A rain day mountainous area highway curve variable speed limit early warning method and system

Abstract

The present application belongs to the field of road traffic safety technology, and particularly relates to a variable speed limit early warning method and system for a mountainous road curve in rainy weather, which is based on a tire-fluid-pavement coupling side slip anti-skid model, combines various factors such as vehicle speed, pavement polishing, water film thickness, and predicts the anti-skid performance decay characteristics of the curved pavement, and then calculates and generates the available anti-skid value of the curved pavement and the vehicle anti-skid demand value according to the analysis of the vehicle lateral slip mechanism of the curve, obtains the safe speed limit value, and forms a safe speed limit database; so that when the vehicle is driving on the mountainous road in rainy weather, the vehicle, pavement and rainy weather environment analysis parameters are collected, the safe speed limit value in the database is matched, and early warning is performed. The present application can solve the problem that the influence of the rainy weather environment and the actual texture polishing state of the pavement on the pavement anti-skid performance is not considered in the existing scheme, resulting in inaccurate variable speed limit early warning value.

Description

Technical Field

[0001] This invention belongs to the field of road traffic safety technology, and in particular relates to a method and system for predicting variable speed limits on curves in mountainous areas during rainy weather. Background Technology

[0002] my country's mountainous roads are long and have many curves. In rainy weather, vehicles are prone to skidding accidents caused by speeding when driving on curves. Therefore, reasonably limiting vehicle speed is an effective way to reduce the occurrence of curve accidents, such as implementing variable speed limit warnings for vehicles.

[0003] Current research on vehicle variable speed limit control algorithms generally includes the following aspects: First, based on the variable speed limit variation law derived from the spatial adaptive algorithm, recommended variable speed limit values ​​are proposed under different rainfall intensities and visibility conditions; second, vehicle stability models are used to calculate the critical speed value for safe driving; third, safe vehicle speeds on curves are studied from three aspects: actual surveys, sight distance models, and VISSIM simulations; fourth, vehicle dynamics analysis is used to analyze vehicle lateral slippage and loss of control; and fifth, curve curvature and road surface friction coefficients are obtained based on GPS and vehicle motion state data. However, most of the above-mentioned solutions do not consider the impact of rainy weather conditions and the actual surface texture and polishing state on the road surface's anti-skid performance, resulting in limited coverage of scenarios. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a method and system for predicting variable speed limits on mountain roads in rainy weather, so as to solve the problem that existing solutions do not take into account the impact of rainy weather conditions and the actual texture and polishing state of the road surface on the anti-skid performance of the road surface, resulting in inaccurate variable speed limit warning values.

[0005] The basic solution provided by this invention is: a method for providing variable speed limit warnings on mountain road curves in rainy weather, comprising:

[0006] S1: Acquire vehicle tire data and road surface data to construct a tire-fluid-road surface coupled lateral anti-skid model;

[0007] S2: Conduct road skid resistance simulation tests based on the road surface polishing state at different service stages, and extract low-speed skid resistance values ​​and high-speed skid resistance values ​​to generate road skid resistance degradation data;

[0008] S3: Verify the results of the anti-skid simulation test of the road surface based on the lateral anti-skid model, and construct a prediction model for the degradation of anti-skid performance of the road surface in water accumulation bends. Based on the anti-skid degradation data of the road surface, predict the degradation characteristics of the anti-skid performance of the test bend section under any vehicle and different environmental conditions.

[0009] S4: Calculate the available anti-skid value and the vehicle's anti-skid requirement value on curved road sections under different environmental conditions based on the anti-skid performance decay characteristics, and take the speed value when the available anti-skid value equals the vehicle's anti-skid requirement value as the critical safe speed to form a safe speed limit database;

[0010] S5: Intelligently identifies vehicle information and road surface anti-skid performance degradation characteristics through vehicle sensors, matches the critical safe speed in the safety speed limit database as the vehicle's safe cornering speed limit value, and pushes it to the user.

