JPH10250545A - Attitude control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a shortage of the attitude variation on a bad road, and an excessive attitude variation following a wheel stumbling, by making it pos sible to control a turning attitude of a vehicle effectively same as in the case on a plain pavement or the like, even when the running road surface is a bad road, to an attitude control device which is made to control the turning posture of the vehicle to focus a detected vehicle condition amount to a target vehicle condition amount corresponding to the target running direction, by giving a brake force to the wheels independently respectively. SOLUTION: It is decided whether a running road surface of a vehicle 1 is a bad road or not (SC 1), and when it is decided to be a bad road, the upper limit value of a control output amount in order to control a turning posture of the vehicle 1 (the braking force) is set larger than the case decided not to be a bad road (SC 2). And at the same time, a control gain in order to find its control output amount is set larger than the case decided not to be a bad road (SC 4).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle attitude control for controlling a turning posture of a vehicle so as to converge in a target traveling direction by independently applying a braking force to front, rear, left and right wheels of the vehicle. Belongs to the technical field of equipment.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Publication No.
As shown in the publication, the vehicle is configured so that braking force can be individually applied to each of the front, rear, left, and right wheels of the vehicle, and the braking force is applied to each of the wheels independently, so that the vehicle 2. Description of the Related Art There is known a posture control device that controls a turning posture of a vehicle by applying a yaw moment. In such a posture control device, a vehicle state quantity representing a turning posture of the vehicle in a traveling direction such as a yaw rate is detected, and each detected vehicle state quantity is converged to a target vehicle state quantity corresponding to the target traveling direction. By applying a braking force to the wheels, a yaw moment is applied to the vehicle to control the turning posture of the vehicle. This control prevents the vehicle from spinning or drifting out.

[0003]

In the conventional attitude control device, when a large braking force is applied to one of the right and left wheels to apply a large yaw moment to the vehicle, the wheels are locked or the like. Since the stability of the vehicle posture may be impaired, even when the deviation amount between the detected vehicle state amount and the target vehicle state amount is large and yaw momentum needs to be increased, the control amount (operation amount) of the vehicle turning posture control is required. The amount of yam moment to be set is set to an upper limit, or the control gain for obtaining the control amount based on the deviation amount between the detected vehicle state amount and the target vehicle state amount is set to be small, for example, to reduce the control amount. I have. Also, by setting the control amount small, it is possible to prevent the driver from feeling uncomfortable due to the posture control.

However, in the vehicle attitude control apparatus in which the control amount is set to be small as described above, it is possible to effectively control the turning attitude of the vehicle when the running road surface of the vehicle is an ordinary flat paved road or the like. However, when the traveling road surface is a rough road, the effect of the posture control is hardly obtained. That is, in the case of a bad road, if the applied yaw moment is small, the resistance due to the unevenness of the road surface is large, so that the vehicle does not easily turn and it is difficult to change its posture. Further, since the rate of change of the road surface state is large, if the control gain or the like is small and the response is poor, it is not possible to perform detailed control corresponding to the change.

Further, when the vehicle is on a rough road, the attitude of the vehicle may change greatly due to a stumbling of the wheels, and the deviation between the detected vehicle state quantity and the target vehicle state quantity may increase rapidly. It is necessary to control the amount to converge to the target vehicle state amount.

[0006] The present invention has been made in view of the above points, and an object thereof is to control the turning posture of a vehicle by independently applying a braking force to each wheel as described above. By improving the configuration of the attitude control device as described above, even when the traveling road surface is rough, it is possible to effectively control the turning attitude of the vehicle, as in the case of a flat pavement road, An object of the present invention is to prevent an insufficient posture change on a rough road and an excessive posture change due to a wheel stumbling.

[0007]

In order to achieve the above object, according to the present invention, it is determined whether or not a traveling road surface of a vehicle is a rough road. The control amount of the turning posture control of the vehicle by the control means is made larger than when it is determined that the vehicle is not on a rough road.

More specifically, according to the first aspect of the present invention, a braking means configured to be capable of individually applying a braking force to each of the front, rear, left, and right wheels of the vehicle, and a vehicle state indicating a turning posture of the vehicle with respect to a traveling direction. Vehicle state detecting means for detecting the amount of the vehicle, and controlling the operation of the braking means so that the detected vehicle state quantity detected by the vehicle state detecting means converges to a target vehicle state quantity corresponding to a target traveling direction. It is assumed that the vehicle attitude control device includes attitude control means for controlling the turning attitude of the vehicle by independently applying a braking force to each wheel.

A bad road determining means for determining whether or not the traveling road surface of the vehicle is a rough road, and the attitude control means when the rough road determining means determines that the traveling road surface is a bad road. Control amount varying means for setting the control amount of the turning posture control of the vehicle by the means to be larger than when it is determined that the vehicle is not on a rough road.

