A method and system for evaluating the friction coefficient between automobile tires and road surfaces in a rainy environment

Abstract

The present invention discloses a method for evaluating the friction coefficient between automobile tires and road surfaces in a rainy environment, comprising the following steps: S1, automatically obtaining road geometry feature information of the tested road section and drainage capacity information of drainage facilities; S2, automatically obtaining rainfall intensity information of the tested road section; S3, calculating the friction coefficient between tires and road surfaces under different road sections and different rainfall intensity combinations according to the road geometry feature information and drainage capacity information obtained in step S1 and the rainfall intensity information obtained in step S2. The present invention also discloses a system for evaluating the friction coefficient between automobile tires and road surfaces in a rainy environment. The method and system of the present invention do not require any on-site equipment, and can quantitatively analyze the influence of rainfall intensity on the friction coefficient of road surfaces under different road geometry features by only relying on data obtained by a weather radar installed on the roadside, thereby solving the problem of complex procedures, low precision and poor repeatability in on-site measurement of road friction coefficient in a rainy environment.

Description

Technical Field

[0001] The invention belongs to the technical field of traffic safety, and in particular relates to a method and a system for evaluating the friction coefficient between a car tire and a road surface in a rainy environment. Background Art

[0002] Identifying the impact of rain on the friction coefficient between car tires and the road is one of the key technical problems that must be solved first to achieve safe all-weather passage on smart highways. Accurately and quickly evaluating the friction coefficient between car tires and the road in a rainy environment is a practical need to ensure the safety of smart highway operations and formulate speed limit plans. The most direct impact of rainfall on vehicle driving safety is that the increase in the thickness of the road water film caused by rainfall leads to a decrease in the friction coefficient of the road surface, which weakens the anti-skid performance of the road surface and easily leads to side slip, side sliding and collision accidents.

[0003] Most existing technologies use simulation and field measurements to quantify the impact of rainfall on the friction coefficient of the road surface by using the thickness of the water film. This is consistent with the mechanism of rainfall on the friction coefficient of the road surface, that is, the impact of rainfall on the friction coefficient is due to the thickness of the water film brought by rainfall, which causes the interaction characteristics between the tire and the road surface to change. However, for users, it is necessary to measure the thickness of the water film (water accumulation) on the road surface on-site in a rainy environment to clarify the impact of rainfall on the driving environment. This method is complicated, difficult to ensure accuracy, and has poor repeatability, which undoubtedly limits the promotion and application of the results. The driving environment of a highway in a rainy environment is a complex system. Different road geometric characteristics and drainage capacity of drainage facilities have different effects on the thickness of the water film on the road surface, which increases the complexity of the evaluation of rainfall on the friction coefficient of the road surface. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for evaluating the friction coefficient between automobile tires and roads in a rainy environment. The present invention is suitable for quickly evaluating the friction coefficient between automobile tires and roads in a rainy environment, so as to solve the problem that it is difficult to accurately measure the water film thickness using the existing technology, and the inaccuracy of directly using the water film thickness to predict the friction coefficient.

[0005] A first object of the present invention is to provide a method for evaluating the friction coefficient between a vehicle tire and a road surface in a rainy environment, comprising the following steps:

[0006] S1. Obtaining road geometry information of the tested road section and drainage capacity information of drainage facilities;

[0007] S2. Obtaining rainfall intensity information of the tested road section;

[0008] S3. Calculate the friction coefficient between the tire and the road under different road sections and different combinations of rainfall intensities based on the road geometry information and drainage capacity information obtained in step S1 and the rainfall intensity information obtained in step S2.

[0009] Preferably, in step S3, the calculation of the friction coefficient includes the following steps:

[0010] S31, calculating rainfall and drainage according to the rainfall intensity information obtained in step S2;

[0011] S32, calculating the amount of water accumulation under different road geometric characteristics based on the road geometric characteristic information obtained in step S1 and the rainfall and drainage calculated in step S31;

[0012] S33. Calculate the friction coefficient between the tire and the road surface under different rainfall intensities according to the drainage capacity information obtained in step S1 and the amount of accumulated water calculated in step S32 to obtain the friction coefficient between the tire and the road surface.

[0013] Preferably, in step S31, the calculation formula of the rainfall is as follows:

[0014] Q=I R LW×10 -3

[0015] Among them, Q represents the rainfall in the confluence area of ​​the tested road section, which is related to the composite slope of the road and the drainage facilities. R It represents rainfall intensity, L represents drainage length parallel to driving direction, and W represents road width.

[0016] Preferably, in step S32, when a curbstone is provided at the outer edge of the hard shoulder of the road, the calculation formula of the drainage volume is as follows:

[0017]

[0018] Among them, Q c Indicates the displacement, i h represents the transverse slope, n represents the roughness coefficient of the asphalt pavement, H represents the water film thickness, and I represents the longitudinal slope.

