GPRS

JOURNAL OF CHINA UNIVERSITY OF

MINING & TECHNOLOGY J China Univ Mining & Technol 18 (2008) 0288–0292 www.elsevier.com/locate/jcumt

Monitoring dispatch information system of trucks and shovels in an open pit based on GIS/GPS/GPRS GU Qing-hua1, LU Cai-wu1, LI Fa-ben2, WAN Chang-yong2 1

School of Management, Xi’an University of Architecture & Technology, Xi’an, Shaanxi 710055, China 2 Luoyang Luanchuan Molybdenum Industry Group, Inc., Luoyang, Henan 471500, China

Abstract: Using GIS, GPS and GPRS, an intelligent monitoring and dispatch system of trucks and shovels in an open pit has been designed and developed. The system can monitor and dispatch open-pit trucks and shovels and play back their historical paths. An intelligent data algorithm is proposed in a practical application. The algorithm can count the times of deliveries of trucks and loadings of shovels. Experiments on real scenes show that the performance of this system is stable and can satisfy production standards in open pits. Key words: GIS; GPS; GPRS; dispatch; data processing; open pit

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Introduction

To date the development of truck monitoring dispatch systems in the world, such as the DISPATCH monitoring system of the American Module Company has reached a highly mature level and is almost universal. It has developed into a decision-making platform by management as a control system in multi-directional mining production, called Intellimine. In 1998, DISPATCH was introduced into the Dexing Copper Mine in Jiangxi, China[1]. It has clearly enhanced the service efficiency of equipment, improved the management level in the open pits and obtained better overall benefits. In 2003, the Dandong Dongfang Measurement and Control Technology Co. Ltd., together with the Qidashan Iron Mine have developed a dispatch management system for trucks in open pits. The system has become indispensable to daily production management. It must be emphatically pointed out that the greatest disadvantage of these systems is that they cost too much. The major cause is that an independent communication network needs to be established and maintained by every open pit. Many mines can not afford such a system. However, using GIS/GPS/GPRS technologies, it is not necessary to establish independent communication networks in every open pit. The network can be maintained and upgraded by a third party (e.g., China Mobile Communication Co. Ltd). This can reduce costs considerably and provides a good platform for

medium and small open pit mines to establish a fast, highly effective, and practical ground transportation system. Such a system is very important in enhancing labor productivity, reduce mining costs and promote mining technologies to an unprecedented level in open pits.

2 2.1

GIS/GPS/GPRS GIS

The Geographic Information System (GIS) is one kind of computer system gathering, storing, managing, analyzing, demonstrating and applying geographic information. It is a general technology that can analyze and process enormous amounts of geographic data. It takes a geographic space database as its foundation, uses a geographic model analysis method to provide many kinds of spatial and dynamic geographic information and serves as a geographic research and decision-making tool. It has some basic functions such as electronic mapping, spatial data management and spatial information analysis. GIS has been applied in many fields to establish all kinds of spatial databases and decision support systems, each with different criteria and provide answers to many different formal spatial inquiries, spatial analyses and assistance plans and decision-making functions. To date, GIS has been gradually applied in open pits[2–3]. The task of a monitoring dispatch informa-

Received 16 September 2007; accepted 15 January 2008 Corresponding author. Tel: +86-29-82204746; E-mail address: [email protected]

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Monitoring dispatch information system of trucks and shovels in an open pit …

tion system of trucks and shovels in open pits is to track, monitor and manage production equipment, which depends largely on geographic spatial information. Therefore GIS plays an important role in visual supervisory systems of trucks, real-time dynamic management and assistance in decision analysis. 2.2

GPS

The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites placed in orbit. Their ground stations are managed by the U.S. Department of Defense[4]. A GPS receiver must be locked on to the signal of at least three satellites to calculate a 2D position (latitude and longitude) and track movements. With four or more satellites in view, the receiver can determine the 3D position of trucks (latitude, longitude and elevation). Once the position of the truck has been determined, the GPS unit can calculate other information, such as speed, bearing, track, trip distance, sunrise and sunset time and more. GPS works in all weather conditions, anywhere in the world, 24 hours a day. There are no subscription fees or establishment charges to use GPS. To date, as GPS units are becoming smaller and less expensive, there are an expanding number of applications for GPS in open pits. With GPS, the monitoring dispatch information system of trucks and shovels in open pits provides accurate position (latitude and longitude), speed, bearing, time, track and more basic information of trucks and shovels. 2.3

