JP3191708B2 - Vehicle skid state quantity detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately estimate the quantity of a lateral slipping state of a vehicle in a linear range close to a non-linear range or in a non-linear range. SOLUTION: This device 12 possesses an observer block 34 based on a vehicle model, which estimates the slip angle βh and yaw rate γh of a body by estimating the lateral forces Fyf and Fyr of front and rear wheels based on the quantity of a state including an actual yaw rate γ, and feeds back the aforesaid yaw rate, and operates at least the slip angle βh of the body as the quantity of a lateral slipping state. In this place, a feed-back gain Kb for estimating the yaw rate of the body and a feed-back gain Kg for estimating the yaw rate of the body are changed by a gain changing block 36 in response to the degree Sa of saturation of wheel lateral force, which is operated based on deviations between the reference yaw rate γt based on the quantity of a vehicle state and an actual yaw rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the amount of skidding by estimating the slip state of a vehicle such as an automobile, and more particularly to detecting the amount of skidding by estimating the slip angle of a vehicle body as the amount of skidding. Related to the device.

[0002]

2. Description of the Related Art For example, as disclosed in Japanese Patent Application Laid-Open No. 62-83247, in a device for detecting a motion state quantity such as a slip angle of a vehicle body when turning a vehicle such as an automobile, a steering angle and The front and rear wheels of the vehicle model are compared by comparing the sideslip angle of the vehicle (slip angle of the vehicle body) estimated from the vehicle model with the vehicle speed as an input variable and the lateral acceleration, yaw rate, and the sideslip angle calculated based on the vehicle speed. A technique for correcting the cornering power of the above has been conventionally known.

According to this technique, since both the steady-state motion characteristics and the transient motion characteristics of the vehicle model are corrected so as to match the characteristics of the actual vehicle, the cornering power of the front and rear wheels of the vehicle model is corrected. It is possible to improve the accuracy of estimating the motion state amount when the vehicle turns, as compared with the case where there is no vehicle.

[0004]

Generally, when the slip angle of a vehicle body is estimated from a vehicle model, the estimation accuracy is good in a linear region (linear region of tire lateral force), but in a non-linear region. In the near linear region or nonlinear region, the estimation accuracy deteriorates, and therefore, the estimation value from the vehicle model is used as it is in order to determine the behavior limit of the vehicle such as the turning limit of the vehicle and to control the turning behavior such as spin. Can not. Therefore, in determining the behavior limit of the vehicle, it is conceivable to determine the slip angle of the vehicle body by an integral operation using the lateral acceleration, the yaw rate, and the like as parameters. In this case, errors (drift) are likely to be accumulated by the integral operation, There is also a problem that the estimation accuracy of the slip angle is likely to be deteriorated due to the fact that the cant on the road surface is not estimated with high accuracy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the conventional skid state amount detecting device, and a main object of the present invention is to provide a linear region close to a nonlinear region and a nonlinear region. This is also to accurately estimate the amount of side slip state of the vehicle.

[0006]

According to the present invention, a main object as described above is to provide an observer based on the structure of claim 1, that is, an observer based on a vehicle model. based estimates the yaw rate of the vehicle body slip angle and the vehicle as a skid state quantity of the vehicle by feeding back the deviation between the actual yaw rate and the yaw rate as to estimate the lateral force of the front and rear wheels, the gain of the feedback of the vehicle body In a vehicle skidding state amount detection device including a first feedback gain for estimating a slip angle and a second feedback gain for estimating a yaw rate of the vehicle, a reference value of the vehicle is determined based on a state amount of the vehicle. calculating a yaw rate, the group
The larger the deviation between the quasi-yaw rate and the actual yaw rate is,
Means for calculating a saturation degree of the wheel lateral force based on the deviation between the reference yaw rate and the actual yaw rate as the saturation degree throat wheel lateral force is increased, the actual yaw in response to said saturation degree
Gain changing means for changing the first and second feedback gains so as to reduce the deviation between the rate and the estimated yaw rate to compensate for the non-linearity between the wheel slip angle and the wheel lateral force. This is achieved by a vehicle skid state quantity detection device characterized by having the following.

In general, there is a close relationship between the yaw rate of the vehicle and the slip angle of the vehicle body, and the change in the yaw rate reflects the change in the angular speed of the vehicle body slip angle. Reflect on changes in yaw rate. The yaw rate of the vehicle can be directly detected, and can be estimated by an observer based on a vehicle model based on the state quantity of the vehicle. Therefore, when estimating the lateral force of the front and rear wheels based on the state quantity of the vehicle including the actual yaw rate by the observer and estimating the slip angle and the yaw rate of the vehicle as the sideslip state quantity of the vehicle, the estimation error of the slip angle of the vehicle body is with checks by the estimation error of the yaw rate, if reducing the estimation error of the yaw rate by feeding back the deviation between the actual yaw rate and the estimated yaw rate,
The accuracy of estimating the slip angle of the vehicle body is improved.

Further, a reference yaw rate of the vehicle is calculated based on the state quantity of the vehicle, and a deviation between the reference yaw rate and the actual yaw rate is calculated.
Saryou is calculated saturation degree of the wheel lateral force based on the deviation amount between about wheel lateral force group <br/> quasi yaw rate and the actual yaw rate as the saturation degree becomes high large, for estimating a vehicle body slip angle The first feedback gain and the second feedback gain for estimating the yaw rate of the vehicle are calculated based on the difference between the actual yaw rate and the estimated yaw rate according to the degree of saturation.
The small change compensates for the non-linearity between the wheel slip angle and the wheel lateral force, thereby reducing the tie.
The lateral force of the front and rear wheels can be estimated with high accuracy even in the nonlinear region of the yaw lateral force.

According to the first aspect of the present invention, the observer is optimized simply by feeding back the deviation amount between the actual yaw rate and the estimated yaw rate, thereby reducing the estimation error of the vehicle body slip angle and the vehicle yaw rate. In addition to the reduction, the reference yaw rate of the vehicle is calculated based on the state quantity of the vehicle, and the reference yaw rate and the actual yaw rate are calculated.
The greater the deviation from the seat, the higher the degree of saturation of the wheel lateral force.
So as calculated saturation degree of the wheel lateral force based on the deviation between the reference yaw rate and the actual yaw rate, a second feedback for estimating a yaw rate of the first feedback gain and the vehicle for estimating a vehicle body slip angle Actual yaw rate and estimated yaw rate depending on the degree of saturation
Because non-linearity is compensated between the wheel slip angle and wheel lateral force by the deviation is changed to be smaller and, if irrespective feedback gain turning status of the vehicle is set to a constant and real Yaw rate and estimated yaw rate
Compared to the case where only the deviation of
It is possible to optimize the feedback gain and to estimate the lateral force of the front and rear wheels with high accuracy, thereby accurately estimating the slip angle and yaw rate of the vehicle body even in the linear region near the nonlinear region and the nonlinear region. As a result, it becomes possible to accurately estimate the amount of side slip state of the vehicle.

