4. The performance is better than the performance of the water inrush prediction model based on the CART algorithm.When the data imbalance rate is increased to 6 and the penalty factor for classification error is set to 20, the positive class rate of both models reaches 100%. The negative class rate of this algorithm is 99.37% and the accuracy rate is 99.47%, which is still better than the performance of the CART-based water inrush prediction model. The experimental results validate the effectiveness of this model.
Cutting coal path planning of shearer up-drum based on double arc spline curve
CHAI Haoluo, XING Cu'en, HUA Tongxing
2020, 46(12): 84-89. doi: 10.13272/j.issn.1671-251x.2020060049
Abstract:
The life of the drum cutters is shortened and the coal output rate is reduced due to the problem that the shearer up-drum often cuts the roof rocks. It is therefore essential to plan the cutting path of the up-drum. However, the characteristic features of traditional methods are large errors, inability to adapt to changes in geological conditions and complicated algorithms. A method for cutting coal path planning of shearer up-drum based on double arc spline curve is proposed to solve the above problems. Firstly, the data of borehole, return airway, headentry and open-off cut from the working face is collected to build a three-dimensional geologic model of coal seam; Secondly, the model is simulated and cut to obtain a set of roof control points according to the coal wall spatial coordinate system, and a continuous control point coordinate system is established with two adjacent points as a group. The arc radius and center coordinates are calculated according to the basic structure of double arc, and the path between two adjacent control points, namely the up-drum cutting path, is obtained according to the arc parameters. A genetic algorithm is used to analyze the relationship between the roof curve and the cutting path so as to establish the rock fitness function model. A more reasonable and accurate cutting path is achieved by simulating and optimizing the cutting path through selection, crossover and mutation operations. Simulation results show that a smoother cutting path is obtained through genetic algorithm optimization. The error range between the up-drum cutting path and the roof is 0.183 9-0.349 3 m. The problem that the up-drum cutting the roof rocks has been improved, indicating that the optimized path effectively reduces the gangue amount and increases the recovery rate.
Improved gray wolf optimization algorithm for solving low-carbon transportation scheduling problem in open-pit mines
MEN Fei, JIANG Xi
2020, 46(12): 90-94. doi: 10.13272/j.issn.1671-251x.2020070049
Abstract:
In order to solve the problem of low-carbon transportation scheduling in open-pit mines, the mathematical model is established by taking the mining volume, crushing volume of crushing stations and the number of trucks as constraints and taking the minimum sum of carbon emission cost and transportation cost as the objective function. An improved gray wolf optimization algorithm is proposed for the problem that gray wolf optimization algorithm is easy to fall into local optimum when it is used to solve the low-carbon transportation scheduling problem of open-pit mines. The algorithm introduces migration operation in the gray wolf optimization algorithm and dynamically modifies the migration probability of the gray wolf optimization algorithm according to its fitness function value. It is beneficial to go beyond the local optimum and obtain the global optimum faster so as to effectively balance the global optimization ability and local optimization ability. Experimental results show that the algorithm has higher optimization accuracy and faster optimization speed. By applying this algorithm to optimize low-carbon transportation scheduling in open-pit mines, transportation efficiency has been improved and carbon emissions and transportation costs have been reduced.
Research on positioning algorithm of electric mine shovel based on UWB technology
GUO Anbin, SU Hongjun, YAN Xiaoheng
2020, 46(12): 95-100. doi: 10.13272/j.issn.1671-251x.2020070067
<Abstract>(100) <HTML> (14) <PDF>(14)
Abstract:
In the harsh working environment of mines, the traditional cable reeling method cannot guarantee the power supply of electric shovel for a long time, and there are hidden safety hazards in the process of power supply. A new cable reel car which follows the shovel is proposed to address the above problems. In order to realize the autonomous following of electric shovel by cable reel car and ensure the long time power supply of electric shovel in mining environment, the positioning algorithm of electric mine shovel based on ultra wide-band (UWB) technology is proposed and time difference of arrival (TDOA) algorithm is used to construct the positioning model of electric mine shovel. Based on the TDOA ranging algorithm, the distance from each base station to the target electric shovel position is measured and the difference is calculated. The distance difference information obtained is moving average filtered to suppress the noise generated in the ranging process and achieve smooth data. The tag position is calculated according to the distance difference after filtering correction. The target electric shovel position is tracked with the strong tracking extended Kalman filter (STFEKF) algorithm to further eliminate noise and improve the positioning accuracy of the target electric shovel during movement. The simulation results show that under the influence of different observation noises, the error of the moving filter + STFEKF positioning method is smaller than that of the traditional EKF algorithm. This method effectively solves the problem of positioning error increasing with the distance increasing or the sudden change of shovel movement. The positioning mean square deviation is reduced by more than 70% compared with the traditional EKF algorithm, and the positioning trajectory is closer to the real movement trajectory of the target with good performance of positioning tracking and noise suppression.
