CN115685153A

CN115685153A - Laser radar calibration method, device, equipment and storage medium

Info

Publication number: CN115685153A
Application number: CN202110824811.3A
Authority: CN
Inventors: 朱保华; 王镇
Original assignee: Beijing Voyager Technology Co Ltd
Current assignee: Beijing Voyager Technology Co Ltd
Priority date: 2021-07-21
Filing date: 2021-07-21
Publication date: 2023-02-03

Abstract

The invention provides a laser radar calibration method, a device, equipment and a storage medium, which provide accurate vehicle pose information through the calibration pose of an inertial navigation system, sequentially and independently calibrate a plurality of laser radars by means of the calibrated vehicle pose information, and perform point cloud splicing on the plurality of laser radars to realize the joint verification of calibrated external parameters and finally obtain the accurate external parameters of each laser radar.

Description

Laser radar calibration method, device, equipment and storage medium

Technical Field

The disclosure relates to the technical field of automatic driving, in particular to a laser radar calibration method, a laser radar calibration device, laser radar calibration equipment and a storage medium.

Background

With the development and progress of science and technology, automobiles become one of the necessary transportation means for people to go out, and with the development of automobile technology, automatic driving has occupied an important position in automobile technology. The automatic driving solution depends on multi-sensor fusion, and in the multi-sensor solution, the laser radar plays an important role, such as building a high-precision map, positioning in real time and high precision, sensing obstacles in real time and the like. In an autonomous driving scenario, multiple or multiple lidar systems are typically mounted on the vehicle at different positions and orientations to obtain different orientation redundant measurements of the region of interest. Before data measurement using lidar, their external parameters (externic, consisting of position and attitude, which can be described, for example, by a 6-dimensional vector representing position coordinates and rotational attitude) need to be precisely calibrated.

At present, for parameter calibration of laser radars, a direct Iterative ICP (Iterative closed Point) mode is mostly used, but when the overlap degree of installation view angles among multiple laser radars is very small, the direct Iterative mode of the multiple laser radars cannot work normally, and the calibration accuracy is low.

Disclosure of Invention

The embodiment of the disclosure at least provides a laser radar calibration method, a laser radar calibration device, laser radar calibration equipment and a storage medium.

The embodiment of the disclosure provides a laser radar calibration method, which comprises the following steps:

calibrating an inertial navigation system on a vehicle to be calibrated in a target scene, and determining vehicle position and pose information of the vehicle to be calibrated in a scene coordinate system corresponding to the target scene;

acquiring initial point cloud data acquired by each laser radar in a plurality of laser radars installed on the vehicle to be calibrated under initial external parameters;

for each laser radar, determining a calibration external parameter of the laser radar based on the collected initial point cloud data, the vehicle pose information and the initial external parameter;

and splicing calibration point cloud data acquired by the plurality of laser radars under the calibration external parameters, and adjusting the calibration external parameters based on the spliced point cloud data.

In an optional implementation manner, calibrating, by the inertial navigation system on the vehicle to be calibrated in a target scene, and determining vehicle pose information of the vehicle to be calibrated in a scene coordinate system corresponding to the target scene includes:

acquiring inertial navigation positioning data acquired by an inertial navigation system after initialization processing on the vehicle to be calibrated in the process that the vehicle to be calibrated runs according to a preset running track in a target scene;

determining a plurality of inertial navigation positioning points positioned by the inertial navigation system in the running process of the vehicle to be calibrated and a plurality of yaw angles, output by the inertial navigation system, of the vehicle to be calibrated in the preset running track based on the inertial navigation positioning data;

determining inertial navigation positioning deviation of the inertial navigation system based on the plurality of inertial navigation positioning points and the plurality of yaw angles;

calibrating the inertial navigation system based on the inertial navigation positioning deviation, and determining inertial navigation pose information of the inertial navigation system;

and taking the inertial navigation pose information as the vehicle pose information of the vehicle to be calibrated.

In an optional embodiment, the determining an inertial navigation positioning deviation of the inertial navigation system based on the plurality of inertial navigation positioning points and the plurality of yaw angles includes:

dividing a preset running track of the vehicle to be calibrated running in a target scene into a plurality of sections of sub-running tracks;

determining a plurality of inertial navigation positioning points in each section of sub-driving track in the plurality of inertial navigation positioning points and a yaw angle in each section of sub-driving track;

aiming at each section of sub-driving track, fitting a first direction vector of the vehicle to be calibrated in the sub-driving track based on a plurality of inertial navigation positioning points corresponding to the sub-driving track;

determining a second direction vector of the vehicle to be calibrated in the sub-driving track based on the yaw angle of the vehicle to be calibrated in the sub-driving track;

determining the angle deviation of the inertial navigation system in the sub-driving track based on the first direction vector and the second direction vector of the vehicle to be calibrated in the sub-driving track;

and counting the angle deviation corresponding to each section of the sub-driving track, and determining the inertial navigation positioning deviation of the inertial navigation system.

In an optional embodiment, the determining, for each of the lidar, a calibration extrinsic parameter of the lidar based on the acquired initial point cloud data, the vehicle pose information, and the initial extrinsic parameter includes:

for each laser radar, sequentially taking a plurality of laser lines of the laser radar as target laser lines, and determining a plurality of first scanning points, scanned by the target laser lines for a target plane object in the target scene, under the scene coordinate system and a plurality of second scanning points, scanned by each adjacent laser line of the plurality of laser lines for the target plane object, under the scene coordinate system based on the initial point cloud data, the vehicle pose information and the initial external parameters;

determining a fitting plane fitted by a plurality of first scanning points corresponding to the target laser line and a total distance between a plurality of second scanning points of a plurality of adjacent laser lines corresponding to the target laser line and the fitting plane;

and adjusting the initial external parameters of the laser radar based on the determined multiple total distances to obtain the calibrated external parameters of the laser radar.

