Testing and identification methods of tire cornering stiffness

Abstract

The present invention discloses a method for testing and identifying tire cornering stiffness, comprising preparing for a cornering stiffness test and testing; collecting test data according to a set sampling frequency; collecting multiple periodic data, drawing a lateral force-slip angle curve based on the periodic data, performing curve fitting on the curve, and taking a linear term coefficient as a first cornering stiffness value; evaluating the difference in the cornering stiffness values ​​of multiple periods and optimizing the difference; obtaining output cornering characteristic test data through cornering characteristic test preparation and cornering characteristic testing, and thereby obtaining a second cornering stiffness value and a return stiffness value; performing model identification on model parameters based on the output slip angle characteristic test data; and correcting the model identification through the first cornering stiffness. The present invention can control tire temperature and tread wear during the test, obtain high-precision cornering stiffness, and has a positive effect on the simulation of working conditions such as the high-speed center area and angular pulse of the whole vehicle.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile tire lateral dynamics, and in particular to a method for testing and identifying tire cornering stiffness. Background Art

[0002] In recent years, as competition in the automotive industry has intensified and vehicle development cycles have continued to shorten, virtual development, virtual matching, and virtual tuning have gradually become the primary means of vehicle development to adapt to new market and development cycle demands. Virtual simulation is playing an increasingly important role in vehicle development, and the demand for simulation of vehicle handling stability, ride comfort, and NVH is steadily increasing. High-precision vehicle simulation technology is an inevitable trend. As the sole component that transmits force and torque between the vehicle and the ground, accurate modeling of tire characteristics is a critical component of vehicle simulation.

[0003] Vehicle handling stability simulation has always been a key part of the vehicle driving experience. Tires play an important role in the simulation of vehicle handling stability. In particular, the tire's cornering stiffness has a significant impact on the vehicle's mid-position response. In addition to meeting the basic vehicle simulation requirements, more accurate tire cornering stiffness values ​​are extremely important for simulating specific working conditions.

[0004] The design field of the present invention is the field of automobile tire lateral dynamics. It aims to use a reasonable test and identification method to determine the accurate acquisition of the key parameter affecting the handling stability performance of the automobile - the cornering stiffness, so as to improve the reliability and accuracy in vehicle dynamics simulation and analysis, and meet the requirements of high-precision automobile simulation. At present, most tire testing work is to obtain the tire's cornering characteristics through a complete test in one go. Due to the high test speed, the tire will produce a sharp change in temperature during the test, resulting in the slope of the test curve near the cornering angle of 0 becoming unreliable, and the cornering stiffness cannot be accurately obtained. The present invention improves on the original test method by reducing the test loading rate and changing the test range to obtain data, ensuring the temperature stability of the tire during the test. At the same time, the least squares method is used to identify the nonlinear parameters of the cornering stiffness under different loads, and finally obtain a complete tire cornering stiffness function to meet the use requirements.

[0005] Vehicle handling stability is a crucial factor influencing vehicle safety and driving pleasure. Since tires are the only part of a vehicle that contacts the road, vehicle handling stability is largely dependent on tire cornering characteristics. Currently, tire handling stability testing generally refers to the requirements of the Magic Formula and UniTire tire models. For tire cornering characteristics, test data must be obtained within a slip angle range of ±12°, ±15°, or ±20° (generally speaking, a wider range results in more accurate identification model results). Earlier, tests for this operating condition used the fixed-point method and low-speed testing. That is, the lateral force and return torque results were tested at a fixed sideslip angle at low speed. This test efficiency was too low, often requiring a long time to conduct the test and process the relevant data, which was not conducive to commercial modeling. Subsequently, high-speed six-component force testing equipment emerged, which greatly improved the test efficiency by conducting tests using a sinusoidal sweep test method. The side slip test under the same operating condition only took a few minutes. However, this test method could not obtain a good side slip stiffness value. The reason is that the tire temperature and tread wear changes cannot be controlled during the high-speed sweep process, and the influence of temperature on side slip characteristics is very severe. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for testing and identifying tire cornering stiffness. In order to obtain accurate cornering stiffness data, the present invention proposes a new method based on current tests, which can not only efficiently complete the corresponding tests, but also control tire temperature and tread wear during the test process. The high-precision cornering stiffness obtained can be used to simplify the establishment of vehicle models to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above-mentioned object, the present invention provides the following technical solution: a method for testing and identifying tire cornering stiffness, comprising:

