CN114791591A - Radar calibration method - Google Patents
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- CN114791591A CN114791591A CN202210229559.6A CN202210229559A CN114791591A CN 114791591 A CN114791591 A CN 114791591A CN 202210229559 A CN202210229559 A CN 202210229559A CN 114791591 A CN114791591 A CN 114791591A
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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Abstract
The application discloses a radar calibration method, which comprises the following steps: acquiring absolute stationary point clouds from current frame radar point clouds according to first speed information of each point cloud in the current frame radar point clouds under an automobile body coordinate system and second speed information of reference stationary point clouds under the automobile body coordinate system; calculating a loss function established by the radial speed, the azimuth angle and the pitch angle of the absolute stationary point cloud under a radar coordinate system, and referring to third speed information of the absolute stationary point cloud under the radar coordinate system when the loss function is the minimum value; and determining the pitching installation declination and the horizontal installation declination of the radar according to the first relative rotation matrix rotating from the second speed information to the third speed information and the second relative rotation matrix rotating from the radar coordinate system to the vehicle body coordinate system. The method can automatically determine the pitching installation declination and the horizontal installation declination of the radar without manually building a calibration station to realize radar calibration, thereby saving manpower and material resources and improving the calibration efficiency.
Description
Technical Field
The application relates to the technical field of automobiles, in particular to a radar calibration method.
Background
In recent years, intelligent driving technology is rapidly developed and is attracted by more and more people. Environmental awareness, path planning and decision control are three major modules of intelligent driving technology. The environment perception module is the basis of other two modules, and a better path plan can be obtained and a correct decision can be made only if the environment perception module has good environment perception. At present, the environment perception mainly comprises three sensors, namely a camera, a laser radar and a millimeter wave radar, and the millimeter wave radar has the characteristics of all weather and less environmental influence, so that the sensor becomes an indispensable sensor for intelligent driving gradually. Moreover, a 4D millimeter wave imaging radar having a high azimuth angle and a high pitch angle resolution has been proposed so far, which is capable of generating higher-quality point cloud data.
When a vehicle mounted with a millimeter wave radar travels for a certain period of time, a situation in which the millimeter wave radar is skewed may occur. Under the condition, a driver needs to find out and build a calibration work station after sale, and the millimeter wave radar is calibrated based on the calibration work station. However, the construction and use of the calibration work station consumes a large amount of manpower and material resources, and is suitable for batch calibration, and for a small amount of calibration tasks, the problem of wasting manpower and material resources is caused.
Disclosure of Invention
The application provides a radar calibration method, which can solve the problem that manpower and material resources are wasted due to the fact that a calibration work station needs to be manually built to realize radar calibration in the related technology.
The specific technical scheme is as follows:
in a first aspect, an embodiment of the present application provides a radar calibration method, where the method includes:
acquiring absolute stationary point clouds from current frame radar point clouds according to first speed information of each point cloud in the current frame radar point clouds under an automobile body coordinate system and second speed information of reference stationary point clouds under the automobile body coordinate system;
calculating third speed information of the reference static point cloud under the radar coordinate system when a loss function takes the minimum value, wherein the loss function is established according to the radial speed, the azimuth angle and the pitch angle of the absolute static point cloud under the radar coordinate system;
and determining the pitching installation declination and the horizontal installation declination of the radar according to a first relative rotation matrix rotating from the second speed information to the third speed information and a second relative rotation matrix rotating from the radar coordinate system to the vehicle body coordinate system.
In one embodiment, the first speed information comprises the speed magnitude of each point cloud in the current frame radar point cloud on the y-axis of the vehicle body coordinate system, and the second speed information comprises the speed magnitude of the reference stationary point cloud on the y-axis of the vehicle body coordinate system;
acquiring absolute stationary point clouds from current frame radar point clouds according to first speed information of each point cloud in the current frame radar point clouds under an automobile body coordinate system and second speed information of reference stationary point clouds under the automobile body coordinate system, wherein the method comprises the following steps:
respectively calculating the ratio of the speed of each point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system to the speed of the reference static point cloud on the y axis of the vehicle body coordinate system;
and determining the point cloud with the ratio smaller than a preset ratio threshold value in the current frame radar point cloud as an absolute static point cloud, and acquiring the absolute static point cloud from the current frame radar point cloud.
In one embodiment, the second velocity information further includes velocity magnitudes of the reference stationary point cloud on x-axis and z-axis of the vehicle body coordinate system;
before respectively calculating the ratio of the speed of each point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system to the speed of the reference stationary point cloud on the y axis of the vehicle body coordinate system, the method further comprises:
calculating the speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system according to the vehicle speed, the angular speed of the vehicle under the vehicle body coordinate system and the deviation of the radar coordinate system relative to the vehicle body coordinate system respectively corresponding to the radar point cloud of the current frame;
respectively negating the speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system to obtain the speed of the reference stationary point cloud on the x axis, the y axis and the z axis of the radar coordinate system;
and aiming at the point cloud to be calculated in the current frame radar point cloud, calculating the speed of the point cloud to be calculated on the y axis of the vehicle body coordinate system according to the azimuth angle of the point cloud to be calculated under the radar coordinate system, the pitch angle of the point cloud to be calculated under the radar coordinate system, the radial speed of the point cloud to be calculated under the radar coordinate system and the speed of the reference static point cloud on the x axis and the z axis of the vehicle body coordinate system.
In one embodiment, calculating the speed of the radar on the x-axis, the y-axis and the z-axis of the vehicle body coordinate system according to the vehicle speed, the angular speed of the vehicle under the vehicle body coordinate system and the deviation of the radar coordinate system relative to the vehicle body coordinate system respectively corresponding to the radar point cloud of the current frame comprises:
calculating the speed of the radar on the x axis, the y axis and the z axis of the body coordinate system according to the following formula:
wherein the content of the first and second substances,
and
respectively represents the speed magnitude, omega, of the radar on the x axis, the y axis and the z axis of the body coordinate system x 、ω y And omega z The radar coordinate system respectively represents the angular velocity of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system, and RadarX, RadarY and RadarZ respectively represent the angular velocity of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system,The deviation on the y-axis and z-axis, velocity, represents the speed of the vehicle at the time the current frame radar point cloud was generated.
