JPH0885438A - Antiskid control device - Google Patents

Abstract

PURPOSE: To properly control the wheel slip state according to the vehicle turn state and reconcile the wheel slip state and brake deceleration by providing a vehicle body speed estimating method changing means changing the estimating method of the vehicle body speed by a vehicle body speed estimate section in response to the correction slip ratio calculated by a correction slip ratio calculating means. CONSTITUTION: The wheel speed, longitudinal acceleration, and lateral acceleration are read based on the signals from a wheel speed sensor, a longitudinal G sensor, and a lateral G sensor (S100). The lateral slip correction quantity of front wheels is calculated and set in response to the lateral acceleration at the time of a turn (S101). The absolute value of the calculated slip ratio correction quantity is compared with the predetermined set value (S102). When the slip correction quantity is larger than the set value, Vcar is estimated in consideration of the slip correction quantity (S104). The slip correction quantity is calculated, the lateral slip ratio of the front wheels is changed and set according to the turn state, and the wheel speed is corrected based on the correction quantity of the slip ratio so that the pseudo vehicle body speed does not exceed the actual vehicle body speed (S105).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle antiskid control device.

[0002]

2. Description of the Related Art A vehicle anti-skid control (ABS) system is effective in avoiding wheel lock during braking on a low μ road or the like. For obtaining a pseudo vehicle speed value used for detection, for example, the technique disclosed in Japanese Patent Publication No. 41-17082 is known. Since the highest wheel speed among the wheels is closest to the vehicle speed (vehicle body speed), this select high wheel speed is selected as the pseudo vehicle speed. In this anti-skid control device, such a technique is based on a means for detecting the wheel speed of each wheel, a means for selecting a wheel speed detection value of each wheel speed detecting means, and a pseudo wheel speed based on the selected wheel speed of the wheel speed selecting means. It may be configured by a vehicle body speed estimation system including means for calculating the vehicle speed.

[0003]

The problem shown in FIG. 10 is as follows.
It is a consideration view which illustrates transition of various quantities when following such a method. A wheel speed sensor is arranged on each wheel, for example, four wheels on the front, rear, left, and right, and the wheel speed Vw is calculated according to the output of the wheel speed sensor provided in such a manner. For example, as shown in FIG. The wheel speed Vw is filtered to calculate a value Vwfi (i = 1 to 4) closer to the vehicle speed for each wheel, and the largest value is selected from each Vwfi depending on conditions such as braking / non-braking. Vwf closest to the vehicle speed
The vehicle body speed can be estimated by a method of calculating (the vehicle body speed intermediate value) and further obtaining the pseudo vehicle body speed Vi based on this Vwf. Specifically, the figure is for braking, and Vwf is the select high of Vwf1 of one wheel of the front wheels and Vwf2 of the other wheel. Also, V
“Car” indicates the transition of the actual vehicle body speed during braking.

However, in the conventional system, when the following control is also used in combination, the pseudo vehicle body speed Vi as the following estimated vehicle body speed value is increased (whisker).
(See consideration FIG. 11) This phenomenon is found to occur. That is, in the case where the ABS system-equipped vehicle is further equipped with a control capable of detecting the turning state of the vehicle and setting the slip ratio of each wheel according to the turning state, the pseudo vehicle body speed Vi is higher than the actual vehicle body speed. Therefore, the deceleration may decrease. For example, in yaw rate feedback (F / B) control in which the yaw rate of the vehicle is detected and the slip ratio of each wheel is changed so as to approach the target yaw rate, the vehicle becomes understeer (a tendency toward insufficient turning) during turning braking. In some cases, the slip of the turning outer wheel may be reduced.

On the other hand, when the generated yaw rate is large, as shown in FIG. 12, the difference between the vehicle speed Vcar and the wheel speed of the turning outer wheel, which is originally higher than the vehicle speed, becomes large. In the drawing, the following symbols represent the following.

[0006]

[Table 1] (d / dt) φ; yaw rate tf; distance between front and left and right wheels tr; distance between rear wheels and left and right wheels l; distance between front and rear wheels lf; distance between front wheel and vehicle center of gravity 1r; rear wheel- Distance between the center of gravity of the vehicle Vx; speed in the front-rear direction of the vehicle Vy; speed in the left-right direction of the vehicle Vwfro; wheel speed of the front right wheel = Vcar + (d / dt)
φ · (tf / 2) Vwflo; wheel speed of front left wheel = Vcar− (d / dt)
φ · (tf / 2) Vwrro; wheel speed of rear right wheel = Vcar + (d / dt)
φ · (tr / 2) Vwrlo; wheel speed of rear left wheel = Vcar− (d / dt)
φ ・ (tr / 2)

The figure shows a state during left turn, and the difference between the Vwfro value and the Vwroro value for the right wheel, which is the outer turning wheel, is large with respect to the vehicle body speed Vcar as described above.

In such a case, if the slip of the turning outer wheel is controlled so as to be shallow, the wheel speed of the turning outer wheel will be recovered accordingly, as shown in FIG. 11, and in some cases, it may become higher than the actual vehicle body speed. is there. As a result, the vehicle body speed intermediate value Vwf also increases, and the pseudo vehicle body speed Vi also increases accordingly. As described above, in the conventional vehicle body speed calculation method, the pseudo vehicle body speed Vi increases. Pseudo vehicle speed Vi
Such whirling of the value causes undesired reduction of the braking deceleration during the ABS control.