In an optional embodiment, the determining, for each of the lidar, a plurality of first scanning points in the scene coordinate system, which are scanned by the target laser line for a target planar object in the target scene, and a plurality of second scanning points in the scene coordinate system, which are scanned by each of a plurality of adjacent laser lines in the plurality of laser lines for the target laser line for the target planar object, based on the initial point cloud data, the vehicle pose information, and the initial external parameter, sequentially using the plurality of laser lines of the lidar as target laser lines, includes:

determining initial pose information of the laser radar based on the initial external parameters;

performing coordinate transformation processing on the initial point cloud data based on the corresponding relation between the initial pose information and the vehicle pose information to obtain target point cloud data of the initial point cloud data in the scene coordinate system;

and sequentially taking the plurality of laser lines of the laser radar as target laser lines, and determining a plurality of first scanning points which are scanned by the target laser lines aiming at a target plane object in a target scene and under a scene coordinate system and a plurality of second scanning points which are scanned by each adjacent laser line aiming at the target plane object and under the scene coordinate system based on the target point cloud data, wherein the adjacent laser line is any one of the plurality of laser lines which are adjacent to the target laser line.

In an alternative embodiment, the determining the total distance between the fitting plane and the second scanning points of the adjacent laser lines corresponding to the target laser line and the fitting plane includes:

fitting a plurality of first scanning points corresponding to the target laser line to obtain a fitting plane corresponding to the target laser line;

determining a target distance between each second scanning point of a plurality of second scanning points corresponding to the adjacent laser lines and the fitting plane aiming at each adjacent marking laser line corresponding to the target laser line;

and determining the total distance of the plurality of adjacent marking laser lines corresponding to the target laser line relative to the fitting plane based on the plurality of target distances corresponding to each adjacent laser line.

In an optional implementation manner, the adjusting the initial external parameter of the laser radar based on the determined plurality of total distances to obtain the calibrated external parameter of the laser radar includes:

determining a sum of distances for the plurality of laser lines based on the determined plurality of total distances;

performing iterative processing on the distance sum and the initial external parameter until the distance sum reaches the minimum value of a plurality of iterative values, and determining the external parameter of the laser radar corresponding to the distance sum which is the minimum value;

and taking the determined external parameters as the calibration external parameters of the laser radar.

In an optional embodiment, the stitching calibration point cloud data collected by the plurality of laser radars under the calibration external parameter, and adjusting the calibration external parameter based on the stitched point cloud data includes:

aiming at calibration point cloud data collected by each laser radar under corresponding calibration external parameters, based on the calibration external parameters of each laser radar, converting the calibration point cloud data of each other laser radar except for the target laser radar in the plurality of laser radars into a target radar coordinate system of the target laser radar;

and adjusting the calibration external parameters of each laser radar based on the transformed calibration point cloud data of each other laser radar and the calibration point cloud data of the target laser radar to obtain the adjusted calibration external parameters of each laser radar.

In an optional implementation manner, the adjusting the calibration external parameter of each lidar based on the transformed calibration point cloud data of each other lidar and the transformed calibration point cloud data of the target lidar to obtain the adjusted calibration external parameter of each lidar includes:

determining a scanning overlap region between each adjacent two of the plurality of lidar;

for each two adjacent laser radars, splicing the transformed calibration point cloud data of each laser radar in the two laser radars under the target radar coordinate system to obtain overlapped point cloud data corresponding to each laser radar and located in the overlapped area;

registering the point clouds indicated by the two overlapped point cloud data corresponding to the two laser radars to obtain registration deviation between the two point clouds;

and adjusting the calibrated external parameters of the two laser radars based on the registration deviation obtained by registration to obtain the calibrated external parameters of each laser radar in the two laser radars after adjustment.

The embodiment of the present disclosure further provides a laser radar calibration apparatus, the apparatus includes:

the vehicle position and orientation determining module is used for calibrating an inertial navigation system on a vehicle to be calibrated in a target scene and determining vehicle position and orientation information of the vehicle to be calibrated in a scene coordinate system corresponding to the target scene;

the system comprises an initial point cloud acquisition module, a point cloud calibration module and a point cloud calibration module, wherein the initial point cloud acquisition module is used for acquiring initial point cloud data acquired by each laser radar in a plurality of laser radars installed on a vehicle to be calibrated under an initial external parameter;

the first parameter adjusting module is used for determining a calibration external parameter of each laser radar based on the acquired initial point cloud data, the acquired vehicle pose information and the initial external parameter;

and the second parameter adjusting module is used for splicing the calibration point cloud data acquired by the plurality of laser radars under the calibration external parameters and adjusting the calibration external parameters based on the spliced point cloud data.

In an optional implementation, the vehicle pose determination module is specifically configured to:

In an optional embodiment, the vehicle pose determination module, when configured to determine the inertial navigation positioning bias of the inertial navigation system based on the plurality of inertial navigation positioning points and the plurality of yaw angles, is specifically configured to:

dividing the preset running track of the vehicle to be calibrated running in the target scene into a plurality of sections of sub-running tracks;

determining a plurality of inertial navigation positioning points in the plurality of inertial navigation positioning points for each section of sub-driving track and a yaw angle for each section of sub-driving track;

In an optional implementation manner, the first parameter adjusting module is specifically configured to:

In an optional embodiment, the first parameter adjustment module, when configured to, for each of the laser radars, sequentially use a plurality of laser lines of the laser radar as target laser lines, and determine, based on the initial point cloud data, the vehicle pose information, and the initial external parameter, a plurality of first scanning points in the scene coordinate system, which are scanned by the target laser lines for a target planar object in the target scene, and a plurality of second scanning points in the scene coordinate system, which are scanned by each of a plurality of adjacent laser lines in the plurality of laser lines for the target laser line for the target planar object, specifically is configured to:

In an alternative embodiment, the first parameter adjustment module, when configured to determine a total distance between a fitting plane fitted by a plurality of first scanning points corresponding to the target laser line and a fitting plane and a plurality of second scanning points of a plurality of adjacent laser lines corresponding to the target laser line, is specifically configured to:

In an optional implementation manner, when the first parameter adjusting module is configured to adjust an initial external parameter of the laser radar based on the determined multiple total distances to obtain a calibrated external parameter of the laser radar, the first parameter adjusting module is specifically configured to:

and taking the determined external parameters as the calibrated external parameters of the laser radar.

