Highway toll ambiguity path solution based on high-definition license plate recognition system
chrispeng [ad_1]
0 background
With the rapid development of expressway construction, expressways in many provinces in China have gradually developed into a network structure. There is more than one path from the same point to another point. Expressway construction and management have begun to pay attention to the problem of expressway ambiguity. Identification has become an urgent problem to be solved. The ambiguity of expressway path recognition has received social attention, and it has something to do with expressway development, traffic management needs, improving service levels, and toll splitting.
The network development of expressways and the complex composition of investment entities in each section are the fundamental reasons for the demand for ambiguous path identification. Due to the different investment entities of each road section, they are more sensitive to the problem of inaccurate splitting due to ambiguity paths. In order to protect the legitimate rights and interests of each investment entity, it is necessary to adopt technical means to improve the accuracy of ambiguity path identification and solve the cost splitting. Vague question.
At present, the main idea of solving the route recognition problem in China is to try to accurately identify the route of the vehicle on the spot through technical measures, and directly solve the problem of tolling and splitting. Technical measures usually include: station identification method, license plate identification method, label identification method, RFID radio frequency identification method, etc. This article mainly combines the author’s participation in the design work of a domestic province’s path recognition solution, and elaborates the path recognition solution based on high-definition license plate recognition, including the principle of the license plate recognition solution, technical implementation plans, main equipment requirements, and path construction implementation.
1 Principles of the license plate recognition solution
The basic idea of identification is to identify the actual driving path of each vehicle in the road network, avoiding the ambiguity of the driving path in the road network, so as to solve the multi-path problem in the road network. The basic principle of identifying the driving path of the vehicle through the identification method is to collect the information of the driving path of the vehicle through some means to confirm the driving path of the vehicle. The driving route information of the vehicle mainly includes three kinds of information such as exit, entrance, road section, etc. As long as the three kinds of information are complete, the route can be uniquely determined.
The core of the license plate recognition method is to use the unique characteristics of the license plate of the vehicle driving on the highway, relying on the automatic license plate recognition technology and the good application of the network real-time transmission technology, and install the license plate recognition system (or manual input) at the entrance and exit of all highways. License plate), set up the mainline license plate automatic recognition system at key points in the road network, and upload the recognized license plate information of the passing vehicle to the upper-level system; at the exit of the vehicle, the system queries the license plate record of the vehicle passing the key point on the way, and the entrance, The three types of license plate information of exits and road sections are compared, the actual route of the vehicle is determined, and the vehicle toll is collected, and this is used as the basis for split toll settlement.
The specific implementation is to set up a mast on the path section between two points of an ambiguous path in the expressway network, install a license plate recognition device on the mast, and deploy cameras in combination with the actual number of lanes, and the license plate recognizer automatically recognizes passing vehicles The license plate number, the license plate recognition management software collects the recognition results (time, site and license plate number, etc.) and pictures of each license plate recognizer in real time and saves them on the local server. The transmission software uploads the recognition results to the provincial networking center, and the charging software is based on the license plate. The recognition result information calculates the fee amount.
2 Technical implementation plan
2.1 System composition
A gantry is installed at a suitable position in the main line section, and a 3 million pixel license plate recognition device is installed on the gantry. A total of 4 cameras are used for two-way four to six lanes. Two cameras are installed in each direction to work in hot standby mode and arranged on the gantry. In addition, in order to improve the recognition accuracy and night driving comfort, a set of metal halide lights was installed on the gantry of the camera, and another set of gantry was installed 25 meters in front of the gantry, and a set of metal halide lights/lane was installed on the gantry. .
A set of equipment cabinets are installed on the roadside of the gantry, where switches, UPS, distribution boxes, lightning protection devices, etc. are placed. The front-end imaging equipment is mainly a camera, lens and fill light fixed in the shield. The high-definition license plate recognition processing equipment is installed in the remote toll station. The high-definition camera and the AC/DC module are installed in the shield, which is installed above the road surface, and the horizontal distance between the center point of the image and the gantry is 35 meters. Three high-brightness LED auxiliary light sources are installed around the high-definition camera with a horizontal spacing of 0.1 meters, respectively pointing to the area covered by the camera’s field of view of the three lanes.
The high-definition camera transmits JPEG image frames through a 100M network port, and the signal is transmitted to the nearby toll station through a switch + optical fiber. After the uploaded image frame data is processed by the high-definition license plate recognition processing equipment, the recognition result is saved to the background database server and transmitted through the communication system To the provincial center, the provincial center constructs route information according to the uploaded entrance and exit information and the recognized license plate information when the toll is settled.
At the same time, it is necessary to set up some auxiliary facilities including metal halide lamps, outdoor cabinets, distribution boxes, lightning protection devices, twisted pairs, single-mode optical cables, cables, etc. The solution uses dual-machine hot backup for each lane to improve the accuracy of the license plate information capture, thereby improving the recognition rate and stability of the license plate information.
2.2 Location selection of license plate recognition point
The location of the license plate recognition point mainly considers the following factors:
(1) Each section of each ring road has one location;
(2) Place the gantry on the road section as close as possible to the toll station or service area, so as to ensure the power supply and data transmission;
(3) The location of the gantry shall not exceed 3 lanes in one direction as far as possible to save investment costs;
(4) About 500m in front of the camera angle of view should be a straight line;
2.3 Design points
(1) Front-end gantry design
? Height 6.5 meters -8.5 meters;
? Reserve a crossbar that can be installed with front-end image acquisition equipment, the diameter of the crossbar is not less than 60 mm;
? Power, transmission on the shelf;
? Need lightning protection design.
(2) Front-end image acquisition
? Adopt 3 million pixel high-definition camera to achieve full coverage of 2~3 lanes;
? Use hoop to install on the crossbar of the gantry;
? The night fill light is installed on the same crossbar in a way of one channel and one set;
? Use Category 5 network cables to transmit data to the control cabinet near the gantry.
(3) Signal transmission
? A control chassis is set next to the gantry, and a switch and other equipment are set inside;
[ad_2]
