Proceedings of the 2009 13th International Conference on Computer Supported Cooperative Work in Design
Development of a Real-time Mine Auxiliary Monitoring System Using RF Wireless Sensor Networks Lin-Song Weng1, Ching-Lung Lin2, and Hsueh-Hsien Chang 3 Dept. of Electronic Engineering, Ming Hsin University of Science and Technology, Hsinchu, Taiwan.
[email protected] 2 Dept. of Electrical Engineering, Ming Hsin University of Science and Technology, Hsinchu, Taiwan.
[email protected] 3 Dept. of Electronic Engineering, Jin Wen University of Science and Technology, Taipei, Taiwan.
[email protected] 1
Abstract The mining techniques are based on the computer supported cooperative work using a real-time minemonitoring system. Without this system associated RF wireless network, the safety, and security of mineworkers cannot be understood and ascertained. This paper proposes a mine auxiliary sensor system (MASS) will effectively monitor all situations in mine especially for the safety of mineworkers. The implementation results indicated that real-time mine auxiliary monitoring system (RMAMS) standard is adopted for a real-time mine-monitoring system. D-ASK and D-FSK can satisfy requirements for different environment more than other communication protocol. Keywords: Mineworker, RF wireless network, Minemonitoring system, Gas sensor
signal from RF channel. The emergency signal will be spread by system main control computer (SMCC) program. Recently, several papers have proposed wireless sensor networks to study energy efficient and data compression. MASS has an intelligence active sensor and repeater. When CPU receives the emergency signal from the sensor of MASS, it will make a decision to decide the procedure of processing. There is a system control interface unit (SCIU) for every branch of mine. The emergency signal will send to SCIU when the MASS near this SCIU receives the emergency signal. This emergency signal will send to SMCC from SCIU by RF internetwork. The SMCC will send the gas leakage information to every SCIU. The SCIU also transfer this information to every MASS for the branch of this SCIU. The information includes where the area is dangerous and what is the direction of escape for the mineworkers. The information is decided by SMCC.
1. Introduction Early days, mineworker carries an animal like a bird with him while he comes into the mine. The mineworker will clearly understand the situation of mine, ex. gas leakage by means of the sense of smell from animal. Now, mineworker is asked to carry a gas sensor with himself while he comes into the mine. The detection of gas is very important for mineworker while he comes into the mine. The gas sensor is installed in the mine everywhere to construct a real time minemonitoring system by using a reliable RF wireless network [1]. Figure 1 shows a mine auxiliary monitor system. In this system, a mine auxiliary sensor system (MASS) includes a single chip for CPU, gas sensor, RF transceiver IC, rechargeable battery, AC to DC converter, LED, speaker and mercury switch. This MASS will send an emergency signal to the next neighbor of MASS using RF transceiver when it detects any gas leakage until all MASS receive the emergence
Figure 1. Configuration 1 of Real-time Mine Auxiliary Monitor System.
978-1-4244-3535-7/09/$25.00 ©2009 IEEE
680
Besides active sensor function of MASS, MASS also has an intelligent repeater function. The ID code is used to identify data forward direction for all RF wireless networks. To decrease dangerous event, the next one MASS will continue automatically to forward the emergence signal if the MASS has no response when it receives the RF emergency signal over 3 times from network. SCIU is an interface unit between MASS and SMCC. In general, SCIU offers a RF transceiver channel to link with every MASS for the branch of mine. SCIU can receive the instructions from SMCC and forward information to MASS. The SCIU can also receive a phone call instruction from SMCC to call out the mine manager and/or police officer. The mine manager and police officer can immediately send an emergency instruction by telephone or internet to all mineworkers. All procedures are processed by a DTMF signal inside SCIU [2]. The DTMF signal can translate the remote phone code to SMCC. Figure 2 shows another type of real-time mine auxiliary monitor system. SCIU can be looked as a smart MASS RF repeater for internal node, this node uses former MASS instruction and starts branch communication channel. SMCC is a system main control computer. All communication protocols of MASS [3] are programmed by the SMCC. Mine manager make a decision from the emergency processing support software of SMCC. The decision support message is sent by SMCC computer using internet or telephone voice.