In an optional implementation manner, the second parameter adjusting module is specifically configured to:

In an optional implementation manner, the second parameter adjusting module is configured to, when being configured to adjust the calibration external parameter of each laser radar based on the transformed calibration point cloud data of each other laser radar and the calibration point cloud data of the target laser radar to obtain the adjusted calibration external parameter of each laser radar, specifically configured to:

An embodiment of the present disclosure further provides an electronic device, including: the laser radar calibration system comprises a processor, a memory and a bus, wherein the memory stores machine readable instructions executable by the processor, when the electronic device runs, the processor and the memory are communicated through the bus, and the machine readable instructions are executed by the processor to execute the steps of the laser radar calibration method.

The disclosed embodiment also provides a computer readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the laser radar calibration method are executed.

Embodiments of the present disclosure also provide a computer program product, which includes computer instructions, and when executed by a processor, the computer instructions implement the steps of the laser radar calibration method as described above.

According to the laser radar calibration method, the laser radar calibration device, the laser radar calibration equipment and the laser radar calibration storage medium, vehicle pose information of a vehicle to be calibrated under a scene coordinate system corresponding to a target scene is determined by calibrating an inertial navigation system on the vehicle to be calibrated in the target scene; acquiring initial point cloud data acquired by each laser radar in a plurality of laser radars installed on the vehicle to be calibrated under an initial external parameter; for each laser radar, determining a calibration external parameter of the laser radar based on the collected initial point cloud data, the vehicle pose information and the initial external parameter; and splicing calibration point cloud data acquired by the plurality of laser radars under the calibration external parameters, and adjusting the calibration external parameters based on the spliced point cloud data.

Therefore, accurate vehicle pose information is provided through the calibration pose of the inertial navigation system, the plurality of laser radars are sequentially and independently calibrated by means of the calibrated vehicle pose information, point cloud splicing is performed on the plurality of laser radars to realize the joint verification of the calibrated external parameters, and finally the accurate external parameters of each laser radar are obtained.

In order to make the aforementioned objects, features and advantages of the present disclosure more comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly described below, and the drawings herein incorporated in and forming a part of the specification illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the technical solutions of the present disclosure. It is appreciated that the following drawings depict only certain embodiments of the disclosure and are therefore not to be considered limiting of its scope, for those skilled in the art will be able to derive additional related drawings therefrom without the benefit of the inventive faculty.

Fig. 1 is a flowchart of a laser radar calibration method according to an embodiment of the present disclosure;

fig. 2 is a flowchart of inertial navigation system calibration in a laser radar calibration method according to an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of inertial navigation calibration;

fig. 4 is a flowchart of a laser radar calibration method according to an embodiment of the present disclosure;

fig. 5 is a schematic diagram of a laser radar calibration apparatus provided in an embodiment of the present disclosure;

fig. 6 is a schematic diagram of an electronic device according to an embodiment of the present disclosure.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be described clearly and completely with reference to the drawings in the embodiments of the present disclosure, and it is obvious that the described embodiments are only a part of the embodiments of the present disclosure, not all of the embodiments. The components of the embodiments of the present disclosure, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present disclosure, presented in the figures, is not intended to limit the scope of the claimed disclosure, but is merely representative of selected embodiments of the disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the disclosure without making creative efforts, shall fall within the protection scope of the disclosure.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined or explained in subsequent figures.

The term "and/or" herein merely describes an associative relationship, meaning that three relationships may exist, e.g., a and/or B, may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the term "at least one" herein means any one of a plurality or any combination of at least two of a plurality, for example, including at least one of a, B, and C, and may mean including any one or more elements selected from the group consisting of a, B, and C.

Research shows that at present, an automatic driving solution depends on multi-sensor fusion, and in the multi-sensor solution, a laser radar plays an important role, such as building a high-precision map, positioning in real time and high precision, sensing obstacles in real time and the like. However, for parameter calibration of the laser radar, a direct Iterative ICP (Iterative closed Point) mode is mostly used, but when the overlap degree of the installation view angles between the multiple laser radars is small, the direct Iterative mode of the multiple laser radars cannot work normally, and the calibration accuracy is low.

Based on the research, the laser radar calibration method is provided, accurate vehicle pose information is provided through calibration poses of an inertial navigation system, the plurality of laser radars are sequentially and independently calibrated by means of the calibrated vehicle pose information, point cloud splicing is performed on the plurality of laser radars, so that joint verification of calibrated external parameters is achieved, and finally accurate external parameters of each laser radar are obtained.

To facilitate understanding of the present embodiment, first, a detailed description is given to a lidar calibration method disclosed in an embodiment of the present disclosure, where an execution subject of the lidar calibration method provided in the embodiment of the present disclosure is generally a computer device with certain computing capability, and the computer device includes, for example: terminal equipment or servers or other processing devices. In some possible implementations, the lidar calibration method may be implemented by a processor calling computer-readable instructions stored in a memory.

Referring to fig. 1, fig. 1 is a flowchart of a laser radar calibration method according to an embodiment of the disclosure. As shown in fig. 1, a laser radar calibration method provided in the embodiment of the present disclosure includes:

s101: calibrating an inertial navigation system on a vehicle to be calibrated in a target scene, and determining vehicle pose information of the vehicle to be calibrated in a scene coordinate system corresponding to the target scene.

In the step, when a plurality of laser radars installed on a vehicle to be calibrated are calibrated, an accurate reference needs to be determined, so that an inertial navigation system on the vehicle to be calibrated can be calibrated, and vehicle position and attitude information of the vehicle to be calibrated under a scene coordinate system corresponding to a target scene is determined through parameters calibrated by the inertial navigation system in the target scene.

The target scene can be a calibration site for parameter calibration by a user, and for convenience and accuracy of calibration, the target scene can be a selected open site, and a plurality of three-dimensional reference objects such as square walls are arranged in the site, so that data can be collected and used conveniently.

At present, most vehicles are provided with inertial navigation systems, so that inertial navigation can be provided for the vehicles, the vehicles can be positioned with high precision, and accurate pose and the like can be provided. Therefore, the parameters provided by the inertial navigation system can be used as the pose of the vehicle and as one of the inputs to realize the external parameter calibration of the laser radar. The inertial navigation system needs to be initialized to be in a working state before being applied. When the inertial navigation system enters a working state, the inertial navigation system generally has an index of self-checking positioning pose stability, but the index is not enough to meet the precise external parameter calibration. Therefore, in the implementation of the present disclosure, the inertial navigation system needs to be calibrated to serve as a reference for vehicle pose information, so as to ensure the accuracy of input parameters, and to contribute to improving the stability and precision of laser radar calibration.