In one embodiment, for a point cloud to be calculated in the current frame radar point cloud, calculating the speed of the point cloud to be calculated on the y axis of the vehicle body coordinate system according to the azimuth angle of the point cloud to be calculated on the radar coordinate system, the pitch angle of the point cloud to be calculated on the radar coordinate system, the radial speed of the point cloud to be calculated on the radar coordinate system, and the speed of the reference stationary point cloud on the x axis and the z axis of the vehicle body coordinate system, the method includes:
calculating the speed of the ith point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system according to the following formula
Wherein the content of the first and second substances,
the radial velocity magnitude of the ith point cloud under the radar coordinate system is represented,
respectively representing the speed of the reference stationary point cloud on the x axis and the z axis of the vehicle body coordinate system, theta i An azimuth angle of the ith point cloud in the radar coordinate system,
And representing the pitch angle of the ith point cloud under the radar coordinate system.
In one embodiment, the third speed information includes the speed of the reference stationary point cloud on the x-axis, y-axis and z-axis of the radar coordinate system, and the loss function is established based on a least square method, and the loss function is:
wherein, theta 1 、θ 2 …θ N Respectively representing azimuth angles of different point clouds in the current frame radar point cloud under the radar coordinate system,
respectively representing the pitch angles of different point clouds in the current frame radar point cloud under the radar coordinate system,
and
respectively representing the velocity of the point cloud on the x-axis, y-axis and z-axis of the radar coordinate system, and when the loss function takes the minimum value,
and
respectively representing the velocity magnitudes of the reference stationary point cloud on the x-axis, y-axis and z-axis of the radar coordinate system,
respectively representing the radial speed of each absolute stationary point cloud under the radar coordinate system, wherein N is the number of the absolute stationary point clouds in the current frame radar point cloud;
calculating the radial speed of the j absolute stationary point cloud under the radar coordinate system according to the following formula
Wherein, theta j Representing the azimuth angle of the j-th absolute static point cloud in the current frame radar point cloud under the radar coordinate system,
and representing the pitch angle of the jth absolute static point cloud in the current frame radar point cloud under the radar coordinate system.
In one embodiment, the second velocity information includes velocity magnitudes of the reference stationary point cloud on an x-axis, a y-axis, and a z-axis of the body coordinate system, and the third velocity information includes velocity magnitudes of the reference stationary point cloud on the x-axis, the y-axis, and the z-axis of the radar coordinate system;
the calculation method of the first relative rotation matrix comprises the following steps:
calculating an included angle between a first speed vector and a second speed vector, wherein the first speed vector is generated according to the speed of the reference static point cloud in the second speed information on the x axis, the y axis and the z axis of the vehicle body coordinate system, and the second speed vector is generated according to the speed of the reference static point cloud in the third speed information on the x axis, the y axis and the z axis of the radar coordinate system;
calculating an antisymmetric matrix of unit axes of rotation of the first velocity vector and the second velocity vector;
calculating the first relative rotation matrix according to a Rodrigues rotation formula, the included angle and the antisymmetric matrix.
In one embodiment of the method of the present invention,
the second relative rotation matrix
Wherein, theta x Is the angle of rotation, theta, about the x-axis of rotation of the radar coordinate system to the body coordinate system z Is the angle of rotation about the z-axis of the radar coordinate system when rotated towards the body coordinate system.
In one embodiment, acquiring an absolute stationary point cloud from a current frame radar point cloud according to first speed information of each point cloud in the current frame radar point cloud under a vehicle body coordinate system and second speed information of a reference stationary point cloud under the vehicle body coordinate system comprises: under the condition that the vehicle speed corresponding to the current frame radar point cloud is greater than a preset vehicle speed threshold value, acquiring absolute stationary point cloud from the current frame radar point cloud according to first speed information of each point cloud in the current frame radar point cloud under a vehicle body coordinate system and second speed information of reference stationary point cloud under the vehicle body coordinate system;
and/or calculating third speed information of the reference stationary point cloud under the radar coordinate system when the loss function takes the minimum value, wherein the third speed information comprises the following steps: and under the condition that the number of the absolute static point clouds in the current frame radar point cloud is larger than a preset number threshold, calculating third speed information of the reference static point cloud under the radar coordinate system when the loss function takes the minimum value.
In one embodiment, the method further comprises:
generating a first vector based on M pitching installation declination angles corresponding to continuous M frames of radar point clouds, and generating a second vector based on M horizontal installation declination angles corresponding to the continuous M frames of radar point clouds, wherein M is a positive integer;
performing histogram statistics on the first vector and the second vector to obtain at least one mode of the pitch installation declination and at least one mode of the horizontal installation declination;
determining an average of at least one mode of the pitch stagger angle as a final desired pitch stagger angle, and determining an average of at least one mode of the horizontal stagger angle as a final desired horizontal stagger angle.
In a second aspect, another embodiment of the present application provides a radar calibration apparatus, where the apparatus includes:
the acquisition unit is used for acquiring absolute stationary point clouds from the current frame radar point clouds according to first speed information of each point cloud in the current frame radar point clouds under an automobile body coordinate system and second speed information of reference stationary point clouds under the automobile body coordinate system;
the calculation unit is used for calculating third speed information of the reference static point cloud under the radar coordinate system when a loss function takes the minimum value, wherein the loss function is established according to the radial speed, the azimuth angle and the pitch angle of the absolute static point cloud under the radar coordinate system;
and the determining unit is used for determining a pitching installation declination and a horizontal installation declination of the radar according to a first relative rotation matrix of the second speed information rotating to the third speed information and a second relative rotation matrix of the radar coordinate system rotating to the vehicle body coordinate system.
In one embodiment, the first speed information comprises the speed magnitude of each point cloud in the current frame radar point cloud on the y-axis of the vehicle body coordinate system, and the second speed information comprises the speed magnitude of the reference stationary point cloud on the y-axis of the vehicle body coordinate system;
an acquisition unit including:
the calculation module is used for respectively calculating the ratio of the speed of each point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system to the speed of the reference static point cloud on the y axis of the vehicle body coordinate system;
and the determining and acquiring module is used for determining the point cloud with the ratio smaller than a preset ratio threshold in the current frame radar point cloud as an absolute static point cloud and acquiring the absolute static point cloud from the current frame radar point cloud.
In one embodiment, the second velocity information further includes velocity magnitudes of the reference stationary point cloud on x-axis and z-axis of the body coordinate system;
the calculation module is further used for calculating the speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system according to the vehicle speed, the angular speed of the vehicle under the vehicle body coordinate system and the deviation of the radar coordinate system relative to the vehicle body coordinate system corresponding to the current frame radar point cloud respectively before the ratio of the speed of each point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system to the speed of the reference stationary point cloud on the y axis of the vehicle body coordinate system is calculated respectively;
the acquisition unit further includes:
the negation module is used for respectively negating the speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system to obtain the speed of the reference stationary point cloud on the x axis, the y axis and the z axis of the radar coordinate system;
and the calculation module is also used for calculating the speed of the point cloud to be calculated on the y axis of the vehicle body coordinate system according to the azimuth angle of the point cloud to be calculated under the radar coordinate system, the pitch angle of the point cloud to be calculated under the radar coordinate system, the radial speed of the point cloud to be calculated under the radar coordinate system and the speed of the reference static point cloud on the x axis and the z axis of the vehicle body coordinate system.
