Four-wheel positioning method and device based on multi-galvanometer line laser scanning
By using multi-mirror line laser scanning and binocular camera differential calculation, the problems of low accuracy, poor efficiency and safety hazards of existing four-wheel alignment methods have been solved, achieving efficient and accurate tire alignment and protection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-18
- Publication Date
- 2026-03-13
AI Technical Summary
Existing four-wheel alignment methods are complex to operate, have low accuracy and poor efficiency, and laser scanning is easily affected by ambient light and tire surface texture, resulting in incomplete measurement coverage and potential safety hazards.
Using multi-mirror laser scanning combined with a binocular camera, and through differential calculation and 3D reconstruction technology, 3D point cloud data of the tire surface is acquired, and positioning parameters are calculated.
It achieves efficient and accurate tire positioning, adapts to tires of different sizes, improves measurement accuracy and coverage, avoids tire scratches, and reduces the impact of environmental interference.
Smart Images
Figure CN121655428A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of four-wheel alignment technology, specifically a four-wheel alignment method based on multi-mirror line laser scanning. Background Technology
[0002] Four-wheel alignment is a crucial step in automotive repair and maintenance, directly impacting vehicle stability, handling performance, and tire lifespan. Traditional four-wheel alignment methods primarily rely on mechanical targets and manual measurements, which suffer from complexity, low accuracy, and inefficiency. With technological advancements, laser-based four-wheel alignment methods are gradually becoming the industry mainstream, but current technology still faces the following shortcomings: Existing four-wheel alignment methods are mainly divided into two categories: contact measurement and single-point laser measurement. Contact measurement requires mechanical clamps to hold the tire or rim, which is not only cumbersome to operate and has low detection efficiency, but also easily causes scratches on the tire surface. In addition, the measurement coverage is limited and it is difficult to fully reflect the true posture of the tire. Although single-point laser measurement achieves non-contact detection, it is limited by the characteristics of single-point scanning, and has problems such as low scanning efficiency and single laser stripe information. It is also easily affected by ambient light and reflection from the tire surface texture, resulting in large errors in the calculation of positioning parameters.
[0003] Meanwhile, existing laser scanning positioning technologies suffer from insufficient flexibility in adjusting the laser beam plane, making it difficult to adapt to tires of different sizes. This often results in incomplete scanning coverage, affecting the integrity of parameter calculations. Some technologies have not optimized the synchronization between laser scanning and image acquisition, leading to fragmented and blurred laser images, further reducing measurement accuracy. Furthermore, laser safety mechanisms are inadequate; the high energy characteristics of single-point lasers and continuous laser irradiation during abnormal galvanometer movement both pose potential safety hazards.
[0004] Therefore, there is an urgent need for a four-wheel alignment method that has high coverage, strong anti-interference ability, safety and reliability, and wide adaptability. Summary of the Invention
[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this application provides a four-wheel alignment method based on multi-mirror line laser scanning.
[0006] (II) Technical Solution To address the above problems, this application provides the following technical solution: A four-wheel alignment method based on multi-mirror line laser scanning includes: Multiple lasers were turned off to obtain a background image of the tire surface; Multiple lasers are activated to emit multiple line lasers onto the tire surface. Multiple dual-mirror assemblies control the deflection of the corresponding single line lasers. At the same time, a binocular camera exposes and captures the tire line laser image containing each deflection position. Perform a difference operation between the tire background image and the tire line laser image; Three-dimensional reconstruction is performed based on the difference operation results to obtain three-dimensional point cloud data of the tire surface; The tire positioning parameters are calculated based on 3D point cloud data.
[0007] Preferably, the step of turning off multiple lasers to acquire the tire background image on the tire surface specifically includes: By turning off multiple lasers and using a binocular camera to capture images of the tire surface, a background image of the tire is obtained.
[0008] Preferably, the dual-mirror assembly includes a first galvanometer and a second galvanometer; The first galvanometer is used to adjust the deflection angle, start or end position of the line laser plane in the vertical direction; The second galvanometer is used to adjust the starting position of the line laser plane in the horizontal direction to cover the edge of the tire.
[0009] Preferably, the speed of the first and second galvanometers is not less than N, and N is a positive number.
