A method for determining the wheel center position of a vehicle tire

Abstract

The present invention discloses a method for determining the wheel center position of a vehicle tire. The method comprises the following steps: obtaining point cloud data of a tire through a three-dimensional laser scanning device system, and fitting and generating a rim outer section, a tire outer section and a tire inner section according to the vehicle tire point cloud in Catia software, and fitting and generating a tire center plane according to the tire outer section and the tire inner section; at the same time, fitting and generating a rim cross-section circle according to the rim outer section in Catia software, selecting the center of the rim cross-section circle, and projecting the center of the rim cross-section circle onto the tire center plane. After projection, the center contour of the rim cross-section circle is obtained on the tire center plane, and the point formed by the contour is the wheel center position of the vehicle tire.

Description

Technical Field

[0001] The invention relates to the technical field of automobile measurement, and in particular to a method for determining the wheel center position of a vehicle tire. Background Art

[0002] The wheel center position point is an important hard point for obtaining vehicle overall layout parameters such as vehicle static radius, wheelbase and track width. The existing methods for obtaining the tire wheel center position point on the market are mostly a mechanical device for fixing the tire, combined with a non-contact light source to obtain the shape of the tire. The method is to remove the tire from the whole vehicle and fix it. In this case, the standard tire pressure and the impact of the vehicle under load on the tire deformation cannot be calculated, so there will be a certain error in the measurement.

[0003] The invention patent with publication number CN112361968A discloses a vehicle wheel center measuring device and a measuring method. The patent designs a mechanical device including: a mounting base, a height adjustment structure, and a first laser pen, a second laser pen, an intermediate laser pen and a shifting structure installed on the mounting base to achieve the wheel center position. The patent requires a specially designed mechanical device for measuring the vehicle wheel center position. The mechanical device is complex in design and has a high design investment cost. At the same time, the method of obtaining the tire wheel center position point through the mechanical device is relatively complex. Summary of the invention

[0004] The object of the present invention is to provide a method for determining the wheel center position of a vehicle tire.

[0005] To achieve the above objectives, the technical solution of the present invention is:

[0006] A method for determining the wheel center position of a vehicle tire comprises the following steps: generating a rim outer section, a tire outer section and a tire inner section based on a vehicle tire point cloud, and generating a tire center plane based on the tire outer section and the tire inner section; generating a rim cross-section circle based on the rim outer section, selecting the center of the rim cross-section circle, projecting the center of the rim cross-section circle onto the tire center plane, obtaining a center contour of the rim cross-section circle on the tire center plane, and the point formed by the contour is the wheel center position of the vehicle tire.

[0007] Furthermore, the vehicle tire point cloud acquisition comprises the following steps:

[0008] ① Inflate / deflate the vehicle tires to the standard tire pressure on the nameplate, place the vehicle on level ground, load it to a ready state, and affix positioning marks on the outer side of the vehicle tires and the annular surface of the tires excluding the part that touches the ground;

[0009] ② A three-dimensional laser scanning device system connected to a computer scans the positioning points on the outer side of the vehicle tire and the annular surface of the tire, obtains the coordinate values ​​of the positioning points, and establishes a coordinate system of the positioning points;

[0010] ③ Remove the tire from the vehicle, and paste additional positioning marks on the part of the tread close to the inner side of the tire just above the annular surface of the tire, and on the outer surface of the inner side of the tire. The three-dimensional laser scanning equipment system sequentially and continuously scans the positioning marks on the outer side of the tire, the annular surface of the tire, and the inner side of the tire. The coordinate values ​​of the additionally pasted positioning marks are added to the coordinate system established in step ② to obtain a coordinate system including the coordinate values ​​of the positioning marks on the outer side of the tire, the inner side of the tire, and the annular surface of the tire;

[0011] ④ The three-dimensional laser scanning equipment system reads the coordinate values ​​of the positioning marks on the tire, scans the outer surface of the tire with the positioning marks, and obtains the tire point cloud.

[0012] Furthermore, the positioning marks are arranged at intervals on the outer surface of the tire, and the distance between every two positioning marks is 15 cm.

