Application case of automatic license plate recognition equipment in parking lot system management
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Based on the combination of the CASTLE parking lot system and the license plate recognition system, the anti-cheating management of the in and out weighing of transportation vehicles such as factories and mining is realized. The weighing flow scale can be completed quickly, accurately, safely, stably and reliably without human intervention, and the fully automated management of information collection in the measurement process can be realized. Intelligent management of internal and external vehicles in the factory, clear analysis and display of vehicle weighing status, whether it is purchased or shipped, to prevent the production of factory goods when the vehicle is shipped or the shortage of goods when entering the factory, and fully protect the interests of the factory and the country The property will not be lost.
1. Overview of License Plate Recognition
The vehicle license plate is the only mark for vehicle identification in the world. Its particularity and importance determine that the license plate recognition system becomes an indispensable and important part of the urban intelligent traffic management system. The license plate recognition system provides an efficient and practical means for automated intelligent traffic management.
The main functions of the license plate recognition system in the current market include:
1. Automatic recognition of vehicle license plates, the information includes complete license plate information, colors, characters, Chinese characters, and numbers.
2. Automatic detection of vehicle speed.
3. Recognition and alarm of illegal vehicles with black license.
4. Linkage control of vehicle identification information and vehicle information of the vehicle management station
5. Judging and monitoring the driving direction of the vehicle
The main application areas of license plate recognition systems in the current market include:
1. Intelligent traffic management at traffic intersections
2. Automatic collection of traffic information
3. The police and other law enforcement agencies set up temporary inspection stations to conduct inspections on passing vehicles and prioritize the identification of vehicles to be inspected;
4. Automatic toll collection system for roads, bridges, tunnels, etc.
5. Automobile entrance and exit management of modern residential districts, parking lots, and important institutions
6. Snapshot recognition of road security bayonet, traffic flow monitoring
The pros and cons of the license plate recognition system are mainly determined by two key performance parameters: recognition rate and recognition speed.
1. Recognition rate
Whether the license plate recognition system is practical or not, the most important indicator is the recognition rate. The internationally recognized recognition rate index requires that the correct recognition rate of all cards is 85% to 95% 24 hours a day. The recognition rate statistics are also divided into the following three methods:
a. Natural traffic recognition rate = the total number of recognized license plate numbers / the total number of vehicles actually passed
b. Recognizable license plate rate = total number of license plate numbers correctly read manually / total number of vehicles actually passed
c. Accuracy rate of full license recognition = the total number of license plates correctly recognized by the full license/the total number of license plates read by manual recognition
These three indicators determine the recognition rate of the license plate recognition system.
2. Recognition speed
The recognition speed determines whether the license plate recognition system can meet the requirements of real-time practical applications. A system with a high recognition rate, if it takes a few seconds or even a few minutes to recognize the result, the system will be meaningless because it cannot meet the real-time requirements in practical applications. The recognition speed proposed by international traffic technology is within 1 second, the faster the better. At present, the recognition speed of the license plate recognition system in the market is 200 milliseconds on average in actual application. A good license plate recognition system has reached a fast recognition time of 10 milliseconds, and the actual application recognition speed can reach an average of 40 milliseconds.
Second, the realization principle and realization method of recognition technology
The recognition of vehicle license plates is based on the theory of image segmentation and image recognition. It analyzes and processes the image containing vehicle license plates to determine the position of the license plate in the image, and further extract and recognize text characters.
The recognition steps are summarized as: license plate location, license plate extraction, and character recognition. The three-step recognition work complements each other, and each has a higher efficiency, and the overall recognition rate will increase. The speed of recognition depends on the character recognition. The current main application technology for character recognition is the comparison and recognition sample library, which is to establish a sample library for all characters. After the characters are extracted, the character judgment will be realized through the comparison sample library, which will be generated during the recognition process. Intermediate result values such as credibility and slope; the other is character recognition technology based on the knowledge of character structure, which more effectively improves the recognition rate and accuracy, and has strong adaptability.
There are two main ways to realize the license plate recognition system: one is the recognition of static images and the other is the real-time recognition of dynamic video streams. The recognition efficiency of static image recognition technology is largely limited by the image capture quality. It is a single frame image recognition. The current market product recognition speed is an average of 200 milliseconds; while the dynamic video stream recognition technology has strong adaptability and recognition speed. Fast, it realizes the recognition of each frame of the video, increases the number of recognition comparisons, and chooses the preferred license plate number. The key is that it is less affected by the quality of a single frame. The current market product recognition takes 10 milliseconds.
