Road friction coefficient continuous measurement method, device, computer equipment and product
By applying a vertical load to the test trailer and controlling its uniform speed, the test tire is instantly locked, and the peak braking force and load are collected simultaneously to generate a friction coefficient distribution curve. This solves the problem of low detection efficiency in the existing technology, realizes continuous and automated measurement of road friction coefficient, and is suitable for unified evaluation under different environmental conditions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- QINGDAO PROD QUALITY INSPECTION INST (QINGDAO PROD QUALITY & SAFETY RISK MONITORING CENT)
- Filing Date
- 2026-04-07
- Publication Date
- 2026-06-09
AI Technical Summary
In existing technologies, the method for detecting the road friction coefficient is a single-point intermittent measurement, which cannot achieve long-distance continuous data collection, resulting in low detection efficiency and poor representativeness, making it difficult to meet the needs of modern rapid road detection and road network survey.
A method for continuous measurement of road friction coefficient is adopted. By applying a vertical load to a test trailer and controlling it to move at a constant speed on the road surface, the test tires are momentarily locked, and the peak braking force and vertical load are collected simultaneously. Combined with ambient temperature correction, a friction coefficient distribution curve is generated to achieve continuous measurement.
It enables continuous, long-distance, and automated measurement of road friction coefficient, improving detection efficiency, data accuracy and repeatability. It is suitable for unified evaluation under different environmental conditions and can identify the impact of road surface defects, ensuring test accuracy.
Smart Images
Figure CN122171441A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of road engineering testing technology, specifically relating to a method, device, computer equipment, and product for continuous measurement of road friction coefficient. Background Technology
[0002] The coefficient of friction is a core parameter for measuring the anti-skid performance of road surfaces, directly affecting vehicle braking distance, handling stability, and driving safety. Statistics show that approximately 20% of traffic accidents are related to insufficient friction due to slippery road surfaces, especially in rainy or snowy weather or on sharp curves, where a low coefficient of friction significantly increases the risk of skidding and rear-end collisions. Therefore, scientifically assessing the coefficient of friction and promptly identifying sections of road with deteriorating anti-skid performance are crucial for ensuring road traffic safety and optimizing maintenance decisions.
[0003] The current mainstream testing method is to use a pendulum friction coefficient meter (BPN). The principle is to release the pendulum from a fixed height and then slide it, measuring the sliding distance or energy loss, and then calculating the road surface friction coefficient. During the test, the vehicle must be stopped, the pendulum must be in vertical contact with the road surface, the data is recorded after release, and then the operation is repeated at the next measuring point. This method is simple to operate and low in cost, and is widely used for testing low-grade roads or local road sections. However, this method is a single-point intermittent measurement, which has the disadvantages of slow manual testing speed, low efficiency, poor representativeness of the tested road section, and inability to achieve long-distance continuous data collection. It is difficult to meet the needs of modern rapid road testing and road network survey.
[0004] Therefore, how to provide an effective solution to achieve continuous, long-distance, and automated measurement of road friction coefficient has become a pressing problem to be solved in existing technologies. Summary of the Invention
[0005] The purpose of this invention is to provide a method, apparatus, computer equipment, and product for continuous measurement of road friction coefficient, in order to solve the above-mentioned problems existing in the prior art.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for continuous measurement of road friction coefficient, comprising: When the test conditions are met, a specified vertical load is applied to the test tires mounted on the test trailer, and the test trailer is controlled to travel in a straight line at a specified speed on the test road surface. The test conditions include that the surface temperature of the test tires is the same as the ambient temperature and the tire pressure of the test tires is at a specified pressure. During the movement of the test trailer, the test tires were locked instantaneously multiple times according to preset locking conditions, and the peak braking force and vertical load of the test tires were collected simultaneously at each locking time. Based on the peak braking force and vertical load of the test tire during each locking, the road friction coefficient of the test tire during each locking is determined; Based on the road surface friction coefficient when the test tire is locked each time and the ambient temperature measured when the test tire is locked each time, the road surface friction coefficient of the test road surface at the specified ambient temperature is determined each time it is locked. Based on the distance traveled by the test trailer at each locking and the road surface friction coefficient of the test road surface at a specified ambient temperature at each locking, a friction coefficient distribution curve of the test road surface at a specified ambient temperature is generated.
