JPH09123889A - Vehicular behavior control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the behavior of a vehicle from contrarily worsening as a result of the implementation of behavior control by prohibiting the control, when an auxiliary steering device such as a rear wheel steering device is abnormal. SOLUTION: This device is equipped with a rear wheel steering device, and a behavior control device for estimating the behavior of a vehicle at steps 20 to 50, and stabilizing the behavior by controlling the brake force of each wheel at steps 110 to 160 on the basis of the estimated behavior. In addition, judgement is made as to whether the rear wheel steering device is normal, and behavior control with the behavior control device is prohibited, when an error occurs in the rear wheel steering device, disabling normal rear wheel steering.

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 behavior such as spin and drift out when a vehicle such as an automobile turns.

[0002]

2. Description of the Related Art As one of behavior control devices for controlling the behavior of a vehicle such as an automobile having a rear wheel steering device and a braking / driving force control device, for example, as described in JP-A-4-2557, 2. Description of the Related Art A behavior control device configured to set the sensitivity of braking / driving force control higher than the sensitivity of rear wheel steering as the longitudinal acceleration of the vehicle increases is conventionally known.

According to this behavior control device, when the longitudinal acceleration of the vehicle is large, the change in the slip ratio of each wheel is suppressed to be small due to the change in the wheel load caused by the steering of the rear wheels. Therefore, compared to the case where such control is not performed, the total control effect of the rear wheel steering and the braking / driving force control can be enhanced and the behavior of the vehicle can be stabilized.

[0004]

Behavior control by braking / driving force control performed in a vehicle having a rear wheel steering system is as follows.
Steering performance (behavior characteristics) when the rear wheel steering system is normal
The behavior of the vehicle is estimated on the basis of the above, and it is performed based on the estimation result. However, if the rear wheel steering system becomes abnormal, the steering performance will not be normal either. Therefore, if the behavior control is executed in the abnormal state of the rear wheel steering system, the behavior of the vehicle may worsen. In particular, when the behavior of the vehicle is estimated based on the parameter including the steering angle, the behavior cannot be estimated normally, and this problem becomes remarkable.

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 that the auxiliary steering device such as the rear wheel steering device is abnormal. By preventing the behavior control from being performed, it is possible to prevent the behavior of the vehicle from being worsened by the execution of the behavior control.

[0006]

SUMMARY OF THE INVENTION According to the present invention, the above-mentioned main problem is to achieve the structure of claim 1, namely, auxiliary steering means,
In a vehicle behavior control device having a behavior control means for stabilizing the behavior of the vehicle by controlling the braking force of each wheel based on the estimated behavior of the vehicle, when an abnormality occurs in the auxiliary steering means, This is achieved by a vehicle behavior control device characterized in that it has means for prohibiting the behavior control by the behavior control means.

According to this structure, when an abnormality occurs in the auxiliary steering means and the steering performance is not normal, the behavior control by the behavior control means is prohibited, so that the behavior of the vehicle is rather deteriorated by the execution of the behavior control. Is reliably prevented.

[0008]

According to a preferred embodiment of the problem solving means of the present invention, in the structure of claim 1, there is provided means for estimating a side slipping state of the vehicle, and the braking force control means is the vehicle. When the skid condition is estimated, the skid condition is controlled by controlling the braking force of each wheel.

According to another preferred aspect of the means for solving the problems of the present invention, in the structure of claim 1, the auxiliary steering means controls the actual steering angle of the rear wheels to a target steering angle. The steering device is configured to determine that the rear wheel steering device is abnormal when the magnitude of the deviation between the target steering angle and the actual steering angle of the rear wheels exceeds a predetermined value.

[0010]

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.