The present invention, without the above problems,
It is an object of the present invention to provide an anti-skid control device capable of appropriately controlling the wheel slip state in accordance with the turning state of the vehicle during the anti-skid operation and achieving both the deceleration and the braking deceleration.

[0010]

According to the present invention, the following anti-skid control device is provided. That is, the vehicle body speed estimation unit that detects the vehicle wheel speed and estimates the vehicle body speed from the vehicle wheel speed is provided, the slip rate of the vehicle wheel is calculated from the vehicle wheel speed and the vehicle body speed, and the slip rate of the vehicle wheel is maintained at the target slip rate. An anti-skid device that controls the braking hydraulic pressure to prevent wheel locking, a turning state detection unit that detects the turning state of the vehicle, and a slip ratio correction amount according to the turning state detected by the turning state detection unit. Corrected slip ratio calculation means for calculating, target slip ratio calculation means for calculating a target slip ratio using the corrected slip ratio calculated by the corrected slip ratio calculation means, and corrected slip calculated by the corrected slip ratio calculation means Anti-skid control, which comprises a vehicle body speed estimation method changing means for changing the vehicle body speed estimation method in the vehicle body speed estimation section according to the rate. The device (FIG. 1) and a vehicle body speed estimation unit that detects the vehicle wheel speed and estimates the vehicle body speed from the vehicle wheel speed, obtains the wheel slip rate from the vehicle wheel speed and the vehicle body speed, and the wheel slip rate becomes the target slip rate. An anti-skid device that controls the braking fluid pressure so as to keep the wheels from being locked, a turning state detection unit that detects the turning state of the vehicle, and a target turning state calculation unit that calculates a target value of the vehicle turning state. A correction slip ratio calculating means for calculating a slip ratio correction amount according to a deviation between the turning state detected by the turning state detecting means and the target turning state calculated by the target turning state calculating means; Target slip ratio calculating means for calculating the target slip ratio using the corrected slip ratio calculated by the ratio calculating means, and the corrected slip ratio calculated by the corrected slip ratio calculating means In response, an anti-skid control device, characterized in that it comprises a vehicle speed estimating method changing means for changing the method of estimating vehicle speed in the vehicle speed estimation section (FIG. 2).

Further, in the above description, the vehicle body speed estimation method changing means prevents the estimated vehicle body speed value from being less than the actual vehicle body speed when the calculated corrected slip ratio falls within a predetermined range of values. A change means including a switching process to either mode of correcting the wheel speed information applied to the vehicle body speed estimation or applying a strong filter. It is an anti-skid control device. Further, the turning state detecting means is a detecting means including a yaw rate sensor or a vehicle body lateral direction acceleration sensor, which is an anti-skid control device.

[0012]

With the above-described structure, the vehicle body speed estimation unit for detecting the vehicle wheel speed and estimating the vehicle body speed from the vehicle wheel speed is provided, and the wheel slip rate is determined from the vehicle wheel speed and the vehicle body speed. In the case of anti-skid control that controls the braking hydraulic pressure so that it is maintained at a constant level, if a control that detects the turning state of the vehicle and that can set the slip ratio of the controlled wheel variably according to the turning state is incorporated Even in the case where the estimated vehicle body speed value does not become less than the actual vehicle body speed, if the slip rate is corrected by the turning state, the estimated vehicle body speed may be twisted by the correction amount of the slip rate. It is possible to handle the proper wheel speed in consideration thereof.
Therefore, during turning braking, the vehicle behavior control is also performed by appropriately setting the target slip state to match the vehicle turning state and correcting the vehicle behavior while avoiding the whirling state discussed above. It is possible to achieve both anti-skid control and securing braking deceleration at that time even in such a control situation.

Further, according to the present invention, as described in claim 2,
The slip state correction means, the target turn state calculation means, and the slip ratio correction amount are calculated according to the deviation between the turn state detected by the turn state detection means and the target turn state calculated by the target turn state calculation means. And a target slip ratio calculating unit for calculating a target slip ratio from the calculated corrected slip ratio, and a method for estimating a vehicle body speed in a vehicle body speed estimating unit according to the calculated corrected slip ratio. Having each of the vehicle body speed estimation method changing means to be changed makes it possible to realize the above similarly, and in this case, the vehicle behavior is disturbed,
When a deviation between the detected turning state of the vehicle and the target turning state occurs, the control can be performed in consideration of the deviation as well, and more effectively, the maneuverability of the vehicle and the braking deceleration are compatible in the same scene. Make it possible.

Further, when the calculated corrected slip ratio falls within a predetermined range of values, the vehicle body speed estimation method changing means prevents the estimated vehicle body speed value from being more than the actual vehicle body speed. The present invention can be implemented in a configuration including a switching process to either mode in which the correction is applied to the wheel speed information applied to the estimation or in which a strong filter is applied. Make it possible to realize that.

Further, the present invention can be implemented in a structure in which the turning state detecting means includes a yaw rate sensor or a vehicle body lateral direction acceleration sensor, and similarly, it becomes possible to realize the above.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a diagram showing the configuration of an embodiment of the present invention.
In the present embodiment, the vehicle to be applied is a 4-channel ABS that can independently control the left and right brake fluid pressures for both the front and rear wheels.