[0010] Preferably, the step of activating multiple lasers to emit multiple line lasers onto the tire surface, controlling the deflection of corresponding single line lasers through multiple dual-mirror assemblies, and simultaneously capturing tire line laser images including each deflection position using a binocular camera, specifically includes: Multiple lasers are activated to emit multiple lines of laser light onto the tire surface; Based on the width of the tire, the starting position of the corresponding single-line laser in the horizontal direction is adjusted by multiple second galvanometers so that multiple laser lines can cover the edge of the tire. After determining the horizontal direction of multiple laser lines, the starting position, multiple deflection positions and result positions of the corresponding single laser line in the vertical direction are adjusted and preset by multiple first galvanometers to obtain the deflection scanning path, and the deflection scanning path covers at least 80% of the effective area of the tire surface. Control multiple first galvanometers to deflect in steps or continuously according to a preset deflection scanning path; During multiple deflections of the first galvanometer, the binocular camera simultaneously performs a single exposure to acquire the tire line laser image.
[0011] Preferably, the step of performing a difference operation between the tire background image and the tire line laser image specifically includes: The initial difference image is obtained by performing pixel-level difference calculations between the tire laser image and the tire background image. The mathematical expression for the initial difference image is: (1) In formula (1), L represents the pixel coordinates, and L represents the grayscale value of the laser image pixel in the tire line. D represents the grayscale value of the background image pixels. Gray values of the difference image; Perform grayscale filtering on the initial difference image and set an adaptive grayscale threshold; when the grayscale value of a pixel in the initial difference image is greater than the adaptive grayscale threshold, the pixel is retained; when the grayscale value of a pixel in the initial difference image is less than or equal to the adaptive grayscale threshold, the pixel is discarded. The initial difference image after filtering is optimized by edge smoothing to obtain the difference image.
[0012] Preferably, the step of performing three-dimensional reconstruction based on the difference operation results to obtain three-dimensional point cloud data of the tire surface specifically includes: A sub-pixel precision extraction algorithm is used to extract the centerline pixel coordinates of each effective laser stripe from the differential image; Based on the parameters of the binocular camera system, stereo matching is performed on the matching center points of laser stripes belonging to the same line in the difference image; Based on the stereo matching results and the binocular camera system parameters, the coordinates of the three-dimensional spatial points corresponding to each pair of matching center points are calculated using the forward intersection method. All calculated coordinates of three-dimensional points are collected to form three-dimensional point cloud data representing the surface contour of the tire.
[0013] Preferably, the calculation of tire positioning parameters based on 3D point cloud data specifically includes: The three-dimensional point cloud data is preprocessed to remove noise points and outliers; The preprocessed 3D point cloud data is filtered to obtain an effective set of measurement points representing the spatial attitude of the tire. A tire surface model is established based on an effective set of measurement points, and the positioning parameters are calculated by combining the geometric relationship of the vehicle suspension system. The positioning parameters include at least the toe angle, camber angle, caster angle, and kingpin inclination angle.
[0014] A four-wheel alignment device based on multi-mirror line laser scanning, comprising: Multiple structural modules, each structural module including a dual-mirror assembly and a laser; the dual-mirror assembly includes a first galvanometer and a second galvanometer. A binocular camera is used to acquire line laser images and background images; A speed sensor is used to monitor the operating speed of the first and second galvanometers; An industrial control computer is used to receive data from the speed sensor and the binocular camera, perform image processing and analysis, and calculate the tire positioning parameters. The signal output terminals of the binocular camera and speed sensor are connected to the signal input terminals of the industrial control computer, and the signal output terminals of the industrial control computer are connected to the signal input terminals of the first galvanometer, the second galvanometer, and the laser.
[0015] (III) Beneficial Effects Compared with the prior art, this application provides a four-wheel positioning method based on multi-galvanometer line laser scanning, which has the following advantages: 1. This method, through the coordinated adjustment of the first and second galvanometers, can dynamically optimize the scanning path according to the tire width and diameter, ensuring that the laser scan covers no less than 80% of the effective area of the tire surface. Compared with traditional single-point laser scanning or contact measurement, it can capture the tire surface contour information more comprehensively. Combined with binocular vision 3D reconstruction technology, the 3D spatial coordinates of the laser stripes are accurately extracted from the differential image, providing a more complete and reliable data foundation for the calculation of positioning parameters, and significantly improving the calculation accuracy of core parameters such as toe angle and camber angle.
[0016] 2. This method employs a corresponding difference operation strategy for the background image and the line laser image. By separately differentiating the left and right camera images and using adaptive grayscale thresholding, it effectively eliminates interference factors such as ambient light and tire surface texture reflection, accurately preserving effective laser stripe information. Combined with edge smoothing optimization processing, it further improves the integrity and clarity of the laser stripes, enabling the method to work stably even in complex lighting environments such as workshop lighting fluctuations and external stray light incidence, reducing the impact of the environment on the measurement results.
