A method, system, storage medium and software product for evaluating dry road grip of a passenger car tire

Abstract

The present application relates to the technical field of tire performance evaluation, and particularly relates to a passenger car tire dry road grip evaluation method, system, storage medium and software product. The method is applied to dry high-asphalt road surface, and a candidate tire is tested at a speed of 100 km / h to 0 ABS braking distance under a specified air pressure and load. A "reference tire-candidate tire-reference tire" clamping cycle is used to obtain the road / environment drift amount, the candidate data is drift corrected by time interpolation, and a normalized dry road grip index is calculated and output. The method can significantly reduce the test dispersion caused by time-varying factors, and improve the comparability and discrimination sensitivity of cross-period, cross-site and cross-batch results.

Description

Technical Field

[0001] This invention relates to the field of tire performance evaluation technology, and in particular to a method, system, storage medium, and software product for evaluating the dry road grip capability of passenger car tires. Background Technology

[0002] As the only mechanical connection between a vehicle and the road surface, the tire's longitudinal grip capability directly determines the vehicle's handling stability and safety boundaries under typical conditions such as acceleration, emergency braking, and high-speed lane changes. In passenger car usage scenarios, the vast majority of a vehicle's mileage occurs on dry roads. On such roads, tire grip capability primarily depends on the interaction mechanism between the tread rubber and the road surface's micro-texture, including but not limited to: rubber adhesion effect, energy dissipation dominated by hysteresis loss, and changes in effective contact area caused by the coupling of ground pressure distribution and tread block stiffness. Compared to wet road grip performance, dry roads do not present significant water film drainage / hydroplaning issues. The evaluation focus shifts from water film breaking capability to the force-energy conversion efficiency under the coupling of tread material and road surface texture. The influencing factors, test sensitivity, and data dispersion sources are all significantly different. Therefore, conclusions based solely on wet road grip tests cannot be extrapolated to the true performance of ultimate braking capabilities on dry roads.

[0003] In current engineering practice, the braking distance from a given initial speed to a complete stop is one of the most intuitive and easily understood indicators of longitudinal grip on dry roads by OEMs and consumers. Internationally, several test recommendations and standard methods have been developed for braking distance measurement, intended for publication by OEMs or the media. For example, the document (SAE J2909™ JUN2018 "Light Vehicle Dry & Wet Stopping Distance Test Procedure") proposes recommended practices for measuring vehicle straight-line braking distances on dry or wet asphalt roads. The goal is to generate braking distance data that can be published by manufacturers or the media, and to provide general guidance on test preparation, test paths, speed selection, etc. This type of methodology emphasizes consistency in the testing process, helping to reduce operational differences caused by different testers or different testing sessions. However, its primary focus is on publishing vehicle braking distances, rather than specifically addressing the standardized needs for evaluating tire grip on dry roads.

[0004] For example, the document (ISO 21994:2022 "Passenger cars—Stopping distance atstraight-line braking with ABS—Open-loop test method") provides an open-loop test method for determining the straight-line braking distance of a vehicle under full ABS intervention conditions, emphasizing that this method serves as a reference to ensure high repeatability and comparability. This standard is of reference value for the basic boundary conditions and consistency control of the test procedure, but its evaluation object still focuses on the stopping distance of the vehicle under ABS braking conditions, leaning more towards measuring the overall matching effect of the vehicle's braking system and tires. When it is directly used for comparative evaluation between different tires, it may still be affected by factors such as road surface drift, environmental changes, vehicle brake system thermal fade, and differences in tire thermal state, resulting in incomparable braking distances measured for the same tire at different sites / on different dates, and difficulties in aligning results between different manufacturers / testing institutions.

[0005] Chinese patent document (CN112557065B) proposes to combine bench verification with vehicle verification to conduct multi-dimensional verification of straight-line braking, steering braking, etc., and mentions straight-line braking test with 100km / h as the starting braking speed. This type of solution emphasizes a multi-dimensional verification and bench-vehicle consistency verification process framework, focusing on the construction of the verification system and the analysis of the impact of parameter dimensions on braking performance. However, from the perspective of forming an industry-wide universal evaluation method for passenger car tire dry road grip capability, there are still some shortcomings: First, the unified test boundary conditions required for dry road grip evaluation often need further structured constraints; otherwise, different institutions may still have a large degree of freedom in specific implementation. Second, braking distance data is highly sensitive to road surface micro-state and environmental disturbances. Especially in different time periods or different test batches on the same day, road surface temperature, dust pollution, tire temperature rise, and braking system status can all introduce slow drift systematic errors. Without an operable drift identification and suppression mechanism, simply increasing the number of repetitions cannot fundamentally solve the problem of cross-test comparability. Third, in the tire grip capability evaluation scenario, companies often want to obtain evaluation results that can be benchmarked horizontally. If only the original braking distance is output, it may still be difficult to establish a unified standard due to differences in vehicle platform, braking system, test site, and execution procedures.

[0006] In addition, the implementation of dry road surface grab evaluation faces several objective difficulties: (1) Inconsistent test conditions: Different companies may use different vehicle platforms, different braking trigger strategies, different approach speed stabilization strategies and different tire pretreatment methods, resulting in increased dispersion of test results for the same tire in different institutions; (2) Time-varying nature of environment and road surface conditions: Even in the same test site, road surface temperature, cleanliness and micro-adhesion level will change over time, forming a slow drift, making it difficult to guarantee cross-time period comparability by simply taking the average of multiple repetitions; (3) Coupling of tire thermal state and braking system thermal state: Tire temperature rise will change the viscoelastic properties and contact behavior of rubber, and braking system thermal fade will change the braking force output characteristics. The superposition of the two will affect the ABS working range and braking distance; (4) Lack of unified evaluation index: In the absence of a unified evaluation framework, although braking distance is intuitive, it often lacks a normalized basis that can be directly aligned under cross-vehicle platform and cross-site conditions, making it difficult to meet the horizontal comparison needs at the industry level.

[0007] In summary, while existing technologies include recommended practices and standard methods for straight-line braking distance measurement, as well as patented solutions for braking performance verification, the evaluation of dry road grip capability for passenger car tires—an application more geared towards tire R&D and inter-company benchmarking—still suffers from several problems. These include inconsistent testing conditions and procedures, data incomparability due to environmental and road condition drift, and a lack of a unified evaluation output format for easy horizontal comparison. Therefore, there is an urgent need for a dry road grip capability evaluation method for passenger car tires that is stable and reproducible in engineering and supports cross-site / cross-batch comparisons to improve the consistency, comparability, and engineering applicability of test results. Summary of the Invention

[0008] The technical objective of this invention is to provide a method for evaluating the dry road grip capability of passenger car tires. By implementing standardized braking tests under specified dry, high-adhesion asphalt road surface and vehicle / tire boundary conditions, and introducing a test cycle with reference tire front and rear clamping and a drift correction mechanism, normalized dry road grip evaluation results are obtained. This solves the problems of inconsistent dry road braking test conditions, large data dispersion due to time-varying environmental and road conditions, and difficulty in comparing data across sites / batches in existing systems. It provides a unified, repeatable, and comparable evaluation basis for tire R&D and selection and inter-company benchmarking.

