JP4160099B1 - Tire model determination method, tire transient response data calculation method, tire design method, and tire evaluation method - Google Patents

Abstract

A tire model that reproduces the transient response of the tire is determined from measurement data of the transient response of the longitudinal force of the tire, and the transient response data is calculated from a desired slip ratio using the model.
A time constant of a first-order lag model of a tire is initially set, and a response function of a first-order lag response is determined. The effective slip ratio is obtained by performing convolution integration between the determined first-order delay response function and the time variation of the time-series data of the set slip ratio. A characteristic curve representing the measured longitudinal force value with respect to the effective slip ratio value is subjected to least-squares regression to one smooth curve using a curve function. A square residual sum of the least square regression curve at this time and the actually measured characteristic curve is obtained, and the time constant is corrected so that the square residual sum is minimized. The time constant when the residual sum of squares is minimized is determined as the time constant of the first-order lag response, and the tire model is determined. A longitudinal force with respect to a desired set slip ratio is calculated using the tire Dell and the time constant.
[Selection] Figure 3

Description

  The present invention determines a first-order lag model that reproduces the transient response of the longitudinal force of the tire from the measurement data of the transient response of the longitudinal force of the tire obtained by giving the tire an increase / decrease in the slip ratio in the longitudinal direction of the tire. Model determination method, tire transient response data calculation method for calculating a longitudinal response transient response caused by giving a desired change in slip ratio to a rolling tire, tire evaluation method using these methods, and The present invention relates to a tire design method.

  Currently, in the automobile industry, advanced vehicle control for safe driving of vehicles and avoidance of danger is required. Since the tire is interposed between the vehicle and the road surface and transmits the force from the road surface to the vehicle only, the role of the tire is important. Therefore, it is necessary to analyze the braking / driving characteristics of the tire.

  Patent Document 1 below discloses calculating cornering characteristics of a steady-state tire when a slip angle is given as time series data based on a tire dynamic model configured using a plurality of tire dynamic element parameters. Has been. Thereby, it is supposed that it becomes possible to design a tire efficiently.

  However, in the above tire dynamic model, even if a slip angle can be given to obtain a cornering characteristic in a steady state, a slip ratio in the tire longitudinal direction is given, and a transient response of the longitudinal force that changes momentarily with time change is given. Cannot be reproduced.

  Further, in today's vehicles, braking using an anti-lock braking system (ABS) is normally performed. In ABS, the slip ratio is controlled at several Hz so that the braking force during braking is always maximized. For this reason, the generated braking force is based on characteristics of a transient state different from the steady state. This characteristic is different from the characteristic when the braking force is applied in a steady state. Therefore, even if the longitudinal force in the steady state can be calculated using the tire dynamic model instead of the lateral force, the vehicle characteristics including the ABS cannot be evaluated using the longitudinal force.

JP 2005-88832 A

  Therefore, in order to solve the above-described conventional problems, the present invention is based on the measurement data of the transient response of the longitudinal force of the tire obtained by giving the tire an increase / decrease in the slip ratio in the longitudinal direction of the tire. Provided is a tire model determination method capable of determining a first-order lag model that reproduces a transient response, and calculates a tire transient response when a desired slip ratio is given using the determined tire dynamic model. An object of the present invention is to provide a method for calculating tire transient response data. Furthermore, a tire evaluation method and a tire design method using these methods are provided.

  The present invention determines a first-order lag model that reproduces the transient response of the longitudinal force of the tire from the measurement data of the transient response of the longitudinal force of the tire obtained by giving the tire an increase / decrease in the slip ratio in the longitudinal direction of the tire. A method for determining a model, comprising: initializing a time constant of the first-order lag model to determine a response function of a first-order lag response in the first-order lag model; and the determined first-order lag response function; Effective slip ratio data obtained by performing convolution integration with the time change amount of the time series data of the slip ratio given to the tire is obtained as time series data of the transient response of the slip ratio, and the effective slip ratio data The characteristic curve representing the value of the longitudinal force with respect to the value is subjected to least squares regression on a smooth curve using a curve function, and the least squares obtained by least squares regression are performed. A step of performing a regression calculation to obtain a square residual sum of a regression curve and a characteristic curve, and repeat the regression calculation by correcting the set time constant until the calculated square residual sum is equal to or less than a predetermined value. And determining the first-order lag model by determining the time constant when the sum of squared residuals is equal to or less than a predetermined value as a time constant for determining the first-order lag response. A method for determining a characteristic tire model is provided.

