A wheel diameter measurement method based on single-line laser radar

Abstract

The application discloses a wheel diameter measurement method based on single-line laser radar and belongs to the technical field of wheel detection. The method is characterized in that two single-line laser radars are fixed above and below a wheel and can scan the side profile of the wheel and the scanned profiles are parallel. After the single-line laser radars scan the tooth profile of the wheel, the point cloud data collected by the single-line laser radars are acquired, and the coordinate data of the scanned wheel profile points are obtained through coordinate transformation and filtering. The two boundary point coordinates of the wheel profile scanned by the two single-line laser radars are extracted respectively. The length of the wheel profile scanned by the two single-line laser radars is calculated according to the two boundary point coordinates of the wheel profile, and the diameter of the wheel can be calculated according to the height difference between the two single-line laser radars and the length of the wheel profile scanned by the two single-line laser radars. The application has the advantages of fast measurement speed, high precision, strong applicability, and small influence of installation error on measurement precision.

Description

Technical Field

[0001] This invention relates to a method for measuring wheel diameter based on a single-line lidar, belonging to the field of wheel inspection technology. Background Technology

[0002] With the continuous development of intelligent transportation, the key dimensions of motor vehicle wheels directly affect vehicle driving safety. In order to avoid wheel wear caused by rolling contact friction between the wheel and the ground or track, resulting in wheels with excessive dimensions continuing to be used, it is necessary to dynamically and accurately measure the wheel diameter.

[0003] Currently, commonly used methods for measuring wheel diameter include dimensional measurement, laser rangefinder measurement, encoder measurement, and visual measurement. Dimensional measurement involves directly measuring the wheel diameter with a ruler or measuring tool; it is often used for temporary measurements but is prone to significant errors. Laser rangefinder measurement uses a laser rangefinder to measure the wheel diameter; however, it requires careful calibration to ensure accuracy and may introduce measurement errors on complex wheel surfaces. Encoder measurement involves mounting an encoder on the wheel and measuring the diameter by calculating wheel rotation; this requires mounting the encoder on the wheel, potentially increasing wheel load and complexity. Visual measurement uses a camera or other visual sensor to capture images of the wheel and then uses image processing algorithms to measure the wheel diameter. This method is highly dependent on the condition of the wheel surface and can be affected by factors such as lighting and reflection. Summary of the Invention

[0004] The purpose of this invention is to provide a wheel diameter measurement method based on single-line lidar, which can improve the measurement speed and accuracy of wheel diameter under non-demanding installation conditions.

[0005] The objective of this invention is achieved through the following technical solution.

[0006] This invention discloses a method for measuring wheel diameter based on a single-line lidar, comprising the following steps:

[0007] Step 1: Fix two single-line lidars vertically around the wheel detection line in a vertical plane according to the actual working conditions. It is not necessary to strictly ensure that the vertical positions of the two single-line lidars are exactly the same. Just ensure that the two single-line lidars can scan the side profile of the wheel when the wheel passes by and that the scanned profiles are parallel. Record the vertical height difference as h.

[0008] Step 2: After the single-line lidar scans the wheel tooth profile, it acquires the point cloud data it collects, and performs coordinate transformation from polar coordinate system to Cartesian coordinate system and Kalman filter preprocessing on the collected data to obtain the coordinate data of each point of the wheel profile scanned by the two single-line lidars, thus realizing data acquisition.

[0009] Step 3: Extract the coordinates of the two boundary points of the wheel contour scanned by the two single-line LiDARs respectively. That is, the coordinates of the two boundary points of the upper single-line LiDAR are (X... mh ,Y mh ) and (X nh ,Y nh The coordinates of the two boundary points of the lower single-line lidar are (X... ml ,Y ml ) and (X nl ,Y nl This means that data extraction is achieved.

[0010] Step 4: Based on the height difference h between the two single-line lidars, the length of the contour scanned by the upper single-line lidar... Designated as 2a, the length of the contour scanned by the lower single-line lidar. Let it be denoted as 2b. The diameter of the wheel can be calculated using the Pythagorean theorem based on the following relationship.

