Radar pitch angle calibration method and device, electronic equipment and storage medium

Abstract

The embodiment of the invention provides a radar pitch angle calibration method and device, electronic equipment and a storage medium, and the electronic equipment can determine a distance dimension range and a speed dimension range in a distance Doppler map, obtains a ground clutter region, selects a plurality of candidate ground clutter points from the ground clutter region, and carries out the calibration of the pitch angle of a radar according to the distance values of the candidate ground clutter points and the radar installation height. Calculating a standard pitch angle of the radar; calculating pitch angle deviation based on the standard pitch angle and the pitch angle detected by the radar; and calibrating the pitch angle of the radar according to the relationship between the pitch angle deviation and a preset deviation range. The distance between the ground point and the radar can be calculated through the distance value of the ground clutter point and the distance resolution of the radar, the standard pitch angle can be calculated by combining the installation height of the radar, the standard pitch angle is the pitch angle without installation errors, the pitch angle detected by the radar is the pitch angle with the installation errors, and through the difference between the standard pitch angle and the pitch angle detected by the radar, the distance between the ground clutter point and the radar can be calculated. The pitch angle deviation of the radar can be determined, and the pitch angle of the radar can be calibrated.

Description

Technical Field

[0001] The present application relates to the technical field of radar calibration, and in particular to a calibration method, device, electronic equipment and storage medium for radar elevation angle. Background Art

[0002] Vehicle-mounted radar is a sensor installed on a vehicle that can determine the information of environmental objects through the characteristics of the reflected echo signal, such as the distance, azimuth, pitch angle, and Doppler of the environmental objects. In the field of autonomous driving, the role of vehicle-mounted radar is particularly important and can be used for cruise control, emergency braking, blind spot monitoring, etc.

[0003] As the vehicle moves, the vehicle-mounted radar may have installation errors in the pitch direction. Once such errors occur, the vehicle-mounted radar will seriously affect the accuracy of target height detection, and then affect the detection of ground obstacles, bringing greater safety hazards. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a radar pitch angle calibration method, device, electronic device and storage medium to achieve pitch angle calibration of vehicle-mounted radar and avoid safety hazards caused by installation errors in the pitch direction of the vehicle-mounted radar. The specific technical solution is as follows:

[0005] In a first aspect, an embodiment of the present application provides a method for calibrating a radar pitch angle, wherein the radar is installed on a vehicle, and the radar is used to transmit a radar signal to the outside world and receive an echo signal reflected by the outside world, and the method includes:

[0006] Acquire a range Doppler map obtained by processing the echo signal collected by the radar, wherein the echo signal is collected by the radar when the driving state of the vehicle meets a preset calibration condition, the preset calibration condition includes a preset uniform straight-line driving condition and a preset flat road surface condition, and the range Doppler map is a two-dimensional relationship diagram between distance and speed;

[0007] Determining a range dimension range and a speed dimension range in the range Doppler map to obtain a ground clutter region, wherein the ground clutter region is a region corresponding to an echo signal reflected from the ground collected by the radar when the driving state of the vehicle meets the preset calibration condition;

[0008] Selecting a plurality of candidate ground clutter points from the ground clutter area, and calculating a standard pitch angle of the radar corresponding to each candidate ground clutter point according to a distance value corresponding to each candidate ground clutter point in the range Doppler map and an installation height of the radar;

[0009] Calculating the pitch angle deviation corresponding to the radar based on the standard pitch angle corresponding to each candidate clutter point and the pitch angle detected by the radar;

[0010] The pitch angle of the radar is calibrated according to the relationship between the pitch angle deviation and the preset deviation range.

[0011] Optionally, the step of determining a range dimension range and a velocity dimension range in the range Doppler map to obtain a ground clutter area includes:

[0012] Determining, in the range Doppler map, an upper boundary and a lower boundary of a ground clutter region corresponding to a speed dimension according to a speed of the vehicle, a preset number of extended index units, and a speed resolution of the radar;

[0013] Based on the distance value corresponding to the nearest stationary obstacle to the radar in the range Doppler map and the lower limit of the radar's elevation detection range, determine the left boundary and the right boundary of the ground clutter area in the range Doppler map corresponding to the range dimension;

[0014] An area consisting of the upper boundary, the lower boundary, the left boundary and the right boundary is determined as the ground clutter area.

[0015] Optionally, the step of determining the upper boundary and the lower boundary of the ground clutter area corresponding to the speed dimension in the range Doppler map according to the speed of the vehicle, the preset number of extended index units, and the speed resolution of the radar includes:

[0016] Acquiring the speed of the vehicle when the radar collects the echo signal;

[0017] Calculating a quotient between the vehicle speed and the speed resolution of the radar, and rounding the quotient to obtain a speed index;

[0018] Calculating a multiplication value between a preset number of extended index units and a velocity resolution of the radar to obtain an extended value;

[0019] The product of the velocity index and the velocity resolution is taken as the midpoint, and the difference between the value of the midpoint and the two values ​​of the extension value are respectively used as the left boundary and the right boundary of the ground clutter area corresponding to the velocity dimension.

[0020] Optionally, the step of determining, in the range Doppler map, a left boundary and a right boundary corresponding to the range dimension of the ground clutter area based on a distance value corresponding to the stationary obstacle closest to the radar in the range Doppler map and a lower limit of the radar elevation detection range, comprises:

[0021] Determine a distance value corresponding to the stationary obstacle closest to the radar in the range Doppler map as the right boundary of the ground clutter area corresponding to the range dimension;

[0022] Based on the lower limit of the radar's elevation-dimension detection range, a left boundary of the ground clutter region corresponding to the distance dimension is determined.

[0023] Optionally, the step of selecting a plurality of candidate ground clutter points from the ground clutter area includes:

[0024] A preset number of ground clutter points with the highest corresponding signal-to-noise ratios are selected from the ground clutter area as candidate ground clutter points.

[0025] Optionally, the step of calculating the pitch angle deviation corresponding to the radar based on the standard pitch angle corresponding to each candidate ground clutter point and the pitch angle detected by the radar includes:

[0026] Based on the signal-to-noise ratio, azimuth and standard pitch angle corresponding to the candidate ground clutter points, the candidate ground clutter points are screened to obtain target ground clutter points, wherein the azimuth is the angle between the line connecting the ground point corresponding to the ground clutter point in the physical world and the radar and the normal line of the radar;

[0027] When the number of the target ground clutter points reaches a preset number, calculating the standard deviation of the standard pitch angles corresponding to the preset number of target ground clutter points;

[0028] If the standard deviation is less than a preset threshold, the average value of the standard pitch angles corresponding to the preset number of target ground clutter points is calculated, and the difference between the average value and the pitch angle detected by the radar is used as the pitch angle deviation corresponding to the radar.

[0029] Optionally, the step of calculating the standard pitch angle of the radar corresponding to each candidate ground clutter point according to the distance value corresponding to each candidate ground clutter point in the range Doppler map and the installation height of the radar comprises:

[0030] Calculate the multiplication value between the distance index corresponding to each candidate ground clutter point in the range Doppler map and the distance resolution of the radar to obtain the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar;

[0031] According to the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar and the installation height of the radar, the standard pitch angle of the radar corresponding to each candidate ground clutter point is calculated according to the inverse sine function.

[0032] Optionally, before the step of obtaining a range Doppler map obtained by processing the echo signal collected by the radar, the method further includes:

[0033] Obtaining the acceleration and turning radius of the vehicle;

[0034] If the acceleration is within a preset acceleration range and the turning radius is greater than a preset radius, it is determined that the driving state of the vehicle satisfies a uniform speed straight-line driving condition.

[0035] Optionally, before the step of obtaining a range Doppler map obtained by processing the echo signal collected by the radar, the method further includes:

[0036] Obtain slope recognition results corresponding to multiple frames, and determine whether the number of frames of the current frame obtained is greater than a preset window length each time a slope recognition result corresponding to a frame is obtained;

[0037] If the frame number of the current frame is not greater than the preset window length, determine the index of the current frame as the frame number of the current frame, and determine the slope recognition result corresponding to the index of the current frame as the slope recognition result corresponding to the current frame; and increase the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs by one;

[0038] If the frame number of the current frame is greater than the preset window length, determine the index of the current frame based on the frame number of the current frame and the preset window length; reduce the count corresponding to the slope type to which the slope recognition result corresponding to the index of the current frame belongs by one; replace the slope recognition result corresponding to the index of the current frame with the slope recognition result corresponding to the current frame; increase the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs by one; and determine that the current slope type is the slope type with the highest corresponding count.

[0039] In a second aspect, an embodiment of the present application provides a radar pitch angle calibration device, wherein the radar is installed on a vehicle, and the radar is used to transmit a radar signal to the outside world and receive an echo signal reflected by the outside world, and the device includes:

[0040] a range Doppler map acquisition module, used to acquire a range Doppler map obtained by processing the echo signal collected by the radar, wherein the echo signal is collected by the radar when the driving state of the vehicle meets a preset calibration condition, the preset calibration condition includes a preset uniform straight-line driving condition and a preset flat road surface condition, and the range Doppler map is a two-dimensional relationship diagram between distance and speed;

[0041] a ground clutter region determination module, configured to determine a range dimension range and a speed dimension range in the range Doppler map to obtain a ground clutter region, wherein the ground clutter region is a region corresponding to an echo signal reflected from the ground collected by the radar when the driving state of the vehicle satisfies the preset calibration condition;

[0042] a standard pitch angle calculation module, configured to select a plurality of candidate ground clutter points from the ground clutter area, and calculate a standard pitch angle of the radar corresponding to each candidate ground clutter point according to a distance value corresponding to each candidate ground clutter point in the range Doppler map and an installation height of the radar;

[0043] A pitch angle deviation calculation module, used to calculate the pitch angle deviation corresponding to the radar based on the standard pitch angle corresponding to each candidate clutter point and the pitch angle detected by the radar;

[0044] The pitch angle calibration module is used to calibrate the pitch angle of the radar according to the relationship between the pitch angle deviation and a preset deviation range.

[0045] Optionally, the ground clutter region determination module includes:

[0046] A first boundary determination submodule, configured to determine an upper boundary and a lower boundary of a ground clutter region corresponding to a velocity dimension in the range Doppler map according to a vehicle speed of the vehicle, a preset number of extended index units, and a velocity resolution of the radar;

[0047] A second boundary determination submodule is used to determine, in the range Doppler map, a left boundary and a right boundary corresponding to the ground clutter area in the range dimension based on a distance value corresponding to the stationary obstacle closest to the radar in the range Doppler map and a lower limit of the radar's elevation detection range;

[0048] The ground clutter region determination submodule is used to determine the region consisting of the upper boundary, the lower boundary, the left boundary and the right boundary as the ground clutter region.

[0049] Optionally, the first boundary determination submodule includes:

[0050] A vehicle speed acquisition unit, used to acquire the vehicle speed when the radar collects the echo signal;

[0051] a speed index determination unit, configured to calculate a quotient between the vehicle speed and the speed resolution of the radar, and round the quotient to obtain a speed index;

[0052] An extension value calculation unit, used to calculate a multiplication value between a preset number of extension index units and a velocity resolution of the radar to obtain an extension value;

[0053] The first boundary determination unit is used to use the product of the velocity index and the velocity resolution as the midpoint, and the difference between the value of the midpoint and the two values ​​of the extended value as the left boundary and the right boundary of the ground clutter area corresponding to the velocity dimension.

[0054] Optionally, the second boundary determination submodule includes:

[0055] A second boundary determination unit is used to determine a distance value corresponding to a stationary obstacle closest to the radar in the range Doppler map as a right boundary of the ground clutter area corresponding to the range dimension;

[0056] The third boundary determination unit is used to determine the left boundary of the ground clutter area corresponding to the distance dimension based on the lower limit of the radar pitch dimension detection range.