  In this case, the slip ratio is given so as to generate a braking force as a longitudinal force of the tire, and the time constant of the first-order model is a function that changes according to the slip ratio, and the slip ratio is zero. The time constant indicates a first value, and as the slip ratio increases from the first value, the time constant monotonously changes to become a second value. Thereafter, the time constant becomes the second value. In the step of determining the response function of the first-order lag response, the first value and the second value that define the time constant are set in the step of determining the response function of the first-order lag response. In the step of setting a time constant of a first-order lag model to determine a response function of a first-order lag response in the first-order lag model, and determining the first-order lag model, the square residual sum is reduced to the predetermined value or less. , Set the first The regression calculation is repeated by correcting at least one parameter value of the value and the second value, and the first value and the second value when the sum of squared residuals is equal to or less than the predetermined value. Preferably, the first-order lag model is determined by determining a value as a value that defines a time constant that defines the first-order lag response.

  Furthermore, the present invention is a tire transient response data calculating method for calculating a transient response of the longitudinal force generated by giving a desired change in slip ratio to the rolling tire in the longitudinal direction of the tire. Defining a response function of the first-order lag model determined by a determination method, obtaining the least square regression curve when the first-order lag model is determined, and a response function of the first-order lag Effective slip ratio data obtained by performing convolution integration with the time variation of the time series data of the desired slip ratio is obtained as time series data of the transient response of the slip ratio, and the least squares with respect to the effective slip ratio data are obtained. Calculating a value of a regression curve as a value of transient response data of longitudinal force with respect to a change in the desired slip ratio. It provides a method for calculating the tire transient response data, characterized in that.

The present invention also relates to a tire design method, the step of acquiring the parameter value determined by the tire model determination method according to claim 2 for a reference prototype tire, and the parameter value Using the evaluation of the prototype tire, and designing the tire by adjusting the constituent members of the prototype tire based on the evaluation result of the prototype tire. I will provide a.
Further, the present invention is a tire evaluation method, the step of obtaining the transient response data obtained by the tire model transient response data calculation method, the step of evaluating the tire using the transient response data, A method for evaluating a tire is provided.
In that case, it is preferable to evaluate the tire by predicting the behavior of the vehicle by giving the transient response data to the vehicle model.

In the present invention, effective slip ratio data obtained by performing convolution integration of the response function of the first-order lag and the time variation of the time series data of the slip ratio is obtained, and the value of the longitudinal force with respect to the value of this effective slip ratio data A regression calculation is performed to obtain a sum of square residuals of the regression curve obtained by least square regression and the characteristic curve. For this reason, a first-order lag model that reproduces the transient response of the longitudinal force of the tire can be determined by obtaining a value of a time constant such that the sum of squared residuals is a predetermined value or less. In particular, the actual behavior of the braking / driving characteristics can be reproduced by changing the time constant of the response function of the first-order lag model according to the slip ratio.
In addition, by using the least squares regression curve obtained when determining the first order lag model together with the first order lag model, the front-rear force of the tire with respect to a desired slip ratio arbitrarily set by an operator or the like is obtained. Transient response can be reproduced.

  Hereinafter, a tire model determination method, tire transient response data calculation method, tire evaluation method, and tire design method of the present invention will be described in detail based on embodiments shown in the accompanying drawings.

FIG. 1 is a block diagram of a computing device 10 that implements a tire model determination method, tire transient response data calculation method, tire evaluation method, and tire design method according to the present invention.
The arithmetic unit 10 determines an optimal first-order lag model that reproduces the transient response of the longitudinal force generated by applying a slip ratio in the tire longitudinal direction to the rolling tire, and uses this first-order lag model to determine the slip Calculate time-series data of the transient response of the longitudinal force when a desired slip ratio is given to a tire that rolls at a constant rate, and the time constant and calculated time-series data used for this first-order lag model This is a device for evaluating the characteristics of tires and vehicles using The front-rear direction of the tire in the present invention refers to a direction that is orthogonal to the tire rotation axis of a tire that rolls at a slip angle of 0 degrees on a horizontal plane where the tire contacts and is parallel to the horizontal plane.

