JPH0516789A - Antiskid brake control method and device thereof - Google Patents

Abstract

PURPOSE:To provide a method to estimate a vehicle speed surely and accurately, in an antiskid brake control device. CONSTITUTION:The antiskid brake control device is constituted of a G sensor 7, a control circuit 6 to which signals from respective wheel speed sensors 3a-3d are input, and a hydraulic actuator 5 driven based on the computed signals in the control circuit 6. The brake pressure of respective wheel cylinders 2a-2d are controlled based on a target slip ratio computed in the control circuit 6, from the deceleration of a vehicle body detected with the G sensor 7 and the wheel speed signals from the respective wheel speed sensors 3a-3d. Consequently, at searching the target slip ratio, by using the deceleration from the G sensor in addition to the directly detected wheel speeds, even in case of simultaneous speed drop of four wheels, the target slip ratio can be nearly equal to the actual slip ratio, and the brake force and cornering force aimed by ABS control itself can be insured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle anti-skid brake control device, and more particularly to a vehicle anti-skid brake control device capable of accurately calculating a wheel slip ratio to reliably brake a vehicle body.

[0002]

2. Description of the Related Art As is known, an anti-skid brake control device prevents the wheels from being locked even when the vehicle is suddenly braked on a slippery road surface to prevent skid of the wheels. That is, the anti-skid brake control device is configured to stop the vehicle stably without losing the braking performance by temporarily reducing the brake pressure when the wheels are about to lock.

In such control for preventing wheel lock (hereinafter referred to as ABS control), what is particularly important is how accurately the actual vehicle body speed during braking, which is difficult to measure directly even now, is accurately measured. It can be estimated. As a general method of estimating the vehicle body, for example, it is assumed that the lock occurs only in a part of the wheel,
A method is known in which the rotation speed of each wheel of a vehicle is detected and the highest speed among them is set as the vehicle speed (this is called the select high principle).

However, according to this conventional method, for example, when all wheels are locked at the start of ABS control and the wheel speeds of all the four wheels fall at the same time, the vehicle speed estimated from the detected wheel speeds is It will fall with the wheel speed, and a large difference will occur with the actual vehicle speed. In this case, the calculated slip ratio becomes larger than the actual slip ratio, so that it is not possible to secure the braking force of the vehicle and the cornering force that is the lateral stabilizing force even during the ABS control. there were.

Therefore, a method of utilizing the deceleration of the vehicle body for estimating the vehicle body speed has been disclosed in, for example, Japanese Patent Laid-Open No. 61-89156. That is, in this method for estimating the vehicle body speed, the acceleration g actually applied to the vehicle body is detected by the acceleration detector, the acceleration signal is integrated through the arithmetic circuit including the integrator, and the integrated signal is calculated. Subtract from the output signal from the speed detector (ie add -g)
This is to estimate the deceleration of the vehicle body.

[0006]

However, such a conventional vehicle speed estimation method has a problem that the vehicle speed cannot be estimated when the sign of the deceleration (negative value) is reversed. there were. Specifically, for example, when the vehicle body moves backward, the sign (polarity) of the output signal from the acceleration detector is reversed, which increases the estimated value of the vehicle body speed and rather estimates it as acceleration. Will end up. Further, especially in the case of a vehicle with a manual transmission, if the vehicle is suddenly braked with the clutch engaged, the wheel speed of the drive wheels will vibrate due to the torsional vibration of the drive system, and this vibration will be included in the estimation of the vehicle speed. Since the wheel speed is added, the vehicle speed is estimated to be a value larger than the actual vehicle speed.

The above-mentioned problems also occur when the acceleration detector is attached in the opposite direction by mistake.

In view of the above-mentioned problems in the prior art, the object of the present invention is to ensure the speed of the vehicle body without fail, even when the vehicle body is retracted or when the mounting direction of the acceleration detector is wrong. It is to provide an anti-skid brake control method and an apparatus therefor capable of estimating, and further, even in a vehicle with a manual transmission, an accurate vehicle speed is estimated to ensure reliable anti-skid brake braking. (EN) It is possible to provide a reliable and reliable anti-skid brake control method and its device.