In the figure, 1 is a brake pedal, 2 is a booster as a brake booster, 3 is a reservoir, 4 is a master cylinder (M / C), and 10F.
L and 20FR indicate the left and right front wheels of the vehicle, and 30RL and 40RR indicate the left and right rear wheels thereof. Each wheel 10FL, 20F
R, 30RL, 40RR are wheel cylinders (W /
C) 11, 21, 31 and 41 are provided, and an actuating actuator for avoiding wheel lock during braking is provided between the master cylinder 4 and these wheel cylinders.

In the illustrated example, the inlet valves 12, 22, 32, 42 and outlet valves 13, 23, 33, 43 are provided in the channels for each wheel, and the reservoirs 8, 9 and the pump 6 driven by the motor 5 are provided. , 7 are included as elements, and an anti-skid device for constructing an ABS circuit by connecting and connecting these as shown in the drawing is provided. Each of the inlet valves 12, 22, 32, 42 and the outlet valves 13, 23, 33, 43 is ON / O.
It is a two-position solenoid valve of FF control, and here, by switching these valves, the brake hydraulic pressure (braking hydraulic pressure P) is individually controlled for the wheel cylinders 11, 21, 31, 41 of the corresponding wheels. The pressure is increased, held (holding pressure), and reduced.

Inlet valves 12, 22, 32, 42
Is in the open position when OFF, and the outlet valves 13, 23, 33, 43 are in the closed position when OFF, and in this state, the hydraulic pressure from the master cylinder 4 is supplied to the corresponding wheel cylinder. At this time, the brake fluid pressure is increased toward the master cylinder fluid pressure, which is the original pressure, and each wheel is individually braked. In this example, when the inlet valve of the corresponding channel is turned on from the above state to switch to the closed position, the pressure holding state is such that the brake fluid pressure of the wheel cylinder of the corresponding channel is not increased or decreased. When the outlet valve is turned on to switch from the closed position to the open position, the brake fluid pressure is released to the corresponding reservoir to reduce the pressure. The brake fluid accumulated in the reservoirs 8, 9 due to the pressure reduction is returned to the upstream of the inlet valves 12, 22, 32, 42 by the pumps 6, 7 driven by the motor 5.

Regarding the ABS actuator,
It may be by a known ordinary or modified anti-skid device other than the configuration exemplified above,
For example, use one ON / OFF control type three-position solenoid valve for each channel that can control pressure reduction, pressure retention, and pressure increase. At the pressure reduction position, the corresponding wheel cylinder hydraulic pressure is reduced and the pressure holding position is maintained. The corresponding hydraulic pressure may be held at the time of, and the corresponding hydraulic pressure may be increased at the increased pressure position.

Each valve 12, 2 of the anti-skid device
2, 32, 42 and 13, 23, 33, 43, and the motor 5 are controlled by an output signal of the controller 50, and the controller 50 controls the front, rear, left and right wheels 10FL,
Signals (Vw) from wheel speed sensors 51, 52, 53, 54 for detecting wheel speeds Vw of 20FR, 30RL, 40RR.
1, Vw2, Vw3, Vw4) are input respectively. Further, in the present embodiment, the controller 50 includes a longitudinal acceleration sensor (a longitudinal G sensor) 61 for detecting a longitudinal acceleration Xg.
From the left / right acceleration sensor (left / right G sensor) 62 for detecting the left / right acceleration Yg (lateral acceleration). Here, these G sensors are used to obtain information for determining the turning state of the vehicle (for the sensors 71 and 72 in the one-dot chain line additionally noted in the drawing,
See below).

The controller 50 includes an input detection circuit, an arithmetic processing circuit, and a storage circuit for storing various control programs executed by the arithmetic processing circuit and arithmetic results.
It includes inlet valves 12, 22, 32, 42, outlet valves 13, 23, 33, 43, and an output circuit for supplying a control signal to the motor 5.

A of 4-channel 4-sensor type as in this example
In the case of the BS control, the controller 50 basically obtains wheel speed information for each channel of the front, rear, left, and right four wheels in order to prevent the brake lock of the wheels, estimates the vehicle body speed from the wheel speeds, and By determining the slip of the corresponding wheel from the vehicle speed and controlling the braking hydraulic pressure so that the slip ratio λ of the wheel is maintained at the target slip ratio, the wheel lock during braking is avoided.

Further, in addition to simply controlling the slip ratio of the wheels within a predetermined target range, the front wheels, etc. are controlled so as to perform appropriate vehicle behavior control in accordance with the vehicle turning state during turning braking. When the target slip ratio of the wheel to be controlled is set according to the detected turning state, the above ABS control is executed, and in addition, the slip ratio is set according to the turning state. In addition, when the slip ratio is corrected by the turning state so that the pseudo vehicle body speed Vi does not become lower than the actual vehicle body speed, the controller 50 can cause the whirling of Vi by the correction amount of the slip ratio. The proper wheel speed should be taken into consideration when handling it. Preferably, when estimating the vehicle speed value in consideration of the slip ratio correction amount, the controller 50 detects the turning state, calculates the slip ratio correction amount according to the detected turning state, and While calculating the target slip ratio from the corrected slip ratio, it also executes control to change the method of estimating the vehicle speed when estimating the vehicle speed according to the calculated corrected slip ratio. Do this by doing.

