Laser radar calibration device and method

Abstract

The embodiments of this specification provide a laser radar calibration device and method. The device includes: a stage for carrying the laser radar to be calibrated; a camera array for obtaining a first light spot imaging of the laser beam emitted by the laser radar to be calibrated in the measurement space; wherein the camera array includes one or more cameras covering different fields of view of the measurement space respectively, and each camera is used to obtain an image in a corresponding field of view; a control module for determining the actual emission angle of the laser beam based on the pixel coordinates of the first light spot imaging in the image obtained by the corresponding camera, and the calibration relationship between the pixel coordinates of the scanning point of the measurement space and the emission angle.

Description

[0001] Priority declaration

[0002] This application claims priority to Chinese application No. 202110480748.6 filed on April 30, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the field of laser technology, and in particular to a laser radar calibration device and method. Background Art

[0004] LiDAR detects the environment and objects within the target range by emitting laser light to the target range or object and receiving the reflected light from the object, such as the position (e.g., distance and angle), motion state (e.g., speed, vibration, and posture), and shape. Since errors may exist in the design and manufacturing of mechanical parts, LiDAR itself may have certain errors. Errors in LiDAR may cause deviations in the object data or information obtained when detecting objects.

[0005] Therefore, it is desirable to provide a laser radar calibration device and method. Summary of the invention

[0006] One aspect of the present specification provides a laser radar calibration device. The device includes: a stage for carrying the laser radar to be calibrated; a camera array for obtaining a first spot image of a laser beam emitted by the laser radar to be calibrated in a measurement space; wherein the camera array includes one or more cameras covering different fields of view of the measurement space, each camera is used to obtain an image in a corresponding field of view; a control module is used to determine the actual emission angle of the laser beam based on the pixel coordinates of the first spot image in the image obtained by the corresponding camera, and the calibration relationship between the pixel coordinates of the scanning point of the measurement space and the emission angle.

[0007] In some embodiments, the stage includes a multi-degree-of-freedom rotating stage, and the calibration relationship is obtained in the following manner: placing a standard light source on the stage to replace the laser radar to be calibrated; controlling the rotation of the stage to obtain a second light spot imaging of the standard light source at different scanning points in the measurement space through the camera array, and recording the rotation angle of the stage corresponding to the different scanning points as the emission angle of the standard light source; using the correspondence between the pixel coordinates of the second light spot imaging at the different scanning points in the image obtained by the corresponding camera and the rotation angle of the stage as the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the emission angle.

[0008] In some embodiments, the rotation angle includes an azimuth angle and a pitch angle; when the standard light source is placed on the platform and the azimuth angle and the pitch angle of the platform are both 0, the azimuth angle and the pitch angle of the light beam of the standard light source are also 0; when the laser radar to be calibrated is placed on the platform, the azimuth angle and the pitch angle of the platform are both fixed at 0.

[0009] In some embodiments, in order to determine the actual emission angle of the laser beam based on the pixel coordinates of the first light spot imaging in the image obtained by the corresponding camera and the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the emission angle, the control module is also used to: determine the grid matrix where the first light spot imaging is located based on the pixel coordinates of the first light spot imaging in the image obtained by the corresponding camera, the minimum unit of the grid matrix is ​​composed of four adjacent scanning points; use at least three scanning points in the grid matrix as adjacent scanning points of the first light spot imaging; obtain the pixel coordinates and the corresponding emission angle of each adjacent scanning point from the calibration relationship; determine the actual emission angle of the laser beam based on the pixel coordinates of each adjacent scanning point, the emission angle and the pixel coordinates of the first light spot imaging in the image obtained by the corresponding camera.

[0010] In some embodiments, the device further includes an imaging screen for receiving the laser beam emitted by the standard light source or the laser radar to be calibrated to form a light spot, and the measurement space is formed on the imaging screen.

[0011] In some embodiments, the device further comprises a bracket for adjusting the position of the camera array or a single camera in the camera array.

[0012] Another aspect of the present specification provides a laser radar calibration method. The method includes: obtaining the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the exit angle; emitting a laser beam through the laser radar to be calibrated placed on the stage; obtaining the first light spot imaging of the laser beam emitted by the laser radar to be calibrated in the measurement space through a camera array; the camera array includes one or more cameras covering different fields of view of the measurement space respectively, and each camera is used to obtain an image in a corresponding field of view; based on the pixel coordinates of the first light spot imaging in the image obtained by the corresponding camera of the camera array, and the calibration relationship, determining the actual exit angle of the laser beam.

[0013] In some embodiments, the stage is a multi-degree-of-freedom rotating stage; the calibration relationship between the pixel coordinates and the output angle of the scanning point in the measurement space is obtained, including: placing a standard light source on the stage to replace the laser radar to be calibrated; controlling the rotation of the stage to obtain the second light spot imaging of the standard light source at different scanning points in the measurement space through the camera array, and recording the rotation angle of the stage corresponding to the different scanning points as the output angle of the standard light source; the correspondence between the pixel coordinates of the second light spot imaging at the different scanning points in the image obtained by the corresponding camera and the rotation angle of the stage is used as the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the output angle.

[0014] In some embodiments, the rotation angle of the platform includes an azimuth angle and a pitch angle; when the standard light source is placed on the platform and the azimuth angle and the pitch angle of the platform are both 0, the azimuth angle and the pitch angle of the light beam of the standard light source are also 0; when the laser radar to be calibrated is placed on the platform, the azimuth angle and the pitch angle of the platform are both fixed at 0.

[0015] In some embodiments, the actual emission angle of the laser beam is determined based on the pixel coordinates of the first light spot imaging in the image acquired by the corresponding camera and the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the emission angle, including: determining a grid matrix where the first light spot imaging is located based on the pixel coordinates of the first light spot imaging in the image acquired by the corresponding camera, wherein the minimum unit of the grid matrix is ​​composed of four scanning points adjacent to each other; taking at least three scanning points in the grid matrix as adjacent scanning points of the first light spot imaging; acquiring the pixel coordinates and the corresponding emission angle of each adjacent scanning point from the calibration relationship; and determining the actual emission angle of the laser beam based on the pixel coordinates of each adjacent scanning point, the emission angle and the pixel coordinates of the first light spot imaging in the image acquired by the corresponding camera.