[0007] In one possible design, the coefficient of friction of the test pavement at a specified ambient temperature during each locking is determined according to the following formula: μ ti =μ i +k×(tT i ); Where, μ i The road surface friction coefficient is represented by k, the temperature correction coefficient is represented by t, and the specified ambient temperature is represented by T. i μ represents the ambient temperature measured during the i-th locking event. ti This represents the coefficient of friction of the test pavement at a specified ambient temperature during the i-th locking event.
[0008] In one possible design, the test trailer travels at a speed of 1 m / s to 2 m / s on the test surface, the vertical load applied to the test tire is 50 kg, and the specified pressure is 220 kPa.
[0009] In one possible design, the preset locking condition is to perform an instantaneous lock every preset travel distance or every preset travel time.
[0010] In one possible design, the method further includes: Acquire multiple consecutive frames of images captured by the camera before each locking of the test tire to obtain an image sequence corresponding to each locking. For each image sequence, each frame in the image sequence is converted into a grayscale image to obtain a grayscale image sequence corresponding to each locking. Linear stretching of the grayscale values of each grayscale image sequence yields the processed grayscale image sequence corresponding to each locking action. Threshold segmentation is performed on the processed grayscale images in each processed grayscale image sequence based on the maximum inter-class variance method to obtain the binary image sequence corresponding to each locking. For each binary image in each binary image sequence, the pixel values of the pixels in the binary image are projected horizontally and vertically to obtain the pixel horizontal projection distribution and pixel vertical projection distribution of each binary image in each binary image sequence. Based on the horizontal and vertical pixel projection distributions of each binary image in each binary image sequence, the pavement defect identification result corresponding to each binary image in each binary image sequence is determined. The pavement defect identification result indicates whether the corresponding test pavement has defects or not. The defects are either cracks or potholes in the corresponding test pavement. When the pavement distress identification result corresponding to at least one binary image in any binary image sequence is that there is distress on the corresponding test pavement, the pavement friction coefficient of a certain locked pavement corresponding to any binary image sequence is determined to be an invalid pavement friction coefficient.
[0011] In one possible design, based on the horizontal and vertical pixel projection distributions of each binary image in each binary image sequence, the pavement defect identification result corresponding to each binary image in each binary image sequence is determined, including: If there are K1 consecutive pixels whose pixel projection values are greater than a preset threshold in the horizontal projection distribution of a binary image, and K2 consecutive pixels whose pixel projection values are greater than a preset threshold in the vertical projection distribution of a binary image, then the road surface defect identification result corresponding to the binary image is determined to be that there are cracks in the corresponding test road surface. If there are K2 consecutive pixels whose pixel projection values are greater than a preset threshold in the horizontal projection distribution of a binary image, and K1 consecutive pixels whose pixel projection values are greater than a preset threshold in the vertical projection distribution of a binary image, then the road surface defect identification result corresponding to the binary image is determined to be that there are cracks in the corresponding test road surface. If there are K2 consecutive pixels whose horizontal projection values are greater than a preset threshold in the pixel horizontal projection distribution of a binary image, and there are K2 consecutive pixels whose vertical projection values are greater than a preset threshold in the pixel vertical projection distribution of a binary image, then the road surface defect identification result corresponding to the binary image is determined to be that there are potholes on the corresponding test road surface. Where K1 < K2.
[0012] In one possible design, the gray levels of each grayscale image sequence are linearly stretched according to the following formula to obtain the processed grayscale image sequence corresponding to each locking. ; in, This represents the grayscale value of the pixel with coordinates (i, j) in the processed grayscale image. This represents the grayscale value of the pixel at coordinates (i, j) in a grayscale image. This represents the maximum grayscale value in a grayscale image. This represents the minimum grayscale value in a grayscale image. This indicates the maximum grayscale value allowed to be output from the processed grayscale image. This indicates the minimum grayscale value that the processed grayscale image is allowed to output.
