JPH0952572A - Antilock brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably achieve the antilock braking even on different traveling road surface by detecting the vibration characteristic of a wheel speed, and controlling the braking force to be applied to wheels so as to realize the slip ratio below the value in which the road surface friction coefficient is approximately the peak value based on the detected result. SOLUTION: A control part to control a vehicle motion system 22 to control the braking force to be applied to wheels is provided with a braking force excitation part to give fine vibration to the braking force Pd by an operation part 24 by an operator, and a braking force reduction part to suppress the increase in the braking force based on the resonance characteristics of the wheel speed. The braking force excitation part operates the amplitude value Pv of fine amplitude of the braking command Pb based on the detected value ωd from an amplitude detecting part 23, and also operates the braking force reduction command Pr based on the data ωd , Pv . A driver 27 generates the braking command which is the input to the vehicle motion system 22 to be controlled based on the data Pd , Pv , Pr .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antilock brake control device, and more particularly to a wheel rotation speed (wheel speed).
The present invention relates to an anti-lock brake control device that controls a braking force based on a vibration characteristic appearing in [1] and performs a braking operation at a friction coefficient between a wheel and a road surface having a maximum value (peak [mu]).

[0002]

2. Description of the Related Art A conventional anti-lock brake control device creates a vehicle speed, a vehicle acceleration / deceleration, or a speed signal close to the vehicle speed based on a signal from a wheel speed sensor,
Based on these comparisons, the anti-lock braking operation is performed by controlling the braking force.

That is, in Japanese Unexamined Patent Publication No. 61-196853, a comparison is made between an estimated estimated vehicle speed and a reference speed obtained from the wheel speed or the like to determine whether or not the wheel may be locked, An anti-lock brake controller is described that reduces the braking force when there is a possibility of locking. In this antilock brake control apparatus, the estimated vehicle speed v _v is obtained by connecting the troughs of the velocity v _w determined from the wheel speed as shown in FIG. 1 at a constant rate, the estimated vehicle speed v _v and the actual vehicle body It can be understood that there is a deviation from the velocity v _{v *} .

Further, in this anti-lock brake control device, in order to prevent the estimated vehicle speed v _v by a change in the wheel ground load during running on a rough road becomes larger actual vehicle speed v _{v *,} the estimated vehicle speed When the wheel speed changes more than the change, the increase rate of the estimated vehicle speed is suppressed.

When a vehicle is traveling at a certain speed,
Although slipping occurs between the wheel and the road surface as the brake is applied, the friction coefficient μ between the wheel and the road surface is as shown in FIG. 2 against the slip ratio S represented by the following equation (1). It is known to change to. Note that v _{v *} is the actual vehicle speed, and v _w is the wheel speed.

S = (v _{v *} −v _w ) / v _{v *} (1) In this μ-S characteristic, the friction coefficient μ has a peak value at a certain slip ratio (A2 region in FIG. 2). become. If the slip ratio having the peak value is known in advance, the slip ratio can be controlled by obtaining the slip ratio from the vehicle speed and the wheel speed.

Therefore, in the anti-lock brake control device of Japanese Patent Laid-Open No. 1-249559, the slip ratio is calculated from the approximate value of the vehicle speed and the wheel speed, and the calculated slip ratio is compared with the set slip ratio. It controls the braking force. In this anti-lock brake control system, in order to prevent the long a state of no-brake by the deviation between the estimated vehicle speed v _v and the actual vehicle speed v _{v *,} a long time brake pressure than necessary in a reduced pressure state I try not to.

As shown in FIG. 3, these conventional anti-lock brake control systems use a vehicle body speed estimating unit for estimating a vehicle body estimated speed v _v from wheel speed ω _w and vehicle body acceleration v _v '(= dv _v / dt). 2 and a braking force control unit 3 that detects the locked state of the wheels from the wheel speed ω _w and the vehicle body estimated speed v _v and controls the braking force P _b for the driving system 1 of the vehicle.

[0009]

However, in such a conventional anti-lock brake control device, since the vehicle body speed estimating unit is required, as shown in FIG. must velocity calculated v _w and the actual vehicle speed v _{v *} returns the braking force until a match or a near value, for this purpose it is necessary to repeat at a relatively low frequency the pressure increasing decompression braking forces of the wheels It was Also,
Since the vehicle speed compared to the reference speed is an approximate value obtained from the wheel speed, vehicle acceleration / deceleration, etc., it may differ greatly from the actual vehicle speed, and in some cases the wheels may be locked for a long time or may not return. Therefore, there was a problem that the braking force was extremely reduced. As a result, the behavior of the vehicle may be significantly affected, resulting in an increase in braking distance and unpleasant vibration.

Furthermore, in an anti-lock brake control device that controls the braking force based on the slip ratio, it can be easily predicted that the slip ratio, which is the maximum friction coefficient, differs depending on the road surface condition on which the vehicle is running. It is necessary to detect and estimate the condition and prepare a plurality of reference slip ratios according to the road surface condition, or change the reference slip ratio according to the road condition.

The present invention has been made in order to solve the above-mentioned conventional problems, and does not detect the locked state of the wheel based on the comparison of the wheel speed and the vehicle speed or the comparison of the slip ratio, and also the μ-S characteristic. It is possible to provide an antilock brake control device capable of stably performing an antilock brake operation even on different road surfaces without estimating the vehicle body speed by detecting a change in the vibration characteristic of the wheel speed determined by To aim.

[0012]

In order to achieve the above object, the invention of claim 1 is to detect a vibration characteristic of wheel speed between a detecting means and a tire and a road surface based on the detected vibration characteristic. The control means controls the average braking force acting on the wheels so that the friction coefficient becomes a slip ratio equal to or less than the peak value.

According to the first aspect of the invention, as described in the second aspect, it is possible to further provide an excitation means for minutely exciting the braking force acting on the wheel at a predetermined frequency.

According to a third aspect of the present invention, the resonance frequency detecting means for obtaining the resonance frequency from the frequency distribution of the wheel speed, and the control for reducing the average braking force acting on the wheel when the resonance frequency is higher than the reference value. And a control means for controlling.

It is preferable that the control means of the invention according to claim 3 controls so as to increase the average braking force when the resonance frequency is lower than the reference value.

The resonance frequency detecting means of the invention of claim 3 is
The frequency when the amplitude value of the vibration component of the wheel speed can be determined as the resonance frequency, in this case, the resonance frequency detection means, conversion means for converting the wheel speed to frequency series data, An extraction unit that extracts the frequency when the amplitude is maximum as the resonance frequency.

Further, according to the invention of claim 4, as shown in FIG. 4, an exciting means 7 for minutely exciting the braking force acting on the wheel at the resonance frequency of the vibration system constituted by the vehicle body, the wheel and the road surface, Detecting means 5 for detecting the amplitude of the resonance frequency component of the wheel speed, and an average value which acts on the wheel when the gain of the amplitude of the resonance frequency component of the wheel speed with respect to the amplitude of the minute excitation of the braking force is smaller than the reference value. And a control means 6 for controlling so as to reduce the braking force.

It is preferable that the excitation means of the invention of claim 4 minutely excite the braking force controlled by the driver at the same frequency as the resonance frequency of the wheel speed when the tire is gripped.

