I. Overview
With the rapid development of China's national economy, the scale of urban construction is advancing with each passing day, urban transportation problems are becoming increasingly prominent, and it has become one of the key issues that seriously restricts the development of many large and medium-sized cities. Vigorously, give priority to the development of public transportation. Realizing digital and intelligent urban traffic management, improving the efficiency of public transportation operation management and social service levels, in line with the current development trend of modern big cities under China's national conditions.
At present, the bus intelligent management and dispatch mode of most large cities in China only adopts GPS satellite positioning technology, and a small number of cities only adopt radio frequency identification technology. The adoption of these two technologies is from static supervision to dynamic supervision, and the transition from manual management to automatic management is a manifestation of the progress of public transportation management. However, the adoption of these two technologies has their own distinct advantages and disadvantages. The effect is not very satisfactory.
The following separately analyzes the application of the two technologies of GPS and radio frequency identification in the field of public transportation, and discusses the combined use of the two technologies, so as to imagine the possibility of improving the intelligent management of public transportation.
2. GPS technology and its advantages and disadvantages cited in the field of public transport
GPS, also known as Global Positioning System (Global PosiTIoning SystemGPS), is composed of three parts: space constellation, ground control and user equipment. Its basic positioning principle is: the satellite sends its own ephemeris parameters and time without interruption, and the information user receives After the information is obtained, it is computer-aided to obtain the three-dimensional position, three-dimensional direction, movement speed and time information of the receiver. The GPS system has the following main features: all-weather, multi-function, easy operation and wide application range.
(1) Advantages of application in the field of public transportation
At present, GPS technology is relatively mature in vehicle applications. It has fast, efficient, and accurate three-dimensional coordinates of point, line, and surface elements, and has the advantages of all-weather, high precision, automation, and high efficiency. The application of GPS technology in public transportation intelligent management is mainly reflected in the subsystems such as vehicle automatic positioning, driving information guidance and electronic stop signs. The main features of GPS explained above are in line with the needs of public transportation intelligent management technology. For newly-developed large and medium-sized cities, public transportation infrastructure is relatively complete, urban roads and building distances are relatively wide, and viaducts and tunnels are relatively small. The GPS system has flexible scheduling, and the advantages of strong awareness and adaptability are fully reflected. Once it comes out, it can fully meet the management requirements of real-time control of the vehicle behavior status.
(2) Disadvantages of application in the field of public transport
At present, large cities in China with a long history and relatively high economic level, such as Beijing, Shanghai, and Guangzhou, after more than 30 years of urban construction, there are many high-rise buildings in the urban area, dense viaducts and bridges, and more and more tunnels. As the main force of urban public transportation, buses are necessary to travel through these places, and GPS satellite positioning will weaken the signal when it encounters more dense and dense sections of high-rise buildings. If there is no signal when there is an elevated bridge or tunnel, it will cause The GPS system signal is unstable or even unable to work normally. For example, Guangzhou is a typical large city with high building density, high floors, and many viaduct bridges and tunnels. At present, the GPS intelligent dispatch management system for public transit companies constructed and used by some public transport companies in Guangzhou, once used, passes through the ground floor of viaduct bridges, Such vehicles have been encountered in tunnels, or bus stops at the bus stops near viaducts and bridges, and enter the bus station of the tiered passenger and vehicle diversion hub.
The problem of unstable or no signal makes the dispatch center unable to know the bus's behavior status at this time.
3. The advantages and disadvantages of radio frequency identification technology and its application in the field of public transportation
Radio frequency identification technology [Radio Frequency [denTIficaTIon, abbreviated as I II) (For more information? Please refer to this issue [Technical "new words" explanation)) 1 is to automatically identify the target object and obtain relevant data by radio frequency signal , Card reader and signal transmitting antenna are composed of three basic parts. Its working principle is: when the radio frequency card enters the transceiver antenna area, the encrypted carrier signal sent out is received by the antenna, after receiving and processing by the RFID radio frequency card reader device, the obtained card information is sent to the communication module.
(1) Advantages of application in the field of public transportation
The main purpose of using radio frequency identification technology is to achieve automatic identification of long distances without stopping, real-time fixed-point collection of bus entrances and exits and through information collection points to quickly determine the location of bus vehicles. Its main advantages are: Car radio frequency cards and card readers basically use two-way interactive wireless data communication mode, the communication technology is stable and reliable, and the bit error rate is extremely low. Carrier signal penetration, strong diffraction force and information anti-collision function are very good. Car radio frequency card can be fixedly installed on the surface of metal, non-metallic, glass and other objects of the vehicle, the installation position is basically unlimited, and the card reader can be simultaneously Identify multiple vehicle cards that are not walking side by side, cross lanes, cross lines, crawl heads, etc. The induction range and passing speed of the car radio frequency card and the card reading device can also be flexibly adjusted according to management needs.
