JPH10329689A - Car body behavior controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a tire from exceeding the limit of the time in turning to suitably control the braking drive force or steering angle. SOLUTION: In this device, a tire use level of each wheel at this point of time is calculated (S300). The tire use level of each wheel is obtained by determining which position of a friction circle of tire the presence state of the tire is situated in, or whether it is within the tire limit or not from a slip rate of present time and an existing slip angle. A steering angle correction quantity of each wheel is successively determined by use of the tire use level of each wheel and a prescribed map. By use of the tire use levels of front or rear lateral wheels, the steering angle correction quantity to each wheel of lateral wheels on the respective sides is determined (S310). Namely, supposing that a rotating moment in the turning of a vehicle evenly acts on the lateral wheels, and the steering angle correction quantity is set so as not to break the balance of the rotating moment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body behavior control device capable of stabilizing a vehicle behavior during a turn, for example.

[0002]

2. Description of the Related Art Conventionally, for example, steering angle control, braking force control, driving force control, and the like are known as techniques for controlling the behavior of a vehicle body while the vehicle is running. Among them, as the steering angle control, for example, 4WS control is known. This steering angle control is, for example, to prevent occurrence of spin or drift at the time of turning, and to advance the vehicle in a desired turning direction as much as possible. This is a technique for controlling the direction of the tire and the like in order to cause the tire to rotate.

As braking force control, a so-called anti-skid control (ABS control) is known. This anti-skid control is a method in which a braking force falls within a predetermined slip rate range in which a high braking force can be exerted. In addition, the wheel cylinder pressure is adjusted to control the rotation speed of the wheels.

[0004] Further, as driving force control, so-called traction control is known. This traction control is to reduce the output of the engine so as to fall within a predetermined slip ratio range in which high driving force can be exhibited during acceleration. The wheel speed is controlled by adjusting the wheel cylinder pressure.

[0005]

However, in the steering angle control, a tire margin which varies depending on the longitudinal force (indicated by a braking force or a driving force) at that time, or a tire which varies according to a slip ratio which is a parameter of the longitudinal force. Since the allowance is not taken into consideration, that is, the control is performed without taking into account the allowance up to the limit at which the tire can exert a sufficient longitudinal force, it is not always sufficient.

In the braking force control and the driving force control, on the other hand, a tire limit, which varies depending on the lateral force of the tire, and a slip angle (an angle between the traveling direction of the vehicle and the tire direction) which is a parameter indicating the lateral force. In this case, the control is performed without considering the tire limit that changes due to the above.

In other words, when lateral force or longitudinal force is simultaneously applied to the tire during turning braking or turning acceleration,
If the mutual control is performed without considering the reduction of the tire margin due to each force, the tire limit is easily exceeded. When the tire limit is exceeded, no more lateral force and no longitudinal force can be generated, so that it is not possible to generate a braking force for the brake operation and a turning force for the steering angle, making control and steering difficult. There is a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is intended to prevent a tire from exceeding a tire limit during turning or the like.
An object of the present invention is to provide a vehicle body behavior control device capable of suitably controlling braking / driving force and steering angle.

[0009]

According to the present invention, the estimating means estimates the slip ratio and the slip angle of each wheel of the vehicle, and the control means calculates the slip ratio and the slip angle of each wheel based on the slip ratio and the slip angle of each wheel. Control the braking force and / or driving force of each wheel.

Here, the slip ratio is defined by the following [Equation 1] during braking and by the following [Equation 2] during driving. Incidentally, by multiplying the slip ratio by 100, it can be shown in%. [Equation 1] (During braking) Slip ratio = (Vehicle speed-Wheel speed) / Vehicle speed [Equation 2] (Driving) Slip ratio = (Vehicle speed-Wheel speed) / Wheel speed The slip angle will be described later. As shown in FIG. 4, the angle between the traveling direction of the tire and the center plane of the tire.