Specifically, please refer to fig. 2 at the same time, fig. 2 is a flowchart of inertial navigation system calibration in the laser radar calibration method provided by the embodiment of the present disclosure. As shown in fig. 2, in some possible embodiments, determining vehicle pose information through calibration of an inertial navigation system may include the following steps:

s1011: acquiring inertial navigation positioning data acquired by an inertial navigation system initialized on the vehicle to be calibrated in the process that the vehicle to be calibrated runs according to a preset running track in a target scene.

In this step, when calibrating the inertial navigation system, the inertial navigation system may be initialized first, and then the vehicle to be calibrated is controlled to travel in a target scene, for subsequent data processing and data collection simplification, the vehicle to be calibrated may travel according to a preset travel track, and in the travel process, the inertial navigation positioning data may be collected by the inertial navigation system after the initialization processing.

In practical application, for ensuring the reliability and accuracy of data acquisition, the method can be carried out in a test field for parameter calibration, and a multi-surface square wall can be arranged in the test field to be used as an object for subsequent laser radar scanning. When the inertial navigation system is calibrated, a vehicle to be calibrated can be manually driven to run for a certain distance along a straight line at a certain speed, for example, at a speed of 20-30 kilometers per hour, and the running distance is not too long due to the fact that the precision of the inertial navigation system is reduced along with the distance and time, for example, 500 meters can be run, the stability and the easiness in data acquisition can be ensured by controlling the vehicle to run at a constant speed and in a straight line, and the inertial navigation system can be controlled to collect inertial navigation positioning data.

S1012: and determining a plurality of inertial navigation positioning points positioned by the inertial navigation system in the running process of the vehicle to be calibrated and a plurality of yaw angles, output by the inertial navigation system, of the vehicle to be calibrated in the preset running track based on the inertial navigation positioning data.

In this step, after the inertial navigation positioning data is acquired, a plurality of inertial navigation positioning points positioned by the inertial navigation system in the process that the vehicle to be calibrated runs on the preset running track and a plurality of yaw angles, output by the inertial navigation system, of the vehicle to be calibrated in the preset running track can be obtained through analyzing the inertial navigation positioning data.

In the running process of the vehicle to be calibrated, the number of the plurality of inertial navigation positioning points positioned by the inertial navigation system can be preset according to factors such as precision requirements of data calibration, so that the parameters such as positioning frequency of the inertial navigation system are acquired according to the corresponding parameters such as positioning frequency during data acquisition, and the number of the inertial navigation positioning points can be output.

S1013: and determining inertial navigation positioning deviation of the inertial navigation system based on the plurality of inertial navigation positioning points and the plurality of yaw angles.

In this step, after obtaining the plurality of analyzed inertial navigation positioning points and the plurality of yaw angles output by the inertial navigation system, the plurality of inertial navigation positioning points may be fused and compared with the plurality of yaw angles, so as to obtain a difference between the two aspects, and thus obtain an inertial navigation positioning deviation of the inertial navigation system.

Specifically, for determining the inertial navigation positioning deviation of the inertial navigation system, a preset driving track of the vehicle to be calibrated running in a target scene may be divided into multiple sub-driving tracks, and the problem may be refined by dividing the sub-driving tracks, which is beneficial to improving the accuracy of the calibration result.

Then, for each segment of the sub-driving track, fitting a first direction vector of the vehicle to be calibrated running in the sub-driving track based on a plurality of inertial navigation positioning points corresponding to the sub-driving track according to the sequence of the plurality of inertial navigation positioning points and other factors, and determining a second direction vector of the vehicle to be calibrated in the sub-driving track by means of vector component analysis and the like based on the yaw angle of the vehicle to be calibrated in the sub-driving track.

Then, based on the first direction vector and the second direction vector of the vehicle to be calibrated in the sub-driving track, determining the angle deviation of the inertial navigation system in the sub-driving track through vector comparison calculation and other modes, and after obtaining the angle deviation corresponding to each section of sub-driving track, counting the angle deviation corresponding to each section of sub-driving track, thereby determining the inertial navigation positioning deviation of the inertial navigation system.

For example, please refer to fig. 3, fig. 3 is a schematic diagram of inertial navigation calibration. As shown in fig. 3, in the scene coordinate system (x, y), taking the preset driving track of the vehicle to be calibrated as a straight line of 500 meters as an example, the straight line track can be divided into about 40-50 meters, and a plurality of sub-driving tracks, such as the track l, can be divided ₁ Track l ₂ 8230and track l _n 。

For a plurality of inertial navigation positioning points positioned by an inertial navigation system and a plurality of output yaw angles, the positioning addresses of the inertial navigation positioning points and the positions of the yaw angles can be correspondingly divided into corresponding sub-driving tracks, and each section of the sub-driving tracks is provided with a plurality of discrete inertial navigation positioning points and yaw angles.

For one of the sub-tracks l _i (where i represents the sequence of the corresponding sub-driving tracks, i is the ith sub-driving track, i is greater than or equal to 1 and less than or equal to n), the inertial navigation positioning points can be positioned by using the least square methodIn an equal way, fitting to obtain a linear direction vector l _if ＝(x _if ，y _if ) Wherein l is _if Representing the trajectory l fitted by the inertial navigation setpoint _i The direction vector of (2).

Then the track l of the vehicle to be calibrated output by the inertial navigation system can be read _i Yaw angle in _i The direction vector of the inertial navigation system can be converted according to the following formula:

l _ig ＝(x _ig ，y _ig )＝(cos(yaw _i )，sin(yaw _i ))；

wherein l _ig Is represented by a track l _i Corresponding yaw angle yaw _i The calculated direction vector.

Then, pass through the trace l _i Direction vector l of _if And a direction vector l _ig The angular deviation between the two directional vectors is calculated by:

after calculating the angle deviation corresponding to each section of sub-driving track, all the angle deviations θ can be counted _n For example, the inertial navigation positioning deviation of the inertial navigation system can be finally obtained by means of averaging, variance, mean-square difference and the like.