According to the present invention, in order to achieve the above-mentioned main object effectively, in the configuration of the first aspect, the gain changing means may be arranged so that the degree of saturation is in an area close to a turning limit of the vehicle. When the value is a corresponding value, the first and second feedback gains are changed so that the estimated slip angle of the vehicle body when the estimated yaw rate increases increases in a direction opposite to the estimated yaw rate. (The configuration of claim 2).

Generally, when the vehicle spins, both the slip angle and the yaw rate of the vehicle body increase, but the slip angle increases in the direction opposite to the yaw rate (in the direction opposite in sign).
According to the second aspect described above, so that in the estimated slip angle when the estimated yaw rate is increased at the non-linear region close to the linear area is the estimated yaw rate is increased in the opposite direction
Since the first and second feedback gains are changed, the estimation error of the lateral force of the front and rear wheels can be suppressed even when the deviation between the actual vehicle situation and the vehicle model becomes large, thereby reducing the side slip state amount. Is accurately estimated.

According to the present invention, the above-mentioned main problems are solved.
In order to achieve the effect effectively, in the configuration of claim 1,
ObserverIs the reference yaw rate and the actual yaw rate
The turning behavior of the vehicle determined based on the deviation
A) to reduce the error in estimating the lateral force of the front wheels
YoCorrect the estimated value of the front wheel lateral force according to the degree of saturation
However, when the turning behavior of the vehicle is in an oversteer state,
To reduce the estimation error of the rear wheel lateral forceDepending on the degree of saturation
Lateral force estimated value correcting means for correcting the estimated value of the lateral force of the rear wheel
With(The configuration of claim 3).

[0013] As will be described in detail below, it corrects the estimated value of the lateral force of the front wheels in accordance with the saturation degree to reduce the estimation error of the lateral force of the front wheels when the front wheels are assumed to be the limit,
If the rear wheel is estimated to be at its limit, the lateral force of the rear wheel is estimated according to the degree of saturation so as to reduce the estimation error of the lateral force of the rear wheel.
By correcting the constant value, the lateral force of the front and rear wheels can be estimated with high accuracy. Also it front wheels is the limit can be determined by turning behavior of the vehicle is in understeer condition, the rear wheels is the limit can be determined by turning behavior is oversteer, turning behavior Is understeer or oversteer
The state is the deviation between the reference yaw rate and the actual yaw rate
Ru can be determined by.

According to the configuration of the third aspect, when the turning behavior of the vehicle determined based on the deviation between the reference yaw rate and the actual yaw rate is in the understeer state, saturation is performed so that the estimation error of the lateral force of the front wheels is reduced. Front wheels according to degree
The lateral force estimation value is corrected so that the estimation error of the rear wheel lateral force is reduced when the turning behavior is in the oversteer state.
Since the estimated value of the lateral force of the rear wheel is corrected according to the degree of saturation, the estimated value of the lateral force of the wheel is determined according to the turning behavior of the vehicle.
Is closer to the linear region of the tire lateral force than when the
The accuracy of estimating the lateral force of the front and rear wheels in the nonlinear region or the nonlinear region is improved, and thereby the accuracy of estimating the amount of side slip state of the vehicle is improved.

According to the present invention, in order to effectively achieve the above-mentioned main object, in the configuration of the first aspect, each of the gain changing means may be provided at least in a range where a wheel slip angle is small. a first gain component is computed, a second gain component estimated slip angle of at the vehicle body when the estimated yaw rate is increased is calculated to increase in the opposite direction to the said estimated yaw rate, the reference Yo
When the turning behavior of the vehicle determined based on the deviation between the vehicle speed and the actual yaw rate is in the understeer state, the estimation error of the front wheel lateral force is reduced, and when the turning behavior is oversteer, the estimation error of the rear wheel lateral force is reduced. Means for calculating the first and second feedback gains as a weighted sum with a third gain component calculated so as to perform the third gain component when the degree of saturation is a value corresponding to a turning limit region of the vehicle. The weight of the gain component is set large, and when the saturation is a value corresponding to a region close to the turning limit of the vehicle, the weight of the second gain component is set large, and the saturation is set to Means for setting the weight of the first gain component large when the value corresponds to the stable turning area (the configuration of claim 4).

According to the configuration of the fourth aspect, the first and second feedback gains are at least the wheel slip.
First gain component calculated for small angle range
And the estimated vehicle body speed when the estimated yaw rate increases.
Acts to increase the lip angle in the opposite direction to the estimated yaw rate.
The calculated second gain component, the reference yaw rate and the actual yaw
The turning behavior of the vehicle determined based on the deviation from the rate
When the vehicle is in the dust steer state, the estimation error of the front wheel lateral force
When the turning behavior is oversteering,
It is calculated as a weighted sum with a third gain component calculated to reduce the force estimation error, and when the saturation degree is a value corresponding to the turning limit region of the vehicle, the weight of the third gain component is set to be large. When the degree of saturation is a value corresponding to a region close to the turning limit of the vehicle, the weight of the second gain component is set to be large, and when the degree of saturation is a value corresponding to the stable turning region of the vehicle, the first gain component is set. Is set to be large, so that the feedback gain is optimally optimized when the vehicle is in a stable turning area, in a situation near a turning limit, or in a turning limit area. Is set.

Further, according to the present invention, in order to effectively achieve the above-mentioned main object, in the configuration of the first aspect, the observer generates a first front-rear wheel lateral force based on the vehicle model. Means for estimating, means for estimating the second front and rear wheel lateral force based on the motion of the vehicle, and a lateral weight of the front and rear wheels as a weighted sum of the first and second front and rear wheel lateral forces. Lateral force estimating means for calculating an estimated value of force, wherein the lateral force estimating means has a saturation degree corresponding to a turning limit area of the vehicle .
Sideslip state quantity detecting device so constructed for vehicles and sets a high weight of the second front and rear wheels lateral force than when a value corresponding to the non-orbiting limit range when a that value (Configuration of Claim 5).

In general, when the vehicle is in a turning limit area, the accuracy of estimating the first front and rear wheel lateral force based on the vehicle model is poor, but the accuracy of estimating the second front and rear wheel lateral force based on the vehicle motion is good. It is believed that there is. According to the configuration of the fifth aspect, the first front and rear wheel lateral force is estimated based on the vehicle model, the second front and rear wheel lateral force is estimated based on the vehicle motion, and the first front and rear wheel lateral force is estimated. estimated value of the lateral force of the front and rear wheels is calculated as a weighted sum of the force and the second front and rear wheels lateral force, is a value corresponding to the non-orbiting limit range when the saturation degree is a value corresponding to the turning limit area of the vehicle Since the weight of the second front and rear wheel lateral force is set higher than sometimes, the lateral force of the front and rear wheels can be accurately estimated even at the time of the turning limit of the vehicle.