As shown in FIG. 1, during traveling such as turning,
The state of the tire (the state of the force applied to the tire; hereinafter, referred to as a tire use level) can be indicated using a friction circle of the tire. The friction circle of the tire is obtained by taking the slip ratio on the ordinate and the slip angle on the abscissa. The tire usage level is determined by, for example, the slip ratio, the slip angle and the slip angle as shown in the following [Equation 3]. Is the adjacent side of the rectangle,
Using the three-square theorem, it can be obtained from the length of the diagonal line. [Equation 3] Tire usage level = ｛(slip ratio / maximum slip ratio reference value) ² + (slip angle / maximum slip angle reference value) ² ｝ ^1/2 where the maximum slip angle at which lateral force can be generated A certain maximum slip angle reference value (maximum cornering force (CF)
The generated slip angle is, for example, ± 10 deg, and the maximum slip rate reference value (maximum slip force generated slip rate), which is the maximum slip rate at which the longitudinal force can be generated, is, for example, ± 20.
%.

Note that the range of the friction circle of the tire shown in white in FIG. 1 is a range in which the lateral force and the longitudinal force can be generated. 4]. [Equation 4] ｛(Slip ratio / Maximum slip ratio reference value) ² +
(Slip angle / maximum slip angle reference value) ² ｝ ^1/2 <1 In other words, in the present invention, since the tire use level can be determined from the slip ratio and the slip angle, the braking force of each wheel is determined based on the tire use level. Or, it controls the driving force or both (for example, wheel cylinder pressure, engine output, etc.).

More specifically, a brake control for adjusting, for example, a wheel cylinder pressure of each wheel, in consideration of a tire margin of each wheel, so that a tire use level of each wheel falls within a range of a tire friction circle. By controlling an actuator or an engine control actuator, for example, by setting a target slip rate, which is a target slip rate according to the tire usage level, it is possible to suitably control the braking state of the vehicle.

According to the second aspect of the present invention, the estimation means
The slip ratio and the slip angle of each wheel of the vehicle are estimated, and the control means controls the slip angle of each wheel based on the slip ratio and the slip angle of each wheel. That is, in the present invention, since the tire use level can be determined from the slip ratio and the slip angle, the slip angle of each wheel is controlled based on the tire use level.

More specifically, the steering angle of each wheel, for example, the steering angle of each wheel is adjusted so that the tire usage level of each wheel falls within the range of the friction circle of the tire in consideration of the tire margin of each wheel. By controlling the steering angle control actuator, for example, by correcting the target steering angle amount which is the control target value according to the tire usage level, the turning state of the vehicle can be suitably controlled.

According to the third aspect of the present invention, the estimation means
The slip ratio and the slip angle of each wheel of the vehicle are estimated, and the control unit controls the braking force and / or the driving force of each wheel and the slip angle based on the slip ratio and the slip angle of each wheel. In other words, the present invention has the configuration according to the first and second aspects, and since the tire use level can be determined from the slip rate and the slip angle, the slip rate and slip of each wheel are determined based on the tire use level. The angle is controlled together.

More specifically, for example, a brake control actuator, a driving force control actuator, etc., for each wheel, in consideration of the tire margin of each wheel, so that the tire usage level of each wheel falls within the range of the friction circle of the tire. By controlling the steering angle control actuator, the turning braking state and the turning drive state of the vehicle can be suitably controlled.

In the invention of claim 4, as the estimating means,
Means for estimating the state of the force applied to the tire can be adopted based on the parallel root of the sum of the square value of the slip ratio and the square value of the slip angle. That is, as described in the first aspect, the state of the force applied to the tire (tire use level) can be obtained by, for example, the above [Equation 3]. That is, when the maximum slip ratio reference value and the maximum slip angle reference value of [Equation 3] are considered as constants, the configuration of the present invention becomes clear.

