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1 Introduction
1.1 Document construction instructions
The purpose of this program is to let integrators, engineers and users understand the design concepts, principles, overall planning and how to play a huge role in the field of intelligent transportation of the Internet of Things RFID technology, and elaborate on the working principles and installation locations of related Internet of Things equipment. Information so that integrators, engineers, and users can correctly understand the revolutionary changes brought about by the Internet of Things in the field of intelligent transportation, and establish a correct understanding of the Internet of Things in the field of intelligent transportation. If you encounter any confusion or confusion during the reading process, please contact the program writer.
1.2 Explanation of terms and abbreviations
Term explanation
RFIDRadio frequency identification is a communication technology that can identify specific targets and read and write related data through radio signals without the need to establish mechanical or optical contact between the identification system and specific targets
The RFID active radio frequency card is composed of an embedded processor and its software, a transmitting and receiving antenna in the card, a transceiver circuit and a high-energy battery. The special number is pre-stored in the microcontroller, and a unique encrypted identification code radio signal is transmitted intermittently. The high-energy battery in the card provides energy for the normal operation of the active card, and the battery in the card can be replaced.
The directional reader is composed of information collection, processing, information transmission, and embedded software. Its main function is to complete the real-time collection and processing of the vehicle identification code output signal.
The intelligent traffic control system receives the bus priority application instruction sent by the traffic signal, and realizes the delay of the green light at the intersection and the early interruption of the red light
2. Project background
2.1 Status analysis
As a new type of passenger transportation mode, the BRT system is considered to be one of the effective ways to solve the problem of urban traffic congestion due to its advantages of low project investment, short construction period, low environmental pollution, and high transportation efficiency. Successfully promoted and applied. Under the strong influence of the construction of rapid transit systems in many cities in the world and the strong promotion of relevant policies in my country, the domestic transportation industry and major cities have begun to push the rapid transit system to the forefront of alleviating urban traffic pressure. In the next 5 years, there will be 10 in China. The above cities have built a rapid transit system, which is expected to have a total length of 300 to 500 kilometers and a daily passenger flow of 2 to 4 million;
Public transportation is an important means to improve the efficiency of transportation resource utilization and alleviate traffic congestion, and it is the main direction of solving traffic problems in big cities. With the expansion of the scale of the city and the development of the economic level, the needs of urban residents to improve travel conditions, especially the convenience of public transportation, are becoming more and more urgent;
Under this background, Ren Microelectronics has vigorously developed the Internet of Things technology to improve my country’s urban public transport construction level and service quality, and developed an intelligent management system for the priority control of BRT signals based on RFID technology;
2.2 Significance of system construction
1. Reduce the travel time of public lines and reduce the delay of public vehicle intersections;
2. Reduce the number of public vehicle parking times, improve the stability and accuracy of public vehicle driving, and improve the level of public transport services;
3. Reduce the delay of social vehicles on the main line and the length of the line of vehicles;
4. Reduce vehicle energy consumption, manpower and transportation equipment;
3. System Overview
3.1 System design principles
The system development and construction follow the following principles:
Focus on overall planning
The BRT signal priority control intelligent management system consists of three parts. First, the core hardware of the BRT signal priority control system (including: 2.4G active electronic tags, directional readers). Second, the BRT signal priority control system platform (Including intersection control subsystem, signal communication subsystem, intelligent traffic control); third, hardware middleware (including signal control machines, industrial-grade switches, cabinets, PCs, servers, uninterruptible power supplies, etc.);
Based on independent research and development
The core technology of the system construction adopts the standard 2.4G active microwave frequency band commonly used in the market. All the core equipment provided by the company has completely independent intellectual property rights, 2.4G micro-power technology, automatic identification of long-distance moving vehicles and non-contact information Collection and processing, the advanced information technology, data communication technology, electronic control technology and computer processing technology are effectively and comprehensively applied to the ground transportation management system, thus establishing a large-scale, all-round function, and real-time, accurate and efficient Traffic management system. Realize the purpose of giving priority to public transport signals;
Focus on future development
In terms of the overall system architecture, service equipment selection, active electronic label function selection, basic data collection, etc., full consideration is given to the realization of subsequent functions, taking into account the compatibility of equipment, system scalability, function scalability and application Diversity
Strengthen system specifications
System development and resource construction conform to a unified technical specification and characterization system, pay attention to the continuity and sharing of development work, and pay attention to leaving standardized data and control interfaces for subsequent system development and promotion. Unified development of technical indicators such as application technology, data storage format, signal transmission format, interconnection interface mode, etc.;
Utilize construction benefits
System development and construction should combine the current actual conditions of the traffic area, and further strengthen the traffic management on the basis of the existing system; follow the overall planning, construction while using, and gradually improve the construction ideas to give full play to the construction benefits;
3.2 The working principle of the system
The BRT signal priority control intelligent management system refers to the priority given by the traffic signal system to BRT vehicles in terms of “time”, which is mainly reflected in: when the BRT vehicle drives near the intersection, the traffic signal system recognizes the vehicle and judges the vehicle’s status The direction of operation provides a priority signal for the bus.
The BRT signal priority control intelligent management system mainly includes active electronic tags and base station type directional readers. Its basic working principle and characteristics are that when the RFID base station type directional reader detects that the BRT vehicle is approaching an intersection, it sends a request signal to the intersection signal, and the RFID base station type directional reader recognizes the detected BRT vehicle. , And transmit the information to the traffic signal control system in real time through the dedicated communication optical fiber, and the traffic control system center will issue instructions to the intersection signal machine for timing adjustment. The traffic control system of BRT vehicles adopts two solutions: (1) When the BRT vehicle approaches the intersection and encounters a green light, the current green light phase time is appropriately extended by 8 seconds to ensure that the BRT vehicle passes through the intersection smoothly; (2) When the BRT vehicle approaches the intersection When the intersection encounters a red light, shorten the red light signal cycle and switch to the green light phase of BRT vehicles driving 8 seconds earlier, thereby reducing the delay time of BRT vehicles at the intersection;
3.3 Schematic diagram of overall system design
3.4 System function introduction
When the vehicle arrives at the intersection, the RFID reader reads the tag and obtains vehicle information; obtains the real-time scheduling status of the vehicle by interacting with the intelligent scheduling system, including whether it is late, whether it is express scheduling, and the full load rate, etc., and generates a request according to the real-time status of the vehicle; After that, the signal priority system submits a priority application to the traffic management department. The traffic management department system processes the request based on the original plan information and real-time scheduling information, and finally gives priority results; after the vehicle leaves the positioning area, the signal control system enters The signal state is restored to the state, until the signal state is restored, the signal priority scheduling process is completed;
3.5 System software introduction
Traffic signal control system
The traffic signal control system is an important subsystem of the intelligent traffic management system, and it plays a role of the nerve center in constructing the intelligent management system of the BRT signal priority control. When the RFID base station type directional reader detects the identity of the BRT vehicle, and transmits the information to the traffic signal control system in real time through the dedicated communication optical fiber, the traffic control system center immediately issues an instruction to the intersection signal machine for timing adjustment;
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