Research on the design of a full-function electronic police system

With the rapid development of urban modernization, the number of motor vehicles in Tianjin has shown a rapid growth trend. In the city's road traffic, illegal speeding, large trucks driving on the road during prohibited hours, and blacklisted vehicles such as duplicate license plate vehicles driving on the road are common. Detecting various types of illegal incidents is an important task for public security organs to maintain traffic order.

The current road traffic situation is becoming increasingly complex, traffic events are diversified, and the traffic management department's demand for information is increasing, making the system structure design more and more complex and the equipment more and more. In some important traffic sections and intersections, there are often several or even dozens of cameras working at the same time, which not only affects the road traffic landscape, but also causes psychological pressure on travelers.

From a technical perspective, the more equipment a system has, the lower its efficiency and the higher its failure rate, which means more maintenance manpower and maintenance costs. At the same time, repetitive municipal construction in terms of pole foundations and power supply not only increases investment but also affects the urban landscape.

Therefore, researching full-function electronic police equipment can not only optimize the system structure, but also fully tap the potential of system hardware resources and maximize economic benefits using limited funds.

With the rapid development of urban road network construction, the construction of independent subsystems is no longer suitable for future development trends. The core task of this full-function electronic police system R&D project is to establish a multi-service, multi-task integrated system, streamline front-end equipment, unify transmission routing, and unify management platform.

In general, the full-function electronic police system studied in this paper has the following characteristics compared with the current general traffic detection system:

1) It has comprehensive traffic detection functions, covering seven major functions: license plate recognition, traffic flow data detection, accurate vehicle type distinction, unlicensed vehicle capture alarm, vehicle speeding violation detection record, blacklist comparison alarm and real-time monitoring.

2) It has a wide field of view, which can not only provide full-scene monitoring and detection, but also meet the requirements of illegal evidence collection and high-precision license plate recognition.

3) Provides a laser contact signal with the same characteristics as the toroidal coil detector, which can detect vehicles in the target lane with extremely high accuracy, achieving a 99% capture rate, which is not available in traditional video detection systems.

4) The system design is consistent with the existing system of the traffic control command center in terms of software and hardware configuration, underlying data format, communication interface and transmission, so the interface is convenient and the compatibility is good.

5) Since a set of multifunctional detection equipment is used to realize functions that previously required multiple different systems to complete separately, the cost of the entire system is greatly reduced and the overall stability of the system is also improved.

6) We have completely domestically produced independent intellectual property rights in image adaptive control acquisition technology and high-precision license plate recognition technology, and these technical indicators are in a leading position internationally.

7) It has complete system operation status monitoring and automatic fault detection and alarm functions, making the system easy to maintain.

1. Design ideas of fully intelligent electronic police system

1.1 Accurately identify trucks

The ultrasonic traffic detector is not affected by light or climate and can identify 9 types of vehicles, including passenger and freight vehicles. All indicators meet or exceed national standards. It is an ultrasonic detector with stable quality and reliable performance, and has the following characteristics:

● It can detect traffic volume, vehicle type, speed, occupancy time, headway and traffic jam time more accurately.

● Finer vehicle type distinction. The ultrasonic traffic flow detector has a higher resolution for vehicle types and can identify 9 types of vehicle types, including passenger and freight vehicles. They are: small passenger cars, medium-sized passenger cars, large buses, small trucks, medium-sized trucks, large trucks, extra-large trucks, containers, and trailers. The comprehensive recognition rate is ≥93%.

● The binary data transmission format is adopted, which greatly reduces the data transmission volume compared with the original ASCII code data format, improves the reliability of data transmission and occupies less communication resources, and is more suitable for the needs of multi-point and wireless transmission.

● The single-probe detection method can maintain the detection accuracy of the original dual-probe detection method, and because one probe is reduced, it makes installation easier, operation more reliable, installation costs lower, and reduces the impact on the urban landscape.

1.2 Realize the application of high-definition video technology

With the development of intelligent transportation technology and the widespread application of video detection technology, "images" as the largest and most intuitive information source play a pivotal role in the comprehensive traffic monitoring system. The quality of images directly affects the capabilities and operating efficiency of the entire system.

At present, the total CCD pixel of the cameras used in the traffic monitoring system is only about 400,000 pixels. For some occasions that require higher pixel quality, such as: roads or intersections with large traffic volume and complex traffic environment, the camera is required to monitor a large range and see the detailed features of the vehicle in the video playback. The 400,000-pixel image is obviously not enough for such image processing. At the same time, most COMS high-definition cameras have poor night sensitivity and will produce deformation when shooting high-speed moving vehicles, which cannot meet the all-weather needs of electronic police.

