Anechoic Radar Calibration Method and Equipment Based on LiDAR Point Clouds

Abstract

This application discloses a method and device for anechoic chamber radar calibration based on lidar point clouds, relating to the field of radar calibration technology, and used to at least improve the accuracy of radar calibration. The method includes performing at least one round of radar calibration operations on the set calibration space until the radar calibration termination condition is met. In each round of radar calibration operations: acquiring the calibration object point cloud and at least one reference target point cloud in the calibration space; further calibrating the first relative position between the target radar and the turntable based on the at least one reference target point cloud; and calibrating the second relative position between the calibration object and the target radar based at least on the calibration object point cloud. The reference target point cloud is point cloud data collected from one or more targets among the anechoic chamber walls, the target radar, and the metal plate.

Description

Technical Field

[0001] This application relates to the field of radar calibration technology, and in particular to a method and device for anechoic chamber radar calibration based on lidar point clouds. Background Technology

[0002] In general, anechoic chamber testing systems are often used during radar testing and calibration. The radar is placed in an anechoic chamber, and when calibrating the radar using a reflecting target, the radar is usually mounted on an electromechanical fixture with two degrees of freedom of rotation at one end of the anechoic chamber, and the reflecting target is placed at the other end. By controlling the change of the fixture angle, the radio frequency signals emitted by the radar at different angles and returned from the reflecting target are collected, analyzed, and used to calibrate the radar. However, in existing technologies, the accuracy of radar calibration is often severely affected by the clamping angle deviation between the radar and the turntable. Summary of the Invention

[0003] This application provides a method for anechoic chamber radar calibration based on lidar point clouds, which is used to at least improve the accuracy of radar installation and calibration.

[0004] In a first aspect, this application provides a method for anechoic chamber radar calibration based on lidar point clouds, the method comprising:

[0005] The calibration space is configured with at least one round of radar calibration operations until the radar calibration termination conditions are met. The calibration space is configured as follows: a turntable and a calibration object are placed in an anechoic chamber, and the target radar is fixed to the turntable using a metal plate, forming a fixed structure with the target radar, turntable, and metal plate. A lidar is placed between the calibration object and the target radar. Each round of the radar calibration operation includes steps S1 to S3.

[0006] Step S1: Acquire a point cloud of the calibration object and a point cloud of at least one reference target using a lidar. The reference target point cloud is point cloud data collected from one or more targets among the darkroom walls, target radar, and metal plate of the darkroom.

[0007] Step S2: Based on the at least one reference target point cloud, calibrate the first relative position between the target radar and the turntable;

[0008] Step S3: Based at least on the point cloud of the calibration object, calibrate the second relative position between the calibration object and the target radar.

[0009] In the method provided in this application, in each round of radar calibration operation, the first relative position between the target radar and the turntable is adjusted based on the reference target point cloud collected by the lidar, which improves the accuracy of the clamping angle between the target radar and the turntable, thereby improving the accuracy of calibration. Subsequently, based on the calibration object point cloud collected by the lidar, the second relative position between the calibration object and the target radar is calibrated, which improves the accuracy of the relative position between the calibration object and the target radar, thereby improving the accuracy of radar calibration.

[0010] In one possible implementation, the at least one reference target point cloud includes a wall point cloud acquired for the walls of the darkroom and a radar point cloud acquired for the target radar.

[0011] The calibration of the first relative position between the target radar and the turntable based on the at least one reference target point cloud includes:

[0012] Based on the wall point cloud, a normal vector perpendicular to the wall of the darkroom is constructed as a first reference vector; and, at least based on the radar point cloud, a normal vector perpendicular to the radar plane of the target radar is constructed as a second reference vector.

[0013] Based on the first reference vector and the second reference vector, it is determined whether the first relative position adjustment condition is met; the first relative position adjustment condition is that the horizontal angle and the pitch angle between the first reference vector and the second reference vector are both preset values;

[0014] If the first relative position adjustment condition is met, the clamping degree of the target radar and the metal plate is adjusted, and the process proceeds to step S3; if the first relative position adjustment condition is not met, the process proceeds directly to step S3.

[0015] In one possible implementation, the target radar and the metal plate are secured together by multiple loosely fasteners at different locations; adjusting the clamping degree between the target radar and the metal plate includes:

[0016] The first relative position of the target radar and the metal plate is adjusted by adjusting the tightness of the loose and fasteners at the off-center position of the target radar and the metal plate, wherein the off-center position is a position outside the center position of the metal plate.

[0017] In one possible implementation, constructing a first reference vector based on the wall point cloud and perpendicular to the darkroom wall includes:

[0018] Perform singular value decomposition on the point cloud on the wall;

[0019] Based on the singular value decomposition results, a normal vector perpendicular to the wall of the darkroom is constructed as the first reference vector.

[0020] In one possible implementation, the step of constructing a normal vector perpendicular to the radar plane of the target radar, based at least on radar point clouds, as a second reference vector includes:

[0021] A second reference vector is constructed based on the radar point cloud, with a normal vector perpendicular to the radar plane. The starting point and direction of the second reference vector are determined based on the radar point cloud; or

[0022] The at least one reference target point cloud also includes a metal plate point cloud collected for the metal plate. Based on the radar point cloud and the metal plate point cloud, a normal vector perpendicular to the radar plane of the target radar is constructed as a second reference vector. The starting point of the second reference vector is determined based on the radar point cloud, and the direction of the second reference vector is determined based on the metal plate point cloud.

