Tire transient response data calculating method, data processing method, tire designing method, vehicle motion predicting method, and tire cornering characteristic evaluation method and evaluation device therefor

• US 20070233352A1
• Filed: 03/30/2007
• Published: 10/04/2007
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Yokohama Rubber Company Limited
• Original Assignee: Yokohama Rubber Company Limited
• Inventors: Miyashita, Naoshi, Hanada, Ryoji, Seto, Hideki, Kabe, Kazuyuki
• Granted Patent: US 7,912,683 B2
• Time in Patent Office: Days
• US Class Current: 701/82
• CPC Class Codes: B60W 40/12 related to parameters of the vehicle itself , e.g. tyre models
• CPC Class Codes: G01M 17/022 the tyre co-operating with rotatable rolls

Abstract

Tire transient response data during cornering with a slip angle is calculated based on a tire dynamic model. A deformation response of a tread part in the tire dynamic is set as a first-order-lag response. The value of the transient response parameter is initialized, to define the first-order-lag response. The time-series data of the transient response of the slip angle between the tread part and a road surface in the tire dynamic model is obtained by computing a convolution integral of the defined response function of the first-order-lag response with a time gradient of the time-series data of the slip angle. A value of a lateral force is calculated by using the tire dynamic model based on the obtained time-series data of the transient response of the slip angle. Accordingly, the transient response data is calculated, and a value of the transient response parameter is obtained.

Claims

1. A tire transient response data calculating method, for calculating tire transient response data during cornering with a slip angle provided as time-series data based on a tire dynamic model constituted by using at least one tire dynamic element parameter, comprising the steps of:

acquiring a value of at least one tire dynamic element parameter constituting the tire dynamic model, thereby making the tire dynamic model operable;

calculating the time-series data of a transient response of the slip angle between a tread part and a road surface in the tire dynamic model by computing a convolution integral of a response function of a first-order-lag response of the tire dynamic model with a time gradient of the time-series data of the slip angle provided to the tire dynamic model, the first-order-lag response specifying a deformation response of the tread part during cornering; and

calculating, as transient response data during cornering, output data of at least one of a lateral force and self-aligning torque by using the tire dynamic model based on the calculated time-series data of the transient response of the slip angle.

2. The tire transient response data calculating method according to claim 1, wherein the time-series data of the slip angle provided to the tire dynamic model is modified by torsional deformation of the tire dynamic model which is caused by a self-aligning torque during cornering, and the modified time-series data is used for calculating the time-series data of the transient response of the slip angle.

3. The tire transient response data calculating method according to claim 2, wherein the torsional deformation of the tire which is generated by the self-aligning torque is represented by dividing a convolution integral of a response function of a first-order-lag response of the tire dynamic model with a time gradient of previous time-series data of the self-aligning torque, by a value of a stiffness contained in the tire dynamic model, the first-order-lag response specifying a deformation response of a side part during cornering.

4. The tire transient response data calculating method according to claim 1, wherein the output data calculated using the tire dynamic model comprises data of the lateral force corrected by lateral bending deformation of a belt part generated by the lateral force.

5. The tire transient response data calculating method according to claim 4, wherein the lateral bending deformation of the belt part generated by the lateral force is represented by computing a convolution integral of a response function of a first-order-lag response of the tire dynamic model with a time gradient of previous time-series data of the generated lateral force, the first-order-lag response specifying a deformation response of the belt part during cornering.

6. A tire transient response data calculating method, for calculating tire transient response data during cornering with a slip angle provided as time-series data based on a tire dynamic model, comprising the steps of:

previously acquiring values of at least one of a lateral force and a self-aligning torque in a steady state from actual measurement of a tire by providing a tire with the time-series data of the slip angle varying across at least a range between 0 degrees and a predetermined angle as the slip angle in the steady state;

calculating the time-series data of a transient response of the slip angle between a tread part and a road surface in the tire dynamic model by computing a convolution integral of a response function of a first-order-lag response of the tire dynamic model with a time gradient of the time-series data of the slip angle provided to the tire, the first-order-lag response specifying a deformation response of the tread part during cornering; and

acquiring, as transient response data during cornering, the time-series data of at least one of the lateral force and self-aligning torque in a transient state by obtaining a value of at least one of the lateral force and self-aligning torque in the steady state corresponding to each value of the calculated time-series data of the transient response of the slip angle.