In one embodiment, a computing module to
Calculating the speed of the radar on the x axis, the y axis and the z axis of the body coordinate system according to the following formula:
wherein, the first and the second end of the pipe are connected with each other,
and
respectively indicating that the radar is seated on the vehicle bodyThe scale is the magnitude of the velocity, ω, on the x, y and z axes x 、ω y And omega z The angular speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system is respectively represented, and RadarX, RadarY and RadarZ respectively represent the deviation of the radar coordinate system on the x axis, the y axis and the z axis relative to the vehicle body coordinate system, and the velocity of the vehicle when the radar point cloud of the current frame is generated is represented.
In one embodiment, a computing module for
Calculating the speed of the ith point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system according to the following formula
Wherein, the first and the second end of the pipe are connected with each other,
the radial speed of the ith point cloud under the radar coordinate system is represented,
respectively representing the speed of the reference stationary point cloud on the x axis and the z axis of the vehicle body coordinate system, theta i Indicating the azimuth angle of the ith point cloud under the radar coordinate system,
And representing the pitch angle of the ith point cloud under the radar coordinate system.
In one embodiment, the third velocity information includes velocity magnitudes of the reference stationary point cloud in x, y, and z axes of the radar coordinate system, and the loss function is established based on a least square method, and the loss function is:
wherein, theta 1 、θ 2 …θ N Respectively representing the azimuth angles of different point clouds in the current frame radar point cloud under the radar coordinate system,
respectively representing the pitch angles of different point clouds in the current frame radar point cloud under the radar coordinate system,
and
respectively representing the velocity of the point cloud on the x-axis, y-axis and z-axis of the radar coordinate system, and when the loss function takes the minimum value,
and
respectively representing the velocity magnitudes of the reference stationary point cloud on the x-axis, y-axis and z-axis of the radar coordinate system,
respectively representing the radial speed of each absolute stationary point cloud under the radar coordinate system, wherein N is the number of the absolute stationary point clouds in the radar point cloud of the current frame;
a calculating unit for calculating the radial velocity of the j absolute stationary point cloud under the radar coordinate system according to the following formula
Wherein，θ j Representing an azimuth angle of a j-th absolute stationary point cloud in the current frame radar point cloud under the radar coordinate system,
and representing the pitch angle of the jth absolute static point cloud in the current frame radar point cloud under the radar coordinate system.
In one embodiment, the second velocity information includes velocity magnitudes of the reference stationary point cloud on an x-axis, a y-axis, and a z-axis of the body coordinate system, and the third velocity information includes velocity magnitudes of the reference stationary point cloud on the x-axis, the y-axis, and the z-axis of the radar coordinate system;
the determining unit is further used for calculating an included angle between a first speed vector and a second speed vector, wherein the first speed vector is generated according to the speed of the reference stationary point cloud in the second speed information on the x axis, the y axis and the z axis of the vehicle body coordinate system, and the second speed vector is generated according to the speed of the reference stationary point cloud in the third speed information on the x axis, the y axis and the z axis of the radar coordinate system; calculating an antisymmetric matrix of unit axes of rotation of the first velocity vector and the second velocity vector; calculating the first relative rotation matrix from the Rodrigues rotation formula, the included angle, and the antisymmetric matrix.
In one embodiment of the method of the present invention,
the second relative rotation matrix
Wherein, theta x Is the angle of rotation, theta, about the x-axis of rotation of the radar coordinate system to the body coordinate system z Is the angle of rotation about the z-axis of the radar coordinate system when rotated towards the body coordinate system.
In one embodiment, the obtaining unit is configured to, when a vehicle speed corresponding to the current frame radar point cloud is greater than a preset vehicle speed threshold, obtain an absolute stationary point cloud from the current frame radar point cloud according to first speed information of each point cloud in the current frame radar point cloud in a vehicle body coordinate system and second speed information of a reference stationary point cloud in the vehicle body coordinate system;
and/or the presence of a gas in the gas,
and the calculating unit is used for calculating third speed information of the reference static point cloud under the radar coordinate system when the loss function takes the minimum value under the condition that the number of the absolute static point clouds in the current frame radar point cloud is greater than a preset number threshold.
In one embodiment, the apparatus further comprises:
the device comprises a generating unit, a calculating unit and a processing unit, wherein the generating unit is used for generating a first vector based on M pitching installation declination angles corresponding to continuous M frames of radar point clouds and generating a second vector based on M horizontal installation declination angles corresponding to the continuous M frames of radar point clouds, and M is a positive integer;
a statistical unit, configured to perform histogram statistics on the first vector and the second vector to obtain at least one mode of the pitch installation declination and at least one mode of the horizontal installation declination;
a determining unit, further configured to determine an average of at least one mode of the pitch stagger angle as a final required pitch stagger angle, and determine an average of at least one mode of the horizontal stagger angle as a final required horizontal stagger angle.
In a third aspect, another embodiment of the present application provides a storage medium having stored thereon executable instructions, which when executed by a processor, cause the processor to implement the method according to any one of the embodiments of the first aspect.
In a fourth aspect, another embodiment of the present application provides an electronic device, including:
one or more processors;
a storage device for storing one or more programs,
wherein the one or more programs, when executed by the one or more processors, cause the one or more processors to implement the method of any embodiment of the first aspect.
As can be seen from the above, according to the radar calibration method provided in the embodiment of the present application, an absolute stationary point cloud can be obtained from a current frame radar point cloud according to first speed information of each point cloud in the current frame radar point cloud in an automobile body coordinate system and second speed information of a reference stationary point cloud in the automobile body coordinate system, when a loss function established by a radial speed, an azimuth angle and a pitch angle of the absolute stationary point cloud in the radar coordinate system is calculated to obtain a minimum value, third speed information of the reference stationary point cloud in the radar coordinate system is calculated, and finally a pitch installation declination and a horizontal installation declination of a radar are determined according to a first relative rotation matrix of the second speed information rotating to the third speed information and a second relative rotation matrix of the radar coordinate system rotating to the automobile body coordinate system, and according to related information of the radar data, inertial guidance information and the like in a vehicle driving process The deflection angle is installed, and a calibration station is not required to be manually built to realize radar calibration, so that manpower and material resources are saved, and the calibration efficiency is improved.