[0008] The tires are tested on a six-component force test bench;

[0009] performing a cornering stiffness test preparation and a cornering stiffness test on the tire;

[0010] Collect data from the lateral stiffness test according to the set sampling frequency;

[0011] The cornering stiffness test collects multiple periodic data, plots a lateral force-slip angle curve based on the periodic data, performs curve fitting on the curve, and takes the linear term coefficient as the first cornering stiffness value;

[0012] Performing data analysis using mean square error to evaluate the differences in multiple values ​​of the first cornering stiffness obtained over multiple cycles, and performing optimization to ensure that the data fluctuations are within a reasonable range. Otherwise, repeating the cornering stiffness test preparation and cornering stiffness testing;

[0013] Through cornering characteristic test preparation and cornering characteristic test, output cornering characteristic test data is obtained, and the second cornering stiffness value and the return stiffness value are obtained based on this;

[0014] According to the output sideslip angle characteristic test data, the model parameters are identified;

[0015] Model identification is corrected using the first cornering stiffness.

[0016] Furthermore, through cornering characteristic test preparation and cornering characteristic test, output cornering characteristic test data is obtained, and thereby a second cornering stiffness value and a return stiffness value are obtained, including:

[0017] Set up the cornering stiffness test procedure and determine the tire pressure, load and roll angle parameters required for the test;

[0018] Provide triangular wave loading according to the required sideslip angle range;

[0019] Data is collected for the cornering characteristic test at the set sampling frequency to obtain data curves of lateral force, aligning moment, and cornering angle under different loads.

[0020] Output cornering characteristic test data and calculate tire lateral force and righting moment curves for different slip angles under different loads. Select data within the slip angle range of ±1 degree, perform curve fitting on it, and take the linear term coefficient as the second cornering stiffness value and righting stiffness value.

[0021] Furthermore, based on the output cornering characteristic test data, check whether the cornering angle loading curve and the control curve coincide with each other. If they do not coincide, adjust the PID parameters and re-prepare for the cornering characteristic test and the cornering characteristic test. PID is the test bench control parameter.

[0022] Furthermore, based on the output sideslip angle characteristic test data, model identification is performed on the model parameters, including a model identification formula. Using the MF6.2 tire model, the model identification formula is as follows:

[0023] F y =F yo (α,γ,Fz)

[0024] F y0 =D y sin[C y arctan{B y α y -E y (B y α y -arctan(B y αy ))}]+S vy

[0025] Where F y is the lateral force, F yo is the lateral force function, α, α y is the slip angle, γ is the roll angle, F z is the vertical load, B y 、C y 、D y and E y are model parameters, namely stiffness factor, shape factor, peak factor and curvature factor, S vy is the vertical offset parameter.

[0026] Furthermore, the first cornering stiffness data is substituted into the model identification formula for correction, and the model identification formula is derived to obtain the following formula:

[0027] F' y0 =D y sin'[C y arctan{B y α y -E y (B y α y -arctan(B y α y ))}]*C y arctan'

[0028] {B y α y -E y (B y α y -arctan(B y α y ))}*B y (1-E y (1-arctan'(B y α y )))

[0029] Furthermore, when the sideslip angle is zero, the slope of the curve at the zero sideslip angle can be obtained by substituting the derivative into the curve, that is, the cornering stiffness, which is expressed as: K y =B y C y D y

[0030] The model uses the magic formula to express the numerical calculation formula of the cornering stiffness:

[0031] K y =K y0(1-p ky3 |γ y |)γ3

[0032]

[0033] By identifying the calculated cornering stiffness, λ Ky parameter.