The arithmetic device 10 is configured by a computer and includes a CPU 12, a memory 14, and an I / O interface unit 16. The arithmetic device 10 further reads out and activates the software stored in the memory 14, thereby substituting the data input unit 20, the first-order lag model determining unit 30, the transient response data calculating unit 40, and the tire / vehicle characteristic evaluating unit 50. It is a device that forms as a program. The arithmetic device 10 is connected to a display 17, a printer 18, and an input operation system 19 such as a mouse or a keyboard.
The CPU 12 is a calculation unit that substantially calculates each part, and the memory 14 stores and saves data and processing results calculated in each part in addition to software for forming each part. The I / O interface unit 16 is a part that outputs data and processing results calculated in each part to a display 17 and a printer 18 that are external devices.
The computing device 10 is connected to a tire testing device 60 that measures the lateral force by actually rolling the tire.

  The data input unit 20 fixes the slip angle and the load to predetermined values, gives time series data of the slip ratio in the tire front-rear direction (hereinafter referred to as slip ratio S (t)) to the tire as a measurement condition, and gives the tire This is a part that acquires measurement data of the transient response of the longitudinal force, and receives and acquires predetermined information as required. These pieces of information are stored and saved in the memory 14. Data input to the data input unit 20 is input through the I / O interface unit 16.

The first-order lag model determination unit 30 determines the time constant in the first-order lag model using the measurement data of the transient response of the longitudinal force (hereinafter referred to as F _x (t)), and represents the first-order lag model. This is the part that determines the tire model. Here, the time constant in the first-order lag model is set so as to change according to the value of the slip ratio S (t). The first-order lag model determining unit 30, as shown in equation (1) described later, a response function of a first-order lag model having a time constant t _ms and a set slip ratio (hereinafter referred to as a set slip ratio) S ( The effective slip ratio S ′ (t) is obtained by performing convolution integration with the time variation (time gradient) of t), and the function Z (S) is used as the time constant t _ms used at this time. Here, the function Z (S) depends on the set slip ratio S (t) given to the tire, and is a function that changes according to the set slip ratio S (t) as shown in FIG. constant t _ms time when setting the slip rate is 0 represents the maximum value t _s, the minimum value t _d next to monotonously decreases the time constant t _ms in accordance with the maximum value t _s from the setting slip ratio S increases, this Thereafter, the time constant t _ms is a function for maintaining the minimum value t _d . More specifically, the time constant t _ms has a value between the maximum value t _s and the minimum value t _d, a maximum value t _s at setting slip ratio S (t) = 0, set slip ratio S As (t) increases, it decreases linearly to a minimum value t _d , and thereafter the time constant t _ms is a function that maintains the minimum value t _d even if the set slip ratio S (t) increases. The value of the set slip ratio S ₁ when the set slip ratio S (t) is increased and the minimum value t _d is first taken is twice the slip ratio when the actual tire has a maximum peak of longitudinal force. This is a value of about 0.3 to 0.5. In the present invention, the value between the maximum value t _s and the minimum value t _d of Z (S) decreases linearly and monotonously as the set slip ratio S (t) increases, and decreases monotonically in a curve. May be.
In the actual tire contact surface, in the vicinity of the slip ratio S = 0, the longitudinal force is generated only by the adhesion friction force, and as the slip ratio S increases, this adhesion friction force decreases and instead the slip friction force increases. . When the slip ratio S increases and the slip ratio S = S ₁ , the adhesion friction becomes substantially 0, and the sliding friction force becomes dominant.
Therefore, in the present invention, the time constant t _ms at the set slip ratio S (t) = 0 in which the adhesion friction force is substantially dominant is the time constant t determined by the adhesion friction between the tire tread member and the contact surface. _{Use s} . On the other hand, the time constant t _ms at the slip ratio after the slip ratio S ₁ where the sliding friction friction force is substantially dominant is the time constant t _d determined by the sliding friction between the tread member of the tire and the ground contact surface. Note that in the range between the set slip ratio S (t) = 0 and S1, adhesion friction and slip friction are mixed, and when the set slip ratio S (t) is small, the contribution of the adhesion friction is large. When the slip ratio S (t) is large, the contribution of sliding friction is large. From this, the time constant t _ms is linearly and monotonously changed (increased or decreased) between the time constants t _s and t _d . The time constant t _s determined by the adhesion friction between the tire tread member and the contact surface is larger than the time constant t _d as will be described later. Therefore, the time constant t _s is the maximum value, and the time constant t _d Is the minimum value.
That is, Z (S) is used as the time constant t _ms of the response function of the first-order lag, as shown in Equation (1) described later.
By using such a response function and longitudinal force measurement data, the time constant t _s and t _d of Z (S), which is the time constant t _ms , is determined to determine the first-order lag model. Details will be described later.