[0013] Secondly, the present invention provides a continuous road friction coefficient measuring device, comprising: The travel control unit is used to apply a specified vertical load to the test tire mounted on the test trailer when the test conditions are met, and to control the test trailer to travel in a straight line at a specified speed on the test road surface. The test conditions include the surface temperature of the test tire being the same as the ambient temperature and the tire pressure of the test tire being at a specified pressure. The locking and acquisition unit is used to lock the test tire multiple times instantaneously according to preset locking conditions during the movement of the test trailer, and simultaneously acquire the peak braking force and vertical load of the test tire at each locking. The first determining unit is used to determine the road friction coefficient of the test tire each time it is locked, based on the peak braking force and vertical load of the test tire each time it is locked. The second determining unit is used to determine the road surface friction coefficient of the test road surface at a specified ambient temperature each time the test tire is locked, based on the road surface friction coefficient when the test tire is locked each time and the ambient temperature measured when the test tire is locked each time. The generation unit is used to generate a friction coefficient distribution curve of the test road surface at a specified ambient temperature based on the travel distance of the test trailer at each locking and the road surface friction coefficient of the test road surface at a specified ambient temperature at each locking.
[0014] Thirdly, the present invention provides a computer device comprising a memory, a processor, and a transceiver connected in sequence and communication, wherein the memory is used to store a computer program, the transceiver is used to send and receive messages, and the processor is used to read the computer program and execute the continuous measurement method for road friction coefficient as described in the first aspect or any possible design of the first aspect.
[0015] Fourthly, the present invention provides a computer-readable storage medium storing instructions that, when executed on a computer, perform the continuous road friction coefficient measurement method described in the first aspect or any possible design of the first aspect.
[0016] Fifthly, the present invention provides a computer program product containing instructions that, when executed on a computer, cause the computer to perform the continuous measurement method for road friction coefficient as described in the first aspect or any possible design of the first aspect.
[0017] Beneficial effects: This invention provides a continuous measurement scheme for road friction coefficient, which can realize continuous, long-distance, and automated measurement of road friction coefficient. Specifically, when the test conditions are met, a specified vertical load is applied to the test tire mounted on the test trailer, and the test trailer is controlled to travel in a straight line at a specified speed on the test road surface. The test conditions include the surface temperature of the test tire being the same as the ambient temperature and the tire pressure being at a specified pressure. During the movement of the test trailer, the test tire is momentarily locked multiple times according to preset locking conditions, and the peak braking force and vertical load of the test tire are collected simultaneously at each locking point. Based on the peak braking force and vertical load of the test tire at each locking point, the road surface friction coefficient of the test tire at each locking point is determined. Based on the road surface friction coefficient of the test tire at each locking point and the ambient temperature measured at each locking point, the road surface friction coefficient of the test road surface at the specified ambient temperature at each locking point is determined. Based on the travel distance of the test trailer at each locking point and the road surface friction coefficient of the test road surface at the specified ambient temperature at each locking point, a friction coefficient distribution curve of the test road surface at the specified ambient temperature is generated. In this way, by controlling the test trailer to travel at a constant speed in a straight line, and locking it instantaneously during the journey while simultaneously collecting the peak braking force and vertical load of the test tires, the road friction coefficient at each lock is determined. Combined with the detected temperature, the road friction coefficient is corrected, generating a friction coefficient distribution curve of the test road surface under a specified ambient temperature. This enables continuous, long-distance, and automated measurement of the road friction coefficient, improving testing efficiency. At the same time, the test process is standardized and easy to operate, and can be widely used in road acceptance and maintenance testing. In addition, it has a temperature correction function, making it suitable for unified evaluation under different environmental conditions. Furthermore, the parameters of the entire test process are standardized, and the data is accurate, repeatable, and highly comparable.
[0018] Furthermore, image recognition can be used to identify pavement defects on the test pavement before each locking. When defects are identified on the corresponding test pavement, the pavement friction coefficient of that locking is determined as an invalid pavement friction coefficient, thereby eliminating the impact of defects such as cracks or potholes on the accuracy of pavement friction coefficient testing. Attached Figure Description
[0019] Figure 1 A flowchart illustrating the continuous measurement method for road friction coefficient provided in this application embodiment; Figure 2A block diagram of the road friction coefficient continuous measurement device provided in the embodiments of this application; Figure 3 This is a block diagram of a computer device provided in an embodiment of this application. Detailed Implementation
[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in conjunction with the accompanying drawings and descriptions of the embodiments or the prior art. Obviously, the following description of the structure of the accompanying drawings is only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.
