The Remote Monitoring System Based on GPRS for the Health State of

The Remote Monitoring System Based on GPRS for the Health State of Civil Engineering 1 Gang Li, 2 XiLong Che *1, First Author and Corresponding Author School of Information Engineering,Chang an University, Xi an 710064,China, Email: gangli321@126.com 2, Second author School of Information Engineering,Chang an University Xi an,710064,china Abstract Civil engineering health monitoring is a major part of the project construction. As a basic guarantee of engineering operations, it provides evidence and guidance for project maintenance, management and post-project construction. The designed far-distance civil engineering health monitoring system consists of the front-end collection module, backstage control panel and the inbetween communication system. Comparatively speaking, this method overcomes the weaknesses of the traditional data-collection method of on-the-spot data collection by technicians personally, such as low-efficiency, time-consuming and the complex of data processing. The system separated the fardistance data collection and backstage data analysis and processing, saving considerable human resources and funds, reaching the real-time engineering health monitoring in the real sense. The designing concept of module enables the system portability. The low usage charge reduces the monitoring cost. The system has proved to be real-time and highly reliable after several months application. Keywords: remote monitoring,gprs(general Packet Radio Service),modularization 1. Introduction It is very important to monitor the health state of civil engineering after the completed construction of the civil engineering, and it can provide practical basis and guidance for engineering repair, maintenance, management and subsequent engineering construction. It is a basic guarantee for the engineering operation [1-2]. The traditional collection style is manual field collection. After the engineering is completed, the technical operator should go to the measurement field and collect data in each sensor one by one, the sensors are embedded into the different parts of the engineering to monitor the various properties, these data should be transmitted to the PC and processed. The style of manual field collection has inherent disadvantage, such as higher cost, lower efficiency, time consuming, and tedious data process. The embedded position of some sensors may not satisfy the design requirements. Thousands of embedded sensors need to be monitored in engineering. The collection process is time consuming. It can not feed back the real-time engineering monitor quantity, and can not completely play the role of a monitor. The traditional style of collection consumes lots of human and material resources [11]. In this paper a method of remote monitoring the health state of civil engineering based on GPRS is presented. The style of wireless transmission is adopted for the purpose of remote monitor. As the remote data collection, background data analysis and management are separated, it can reduce the cost of human resources greatly, and realize the real-time collection. Meanwhile, the less cost of the GPRS is a unique advantage compared with other collection styles. The use of GPRS can reduce the monitor cost largely, and powerfully guarantee the engineering operation [3][12]. 2. System profile The GPRS concept is a set of wireless transmit style developed on the base of packet switched concept. It is one kind of mobile data services used by GSM mobile phone subscriber, that is to say, International Journal of Digital Content Technology and its Applications(JDCTA) Volume6,Number8,May 2012 doi:10.4156/jdcta.vol6.issue8.4 26

GPRS is continuation from GSM. GPRS is different from previous continuous transmission on channel style. It is transmitted by the style of seal packet, so the fee paid by the user is calculated by transmitted data, and the whole channel isn t fully used. It is cheaper in theory. The transmission rate could be increased to 56 Kbps, and the maximum value is up to 171.2 Kbps[5] [8]. The system is designed on the idea of modularization design, and the remote data collection function is separated from background data analysis and management. The core of the remote data collection module is embedded MCU. The data transmission channel is based on the GPRS module. It receives the background instructions, processes data, and sends the data back to the background. In addition, it can solve the problems quickly, change rapidly, and increase the operation efficiency of trouble debugging. The background module receives the data from remote data collection module through GPRS module, and analyzes data, manages data or sends measure instructions by the host computer software. The whole system provides theoretical guide for the engineering operation. The whole system structural diagram is shown in figure 1 [6][14]. The function of remote data collection module is to receive data from various types of sensors, which are embedded into the different parts of the engineering component. Sensors connect to the splitter (a type of auto connection apparatus) by wire. The splitter has reserved interface, which is connected to the embedded MCU. When the MCU sends instructions, the splitter gives corresponding actions, and feeds back the measured signal to MCU. The embedded MCU connects to the GPRS module at the same time. After the measurement has been completed, the data are sent back to background through the GSM network[7][10]. The obvious advantage is that GPRS is always online, which is very convenient to general users. The host computer does not necessarily run all the time. When it needs to achieve the engineering state, the software of the host computer will run, and GPRS can establish connection automatically. The software of the host computer receives the measured data, and makes simple data analysis and data management. Meanwhile, the software of the host computer has reserved data access interface for other software, so as to make further disposal conveniently [13]. Figure 1. System Structure Diagram The typical structure is shown in figure 1, There are various forms in practice. The main difference of the various forms is that the remote data collection module doesn't send back the data by the GPRS module immediately. On the other hand, it sends the data to the remote data collection module in the figure 1 through wireless module or RS485 bus. The master MCU, as shown in figure 1, needs to add wireless or RS485 bus interface. Theses two forms are both used in actual operation. The wireless data transmit module and RS485 data bus are used to accomplish data relay. The purpose is to deal with the situation of no GPRS signal or unstable signal. One background can manage several remote data collection modules so as to realize the purpose of centralized management[4] [9]. 27