Thus, the tire use level can be determined by the three-square theorem. According to the fifth aspect of the present invention, the control means is executed at the time of braking or driving.
For example, by controlling the driving force (in this case, the force for reducing the deceleration slip) during braking, it is possible to adjust the balance between the lateral force and the longitudinal force applied to the tire within the tire limit, thereby achieving stable operation. It is possible to perform braking while exhibiting a high braking force.

Further, by controlling the braking force (in this case, the force for reducing the acceleration slip) at the time of driving, the balance between the lateral force and the longitudinal force applied to the tire can be adjusted within the tire limit. Therefore, it is possible to perform acceleration while exhibiting a stable and high driving force.

According to the invention of claim 6, the control means is executed at the time of turning. At the time of turning, by controlling the steering angle, it is possible to adjust the balance between the lateral force and the longitudinal force applied to the tire within the tire limit, so that the vehicle can turn stably in a desired turning direction. .

According to the seventh aspect of the present invention, the control means can be executed at the time of turning braking or turning driving. For example, at the time of turning braking, by controlling the driving force (in this case, the force for reducing the deceleration slip) and the steering angle, it is possible to adjust the balance between the lateral force and the longitudinal force applied to the tire within the tire limit. Therefore, the vehicle can turn in a desired turning direction while exhibiting a stable and high braking force.

Further, by controlling the braking force (in this case, the force for reducing the acceleration slip) and the steering angle during the turning drive, the balance between the lateral force and the longitudinal force applied to the tire within the tire limit is adjusted. Therefore, it is possible to turn stably in a desired turning direction while exhibiting a high driving force.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a vehicle body behavior control device according to the present invention will be described below in detail with reference to the drawings using examples (embodiments). The present embodiment is a vehicle body behavior control device that performs steering angle control and brake control in order to prevent vehicle behavior from becoming unstable when the FF vehicle turns.

A) First, a system configuration of the vehicle body behavior control device according to the present embodiment will be described with reference to FIG. As shown in FIG. 2, the vehicle body behavior control device includes, as sensors for detecting vehicle body behavior, wheels for detecting rotation speeds (wheel speeds) of four wheels 1FR, 1FL, 1RR, 1RL (collectively, 1). Speed sensors 2FR, 2FL, 2RR, 2RL (collectively referred to as 2), and steering angle sensors 3FR, 3FL, 3RR, 3RL (collectively referred to as 3) for detecting a steering angle ACT displacement amount which is an actually bent value of each wheel 1; The steering angle sensor 4 detects a steering angle (steering angle), which is an operation amount of the steering 8, a yaw rate sensor 6 detects a rotational angular velocity (yaw rate) of the vehicle body 9, and detects a lateral acceleration (lateral G) of the vehicle body 9. The horizontal G sensor 7 is provided.

Further, as actuators for controlling the vehicle body behavior, for example, steering angle control actuators 10FR, 10FL, 10RR, 10RL (generally referred to as 10) constituted by hydraulic mechanisms, wheel cylinders 8FR, 8FL, 8RR, 8
A brake control actuator 11 for controlling the braking force by adjusting the pressure of RL (collectively 8), an engine control actuator 12 for controlling the output of the engine 13, and the like are provided.

An electronic control unit (ECU) 14 receives and processes signals from the sensors 1 to 7 and sends control signals necessary for controlling the vehicle body behavior to each of the actuators 1.
0 to 12 to control the behavior of the vehicle body. b) Next, control processing of the vehicle body behavior device having the above-described configuration will be described.

First, the steering angle control will be described with reference to the flowchart of FIG. In step 100 of FIG. 3 (hereinafter, step is referred to as S), detection signals from the sensors 1 to 7 are input, and respective detection values are obtained. Specifically, the wheel speed of each wheel 1 is determined based on the signal from each wheel speed sensor 2, the steering angle ACT displacement amount of each wheel 1 is determined based on the signal from each steering angle sensor 3, and the steering angle is calculated. The steering angle is determined based on the signal from the sensor 4, the yaw rate of the vehicle body 9 is determined based on the signal from the yaw rate sensor 6, and the lateral G of the vehicle body 9 is determined based on the signal from the lateral G sensor 7.

