JP2001233193A - Motion control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately perform the over-steering restricting control even in the case where the counter-steering is performed during the over-steering restricting control. SOLUTION: A braking force control means FC determines the safety during the motion of a vehicle including the turning movement of the vehicle on the basis of the output detected by a motion condition detecting means DT, and controls the braking force applied to each wheel WL while controlling a braking force applying means BR in response to a result of the determination. When a counter-steering determining means CS determines that the steering is operated in a direction opposite to the turning direction of the vehicle during the over- steering restricting control, a correcting means CR corrects the control quantity of the over-steering restricting control to each wheel by the braking force control means FC so as to be larger than the control quantity of the over-steering restricting control set on the basis of the geometric relation of each wheel to the turning direction of the vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion control device for a vehicle, and more particularly, to applying a braking force to each wheel during vehicle motion including turning of the vehicle, regardless of whether a brake pedal is operated. The present invention relates to a vehicle motion control device for stabilizing the motion state of a vehicle.

[0002]

2. Description of the Related Art In recent years, attention has been paid to a means for directly controlling a turning moment by controlling a left and right difference of a braking force as a means for controlling a motion characteristic of a vehicle, in particular, a turning characteristic. For example, in Japanese Patent Application Laid-Open No. 9-164932,
When it is determined that the vehicle is excessively oversteering while turning, the braking force is applied to each wheel of the vehicle so as to generate an outward moment with respect to the vehicle, the oversteer suppression control is performed, and the vehicle is excessively steered while turning. A motion control device is disclosed which applies a braking force to each wheel of a vehicle so as to generate an inward moment on the vehicle when it is determined that the vehicle is understeer, and performs understeer suppression control. This publication proposes, in particular, performing correction control so that the braking force applied to each wheel increases or decreases in accordance with the estimated change rate of the road surface friction coefficient. Note that the oversteer suppression control and the understeer suppression control are collectively referred to as braking steering control.

The apparatus disclosed in Japanese Patent Laid-Open Publication No. Hei 8-91197 aims at optimally controlling spin and drift-out according to the running condition of the vehicle, and based on the yaw rate and the amount of sideslip of the vehicle. A behavior control device for a vehicle including a first behavior estimation device and a second behavior estimation device for estimating a turning behavior, and a behavior stabilization device for stabilizing the turning behavior of the vehicle based on the behavior estimated by them is proposed. Have been. The behavior stabilizing device stabilizes the turning behavior of the vehicle based on the spin state when the drift-out state is estimated by the first behavior estimation apparatus and the spin state is estimated by the second behavior estimation apparatus. It is configured.

[0004]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. Hei 9-164 is disclosed.
In the motion control device described in Japanese Patent Application Laid-Open No. 932, no consideration is given to the case where so-called countersteering is performed during oversteer suppression control. Further, Japanese Patent Application Laid-Open No.
Drift-out and spin described in 91197 correspond to excessive understeer and excessive oversteer described in JP-A-9-164932, respectively, but in the device described in JP-A-8-911197, No consideration is given to the case where countersteering is performed during spin suppression control (oversteer suppression control).

[0005] Since countersteering is a steering operation in the direction opposite to the turning direction of the vehicle, if countersteering is performed during oversteer suppression control, the steering is performed based on the geometric relationship of each wheel with respect to the turning direction of the vehicle. The desired effect cannot be expected with the control amount of the normal oversteer suppression control set as above. However, since counter-steering is performed by the driver's intention, this cannot be ignored.

For this reason, it is necessary to ensure the desired effect of the oversteer suppression control while permitting control according to the driver's intention. Further, when the countersteering operation amount is larger than the angle formed by the line connecting the center of gravity of the vehicle to the front wheel with respect to the center axis of the vehicle, there is a possibility that the oversteer may be promoted. It is also necessary. The details of this point will be described later.

Therefore, the present invention provides a vehicle motion control device for controlling a braking force applied to each wheel in accordance with a vehicle motion state, even if countersteering is performed during oversteer suppression control. It is an object of the present invention to be able to perform steering suppression control.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a braking force for applying a braking force to each wheel of a vehicle according to at least an operation of a brake pedal. Providing means, and a motion state detecting means disposed on the vehicle and detecting a signal representing the motion state of the vehicle,
Determining stability during vehicle motion including turning of the vehicle based on a detection output of the motion state detecting means, and controlling the braking force applying means in accordance with the determination result to control a braking force on each of the wheels. A steering control device for determining whether or not a steering operation has been performed in a direction opposite to a turning direction of the vehicle; and an oversteer. When the counter steer determining means determines that the steering operation has been performed in the opposite direction to the turning direction of the vehicle during the restraining control, the control amount of the oversteer suppressing control for each wheel by the braking force control means is changed to the turning of the vehicle. Greater than the control amount of the oversteer suppression control set based on the geometric relationship of each wheel with respect to the direction It is obtained by a further comprising a correcting means for correcting the so that.

According to a second aspect of the present invention, the correction means includes means for controlling a steering angle of the vehicle in a direction opposite to a turning direction of the vehicle by adjusting a countersteering operation amount of a front wheel of the vehicle in a geometrical position of the vehicle. When the angle is larger than the angle indicating the correction, the correction by the correction unit may be prohibited. Note that, as the countersteering operation amount, the absolute value of the steering angle of the front wheels of the vehicle when the steering operation is performed in a direction opposite to the turning direction of the vehicle is used, and the geometrical value of the front wheels of the vehicle in the vehicle is used. As the angle representing the position, it is desirable to use an angle formed by a line connecting a center of gravity of the vehicle with respect to a center axis of the vehicle and a front wheel of the vehicle.