[0019]

Preferably, the means for calculating the degree of saturation calculates a reference yaw rate of the vehicle from at least the steering angle and the vehicle speed to estimate the lateral force.
The value correction means determines that the turning behavior is understeer when the magnitude of the actual yaw rate is smaller than the magnitude of the reference yaw rate, and the turning behavior is oversteer when the magnitude of the actual yaw rate is greater than the magnitude of the reference yaw rate. (Preferred mode 1).

[0020] In the above-mentioned arrangement of claim 4, means for calculating a saturation degree calculates a reference yaw rate of the vehicle from at least the steering angle and the vehicle speed, the gain changing means than the saturation degree first reference value When it is larger, it is determined to be a value corresponding to the turning limit area of the vehicle, and when the degree of saturation is smaller than the first reference value and larger than the second reference value, a value corresponding to the area close to the turning limit of the vehicle. configured to determine to be the (preferred embodiment 2).

Further, in the configuration of the above-mentioned claim 5, the lateral force
The estimating means sets the weight of the second wheel lateral force of the front wheel to be high when the actual yaw rate is smaller than the reference yaw rate, and sets the weight of the rear wheel when the actual yaw rate is larger than the reference yaw rate. The weight of the second wheel lateral force is set to be high (preferred mode 3).

[0022]

Prior to the description of the embodiment, the principle of estimating the slip angle of the vehicle body and the yaw rate of the vehicle in the present invention will be described.

The detected value of the yaw rate of the vehicle is γ, the feedback gain of the deviation (γ−γh) between the detected value γ of the yaw rate and the estimated value γh with respect to the estimated value βh of the slip angle of the vehicle is Kb, and the estimated value of the yaw rate is Deviation between the detected value γ of the yaw rate and the estimated value γh with respect to γh (γ-γh)
The feedback gain is Kg, the weight of the vehicle is m, the vehicle speed is V, the lateral forces of the left and right front wheels and the left and right rear wheels are Ff and Fr, respectively, and the distance between the center of gravity of the vehicle and the front and rear wheels in the longitudinal direction of the vehicle. Are respectively Lf and Lr, the derivative βhd of the estimated value βh of the slip angle of the vehicle and the derivative γhd of the estimated yaw rate γh of the vehicle are expressed by the following basic equations of Equations 1 and 2, respectively.

[0024]

## EQU1 ## βhd = (Ff + Fr) / (m * V) -γh-K
b (γ-γh)

## EQU2 ## γhd = (Lf * Ff−Lr * Fr) / Iz + K
g (γ-γh)

If the slip angles of the front and rear wheels are βf and βr, respectively, and the cornering powers of the front and rear wheels are Cf and Cr, respectively, according to the linear theory of the vehicle model, the lateral force Ff of the front and rear wheels is obtained. And Fr are represented by the following equations (3) and (4), respectively.

[0026]

## EQU3 ## Ff = Cf * βf

## EQU4 ## Fr = Cr * βr

As is well known, the cornering powers Cf and Cr are constant only when the slip angles βf and βr of the front and rear wheels are relatively small, and the slip angles βf and βr
Gradually decreases as the value increases. The estimated values βfh and βrh of the front and rear wheel slip angles βf and βr are the steering angle δf of the front wheel (which may be the average value of δfr and δfl), and the steering angle δr of the rear wheel (the average value of δrr and δrl). Can be estimated based on the estimated value βh of the slip angle of the vehicle body, the longitudinal distances Lf and Lr from the center of gravity of the vehicle to the front and rear wheels, the estimated value γh of the yaw rate, and the vehicle speed V. 5 and Equation 6

[0028]

Βfh = δf−βh−Lf * γh / V

## EQU6 ## βrh = δr−βh + Lr * γh / V

The estimated values βfh and βrh of Equations 5 and 6 above are substituted for βf and βr of Equations 3 and 4, respectively, and Equations 3 and 4 are substituted for the basic equations of Equations 1 and 2, respectively. When the equation is expressed in a matrix form, it is as shown in the following Expression 7.

(Equation 7)

Equation 7 can be expressed as Equation 8 below.

(Equation 8)

Equation 8 is further rewritten as Equation 9 below.

Xd = (A-LC) * X + (A-LC) (A-LC) ⁻¹ (B * δ + γ * K) = (A-LC) ｛X− (A-LC) ⁻¹ (− B * δ-γ * K)｝

Therefore, (A-LC) -1 (-B * δ-γ *
If K) is X c, Equation 9 can be rewritten as Equation 10 below.

(Equation 10)

Equation 10 can be solved so that X converges to Xc. Since this system is a quadratic system, two poles p1
And p2. Therefore, βc and γc are
It is expressed by the following equations 11 and 12, respectively, using 1 and p2.

[0034]

[Equation 11]

(Equation 12)

Note that βo and γo in the above equations (11) and (12) are defined as in the following equation (13).

(Equation 13)

The feedback gains Kb and Kg are calculated by using the above two poles p1 and p2,
4 and Equation 15 are represented. A11 and a12 are each
And the first and second columns of the first row of the matrix A in the above equation (7)
A21 and a22 are the components of the second row of the matrix A, respectively.
Components of the first and second columns .

[0037]

Kb = ｛(a11−p1−p2) + p1 * p2
｝ / A21 + a12

## EQU15 ## Kg = a11 + a22-p1-p2

When the wheel slip angles βf and βr are relatively small, the feedback gains Kb and Kg are
The first feedback gain components Kb1 and Kg1 are obtained as described in the specification of Japanese Patent Application No. 7-10782 filed by the present applicant.
The poles p1 and p2 are expressed by the following equations (16) and (17), respectively, with 1, C12, C21 and C22 being positive constants.

[0039]

## EQU16 ## p1 = -C11-C12 / V

## EQU17 ## p2 = -C21 -C22 / V

When the slip state of the wheels progresses as the vehicle spins, both the slip angle and the yaw rate of the vehicle body increase, but the slip angle of the vehicle body increases with a sign opposite to that of the yaw rate. Therefore, as the proportional coefficient of the yaw rate γ In relation number 11 is negative, the increasing direction estimate γh estimates βh is the yaw rate of the slip angle in other words if it is set to increase in the opposite, the actual Even when the deviation between the situation of the vehicle and the vehicle model becomes large, the estimation error is kept small, thereby improving the estimation accuracy of the slip angle of the vehicle. Since the estimated value γh of the yaw rate must converge to the detected value γ of the yaw rate,
Must be positive. Therefore, in the non-linear region, p1 and p2 are set so as to satisfy the following equations (18) and (19).

[0041]

(Equation 18)

[Equation 19]

The poles p1 and p2 satisfying the above two conditions
Are shown as values in the range indicated by hatching in FIGS. 15 and 16. In particular, FIG. 15 shows the range of poles p1 and p2 when the vehicle is running at low speed.
Numeral 6 indicates the range of poles p1 and p2 when the vehicle is running at high speed. The range of the poles p1 and p2 gradually changes from the range of FIG. 15 to the range of FIG. 16 as the vehicle speed increases.

