A static tire longitudinal force partition fitting method and device

Abstract

The present invention discloses a method and device for fitting static tire longitudinal force partitioning. The method includes: conducting a static longitudinal rigidity test on a test tire to obtain multiple sets of longitudinal forces and longitudinal displacements in the load loading stage and the load unloading stage, plotting a scatter diagram of test data of longitudinal force and longitudinal displacement with the longitudinal displacement as the abscissa and the longitudinal force as the ordinate; dividing the load loading stage and the load unloading stage of the test data scatter diagram according to at least two preset load intervals to form multiple partitions, and determining the longitudinal rigidity of each partition based on the longitudinal force and longitudinal displacement of each partition; fitting a longitudinal rigidity curve based on the longitudinal rigidity of each partition; wherein, the load of the preset load interval is less than the preset maximum target load, thereby further improving the accuracy of the static tire longitudinal rigidity result and making it more convenient for tire characteristic analysis.

Description

Technical Field

[0001] This application relates to the field of tire mechanical characteristic data processing, and more specifically, to a method and device for fitting a static tire longitudinal force partition. Background Art

[0002] When a tire bears a load and is subjected to a longitudinal force, the relationship between the longitudinal force and the longitudinal displacement is called longitudinal stiffness, which affects the driving and braking performance of the tire.

[0003] In the national standard, there are two methods for calculating the longitudinal stiffness of a tire. One is the two-point method, where the longitudinal stiffness Kx = δFx / δSx = (Fx2–Fx1) / (Sx2–Sx1), Fx2 is the reference longitudinal force × 30% × 9.8m / s + 250N, Fx1 is the reference longitudinal force × 30% × 9.8m / s - 250N, Sx2 is the longitudinal displacement corresponding to Fx2, and Sx1 is the longitudinal displacement corresponding to Fx1.

[0004] The other is to extract the longitudinal force and longitudinal displacement data segments of 30% - 60% of the vertical force in the longitudinal force and longitudinal displacement curve, and use the least squares method to fit a unary linear equation according to the formula y = b0 + b1x, and take the slope of the straight line as the longitudinal stiffness of the tire.

[0005] However, the above two methods only obtain the test data in the vertical force loading stage, without considering the test data in the vertical force unloading stage. The accuracy of the obtained static tire longitudinal stiffness is low, and the obtained longitudinal stiffness is a single-point value, which is not convenient for analyzing the characteristics of the tire.

[0006] Therefore, how to improve the accuracy of the static tire longitudinal stiffness result and make it more convenient for tire characteristic analysis is a technical problem to be solved at present. Summary of the Invention

[0007] The present invention discloses a method for fitting a static tire longitudinal force partition to solve the technical problems of low accuracy of the static tire longitudinal stiffness result and inconvenience for tire characteristic analysis in the prior art. The method includes:

[0008] Assemble the test tire onto the test rim, inflate the test tire to a preset air pressure and park it for a first preset duration;

[0009] Fix the combination of the test tire and the test rim to the test rigid machine and make the test tire contact the contact platform;

[0010] Apply a vertical force to the test tire at a first preset moving speed until each preset target load is reached and finally the preset maximum target load is reached. Among them, after each preset target load or the preset maximum target load is reached and maintained for a second preset duration, apply a longitudinal force to the contact platform at a second preset moving speed, and determine the longitudinal displacement when relative slip occurs between the contact platform and the test tire;

[0011] Unload the vertical force on the test tire from the preset maximum target load until it is reduced to each of the preset target loads respectively. Among them, after each reduction to a preset target load and maintaining the second preset duration, apply a longitudinal force to the contact platform at the second preset moving speed, and determine the longitudinal displacement when relative slip occurs between the contact platform and the test tire;

[0012] Take the longitudinal displacement as the abscissa and the longitudinal force as the ordinate to plot a scatter diagram of the test data of the longitudinal force and the longitudinal displacement;

[0013] According to at least two preset load intervals, divide the load loading stage and the load unloading stage of the test data scatter diagram respectively to form multiple partitions, and determine the longitudinal rigidity of each partition according to the longitudinal force and the longitudinal displacement of each partition;

[0014] Fit and generate a longitudinal rigidity curve according to the longitudinal rigidity of each partition;

[0015] Among them, the load of the preset load interval is less than the preset maximum target load.