According to the above configuration, when the road surface of the vehicle is on a rough road, the control amount of the turning posture control of the vehicle is set to be larger than when the vehicle is not on a rough road. And the attitude of the vehicle can be changed against the unevenness of the road surface. At this time,
Since the coefficient of friction of the road surface is usually smaller than when the road is not rough, when the control amount is large, a large braking force is applied to one of the right and left wheels, and the wheels are easily locked and acted. On the contrary, the obtained yaw moment may be small, but in this case as well, the wheels can easily stumble on the unevenness of the road surface, so that the detected vehicle state quantity can be quickly converged to the target vehicle state quantity. Conversely, even if the amount of deviation between the detected vehicle state quantity and the target vehicle state quantity sharply increases due to a wheel stumbling, the attitude of the vehicle can be quickly returned to the target traveling direction. Moreover, even on a rough road, even if the control amount is increased, the driver hardly feels a sense of discomfort due to the attitude control, and the traveling speed of the vehicle is low.
Even if the wheels are locked, the posture rarely becomes unstable.
Therefore, even when the traveling road surface is a rough road, it is possible to effectively control the turning posture of the vehicle as in the case of a flat pavement road, etc., which is accompanied by insufficient posture change on a rough road and wheel stumbling. Excessive posture change can be prevented.

According to a second aspect of the present invention, in the first aspect of the invention, the vehicle state detecting means is configured to detect at least a yaw rate occurring in the vehicle, and the attitude control means is detected by the vehicle state detecting means. The yaw rate control for controlling the turning posture of the vehicle by operating the braking means so that the detected yaw rate converges to the target yaw rate is performed at least, and the rough road determination means determines that the traveling road surface is a rough road. In this case, it is provided with a yaw rate control suppressing means for suppressing the yaw rate control by the attitude control means.

That is, the yaw rate control makes it possible to change the turning posture of the vehicle so as to follow the driving operation of the driver in the case of a flat paved road or the like.
In the case of a rough road, the steering is moved independently of the driver's driving operation due to the kickback of the wheels due to the unevenness of the road surface, and the turning posture of the vehicle changes, so if the yaw rate control is performed, the posture may be disturbed on the contrary. . However, according to the present invention, when it is determined that the traveling road surface is a rough road,
The yaw rate control by the attitude control means is suppressed. For example, if the deviation between the detected yaw rate and the target yaw rate is small, the yaw rate control is not performed, so that the stability of the attitude is not impaired. Further, it is not necessary to change the turning posture of the vehicle so as to follow a movement irrelevant to the driving operation of the driver. On the other hand, even on bad roads,
For example, when the deviation amount between the detected yaw rate and the target yaw rate is considerably large, the change in the attitude of the vehicle due to a wheel stumbling or the like is excessive, and it is worth performing yaw rate control. In such a case, the yaw rate control is performed. By doing so, the control amount is set large,
The detected yaw rate can be quickly converged to the target yaw rate. Therefore, it is possible to prevent an excessive change in the attitude of the vehicle while preventing a problem due to the yaw rate control on a rough road.

According to a third aspect of the present invention, in the first aspect of the invention, the control amount varying means increases a control gain for obtaining a control amount based on a deviation amount between the detected vehicle state amount and the target vehicle state amount. It is assumed to be configured as follows.

Thus, the control amount can be easily increased by increasing the control gain, and the response can be made faster. Therefore, it is possible to easily obtain specific means for increasing the control amount, and it is possible to perform fine-grained attitude control corresponding to a drastic change in the road surface condition.

According to a fourth aspect of the present invention, in the first aspect of the present invention, there is provided a steering amount detecting means for detecting a steering amount of the vehicle by the driver, and the control amount variable means is a steering amount detected by the steering amount detecting means. It is assumed that the control amount is set to be larger as is larger.

Thus, when the steering amount is large, the driver is about to turn the vehicle, so that the control amount can be increased so as to correspond to the operation and the posture of the vehicle can be largely changed. Therefore, posture control that respects the driver's intention can be performed.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the vehicle further comprises a steering amount detecting means for detecting a steering amount of the vehicle by the driver, and the control amount variable means includes a steering amount detected by the steering amount detecting means. It is assumed that the control amount is set to be smaller in a region where is small than in a region where it is large.

As a result, in a region where the steering amount is small, the vehicle is traveling almost straight, although there is a small change in the attitude of the vehicle. Therefore, there is no problem even if the control amount is reduced, and the control amount is increased. It is possible to prevent the posture from becoming unstable due to the movement. Therefore, stable attitude control can be performed.

According to a sixth aspect of the present invention, in the first aspect of the invention, there is provided a steering amount change rate detecting means for detecting a change rate of a steering amount of the vehicle by the driver, and the control amount variable means includes the steering amount change rate detection. It is assumed that the control amount is set to be larger as the steering amount change rate detected by the means is larger.

According to the present invention, even when the rate of change of the steering amount is large, the driver tries to turn the vehicle quickly, so that it is possible to cope with the operation. Therefore, the same function and effect as the fourth aspect of the invention can be obtained.

According to the invention of claim 7, according to claim 1, 4, or 6
In the present invention, the control amount variable means is configured to increase the upper limit value of the control amount set in advance.