7. A data processing method, in which a deformation response of a tread part which specifies a transient response during cornering in a tire dynamic model is set as a first-order-lag response to calculate a value of a transient response parameter that defines the first-order-lag response, comprising the steps of:

previously acquiring measurement data of the transient response of at least one of a lateral force and self-aligning force during cornering of a tire by providing the tire with the time-series data of a slip angle as a measurement condition;

setting a value of the transient response parameter initially and defining a response function of the first-order-lag response, thereby making the tire dynamic model operable, thereby making the tire dynamic model operable;

performing simulating calculation including;

obtaining the time-series data of a transient response of the slip angle between the tread part and a road surface in the tire dynamic model by computing a convolution integral of the defined response function of the first-order-lag response with a time gradient of the time-series data of the slip angle provided to the tire as the measurement condition;

calculating, as the time-series data of at least one of the lateral force and the self-aligning torque in a transient state during cornering, values of at least one of the lateral force and the self-aligning torque by using the tire dynamic model based on the obtained time-series data of the transient response of the slip angle; and

obtaining a sum of square residuals between the calculated time-series data of at least one of the lateral force and self-aligning torque and the measurement data of the tire, repeating the simulating calculation while correcting the set value of the transient response parameter until the sum of square residuals becomes minimum, and determining the value of the transient response parameter obtained when the sum of square residuals becomes minimum as the value of the transient response parameter that defines the first-order-lag response.

8. A data processing method, in which a deformation response of a tread part which specifies a transient response during cornering in a tire dynamic model is set as a first-order-lag response to calculate a value of a transient response parameter that defines the first-order-lag response, comprising the steps of:

previously acquiring measurement data of the transient response of at least one of a lateral force and a self-aligning torque during cornering of a tire by providing the tire with the time-series data of a slip angle, which varies across at least a range between 0 degrees and a predetermined angle while the slip angle reciprocates, as a measurement condition;

setting the value of the transient response parameter initially and defining a response function of the first-order-lag response, thereby making the tire dynamic model operable;

performing regression calculation including;

obtaining the time-series data of a transient response of the slip angle between the tread part and a road surface in the tire dynamic model by computing a convolution integral of the response function of the first-order-lag response with a time gradient of the time-series data of the slip angle provided to the tire as the measurement condition;

subjecting a characteristic curve, which represents a values of at least one of the lateral force and the self-aligning torque with respect to values of the obtained time-series data of the transient response of the slip angle, to least square regression into a single smooth curve by using a curve function; and

obtaining a sum of square residuals between the least square regression curve obtained by the least square regression and the characteristic curve; and

repeating the regression calculation while correcting the set value of the transient response parameter until the calculated sum of square residuals becomes minimum, and determining the value of the transient response parameter obtained when the sum of square residuals becomes minimum as the value of the transient response parameter that defines the first-order-lag response.

9. A tire transient response data calculating method, for calculating tire transient response data during braking/driving with a slip ratio in a longitudinal direction of a tire provided as time-series data based on a tire dynamic model constituted by using at least one tire dynamic element parameter, comprising the steps of:

acquiring a value of the tire dynamic element parameter constituting the tire dynamic model, thereby making the tire dynamic model operable;

calculating the time-series data of a transient response of the slip ratio between a tread part and a road surface in the tire dynamic model by computing a convolution integral of a response function of a first-order-lag response of the tire dynamic model with a time gradient of the time-series data of the slip ratio provided to the tire dynamic model, the first-order-lag response specifying a deformation response of the tread part during braking/driving,; and

calculating, as transient response data during braking/driving, output data of a longitudinal force by using the tire dynamic model based on the time-series data of the transient response of the slip ratio.

10. A tire transient response data calculating method, for calculating tire transient response data during braking/driving with a slip ratio in a longitudinal direction of a tire provided as time-series data based on a tire dynamic model, comprising the steps of:

previously acquiring values of a longitudinal force in a steady state from actual measurement of the tire when the time-series data of the slip ratio varying across at least a range between 0 degrees and a predetermined slip ratio is provided as the slip ratio in the steady state;

calculating the time-series data of a transient response of the slip ratio between a tread part and a road surface in the tire dynamic model by computing a convolution integral of a response function of a first-order-lag response of the tire dynamic model with a time gradient of the time-series data of the slip ratio, the first-order-lag response specifying a deformation response of the tread part during braking/driving; and

acquiring, as transient response data during braking/driving, the time-series data of the longitudinal force in a transient state by obtaining a value of the longitudinal force in the steady state corresponding to each value of the calculated time-series data of the transient response of the slip ratio.