[0016] In some embodiments of the present application, determining the longitudinal rigidity of each partition according to the longitudinal force and the longitudinal displacement of each partition is specifically:

[0017] Perform separate cubic polynomial fittings on the longitudinal force and the longitudinal displacement of each partition. Among them, assume that the cubic polynomial fitting formula is y = ax

[0017] ,

[0021] ,

[0016] , 2 ,

[0020] ,

[0019] ,

[0018] , , , 2 , 3 , , , + bx 2 + cx + d, and obtain the numerical values of the constants a, b, and c;

[0018] Take the derivative of the cubic polynomial fitting formula to obtain the derivative formula y' = 3ax 2 + 2bx + c, and substitute the numerical values of the constants a, b, and c into the derivative formula to determine the longitudinal rigidity of each partition;

[0019] Among them, y is the longitudinal force, x is the longitudinal displacement, and y' is the longitudinal rigidity.

[0020] In some embodiments of the present application, the preset load intervals include 0% - 30%, 30% - 60%, and 60% - 90% of the preset maximum target load.

[0021] In some embodiments of the present application, the preset maximum target load includes 80%, or 100%, or 120% of the maximum load of the test tire.

[0022] In some embodiments of the present application, before vertically loading the test tire with a first preset moving speed until each preset target load is reached, the method further includes:

[0023] Vertically load the test tire with the first preset moving speed until a pre-test load is reached, unload after maintaining for a third preset duration, repeat the preset number of times for pre-testing, and after the pre-test is completed, inflate the test tire to the preset air pressure.

[0024] Correspondingly, the present invention also proposes a static tire longitudinal force partition fitting device, and the device includes:

[0025] A contact platform that accommodates the test tire and contacts the test tire;

[0026] A loading module for vertically loading the test tire and applying a longitudinal force to the contact platform;

[0027] A positioning module for determining the longitudinal displacement when relative slippage occurs between the contact platform and the test tire;

[0028] A controller for:

[0029] When receiving a test instruction sent by a user, control the loading module to vertically load the test tire with a first preset moving speed until each preset target load is reached and finally reach the preset maximum target load. Wherein, after each preset target load or the preset maximum target load is reached and maintained for a second preset duration, control the loading module to apply a longitudinal force to the contact platform with a second preset moving speed, and determine the longitudinal displacement through the positioning module when relative slippage occurs between the contact platform and the test tire;

[0030] Control the loading module to unload the vertical force of the test tire from the preset maximum target load until it is respectively reduced to each preset target load. Wherein, after each reduction to a preset target load and maintaining the second preset duration, control the loading module to apply a longitudinal force to the contact platform with the second preset moving speed, and determine the longitudinal displacement through the positioning module when relative slippage occurs between the contact platform and the test tire;

[0031] Taking the longitudinal displacement as the abscissa and the longitudinal force as the ordinate, plot a scatter diagram of the test data of the longitudinal force and the longitudinal displacement;

[0032] According to at least two preset load intervals, divide the load loading stage and the load unloading stage of the test data scatter diagram respectively to form multiple partitions, and determine the longitudinal rigidity of each partition according to the longitudinal force and the longitudinal displacement of each partition.

[0033] Generate a longitudinal rigidity curve by fitting according to the longitudinal rigidity of each partition;

[0034] Wherein, the load in the preset load range is less than the preset maximum target load.

[0035] In some embodiments of the present application, the controller is specifically configured to:

[0036] Perform separate cubic polynomial fittings on the longitudinal force and longitudinal displacement of each partition. Among them, let the cubic polynomial fitting formula be y = ax 3 + bx 2 + cx + d, and obtain the numerical values of constants a, b, and c;

[0037] Take the derivative of the cubic polynomial fitting formula to obtain the derivative formula y' = 3ax 2 + 2bx + c, and substitute the numerical values of constants a, b, and c into the derivative formula to determine the longitudinal rigidity of each partition;

[0038] Wherein, y is the longitudinal force, x is the longitudinal displacement, and y' is the longitudinal rigidity.