[0034] where K y is the cornering stiffness function expression, K y0 is the cornering stiffness factor when the roll angle is 0, γ y is the actual roll angle, γ3 is the roll angle scaling factor, P ky1 Indicates the influence factor of the maximum cornering stiffness, p py1 Indicates the factor of maximum cornering stiffness changing with tire pressure, F z0 Indicates rated load, dp i is the infinitesimal element of tire pressure, F z is the actual load, P ky2 is the influence factor of the cornering stiffness changing with load, p py2 The influence factor of the cornering stiffness relative to the tire pressure as it changes with load, λ Fz0 Vertical load scaling factor, λ Ky Cornering stiffness scaling factor.

[0035] Furthermore, the corrected model identification parameter file is output as a result to the full vehicle simulation for full vehicle simulation with small lateral acceleration.

[0036] Furthermore, the preparation for the cornering stiffness test and the cornering stiffness test also include:

[0037] Set up the cornering stiffness test procedure, determine the tire pressure, load, and roll angle parameters required for the test, and apply triangular wave loading according to the required slip angle range;

[0038] Repeat the forward / reverse rotation test N times. After the test, if the tire temperature fluctuation is greater than 10° C., readjust the tire temperature to the set temperature.

[0039] Furthermore, before testing the tire on the tire six-component force test bench, it also includes: adjusting the tire pressure of the tire to the tire pressure required for the test, eliminating the internal stress of the tire, and making the temperature of the tire reach a set temperature.

[0040] Further, including:

[0041] A test run procedure is set up, where the tire runs from low speed to high speed for T1 minute under rated load, followed by T2 minutes of reciprocating motion at a small slip angle to ensure uniform tire heating and eliminate internal tire stress.

[0042] Apply a small load and a small speed to cool the tire until the tread temperature reaches the set temperature.

[0043] Compared with the existing technology, the beneficial effects of the present invention are: based on the current testing problems, this patent proposes a new method, which can not only complete the corresponding tests efficiently, but also control the tire temperature and tread wear during the test process, and obtain high-precision cornering stiffness, which can be used to simplify the establishment of vehicle models and solve the problem of low accuracy of some working conditions in vehicle simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Flowchart of a method for testing and identifying tire cornering stiffness according to an embodiment of the present invention;

[0045] Figure 2 A technical roadmap for a method for testing and identifying tire cornering stiffness in an embodiment of the present invention;

[0046] Figure 3 is a side slip angle loading curve diagram in an embodiment of the present invention;

[0047] Figure 4 2 is a comparison chart of the cornering stiffness test methods before and after in an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0049] In the description of the present invention, unless otherwise specified, "plurality" means two or more; terms such as "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," and "tail" indicate positions or relationships based on those shown in the accompanying drawings. These terms are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0050] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; and direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0051] Referring to the accompanying drawings, the present invention provides a technical solution: a method for testing and identifying tire cornering stiffness, comprising the following steps:

[0052] S100, testing the tire on the tire six-component force test bench;

[0053] S200, preparing for and testing the tire for a cornering stiffness test;

[0054] S300, collecting data for the lateral stiffness test according to a set sampling frequency;

[0055] S400, collecting multiple periodic data for a cornering stiffness test, plotting a lateral force-slip angle curve based on the periodic data, performing curve fitting on the curve, and taking a linear term coefficient as a first cornering stiffness value;

[0056] Specifically, the first cornering stiffness value is substituted into the model identification formula to correct it.

[0057] S500, performing data analysis using mean square error to evaluate differences in multiple first cornering stiffness values ​​obtained over multiple cycles, and performing optimization to ensure that fluctuations in the data results are within a reasonable range. Otherwise, repeating cornering stiffness test preparation and cornering stiffness testing;

[0058] S600: Obtain output cornering characteristic test data through cornering characteristic test preparation and cornering characteristic test, and thereby obtain a second cornering stiffness value and a return stiffness value;

[0059] S700, performing model identification on model parameters according to the output sideslip angle characteristic test data;

[0060] S800: Correct model identification using the first cornering stiffness.