11. A data processing method, in which a deformation response of a tread part which specifies a transient response during braking/driving of a tire in a tire dynamic model is set as a first-order-lag response to calculate a value of a transient response parameter that defines the first-order-lag response, comprising the steps of:

previously acquiring measurement data of the transient response of a longitudinal force during braking/driving of a tire by providing the tire with the time-series data of a slip ratio, which varies across at least a range between 0 degrees and a predetermined slip ratio while the slip ratio reciprocates, as a measurement condition;

setting the value of the transient response parameter initially and defining a response function of the first-order-lag response, thereby making the tire dynamic model operable;

performing regression calculation including;

obtaining the time-series data of a transient response of the slip ratio between the tread part and a road surface in the tire dynamic model by computing a convolution integral of the response function of the first-order-lag response with a time gradient of the time-series data of the slip ratio provided to the tire as the measurement condition;

subjecting a characteristic curve, which represents values of the longitudinal force with respect to values of the obtained time-series data of the transient response of the slip ratio, to least square regression into a single smooth curve by using a curve function; and

obtaining a sum of square residuals between the least square regression curve obtained by the least square regression and the characteristic curve; and

repeating the regression calculation while correcting the set value of the transient response parameter until the calculated sum of square residuals becomes minimum, and determining the value of the transient response parameter obtained when the sum of square residuals becomes minimum as the value of the transient response parameter that defines the first-order-lag response.

12. A data processing method, in which a deformation response of a tread part which specifies a transient response during braking/driving in a tire dynamic model constituted by using at least one tire dynamic element parameter is set as a first-order-lag response to calculate a value of a transient response parameter that defines the first-order-lag response, comprising the steps of:

previously acquiring measurement data of the transient response of a longitudinal force during braking/driving of a tire by providing the tire with the time-series data of a slip ratio in a longitudinal direction of the tire as a measurement condition;

setting the value of the transient response parameter initially and defining a response function of the first-order-lag response, thereby making the tire dynamic model operable;

performing simulating calculation including;

obtaining the time-series data of a transient response of the slip ratio between the tread part and a road surface in the tire dynamic model by computing a convolution integral of the defined response function of the first-order-lag response with a time gradient of the time-series data of the slip ratio provided to the tire as the measurement condition;

calculating a longitudinal force by using the tire dynamic model based on a value of the obtained time-series data of the transient response of the slip ratio, to obtain the time-series data of the longitudinal force in a transient state during braking/driving; and

calculating a sum of square residuals of the calculated time-series data of the longitudinal force and the measurement data of the tire, repeating the simulating calculation while correcting the set value of the transient response parameter until the sum of square residuals becomes minimum, and determining the value of the transient response parameter obtained when the sum of square residuals becomes minimum as the value of the transient response parameter that defines the first-order-lag response.

13. A tire designing method, comprising the steps of:

calculating and outputting tire transient response data by using a tire transient response data calculating method for calculating the tire transient response data during cornering with a slip angle provided as time-series data based on a tire dynamic model constituted by using at least one tire dynamic element parameter,

the tire transient response data calculating method including the steps of;

acquiring a value of the tire dynamic element parameter constituting the tire dynamic model, thereby making the tire dynamic model operable;

calculating the time-series data of a transient response of the slip angle between a tread part and a road surface in the tire dynamic model by computing a convolution integral of a response function of a first-order-lag response of the tire dynamic model, which specifies a deformation response of the tread part during cornering, with a time gradient of the time-series data of the slip angle provided to the tire dynamic model; and

calculating, as transient response data during cornering, output data of at least one of a lateral force and self-aligning torque by using the tire dynamic model based on the time-series data of the transient response of the slip angle;

repeatedly calculating and outputting the tire transient response data while correcting the value of the tire dynamic element parameter or a value of a transient response parameter that defines the first-order-lag response by adjusting a tire component member that defines the tire dynamic element parameter or the first-order-lag response until the output transient response data satisfies a preset target condition; and

determining the tire component member as a target tire component member when the output data satisfies the target condition.

