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综放工作面快速过断层技术研究.rar

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    IEEE MTT-S International Microwave Workshop onWireless Sensing, Local Positioning, and RFID (IMWS 2009 - Croatia)978-1-4244-5062-6/09/$26.00 ©2009 IEEEWireless Sensing Applications in the Mining and Minerals IndustryKarl Nienhaus ∗, Martin Hahn ∗ IEEE Member, and Reik Winkel #∗ RWTH Aachen University, Excavation and Mining Equipment Group (BGMR), Aachen, Germany# indurad GmbH, Aachen, GermanyAbstract— This paper discusses and outlines applications of wireless sensing technology in the mining and minerals industry to provide enhanced assistance to mining machines. Three major applications can be performed by radar systems, such as surface profiling, positioning and collision avoidance. Radar sensors offer significant advantages compared to laser and ultrasonic in tough environments like rain, dust, fog and snow. The information received from the sensors can be used to increase the automation level and to advance the safety in the mine plus furthermore increase the turnover of mining companies.Underground communication systems and machine diagnostics are also discussed in this paper. Several applications were determined as highly feasible and are now completed respectively in the implementation stage. The authors are giving an insight into the experimental results, the implementation and an outlook of further use for this technology.Index Terms— wireless sensing, radar, RFID, digital beam- forming, mining applications.I. INTRODUCTIONThe global output of mineral material is continuously rising, while the number of fatal and non-fatal injuries decreases according to various sources [1]. The reason for these trends derives from the increasing level of assistance and automation technology on large and complex mining machines. New systems help to improve the safety of the operating staff and the productivity of mines. In many cases processes that need to be controlled, can not be handled by an operator or are too dangerous to be accomplished by a human. Thus wireless assistance systems are frequently used to prevent accidents like shown in Fig. 1 and to support process control. Besides, wireless diagnostic systems help to determine the abrasion wear and are used for material detection, too.Section II presents a brief summary of processes in the mining Upper left: bucket wheel/chain excavator, Upper right: Truck and shovel, Lower left: longwall with shearer loader, Lower right: Mobile haulage with LHD- vehicle.A. Surface OperationsSurface mining also referred to as open-pit mining com- prises mineral resources that are located near the surface, where the resource volume is large.It can be realized with a continuous mining process using a bucket wheel excavator (see upper right in Fig. 3), that removes the overburden covering the desired raw material on the upper levels. Further excavators remove the valuable material, e.g. lignite. If needed the overlaying material is loosened by explosives (drill & blast method). Big machines like draglines, hydraulic excavators or rope shovels, load haul trucks with a load capacity up to 360 metric tons that transportIEEE MTT-S International Microwave Workshop onWireless Sensing, Local Positioning, and RFID (IMWS 2009 - Croatia)978-1-4244-5062-6/09/$26.00 ©2009 IEEEbetween hopper car and belt structure [3].the material to a crusher and to further facilities.B. Underground OperationsUnderground mining involves mineral deposits, which are located in large depths or deposits with high local concentra- tion. Continuous mining processes involve longwall mining while room-and-pillar mining as well as underground hard rock mining can be considered as discontinuous processes. Longwall mining is considered to be the most effective mininge. g. on a hopper car (see Fig. 3).In a lignite mine the hopper car transfers raw material from the bucket wheel excavator onto a 5 km conveyor belt. During testing phase parts of the steel belt structure could be detected with high precision of below 0.03 m. Based on successful experiments two pairs of sensors were installed permanently on the hopper car to automatically control the lift-distancemethod for large flat deposits. Roof support shields (compare 3lower left in Fig. 2) prevent the hanging roof from falling onto the cutting machine. After cutting the material it is transported by the AFC (Armoured Face Conveyor) to the next crusher and then further fed to the shaft. Usually roads are cut byIndurad Radar1 Hopper Car2Conveyorroad headers or continuous miners.Besides longwalls as a continuous mining method, in discon- tinuous operations mobile mining equipment like continuous miners, LHD (load, haul, dump)-vehicles, drill riggs and oth- ers are used.C. Environmental Conditions and Operational ConstraintsTo differentiate the application parameters they are divided into environmental conditions and