An object outline dimension measurement device based on lidar and its measurement method

Abstract

The present invention belongs to the technical field of object contour measurement, and specifically relates to an object outer contour size measurement device based on lidar and its measurement method, including: a column, on the upper end of the side wall of the column, a rotary drive mechanism is installed, and a lidar measuring instrument is connected to the output shaft of the rotary drive mechanism; a handheld handle, a bearing is sleeved on the outer wall of the column, and the handheld handle is connected to the outer wall of the bearing through a support rod. The handheld lidar can quickly and accurately collect the point cloud data of the object to be measured, and has the advantages of high-resolution acquisition, high precision, and strong anti-interference ability. Using a handheld 3D laser scanner to collect the point cloud of the object to be measured and developing an intelligent method for obtaining the object size will greatly improve the efficiency, that is, ensure the personal safety of on-site surveying and mapping personnel, reduce the labor efficiency, and improve the operation efficiency. The three-dimensional contour of the object to be measured is intelligently drawn. The measurement is accurate and fast. It reduces the labor intensity and improves the work efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of object contour measurement, and specifically relates to an object outline dimension measurement device based on lidar and a measurement method thereof. Background Art

[0002] With the rapid development of the economy, the volume of freight transported by rail and road has increased sharply. Obtaining the external dimensions of the transported goods before transportation can obtain an accurate installation and reinforcement plan and improve transportation safety.

[0003] Currently, for object contour measurement, a lidar measuring instrument is mostly fixedly installed directly above the measurement object, which can only measure small-sized objects, has a narrow application scenario, and converting point cloud data into an image to obtain the object size will cause a certain loss of accuracy.

[0004] There is also a dynamic measurement method for vehicle outline dimensions based on lidar point cloud. This method measures the length, width, and height of a vehicle by fixedly installing 3 lidars and moving the vehicle. In this method, the vehicle must travel along a specified straight line. Summary of the Invention

[0005] The purpose of the present invention is to provide an object outline dimension measurement device based on lidar and a measurement method thereof, so as to solve the problems raised in the above background art that currently, for object contour measurement, a lidar measuring instrument is mostly fixedly installed directly above the measurement object, which can only measure small-sized objects, has a narrow application scenario, and converting point cloud data into an image to obtain the object size will cause a certain loss of accuracy. There is also a dynamic measurement method for vehicle outline dimensions based on lidar point cloud. This method measures the length, width, and height of a vehicle by fixedly installing 3 lidars and moving the vehicle. In this method, the vehicle must travel along a specified straight line.

[0006] To achieve the above purpose, the present invention provides the following technical solution: An object outline dimension measurement device based on lidar, comprising:

[0007] A column, on the upper end of the side wall of the column, a rotary drive mechanism is installed, and a lidar measuring instrument is connected to the output shaft of the rotary drive mechanism;

[0008] A hand-held handle, a bearing is sleeved on the outer wall of the column, the hand-held handle is connected to the outer wall of the bearing through a support rod, and the hand-held handle rotates relative to the column through the bearing.

[0009] Preferably, a support plate is provided on the lower side of the outer wall of the column, and the support plate is used to support on the user's waist.

[0010] Preferably, the support plate is arc-shaped and the support plate is made of rubber material.

[0011] Preferably, a hanging rope is provided on the upper side of the outer wall of the column. The hanging rope is a hanging rope made of elastic material and is used to be put around the user's neck.

[0012] Preferably, the rotation driving mechanism is a driving motor. The handheld handle is a hollow elliptical ring, and a hand-held cross bar is fixedly connected inside the handheld handle.

