As an important means of traffic automation management, and an important part of vehicle detection system, license plate recognition technology gives recognition results in the form of computer processing, which makes the computerized supervision of vehicles become a reality, and it occupies in traffic monitoring and control. Very important position.
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Development trend of license plate recognition system
Video image processing from the industrial computer to the DSP to the smart camera, the machine integrates the development of high-speed DSP processing chip; video image transmission will be transferred from the image data to the back-end host for image acquisition, recognition processing, data storage, etc. In the camera, the image acquisition, processing, storage and communication of the HD camera are integrated;
·The license plate recognition software is constantly updated, the accuracy rate is increased to 98%, the identification license plate type is increasing, and it can identify special license plates such as agricultural license plates, civil aviation license plates and overseas license plates.
· The scope of monitoring extends from the license plate of the motor vehicle to the characteristics of the vehicle body and the characteristics of the passengers;
· Further application of video detection technology represented by body color recognition;
· The fill light mode is developed from constant illumination to flash to LED light;
· Vehicle detection mode is developed from loop coil detection to video detection;
· The range and accuracy of vehicle speed measurement continue to increase, from coil speed measurement to video-assisted speed measurement;
· License plate recognition is developed from a single capture recognition to multiple recognition of the video stream;
· Pay attention to environmental protection and energy saving, and reduce the impact on drivers;
·The license plate recognition is more professional, the equipment maintenance is more convenient, the after-sales service is more professional, and the network coverage is wider.
Vehicle license plate recognition system application range
The license plate recognition system has developed rapidly in recent years, and it has been applied in various places. Its application scope is mainly in the four aspects of urban traffic management, highway toll management, highway over-limit treatment, and other applications.
I. Urban traffic management
1, security card mouth
The security card system must meet the actual needs of the criminal investigation, economic investigation, anti-drug, public security, national security, and various business departments, and provide practical application functions that can become a powerful weapon for the * management department.
Most of the security card bays are set on the road sections, some of them are set on the toll lanes of highway toll stations, and the security bayonet system is networked.
2, violation of the red light capture system
The license plate recognition system is also often installed at traffic intersections, commonly known as electronic* systems. It was evolved from the initial simple red light capture to the current bayonet recording function and video capture and capture of multiple violations of the comprehensive monitoring system, including speeding , violation of the rules of the yellow line, parking in the restricted area, retrograde, speed, blacklist alarm and many other content.
3, mobile inspection system
The license plate recognition system can be installed in a moving vehicle. It is not affected by the climate and the site, and is flexible and easy to collect. It can identify the license plate information of passing vehicles at any position in the road. It is a mobile security card.
4. Travel information publishing system such as travel time
With the deepening of urban traffic intelligence, Intelligent Transportation Systems (ITS) is developing towards information services. The current ITS system requires real-time collection and timely release of road traffic information. By allowing road users to pass through the information board, they can know the running time, running speed, and blocking length from A to B. In addition, information on each intersection can be known through in-vehicle broadcasting and roadside broadcasting. This information is automatically converted to text if an in-vehicle terminal is installed.
5, congestion charging system
Recently, major cities such as Shanghai and Guangzhou announced that they will study more comprehensive control measures and reasonable scale of motor vehicles based on market demand and road capacity, and implement “road congestion charges†when appropriate.
Shanghai will select some downtown areas to restrict private cars from driving at specific times, thereby expanding the road rights of buses and increasing the speed of buses. It is predicted that in the area where “crowding charges†are implemented, the traffic volume is expected to decrease by 10% to 20%, and the average speed will increase by 15% to 25%.
Cities such as Singapore and London have already implemented congestion in traffic congestion zones, and London’s congestion charging system uses license plate recognition technology.
The license plate recognition technology applied to the urban road congestion charging system does not require any installation of on-board equipment, which can reduce a large initial investment, but the congestion charging system has a very high requirement for license plate recognition.
Second, highway toll management
1. Network charging system
There are some problems in the current charging system: such as the exchange of cards between drivers, causing the loss of tolls; the toll collectors cheating the car, causing the loss of tolls; the toll collectors hand-printing license plates, the workload is large, and error-prone; free There is no information management for cars and blacklist cars.
The system installs the license plate identifier in the entrance and exit lanes, which can solve the above problems, prevent the drivers from changing cards and avoid the loss of tolls. The auxiliary vehicle classification automatically establishes the model library corresponding to the license plate and the model one by one to prevent the vehicle from downshifting; the license plate information Automatic identification, toll check, avoid mistakes; establish a free vehicle database, only vehicles in the free vehicle database can be released free of charge; establish a blacklist vehicle database, when the blacklist vehicle passes the exit, the system will automatically alarm, prompt relevant deal with.
