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- Online First 2023, Volume 49, Issue 2 Cover Catalogue Previous Issue
Online First have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
2023, 49(2): 1-5.
doi: 10.13272/j.issn.1671-251x.18072
Abstract: The powerful radio waves can ignite explosive gases. Therefore, it is necessary to reasonably set the radio wave explosion-proof safety power and energy threshold emitted by the radio transmitter to limit the radio wave power and energy emitted by the radio transmitter. The radio wave explosion-proof safety power and energy thresholds specified in European Standard CLC/TR 50427:2004 Assessment of inadvertent ignition of flammable atmospheres by radio-frequency radiation-Guide are the ignition power and energy threshold. The national standard GB/T 3836.1-2021 Explosive atmospheres-Part 1: Equipment-General requirements and the international standard IEC 60079-0:2017 Explosive atmospheres-Part 0: Equipment-General requirements directly cite the radio wave explosion-proof safe power and energy threshold specified in the European standard CLC/TR 50427:2004. But the continuous radio wave explosion-proof safe ignition power threshold is incorrectly modified as the product of the effective output power of the transmitter and the antenna gain. This leads to the reduction of the continuous radio wave explosion-proof safe transmission power threshold. Under certain transmission attenuation and reception sensitivity conditions, the wireless transmission distance is reduced. This is not conducive to the promotion and application of mine wireless communication system and personnel positioning system. Therefore, the safe power threshold for continuous radio wave explosion-proof specified in national standard GB/T 3836.1-2021 and international standard IEC 60079-0:2017 should be the ignition power threshold, not the product of the effective output power of the transmitter and the antenna gain.
2023, 49(2): 6-13.
doi: 10.13272/j.issn.1671-251x.18061
Abstract: At present, there are some problems in the construction of the intelligent mine, such as the non-uniform interface protocol and the formation of new "information island". They lead to the difficulty of data fusion and sharing in mines and the difficulty of realizing the high-quality development of intelligent mine. It is pointed out that the key problem of mine intelligent construction lies in the lack of standardized and unified data acquisition, transmission and sharing standards. According to the core specification, application specification, and operation and maintenance specification, the technology system of intelligent mine communication interface and protocol is designed. The communication interface and protocol model of intelligent mine is proposed. The perception layer, transmission layer and application layer of the model are defined. The model of intelligent mining equipment is constructed, and the communication interface is described formally. The intelligent mine data is divided into perception data, text data and audio-visual data. The message structures of the three kinds of data are defined. According to the current mining equipment, technology application and development direction, the intelligent mine data acquisition modes are divided into equipment direct acquisition, protocol conversion acquisition, and system transfer acquisition. The application scenarios of three data acquisition modes are pointed out. The acquisition and transmission process of perception data, text data, and audio-visual data are described. The technical specification of intelligent mine communication interface and protocol covers the whole process of mine data fusion communication. It provides unified interface mode and communication protocol specification for intelligent mine data acquisition, transmission, fusion and sharing. And it realizes interconnection and intercommunication among various systems of the mine.
2023, 49(2): 14-22.
doi: 10.13272/j.issn.1671-251x.18020
Abstract: The existing mine moving target positioning system has the problems of serious attenuation of underground wireless signal transmission, large non-line-of-sight error, complex underground electromagnetic environment, wide sensing range of dynamic and static targets, strong linkage of multi-system information fusion, etc. At present, the research on mine moving target precise positioning technology and optimization method does not comprehensively analyze the characteristics and technical requirements of the moving target accurate positioning service. It lacks a comprehensive comparison between the mainstream and emerging positioning technologies. In order to solve the above problems, the advantages and disadvantages of the common signal transmission technology and the positioning and ranging method applied in the mine moving target precise positioning system are analyzed. The radio positioning technology is pointed out to be a more suitable and feasible mine moving target precise positioning technology. This paper analyzes the research status and existing problems of the optimization method of the mine moving target precise positioning in China from four aspects: signal anti-collision technology, error elimination method, positioning result optimization method and fusion positioning technology. ① The comprehensiveness of the signal anti-collision algorithm still needs to be improved. ② The efficiency of ranging error control means needs to be improved. ③ The application of the fusion positioning method in the production site is not yet mature. ④ The auxiliary role of the system in emergency rescue is not fully played. In view of the shortcomings of the existing technology, the development trend of the mine moving target precise positioning technology is proposed: ① It is suggested to study the signal collision mechanism and post-conflict recovery mechanism in dynamic environment, and design a comprehensive signal anti-collision scheme. ② It is suggested to research precise, efficient and economical ranging error control scheme to save communication costs. ③ It is suggested to study dynamic positioning scheme design with deep integration of multiple positioning methods to improve the reliability, flexibility and applicability of the system. ④ It is suggested to study the multi-system linkage scheme and the emergency communication and positioning recovery mechanism in extreme cases, and give full play to the role of the system in emergency rescue.