operational constraints. Sen- sors need to be designed for rough mining environments, since the environmental conditions cannot be modified as easily as in a factory.Most of these environmental factors are not quantified by standards or regulations. Only working temperatures and rel- ative humidity values should be in the range of −25 ◦ C and+65 ◦ C and a rel. humidity around 100% respectively. Due to ice and snow on sensors or disturbances caused by rain, fog, wind, high/low temperatures, mud, dust or vapours factory- designed sensors often fail, which results in a dramatic drop of the machine availability. Sensors on machines are required to follow standards concerning water, dust and mechanical damage.For the use in mobile machines all components have to pass many operational conditional tests. Vibrations and shocks can be expected in all six directions with different amplitudes and accelerations of several g-forces. The influence of electromag- netic disturbance due to power supplies and electronics has to be considered. Electrical components must be hardly or non inflammable according to the MSHA (Mine Safety and Health Administration) and ATEX (Appareils destine´s a` eˆtre utilise´s en ATmosphe`res EXplosibles) regulations and either intrinsically safe or flameproof protected. They also have to be easily displaceable and installable.III. IMPLEMENTED SOLUTIONS AND CURRENT PROJECTS OF WIRELESS SENSING IN THE MINING & MINERALS INDUSTRYA. Positioning (Example: Hopper Car)Radar technology is used predominantly for process au- tomation in mining because of the robustness against dust, fog,TMBucket Wheel Excavator2Loading Table3Belt FramesFig. 3. Radar installation on a hopper car in the Rheinisch lignite mining industryRaw data from the sensors is transferred via CAN-Bus to an industrial PC (IPC), where the data is filtered according to different ancillary conditions and stabilised with statistical methods and send to a PLC drive controller [4].The experiences gained during the automation project of a hopper car is currently being transferred to other applications, such as:• parking assistance of haul trucks during loading phase at shovels• dumping positions at crushers• positioning of hot machinery in steel millsB. Collision Avoidance (Example: Shearer Loader)Wireless radar sensor solutions are as well used to prevent accidents and damages. Such a system has been installed on a shearer loader to prevent collision between the arm/drum of the shearer and the roof supports. In a longwall high levels of dust, mist and moisture are present, while vibrations and shocks stress electronic components installed on the machine. Within a two year automation project, sustainable knowledge on multipath propagation was gained on the implementation of microwave radar systems in a massive iron environment. After comprehensive tests at a longwall in the German Mining Test Rig in Bochum and at a training coal mine, a 77 GHz radar sensor has been selected, mainly because of the small antenna size and beam-forming. Using automotive sensors signal pro- cessing algorithms had to be optimized in order to get verysnow and rain [2]. The indurad Dual Range Radar (iDRR) detailed and high resolution data from the sensor. Additionallysensor has been applied to solve various positioning problems, a flameproof protection radar box with special radar absorbersIEEE MTT-S International Microwave Workshop onWireless Sensing, Local Positioning, and RFID (IMWS 2009 - Croatia)978-1-4244-5062-6/09/$26.00 ©2009 IEEEthe line between coal and waste rock [3].2 mfor side-lobe suppression has been developed by the shearer manufacturer Eickhoff. The system is now implemented at Auguste Victoria underground coal mine in Germany. Besides, the shearer has been equipped with floodlights, a video camera and infrared based boundary layer detection sensors to identifye. g.:• belt volume flow measurement (see Fig. 5)• slope profiling• bin filling level• railcar loading• ship loading# 228 # 223 #222 # 221 # 2201.75 m3 m2 m1 m0 m2.09 m 1.96 m 1.92 m 1.87 mFig. 4. Schematic view of a longwall with the shearer and prospective collision objects (roof supports)Collision avoidance systems using microwave technology are also developed for nearly every stationery and mobile equipment in a mine (above and underground). Further ap- plications are currently worked on concerning:• shovels and excavators• auxiliary vehicles• bucket wheel excavators• continuous minersC. Surface Profiling (Example: Conveyor Volume Flow)In contrast to 1D-level gauge radar systems of established manufacturers the 2D-iDRR measures not only linear dis- tances, but two-dimensional surface profiles, within 0.066 s at a range of > 100 m and an accuracy of better than 0.05 m. The detection range is divided in a high and medium accuracy sector. Usually the high accuracy sector is used for surface profiling, the medium accuracy for collision avoidance. The antenna principle