JP2503245B2 - Anti-skid controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-skid control device for preventing wheel lock during braking of a vehicle, and particularly to detect vehicle body deceleration in order to estimate vehicle body speed. The present invention relates to a device suitable when equipped with an acceleration sensor.

[Prior Art] Conventionally, as this type of anti-skid control device, for example, the one described in JP-A-57-11149 is known. This device uses an acceleration (deceleration) sensor that detects deceleration in the longitudinal direction of the vehicle body and an anti-skid control start or braking start time in order to obtain the vehicle body speed required when calculating the slip ratio of the wheels. The wheel speed is used as an initial value, and the integrated value of the deceleration detection value is subtracted from this initial value to estimate the vehicle body speed.

[Problems to be Solved by the Invention]

However, in such a conventional device, for example,
The detected vehicle body deceleration may be smaller than the actual vehicle body deceleration due to the occurrence of gain change, drift, etc. of the acceleration sensor itself, and the error increases when performing continuous integration for a long time. Therefore, if such a situation occurs in the future, the estimated vehicle body speed is required to be higher than the actual vehicle body speed, and it is erroneously determined that the wheel slip ratio is higher than the actual slip ratio, and the brake pressure is maintained for a long time. Since the number of tires continues to decrease, there is a problem that the vehicle tends to have no brakes and adversely affects the braking performance.

The present invention has been made in view of such a problem, and in the control of the brake pressure, eliminates a situation in which the depressurized state lasts longer than necessary, thereby preventing a no-brake tendency and a no-brake state. Therefore, the improvement of braking performance is an issue to be solved.

[Means for solving the problem]

Therefore, in order to solve the above problems, in the device according to claim 1 of the present invention, as shown in FIG. 1 (a), a wheel speed detecting means for detecting a wheel speed and a wheel speed detection value based on this wheel speed detection value are used. Wheel acceleration / deceleration calculation means for calculating wheel acceleration / deceleration, vehicle body deceleration detection means for detecting vehicle deceleration, and vehicle body for estimating ground speed of the vehicle body based on the wheel speed detection value and the vehicle body deceleration calculation value Speed estimating means, slip ratio calculating means for calculating the slip ratio of the wheel based on the vehicle speed estimated value and the wheel speed detected value, and each of the slip ratio calculated value and the wheel acceleration / deceleration calculated value set in advance. In an anti-skid control device provided with a brake pressure control means for comparing with a reference value and controlling the brake pressure in at least pressure reducing, holding, and pressure increasing modes in accordance with the comparison result, In the brake pressure control means, a slip ratio reference value adjusting unit that moves the reference value in the direction of increasing the slip ratio from the time when the slip ratio matches the reference value when the slip ratio increases beyond the reference value. Is provided.

Further, in the apparatus according to claim 2, as shown in FIG. 1 (b), in addition to the above-mentioned configuration, the brake pressure control means is provided with the progress after the slip ratio matches a reference value for the slip ratio. A reference value reset control unit for resetting the reference value to its initial value when the time reaches a predetermined set value is added.

[Action]

According to the present invention, the ground speed of the vehicle body is estimated by the vehicle body speed estimating means based on the vehicle wheel speed detection value and the vehicle body deceleration calculation value obtained from the detected value, and the vehicle wheel speed is estimated based on the vehicle body speed estimation value and the vehicle wheel speed detection value. The slip ratio is calculated by the slip ratio calculating means. The brake pressure control means compares the slip ratio calculation value and the wheel acceleration / deceleration calculation value with respective preset reference values, and at least reduces, holds, and increases the brake pressure according to the comparison result.

At this time, in the brake pressure control means, when the slip ratio increases beyond the reference value for it, the slip ratio reference adjusting unit adjusts the reference value itself to increase the slip ratio from the time when the slip ratio matches the reference value. Move in the direction. As a result, the reference value will come to the return of the slip ratio due to the pressure reduction to the "small" side, so the pressure reduction command time will be shorter than when the reference value is fixed, and the pressure will continue to be reduced. The above problems due to are solved.

Further, in the apparatus according to claim 2, in particular, when the elapsed time reaches a predetermined set value after the slip ratio matches the reference value, the reference value reset control unit sets the reference value to the initial value. Reset to value. This prevents an excessive increase in the slip ratio reference value.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

2 to 5 are views showing an embodiment of the present invention.

