CN111311928A - Speed measuring system and speed measuring method of double geomagnetic sensors - Google Patents

Abstract

The invention discloses a speed measurement system and a speed measurement method based on dual geomagnetic sensors, which mainly solve the problems of high cost and complicated installation of the existing speed measurement system. The input and output ends of the data processing module are respectively connected with the dual geomagnetic sensor module and the data reporting module, and the data reporting module is wirelessly connected with the base station module; the two geomagnetic sensors A and B in the dual geomagnetic sensor module collect magnetic field data around them respectively, It is transmitted to the data processing module for storage, and based on the data to determine whether there is a vehicle passing through the detection range of the sensor, the vehicle speed is calculated and output to the data reporting module; the data reporting module sends the vehicle speed information to the base station, and the base station will receive each data The vehicle speed data sent by the reporting module is reported to the traffic data analysis platform. The system of the invention has low cost, convenient installation, is favorable for large-scale deployment, and can be used for road intelligence.

Description

Dual geomagnetic sensor speed measuring system and speed measuring method

technical field

The invention belongs to the technical field of intelligent transportation, and further relates to a speed measurement system of a geomagnetic sensor, which can be used to detect the vehicle speed of a motor vehicle to realize road intelligence.

Background technique

Transportation is the main driving force for urban development. The surge in car ownership has caused increasingly serious problems such as traffic congestion, traffic accidents and environmental pollution, which seriously restricts the development of urban social and economic development. Therefore, transportation reform is urgent. Road intelligence is the key to solving the above-mentioned traffic problems and supporting the sustainable development of cities. my country has listed intelligent networked vehicles as a national development strategy. As a key part of building a comprehensive perception of people, vehicles, roads and networks, smart highways will be combined with intelligent driving technology to strongly support autonomous driving applications and promote the construction of intelligent transportation. As an important part of smart highways, vehicle speed detection is widely used in intelligent assisted driving, intelligent monitoring, pedestrian analysis and other fields.

In the application of smart highways, motor vehicle speeding is one of the most serious road traffic violations and the main cause of road traffic accidents, causing huge losses to human life, health and property. Therefore, monitoring the speed of vehicles on the road to ensure that the speed of motor vehicles is within a safe range is of great significance for preventing and reducing traffic violations and accidents caused by motor vehicles speeding. The car speed measurement system is one of the most important devices to detect whether the vehicle is speeding or not. However, most of the current vehicle speed detection systems are relatively expensive and the deployment cost is high, which is not conducive to large-scale, full-coverage deployments. As a result, some vehicles continue to speed on roads without speed detection. Managed.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose a speed measurement system and speed measurement method based on a geomagnetic sensor to reduce the cost of speed measurement, facilitate installation and large-scale deployment, and realize all-round control of motor vehicles overspeed.

In order to achieve the above purpose, the speed measurement system based on the geomagnetic sensor of the present invention includes a data processing module, a data reporting module, a base station module, and a power supply module; the data reporting module is wiredly connected to the data processing module, and the data reporting module is wirelessly connected to the base station module. It is: the input end of the data processing module is connected with a dual geomagnetic sensor module, and the two geomagnetic sensors A and B in the dual geomagnetic sensor module respectively collect the magnetic field data around them, and transmit them to the data processing module to save them, and accordingly The data judges whether there is a vehicle passing through the detection range of the sensor, calculates the vehicle speed and outputs it to the data reporting module; the data reporting module sends the vehicle speed information to the base station module, and the base station module reports the vehicle speed data received by each data reporting module to the traffic Data analysis platform.

Further, the output end of the power supply module is connected to the data processing module, and the power supply mode of the input end of the power supply module may be all power supply modes such as solar energy, wind energy, and commercial power.

Further, the geomagnetic sensor includes: a digital geomagnetic sensor, an analog geomagnetic sensor, a single-axis geomagnetic sensor and a multi-axis sensor;

Further, the magnetic field data refers to the fluctuating magnetic field data detected by all geomagnetic sensors when a car passes by and the relatively stable magnetic field data when no car passes. The magnetic field fluctuation range does not exceed 20nT.

Further, the two sensors A and B are placed back and forth, and the car passes through the sensor A and the sensor B in sequence when driving.

