Pavement anti-skid performance evaluation method and evaluation device based on envelope characteristics

Abstract

The present invention belongs to the technical field of pavement anti-skid performance testing, and relates to a pavement anti-skid performance evaluation method and evaluation device based on envelope features. The method comprises the following steps: 1) capturing a surface contour image of a test piece as a blank background image; 2) capturing an image of the motion trajectory of a sliding member on the test piece; 3) sequentially processing the blank background image to obtain a surface texture profile curve of the test piece; 4) performing subtraction of the motion trajectory image with the blank background image, and processing the image to obtain a trajectory envelope curve of the sliding member's motion; 5) calculating the arithmetic mean of the trajectory envelope curve and the arithmetic mean of the surface texture profile curve, and evaluating the anti-skid performance based on the height difference Δh between the two arithmetic mean values. The evaluation method of the present invention has good correlation, high processing efficiency, and accurate evaluation, thereby more effectively ensuring driving safety.

Description

Technical Field

[0001] The present invention belongs to the technical field of road surface anti-skid performance detection, and relates to a road surface anti-skid performance evaluation method and evaluation device based on envelope characteristics. Background Art

[0002] Pavement skid resistance is closely linked to vehicle safety, and insufficient pavement skid resistance is a significant contributing factor to frequent traffic accidents. Generally speaking, pavement skid resistance is closely related to its macro- and micro-texture. At high speeds and wet surfaces, the pavement's macrostructure plays a dominant role in skid resistance, while at low speeds, the pavement's microstructure plays a dominant role. Therefore, pavement texture depth, as a key indicator of pavement texture, is widely used in evaluating pavement skid resistance. However, existing evaluation metrics only measure different pavement texture characteristics. Friction, however, is the complex contact characteristics between tire rubber and the road surface under varying conditions. It is a comprehensive characterization dependent on pavement material, dimensional parameters, texture characteristics, load, pressure information, operating mode, and environmental factors. Furthermore, the specific quantitative relationship between pavement texture range and friction contribution remains unclear. Traditional testing methods that use simple pavement texture characteristic metrics to describe tire-road friction behavior suffer from significant human interference, low test efficiency, and a poor correlation between skid resistance evaluation metrics and pavement skid resistance, resulting in poor evaluation accuracy. Summary of the Invention

[0003] In response to the technical problems of low testing efficiency and poor accuracy in the existing technology, the present invention provides a road anti-skid performance evaluation method and evaluation device based on envelope characteristics, which have good correlation, high processing efficiency and accurate evaluation, thereby more effectively ensuring driving safety.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for evaluating the anti-skid performance of a pavement based on envelope characteristics comprises the following steps:

[0006] 1) Collect the surface profile image of the test piece as a blank background image;

[0007] 2) collecting the motion trajectory image of the sliding part on the test piece;

[0008] 3) The blank background image is subjected to grayscale processing, filtering and denoising, and binarization processing in sequence to obtain a black and white binary background image, and the surface texture contour edge pixel information of the test piece is extracted from the black and white binary background image to obtain the surface texture contour curve of the test piece;

[0009] 4) Subtracting the motion trajectory image obtained in step 2) from the blank background image in step 1), retaining the state information of the test piece, and obtaining a difference image; performing grayscale processing, noise reduction, and threshold segmentation on the difference image to obtain multiple motion images of the slider on the test piece; extracting the lowest point information of the slider from each motion image; performing trajectory fitting on the lowest point information of the slider during each motion process; and taking the fitting curve as the trajectory envelope curve of the slider on the test piece;

[0010] 5) Calculate the arithmetic mean of the trajectory envelope curve in step 4) and the arithmetic mean of the surface texture profile curve in step 3), and define the height difference between the two arithmetic means as the anti-slip performance index Δh of the test piece. The anti-slip performance between the sliding part and the test piece is evaluated by the size of Δh.

[0011] The steps 3), 4) and 5) are all completed by MATLAB.

[0012] Furthermore, the sliding member in step 2) is a rubber slider or a tire; and the test piece in step 1) is a road surface or a friction test piece.

[0013] Furthermore, in step 5), the smaller the Δh value is, the better the anti-slip performance of the test piece is; conversely, the larger the Δh value is, the worse the anti-slip performance of the test piece is.