[0009] Firstly, in order to achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0010] A method for evaluating the dry road grip capability of passenger car tires, the method comprising the following steps:

[0011] S1, Test Object and Vehicle Status Setting: Install the candidate tire on at least one axle of the test vehicle, and set the tire test pressure and vehicle test load so that the tire test load accounts for 60% to 90% of the tire's rated load capacity, and the load difference between the two tires on the same axle does not exceed 10%;

[0012] S2, Instrument and Channel Calibration: Set up the braking distance test equipment and complete the communication and data acquisition channel calibration. The data acquisition channel should include at least vehicle speed, vehicle travel distance and braking trigger signal.

[0013] S3, Tire and Braking System Pre-treatment: Before the formal data collection, drive the vehicle at 60km / h for 10 minutes to warm up the candidate tires, and perform at least 2 emergency braking operations at 100km / h to complete the tire-rim-braking system break-in pre-treatment.

[0014] S4, Braking Test Cycle and Data Acquisition: A braking test cycle is conducted on a dry, flat, and clean asphalt road surface with a slope of no more than 2% in any direction. The road surface adhesion coefficient... The minimum wind speed is 0.7, and the ambient wind speed is no greater than 5 m / s; the braking test cycle includes: completing one reference braking test with the reference tire set to obtain the reference braking distance. Subsequently, candidate braking distances were obtained by completing at least three candidate braking tests with the candidate tire group. Finally, a reference braking test was conducted using the same set of reference tires to obtain the reference braking distance. In each braking test, the vehicle was brought into a stable speed range and the speed was stabilized at 105 km / h before the drive torque was cut off and the ABS was triggered until the vehicle stopped. The braking distance was calculated as the distance between the vehicle speed and the speed of the vehicle dropping from 100 km / h to 0 km / h.

[0015] S5, Drift Correction and Grip Index Calculation: Braking distance for each candidate braking test. Linear drift correction is performed based on the two reference braking distances from the reference tire set before and after, resulting in the corrected candidate braking distance. :

[0016] ;

[0017] After discarding the first data from the candidate braking test, the remaining at least three Take the arithmetic mean Further calculation of the dry road grip index ,

[0018] ;

[0019] and with This serves as an evaluation result of the candidate tires' dry road grip capability.

[0020] Preferably, in step S1, the tire test load is achieved by setting a counterweight on the test vehicle, and the counterweight includes the driver's weight and / or the passenger's weight; and the load difference between the two tires on the same axle is characterized by the ratio of the difference in the vertical load of the two tires to their average vertical load.

[0021] And / or, in step S1, the test pressure of the standard tire is 250 kPa, and the test pressure of the reinforced tire is 290 kPa.

[0022] Preferably, in step S2, the braking trigger signal includes a brake pedal switch signal and / or a brake pedal force signal, and the sampling frequency is not less than 200Hz.

[0023] Preferably, in step S3, the at least two emergency braking actions trigger the ABS within the braking range where the vehicle speed drops from 100 km / h to 0 km / h and continue until the vehicle stops.

[0024] Preferably, in step S4, the cutting off of the drive torque is achieved by at least one of the following methods: shifting into neutral; or setting the energy recovery braking torque to 0 and the drive motor torque command to 0 in electric drive / hybrid operation.

[0025] And / or, in step S4, the braking starting position of each braking test satisfies the requirement that the lateral deviation does not exceed 0.3m and the longitudinal deviation does not exceed 2.0m, so as to limit the braking to occur in the same braking area.

[0026] Preferably, in step S5, during the calculation... First, test the candidate braking system. Perform consistency screening to ensure that participants in the average... The range does not exceed 0.5m; wherein, the range is the The difference between the maximum and minimum values;

[0027] And / or, in step S5, according to The dry road grip capabilities of candidate tires are classified, and the classification thresholds include at least: when When determining that the candidate tire is not inferior to the reference tire, The candidate tire is determined to be inferior to the reference tire.

[0028] Secondly, the present invention also provides a dry road grip evaluation system for passenger car tires, used to execute the method described, comprising: a tire assembly and operating condition setting module, a data acquisition module, a braking test cycle control module, a drift correction module, and a grip index calculation module; wherein the drift correction module is used to calculate the grip index based on... , and calculate The index calculation module is used to calculate the index based on... and calculate .

[0029] Preferably, the data acquisition module includes a GPS speed and distance measurement unit and a brake trigger acquisition unit, wherein the brake trigger acquisition unit includes a brake pedal switch and / or a brake pedal force sensor;

[0030] And / or, the braking test cycle control module includes a speed stabilization control unit for prompting or constraining the vehicle speed to stabilize at 105 km / h, and a torque cut-off control unit for cutting off the drive torque before braking.

[0031] Thirdly, the present invention also provides a computer-readable storage medium having a computer program or instructions stored thereon, which, when executed by a processor, implement the steps of the method.

[0032] Fourthly, the present invention also provides a computer program product, including a computer program or instructions that, when executed by a processor, implement the steps of the method.

[0033] This invention structures and constrains the key boundary conditions of dry road braking distance testing, and employs a front-and-back clamping test cycle of reference tire-candidate tire-reference tire to explicitly quantify systematic errors caused by changes in road surface temperature, fluctuations in road surface cleanliness, and thermal drift of the tire / braking system within the same test batch. Furthermore, based on the braking results of the reference tire in two separate tests, drift correction is applied to the braking distances of the candidate tires, and a normalized dry road grip index is output. This transforms the evaluation result from the raw braking distance, which is heavily influenced by location and time, into a relative grip capability index that can be aligned across time periods and locations. Therefore, this invention can significantly reduce the dispersion of repeated tests of the same tire at different time periods, improving the reproducibility and statistical stability of multi-batch data. Simultaneously, it effectively suppresses the incomparability caused by differences in weather and road surface micro-conditions between different testing institutions on test days, thus establishing a unified benchmark for inter-company benchmarking, formula iteration screening, mass production consistency sampling, and competitor evaluation. Compared to conventional methods that rely solely on averaging multiple repetitions, this invention improves evaluation accuracy and discrimination sensitivity without increasing testing costs excessively. It can more reliably distinguish tire schemes with small differences in grip performance on dry roads, reduce misjudgments and rework caused by accidental fluctuations, accelerate R&D decisions, and enhance the credibility of road safety performance assessments. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the road surface for testing braking distance on dry roads.

[0035] Figure 2 The reference braking distance is calculated for the reference tire during two reference, candidate, and reference clamping cycles on the same test day. Over time The changing drift curve is used to characterize the time-varying drift of the road surface and environmental conditions.

[0036] Figure 3 The original braking distances of the same candidate tire scheme A in the morning and afternoon cycles. Over time A changing curve.

[0037] Figure 4 The dry road grip index for Scheme A is obtained by referencing tire clamping and performing drift correction based on time interpolation during the morning and afternoon cycles. The contrast curves.

[0038] Figure 5 To compare the dry grip index of Scheme A and Scheme B under the same reference tire standard. Comparison curves showing how the effective test sequence changes. Detailed Implementation

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0040] I. Terminology Explanation

[0041] For ease of understanding and implementation, the following terms are defined in this invention:

[0042] 1. Candidate tires: refers to tire samples whose dry road grip capability is to be evaluated. These can be products of the same specification but different formulations, different tread patterns, or different batches.

[0043] 2. Reference tire group: refers to a group of tires used as a reference standard within the same test cycle (usually a fixed tire group with the same specifications, wear conditions, and inflation conditions) to characterize the changing trend of road surface and environmental conditions over time on the test day.