In this way, when the deviation amount between the detected vehicle state quantity and the target vehicle state quantity is large, even if the control amount is limited by the upper limit when the vehicle is not on a rough road, even if the control amount is restricted by the upper limit value, Since the upper limit is increased, the control amount can be increased. In addition, by setting the upper limit of the control amount, it is possible to prevent the vehicle posture from becoming unstable due to an excessive control amount, particularly when the road is not bad. Therefore, specific means for increasing the control amount can be easily obtained, and stable control of the vehicle attitude can be performed.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. -Overall Configuration- FIG. 1 is a diagram illustrating a vehicle attitude control device (St.
shows the vehicle 1 to which the Ability Control System is applied,
2, 2, ... are the front and rear four wheels 21FR, 21FL, 21RR,
4 sets of hydraulic brakes individually installed on 21RL, 3
Is a hydraulic unit (hereinafter simply referred to as HU) which supplies a hydraulic fluid to each of the brakes 2 and which distributes the hydraulic fluid supplied from the pressurizing unit 3 to each of the brakes 2. ), These brakes 2, 2,..., The pressurizing unit 3 and the HU 4 constitute a braking means. Reference numeral 5 denotes an SCS controller as attitude control means for controlling the operation of each of the brakes 2 via the pressurizing unit 3 and the HU 4, and 6, 6, ... are wheel speed sensors for detecting wheel speeds of the wheels 21. , 7 are lateral G sensors for detecting the lateral acceleration y ″ acting on the vehicle 1; 8 are yaw rate sensors as yaw rate detecting means for detecting the yaw rate ψ ′ acting on the vehicle 1; A steering angle sensor as a steering amount detecting means for detecting a steering angle θH (vehicle steering amount) of the steering wheel, 10 is a master cylinder, 11 is an engine, 12 is
Reference numeral denotes an automatic transmission (AT), and reference numeral 13 denotes an EGI controller that adjusts a fuel injection amount according to the rotation speed of the engine 11, the amount of intake air, and the like.

As shown in FIG. 2, the brakes 2, 2... Of the right front wheel 21FR and the brake 2 of the left rear wheel 21RL are connected to the master cylinder 10 via a first hydraulic line 22a. On the other hand, the brake 2 of the left front wheel 21FL and the brake 2 of the right rear wheel 21RR are connected to the master cylinder 10 by a second hydraulic line 22b different from the first hydraulic line 22a. Two independent brake systems of the piping type are configured. Then, the wheels 21FR, 21FL,.
Is applied with a braking force.

The pressurizing unit 3 includes the first and second pressure units.
Hydraulic pumps 31a, 31b connected to the hydraulic lines 22a, 22b, respectively, and these hydraulic pumps 31a, 31b
b and cut valves 32a and 32b respectively provided in the first and second hydraulic lines 22a and 22b so that the master cylinder 10 can be connected and disconnected, and the cut valves 32a and 32b and the master cylinder 10 And a hydraulic pressure sensor 33 for detecting the hydraulic pressure between the two. And
The cut valves 32a and 32b are closed in response to a command from the SCS controller 5, whereby the hydraulic fluid discharged from the hydraulic pumps 31a and 31b is transferred via the HU4 regardless of the brake operation by the driver. Are supplied to the brakes 2, 2,.
As shown in FIG. 2, the HU 4 is provided with pressurizing valves 41, 41,... For pressurizing the brakes 2 with pressurized liquid supplied via the first hydraulic line 22a or the second hydraulic line 22b.
, And pressure reducing valves 43 connected to the reservoir tank 42 to reduce the pressure. The opening degree of each of the pressurizing valve 41 and each of the pressure reducing valves 43 is adjusted to increase or decrease according to a command from the SCS controller 5, so that the hydraulic pressure applied to each of the brakes 2 is increased or decreased, and the braking force is increased or decreased. It is configured to be changed.

The SCS controller 5 controls the operation of the pressurizing unit 3 and the HU 4 to independently apply a braking force to the front, rear, left and right wheels 21 to impart a required yaw moment to the vehicle 1. Thereby, the turning posture of the vehicle 1 is controlled so as to converge toward the target traveling direction. Specifically, the SCS controller 5
As shown in FIG. 3, the vehicle includes a state quantity calculation unit 51, a target state quantity calculation unit 52, a control intervention determination unit 53, a yaw rate control unit 54, and a sideslip angle control unit 55. The turning posture of the vehicle 1 is determined based on input signals from the speed sensors 6, 6,..., The lateral G sensor 7, the yaw rate sensor 8, and the steering angle sensor 9, and the pressure unit 3 and the HU 4 It is configured to perform operation control (SCS control). Further, the SCS controller 5
Detects a driver's brake operation based on an input signal from the hydraulic pressure sensor 33, and controls the operation of the pressurizing unit 3 and the HU 4 in response to the brake operation.