According to the nonlinear theory of the vehicle model, the lateral forces Ff and Fr of the front wheels and the rear wheels are represented by the graph shown in FIG. Front and rear wheel slip angles βf and βr
Increases to near the value indicated by βm in FIG. 17, for example, and the proportional relation between the slip angles βf and βr of the front wheels and the rear wheels and the lateral forces Ff and Fr of those wheels is largely lost. Then, the estimation of the slip angle of the vehicle body is further modified.

Although the cornering powers Cf and Cr change every moment, the lateral forces Ff and Fr of the front and rear wheels can be conveniently expressed by the following equations (20) and (21). In the following equations (20) and (21), ΔFf and ΔFf
Fr is an estimation error including an error in the cornering power Cp and an estimation error in the friction coefficient μ of the road surface. Also shown in FIG.
As shown, Ff0 and Fr0 are not constants but functions of βfh and βrh, respectively, but the current values of βfh and βrh β
If we consider only the neighborhood of m, we can approximate these to constants.

[0045]

Ff = Cf * βfh + Ff0 + ΔFf

[Equation 21] Fr = Cr * βrh + Fr0 + ΔFr

When Ff and Fr in Equations 20 and 21 are substituted into Equations 1 and 2, and the results are expressed in a matrix format, the following Equation 22 is obtained.

(Equation 22)

The following equation (23) is obtained by Laplace transform of equation (22).
It is represented as

(Equation 23)

The lateral force estimated in the non-linear region of the tire lateral force, that is, the lateral force estimated in the limit region of the vehicle includes a large error. Therefore, by adjusting the feedback coefficient α,
ΔFf when the front wheel tire grip is saturated
When the rear wheel tire grip is in a saturated state, the transfer function from .DELTA.Fr to .beta.h is set to 0, whereby the estimation error of the slip angle .beta. Is reduced.

The feedback coefficient α for setting the transfer function from ΔFf to βh to 0 is expressed by the following equation (24).
The feedback coefficient α for setting the transfer function from ΔFr to βh to 0 is represented by the following equation 25.

[0050]

(Equation 24)

(Equation 25)

In the limit region of the vehicle, the cornering powers Cf and Cr of the front wheels and the rear wheels are all small values. Therefore, these values are approximated to 0, and s = 0 is set with emphasis on the steady component. Therefore, the feedback coefficient α of Expressions 24 and 25 is finally obtained by Expressions 26 and 27 below, respectively.
It becomes like.

[0052]

(Equation 26) At the time of the front wheel limit (understeer state) α = − (Iz * Kg) / (m * V * Lf)

[Equation 27] At the time of the rear wheel limit (in the oversteer state) α = (Iz * Kg) / (m * V * Lr)

[0053]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention;

FIG. 1 is a schematic configuration diagram (A) and a block diagram (B) showing one embodiment of a vehicle side slip state amount detection device according to the present invention, which is configured as a part of a vehicle turning behavior control device. is there.

In FIG. 1A, the turning behavior control device 1
Numeral 0 has a side slip state amount detecting device 12 and a braking force control device 14. The side slip state amount detecting device 12 calculates an estimated value βh of a vehicle body slip angle as a side slip state amount of the vehicle, as described later, and also calculates a yaw rate of the vehicle. Is calculated as γh,
The braking force control device 14 estimates the turning behavior of the vehicle based on the estimated value βh of the slip angle of the vehicle body, and outputs a control signal to the braking device 16 when the turning behavior is unstable such as spin. Left front wheel 18FL or right front wheel 18
FR, or any front wheel and left rear wheel 18RL and right rear wheel 18
The RR braking force is controlled to stabilize the turning behavior of the vehicle. Note that the control of the turning behavior of the vehicle itself does not form the gist of the present invention, and a detailed description thereof will be omitted.

A signal indicating the vehicle speed V is input from the vehicle speed sensor 20 to the side slip state amount detecting device 12, and a longitudinal acceleration sensor 22 and a lateral acceleration sensor 2 provided at the center of gravity of the vehicle are provided.
4, the longitudinal acceleration Gx and the lateral acceleration Gy of the vehicle are respectively obtained.
, A signal indicating the actual yaw rate γ of the vehicle is input from the yaw rate sensor 26, and a braking pressure Pbi (i = fr, fl, r) of each wheel is input from the pressure sensor 28 of each wheel.
r, rl), that is, a signal indicating the pressure in the wheel cylinder of each wheel is input. In addition, the four-wheel steering device 30 supplies the actual steering angle δ of the front wheels to the side slip state amount detection device 12.
f and a signal indicating the actual steering angle δr of the rear wheel are input, and the driving force Ti (i =
fr, fl, rr, rl).

As shown in FIG. 1 (B), the side slip state amount detecting device 12 receives the state amount of the vehicle such as the actual yaw rate γ and receives the deviation γ−γh between the actual yaw rate γ and the estimated yaw rate γh. The observer calculates the estimated value βh of the slip angle of the vehicle body and calculates the estimated value γh of the yaw rate by calculating the observer's lateral force of the front and rear wheels by estimating the lateral force of the front and rear wheels. It has a block 34 and a gain change block 36 that changes the gain of the feedback according to the state of the vehicle.

In particular, the feedback gain is a first feedback gain K for estimating the slip angle of the vehicle body.
b and a second feedback gain Kg for estimating the yaw rate of the vehicle. The gain changing block 36 calculates a reference yaw rate γt of the vehicle based on the state quantity of the vehicle, and calculates the actual yaw rate γ and the reference yaw rate γt deviation [gamma] t-gamma calculates a saturation degree Sa wheel lateral force based on the first and second feedback gains Kb and Kg changed according to the saturation degree, thereby the slip angle and wheel lateral force of a wheel with To compensate for the non-linearity between.

Although not shown in the figure, the sideslip state amount detecting device 12 and the braking force control device 14 actually include, for example, a central processing unit (CPU), a read only memory (ROM), and a random access memory (ROM). RAM),
An input / output port device may be provided, which may include a microcomputer and a drive circuit connected to each other by a bidirectional common bus.

The side slip state amount detecting device 1 of the illustrated embodiment
2 is an estimated value βh of the slip angle of the vehicle body and an estimated value γh of the yaw rate of the vehicle according to the general flow shown in FIG.
Is calculated. The routine shown in FIG. 2 is repeatedly executed at predetermined time intervals.

First, at step 100, a signal indicating the vehicle speed V is read, and the saturation degree Sa and the road surface friction, which are indicators of the degree of tire grip saturation, are read in accordance with the routine shown in FIG. An estimation error Δμ of the coefficient μ is calculated. In step 200, the first tire lateral force is calculated based on the vehicle model according to the routine shown in FIG. 4, and the difference between the braking / driving forces of the right and left front wheels and the left and right rear wheels is substantially calculated. A second tire lateral force is calculated based on the dependent yaw moment M.