14. A tire designing method, comprising the steps of:

calculating and outputting tire transient response data by using a tire transient response data calculating method for calculating the tire transient response data during cornering with a slip angle provided as time-series data based on a tire dynamic model,

the tire transient response data calculating method including the steps of;

previously acquiring values of at least one of a lateral force and a self-aligning torque in a steady state from actual measurement of a tire by providing a tire with the time-series data of the slip angle varying across at least a range between 0 degrees and a predetermined angle as the slip angle in the steady state;

calculating the time-series data of a transient response of the slip angle between a tread part and a road surface in the tire dynamic model by computing a convolution integral of a response function of a first-order-lag response of the tire dynamic model, which specifies a deformation response of the tread part during cornering, with a time gradient of the time-series data of the slip angle provided to the tire; and

calculating, as transient response data during cornering, the time-series data of at least one of the lateral force and self-aligning torque in a transient state by obtaining a value of one of the lateral force and self-aligning torque in the steady state corresponding to a value of the calculated time-series data of the transient response of the slip angle;

repeatedly calculating and outputting the tire transient response data while correcting a value of a transient response parameter that defines the first-order-lag response by adjusting a tire component member that defines the first-order-lag response until the output transient response data satisfies a preset target condition; and

determining the tire component member as a target tire component member when the output data satisfies the target condition.

15. A tire designing method, comprising the steps of:

calculating and outputting tire transient response data by using a tire transient response data calculating method for calculating the tire transient response data during braking/driving with a slip ratio in a longitudinal direction of a tire provided as time-series data based on a tire dynamic model constituted by using at least one of tire dynamic element parameter,

the tire transient response data calculating method including the steps of;

acquiring a value of the tire dynamic element parameter constituting the tire dynamic model, thereby making the tire dynamic model operable;

calculating the time-series data of a transient response of the slip ratio between a tread part and a road surface in the tire dynamic model by computing a convolution integral of a response function of a first-order-lag response of the tire dynamic model, which specifies a deformation response of the tread part during braking/driving, with a time gradient of the time-series data of the slip ratio provided to the tire dynamic model; and

calculating, as transient response data during braking/driving, output data of a longitudinal force by using the tire dynamic model based on the time-series data of the transient response of the slip ratio;

repeatedly calculating and outputting the tire transient response data while correcting a value of the tire dynamic element parameter or a value of a transient response parameter that defines the first-order-lag response by adjusting a tire component member that defines one of the tire dynamic element parameter or the first-order-lag response until the output transient response data satisfies a preset target condition; and

determining the tire component member as a target tire component member when the output data satisfies the target condition.

16. A tire designing method, comprising the steps of:

calculating and outputting tire transient response data by using a tire transient response data calculating method for calculating the tire transient response data during braking/driving with a slip ratio in a longitudinal direction of a tire provided as time-series data based on a tire dynamic model,

the tire transient response data calculating method including the steps of;

previously acquiring a value of a longitudinal force in a steady state from actual measurement of the tire when the time-series data of the slip ratio varying across at least a range between 0 degrees and a predetermined slip ratio is provided as the slip ratio in the steady state;

calculating the time-series data of a transient response of the slip ratio between a tread part and a road surface in the tire dynamic model by computing a convolution integral of a response function of a first-order-lag response of the tire dynamic model, which specifies a deformation response of the tread part during braking/driving, with a time gradient of the time-series data of the slip ratio; and

acquiring, as transient response data during braking/driving, the time-series data of the longitudinal force in a transient state by obtaining a value of the longitudinal force in the steady state corresponding to a value of the calculated time-series data of the transient response of the slip ratio;

repeatedly calculating and outputting the tire transient response data while correcting a value of a transient response parameter that defines the first-order-lag response by adjusting a tire component member that defines the first-order-lag response until the output transient response data satisfies a preset target condition; and

determining the tire component member as a target tire component member when the output data satisfies the target condition.

17. A vehicle motion predicting method, comprising the steps of:

calculating and outputting tire transient response data by using a tire transient response data calculating method for calculating the tire transient response data during cornering with a slip angle provided as time-series data based on a tire dynamic model constituted by using at least one tire dynamic element parameter,

the tire transient response data calculating method including the steps of;

acquiring a value of the tire dynamic element parameter constituting the tire dynamic model, thereby making the tire dynamic model operable;

calculating the time-series data of a transient response of the slip angle between a tread part and a road surface in the tire dynamic model by computing a convolution integral of a response function of a first-order-lag response of the tire dynamic model, which specifies a deformation response of the tread part during cornering, with a time gradient of the time-series data of the slip angle provided to the tire dynamic model; and

calculating, as transient response data during cornering, output data of at least one of a lateral force and self-aligning torque by using the tire dynamic model based on the time-series data of the transient response of the slip angle; and

predicting a vehicle motion based on a vehicle model by providing the transient response data to an axle portion of the vehicle model.

