JP3267137B2 - Vehicle behavior control 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 behavior control device for suppressing and reducing undesirable behaviors such as drift-out and spin during turning of a vehicle such as an automobile.

[0002]

2. Description of the Related Art As one of devices for controlling the behavior of a vehicle such as an automobile at the time of turning, for example, JP-A-2-1097
No. 11, the slip angle β of the vehicle body
Conventionally, a behavior control device that estimates the turning behavior of a vehicle based on the linear sum of the slip angular velocity βd of the vehicle body and controls the roll stiffness of the vehicle when spin is estimated, thereby suppressing oversteer and stabilizing the turning behavior. More known.

According to such a behavior control device, when the spin is estimated, the roll rigidity of the vehicle is controlled.
It is possible to stabilize the behavior during turning compared to a conventional general vehicle in which the turning behavior is not estimated and the roll rigidity is not controlled, thereby preventing the occurrence of undesirable turning behavior such as spin of the vehicle. can do.

[0004]

However, depending on the running state of the vehicle, drift-out may occur simultaneously in addition to spin. For example, the slip angle of the vehicle body is excessive and the vehicle is in a spin state at this point, but the turning trajectory of the vehicle is outside the target trajectory, and at this point the vehicle is also in a drift-out state. May occur. In the conventional behavior control device described in the above publication, the turning behavior of the vehicle is estimated based on the linear sum of the slip angle of the vehicle body and the slip angular velocity of the vehicle body. We cannot cope appropriately.

The present invention has been made in view of the above-mentioned problems in the conventional behavior control device, and the main problem of the present invention is to solve these problems in a situation where spin and drift-out occur simultaneously. The purpose of the present invention is to appropriately control the turning behavior of the vehicle even in a situation in which spin and drift-out occur simultaneously by optimizing the ratio of the front and rear wheels of the braking force according to the degree of the braking force.

[0006]

According to the present invention, the main object as described above is the configuration according to claim 1, that is, means for calculating a target control amount for stabilizing the turning behavior of a vehicle, In a vehicle behavior control device having a target braking force calculation unit that calculates a target braking force of each wheel based on a target control amount, and a braking force control unit that controls a braking force of each wheel based on the target braking force. Means for detecting the amount of spin state of the vehicle, means for detecting the amount of drift-out state of the vehicle,
Means for detecting a support load of the turning inner wheel, wherein the target
The braking force calculation means reduces the supporting load of the turning inner wheel.
When both the spin state amount and the drift-out state amount are respectively equal to or more than predetermined values , the front-rear wheel distribution ratio of the braking force is calculated based on the spin state amount and the drift-out state amount, and the target control amount is calculated . And calculating the target braking force of each wheel based on the front and rear wheel distribution ratio,
The supporting load of the turning inner wheel is small and the vehicle
When a yaw moment in the direction
The larger the yaw moment in the assist direction is, the more the rear wheels are allocated to the braking force
Turn outside front based on the target control amount so as to increase the ratio.
This is achieved by a vehicle behavior control device characterized by calculating a target braking force for a rear wheel .

According to the first aspect of the present invention, the turning inner wheel is supported.
When the load is not small and both the spin state amount and the drift-out state amount are each equal to or greater than a predetermined value , the front and rear wheel distribution ratio of the braking force is calculated based on the spin state amount and the drift-out state amount, and the target control amount and the front and rear wheel amounts are calculated. Since the target braking force of each wheel is calculated based on the distribution ratio, the turning behavior of the vehicle is appropriately controlled not only in a situation where spin or drift out occurs alone but also in a situation where these occur simultaneously. You.

[0008]

Generally, when the vehicle is in a drift-out state and it is necessary to apply a yaw moment in the turning assist direction to the vehicle, it is effective to apply a braking force to the turning inner wheel. When the supporting load is small, the turning inner wheel cannot generate a sufficient braking force even if the braking pressure of the turning inner wheel is increased. Large rear wheel distribution ratio of braking force
The lateral force of the front wheel increases and the lateral force of the rear wheel decreases
So the vehicle tends to oversteer and drifts out
The condition is reduced. According to the configuration of the first aspect , when the supporting load of the turning inner wheel is small and the yaw moment in the turning assist direction is to be given to the vehicle, the yaw moment in the turning assist direction is provided.
The larger the ment, the larger the rear wheel distribution ratio of the braking force
The target braking force of the front and rear wheels outside the turning
The vehicle is decelerated and the vehicle is over
Reduced drift-out due to steer tendency
As a result, the turning behavior of the vehicle is reliably stabilized even if the supporting load of the turning inner wheel is small.

[0010] According to the present invention, in order to effectively achieve the above-mentioned main object, the driver according to the first aspect of the present invention is provided.
Means for calculating the deceleration rate Gxt desired by the driver based on the braking force operation of the vehicle, and means for calculating the target additional deceleration dGxt so as to decrease as the deceleration rate Gxt increases. Target yaw moment Mt for stabilizing the turning behavior of the vehicle and the target additional deceleration dGxt
And the target additional deceleration dGxt
As but that the target braking force of the inner turning wheel to and the target yaw moment Mt is negative sometimes the target braking force is a yaw moment of the swivel auxiliary direction is calculated the turning inner basis wheels is set to 0 (Claim 2 )
Configuration).

[0011] According to this configuration, the target additional deceleration dG is set so as to decrease as the deceleration total Gxt desired by the driver increases.
xt is calculated, and the braking means is controlled in accordance with the linear sum of the target yaw moment Mt and the target additional deceleration dGxt, so that the deceleration desired by the driver is high while achieving the deceleration desired by the driver. deterioration of behavior lateral force of the wheel by the braking force becomes excessive for the wheels is caused to drop Ru is reliably prevented when. When the target additional deceleration dGxt is negative and a yaw moment in the turning assist direction is to be given to the vehicle , in other words, the braking force by the driver's braking operation is high.
The braking force must be reduced to secure the lateral force of the wheels.
Shall base yaw moment turning assist direction to the vehicle at the conditions given way back Kiniwa, target braking force of the outer turning wheel is calculated the turning inner basis wheels, the braking force of the swivel outer ring of the turning inner wheel Since it is reduced so as to be smaller than the braking force, the lateral force of the wheels is securely ensured and the turning inner and outer wheels are
Yaw moment in turning assist direction due to braking force difference
This makes it possible to reduce the drift-out state and reliably stabilize the turning behavior.

According to the present invention, in order to effectively achieve the above-mentioned main object, in the structure of the first aspect, the vehicle sets a target driving force of driving wheels based on at least a driving force operation by a driver. The braking force control means is configured to control the braking force of the driving wheel based on a linear sum of the target driving force and the target braking force (configuration of claim 3 ).

In general, when the driving force of the driving wheel is controlled by the driver, when the braking force by the turning behavior control is applied to the driving wheel, acceleration becomes suddenly impossible from the start of the turning behavior control. Drivers are dissatisfied with the fact that their desire to accelerate is not reflected. According to the configuration of claim 3 , when the driving force of the driving wheel is operated by the driver, the braking force of the driving wheel is controlled based on the linear sum of the target driving force and the target braking force. Even when the vehicle starts, the wheel speed of the drive wheels does not suddenly decrease and the vehicle cannot accelerate, so that the driver does not feel dissatisfied with the inability to accelerate.

[0014]

According to a preferred aspect of the present invention, in the configuration of the first aspect, the means for calculating the target control amount includes: means for obtaining a slip angle βr of the rear wheel; Means for obtaining a physical quantity βd corresponding to the slip angular velocity βrd, and means for obtaining a target slip angle βrt of the rear wheel determined by a turning degree desired by the driver, and based on the slip angle βr and the physical quantity βd, the slip angle βr of the rear wheel.
Is calculated as a target yaw moment Mt for obtaining the target slip angle βrt (preferred embodiment 1).

