Introduction to the application of RFID and ETC two emerging technologies in access control systems
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In 2009, Premier Wen Jiabao pointed out in his speech on “Let Science and Technology Lead China’s Sustainable Development”: It is necessary to focus on breakthroughs in key technologies of sensor networks and the Internet of Things, and early deployment of related technology research and development in the post-IP era, so that the information network industry will become a promotion of industrial upgrading. , Towards the engine of the information society. Since the opening of the 2010 Shanghai World Expo, the cumulative number of tourists received has exceeded 12 million, which means that more than 12 million Expo tickets have passed through the ticket gates, leading tourists on a world tour. Chen Jianbo, vice president of Shanghai Huahong Group, the designer and manufacturer of Expo tickets, said: “It can be said that the core technology with independent intellectual property rights,’Expo Core’, made Expo tickets pass the entrance examination.” “Expo Core” is the first large-scale comprehensive application of radio frequency identification technology (RFID technology), which proves that my country’s RFID technology is quite mature.
1 Related technology
1.1 Radio Frequency Identification
RFID (Radio Frequency Identification, radio frequency identification) is a non-contact automatic identification technology that automatically recognizes target objects and obtains related data through radio frequency signals. It can quickly track items and exchange data without human intervention.
As a new technology, RFID is a combination of radio technology and radar technology. In 1948, Harry Stockman published “Communications Using Reflected Power”, which laid the theoretical foundation for radio frequency identification RFID. The technology that laid the foundation for RFID was first developed in World War II. At that time, in order to identify the aircraft, it was also called the “friend and enemy” recognition technology, and subsequent versions of this technology are still used in aircraft recognition.
A typical RFID system includes three main components: electronic tags, readers (including antennas), and application systems. The electronic tag is the data carrier of the radio frequency identification system. It is composed of a tag antenna and a tag-specific chip. It can receive the electromagnetic field modulation signal of the reader and return a response signal to realize the read or write operation of the tag identification code and memory data. The reader is used to receive commands from the host and transmit the data stored in the sensor back to the host in a wired or wireless manner. It contains a controller and an antenna. If the reading distance is long, the antenna will exist alone. The application system refers to the user’s original MIS system. The terminal computer of the application system that interacts with the RFID system transmits the work instructions issued by the application system, and controls the coordination between the electronic tag and the reader through the middleware, processes all the data collected by the RFID system, and performs calculations and storage And data transmission.
The working principle of the RFID system is: when an item with an electronic tag enters the radiation range of the reader’s antenna, it receives the radio frequency signal sent by the reader. Passive electronic tags use the energy obtained by the induced current to send out the data stored in the tag chip, and active electronic tags actively send the data stored in the tag chip. The reader is generally equipped with a certain function of middleware, which can read Take the data, decode it, and directly perform simple data processing, and then send it to the application system. The application system judges the legitimacy of the electronic label based on logical operations, and performs corresponding processing and control for different settings, thereby realizing the basic functions of the RFID system.
1.2 RFID tags
The radio frequency tag is the radio frequency card, also known as the non-contact IC card. It consists of an IC chip and an inductive antenna. The chip and antenna are not exposed and are packaged in a standard PVC card. The reading and writing process of the radio frequency card is usually completed by radio waves between the radio frequency card and the reader. It successfully combined radio frequency identification technology and IC card technology, and ended the two major technical problems of passive and contact-free. This is a major breakthrough in the field of electronic devices.
According to the power supply mode of the tag, the radio frequency tag can be divided into two forms: active and passive. Active tags use the energy provided by the power supply in the tag, and the identification distance is relatively long (up to tens of meters or even hundreds of meters), but the life span is limited and the cost is high. The passive tag does not contain a power source, and obtains energy from the electromagnetic field of the reader during operation. It is light in weight, small in size, long in life, and low in cost, but the communication distance is limited.