3. Hardware selection The remote data collection module is composed of 8-bit MCU, signal amplifier and filter, data communication interface, power module etc. The principle structural diagram of the remote collection module is shown in figure 2. Figure 2. The Principle Structural Diagram of The Remote Collection Module 3.1. 8-Bit master MCU The Master MCU adopts an 8-bit high performance single - chip microcomputer- P89V51RD2. P89V51RD2 is a kind of 80C51 microcontroller with 64KB program Flash and 1024B data RAM, the key characteristic of the Master MCU is the X2 style. The design engineer can make the processor operate with traditional 80C51 12 clock style or select the X2 style. At the same clock frequency, the X2 style can achieve twice handling capacity than the traditional one. It has programmable watchdog timer at the same time, so it can improve the reliability of the system. 3.2. GPRS module GPRS module adopts the ART-GPRS1090A wireless transmission module. It supports GSM/GPRS, embeds integral TCP/IP protocols stack, provides RS232/485 communication interface,and supports data communication model, such as: multiple data center,ptp(point to point),ptmp(point to multiple point),ctmp(center to multiple point) etc. The data terminal supports three operation styles: always on line, free down line and idle power. It utilizes multiple software and hardware reliability design, watchdog technology. The system uses the transmission style of point to point, which does not care about how the data is transmitted in detail, and the tedious server configure can be saved. The system development speed is improved greatly. The system uses its given RS232 interface, and connects the master MCU. The communication adopts the style of peer data transmission. 3.3. EEPROM storage The EEPROM adopts AT24C64, which has IIC interface. It has 64K-bit high speed CMOS serial storage. Each bit can be erased for 100 0000 times, and the storage data can be saved reliably for 100 years. It is used by the system as a temporary space to save the collected sensor data. After collecting all the sensor data connected to a splitter, these data will be read from EEPROM. As the sensor data are too large to be transmitted in one time, it is necessary to transmit several times. The data are sent to background computer according to the protocol, and it can be analyzed and managed by the host computer. 3.4. Signal conditioning The amplifier and filter circuit can debug the weak sensor signal to the master MCU disposal signal, and its core component is integrated operational amplifier LM324. LM324 has several merits, such as: internal frequency compensation, higher voltage gain, wide frequency band, wide power supply range, moderate price etc. It can satisfy the system requirements. 28

3.5. Splitter The decode circuit is composed of CD4514 chip and relay. It makes the splitter have the function of automotive connect sensors, and completes time-sharing acquisition of several sensor data. The splitter can connect 16 sensors when it has one CD1514. When parallel connection to several CD1514 is used, the connection number of the splitter can be increased. The components used in the system are industrial devices, so it could guarantee the remote data collection module can work stably for a long time. The splitter used in the system has been validated in practice, and it has higher reliability. 4. System software The system software is composed of two parts. One is remote data collection module program. the other is background host computer program. Remote data collection module program and background host computer must comply with user-defined protocol. The concept of the user-defined protocol is that communication object must comply with the rules together. After the protocol is established, both sides of the communication can understand the meaning of accepting or sending data package. 4.1. Remote data collection module program The master MCU is the core component and executes the program which is running in the remote data collection module. This program is based on the Keil development environment, and programmed with C language. The main function is to analyze data content, resolve instructions, execute action and collect sensor data. After the master MCU executes the program, it will monitor whether data arrive or not. When the data have been received, the master MCU analyzes the meaning of the data, and then gives corresponding operation. If no data arrive, the master MCU continues monitoring. After measuring all the sensor data connected to a splitter, the master MCU sends these data back to the background computer according to the predefined protocol. The master MCU execution flow is shown in figure 3. Figure 3. Main Control MCU Execution Flow 29

4.2. Background host computer program The software of background host computer is based on the VB development environment. It is constituted by three function modules: account management, site management and data management. The detailed function module structural relationship of this system is shown in figure 4. Figure 4. System Function Module 4.2.1. Account management The function of account management is necessary on general software. Background host computer software needs to be logged in and then used, in order to prevent the information leakage. The administrator can add account or delete account after his login. 4.2.2. Site management As one of useful functions, the site management has very important meaning. Background management, which is the core of the remote monitor system, needs only one. The actual engineering monitoring site can be increased, so the system must have the function of site extension. Site extension mistakes may occur at the initial log in. So site deletion is a necessary function. It is necessary for the host computer to have the function of sending instructions. When the engineering state needs to be known, the system sends the measure instructions. Site organization form is shown in figure 5. Figure 5. Site Organization Form 30