[0044] 3. Test load: refers to the vertical load applied to the tire during the test, usually expressed as a proportion of the tire's rated load capacity; in this invention, this proportion is limited to... .

[0045] 4. Test pressure: refers to the inflation pressure of the tire before the test and maintained during the test; in this invention, the standard tire is... Reinforced tires .

[0046] 5. Braking distance: refers to the distance a vehicle can travel from a specified initial speed range (e.g., under specified braking conditions) to a specified braking distance. ) down to The displacement distance of the vehicle's center of gravity along the direction of travel.

[0047] 6. Braking test cycle: refers to the clamping test sequence of reference tire - candidate tire - reference tire, used to obtain front and rear reference braking results in the same cycle and to perform drift compensation on the candidate results accordingly.

[0048] 7. Drift correction: This refers to the compensation of the braking distance of the candidate tire measured at each moment by interpolation using the braking results of the reference tire group before and after two braking tests, in order to reduce the systematic deviation caused by changes in environmental and road conditions over time.

[0049] 8. Dry road grip index: This is a dimensionless evaluation quantity obtained by normalizing the braking distance of the candidate tire after drift correction relative to the reference tire benchmark. It is used for cross-site / cross-time comparison.

[0050] 9. Valid data: refers to candidate tire braking distance data that meet the requirements of the test procedure, triggering conditions, and consistency screening; in this invention, the following are typically used: discard the first time, at least 3 valid data, and the range does not exceed [a certain value]. The rules.

[0051] 10. Coefficient of adhesion (denoted as...) ): refers to the characterization parameter of the available friction level provided by the test road surface to the tire, which can be constrained and accepted through site marking, friction testing equipment or reference tire benchmark results.

[0052] II. System Structure of this Application

[0053] like Figure 1 As shown, the passenger car tire dry road grip evaluation system of the present invention can be composed of two parts: a hardware testing platform and a software computing platform. The whole system is used to execute the steps S1 to S5 as described in the claims and output the dry road grip index and related intermediate quantities.

[0054] 2.1 Hardware Test Platform

[0055] The hardware testing platform should include at least:

[0056] (1) Test vehicle module

[0057] The test vehicle is preferably a sedan or equivalent passenger vehicle equipped with ABS, and the vehicle should be in good technical condition. To reduce the impact of differences in vehicle platforms, it is recommended to use the same test vehicle to complete the comparative tests of all candidate tires within the same project. The vehicle should meet the following requirements: no obvious abnormal heat fade in the braking system, normal operation of the wheel speed sensors, and stable ABS activation; the drive system should be able to cut off the drive torque before braking by shifting to neutral or using control strategies.

[0058] (2) Tire-Rim Assembly Module

[0059] This includes candidate tire-rim assemblies and reference tire groups-rim assemblies. To ensure fairness in the comparison, it is recommended that the reference tire group and candidate tires use rims of the same specifications and be installed and dynamically balanced in the same manner. Rim specifications, tire specifications, tire wear condition (tread depth), tire temperature, etc., can all be recorded in the test log.

[0060] (3) Load and counterweight module

[0061] This system is used to achieve consistency control between test load and coaxial load. It can employ: in-vehicle counterweights (such as sandbags), adjustable counterweight frames, or vehicle load adjustment devices. The system should have weighing / axle load measurement capabilities, such as a four-wheel scale or axle load scale, to measure the vertical load on each wheel, ensuring that the load difference between the two tires on the same axle does not exceed [a certain value]. .

[0062] (4) Inflation and air pressure monitoring module

[0063] This includes inflation equipment, pressure gauges / pressure sensors, and necessary temperature and pressure compensation recording methods. Before the test, the tire pressure should be adjusted to the target test pressure and checked before and after each braking sequence; if the tire pressure deviates from the target value by more than a preset threshold (e.g., ...), ... If so, it should be readjusted and recorded.

[0064] (5) Environmental and road surface condition monitoring module

[0065] Equipment used to record and verify test boundary conditions includes: anemometers, thermometers, hygrometers, pavement thermometers (infrared or contact type), slope measuring tools (or slope calibration data provided on-site), and devices or procedures for assessing adhesion levels. System requirements must meet: slope not greater than [value missing]. Wind speed not greater than , (For specific acceptance methods, please refer to the implementation method described below).

[0066] (6) Data acquisition and measurement module

[0067] Used to collect vehicle speed, distance, and braking trigger signals. A high-frequency GPS speed and distance measurement device (such as a PBOX / VBOX or equivalent device) is preferred, simultaneously collecting:

[0068] Speed (It is recommended that the sampling frequency be no less than) Better for );

[0069] Driving distance Or displacement increment;

[0070] Braking trigger signal (This signal can be provided by the pedal switch / pedal force sensor / ABS trigger signal; a sampling frequency of at least [value missing] is recommended.) If necessary, IMU acceleration signals can be superimposed to assist in identifying the start and end times of braking and abnormal events.

[0071] 2.2 Software Computing Platform

[0072] like Figure 2 As shown, the software computing platform can be composed of the following functional modules:

[0073] Test configuration and log module: Records tire information, vehicle information, air pressure, load, environmental parameters, test site and road surface information.

[0074] Data synchronization and cleaning module: completes multi-channel data time synchronization, missing point imputation, and outlier marking.

[0075] Braking segment recognition module: based on , Identification The braking segment is processed and the braking distance is calculated.

[0076] Drift correction module: interpolates and compensates candidate data based on the front and rear results of the reference tire and the timestamp.

[0077] Consistency screening and statistics module: executes rules such as discarding the first time, range constraint, average and confidence interval output.

[0078] Index Calculation and Reporting Module: Output , The system generates test reports based on indicators such as [list of indicators].

[0079] III. Specific Technical Route for Implementing the Method of the Invention

[0080] like Figure 2 As shown, the technical approach of this invention can be summarized as follows:

[0081] (1) First, the key boundary conditions such as vehicle-tire-load-air pressure are uniformly set through S1 so that the candidate tire and the reference tire group are in comparable working conditions.

[0082] (2) The acquisition device, trigger signal and calculation channel are calibrated by S2 to ensure that the three elements of speed, distance and trigger are synchronized and reliable;

[0083] (3) By using S3 to preprocess the tire temperature state and the braking system coordination state, the candidate tires are brought into a stable working range and the randomness of the first test is reduced.

[0084] (4) Perform a clamping braking test cycle (reference-candidate-reference) through S4, obtain the before and after reference results that can be used for drift compensation within the same cycle, and collect the braking distance according to a unified operation strategy;

[0085] (5) The candidate braking distance is drift corrected and normalized to the dry road grip index by S5, and consistency screening and statistical output are performed at the same time to achieve a more stable and comparable evaluation across time periods and sites.

[0086] IV. Implementation of Specific Steps

[0087] 4.1. Step S1: Setting the test subject and vehicle status

[0088] (1) Tire and rim matching

[0089] The candidate tires and the reference tire set are mounted onto the rims respectively, preferably with the same rim specifications, for example... After installation, dynamic balancing is performed to ensure the imbalance is within the company's internal control range (e.g., no more than [a certain value] on one side). (This is just an example; please follow your company's standards.) Tire tread depth should be measured and recorded. Excessive differences in wear between candidate and reference tires can introduce differences in effective contact area and hysteresis loss. It is recommended to control wear differences within an acceptable range within the same comparison batch.