[0061] In the above-mentioned embodiment, in order to obtain accurate cornering stiffness data, this patent proposes a new method based on the current testing problems. This method can not only efficiently complete the corresponding test, but also control the tire temperature and tread wear during the test process. The high-precision cornering stiffness obtained can be used to simplify the establishment of the vehicle model and solve the problem of low accuracy of some working conditions in the whole vehicle simulation.

[0062] Optionally, cornering characteristic test data is obtained through cornering characteristic test preparation and cornering characteristic test, and the second cornering stiffness value and the righting stiffness value are obtained therefrom, including:

[0063] Set up the cornering stiffness test procedure and determine the tire pressure, load and roll angle parameters required for the test;

[0064] Provide triangular wave loading according to the required sideslip angle range;

[0065] Data is collected for the cornering characteristic test at the set sampling frequency to obtain data curves of lateral force, aligning moment, and cornering angle under different loads.

[0066] Output cornering characteristic test data and calculate tire lateral force and righting moment curves for different slip angles under different loads. Select data within the slip angle range of ±1 degree, perform curve fitting on it, and take the linear term coefficient as the second cornering stiffness value and righting stiffness value.

[0067] Optionally, based on the output slip characteristic test data, check whether the slip angle loading curve and the control curve coincide with each other. If they do not coincide, adjust the PID parameters and perform slip characteristic test preparation and slip characteristic test again.

[0068] Optionally, based on the output sideslip angle characteristic test data, model identification is performed on the model parameters, including a model identification formula. Using the MF6.2 tire model, the model identification formula is as follows:

[0069] F y =F yo (α,γ,Fz)

[0070] F y0 =D y sin[C y arctan{B y α y -E y (B y α y -arctan(B y α y ))}]+S vy

[0071] Where F y is the lateral force, F yo is the lateral force function, α, α y is the slip angle, γ is the roll angle, F z is the vertical load, B y 、C y 、D y and E yare model parameters, namely stiffness factor, shape factor, peak factor and curvature factor, S vy is the vertical offset parameter.

[0072] Optionally, the first cornering stiffness data is substituted into the model identification formula for correction, and the model identification formula is derived to obtain the following formula:

[0073] F' y0 =D y sin'[C y arctan{B y α y -E y (B y α y -arctan(B y α y ))}]*C y arctan'

[0074] {B y α y -E y (B y α y -arctan(B y α y ))}*B y (1-E y (1-arctan'(B y α y )))

[0075] Alternatively, when the slip angle is zero, the slope of the curve at zero slip angle can be obtained by substituting it into the derivative, i.e., the cornering stiffness, which is expressed as: K y =B y C y D y

[0076] The model uses the magic formula to express the numerical calculation formula of the cornering stiffness:

[0077] K y =K y0 (1-p ky3 |γ y |)γ3

[0078]

[0079] By identifying the calculated cornering stiffness, λ Ky parameter.

[0080] where K y is the cornering stiffness function expression, K y0is the cornering stiffness factor when the roll angle is 0, γ y is the actual roll angle, γ3 is the roll angle scaling factor, P ky1 Indicates the influence factor of the maximum cornering stiffness, p py1 Indicates the factor of maximum cornering stiffness changing with tire pressure, F z0 Indicates rated load, dp i is the infinitesimal element of tire pressure, F z is the actual load, P ky2 is the influence factor of the cornering stiffness changing with load, p py2 The influence factor of the cornering stiffness relative to the tire pressure as it changes with load, λ Fz0 Vertical load scaling factor, λ Ky Cornering stiffness scaling factor.

[0081] Optionally, the corrected model identification parameter file is output as a result to the full vehicle simulation for full vehicle simulation with small lateral acceleration.

