基于zigbee技术的煤矿报警系统的应用研究

Application Study of Mine Alarm System Based onZigBee TechnologyWANG Qingzhu, LIU Rongchang, MA Yuquan,ZHAO Jinchuan, FENG Lizhen, LIU ShiguangHebei Normal University of Science & TechnologyΔQin huangdaoΔHebei ProvinceΔChinawqzh101@Abstract – After intro ducing the wireless networkco mmunicatio n techno lo gy ZigBee and the features, advantages and applicatio n rule o f the wireless single chip micro co mputer cc2430ˈwhich is a true system-o n-chip (SOC) lo ading ZigBee techno lo gy, the article intro duced the design metho d o f mine alarm system based o n ZigBee techno lo gy. The co mpo sitio n o f the mine alarm system and the design features of hardware and software were expounded mainly.Index Terms - Co mmunicatio n Techno lo gy ZigBee Mine alarm W ireless networkI. PREFACEAt present, detector widely used in mine is all single testing, artificial observing and recording. It is inconvenient for centralized management and analysis of data and for the analysis of the distributing gradient of harmful gases to find out the source and tendency[1]. Although detection and alert system of a few mines have built up the cable network, the mine tunneling and mining is dynamic, and the cable network can hardly adapt to this case. So using ZigBee, a technology of short range wireless network communications, which is brand-new, of low-power, low cost, low complexity and low rate, the scientific research group develops the mine alarm system which is neatly constructed and reliably operated.II. A SUMMARY ON THE ZIGBEE WIRELESSCOMMUNICATIONS TECHNOLOGYThe ZigBee technique[3] including the IEEE802.15.4 standards[2]is a newly-developing wireless network communications technology. It doesn’t exist a long period of time, and the specifications of its version 1.0 are released by the ZigBee alliance at the end of 2004, its commercial operation and application haven't been cosmically deployed. But, its upswing is obvious. It is predicted that the products & application based on ZigBee will gain rapid popularization and rapid development in the near future.A. The main characteristic of the ZigBee technique[4]1) The low-power. Under low standby power mode, two No.5 dry batteries can work 6̚24 months for one node, even longer. This is an outstanding advantage of the ZigBee.2) The low cost. It reduces the request of Communication Controller by simplifying agreement (less than one tenth of Bluetooth)[5], according to prediction analysis, the full-function main node needs the 32 KB code, the sub function node at least the 4 KB code and the ZigBee does not need an agreement patent fee with 8-bit 8051 micro-controller estimation.3) The low speed rate. The ZigBee works at 250 kbps communications speed, so it meets the application requirement of data transfer at a low rate.4) The short distance. The transmission ranges from 10 to 100 meters and may increase from 1 to 3 kilometers by advancing the RF transmitting power. This is the distance between adjacent nodes. Through communications relay between routes and nodes, the transmit distance will be farther.5) The short time delay. The ZigBee has relatively fast response speed, generally, it will spend 15ms converting from sleep state to work state (the Bluetooth needs 3̚10 seconds), and it only takes 30ms for connected nodes to link and enter the network, and the power has been further saved.6) The high capacity. The ZigBee can adopt the network structures of the star, slice and mesh, and a main node manages some sub-nodes, at most 254; at the same time, main nodes can be managed by upper-layer network nodes, which can constitute a big network consisting 65000 nodes at most.7) The license-free frequency band. Direct sequence spread-spectrum at 2.4 GHz (the world) (ISM), 915 MHz (the United States) and 868 MHz (Europe) is applied in industrial, scientific and medical frequency band.It is these bran-new characteristics that makes the ZigBee technique be widely used in the fields such as the wireless digital transmission, wireless sensor network, radio-frequency identification, the safety monitoring, and industry automation, etc.B. The system on a chip ( SOC ) Loading the ZigBee techniqueThe cc2430, a system on a chip ( SOC ) loading the ZigBee technique produced by Cypress Company, is a kind of wireless single chip microcomputer, it is an integrated System-radio frequency transceiver, as is shown in figure 1. The main characteristics of the CC2430 are as follows:978-1-4244-2503-7/08/$20.00 © 2008 IEEE1) Based on specialized design, all the high frequency circuits needed by ZigBeeIEEE 802.15.4 technology standard are integrated into the built-in circuit. Between wireless single chip microcomputer and antenna, there are only 3-5 0603 ordinary elements.2) By using a special design, the perfect match between the 8051 Microprocessor and the high frequency circuit is achieved in way of designing a titchy chip (48 pin and 7*7square millimeter ), which includes high speed 8051 Microprocessor, flash from 32K to128K, manifold Peripheral Circuits for 8k SRAM, 8 to 14-Bit A/D Converter, RTC, CC2420 wireless chip, and so on, so that the wireless ness and microminiaturization of SCM are truly realized, as is shown in figure 1.3) A great deal of software processing is needed in the wireless communications, including debugging, prevention of packaging collision in the air, the IEEE 802.15.4 standard communications agreement processing, network route, various network topology