JP3298286B2 - Anti-skid brake control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method of an anti-skid brake for preventing wheels from locking during braking.

[0002]

2. Description of the Related Art For example, Japanese Patent Laying-Open No. 64-106762 discloses a control method of an anti-skid brake for detecting a rough road such as unevenness and controlling a brake pressure on wheels according to the degree of the rough road. I have. More specifically, in a known control method, first, a rough road index calculation circuit outputs a rough road index, while a control variable calculation circuit outputs control variables of the left and right wheels. Supplied. This filter, when bad road index is small, but outputs the control variable of a wheel in a waveform close to its original shape, contrast, when the bad road index is large, rapid control variables of the wheels in accordance with the rough road exponent It has become outputs a waveform obtained by removing the fluctuation component. If the brake pressure of the wheel is controlled through the operation of the actuator based on the control variable smoothed by the filter as described above, it becomes possible to prevent vibration, pitching, and reduction in acceleration / deceleration of the vehicle body.

[0003]

It is recognized that the above-described known control method can effectively control the brake pressure of the wheels on a rough road having a large degree of unevenness. It is not effective for disturbances that do not catch detection. That is, in FIG.
Change trend of the wheel speed when the brake pressure control by the anti-skid braking system (ABS) is started are the shown in FIG. 1, dashed line shows the case of a high μ road has large friction coefficient, such as an asphalt road surface , On the other hand, the solid line shows the case of low μ road has small coefficient of friction that the road surface is covered with fresh snow. FIG. 1 also shows the vibration state of the wheel acceleration on a low μ road. In FIG. 1, VREF represents the reference vehicle speed.

As apparent from FIG. 1, the brake pressure control by the ABS is performed based on the wheel slip rate and the wheel acceleration. On a high μ road, the control is performed when the wheel slip rate is small. In contrast, low μ
In this case, the control is performed in a region where the wheel slip ratio is large. This is because, as shown in the road surface μ-slip ratio characteristic in FIG. 2, the road surface μ becomes maximum where the slip ratio is small on a high μ road, whereas the slip surface is low on a low μ road. This is because the road surface μ is maximized at a relatively high rate.

[0005] For this reason, after the start of the ABS control, there is no problem if the road surface is a high μ road, but if the road surface is a low μ road such as a fresh snow road, the wheel speed is restored in the process of returning the wheel speed. Even if the wheel speed vibrates at a low speed, the wheel acceleration exceeds the control threshold, and the brake pressure of the wheel is undesirably reduced via the actuator, so that sufficient braking force may not be obtained. In FIG. 1, such a reduction in the brake pressure is indicated by adding a circle to the vibration characteristics of the wheel speed and the wheel acceleration.

[0006] The above-mentioned vibration of the wheel speed is of such a small level as not to be caught by the detection of a bad road. To remove such vibration by a simple filtering process, a filter having a large time constant is required. Due to the response delay of the filter, normal ABS control cannot be optimally performed. The present invention has been made based on the above-described circumstances, and an object thereof is to appropriately extract a disturbance caused by a minute vibration of a wheel speed that is not caught by a bad road detection, and An object of the present invention is to provide a method of controlling an anti-skid brake that prevents undesired pressure reduction of a brake pressure due to a disturbance.

[0007]

SUMMARY OF THE INVENTION The above object is achieved by a method of controlling an anti-skid brake according to the present invention. The method includes a disturbance extracting step of extracting components excluding the components, and a correcting step of correcting brake pressure control by actuation of the actuator based on the vibration component extracted from the disturbance extracting step.

In this case, it is preferable that the predetermined period of the disturbance extracting step is a period corresponding to one cycle of the vibration of the wheel acceleration. Furthermore, the disturbance extraction process of the vibration components of the wheel acceleration, but to extract the excluded component also predetermined value or more ingredients preferred.

In this case, the disturbance extraction step includes the step of calculating the wheel acceleration.
When the vibration component is equal to or more than a predetermined value, the extracted vibration component is
It can be output as 0 .