[0021] Example: This embodiment discloses a method for continuous measurement of road friction coefficient, which can be executed, but is not limited to, by a computer device or virtual machine with certain computing resources, such as by an electronic device such as a personal computer, smartphone, personal digital assistant or wearable device, or by a virtual machine.
[0022] like Figure 1 The diagram shown is a flowchart of a method for continuously measuring the road friction coefficient provided in an embodiment of this application. This method may include, but is not limited to, the following steps S101-S105.
[0023] Step S101. When the test conditions are met, apply a specified vertical load to the test tires mounted on the test trailer, and control the test trailer to travel in a straight line at a specified speed on the test road surface.
[0024] The test conditions include the surface temperature of the test tire being the same as the ambient temperature and the tire pressure of the test tire being at a specified pressure.
[0025] In one or more embodiments, the test tire may be an ASTM F2493 standard reference test tire with specifications of P225 / 60R16 97S. Before measuring the road friction coefficient, the test tire may be left to stand in the test environment for no less than 2 hours to allow the surface temperature of the test tire to match the ambient temperature. At the same time, the tire pressure of the test tire should be precisely adjusted to the specified pressure, which is generally 220 kPa.
[0026] The test tire is mounted on a test trailer, which can be equipped with a brake locking mechanism, pressure sensor, load measurement unit, and temperature sensor, which can be used to momentarily lock the test tire, measure the peak braking force of the test tire when locked, measure the vertical load of the test tire when locked, and measure the ambient temperature when locked, respectively.
[0027] Before measuring the road friction coefficient, the test surface must be cleaned to remove debris and loose particles, creating a wet road surface test condition according to the testing requirements. During measurement, a specified vertical load can be applied to the test tires mounted on the test trailer, and the test trailer is controlled to travel in a straight line at a specified speed on the test surface. The applied vertical load can be set according to the actual situation; for example, the applied vertical load can be 50 kg, and the travel speed of the test trailer on the test surface can be 1 m / s-2 m / s.
[0028] Step S102. During the movement of the test trailer, the test tire is locked momentarily multiple times according to the preset locking conditions, and the peak braking force and vertical load of the test tire are collected simultaneously at each locking.
[0029] The locking conditions can be determined according to the actual situation. For example, it can be a momentary lock every preset travel distance, a momentary lock every preset travel time, or a momentary lock based on the set travel distance.
[0030] Each time the test tire is momentarily locked, the peak braking force and vertical load of the test tire can be collected simultaneously, along with the ambient temperature.
[0031] Step S103. Based on the peak braking force and vertical load of the test tire during each locking, determine the road friction coefficient of the test tire during each locking.
[0032] The road surface friction coefficient can be expressed as μ i =F i / N i ), where μ i F represents the coefficient of friction of the road surface when the tire is locked in the i-th test. i N represents the peak braking force of the test tire during the i-th locking event. i This represents the vertical load on the test tire during the i-th locking phase.
[0033] Step S104. Based on the road surface friction coefficient when the test tire is locked each time and the ambient temperature measured when the test tire is locked each time, determine the road surface friction coefficient of the test road surface at the specified ambient temperature when locked each time.
[0034] In one or more embodiments, the coefficient of friction of the test surface at a specified ambient temperature during each locking can be determined according to the following formula: μ ti =μ i +k×(tT i ); Where, μ i The road surface friction coefficient is represented by k at the i-th locking point, k represents the temperature correction coefficient (which can be determined through experimental calibration), and t represents the specified ambient temperature. i μ represents the ambient temperature measured during the i-th locking event. ti This represents the coefficient of friction of the test pavement at a specified ambient temperature during the i-th locking event.