[0057] Optionally, the standard pitch angle calculation module includes:

[0058] The candidate ground clutter point selection submodule is used to select a preset number of ground clutter points with the highest corresponding signal-to-noise ratio from the ground clutter area as candidate ground clutter points.

[0059] Optionally, the pitch angle deviation calculation module includes:

[0060] A ground clutter point screening submodule, configured to screen the candidate ground clutter points based on the signal-to-noise ratio, azimuth, and standard pitch angle corresponding to the candidate ground clutter points to obtain target ground clutter points, wherein the azimuth is the angle between the line connecting the ground point corresponding to the ground clutter point in the physical world and the radar and the normal to the radar;

[0061] A standard deviation calculation submodule, configured to calculate the standard deviation of the standard pitch angles corresponding to the preset number of target ground clutter points when the number of the target ground clutter points reaches a preset number;

[0062] The pitch angle deviation determination submodule is used to calculate the average value of the standard pitch angles corresponding to the preset number of target ground clutter points if the standard deviation is less than a preset threshold, and use the difference between the average value and the pitch angle detected by the radar as the pitch angle deviation corresponding to the radar.

[0063] Optionally, the standard pitch angle calculation module includes:

[0064] A distance calculation submodule, used to calculate the multiplication value between the distance index corresponding to each candidate ground clutter point in the range Doppler map and the distance resolution of the radar, and obtain the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar;

[0065] The standard pitch angle calculation submodule is used to calculate the standard pitch angle of the radar corresponding to each candidate ground clutter point according to the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar and the installation height of the radar according to the inverse sine function.

[0066] Optionally, the device further comprises:

[0067] A vehicle parameter acquisition module, used for acquiring the acceleration and turning radius of the vehicle before the step of acquiring the range Doppler map obtained by processing the echo signal collected by the radar;

[0068] The condition determination module is used to determine that the driving state of the vehicle meets the uniform speed straight driving condition if the acceleration is within a preset acceleration range and the turning radius is greater than a preset radius.

[0069] Optionally, the device further comprises:

[0070] The recognition result acquisition module is used to obtain the slope recognition results corresponding to multiple frames before the step of obtaining the range Doppler map obtained by processing the echo signal collected by the radar, and each time the slope recognition result corresponding to a frame is obtained, determine whether the frame number of the current frame obtained is greater than the preset window length;

[0071] A counting and statistics module is used to determine, if the number of frames of the current frame is not greater than the preset window length, the index of the current frame as the number of frames of the current frame, and determine the slope recognition result corresponding to the index of the current frame as the slope recognition result corresponding to the current frame; and increase the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs by one;

[0072] A slope type determination module is used to determine the index of the current frame based on the frame number of the current frame and the preset window length if the frame number of the current frame is greater than the preset window length; reduce the count corresponding to the slope type to which the slope recognition result corresponding to the index of the current frame belongs by one; replace the slope recognition result corresponding to the index of the current frame with the slope recognition result corresponding to the current frame; increase the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs by one; and determine that the current slope type is the slope type with the highest corresponding count.

[0073] In a third aspect, an embodiment of the present application provides an electronic device, including:

[0074] Memory, used to store computer programs;

[0075] The processor is used to implement any method described in the first aspect when executing a program stored in the memory.

[0076] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, any method described in the first aspect is implemented.

[0077] Beneficial effects of the embodiments of the present application:

[0078] In the solution provided by the embodiment of the present application, the electronic device can obtain a range Doppler map obtained by processing the echo signal collected by the radar, wherein the echo signal is collected by the radar when the driving state of the vehicle meets the preset calibration conditions, the preset calibration conditions include preset uniform straight driving conditions and preset road flatness conditions, and the range Doppler map is a two-dimensional relationship diagram between distance and speed; determine the distance dimension range and the speed dimension range in the range Doppler map to obtain a ground clutter area, wherein the ground clutter area is the area corresponding to the echo signal reflected by the ground collected by the radar when the driving state of the vehicle meets the preset calibration conditions; select multiple candidate ground clutter points from the ground clutter area, and calculate the standard pitch angle of the radar corresponding to each candidate ground clutter point according to the distance value corresponding to each candidate ground clutter point in the range Doppler map and the installation height of the radar; calculate the pitch angle deviation corresponding to the radar based on the standard pitch angle corresponding to each candidate ground clutter point and the pitch angle detected by the radar; calibrate the pitch angle of the radar according to the relationship between the pitch angle deviation and the preset deviation range. After sending out a signal, the radar will receive an echo signal from the ground, i.e., ground clutter. In the range Doppler map obtained by processing the radar echo signal, there is a ground clutter area, and the ground clutter points in the ground clutter area correspond to ground points in the physical world. Through the distance value corresponding to the ground clutter point in the range Doppler map and the range resolution of the radar, the distance between the ground point corresponding to the ground clutter point and the radar can be calculated. Combined with the installation height of the radar, the standard pitch angle corresponding to the radar can be calculated. Since the range Doppler map is obtained by processing the echo signal collected by the radar when the vehicle meets the conditions of uniform straight driving and flat road conditions, the standard pitch angle is the pitch angle when there is no installation error of the radar, and the pitch angle detected by the radar is the pitch angle when there is an installation error of the radar. Therefore, the difference between the standard pitch angle and the pitch angle detected by the radar can be used to determine the pitch angle deviation corresponding to the radar, and then calibrate the pitch angle of the radar. In this way, the safety hazards caused by the installation error of the vehicle-mounted radar in the pitch direction can be avoided. And the calibration speed is fast, and the user can calibrate automatically in real time while driving, without having to complete the calibration before driving, so the calibration process is relatively simple. Of course, implementing any product or method of the present application does not necessarily need to achieve all the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0080] Figure 1 A flow chart of a radar elevation angle calibration method provided in an embodiment of the present application;

[0081] Figure 2 for Figure 1 A specific flow chart of step S102 in the illustrated embodiment;

[0082] Figure 3 Based on Figure 1 A schematic diagram of the geometric relationship between the vehicle and the target of the illustrated embodiment;

[0083] Figure 4 for Figure 2 A specific flow chart of step S201 in the illustrated embodiment;

[0084] Figure 5 for Figure 2 A specific flow chart of step S202 in the illustrated embodiment;

[0085] Figure 6(a) is based on Figure 1 A schematic diagram of a vehicle driving trajectory of the illustrated embodiment;

[0086] Figure 6(b) is based on Figure 1 A schematic diagram of a range Doppler map of the illustrated embodiment;

[0087] Figure 7(a) is based on Figure 1 A schematic diagram of a road scene captured by a vehicle-mounted camera in the illustrated embodiment;

[0088] Figure 7(b) is based on Figure 1 A schematic diagram of a range Doppler map of the illustrated embodiment;

[0089] Figure 8 for Figure 1 A specific flow chart of step S104 in the illustrated embodiment;

[0090] Fig. 9 for Figure 1 A specific flow chart of step S103 in the illustrated embodiment;

[0091] Fig.10 Based on Figure 1 A flow chart of determining whether a uniform speed straight-line driving condition is met in the illustrated embodiment;

[0092] Fig.11 Based on Figure 1 A schematic diagram of vehicle travel in the illustrated embodiment;

[0093] Fig.12 Based on Figure 1 A flow chart of determining the current slope type in the illustrated embodiment;

[0094] Fig.13 Based on Figure 1 A schematic diagram of the force analysis of a vehicle on a slope according to the embodiment shown;

[0095] Fig.14 for Figure 1 A specific flow chart of step S105 in the illustrated embodiment;

[0096] Fig.15 Based on Figure 1 A flow chart of a method for determining radar calibration results of the illustrated embodiment;

[0097] Fig.16 A schematic diagram of the structure of a radar elevation angle calibration device provided in an embodiment of the present application;

[0098] Fig.17 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0099] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field based on the present application belong to the scope of protection of the present application.

[0100] In order to achieve the pitch angle calibration of the vehicle-mounted radar and avoid the safety hazards caused by the installation error of the vehicle-mounted radar in the pitch direction, the embodiment of the present application provides a radar pitch angle calibration method, device, electronic device, computer readable storage medium and computer program product. The following first introduces a radar pitch angle calibration method provided by the embodiment of the present application.

[0101] The radar pitch angle calibration method provided in the embodiment of the present application can be applied to any electronic device that needs to calibrate the pitch angle of the radar, for example, it can be a control device, a processing device, a calibration device, etc., which is not specifically limited here. For the sake of clarity, it is subsequently referred to as an electronic device in this article.

[0102] like Figure 1As shown, a radar pitch angle calibration method is provided, wherein the radar is installed on a vehicle, and the radar is used to transmit radar signals to the outside world and receive echo signals reflected by the outside world, and the method comprises:

[0103] S101, obtaining a range Doppler map obtained by processing the echo signal collected by the radar;

[0104] Among them, the echo signal is collected by the radar when the driving state of the vehicle meets the preset calibration conditions, the preset calibration conditions include preset uniform straight driving conditions and preset flat road conditions, and the range Doppler map is a two-dimensional relationship diagram between distance and speed.

[0105] S102, determining a range dimension range and a velocity dimension range in the range Doppler map to obtain a ground clutter region;

[0106] The ground clutter area is an area corresponding to the echo signal reflected from the ground collected by the radar when the driving state of the vehicle meets the preset calibration condition.

[0107] S103, selecting a plurality of candidate ground clutter points from the ground clutter area, and calculating a standard pitch angle of the radar corresponding to each candidate ground clutter point according to a distance value corresponding to each candidate ground clutter point in the range Doppler map and an installation height of the radar;

[0108] S104, calculating the pitch angle deviation corresponding to the radar based on the standard pitch angle corresponding to each candidate clutter point and the pitch angle detected by the radar;

[0109] S105: calibrate the pitch angle of the radar according to the relationship between the pitch angle deviation and a preset deviation range.

[0110] It can be seen that in the embodiment of the present application, the electronic device can obtain a range Doppler map obtained by processing the echo signal collected by the radar, wherein the echo signal is collected by the radar when the driving state of the vehicle meets the preset calibration conditions, the preset calibration conditions include preset uniform straight driving conditions and preset road flatness conditions, and the range Doppler map is a two-dimensional relationship diagram between distance and speed; determine the distance dimension range and the speed dimension range in the range Doppler map to obtain a ground clutter area, wherein the ground clutter area is the area corresponding to the echo signal reflected by the ground collected by the radar when the driving state of the vehicle meets the preset calibration conditions; select multiple candidate ground clutter points from the ground clutter area, and calculate the standard pitch angle of the radar corresponding to each candidate ground clutter point according to the distance value corresponding to each candidate ground clutter point in the range Doppler map and the installation height of the radar; calculate the pitch angle deviation corresponding to the radar based on the standard pitch angle corresponding to each candidate ground clutter point and the pitch angle detected by the radar; calibrate the pitch angle of the radar according to the relationship between the pitch angle deviation and the preset deviation range. After sending out a signal, the radar will receive an echo signal from the ground, i.e., ground clutter. In the range Doppler map obtained by processing the radar echo signal, there is a ground clutter area, and the ground clutter points in the ground clutter area correspond to ground points in the physical world. Through the distance value corresponding to the ground clutter point in the range Doppler map and the range resolution of the radar, the distance between the ground point corresponding to the ground clutter point and the radar can be calculated. Combined with the installation height of the radar, the standard pitch angle corresponding to the radar can be calculated. Since the range Doppler map is obtained by processing the echo signal collected by the radar when the vehicle meets the conditions of uniform straight driving and flat road conditions, the standard pitch angle is the pitch angle when there is no installation error of the radar, and the pitch angle detected by the radar is the pitch angle when there is an installation error of the radar. Therefore, the difference between the standard pitch angle and the pitch angle detected by the radar can be used to determine the pitch angle deviation corresponding to the radar, and then calibrate the pitch angle of the radar. In this way, the safety hazards caused by the installation error of the vehicle-mounted radar in the pitch direction can be avoided. Moreover, the calibration speed is relatively fast, and the user can automatically calibrate in real time while driving, without having to complete the calibration before driving, so the calibration process is relatively simple.