[0039] In some embodiments of the present application, the preset load range includes 0%-30%, 30%-60%, and 60%-90% of the preset maximum target load.

[0040] In some embodiments of the present application, the preset maximum target load includes 80%, or 100%, or 120% of the maximum load of the test tire.

[0041] In some embodiments of the present application, the controller is further configured to:

[0042] When receiving a pre-test instruction sent by the user, control the loading module to load a vertical force on the test tire at the first preset moving speed until the pre-test load is reached, unload after maintaining for a third preset duration, and repeat the preset number of times for pre-testing.

[0043] By applying the above technical solutions, perform a static longitudinal rigidity test on the test tire, obtain multiple groups of longitudinal forces and longitudinal displacements in the load loading stage and the load unloading stage, use the longitudinal displacement as the abscissa and the longitudinal force as the ordinate to draw a scatter plot of the test data of the longitudinal force and longitudinal displacement; divide the load loading stage and the load unloading stage of the test data scatter plot according to at least two preset load ranges to form multiple partitions, determine the longitudinal rigidity of each partition according to the longitudinal force and longitudinal displacement of each partition; generate a longitudinal rigidity curve by fitting according to the longitudinal rigidity of each partition; wherein, the load in the preset load range is less than the preset maximum target load, thereby further improving the accuracy of the static tire longitudinal rigidity result and making it more convenient for tire characteristic analysis. Description of the Drawings

[0044] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the accompanying drawings required for description in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0045] Figure 1 It shows a schematic flow chart of a static tire longitudinal force zoning fitting method proposed in an embodiment of the present invention;

[0046] Figure 2 It shows a schematic diagram of a tire coordinate system in an embodiment of the present invention;

[0047] Figure 3 It shows a schematic diagram of a tire static longitudinal rigidity test in an embodiment of the present invention;

[0048] Figure 4 It shows a schematic structural diagram of a static tire longitudinal force zoning fitting device proposed in an embodiment of the present invention. Specific embodiments

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0050] The embodiments of the present application provide a static tire longitudinal force zoning fitting method. By processing the test data of the longitudinal force in each zone, the test data in the load loading stage and the load unloading stage can be highly accurately fitted into a smooth curve for calculating tire characteristic values, benchmark analysis, or for tire model identification, with the characteristics of high accuracy, good repeatability, and high efficiency. As Figure 1 shown, it includes the following steps:

[0051] Step S101, assemble the test tire onto the test rim, inflate the test tire to a preset air pressure and park it for a first preset duration.

[0052] In this embodiment, first conduct a tire longitudinal rigidity test, and determine the final static longitudinal rigidity result according to the test data.

[0053] Pre-select tires with good appearance quality as test tires, then assemble the test tires onto the test rims, inflate the test tires to a preset air pressure and park them for a first preset duration.

[0054] In some embodiments of the present application, the preset air pressure can be 250 kPa or 290 kPa, and the first preset duration is not less than 24 h. Those skilled in the art can flexibly set different preset air pressures and first preset durations according to actual needs.

[0055] Step S102: Fix the combination of the test tire and the test rim to the test rigid machine, and make the test tire contact the contact platform.

[0056] In this embodiment, the test rigid machine is used to perform longitudinal rigidity testing on the test tire, and the test tire contacts the contact platform during the test. The contact platform can completely accommodate the part of the tire in contact and has sufficient roughness. The contact platform has sufficient stroke to meet the test requirements, and the contact platform and its support structure have sufficient rigidity. When a vertical force is applied to the tire, the contact platform does not deform longitudinally, transversely, or bend.

[0057] Step S103: Apply a vertical force to the test tire at a first preset moving speed until each preset target load is reached and finally the preset maximum target load is reached. Among them, after each preset target load or the preset maximum target load is reached and maintained for a second preset duration, a longitudinal force is applied to the contact platform at a second preset moving speed, and the longitudinal displacement is determined when relative slip occurs between the contact platform and the test tire.