[0023] In one possible implementation, the calibration of the second relative position between the calibration object and the target radar, based at least on the calibration object point cloud, includes:

[0024] The center of the calibration object is determined based on the point cloud of the calibration object;

[0025] The inverse vector of the first reference vector, drawn through the center of the calibration object, is the third reference vector;

[0026] Determine whether the third reference vector satisfies the second relative position calibration condition; the second relative position calibration condition is that the extension line of the third reference vector or the third reference vector passes through the center point of the target radar;

[0027] If the third reference vector satisfies the second relative position calibration condition, the placement of the calibrator is adjusted; if the third reference vector does not satisfy the second relative position calibration condition, the calibration of the second relative position is completed.

[0028] In one possible implementation, before performing at least one round of radar calibration operations on the set calibration space until the radar calibration termination condition is met, the method further includes:

[0029] Point clouds of the turntable are collected using lidar.

[0030] The rotation center of the turntable is determined by the turntable point cloud;

[0031] The center position of the metal plate is fixed at the rotation center; and the radar is fixed to the metal plate through the non-center position of the metal plate.

[0032] In one possible implementation, after performing at least one round of radar calibration operations on the set calibration space until the radar calibration termination condition is met, the method further includes:

[0033] Based on the point cloud of the calibration object and the point cloud of the radar, the distance between the center points of the calibration object and the target radar is determined;

[0034] The calibration object is set at preset coordinates in the radar coordinate system corresponding to the target radar, where the preset coordinates are (spacing, 0, 0).

[0035] Secondly, the embodiments of this application provide an anechoic chamber radar calibration method based on lidar point clouds, applied to an automated calibration analysis unit, comprising:

[0036] The calibration space is configured with at least one round of radar calibration operations until the radar calibration termination conditions are met. The calibration space is configured as follows: a turntable and a calibration object are placed in an anechoic chamber, and the target radar is fixed to the turntable using a metal plate, forming a fixed structure with the target radar, turntable, and metal plate. A lidar is placed between the calibration object and the target radar. Each round of radar calibration operations includes:

[0037] The point cloud of the calibration object and at least one reference target are acquired by the lidar, wherein the reference target point cloud is point cloud data acquired from one or more targets among the darkroom walls, target radar, and metal plate.

[0038] The calibration space adjustment instruction information is displayed on the display terminal to notify the user to adjust the calibration space; wherein,

[0039] The adjustment instruction information is obtained by processing at least one of the calibration point cloud and the reference target point cloud. The adjustment instruction information includes first adjustment information for a first relative position and / or second adjustment information for a second relative position. The first relative position is the relative position between the target radar and the turntable, and the second relative position is the relative position between the calibration object and the target radar.

[0040] The method provided in this application can process the calibration object point cloud and reference target point cloud collected by lidar through computer equipment in each round of radar calibration operation. Then, it can directly inform the calibration personnel of the relevant first adjustment information and / or second adjustment information through the display terminal, so that the personnel can adjust the first relative position and / or second relative position in a timely and accurate manner, thereby improving the accuracy and convenience of radar calibration.

[0041] In one possible implementation, when the adjustment instruction information includes first adjustment information, the calibration space is adjusted by adjusting the clamping degree between the target radar and the metal plate;

[0042] When the adjustment instruction information includes the second adjustment information, the calibration space is adjusted by adjusting the placement of the calibration object.

[0043] In one possible implementation, the first adjustment information includes first indication information and / or second indication information.

[0044] The first indication information is an indication of whether to adjust the first relative position;

[0045] The second indication information includes the horizontal angle and the pitch angle between the first reference vector and the second reference vector; the first reference vector is a normal vector perpendicular to the wall of the darkroom, and the first reference vector is constructed based on the point cloud of the wall; the second reference vector is a normal vector perpendicular to the radar plane of the target radar, and the second reference vector is constructed based on the radar point cloud.

[0046] In one possible implementation, the second adjustment information includes third indication information and / or fourth indication information;

[0047] The third indication information includes an indication of whether to adjust the second relative position;

[0048] The fourth indication information is the extension of the third reference vector or the positional distribution of the third reference vector and the target radar; the third reference vector is the inverse vector of the first reference vector, and the third reference vector passes through the center of the calibration object, and the first reference vector is the normal vector perpendicular to the wall of the darkroom.

[0049] Thirdly, embodiments of this application also provide a darkroom radar calibration device based on lidar point clouds. The device includes a processor and a memory. The memory is used to store programs executable by the processor, and the processor is used to read the programs in the memory and execute any of the methods described in the first or second aspect of this application.

[0050] Fourthly, embodiments of this application also provide a computer storage medium having a computer program stored thereon, which, when executed by a processor, is used to implement the steps of the methods described in the first or second aspect above.

[0051] These or other aspects of this application will become more apparent in the following description of embodiments. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This application provides a schematic diagram of a radar calibration scenario in the prior art.

[0054] Figure 2 A schematic diagram of a calibration space provided for an embodiment of this application;

[0055] Figure 3 A flowchart of an anechoic chamber radar calibration method based on lidar point clouds provided in this application embodiment;

[0056] Figure 4 A flowchart illustrating the calibration of the first relative position between a target radar and a turntable, provided as an embodiment of this application;

[0057] Figure 5 A schematic diagram of a reference vector provided for an embodiment of this application;

[0058] Figure 6 A flowchart illustrating the calibration of a second relative position between a calibration object and a target radar, provided as an embodiment of this application;

[0059] Figure 7 A schematic diagram of another reference vector provided in an embodiment of this application;

[0060] Figure 8 A flowchart illustrating another anechoic chamber radar calibration method based on lidar point clouds provided in this application embodiment;

[0061] Figure 9 A schematic diagram of the structure of an anechoic chamber radar calibration device provided in an embodiment of this application;

[0062] Figure 10 A schematic diagram of another anechoic chamber radar calibration device provided in the embodiments of this application;

[0063] Figure 11 This is a schematic diagram of the structure of an anechoic chamber radar calibration device provided in an embodiment of this application. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0065] In the embodiments of this application, the term "and / or" describes the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. The character " / " generally indicates that the preceding and following associated objects have an "or" relationship.