According to this configuration, the rear wheel target slip angle βrt determined by the degree of turning desired by the driver is obtained, and the target yaw moment Mt is proportional to the rear wheel slip angle βr and the rear wheel slip angular velocity βrd. The yaw moment is calculated as a PD control amount of the yaw moment for setting the rear wheel slip angle βr to the target slip angle βrt based on the physical quantity βd, and each wheel is provided with the yaw moment having the rear wheel slip angle as the target slip angle. Is controlled, so that the turning behavior of the vehicle is appropriately controlled not only in a situation where spin or drift out occurs alone, but also in a situation where these occur simultaneously.

For example, when the vehicle is in a drift-out state, the rear wheel slip angle βr becomes smaller than the target slip angle βrt, and when the drift-out state increases, the physical quantity βd proportional to the rear wheel slip angular velocity βrd is also a negative value. become. In such a situation, the yaw moment applied to the vehicle is a yaw moment in a direction to assist the turning of the vehicle, so that the drift-out state is reliably suppressed.

When the vehicle is in the spin state, the slip angle βr of the rear wheels becomes larger than the target slip angle βrt, and when the spin state increases, the physical quantity βd becomes a positive value. In such a situation, the yaw moment applied to the vehicle becomes a yaw moment (anti-spin moment) in the direction opposite to the direction that assists the turning of the vehicle, so that the spin state is effectively suppressed.

Further, when the vehicle is in the spin state and in the drift-out state, the direction of the yaw moment applied to the vehicle is appropriately controlled according to the degree of those states, and the degree of the two states When the vehicle turns each other while the vehicle is turning, the direction of the yaw moment is appropriately controlled in accordance with the change. Therefore, even if the spin state and the drift-out state occur simultaneously, control is performed so that the turning behavior of the vehicle is reliably stabilized.

According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 1, the target yaw moment Mt is determined at least according to a deviation between the rear wheel slip angle βr and the target slip angle βrt. It is configured to be operated (preferred mode 2). According to this configuration, the target yaw moment Mt is calculated according to at least the deviation between the slip angle βr of the rear wheels and the target slip angle βrt. A large yaw moment is applied to the vehicle, whereby the turning behavior of the vehicle is reliably stabilized.

According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 1, the vehicle speed
And a means for detecting the degree of instability of the turning behavior that indicates the degree of rotation or drift-out, and means for increasing the target yaw moment Mt as the degree of instability increases (Preferred Embodiment 3). According to this configuration, the higher the degree of instability of the turning behavior of the vehicle, the higher the target yaw moment M
Since t is increased, the higher the degree of instability of the turning behavior of the vehicle, the larger the yaw moment given to the vehicle, which ensures that the turning behavior of the vehicle is stabilized even when the degree of instability of the turning behavior is high. Is done.

In general, the limit slip angle of the rear wheels (slip angle at which the behavior of the vehicle becomes extremely worse when the slip angle is further increased) changes according to the running condition of the vehicle such as the coefficient of friction of the road surface. It is preferable that an upper limit is set for the angle βrt according to the running state of the vehicle.

According to another preferred embodiment of the present invention, in consideration of this point, in order to effectively achieve the above-mentioned main object, in the configuration of the preferred embodiment 1, the vehicle is driven in a running state. There is provided a means for setting the upper limit of the target slip angle βrt accordingly (preferred mode 4). According to this configuration, the target slip angle β depends on the running state of the vehicle.
Since the upper limit of rt is set, the behavior of the vehicle can be reliably prevented from deteriorating due to the target yaw moment Mt becoming excessive.

According to another preferred embodiment of the present invention, in the configuration of the above-mentioned preferred embodiment 1, the means for detecting the steering angular velocity and the target slip angle β increase as the steering angular velocity increases.
means for increasing the phase advance of rt (preferred mode 5).

As described above, the target slip angle βrt of the rear wheels is obtained according to the degree of turning desired by the driver, for example, the slip angle of the front wheels and the steering angle. However, when the steering angle speed increases, the braking force of the rear wheels is controlled. Delay is likely to occur. On the other hand, according to the configuration of the preferred aspect 5, the steering angular velocity is detected, and the phase advance of the target slip angle βrt is increased as the steering angular velocity increases. The power is controlled, which effectively controls the turning behavior of the vehicle.

According to another preferred embodiment of the present invention, in the configuration of the above-mentioned preferred embodiment 3, the means for detecting the degree of instability of the turning behavior of the vehicle includes at least the spin state quantity of the vehicle as the degree of instability. detecting a configuration such that the detection of the spin state quantity is performed based on the minimum value βs slip angle of at the vehicle body at a position near the slip angle by Rikuruma body linear theory of the vehicle is estimated to be zero (Preferred embodiment 6).

According to this configuration, at least detected spin state amount of the vehicle as instability degree of the turning behavior of the vehicle, the detection of the spin state quantity is slip angle of the linear theory by Rikuruma body of the vehicle is zero Is performed based on the minimum value βs of the slip angle of the vehicle body near the position estimated as
For example, the degree of instability of the turning behavior of the vehicle is obtained more accurately than when the spin amount is detected based on the slip angle of the vehicle body at the center of gravity of the vehicle, whereby the target yaw moment Mt is accurately calculated. You.

According to another preferred embodiment of the present invention, in the configuration of the above-mentioned preferred embodiment 3, there is provided means for determining a deviation between the actual yaw rate of the vehicle body and the reference yaw rate of the vehicle body, and the turning behavior of the vehicle is provided. The means for detecting the degree of instability of the vehicle detects at least the amount of spin state of the vehicle as the degree of instability. The means for calculating the target yaw moment Mt, which is a linear sum with the component M2, is configured to increase the weight of the second component as the spin state quantity decreases (preferred embodiment 7).

According to this configuration, the target yaw moment M
t is calculated as a linear sum of the first component M1 based on the slip angle βr and the physical quantity βd and the second component M2 based on the deviation between the actual yaw rate of the vehicle body and the reference yaw rate of the vehicle body. Since the weight of the second component is increased, when the degree of spin is high, the weight of the first component is relatively high, and the spin is effectively suppressed,
Conversely, when the degree of drift-out is high, the weight of the first component, which is susceptible to the estimation error of the slip angle of the rear wheel, is relatively reduced and the second component, which can effectively control the drift-out, The weight is made relatively high, so that even when the vehicle changes from the drift-out state to the spin state or vice versa, the turning behavior of the vehicle is smoothly controlled.

According to yet another preferred embodiment of the present invention, in the configuration of the preferred embodiment 1, the target slip angle βrt of the rear wheel is a steering angle of the front wheel, a slip angle of the front wheel, a reference yaw rate of the vehicle. It is obtained according to any of the drift-out state quantities based on the deviation from the actual yaw rate. According to this configuration, the target slip angle βrt of the rear wheels is reliably obtained according to the turning degree desired by the driver.

According to still another preferred embodiment of the present invention, in the configuration of the preferred embodiment 2, the linear sum of the rear wheel slip angle βr and its differential value βrd is determined by the target rear wheel slip angle. When it is larger than βrt, the calculation coefficient of the target yaw moment Mt based on the deviation between the rear wheel slip angle βr and the target slip angle βrt is set large. According to this configuration, the possibility that the behavior of the vehicle becomes suddenly unstable due to the slip angle of the rear wheel exceeding the limit value is reduced.

According to still another preferred embodiment of the present invention, in the configuration of the aforementioned preferred embodiment 3, the means for detecting the degree of instability of the turning behavior of the vehicle is based on at least the vehicle slip angle β. And the drift-out state quantity based on the deviation between the reference yaw rate and the actual yaw rate of the vehicle, and the degree of instability of the turning behavior is calculated as the sum of these state quantities or the larger of these state quantities. Is determined.

According to still another preferred embodiment of the present invention, in the configuration of the preferred embodiment 4, the upper limit of the target slip angle βrt is set at least according to a friction coefficient of a road surface. According to this configuration, even when the coefficient of friction of the road surface is low, the behavior of the vehicle is surely prevented from being deteriorated by controlling the braking force of each wheel based on the target yaw moment Mt.