In order to achieve the above-mentioned purpose, the present invention is based on the above-mentioned system to measure the method for speed, including the following:

1) In the system, two geomagnetic sensors A and B respectively collect the magnetic field data of the location of the sensor in real time, and transmit them to the data processing module in turn;

2) The data processing module parses the data transmitted by the two sensors:

2a) The data processing module determines whether the data mark of the first geomagnetic sensor A is a car: if so, it is determined that there is a car passing by, and 3b) is executed, otherwise, 1) is returned;

2b) The data processing module judges whether the data flag of the second geomagnetic sensor B is a car: if so, it is judged that a car passes by, and executes 3b), otherwise, returns to 1);

3b) The data processing module saves the part of the data sent by the first geomagnetic sensor A and the second geomagnetic sensor B where the vehicle passes, and adds a time stamp;

3) The data processing module aligns the saved data;

3a) First find the data when the car enters the two geomagnetic sensors A and B, and then find the data when the car leaves the two geomagnetic sensors A and B;

3b) Align the data of the initial moment of the geomagnetic sensor A and the geomagnetic sensor B, that is, the first data, and then sequentially align the second data and the third data collected by the two sensors during the driving process of the car... ...the nth data is aligned until the car leaves sensor A and sensor B, where n is the number of data collected by the sensor;

4) Calculate the time difference Δt that the car passes through the first sensor A and the second sensor B:

4a) Calculate the time difference between the first data after alignment, the time difference between the second data, ... the time difference between the nth data, until the time difference between the last data is calculated;

4b) Take the mean value of the time difference between all the data, which is the time difference Δt when the car passes through the two magnetic field data sensors;

5) Obtain the distance d between the geomagnetic sensor A and the geomagnetic sensor B in the system, and calculate the speed of the car according to the time difference Δt:

6) Test information reporting:

6a) The data processing module sends the vehicle speed data to the base station through the data reporting module;

8b) The base station will report the acquired vehicle speed data to the traffic data analysis platform at intervals.

Compared with the prior art, the present invention has the following advantages:

First, the system of the present invention can accurately and timely detect the speed of passing vehicles through the geomagnetic sensor deployed beside the road, and at the same time, according to the average vehicle speed of the detected road, it can provide the best driving path for the vehicle, thereby improving the level of road intelligence.

Second, the installation is convenient and the cost is low. The system of the invention adopts a geomagnetic sensor, which has a lower price compared with a common sensor required for Doppler radar speed measurement; the required data processing module can use a low-power microprocessor, which is cheap. The installation of the system does not require auxiliary equipment such as a gantry, so the system is easy to install, low in cost, and suitable for large-scale deployment.

Second, it has high reliability and is less affected by environmental factors. Compared with traditional video signals such as cameras, the geomagnetic sensor used in the system of the present invention is not affected by bad weather such as rain and snow, and environmental factors have little influence on the detection performance of traffic flow.

Third, the system of the present invention uses a geomagnetic sensor, so that pedestrians and non-motor vehicles will not cause fluctuations in the geomagnetic field or the system will not determine that there are vehicles passing by when the pedestrians and non-motor vehicles pass by, so the impact caused by pedestrians and other non-motor vehicles can be effectively avoided. .

Fourth, longer life. The system of the invention adopts a geomagnetic sensor with a volume of more than ten millimeters, and the volume is small. Compared with the geomagnetic coil, the sensor has a longer life and is less affected by ground vibration, and has better application prospects.

Fifth, the sensitivity is high. The geomagnetic sensor used in the present invention has high sensitivity to motor vehicles, and does not need to be installed in the middle of the road, but only needs to be installed in the road test to detect the motor vehicle, without large-scale damage to the road surface.

Description of drawings

In order to explain the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention, which are of great significance to the art For those of ordinary skill, other drawings can also be obtained from these drawings without any creative effort.

Fig. 1 is the overall structure block diagram of the system of the present invention;

Fig. 2 is the sensor deployment diagram in the system of the present invention;

Fig. 3 is the flow chart that the present invention utilizes dual geomagnetic velocity measuring system to measure velocity;

4 is a schematic diagram of the present invention performing data alignment in speed measurement;

FIG. 5 is a schematic diagram of geomagnetic waveforms provided by two geomagnetic sensors in the speed measurement of the present invention.