[0016] In some embodiments, the pixel coordinates and the emission angle of the first adjacent scanning point are respectively (x 1 ,y 1 ), (θ x1 ,θ y1 ), the pixel coordinates and the emission angle of the second adjacent scanning point are (x 2 ,y 2 ), (θ x2 ,θ y2 ), the pixel coordinates and the emission angle of the third adjacent scanning point are (x 3 ,y 3 ), (θ x3 ,θ y3), the pixel coordinates of the first light spot imaged in the image obtained by the corresponding camera are (x, y), then the actual emission angle (θ x ,θ y )for:

[0017]

[0018] BRIEF DESCRIPTION OF THE DRAWINGS

[0019] This specification will be further described in the form of exemplary embodiments, which will be described in detail by the accompanying drawings. These embodiments are not restrictive, and in these embodiments, the same number represents the same structure, wherein:

[0020] Figure 1 is a schematic diagram of an exemplary laser radar calibration device according to some embodiments of the present specification;

[0021] Figure 2 is a schematic diagram of an exemplary camera array according to some embodiments of the present specification;

[0022] Figure 3 is a schematic diagram of an exemplary carrier according to some embodiments of the present specification;

[0023] Figure 4 is an exemplary flow chart of a laser radar calibration method according to some embodiments of this specification;

[0024] Figure 5 is a schematic diagram of an exemplary lidar calibration method according to some embodiments of the present specification. DETAILED DESCRIPTION

[0025] In order to more clearly illustrate the technical solutions of the embodiments of this specification, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of this specification. For ordinary technicians in this field, this specification can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0026] It should be understood that the "system", "device", "unit" and / or "module" used herein are a method for distinguishing different components, elements, parts, portions or assemblies at different levels. However, if other words can achieve the same purpose, the words can be replaced by other expressions.

[0027] As shown in this specification and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0028] Although this specification makes various references to certain modules or units in the system according to the embodiments of this specification, any number of different modules or units can be used and run on the client and / or server. The modules are illustrative only, and different aspects of the system and method can use different modules.

[0029] Flowcharts are used in this specification to illustrate the operations performed by the system according to the embodiments of this specification. It should be understood that the preceding or following operations are not necessarily performed precisely in order. Instead, the steps may be processed in reverse order or simultaneously. At the same time, other operations may also be added to these processes, or one or more operations may be removed from these processes.

[0030] Laser radar can detect the characteristics of the environment and objects within the target range by emitting lasers to the target range or object and receiving the reflected light of the object. Its detection accuracy reflects the level of accurate detection of the target range environment. For example, in an unmanned driving scenario, the laser radar can detect the position, speed and other characteristics of the environment and objects around the vehicle by emitting lasers to objects around the unmanned vehicle and receiving the reflected light of the object, thereby providing environmental information for the autonomous driving strategy. If the laser radar has a large detection error, it will not only affect the implementation of the vehicle's autonomous driving strategy, but will also be a major hidden danger to the vehicle's driving safety. By calibrating the laser radar, the actual emission angle of the laser radar under the set emission angle can be determined, thereby verifying whether the emission angle of the laser radar is accurate. Furthermore, the deviation between the set emission angle and the actual emission angle of the laser radar can be determined, and a corresponding relationship between the set emission angle and the actual emission angle can be established. Based on the corresponding relationship, the deviation is compensated to calibrate the laser radar's detection result of the object.

[0031] In some embodiments of the present specification, the laser radar calibration device can obtain an image of the spot imaging of the laser beam emitted by the laser radar to be calibrated through a camera, and determine the actual exit angle of the laser beam based on the pixel coordinates of the spot in the image. Considering that the camera's shooting field of view and edge imaging distortion are usually a pair of contradictions, if a wide-angle camera lens is used to cover a sufficient shooting field of view, the edge of the captured spot image may produce geometric distortion, affecting the calculation of the actual exit angle of the laser beam. The embodiments of the present specification provide a laser radar calibration device, which uses one or more cameras to divide the measurement space of the laser beam, and can obtain a higher resolution spot image, thereby improving the precision and accuracy of the laser radar calibration.

[0032] Figure 1 is a schematic diagram of an exemplary lidar calibration device according to some embodiments of the present specification.

[0033] like Figure 1 As shown, the laser radar calibration device 100 may include a carrier 110 , a camera array 120 , and an imaging screen 130 .

[0034] The carrier 110 can be used to carry the laser radar to be calibrated. The laser radar to be calibrated can be used to emit a laser beam. In some embodiments, the laser radar can emit laser beams with different azimuths and elevations, that is, it can emit laser beams with different deflection angles in the horizontal and vertical directions, respectively. For example, the laser radar can emit a laser beam of -60 degrees to +60 degrees in the vertical plane, or emit a laser beam of -45 degrees to 45 degrees in the horizontal plane. In some embodiments, the laser radar to be calibrated can be placed on the carrier 110 by a fixture. For example, the fixture can include a tray, a bracket, a liftable rail, and other devices that can adjust the position of the laser radar to be calibrated. In some embodiments, the laser radar to be calibrated may include but is not limited to pulse laser radar, continuous wave laser radar, etc.

[0035] In some embodiments, the stage 110 may include a multi-degree-of-freedom rotating stage. In some embodiments, the stage 110 may be used to carry a standard light source. Figure 3310) refers to a laser light source that can emit light at a known angle after being calibrated by an optical platform. In some embodiments, a standard light source can be used to calibrate the grid of the measurement space. For example, a standard light source can be placed on the stage 110 to replace the laser radar to be calibrated, and the stage 110 can be controlled to rotate a certain azimuth and pitch angle so that the light beam of the standard light source can hit a certain node (i.e., scanning point) of the predefined grid of the measurement space. The second light spot imaging of the standard light source at different scanning points in the measurement space is obtained through the camera array 120, and the pixel coordinates of the second light spot imaging in the image obtained by the corresponding camera are calculated. The quadrilateral with four adjacent groups of "emergence angle (i.e., azimuth and pitch angle)-pixel coordinates of the light spot imaging" information as vertices is defined as the smallest unit of a grid matrix, and a scanning grid is composed of several rows and columns of point grid matrices, thereby realizing the grid calibration of the measurement space.