[0009]

That is, according to the present invention, the above object is achieved by treating the deceleration used when estimating the vehicle body speed as an absolute value.

That is, the anti-skid brake control method proposed by the present invention determines the braking means for braking by the brake fluid pressure, the wheel speed detecting means for detecting the wheel speed of the vehicle, and the brake fluid pressure of the braking means. An estimated vehicle body speed in a vehicle having brake fluid pressure control means for controlling, control means for supplying a control signal to the brake fluid pressure control means, and at least one vehicle deceleration detecting means for detecting deceleration An anti-skid brake control method for controlling the brake fluid pressure by comparing the actual rotation state of the wheel and the wheel to prevent skid of the wheel by suppressing the excessive brake that causes the wheel lock. Determining the vehicle body speed based on the detection signal, and subtracting the deceleration signal of the deceleration detecting means from the determined vehicle body speed Thus estimating the vehicle speed, the time of the estimation, as the reducer speed signal using a anti-skid brake control method of taking the absolute value.

Further, the anti-skid brake control device proposed by the present invention controls the brake fluid pressure by comparing the estimated vehicle speed and the actual rotation state of the wheel to suppress the excessive brake that causes the wheel lock. An anti-skid brake control device for preventing skid of wheels by means of braking means for braking by brake fluid pressure, wheel speed detecting means for detecting wheel speed of a vehicle, and brake fluid pressure of the braking means. Brake fluid pressure control means,
A control means for supplying a control signal to the brake fluid pressure control means and at least one vehicle deceleration detection means for detecting deceleration, wherein the control means is detected by the vehicle deceleration detection means. The vehicle body speed estimating means for estimating the speed of the vehicle using the vehicle deceleration, the vehicle body speed estimating means determines the vehicle body speed based on the detection signal from the wheel speed detecting means, and The vehicle speed is estimated by subtracting the deceleration signal of the deceleration detecting means from the determined vehicle speed, and the deceleration signal used in the estimation is an anti-skid brake control device that takes an absolute value. is there.

Further, the anti-skid brake control device proposed by the present invention controls the brake fluid pressure by comparing the estimated vehicle speed and the actual rotation state of the wheel, and suppresses excessive braking that causes wheel lock. And an anti-skid brake control device for preventing skid of the wheels, braking means for braking by the brake fluid pressure, wheel speed detection means for detecting the wheel speed of the vehicle,
It has brake fluid pressure control means for controlling the brake fluid pressure of the braking means, control means for supplying a control signal to the brake fluid pressure control means, and at least one vehicle deceleration detection means for detecting deceleration. In the above, the control means is
The vehicle deceleration detecting means for estimating the vehicle speed using the vehicle deceleration detected by the vehicle deceleration detecting means, and the vehicle body speed estimating means is based on the detection signal from the wheel speed detecting means. The vehicle speed is determined by subtracting the deceleration signal of the deceleration detecting means from the determined vehicle speed, and the sign of the deceleration signal to be used is always predetermined. The anti-skid brake control device is provided with a means for converting to the code of.

In addition, the object is achieved by not using the drive wheel speeds for the estimation of the vehicle body speed, in particular to solve the problems in vehicles with a manual transmission.

[0014]

That is, according to the present invention described above, since the deceleration is the amount of change in the vehicle speed per unit time, the vehicle speed is estimated by using the deceleration as an analog value. The target slip ratio can be calculated even when the four wheels are about to lock at the same time, which is difficult to estimate by itself.At the same time, by treating the detected deceleration as an absolute value, regardless of the traveling direction of the vehicle body. Alternatively, even if the mounting direction of the acceleration detecting means is wrong, the ABS control can be accurately performed.

Further, by not using the driving wheel speed for estimating the vehicle body speed, it is possible to eliminate the fluctuation of the wheels due to the driving force when the wheels are locked, and therefore, without disengaging the clutch in a vehicle with a manual transmission. Even when it is difficult to estimate the vehicle body speed such as sudden braking, the vehicle body speed can be accurately estimated. As a result, the ABS control can ensure the desired braking force and cornering force.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 schematically shows an antiskid brake control device according to an embodiment of the present invention.

