阅读说明：本技术 一种基于雷达的能见度感知的方法、系统及设备 (Visibility perception method, system and equipment based on radar ) 是由 郭晋鹏 张昌炎 曲博岩 于 2021-02-10 设计创作，主要内容包括：本发明实施例公开了一种基于雷达的能见度感知的方法、系统及设备,使用定标物回波衰减测量能见度,可以通过雷达使用较低发射功率进行能见度的测量。通过建立定标物回波衰减量与能见度之间的关系模型,可以获得道路能见度的大小,并且通过多个定标物的位置来确定整个路段各个区间的能见度大小。(The embodiment of the invention discloses a visibility sensing method, system and device based on radar. The method can obtain the road visibility by establishing a relation model between the echo attenuation of the calibration objects and the visibility, and determine the visibility of each section of the whole road section by the positions of a plurality of calibration objects.)

1. A radar-based visibility perception method, the method comprising:

in sunny weather, controlling a radar to transmit signals to a plurality of calibration objects arranged on a road and receive echo signals, and measuring echo power P of each calibration object_nAs a measure of the power P of the unattenuated echo_sn；

Under the current road environment, controlling the radar to transmit signals to the plurality of calibration objects and receive echo signals, and measuring the echo power P of each calibration object_nAs a current echo power measurement value P_tn；

According to the currentEcho power measurement P_tnAnd said unattenuated echo power measurement P_snCalculating the echo power attenuation A of each calibration object_rn(ii) a And

according to the attenuation quantity A of the echo power_rnReversing the first visibility between the targets

Wherein n is the reference number of the calibration object, n₁Is the reference number of the first subject matter, n₂Is the reference number of the second calibration object, n₁Greater than n₂。

2. The radar-based visibility perception method according to claim 1, wherein said first visibility isThe inversion formula of (a) is:

wherein, A (n)₁，n₂)＝A_rn1-A_rn2，n₁Is the reference number of the first subject matter, n₂Is the reference number of the second calibration object, n₁Greater than n₂C is a variable parameter, and a is a correction parameter.

3. The radar-based visibility perception method according to claim 1, wherein said method further comprises: according to the attenuation quantity A of the echo power_rnInverting a second visibility V between each target and the radar_nSaid second visibility V_nThe inversion formula of (a) is:

where c is a variable parameter and a is a correction parameter.

4. The radar-based visibility sensing method according to claim 1, wherein the echo power P of each scaling object is_nThe measuring method comprises the following steps:

acquiring echo signals in a radar detection range after the calibration objects are arranged;

dividing unit areas of all calibration objects according to the radial distance, azimuth angle and pitch angle relative to the radar to form radar echo signal point cloud data; and

extracting echo signal intensity A of each calibration object from the grid corresponding to the unit area_nDirectly with said echo signal intensity A_nAs said echo power P_nOr according to the echo signal intensity A_nDetermining the echo power P_n。

5. Method for radar-based visibility perception according to any of the claims 1 to 4, characterized in that said non-attenuated echo power measure P_snAnd said current echo power measurement P_tnAnd repeating the measurement for multiple times according to the preset interval time, and obtaining an average value after smooth filtering treatment.

6. The radar-based visibility perception method according to claim 5, wherein said echo signal strength A is based on_nDetermining the echo power P_nWhich comprises the following steps:

using said echo signal intensity A_nObtaining a frequency domain model of a target signal after fast Fourier transform, identifying a noise signal according to the range-Doppler characteristics of the target, and calculating to obtain the system noise signal level N of each calibration object_n；

Continuously measuring the noise signal for m times to obtain the signal-to-noise ratio R of the current target signal of each calibration object_nThe target signal-to-noise ratio calculation formula is as follows:

SNR_nj＝A_nj/N_nj

wherein A is_njEcho signal intensity of individual calibration objects for j-th measurement, N_njSystem noise signal level, SNR, for each target measured for the jth_njThe signal to noise ratio of each calibration object measured for the jth time;

estimating the current noise level H of the radar receiving system, wherein the estimation formula of the current noise level H is as follows:

H＝K·T·B·N_r·G/λ

wherein K is Boltzmann constant, T is the operating temperature of the radar receiver, B is the frequency of the signal received by the radar receiver, N_rThe system noise coefficient is G, the gain of the radar receiver is G, and the wavelength of a radar receiving signal is lambda;

calculating the signal-to-noise ratio R of the current target signal_nMultiplying the current noise level H to obtain a first measured echo power value P of each calibration object¹ _rn；

Inputting signals from a high-amplification input end of a receiver of the radar by using a radar signal comprehensive tester, and increasing the output power P of a signal source from the sensitivity of the radar receiver according to a preset interval_rFor each P_rRecording the corresponding sampled A/D value until the receiver is saturated, obtaining one of said output powers P_rA corresponding table of the sampling A/D value is used for obtaining a calibration curve of the A/D value and the power value by using a least square method for data in the corresponding table;

obtaining the expected power value of the echo signal according to the calibration curve and the sampling A/D value of the current radar to the target echo signalUsing the expected power value of the echo signalWith said first measured echo power value P¹ _rnAs the second measured echo power value P of the respective calibration object² _rn；