Remote firmware update method for multi-layer heterogeneous networks in coal mines
YUAN Fengpei
2020, 46(12): 101-105. doi: 10.13272/j.issn.1671-251x.2020050012
Abstract:
At present, remote peer-to-peer firmware updates have been implemented in the multi-layer heterogeneous network of coal mines, but the firmware of devices at all levels cannot be directly updated from the ground control host. The maintenance workload is relatively large when the sensors are distributed and the number is large, thus a remote firmware update method for multi-layer heterogeneous network of coal mines with unlimited levels and multiple links is proposed. The method is proposed that the host sends the firmware and its routing, and devices at all levels parse the routing, forward the firmware or update itself. The update process can display its progress information. The characteristic features of the firmware data in multilayer heterogeneous networks is transferring through multiple devices and links to reach the target device. This paper is proposing that the core of realizing remote firmware updates in multi-layer heterogeneous networks lies in routeing description. Moreover, this paper studies the method and process of realizing routing description by using JS object notation (JSON) from three aspects: device property description, network topology construction and firmware routeing description. The lower and upper computer software design method for implementing remote firmware updates of multi-layer heterogeneous networks in coal mines is introduced. A four-layer heterogeneous network experimental system containing Ethernet, RS485 bus and CAN bus is built, and the feasibility and stability of the JSON routing description based remote firmware update method for multi-layer heterogeneous networks in coal mines is verified by the statistics of the success rate and update time of each layer device firmware update.
Research on automatic picking of microseismic first arrival
GAO Yu, HU Binxin, ZHU Feng, ZHANG Hua, SONG Guangdong, GAO Guofang, PANG Jiangbo, ZHONG Guodong, QUAN Ni
2020, 46(12): 106-110. doi: 10.13272/j.issn.1671-251x.17564
<Abstract>(97) <HTML> (12) <PDF>(20)
Abstract:
Accurate picking of the first arrival of microseisms is the prerequisite for the estimation of source location. The traditional manual picking method is inefficient and time-consuming. The short time average long time average (STA/LTA) method, commonly used in automatic picking, has low picking accuracy for low signal-to-noise ratio signals. To address the above problems, a random forest-based automatic picking method of microseismic first arrival is proposed. Firstly, this study extracts the amplitude, energy and amplitude ratio of adjacent moments of microseismic data as features and mark each sample with feature categories. Secondly, a random forest model is constructed to identify microseismic first arrivals. Thirdly, the random forest model is used to calculate the probability of each test sample belonging to a certain category, and the first data sampling point with a probability of no less than 0.5 is defined as the microseismic first arrivals sampling point. In this experiment, microseismic monitoring data in deep boreholes of coal mine roadways is used. The results show that as the number of decision trees reaching 137 and the maximum depth reaching 6 in the random forest algorithm, the accuracy of the method for classifying microseismic data samples could reach 98.5%, and the average picking error for first arrivals of microseismic is 23.1 ms. Therefore, this method is better than the method of STA/LTA in terms of picking accuracy.
Design of wireless pressure sensor of hydraulic support based on LoRa technology
LI Qiwei
2020, 46(12): 111-115. doi: 10.13272/j.issn.1671-251x.2020040021
<Abstract>(105) <HTML> (14) <PDF>(25)
Abstract:
In coal mine roof pressure monitoring system, the issues of wireless ZigBee sensors are not being long-lasting as designed and requiring frequent battery replacement. Hence, a wireless pressure sensor of hydraulic support based on LoRa technology is designed to address these problems. The wireless pressure sensor embedded LoRa module is installed on the hydraulic support to collect the pressure values of the front pillar, the rear pillar and the forepole. The measured liquid medium is pressurized to the piezoresistive element of the sensor through the pressure hole. The deformation of the piezoresistive element under pressure produces resistance change which is linearly related to pressure. The micro-control unit of the sensor measures the voltage which applied to the resistance and converts the voltage to the actual pressure value. The sensor achieves wireless long-range, low-power and high-reliability transmission of the coal mine roof pressure monitoring signal by using three methods: the direct sequence spread spectrum technology with high spread spectrum improves the sensitivity of the receiving end, achieves high signal gain and increases the communication distance; the forward error correction coding technology improves the transmission reliability; the sensor enters sleep mode to reduce the power consumption after collecting the pressure value of the hydraulic support and sending the data successfully. The test results show that the average power consumption of the sensor is 1.18 mA·h for 1 h and the theoretical endurance of the 5,000 mA·h lithium battery is 141 days. The sensor performance meets the need of coal mining. Comparing with ZigBee technology, LoRa shows better performance for long-range transmission and higher reliability.
Underlying platform construction of intelligent open-pit mines
WANG Meng, MA Xiaoyan, GUO Chengbin
2020, 46(12): 116-119. doi: 10.13272/j.issn.1671-251x.2020050079
<Abstract>(107) <HTML> (17) <PDF>(20)
Abstract:
In this paper, it is pointed out that there are several main problems in the construction of intelligent open-pit mines in China at this stage, such as independent systems, mainly relying on manual control, passive implementation of disaster monitoring and lack of intelligent analysis. Moreover, this paper explores the connotation of intelligent open-pit mines and defines the intelligent open-pit mines as a large intelligent driven system consisting of Internet of everything and platform integration. The underlying platform of intelligent open-pit mines based on industrial Internet of things cloud operating system is proposed. Real-time data is obtained by advanced programmable remote utility server via Modbus/OPC/PPI/MPI and other industrial protocols. Off-line data can be entered manually according to the needs of field work. These data can be connected to the existing ERP or manufacturing execution system of open pit mining enterprises to realize the seamless connection of external data. Based on the industrial Internet of Things cloud operating system MixIOT as the platform, raster database, offline database, statistical database, report database, etc. are established according to different data sources to realize routing, exchange and storage of all kinds of data in open pit mines. At the same time, industrial data analysis service system is used to analyze the operation of open-pit mine production equipment. The three key technologies of the underlying platform of intelligent open-pit mines are data acquisition technology, data analysis service technology and application display technology.