[0035] Step S105. Based on the travel distance of the test trailer during each locking and the road surface friction coefficient of the test road surface at the specified ambient temperature during each locking, generate the friction coefficient distribution curve of the test road surface at the specified ambient temperature.
[0036] During the road friction coefficient test, the road surface may have defects such as cracks or potholes. In order to avoid the impact of defects such as cracks or potholes on the accuracy of the road friction coefficient test, in one or more embodiments, the road friction coefficient measured when the road surface has just passed through the defect can be determined as an invalid road friction coefficient, and the road friction coefficient measured when the road surface has passed through the normal road surface can be retained, so as to eliminate the influence of defects such as cracks or potholes on the accuracy of the road friction coefficient test. This may include, but is not limited to, the following steps S201-S207.
[0037] Step S201. Acquire multiple consecutive frames of test road surface images captured by the camera before each locking of the test tire, and obtain the image sequence corresponding to each locking.
[0038] In one or more embodiments, a camera can be mounted on a test trailer to capture images of the test road surface. During continuous measurement of the road friction coefficient, multiple consecutive frames of images of the test road surface captured by the camera before each locking of the test tire can be obtained, resulting in an image sequence corresponding to each locking.
[0039] Step S202. For each image sequence, convert each frame of the image sequence into a grayscale image to obtain a grayscale image sequence corresponding to each locking.
[0040] Step S203. Linearly stretch the grayscale of each grayscale image sequence to obtain the processed grayscale image sequence corresponding to each locking.
[0041] In one or more embodiments, the grayscale of each grayscale image sequence can be linearly stretched according to the following formula to obtain the processed grayscale image sequence corresponding to each locking. ; in, This represents the grayscale value of the pixel with coordinates (i, j) in the processed grayscale image. This represents the grayscale value of the pixel at coordinates (i, j) in a grayscale image. This represents the maximum grayscale value in a grayscale image. This represents the minimum grayscale value in a grayscale image. This indicates the maximum grayscale value allowed to be output from the processed grayscale image. This indicates the minimum grayscale value that the processed grayscale image is allowed to output.
[0042] Step S204. Threshold segmentation is performed on the processed grayscale images in each processed grayscale image sequence based on the Otsu's method to obtain the binary image sequence corresponding to each locking.
[0043] Step S205. For each binary image in each binary image sequence, perform horizontal and vertical projection on the pixel values of the pixels in the binary image to obtain the horizontal and vertical projection distribution of pixels in each binary image in each binary image sequence.
[0044] When performing horizontal projection, the pixel values (binarized values) of all pixels at the same horizontal coordinate in a binary image are superimposed to obtain the horizontal projection distribution of pixels in the binary image. When performing vertical projection, the pixel values (binarized values) of all pixels at the same vertical coordinate in a binary image are superimposed to obtain the vertical projection distribution of pixels in the binary image.
[0045] Step S206. Based on the horizontal and vertical pixel projection distributions of each binary image in each binary image sequence, determine the pavement defect identification result corresponding to each binary image in each binary image sequence. The pavement defect identification result is whether the corresponding test pavement has defects or not. The defects are either cracks or potholes in the corresponding test pavement.
[0046] Specifically, if there are K1 consecutive pixels whose pixel projection values are greater than a preset threshold in the horizontal projection distribution of a binary image, and K2 consecutive pixels whose pixel projection values are greater than a preset threshold in the vertical projection distribution of a binary image, then the road surface defect identification result corresponding to the binary image is determined to be that there are cracks in the corresponding test road surface. If there are K2 consecutive pixels whose pixel projection values are greater than a preset threshold in the horizontal projection distribution of a binary image, and K1 consecutive pixels whose pixel projection values are greater than a preset threshold in the vertical projection distribution of a binary image, then the road surface defect identification result corresponding to the binary image is determined to be that there are cracks in the corresponding test road surface. If there are K2 consecutive pixels whose horizontal projection values are greater than a preset threshold in the pixel horizontal projection distribution of a binary image, and there are K2 consecutive pixels whose vertical projection values are greater than a preset threshold in the pixel vertical projection distribution of a binary image, then the road surface defect identification result corresponding to the binary image is determined to be that there are potholes on the corresponding test road surface. Where K1 and K2 are both positive integers, and K1 < K2.