In the figure, wheel cylinders 2a to 2d and wheel speed sensors 3a to 3d are installed on the wheels 1a to 1d of the vehicle, respectively. The hydraulic pressure supplied to the wheel cylinders 2a to 2d generates a pressure in the master cylinder 4 by operating a brake pedal 8 shown in the figure, transmits the pressure to the hydraulic unit 5, and further the hydraulic unit 5 is driven. Through the above wheel cylinders 2a to
The pressure is transmitted to 2d. This hydraulic unit 5
For example, each wheel cylinder 2a ...
Control the hydraulic pressure of 2d.

Regarding the control of the hydraulic pressure of each wheel cylinder described above, the specific content thereof will be described in detail with reference to the attached FIG. First, the hydraulic unit 5 has solenoid valves 5a to 5h for conducting, holding, and releasing the hydraulic pressure transmitted to each wheel cylinder.
Are arranged, and these receive a control drive signal from the control circuit 6. Further, these solenoid valves 5a to 5h are so-called on / off valves, and are configured to control the hydraulic pressure of each wheel cylinder in pairs. That is, in the illustrated hydraulic control device, reference numerals 5a, 5c,
The solenoid valves 5e and 5g are controlled by the control drive signal from the control circuit 6, and their currents are turned on.
When, the oil passage is cut off, and when the current is off, it is turned on. Conversely, reference numerals 5b, 5d, 5f, 5
The solenoid valve indicated by h makes the oil passage conductive when the current is on, and shuts it off when the current is off. That is, the hydraulic pressure of the wheel cylinder 2a is such that when no current flows through both the solenoid valves 5a and 5b, the oil passage is brought into conduction with the master cylinder 4 via the solenoid valve 5a, and at the same time, the solenoid valve is closed. 5b is shut off. At that time, the hydraulic pressure of the master cylinder 4 is directly transmitted to the wheel cylinder 2a (this state is
"Pressurization mode").

On the other hand, when a current flows through the solenoid valve 5a, the oil passage between the solenoid valve 5a and the master cylinder 4 is cut off, and the hydraulic pressure in the wheel cylinder 2a is held (this state is called "holding mode"). Called). When a current flows through both the solenoid valves 5a and 5b, the oil passage of the solenoid valve 5a remains closed while the oil passage of the solenoid valve 5b remains conductive. At this time, the hydraulic pressure of the wheel cylinder 2a passes through the electromagnetic valve 5b and is released via the pump 10a driven by the motor 9 (this state is referred to as a "pressure reduction mode"). The motor 9 is driven by a signal from the control circuit 6 when the ABS operates, and drives the pumps 10a and 10b to be connected to release the hydraulic pressure of the wheel cylinder 2a to the master cylinder 4. Other wheel cylinders 2b, 2
The hydraulic pressures of c and 2d are similarly controlled.

Next, the ABS operation for sending signals of "decompression", "holding" and "increase" to the hydraulic unit 5 will be described with reference to FIG.
And it demonstrates using FIG. First, as a basic operation of the ABS, the vehicle body speed V is obtained from the wheel speeds Vfr, Vfl, Vrr, Vrl obtained by the wheel speed sensors 3a to 3d. Here, for example, Vfr: front right wheel wheel speed Vfl: front left wheel wheel speed Vrr: rear right wheel wheel speed Vrl: rear left wheel wheel speed.

Furthermore, each wheel speed Vf obtained as described above
From r, Vfl, Vrr, Vrl, and vehicle speed V, the slip ratio of each wheel is calculated by the following formula.