[0011] Furthermore, S1 includes:

[0012] S1-1: Establish a tire sub-model based on the vehicle tire's geometric dimensions, material properties, inflation pressure, load, slip ratio, and sideslip angle;

[0013] S1-2: Using Eulerian elements, a fluid sub-model is established based on the road surface fluid characteristics, water film thickness, and flow velocity. The interaction between the fluid and the tire is simulated using the Eulerian-Lagrange coupling algorithm.

[0014] S1-3: Construct a road sub-model based on the macroscopic and microscopic texture, permeability coefficient, and road drainage characteristics of the road surface, and numerically characterize the differences in anti-skid performance of the road sub-model based on the tire-road contact algorithm, and associate the fluid sub-model based on the boundary conditions;

[0015] S1-4: Construct a tire-fluid-road coupled lateral anti-skid model using finite element software, combining tire sub-model, fluid sub-model, and road surface sub-model.

[0016] Furthermore, S2 includes:

[0017] S2-1: Conduct outdoor skid resistance performance monitoring of the test road section at dynamic time intervals to obtain low-speed skid resistance values ​​and high-speed skid resistance values ​​at different time periods;

[0018] S2-2: Based on the low-speed and high-speed skid resistance values ​​monitored at different time periods, generate skid resistance value decay data with speed over the service life of the road section, which serves as road surface skid resistance degradation data.

[0019] Furthermore, S4 includes:

[0020] S4-1: Construct a model of a vehicle's trajectory on a curve under water accumulation conditions and obtain the maximum sideslip angle under extreme sideslip conditions.

[0021] S4-2: Calculate the vehicle's available anti-skid value according to the preset formula for calculating available anti-skid value;

[0022] S4-3: Calculate the vehicle's anti-skid requirement value according to the preset anti-skid requirement value calculation formula;

[0023] S4-4: The speed value corresponding to the available anti-skid value equal to the vehicle's anti-skid requirement value is taken as the critical safe speed, and a safe speed limit database is formed.

[0024] Furthermore, the formula for calculating the available anti-skid value is as follows:

[0025] SN a =SN(x)×sinα+SN(y)×cosα

[0026] Where SN(x) is the longitudinal anti-skid value acting on the tire plane, SN(y) is the lateral anti-skid value perpendicular to the tire plane, and α is the tire slip angle under normal driving conditions.

[0027] The formula for calculating the anti-slip requirement value is as follows:

[0028] SN d =(V 2 / gR-e)×100

[0029] Where V represents vehicle speed, R represents the radius of the curve, and e represents superelevation parameter.

[0030] A variable speed limit warning system for mountain roads in rainy weather, applied to the aforementioned variable speed limit warning method for mountain roads in rainy weather, includes a lateral skid resistance model construction module, a pavement skid resistance decay analysis module, a waterlogged pavement skid resistance decay prediction module, a variable speed limit calculation module, and a data push module, wherein:

[0031] The lateral slip resistance model building module is used to acquire vehicle tire data and road surface data to build a tire-fluid-road coupled lateral slip resistance model;

[0032] The road skid resistance degradation analysis module is used to conduct road skid resistance simulation tests based on the road polishing state at different road service stages, and extract low-speed skid resistance values ​​and high-speed skid resistance values ​​to generate road skid resistance degradation data;

[0033] The anti-skid degradation prediction module for waterlogged road surfaces is used to verify the results of anti-skid simulation tests based on the lateral anti-skid model, and to construct a prediction model for the anti-skid performance degradation of waterlogged curved road surfaces. Based on the anti-skid degradation data, it predicts the anti-skid performance degradation characteristics of the test curved road sections under any vehicle and different environmental conditions.

[0034] The variable speed limit calculation module is used to calculate the available anti-skid value and the vehicle's anti-skid requirement value on curved road sections under different environmental conditions based on the anti-skid performance decay characteristics. The speed value when the available anti-skid value equals the vehicle's anti-skid requirement value is taken as the critical safe speed, forming a safe speed limit database.