It is effective that the control means of the present invention detects the amplitude of the wheel speed by obtaining the correlation between the wheel speed and the single sine wave of the resonance frequency of the wheel speed.

According to a fourth aspect of the present invention, the detecting means is connected to the wheel speed detecting means for detecting the wheel speed and the wheel speed detecting means, and the resonance of the wheel speed when the tire is gripped in the pass band. It can be configured by a bandpass filter set in a predetermined range including a frequency and a DC converting means for converting the bandpass filter output into DC and outputting the DC output.

Further, it is preferable that the control means of the invention of claim 4 controls so as to increase the average braking force when the gain is larger than the reference value.

According to a fourth aspect of the present invention, the control means calculates the gain of the amplitude of the resonance frequency component of the wheel speed with respect to the amplitude of minute excitation of the braking force, and calculates the deviation between the gain and the reference value. Calculating means, a PI control means for outputting a reduced braking force command for performing proportional-plus-integral control based on the deviation, and a positive control of the reduced braking force command so as not to be instructed beyond the braking force operated by the driver. Positive value removing means for removing the value and outputting only a negative value as a reduced braking force command for reducing the average braking force acting on the wheels.

Further, the control means of the invention of claim 4 comprises: a calculating means for calculating the gain of the amplitude of the resonance frequency component of the wheel speed with respect to the amplitude of the minute excitation of the braking force; and the gain when the tire is not locked. A storage means for storing, a calculation means for calculating a difference between the gain calculated by the calculation means and a gain stored in the storage means, and a calculation means for calculating a deviation between the difference and the reference value, PI control means for outputting a reduced braking force command for performing proportional-plus-integral control based on the deviation, and removing a positive value of the reduced braking force command so as not to be commanded beyond the braking force operated by the driver. And a positive value removing means for outputting only a negative value as a reduced braking force command for reducing the average braking force acting on the wheels.

Further, in the invention of claim 4, as described in claim 5, physical quantity detecting means for detecting a vehicle speed or a physical quantity related to the vehicle speed is further provided, and the vehicle speed or the vehicle speed detected by the physical quantity detecting means is related. Depending on the physical quantity,
The reference value may be changed.

In this case, it is effective to decrease the reference value as the vehicle speed or the physical quantity related to the vehicle speed increases.

According to a sixth aspect of the present invention, excitation means for minutely exciting the braking force acting on the wheel at the resonance frequency of the vibration system constituted by the vehicle body, the wheel and the road surface and at a constant amplitude,
Detecting means for detecting the amplitude of the resonance frequency component of the wheel speed, and reducing the average braking force acting on the wheel when the amplitude of the resonance frequency component of the wheel speed detected by the detecting means is smaller than a reference value. And a control means for controlling as described above.

The control means of the invention of claim 6 preferably controls so as to increase the average braking force when the amplitude of the resonance frequency component is larger than the reference value.

According to a seventh aspect of the present invention, there is provided excitation means for minutely exciting the braking force acting on the wheel at the resonance frequency of the vibration system constituted by the vehicle body, the wheel and the road surface and in accordance with the amplitude command, and the wheel speed. Detecting means for detecting the amplitude of the resonance frequency component, and obtaining the amplitude command so that the amplitude of the resonance frequency component of the wheel speed detected by the detecting means becomes a reference value, and the amplitude command is larger than the reference amplitude value. The control means for controlling so as to reduce the average braking force that sometimes acts on the wheels.

The control means of the invention of claim 7 may further comprise means for controlling so as to increase the average braking force acting on the wheels when the amplitude command is smaller than the reference amplitude value.

The invention according to claim 8 further comprises an exciting means for minutely exciting the braking force acting on the wheel at the resonance frequency of the vibration system constituted by the vehicle body, the wheel and the road surface, and a detecting means for detecting the wheel speed. Controlling means for reducing the average braking force acting on the wheels when the frequency when the gain of the wheel speed amplitude with respect to the braking force amplitude is maximum is larger than a reference value. It was done.

It is preferable that the exciting means of the invention of claim 8 minutely excite the braking force controlled by the driver at the same frequency as the resonance frequency of the wheel speed when the tire is gripped.

The control means of the invention of claim 8 is a conversion means for converting each of the amplitude of the wheel speed and the amplitude of the braking force into frequency series data, and the braking force for each frequency in the frequency series data. It can be composed of a calculating means for calculating the gain of the amplitude of the wheel speed with respect to the amplitude and an extracting means for extracting the frequency at which the gain is maximum.

Further, it is effective that the control means of the invention of claim 8 is further provided with means for controlling so as to increase the average braking force when the frequency is smaller than the reference value.

First, the principle of the present invention will be described. As shown in FIG. 5, when a vehicle including a vehicle body 12 having a weight W is traveling at a speed v, a vibration phenomenon at wheels, that is, a vibration system of a vibration system constituted by the vehicle body, the wheels, and the road surface, Consider the model shown in FIG. 6, which is equivalently modeled by the wheel rotation axis.

Here, the braking force (braking force) acts on the road surface via the surface of the tread 15 of the tire that is in contact with the road surface, but this braking force actually acts on the vehicle body 12 as a reaction from the road surface. The equivalent model 17 for converting the vehicle body weight into the rotation axis is connected to the side opposite to the wheel 13 via the friction element 16 between the tread of the tire and the road surface. This is similar to the case where a chassis dynamo device can simulate the weight of a vehicle body with a large inertia under a wheel, that is, a mass on the side opposite to the wheel.

Wheel 13 including a tire rim in FIGS. 5 and 6.
The inertia of J _w , the spring element 1 between the rim and the tread 15
4 is K, the inertia of the tread 15 is J _t , the friction coefficient of the friction element 16 between the tread 15 and the road surface is μ, and the inertia of the equivalent model 17 of the weight of the vehicle body 12 in terms of the rotation axis is J.
_{Assuming V} , the characteristics of the entire system are as shown in (2) to (4) below. In the following, the first-order differential d / dt with respect to time
Is represented by "", and the second derivative d ² / dt ² with respect to time is represented by "".

J _W θ _w "= -T + K (θ _t −θ _w ) ... (2) J _t θ _t " = − K (θ _t −θ _w ) + μWR ... (3) J _v ω _v '= -μWR ··· (4) here, _{w w} = θ _w' in the _{··· (5) J v = R} 2 W ··· (6) ω v = v / r ··· (7) Yes, θ _w is the rotation angle of the wheel 13, θ _w "is the rotation angular acceleration of the wheel 13, w _w is the rotation angular velocity of the wheel 13, that is, the wheel speed, θ _t is the rotation angle of the tread 15, and θ _t " is the tread 15 Is the rotational angular acceleration, ω _v is the rotational angular velocity of the vehicle body equivalent model 17 in terms of the rotational axis, T is the braking torque applied to the wheels 13, W is the weight of the vehicle body, and R is the wheel radius. Braking torque T is actually carried out by controlling the pressure P _b of brake valves.

Considering that the tread 15 and the vehicle body equivalent model 17 are directly connected when the tire is gripped, the inertia of the sum of the inertia of the vehicle body equivalent model 17 and the inertia of the tread 15 and the inertia of the wheel 13 are considered. And and the resonance wave number f ₁ of the wheel resonance system at this time is f ₁ = √ {(J _w + J _t + J _v ) K / J _w (J _t + J _v )} / 2π (8) Becomes This state corresponds to the area A1 in FIG.