[0013] Furthermore, the method for obtaining the rim outer section is to import the tire point cloud data into the IMinspect module of the VXelements software, select the point cloud of the protruding part of the outer ring of the vehicle tire rim, use the command Create Plane-Fit-Fit to Unit-Maximum, calculate the fitting to generate the plane, and the plane is the tire rim outer section.

[0014] Furthermore, the plane features of the rim outer section are stored in an igs format file, and the igs format file and tire point cloud data are both imported into CATIA software.

[0015] Furthermore, the method for obtaining the outer section of the tire is, based on CATIA software, selecting the outer section of the rim generated by fitting, dragging the outer section of the rim generated by fitting to the outside of the tire point cloud, and obtaining the outer plane of the tire point cloud; using the command "Measure Distance" to obtain the distance between the tire point cloud and the outer plane of the tire point cloud; using the command "Translate", "Vector Definition" selects "Direction, Distance", the element selects the outer plane of the tire point cloud, the direction selects "zx plane", and the distance value is input as the distance between the tire point cloud and the outer plane 7 of the tire point cloud to generate the outer section of the tire.

[0016] Furthermore, the method for obtaining the inner section of the tire is, based on CATIA software, selecting the outer section of the rim generated by fitting, dragging the outer section of the rim generated by fitting to the inside of the tire point cloud, and obtaining the inner plane of the tire point cloud; using the command "Measure Distance" to obtain the distance between the tire point cloud and the inner plane of the tire point cloud; using the command "Translate", "Vector Definition" selects "Direction, Distance", the element selects the inner plane of the tire point cloud, the direction selects "zx plane", and the distance value is input as the distance between the tire point cloud and the inner plane of the tire point cloud to generate the inner section of the tire.

[0017] Furthermore, the method for obtaining the tire center plane is, based on CATIA software, clicking the command "Measure Distance" to obtain the distance W between the outer section of the tire and the inner section of the tire, where W is the tire width, clicking the command "Plane", the plane type "Offset Plane", the element selection of the outer section or the inner section, the direction is the Y direction, the offset distance is W / 2, and the generated plane is the tire center plane.

[0018] Furthermore, the method for obtaining the rim cross-section circle is, based on CATIA software, to select the rim outer section, adjust the position of the rim outer section until a rim edge circle is formed, click Apply and OK to generate a cross-section line of the rim edge, click the "Circle" command, select "Three Points" as the circle type, and generate a circle by fitting the three points selected on the rim edge cross-section line. The circle generated by fitting is the rim cross-section circle.

[0019] Furthermore, the center of the rim cross-section circle is projected onto the tire center plane, and the center contour of the rim cross-section circle is obtained on the tire center plane. The point formed by the contour is the wheel center position of the vehicle tire.

[0020] The beneficial effects of the present invention are:

[0021] 1. The present invention uses existing scanning equipment to scan tires under standard tire pressure and in a no-load state to obtain tire point clouds, and quickly and accurately locate the tire center position in the Catia software; it solves the problem that when determining the tire wheel center position, the wheel center position is difficult to determine due to the difficulty in defining the tire center plane at half the tire width.

[0022] 2. The present invention constructs a tire data model through laser scanning, and obtains the wheel center of the tire to be tested based on the tire data model in the software. Compared with the conventional method of determining the tire wheel center position by using a mechanical fixing device combined with a photoelectric scanning device, the method of the present invention for determining the tire wheel center position is simple and efficient, and the result is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The figure is a schematic diagram of pasting positioning marks on the outer side of the tire of the present invention.

[0024] Figure 2 It is a schematic diagram of pasting positioning marks on the inner side surface and the annular surface of the tire of the present invention.

[0025] Figure 3 The three-dimensional laser scanning device system of the present invention sequentially scans the positioning points on the outer side surface, the annular surface and the inner side surface of the tire.

[0026] Figure 4 It is a schematic diagram of the outer section of the fitting rim of the present invention.

[0027] Figure 5 It is a schematic diagram of the outer side section of the fitted tire of the present invention.

[0028] Figure 6 It is a schematic diagram of the inner side section of the fitted tire of the present invention.

[0029] Figure 7 It is a schematic diagram of the center plane of the tire fitted according to the present invention.

[0030] Figure 8 It is a schematic diagram of the cross-section circle of the fitting rim of the present invention.