The technical effects that can be achieved by the embodiments of the present application further include, but are not limited to, the following:
1. because different vehicle speeds have different influences on radar calibration, in order to improve the radar calibration accuracy, the pitching installation declination and the horizontal installation declination corresponding to the current frame radar point cloud can be calculated only under the condition that the vehicle speed corresponding to the current frame radar point cloud is greater than the preset vehicle speed threshold.
2. In order to improve the accuracy of the third speed information, after the absolute stationary point clouds are obtained, whether the number of the absolute stationary point clouds is larger than a preset number threshold value or not is judged, and the pitching installation declination and the horizontal installation declination corresponding to the current frame radar point clouds are calculated only when the number of the absolute stationary point clouds is larger than the preset number threshold value.
3. In order to eliminate the random error of the system, the pitching installation declination and the horizontal installation declination of continuous M frames of radar point clouds can be counted to obtain the final required pitching installation declination and horizontal installation declination, so that the accuracy of radar calibration is improved.
Of course, not all advantages described above need to be achieved at the same time in the practice of any one product or method of the present application.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It is to be understood that the drawings in the following description are of some embodiments of the application. For a person skilled in the art, without inventive effort, further figures can be obtained from these figures.
Fig. 1 is a schematic flowchart of a radar calibration method according to an embodiment of the present disclosure;
fig. 2 is a schematic flowchart of another radar calibration method provided in the embodiment of the present application;
FIG. 3 is a schematic diagram of a coordinate system provided by an embodiment of the present application;
fig. 4 is a schematic flowchart of another radar calibration method provided in the embodiment of the present application;
fig. 5 is a block diagram of a radar calibration apparatus according to an embodiment of the present application.
Detailed Description
The technical solution in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It should be apparent that the described embodiments are only a few embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without inventive step, are within the scope of the present disclosure.
It should be noted that the terms "comprises" and "comprising," and any variations thereof, in the examples and figures herein, are intended to cover non-exclusive inclusions. A process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements but may alternatively include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Fig. 1 is a schematic flowchart of a radar calibration method provided in an embodiment of the present application, where the method may be applied to a vehicle end or a server end, and when the method is applied to the server end, a vehicle may transmit relevant data to the server for processing, where the method mainly includes:
s110: and acquiring the absolute stationary point cloud from the current frame radar point cloud according to the first speed information of each point cloud in the current frame radar point cloud under the vehicle body coordinate system and the second speed information of the reference stationary point cloud under the vehicle body coordinate system.
The first speed information comprises the speed of each point cloud in the radar point cloud of the current frame on the y axis of the vehicle body coordinate system, and the second speed information comprises the speed of the reference static point cloud on the y axis of the vehicle body coordinate system.
As shown in fig. 2, a specific implementation manner of this step may include steps S111-S112:
(S111) respectively calculating the ratio of the speed of each point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system to the speed of the reference static point cloud on the y axis of the vehicle body coordinate system.
The second speed information also comprises the speed of the reference static point cloud on the x-axis and the z-axis of the vehicle body coordinate system.
The implementation process of calculating the speed of each point cloud on the y axis of the vehicle body coordinate system and the speed of the reference stationary point cloud on the y axis of the vehicle body coordinate system comprises the steps of A01-A03:
(A01) and calculating the speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system according to the vehicle speed, the angular speed of the vehicle under the vehicle body coordinate system and the deviation of the radar coordinate system relative to the vehicle body coordinate system respectively corresponding to the radar point cloud of the current frame.
Calculating the speed of the radar on the x axis, the y axis and the z axis of the body coordinate system according to the following formula:
wherein the content of the first and second substances,
and
respectively represents the speed magnitude, omega, of the radar on the x axis, the y axis and the z axis of the body coordinate system x 、ω y And omega z The angular speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system is respectively represented, and RadarX, RadarY and RadarZ respectively represent the deviation of the radar coordinate system on the x axis, the y axis and the z axis relative to the vehicle body coordinate system, and Vehiclespeed represents the speed of the vehicle when the current frame radar point cloud is generated. Fig. 3 is a schematic diagram of the radar coordinate system and the body coordinate system, showing x-axis and y-axis information (z-axis not shown) of the radar coordinate system and the body coordinate system, and deviations RadarX and RadarY of the two in the x-axis and y-axis. Further, the vehicle speed, the angular velocity of the vehicle in the body coordinate system, may be measured by an IMU (Inertial Measurement Unit).
(A02) And respectively negating the speeds of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system to obtain the speeds of the reference stationary point cloud on the x axis, the y axis and the z axis of the radar coordinate system.
The relative motion vector of the reference static point cloud under the vehicle body coordinate system is opposite to the motion vector of the radar, so that the speed of the reference static point cloud on the x axis, the y axis and the z axis of the radar coordinate system can be obtained by respectively negating the speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system. Is formulated as follows:
wherein, the first and the second end of the pipe are connected with each other,
and respectively representing the speed of the reference stationary point cloud on an x axis, a y axis and a z axis of the radar coordinate system.
(A03) And aiming at the point cloud to be calculated in the current frame radar point cloud, calculating the speed of the point cloud to be calculated on the y axis of the vehicle body coordinate system according to the azimuth angle of the point cloud to be calculated under the radar coordinate system, the pitch angle of the point cloud to be calculated under the radar coordinate system, the radial speed of the point cloud to be calculated under the radar coordinate system and the speed of the reference static point cloud on the x axis and the z axis of the vehicle body coordinate system.
Because the installation angle is smaller, the
The influence of (2) is small, so that the speed of the ith point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system can be calculated according to the following formula
Wherein the content of the first and second substances,
representing the ith point cloud in the radar coordinate systemThe magnitude of the radial velocity of the lower beam,
respectively representing the speed of the reference stationary point cloud on the x axis and the z axis of the vehicle body coordinate system, theta i An azimuth angle of the ith point cloud in the radar coordinate system,
And representing the pitch angle of the ith point cloud under the radar coordinate system.
Wherein the content of the first and second substances,
and
respectively representing the speed of the reference stationary point cloud on the x-axis, the y-axis and the z-axis of the radar coordinate system, theta i Representing the azimuth angle of the ith point cloud in the current frame radar point cloud under the radar coordinate system,
and representing the pitch angle of the ith point cloud in the current frame radar point cloud under the radar coordinate system.
(S112) determining the point cloud with the ratio smaller than a preset ratio threshold value in the current frame radar point cloud as an absolute static point cloud, and acquiring the absolute static point cloud from the current frame radar point cloud.
The preset ratio threshold is determined according to the radar characteristics and actual experience, as long as the final radar calibration precision meets the requirement, and may be 1000, for example.