[0014] An evaluation device for implementing the above-mentioned method for evaluating the anti-skid performance of a pavement based on envelope features comprises a base plate, a friction test piece, a rubber slider, a high-speed camera, a fixing fixture, and a pendulum instrument; the fixing fixture is placed on the base plate, the friction test piece is placed on the fixing fixture, the pendulum instrument is placed above the fixing fixture and connected to the base plate, the rubber slider is placed on the pendulum instrument and slides on the friction test piece; the high-speed camera is connected to the base plate and is located in front of the pendulum instrument.

[0015] Furthermore, the evaluation device includes a fill light placed on the bottom plate; the fill light is located between the high-speed camera and the pendulum instrument.

[0016] Furthermore, the evaluation device also includes a lifting mechanism connected to the base plate; the lifting mechanism includes a lifting platform and a lifting knob; the lifting platform is connected to the base plate through the lifting knob, and the lifting platform moves up and down along the vertical direction of the base plate; the high-speed phase is placed on the lifting platform.

[0017] Furthermore, the evaluation device also includes a computer connected to the high-speed camera.

[0018] Furthermore, the evaluation device also includes a pad arranged on the bottom plate; a leveling knob is provided on the pad, and the leveling knob is connected to the pendulum instrument.

[0019] An evaluation device for implementing the above-mentioned method for evaluating the anti-skid performance of a road surface based on envelope characteristics comprises a high-speed camera, a fill light, a tire, a road surface, and a lateral force test vehicle; the lateral force test vehicle is placed on the road surface, and the high-speed camera, fill light, and tire are all placed on the lateral force test vehicle, with the high-speed camera and fill light facing the hub surface of the tire.

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

[0021] 1. The new evaluation index proposed in this invention reflects the change in contact area under different conditions by characterizing the approach and separation process of two contact surfaces (i.e., the road surface and the tire surface). It has a good correlation with the friction performance of the road surface and can more accurately characterize the anti-skid performance of the tire rubber and the road surface.

[0022] 2. Compared with the traditional anti-skid performance testing method based on road surface texture, the evaluation method provided by the present invention takes into account the influence of external factors such as contact surface characteristics, load, temperature and humidity on anti-skid performance. The test method characterizes the variable characteristics of tire-road contact under different conditions.

[0023] 3. The present invention uses a high-speed camera to capture moving images of the road surface and tire rolling, extracts image texture information and then processes it, obtains the road surface texture contour curve and the envelope curve during tire sliding, and realizes anti-skid performance evaluation and prediction. It has the characteristics of simple operation, high processing efficiency, and accurate evaluation, thereby more effectively ensuring driving safety.

[0024] 4. The present invention uses two different testing devices to evaluate the anti-skid performance of the road surface. It is flexible and simple to use, has a simple operation process, reduces the influence of human factors, has low testing costs and high testing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the base plate provided by the present invention;

[0026] Figure 2 Schematic diagram of the anti-skid performance evaluation device of the present invention;

[0027] Figure 3 is a flow chart of the anti-skid performance evaluation method provided by the present invention;

[0028] Figure 4 This is an interface diagram of the image acquisition system of the present invention;

[0029] Figure 5 It is based on the MATLAB image processing steps diagram;

[0030] Figure 6 The background image, left and right positioning images, and sliding process image collected in Example 1 of the present invention;

[0031] Figure 7This is the image output result diagram of Example 1 of the present invention;

[0032] Figure 8 This is a diagram of an image acquisition method according to embodiment 2 of the present invention;

[0033] in:

[0034] 1—Base plate; 2—Fixed fixture; 3—Spacer; 4—Pendulum tester; 5—Friction test piece; 6—Fill light; 7—Fixed screw; 8—High-speed camera; 9—Lifting platform; 10—Lifting knob; 11—Leveling knob; 12—Rubber slider; 13—Computer; 14—Road surface; 15—Tire. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0036] Most studies have shown that the contact area between the tire and the road is closely related to the road's anti-skid performance. The larger the contact area, the better the anti-skid performance. The change in tire-road contact area under different conditions actually refers to the approach and separation process of the two contact surfaces (i.e., the road surface and the tire surface).

