CN110672294A - System and method for researching following flow field in road environment - Google Patents

Abstract

The invention discloses a system for researching a vehicle following flow field in a road environment, comprising an anemometer, a GPS device, a laser radar and a computer; The anemometer, GPS equipment, and lidar are respectively connected to the computer, and the collected data information is fed back to the computer, and the computer processes and stores the data. The invention also discloses a method for studying the following flow field in the road environment. The present invention can be used in the actual road environment, the equipment is simple, and the required information can be separated through simple vector addition and subtraction calculation.

Description

A system and method for studying vehicle following flow field in road environment

technical field

The present invention specifically relates to a system and method for researching a vehicle following flow field in a road environment.

Background technique

The general technology for studying the flow field outside the vehicle is to use particle image velocimetry (PIV) to test in the experimental wind tunnel environment. This technology is widely used in flow field research and can obtain the flow field distribution on the plane. The basic principle of PIV technology is to shoot two similar particle images with a high-speed camera, and determine the relationship between particles in the two images through cross-correlation processing. In addition to PIV technology, body pressure measurement equipment is often used in wind tunnels to collect pressure data. By drilling holes on the car model and installing pressure sensors, the pressure of the vehicle and surface under different wind speeds is studied. Both PIV technology and body pressure measurement technology are technologies that can only be used for flow field research in the laboratory, and cannot be used in the actual road environment.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned problems, the present invention provides a system and method for studying the following flow field in a road environment.

In order to achieve the above object, the present invention adopts the following technical solutions:

A system for studying the vehicle following flow field in the road environment, including anemometer, GPS equipment, lidar and computer; In the car; the anemometer, GPS equipment, and lidar are respectively connected to the computer, and the collected data information is fed back to the computer, and the computer processes and stores the data;

The anemometer can collect wind speed information including vehicle motion, ambient wind and the influence of the vehicle ahead, and transmit it to the computer in real time;

The lidar collects the distance between the test vehicle and the vehicle in front, and the shape information of the rear of the vehicle in front and transmits it to the computer in real time;

GPS equipment collects vehicle speed and direction information and transmits it to the computer in real time.

Further, when the test vehicle is following other vehicles, the anemometer collects wind speed information including vehicle motion, ambient wind and the influence of the vehicle ahead, and transmits it to the computer in real time; In the road environment, the data collected by the anemometer only contains the wind speed information of vehicle motion and ambient wind.

Further, there may be one or more anemometers.

The present invention also provides a method for studying the vehicle following flow field in a road environment, the method adopts the system described above, and includes the following steps:

(1) Install the anemometer, GPS equipment, and lidar on the flat roof of a general small vehicle that does not hinder driving, record the positions of the installation position relative to the body, and install the computer in the vehicle; anemometer, GPS equipment, The lidar is connected to the computer in the car through a data cable;

(2) Anemometer, GPS equipment, and lidar collect data in real time, and transmit the data to the computer in real time;

(3) The computer processes and stores the received data, and finally obtains the vector of the influence of the vehicle ahead, which is used as an index to study the influence of the vehicle ahead on the flow field.

The beneficial effects of the present invention are:

(1) The present invention is used to study the flow field state in different surrounding vehicle environments by installing anemometer, GPS, and vehicle-mounted radar above the vehicle. The present invention can be used in the actual road environment, the equipment is simple, and the required information can be separated by simple vector addition and subtraction calculation.

(2) Compared with the method of collecting pressure data by using the body pressure measuring equipment in the wind tunnel test, the present invention studies the external flow field of the vehicle, and the measurement obtains the velocity vector. The more anemometers are used, the more the flow field information obtained is. many.

Description of drawings

FIG. 1 is a schematic structural diagram of each device in the system of the present invention installed on a test vehicle.

FIG. 2 is a schematic flowchart of the present invention to obtain the result of the influence of the vehicle ahead on the flow field.

Figure 3 is a schematic diagram of a computer processing and storing received data.

FIG. 4 is a schematic diagram of the separation process of ambient wind factors in a road environment with no vehicles ahead.

FIG. 5 is a schematic diagram of the separation process of ambient wind factors in a road environment with vehicles ahead.

FIG. 6 is a schematic diagram of the influence of different vehicle tail shapes on the flow field.

Detailed ways

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings. It should be noted that the specific embodiments are only detailed descriptions of the present invention and should not be regarded as limitations of the present invention.

A system of the present invention for studying the vehicle following flow field in a road environment includes an anemometer 2, a GPS device 4, a laser radar 3 and a computer 1; the computer 1 can be installed in the vehicle, and the anemometer 2, GPS equipment 4, The lidar 3 needs to be installed on the flat roof of the vehicle and does not hinder driving.