Because the angular deviation of the radar coordinate system is smaller than that of the vehicle body coordinate system, the speed of each point cloud on the x axis of the vehicle body coordinate system and the speed of the reference static point cloud on the x axis of the vehicle body coordinate system can be considered to be equal, and the speed of each point cloud on the y axis of the vehicle body coordinate system and the speed of the reference static point cloud on the y axis of the vehicle body coordinate system can also be considered to be equal. Therefore, the speed of each point cloud on the y axis of the vehicle body coordinate system can be compared with the speed of the reference static point cloud on the y axis of the vehicle body coordinate system, and if the difference is very close, the point cloud to be compared is considered to be the absolute static point cloud.
It should be added that, when the absolute stationary point cloud is obtained from the current frame radar point cloud in step S110, all the absolute stationary point clouds may be obtained to participate in the subsequent calculation, or only a part of the absolute stationary point clouds may be obtained to participate in the subsequent calculation, as long as the number of the absolute stationary point clouds participating in the calculation can meet the requirement of the subsequent calibration precision.
In one embodiment, since different vehicle speeds have different influences on radar calibration, in order to improve the radar calibration accuracy, an absolute stationary point cloud may be obtained from the current frame radar point cloud according to first speed information of each point cloud in the current frame radar point cloud in a vehicle body coordinate system and second speed information of a reference stationary point cloud in the vehicle body coordinate system when a vehicle speed corresponding to the current frame radar point cloud is greater than a preset vehicle speed threshold, and the absolute stationary point cloud may be obtained from the current frame radar point cloud according to the first speed information of each point cloud in the current frame radar point cloud in the vehicle body coordinate system and the second speed information of the reference stationary point cloud in the vehicle body coordinate system when the vehicle speed is less than or equal to the preset vehicle speed threshold. The preset vehicle speed threshold is determined according to actual test experience, and may be 5m/s, for example.
S120: and calculating third speed information of the reference static point cloud under the radar coordinate system when the loss function takes the minimum value.
And the loss function is established according to the radial speed, the azimuth angle and the pitch angle of the absolute stationary point cloud under a radar coordinate system. The third speed information comprises the speed of the reference stationary point cloud on the x axis, the y axis and the z axis of the radar coordinate system, the loss function is established based on the least square method, and the loss function is as follows:
wherein, theta 1 、θ 2 …θ N Respectively representing azimuth angles of different point clouds in the current frame radar point cloud under the radar coordinate system,
respectively representing the pitch angles of different point clouds in the current frame radar point cloud under the radar coordinate system,
and
respectively representing the velocity of the point cloud on the x-axis, y-axis and z-axis of the radar coordinate system, and when the loss function takes the minimum value,
and
respectively representing the velocity magnitudes of the reference stationary point cloud on the x-axis, y-axis and z-axis of the radar coordinate system,
and respectively representing the radial speed of each absolute stationary point cloud under the radar coordinate system, wherein N is the number of the absolute stationary point clouds in the radar point cloud of the current frame.
Calculating the radial speed of the j absolute stationary point cloud under the radar coordinate system according to the following formula
In an embodiment, since the more the number of the absolute stationary point clouds is, the higher the accuracy of the third speed information calculated by using the loss function is, in order to improve the accuracy of the third speed information, it may be determined whether the number of the absolute stationary point clouds is greater than a preset number threshold after the absolute stationary point clouds are obtained, and the step S120 is performed only when the number of the absolute stationary point clouds in the current frame radar point cloud is greater than the preset number threshold, otherwise, the step S120 is not performed. The preset number threshold is determined according to the radar calibration precision requirement.
S130: and determining the pitching installation declination and the horizontal installation declination of the radar according to the first relative rotation matrix rotating from the second speed information to the third speed information and the second relative rotation matrix rotating from the radar coordinate system to the vehicle body coordinate system.
The second speed information comprises the speed of the reference static point cloud on the x axis, the y axis and the z of the vehicle body coordinate system, and the third speed information comprises the speed of the reference static point cloud on the x axis, the y axis and the z of the radar coordinate system.
In one embodiment, the method for calculating the first relative rotation matrix includes:
(B1) and calculating an included angle between a first speed vector and a second speed vector, wherein the first speed vector is generated according to the speed of the reference static point cloud in the second speed information on the x axis, the y axis and the z of the vehicle body coordinate system, and the second speed vector is generated according to the speed of the reference static point cloud in the third speed information on the x axis, the y axis and the z of the radar coordinate system.
Assuming a first velocity vector
Second velocity vector
The method for calculating the included angle between the first speed vector and the second speed vector comprises the following steps:
wherein alpha is an included angle.
(B2) An antisymmetric matrix of unit axes of rotation of the first velocity vector and the second velocity vector is calculated.
A unit rotation axis of the first velocity vector and the second velocity vector according to the following formula:
where ω is the unit axis of rotation.
Let ω ═ ω 1 ω 2 ω 3 ] T Of its antisymmetric matrix
Is composed of
(B3) Calculating the first relative rotation matrix according to a Rodrigues rotation formula, the included angle and the antisymmetric matrix.
The rotation matrix can be derived from the rodgers rotation equation as:
wherein, I is a 3 × 3 unit matrix.
In one embodiment, the method for calculating the second relative rotation matrix, which is a rotation matrix common to the radar coordinate system and the vehicle body coordinate system, includes:
the second relative rotation matrix
Wherein, theta x Is the angle of rotation, theta, about the x-axis of rotation of the radar coordinate system to the body coordinate system z Is the angle of rotation about the z-axis when the radar coordinate system is rotated towards the body coordinate system.
After obtaining the first relative rotation matrix and the second relative rotation matrix, the formula may be followed
And calculating to obtain the pitching installation declination and the horizontal installation declination of the radar.
The radar calibration method provided by the embodiment of the application can firstly acquire the absolute stationary point cloud from the current frame radar point cloud according to the first speed information of each point cloud in the current frame radar point cloud under the vehicle body coordinate system and the second speed information of the reference stationary point cloud under the vehicle body coordinate system, then calculate the minimum value of the loss function established by the radial speed, the azimuth angle and the pitch angle of the absolute stationary point cloud under the radar coordinate system, refer to the third speed information of the stationary point cloud under the radar coordinate system, finally determine the pitching installation declination and the horizontal installation declination of the radar according to the first relative rotation matrix rotating to the third speed information by the second speed information and the second relative rotation matrix rotating to the vehicle body coordinate system by the radar coordinate system, and accordingly, the pitching installation declination and the horizontal installation declination of the radar can be calculated according to the relevant information in the vehicle running process such as the radar data and the inertial guidance information, and a calibration station is not required to be manually built to realize radar calibration, so that manpower and material resources are saved, and the calibration efficiency is improved.