[0047] Step S207. When the pavement distress identification result corresponding to at least one binary image in any binary image sequence is that there is distress on the corresponding test pavement, the pavement friction coefficient of a certain locked pavement corresponding to any binary image sequence is determined as an invalid pavement friction coefficient.
[0048] In summary, the continuous road friction coefficient measurement method provided by this invention applies a specified vertical load to a test tire mounted on a test trailer when the test conditions are met, and controls the test trailer to travel in a straight line at a specified speed on the test road surface. The test conditions include the surface temperature of the test tire being the same as the ambient temperature and the tire pressure being at a specified pressure. During the movement of the test trailer, the test tire is locked instantaneously multiple times according to preset locking conditions, and the peak braking force and vertical load of the test tire at each locking are simultaneously collected. Based on the peak braking force and vertical load of the test tire at each locking, the road friction coefficient of the test tire at each locking is determined. Based on the road friction coefficient of the test tire at each locking and the ambient temperature measured at each locking, the road friction coefficient of the test road surface at each locking at a specified ambient temperature is determined. Based on the travel distance of the test trailer at each locking and the road friction coefficient of the test road surface at each locking at a specified ambient temperature, a friction coefficient distribution curve of the test road surface at a specified ambient temperature is generated. In this way, by controlling the test trailer to travel at a constant speed in a straight line, and momentarily locking it during the journey while simultaneously collecting the peak braking force and vertical load of the test tires, the road surface friction coefficient at each lock is determined. This coefficient is then corrected based on the detected temperature, generating a friction coefficient distribution curve for the test road surface under a specified ambient temperature. This enables continuous, long-distance, and automated measurement of the road friction coefficient, improving testing efficiency. Simultaneously, the test conditions are realistic, the results more consistent with actual road use, the test process is standardized and easy to operate, and it can be widely applied to road acceptance and maintenance inspections. Furthermore, it has a temperature correction function, suitable for unified evaluation under different environmental conditions. In addition, the parameters throughout the testing process are standardized, ensuring accurate, repeatable, and highly comparable data. Finally, image recognition can be used to identify road surface defects before each lock. When defects are identified in the corresponding test road surface, the road surface friction coefficient for that lock is determined as invalid, thus eliminating the impact of defects such as cracks or potholes on the accuracy of the road friction coefficient test.
[0049] Please see Figure 2 The second aspect of this application provides a continuous road friction coefficient measuring device, which includes: The travel control unit is used to apply a specified vertical load to the test tire mounted on the test trailer when the test conditions are met, and to control the test trailer to travel in a straight line at a specified speed on the test road surface. The test conditions include the surface temperature of the test tire being the same as the ambient temperature and the tire pressure of the test tire being at a specified pressure. The locking and acquisition unit is used to lock the test tire multiple times instantaneously according to preset locking conditions during the movement of the test trailer, and simultaneously acquire the peak braking force and vertical load of the test tire at each locking. The first determining unit is used to determine the road friction coefficient of the test tire each time it is locked, based on the peak braking force and vertical load of the test tire each time it is locked. The second determining unit is used to determine the road surface friction coefficient of the test road surface at a specified ambient temperature each time the test tire is locked, based on the road surface friction coefficient when the test tire is locked each time and the ambient temperature measured when the test tire is locked each time. The generation unit is used to generate a friction coefficient distribution curve of the test road surface at a specified ambient temperature based on the travel distance of the test trailer at each locking and the road surface friction coefficient of the test road surface at a specified ambient temperature at each locking.
[0050] The working process, working details and technical effects of the road friction coefficient continuous measuring device provided in the second aspect of this embodiment can be found in the first aspect of the embodiment, and will not be repeated here.
[0051] Please see Figure 3 The third aspect of this application provides a computer device including a memory, a processor, and a transceiver that are sequentially and communicatively connected, wherein the memory is used to store a computer program, the transceiver is used to send and receive messages, and the processor is used to read the computer program and execute the continuous road friction coefficient measurement method as described in the first aspect of the application.