At S110, the vehicle speed (vehicle speed) is obtained from the wheel speed. For example, the average value of the wheel speeds is set as the vehicle speed. In subsequent S120, a target yaw rate is calculated based on the following [Equation 5]. The target yaw rate is a control target value relating to the yaw rate of the vehicle body 9 (a target value to be controlled to this value). [Equation 5]

[0030]

(Equation 1)

However, the steering gear ratio, the wheelbase, and the target stability factor are constants. In the following S130, the target lateral G is calculated based on the following [Equation 6].
Is calculated. The target lateral G is a control target value relating to the lateral G of the vehicle body 9. [Equation 6] Target lateral G = Target yaw rate × Vehicle speed At S140, an additional vehicle lateral force is calculated based on the following [Equation 7]. This additional vehicle lateral force is the target lateral G
Is the lateral force to be applied to the vehicle body to Note that the vehicle body lateral force is a force applied in a lateral direction perpendicular to the front-rear direction (vertical direction in the figure) of the vehicle body as shown in FIG. [Equation 7] Additional body lateral force = (target lateral G-lateral G) × vehicle weight In subsequent S150, an additional yaw moment is calculated based on the following [Equation 8]. The additional yaw moment is a yaw moment applied to the vehicle body in order to set the target yaw rate. Note that yaw G is yaw angular acceleration. [Equation 8] Additional yaw moment = (Target yaw G−Yaw G)
× Moment constant In subsequent S160, the front and rear additional lateral force is calculated based on the following [Equation 9] and [Equation 10]. This additional lateral force is
The additional vehicle lateral force is divided into a front wheel and a rear wheel. In this embodiment, each additional lateral force is equally divided into the left and right wheels at the front wheel and the rear wheel. Thereby, the additional lateral force at each wheel, that is, the lateral force to be applied to each wheel is determined. [Equation 9] Front wheel additional lateral force = (Additional vehicle lateral force x distance between center of gravity rear tire + additional yaw moment) / wheel base [Equation 10] Rear wheel additional lateral force = (Additional vehicle lateral force x center of gravity front tire distance-Addition) Yaw moment) / wheel base Note that the distance between the center of gravity and the rear tire and the distance between the center of gravity and the front tire indicate the distance between the straight line connecting the left and right tires and the center of gravity.

In S170, the required SF (side force; lateral force) additional amount = the required CF (corner force) additional amount is calculated based on the following [Equation 11]. The necessary SF additional amount is, as shown in FIG. 4, a component of the additional lateral force applied to the tire in a direction perpendicular to the front-rear direction of the tire. Thereby, the additional lateral force to be applied to each tire in the vertical direction, that is, the necessary SF additional amount is obtained. [Equation 11] Required SF additional amount = Additional lateral force at each wheel / c
os (αi) where αi is the lateral force (additional lateral force) and SF at each wheel.
(The necessary SF addition amount), and αi = steering angle +
This is the steering angle ACT displacement amount.

Here, i indicates the distinction between the wheels. S180 that follows
Then, the slip angle of each wheel is calculated based on the following [Equation 12] and [Equation 13]. As shown in FIG. 4, the slip angle is a slip angle at the present time (current slip angle) between the traveling direction of the vehicle and the front-rear direction of the tire. Here, it is assumed that the current slip angles of the left and right wheels are the same for the front wheels and the rear wheels. [Equation 12] front wheel slip angle = vehicle side slip angle + steering angle /
Steering gear ratio + steering angle ACT displacement / steering gear ratio-yaw rate x center-of-gravity front tire distance / vehicle speed [Equation 13] rear wheel slip angle = body side slip angle + steering angle ACT
Displacement amount / steering gear ratio + yaw rate × center-of-gravity rear tire distance / vehicle speed However, vehicle body skid angle = − (lateral G / vehicle speed) + yaw rate In subsequent S190, the target steering angle amount for each wheel is calculated. The target steering angle amount is a steering angle amount from the current slip angle to a target slip angle (target slip angle).
Is determined using a map such as that shown in