The state quantity calculation unit 51 is configured to control the vehicle 1 in the traveling direction of the vehicle 1 based on input signals from the wheel speed sensors 6, 6,..., The lateral G sensor 7, the yaw rate sensor 8, and the steering angle sensor 9. As the vehicle state quantity representing the turning posture,
The vehicle side slip angle β and the vehicle speed Vscs generated in the vehicle 1 are configured to be detected by calculation, and the target state amount calculation unit 52 similarly calculates the target side slip angle corresponding to the target travel direction. It is configured to calculate βTR and target yaw rate ψ′TR. Further, the control intervention determination unit 53 determines whether the slip angle deviation between the detected sideslip angle β and the target sideslip angle βTR and the detected yaw rate ψ ′ detected by the yaw rate sensor 8 and the target yaw rate ψ′TR. The yaw rate deviation amount is calculated, and the SCS control intervention determination is performed based on these sideslip angle deviation amount and yaw rate deviation amount.

The yaw rate control section 54 applies a relatively small yaw moment to the vehicle 1 so that the detected yaw rate ψ 'converges to the target yaw rate ψ'TR, thereby changing the vehicle attitude by the driver's driving operation (mainly, the steering operation). The yaw rate control is performed so as to smoothly change to follow the steering angle), and the side slip angle control unit 55 applies a relatively large yaw moment to the vehicle 1 to thereby control the vehicle side slip angle β. Is the target sideslip angle β
The skid angle control for quickly correcting the turning posture of the vehicle 1 so as to converge to TR is performed.

Further, the SCS controller 5 has a rough road determination control unit 56.
Determines whether or not the traveling road surface of the vehicle 1 is a rough road based on a change rate such as a vertical load or a wheel slip ratio calculated by the state quantity calculating unit 51 as described later. When the determination is made, as will be described later, the control is performed differently from when the road is not a bad road.

The SCS controller 5 has an SCS
In addition to control, the well-known ABS (Anti-Skid Brake
System) Control and TCS (Traction Control System)
The ABS also controls the wheels 21FR,
This system limits the braking force applied to these wheels 21FR, 21FL,... In order to prevent the brake lock of 21FL,. This is a system to prevent slippage.

FIG. 4 shows an outline of basic control by the SCS controller 5. In this basic control, first, the driver operates the vehicle 1
Get on the ignition key and turn on the ignition key.
In step SA1, initialization of the SCS controller 5 and the EGI controller 13 is performed, and the calculated values and the like stored in the previous processing are cleared. In step SA2, after the origin correction of the wheel speed sensors 6, 6,... Is performed, signal input to the SCS controller 5 is performed from each of these sensors, and based on these input signals, the vehicle A common vehicle state quantity such as vehicle speed, vehicle deceleration, and vehicle speed at each wheel position is calculated.

Subsequently, an SCS control operation is performed in step SA4. That is, in step SA41, the SCS vehicle speed Vscs, the vehicle side slip angle β, the wheel slip ratio and slip angle of each wheel, the vertical load of each wheel, the tire load factor, and the road surface friction coefficient μ are calculated. The yaw rate ψ'TR and the target side slip angle βTR are calculated. Then, in step SA43, an intervention is determined for the yaw rate control or the side slip angle control based on the above calculation result. This step S
In A44, the wheels 21FR, 21FL,.
And the braking force to be applied to each of the selected wheels 21 is calculated. Then, based on the calculated braking force, in step SA45, the control output amount to the pressurizing unit 3 and the HU4, that is, the pressurizing valve 4 of each brake 2
, And the respective valve openings of the pressure reducing valves 43, 43,... Are calculated.

Further, in step SA5, a control target value and a control output amount necessary for the ABS control are calculated, and step S5 is performed.
In A6, a control target value and a control output amount required for the TCS control are calculated, and then, in step SA7, the respective calculation results of the ABS control, the TCS control, and the SCS control are arbitrated by a predetermined method, and the pressurization is performed. The control output amount to the unit 3 and the HU 4 is determined. Then, in step SA8, the pressure units 3 and HU4 are operated to control the degree of opening of each of the pressure valves 41 and the pressure reduction valves 43.
The brakes 2, 2, ... of the wheels 21FR, 21FL ...
Control the hydraulic pressure supplied to the wheels 21FR, 21FL
The required braking force is applied to. Finally, step SA9
Perform a fail-safe determination as to whether or not the wheel speed sensors 6, 6,... And the pressurizing unit 3 are operating normally, and return.

In the above flowchart, step SA41 corresponds to the state quantity calculating section 51, SA42 corresponds to the target state quantity calculating section 52, step SA43 corresponds to the control intervention determining section 53, and step SA44 and step SA45 correspond to each other. , The yaw rate control unit 54 and the sideslip angle control unit 55.

-Description of SCS Control Calculation- Hereinafter, the details of the SCS control calculation in step SA4 will be described with reference to FIGS. Note that the ABS control calculation in step SA5 and the TC control in step SA6
Since the S control calculation is well known, its description is omitted.

