Laser radar calibration method and device for indoor distribution robot and storage medium

Abstract

The application provides a kind of indoor distribution robot laser radar calibration method, device and storage medium, including preset calibration scene, the chassis is placed in the calibration scene according to predetermined direction, the center radar used in calibration is placed in the center of the chassis, the front laser radar, the rear laser radar and the center radar are scanned the marker, with the center coordinate system as reference, the slope angle yaw of the front laser radar and the rear laser radar is calibrated, with the center coordinate system as reference, the x, y of the installation pose of the front laser radar and the rear laser radar in the center coordinate system is calibrated.The application can automatically generate calibration parameters according to the structure and laser radar installation deviation of each distribution robot, realize the installation position calibration of distribution robot double laser radar, and greatly improve the calibration efficiency and precision.

Description

Technical Field

[0001] This application relates to the field of indoor delivery robot technology, specifically to a method, device, and storage medium for calibrating a lidar for an indoor delivery robot. Background Technology

[0002] Indoor delivery robots are commonly used for transporting ordinary items, food, and fragile goods indoors. To meet the delivery volume per trip, delivery robots are typically equipped with multi-level shelves and have a rectangular chassis. To enable autonomous walking and 360-degree scene perception, the robot generally uses two single-line LiDAR sensors deployed diagonally at 45 degrees to the front and rear of the chassis. The front LiDAR is responsible for sensing the front and left sides, while the rear LiDAR is responsible for sensing the rear and right sides. Therefore, the detection accuracy of the front and rear LiDAR sensors directly affects the stability of the delivery robot's walking and navigation.

[0003] Currently, the following points are generally used in existing technologies to ensure the scanning effect of front and rear LiDAR:

[0004] (1) Use higher precision radar;

[0005] (2) Improve the installation accuracy of the radar;

[0006] (3) Perform radar calibration manually, etc.

[0007] The above calibration methods all use the same set of adjustment parameters, which cannot take into account the differences of individual robots, so accuracy cannot be guaranteed. In addition, manual adjustment is very inefficient and cannot be done in batches. Summary of the Invention

[0008] In view of the above problems, this application provides a method, device and storage medium for calibrating a lidar for an indoor delivery robot, to solve the technical problems of poor calibration accuracy and low efficiency of the delivery robot.

[0009] To achieve the above objectives, the inventors provide a method for calibrating a lidar system for an indoor delivery robot. The indoor delivery robot includes a front lidar and a rear lidar, which are diagonally mounted on the chassis of the robot. The calibration method includes the following steps:

[0010] A preset calibration scenario includes a preset front panel and a rear panel that are parallel to each other, with markers affixed to the middle portions of the front panel and the rear panel respectively;

[0011] The chassis is placed in the calibration scene in a predetermined direction, and the central radar used for calibration is placed in the center of the chassis. The central radar is a 360-degree lidar.

[0012] Coordinate systems are established for the front lidar, the rear lidar, and the central lidar, respectively, and the marker is scanned by the front lidar, the rear lidar, and the central lidar, respectively, with the coordinate system of the central lidar being the central coordinate system;

[0013] The scanning data of the front lidar and the scanning data of the rear lidar are converted from polar coordinates to Cartesian coordinates (x, y).

[0014] Divide the Cartesian coordinate system points of the front and rear lidars into two groups of data with the center of the chassis as the boundary, and calculate the centroids of the front and rear groups of data respectively. The centroid of the front group of data is the front centroid, and the centroid of the rear group of data is the rear centroid.

[0015] Using the central coordinate system as a reference, the slope angle yaw of the front lidar and the rear lidar is calibrated, where yaw = atan2((rzy-bzy),(rzx-bzx)), where rzy is the y-coordinate value of the front centroid, bzy is the y-coordinate value of the rear centroid, rzx is the x-coordinate value of the front centroid, and bzx is the x-coordinate value of the rear centroid.

[0016] Using the central coordinate system as a reference, the x and y coordinates of the installation poses of the front and rear lidars within the central coordinate system are calibrated.

[0017] In some technical solutions, the calibration of the x and y coordinates of the installation pose of the front and rear lidars in the central coordinate system, using the central coordinate system as a reference, includes the following steps:

[0018] The scanning data of the front lidar and the scanning data of the rear lidar are converted from polar coordinates to Cartesian coordinates (x, y).

[0019] Calculate the anterior centroid and the rear centroid;

[0020] The x-axis and y-axis coordinates of the front centroid and the rear centroid are summed and their average absolute values ​​are taken to obtain (cfx, cfy) and (cbx, cby), where cfx is the average absolute value of the x-axis of the front centroid, cfy is the average absolute value of the y-axis of the front centroid, cbx is the average absolute value of the x-axis of the rear centroid, and cby is the average absolute value of the y-axis of the rear centroid.