In some preferred manners, the computer 1 is installed in the vehicle, in order to avoid the damage of vibration reduction, it can be fixed, and at the same time, certain shock absorption measures can be taken.

In some preferred manners, there may be one or more anemometers 2 .

In some preferred manners, when installing an anemometer 2, the anemometer 2 needs to be installed in the flat area closest to the front end of the vehicle on the central axis of the vehicle;

The lidar 3 needs to be installed at the left or right rear more than 30cm away from the anemometer, so as to avoid affecting the anemometer, and the front of the lidar 3 should not be blocked by the anemometer 2;

The GPS device 4 needs to be installed behind the anemometer 2 and the lidar 3, in the middle of the roof.

In some preferred manners, when multiple anemometers 2 are to be installed, the anemometer 2 should be kept at a distance of more than 30 cm from other devices, and try to avoid blocking by other devices in front of the anemometer 2 .

In some preferred manners, the lines of the anemometer 2, the GPS device 4, and the lidar 3 can be connected to the computer 1 in the vehicle through the opened side window of the vehicle. As shown in FIG. 1 , the anemometer 2 , the GPS device 4 , and the lidar 3 are respectively connected to the computer 1 and feed back the collected data information to the computer 1 , and the computer 1 processes and stores the data.

In some preferred manners, the anemometer 2 can measure the magnitude and direction of the wind speed and transmit it to the computer 1 according to a certain data format.

In some preferred manners, as shown in FIG. 2 , when the test vehicle is following other vehicles, the anemometer 2 collects wind speed information including vehicle motion, ambient wind and the influence of the vehicle ahead, and transmits it in real time. Go to computer 1; when the test vehicle is in a road environment with no vehicles in front of it, there is no vehicle in the visible distance ahead or a distance of more than 100 meters from the vehicle in front can be regarded as a road environment without vehicles in front, and the data collected by anemometer 2 only includes vehicles. Wind speed information of motion and ambient wind; wind speed information includes wind speed magnitude and direction, namely wind speed vector;

In some preferred manners, the lidar 3 emits a laser beam to detect and collect the distance between the test vehicle and the vehicle in front, and the shape information of the rear of the vehicle in front, and transmit it to the computer 1 in real time.

In some preferred manners, the GPS device 4 collects the driving speed and direction information of the test vehicle through satellite positioning and transmits it to the computer 1 in real time; the driving speed and direction of the test vehicle are the vehicle speed vector.

In some preferred manners, the process of processing and storing the received data information by the computer 1 is shown in Figure 2-3, and the wind speed data collected by the anemometer 2 includes wind speed magnitude and direction information, that is, the wind speed vector.

Part of the GPS device 4 itself has the function of obtaining the wind speed vector by derivation of the time according to the position information of the two points. For the position data of two adjacent points, the computer 1 processes the position data, and the obtained speed vector has the same direction as the vehicle's traveling direction, that is, the vehicle speed vector. The vehicle speed vector includes the vehicle speed and direction information.

The data given by the lidar 3 is the point cloud data of the vehicle ahead, including the position and distance information of each point. The computer 1 extracts the distance data between the test vehicle and the vehicle ahead and the external dimension data of the rear of the front vehicle.

The wind speed vector, the vehicle speed vector and the distance data obtained above are stored in the computer 1 according to the corresponding time, and the external dimension data of the vehicle tail is stored in the computer 1 according to the front vehicle corresponding to the detection.

In some preferred ways, in an open road environment without a vehicle ahead, the separation process of environmental wind factors is shown in Figure 4, and states A and B respectively represent the coincidence and non-coincidence of the coordinate system of the anemometer 2 and the ground coordinate system. . The vehicle will be affected by environmental wind factors in the atmospheric environment. When the vehicle starts to drive, due to the movement of the vehicle relative to the atmospheric environment, the data collected by the anemometer 2 also includes the vehicle movement information, that is, the vehicle speed and direction information ( Expressed in the data is the vehicle speed vector), the vehicle speed vector can be obtained through the data collected by the GPS device. As shown in step ① in Figure 4, the wind speed vector and the vehicle speed vector are known information obtained; add the wind speed vector obtained in the driving state to the vehicle speed vector, or subtract the vector with the same magnitude and opposite direction as the vehicle speed vector, as shown in the figure As shown in step ② in 4, the external environmental wind factor (expressed as an environmental wind vector on the data) under the driving state of the test vehicle can be obtained. Due to the change of the direction of the road, the coordinate system of the anemometer 2 does not coincide with the ground coordinate system in most cases, which will cause the same ambient wind vector relative to the ground coordinate system to be different in the anemometer coordinate system. Since the anemometer coordinate system is based on the test vehicle, the angle between the vehicle speed vector and the ground coordinate system is the angle between the anemometer coordinate system and the ground coordinate system. The vector is restored to the ground coordinate system, as shown in B in step ③ in Figure 4. The computer 1 stores data at certain time intervals (every 1 second or shorter interval), by calculating the average value within 10-20 seconds as a reference value of the environmental wind factor, as a known condition, used in a road environment with vehicles ahead According to the length of the straight road and the speed of the vehicle, the time used to calculate the average value can be adjusted; the average value for a period of time is to reduce the influence of factors such as vehicle vibration and fine-tuning of the driving direction during the measurement process. error caused.