According to still another preferred embodiment of the present invention, in the configuration of the above-mentioned preferred embodiment 6, means for detecting the degree of instability of the turning behavior of the vehicle is provided with a target with a higher degree of instability. Means for increasing the acceleration / deceleration dGxt. According to this configuration, the higher the degree of instability of the turning behavior of the vehicle, the greater the degree of deceleration of the vehicle, whereby the turning behavior of the vehicle is more reliably stabilized even when the degree of instability of the turning behavior is high. You.

[0034]

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 showing a hydraulic circuit and an electric control device of one embodiment of a behavior control device according to the present invention.

In FIG. 1, a braking device 10 includes a master cylinder 14 for pumping brake oil from first and second ports in response to a driver's depressing operation of a brake pedal 12, and an oil pressure in the master cylinder. And a hydraulic booster 16 for increasing the brake oil to a pressure (regulator pressure) corresponding to the pressure. Master cylinder 1
The first port 4 is a brake hydraulic control conduit 18 for the front wheels.
The second port is connected to a three-port two-position switching type for left and right rear wheels by a rear wheel brake hydraulic control conduit 26 having a proportional valve 24 on the way. It is connected to an electromagnetic control valve 28. The control valve 28 is connected by a conduit 30 to a brake hydraulic control device 32 for the left rear wheel and a brake hydraulic control device 34 for the right rear wheel.

The brake device 10 has an oil pump 40 that draws up brake oil stored in the reservoir 36 and supplies it to the high-pressure conduit 38 as high-pressure oil. The high-pressure conduit 38 is connected to the hydro booster 16, and is also connected to a front-wheel switching valve 42 and a rear-wheel switching valve 44.
An accumulator 46 that accumulates high-pressure oil discharged from the accumulator as an accumulator pressure is connected. As shown, the switching valves 42 and 44 are also three-port two-position switching type electromagnetic switching valves.

The brake hydraulic control devices 20 and 22 for the left and right front wheels include wheel cylinders 48FL and 48FR for controlling braking force on the corresponding wheels, 3-port 2-position switching type electromagnetic control valves 50FL and 50FR, and a reservoir. Low pressure conduit 5 as return passage connected to 36
The normally open solenoid-operated on-off valves 54FL and 54FR and the normally-closed electromagnetic on-off valves 56FL and 56FL provided in the middle of the regulator pressure supply conduit 53 connected between the hydraulic pump 2 and the discharge port of the hydro booster 16. 56FR. The regulator pressure supply conduit 53 between the on-off valves 54FL, 54FR and the on-off valves 56FL, 56FR respectively has connection conduits 58FL, 58
FR is connected to control valves 50FL and 50FR.

Brake hydraulic pressure control device 32 for left and right rear wheels,
Reference numeral 34 denotes a normally-open electromagnetic on-off valve 60RL, 60 provided between the control valve 28 and the low-pressure conduit 52 in the middle of the conduit 30.
RR and normally closed solenoid-operated on-off valves 62RL, 62RR, and wheel cylinders 64RL, 64RR for controlling braking force on the corresponding wheels, respectively.
RL and 64RR are connected to the conduit 30 between the on-off valves 60RL and 60RR and the on-off valves 62RL and 62RR by connecting conduits 66RL and 66RR, respectively.

The control valves 50FL and 50FR are respectively a brake hydraulic control conduit 18 for the front wheels and a wheel cylinder 48FL.
And 48FR and wheel cylinder 48FL
, 48FR and the connection conduits 58FL and 58FR, the first position shown in the figure, the brake hydraulic control conduit 18 and the wheel cylinders 48FL and 48FR are disconnected, and the wheel cylinders 48FL and 48FR are connected to the connection conduit 58FL.
, And 58FR.

A regulator pressure supply conduit 68 for the left and right rear wheels is connected between the regulator pressure supply conduit 53 and the left and right rear wheel control valves 28, and the control valves 28 are respectively brake oil pressure control conduits for the rear wheels. 26 and on-off valve 60RL, 60RR
, And the first position shown in the drawing for interrupting the communication between the on-off valves 60RL, 60RR and the regulator pressure supply conduit 68, the brake hydraulic control conduit 26 and the on-off valves 60RL, 60RR.
And the switching to the second position where the on-off valves 60RL, 60RR and the regulator pressure supply conduit 68 are connected.

The control valves 50FL, 50FR and 28 function as master cylinder pressure shut-off valves, and when these control valves are at the first position shown in the figure, the wheel cylinders 48FL and 48FR
FR, 64RL, 64RR are connected in communication with conduits 18, 26,
By supplying the master cylinder pressure to each wheel cylinder, the braking force of each wheel is controlled according to the amount of depression of the brake pedal 12 by the driver, and the control valves 50FL, 50FL
When 0FR, 28 is in the second position, each wheel cylinder is shut off from the master cylinder pressure.

The switching valves 42 and 44 have the function of switching the hydraulic pressure supplied to the wheel cylinders 48FL, 48FR, 64RL, 64RR between the accumulator pressure and the regulator pressure. The control valves 50FL, 50FR, 28 Is switched to the second position and the on-off valves 54FL, 54FR, 60RL, 60
When the switching valves 42 and 44 are maintained at the illustrated first positions while the RR and the on-off valves 56FL, 56FR, 62RL, and 62RR are at the illustrated positions, the wheel cylinder 48FL,
By supplying the regulator pressure to the 48FR, 64RL, and 64RR, the pressure in each wheel cylinder is controlled by the regulator pressure, whereby the braking of that wheel is performed regardless of the amount of depression of the brake pedal 12 and the braking pressure of the other wheels. The pressure is controlled in a pressure increase mode by a regulator pressure.

Even if each valve is switched to the pressure increasing mode by the regulator pressure, when the pressure in the wheel cylinder is higher than the regulator pressure, the oil in the wheel cylinder flows backward, and the control mode is the pressure increasing mode. Nevertheless, the actual braking pressure decreases.

The control valves 50FL, 50FR, 28 are switched to the second position, and the on-off valves 54FL, 54FR, 60RL,
When the switching valves 42 and 44 are switched to the second position with the 60RR and the opening / closing valves 56FL, 56FR, 62RL, and 62RR in the illustrated positions, the wheel cylinders 48FL, 48F
By supplying the accumulator pressure to R, 64RL, and 64RR, the pressure in each wheel cylinder is controlled at an accumulator pressure higher than the regulator pressure, thereby affecting the amount of depression of the brake pedal 12 and the braking pressure of other wheels. Instead, the braking pressure of the wheel is controlled in the pressure increasing mode by the accumulator pressure.

Further, with the control valves 50FL, 50FR, 28 switched to the second position, the on-off valves 54FL, 54FR, 6
0RL and 60RR are switched to the second position, and the on-off valve 56F
When L, 56FR, 62RL, and 62RR are controlled to the state shown in the figure, the pressure in each wheel cylinder is maintained regardless of the positions of the switching valves 42 and 44, and the control valves 50FL, 50FR, 28
Are switched to the second position and the on-off valves 54FL, 5FL
4FR, 60RL, 60RR and open / close valve 56FL, 56FR, 62
When RL and 62RR are switched to the second position, the switching valve 42
The pressure in each wheel cylinder is reduced irrespective of the positions of and 44, whereby the braking pressure of the wheel is controlled in the reduced pressure mode regardless of the amount of depression of the brake pedal 12 and the braking pressure of the other wheels.

Switching valves 42 and 44, control valves 50FL, 50
FR, 28, on-off valves 54FL, 54FR, 60RL, 60RR and on-off valves 56FL, 56FR, 62RL, 62RR are controlled by an electric control device 70 as described later in detail. The electric control device 70 includes a microcomputer 72 and a drive circuit 74. The microcomputer 72 includes, for example, a central processing unit (CPU), a read-only memory (ROM), not shown in detail in FIG. , A random access memory (RAM), and an input / output port device, which may be connected to each other by a bidirectional common bus.