[0058] In this embodiment, the directions of the vertical force and the longitudinal force correspond to the tire coordinate system. As Figure 2 shown, it is a schematic diagram of the tire coordinate system. The vertical force corresponds to the Z'-axis of the tire coordinate system, and the longitudinal force corresponds to the X'-axis of the tire coordinate system. The tire coordinate system is a right-handed rectangular coordinate system with the tire contact center as the origin. The X'-axis is the intersection line of the tire center plane and the road plane, and the advancing direction of the tire center plane is positive; the Z'-axis is the plumb line, and the upward direction is positive; the Y'-axis is in the road plane, and the direction is determined according to the right-hand rule.

[0059] Multiple preset target loads are preset in advance. As Figure 3 shown, a vertical force Fz is applied to the test tire at a first preset moving speed until each preset target load is reached and finally the preset maximum target load is reached. After each preset target load or the preset maximum target load is reached, to improve the test accuracy, it is maintained for a second preset duration, and then a longitudinal force Fx is applied to the contact platform at a second preset moving speed. The longitudinal displacement Sx is determined when relative slip occurs between the contact platform and the test tire, so that multiple sets of longitudinal forces Fx and longitudinal displacements Sx corresponding to the load loading stage and each preset target load and the preset maximum target load can be obtained.

[0060] Optionally, the first preset moving speed is 50 mm / min, the second preset duration is 1 min, and the second preset moving speed is 30 mm / min to 50 mm / min. Those skilled in the art can flexibly set different first preset moving speeds, second preset durations, and second preset moving speeds according to actual needs.

[0061] In order to improve the accuracy of test data, in some embodiments of the present application, before vertically loading the test tire with the first preset moving speed until each preset target load is reached, the method further includes:

[0062] Vertically load the test tire with the first preset moving speed until the pre-test load is reached, unload after maintaining the third preset duration, repeat the preset number of times for pre-testing, and after the pre-testing is completed, inflate the test tire to the preset air pressure.

[0063] In this embodiment, before officially performing the longitudinal rigidity test on the test tire, perform a preset number of pre-tests. After determining that there is no problem with the test tire and the test rigidity machine, inflate the test tire to the preset air pressure for the official test.

[0064] Optionally, the pre-test load is 80% of the maximum load of the test tire, and the third preset duration can be 5 s.

[0065] Step S104, unload the vertical force on the test tire from the preset maximum target load until it is respectively reduced to each preset target load. Wherein, after each reduction to a preset target load and maintaining the second preset duration, apply a longitudinal force to the contact platform at the second preset moving speed, and determine the longitudinal displacement when relative slip occurs between the contact platform and the test tire.

[0066] In this embodiment, as Figure 3 shown, after completing the test in the load loading stage, enter the load unloading stage. Unload the vertical force Fz on the test tire from the preset maximum target load until it is respectively reduced to each preset target load. When each reduction reaches a preset target load, maintain the second preset duration, then apply a longitudinal force Fx to the contact platform at the second preset moving speed, and determine the longitudinal displacement Sx when relative slip occurs between the contact platform and the test tire, so as to obtain multiple sets of longitudinal forces Fx and longitudinal displacements Sx corresponding to each preset target load in the load unloading stage.

[0067] Step S105, taking the longitudinal displacement as the abscissa and the longitudinal force as the ordinate, plot the scatter diagram of the test data of the longitudinal force and the longitudinal displacement.

[0068] In this embodiment, based on multiple sets of longitudinal forces and longitudinal displacements obtained in steps S103 and S104, a scatter plot of test data of longitudinal force and longitudinal displacement is plotted with the longitudinal displacement as the abscissa and the longitudinal force as the ordinate.

[0069] Step S106: Divide the load application stage and the load unloading stage of the test data scatter plot according to at least two preset load intervals to form multiple partitions, and determine the longitudinal rigidity of each partition according to the longitudinal force and longitudinal displacement of each partition.

[0070] In this embodiment, the load of the preset load interval is less than the preset maximum target load. The load application stage of the test data scatter plot is divided according to the preset load interval to form multiple partitions, and the load unloading stage of the test data scatter plot is divided according to the preset load interval to form multiple partitions, and then the longitudinal rigidity of each partition is determined according to the test data of each partition.

