JPH05221296A - Method for calculating car body speed estimated - Google Patents

Abstract

PURPOSE:To high accurately calculate an estimated car body speed, which serves as a creating reference of a control threshold value of antiskid control, by correcting one of an acceleration or deceleration limit value corresponding to a tilt angle of a road surface detected by a tilt angle sensor. CONSTITUTION:A car body speed arithmetic part 53 calculates a car body speed Vs output to an antiskid control part 52 and a friction coefficient decision part 54 by using a speed of a wheel with the least slip of the wheels. The friction coefficient decision part 54 decides a friction coefficient mu between the wheel and a road surface based on the car body speed Vs and each wheel speed Vw, to output a decision result of the friction coefficient to the antiskid control part 52. A car body deceleration correcting part 55 is provided in the car body speed arithmetic part 53, to input an output from a tilt angle sensor 3, which detects a tilt angle theta of the road surface, through an input processing circuit 56. The car body deceleration correcting part 55 corrects a deceleration limit value DELTAVsd corresponding to the tilt angle theta, and the car body speed arithmetic part 53 calculates the estimated car body speed Vs from the wheel speed Vw by using the corrected deceleration limit value DELTAVsd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating and calculating a vehicle body speed used for antiskid control or the like from wheel speeds.

[0002]

2. Description of the Related Art An anti-skid control device reduces the braking hydraulic pressure to restore the wheel speed when the wheel braking force becomes too large and the wheel is locked, and the slip ratio between the wheel and the road surface is This is a device for maintaining a value at which a high friction braking force acts. Therefore, in order to determine whether or not the wheels are about to lock, a slip reference created based on the vehicle body speed is determined, and when the slip reference is reached, the pressure reduction control is started. However, the vehicle speed is calculated based on the wheel speed,
Therefore, in order to eliminate the influence of the wheel speed, which has a relatively large fluctuation range, in a typical conventional technique, the vehicle speed is estimated and calculated as follows.

That is, the previous estimated vehicle speed is Vs (i
−1), the current vehicle body speed Vsi is Vs (i
-1)-? Vsd to Vs (i-1) +? Vsu. Here, ΔVsu is the acceleration limit value and ΔVsd is the deceleration limit value. When the vehicle speed is estimated and calculated at regular time intervals, the maximum vehicle speed change range is 1 G (G is a gravitational acceleration) due to factors such as the coefficient of friction μ between the wheels and the road surface during deceleration. When driving, the value will not exceed that value. During acceleration, the maximum value is about 0.5G due to engine performance and the like. Therefore, the acceleration limit value ΔVsu and the deceleration limit value ΔVsd can be obtained by multiplying the respective maximum values during acceleration / deceleration as described above by the calculation cycle. By estimating the vehicle body speed Vs from the acceleration limit value ΔVsu thus obtained within the range of fluctuation of the deceleration limit value ΔVsd, the vehicle body speed Vs is estimated with high accuracy from the wheel speed Vw having a large fluctuation range. be able to.

[0004]

As described above, the limit value of deceleration during normal running is about 1.0 G. However, in the typical prior art, a certain control margin is ensured, for example, 1. It is set to about 1G. This is because when the deceleration of the actual vehicle body speed is larger than the deceleration of the estimated vehicle body speed Vs, the difference between the estimated vehicle body speed Vs and the wheel speed Vw becomes large and the slip ratio becomes large, which is erroneously determined. This is to prevent a problem in which the braking hydraulic pressure is reduced and sufficient braking force cannot be secured even though the wheels are not locked. Therefore, during unstick control on a flat road, the deceleration limit value ΔVsd becomes too large, and the accuracy of calculating the estimated vehicle body speed Vs deteriorates.

An object of the present invention is to provide a vehicle body speed estimation calculation method capable of obtaining an estimated vehicle body speed with high accuracy.