[0010]

According to the anti-skid brake control method described above, in the disturbance extracting step, of the vibration components of the wheel acceleration indicating the wheel slip information, the components during a predetermined period from the start of the reduction of the brake pressure, specifically, one period of oscillation of the wheel acceleration, more preferably Ru is extracted ingredients excluded a predetermined value or more components. Then, in the correction step, the brake pressure control by the operation of the actuator is corrected based on the extracted vibration component, that is, the vibration component obtained by removing the disturbance component from the original vibration component of the wheel acceleration. More specifically, the brake pressure control is corrected by correcting the slip information of the wheel based on the vibration component of the wheel acceleration from which the disturbance component has been removed.

As a result, especially on a low μ road such as a new snow road.
However, the small vibration component of the wheel acceleration caused by the disturbance
Extraction is possible, and the wheel brake pressure is not
It is possible to prevent the pressure from being reduced as desired.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 3, there is shown schematically an anti-skid brake system (ABS) for a vehicle in which front wheels FL, FR and rear wheels R of an FF vehicle are shown.
Each of the L and RR wheel brakes 2 has a master cylinder 4
Are hydraulically connected via an on / off type actuator, that is, a hydraulic unit (HU) 6 .
Master cylinder 4 with blanking Suta is actuated by depression of the brake pedal 8, it is possible to supply the master cylinder pressure in each wheel brake 2.

Each of the wheels FL, FR, RL, and RR is provided with a pickup coil type wheel speed sensor 10, and a steering wheel 12 and a vehicle body are provided with a photo interrupter type handle angle sensor 14 and a longitudinal acceleration. Sensors (front and rear G sensors) 16 are provided. These sensors 10, 14, 16 are electrically connected to an electronic control unit (ECU) 18, and the ECU 18 can receive detection signals from these sensors.

FIG. 4 shows a part of the HU 6, that is, a brake circuit between one wheel brake 2 and the master cylinder 4. The brake circuit includes a solenoid valve 20 at a three-port three position as an actuator, and the solenoid valve 20 is interposed between the wheel brake 2 and the master cylinder 4.

The solenoid valve 20 is normally switched to a pressure increasing position shown in the figure. At this switching position, the master cylinder 4 and the wheel brake 2 are in a connected state. Therefore, at this time, the brake pedal 8 is depressed
Then , the brake pressure is supplied from the master cylinder 4 to the wheel brake 2. On the other hand, although the configuration is not shown in FIG. 4, when the ABS operates, the hydraulic path between the master cylinder 4 and the solenoid valve 20 is cut off, and the solenoid valve 20 is connected to the hydraulic pump 22. In this case, the hydraulic pump 22 pressurizes the pressurized liquid in the reservoir 24 to a predetermined pressure, and
To the wheel brake 2 through

The brake pressure supplied from the hydraulic pump 22 to the wheel brake 2 is maintained by switching the solenoid valve 20 from the pressure increasing position to the holding position, and the brake pressure is reduced from the holding position. When switched to the position, the pressure is reduced. Due to this pressure reduction, the pressure fluid released from the wheel brake 2 is returned to the reservoir 24.

A check valve 26 for bypassing the solenoid valve 20 is provided between the master cylinder 4 and the wheel brake 2, and the check valve 26 is directed from the wheel brake 2 to the master cylinder 4 side. Allows only pressurized fluid flow. As is clear from the above description, A
If the switching control of the solenoid valve 20, that is, the brake pressure of the wheel is appropriately controlled with the operation of the BS, the locking of the wheel can be prevented.

The switching control of the solenoid valve 20, that is, the ABS main routine, is executed by the ECU 1 based on the slip information based on the wheel acceleration and its slip rate.
8 is performed. The 5 to 7, a functional block diagram of the E CU 18 for running the ABS main routine is shown, first, Figure 5 shows a signal processing section from the sensors described above.