Simulating a radar target by using a target simulator, and measuring for i times by using the radar to obtain each third measured echo power value P³ _riAnd true echo power is Q_iThe correction coefficient C is obtained according to the following correction coefficient calculation formula:

the second measured echo power value P is corrected by a correction factor C² _rnThe echo power P of each calibration object is obtained by correction_n(ii) a The correction formula is as follows:

P_n＝P² _rn+C。

7. the radar-based visibility perception method according to claim 5, wherein the echo power P of each calibration object_nThe measurement method of (2), further comprising: and performing clutter filtering on the radar echo signal point cloud data, wherein the clutter filtering comprises the following steps:

before the calibration object is installed, dividing a space region into a plurality of three-dimensional networks with unit sizes in a detection range of a radar, and numbering the divided space regions;

acquiring echo signals in a radar detection range before arrangement of the calibration objects, and accumulating the number of clutter points in each space region; positioning a space region with the number of points accumulated in unit time exceeding a preset accumulation threshold as a static clutter region, and storing the number of the static clutter region to generate a static clutter table; performing clutter filtering on the radar echo signal point cloud data by using the static clutter table; and/or

Obtaining the radar detection range after the calibration object is arrangedAccumulating the number of clutter points on each space region of echo signals in the enclosure; calculating the current time t of each frame synchronous updating auxiliary clock_xThe starting time of the current accumulation period of the current space regionThe time difference between them; the time difference value is compared with the maximum preset accumulation time delta t_maxComparing, wherein x is the number of the current space area; if the time difference value is larger than the maximum preset accumulated time delta t_maxFor the historical accumulation value Num of the space region_xEmptying, accumulating again, and updating the start time of the current accumulation period in the current space regionIf the time difference is less than the maximum preset accumulation time At_maxThen the process loops to calculate the current time t of the synchronous updated auxiliary clock of each frame_xThe starting time of the current accumulation period of the current space regionThe time difference between them; if the time difference is equal to the maximum preset cumulative time delta t_maxEach frame traverses all spatial regions and updates the current cumulative value Num_xJudging the current accumulation value Num_xWhether the preset maximum accumulation threshold Num is reached_max(ii) a If the current accumulation value Num_xLess than a preset maximum cumulative threshold Num_maxPositioning the space region as a dynamic clutter region, and storing the serial number of the dynamic clutter region to generate a dynamic clutter table; and performing clutter filtering on the radar echo signal point cloud data by using the dynamic clutter table.

8. A radar-based visibility perception system, comprising:

the echo power measurement module of the calibration object is used for measuring the echo power of the calibration object in the clear weather/current road environmentControlling radar to transmit signals to and receive echo signals from a plurality of calibration objects arranged on a road, and measuring echo power P of each calibration object_n；

A module for obtaining echo power measurement value without attenuation, which is used for obtaining the echo power P of each calibration object measured in clear weather_nAs a measure of the power P of the unattenuated echo_sn；

A current echo power measurement value acquisition module for acquiring echo power P of each calibration object measured under the current road environment_nAs a current echo power measurement value P_tn；

An echo power attenuation calculation module for calculating the current echo power measurement value P_tnAnd said unattenuated echo power measurement P_snCalculating the echo power attenuation A of each calibration object_m(ii) a And

a first visibility inversion module for inverting the echo power attenuation A_rnReversing the first visibility between the targets

Wherein n is the reference number of the calibration object, n₁Is the reference number of the first subject matter, n₂Is the reference number of the second calibration object, n₁Greater than n₂。

9. The radar-based visibility perception system according to claim 8, wherein said system further comprises: a second visibility inversion module for inverting the echo power attenuation A_mInverting a second visibility V between each target and the radar_n。

10. A radar-based visibility-sensing apparatus, the apparatus comprising: a processor and a memory;

the memory is to store one or more program instructions;

the processor, configured to execute one or more program instructions to perform the steps of a radar-based visibility perception method according to any one of claims 1 to 7.

Technical Field

The embodiment of the invention relates to the technical field of visibility radar detection, in particular to a visibility sensing method, system and device based on radar.

Background

Measuring atmospheric visibility is generally measured using an atmospheric transmission instrument, a laser visibility automatic measuring instrument, a camera, and the like.

The atmospheric transmission instrument directly measures the transmissivity of an air column by a light beam penetrating through the air column between two fixed points so as to calculate the visibility value, the method requires that the light beam passes through the long enough air column, the measurement reliability is influenced by a light source and the working stability of other hardware systems, and the atmospheric transmission instrument is generally only suitable for observation of visibility below medium, and can cause larger errors due to complex conditions such as water vapor absorption and the like in weather with low visibility such as rain, fog and the like.

The automatic laser visibility measuring instrument calculates visibility by a method of measuring atmospheric extinction coefficient by laser, and is relatively objective and accurate. However, this instrument is expensive, expensive to maintain, complicated to operate, and difficult to observe normally even in rainy or foggy weather, and thus difficult to popularize.

The method of using a camera to capture images and then calculating visibility through a digital image processing technique has a fatal disadvantage that the visibility inversion measurement is greatly influenced by light at night and in poor-light weather.