[0031] In the figure: positioning mark 1; outer side of the tire 2; inner side of the tire 3; annular surface of the tire 4; protruding part of the outer ring of the rim 5; outer section of the rim 6; outer plane of the tire point cloud 7; outer section of the tire 8; inner plane of the tire point cloud 9; inner section of the tire 10; center plane of the tire 11; rim edge circle 12; rim cross-section circle 13. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the invention clearer, the present invention is further described below with reference to the accompanying drawings.

[0033] The present invention uses a three-dimensional laser scanning device system, which has the functions of both a photogrammetry positioning system and a three-dimensional laser scanner.

[0034] The point cloud in the present invention refers to a set of points generated by a large amount of point coordinate information collected by a 3D laser scanning device system by irradiating the surface of an object.

[0035] The positioning mark 1 is a special reflective point suitable for photogrammetry and scanning positioning that is matched with the three-dimensional laser scanning measurement system. It is generally a round sticker with an adhesive on the back, with a white circle in the middle and a black ring around it. In the present invention, the positioning mark 1 is pasted on the outer surface of the tire, and the distance between every two positioning marks 1 is about 15-20cm, and an interval of 15cm is a preferred implementation.

[0036] In the present invention, any tire of the vehicle can be selected to determine the tire wheel center position. The present invention takes the left front tire of the vehicle as an example of the tire to be tested, and before the test begins, the vehicle is in a ready state. The ready state means that the vehicle is fully equipped according to factory technical conditions, including on-board tools, spare tires, jacks, etc., and the fuel is not less than 90% of the tank capacity. Various oils and water meet the factory technical conditions and are fully equipped.

[0037] The tire has two circular surfaces. When the tire is equipped on a vehicle, when a person stands next to the tire, one circular surface of the tire facing the person is defined as the tire outer side surface 2, and the other circular surface is defined as the tire inner side surface 3; the distance between the tire outer side surface 2 and the tire inner side surface 3 is the tire width W, and the annular surface made of rubber between the tire outer side surface 2 and the tire inner side surface 3 is defined as the tire annular surface 4.

[0038] The outer side section of the tire is a plane tangent to the edge of the outer side surface 2 of the tire.

[0039] The tire inner side section is a plane tangent to the edge of the tire inner side 3 .

[0040] In the present invention, in Catia software, based on the point cloud of the vehicle tire, the rim outer section 6, the tire outer section 8 and the tire inner section 10 are fitted and generated, and based on the tire outer section 8 and the tire inner section 10, the tire center plane 11 is fitted and generated; at the same time, in Catia software, based on the rim outer section 6, the rim cross-sectional circle 13 is fitted and generated, and the center of the rim cross-sectional circle 13 is selected, and the center of the rim cross-sectional circle 13 is projected to the tire center plane 11. After projection, the center contour of the rim cross-sectional circle 13 is obtained on the tire center plane 11, and the point formed by the contour is the wheel center position of the vehicle tire.

[0041] A method for determining a wheel center position of a vehicle tire comprises the following steps:

[0042] Step 1: Inflate / deflate the vehicle tires to the standard tire pressure on the nameplate, place the vehicle on level ground, and load it to a ready state.

[0043] Step 2: Figure 1 and Figure 3 As shown, positioning marks 1 are pasted on the outer side surface 2 of the vehicle tire and the annular surface 4 of the tire except for the part touching the ground, and the positioning marks 1 are randomly distributed on the outer side surface 2 of the tire and the annular surface 4 of the tire.

[0044] Regarding the sticking of the positioning mark 1 on the tread just above the tire annular surface 4, due to the obstruction of the wheel cover above the tire, it is difficult to stick the positioning mark 1 on the part of the tread just above the tire annular surface 4 close to the inner side surface 3 of the tire. However, the tire is in a loaded state in a prepared state at this time. Therefore, at this time, as many positioning marks 1 as possible should be stuck on the part of the tread just above the tire annular surface 4 close to the inner side surface 3 of the tire, so as to facilitate the acquisition of the coordinate value of the positioning mark 1 on the tread just above the tire annular surface 4 when the tire is in a loaded state in a prepared state in step three.

