JP3426512B2 - Vehicle turning behavior state detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turning motion control system for a vehicle.
In order to improve control accuracy,
Turning behavior of a vehicle that accurately detects turning behavior
The present invention relates to a state detection device. [0002] 2. Description of the Related Art Conventionally, vehicle motion control (for example,
Control, antilock brake control, etc.)
There is something that detects the turning behavior state of the vehicle,
As a method of detecting the turning behavior state, for example,
JP-A-2-70561 and JP-A-5-155323
Some have already been disclosed in Japanese Patent Publication No. [0003] SUMMARY OF THE INVENTION In the above prior art,
The detected yaw rate obtained by the yaw rate detecting means and the steering angle
The steering angle detected by the detection means and the vehicle speed detection means
A standard yaw rate based on the detected vehicle speed
To determine the turning behavior of the vehicle based on the difference
are doing. However, the norm yaw rate is
Since it is determined based on the state where the number is high,
When driving on a road with a low coefficient of friction, the standard yaw
The turning point does not correspond to the road surface condition and the turning behavior is detected.
Becomes inaccurate. [0004] The present invention has been made in view of such circumstances.
Therefore, the turning behavior of the vehicle is changed so that the coefficient of friction of the road surface is low.
Turning behavior of the vehicle that can be accurately detected even in the state
An object of the present invention is to provide a state detection device. [0005] [MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
Further, the present invention provides a vehicle speed detecting means for detecting a vehicle speed.
And yaw rate detection means for detecting yaw rate;
Front and rear wheel slip angles based on the sideslip angle of
Wheel slip angle calculating means for calculating the slip angle and road surface friction.
Friction coefficient estimating means for estimating a friction coefficient;
Front and rear wheel slip angles obtained by the angle calculation means,
The vehicle speed detected by the vehicle speed detecting means and the vehicle speed
It is determined based on the friction coefficient estimated by the friction coefficient estimation means.
Front wheel slip angle limit and rear wheel slip angle limit
Determining means for determining the turning behavior state of the vehicle by comparing with
And;The determination means determines that the front wheel slip angle is
Rear wheel slip angle exceeds the limit value
The vehicle is out of course when the angle limit is exceeded
The front wheel slip angle is the front wheel slip angle limit value
And the rear wheel slip angle is below the rear wheel slip angle limit
When the vehicle is in a state of understeer,
Also, the front wheel slip angle is less than the front wheel slip angle limit value.
And the rear wheel slip angle exceeds the rear wheel slip angle limit value
When the vehicle is over-steering,
Also, the front wheel slip angle is less than the front wheel slip angle limit value.
And the rear wheel slip angle is equal to or less than the rear wheel slip angle limit value.
Sometimes it is determined that the vehicle is in a normal turning state
DoIt is characterized by the following. Here, the wheel slip angle depends on the direction of the wheel.
This is the angle between the direction of travel of the wheels and this slip.
Wheel grind on the road surface according to the angle and the coefficient of friction of the road surface
The tap force changes. On the other hand, the side slip angle of the vehicle
Is the angle between the direction of travel of the vehicle and the
As the turning motion and the friction coefficient of the road surface change,
Turning behavior of the vehicle according to the change in the grip force of the wheels
It is shown. On the other hand, the vehicle speed and road friction
The limit value of the wheel slip angle can be known in advance according to the number
The front wheel slip calculated based on the sideslip angle of the vehicle body
And rear wheel slip angles, and the limit of the wheel slip angles.
The vehicle's turning behavior is detected by comparing the
It is possible to issueThat is, the front wheel slip angle is
Slip angle limit value is exceeded and rear wheel slip angle is rear wheel slip.
When the vehicle exceeds the limit angle, the vehicle goes out of course.
State, and the front wheel slip angle is set to the front wheel slip angle.
The rear wheel slip angle exceeds the slip angle limit value and the rear wheel slip angle
When the vehicle is below the limit, the vehicle is slightly understeered
And the front wheel slip angle is equal to the front wheel slip angle.
The rear wheel slip angle is below the limit value and the rear wheel slip angle
The vehicle is oversteering when the limit is exceeded
And the front wheel slip angle is set to the front wheel slip.
Rear wheel slip angle is less than or equal to
Vehicle is in a normal turning state
Can be determined to be. Moreover, the wheel slip angle
Is estimated according to the change in the coefficient of friction of the road surface,
Accurate vehicle turning behavior reflecting road surface friction coefficient
Can be detected. [0007] Embodiments of the present invention will be described below.