The emergence of ultra-large CCD high-definition cameras has greatly improved the resolution of camera images, making the details of the images clearer and more delicate. High pixels mean a large amount of information, and every detail can be seen at a glance. Details such as license plates that cannot be clearly identified by ordinary cameras are now clearly visible.

In the full-function electronic police system, the use of a 2-megapixel high-definition video camera with an ultra-large target area CCD and the application of high-definition video technology to the field of electronic police are undoubtedly a technological innovation.

1.3 Realize the capture of vehicles without rear license plates

As the number of electronic police systems increases day by day, and most of them take photos of the rear of the car, many car owners choose not to hang or intentionally cover the rear license plate in order to evade punishment. This system aims at this illegal behavior and realizes the function of capturing the rear license plate without adding a small amount of equipment.

2. System design highlights

2.1 The most advanced front-end core technology of traffic violation monitoring system:

The "LiDAR" synchronization method refers to the use of short-range ranging laser triggering plus radar speed measurement, which utilizes the inherent advantages of the physical working principles of the two devices: the short-range ranging laser is extremely accurate in triggering vehicles and will not be interfered with, while the narrow-wave speed measurement radar has extremely high speed measurement accuracy due to the Doppler effect.

At the same time, laser triggering can accurately guide the ultrasonic detector to the vehicle to be detected, so that the ultrasonic detector can accurately determine the model of the target vehicle.

2.2 Advanced motion analysis and determination calculation:

Since we need to capture a vehicle without a rear license plate or one with a rear license plate blocked, we need to accurately determine that it is the only target vehicle, so we need to analyze and determine the target vehicle's motion trajectory, and the calculation speed needs to be extremely fast, because a vehicle with a speed of 90 km/h moves 25 meters per second, and in a shooting area of ​​less than 10 meters, the time left for calculation and judgment is less than 400 milliseconds, so the calculation and judgment are quite difficult. Therefore, the DPS embedded algorithm supported by hardware is used.

3. System function design

HD integrated acquisition processing unit (ZHST-HD-10K) can be configured into integrated processing units with different functions according to different configurations. These processing units include: red light running monitoring integrated processing unit, speeding monitoring integrated processing unit. HD integrated acquisition processing unit (ZHST-HD-10K) gives the following important functions to the traffic violation integrated monitoring system.

3.1 Automatic license plate recognition function

● The system can automatically identify license plates in close-up images, including:

License Type:

(1) Type 02 personalized license plate (GA36.1-2001);

(2) The current Type 92 license plate (GA36-92);

(3) Military vehicle license plate;

(4) Police car license plate;

(5) Armed Police Vehicle License Plate (new style);

(6) Agricultural vehicle license plate;

In the absence of fog, the license plate is hung and placed in the correct position and without any damage, and there are no five small vehicles, the system's license plate recognition rate should meet the requirements of GA497.

● Vehicle type and color recognition function

The system can distinguish between large and small vehicles and recognize the five common license plate colors: red, white, blue, yellow and black.

3.2 Automatic alarm function

● Overspeed alarm

1) Capture images of all vehicles passing through the monitored lanes and automatically identify their license plate numbers. Image information includes: host number, specific location, specific lane, driving direction, vehicle type, license plate color, license plate number, image sequence number, etc.

2) The vehicle image capture rate is greater than 99%, and the all-day recognition rate is >95%.

3) The system uses narrow beam radar detection, which can accurately calculate the vehicle speed and determine whether it is speeding, with a speed measurement error of -2%;

4) When a speeding violation occurs, capture a panoramic picture and a close-up picture to form a picture. The picture should clearly identify the road section information, vehicle direction, speed limit sign, license plate number, license plate color, vehicle body color, and vehicle model;

5) The image format should be JPEG according to the standards of the Ministry of Public Security;

6) Image information includes: host number, violation location, violation lane, vehicle speed, driving direction, violation time, violation type, license plate number, image serial number, etc.

7) The images have a modification prevention function to ensure the originality of the illegal images;

8) It can collect traffic information at intersections, including traffic volume, average speed, average vehicle distance, occupancy rate, etc., and has traffic detection and statistical functions.

9) The system is scalable, portable and compatible, and provides open interfaces;

10) Panoramic continuous real-time video recording, the video file format is H.264. It can be transmitted in real time over the network to provide video monitoring for the backend;

11) Parameters that can be set include: specific speed limit, video data storage time, image data storage time, data storage format, data storage size, traffic information collection cycle, etc.;

12) Using radar speed measurement, each lane uses a narrow-wave radar to ensure its unique accuracy. The maximum speed of the vehicle that can be captured is: 230 km/h;

13) Speed ​​limit calibration can be set.