[0045] Step 3: Establish the coordinate system of positioning point 1;

[0046] There are multiple positioning marks 1 on the outer surface of the tire, and the coordinate system of the positioning marks 1 includes the coordinate value of each positioning mark 1; the specific method is to open the VXScan module of the VXelements software on the computer, the computer is connected to a three-dimensional laser scanning device system, and the scanning positioning mark mode of the three-dimensional laser scanning device system is opened on the computer, starting from the positioning mark 1 at the center of the tire, and using a three-dimensional laser scanner to continuously scan the positioning marks 1 pasted on the tire. Through the positioning function of the three-dimensional laser scanning device system, the three-dimensional laser scanning device system identifies the coordinates of the positioning marks 1 pasted on the tire surface, and the VXelements software calculates and generates the spatial position of each positioning mark, thereby obtaining the coordinate system of the positioning marks 1 on the outer side surface 2 of the tire and the annular surface 4 of the tire. The coordinate system is a coordinate system established under the load state of the tire in a ready state.

[0047] Due to the obstruction of the wheel cover, some of the positioning marks 1 on the tread just above the annular surface 4 of the tire are difficult to identify. The lens of the three-dimensional laser scanning equipment system illuminates and identifies the positioning marks 1 on the tread just above the tire at as many angles as possible to obtain the coordinate values ​​of each positioning mark 1 on the tread just above the tire when the tire is in a ready state and under load.

[0048] Regarding the origin of the coordinate system of positioning point 1, the VXelements software automatically generates the origin of the coordinate system by selecting any point in the space.

[0049] Step 4: Remove the left front tire from the vehicle;

[0050] Since the tire is mounted on a vehicle, it is difficult to affix the positioning mark 1 to the inner side surface 3 of the tire and the portion just above the annular surface 4 of the tire close to the inner side surface 3 of the tire; Figure 2 As shown, after the tire is removed from the vehicle, positioning marks 1 are additionally pasted on the portion of the tread close to the inner side surface 3 of the tire just above the annular surface 4 of the tire and on the outer surface of the inner side surface 3 of the tire.

[0051] Step 5: Establish a coordinate system including the coordinate values ​​of the positioning mark 1 on the tire outer side 2, the tire inner side 3, and the tire annular surface 4;

[0052] Open the VXScan module of the VXelements software on the computer. The computer is connected to a 3D laser scanning device system. The scanning positioning and punctuation mode of the 3D laser scanning device system is opened on the computer.

[0053] like Figure 3 As shown, the three-dimensional laser scanning device system sequentially and continuously scans the positioning mark 1 on the outer side surface 2, the annular surface 4, and the inner side surface 3 of the tire; the positioning mark 1 on the outer side surface 2 and the annular surface 4 of the tire has been over-scanned in step three; the original positioning mark 1 on the outer side surface 2 and the annular surface 4 of the tire is scanned again in step five in order to obtain the basis of the coordinate system established in step three, so that the coordinate value of the positioning mark 1 supplemented and pasted in step five can be added to the coordinate system established in step three;

[0054] The VXelements software identifies the coordinate system established in step 3 according to the relative position of the original positioning mark 1 relative to the origin in step 2, locates the coordinate position of the additionally pasted positioning mark 1 through continuous scanning of the lens of the 3D laser scanning device system, and adds the coordinate value of the additionally pasted positioning mark 1 to the coordinate system established in step 3, and the coordinate system includes the coordinate values ​​of the positioning mark 1 on the outer side 2, the inner side 3, and the annular surface 4 of the tire;

[0055] The coordinate values ​​of the additionally pasted positioning mark 1 in step five are obtained by scanning when the tire is in an unloaded state, and the coordinate values ​​of some positioning mark 1 on the outer side surface 2 of the tire and the annular surface 4 of the tire in step three are obtained by scanning under a loaded state when the tire is in a ready state; the coordinate values ​​of the additionally pasted positioning mark 1 are added to the coordinate system established when the tire is in a loaded state in order to minimize the error in determining the tire wheel center position.

