煤矿环境定位检测系统外文翻译

1、附录 A 外文文献A Coal Mine Environmental Monitor System with LocalizationI. RESEARCH STATUSAs an important energy, coal plays a pivotal role in the economic development.Coal mine monitoring system, is the important guaranteefor coal mine safety and high efficiency production. In order to ensure the safe o

2、peration, the installation of environment monitoring node in tunnels to real-time detection is very important. However, commonly used traditional monitoring node wired connection to obtain communication with the control system, this node exist wiring difficulties, expensive and other shortcomings. I

3、n contrast, wireless sensor node can be easily with current mine monitoring network connection, and good compatibility, facilitate constituted mine gas monitoring network, to suit various size of mine applications. Since wireless nodes are battery powered, so completely out of the shackles of the ca

4、ble, shorten the construction period can be arranged at any time where the need to use.The Zigbee wireless communication technology is used in this coal mine environmental monitor system. This is a new short-range, low complexity, low power, low data rate, low-cost two-way wireless communication tec

5、hnology. Now, wireless sensor network product based on Zigbee technology are quantity and variety, but the real product can be applied in underground environments of special sensor node is very few. The sensor node that we designed in the system is truly able to apply to in-well environment, it thro

6、ugh the wireless sensor node security certification. At the same time, due to the special nature of the wireless network is that it can spread the wireless signal, we can easily locate staff for coal mine safety monitoring provides more protection.II. SYSTEM ARCHITECTUREThis system is a comprehensiv

7、e monitoring system which is combined with software and hardware. Hardware part includes wireless mobile nodes and fixed nodes which were deployed in the underground tunnel, the main function of them is to collect coal mine environment data and require person s location. Software part refers to the

8、PC monitoring software which is designed in VC+ is used to summarize anddisplay the data of each node. Monitoring node is divided into mobile nodes and fixed nodes; they are using Zigbee protocol for wireless transmission of data. Because the fixed node is also using wireless data transmission metho

9、d, so its deployed in the underground roadway becomes very convenient. As the mobile node is carried by the miner, it must be using wireless transmission method. This allows the mine to form a topology of Zigbee wireless sensor network. The fixed node in wireless sensor network is router device and

10、the mobile node carried by miner is the end device. Normally, the router of Zigbee network has no sensor equipment; it is only responsible for data forwarding. But considering the practical application, we believe that add sensor devices on the router will be better on monitoring underground coal mi

11、ne environment. So in our design, the router also has an environment monitoring function which is usually designed in end device.s realFixed node will sent received data from mobile node to the gateway, then the gateway transmits data to monitor computer through RS232 or optical fiber. The PC monito

12、r software in the computer will process all data and display them in a visualization window. The PC software also calculates each mobile node-timelocation through the specific localization algorithm, according to the received signal strength (RSSI) obtained from mobile nodes.III. NODE DESIGNSince th

13、e Zigbee wireless network platform sold on present market was designed for the general environment, for special underground so they are not suitable for the environment. Therefore, we need to customize the system for underground environment whit a special hardware circuit. Node photo are shown in Fi

14、g. 1Then wireless microcontroller CC2530 chip is the core processor of the node device, it can constitute a Zigbee network with very few peripheral circuits. The CC2530 is an IEEE 802.15.4 compliant true System-on-Chip, supporting the proprietary 802.15.4 market as well as the Zigbee, Zigbee PRO, an

15、d Zigbee RF4CE standards. Unlike other wireless chip, CC2530 built-in 8051 monolithic integrated circuits kernel, therefore we no longer need to use a single MCU to control the circuit, and this save us a lot of cost.A. Mobile NodeThe mobile node is the end device of a Zigbee network that can be car

16、ried by miner; it should be a portable and low power consumption node. So the mobile node we designed is only as small as a mobile phone, and it is by built-in lithium ion battery power supply. In power loss, the core processor CC2530 is a low power consumption chip, when it is in the sleep mode, it

17、 only need to use less then 1uA work current. In order to reduce power consumption as much as possible on the display, a 100*32 pixel matrix with no backlighting LCD screen was used. The battery s capacity of the mobile node is 1500mAh, so it is enough to meet the miner long hour works in the underg

18、round. The battery charge management chip is TP4057, the maximum charge current can up to 500Ma.The mobile node circuit includes the gas concentration sensor MJ4.0 and temperature sensor PT-1000. As far as we know, many wireless sensor platforms use the digital type sensor. The communication between

19、 the digital sensor and the MCU need strict timing requirements. But considering the actual application, the wireless MCU usually has a real-time operating system in general, if we use the microcomputer to simulate the strict timing, it will affect the real-time of whole operating system. These two