[0071] Optionally, the preset load intervals in the load application stage and the load unloading stage are the same.

[0072] In order to accurately determine the longitudinal rigidity of each partition, in some embodiments of the present application, the longitudinal rigidity of each partition is determined according to the longitudinal force and longitudinal displacement of each partition. Specifically:

[0073] Separate cubic polynomial fittings are performed on the longitudinal force and longitudinal displacement of each partition. Among them, let the cubic polynomial fitting formula be y = ax 3 + bx 2 + cx + d, and the numerical values of constants a, b, and c are obtained;

[0074] The cubic polynomial fitting formula is differentiated to obtain the derivative formula y' = 3ax 2 + 2bx + c, and the longitudinal rigidity of each partition is determined after substituting the numerical values of constants a, b, and c into the derivative formula;

[0075] Among them, y is the longitudinal force, x is the longitudinal displacement, and y' is the longitudinal rigidity.

[0076] It can be understood that both y and Figure 3 Fx in are longitudinal forces, and both x and Figure 3 Sx in are longitudinal displacements.

[0077] It should be noted that the solutions of the above embodiments are only a specific implementation solution proposed by the present application, and other methods for determining the longitudinal rigidity of each partition according to the longitudinal force and longitudinal displacement of each partition all fall within the protection scope of the present application.

[0078] Step S107: Fit a longitudinal rigidity curve according to the longitudinal rigidity of each partition.

[0079] In this embodiment, a smooth longitudinal stiffness curve is generated by fitting the longitudinal stiffness of each partition. The longitudinal stiffness curve can be used to calculate tire characteristic values, conduct benchmark analysis, or be used for tire model identification.

[0080] Optionally, in some embodiments of the present application, the preset load range includes 0%-30%, 30%-60%, and 60%-90% of the preset maximum target load.

[0081] It can be understood that each partition in the load application stage of the test data scatter plot is divided according to 0%-30%, 30%-60%, and 60%-90% of the preset maximum target load, forming three partitions; each partition in the load unloading stage of the test data scatter plot is also divided according to 0%-30%, 30%-60%, and 60%-90% of the preset maximum target load, forming another three partitions. Therefore, a total of six partitions are formed.

[0082] Optionally, in some embodiments of the present application, the preset maximum target load includes 80%, or 100%, or 120% of the maximum load of the test tire.

[0083] By applying the above technical solutions, a static longitudinal stiffness test is performed on the test tire to obtain multiple sets of longitudinal forces and longitudinal displacements in the load application stage and the load unloading stage. Taking the longitudinal displacement as the abscissa and the longitudinal force as the ordinate, a test data scatter plot of the longitudinal force and the longitudinal displacement is plotted; according to at least two preset load ranges, the load application stage and the load unloading stage of the test data scatter plot are respectively divided to form multiple partitions, and the longitudinal stiffness of each partition is determined according to the longitudinal force and the longitudinal displacement of each partition; a longitudinal stiffness curve is generated by fitting the longitudinal stiffness of each partition; wherein, the load in the preset load range is less than the preset maximum target load, thereby further improving the accuracy of the static tire longitudinal stiffness result and making it more convenient for tire characteristic analysis.

[0084] An embodiment of the present application also proposes a static tire longitudinal force partition fitting device, as Figure 4 shown, the device includes:

[0085] A contact platform 10 that houses the test tire and contacts the test tire;

[0086] A loading module 20 for applying a vertical force to the test tire and applying a longitudinal force to the contact platform 10;

[0087] A positioning module 30 for determining the longitudinal displacement when relative slippage occurs between the contact platform 10 and the test tire;

[0088] A controller 40 for:

[0089] When receiving a test instruction sent by a user, the control loading module 20 is controlled to load a vertical force on the test tire at a first preset moving speed until each preset target load is reached and finally the preset maximum target load is reached. Among them, after each preset target load or the preset maximum target load is reached and maintained for a second preset duration, the control loading module 20 is controlled to apply a longitudinal force to the contact platform 10 at a second preset moving speed, and the longitudinal displacement is determined by the positioning module 30 when relative slippage occurs between the contact platform 10 and the test tire;

