The scheme of city electronic police automatic identification system based on RFID technology
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Demand analysis
With the rapid economic development, the number of urban cars is increasing, and the number of car drivers is also increasing. At the same time, there are more and more vehicle violations that accompany it, causing a lot of economic and personal damage. Civilized cities, maintaining traffic order and protecting personal safety have brought many obstacles. How to effectively solve traffic congestion and various traffic violations, reduce the occurrence of traffic accidents, and meet the requirements of unblocked projects, is becoming an important issue urgently needed to be resolved by urban traffic management departments.
“Electronic police” is also known as the vehicle recording system for breaking red lights. Red light running illegally is one of the main causes of traffic accidents, traffic chaos, and traffic jams. The electronic police system monitors red light running at traffic intersections for 24 hours. Once a vehicle runs red light illegally, it is immediately captured as a basis for punishment.
At present, in the field of electronic police running red lights, there are two main ways to detect vehicle passing: coil detection and video detection. There are mainly two types of capture methods: digital cameras and camcorders. The detection accuracy of the coil type vehicle detector can meet the needs of customers, but the road surface needs to be cut. The advantage of video vehicle detection is that there is no need to cut the road surface, but the detection accuracy is low. Generally, the detection accuracy can exceed 50% during the day, and between 30%-50% at night. As far as our analysis is concerned, the reason why such products are widely used successfully abroad is that the road conditions are simple, and there are few mixed traffic of motor vehicles, non-motor vehicles and pedestrians. In China, video detection products should be applicable to traffic information collection systems on expressways, but such complex application conditions at intersections are still inappropriate.
application solution
Shanghai Boao Electronic Technology Co., Ltd. combines RFID and wireless sensing technology to develop a wireless embedded vehicle detector for accurately detecting vehicle passing.
The three elements of a red light snapped picture: stop line, red light signal, and license plate number.
According to the principle of electromagnetic induction, when a metal object passes through an electromagnetic field, the magnetic flux of the electromagnetic field will change, which will cause a change in the return circuit of the electromagnetic field. A wireless geomagnetic detector is buried outside the parking line at the intersection. The wireless geomagnetic detector will generate an electromagnetic field perpendicular to the road surface. When a vehicle passes by the wireless geomagnetic detector, it is equivalent to a metal object cutting the electromagnetic field, so the magnetic flux of the magnetic field A change occurs and causes a change in the loop current of the wireless geomagnetic detector. After the vehicle detector installed at the intersection receives the return circuit of the wireless geomagnetic detector, it converts the current signal into a high and low frequency output signal. On the other hand, the signal light converter installed at the intersection simultaneously receives the current signal of the signal light, and converts the current signal of the signal light into a high and low frequency output signal. If the control software installed on the intersection industrial computer detects both the “red light” signal of the signal converter and the vehicle detector signal that the vehicle is passing by, it will send a capture signal to the camera and flash, and the camera will receive the photo. After the signal, it will automatically take pictures of the violation of the vehicle crossing the parking line in the “red light” state. If the ambient light at the intersection is insufficient, the control system will automatically activate the flash to fill up the light. The captured violation information includes “stop line, red light signal, license plate number, vehicle type, body color, violation date and time, violation lane” and so on.
The control software of the system must simultaneously detect the “red light” signal of the signal converter and the signal of the vehicle passing by the vehicle detector before it can transmit a capture signal to the camera and flashlight. These two detection signals are indispensable. For example, if the traffic signal at an intersection is a green light signal, the signal light detector detects a “green light” signal. Although the vehicle detector detects a signal that a vehicle is passing by, the control signal will not send a capture signal to the camera and flashlight. If the signal lights at the intersection are controlled by multiple phases, which are divided into left-turn, straight-go, and right-turn signals, detection coils can be embedded in different lanes to detect each lane to prevent missed shots and false shots in different lanes. Conducive to the fairness and accuracy of law enforcement.
Program features
•High precision: The earth’s magnetic field is basically constant within a few kilometers, but large ferromagnetic objects will cause huge disturbances to the earth’s magnetic field. The geomagnetic sensor can distinguish 1/6000 changes in the earth’s magnetic field. The influence on the geomagnetism when passing will reach a fraction of the intensity of the geomagnetism, so the use of geomagnetic sensors to detect vehicles has extremely high sensitivity.
• Convenient installation and maintenance, no need to close the driveway, less damage to the road surface, no need to damage the road surface when installing the hanger or side at the detection point, and only need to check the geomagnetic sensor during maintenance. The detection point is not easy to be damaged and is not affected by road movement.
•The geomagnetic sensor uses the change of the earth’s magnetic field when ferromagnetic objects pass through to detect, so it is not affected by the climate
• Two-way high-speed data exchange can be realized between the detector and the receiver.
•High reliability, working temperature -40℃~85℃, waterproof and shockproof.
• High anti-interference: There are no special requirements for various interference sources on site, and the installation is convenient and simple.
• There is no need to apply for and pay for the ISM microwave frequency band that is open worldwide.
•Ultra-low power consumption: safer and healthier for the human body.
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