The visibility measurement by using radar can solve the problem that the visibility detection performance is affected by weather. The existing method for measuring visibility by using radar deduces the visibility of fog according to the size of the echo of the fog. Due to the fact that fog has weak reflection capacity on radar signals, the method for inverting visibility by utilizing fog echo signals requires that the radar has large transmitting power and good receiver sensitivity. In addition, large transmission power means higher power consumption, and high heat generation of the device can reduce the service life of the device, which is more disadvantageous to miniaturization and reliability design. The method for determining the fog cluster by utilizing the signal to noise ratio can only determine whether the fog cluster exists, cannot judge the visibility of the fog and cannot give the specific position of the fog cluster.

The method can only obtain the visibility condition of a monitoring point, cannot detect the specific position of the foggy mass, and cannot measure the visibility condition of the whole road section.

Disclosure of Invention

Therefore, the embodiment of the invention provides a visibility sensing method, system and device based on radar, and aims to solve the technical problems that the visibility transmission power is high, the visibility condition of the whole road section cannot be measured and the like in the conventional radar detection method.

In order to achieve the above object, the embodiments of the present invention provide the following technical solutions:

according to a first aspect of embodiments of the present invention, there is provided a radar-based visibility perception method, including:

in sunny weather, controlling a radar to transmit signals to a plurality of calibration objects arranged on a road and receive echo signals, and measuring echo power P of each calibration object_nAs a measure of the power P of the unattenuated echo_sn；

Under the current road environment, controlling the radar to transmit signals to the plurality of calibration objects and receive echo signals, and measuring the echo power P of each calibration object_nAs a current echo power measurement value P_tn；

According to the current echo power measured value P_tnAnd said unattenuated echo power measurement P_snCalculating the echo power attenuation A of each calibration object_rn(ii) a And

according to the attenuation quantity A of the echo power_rnReversing the first visibility between the targets

Wherein n is the reference number of the calibration object, n₁Is the reference number of the first subject matter, n₂Is the reference number of the second calibration object, n₁Greater than n₂。

Further, the first visibilityThe inversion formula of (a) is:

wherein, A (n)₁,n₂)＝A_rn1-A_rn2，n₁Is the reference number of the first subject matter, n₂Is the reference number of the second calibration object, n₁Greater than n₂C is a variable parameter, and a is a correction parameter.

Preferably, the method further comprises: according to the attenuation quantity A of the echo power_rnInverting a second visibility V between each target and the radar_nSaid second visibility V_nThe inversion formula of (a) is:

where c is a variable parameter and a is a correction parameter.

Further, the echo power P of each calibration object_nThe measuring method comprises the following steps:

acquiring echo signals in a radar detection range after the calibration objects are arranged;

dividing unit areas of all calibration objects according to the radial distance, azimuth angle and pitch angle relative to the radar to form radar echo signal point cloud data; and

extracting echo signal intensity A of each calibration object from the grid corresponding to the unit area_nDirectly with said echo signal intensity A_nAs said echo power P_nOr according to the echo signal intensity A_nDetermining the echo power P_n。

Preferably, said unattenuated echo power measurement P_snAnd said current echo power measurement P_tnAnd repeating the measurement for multiple times according to the preset interval time, and obtaining an average value after smooth filtering treatment.

Further, according to the echo signal intensity A_nDetermining the echo power P_nWhich comprises the following steps:

using said echo signal intensity A_nObtaining a frequency domain model of a target signal after fast Fourier transform, identifying a noise signal according to the range-Doppler characteristics of the target, and calculating to obtain the system noise signal level N of each calibration object_n；

Continuously measuring the noise signal for m times to obtain the signal-to-noise ratio R of the current target signal of each calibration object_nThe target signal-to-noise ratio calculation formula is as follows:

SNR_nj＝A_nj/N_nj

wherein A is_njEcho signal intensity of individual calibration objects for j-th measurement, N_njSystem noise signal level, SNR, for each target measured for the jth_njThe signal to noise ratio of each calibration object measured for the jth time;

estimating the current noise level H of the radar receiving system, wherein the estimation formula of the current noise level H is as follows:

H＝K·T·B·N_r·G/λ

wherein K is Boltzmann constant, T is the operating temperature of the radar receiver, B is the frequency of the signal received by the radar receiver, N_rThe system noise coefficient is G, the gain of the radar receiver is G, and the wavelength of a radar receiving signal is lambda;

calculating the signal-to-noise ratio R of the current target signal_nMultiplying the current noise level H to obtain a first measured echo power value P of each calibration object¹ _rn；

Inputting signals from a high-amplification input end of a receiver of the radar by using a radar signal comprehensive tester, and increasing the output power P of a signal source from the sensitivity of the radar receiver according to a preset interval_rFor each P_rRecording the corresponding sampled A/D value until the receiver is saturated, obtaining one of said output powers P_rA corresponding table of the sampling A/D value is used for obtaining a calibration curve of the A/D value and the power value by using a least square method for data in the corresponding table;

obtaining the expected power value of the echo signal according to the calibration curve and the sampling A/D value of the current radar to the target echo signalUsing the expected power value of the echo signalWith said first measured echo power value P¹ _rnAll areThe value of the second measured echo power value P is used as the value of the respective calibration object² _rn；