[0037] Simply put, the road surface can be characterized by a texture profile curve, while the tire surface can be characterized by an envelope curve during rolling. Because the comprehensive characterization of the contact characteristics of the two contact surfaces varies with the contact surface, load, operating mode, and environmental factors, the contact characteristic index between the tire envelope curve and the road texture curve can achieve a variable representation of the road surface's anti-skid performance. This is more accurate and scientific than existing evaluation methods and indicators. Therefore, a device and method for evaluating road surface anti-skid performance based on tire envelope characteristics have been proposed.

[0038] The evaluation method of the present invention characterizes the anti-skid performance of the road surface based on the relative relationship between the tire envelope curve and the road surface texture contour curve. That is, by collecting images of the tire moving on the road surface, eliminating the influence of noise texture and other apparent features, extracting road surface texture information and tire envelope feature information from them, and establishing a correlation model between image texture parameters and road surface anti-skid indicators, the anti-skid performance evaluation and prediction based on the tire envelope characteristics can be realized.

[0039] The anti-skid performance test method provided by the present invention can be used to evaluate the anti-skid performance of a rubber slider and a test piece based on a pendulum instrument, and can also be used to evaluate the anti-skid performance of an outdoor regular cross-section road surface based on a lateral force friction coefficient test vehicle. In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0040] Example 1

[0041] The present invention provides an embodiment of a road surface anti-skid performance evaluation device based on tire envelope characteristics.

[0042] See also Figure 1 and Figure 2 The present invention also provides a road anti-skid performance evaluation device based on tire envelope characteristics, including a base plate 1, a friction test piece 5, a high-speed camera 8, a fixed fixture 2 and a pendulum instrument 4; the fixed fixture 2 is placed on the base plate 1, the friction test piece 5 is placed on the fixed fixture 2, the pendulum instrument 4 is placed above the fixed fixture 2 and connected to the base plate 1, and the pendulum instrument 4 is connected to the friction test piece 5; the high-speed camera 8 is connected to the base plate 1 and is located in front of the pendulum instrument 4.

[0043] The evaluation device includes a fill light 6 placed on the bottom plate 1 ; the fill light 6 is located between the high-speed camera 8 and the pendulum instrument 4 .

[0044] The evaluation device also includes a lifting mechanism connected to the base plate 1; the lifting mechanism includes a lifting platform 9 and a lifting knob 10; the lifting platform 9 is connected to the base plate 1 through the lifting knob 10, and the lifting platform 9 moves up and down vertically along the base plate 1; the high-speed camera 8 is placed on the lifting platform 9.

[0045] The evaluation device also includes a computer 13 connected to the high-speed camera 8. The computer 13 is portable and is used to set the image acquisition mode and parameters, store the acquired images, and process the images. MATLAB software is installed on the computer 13, and image processing is all completed using MATLAB.

[0046] The evaluation device also includes pads 3 mounted on the base plate 1; these pads are equipped with leveling knobs 11, which are connected to the pendulum instrument 4. During implementation, three pads 3 are provided, located on the left, right, and rear sides of the pendulum instrument 4. The pendulum instrument 4 is connected to the leveling knobs 11, and the horizontal position of the pendulum instrument 4 is adjusted using these leveling knobs. The friction specimen 5 is placed on the fixture 2 and secured with a fixing screw 7. The pendulum of the pendulum instrument 4 is equipped with a rubber slider 12, which rubs against the friction specimen 5 as the pendulum swings.

[0047] The pendulum instrument 4 used in this embodiment simulates the friction behavior between the tire and the road surface on a real road during the friction process of the friction test piece 5. The surface of the friction test piece 5 can first be replaced by a 3D printed test piece with different texture depths and texture shapes instead of the real road surface. The friction test piece 5 is the road surface, and the rubber slider 12 is the tire; it is used to establish a correlation model between the anti-skid evaluation index and the anti-skid performance of the road surface.

[0048] See also Figure 3 The pavement anti-skid performance evaluation method based on envelope characteristics provided in this embodiment specifically includes the following steps.

[0049] S1: Assembly and debugging of high-speed camera acquisition equipment

[0050] The main equipment includes: a base plate 1, a high-speed camera 8, a pendulum tester 4, supplemental lights 6, and a computer 13. The base plate 1 is used to fix the relative positions of the friction specimen 5 and the pendulum tester 4. The high-speed camera 8 is an industrial camera, the pendulum tester 4 is a BM-III pendulum friction coefficient tester, and the supplemental lights 6 are two rectangular LED light sources with adjustable brightness.