[0006]

According to the present invention, when the vehicle body speed is estimated and calculated corresponding to the output from the wheel speed sensor in each predetermined calculation cycle, the previously estimated vehicle body speed V is calculated.
s (i-1) and the estimated vehicle speed Vs (i-2) two times before
And an upper limit value Vsu and a lower limit value Vsd are set for the current estimated vehicle speed Vsi, which is estimated from the difference ΔVs between the two, and the acceleration limit value Δ that determines the upper limit value Vsu and the lower limit value Vsd in advance.
Vsu and deceleration limit value ΔVsd are calculated by the following equations, respectively,

[0007]

## EQU1 ## Vsu = Vs (i-1)-. DELTA.Vs + .DELTA.Vsu

[0008]

## EQU00002 ## Vsd = Vs (i-1)-. DELTA.Vs-.DELTA.Vsd The current wheel speed V detected by the wheel speed sensor.
wi, an intermediate value of the upper limit value Vsu and the lower limit value Vsd is selected to be the estimated vehicle body speed Vsi at this time, in the method for estimating the vehicle body speed, in accordance with the inclination angle of the road surface detected by the inclination angle sensor, A method for estimating and calculating a vehicle body speed, comprising correcting at least one of an acceleration limit value ΔVsu and a deceleration limit value ΔVsd.

The deceleration limit value ΔVsd of the present invention is
When the inclination angle on the down road surface is θ, the deceleration limit value K on the flat road is

[0010]

## EQU00003 ## It is characterized in that it is obtained by correcting with .DELTA.Vsd = K (cos .theta.-sin .theta.).

[0011]

According to the present invention, when the estimated vehicle body speed Vs is obtained from the wheel speed Vw, first, the difference between the previous value Vs (i-1) of the vehicle body speed and the value Vs (i-2) two times before is measured. ΔVs is calculated. From this difference ΔVs, the vehicle speed Vs
Can be identified.

On the other hand, there is a limit to the amount of change in the vehicle body speed Vs due to road surface conditions, engine performance, etc. Therefore, when obtaining the estimated vehicle body speed Vs, the limit value ΔVsu during acceleration and the limit value ΔVsd during deceleration are determined. Is set. The acceleration limit value ΔVsu and the deceleration limit value ΔVsd
And the above-mentioned difference ΔVs, the previously estimated vehicle body speed Vs
The upper limit value Vsu and the lower limit value Vsd of the estimated vehicle body speed Vs that can be allowed for (i-1) are calculated by the following equations, respectively.

[0013]

## EQU1 ## Vsu = Vs (i-1)-. DELTA.Vs + .DELTA.Vsu

[0014]

## EQU00002 ## Vsd = Vs (i-1)-. DELTA.Vs-.DELTA.Vsd The upper limit value Vsu and the lower limit value Vsd thus obtained,
An intermediate value with the current wheel speed Vwi is selected as the current estimated vehicle speed Vsi. That is, when Vwi> Vsu, the upper limit value Vsu is set to the estimated vehicle body speed Vsi, and when Vsd ≦ Vwi ≦ Vsu, the wheel speed Vwi is set to the estimated vehicle body speed Vsi, and further Vwi is set.
When <Vsd, the lower limit value Vsd is set to the estimated vehicle body speed Vsi. Thus, the previous estimated vehicle speed V
s (i-1) and the estimated vehicle speed Vs (i-2) two times before
The upper limit value Vsu and the lower limit value Vsd are set in consideration of the tendency of the change of the estimated vehicle speed Vsi using the difference ΔVs from

At least one of the acceleration limit value ΔVsu and the deceleration limit value ΔVsd is corrected according to the inclination angle of the road surface detected by the inclination angle sensor. That is, for example, the inclination angle on the down road surface is θ,
When the deceleration limit value on a flat road is K, the deceleration limit value ΔVs
d is

[0016]

## EQU3 ## ΔVsd = K (cos θ-sin θ)

Therefore, for example, on an asphalt road surface having a relatively high friction coefficient and on an uphill road where the inclination angle θ has a negative polarity, the deceleration limit value ΔVsd is corrected to be larger than the value K on a flat road. Therefore, the limit value K during normal traveling on a flat road can be set to a relatively small value, and the vehicle body speed Vs can be estimated and calculated with high accuracy.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a functional block diagram for explaining the principle of one embodiment of the present invention. Wheels 34a to be described later
34d is provided with wheel speed sensors 1a to 1d, and the wheel speed pulse from each of these wheel speed sensors 1a to 1d is, in the wheel speed calculation unit 51, a wheel speed representing the wheel speed and wheel acceleration of each wheel. After being converted into a signal, it is input to the anti-skid control unit 52.