Simulating a radar target by using a target simulator, and measuring for i times by using the radar to obtain each third measured echo power value P³ _riAnd true echo power is Q_iThe correction coefficient C is obtained according to the following correction coefficient calculation formula:

the second measured echo power value P is corrected by a correction factor C² _rnThe echo power P of each calibration object is obtained by correction_n(ii) a The correction formula is as follows:

P_n＝P² _rn+C。

preferably, the echo power P of each of the calibrators_nThe measurement method of (2), further comprising: and performing clutter filtering on the radar echo signal point cloud data, wherein the clutter filtering comprises the following steps:

before the calibration object is installed, dividing a space region into a plurality of three-dimensional networks with unit sizes in a detection range of a radar, and numbering the divided space regions;

acquiring echo signals in a radar detection range before arrangement of the calibration objects, and accumulating the number of clutter points in each space region; positioning a space region with the number of points accumulated in unit time exceeding a preset accumulation threshold as a static clutter region, and storing the number of the static clutter region to generate a static clutter table; performing clutter filtering on the radar echo signal point cloud data by using the static clutter table; and/or

Acquiring echo signals in a radar detection range after the calibration objects are arranged, and accumulating the number of clutter points in each space region; calculating the current time t of each frame synchronous updating auxiliary clock_xThe starting time of the current accumulation period of the current space regionThe time difference between them; the time difference value is compared with the maximum preset accumulation time delta t_maxComparing, wherein x is the number of the current space area; if the time difference value is larger than the maximum preset accumulated time delta t_maxFor the historical accumulation value Num of the space region_xEmptying, accumulating again, and updating the start time of the current accumulation period in the current space regionIf the time difference value is less than the maximum preset accumulated time delta t_maxThen the process loops to calculate the current time t of the synchronous updated auxiliary clock of each frame_xThe starting time of the current accumulation period of the current space regionThe time difference between them; if the time difference is equal to the maximum preset cumulative time delta t_maxEach frame traverses all spatial regions and updates the current cumulative value Num_xJudging the current accumulation value Num_xWhether the preset maximum accumulation threshold Num is reached_max(ii) a If the current accumulation value Num_xLess than a preset maximum cumulative threshold Num_maxPositioning the space region as a dynamic clutter region, and storing the serial number of the dynamic clutter region to generate a dynamic clutter table; and performing clutter filtering on the radar echo signal point cloud data by using the dynamic clutter table.

Preferably, the plurality of scales are arranged at equal intervals.

According to a second aspect of embodiments of the present invention, there is provided a radar-based visibility perception system, the system comprising:

the echo power measurement module of the calibration object is used for controlling the radar to transmit signals to a plurality of calibration objects arranged on the road and receive echo signals under the environment of sunny weather/current road, and measuring the echo power P of each calibration object_n；

A module for obtaining the measured value of the power of the unattenuated echo, which is used for obtaining the measured value in the clear weatherEcho power P of each calibration object_nAs a measure of the power P of the unattenuated echo_sn；

A current echo power measurement value acquisition module for acquiring echo power P of each calibration object measured under the current road environment_nAs a current echo power measurement value P_tn；

An echo power attenuation calculation module for calculating the current echo power measurement value P_tnAnd said unattenuated echo power measurement P_snCalculating the echo power attenuation A of each calibration object_rn(ii) a And

a first visibility inversion module for inverting the echo power attenuation A_rnReversing the first visibility between the targets

Wherein n is the reference number of the calibration object, n₁Is the reference number of the first subject matter, n₂Is the reference number of the second calibration object, n₁Greater than n₂。

Preferably, the system further comprises: a second visibility inversion module for inverting the echo power attenuation A_rnInverting a second visibility V between each target and the radar_n。

Preferably, the plurality of scales are arranged at equal intervals.

According to a third aspect of embodiments of the present invention, there is provided a radar-based visibility sensing apparatus, the apparatus including: a processor and a memory;

the memory is to store one or more program instructions;

the processor is configured to execute one or more program instructions to perform the steps of a radar-based visibility perception method as described in any one of the above.

According to a fourth aspect of embodiments of the present invention, there is provided a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of a radar-based visibility perception method as described in any one of the above.

The embodiment of the invention has the following advantages:

the embodiment of the invention measures the visibility by using the echo attenuation of the calibration object, and can measure the visibility by using lower transmitting power through a radar. The method can obtain the road visibility by establishing a relation model between the echo attenuation of the calibration objects and the visibility, and determine the visibility of each section of the whole road section by the positions of a plurality of calibration objects.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.

The structures, ratios, sizes, and the like shown in the present specification are only used for matching with the contents disclosed in the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions that the present invention can be implemented, so that the present invention has no technical significance, and any structural modifications, changes in the ratio relationship, or adjustments of the sizes, without affecting the effects and the achievable by the present invention, should still fall within the range that the technical contents disclosed in the present invention can cover.