In a preferred embodiment, the vehicle includes a yaw rate detecting means for detecting a yaw rate of the vehicle, and a steering state detecting means for detecting a steering state of the vehicle. It may be configured such that it is determined whether or not a steering operation has been performed in a direction opposite to a turning direction of the vehicle, based on a yaw rate detected by the yaw rate detecting means and a steering state detected by the steering state detecting means.

Further, as set forth in claim 4, target yaw rate setting means for setting a target yaw rate of the vehicle, and a deviation between the target yaw rate set by the target yaw rate setting means and a yaw rate detected by the yaw rate detecting means. The apparatus may further comprise a deviation calculating means for calculating, wherein the correcting means sets a correction amount of the correcting means in accordance with a deviation of a calculation result of the deviation calculating means.

[0012]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an embodiment of a motion control device according to the present invention, wherein braking force applying means BR for applying a braking force to at least each wheel WL of the vehicle in accordance with at least operation of a brake pedal BP; Motion state detection means DT for detecting a signal representing the motion state of the vehicle;
By judging the stability during the vehicle motion including the turning of the vehicle based on the detection output of the motion state detecting means DT, and controlling the braking force applying means BR according to the judgment result to control the braking force on each wheel. At least a braking force control means FC for performing oversteer suppression control is provided.

The counter steer determining means CS for determining whether the steering operation has been performed in the direction opposite to the turning direction of the vehicle, and the counter steer determining means performs the steering in the direction opposite to the turning direction of the vehicle during the oversteer suppression control. If it is determined that the operation has been performed, the braking force control means FC
And a correcting means CR for correcting the control amount of the oversteer suppression control by the control unit to be larger than the control amount of the normal oversteer suppression control set based on the geometric relationship of each wheel with respect to the turning direction of the vehicle. ing. However, when the front wheel on the outer side of the turning of the vehicle is located on the inner side of the turning from the trajectory in the traveling direction of the center of gravity of the vehicle, even if the counter steer determining means CS determines that the steering operation is performed in the opposite direction to the turning direction of the vehicle, the correction is performed. Correction by means CR is prohibited.

The exercise state detecting means DT in the present embodiment
Is a vehicle speed detecting means D1 for detecting the vehicle speed of the vehicle.
And lateral acceleration detecting means D2 for detecting the lateral acceleration of the vehicle
And yaw rate detecting means D for detecting the yaw rate of the vehicle
And the braking force control means FC calculates the vehicle body side slip angular velocity Dβ based on the detected body speed of the vehicle body speed detection means D1, the detected lateral acceleration of the lateral acceleration detection means D2, and the detected yaw rate of the yaw rate detection means D3. In addition, the vehicle body slip angle β is calculated by integrating the vehicle body slip angular velocity Dβ. The steering state detecting means DS includes a steering angle detecting means for detecting a steering angle of the vehicle.

The counter steer determining means CS
Based on the yaw rate detected by the yaw rate detecting means D3 and the steering state detected by the steering state detecting means DS, it is configured to determine whether or not the steering operation has been performed in the direction opposite to the turning direction of the vehicle. Further, target yaw rate setting means (not shown) for setting a target yaw rate of the vehicle, and deviation calculating means (not shown) for calculating a deviation between the target yaw rate set by the target yaw rate setting means and the detected yaw rate of the yaw rate detecting means D3. ), And the correction amount of the correction means CR is set according to the deviation. The details will be described later with reference to FIGS.

FIG. 2 shows the overall structure of a vehicle including the motion control device. An engine EG is an internal combustion engine provided with a throttle control device TH and a fuel injection device FI. In the throttle control device TH, an accelerator pedal AP is used. The main throttle opening of the main throttle valve MT is controlled in accordance with the operation of. Further, the sub-throttle valve ST of the throttle control device TH is driven to control the sub-throttle opening in accordance with the output of the electronic control unit ECU, and the fuel injection device FI is driven to control the fuel injection amount. It is configured. The engine EG of the present embodiment is connected to wheels FL,
Although it is connected to the FR, a so-called front wheel drive system is configured, but the drive system in the present invention is not limited to this.

As for the braking system, the wheels FL, FR, R
Wheel cylinders Wfl, Wfr, Wr for L and RR, respectively
1, Wrr are mounted, and a brake fluid pressure control device BC is connected to these wheel cylinders Wfl and the like. The wheel FL indicates the front left wheel when viewed from the driver's seat, the wheel FR indicates the front right wheel, the wheel RL indicates the rear left wheel, and the wheel RR indicates the rear right wheel. In the present embodiment, a so-called X pipe is configured. However, it may be a front and rear pipe.

The wheels FL, FR, RL, RR are provided with wheel speed sensors WS1 to WS4, which are connected to the electronic control unit ECU, and which control the rotational speed of each wheel, that is, the number of pulses proportional to the wheel speed. Is input to the electronic control unit ECU. Further, a brake switch BS that is turned on when the brake pedal BP is depressed, a stroke sensor BR that detects a stroke of the brake pedal BP, wheels FL and F in front of the vehicle.
The front wheel steering angle sensor SSf for detecting the steering angle θf of R, the lateral acceleration sensor YG for detecting the lateral acceleration of the vehicle, and the changing speed of the vehicle rotation angle (yaw angle) around the vertical axis passing through the center of gravity of the vehicle, that is, the yaw angular speed (yaw rate) Is connected to the electronic control unit ECU.