[0035] The data push module is used to intelligently identify vehicle information and road surface anti-skid performance degradation characteristics using vehicle sensors, match the critical safe speed in the safe speed limit database as the vehicle's safe cornering speed limit value, and push it to the user.

[0036] The principle and advantages of this invention are as follows: This application provides a variable speed limit warning method and system for mountain roads in rainy weather curves. Based on a tire-fluid-road surface coupling lateral anti-skid model, it can simulate and verify the anti-skid performance of the road surface by combining multiple factors such as vehicle speed, road surface polishing, and water film thickness. Simultaneously, based on a prediction model for the degradation of anti-skid performance on waterlogged curves, it can predict the anti-skid degradation characteristics of the road surface, and then calculate and generate available anti-skid values ​​and vehicle anti-skid demand values ​​to obtain safe speed limits and form a safe speed limit database. This allows vehicles to collect and analyze parameters in front of them when driving on mountain roads in rainy weather, match them with the safe speed limit values ​​in the database, and provide early warnings, enabling vehicles to safely pass through mountain curves in rainy weather, thereby reducing traffic accidents, improving traffic efficiency, and achieving efficient and safe passage. Attached Figure Description

[0037] Figure 1 This is a flowchart of an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the lateral slip resistance model according to an embodiment of the present invention;

[0039] Figure 3 This is a simulation of the fluid-structure interaction control mechanism for lateral anti-slip in an embodiment of the present invention;

[0040] Figure 4 This is a road surface skid resistance degradation curve diagram according to an embodiment of the present invention;

[0041] Figure 5 This is a schematic diagram of the anti-skid state curve of a flooded road surface according to an embodiment of the present invention;

[0042] Figure 6 This is a vehicle sideslip analysis anti-skid curve diagram according to an embodiment of the present invention;

[0043] Figure 7 This is a schematic diagram illustrating the analysis of the vehicle's trajectory and the lateral slip force of the tires on a curve, according to an embodiment of the present invention.

[0044] Figure 8 This is a functional block diagram of an embodiment of the present invention. Detailed Implementation

[0045] The following detailed description illustrates the specific implementation method:

[0046] The basic implementation examples are as follows: Figure 1 As shown: A method for providing variable speed limit warnings on mountain road curves in rainy weather, comprising:

[0047] S1: Acquire vehicle tire data and road surface data to construct a tire-fluid-road coupled lateral anti-skid model; wherein, S1 includes:

[0048] S1-1: Establish a tire sub-model based on the vehicle tire's geometric dimensions, material properties, inflation pressure, load, slip ratio, and sideslip angle;

[0049] S1-2: Using Eulerian elements, a fluid sub-model is established based on the road surface fluid characteristics, water film thickness, and flow velocity. The interaction between the fluid and the tire is simulated using the Eulerian-Lagrange coupling algorithm.

[0050] S1-3: Construct a road sub-model based on the macroscopic and microscopic texture, permeability coefficient, and road drainage characteristics of the road surface, and numerically characterize the differences in anti-skid performance of the road sub-model based on the tire-road contact algorithm, and associate the fluid sub-model based on the boundary conditions;

[0051] S1-4: Construct a tire-fluid-road coupled lateral anti-skid model using finite element software, combining tire sub-model, fluid sub-model, and road surface sub-model.