Fig. 1 is a schematic logical structure diagram of a radar-based visibility sensing system according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a road arrangement of a radar and a plurality of calibration objects according to an embodiment of the present invention;

FIG. 3 is a schematic flowchart of a method for radar-based visibility sensing according to an embodiment of the present invention;

FIG. 4 shows the echo power P of each calibration object according to an embodiment of the present invention_nFlow of the measuring methodA schematic diagram;

FIG. 5 shows the echo power P of each calibration object according to another embodiment of the present invention_nA schematic flow diagram of the measurement method of (1);

FIG. 6 shows an example of the echo signal strength A_nDetermining the echo power P_nA schematic flow diagram of (a);

fig. 7 is a schematic flowchart of a process of performing static clutter filtering on radar echo signal point cloud data according to an embodiment of the present invention;

fig. 8 is a schematic flowchart of a process of performing dynamic clutter filtering on radar echo signal point cloud data according to another embodiment of the present invention.

Detailed Description

The present invention is described in terms of particular embodiments, other advantages and features of the invention will become apparent to those skilled in the art from the following disclosure, and it is to be understood that the described embodiments are merely exemplary of the invention and that it is not intended to limit the invention to the particular embodiments disclosed. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

At present, the performance of a non-radar atmospheric visibility detection means is greatly influenced by weather, and the visibility is difficult to accurately measure in severe weather. At present, visibility measurement of fog by using radar is mainly applied to meteorological radar, and the visibility is inverted according to echo energy of the fog. This method requires a radar having a large transmission power because the echo energy of the mist is weak. For the measurement of the fog of road dough, whether the fog of the road dough appears or not is judged according to the signal-to-noise ratio, and the method is mainly used for judging whether the fog exists or not and cannot give the visibility. In addition, at present, the position of the fog cannot be given, only the visibility of a monitoring point can be obtained, and the visibility condition of the whole road section cannot be measured.

In order to solve the problems, the embodiment of the invention uses radar echo attenuation of the calibration object to measure the visibility, can use lower transmitting power to measure the visibility, and simultaneously avoids the influence of weather conditions. By establishing a relation model between attenuation and visibility, the road visibility can be obtained, and the visibility of each section of the road section can be determined through a plurality of calibration objects.

First, functional entities related to the embodiments of the present invention are described as follows, where the functional entities may be physical functional entities or logical functional entities, a single functional entity may serve as an independent device, or multiple functional entities may serve as an unified device. The technical solution is not limited thereto.

Referring to fig. 1, an embodiment of the present invention discloses a radar-based visibility sensing system, which includes: the system comprises: the device comprises an echo power measuring module 1 of a calibration object, an attenuation-free echo power measured value acquiring module 2, a current echo power measured value acquiring module 3, an echo power attenuation calculating module 4 and a first visibility inverting module 5.

The echo power measuring module 1 of the calibration object is used for controlling the radar to transmit signals to a plurality of calibration objects arranged on a road and receive echo signals under the environment of clear weather/current road, and measuring the echo power P of each calibration object_n(ii) a The non-attenuation echo power measured value acquisition module 2 is used for acquiring the echo power P of each calibration object measured in clear weather_nAs a measure of the power P of the unattenuated echo_sn(ii) a The current echo power measured value acquisition module 3 is used for acquiring the echo power P of each calibration object measured under the current road environment_nAs a current echo power measurement value P_tn(ii) a The echo power attenuation calculation module 4 is used for calculating the current echo power measured value P_tnAnd said unattenuated echo power measurement P_snCalculating the echo power attenuation A of each calibration object_rn(ii) a And the first visibility inversion module 5 is used for inverting the echo power attenuation A according to the echo power attenuation A_rnReversing the first visibility between the targetsWherein n is the reference number of the calibration object, n₁Is as followsA reference number of a calibration object, n₂Is the reference number of the second calibration object, n₁Greater than n₂。

In the embodiment of the invention, the echo power P of each calibration object is respectively measured and obtained under the environment of sunny weather/current road_n. Taking the measurement result in clear weather as the non-attenuation echo power measurement value, and comparing the measurement result in the current road environment with the non-attenuation echo power measurement value to obtain the echo power attenuation A of each calibration object_rThen, the first visibility between the respective targets is inverted. The method for measuring visibility by using radar echo attenuation of the calibration object is realized, and the problem that the visibility is easily influenced by weather conditions in non-radar detection is avoided. In addition, the visibility measurement using lower radar transmission power is realized. The visibility between the calibration objects can be obtained, namely, the visibility of each section of the whole road section is determined through the positions of a plurality of calibration objects.

Preferably, referring to fig. 1, the system for visibility sensing based on radar disclosed in the embodiment of the present invention further includes: a second visibility inversion module 6 for inverting the echo power attenuation A according to the echo power attenuation_rnInverting a second visibility V between each target and the radar_n。

Therefore, the embodiment of the invention not only can realize the detection of the visibility between the intervals of the various calibration objects, but also can detect the visibility between the intervals of the various calibration objects and the radar.

The calibration object related in the embodiment of the invention refers to: a device for reflecting radar signals is installed at a fixed position, and in a visibility measuring system, the visibility is inverted according to the attenuation of the energy of the echo signals of the device. Compared with other targets observed by the radar, the target has larger reflection sectional area, so that the target has stronger reflection capability and is easier to detect in clutter.

