The study on the Coal Mine Safety Integrated Monitoring and Early Warning System DesignUsing the S-MAC Protocol

Transcription

1 The study on the Coal Mine Safety Integrated Monitoring and Early Warning System DesignUsing the S-MAC Protocol School of Economics and Management, Hebei University of Science and Technology, Shijiazhuang Hebei , China Abstract Network monitoring system is handled by the automatic collection of web content, sensitive word filtering, intelligent clustering classification, topic detection, thematic focus, statistical analysis, a number of links to realize the need of the supervision and management of network public opinion, and ultimately the formation of public opinion, special reports, analysis reports, statistical reports, decision-making and management have complete control of public opinion, the dynamic, to make the right to guide public opinion, provide an analytical basis. The current monitoring system has some drawbacks such as small monitoring scope and less real-time. Coal mine safety monitoring and early warning systems are designed based on wireless sensor network in this paper. This system realized channel access to S - MAC protocol, and transmitted environment information collected such as CO, CH4, temperature, humidity and my roof pressure, etc. to the monitoring station and realized real-time monitoring of the mine working environment parameters. Modeling simulation is performed on the wireless network structure by applying OPNET software, and the results show that in the wireless transmission condition, 20 nodes sent 1000 data packets, more than fifty of which are received. Wireless transmission network performs well. Keywords: Wireless Sensor Network, Coal Mine Safety, S-Mac,Opnet,Monitoring System 1. Introduction China is a large country of coal production and use. 70% of the nation's electricity demands are solved by thermal powers which still rely on coal. However, due to backward technology, China has less open coal mines, which still mainly rely on mining by workers in deep underground [1]. Because of the complex environment, coal mine safety accidents often occur with heavy life and property loss during coal mining. Mine disasters result from many causes. Gas overrun has no timely process, mining super powers, China's coal production in general, universality, multiple characteristics. Such unsafe behavior was widely distributed throughout the production command. The front-line jobs, such as various types of links, are as well as coal mining and tunneling. In addition to mine collapse, there are a gas explosion and higher dust concentration. Therefore, in order to reduce accidents, ensure life and property safety of the workers. It is necessary to perform real-time detection of various parameters of down hole, such as the environment of CO, CH4, temperature, humidity dust and coal mine roof pressure [2]. The current coal mine safety monitoring and early warning system of coal mine enterprises mostly adopt cable transmission mode to transfer information about down holes environment. With mine workers continuous mining, working environment is changing, and underground tunnel space is expanding. Compared with wireless transmission, cable transmission is prominent in agility and scalability [3]. Coal mine safety testing and early warning system of cable transmission mode has certain use limitations [4], and can t meet the increasingly strict down holes safety standard. Currently, line cable detection system has many problems, such as: a long time, cable corroded, or due to underground work and other reasons, the cable, once broken, will render the system unusable. Therefore, there is an urgent need to upgrade and update the existing coal mine safety monitoring system. To sum up, in view of the current cable monitoring system problems, a wireless sensor network is set up based on coal mine safety monitoring and early warning system to protect coal mine workers and enterprise property life and safety, and ensure the smooth implementation of production, so it has very important significance and value. The establishment of the new monitoring and warning system can not only perform real-time monitoring of coal mine environment information but it can help us determine the location of the accident site, and provide strong support for evacuation and rescue work. Journal of Convergence Information Technology(JCIT) Volume8, Number6,Mar 2013 doi: /jcit.vol8.issue6.21

2 2. General structure of monitoring system The general structure of the monitoring system is mainly composed of four parts, namely, the monitoring center, transmission network, data acquisition unit and equipment terminal [5]. As is shown in Figure 1, it can be seen that the system consists of two parts: down holes information collection system and ground monitoring center. Sensor node of down holes monitoring system is responsible for collecting the environmental information. According to certain communication protocol, radio frequency module is transmitted in wireless sensor network. The information collected can be transmitted real-time to the gathering node through AD hoc network. Transmission interface is installed between convergence nodes of server on the ground and wireless sensor network, and address data and information data of coal mine environment information got from convergence nodes are transmitted to upper server through the cable transmission. The server processes information data collected and then sends them to the ground monitoring center [6]. The ground monitoring center is mainly responsible for the analysis and storage of the data collected. It can timely track environment changes in various areas of mine and roadway through the analysis results. When there are emergencies, the monitoring center can rapidly respond, send signal alarm to the dangerous area, and accurately locate dangerous cite according to the feedback information of sensor nodes. This realizes the real-time monitoring and early warning of the down holes environment [7]. Figure 1. Coal mine wireless integrated monitoring and warning system structure diagram 3. Information collection/transmission network design This paper adopts Tiny OS operating system, specially designed for wireless sensor network, to complete sensor node data transmission function [8]. Tiny OS operating system can play out the characteristics of the hardware structure, reduce the node power consumption, and improve sensor network performance and development efficiency. 3.1.Wireless network structure design In wireless network, sensor node is fixed in roadway at certain intervals. In monitoring environment, when monitoring parameter is over proof, monitoring point can raise the alarm. In order to determine the location of the accident, each fixed node s address information is recorded as a fixed coordinate point in computer database. In order to facilitate receiving the information data sent out by wireless sensor network node, gathering nodes are installed in the main roadway. The information data collected by each sensor node through wireless way are summarized, and transmitted to information collection server through wire transmission. The sensor nodes in wireless sensor network structure and network structure, respectively described in figure 2 and figure 3.