[0066] The application scenarios described in this application are for the purpose of more clearly illustrating the technical solutions of this application, and do not constitute a limitation on the technical solutions provided in this application. Those skilled in the art will understand that with the emergence of new application scenarios, the technical solutions provided in this application are also applicable to similar technical problems. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0067] First, let's explain the key terms in the embodiments of this application:

[0068] Target radar: In the embodiments of this application, target radar refers to the radar that needs to be calibrated. Target radar may be, but is not limited to, millimeter-wave radar.

[0069] The lidar used in this embodiment can be a lidar with a large number of beams, such as a 64-beam lidar or a 128-beam lidar.

[0070] Calibration object: refers to a structural device or equipment that has a strong reflective effect on the electromagnetic waves emitted by the radar. The shape and type of the calibration object in the embodiments of this application are not limited. The calibration object can be, but is not limited to, a square, triangular, fan-shaped, etc. The calibration object can also be an active or passive calibration object, and can also be a two-sided reflector or a three-sided reflector, etc.

[0071] Please refer to Figure 1 In existing technologies, radar calibration is performed using a level and a simple laser rangefinder. This method involves calibrating the tilt angle of the turntable using a level, then directly clamping the radar onto the turntable. The bottom vertical surface of the laser rangefinder is then aligned with the radar shield, and the emitted laser beam is used to locate the calibration object. However, this method introduces the following problems:

[0072] 1) Large clamping error

[0073] Each time the radar is clamped, it introduces clamping angle error and radar offset error to the rotation center;

[0074] 2) Poor accuracy

[0075] Due to the unevenness of the radar shield, when the bottom of the rangefinder is attached to it, the local burrs and protrusions will cause horizontal and pitch angle errors. At the same time, when the rangefinder is manually attached to the radar surface, there will also be a slight shaking error, which will cause the placement of the calibration object to deviate from the ideal value and affect the final calibration accuracy.

[0076] 3) Inconsistent calibration results

[0077] Because the angle at which the radar is clamped varies slightly each time, the calibration results of the same radar after repeated clamping will also have slight differences, and consistency cannot be guaranteed.

[0078] 4) Cumbersome operation

[0079] Each calibration requires fine-tuning the radar clamping angle and the placement of the calibration object. If an analog signal source is used, the angle of the signal source transmitter must also be adjusted to ensure that it is perpendicular to the radar plane.

[0080] In view of this, embodiments of this application provide a lidar anechoic chamber calibration method. In each round of radar calibration operation, the first relative position between the target radar and the turntable is adjusted based on the reference target point cloud, which improves the accuracy of the clamping angle between the target radar and the turntable. Subsequently, the second relative position between the calibration object and the target radar is calibrated based on the calibration object point cloud, which improves the accuracy of the relative position between the calibration object and the target radar, thereby improving the accuracy of radar calibration.

[0081] The following provides a detailed description of the anechoic chamber radar calibration method based on lidar point clouds provided in the embodiments of this application. Firstly, before performing lidar anechoic chamber calibration, the calibration space can be set up. Please refer to... Figure 2 The calibration space shown in (a) and (b) can be set up in the following way, but is not limited to: setting up a turntable 230, a calibration object 240 and a lidar 250 in a darkroom 210, and fixing the target radar 220 to the turntable 230 by means of a metal plate, so that the target radar 220, the turntable 230 and the metal plate form a fixed body (i.e., a rigid body), and setting up the lidar 250 between the calibration object 240 and the target radar 220. In Figure (b), a millimeter-wave radar is used as a specific example of the target radar 220.

[0082] Please refer to Figure 3 The anechoic chamber radar calibration method based on lidar point clouds performs at least one round of radar calibration operations on the set calibration space until the radar calibration termination condition is met, specifically including:

[0083] S310, confirm the start of calibration.

[0084] In this embodiment, the start of calibration is determined based on the actual situation. For example, calibration personnel can set up the calibration space and then start the calibration with a single button, or the calibration personnel can set up the calibration space and then start the calibration by rotating the turntable.

[0085] S320, perform at least one round of radar calibration operation, wherein one round of radar calibration operation includes the following steps S1 to S3.

[0086] Step S1: Acquire a point cloud of the calibration object and a point cloud of at least one reference target using a lidar. The reference target point cloud is point cloud data acquired from one or more targets among the darkroom walls, target radar, and metal plate.

[0087] Step S2: Based on the aforementioned reference target point cloud, calibrate the first relative position between the target radar and the turntable.

[0088] Step S3: Based at least on the calibration point cloud and the calibration point cloud, calibrate the second relative position between the calibration object and the target radar.

[0089] Step S330: Determine whether the radar calibration termination condition is met. If it is met, proceed to step S340; otherwise, re-enter step S320.

[0090] It should be noted that, in this embodiment, the radar calibration termination condition can be a combination of one or more conditions, such as confirming in step S2 that the first relative position does not need to be calibrated and / or confirming in step S3 that the second relative position does not need to be calibrated. For example, the radar calibration termination condition can be set as determining in step S2 that the first relative position does not need to be calibrated and determining in step S3 that the second relative position does not need to be calibrated. Furthermore, those skilled in the art can flexibly set the above radar calibration termination condition according to the actual business needs of radar calibration, and this embodiment does not impose any restrictions on this.

[0091] Step S340: Complete the radar calibration operation.