[4] can satisfy requirements for different environment more than other wireless communication protocol. This paper is organized as follows. The hardware structure of RMAMS is addressed and described in Section 2. The software structure of RMAMS is described in Section 3. Experiment results are described in Section 4, which includes a number of benchmark comparisons of the various communication protocol standards; for examples, Bluetooth, ZigBee, Wi-Fi, UWB, D-ASK and D-FSK in band, speed, distance, capacity, consumption, cost and application. The conclusions and further work are stated in Section 5.
2. The hardware structure of RMAMS A Real-time mine auxiliary monitor system includes MASS, SCIU and SMCC. MASS is installed in the mine. MASS has an active sensor for water check, gas leakage, rock collapse and pressure change. The CPU of MASS can read over two signals for different sensor in the same time. The CPU can also read over three MASS input data to compare with each other, and then send a dangerous identification in a small local network. The emergency signal will be sent to SMCC by this CPU of MASS. Figure 3 shows the hardware structure of MASS. The CPU of MASS connect with some different hardware devices which include RF transmitter and receiver circuit, flash memory, sensor interface circuit, voice driver circuit and LED. The flash memory [5] can read MASS ID to recognize user. The voice driver circuit has an amplifier to amplify signal to speaker. The LED is used to display the situation of AC power and the energy of rechargeable battery.
Figure 2. Configuration 2 of Real-time Mine Auxiliary Monitor System. In this paper, a mine auxiliary sensor system will effectively monitor all conditions in mine especially for the safety of mineworkers is proposed. The experiment results indicated that real-time mine auxiliary monitoring system (RMAMS) standard is adopted for a real-time mine-monitoring system. D-ASK and D-FSK
Figure 3. The block diagram of MASS. A rock collapse sensor always settles in anywhere for the rock easier collapse place. The system of the
681
rock collapse sensor is organized by a microphone, analog to digital convertor circuit (ADC) [6], microcomputer, and RF transceiver. Microphone is used to collect the sound of rock collapses. ADC circuit is used to convert an analog signal to digital signal that is a pulse code modulation signal (PCM) for sound. Microcomputer is used to run a digital signal processing (DSP) software [7] and digital speech processing technology software [8] to identify the sound signal of rock collapse. A rock collapse MASS builds in MASS. Water leaking sensor is constructed by a plastic hardware structure and a mechanical structure. There are many tubes are used for testing the water levels in the mine. Figure 4 shows a plastic ball inside all tubes. All of the balls in the tube are linked with soft string and the soft string is linked with a rod switch. The rod switch is made by two contactors. The water level will be checked by MASS when the exudation of water in the mine. The plastic ball will lift up when the water is higher than the water level. The two contactors will be switched on, when MASS receives different signal for checking the water level, a MASS test signal will send back to SCIU and SMCC.
Figure 5. Two small area sensor networks RMAMS. SCIU is a RF interface channel between SMCC and MASS. Figure 6 shows the hardware structure of SCIU. The SCIU includes RF transmitter and receiver, RS232C interface circuit, two flash memories, LCD, voice IC, and telephone interface circuit. The RF transmitter and receiver are used to link MASS. RS-232C interface circuit is used to link SMCC. One flash memory is used to record RF ID of MASS. LCD is used to display all situations, control functions, and input data. Voice IC is used to record the instructions of different emergency from user. Another flash memory is used to record the telephone number of mine manager and 911. Telephone interface circuit is used to depend on the instruction of CPU to dial the phone number of the mine manager or police officer.
Figure 4. A water sensor checking MASS. There is water leaking area or rock collapse area somewhere in the mine. Figure 5 shows two small area sensor networks. In these small area sensor networks, there is a master MASS and others are slaving MASS. Master MASS cannot only receive the signals from main system but also regenerate the signals to the next MASS. The major work of small area sensor network is that send polling signal to all slave MASS and receive the echo signals by sequence from the slaves. After master MASS has received all signals from slave MASS, it send a conformation to decide which slave MASS has an emergency signal. When MASS receives a system test signal, it will generate again a new data signal and feed back to SCIU and SMCC one by one at this moment.
Figure 6. The block diagram of SCIU. A System Equipments Setting Machine (SESM) can be used to set the ID code of MASS and SCIU. Figure 7 shows the hardware structure of SESM. In this figure, the SESM includes RF transmitter and receiver module, flash memory, LCD and buzzer. The RF transmitter and receiver module are used to set ID number of MASS. The flash memory is used to record the used number of MASS. LCD is used to display ID code and operation function. Buzzer is used to send an echo of bi-direction ID code. Some function tests of MASS can be operated
682
in the SESM. The function tests include sensor function test, RF transmission and receive function test, LCD test, SCIU telephone test and speaker voice report test.