GPRS

The General Packet Radio Service (GPRS) is one of GSMPhase2+ standard realization contents and can provide fast data transmission speed. Theoretically, this service is ten times faster than the current Circuit Switched Data services on GSM networks. GPRS uses the same frequency range, bandwidth, sharpedged structure, wireless modulation standard, frequency-hopping rule and TDMA frame structure as GSM[5]. GPRS involves overlaying a packet based air interface on the existing circuit switched GSM network. It provides end-to-end, wide area wireless IP connection. GPRS uses fully shared wireless channels and provides faster and long-distance connection for data terminals by IP over PPP. It provides four kinds of Qos and supports the protocol of IP and X.25. It can communicate with the internet and other public data networks. As a transition technology (2.5G) from GSM to the third generation mobile communication, GPRS has remarkable advantages in many aspects. The monitoring dispatch information system of trucks and shovels in open pits largely uses the advantages of GPRS such as faster speed and instant connections as the need arises and charging by amount of data. It can provide real-time wireless

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transmission and is very quick without a dial-up modem connection to GPS equipment for position information. That is very important because GPS position information has room for only a small amount of data and needs to be transmitted frequently. So this system can make good use of GPRS to transmit GPS position information.

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Principle of monitoring dispatch system of trucks and shovels

3.1 Monitoring dispatch system of trucks and shovels The monitoring dispatch system is composed of mobile terminals carried by vehicles, a communication network and a monitoring center, as shown in Fig. 1. In this system the mobile terminals receive GPS signals and then calculate the latitude, longitude, angle, elevation and speed of the vehicles. The expansion interfaces of mobile terminals can also meet many examination and control lines to obtain the information from the vehicles. Each kind of information is transmitted to the monitoring center through GPRS and the internet. GPRS, as a telecommunications network between the mobile terminals and monitoring center, mainly transmits the information on position and condition of the vehicle and information in case of an alarm, to the monitoring center, which in turn transmits dispatch and control commands to the vehicles. In the monitoring center, the communication server, the database server and the console are connected by a 100M local area network. The monitoring center under control of the system software system receives and processes all kinds of information coming from the controlled vehicles. The position, paths and other information of the vehicles are displayed at LED multimedia monitors and electronic maps in the monitoring center and from these the vehicles can be monitored and dispatched. Besides, the system may establish other centers with monitoring and dispatch subsystems in different regions. This sub-center with independent or relatively independent monitoring dispatch functions can be controlled from the center[6] .

Fig. 1

Monitoring dispatch system structure

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3.2 Data processing system of trucks and shovels The data processing system of trucks and shovels at first locates the real-time positions of trucks through GPS and GPRS and then determines the loading mine position A (longitude, latitude) through a terminal on the shovel and the unloading mine position B (longitude, latitude) through GPS equipment. The real-time location of truck C (longitude, latitude) can be determined according to a terminal installed in the truck, as shown in Fig. 2.