A description will be given based on one embodiment of the present invention shown in the accompanying drawings. FIGS. 1 to 10 show an embodiment of the present invention.
FIG. 1 shows the drive system and the brake system of a vehicle.
FIG. 2 is a block diagram showing the configuration of the control unit;
FIG. 3 shows the tire characteristics set by the tire characteristic setting means.
FIG. 4 shows the calculation of the wheel slip angle in the control unit.
FIG. 5 is a block diagram showing the configuration of the means, and FIG.
Diagram showing lateral force balance in model, FIG. 6 is linear
FIG. 7 shows tire characteristics used in a two-wheel vehicle motion model.
FIG. 8 is a block diagram showing a configuration of friction coefficient estimating means, and FIG.
Cornering force and braking / driving during both turning movements
FIG. 9 is a view showing a vehicle body moment generated by a force, and FIG.
FIG. 10 is a block diagram showing the configuration of a means for determining the turning behavior of the vehicle.
Is the vehicle body speed and friction coefficient
It is a figure showing a setting map according to it. First, in FIG.
A power unit P including an engine E and a transmission T is mounted.
Power from the power unit P
Left and right rear wheels that are drive wheels via shaft S and differential device D
W_RL, W_RRIs transmitted to Left and right front wheels W_FL, W_FRTo
Is the left and right front wheel brakes B_FL, B_FRIs attached,
Left and right rear wheels W_RL, W_RRHas left and right rear wheel brakes B
_RL, B_RRIs mounted, and each wheel brake B_FL, B_FR,
B_RL, B_RRIs, for example, a disc brake. The tandem type master cylinder M has the
Brake pedals from the first and second output ports 2A and 2B
The brake fluid pressure is output in accordance with the depressing operation of
And both output ports 2A and 2B are brake fluid pressure control.
The brake fluid pressure control device 4 is connected to the brake fluid pressure control device 4.
Rake hydraulic pressure is applied to each wheel brake B_FL, B_FR, B_RL, B_RRTo
It works. In the brake fluid pressure control device 4,
Each wheel brake is controlled by the control unit 5.
B_FL, B_FR, B_RL, B_RRBrake fluid pressure acting on
The control unit 5 includes each wheel W
_FL, W_FR, W_RL, W_RRCar that detects each wheel speed
Wheel speed detector 6_FL, 6_FR, 6_RL, 6_RR, Steering wheel
Steering angle detecting means for detecting a steering angle δ operated by a handle H
7. Yaw rate detection means for detecting the yaw rate γ of the vehicle
8, and lateral acceleration detection for detecting the lateral acceleration AY of the vehicle
The detection values of the output means 9 are respectively input. Referring to FIG. 2, a control unit 5 controls a vehicle speed.
Degree detecting means 10, slip rate calculating means 11, tire
Characteristic setting means 12, wheel slip angle calculating means 13,
The friction coefficient estimating means 14 determines a turning behavior state of the vehicle.
Determining means 15 and each wheel in the brake fluid pressure control device 4
Brake B_FL, B_FR, B_RL, B_RRCalculate the brake pressure of
Brake pressure calculating means 16. In the vehicle speed detecting means 10, the wheel of each wheel
Four wheel speed detectors 6 for individually detecting speeds
_FL, 6_FR, 6_RL, 6_RRBased on the detected value of
The slip ratio calculation means 11 obtains the vehicle speed
The vehicle speed V calculated in step 10 and the wheel speeds
Detector 6_FL, 6_FR, 6_RL, 6_RREach car based on the detected value
The slip ratio λ for each wheel is calculated. The tire characteristic setting means 12 includes a tag for each wheel.
Tire characteristics for each ear are set in advance based on actual driving data
As shown in FIG. 3, the slip angle α of the wheel
Angle showing the relationship between cornering force and CF
-Cornering force characteristics, slip ratio λ and
Slip showing the relationship of the knocking force reduction rate RCF
rate-Cornering force reduction rate characteristics and slip ratio λ
And the slip ratio indicating the relationship between the braking and driving force FX
The power characteristics and the road surface estimated by the friction coefficient estimating means 14
Depending on the friction coefficient μ of the left and right front wheels and the left and right rear wheels.
It is set separately in advance. That is, tire characteristics
The setting means 12 calculates the estimated value obtained by the friction coefficient estimating means 14.
Slip angle-cornering force according to friction coefficient μ
Characteristics, sliprate−Cornering force reduction rate
For compensating the slipperiness and braking / driving force characteristics
It has a function. The wheel slip angle calculating means 13 is provided for turning the vehicle.