Referring to 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 depression of a brake pedal 12, and an oil pressure in the master cylinder. And a hydro booster 16 for increasing the brake oil to a pressure (regulator pressure) corresponding to the above. Master cylinder 1
The first port 4 is a brake hydraulic control conduit 18 for the front wheels.
The brake hydraulic control devices 20 and 22 for the left and right front wheels
The second port is connected to a three-port two-position switching type electromagnetic control valve 28 for the right and left rear wheels by a rear wheel brake hydraulic control conduit 26 having a proportional valve 24 on the way. 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 braking device 10 also has an oil pump 40 that pumps the brake oil stored in the reservoir 36 and supplies it as high-pressure oil to the high-pressure conduit 38. The high-pressure conduit 38 is connected to the hydrobooster 16 and the switching valve 44, and an accumulator 46 for accumulating high-pressure oil discharged from the oil pump 40 as accumulator pressure is connected to the middle of the high-pressure conduit 38. There is. As shown in the drawing, the switching valve 44 is also a 3-port 2-position switching type electromagnetic switching valve, and is connected to the hydrobooster 16 by a regulator pressure supply conduit 47 for four wheels.

The brake hydraulic control devices 20 and 22 for the front left and right wheels are wheel cylinders 48FL and 48FR for controlling the braking force on the corresponding wheels, electromagnetic control valves 50FL and 50FR of a 3-port 2-position switching type, and a reservoir. Low pressure conduit 5 as return passage connected to 36
2 and the switching valve 44. The normally open electromagnetic on-off valves 54FL and 54FR and the normally closed electromagnetic on-off valve 56FL provided in the middle of the regulator pressure supply conduit 53 for the left and right front wheels. And 56 FR. Open / close valve 5
The regulator pressure supply conduits 53 for the left and right front wheels between the 4FL, 54FR and the on-off valves 56FL, 56FR are connected conduits 58FL, 5FL.
It is connected to the control valves 50FL and 50FR by 8FR.

A brake hydraulic control device 32 for the 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 connection conduits 66RL and 66RR, respectively.

The control valves 50FL and 50FR are respectively the brake hydraulic pressure control conduit 18 for the front wheels and the 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 switching valve 44 and the left and right rear wheel control valve 28, and the control valve 28 and the brake hydraulic pressure control conduit 26 for the rear wheels, respectively. The on-off valves 60RL and 60RR are connected in communication with each other, and the on-off valves 60RL and 60RR and the regulator pressure supply conduit 68 are connected.
The first position shown in the figure for shutting off the communication with the brake hydraulic pressure control conduit 26, shutting off the communication between the brake hydraulic pressure control conduit 26 and the on-off valves 60RL, 60RR, and the on-off valves 60RL, 60RR and the regulator pressure supply conduit 6.
It is adapted to switch to a second position where 8 is connected for communication.

The control valves 50FL, 50FR, 28 function as master cylinder pressure shutoff valves, and when these control valves are in the first position shown, the wheel cylinders 48FL, 48.
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 valve 44 is a wheel cylinder 48F.
The control valves 50FL, 50FR, 28 are switched to the second position and the opening / closing valves 54FL, 54FR serve to switch the hydraulic pressure supplied to the L, 48FR, 64RL, 64RR between the accumulator pressure and the regulator pressure. , 60RL, 60RR and the on-off valves 56FL, 56FR, 62RL, 62RR in the positions shown, when the switching valve 44 is maintained in the first position shown, the wheel cylinders 48FL, 48FR, 64R.
By supplying the regulator pressure to L and 64RR, the pressure in each wheel cylinder is controlled by the regulator pressure, so that the braking pressure of that wheel becomes the depression amount of the brake pedal 12 regardless of the braking pressure of the other wheels. It is controlled in the pressure increasing mode by the corresponding regulator pressure.

Even if each valve is set 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 drops.

Further, the control valves 50FL, 50FR, 28 are switched to the second position and the opening / closing valves 54FL, 54FR, 60RL,
When the switching valve 44 is switched to the second position with the 60RR and the on-off valves 56FL, 56FR, 62RL, 62RR in the positions shown, the wheel cylinders 48FL, 48FR, 64R.
By supplying the accumulator pressure to L and 64RR, the pressure in each wheel cylinder is controlled by the accumulator pressure higher than the regulator pressure, and thereby, regardless of the depression amount of the brake pedal 12 and the braking pressure of other wheels. The braking pressure of the wheels 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, 62RR are controlled to the illustrated state, the pressure in each wheel cylinder is maintained regardless of the position of the switching valve 44, and the control valves 50FL, 50FR, 28 are switched to the second position. Open / close valves 54FL, 54FR, 6
0RL, 60RR and open / close valves 56FL, 56FR, 62RL, 62
When RR is switched to the second position, the pressure in each wheel cylinder is reduced irrespective of the position of the switching valve 44, so that the wheel of that wheel is irrespective of the depression amount of the brake pedal 12 and the braking pressure of other wheels. The braking pressure is controlled in the pressure reduction mode.