Further, the radar and the plurality of calibration objects in the embodiment of the invention are arranged on the road to be detected, and one radar simultaneously transmits signals to the plurality of calibration objects and receives echo signals of the calibration objects. Preferably, the plurality of scales are equally spaced. One possible mounting of the radar and the scale is shown in fig. 2, the radar 7 is mounted on an overhead beam of a road, a plurality of scales 8 are arranged on the road side, and the scales 8 are spaced apart by a certain distance, for example, a first scale 8 is spaced apart from the radar by 100m, a second scale 8 is spaced apart from the radar by 200m, a third scale 8 is spaced apart from the radar by 300m, a fourth scale 8 is spaced apart from the radar by 400m, and a fifth scale 8 is spaced apart from the radar by 500 m. The visibility perception system based on the radar disclosed in the embodiment of the invention realizes the functions of the modules through wireless communication or wired interaction with the radar.

Corresponding to the system for visibility perception based on the radar, the embodiment of the invention also discloses a method for visibility perception based on the radar. The visibility sensing method based on radar disclosed in the embodiments of the present invention is described in detail below with reference to the above-described visibility sensing system based on radar.

Referring to fig. 1 to 3, a method for visibility sensing based on radar disclosed in an embodiment of the present invention includes: under sunny weather, the echo power measuring module 1 of the calibration object controls the radar 7 to transmit signals to a plurality of calibration objects 8 arranged on a road and receive echo signals, and the echo power P of each calibration object 8 is measured_nThe echo power P measured at the moment is obtained by the non-attenuation echo power measured value obtaining module 2_nAs a measure of the power P of the unattenuated echo_snAnd sending the echo power attenuation quantity to an echo power attenuation quantity calculation module 4; under the current road environment, the echo power measuring module 1 of the calibration object controls the radar 7 to transmit signals to a plurality of calibration objects 8 and receive echo signals, and the echo power P of each calibration object 8 is measured_nThe current echo power measurement value acquisition module 3 acquires the echo power P measured at the moment_nAs a current echo power measurement value P_tnAnd sending the echo power attenuation quantity to an echo power attenuation quantity calculation module 4; the echo power attenuation quantity calculation module 4 calculates the current echo power measured value P_tnAnd a non-attenuated echo power measurement P_snDetermining the echo power attenuation A of each calibration object 8_rn(ii) a And is composed ofVisibility inversion module 5 according to echo power attenuation A_rnReversing the first visibility between the targetsWherein n is the reference number of the calibration object, n₁Is the reference number of the first subject matter, n₂Is the reference number of the second calibration object, n₁Greater than n₂。

In the embodiment of the invention, the echo power P of each calibration object is respectively measured and obtained under the environment of sunny weather/current road_n. Taking the measurement result in clear weather as the non-attenuation echo power measurement value, and comparing the measurement result in the current road environment with the non-attenuation echo power measurement value to obtain the echo power attenuation A of each calibration object_rThen, the first visibility between the respective targets is inverted. The method for measuring visibility by using radar echo attenuation of the calibration object is realized, and the problem that the visibility is easily influenced by weather conditions in non-radar detection is avoided. In addition, the visibility measurement using lower radar transmission power is realized. The visibility between the calibration objects can be obtained, namely, the visibility of each section of the whole road section is determined through the positions of a plurality of calibration objects.

Preferably, the method for visibility sensing based on radar disclosed in the embodiment of the present invention further includes: the second visibility inversion module 6 performs the inversion according to the echo power attenuation A_rnReversing the second visibility V between the respective target 8 and the radar 7_n. Therefore, the embodiment of the invention not only can realize the detection of the visibility between the intervals of the various calibration objects, but also can detect the visibility between the intervals of the various calibration objects and the radar.

Further, the first visibilityThe inversion formula of (a) is:

wherein, A (n)₁,n₂)＝A_rn1-A_rn2，n₁Is the reference number of the first subject matter, n₂Is the reference number of the second calibration object, n₁Greater than n₂C is a variable parameter, and a is a correction parameter.

Second visibility V_nThe inversion formula of (a) is:

where c is a variable parameter and a is a correction parameter.

The first visibilityAnd a second visibility V_nThe variable parameter c in the inverse equation of (a) depends on the mist particle size and the water content. In the embodiment of the invention, the variable parameter c is obtained through data fitting, specifically, enough corresponding data of the visibility V and the attenuation A of fog are obtained through laboratory simulation, and the value of the parameter c in the empirical formula model is obtained according to the fact that the visibility V and the attenuation A meet the inverse proportional relation fitting theoretical relational expression.

The first visibilityAnd a second visibility V_nThe correction parameter a in the inversion formula of (a) is calculated as follows: obtaining enough real visibility V through actual measurement_riData of corresponding attenuation A, byObtaining visibility inversion value V_iAccording to the formulaDetermining the actual visibility V_riInverse value V of visibility_iAverage value of deviation of (1), orderWherein f (A, c) is conventional in the art and will not be described herein.

Preferably, in this embodiment of the present invention, the measured value P of the echo power without attenuation is_snAnd the current echo power measurement value P_tnThe measurement is repeated for a plurality of times at preset intervals (for example, 5s), and the average value is obtained after the smoothing filtering processing.