[0036] The measurement space refers to the space that can cover the scanning range (Field of View, FOV) of the laser radar to be calibrated. The scanning range of the laser radar refers to the range of the emission angles of the laser beam that the laser radar can emit. For example, the laser radar can emit a laser beam of -60 degrees to +60 degrees in the vertical plane and a laser beam of -45 degrees to 45 degrees in the horizontal plane, and its corresponding scanning range is 90 degrees horizontally and 120 degrees vertically. In some embodiments, the measurement space can be formed on the imaging screen 130 to obtain the pixel coordinates of the spot formed by the laser beam on the imaging screen. In some embodiments, the size of the measurement space can be greater than, less than or equal to the area of ​​the imaging screen 130. In some embodiments, the size of the coverage area of ​​the measurement space is associated with the distance between the camera array 120 and the imaging screen 130. For example, the smaller the distance between the camera array 120 and the imaging screen 130, the smaller the coverage range of the corresponding measurement space. In some embodiments, the size of the coverage area of ​​the measurement space can be adjusted in real time according to the scanning range of the laser radar to be calibrated, and this specification does not limit this.

[0037] The predefined grid refers to a scanning grid predefined based on the parameters of the laser radar to be calibrated. Specifically, the standard light source can be fixed on the stage 110 so that the light beam emitted by the standard light source is relatively stationary with respect to the stage. For example, when the rotation angle (such as azimuth and pitch angle) of the stage 110 is 0, the emission angle of the light beam emitted by the standard light source is also 0. Among them, when the laser beam is parallel to the ground or the horizontal plane, the corresponding pitch angle is 0; when the laser beam has no offset relative to the median perpendicular plane that divides the measurement space into left and right parts, the corresponding azimuth angle is 0. In some embodiments, the geometric center of the imaging screen 130 can be used as the center origin of the measurement space, and then by adjusting the position of the standard light source relative to the stage 110, when the pitch angle and azimuth angle of the stage 110 are both 0 degrees, the light spot of the light beam emitted by the standard light source fixed thereon is located at the center origin. Afterwards, the stage 110 is moved in the pitch direction and the horizontal direction at a certain step. Every time the stage rotates in the pitch direction (vertical direction) and / or the horizontal direction by the step, the light beam emitted by the standard light source forms a light spot in the measurement space, thereby forming the predefined grid, and the position of each light spot can be regarded as a scanning point. In some embodiments, the grid size of the predefined grid can be determined based on the severity of the distortion of the camera lens. For example, when the distortion of the camera in the camera array 120 is large, a smaller grid can be used to determine the predefined grid of the measurement space, thereby reducing the impact of the camera distortion on the calibration accuracy. In some embodiments, the minimum grid unit of the predefined grid or the distance between adjacent scanning points can be determined based on the angular resolution of the laser radar to be calibrated.

[0038] In some embodiments, the angular difference between adjacent scanning points satisfies the angular resolution of the laser radar to be calibrated. For example, if the angular resolution of the laser radar is 0.1 degrees, the angular difference between the exit angles (e.g., azimuth or elevation) corresponding to adjacent scanning points of the predefined grid can be 1 degree. For example, based on the laser radar to be calibrated with an angular resolution of 0.1 degrees, the minimum unit grid of the predefined grid can be defined as a quadrilateral with four sets of "exit angle-pixel coordinates of spot imaging" information corresponding to four adjacent exit angles (azimuth 1 degree, elevation 0 degrees), (azimuth 2 degrees, elevation 0 degrees), (azimuth 2 degrees, elevation 1 degree), (azimuth 1 degree, elevation 1 degree) as vertices. The angular resolution of the laser radar refers to the angular resolution of the laser radar in the horizontal or vertical direction. In some embodiments, the angular resolution is also called the pointing accuracy of the laser radar, which can reflect the measurement accuracy of the laser radar. For example, if the laser radar pointing accuracy is 0.01 radians (converted to an angle of 0.6 degrees), a resolution of 1 meter can be obtained at a distance of 100 meters. If the laser radar pointing accuracy is 0.001 radians, a resolution of 1 meter can be obtained at a distance of 1000 meters.

[0039] In some embodiments, the rotation angles of the stage 110 corresponding to different scanning points can be recorded simultaneously as the emission angles of the standard light source, and the corresponding relationship between the pixel coordinates of the second light spot at different scanning points in the image obtained by the corresponding camera and the rotation angle of the stage 110 is used as the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the emission angle. In some embodiments, the rotation angle can include an azimuth angle and a pitch angle. The azimuth angle corresponds to the emission angle in the horizontal direction, and the pitch angle corresponds to the emission angle in the vertical direction.

[0040] In some embodiments, the stage 110 is in a fixed state when carrying the laser radar to be calibrated, and the azimuth and elevation angles are both 0. It can be understood that the laser radar to be calibrated does not need to rely on the stage to change the emission angle of the laser beam. Therefore, when the laser radar to be calibrated is placed on the stage 110, the stage 110 does not need to be rotated. In some embodiments, the standard light source or the laser radar to be calibrated can be placed on the stage 110 by a fixture, and then the position or height of the fixture can be adjusted so that the laser beam emitted by the laser radar to be calibrated when the set angle is (0,0) coincides with the beam of the standard light source when the emission angle is (0,0).

[0041] The camera array 120 can be used to obtain the spot imaging of the laser beam. For example, the camera array 120 can be used to obtain the first spot imaging of the laser beam emitted by the laser radar to be calibrated in the measurement space. For another example, the camera array 120 can be used to obtain the second spot imaging of the standard light source at different scanning points in the measurement space. In some embodiments, the camera array 120 may include one or more cameras that respectively cover different fields of view of the measurement space, for example, camera 121, camera 122, etc. Among them, each camera is used to obtain an image in a corresponding field of view. In some embodiments, the field of view of the camera array 120 can cover the entire measurement space. By dividing the measurement space by one or more cameras that respectively cover different fields of view of the measurement space, and integrating multiple cameras so that the camera array covers the entire spatial measurement range, a spot image of the laser beam with higher definition can be obtained. Based on the spot image, a more accurate spot position can be obtained, thereby improving the calibration accuracy of the laser radar calibration device.