[0056] Step 6: Turn on the scanning surface mode and use the 3D laser scanning device system to obtain the 3D point cloud data of the left front tire of the vehicle;

[0057] Open the VXScan module of the VXelements software on the computer, import the coordinate system file in step 5 into the VXScan module, select the "Scan Surface" command in the VXScan module, and the 3D scanner included in the 3D laser scanning device system connected to the computer performs 3D point cloud scanning on the outer side 2 of the tire, the inner side 3 of the tire, and the annular surface 4 of the tire;

[0058] The purpose of establishing the coordinate system in step 3 and step 5 is to obtain the position of the positioning mark 1 pasted on the tire, so as to position the 3D scanner and determine the scanning position when the 3D scanner performs 3D point cloud data scanning. The 3D scanner only scans the surface of the object with the positioning mark 1 affixed; after selecting the "Scan Surface" command, the 3D scanner identifies the coordinate value of each positioning mark 1 in the coordinate system established in step 5, and irradiates the laser to the surface of the object where the positioning mark 1 is located, that is, the tire surface, to generate 3D point cloud data.

[0059] Step 7: Fit the rim tangent surface 6 of the tire. The rim tangent surface 6 is a plane tangent to the edge of the rim protrusion.

[0060] Open the Polyworks IMinspect module of the VXelements software, import the 3D point cloud data of the left front tire of the vehicle obtained in step 6 into the Polyworks IMinspect module, and use the command selection-brush, such as Figure 4 As shown, the point cloud of the protruding part 5 of the outer ring of the vehicle tire rim is selected, and the command Create Plane-Fit-Fit to Unit-Maximum is used. The VXelements software calculates and fits the plane generated according to the average position of the selected point cloud. The plane is the outer tangent surface 6 of the tire rim. Figure 4 The rim outer section 6 of the tire is represented by grid lines.

[0061] Step 8. Select the rim outer section 6, right-click the mouse, and select the "Output" command to save the plane features of the rim outer section 6 generated by fitting in step 8 as an igs format file.

[0062] Step 9. Open the CATIA software, click Start-DSE module of the CATIA software, and import the 3D point cloud data of the left front tire of the vehicle obtained in step 6 into the DSE module; open the plane feature igs format file of the rim circumferential surface 6 obtained in step 8, copy and paste the igs format file into the directory tree to which the 3D point cloud data of the left front tire belongs, and the 3D point cloud data of the left front tire and the plane feature igs file of the rim circumferential surface 6 are placed in the same file.

[0063] Step 10: Fit the outer section 8 of the tire based on CATIA software. Click Start-Shape-Generative Shape Design to enter the "Generative Shape Design" module. Click the command "Plane", the plane type "Offset Plane", the direction is Y direction, and select the rim outer section 6 generated by fitting. Figure 5As shown, the rim outer section 6 generated by fitting is dragged to the outside of the tire point cloud along the Y direction, and after being a certain distance away from the outer side of the tire point cloud, the outer plane 7 of the tire point cloud is obtained; regarding the said distance, the said distance value can be any value; use the command "Measure Distance", select the vehicle left front tire point cloud, and then select the outer plane 7 of the tire point cloud to obtain the distance between the tire point cloud and the outer plane 7 of the tire point cloud; use the command "Translate", select "Direction, Distance" in "Vector Definition", select the outer plane 7 of the tire point cloud as the element, select "zx plane" as the direction, input the distance value of the distance between the tire point cloud and the outer plane 7 of the tire point cloud, and fit to generate the outer section 8 of the tire.

[0064] Step 11: Based on CATIA software, fit the inner section of the tire 10, click the command "Plane", the plane type "Offset Plane", the direction is Y direction, and select the rim outer section 6 generated by fitting, such as Figure 6 As shown, the rim tangent surface 6 generated by fitting is dragged to the inside of the tire point cloud along the Y direction, and after being a certain distance away from the inner side of the tire point cloud, the inner plane 9 of the tire point cloud is obtained; regarding the said distance, the said distance value can be any value; use the command "Measure Distance", select the point cloud of the left front tire of the vehicle, and then select the inner plane 9 of the tire point cloud to obtain the distance between the tire point cloud and the inner plane 9 of the tire point cloud; use the command "Translate", select "Direction, Distance" in "Vector Definition", select the inner plane 9 of the tire point cloud as the element, select "zx plane" as the direction, input the distance value of the distance between the tire point cloud and the inner plane 9 of the tire point cloud, and fit to generate the inner section 10 of the tire.