Sfr = (V-Vfr) / V: Front right wheel slip ratio (Equation 1) Sfl = (V-Vfl) / V: Front left wheel slip ratio (Equation 2) Srr = (V-Vrr) / V: Rear right wheel slip ratio (Equation 3) Srl = (V−Vrl) / V: Rear left wheel slip ratio (Equation 4) Therefore, the relationship between the friction coefficient and the lateral drag coefficient shown in FIG. 4 with respect to the slip ratio (μ−S, τ) -S characteristic), the brake fluid pressure of each wheel is controlled so that the wheel friction coefficient μ and the lateral drag coefficient τ simultaneously become a slip ratio in a range showing a high value. That is, as is clear from the figure, the slip ratio S is 0.
When it is in the vicinity of 1 to 0.2, the braking force and the cornering force can be fully utilized, and therefore the brake fluid pressure of each wheel is controlled so that the slip ratio S takes a value in the vicinity thereof.

More specifically, the slip ratios Sfr and Sf of each wheel obtained by the above (formula 1) to (formula 4).
When l, Srr, and Srl are in this range (S is 0.1 to 0.2) or more, the braking force is excessive, and therefore the wheel speeds Vf detected by the wheel speed sensors 3a to 3d.
r, Vfl, Vrr, and Vrl are too low. In such a case, the control circuit 6 outputs a control drive signal for the solenoid valves 5a to 5h so that the solenoid valves 5a to 5h are in the pressure reducing mode, and operates the solenoid valves 5a to 5h to reduce the brake fluid pressure. To reduce the slip ratio. On the other hand, when the slip ratio is within this range (S is 0.1 to 0.2), the solenoid valve 5a
By operating 5h to the pressure increasing mode and increasing the brake fluid pressure, each wheel speed is suppressed, and thus the slip ratio is increased to ensure a predetermined slip ratio. As described above, in the anti-skid brake control device according to the present invention, the slip ratio S is controlled by operating the solenoid valves 5a to 5h with the control circuit 6.

Further, the control circuit 6 has the above-mentioned AB
As one of the conditions for entering the S control, a so-called stop lamp 11 signal is input. Further, when the system is abnormal, the warning lamp 12 shown in the figure is turned on, and further, the fail-safe relay 13 is turned on / off according to the situation.

As described above, the ABS control is the so-called wheel slip ratio S which is an optimum value (for example, S
Is controlled to 0.05 to 0.2), so it is important how to accurately determine the slip ratio S. By the way, this slip ratio S is expressed by the above-mentioned equations (1) to (4).
As is clear from the figure, the vehicle body speed V and the wheel speeds Vfr, V
It is calculated from fl, Vrr, and Vrl. By the way, the wheel speeds Vfr, Vfl, Vrr, Vrl can be directly detected by the wheel speed sensor 3a.
Currently, the means for directly detecting is not practically used and is not generalized. Therefore, the ABS control device currently commercialized employs a method (select high method) of estimating the highest speed among the detected rotation speeds of the wheels as the speed of the vehicle body.

However, the problem with this vehicle speed estimation method (that is, the select high method) is that the ABS
In the case where the wheel speeds drop simultaneously at the start of the control, that is, when the four wheels of the vehicle slip at the same time at the start of the ABS control. This will be described with reference to the attached FIG.

First, when the ABS control is started due to the slip of the wheels, the wheel speeds of the four wheels of the vehicle fall at the same time. In FIG. 5, for example, the wheel speed of one of the plurality of wheels of the vehicle is represented by VW. In this case, in the method of estimating the wheel speed of the above-mentioned conventional technique as the vehicle speed (that is, the select high method), when the four wheels of the vehicle slip at the same time, the estimated vehicle speed V1 also falls together with the wheel speed VW. Therefore, the difference between the actual vehicle body speed V0 and the estimated vehicle body speed V1 (V1: for example, the wheel speed detected from the wheel by the above-described select high method) becomes large. In that case, the calculated slip ratio S1 and the actual slip ratio S0 are calculated by the following equations.

S0 = (V0-VW) / V0 (Equation 5) S1 = (V1-VW) / V1 (Equation 6) Then, between these calculated slip ratio S1 and actual slip ratio S0, The following relationship holds.