On the contrary, when the friction coefficient μ of the tire approaches the peak μ, the friction coefficient μ of the tire surface is the slip ratio S.
With respect to the vehicle body equivalent model 17, the component accompanying the vibration of the inertia of the tread 15 does not affect the vehicle body equivalent model 17. That is, the tread 15 and the vehicle body equivalent model 17 are equivalently separated, and the tread 15 and the wheel 13 resonate. The resonance frequency f ₂ of the wheel resonance system at this time is f ₂ = √ {(J _w + J _t ) K / J _w J _t } / 2π (9). This state corresponds to the area A2 in FIG. 2. Generally, when the point of the peak μ is reached, the state is instantly changed to the area A3 and the tire is locked. On the other hand, the gain of the wheel speed at the resonance frequency also sharply decreases immediately before the peak μ.

The magnitude relationship between the inertias is J _t <J _w <J _v (10), and from this, f ₁ <f ₂ (11) That is, when the tire locks, the resonance frequency of the wheel resonance system shifts to the high frequency side. Also,
This change in the resonance frequency occurs rapidly near the peak μ.

The model is simplified and the inertia J of the tread 15 is
Even when ignoring _t , the peak of the resonance frequency of the wheel resonance system and the peak of the wheel speed gain change when approaching the peak μ state, and the same analysis is possible.

By observing the change in the resonance frequency f ₁ or the peak of the wheel speed gain, and keeping the resonance frequency at a value equal to or lower than the peak μ, that is, a value when the tire is gripped, the lock of the tire is prevented. Therefore, by applying the maximum braking force in this range to the wheels, the optimum braking operation can be performed.

Therefore, in the invention of claim 1, the detecting means detects the vibration characteristic of the wheel speed, and the control means causes the peak friction coefficient between the tire and the road surface based on the detected vibration characteristic of the wheel speed. The average braking force acting on the wheels is controlled to reach the value.

The control means for controlling the average braking force acting on the wheels are the braking force operating means by the driver's operation or automatic driving by computer control or the like during normal traveling, and the slip having a friction coefficient of peak μ. And a reduction means for reducing the braking force by the braking force operating means when the ratio is exceeded. Here, at the time of emergency braking, a control means for applying an average braking force so as to maintain the friction coefficient at the peak μ in order to realize the minimum braking distance unrelated to the driver's intention may be used.

The detecting means detects the vibration characteristic of the wheel speed capable of determining the slip state, and
In a vibration system composed of wheels and a road surface, the frequency at which the amplitude value of the wheel speed vibration component is maximum can be regarded as the resonance frequency, so that the frequency components of the braking force acting on the wheel and the wheel speed are By comparing the amplitude gains of the above, the frequency at which the amplitude gain of the wheel speed with respect to the braking force becomes maximum is obtained, and the slip state can be known from this frequency change. Therefore, the resonance frequency itself may be detected from the frequency transfer characteristic.

The peak of the amplitude gain of the wheel speed is
It decreases with the approach to the peak μ. Therefore, if the resonance frequency when the tire is gripping is known, by exciting the braking force at the resonance frequency that occurs between the wheel and the road surface while the tire is gripping, the lock time The braking gain of the resonance frequency component-the amplitude gain of the wheel speed is reduced, and it is possible to determine the approach to the peak μ. That is, if the resonance frequency in the state where the tire is gripping is known, the braking force of this resonance frequency component-the slip state can be determined from the amplitude gain of the wheel speed, so the braking force of the resonance frequency component-
The amplitude gain of the wheel speed may be detected, the amplitude of the resonance frequency component of the wheel speed is detected, and the excitation of the excitation means is adjusted so that the fluctuation of the amplitude becomes a predetermined value. The amplitude gain of the braking force of the resonance frequency component-the wheel speed may be calculated from the amplitude of the excitation.

Therefore, in the first aspect of the invention, it is possible to further provide an exciting means for minutely exciting the braking force acting on the wheel at a predetermined frequency.

Further, in the third aspect of the invention, the resonance frequency is obtained from the frequency distribution of the wheel speed by the resonance frequency detecting means, and the average braking force acting on the wheel when the resonance frequency is higher than the reference value is obtained by the control means. It is controlled to decrease.

According to the invention of claim 4, by the exciting means,
The braking force acting on the wheel is minutely excited at the resonance frequency of the vibration system constituted by the vehicle body, the wheel, and the road surface, and the amplitude of the resonance frequency component of the wheel speed is detected by the detection means. Then, the control means controls to reduce the average braking force acting on the wheel when the gain of the amplitude of the resonance frequency component of the wheel speed with respect to the amplitude of the minute excitation of the braking force is smaller than the reference value.

According to the sixth aspect of the invention, the braking force acting on the wheel is finely excited at the resonance frequency of the vibration system constituted by the vehicle body, the wheel and the road surface and at a constant amplitude, and the amplitude of the resonance frequency component of the wheel speed is changed. The resonance frequency is detected and the resonance frequency is obtained from the frequency distribution of the wheel speed vibration component. Then, the control means controls so as to reduce the average braking force acting on the wheel when the amplitude of the detected resonance frequency component of the wheel speed is smaller than the reference value.

According to the seventh aspect of the invention, the braking force acting on the wheel is minutely excited at the resonance frequency of the vibration system constituted by the vehicle body, the wheel and the road surface and at a constant amplitude, and the amplitude of the resonance frequency component of the wheel speed is changed. The amplitude command of the minute excitation is detected so that the amplitude of the resonance frequency component of the wheel speed detected by the detecting means becomes the reference value, and the average command acting on the wheel when the amplitude command is smaller than the reference value. Control to reduce the braking force.

In the eighth aspect of the invention, the braking force acting on the wheel is minutely excited at the resonance frequency of the vibration system constituted by the vehicle body, the wheel, and the road surface, the wheel speed is detected, and the amplitude of the braking force is detected. When the frequency at which the gain of the wheel speed amplitude becomes maximum is larger than the reference value, the average braking force acting on the wheels is controlled to be reduced.

The amplitude of the resonance frequency component of the wheel speed detected in the fourth aspect of the invention tends to change depending on the vehicle speed or a physical quantity related to the vehicle speed such as the wheel speed.

Therefore, in the fourth aspect of the invention, the vehicle speed or the physical quantity related to the vehicle speed is detected by the physical quantity detecting means, and the detected vehicle speed or the physical quantity related to the vehicle speed is made to depend on the fourth quantity.
It is possible to control the average braking force acting on the wheel to be reduced when the reference value in the invention is changed and the amplitude of the resonance frequency component of the detected wheel speed is smaller than the changed reference value. As a result, the maximum braking force with the tire gripped at each vehicle speed can be realized.

In each of the above inventions, the vehicle speed estimating section is not required and the vehicle acceleration is not used, so that the control device and the sensor can be simplified.

[0056]

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

Antilock brake control device (ABS) for normal running of each embodiment described below
As shown in FIG. 7, the control unit C that controls the vehicle motion system 22 to control the braking force applied to the wheels, and the braking force by the driver operation unit 24 including the brake pedal 34 that is operated by the driver are very small. The detection unit 20 detects the resonance characteristic of the wheel speed when the vibration braking force is applied.