That is, as shown in the graph in which the lateral force (SF) is plotted on the vertical axis and the slip angle is plotted on the horizontal axis, the SF at the current time (current SF) is obtained from the current slip angle. The required SF obtained in the above is added to obtain a target SF, and a target slip angle is obtained from the target SF, and from the difference between the target slip angle and the current slip angle,
This is for obtaining the target steering angle amount.

In the following S200, as will be described in detail later, each wheel steering angle correction amount is calculated. In other words, in all four wheels,
In consideration of the tire limit, a correction value for correcting the steering angle amount is determined so as not to exceed the tire limit. In the following S210, each wheel control steering angle is calculated based on the following [Equation 14]. The respective wheel control steering angle amounts are values corrected by adding the respective wheel steering angle correction amounts calculated in S200 to the respective wheel target steering angle amounts calculated in S190. [Equation 14] Each wheel control steering angle amount = Each wheel target steering angle amount (1 + Each wheel steering angle correction amount) In subsequent S220, in order to displace the steering angle of each tire by each wheel control steering angle amount, A control signal is output to the steering angle control actuator 10 in order to bend the direction 1, and the process is once ended.

Thus, during steering angle control, the direction of the wheels 1 is controlled so as not to exceed the tire limit. Next, the wheel steering angle correction amount calculation processing in S200 will be described based on the flowchart of FIG.

In S300 of FIG. 6, the tire usage level of each wheel at the present time is calculated using the above-described [Equation 1] to [Equation 3]. As described in detail above, each wheel tire use level indicates the current tire state in each wheel from the current slip rate (current slip rate) and the current slip angle in FIG. The position of the tire friction circle, that is, whether the tire is within the tire limit or not is determined.

That is, the range of the friction circle indicates the tire limit, and within the range of the friction circle, the driving force is suitably transmitted to the road surface via the tire and the braking force is effectively reduced. Can demonstrate. In S310, the steering angle correction amount of each wheel is determined using the tire usage level of each wheel, for example, using a map as shown in FIG.

Here, the steering angle correction amount for each wheel of the left and right wheels on each side is obtained using the tire usage level of the front or rear left and right wheels. In other words, the rotational moment when the vehicle turns is considered to act equally on the left and right wheels, and the steering angle correction amount is adjusted so as not to break the balance of the rotational moment, that is, to approach the tire use level of the left and right wheels. Is set.

More specifically, FIG. 7A shows a map for obtaining the steering angle correction amount (coefficient) of the FR wheel, and FIG.
FIG. 7C shows a map for obtaining the wheel steering angle correction amount, and FIG.
FIG. 7D shows a map for obtaining the steering angle correction amount of the R wheel, and FIG. 7D shows a map for obtaining the steering angle correction amount of the RL wheel. Here, the FR wheel shown in FIG. 7A is taken as an example. The method of setting the steering angle correction amount will be described.

In FIG. 7A, for example, assuming that the tire use level of the FR wheel is 100% and the tire use level of the FL wheel is 0%, two planes corresponding to the respective numerical values, The plane intersects at one point (in this case, P1). Therefore, the value on the vertical axis (for example, -0.3) corresponding to the intersection P1 is the steering angle correction amount of the FR wheels in this case. Similarly, if the tire use level of the FR wheel is 10% and the tire use level of the FL wheel is 80%, for example, two planes corresponding to the respective numerical values and a curved plane in the figure are one point ( In this case, they meet at P2). Therefore, the value of the vertical axis (for example, +0.1) corresponding to the intersection P2 is the steering angle correction amount of the FR wheels in this case.