[0111] When the driving state of the vehicle meets the preset calibration conditions, the radar can transmit a signal and collect the echo signal. In step S101, the electronic device can obtain a range Doppler map (Range-Doppler, RD map) obtained by processing the above echo signal. The preset calibration conditions may include a preset uniform straight-line driving condition and a preset flat road surface condition.

[0112] The above range Doppler map is a two-dimensional relationship map between distance and speed, which can be used to reflect the distance between the target and the radar and the speed of the target. The range Doppler map can be obtained by the electronic device after processing the echo signal, or it can be obtained by the electronic device from other devices after other devices process the echo signal, which is reasonable.

[0113] The above radar may be a 4D millimeter wave radar (4D High Resolution Radar), which is a millimeter wave radar system with high precision and high resolution, which can obtain the position information of the target in real time, specifically the distance, speed, azimuth angle, pitch angle, etc. of the target. It can also estimate the shape information of the target, for example, determine the length, width, etc. of the target.

[0114] The range Doppler map includes a ground clutter region, where the ground clutter is the radar echo reflected from the ground. The ground clutter region is the region corresponding to the echo signal reflected from the ground collected by the radar when the driving state of the vehicle meets the preset calibration conditions. The intensity and characteristics of the ground clutter depend on many factors, such as radar frequency, polarization mode, topography, material and distribution of ground objects, etc. In step S102, the electronic device can determine the range dimension range and the speed dimension range in the range Doppler map to obtain the ground clutter region.

[0115] Since ground clutter is the radar echo reflected by the ground, the ground clutter points included in the ground clutter area correspond to the ground points in the physical world. When the vehicle's driving state meets the preset road flatness condition, the ground can be considered to be horizontal. Then the angle between the line between the ground point in the physical world and the radar and the ground is the pitch angle of the radar when there is no installation error.

[0116] In step S103, the electronic device may select multiple candidate ground clutter points from the ground clutter area, each candidate ground clutter point corresponding to a ground point in the physical world. Next, the electronic device may calculate the standard pitch angle of the radar corresponding to each candidate ground clutter point according to the distance value corresponding to each candidate ground clutter point in the range Doppler map and the installation height of the radar. The standard pitch angle is the pitch angle of the radar when there is no installation error.

[0117] Since the pitch angle detected by the radar is the pitch angle when there is an installation error, and the standard pitch angle is the pitch angle when the radar does not have an installation error, the pitch angle deviation corresponding to the radar can be calculated based on the standard pitch angle corresponding to each candidate clutter point and the pitch angle detected by the radar, that is, step S104 is executed.

[0118] When the pitch angle deviation is small, it means that the radar is not tilted much, and the pitch angle deviation can be used to compensate for the radar's pitch angle. If the pitch angle deviation is large, it means that the radar is tilted much, and it is likely that the radar's pitch angle cannot be calibrated by compensating for the pitch angle deviation. In this case, manual intervention is usually required to manually adjust the radar's angle.

[0119] In order to determine the deflection degree of the radar, and then determine whether the radar can be calibrated by compensating for the pitch angle deviation, the electronic device can calibrate the pitch angle of the radar according to the relationship between the pitch angle deviation and the preset deviation range, that is, execute step S105. Specifically, if the pitch angle deviation is within the preset deviation range, it can be determined that the deflection degree of the radar is small, and then the radar is calibrated by the pitch angle deviation. Among them, the preset deviation range can be set according to actual needs, and can be [-5°, 5°], [-8°, 8°], and so on.

[0120] It can be seen that after the radar sends out a signal, it will receive an echo signal from the ground, that is, ground clutter. In the range Doppler map obtained by processing the radar echo signal, there is a ground clutter area, and the ground clutter points in the ground clutter area correspond to ground points in the physical world. Through the distance value corresponding to the ground clutter point in the range Doppler map and the range resolution of the radar, the distance between the ground point corresponding to the ground clutter point and the radar can be calculated, and then combined with the installation height of the radar, the standard pitch angle corresponding to the radar can be calculated. Since the range Doppler map is obtained by processing the echo signal collected by the radar when the vehicle meets the conditions of uniform straight driving and flat road conditions, the standard pitch angle is the pitch angle when there is no installation error of the radar, and the pitch angle detected by the radar is the pitch angle when there is an installation error of the radar. Therefore, the difference between the standard pitch angle and the pitch angle detected by the radar can be used to determine the pitch angle deviation corresponding to the radar, and then calibrate the pitch angle of the radar. In this way, the safety hazards caused by the installation error of the vehicle-mounted radar in the pitch direction can be avoided. Moreover, the calibration speed is relatively fast, and the user can automatically calibrate in real time while driving, without having to complete the calibration before driving, so the calibration process is relatively simple.

[0121] As an implementation method of the present application, Figure 2 As shown, the above step of determining the range dimension range and the velocity dimension range in the range Doppler map to obtain the ground clutter area may include:

[0122] S201, determining an upper boundary and a lower boundary of a ground clutter region corresponding to a speed dimension in the range Doppler map according to a speed of the vehicle, a preset number of extended index units, and a speed resolution of the radar;

[0123] The velocity value in the range Doppler map reflects the radial velocity of the target relative to the radar. When the target is a ground point, the radial velocity of the ground point relative to the radar can be determined by the vehicle speed. In order to make the range dimension range cover a sufficient number of ground clutter points, the number of extended index units can be pre-set to expand the span of the range dimension range. In this way, the electronic device can determine the upper and lower boundaries of the ground clutter area in the speed dimension in the range Doppler map according to the vehicle speed, the preset number of extended index units and the speed resolution of the radar.

[0124] S202, determining, in the range Doppler map, a left boundary and a right boundary of the ground clutter region corresponding to the range dimension based on a distance value corresponding to the stationary obstacle closest to the radar in the range Doppler map and a lower limit of the radar's elevation detection range;

[0125] In the range Doppler diagram, the Doppler of the target can be expressed as d = Vcosθ. Where V is the speed of the vehicle and θ is the angle between the target and the radar normal. For example, the schematic diagram of the geometric relationship between the vehicle and the target can be as follows: Figure 3 As shown, Figure 3 It is a top view, assuming that the radar is installed at the bumper in front of the vehicle 301, and the vehicle 301 is moving forward at a speed V, then the direction of the radar normal is the same as the speed V. There is a target 302 in front of the left side of the vehicle 301, and the angle between the line between the target 302 and the vehicle and the radar normal is θ, then the Doppler d of the target 302 can be determined as d=Vcosθ.

[0126] When θ = 0°, the ground point is located directly in front of the radar, and the Doppler of the ground point is d = V. When θ = 90°, the Doppler value is 0, indicating that the stationary obstacle is located at the same level as the radar. In the distance Doppler diagram, the distance value corresponding to the Doppler value of 0 is the distance between the stationary obstacle closest to the radar and the radar.

[0127] On the one hand, since the energy of ground clutter is weak, the ground clutter area is located closer to the stationary obstacle in the range Doppler map. If you choose an area farther away than the stationary obstacle, you may face the risk of weak signal energy and incorrect target angle resolution. In other words, the energy of the stationary obstacle may cover the energy of the ground point, making it impossible to accurately determine the angle between the radar normal and the ground point. Therefore, the right boundary corresponding to the range dimension can be determined based on the distance of the stationary obstacle closest to the radar.

[0128] On the other hand, although the elevation angle of the radar may change, the installation height of the radar is usually fixed. If you choose an area that is close to the radar, the standard elevation angle corresponding to the radar will be relatively large. In this case, it may exceed the lower limit of the radar's elevation detection range, resulting in inaccurate elevation angle detection by the radar. Therefore, the left boundary of the ground clutter area corresponding to the distance dimension can be determined based on the lower limit of the radar's elevation detection range. Among them, the lower limit of the radar's elevation detection range is the lower boundary of the radar's elevation detection range.

[0129] S203: Determine an area consisting of the upper boundary, the lower boundary, the left boundary, and the right boundary as the ground clutter area.

[0130] After determining the left boundary, right boundary, upper boundary and lower boundary of the ground clutter region corresponding to the velocity dimension, the electronic device can determine the region composed of the left boundary, the right boundary, the upper boundary and the lower boundary as the ground clutter region.

[0131] It can be seen that in the embodiment of the present application, the electronic device can determine the upper and lower boundaries of the ground clutter area in the speed dimension in the range Doppler map according to the vehicle speed, the preset number of extended index units, and the speed resolution of the radar; determine the left and right boundaries of the ground clutter area in the distance dimension in the range Doppler map based on the distance value corresponding to the nearest stationary obstacle to the radar in the range Doppler map and the lower limit of the radar pitch dimension detection range; determine the area composed of the upper boundary, lower boundary, left boundary, and right boundary as the ground clutter area. In this way, the electronic device can determine the left boundary, right boundary, upper boundary, and lower boundary corresponding to the ground clutter area from the speed dimension and the distance dimension, respectively, and then quickly and accurately determine the ground clutter area.

[0132] As an implementation method of the present application, Figure 4 As shown, the step of determining the upper boundary and the lower boundary of the ground clutter area corresponding to the speed dimension in the range Doppler map according to the speed of the vehicle, the preset number of extended index units and the speed resolution of the radar may include:

[0133] S401, obtaining the speed of the vehicle when the radar collects the echo signal;

[0134] Since the Doppler corresponding to the ground point is related to the relative radial velocity between the ground point and the radar, the electronic device can obtain the vehicle speed when the radar collects the echo signal.

[0135] S402, calculating a quotient between the vehicle speed and the speed resolution of the radar, and rounding the quotient to obtain a speed index;

[0136] After determining the speed of the vehicle, the electronic device can calculate the quotient between the speed and the speed resolution of the radar, and round the quotient to obtain a speed index corresponding to the speed. The rounding operation can be rounding up or rounding down, which is not specifically limited here.

[0137] Assuming the vehicle speed is V and the speed resolution of the radar is ΔV, the quotient between the vehicle speed and the speed resolution is V / ΔV. Next, the quotient can be rounded up to get the speed index For example, assuming that the vehicle speed is 8 m / s and the speed resolution of the radar is 0.6 m / s, the quotient between the vehicle speed and the speed resolution can be calculated to be 13.33. By rounding up the quotient, the speed index corresponding to the vehicle speed can be obtained to be 14.

[0138] S403, calculating a multiplication value between a preset number of extended index units and a velocity resolution of the radar to obtain an extended value;

[0139] The electronic device can calculate the multiplication value between the preset number of extended index units and the speed resolution of the radar to obtain the extended value. The number of extended index units can be determined in advance according to the radar parameters. For example, the number of extended index units can be 5, 6, 7, and so on.

[0140] S404, taking the product of the velocity index and the velocity resolution as the midpoint, and taking the difference between the midpoint and the two values ​​of the extended value as the left boundary and the right boundary of the ground clutter region corresponding to the velocity dimension.