S0> S1 (Equation 7) That is, the obtained slip ratio S1 becomes a considerably smaller value than the actual slip ratio S0. Then, the slip ratios Sfr, Sfl, Srr, Srl of the respective wheels obtained by the above-mentioned (Equation 1) to (Equation 4) in the control circuit.
Is different from the actual value (S0), and we intend to control it to the optimum slip ratio in the range of 0.05 to 0.2 shown by the shaded area in Fig. 4, but it is actually outside this range. Therefore, the control is performed in the vicinity of the low slip ratio S0, and with this, the required braking force and cornering force cannot be obtained, and the stability of the vehicle body during braking cannot be ensured.

Therefore, the braking force is weakened or strengthened at each wheel speed during ABS control,
As shown in FIG. 6, the wheel speed repeatedly falls and recovers (this is referred to as a skid cycle). However, paying attention to the fact that the wheel speed does not become higher than the vehicle body speed during braking, and each wheel speed during this skid cycle is The vehicle body speed is estimated by connecting the maximum value of, that is, the mountain portion.

The method for estimating the vehicle body speed will be described in more detail with reference to FIG. That is, in the figure, the vehicle body speed is the maximum value (point b) after the wheel speed V starts to drop (point a) and once exceeds the minimum value, and the estimated vehicle body speed is obtained by connecting the point a and this point b. Next, the vehicle body speed is estimated by connecting the subsequently appearing maximum point c and the above point b, and continuing this work thereafter.

A problem with the above method of estimating the vehicle body speed is that the vehicle body speed cannot be estimated until the next peak of the wheel speed appears. That is,
From the maximum point b to the maximum point c, the vehicle body speed is estimated with the same inclination until the maximum point c appears as an extension of the estimated vehicle speed up to that point (extending the inclination from the point a to the maximum point b). You can also think of a way to proceed. However, even by such a method, the estimation cannot be performed immediately after the ABS control is started (for example, point a), and there is a problem that is the same as the select high method described above. It should be noted that, in FIG. 6, the wheel speed is considered to be only one wheel in order to simplify the description, but in reality, one wheel or more (four wheels or
Since it is estimated by the wheel speed of the wheels, the distance between the peaks will be narrowed, but it will still be impossible to estimate.

Therefore, according to the present invention, attention is paid to the fact that the deceleration is the amount of change in the vehicle body speed per unit time, that is, the inclination of the vehicle body speed shown in FIG. The deceleration (that is, the negative acceleration) detected by the acceleration sensor (G sensor) 7 that is a means for detecting the deceleration of the vehicle body is added to each control cycle (when the deceleration side is negative). It becomes possible to ask. If the above is specifically expressed by an equation, the vehicle speed can be estimated by the following equation.

Vbody = Vbody + Gbody (Equation 8) Vbody: Estimated vehicle body speed Gbody: Vehicle body deceleration (negative on deceleration side) As a result, even when the distance between the wheel ridges is long, the G sensor is used between the ridges. The vehicle speed can be estimated based on the detected deceleration, and the estimated vehicle speed does not drop together with the wheel speed even at the start of the ABS control, which is the most problematic. The slip ratio of each wheel also reduces the braking force during braking. It is possible to control the slip ratios Sfr, Sfl, Srr, and Srl of the respective wheels to be in the vicinity of 0.05 to 0.2 so that the cornering force can be sufficiently secured.

Even in the above vehicle speed estimating method, however, when the detected value of the deceleration detected by the G sensor 7 is used as it is for estimating the vehicle speed, for example, when the mounting direction of the sensor is wrong, or When the vehicle is suddenly braked when the vehicle moves backward, the value of the deceleration Gbody detected by the G sensor 7 becomes a positive value (the same value as during acceleration), which makes it impossible to estimate the vehicle speed. Therefore, when it is necessary to estimate the vehicle speed, that is, ABS
Paying attention to the fact that the vehicle behavior during operation is usually during sudden braking,
In the present invention, it is determined that the acceleration detected by the G sensor 7 is a deceleration (that is, it must be a negative value), and even if it is a positive value, it is set to a negative value. That is, the detected deceleration value is converted into an absolute value to eliminate the influence of the sign direction (positive or negative value).