According to different operating frequencies, RFID systems can be divided into low frequency, medium high frequency, ultra high frequency and microwave systems. The working frequency of low frequency system is generally 30KHz～300KHz, and its typical working frequency is 125KHz and 133KHz. Its basic characteristics are the lower cost of the tag, less data stored in the tag, shorter reading and writing distance (about 10cm), various tag shapes, and low directivity of the reading antenna. It is mainly used in animal husbandry and animal management. The working frequency of medium and high frequency system is generally 3MHz～30MHz, and its typical working frequency is 13.56MHz. Its basic characteristics are the low cost of tags and readers, a large amount of data stored in the tags, a long reading and writing distance (up to 1m or more), strong adaptability, generally card-shaped, readers and tags The antennas have a certain degree of directivity, and are mainly used in second-generation ID card systems and all-in-one card systems. The operating frequency of UHF and microwave systems is generally 300MHz～3GHz or greater than 3GHz. Its typical operating frequencies are 433MHz, 915MHz, 2.45GHz and 5.8GHz. According to the characteristics of each frequency band, it can be applied to different occasions. For example, 433MHz active tags are often used in the fields of short-distance communication and industrial control. 915MHz is the first choice in the field of passive tag logistics. In addition to being widely used in short-distance communication, 2.45GHz is also widely used in my country’s railway transportation identification management. The 5.8GHz RFID system is used as the working frequency band of my country’s ETC, and has taken the lead in formulating the national ETC standard.
1.3 Electronic toll collection system
ETC (Electronic Toll Collection, Electronic Toll Collection) is an advanced toll collection method that is currently being strongly promoted by all countries in the world. Vehicle owners only need to install electronic tags on the windows. When the vehicle passes through the toll station, the reader set at the toll station reads and writes the electronic tags of the passing vehicle, and automatically reads from the pre-bound radio frequency card or bank account. After deducting the corresponding fees, the owner can quickly pass the toll station without parking and manual payment, and the road is truly smooth.
The ETC system is mainly composed of an automatic vehicle identification system, a central management system and other auxiliary facilities. Among them, the vehicle automatic identification system is composed of OBU (On board unit), RSU (Road side unit, road side unit), loop sensor and so on. OBU (Electronic Tag) stores the relevant information of the vehicle and is generally installed on the front windshield of the vehicle. RSU (ie reader) is installed next to the toll station. The loop sensor is installed under the road surface. The central management system stores a large amount of information about registered vehicles and owners. When the vehicle passes through the toll gate, the loop sensor senses the vehicle, the RSU sends out an inquiry signal, the OBU responds, and conducts two-way communication and data exchange. The central management system obtains the vehicle identification information and compares and judges, and controls according to different situations. The management system generates different operations to realize the automatic management of moving vehicles.
The ETC system uses a dedicated DSRC (dedicated short-range communication) method to exchange through long distances (10m～30m), a complete encrypted communication mechanism (supports 3DES, RSA algorithms), and a non-contact method (working frequency band supports 915MHz, 2.45GHz and 5.8GHz) The ETC information realizes the automatic identification of the vehicle in a fast-moving state, so as to realize the automatic management of the target.
Compared with the previous manual charging system, the current ETC system has the following advantages: First, the traffic is smoother. Drivers can automatically pay tolls directly through the ETC system without stopping, which effectively improves the vehicle capacity of toll stations, avoids traffic jams caused by toll stations, and improves highway utilization. Second, payment is convenient and transparent. Drivers paying fees through the ETC system means that there will be more vehicles passing in a unit time, which speeds up the speed of payment, improves the efficiency of payment, and also eliminates the occurrence of corruption in the payment work. Third, energy saving and environmental protection. The ETC system reduces the waiting time for vehicles to pay manually at toll stations, reduces fuel consumption, and reduces exhaust emissions when vehicles are idling, thus achieving the effects of saving energy and protecting the environment.
The mature application of the ETC system has laid a solid foundation for future intelligent transportation. Recently, this technology has also been applied to the peak congestion charging in the central area of the city.
2 Application case
Today, the vast majority of access control systems (including garage access control and building access control) are still using high-frequency radio frequency cards for management. At present, the garage access control system and the building access control system have the following problems in the use process.