2, multi-path identification split account system
In the construction of networked charging systems, they are faced with multi-path identification and settlement problems. In the networked charging environment, there is inevitably a highway loop situation, that is, the vehicle can travel from one point to the destination through different lines within the network. In the road network environment where the investment subject is diversified, the path identification not only involves how to calculate the toll for each passing vehicle, but also considers the problem of splitting the toll of the income to which charging unit, and the splitting of the toll is directly It is related to the legitimate interests of various highways.
In order to solve the above problems, a license plate identifier is installed in all the toll gates and exit lanes of the toll road network; a gantry-type license plate recognition system is installed at a key point of the ambiguous path. The system maximizes the role of license plate recognition, provides professional and practical management decision-making and service information for path identification, and greatly improves the charging efficiency and supervision level.
Third, highway over-limit treatment
1. Over-limit detection station rapid detection system
When a freight vehicle passes through a highway super-station, it often causes traffic jams due to the complicated inspection process. Most of the highway super-test stations also use manual input and recording methods. On average, it takes 2-3 minutes for each freight vehicle to be detected. Some traffic jams with large traffic flow often cause traffic jams.
After the automatic license plate recognition system is installed, the license plate number and load capacity of the detected vehicle will be automatically input to the computer, eliminating the need for manual recording. It takes only 10 seconds for each truck to be inspected, which greatly saves money. Detection time increases work efficiency and transparency of law enforcement.
2, high speed pre-check weighing system
On the highway with large traffic volume, many lanes and fast speed, a high-speed pre-check weighing system is installed to carry out weight pre-test on the cargo vehicles that are driving normally on the roadway. If the vehicle exceeds the limit value set by the system, then The vehicle license plate number and vehicle image, test data, etc. are transmitted to the front over-treatment overloaded law enforcement station; and the high-speed pre-check system pre-tests, the vehicle that meets the requirements is normal driving, and does not need to enter the law enforcement station.
The high-low speed combined with the dynamic weighing system is a good solution for over-limit overloading on highways with large traffic volume, many lanes and fast speed. It has the characteristics of high detection efficiency and strong detection, which reduces the The detection pressure of low-speed weighing in the law enforcement station ensures that road traffic will not cause congestion due to law enforcement testing.
Fourth, other
1. Parking lot, unit entrance and exit vehicle management
How to ensure the safety of vehicle parking is a problem that has been plaguing parking lot managers. The current solution is to enter the card and check out. The check of the card is carried out in two aspects. The identity verification of the card is performed by the computer, and the verification of the conformity of the person and the car is performed by the security guard. It is identified and handled by people's memory and responsibility. The problem is that since people's memory and sense of responsibility vary from person to person, whether or not they make mistakes in actual work will vary from person to person, and each new person must be retrained.
The above problem can be solved by installing a license plate identifier in the entrance and exit lanes. Automatic identification of license plate information; automatically establish one-to-one correspondence between license plate and identity card. When the vehicle is on the scene, the system will automatically check to prevent people without entry from entering the market and those with admission to drive other people's cars to play; In the vehicle database, only the vehicles in the free vehicle database can be released free of charge; the blacklisted vehicle database is established. When the blacklisted vehicle passes the exit, the system will automatically alarm and prompt the relevant processing.
2. Vehicle inspection line of vehicle management office
The auto detection system of the motor vehicle is equipped with a license plate recognition system, which further improves the automation degree, significantly shortens the total inspection time, reduces the queue length of the vehicles to be inspected, and obtains obvious social and economic benefits.
Four major applications of license plate recognition technology
1. The use of license plate recognition technology will greatly reduce traffic violations and accidents, and provide strong evidence for various traffic accidents and post-processing of life and property safety. It plays an important role in China's traffic safety and other aspects. Regardless of the triggering method, a mature license plate recognition system can effectively realize real-time monitoring and analysis of passing vehicles, and obtain various information such as license plate number, license plate color, vehicle type, etc., which is effective for combating theft and black. Strong support is provided for the list of motor vehicles, traffic accidents, escape vehicles, analysis of traffic conditions, and strengthening of public security management.