[0042] In some embodiments, the camera array 120 may include, but is not limited to, optical cameras, industrial cameras, and the like. In some embodiments, the camera array 120 may include cameras and a platform (e.g., platform 210) that carries the cameras. In some embodiments, the number of cameras and / or the camera layout in the camera array 120 may be determined based on a combination of one or more parameters such as the scanning range of the laser radar to be calibrated, the distance between the camera array and the imaging screen, or the field of view of a single camera. For example, for a laser radar to be calibrated with a resolution of 0.1 degrees, the camera array 120 may include two 12-megapixel cameras placed side by side horizontally. In some embodiments, the higher the pixel of the camera, the fewer the number of cameras in the corresponding camera array. In some embodiments, the resolution of the camera may be one-third, one-half, and the like of the resolution of the laser radar to be calibrated.

[0043] The imaging screen 130 can be used to receive the laser beam emitted by the laser radar to be calibrated and / or the standard light source. When the emitted laser beam reaches the imaging screen 130, a light spot can be formed on the imaging screen 130. In some embodiments, the plane position of the imaging screen 130 can be calibrated when the imaging screen 130 is installed to ensure that the plane of the imaging screen 130 is vertical relative to the ground. In some embodiments, the imaging screen 130 can be fixedly mounted on the bracket of the laser radar calibration device 100. In some embodiments, the stage 110 can be located on the mid-vertical line of the imaging screen 130. In some embodiments, the distance between the stage 110 and the imaging screen 130 is directly proportional to the scanning range of the laser radar to be calibrated. The larger the scanning range of the laser radar to be calibrated, the larger the distance value between the stage 110 and the imaging screen 130.

[0044] In some embodiments, the stage 110 may be located between the camera array 120 and the imaging screen 130. In some embodiments, the distance between the camera array 120 and the stage 110 is less than the distance between the stage 110 and the imaging screen 130. In some embodiments, the camera array 120 may be located between the stage 110 and the imaging screen 130. In some embodiments, the distance between the camera array 120 and the stage 110 is less than the distance between the camera array 120 and the imaging screen 130. In some embodiments, the stage 110, the camera array 120, and the imaging screen 130 may be placed in any layout that enables the field of view of the camera array 120 to cover the imaging screen 130, and this specification does not limit this.

[0045] In some embodiments, the laser radar calibration device 100 may further include a control module (not shown in the figure). The control module may be used to control and / or schedule various modules in the laser radar calibration device 100 (e.g., the stage 110, the camera array 120, the imaging screen 130 or the bracket 140, etc.). In some embodiments, the control module may control the stage 110 to rotate to obtain the second spot imaging of the standard light source at different scanning points in the measurement space. In some embodiments, the control module may control at least one camera in the camera array 120 to obtain the spot imaging of the laser beam in the measurement space. For example, the control module may control the camera in the camera array 120 whose field of view corresponds to the set exit angle of the laser beam emitted by the laser radar to be calibrated to obtain the first spot imaging of the laser beam. For another example, the control module may control the camera in the camera array 120 whose field of view corresponds to the rotation angle of the stage 110 to obtain the second spot imaging of the standard light source in the measurement space. In some embodiments, the control module may determine the actual exit angle of the laser beam emitted by the laser radar to be calibrated. For example, the control module can determine the actual emission angle of the laser beam based on the pixel coordinates of the first light spot imaging in the image obtained by the corresponding camera, and the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the emission angle. Specifically, the control module can determine the grid matrix where the first light spot imaging is located based on the pixel coordinates of the first light spot imaging in the image obtained by the corresponding camera, and use at least three scanning points in the grid matrix as adjacent scanning points of the first light spot imaging; obtain the pixel coordinates and corresponding emission angle of each adjacent scanning point from the calibration relationship, and determine the actual emission angle of the laser beam based on the pixel coordinates of each adjacent scanning point, the emission angle, and the pixel coordinates of the first light spot imaging in the image obtained by the corresponding camera. For more information on determining the actual emission angle, please refer to other parts of this specification (for example, Figure 4 , Figure 5 In some embodiments, the control module may include but is not limited to a programmable chip, a desktop computer, a notebook computer, a mobile phone terminal, an iPad mobile terminal, etc.

[0046] In some embodiments, the laser radar calibration device 100 may further include a bracket 140. The bracket 140 may be used to provide arrangement and stable support for various components in the laser radar calibration device 100 (e.g., the stage 110, the camera array 120, or the imaging screen 130, etc.). For example, the bracket 140 may be used to adjust the horizontal distance between the stage 110 and the imaging screen 130. For another example, the bracket 140 may adjust the position of the camera array 120, or the position of a single camera in the camera array 120. It is understood that Figure 1 The arrow pointing to the bracket 140 is only for example, and the devices supporting the components such as the carrier 110, the camera array 120 and the imaging screen 130 in the laser radar calibration device 100 can all serve as part of the bracket 140.

[0047] In a specific embodiment, after determining the predefined grid of the measurement space based on the angular resolution of the laser radar to be calibrated, a standard light source can be placed on the stage 110 and turned on to emit light. Then, the stage 110 is controlled to the azimuth and pitch angles (i.e., the emission angle) corresponding to a certain node (i.e., the scanning point) of the predefined grid. At the same time, the corresponding cameras in the camera array 120 are controlled to obtain the second light spot imaging of the standard light source in the measurement space, and the pixel coordinates of the second light spot imaging in the image obtained by the corresponding camera are calculated. The stage 110 is controlled to traverse all predefined grid nodes, and the calibration relationship between the emission angle and the pixel coordinates corresponding to each node is stored. Furthermore, the azimuth and elevation angles of the stage 110 are returned to 0, the laser radar to be calibrated is placed on the stage 110 to replace the standard light source, and the position of the laser radar to be calibrated is adjusted so that the laser beam emitted by it with an azimuth and elevation angle of 0 coincides with the beam emitted by the standard light source with an exit angle of (0, 0); then the laser radar to be calibrated is controlled to emit a laser beam, and the first spot image of the laser beam is acquired through the corresponding camera in the camera array 120, and the actual exit angle of the laser beam is determined based on the pixel coordinates of the first spot image in the image acquired by the corresponding camera, and the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the exit angle. In some embodiments, the relative error angle of the laser beam can be obtained based on the actual exit angle of the laser beam and the set exit angle when the laser radar to be calibrated emits the laser beam.

[0048] Figure 2 is a schematic diagram of an exemplary camera array according to some embodiments of the present specification.