etc., which can be easily put into internalblocks, because the new-generation wireless single chip microcomputer, like CC2430, requires larger memory space, taking CC2430-F128 as an example, if the IEEE 802.15.4 agreement software is stored, only about a quarter of the memory space is needed; if the complete ZIG BEE wireless network agreement is stored, only one-half of the memory space is needed, and we still have enough space to save our applied code.4) The very low power: In sleeping mode, CC2430 consumes only 0.9 ȝ A, and the system can be awakened by external-interruption or RTC; and it consumes less than 0.6ȝA in waiting mode, and the system can be awakened by external-interruption. In receiving and transmitting mode, it consumes less than 27m A and 25m A respectively. The transitory character of CC2430 from sleeping mode to active mode adapt especially to the applications which request long life batteries.5) The very low cost : The CC2430 includes high speed 8051 kernel, the ZIGBEE RF hardware part, the 8 K SRAM and the 128 K/64 K/32K flash, of which $ 2 to $ 4 should be paid in large purchase.From the above-mentioned characteristics, we can see the wireless single chip microcomputer CC2430 lays a solid hardware and software foundation for the construction ofpractical wireless correspondence network.III. MINE ALARM SYSTEM BASED ON ZIG BEE TECHNOLOGYA. Design of the hardware systemThe IEEE802.15.4 standards support various network topology structures, including level divergent chain structure and the structure of measurement and control system with master and slave mode. According to the characteristic of mine alarm system, the system frame designed is shown as figure 2.The IPC accomplishes sending orders, receiving data, synthetic analysis and processing, display and alarm.The coordinator 1000, 2000 , ···n000 are placed in the first outer layer of IPC, which communicate with IPC by the wired correspondence, generally one layer tunnel establishes one or a few axis nodes, each being a coordinator in communications network, as well as a sensor node according to the need, it is responsible for receiving and sending orders,together, and stores the data in self-space in a certain format, then sends to IPC in an appointed form. The work principles and functions of other coordinators are the same—— both being responsible for connecting all the rations and a sensor node according to need.The function of ending sensor node is single, and it is only responsible for collecting and sending data.No matter how big the network is, how many layers it has, it depends on the specific condition. The structure is of clear hierarchies, and easy to extend and programme software, and also solves the problem of c ommunications between the outmost long-distance of network system and IPC by means of relay.1) The hardware structure of network node :Because the system on a chip (SOC) loading ZigBee technique, wireless single chip microcomputer CC2430 has abundant resources and powerful functions, whether the network node placed in the modulator or the sensor node placed in the network ending, its hardware structure is very simple, dependable and practical. The structure frame of coordinator node with collecting-data function is shown as figure 3. Apart from data acquisition and up-loading, it can display alarm messages (including parameter and position) on liquid crystal display ˄LCD ˅ and light emitting diode ˄LED ˅.According to need, the node structure can neatly install peripheral device, the relay node of transmitting data does not need to place sensor and display part; the sensor node of network ending only needs to connect sensors, and the alarming part is not needed. Certainly, it is an integrated safety detecting instrument if it is not fixed but carried by the individual miner .chip :There are RS-232 serial standard interfaces in IPC, and its deferent distance is no more than 15 m[7], but in the mine alarm system, the communications distance between main control room and each tunnel is farther, so the system has designed a RS-485 serial communication card for the IPC, which realizes the conversion from RS-232 to RS-485. The deferent distance of the RS-485 serial standard is 1200 m[7]. The IPC accomplishes the order and data transmission to the CC2430 chip by RS-485 serial communications card, so that it can realize the monitoring and warning to the whole working face. Its conjunction frame is shown as figure 4. After both sender and receiver have carried on the agreement conversion, the RS-485 agreement is relatively transparent to data transmission, so it can still keep on long-distance data transmission and control by using the RS-232 in the PC.B.More and more complex wireless network needs a great deal software codes to manage. So the codes of 802.15.4 standards and ZigBee network are arranged and achieved by the international standard organization and the ZIG BEE alliance [8], then they are provided to the customers with the ZigBee protocol stack (Z-STACK) software library and the source code library mode, including debugging, the IEEE 802.15.4 standard communications agreement processing, network route, and various network topology etc., it is easily put into internal memory of wireless single chip microcomputer like building blocks. Because the ZigBee protocol stack (Z-STACK) is regarded as the core software in the ZigBee technology and as key software and platform in developing 802.15.4/ZigBee