The control section C controls the braking force applied by the driver operating section 24 to give a minute vibration to the braking force exciting section 19.
And a braking force reduction unit 21 that suppresses an increase in braking force based on the resonance characteristic of the wheel speed detected by the detection unit 20.

Further, the detecting section 20 includes a wheel speed sensor for detecting the wheel speed and an amplitude detecting means for detecting the amplitude of the resonance frequency component of the wheel speed, or a wheel speed sensor for detecting the wheel speed and a minute excitation of the braking force. The extraction means may be configured to extract a frequency at which the amplitude gain of the resonance frequency component of the wheel speed with respect to the amplitude becomes maximum. (First Embodiment) Next, the ABS of the first embodiment will be described. As shown in FIG.
Is connected to the wheel speed sensor and the wheel speed sensor for detecting a wheel speed omega _w is constituted by an amplitude value detecting section 23 for detecting an amplitude value of the resonance frequency component of the wheel speed omega _w. This wheel speed sensor is attached to the vehicle motion system 22 to be controlled and outputs an AC signal proportional to the wheel speed ω _w .

Further, the braking force excitation unit 19 of the control unit C
Is the detected value ω from the amplitude value detector 23 _dBased on
Key command P_bIs the amplitude value of the small amplitude of_vCompute
The braking force excitation command computing unit 26
The force reduction unit 21 detects the detected value ω from the amplitude value detection unit 23._d
And a minute break from the minute braking force excitation command calculator 26.
Force excitation amplitude command P_vBrake force reduction command based on
P_rComprising a braking force reduction command calculator 25 that calculates
Have been.

The braking force reduction command calculation unit 25 and the minute braking force excitation command calculation unit 26 include a braking force reduction command P _r from the braking force reduction command calculation unit 25, a braking force P _{d from} the driver operation unit 24, and a minute amount. Minute braking force excitation amplitude command P _v from the braking force excitation command calculation unit 26
Is connected to a brake valve driver 27 that generates a braking force command that is an input to the vehicle motion system 22 that is a control target, and applies the braking force command to the vehicle motion system 22.

The amplitude value detecting section 23, as shown in FIG.
The band pass filter 28 set in a predetermined range including the resonance frequency f ₁ of the wheel speed when the tire grips the tire, the full wave rectifier 29 for rectifying the output of the band pass filter 28, and the full wave rectifier 29 output Is constituted by a low-pass filter 30 for smoothing and converting to DC. The amplitude detection circuit 23, the tire is only detected component of the resonance frequency f ₁ of the wheel speed when on grip, since the component of the resonance frequency f ₁ of the wheel speed and outputs the direct current, the amplitude detection circuit The detected value ω _{d of} 23 is the amplitude value of the resonance frequency f ₁ component of the wheel speed.

By the way, the resonance that occurs between the wheel and the road surface is basically a damped vibration and does not become a continuous vibration. Therefore, when the tire is gripped by the vibration caused by a disturbance such as unevenness of the road surface, the resonance occurs. The detection of the frequency f ₁ component becomes difficult.

Therefore, in the present embodiment, in the minute braking force excitation command calculation unit 26, a minute frequency equal to the resonance frequency f ₁ of the wheel speed when the tire grips the braking force instructed by the driver. A minute amplitude command P _v for applying vibration is calculated, and minute vibration having the same frequency as the resonance frequency f ₁ of the wheel speed when the tire is actively gripping is applied to the braking force commanded by the driver. Thus, the change in the resonance frequency f ₁ is detected from the amplification characteristic.

As shown in FIG. 10, in the frequency characteristic of the wheel resonance system, the peak of the wheel speed gain at the resonance frequency becomes lower as the friction coefficient μ approaches the peak value.
When the friction coefficient μ exceeds the peak value, the resonance frequency shifts to a frequency side higher than the resonance frequency f ₁ when the tire grips. As for the component of the resonance frequency f _{1 when} the tire is gripped, the amplitude of the resonance frequency f ₁ component decreases as the peak μ state is approached. Therefore, the resonance frequency f that appears in the wheel speed
It is possible to detect the approach of the _first gain of the micro vibration component to the peak μ state.

Therefore, in the present embodiment, as shown in FIG. 11, the braking force reduction command calculator 25 for controlling the reduction of the average braking force P _m , which is the average braking force applied to the wheels, is set to the amplitude value. a calculation unit 31 for calculating a micro-excitation gain g _d is the gain of the detected value omega _d for small braking force excitation amplitude command P _v of the detector 23, the difference between the micro-excitation gain g _d and a reference value g _s g _d - g _s , proportional gain G _Pr1
And a PI controller 32 that calculates a reduced braking force by proportional-plus-integral control using the integral gain G _Ir1 and a negative value by removing a positive value so as not to be commanded beyond the braking force P _d by the driver's operation. To reduce braking force command P
It is composed of a positive value removing unit 33 which outputs as _r .

This braking force reduction command calculator 25 is
Small excitation gain g_dIs the reference value g_sIf it's bigger,
Chi minute braking force excitation amplitude command P_vTest when excited by
Outgoing price ω_dIs the reference value g_sP_v(However, ω_dIs the rotational speed
The unit is [rad / s], P_vIs pressure or torque
Is [Pa] or [Nm])
Assuming that the tire grips as described in 0.
And average braking force P _mMaintain the small excitation gain
g_dIs the reference value g_sSmaller, i.e.
Key force excitation amplitude command P_vDetected value when excited by_dBut
Reference value g_sP_vThe smaller the friction coefficient peaks μ
Average braking force P because it is approaching _mDecrease
You.

As shown in FIG. 12, the average braking force P _m
Is P _m = P _d + P _r , P _r ≦ 0 (12), and since the reduction braking force command P _r is always a negative value, it exceeds the braking force P _d by the driver's operation and averages. The braking force P _m is never commanded. By maintaining the average braking force P _m , the braking force that acts on the wheels increases in accordance with the treading force of the driver.

The brake valve driver 27 commands the average braking force P _m and the minute braking force excitation amplitude command P.
_This is the part that converts _v into the braking torque for the actual wheel,
As shown in FIG. 13, the booster 35 and the valve control system 3
6, a brake caliper 37, a reservoir tank 38, and an oil pump 39.

The brake pedal 34 is the brake pedal 3
4 is connected to a pressure increasing valve 40 of a valve control system 36 via a booster 35 that increases the operating force of No. 4. A valve operation command is input to the valve control system 36, and
The pressure reducing valve 4 connected to the brake caliper 37
It is connected to the reservoir tank 38 via 1.

This valve operation command is generated by the circuit shown in FIG. This circuit inputs the average braking force command P _m and the minute braking force excitation amplitude command P _v ,
As shown in FIG. 15, the command of the average braking force P _m is excited at the same excitation frequency as the resonance frequency f ₁ when the tire is gripping.