The theoretical recognition distance range of the high-frequency radio frequency card is only 2.5cm～10cm (the distance between the radio frequency card and the card reader). Affected by the environment, the actual recognition distance is shorter than the theoretical recognition distance.
For the garage access control system, the location of the parking barrier ticket box requires the driver to drive the vehicle, the location of the main cab and the parking barrier ticket box location close to the card, thereby increasing the driver’s driving Difficulty, especially the parking barrier ticket box is set at the entrance of the garage with a flat ground on one side and a slope on the other. Some drivers simply swiped their cards first, erected the parking brake levers, and then went to the garage to start the car and drove out of the garage. In addition, the parking barrier ticket box is generally set at the entrance of the garage, which is close to the open environment, and has poor waterproof and moisture-proof performance against thunderstorms, which increases the failure rate of the electrical components in the ticket box and causes the parking barrier to fail to rise and fall normally.
For the building access control system, the distance between the radio frequency card and the card reader must be quite close to enable the access control to be opened, especially when people enter the building from outdoors in thunderstorm weather, which prolongs the waiting time for people to pass the building access control .
In view of some of the problems in the current access control system, we learn from the mature application experience of the highway electronic toll collection system based on RFID technology, and apply ETC technology to the current access control system (using the non-stop function module in the ETC system to cancel the ETC system Toll function module), in order to improve the level of intelligence and efficiency of the access control system, the following solutions are proposed.
⑴ Disable the high-frequency radio frequency card currently used in the garage access control system (working frequency band: 13.56MHz, identification distance range: 2.5cm～10cm), enable microwave radio frequency card (working frequency band: 5.8GHz, identification distance range: 10m～30m) . The three sets of antennas of the microwave reader-writer are installed in the shape of “products” on the top and both sides of the wall of the entrance and exit of the garage to fully collect the relevant information of the microwave radio frequency card of the vehicle.
⑵ Cancel the charging function module in the ETC system, and add video image recognition and voice alarm modules. When the vehicle passes the pre-buried ground induction coil, the vehicle automatic identification (including radio frequency identification and license plate image recognition) system in the ETC system automatically recognizes the vehicle. If the vehicle is recognized as a registered vehicle in the garage, the parking brake lever is automatically erected and released; if the vehicle is recognized as an unregistered vehicle in the garage, the central management system will promptly alarm and record a log to remind security personnel to be present on site in time .
⑶ Disable the high-frequency radio frequency card used in the building access control system, and enable the microwave radio frequency card in the ETC system. The microwave reader/writer is installed at the entrance of the building to collect the relevant information of the microwave radio frequency card. The infrared induction trigger is used to replace the ground induction coil trigger in the ETC system. When a person passes by, infrared induction triggers the microwave reader to automatically identify the person carrying the microwave radio frequency card. If it is confirmed that it is the registered personnel information of the building, the building access control will be automatically opened in advance.
⑷ For the entry and exit of temporary vehicles and temporary personnel, the administrator can issue temporary microwave radio frequency cards to solve the problem.
3 concluding remarks
RFID technology is an emerging automatic identification technology. In particular, microwave radio frequency technology has attracted attention from all walks of life due to its advantages of barrier-free reading and long-distance penetration, fast scanning, high storage capacity, small size, and good security and confidentiality. It stands out from many automatic identification technologies. , It is widely used in various fields and has huge development potential in our country. Draw lessons from the mature application experience of the electronic non-stop toll collection system of expressways, use microwave radio frequency technology to replace the high frequency radio frequency technology widely used in the current access control system, and apply ETC technology to the above access control system to improve the intelligence and efficiency of the access control system化 level.
ETC technology has broad application prospects in access control systems, for example, it is gradually being promoted and applied in intelligent parking lot management. However, for multiple access controls within the building that are very close to each other, due to the overlap of the infrared sensing range, multiple microwave readers will be triggered at the same time, which leads to the problem that workers who have the authority to these access controls can open multiple access controls at the same time. Further research and solve it.
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