Accordingly, by substituting the steering angle correction amount of each wheel determined in S310 into the above [Equation 14] and correcting the target steering angle amount of each wheel, the accurate steering angle amount to be controlled is obtained. (Control steering angle amount) can be obtained. Next, the brake control will be described based on the flowchart of FIG.

At step 400 in FIG.
7, and the respective detection values are obtained. Specifically, the wheel speed, the steering angle ACT displacement amount, the steering angle, the yaw rate, and the lateral G of each wheel 1 are obtained in the same manner as in S100 of FIG. In S410, the vehicle speed (vehicle speed) is obtained from the wheel speed. For example, the average value of the wheel speeds is set as the vehicle speed.

In the following S420, similarly to S180 in FIG. 3, based on the above [Equation 12] and [Equation 13],
The slip angle of each wheel is calculated from the vehicle body side slip angle, steering angle, steering gear ratio, steering angle ACT displacement, yaw rate, center-of-gravity front (or rear) tire distance, and vehicle speed, separately for the front wheels and the rear wheels. The slip angle is the current slip angle, and the front and rear wheels have the same current slip angle for the left and right wheels.

In S430, the slip ratio (at the time of braking) of each wheel is calculated from the wheel speed and the vehicle speed using the above [Equation 2]. In subsequent S440, a target slip ratio correction amount is calculated, as will be described in detail later. That is, in all of the four wheels, a correction value for setting the following target slip ratio is determined in consideration of the tire limit so as not to exceed the tire limit.

In S450, the target slip ratio of each wheel is calculated based on the following [Equation 15]. Each wheel target slip ratio is a slip ratio to be targeted. [Equation 15] Target slip ratio of each wheel = Reference slip ratio (1+
(Each wheel target slip rate correction amount) However, the reference slip rate is a constant.

At S460, a control signal is output to the brake control actuator (brake control ACT) 11 in order to control the slip ratio of each tire to the target slip ratio, and the present process is ended once. For example, as shown in FIG. 9, in a general anti-skid control, the target slip ratio obtained in this embodiment is used. That is, in order to control the wheel speed of each wheel so as to achieve the target slip ratio indicated by the one-dot chain line in FIG. 9, a control signal for driving the brake control ACT based on changes in the wheel speed and wheel acceleration of each wheel is generated. The brake oil pressure is adjusted by switching to pressure reduction / holding / pressure increase (of wheel cylinder pressure). In the present embodiment, in particular, the target slip ratio is changed according to the tire usage level of each wheel.

Thus, during the brake control, the braking force of the wheels 1 is controlled so as not to exceed the tire limit. Next, the process of calculating the target wheel slip ratio in S440 will be described with reference to the flowchart of FIG.

At S500 in FIG. 10, S30 in FIG.
Similarly to 0, the tire use level of each wheel at the present time is calculated based on the above [Equation 3]. S510 that follows
Then, the target slip ratio correction amount of each wheel is determined using the tire usage level of each wheel, for example, using a map as shown in FIG.

Here, the target slip rate correction amount for each of the front and rear wheels on each side is determined using the tire usage levels of the right and left front and rear wheels. That is, when the brake is applied, the target slip ratio correction amount is set so as not to lose the balance of the braking moment at the time of braking, that is, to approach the tire usage levels of the front and rear wheels on each side.

More specifically, FIG. 11 (a) shows a map for obtaining the target slip ratio correction amount (coefficient) for the FR wheel, and FIG.
1 (b) shows a map for obtaining a target slip ratio correction amount for the FL wheel, FIG. 11 (c) shows a map for obtaining a target slip ratio correction amount for the RR wheel, and FIG. 11 (d) shows a target slip ratio for the RL wheel. A map for calculating the rate correction amount is shown. The method for setting the target slip rate correction amount is shown in FIG. 7 and FIG.
Since the method is the same as that described in FIG. 10, its description is omitted here.