[0052] Specifically, the memory may include, but is not limited to, random access memory (RAM), read-only memory (ROM), flash memory, first-in-first-out (FIFO) memory, and / or last-in-first-out (FILO) memory, etc.; the processor may not be limited to microprocessors of the STM32F105 series, ARM (Advanced RISC Machines), x86 architecture processors, or processors with integrated NPU (neural-network processing units); the transceiver may be, but is not limited to, WiFi (Wireless Fidelity) wireless transceivers, Bluetooth wireless transceivers, General Packet Radio Service (GPRS) wireless transceivers, ZigBee (a low-power LAN protocol based on the IEEE 802.15.4 standard), 3G transceivers, 4G transceivers, and / or 5G transceivers, etc.
[0053] This fourth aspect of the embodiment provides a computer-readable storage medium storing instructions comprising the road friction coefficient continuous measurement method described in the first aspect of the embodiment. Specifically, the computer-readable storage medium stores instructions that, when executed on a computer, perform the road friction coefficient continuous measurement method as described in the first aspect. The computer-readable storage medium refers to a data storage medium, which may include, but is not limited to, floppy disks, optical disks, hard disks, flash memory, USB flash drives, and / or memory sticks. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.
[0054] The fifth aspect of this embodiment provides a computer program product containing instructions that, when executed on a computer, cause the computer to perform the continuous road friction coefficient measurement method as described in the first aspect of the embodiment, wherein the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device.
[0055] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for continuous measurement of road friction coefficient, characterized in that, include: When the test conditions are met, a specified vertical load is applied to the test tires mounted on the test trailer, and the test trailer is controlled to travel in a straight line at a specified speed on the test road surface. The test conditions include that the surface temperature of the test tires is the same as the ambient temperature and the tire pressure of the test tires is at a specified pressure. During the movement of the test trailer, the test tires were locked instantaneously multiple times according to preset locking conditions, and the peak braking force and vertical load of the test tires were collected simultaneously at each locking time. Based on the peak braking force and vertical load of the test tire during each locking, the road friction coefficient of the test tire during each locking is determined. Based on the road surface friction coefficient when the test tire is locked each time and the ambient temperature measured when the test tire is locked each time, the road surface friction coefficient of the test road surface at the specified ambient temperature is determined each time it is locked. Based on the distance traveled by the test trailer at each locking and the road surface friction coefficient of the test road surface at a specified ambient temperature at each locking, a friction coefficient distribution curve of the test road surface at a specified ambient temperature is generated.
2. The method for continuous measurement of road friction coefficient according to claim 1, characterized in that, The coefficient of friction of the test surface at a specified ambient temperature during each locking is determined using the following formula: m ti =m i +k×(tT i ); Where, μ i The road surface friction coefficient is represented by k, the temperature correction coefficient is represented by t, and the specified ambient temperature is represented by T. i μ represents the ambient temperature measured during the i-th locking event. ti This represents the coefficient of friction of the test pavement at a specified ambient temperature during the i-th locking event.
3. The method for continuous measurement of road friction coefficient according to claim 1, characterized in that, The test trailer travels at a speed of 1m / s-2m / s on the test surface, the vertical load applied to the test tire is 50kg, and the specified pressure is 220kPa.
4. The method for continuous measurement of road friction coefficient according to claim 1, characterized in that, The preset locking condition is to lock momentarily every preset travel distance or every preset travel time.
5. The method for continuous measurement of road friction coefficient according to claim 1, characterized in that, The method further includes: Acquire multiple consecutive frames of images of the test road surface captured by the camera before each locking of the test tire, and obtain the image sequence corresponding to each locking. For each image sequence, each frame in the image sequence is converted into a grayscale image to obtain a grayscale image sequence corresponding to each locking. Linear stretching of the grayscale values of each grayscale image sequence yields the processed grayscale image sequence corresponding to each locking action. Threshold segmentation is performed on the processed grayscale images in each processed grayscale image sequence based on the maximum inter-class variance method to obtain the binary image sequence corresponding to each locking. For each binary image in each binary image sequence, the pixel values of the pixels in the binary image are projected horizontally and vertically to obtain the pixel horizontal projection distribution and pixel vertical projection distribution of each binary image in each binary image sequence. Based on the horizontal and vertical pixel projection distributions of each binary image in each binary image sequence, the pavement defect identification result corresponding to each binary image in each binary image sequence is determined. The pavement defect identification result indicates whether the corresponding test pavement has defects or not. The defects are either cracks or potholes in the corresponding test pavement. When the pavement distress identification result corresponding to at least one binary image in any binary image sequence is that there is distress on the corresponding test pavement, the pavement friction coefficient of a certain locked pavement corresponding to any binary image sequence is determined to be an invalid pavement friction coefficient.