In an implementation manner, since there is a random error in the installation declination for single-frame solution, in order to eliminate the random error of the system, as shown in fig. 4, the embodiment of the present application provides the following method:
s210: and acquiring the absolute stationary point cloud from the current frame radar point cloud according to the first speed information of each point cloud in the current frame radar point cloud under the vehicle body coordinate system and the second speed information of the reference stationary point cloud under the vehicle body coordinate system.
S220: and calculating third speed information of the reference static point cloud under the radar coordinate system when the loss function takes the minimum value.
S230: and determining the pitching installation declination and the horizontal installation declination of the radar according to the first relative rotation matrix rotating from the second speed information to the third speed information and the second relative rotation matrix rotating from the radar coordinate system to the vehicle body coordinate system.
S240: generating a first vector based on M pitching installation declination angles corresponding to continuous M frames of radar point clouds, and generating a second vector based on M horizontal installation declination angles corresponding to the continuous M frames of radar point clouds.
Wherein M is a positive integer.
S250: histogram-counting the first vector and the second vector to obtain at least one mode of the pitch stagger angle and at least one mode of the horizontal stagger angle.
Wherein the first vector theta x ＝[θ x1 θ x2 … θ xm ]Second vector theta z ＝[θ z1 θ z2 … θ zm ]。
S260: determining an average of at least one mode of the pitch stagger angle as a final desired pitch stagger angle, and determining an average of at least one mode of the horizontal stagger angle as a final desired horizontal stagger angle.
The mode is a value that appears most frequently in a set of data, and sometimes there may be a plurality of values that appear most frequently in a set of data, so the final desired pitch stagger angle and horizontal stagger angle can be found by calculating the average of at least one mode of the pitch stagger angle and the average of at least one mode of the horizontal stagger angle.
Based on the foregoing embodiments, an embodiment of the present application provides a radar calibration apparatus, as shown in fig. 5, the apparatus includes:
the acquisition unit 30 is configured to acquire an absolute stationary point cloud from a current frame radar point cloud according to first speed information of each point cloud in the current frame radar point cloud in an automobile body coordinate system and second speed information of a reference stationary point cloud in the automobile body coordinate system;
the calculation unit 32 is configured to calculate third speed information of the reference stationary point cloud in the radar coordinate system when a loss function takes a minimum value, where the loss function is established according to a radial speed, an azimuth angle, and a pitch angle of the absolute stationary point cloud in the radar coordinate system;
a determining unit 34, configured to determine a pitch installation declination and a horizontal installation declination of the radar according to a first relative rotation matrix of the second speed information rotating to the third speed information and a second relative rotation matrix of the radar coordinate system rotating to the vehicle body coordinate system.
In one embodiment, the first speed information includes the speed of each point cloud in the current frame radar point cloud on the y-axis of the vehicle body coordinate system, and the second speed information includes the speed of the reference stationary point cloud on the y-axis of the vehicle body coordinate system;
an acquisition unit 30, comprising:
the calculation module is used for respectively calculating the ratio of the speed of each point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system to the speed of the reference static point cloud on the y axis of the vehicle body coordinate system;
and the determining and acquiring module is used for determining the point cloud with the ratio smaller than a preset ratio threshold in the current frame radar point cloud as an absolute static point cloud and acquiring the absolute static point cloud from the current frame radar point cloud.
In one embodiment, the second velocity information further includes velocity magnitudes of the reference stationary point cloud on x-axis and z-axis of the vehicle body coordinate system;
the calculation module is further used for calculating the speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system according to the vehicle speed, the angular speed of the vehicle under the vehicle body coordinate system and the deviation of the radar coordinate system relative to the vehicle body coordinate system corresponding to the current frame radar point cloud respectively before the ratio of the speed of each point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system to the speed of the reference stationary point cloud on the y axis of the vehicle body coordinate system is calculated respectively;
the acquisition unit 30 further includes:
the negation module is used for respectively negating the speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system to obtain the speed of the reference stationary point cloud on the x axis, the y axis and the z axis of the radar coordinate system;
and the calculation module is also used for calculating the speed of the point cloud to be calculated on the y axis of the vehicle body coordinate system according to the azimuth angle of the point cloud to be calculated under the radar coordinate system, the pitch angle of the point cloud to be calculated under the radar coordinate system, the radial speed of the point cloud to be calculated under the radar coordinate system and the speed of the reference static point cloud on the x axis and the z axis of the vehicle body coordinate system.
In one embodiment, a computing module for
Calculating the speed of the radar on the x axis, the y axis and the z axis of the body coordinate system according to the following formula:
wherein the content of the first and second substances,
and
respectively represents the speed magnitude, omega, of the radar on the x axis, the y axis and the z axis of the body coordinate system x 、ω y And ω z The angular speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system is respectively represented, RadarX, RadarY and RadarZ represent the deviation of the radar coordinate system on the x axis, the y axis and the z axis relative to the vehicle body coordinate system, and Vehiclespeed represents the speed of the vehicle when the radar point cloud of the current frame is generated.
In one embodiment, a computing module for
Calculating the speed of the ith point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system according to the following formula
Wherein the content of the first and second substances,
the radial speed of the ith point cloud under the radar coordinate system is represented,
respectively representing the speed of the reference stationary point cloud on the x axis and the z axis of the vehicle body coordinate system, theta i An azimuth angle of the ith point cloud in the radar coordinate system,
Representing the ith point cloud in the mineTo the pitch angle under the coordinate system.
In one embodiment, the third velocity information includes velocity magnitudes of the reference stationary point cloud in x, y, and z axes of the radar coordinate system, and the loss function is established based on a least square method, and the loss function is:
wherein, theta 1 、θ 2 …θ N Respectively representing the azimuth angles of different point clouds in the current frame radar point cloud under the radar coordinate system,
respectively representing the pitch angles of different point clouds in the current frame radar point cloud under the radar coordinate system,
and
respectively representing the velocity of the point cloud on the x-axis, y-axis and z-axis of the radar coordinate system, and when the loss function takes the minimum value,
and
respectively representing the velocity magnitudes of the reference stationary point cloud on the x-axis, y-axis and z-axis of the radar coordinate system,
respectively representing the radial speed of each absolute stationary point cloud under the radar coordinate system, wherein N is the number of the absolute stationary point clouds in the radar point cloud of the current frame;
a calculating unit 32 for calculating the j absolute stationary point cloud at the radar seat according to the following formulaMagnitude of radial velocity under the scale
Wherein, theta j Representing the azimuth angle of the j-th absolute static point cloud in the current frame radar point cloud under the radar coordinate system,
and representing the pitch angle of the jth absolute static point cloud in the current frame radar point cloud under the radar coordinate system.