Figure 8. Data communication format. Figure7. The block diagram of SESM.
3. The software structure of RMAMS Compatible software and RF communication protocol of RMAMS have been developed. Some physical signals ex. gas, water, pressure, etc. are recognized by the software of artificial intelligent in the MASS. The emergency signal is checked and transferred between MASS, SCIU, and SMCC by RF communication software. The rules of the communication protocol are defined as below: 1) Data communication speed: RF data communication rate uses 3Kbps for main mine tunnel. RF data communication rate uses 3K bps for sub-mine tunnel. 2) Data communication protocol: RF data signal communication protocol depends on different hardware structure. Figure 8 shows data format for data communication. There are three types for data format. They are as below: a) Emergency data format: The format is generated by MASS when the sensor of MASS detects the emergency signals. The emergency data format shows in figure 8. b) RF Test Data Format: RF test data is generated by SMCC. There are 88 bits for one string. A block data is ten data strings. SMCC send two blocks for one segment data. This segment data has two modes for test mode as type 1 data and test echo mode as type 2. When SMCC send the test mode data, MASS feeds back a data for test echo mode. These two modes have same length and transmission speed but they are not same delay time so they will not interference. All MASS will receive these test data by SCIU. The MASS will feed back automatically after MASS receives some error situation like as a little water in the den or a little rock signal to SMCC if one of the MASS does not work. c) RF Test Echo Data Format: The data format is same with the emergency data and test data, but it uses different delay time to transfer data signals.
The main test program is executed by SMCC. The programs will automatically check the condition of MASS ex. RF communication, work situation for all sensors, auxiliary battery, SCIU etc. because the work condition of electronic devices is very bad in the mine. Figure 9 shows the flowchart of System Main Program (SMP). The SMP will check the hardware and communication channel in the initial setup. This system will setup system test function and send a test signal to system. After system send a test function, SMCC will receive a test echo signal and any emergency signal from MASS. SMCC generates a test signal for system. This signal will automatically test MASS by user. After system sends a test program, all MASS will feed back an echo data. This echo data includes MASS communication port error, MASS group response of mine situation, some other condition of MASS like as battery out of date, etc. The test for all MASS will finish after the SMP has checked all the work situation of MASS. In general, one Mass is working normally, the SMP will generate a new test signal to test next one, and it will not give any echo signal. Nevertheless, MASS has some problems, the small group of local network will receives some test data. The system will automatically generate a new echo test data and feed back to system. MASS will generate again a new test signal and forward to next Mass. When SMP feed back an error echo signal to preceding MASS, the preceding MASS will transmit an echo data back to SCIU and then SMCC. Figure 10 shows a flow chart of MASS. In this diagram, the CPU will detect the real situation of MASS to control the power of RF transmitter. The MASS will generate a new test signal to next one if all condition of the MASS works normally. The MASS cannot receive the echo test signal from the next one if the communication channel of next one has any problems. The MASS will ask RF transmitter to enhance the power of signal and regenerate a new test signal for next two MASS. The next two MASS will also feed back a test signal to the MASS.
683
Figure 10. The flowchart of MASS.
Figure 9. The flowchart of SMP. Not all devices that can cause spark are allowed to use in mine. Some electronic devices like as sensor uses relay or switch are forbidden. The optical sensor is adopted for detecting the physical signal in the mine. An analog to digital converter (ADC) circuit can convert the analog physical signal to digital electrical signal. The CPU of MASS can accept the digital signal to make a decision for the mineworkers in the mine. Figure 11 shows the RF data format of transmission signal. The data format includes test signal data format and emergency signal data format. Both of data format have the same transmission data speed. Ten data strings organize one data block. Type A and type B have the same data strings and time of space. When data has been sent, the system will make two block data strings as one frame. Forward data string frame has two block data. Each data of block delay 100 ms. The backward echo data frame has two block and the data delay 3 ms. When these two type data radiate at same time, it will never inference for each other. Moreover, these two type data strings can receive simultaneously between MASS, or MASS and SCIU.
Figure 11. Data format of forward data string and backward data string.