[0051] See also Figure 2 The assembly process of the image acquisition equipment is as follows: place the pendulum instrument 4 and the test piece (friction test piece 5) at the calibration positions on the base plate 1 respectively, rotate the fixing screw 7 to lock the friction test piece 5, at this time, the pendulum of the pendulum instrument 4 can just fall into the middle position of the friction test piece 5, then use the leveling knob 11 to level, zero, and calibrate the sliding length (126mm) of the pendulum instrument 4, then fix the high-speed camera 8 on the lifting platform 9, adjust the lifting knob 10 so that the distance from the plane of the lifting platform 9 to the plane of the base plate 1 is 65mm, at this time the height from the center of the high-speed camera 8 to the bottom surface is 80mm, and at the same time adjust the distance from the front end of the high-speed camera 8 to the outer edge of the friction test piece 5 to 185mm, place the fill light 6 between the high-speed camera 8 and the friction test piece 5, and finally connect the high-speed camera 8 to the computer 13.

[0052] During implementation, in order to improve image quality and reduce image noise, the equipment area outside the friction test piece 5 was wrapped with light-absorbing cloth, and the black rubber slider 12 (sliding part) on the pendulum instrument 4 was marked with high-gloss paint.

[0053] S2: Image acquisition system parameter settings

[0054] Image acquisition software interface Figure 4 The image acquisition software is used to realize the soft trigger mode acquisition of the rubber slider 12 tracks, including the image storage parameter setting and the camera parameter setting. Figure 4 Set the acquisition parameters as shown in the figure.

[0055] The steps for setting image storage parameters are as follows: adjust the camera acquisition mode to soft trigger mode, set the trigger frame rate to 500, trigger 500 times per second, last for 1 second, save 300 images per trigger, set the save address and image format, and select automatic save mode.

[0056] The camera parameter settings are as follows: First, set the image resolution to 1280*1024. Next, configure the camera exposure control, selecting manual exposure control, setting the analog gain to 6x, and the exposure time to 0.5s. Once these settings are complete, adjust the aperture and focus using the two knobs on the front of the camera until the image is clear. This allows you to begin capturing images of the rubber slider's trajectory.

[0057] S3: High-speed camera image acquisition

[0058] Before collecting the sliding trajectory of the rubber slider 12 on the friction test piece 5, a blank background image and a left and right positioning image of the pendulum of the pendulum instrument 4 should be collected first. The specific collection steps are as follows:

[0059] (1) Keep the pendulum in the horizontal release position, with the pointer close to the pendulum, and then soft trigger once to save a blank background image;

[0060] (2) Lower the pendulum until the edge of the rubber slider 12 just touches the friction test piece 5, align with one end of the 126mm ruler, soft trigger once, save a right-side positioning diagram, then lift the lifting handle by hand to lift the slider upward. At the same time, the edge of the rubber slider 12 touches the friction test piece 5 again, align with one end of the 126mm ruler, soft trigger once, save a left-side positioning diagram;

[0061] (3) When the friction specimen 5 is dry (if it is wet, sprinkle water on the specimen evenly), place the pendulum in the horizontal release position, press the pendulum release switch and click the soft trigger at the same time, so that the pendulum slides over the friction specimen 5, and the pointer can indicate the friction coefficient value of the friction specimen 5; when the pendulum swings back, catch the pendulum rod with your left hand, lift the lifting handle with your right hand to raise the rubber slider 12, move the pendulum to the right and press the switch to make the pendulum length ring enter the release switch, and move the pendulum needle close to the needle plate.

[0062] Repeat the above steps five times (if the surface is wet, sprinkle water each time) and record the value each time. The difference between the five values ​​should not exceed three units (i.e. one and a half divisions on the dial). If the difference is greater than three units, investigate the cause and repeat the above steps again until the specified requirements are met.

[0063] S4: Image processing workflow based on MATLAB

[0064] In order to obtain the sliding envelope curve of the rubber slider 12 on the friction specimen 5 and the surface profile curve of the specimen, the blank background image, left and right positioning images, and images during the sliding process collected by S3 are used. Figure 5 Identify the steps shown.