[0092] Please continue reading Figure 3 As one embodiment, step S340 may include, but is not limited to, the following steps S3401 and S3402:

[0093] Step S3401: Based on the calibration point cloud and the radar point cloud, determine the distance R between the center points of the calibration object and the target radar;

[0094] Step S3402: Set the calibration object at the preset coordinates (R, 0, 0) of the radar coordinate system corresponding to the target radar, and the calibration ends.

[0095] Further reading is available upon request. Figure 2 and Figure 3 In the prior art, each time the radar is calibrated, it is necessary to spend time readjusting the position of the calibration space for environmental calibration. However, in the embodiment of this application, the target radar 220 is mounted on a metal plane and then the metal plane is clamped on the turntable 230, so that the target radar 220 and the turntable 230 form a complete rigid body. Only the metal plane needs to be calibrated once. When the high-beam radar is calibrated multiple times, there is no need to adjust the clamping angle and position of the metal plane, which ensures the consistency of the calibration results. That is, in the embodiment of this application, only the lidar 250 needs to be calibrated once, and the target radar 220 can be clamped on and used afterward.

[0096] As one example, please continue to see Figure 3 After determining the start of calibration in step 310 and before performing the first round of radar calibration in step S320, the metal plate can be fixed onto the turntable through the following steps S3101 to S3103.

[0097] Step S3101: Collect point cloud data of the turntable using lidar.

[0098] Step S3102: Determine the rotation center of the turntable by using the turntable point cloud.

[0099] Step S3103: Fix the center position of the metal plate to the rotation center; and fix the radar to the metal plate through the non-center position of the metal plate.

[0100] Specifically, in this embodiment, the metal plate and turntable can be fixed using, but is not limited to, multiple threaded holes or bolts and other loosely fasteners. This allows the turntable's rotation center to be determined via the turntable point cloud during steps S3101 to S3103. The metal plate with threaded holes is then clamped to the turntable's rotation center, eliminating central axis offset errors. The target radar is then fixed to the metal plate using these loosely fasteners. Simultaneously, the turntable, metal plate, and target radar are integrated into a rigid body, eliminating random errors caused by multiple clamping operations and repeated radar clamping, thus preventing inconsistent calibration results for the same radar.

[0101] The following description of an embodiment of this application further illustrates a round of radar calibration operations.

[0102] Please refer to Figure 4As one embodiment, the at least one reference target point cloud acquired in step S1 may include a wall point cloud acquired for the anechoic chamber wall and a radar point cloud acquired for the target radar. The aforementioned anechoic chamber wall may be, but is not limited to, a location in the anechoic chamber facing away from the turntable. The anechoic chamber wall may be a reference point for... Figure 2 The darkroom reference plane shown in (b) can then include steps S410 to S440 in step S2.

[0103] Step S410: Based on the wall point cloud, construct the first reference vector a, which is a normal vector perpendicular to the wall of the darkroom.

[0104] As one embodiment, in step S410, singular value decomposition (SVD) can be performed on the wall point cloud, and based on the decomposition results, a normal vector perpendicular to the darkroom wall can be constructed as the first reference vector a; please refer to [the documentation] for details. Figure 5 The first reference vector 'a' can be a vector originating from the wall point cloud 510 and pointing to the calibration point cloud 520. The calibration point cloud 520 is a point cloud collected for the calibration object. The wall of the darkroom refers to the wall directly opposite the turntable (see details). Figure 2 ).

[0105] Step S420: Based at least on the radar point cloud, construct the normal vector of the radar plane perpendicular to the target radar as the second reference vector b.

[0106] As one embodiment, in step S420, a second reference vector b, a normal vector perpendicular to the radar plane, can be constructed based on the radar point cloud. The starting point and direction of the second reference vector b are determined based on the radar point cloud of the target radar. Please continue to refer to... Figure 5 The second reference vector b can be a vector that starts from the center of the radar point cloud 530 and points to the calibration point cloud 520. The second reference vector b is perpendicular to the radar plane, which can be understood as the outer surface of the shield of the target radar.

[0107] As one embodiment, the at least one reference target point cloud acquired in step S1 further includes a metal plate point cloud collected from the metal plate. Based on the radar point cloud and the metal plate point cloud, a normal vector perpendicular to the radar plane of the target radar is constructed as a second reference vector b. The starting point of the second reference vector b is determined based on the radar point cloud, and the direction of the second reference vector b is determined based on the metal plate point cloud; that is, please continue to refer to... Figure 5 The second reference vector b can be a vector that starts from the center of the metal plate point cloud and points to the calibration point cloud 520. The second reference vector b is perpendicular to the radar plane. Since the metal plate and the target radar are fixed together in this embodiment, the metal plate point cloud and the radar point cloud 530 shown in the figure are similar.

[0108] Step S430: Based on the first reference vector a and the second reference vector b, determine whether the first relative position adjustment condition is met. If it is met, proceed to step S440; otherwise, proceed directly to step S3. The first relative position adjustment condition is that the horizontal angle θ and the pitch angle Φ between the first reference vector a and the second reference vector b are both preset values. The preset values ​​can be set based on the value 0, and can be, but are not limited to, set to 0 or a value close to 0, to ensure that the first relative position calibration between the target radar and the turntable is accurate.

[0109] As one embodiment, this application does not limit the specific process for calculating the horizontal angle θ and pitch angle Φ between the first reference vector a and the second reference vector b. Those skilled in the art can set it according to actual needs, such as calculating the horizontal angle θ and pitch angle Φ between the first reference vector a and the second reference vector b in the following ways, but not limited to:

[0110] For the first reference vector 'a' in three-dimensional space, considering only its direction, 'a' can be expressed as [a x a y a z ], and |a|=1, the second reference vector b is processed in the same way; since a is used as a reference vector, it is transformed into a unit vector e=[0,1,0] through rotation transformation. Furthermore, to simplify the calculation, the above transformation can be represented by a quaternion q:

[0111] ①u=a×e;

[0112] ②θ=acos(a·e);

[0113] ③q(x, y, z, w) = [cos(θ / 2)sin(θ / 2)*u]; then the rotation matrix Rq can be derived from q.