In one embodiment, the second velocity information includes velocity magnitudes of the reference stationary point cloud on an x-axis, a y-axis, and a z-axis of the body coordinate system, and the third velocity information includes velocity magnitudes of the reference stationary point cloud on the x-axis, the y-axis, and the z-axis of the radar coordinate system;
the determining unit 34 is further configured to calculate an included angle between a first speed vector and a second speed vector, where the first speed vector is generated according to the speed of the reference stationary point cloud in the second speed information on the x-axis, the y-axis, and the z-axis of the vehicle coordinate system, and the second speed vector is generated according to the speed of the reference stationary point cloud in the third speed information on the x-axis, the y-axis, and the z-axis of the radar coordinate system; calculating an antisymmetric matrix of unit axes of rotation of the first velocity vector and the second velocity vector; calculating the first relative rotation matrix according to a Rodrigues rotation formula, the included angle and the antisymmetric matrix.
In one embodiment of the method of the present invention,
the second relative rotation matrix
Wherein, theta x For the radar coordinate system to rotate towards the body coordinate systemAngle of rotation about the x-axis, theta z Is the angle of rotation about the z-axis of the radar coordinate system when rotated towards the body coordinate system.
In an embodiment, the obtaining unit 30 is configured to, when a vehicle speed corresponding to the current frame radar point cloud is greater than a preset vehicle speed threshold, obtain an absolute stationary point cloud from the current frame radar point cloud according to first speed information of each point cloud in the current frame radar point cloud in a vehicle body coordinate system and second speed information of a reference stationary point cloud in the vehicle body coordinate system;
and/or the presence of a gas in the gas,
a calculating unit 32, configured to calculate third speed information of the reference stationary point cloud in the radar coordinate system when the loss function takes the minimum value under the condition that the number of the absolute stationary point clouds is greater than a preset number threshold.
In one embodiment, the apparatus further comprises:
the device comprises a generating unit and a calculating unit, wherein the generating unit is used for generating a first vector based on M pitching installation declination angles corresponding to continuous M frames of radar point clouds and generating a second vector based on M horizontal installation declination angles corresponding to the continuous M frames of radar point clouds, and M is a positive integer;
a statistical unit, configured to perform histogram statistics on the first vector and the second vector to obtain at least one mode of the pitch installation deflection angle and at least one mode of the horizontal installation deflection angle;
a determining unit 34, further configured to determine an average of at least one mode of the pitch stagger angle as a final required pitch stagger angle, and determine an average of at least one mode of the horizontal stagger angle as a final required horizontal stagger angle.
Based on the above method embodiments, another embodiment of the present application provides a storage medium having stored thereon executable instructions, which when executed by a processor, cause the processor to implement the method of any of the above method embodiments.
Based on the foregoing method embodiment, another embodiment of the present application provides an electronic device, including: one or more processors;
a storage device to store one or more programs,
wherein the one or more programs, when executed by the one or more processors, cause the one or more processors to implement a method as in any one of the method embodiments described above.
The system and apparatus embodiments correspond to the method embodiment, and have the same technical effects as the method embodiment, and for the specific description, reference is made to the method embodiment. The device embodiment is obtained based on the method embodiment, and for specific description, reference may be made to the method embodiment section, which is not described herein again. Those of ordinary skill in the art will understand that: the figures are merely schematic representations of one embodiment, and the blocks or processes in the figures are not necessarily required to practice the present application.
Those of ordinary skill in the art will understand that: modules in the devices in the embodiments may be distributed in the devices in the embodiments according to the description of the embodiments, or may be located in one or more devices different from the embodiments with corresponding changes. The modules of the above embodiments may be combined into one module, or further split into multiple sub-modules.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (10)
1. A method of radar calibration, the method comprising:
acquiring absolute stationary point clouds from current frame radar point clouds according to first speed information of each point cloud in the current frame radar point clouds under an automobile body coordinate system and second speed information of reference stationary point clouds under the automobile body coordinate system;
calculating third speed information of the reference static point cloud under the radar coordinate system when a loss function takes the minimum value, wherein the loss function is established according to the radial speed, the azimuth angle and the pitch angle of the absolute static point cloud under the radar coordinate system;
and determining the pitching installation declination and the horizontal installation declination of the radar according to a first relative rotation matrix rotating from the second speed information to the third speed information and a second relative rotation matrix rotating from the radar coordinate system to the vehicle body coordinate system.
2. The method of claim 1, wherein the first velocity information comprises a velocity magnitude of each point cloud in the current frame radar point cloud on the y-axis of the body coordinate system, and the second velocity information comprises a velocity magnitude of the reference stationary point cloud on the y-axis of the body coordinate system;
acquiring absolute stationary point clouds from current frame radar point clouds according to first speed information of each point cloud in the current frame radar point clouds under an automobile body coordinate system and second speed information of reference stationary point clouds under the automobile body coordinate system, wherein the method comprises the following steps:
respectively calculating the ratio of the speed of each point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system to the speed of the reference static point cloud on the y axis of the vehicle body coordinate system;
and determining the point cloud with the ratio smaller than a preset ratio threshold value in the current frame radar point cloud as an absolute static point cloud, and acquiring the absolute static point cloud from the current frame radar point cloud.
3. The method of claim 2, wherein the second velocity information further comprises a velocity magnitude of the reference stationary point cloud on an x-axis, a z-axis of the body coordinate system;
before respectively calculating the ratio of the speed of each point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system to the speed of the reference stationary point cloud on the y axis of the vehicle body coordinate system, the method further comprises:
calculating the speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system according to the vehicle speed, the angular speed of the vehicle under the vehicle body coordinate system and the deviation of the radar coordinate system relative to the vehicle body coordinate system respectively corresponding to the radar point cloud of the current frame;
respectively negating the speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system to obtain the speed of the reference stationary point cloud on the x axis, the y axis and the z axis of the radar coordinate system;
and aiming at the point cloud to be calculated in the current frame radar point cloud, calculating the speed of the point cloud to be calculated on the y axis of the vehicle body coordinate system according to the azimuth angle of the point cloud to be calculated under the radar coordinate system, the pitch angle of the point cloud to be calculated under the radar coordinate system, the radial speed of the point cloud to be calculated under the radar coordinate system and the speed of the reference static point cloud on the x axis and the z axis of the vehicle body coordinate system.