The operating principle will be described below. First, the calculation unit 18A calculates the sum P _m1 of the command for the average braking force P _{m and} the command for the minute braking force excitation amplitude P _v , and the calculation unit 20A.
Then, a difference P _m2 between the average braking force P _m command and the minute braking force excitation amplitude command P _v is calculated. The sum P _m1 corresponds to the upper limit of the braking force command, and the difference P _m2 corresponds to the lower limit of the braking force command. Using the two sums P _m1 and P _m2 as commands, the calculating units 18B and 20B calculate the differences e1 and e2 from the actual brake pressure P _{b *,} and the command generating units 42 and 43 calculate the differences e1 and e2 from the respective differences e1 and e2. The brake pressure is excited by calculating the position of the valve, generating a command, and switching the both at an excitation frequency that is the same frequency as the resonance frequency f ₁ . However, for the sum P _m1 , a command to increase and hold only,
For the difference P _m2 , commands are generated only for holding and depressurizing. By generating the command in this way, it is possible to prevent excessive vibration of the brake pressure command and perform excitation at the same frequency as the resonance frequency f ₁ .

When increasing the braking hydraulic pressure, the brake valve driver 27 uses the pressure increasing valve 40 on the booster 35 side.
Open and close the pressure reducing valve 41 of the reservoir tank 38 to keep the booster pressure as it is.
Input to 7. On the contrary, when reducing the braking hydraulic pressure, the pressure increasing valve 40 is closed and the pressure reducing valve 41 is opened, so that the pressure in the brake caliper 37 is decreased via the oil pump 39. When both valves are closed, the braking hydraulic pressure is maintained and the braking force is maintained.

In such a valve operation, the pressure in the brake caliper 37 does not rise beyond the braking force by the driver's operation of the pedal 34, and the ABS does not operate during weak braking during normal traveling. When the braking force by the driver's operation of the pedal 34 exceeds the peak μ and the vehicle is about to be braked, the ABS operates and the braking operation following the peak μ can be realized.

According to this ABS, when the friction coefficient reaches the peak μ state when the braking force, which is the sum of the braking force by the driver's operation and the minute vibration braking force, is applied to the wheel, the braking force reduction unit 21 The average braking force is reduced and further braking force increase is suppressed, which prevents the tire from locking.

On the other hand, in the case of an emergency braking operation in the automatic driving system, stable braking operation with a minimum braking distance is required regardless of the driver's intention.
As for the braking force applied to the wheels, the average braking force is increased / decreased so that the peak μ state is achieved regardless of the value by the driver's operation, and the braking operation is performed. Such an emergency braking operation can be applied to a train or the like. This is the same in all the embodiments described below.

FIGS. 16 (1) to 16 (4) show A of the present embodiment.
The operation of each part of the BS is illustrated. (1) is the braking force, (2) is the wheel speed, (3) is the minute excitation gain,
(4) is a friction coefficient. Here, the initial speed of the vehicle is 40
km / h, peak μ value is 0.6, reference micro excitation gain g _s
Is 0.01 rad / s / Nm.

When the braking force excitation is started simultaneously with the driver's operation and the minute excitation gain g _d is equal to or _larger than the reference value g _{s, the} braking force P _d by the driver's operation is applied to the wheel as it is. When the detected minute excitation gain g _d falls below the reference value g _s , the braking force reduction unit 21 reduces the average braking force P _m . As a result, it can be seen that the friction coefficient μ between the tire road surfaces is fixed near the peak without causing the wheels to lock.

This embodiment is basically based on the current ABS.
It is realized by diverting, and can be realized only by changing the valve operation of the brake valve. This facilitates changes from the current ABS system. Further, since it is not necessary to estimate the vehicle body speed, a G sensor or the like for detecting the vehicle body acceleration / deceleration is not required, and the hardware can be simplified. In addition, the frequency of braking force excitation is 40Hz
However, it can be realized without giving discomfort to passengers by setting the excitation amplitude to a sufficiently small level.

(Second Embodiment) Next, a second embodiment will be described. In this embodiment, the present invention is applied when the amplitude of the input minute braking force can be maintained in a constant state. As shown in FIG. 17, a constant minute braking force excitation amplitude command P _v is applied. A braking force reduction command computing unit that computes the braking force reduction command P _r from only the output minute braking force excitation command computing unit 44 and the detection value ω _d of the amplitude value detection unit 23 that is the amplitude of the resonance frequency component of the wheel speed vibration. 45 and. It should be noted that the frequency of the micro-excitation in the present embodiment is the resonance frequency of the wheel resonance system as in the first embodiment.

[0081] The braking force reduction command calculating unit 45, as shown in FIG. 18, the detected value of the amplitude detection circuit 23, i.e. the difference between omega _s of the amplitude omega _d and the reference value omega _s of the resonance frequency component -
A PI controller 46 that performs proportional- _plus- integral control using a computing unit that computes ω _d and a proportional gain G _pr2 and an integral gain G _Ir2.
And a positive value removing unit 47 that removes a positive value so as not to be commanded by exceeding the brake pressure P _d by the driver's operation.

In the present embodiment, the output of the amplitude value detector 23 is
Force or amplitude of resonance frequency component ω _dIs the reference value ω_sThan
If it is large, it means that the tire is gripping, and the average
Braking force P_mBrake force reduction command P to maintain_r
, And conversely, the amplitude of the resonance frequency component ω_dIs the reference value ω_s
If it gets smaller, it is approaching the locked state
Brake force reduction command P_rTo reduce the average braking force
Reduce.

This embodiment is also basically realized by diverting the existing ABS, and can be realized only by changing the operation of the brake valve. In the present embodiment, it is not necessary to calculate the gain of the amplitude of the resonance frequency component of the wheel speed with respect to the amplitude of the braking force due to the minute excitation, so the ABS can be simplified.

(Third Embodiment) Next, a third embodiment will be described.
The state will be described. In this embodiment, the average braking force is
Applies to the wheel speed by controlling the minute braking force applied to
It is designed to keep the amplitude of minute vibrations constant.
As shown in 19, the amplitude of the resonance frequency component of the wheel speed
Detection value ω of certain amplitude value detection unit 23_dFrom minute braking force
Excitation amplitude command P_vMicro brake force excitation command output to output
Calculation unit 48 and minute braking force excitation amplitude command P _vFrom blur
Key reduction command P_rBrake force reduction command calculation
And a section 49.

As shown in FIG. 20, the braking force excitation command calculation unit 48 outputs the output of the amplitude value detection unit 23, that is, the difference ω _s −ω between the amplitude ω _d of the resonance frequency component and the reference value ω _s.
It is composed of a computing unit that computes _d and a PI controller 50 that performs proportional-plus-integral control with a proportional gain G _Pv and an integral gain G _Iv .

Further, the braking force reduction command calculation unit 49
As shown in FIG. 21, a calculator for calculating a difference P _s −P _v between the minute braking force reference amplitude value P _s and the minute braking force excitation amplitude command P _v , a proportional gain G _Pr3 and an integral gain G
A PI controller 51 for performing proportional-integral control by _Ir3, is composed of a positive removal unit 52 for removing positive value so as not commanded by exceeding the braking pressure P _d by the driver operation.

In the present embodiment, the small braking force excitation amplitude command P _v is generated by feeding back the difference ω _s −ω _d between the amplitude ω _d of the resonance frequency component of the wheel speed and the reference value ω _s . That is, when the amplitude ω _d is smaller than the reference value ω _s , the minute brake excitation amplitude command P _v is increased, and conversely, when the amplitude ω _d is larger than the reference value ω _s , the minute braking force excitation amplitude command P _{v is generated.} By reducing the value, the amplitude value ω _d of the excitation frequency component that appears in the wheel speed is controlled to a minute constant reference value ω _s . By controlling in this way, it is possible to perform excitation within a range that the vehicle driver cannot feel.