[0090] (2) Setting and maintaining test air pressure

[0091] Set the test pressure according to the tire type: for standard tires, take... Reinforced tires After inflation, let it stand for a certain period of time (e.g., ...). To stabilize the gas temperature and pressure, the gas pressure is then checked again.

[0092] To reduce the impact of temperature on tire pressure, it is recommended to record the cold temperature of the tires. Temperature after inflation If a temperature and pressure compensation strategy is adopted, the actual measured air pressure value at that time can be used as the final record in the test report, and all tires can be adjusted to the target air pressure under similar temperature conditions.

[0093] (3) Test load setting and coaxial consistency control

[0094] The vehicle load is adjusted using a counterweight module to ensure the tire test load is within the rated load capacity. The rated load capacity here can be determined based on the tire load index or product technical documents. Use an axle load scale or four-wheel scale to measure the vertical load on each wheel. For two tires on the same axle, the load difference should not exceed [a certain value]. ,Right now:

[0095] Let the loads on the two coaxial wheels be respectively and Then it can be expressed as a relative difference.

[0096] ,

[0097] And require .

[0098] in , These represent the vertical loads on the left and right wheels of the same axle, respectively, in units of... .

[0099] (4) Vehicle technical condition inspection

[0100] Inspect the braking system (brake pad thickness, brake disc condition, brake fluid), ABS malfunction indicator lamp, wheel speed sensors, etc.; check the steering system for significant play and pulling to one side; check that the vehicle's tire alignment parameters are within the normal range. If the vehicle exhibits significant pulling to one side, it will introduce steering correction action when the ABS is activated, leading to increased fluctuations in braking distance.

[0101] (5) Refer to tire group management

[0102] The reference tire set should be assigned a fixed number and a life management file should be established, including the cumulative number of braking operations, cumulative mileage, wear depth, and thermal history. Ideally, a health check braking test should be performed on the reference tires at the beginning and end of each test day to determine if the reference tires have entered an abnormal wear or performance degradation state. If the performance of the reference tires changes significantly, they should be replaced and a new baseline should be established.

[0103] 4.2 Step S2, Instrument and Channel Calibration

[0104] (1) Equipment installation and fixing

[0105] Install the GPS speed and distance measuring device in the designated location on the vehicle (e.g., near the windshield inside the vehicle or as an external antenna on the roof), ensuring an unobstructed view, secure installation, and no displacement during forced movement. The brake trigger sensor (pedal switch / pedal force) should be correctly connected to the data acquisition device and insulated and protected against interference.

[0106] (2) Communication and record inspection

[0107] Start the acquisition software and check whether the data from each channel is updated in real time and can be recorded, including , or mileage Etc. Conduct stationary and low-speed driving tests to confirm that the speed and distance curves are continuous and without significant jumps.

[0108] (3) Time synchronization and sampling frequency setting

[0109] It is recommended to use a unified timestamp (e.g., GPS time) as the master clock to align the braking trigger signal with the speed / distance data. If there are independent clocks between different devices, a trigger synchronization action can be performed before the test (e.g., lightly applying the brakes to generate a noticeable trigger pulse) and the pulse time can be aligned in the software.

[0110] (4) Distance calculation channel consistency verification

[0111] If the device provides a direct braking distance output, it can be used with... The integrated distance is then checked for consistency. To avoid integration drift or discrepancy errors, it is preferable to use the device's distance channel. If velocity integration is used, the integration method (trapezoidal integration, etc.) must be clearly defined and fixed in the software.

[0112] (5) Setting the braking start and stop threshold

[0113] The braking distance of this invention is defined as from arrive Therefore, the following settings should be configured in the software:

[0114] Start time First crossing at a speed decreasing from high to low Threshold time;

[0115] End time Speed ​​reached for the first time And remain stable (the duration can be set, such as...) )time.

[0116] To reduce the impact of noise, small window filtering can be used (e.g., (moving average) Smoothing should be performed, but the filtering strategy should be fixed and used consistently for all experiments.

[0117] 4.3 Step S3, Tire and Braking System Pre-processing

[0118] (1) Warm-up driving

[0119] Before the test began, the vehicle was Normal driving This allows the tires to reach a stable thermal state. The purpose of preheating is to: reduce the impact of fluctuations in the viscoelastic properties of the tire's cold-state rubber compound on braking distance; and reduce the internal temperature gradient of the tire to avoid dispersion caused by sudden temperature changes in the contact patch during the first braking test. It is recommended to choose a preheating route that is the same as or similar to the test road surface, and avoid frequent rapid acceleration / braking to prevent premature temperature rise in the braking system and inconsistent break-in.

[0120] (2) Braking system break-in braking

[0121] by Perform at least two emergency braking maneuvers to trigger the ABS and maintain it until the vehicle comes to a stop. The purpose is to: ensure the brake discs / pads are in a stable frictional engagement state; eliminate first-wheel randomness caused by a cold or initial surface condition of the braking system; and match the preheated state of the candidate tires to reduce abnormal data caused by system mismatch.

[0122] (3) Consistency control of the test area

[0123] During break-in braking and formal braking, it is best to perform the tests in the same area. This is because, even at the same test site, the microstructure, pollution levels, and temperatures of different road sections may vary, leading to systematic differences in braking distance. The entry position and braking start point can be constrained using ground markings, GPS coordinates, or roadside markers.

[0124] (4) Abnormal status elimination

[0125] If any of the following situations occur during the preprocessing stage, it is recommended to pause and check: ABS cannot trigger stably or an alarm occurs; abnormal brake pedal feel (soft / hard abnormality), uneven brake wear; significant jumps or packet loss in equipment recordings; visible gravel, standing water, or contamination on the road surface. After troubleshooting, re-execute the preprocessing to avoid abnormal conditions from entering the formal data collection.

[0126] 4.4 Step S4, Braking Test Cycle and Data Acquisition

[0127] Step S4 is one of the key steps in achieving standardization and improved comparability of dry road grip evaluation. This step not only limits the test site and boundary conditions, but also explicitly captures the time drift of environmental and road conditions within the same test cycle by referencing the braking test cycle with the tires clamped at both ends, providing the necessary data foundation for subsequent drift correction in S5. The implementation method of S4 is described in detail below.

[0128] 4.1 Acceptance of Test Site and Boundary Conditions

[0129] (1) Road surface condition requirements and cleaning management

[0130] The test should be conducted on a dry, level, and clean asphalt surface. Dryness refers not only to the absence of visible water but also to the absence of significant coverage by dew, oil, or cleaning agent residue; cleanliness means the absence of obvious gravel, dust accumulation, or construction residue. A site inspection should be arranged before the test, and the braking area should be cleaned using a sweeper or manually if necessary. If strong winds or frequent vehicle traffic nearby cause dust drift, it is recommended to shorten the time span of each cycle and increase the frequency of tire clamping.

[0131] (2) Slope restrictions

[0132] The slope of the test site in any direction shall not exceed The gradient introduces a gravitational component along the driving direction, thus systematically affecting braking distance. To ensure controllable gradient, it is recommended to use: a gradient calibration report provided by the site; or to use a gradient meter to measure and record the maximum values ​​at multiple points along the driving direction and lateral. If the gradient is close to the upper limit, a two-way round-trip test should be performed whenever possible, and directional balancing should be recorded in the report (this is not mandatory in this invention, but is a preferred implementation).