4. The method of claim 3, wherein calculating the speed of the radar on the x-axis, the y-axis and the z-axis of the vehicle body coordinate system according to the vehicle speed, the angular speed of the vehicle under the vehicle body coordinate system and the deviation of the radar coordinate system relative to the vehicle body coordinate system respectively corresponding to the radar point clouds of the current frame comprises:
calculating the speed of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system according to the following formula:
wherein the content of the first and second substances,
and
respectively represents the speed magnitude, omega, of the radar on the x axis, the y axis and the z axis of the body coordinate system x 、ω y And omega z And the angular velocity, RadarX, RadarY and RadarZ of the radar on the x axis, the y axis and the z axis of the vehicle body coordinate system respectively represent the deviation of the radar coordinate system relative to the x axis, the y axis and the z axis of the vehicle body coordinate system, and the Vehiclespeed represents the velocity of the vehicle when the current frame radar point cloud is generated.
5. The method of claim 3, wherein for the point cloud to be calculated in the current frame radar point cloud, calculating the velocity of the point cloud to be calculated in the y axis of the vehicle body coordinate system according to the azimuth angle of the point cloud to be calculated in the radar coordinate system, the pitch angle of the point cloud to be calculated in the radar coordinate system, the radial velocity of the point cloud to be calculated in the radar coordinate system, and the velocity of the reference stationary point cloud in the x axis and the z axis of the vehicle body coordinate system, comprises:
calculating the speed of the ith point cloud in the current frame radar point cloud on the y axis of the vehicle body coordinate system according to the following formula
Wherein, the first and the second end of the pipe are connected with each other,
the radial velocity magnitude of the ith point cloud under the radar coordinate system is represented,
respectively representing the speed of the reference stationary point cloud on the x axis and the z axis of the vehicle body coordinate system, theta i Indicating the azimuth angle of the ith point cloud under the radar coordinate system,
And representing the pitch angle of the ith point cloud under the radar coordinate system.
6. The method of claim 1, wherein the third velocity information comprises velocity magnitudes of the reference stationary point cloud in x, y, and z axes of the radar coordinate system, and wherein the loss function is established based on a least squares method, the loss function being:
wherein, theta 1 、θ 2 …θ N Respectively representing azimuth angles of different point clouds in the current frame radar point cloud under the radar coordinate system,
respectively representing the pitch angles of different point clouds in the current frame radar point cloud under the radar coordinate system,
and
respectively representing the velocity of the point cloud on the x-axis, y-axis and z-axis of the radar coordinate system, and when the loss function takes the minimum value,
and
respectively representing the velocity magnitudes of the reference stationary point cloud on the x-axis, y-axis and z-axis of the radar coordinate system,
respectively representing the radial speed of each absolute stationary point cloud under the radar coordinate system, wherein N is the number of the absolute stationary point clouds in the radar point cloud of the current frame;
calculating the radial speed of the jth absolute stationary point cloud under the radar coordinate system according to the following formula
Wherein, theta j Representing an azimuth angle of a j-th absolute stationary point cloud in the current frame radar point cloud under the radar coordinate system,
and representing the pitch angle of the jth absolute static point cloud in the current frame radar point cloud under the radar coordinate system.
7. The method of claim 1, wherein the second velocity information comprises velocity magnitudes of the stationary point cloud of reference on an x-axis, a y-axis, and a z-axis of the body coordinate system, and the third velocity information comprises velocity magnitudes of the stationary point cloud of reference on an x-axis, a y-axis, and a z-axis of the radar coordinate system;
the calculation method of the first relative rotation matrix comprises the following steps:
calculating an included angle between a first speed vector and a second speed vector, wherein the first speed vector is generated according to the speed of the reference static point cloud in the second speed information on the x axis, the y axis and the z of the vehicle body coordinate system, and the second speed vector is generated according to the speed of the reference static point cloud in the third speed information on the x axis, the y axis and the z of the radar coordinate system;
calculating an antisymmetric matrix of unit axes of rotation of the first velocity vector and the second velocity vector;
calculating the first relative rotation matrix from the Rodrigues rotation formula, the included angle, and the antisymmetric matrix.
8. The method of claim 1,
the second relative rotation matrix
Wherein, theta x Is the angle of rotation, theta, about the x-axis of rotation of the radar coordinate system to the body coordinate system z Is the angle of rotation about the z-axis of the radar coordinate system when rotated towards the body coordinate system.
9. The method of claim 1, wherein obtaining absolute stationary point clouds from current frame radar point clouds according to first speed information of each point cloud in the current frame radar point clouds under a vehicle body coordinate system and second speed information of reference stationary point clouds under the vehicle body coordinate system comprises: under the condition that the vehicle speed corresponding to the current frame radar point cloud is greater than a preset vehicle speed threshold value, acquiring an absolute stationary point cloud from the current frame radar point cloud according to first speed information of each point cloud in the current frame radar point cloud under a vehicle body coordinate system and second speed information of a reference stationary point cloud under the vehicle body coordinate system;
and/or calculating third speed information of the reference stationary point cloud under the radar coordinate system when the loss function takes the minimum value, wherein the third speed information comprises the following steps: and under the condition that the number of the absolute static point clouds in the current frame radar point cloud is larger than a preset number threshold, calculating third speed information of the reference static point cloud under the radar coordinate system when the loss function takes the minimum value.
10. The method according to any one of claims 1-9, further comprising:
generating a first vector based on M pitching installation declination angles corresponding to continuous M frames of radar point clouds, and generating a second vector based on M horizontal installation declination angles corresponding to the continuous M frames of radar point clouds, wherein M is a positive integer;
performing histogram statistics on the first vector and the second vector to obtain at least one mode of the pitch declination and at least one mode of the horizontal declination;
determining an average of at least one mode of the pitch stagger angle as a final desired pitch stagger angle, and determining an average of at least one mode of the horizontal stagger angle as a final desired horizontal stagger angle.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115201773A (en) * | 2022-09-13 | 2022-10-18 | 长沙莫之比智能科技有限公司 | Vehicle-mounted millimeter wave radar installation angle error correction method based on point cloud speed |
| CN118011345A (en) * | 2024-04-08 | 2024-05-10 | 深圳信息职业技术学院 | On-line calibration method for vehicle millimeter wave radar |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115201773A (en) * | 2022-09-13 | 2022-10-18 | 长沙莫之比智能科技有限公司 | Vehicle-mounted millimeter wave radar installation angle error correction method based on point cloud speed |
| CN115201773B (en) * | 2022-09-13 | 2022-12-13 | 长沙莫之比智能科技有限公司 | Vehicle-mounted millimeter wave radar installation angle error correction method based on point cloud speed |
| WO2024055991A1 (en) * | 2022-09-13 | 2024-03-21 | 长沙莫之比智能科技有限公司 | Point cloud speed-based error correction method for installation angle of vehicle-mounted millimeter wave radar |
| CN118011345A (en) * | 2024-04-08 | 2024-05-10 | 深圳信息职业技术学院 | On-line calibration method for vehicle millimeter wave radar |
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