[0049] In some embodiments, the number of cameras in the camera array 120 can be determined based on the scanning range of the laser radar to be calibrated and the field of view of a single camera. For example, the angular resolution required by the laser radar to be calibrated can be analyzed to calculate the field of view that a single camera can cover, and then the number of cameras required can be calculated based on the scanning range of the laser radar to be calibrated.

[0050] For ease of understanding, Figure 2In the description, a camera array consisting of two cameras is taken as an example. In some embodiments, the camera 121 and the camera 122 can be placed horizontally side by side on the platform 210, and the field of view of the camera 121 and the camera 122 divides the measurement space evenly from left to right. For example, the field of view of the camera 121 and the camera 122 can cover the right area and the left area of ​​the center dotted line of the imaging screen 130 respectively. The camera 121 can be used to shoot the spot imaging (for example, the first spot imaging, the second spot imaging) formed by the laser beam emitted by the laser radar to be calibrated or the standard light source in the right area of ​​the imaging screen 130 (i.e., the right area of ​​the measurement space), and the camera 122 can be used to shoot the spot imaging formed by the laser beam emitted by the laser radar to be calibrated or the standard light source in the left area of ​​the imaging screen 130 (i.e., the left area of ​​the measurement space). In some alternative embodiments, the camera 121 and the camera 122 can be placed vertically in the same row, and the field of view divides the measurement space evenly from top to bottom. In some embodiments, the camera 121 and the camera 122 can cover different sizes of areas of the measurement space respectively, and the camera 121 and the camera 122 cover the entire measurement space together.

[0051] In some alternative embodiments, the camera array may include one or more sets of platforms 210. For example, when the camera array 120 includes four cameras, it may include two sets of stacked platforms 210, with two cameras placed horizontally side by side on each layer, and the field of view of each camera covers one quarter of the measurement space. In some embodiments, the camera may be fixedly or slidably mounted on the platform 210. In some embodiments, the performance parameters of each camera in the camera array may be the same or different.

[0052] It should be noted that the above description of the camera array 200 is only for example and explanation, and does not limit the scope of application of the present application. For those skilled in the art, various modifications and changes can be made to the camera array 200 under the guidance of the present application. However, these modifications and changes are still within the scope of the present application.

[0053] Figure 3 is a schematic diagram of an exemplary carrier according to some embodiments of the present specification.

[0054] like Figure 3As shown, in some embodiments, the stage 300 may include a multi-degree-of-freedom rotating stage, which may include an azimuth control module 113 and a pitch angle control module 115. The azimuth control module 113 can control the rotation of the stage in the horizontal direction, and the pitch angle control module 115 can control the rotation of the stage in the vertical direction. For example, the azimuth control module 113 can control the standard light source on the stage to achieve a 360-degree rotation in the horizontal direction, and the pitch angle control module 115 can control the standard light source on the stage to achieve a 180-degree rotation in the vertical direction. By superimposing the azimuth control module 113 and the pitch angle control module 115, precise control of the azimuth and pitch angle of the light source can be achieved. In some embodiments, the motion control accuracy and repeated positioning accuracy of the stage 300 can reach one thousandth.

[0055] It should be noted that the above description of the carrier 300 is only for illustration and description, and does not limit the scope of application of the present application. For those skilled in the art, various modifications and changes can be made to the carrier 300 under the guidance of the present application. However, these modifications and changes are still within the scope of the present application.

[0056] Figure 4 is an exemplary flow chart of a lidar calibration method according to some embodiments of the present specification.

[0057] Step 410, obtaining the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the exit angle.

[0058] The measurement space refers to a space that can cover the scanning range of the laser radar to be calibrated. The calibration relationship can reflect the correlation between the emission angle of the laser beam and the pixel coordinates of the laser beam spot imaging in the image. In some embodiments, the calibration relationship between the pixel coordinates of the scanning point and the emission angle can be obtained through the standard light source and the camera array. As an example only, the standard light source can be placed on the stage 110 to replace the laser radar to be calibrated, and the stage 110 is controlled to rotate to obtain the second spot imaging of the standard light source at different scanning points in the measurement space through the camera array 120, and the rotation angle of the stage 110 corresponding to the different scanning points is recorded as the emission angle of the standard light source, and the pixel coordinates of the second spot imaging at different scanning points in the image obtained by the corresponding camera and the corresponding relationship of the rotation angle of the stage 110 are used as the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the emission angle. Among them, the angle difference between the emission angles corresponding to adjacent scanning points meets the angular resolution of the laser radar to be calibrated, and four adjacent scanning points can form the minimum unit of a grid matrix, and several rows and columns of dot grid matrices can form a scanning grid. In some embodiments, the pixel coordinates of the scanning point refer to the pixel coordinates of the second light spot at the scanning point imaged in the coordinates of the image acquired by the corresponding camera, which can be obtained by any feasible method, for example, OpenCv, MATLAB and other tools, and this specification does not limit this.

[0059] The scanning point refers to a node of a predefined grid of the measurement space. In some embodiments, the minimum grid unit of the predefined grid can be determined based on the angular resolution of the laser radar to be calibrated. In some embodiments, the calibration relationship between the pixel coordinates of the scanning point of the measurement space and the exit angle can be stored in a storage device. In some embodiments, in response to detecting that there is uncollected "exit angle-pixel coordinates of spot imaging" data of a predefined grid node, the stage 110 can be controlled to rotate to the azimuth and pitch angle corresponding to the node, and the corresponding azimuth and pitch angles and the pixel coordinates of the second spot imaging can be recorded.

[0060] In some embodiments, the camera array may include one or more cameras that cover different fields of view of the measurement space, each camera being used to acquire an image within a corresponding field of view. In some embodiments, the system may control the camera array to acquire a second light spot imaging based on a shooting instruction. For example, after the control module controls the stage 110 to rotate to the azimuth and pitch angles corresponding to the scanning point, the camera array 120 may be controlled based on the shooting instruction to acquire a second light spot imaging of the standard light source at the scanning point with the field of view corresponding to the azimuth and pitch angles of the scanning point. In some embodiments, the pixel coordinate systems corresponding to the light spot imaging acquired by the same camera in the camera array are the same. In some embodiments, the pixel coordinate systems corresponding to the light spot imaging acquired by different cameras in the camera array may be the same or different.