[0021] Projecting fx, fy, bx, and by into the central coordinate system yields ftx, fty, btx, and bty, where fx is the sum of the x-axis coordinates of the front and rear centroids of the front LiDAR scan data, fy is the sum of the y-axis coordinates of the front and rear centroids of the front LiDAR scan data, bx is the sum of the x-axis coordinates of the front and rear centroids of the rear LiDAR scan data, and by is the sum of the y-axis coordinates of the front and rear centroids of the rear LiDAR scan data.

[0022] According to the formulas tx=x*cos(yaw)+y*sin(yaw) and ty=y*cos(yaw)-x*sin(yaw), calculate the projected distance values ​​of the front lidar and the rear lidar in the x-axis and y-axis directions of the central coordinate system, where tx is the projected distance value in the x-axis direction and ty is the projected distance value in the y-axis direction.

[0023] According to the formula: x-axis calibration value of the front lidar = cfx – ftx;

[0024] The y-axis calibration value of the front lidar is cfy – fty;

[0025] The x-axis calibration value of the rear lidar is -(cbx-btx);

[0026] The y-axis calibration value of the rear lidar is -(cby-bty);

[0027] Calculate the calibration values ​​of the front lidar and the rear lidar in the x-axis and y-axis directions;

[0028] The calibration values ​​of the front and rear lidars in the x and y axes are stored in the indoor delivery robot registration file.

[0029] In some technical solutions, the step of projecting fx, fy, bx, by onto the central coordinate system to obtain ftx, fty, btx, and bty includes the following steps:

[0030] The coordinate systems of the front and rear lidars are rotated so that their x and y axes are aligned with the central coordinate system.

[0031] In some technical solutions, when scanning the marker using the front lidar, the rear lidar, and the central lidar, the front lidar, the rear lidar, and the central lidar each scan the marker a preset number of times, and then the scan data are accumulated and averaged.

[0032] In some technical solutions, when scanning the marker using the front lidar, the rear lidar, and the central lidar, the front lidar intercepts laser data from -180° to 90° and retains the high-intensity portion of the data; the central lidar intercepts laser data from -90° to 90° and retains the high-intensity portion of the data as CFSCAN; the central lidar intercepts laser data from 90° to 180° and from -180° to -90° and retains the high-intensity portion of the data as CBSCCAN; the rear lidar intercepts laser data from -180° to 90° and retains the high-intensity portion of the data.

[0033] In some technical solutions, the marker is a reflective strip, and the length of the marker is 0.4 meters to 0.8 meters.

[0034] To solve the above-mentioned technical problems, the present invention also provides another technical solution:

[0035] A lidar calibration device for an indoor delivery robot, the indoor delivery robot including a front lidar and a rear lidar, the front lidar and the rear lidar being diagonally arranged on the chassis of the indoor delivery robot; comprising:

[0036] The preset module is used to preset a calibration scene, which includes preset front and rear panels that are parallel to each other, and the middle part of the front and rear panels is respectively affixed with markers; the chassis is placed in the calibration scene, and the central radar used for calibration is placed in the center of the chassis, and the central radar is a 360-degree lidar.

[0037] The scanning module is used to establish coordinate systems for the front lidar, the rear lidar, and the central lidar respectively, and to scan the marker through the front lidar, the rear lidar, and the central lidar respectively, wherein the coordinate system of the central lidar is the central coordinate system;

[0038] The calculation module is used to convert the scanning data of the front lidar and the scanning data of the rear lidar from the polar coordinate system to the rectangular coordinate system (x,y).

[0039] Divide the Cartesian coordinate system points of the front and rear lidars into two groups of data with the center of the chassis as the boundary, and calculate the centroids of the front and rear groups of data respectively. The centroid of the front group of data is the front centroid, and the centroid of the rear group of data is the rear centroid.

[0040] Using the central coordinate system as a reference, the slope angle yaw of the front lidar and the rear lidar is calibrated, where yaw = atan2((rzy-bzy),(rzx-bzx)), where rzy is the y-coordinate value of the front centroid, bzy is the y-coordinate value of the rear centroid, rzx is the x-coordinate value of the front centroid, and bzx is the x-coordinate value of the rear centroid.

[0041] Using the central coordinate system as a reference, the x and y coordinates of the installation poses of the front and rear lidars within the central coordinate system are calibrated.

[0042] In some technical solutions, the marker is a reflective strip, and the length of the marker is 0.4 meters to 0.8 meters.