The electronic control unit ECU of the present embodiment has a configuration shown in FIG.
As shown in FIG. 1, a microcomputer CMP comprising a processing unit CPU, a memory ROM, a RAM, an input port IPT, an output port OPT, and the like, which are interconnected via a bus, is provided. The wheel speed sensor WS
1 to WS4, brake switch BS, stroke sensor BR, front wheel steering angle sensor SSf, yaw rate sensor Y
S, the output signal of the lateral acceleration sensor YG, etc. is amplified by the amplifier circuit AMP.
Via the input port IPT to the processing unit CPU. Further, control signals are output from the output port OPT to the throttle control device TH and the brake fluid pressure control device BC via the drive circuit ACT.

In the microcomputer CMP,
The memory ROM stores programs for various processes including the flowcharts shown in FIGS. 3 to 6, the processing unit CPU executes the programs while an ignition switch (not shown) is closed, and the memory RAM stores the programs. Temporarily stores the variable data required for the execution of For each control such as throttle control,
Alternatively, a plurality of microcomputers may be configured by appropriately combining related controls, and the microcomputers may be electrically connected to each other.

In the present embodiment configured as described above, a series of processes such as braking steering control and anti-skid control are performed by the electronic control unit ECU, and when an ignition switch (not shown) is closed. The execution of the program corresponding to the flowcharts of FIG. 3 to FIG. 6 starts. FIG. 3 shows the entire control operation of the vehicle. First, in step 101, the microcomputer CMP is initialized and various calculated values are cleared. Next, step 102
, The detection signals of the wheel speed sensors WS1 to WS4 are read, the detection signal of the front wheel steering angle sensor SSf (steering angle θf), the detected yaw rate γa of the yaw rate sensor YS, and the detected acceleration of the lateral acceleration sensor YG (ie, Acceleration, which is represented by Gya).

Next, the routine proceeds to step 103, where the wheel speed Vw ** of each wheel (** represents each wheel FR etc.) is calculated, and these are differentiated to obtain the wheel acceleration DVw ** of each wheel. Can be Subsequently, in step 104, the maximum value of the wheel speed Vw ** of each wheel is calculated as the estimated vehicle speed Vso at the position of the center of gravity of the vehicle (Vso = MAX (Vw **)). Further, an estimated vehicle speed Vso ** is obtained for each wheel based on the wheel speed Vw ** of each wheel, and if necessary, normalization is performed to reduce an error based on a difference between the inner and outer wheels when the vehicle turns. . Further, the estimated vehicle speed Vso is differentiated, and an estimated vehicle acceleration (including an estimated vehicle deceleration having the opposite sign) DVso at the position of the vehicle center of gravity is calculated.

Next, in step 105, the wheel speed V of each wheel obtained in steps 102 and 103 is calculated.
Based on w ** and the estimated vehicle speed Vso ** (or the normalized estimated vehicle speed), the actual slip ratio Sa ** of each wheel is Sa ** =
(Vso **-Vw **) / Vso **. next,
In step 106, based on the estimated vehicle body acceleration DVso at the position of the center of gravity of the vehicle and the actual lateral acceleration Gya of the detection signal of the lateral acceleration sensor YG, the road surface friction coefficient μ is approximately (DVso ² +
Gya ² ) calculated as ^1/2 . Further, as means for detecting the road surface friction coefficient, various means such as a sensor for directly detecting the road surface friction coefficient can be used.

Subsequently, in steps 107 and 108, the vehicle body slip angular velocity Dβ is calculated, and the vehicle body slip angle β is calculated. The vehicle body slip angle β represents the slip of the vehicle body with respect to the traveling direction of the vehicle as an angle, and can be calculated and estimated as follows. That is, the vehicle body slip angular velocity Dβ is a differential value dβ / dt of the vehicle body slip angle β.
In step 107, Dβ = Gya / Vso−γa can be obtained, and this is integrated in step 108 to obtain the vehicle body side slip angle β as β = ∫ (Gya / Vso−γa) dt.

Then, the routine proceeds to step 109, where a braking steering control mode is set, and a target slip ratio to be used for braking steering control is set, as will be described later. The braking force on each wheel is controlled. This braking steering control is superimposed on control in all control modes described later.
Thereafter, the process proceeds to step 110, where it is determined whether or not the anti-skid control start condition is satisfied. If the start condition is satisfied and it is determined that the anti-skid control is to be started at the time of braking steering, the initial specifying control is immediately terminated and step 111 is performed. Is set to a control mode for performing both braking steering control and anti-skid control.

When it is determined in step 110 that the anti-skid control start condition is not satisfied, the process proceeds to step 112, in which it is determined whether the front-rear braking force distribution control start condition is satisfied. When it is determined that the braking force distribution control is started, the routine proceeds to step 113, where a control mode for performing both the braking steering control and the longitudinal braking force distribution control is set. Is satisfied or not. If it is determined that the traction control is started during the brake steering control, the control mode is set to perform both the brake steering control and the traction control in step 115, and if neither control is determined to be started during the brake steering control, In step 116, it is determined whether the brake steering control start condition is satisfied.

If it is determined in step 116 that the braking steering control has been started, the routine proceeds to step 117, where a control mode in which only the braking steering control is performed is set. Then, after performing the hydraulic servo control in step 118 based on these control modes, the process returns to step 102. In the front / rear braking force distribution control mode, the distribution of the braking force applied to the rear wheels to the braking force applied to the front wheels is controlled so as to maintain stability of the vehicle during braking of the vehicle. Step 116
If it is determined that the conditions for starting the braking steering control are not satisfied in step, the solenoids of all the solenoid valves are turned off in step 119, and the process returns to step. It should be noted that, based on steps 111, 113, 115, and 117, the sub-throttle opening of the throttle control device TH is adjusted as necessary according to the vehicle motion state, the output of the engine EG is reduced, and the driving force is limited. .