20、sensors output analog signals not digital signals. Only input this signal into a differential amplifier, can we get an appropriate signal that can be converted to a digital signal by an ADC mode within the CC2530 chip. In order to facilitate the carrying, external antenna was not used in our mobile

21、node, instead of using a 2.4GHz patch antenna. And we customize a shell like a cell phone size; it is enough to put all PCBs, sensors and battery in it. Taking into account the small shell of the explosive performance is not very good, the design of PCBs and the selection of component are all carrie

22、d out the safety assessment.B. Fixed NodeFixed node is installed in the wall of the underground tunnel. Because it is big than the mobile node, it is not appropriate to carry around. The circuit of the fixed node is almost same with the mobile node, it also use a CC2530 chip as core processor. Becau

23、se of underground tunnels generally deploy with power cable, fixed nodes can use cable power-supply modes. At the same time, because we use wireless signal transmission, the deployment of new fixed nodes become very convenient, which also resolves the problem of the signal lines deployment.As a fixe

24、d node, the minor who is doing work may far from it, in order to facilitate the miners observed environmental data around the fixed nodes, it uses LED digital display. At the same time, the large current LED lights and buzzer are designed in the circuit; it makes the fixed node with the function of

25、sound-light alarm.Considering that it may occur the emergency of without electricity, fixed node also built-in a lithium-ion battery. Under normal conditions, lithium-ion battery is in charging status, when external cable disconnect, fixed node is automatic switched to battery power, which can ensur

26、e the mobile node can deliver the information through fixed nodes in underground.Without regarding to fixed nodesportability, we have a customized shell that has excellent explosion properties, and the internal space is enough to hold down the 2.4 GHz antenna. To ensure safety, all cables and the lo

27、cation of sensors are placed with particular glue sealed, so that it has a good seal.IV. POSITIONING FUNCTIONOne of the important functions of the wireless sensor networks is localization, especially in the underground tunnel, it relates to the safe of the miners life. Currently most widely used ori

28、entation method is GPS satellite positioning, it is a high precision, all-weather and global multifunctional system with the function of radio navigation, positioning and timing. But the GPS positioning method is not suitable for the underground work environment of coal mine, once you enter the unde

29、rground, it cannot receive satellite signal, thus unable to achieve targeting. We need to consider how to use wireless network to realize positioning function, means using wireless signal between the communications of devices for positioning. The existing distance measuring technology between the wi

30、reless-devices basically is the following kinds of methods: TOA, TDOA, AOA and RSSI.About the TOA method, the distance between the two devices is determined by the product of the speed of light and transmission time. Although the precision of this method is accurate, but it require a precise time sy

31、nchronization, so it demand hardware is higher.TDOA technology need ultrasonic signa，l which is setting on a node with receive and transmit function. When measure the distance, it can sent ultrasonic wave and wireless signals together. By measuring the difference between two signals arrival time, we

32、 can calculate the distance between two devices. Using this method can also obtain accurate result, but the method need to increase ultrasonic sending and receiving device on the node circuit, it will increase cost.AOA technology needs to install multiple antennas through the nodes so it can obtain

33、adjacent nodes soignndaelsferent directions. With this it can determine the location information from number of adjacent nodes and calculate its own position. This method not only need to add additional hardware, but also its still very vulnerable to external disturbance, therefore its not suitable

34、for utilize.RSSI ranging is a cheap and easy technology. By using this method, we dont need to add additional hardware design. We also do not need very precise time requirements. This technique is about with measuring the wireless signals strength in the propagation of the loss, to measure the dista

35、nce between two nodes. Because of this method requires hardware equipment is less, algorithm is simple, so it has been using in many wireless communication field. Comprehensive all conditions, positioning on the use of RSSI ranging technique.A. Hardware Location EngineThe CC2431 wireless microcontro

36、ller chip produced by TI Company has a hardware location engine. From the softwares point of view, CC2431 shardware location engine has a very simple API interface, as long as writing the necessary parameters and waiting for calculation, it can read the location results.The hardware location engine

37、is also based on RSSI technology. The localization system includes reference nodes and blind nodes. The reference node is a fixed node that located in a known position, the node know their place and send a packet notify to other nodes. The blind node receives packets from reference nodes, which can

38、obtains reference nodes location and thpeoncdoirnregsRSSI value and put them into the hardware location engine, and then the blind node s location can be read from theengine.On the surface, using the CC2431 hardware location engine targeting the program as a good choice, but considering the practica

39、l application, it will encounter the following problems. First of all, we have choose the CC2530 as the main chip of fixed nodes of the system, its internal programs is running in Zigbee2007 protocol, but CC2431 as a early chip, it applies only to Zigbee2006 protocol. In the communications between C