S1014: and calibrating the inertial navigation system based on the inertial navigation positioning deviation, and determining inertial navigation pose information of the inertial navigation system.

In this step, after the inertial navigation positioning deviation is obtained, the inertial navigation system may be calibrated in a manner of iteration and the like to adjust the pose parameters and the like of the inertial navigation system until the inertial navigation positioning deviation meets the calibration precision requirement, for example, is smaller than a certain preset threshold, and the inertial navigation pose information of the inertial navigation system may be determined according to the adjusted pose parameters.

S1015: and taking the inertial navigation pose information as the vehicle pose information of the vehicle to be calibrated.

Therefore, the calibrated pose of the inertial navigation system is used as the pose of the vehicle to be calibrated, so that the pose of the vehicle to be calibrated is used as one of the inputs of subsequent data calibration, and the accuracy of subsequent data processing can be ensured.

Receiving the above S101, S102: and acquiring initial point cloud data acquired by each laser radar in the plurality of laser radars installed on the vehicle to be calibrated under initial external parameters.

In this step, after the inertial navigation system is calibrated, the vehicle to be calibrated can be controlled to run so that the plurality of laser radars are installed to acquire point cloud data, and thus, initial point cloud data acquired by each laser radar under initial external parameters is acquired.

The initial point cloud data collected by each laser radar comprises a plurality of frames of point clouds, subsequent calibration point cloud data and the like, which are the same as the initial point cloud data and are not repeated.

For example, in the test field for parameter calibration, the vehicle may be controlled to reciprocate, such as to orbit around the '8' word or around the 'o' word, so that the laser radar may perform the initial point cloud data acquisition.

S103: and aiming at each laser radar, determining the calibration external parameters of the laser radar based on the acquired initial point cloud data, the vehicle pose information and the initial external parameters.

In this step, for each lidar, the initial point cloud data, the vehicle pose information, and the initial external parameter may be used to calibrate the lidar parameters to obtain calibrated external parameters.

Therefore, each laser radar is sequentially and independently calibrated to realize the initial calibration of the external parameters, the dependence among a plurality of laser radars can be reduced or even eliminated, the vehicle pose information obtained after calibration can be accurately referred, and the accuracy of data processing is favorably ensured.

S104: and splicing calibration point cloud data acquired by the plurality of laser radars under the calibration external parameters, and adjusting the calibration external parameters based on the spliced point cloud data.

In this step, after the calibration of the parameters of each lidar is completed and the corresponding calibration external parameters are obtained, one-step verification can be performed, specifically, calibration point cloud data can be acquired through the lidar under the calibration external parameters, and a plurality of calibration point cloud data corresponding to a plurality of lidar are spliced, so that the calibration external parameters are adjusted through differences generated after splicing.

According to the laser radar calibration method provided by the embodiment of the disclosure, accurate vehicle pose information is provided through the calibration pose of the inertial navigation system, the plurality of laser radars are sequentially and independently calibrated by means of the calibrated vehicle pose information, then point cloud splicing is performed on the plurality of laser radars, so that the calibrated external parameters are jointly verified, and finally the accurate external parameters of each laser radar are obtained.

Referring to fig. 4, fig. 4 is a flowchart of a laser radar calibration method according to an embodiment of the disclosure. As shown in fig. 4, a laser radar calibration method provided in the embodiment of the present disclosure includes:

s401: calibrating an inertial navigation system on a vehicle to be calibrated in a target scene, and determining vehicle position and attitude information of the vehicle to be calibrated in a scene coordinate system corresponding to the target scene.

S402: and acquiring initial point cloud data acquired by each laser radar in the plurality of laser radars installed on the vehicle to be calibrated under initial external parameters.

S403: and aiming at each laser radar, determining a calibration external parameter of the laser radar based on the collected initial point cloud data, the vehicle pose information and the initial external parameter.

S404: and based on the calibration external parameters of each laser radar in the plurality of laser radars, performing data acquisition in a target scene to obtain calibration cloud data acquired by each laser radar under the corresponding calibration external parameters.

In the step, after each laser radar is calibrated independently to obtain the corresponding external calibration parameter, the external parameter calibration quality of the laser radar can be further performed, so that the vehicle to be calibrated can be controlled to run in the target scene again, and the calibration cloud data can be collected by each laser radar under the corresponding external calibration parameter.

S405: and splicing calibration point cloud data acquired by the plurality of laser radars under the calibration external parameters, and adjusting the calibration external parameters based on the spliced point cloud data.

The descriptions of steps S401 to S403 and S405 may refer to the descriptions of steps S101 to S104, and the same technical effect and the same technical problem may be achieved, which is not described herein again.

Next, the present embodiment will be further described with reference to some specific embodiments.

In some possible embodiments, step S403 includes:

for each lidar, sequentially taking a plurality of laser lines of the lidar as target laser lines, and determining a plurality of first scanning points, scanned by the target laser lines for a target planar object in the target scene, in the scene coordinate system and a plurality of second scanning points, scanned by each adjacent laser line of a plurality of adjacent laser lines for the target laser line in the plurality of laser lines for the target planar object, in the scene coordinate system based on the initial point cloud data, the vehicle pose information and the initial external parameters;

Specifically, for each lidar, considering that the lidar generally comprises a plurality of laser probes, a plurality of laser lines can be emitted, the plurality of laser lines of the lidar can be sequentially used as target laser lines, and a plurality of first scanning points of a target plane object in the target scene can be determined by conversion and correspondence among the initial point cloud data, the vehicle pose information and the initial external parameters, wherein one first scanning point corresponds to a scanning result of one frame of point cloud in the initial point cloud data, and further, a fitting plane can be fitted through the plurality of first scanning points.

Next, according to preset precision requirements and the like, the number of adjacent laser lines required when parameters are calibrated can be preset, for the target laser line, the adjacent laser line of the target laser line in the multiple laser lines of the laser radar can be determined, then, through the conversion and the corresponding relation among the initial point cloud data, the vehicle pose information and the initial external parameters, a plurality of second scanning points of a target plane object in the target scene scanned by each adjacent laser line under the scene coordinate system can be determined, further, the distance between the plurality of second scanning points of each adjacent laser line and the fitting plane can be calculated, and therefore the total distance between the plurality of second scanning points of the multiple adjacent laser lines corresponding to the target laser line and the fitting plane can be determined.