The wheel speed signal from the wheel speed calculating section 51 is used as a vehicle speed calculating section 53 and a friction coefficient determining section 5.
4 are input respectively. The vehicle speed calculation unit 53
The vehicle body speed Vs is calculated using the wheel speed of the wheel with the least slip among the wheels 34a to 34d as described later, and is output to the anti-skid control unit 52 and the friction coefficient determination unit 54, respectively. The friction coefficient determination unit 54 determines, based on the vehicle body speed Vs and each wheel speed Vw,
The friction coefficient μ between the wheel and the road surface is determined, and the determination result is output to the antiskid control unit 52.

A vehicle body deceleration correction unit 55 is provided in the vehicle body speed calculation unit 53. To the vehicle body deceleration correction unit 55, an inclination angle θ of the road surface is input via an input processing circuit 56.
The output from the tilt angle sensor 3 for detecting is input. The vehicle body deceleration correction unit 55 corrects the deceleration limit value ΔVsd for obtaining the estimated vehicle body speed Vs, as will be described later, corresponding to the inclination angle θ. The vehicle body speed calculation unit 53 uses the corrected deceleration limit value ΔVsd to calculate the estimated vehicle body speed Vs from the wheel speed Vw.

The anti-skid controller 52 is shown in FIG.
As shown by, the slip reference indicated by reference numeral L2 is set on the basis of the estimated vehicle speed Vs, and each wheel is detected while the switch 7 detects that the brake pedal 30 to be described later is depressed. When the speed Vw becomes equal to or lower than the slip reference L2, a pressure reducing signal is derived to the actuators 13a to 13d such as solenoid valves provided in the brake hydraulic pressure piping path to reduce the brake hydraulic pressure as shown in FIG. 2 (2). Then, the anti-skid control is performed in this way.

When the wheel speed Vw is recovered by the pressure reduction control, the anti-skid control unit 52 increases the braking hydraulic pressure in accordance with the recovery acceleration and the friction coefficient μ determined by the friction coefficient determination unit 54. As described above, the pressure increasing signal is output to the actuators 13a to 13d. In this way, the braking hydraulic pressure is reduced, increased, or maintained, and the slip ratio between the wheel and the road surface is controlled to always be an optimum value to shorten the braking distance.

The tilt angle sensor 3 is realized by, for example, an acceleration sensor, and detects the tilt angle θ as follows. FIG. 3 is a diagram for explaining a method of detecting the inclination angle θ on the down road surface by the inclination angle sensor 3. The inclination angle sensor 3 is attached so as to detect the longitudinal acceleration F3 of the vehicle body 61. On the other hand, the vertical acceleration F1 of 1 G, which is gravitational acceleration, acts on the vehicle body 61 traveling at a constant speed. Therefore, the inclination angle θ can be obtained from the equation 4.

[0024]

## EQU00004 ## .theta. = Sin.sup.- ¹ (F2 / F1) When the road surface 62 has a downward slope, the acceleration F3 acts in a direction to accelerate the vehicle body 61. Further, the force F2 acting in the vertical direction on the road surface 62 is 1 G which is the gravitational acceleration when the road surface 62 is a flat road, but becomes smaller as the inclination angle θ increases, and in this case, This is equivalent to a decrease in the load on the road surface 62 and therefore a decrease in the friction coefficient μ. Therefore, the friction coefficient determination unit 54 also corrects the determination result of the friction coefficient μ according to the inclination angle θ obtained as described above. That is, for example, even if it is determined that the road is a medium μ road,
When the inclination angle θ is equal to or greater than a predetermined value, the determination result is corrected to a high μ road.

FIG. 4 is a timing chart for explaining the calculation procedure of the estimated vehicle body speed Vs using the inclination angle θ. Predetermined calculation cycle W from the current time ti
1. Let t (i-1) be the time of the previous calculation timing that is 1, 4 msec before, for example, and let t (i-2) be the time of the previous calculation timing that is the previous time W1. The estimated vehicle speed at time t (i-2) is V
s (i-2), the estimated vehicle speed at time t (i-1) is Vs (i-1), and the difference ΔVs between the two, that is, the deceleration when the vehicle is being decelerated is first calculated. Next, the difference ΔVs from the estimated vehicle body speed Vs (i-1).
Is subtracted, that is, the deceleration is added to decelerate at a constant deceleration ΔVs, and the estimated vehicle body speed Vsa at the current time ti is obtained.