In FIG. 2, reference numeral 2 denotes a hydraulic drum brake mounted on a vehicle, and reference numeral 4 denotes an anti-skid control device of the four-wheel independent control for the brake 2.

The brake 2 is a brake pedal 6, a master cylinder 8, and wheel cylinders of front left to rear right wheels 9FL to 9RR.
It has 10FL to 10RR.

The anti-skid control device 4 includes wheel speed sensors 11FL to 11RR for detecting a wheel rotation state, a longitudinal acceleration sensor 12 as a vehicle body deceleration detecting means for detecting acceleration in the longitudinal direction of the vehicle body, and detection values thereof. Based on the controller 15, the anti-skid control is commanded, and the control signal output from this controller 15 controls the wheel cylinder.
Actuator for adjusting hydraulic pressure of 10FL to 10RR 16FL to
It is configured to include 16RR.

Wheel speed sensors 11FL~11RR is formed by an electromagnetic pickup provided at a predetermined position of each wheel 9FL～9RR, respectively outputs a sine-wave alternating voltage signal v ₁ to v ₄ with a frequency proportional to the rotational speed of the wheel. Further, the longitudinal acceleration sensor 12 is provided at a predetermined position of the vehicle body, and is an acceleration (deceleration) signal G which is an analog voltage signal corresponding to the longitudinal acceleration (deceleration).
Output _x as positive for deceleration.

As shown in FIG. 3, the controller 15 (only the front left side and the common circuit are shown because the signal processing circuits on the front left side to the rear right side have the same configuration), the wheel speed sensor 11 is provided at its input stage.
Frequency / voltage (F / V) that converts the FL detection signal v ₁ into a voltage signal proportional to its frequency and uses this as the wheel speed signal V _w1
The converter 30 is provided. Here, the wheel speed sensor 11FL and the frequency / voltage converter 30 form a wheel speed detecting means 31.

The output side of the frequency / voltage converter 30 is a wheel deceleration side comparator 34 via a differentiator 32 as wheel acceleration / deceleration calculation means.
A reaches the comparison input end of the comparator 34B on the wheel acceleration side, the initial value input end of the integrator 35 as the vehicle speed estimating means, and the slip ratio calculating circuit 37 as the slip ratio calculating means.

A reference voltage signal −V ₂ and an acceleration reference value α ₁ (eg, 0.6G) corresponding to a wheel deceleration reference value −α ₂ (eg, −1G) are respectively applied to reference input terminals of both comparators 34A and 34B. ) Is applied to the reference voltage signal V ₁ . Therefore, the comparator 34A has a logic H level when _w1 ≦ −V ₂ , _w1 >
Outputs a logic L level signal when -V ₂
Outputs a logic H level signal when _w1 ≧ V ₁ and a logic L level signal when _w1 <V ₁ . Furthermore, this comparator 34
Output side of A, 34B is 4-input AN via inverters 44A, 44B
The output side of the inverter 44B reaches the 3-input AND circuit 50 as well as the D (logical product) circuit 46. Furthermore, the output of the deceleration side comparator 34A is input to the integrator 35 as a control input.

Further, the input side of the integrator 35 reaches the longitudinal acceleration sensor 12, and the output side thereof reaches the strip rate calculation circuit 37. The integrator 35 changes from the logic L level of the output of the comparator 34A to the logic H level.
Which operates the rise of the level as an operation start signal, a locking tendency instantaneous wheel speed V _w1 wheel deceleration speed signal _w1 reaches the reference value -V ₂ as an initial value, V _ref = V _w1 -∫G _x dt ... (1) is calculated to calculate the estimated vehicle speed signal V _ref . Further, the integrator 35 is configured to be supplied with a reset signal formed based on a brake switch signal or the like in response to the end of braking. So, when this reset signal is supplied, the integrator 35 force is configured to output V _ref = V _w1 .

The slip ratio calculation circuit 37 includes a subtractor and a divider, and inputs the estimated vehicle body speed signal V _ref and the wheel speed signal V
_{For w1} , The slip ratio signal S ₁ corresponding to the slip ratio of the front left wheel 9FL is calculated on the basis of the above equation and is output to the comparison input terminal of the comparator 54 at the next stage. The output side of the comparator 54 is connected to the AND circuit 46 via the AND circuit 50 and the inverter 56, respectively.