Then, the initial external parameter of the laser radar can be adjusted through the total distance corresponding to each target laser line, namely the total distance corresponding to each laser line, and finally the calibrated external parameter of the laser radar is obtained.

Specifically, for determining the plurality of first scanning points of the target laser line and the plurality of second scanning points of each adjacent laser line, the initial pose information of the lidar may be determined based on the initial external parameters, and the initial external parameters may include parameters such as a position and a posture of the lidar mounted on the vehicle to be calibrated, so as to determine the pose of the lidar relative to the vehicle to be calibrated.

Then, based on the corresponding relationship between the initial pose information and the vehicle pose information, coordinate transformation processing is performed on the initial point cloud data to obtain target point cloud data of the initial point cloud data in the scene coordinate system, for example, the initial point cloud data may be first converted into a vehicle coordinate system, and then the initial point cloud data is converted into the scene coordinate system by means of position coordinates and the like of a vehicle to be calibrated in the scene coordinate system to obtain corresponding target point cloud data.

And then, sequentially using the plurality of laser lines of the laser radar as target laser lines, and determining a plurality of first scanning points, which are scanned by the target laser lines aiming at a target plane object in the target scene, under the scene coordinate system and a plurality of second scanning points, which are scanned by each adjacent laser line aiming at the target plane object under the scene coordinate system, on the basis of the target point cloud data, wherein the adjacent laser line is any one of the plurality of laser lines adjacent to the target laser line.

Specifically, in some possible embodiments, the fitting plane and the total distance corresponding to the target laser line may be obtained by fitting a plurality of first scanning points corresponding to the target laser line by using a method such as linear fitting, so as to obtain a fitting plane corresponding to the target laser line, then determining, for each adjacent target laser line corresponding to the target laser line, a target distance between each second scanning point of a plurality of second scanning points corresponding to the adjacent laser lines and the fitting plane, and determining, based on a plurality of target distances corresponding to each adjacent laser line, a total distance of the plurality of adjacent target laser lines corresponding to the target laser line with respect to the fitting plane.

The target distance between each second scanning point and the fitting plane may be obtained by calculating a distance between the second scanning point and the corresponding plane point through a coordinate of the second scanning point in the scene coordinate system and a coordinate of a plane point on the corresponding fitting plane in the scene coordinate system, and then calculating a component of the distance between the two points on a normal vector by using the normal vector of the fitting plane (e.g., a normal vector from the plane point), so as to obtain the target distance between the second scanning point and the fitting plane.

Specifically, in some possible embodiments, the initial external parameter of the laser radar is adjusted based on the determined total distances to obtain the calibrated external parameter of the laser radar, which may be based on the determined total distances to determine a sum of distances for the plurality of laser lines, for example, the total distance corresponding to each laser line of the laser radar, that is, the total distance corresponding to each target laser line, is accumulated to obtain the sum of distances for the plurality of laser lines of the laser radar.

Then, the distance sum and the initial external parameter are subjected to iteration processing until the distance sum reaches the minimum value in a plurality of iteration values, and the external parameter of the laser radar corresponding to the distance sum which is the minimum value is determined. And finally, taking the determined external parameters as the calibrated external parameters of the laser radar.

In another specific embodiment, for the optimization method used for performing the iterative processing on the sum of distances and the initial external parameters, the optimization method may be selected according to a specific installation error and an installation measurement error, and for different tolerances of the optimization objective function and the optimization initial value, specifically, when the initial value position error does not exceed 10 centimeters and the angle error does not exceed 2 degrees, the external parameters may be optimized by using a coordinate descent method, so that the convergence of the calculation process is faster.

For example, in a specific application, the target distance of an adjacent target laser line corresponding to the target laser line relative to the fitting plane may be calculated by the following formula:

wherein D is _a The sum of the distances of an adjacent target laser line corresponding to the target laser line (the a-th laser line in the laser radar) relative to the fitting plane, p is a random plane point on the fitting plane, c is the number of a plurality of second scanning points of an adjacent laser line corresponding to the target laser line, p is the number of the second scanning points of the adjacent laser line _b Is the b-th second scanning point, ξ _p Is the normal vector of the fitted plane at point p.

For each scanning point, the coordinate representation can be carried out under the scene coordinate system, so that the initial pose information of the laser radar, namely the related information of the initial external parameters,

further, the target distances corresponding to each adjacent laser line of the target laser line are accumulated, so that the total distance of the plurality of adjacent target laser lines corresponding to the target laser line relative to the fitting plane can be obtained.

Further still, the sum of the distances of the multiple laser lines for the lidar may be calculated by the following equation:

f is the sum of the distances of the laser lines of the laser radar, 2n is the number of adjacent laser lines of the parameter calculation distance, and A is the number of the laser lines of the laser radar.

In some possible embodiments, step S405 includes:

In this step, calibration point cloud data acquired by each lidar under corresponding calibration external parameters may be converted to a target radar coordinate system of the target lidar by using one lidar as a reference, that is, any one lidar selected from the plurality of radars as a target lidar, through coordinate conversion and other manners, and then the plurality of calibration point clouds in the plurality of calibration point cloud data are spliced under the target radar coordinate of the target lidar, so that the calibration external parameters of each lidar are adjusted through the spliced point clouds, and the calibration external parameters after adjustment of each lidar are obtained.

Specifically, the adjustment of the calibration extrinsic parameters may be performed by determining a scanning overlap area between each two adjacent laser radars in the plurality of laser radars, and then splicing the transformed calibration point cloud data of each laser radar in the two laser radars under the target radar coordinate system for each two adjacent laser radars to obtain the overlap point cloud data corresponding to each laser radar and located in the overlap area;

and then, registering the point clouds indicated by the two overlapped point cloud data corresponding to the two laser radars to obtain a registration deviation between the two point clouds, and then adjusting the calibration external parameters of the two laser radars based on the registration deviation obtained by registration to obtain the calibration external parameters of each laser radar in the two laser radars after adjustment.

According to the laser radar calibration method provided by the embodiment of the disclosure, accurate vehicle pose information is provided through the calibration pose of the inertial navigation system, the plurality of laser radars are sequentially and independently calibrated by means of the calibrated vehicle pose information, point cloud splicing is performed on calibration point clouds acquired by the plurality of laser radars, so that the calibrated external parameters are jointly verified, and finally the accurate external parameters of each laser radar are obtained.