A detection signal taken into the ECU 18 from each wheel speed sensor 10 is converted from a periodic signal into a speed signal by an input processing circuit 28 and then converted to a low-pass filter 30.
Is output as the wheel speed FVX. Further, the wheel speed FVX output from the low-pass filter 30 passes through a differentiating circuit 32 and a low-pass filter 34 to output a wheel acceleration FG.
Output as x. Further, the wheel acceleration FGX from the low-pass filter 34 is output as a wheel jerk JX via a differentiating circuit 36.

The detection signal taken into the ECU 18 from the front / rear G sensor 16 undergoes A / D conversion processing in an input processing circuit 38, and then is subjected to a comparison operation circuit 40 and a low-pass filter
2 and is output as the vehicle body deceleration FGS. When the detection signal from the input processing circuit 38 has a negative value, the comparison operation circuit 40 supplies the absolute value to the low-pass filter 42. Further, the vehicle deceleration FGS from the low-pass filter 42 is calculated by the comparison operation circuit 44 and the low-pass filter 46.
Is output as the vehicle body deceleration FFGS. Here, the comparison operation circuit 44 fixes the value of the vehicle body deceleration FGS to a constant value (for example, a deceleration of 0.6 g) before the operation of the ABS, and supplies the value to the low-pass filter 46.

The detection signal taken into the ECU 18 from the steering wheel angle sensor 14 is converted into an angle signal by an input processing circuit 48 in terms of the number of pulses, and the steering wheel angle θ
Output as H. In FIG. 5, the suffix “X” of the wheel speed FV, the wheel acceleration FG, and the wheel jerk J, and the suffix “X” attached to the following reference symbols are the symbols FL, F of the respective wheels.
R, RL, and RR are shown as representatives.

The aforementioned wheel speed FVX and vehicle body deceleration FGS
(FFGS), the wheel acceleration FGX, the wheel jerk JX, and the steering wheel angle θH are supplied to the microprocessor of the ECU 18. In this microprocessor, FIG.
In the calculation block 50, the wheel speed FVX and the vehicle body deceleration F
Based on the GS (FFGS) and the steering wheel angle θH, the reference vehicle speed VREF is calculated.

Normally, the reference vehicle speed VREF is calculated based on a selected one of the wheel speeds FVX and the vehicle deceleration. However, at the time of a sharp turn where the absolute value of the steering wheel angle θH is large, the arithmetic block 50
The reference vehicle speed V on the outer wheel side is obtained from the wheel speed of the outer wheel and the vehicle deceleration.
At the same time as calculating REFO, a reference vehicle speed VREFI on the inner wheel side is calculated from the wheel speed of the inner wheel and the vehicle body deceleration. AB
Immediately after the operation of S, the front and rear G sensor 16 does not function stably. In this case, the reference vehicle speed VREF is calculated based on the vehicle body deceleration FFGS.

The reference vehicle speed VREF (VREFO, VREFI) and the wheel speed FVX calculated by the calculation block 50 are supplied to the next calculation block 52.
, The slip ratio SX of each wheel is calculated based on the following equation. SX = (VREF−FVX) / VREF × 100 Here, among the wheel speeds FVX supplied to the calculation block 52, the wheel speeds FVRL and FVRR on the rear wheel side are selected according to the principle of the select row shown in FIG. The wheel speed on the low speed side is supplied to the calculation block 52 as the wheel speed FVR.

The correction value of the slip amount and the correction value of the slip ratio calculated in the calculation blocks 54 and 56 are supplied to the calculation block 52. Based on these correction values, the calculation is performed by the above equation. The slip ratio SX is corrected.
Here, the slip amount correction includes a case where the friction coefficient of the road surface is large, that is, a correction on a high μ road, an initial operation correction of an ABS operation, and a vehicle body swing-back correction. Includes vehicle speed correction, rear wheel correction and turning correction.

The slip ratio SX calculated in the operation block 52 is further corrected based on the correction value of the rough road correction calculated in the operation block 58 to become a slip ratio SRX. It is supplied to the operation block 60. The above-described correction of the slip ratio SX prevents the operation of the ABS due to the overhang of the wheel projection, secures braking force on rough roads, improves running stability, and further enhances steering stability when making a sharp turn. Help to improve.