The transient response data calculation unit 40 acquires the response function of the first-order lag model determined by the first-order lag model determination unit 30 and calculates the least-square regression curve calculated when determining the response function of the first-order lag model R _ms (S ′ (t)) is obtained, and using this response function and the least square regression curve R _ms (S ′ (t)), a desired set slip ratio S (t ) To calculate the friction coefficient μ (t) which is time series data of the transient response.

The tire / vehicle characteristic evaluation unit 50 inputs the friction coefficient μ (t) calculated by the transient response data calculation unit 40 to a vehicle model (not shown), calculates the braking distance of the vehicle, and evaluates the tire. It is a part to do.
The processing contents of these parts will be described in detail in the data processing method of the arithmetic unit 10 described later.

FIG. 3 is a flowchart showing an example of a flow of the tire model determination method of the present invention executed in the first-order lag model determination unit 30 of the arithmetic device 10.
First, in the data input unit 20, the set slip ratio S (t) is input and set via the input operation system 19 (step S10). The slip ratio S (t) is given so as to generate a braking force as a longitudinal force of the tire. The set slip ratio S (t) is stored in the memory 14, and information on measurement conditions such as the rolling speed V and the load is input via the input operation system 19 and stored in the memory 14. In the present invention, the slip ratio S (t) may be given so as to generate a driving force as a front-rear force of the tire, but in the following description, a case where a braking force is generated will be described. .
Each information including the set slip ratio S (t) is sent to the tire testing device 60. In the tire testing apparatus 60, based on each sent information, the actual tire is brought into a rolling state at a slip angle of 0 degree with a set load, and the transient response of the longitudinal force is measured at the set slip ratio S (t). Thus, F _x (t) which is time series data of the transient response of the longitudinal force is obtained (step S20). F _x (t) is stored in the memory 14 via the I / O interface unit 16 and read out to the first-order lag model determining unit 30.

On the other hand, the first-order lag model determining unit 30 sets time constants t _s and t _{d in the} following equation (1) (step S30). The value of the time constant to be set may be a default value set in advance or may be a value input and set by the input operation system 19 by the operator. Thereby, the response function of the first-order lag model is determined.

Next, the effective slip ratio S ′ (t) is calculated according to the following expression (2) (step S40).
Specifically, the effective slip ratio S ′ (t) is obtained as time series data of the transient response by performing a convolution integration between the response function of the determined first-order lag model and the time variation of the set slip ratio S (t). Desired. At this time, the time constant t _ms in the equation (2) is Z (S) defined by the equation (1), and S in the right side of the equation (1) at this time is the set slip ratio S (T) is used.

Thus, the effective slip ratio S ′ (t) is calculated because it takes time to stabilize the tire in a steady state even if the set slip ratio S (t) of the tire changes instantaneously. friction coefficient obtained by dividing the longitudinal force or longitudinal force at constant load to the generator mu (t) is also set slip ratio S (t) and equilibrium with became F _x (t) or the coefficient of friction mu (t) This is because it takes time until it is generated. For this reason, in the present invention, the effective slip ratio S ′ (t) where F _x (t) or the friction coefficient μ (t) is assumed to be balanced is determined using the response function of the first-order lag model.