[0133] (3) Adhesion coefficient Acceptance

[0134] This invention requires . Acceptance can be performed in at least one of the following ways:

[0135] Method A: Use standard friction testing equipment (such as a trailer-mounted friction tester, portable friction pendulum, etc.) to measure the braking area and take the representative value as... ;

[0136] Method B: Using a reference tire set, perform several braking operations under standard load and tire pressure, and calculate the stable range of the reference braking distance. If the reference braking distance falls within a pre-established high-adhesion asphalt reference window (formed from historical data), then... The requirements are met;

[0137] Method C: Use site certification coefficients (such as road surface grades and typical adhesion ranges provided by international test sites) in conjunction with daily spot checks.

[0138] In engineering implementation, Method B and the reference tire clamping mechanism of the present invention have a natural synergy: the reference tire is used for both drift correction and road surface adhesion acceptance, thereby reducing additional equipment investment.

[0139] (4) Wind speed and environmental monitoring

[0140] Ambient wind speed not greater than Wind can affect vehicle attitude stability and tire normal load fluctuations, especially during high-speed forced braking, potentially causing yaw or veering, and thus introducing additional distance fluctuations. It is recommended that the wind speed be near the braking area, approximately [missing information - likely a distance in meters] above the ground. Record the height measurement points and record once before each cycle; if the wind speed is close to the upper limit, it is recommended to increase the length of the speed stabilization section or reduce the number of tests in the crosswind direction.

[0141] 4.2 Organization of Braking Test Cycles

[0142] (1) Definition of loop structure

[0143] The braking test cycle of this invention includes three stages:

[0144] A reference tire set was used for one reference braking test to obtain... And record the time. ;

[0145] The candidate tire group must undergo at least three candidate braking tests to obtain... And record the time. ;

[0146] A reference tire set was used for one reference braking test to obtain... And record the time. .

[0147] In practice, to comply with the rule of discarding the first set of data, the candidate tire group can undergo four braking tests. The first test is used as discarded data (to allow the candidate tires to reach a more stable thermal state), and the second to fourth tests serve as a candidate set of at least three valid data points. Correspondingly, Numbering can be from 1 to 4, but only the parts that meet the validity criteria are selected in the S5 statistics.

[0148] (2) Refer to the tire set usage strategy

[0149] The reference tire set should be kept as stable as possible:

[0150] The reference tires should be used only for reference braking during the test day and should not be used for additional aggressive driving.

[0151] If the reference tire shows abnormal wear or temperature, the process should be paused, the reference tire replaced, and the baseline re-established.

[0152] The reference tire pressure and load should maintain the same control strategy as the candidate test to ensure that the reference results can truly reflect road and environmental drift rather than changes in the reference tire's own condition.

[0153] (3) Cycle time span control

[0154] Drift correction assumption arrive The changes in road surface / environmental conditions can be approximated linearly. To satisfy this assumption, it is recommended that the time span of each cycle be controlled within a reasonable range (e.g., (The specific timeframe depends on the stability of the site). If the cycle span is too long, linear drift may not be sufficient to characterize the actual changes. It is recommended to shorten the cycle or add a denser clamping pattern of reference-candidate-reference-candidate-reference (this is an optional enhanced implementation).

[0155] 4.3 Operating Procedures for a Single Braking Test

[0156] (1) Entry and velocity stability

[0157] The test personnel accelerated the vehicle into the braking zone. The speedometer showed the vehicle speed reached and stabilized at... Then it enters a stable speed phase. (Settings) Instead The reason is to allow for speed fluctuation margins for the driver and control system; and to ensure that the speed gradually decreases after braking begins. Sufficient data points are available to facilitate precise software positioning. It is recommended to maintain a stable speed for a certain period of time or distance, for example, by maintaining... or (This can be set according to the length of the site and driving habits, but it should be fixed within the same project).

[0158] (2) Cut off the drive torque

[0159] After the speed stabilizes, quickly shift to neutral (this can be achieved in conventional gasoline vehicles / manual or automatic transmissions via N gear), or in electric / hybrid vehicles, set the drive torque command to 0 and disable energy recovery braking torque (if the vehicle allows). The purpose of this operation is to avoid interference from drive / recovery torque on braking distance, allowing the braking distance to more purely reflect the grip capability under the combined action of tires, road surface, and ABS control.

[0160] (3) ABS triggering and pedal holding

[0161] After disengaging the accelerator, the driver firmly presses the brake pedal, causing the ABS to quickly engage and maintain its position until the vehicle comes to a complete stop. The required pedal pressure is crucial: insufficient or loose pedal force leads to unstable ABS engagement, causing fluctuations in tire longitudinal slip ratio and increased braking distance dispersion. Inconsistent pedal force application results in different ABS control modes (changes in pressure build-up / release rhythm), also causing data dispersion. To improve consistency, a pedal force sensor can be used to monitor and prompt the driver to maintain the pedal force above a certain threshold (e.g., exceeding a certain force value is considered full brake hold; the threshold is determined by vehicle characteristics). If a pedal force sensor is unavailable, the ABS engagement signal or wheel speed fluctuation characteristics can be used in after-processing to identify whether the conditions for continuous ABS engagement are met.

[0162] (4) Maintaining direction and controlling deviation

[0163] During braking, the driver should grip the steering wheel firmly and try to maintain a straight line, avoiding significant corrections. If the vehicle exhibits noticeable veer or yaw during forced braking, the following should be checked: tire assembly, alignment parameters, brake distribution, wind direction, etc. If necessary, the test direction or test site should be changed to avoid continuous testing in strong crosswinds or on steep inclines.

[0164] (5) Definition of the calculation range for braking distance

[0165] This invention requires recording vehicle movement from arrive The braking distance. The specific calculation can be performed according to the following rules:

[0166] 1) Using the velocity curve Based on, define for First equal to from high to low The moment;

[0167] 2) Definition for First equals And subsequently, it should remain no greater than a set threshold (e.g.) )continued The moment;

[0168] 3) Braking distance Can be determined by distance channel Calculated as If the device directly outputs a braking distance of 100–0, its output logic should be consistent with the above definition; if not, the unified software calculation logic should prevail.

[0169] 4.4 Validity judgment of candidate data

[0170] Initial screening can be performed during the S4 data collection phase to prevent obviously abnormal data from entering S5.

[0171] 1) Trigger validity: requires braking trigger signal exist A clear triggering event occurred nearby, and the braking remained effective for a period of time thereafter;

[0172] 2) ABS effectiveness: ABS should intervene in the main deceleration range (this can be determined by the vehicle's ABS signal or wheel speed / deceleration fluctuation characteristics).

[0173] 3) Speed ​​stability: The speed must be stable before braking. The area is near the vehicle and there are no significant acceleration or deceleration fluctuations before braking begins (e.g., the speed standard deviation does not exceed a certain threshold).

[0174] 4) Troubleshooting road surface anomalies: If there are obvious bumps, gravel strips, or oil stains in the braking section, the data can be removed by acceleration impact or driver marking and the test can be repeated.

[0175] With the above constraints, S4 can output structured data. , , Its timestamp provides a basis for implementable drift correction for S5.

[0176] Step 4.5, S5: Drift correction and grip index measurement.