[0013] A method for measuring the outer contour dimensions of an object based on lidar. This method for measuring the outer contour dimensions of an object based on lidar is based on a device for measuring the outer contour dimensions of an object based on lidar. The specific steps of this method for measuring the outer contour dimensions of an object based on lidar are as follows:

[0014] S1: Obtain a three-dimensional point cloud containing the object to be measured based on a lidar measuring instrument;

[0015] S2: Hold the lidar measuring instrument and move it around the object to be measured for one week to obtain a three-dimensional point cloud and record the movement trajectory of the lidar measuring instrument;

[0016] S3: Extract the three-dimensional point cloud of the object to be measured based on the movement trajectory;

[0017] S4: Obtain a closed polygon based on the movement trajectory obtained by the lidar measuring instrument. Traverse all the three-dimensional point clouds. If a point is inside the polygon, retain the point;

[0018] S5: Based on the ground filtering method, separate the ground points G and the point cloud O of the object to be measured;

[0019] S6: Fit the plane normal V using the ground point cloud G;

[0020] S7: Calculate the rotation matrix R1 to make the normal V parallel to the Z-axis (0, 0, 1), R1*V / / Z;

[0021] S8: Rotate the point cloud O to obtain the point cloud M, M = R1*O;

[0022] S9: Cut off the point cloud A of the protruding part in the point cloud M and retain the main body point cloud B;

[0023] S10: Project the point cloud B onto the XOY plane to obtain a two-dimensional point cloud C;

[0024] S11: Calculate the minimum circumscribed rectangle of the point cloud C and record the length, width, and main axis direction;

[0025] S12: Calculate the rotation matrix R2 to make the main axis direction parallel to the X-axis direction;

[0026] S13: Rotate the point cloud M using the rotation matrix R2 to obtain the point cloud K, K = R2*M;

[0027] S14: At this time, the minimum circumscribed cuboid of the point cloud K is parallel to the X, Y, and Z axes;

[0028] S15: Project the point cloud K onto the XOZ and YOZ planes respectively to obtain two-dimensional point clouds KX and KY;

[0029] S16: Calculate the boundary points of the two-dimensional point clouds KX and KY respectively, and connect these boundary points to obtain the contour of the object.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] The handheld lidar can quickly and accurately collect the point cloud data of the object to be measured, and has the advantages of high-resolution acquisition, high precision, and strong anti-interference ability. Using a handheld 3D laser scanner to collect the point cloud of the object to be measured and developing an intelligent method for obtaining the object size will greatly improve the efficiency, that is, ensure the personal safety of on-site surveying and mapping personnel, reduce labor efficiency, and improve operation efficiency.

[0032] A method for measuring the outer contour size of an object based on lidar is provided. Based on a handheld 3D laser scanner, the point cloud of the object to be measured in any scene is quickly obtained, and the three-dimensional contour of the object to be measured is intelligently drawn. The measurement is accurate and fast. It reduces labor intensity and improves work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic structural diagram of the present invention when the handheld handle is not used and rotated to the right;

[0034] Figure 2 It is a schematic structural diagram of the present invention when the handheld handle is located on the left when in use;

[0035] Figure 3 It is a schematic structural diagram of the lidar measuring instrument rotating around the object to be measured for one week;

[0036] Figure 4 It is a state diagram of a process for extracting the three-dimensional point cloud of the object to be measured;

[0037] Figure 5 It is another state diagram of a process for extracting the three-dimensional point cloud of the object to be measured;

[0038] Figure 6 It is a closed polygon diagram formed on the side of the object to be measured;

[0039] Figure 7 It is a closed polygon diagram formed on the front of the object to be measured;

[0040] Figure 8 It is a side contour diagram of the object obtained by connecting these boundary points;

[0041] Figure 9To connect these boundary points to obtain the front contour diagram of the object.

[0042] In the figure: 1, column; 2, rotary drive mechanism; 3, lidar measuring instrument; 4, support plate; 5, hanging rope; 6, bearing; 7, hand-held handle. Specific embodiments

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0044] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0045] Embodiment:

[0046] Please refer to Figure 1-2 , the present invention provides a technical solution: an object outer contour dimension measuring device based on lidar, including:

[0047] Column 1, a rotary drive mechanism 2 is installed at the upper end of the side wall of the column 1, and a lidar measuring instrument 3 is connected to the output shaft of the rotary drive mechanism 2;

[0048] Hand-held handle 7, a bearing 6 is sleeved on the outer wall of the column 1, the hand-held handle 7 is connected to the outer wall of the bearing 6 through a support rod, and the hand-held handle 7 rotates relative to the column 1 through the bearing 6.