Detailed ways

The embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

1 , the vehicle speed detection system of the present invention includes a data processing module 1 , a data reporting module 2 , a base station module 3 , a dual geomagnetic sensor module 4 , and a power supply module 5 . The data processing module 1 is respectively connected with the data reporting module 2, the dual geomagnetic sensor module 4 and the power supply module 5; wherein, the data processing module 1 provides vehicle speed information to the data reporting module 2, and supplies power to the data reporting module 2; The two input terminals are respectively connected with the two geomagnetic sensors A and B of the dual geomagnetic sensor module 4, which are used to provide the data processing module 1 with geomagnetic data. The connection method can be connected either by wire or wirelessly. If Through wired connection, the data processing module 1 can also supply power to the dual geomagnetic sensor module 4; the power supply mode of the input end of the power supply module 5 can be all power supply modes such as solar energy, wind energy and commercial power. To ensure that the entire system works continuously 24 hours a day.

The data processing module 1 is mainly composed of a low power consumption processor and some peripheral circuits. The low-power processor in this example uses the M3 series processor based on the ARM system, but is not limited to other series processors authorized by ARM, including a series of processors based on X86 design and MSP430 series ultra-low power processors. power processor;

The data reporting module 2 is used for sending the obtained vehicle speed information to each base station module 3 . The technologies used in its transmission are mainly wireless technologies, such as a series of wireless technologies such as Bluetooth, Wi-Fi, and LoRa. Data reporting can also be performed in a wired manner without the use of a wireless transmitting device; in addition, a mobile data network can also be used to perform data reporting through the network by means of these communications. This example adopts but is not limited to data transmission through LoRa technology.

The base station module 3 is mainly responsible for the communication with each sensor, so as to obtain the vehicle speed sent by each sensor, and send the vehicle speed information to the traffic data analysis platform. The traffic data analysis platform conducts vehicle scheduling and accidents according to this data. If a speeding vehicle is found, the traffic data analysis platform can collect vehicle information based on nearby cameras.

The dual geomagnetic sensor module 4 is composed of two geomagnetic sensors A and B, and the connection between the two sensors and the data processing module 1 can be diversified, and can be wired or wireless. All wireless communication methods are included. The distance between the sensors is set according to the actual situation or the size of the sensor system. As long as the time difference between the two sensors passing by the car can be obtained through the difference between the positions of the dual geomagnetic sensors, and the speed of the car can be obtained. In the geomagnetic sensor module 4, the RM3100 digital three-axis geomagnetic sensor is used in this example, but it is not limited to other geomagnetic sensors and large dynamic range linear sensors on the market, which can reflect the change of the geomagnetic field. The geomagnetic sensor of the shaft is not limited to the geomagnetic sensor using digital signals and analog signals.

The power supply module 5 is mainly used to supply power to the entire system, and its output end can be connected in two ways: the first is to connect with the other input end of the data processing module 1 to provide the data processing module with the required power , and the data processing module supplies power to each module. The second is that the power supply module 5 is respectively connected to each module of the system and supplies power to each module respectively. This example adopts but is not limited to the first connection method.

Referring to Fig. 3, the present invention utilizes the dual geomagnetic speed measurement system to carry out the method for speed measurement, and the implementation steps are as follows:

Step 1: Deploy geomagnetic vehicle speed detection sensors according to actual needs.

The sensors are deployed on the buildings on the side of the road or underground according to the actual needs. The geomagnetic sensor can detect the speed of the vehicle whether it is on the side of the road or underground.

Referring to Figure 2, in this example, two geomagnetic sensors A and B are deployed on the side of the road to be detected, and the first sensor A is placed in front and the second sensor B is placed in the back, that is, the car passes through sensor A first and then passes through sensor B. Install the two sensors according to the set distance d=20. The distance d can be adjusted according to the actual needs and the technical requirements at the time. Set the communication mode between the sensors and the data processing module as wired communication or wireless communication according to the needs. This example adopts the way of wired communication.

Step 2, the geomagnetic sensor collects geomagnetic field data.