Switching valve 44, control valves 50FL, 50FR, 2
8, the on-off valves 54FL, 54FR, 60RL, 60RR and the on-off valves 56FL, 56FR, 62RL, 62RR are controlled by the electric control device 70 as described in detail later. The electric control device 70 includes a microcomputer 72 and a drive circuit 74.
Although the microcomputer 72 is not shown in detail in FIG.
PU), read only memory (ROM), random access memory (RAM), and input / output port device, which are connected to each other by a bidirectional common bus. Good.

In the input / output port device of the microcomputer 72, 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, and a yaw rate sensor 80. A signal indicating the yaw rate γ of the vehicle body, a signal indicating the steering angle θf of the front wheels from the steering angle sensor 82, and a longitudinal acceleration G of the vehicle body from the longitudinal acceleration sensor 84 provided substantially at the center of gravity of the vehicle body.
A signal indicating x and wheel speeds (peripheral speeds) Vwfl and Vwf of the left and right front wheels and the left and right rear wheels from the wheel speed sensors 86FL to 86RR, respectively.
A signal indicating r, Vwrl, Vwrr and a signal indicating the actual steering angle δr of the rear wheels are input from the steering control device 90 that controls the rear wheel steering device 88. 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 being positive, and the longitudinal acceleration sensor 84 detects longitudinal acceleration with the accelerating direction of the vehicle being positive.

As shown schematically in FIG. 6, the rear wheel steering system 88 receives a left rear wheel 9 via tie rods 92RL and 92RR based on a control signal from a steering control system 90.
An actuator 96 for steering the 4RL and the right rear wheel 94RR is included. The steering control device 90 controls the vehicle speed V, the yaw rate γ, the steering angle θ of the front wheels (the front left wheel 94FL and the front right wheel 94FR).
The target steering angle δrt of the rear wheels is calculated based on f etc., and the actual steering angle δr of the rear wheels detected by the steering angle sensor 98 is the target steering angle δrt.
The actuator 96 is controlled so that The steering control device 90 uses the rear wheel steering device 88 as described later.
Is determined to be normal, and a signal (a flag Ff described later) indicating the determination result is output to the electric control device 70.

Further, the ROM of the microcomputer 72 stores the control flow of FIGS. 2 to 5 and the maps of FIGS. 8 to 12 as described later, and the CPU will be described later based on the parameters detected by the various sensors described above. As described above, various calculations are performed to obtain the spin state amount SS for determining the turning behavior of the vehicle, and the grip state index values Gγ and G
gy is determined, the side slippage state of the vehicle is determined based on the spin state amount and the grip state index value, and the braking force of each wheel is controlled based on the determination result to control the turning behavior.

Next, the turning behavior control routine of the vehicle will be described with reference to the flow chart 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. Further, in the flowchart shown in FIG. 2, the flag Ff relates to whether or not the rear wheel steering device 88 is abnormal, 1 indicates that the rear wheel steering device is abnormal, and flag F indicates the vehicle. Indicates whether or not the vehicle is in the non-grip state, and 1 indicates that the vehicle is in the non-grip state.

First, in step 10, the vehicle speed sensor 7
A signal or the like indicating the vehicle speed V detected in 6 is read, and in step 20, the lateral acceleration Gy is deviated from the product V * γ of the vehicle speed V and the yaw rate γ as a deviation Gy-V * γ. That is, the side slip acceleration Vyd of the vehicle is calculated, and in step 30, the side slip velocity Vy of the vehicle body is calculated by integrating the side slip acceleration Vyd.
The slip angle β of the vehicle body is calculated as the ratio Vy / Vx of the vehicle side slip velocity Vy to the vehicle longitudinal velocity Vx (= vehicle speed V).