[0019] Preferably, in step S33, the friction coefficient model is:

[0020] f=a1H 3 +a2H 2 +a3H+C

[0021] Among them, f is the road friction coefficient, H is the water film thickness, a1, a2, a3, and C are constants.

[0022] The second object of the present invention is to provide a system for evaluating the friction coefficient between automobile tires and road surfaces in a rainy environment, comprising a weather information processing module, a road information processing module, a drainage facility capacity analysis module, a friction coefficient model calculation module and an information display module;

[0023] The weather information processing module is used to process weather forecast information, information input by users, and information collected by roadside meteorological equipment;

[0024] The road information processing module is used for multi-source heterogeneous information processing and obtaining road geometric features, road surface characteristics, and service life information;

[0025] The drainage facility capacity analysis module is used for image recognition, analysis, judgment and evaluation of the use status of drainage facilities;

[0026] The friction coefficient model calculation module is used to calculate the friction coefficient between the automobile tire and the road surface in a rainy environment based on weather information, road information, and drainage facility capacity information;

[0027] The information display module is used to display the friction coefficient data between the automobile tire and the road surface.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention provides a system for evaluating the friction coefficient between automobile tires and road surfaces under rainfall conditions, which can obtain road geometry information and drainage capacity information of the tested road section, obtain rainfall intensity information of the tested road section with the help of roadside meteorological radar, and directly and quickly predict the friction coefficient between tires and road surfaces under different road sections and different rainfall intensity combinations based on the rainfall intensity information, road geometry information and drainage capacity information of drainage facilities, thereby solving the technical problems of difficulty in real-time dynamic measurement of road friction coefficient and inaccurate measurement on rainy days;

[0030] (2) The method and system for evaluating the friction coefficient between automobile tires and road surfaces in a rainy environment provided by the present invention can quickly evaluate the impact of rainfall on the friction coefficient between tires and road surfaces, quickly formulate a reasonable speed limit plan for rainy days, and provide a basis for formulating an all-weather rapid and safe passage strategy. It has huge economic benefits for ensuring all-weather rapid passage on China's current 160,000 kilometers of expressways; it has good social benefits for achieving all-weather safe passage on rainy expressways. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A flowchart of a method for evaluating the friction coefficient between a vehicle tire and a road surface in a rainy environment provided by an embodiment of the present invention;

[0032] Figure 2 It is a flowchart of the friction coefficient model calculation principle in the embodiment of the present invention;

[0033] Figure 3 A structural block diagram of a system for evaluating the friction coefficient between a vehicle tire and a road surface in a rainy environment provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0035] like Figure 1 As shown, the method for evaluating the friction coefficient between a car tire and a road surface in a rainy environment provided by an embodiment of the present invention specifically includes the following steps:

[0036] S1. Obtaining road geometry feature information of the tested road section and drainage capacity information of drainage facilities; specifically, using the road information processing module and drainage facility capacity analysis module in the system for evaluating the friction coefficient between automobile tires and road surfaces under rainy conditions provided by the embodiment of the present invention to obtain the longitudinal slope I and transverse slope i of the tested road section through image recognition and reading the road section design and management database. h , road width W, road surface type, construction depth, service life, drainage facility type and geometric dimensions, etc. If the user does not have a database, the system can manually input the above data;

[0037] S2. Obtaining rainfall intensity information of the tested section; the system provided by the embodiment of the present invention has three methods to obtain the rainfall intensity I of the tested section. R , first, according to the weather forecast, second, according to the roadside meteorological information collection device, and third, through field measurement, the standard artificial rain gauge is selected for field measurement. In order to ensure rapidity, the system can calculate the hourly rainfall intensity based on the measured rainfall intensity of 15 minutes. According to the weather forecast or the field measurement of the rainfall intensity of 15 minutes, the range of friction coefficient changes under different rainfall intensities (weather forecast) or the accurate friction coefficient (field measurement) can be evaluated;

[0038] S3, based on the road geometry information and drainage capacity information obtained in step S1 and the rainfall intensity information I obtained in step S2 R The friction coefficient between the tire and the road surface under different road sections and different rainfall intensity combinations is calculated, such as Figure 2 As shown, the calculation of the friction coefficient includes the following steps:

[0039] S31, calculating rainfall and drainage according to the rainfall intensity information obtained in step S2;

[0040] S32. Calculate the amount of water accumulation under different road geometric characteristics based on the road geometric characteristic information obtained in step S1 in combination with the rainfall and drainage calculated in step S31; the transverse and longitudinal slopes of the road surface are different, and the road drainage capacity is different. There are situations where the transverse drainage of the road is poor, the longitudinal drainage is poor, or both the transverse and longitudinal drainage are poor. Rainfall cannot be discharged from the road surface in time, and water accumulates. The calculation model of the water accumulation is determined according to the road geometric characteristics.