Next, a spline function is applied to the characteristic curve representing the effective slip ratio S ′ (t) dependence of the friction coefficient μ (t) obtained by dividing F _x (t) measured in step S20 by a constant load F _z. A smooth curve function is used to regress, and a square residual sum between the regressed curve function and the characteristic curve is calculated (step S50). For example, a B-spline function is preferably used as the spline function. Since the friction coefficient μ (t) is obtained by dividing F _x (t) by a constant load F _z , the time series data Fx (S ′) of the longitudinal force with respect to the value of the effective slip ratio data S ′ (t). It corresponds to a characteristic curve representing the value of (t)).
The regression will be described in detail. When the B-spline function is represented by B ₁ (x), B ₂ (x), B ₃ (x),..., The one curve function is f (x). Then, f (x) is represented by a linear linear combination such as B ₁ (x), B ₂ (x), B ₃ (x), as shown by the following formula (3).

Here, when the value of the one curve function obtained by regression vibrates with respect to the slip ratio S ′ (t), the difference between the values of the coefficients α _i and α _{i + 1 in} the equation (3) is also extreme. In order to prevent such vibration from occurring, the difference between the values of the coefficients α _i and α _{i + 1} fluctuates when returning to a smooth curve function using the spline function. In order to avoid this, a constraint condition is provided in which the adjacent difference square sum A shown in the following equation (4) holds a constant value.

Next, it is determined whether or not the calculated sum of squared residuals is equal to or less than a predetermined value (step S60). If the calculated sum of squared residuals is larger than a predetermined value, the set time constants t _s and t _d are corrected to correct the response function of the first-order lag model (step S80), and steps S50 and 60 are repeated. Done. For example, a Newton-Raphson method is used to correct the values of the time constants t _s and t _d . In step S60, the determination is made based on whether or not the squared residual sum is equal to or smaller than a predetermined value, but the determination may be made based on whether or not the squared residual sum is a minimum value.

Finally, the values of the time constants t _s and t _d when the sum of squared residuals is equal to or less than a predetermined value are determined as parameter values that define the first-order lag response model (step S70). Further, a least square regression curve when the sum of squared residuals becomes a predetermined value or less is determined as R _ms (S ′ (t)) in the following equation (3). The values of the time constants t _s and t _d and the least square regression curve R _ms (S ′ (t)) are stored in the memory 14.
Since the effective slip ratio S ′ (t) uses the first-order lag model as described above, the effective slip ratio when the set slip ratio S (t) is a constant value (steady state). S ′ (t) coincides with the set slip ratio S (t). Therefore, the least square regression curve R _ms (S ′ (t)) represents a characteristic curve indicating the load dependence of the longitudinal force in the steady state.

In the present embodiment, the time constant t _s, was used t _d as a parameter of any first-order lag response function, in the present invention, determining the value of the constant t _s when at least the time constant t _s as a parameter Good. The value of the time constant t _d does not change greatly depending on the material of the tire tread portion, etc., and has a substantially constant value, which is extremely small compared to the value of the time constant t _s. The contribution to '(t) is small. The value of the time constant td is the default setting, for example, is set to t _d = .006 to .008 seconds. Of course, the time constant td may be set by an input by an operator.

FIG. 4 shows the value (measured data) of the friction coefficient μ (t) obtained by dividing the time series data F _x (t) of the longitudinal force during the transient response acting on the actual tire by the load, The graph when the set slip ratio S (t) is taken on the horizontal axis is shown. The tire size is 205 / 55R16 89V, the load is 6KN, the rolling speed V = 64 km / hour, and the road surface is a wet road surface condition. The horizontal axis is log-displayed so that the behavior near t = 0 can be easily seen.
On the other hand, in FIG. 5 (a) ~ (c) , the time constant t _d is fixed to 0.0074 seconds, when upon correct only constant _{t s} as a parameter, the time constant _{t s} and the residual It is a figure which shows a relationship. 5 (a) is, when the time constant t _s value is smaller than the optimum value and the regression and curve of (t s ₌ 0.001 seconds), the distribution of the residual of the data of the measured curve at that time preparative, FIG. 5 (b), when the time constant t _s is the optimum value and the regression and curve of (t _s = 0.0675 seconds), and a distribution of the residual of the data of the measured curve at that time , FIG. 5 (c) when it becomes greater than the optimum value (t _s) is when the regressed curve of (t _s = 0.3 sec), and a distribution of the residual of the data of the measured curve at that time , Respectively.
Figure 6 is a sum of squared residuals against time (t _s) is a diagram showing how the changes. When the minimum value by a constant t _s = 0.0575 s, the time constant t _s = 0.0575 seconds is seen to be optimum value.