[0011] The diameter of the wheel can be calculated using the Pythagorean theorem and the following specific method:

[0012] When the two profile lines are located on the same side of the wheel's axis of symmetry, which is parallel to them:

[0013] When the two contour lines are located on opposite sides of the wheel's axis of symmetry, which is parallel to the wheel:

[0014] Where R is the radius of the wheel, and l is the distance between the profile length scanned by the upper single-line lidar and the parallel axis of symmetry of the wheel.

[0015] The formula for calculating the diameter is:

[0016] The diameter D of the wheel is calculated based on the diameter calculation formula, that is, the wheel diameter is measured based on a single-line lidar.

[0017] Beneficial effects:

[0018] 1. The present invention discloses a wheel diameter measurement method based on single-line lidar. The wheel diameter can be obtained by scanning any side profile of the wheel with two single-line lidars. The detection device of this method has a simple structure, low manufacturing cost, fast measurement speed, high accuracy, and strong applicability. It can be applied to the wheel diameter measurement of EMU trains, locomotives, freight cars, subways and other special vehicles.

[0019] 2. The present invention discloses a wheel diameter measurement method based on single-line lidar. Two single-line lidars are installed one above the other to measure the wheel diameter. The installation process only requires that both single-line lidars can scan the side profile of the wheel and that the profiles are parallel. No strict installation conditions or wheel stopping position are required, and the measurement accuracy is less affected by installation errors, thus having high reliability. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall process of a wheel diameter measurement method based on single-line lidar proposed in this invention;

[0021] Figure 2 This is a front view of the measurement scene of the first embodiment of the wheel diameter measurement method based on single-line lidar proposed in this invention;

[0022] Figure 3 This is a side view of the measurement scene of the first embodiment of the wheel diameter measurement method based on single-line lidar proposed in this invention;

[0023] Figure 4 This is a front view of the measurement scene of the second embodiment of the wheel diameter measurement method based on single-line lidar proposed in this invention;

[0024] Figure 5 This is a side view of the measurement scenario of a second embodiment of a wheel diameter measurement method based on a single-line lidar proposed in this invention;

[0025] Figure 6 This is a top view of the measurement scenario of the third embodiment of the wheel diameter measurement method based on single-line lidar proposed in this invention;

[0026] Figure 7 This is a side view of the measurement scenario of the third embodiment of the wheel diameter measurement method based on single-line lidar proposed in this invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0028] Implementation Method 1

[0029] like Figures 1-3 As shown in the figure, this embodiment discloses a method for measuring wheel diameter based on single-line lidar, and the specific implementation steps are as follows:

[0030] S1: Fix two single-line lidars vertically according to the actual working conditions. The two contour lines scanned by the two single-line lidars are located on the same side of the wheel's axis of symmetry, which is parallel to the wheel. The two line lidars are installed in the same position in the Y direction. At the same time, the side contour of the wheel at the stopping position during wheel detection is parallel to the installation plane of the two line lidars. Record the installation height difference as h.

[0031] S2: After the single-line lidar scans the wheel tooth profile, it acquires the point cloud data it collects, and performs coordinate transformation from polar coordinate system to Cartesian coordinate system and Kalman filter preprocessing on the collected data to obtain the coordinate data of each point of the wheel profile scanned by the two single-line lidars.

[0032] S3: Extract the coordinates of the two boundary points of the wheel contour scanned by the single-line LiDAR, that is, the coordinates of the two boundary points of the upper single-line LiDAR are (X... mh ,Y mh ) and (X nh ,Y nh The coordinates of the two boundary points of the lower single-line lidar are (X... ml ,Y ml ) and (X nl ,Y nl ).

[0033] S4: Based on the installation positions of the two linear lidars in S1, X can be determined. mh =X nh =X ml =X nl The length of the contour scanned by the upper single-line lidar Noted as 2a; the length of the contour scanned by the lower single-line lidar. Let it be 2b. According to the Pythagorean theorem, we have:

[0034]

[0035] Where R is the radius of the wheel, and l is the distance between the profile length scanned by the upper single-line lidar and the parallel axis of symmetry of the wheel.