[0052] Specifically, such as Figure 2 This is a schematic diagram of the lateral slip resistance model according to an embodiment of the present invention. Figure 3 The diagram illustrates the fluid-structure interaction control mechanism of the lateral anti-skid model. During the ABAQUS modeling process, a tire model is constructed based on the tire's structural characteristics, and material input parameters are selected according to the tire's material properties. The rubber portion of the pneumatic tire is simulated using Lagrangian elements, while the cords within the cord and belt layers are simulated using embedded Rebar elements. Eulerian elements are used to simulate fluid deformation, allowing water to flow arbitrarily within Eulerian units. To improve the computational efficiency of the anti-skid model, different types of actual road surfaces are simulated as rigid bodies. The differences in anti-skid performance caused by road surface materials and textures are numerically characterized using a tire-road contact algorithm. After the tire sub-model is constructed, it interacts with the fluid sub-model using an Eulerian-Lagrange coupling algorithm, outputting parameters such as tire deformation, free surface of water flow, hydrodynamic pressure, fluid lift force, and fluid resistance. Simultaneously, the tire sub-model interacts with the road surface sub-model via a contact algorithm, outputting tire footprint shape and area, tread friction, ground contact pressure, normal contact force, and shear contact force. The road surface sub-model interacts with the fluid sub-model through boundary conditions, outputting parameters such as water flow-road surface contact area and road drainage. Therefore, the lateral slip resistance model constructed in this application can consider the influence of various factors such as vehicle speed, road surface texture polishing, and water film thickness on the anti-skid performance of curved road surfaces, and has a good predictive effect on the variable speed limit value of vehicles driving on mountain curves in rainy weather.

[0053] S2: Conduct pavement skid resistance simulation tests based on the pavement polishing state at different service stages, and extract low-speed and high-speed skid resistance values ​​to generate pavement skid resistance degradation data; wherein, S2 includes:

[0054] S2-1: Conduct outdoor skid resistance performance monitoring of the test road section at dynamic time intervals to obtain low-speed skid resistance values ​​and high-speed skid resistance values ​​at different time periods;

[0055] S2-2: Based on the low-speed and high-speed skid resistance values ​​monitored at different time periods, generate skid resistance value decay data with speed over the service life of the road section, which serves as road surface skid resistance degradation data.

[0056] In this application, to better characterize the degradation law of pavement skid resistance with time and speed, such as Figure 4 As shown, the low-speed skid resistance values ​​SN0 and high-speed skid resistance values ​​SN0 under different road surface service stages are used. 64 Together, they represent the road surface skid resistance degradation characteristics. SN0 characterizes the low-speed skid resistance value caused by road surface microtexture, and its value is related to the pendulum value BPN; SN 64 The high-speed skid resistance value of pavement, influenced by macroscopic texture, is measured using an ASTM skid trailer. This application primarily uses the lateral force coefficient (SFC) to characterize the high-speed skid resistance value in curves. This application conducts indoor accelerated loading experiments on the test pavement aggregates to obtain the pendulum bearing capacity (BPN) under different polishing conditions. Outdoor skid resistance performance is observed on the test road sections at dynamic intervals, measuring BPN and SFC at different time points. Through effective monitoring, the attenuation curve of skid resistance value with speed over the entire pavement service life is obtained.

[0057] S3: The results of the pavement anti-skid simulation test were verified based on the lateral anti-skid model, and a prediction model for the degradation of anti-skid performance of a water-filled bend road surface was constructed. Based on the pavement anti-skid degradation data, the degradation characteristics of anti-skid performance of the test bend road section under any vehicle and different environmental conditions were predicted. The pavement anti-skid state theory states that at a given time point, each unit length of pavement has a fixed anti-skid value under a given set of pavement, environmental, and vehicle operating conditions. Based on this conclusion, the tire-water-pavement three-body dynamic coupling lateral anti-skid model based on solid mechanics and fluid dynamics can fully represent the anti-skid characteristics of the pavement under different operating conditions. By verifying the anti-skid test results of a certain road section using the established lateral anti-skid model and determining its friction input parameters, the anti-skid performance of the pavement under any vehicle and environmental conditions can be simulated, providing a reference for the evolution of anti-skid performance for current pavement friction management and safe speed determination. Figure 5 As shown, the anti-skid state curves represent the anti-skid degradation curves of the road surface at different speeds and road surface water film thicknesses.

[0058] S4: Calculate the available anti-skid value and the vehicle's anti-skid requirement value on curved road sections under different environmental conditions based on the anti-skid performance degradation characteristics, and use the speed at which the available anti-skid value equals the vehicle's anti-skid requirement value as the critical safe speed, forming a safe speed limit database; S4 includes:

[0059] S4-1: Construct a model of a vehicle's trajectory on a curve under water accumulation conditions and obtain the maximum sideslip angle under extreme sideslip conditions.