As shown in Figure 5, when a car passes by, the waveforms of sensor A and sensor B will change, that is, when a car passes by, the data of the geomagnetic field in sensor A will first fluctuate, and then the data in sensor B will fluctuate. These two geomagnetic sensors are real-time Collect the data of the local magnetic field, and transmit the obtained data to the data processing module through the communication method described in step 1.

Step 3. The data processing module analyzes the data transmitted by the two sensors to determine whether a vehicle passes by.

3.1) According to the fluctuation of the magnetic field data in the first geomagnetic sensor A, if the magnetic field data of sensor A fluctuates more than 60nT for 10 consecutive data, the data processing module judges that the car has passed, and if so, saves the geomagnetic data when the car passes, And execute step 3.2), otherwise, go back to step 2.

3.2) The data processing module further judges whether the data mark of the second geomagnetic sensor B is a car, and the judgment method is the same as that of step 3.1): if so, it is determined that there is a car passing by, and the geomagnetic data is saved, otherwise, return to step 2.

3.3) The data processing module stores the part of the data sent by the first geomagnetic sensor A and the second geomagnetic sensor B where the vehicle passes, and adds a time stamp.

Step 4. The data processing module adds a time stamp to the stored geomagnetic data.

4.1) When the car passes by, the data processing module finds the initial time t ₀ of the detection range of the car input sensor, and collects one piece of data each time to obtain time information. The method of obtaining the time can be obtained through the clock module of the processor, or according to the base station module. Obtain the time information in the issued command.

得到采样间隔，再由第N个地磁数据与第1个地磁数据的时间间隔NT，获取到每个数据的时间：t_n＝t₀+NT；In this example, the time information is obtained through the clock module in the processor, that is, through the time t ₀ of the first geomagnetic data, according to the sampling frequency f of the magnetic field, by the formula

Obtain the sampling interval, and then obtain the time of each data from the time interval NT of the Nth geomagnetic data and the first geomagnetic data: t _n =t ₀ +NT;

4.2) Add the time information obtained in 4.1) to the corresponding magnetic field data until the car leaves the geomagnetic sensor A and the geomagnetic sensor B respectively.

Step 5. Align sensor A with sensor B data.

5.1) The data processing module will find the data at the initial moment when the car enters sensor A and sensor B as the first data for alignment, and find the data at the moment when the car leaves sensor A and sensor B as the last data for alignment:

5.2) Align the first data, second data, third data of sensor A and sensor B in turn, until the last data alignment is completed, as shown in Figure 4.

Step 6. Calculate the time difference Δt for the car to pass the two sensors.

In step 5 to obtain the aligned data, compare the first data t _A1 , the second data t _A2 , the third data t _A3 . . . of sensor A with the first data t _B1 and the second data t of sensor B _B2 , the time information of the third data t _B3 ... is different, and the difference Δt _i between each data is obtained, then the time difference between the car passing through the sensor A and the sensor B is:

Step 7. Calculate the vehicle speed v.

According to step 2 to obtain the distance d between the two sensors and step 6 to obtain the time difference Δt between the two sensors, the speed of the car is calculated:

Step 8. Report the processed data.

The data processing module calculates the speed information and sends it to the base station module through the data transmission module. The base station can receive the data information reported by multiple speed measurement systems, and the base station module then reports the data information reported by each module to the traffic data analysis platform.

The invention achieves the overall goals of low power consumption, low cost, high reliability and strong applicability, realizes the intelligent and information-based construction of the deployment area, is suitable for the construction of smart highways, and plays a vital role in assisting the safety of unmanned driving. effect. The system of the present invention collects road speed information in real time and accurately by deploying geomagnetic sensors, and monitors in real time whether abnormal behaviors such as overspeed occur on the road surface. In addition, through large-scale and low-cost deployment, the range of speeding detection can be further improved, the incidence of traffic accidents can be reduced, and road safety can be ensured.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited to this. Any person skilled in the art can easily think of various equivalents within the technical scope disclosed by the present invention. Modifications or substitutions should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (8)