FIG. 4 shows the specific processing contents of the brake steering control in step 109 in FIG. 3. The brake steering control includes oversteer suppression control and understeer suppression control. And / or a target slip ratio corresponding to the understeer suppression control is set. First, in steps 201 and 202, the start and end of the oversteer suppression control and the understeer suppression control are determined. The start / end determination of the oversteer suppression control performed in step 201 is based on the vehicle body slip angle β and the vehicle body slip angular velocity Dβ at the time of the determination.
The oversteer suppression control is started when the vehicle enters the control region indicated by hatching in FIG. 9, and the oversteer suppression control is terminated when the vehicle leaves these regions. Control is performed as indicated by the curve. still,
The braking force of each wheel is controlled so that the control amount increases from the boundary lines L1 and L2 toward the outside.

On the other hand, the start / end determination of the understeer suppression control performed in step 202 is made based on whether or not the vehicle is in a control area indicated by oblique lines in FIG. That is, at the time of determination, according to the change of the actual lateral acceleration Gya with respect to the target lateral acceleration Gyt, understeer suppression control is started when the vehicle deviates from the ideal state indicated by the one-dot chain line and enters the control region. Is ended, and control is performed as indicated by the arrow curve in FIG.

Subsequently, it is determined in step 203 whether or not the oversteer suppression control is being controlled, and if not, it is determined in step 204 whether or not the understeer suppression control is being controlled. If not, step 2
09, which will be described later. Step 20
When it is determined in step 4 that the vehicle is understeer suppression control, the routine proceeds to step 205, where the target slip ratio of each wheel is set for understeer suppression control described later. Step 2
If it is determined in step 03 that the vehicle is in the oversteer suppression control, the process proceeds to step 206, where it is determined whether the understeer suppression control is performed.
At 7, the target slip ratio of each wheel is set for oversteer suppression control described later. Step 206
If it is determined that the understeer suppression control is being performed, the oversteer suppression control and the understeer suppression control are performed simultaneously, and the target slip ratio for simultaneous control is set at step 208.

The target slip ratio of each wheel in step 205 is as follows: the front wheel on the outside of the turn is set to Stufo, the front wheel on the inside of the turn is set to Stufi, and the rear wheel on the inside of the turn is Sturi.
Is set to As for the sign of the slip ratio (S) shown here, "t" represents "target" and represents "actual measurement" described later.
Compared to "a". "u" is "understeer suppression control"
"R" represents "rear wheel", "o" represents "outside", "
i "represents" inside ", respectively.

The target slip ratio of each wheel in step 207 is set to Stefo for the front wheel on the outside of the turn and to Steri for the rear wheel on the inside of the turn. Here, “e” represents “oversteer suppression control”. And step 208
The target slip ratios of the respective wheels are set such that the front wheel on the outside of the turn is set to Stefo, the front wheel on the inside of the turn is set at Stufi, and the rear wheel on the inside of the turn is set at Sturi. That is,
When the oversteer suppression control and the understeer suppression control are performed simultaneously, the front wheels on the outside of the turn are set in the same manner as the target slip rate of the oversteer suppression control, and the wheels on the inside of the turn are all set in the same manner as the target slip rate of the understeer suppression control. Is set. In any case, the rear wheels on the outside of the turn (ie, the driven wheels in the front-wheel drive vehicle) are not controlled because the estimated vehicle speed is set.

The vehicle slip angle β and the vehicle slip angular velocity Dβ are used for setting the target slip ratio for the oversteer suppression control in step 207. However, the target lateral acceleration Gyt is used for setting the target slip ratio for the understeer suppression control. And the actual lateral acceleration Gya.
For example, the target slip ratio Stefo of the front wheel on the outside of the turn used for the oversteer suppression control is Stefo = K1 · β + K2.
The target slip ratio Steri of the rear wheel on the inside of the turn is set to “0”. Here, K1 and K2 are constants, which are set to values for controlling the pressing direction (direction for increasing the braking force).

On the other hand, the target slip ratio for the understeer suppression control is set as follows based on the deviation ΔGy between the target lateral acceleration Gyt and the actual lateral acceleration Gya. That is,
The target slip ratio Stufo for the front wheel outside the turning is K3
ΔGy is set, and the constant K3 is set to a value for controlling the pressurizing direction (or the depressurizing direction). The target slip ratio Sturi for the rear wheel on the inside of the turn is set to K4 · ΔGy, and the constant K4 is set to a value for controlling the pressing direction. Similarly, the target slip ratio Stufi for the front wheel inside the turn is set to K5ＫΔGy, and the constant K5 is set to a value for controlling the pressing direction. If it is determined in step 204 that the understeer suppression control is not being performed, and if it is determined that neither the oversteer suppression control nor the understeer suppression control is being performed, the process returns to step 209 through the main routine.

The target slip ratio S for oversteer suppression control set in steps 207 and 208 described above.
tefo is appropriately corrected in step 209. That is, when a steering wheel (not shown) is operated during the oversteer suppression control and countersteering is performed, the target slip ratio Stefo is corrected according to a flowchart of FIG. 5 as described later.

In the above-described embodiment, the control is performed by the slip ratio. However, the control target corresponds to the braking force applied to each wheel such as the brake fluid pressure of the wheel cylinder of each wheel in addition to the slip ratio. Any value may be used as long as it is a target value.

FIG. 5 shows the contents of the oversteer suppression control target slip ratio correction calculation performed in step 209 of FIG. 4. First, in step 301, the turning direction of the vehicle is changed based on the detected yaw rate γa of the yaw rate sensor YS. Is determined. For example, the yaw rate sensor YS
If the detected yaw rate γa is positive, it is determined to be a left turn,
The process further proceeds to step 302, where it is determined whether the output of the front wheel steering angle sensor SSf is positive or negative. In step 302,
When the steering angle θf detected by the front wheel steering angle sensor SSf is determined to be negative, since the turning direction and the steering direction are different,
It is determined that the steering is counter steer. When it is determined in step 302 that the steering angle θf is 0 or positive, the process proceeds to step 306 because the counter steer is not performed, the correction coefficient is set to 1, and the target slip ratio Stefo is not corrected.