[0060] S4-2: Calculate the vehicle's available anti-skid value according to the preset formula for calculating available anti-skid value;

[0061] S4-3: Calculate the vehicle's anti-skid requirement value according to the preset anti-skid requirement value calculation formula;

[0062] S4-4: The speed value corresponding to the available anti-skid value equal to the vehicle's anti-skid requirement value is taken as the critical safe speed, and a safe speed limit database is formed.

[0063] In this embodiment, the available anti-skid value and the vehicle's anti-skid requirement value are determined for a vehicle laterally skidding across the road surface. The available anti-skid value is the maximum anti-skid value that the curved road surface can provide in the lateral skid direction under various working conditions. The vehicle's anti-skid requirement value is the lateral anti-skid value required for a vehicle to resist centrifugal force when passing through a curve at a certain speed. The relationship between the available anti-skid curve and the anti-skid requirement curve is shown in [reference needed]. Figure 6 Among them, the available anti-skid value is represented by SN. a The vehicle's anti-skid requirement value is expressed in SN. d It means that when SN a <SN d At that time, the vehicle will slip laterally, SN a >SN d At that time, the vehicle maintains safe driving without skidding, when SN a =SN d At this point, the speed at the intersection of the two anti-skid curves is the critical safe speed. The safety margin for curve speed is defined as the difference between the maximum safe driving speed and the design speed, i.e.: ΔV = V max -V d The anti-skid safety margin is defined as the difference between the available anti-skid value and the required anti-skid value at the design speed, i.e.: ΔSN = SN a -SN dBoth the speed safety margin ΔV and the anti-skid safety margin ΔSN can be used to assess the risk of vehicle sideslip in curves. When the speed safety margin ΔV < 0 or the anti-skid safety margin ΔSN < 0, it indicates that the vehicle has experienced sideslip in the curve; ΔV > 0 or ΔSN > 0, ensuring vehicle safety in curves. The smaller the values ​​of the speed safety margin ΔV and the anti-skid safety margin ΔSN, the higher the risk of vehicle sideslip. The anti-skid safety margin ΔSN is used to measure the degree of improvement in the anti-skid performance of the road surface, providing a basis for judging sideslip in engineering applications.

[0064] Therefore, for the available anti-skid value SN a And vehicle anti-skid requirement value SN d Solving this problem is particularly important, specifically, for example... Figure 7 The diagram shows the vehicle's trajectory on a curve. When the vehicle turns, the velocity direction does not coincide with the tire plane direction, resulting in a certain sideslip angle α. Under extreme sideslip conditions, the tire sideslip direction is parallel to the centrifugal force direction. The angle between the sideslip velocity direction and the tire plane at this extreme sideslip angle is defined as the maximum sideslip angle, with a value of 90°-α. The tire-road anti-skid value SN under this maximum sideslip angle of 90°-α is defined as the usable anti-skid value for sideslip analysis. a Based on the longitudinal anti-skid value SN(x) and lateral anti-skid value SN(y) of the tire, the usable anti-skid value SN in the vehicle's sideslip direction is calculated. a :

[0065] SN a =SN(x)×sinα+SN(y)×cosα

[0066] Where SN(x) is the longitudinal anti-skid value acting on the tire plane, SN(y) is the lateral anti-skid value perpendicular to the tire plane, and α is the tire slip angle under normal driving conditions.

[0067] Anti-slip demand value SN d The tire-road anti-skid performance required for a car to resist centrifugal force while driving normally on a circular curve is related to vehicle speed V, the radius of the circular curve R, and superelevation e. Based on the force analysis of a car in a curve, its calculation formula can be obtained as follows:

[0068] SN d =(V 2 / gR-e)×100

[0069] Where V represents vehicle speed, R represents the radius of the curve, and e represents superelevation parameter.