1. A speed measurement system based on dual geomagnetic sensors, comprising: a data processing module (1), a data reporting module (2), a base station module (3) and a power supply module (5); a data reporting module (2) and a data processing module (1) Wired connection, the data reporting module (2) is wirelessly connected with the base station module (3), and it is characterized in that: the input end of the data processing module (1) is connected with a dual geomagnetic sensor module (4), and the dual geomagnetic sensor module ( The two geomagnetic sensors A and B in 4) collect the magnetic field data around them respectively, transmit them to the data processing module (1) to save them, and judge whether there is a vehicle passing the detection range of the sensor according to the data, and calculate the speed of the vehicle output to the data reporting module (2); the data reporting module sends the vehicle speed information to the base station module (3), and the base station module reports the vehicle speed data received from each data reporting module to the traffic data analysis platform. 2. The system according to claim 1, characterized in that: the output end of the power supply module (5) is connected to the data processing module (1), and the power supply mode of the input end of the power supply module adopts all power supply modes of solar energy, wind energy or commercial power. 3. The system according to claim 1, wherein the geomagnetic sensor comprises: a digital geomagnetic sensor, an analog geomagnetic sensor, a single-axis geomagnetic sensor and a multi-axis sensor. 4 . The system according to claim 1 , wherein the magnetic field data refers to fluctuating magnetic field data detected by all geomagnetic sensors when there is a car passing by and relatively stable magnetic field data when no car passing by, wherein, there is a car passing by. The fluctuation range of the magnetic field when passing by exceeds 50nT, and the fluctuation range of the magnetic field when no vehicle passes by is not more than 20nT. 5 . The system according to claim 1 , wherein the two sensors A and B are placed in front and back, and the vehicle passes through the sensor A and the sensor B in sequence when driving. 6 . 6. a method utilizing the described system of claim 1 to test vehicle speed, is characterized in that, comprises as follows: 1) In the system, two geomagnetic sensors A and B respectively collect the magnetic field data of the location of the sensor in real time, and transmit them to the data processing module in turn; 2) The data processing module parses the data transmitted by the two sensors: 2a) The data processing module determines whether the data mark of the first geomagnetic sensor A is a car: if so, it is determined that there is a car passing by, and 3b) is executed, otherwise, 1) is returned; 2b) The data processing module judges whether the data flag of the second geomagnetic sensor B is a car: if so, it is judged that a car passes by, and executes 3b), otherwise, returns to 1); 3b) The data processing module saves the part of the data sent by the first geomagnetic sensor A and the second geomagnetic sensor B where the vehicle passes, and adds a time stamp; 3) The data processing module aligns the saved data; 3a) First find the data when the car enters the two geomagnetic sensors A and B, and then find the data when the car leaves the two geomagnetic sensors A and B; 3b) Align the data of the initial moment of the geomagnetic sensor A and the geomagnetic sensor B, that is, the first data, and then sequentially align the second data and the third data collected by the two sensors during the driving process of the car... ...the nth data is aligned until the moment when the car leaves sensor A and sensor B, where n is the number of data collected by the sensor; 4) Calculate the time difference Δt that the car passes through the first sensor A and the second sensor B: 4a) Calculate the time difference between the first data after alignment, the time difference between the second data, ... the time difference between the nth data, until the time difference between the last data is calculated; 4b) Take the mean value of the time difference between all the data, which is the time difference Δt when the car passes through the two magnetic field data sensors; 5) Obtain the distance d between the geomagnetic sensor A and the geomagnetic sensor B in the system, and calculate the speed of the car according to the time difference Δt:

6) Test information reporting: 6a) The data processing module sends the vehicle speed data to the base station through the data reporting module; 8b) The base station will report the acquired vehicle speed data to the traffic data analysis platform at intervals. 7. The method according to claim 6, wherein the time stamp in step 3b) refers to the instantaneous time when the sensor collects the geomagnetic data, and the time is obtained by the clock module in the central processing, or unified by the base station. The time data sent is obtained. 8. method according to claim 6 is characterized in that, the data alignment in 3b) is to align the initial moment when the car enters the monitoring range of two geomagnetic sensors, or the data alignment at the moment when the car leaves two geomagnetic sensors, Or align the moments with the most obvious geomagnetic characteristics of the two geomagnetic sensors, that is, the moments of the highest fluctuation point or the lowest point of data fluctuation.

Images