It will be understood by those skilled in the art that in the method of the present invention, the order of writing the steps does not imply a strict order of execution and any limitations on the implementation, and the specific order of execution of the steps should be determined by their function and possible inherent logic.

Based on the same inventive concept, the embodiment of the present disclosure further provides a lidar calibration apparatus corresponding to the lidar calibration method, and because the principle of the apparatus in the embodiment of the present disclosure for solving the problem is similar to that of the lidar calibration method in the embodiment of the present disclosure, the implementation of the apparatus may refer to the implementation of the method, and repeated details are not repeated.

Referring to fig. 5, fig. 5 is a schematic diagram of a laser radar calibration apparatus according to an embodiment of the present disclosure. As shown in fig. 5, the lidar calibration apparatus provided in the embodiment of the present disclosure includes:

the vehicle pose determining module 510 is configured to calibrate an inertial navigation system on a vehicle to be calibrated in a target scene, and determine vehicle pose information of the vehicle to be calibrated in a scene coordinate system corresponding to the target scene.

An initial point cloud obtaining module 520, configured to obtain initial point cloud data acquired by each lidar of the multiple lidar installed on the vehicle to be calibrated under an initial external parameter.

A first parameter adjusting module 530, configured to determine, for each of the lidar, a calibration extrinsic parameter of the lidar based on the acquired initial point cloud data, the vehicle pose information, and the initial extrinsic parameter.

A second parameter adjusting module 540, configured to splice calibration point cloud data acquired by the plurality of laser radars under the calibration external parameters, and adjust the calibration external parameters based on the spliced point cloud data.

In an optional embodiment, the vehicle pose determination module 510 is specifically configured to:

In an optional embodiment, the vehicle pose determination module 510, when configured to determine the inertial navigation positioning bias of the inertial navigation system based on the plurality of inertial navigation positioning points and the plurality of yaw angles, is specifically configured to:

In an optional implementation manner, the first parameter adjusting module 530 is specifically configured to:

In an optional embodiment, the first parameter adjusting module 530 is specifically configured to, for each of the laser radars, sequentially use a plurality of laser lines of the laser radar as target laser lines, and based on the initial point cloud data, the vehicle pose information and the initial external parameters, determine a plurality of first scanning points in the scene coordinate system, which are scanned by the target laser lines for a target planar object in the target scene, and a plurality of second scanning points in the scene coordinate system, which are scanned by each of a plurality of adjacent laser lines in the plurality of laser lines for the target laser line for the target planar object, wherein the plurality of second scanning points in the scene coordinate system are scanned by the target laser lines for the target planar object:

based on the corresponding relation between the initial pose information and the vehicle pose information, carrying out coordinate transformation processing on the initial point cloud data to obtain target point cloud data of the initial point cloud data under the scene coordinate system;

and sequentially taking the plurality of laser lines of the laser radar as target laser lines, and determining a plurality of first scanning points, which are scanned by the target laser lines aiming at a target plane object in a target scene, under a scene coordinate system and a plurality of second scanning points, which are scanned by each adjacent laser line aiming at the target plane object under the scene coordinate system, on the basis of the target point cloud data, wherein the adjacent laser line is any one of the plurality of laser lines adjacent to the target laser line.

In an alternative embodiment, the first parameter adjustment module 530, when being configured to determine the total distance between the fitting plane and the plurality of first scanning points of the plurality of adjacent laser lines corresponding to the target laser line and the fitting plane and the plurality of second scanning points of the plurality of adjacent laser lines corresponding to the target laser line, is specifically configured to:

In an optional embodiment, when the first parameter adjusting module 530 is configured to adjust the initial external parameter of the lidar based on the determined multiple total distances to obtain the calibrated external parameter of the lidar, the first parameter adjusting module is specifically configured to:

In an optional implementation manner, the second parameter adjusting module 540 is specifically configured to:

In an optional implementation manner, the second parameter adjusting module 540 is specifically configured to, when configured to adjust the calibration external parameter of each lidar based on the transformed calibration point cloud data of each other lidar and the calibration point cloud data of the target lidar, and obtain the adjusted calibration external parameter of each lidar:

The laser radar calibration device provided by the embodiment of the disclosure provides accurate vehicle pose information through the calibration pose of the inertial navigation system, sequentially and independently calibrates a plurality of laser radars by means of the calibrated vehicle pose information, and then performs point cloud splicing on the plurality of laser radars so as to realize the joint verification of calibrated external parameters, and finally obtain the accurate external parameters of each laser radar.

The description of the processing flow of each module in the apparatus and the interaction flow between the modules may refer to the relevant description in the above method embodiments, and will not be described in detail here.

Corresponding to the laser radar calibration method, an embodiment of the present disclosure further provides an electronic device 600, as shown in fig. 6, which is a schematic structural diagram of the electronic device 600 provided in an embodiment of the present disclosure, and includes:

a processor 610, a memory 620, and a bus 630; the storage 620 is used for storing execution instructions and includes a memory 621 and an external storage 622; the memory 621 is also referred to as an internal memory, and is used for temporarily storing operation data in the processor 610 and data exchanged with an external memory 622 such as a hard disk, the processor 610 exchanges data with the external memory 622 through the memory 621, and when the electronic device 600 operates, the processor 610 and the memory 620 communicate through the bus 630, so that the processor 610 can execute the steps of the laser radar calibration method.

The embodiments of the present disclosure also provide a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the steps of the laser radar calibration method described in the above method embodiments are executed. The storage medium may be a volatile or non-volatile computer-readable storage medium.

Embodiments of the present disclosure further provide a computer program product, which includes computer instructions, and when the computer instructions are executed by a processor, the steps of the laser radar calibration method described above are implemented, for which reference may be made specifically to the above method embodiments, which are not described herein again.