[0177] Step S5 is another core step in achieving comparable evaluation across time periods and locations. Compared to the traditional method of simply averaging repeated tests, this invention introduces drift correction and outputs a normalized index in step S5, enabling the candidate tire evaluation results to align under a reference benchmark, thereby significantly reducing systematic biases caused by slow changes in environmental and road conditions. The calculation logic, variable definitions, anomaly handling, and statistical output of step S5 are fully disclosed below.

[0178] 5.1 Drift Sources and the Necessity of Correction

[0179] In actual tests, even if the requirements for slope, wind speed, and dryness and cleanliness are met, road surface adhesion and tire performance may still change slowly over time. Typical reasons include:

[0180] 1) The rise or fall of road surface temperature alters the contact state between the rubber viscoelastic window and the microscopic structure;

[0181] 2) Repeated braking by vehicles creates polishing strips or sweeping effects on the road surface, causing changes in local micro-texture and pollution status;

[0182] 3) Changes in wind direction cause dust migration;

[0183] 4) The continued evolution of tire temperature rise and changes in brake disc and pad temperature cause slight drift in brake output;

[0184] 5) The rhythm of the test personnel's operation caused differences in tire cooling / reheating.

[0185] The aforementioned drift is often slow, monotonous, or approximately linear, which is precisely the fundamental assumption of this invention's use of reference tire front and rear clamping + linear interpolation drift correction. This is achieved by obtaining [the drift correction] within the same cycle. and Corresponding reference distance , It can analyze candidate tires at various times. Measured distance Time interpolation compensation is performed to map candidate results to the same baseline state for comparison.

[0186] 5.2 Drift Correction Formula and Parameter Definition

[0187] (1) Linear drift correction formula

[0188] For candidate tires The original braking distance obtained from the second braking action Its drift correction value Calculate using the following formula:

[0189] ;

[0190] in, : Candidate tire group at time The measured number Sub-primary braking distance, in units ; : No. The drift correction results for the second candidate braking distance, in units ; Reference tire pack at time The first reference braking distance measured, in units ; Reference tire pack at time The second reference braking distance was measured, in units of ; , , The timestamp corresponding to the braking test can be obtained from GPS time or the unified time of the data acquisition system, in units of... ; : The relative time position of the candidate experiment between the reference and the reference (dimensionless).

[0191] The above formula means: if the reference tire distance is from Drift to Then it is believed that in arrive The drift between them changes linearly with time, and the candidates are in The drift amount at any given time is proportionally allocated to the total drift amount; this drift amount is then transferred from... Subtracting from the middle, we obtain the candidate distance equivalent to the reference baseline starting state.

[0192] (2) Refer to the normalization benchmark Choice

[0193] To normalize the candidate average distance to an exponent, the present invention preferably takes... for and The smaller of the two (i.e., the one with the better performance) is used as the benchmark to reduce the risk of the benchmark being too large due to accidental errors of the reference tire.

[0194] ;

[0195] in Units are .

[0196] (3) Average distance of candidates Calculation

[0197] This invention requires at least three valid data points for each group of candidate tires, and employs a rule to discard the first data point. Assume a total of [number] candidate tires were collected. Second (usually) (The first instance is discarded, then the set that satisfies the validity and consistency screening criteria is considered.) (For example Or, for subsets after removing outliers, calculate the arithmetic mean:

[0198] ;

[0199] in, The average braking distance of the candidate tire group after drift correction, in units. ; For set The number of elements in the middle is required. ; This is the single candidate distance after drift correction.

[0200] (4) Dry road surface grip index Calculation

[0201] Normalize the candidate average distance relative to the reference distance to obtain the dry road grip index:

[0202] ;

[0203] in, It is dimensionless; The larger the value, the shorter the braking distance and the stronger the grip on dry roads of the candidate tire; when The time indicates that the candidate tire and the reference tire are equivalent under the same conditions.

[0204] 5.3 Valid Data Screening and Range Consistency Constraints

[0205] (1) Reasons for and implementation of discarding the first set of data

[0206] Even after completing S3 warm-up and break-in, candidate tires may still encounter factors such as unstable tire surface and internal temperatures, unstable road sweeping effect, and inconsistent driver rhythm when first entering the candidate braking segment after entering the formal cycle. Therefore, this invention stipulates that the data from the first test of each period should be discarded. In practice, candidate data should be sorted by time in the software, and the first candidate braking test should be marked as discarded and not included in the test. Collection construction; this deprecation action should be logged to avoid arbitrary human selection.

[0207] (2) The range does not exceed constraints

[0208] To ensure the repeatability of candidate data, this invention requires that the effective data range does not exceed [a certain value]. Let the candidate data set for participating in the averaging be... Then the range Defined as:

[0209] ;

[0210] And require:

[0211] ;

[0212] in, Units are ; , These are the maximum and minimum value operators for the set, respectively; if If the candidate data is highly discrete, it indicates that the data should be processed according to the following strategy.

[0213] (3) Handling strategy when the range exceeds the limit

[0214] when In such cases, the following measures may be implemented in order of priority:

[0215] Verify boundary conditions: Check for deviations in air pressure, changes in load, sudden increases in wind speed, and the appearance of contamination zones in the braking area;

[0216] Remove significantly abnormal braking tests: If an operational abnormality can be clearly identified in a braking test (such as failure of continuous ABS intervention, delayed braking triggering, or significant steering correction), then that test will be marked as invalid and retested.

[0217] Increase the number of retests: While keeping the reference tire clamping structure unchanged, perform 1-2 retests on the candidate tire to obtain the final result. and The data set;

[0218] Restart the cycle: If referring to the tire and Large discrepancies indicate nonlinear drift or abrupt changes in site conditions. A new cycle should be restarted (by obtaining new reference results before and after) to avoid invalidation of the linear interpolation assumption.

[0219] The core principle of the above processing strategy is to prioritize ensuring the consistency of experimental conditions and the effectiveness of the reference clamp, and then achieve statistical stability through supplementary testing and elimination, rather than arbitrarily selecting data based solely on experience.

[0220] 5.4 Identification and Handling of Abnormal Tire Drift

[0221] Drift correction relies on the reliability of the results before and after using a reference tire. If the reference tire itself experiences an anomaly (e.g., sudden temperature change, pressure drift, abrupt wear change, or an abnormal operation), then... and This no longer only represents road / environmental drift, which may introduce incorrect compensation. Therefore, the present invention preferably includes a reference tire consistency check:

[0222] Calculate the reference difference ;

[0223] like Exceeding a preset threshold (e.g.) If the threshold can be determined from the company's historical data, then the reference drift is considered abnormal.

[0224] If an abnormality occurs, check the reference tire pressure, temperature, and road conditions, and perform an additional reference braking test to determine if it is an accidental operational deviation. If the abnormality persists, the data from this cycle will not be used for the final evaluation, and the cycle should be reorganized.

[0225] 5.5 Index Output, Classification and Reporting

[0226] (1) Output content

[0227] After one complete loop, the system should output at least: the original candidate distance sequence. With timestamp Reference distance , and , Corrected candidate distance Candidate average distance with range Dry road surface gripping index Environmental parameters: wind speed, road surface temperature, air temperature, slope, Acceptance methods and results.

[0228] (2) Index Interpretation

[0229] To facilitate R&D decision-making, the following interpretation can be adopted:

[0230] The candidate tire's grip is no worse than the reference tire.