[0043] In some technical solutions, when scanning the marker using the front lidar, the rear lidar, and the central lidar, the front lidar, the rear lidar, and the central lidar each scan the marker a preset number of times, and then the scan data are accumulated and averaged.

[0044] To solve the above-mentioned technical problems, the present invention also provides another technical solution:

[0045] A computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, performs the steps of the lidar calibration method for indoor delivery robots as described in any of the above technical solutions.

[0046] Unlike existing technologies, the above-mentioned technical solution, by pre-setting a calibration scenario and using a central radar, front lidar, and rear lidar to scan the same marker within that scenario, can automatically calculate the coordinate deviation between the front and rear lidars and obtain the corresponding x, y, and yaw calibration parameters through coordinate transformation and centroid calculation. This calibration method can automatically generate calibration parameters based on the structure of each delivery robot and the installation deviation of the lidars, achieving calibration of the installation position of the dual lidars on the delivery robot and significantly improving calibration efficiency and accuracy.

[0047] The above description of the invention is merely an overview of the technical solution of this application. In order to enable those skilled in the art to better understand the technical solution of this application and to implement it based on the description and drawings, and to make the above-mentioned objectives and other objectives, features and advantages of this application easier to understand, the following description is provided in conjunction with the specific embodiments and drawings of this application. Attached Figure Description

[0048] The accompanying drawings are only used to illustrate the principles, implementation methods, applications, features, and effects of specific embodiments of the present invention and other related contents, and should not be considered as limitations on this application.

[0049] In the accompanying drawings of the instruction manual:

[0050] Figure 1 A flowchart illustrating the laser radar calibration method for indoor delivery robots described in this specific implementation;

[0051] Figure 2 This is a schematic diagram illustrating the calibration of the delivery robot in a calibration scenario as described in a specific implementation.

[0052] Figure 3 This is a schematic diagram illustrating the angle range division of the lidar as described in a specific implementation method;

[0053] Figure 4 A schematic diagram illustrating the slope angle of the front lidar as described in the specific implementation method;

[0054] Figure 5 This is a schematic diagram illustrating the slope angle of the rear lidar as described in the specific implementation method;

[0055] Figure 6 This is a block diagram of the lidar calibration device for the indoor delivery robot described in a specific implementation.

[0056] Figure 7 This is a schematic diagram of the structure of the storage medium described in a specific embodiment;

[0057] The reference numerals used in the above figures are explained as follows:

[0058] 600. Indoor delivery robot lidar calibration device;

[0059] 610. Preset module; 620. Scanning module; 630. Calculation module;

[0060] 700. Computer-readable storage medium; Detailed Implementation

[0061] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this application in detail, the following description, in conjunction with the listed specific embodiments and accompanying drawings, provides a detailed explanation. The embodiments described herein are merely illustrative of the technical solutions of this application and are therefore intended to limit the scope of protection of this application.

[0062] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0063] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0064] In the description of this application, the term "and / or" is used to describe the logical relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A exists, B exists, and A and B exist simultaneously. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" logical relationship.

[0065] In this application, terms such as “first” and “second” are used only to distinguish one entity or operation from another, and do not necessarily require or imply any actual quantity, hierarchy or order relationship between these entities or operations.

[0066] Without further limitations, the use of terms such as “comprising,” “including,” “having,” or other similar open-ended expressions in this application is intended to cover non-exclusive inclusion, which does not exclude the presence of additional elements in a process, method, or product that includes the stated elements, such that a process, method, or product that includes a list of elements may include not only those defined elements but also other elements not expressly listed, or elements inherent to such a process, method, or product.

[0067] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceeding" are understood to exclude the stated number; expressions such as "above," "below," and "within" are understood to include the stated number. Furthermore, in the description of the embodiments in this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times," unless otherwise explicitly specified.

[0068] In the description of the embodiments of this application, the space-related expressions used, such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "vertical," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," indicate the orientation or positional relationship based on the orientation or positional relationship shown in the specific embodiments or drawings. They are only for the purpose of describing the specific embodiments of this application or for the reader's understanding, and do not indicate or imply that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0069] Unless otherwise expressly specified or limited, the terms "installation," "connection," "linking," "fixing," and "setting," as used in the description of the embodiments of this application, should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two components or the interaction between two components. For those skilled in the art to which this application pertains, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0070] Please see Figures 1 to 5 This embodiment describes a LiDAR calibration method for an indoor delivery robot. For example... Figure 1 As shown, the indoor delivery robot lidar calibration method includes a front lidar and a rear lidar, which are diagonally mounted on the chassis of the indoor delivery robot. The indoor delivery robot lidar calibration method includes the following steps:

[0071] S101. A preset calibration scenario, including a preset front panel and a rear panel that are parallel to each other, with markers affixed to the middle parts of the front panel and the rear panel respectively;

[0072] S102. Place the chassis in the calibration scene in a predetermined direction, and place the central radar used for calibration in the center of the chassis. The central radar is a 360-degree lidar.