[0017] 3. In this method, the second galvanometer can adaptively adjust the horizontal starting position of the laser according to the tire width, while the first galvanometer can flexibly preset the starting and ending positions and deflection paths in the vertical direction. This allows it to adapt to various tires, such as passenger car tires, of different widths and diameters without requiring hardware changes. Simultaneously, the stepping or continuous deflection of the first galvanometer is synchronized with the single exposure of the binocular camera, significantly shortening the scanning and acquisition time and resulting in a substantial improvement in efficiency compared to traditional contact measurement. 4. This method adopts a non-contact approach using line laser scanning and binocular vision acquisition throughout the process. It eliminates the need for mechanical clamps to directly contact the tire, fundamentally avoiding scratches and compression damage to the tire surface caused by traditional contact measurements. It is especially suitable for the inspection of high-end vehicles and new tires, balancing measurement accuracy with tire protection requirements.
[0018] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description
[0019] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the four-wheel alignment method based on multi-mirror line laser scanning according to this application; Figure 2 This is a schematic diagram showing the position of the center laser in the horizontal direction before and after adjustment in a four-wheel positioning method based on multi-mirror line laser scanning according to this application. Detailed Implementation
[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0021] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.
[0022] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.
[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0024] This application provides a novel technical solution: a four-wheel alignment method based on multi-galvanometer line laser scanning, comprising: Multiple lasers were turned off to obtain a background image of the tire surface; Multiple lasers are activated to emit multiple line lasers onto the tire surface. Multiple dual-mirror assemblies control the deflection of the corresponding single line lasers. At the same time, a binocular camera exposes and captures the tire line laser image containing each deflection position. Perform a difference operation between the tire background image and the tire line laser image; Three-dimensional reconstruction is performed based on the difference operation results to obtain three-dimensional point cloud data of the tire surface; The tire positioning parameters are calculated based on 3D point cloud data.
[0025] A four-wheel alignment device based on multi-mirror line laser scanning, comprising: Multiple structural modules, each structural module including a dual-mirror assembly and a laser; the dual-mirror assembly includes a first galvanometer and a second galvanometer. A binocular camera is used to capture tire line laser images and tire background images; A speed sensor is used to monitor the operating speed of the first and second galvanometers; An industrial control computer is used to receive data from the speed sensor and the binocular camera, perform image processing and analysis, and calculate the tire positioning parameters. The signal output terminals of the binocular camera and speed sensor are connected to the signal input terminals of the industrial control computer, and the signal output terminals of the industrial control computer are connected to the signal input terminals of the first galvanometer, the second galvanometer, and the laser.
[0026] In a specific embodiment, one positioning device positions one tire, and four positioning devices position four tires.
[0027] The industrial computer is configured to perform the following operations: The laser is controlled to plan a scanning path according to the tire size, and the first and second galvanometers are driven to deflect in coordination. The binocular camera is controlled to acquire a tire background image when the laser is off, and to acquire a tire line laser image by single exposure when the laser is on and the galvanometer is deflected. The tire background image and the tire line laser image are subjected to a difference operation, and a three-dimensional point cloud of the tire surface is obtained by three-dimensional reconstruction based on the difference result. Calculate wheel positioning parameters based on the three-dimensional point cloud data; The movement speed of the first and second galvanometers is monitored in real time, and the line laser is turned off when the detected speed is lower than a safety threshold.
[0028] In this invention, the step of shutting down multiple lasers to obtain a tire background image of the tire surface specifically includes: By turning off multiple lasers and using a binocular camera to capture images of the tire surface, a background image of the tire is obtained.
[0029] In this invention, the dual-mirror assembly includes a first galvanometer and a second galvanometer; The first galvanometer is used to adjust the deflection angle, start or end position of the line laser plane in the vertical direction; The second galvanometer is used to adjust the starting position of the line laser plane in the horizontal direction to cover the edge of the tire.
[0030] In a specific embodiment, such as Figure 2 This is a schematic diagram showing the position of the line laser in the horizontal direction before and after the second galvanometer is adjusted. The blue line is the default starting position of the line laser in the horizontal direction, and the orange line is the adjusted starting position of the line laser in the horizontal direction.
[0031] In this invention, the movement speed of the first galvanometer and the second galvanometer is not less than the safety threshold N, and the safety threshold N is a positive number.