2. Intelligent transportation system based on license plate recognition can prevent motor vehicles from being stolen, stolen, fake cards, decks, smuggling, black market transactions and other increasingly criminal activities. Through the "electronic license plate" information registered by the motor vehicle, the monitoring center can effectively remotely control the image, digital information and direction of the suspicious vehicle, and feed back the traced information back to the monitoring center. * The department can timely understand, track, and control criminal activities such as illegal vehicle transactions and vehicle theft according to this information. For fake cards and deck vehicles, the detection and identification system sends an alarm message when the electronic license plate number does not match the external license plate during the detection process, so that the department can track down.
3. The intelligent traffic management system based on license plate recognition can provide accurate and detailed classification traffic statistics for urban road planning and design, realize the optimal design of road planning management, and reduce traffic congestion black holes. The intelligent traffic management system can sample vehicle traffic data at major road intersections in the city, and analyze data on vehicle categories (such as buses, trucks, buses, cars, taxis, etc.) and traffic to provide traffic flow for road planning and design. Accurate data such as vehicle categories, peak periods and high peaks, scientifically guide road planning.
4. The intelligent traffic management system based on license plate recognition can better solve the various "difficult problems" in current traffic management.
Application of new technology in license plate recognition system
1. High-performance embedded processing system
In the traditional high-definition system, the system sends the picture taken by the camera to the processing system such as the industrial computer for identification processing and storage, so that the requirements for the transmission and processing equipment are very high, and it is difficult to meet the design and processing capability requirements of the system.
The new intelligent HD camera embedded processing solution can effectively solve the above problems. Each lane is equipped with a 2 megapixel intelligent high-definition camera with a resolution of up to 1600×1200 pixels. It is responsible for the facial feature capture of the front passengers, the automatic identification of the license plate and the automatic recognition of the body color, and the processing results are passed through the ether. The network is sent to the intelligent HD camera terminal server.
The terminal server adopts the embedded linux special system, which is responsible for receiving, storing and uploading vehicle traffic information. At the same time, the user can view and manage all front-end devices through the terminal server. Each intelligent high-definition camera terminal server can simultaneously connect up to 20 intelligent high-definition cameras. Greatly improve system processing performance.
2. Integrated design of image acquisition and processing
The intelligent high-definition camera integrates industrial-grade progressive scan CCD and high-speed DSP chip, and independently completes the functions of image capture, license plate recognition, body color recognition, and vehicle speed acquisition. After the vehicle information is acquired, the result assembly and communication module are packaged and uploaded via Ethernet. The terminal server enhances the processing power of the system, making the system structure clear and concise, and easy to expand.
3, feedback control of all-weather high-definition imaging
The entire imaging system is a sophisticated system of intelligent high-definition cameras, intelligent fill light and imaging control software. The orderly coordination and feedback control between them makes the image of the vehicle captured during day and night high, ensuring the body, license plate and The facial features of the front passengers of the vehicle are clearly distinguishable.
The system integrates the reflection characteristics of the front windshield of the vehicle, the film condition, and the ambient light exposure. It adopts a special lens, a special imaging control strategy and a fill light method, and arranges a reasonable equipment layout method to make the system all-weather. For all types of vehicles, it can effectively solve the problems of front windshield reflection and direct light, to ensure that the facial features of the body, license plate and vehicle front passengers are clearly distinguishable.
4, body color recognition
It can automatically identify the color of the car body and the 10 common body colors, providing a new technology for the inspection of *inspection and criminal investigation cases.
The system automatically distinguishes between vehicles that are dark or light; and identifies 10 common body colors, including white, silver, gray (including ash and silver), black, red (with red and dark red), and dark blue. , blue (including blue and blue), * (including golden and yellow), green (including green and dark green), brown (including light brown and brown), colors other than 10 colors (including color vehicles) belong to other colors .
The accuracy of classification in shallow and shallow is not less than 80%; the accuracy of recognition of 10 common body colors is not less than 60%.
5, video assisted trigger, auxiliary speed measurement
Video triggering is used as an auxiliary trigger. In the case of coil trigger failure, it can alarm in a short time and replace the coil for triggering. In this way, the user can obtain the fault information at the first time, and can still effectively monitor the road running condition before the problem is solved, and can achieve uninterrupted monitoring and timely response.
6, front-end, back-end independent proprietary network structure
Two independent network structures are used, that is, the network between the terminal server and the intelligent high-definition camera and the network between the terminal server and the center are independent of each other. This can reduce the occupation of the IP address of the * network, the device increase or IP change in the monitoring point is more convenient, and the network security is greatly improved.
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