[0090] The control loading module 20 is controlled to unload the vertical force on the test tire from the preset maximum target load until it is respectively reduced to each preset target load. Among them, after each reduction to a preset target load and maintaining the second preset duration, the control loading module 20 is controlled to apply a longitudinal force to the contact platform 10 at the second preset moving speed, and the longitudinal displacement is determined by the positioning module 30 when relative slippage occurs between the contact platform 10 and the test tire;

[0091] Taking the longitudinal displacement as the abscissa and the longitudinal force as the ordinate, a scatter plot of the test data of the longitudinal force and the longitudinal displacement is drawn;

[0092] According to at least two preset load intervals, the load loading stage and the load unloading stage of the test data scatter plot are respectively divided to form multiple partitions, and the longitudinal rigidity of each partition is determined according to the longitudinal force and the longitudinal displacement of each partition;

[0093] A longitudinal rigidity curve is generated by fitting according to the longitudinal rigidity of each partition;

[0094] Among them, the load of the preset load interval is less than the preset maximum target load.

[0095] In a specific application scenario of the present application, the controller 40 is specifically used for:

[0096] Separate cubic polynomial fittings are performed on the longitudinal force and the longitudinal displacement of each partition. Among them, assuming the cubic polynomial fitting formula is y = ax 3 + bx 2 + cx + d, and the numerical values of the constants a, b, and c are obtained;

[0097] The cubic polynomial fitting formula is differentiated to obtain the derivative formula y' = 3ax 2 + 2bx + c, and the longitudinal rigidity of each partition is determined after substituting the numerical values of the constants a, b, and c into the derivative formula;

[0098] Among them, y is the longitudinal force, x is the longitudinal displacement, and y' is the longitudinal rigidity.

[0099] In a specific application scenario of the present application, the preset load range includes 0%-30%, 30%-60%, and 60%-90% of the preset maximum target load.

[0100] In a specific application scenario of the present application, the preset maximum target load includes 80%, or 100%, or 120% of the maximum load of the test tire.

[0101] In a specific application scenario of the present application, the controller 40 is further configured to:

[0102] When receiving a pre-test instruction sent by a user, control the loading module 20 to load a vertical force on the test tire at the first preset moving speed until reaching a pre-test load, unload after maintaining for a third preset duration, and repeat a preset number of times for pre-testing.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present application.

Claims

1. A method for fitting longitudinal force partitioning of a static tire, characterized in that, The method includes: Mount the test tire on the test rim, inflate the test tire to a preset air pressure and park it for a first preset duration; Fix the combination of the test tire and the test rim to the test rigid machine and make the test tire contact the contact platform; Apply a vertical force to the test tire at a first preset moving speed until each preset target load is reached and finally the preset maximum target load is reached. Among them, after each preset target load or the preset maximum target load is reached and maintained for a second preset duration, apply a longitudinal force to the contact platform at a second preset moving speed, and determine the longitudinal displacement when relative slip occurs between the contact platform and the test tire; Unload the vertical force on the test tire from the preset maximum target load until it is reduced to each of the preset target loads respectively. Among them, after each reduction to a preset target load and maintaining the second preset duration, apply a longitudinal force to the contact platform at the second preset moving speed, and determine the longitudinal displacement when relative slip occurs between the contact platform and the test tire; Taking the longitudinal displacement as the abscissa and the longitudinal force as the ordinate, plot the scatter diagram of the test data of the longitudinal force and the longitudinal displacement; Divide the load loading stage and the load unloading stage of the test data scatter diagram according to at least two preset load intervals to form multiple partitions, and determine the longitudinal rigidity of each partition according to the longitudinal force and the longitudinal displacement of each partition; Generate a longitudinal rigidity curve by fitting the longitudinal rigidities of each partition; Among them, the load of the preset load interval is less than the preset maximum target load.