technology, the customers complete application design by a series of initialization and high level transfer according to IEEE 802.15.4 standards.Because the new generation wireless single chipmicrocomputer has bigger memory space like CC2430, taking CC2430-F128 (128KB flash memory) for an example, it needs about a quarter memory space if the IEEE 802.15.4 agreement software is stored, it also only needs one-half of the complete ZIG BEE wireless network agreement is stored, we still have enough space to save our applied code. The protocol cluster and application software’s steady run of TSR in the memory can ensure the compactness and effectiveness of the whole ZigBee module[9].The level divergent chain structure of the hardware system decides that the software system is made up of operation procedure of the network node and the IPC.1) The program design of the network node: Though the node structure of various layers, different places and different roles is of flexible configuration according to the need, it causes the difference of application program. But their common ground is that the majority time is placed in energy saving dormancy-time by the software settings (for example 5 seconds) -this is the basic measure of energy saving, only a little conventional period (for example 10 millisecond) accepts the lower layer data packet (except for the network ending node), the A/D conversion, the data calculation and processing, the display and alarm (if needed), and it sends its self-data and the data transmitted by the lower computers to the upper coordinator node in a certain format[10].2) The IPC program design: The IPC regards configuration software [11]as the control software. Configuration software makes use of the platform provided by the system software and carries out software function accorded with the supervision request by fast, simple and visual configuration job.and control instrument 1000,2000 ……n000 placed in the first outer layer as the peripheral equipment, according to "the equipment allocation guide " it completes the conjunction process step by step in the development process. The King View realizes the order/data exchange by drivers and the first outer layer coordinator node during their operation, thereby, the IPC completes the order/data exchange with its outer coordinator nodes and sensor nodes.Applying the system, the man-machine interface is friendly and easy to understand.IV. CONCLUSIONThis paper puts forward a new design scheme of mine alarm system based on ZigBee technology. It carries out the self-organized wireless network of the mine safety parameter (mainly including the content of harmful gases, for example gas, temperature, humidity, and ventilation etc.) monitoringand alarming system. Although it is still in research, its various advantages have been shown: because the wireless correspondence system doesn’t pave the circuit used for the correspondence any longer, it is short-termed, small –invested, easy to upgrade and rebuild at the initial stage. Especially the emergence of wireless single chip microcomputer CC2430, the system on a chip ( SOC ) Loading the ZigBee technique which is of rich resources and powerful function, can vividly and conveniently form the system so as to adapt to different scales, different conditions and different requirements, and the system constructed is of low cost, low work consumption, high stability and low complexity; aiming at characteristics of the mines, it adopts the wireless communications mode to make the system be of clear hierarchies and convenient to manage. These advantages will make it have broad application prospects.REFERENCE[1] S. Liu, “Application Research of Radio Communication in Mine. alarmSystem,” COAL SCIENCE &ENG INEERING[CHINA] , no. 1, pp 110̚114, 2006[2] Callway E, “Home Networking with IEEE802.15.4:A Developments forLow-rate Wireless Persenal Area Networks,” IEEE Communication Magazine.2002, vol. 40,no. 8, pp 70̚77, 2002[3] Howitt I, “IEEE 802.15.4 Low rate Wireless Persenal Area NetworksCoexistence Issues,” Wireless Communications and Networking, no.3, pp 1481̚1486, 2003.[4] REN Li-ke, “Research and Application in Vehicle-Borne Diagnosis ofZigbee Technology,”Journal of Wuhan University of Technology(Management and the Information Engineering Edition) , vol.27.no.5,pp 85̚88, 2005.[5] Neelakanta,Perambur S,Harshad D.Robust, “Factory WirelessCommunications:A Performance Appraisal of the Bluetooth and the ZigBee Colocated on an Industrial Floor,”IEEE Computer Society 2003, no.3,pp 2381̚2386, 2003[6] ZAI Lei, “A Kind of New Network Communication TechniqueZigBee,” Microcontrollers & embedded System, no.1,pp 12̚14,2006 [7] H. Li , “Applied Interface Technology of MCS51 series monolithicprocessor,” Beihang university press. pp499̚505, 2002[8] P. Yu, “ZigBee-A Wireless Communication Protocol with Features of LowPower,Low Cost, High Reliability and Low Complexity,” Process Automation Instrumentation, vol. 26. no.5,pp1̚4, 2005[9] Trung-Kien Nguyen,Chung-Hwan Kim,Gook-Ju Ihm. “CMOS Low=noiseAmplifier Design Optimization Techniques,”. Microwave Theory and Techniques(IEEE Transactions), vol. 52. no.5,pp1433̚1442,2004[10] Y. Zhou , “ZigBee Wireless Communication Technology andInvestigation on Its Application,” Process Automation Instrumentationˈvol. 26. no.6,pp5̚9,2005[11] X. Liu, “Centralized Management and Control of dispersion equipmentBased on a Configuration Software,”Mechanical research & applicationˊV ol.17,no.1,2004。