In step 300, the friction coefficient μ of the road surface is estimated in accordance with the routine shown in FIG.
This estimation is repeatedly adjusted by comparing the first tire lateral force calculated based on the vehicle model with the second tire lateral force calculated based on the yaw moment M.

In step 400, the feedback gains Kb and Kg are calculated according to the routine shown in FIG. 6, and in step 500, the observer is calculated according to the routine shown in FIG. Thus, the estimated value βh of the slip angle of the vehicle body and the estimated value γh of the yaw rate are calculated.

In step 110 of the routine for calculating the estimation error Δμ of the degree of saturation Sa and the coefficient of friction μ of the road surface shown in FIG. 3, Kh is used as a stability factor, H is used as a wheel base, and the vehicle speed V, Front wheel actual steering angle δf
The target yaw rate γc is calculated according to the following equation 28 based on the actual steering angle δr of the rear wheel and the reference yaw rate γt according to the following equation 29 using Tt as a time constant and s as a Laplace operator. Incidentally, the target yaw rate γc may be calculated in consideration of the lateral acceleration Gy of the vehicle in consideration of a dynamic yaw rate.

[0065]

Γc = V * (δf−δr) / ｛(1 + Kh *)
V ² ) * H｝

Γt = γc / (1 + Tt * s)

In step 120, the following equation 30
Between the actual yaw rate γ and the reference yaw rate γt
A yaw rate deviation Δγ based on the amount γt−γ is calculated.

Δγ = (γt−γ) / V

In step 130, the degree of saturation Sa is calculated from a map corresponding to the graph shown in FIG. 8 based on the absolute value of the yaw rate deviation Δγ. The saturation Sa increases as the absolute value of the yaw rate deviation Δγ increases until the tire grip is saturated. That is, low values
The degree of harmony Sa is in the linear region of the wheel lateral force (the stable turning area of the vehicle).
Area), the high value of the degree of saturation Sa is the non-linearity of the wheel lateral force.
Corresponding to the shape region (the turning limit region of the vehicle)
The degree of harmony Sa is a non-linear region (vehicle area) close to the linear region of the wheel lateral force.
(Area near the turning limit area of the vehicle). Step 1
In step 40, an estimated error Δμ of the friction coefficient μ of the road surface is calculated from a map corresponding to the graph shown in FIG. 9 based on the degree of saturation Sa. Note that the estimation error Δμ is the saturation degree S
It decreases as a increases.

In step 210 of the first and second tire lateral force calculation routine shown in FIG. 4, Lf and L
r is the distance in the vehicle longitudinal direction from the center of gravity of the vehicle to the axles of the front and rear wheels, respectively, and the vehicle speed V and the actual steering angle δf of the front wheels
And the actual steering angle δr of the rear wheel, the estimated value βh of the slip angle of the vehicle body calculated in the previous cycle, and the estimated value γh of the yaw rate calculated in the previous cycle, 32, the slip angle βi of each wheel (i =
fr, fl, rr, rl) are calculated.

[0069]

Βfr = βfl = δf−βh−Lf * γh / V

(32) βrr = βrl = δr-βh + Lr * γh / V

In step 220, B is applied to the brake oil pressure Pbi (i = fr, fl, rr, rl) of each wheel and the braking force of each wheel, that is, the longitudinal force Fxi (i = fr, fl, rr, rl). ), The brake hydraulic pressure Pbi of each wheel and the driving force Ti
, The longitudinal force Fxi of each wheel is calculated according to the following equation 33.

Fxi = B * Pbi-Ti

In step 230, the load Wi (i = fr, fl, rr, rl) of each wheel is calculated from the predetermined weight m of the vehicle, the longitudinal acceleration Gx of the vehicle, and the lateral acceleration Gy of the vehicle. At the same time, the limit lateral force Fymaxi (i = fr, fl, rr, rl) of each wheel is calculated according to the following Expression 34. In the following Expression 34, μ is an estimated value of the road surface friction coefficient calculated in the previous cycle.

Fymaxi = ｛(μ * Wi) ² −Fxi ² ｝ ^1/2

In step 240, Cpi (i = f
r, fl, rr, rl) as the cornering power of each wheel,
According to the following equation 35, the lateral force Fyi (i = fr, fl, r) of each wheel
r, rl) are calculated. The lateral force Fyi of each wheel has a slope of Cpi.
May be calculated based on the slip angle βi of each wheel from a map corresponding to the graph shown in FIG. 10 showing a curve tangent to the straight line Lcp.

Fyi = Fymaxi * tanh (Cpi * βi / Fymaxi)

In step 250, the first estimated lateral force values Fyf1 and Fyr1 for the front and rear wheels based on the vehicle model are calculated according to the following equations (36) and (37).

[0074]

[Formula 36] Fyf1 = Fyfl + Fyfr

[Equation 37] Fyr1 = Fyrl + Fyrr

In step 260, the yaw moment M due to the braking / driving force difference between the left and right wheels is calculated according to the following equation 38, where T is the tread of the vehicle.

M = (Fxfr−Fxfl + Fxrr−Fxrl) * T / 2

[0076] The In step 270, the yaw inertia moment of the vehicle to Iz, as the differential value of the yaw rate γ of Ganmadif, respectively car according to the number 39 and number 40 the following
Second estimated lateral force Fyf for front and rear wheels based on vehicle motion
2 and Fyr2 are calculated.

[0077]

Fyf2 = (Lr * Gy * 9.8 * m + Iz *
γdif-M) / H

Fyr2 = (Lf * Gy * 9.8 * m-Iz *
γdif + M) / H

In step 310 of the road friction coefficient estimating routine shown in FIG. 5, the ratio of the second estimated lateral force to the first estimated lateral force is estimated in the previous cycle. By assuming the ratio of the friction coefficient of the true road surface to the friction coefficient of the road surface, estimated values μtmpf and μtmtr of the road surface friction coefficient for the front wheels and the rear wheels are calculated according to the following Expressions 41 and 42, respectively. In Equations 41 and 42 below, Fxf is the front-rear force of the left and right front wheels (Fxfr + F
xfl), and Fxr is the longitudinal force of the left and right rear wheels (Fxrr + Fxr)
l).

[0079]

[Number 41] ^{μtmpf = μ * (Fyf2 2 +} Fxf 2) 1/2] /
(Fyf1 ² + Fxf ^{2) 1/2}

[Equation 42] μtmpr = μ * (Fyr2 ² + Fxr ² ) ^1/2 ] /
(Fyr1 ² + Fxr ^{2) 1/2}

In step 320, step 31
Estimated value μ for front wheel and rear wheel calculated at 0
The larger value of tmpf and μtmpr is selected as the estimated value μtmp of the road surface friction coefficient. The larger of the two estimated values μtmpf and μtmpr is selected as the estimated value μtmp of the friction coefficient of the road surface because if the friction coefficient of the road surface is estimated to be lower than the actual value, the vehicle This is because there is a risk that the slip angle of the vehicle body is estimated to be an excessive value by the behavior control, and the behavior control of the vehicle is inappropriately performed.