[0141] In order to determine the left boundary and the right boundary of the ground clutter region corresponding to the velocity dimension, the electronic device can calculate the multiplication value between the velocity index and the velocity resolution, take the multiplication value as the midpoint, and take the difference between the midpoint value and the two values ​​of the extension value as the left boundary and the right boundary of the ground clutter region corresponding to the velocity dimension. Specifically, the electronic device can take the difference between the midpoint and the extension value as the left boundary, and take the sum of the midpoint and the extension value as the right boundary.

[0142] Assume the velocity index is V id , the number of extended index units is n, then the index range corresponding to the ground clutter area can be [V id -n,V id +n]. Assuming that the velocity resolution of the radar is ΔV, the left boundary of the ground clutter area can be (V id -n)×ΔV, the right boundary of the ground clutter area can be (V id +n)×ΔV.

[0143] It can be seen that in the embodiment of the present application, the electronic device can obtain the speed of the vehicle when the radar collects the echo signal; calculate the quotient between the speed and the speed resolution of the radar, round the quotient to obtain the speed index; calculate the multiplication value between the preset number of extended index units and the speed resolution of the radar to obtain the extended value; take the multiplication value between the speed index and the speed resolution as the midpoint, and take the difference between the value of the midpoint as the two values ​​of the extended value as the left and right boundaries of the ground clutter area corresponding to the speed dimension. Since the Doppler of the ground point is related to the vehicle speed, the electronic device can calculate the speed index through the vehicle speed and the speed resolution of the radar. Furthermore, according to the speed index, the number of extended index units and the speed resolution of the radar, the left and right boundaries of the ground clutter area corresponding to the speed dimension are determined. In this way, the left and right boundaries corresponding to the ground clutter area can be quickly and accurately determined.

[0144] As an implementation method of the present application, Figure 5 As shown, the step of determining the left boundary and the right boundary of the ground clutter area corresponding to the range dimension in the range Doppler map based on the distance value corresponding to the nearest stationary obstacle to the radar in the range Doppler map and the lower limit of the radar elevation detection range may include:

[0145] S501, determining a distance value corresponding to the stationary obstacle closest to the radar in the range Doppler map as a right boundary of the ground clutter region corresponding to the range dimension;

[0146] In order to avoid the influence of the energy of the stationary obstacle on the energy of the ground clutter, a ground point whose distance to the radar is less than the distance to the nearest stationary obstacle to the radar can be selected. Therefore, the electronic device can determine the distance value corresponding to the nearest stationary obstacle to the radar in the range Doppler map, and use the distance value as the right boundary of the ground clutter area corresponding to the distance dimension.

[0147] S502: Determine a left boundary of the ground clutter area corresponding to the distance dimension based on the lower limit of the radar's elevation dimension detection range.

[0148] Assuming the radar is installed at a height of h and the distance between the radar and the ground point is R, then the standard pitch angle of the radar relative to the ground point is If the distance R between the radar and the ground point is small, then the standard elevation angle of the radar to the ground point is will be larger. In this case, the ground point may exceed the lower limit of the radar pitch dimension detection range, resulting in the radar being unable to accurately detect the pitch angle. Therefore, the electronic device can determine the left boundary of the ground clutter area corresponding to the distance dimension based on the lower limit of the radar pitch dimension detection range. In one embodiment, the electronic device can determine that the lower limit of the radar pitch dimension detection range is at the ground point corresponding to the ground, and then use the distance value corresponding to the ground point in the range Doppler map as the left boundary of the ground clutter area corresponding to the distance dimension.

[0149] Of course, the electronic device can also determine the index range corresponding to the ground clutter area in the distance dimension, and then determine the left and right boundaries corresponding to the ground clutter area in the distance dimension according to the index range and the distance resolution of the radar. For example, the ground clutter area corresponds to index unit 8-index unit 10 in the distance dimension, and the distance resolution is 0.2m, then it can be determined that the left and right boundaries corresponding to the ground clutter area in the distance dimension are 1.6m and 2m respectively. In this way, the ground clutter point of the specified index unit can be obtained in the distance dimension.

[0150] For example, a schematic diagram of a vehicle's driving trajectory can be shown in FIG6(a), where the horizontal axis is the vehicle's lateral position, ranging from -20 to 20, and the vertical axis is the vehicle's longitudinal position, ranging from 0 to 100, both in meters (m). The vehicle's starting point (X, Y) = (4, 0). As can be seen from FIG6(a), the vehicle starts from (4, 0) and travels in a straight line to (4, 100).

[0151] When the vehicle is traveling along the trajectory shown in Figure 6(a), the range Doppler graph obtained by processing the echo signal collected by the radar is shown in Figure 6(b). In Figure 6(b), the horizontal axis is the range, in meters (m), ranging from 0 to 80, and the vertical axis is the Doppler, in meters per second (m / s), ranging from 0 to 14. Limited by the detection range of the radar, as the distance value increases, the Doppler value approaches 10m / s.

[0152] In the range Doppler diagram, the coordinates of the target farthest from the radar are (X, Y) = (9.991, 95.28). Since the Doppler value of the stationary obstacle closest to the radar is 0, the coordinates of the stationary obstacle closest to the radar are (X, Y) = (4, 0), and the right boundary of the ground clutter area corresponding to the range dimension can be determined to be 4m. Through the lower limit of the radar's pitch dimension detection range, it can be determined that the left boundary of the ground clutter area corresponding to the range dimension is 0.5m.

[0153] Assume that the index range of the ground clutter region in the velocity dimension is [V id -5,V id +5], V id=63, then it can be determined that the indexes corresponding to the upper and lower boundaries are 58 and 68 respectively. Assuming that the velocity resolution of the radar is 0.16 m / s, it can be determined that the Doppler values ​​of the upper and lower boundaries are 9.28 m / s and 10.88 m / s respectively, and then the ground clutter area 601 is determined.

[0154] For example, a schematic diagram of a road scene captured by a vehicle-mounted camera may be shown in FIG. 7( a ), where “Frame cnt: 2” is displayed above the road scene, indicating that the index corresponding to the current road scene is 2, and the number 2001 displayed in the upper left corner of the road scene indicates that the current road scene is the 2001th frame.

[0155] A schematic diagram of a range Doppler map can be shown in FIG7(b), where the horizontal axis of the range Doppler map ranges from 0 to 200, and the vertical axis ranges from 0 to 50. The range Doppler map corresponds to the 2003rd frame of the road scene image, and the vehicle speed when the 2003rd frame is collected is 4.4833 m / s. The range Doppler map includes an obstacle area 701 corresponding to the stationary obstacle closest to the radar and a ground clutter area 702.

[0156] It can be seen that in the embodiment of the present application, the electronic device can determine the distance value corresponding to the nearest stationary obstacle to the radar in the range Doppler map as the right boundary of the ground clutter area in the distance dimension; based on the lower limit of the radar pitch dimension detection range, determine the left boundary of the ground clutter area in the distance dimension. Since the energy of the ground point is lower than that of the stationary obstacle, the right boundary corresponding to the distance dimension can be determined by the distance value corresponding to the nearest stationary obstacle to the radar in the range Doppler map. In order to prevent the radar from exceeding the limit of the radar detection range when detecting the ground point, the left boundary corresponding to the distance dimension can be determined based on the lower limit of the radar pitch dimension detection range. In this way, the left boundary and right boundary of the ground clutter area in the distance dimension can be quickly and accurately determined.

[0157] As an implementation manner of an embodiment of the present application, the above step of selecting a plurality of candidate ground clutter points from the ground clutter area may include:

[0158] A preset number of ground clutter points with the highest corresponding signal-to-noise ratios are selected from the ground clutter area as candidate ground clutter points.

[0159] Since the signal-to-noise ratio of the ground clutter point in the ground clutter area can reflect the echo strength of the ground point corresponding to the ground clutter point, and the echo strength is helpful for accurate positioning, the electronic device can select a preset number of ground clutter points with the highest corresponding signal-to-noise ratio from the ground clutter area as candidate ground clutter points. The preset number can be set according to actual needs. For example, it can be 2, 3, 4, etc.

[0160] In one embodiment, in order to save the amount of calculation, the electronic device can determine the maximum point and the second largest point of the signal-to-noise ratio from each distance dimension as candidate ground clutter points. For example, assuming that the ground clutter area corresponds to index unit 8 and index unit 9 in the distance dimension, index unit 8 includes ground clutter point 1-ground clutter point 5, index unit 9 includes ground clutter point 6-ground clutter point 10, and the signal-to-noise ratios corresponding to ground clutter point 1-ground clutter point 10 are 20dB, 13dB, 15dB, 14dB, 26dB, 22dB, 31dB, 14dB, 18dB, and 23dB, respectively. Then, ground clutter point 1 and ground clutter point 5 can be determined from index unit 8, and ground clutter point 7 and ground clutter point 10 can be determined from index unit 9.

[0161] It can be seen that in the embodiment of the present application, the electronic device can select a preset number of ground clutter points with the highest corresponding signal-to-noise ratio from the ground clutter area as candidate ground clutter points. Since the signal-to-noise ratio of the ground clutter point in the ground clutter area can reflect the echo strength of the ground point corresponding to the ground clutter point, and the echo strength is helpful for accurate positioning, the electronic device can select a preset number of ground clutter points with the highest corresponding signal-to-noise ratio from the ground clutter area as candidate ground clutter points. In this way, the amount of calculation can be saved, and the candidate ground clutter points can be quickly selected.

[0162] As an implementation method of the present application, Figure 8 As shown, the step of calculating the pitch angle deviation corresponding to the radar based on the standard pitch angle corresponding to each candidate clutter point and the pitch angle detected by the radar may include:

[0163] S801, screening the candidate ground clutter points based on the signal-to-noise ratio, azimuth angle, and standard pitch angle corresponding to the candidate ground clutter points to obtain target ground clutter points;

[0164] The signal-to-noise ratio corresponding to the ground clutter point can reflect the echo strength of the ground point corresponding to the ground clutter point, and the echo strength of the ground point is usually not too large. If the signal-to-noise ratio corresponding to the ground clutter point is too high, that is, the echo strength of the ground point corresponding to the ground clutter point is too large, it means that the ground point may actually be an obstacle. Therefore, the candidate ground clutter points can be screened based on the signal-to-noise ratio corresponding to the candidate ground clutter points.

[0165] The azimuth and standard elevation angle corresponding to the ground clutter point can reflect the position of the ground point corresponding to the ground clutter point within the radar detection range. If the position of the ground point corresponding to the ground clutter point is less offset relative to the normal direction of the radar, and the standard elevation angle corresponding to the ground clutter point is smaller, it means that the ground corresponding to the ground clutter point is in a suitable position within the radar detection range. Therefore, the electronic device can screen the candidate ground clutter points based on the signal-to-noise ratio, azimuth and standard elevation angle corresponding to the candidate ground clutter points to obtain the target ground clutter point. Among them, the azimuth is the angle between the line connecting the ground point corresponding to the ground clutter point in the physical world and the radar and the normal of the radar.

[0166] Specifically, in order to screen the candidate ground clutter points based on the signal-to-noise ratio, azimuth and standard pitch angle corresponding to the candidate ground clutter points, screening conditions corresponding to the signal-to-noise ratio, azimuth and standard pitch angle can be pre-set to screen the candidate ground clutter points that do not meet the screening conditions.

[0167] In one embodiment, the screening condition corresponding to the signal-to-noise ratio may be lower than a preset signal-to-noise ratio threshold, the screening condition corresponding to the azimuth angle may be within a preset azimuth angle range, and the screening condition corresponding to the elevation angle may be within a preset elevation angle range. For example, the preset signal-to-noise ratio threshold may be 20 dB, the preset azimuth angle range may be [-10°, 10°], and the preset elevation angle range may be [-15°, 15°].