[0114] ④Formula 4 is shown below:

[0115]

[0116] Therefore, we have: e = [0, 1, 0] = a·Rq;

[0117] After rotation, the second reference vector b is: b' = b·Rq = [b x b y b z ]; then the angle between e and b' in the horizontal direction is Azimuth = arctan(b x / b y ), pitch angle Elevation=arcsin(b zIf Azimuth is the horizontal angle θ between the first reference vector a and the second reference vector b, then the pitch angle Elevation is the pitch angle Φ between the first reference vector a and the second reference vector b.

[0118] Step S440: Adjust the clamping degree of the target radar and the metal plate, and proceed to step S3.

[0119] As one embodiment, in this application embodiment, the target radar and the aforementioned metal plate are fixed together by multiple loosely fastened fasteners at different positions; in step S440, the relative position of the target radar and the aforementioned metal plate can be adjusted by adjusting the tightness of the loosely fastened fasteners at the non-central positions of the target radar and the metal plate. The non-central position is a position other than the central position of the aforementioned metal plate. For ease of understanding, a threaded hole is used as a specific example of the aforementioned loosely fastened fastener. Since the target radar and the metal plate are fixed together by multiple threaded holes, the clamping degree of the target radar and the metal plate can be adjusted by adjusting the tightness of one or more threaded holes at the non-central positions of the target radar and the metal plate.

[0120] As one example, please refer to Figure 7 , Figure 6 , Figure 5 and Figure 3 The aforementioned step S3 can be achieved through the following steps S610 to S640:

[0121] Step S610: Determine the center of the calibration object based on the calibration object point cloud.

[0122] Step S620: Draw the inverse vector of the first reference vector through the center of the calibration object as the third reference vector (i.e., -a in the following text).

[0123] Step S630: Determine whether the third reference vector meets the second relative position calibration condition. If it does not meet the condition, proceed to step S640. If it does meet the condition, determine that the second relative position calibration is completed and proceed to the aforementioned step S330.

[0124] The second relative position calibration condition is the extension of the third reference vector -a (e.g., Figure 5 and Figure 6 The vector -λa, where λ is a value greater than 0, passes through the center point of the target radar, or the third reference vector -a passes through the center point of the target radar (e.g., ...). Figure 7 The indicated position is 700.

[0125] Step S640: Adjust the placement of the calibration object and proceed to the aforementioned step S330.

[0126] In step S640, the placement of the calibrator may include, but is not limited to, at least one of the height and horizontal positions of the calibrator, such as adjusting the height of the calibrator's support or the horizontal position of the calibrator.

[0127] As one example, please continue to see Figure 3 In this embodiment of the application, when calibrating the radar, the relative position between the target radar and the metal plate can be adjusted only after step S310 and before step S320 using the scheme of steps S3101 to S3103 (hereinafter referred to as Scheme 1) to eliminate random errors caused by inconsistent clamping angles of the target radar each time. In this embodiment of the application, when calibrating the radar, the first relative position between the target radar and the turntable can be calibrated only in step S2 of step S320 using the scheme of steps S410 to S440 (hereinafter referred to as Scheme 2), or the second relative position between the calibrator and the target radar can be calibrated in step S3 of step S320 using the scheme of steps S610 to S640 (hereinafter referred to as Scheme 3).

[0128] As one embodiment, in the process of installing and calibrating the radar, this application embodiment may simultaneously employ two or three of the aforementioned schemes 1, 2, and 3; and through the technical means of the aforementioned schemes 1, 2, and 3, at least the following technical effects can be achieved:

[0129] 1) Rapid calibration process: Traditional methods require repeated adjustments to the target radar clamping angle and target spatial position using a level and rangefinder before each radar test. The method in this application only requires collecting data for 2-3 seconds using a lidar and only requires spatial calibration once at the beginning of the use of the anechoic chamber. No further calibration is needed during subsequent tests. 2) Accurate calibration results: Traditional methods have an error of about 1° in the horizontal and pitch directions. The method in this application can control the error within 0.2°. 3) Ensure consistency: Eliminates random errors caused by inconsistent clamping angles each time.

[0130] Based on the same inventive concept, the aforementioned anechoic chamber radar calibration method based on lidar point clouds in the embodiments of this application can be executed by an automated calibration analysis unit in a computer device. The aforementioned computer device can be, but is not limited to, any device including terminal devices, independent physical servers, server clusters, or IoT control terminals. Furthermore, based on the premise that the aforementioned anechoic chamber radar calibration method based on lidar point clouds can be executed by an automated calibration analysis unit in a computer device, this automated calibration analysis unit can be, but is not limited to, implemented through a computer program. The embodiments of this application also provide an anechoic chamber radar calibration method based on lidar point clouds, applied to an automated calibration analysis unit; please refer to [link to relevant documentation]. Figure 8Specifically, it includes the following steps:

[0131] Step S800: Perform at least one round of radar calibration operation on the set calibration space until the radar calibration termination condition is met. The setting method of the calibration space and the radar calibration termination condition can be referred to the above content and will not be repeated here; each round of radar calibration operation includes steps S810 and S820:

[0132] Step S810 involves acquiring a point cloud of the calibration object and a point cloud of at least one reference target using a lidar. The reference target point cloud is point cloud data acquired from one or more targets among the darkroom walls, target radar, and metal plate. This is step S810 and the aforementioned... Figure 3 The steps are the same as S1 in the previous section.