In order to increase the control accuracy in performing the rotational motion control,
The front wheel slip angle αF based on the side slip angle β of the vehicle body and
The rear wheel slip angle αR is calculated.
Steering angle δ detected at step 7, detected by yaw rate detecting means 8
Is detected by the lateral acceleration detecting means 9
Vehicle acceleration detected by lateral acceleration AY and vehicle speed detection means 10
Speed V, each wheel calculated by the slip ratio calculation means 11
And the tire characteristic setting means 12.
The front wheel slip angle αF and the
And the rear wheel slip angle αR is calculated by the wheel slip angle calculating means 13.
Is calculated by Obtained by the wheel slip angle calculation means 13
The front wheel slip angle αF and the rear wheel slip angle αR
It is input to the disconnecting means 15 and the determining means 15 determines that the front wheel slips.
Vehicle turning based on the angle αF and the rear wheel slip angle αR
A determination of the motion state is made. In FIG. 4, wheel slip angle calculating means 1
3 is a running state detection unit 17, a lateral acceleration estimation unit 18,
First side slip angle calculation unit 19 and second side slip angle calculation unit 20
And a selector 21 and a slip angle calculator 22. The tire set by the tire characteristic setting means 12
Of slip angle-cornering force characteristics
And slip rate-cornering force reduction rate characteristics
Based on the estimated lateral acceleration A
YE is estimated. That is, the lateral acceleration estimation unit 18
When the tire characteristic setting means 12 is connected,
Slip rate λ calculated by the slip rate calculating means 11, and
Front wheel slip angle αF calculated by slip angle calculation unit 22
And the rear wheel slip angle αR are input, and the left and right front
Sum of four wheels (CF × RCF) for each wheel and left and right rear wheels
Based on the estimated lateral acceleration A
YE will be obtained. In the above operation (CF × RCF)
Based on the slip rate-cornering force reduction rate characteristics.
Cornering force reduction rate RCF
Multiplied by Gforce CF for vehicle motion control
Changes in the slip ratio λ
The ring force CF is corrected. The estimated lateral acceleration obtained by the lateral acceleration estimating unit 18
The degree AYE is input to the first side slip angle calculator 19. This
The first side slip angle calculation unit 19 includes the estimated lateral acceleration AY
In addition to E, the vehicle speed detected by the vehicle speed detecting means 10
Degree V and yaw rate detected by yaw rate detecting means 8
Is a non-linear four-wheel vehicle motion model
Is calculated as the first side slip angle β1 based on the
The output calculation is executed by the first side slip angle calculation unit 19. Here, a "non-linear four-wheel vehicle motion model"
Are the left and right front wheels and the left and right rear wheels
With respect to the slip angle without assuming that
The cornering force of each wheel changes nonlinearly
It is a motion model that reflects various tire characteristics. Based on a basic linear motorcycle motion model
According to the differential equation, the differential value of the sideslip angle is ｛(lateral acceleration
Degree / vehicle speed)-Yaw rate
The lateral acceleration is assumed to be the estimated lateral acceleration AYE, and the vehicle speed is
The vehicle speed V detected by the body speed detecting means 10 is referred to as yaw.
Yaw rate detected by yaw rate detecting means 8
By setting γ, dβ1 / dt = (AYE / V) −γ (1) The differential value (dβ1 / dt) of the first side slip angle β1 is
can get. In addition, the differential value (dβ1 / dt) is integrated.
As a result, the first side slip angle β1 becomes β1 = ∫ ｛(AYE / V) −γ｝ dt + β1₀…… (2) As a result, the first side slip angle calculation unit 19 obtains
You. Thus, in the above integral equation, β1₀Is the first sideslip angle
is the initial value of β1 and is input from the second sideslip angle calculation unit 20
Is done. By the way, the above-mentioned nonlinear four-wheel vehicle motion model
The first side slip angle β1 obtained on the basis of the
Suitable for the sideslip angle when the amount of sideslip is relatively large
However, when the vehicle is traveling straight at low speed,
When the amount of sideslip is relatively small, the first sideslip angle β1
The error due to accumulation of noise during the integration operation is relatively large
And the vehicle is running at a low speed in a straight line.
Using the slip angle β1, the front wheel slip angle αF and the rear wheel slip
It is not appropriate to obtain the tip angle αR. Therefore, the linear
The side slip angle of the vehicle body is set to the second side slip based on the wheel vehicle motion model.
The calculation to obtain the inclination angle β2 is actually performed by the second side slip angle calculation unit 20.
Is performed. Here, "linear two-wheel vehicle motion model"
Means that the left and right front wheels have equal cornering forces, and
Left and right rear wheels assume equal cornering forces
The front and rear cornering for
This is a motion model in which the source changes linearly. FIG. 5 shows a linear two-wheel vehicle motion model.
The left and right front wheel cornering force CFF
Equal, left and right rear wheel cornering force CFR
Using the dynamic equation in the horizontal direction, where
In FIG. 5, the slip angle αF of the front wheel and the rear wheel
The slip angle αR and the side slip angle β of the vehicle body are positive in the counterclockwise direction.
It is expressed as Thus, if the mass of the vehicle is M and the front wheel
CFF for cornering force, cornering for rear wheel
Where CFR is M ・ AY = CFF + CFR …… (3) Can be expressed as Also Cornering Force C
F is the front wheel slip angle αF and the rear wheel slip angle αR
When it is in a minute range, it is linear as shown in FIG.
Therefore, the cornering power of the front wheels is
When the nulling power is CPR, CFF = CPF × αF (4) CFR = CPR × αR (5) It is. The front wheel slip angle αF and the rear wheel slip angle αF
The lip angle αR is the distance LF from the vehicle center of gravity to the front wheel, the vehicle
Distance LR from center of gravity to rear wheel, vehicle speed V, side of vehicle
Slip angle β, yaw rate γ and actual steering angle of front wheelsδwFor
And can be expressed as follows: [0025] αF = β + (LF / V) × γ−δw (6) αR = β− (LR / V) × γ (7) Here, the actual steering angle δw of the front wheel is detected by the steering angle detecting means 7.
Is divided by the gear ratio of the steering system.
Can be obtained. The above equations (4) to (7) are substituted into equation (3).
Then             M × AY = CPF × {β + (LF / V) × γ−δw}                       + CPR × {β- (LR / V) × γ} (8) Holds, and rearranging this equation (8) with respect to β,   β = {M / (CPF + CPR)} × AY       − {(CPF × LF−CPR × LR) / (CPF + CPR)} × γ / V       + {CPF / (CPF + CPR)} × δw (9) Can be obtained. Thus, CPF, CPR, LF, L
Since R and M are constant values specific to the vehicle, the above equation (9) is used.
Can be rewritten as follows. [0027] β = C1 × AY−C2 × γ / V + C3 × δw (10) The second sideslip angle calculation unit 20 performs the calculation based on the above equation (10).
Which is detected by the vehicle speed detecting means 10.
Vehicle speed V, yaw rate detected by yaw rate detecting means 8
Late γ, lateral acceleration A detected by lateral acceleration detecting means 9
Y and the steering angle δ detected by the steering angle detection means 7 are the second horizontal
The slip angle is input to the slip angle calculator 20 and the second side slip angle calculator 20
Is the side slip angle β obtained by the calculation based on the above equation (10).
Output as the side slip angle β2. The first side slip angle calculated by the first side slip angle calculator 19
Calculated by the sideslip angle β1 and the second sideslip angle calculation unit 20
The selected second side slip angle β2 is selectively selected by the selection unit 21.
And input to the slip angle calculation unit 22.
Alternatively, the alternative selection by the selection unit 21 is performed by the traveling state detection unit.
17 is switched. The traveling state detecting section 17 is a vehicle speed detecting means.
The vehicle speed V detected at 10 and the yaw rate detection means 8
Detected yaw rate γ, detected by lateral acceleration detecting means 9
Lateral acceleration AY detected by the steering angle detecting means 7
It detects the running state of the vehicle based on the steering angle δ.
For example, whether all of the following conditions are satisfied
Judge. V <10 km / h -3 (deg) <δ <+3 (deg) −0.1 (G) <AY <+0.1 (G) −1.0 (deg / s) <γ <+1.0 (deg / s) When all of the above conditions are satisfied, the traveling state detection unit 17
Indicates that the vehicle is in a low-speed running state in which
The second slip angle β2 calculated by the inclination angle calculation unit 20 is selected by the selection unit 2
1 is given to the selection unit 21,
If any one of the conditions is not satisfied, the first horizontal
Select the first side slip angle β1 calculated by the slip angle calculation unit 19
A signal to be selected by the section 21 is given to the selection section 21. In the slip angle calculation unit 22, the selection unit 21
First side slip angle β1 or second side angle selected and input
The slip angle β2 and the vehicle body detected by the vehicle speed detecting means 10
Speed V, yaw rate detected by yaw rate detecting means 8
γ and the steering angle δ detected by the steering angle detecting means 7 are used.
And the front wheel slip angle α based on the above equations (6) and (7).
Calculation of F and rear wheel slip angle αR is performed. sand
That is, the slip angle calculator 22 calculates the slip angle based on the equations (6) and (7).
The front wheel slip angle αF and the rear wheel slip angle αR
Calculated by the slip angle calculator 22.
Front wheel slip angle αF and rear wheel slip angle αR
For calculating the estimated lateral acceleration AYE in the acceleration estimating unit 18
Is input to the lateral acceleration estimating unit 18 and the determining means
15 and the coefficient of friction estimation means 14. In FIG. 7, the friction coefficient estimating means 14
First deviation calculating section 23 and vehicle body yaw moment estimating section 24
, A differentiating circuit 25, a second deviation calculating unit 26,
And an estimation operation unit 28. The first deviation calculator 23 calculates a wheel slip angle.
The estimation obtained by the lateral acceleration estimator 18 in the calculating means 13
The constant lateral acceleration AYE and the lateral acceleration detected by the lateral acceleration detecting means 9
The difference (AYE-AY) from the lateral acceleration AY is calculated. On the other hand, the second deviation calculator 26 calculates the tire characteristics.
Calculation of tire characteristics and slip rate set by the property setting means 12
Wheel slip ratio and wheel calculated by output means 11
Calculated by the slip angle calculator 22 of the slip angle calculator 13
Based on the front and rear wheel slip angles
And the vehicle body yaw moment estimated by the
Estimated yaw rate change speed (dγ / dt) E
-Differentiate the yaw rate γ detected by the rate detecting means 8
Yaw rate change speed dγ / d obtained by differentiating circuit 25
t (dγ / dt) E−dγ / dt} is calculated.
You. In FIG. 8, if the vehicle is making a turning motion,
Left and right front wheels and left and right rear wheels
Are CFFL, CFFR, CFRL, CFRR,
The braking / driving forces of the left and right front wheels and the left and right rear wheels are FXFL,
FXFR, FXRL, FXRR, left and right front wheels and
When the tread between the left and right rear wheels is T,
In the vehicle body yaw moment.
The estimated yaw rate change speed (dγ / dt) E is as follows:
It is estimated based on the calculation. [0036] (Equation 1) In the above equation (11), CFFL, CFF
R, CFRL and CFRR are transmitted to the tire characteristic setting means 12.
Set slip angle-cornering force characteristics
And slip rate-cornering force reduction rate characteristics
Based on the left and right front wheels and the left and right rear wheels (CF ×
RCF), and is obtained by executing
XFL, FXFR, FXRL, FXRR are tire characteristics
Slip ratio set in setting means 12-braking / driving force
It is obtained for each of the left and right front wheels and the left and right rear wheels based on the characteristics.
Things. In order to calculate the above equation (11), the vehicle
The body yaw moment estimating unit 24 includes a tire characteristic setting unit.
Tire characteristics and slip ratio calculation means 11 set in 12
Calculation of slip ratio λ and wheel slip angle calculated by
The front wheel calculated by the slip angle calculation unit 22 of the means 13
And the rear wheel slip angles αF and αR are input. The lateral acceleration estimating section 18 estimates
Lateral acceleration AYE and body yaw moment estimating unit 2
4 is the yaw rate change speed (dγ / dt) E estimated
Corresponds to the tire characteristics set by the tire characteristic setting means 12.
It is based on Therefore, the actual road surface friction coefficient μ
Is the lateral acceleration AYE and the yaw rate change speed (dγ /
dt) Variation from the friction coefficient μ of the tire characteristics used in the calculation of E
When the lateral acceleration is detected by the lateral acceleration detecting means 9,
The change in the friction coefficient μ between the speed AY and the estimated lateral acceleration AYE
The deviation corresponding to the compound is generated, and the yaw rate is detected.
The differential value (dγ / d) of the yaw rate γ detected by the means 8
t) and estimated by the vehicle body yaw moment estimation unit 24
Between the yaw rate change rate and the friction coefficient μ
Deviations should occur. These two deviations,
That is, the estimated deviation of the lateral acceleration and the yaw rate change rate (Y
-Late traits) are used when the coefficient of friction on the road surface is relatively large.
And a relatively small case. So
Here, the detected lateral acceleration AY and estimated lateral acceleration AYE
Calculated by the first deviation calculator 23 for calculating the deviation of
The differential value (dγ / dt) and estimate of the detected yaw rate γ
Calculate the deviation of the constant yaw rate change speed (dγ / dt) E
The larger the value calculated by the second deviation calculator 26,
When the influence of the change in the friction coefficient μ
The high select unit 2 determines that the deviation corresponds to the
7 and the deviation selected by the high selection section 27.
Corresponds to the deviation of the coefficient of friction μ
The calculation unit 28 estimates the friction coefficient μ. That is, in the estimation calculating section 28, the friction coefficient μ
The initial value of is set to “1” and corresponds to the change in the friction coefficient μ.
For the calculated deviation of the first or second deviation calculators 23 and 26,
The corresponding change in friction coefficient was obtained in the previous processing loop.
By adding or subtracting from the friction coefficient μ
The friction coefficient μ in the processing loop will be estimated. In FIG. 9, the judgment means 15 includes left and right wheels.
Vehicle based on a two-wheel model with the same slip angle
To determine the turning behavior of the vehicle
Limit value setting unit 29 and front wheel slip angle limit value calculation unit 30
, A rear wheel slip angle limit value calculation unit 31, first and second
It includes two comparators 32 and 33 and a determination unit 34. The vehicle body skid angle limit value setting unit 29 includes a vehicle
The vehicle speed V detected by the body speed detecting means 10 and the friction
The friction coefficient μ of the road surface estimated by the number estimating means 14 is input.
Is done. Thus, the vehicle body skid angle limit value setting unit 29 includes:
As shown in FIG. 10, as the vehicle speed V increases,
And increase as the friction coefficient μ increases.
And the skid angle limit value β_LMTIs the vehicle speed V and the friction coefficient
The map determined according to μ is set in advance, and the vehicle speed
Side slip angle limit value β depending on degree V and friction coefficient μ_LMTBut
It is set by the vehicle body skid angle limit value setting unit 29. The front wheel slip angle limit value calculation unit 30 is a
Side slip angle limit set by side slip angle limit value setting unit 29
Value β_LMTIs calculated by the above equation (6), that is, ｛αF = β +
(LF / V) × γ−δw｝
Slip angle limit value αF_LMTIs calculated. The rear wheel slip angle limit value calculation unit 31 is a
Side slip angle limit set by side slip angle limit value setting unit 29
Value β_LMTIs calculated by the above equation (7), that is, ｛αR = β−
(LR / V) × γ｝, the rear wheel slip
Angle limit αR_LMTIs calculated. The non-inverting input terminal of the first comparator 32 has a car
The front wheel slip angle α obtained by the wheel slip angle calculation means 13
F is input to the inverting input terminal of the first comparator 32.
The front wheel slip calculated by the wheel slip angle limit value calculation unit 30
Angle limit αF_LMTIs entered. The non-inverting input terminal of the second comparator 33
The rear wheel slip angle α obtained by the wheel slip angle calculation means 13
R is input, and the inverted input terminal of the second comparator 32 is
The rear wheel slip calculated by the wheel slip angle limit value calculator 31
Angle limit αR_LMTIs entered. The judgment section 34 includes the first and second comparators 3
2 and 33 are input, and the determination unit 34
And the turning of the vehicle based on the outputs of the second comparators 32 and 33.
The turning behavior state is determined as follows. That is, the judging section 34 calculates the first and second ratios.
When the outputs of the comparators 32 and 33 are both at the high level,
That is, αF> αF_LMT, ΑR> αR_LMTWhen the vehicle is
It is determined that the vehicle is out of the course, and the output of the first comparator 32 is determined.
When the power is high and the output of the second comparator 33 is
At low level, that is, αF> αF_LMT, ΑR ≦ α
R_LMTThe vehicle is understeer
And the output of the first comparator 32 is at the low level.
When the output of the second comparator 33 is at a high level,
That is, αF ≦ αF_LMT, ΑR> αR_LMTWhen the vehicle
Determined that the vehicle was in a state of oversteer,
And the outputs of the second comparators 32 and 33 are both low level.
That is, αF ≦ αF_LMT, ΑR ≦ αR_LMTWhen
Is determined to be in a normal turning state. Referring again to FIG.
The judgment result of the two turning behavior states, that is, the judgment unit 34
The judgment result and the front wheel and rear wheel
Before being calculated by the tip angle limit value calculation units 30 and 31, respectively.
Wheel and rear wheel slip angle limit value αF_LMT, ΑR_LMTWhen
Is input to the brake pressure calculating means 16. This break
In addition to the input from the determination means 15,
The steering angle δ obtained by the steering angle detecting means 7 and the yaw rate detection
The yaw rate γ detected by the means 8 and the vehicle speed detecting means 1
The vehicle speed V detected at 0 and the wheel slip angle
Front wheel slip angle αF and rear wheel slip angle obtained by
Since the lip angle αR has been input,
If it is determined that the vehicle is in a normal turning state, the detected yaw
Γ, the steering angle δ, and the vehicle speed V
Each wheel brake so that the difference from the range yaw rate is small
B_FL, B_FR, B_RL, B_RRBrake pressure is the brake pressure
The brake fluid pressure control device 4
Each wheel shake based on the calculation result of the
B_FL, B_FR, B_RL, B_RRControl the brake fluid pressure
You. However, if the vehicle is out of course,
In a state of a little or oversteer
When the determination means 15 determines that
The calculating means 16 calculates the detected yaw rate γ as the standard yaw rate.
Stop the control calculation to bring the vehicle closer to
And the rear wheel slip angle αR is the front wheel and rear wheel slip angle
Limit value αF_LMT, ΑR_LMTFor each wheel block,
Rake B_FL,B_FR, B_RL, B_RRCalculate the brake pressure of
The brake fluid pressure control device 4 is operated. Next, the operation of this embodiment will be described.
In the wheel slip angle calculation means 13,
It is detected by the running state detecting unit 17 that the vehicle is in the straight running state.
Is calculated by the second side slip angle calculator 20.
The side slip angle β of the vehicle body is calculated based on the second side slip angle β2.
It is. Moreover, the second side slip angle β2 is determined by the vehicle speed V, the yaw
Linear by the detected values of the unit γ, the lateral acceleration AY and the steering angle δ
Calculated based on the two-wheel vehicle motion model
Running at low speed because it is not integrated.
State, the lateral acceleration V, the yaw rate
Even if the detected values of γ and the vehicle speed V are small,
Sum noise (mounting error noise) and running noise accumulate
The vehicle body skids based on the second skid angle β2.
The angle β can be calculated with high accuracy. On the other hand, if the vehicle is in a straight running low speed state,
Other than the first side slip angle calculated by the first side slip angle calculation unit 19.
The side slip angle β of the vehicle body is calculated based on the side slip angle β1.
Is used to calculate the first side slip angle β.
Body speed V, yaw rate γ, and estimated lateral acceleration AYE
That is, the detected values of the vehicle speed V and the yaw rate γ are relatively large.
And the ratio of the noise magnitude to the detected value
Is relatively small, and the estimated lateral acceleration AYE is
Tire characteristics set and calculated by slip angle calculator 22
Calculated by the calculated slip angle and slip ratio calculating means 11
Is estimated using the slip rate
It is possible to improve the constant accuracy, and the first side slip angle β1
Gained sideslip based on a non-linear four-wheel vehicle motion model
Is obtained by integrating the differential value dβ / dt of the angle β.
The error accumulation due to noise during the integration
To improve the calculation accuracy of the vehicle's sideslip angle β.
Wear. The body of the vehicle body thus estimated with high accuracy
The side slip angle β is determined by the turning motion of the vehicle and the friction coefficient of the road surface.
As the wheel grip changes as the number changes
This indicates the turning behavior of the vehicle,
The wheel slip angles αF and αR vary with the direction of the front and rear wheels.
The angle between the direction of travel of the front and rear wheels, and the road surface of the front and rear wheels
It changes according to the grip force with respect to. Only
Also the front and rear wheels according to the vehicle speed and the road surface friction coefficient
Wheel slip angle limit value αF_LMT, ΑR_LMTCan know in advance
The side slip angle β of the vehicle body
Front wheel slip angle αF and rear wheel slip calculated based on
Angle αR, front wheel and rear wheel slip angle limit value αF
_LMT, ΑR_LMTBy comparing with the limit value of the vehicle
Turning behavior state, that is, course out state, and unders
Check for tear or oversteer
It is possible to put out. Besides, the front wheel slip angle αF
And the rear wheel slip angle αR, the change in the friction coefficient μ of the road surface
Because it reflects the turning behavior of the vehicle,
Accurate detection can be made by reflecting the friction coefficient μ.
Turning by braking according to detection of accurate turning behavior
Time behavior control can be performed. The embodiment of the present invention has been described in detail above.
The description is not limited to the above embodiment, but
Various designs without departing from the invention described in the scope
Changes can be made. [0054] As described above, according to the present invention, the side of the vehicle body
Based on slip anglehandFront wheel slip angle and rear wheel slip angle
CalculateOn the other hand, the vehicle speed and the road surface friction coefficient
The front wheel slip angle limit and the rear wheel slip angle limit
Values, their limit values and the front and rear wheel slip angles
To compare the turning behavior of the vehicle with the road surface.
Accurate detection can be made by reflecting the friction coefficient.Special
In detecting the turning behavior state, the front wheel slip
The angle exceeds the front wheel slip angle limit and the rear wheel slip angle
When the rear wheel slip angle limit is exceeded, the vehicle
Is judged to be in a slip-out state, and the front wheel slip angle is
The wheel slip angle limit value is exceeded and the rear wheel slip angle is
When the vehicle is below the lip angle limit, the vehicle may understeer.
It is determined that the vehicle is in the taste state, and the front wheel slip angle is
Is less than the lip angle limit value and the rear wheel slip angle is
When the vehicle exceeds the lip angle limit, the vehicle
It is determined that the vehicle is in a slightly tear state, and the front wheel slip angle is
The front wheel slip angle is below the limit value and the rear wheel slip angle is
When the vehicle is below the rear wheel slip angle limit, the vehicle
Can be determined to be in a turning state.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a drive system and a brake system of a vehicle. FIG. 2 is a block diagram illustrating a configuration of a control unit. FIG. 3 is a diagram showing tire characteristics set by tire characteristic setting means. FIG. 4 is a block diagram showing a configuration of a wheel slip angle calculating means in the control unit. FIG. 5 is a diagram showing the balance of lateral forces in a linear two-wheel vehicle motion model. FIG. 6 is a diagram showing tire characteristics used in a linear two-wheel vehicle motion model. FIG. 7 is a block diagram showing a configuration of friction coefficient estimating means. FIG. 8 is a diagram showing a cornering force and a vehicle body moment generated by braking / driving force during a turning motion of the vehicle. FIG. 9 is a block diagram showing a configuration of a means for determining a turning behavior of the vehicle. FIG. 10 is a view showing a setting map according to a vehicle speed and a friction coefficient of a limit value of a side slip angle of the vehicle body. [Description of Signs] 8 ··· Yaw rate detecting means 10 ··· Body speed detecting means 13 ··· Wheel slip angle calculating means 14 ··· Friction coefficient estimating means 15 ··· Judging means αF · Front wheel slip corner αR ··· rear wheel slip angle αF _LMT ·· front wheel slip angle limit value αR _LMT ·· rear wheel slip angle limit value β ···· vehicle slip angle μ ···· road surface friction coefficient V ···・ Vehicle speed

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-8-164833 (JP, A) JP-A-9-240458 (JP, A) JP-A-6-336172 (JP, A) JP-A-4- 362474 (JP, A) JP-A-5-155323 (JP, A) JP-A-2-70561 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60T 8/58

Claims (1)

(57) [Claim 1] A vehicle speed detecting means (10) for detecting a vehicle speed; a yaw rate detecting means (8) for detecting a yaw rate; and a vehicle slip angle (β). A wheel slip angle calculating means (13) for calculating a front wheel slip angle (αF ) and a rear wheel slip angle (αR) , and a road surface friction coefficient
Friction coefficient estimating means (14 ) for estimating (μ) ; front and rear wheel slip angles (αF, αR) obtained by the wheel slip angle calculating means (13); and vehicle body speed detecting means (10). the front wheel slip angle limit value determined based on the vehicle speed (V) and the coefficient of friction which is estimated the friction coefficient estimation means (14) to be detected (mu) (.alpha.F _LMT) and a rear wheel slip angle threshold value ([alpha] R _LMT ) and compared by determining means for determining the turning behavior state of the vehicle (15) of; equipped with, said determining means (15), the front wheel slip angle (.alpha.F) front wheels
Slip angle limit value (αF _LMT ) exceeded and rear wheel slip
Angle (αR) exceeds the rear wheel slip angle limit value (αR _LMT )
When the vehicle is out of course,
The front wheel slip angle (αF) is equal to the front wheel slip angle limit value (αF
_LMT ) and the rear wheel slip angle (αR)
When the vehicle angle is below the limit angle (αR _LMT ), the vehicle is under
When the vehicle is in a slightly steer state, the front wheel slip angle (α
F) is equal to or less than the front wheel slip angle limit value (αF _LMT ) and
The rear wheel slip angle (αR) is the rear wheel slip angle limit value (α
R _LMT ) when the vehicle is oversteer
When in the taste state, the front wheel slip angle (αF) is also the front wheel
Slip angle limit (αF _LMT ) or less and rear wheel slip
Is less than the rear wheel slip angle limit (αR _LMT )
If the vehicle is in normal turning when
A turning behavior state detection device for a vehicle, characterized in that each determination is performed.