In step 40, the spin amount SV is calculated as the linear sum K1 * β + K2 * Vyd of the vehicle body slip angle β and the lateral slip acceleration Vyd, where K1 and K2 are positive constants, respectively, and in step 50, the yaw rate is calculated. The turning direction of the vehicle is determined based on the sign of γ, and the spin state quantity SS is calculated as SV when the vehicle is turning left and as -SV when the vehicle is turning right, and the spin state is calculated when the calculation result is a negative value. The quantity is zero. The spin amount SV may be calculated as a linear sum of the vehicle body slip angle β and its differential value βd.

In step 55, it is judged whether or not the flag Ff is 1, that is, it is judged whether or not the rear wheel steering device 88 is abnormal. If a negative judgment is made, the routine proceeds to step 80. If the determination is affirmative, the process proceeds to step 60. In step 60, it is determined whether the flag F is 1, that is, whether the vehicle is in the non-grip state, and when a positive determination is made, in step 70, the spin state quantity is determined. The spin control amount Rsspin, which is the target slip ratio of the entire vehicle, is calculated from the map corresponding to the graph shown in FIG. 8 based on SS, and when a negative determination is made, the spin control amount Rsspin becomes 0 in step 80. Set.

In step 90, the spin control amount Rss
Whether or not the pin is 0, that is, whether or not the behavior of the vehicle is stable and behavior control is unnecessary is determined, and when a positive determination is made, each valve is checked in step 100. After returning to the normal position shown in 1, the process returns to step 10, and when a negative determination is made, in step 110, the front wheel on the outside of the turning side, the front wheel on the inside of the turning side,
Target slip ratios Rsfo of the turning outer rear wheel and the turning inner rear wheel,
Rsfi, Rsro, and Rsri are calculated.

## EQU00001 ## Rsfo = Rsspin Rsfi = 0 Rsro = -Rsspin / 2 Rsri = -Rsspin / 2

In step 120, the turning direction of the vehicle is determined based on the sign of the yaw rate γ to identify the inner and outer turning wheels, and the final target slip ratio Rsi (i = fr, fl, rr, rl) are calculated. That is, when the final target slip ratio Rsi is a left turn and a right turn of the vehicle, respectively,
Is required in accordance with

[0033]

Rsfr = Rsfo Rsfl = Rsfi Rsrr = Rsro Rsrl = Rsri

## EQU00003 ## Rsfr = Rsfi Rsfl = Rsfo Rsrr = Rsri Rsrl = Rsro

In step 130, the target wheel speed Vwti of each wheel is calculated according to the following equation 4 using Vb as the reference wheel speed (for example, the wheel speed of the front wheel on the inside of the turn).

## EQU4 ## Vwti = Vb * (100-Rsi) / 100

In step 140, Vwid is the wheel acceleration of each wheel (differential value of Vwi), and Ks is a positive constant coefficient, and the target slip amount SP of each wheel is calculated according to the following equation (5).
i is calculated, and in step 150, the duty ratio Dri of each wheel is calculated from the map corresponding to the graph shown in FIG.
Is calculated.

## EQU5 ## SPi = Vwi-Vwti + Ks * (Vwid-Gx)

Further, at step 160, the switching valve 44
Is switched to the second position to introduce the accumulator pressure, and the control signal is output to the control valves 28, 50FR to 50RL of the wheels corresponding to the wheels whose final target slip Rsi is not 0. The control valve is switched and set to the second position. Further, the control signal corresponding to the duty ratio Dri is output to the opening / closing valve of each wheel to control the supply / discharge of the accumulator pressure to / from the wheel cylinders 48FR to 48RL, thereby controlling the braking pressure of each wheel.

In this case, when the duty ratio Dri is a value between the negative reference value and the positive reference value, the upstream side opening / closing valve is switched to the second position and the downstream side opening / closing valve is set to the first position. By being held in the position, the pressure in the corresponding wheel cylinder is held, and when the duty ratio is equal to or greater than the positive reference value, the upstream and downstream on-off valves are controlled to the positions shown in FIG. The pressure in the wheel cylinder is increased by supplying the accumulator pressure to the corresponding wheel cylinder, and when the duty ratio is equal to or less than the negative reference value, the upstream and downstream opening / closing valves are in the second position. When the brake oil in the corresponding wheel cylinder is changed to the low pressure conduit 52,
To reduce the pressure in the wheel cylinder.

Next, the calculation routine for the estimated value μg of the friction coefficient of the road surface will be described with reference to the flow chart shown in FIG. The control according to the flowchart shown in FIG. 3 is executed by interruption every predetermined time.