If the yaw rate γa is determined to be positive in step 301 and the steering angle θf is determined to be negative in step 302 to determine that the counter steer operation is being performed, the process proceeds to step 303, and the turning direction of the vehicle is determined. It is determined whether or not the countersteering operation amount when the steering operation is performed in the reverse direction is larger than the angle indicating the geometric position of the front wheels in the vehicle. For example, as shown in FIG. 8, the absolute value of the steering angle θf detected by the front wheel steering angle sensor SSf corresponds to the former countersteering operation amount, and is formed by a line connecting the center of gravity of the vehicle VH and the front wheel FR and the vehicle center axis. The angle θk corresponds to the latter angle representing the geometric position. Note that the angle θk
Is tan θk = (Tf / 2) as is clear from FIG.
/ Lf. Here, Tf represents the tread length of the vehicle, and Lf represents the axial distance from the center of gravity of the vehicle to the front wheels.

When it is determined in step 303 that the absolute value of the steering angle θf representing the countersteering operation amount is larger than the angle θk representing the geometric position of the front wheels on the vehicle, as shown in FIG. , And proceeds to step 306, where the correction coefficient is set to 1. On the other hand, when it is determined in step 303 that the absolute value of the steering angle θf is equal to or smaller than the angle θk, the process proceeds to step 308.

On the other hand, if the yaw rate γa is negative in step 301, it is determined that the vehicle is turning right, and the process proceeds to step 304. In step 304, the front wheel steering angle sensor SS
When the detected steering angle θf of f is determined to be positive, it is determined that the counter steer operation is being performed. In this case, the process further proceeds to step 305, and the absolute value of the steering angle θf is compared with the angle θk as in step 303.
Proceeding to 7, the correction coefficient is set to 1. When it is determined in step 304 that the steering angle θf is 0 or negative, the operation proceeds to step 307 because the counter steer is not performed, the correction coefficient is set to 1, and the target slip ratio Stefo is not corrected. When it is determined in step 305 that the absolute value of the steering angle θf is equal to or smaller than the angle θk, the process proceeds to step 308.

Thus, the yaw rate γa is positive (turn left).
When the steering angle θf is negative and the absolute value | θf | of the steering angle θf is equal to or smaller than the angle θk, the process proceeds to step 308, and the correction coefficient Kc is set. When the yaw rate γa is negative (turn right), the steering angle θf is positive, and the absolute value | θf | of the steering angle θf is equal to or smaller than the angle θk, the process proceeds to step 308, and the correction coefficient Kc is set. . The correction coefficient Kc is a deviation Δγ (= γ) between the target yaw rate γt and the detected yaw rate γa.
Based on t-γa), as shown in FIG.
Set to a value less than 5. Then, in step 309, the target slip ratio Stefo is updated by multiplying the target slip ratio Stefo by the correction coefficient Kc (Stefo = Kc).
-Stefo). That is, the target slip ratio Stefo is corrected so as to increase, and the control amount increases.

FIG. 6 shows the processing of the hydraulic servo control performed in step 118 of FIG. 3. In each wheel, the slip ratio servo control of the wheel cylinder hydraulic pressure is performed. First, steps 205, 207 or 20 described above are performed.
The target slip ratio St ** set in step 8 is used in step 40.
1, and these are read as they are as the target slip rates St ** of the respective wheels.

Subsequently, in step 402, the slip ratio deviation ΔSt ** is calculated for each wheel, and in step 403, the vehicle body acceleration deviation ΔDVso ** is calculated.
In step 402, the target slip ratio S of each wheel
The difference between t ** and the actual slip ratio Sa ** is calculated to determine the slip ratio deviation ΔSt ** (ΔSt ** = St ** − Sa *
*). In step 403, the difference between the estimated vehicle acceleration DVso at the position of the center of gravity of the vehicle and the wheel acceleration DVw ** of the wheel to be controlled is calculated, and the vehicle body acceleration deviation ΔDV is calculated.
so ** is required. The actual slip ratio S of each wheel at this time
The calculation of a ** and the vehicle body acceleration deviation ΔDVso ** differ depending on the control mode such as anti-skid control, traction control, etc., but the description thereof will be omitted.

Further, the routine proceeds to step 404, where one parameter Y ** used for brake fluid pressure control in each control mode is calculated as Gs ** · ΔSt **. Where Gs *
* Is a gain and is set as shown by a solid line in FIG. 11 according to the vehicle body slip angle β. In step 405, another parameter X ** to be provided for the brake fluid pressure control is set.
Is calculated as Gd ** · ΔDVso **. The gain Gd ** at this time is a constant value as shown by a broken line in FIG. Thereafter, the routine proceeds to step 406, where the hydraulic mode is set for each wheel according to the control map shown in FIG. 12 based on the parameters X ** and Y **. In FIG. 12, respective regions of a rapid pressure reduction region, a pulse pressure reduction region, a holding region, a pulse pressure increase region and a rapid pressure increase region are set in advance, and in step 406, according to the values of the parameters X ** and Y **. ,
It is determined which area corresponds. In the non-control state, the hydraulic mode is not set (solenoid off).