Therefore, the target slip ratio of each wheel can be obtained by substituting the target slip ratio correction amount of each wheel obtained in S510 into the above [Equation 14]. Like this
In the present embodiment, when steering angle control is performed, a tire use level is obtained using the current slip ratio and the current slip angle, and a steering angle correction amount is obtained using the tire use level,
Since the control steering angle amount, which is a control amount when performing the steering angle control using the steering angle correction amount, is determined and the steering angle of each wheel is controlled, the steering angle control of each wheel within the tire limit is performed. Can be performed.

In other words, when lateral force or longitudinal force is simultaneously applied to the tires during turning braking, the steering angle control is performed in consideration of the reduction of the tire margin due to each force. Force can always be ensured, so that control and steering can be suitably performed.

In this embodiment, when performing the brake control, the tire use level is obtained by using the current slip ratio and the current slip angle, and the target slip ratio correction amount is obtained by using the tire use level. The target slip ratio, which is a control amount when anti-skid control is performed using the target slip ratio correction amount, is determined, and the wheel cylinder pressure (and, consequently, the wheel speed) of each wheel is controlled. The brake control of each wheel can be performed at the same time.

In other words, when a lateral force or a front-rear force is simultaneously applied to the tires at the time of turning braking, the brake control is performed in consideration of the reduction of the tire margin due to each force, so that a sufficient braking force is always secured. Can be, so
Control and steering can be suitably performed. <Experimental Example> Next, an experimental example will be described.

This experiment was carried out for a conventional vehicle that performs steering angle control and brake control (ABS control) without considering the tire margin, and a vehicle that performs steering angle control and brake control that considers the tire margin of the above-described embodiment. The turning braking was actually performed while traveling along a predetermined reference circle using

Then, the braking longitudinal acceleration in that case and the yaw rate change amount one second after the braking was started at each braking longitudinal acceleration were measured. FIG. 12 shows the result.
As is apparent from FIG. 12, at the time of turning braking, the vehicle normally exhibits an oversteer (rolling inward in the turn) behavior in the low braking G region and an understeer (swelling outward in the turning) behavior in the high braking G region. Show.

In the low braking G range, the load shift to the front wheels easily causes an oversteer behavior, and in this case, the rear wheel has an excessively large slip angle, which tends to cause a spin tendency. Therefore, when the control at the time of turning (moment control) is performed by the lateral force and the braking force without considering the tire margin as in the related art,
A load is applied to tires that cannot afford, and oversteer cannot be sufficiently suppressed.

In the high braking G region, the front wheel reaches its limit due to an increase in the front wheel braking force, and no lateral force can be generated, resulting in understeer behavior. Here, therefore, when the moment control is performed by the lateral force and the braking force without considering the tire margin as in the related art, a load is applied to the tire having no margin, and the moment can be sufficiently generated. And understeer cannot be reduced.

On the other hand, in the case of the present embodiment, the lateral force is taken into consideration in consideration of the tire allowance of each wheel. By distributing the longitudinal force, the forces of the four tires can be used in a well-balanced manner, and the control limit of the vehicle behavior can be raised. still,
It is needless to say that the present invention is not limited to the above embodiments, and can be implemented in various modes without departing from the technical scope of the present invention.

(1) For example, in the above-described embodiment, the case of turning braking is taken as an example, but the present invention can be applied to turning driving. During the turning drive, the brake hydraulic pressure may be controlled by, for example, performing traction control so that the desired target slip ratio is obtained within the range of the tire limit of each wheel.

(2) In the above-described embodiment, both the steering angle control and the brake control are performed. However, performing either one of the controls has an effect corresponding to the control. (3) The vehicle to which the steering angle control of the present embodiment can be applied includes:
For example, the following vehicles are mentioned.