First, at step 210, a signal indicating the lateral acceleration Gy of the vehicle detected by the lateral acceleration sensor 78 is read, and at step 220, an estimated value μg of the friction coefficient of the road surface is calculated. The horizontal acceleration Gxy of the vehicle is calculated according to the following equation 6.

[Equation 6] Gxy = (Gx ² + Gy ² ) ^1/2

In step 230, the horizontal acceleration Gxy
Is judged to have exceeded the horizontal acceleration Gxy (n-1) one cycle before. When a positive judgment is made, the coefficient K is set to 1 in step 240 and a negative judgment is made. Then, in step 250, the coefficient K is 0.
Set to 01. In step 260, the estimated value μg of the friction coefficient of the road surface is calculated according to the following equation 7.

(7) μg = (1−K) * μg (n-1) + K * Gxy

In the illustrated embodiment, the friction coefficient of the road surface is calculated as the square root of the sum of squares of Gx and Gy, but it may be estimated by the absolute value of the lateral acceleration Gy of the vehicle. , And the lateral acceleration components Gyfy at the front wheel position and the rear wheel position generated by yawing of the vehicle,
Gyry is calculated and these components and lateral acceleration G of the vehicle are calculated.
The lateral acceleration components Gyf and Gyr at the front wheel position and the rear wheel position are calculated as the sum of y, the larger value of Gyf and Gyr is calculated as the lateral acceleration Gys, and the square sum square root of Gx and Gys is calculated. Good.

Next, the flag F setting routine, that is, the vehicle grip state determination routine will be described with reference to the flow charts shown in FIGS. 4 and 5
The control according to the flowchart shown in FIG. 9 is also executed by interruption every predetermined time.

In step 310 of this routine, a signal indicating the steering angle θf is read, and step 3
In 20 and 330, the longitudinal velocity Vx (= V) of the vehicle
Based on the above, the low-speed processing coefficients Ka and Kb are calculated from the maps corresponding to the graphs shown in FIGS. 10 and 11, respectively.

In step 340, with N as the steering gear ratio and L as the wheel base, the first parameter corresponding to the deviation between the slip angle of the front wheels and the slip angle of the rear wheels, that is, the yaw rate γ, is calculated according to the following equation 8. Based on this, the steering angle deviation ΔSγ is calculated.

## EQU8 ## ΔSγ = {θf−δr * N− (N * L / Vx)
* Γ} * Ka

In step 350, the second parameter corresponding to the deviation between the slip angle of the front wheels and the slip angle of the rear wheels, that is, the steering angle deviation ΔSgy based on the lateral acceleration Gy is calculated in accordance with the following equation 9.

## EQU9 ## ΔSgy = {θf −δr * N− (N * L / Vx
² ) * Gy} * Kb

In step 360, the friction coefficient μg of the road surface calculated according to the flow chart shown in FIG.
The dead zone set value μgm is calculated from the map corresponding to the graph shown in FIG. 12 based on the above, and in step 370, the grip state index value Gγ based on the first parameter is calculated according to the following equation 10 using Kc as a positive constant. Is calculated. In step 380, the grip state index value Gγ
Is determined, and if a negative determination is made, the process proceeds to step 400 as it is, and if a positive determination is made, the grip state index value Gγ is set to 0 in step 390.

[Formula 10] Gγ = (| ΔSγ | −μgm) * Kc

In step 400, the grip state index value Ggy based on the second parameter is calculated according to the following equation 11 using Kd as a positive constant, and in step 400 it is determined whether the index value Ggy is negative. Is determined,
When the negative determination is made, the process proceeds to step 430 as it is, and when the positive determination is made, the index value Ggy is set to 0 in step 420. Dead band set value μ
Since gm has a larger value as the road friction coefficient μg is higher, the grip state index values Gγ and Ggy have smaller values as the road friction coefficient is higher.

[Equation 11] Ggy = (| ΔSgy | −μgm) * Kd

In step 430, it is determined whether or not the grip state index value Gγ exceeds the reference value Gγ1 (a positive constant), that is, whether or not the determination based on the first parameter is the non-grip state. If a determination is made and an affirmative determination is made, the flag F1 is set to 1 in step 440, and if a negative determination is made step 45.
At 0, the flag F1 is reset to 0.