FIG. 7 shows the least square regression curve R _ms (S ′ (t)) at a time constant t _s = 0.0575 seconds and t _d = 0.0074 seconds. In the present invention, a tire transient response data calculation method to be described later is performed using the time constants t _s = 0.0575 seconds, t _d = 0.0074 seconds, and the least square regression curve R _ms (S ′ (t)). .

FIGS. 8A to 8D are diagrams using time series data of longitudinal force in a transient response state when a tire having a tire size of 195 / 65R15 is driven on a wet road surface with a load of 6 kN and a rolling speed of 64 km / hour. These are various data when the processing shown in FIG.
FIG. 8A shows the set input slip ratio S (t) and the effective slip ratio S ′ (t) at the optimum time constant values (time constant t _s = 0.0447 seconds, t _d = 0.0060 seconds). ). FIG. 8B shows a friction coefficient μ (measured data) obtained by dividing the longitudinal force F _x (t) at this time by a constant load F _z (= 6 kN). FIG. 8C shows the friction coefficient μ (S (t)) at the time constant t _s = 0.0447 seconds and t _d = 0.0060 seconds when the set slip ratio S (t) is taken on the horizontal axis. Show. FIG. 8D shows the least square regression curve R _ms (S ′ (t)) at the optimal time constant t _s = 0.0447 seconds and t _d = 0.0060 seconds that minimizes the residual sum of squares. ing.
In the present invention, a tire transient response data calculation method, which will be described later, using this time constant t _s = 0.0447 seconds, t _d = 0.0060 seconds, and the least square regression curve R _ms (S ′ (t)). Is done.

FIG. 9 is a flowchart showing a flow of one embodiment of the tire transient response data calculation method of the present invention. In the tire transient response data calculation method, the friction coefficient μ (t) is calculated by sequentially calculating the friction coefficient under the condition of the constant load F _z while ticking the time step with the constant time width Δt.

First, a desired set slip rate S (t) is input and set by the operator using the input operation system 19 (step S100). The input set slip ratio S (t) is stored in the memory 14.
Next, in the transient response data calculation unit 40, the time constants t _s and t _d for determining the time constant t _ms of the first-order lag model stored in the memory 14 and the least square regression curve R _ms (S ′ (t)) Are read and acquired.
Next, the effective slip ratio S ′ (t) is calculated using the above equation (2) (step S120).
At this time, the time constant t _ms used for calculating the effective slip ratio S ′ (t) is changed to the effective time at the previous time step instead of the set slip ratio S (t) shown in the above equation (1). A slip ratio S ′ (t−Δt) is used. The effective slip rate S ′ (t−Δt) is used instead of the set slip rate S (t) because the effective slip rate S ′ (t−Δt) is in a transient state compared to the set slip rate S (t). This is because the ratio between the adhesion friction force and the sliding friction force in the ground plane is reproduced.

Next, μ (t) is calculated by applying the least square regression curve R _ms (S ′ (t)) to the calculated effective slip ratio S ′ (t) (step S130). Since the least square regression curve R _ms (S ′ (t)) is expressed as a function in the calculation of μ (t), the value of the effective slip rate S ′ (t) is calculated as the least square regression curve R _ms (S ′ By substituting into (t)), μ (t) can be easily calculated. The calculated μ (t) is stored in the memory 14 together with the set slip ratio S (t) and the effective slip ratio S ′ (t).
The tire transient response data thus calculated μ (t) is used for evaluation of tire / vehicle characteristics.