As described above, in this embodiment, since the minute braking force excitation amplitude command P _v is controlled so that the amplitude ω _{d of the} minute vibration appearing at the wheel speed is constant, the peak μ
The deviation of the resonance point due to the approach to the position appears as an increase in the excitation amplitude command P _v of the braking force that is the input.

Therefore, the deviation from the constant small braking force reference amplitude value P _s is fed back, and the excitation amplitude command P _v of the braking force is changed to the minute braking force reference amplitude value P _s.
Reduces the mean braking force P _m when larger, by controlling such that excitation amplitude command P _v of the braking force is increased the mean braking force P _m upon the smaller micro braking force reference amplitude value P _s Conversely, peak Brake operation is performed following μ.

This embodiment is basically realized by diverting the existing ABS, and can be realized only by changing the valve operating method of the brake valve. Again,
It is not necessary to calculate the gain for the amplitude of the braking force for the amplitude of the wheel speed due to the minute excitation, and the control device can be simplified. In addition, by setting the minute vibration appearing in the wheel speed to a sufficiently small value, it is possible to always excite in a range where the driver does not sense it and prevent uncomfortable vibration.

(Fourth Embodiment) In each of the above embodiments, the resonance characteristic is obtained by the change in the amplitude of the resonance frequency f ₁ component of the wheel speed during tire grip, but the fourth embodiment The resonance frequency itself is observed from the frequency transfer characteristics, and the average braking force is controlled by changing the resonance frequency itself.

[0092] The present embodiment, as shown in FIG. 22, a small braking force excitation command calculating unit 53 for calculating a micro-braking force excitation amplitude command P _v, the braking force P from the braking force P _b and the wheel speed omega _w A slipping state determination unit 55 that calculates a resonance frequency f _d when the gain of the amplitude of the wheel speed ω _w with respect to the amplitude of _b becomes maximum, and a braking force reduction command P _r from the frequency f _d when the gain becomes maximum. And a braking force reduction command calculation unit 54 for calculating.

The slipping state judging section 55 is as shown in FIG.
And the wheel speed ω_wAnd braking force P _bFor a fixed time interval
FFT processing unit 56 for performing fast Fourier transform on data, and
Braking force P for each frequency of the obtained frequency series data_b
Wheel speed ω_wComputing unit 57 for computing the gain of
And the frequency transfer characteristic is obtained, and the frequency f with the maximum gain is obtained.
_dAnd an extraction unit 58 for extracting

Using this slipping state judging section 55, the command of the average braking force P _m is given by the resonance frequency f _d as the reference value f _s.
A braking operation that follows the peak μ can be performed by calculating a command to increase the frequency when the gain is smaller and decrease the frequency when the maximum gain f _d is greater than the reference value f _s .

The braking force reduction command calculation unit 54 is shown in FIG.
As described above, a calculator for calculating the difference f _s −f _d between the maximum gain frequency f _d and the reference value f _s, and a PI controller 59 for performing proportional and integral control by the proportional gain G _Pr4 and the integral gain G _Ir4. , A positive value removing unit 60 that removes a positive value so as not to be instructed by exceeding the brake pressure P _d by the driver's operation.

Also in this embodiment, the amplitude change of the resonance frequency component is detected by processing the wheel speed signal, and it can be realized without adding a sensor or the like.

[0097] (Fifth Embodiment) A fifth embodiment, the amplitude of the resonance frequency f ₁ of the wheel speed seeking the correlation between a single sine wave of the resonance frequency f ₁ of the wheel speed and the wheel speed It is detected, and can be configured by a neural computer.

FIG. 25 shows a circuit for detecting the amplitude component of a desired resonance frequency f ₁ by the correlation with a single sine wave. The delay time is delayed by holding necessary time series data for a fixed time ΔT. A circuit 61, a product-sum calculation unit 62 that multiplies and adds each time value of a cosine wave having a period of this constant time ΔT to calculate a product sum R, and a product-sum calculation unit 62 that multiplies each time value of a sine wave and add. The sum of products operation unit 63 calculates the sum of products I, and the calculation unit 64 calculates the sum of products R and the square root of the sum of squares of the sum of products I.

When the sampling interval of the wheel speed ω _w is 1 ms and the frequency to be detected is 40 Hz, one cycle of the component to be detected is 25 sample points. Sum of products R and sum of products I are And the coefficients c _i and s _i are c _i = cos {2π (i−1) / 25} (15) s _i = sin {2π (i−1) / 25} (i = 1, 2 ,. .25) (16), the product sum R and the product sum I have a frequency of 1 / ΔT.
It is nothing but the calculation of the real and imaginary parts of the Fourier coefficient for the component. Therefore, the sum of products R and the sum of products I
If the square root of the sum of squares of is calculated, its amplitude value can be obtained.

Also in this embodiment, the amplitude change of the resonance frequency component is detected by processing the wheel speed signal, and it can be realized without adding a sensor or the like.

(Sixth Embodiment) FIG. 26 is a block diagram of a sixth embodiment in which a braking force exciting portion is constituted by a piezoelectric element. In the present embodiment, the average braking force applied to the tire 65 is controlled by the pressure control in the brake caliper 66, and at the same time, the minute excitation voltage is applied to the piezoelectric element 68 arranged on the contact surface with the brake disc 67. , The braking force is excited.

The minute braking force excitation command calculators 26, 44, 53 and the braking force reduction command calculators 25, 45, 49, 54 of the above-mentioned respective embodiments have a higher control system than the above-mentioned structure. For example, it may be configured by using a robust control system such as H ∞ control or 2 degrees of freedom control, a neural computer, a fuzzy control system, or adaptive control.

Also in this case, the processing is performed based on the wheel speed from the wheel speed sensor, and no new hardware is required. The control algorithm can be changed by changing the program in the computer used for control, and a more optimal control system can be easily used.

Further, in each of the above embodiments, the pressure control system is constructed by feeding back the actual braking force _{Pb *} , but the control system is constructed without feeding back the actual braking force by program control or the like. It is also possible.

Further, when the driving / braking torque can be controlled by electricity as in an electric vehicle, it is possible to excite by adding a minute vibration to the driving current.

In this embodiment, the ABS device can be easily realized by adding a minute excitation amplitude to the command of the current control system of the electric vehicle, and a new sensor is not required for detecting the rotation speed of the electric motor. . An instantaneous speed observer or the like can be used for the method of detecting the rotation speed of the electric motor, and a more accurate control system configuration is also possible.

Conventionally, in order to derive the approximate value of the vehicle speed, it is necessary to extremely reduce the braking force during braking, which also causes an uncomfortable vibration at the wheel at a relatively low frequency. However, in each of the above-mentioned embodiments, since it is based on the physical phenomenon of the wheel resonance system, an absolute vehicle speed is not required and uncomfortable braking can be eliminated.

Further, by making the excitation to the braking force minute, it is possible to fix the friction coefficient μ in the vicinity of the peak value, which is larger than the conventional one that requires a relatively large amplitude variation. The braking distance becomes shorter.

Further, when the road surface condition changes, the resonance frequency also changes, and in that case, stable operation can be performed. This makes it possible to significantly reduce the tuning process required for manufacturing the ABS device.