[0168] S802, when the number of the target ground clutter points reaches a preset number, calculating the standard deviation of the standard pitch angles corresponding to the preset number of target ground clutter points; if the standard deviation is less than a preset threshold, executing step S803; if the standard deviation is not less than the preset threshold, executing step S804;

[0169] When the number of the target ground clutter points obtained by screening reaches a preset number, the electronic device can calculate the standard deviation of the standard pitch angles corresponding to the preset number of target ground clutter points, thereby determining whether the preset number of standard pitch angles are stable. The preset number can be set according to actual needs. For example, it can be 300, 400, 500, and so on.

[0170] If the standard deviation is less than the preset threshold, it means that the fluctuation range of the preset number of standard pitch angles at the data statistical level is small, and the standard pitch angle tends to a stable value, then the electronic device can execute step S803. If the standard deviation is not less than the preset threshold, it means that the fluctuation range of the preset number of standard pitch angles at the data statistical level is large, and the standard pitch angle is not stable, then the electronic device can execute step S804. The preset threshold can be set according to actual needs. For example, it can be 0.01, 0.03, 0.05, etc.

[0171] S803, calculating an average value of standard pitch angles corresponding to the preset number of target ground clutter points, and taking a difference between the average value and the pitch angle detected by the radar as a pitch angle deviation corresponding to the radar;

[0172] If the standard deviation is less than a preset threshold, the electronic device can calculate the average value of the standard pitch angles corresponding to a preset number of target ground clutter points, and use the difference between the average value and the pitch angle detected by the radar as the pitch angle deviation corresponding to the radar.

[0173] S804, discarding the currently obtained target ground clutter point, and returning to the step of obtaining a range Doppler map obtained by processing the echo signal collected by the radar.

[0174] If the standard deviation is not less than the preset threshold, the electronic device can discard the currently obtained target ground clutter point and return to the step of obtaining the range Doppler map obtained by processing the echo signal collected by the radar. In this way, the electronic device can re-acquire the candidate ground clutter point.

[0175] It can be seen that in the embodiment of the present application, the electronic device can screen the candidate ground clutter points based on the signal-to-noise ratio, azimuth and standard pitch angle corresponding to the candidate ground clutter points to obtain the target ground clutter points, wherein the azimuth is the angle between the line connecting the ground point corresponding to the ground clutter point in the physical world and the radar and the normal of the radar; when the number of target ground clutter points reaches a preset number, the standard deviation of the standard pitch angle corresponding to the preset number of target ground clutter points is calculated; if the standard deviation is less than the preset threshold, the average value of the standard pitch angle corresponding to the preset number of target ground clutter points is calculated, and the difference between the average value and the pitch angle detected by the radar is used as the pitch angle deviation corresponding to the radar. Since the number of target ground clutter points is large, the average standard pitch angle determined is close to the true value. Since the standard deviation of the standard pitch angle corresponding to the preset number of target ground clutter points is less than the preset threshold, the determined standard pitch angle is relatively stable. In this way, the pitch angle deviation corresponding to the radar can be determined quickly and accurately.

[0176] As an implementation method of the present application, Fig. 9 As shown, the step of calculating the standard pitch angle of the radar corresponding to each candidate ground clutter point according to the distance value corresponding to each candidate ground clutter point in the range Doppler map and the installation height of the radar may include:

[0177] S901, calculating the multiplication value between the distance index corresponding to each candidate ground clutter point in the range Doppler map and the distance resolution of the radar, to obtain the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar;

[0178] In order to obtain the standard pitch angle, a triangle can be constructed with the vertices being the radar, the radar's projection point on the ground, and the ground point corresponding to the candidate clutter point. The opposite side of the standard pitch angle is the distance between the radar and the ground, that is, the installation height of the radar, and the hypotenuse of the standard pitch angle is the distance between the ground point corresponding to the candidate clutter point and the radar. If the lengths of the opposite side and hypotenuse of the standard pitch angle are determined, the standard pitch angle can be calculated using the inverse sine function.

[0179] The electronic device can calculate the length of the hypotenuse. Specifically, the multiplication value between the distance value corresponding to each candidate clutter point in the range Doppler map and the range resolution of the radar can be calculated to obtain the distance between the ground point corresponding to each candidate clutter point in the physical world and the radar.

[0180] S902, calculating the standard elevation angle of the radar corresponding to each candidate ground clutter point according to the inverse sine function based on the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar and the installation height of the radar.

[0181] Since the installation height of the radar is predetermined, the lengths of the hypotenuse and the opposite side are known. The electronic device can calculate the standard pitch angle of the radar corresponding to each candidate ground clutter point according to the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar and the installation height of the radar according to the inverse sine function.

[0182] Assume that the installation height of the radar is h, and the distance index corresponding to the candidate clutter point is R id , the range resolution of the radar is ΔR, then the standard pitch angle of the radar to the ground point is If the radar detects a pitch angle of Then the pitch angle deviation

[0183] It can be seen that in the embodiment of the present application, the electronic device can calculate the multiplication value between the distance index corresponding to each candidate ground clutter point in the distance Doppler map and the distance resolution of the radar, and obtain the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar; according to the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar and the installation height of the radar, the standard pitch angle of the radar corresponding to each candidate ground clutter point is calculated according to the inverse sine function. Since only the distance between the ground point corresponding to the ground clutter point and the radar needs to be calculated in the process of calculating the standard pitch angle, the standard pitch angle can be obtained quickly and accurately.

[0184] As an implementation method of the present application, Fig.10 As shown, before the step of obtaining the range Doppler map obtained by processing the echo signal collected by the radar, the method may further include:

[0185] S1001, acquiring the acceleration and turning radius of the vehicle; if the acceleration is within a preset acceleration range and the turning radius is greater than the preset radius, executing step S1002; if the acceleration is not within the preset acceleration range or the turning radius is not greater than the preset radius, executing step S1003;

[0186] On the one hand, the vehicle needs to meet the uniform speed driving condition. The front of the vehicle is up when accelerating, and it is down when decelerating. The above two situations will interfere with the radar's road surface recognition and pitch angle calculation, so the vehicle needs to meet the uniform speed driving condition. Among them, the uniform speed driving condition can be that the acceleration of the vehicle is within a preset acceleration range. For example, the preset acceleration range can be [-0.2m / s 2 ,0.15m / s 2 ].

[0187] On the other hand, it is necessary to make the vehicle meet the straight-line driving condition. For example, a schematic diagram of vehicle driving can be as follows Fig.11 As shown, Fig.11 is a top view, the vehicle 1101 is turning, and the speed of the midpoint of the rear wheel of the vehicle 1101 is V ′ , the speed of the left front wheel of the vehicle is V, which can be orthogonally decomposed into V x and V y The Doppler of the target 1102 is d=Vcosβcosθ, where β is the yaw angle of the vehicle and θ is the azimuth angle of the target 1102 .

[0188] If θ=0, then the Doppler d of the target 1102 is Vcosβ, which is determined by the yaw angle and the vehicle speed. Since the yaw angle of the vehicle fluctuates greatly and the value of Vcosβ changes in real time when turning, it is not easy to obtain the ground clutter points in a fixed area, which is not conducive to the statistics of the pitch angle deviation. Therefore, it is necessary to make the vehicle meet the straight driving condition. Among them, the straight driving condition can be that the turning radius of the vehicle is greater than the preset radius. For example, the preset radius can be 1000m.

[0189] In addition, the above-mentioned preset calibration conditions may also include a vehicle speed condition. The vehicle speed condition may be that the vehicle speed is within a preset vehicle speed range. For example, the preset vehicle speed range may be [20km / h, 90km / h].

[0190] S1002, determining whether the driving state of the vehicle satisfies a uniform speed straight-line driving condition;

[0191] If the acceleration is within the preset acceleration range and the turning radius is greater than the preset radius, it can be determined that the driving state of the vehicle meets the uniform straight-line driving condition.

[0192] S1003, determining that the driving state of the vehicle does not satisfy a uniform speed straight-line driving condition.

[0193] If the acceleration is not within the preset acceleration range, or the turning radius is not greater than the preset radius, it can be determined that the driving state of the vehicle does not meet the uniform straight-line driving condition.

[0194] It can be seen that in the embodiment of the present application, the electronic device can obtain the acceleration and turning radius of the vehicle; if the acceleration is within the preset acceleration range and the turning radius is greater than the preset radius, it is determined that the driving state of the vehicle meets the uniform straight-line driving condition. The electronic device can determine whether the driving state of the vehicle meets the uniform straight-line driving condition through the acceleration and turning radius of the vehicle. This ensures that the pitch angle is calibrated when the driving state of the vehicle meets the uniform straight-line driving condition, and the standard pitch angle can be accurately determined.

[0195] As an implementation method of the present application, Fig.12 As shown, before the step of obtaining the range Doppler map obtained by processing the echo signal collected by the radar, the method may further include:

[0196] S1201, obtaining slope recognition results corresponding to multiple frames, and determining whether the number of frames of the current frame obtained is greater than a preset window length each time a slope recognition result corresponding to a frame is obtained; if the number of frames of the current frame is not greater than the preset window length, executing step S1202; if the number of frames of the current frame is greater than the preset window length, executing step S1204;

[0197] When the radar is calibrating the pitch angle, it is also necessary to ensure that the vehicle's driving state meets the preset road flatness condition. For example, the force analysis diagram of the vehicle on the slope can be as follows: Fig.13 As shown, the acceleration of vehicle 1301 along the slope is a1, which can be obtained by performing Kalman filtering on the vehicle's velocity. The slope is θ, the mass of the vehicle is m, and the gravity acceleration is g, then the gravity component of the vehicle along the slope can be determined to be mgsinθ. Assume that the acceleration sensor of the vehicle detects an acceleration of a he , then according to the force relationship, we can get a he =a1+gsinθ, and then we get the formula for calculating the slope θ: sinθ=(a he -a1) / g.

[0198] The electronic device can obtain the slope recognition results corresponding to multiple frames. The slope recognition results corresponding to the multiple frames can be determined based on the slopes corresponding to the multiple frames and the correspondence between the pre-constructed slope range and the slope type. Assuming that the slope of a frame belongs to the pre-constructed slope range corresponding to the flat type, for example, it can be [-1°, 2°], then it can be determined that the slope recognition result corresponding to the frame is a flat type. Assuming that the slope of a frame does not belong to the pre-constructed slope range corresponding to the flat type, then it can be determined that the slope recognition result corresponding to the frame is a rugged type.

[0199] In addition, the slope can also be used to determine whether the slope is uphill or downhill. When the slope is greater than the preset slope, the slope can be determined to be uphill; when the slope is less than the preset slope, the slope can be determined to be downhill. The preset slope can be set according to actual needs. For example, it can be 2°, 3°, 4°, and so on.

[0200] Since the data is volatile, in order to accurately determine the slope type, the electronic device can perform smoothing on the slope recognition results corresponding to multiple frames to obtain the slope type. In step S1201, the electronic device can obtain the slope recognition results corresponding to multiple frames, and each time the slope recognition results corresponding to a frame are obtained, it is determined whether the number of frames of the current frame obtained is greater than the preset window length, that is, it is determined that frame<=windowSize. Among them, frame is the number of frames of the current frame, and windowSize is the preset window length, which can be 32.

[0201] S1202, determining that the index of the current frame is the frame number of the current frame, and determining that the slope recognition result corresponding to the index of the current frame is the slope recognition result corresponding to the current frame;

[0202] If the number of frames of the frame is not greater than the preset window length, the electronic device may determine that the index of the frame is the number of frames of the frame, that is, index=frame, where index is the index of the type storage array.