In step 330, the graph shown in FIG. 11 is used based on the saturation Sa so that the filter time constant Tm for filtering the estimated value μtmp of the friction coefficient of the road surface decreases as the saturation Sa increases. The filter time constant Tm is calculated from the map corresponding to the equation (1), and in step 340, the filter coefficient R is calculated according to the following equation 43 using Tsp as the sampling time.

R = Tsp / Tm

In step 350, the following equation
The estimated value μh of the friction coefficient of the road surface is calculated by performing the filtering process according to the following equation. In step 360, the estimated value μh of the friction coefficient is calculated according to the following equation 45.
The estimated friction coefficient μ of the road surface after correction is calculated as the sum of the estimated error Δμ calculated in step 140.

[0083]

Μh = (1−R) * μh + μtmp * R

[Equation 45] μ = μh + Δμ

In the feedback gain Kb for estimating the slip angle of the vehicle body and the feedback gain Kg for estimating the yaw rate shown in FIG. 6, the feedback gain Kb is calculated by the weighted sum.
And Kg, the first feedback gain components Kb1 and Kg1, and the second feedback gain component K
b2 and Kg2 and third feedback gain components Kb3 and Kg3 are calculated.

First, in step 410, the above equation (1)
Based on p1 and p2 calculated according to Equations 5 and 16, the following Equation 46 corresponding to Equations 13 and 14, respectively.
And the first feedback gain component K according to
b1 and Kg1 are calculated. This first feedback
The gain component is in the range where the wheel slip angle is small as described above.
Is a gain component calculated for

[0086]

Kb1 = ｛(a11−p1−p2) + p1 * p2
｝ / A21 + a12

Kg1 = a11 + a22−p1−p2

In step 420, parameters p1 and p2 for calculating the second feedback gain components Kb2 and Kg2 are calculated. As described above, the parameters p1 and p2 are calculated to values within the range indicated by hatching in the graph of FIG. 15 when the vehicle is traveling at a low speed, and are indicated by hatching in the graph of FIG. 16 when the vehicle is traveling at a high speed. Operates on a range of values.

In step 430, the second feedback gain components Kb2 and Kg2 are calculated based on the parameters p1 and p2 in accordance with the following equations (48) and (49), respectively. Note that this second feedback gain
The components will be increased as the yaw rate estimate increases, as described above.
The estimated value of the slip angle of the vehicle body
Is a gain component calculated to increase in the reverse direction.

[0089]

Kb2 = ｛(a11−p1−p2) + p1 * p2
｝ / A21 + a12

Kg2 = a11 + a22-p1-p2

In step 440, the third feedback gain components Kb3 and Kg3 are calculated according to the following equations 50 and 51, using τ as a constant. This third
The feedback gain component is the turning behavior of the vehicle as described above.
When the vehicle is in the understeer state, the estimation of the front wheel lateral force is incorrect.
When the difference is reduced and the turning behavior is oversteer, the rear wheels
Component calculated to reduce the estimation error of lateral force
And the following Equation 50 corresponds to Equations 26 and 27 above.

[0091]

Kb3 =-(1 + α) When Δγ * γ> 0, α = − (Iz * Kg3) / (m *
V * Lf) When Δγ * γ <0, α = (Iz * Kg3) / (m * V
* Lr)

[Formula 51] Kg3 = 1 / τ

In step 450, the saturation degree Sa
From the map corresponding to the graph shown in FIG. 12 based on the weights of the first to third feedback gain components Wg1,
Wg2 and Wg3 are calculated, and in step 460, the first to third feedback gain components Kb1 and Kg1, Kb2 and Kg according to the following Expressions 52 and 53, respectively.
2. Feedback gains Kb and Kg are calculated as a weighted sum of Kb3 and Kg3.

[0093]

[Equation 52] Kb = Wg1 * Kb1 + Wg2 * Kb2 + Wg3 * Kb3

Kg = Wg1 * Kg1 + Wg2 * Kg2 + Wg3 * Kg3

In step 510 of the observer calculation routine shown in FIG. 7, it is determined whether Δγ * γ is positive or not, and whether the front wheels are in the limit state and the vehicle is in the understeer state is determined. When the negative determination is made, in other words, when it is determined that the rear wheels are in the limit state and the vehicle is in the oversteer state, the process proceeds to step 520, and the affirmative determination is made. If so, the process proceeds to step 540.

In step 520, as the saturation degree Sa becomes higher than the map corresponding to the graph shown in FIG.
Etc. weight W of the second estimated lateral force Fyr2 of the rear wheel to be larger
dr is calculated, and in step 530, the lateral force Fyf of the front wheel and the rear wheel is calculated according to the following Expressions 54 and 55, respectively.
And Ffr are calculated.

[0096]

Fyf = Fyf1

Fyr = (1-Wdr) * Fyr1 + Wdr * Fyr2

Similarly, in step 540, FIG.
From the map corresponding to the graph shown in Fig.
The weight Wdf of the second estimated lateral force Fyf2 of the front wheel is calculated so as to increase as the height increases , and in step 550, the lateral forces Fyf and Fyr of the front wheel and the rear wheel are calculated according to the following equations 56 and 57, respectively. You.

[0098]

Fyf = (1-Wdf) * Fyr1 + Wdf * Fyf2

Fyr = Fyr1

In step 560, the following equation 58
The estimated value βh of the slip angle of the vehicle and the estimated yaw rate γh of the vehicle are calculated by performing the calculation of the observer in accordance with the equation (59).

[0100]

Βh = βh + ｛(Fyf + Fyr) / (m * V)
−γh + Kb (γ−γh)｝ * Tsp

Γh = γh + ｛(Lf * Fyf−Lr * Fyr +
M) / Iz + Kg (γ-γh)｝ * Tsp

Thus, in the illustrated embodiment, the functions of the observer block 34 are achieved by steps 100, 200, and 500, whereby the lateral forces Fyf and Fyr of the front wheels and the rear wheels are calculated, and the slip of the vehicle body is calculated. The angle estimation value βh and the yaw rate estimation value γh are calculated, and the functions of the gain changing block 36 are achieved in steps 100 to 400, whereby the feedback gains Kb and Kg are set according to the state of the vehicle.

In particular, in step 100, that is, in steps 110 and 120 in the calculation routine of the estimation error of the degree of saturation and the friction coefficient μ of the road surface shown in FIG. 3, the deviation amount between the reference yaw rate γt and the actual yaw rate γ is calculated. The yaw rate deviation Δγ is calculated, and in step 130, the degree of saturation Sa is calculated so as to increase as the magnitude of the yaw rate deviation Δγ increases. In step 140, the saturation degree Sa decreases as the degree of saturation Sa increases. An estimation error Δμ of the friction coefficient μ is calculated.