[0065] (1) Read in a blank background image, convert the collected blank background image from an RGB image into a grayscale image through grayscale processing, use a filtering method to remove image noise, select a suitable threshold, convert the image into a black and white binary image, and finally extract the edge information of the surface texture contour of the friction specimen 5 to obtain the surface texture contour curve of the friction specimen 5; Figure 6 shown.

[0066] When processing these images, they were first converted to grayscale. Filtering and denoising were performed using the existing median filter method, effectively removing salt-and-pepper noise from the grayscale images. Since each set of collected images may differ, the threshold conversion value was adjusted based on the actual conditions of each image, taking into account factors such as light intensity, to ensure clear texture edges in the thresholded image. The threshold value was adjusted between 150 and 200.

[0067] (2) Read the left and right positioning maps and the images during the sliding process, and subtract these images from the blank background image in turn to retain the slider state information and remove other parts of the image that affect the recognition result to obtain the difference image. The difference image is converted into a grayscale image, and image noise reduction and threshold segmentation are performed to obtain the corresponding black and white binary image. The processed left and right positioning maps and the sliding process images are shown in Figure 2. Figure 6 The processing method is the same as step (1).

[0068] The lowest contact point information between the rubber slider 12 and the surface of the friction specimen 5 is then extracted from each image, and the positions of the left and right positioning points of the rubber slider 12 are recorded. At the same time, trajectory fitting is performed on the characteristic points (lowest point information) of the sliding process, and the fitting curve within the range of the left and right positioning lines is taken as the trajectory envelope curve of the rubber slider 12 sliding on the friction specimen 5.

[0069] (3) Combining the surface texture profile curve obtained in step (1) and the trajectory envelope curve of the rubber slider 12 sliding on the friction test piece 5 obtained in step (2), the final image processing result to be output is as follows: Figure 7 shown.

[0070] In this embodiment, the surface texture contour curve is a rectangle, triangle, circle or other texture shapes of different heights. The trajectory envelope curve is related to the coordinates of each point in the collected image. The trajectory envelope curve is obtained using the cubic spline curve interpolation function of MATLAB.

[0071] (4) The height difference between the arithmetic mean of the trajectory envelope curve and the arithmetic mean of the surface texture profile curve is calculated as Δh. The size of Δh reflects the change in the contact area between the slider and the specimen surface under different conditions to characterize the anti-slip performance.

[0072] Table 1 below compares the results of the evaluation method of the present invention and the traditional evaluation method for 3D printed friction test pieces with rectangular surface textures, a texture height of 2 mm, and texture spacings of 2 mm to 12 mm.

[0073] Among them, the traditional method is to evaluate the anti-skid performance of the road surface by measuring the friction coefficient using a construction depth and a pendulum tribometer.

[0074] Table 1 Comparison of test results of friction specimen and rubber slider

[0075]

[0076] As shown in Table 1, the traditional evaluation method using structural depth to evaluate the anti-skid performance of a pavement fails to reflect the impact of external environmental load conditions such as water on the anti-skid performance. Although the friction coefficient and the evaluation index Δh proposed in this invention can well reflect the changes in the anti-skid performance of the friction test piece under different environments, the friction coefficient is only a simple mechanical result value and cannot reflect the dynamic contact process between the sliding part and the test piece, thus making it impossible to deeply explore the source and temporal and spatial evolution of friction behavior.

[0077] In addition, it can be seen from Table 1 that, using the evaluation method of the present invention, when the texture spacing of the friction specimen continues to increase, the contact area between the rubber slider and the friction specimen gradually decreases, and the anti-slip performance decreases accordingly; the anti-slip performance of the friction specimen under dry conditions is better than that under wet conditions.

[0078] Since the size of Δh is related to the contact area between the sliding part and the test piece, the smaller the Δh value, the larger the contact area between the tire and the road surface, and the better the anti-skid performance. Conversely, the larger the Δh value, the smaller the contact area between the sliding part and the test piece, and the worse the anti-skid performance.

[0079] Example 2

[0080] In this embodiment, a high-speed camera 8 is installed on the bottom of the lateral force friction coefficient test vehicle to capture the motion image of the tire on a regularly textured road surface, obtain the tire envelope curve and the road surface texture curve, and calculate the height difference Δh between the arithmetic mean of the tire envelope curve and the arithmetic mean of the road surface texture contour curve to evaluate the anti-skid performance of the tire and the road surface.