Referring to FIG. 4, in one embodiment of the present disclosure, the echo power P of each calibration object_nThe measuring method comprises the following steps: obtaining an echo signal in a radar detection range after the calibration object 8 is arranged from the radar 7 by an echo power measuring module 1 of the calibration object; dividing unit areas of the calibration objects by an echo power measuring module 1 of the calibration objects according to the radial distance, azimuth angle and pitch angle of an echo signal source relative to a radar 7 to form radar echo signal point cloud data; and extracting the echo signal intensity A of each calibration object 8 from the grid of the corresponding unit area by the echo power measuring module 1 of the calibration object_n(ii) a The echo power measuring module 1 of the calibration object directly uses the echo signal intensity A_nAs echo power P_nOr according to the echo signal intensity A_nDetermining the echo power P_n。

In the embodiment of the invention, the echo signal strength A is used as the basis_nObtaining the echo power P of each calibration object_nThere are two methods of (1). One method is as follows: because the A/D quantized value of the radar receiver system has a better linear relation with the echo power, the change of the echo signal can be reflected in the change of the A/D quantized value, and therefore, the received echo signal strength A of each calibration object is directly used_nEcho power P as a corresponding target_n。

Referring to fig. 6, another method is preferably: according to the echo signal intensity A_nDetermining the echo power P_nThe method comprises the following specific steps:

using said echo signal intensity A_nObtaining a frequency domain model of the target signal after fast Fourier transform, according to the targetThe noise signal is identified by the distance-Doppler characteristic, and the system noise signal level N of each calibration object is calculated_n；

Continuously measuring the noise signal for m times to obtain the signal-to-noise ratio R of the current target signal of each calibration object_nThe target signal-to-noise ratio calculation formula is as follows:

SNR_nj＝A_nj/N_nj

wherein A is_njEcho signal intensity of individual calibration objects for j-th measurement, N_njSystem noise signal level, SNR, for each target measured for the jth_njThe signal to noise ratio of each calibration object measured for the jth time;

estimating the current noise level H of the radar receiving system, wherein the estimation formula of the current noise level H is as follows:

H＝K·T·B·N_r·G/λ

wherein K is Boltzmann constant, T is the operating temperature of the radar receiver, B is the frequency of the signal received by the radar receiver, N_rThe system noise coefficient is G, the gain of the radar receiver is G, and the wavelength of a radar receiving signal is lambda; wherein the system noise coefficient N_rObtained by the following method: connecting a frequency spectrograph and a signal comprehensive tester with a radar radio frequency output port, simulating an echo signal by using the signal comprehensive tester, and removing a target signal by using the frequency domain signal measurement capability of the frequency spectrograph, thereby measuring and obtaining a system noise coefficient Nr of the radar system at the moment;

calculating the signal-to-noise ratio R of the current target signal_nMultiplying the current noise level H to obtain a first measured echo power value P of each calibration object¹ _rn(ii) a I.e. P¹ _rn＝R_n·H；

Inputting signals from the high-amplification input end of the receiver of the radar by using the radar signal comprehensive tester, and sensitively sensing from the radar receiver according to a preset intervalThe output power P of the signal source starts to increase_rFor example, the predetermined interval may be 0.5dB for each P_rRecording the corresponding sampled A/D value until the receiver is saturated, obtaining one of said output powers P_rA corresponding table of the sampling A/D value is used for obtaining a calibration curve of the A/D value and the power value by using a least square method for data in the corresponding table;

obtaining the expected power value of the echo signal according to the calibration curve and the sampling A/D value of the current radar to the target echo signalUsing the expected power value of the echo signalWith said first measured echo power value P¹ _rnAs the second measured echo power value P of the respective calibration object² _rn；

Simulating a radar target by using a target simulator, and measuring for i times by using the radar to obtain each third measured echo power value P³ _riAnd true echo power is Q_iThe correction coefficient C is obtained according to the following correction coefficient calculation formula:

the second measured echo power value P is corrected by a correction factor C² _rnThe echo power P of each calibration object is obtained by correction_n(ii) a The correction formula is as follows:

P_n＝P² _rn+C。

because the measurement of the signal-to-noise ratio has a certain error, and the current noise power value is influenced by the environmental measurement clutter, the first measurement echo power value has a certain error. In the embodiment of the invention, the echo power P is obtained_nIn the method of (3), the echo signal is calibrated so as to be corrected according to a calibration curve. Measured in factThe average value of the difference value between the echo power and the true value obtained by the method is found to be within 0.1dB, and the measurement precision of the echo power is greatly improved.

Referring to FIG. 5, in another embodiment of the present disclosure, the echo power P of each calibration object_nThe measuring method comprises the following steps: obtaining an echo signal in a radar detection range after the calibration object 8 is arranged from the radar 7 by an echo power measuring module 1 of the calibration object; dividing unit areas of the calibration objects by an echo power measuring module 1 of the calibration objects according to the radial distance, azimuth angle and pitch angle of an echo signal source relative to a radar 7 to form radar echo signal point cloud data; the echo power measuring module 1 of the calibration object filters clutter from the radar echo signal point cloud data; and extracting the echo signal intensity A of each calibration object 8 from the grid of the corresponding unit area by the echo power measuring module 1 of the calibration object_n(ii) a The echo power measuring module 1 of the calibration object directly uses the echo signal intensity A_nAs echo power P_nOr according to the echo signal intensity A_nDetermining the echo power P_n。

That is, the present embodiment is different from the previous embodiment in that the echo power P of each calibration object_nThe measurement method of (2) further comprises: and performing clutter filtering on the radar echo signal point cloud data. In the present embodiment, the echo signal intensity A is determined according to_nObtaining the echo power P of each calibration object_nThere are two methods, which are not described herein.