[0032] In a specific embodiment, the safety threshold N can be customized. When the movement speed of the first and second galvanometers is less than the safety threshold N, the laser is automatically shut off. Compared to point lasers, line lasers have a more dispersed energy distribution and a wider illumination range, significantly reducing the potential hazards to operators and equipment under any detection conditions.
[0033] In this invention, multiple lasers are activated to emit multiple line lasers onto the tire surface. Multiple dual-mirror assemblies control the deflection of corresponding single line lasers. Simultaneously, a binocular camera captures and exposes a tire line laser image including each deflection position. Specifically, this includes: Multiple lasers are activated to emit multiple lines of laser light onto the tire surface; Based on the width of the tire, the starting position of the corresponding single-line laser in the horizontal direction is adjusted by multiple second galvanometers so that multiple laser lines can cover the edge of the tire. After determining the horizontal direction of multiple laser lines, the starting position, multiple deflection positions and result positions of the corresponding single laser line in the vertical direction are adjusted and preset by multiple first galvanometers to obtain the deflection scanning path, and the deflection scanning path covers at least 80% of the effective area of the tire surface. Control multiple first galvanometers to deflect in steps or continuously according to a preset deflection scanning path; During multiple deflections of the first galvanometer, the binocular camera simultaneously performs a single exposure to acquire the tire line laser image.
[0034] In this invention, the step of performing a difference operation between the tire background image and the tire line laser image specifically includes: The initial difference image is obtained by performing pixel-level difference calculations between the tire laser image and the tire background image. The mathematical expression for the initial difference image is: (1) In formula (1), L represents the pixel coordinates, and L represents the grayscale value of the laser image pixel in the tire line. D represents the grayscale value of the background image pixels. Gray values of the difference image; Perform grayscale filtering on the initial difference image and set an adaptive grayscale threshold; when the grayscale value of a pixel in the initial difference image is greater than the adaptive grayscale threshold, the pixel is retained; when the grayscale value of a pixel in the initial difference image is less than or equal to the adaptive grayscale threshold, the pixel is discarded. The initial difference image after filtering is optimized by edge smoothing to obtain the difference image.
[0035] In this invention, the step of performing three-dimensional reconstruction based on the difference operation results to obtain three-dimensional point cloud data of the tire surface specifically includes: A sub-pixel precision extraction algorithm is used to extract the centerline pixel coordinates of each effective laser stripe from the differential image; Based on the parameters of the binocular camera system, stereo matching is performed on the matching center points of laser stripes belonging to the same line in the difference image; Based on the stereo matching results and the binocular camera system parameters, the coordinates of the three-dimensional spatial points corresponding to each pair of matching center points are calculated using the forward intersection method. All calculated coordinates of three-dimensional points are collected to form three-dimensional point cloud data representing the surface contour of the tire.
[0036] In this invention, the calculation of tire positioning parameters based on three-dimensional point cloud data specifically includes: The three-dimensional point cloud data is preprocessed to remove noise points and outliers; The preprocessed 3D point cloud data is filtered to obtain an effective set of measurement points representing the spatial attitude of the tire. A tire surface model is established based on an effective set of measurement points, and the positioning parameters are calculated by combining the geometric relationship of the vehicle suspension system. The positioning parameters include at least the toe angle, camber angle, caster angle, and kingpin inclination angle.
[0037] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0038] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A four-wheel positioning method based on multi-mirror line laser scanning, characterized in that, include: Multiple lasers were turned off to obtain a background image of the tire surface; Multiple lasers are activated to emit multiple line lasers onto the tire surface. Multiple dual-mirror assemblies control the deflection of the corresponding single line lasers. At the same time, a binocular camera exposes and captures the tire line laser image containing each deflection position. Perform a difference operation between the tire background image and the tire line laser image; Three-dimensional reconstruction is performed based on the difference operation results to obtain three-dimensional point cloud data of the tire surface; The tire positioning parameters are calculated based on 3D point cloud data.
2. The four-wheel positioning method based on multi-mirror line laser scanning according to claim 1, characterized in that, The process of shutting down multiple lasers to obtain a tire background image of the tire surface specifically includes: By turning off multiple lasers and using a binocular camera to capture images of the tire surface, a background image of the tire is obtained.