FIG. 5 shows the vehicle speed Vscs, the vehicle side slip angle β, the vertical load, the wheel slip ratio, the wheel slip angle, the tire load ratio, and the road surface friction coefficient μ obtained by the state quantity calculator 51 in step SA41 in FIG. The calculation and the calculation of the target side slip angle βTR and the target yaw rate ψ′TR by the target state quantity calculation unit 52 in step SA42 of FIG. That is, in step SB2, the wheel speed v1 of the wheel 21FR, the wheel speed v2 of the wheel 21FL, the wheel speed v3 of the wheel 21RR, the wheel speed v4 of the wheel 21RL, the lateral acceleration y ″ of the vehicle 1, and the yaw rate of the vehicle 1 'And the steering angle θH of the steering wheel.
The vehicle speed Vscs is calculated based on the wheel speeds v1, v2,..., And in step SB6, the wheel speeds v1, v2,.
The vertical weight at each wheel position is calculated based on the vehicle speed Vscs, the wheel speeds v1, v2,..., And the lateral acceleration y ″. The vehicle side slip angle β is calculated based on the yaw rate ψ ′ and the steering angle θH.

Subsequently, in step SB10, the slip rate of each wheel 21 is determined based on the wheel speeds v1, v2,..., The vehicle speed Vscs, the vehicle side slip angle β, the yaw rate ψ ', and the steering angle θH. In step SB12, based on the vertical load at each wheel position and the slip ratio and the slip angle, the wheels 21FR,
For each of 21FL, ..., tires 23, 23, ...
Is calculated, which is the ratio of the current gripping force to the total gripping force that can be exerted. Then, Step SB1
In step SB16, a road friction coefficient μ is calculated based on the load factor and the lateral acceleration y ″. In step SB16, the road friction coefficient μ, the vehicle speed Vscs, and the steering angle θH are calculated.
Target yaw rate ψ′TR and target sideslip angle βTR
Is calculated.

FIG. 6 shows the SCS control after the SCS control intervention determination in step SA43 of FIG. 4. In step SB18, the yaw rate deviation amount (| ψ′TR−) between the yaw rate ψ ′ and the target yaw rate ψ′TR ψ '|), and
The side slip angle deviation amount (| βTR−β |) between the vehicle side slip angle β and the target side slip angle βTR is determined by the yaw rate control unit 54 in advance to determine the yaw rate control intervention. Compare with thresholds K1 and K2. If the yaw rate deviation amount is equal to or greater than the intervention determination threshold value K1 or the side slip angle deviation amount is equal to or greater than the intervention determination threshold value K2, the deviation of the vehicle attitude with respect to the target traveling direction increases. Yes S
It is determined that CS control intervention is necessary, and step SB20 is performed.
On the other hand, if the yaw rate deviation amount is smaller than the yaw rate control intervention determination threshold value K1 and the side slip angle deviation amount is smaller than the intervention determination threshold value K2, the SCS control It is determined that no intervention is necessary, and the process returns to step SB2.

Subsequently, in step SB20, the side slip angle deviation amount (| βTR−β |) is determined by the side slip angle control unit 55 to determine a side slip angle control intervention determination which is set in advance for the side slip angle control intervention determination. Compare with the value K3 (K3> K2). If the side slip angle deviation is smaller than the intervention determination threshold value K3, the process proceeds to step SB22 to set the target yaw rate ψ'TR as the SCS control target value, and then proceeds to step SB24 to execute the actual SCS control. Is calculated mainly based on the yaw rate deviation amount (| ψ′TR−ψ ′ |). That is, while it is determined that the change in the vehicle attitude is relatively small and in a stable state (SB20), the vehicle is controlled so that the yaw rate ψ ′ of the vehicle 1 converges to the target yaw rate ψ′TR corresponding to the driving operation of the driver. A relatively small yaw moment is applied to the motor 1 (SB22, 24), whereby yaw rate control for smoothly changing the vehicle posture so as to follow the driving operation of the driver is performed.

On the other hand, if the side slip angle deviation amount (| βTR−β |) is equal to or larger than the side slip angle control intervention determination threshold value K3 in step SB20, the process proceeds to step SB26, where the target side slip angle βTR is subjected to SCS control. The target value is set as the target value, and thereafter, the process proceeds to step SB28, where the SCS control amount βamt actually used for the SCS control is set to the side slip angle deviation amount (| βTR−
β |). That is, when it is determined that the vehicle attitude is largely collapsed (SB20), the vehicle 1 is controlled so that the vehicle sideslip angle β converges to the target sideslip angle βTR.
A relatively large yaw moment is applied to the vehicle (SBs 26 and 28), whereby the side slip angle control for quickly correcting the vehicle attitude is performed.

Then, in step SB30 following step SB24 or step SB28, it is determined whether or not a failure has occurred in the pressurizing unit 3 or the HU4. If it is determined that a failure has occurred, the process proceeds to step SB32. The SCS control is stopped and the process returns. On the other hand, if the failure is not determined in step SB30, the process proceeds to step S30.
Proceeding to B34, the above SCS control, ABS control and TC
The calculation results of the S control are arbitrated by a predetermined method. An outline of the arbitration will be described. If the ABS control is performed when the SCS control is performed, the AB control is performed.
By correcting the S control amount based on the SCS control amount ψ′amt or βamt, the SCS control is performed while giving priority to the ABS control. When the SCS control is performed, the TCS control is performed. If so, its T
The operation of the pressurizing unit 3 and the HU 4 for CS control is stopped, and SCS control is performed.