[0065] The present invention is based on fitting the outer section 8 and the inner section 10 of the tire and finally determining the wheel center position of the tire. When the tire is installed on a vehicle, the ground contacting portion of the tire is defined as the bottommost surface of the tire. In the present invention, the point cloud data of the bottommost surface of the tire is not required, and the outer section 8 and the inner section 10 of the tire can also be generated by fitting through steps ten and eleven. Therefore, the present invention does not paste the positioning mark 1 on the bottommost surface of the tire.

[0066] Step 12: Based on CATIA software, fit the tire center plane 11, such as Figure 7 As shown, click the command "Measure Distance", select the outer section 8 and the inner section 10 of the tire, the Y distance between the outer section 8 and the inner section 10 of the tire is the tire width W, click the command "Plane", the plane type is "Offset Plane", the element selects the outer section 8 or the inner section 10, the direction is Y direction, the offset distance is W / 2, and the plane generated by fitting is the tire center plane 11.

[0067] Step 13: Fit the rim section circle 13 based on CATIA software. Click Start-Shape-DSE to enter the "DSE" module. Use the "Planar Section" tool of the "DSE" module. Select the rim point cloud in "Element" and select the rim tangent surface 6 in "Reference". Click and drag the rim tangent surface 6 in the Y direction to continuously and slightly adjust the position of the rim tangent surface 6. The slight adjustment refers to dragging the fitted rim tangent surface 6 a little bit with the mouse. Figure 8 As shown, until the mouse is dragged to adjust the rim external section 6 to cut out the rim edge circle 12, select the rim edge circle 12, click Apply, click OK, generate the cross-section line of the rim edge, click the "Circle" command, select "Three Points" as the circle type, select three points on the rim edge cross-section line, and generate a circle based on the three points. The circle generated by fitting is the rim cross-section circle 13, and the three points are on the circumference of the rim cross-section circle 13.

[0068] Step 14: Based on CATIA software, fit and generate the center of the rim cross-section circle. Specifically, click the command "Point", select the type "Circle / Sphere / Ellipse Center", select the rim cross-section circle 13, and the center point generated by fitting is the center of the rim cross-section circle 13.

[0069] Step 15. In the CATIA software, click the command "Project", select the center of the rim cross-section circle 13, select the tire center plane 11 as the support surface, and project the center of the rim cross-section circle 13 to the tire center plane 11. After projection, the center contour of the rim cross-section circle 13 is obtained on the tire center plane 11. The point formed by the contour is the wheel center position of the vehicle tire.

[0070] After determining the wheel center position of the vehicle tire, the vehicle parameters such as the static radius, wheelbase and track can be further determined in the CATIA software.

[0071] Finally, it should be noted that the contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field. The above description is only the preferred embodiment of the present invention and is not used to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions recorded in the aforementioned embodiments, or to replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0072] In the description of the present invention, it is necessary to understand that the terms "inside", "outside", "upper", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are 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 cannot be understood as a limitation on the present invention.