3 Figure2. Wireless sensor network structure 3.2.Communication protocol design Figure3. Sensor node structure S - MAC channel access agreement is adopted in communication protocol. S - MAC is put forward based on IEEE competition and control protocol, which belongs to the distributed MAC protocol [9]. The advantage of S - MAC is that when processing data transmission in wireless sensor network, energy consumption can be reduced, and not any local or global main node needs to be dispatched. It can reasonably arrange channel occupancy time by sensor nodes detection of adjacent other nodes. S- MAC protocol adopts following mechanisms in too much energy consumed in wireless sensor network: (1) In a cycle, let interception and sleep have certain low duty ratio. This can make nodes priority in a sleep state when two states: interception and sleep are optional. In this way node energy consumption is reduced; (2) Use request receiving/sending signal mechanism. Network nodes will monitor carrier before sending data. After the failure of competition channel, the competition nodes will enter sleep state and send data again when the channel is free; (3) Effective virtual cluster is formed with neighboring nodes through sleep scheduling mechanism, which reduces nodes free interception time. Local synchronous mechanism is applied to ensure that neighbor nodes realize synchronous in a single jump, and avoid the occurrence of collision and crosstalk. LEACH protocol is applied to routing agreement. LEACH is an energy efficient routing protocol, which optimizes the energy of data transmission, improves the network life time, and is suitable for the energy efficiency requirements in mine work. And, the agreement also adopts multipath routing mechanism to improve reliability.

4 3.3.Wireless sensor node design The design of wireless sensor network nodes is composed of four parts, for: sensor module, processor module, communication module and power supply module. Structure is shown in Figure 4. Node development board is TSZ-008 development board, and the communication interface adopts standard RS-232 serial port to connect computers. 3.4.The processor module Figure4. Node hardware structure design The processor module is the core of whole node data processing and control. The system chooses PIC16F877A single chip microcomputer of MicroChip. SCM is "Harvard" structure. Instructions and data reading can be conducted at the same time, which effectively improves single chip performance. And PIC16F877A also has advantages like less pin, high stability, powerful, A/D conversion, I/O functions, and repeating burning program [10]. 3.5.Wireless transceiver module Wireless communication module is responsible for data communications between sensor nodes. This paper chooses CC2420 radio frequency transceiver of Chipcon Company, featuring nodes channel, which can expand as needed. In addition, the chip also has characteristics as low power consumption, fast transmission speed, and short wake up time. 3.6.Power supply module Power supply module is nodes power source, the main function of which is to ensure the power supply for the nodes and normal operation of the nodes. Because sensor node working environment is bad and wireless communication mode is adopted, so power supply used in cable power supply can t be adopted for wireless sensor network nodes. The general present method is the use of portable power and battery as a power supply. At present, most coal mines use battery. 3.7.Wireless sensor module Wireless sensor module is the module directly contacts external environmental information. It is responsible for the induction of field information. To mine s special environment, mine roof pressure, gas concentration, the temperature and humidity of air and dust and other environmental information need to be collected. The design adopts the following main sensors: broad spectrum gas sensors, humidity sensors and mining top pressure sensor. (1) Broad spectrum gas sensors: Shenzhen David lai products, which is the advanced gas sensor of mature heater structure semiconductor gas sensor in application. Sensitive matrix is SnO2 materials. Its production technology is mature and mainly used in natural gas, coal gas, and liquefied petroleum gas (LPG), smoke, hydrogen, alcohol and leak detection, monitoring, alarm device and sensing element in intelligent detection. It has high sensitivity. (2)Temperature/humidity sensor: humidity sensor used PCMini52 sensor of MICHELL company, which has microprocessor control and more check. This makes the outstanding performance in precision and linearity of PCMini52 temperature and humidity transmitter. The mini probe provides two routes analog output, which either can be temperature, relative humidity, dew point or absolute humidity signal. It can be widely used in temperature and humidity detection of complex environment.

5 (3) Mining top pressure sensor: mine roof pressure parameters uses GD-307 mining top pressure sensor. This product is a special instrument in monitoring mine working roof pressure change, which can automatically transfer top fender s sink into electrical signal into a relevant equipment. Input voltage is dc 9V~18V, a range of 1~10 Mpa, 2%basic error, 1MA~5MA output signal, and effective transmission distance is 1500 m. SCM receives voltage signals, therefore, it is necessary to convert 1MA~5MA sensor output current signals to the corresponding voltage signals. Here set ADC voltage reference to 3.6 V. It is required to convert them to 0 ~ 3.6 V voltage signals. The conversion circuit is shown in Figure Network node design Figure5. Current voltage switching circuit Wireless network node is composed of acquisition and receiving. When nodes begin performing information acquisition, first initialize settings, then enters the preparation stage; when an information collection cycle is completed, a request is sent to the system. After getting an answer, start sending data, and return after it. Initialization process is the pretreatment of SAM; after collected by sensors, the information is transmitted in form of data packets, and then sending to the communication module to proceed RF output. The receiving application is mainly to complete data receiving and processing. Information acquisition and receiving software process respectively is shown in Figure 6 and Figure 7. Figure6. Node information collection work flowchart