[0061] In some embodiments, the rotation angle of the stage may include an azimuth angle and a pitch angle. In some embodiments, when the azimuth angle and the pitch angle of the stage are both 0, the azimuth angle and the pitch angle of the laser beam of the standard light source placed on the stage are also 0. In some embodiments, the pixel coordinates of the spot imaging of the light beam emitted by the standard light source when the azimuth angle and the pitch angle of the stage are both 0 can be defined as the center origin of the measurement space.

[0062] Step 420, emitting a laser beam through the laser radar to be calibrated placed on the stage.

[0063] In some embodiments, when the laser radar to be calibrated is placed on the stage, the azimuth and elevation angles of the stage are both 0. In some embodiments, the fixture of the laser radar to be calibrated can be adjusted so that the pixel coordinates of the spot imaging of the laser beam with an azimuth and elevation angle of 0 emitted by the laser radar to be calibrated placed on the stage are the same as the pixel coordinates of the spot imaging of the laser beam with an azimuth and elevation angle of 0 emitted when the standard light source is placed on the stage. In some embodiments, the fixture of the laser radar to be calibrated can be adjusted so that the spot imaging of the laser beam with an exit angle of (0,0) emitted by the laser radar to be calibrated placed on the stage is at the center origin of the measurement space. In some embodiments, the laser radar to be calibrated placed on the stage can emit laser beams with different set exit angles to achieve calibration of the laser beams with different set exit angles of the laser radar to be calibrated.

[0064] Step 430: acquiring, through a camera array, a first spot imaging of the laser beam emitted by the laser radar to be calibrated in the measurement space.

[0065] In some embodiments, the corresponding cameras in the camera array can be controlled to obtain the first light spot imaging of the laser beam in the measurement space based on the set emission angle of the laser beam emitted by the laser radar to be calibrated. For example, if the set emission angle of the laser beam emitted by the laser radar to be calibrated is in the left area of ​​the measurement space, the camera in the camera array whose field of view covers the left area of ​​the measurement space can be controlled to obtain the first light spot imaging formed by the laser beam on the imaging screen.

[0066] Step 440 , determining the actual emission angle of the laser beam based on the pixel coordinates of the first light spot imaged in the image acquired by the corresponding camera of the camera array and the calibration relationship.

[0067] In some embodiments, the pixel coordinates of the first light spot imaging can be obtained in any feasible way, for example, tools such as OpenCv and MATLAB, and this specification does not limit this. In some embodiments, the actual emission angle of the laser beam can be determined based on the pixel coordinates of at least two adjacent scanning points of the first light spot imaging, the emission angle, and the pixel coordinates of the first light spot imaging in the image obtained by the corresponding camera. In some embodiments, the grid matrix where the first light spot imaging is located can be determined based on the pixel coordinates of the first light spot imaging in the image obtained by the corresponding camera, and at least three scanning points in the grid matrix are used as adjacent scanning points of the first light spot imaging. In some embodiments, the grid matrix where the first light spot imaging is located can be determined based on the camera that obtains the image of the first light spot imaging. For example, Figure 5 As shown in , if the image of the first light spot imaging is obtained by taking a picture of the camera 122, then the scanning grid on the left side of the dotted line determined based on the scanning point information corresponding to the second light spot imaging taken by the camera 122 is the first light spot imaging (i.e. Figure 5 In some embodiments, the pixel coordinates of each adjacent scanning point and the corresponding exit angle can be obtained from the calibration relationship, and the actual exit angle of the laser beam can be determined based on the pixel coordinates of each adjacent scanning point, the exit angle, and the pixel coordinates of the first light spot imaged in the image obtained by the corresponding camera. For more information on determining the actual exit angle of the laser beam, please refer to other parts of this specification (for example, Figure 5 and its related description), which will not be repeated here.

[0068] It should be noted that the above description of method 400 is only for example and illustration, and does not limit the scope of application of this specification. For those skilled in the art, various modifications and changes can be made to method 400 under the guidance of this specification. However, these modifications and changes are still within the scope of this specification.

[0069] Figure 5 is a schematic diagram of an exemplary lidar calibration method according to some embodiments of the present specification.

[0070] For ease of understanding, the following will be combined Figure 5 The laser radar calibration process is described with a specific embodiment.

[0071] In some embodiments, the geometric center of the imaging screen 130 can be used as the central origin of the measurement space, and then by adjusting the position of the standard light source relative to the stage 110, when the pitch angle and azimuth angle of the stage 110 are both 0 degrees, the light spot of the light beam emitted by the standard light source fixed thereon is located at the central origin. In a specific embodiment, the azimuth angle control module 113 and the pitch angle control module 115 of the stage 110 can be adjusted to control the azimuth angle and pitch angle corresponding to the predefined grid node (i.e., the scanning point) of the measurement space from the standard light source, and based on the regional range of the azimuth angle and pitch angle in the measurement space, the camera in the camera array 120 whose field of view corresponds to the regional range is controlled to obtain the second light spot imaging of the standard light source at the scanning point in the measurement space. In some embodiments, the calibration relationship between the pixel coordinates of the scanning point and the emission angle can be determined based on the azimuth angle and pitch angle of the stage at the scanning point, and the pixel coordinates of the second light spot imaging of the scanning point in the image obtained by the corresponding camera. In some embodiments, four adjacent scanning points in the measurement space may be formed into a grid matrix, and several rows and columns of point grid matrices may form a scanning grid to achieve grid calibration of the measurement space.

[0072] In some embodiments, after completing the grid calibration of the measurement space, the azimuth and elevation angles of the stage 110 can be adjusted to 0, and the laser radar to be calibrated can be placed on the stage 110 to replace the standard light source. In some embodiments, the fixture of the laser radar to be calibrated can be adjusted so that the pixel coordinates of the spot imaging of the laser beam with an exit angle of (0,0) of the laser radar to be calibrated are at the center origin of the measurement space. In some embodiments, the laser radar to be calibrated can be controlled to emit laser beams with different set exit angles, and the corresponding cameras in the camera array 120 can be controlled to obtain the first spot imaging of the laser beam. In some embodiments, the grid matrix where the first spot imaging is located can be determined based on the pixel coordinates (x, y) of the first spot imaging in the image obtained by the corresponding camera. For example, the grid matrix where the first spot image is located can be determined based on the pixel coordinates of the first spot imaging in the image obtained by the corresponding camera, and the pixel coordinates of the scanning point corresponding to the second spot image taken by the camera.