Step 200, that is, step 21 of the first and second tire lateral force calculation routines shown in FIG.
At 0, the slip angle βi of each wheel is calculated, the longitudinal force Fxi of each wheel is calculated at step 220, the limit lateral force Fymaxi of each wheel is calculated at step 230, and at step 240 The lateral force Fyi of each wheel is calculated, and in step 250, the first estimated lateral force F of the front wheel and the rear wheel is calculated.
yf1 and Fyr1 are calculated. Further, in step 160, the yaw moment M due to the difference between the braking / driving force of the left and right wheels is calculated, and in step 270, the second estimated lateral force values Fyf2 and Fyr2 of the front and rear wheels are calculated.

In step 300, that is, in step 310 of the road friction coefficient estimating routine shown in FIG. 5, the estimated values μtmpf and μtmpr of the road friction coefficient are calculated, and in step 320, the two estimated values are obtained. Is selected as μtmp, the filter time constant Tm is calculated in step 330, the filter coefficient R is calculated in step 340, and the filter processing is performed in step 350, The estimated value μh of the road surface friction coefficient is calculated, and in step 360, the corrected estimated value μ of the road surface friction coefficient corrected by the estimated error Δμ of the road surface friction coefficient is calculated.

In step 400, that is, in step 410 of the feedback gain calculation routine shown in FIG. 6, the first feedback gain components Kb1 and Kg1 are calculated, and in steps 420 and 430, the second feedback gain components are calculated. Kb2 and Kg2 are calculated, and in step 440, the third feedback gain component K
b3 and Kg3 are calculated. In step 450, the weights Wg1, Wg2, and Wg3 of the first to third feedback gain components are calculated based on the saturation degree Sa.
The feedback gains Kb and Kg are calculated as weighted sums of the first to third feedback gain components.

Further, at step 500, that is, at step 510 of the observer calculation routine shown in FIG. 7, it is determined whether or not the turning behavior of the vehicle is in an understeer state, that is, whether or not the front wheels are at a limit state. When it is determined that the behavior is in the oversteer state, that is, when the rear wheel is in the limit state, the weight Wdr of the second estimated lateral force of the rear wheel is calculated in step 520 so as to increase as the saturation degree Sa increases. In step 530, the lateral forces Fyf and Fyr of the front and rear wheels are calculated.

When it is determined in step 510 that the turning behavior of the vehicle is in the understeer state, that is, that the front wheel is in the limit state, in step 540 the second wheel of the front wheel becomes larger as the degree of saturation Sa becomes higher. Is calculated, and in step 550, the lateral forces Fyf and Fyr of the front and rear wheels are calculated. Ie step
The turning behavior of the vehicle is understeered by 510 to 550
To reduce the estimation error of the front wheel lateral force when
Correct the estimated value of the front wheel lateral force according to the degree of saturation, and
When the turning behavior is in the oversteer state, the lateral force of the rear wheel
Lateral force of the rear wheels according to the degree of saturation to reduce the estimation error
The function of the lateral force estimated value correction means for correcting the estimated value
It is. Then, in step 560, the estimated value βh of the slip angle of the vehicle body and the estimated value γh of the yaw rate are calculated by performing the calculation of the observer.

As can be understood from the above description, according to the illustrated embodiment, the vehicle is in the stable turning area, in the area close to the turning limit, or in the turning limit area in any case. And the second feedback gain can be optimally set, so that even when the deviation between the actual vehicle situation and the vehicle model becomes large, the estimation error of the lateral force of the wheels can be suppressed to a small value. If it is regardless of the feedback gain in turning behavior of a constant and Jitsuyo
Only the amount of deviation between the estimated
Compared with the case where the Dobakku, vehicle is also accurately estimate the lateral force of the front and rear wheels when a turning limit region or a region close thereto, thereby the accuracy of the vehicle body slip angle and the yaw rate as a skid state quantity Can be estimated well.

In general, when it is estimated that the friction coefficient of the road surface is low in spite of the fact that the friction coefficient of the actual road surface is high, the estimated value βh of the slip angle of the vehicle body becomes excessively large. Is no longer controlled. Conversely, at the turning limit of the vehicle, it is almost impossible to assume that the friction coefficient of the road surface is high even though the friction coefficient of the actual road surface is low, so the estimated value βh of the slip angle of the vehicle body becomes too small and the vehicle Is not stopped. Therefore, as in this embodiment, the friction coefficient is corrected to be relatively large by adding the estimated error evaluation value Δμ to the estimated value μh of the road surface friction coefficient, and the corrected value μ is used as the road surface friction coefficient for the calculation in step 230. By using this, it is possible to reduce the possibility that the lateral forces of the front and rear wheels are erroneously estimated, thereby reducing the possibility that the slip angle and the yaw rate of the vehicle body are erroneously estimated.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments may be included within the scope of the present invention. It will be clear to those skilled in the art that is possible.

[0111]

As is apparent from the above description, according to the configuration of the first aspect of the present invention, the observer is optimized by feeding back the deviation between the actual yaw rate and the estimated yaw rate. In addition to reducing the estimation error of the yaw rate of the vehicle, the deviation amount between the reference yaw rate and the actual yaw rate is large.
The reference yaw rate is set so that the greater the degree of saturation of the wheel lateral force
Saturation of the wheel lateral force based on the deviation between the speed and the actual yaw rate
The degree is calculated and the deviation between the actual yaw rate and the estimated yaw rate is calculated.
The first feedback gain for estimating the slip angle of the vehicle body and the second feedback gain for estimating the yaw rate of the vehicle are changed in accordance with the degree of saturation of the wheel lateral force so that the difference becomes small, so that the wheel Since the nonlinearity between the slip angle and the lateral force of the wheel is compensated, the feedback gain is set to be constant regardless of the turning condition of the vehicle, and the deviation amount between the actual yaw rate and the estimated yaw rate
Only in comparison with the case where the feedback Fidoba
Optimum vehicle gain and the lateral force of the front and rear wheels can be estimated with high accuracy. This makes it possible to estimate the vehicle body slip angle and yaw rate with high accuracy even in the linear region near the nonlinear region and the nonlinear region. Can be accurately estimated.

According to the configuration of the second aspect, the estimated slip angle when the estimated yaw rate increases in the non-linear region close to the linear region of the wheel lateral force increases in the direction opposite to the estimated yaw rate. Since the first and second feedback gains are changed as described above, the estimation error of the lateral force of the front and rear wheels can be reduced even when the deviation between the actual vehicle situation and the vehicle model becomes large. It is possible to accurately estimate the amount of sideslip state.

According to the third aspect of the present invention, when the turning behavior of the vehicle is in the understeer state, the lateral error of the front wheel is reduced according to the degree of saturation so that the estimation error of the lateral force of the front wheel is reduced.
When the estimated force is corrected and the turning behavior is in the oversteer state, saturation is performed so that the estimation error of the lateral force of the rear wheel is reduced.
Since the estimated value of the lateral force of the rear wheel is corrected according to the degree, the estimated value of the lateral force of the wheel is corrected according to the situation of the turning behavior of the vehicle
Non-linearity closer to the linear region of tire lateral force than when not
The accuracy of estimating the lateral force of the front and rear wheels in the shape region and the non-linear region can be improved, thereby improving the accuracy of estimating the amount of side skid of the vehicle.