Subsequently, at step SB36, SC
Wheels 21FR and 21FL that apply braking force for S control,
... and select these wheels 21FR, 21FL,
Are calculated based on the SCS control amount ψ′amt or βamt. If the yaw rate control increases the yaw rate ψ ′ of the vehicle 1 clockwise in the yaw rate control, and attempts to turn the turning posture of the vehicle 1 toward the right side in the sideslip angle control, the wheel selection and the calculation of the braking force will be outlined. In this case, the SCS control amount ψ'amt is applied to the right front wheel 21FR or the right front and rear wheels 21FR and 21RR.
Alternatively, the vehicle 1 is provided by applying a braking force according to βamt.
The clockwise yaw moment is applied to the motor. Conversely, when the yaw rate ψ ′ of the vehicle 1 is increased counterclockwise, and when the turning posture of the vehicle 1 is directed to the left side, the left front wheel 21FL or the left front wheel 2FL
For 1FL and 21RL, the SCS control amount ψ'amt or β
A counterclockwise yaw moment is applied to the vehicle 1 by applying a braking force according to amt. And those selected wheels 21FR, 21FL, ...
, A control output amount to the pressurizing unit 3 and the HU 4 for applying a desired braking force (final control amount for applying a yaw moment to the vehicle 1), that is, a pressurizing valve for the brakes 2, 2,. , 41, 41,... And the pressure reducing valves 43, 43,.
Computation is performed in B38, and the computed control output amounts are outputted to the pressurizing unit 3 and HU4 in step SB40, and the SCS control is executed, and the process returns.

Note that an upper limit value is set for the control output amount, so that a braking force exceeding the upper limit value is not applied to each wheel 21, especially when the traveling road surface of the vehicle 1 is not a rough road. Thus, the vehicle posture is prevented from becoming unstable due to excessive braking force.

FIG. 7 shows the control operation of the rough road determination control unit 56 of the SCS controller 5, which determines whether or not the traveling road surface of the vehicle 1 is a rough road, and determines that the road is rough. In addition, control is performed such that the control amount of the turning posture control of the vehicle 1 (the control output amount) is set to be larger than that when it is determined that the vehicle 1 is not a rough road.

That is, first, at step SC1, the vehicle 1
It is determined whether or not the traveling road surface is a rough road. This determination is made based on, for example, the vertical load obtained in step SB6 or the rate of change of the wheel slip ratio obtained in step SB10, and if these are greater than a predetermined value, it is determined that the road is bad. When the determination in step SC1 is NO, the process returns. That is, when the traveling road surface is not a rough road, the following control is not performed, and the SC
S control is performed.

On the other hand, if the determination in step SC1 is YES, the process proceeds to step SC2, where the degree of rough road, the steering angle θ
The upper limit value is set from a map of the upper limit value of the control output amount (braking force) determined in advance according to H and the steering angular velocity θH ′ which is the rate of change of the steering angle θH obtained from the steering angle θH. The upper limit value is set to be larger than that when the road is not a rough road. Therefore, as described above, even if the control output amount is limited by the upper limit when the traveling road surface is not a rough road, the upper limit value is set to a low value. In the case of a road, the control output amount is set to be large by increasing the upper limit value. The upper limit value of the control output amount is constant when the traveling road surface is not a rough road, but when the traveling road surface is a rough road, the degree of the rough road (the degree of change in the vertical load or the wheel slip rate), steering, etc. The larger the angle θH and the steering angular velocity θH ', the larger the value. For this reason, this upper limit value is smaller in a region where the steering angle θH is small than in a region where the steering angle θH is large.

In the next step SC3, the above step S
At B18, the yaw rate control intervention threshold values K1 and K2 for determining whether or not to perform the yaw rate control are set to be larger than those when the traveling road surface is not a rough road. As a result, the rate at which the yaw rate deviation amount and the sideslip angle deviation amount are equal to or more than the yaw rate control intervention thresholds K1 and K2, respectively, is reduced, and the yaw rate control in the yaw rate control unit 54 is suppressed.

Subsequently, at step SC4, at steps SB24 and SB28, the SCS control amount ψ'amt
, Βamt, control gain or step SB
At 38, in order to set a large control gain for obtaining the control output amount, one of the control gains is set to be 20% larger than when the traveling road surface is not a rough road. Then, in the next step SC5, as the yaw rate control intervention threshold value K2 is increased in the above step SC3, the side slip angle control intervention threshold value K3 is also increased to suppress the side slip angle control in the side slip angle control unit 55. And return. Thereafter, the SCS control of the vehicle 1 is performed as described above while maintaining the state set in steps SC2 to SC5. When the determination in step SC1 returns NO, the state set in steps SC2 to SC5 is canceled and the state returns to the initial state.

In the control procedure of the rough road determination control section 56, the rough road determination means 61 for determining whether or not the traveling road surface of the vehicle 1 is a rough road is determined in step SC1, and the rough road determination means 61 is determined in steps SC2 and SC4. When the rough road determination unit 61 determines that the traveling road surface is a rough road, the control amount variable unit 62 that sets the control output amount to be larger than that when it is determined that the road is not a rough road further includes a step SC3 that includes:
Yaw rate control suppression means 63 for suppressing the yaw rate control by the yaw rate control unit 54 when the traveling road surface is determined to be a bad road by the bad road determination means 61 are respectively constituted.