[0073] In some embodiments, Figure 5 As shown in the circular dotted area, the distance d between the first light spot imaging (i.e., the light spot to be measured) and each adjacent scanning point in the grid matrix where it is located can be calculated based on the distance d between the first light spot imaging (i.e., the light spot to be measured) and each adjacent scanning point in the grid matrix where it is located. 1 d 2 d 3 and d 4 , determine the three scanning points with smaller distance values ​​as the three adjacent scanning points of the first light spot imaging. In some embodiments, the pixel coordinates of the first adjacent scanning point and the emission angle (x 1 ,y 1 ), (θx1 ,θ y1 ), the pixel coordinates of the second adjacent scanning point and the exit angle (x 2 ,y 2 ), (θ x2 ,θ y2 ), the pixel coordinates of the third adjacent scanning point and the exit angle (x 3 ,y 3 ), (θ x3 ,θ y3 ), the actual emission angle (θ) of the laser beam is calculated by formulas (1) and (2) x ,θ y ).

[0074]

[0075]

[0076] Among them, θ x Corresponding azimuth, θ y Corresponding pitch angle.

[0077] In some embodiments, the laser beam can be calibrated based on the set horizontal emission angle (i.e., the set azimuth angle) and the set vertical emission angle (i.e., the set pitch angle) of the laser beam in the laser radar to be calibrated, respectively. x and θ y The difference is calculated to obtain the error angle of the laser beam in the horizontal direction and the vertical direction respectively. In some embodiments, the laser beam emitted by the laser radar to be calibrated can be adjusted based on the error angle of the laser beam. In some embodiments, the error angle table or curve of the laser radar to be calibrated (reflecting the mapping relationship between different set emission angles and actual emission angles) can be obtained by calibrating the laser beams with different set emission angles to adjust the laser beam emitted by the laser radar to be calibrated.

[0078] It should be noted that the above description of method 500 is only for example and illustration, and does not limit the scope of application of the present application. For those skilled in the art, various modifications and changes can be made to method 500 under the guidance of the present application. However, these modifications and changes are still within the scope of the present application.

[0079] The beneficial effects that may be brought about by the embodiments of this specification include but are not limited to: (1) the measurement space is divided by a camera array composed of multiple cameras that cover different fields of view of the measurement space, so that the field of view of the camera array can cover the entire measurement space, and a spot image of the laser beam with higher resolution can be obtained; (2) based on the pixel coordinates and the emission angle of at least three scanning points of the scanning grid of the measurement space, the actual emission angle of the laser beam of the laser radar to be calibrated is determined. When the distance between the selected scanning points is small (such as the scanning points in the smallest grid where the first spot imaging falls), the error caused by the lens distortion at the edge of the camera imaging can be overcome, thereby improving the accuracy of the laser radar calibration device. It should be noted that different embodiments may have different beneficial effects. In different embodiments, the beneficial effects that may be produced may be any one or a combination of the above, or any other possible beneficial effects.

[0080] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of this specification. Although not explicitly stated here, those skilled in the art may make various modifications, improvements and corrections to this specification. Such modifications, improvements and corrections are suggested in this specification, so such modifications, improvements and corrections still belong to the spirit and scope of the exemplary embodiments of this specification.

[0081] At the same time, this specification uses specific words to describe the embodiments of this specification. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of this specification. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures or characteristics in one or more embodiments of this specification can be appropriately combined.

[0082] In addition, it will be understood by those skilled in the art that various aspects of this specification may be illustrated and described by a number of patentable categories or situations, including any new and useful process, machine, product or combination of substances, or any new and useful improvements thereto. Accordingly, various aspects of this specification may be performed entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The above hardware or software may be referred to as "data blocks", "modules", "engines", "units", "components" or "systems". In addition, various aspects of this specification may be represented as a computer product located in one or more computer-readable media, which includes computer-readable program code.

[0083] A computer storage medium may include a propagated data signal containing computer program code, for example, in baseband or as part of a carrier wave. The propagated signal may be in a variety of forms, including electromagnetic, optical, etc., or a suitable combination. A computer storage medium may be any computer-readable medium other than a computer-readable storage medium, which can be connected to an instruction execution system, device or apparatus to communicate, propagate or transmit the program for use. The program code on the computer storage medium may be transmitted via any suitable medium, including radio, cable, fiber optic cable, RF, or similar media, or any combination of the above media.

[0084] The computer program code required for the operation of each part of this specification can be written in any one or more programming languages, including object-oriented programming languages ​​such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python, etc., conventional procedural programming languages ​​such as C language, VisualBasic, Fortran2003, Perl, COBOL2002, PHP, ABAP, dynamic programming languages ​​such as Python, Ruby and Groovy, or other programming languages, etc. The program code can be run entirely on the user's computer, or run on the user's computer as an independent software package, or run partially on the user's computer and partially on a remote computer, or run entirely on a remote computer or processing device. In the latter case, the remote computer can be connected to the user's computer through any network form, such as a local area network (LAN) or a wide area network (WAN), or connected to an external computer (e.g., via the Internet), or in a cloud computing environment, or used as a service such as software as a service (SaaS).

[0085] In addition, unless explicitly stated in the claims, the order of the processing elements and sequences described in this specification, the use of alphanumeric characters, or the use of other names are not intended to limit the order of the processes and methods of this specification. Although the above disclosure discusses some invention embodiments that are currently considered useful through various examples, it should be understood that such details are only for illustrative purposes, and the attached claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the essence and scope of the embodiments of this specification. For example, although the system components described above can be implemented by hardware devices, they can also be implemented only by software solutions, such as installing the described system on an existing processing device or mobile device.

[0086] Similarly, it should be noted that in order to simplify the description disclosed in this specification and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this specification, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the subject matter of this specification are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0087] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of this specification are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0088] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, etc., cited in this specification are hereby incorporated by reference in their entirety. Except for application history documents that are inconsistent with or conflicting with the contents of this specification, documents that limit the broadest scope of the claims of this specification (currently or later attached to this specification) are also excluded. It should be noted that if the descriptions, definitions, and / or use of terms in the materials attached to this specification are inconsistent or conflicting with the contents described in this specification, the descriptions, definitions, and / or use of terms in this specification shall prevail.