Further, preferably, the controller 50 changes the vehicle body speed estimation method in accordance with the corrected slip ratio,
For example, from the normal estimation method described in FIG.
This is performed by switching to a method of correcting the vehicle body speed intermediate value Vwf.

FIG. 4 is a flowchart of an example of a control program executed by the controller 50, which also includes a vehicle body speed estimation method changing process. Step S10 described below
The processing from 0 to S105 is executed by a regular interrupt at regular time intervals by an operating system (not shown).
5 and 6 are a characteristic diagram for calculating a slip ratio correction amount applicable to this control example and an explanatory diagram of a vehicle body speed estimation method in consideration of the slip ratio correction amount, and FIG.
It is an example of a BS control table.

In FIG. 4, step S100 is a reading process. In this program example, first, the wheel speed Vwi (i = 1 to 4) is based on the signals from the wheel speed sensor, the front-rear G sensor, and the left-right G sensor. ), Longitudinal acceleration (front-rear g) Xg, and left-right acceleration (left-right g) Yg.

In the following step S101, in this program example, the slip correction amount Δλs is determined according to the turning state of the vehicle.
To calculate. In this embodiment, the slip correction amount Δλs is calculated according to the front-rear g and the left-right g during turning braking as follows.

First, when both the value Xg and the value Yg of g before and after reading and right and left g in step S100 are larger than a predetermined set value, for example, | Xg | ≧ 0.
When 4 g and | Yg | ≧ 0.4 g, it is determined that the turning is sudden braking at a medium μ or more, and in this case, in this case, according to the turning left / right g (Yg) at this time, the front wheel is set here. Left and right 10
The slip correction amounts Δλs of FL and 20FR are set according to the control map as shown in FIG. 5, for example.

In the characteristic shown in the figure, first and second predetermined values Ygo and Yg1 are set for the right and left g (Yg). In this case, the slip correction amount Δλs to be obtained is shown in the figure as an example of the characteristic of the turning outer wheel side (the upper side Δλsout characteristic in the figure) which becomes the outer wheel side of the left and right wheels according to the turning direction. As described above, the right and left g take the value 0 in the range up to the first predetermined value Ygo, and the left and right g further exceed that value and the second predetermined value Y
In the range from the value Ygo to the value Yg1 up to g1, the right and left g increase as shown in the figure as the left and right g increase.
Further, in the range where the right and left g further exceeds the predetermined value Yg1, the characteristic is such that the right and left g increases as shown in the figure with a lower increase rate compared to the degree of increase in the range of the value Ygo to the value Yg1. ing. Therefore, when the right and left g show a value equal to or smaller than the predetermined value Ygo, the value 0 is applied as the slip correction amount Δλs value. Further, here, when the right and left g is the value Yg1, the slip correction amount Δλs is set to a predetermined set value λslim.

Furthermore, here, the example of the characteristics on the turning inner wheel side (the lower Δλsin characteristic in the figure) also conforms to the above-mentioned characteristics as shown in FIG. 5 (FIG. 5).
Is symmetrical with the left and right wheels, but of course, I'm not particular about this).

In the processing of step S101,
Based on the above characteristics, the slip correction amount Δλs for the left and right front wheels is calculated and set according to the left / right g at the time of turning. The slip correction amount Δλs thus obtained is set to the target slip ratio (λs = λso (basic value) + Δλ) as described later.
While being applied to s), it is also applied to the following processing contents.

Here, the left and right front wheels are touched, but the left and right rear wheels 30RL and 20RR may be controlled in the same manner as above. Further, when the rear wheel has one channel, the slip correction amount Δλs may be set so that the slips on both the left and right wheels are deep.

Next, in step S102 and thereafter, the vehicle speed V is determined by the magnitude of the calculated slip ratio correction amount Δλs.
The car estimation method is switched. In this embodiment, in step S102, the calculated slip ratio correction amount Δλs
It is checked whether or not | Δλs | ≧ λslim by comparing the absolute value | Δλs | And
If the slip correction amount Δλs is smaller than the set value λslim, the process proceeds to step S103, and Vcar is set by the normal method.
Is estimated (that is, Vi is calculated). On the contrary, when the slip correction amount Δλs is larger than the set value λslim (when | Δλs | ≧ λslim is satisfied), the process proceeds to step S104, and V considering the slip correction amount Δλs is taken.
Car estimation is performed.

First, regarding the processing in the case of proceeding to step S103, Vi can be calculated by the usual method as described above. In the present embodiment, the wheel speed Vw of each wheel is filtered so that the vehicle speed is closer to Vwfi (i = 1).
4) is calculated for each wheel, Vwf (vehicle body speed intermediate value) closest to the vehicle body speed is calculated by, for example, selecting the largest one from each Vwfi value according to conditions such as braking / non-braking, Further, the pseudo vehicle body speed Vi (estimated value) is obtained based on this value Vwf. As a result of the determination in step S102, when the step S103 side is selected, in this way, step S1
The vehicle body speed is estimated by 03, and thus, the next step S105 for the anti-skid control, that is, the wheel slip is obtained from the wheel speed and the vehicle body speed (estimated value), and the wheel slip ratio falls within the target range. Step S105 for the hydraulic pressure control process for controlling the brake hydraulic pressure so as to be maintained
Proceed to.