FIG. 1 is a flow chart showing a concrete method of estimating the vehicle body speed in the control circuit 6 of the anti-skid brake control device according to the principle of the present invention. According to this estimation method, when the wheel speed is a mountain portion, that value is used as the vehicle body speed, and when it is not a mountain portion, the deceleration (absolute value) detected as an analog value by the G sensor 7 is used when moving forward or backward. Regardless of this, it is possible to accurately estimate the vehicle speed.

The contents of this flowchart will be described below. The tasks shown in this chart are, for example, 1
It is executed by a timer interrupt at regular intervals of a cycle of ms. According to this flowchart, first, in step 101, it is determined whether or not the brake is depressed to determine the start of the anti-skid brake control. That is, it is determined whether or not the brake switch for detecting the depression of the brake is on. If the result of this determination is "Yes", it is determined in step 102 whether the wheel speed is at the maximum. The determination as to whether or not the peak is the maximum is made as follows. First, when the wheel speed starts decreasing, a flag indicating deceleration is set. on the other hand,
When the wheel speed starts to increase, a flag indicating acceleration is set. Then, when these two flags are set and the deceleration of the wheels is 0 or more, it is determined as "mountain".

Next, when the wheel speed is the maximum value, that is, "Yes" is determined in this step 102, the maximum value is ended using the wheel speed. On the other hand, when it is determined in step 102 that the wheel speed is a portion other than the maximum portion, that is, “No”, the direction of the deceleration detected as an analog value by the G sensor 7 in step 103 ( If it is determined that it is positive (Gbody> 0) (that is, if it is determined as “Yes”), step 104 is performed.
The sign of the deceleration detected in 1 is reversed by an equation: Gbody = −Gbody (Equation 9) Further, in step 105,
Estimate the vehicle speed (vehicle speed) Gbody.

Vbody = Vbody + Gbody (Formula 10) On the other hand, if “No” is determined in Step 101, the flow moves to Step 105, and the speed of the vehicle body is estimated by the following formula.

Vbody = (| Vfr | + | Vfl |) / 2 (Equation 11) Further, in a vehicle with a manual transmission, when sudden braking is performed with the clutch engaged, as shown in FIG. The wheel speed detected due to the vibration also vibrates and shows a value larger than the actual vehicle speed. If this value is used for estimating the vehicle body speed, the estimated vehicle body speed also becomes a value larger than the actual vehicle body speed, and a difference occurs between the target slip rate and the actual slip rate,
As described above with reference to FIG. 4, the slip ratio becomes S0 instead of S1, and the braking force and the cornering force that are originally desired to be secured cannot be obtained. Therefore, according to one embodiment of the present invention, the driving wheel speed, which is easily influenced by the driving system, is not used for estimating the vehicle speed, and this problem is solved. Using the vehicle body speed obtained as described above, that is, the slip ratio is obtained from the deviation between the vehicle body speed and the wheel speed of each wheel, and the braking force, that is, the brake hydraulic pressure is adjusted so that this slip ratio becomes a predetermined value. Controlling is the same as in the above-mentioned conventional technique.

[0041]

As is apparent from the above description of the present invention, according to the anti-skid brake control method and the apparatus thereof according to the present invention, the causes such as the wrong mounting of the sensor and the traveling direction (backward traveling) of the vehicle body are caused. Nevertheless, it is possible to make the estimated vehicle speed almost equal to the actual vehicle speed from the start of the ABS control. Therefore, the target slip ratio and the actual slip ratio can be made to be almost equal, so that the braking force and the cornering force can be changed. The excellent effect of being able to reliably secure the target will be exhibited.

[Brief description of drawings]

FIG. 1 is a control flow chart for explaining a vehicle speed estimation operation which is a feature of the anti-skid brake control device of the present invention.

FIG. 2 is a system configuration diagram showing an outline of an apparatus for carrying out an anti-skid brake control method which is an embodiment of the present invention.

FIG. 3 is an input / output relationship diagram of a control circuit used in the antiskid brake control device of the present invention.

FIG. 4 is a μ-s, τ-s characteristic diagram showing the relationship between the slip ratio, the friction coefficient, and the lateral drag coefficient for explaining the operating principle of the anti-skid brake control method of the present invention.