[0203] Next, the electronic device can determine that the slope recognition result corresponding to the index of the frame is the slope recognition result corresponding to the frame, that is, typeArray[index]=slopeFlag, where typeArray is a sequence storing multiple frame recognition results, and slopeFlag is a temporary slope recognition result, that is, the slope recognition result corresponding to the current frame.

[0204] S1203, adding one to the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs;

[0205] In order to count the slope recognition results corresponding to multiple frames, the slope recognition results corresponding to each slope type can be counted. After obtaining the slope recognition result corresponding to the current frame, the electronic device can add one to the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs, that is, typeNum[slopeFlag]++.

[0206] In one embodiment, since the number of frames currently acquired is less than the preset window length, the number of slope recognition results acquired is small and insufficient to determine the accurate slope type, so the current slope type can be determined as the default type. The default type can be preset by the user. For example, it can be a rugged type.

[0207] S1204, determining an index of the current frame based on the frame number of the current frame and the preset window length;

[0208] Since the number of frames of the current frame is greater than the preset window length, the electronic device can determine the index of the current frame based on the number of frames of the current frame and the preset window length, that is, index=mod(frame), where mod is a remainder operation.

[0209] Specifically, the electronic device may determine the remainder obtained by dividing the number of frames of the current frame by the preset window length as the index of the current frame. For example, assuming that the number of frames of the current frame is 54 and the preset window length is 32, the index of the current frame may be determined to be 22.

[0210] S1205, reducing the count corresponding to the slope type to which the slope recognition result corresponding to the index of the current frame belongs by one;

[0211] Since the statistical range is always the number of slope recognition results of the preset window length, after determining the index corresponding to the current frame, it is necessary to reduce the count corresponding to the slope type to which the slope recognition result corresponding to the index of the current frame belongs by one, that is, to reduce the count corresponding to the slope type to which the slope recognition result originally corresponding to the index belongs by one.

[0212] Specifically, the slope recognition result originally corresponding to the index of the current frame may be determined first, that is, indexNew=typeArray[index], where indexNew represents the index of the updated type storage array.

[0213] Next, the electronic device may reduce the count corresponding to the slope type to which the slope recognition result originally corresponding to the index of the current frame belongs by one, that is, typeNum[indexNew]--.

[0214] S1206, replacing the slope recognition result corresponding to the index of the current frame with the slope recognition result corresponding to the current frame;

[0215] The electronic device can replace the slope recognition result corresponding to the index of the current frame with the slope recognition result corresponding to the current frame, that is, use the slope recognition result corresponding to the current frame to update the slope recognition result originally corresponding to the index of the current frame, that is, typeArray[index]=slopeFlag.

[0216] S1207, adding one to the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs;

[0217] After updating the slope recognition result corresponding to the index of the current frame, the electronic device may add one to the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs, that is, typeNum[slopeFlag]++.

[0218] S1208: Determine that the current slope type is the corresponding slope type with the highest count.

[0219] Since the number of slope recognition results counted is the preset window length, it can better reflect the road conditions, so the current slope type can be determined as the corresponding slope type with the highest count, that is, the slope type with the largest typeNum number is determined as the current slope type.

[0220] For example, assuming that the preset window length is 32 and the number of frames of the current frame is 35, the electronic device can determine that the index corresponding to the current frame is 3. Assuming that the slope recognition result corresponding to the previous frame with an index of 3 is a rugged type, and the counts corresponding to the flat type and the rugged type are 20 and 12 respectively, the count corresponding to the rugged type can be reduced by one, and the count corresponding to the rugged type is changed from 12 to 11.

[0221] If the slope recognition result corresponding to the current frame is a flat type, then the slope recognition result corresponding to index 3 can be updated from a rugged type to a flat type, and then the count corresponding to the flat type is increased by one, and the count corresponding to the flat type is changed from 20 to 21. Since the counts corresponding to the flat type and the rugged type after the update are 21 and 11 respectively, it can be determined that the count corresponding to the flat type is higher, and then the current slope type is determined to be a flat type.

[0222] It can be seen that in the embodiment of the present application, when the number of slope recognition results counted does not reach the preset window length, the current slope type can be first confirmed as the default type to avoid inaccurate statistics caused by insufficient number of slope recognition results. When the number of slope recognition results counted reaches the preset window length, the current slope type can be determined by comprehensively considering the preset number of slope recognition results, which can improve the accuracy of determining the current slope type.

[0223] As an implementation method of the present application, Fig.14As shown, the step of calibrating the pitch angle of the radar according to the relationship between the pitch angle deviation and the preset deviation range may include:

[0224] S1401, determining whether the pitch angle deviation is within a preset deviation range; if the pitch angle deviation is within the preset deviation range, executing step S1402; if the pitch angle deviation is not within the preset deviation range, executing step S1403;

[0225] When the pitch angle deviation is small, it means that the deflection degree of the radar is small, and the pitch angle deviation can be used to compensate the pitch angle of the radar. In order to determine whether the current pitch angle deviation of the radar meets the above conditions, the electronic device can determine whether the pitch angle deviation is within a preset deviation range.

[0226] S1402: Use the pitch angle deviation as the pitch angle for calibration.

[0227] If the pitch angle deviation is within the preset deviation range, the electronic device may use the pitch angle deviation as the pitch angle for calibration and use the pitch angle deviation to compensate for the pitch angle of the radar.

[0228] S1403, prompting the user to adjust the installation angle of the radar.

[0229] If the pitch angle deviation is not within the preset deviation range, it means that the radar is deflected to a large extent, then the electronic device can prompt the user to manually adjust the installation angle of the radar.

[0230] It can be seen that in the embodiment of the present application, the electronic device can determine whether the pitch angle deviation is within the preset deviation range; if the pitch angle deviation is within the preset deviation range, the pitch angle deviation is used as the pitch angle for calibration. In this way, when the pitch angle deviation is small, the pitch angle of the radar can be calibrated by the pitch angle deviation, thereby improving the accuracy of the subsequent use of the radar.

[0231] As an implementation method of the embodiment of the present application, a flowchart of a method for determining a radar calibration result can be as follows: Fig.15 As shown, it may specifically include:

[0232] S1501, obtaining vehicle body data;

[0233] When calibrating the radar pitch angle, the electronic device can obtain the pitch angle detected by the radar, that is, the pitch angle with installation error.

[0234] S1502, whether the road surface is flat; if yes, execute step S1503; if no, end;

[0235] The pitch angle calibration needs to be performed when the driving state of the vehicle meets the preset calibration conditions. The preset calibration conditions may include a preset uniform straight-line driving condition and a preset flat road surface condition. The electronic device may first determine whether the road surface on which the vehicle is driving is flat. If the road surface is flat, the electronic device may continue to execute step S1503. Otherwise, the process will end.

[0236] S1503, whether the uniform speed straight-line driving condition is met; if yes, execute step S1504; if no, end;

[0237] After determining the road surface platform, the electronic device can determine whether the vehicle meets the uniform speed straight driving condition. If the vehicle meets the uniform speed straight driving condition, it means that the current calibration environment meets the above preset calibration conditions, and the electronic device can continue to perform step S1504. Otherwise, the process will end.

[0238] S1504, locating ground clutter area;

[0239] The electronic device can obtain a multi-frame range Doppler map obtained by processing the echo signal collected by the radar when the driving state of the vehicle meets the preset calibration conditions. Then, the ground clutter area is located in each frame of the range Doppler map.

[0240] S1505, selecting candidate ground clutter points that meet preset conditions;

[0241] For each frame of the range Doppler map, the electronic device can select multiple candidate ground clutter points that meet preset conditions from the ground clutter area of ​​the frame of the range Doppler map. The preset condition can be a preset number of ground clutter points with the highest corresponding signal-to-noise ratio in the ground clutter area.

[0242] S1506, whether the number of point clouds reaches a first preset threshold; if yes, execute step S1507; if no, end;

[0243] The electronic device may determine whether the number of point clouds meets a first preset threshold, where the number of point clouds is the number of candidate ground clutter points selected in the above step, and the first preset threshold may be set according to actual needs, for example, may be 300. If the number of point clouds reaches the first preset threshold, it means that sufficient candidate ground clutter points have been collected, and then step S1507 may be continued. Otherwise, the process will end.

[0244] S1507, calculating an average value of the standard pitch angles;

[0245] For each candidate ground clutter point, the electronic device may calculate the standard pitch angle of the radar corresponding to the candidate ground clutter point, obtain a first preset threshold number of standard pitch angles, and then calculate an average value of the standard pitch angles.

[0246] S1508, calculating the variance of the standard pitch angle;

[0247] In order to determine the fluctuation of the data, the electronic device may calculate the variance of the standard pitch angles having a number equal to the first preset threshold.

[0248] S1509, whether the variance is less than a second preset threshold; if yes, execute step S1510; if no, end;

[0249] If the variance is less than the second preset threshold, it means that the fluctuation of the data is small, and then step S1510 can be continued. Otherwise, the process will end. The second preset threshold can be set according to actual needs, for example, it can be 0.001.

[0250] S1510, output calibration results.

[0251] The electronic device may determine the difference between the calculated standard pitch angle and the pitch angle detected by the radar as the pitch angle deviation. Assuming that the pitch angle deviation is within a preset deviation range, the pitch angle of the radar is calibrated based on the pitch angle deviation.

[0252] In this way, the pitch angle deviations of multiple frames and multiple points can be counted. When the set variance and preset deviation range are met, the statistical average value is used as the calibration angle of the radar pitch angle. This method has the advantages of simple method, fast calibration speed and high calibration accuracy, and can meet the needs of mass production automatic calibration.

[0253] In the technical solution of this application, the operations involved in obtaining, storing, using, processing, transmitting, providing and disclosing user personal information are all carried out with the user's authorization.

[0254] Corresponding to the above-mentioned radar pitch angle calibration method, the embodiment of the present application further provides a radar pitch angle calibration device. The following is an introduction to a radar pitch angle calibration device provided in the embodiment of the present application.

[0255] like Fig.16 As shown, a radar pitch angle calibration device, the radar is installed on a vehicle, the radar is used to transmit radar signals to the outside world and receive echo signals reflected by the outside world, the device includes:

[0256] The range Doppler map acquisition module 1601 is used to acquire a range Doppler map obtained by processing the echo signal collected by the radar, wherein the echo signal is collected by the radar when the driving state of the vehicle meets the preset calibration conditions, and the preset calibration conditions include a preset uniform straight-line driving condition and a preset flat road surface condition, and the range Doppler map is a two-dimensional relationship diagram between distance and speed;

[0257] A ground clutter region determination module 1602 is used to determine a range dimension range and a speed dimension range in the range Doppler map to obtain a ground clutter region, wherein the ground clutter region is a region corresponding to an echo signal reflected from the ground collected by the radar when the driving state of the vehicle meets the preset calibration condition;

[0258] A standard pitch angle calculation module 1603 is used to select a plurality of candidate ground clutter points from the ground clutter area, and calculate the standard pitch angle of the radar corresponding to each candidate ground clutter point according to the distance value corresponding to each candidate ground clutter point in the range Doppler map and the installation height of the radar;

[0259] The pitch angle deviation calculation module 1604 is used to calculate the pitch angle deviation corresponding to the radar based on the standard pitch angle corresponding to each candidate ground clutter point and the pitch angle detected by the radar;

[0260] The pitch angle calibration module 1605 is used to calibrate the pitch angle of the radar according to the relationship between the pitch angle deviation and a preset deviation range.