On the other hand, when the process proceeds to step S104, Vcar is estimated in consideration of the slip correction amount Δλs. As described above, in the present ABS control, the slip correction amount Δλs is calculated according to the turning state, and the process of changing and setting the slip ratios of the left and right front wheels 10FL, 20FR according to the turning state is also used. Even if such a control is incorporated, the pseudo vehicle body speed Vi is adjusted so that the pseudo vehicle body speed Vi does not become lower than the actual vehicle body speed as shown in FIG. The wheel speed on the wheel side (the wheel speed on the corrected side) that may cause whirling is handled as follows to prevent such whirling.

Specifically, in this embodiment, as shown in FIG. 6, when the slip of the turning outer wheel is controlled to be shallow, the slip rate correction amount Δλs is set value λsli.
When it becomes larger than m, when the Vwf on the side to be corrected is created, the correction is performed so that the Vwf of the wheel does not become too large (see the broken line after the correction in FIG. 7B).

For example, in the case of turning left, when calculating the value Vwfrf on the turning outer wheel side (here, the right wheel is the outer wheel), the Vwf when the correction amount Δλs exceeds the set value λslim is stored. Keep it. In the example of FIG. 6, assuming that the value at that time is the illustrated Vwfrfo value as shown in FIG. 6B, the value Vwfrfo is remembered, and the increase amount of Vwfrf thereafter is a constant ratio α. A correction is added to reduce Vwfrf by the method of discounting with. That is, the corrected Vwfrf of the solid line in FIG. 7B is corrected to the corrected Vwfrfh indicated by the broken line, for example, corrected Vwfrf = Vwfrfh = Vw.
frfo + (Vwfrf−Vwfrfo) × α.

In a situation where the turning state of the vehicle corresponds to the turning state in which the step S104 side is selected in step S102, the slip correction amount Δλs is corrected by such correction.
Step S10 while estimating Vcar considering
Go to step 5. In this way, FIG.
Even in the case of ABS operation at the time of left turning braking such that the pseudo vehicle speed Vi is whispered as shown by the one-dot chain line in (a), it is avoided as shown in FIG. Further, in the case of performing the above correction, more preferably, V
In order to prevent the discontinuity of wf, once the correction is started, the correction is continued until Vwf becomes lower than Vwfo (in the example of FIG. 6, the Vwfrfo value stored at the start of correction). This makes it possible to realize more suitable control.

As described above, the change of the vehicle body speed estimation method is switched according to the corrected slip ratio. In the processing of step S105 after the estimation processing of step S103 or step S105, the calculation is performed as described above. The braking force adjustment for the anti-skid control, which also uses the control capable of setting the wheel slip ratio according to the turning state of the vehicle in accordance with the determined Vi, may be performed as usual.

Here, the wheel acceleration (d / dt) Vw is also used, the wheel acceleration (d / dt) Vw is calculated from the wheel speed for each wheel, and the calculated slip ratio λ and the wheel acceleration ( d / dt) Vw, the wheel lock is determined, and the brake fluid pressure of the corresponding wheel is reduced, held, increased, etc. to prevent wheel slip, and control is performed to keep the target slip λs = λso + Δλs set.

Here, as the second term component on the right side of the above equation, the Δλs value obtained according to FIG. 5 is applied to correct the target value. Therefore, it is not necessary to change the target value,
In the region where the generated right and left g is relatively small, the value 0 is applied to the second term, and as a result, the target value is set for both the left and right wheels at λs = λso, and the target value is requested to be changed according to the turning state. In the area indicated by Fig.
A corresponding value Δλs of is applied to the second term component to set the target value so that the actual slip ratio λ falls within the target range. For example, in the case of 3-mode ABS, if the wheels tend to lock, The braking force is controlled by repeating the skid cycle in which the wheel cylinder hydraulic pressure is held, the pressure is reduced if the wheel cylinder is still locked, and the pressure is increased when the wheel rotation speed is recovered.

In the present embodiment, for example, a control table as shown in FIG. 7 may be used to control the braking fluid pressure, and the calculated slip ratio λ and the wheel acceleration (d / dt) V may be used.
By applying w to the ABS control table, it is assumed that the wheel cylinder pressure is reduced, maintained, or increased for each wheel.
In accordance therewith, control signals to the corresponding inlet valve, outlet valve, etc. are set and output, thereby executing the ABS control for preventing wheel lock during braking.

With the above control, in this embodiment,
In the ABS operation at the time of turning braking, even if the control capable of setting the target slip ratio of each wheel according to the turning state is incorporated, the method as shown in FIGS. 10 and 11 is uniformly applied. In such a case, the problem that the pseudo vehicle body speed Vi is less than the actual vehicle body speed and the deceleration is reduced can be solved. It is possible to change the method for estimating the vehicle body speed in the vehicle body speed estimation calculation according to the slip rate correction amount Δλs.
If the slip ratio is corrected by the turning condition so that the vehicle speed does not become lower than the actual vehicle speed, the wheel speed that may cause the Vi of the Vi is determined by the correction amount Δλs of the slip ratio. In this embodiment, which can be dealt with in consideration of the above, the target slip ratio of each wheel is set according to the turning state during turning braking, and the ABS is set.
The control can be operated, and at the same time, the braking deceleration can be ensured at the same time.