18. A vehicle motion predicting method, comprising the steps of:

calculating and outputting tire transient response data by using a tire transient response data calculating method for calculating the tire transient response data during cornering with a slip angle provided as time-series data based on a tire dynamic model,

the tire transient response data calculating method including the steps of;

previously acquiring values of at least one of a lateral force and a self-aligning torque in a steady state from actual measurement of a tire by providing a tire with the time-series data of the slip angle varying across at least a range between 0 degrees and a predetermined angle as the slip angle in the steady state;

calculating the time-series data of a transient response of the slip angle between a tread part and a road surface in the tire dynamic model by computing a convolution integral of a response function of a first-order-lag response of the tire dynamic model, which specifies a deformation response of the tread part during cornering, with a time gradient of the time-series data of the slip angle provided to the tire; and

acquiring, as transient response data during cornering, the time-series data of one of the lateral force and self-aligning torque in a transient state by obtaining a value of at least one of the lateral force and self-aligning torque in the steady state corresponding to a value of the calculated time-series data of the transient response of the slip angle; and

predicting a vehicle motion based on a vehicle model by providing the transient response data to an axle portion of the vehicle model.

19. A vehicle motion predicting method, comprising the steps of:

calculating and outputting tire transient response data by using a tire transient response data calculating method for calculating the tire transient response data during braking/driving with a slip ratio in a longitudinal direction of a tire provided as time-series data based on a tire dynamic model constituted by using at least one tire dynamic element parameter,

the tire transient response data calculating method including the steps of;

acquiring a value of the tire dynamic element parameter constituting the tire dynamic model, thereby making the tire dynamic model operable;

calculating the time-series data of a transient response of the slip ratio between a tread part and a road surface in the tire dynamic model by computing a convolution integral of a response function of a first-order-lag response of the tire dynamic model, which specifies a deformation response of the tread part during braking/driving, with a time gradient of the time-series data of the slip ratio provided to the tire dynamic model; and

calculating, as transient response data during braking/driving, output data of a longitudinal force by using the tire dynamic model based on the time-series data of the transient response of the slip ratio; and

predicting a vehicle motion based on a vehicle model by providing the transient response data to an axle portion of the vehicle model.

20. A vehicle motion predicting method, comprising the steps of:

calculating and outputting tire transient response data by using a tire transient response data calculating method for calculating the tire transient response data during braking/driving with a slip ratio in a longitudinal direction of a tire provided as time-series data based on a tire dynamic model,

the tire transient response data calculating method including the steps of;

previously acquiring values of a longitudinal force in a steady state from actual measurement of the tire when the time-series data of the slip ratio varying across at least a range between 0 degrees and a predetermined slip ratio is provided as the slip ratio in the steady state;

calculating the time-series data of a transient response of the slip ratio between a tread part and a road surface in the tire dynamic model by computing a convolution integral of a response function of a first-order-lag response of the tire dynamic model, which specifies a deformation response of the tread part during braking/driving, with a time gradient of the time-series data of the slip ratio; and

acquiring, as transient response data during braking/driving, the time-series data of the longitudinal force in a transient state by obtaining a value of the longitudinal force in the steady state corresponding to a value of the calculated time-series data of the transient response of the slip ratio; and

predicting a vehicle motion based on a vehicle model by providing the transient response data to an axle portion of the vehicle model.

21. A method of evaluating a cornering characteristic of a tire when a slip angle is provided as time-series data, comprising the steps of:

acquiring time-series lateral force data with respect to the time-series data of the slip angle, regarding the tire which generates a tire lateral force by being brought into contact with a ground in a contact patch and rolling at a predetermined rolling speed; and

deriving a value of a tire dynamic element parameter representing the cornering characteristic of the tire by using;

a transient response calculation model that is constituted by using at least one tire dynamic element parameter and is used to calculate output data corresponding to the lateral force data of a transient response generated in the tire with respect to the time-series data of the slip angle; and

the acquired lateral force data,

wherein the step of deriving the value of the tire dynamic element parameter is performed by using the time-series data of a transient response of the slip angle obtained by computing a convolution integral of a response function of a first-order-lag response of the transient response calculation model, which specifies a deformation response of a tread part of the tire during cornering, with a time gradient of the time-series data of the slip angle provided to the transient response calculation model.

22. The method of evaluating a cornering characteristic of a tire according to claim 21, wherein the step of acquiring the lateral force data is performed by reproducing an evaluation target tire with a tire finite element model, which is obtained by dividing the evaluation target tire into a finite number of elements, and by using a finite element method to acquire, as the lateral force data, simulation data of the lateral force acting on the tire finite element model which is brought into contact with the ground in the contact patch and caused to roll at the predetermined rolling speed and to which a time-series slip angle is input.