[0133] Step S820: Display adjustment instruction information of the calibration space on the display terminal to notify the calibration space to be adjusted; wherein, the adjustment instruction information includes first adjustment information for a first relative position and / or second adjustment information for a second relative position, the first relative position being the relative position between the target radar and the turntable, the second relative position being the relative position between the calibration object and the target radar, and the adjustment instruction information being obtained by processing at least one of the calibration object point cloud and the reference target point cloud.

[0134] As one embodiment, when the aforementioned adjustment instruction information includes the first adjustment information, the aforementioned calibration space is adjusted by adjusting the clamping degree between the target radar and the metal plate. For details, please refer to the aforementioned... Figure 4 The illustrated scheme 2 is used for processing; when the aforementioned adjustment instruction information includes the second adjustment information, the aforementioned calibration space is adjusted by adjusting the placement of the calibration object, as detailed in the reference. Figure 6 The process is carried out according to scheme 3 shown.

[0135] As one embodiment, the aforementioned first adjustment information includes first indication information and / or second indication information. The aforementioned first indication information is an indication of whether to adjust the first relative position. Those skilled in the art can flexibly set the specific form of the first indication information according to actual needs. For example, it can be, but is not limited to, displaying the text "Please adjust the relative position of the metal plate and the target radar" on the display page as the first indication information. Alternatively, a calibration space stereoscopic diagram of the calibration space can be constructed in advance on the display page, and the enhanced display of the metal plate and the target radar in the calibration space stereoscopic diagram can be used as the first indication information. The aforementioned second indication information includes the horizontal angle θ and the pitch angle Φ between the first reference vector a and the second reference vector b. The meaning and determination method of the first reference vector a, the second reference vector b, the horizontal angle θ, and the pitch angle Φ are explained in the foregoing content and will not be repeated here.

[0136] As one embodiment, the aforementioned second adjustment information includes third and / or fourth indication information; the aforementioned third indication information includes an indication of whether to adjust the second relative position. Those skilled in the art can flexibly set the specific form of the second indication information according to actual needs. For example, it can be, but is not limited to, displaying the text "Please adjust the relative position of the calibration object and the metal plate" on the display page as the second indication information. Alternatively, a three-dimensional view of the calibration space can be constructed in advance on the display page, and the enhanced display of the calibration object in the three-dimensional view can be used as the second indication information. The aforementioned fourth indication information is the extension line of the third reference vector or the positional distribution of the third reference vector and the target radar, which can be, but is not limited to, the reference... Figure 7 The third reference vector is the inverse of the first reference vector a, and the aforementioned third reference vector passes through the center of the aforementioned calibration object, while the aforementioned first reference vector is a normal vector perpendicular to the aforementioned darkroom wall.

[0137] Please refer to Figure 9 Based on the same inventive concept, this application also provides an anechoic chamber radar calibration device 900 based on lidar point clouds. The anechoic chamber radar calibration device 900 includes a central control unit 910, a point cloud acquisition unit 920, a first calibration unit 930, and a second calibration unit 940.

[0138] The main control unit 910 is used to perform at least one round of radar calibration operation on the set calibration space until the radar calibration termination condition is met. The aforementioned calibration space is set up as follows: a turntable and a calibration object are set up in an anechoic chamber, and the target radar is fixed to the turntable using a metal plate, forming a fixed structure with the target radar, turntable, and metal plate; a lidar is set between the calibration object and the target radar; in each round of the aforementioned radar calibration operation:

[0139] The point cloud acquisition unit 920 is used to acquire, via lidar, a point cloud of the calibration object and a point cloud of at least one reference target, wherein the reference target point cloud is point cloud data acquired from one or more targets among the darkroom wall, target radar, and metal plate of the darkroom.

[0140] The first calibration unit 930 is used to calibrate the first relative position between the target radar and the turntable based on at least one reference target point cloud.

[0141] The second calibration unit 940 is used to calibrate the second relative position between the calibration object and the target radar, based at least on the calibration object point cloud.

[0142] Since the anechoic chamber radar calibration device 900 is the same as the one described in this application embodiment... Figure 3The illustrated device is an anechoic chamber radar calibration method based on lidar point clouds. The principle of this physical device in solving the problem is similar to that of the method. Therefore, the implementation of this anechoic chamber radar calibration device 900 can be referred to the implementation of the method. The repeated parts will not be described again.

[0143] Please refer to Figure 10 Based on the same inventive concept, this application also provides an anechoic chamber radar calibration device 1000 based on lidar point clouds. The anechoic chamber radar calibration device 1000 includes a central control unit 1010, a point cloud acquisition unit 1020, and an information display unit 1030.

[0144] The main control unit 1010 is used to perform at least one round of radar calibration operations on the established calibration space until the radar calibration termination conditions are met. The aforementioned calibration space is set up as follows: a turntable and a calibration object are set up in an anechoic chamber, and the target radar is fixed to the turntable by a metal plate, so that the target radar, the turntable, and the metal plate form a fixed body; and a lidar is set up between the calibration object and the target radar; each round of the aforementioned radar calibration operation includes:

[0145] The point cloud acquisition unit 1020 is used to acquire a point cloud of a calibration object and a point cloud of at least one reference target by a lidar, wherein the reference target point cloud is point cloud data acquired from one or more targets among the darkroom wall, target radar, and metal plate of the darkroom.

[0146] The information display unit 1030 is used to display adjustment instruction information of the aforementioned calibration space through a display terminal, so as to notify the aforementioned calibration space to be adjusted through the adjustment instruction information; wherein, the aforementioned adjustment instruction information is obtained by processing at least one of the aforementioned calibration object point cloud and the aforementioned reference target point cloud, and the aforementioned adjustment instruction information includes first adjustment information for a first relative position and / or second adjustment information for a second relative position, wherein the aforementioned first relative position is the relative position between the target radar and the turntable, and the aforementioned second relative position is the relative position between the calibration object and the target radar.