[0049] When in use, hold the hand-held handle 7, lift the column 1, the rotary drive mechanism 2, and the lidar measuring instrument 3 through the hand-held handle 7, so that the lidar measuring instrument 3 can collect the contour of the object to be measured. As the measurement personnel hold and collect, walk around the object to be measured for one circle to collect the object to be measured, and the rotary drive mechanism 2 can drive the lidar measuring instrument 3 to rotate to expand the collection range.

[0050] A support plate 4 is provided on the lower side of the outer wall of the column 1, and the support plate 4 is used to support the user's waist. The support plate 4 is arranged in an arc shape and is made of rubber material. A hanging rope 5 is provided on the upper side of the outer wall of the column 1. The hanging rope 5 is an elastic hanging rope and is used to be put around the user's neck. The rotation driving mechanism 2 is a driving motor. The hand-held handle 7 is a hollow elliptical ring, and a hand-held cross bar is fixedly connected inside the hand-held handle 7.

[0051] During use, the support plate 4 supports the user's waist and abdomen, and the hanging rope 5 is hung around the user's neck, so that the column 1, the rotation driving mechanism 2, and the lidar measuring instrument 3 are integrally hung on the user's body.

[0052] A method for measuring the external contour dimensions of an object based on lidar. This method for measuring the external contour dimensions of an object based on lidar is based on a device for measuring the external contour dimensions of an object based on lidar. The specific steps of this method for measuring the external contour dimensions of an object based on lidar are as follows:

[0053] A hand-held 3D laser scanner is a portable 3D scanner that can obtain 3D data of the object surface by hand-held scanning, and has the advantages of flexibility, high efficiency, and ease of use.

[0054] S1: Extract the 3D point cloud of the object to be measured based on the measurement trajectory. According to the movement trajectory of the hand-held 3D laser scanner, form a polygon. Traverse each point in the 3D point cloud. If the point is inside the polygon, keep the point. Finally, form the point cloud of the object to be measured.

[0055] S2: Based on the ground filtering method, separate the ground points G and the point cloud O of the object to be measured

[0056] The point cloud filtering algorithm involved can be any practical ground filtering algorithm. The ground filtering algorithm can distinguish between ground points and non-ground points. The point cloud of the object to be measured is among the non-ground points.

[0057] S3: Use the ground point cloud G to fit the plane normal V

[0058] Use the plane fitting method based on RANSAC. The RANSAC fitting plane randomly selects the minimum number of point clouds that can form a plane from the point cloud data, and uses these point clouds to calculate the parameters of the plane. By setting parameters, record the number of point clouds that meet the plane parameters in all point clouds, and repeat multiple times until the plane parameters that satisfy the maximum number of point clouds are output.

[0059] S4: Calculate the rotation matrix R1 to make the normal V parallel to the Z axis (0, 0, 1), R1*V / / Z

[0060] Let V = [a, b, c], first rotate counterclockwise by α around the Z axis, and the rotation matrix is RZ

[0061]

[0062] Rotate counterclockwise about the Y axis by β, and the rotation matrix is R Y

[0063]

[0064] The final rotation matrix R1 is

[0065] R1 = R Y R Z

[0066] S5: Rotate the point cloud O to obtain the point cloud M, M = R1 * O

[0067] S6: Crop the point cloud A of the protruding part in the point cloud M (such as the rearview mirror of a vehicle), and retain the main body point cloud B

[0068] The protruding part of the object will affect the positioning of the main axis of the object. Therefore, this part of the point cloud is cropped first, and the minimum bounding rectangle of the main body point cloud of the object is retained.

[0069] S7: Project the point cloud B onto the XOY plane to obtain the two-dimensional point cloud C

[0070] After passing through the rotation matrix R1, retaining the X and Y coordinates of the point cloud M is the point cloud coordinate after projecting onto the XOY plane, and the two-dimensional point cloud C is obtained

[0071] S8: Calculate the minimum bounding rectangle of the point cloud C, and record the length L, width W, and the main axis direction [k1, k2, 0]

[0072] S9: Calculate the rotation matrix R2 to make the main axis direction parallel to the X-axis direction

[0073] The main axis direction [k1, k2, 0], rotating counterclockwise about the Z axis by θ can be parallel to the X axis, and the rotation matrix is

[0074]

[0075] S10: Rotate the point cloud M using the rotation matrix R2 to obtain the point cloud K, K = R2 * M

[0076] S11: At this time, the minimum bounding cuboid of the point cloud K is parallel to the X, Y, and Z axes

[0077] S12: Project the point cloud K onto the XOZ and YOZ planes respectively to obtain the two-dimensional point clouds KX and KY

[0078] S13: Calculate the boundary points of the two-dimensional point clouds KX and KY respectively to obtain the contour of the object.