Slip ratio SRX from operation block 52
Is also supplied to an integrating block 62, which calculates an integrated value ISRX of the slip ratio SRX,
The integrated value ISRX is supplied to the operation block 60. Although the wheel acceleration FGX and the wheel jerk JX are also supplied to the calculation block 60, the wheel accelerations FGRL and FGRR and the wheel jerks JRL and JRL and JRL and JRL of the rear wheels are also provided here.
As shown in FIG. 8, the selected wheel acceleration FGR and wheel jerk JR on the low speed side are supplied to the calculation block 60 according to the principle of select low as shown in FIG. Further, as shown in FIG. 8, with respect to the rear wheel-side wheel accelerations FGRL and FGRR, the high-speed side wheel acceleration FGF_SH is also selected in accordance with the principle of select high.
When the value of F_SH becomes larger than 1 g, FIG.
The middle switch 64 is switched to the lower side, and the wheel acceleration FG
It is supplied to the arithmetic block 62 as R.

Further, as shown in FIG. 6, the wheel acceleration FGX supplied to the calculation block 62 is added with a correction value by the above-described rough road correction and lock correction.
The correction value by the disturbance correction is added by the adding unit 100.
Here, the correction value of the rough road correction is added to the wheel acceleration FGX on condition that the ABS is not in operation.
The lock correction means that when the wheel is locked, when the three conditions of FVX <2 km / h, VREF> 5 km / h and 0>FGX> -1g are simultaneously satisfied, the wheel acceleration FG
1g is subtracted from X.

[0029] The correction value of the disturbance compensation is adapted to that calculated from the functional block diagram of FIG. 9, below,
The procedure for calculating the correction value will be described with reference to FIG. First, the wheel acceleration FGX is supplied to a high-pass filter 102 (for example, fc = 6 Hz, τ = 26 msec).
Component is removed ing and HFGX.

The absolute value of the wheel acceleration HFGX is thereafter calculated in a calculation block 104, and the wheel acceleration | HFGX | is supplied from the calculation block 104 to a calculation block 106 (a) . This operation block 106
In (a) , after the ABS is operated and the brake pressure of the target wheel is reduced, the value of one cycle of the vibration component of the wheel acceleration | HFGX | is set to 0 . this
After that, the wheel acceleration | HFGX |
Is supplied (b), the computation block 106 (b) is the wheel acceleration | HFGX | is greater than or equal to 1g case, sets and outputs the value to 0.

Here, one cycle of the wheel acceleration | HFGX | after the reduction of the brake pressure is an ABS vibration component of the wheel acceleration caused by the operation of the ABS itself, and the wheel acceleration | HFGX | In such a case, it is estimated to be a rough road vibration component of the wheel acceleration caused by the rough road.
Therefore, in the operation block 106, the wheel acceleration | HFG
When the ABS vibration component and the rough road vibration component are excluded from the vibration component of X |, the operation block 106 extracts and outputs a disturbance vibration component HCFGX included in the wheel acceleration | HFGX |.

Here, after the ABS is operated, the wheel acceleration HFGX passing through the high-pass filter 102, the wheel acceleration | HFGX | passing through the operation block 104, and the disturbance vibration component HCFGX passing through the operation block 106 are respectively shown in FIG. Is shown in In FIG. 10, a region indicated by S indicates that the ABS vibration component is excluded from the disturbance vibration component HCFGX.

Thereafter, the disturbance vibration component HCFGX is supplied to the low-pass filter 108 (for example, fc = 0.31 Hz, τ = 5
00 msec), and the low-pass filter 108
Is a disturbance vibration component HCFG as shown in FIG.
The vibration level of X, that is, the effective value MAG_FGX of the disturbance is output. Note that the low-pass filter 108 keeps the value immediately before it for one cycle after the brake pressure is reduced by the ABS operation.

Next, the effective value MAG_FGX of the disturbance from the low-pass filter 108 is supplied to the above-mentioned adding section 100, and the adding section 100 calculates the wheel acceleration F
GX is corrected. FGX = FGX + MAG_FGX On the other hand, the effective value MAG_FGX of the disturbance is also supplied to the above-described calculation block 52 as shown in FIGS. 6 and 9, and is used for correcting the slip ratio SX.