Further, the clutter filtering of the radar echo signal point cloud data includes: static clutter filtering is carried out on the radar echo signal point cloud data, and referring to fig. 7, the method specifically comprises the following steps: before the calibration object 8 is installed, a space area is divided into a plurality of three-dimensional networks with unit sizes in the detection range of the radar 7, and the divided space areas are numbered; acquiring an echo signal in a radar detection range before arrangement of a calibration object 8 by an echo power measurement module 1 of the calibration object, and accumulating the number of clutter points in each space region; judging whether the number of points accumulated in unit time exceeds a preset accumulated threshold value or not by an echo power measuring module 1 of the calibration object, positioning a space area in which the number of points accumulated in unit time exceeds the preset accumulated threshold value as a static clutter area, and storing the number of the static clutter area to generate a static clutter table; the echo power measuring module 1 of the calibration object utilizes the static clutter table to filter clutter from the radar echo signal point cloud data; and when the number of the points accumulated in the unit time does not exceed the preset accumulation threshold, the static clutter identifier is abandoned.

Further, the clutter filtering of the radar echo signal point cloud data includes: the method comprises the following steps of carrying out dynamic clutter filtering on the point cloud data of the radar echo signals, and referring to fig. 8, wherein the method specifically comprises the following steps: before the calibration object 8 is installed, a space area is divided into a plurality of three-dimensional networks with unit sizes in the detection range of the radar 7, and the divided space areas are numbered; the echo power measuring module 1 of the calibration object obtains echo signals in a radar detection range after the calibration object 8 is arranged, and the number of clutter points is accumulated in each space region; calculating the current time t of each frame of synchronous updating auxiliary clock by the echo power measuring module 1 of the calibration object_xThe starting time of the current accumulation period of the current space regionThe time difference between them; the time difference value is compared with the maximum preset accumulated time delta t_maxComparing, wherein x is the number of the current space area; if the time difference value is larger than the maximum preset accumulated time delta t_maxFor the historical accumulation value Num of the space region_xEmptying, accumulating again, and updating the start time of the current accumulation period in the current space regionIf the time difference value is less than the maximum preset accumulated time delta t_maxCirculating to the above calculation to synchronously update the current time t of the auxiliary clock for each frame_xThe starting time of the current accumulation period of the current space regionThe time difference between them; if the time difference value is equal to the maximum preset accumulated time delta t_maxEach frame traverses all spatial regions and updates the current cumulative value Num_xJudging the current accumulation value Num_xWhether the preset maximum accumulation threshold Num is reached_max(ii) a If the current accumulated value Num_xLess than a preset maximum cumulative threshold Num_maxPositioning the space region as a dynamic clutter region, and storing the serial number of the dynamic clutter region to generate a dynamic clutter table; performing clutter filtering on the radar echo signal point cloud data by using the dynamic clutter table; if the current accumulated value Num_xReaches the preset maximum accumulation threshold value Num_maxContinuously accumulating on the previous basis, and not updating the starting time of the accumulation period of the current space area

In the embodiment of the invention, clutter filtering is carried out on the radar echo signal point cloud data, and static clutter filtering and dynamic clutter filtering can be simultaneously carried out on the radar echo signal point cloud data by utilizing the method. By clutter filtering, the echo power P of the environmental clutter on each calibration object is reduced_nThe measurement result is more accurate.

In addition, an embodiment of the present invention further provides a device for visibility perception based on radar, where the device includes: a processor and a memory; the memory is to store one or more program instructions; the processor is configured to execute one or more program instructions to perform the steps of a radar-based visibility perception method as described in any one of the above.

In addition, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the radar-based visibility sensing method as described in any one of the above.

In an embodiment of the invention, the processor may be an integrated circuit chip having signal processing capability. The Processor may be a general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete Gate or transistor logic device, discrete hardware component.

The various methods, steps and logic blocks disclosed in the embodiments of the present invention may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present invention may be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The processor reads the information in the storage medium and completes the steps of the method in combination with the hardware.

The storage medium may be a memory, for example, which may be volatile memory or nonvolatile memory, or which may include both volatile and nonvolatile memory.

The nonvolatile Memory may be a Read-Only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically Erasable PROM (EEPROM), or a flash Memory.

The volatile Memory may be a Random Access Memory (RAM) which serves as an external cache. By way of example and not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), SLDRAM (SLDRAM), and Direct Rambus RAM (DRRAM).

The storage media described in connection with the embodiments of the invention are intended to comprise, without being limited to, these and any other suitable types of memory.

Those skilled in the art will appreciate that the functionality described in the present invention may be implemented in a combination of hardware and software in one or more of the examples described above. When software is applied, the corresponding functionality may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer.

Although the invention has been described in detail above with reference to a general description and specific examples, it will be apparent to one skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.