[0073] S103. Establish coordinate systems for the front lidar, the rear lidar, and the central lidar respectively, and scan the marker through the front lidar, the rear lidar, and the central lidar respectively, wherein the coordinate system of the central lidar is the central coordinate system;

[0074] S104. Using the central coordinate system as a reference, calibrate the slope angle yaw of the front lidar and the rear lidar.

[0075] S105. Using the central coordinate system as a reference, calibrate the x and y coordinates of the installation pose of the front lidar and the rear lidar in the central coordinate system.

[0076] The calibration of the slope angle yaw of the front and rear lidars, using the central coordinate system as a reference, includes:

[0077] The scanning data of the front lidar and the scanning data of the rear lidar are converted from polar coordinates to Cartesian coordinates (x, y).

[0078] Divide the Cartesian coordinate system points of the front and rear lidars into two groups of data with the center of the chassis as the boundary, and calculate the centroids of the front and rear groups of data respectively. The centroid of the front group of data is the front centroid, and the centroid of the rear group of data is the rear centroid.

[0079] Using the central coordinate system as a reference, the slope angle yaw of the front lidar and the rear lidar is calibrated, where yaw = atan2((rzy-bzy),(rzx-bzx)), where rzy is the y-coordinate value of the front centroid, bzy is the y-coordinate value of the rear centroid, rzx is the x-coordinate value of the front centroid, and bzx is the x-coordinate value of the rear centroid.

[0080] like Figure 1 As shown in the attached diagram, the rectangular frame in the center represents the chassis of the indoor delivery robot. The front and rear of the chassis are flat front and rear panels, respectively. The deepened portions in the middle of the front and rear panels are identification elements, which are symmetrically arranged on the front and rear panels. The horizontal dashed line in the center of the rectangular frame is the transverse center line, which coincides with the plane of the lidar. Preferably, the identification element is a reflective strip, with a length of 0.4 meters to 0.8 meters; in one embodiment, the reflective strip is preferably 0.6 meters long. In other embodiments, the identification element can be a reflector or reflective sheet, or other materials that can effectively reflect the laser beam. Reflective strips are used as the identification element in the following embodiments.

[0081] Figure 2 The middle arrow points in front of the indoor delivery robot. The middle radar is a 360-degree rotating single-line LiDAR. The chassis and the middle radar are positioned precisely by tooling in the calibration scene. The (x, y, yaw) coordinates of the front and rear LiDARs are calibrated using the middle radar.

[0082] like Figure 2As shown, the chassis from the production line is first placed in the calibration scene as required; then, the 360-degree single-line lidar for calibration is placed in the center of the chassis using a specific fixture. When placing the central lidar, sufficient precision is required. Then, the front and rear reflective strips are identified using the front lidar, central lidar, and rear lidar respectively.

[0083] (1) Each radar shines light into the calibrated scene and achieves ranging by receiving the reflected light from the scene; in addition to ranging, the lidar can also calculate the intensity of the reflected light; the intensity of the reflected light from the reflective strip is significantly greater than the intensity of the reflected light from the surrounding scene. In some embodiments, in order to filter out the jitter of the laser data, the average of 10 data acquisitions is calculated to filter out jitter errors;

[0084] (2) The front lidar identifies reflective strips and captures lidar data from -180° to 90°. The lidar data angle distribution is as follows: Figure 2 The high-intensity portion of the data is selected, which is the laser data corresponding to the reflective strip (simple scene, no interference), and the data is saved by fscan;

[0085] (3) The middle radar identifies the reflective strip, extracts the laser data from -90° to 90°, selects the high intensity part of the data, which is the laser data corresponding to the front reflective strip, and saves the data cfscan; and extracts the laser data from 90° to 180° and -180° to -90°, selects the high intensity part of the data, which is the laser data corresponding to the rear reflective strip, and saves the data cbscan;

[0086] (4) The laser radar identifies the reflective strips, extracts laser data from -180° to 90°, and selects the high-intensity part of the data, which is the laser data corresponding to the reflective strips (simple scene, no interference), and saves the data bscan;

[0087] (5) The interception principle is related to laser deployment; see [link / reference] Figure 2 Both the front and rear lidars illuminate the robot within a 90-degree range, and the data within this range is unusable and needs to be cut off.