Therefore, in this embodiment, when the rough road determination control unit 56 determines that the traveling road surface of the vehicle 1 is a rough road, the upper limit value of the control output amount and the SCS control amount ψ '
The control gain for obtaining amt, βamt or the control output amount is set to be larger than that when the road is not a bad road. Therefore, the wheels 21FR, 21FL, 21FL,
.. Are given a large braking force, so that a large yaw moment can act on the vehicle 1. As a result,
The turning posture of the vehicle 1 can be changed early against the unevenness of the road surface, and fine-grained posture control corresponding to a drastic change in the road surface condition can be performed. At this time,
Since the friction coefficient of the road surface is usually smaller than when the road is not rough, if the braking force is too large, the wheels 21FR, 21FL,... In this case, since the wheels 21FR, 21FL,... Are more likely to stumble on unevenness of the road surface due to locking, the detected vehicle state quantity can be quickly converged to the target vehicle state quantity. Conversely, even if the deviation amount between the detected vehicle state quantity and the target vehicle state quantity sharply increases due to the wheels 21FR, 21FL,... Can be returned to. Moreover, even on a rough road, even if the control output amount is increased, the driver hardly feels a sense of incongruity due to the attitude control, and the traveling speed of the vehicle 1 is low, so that even if the wheels 21FR, 21FL,. It is unlikely to be unstable. Therefore, even when the traveling road surface is a rough road, the turning posture of the vehicle 1 can be effectively controlled as in the case of a flat pavement road, etc., resulting in insufficient posture change on a rough road and wheel stumbling. The accompanying excessive change in posture can be prevented.

If it is determined that the traveling road surface of the vehicle 1 is a rough road, the yaw rate control intervention thresholds K1, K2 and the side slip angle control intervention threshold K3 are set to be large, and the yaw rate control unit 54 and the sideslip Since the yaw rate control and the sideslip angle control in the angle control unit 55 are respectively suppressed,
Control is no longer performed in response to a change in vehicle turning posture due to the effect of kickback of wheels due to unevenness of the road surface, and such control can be prevented from destabilizing the vehicle turning posture. In particular, even if the yaw rate control that can be changed so as to follow the driving operation of the driver is suppressed, the movement is irrelevant to the driving operation of the driver. be able to. On the other hand, even on a rough road, when the yaw rate deviation amount and the side slip deviation amount are considerably large, the wheels 21F
Since the attitude change of the vehicle 1 is excessively large due to a stumble of R, 21FL, etc., it is worth performing yaw rate control or side slip angle control. In such a case, the yaw rate control or side slip angle control is performed. Then, the control output amount becomes large, so that the vehicle turning posture can be converged to the target traveling direction early. Therefore, it is possible to prevent an excessive change in the attitude of the vehicle 1 while preventing problems due to the yaw rate control and the side slip angle control on a rough road.

Further, the upper limit value of the control output amount is the steering angle θH.
The steering angle θH ′ and the steering angular velocity θH ′ are set to be larger as the steering angle θH ′ is larger, and are set smaller in a region where the steering angle θH is smaller than in a region where the steering angle θH is larger.
Is large, the attitude of the vehicle 1 can be largely changed by increasing the control output amount so as to correspond to the driver's operation of turning the vehicle 1. On the other hand, in the region where the steering angle θH is small, the vehicle 1 is traveling almost straight, although there is a small change in attitude, so there is no problem even if the control output amount is reduced. On the contrary, the posture may be unstable. Therefore, stable attitude control can be performed while respecting the driver's intention.

In the above-described embodiment, when it is determined that the traveling road surface of the vehicle 1 is rough, the yaw rate control intervention thresholds K1 and K2 are increased to increase the yaw rate control unit 54.
Although the yaw rate control in the above is suppressed, the yaw rate control may be prohibited and only the sideslip angle control in the sideslip angle control unit 55 may be performed. By doing this,
Since the sideslip angle control allows the turning posture of the vehicle 1 to converge to the target traveling direction earlier, an excessive change in the posture of the vehicle 1 can be more effectively prevented.

[0054]

As described above, according to the first aspect of the present invention, by applying a braking force to each wheel independently, the detected vehicle state quantity becomes equal to the target vehicle state quantity corresponding to the target traveling direction. For an attitude control device including attitude control means for controlling the turning attitude of the vehicle so as to converge, it is determined whether or not the traveling road surface of the vehicle is a rough road, and when it is determined that the road is rough, The control amount of the turning posture control of the vehicle by the posture control means is made larger than when it is determined that the vehicle is not on a rough road, thereby preventing a posture change insufficient on a rough road and an excessive posture change due to a wheel trip. Can be achieved.

According to the second aspect of the present invention, when it is determined that the traveling road surface is a rough road, the yaw rate control by the attitude control means is suppressed, thereby preventing problems due to the yaw rate control on the rough road. Excessive posture change of the vehicle can be prevented.