[0261] It can be seen that in the embodiment of the present application, the electronic device can obtain a range Doppler map obtained by processing the echo signal collected by the radar, wherein the echo signal is collected by the radar when the driving state of the vehicle meets the preset calibration conditions, the preset calibration conditions include preset uniform straight driving conditions and preset road flatness conditions, and the range Doppler map is a two-dimensional relationship diagram between distance and speed; determine the distance dimension range and the speed dimension range in the range Doppler map to obtain a ground clutter area, wherein the ground clutter area is the area corresponding to the echo signal reflected by the ground collected by the radar when the driving state of the vehicle meets the preset calibration conditions; select multiple candidate ground clutter points from the ground clutter area, and calculate the standard pitch angle of the radar corresponding to each candidate ground clutter point according to the distance value corresponding to each candidate ground clutter point in the range Doppler map and the installation height of the radar; calculate the pitch angle deviation corresponding to the radar based on the standard pitch angle corresponding to each candidate ground clutter point and the pitch angle detected by the radar; calibrate the pitch angle of the radar according to the relationship between the pitch angle deviation and the preset deviation range. After sending out a signal, the radar will receive an echo signal from the ground, i.e., ground clutter. In the range Doppler map obtained by processing the radar echo signal, there is a ground clutter area, and the ground clutter points in the ground clutter area correspond to ground points in the physical world. Through the distance value corresponding to the ground clutter point in the range Doppler map and the range resolution of the radar, the distance between the ground point corresponding to the ground clutter point and the radar can be calculated. Combined with the installation height of the radar, the standard pitch angle corresponding to the radar can be calculated. Since the range Doppler map is obtained by processing the echo signal collected by the radar when the vehicle meets the conditions of uniform straight driving and flat road conditions, the standard pitch angle is the pitch angle when there is no installation error of the radar, and the pitch angle detected by the radar is the pitch angle when there is an installation error of the radar. Therefore, the difference between the standard pitch angle and the pitch angle detected by the radar can be used to determine the pitch angle deviation corresponding to the radar, and then calibrate the pitch angle of the radar. In this way, the safety hazards caused by the installation error of the vehicle-mounted radar in the pitch direction can be avoided. Moreover, the calibration speed is relatively fast, and the user can automatically calibrate in real time while driving, without having to complete the calibration before driving, so the calibration process is relatively simple.

[0262] As an implementation of the embodiment of the present application, the ground clutter region determination module 1602 may include:

[0263] A first boundary determination submodule, configured to determine an upper boundary and a lower boundary of a ground clutter region corresponding to a velocity dimension in the range Doppler map according to a vehicle speed of the vehicle, a preset number of extended index units, and a velocity resolution of the radar;

[0264] A second boundary determination submodule is used to determine, in the range Doppler map, a left boundary and a right boundary corresponding to the ground clutter area in the range dimension based on a distance value corresponding to the stationary obstacle closest to the radar in the range Doppler map and a lower limit of the radar's elevation detection range;

[0265] The ground clutter region determination submodule is used to determine the region consisting of the upper boundary, the lower boundary, the left boundary and the right boundary as the ground clutter region.

[0266] As an implementation of the embodiment of the present application, the first boundary determination submodule may include:

[0267] A vehicle speed acquisition unit, used to acquire the vehicle speed when the radar collects the echo signal;

[0268] a speed index determination unit, configured to calculate a quotient between the vehicle speed and the speed resolution of the radar, and round the quotient to obtain a speed index;

[0269] An extension value calculation unit, used to calculate a multiplication value between a preset number of extension index units and a velocity resolution of the radar to obtain an extension value;

[0270] The first boundary determination unit is used to use the product of the velocity index and the velocity resolution as the midpoint, and the difference between the value of the midpoint and the two values ​​of the extended value as the left boundary and the right boundary of the ground clutter area corresponding to the velocity dimension.

[0271] As an implementation of the embodiment of the present application, the second boundary determination submodule may include:

[0272] A second boundary determination unit is used to determine a distance value corresponding to a stationary obstacle closest to the radar in the range Doppler map as a right boundary of the ground clutter area corresponding to the range dimension;

[0273] The third boundary determination unit is used to determine the left boundary of the ground clutter area corresponding to the distance dimension based on the lower limit of the radar pitch dimension detection range.

[0274] As an implementation of the embodiment of the present application, the standard pitch angle calculation module 1603 may include:

[0275] The candidate ground clutter point selection submodule is used to select a preset number of ground clutter points with the highest corresponding signal-to-noise ratio from the ground clutter area as candidate ground clutter points.

[0276] As an implementation of the embodiment of the present application, the pitch angle deviation calculation module 1604 may include:

[0277] A ground clutter point screening submodule, configured to screen the candidate ground clutter points based on the signal-to-noise ratio, azimuth, and standard pitch angle corresponding to the candidate ground clutter points to obtain target ground clutter points, wherein the azimuth is the angle between the line connecting the ground point corresponding to the ground clutter point in the physical world and the radar and the normal to the radar;

[0278] A standard deviation calculation submodule, configured to calculate the standard deviation of the standard pitch angles corresponding to the preset number of target ground clutter points when the number of the target ground clutter points reaches a preset number;

[0279] The pitch angle deviation determination submodule is used to calculate the average value of the standard pitch angles corresponding to the preset number of target ground clutter points if the standard deviation is less than a preset threshold, and use the difference between the average value and the pitch angle detected by the radar as the pitch angle deviation corresponding to the radar.

[0280] As an implementation of the embodiment of the present application, the standard pitch angle calculation module 1603 may include:

[0281] A distance calculation submodule, used to calculate the multiplication value between the distance index corresponding to each candidate ground clutter point in the range Doppler map and the distance resolution of the radar, and obtain the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar;

[0282] The standard pitch angle calculation submodule is used to calculate the standard pitch angle of the radar corresponding to each candidate ground clutter point according to the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar and the installation height of the radar according to the inverse sine function.

[0283] As an implementation of the embodiment of the present application, the above device may further include:

[0284] A vehicle parameter acquisition module, used for acquiring the acceleration and turning radius of the vehicle before the step of acquiring the range Doppler map obtained by processing the echo signal collected by the radar;

[0285] The condition determination module is used to determine that the driving state of the vehicle meets the uniform speed straight driving condition if the acceleration is within a preset acceleration range and the turning radius is greater than a preset radius.

[0286] As an implementation of the embodiment of the present application, the above device may further include:

[0287] The recognition result acquisition module is used to obtain the slope recognition results corresponding to multiple frames before the step of obtaining the range Doppler map obtained by processing the echo signal collected by the radar, and each time the slope recognition result corresponding to a frame is obtained, determine whether the frame number of the current frame obtained is greater than the preset window length;

[0288] A counting and statistics module is used to determine, if the number of frames of the current frame is not greater than the preset window length, the index of the current frame as the number of frames of the current frame, and determine the slope recognition result corresponding to the index of the current frame as the slope recognition result corresponding to the current frame; and increase the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs by one;

[0289] A slope type determination module is used to determine the index of the current frame based on the frame number of the current frame and the preset window length if the frame number of the current frame is greater than the preset window length; reduce the count corresponding to the slope type to which the slope recognition result corresponding to the index of the current frame belongs by one; replace the slope recognition result corresponding to the index of the current frame with the slope recognition result corresponding to the current frame; increase the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs by one; and determine that the current slope type is the slope type with the highest corresponding count.

[0290] As an implementation of the embodiment of the present application, the pitch angle calibration module 1605 may include:

[0291] A deviation range determination submodule, used to determine whether the pitch angle deviation is within a preset deviation range;

[0292] The pitch angle determination submodule is configured to use the pitch angle deviation as the pitch angle for calibration if the pitch angle deviation is within the preset deviation range.

[0293] The present application also provides an electronic device, such as Fig.17 As shown, including:

[0294] Memory 1701, used for storing computer programs;

[0295] The processor 1702 is used to implement the radar elevation angle calibration method described in any of the above embodiments when executing the program stored in the memory 1701.

[0296] It can be seen that in the embodiment of the present application, the electronic device can obtain a range Doppler map obtained by processing the echo signal collected by the radar, wherein the echo signal is collected by the radar when the driving state of the vehicle meets the preset calibration conditions, the preset calibration conditions include preset uniform straight driving conditions and preset road flatness conditions, and the range Doppler map is a two-dimensional relationship diagram between distance and speed; determine the distance dimension range and the speed dimension range in the range Doppler map to obtain a ground clutter area, wherein the ground clutter area is the area corresponding to the echo signal reflected by the ground collected by the radar when the driving state of the vehicle meets the preset calibration conditions; select multiple candidate ground clutter points from the ground clutter area, and calculate the standard pitch angle of the radar corresponding to each candidate ground clutter point according to the distance value corresponding to each candidate ground clutter point in the range Doppler map and the installation height of the radar; calculate the pitch angle deviation corresponding to the radar based on the standard pitch angle corresponding to each candidate ground clutter point and the pitch angle detected by the radar; calibrate the pitch angle of the radar according to the relationship between the pitch angle deviation and the preset deviation range. After sending out a signal, the radar will receive an echo signal from the ground, i.e., ground clutter. In the range Doppler map obtained by processing the radar echo signal, there is a ground clutter area, and the ground clutter points in the ground clutter area correspond to ground points in the physical world. Through the distance value corresponding to the ground clutter point in the range Doppler map and the range resolution of the radar, the distance between the ground point corresponding to the ground clutter point and the radar can be calculated. Combined with the installation height of the radar, the standard pitch angle corresponding to the radar can be calculated. Since the range Doppler map is obtained by processing the echo signal collected by the radar when the vehicle meets the conditions of uniform straight driving and flat road conditions, the standard pitch angle is the pitch angle when there is no installation error of the radar, and the pitch angle detected by the radar is the pitch angle when there is an installation error of the radar. Therefore, the difference between the standard pitch angle and the pitch angle detected by the radar can be used to determine the pitch angle deviation corresponding to the radar, and then calibrate the pitch angle of the radar. In this way, the safety hazards caused by the installation error of the vehicle-mounted radar in the pitch direction can be avoided. Moreover, the calibration speed is relatively fast, and the user can automatically calibrate in real time while driving, without having to complete the calibration before driving, so the calibration process is relatively simple.

[0297] In addition, the electronic device may further include a communication bus and / or a communication interface, and the processor 1702, the communication interface, and the memory 1701 communicate with each other via the communication bus.

[0298] The communication bus mentioned in the above electronic device can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, only one thick line is used in the figure, but it does not mean that there is only one bus or one type of bus.

[0299] The communication interface is used for communication between the above electronic device and other devices.

[0300] The memory may include a random access memory (RAM) or a non-volatile memory (NVM), such as at least one disk memory. Optionally, the memory may also be at least one storage device located away from the aforementioned processor.

[0301] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0302] In another embodiment provided in the present application, a computer-readable storage medium is provided, in which a computer program is stored. When the computer program is executed by a processor, the steps of any of the above-mentioned radar elevation angle calibration methods are implemented.

[0303] In another embodiment provided in the present application, a computer program product including instructions is also provided. When the computer program product is executed on a computer, the computer executes any radar elevation angle calibration method in the above embodiments.

[0304] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a solid-state hard disk (SSD), etc.

[0305] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0306] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device, electronic device, computer-readable storage medium, and computer program product embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiments.

[0307] The above description is only a preferred embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.

Claims

1. A radar pitch angle calibration method, characterized in that: The radar is installed on the vehicle, and is used to transmit radar signals to the outside world and receive echo signals reflected by the outside world. The method includes: Acquire a range Doppler map obtained by processing the echo signal collected by the radar, wherein the echo signal is collected by the radar when the driving state of the vehicle meets a preset calibration condition, the preset calibration condition includes a preset uniform straight-line driving condition and a preset flat road surface condition, and the range Doppler map is a two-dimensional relationship diagram between distance and speed; Determining a range dimension range and a speed dimension range in the range Doppler map to obtain a ground clutter region, wherein the ground clutter region is a region corresponding to an echo signal reflected from the ground collected by the radar when the driving state of the vehicle meets the preset calibration condition; Selecting a plurality of candidate ground clutter points from the ground clutter area, and calculating a standard pitch angle of the radar corresponding to each candidate ground clutter point according to a distance value corresponding to each candidate ground clutter point in the range Doppler map and an installation height of the radar; Calculating the pitch angle deviation corresponding to the radar based on the standard pitch angle corresponding to each candidate clutter point and the pitch angle detected by the radar; The pitch angle of the radar is calibrated according to the relationship between the pitch angle deviation and the preset deviation range.