An output side of an integrator 58 as a slip ratio reference value adjusting section is connected to a reference input terminal of the comparator 54, and the integrated output is supplied. The initial value of the integrator 58 is set to a fixed reference value K ₀ (value corresponding to 15% of the slip ratio), and the input signal is set to a constant value β (positive value). The integral calculation of K = K ₀ + ∫βdt (2) is performed on K, and the variable reference value K that increases from the fixed reference value K _{0 with a} constant gradient (for example, 0.02 per unit time) is output, The initial value K ₀ is output when no operation is commanded. The integrator 58 uses the rising of the output of the comparator 54 to the logic H level as the integration start signal.

Further, the output side of the integrator 58 is also connected to the comparison input terminal of the comparator 60 as the reference value reset control unit, and the output of this comparator 60 is the reset input of the integrator 58.
At the reference input terminal of the comparator 60, in order to suppress an excessive increase in the slip ratio reference value K, a maximum reference value K'which is appropriately set is set.
Is applied. As a result, the output K of the comparator 60 becomes K.
To satisfy the ≧ K ', rises to a logic H level from the logic L level of the output until it output of the integrator 58 are configured to be reset to the initial value K ₀ is biased to this rise. When the integrator 58 is reset to the initial value K ₀ , the output of the comparator 60 returns to the logic L level and the reset state of the integrator 58 is maintained.

Therefore, the comparator 54 sets a logical H level when the slip ratio signal S ₁ ≧ K with respect to the slip ratio reference value K supplied as described above, and a logical L level when S ₁ <K. Is output.

By the way, the output side of the integrator 35 is also connected to the comparison input end of the comparator 72 for vehicle speed comparison, and the reference input end of the comparator 72 has a vehicle speed that can be regarded as a pseudo vehicle stop state (here In, a voltage signal V ₀ corresponding to 5 km / h) is applied. Then, the comparator 72 _{outputs a} logic H when V _ref ≧ V _0.
Level, if V _ref <V ₀ , AND circuit 50
And an RS flip-flop 74 at the set input.

The reset input terminal of the flip-flop 74 is connected to the output terminal of the AND circuit 50, and the Q output terminal of the flip-flop 74 reaches the AND circuit 46 via the OR circuit 76 in the subsequent stage. The output of the pulse generator 77 that generates the pulse signal P1 for the gradual pressure increase is the other input of the OR circuit 76.

Further, the output sides of the AND circuits 50 and 46 reach the outflow valve 91 and the inflow valve 90 of the actuator 16FL, which will be described later, via the amplifiers 78 and 80, respectively, whereby the hydraulic pressure control signals AV and EV are supplied to the respective valves 91 and 90.
Are supplied respectively. In other words, AND circuit 50
Outputs a signal of logic H level only when all of its three inputs are logic H level, and in response to this, the hydraulic pressure control signal AV
Is turned on, and the AND circuit 46 turns on the hydraulic pressure control signal EV only when all four inputs are at the logical H level.

Further, the output side of the AND circuit 50 has a retriggerable timer 81,
Through the amplifier 82, it reaches the pump 93 of the actuator 16FL, so that the pump control signal MR can be supplied. The retriggerable timer 81 outputs a logic H level set for a time longer than one skid cycle every time the output of the AND circuit 50 rises to a logic H level. Turns on.

On the other hand, each of the actuators 16FL to 16RR
As shown in the figure, an inflow valve 90 connected between the master cylinder 8 and the wheel cylinder 10FL (to 10RR), an outflow valve 91 connected to the wheel cylinder 10FL (to 10RR),
An accumulator 92 for accumulating and an oil pump 93 for oil recovery connected to the output side of the outflow valve 91, and a check valve 94 between the oil pump 93 and the master cylinder 8 are provided.

Of these, the inflow valve 90 and the outflow valve 91 are normally closed solenoid valves whose opening and closing are controlled by hydraulic pressure control signals EV and AV from the controller 15. In the pressure increasing mode, the control signal EV is turned on and the control signal AV is turned off, so that the inflow valve 90 is “open” and the outflow valve 91 is “closed”, so that the control hydraulic pressure from the master cylinder 8 flows in. It can be supplied to the wheel cylinder 10FL (to 10RR) via the valve 90, and as a result, the cylinder pressure rises. In the pressure reducing mode, the control signal EV is turned off and the control signal is turned on, the inflow valve 90 is closed and the outflow valve 91 is opened, and the wheel cylinder 10 is turned off.
The oil in FL (FL10RR) can be collected on the master cylinder 8 side, and as a result, the cylinder hydraulic pressure drops. Further, in the holding mode, by turning off the control signals EV and AV, the inflow valve 90 and the outflow valve 91 are closed, and the wheel cylinder FL (up to 10RR) is closed.
Oil can be confined and its pressure can be maintained. The control signal MR is turned on during the anti-skid control, whereby the pump 93 is driven.