Further, the deceleration limit value ΔVsd determined by the friction coefficient μ of the road surface is subtracted with the estimated vehicle body speed Vsa as a reference, and the lower limit value V of the estimated vehicle body speed Vs is subtracted.
sd is required. Further, the estimated vehicle body speed Vsa is added to the acceleration limit value ΔVsu determined by engine performance or the like.
Is added to obtain the upper limit value Vsu.

That is, the upper limit value Vsu and the lower limit value Vsd are respectively expressed by the following equations.

[0028]

## EQU1 ## Vsu = Vs (i-1)-. DELTA.Vs + .DELTA.Vsu

[0029]

## EQU00002 ## Vsd = Vs (i-1)-. DELTA.Vs-.DELTA.Vsd The upper limit value Vsu and the lower limit value Vsd thus obtained.
The estimated vehicle body speed Vsi at this time is determined based on the wheel speed Vwi of the selected wheel so as to be within the range. That is, the upper limit value Vsu, the lower limit value Vsd, and the wheel speed V
An intermediate value of the values of wi is used as the estimated vehicle body speed Vsi. Therefore, when Vwi> Vsu, the estimated vehicle body speed Vsi is set to the upper limit value Vsu, and when Vsd ≦ Vwi ≦ Vsu, the estimated vehicle body speed Vsi is set to the selected wheel speed Vwi, and Vwi is set.
When <Vsd, the lower limit value Vsd is set for the estimated vehicle body speed Vsi. The selected wheel speed Vwi
Among the wheel speeds of the four wheels 34a to 34d, the minimum value is used during acceleration and the maximum value is used during deceleration in order to remove the influence of slip.

On the other hand, when the deceleration limit value ΔVsd is K, which is the deceleration limit value on a flat road,

[0031]

## EQU00003 ## The correction is made by .DELTA.Vsd = K (cos .theta.-sin .theta.). The deceleration limit value K can be represented by the product of the vertical acceleration F1 shown in FIG. 3 and the cycle W1. Therefore, the equation 4 is

[0032]

## EQU00005 ## .DELTA.Vsd = (F1.times.W1) .times. (Cos .theta.-sin .theta.), For example .theta. = 10 degrees, and if the period W1 is 4 msec as described above, the deceleration limit value .DELTA.Vsd is 0.05 (m / m). sec). In this way, the deceleration limit value K on the flat road is corrected according to the inclination angle θ,
The deceleration limit value ΔVsd on the slope is obtained.

Therefore, at the time of deceleration on a downhill with the inclination angle θ of 10 degrees, the deceleration limit value K on a flat road is used for the actual change of the vehicle body speed indicated by the reference symbol Vsr in FIG. The estimated vehicle body speed changes as indicated by the reference symbol Vsk. On the other hand, the estimated vehicle speed using the deceleration limit value ΔVsd to which the inclination angle is corrected according to the present invention changes as indicated by the reference symbol Vs. The deceleration gk, which is the gradient of the estimated vehicle body speed Vsk, is 1.0 G as described above, and the deceleration gs of the estimated vehicle body speed Vs is 0.81 G. On the other hand, the deceleration gw of the wheel speed Vw is 20G. As described above, by correcting the deceleration limit value ΔVsd in accordance with the inclination angle θ of the road surface 62, the estimated vehicle body speed Vs can be obtained with high accuracy, the fluctuation range of the braking hydraulic pressure is small, and the responsiveness is good. Antiskid control can be performed.

The road surface 62 was downhill,
When it is an uphill slope, the inclination angle θ has a negative polarity and therefore ΔVsd> K. As a result, when the vehicle is traveling uphill with a high friction coefficient μ such as asphalt, the deceleration limit value ΔVsd becomes larger than on a flat road, and the estimated vehicle body speed Vs can also be obtained with high accuracy. Although only the limit value ΔVsd is corrected corresponding to the inclination angle θ, as another embodiment of the present invention,
Similar correction may be performed on the acceleration limit value ΔVsu.