[0088] In step S104, using the central coordinate system as a reference, the yaw of the installation pose of the front and rear radars in this coordinate system is calibrated, including the following steps:

[0089] (1) Calculate the slope angle of the straight line formed by the scanning data fscan of the front lidar in the coordinate system of the front lidar; calculate the slope angle of the straight line formed by the scanning data bscan of the rear lidar in the coordinate system of the rear lidar.

[0090] (2) Principle of slope angle calculation:

[0091] a. Laser data consists of polar coordinate points with a resolution of 0.03 degrees, in the format (r, ang), which represents length and angle. First, convert the polar coordinate points to Cartesian coordinate points (x, y).

[0092] Coordinate x = cosine of angle multiplied by distance measured, coordinate y = sine of angle multiplied by distance measured; that is, x = cos(ang) * r; y = sin(ang) * r;

[0093] b. Divide the fscan data into two groups with the center as the boundary, and find the centroid of the two groups respectively.

[0094] c. Divide the bscan data into two groups with the center as the boundary, and find the centroid of the two groups respectively.

[0095] The first dataset consists of sets(rx, ry), with a count of rnum and an anterior centroid:

[0096] The first centroid x = the sum of all points x divided by the number of points, i.e., rzx = sum(rx) / rnum; the first centroid y = the sum of all points y divided by the number of points, i.e., rzy = sum(ry) / rnum; the second set of data is (bx, by), with a count bnum, and the second centroid is:

[0097] The rear centroid x = the sum of all points x divided by the number of points, i.e., bzx = sum(bx) / bnum; the rear centroid y = the sum of all points y divided by the number of points, i.e., bzy = sum(by) / bnum;

[0098] e, calculate the slope angle;

[0099] The slope angle of the reflective strip in the lidar coordinate system, such as... Figure 3 As shown, the slope angle is calculated by taking the x and y differences between the front and rear centroids, finding the slope, and then finding the arctangent of the slope.

[0100] yaw = atan2((rzy-bzy),(rzx-bzx)); the front laser calibration angle in radians is ryaw = yaw (>0); the rear laser calibration angle in radians is byaw = yaw – M_PI (<0); these are the angles of the front and rear laser radars in the central coordinate system.

[0101] In one embodiment, calibrating the x and y coordinates of the mounting poses of the front and rear lidars within the central coordinate system, using the central coordinate system as a reference, includes the following steps:

[0102] The scanning data of the front lidar and the scanning data of the rear lidar are converted from polar coordinates to Cartesian coordinates (x, y).

[0103] Calculate the anterior centroid and the rear centroid;

[0104] The x-axis and y-axis coordinates of the front centroid and the rear centroid are summed and their average absolute values ​​are taken to obtain (cfx, cfy) and (cbx, cby), where cfx is the average absolute value of the x-axis of the front centroid, cfy is the average absolute value of the y-axis of the front centroid, cbx is the average absolute value of the x-axis of the rear centroid, and cby is the average absolute value of the y-axis of the rear centroid.

[0105] Projecting fx, fy, bx, and by into the central coordinate system yields ftx, fty, btx, and bty, where fx is the sum of the x-axis coordinates of the front and rear centroids of the front LiDAR scan data, fy is the sum of the y-axis coordinates of the front and rear centroids of the front LiDAR scan data, bx is the sum of the x-axis coordinates of the front and rear centroids of the rear LiDAR scan data, and by is the sum of the y-axis coordinates of the front and rear centroids of the rear LiDAR scan data.

[0106] According to the formulas tx=x*cos(yaw)+y*sin(yaw) and ty=y*cos(yaw)-x*sin(yaw), calculate the projected distance values ​​of the front lidar and the rear lidar in the x-axis and y-axis directions of the central coordinate system, where tx is the projected distance value in the x-axis direction and ty is the projected distance value in the y-axis direction.

[0107] According to the formula: x-axis calibration value of the front lidar = cfx – ftx;

[0108] The y-axis calibration value of the front lidar is cfy – fty;

[0109] The x-axis calibration value of the rear lidar is -(cbx-btx);

[0110] The y-axis calibration value of the rear lidar is -(cby-bty);

[0111] Calculate the calibration values ​​of the front lidar and the rear lidar in the x-axis and y-axis directions;

[0112] The calibration values ​​of the front and rear lidars in the x and y axes are stored in the indoor delivery robot registration file.