[0036] Furthermore, its diameter can be determined as follows: Implementation Method 2

[0037] like Figure 1 , Figures 4-5 As shown in the figure, this embodiment discloses a method for measuring wheel diameter based on single-line lidar, and the specific implementation steps are as follows:

[0038] S1: Fix two single-line lidars vertically according to the actual working conditions. The two contour lines scanned by the two single-line lidars are located on both sides of the wheel's axis of symmetry, which is parallel to the wheel. The installation positions of the two lidars in the Y direction are not the same. Ensure that the side contour of the wheel at the stopping position during wheel detection is parallel to the installation plane of the two lidars. Record the installation height difference as h.

[0039] S2: Same as S2 in Implementation Method 1;

[0040] S3: Same as S3 in Implementation Method 1;

[0041] S4: Based on the installation positions of the two linear lidars in S1, X can be determined. mh =X nh =X ml =X nl The length of the contour scanned by the upper single-line lidar Noted as 2a; the length of the contour scanned by the lower single-line lidar. Let it be 2b. According to the Pythagorean theorem, we have:

[0042]

[0043] Where R is the radius of the wheel, and l is the distance between the profile length scanned by the upper single-line lidar and the parallel axis of symmetry of the wheel.

[0044] Furthermore, its diameter can be determined as follows: Implementation Method 3

[0045] like Figure 1 , 6 As shown in Figure 7, the specific implementation steps of the wheel diameter measurement method based on single-line lidar disclosed in this embodiment are as follows:

[0046] S1: Fix two single-line lidars vertically according to the actual working conditions. The two contour lines scanned by the two single-line lidars are located on the same side of the wheel's axis of symmetry, which is parallel to the wheel. The two line lidars are installed in the same position in the Y direction. When the wheel is detected, there is a certain angle between the side contour of the wheel at the stopping position and the installation plane of the two line lidars. Record the installation height difference as h.

[0047] S2: Same as S2 in Implementation Method 1;

[0048] S3: Same as S3 in Implementation Method 1;

[0049] S4: Based on the installation positions of the two line lidars in S1, the upper single-line lidar scans the contour length. Noted as 2a; the length of the contour scanned by the lower single-line lidar. Let it be 2b. According to the Pythagorean theorem, we have:

[0050]

[0051] Where R is the radius of the wheel, and l is the distance between the profile length scanned by the upper single-line lidar and the parallel axis of symmetry of the wheel.

[0052] The diameter is further obtained as:

[0053] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A method for measuring wheel diameter based on single-line lidar, characterized in that: Includes the following steps, Step 1: Fix two single-line lidars vertically around the wheel detection line in the vertical plane according to the actual working conditions. It is not necessary to strictly ensure that the vertical positions of the two single-line lidars are exactly the same. Just ensure that the two single-line lidars can scan the side profile of the wheel when the wheel passes by and that the scanned profiles are parallel. Record the vertical height difference as h. Step 2: After the single-line lidar scans the wheel tooth profile, it acquires the point cloud data it collects, and performs coordinate transformation from polar coordinate system to Cartesian coordinate system and Kalman filter preprocessing on the collected data to obtain the coordinate data of each point of the wheel profile scanned by the two single-line lidars, thus realizing data acquisition. Step 3: Extract the coordinates of the two boundary points of the wheel contour scanned by the two single-line LiDARs respectively. That is, the coordinates of the two boundary points of the upper single-line LiDAR are as follows: and The coordinates of the two boundary points of the lower single-line lidar are respectively and This means achieving data extraction; Step 4: Based on the height difference h between the two single-line lidars, the length of the contour scanned by the upper single-line lidar... denoted as 2a, the length of the contour scanned by the lower single-line lidar. Let 2b be the diameter of the wheel. According to the Pythagorean theorem, the following relationship is obtained to calculate the diameter of the wheel, that is, the wheel diameter is measured based on a single-line lidar. The diameter of the wheel can be calculated using the Pythagorean theorem and the following specific method: When the two profile lines are located on the same side of the wheel's axis of symmetry, which is parallel to them: ; When the two contour lines are located on opposite sides of the wheel's axis of symmetry, which is parallel to the wheel: ; Where: R is the radius of the wheel, and l is the distance from the outline length scanned by the upper single-line lidar to the parallel axis of symmetry of the wheel. The formula for calculating the diameter is: ; The diameter D of the wheel is calculated based on the diameter calculation formula, that is, the wheel diameter is measured based on a single-line lidar.

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