That is, the calculation block 52 is provided with a calculation unit 110 for calculating a correction value HSNWX of the slip ratio SX, and the calculation unit 110 calculates the effective value MAG of the disturbance.
The correction value HSNWX of the slip ratio SX is calculated based on the following function using _FGX as a variable. HSNWX = F (MAG_FGX) Specifically, the correction value HSNWX of the slip ratio SX is calculated as shown in FIG.
From the map as shown in the figure, the effective value of disturbance MAG_FGX
Is calculated based on As is clear from this map, the correction value HSNWX of the slip ratio SX is the effective value MA of the disturbance.
G_FGX increases, for example, in the range from 0.2 g or more to 0.5 g as the effective value increases, and takes a constant value when the value is 0.5 g or more.

When the correction value HSNWX of the slip ratio SRX is calculated in this manner, the calculation block 52 corrects the slip ratio SRX based on the following equation. S R X = SX-HSNWX calculation block 60 described above, the slip ratio SRX, the integral value of the slip ratio SRX ISRX, when receiving the wheel acceleration FGX and wheel jerk JX, based on these, it calculates the wheel slip index IIX.

Here, the wheel slip index IIX represents wheel slip information , and the slip ratio SRX and the wheel acceleration FGX are calculated based on the target slip ratio (from the relationship with the road surface friction coefficient μ, the friction coefficient μ The value increases in the positive or negative direction as the value deviates from the target acceleration or a value near the maximum value). Specifically, as the slip ratio SRX increases from the target slip ratio, the wheel slip index IIX
Increases in the negative direction.

On the other hand, the wheel acceleration FGX indicates the recovery trend of the wheel speed. When the wheel acceleration FGX deviates from the target acceleration in a large direction, the wheel slip index IIX
Increases in the positive direction and vice versa. In calculating the wheel slip index IIX in the calculation block 60, the wheel jerk JX and the integrated value ISRX of the slip ratio SRX are considered for the following reason.

Regarding the wheel acceleration FGX, a delay may occur in the output due to the phase delay of the filter system. To prevent this, the recovery tendency of the wheel speed FVX is reduced by considering the wheel jerk JX. , And the wheel slip index IIX can be accurately calculated. On the other hand, since the integrated value IRX of the slip ratio SRX can be used for detecting an extremely low μ road, it is possible to accurately calculate the wheel slip index IIX by detecting the transition from a low μ road to a high μ road early. Becomes

In a calculation block 60, the wheel slip index I
In calculating IX, the calculation block 60 can calculate the wheel slip index IIX by fuzzy inference using the slip ratio SRX, the integrated value ISRX, the wheel acceleration FGX and the wheel jerk JX as input variables.
Wheel slip index II calculated in operation block 60
X is then supplied to an operation block 66 shown in FIG. In this operation block 66, the wheel slip index II
Based on X, a target pressure increase / decrease IDPX to be supplied to the wheel brake 2 of the wheel is calculated. Here, the target pressure increase / decrease IDPX is calculated by adding the above-described correction processing for optimizing the switching operation of the solenoid valve 20 of the HU 6 to the basic pressure increase / decrease determined from the wheel slip index IIX.

The target pressure increase / decrease IDPx calculated in the calculation block 66 is then supplied to a calculation block 68, where the pressure increase / decrease pulse width PW corresponding to the target pressure increase / decrease IDPX is calculated. , Its valve signal V
SX is output. Here, the increasing / decreasing pulse width PWX is H
The pressure increase / decrease pulse width PWX is calculated based on the pressure increase / decrease gain indicating the characteristic of the U6 itself.
Is corrected in consideration of the variation of the pressure increase / decrease gain.

On the other hand, the valve signal VSX is equal to the target pressure increase / decrease I
If DPX is greater than 0, the solenoid valve 20
Becomes a pressure increasing signal for switching the solenoid valve 20 to the pressure decreasing position when the target pressure increasing / decreasing IDPX is smaller than 0. Furthermore,
When the target pressure increase / decrease IDPX is 0, the valve signal VSX is a holding signal for switching the solenoid valve 20 to the holding position.