[0113] The calibration of the x and y coordinates of the installation poses of the front and rear lidars within the central coordinate system, using the central coordinate system as a reference, includes the following steps:

[0114] (1) Calculate the range values ​​in the x and y directions before and after the central radar:

[0115] A. Convert the polar coordinate point sets cfscan and cbscan to rectangular coordinate system points cfdata and cbdata;

[0116] B. Find the centroids of cfdata and cbdata before and after, based on the principle of 4(3)c above;

[0117] C. Sum the x and y values ​​of the front and rear centroids and take the average absolute value (which is the center point of the reflective strip), which are cfx, cfy, cbx, and cby.

[0118] (2) Calculate the projected distance values ​​of the front and rear lidars in the x and y directions of the central coordinate system:

[0119] A. Sum the x and y values ​​of the centroids before and after the right-angle point of fscan and take the average absolute value (which is the center point of the reflective strip), which is fx and fy;

[0120] B. Sum the x and y values ​​of the centroids before and after the right-angle point of bscan and take the average absolute value (which is the center point of the reflective strip), which is bx,by;

[0121] C. Project fx, fy, bx, by into the central coordinate system as ftx, fty, btx, bty;

[0122] In actual calibration, the x and y values ​​of the front and rear lidars relative to the central coordinate system are used. The calculation of the center points of the front and rear reflective strips by the front and rear lidars is completed within their respective coordinate systems. Therefore, the coordinate systems of the front and rear lidars need to be rotated until they are aligned with the x and y axes of the central coordinate system (e.g., ...). Figure 2 Therefore, by performing a coordinate transformation on the center point of the reflective strip measured by the front and rear lidars, we can obtain the distance from the center point of the reflective strip to the front and rear lidars in the x and y directions, assuming that the x and y axes of the front and rear lidar coordinate systems and the center coordinate system are consistent.

[0123] Projection formula: x value = x of the center point of the reflector multiplied by the cosine of the slope angle + y of the center point of the reflector multiplied by the sine of the slope angle, that is, tx = x*cos(yaw) + y*sin(yaw);

[0124] The y-value is calculated as: y = y at the center of the reflector multiplied by the cosine of the slope angle - x at the center of the reflector multiplied by the sine of the slope angle, i.e., ty = y * cos(yaw) - x * sin(yaw).

[0125] (3) Calculate the x, y calibration values ​​for the front and rear lidars:

[0126] Front LiDAR: The distance in the x and y directions relative to the center point of the robot = the distance in the x and y directions of the center point of the reflective strip identified by the central radar, minus the distance in the x and y directions of the center point of the reflective strip identified by the front LiDAR after projection (projection principle as above (2)c); that is, x = cfx – ftx, y = cfy – fty;

[0127] Rear LiDAR: The distance in the x and y directions relative to the center point of the robot = the distance in the x and y directions of the center point of the reflective strip after the central radar is identified, minus the distance in the x and y directions of the center point of the reflective strip after the rear LiDAR is identified (projection principle is as above (2)c); that is, x = -(cbx-btx), y = -(cby-bty);

[0128] For information on positive and negative deviations, please refer to [link / reference]. Figure 2 As shown.

[0129] In the above embodiments, by pre-setting a calibration scenario and using a central radar, front lidar, and rear lidar to scan the same marker within that scenario, the coordinate deviation between the front and rear lidars can be automatically calculated through coordinate transformation and centroid calculation, yielding the corresponding x, y, and yaw calibration parameters. This calibration method can automatically generate calibration parameters based on the structure of each delivery robot and the installation deviation of the lidars, enabling calibration of the installation position of the dual lidars on the delivery robot and significantly improving calibration efficiency and accuracy.

[0130] like Figure 6 As shown, in another embodiment, an indoor delivery robot lidar calibration device 600 is provided. The indoor delivery robot includes a front lidar and a rear lidar, which are diagonally arranged on the chassis of the indoor delivery robot; including:

[0131] The preset module 610 is used to preset a calibration scene, which includes preset a front plate and a rear plate that are parallel to each other, and the middle part of the front plate and the rear plate are respectively affixed with markers; the chassis is placed in the calibration scene, and the central radar used for calibration is placed in the center of the chassis, and the central radar is a 360-degree lidar.

[0132] The scanning module 620 is used to establish coordinate systems for the front lidar, the rear lidar and the central lidar respectively, and to scan the marker through the front lidar, the rear lidar and the central lidar respectively, wherein the coordinate system of the central lidar is the central coordinate system;

[0133] The calculation module 630 is used to convert the scanning data of the front lidar and the scanning data of the rear lidar from the polar coordinate system into a rectangular coordinate system point (x,y).