[0231] The candidate tire's grip is inferior to the reference tire.

[0232] More detailed tiers can also be set according to the company's R&D goals (e.g.) (For significant improvement, etc.), but this classification belongs to the application layer strategy and does not limit the core method of the present invention.

[0233] (3) Sources of comparability across sites / lots

[0234] because It is a normalized quantity based on a reference tire, and the candidate results are corrected for drift by clamping before and after the reference. Therefore, when the same reference tire system is used in different sites or on different dates (or a traceable reference system mapping is established), the index has better horizontal comparability. Even if the reference tires are different, as long as each index is normalized to the corresponding reference and a conversion relationship is established through the bridging test of the reference system, engineering benchmarking can also be achieved.

[0235] V. Specific Application Examples

[0236] The following are reproducible road / test field verification application examples (with complete record fields, operating condition settings, data processing, and statistical standards) to demonstrate the technical effectiveness of the method of this invention in engineering practice. The listed data are measured data in terms of magnitude and fluctuation pattern. Those skilled in the art can obtain similar conclusions by implementing the steps of this invention under the same vehicle / site / equipment conditions.

[0237] 1. General Description of the Experiment

[0238] As shown in the attached figure ( Figure 1 As shown in the dry road braking distance test surface, the test section is divided into the following zones along the vehicle's direction of travel: acceleration zone, steady speed zone, braking zone, and stopping zone. The steady speed zone is used to stabilize the vehicle speed at a constant speed. Left and right; the braking zone is a unified braking area, and the starting position of each braking is constrained by road markings / cones / GPS coordinates, thereby reducing the impact of road segment differences on the results.

[0239] 1.1 Test Vehicles and Equipment

[0240] Test vehicle: Tesla Model 3 (ABS working normally, no fault alarms from wheel speed sensors and braking system).

[0241] Speed / Distance Acquisition: PBOX (GPS speed and distance measurement), speed and distance sampling frequency Braking trigger signal Sampling frequency .

[0242] Test speed range: (Depend on Threshold crossing determined).

[0243] Test site: High-adhesion asphalt dry pavement (slope) Wind speed The adhesion level meets ).

[0244] 1.2 Tires and Boundary Conditions

[0245] Specification: Wheel rim: .

[0246] Test tire pressure: Standard tire (The test was reviewed before and after, and the deviation was controlled within...) Inside).

[0247] Test load: based on the tire's rated load capacity The load difference between the two wheels on the same axle is set to not exceed [a certain value]. .

[0248] Preprocessing: driving Preheating; Emergency braking First break-in (ABS triggered and held until stopped).

[0249] 1.3 Key Calculations of this Invention

[0250] (1) Drift correction:

[0251] ;

[0252] in: , The reference tires are respectively at , Reference braking distance measured at all times; For candidate tires in The original braking distance measured at any given time; This represents the candidate braking distance after drift correction.

[0253] (2) Reference normalization benchmark:

[0254] ;

[0255] (3) Average distance of candidates (discard the first one, at least 3 are valid):

[0256] ;

[0257] (4) Dry road grip index:

[0258] ;

[0259] in It is dimensionless; the larger the value, the stronger the candidate tire's grip on dry roads.

[0260] 2. Application Example 1

[0261] 2.1 Test conditions

[0262] Time: Morning (09:40–10:05)

[0263] Wind speed: Road surface temperature:

[0264] Reference tire group: R (fixed number reference tire)

[0265] Candidate tire: A (Option A to be evaluated).

[0266] 2.2 Original Data Recording (Reference-Candidate-Reference Clamping Loop)

[0267] Set the time span of this cycle to approximately ,Pick , The candidate braking occurred in the following situations: .

[0268] Table 1 Application Example 1: Original Data and Correction Results of Clamping Cycle in Scheme A ( Braking distance

[0269]

[0270] Where the reference drift is Taking A-2 as an example, the drift term is... Therefore .

[0271] 2.3 Consistency and Index Results

[0272] After discarding A-1, the effective set ,satisfy .

[0273] Effective correction range:

[0274] Candidate average correction distance:

[0275] Reference to the normalized benchmark

[0276] Dry road grip index:

[0277] Conclusion (Example 1): Within a single cycle, this invention can complete reference clamping—drift correction—exponential output without increasing the complexity of the equipment, and the effective data range is significantly smaller than... The proof method is both operable and reproducible.

[0278] 3. Application Example 27)

[0279] This example is used to verify that when changes in road surface temperature, dust, and tire thermal state between morning and afternoon cause an overall drift in braking distance, comparing only the original braking distance will result in incomparability across different time periods; however, the method employed by this invention... It can be significantly stabilized.

[0280] 3.1 Experimental Design

[0281] Candidate tire: A

[0282] Morning cycle: Same as Example 1 (09:40–10:05)

[0283] Afternoon cycle: 14:10–14:35 (road surface temperature is higher, and overall tire braking distance is increased)

[0284] Other boundary conditions (air pressure, load, speed strategy, braking zone) remain consistent.

[0285] 3.2 Afternoon cycle of raw data (Tire A)

[0286] The reference tires showed more noticeable drifting in the afternoon: , , The original data for candidate A is as follows:

[0287] Table 2 Application Example 2: Afternoon Cycle Data and Correction Results for Scheme A

[0288]

[0289] The calculation yields:

[0290] ;

[0291] ;

[0292] .

[0293] 3.3 Quantitative Comparison of Technical Effects (Across Time Periods)

[0294] The morning and afternoon results are listed side by side:

[0295] Table 3. Cross-Time Period Comparison: Original Braking Distance vs. Invention Index (Considering Only the Original Braking Distance)

[0296]

[0297] Further statistical analysis was conducted on the dispersion of all valid raw data (6 times) across time periods and the corresponding exponential distribution:

[0298] The original distance standard deviation is approximately ;

[0299] The standard deviation of the index is approximately ;

[0300] The dispersion decreased by approximately: .

[0301] Conclusion: When environmental and road conditions cause overall braking distance drift, simply comparing the original braking distance will result in significant incomparability across different time periods; this invention provides a reference clamping and drift correction output. This allows the results of the same tire to almost overlap across time periods, significantly improving repeatability and comparability.

[0302] 4. Application Example 3: Testing Two Tire Solutions at Different Time Periods

[0303] This example simulates a common business scenario: Plan A is tested in the morning, while Plan B is tested in the afternoon due to scheduling. If only the original braking distance is compared, it's easy to mistakenly interpret increased distance due to worsened road conditions as decreased tire performance. This invention avoids this misjudgment.

[0304] 4.1 Test Subjects

[0305] Candidate Tire A: Baseline Solution

[0306] Candidate Tire B: Improvement Plan (Optimization of tread compound and stiffness distribution, with the goal of improving dry grip)

[0307] Reference tire R: Fixed reference tire set

[0308] 4.2 Afternoon Loop Data for Option B

[0309] Refer to the tire specifications for the afternoon benchmark of Example 2: , The original and corrected data for Scheme B are as follows:

[0310] Table 4 Application Example 3: Afternoon Cycle Data and Correction Results for Scheme B

[0311]

[0312] The calculation yields:

[0313] ;

[0314] ;

[0315] .

[0316] 4.3 Comparison with the conclusions of Scheme A

[0317] Original effective mean of Option A in the morning: (Example 1)

[0318] Original effective mean of Option B in the afternoon: (Table 4, Means of B-2 to B-4)

[0319] If only comparing the raw means: This could lead to a misjudgment that option B is worse.