[0041] S33, calculating the friction coefficient between the tire and the road surface under different rainfall intensities based on the drainage capacity information obtained in step S1 and the amount of accumulated water calculated in step S32, to obtain the friction coefficient between the tire and the road surface. The capacity of the drainage facility determines the speed at which accumulated water formed on the road surface by rainfall is discharged, which directly affects the friction coefficient between the road surface and the tire.

[0042] S331. The friction coefficient f is affected by the thickness of the water film on the road surface H. The thickness of the water film on the road surface is related to the drainage capacity of the drainage facilities. The calculation of the water film thickness is divided into three cases. Specifically, when the drainage facilities have good capacity, the rainfall Q is equal to the drainage volume Q. c ; When the drainage facilities are not capable, the rainfall Q is greater than the drainage Q c , water accumulation on the road surface V j1 (H); when there is no drainage capacity, the drainage volume is zero, and the rainfall Q is equal to the water volume V j1 (H).

[0043] Water film thickness calculation:

[0044] (1) Calculation of rainfall Q:

[0045] Q=I R LW×10 -3

[0046] Among them, Q represents the rainfall in the confluence area of ​​the tested road section, which is related to the composite slope of the road and the drainage facilities. R It represents rainfall intensity, L represents drainage length parallel to driving direction, and W represents road width.

[0047] (2) Displacement Q c Calculation: When a curb is set at the outer edge of the hard shoulder of the road, the drainage capacity of the drainage facility is calculated according to the following formula:

[0048]

[0049] Among them, Q c Indicates the displacement, i h represents the transverse slope, n represents the roughness coefficient of the asphalt pavement, H represents the water film thickness, and I represents the longitudinal slope.

[0050] (3) When the road has curbstones and the drainage facilities have good drainage capacity, the calculation of the water film thickness H is: the rainfall is equal to the drainage volume. The water film thickness is calculated according to the following formula.

[0051]

[0052] Where H represents the water film thickness, I R represents rainfall intensity, L represents drainage length parallel to the driving direction, W represents road width, i h represents the transverse slope, n represents the asphalt pavement roughness coefficient, and I represents the longitudinal slope.

[0053] (4) When there are curbstones on the road and the drainage facilities have poor drainage capacity or no drainage capacity, the rainfall is greater than the drainage volume and the rainfall that is not discharged in time forms water on the road surface.

[0054] Different road geometric features will result in different road surface water thickness (water film thickness) under the same rainfall intensity. According to the road geometric features, the road surface water model V ji (H) is divided into four categories, namely:

[0055] (i) When the transverse slope is greater than or equal to 0.3% and the longitudinal slope is -0.3% to +0.3%, the longitudinal slope of the road surface has poor drainage, and drainage is mainly carried out through the transverse slope. When the longitudinal slope section with poor drainage contains a concave vertical curve slope change point, the corresponding water volume V of the model is j1 (H) is:

[0056]

[0057] Where R is the vertical curve radius, H is the water film thickness, i h The horizontal slope.

[0058] (ii) When the transverse slope is greater than or equal to 0.3%, the longitudinal slope is -0.3% to +0.3%, and the poorly drained longitudinal slope section is located on the side of a vertical curve or on a straight slope. At this time, the corresponding water volume V j2 (H) is:

[0059]

[0060] Among them, H is the water film thickness, W is the road width, and I is the longitudinal slope.

[0061] (iii) When the transverse slope and longitudinal slope are both -0.3% to +0.3%, the road transverse slope and longitudinal slope are poorly drained. At this time, the corresponding water volume V j3 (H) is,

[0062]

[0063] Among them, R is the vertical curve radius, H is the water film thickness, and W represents the road width.

[0064] (iv) When the transverse slope is -0.3% to +0.3% and the longitudinal slope is greater than or equal to 0.3%, the corresponding water volume V j4 (H) is,

[0065]

[0066] Among them, H represents the water film thickness, L represents the drainage length parallel to the driving direction, and i h Indicates the transverse slope.

[0067] (5) When the road has curbstones and the drainage facilities have poor drainage capacity, the water film thickness H is calculated according to the following formula:

[0068] V ji (H) = Q-3600aQ c

[0069] Where V ji (H) is the volume of water accumulation, i is 1, 2, 3, 4, Q is the rainfall, a is the coefficient of drainage facility performance evolution, and is related to the timeliness of drainage facility maintenance. c For displacement.