[0070] The advantages and positive effects of this algorithm are mainly reflected in its use of finite element simulation technology to construct a coupled tire-water flow-road surface anti-skid model to calculate accurate safe speed limits for mountain curves in rainy weather. This algorithm comprehensively considers the anti-skid decay characteristics and water film thickness changes throughout the entire life cycle of the curved road surface. Combined with the relationship between the anti-skid performance of curved roads in rainy weather and various factors such as road surface water film thickness, tire type, speed, and slip ratio, it provides a more comprehensive digital foundation for the dynamic speed limit control of vehicles, establishing a more complete intelligent variable speed limit system. This provides important theoretical basis and reference for research and development in related fields, promoting technological progress in this area.

[0071] S5: Intelligently identifies vehicle information and road surface anti-skid performance degradation characteristics through vehicle sensors, matches the critical safe speed in the safety speed limit database as the vehicle's safe cornering speed limit value, and pushes it to the user.

[0072] like Figure 8 As shown, in another embodiment of this example, a variable speed limit warning system for mountain roads in rainy weather is also included, applied to the aforementioned variable speed limit warning method for mountain roads in rainy weather. This system includes a lateral skid resistance model construction module, a road surface skid resistance degradation analysis module, a waterlogged road surface skid resistance degradation prediction module, a variable speed limit calculation module, and a data push module, wherein:

[0073] The lateral slip resistance model building module is used to acquire vehicle tire data and road surface data to build a tire-fluid-road coupled lateral slip resistance model;

[0074] The road skid resistance degradation analysis module is used to conduct road skid resistance simulation tests based on the road polishing state at different road service stages, and extract low-speed skid resistance values ​​and high-speed skid resistance values ​​to generate road skid resistance degradation data;

[0075] The anti-skid degradation prediction module for waterlogged road surfaces is used to verify the results of anti-skid simulation tests based on the lateral anti-skid model, and to construct a prediction model for the anti-skid performance degradation of waterlogged curved road surfaces. Based on the anti-skid degradation data, it predicts the anti-skid performance degradation characteristics of the test curved road sections under any vehicle and different environmental conditions.

[0076] The variable speed limit calculation module is used to calculate the available anti-skid value and the vehicle's anti-skid requirement value on curved road sections under different environmental conditions based on the anti-skid performance decay characteristics. The speed value when the available anti-skid value equals the vehicle's anti-skid requirement value is taken as the critical safe speed, forming a safe speed limit database.

[0077] The data push module is used to intelligently identify vehicle information and road surface anti-skid performance degradation characteristics using vehicle sensors, match the critical safe speed in the safe speed limit database as the vehicle's safe cornering speed limit value, and push it to the user.

[0078] The above are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for providing variable speed limit warnings on curves in mountainous areas during rainy weather, characterized in that: include: S1: Acquire vehicle tire data and road surface data to construct a tire-fluid-road coupled lateral anti-skid model; S2: Conduct road skid resistance simulation tests based on the road surface polishing state at different service stages, and extract low-speed skid resistance values ​​and high-speed skid resistance values ​​to generate road skid resistance degradation data; S3: Verify the results of the anti-skid simulation test of the road surface based on the lateral anti-skid model, and construct a prediction model for the degradation of anti-skid performance of the road surface in water accumulation bends. Based on the anti-skid degradation data of the road surface, predict the degradation characteristics of the anti-skid performance of the test bend section under any vehicle and different environmental conditions. S4: Calculate the available anti-skid value and the vehicle's anti-skid requirement value on curved road sections under different environmental conditions based on the anti-skid performance decay characteristics, and take the speed value when the available anti-skid value equals the vehicle's anti-skid requirement value as the critical safe speed to form a safe speed limit database; S5: Intelligently identifies vehicle information and road surface anti-skid performance degradation characteristics through vehicle sensors, matches the critical safe speed in the safety speed limit database as the vehicle's safe cornering speed limit value, and pushes it to the user. S1 includes: S1-1: Establish a tire sub-model based on the vehicle tire's geometric dimensions, material properties, inflation pressure, load, slip ratio, and sideslip angle; S1-2: Using Eulerian elements, a fluid sub-model is established based on the road surface fluid characteristics, water film thickness, and flow velocity. The interaction between the fluid and the tire is simulated using the Eulerian-Lagrange coupling algorithm. S1-3: Construct a road sub-model based on the macroscopic and microscopic texture, permeability coefficient, and road drainage characteristics of the road surface, and numerically characterize the differences in anti-skid performance of the road sub-model based on the tire-road contact algorithm, and associate the fluid sub-model based on the boundary conditions; S1-4: Construct a tire-fluid-road coupled lateral anti-skid model using finite element software, combining tire sub-model, fluid sub-model, and road surface sub-model.