A signal indicating the vehicle speed V from the vehicle speed sensor 76, a signal indicating the lateral acceleration Gy of the vehicle body from a lateral acceleration sensor 78 provided substantially at the center of gravity of the vehicle body, a yaw rate sensor 80 A signal indicating the yaw rate γ of the vehicle body, a signal indicating the steering angle θ from the steering angle sensor 82, a signal indicating the longitudinal acceleration Gx of the vehicle body from a longitudinal acceleration sensor 84 provided substantially at the center of gravity of the vehicle body, the wheel speed sensors 86FL From 86RR, the wheel speeds (peripheral speeds) Vwi (i = fl, fr, r
l, rr). The lateral acceleration sensor 78, the yaw rate sensor 80, and the like detect lateral acceleration and the like with the left turning direction of the vehicle as positive, and the longitudinal acceleration sensor 84 detects longitudinal acceleration with the acceleration direction of the vehicle as positive.

The ROM of the microcomputer 72 stores various control flows and maps as described later, and the CPU performs various calculations as described below based on the parameters detected by the various sensors described above, and The turning behavior is determined, the target braking force of each wheel for stabilizing the turning behavior of the vehicle is calculated, and the braking force of each wheel is controlled based on the calculation result.

Although not shown in FIG. 1, the microcomputer 72 has a traction control (TR
C) A control command signal for traction control from the device, a signal indicating the throttle opening φ from a sensor for detecting the throttle opening of the engine, and a signal indicating the braking oil pressure Pb from a pressure sensor for detecting the pressure in the master cylinder 14 are input. The electric control device 70 controls the braking force of the rear wheels as necessary based on a command signal from the traction control device.

Next, the outline of the behavior control of the vehicle will be described with reference to the general flowchart shown in FIG.
The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch (not shown) and is repeatedly executed at predetermined time intervals.

First, at step 50, the vehicle speed sensor 7
6, a signal indicating the vehicle speed V detected is read, and in step 100, the lateral acceleration deviation is calculated as the deviation Gy-V * γ between the lateral acceleration Gy and the product V * γ of the vehicle speed V and the yaw rate γ. That is, the lateral slip acceleration Vyd of the vehicle is calculated, and the deviation Vyd of the lateral acceleration is integrated to calculate the lateral slip speed Vy of the vehicle, and the longitudinal speed Vy of the vehicle is calculated.
The ratio V of the vehicle body slip speed Vy to x (= vehicle speed V)
The slip angle β of the vehicle body at the center of gravity of the vehicle as y / Vx
Is calculated. Further, the friction coefficient μ of the road surface with respect to the wheel is estimated and calculated according to, for example, the following equation 1 with g as the gravitational acceleration. The slip angle β of the vehicle body and the side slip acceleration Vyd of the vehicle may be measured values.

Μ = (Gx2 + Gy2) ^1/2 / g

In step 150, FIG.
The spin value SV indicating the degree of spin of the vehicle and the drift-out of the vehicle according to the flowchart shown in FIG.
The drift value DV indicating the degree is calculated, and the spin control amount Cs and the drift control amount C
d is calculated, and the total control amount Ct is calculated as the sum of these control amounts.

In step 200, the target yaw moment control amount Mt is determined according to the flowchart shown in FIG.
In step 250, the target additional deceleration dGxt is calculated according to the flowchart shown in FIG. 5, and in step 300, the front wheel distribution ratio Kf (0) of the braking force is calculated according to the flowchart shown in FIG. <Kf 1)
Is calculated.

In step 350, the target yaw moment control amount Mt is determined according to the flowchart shown in FIG.
, Target additional deceleration dGxt and front wheel distribution ratio Kf of braking force
, The target slip ratio Rsti of each wheel is calculated, and in step 400, a reference wheel for controlling the braking force of each wheel, that is, a non-control wheel, is selected in accordance with the flowchart shown in FIG.

In step 450, the target wheel speed Vwti of each wheel is calculated in accordance with the following equation 2 using Vb as the wheel speed of the reference wheel selected in step 400.

## EQU2 ## Vwti = Vb * (1-Rsti)

In step 500, the duty ratio Dri of each wheel is calculated according to the following equation (3). In the following equation 3, Kp and Kd are proportional constants of a proportional term and a differential term in the wheel speed feedback control.

Dri = Kp * (Vwi-Vwti) + Kd * d (V
wi-Vwti) / dt

In step 550, the control valve 5 for each wheel
By outputting a control signal to 0FL to 50RR, the control valve is switched to the second position, and a control signal corresponding to the duty ratio Dri is output to the on-off valve of each wheel. Wheel cylinder 48FL
The supply / discharge of the accumulator pressure to .about.48RR is controlled, thereby controlling the braking pressure of each wheel.

In this case, when the duty ratio Dri is between the negative reference value and the positive reference value, the upstream open / close valve is switched to the second position and the downstream open / close valve is set to the first position. By holding the position, the pressure in the corresponding wheel cylinder is held, and when the duty ratio is equal to or more than the positive reference value, the upstream and downstream open / close valves are controlled to the positions shown in FIG. By supplying the accumulator pressure to the corresponding wheel cylinder, the pressure in the wheel cylinder is increased. When the duty ratio is equal to or less than the negative reference value, the upstream and downstream open / close valves are in the second position. , The brake oil in the corresponding wheel cylinder is supplied to the low-pressure conduit 52.
To reduce the pressure in the wheel cylinder.

Next, a calculation routine of the spin value SV, the drift value DV, and the total control amount Ct will be described with reference to the flowchart shown in FIG.

First, in step 152, M is the mass of the vehicle, H is the wheelbase as shown in FIG. 22, Lf and Lr are the center of gravity Pg of the vehicle, the front wheel axle 100 and the rear wheel axle, respectively. 102, and Cr as the cornering power of the rear wheel.
The distance Z in the longitudinal direction from the center of gravity Pg of the vehicle to the position Po where the slip angle of the vehicle body becomes 0 in the linear theory according to
p (positive after the vehicle) is calculated.

Equation 4] Zp = Lr * {1- (M * Lf * V 2) / (2 H * Lr * Cr)}

[0062] is in step 154 position ± than location Po
In the range of Lp / 2 (Lp is a positive constant), a distance α in the front-rear direction from the center of gravity Pg of the vehicle to a position (referred to as a reference position) at which the slip angle of the vehicle body becomes a minimum value is calculated.

In the graph shown in FIG. 21, that is, in the orthogonal coordinates having the horizontal axis of −V * β / γ and the vertical axis of α, the distance α is such that the linearly inclined portion passes through the origin and the inclination is 1 extending along a straight line having upper and lower limits of Zp + Lp /
2, Zp -Lp / 2 a is not good is computed from a map corresponding to the graph.

In step 156, the slip angle βs of the vehicle body at the reference position, that is , the position at a distance α from the center of gravity Pg of the vehicle is calculated according to the following equation (6).

[Formula 6] βs = β + α * γ / V

In step 158, the spin value SV is calculated in accordance with the following equation (7) using Ks as a positive constant based on the slip angle β of the vehicle body and the skid acceleration Vyd of the vehicle calculated in step 50 described above. You.

[ Expression 7] SV = βs + Ks * Vyd

The slip angle β of the vehicle body at the center of gravity of the vehicle and the vehicle slip acceleration Vyd at the center of gravity of the vehicle, which are used in the calculations of Equations 6 and 7, respectively, may be the values calculated in Step 50 described above. , These may be measurements.

In step 160, the target yaw rate γc is calculated according to the following equation 8 using Kh as a stability factor, and the reference yaw rate γt is calculated according to the following equation 9 using T as a time constant and s as a Laplace operator. Is done.

Γ c = V * θ / (1 + Kh * V ² ) * H

Γt = γc / (1 + T * s)

In step 162, the drift value DV is calculated according to the following equation (10) or (11).

DV = H * (1 + Kh * V ² ) * (γt−
γ) / V-βs

DV = H * (γt−γ) / V

The drift value DV may be set to the slip angle βf of the front wheel. However, the reference yaw rate γt is calculated according to Equations 8 and 9 so that the reference yaw rate γt does not deviate from the actual yaw rate γ as much as possible. Unnecessary braking control can be reduced as compared with the case where the angle is set to βf.