6. The method for continuous measurement of road friction coefficient according to claim 5, characterized in that, Based on the horizontal and vertical pixel projection distributions of each binary image in each binary image sequence, the pavement defect identification results corresponding to each binary image in each binary image sequence are determined, including: If there are K1 consecutive pixels whose pixel projection values are greater than a preset threshold in the horizontal projection distribution of a binary image, and K2 consecutive pixels whose pixel projection values are greater than a preset threshold in the vertical projection distribution of a binary image, then the road surface defect identification result corresponding to the binary image is determined to be that there are cracks in the corresponding test road surface. If there are K2 consecutive pixels whose pixel projection values are greater than a preset threshold in the horizontal projection distribution of a binary image, and K1 consecutive pixels whose pixel projection values are greater than a preset threshold in the vertical projection distribution of a binary image, then the road surface defect identification result corresponding to the binary image is determined to be that there are cracks in the corresponding test road surface. If there are K2 consecutive pixels whose horizontal projection values are greater than a preset threshold in the pixel horizontal projection distribution of a binary image, and there are K2 consecutive pixels whose vertical projection values are greater than a preset threshold in the pixel vertical projection distribution of a binary image, then the road surface defect identification result corresponding to the binary image is determined to be that there are potholes on the corresponding test road surface. Where K1 < K2.
7. The method for continuous measurement of road friction coefficient according to claim 5, characterized in that, The gray levels of each grayscale image sequence are linearly stretched according to the following formula to obtain the processed grayscale image sequence corresponding to each locking. ； in, This represents the grayscale value of the pixel with coordinates (i, j) in the processed grayscale image. This represents the grayscale value of the pixel at coordinates (i, j) in a grayscale image. This represents the maximum grayscale value in a grayscale image. This represents the minimum grayscale value in a grayscale image. This indicates the maximum grayscale value allowed to be output from the processed grayscale image. This indicates the minimum grayscale value that the processed grayscale image is allowed to output.
8. A continuous measuring device for road friction coefficient, characterized in that, include: The travel control unit is used to apply a specified vertical load to the test tire mounted on the test trailer when the test conditions are met, and to control the test trailer to travel in a straight line at a specified speed on the test road surface. The test conditions include the surface temperature of the test tire being the same as the ambient temperature and the tire pressure of the test tire being at a specified pressure. The locking and acquisition unit is used to lock the test tire multiple times instantaneously according to preset locking conditions during the movement of the test trailer, and simultaneously acquire the peak braking force and vertical load of the test tire at each locking. The first determining unit is used to determine the road friction coefficient of the test tire each time it is locked, based on the peak braking force and vertical load of the test tire each time it is locked. The second determining unit is used to determine the road surface friction coefficient of the test road surface at a specified ambient temperature each time the test tire is locked, based on the road surface friction coefficient when the test tire is locked each time and the ambient temperature measured when the test tire is locked each time. The generation unit is used to generate a friction coefficient distribution curve of the test road surface at a specified ambient temperature based on the travel distance of the test trailer at each locking and the road surface friction coefficient of the test road surface at a specified ambient temperature at each locking.
9. A computer device, characterized in that, The device includes a memory, a processor, and a transceiver that are sequentially and communicatively connected. The memory is used to store a computer program, the transceiver is used to send and receive messages, and the processor is used to read the computer program and execute the continuous measurement method for road friction coefficient as described in any one of claims 1 to 7.
10. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or the instructions are executed by the computer, they implement the continuous measurement method for road friction coefficient as described in any one of claims 1 to 7.