Here, in the controller 15, a control unit 96 is formed by a circuit configuration excluding the frequency / voltage converter 30, the differentiator 32, the integrator 35, and the slip ratio calculation circuit 37.
The brake pressure control means is constituted by the actuator 16FL (to 16RR).

Next, the operation of the above embodiment will be described with reference to FIG. For the sake of simplicity, the wheel speeds are assumed to be the same for all four wheels 9FL to 9RR, and the front left side will be described.

This device starts when the ignition switch is turned on.

First, when the vehicle is running in a brake non-operating state where the wheel slip ratio is almost zero (before t ₀ ), the integrator 35 is in the reset state, and the wheel speed sensor 11FL corresponds to the wheel peripheral speed of the wheel 9FL. The sine wave signal v ₁ is output to the controller 15.

The input AC signal v ₁ is converted by the frequency / voltage converter 30 into a wheel speed signal V _w1 proportional to the frequency. This signal V _w1 is converted by the differentiator 32 into a wheel acceleration / deceleration signal _w1 which indicates the rate of change per minute time, and the comparator V
34A and 34B are compared with reference values −V ₂ and V ₁ , respectively, and comparators 34A and 34B
Both outputs of B are set to logic L level ((3) in FIG. 5)
(See (4)). Further, since the estimated vehicle speed signal V _ref = V _w1 is calculated in the slip ratio calculation circuit 37, the slip ratio S ₁ = 0 is calculated, and the output of the comparator 54 is a logical L level (see (7) in the same figure) and the inverter The output of 56 becomes a logic H level (see (11) in the figure). Further, since the vehicle is now traveling at a speed equal to or higher than the speed at which the vehicle is stopped, the output of the comparator 72 is at the logical H level (see (9) in the same figure), and the flip-flop 74 is set by this (( 12)), its Q output is a logic H level, and this is supplied to the OR circuit 76. On the other hand, the pulse signal P1 (refer to (13) in the figure) for gradually increasing the pressure from the pulse generator 77 is also supplied to the OR circuit 76, and its output becomes the logic H level.

Therefore, in one AND circuit 46, all of its four inputs are at the logic H level, so that the outputs are also at the logic H level (see (14) in the same figure), and the hydraulic pressure control signal for the inflow valve 90 of the actuator 16FL is predetermined. The level turns on. At this time, in the other AND circuit 50, of the three inputs, the comparator 54
The output of the AND circuit 50 is held at the logic L level because the output of the AND circuit is at the logic L level (see (10) in the same figure). Therefore, the hydraulic pressure control signal AV for the outflow valve 91 of the actuator 16FL is turned off at a zero level, the retriggerable timer 81 is not activated, and the pump control signal MR is turned off.

That is, in the normal traveling state, the inflow valve 90 is open and the outflow valve 91 is closed, and the oil from the master cylinder 8 can flow into the wheel cylinders 10FL (（10RR).

Further, in this normal running state, since the output of the comparator 54 is at the logical L level, the integration operation is not performed in the integrator 58, and the output of the integrator 58 is its initial value K ₀ . As a result,
The slip ratio reference value K for the comparator 54 is set to K = K ₀ (see (8) in the same figure).

From this state, assume that sudden braking is performed at time t ₀ . That is, when the brake pedal 6 is depressed, the wheel cylinder 10FL is passed from the master cylinder 8 through the inflow valve 90.
Oil flows into (~ 10RR), the cylinder pressure (brake pressure) suddenly increases (see (15) A in the same figure), the wheel speed begins to decrease (see (1) in the same figure), and the vehicle deceleration Is detected by the longitudinal acceleration sensor 12. As described above, even when the wheel speed is lower than the actual vehicle speed, the output of the comparator 34A is at the logical L level, the integration operation is not performed by the integrator 35, and the estimated vehicle speed signal V _ref = V Output _w1 and use this to calculate the slip ratio.