[0081] The collection method provided in this embodiment is as follows Figure 8The lateral force friction coefficient test vehicle is a lateral force test vehicle. A high-speed camera 8 and a fill light 6 are mounted on the bottom of the lateral force test vehicle to capture images of a tire 15 moving on a regular cross-sectional road surface 14. The tire 15 is then placed on a test wheel of the lateral force test vehicle.

[0082] The method for testing the anti-skid performance of a vehicle based on the lateral force friction coefficient provided in this embodiment specifically includes the following steps:

[0083] (1) Install and secure the high-speed camera 8 and fill light 6 at the bottom of the crossbar of the lateral force test vehicle, ensuring that the high-speed camera 8 and fill light 6 are installed at the same angle, facing the side of the tire 15, i.e., the hub surface, to capture the motion image of the tire 15 on the road surface 14. The high-speed camera 8 is electrically connected to the computer 13. The frame rate of the high-speed camera 8 is selected according to the test rate of the lateral force test vehicle.

[0084] (2) Start the image acquisition software and perform image storage and camera parameter settings in sequence.

[0085] The steps for setting up image storage are as follows: adjust the camera acquisition mode to soft trigger mode, set the number of images saved per single trigger to 300, save the address and image format, and select automatic save mode.

[0086] The camera setup steps are as follows: Set the image resolution to 1280*1024. Next, configure the camera exposure control: select manual exposure control, set the analog gain to 6x, the exposure time to 0.5s, and adjust the camera acquisition frame rate to the maximum. Once these settings are complete, adjust the aperture and focus using the two knobs on the front of the camera until the image is clear. This allows you to begin capturing images of the tire's trajectory on the road.

[0087] (3) The lateral force test vehicle is controlled at a speed of 50 km / h. At this time, the frame rate of the high-speed camera 8 reaches 1500 fps. The lateral force test vehicle is first raised to collect a set of blank background images, that is, the collected images only contain information of the regular texture road surface 14, excluding the tire 15. The test wheel of the lateral force test vehicle is lowered to make the tire 15 contact the road surface 14, and start collecting images of the tire 15 moving on the regular cross-section road surface 14.

[0088] (4) Obtaining tire envelope curve and road surface texture curve

[0089] All collected images are subjected to image tilt correction algorithm of MATLAB to detect image tilt angle and correct the images. The purpose is to transform the tilted images into images taken at the same level.

[0090] Using the tilt-corrected blank background image and the moving image, the tire envelope curve and the road surface texture curve are obtained according to the following steps.

[0091] 1) Read in a blank background image, convert the collected blank background image from an RGB image into a grayscale image through grayscale processing, use a filtering method to remove image noise, select a suitable threshold, convert the image into a black and white binary image, and then extract the surface texture contour edge information and the surface texture contour curve of the road surface.

[0092] 2) The image during motion is read in and subtracted from the background image to retain the tire status information and remove other parts of the image that affect the recognition result. The subtracted image is converted into a grayscale image and subjected to image noise reduction and threshold segmentation. The position information of the lowest point of the tire is then extracted from each processed motion image. The trajectory of the lowest point of the tire in each motion process is then fitted, and the fitting curve is used as the trajectory envelope curve of the tire moving on a regular cross-section road surface.

[0093] (5) Anti-skid index calculation and anti-skid performance evaluation based on tire envelope characteristics

[0094] Based on the road surface texture profile curve obtained in step 1) and the trajectory envelope curve obtained in step 2), the height difference between the arithmetic mean of the tire envelope curve and the arithmetic mean of the road surface texture profile curve is calculated as Δh. The size of Δh reflects the change in tire-road surface contact area under different conditions to characterize the anti-skid performance.

[0095] When the load increases, the envelope curve moves downward, Δh decreases, and the anti-skid performance increases; when the speed increases, the envelope curve moves upward, Δh increases, and the anti-skid performance decreases; when there is water, pollutants, ice and snow on the road, the envelope curve moves upward, Δh increases, and the anti-skid performance decreases, which is consistent with the actual situation.

[0096] In summary, the smaller the Δh value, the larger the contact area between the tire and the road surface, and the better the anti-skid performance. Conversely, the larger the Δh value, the smaller the contact area between the sliding part and the test piece, and the worse the anti-skid performance.