The computer program product may be implemented by hardware, software or a combination thereof. In an alternative embodiment, the computer program product is embodied in a computer storage medium, and in another alternative embodiment, the computer program product is embodied in a Software product, such as a Software Development Kit (SDK), or the like.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the system and the apparatus described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again. In the several embodiments provided in the present disclosure, it should be understood that the disclosed system, apparatus, and method may be implemented in other ways. The above-described apparatus embodiments are merely illustrative, and for example, the division of the units into only one type of logical function may be implemented in other ways, and for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not implemented. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection of devices or units through some communication interfaces, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present disclosure may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

The functions, if implemented in software functional units and sold or used as a stand-alone product, may be stored in a non-transitory computer-readable storage medium executable by a processor. Based on such understanding, the technical solution of the present disclosure may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present disclosure. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

Finally, it should be noted that: the above-mentioned embodiments are merely specific embodiments of the present disclosure, which are used for illustrating the technical solutions of the present disclosure and not for limiting the same, and the scope of the present disclosure is not limited thereto, and although the present disclosure is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive of the technical solutions described in the foregoing embodiments or equivalent technical features thereof within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the embodiments of the present disclosure, and should be construed as being included therein. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

The embodiment of the disclosure at least provides a laser radar calibration method, a device, equipment and a storage medium.

TS1, a laser radar calibration method, wherein the method comprises the following steps:

calibrating an inertial navigation system on a vehicle to be calibrated in a target scene, and determining vehicle pose information of the vehicle to be calibrated in a scene coordinate system corresponding to the target scene;

The TS2 and the method according to the TS1, wherein the step of calibrating the inertial navigation system on the vehicle to be calibrated in a target scene and determining the vehicle position and pose information of the vehicle to be calibrated in a scene coordinate system corresponding to the target scene comprises the following steps:

acquiring inertial navigation positioning data acquired by an inertial navigation system initialized on the vehicle to be calibrated in the process that the vehicle to be calibrated runs according to a preset running track in a target scene;

The method of TS3, according to TS2, wherein the determining an inertial navigation positioning deviation of the inertial navigation system based on the plurality of inertial navigation positioning points and the plurality of yaw angles includes:

The TS4 and the method of TS1, wherein the step of determining the calibration external parameters of the laser radars based on the acquired initial point cloud data, the acquired vehicle pose information and the initial external parameters for each laser radar comprises the following steps:

The method of TS5, according to TS4, wherein the determining, for each of the lidar, a plurality of first scan points in the scene coordinate system that are scanned by the target laser line for a target planar object in the target scene and a plurality of second scan points in the scene coordinate system that are scanned by each of a plurality of adjacent laser lines in the plurality of laser lines for the target laser line for the target planar object based on the initial point cloud data, the vehicle pose information, and the initial external parameter includes:

The method of TS6, TS4, wherein the determining the total distance between the fitting plane and the fitting plane fitted by the first scanning points corresponding to the target laser line and the second scanning points of the adjacent laser lines corresponding to the target laser line comprises:

TS7, the method according to TS4, wherein the adjusting the initial external parameters of the laser radar based on the determined total distances to obtain the calibrated external parameters of the laser radar comprises:

TS8, the method according to TS1, wherein the splicing of calibration point cloud data collected by the plurality of laser radars under the calibration external parameters and the adjustment of the calibration external parameters based on the spliced point cloud data comprises the following steps:

The TS9 and the method according to TS8, wherein the step of adjusting the calibration external parameters of each laser radar based on the transformed calibration point cloud data of each other laser radar and the calibration point cloud data of the target laser radar to obtain the adjusted calibration external parameters of each laser radar comprises the following steps:

TS10, a lidar calibration device, wherein, the device includes:

the vehicle pose determining module is used for calibrating an inertial navigation system on a vehicle to be calibrated in a target scene and determining vehicle pose information of the vehicle to be calibrated under a scene coordinate system corresponding to the target scene;

TS11, an electronic device, comprising: a processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor, the processor and the memory communicate with each other via the bus when the electronic device is running, and the machine-readable instructions, when executed by the processor, perform the steps of the lidar calibration method as set forth in any one of TS1 to TS 9.

TS12, a computer-readable storage medium, wherein the computer-readable storage medium has a computer program stored thereon, and the computer program is executed by a processor to perform the steps of the lidar calibration method as set forth in any one of TS1 to TS 9.

TS13, a computer program product comprising computer instructions, wherein the computer instructions, when executed by a processor, implement the steps of the lidar calibration method according to any of TS1 to TS 9.

Claims

1. A laser radar calibration method is characterized by comprising the following steps:

2. The method according to claim 1, wherein the calibrating the inertial navigation system on the vehicle to be calibrated in a target scene, and determining the vehicle pose information of the vehicle to be calibrated in a scene coordinate system corresponding to the target scene comprises:

3. The method of claim 1, wherein the determining, for each of the lidar, calibrated external parameters of the lidar based on the acquired initial point cloud data, the vehicle pose information, and the initial external parameters comprises:

4. The method as claimed in claim 3, wherein said determining, for each of the lidar, a plurality of first scan points in the scene coordinate system that were scanned by the target laser line for a target planar object in the target scene and a plurality of second scan points in the scene coordinate system that were scanned by each of a plurality of neighboring laser lines in the plurality of laser lines for the target planar object based on the initial point cloud data, the vehicle pose information, and the initial extrinsic parameters, using the plurality of laser lines of the lidar in sequence as target laser lines, comprises:

5. A method as claimed in claim 3 wherein said determining a fitted plane to which said first plurality of scan points corresponding to said target laser line are fitted and a total distance between said fitted plane and said second plurality of scan points of said adjacent plurality of laser lines corresponding to said target laser line comprises:

6. The method of claim 3, wherein adjusting the initial extrinsic parameter of the lidar to obtain a calibrated extrinsic parameter of the lidar based on the determined plurality of total distances comprises:

7. A lidar calibration apparatus, comprising:

8. An electronic device, comprising: a processor, a memory and a bus, the memory storing machine-readable instructions executable by the processor, the processor and the memory communicating via the bus when the electronic device is running, the machine-readable instructions when executed by the processor performing the steps of the lidar calibration method as defined in any of claims 1 to 6.

9. A computer-readable storage medium, having stored thereon a computer program which, when being executed by a processor, carries out the steps of the lidar calibration method as defined in any of claims 1 to 6.

10. A computer program product comprising computer instructions, characterized in that said computer instructions, when executed by a processor, implement the steps of a lidar calibration method according to any of claims 1 to 6.