Then, along with this rapid increase, the differentiator wheel acceleration signal _w1 output by the 32 becomes a signal which gradually increases in the negative direction (see FIG. 2), at time t _1, the reference value -V deceleration side Reach ₂ Energized by this, the comparator 34A has a logic H level, the inverter 44A has a logic L level, and the AND circuit 46.
Becomes a logic L (see (3), (5) and (14) in the figure). In other words, the hydraulic pressure control signal EV is turned off (the signal AV is turned off) from the above-mentioned sudden pressure increase state, and the pressure is maintained (see (15) B in the same figure).

At the same time, at time t ₁ , the integrator 35 is urged by the output rise of the deceleration-side comparator 34A, and the estimated vehicle body speed signal V _ref according to the above-mentioned equation (1) relating to the vehicle body deceleration signal G _x. Is calculated and this is started to be supplied. This allows
When the wheels tend to lock, an accurate vehicle speed is estimated based on the vehicle body deceleration G _x .

Furthermore, although the decrease in the wheel speed V _w1 slows down due to this holding pressure, the calculated value of the slip ratio calculation circuit 37 becomes S ₁ = K ₀ at time t ₂ . As a result, the output of the comparator 54 becomes the logic H level, and all three inputs of the AND circuit 50 become the logic H level, so that the output also becomes the logic H level (see (7) and (10) in the same figure). When the pressure control signal AV turns on, the retriggerable timer 81 starts and the pump control signal
MR turns on. On the other hand, at this time, since the output of the AND circuit 46 is at the logical L level, the hydraulic pressure control signal EV is turned off, the above-mentioned pressure reduction mode is commanded, and the cylinder hydraulic pressure decreases ((15) in FIG. 5). (See C).

On the other hand, at the same time, at time t ₂ , the output of the comparator 54 is urged to rise to the logical H level, and the integral calculation of the integrator 58 based on the equation (2) is started. That is, the integrator 58 at the time of the lapse of the time t _2, the FIG (8)
As shown in, the variable reference value K that rises from the initial value K _{0 with a} constant gradient is output, and this becomes the reference value K in the comparator 54.

The pressure reduction process described above, the wheel acceleration and deceleration at time t _{3
Although w1} = −α ₂ is restored, the pressure reduction mode is continued because the recovery of the wheel speed V _w1 is not sufficient.

On the other hand, the slip ratio S ₁ has exceeded the variable reference value K since the start of depressurization, but decreases as the wheel speed V _w1 recovers,
At time t ₄ , S ₁ = K. In other words, the time t ₄ is the time arriving earlier than when the slip ratio reference value K and the fixed value K ₀ (see FIG. 8).

Therefore, at the time t ₄ , the output of the comparator 54 becomes the logic L.
The output level of the inverter 56 is inverted (see (7) and (11) in the figure). However, since the output K of the integrator 58 has not yet reached its maximum value K ', the increase of the variable reference value K continues as it is.

Then, in this case, the AD circuit 50 is at a logical L level, AND
The circuit 46 produces a pulsed output (see (10) and (14) in the same figure). In other words, while maintaining the hydraulic pressure control signal AV off,
The hydraulic pressure control signal EV is turned on for a predetermined minute time, and this is repeated in a predetermined cycle. As a result, Fig. 5 (15)
As shown by A ', the hydraulic pressure rises in a stepwise manner. That is, the control is such that the depressurization ends early and the pressure gradually starts to increase immediately.

The slow pressure increase is performed until time t ₅ as the wheel acceleration _w1 = V _1, then, is continued hold mode until the time t ₈ to be again _w1 = V _1.

At time t ₇ during this time, the input of the comparator 60 is K = K ′.
Therefore, the output rises to logic H. By being biased by this, the integrator 58 is reset, and thereafter outputs the initial value K ₀ again until t ₉ when the integration calculation is commanded. That is, the reference input K of the comparator 54 returns to the initial value K ₀ .

After that, by satisfying the same condition as described above,
Yuruzo圧(t ₈ ~t _9), vacuum (t ₉ ~t _10), holding pressure (t ₁₀ ~
t _11), reduced pressure (t ₁₁ ~t _12), Yuruzo圧(t ₁₂ ~t _13), holding pressure _{(t 13 ~t 14), ......} , repeated skid cycle with equal continues until complete braking. In the time t _10, again becomes the wheel deceleration _w1 = -V _2, since rises output again the logic H level of the comparator 34A, the integrator 35 is the wheel speed V _w1 at that time as an initial value Calculation is starting.