The inclination angle sensor 3 may directly obtain the inclination angle of the road surface 62 by using a level or the like, instead of obtaining the inclination angle from the longitudinal acceleration of the vehicle body 61 as described above.

FIG. 5 is a block diagram showing the electrical construction of the anti-skid control device in which the present invention is implemented.
FIG. 4 is a piping route diagram of a braking hydraulic pressure of the anti-skid control device. The wheel speed sensors 1a to 1d provided on the wheels 34a to 34d detect the rotation speeds of the wheels 34a to 34d, respectively.

These wheel speed sensors 1a-1d are, for example, in the circumferential direction of a ferromagnetic detection plate fixed to the wheel shaft.
A large number of notches and protrusions are provided at equal intervals, and a wheel speed signal having a frequency proportional to the rotation speed of the wheel is derived by an electromagnetic pickup or an optical sensor provided near the circumference of the detection plate. Has been done. The wheel speed signals from the wheel speed sensors 1a to 1d are given to the waveform shaping circuits 5a to 5d in the antiskid control circuit 4,
The waveform is shaped into a pulse signal and then input to the processing circuit 2.

The output signal of the tilt angle sensor 3 is given to the analog / digital conversion circuit 6 and converted into a digital value, and then given to the processing circuit 2 to be subjected to digital filter processing for removing unnecessary components. Be seen. Processing circuit 2
Are the inclination angle sensor 3 and the wheel speed sensor 1
The anti-skid control is performed by performing arithmetic processing based on the outputs from a to 1d.

The processing circuit 2 also includes a brake pedal 30.
The output from the switch 7 that detects that the
The level conversion circuit 8 controls the antiskid control circuit 4
It is input after being converted to a suitable voltage level within. In each circuit in this anti-skid control circuit 4,
The voltage from the battery 11 input via the power switch 10 is stabilized by the power circuit 9 and then supplied.

The processing circuit 2 uses a three-position electromagnetic control valve 32, which will be described later, based on the input result input as described above.
The actuators 13a to 13d configured by a to 32d and the wheel cylinders 33a to 33d are drive-controlled to perform an antiskid control operation. That is, the relay coil 15a of the relay 15 is excited via the solenoid relay drive circuit 14, whereby the relay switch 1
5b becomes conductive. Via this relay switch 15b
A high level voltage is commonly applied to one input of each of the actuators 13a to 13d. Control outputs from the processing circuit 2 are given to the other inputs of the actuators 13a to 13d via the solenoid drive circuits 12a to 12d, respectively. As a result, the three-position electromagnetic control valves 32a to 32d control the braking hydraulic pressure to either a pressure-increasing or pressure-decreasing state or a holding state as described later.

Further, the processing circuit 2 outputs the output to the relay coil 16a of the relay 16 via the motor relay drive circuit 18, and thereby the motor for generating the braking hydraulic pressure is connected to the relay switch 16b of the relay 16. 17
Are driven and controlled. Furthermore, the processing circuit 2 turns on the warning lamp 19 via the lamp driving circuit 20 when an abnormality occurs in the anti-skid control.

Referring to FIG. 6, when the brake pedal 30 is stepped on, braking hydraulic pressure is generated in the master cylinder 31, and the braking hydraulic pressure passes through the pipe lines P1 to P4 and the three-position electromagnetic control valve is operated. 32a to 32d, and the pipe P
It is supplied to the wheel cylinders 33a to 33d via 5 to P8. As a result, the wheels 34a to 34d are braked and the vehicle body speed is reduced.

The rotation speeds of the wheels 34a to 34d are respectively detected by the wheel speed sensors 1a to 1d and input to the antiskid control circuit 4. An output signal representing the longitudinal acceleration of the vehicle body detected by the tilt angle sensor 3 is also input to the antiskid control circuit 4.

When the anti-skid control circuit 4 determines that the condition for starting the anti-skid control is satisfied, the braking hydraulic pressure generated by the motor 17 is transferred to the conduit P.
9 to the master cylinder 31, and the three-position electromagnetic control valves 32a to 32d are controlled to either increase pressure, reduce pressure, or hold the wheel cylinders 33a to.
The braking hydraulic pressure of 33d is controlled. As a result, the wheels 34
The slip ratios a to 34d are controlled to values at which a high friction braking force acts on the road surface.