4.2.3 Data management The main line of the system is data. Data management includes the function of data receiving, data storage, data query and data export etc. The function of data receiving is defined as accepting the sensor information from the remote data collection module, splitting the data package according to the protocol, and taking out the useful parts of data. The function of data storage is defined as saving the data to the database in order to conveniently process data by other program in the future. The function of data query is defined as searching the history data according to the conditions of time or serial number, making simple curve analysis about the query results and printing report. The function of data export is defined as outputting the just received data, query results etc to excel sheet in order to conveniently process data. The function of curve analysis and report print is shown in figure 6 and 7 respectively. Figure 6. Curve Analysis Function Figure 7. Report Print Function 4.3. Communication protocol The communication protocol defined in this paper is not the GPRS protocol, but the user-defined protocol. It is used to describe the meaning of sending or receiving data package content. It is used to regulate the data package format between the both sides of communication objects. The system is composed of several communication objects. The data transmission style is point to multiple points. The data package, which is sent by the background host PC computer software, defines the data package s original address, destination address, data package length, measure sensor number, checksum, and redundant data bits used in the future. 31

The data package, which is sent by the remote data collection module, defines the data package original address, destination address, data package length, data package index, total batch number, checksum, and redundant data bits used in the future. The same name in the protocol is consistent with its meaning on the both sides of communication. Original address is the address of sending data package, which definitely inform the receiver of the data package source. Destination address is the address of accepting data package. The receiver will match with its own address. If the package is sent to itself, it accepts and disposes, or else throws the packet out. Data package length is used to inform the receiver of effective bit numbers of the useful data in the data package to accurately extract the useful data. Data package index and total batch number are used to solve the problem of too many data. The data can not be completely transmitted in one time. Total batch number is defined as total times of transmission. Data package index indicates transmission progress. This design is used to assure all the data can be accepted by the receiver. Checksum is a kind of arithmetic operator about all the data in the data package. It makes sure whether the data package is wrong. When it is wrong, the repeat sending begins. Redundant data bit can add new meaning conveniently when the protocol needs to be extended, such as adding information of sensor type, environment temperature etc. Both of remote data collection module software and background host computer software should comply with the same protocol, use GPRS transmission style so as to complete sensor information collection, data analysis, disposal, and reduce tedious intermediate links. This can greatly decrease the monitor difficulty of operator, release label from onerous work, and save considerable cost for the engineering. 5. Conclusion The hardware selection and system software are discussed in this paper in detail so as to demonstrate the remote civil engineering monitor system based on GPRS. On the base of developed splitter, this system integrates the remote information collection with background data management, combines remote different signal transmission style, and embeds user-defined protocol in order to realize comprehensive monitor of the engineering health state. Based on the GPRS data transmission, this system completely realizes the seamless connection of remote data collection and background management. Through the debug process, the system has been run for several months. The collection of engineering state data does not require operator to go to the measurement field. That is to say, it realizes the purpose of remote state monitor, and cost is saved. If the remote collection module is modified, the system can monitor other engineering easily. It indicates that the system has good portability and can be used in many other fields. 6. Acknowledgements The work described in this paper was funded by national science fund for young scholars (41102176). 7. Reference [1] Newson Timothy A, Delatte Norbert J, "Case methods in civil engineering teaching", Canadian Journal of Civil Engineering, vol.38, no.9, pp. 1016-1030, 2011. [2] Fröbel Toni, Firmenich Berthold, Quality assessment of coupled civil engineering applications, Advanced Engineering Informatics, vol.25, no.4, pp. 625-639, 2011. [3] SUN Hongbing, YUAN Shenfang, "Technology of Distributed Structural Health Monitoring System with Multi-layer and Multi-Agent", IJACT: International Journal of Advancements in Computing Technology, Vol. 3, No. 10, pp. 274-282, 2011. [4] Xin Yue, Zhang Zhenjiang, "A coverage holes detecting algorithm in wireless sensor networks", JCIT: Journal of Convergence Information Technology, vol.6, no.9, pp.159-168, 2011. [5] Weisheng Zhong, Yijun Li, "Design of Water-Quality Monitoring System Based on GSM", IJACT: International Journal of Advancements in Computing Technology,vol.3, no.11, pp.375-380,2011 32

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