If the area determined this time in step 406 switches from pressure increase to pressure reduction or pressure reduction to pressure increase with respect to the area determined last time, the fall or rise of the brake fluid pressure is made smooth. Since it is necessary, pressure increase / decrease compensation processing is performed in step 407. For example, when switching from the rapid pressure reduction mode to the pulse pressure increase mode, rapid pressure increase control is performed, and the time is determined based on the duration of the immediately preceding rapid pressure reduction mode. Then, step 40
At step 8, a driving process of a booster switching solenoid (this will be described later) is performed. At step 409, each solenoid valve P constituting the modulator is set in accordance with the hydraulic mode.
A solenoid of C * (representing PC1 to PC8, which will be described later) is driven to control the braking torque for each wheel. Then, at step 410, a motor drive process is performed.

In the braking system including the brake fluid pressure control device BC shown in FIG. 2, the master cylinder MC is boosted via the vacuum booster VB in response to the operation of the brake pedal BP, as shown in FIG. The brake fluid in the LRS is pressurized, and the wheels FR, RL and the wheels FL, R
The configuration is such that the master cylinder hydraulic pressure is output to the two brake hydraulic systems on the R side. Master cylinder MC
Is a tandem-type master cylinder having two pressure chambers. One pressure chamber is connected to the brake fluid pressure system on the wheels FR and RL, and the other pressure chamber is connected to the brake fluid pressure system on the wheels FL and RR. Communication is established. The output side of the master cylinder MC is provided with a pressure sensor PS for detecting the output hydraulic pressure (master cylinder hydraulic pressure).

The vacuum booster VB of this embodiment is
The configuration is the same as that of the conventional vacuum booster, and a constant pressure chamber B2 and a variable pressure chamber B3 are formed via a movable wall B1, and the movable wall B1 is connected to a brake pedal BP. The movable wall B1 includes a vacuum valve (not shown) for interrupting communication between the constant pressure chamber B2 and the variable pressure chamber B3, and an air valve (not shown) for interrupting communication between the variable pressure chamber B3 and the atmosphere. A valve mechanism B4 is provided. And
The constant pressure chamber B2 is configured to always communicate with an intake manifold (not shown) of the engine EG and to introduce a negative pressure. On the other hand, the variable pressure chamber B3 is operated by the valve mechanism B4.
A state in which it is isolated from the constant pressure chamber B2 and communicates with the atmosphere;
It is configured to select a state in which a negative pressure is introduced in communication with the second pressure. Thus, the vacuum valve and the air valve of the valve mechanism B4 open and close in response to the operation of the brake pedal BP, and a differential pressure corresponding to the operation force of the brake pedal BP is generated between the constant pressure chamber B2 and the variable pressure chamber B3. As a result, the output amplified according to the operation force of the brake pedal BP is transmitted to the master cylinder MC.

In the vacuum booster VB of this embodiment, an auxiliary movable wall B5 is further disposed in the constant pressure chamber B2, and an auxiliary variable pressure chamber B6 is formed between the auxiliary movable wall B1 and the movable wall B1. The auxiliary movable wall B5 can move in the direction of the master cylinder MC along with the movement of the brake pedal BP, but is configured to move in the direction of the master cylinder MC independently of the brake pedal BP and drive it. That is, depending on the operation of the booster switching solenoid SB, a state in which the auxiliary transformer chamber B6 communicates with the atmosphere and a state in which the auxiliary transformer B6 communicates with an intake manifold (not shown) of the engine EG and a negative pressure is introduced are selected. It is configured as follows.

The booster switching solenoid SB is constituted by a linear solenoid valve.
13 and the first position connected to the intake manifold of the engine EG and the auxiliary transformer chamber B6 are connected to the atmosphere (FIG. 13).
(Indicated by AR in FIG. 2) is switched by duty control. Thus, if a negative pressure is introduced into the auxiliary transformation chamber B6 via the booster switching solenoid SB, the auxiliary movable wall B5 is maintained at a fixed distance with respect to the movable wall B1, and the master cylinder MC is moved with the movement of the brake pedal BP. However, when the auxiliary variable pressure chamber B6 communicates with the atmosphere, a differential pressure is generated between the auxiliary variable pressure chamber B6 and the negative pressure constant pressure chamber B2. As a result, irrespective of the operation of the brake pedal BP (provisional command,
Even when the brake pedal BP is not operated), the master cylinder MC is driven according to the movement of the auxiliary movable wall B5.

In the brake hydraulic system on the wheels FR, RL side of the present embodiment, one pressure chamber is connected to the wheel cylinders Wfr, Wrl via the main hydraulic path MF and the branch hydraulic paths MFr, MFl, respectively. Have been. Branch hydraulic path M
Fr and MFl respectively include normally open two-port two-position solenoid valves PC1 and PC2 (hereinafter simply referred to as solenoid valves PC1 and PC2).
2). Further, a discharge-side branch hydraulic pressure path R connected to and connected to the wheel cylinders Wfr and Wrl.
A normally closed type two-port two-position solenoid on-off valve PC5, PC6 (hereinafter, simply referred to as solenoid valve PC5, PC6) is interposed in each of Fr and RFl, and the drainage fluid in which branch hydraulic pressure lines RFr and RFl merge. The pressure line RF is connected to the reservoir RS1.

Further, check valves CV1 and CV2 are provided in parallel with the solenoid valves PC1 and PC2, respectively. Check valve CV
1, CV2 permits the flow of brake fluid in the direction of the master cylinder MC and restricts the flow of brake fluid in the direction of the wheel cylinders Wfr, Wrl. The wheel cylinder Wfr is controlled via these check valves CV1, CV2. , Wr
1 is configured to return the brake fluid in the master cylinder MC and eventually to the low-pressure reservoir LRS. Thus, when the brake pedal BP is released, the hydraulic pressure in the wheel cylinders Wfr, Wrl becomes equal to the master cylinder MC
Can quickly follow the hydraulic pressure drop on the side.