40、C2431 and CC2530 that will have compatibility problems. Secondly, CC2431 hardware location engine use the distributed computing, all mobile nodes location are calculated by themselves, and then they uploafdorinmation to the gateway node, this will not only occupy the mobile node processing time, sti

41、ll it can take up more network resources.For this reason, we have to shelve this approach, consider how to implement location by using CC2530 chip.B. Software Location EngineIf we want to use CC2530 to implement location function, that we must write software location engine by ourselves. Because tha

42、t chip do not have a hardware location engine inside of it. This software location engine is still used RSSI technology; meanwhile mobile node position is calculated by the PC software, so as to reduce the burden of mobile node computing. To calculate the mobile node location, there must be at least

43、 three reference nodes. We will regard router nodes as reference nodes in network, and record the X, Y coordinates of every reference node. Then we let the mobile node send signal to each reference node, so that each reference node can obtain a RSSI values, with these parameters, we can use trilater

44、al measurement method to calculate the specified location of the mobile node. The simpler way give the mobile node to broadcast way to send data, then around it every router node would receive the data from the mobile node, thus obtains RSSI values. Once the mobile node number increasing network, th

45、is method will make router nodes more burden, because the every radio message that the router node receives will transmit from the low layer to the top layer. Finally the application layer will analyze data packets. In fact, the mobile node need not to broadcast transmitted data, other routing node

46、can also receive the mobile node packets. Only child mobile nodes of the router node will continue to transmit the packet forwarding upward, the other router nodes will shield out the packet in the bottom of the protocol.In order to let all router nodes can receive the packet which sending by mobile

47、 nodes, and send its RSSI values up to the gateway node, we need to modify the relevant function in Z- Stack protocol which is provided by TI. First we find the function named afIncomingData, it deals with the received data from the bottom of protocol, in which we add some code that can obtain packe

48、t RsSSI value. Then through the osal_set_event function to add and send an event MY_RSSI_REPORT_EVT of RSSI value task to OSAL polling system. This event corresponding function will be executed in the task of OSAL interrupt-driven function, thus the mobile node corresponding RSSI values will be sent

49、 to gateway node. Through this method, the packet will only be processedby bottom function of the protocol. According to this method we can obtain corresponding RSSI value and save the computation time of mobile nodes.s parent rouIn fact, this software location engine is not implementing with a sing

50、le mobile node, but through the operation of the whole system to achieve. By which the mobile node is only responsible for sending unicast packets. The mobile nodes location isnode is responsible to forward the packet to the gateway. Other router nodes are not responsible for forwarding this packet,

51、 just clipping the mobile node of RSSI value, then forwarded to the gateway. Finally the gateway bring all RSSI values of the mobile node to PC monitoring software, the corresponding mobile node calculated. In order to reduce the error, monitoring software will collect 10 times of the RSSI value and

52、 take average on it, and then select the nearest value of the three fixed nodes. Finally the trilateral measurement method is used to calculate the location of mobile nodes.VSYSTEM IMPLEMENTATIONAll software systems embedded in nodes are based on Z-Stack. Because Z-Stack is an open-source project, i

53、t is very beneficial to the secondary development. These nodes were tested in a real coal mine locate in Shanxi Province. We deployed the fixed node every 50 meters in the tunnel, and also set a fixed node in each entrance of the work area. Because the fixed node have large size digital LED displays

54、, so the display content of the fixed node can be seen far from away the miner. Each miner carries a mobile node, the temperature and gas concentration is displayed on the LCD screen at real-time.The gateway node is placed at the entrance of the mine, through the RS232 cable connected to the monitor

55、ing computer in the control room. In this system all packets collected by the gateway node are transmitted to PC through a serial port, and it can save historical data backup to a SQL database. The main function of monitoring software is to display and store the data of every node, and calculates re

56、lated mobile nodeslocation according to RSSI values. The monitoring software has two main dialog interfaces, one is used to display a two- dimensional profile of the coal mine, and user can see all the miners working position. Another interface is data displaying interface, and environmental data we

57、re shown here. The picture of PC monitoring software is shown in.VI SYSTEM EVALUATIONThrough repeated testing of the system, we made the system an objective assessment.First is the power consumption assessfor node hardware, fixed node s working voltage is in 9V 24V when the power supplied by cable.

58、The maximum operating current for fixed node is 93mA; the average operating current is 92.2mA.When the power cable was disconnected, fixed node powered by lithium-ion battery. On battery power, the fixed nodems aximum working current is 147mA; average working current is 146.3mA. Fixed nodes can work

59、 8 hours on battery power at least.Another quite important performance is the location function of the system performance. At four different locations of tunnel and working areas, mobile nodes were placed there. Two sets of different average error data were shown in From table 1. Because this system uses RSSI technology and it relies mainly on the signal strength, the signal quality will be affected by interferences. From different locations errors