Claims

1. A method for determining the wheel center position of a vehicle tire, characterized in that: According to the point cloud of the vehicle tire, a rim outer section (6), a tire outer section (8) and a tire inner section (10) are fitted and generated, and according to the tire outer section (8) and the tire inner section (10), a tire center plane (11) is fitted and generated; according to the rim outer section (6), a rim cross-sectional circle (13) is fitted and generated, the center of the rim cross-sectional circle (13) is selected, and the center of the rim cross-sectional circle (13) is projected onto the tire center plane (11), and the center contour of the rim cross-sectional circle (13) is obtained on the tire center plane (11), and the point formed by the contour is the wheel center position of the vehicle tire; The method for obtaining the rim outer section (6) is to import the tire point cloud data into the IMinspect module of the VXelements software, select the point cloud of the protruding part (5) of the outer ring of the tire rim, use the command Create Plane-Fit-Fit to Unit-Maximum, calculate the fitting to generate a plane, and the plane is the tire rim outer section (6); The method for obtaining the tire outer section (8) is as follows: based on CATIA software, selecting the rim outer section (6) generated by fitting, dragging the rim outer section (6) generated by fitting to the outer side of the tire point cloud, and obtaining the tire point cloud outer plane (7); using the command "measure distance" to obtain the distance between the tire point cloud and the tire point cloud outer plane (7); using the command "translation", selecting "direction, distance" in "vector definition", selecting the tire point cloud outer plane (7) as the element, selecting "zx plane" as the direction, inputting the distance value as the distance between the tire point cloud and the tire point cloud outer plane 7, and generating the tire outer section (8); The method for obtaining the inner side section (10) of the tire is as follows: based on CATIA software, a rim outer section (6) generated by fitting is selected, and the rim outer section (6) generated by fitting is dragged to the inner side of the tire point cloud to obtain the inner side plane (9) of the tire point cloud; a "measure distance" command is used to obtain the distance between the tire point cloud and the inner side plane (9) of the tire point cloud; a "translation" command is used, "vector definition" is selected as "direction, distance", the element is selected as the inner side plane (9) of the tire point cloud, the direction is selected as "zx plane", and the distance value is input into the distance between the tire point cloud and the tire The distance between the inner plane (9) of the point cloud and the inner section (10) of the tire is generated; the method for obtaining the tire center plane (11) is to click the command "measure distance" based on CATIA software to obtain the distance W between the outer section (8) of the tire and the inner section (10) of the tire, wherein W is the tire width, click the command "plane", the plane type "offset plane", select the outer section (8) or the inner section (10) as the element, the direction is the Y direction, the offset distance is W / 2, and the generated plane is the tire center plane (11); The method for obtaining the rim cross-section circle (13) is as follows: based on CATIA software, a rim outer section (6) is selected, the position of the rim outer section (6) is adjusted until a rim edge circle (12) is formed, application and confirmation are clicked to generate a cross-section line of the rim edge, a "circle" command is clicked, and the type of circle is selected as "three points", and a circle is generated by fitting based on three points selected on the rim edge cross-section line, wherein the circle generated by fitting is the rim cross-section circle (13).

2. The method for determining the wheel center position of a vehicle tire according to claim 1, characterized in that: The vehicle tire point cloud acquisition comprises the following steps: ① Inflate / deflate the vehicle tire to the standard tire pressure indicated on the nameplate, place the vehicle on a level surface, load it to a ready state, and affix positioning marks (1) on the outer side surface (2) of the vehicle tire and the annular surface 4 of the tire except the part touching the ground; ② A three-dimensional laser scanning device system connected to a computer scans the outer side surface (2) of the vehicle tire and the positioning mark (1) on the annular surface of the tire to obtain the coordinate value of the positioning mark (1) and establish a coordinate system of the positioning mark (1); ③ Remove the tire from the vehicle, and paste additional positioning marks (1) on the portion of the tread just above the tire annular surface (4) and close to the tire inner side surface (3), and on the outer surface of the tire inner side surface (3), and sequentially scan the positioning marks (1) on the tire outer side surface (2), the tire annular surface (4), and the tire inner side surface (3) with a three-dimensional laser scanning device system, and add the coordinate values ​​of the additionally pasted positioning marks (1) to the coordinate system established in step ②, thereby obtaining a coordinate system including the coordinate values ​​of the positioning marks (1) on the tire outer side surface (2), the tire inner side surface (3), and the tire annular surface (4); ④ The three-dimensional laser scanning device system reads the coordinate values ​​of the positioning marks (1) on the tire, scans the outer surface of the tire with the positioning marks (1) attached, and obtains the tire point cloud.

3. The method for determining the wheel center position of a vehicle tire according to claim 2, characterized in that: The positioning marks (1) are arranged at intervals on the outer surface of the tire, and the distance between every two positioning marks (1) is 15-20 cm.

4. The method for determining the wheel center position of a vehicle tire according to claim 1, characterized in that: The plane features of the rim tangent surface (6) are stored in an igs format file, and the igs format file and tire point cloud data are both imported into CATIA software.

5. The method for determining the wheel center position of a vehicle tire according to claim 1, characterized in that: The center of the rim cross-section circle (13) is projected onto the tire center plane (11), and the center contour of the rim cross-section circle (13) is obtained on the tire center plane (11), and the point formed by the contour is the wheel center position of the vehicle tire.

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