In the brake hydraulic system for the wheels FR and RL, a modulator is constituted by the solenoid valves PC1, PC2, PC5 and PC6. Also, the solenoid valve P
A hydraulic pump HP1 is interposed in a hydraulic passage MFp connected to the branch hydraulic passages MFr and MF1 on the upstream side of C1 and PC2, and a reservoir RS is provided on a suction side thereof through a check valve CV5.
1 is connected. The hydraulic pump HP1 is driven by one electric motor M together with the hydraulic pump HP2, and is configured to introduce brake fluid from the suction side, increase the pressure to a predetermined pressure, and output the pressure from the discharge side. Reservoir RS1
Is provided independently of the low-pressure reservoir LRS of the master cylinder MC, and can also be referred to as an accumulator, is provided with a piston and a spring, and is configured to store a volume of brake fluid necessary for various controls described later. Have been.

The discharge side of the hydraulic pump HP1 is provided with a check valve CV
6 and the solenoid valves PC1, PC2 via the damper DP1, respectively.
It is connected to the. The check valve CV5 prevents the flow of the brake fluid to the reservoir RS1, and allows the flow in the reverse direction. The check valve CV6 regulates the flow of the brake fluid discharged through the hydraulic pump HP1 in a certain direction, and is usually integrally formed in the hydraulic pump HP1. Further, a damper DP is provided on the discharge side of the hydraulic pump HP1.
1 is disposed, and a proportioning valve PV1 is interposed in a hydraulic path leading to the wheel cylinder Wrl on the rear wheel side.

Similarly, in the brake hydraulic system on the wheels FL and RR side, a normally open 2-port 2-position solenoid valve PC3, PC4 including a reservoir RS2, a damper DP2 and a proportioning valve PV2, and a normally-closed type. 2-port 2-position solenoid on-off valve PC7, PC8, check valve CV3, CV
4, CV7 and CV8 are provided. The solenoid valves PC1 to PC8 are driven and controlled by the above-described electronic control unit ECU, and various controls including braking steering control are performed.

First, during normal braking operation,
Each solenoid valve is in the normal position shown in FIG.
Has stopped. When the brake pedal BP is depressed in this state, the master cylinder MC is boosted by the vacuum booster VB, and the master cylinder hydraulic pressure is supplied from the two pressure chambers of the master cylinder MC to the wheels FR and R, respectively.
It is output to the brake fluid pressure system on the L side and the wheels FL and RR, and is supplied to the wheel cylinders Wfr, Wrl, Wfl, Wrr via solenoid valves PC1 to PC8. Since the brake hydraulic systems on the wheels FR and RL and the wheels FL and RR have the same configuration, the wheels FR and R will be representatively described below.
The L-side brake hydraulic system will be described.

For example, the mode shifts to the anti-skid control during the braking operation, and when it is determined that the wheel FR side has a tendency to lock, for example, the normally open solenoid valve PC1 is set to the closed position, and the normally closed solenoid valve PC5 is set. Is set to the open position. Thus,
The wheel cylinder Wfr communicates with the reservoir RS1 via the solenoid valve PC5, and the brake fluid in the wheel cylinder Wfr flows out of the reservoir RS1 and is depressurized.

When the wheel cylinder Wfr enters the pulse pressure increasing mode, the solenoid valve PC5 is closed and the solenoid valve PC1 is opened, and the master cylinder MC receives the master cylinder fluid pressure via the solenoid valve PC1 in the open position. To the wheel cylinder Wfr. And the solenoid valve PC1
Is intermittently controlled, and the brake fluid in the wheel cylinder Wfr is repeatedly increased in pressure and held, increases in a pulsed manner, and is gradually increased. When the rapid pressure increase mode is set for the wheel cylinder Wfr, the solenoid valves PC2 and PC5 are set to the closed position, then the solenoid valve PC1 is set to the open position, and the master cylinder MC supplies the master cylinder hydraulic pressure.
Then, when the brake pedal BP is released and the master cylinder hydraulic pressure becomes lower than the hydraulic pressure of the wheel cylinder Wfr, the brake fluid in the wheel cylinder Wfr is sent to the master cylinder MC via the check valve CV1, and eventually to the low-pressure reservoir LRS. Return. In this way, independent braking torque control is performed for each wheel.

On the other hand, when the operation shifts to the traction control, for example, when the acceleration slip prevention control of the wheel FR is performed, the solenoid valves PC2 to PC4 are closed while the solenoid valve PC1 is kept open. In this state, when the hydraulic pump HP1 is driven by the electric motor M, the electromagnetic valve PC1
, The pressurized brake fluid is immediately supplied to the wheel cylinder Wfr on the drive wheel side. If the solenoid valve PC1 is in the closed position, the hydraulic pressure of the wheel cylinder Wfr is maintained. Further, when the booster switching solenoid SB is switched and the auxiliary transformer chamber B6 communicates with the atmosphere, the auxiliary movable wall B5 moves independently of the operation of the brake pedal BP,
The master piston of master cylinder MC is driven forward.

Even when the brake pedal BP is not operated, the hydraulic pump HP1 is driven during the acceleration slip prevention control of the wheel FR, for example, and the solenoid valves PC1 and PC1 are driven according to the acceleration slip state of the wheel FR. By the intermittent control of the PC 5, any one of the hydraulic modes of pulse pressure increase, pulse pressure decrease, and holding is set for the wheel cylinder Wfr.
As a result, the braking torque is applied to the wheels FR, the rotational driving force is limited, acceleration slip is prevented, and traction control can be appropriately performed.