4. Experiments and results In this paper, a number of benchmark comparisons of the various communication protocol standards; for examples, Bluetooth, ZigBee, Wi-Fi, D-ASK and DFSK in band, speed, distance, capacity, consumption, cost and application are implemented. The result reveals RMAMS is good standard for a real-time mine monitoring system, especially for data transmission from SMCC on time to MASS, or from MASS to
684
SMCC, To increase the reliability of the communication channel, a communication test signal will always runs in the communication channel. When the system has any problems for some special case, e.g. rock collapse, gas leak, the system will check it in real time and make a decision to identify if it is necessary to call emergency or not. Table 1 shows the characteristic comparison for RF communication protocol standards, Bluetooth, ZigBee, Wi-Fi, D-ASK and D-FSK respectively. The ZigBee, D-ASK, and D-PSK should be satisfied for the requirements of the capacity of communication channel, but the cost and a volume, static power consumption have limited the hardware design for short data string communication protocol. In the mine Auxiliary Monitoring System, power consumption, system realtime monitoring is very important, RMAMS D-FSK communication standard always have long distance than RMAMS D-ASK, but it is necessary to spend more power and cost than D-ASK. Therefore, RMAMS DASK will be adopted in the system. Table 1 Characteristic comparison for communication protocol standards Standard
RF band (GHZ) Speed (Mbps) Distance (M) Link
Bluetooth IEEE 802.15. 1x 2.4
ZigBee
Wi-Fi
D-ASK
D-FSK
IEEE 802.15. 11b、g 2.4
RMAMS
RMAMS
0.43392, 0.868
0.43392, 0.868
54
0.038
0.5
0~100
100
200
P-P/star
P-P/star
65536* 65536 3mA
65536* 65536 30mA
100
IEEE 802.15. 4 0.868, 0.915, 2.45 0.02, 0.04, 0.25 75
(100mW)
(2.4GHz)
P-P/star
P-P/star
ISP
Ad-hoc
(Hot Spot)
1~3
Capacity
8
Star cluster 65536
Consum.
1~100
0.5~1
1~100
Low cost
Low cost
High speed Hot spot
Short distance Low cost
(mW) Character
RF
32
Application
Voice
Wireless Sensor
Internet
RMAMS
Short distance High speed RMAMS
Cost
Low cost
Low cost
N.A.
Low cost
Low cost
(Ad-hoc)
off. A small group MASS with local area network communication method develops an identification method that can make system precisely identify where the emergency has. MASS identifies rock collapse in mine using DSP method to identify the emergency [9]. The MASS also adopts for checking water leaking. In the future, the RMAMS can extensively use in the mine for safety of the mineworkers. Rock collapse can be detected by sound from DSP techniques. Low power consumption and low cost for communication IC are necessary to develop gradually.
References [1] R. O. Cunha, A. P. Silva, A. A. Loreiro, and L. Ruiz, "Simulating Large Wireless Sensor Networks Using Cellular Automata," Proc. 2005 IEEE the 38th Annual Simulation Symposium, 2005. [2] R. L. Freeman, "Telecommunication System Engineering," Third Edition, Wiley Publication, pp.159162, 2005. [3] D. E. Comer, "Internetworking with TCP/IP Principles, Protocols and Architecture," Fifth Edition, Pearson Prentice Hall, Pearson Education Inc., Volume 1, 2006. [4] B. Sklar, "Digital Communications, Fundamentals and Applications," Prentice-Hall, Inc., pp.248-206, 2001. [5] N. Alexandridis, "Design of Microprocessor-Based Systems," Printice-Hall Inc., pp.129, 1995. [6] B.P.Lathi, "Modern Digital and Analog Communication Systems," Third Edition, Oxford University Press., New York Oxford, pp.5-265, 1995, [7] L R. rabiner, R. W. Schafer, "Digital Processing of Speech Signals," Printice-Hall Inc. Englewood Cliffs, New Jersey 07632,1978. [8] S. Furui, "Digital Speech processing, Synthesis, and Recognition," Marcel Dekker, Inc., New York and Basel, 1989. [9] S. Russell, P. Norving, "Artificial Intelligence a Modern Approach," Second Edition, Pearson Prentice Hall, Pearson Education Inc., 2003.
5. Conclusions The safety of mineworkers is very important for their family and government. In this paper, a RF wireless sensor network and theirs communication method is proposed. A real-time mine auxiliary monitor system with RF wireless sensor network has been proposed to satisfy the requirements of the capacity of communication channel. An independent MASS with battery supports the communication system when power
685