[0082] Optionally, preparing for and testing the cornering stiffness test may also include:

[0083] Set up the cornering stiffness test procedure and determine the tire pressure, load and roll angle parameters required for the test, such as Figure 3 As shown, a triangular wave load is given according to the sideslip angle range required by the test;

[0084] Repeat the forward / reverse rotation test N times. After the test, if the tire temperature fluctuation is greater than 10° C., readjust the tire temperature to the set temperature.

[0085] In the above embodiment, preferably, the test is repeated three times (forward / reverse). After the test, it is ensured that the temperature fluctuation is no more than 10°C. If the temperature difference is large, the tire cooling test is repeated to bring the temperature back to the set temperature range.

[0086] Optionally, before testing the tire on the tire six-component force test bench, the method further includes: adjusting the tire pressure of the tire to the tire pressure required for the test, eliminating the internal stress of the tire, and allowing the temperature of the tire to reach a set temperature.

[0087] In the above embodiment, preparatory work is required before the test. The tire-rim assembly is installed on the tire six-component force test bench, the tire pressure is adjusted, and the six-component force test bench is started. Since the residual and concentrated stresses in the tire during the manufacturing and molding process cannot be completely eliminated, it is advisable to conduct a trial run on the tire to eliminate the stress before the formal test.

[0088] Optionally include:

[0089] A test run procedure is set up, where the tire runs from low speed to high speed for T1 minute under rated load, followed by T2 minutes of reciprocating motion at a small slip angle to ensure uniform tire heating and eliminate internal tire stress.

[0090] Apply a small load and a small speed to cool the tire until the tread temperature reaches the set temperature.

[0091] In the above embodiment, a trial run program is set. Preferably, the tire runs at a speed from a low speed of 20 km / h to a high speed of 120 km / h under rated load for 10 minutes, followed by a 1-minute reciprocating motion at a small slip angle within a range of -1° to 1° to ensure uniform heating of the tire and eliminate internal stress of the tire. Since the tread temperature rise caused by heat generation will affect the test results of the lateral stiffness, the tire needs to be cooled subsequently; that is, a small load of 500N and a small speed of 30 km / h are applied to cool the tire until the tread temperature meets the temperature setting requirement of 30°C-35°C.

[0092] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for testing and identifying tire cornering stiffness, characterized in that: include: The tires are tested on a six-component force test bench; performing a cornering stiffness test preparation and a cornering stiffness test on the tire; Collect data from the lateral stiffness test according to the set sampling frequency; The cornering stiffness test collects multiple periodic data, plots a lateral force-slip angle curve based on the periodic data, performs curve fitting on the curve, and takes the linear term coefficient as the first cornering stiffness value; Performing data analysis using mean square error to evaluate the differences in multiple values ​​of the first cornering stiffness obtained over multiple cycles, and performing optimization to ensure that the data fluctuations are within a reasonable range. Otherwise, repeating the cornering stiffness test preparation and cornering stiffness testing; Through cornering characteristic test preparation and cornering characteristic test, output cornering characteristic test data is obtained, and the second cornering stiffness value and the return stiffness value are obtained based on this; According to the output sideslip angle characteristic test data, the model parameters are identified; Model identification is corrected using the first cornering stiffness.

2. A method for testing and identifying tire cornering stiffness according to claim 1, characterized in that: Through cornering characteristic test preparation and cornering characteristic testing, output cornering characteristic test data is obtained, and the secondary cornering stiffness value and the return stiffness value are obtained based on this, including: Set up the cornering stiffness test procedure and determine the tire pressure, load and roll angle parameters required for the test; Provide triangular wave loading according to the required sideslip angle range; Data is collected for the cornering characteristic test at the set sampling frequency to obtain data curves of lateral force, aligning moment, and cornering angle under different loads. Output the cornering characteristic test data, and calculate the tire lateral force and righting moment curves for different slip angles under different loads. Select data within the slip angle range of ±1 degree, perform curve fitting on it, and take the linear term coefficient as the second cornering stiffness value and the righting stiffness value.