Further, at the time of braking / steering control of the vehicle,
The electric motor M is driven, the brake fluid is discharged from the hydraulic pump HP1, and the electromagnetic valves PC1, PC2, PC5, PC
6 is appropriately controlled to open and close, and wheel cylinders Wfr, Wr
1 is increased, reduced or maintained in pulse, and the wheels FL,
The same control is performed in the brake hydraulic system on the RR side. Thus, the braking force distribution between the front and rear wheels is controlled so that the course traceability of the vehicle can be maintained. For example, when excessive oversteer is prevented in the above-described oversteer suppression control, a braking force is applied to the front wheels on the outside of the turn.

[0061]

The present invention has the following effects because it is configured as described above. That is, in the vehicle motion control device according to the first aspect, when it is determined that the steering operation is performed in the opposite direction to the turning direction of the vehicle during the oversteer suppression control, the oversteer suppression control for each wheel by the braking force control unit is performed. Is controlled so as to be larger than the control amount of the oversteer suppression control set based on the geometric relationship of each wheel with respect to the turning direction of the vehicle. Even when counter-steering is performed, oversteer suppression control is appropriately performed, and a stable vehicle motion state can be maintained.

Further, in the apparatus according to the second aspect,
When the countersteering operation amount is larger than the angle representing the geometrical position of the front wheels in the vehicle, the correction by the correction means is configured to be prohibited, so that oversteering is appropriately suppressed without promoting oversteering. Control can be performed.

If the counter steer determining means is configured as described in claim 3, it is possible to easily determine whether or not the steering operation has been performed in the direction opposite to the turning direction of the vehicle.

Further, if the correction means is constituted as described in claim 4, the correction amount can be set easily and appropriately.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a motion control device according to an embodiment of the present invention.

FIG. 2 is an overall configuration diagram of an embodiment of a motion control device of the present invention.

FIG. 3 is a flowchart showing an entire vehicle braking control according to the embodiment of the present invention.

FIG. 4 is a flowchart illustrating a process of setting a target slip ratio used for braking steering control according to the embodiment of the present invention.

FIG. 5 is a flowchart showing a process of an oversteer suppression control target slip ratio correction calculation in one embodiment of the present invention.

FIG. 6 is a flowchart illustrating a hydraulic servo control process according to an embodiment of the present invention.

FIG. 7 is a graph showing an oversteer suppression control target slip ratio correction coefficient according to an embodiment of the present invention.

FIG. 8 is a plan view showing an example of a wheel state at the time of counter steering according to the embodiment of the present invention.

FIG. 9 is a graph showing a control region of oversteer suppression control in one embodiment of the present invention.

FIG. 10 is a graph showing a control region of understeer suppression control in one embodiment of the present invention.

FIG. 11 is a graph showing a gain for calculating a parameter used for hydraulic pressure control in one embodiment of the present invention.

FIG. 12 is a graph showing a control map according to an embodiment of the present invention.

FIG. 13 is a configuration diagram showing a hydraulic system of the vehicle motion control device of the present invention.

[Explanation of symbols]

BP brake pedal, MC master cylinder, M
Electric motor, HP1, HP2 hydraulic pump, RS
1, RS2 reservoir, Wfr, Wfl, Wrr, Wrl Wheel cylinder, ECU electronic control unit, WS1-WS
4 Wheel speed sensor, PC1 to PC8 Solenoid valve, F
R, FL, RR, RL wheels, EG engine

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D045 BB40 CC01 EE21 FF42 GG00 GG25 GG26 GG27 GG28 3D046 BB21 BB28 BB29 CC02 DD04 GG02 HH02 HH08 HH21 HH23 HH25 HH26 HH36 HH39 HH46 LL10 LL23

Claims (4)

[Claims] 1. A braking force applying means for applying a braking force to at least each wheel of a vehicle in response to an operation of a brake pedal, and a motion state detecting device disposed on the vehicle and detecting a signal representing the motion state of the vehicle. Means for determining stability during vehicle movement including turning of the vehicle based on the detection output of the movement state detecting means, and controlling the braking force applying means in accordance with the determination result to obtain a braking force for each wheel. A vehicle steering control device having at least a braking force control unit that performs at least oversteer suppression control by controlling a countersteer determination unit that determines whether a steering operation is performed in a direction opposite to a turning direction of the vehicle. If the counter steer determining means determines that the steering operation has been performed in the opposite direction to the turning direction of the vehicle during the oversteer suppression control, The control amount of the oversteer suppression control for each wheel by the power control unit is corrected to be larger than the control amount of the oversteer suppression control set based on the geometric relationship of each wheel with respect to the turning direction of the vehicle. A motion control device for a vehicle, comprising: a correcting unit that performs the correction. 2. The correction means according to claim 1, wherein an amount of counter-steering when the steering operation is performed in a direction opposite to a turning direction of the vehicle is larger than an angle representing a geometric position of the front wheels of the vehicle in the vehicle. 2. The vehicle motion control device according to claim 1, wherein the correction of the correction means is sometimes prohibited. 3. A yaw rate detecting means for detecting a yaw rate of the vehicle, and a steering state detecting means for detecting a steering state of the vehicle, wherein the counter steer determining means includes a yaw rate detected by the yaw rate detecting means and the steering state. 2. The vehicle motion control device according to claim 1, wherein it is configured to determine whether a steering operation is performed in a direction opposite to a turning direction of the vehicle based on a detected steering state of the detection unit. 4. A target yaw rate setting means for setting a target yaw rate of the vehicle, and a deviation calculating means for calculating a deviation between a target yaw rate set by the target yaw rate setting means and a detected yaw rate of the yaw rate detecting means.
3. The vehicle motion control device according to claim 2, wherein said correction means is configured to set a correction amount of said correction means in accordance with a deviation of a calculation result of said deviation calculation means.