As described above, in the present embodiment, the reference value K for determining the magnitude of the slip ratio S ₁ is increased with the passage of time from the time point S ₁ = K ₀ , the pressure reduction mode is ended early, and the pressure increase is performed again. The mode is set. Therefore, even if the estimated vehicle speed V _ref becomes larger than the actual vehicle speed with the passage of integration time due to the detection error included in the detected value G _x of the longitudinal acceleration sensor 12, it is determined that the slip ratio is high. The time to be shortened is shortened by T in Fig. 5 (15), and the no-brake state can be prevented.

In addition, the controller 15 in the above-described embodiment may be entirely configured by a computer.

Further, the above embodiment shows a case where the present invention is applied to a drum type brake, but this is also applicable to a disk type brake. Further, it can be applied not only to the four-wheel independent control system but also to the two-wheel control anti-lock brake.

Further, the actuator for controlling the brake pressure is not limited to the above-mentioned embodiment, and for example, “BOSH TECHNISHE BERISHTE BANT7 HEFT2 ANTI B issued by BOSH in 1980.
The format described in "LOKIER SYSTEM (ABS)" can also be used.

〔The invention's effect〕

As described above, according to the present invention, when the slip ratio increases beyond the reference value for the slip ratio, the reference value is moved in the direction of increasing the slip ratio from the time when the slip ratio matches the reference value. Therefore, even when the estimated vehicle body speed becomes higher than the actual vehicle body speed due to some factor such as a detection error of the vehicle body deceleration detection means, such a situation is caused by the duration of the slip ratio being long or short. Therefore, it is possible to shorten the time when it is judged that the slip ratio is large and end the decompression earlier than in the case where the reference value is fixed as in the past, and as a result, it is possible to accelerate re-pressure increase. Therefore, it is possible to prevent the no-brake condition from occurring and eliminate the deterioration of the braking performance.

Further, in the apparatus according to claim 2, in addition to the effects described above,
It is possible to prevent the reference value from rising excessively, and to secure an appropriate range of the reference value that prevents the wheels from falling into a lock.

[Brief description of drawings]

1 (a) and 1 (b) are views corresponding to the claims of the present invention, FIG. 2 is a block diagram showing the overall configuration of an embodiment of the present invention, and FIG. 3 is a controller of FIG. FIG. 4 is a block diagram showing the configuration of the actuator of FIG. 2, FIG. 4 is a block diagram showing the configuration of the actuator of FIG. 2, and FIG. 5 is a timing chart showing the operation of each part of this embodiment. In the figure, 2 is a brake, 4 is an anti-skid control device, 9F
L ~ 9RR is wheel, 10FL ~ 10RR is wheel cylinder, 11FL ~
11RR is a wheel speed sensor, 12 is a longitudinal acceleration sensor (vehicle body deceleration detection means), 15 is a controller, 16FL to 16RR are actuators that form part of brake pressure control means, 31 is wheel speed detection means, and 32 is a differentiator ( Wheel acceleration / deceleration calculation means), 35
Is an integrator (vehicle body speed estimation means), 37 is a slip ratio calculation circuit (slip ratio calculation means), 58 is an integrator (slip ratio reference value adjustment unit), 60 is a comparator (reference value reset control unit),
Reference numeral 96 is a control unit forming a part of the brake pressure control means.

Claims (2)

(57) [Claims] 1. Wheel speed detecting means for detecting a wheel speed,
Wheel acceleration / deceleration calculation means for calculating the acceleration / deceleration of the wheel based on the wheel speed detection value, vehicle body deceleration detection means for detecting the deceleration of the vehicle body, and vehicle body based on the wheel speed detection value and the vehicle body deceleration calculation value. Body speed estimating means for estimating the ground speed, slip ratio calculating means for calculating the slip ratio of the wheel based on the vehicle speed estimated value and the wheel speed detection value, and the slip ratio calculated value and the wheel acceleration / deceleration calculated value An anti-skid control device comprising: a brake pressure control means for controlling the brake pressure in each mode of at least pressure reduction, holding, and pressure increase according to the comparison result. When the slip rate increases beyond the reference value for the brake pressure control means, the reference value is set at the time when the slip rate matches the reference value. An anti-skid control device characterized in that a slip ratio reference value adjusting unit for moving in the direction of increasing the lip ratio is provided. 2. A reference for causing the brake pressure control means to reset the reference value to its initial value when the elapsed time reaches a predetermined set value after the slip ratio matches the reference value for the brake pressure control means. The anti-skid control device according to claim 1, further comprising a value reset control unit.