2. The method according to claim 1, characterized in that The step of determining the range dimension range and the velocity dimension range in the range Doppler map to obtain the ground clutter area comprises: Determining, in the range Doppler map, an upper boundary and a lower boundary of a ground clutter region corresponding to a speed dimension according to the speed of the vehicle, a preset number of extended index units, and a speed resolution of the radar; Based on the distance value corresponding to the nearest stationary obstacle to the radar in the range Doppler map and the lower limit of the radar's elevation detection range, determine the left boundary and the right boundary of the ground clutter area in the range Doppler map corresponding to the range dimension; An area consisting of the upper boundary, the lower boundary, the left boundary and the right boundary is determined as the ground clutter area.

3. The method according to claim 2, characterized in that The step of determining the upper boundary and the lower boundary of the ground clutter area corresponding to the speed dimension in the range Doppler map according to the speed of the vehicle, the preset number of extended index units and the speed resolution of the radar comprises: Acquiring the speed of the vehicle when the radar collects the echo signal; Calculating a quotient between the vehicle speed and the speed resolution of the radar, and rounding the quotient to obtain a speed index; Calculating a multiplication value between a preset number of extended index units and a velocity resolution of the radar to obtain an extended value; The product of the velocity index and the velocity resolution is taken as the midpoint, and the difference between the value of the midpoint and the two values ​​of the extension value are respectively used as the left boundary and the right boundary of the ground clutter area corresponding to the velocity dimension.

4. The method according to claim 2, characterized in that: The step of determining the left boundary and the right boundary of the ground clutter area in the range dimension in the range Doppler map based on the distance value corresponding to the stationary obstacle closest to the radar in the range Doppler map and the lower limit of the radar elevation detection range, comprises: Determine a distance value corresponding to the stationary obstacle closest to the radar in the range Doppler map as the right boundary of the ground clutter area corresponding to the range dimension; Based on the lower limit of the radar's elevation-dimension detection range, a left boundary of the ground clutter region corresponding to the distance dimension is determined.

5. The method according to claim 1, characterized in that The step of selecting a plurality of candidate ground clutter points from the ground clutter area comprises: A preset number of ground clutter points with the highest corresponding signal-to-noise ratios are selected from the ground clutter area as candidate ground clutter points.

6. The method according to claim 1, characterized in that The step of calculating the pitch angle deviation corresponding to the radar based on the standard pitch angle corresponding to each candidate clutter point and the pitch angle detected by the radar comprises: Based on the signal-to-noise ratio, azimuth and standard pitch angle corresponding to the candidate ground clutter points, the candidate ground clutter points are screened to obtain target ground clutter points, wherein the azimuth is the angle between the line connecting the ground point corresponding to the ground clutter point in the physical world and the radar and the normal line of the radar; When the number of the target ground clutter points reaches a preset number, calculating the standard deviation of the standard pitch angles corresponding to the preset number of target ground clutter points; If the standard deviation is less than a preset threshold, the average value of the standard pitch angles corresponding to the preset number of target ground clutter points is calculated, and the difference between the average value and the pitch angle detected by the radar is used as the pitch angle deviation corresponding to the radar.

7. The method according to claim 1, characterized in that The step of calculating the standard pitch angle of the radar corresponding to each candidate ground clutter point according to the distance value corresponding to each candidate ground clutter point in the range Doppler map and the installation height of the radar comprises: Calculate the multiplication value between the distance index corresponding to each candidate ground clutter point in the range Doppler map and the distance resolution of the radar to obtain the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar; According to the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar and the installation height of the radar, the standard pitch angle of the radar corresponding to each candidate ground clutter point is calculated according to the inverse sine function.

8. The method according to any one of claims 1 to 7, characterized in that: Before the step of obtaining a range Doppler map obtained by processing the echo signal collected by the radar, the method further includes: Obtaining the acceleration and turning radius of the vehicle; If the acceleration is within a preset acceleration range and the turning radius is greater than a preset radius, it is determined that the driving state of the vehicle satisfies a uniform speed straight-line driving condition.

9. The method according to any one of claims 1 to 7, characterized in that: Before the step of obtaining a range Doppler map obtained by processing the echo signal collected by the radar, the method further includes: Obtain slope recognition results corresponding to multiple frames, and determine whether the number of frames of the current frame obtained is greater than a preset window length each time a slope recognition result corresponding to a frame is obtained; If the frame number of the current frame is not greater than the preset window length, determine the index of the current frame as the frame number of the current frame, and determine the slope recognition result corresponding to the index of the current frame as the slope recognition result corresponding to the current frame; and increase the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs by one; If the frame number of the current frame is greater than the preset window length, determine the index of the current frame based on the frame number of the current frame and the preset window length; reduce the count corresponding to the slope type to which the slope recognition result corresponding to the index of the current frame belongs by one; replace the slope recognition result corresponding to the index of the current frame with the slope recognition result corresponding to the current frame; increase the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs by one; and determine that the current slope type is the slope type with the highest corresponding count.

10. A radar pitch angle calibration device, characterized in that: The radar is installed on the vehicle, and is used to transmit radar signals to the outside world and receive echo signals reflected by the outside world. The device includes: a range Doppler map acquisition module, used to acquire a range Doppler map obtained by processing the echo signal collected by the radar, wherein the echo signal is collected by the radar when the driving state of the vehicle meets a preset calibration condition, the preset calibration condition includes a preset uniform straight-line driving condition and a preset flat road surface condition, and the range Doppler map is a two-dimensional relationship diagram between distance and speed; a ground clutter region determination module, configured to determine a range dimension range and a speed dimension range in the range Doppler map to obtain a ground clutter region, wherein the ground clutter region is a region corresponding to an echo signal reflected from the ground collected by the radar when the driving state of the vehicle satisfies the preset calibration condition; a standard pitch angle calculation module, configured to select a plurality of candidate ground clutter points from the ground clutter area, and calculate a standard pitch angle of the radar corresponding to each candidate ground clutter point according to a distance value corresponding to each candidate ground clutter point in the range Doppler map and an installation height of the radar; A pitch angle deviation calculation module, used to calculate the pitch angle deviation corresponding to the radar based on the standard pitch angle corresponding to each candidate clutter point and the pitch angle detected by the radar; The pitch angle calibration module is used to calibrate the pitch angle of the radar according to the relationship between the pitch angle deviation and a preset deviation range.

11. The device according to claim 10, characterized in that The ground clutter region determination module comprises: A first boundary determination submodule, configured to determine an upper boundary and a lower boundary of a ground clutter region corresponding to a velocity dimension in the range Doppler map according to a vehicle speed of the vehicle, a preset number of extended index units, and a velocity resolution of the radar; A second boundary determination submodule is used to determine, in the range Doppler map, a left boundary and a right boundary corresponding to the ground clutter area in the range dimension based on a distance value corresponding to the stationary obstacle closest to the radar in the range Doppler map and a lower limit of the radar's elevation detection range; a ground clutter region determination submodule, configured to determine a region consisting of the upper boundary, the lower boundary, the left boundary, and the right boundary as the ground clutter region; and / or, The first boundary determination submodule includes: A vehicle speed acquisition unit, used to acquire the vehicle speed when the radar collects the echo signal; a speed index determination unit, configured to calculate a quotient between the vehicle speed and the speed resolution of the radar, and round the quotient to obtain a speed index; An extension value calculation unit, used to calculate a multiplication value between a preset number of extension index units and a velocity resolution of the radar to obtain an extension value; A first boundary determination unit is configured to use the product of the velocity index and the velocity resolution as the midpoint, and the difference between the midpoint and the two values ​​of the extended value as the left boundary and the right boundary of the ground clutter region corresponding to the velocity dimension; and / or, The second boundary determination submodule includes: A second boundary determination unit is used to determine a distance value corresponding to a stationary obstacle closest to the radar in the range Doppler map as a right boundary of the ground clutter area corresponding to the range dimension; A third boundary determination unit is configured to determine a left boundary of the ground clutter area corresponding to the distance dimension based on a lower limit of the radar elevation detection range; and / or, The standard pitch angle calculation module comprises: a candidate ground clutter point selection submodule, configured to select a preset number of ground clutter points with the highest corresponding signal-to-noise ratio from the ground clutter area as candidate ground clutter points; and / or, The pitch angle deviation calculation module includes: A ground clutter point screening submodule, configured to screen the candidate ground clutter points based on the signal-to-noise ratio, azimuth, and standard pitch angle corresponding to the candidate ground clutter points to obtain target ground clutter points, wherein the azimuth is the angle between the line connecting the ground point corresponding to the ground clutter point in the physical world and the radar and the normal to the radar; A standard deviation calculation submodule, configured to calculate the standard deviation of the standard pitch angles corresponding to the preset number of target ground clutter points when the number of the target ground clutter points reaches a preset number; a pitch angle deviation determination submodule, configured to calculate an average value of standard pitch angles corresponding to the preset number of target ground clutter points if the standard deviation is less than a preset threshold, and use the difference between the average value and the pitch angle detected by the radar as the pitch angle deviation corresponding to the radar; and / or, The standard pitch angle calculation module comprises: A distance calculation submodule, used to calculate the multiplication value between the distance index corresponding to each candidate ground clutter point in the range Doppler map and the distance resolution of the radar, and obtain the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar; a standard pitch angle calculation submodule, configured to calculate the standard pitch angle of the radar corresponding to each candidate ground clutter point according to the distance between the ground point corresponding to each candidate ground clutter point in the physical world and the radar and the installation height of the radar, according to the inverse sine function; and / or, The device also includes: A vehicle parameter acquisition module, used for acquiring the acceleration and turning radius of the vehicle before the step of acquiring the range Doppler map obtained by processing the echo signal collected by the radar; a condition determination module, configured to determine that the driving state of the vehicle satisfies a uniform straight-line driving condition if the acceleration is within a preset acceleration range and the turning radius is greater than a preset radius; and / or, The device also includes: The recognition result acquisition module is used to obtain the slope recognition results corresponding to multiple frames before the step of obtaining the range Doppler map obtained by processing the echo signal collected by the radar, and each time the slope recognition result corresponding to a frame is obtained, determine whether the frame number of the current frame obtained is greater than the preset window length; A counting and statistics module is used to determine, if the number of frames of the current frame is not greater than the preset window length, the index of the current frame as the number of frames of the current frame, and determine the slope recognition result corresponding to the index of the current frame as the slope recognition result corresponding to the current frame; and increase the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs by one; A slope type determination module is used to determine the index of the current frame based on the frame number of the current frame and the preset window length if the frame number of the current frame is greater than the preset window length; reduce the count corresponding to the slope type to which the slope recognition result corresponding to the index of the current frame belongs by one; replace the slope recognition result corresponding to the index of the current frame with the slope recognition result corresponding to the current frame; increase the count corresponding to the slope type to which the slope recognition result corresponding to the current frame belongs by one; and determine that the current slope type is the slope type with the highest corresponding count.

12. An electronic device, characterized in that: include: Memory, used to store computer programs; A processor, for implementing any of the methods described in claims 1-9 when executing a program stored in a memory.

13. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 9 is implemented.

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