● Monitoring, investigation and vehicle alarm

Each monitoring point needs to have a separate control and query database, and the control database is built separately according to the categories of accident vehicles, stolen vehicles, etc. At the same time, each monitoring point can automatically download control information such as suspected vehicles from the management center, and support the management center to remotely modify, add, and delete the control and query database in each customer's monitoring point. The control and query of vehicle license plates can be set up, and when the vehicle license plate results identified by the system meet the conditions, remote alarm or on-site alarm can be issued.

3.3 Information upload and download functions

Provides automatic upload of all vehicle information passing through the monitored road section, including information and pictures of illegal vehicles. Other pictures and basic information are stored in the HD comprehensive acquisition and processing unit (ZHST-HD-10K), but the function of uploading pictures and related information can be provided when necessary. If the alarm information is stored in the HD comprehensive acquisition and processing unit (ZHST-HD-10K), it includes manual or automatic download functions of stolen vehicles, suspicious vehicles, specific vehicles and other information. It has the functions of network data transmission and on-site data download.

There are two ways of network data transmission: real-time transmission and non-real-time transmission. You can choose any one of them. Supports various transmission methods including optical fiber, ADSL, etc. When a network failure occurs during the transmission process, it has the function of breakpoint resumption (not only restoring the function of real-time transmission of illegal data and pictures, but also automatically retransmitting illegal pictures and data that were not transmitted due to network failure when idle).

Support data download: the data center "blacklist" and other information can be downloaded to the HD integrated acquisition and processing unit (ZHST-HD-10K).

3.4 Data storage function

The HD integrated acquisition processing unit (ZHST-HD-10K) has 500G storage space and can store 1 million vehicles. When the number of vehicles exceeds 1 million, the front image data will be automatically overwritten in sequence. The HD integrated acquisition processing unit (ZHST-HD-10K) always retains at least 1 million vehicle images. It also has time, speed, location and direction information.

The HD integrated acquisition and processing unit (ZHST-HD-10K) can store panoramic camera videos for 30 days. The video file format is H.264. When more than 30 days have passed, the most advanced videos will be automatically overwritten. The HD integrated acquisition and processing unit (ZHST-HD-10K) always retains at least 30 days of video.

3.5 Statistical query function

To meet the needs of traffic management, the traffic conditions in each time period, such as vehicle volume, vehicle type and average speed, are counted for each lane or multiple lanes according to user requirements (users can set the time period and select several lanes to be counted, such as certain lanes within an hour, a day or a week). These data are stored in a separate database as the data basis for traffic status detection and traffic statistical analysis. For a certain time period, the number of vehicles passing through certain lanes N times can be counted (N is the number set by the user, and the user can select one or more lanes).

For each vehicle passing through the monitored road section, the system can record the passing time, license plate number, vehicle model, vehicle type, vehicle picture, etc. in the database. The front-end system provides an interface for querying and accessing data, through which the control center can access the front-end stored data.

3.6 Automatic remote management function

The HD integrated acquisition processing unit (ZHST-HD-10K) can automatically download system parameters from the management center, such as: information on changes in the control library, speed limits, system time, blacklists, etc., and automatically synchronize time based on the central server every day. It has a remote equipment maintenance function.

3.7 Automatic fault detection and recovery function

The HD integrated acquisition and processing unit (ZHST-HD-10K) can automatically detect the working status of the main equipment at regular intervals, and report the operating status of the equipment when uploading data, so that the central computer room can grasp the working status of the lane equipment in a timely manner. The HD integrated acquisition and processing unit (ZHST-HD-10K) is equipped with a hardware watchdog. If the system crashes due to an accident, the watchdog will play a role and automatically reboot the system to enter the working state.

3.8 Other basic functions

● Real-time video playback: Real-time video function: supports real-time high-definition panoramic video recording, 25 frames per second, compression format is H.264, 720P;

● IP multicast streaming media playback mode: can send real-time continuous video streams to multiple clients simultaneously without delay for users' digital monitoring;

● Data upload: Built-in data distribution upload program can upload specified data to the specified application system.

The automatic fault detection and automatic recovery function can automatically detect the integrated unit fault and automatically recover and restart due to unexpected freeze.

This paper studies a full-function electronic police device with comprehensive traffic detection functions, covering license plate recognition, traffic flow data detection, accurate vehicle type distinction, unlicensed vehicle capture alarm, vehicle speeding violation detection record, blacklist comparison alarm and real-time monitoring. It is hoped that in the context of the increasingly complex current road traffic conditions, the potential of system hardware resources can be fully tapped and the functions of intelligent traffic management equipment can be integrated, thereby improving the scientific and technological level of road traffic management in Tianjin.