FIG. 5 is a time series diagram of speed for explaining an operating state of the anti-skid brake control device.

FIG. 6 is another speed time series diagram for explaining the operating state of the anti-skid brake control device.

FIG. 7 is a time series diagram showing the states of the wheel speeds of the driving wheels and the driven wheels of the vehicle and the estimated vehicle body speed before using the present invention.

[Explanation of symbols]

2 ... Wheel cylinder, 3 ... Wheel speed sensor, 4 ... Master cylinder, 5 ... Hydraulic actuator, 6 ... Control circuit, 7 ...
G sensor.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hayato Sugawara             2477 Kashima Yatsu, Katsuta City, Ibaraki Prefecture             3 Hitachi Automotive Engineering             Within the corporation (72) Inventor Kosaku Shimada             2520, Takaba, Katsuda City, Ibaraki Prefecture             Hitachi, Ltd. Automotive Equipment Division

Claims (4)

[Claims] 1. Braking means for braking with brake fluid pressure, wheel speed detecting means for detecting wheel speed of a vehicle, brake fluid pressure control means for controlling brake fluid pressure of the braking means, and the brake fluid pressure. What has a control means for supplying a control signal to the control means and at least one vehicle deceleration detection means for detecting a deceleration, and compares the estimated vehicle body speed with the actual rotation state of the wheels to obtain the brake fluid. An anti-skid brake control method for controlling pressure, suppressing excessive braking that causes wheel locking, and preventing skid of a wheel, wherein the vehicle body speed is determined based on a detection signal from the wheel speed detecting means, and , The vehicle speed is estimated by subtracting the deceleration signal of the deceleration detection means from the determined vehicle speed, and at the time of estimation, the deceleration signal to be used is determined. Anti-skid brake control method characterized by taking the absolute value. 2. An anti-skid brake control device for controlling a brake fluid pressure by comparing an estimated vehicle speed with an actual wheel rotation state to suppress an excessive brake causing a wheel lock and prevent a skid of the wheel. Therefore, braking means for braking with brake fluid pressure, wheel speed detection means for detecting vehicle wheel speed, brake fluid pressure control means for controlling brake fluid pressure of the braking means, and brake fluid pressure control means A control means for supplying a control signal to the vehicle and at least one vehicle deceleration detecting means for detecting the deceleration, wherein the control means uses the vehicle deceleration detected by the vehicle deceleration detecting means. A vehicle body speed estimating means for estimating the vehicle speed by means of the vehicle body speed estimating means, and the vehicle body speed estimating means determines the vehicle body speed based on a detection signal from the wheel speed detecting means, The vehicle body speed is estimated by subtracting the deceleration signal of the deceleration detecting means from the determined vehicle body speed, and the deceleration signal used in the estimation takes an absolute value. Anti-skid brake control device. 3. The anti-skid brake control device according to claim 2, wherein the vehicle body speed estimating means determines the vehicle body speed by utilizing the wheels of the vehicle other than the driving wheels. . 4. An anti-skid brake control device for controlling the brake fluid pressure by comparing the estimated vehicle speed and the actual rotation state of the wheel to suppress excessive braking that causes wheel lock and prevent wheel skid. Therefore, braking means for braking with brake fluid pressure, wheel speed detection means for detecting vehicle wheel speed, brake fluid pressure control means for controlling brake fluid pressure of the braking means, and brake fluid pressure control means A control means for supplying a control signal to the vehicle and at least one vehicle deceleration detecting means for detecting the deceleration, wherein the control means uses the vehicle deceleration detected by the vehicle deceleration detecting means. A vehicle body speed estimating means for estimating the vehicle speed by means of the vehicle body speed estimating means, and the vehicle body speed estimating means determines the vehicle body speed based on a detection signal from the wheel speed detecting means, And a means for estimating the vehicle body speed by subtracting the deceleration signal of the deceleration detecting means from the determined vehicle body speed, and further for always converting the sign of the deceleration signal to be used into a predetermined sign. The anti-skid brake control device is characterized in that