2. The method according to claim 1, characterized in that, Determine the longitudinal rigidity of each partition according to the longitudinal force and the longitudinal displacement of each partition, specifically: Separate third-order polynomial fittings are performed on the longitudinal forces and longitudinal displacements of each partition. Among them, the third-order polynomial fitting formula is set as y = ax 3 + bx 2 + cx + d, and the numerical values of the constants a, b, and c are obtained; Derive the cubic polynomial fitting formula to obtain the derivative formula y' = 3ax 2 + 2bx + c. Substitute the values of the constants a, b, and c into the derivative formula to determine the longitudinal rigidity of each partition; Among them, y is the longitudinal force, x is the longitudinal displacement, and y' is the longitudinal rigidity.

3. The method according to claim 1, characterized in that The preset load interval includes 0%-30%, 30%-60% and 60%-90% of the preset maximum target load.

4. The method according to claim 1, characterized in that The preset maximum target load includes 80%, or 100%, or 120% of the maximum load of the test tire.

5. The method according to claim 1, wherein Before applying a vertical force to the test tire at a first preset moving speed until each preset target load is reached, the method further includes: Apply a vertical force to the test tire at the first preset moving speed until a pre-test load is reached, unload after maintaining for a third preset duration, repeat the preset number of times for pre-test, and after the pre-test is completed, inflate the test tire to the preset air pressure.

6. A static tire longitudinal force partition fitting device, characterized in that The device includes: A contact platform that accommodates the test tire and contacts the test tire; A loading module for applying a vertical force to the test tire and a longitudinal force to the contact platform; A positioning module for determining the longitudinal displacement when relative slip occurs between the contact platform and the test tire; A controller for: When receiving a test instruction sent by a user, control the loading module to apply a vertical force to the test tire at a first preset moving speed until each preset target load is reached and finally the preset maximum target load is reached. Among them, after each preset target load or the preset maximum target load is reached and maintained for a second preset duration, control the loading module to apply a longitudinal force to the contact platform at a second preset moving speed, and determine the longitudinal displacement through the positioning module when relative slippage occurs between the contact platform and the test tire; Control the loading module to unload the vertical force on the test tire from the preset maximum target load until it is respectively reduced to each preset target load. Among them, after each reduction to a preset target load and maintaining the second preset duration, control the loading module to apply a longitudinal force to the contact platform at the second preset moving speed, and determine the longitudinal displacement through the positioning module when relative slippage occurs between the contact platform and the test tire; Taking the longitudinal displacement as the abscissa and the longitudinal force as the ordinate, plot a scatter diagram of the test data of the longitudinal force and the longitudinal displacement; According to at least two preset load intervals, divide the load loading stage and the load unloading stage of the test data scatter diagram respectively to form multiple partitions, and determine the longitudinal rigidity of each partition according to the longitudinal force and the longitudinal displacement of each partition; Fit and generate a longitudinal rigidity curve according to the longitudinal rigidity of each partition; Among them, the load of the preset load interval is less than the preset maximum target load.

7. The device according to claim 6, characterized in that, The controller is specifically used for: Separate cubic polynomial fittings are performed on the longitudinal forces and longitudinal displacements of each partition. Among them, let the cubic polynomial fitting formula be y = ax 3 + bx 2 + cx + d, and the numerical values of the constants a, b, and c are obtained; Derive the cubic polynomial fitting formula to obtain the derivative formula y' = 3ax 2 + 2bx + c. Substitute the values of the constants a, b, and c into the derivative formula to determine the longitudinal rigidity of each partition; Among them, y is the longitudinal force, x is the longitudinal displacement, and y' is the longitudinal rigidity.

8. The device according to claim 6, characterized in that The preset load interval includes 0%-30%, 30%-60%, and 60%-90% of the preset maximum target load.

9. The device according to claim 6, characterized in that, The preset maximum target load includes 80%, or 100%, or 120% of the maximum load of the test tire.

10. The device according to claim 6, characterized in that, The controller is further used for: When receiving a pre-test instruction sent by a user, control the loading module to apply a vertical force to the test tire at the first preset moving speed until the pre-test load is reached, unload after maintaining for a third preset duration, and repeat the preset number of times for pre-testing.

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