3. Application of License Plate Recognition in Public Security Checkpoint System
The license plate recognition system has been maturely used in various intelligent transportation and security systems to automatically detect and recognize vehicle license plates in images and videos. Typical application systems are: red light automatic monitoring system, motor vehicle speeding monitoring system, Intelligent transportation systems such as motor vehicle retrograde and line pressure monitoring systems, mobile electronic police systems, and security checkpoint systems.
A more typical application is the security bayonet system (scientific name: Highway Vehicle Intelligent Monitoring and Recording System). If the system does not have license plate recognition technology, there is no real automation intelligence. A complete security checkpoint management system should have three main functions: automatic license plate recognition, checkpoint application system and central network management. License plate recognition is the most important part. Only a bayonet system that achieves rapid and practical recognition technical indicators can effectively achieve automatic comparison and alarm, and avoid a large number of false alarms. At the same time, the recognition speed is fast, the system needs to occupy less system resources, the possibility of manual intervention is small, and the operating burden of the system network is correspondingly reduced. The quality of license plate recognition directly affects the overall performance of the bayonet system.
Baoer’an security bayonet system has given full play to the advantages of license plate recognition technology and distributed architecture design to build an efficient and unified bayonet system platform. It has comprehensive business functions such as car image recording, speed measurement, number plate recognition, automatic alarm, data management, traffic statistics, remote maintenance, etc. It has been widely used in the prevention of traffic accidents on national highways, provincial highways, expressways, etc. And the detection of related vehicle cases. The operation of the entire system revolves around the core of the license plate number, and the high efficiency of the license plate number recognition directly affects the overall performance of the system. Therefore, the front-end design of the system adopts the real-time recognition technology of video stream, and the recognition time of 10ms fully guarantees the one-by-one recognition of high-traffic road vehicles, reaching the international index that the all-weather full-plate recognition rate is not less than 85-95%.
The number of application channels: single channel or multi-channel, the weighbridge on each channel can be managed by two-way overbalance weighing, single machine management or networked multiple computers.
Fixed vehicle weighing principle: This part of the vehicle is mainly aimed at the fixed vehicle or internal vehicle management that often enters and exits the factory, using the principle of long-distance reading and writing system, mainly Bluetooth long-distance card reading application system.
When entering, do not stop and overbalance. After reading the vehicle information through the remote reading and writing system, the license plate capture system captures the license plate number and the vehicle information in the system allows overbalance weighing. After weighing, voice broadcasts the body weight.
The vehicle information is read out through the remote reading and writing system when it is exported. The license plate capture system captures the license plate number and the vehicle information in the system allows for overbalance weighing. After weighing, the voice broadcasts whether the goods are purchased or shipped. The weight of the shipment is reported when the shipment is shipped, and the weight of the purchase is reported for the purchase.
Remarks: Shipment weight = the weight of the body at the time of delivery is the weight of the pulled cargo-the weight of the body when entering, the weight of the purchase = the weight of the body when entering-the weight of the body when it is exported is the weight of the pulled cargo, the soft can automatically identify whether it is a purchase or a shipment , And can record the attendance of vehicles entering and exiting, how many times the vehicle passed, the weight of the vehicle each time it passed, whether it was shipped or purchased, inbound data analysis and export data, clear analysis and display of vehicle in and out weight information, convenient for the attendance of incoming and outgoing vehicles.
The principle of temporary foreign vehicle management: It mainly adopts short-distance reading and writing technology, automatic card collection and issuance. When the vehicle enters, the license plate recognition system captures the license plate number after the card is taken, records the license plate number, and the system displays it as a temporary vehicle and records the license plate number. The weight of the vehicle body under the license plate number, and the weight of the voice broadcast. At the time of delivery, after weighing, the temporary card will be retrieved by the automatic card collector. The image capture system will automatically capture the license plate, and the gate can be opened only if it is consistent with the imported information, and the weight of the purchase or shipment will be broadcast. With the advancement of technology and the development of image vision technology, the future license plate recognition technology will be more intelligent.
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