The tire / vehicle characteristic evaluation unit 50 reads μ (t), the set slip rate S (t), and the effective slip rate S ′ (t) stored in the memory 14 and gives μ (t) to the vehicle model. The tire / vehicle characteristics are then evaluated (step S140).
For example, a vehicle deceleration simulation is performed using a vehicle model. In the present invention, the vehicle model may be an analysis model for calculating a temporal change in the moving speed when the friction coefficient μ (t) is applied to an object moving at a constant speed. For example, a four-wheel vehicle model created by ADAMS (manufactured by SMC), Carsim (manufactured by Virtual Mechanics Co., Ltd.) or veDYNA (manufactured by Neorium Technology Co., Ltd.). By fixing the vehicle model and applying μ (t) for a plurality of tires to the vehicle model and evaluating the tire / vehicle characteristics, a relative evaluation can be made between the plurality of tires.
The calculated data is stored in the memory 14 and is output to the display 17 and the printer 18.

FIGS. 10A to 10E are diagrams showing examples of each data obtained by the flow shown in FIG.
FIG. 10A shows an example of the desired set slip ratio S (t) set in step S100. The set slip ratio S (t) is actual measurement data of a slip ratio during braking applied to tires by an ABS (anti-lock brake system) of an actual vehicle. FIG. 10B shows the effective slip ratio S ′ (t) calculated in step S110 with respect to the set slip ratio S (t). An example of the effective slip ratio S ′ (t) when the time constant t _d = 0.0074 seconds and the time constant t _s = 0.01 seconds and 0.1 seconds are determined is shown. ing. When the time constant t _s = 0.10 seconds, the behavior of the effective slip ratio S ′ (r) is smooth with respect to the time constant t _s = 0.01 seconds.

On the other hand, FIG. 10C shows the result of calculating the friction coefficient μ (t) using a least square regression curve R _ms (S ′ (t)) not shown. FIG. 10D shows the behavior of the friction coefficient μ (S (t)) when the set slip ratio S (t) is taken on the horizontal axis.
The result of the vehicle deceleration simulation that reproduces the vehicle traveling speed when the set slip ratio S (t) is given to the vehicle at the traveling speed of 100 km / hour, using the friction coefficient μ (t) shown in FIG. Is shown in FIG. In FIG. 10E, the travel speed of the vehicle is on the vertical axis, and the time is on the horizontal axis. According to this, it can be seen that when the time constant t _s = 0.01 seconds, the vehicle traveling speed is decelerated faster than when the time constant t _s = 0.1 seconds. In this case, it can be evaluated that the braking characteristics of the tire are better when t _s = 0.01 seconds than when t _s = 0.10 seconds.

Furthermore, in the present invention, when designing a tire, the above-described evaluation of the tire / vehicle characteristics is performed on the reference prototype tire, and based on the evaluation result, by adjusting the constituent members of the prototype tire, It is possible to design an improved tire from the reference prototype tire.
For example, when the time constant t _s is 0.10 seconds in the reference prototype tire, the prototype tire is changed by switching to the tire tread member so that the time constant t _s = 0.01 seconds. The time constant t _s, if the road surface of the ground plane is the same, since the determined outline of a rubber characteristics of the tire tread member, by switching the tire tread elements, it is possible to adjust the time constant t _s.

  As described above, the tire model determination method, tire transient response data calculation method, tire evaluation method, and tire design method of the present invention have been described in detail, but the present invention is not limited to the above-described embodiment, and the gist of the present invention. It goes without saying that various improvements and changes may be made without departing from the scope of the invention.