2023, 49(2): 23-30, 55.
doi: 10.13272/j.issn.1671-251x.2022120050
Abstract: The comprehensive control of coal mine disasters is a key problem to be solved in the process of intelligent mine construction. It is an inevitable requirement for the construction of intelligent mines to realize the normalization control of coal mine disasters with the help of digital twin technology. Based on the connotation and essence of the digital twin, this paper analyzes the recognition rule of the digital twin and puts forward the application mode of digital twin technology in coal mine disaster research combining with data interactive process of mine disaster digital twin. Real-time monitoring is carried out by coal mine underground disaster monitoring sensor. The monitoring data is uploaded to the cloud through the edge communication module and cloud communication module. The digital twin numerical simulation software is deployed in the cloud. The monitoring data uploaded by the sensor is used as the initial condition parameter, boundary condition parameter and effect verification parameter. The best optimization parameters and solutions are sought through real-time simulation analysis and continuous trial and error. When the technical means are mature in the twin world, they can be used to analyze, judge and make decisions on the best parameters and solutions for virtual entities. The decision instructions can be sent to underground actuators to control the action of disaster prevention equipment. This paper discusses the practical application of digital twin enabling disaster predictive management and control from three aspects: disaster monitoring scheme optimization, disaster rehearsal and precise planning of disaster avoidance route, and post-disaster rescue scheme formulation and accident investigation. Based on the "cloud-pipe-edge-end" architecture of the industrial Internet, the digital twin service system for coal mine disasters is constructed. The key technologies of digital twin for mine disasters are analyzed. The technologies include intelligent sensing and execution equipment for coal mine disasters, simulation software for coal mine disasters and common support technologies. It is expected to provide reference for the construction of digital twin-enabling intelligent mines.
2023, 49(2): 31-37.
doi: 10.13272/j.issn.1671-251x.18066
Abstract: The straightness problem is one of the neck problems in the intelligent construction of the fully mechanized working face. The key to solve this problem is to obtain the position and posture of the scraper conveyor or hydraulic support group. At present, most of the research on the straightness of fully mechanized working face is to discuss the straightness of hydraulic support and scraper conveyor separately. There are problems such as high cost and difficulty in implementation. In order to solve this problem, based on virtual reality(VR) and digital twin(DT) technology, the method to solve the straightness problem of the fully mechanized working face is explored. The hydraulic support, floating connection mechanism and scraper conveyor are considered as a whole system. The straightness solution framework of the fully mechanized working face is built. There are mainly five steps: mechanism analysis, model construction, fusion deduction, reconstruction monitoring and predictive control. It is pointed out that the key to the analysis of the relative position relationship of the fully mechanized supporting equipment is the floating connection mechanism connecting the hydraulic support base and the scraper conveyor. According to the motion characteristics of the floating connection mechanism, it is simplified into a robot model and solved by forward and reverse motion. According to the real coal seam environment, the motion simulation model of fully mechanized mining support equipment based on joints is established in Unity3D, and the VR scene is constructed to realize virtual and real mapping. Through non-contact visual sensor, virtual sensor, virtual-real fusion and other technologies, the information of sensor and point cloud are fused to perform the position and posture deduction of support equipment. Using the technology of virtual and reality interaction, combined with a real physical scenario, a DT system is constructed to achieve virtual monitoring of the fully mechanized working face. The travel distance required to ensure straightness is predicted in the virtual scene and fed back to the physical scene for straightness control.
2023, 49(2): 38-46.