In step 164, the spin control amount Cs is calculated from the map corresponding to the graph shown in FIG. 9 based on the absolute value of the spin value SV. Similarly, in step 166, the absolute value of the drift value DV is calculated. The drift control amount Cd is calculated from the map corresponding to the graph shown in FIG. 10 based on the values, and in step 168, the total control amount Ct is calculated as the sum of the spin control amount Cs and the drift control amount Cd. .

The total control amount Ct may be calculated according to the following equation (12).
It may be set to the larger value of d.

## EQU12 ## Ct = Cs + Cd-Cs * Cd

Ct = Cs (Cs> Cd) Ct = Cd (Cd> Cs)

Next, the routine for calculating the target yaw moment control amount Mt will be described with reference to the flowchart shown in FIG.

First, in step 202, it is determined whether or not traction control is being performed. If a negative determination is made, in step 204, the reference value βrlb for calculating the limit rear wheel slip angle is set to the following value. 14 and when an affirmative determination is made in step 206
The reference value βrlb is calculated according to the following equation (15). In the following equations 11 and 12, a1, a2, b1, and b2 are positive constants, respectively, and a1> a2,
b1> b2.

[0074]

[Formula 14] βrlb = a1 * μ + b1

[Formula 15] βrlb = a2 * μ + b2

Considering the characteristics of the tire, the calculation reference value βrlb of the limit rear wheel slip angle is proportional to the friction coefficient μ of the road surface. However, the estimation accuracy of the friction coefficient of the road surface is limited, and the friction coefficient of the road surface is limited. In the above equations (14) and (15), b1 in the above equations (14) and (15) has a slightly larger slip angle at the time of turning the vehicle even when the vehicle is low, because the occupant of the vehicle can be given a sense of security.
And b2 are set as positive constants.

In step 208, the braking / driving torque Tr of the rear wheels is estimated and calculated based on the braking oil pressure Pb, the intake air amount of the engine, and the like in a known manner, and corresponds to the graph shown in FIG. The coefficient Kt is calculated from the map, and in step 210, the limit rear wheel slip angle βrl is calculated according to the following equation (16). In the graph of FIG. 11, Trul is the upper limit value of the braking / driving torque of the rear wheels, which is proportional to the road surface friction coefficient and the ground contact load of the rear wheels.

[Formula 16] βrl = Kt * βrlb

In step 212, the slip angle βf of the front wheel is calculated by the following equation (17) using Nsg as the steering gear ratio.
The actual steering angular velocity δfd of the front wheel is calculated as a differential value of the actual steering angle δf (= θ / Nsg) of the front wheel, and the target of the rear wheel is calculated according to the following equation 18 using Ts as the time constant of the phase advance. Reference value β for calculating slip angle βrt
fs is calculated. The reference value βfs may be calculated according to the following equation (19).

[0078]

[Number 17] βf = β + L f * γ / V -θ / Nsg

[Expression 18] βfs = βf + Ts * δfd

[Equation 19] βfs = DV + Ts * δfd

In step 214, Cf is set to the cornering power of the front wheel, and C is set to (Cf * Lf) / (Cr *).
The target slip angle βrt of the rear wheel is calculated as Lr) according to the following equation (20). That is, in the linear region, since the slip angles of the front and rear wheels have the ratio of the above-mentioned C, the target slip angle βrt of the rear wheel is calculated so as not to exceed the limit rear wheel slip angle βrl using C as a target value.

[Equation 20] βrt = βrl * tanh (βfs * C)

The rear wheel target slip angle βrt is obtained by plotting the graph shown in FIG. 12, that is, the reference value βfs for calculating the rear wheel target slip angle βrt on the horizontal axis, and the rear wheel target slip angle βrt on the vertical axis. Corresponding to a graph in which a linear inclined portion extends along a straight line having a slope of C (almost 1) passing through the origin and having an upper limit and a lower limit of βrl and −βrl, respectively, in orthogonal coordinates as axes. It may be calculated from a map.

In step 216, the rear wheel slip angle βr is calculated according to the following equation (21), its differential value βrd is calculated, and B is set to β as a positive constant.
Assuming that r + K * βrd, the following equation 2 is used according to the size of B.
2, a first component M1 of the target yaw moment Mt,
That is, the rear wheel slip angle βrl and the rear wheel target slip angle βrt
Is calculated based on the deviation from. Note that M0 is a positive constant in Expression 22 and Expression 23 described later.

[0082]

## EQU21 ## βr = β + Lr * γ / V

When | B |> βrl, M1 = M0 * (βr + K * βrd) When βrt <B <βrl M1 = {βrl * M0 / (βrl−βrt)} (βr−βrt +
K * βrd) −βrl <B <βrt M1 = {βrl * M0 / (βrl + βrt)} (βr−βrt +
K * βrd)

The first component M of the target yaw moment Mt
1 may be calculated from a map corresponding to the graph shown in FIG. 13 in which βr + K * βrd is the horizontal axis and the first component M1 is the vertical axis.

In step 218, the second component M2 of the target yaw moment Mt, that is, the component based on the deviation between the reference yaw rate γt and the actual yaw rate γ is calculated according to the following equation (23).

## EQU23 ## M2 = M0 * H * (γt -γ) / V

In step 220, the weight Wy of the second component M2 is calculated from the map corresponding to the graph shown in FIG. 14 based on the absolute value of the spin value SV, and in step 222, According to 24, the target yaw moment Mt is calculated as a linear sum of the first component M1 and the second component M2.

Mt = μ * Ct * {(1-Wy) * M1 + Wy * M2}

Next, the routine for calculating the target additional deceleration dGxt will be described with reference to the flowchart shown in FIG.

First, at step 252, the target deceleration Gxt of the driver is calculated from a map corresponding to the graph shown in FIG. 15 based on the throttle opening φ or the braking oil pressure Pb. In FIG. 15, Pbo is the hydro booster 16
When the braking oil pressure exceeds Pbo, the amount of the assist cut of the hydro booster is corrected.

In step 254, the reference value dG of the additional deceleration is obtained from the map corresponding to the graph shown in FIG. 16 based on the target deceleration Gxt of the driver and the friction coefficient μ of the road surface.
xt0 is calculated, and in step 256,
5, the target additional deceleration dGxt is calculated.

DGxt = μ * Ct * dGxt0

Next, the routine for calculating the front wheel distribution ratio Kf of the braking force will be described with reference to the flowchart shown in FIG.

First, in step 302, it is determined whether or not the behavior control is being performed. If the determination is affirmative, in step 304, it is determined whether or not the target deceleration Gxt of the driver is positive. of discrimination, namely the driver wishes to brake braking
Operate is judged whether or not Ru Tei performed, whether when made or positive determination is inwardly target yaw moment Mt, which is calculated one cycle before in step 306 (turning assist direction) Judgment, ie, target yaw moment Mt
Is determined to be the same as the direction of the lateral acceleration Gy. If an affirmative determination is made, step 308 is executed.
Proceed to. When a negative determination is made in steps 302 to 306, the process proceeds to step 318.

In step 308, the outer wheel flag Fou
It is determined whether or not t is 1; if a positive determination is made, the coefficient Kflag is set to 1 in step 310; if a negative determination is made, step 312 is performed.
Is reset to zero. Flag F
out is a situation in which it is desired to brake the turning inner wheel to generate an inward yaw moment, but since the supporting load of the turning inner wheel is small and it is not possible to generate sufficient braking force,
This relates to whether or not it is inevitable to apply a braking force to the turning outer wheel. In step 314, the lateral acceleration determination value Gyde is calculated according to the following equation (26).