In step 460, it is determined whether or not the grip state index value Ggy exceeds the reference value Ggy1 (a positive constant), that is, whether or not the determination based on the second parameter is the non-grip state. If a determination is made and a positive determination is made, the flag F2 is set to 1 in step 470, and if a negative determination is made step 48.
At 0, the flag F2 is reset to 0.

In step 490, the flag F1 is 1
And whether the flag F2 is 1 or not, that is, whether the determination based on the first parameter and the determination based on the second parameter are both in the non-grip state, a negative determination is made. When the determination is made, the routine proceeds to step 530, and when a positive determination is made, the count value C1 of the counter is incremented by 1 at step 500.

At step 510, the count value C1
Whether or not exceeds the reference value t1 (a positive constant),
That is, it is determined whether the state in which the non-grip state is determined by both the determination based on the first parameter and the determination based on the second parameter has continued for a predetermined time or longer, and a negative determination is performed. If this is the case, this routine is terminated as it is, and if a positive determination is made, the flag F is set to 1 in step 520.

At step 530, the count value C1
Is reset to 0, and it is determined in step 540 whether the flag F is 1 or not. If a negative determination is made, the process directly proceeds to step 570, and if an affirmative determination is made, the process proceeds to step 550. move on.

In step 550, the flag F1 is 0.
If a positive determination is made, the count value C2 of the counter is determined in step 560.
Is incremented by 1, and when a negative determination is made, the count value C2 is reset to 0 in step 570.

At step 580, the count value C2
Whether or not exceeds the reference value t2 (a positive constant),
That is, the state in which the non-grip state is determined by the determination based on the first and second parameters and then the determination that the grip state is performed by the determination based on the first parameter is continued for a predetermined time or more. If a negative determination is made, this routine is ended as it is, and if a positive determination is made, step 590 is performed.
At this time, the flag F is reset to 0.

Next, the abnormality determination routine of the rear wheel steering device 88 by the steering control device 90 will be described with reference to the flowchart shown in FIG. The determination according to the flowchart shown in FIG. 7 is also executed by interruption every predetermined time.

In step 710 of this routine, a signal indicating the steering angle θf is read, and step 7
At 20, it is judged whether or not the absolute value of the deviation between the target steering angle δrt of the rear wheels and the actual steering angle δr exceeds the reference value δo (a positive constant), that is, the rear wheel steering device 88 is abnormal. It is determined whether or not there is, and when the negative determination is performed, this routine is ended as it is, and when the positive determination is performed, the count value C3 of the counter is incremented by 1 in step 730.

At step 740, the count value C3
Is greater than a reference value (a positive fixed integer), that is, whether the number of times the rear wheel steering device 88 is abnormal is greater than or equal to a predetermined value is determined, and a positive determination is made. Flag is set to 1 in step 750.
Is set to NO and a negative determination is made, step 7
At 60, the flag Ff is reset to zero.

Thus, in the illustrated embodiment, the vehicle side slip acceleration Vyd is calculated in step 20, the vehicle body slip angle β is calculated in step 30, and the linear sum of these is calculated in step 40. The spin amount SV is calculated as, and the spin amount SV is calculated in step 50.
Is calculated as an absolute value of the spin state quantity SS.

Then, in step 60, it is judged whether or not the vehicle is in the non-grip state, and when it is in the non-grip state, in step 70 the spin state quantity SS
Based on the above, the spin control amount Rsspin is calculated from the map corresponding to the graph shown in FIG. 8, and when a negative determination is made, the spin control amount Rsspin is 0 in step 80.
Is set to Further, at step 90, it is judged whether or not the turning behavior of the vehicle is stable based on the spin control amount Rsspin.

When the turning behavior of the vehicle is stable, an affirmative decision is made in step 90 to control each valve in step 100 to the normal position shown in FIG. Therefore, in this case, the behavior control in steps 110 to 160 is not executed, so that the braking force of each wheel is controlled according to the depression amount of the brake pedal 12 by the driver.