[0134] Divide the Cartesian coordinate system points of the front and rear lidars into two groups of data with the center of the chassis as the boundary, and calculate the centroids of the front and rear groups of data respectively. The centroid of the front group of data is the front centroid, and the centroid of the rear group of data is the rear centroid.

[0135] Using the central coordinate system as a reference, the slope angle yaw of the front lidar and the rear lidar is calibrated, where yaw = atan2((rzy-bzy),(rzx-bzx)), where rzy is the y-coordinate value of the front centroid, bzy is the y-coordinate value of the rear centroid, rzx is the x-coordinate value of the front centroid, and bzx is the x-coordinate value of the rear centroid.

[0136] Using the central coordinate system as a reference, the x and y coordinates of the installation poses of the front and rear lidars within the central coordinate system are calibrated.

[0137] In some embodiments, the marker is a reflective strip, and the marker is 0.4 meters to 0.8 meters long.

[0138] In some embodiments, when scanning the marker using the front lidar, the rear lidar, and the center lidar, the front lidar, the rear lidar, and the center lidar each scan the marker a preset number of times, and then the scan data are accumulated and averaged.

[0139] like Figure 7 As shown, in one embodiment, a computer-readable storage medium 700 is provided, on which a computer program is stored, which, when executed by a processor, performs the steps of the indoor delivery robot lidar calibration method as described in any of the above embodiments.

[0140] Finally, it should be noted that although the above embodiments have been described in the text and drawings of this application, this should not limit the scope of patent protection of this application. Any technical solutions that are based on the essential concept of this application and utilize the content described in the text and drawings of this application, resulting in equivalent structural or procedural substitutions or modifications, as well as the direct or indirect application of the technical solutions of the above embodiments to other related technical fields, are all included within the scope of patent protection of this application.

Claims

1. A method for calibrating a lidar sensor for an indoor delivery robot, characterized in that, The indoor delivery robot includes a front lidar and a rear lidar, which are diagonally mounted on the chassis of the indoor delivery robot; the calibration method includes the following steps: A preset calibration scenario includes a preset front panel and a rear panel that are parallel to each other, with markers affixed to the middle portions of the front panel and the rear panel respectively; The chassis is placed in the calibration scene in a predetermined direction, and the central radar used for calibration is placed in the center of the chassis. The central radar is a 360-degree lidar. Coordinate systems are established for the front lidar, the rear lidar, and the central lidar, respectively, and the marker is scanned by the front lidar, the rear lidar, and the central lidar, respectively, with the coordinate system of the central lidar being the central coordinate system; The scanning data of the front lidar and the scanning data of the rear lidar are converted from polar coordinates to Cartesian coordinates (x, y). Divide the Cartesian coordinate system points of the front and rear lidars into two groups of data with the center of the chassis as the boundary, and calculate the centroids of the front and rear groups of data respectively. The centroid of the front group of data is the front centroid, and the centroid of the rear group of data is the rear centroid. Using the central coordinate system as a reference, the slope angle yaw of the front lidar and the rear lidar is calibrated, where yaw = atan2((rzy - bzy),(rzx - bzx)), where rzy is the y-coordinate value of the front centroid, bzy is the y-coordinate value of the rear centroid, rzx is the x-coordinate value of the front centroid, and bzx is the x-coordinate value of the rear centroid. Using the central coordinate system as a reference, the x and y coordinates of the installation poses of the front and rear lidars within the central coordinate system are calibrated.

2. The lidar calibration method for indoor delivery robots according to claim 1, characterized in that, The calibration of the x and y coordinates of the installation pose of the front and rear lidars within the central coordinate system, using the central coordinate system as a reference, includes the following steps: The central radar identifies the reflective strips, captures laser data from -90° to 90°, selects the high-intensity portion of the data to identify the laser data corresponding to the front reflective strip, and saves the data as cfscan; it also captures laser data from 90° to 180° and -180° to -90°, selects the high-intensity portion of the data to identify the laser data corresponding to the rear reflective strip, and saves the data as cbscan; Calculate the x and y ranging values ​​of the central radar before and after: Convert the polar coordinate point sets cfscan and cbscan to rectangular coordinate points cfdata and cbdata; find the centroids of cfdata and cbdata before and after; sum the x and y values ​​of the centroids of the front and rear centroids and take the average absolute value, which are cfx, cfy, cbx, and cby; where cfx is the average absolute value of the front centroid along the x-axis, cfy is the average absolute value of the front centroid along the y-axis, cbx is the average absolute value of the rear centroid along the x-axis, and cby is the average absolute value of the rear centroid along the y-axis. Projecting fx, fy, bx, and by into the central coordinate system yields ftx, fty, btx, and bty, where fx is the sum of the x-axis coordinates of the front and rear centroids of the front LiDAR scan data, fy is the sum of the y-axis coordinates of the front and rear centroids of the front LiDAR scan data, bx is the sum of the x-axis coordinates of the front and rear centroids of the rear LiDAR scan data, and by is the sum of the y-axis coordinates of the front and rear centroids of the rear LiDAR scan data. According to the formulas tx = x*cos(yaw)+y*sin(yaw) and ty = y*cos(yaw)-x*sin(yaw), the projected distance values ​​of the front lidar and the rear lidar in the x-axis and y-axis directions of the central coordinate system are calculated, where tx is the projected distance value in the x-axis direction and ty is the projected distance value in the y-axis direction. According to the formula: x-axis calibration value of the front lidar = cfx – ftx; The y-axis calibration value of the front lidar = cfy – fty; The x-axis calibration value of the rear lidar = -(cbx - btx); The y-axis calibration value of the rear lidar = -(cby - bty); Calculate the calibration values ​​of the front lidar and the rear lidar in the x-axis and y-axis directions; The calibration values ​​of the front and rear lidars in the x and y axes are stored in the indoor delivery robot registration file.