According to the third aspect of the present invention, the control gain for obtaining the control amount based on the deviation amount between the detected vehicle state amount and the target vehicle state amount is increased, so that the control amount is increased. Means are easily obtained,
The attitude control can be performed finely in response to a remarkable change in the road surface condition.

According to the fourth aspect of the present invention, the control amount is set to increase as the steering amount of the vehicle increases. In the invention of claim 6, the control amount is set to be larger as the steering amount change rate is larger. Therefore, according to these inventions, it is possible to perform attitude control that respects the driver's intention.

According to the fifth aspect of the present invention, the control amount is set smaller in the region where the steering amount of the vehicle is small than in the region where the steering amount is large, so that the attitude control can be stabilized.

According to the seventh aspect of the present invention, by increasing the preset upper limit value of the control amount, it is possible to easily obtain specific means for increasing the control amount, and to control the vehicle attitude control. Stabilization can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a vehicle to which a vehicle attitude control device according to an embodiment of the present invention is applied.

FIG. 2 is a diagram showing a hydraulic system of a brake.

FIG. 3 is a block diagram illustrating a configuration of an SCS controller.

FIG. 4 is a flowchart showing an outline of a control procedure by the SCS controller.

FIG. 5 is a flowchart illustrating a control procedure in a state quantity calculation unit and a target state quantity calculation unit.

FIG. 6 is a flowchart showing details of a control procedure after a control intervention determination by the SCS controller.

FIG. 7 is a flowchart illustrating a control procedure in a rough road determination control unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Brake (braking means) 3 Pressure unit (braking means) 4 Hydraulic unit (braking means) 5 SCS controller (attitude control means) 6 Wheel speed sensor (vehicle state detecting means) 7 Lateral G sensor (vehicle state detection) Means) 8 yaw rate sensor (vehicle state detecting means) 9 steering angle sensor (vehicle state detecting means) (steering amount detecting means) 21FR, 21FL, 21RR, 21RL wheels 51 state quantity calculating section (vehicle state detecting means) 52 target state quantity Calculation unit 54 Yaw rate control unit 56 Rough road determination control unit 61 Rough road determination unit 62 Control amount variable unit 63 Yaw rate control suppression unit β Vehicle side slip angle (Vehicle state amount) ψ ′ Yaw rate (Vehicle state amount) θH Steering angle (Vehicle steering) Amount) θH ′ Steering angular velocity (steering amount change rate) K1, K2 Yaw rate control intervention threshold

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tetsuya Tachihata 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd.

Claims (7)

[Claims] 1. A braking means configured to be capable of individually applying a braking force to each of front, rear, left and right wheels of a vehicle, a vehicle state detecting means for detecting a vehicle state quantity representing a turning posture of the vehicle with respect to a traveling direction, The operation of the braking means is controlled so that the braking force is applied to each of the wheels independently so that the detected vehicle state quantity detected by the vehicle state detecting means converges to the target vehicle state quantity corresponding to the target traveling direction. A posture control device for controlling the turning posture of the vehicle by providing the vehicle; a rough road determination device for determining whether a traveling road surface of the vehicle is a rough road; Control amount varying means for setting the control amount of the turning attitude control of the vehicle by the attitude control means to be larger than when it is determined not to be a rough road, when the traveling road surface is determined to be a rough road by the determination means; With Attitude control device for a vehicle according to claim Rukoto. 2. The vehicle attitude control device according to claim 1, wherein the vehicle state detection means is configured to detect at least a yaw rate occurring in the vehicle, and the attitude control means is detected by the vehicle state detection means. The yaw rate control for controlling the turning attitude of the vehicle by operating the braking means so that the detected yaw rate converges to the target yaw rate is performed at least, and the rough road determination means determines that the traveling road surface is a rough road. And a yaw rate control suppression means for suppressing the yaw rate control by the attitude control means when the vehicle is in a vehicle. 3. The vehicle attitude control device according to claim 1, wherein the control amount variable means increases a control gain for obtaining a control amount based on a deviation amount between the detected vehicle state amount and the target vehicle state amount. An attitude control device for a vehicle, wherein the attitude control apparatus is configured as described above. 4. The vehicle attitude control device according to claim 1, further comprising: a steering amount detection unit configured to detect a steering amount of the vehicle by a driver, wherein the control amount variable unit includes a steering amount detected by the steering amount detection unit. The vehicle attitude control device is configured to set the control amount to be larger as the value of the vehicle is larger. 5. The vehicle attitude control device according to claim 1, further comprising steering amount detection means for detecting a steering amount of the vehicle by the driver, wherein the control amount variable means includes a steering amount detected by the steering amount detection means. A vehicle attitude control device characterized in that a control amount is set smaller in a region where is smaller than in a region where it is large. 6. The vehicle attitude control device according to claim 1, further comprising a steering amount change rate detecting means for detecting a change rate of a steering amount of the vehicle by a driver, wherein the control amount variable means detects the steering amount change rate. A vehicle attitude control device characterized in that the control amount is set to be larger as the steering amount change rate detected by the means is larger. 7. The vehicle attitude control device according to claim 1, wherein the control amount varying means is configured to increase a preset upper limit value of the control amount. Vehicle attitude control device.