6 4. Simulation analysis Figure7. Node information work flow chart The mine's environment is very complicated. With the extension of mining, roadway becomes longer and narrower. In order to guarantee the environmental information collected by wireless sensor network nodes could be accurately sent to the gateway equipment. Model simulation is needed to MAC protocol. Here OPNET is used as communication network simulation software [11~12]. OPNET provides reliable quantitative basis for network planning and design. The advantage is that the existing network model is able to be quickly set up, easily modified and simulated. In order to reduce the difficulty of the modeling, this paper applies the modified model of local area network (LAN) agreement. Modeling simulation process is shown in Figure8. Figure8. OPNET simulation modeling flowchart

7 The basic conditions for simulation are: there are 20 nodes in wireless network, ten different packets, and the setting of packet arrival time interval. The condition of the simulation is: the quantity of sending packets of all nodes is 103. Last analyze the received packets quantity. Simulation result is shown in Figure 9. Figure9. Receives packets quantity curve From the analysis of Figure 9, although twenty nodes have sent 1000 packets, the receiver gets more than fifty packets. It is acceptable in the simulation conditions in wireless conditions. This means that the established simulation model can reflect the characteristics of the prototype machine more effectively. 5. Conclusion According to the existing problems and the insufficiency of coal mine safety monitoring system, coal mine comprehensive safety monitoring and early warning system is designed based on wireless sensor network. This paper introduces the comprehensive monitoring system works, designs the hardware of wireless sensor nodes, and gives software flow chart of information collection and receiving. Mine environment information real-time monitoring is achieved through wireless sensor network. Finally, through the OPNET software modeling simulation, wireless packet acceptance rate achieves the anticipated results in wireless condition. 6. References [1] Tang Hongwei, Sun Caixia, Wang Xiaoping, "CL-TDMA: A Cross-Layer TDMA-Based MAC Protocol for Event Driven Wireless Sensor Networks1", JCIT, Vol. 7, No. 12, pp. 85 ~ 93, 2012 [2] Li Yuanyuan, "Energy Efficient MAC Algorithm based on Collision Avoidance for Wireless Sensor Networks", AISS, Vol. 4, No. 21, pp. 31 ~ 39, 2012 [3] Lujuan Ma, Henry Leung, Deshi Li, "Hybrid DCSK/TDMA Multi-Rate MAC Protocol for Underwater Acoustic Sensor Networks", JDCTA, Vol. 6, No. 19, pp. 565 ~ 572, 2012 [4] Chen Chen, Xinbo Gao, Qingqi Pei, "A Delay Guaranteed and Services Differentiated MAC Protocol Based on Location and Reservation in Near-Space", JCIT, Vol. 6, No. 2, pp. 120 ~ 130, 2011 [5] Shuqiao Zhou, Yong He, Yanyong Zhang, Ruixi Yuan, "Towards High-performance Dedicated Control Channel in Multi-radio Multi-channel Networks", JCIT, Vol. 6, No. 6, pp. 7 ~ ~ 18, 2011 [6] Shuqiao Zhou, Peter Dely, Ruixi Yuan, Andreas Kassler, "Mitigating Control Channel Saturation in the Dynamic Channel Assignment Protocol", JCIT, Vol. 6, No. 6, pp. 271 ~ 281, 2011 [7] corresponding author Qi Yang, Yuxiang Zhuang, Jianghong Shi, "An Evolutionary MAC Protocol based on FPRP for Decreasing Delay", JDCTA, Vol. 4, No. 9, pp. 194 ~ 200, 2010 [8] Dileep Kumar, Saleem Ahmed, Yeonseung Ryu, "Quality of Service (QoS) of Voice over MAC Protocol using NS-2", JCIT, Vol. 3, No. 4, pp. 76 ~ 83, 2008 [9] Ren Gao, Hui Wang, "A Novel Multi-channel MAC Protocol for Distributed Cognitive Radio Networks", AISS, Vol. 3, No. 11, pp. 132 ~ 139, 2011

8 [10] Xin Feng, a, Hua-min Yang, b, Hong-bin Wang,, c, "A Study of MAC Protocols for WBANs Based on Markov Chain", IJACT, Vol. 4, No. 6, pp. 100 ~ 108, 2012 [11] Zhou Qi, "Wireless Network Performance Simulation of Error-correcting", AISS, Vol. 4, No. 9, pp. 58 ~ 66, 2012 [12] Li Yuanyuan, "Energy Efficient MAC Algorithm based on Collision Avoidance for Wireless Sensor Networks", AISS, Vol. 4, No. 21, pp. 31 ~ 39, 2012