When the turning behavior of the vehicle is in the spin state, a negative determination is made in step 90, the final target slip ratio Rsi of each wheel is calculated in steps 110 and 120, and in step 130. The target wheel speed Vwti of each wheel is calculated, and the braking force thereof is controlled in steps 140 to 160 so that the wheel speed of each wheel becomes the target wheel speed Vwti.

Also according to the illustrated embodiment, step 3
At 20 and 340, the steering angle deviation ΔSγ is calculated as the first parameter corresponding to the deviation between the slip angle of the front wheels and the slip angle of the rear wheels based on the steering angle θf and the yaw rate γ, and in steps 360 to 390. Steering angle deviation Δ
The grip state index value Gγ is calculated based on Sγ and the road surface friction coefficient μg, and in steps 430 to 450, it is determined whether or not the vehicle is in the non-grip state based on the grip state index value Gγ. At some time, the flag F1 is set to 1.

Similarly, in steps 330 and 350, the steering angle deviation ΔSgy is calculated as the second parameter corresponding to the deviation between the slip angle of the front wheels and the slip angle of the rear wheels based on the steering angle θf and the lateral acceleration Gy. Step 360
And the steering angle deviation ΔSgy in steps 400 to 420.
And grip condition index value G based on friction coefficient μg of road surface
gy is calculated, and in steps 460 to 480, it is determined whether or not the vehicle is in the non-grip state based on the grip index value Ggy. When the vehicle is in the non-grip state, the flag F2 is set.
Is set to 1.

Then, in step 490, the determination based on the grip state index value Gγ and the grip state index value Ggy
It is determined whether or not the non-grip state is in the non-grip state, and if the determination of these two non-grip states continues for a predetermined time or more, an affirmative determination is made in step 510 and the flag F is set to 1. Set. In other words, when both the steering angle deviation ΔSγ based on the steering angle and the yaw rate and the steering angle deviation ΔSgy based on the steering angle and the lateral acceleration are larger than the deviations corresponding to the friction coefficient of the road surface for a predetermined time or more, the non-grip occurs. It is determined to be in a state.

Therefore, in this case, a positive determination is made in step 60, and in step 70, the spin control amount Rsspin is calculated from the map corresponding to the graph shown in FIG. 8 based on the spin state amount SS, Spin control amount Rss
If pin is not 0, an affirmative decision is made in step 90, whereby the spin suppression control of steps 110 to 160 is carried out.

When the flag F1 or F2 becomes 0 after the flag F is set to 1, that is, when the determination based on the grip state index value Gγ or the determination based on the grip state index value Ggy becomes the grip state, Step 49
A negative determination is made at 0, an affirmative determination is made at step 540, a determination is made as to whether or not the flag F1 is 0 at step 550, and a state in which the flag F1 is 0 is predetermined. If it continues for more than time, step 590
At this time, the flag F is reset to 0.

Therefore, once it is determined that the vehicle is in the non-grip state by both the determinations based on the first and second parameters, the steering angle deviation ΔSγ based on the steering angle and the yaw rate is a deviation corresponding to the friction coefficient of the road surface. If the smaller state continues for a predetermined time or more, the grip state is determined. Further, in this case, a negative determination is made in step 60, and the spin control amount Rsspin is 0 in step 80.
Is set to, a positive determination is made in step 90, whereby the spin suppression control in steps 110 to 160 is prohibited.

In particular, according to the illustrated embodiment, the steering control device 90 determines whether or not the rear wheel steering device 88 is abnormal according to the routine shown in FIG. 7, and the rear wheel steering device is abnormal. At some time, the flag Ff is set to 1. Then, in step 55 of the behavior control routine, it is determined whether or not the flag Ff is 1, that is, the rear wheel steering device 8
8 is abnormal. If the rear wheel steering system is abnormal, the spin control amount Rsspin is set to 0 in step 80, and a positive determination is made in step 90. Since each valve is controlled to the normal position in 100, the spin suppression control in steps 110 to 160 is prohibited, which causes the spin suppression control to be executed in an abnormal situation in the rear wheel steering system. Therefore, it is possible to surely prevent the vehicle from being adversely affected.

For example, FIG. 13 shows changes in the spin control amount Rsspin when the grip state index value Gγ exceeds the reference value Gγ1 after an abnormality has occurred in the rear wheel steering system in the conventional case and the embodiment. It is a time chart.