[0320] However, the index of this invention is adopted: , .

[0321] That is, the dry grip improvement of Option B relative to the reference tire is approximately (The magnitude of the index increase) can still give consistent engineering conclusions when tested at different time periods.

[0322] Conclusion: This invention significantly improves the accuracy of cross-time period comparisons, avoids misjudging environmental drift as tire performance differences, and improves the sensitivity to discriminate moderate improvements (approximately 2%).

[0323] 5. Comparative Example

[0324] Comparative Example 1: Without using reference clamping and index, only the original braking distance is used.

[0325] Given the scheduling conditions of Option A in the morning and Option B in the afternoon, the original distance comparison will directly lead to an incorrect ranking (misjudging B as the inferior one), as shown in the comparison conclusion of Application Example 3, which illustrates that conventional methods are difficult to solve the problem of incomparability across time periods.

[0326] Comparative Example 2: Single-shot reference only (pre-reference), no linear drift correction performed.

[0327] Taking Solution A of Application Example 2 (afternoon) as an example: If only the preceding reference is used... And without considering subsequent drift, then

[0328] ;

[0329] This could lead to a misjudgment that Scheme A is inferior to the reference tire. However, this invention, through front and rear reference clamping and linear drift correction, achieves... This aligns more closely with the fact that the same tire should maintain consistency under the same benchmark, indicating that drift correction is necessary to suppress time-varying errors within a cycle.

[0330] VI. Technical Effects

[0331] Through the above application examples and comparative examples, it can be seen that: This invention, through reference-candidate-reference clamping cycles and drift correction, explicitly quantifies and compensates for the systematic drift caused by changes in road surface temperature, cleanliness, and vehicle / tire thermal state within the same test day, thereby reducing the difference in braking distance between the original braking distance and the evaluation results of the same tire across time periods. The above converges to an exponential difference of approximately Within this range, the comparability and repeatability are significantly improved; compared to traditional methods that only output the original braking distance, the output of this invention is significantly improved. It possesses a normalized scale attribute, ensuring stable ranking across different time periods and batch testing conditions, avoiding misinterpretation of environmental changes as tire performance differences; the performance improvement of candidate tires is approximately... Even at the scale of the test, the present invention can still maintain stable and repeatable differentiation results in cross-time period tests, indicating that it has higher discrimination sensitivity in R&D benchmarking, competitor evaluation and formula iteration.

[0332] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. A method for evaluating the dry road grip capability of passenger car tires, characterized in that, The method includes the following steps: S1, Test Object and Vehicle Status Setting: Install the candidate tire on at least one axle of the test vehicle, and set the tire test pressure and vehicle test load so that the tire test load accounts for 60% to 90% of the tire's rated load capacity, and the load difference between the two tires on the same axle does not exceed 10%; S2, Instrument and Channel Calibration: Set up the braking distance test equipment and complete the communication and data acquisition channel calibration. The data acquisition channel should include at least vehicle speed, vehicle travel distance and braking trigger signal. S3, Tire and Braking System Pre-treatment: Before the formal data collection, drive the vehicle at 60km / h for 10 minutes to warm up the candidate tires, and perform at least 2 emergency braking operations at 100km / h to complete the tire-rim-braking system break-in pre-treatment. S4, Braking Test Cycle and Data Acquisition: A braking test cycle is conducted on a dry, flat, and clean asphalt road surface with a slope of no more than 2% in any direction. The road surface adhesion coefficient... Not less than 0.7, and the ambient wind speed is not greater than 5 m / s; The braking test cycle includes: completing a reference braking test using a reference tire set to obtain a reference braking distance. Subsequently, candidate braking distances were obtained by completing at least three candidate braking tests with the candidate tire group. Finally, a reference braking test was conducted using the same set of reference tires to obtain the reference braking distance. ; Each braking test involved bringing the vehicle into a stable speed range and stabilizing it at 105 km / h before cutting off the drive torque and triggering the ABS until the vehicle came to a stop. The braking distance was calculated as the distance the vehicle traveled from 100 km / h to 0 km / h. S5, Drift Correction and Grip Index Calculation: Braking distance for each candidate braking test. Linear drift correction is performed based on the two reference braking distances from the reference tire set before and after, resulting in the corrected candidate braking distance. : ； After discarding the first data from the candidate braking test, the remaining at least three Take the arithmetic mean Further calculation of the dry road grip index , ； and with This serves as an evaluation result of the candidate tires' dry road grip capability.

2. The method according to claim 1, characterized in that: In step S1, the tire test load is achieved by setting a counterweight on the test vehicle, and the counterweight includes the driver's mass and / or the passenger's counterweight mass; and the load difference between the two tires on the same axle is characterized by the ratio of the difference in the vertical load of the two tires to their average vertical load. And / or, in step S1, the test pressure of the standard tire is 250 kPa, and the test pressure of the reinforced tire is 290 kPa.

3. The method according to claim 1, characterized in that: In step S2, the brake trigger signal includes a brake pedal switch signal and / or a brake pedal force signal, and the sampling frequency is not less than 200Hz.

4. The method according to claim 1, characterized in that: In step S3, the at least two emergency braking actions trigger the ABS within the braking range where the vehicle speed drops from 100 km / h to 0 km / h and continue until the vehicle stops.

5. The method according to claim 1, characterized in that: In step S4, the "cut-off of drive torque" is achieved by at least one of the following methods: shifting into neutral; or setting the energy recovery braking torque to 0 and the drive motor torque command to 0 in electric drive / hybrid operation. And / or, in step S4, the braking starting position of each braking test satisfies the requirement that the lateral deviation does not exceed 0.3m and the longitudinal deviation does not exceed 2.0m, so as to limit the braking to occur in the same braking area.

6. The method according to claim 1, characterized in that: In step S5, during the calculation First, test the candidate braking system. Perform consistency screening to ensure that participants in the average... The range does not exceed 0.5m; wherein, the range is the The difference between the maximum and minimum values; And / or, in step S5, according to The dry road grip capabilities of candidate tires are classified, and the classification thresholds include at least: when When determining that the candidate tire is not inferior to the reference tire, The candidate tire is determined to be inferior to the reference tire.

7. A dry road grip evaluation system for passenger car tires, used to perform the method described in any one of claims 1 to 6, characterized in that, include: The system includes a tire assembly and operating condition setting module, a data acquisition module, a brake test cycle control module, a drift correction module, and a grip index calculation module; the drift correction module is used to calculate the grip index based on... , and calculate The index calculation module is used to calculate the index based on... and calculate .

8. The system according to claim 7, characterized in that: The data acquisition module includes a GPS speed and distance measurement unit and a brake trigger acquisition unit. The brake trigger acquisition unit includes a brake pedal switch and / or a brake pedal force sensor. And / or, the braking test cycle control module includes a speed stabilization control unit for prompting or constraining the vehicle speed to stabilize at 105 km / h, and a torque cut-off control unit for cutting off the drive torque before braking.

9. A computer-readable storage medium having a computer program or instructions stored thereon, characterized in that, When the computer program or instructions are executed by the processor, they implement steps S3-S5 of the method according to any one of claims 1-6.

10. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by the processor, they implement steps S3-S5 of the method according to any one of claims 1-6.

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