[0070] (6) When the road has curbstones and no drainage facilities have drainage capacity, the water film thickness H is calculated according to the following formula:

[0071] V ji (H) = Q

[0072] S332: According to the water film thickness, the road friction coefficient corresponding to different water film thicknesses of the road section is calculated by the following formula:

[0073] f=a1H 3 +a2H 2 +a3H+C

[0074] Among them, f is the friction coefficient of the road surface, H is the thickness of the water film, a1, a2, a3, and C are constants, which are related to the characteristics of the road surface material, service life, and construction depth. The constant term can be manually input into the system through the friction coefficient measurement experiment of the tested highway. Since the road surface has variability with the service life, the value of the constant term needs to be regularly inspected and corrected.

[0075] like Figure 3 As shown, an embodiment of the present invention further provides a system for evaluating the friction coefficient between automobile tires and road surfaces in a rainy environment, comprising a weather information processing module, a road information processing module, a drainage facility capacity analysis module, a friction coefficient model calculation module, and an information display module;

[0076] Weather information processing module, used to process weather forecast information, user input information, and information collected by roadside meteorological equipment;

[0077] Road information processing module, used for multi-source heterogeneous information processing and obtaining road geometry features, pavement characteristics, and service life information;

[0078] Drainage facility capacity analysis module, used for image recognition, analysis, judgment and evaluation of drainage facility usage status;

[0079] The friction coefficient model calculation module is used to calculate the friction coefficient between the car tire and the road surface under the rainy environment according to the weather information, road information and drainage facility capacity information;

[0080] The information display module is used to display the friction coefficient data between the car tires and the road surface.

[0081] The friction coefficient model calculation module includes a rainfall calculation module, a drainage calculation module, a water accumulation calculation module and a friction coefficient model module. The rainfall calculation module is used to calculate the rainfall, the drainage calculation module is used to calculate the drainage, and the water accumulation calculation module is used to calculate the water accumulation under different road geometric characteristics based on the road geometric feature information combined with the rainfall and drainage; the friction coefficient model module is used to calculate the friction coefficient between the tire and the road surface under different rainfall intensities.

[0082] The friction coefficient model module contains the friction coefficient model, which is:

[0083] f=a1H 3 +a2H 2 +a3H+C

[0084] Among them, f is the road friction coefficient, H is the water film thickness, a1, a2, a3, and C are constants.

[0085] In summary, the system and method for evaluating the friction coefficient between automobile tires and road surfaces in a rainfall environment provided by the embodiments of the present invention can obtain road geometry feature information of the tested section and drainage capacity information of drainage facilities, obtain rainfall intensity information of the tested section with the help of roadside meteorological radar, and directly and quickly predict the friction coefficient between tires and road surfaces under different sections and different rainfall intensity combinations based on the rainfall intensity information, road geometry feature information and drainage capacity information of drainage facilities, which can solve the technical problems of difficulty in real-time dynamic measurement of road friction coefficient and inaccurate measurement on rainy days.

[0086] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for evaluating the friction coefficient between automobile tires and road surfaces in a rainy environment, characterized in that: The following steps are involved: S1. Obtaining road geometry information of the tested road section and drainage capacity information of drainage facilities; S2. Obtaining rainfall intensity information of the tested road section; S3, calculating the friction coefficient between the tire and the road under different road sections and different combinations of rainfall intensities according to the road geometry information and drainage capacity information obtained in step S1 and the rainfall intensity information obtained in step S2, comprising the following steps: S31, calculating rainfall and drainage according to the rainfall intensity information obtained in step S2; S32, calculating the amount of water accumulation under different road geometric characteristics based on the road geometric characteristic information obtained in step S1 and the rainfall and drainage calculated in step S31; When a curb is set at the outer edge of the hard shoulder of the road, the calculation formula for the drainage volume is as follows: Among them, Q c Indicates the displacement, i h represents the transverse slope, n represents the roughness coefficient of the asphalt pavement, H represents the water film thickness, and I represents the longitudinal slope; S33. Calculate the friction coefficient between the tire and the road surface under different rainfall intensities using a friction coefficient model based on the drainage capacity information obtained in step S1 and the amount of accumulated water calculated in step S32 to obtain the friction coefficient between the tire and the road surface.

2. The method for evaluating the friction coefficient between automobile tires and road surfaces in a rainy environment according to claim 1, characterized in that: In step S31, the calculation formula of the rainfall is as follows: Q=I R LW×10 -3 Among them, Q represents the rainfall in the confluence area of ​​the tested road section, which is related to the composite slope of the road and the drainage facilities. R It represents rainfall intensity, L represents drainage length parallel to driving direction, and W represents road width.

3. The method for evaluating the friction coefficient between automobile tires and road surfaces in a rainy environment according to claim 1, characterized in that: In step S33, the friction coefficient model is: f=a1H 3 +a2H 2 +a3H+C Among them, f is the road friction coefficient, H is the water film thickness, a1, a2, a3, and C are constants.

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