Further, the sensor signal required for processing is basically only the wheel speed, and can be constructed by using a relatively inexpensive sensor such as a rotary encoder.

(Seventh Embodiment) In each of the above-described embodiments, an example in which the tire resonance characteristic is detected by using the braking force excitation has been described. However, the tire resonance characteristic is not detected by using the braking force excitation. But it is possible. That is, the resonance frequency can be detected from the frequency distribution of the wheel speed change during traveling.

For example, the resonance frequency of the tire resonance system can be regarded as the resonance frequency when the wheel speed vibration component is large and the amplitude value is the maximum frequency. An embodiment in which this excitation means is not used is shown in FIG.

In this case, the configuration of the slipping state determining section 70 is as follows.
As shown in FIG. 28, the frequency series data is calculated from the time series data of the wheel speed ω _w by the FFT processing by the FFT processing unit 71, and the extraction unit 72 extracts the frequency with the maximum gain as the resonance frequency.

Using this slipping state judging section 70, the average blur
Key pressure command P_mIs the resonance frequency f _dIs the reference value f_sThan
If it is small, increase it to increase the resonance frequency f_dIs the reference value f_sThan
If you calculate the command to decrease it if it is large, peak
The braking operation follows μ.

Further, the brake pressure reduction command calculation unit 69
29 is a feedback control system in which the difference f _s −f _d of the resonance frequency detection value f _d with respect to the reference value f _s is input to the PI controller 73 of the proportional gain G _Pr5 and the integral gain G _Ir5 as shown in FIG. Can be configured. Also in this embodiment, only the negative value is adopted by the positive value removal circuit 74 so that the command does not exceed the brake pressure P _d by the driver's operation.

Further, in the present embodiment, the frequency at which the amplitude value reaches the peak value is used as the resonance frequency, but it is also possible to apply the resonance characteristic from the outline of the amplitude-frequency characteristic itself to obtain the resonance frequency.

Also in this embodiment, the amplitude change of the resonance frequency component is detected by processing the vehicle speed signal.
It can be realized without adding a sensor or the like to the conventional ABS.

Further, since it is not necessary to excite the brake,
The actuator for excitation can be omitted.

(Eighth Embodiment) The tire does not lock.
Wheel speed at the resonance frequency in the open state-excited brake pressure gauge
Memorize the in, and use the relative decrease
Control system to determine whether the tires are close to lock.
FIG. 30 shows the eighth embodiment thus constructed. This embodiment
Then, the brake pressure reduction command calculator 75 is shown in FIG.
As described above, the wheel speed-excitation brake pressure gain calculation unit 77
Output value g_dAbout the average brake pressure P _mIs small enough
The value at the time of opening is stored in the memory 76, and the stored value
g_s2Relative gain reduction from g_s2-G_dReference value of
g_s1Difference from_s1-(G_s2-G_d) For proportional gain
G_pr6 , Integral gain G_Ir6 Via the PI controller 78 of
Reduced brake pressure is calculated and the brake pressure is
Power P_dTo the positive value removal circuit 79 so as not to be commanded beyond
Adopt only the more negative value P_rAnd

The above-mentioned reference value g _s1 becomes an appropriate value according to the change of the wheels and the like (wheel replacement, etc.), so that the locking of the tire can be prevented more effectively.

In the present embodiment, the control system is constituted by the wheel speed-excited brake pressure gain, but as described above, when the minute amplitude due to the excitation of the brake pressure is constant, only the wheel speed minute amplitude is obtained. On the contrary, when the brake pressure is excited so that the small wheel speed amplitude becomes constant, it is possible to judge whether the tire is close to the lock only from the small brake pressure amplitude and calculate the command value. it can.

This embodiment is also realized by diverting the existing ABS control device, and can be realized only by changing the operation method of the brake valve. This facilitates changes from the current system. Further, since it is not necessary to estimate the vehicle body speed, a G sensor or the like for detecting the vehicle body acceleration / deceleration is not required, and the hardware is simplified. Further, the frequency of the brake pressure excitation is about several tens of Hz, and it can be realized without giving a passenger an uncomfortable feeling by setting the excitation amplitude to a sufficiently small level.

(Ninth Embodiment) In the ABS control device of the first embodiment, it is assumed that the minute excitation gain g _{d at} which the friction coefficient μ reaches a peak is constant regardless of the wheel speed, and detection is performed. When the generated minute excitation gain g _d is smaller than the reference value g _s , the braking force is controlled to be reduced,
By fixing it around the peak μ, the maximum braking force is achieved when the tire grips.

However, it has been experimentally known that the minute excitation gain g _d in the state of the peak μ increases as the vehicle speed decreases. Therefore, in the ninth embodiment, by changing the reference value g _s depending on the wheel speed that is one of the physical quantities related to the vehicle speed, the minute excitation gain g _d and the reference value that change according to the vehicle speed are changed. The brake control based on the difference from g _s is optimized.

FIG. 32 shows the constituent blocks of this embodiment. The same constituents as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 32, the difference from the first embodiment is that the wheel speed ω _w is input to the braking force reduction command calculator 25.

As shown in FIG. 33, the braking force reduction command calculation unit 25 calculates an optimum reference value based on the input wheel speed ω _w, and outputs it as a command gain g _s. It is configured to further include a section 80. This command gain calculator 80 has a command gain g _s.
The internal memory stores a table indicating how to change the wheel speed according to the wheel speed ω _w .

The detailed relationship between the wheel speed ω _w and the command gain g _s in this table is as shown in FIG. 34. When the wheel speed ω _w is high, the command gain g _s is small, and as the wheel speed ω _w decreases, the command gain g _s decreases. It is set so that g _s becomes large, that is, the command gain g _s monotonically decreases according to the wheel speed ω _w . This corresponds to the minute excitation gain g _d that increases as the wheel speed ω _w decreases.

The command gain calculating section 80 determines the wheel speed ω.
_{When w} is input, the command gain g corresponding to the input wheel speed ω _w is referred to with reference to the table showing the relationship in FIG.
_Find the value of _s and output it. Therefore, as the input wheel speed ω _w becomes smaller, the command gain g _s having a larger value is output.

The calculator 31 calculates the minute excitation gain g _d , and as described above, the minute excitation gain g _d also changes to a large value as the wheel speed ω _w decreases.

Next, the difference g _d -g _s between the minute excitation gain g _d calculated by the calculation unit 31 and the command gain g _s calculated by the command gain calculation unit 80 is the PI controller 32.
And the reduced braking force is calculated based on this difference. The positive value removing unit 33 removes the positive value from the calculated reduced braking force and outputs it as the reduced braking force command P _r .

In the control based on the reduced braking force command P _r , if the minute excitation gain g _d is larger than the command gain g _s, it is assumed that the tire is gripping, the average braking force P _m is maintained, and conversely the minute excitation force P _m is maintained. If the gain g _d becomes smaller than the command gain g _{s, the} average braking force P _m is decreased because the friction coefficient is approaching the peak μ. At this time, the minute excitation gain g _d changes with the change of the wheel speed ω _w , but since the command gain g _s is also changed so as to cancel this change, the optimum braking force that maintains the peak μ at each speed. Can be controlled.

As described above, by varying the command gain g _s depending on the wheel speed ω _w , it is possible to realize the maximum braking force with the tire gripped at each vehicle speed, and to reduce the stop distance and stop time. It can be shortened.