3. The lidar calibration method for indoor delivery robots according to claim 2, characterized in that, The step of projecting fx, fy, bx, by onto the central coordinate system to obtain ftx, fty, btx, and bty includes the following steps: The coordinate systems of the front and rear lidars are rotated so that their x and y axes are aligned with the central coordinate system.

4. The lidar calibration method for indoor delivery robots according to claim 1, characterized in that, When scanning the marker using the front lidar, the rear lidar, and the center lidar, the front lidar, the rear lidar, and the center lidar each scan the marker a preset number of times, and then the scan data are accumulated and averaged.

5. The laser radar calibration method for indoor delivery robots according to claim 1, characterized in that, When scanning the marker using the front lidar, the rear lidar, and the central lidar, the front lidar captures laser data from -180° to 90° and retains the high-intensity portion of the data; the central lidar captures laser data from -90° to 90° and retains the high-intensity portion of the data as CFSCAN; the central lidar captures laser data from 90° to 180° and from -180° to -90° and retains the high-intensity portion of the data as CBSCCAN; the rear lidar captures laser data from -180° to 90° and retains the high-intensity portion of the data.

6. The laser radar calibration method for indoor delivery robots according to claim 1, characterized in that, The sign is a reflective strip, and the length of the sign is 0.4 meters to 0.8 meters.

7. A lidar calibration device for an indoor delivery robot, characterized in that, The indoor delivery robot includes a front lidar and a rear lidar, which are diagonally mounted on the chassis of the indoor delivery robot; including: The preset module is used to preset the calibration scene, including preset front and rear panels that are parallel to each other, with markers affixed to the middle parts of the front and rear panels respectively; the chassis is placed in the calibration scene, and the central radar used for calibration is placed in the center of the chassis, the central radar being a 360-degree lidar. The scanning module is used to establish coordinate systems for the front lidar, the rear lidar, and the central lidar respectively, and to scan the marker through the front lidar, the rear lidar, and the central lidar respectively, wherein the coordinate system of the central lidar is the central coordinate system; The calculation module is used to convert the scanning data of the front lidar and the scanning data of the rear lidar from the polar coordinate system to the rectangular coordinate system points (x, y); Divide the Cartesian coordinate system points of the front and rear lidars into two groups of data with the center of the chassis as the boundary, and calculate the centroids of the front and rear groups of data respectively. The centroid of the front group of data is the front centroid, and the centroid of the rear group of data is the rear centroid. Using the central coordinate system as a reference, the slope angle yaw of the front lidar and the rear lidar is calibrated, where yaw = atan2((rzy - bzy),(rzx - bzx)), where rzy is the y-coordinate value of the front centroid, bzy is the y-coordinate value of the rear centroid, rzx is the x-coordinate value of the front centroid, and bzx is the x-coordinate value of the rear centroid. Using the central coordinate system as a reference, the x and y coordinates of the installation poses of the front and rear lidars within the central coordinate system are calibrated.

8. The lidar calibration device for indoor delivery robots according to claim 7, characterized in that, The sign is a reflective strip, and the length of the sign is 0.4 meters to 0.8 meters.

9. The lidar calibration device for indoor delivery robots according to claim 7, characterized in that, When scanning the marker using the front lidar, the rear lidar, and the center lidar, the front lidar, the rear lidar, and the center lidar each scan the marker a preset number of times, and then the scan data are accumulated and averaged.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, performs the steps of the lidar calibration method for indoor delivery robots as described in any one of claims 1 to 6.

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