FIG. 7 is a flow chart for explaining the antiskid control operation. In step n1, initialization processing is performed, and in step n2, for example, the above-mentioned 4
It is determined whether or not a predetermined arithmetic operation timing for every msec has come, and when the arithmetic operation timing comes, the process moves to step n3. At step n3, each wheel speed Vw is calculated from the detection result of each wheel speed sensor 1a-1d. In step n4, the inclination angle θ of the road surface 62 is calculated from the detection result of the inclination angle sensor 3 on the basis of the equation 4. In step n5, the above-mentioned equations 1 to 3 and 5
The estimated vehicle body speed Vs is calculated using. Step n
In 6, the coefficient of friction μ between the wheel and the road surface is determined.
When the parameters for the anti-skid control are obtained in this way, the control of the braking hydraulic pressure, which will be described later, is performed in step n7.

FIG. 8 is a flow chart for explaining the control operation of the braking hydraulic pressure in step n7 in detail. When the anti-skid control operation is executed, it is judged in step s1 whether or not the anti-skid control is currently executed. If not, step s
At 2, it is determined whether or not the conditions for starting the anti-skid control are satisfied. The control start condition is, for example, when the wheels 34a to 34d are locked, or when the wheel speed is equal to or less than the slip reference L2.

When the anti-skid control start condition is satisfied, the process proceeds to step s3, and the wheel cylinders 33a to 33 are placed in a predetermined memory area of the processing circuit 2.
A decompression flag for causing d to perform the decompression operation is set, and the process proceeds to step s4. In the step s1,
If anti-skid control has already been performed, the process directly goes to step s4. In step s4, it is determined whether or not the condition for ending the anti-skid control is satisfied. The control termination condition is, for example, when the operation of the brake pedal 30 is released, or when the vehicle body speed becomes 5 km / h or less.

When the anti-skid control termination condition is satisfied in step s4, and the above step s
When the anti-skid control start condition is not satisfied in step 2, the process proceeds to step s18, and the actuator 1
The three-position electromagnetic control valves 32a to 32d of 3a to 13d are set to the pressure increasing position, and the antiskid is not controlled. Therefore, the braking hydraulic pressure generated in the master cylinder 31 by the depression of the brake pedal 30 is transmitted to the wheel cylinders 33a to 33d, and the normal braking operation is performed.

In step s4, if the antiskid control termination condition is not satisfied, step s
5, the flag for controlling the increase / decrease in the braking hydraulic pressure of the wheel cylinders 33a to 33d is determined. At the start of the anti-skid control, the pressure reduction flag is set as shown in step s3, so step s
Go to 6. In step s6, it is determined whether or not the pressure reducing control should be ended. If not, in step s7, the pulse width control of the pressure reducing pulse is performed, the ratio between the pressure reducing output and the holding output is changed, and the operation is ended.

When the pressure reduction control should be terminated in step s6, that is, when the wheel speed starts to recover, the process proceeds to step s8 and the wheel cylinders 33a ...
The holding flag for keeping the braking hydraulic pressure of 33d constant is set, and the routine goes to Step s9. Such an anti-skid control operation is repeated, and when the holding flag is already set in step s5, the process also goes to step s9. In step s9, it is determined whether or not the holding end condition is satisfied. If not, in step s10, the three-position electromagnetic control valves 32a to 32d are set to the holding positions to perform the holding control, and then the operation ends.

In step s9, if the holding end condition for judging that the wheel speed has recovered is satisfied, the pressure increase flag for increasing the braking hydraulic pressure of the wheel cylinders 33a to 33d is set in step s11, Move to step s12. If the pressure increase flag has already been set in step s5, the process directly goes to step s12. In step s12, it is determined whether or not the pressure increase termination condition is satisfied. If not, in step s13, after the three-position electromagnetic control valves 32a to 32d are set to the pressure increase position and the pressure increase control is performed. , Ends the operation.

This pressure increasing control is performed based on the peak value of the wheel acceleration recovered by the pressure reducing control and the friction coefficient μ set in step n6.
Is higher and the peak value of acceleration is higher, the amount of pressure increase is increased. The pressure increase termination condition is, for example, a case where the pressure increase time determined by the wheel acceleration obtained when the wheel speed is recovered has elapsed.