In step 316, it is determined whether or not the lateral acceleration determination value Gyde exceeds a reference value Gyo (positive constant). If a negative determination is made, step 3 is performed.
In step 18, the outer wheel flag Fout is reset to 0. In step 320, the rear wheel distribution ratio Kr is calculated from the map corresponding to the graph shown in FIG. 17, and if a positive determination is made, the process proceeds to step 322. And outer ring flag Fou
t is set to 1, and in step 324 the rear wheel distribution ratio Kr is calculated from a map corresponding to the graph shown in FIG. In step 326, the front wheel distribution ratio Kf
Is calculated according to the following Expression 27. 17 and FIG.
8, Kr1 to Kr7 are Kr1 = 1 <Kr2 <Kr3 <Kr4
It is a constant satisfying <Kr5 <Kr6 <Kr7 = 1.

Kf = 1−Kr

Next, the routine for calculating the target slip ratio Rsti for each wheel will be described with reference to the flowchart shown in FIG.

First, in step 352, it is determined whether or not the outer wheel flag Fout is 1. If a negative determination is made, the process directly proceeds to step 356. After the target yaw moment Mt is set to 0 in step 354 to control the yaw moment by the distribution, the process proceeds to step 356.

In step 356, a is a positive constant, dGxtf is 9.8 * M * dGxt, Gwy and Gwx
Are positive constants, and T is the tread of the vehicle, and the target braking force Fxti of each wheel is calculated according to the following Expression 28.

Fxtfl = ｛Mt / (T * cosδf−a * sinδf) + dGxtf｝ * Kf * (1−Gy / Gwy−Gx / Gwx) Fxtfr = ｛− Mt / (T * cosδf + a *) sin δf) + dGxtf｝ * Kf * (1 + Gy / Gwy-Gx / Gwx) Fxtrl = ｛Mt / T + dGxtf｝ * (1-Kf) * (1-Gy / Gwy + Gx / Gwx) Fxtrr = ｛-Mt / TxdGx ｝ * (1-Kf) * (1 + Gy / Gwy + Gx / Gwx)

In step 358, it is determined whether or not the target braking forces Fxtrl and Fxtrr of the driving wheels (the right and left rear wheels) are present. If a negative determination is made, step 364 is performed.
When the determination is affirmative, the traction control device sets the target drive forces Fxdtrl and Fxd of the drive wheels.
The reading of trr is performed, and in step 362, the target driving force of the driving wheel is corrected according to the following equation (29).

Fxtrl = Fxtrl + Fxdtrl Fxtrr = Fxtrr + Fxdtrr

In step 364, the outer wheel flag Fou
It is determined whether or not t is 1; if a negative determination is made, the process directly proceeds to step 370; if an affirmative determination is made, at step 366, Go is set as a positive constant according to the following equation (30). The upper limit value Fxlim of the braking force of the turning outer front wheel is calculated, and in step 368, the magnitude of the braking force Fxi of the turning outer front wheel is limited to the upper limit value Fxlim. If the braking force of the front wheel on the outside of the turn is too high, the lateral force is reduced and a yaw moment in the turn assist direction cannot be generated. Therefore, the upper limit Fxlim is an upper limit for preventing this.

Fxlim = Go * μ * 9.8 * (1+ | Gy |
/ Gwy-Gx / Gwx)

In step 370, the conversion constant from the target braking force Fxti of each wheel and the slip rate from the braking force to the slip rate is represented by Kfs.
The target slip ratio Rst of each wheel according to the following equation 31
i (i = fl, fr, rl, rr) is calculated.

Rsti = Fxtr * Kfs

Next, the reference wheel selection routine will be described with reference to the flowchart shown in FIG.

First, at step 402, it is determined whether or not the outer wheel flag Fout is 1, and if an affirmative determination is made, the process proceeds to step 416; if a negative determination is made, the process proceeds to step 404. In step 404, it is determined whether or not the target additional deceleration dGxt is negative, that is, whether or not braking pressure reduction control is being performed. If a negative determination is made, the process proceeds to step 406. When the determination is affirmative, the routine proceeds to step 412.

In step 406, it is determined whether or not the product Gy * Mt of the lateral acceleration Gy of the vehicle and the target yaw moment Mt is positive, that is, whether or not the target yaw moment is a yaw moment in the turning assist direction. When a negative determination is made, the process proceeds to step 408, and when an affirmative determination is made, the process proceeds to step 410. Also in step 412, the same determination as in step 406 is performed. When a negative determination is made, the process proceeds to step 414, and when an affirmative determination is made, the process proceeds to step 416.

In steps 408 and 416, the target slip ratio Rfti of the front wheel on the inside of the turn is set to 0, so that the front wheel on the inside of the turn is selected as the reference wheel.
At 0 and 414, the reference wheel is set as the turning outer front wheel by setting the target slip ratio Rsti of the turning outer front wheel to 0. The inside or outside of the turn may be determined, for example, by the sign of the yaw rate γ or the lateral acceleration Gy of the vehicle.

Thus, in the illustrated embodiment, the slip angle β of the vehicle body and the coefficient of friction μ of the road surface with respect to the wheels are estimated and calculated in step 100, and the spin value indicating the degree of spin of the vehicle is calculated in step 150. The SV and the drift value DV indicating the degree of drift-out of the vehicle are calculated, and the spin control amount Cs and the drift control amount Cd are calculated based on these values. It is calculated as the sum of two control quantities Cs and Cd.

In step 200, the target yaw moment control amount Mt is calculated. In step 250, the target additional deceleration dGxt is calculated. In step 300, the front wheel distribution ratio Kf of the braking force is calculated. 35
At 0, the target slip ratio Rsti of each wheel is calculated based on the target yaw moment control amount Mt, the target additional deceleration dGxt and the front wheel distribution ratio Kf, and a reference for controlling the braking force of each wheel at step 400. A wheel is selected, a target wheel speed Vwti of each wheel is calculated in step 450, and a duty ratio Dri is calculated in step 500.
In step 550, the control signals are output to the control valves 50FL to 50RR and the opening / closing valves of each wheel, so that the braking pressure of each wheel is controlled according to the duty ratio Dri.

In particular, in step 314 of the routine for calculating the front wheel distribution ratio Kf in the flowchart shown in FIG. 6, the lateral acceleration determination value Gyde based on the magnitude of the lateral acceleration Gy of the vehicle.
When the lateral acceleration determination value is small, in other words, when the supporting load of the turning inner wheel is not small and the turning inner wheel can generate a sufficient braking force, the outer wheel flag Fout is reset to 0 in step 318. At the same time, in step 320, the rear wheel distribution ratio Kr is calculated from a map corresponding to the graph shown in FIG. That is, when the absolute value of the drift value DV is large, the load on the front wheels is large, and when the absolute value of the spin value SV is large, the load on the rear wheels is large. The distribution of the braking force before and after is determined according to the magnitude of the burden on the vehicle. When the rear wheel is near the limit, the braking force distribution of the front wheel is set to be high to secure the lateral force of the rear wheel.

When the lateral acceleration determination value is large, an affirmative determination is made in step 316, whereby the outer wheel flag Fout is set to 1 in step 322, and in step 324 the rear wheel distribution ratio Kr is determined. It is calculated from a map corresponding to the graph shown in FIG. That is, when the lateral acceleration determination value Gyde is large, even if it is desired to brake the turning inner wheel to generate a yaw moment in the turning assist direction, the supporting load of the turning inner wheel is small and a sufficient braking force cannot be generated. I have to brake. Therefore, when the lateral acceleration of the vehicle is large,
When the rear wheel braking force distribution is increased, the front wheel lateral force decreases.
Utilizing the tendency of oversteering due to an increase in the lateral force of the rear wheels, the larger the target yaw moment Mt in the turning assist direction is, that is, the drift-out of the vehicle
Is higher, the distribution of braking force for the rear wheels is increased so that the vehicle tends to oversteer, and when the rear wheels are near the limit, the distribution of braking force for the front wheels is set higher.

[0107] Thus, when the support load of the turning inside wheel is of sufficient value the vehicle behavior is stabilized by the front and rear distribution of the braking force of the inner turning wheel is optimized, also insufficient support load of the turning inner wheel In some cases, the braking force of the turning outer wheel is controlled, and the front-rear distribution ratio is optimized according to the magnitude of the spin value SV and the target yaw moment Mt, thereby stabilizing the behavior of the vehicle.