In a road environment with a vehicle ahead, the separation process of the three types of information data is shown in Figure 5; when the test vehicle follows other vehicles, the data collected by the anemometer 2 changes due to the influence of the vehicle in front. At this time, the anemometer 2 The data collected is wind speed information that includes vehicle motion and ambient wind and the influence of the vehicle ahead. As shown in step ① in Figure 5, the wind speed vector and the vehicle speed vector are known information obtained; add the wind speed vector obtained in the driving state to the vehicle speed vector (or subtract the vector with the same magnitude and opposite direction as the vehicle speed vector), such as As shown in step (2) in Fig. 5, the first result vector can be obtained. The vector includes the ambient wind information and the wind speed information influenced by the vehicle ahead. The ambient wind vector referenced above is used in the road environment with no vehicle ahead. value, subtract the ambient wind vector from the first result vector to obtain the second result vector, as shown in step ③ in Figure 5, the second result vector includes the vector that is influenced by the vehicle ahead, and is used to study the influence of the vehicle ahead on the flow field. index.

The present invention also provides a method for studying the vehicle following flow field in a road environment, the method adopts the system described above, and includes the following steps:

(1) Install the anemometer 2, the GPS device 4, and the lidar 3 on the roof of a general small vehicle or other flat parts that do not hinder driving, record the relative positions of the installation position relative to the vehicle body, and install the computer 1 in the vehicle; The anemometer 2, GPS device 4, and lidar 3 are connected to the computer 1 in the car through a data cable; multiple anemometers 2 can be installed; the more anemometers 2 are used, the more flow field information is obtained.

(2) Anemometer 2, GPS device 4, LiDAR 3 record data in real time, and transmit the data to computer 1 in real time;

(3) The computer 1 processes and stores the received data, and finally obtains the vector of the influence of the preceding vehicle, which is used as an index for studying the influence of the preceding vehicle on the flow field.

Claims (4)

1. A system for researching a traffic following flow field in a road environment is characterized by comprising an anemoscope, GPS equipment, a laser radar and a computer; the anemoscope, the GPS equipment and the laser radar can be arranged at a smooth part on the roof of the vehicle without interfering with driving, and the computer is arranged in the vehicle; the anemoscope, the GPS equipment and the laser radar are respectively connected with the computer and feed back the collected data information to the computer, and the computer processes and stores the data;

the anemoscope can acquire wind speed information including vehicle motion, environmental wind and influence brought by a front vehicle, and transmits the wind speed information to the computer in real time;

the laser radar collects the distance between the test vehicle and the front vehicle and the shape information of the tail part of the front vehicle and transmits the distance and the shape information to the computer in real time;

the GPS equipment collects the information of the running speed and the running direction of the vehicle and transmits the information to the computer in real time.

2. The system for researching the traffic following flow field in the road environment as claimed in claim 1, wherein when the test vehicle is running along with other vehicles, the anemoscope collects the wind speed information including vehicle motion, environmental wind and influence of vehicles ahead, and transmits the wind speed information to the computer in real time; when the test vehicle is in a road environment without vehicles in front, the data collected by the anemoscope only comprises the vehicle motion and the wind speed information of the environmental wind.

3. The system for researching the following flow field in the road environment as claimed in claim 1, wherein the anemometer can be one or more.

4. A method of studying a traffic following field in a road environment, the method using a system according to any one of claims 1-3, comprising the steps of:

(1) mounting an anemoscope, GPS equipment and a laser radar on a smooth part of the roof of a common small vehicle without interfering driving, recording each position of the mounting position relative to the vehicle body, and mounting a computer in the vehicle; the anemoscope, the GPS equipment and the laser radar are connected to a computer in the vehicle through data lines;

(2) the anemoscope, the GPS equipment and the laser radar acquire data in real time and transmit the data to the computer in real time;

(3) and the computer processes and stores the received data to finally obtain a vector influencing the front vehicle, and the vector is used as an index for researching the influence of the front vehicle on the flow field.

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