[0147] Since the anechoic chamber radar calibration device 1000 is the same as the one described in this application embodiment... Figure 8 The illustrated device is an anechoic chamber radar calibration method based on lidar point clouds. The principle of this physical device in solving the problem is similar to that of the method. Therefore, the implementation of this anechoic chamber radar calibration device 1000 can be referred to the implementation of the method. The repeated parts will not be described again.

[0148] Please see Figure 11Based on the same inventive concept, this application also provides an anechoic chamber radar calibration device 1100 based on laser point clouds, including a memory 1110 and a processor 1120. The memory 1110 stores computer instructions, and the processor 1120 executes the computer instructions to achieve the aforementioned... Figure 3 This illustrates any one of the anechoic chamber radar calibration methods based on lidar point clouds and / or Figure 8 Any of the illustrated anechoic chamber radar calibration methods based on lidar point clouds; since this device is the physical device of the anechoic chamber radar calibration device 900 and / or anechoic chamber radar calibration device 1000 in the embodiments of this application, that is, the physical device that performs the method provided in this application, and the principle of solving the problem by this physical device is similar to that of this method, the implementation of this physical device can refer to the implementation of the method, and the repeated parts will not be described again.

[0149] Based on the same inventive concept, this disclosure provides a computer storage medium, which includes computer program code. When the computer program code is run on a computer, it causes the computer to perform the actions described above. Figure 3 This illustrates any one of the anechoic chamber radar calibration methods based on lidar point clouds and / or Figure 8 The illustration shows any one of the anechoic chamber radar calibration methods based on lidar point clouds. Since the principle behind the problem solved by the aforementioned computer storage medium is similar to that of the anechoic chamber radar calibration method based on lidar point clouds, the implementation of the aforementioned computer storage medium can be found in the implementation of the method; repeated details will not be elaborated further.

[0150] In specific implementation, computer storage media can include: Universal Serial Bus Flash Drive (USB), portable hard drive, Read-Only Memory (ROM), Random Access Memory (RAM), magnetic disk or optical disk, and other storage media that can store program code.

[0151] Based on the same inventive concept, this disclosure also provides a computer program product, which includes: computer program code, which, when run on a computer, causes the computer to perform the aforementioned actions. Figure 3 This illustrates any one of the anechoic chamber radar calibration methods based on lidar point clouds and / or Figure 8 The illustration shows any one of the anechoic chamber radar calibration methods based on lidar point clouds. Because the problem-solving principle of the aforementioned computer program product is similar to that described earlier... Figure 3 and / or Figure 8The illustration shows that any of the anechoic chamber radar calibration methods based on lidar point clouds are similar. Therefore, the implementation of the above computer program product can be referred to the implementation of the method, and the repeated parts will not be described again.

[0152] Computer program products may employ any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0153] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0154] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for anechoic chamber radar calibration based on lidar point clouds, characterized in that, include: The calibration space is configured with at least one round of radar calibration operations until the radar calibration termination conditions are met. The calibration space is configured as follows: a turntable and a calibration object are placed in an anechoic chamber, and the target radar is fixed to the turntable using a metal plate, forming a fixed structure with the target radar, turntable, and metal plate. A lidar is placed between the calibration object and the target radar. Each round of the radar calibration operation includes steps S1 to S3. Step S1: Acquire a point cloud of the calibration object and a point cloud of at least one reference target using a lidar. The reference target point cloud is point cloud data collected from one or more targets among the darkroom walls, target radar, and metal plate of the darkroom. Step S2: Based on the at least one reference target point cloud, calibrate the first relative position between the target radar and the turntable; The at least one reference target point cloud includes a wall point cloud acquired for the walls of the darkroom and a radar point cloud acquired for the target radar. The calibration of the first relative position between the target radar and the turntable based on the at least one reference target point cloud includes: Based on the wall point cloud, a normal vector perpendicular to the wall of the darkroom is constructed as a first reference vector; and, at least based on the radar point cloud, a normal vector perpendicular to the radar plane of the target radar is constructed as a second reference vector. Based on the first reference vector and the second reference vector, it is determined whether the first relative position adjustment condition is met; the first relative position adjustment condition is that the horizontal angle and the pitch angle between the first reference vector and the second reference vector are both preset values; If it is determined that the first relative position adjustment condition is met, the clamping degree of the target radar and the metal plate is adjusted, and the process proceeds to step S3; if it is determined that the first relative position adjustment condition is not met, the process proceeds directly to step S3. Step S3, at least based on the calibration point cloud, calibrates the second relative position between the calibration object and the target radar, including: The center of the calibration object is determined based on the point cloud of the calibration object; The inverse vector of the first reference vector, drawn through the center of the calibration object, is the third reference vector; Determine whether the third reference vector satisfies the second relative position calibration condition; the second relative position calibration condition is that the extension line of the third reference vector or the third reference vector passes through the center point of the target radar; If the third reference vector satisfies the second relative position calibration condition, the placement of the calibrator is adjusted; if the third reference vector does not satisfy the second relative position calibration condition, the calibration of the second relative position is completed.

2. The method as described in claim 1, characterized in that, The target radar and the metal plate are secured together by multiple loosely fasteners at different locations; adjusting the clamping degree between the target radar and the metal plate includes: The first relative position of the target radar and the metal plate is adjusted by adjusting the tightness of the loose and fasteners at the off-center position of the target radar and the metal plate, wherein the off-center position is a position outside the center position of the metal plate.

3. The method as described in claim 1, characterized in that, The construction of a first reference vector based on the wall point cloud, perpendicular to the wall of the darkroom, includes: Perform singular value decomposition on the point cloud on the wall; Based on the singular value decomposition results, a normal vector perpendicular to the wall of the darkroom is constructed as the first reference vector.