Fig. 2

Schematic data algorithm

The following steps take time series as their benchmark. Assume that Distance(C, X) is the distance between truck C and each shovel, R1 is the scanning distance of shovel A and R2 the scanning distance of crushing station B. The value of R1 and R2 depends on the actual situation in an open pit and the shape of the scanning region. Assume also that both scanning regions are circular and their radii R1 and R2. F1 and F2 are two variables. The algorithm follows. 1) Scan all the GPS data of the truck from the starting time or last scanning time. First, filter the repeated GPS data of the truck and only save a record of GPS data if the truck has many similar records of GPS data in one place. Then filter the GPS data which does not belong to the scanning regions in the process of traffic. Data conforming to these two conditions will be further filtered according to the next three steps. The initial values of F1 and F2 are deliberately set as false. 2) According to the time of the GPS data of the truck, the position of the shovel at the same or nearest time is searched. Then the Distance(C, A) between the truck and the shovel is extracted. The algorithm decides whether Distance(C, A) belongs to the scanning region of the shovel which is determined according to the actual situation in the open pit. Decide whether Distance(C, A)
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A)>R1. 4) The coordinates of the crushing station can be surveyed by GPS and then extract the minimum Distance(C, B) between the truck and the crushing station. Decide whether Distance(C, B) belongs to the scanning region of the crushing station which is also determined according to the actual situation in the open pit. Decide whether Distance(C, B)R2. 6) When Distance(C, B)>R2, judge F1 and F2. Only if F1 and F2 are both true at the same time, record one time for the truck (C), the shovel (A) and the crushing station (B) according to this information. The values of F1 and F2 must be reset as false and the algorithm continues to execute the next loop. If these steps are executed in the correct order, the system can compute the times between shovel and crushing station accurately. Besides, for determining the real-time positions of trucks and shovels, the feedback time of the positional information is usually 10 seconds. The system will have an enormous amount of redundant data. This massive amount of data needs a highly efficient algorithm. In actual development we adopted some optimal methods to filter the data regularly and automatically, which can greatly reduce the amount of redundant data and enhance its efficiency. Moreover, the scanning regions can be set as a different, random polygon according to the actual situation. Its principle is similar as that described.

4

Monitoring dispatch information system of trucks and shovels in Sandaozhuang open pit

The Sandaozhuang open pit is part of the Luoyang Luanchuan Molybdenum Industry Group Inc. Its output is 10 million tons. Its length is 2350 m, its width 1350 m and its mining elevation is between 1114 and 1630.8 m. The height of mining is 516.8 m and the bench height 12 m. Rotary drilling machines, shovels and trucks are used in this mining process. The transportation system consists of a number of trucks, a crushing station, an ore pass and electric locomotives. The monitoring dispatch information system of trucks and shovels in this open pit consists mainly of terminals and monitoring dispatch software. 4.1 Software constitution and its function 4.1.1 GIS monitoring dispatch client (GMDC)

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Monitoring dispatch information system of trucks and shovels in an open pit …

The GIS monitoring dispatch client can be installed in the monitoring center to manage, dispatch and monitor trucks and shovels. Its functions are as follows: 1) Map operation: zoom in, zoom out, roam and display lamination maps; display coordinates of a random point on the map; compute the distance of two random points; compute the area of a random polygon; inquire about the geographic target information etc. 2) Vehicles display: display the several trucks or shovels differently, e.g., different colors and different marks; do not display trucks or shovels according to given commands. 3) Playback of historical paths: play back the travel path of any truck at some time on the electronic map. 4) Inquiry about the location of a truck: inquire current position, speed, condition and driver of any truck at any moment. 5) Instruction dispatch: the monitoring center can send out dispatch instructions as text; the terminal carried by trucks will clearly indicate and display, with a red light, the dispatch instructions on the terminal. 6) Pronunciation dispatch: the monitoring center can call any terminal carried by vehicles for dispatch; the red light of the terminal will clearly indicate that instructions are given and will ring. 7) Terminal information feedback: the terminal carried by trucks can upload the prefabricated fixed information on the operation surface of the terminal and return feedback to the monitoring center which can deal with the information in a timely fashion. 4.1.2 GPS data processing client (GDPC) The function of the GPS data processing is to record the times delivered by trucks and the times loaded by shovels. The concrete function is as follows: 1) Count of delivery by truck: count accurately the delivery times of each truck from shovels to crushing stations during some time interval; the interval can be set by users; the statistical results can be transformed to report forms by class, month and season, according to need of the user. 2) Count of loading by shovels: count accurately the loading time during some time interval of each shovel; other functions are the same as in 1). 4.1.3 GPS localization data processing server (GLDP) The function of the GPS processing server is mainly to filter, extract and process the localization data of trucks and shovels in order to enhance the level of accuracy and statistical efficiency. 4.1.4 Data communication control server (DCCS) The communication control server mainly gathers, transmits and routes the data through the TCP/IP and analyzes the communication protocol and the distribution of data; this part is also in charge of the handling of traffic (monitoring, dispatch etc.) and other