doi: 10.13272/j.issn.1671-251x.2022040019
Abstract: Based on the basic concepts and connotations of digital twin, this paper analyzes the application advantages of digital twin technology in coal mine power grid. The operation management of the coal mine power grid is assisted by two means of synchronous entity operation status and digital simulation operation. The technology has the characteristics of data-driven, real-time update and synchronous feedback. The basic framework of the digital twin system of the coal mine power grid is proposed. The framework is composed of physical entity layer, digital twin model layer, user service management layer and data exchange layer. The operation mode of the digital twin system of the coal mine power grid is explored from two aspects of the physical entity and the digital twin model. This paper introduces the key technologies for establishing the digital twin system of the coal mine power grid. The technologies include digital twin model construction of coal mine power grid, intelligent data acquisition, intelligent communication based on 5G, digital twin intelligent database, and digital twin equipment intelligent management platform. The application scenarios of digital twin technology in the coal mine power grid are proposed. The scenarios include the condition evaluation of underground electrical equipment, fault location and protection of the coal mine power grid, intelligent monitoring of the coal mine power grid and intelligent inspection of underground lines. The digital twin technology is applied to the coal mine power grid to carry out dynamic simulation modeling on the state and operation of the coal mine power grid. On the one hand, the higher operation requirement of the current large-scale coal mine power grid relative to the ground power grid can be met. The safety of coal mine production can be guaranteed. On the other hand, the intelligent process of the coal mine power grid can be promoted. The efficient and reasonable utilization of data resources can be realized.
2023, 49(2): 47-55.
doi: 10.13272/j.issn.1671-251x.2022120061
Abstract: The existing coal mine equipment digital twin modeling method mainly focuses on single equipment modeling. It lacks three machine coupling collaborative relationship analysis. In order to solve the above problems, the paper puts forward three machine digital twin and collaborative modeling method for fully mechanized working face. By adopting an intelligent modeling method, the method constructs agent-based models of a coal mining machine, a hydraulic support and a scraper conveyor which comprise a sensing unit, a control unit and an execution unit. The method constructs corresponding visual models according to a three-dimensional modeling process. The method drives the three-dimensional models to move by the intelligent models. The combination of the two forms a digital twin model of three machines. A discrete event modeling method is used to construct a collaborative process model covering the interaction process of the three machine digital twin model. The three machine mining process is sorted out according to the time sequence to form a three machine collaborative process time sequence table. The digital twin model is used to describe the state and behavior of the three machines in fully mechanized mining and to simulate the calculation at the individual level. The collaborative process model is used to represent the sequential action transformation between digital twin models and realize the deduction of the whole three machine collaborative process. The simulation of rocker lifting and lowering for the digital twin model of the shearer is carried out. The simulation results show that compared with the measured data of real equipment, the model error is small, an average error of rocker arm dip angle is 2.3°. The simulation of continuous column lifting action for the digital twin model of hydraulic support is carried out. The simulation results show good consistency between the model and real equipment. Compared with the measured data of the real equipment, the average angle error is 0.14° and the average stroke error is 6.3 mm. Combined with the actual production log of the coal mine, the virtual and real simulation experiment of the three machine collaborative model is carried out. The results show that the three machine digital twin model of the fully mechanized working face and real equipment realize mutual mapping. The simulation results are close to the real records. The three machine collaborative model can accurately reflect the collaborative mining process. The method of three machine digital twin and collaborative modeling for fully mechanized working face provides a new idea for the digital twin modeling of fully mechanized coal mining equipment and its collaborative relationship.
Digital twin system architecture and key technology of following process for fully mechanized mining
2023, 49(2): 56-62, 76.
doi: 10.13272/j.issn.1671-251x.18055
Abstract: The process design and parameter debugging of automatic following machine for fully mechanized mining are costly, time-consuming and cumbersome. In order to solve the above problems, the digital twin system architecture of following process for fully mechanized mining is proposed. The study analyzes the aspects of physical equipment, virtual and real interaction, twin data, mechanism model, simulation algorithm and process application. The key technologies such as the transmission and storage of the following process data, the playback of the following process history, the real-time following process twin deduction, the rehearsal simulation of following process, and the instruction scheduling of following process are described in detail. The paper puts forward the technical roadmap of the digital twin system of following process for fully mechanized machining. Through 10 Gigabit optical fiber ring network+5G communication, the shearer process action data is collected to the shearer host. The support process action data sent by the serial support controller is collected to the electrohydraulic control host. The process data is collected, classified and coded according to the action sequence as the data source for the playback of the process. At the same time, the host computer forwards the real-time reported following process data to the 3D digital twin system. The twin system deduces the following process in the 3D virtual scene. After the following process parameters are configured on the human-computer interface, the following process for fully mechanized mining can be previewed in the 3D scene. During the real-time mining process, the system will collect all kinds of sensor data and issue process scheduling instructions in combination with the rehearsal of error-free following process. The support controller is changed from a decision-maker to an executor to overcome the limitation of the limited computing power of the controller due to the lack of underground space. The field application results show that the digital twin system can provide technical reference for the process design, parameter configuration and simulation test of following process for fully mechanized mining. The system can shorten the development cycle of the following process from 14 days to 1 day, making the modification of the following process design more convenient. The system improves the following automation rate in working face to more than 90%.