is based on a spinning grating antenna, that influences RF power dependently on the depths and distances of grooves on the drum’s surface. Due to the changing drum surface around the circumference, the sensor radiates RF power depending on the grooves [5].For mining usage the sensor itself is installed in a robust IP67 aluminium casing. The raw data of the radar sensor is processed on an IPC. The open architecture allows any kind of interfaces like: Ethernet, CAN-Bus, ProfiBus, RS232 or others. The data can be transferred directly to the plant, e. g. for automation issues, visualized on a screen for operators or within a corporate intranet.The sensor has been successfully approved in a number ofimplementations. Further applications are currently worked on,Fig. 5. Application: mass flow measurement, left: Using the iDRR and a laser scanner in parallel the effect of dust can be visualized, right: A 10 min measurement shows that accurate measurement results and minimal variances could be achieved during the operationD. CommunicationFor data communication from the surface control room to an underground shearer loader in a longwall powerline modems are applied, occasionally also fiber optic cables are implemented. In order to prevent a connection breakup and to assure a secure connection a redundant data connection was needed.A new approach has been the installation of a redundant communication system including WLAN connections in the longwall. In order to assure an independent and redundant data connection with the shearer WLAN access points (AP) were installed on the roof supports along the longwall (compare Fig. 6 AP1 to AP4). In addition the shearer was equipped with a WLAN client.As the shearer moves along the longwall, the client on the shearer measures the signal strength of the different access points and connects to the AP with the best signal quality. In the challenging steel environment for WLAN the standard IEEE 802.11g has been installed. Using specially defined roaming procedures handover-times from one AP to another AP could be reduced down to 2.6 ms. Every component had to be either intrinsically safe or flameproof protected. Eickhoff achieved the installation of a working redundant wireless connection in a longwall environment. Currently this system runs in an underground coal mine in Slovenia and Australia. Future concepts of wireless communication systems are discussed in section IV.IEEE MTT-S International Microwave Workshop onWireless Sensing, Local Positioning, and RFID (IMWS 2009 - Croatia)978-1-4244-5062-6/09/$26.00 ©2009 IEEEFig. 6. Concept of redundant shearer network using WLANIV. REMAINING CHALLENGES FOR WIRELESS SENSING IN THE MINING & MINERALS INDUSTRYA. Exploration Using Ground Penetrating RadarOver the past three decades various applications for ground penetrating radar (GPR) have been investigated. Applications range from archaeology to outer space analysis of planets. GPR also found its way into mining, but is according to mining companies yet an undependable method for explo- ration. However there are some companies who investigate mineral deposits, sometimes in combination with drilling. Further development and new antenna concepts could improve the benefits of GPR for mining.B. Underground NavigationAn enormous challenge for underground mining is navi- gation. Since there is no global positioning system (GPS) available and the environment is always changing, adaptive navigation methods are needed. Underground drifts are always changing due to outbreaks and mine subsidence. Additionally new drifts are opened and old ones are closed for usage. Therefore adaptive multi sensor systems are needed that use many different kinds of sensors, e. g. odometers, gyroscopes, laser and radar scanners. Laser scanners are very accurate, but fail in dusty and moistly environments. Instead radar sensors perform well under such conditions. Navigation issues come up in many different applications in underground mining, e. g. at LHD-vehicles, on box hole borers or on pickup trucks that transport miners and goods.C. Machine DiagnosticsIn order to receive diagnostic information from machines wireless sensing could be used. One approach of such a system started at the BGMR group of the RWTH Aachen University developing the Wireless Cyclic Stress Sensor (WCSS). Using radio communication in the ISM band, mechanical stress val- ues can be transmitted from a mechanically stressed machine part to a receiver. Using a specially developed tool it is then possible to predict the lifetime of the machine part.D. Wireless Underground CommunicationAs mentioned in section III-D WLAN has been imple- mented for underground applications. In order to improve the availability of WLAN underground the leaky feeder had been developed. Up to now this system has a limited rangeand cables have a limited flexibility. Universal communication system
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