3. The four-wheel positioning method based on multi-galvanometer line laser scanning according to claim 1, characterized in that, The dual-mirror assembly includes a first mirror and a second mirror; The first galvanometer is used to adjust the deflection angle, start or end position of the line laser plane in the vertical direction; The second galvanometer is used to adjust the starting position of the line laser plane in the horizontal direction to cover the edge of the tire.
4. The four-wheel positioning method based on multi-mirror line laser scanning according to claim 3, characterized in that, The speed of the first and second galvanometers is not less than the safety threshold N, and the safety threshold N is a positive number.
5. A four-wheel positioning method based on multi-mirror line laser scanning according to claim 3, characterized in that, The process involves activating multiple lasers to emit multiple line laser beams onto the tire surface, controlling the deflection of corresponding single line laser beams through multiple dual-mirror assemblies, and simultaneously capturing tire line laser images at each deflection position using a binocular camera. Specifically, this includes: Multiple lasers are activated to emit multiple lines of laser light onto the tire surface; Based on the width of the tire, the starting position of the corresponding single-line laser in the horizontal direction is adjusted by multiple second galvanometers so that multiple laser lines can cover the edge of the tire. After determining the horizontal direction of multiple laser lines, the starting position, multiple deflection positions and result positions of the corresponding single laser line in the vertical direction are adjusted and preset by multiple first galvanometers to obtain the deflection scanning path, and the deflection scanning path covers at least 80% of the effective area of the tire surface. Control multiple first galvanometers to deflect in steps or continuously according to a preset deflection scanning path; During multiple deflections of the first galvanometer, the binocular camera simultaneously performs a single exposure to acquire the tire line laser image.
6. The four-wheel positioning method based on multi-mirror line laser scanning according to claim 1, characterized in that, The step of performing a difference operation between the tire background image and the tire line laser image specifically includes: The initial difference image is obtained by performing pixel-level difference calculations between the tire laser image and the tire background image. The mathematical expression for the initial difference image is: （1） In formula (1), L represents the pixel coordinates, and L represents the grayscale value of the laser image pixel in the tire line. The grayscale values of the background image pixels are represented by D, and the grayscale values of the initial difference image are represented by D. Perform grayscale filtering on the initial difference image and set an adaptive grayscale threshold; when the grayscale value of a pixel in the initial difference image is greater than the adaptive grayscale threshold, the pixel is retained; when the grayscale value of a pixel in the initial difference image is less than or equal to the adaptive grayscale threshold, the pixel is discarded. The initial difference image after filtering is optimized by edge smoothing to obtain the difference image.
7. A four-wheel positioning method based on multi-mirror line laser scanning according to claim 6, characterized in that, The step of performing three-dimensional reconstruction based on the difference operation results to obtain three-dimensional point cloud data of the tire surface specifically includes: A sub-pixel precision extraction algorithm is used to extract the centerline pixel coordinates of each effective laser stripe from the differential image; Based on the parameters of the binocular camera system, stereo matching is performed on the matching center points of laser stripes belonging to the same line in the difference image; Based on the stereo matching results and the binocular camera system parameters, the coordinates of the three-dimensional spatial points corresponding to each pair of matching center points are calculated using the forward intersection method. All calculated coordinates of three-dimensional points are collected to form three-dimensional point cloud data representing the surface contour of the tire.
8. A four-wheel positioning method based on multi-mirror line laser scanning according to claim 1, characterized in that, The calculation of tire positioning parameters based on 3D point cloud data specifically includes: The three-dimensional point cloud data is preprocessed to remove noise points and outliers; The preprocessed 3D point cloud data is filtered to obtain an effective set of measurement points representing the spatial attitude of the tire. A tire surface model is established based on an effective set of measurement points, and the positioning parameters are calculated by combining the geometric relationship of the vehicle suspension system. The positioning parameters include at least the toe angle, camber angle, caster angle, and kingpin inclination angle.
9. A four-wheel alignment device based on multi-galvanometer line laser scanning, comprising: Multiple structural modules, each structural module including a dual-mirror assembly and a laser; the dual-mirror assembly includes a first galvanometer and a second galvanometer. A binocular camera is used to capture tire line laser images and tire background images; A speed sensor is used to monitor the operating speed of the first and second galvanometers; An industrial control computer is used to receive data from the speed sensor and the binocular camera, perform image processing and analysis, and calculate the tire positioning parameters. The signal output terminals of the binocular camera and speed sensor are connected to the signal input terminals of the industrial control computer, and the signal output terminals of the industrial control computer are connected to the signal input terminals of the first galvanometer, the second galvanometer, and the laser.