When the condition for ending the pressure increase is satisfied in step s12, the process proceeds to step s14, the pulse pressure increasing flag for gently increasing the braking hydraulic pressure in the wheel cylinders 33a to 33d is set, and the process proceeds to step s15. .. If the pulse pressure increase flag is already set in step s5, the process directly goes to step s15. In this step s15, it is judged whether or not the ending condition of the pulse pressure increasing control is satisfied,
If not, in step s16, the pulse pressure increasing control of the three-position electromagnetic control valves 32a to 32d is continued and the operation is ended. When the condition for ending the pulse pressure increasing control is satisfied in step s15, step s17
After the depressurization flag is set at, the process proceeds to step s7 and depressurization control is performed.

[0054]

As described above, according to the present invention, at least one of the acceleration limit value ΔVsu and the deceleration limit value ΔVsd is corrected according to the inclination angle of the road surface detected by the inclination angle sensor. , For example, deceleration limit value ΔVs
When d is corrected, the deceleration limit value ΔVsd greatly changes in accordance with the inclination angle even on an uphill slope having a high friction coefficient such as asphalt. Therefore, the deceleration limit value ΔVsd on a flat road can be set to a relatively small value, and thus the estimated vehicle body speed Vs can be set.
It is possible to improve the estimation accuracy of the upper limit value Vsu and the lower limit value Vsd, and to obtain the estimated vehicle body speed Vs with high accuracy.

[Brief description of drawings]

FIG. 1 is a functional block diagram for explaining the principle of an embodiment of the present invention.

FIG. 2 is a diagram showing changes in vehicle body speed Vs and wheel speed Vw with respect to changes in braking hydraulic pressure during anti-skid control.

FIG. 3 is a diagram for explaining a method of calculating an inclination angle θ of a road surface 62.

FIG. 4 is a timing chart for explaining how to obtain an estimated vehicle body speed Vs.

FIG. 5 is a block diagram showing an electrical configuration of an anti-skid control device in which the present invention is implemented.

FIG. 6 is a piping route diagram of a braking hydraulic pressure of the anti-skid control device.

FIG. 7 is a flowchart for explaining an anti-skid control operation.

FIG. 8 is a flow chart for explaining a control operation of braking hydraulic pressure in detail.

[Explanation of symbols]

 1a to 1d Wheel speed sensor 2 Processing circuit 3 Tilt angle sensor 4 Antiskid control circuit 13a to 13d Actuator 51 Wheel speed calculation unit 52 Antiskid control unit 53 Vehicle body speed calculation unit 54 Friction coefficient determination unit 55 Vehicle body deceleration correction unit

Claims (2)

[Claims] 1. When performing an estimation calculation of a vehicle body speed corresponding to an output from a wheel speed sensor for each predetermined calculation cycle, a previous estimated vehicle body speed Vs (i-1) and an estimated vehicle body speed Vs two times before. The upper limit value Vsu and the lower limit value Vsd are provided to the estimated vehicle speed Vsi of this time estimated from (i-2) and the difference ΔVs between the two, and the upper limit value Vsu and the lower limit value Vsd are set.
And acceleration limit value ΔVsu and deceleration limit value ΔVs
d and Vs = Vs (i-1) -ΔVs + ΔVsu Vsd = Vs (i-1) -ΔVs-ΔVsd This time detected by the wheel speed sensor. Wheel speed V
wi, an intermediate value of the upper limit value Vsu and the lower limit value Vsd is selected to be the estimated vehicle body speed Vsi at this time, in the method for estimating the vehicle body speed, in accordance with the inclination angle of the road surface detected by the inclination angle sensor, A method for estimating and calculating a vehicle body speed, which comprises correcting at least one of an acceleration limit value ΔVsu and a deceleration limit value ΔVsd. 2. The deceleration limit value ΔVsd is obtained by correcting the deceleration limit value K on a flat road by the following equation: ΔVsd = K (cos θ−sin θ), where θ is an inclination angle on the downhill road surface. The method for estimating and calculating the vehicle body speed according to claim 1, which is obtained.