A vehicle in which the relationship between the steering angle and the actual steering angle of the front wheels, for example, can be changed (for example, a vehicle in which the steering is operated by an electric signal). The left and right wheels are mechanically connected like a normal steering mechanism. It is possible to use one that does not have a mechanical connection.

A vehicle having a mechanism for steering the rear wheels and capable of changing the relationship between the steering angle and the actual steering angle of the rear wheels (for example, a 4WS vehicle). It is possible to use one that has no mechanical connection.

Vehicles Having Both of the Above (4) Vehicles to which the brake control of this embodiment can be applied include, for example, the following vehicles. A vehicle capable of raising or lowering the wheel cylinder pressure of at least one wheel from a pressure predetermined from the master cylinder pressure (for example, A
BS car)

[Brief description of the drawings]

FIG. 1 is a graph showing a friction circle of a tire.

FIG. 2 is a system configuration diagram of the vehicle body behavior control device of the embodiment.

FIG. 3 is a main flowchart of the steering angle control of the embodiment.

FIG. 4 is an explanatory diagram showing a relationship between forces applied to a tire of an example.

FIG. 5 is a graph illustrating a relationship between a slip lateral force and a slip angle for obtaining a target steering angle amount according to the embodiment.

FIG. 6 is a flowchart illustrating a steering angle correction amount calculation process according to the embodiment;

FIG. 7 is an explanatory diagram showing a map for setting a steering angle correction amount of each wheel according to the embodiment.

FIG. 8 is a main flowchart of brake control according to the embodiment.

FIG. 9 is an explanatory diagram illustrating an operation of the brake control actuator according to the embodiment.

FIG. 10 is a flowchart illustrating a process of calculating a target slip ratio correction amount according to the embodiment.

FIG. 11 is an explanatory diagram showing a map for setting a target slip ratio correction amount for each wheel according to the embodiment.

FIG. 12 is a graph showing experimental results.

[Explanation of symbols]

1FR, 1FL, 1RR, 1RL, 1 ... Wheel 2FR, 2FL, 2RR, 2RL, 2 ... Wheel speed sensor 3FR, 3FL, 3RR, 3RL, 3 ... Steering angle sensor 4 ... Steering angle sensor 6 ... Yaw rate sensor 7 ... Lateral G Sensor 8FR, 8FL, 8RR, 8RL, 8 ... Wheel cylinder 10FR, 10FL, 10RR, 10RL, 10 ... Steering angle control actuator 11 ... Brake control actuator (Brake control AC)
T) 12: Engine control actuator 14: Electronic control unit (ECU)

Claims (7)

[Claims] An estimating means for estimating a slip rate and a slip angle of each wheel of a vehicle, and a braking force or a driving force or a driving force of each wheel based on the slip rate and a slip angle of each wheel estimated by the estimating means. A vehicle behavior control device, comprising: control means for controlling both of them. 2. Estimating means for estimating a slip rate and a slip angle of each wheel of a vehicle, and controlling to control a slip angle of each wheel based on a slip rate and a slip angle of each wheel estimated by the estimating means. Means, and a vehicle body behavior control device, comprising: 3. Estimating means for estimating a slip rate and a slip angle of each wheel of a vehicle; and a braking force or a driving force or a driving force of each wheel based on the slip rate and a slip angle of each wheel estimated by the estimating means. Control means for controlling both of them and a slip angle; 4. The system according to claim 1, wherein the estimating unit estimates a state of a force applied to the tire based on a parallel root of a sum of a square value of a slip ratio and a square value of a slip angle. A vehicle body behavior control device according to any one of claims 1 to 3. 5. The vehicle body behavior control device according to claim 1, wherein said control means is executed during braking or driving. 6. The vehicle body behavior control device according to claim 2, wherein said control means is executed during a turn. 7. The vehicle body behavior control device according to claim 3, wherein the control unit is executed at the time of turning braking or turning driving.