It is a block diagram of the arithmetic unit which implements the tire model determination method, tire transient response data calculation method, and tire evaluation method of the present invention. It is a figure explaining the time constant used with the arithmetic unit shown in FIG. It is a flowchart which shows an example of the flow of the determination method of the tire model of this invention. It is a figure which shows an example of the data obtained by the determination method of the tire model shown in FIG. (A)-(c) is a figure which shows the other example of the various data obtained by the determination method of the tire model shown in FIG. It is a figure which shows the other example of the data obtained by the determination method of the tire model shown in FIG. It is a figure which shows the example of the least square regression curve obtained with the determination method of the tire model shown in FIG. (A)-(d) is a figure which shows the example of each data obtained by the flow shown in FIG. It is a flowchart which shows the flow of one Embodiment of the calculation method of the tire transient response data of this invention. (A)-(e) is a figure which shows the example of the data obtained by the evaluation method of the tire of this invention.

Explanation of symbols

10 arithmetic unit 12 CPU
DESCRIPTION OF SYMBOLS 14 Memory 16 I / O interface part 17 Display 18 Printer 19 Input operation system 20 Data input part 30 First order lag model determination part 40 Transient response data calculation part 50 Tire and vehicle characteristic evaluation part

Claims (6)

Tire model determination method for determining a first-order lag model that reproduces the transient response of the longitudinal force of the tire from measurement data of the transient response of the longitudinal force of the tire obtained by giving the tire an increase / decrease in the slip ratio in the longitudinal direction of the tire Because
Initializing a time constant of the first-order lag model to determine a response function of a first-order lag response in the first-order lag model;
The effective slip ratio data obtained by performing convolution integration between the determined first-order lag response function and the time change amount of the time series data of the slip ratio applied to the tire is obtained as a time series of the transient response of the slip ratio. The characteristic curve representing the value of the longitudinal force with respect to the value of the effective slip ratio data is obtained as data, and a least square regression is performed by performing a least square regression on a smooth curve using a curve function. Performing a regression calculation to obtain a squared residual sum of the curve and the characteristic curve;
Until the calculated residual sum of squares becomes a predetermined value or less, the set time constant is corrected and the regression calculation is repeated, and the time constant when the squared residual sum becomes a predetermined value or less is Determining a first-order lag model by determining the first-order lag response as a time constant for determining the first-order lag response. The slip ratio is given so as to generate a braking force as a longitudinal force of the tire,
The time constant of the first-order model is a function that changes according to the slip ratio, and when the slip ratio is 0, the time constant indicates a first value, and the slip ratio is calculated from the first value. As the time constant increases, the time constant monotonously changes to a second value, and thereafter, the time constant is defined by a function that maintains the second value,
In the step of determining the response function of the first-order lag response, the time constant of the first-order lag model is set by setting the first value and the second value that define the time constant. Define the response function of the first-order lag response in the second-order lag model,
In the step of determining the first-order lag model, the parameter value of at least one of the set first value and the second value is corrected until the sum of squared residuals is equal to or less than the predetermined value, and the regression is performed. The calculation is repeated, and the values of the first value and the second value when the sum of squared residuals is less than or equal to the predetermined value are determined as values that define a time constant that defines the first-order lag response. The tire model determination method according to claim 1, wherein the first-order lag model is determined. A method of calculating tire transient response data for calculating a transient response of a longitudinal force generated by giving a desired slip ratio change in a tire longitudinal direction to a rolling tire,
The response function of the first-order lag model determined by the tire model determination method according to claim 1 or 2 is defined, and the least-square regression curve when the first-order lag model is determined is acquired. Steps,
Effective slip ratio data obtained by performing convolution integration of the response function of the first-order delay and the time change amount of the time series data of the desired slip ratio is obtained as time series data of the transient response of the slip ratio, Calculating the value of the least square regression curve for the effective slip ratio data as the value of the transient response data of the longitudinal force with respect to the desired change in the slip ratio, and a method for calculating tire transient response data, comprising: . A tire design method comprising:
Obtaining the parameter value determined by the tire model determination method according to claim 2 for a reference prototype tire;
Evaluating the prototype tire using the parameter values;
And a step of designing the tire by adjusting the constituent members of the prototype tire based on the evaluation result of the prototype tire. A tire evaluation method,
Obtaining the transient response data obtained by the tire model transient response data calculation method according to claim 3;
And a step of evaluating the tire using the transient response data.   The tire evaluation method according to claim 5, wherein the tire is evaluated by predicting a behavior of the vehicle by giving the transient response data to a vehicle model.

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