(2) Disadvantages of application in the field of public transport
The shortcomings of the application of radio frequency identification technology in the field of public transportation are mainly reflected in the fact that data can only be collected at a fixed point. The "point positioning" method of the technology has strong limitations. Compared with the use of GPS technology, it is flexible. Behind. If the data collection equipment is installed intensively, the capital investment will be quite large, and the maintenance cost after completion is also very expensive; if the data collection equipment is too few, the sensing range is not fully covered, and the real-time status information of the vehicle driving on the road cannot be realized.
4. Improve the reliability of the public transportation intelligent dispatch management system through the combination of GPS and RFID
The public transportation intelligent dispatch management system can adopt the design scheme combining GPS technology and radio frequency identification technology. Because the coverage of GPS signals is relatively wide at present, the GPS satellite positioning system can be used as the main method, and the radio frequency identification technology can be used as a supplement. According to the analysis of the advantages and disadvantages of the above two technologies in the field of public transportation, the advantages of radio frequency identification technology can be used to make up for the shortcomings of the application of GPS technology. The first use of data information from the background management subsystem of the dispatching command center comes from the GPS subsystem, and the second use of data information comes from the radio frequency identification subsystem. Under the premise of sufficient data information sources, the reliability of the public transportation intelligent dispatch management system will also be better improved. The main framework of the system is as follows:
(1) Bus on-board equipment
A set of GPS equipment and an RF card are installed on the bus at the same time. The price of an RF card on the market currently ranges from 50 to 80 yuan, which is very low compared to the price of on-board GPS equipment. It is reliable for improving the system. Sexually, this investment is well worth it.
(2) RF information collection and transmission equipment
It is mainly installed in an appropriate location where the GPS signal cannot cover or is relatively weak. The device consists of a radio frequency transceiver antenna, a card reader, and a communication module. Its working principle is: after the vehicle-mounted radio frequency card enters the transceiver antenna area, the encrypted carrier signal sent by the vehicle-mounted radio frequency card is received by the antenna, and after receiving and processing by the RFID radio frequency card reader device, the vehicle radio frequency card information obtained is sent to the communication module. The communication module establishes a communication connection with the remote card reader server through the GSM / GPRS / CDMA wireless network, and transmits the received card number, time, and address information to the dispatch center.
The communication module mainly relies on GsM / GPRs / CDMA and other digital public network communications, with IP address settings, card reading data cache / comparison E local card number limit filtering, remote communication timeout / abnormal alarm, clock / card number set / abnormal alarm SMS remote setting And other functions. In view of the importance of data communication, in order to ensure the stability and reliability of wireless communication, the communication module here requires the GSM / GPRS / CDMA working module to provide hot backup as the second channel.
(3) Dispatching command center system
The dispatching command center system is composed of network communication equipment, data reception, storage, analysis, management, publishing server, large-screen TV wall, client management computer and other equipment. The background management subsystem is screened and analyzed based on the positioning data and status information of the bus vehicles received in real time, and the management personnel of the dispatch command center can immediately make a quick and reasonable dispatch instruction, and at the same time send information to the subsystems Publish timely service information. For the collected data, the background management subsystem automatically summarizes and statistics, and generates various operating reports.
V. Summary
In view of the current bus intelligent management and dispatch mode of some big cities in China, the combination of GPS and RFID proposed here to improve the reliability of the bus intelligent dispatch management system is an attempt to better serve high-tech means to the city An assumption of digitizing public transportation. Aiming at the GPS public transportation intelligent dispatch management system that has been constructed in some cities. Using the "point positioning" system based on radio frequency identification technology as a supplement can not only improve vehicle positioning accuracy, but also improve the operation efficiency and service level of bus system enterprises. It can also overcome the deficiencies of GPS satellite positioning system in public transport applications. Reduce capital investment.
Transportation is the economic artery. Modern science and technology should be used to transform the traditional bus industry, and informationization should be used to drive modernization. Building a new type of intelligence. Automated bus dispatch management system, the "transit priority" policy conforms to China's current national conditions, represents the interests of most people, and can maximize the potential of existing urban roads. It is an important way for government traffic management departments to solve urban traffic problems. The management and service of the public transport system will be improved to a new level, and at the same time, it will be able to assist government functional departments to effectively manage and plan the overall operation of the public transport system.
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