In the present embodiment, the command gain g _s is changed depending on the wheel speed ω _w , but it may be changed depending on the vehicle speed or a physical quantity related to the vehicle speed other than the wheel speed ω _w. Is also good.

[0135]

As described above, according to the inventions of claims 1 to 8, the antilock braking operation is performed by detecting the change in the vibration characteristics of the wheel speed without estimating the vehicle speed. It is possible to obtain an effect that it is possible to prevent the tire from locking and perform a stable anti-lock braking operation while keeping the resonance frequency of the wheel resonance system at the value when the tire is gripped.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a vehicle body speed estimation method used in a conventional antilock brake control device.

FIG. 2 is a diagram showing a characteristic of a friction coefficient μ between a tire and a road surface with respect to a slip ratio S.

FIG. 3 is a block diagram of an ABS control device using a conventional vehicle body speed estimation unit.

FIG. 4 is a block diagram of a peak μ tracking ABS control device of the present invention.

FIG. 5 is a diagram showing a dynamic model of a vehicle.

FIG. 6 is a diagram showing a model in which a dynamic model of a vehicle is converted into a rotation axis.

FIG. 7 is a conceptual diagram of the peak μ tracking ABS control system of the present invention during normal running.

FIG. 8 is a block diagram of a peak μ tracking ABS control device according to the first embodiment of the present invention.

FIG. 9 is a block diagram illustrating a configuration example of a slipping state determination unit.

FIG. 10 is a diagram showing an increase in the resonance frequency and a decrease in the gain of the resonance frequency component at the time of tire grip.

FIG. 11 is a block diagram illustrating a configuration example of a braking force reduction command calculation unit.

FIG. 12 is a diagram showing an outline of a braking force applied to a wheel.

FIG. 13 is a block diagram showing a hardware configuration of a brake unit.

FIG. 14 is a block diagram showing a configuration of a valve command generation unit.

FIG. 15 is a diagram showing an excitation waveform of a braking force applied to a wheel.

16 (1) to (4) are diagrams showing the operation of each part of the control system of the first embodiment.

FIG. 17 is a functional block diagram of a peak μ tracking ABS control device according to a second embodiment of the present invention.

FIG. 18 is a block diagram showing a configuration example of a braking force reduction command calculation unit.

FIG. 19 is a block diagram of a peak μ tracking ABS control device according to a third embodiment of the present invention.

FIG. 20 is a block diagram showing a configuration example of a minute braking force excitation command calculation unit.

FIG. 21 is a block diagram showing a configuration example of a braking force reduction command calculation unit.

FIG. 22 is a block diagram of a peak μ tracking ABS control device according to a fourth embodiment of the present invention.

FIG. 23 is a block diagram showing a configuration example of a slipping state determination unit.

FIG. 24 is a block diagram showing a configuration example of a braking force reduction command calculation unit.

FIG. 25 is a block diagram illustrating a configuration example of a slipping state determination unit.

FIG. 26 is a block diagram showing a configuration example of a braking force excitation unit by a piezoelectric element.

FIG. 27 is a block diagram of a peak μ tracking ABS control device according to a seventh embodiment of the present invention.

FIG. 28 is a diagram showing a configuration example of a slipping state determination unit of the above embodiment.

FIG. 29 is a diagram showing a configuration example of a brake pressure reduction command calculation unit in the above embodiment.

FIG. 30 is a block diagram of a peak μ tracking ABS control device according to an eighth embodiment of the present invention.

FIG. 31 is a diagram showing a configuration example of a brake pressure reduction command calculation unit in the above embodiment.

FIG. 32 is a block diagram of a peak μ tracking ABS control device according to a ninth embodiment of the present invention.

FIG. 33 is a block diagram illustrating a configuration example of a braking force reduction command calculation unit.

FIG. 34 is a diagram showing a relationship in which the command gain g _s is changed according to the wheel speed ω _w .

[Explanation of symbols]

 22 Vehicle Motion System 23 Amplitude Value Detection Section 24 Driver Scanning Section 25 Brake Force Reduction Command Section 26 Micro-Brake Force Excitation Designating Calculation Section 27 Brake Valve Driver

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Yamaguchi Inventor Hiroyuki Nagakute, Aichi-gun, Aichi Prefecture, Nagatogi 1 1 at 41 Yokomichi Toyota Central Research Institute Co., Ltd. (72) Inventor, Koji Umeno Nagakute, Aichi-gun, Nagachite 41, Yokoshiro Road Inside Toyota Central Research Institute Co., Ltd.

Claims (8)

[Claims] 1. A detecting means for detecting a vibration characteristic of a wheel speed, and a friction coefficient between a tire and a road surface based on the detected vibration characteristic so that a slip ratio is equal to or less than a slip ratio at which a substantially peak value is obtained. An anti-lock brake control device including: a control unit that controls an average braking force applied to wheels. 2. The antilock brake control device according to claim 1, further comprising an excitation means for minutely exciting the braking force acting on the wheel at a predetermined frequency. 3. A resonance frequency detecting means for obtaining a resonance frequency from a frequency distribution of wheel speeds, and a control means for controlling so as to reduce an average braking force acting on the wheels when the resonance frequency is higher than a reference value. Antilock brake control device including. 4. Excitation means for minutely exciting a braking force acting on a wheel at a resonance frequency of a vibration system constituted by a vehicle body, wheels and a road surface, and detection means for detecting an amplitude of the resonance frequency component of wheel speed. Control means for reducing the average braking force acting on the wheel when the gain of the amplitude of the resonance frequency component of the wheel speed with respect to the amplitude of the minute excitation of the braking force is smaller than a reference value. Lock brake control device. 5. A physical quantity detecting means for detecting a vehicle speed or a physical quantity related to the vehicle speed is further included, and the reference value is changed depending on the vehicle speed detected by the physical quantity detecting means or the physical quantity related to the vehicle speed. 4 anti-lock brake control device. 6. Exciting means for minutely exciting a braking force acting on a wheel at a resonance frequency and a constant amplitude of a vibration system constituted by a vehicle body, wheels, and a road surface, and detecting the amplitude of the resonance frequency component of the wheel speed. And a control means for controlling so as to reduce the average braking force acting on the wheel when the amplitude of the resonance frequency component of the wheel speed detected by the detecting means is smaller than a reference value. Anti-lock brake control device. 7. Exciting means for minutely exciting a braking force acting on a wheel at a resonance frequency of a vibration system composed of a vehicle body, wheels, and a road surface and in accordance with an amplitude command, and an amplitude of the resonance frequency component of wheel speed. Detecting means for detecting, and obtaining the amplitude command so that the amplitude of the resonance frequency component of the wheel speed detected by the detecting means becomes a reference value, and acting on the wheel when the amplitude command is larger than the reference amplitude value. An antilock brake control device including: a control unit having a control unit configured to control so as to reduce an average braking force. 8. Excitation means for minutely exciting a braking force acting on a wheel at a resonance frequency of a vibration system constituted by a vehicle body, wheels, and a road surface, a detection means for detecting a wheel speed, and a wheel with respect to an amplitude of the braking force. An antilock brake control device including: a control unit that controls so as to reduce an average braking force that acts on a wheel when the frequency when the gain of the speed amplitude becomes maximum is larger than a reference value.