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data connections (the localization data input, condition, renewal of vehicles, etc.). 4.1.5 Database management system (DBMS) The database management system mainly manages the database and increases, deletes, modifies and requires data from vehicles, drivers and operators; it regularly backs up the data and then deletes it. 4.2 System application deployment The process of the entire system deployment is as follows: 1) Early preparation: the terrain of the open pit is complex, the communication signals are bad and there are many blind signal zones. A communication base seat and a repeater were built by China Mobile. These measures have solved the signal problem. 2) Terminal installation: the type of terminals is a HQ60006-T10 provided by the Shenzhen Huaqiang Holdings Ltd. GPS terminals had been installed in 75 trucks and shovels during an earlier period. The terminal consist mainly of a mainframe, a GPS antenna, a GPRS antenna, a display, a red indicating lamp, earphones, a sound box as well as a microphone. After installation, the terminal needed debugging. It mainly sets the parameters of the main frame (number, IP, port, etc.) using an operation handle. 3) Software deployment: there are five sub-systems in the project. A schematic deployment structure is drawn in Fig. 3. The data communication control system is deployed in the web server of the company; the localization data processing system and the database management server are deployed in the database server of the company; the data processing client and the monitoring client of trucks and shovels are deployed in the monitoring center of the open pit.

Fig. 3

Schematic deployment structure

4) Coordinate registration: in first instance, the present topographic map of the open pit should be renewed. Under AutoCAD2006 we can transform it from DWG to DXF format. Then we can match the present DXF topographic map to the coordinates. Establish a longitude/latitude (wgs84) coordinate system and select a couple of coordinates: the geodetic coordinates of the first point are: (6755.3044, 4850.7990), latitude/longitude coordinates (111.506202, 33.91905); those of the second point are (6459.1221, 5482.2094), latitude/longitude coordinate (111.50295, 33.92468). Their match is shown in Fig. 4. After obtaining the

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electronic map of Tab format, the electronic map is saved as Geoset by MapX5.0.

Fig. 4

Coordinate registration

5) System debugging: Many parameters need to be rationalised in this system, given the real situation. The most important parameters are the demarcations of all the scanning regions in the open pit. At present there are five scanning regions, those of crushing stations I, II, III, the Nangou trough and the reserve mine. They have mainly adopted the method of scanning return paths made by many trucks to determine the areas. Besides, in some special terrain, scanning regions of irregular shapes can be determined by means of points and straight lines. Fig. 5 is the operation interface of the software system.

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Conclusions

1) Based on GIS/GPS/GPRS technologies, the monitoring dispatch information system of trucks and shovels in an open pit is a set of multi-directional, real-time, highly effective software system. The practical application indicates that the system improves labor productivity and the production scheduling efficiency in mines considerably and saves investment and transportation costs. 2) From GPS pinpoint data, the system can determine the delivery times of trucks and loading times of shovels. Its level of accuracy is 99%–100%. The system saves considerably on labor costs, reduces the effect of human factors on production scheduling and provides an accurate basis for matching ore plans. 3) The system is of great importance in the realization of automation in truck and information management in open pits, which definitely can be applied to other open pits.

Acknowledgements The authors gratefully acknowledge the cooperation of the Luoyang Luanchuan Molybdenum Industry Group Inc and Shenzhen Huaqiang Holdings Limited. The authors also thank other participants for their support.

References Fig. 5

Software operation surface

[1]

4.3 Running the system The monitoring dispatch information system in the Sandaozhuang open pit has been used since March, 2007. Some problems have arisen since then, such as drift and precision of GPS. These have been solved by optimization of the system software. After experiments with real scenes, the performance of the system is stable. It not only can track and localize trucks, play back historical paths, monitor the trucks automatically, but can also dispatch the trucks by voice and instructions, count the workload of trucks and shovels accurately. Fig. 6 shows some results of the data system of trucks.

[2]

[3]

[4]

[5]

[6]

Fig. 6

Output data of trucks

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