In FIG. 13, assuming that the rear wheel steering device 88 has an abnormality at time t1, and the grip state index value Gγ exceeds the reference value Gγ1 at time t2, time t.
The flag Ff becomes 1 at 1 and the flag F1 becomes 1 at time t2. In the conventional behavior control device in which the determination corresponding to step 55 is not performed, the spin control amount Rsspin is calculated according to the spin state amount SS after the time t2, and a negative determination is made in step 90. As a result, the spin suppression control is executed by executing steps 110 to 160 in a state where the rear wheel steering system is abnormal, and therefore the behavior of the vehicle is likely to deteriorate rather.

On the other hand, according to the illustrated embodiment, the flag Ff is set to 1 at the time point t1 and the flag F1 is also set to 1 at the time point t2, but the steps are performed after the time point t1. Since the positive determination is made at 55, the spin control amount Rsspin after the time t1
Becomes 0, which surely prevents the spin suppression control in steps 110 to 160 from being executed even after the time t2.

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

For example, in the above-described embodiment, the spin state quantity SS is calculated based on the lateral acceleration and yaw rate of the vehicle, and the steering angle deviation ΔSγ and the steering angle deviation are calculated when the spin state quantity is equal to or larger than the reference value. The spin suppression control is executed when it is determined that the vehicle is in the non-grip state based on both ΔSgy, but the behavior control in the present invention may be executed in any manner. For example, when the behavior of the vehicle is in the drift-out state, drift-out suppression control may be performed in which a turning assist yaw moment is applied to the vehicle and the vehicle is decelerated, and both spin suppression control and drift-out suppression control may be performed. Good.

Further, in the above-described embodiment, the determination as to whether or not the rear wheel steering system is abnormal is executed before step 60, but it is executed after step 60. Also, when the rear wheel steering system is abnormal, the calculation for behavior control is not performed unnecessarily,
It may be executed after step 10.

[0075]

As is apparent from the above description, according to the present invention, the behavior control by the behavior control means is prohibited when the auxiliary steering means becomes abnormal and the steering performance is not normal. It is possible to surely prevent the behavior of the vehicle from worsening by executing the above.

[Brief description of the drawings]

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

FIG. 2 is a flowchart showing a behavior control routine in the embodiment.

FIG. 3 is an estimated value μg of the friction coefficient of the road surface in the embodiment.
3 is a flowchart showing the calculation routine of FIG.

FIG. 4 is a flowchart showing the first half of a vehicle grip state determination routine in the embodiment.

FIG. 5 is a flowchart showing the latter half of a vehicle grip state determination routine in the embodiment.

FIG. 6 is a schematic configuration diagram showing a rear wheel steering device.

FIG. 7 is a flowchart showing an abnormal range routine of the rear wheel steering system according to the embodiment.

FIG. 8 is a graph showing a relationship between a spin state quantity SS and a spin control quantity Rsspin.

FIG. 9: Target slip amount SPi and duty ratio D of each wheel
6 is a graph showing the relationship between ri.

FIG. 10 is a graph showing a relationship between a longitudinal speed Vx and a low speed processing coefficient Ka.

FIG. 11 is a graph showing a relationship between a front-rear speed Vx and a low speed processing coefficient Kb.

FIG. 12 is a graph showing a relationship between a friction coefficient μg of a road surface and a dead zone set value μgm.

FIG. 13 is a time chart showing changes in the spin control amount Rsspin when an abnormality occurs in the rear wheel steering system in the conventional case and the embodiment.

[Explanation of symbols]

 10 ... Braking device 14 ... Master cylinder 16 ... Hydro booster 20, 22, 32, 34 ... Brake hydraulic pressure control device 28, 50FL, 50FR ... Control valve 44 ... Switching valve 48FL, 48FR, 64RL, 64RR ... Wheel cylinder 70 ... Electric type Control device 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 88 ... Rear wheel steering device 90 ... Steering control device

Claims (1)

[Claims] 1. A vehicle behavior control device comprising auxiliary steering means and behavior control means for stabilizing the behavior of the vehicle by controlling the braking force of each wheel based on the estimated behavior of the vehicle, A vehicle behavior control device comprising means for prohibiting the behavior control by the behavior control means when an abnormality occurs in the auxiliary steering means.