[0079] The two-dimensional point cloud boundary extraction algorithm involved can be any practical point cloud boundary algorithm, and the commonly used ones are Convexhull discrete point set method, Delaunay triangulation method and Alpha Shape method.

[0080] Taking the Alpha Shape method as an example, it is applicable to this situation. The AlphaShape algorithm is like setting a ball with a radius of alpha on the scattered points and rolling it, and the final line is the contour line.

[0081] S14: Connect the two-dimensional boundary points to obtain the outline of the object.

[0082] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the attached claims rather than the above description. Therefore, it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention, and any figure marks in the claims should not be regarded as limiting the claims involved.

[0083] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for measuring the external dimensions of an object based on lidar, characterized in that: The method for measuring the external dimension of an object based on lidar is implemented by a device for measuring the external dimension of an object based on lidar. Among them, the device for measuring the external dimension of an object based on lidar includes: a column (1) and a hand-held handle (7). A rotation driving mechanism (2) is installed at the upper end of the side wall of the column (1). A lidar measuring instrument (3) is connected to the output shaft of the rotation driving mechanism (2). A bearing (6) is sleeved on the outer wall of the column (1). The hand-held handle (7) is connected to the outer wall of the bearing (6) through a support rod. The hand-held handle (7) rotates relative to the column (1) through the bearing (6). A support plate (4) is arranged on the lower side of the outer wall of the column (1). The support plate (4) is used to support on the user's waist. The support plate (4) is arranged in an arc shape and is made of rubber material. A hanging rope (5) is arranged on the upper side of the outer wall of the column (1). The hanging rope (5) is a hanging rope made of elastic material and is used to be put on the user's neck. The rotation driving mechanism (2) is a driving motor. The hand-held handle (7) is a hollow elliptical ring, and a hand-held cross bar is fixedly connected inside the hand-held handle (7). The specific steps of the method for measuring the external dimension of an object based on lidar are as follows: S1: Obtain a three-dimensional point cloud containing the object to be measured based on the lidar measuring instrument (3). S2: Hold the lidar measuring instrument (3) and rotate it around the object to be measured for one week to obtain a three-dimensional point cloud, and record the moving trajectory of the lidar measuring instrument (3). S3: Extract the three-dimensional point cloud of the object to be measured based on the moving trajectory. S4: Obtain a closed polygon based on the moving trajectory obtained by the lidar measuring instrument (3). Traverse all three-dimensional point clouds. If the point is inside the polygon, retain the point. S5: Based on the ground filtering method, separate the ground points G and the point cloud O of the object to be measured. S6: Fit the plane normal V using the ground point cloud G. S7: Calculate the rotation matrix R1 to make the normal V parallel to the Z-axis (0, 0, 1), R1*V / / Z. S8: Rotate the point cloud O to obtain the point cloud M, M = R1*O. S9: Cut off the point cloud A of the protruding part in the point cloud M and retain the main body point cloud B. S10: Project the point cloud B onto the XOY plane to obtain a two-dimensional point cloud C. S11: Calculate the minimum circumscribed rectangle of the point cloud C and record the length, width and main axis direction. S12: Calculate the rotation matrix R2 to make the main axis direction parallel to the X-axis direction. S13: Rotate the point cloud M using the rotation matrix R2 to obtain the point cloud K, K = R2*M. S14: At this time, the minimum circumscribed cuboid of the point cloud K is parallel to the X, Y, and Z axes. S15: Project the point cloud K onto the XOZ and YOZ planes respectively to obtain two-dimensional point clouds KX and KY. S16: Calculate the boundary points of the two-dimensional point clouds KX and KY respectively, and connect these boundary points to obtain the contour of the object.

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