[0097] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should all be included in the scope of protection of the present invention.

Claims

1. A method for evaluating the anti-skid performance of a road surface based on envelope characteristics, characterized in that: The following steps are involved: 1) Collect the surface profile image of the test piece as a blank background image; 2) collecting the motion trajectory image of the sliding part on the test piece; 3) The blank background image is subjected to grayscale processing, filtering and denoising, and binarization processing in sequence to obtain a black and white binary background image, and the surface texture contour edge pixel information of the test piece is extracted from the black and white binary background image to obtain the surface texture contour curve of the test piece; 4) Subtracting the motion trajectory image obtained in step 2) from the blank background image in step 1), retaining the state information of the test piece, and obtaining a difference image; performing grayscale processing, noise reduction, and threshold segmentation on the difference image to obtain multiple motion images of the slider on the test piece; extracting the lowest point information of the slider from each motion image; performing trajectory fitting on the lowest point information of the slider during each motion process; and taking the fitting curve as the trajectory envelope curve of the slider on the test piece; 5) Calculate the arithmetic mean of the trajectory envelope curve in step 4) and the arithmetic mean of the surface texture profile curve in step 3), and define the height difference between the two arithmetic means as the anti-slip performance index Δh of the test piece. Evaluate the anti-slip performance between the sliding part and the test piece based on the size of Δh.

2. The method for evaluating the anti-skid performance of a road surface based on envelope characteristics according to claim 1, characterized in that: The steps 3), 4) and 5) are all completed by MATLAB.

3. The method for evaluating the anti-skid performance of a road surface based on envelope characteristics according to claim 1, characterized in that: The sliding member in step 2) is a rubber slider (12) or a tire (15); and the object to be tested in step 1) is a road surface (14) or a friction test piece (5).

4. The method for evaluating the anti-skid performance of a road surface based on envelope characteristics according to claim 3, characterized in that: In step 5), a smaller Δh value indicates a better anti-slip performance of the test piece, and conversely, a larger Δh value indicates a worse anti-slip performance of the test piece.

5. An evaluation device for implementing the method for evaluating road surface anti-skid performance based on envelope features as claimed in claim 4, characterized in that: The evaluation device comprises a base plate (1), a friction test piece (5), a rubber slider (12), a high-speed camera (8), a fixing fixture (2) and a pendulum instrument (4); the fixing fixture (2) is placed on the base plate (1), the friction test piece (5) is placed on the fixing fixture (2), the pendulum instrument (4) is placed above the fixing fixture (2) and connected to the base plate (1), the rubber slider (12) is placed on the pendulum instrument (4) and slides on the friction test piece (5); the high-speed camera (8) is connected to the base plate (1) and is located in front of the pendulum instrument (4).

6. The evaluation device according to claim 5, characterized in that The evaluation device comprises a fill light (6) placed on a bottom plate (1); the fill light (6) is located between a high-speed camera (8) and a pendulum instrument (4).

7. The evaluation device according to claim 6, wherein: The evaluation device further comprises a lifting mechanism connected to the base plate (1); the lifting mechanism comprises a lifting platform (9) and a lifting knob (10); the lifting platform (9) is connected to the base plate (1) via the lifting knob (10), and the lifting platform (9) moves up and down along the vertical direction of the base plate (1); the high-speed camera (8) is placed on the lifting platform (9).

8. The evaluation device according to claim 7, wherein: The evaluation device further comprises a computer (13) connected to the high-speed camera (8).

9. The evaluation device according to claim 8, characterized in that The evaluation device further comprises a pad (3) arranged on the base plate (1); a leveling knob (11) is arranged on the pad (3), and the leveling knob (11) is connected to the pendulum instrument (4).

10. An evaluation device for implementing the method for evaluating road surface anti-skid performance based on envelope characteristics as claimed in claim 4, characterized in that: The evaluation device comprises a high-speed camera (8), a fill light (6), a tire (15), a road surface (14) and a lateral force test vehicle; the lateral force test vehicle is placed on the road surface (14), the high-speed camera (8), the fill light (6) and the tire (15) are all placed on the lateral force test vehicle, and the high-speed camera (8) and the fill light (6) are both facing the hub surface of the tire (15).

Images