4. The method as described in claim 1, characterized in that, The construction of a second reference vector, based at least on radar point clouds and perpendicular to the radar plane of the target radar, includes: A second reference vector is constructed based on the radar point cloud, with a normal vector perpendicular to the radar plane. The starting point and direction of the second reference vector are determined based on the radar point cloud; or The at least one reference target point cloud also includes a metal plate point cloud collected for the metal plate. Based on the radar point cloud and the metal plate point cloud, a normal vector perpendicular to the radar plane of the target radar is constructed as a second reference vector. The starting point of the second reference vector is determined based on the radar point cloud, and the direction of the second reference vector is determined based on the metal plate point cloud.

5. The method as described in claim 1, characterized in that, Before performing at least one round of radar calibration operations on the set calibration space until the radar calibration termination condition is met, the process also includes: Point cloud data of the turntable is collected using lidar. The rotation center of the turntable is determined by the turntable point cloud; The center position of the metal plate is fixed at the rotation center; and the radar is fixed to the metal plate through the non-center position of the metal plate.

6. The method as described in claim 1, characterized in that, After performing at least one round of radar calibration operations on the set calibration space until the radar calibration termination condition is met, the process also includes: Based on the point cloud of the calibration object and the point cloud of the radar, the distance between the center points of the calibration object and the target radar is determined; The calibration object is set at preset coordinates in the radar coordinate system corresponding to the target radar, where the preset coordinates are (spacing, 0, 0).

7. A method for anechoic chamber radar calibration based on lidar point clouds, characterized in that, Applications to automated calibration and analysis units include: The calibration space is configured with at least one round of radar calibration operations until the radar calibration termination conditions are met. The calibration space is configured as follows: a turntable and a calibration object are placed in an anechoic chamber, and the target radar is fixed to the turntable using a metal plate, forming a fixed structure with the target radar, turntable, and metal plate. A lidar is placed between the calibration object and the target radar. Each round of radar calibration operations includes: The point cloud of the calibration object and at least one reference target are acquired by the lidar, wherein the reference target point cloud is point cloud data acquired from one or more targets among the darkroom walls, target radar, and metal plate. The calibration space adjustment instruction information is displayed on the display terminal to notify the user to adjust the calibration space; wherein, The adjustment instruction information is obtained by processing at least one of the calibration point cloud and the reference target point cloud. The adjustment instruction information includes first adjustment information for a first relative position and / or second adjustment information for a second relative position. The first relative position is the relative position between the target radar and the turntable, and the second relative position is the relative position between the calibration object and the target radar. The at least one reference target point cloud includes a wall point cloud acquired against the walls of the anechoic chamber and a radar point cloud acquired against the target radar; the adjustment of the first relative position includes: Based on the wall point cloud, a normal vector perpendicular to the wall of the darkroom is constructed as a first reference vector; and, at least based on the radar point cloud, a normal vector perpendicular to the radar plane of the target radar is constructed as a second reference vector. Based on the first reference vector and the second reference vector, it is determined whether the first relative position adjustment condition is met; the first relative position adjustment condition is that the horizontal angle and the pitch angle between the first reference vector and the second reference vector are both preset values; If the first relative position adjustment condition is met, the clamping degree of the target radar and the metal plate is adjusted, and the second relative position adjustment is initiated; if the first relative position adjustment condition is not met, the second relative position adjustment is initiated directly. Adjustments to the second relative position include: The center of the calibration object is determined based on the point cloud of the calibration object; The inverse vector of the first reference vector, drawn through the center of the calibration object, is the third reference vector; Determine whether the third reference vector satisfies the second relative position calibration condition; the second relative position calibration condition is that the extension line of the third reference vector or the third reference vector passes through the center point of the target radar; If the third reference vector satisfies the second relative position calibration condition, the placement of the calibration object is adjusted; if the third reference vector does not satisfy the second relative position calibration condition, the adjustment of the second relative position is completed.

8. The method as described in claim 7, characterized in that, When the adjustment instruction information includes the first adjustment information, the calibration space is adjusted by adjusting the clamping degree between the target radar and the metal plate; When the adjustment instruction information includes the second adjustment information, the calibration space is adjusted by adjusting the placement of the calibration object.

9. The method as described in claim 7 or 8, characterized in that, The first adjustment information includes first indication information and / or second indication information. The first indication information is an indication of whether to adjust the first relative position; The second indication information includes the horizontal angle and the pitch angle between the first reference vector and the second reference vector; the first reference vector is a normal vector perpendicular to the wall of the darkroom, and the first reference vector is constructed based on the point cloud of the wall; the second reference vector is a normal vector perpendicular to the radar plane of the target radar, and the second reference vector is constructed based on the radar point cloud.

10. The method as described in claim 7 or 8, characterized in that, The second adjustment information includes third and / or fourth indication information; The third indication information includes an indication of whether to adjust the second relative position; The fourth indication information is the extension of the third reference vector or the positional distribution of the third reference vector and the target radar; the third reference vector is the inverse vector of the first reference vector, and the third reference vector passes through the center of the calibration object, and the first reference vector is the normal vector perpendicular to the wall of the darkroom.

11. An anechoic chamber radar calibration device based on lidar point clouds, characterized in that, It includes a memory and a processor, the memory being used to store computer instructions, and the processor being used to execute the computer instructions to implement the method as claimed in any one of claims 1-6 or 7-10.

12. A computer storage medium, characterized in that, The computer storage medium stores a computer program, the computer program including program instructions, which, when executed by the computer, cause the computer to perform the method as described in any one of claims 1-6 or 7-10.

Images