[0089] Finally, it should be understood that the embodiments described in this specification are only used to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, as an example and not a limitation, alternative configurations of the embodiments of this specification may be considered consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly introduced and described in this specification.

Claims

1. A laser radar calibration device, the device comprising: A carrier, used for carrying the laser radar to be calibrated; A camera array, used to obtain a first spot image of the laser beam emitted by the laser radar to be calibrated in the measurement space; wherein the camera array includes one or more cameras respectively covering different fields of view of the measurement space, and each camera is used to obtain an image in a corresponding field of view; A control module, for determining the actual emission angle of the laser beam based on the pixel coordinates of the first light spot imaged in the image acquired by the corresponding camera and the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the emission angle, comprising: Determine a grid matrix where the first light spot is imaged based on pixel coordinates of the first light spot imaged in an image obtained by a corresponding camera, wherein the grid matrix is ​​a matrix obtained by grid calibration of the measurement space; The actual emission angle of the laser beam is determined based on the pixel coordinates of at least three scanning points in the grid matrix, the emission angle, and the pixel coordinates of the first light spot imaged in the image obtained by the corresponding camera.

2. The device according to claim 1, wherein the stage comprises a multi-degree-of-freedom rotating stage, and the calibration relationship is obtained by: Placing a standard light source on the stage to replace the laser radar to be calibrated; Controlling the rotation of the stage to obtain second light spot imaging of the standard light source at different scanning points in the measurement space through the camera array, and recording the rotation angles of the stage corresponding to the different scanning points as the emission angles of the standard light source; The correspondence between the pixel coordinates of the second light spots at the different scanning points imaged in the images obtained by the corresponding cameras and the rotation angle of the stage is used as the calibration relationship between the pixel coordinates of the scanning points in the measurement space and the emission angle.

3. The device according to claim 2, wherein the rotation angle comprises an azimuth angle and an elevation angle; When the standard light source is placed on the stage, and the azimuth angle and the pitch angle of the stage are both 0, the azimuth angle and the pitch angle of the light beam of the standard light source are also 0; When the laser radar to be calibrated is placed on the platform, the azimuth angle and pitch angle of the platform are both fixed to 0.

4. The device according to claim 2, in order to determine the actual emission angle of the laser beam based on the pixel coordinates of the first light spot imaged in the image acquired by the corresponding camera and the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the emission angle, the control module is further used to: At least three scanning points in the grid matrix are used as adjacent scanning points for imaging the first light spot, wherein the minimum unit of the grid matrix is ​​composed of four scanning points adjacent to each other; Obtaining pixel coordinates of each adjacent scanning point and a corresponding emission angle from the calibration relationship; The actual emission angle of the laser beam is determined based on the pixel coordinates of each adjacent scanning point, the emission angle, and the pixel coordinates of the first light spot imaged in the image obtained by the corresponding camera.

5. The device according to claim 1 further comprises an imaging screen for receiving a standard light source or a laser beam emitted by the laser radar to be calibrated to form a light spot, and the measurement space is formed on the imaging screen.

6. A laser radar calibration method, the method comprising: Obtaining the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the emission angle; The laser beam is emitted by the laser radar to be calibrated placed on the stage; Acquire a first light spot imaging of the laser beam emitted by the laser radar to be calibrated in the measurement space through a camera array; the camera array comprises one or more cameras covering different fields of view of the measurement space respectively, and each camera is used to acquire an image in a corresponding field of view; Determining the actual emission angle of the laser beam based on the pixel coordinates of the first light spot imaged in the image acquired by the corresponding camera of the camera array and the calibration relationship, comprising: Determine a grid matrix where the first light spot is imaged based on pixel coordinates of the first light spot imaged in an image obtained by a corresponding camera, wherein the grid matrix is ​​a matrix obtained by grid calibration of the measurement space; The actual emission angle of the laser beam is determined based on the pixel coordinates of at least three scanning points in the grid matrix, the emission angle, and the pixel coordinates of the first light spot imaged in the image obtained by the corresponding camera.

7. The method according to claim 6, wherein the stage is a multi-degree-of-freedom rotating stage; The step of obtaining the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the emission angle includes: Placing a standard light source on the stage to replace the laser radar to be calibrated; Controlling the rotation of the stage to obtain second light spot imaging of the standard light source at different scanning points in the measurement space through the camera array, and recording the rotation angles of the stage corresponding to the different scanning points as the emission angles of the standard light source; The correspondence between the pixel coordinates of the second light spots at the different scanning points imaged in the images obtained by the corresponding cameras and the rotation angle of the stage is used as the calibration relationship between the pixel coordinates of the scanning points in the measurement space and the emission angle.

8. The method according to claim 7, wherein the rotation angle of the stage comprises an azimuth angle and a pitch angle; When the standard light source is placed on the stage, and the azimuth angle and the pitch angle of the stage are both 0, the azimuth angle and the pitch angle of the light beam of the standard light source are also 0; When the laser radar to be calibrated is placed on the platform, the azimuth angle and pitch angle of the platform are both fixed to 0.

9. The method according to claim 6, wherein determining the actual emission angle of the laser beam based on the pixel coordinates of the first light spot imaged in the image acquired by the corresponding camera and the calibration relationship between the pixel coordinates of the scanning point in the measurement space and the emission angle comprises: At least three scanning points in the grid matrix are used as adjacent scanning points for imaging the first light spot, wherein the minimum unit of the grid matrix is ​​composed of four scanning points adjacent to each other; Obtaining pixel coordinates of each adjacent scanning point and a corresponding emission angle from the calibration relationship; The actual emission angle of the laser beam is determined based on the pixel coordinates of each adjacent scanning point, the emission angle, and the pixel coordinates of the first light spot imaged in the image obtained by the corresponding camera.

10. The method according to claim 9, wherein the pixel coordinates and the emission angle of the first adjacent scanning point are respectively (x1, y1), (θ x1 ,θ y1 ), the pixel coordinates and the emission angle of the second adjacent scanning point are (x2, y2), (θ x2 ,θ y2 ), the pixel coordinates and the emission angle of the third adjacent scanning point are (x3, y3), (θ x3 ,θ y3 ), the pixel coordinates of the first light spot imaged in the image obtained by the corresponding camera are (x, y), then the actual emission angle (θ x ,θ y )for:

Images