3. A method for testing and identifying tire cornering stiffness according to claim 2, characterized in that: Based on the output cornering characteristic test data, check whether the cornering angle loading curve and the control curve coincide. If they do not, adjust the PID parameters and repeat the cornering characteristic test preparation and cornering characteristic test. PID is the test bench control parameter.

4. A method for testing and identifying tire cornering stiffness according to claim 1, characterized in that: Based on the output sideslip angle characteristic test data, model identification is performed on the model parameters, including the model identification formula. The MF6.2 tire model is used, and the model identification formula is as follows: F y =F yo (α,γ,Fz) F y0 =D y sin[C y silver{B y α y -AND y (B y α y -arctane(B y α y ))}]+S vy Where F y is the lateral force, F yo is the lateral force function, α, α y is the slip angle, γ is the roll angle, F z is the vertical load, B y 、C y 、D y and E y are model parameters, namely stiffness factor, shape factor, peak factor and curvature factor, S vy is the vertical offset parameter.

5. A method for testing and identifying tire cornering stiffness according to claim 4, characterized in that: Substituting the first cornering stiffness data into the model identification formula for correction, and derivatizing the model identification formula, the following formula is obtained: F' y0 =D y sin'[C y arctan{B y α y -AND y (B y α y -arctan(B y α y ))}]*C y arctan'{B y α y -AND y (B y α y -arctan(B y α y ))}*B y (1-E y (1-arctan'(B y α y )))。 6. A method for testing and identifying tire cornering stiffness according to claim 5, characterized in that: When the sideslip angle is zero, the slope of the curve at the zero sideslip angle can be obtained by substituting it into the derivative curve, that is, the cornering stiffness, which is expressed as: K y =B y C y D y The model uses the magic formula to express the numerical calculation formula of the cornering stiffness: K y =K y0 (1-p ky3 |c y |)c3 By identifying the calculated cornering stiffness, λ Ky parameter; Where K y is the cornering stiffness function expression, K y0 is the cornering stiffness factor when the roll angle is 0, γ y is the actual roll angle, γ3 is the roll angle scaling factor, P ky1 Indicates the influence factor of the maximum cornering stiffness, p py1 Indicates the factor of maximum cornering stiffness changing with tire pressure, F z0 Indicates rated load, dp i is the infinitesimal element of tire pressure, F z is the actual load, P ky2 is the influence factor of the cornering stiffness changing with load, p py2 The influence factor of the cornering stiffness relative to the tire pressure as it changes with load, λ Fz0 Vertical load scaling factor, λ Ky Cornering stiffness scaling factor.

7. A method for testing and identifying tire cornering stiffness according to claim 6, characterized in that: The modified model identification parameter file is output as a result to the full vehicle simulation for full vehicle simulation with small lateral acceleration.

8. The method for testing and identifying tire cornering stiffness according to claim 1, characterized in that: Preparation for and testing of cornering stiffness tests, including: Set up the cornering stiffness test procedure, determine the tire pressure, load, and roll angle parameters required for the test, and apply triangular wave loading according to the required slip angle range; Repeat the forward / reverse test N times. After the test, if the tire temperature fluctuation is greater than 10°C, readjust the tire temperature to the set temperature.

9. The method for testing and identifying tire cornering stiffness according to claim 1, characterized in that: Before testing the tire on the high-speed six-component force test bench, the method further includes: adjusting the tire pressure of the tire to the tire pressure required for the test, eliminating the internal stress of the tire, and making the temperature of the tire reach a set temperature.

10. A method for testing and identifying tire cornering stiffness according to claim 9, characterized in that: include: A test run procedure is set up, where the tire runs from low speed to high speed for T1 minute under rated load, followed by T2 minutes of reciprocating motion at a small slip angle to ensure uniform tire heating and eliminate internal tire stress. Apply a small load and a small speed to cool the tire until the tread temperature reaches the set temperature.

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