In particular, in the illustrated embodiment, the lateral acceleration determination value Gyde is calculated as a value including a hysteresis term in accordance with Equation 26, so that the magnitude of the lateral acceleration of the vehicle is frequently switched. Thus, it is possible to prevent the state in which the turning inner wheel is braked and the state in which the turning outer wheel is braked from being frequently switched, thereby stably controlling the turning behavior of the vehicle.

Further, according to the illustrated embodiment, when the supporting load of the turning inner wheel is a value sufficient to generate the braking force, step 40 of the reference wheel selecting routine shown in FIG.
A negative determination is made in step 2, and in step 404, the braking force by the driver's braking operation is high and the wheel lateral force is secured.
It is determined whether or not the situation is such that the braking force should be reduced . When the braking force is not to be reduced, it is determined in step 406 whether or not the target yaw moment Mt is in the turning assist direction. Step 410 when there is
Front outside wheel at the is set to the reference wheel, thereby
Turning by increasing the braking force of wheels other than the reference wheel
Times yaw moment of the auxiliary direction is generated, when the target yaw moment is the turning assist direction is a backward direction is set to the turning inner front wheel reference wheels in step 408, this
Les yaw moment in the reverse direction occurs to the turning assist direction I by <br/> that the braking force of the wheels other than the reference wheel is increased by
Therefore, a required yaw moment is applied to the vehicle while achieving the deceleration desired by the driver.

On the contrary, the braking force by the driver's braking operation is high.
When the braking force is to be reduced in order to secure the wheel lateral force, it is determined in step 412 whether or not the target yaw moment Mt is in the turning assist direction. is the turning inner front wheel in step 416 is set to the reference wheels when the, this
As a result, the braking force of the outer
Times yaw moment of the auxiliary direction is generated, when the target yaw moment is the turning assist direction is a backward direction is set to the front outside wheel is the reference wheel in step 414, this
He handed me by the fact that the braking force of turning the wheels is reduced by Les
A yaw moment in the direction opposite to the rotation assist direction is generated
Thus, the required yaw moment is applied to the vehicle while achieving the deceleration desired by the driver as much as possible.

Further, when the supporting load of the turning inner wheel is not a value sufficient to generate a sufficient braking force, the outer wheel flag Fout
There is performed affirmative determination in step 402 because it is 1, is set to the reference wheel turning inner front wheel in step 416, the braking force is applied to the turning outer side front and rear wheels by which
The oversteering tendency of the vehicle is controlled by controlling the distribution ratio of the front and rear wheels of the braking force.
The behavior of the vehicle is more stabilized .

Since the drive wheel is not set as the reference wheel,
When a braking force is applied to the drive wheels by the behavior control in a state where the drive slip is controlled by the traction control device, the target of the drive wheels is set immediately after the turning behavior control is started as shown in FIG. When the slip ratio becomes a positive value, the wheel speed of the drive wheel sharply decreases, and the vehicle speed sharply decreases regardless of the driver's intention to accelerate.

On the other hand, according to the illustrated embodiment, FIG.
Step 35 of the target slip ratio calculation routine shown in FIG.
When it is determined in step 8 that the target braking force of the drive wheel is present, in step 360, the target drive force Fxd of the drive wheel is determined.
Since trl and Fxdtrr are read and the target braking force of the drive wheels is corrected in step 362 to the sum of the target braking force calculated in step 356 and the target driving force, the result is shown in FIG. As described above, the target slip ratio of the driving wheel at the start of the turning behavior control is reduced to a negative value, and thereby, it is possible to reliably prevent the wheel speed of the driving wheel from suddenly decreasing.

Also, according to the illustrated embodiment, step 2
A reference value βfs indicating the degree of turning desired by the driver is calculated in 02 to 212, a target slip angle βrt of the rear wheel is calculated in step 214 based on the reference value βfs, and in step 216 the rear wheel is calculated. The first component M1 of the target yaw moment Mt is calculated based on the rear wheel slip angle βr and the rear wheel slip angular velocity βrd as the yaw moment PD control amount for setting the rear wheel slip angle βr to the target slip angle βrt. Therefore, the braking force of each wheel can be controlled so that the yaw moment that gives the slip angle of the rear wheel to the target slip angle determined by the turning degree desired by the driver is given to the vehicle. It is possible to appropriately control the turning behavior of the vehicle not only in a situation where the singly occurs but also in a situation where these occur simultaneously.

In this case, in step 218, the second component M2 of the target yaw moment Mt is calculated based on the yaw rate deviation, and in step 222, the target yaw moment Mt is calculated based on the first component M1 and the second component M2. Although it is calculated as a linear sum with M2, the weight Wy of the second component is calculated so as to gradually decrease as the absolute value of the spin value SV increases in a region where the absolute value of the spin value SV is high.
When the degree of spin is low, the specific gravity of the second component M2 is increased to calculate the target yaw moment Mt, whereby drift-out can be reduced favorably. Conversely, when the degree of spin is high, the first yaw moment Mt can be reduced. By calculating the target yaw moment by increasing the specific gravity of the component M1, the spin can be surely reduced.

In steps 202 to 210, the limit rear wheel slip angle βrl is calculated to be small when the traction control is being performed and a braking force is applied to the rear wheel. The higher the driving torque Tr is, the smaller the calculation is, and the rear wheel target slip angle βrt is calculated using the limit rear wheel slip angle βrl as an upper limit value. In this case, the target slip angle βrt of the rear wheels is prevented from being calculated to an excessive value, whereby the target yaw moment Mt can be properly calculated.

Also, according to the illustrated embodiment, step 2
The reference value βfs for calculating the target slip angle βrt of the rear wheel calculated in step 14 is calculated according to equation 18 or 19 in step 212, so that the higher the actual steering angular velocity δfd of the front wheel, the higher the reference value βfs Is calculated so as to increase the phase advance of the target slip angle βrt. Therefore, even when a relatively fast steering operation is performed by the driver, the yaw moment required for the vehicle without delay in response. , The braking force of each wheel can be controlled.

The target yaw moment Mt is calculated in step 2
22, the friction coefficient μ of the road surface is changed to the first components M1 and M1.
Since the coefficient is calculated as a coefficient with respect to the linear sum of 2, the lower the coefficient of friction of the road surface, the smaller the value of the coefficient. The target yaw moment can be appropriately calculated according to the coefficient of friction of the road surface.

Also, according to the illustrated embodiment, step 1
In steps 52 to 168, a total control amount Ct indicating the degree of instability of the turning behavior of the vehicle is calculated. In step 222, the higher the total control amount, the higher the target yaw moment Mt
Is calculated so that the higher the degree of instability of the turning behavior of the vehicle, the larger the yaw moment can be given to the vehicle. This ensures that the turning behavior is stable even when the degree of instability of the turning behavior is high. Can be changed.

According to the embodiment shown in FIG.
In step 2, the distance Zp in the front-rear direction from the center of gravity Pg of the vehicle to the position Po at which the slip angle of the vehicle body becomes 0 in the linear theory is calculated. / 2 in the range the vehicle body slip angle distance in the longitudinal direction from the center of gravity Pg of the vehicle to the reference position where the minimum value α is calculated, in the vehicle body to the reference position in step 156 based on the α Is calculated, the spin value SV is calculated more accurately than when the slip angle of the vehicle body is calculated as the slip angle at the center of gravity of the vehicle, and the degree of instability of the vehicle is thereby calculated. The total control amount Ct shown can be accurately calculated.

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.

For example, in the illustrated embodiment, in step 216, the first component M of the target yaw moment Mt is calculated.
1 is calculated based on the rear wheel slip angle βr and its differential value βrd, but the differential value βsd of the slip angle of the vehicle body may be used instead of the differential value βrd.