Next, by way of example, the above-described embodiment (first embodiment) is provided with a vehicle body speed estimating section for detecting the wheel speed and estimating the vehicle body speed from the wheel speed. In an anti-skid control device that obtains wheel slip and controls braking fluid pressure so that the wheel slip rate is maintained at a target slip rate to prevent wheel lock, a turning state detection means that detects the turning state of the vehicle A corrected slip ratio calculating means for calculating a slip ratio correction amount according to the turning state detected by the turning state detecting means; a target slip ratio calculating means for calculating a target slip ratio from the corrected slip ratio; This is the case where the vehicle body speed estimation method conversion means for changing the vehicle body speed estimation method in the vehicle body speed estimation section is provided according to the calculated corrected slip ratio. The embodiment further includes a target turning state calculation means for calculating a target value of the turning state, and the correction slip ratio calculation means calculates the turning state detected by the turning state detection means and the target turning state calculation means. The calculation means calculates the correction amount of the slip ratio according to the deviation of the target turning state, and the target slip ratio calculation means calculates the target slip ratio from the calculated correction slip ratio.
The method for estimating the vehicle body speed in the vehicle body speed estimating unit is changed according to the calculated slip ratio thus calculated.

FIG. 8 is an example of a control program executed by the controller 50 in this embodiment (second embodiment). Here, for the system configuration of anti-skid control,
In the case of the present embodiment, in the configuration of FIG.
Instead of the 1 and left and right G sensors 62, a yaw rate sensor 71 that detects a yaw rate (d / dt) φ generated by the vehicle and a steering angle sensor 72 that detects a steering angle δ are used, and signals from these sensors are sent to the controller 50. Shall be entered. Other system configurations may be the same.

Further, in the program example shown in FIG.
4 is different from that of FIG. 4 in the steps S200 to S203, and the other steps S204 to S207 are in accordance with the processing contents in the corresponding steps S102 to S105 of FIG. 4, respectively. .

To explain the main part, first, in step S200, the wheel speeds Vwi (i = 1 to 1) are signals from the wheel speed sensors 51 to 54, the yaw rate sensor 71, and the steering angle sensor 72. 4), yaw rate (d / d
t) Read φ and steering angle δ.

Next, in step S201, the target yaw rate (d / dt) φ ^* is calculated. In the present embodiment, a steady yaw rate (d / dt) φo is set according to the characteristic diagram of the vehicle as shown in FIG. 9, and the set yaw rate (d / dt) φo is delayed according to the following equation. The target yaw rate (d / dt) φ ^* is calculated.

To [number 1] ^{(d / dt) φ * =} (d / dt) φ 0 / (1 + τs) ··· 1 Here, τ the time constant, s is a Laplace operator.

Further, the setting of the target rate (d / dt) φ ^* is not limited to this example, and may be set from the vehicle speed and the steering angle, for example, by the following formula.

## EQU00002 ## (d / dt) .phi. ^* = (. Delta..times.Vx) / (A.times. (1 + K.times.Vi)) ... 2 where A is a constant determined by the wheel base of the vehicle and the steering gear ratio, and , K are constants representing the steering characteristics of the vehicle.

In a succeeding step S202, a deviation Δ (d / dt) φ between the actual yaw rate (d / dt) φ and the target yaw rate (d / dt) φ ^* is calculated according to the following equation.

## EQU3 ## Δ (d / dt) φ = (d / dt) φ ^* − (d / dt) φ ... 3 Next, in step S203, the yaw rate deviation Δ is obtained.
The slip correction amount Δλs is calculated according to (d / dt) φ. In this embodiment, Δλs is calculated according to the following equation.

## EQU4 ## Δλs = k1 × Δ (d / dt) φ ... 4 where k1 is a proportional constant determined by vehicle specifications

In this way, the actual value of yaw rate (d
/ Dt) φ and target value (d / dt) φ ^*Deviation Δ (d /
dt) φ to calculate the slip ratio correction amount Δλs
It This Δλs is the yaw rate deviation of the target slip ratio.
Depending on the, for example, when controlling the front left and right wheels independently,
The target value of the slip ratio is corrected as in the above embodiment.
It is also used, so that maneuverability of the vehicle etc.
The ABS control can be enhanced. For example, wheel load when turning left
Target slip on the heavy outer wheel (front right wheel 20FR)
The understeer tendency is corrected with the correction rate Δλs
If set to correct, the vehicle behavior will be
The turning performance of the vehicle is improved and yaw rate F / B / ABS
Control is realized.

In this case, the control is so-called proportional control only, but the present invention is not limited to this, and it is of course possible to adopt a control mode in which a differential operation or an integral operation is added. Further, here, like the above-described embodiment, only the left and right front wheels are touched, but the same control may be performed for the left and right rear wheels. Further, in the case where the rear wheels are of one channel, the slip correction amount Δλs may be set so that the slips on both the left and right wheels become deeper.