Further, according to the configuration of the fourth aspect, the vehicle may be in a stable turning area, in a state close to a turning limit, or in a turning limit area. Can also optimally set the feedback gain, thereby optimizing the observer regardless of the turning situation of the vehicle.

According to the configuration of the fifth aspect, the first front and rear wheel lateral force is estimated based on the vehicle model, and the second front and rear wheel lateral force is estimated based on the motion of the vehicle. An estimated value of the lateral force of the front and rear wheels is calculated as a weighted sum of the lateral force of the front and rear wheels and the lateral force of the second front and rear wheels. Is set high, the lateral force of the front and rear wheels can be accurately estimated even at the time of the turning limit of the vehicle.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram (A) and a block diagram (B) showing one embodiment of a vehicle side slip state amount detection device according to the present invention configured as a part of a vehicle turning behavior control device.
It is.

FIG. 2 is a general flowchart showing a side slip state amount calculation routine in the embodiment.

FIG. 3 is a flowchart showing a calculation routine of an estimation error of a degree of saturation and a friction coefficient μ of a road surface in the embodiment.

FIG. 4 is a flowchart illustrating first and second tire lateral force calculation routines in the embodiment.

FIG. 5 is a flowchart showing a routine for estimating a road surface friction coefficient μ in the embodiment.

FIG. 6 is a flowchart showing a routine for calculating feedback gains Kb and Kg in the embodiment.

FIG. 7 is a flowchart illustrating an observer calculation routine according to the embodiment.

FIG. 8 shows the absolute value of the deviation Δγ of the yaw rate and the saturation degree Sa.
6 is a graph showing the relationship between

FIG. 9 shows an estimation error Δ of the saturation degree Sa and the friction coefficient μ of the road surface.
6 is a graph showing a relationship between μ and μ.

FIG. 10 is a graph showing a relationship between a slip angle βi of each wheel and a lateral force Fyi of each wheel.

FIG. 11 is a graph showing a relationship between a saturation degree Sa and a time constant Tm.

FIG. 12 shows the saturation degree Sa and the weights Wg1, Wg2,
It is a graph which shows the relationship with Wg3.

FIG. 13 is a graph showing a relationship between a saturation degree Sa and a weight Wdr.

FIG. 14 is a graph showing a relationship between a saturation degree Sa and a weight Wdf.

FIG. 15 is a graph showing appropriate ranges of second feedback gain calculation parameters p1 and p2 when the vehicle is running at a low speed.

FIG. 16 is a graph showing appropriate ranges of second feedback gain calculation parameters b1 and p2 when the vehicle is running at high speed.

FIG. 17 is a graph showing a relationship between slip angles βf and βr of front wheels and rear wheels and lateral forces Ff and Fr.

[Description of Signs] 10: Turning behavior control device 12: Side slip state amount detection device 14: Braking force control device 16: Brake device 18FL-18RR: Wheels 34: Observer block 36: Gain change block

Claims (5)

(57) [Claims] An observer based on a vehicle model includes an observer that estimates a lateral force of front and rear wheels based on a state quantity of the vehicle including an actual yaw rate, and feeds back a deviation amount between the actual yaw rate and the estimated yaw rate. The slip angle of the vehicle body and the yaw rate of the vehicle are estimated as the sideslip state amount, and the feedback gain is a first feedback gain for estimating the slip angle of the vehicle body and a second feedback gain for estimating the yaw rate of the vehicle. In a vehicle skid state amount detection device including a feedback gain, a reference yaw rate of the vehicle is calculated based on the state amount of the vehicle, and the reference yaw rate and the actual yaw rate are calculated.
The greater the deviation from the vehicle, the higher the degree of saturation of the wheel lateral force.
The difference between the reference yaw rate and the actual yaw rate
Means for calculating the degree of saturation of the wheel lateral force based on the amount , and a bias between the actual yaw rate and the estimated yaw rate according to the degree of saturation.
And a gain changing means for changing the first and second feedback gains so as to reduce the difference and compensating for a non-linearity between a wheel slip angle and a wheel lateral force. Quantity detection device. 2. The vehicle according to claim 1, wherein said gain changing means increases said estimated yaw rate when said degree of saturation is a value corresponding to a region close to a turning limit of said vehicle. A side slip state detection device for a vehicle, wherein the first and second feedback gains are changed so that an estimated slip angle of the vehicle body in the case increases in a direction opposite to the estimated yaw rate. 3. An apparatus according to claim 1, wherein the observer is configured to detect the front wheel when the turning behavior of the vehicle, which is determined based on a deviation between the reference yaw rate and the actual yaw rate, is in an understeer state. To reduce the lateral force estimation error, the lateral force of the front wheels is estimated according to the degree of saturation.
The constant value is corrected, and when the turning behavior of the vehicle is in an oversteer state, the saturation is reduced so as to reduce the estimation error of the lateral force of the rear wheels.
Lateral force estimation that corrects the estimated value of the lateral force of the rear wheels according to the degree of sum
Sideslip state quantity detecting apparatus of the vehicle, characterized in that it have a value correcting means. 4. A vehicle skidding state quantity detecting device according to claim 1, wherein said gain changing means comprises:
A first gain component that is calculated for a range in which the wheel slip angle is small, and a second gain component that is calculated so that the estimated slip angle of the vehicle body when the estimated yaw rate increases increases in a direction opposite to the estimated yaw rate. When the turning behavior of the vehicle determined based on the second gain component and the deviation between the reference yaw rate and the actual yaw rate is in the understeer state, the estimation error of the lateral force of the front wheel is reduced, and when the turning behavior is oversteer, the rear wheel is oversteered. Means for calculating the first and second feedback gains as a weighted sum with a third gain component calculated to reduce the estimation error of the lateral force of the vehicle, and the degree of saturation corresponds to a turning limit area of the vehicle.
When the value of the third gain component is large, the weight of the second gain component is set large when the degree of saturation is a value corresponding to a region close to the turning limit of the vehicle. Means for setting the weight of the first gain component to be large when the degree of saturation is a value corresponding to the stable turning area of the vehicle. 5. An apparatus according to claim 1, wherein said observer estimates a first front-rear wheel lateral force based on said vehicle model and a second means based on said vehicle motion. Means for estimating the lateral force of the front and rear wheels, and lateral force estimating means for calculating an estimated value of the lateral force of the front and rear wheels as a weighted sum of the first and second lateral force of the front and rear wheels. a, the lateral force estimation means corresponds to the non-orbiting limit range when the saturation degree is a value corresponding to the turning limit area of the vehicle
The weight of the second front and rear wheel lateral force is set to be higher than the value of the vehicle front skid state quantity.