[0123]

As is apparent from the above description, according to the first aspect of the present invention, the supporting load of the turning inner wheel is small.
On the contrary , when both the spin state amount and the drift-out state amount are respectively equal to or more than predetermined values, the front and rear wheel distribution ratio of the braking force is calculated based on the spin state amount and the drift-out state amount, and the target control amount and the front and rear wheel distribution ratio are calculated. Since the target braking force of each wheel is calculated based on this, the turning behavior of the vehicle is appropriately controlled not only in a situation where spin or drift out occurs alone but also in a situation where these occur simultaneously. can do.

According to the first aspect of the present invention, when the supporting load of the turning inner wheel is small and a yaw moment in the turning assist direction is to be given to the vehicle, the yaw moment in the turning assist direction is provided.
So that the rear wheel distribution ratio of the braking force increases as the
Calculates the target braking force of the front and rear wheels on the outside based on the target control amount
The vehicle slows down and overshoots the vehicle.
Drift-out condition is reduced due to tare tendency
As a result, the turning behavior of the vehicle can be reliably stabilized even if the supporting load of the turning inner wheel is small.

According to the configuration of the second aspect, the target additional deceleration dGxt is calculated so as to decrease as the deceleration total Gxt desired by the driver increases, and the braking means calculates the target yaw moment Mt and the target additional deceleration dGxt. Is controlled in accordance with the linear sum of the above, so that while achieving the deceleration desired by the driver, when the deceleration desired by the driver is high, the braking force of each wheel becomes excessive and the lateral force of the wheel decreases. This can reliably prevent the behavior from deteriorating due to
When Gxt is negative and a yaw moment in the turning assist direction should be given to the vehicle , in other words, the driver's braking operation
Braking force is high to secure the lateral force of the wheel
There reduced base yaw moment turning assist direction is applied to the vehicle at the situation must returning Kiniwa, handed
Times the target braking force of the outer ring is calculated the turning inner basis wheels, the braking force of the swivel outer ring is smaller than the braking force of the inner turning wheel
Since it is reduced so that, to reliably secure a lateral force of the wheel
And yaw in the turning assist direction due to the braking force difference between the turning inner and outer wheels.
Gives moment to the vehicle, which gives it a drift-out
And the turning behavior can be reliably stabilized.

According to the configuration of claim 3 , when the driving force of the driving wheel is operated by the driver, the braking force of the driving wheel is controlled based on the linear sum of the target driving force and the target braking force. Even when the turning behavior control is started, the wheel speed of the driving wheels does not suddenly decrease and acceleration becomes impossible, thereby reliably preventing the driver from feeling dissatisfied with the inability to accelerate. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a hydraulic circuit and an electric control device of one embodiment of a behavior control device according to the present invention.

FIG. 2 is a general flowchart showing an outline of behavior control achieved by one embodiment of the behavior control device according to the present invention.

FIG. 3 is a flowchart illustrating a calculation routine of a spin value SV and a drift value DV in the illustrated embodiment.

FIG. 4 shows a target yaw moment M in the illustrated embodiment.
9 is a flowchart illustrating a calculation routine for t.

FIG. 5 shows a target additional deceleration dGx in the illustrated embodiment.
9 is a flowchart illustrating a calculation routine for t.

FIG. 6 shows a front wheel distribution ratio K of the braking force in the illustrated embodiment.
9 is a flowchart illustrating a calculation routine of f.

FIG. 7 is a flowchart showing a routine for calculating a target slip ratio Rsti of each wheel in the illustrated embodiment.

FIG. 8 is a flowchart showing a reference wheel selection routine in the illustrated embodiment.

FIG. 9 shows an absolute value of a spin value SV and a spin control amount C.
6 is a graph showing the relationship between the s and the s.

FIG. 10 is a graph showing a relationship between an absolute value of a drift value DV and a drift control amount Cd.

FIG. 11 is a graph showing a relationship between braking / driving torque Tr of a rear wheel and a coefficient Kt.

FIG. 12 is a graph showing a relationship between a reference value βfs for calculating a rear wheel target slip angle and a rear wheel target slip angle βrt.

FIG. 13 is a graph showing a relationship between βr + K * βrd and a first component M1 of a target yaw moment.

FIG. 14 shows the absolute value of the spin value SV and the second component M
7 is a graph showing a relationship between a weight Wy of two.

FIG. 15 is a graph showing a relationship between a throttle opening φ and a braking oil pressure Pb and a target deceleration Gxt of a driver.

FIG. 16: Gxt / μ and reference value dGxt0 of additional deceleration
6 is a graph showing the relationship between

FIG. 17 is a graph showing the relationship between the absolute value of the spin value SV and the absolute value of the drift value DV and the braking force rear wheel distribution ratio Kr.

FIG. 18 is a graph showing a relationship between the absolute value of the spin value SV, the absolute value of the target yaw moment Mt, and the rear wheel distribution ratio Kr of the braking force.

FIG. 19 is a graph showing changes in the wheel speed and the target slip ratio of the drive wheel when the target braking force is not corrected by the target drive force of the drive wheel.

FIG. 20 is a graph showing changes in the wheel speed and the target slip ratio of the drive wheel when the target braking force is corrected by the target drive force of the drive wheel.

FIG. 21 is a graph showing a relationship between -V * β / γ and a distance α.

FIG. 22 is an explanatory diagram showing a distance Zp in the front-rear direction from the center of the vehicle to a position where the slip angle of the vehicle body becomes 0 in the linear theory.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Braking device 14 ... Master cylinder 16 ... Hydro booster 20, 22, 32, 34 ... Brake hydraulic control device 28, 50FL, 50FR ... Control valve 42, 44 ... Switching valve 44FL, 44FR, 64RL, 64RR ... Wheel cylinder 54FL 54FR, 60RL, 60RR ... open / close valve 56FL, 56FR, 62RL, 62RR ... open / close valve 70 ... electric control unit 76 ... vehicle speed sensor 78 ... lateral acceleration sensor 80 ... yaw rate sensor 82 ... steering angle sensor 84 ... longitudinal acceleration sensor 86FL-86RR … Wheel speed sensor

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60T 8/58

Claims (3)

(57) [Claims] A means for calculating a target control amount for stabilizing a turning behavior of the vehicle; a target braking force calculating means for calculating a target braking force for each wheel based on the target control amount; in the behavior control device of a vehicle and a braking force control means for controlling the braking force of each wheel on the basis of the means for detecting the spin state quantity of the vehicle, means for detecting a drift-out state amount of the vehicle, the turning Hand that detects the support load of the inner ring
And the target braking force calculating means includes a turning inner wheel.
When the supporting load is not small and both the spin state amount and the drift-out state amount are each equal to or greater than a predetermined value , the front-rear wheel distribution ratio of the braking force is calculated based on the spin state amount and the drift-out state amount. Before
The target of each wheel is determined based on the target control amount and the front and rear wheel distribution ratio.
The braking force is calculated, and the supporting load of the turning inner wheel is small and
The vehicle should be given a yaw moment in the turning assist direction
Sometimes the yaw moment in the turning assist direction is large
The target control is performed so that the rear wheel distribution ratio of the braking force increases as the braking force increases.
A vehicle behavior control device for calculating a target braking force for front and rear wheels on the outside of a turn based on the amount . 2. A vehicle behavior control device according to claim 1,
A means for calculating a deceleration rate Gxt desired by the driver based on the driver 's braking force operation; and means for calculating a target additional deceleration dGxt such that the higher the deceleration rate Gxt, the smaller the target control amount. A target yaw moment Mt for stabilizing the turning behavior of the vehicle and the target additional deceleration
The target additional deceleration is calculated as a linear sum with dGxt.
When dGxt is negative and the target yaw moment Mt is the yaw moment in the turning assist direction, the target braking force of the turning inner wheel is set to 0 so that the target braking force is calculated using the turning inner wheel as a reference wheel. A behavior control device for a vehicle, wherein the behavior control device is set to: 3. The vehicle behavior control device according to claim 1,
The vehicle includes a unit that calculates a target driving force of a driving wheel based on at least a driver's driving force operation, and the braking force control unit controls the driving wheel based on a linear sum of the target driving force and the target braking force. A vehicle behavior control device characterized by controlling a braking force.