The control contents after step S204 after calculating the slip correction amount Δλs as described above may be the same as those in the above-mentioned embodiment. That is, in the next step S204, the method for estimating the vehicle body speed Vcar is switched depending on the magnitude of the slip correction amount Δλs. Also in the present embodiment, if the slip correction amount Δλs is smaller than the set value λslim, the process proceeds to step S205, Vcar is estimated (that is, Vi is calculated) by a normal method, and conversely, the slip correction amount Δλs is set. If it is larger than the value λslim, the process proceeds to step S206, and Vc in which the slip correction amount Δλs is taken into consideration.
Try to estimate ar.

When the process proceeds to step S205, Vi is calculated by the usual method as described above. Also in this embodiment,
By filtering the wheel speed Vw of each wheel, Vwfi (i = 1 to 4) closer to the vehicle body speed is calculated for each wheel, and the largest one from each Vwfi is selected according to conditions such as braking / non-braking. Vwf (vehicle body speed intermediate value) closest to the vehicle body speed is calculated by, for example, and the pseudo vehicle body speed Vi is obtained based on this Vwf.

On the other hand, if the process proceeds to step S206, Vcar is estimated in consideration of the slip correction amount Δλs. Also in this embodiment, as shown in FIG. 6, when the slip of the turning outer wheel is controlled to be shallow and the slip correction amount Δλs becomes larger than the set value λslim, Vwf on the corrected side is corrected. When creating, the correction is added so that the Vwf of the ring does not become too large. For example, similarly, when calculating the turning outer wheel Vwfrf (the right wheel is the outer wheel), remember the Vwf when the correction amount exceeds the set value (the value in this case is Vwfrf
Vwfrf is reduced by a method of discounting the increase amount of Vwfrf thereafter by a constant ratio α.
That is, the corrected Vwfrf = Vwfrfh = Vwfr
Let fo + (Vwfrf−Vwfrfo) × α. Similarly, in order to prevent the discontinuity of Vwf, once the correction is started, the correction is continued until Vwf falls below Vwfo.

Similarly, in step S207, normal anti-skid control is performed according to Vi calculated as described above. That is, the wheel acceleration is calculated from the wheel speed, the wheel lock is determined based on the slip ratio and the wheel acceleration, and the brake fluid pressure is reduced, held, and increased to prevent the wheel slip, and control is performed to keep the target slip.
Also in this embodiment, the control hydraulic pressure is controlled by the control table shown in FIG.

Although the control according to the control table is used here, the target slip (λs = λso) is applied to the estimated Vi.
The control fluid pressure may be controlled so that the target value Vw ^* multiplied by + Δλs) is obtained (PD control or the like).

Also in this embodiment, the same operational effect as that of the above-mentioned embodiment can be obtained. Even when the yaw rate F / B control is incorporated in the ABS control, the effectiveness of such combination control can be achieved. Vehicle generated yaw rate (d / d
t) φ is controlled so that the wheel slip ratio is changed so as to approach the target yaw rate (d / dt) φ ^*. Under yaw rate F / B control, the turning outer wheel is tried to improve the turning ability when the vehicle becomes understeer during turning braking. Can be controlled individually to make the slip on the side shallower. Then, as shown in the consideration FIG. 12, when the generated yaw rate is large, the difference between the wheel speed of the outer turning wheel and the vehicle speed, which is originally higher than the vehicle speed, becomes large. When the yaw rate F / B control is performed so as to be shallow, the slip of the turning outer wheel at that time becomes shallow, the wheel speed of the turning outer wheel is recovered accordingly, and in some cases, becomes higher than the actual vehicle body speed. As a result, when the vehicle body speed estimation method change control is not adopted, as described above, the vehicle body speed intermediate value Vwf also increases, and the pseudo vehicle body speed Vi also increases accordingly.
According to the present embodiment, even when a situation that causes a decrease in deceleration occurs, even if variable setting control of the target slip ratio λs according to the yaw rate deviation Δ (d / dt) φ is combined and used, the yaw rate ( In a wide control range of d / dt) φ, it is possible to easily realize control that can achieve a high degree of compatibility between vehicle maneuverability and braking deceleration at yaw rate F / B / ABS.

In the present embodiment, in order to change the vehicle body speed estimation method according to the corrected slip ratio, two methods, that is, a normal estimation method and a method for correcting Vwf, are switched. More simply, a strong filter may be applied to wheels having a large corrected slip ratio. Further, this point is the same as in the case of the first embodiment.

[0061]

According to the anti-skid control device of the present invention, even if the vehicle turning state is detected and the control capable of variably setting the slip ratio of the wheel to be controlled according to the turning state is estimated. If the slip ratio is corrected by the turning condition so that the vehicle speed value does not become lower than the actual vehicle speed, the wheel that may cause the estimated vehicle speed to be distorted by the amount of slip ratio correction. It is possible to handle the speed in consideration of that, and it is appropriate to correct the vehicle behavior by adjusting the target slip state to the vehicle turning state while avoiding such a rudder state during turning braking. It is possible to achieve both anti-skid control that also sets the vehicle's behavior to control the vehicle behavior, and to secure the braking deceleration at that time even in such a control situation. Rukoto can, it is possible to further improve the effectiveness of the anti-skid control.

Further, according to the present invention, as described in claim 2,
The slip state correction means, the target turn state calculation means, and the slip ratio correction amount are calculated according to the deviation between the turn state detected by the turn state detection means and the target turn state calculated by the target turn state calculation means. And a target slip ratio calculating unit for calculating a target slip ratio from the calculated corrected slip ratio, and a method for estimating a vehicle body speed in a vehicle body speed estimating unit according to the calculated corrected slip ratio. The above can be similarly realized by including each of the vehicle body speed estimation method changing means to be changed. In this case, when the vehicle behavior is disturbed and a deviation between the detected turning state of the vehicle and the target turning state occurs, The control can be performed in consideration of the deviation, and more effectively, it is possible to realize both the controllability of the vehicle and the braking deceleration in the same scene.

Further, according to the present invention, when the calculated vehicle speed estimation method changing means corresponds to the value of the calculated corrected slip ratio within a predetermined range, the estimated vehicle speed value does not become less than the actual vehicle speed. As described above, it is possible to carry out with a configuration including a switching process to either mode of correcting the wheel speed information applied to the vehicle body speed estimation or applying a strong filter. Can be realized.

Further, the present invention can be implemented in a configuration in which the turning state detecting means includes a yaw rate sensor or a vehicle body lateral direction acceleration sensor, and the above can be similarly realized.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an anti-skid control device of the present invention.

FIG. 2 is likewise a conceptual diagram of an anti-skid control device.

FIG. 3 is a system diagram showing a configuration of an embodiment of the present invention.

FIG. 4 is a flowchart showing an example of a control program executed by the controller of the same example.

FIG. 5 is a characteristic diagram showing an example of characteristics for calculating a slip ratio correction amount that can be applied to the program.

FIG. 6 is a diagram for explaining an example of a vehicle body speed estimation method in consideration of a slip ratio correction amount.

FIG. 7 is a control table showing an example of an anti-skid control pattern.

FIG. 8 is a flowchart showing an example of a control program according to another embodiment of the present invention.

FIG. 9 is a diagram showing an example of characteristics applicable to the program and used for setting a target yaw rate.

FIG. 10 is a diagram for explaining the characteristics, which is shown for understanding the control of the embodiment.

FIG. 11 is a diagram which similarly serves for the same description.

FIG. 12 is a diagram which similarly serves for the same description.

[Explanation of symbols]

 1 Brake Pedal 2 Booster 3 Reservoir 4 Master Cylinder 5 Motor 6,7 Pump 8,9 Reservoir 10FL, 20FR Left and Right Front Wheels 30FL, 40FR Left and Right Rear Wheels 11, 21, 31, 41 Wheel Cylinder 12, 22, 32, 42 Inlet Valve 13, 23, 33, 43 Outlet valve 50 Controller 51-54 Wheel speed sensor 61 Longitudinal acceleration (longitudinal G) sensor 62 Longitudinal acceleration (longitudinal G) sensor 71 Yaw rate sensor 72 Steering angle sensor

Claims (4)

[Claims] 1. A vehicle body speed estimation unit that detects a vehicle wheel speed and estimates a vehicle body speed from the vehicle wheel speed, obtains a wheel slip rate from the vehicle wheel speed and the vehicle body speed, and keeps the wheel slip rate at a target slip rate. Anti-skid device that controls the brake fluid pressure to prevent the wheels from being locked, the turning state detection means that detects the turning state of the vehicle, and the slip ratio that depends on the turning state detected by the turning state detection means. A correction slip ratio calculating unit for calculating a correction amount, a target slip ratio calculating unit for calculating a target slip ratio using the correction slip ratio calculated by the correction slip ratio calculating unit, and a correction slip ratio calculating unit for calculating the target slip ratio. The vehicle body speed estimating method changing means for changing the vehicle body speed estimating method in the vehicle body speed estimating section according to the corrected slip ratio. Kid controller. 2. A vehicle body speed estimation unit that detects a vehicle wheel speed and estimates a vehicle body speed from the vehicle wheel speed, obtains a wheel slip rate from the vehicle wheel speed and the vehicle body speed, and keeps the wheel slip rate at a target slip rate. An anti-skid device that controls the braking fluid pressure to prevent wheel locking, a turning state detection unit that detects the turning state of the vehicle, and a target turning state calculation unit that calculates a target value of the vehicle turning state, Corrected slip ratio calculation means for calculating a slip ratio correction amount in accordance with the deviation between the turning state detected by the turning state detection means and the target turning state calculated by the target turning state calculation means, and the corrected slip ratio calculation Target slip ratio calculation means for calculating the target slip ratio using the corrected slip ratio calculated by the means, and the corrected slip ratio calculated by the corrected slip ratio calculation means. Te, anti-skid control device, characterized in that it comprises a vehicle speed estimating method changing means for changing the method of estimating vehicle speed in the vehicle speed estimation unit. 3. The vehicle body speed estimation method changing means, when the calculated corrected slip ratio falls within a predetermined range of values, the vehicle body speed estimated value does not become less than an actual vehicle body speed, so that It is a changing means including a switching process to either mode of correcting the wheel speed information applied to the speed estimation or applying a strong filter. The anti-skid control device according to claim 1 or claim 2. 4. The turning state detecting means is a detecting means including a yaw rate sensor or a vehicle body lateral direction acceleration sensor, wherein the turning state detecting means includes a yaw rate sensor or a vehicle body lateral direction acceleration sensor.
Antiskid control device as described.