23. The method of evaluating a cornering characteristic of a tire according to claim 22, wherein the tire finite element model is coupled with a rim model for reproducing a rim, and reproduces the tire brought into contact with the ground in the contact patch and rolling at the predetermined rolling speed by bringing the tire finite element model into contact with a flat virtual road surface in the contact patch and moving the tire finite element model at the predetermined rolling speed relatively to the virtual road surface.

24. The method of evaluating a cornering characteristic of a tire according to claim 22, wherein the tire finite element model includes a reinforcement material portion corresponding to a cord reinforcing material of the tire, the reinforcement material portion having such a material characteristic that a stiffness along a tensile direction and a stiffness along a compression direction are different from each other.

25. The method of evaluating a cornering characteristic of a tire according to claim 22, wherein the tire finite element model is subjected to an inflation process for simulating tire inflation, and the inflation process is performed after one of an initial stress and an initial strain is applied to at least one portion of the tire finite element model.

26. The method of evaluating a cornering characteristic of a tire according to claim 21, wherein the step of acquiring the lateral force data is performed by providing a time-series slip angle to the tire while bringing the tire into contact with the ground in the contact patch and rolling the tire at the predetermined rolling speed, and by acquiring, as the lateral force data, measurement data of the time-series tire lateral force corresponding to the slip angle.

27. The method of evaluating a cornering characteristic of a tire according to claim 21, wherein:

the transient response calculation model is represented by setting a transient response of the tire lateral force with respect to the slip angle as a first-order-lag response; and

the slip angle to be input ranges within such a linear range that the slip angle and the response of the tire lateral force with respect to the slip angle are in a substantially linear relation.

28. The method of evaluating a cornering characteristic of a tire according to claim 21, wherein the step of deriving the value of the tire dynamic element parameter is performed by using the time-series data of the input slip angle and the time-series lateral force data corresponding to the time-series data of the slip angle in such a manner that the output data of the transient response calculation model matches the time-series lateral force data within an allowable range.

29. The method of evaluating a cornering characteristic of a tire according to claim 21, wherein the slip angle ranges from −

2.0 degrees to 2.0 degrees.

30. The method of evaluating a cornering characteristic of a tire according to claim 29, wherein:

when the output data is represented by F(t), the transient response calculation model contains a formula represented by Formula (A) described bellow; and

the step of deriving the value of the tire dynamic element parameter includes obtaining a value of a cornering stiffness K_y and a value of a time constant t₃, which are dynamic element parameters of Formula (A) described bellow, by using the input time-series slip angle α

(t) in such a manner that the F(t) within Formula (A) described bellow matches the time-series lateral force data F_y(t) corresponding to the slip angle α

(t) within the allowable range.

31. The method of evaluating a cornering characteristic of a tire according to claim 30, wherein:

the output data calculated by the transient response calculation model comprises data of the tire lateral force transmitting to a wheel side via an equivalent stiffness K_L of an entirety of the tire with respect to an input of the slip angle; and

when the predetermined rolling speed at a time of acquiring the lateral force data is assumed to be V, the step of deriving the value of the tire dynamic element parameter includes deriving a value of the equivalent stiffness K_L representing a transmission characteristic of the tire lateral force by substituting the value of the cornering stiffness K_y and the value of the time constant t₃, which are obtained by using the above-mentioned Formula (A), and the rolling speed V, into Formula (B) described bellow.

32. An apparatus for evaluating a cornering characteristic of a tire under a condition in which a slip angle is provided as time-series data, comprising:

a data acquiring section for acquiring time-series lateral force data with respect to a time-series slip angle, regarding the tire being brought into contact with a ground in a contact patch and rolling at a predetermined rolling speed; and

a deriving section for deriving a value of a tire dynamic element parameter representing the cornering characteristic of the tire by using;

a transient response calculation model that is constituted by using at least one tire dynamic element parameter and is used to calculate output data corresponding to the lateral force data of a transient response generated in the tire with respect to the slip angle; and

the lateral force data,

wherein the deriving section derives the value of the tire dynamic element parameter by using the time-series data of a transient response of the slip angle obtained by computing a convolution integral of a response function of a first-order-lag response, which specifies a deformation response of a tread part of the tire during cornering, with a time gradient of the time-series data of the slip angle provided to the transient response calculation model.