2. The method for variable speed limit warning on mountain road curves in rainy weather according to claim 1, characterized in that: S2 includes: S2-1: Conduct outdoor skid resistance performance monitoring of the test road section at dynamic time intervals to obtain low-speed skid resistance values ​​and high-speed skid resistance values ​​at different time periods; S2-2: Based on the low-speed and high-speed skid resistance values ​​monitored at different time periods, generate skid resistance value decay data with speed over the service life of the road section, which serves as road surface skid resistance degradation data.

3. The method for variable speed limit warning on mountain road curves in rainy weather according to claim 2, characterized in that: S4 includes: S4-1: Construct a model of a vehicle's trajectory on a curve under water accumulation conditions and obtain the maximum sideslip angle under extreme sideslip conditions. S4-2: Calculate the vehicle's available anti-skid value according to the preset formula for calculating available anti-skid value; S4-3: Calculate the vehicle's anti-skid requirement value according to the preset anti-skid requirement value calculation formula; S4-4: The speed value corresponding to the available anti-skid value equal to the vehicle's anti-skid requirement value is taken as the critical safe speed, and a safe speed limit database is formed.

4. The method for variable speed limit warning on mountain road curves in rainy weather according to claim 3, characterized in that: The formula for calculating the available anti-skid value is as follows: in, This refers to the longitudinal anti-skid value acting in the planar direction of the tire. The lateral anti-skid value is the value perpendicular to the tire plane. This refers to the tire slip angle under normal driving conditions. The formula for calculating the anti-slip requirement value is as follows: Where V represents vehicle speed, R represents the radius of the curve, and e represents superelevation parameter.

5. A variable speed limit warning system for mountain roads in rainy weather, applied to the variable speed limit warning method for mountain roads in rainy weather as described in any one of claims 1-4, characterized in that: It includes a lateral skid resistance model construction module, a pavement skid resistance decay analysis module, a waterlogged pavement skid resistance decay prediction module, a variable speed limit calculation module, and a data push module, among which: The lateral slip resistance model building module is used to acquire vehicle tire data and road surface data to build a tire-fluid-road coupled lateral slip resistance model; The road skid resistance degradation analysis module is used to conduct road skid resistance simulation tests based on the road polishing state at different road service stages, and extract low-speed skid resistance values ​​and high-speed skid resistance values ​​to generate road skid resistance degradation data; The anti-skid degradation prediction module for waterlogged road surfaces is used to verify the results of anti-skid simulation tests based on the lateral anti-skid model, and to construct a prediction model for the anti-skid performance degradation of waterlogged curved road surfaces. Based on the anti-skid degradation data, it predicts the anti-skid performance degradation characteristics of the test curved road sections under any vehicle and different environmental conditions. The variable speed limit calculation module is used to calculate the available anti-skid value and the vehicle's anti-skid requirement value on curved road sections under different environmental conditions based on the anti-skid performance decay characteristics. The speed value when the available anti-skid value equals the vehicle's anti-skid requirement value is taken as the critical safe speed, forming a safe speed limit database. The data push module is used to intelligently identify vehicle information and road surface anti-skid performance degradation characteristics using vehicle sensors, match the critical safe speed in the safe speed limit database as the vehicle's safe cornering speed limit value, and push it to the user.

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