The increasing / decreasing pulse width PWX calculated in the calculating block 68 is supplied to the solenoid valve 2 through the switch circuits 70 and 72 together with the valve signal VSX. The switch circuit 70 is switched by receiving a determination signal from a determination circuit 74 for determining the start / end of the operation of the ABS. Further, the switch circuit 72 is switched in response to a determination signal from a determination circuit 76 for determining immediately before the operation of the ABS is started.

More specifically, when the determination circuit 76 detects a situation immediately before the start of the operation of the ABS, it temporarily switches the switch to the holding side, and by this switching, holds the solenoid valve 2 corresponding to the wheel. Switch to position. Thereafter, when it is determined by the determination circuit 74 that the ABS should be started, the determination circuits 74 and 76 switch the switch circuits 70 and 72 to the illustrated switching positions, whereby the switch circuits 70 and 72 are switched. 72 supplies the pressure increasing / decreasing pulse width PWX to the solenoid valve 2.

The solenoid valve 2 has an increasing / decreasing pulse width PW
The switching position is switched to one of the pressure increasing position, the pressure reducing position, and the holding position in accordance with X and the valve signal VSX, and the maintenance time at the pressure increasing position or the pressure reducing position is determined. Is controlled to prevent the wheels from locking and locking tendency.

The condition that the switch of the switch circuit 70 is switched to the master cylinder pressure increasing side by the determination circuit 74 means that the master cylinder pressure of the master cylinder 4 is supplied to the wheel brake 2 of the wheel through the solenoid valve 2. A normal state is enabled, in which case the switches of switch circuit 72 are maintained in the illustrated switching positions. The determination in the determination circuits 74 and 76 is performed based on the difference between the reference vehicle speed VREF and the wheel speed FVX.

The main routine of the brake pressure control of the wheel cylinder 2 based on the target pressure increase / decrease IDPX described above, that is, the ABS control by the ECU 18 is shown in FIG. 11, and the main routine includes steps S1 to S7. Execute sequentially. In the main routine, the above-described disturbance correction of the wheel acceleration FGX is performed in step S1, and the disturbance correction of the slip ratio SX is performed in step S3.

As described above, when the wheel slip index IIX is calculated in the calculation block 60, since the wheel acceleration FGX and the slip ratio SX are subjected to disturbance correction, the road surface is a low μ road such as a fresh snow road. Thus, even if the wheel acceleration FGX slightly vibrates, it is possible to prevent the brake pressure from decreasing due to the vibration. More specifically, since the effective value MAG_FGX of the disturbance is added to the wheel acceleration FGX received by the calculation block 60, even if a slight vibration caused by the disturbance occurs in the wheel acceleration FGX after the operation of the ABS, The negative component of the vibration will be canceled by the effective value MAG_FGX of the disturbance.

Therefore, in such a situation, the wheel acceleration FGX does not exceed the control threshold .
That is, in the operation blocks 60 and 66, the wheel slip index IIX for reducing the brake pressure of the wheel and the target pressure increase / decrease IDPX are not output. As a result, it is possible to prevent the brake pressure from being undesirably reduced during the operation of the ABS, particularly on a low μ road such as a fresh snow road, and to secure a stable braking force.

The effective value MAG_FGX of the disturbance is also used for correcting the slip ratio SX, and works in a direction to reduce the slip ratio SX.
It is possible to prevent the brake pressure of the wheel from being undesirably reduced. FIG. 12 shows that when the ABS is operating, the vibration state of the wheel acceleration FGX when the correction process based on the effective value MAG_FGX of the disturbance is not performed is the vehicle deceleration FGS,
FIG. 13 shows changes in the wheel speed FVX and the brake pressure PBX, and FIG. 13 shows the effective value MAG_F of the disturbance.
An example in the case where the correction processing by GX is performed is shown.

In the case of FIG. 12 without correction, during the operation of the ABS, the brake pressure PBX is also caused by the vibration component caused by the disturbance as indicated by the dashed line circle in the vibration component of the wheel acceleration FGX. In the case of FIG. 13 with correction, on the other hand, the vibration of the wheel acceleration FGX in the region surrounded by the dashed line circle is also suppressed, and as a result, the reduction of the brake pressure is avoided. You can see that it is.

In extracting the effective value MAG_FGX of the disturbance, ABS is extracted from the vibration component of the wheel acceleration FGX.
Since the ABS vibration component due to the operation itself and the rough road vibration component due to the rough road are excluded, it is possible to use the high-pass filter 102 or the low-pass filter 108 which is simple and has a small time constant. In addition to accurately extracting a minute vibration component caused by the above, it is possible to prevent a response delay.

The present invention is not limited to the above-described embodiment, and various modifications are possible .

For example , in one embodiment, both the wheel acceleration FGX and the slip ratio SX are corrected based on the extracted effective value MAG_FGX of the disturbance, but at least only the wheel acceleration FGX may be corrected.

[0055]

As described above, according to the anti-skid brake control method of the present invention, of the vibration components of the wheel acceleration, the components for a predetermined period after the start of the pressure reduction of the brake pressure, or the components and predetermined value or more components of a predetermined time period
Extracting dividing the removed component, based on the extracted vibration component, it is so arranged to correct the braking pressure control by the actuator, in particular, even at low μ road such as new snow,
Due to the slight vibration of the wheel acceleration caused by the disturbance, the brake pressure of the wheel is not undesirably reduced, and a stable braking force can be secured. Further, in the case of the present invention, since only the vibration component of the wheel acceleration caused by the disturbance need be extracted, the extraction can be performed simply and accurately.

[Brief description of the drawings]

FIG. 1 is a graph showing a change trend of a wheel speed and a vibration state of a wheel acceleration when an ABS is operated.

FIG. 2 is a graph showing a relationship between a road surface μ and a slip ratio.

FIG. 3 is a schematic view showing an anti-skid brake system (ABS).

FIG. 4 shows a hydraulic unit (H) of the above system.
It is the schematic which showed some U).

FIG. 5 is a block diagram showing a signal processing system of various sensors of the system.

FIG. 6 is a part of a functional block diagram illustrating an operation of an electronic control unit (ECU) of the system.

FIG. 7 is a diagram showing the rest of the functional block diagram of the ECU.

FIG. 8 is a diagram showing the principle of select row.

FIG. 9 is a block diagram illustrating a process of extracting a disturbance included in wheel acceleration.

FIG. 10 is a graph showing the vibration state of the wheel acceleration and the effective value of the extracted disturbance according to the disturbance extraction process.

FIG. 11 is a flowchart showing a main routine of the ABS.

FIG. 12 is a graph showing a vibration state of wheel acceleration without correction together with a change in brake pressure of the wheel.

FIG. 13 is a graph showing the vibration state of the wheel acceleration with the correction and the change in the brake pressure of the wheel.

[Explanation of symbols]

 2 Wheel cylinder 6 Hydraulic unit (HU) 10 Wheel speed sensor 14 Handle angle sensor 16 Front and rear G sensor 18 Electronic control unit (ECU) 20 Solenoid valve (actuator)

Claims (3)

(57) [Claims] 1. An anti-skid brake control method for controlling a brake pressure of a wheel by operating an actuator based on slip information of a wheel, the method comprising: anti which the disturbance extraction step of extracting the excluded component ingredients, based on the extracted vibration component from the disturbance extraction step, a correction step of correcting the brake pressure control by operation of the actuator, and feature by comprising Skid brake control method. 2. The anti-skid brake control method according to claim 1, wherein the predetermined period in the disturbance extracting step is a period corresponding to one cycle of the vibration of the wheel acceleration. 3. The method according to claim 1, wherein the disturbance extracting step includes a step of generating a vibration of the wheel acceleration.
Extract components that exclude components that are equal to or greater than a predetermined value.
3. The control method for an anti-skid brake according to claim 1, wherein: