JPH1148937A - Antilock brake controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the responsiveness of brake pressure in antilock brake control. SOLUTION: This antilock brake controller is constituted of a controlling part 20 which computes an input command in order to bring a difference between a minute gain Gd representing vibrational characteristics of a vehicle speed and a standard gain Gs into 0(zero); a command converting part 21 which outputs a brake pressure minute excitation command for the resonance frequency and which converts the input command into a command for controlling the pressure increasing/decreasing time; an ABS actuator 22 which regulates the brake pressure by adjusting the pressure increasing/decreasing time according to these commands; a mean brake pressure estimating part 23 which estimates actual mean brake pressure; a compensator 24 which computes a compensating command corresponding to a difference between the estimated mean brake pressure and the brake pressure corresponding to the input command; and an adder 26 which adds the compensating command and the input command. Since the compensating command computed by the compensator 24 according to the actual mean brake pressure is added to the input command so as to be inputted into the command converting part 21, the responsiveness of the mean brake pressure to the command signal can be enhanced.

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 for performing an antilock brake operation based on vibration characteristics appearing in wheel speeds, and more particularly to a brake pressure corresponding to an input command and an actual brake pressure. The present invention relates to an anti-lock brake control device in which the response to the brake pressure is enhanced by compensating the input command so as to reduce the difference between the brake command and the input command.

[0002]

2. Description of the Related Art Conventionally, when a brake pressure is slightly excited at a resonance frequency of a wheel resonance system composed of a vehicle body, wheels and a road surface, a peak μ is determined based on a change in vibration characteristics of the wheel resonance system which appears in wheel speed. An anti-lock brake control device (hereinafter, referred to as an "ABS device") that determines a state immediately before and controls a braking force applied to wheels according to a result of the determination.
Has been proposed (Japanese Patent Application No. 7-220920).

In one application of this ABS device, a ratio (small gain) between a brake pressure minute amplitude at a resonance frequency and a wheel speed minute amplitude is calculated, and when the minute gain becomes equal to or less than a reference value, a peak is calculated. Assuming that the state is just before μ, a command to reduce the brake pressure (wheel cylinder pressure) is immediately output to the ABS actuator (control valve). As a result, the braking force is reduced, and the tire lock caused by braking beyond the peak μ is prevented.

On the other hand, when the minute gain exceeds the reference value, a brake pressure increase command is output to the ABS actuator in order to obtain the maximum braking force within a range not exceeding the peak μ. Thereby, the braking force increases and approaches the vicinity of the peak μ, so that the most effective braking can be realized.

According to this prior art, the brake control is performed based on the vibration characteristics of the wheel resonance system which sensitively reflects the slip state between the wheels and the road surface. Regardless, there is an excellent effect that stable and accurate anti-lock brake operation can be performed.

[0006]

However, the above-mentioned prior art has the following problems.

That is, when a brake pressure increasing / decreasing command as shown in FIG. 3A is given to the ABS actuator, a change in the brake pressure by the ABS actuator which operates in response to the command is shown in FIG. As shown in b), there is no immediate response to the pressure increase / low pressure command signal, and a response delay always occurs.

As shown in FIGS. 3A and 3B,
For example, immediately after issuing the pressure increase command, the brake pressure takes a value near the brake pressure at the time of low pressure, and thereafter gradually increases. On the other hand, immediately after issuing the low pressure command, the brake pressure still holds a value near the hydraulic pressure at the time of pressure increase, and thereafter gradually decreases. Note that a minute excitation component due to the excitation of the brake pressure is superimposed on the change curve of the brake pressure in FIG.

As described above, in the above prior art, since there is a response delay of the brake pressure with respect to the command, it is preferable to perform the antilock brake control in consideration of the response delay.

The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide an anti-lock brake control device having improved responsiveness of a brake pressure to a command.

[0011]

In order to achieve the above object, a first aspect of the present invention provides a control valve for controlling an average brake pressure according to an input command, and a micro-excitation for micro-excitation of a brake pressure at a predetermined frequency. Means, first detection means for detecting a vibration characteristic of the wheel speed when the brake pressure is minutely excited by the minute excitation means, and a vibration characteristic of the wheel speed detected by the first detection means. A control means for calculating an input command to the control valve such that a coefficient of friction between a wheel and a road surface has a slip rate equal to or less than a slip rate at which a peak value is substantially attained. A second detecting means for detecting an actual average brake pressure as a response of the control valve to the input command calculated by the control means; Compensating means for calculating a compensation command for reducing the difference between the average brake pressure and the actual average brake pressure detected by the second detecting means, and compensating the input command with the compensation command. It is characterized by the following.

According to the first aspect of the present invention, the first detecting means includes:
The vibration characteristic of the wheel speed when the brake pressure is micro-excited at a predetermined frequency by the micro-excitation means is detected. And
The control means calculates an input command to the control valve such that the friction coefficient between the wheel and the road surface is equal to or less than the slip ratio at which the friction coefficient between the wheel and the road surface becomes a substantially peak value, based on the detected vibration characteristics of the wheel speed. . Then, the control valve controls the average brake pressure according to the input command. Here, the average brake pressure refers to a brake pressure obtained by averaging the minute excitation components of the brake pressure by the minute excitation means.

Next, the principle by which antilock brake control can be performed based on the wheel vibration characteristics as described above will be described.

The vibration phenomenon at the wheels when a vehicle having a vehicle body having a weight W _v is traveling at the speed ω _u , that is, the vibration phenomenon of the vibration system composed of the vehicle body, the wheels, and the road surface, Let us consider with reference to the model shown in FIG.

Here, the braking force (braking force) acts on the road surface via the surface of the tread 15 of the tire in contact with the road surface. However, since this braking force actually acts on the vehicle body as a reaction from the road surface, An equivalent model 17 in terms of the rotation axis of the vehicle body weight is connected to the opposite side of the wheel 13 via a friction element 16 (road surface μ) between the tread of the tire and the road surface. This is the same as the large inertia under the wheels, that is, the weight W _v of the vehicle body can be simulated by the mass on the opposite side of the wheels as in the chassis dynamo device.

In FIG. 5, the inertia of the wheel 13 including the tire rim is J _w , the spring constant of the spring element 14 between the rim and the tread 15 is K, the wheel radius is R, the inertia of the tread 15 is J _t , and the tread 15 and the friction coefficient of the frictional element 16 between the road surface mu, when the inertia of the equivalent model 17 of the vehicle body weight of the rotary shaft conversion and J _V, from the torque T _b 'caused by the wheel cylinder pressure to the wheel speed omega _w The transfer characteristics are

[0017]

(Equation 1)

## EQU1 ## In the transfer characteristic of equation (1), the resonance frequency ω∞ when the tire is gripping the road surface is

[0019]

(Equation 2)

## EQU1 ## When the frictional state between the tire and the road surface approaches the peak μ, the separability between the tire and the road surface increases, and the resonance frequency shifts to the higher frequency side. That is, the slip state immediately before the peak μ can be determined based on the change in the resonance frequency.

Therefore, when this principle is applied to the present invention, as a preferred example, the predetermined frequency of the minute excitation by the minute excitation means is adjusted to the resonance of the vibration system (during tire grip) composed of the wheels, the vehicle body and the road surface. The frequency (ω∞ in the equation (2)) is used, and the vibration characteristic of the wheel speed detected by the detecting means is defined as the ratio of the minute amplitude of the wheel speed at the resonance frequency ω∞ to the minute amplitude of the brake pressure (small gain G _d ). can do. Incidentally, the small gain, the vibration component of the resonance frequency ω∞ ratio of the wheel speed omega _w relative to the brake pressure _{P b (ω w / P b} ) | be expressed as _{((ω w / P b)} s = jω∞) Can also.

The small gain G _d has a characteristic that when the coefficient of friction between the wheel and the road surface approaches the peak μ, the resonance frequency shifts to a higher frequency side and thus sharply decreases. Based on this, the state immediately before the peak μ can be determined very accurately.

When the calculated input command is input to the control valve without any compensation, the actual brake pressure by the control valve as a response to the input command is usually, as shown in FIG. Delay for command.

However, according to the present invention, the compensating means sets the compensation command for reducing the difference between the average brake pressure corresponding to the calculated input command and the actual average brake pressure detected by the second detecting means. The calculation is performed, and the input command to the control valve is compensated by the compensation command (see FIG. 3C). Thereby, the actual brake pressure by the control valve is the brake pressure corresponding to the input command before compensation, that is,
The brake pressure is such that the friction coefficient has a slip ratio equal to or less than the slip ratio at which the friction coefficient substantially reaches the peak value, and is more accurately realized (see FIG. 3B).

Further, the second detecting means of the present invention can be a pressure sensor for directly detecting the wheel cylinder pressure. However, when a minute gain is used as the vibration characteristic of the wheel speed as described above, it will be described later. On the basis of a model in which the gradient of the braking torque with respect to the slip speed (hereinafter, referred to as “braking torque gradient”) is proportional to the small gain,
It can also be realized as a means for estimating the average brake pressure from the input wheel speed and minute gain.

When the control valve has a pressure increasing valve for increasing the brake pressure and a pressure reducing valve for reducing the brake pressure, the micro-exciting means of the present invention is provided as follows. It can be realized by the control method of the control valve.

That is, a first state including a state in which the brake pressure is increased by the pressure increasing valve and a state in which the brake pressure is maintained, and a state in which the brake pressure is reduced by the pressure reducing valve and a state in which the brake pressure is maintained. By controlling the control valve so that the second state is alternately switched with a constant cycle, a minute excitation component having a constant cycle around the average brake pressure can be applied. In order to control the average brake pressure with this control valve, it is sufficient to control the ratio of the length of time of the pressure increasing state to the length of time of the pressure reducing state of the control valve.

[0028]

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

FIG. 1 shows a configuration of an ABS device according to the present embodiment. As shown in the figure, the ABS device has a difference ΔG (= G _d −G) between the minute gain G _d and the reference gain G _s.
s ), a control unit 20 for calculating an input command V _fd for matching or substantially matching ΔG to 0,
A command conversion unit 21 that converts the input command V _fd into a control command of pressure increase / decrease time as an actual command and outputs the command, and outputs a brake pressure minute excitation command at a resonance frequency ω∞; An ABS actuator 22 that adjusts the pressure increase / decrease time of the wheel cylinder pressure according to the control command and applies a small excitation to the wheel cylinder pressure according to the small excitation command, and detects an average brake pressure controlled by the ABS actuator. Average brake pressure detector 23
And

Here, the input command V _fd according to the present embodiment is
Is calculated as a command (P _bc / P _d ) obtained by normalizing the average brake pressure P _bc as the control command with the master cylinder pressure P _d . As described later, the ABS actuator 2
At 2, the commanded average brake pressure P is adjusted by adjusting the ratio of the wheel cylinder pressure increase time to the wheel cylinder pressure increase time.
_bc , the input to the command conversion unit 21 is (P _bc / P
_{By d} ), the pressure increase / decrease time, which changes according to the master cylinder pressure, is immediately responded.

Further, in the present embodiment, the detected average brake pressure Pb is _replaced by the detected master cylinder pressure _Pd
A divider 27 that obtains a ratio ( _Pb / _Pd ) by dividing by the following _formula: and a difference Δ between the ratio ( _Pb / _Pd ) and the input command Vfd.
V - subtracter 25 _{(= V fd (P b /} P d)) to calculate the
And the compensation command V _p of the input command V _fd for reducing ΔV
24, and an adder 26 that adds the input command V _fd and the compensation command V _{p at the previous} stage of the command conversion unit 21.
And

The control unit 20 according to the present embodiment can be configured as a control system for performing so-called PI control or PID control. It is also possible to use a more advanced control system, for example, a robust control system such as H∞ control or two-degree-of-freedom control, a neural computer, a fuzzy control system, or an applied control system.

Further, the compensator 24 calculates ΔΔ
It can be configured as a proportional control system for calculating a V _p from V. Of course, an advanced control system as described above can also be used.

Next, the operation of the present embodiment will be described. If the calculated input command V _fd is not compensated for at all, A
The actual brake pressure realized by the BS actuator 22 is usually delayed with respect to the input command as shown in FIG.

However, in the present embodiment, the compensator 24
But it calculates the compensation command V _p to reduce the difference between the actual average brake pressure P _b detected by the mean braking pressure P _bc and the average brake pressure detector 23 corresponding to the input command V _fd, wherein the compensation The input command V _fd is compensated by the command. Thus, the actual brake pressure P _b is, the brake pressure P _bc corresponding to the input command before being compensated, namely, as a brake pressure to match or substantially match the ΔG 0 is more accurately achieved.

When the compensator 24 is configured as a proportional controller, the command signal shown in FIG. 3A is compensated like the command signal shown in FIG. 3C, and as a result, the brake pressure responding to the command signal is increased. As shown in FIG. 3D, the brake pressure substantially matches the brake pressure according to the command value of the command signal in FIG. That is, the brake pressure is controlled without delay with respect to the input command.

As a result, in the present embodiment, the advantage of the above-described prior art that the highly accurate and stable antilock brake control can be performed regardless of the road surface condition can be further improved.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the antilock brake control device according to the above-described embodiment will be described below.

FIG. 2 shows the configuration of the antilock brake control device according to this embodiment.

As shown in FIG. 2, as an input the actual hole cylinder pressure P _b detected by the oil pressure sensor mounted on each vehicle in the vehicle 50, the brake pressure differential small amplitude P _v
A brake pressure differential small-amplitude detector 36 for detecting the, the mean braking pressure detector 32 for detecting an average brake pressure P _m, composed.

The average brake pressure detecting section 32 can be constituted by a low-pass filter for smoothing the excitation vibration of the wheel cylinder pressure, or can be obtained by averaging time-series data for one cycle of the excitation frequency. it can.

Assuming that the sampling period of the control system is 4 [ms], the period of the excitation frequency 41.7 [Hz] is 6 sample points, and the sample data at 4 [ms] of the wheel cylinder pressure is 6 points. By averaging, the average brake pressure can be detected.

The brake pressure minute amplitude detector 36 detects the minute vibration amplitude of the wheel cylinder pressure output from the brake oil pressure sensor. The resonance frequency component can be extracted by providing a band-pass filter having a frequency of 41.7 [Hz] as a center frequency, and performing full-wave rectification and DC smoothing on the output. Further, time series data of an integral multiple of a cycle, for example, 24 [ms] of one cycle and 48 [ms] of two cycles are continuously taken in, and correlated with a unit sine wave and a unit cosine wave of 41.7 [Hz]. , The resonance frequency component can be extracted.

[0044] Incidentally, the wheel speed omega _w is obtained by processing the signals from the wheel speed sensor (not shown) attached to the respective wheels of a vehicle 50. For example, a detection signal of a wheel speed sensor can be converted into a digital signal by an A / D converter, and the signal can be read into a computer and processed. An analog signal processing circuit or a digital counter circuit can be provided outside the sensor. By configuring, for example, the wheel speed can be detected.

Next, anti-lock brake control apparatus of FIG. 2, the wheel speed micro amplitude detector 38 for detecting an amplitude omega _v of small vibration component from the wheel speed omega _w, the wheel speed micro amplitude detector 38 detects the wheel speed small amplitude omega _v and the brake pressure differential small amplitude brake pressure derivative estimator 36 calculates a small amplitude P _v
Fine gain G _d and fine gain calculation unit 40 for calculating a, a PI controller 42 for calculating a mean braking pressure reference value P _mc on the basis of the calculated micro gain G _d, the average brake pressure reference value P _mc based on a table 44 for obtaining a pressure increase, pressure reduction time of the valve from the pressure increasing time t _i of the valve obtained from the table 44, the current for outputting a command current I _cmd to control the valve at decompression time t _r Controller 46
And an ABS actuator 48 (see FIG. 4) in which the pressure increase / decrease time of the valve is controlled by the command current _Icmd .

Further, the anti-lock brake control device calculates a difference ΔP obtained by subtracting the average brake pressure P _m estimated by the average brake pressure detection unit 32 from the average brake pressure reference value P _mc calculated by the PI controller 42. a subtractor 43 for calculating a _m, a proportional controller 45 which calculates a compensation instruction P _K of the difference [Delta] P _m to based on the proportional gain average brake pressure reference value, the compensation command to the mean braking pressure reference value P _mc P _And an adder 47 for adding _K. The output end of the adder 47 is connected to the table 44. That is, the input to the table 44 is an input command (P _mc + P _k ) _obtained by adding the compensation command to the average brake pressure reference value.

Further, the wheel speed minute amplitude detecting section 38 is configured to extract a resonance frequency component of an excitation vibration system composed of a vehicle body, wheels, and a road surface. Except that the processing signal is the wheel speed, the operation is the same as that of the brake pressure minute amplitude detection unit.

The minute gain calculating section 40 calculates the wheel speed minute amplitude.
Wheel speed minute vibration ω obtained by detector 38_vThe brake pressure
Brake pressure minute amplitude P obtained from estimation device 30_vDivided by
To obtain a small gain G_dIs calculated. This embodiment
In the antilock brake control device according to
G_dIs the reference value G_sBreak when trying to fall below
Since it is necessary to reduce the key pressure, the minute gain calculating section 40
Then, the deviation (G _d-G_s) Is a small gain G_dDivided by
The calculated deviation ΔG is calculated and output to the PI controller 42. This
Where ΔG is

[0049]

(Equation 3)

Is as follows. FIG. 8 shows a configuration example of the minute gain calculation section 40 for calculating ΔG. As shown in FIG. 8, fine gain calculation unit 40, a divider 88 dividing the wheel speed small amplitude omega _v brake pressure differential small amplitude P _v, a given reference value G _s output value of the divider 88 ( ω _v / P _v = G _d ) and a divider 90 connected to the output end of the divider 90 and subtracting the output value (G _s / G _d ) of the divider 90 from 1 to calculate as ΔG And a deviation calculator 92 for outputting. The reference value G _s, the friction state between the road surface and the tire braking force peak (the maximum of the coefficient of friction mu; peak mu) is previously stored in memory as the value of the fine gain when trying to approach the And is read from the memory at the time of the calculation of the equation (3).

The approaches a state of slip will surge between the road surface and the tire, since the micro-gain G _d of the resonant-frequency component is smaller than the reference gain G _s, (3) expression of the second term (G
_s / G _d ) suddenly becomes larger than 1, and ΔG takes a large negative value. That is, by using (G _s / G _d ), the detection sensitivity of ΔG for detecting a state where the slip suddenly increases is higher than when the inverse number (G _d / G _s ) is used. Thereby, the PI controller 42 based on this ΔG
Can be controlled accurately.

The output terminal of the small gain calculator 40 is
It is connected to the average brake pressure estimating unit 32, and the calculated small gain _Gd is input to the average brake pressure estimating unit 32.

The PI controller 42 shown in FIG. 2 calculates an average brake pressure reference value _Pmc such that ΔG calculated by the minute gain calculator 40 matches or substantially matches zero. In general, in an ABS device of a real vehicle, it is often impossible to apply a brake pressure greater than a brake pressure due to a treading force of a driver to a wheel due to a hardware configuration of an actuator. It is necessary to design the PI controller 42 so that the brake pressure is rapidly reduced only when the brake pressure due to the driver's depressing force increases and the wheel slip approaches or exceeds the value at which the peak braking force is attained. Here, an example of the configuration of the PI controller 42 is shown in FIG.

As shown in FIG. 9, except for the positive value removal and the out-of-range removal, the PI controller 42 calculates the deviation ΔG

[0055]

Equation 4] comprises a first calculation part for calculating a _{V f = G c (1 +} ω c / s) ΔG (4), has a proportional gain G _c, PI controller integral gain G _c ω _c.

In the portion for calculating the proportional term in equation (4), ΔG
, And a positive value removing unit 94 that outputs only a negative value is interposed. According to the characteristics between the tire road surfaces, when the slip speed increases, the tire moves away from the gripping state and the resonance frequency shifts to the higher frequency side. Therefore, the minute gain G, which is the resonance frequency component of the vibration system including the vehicle body, the wheels, and the road surface, is obtained. _d decreases. Therefore, when a negative value of the actual small gain to the reference value G _s G _d becomes smaller .DELTA.G, i.e. the braking of the brake pressure only when the tire becomes locked state immediately before being braked beyond the peak μ It is intended to be applied.

The part for calculating the integral term in the equation (4) is as follows:
A Laplace arithmetic unit 96 for calculating 1 / s with respect to ΔG;
Ω _c -fold amplifier 98 connected to the output terminal of the Laplace arithmetic unit 96. Then, the positive value removing unit 94
The output terminal of the amplifier 98 is connected to an amplifier 102 of _Gc times via an adder 100 for adding the proportional term and the integral term. With such a configuration, the amplifier 102 has the V
Output _f .

[0058] Here, the time t _r of the pressurization command and the time t _i of increase pressure command, as shown in FIG. 6, because it is defined for the computed average brake pressure, the actual pressure increase, pressure reduction When the master cylinder pressure is 15.5 [MPa], the range of the average brake pressure reference value P _mc for obtaining the time is from the maximum pressure reduction state of 0.5 [MPa] to the maximum pressure increase state of 12 [MPa].
It is necessary to output a value up to about [MPa]. The range of this value is about 0.03 to 0.77 times the master cylinder pressure.

Further, a state in which the deviation ΔG is a positive value equal to or greater than zero means that the slip state of the tire is not approaching a state in which the tire has a peak braking force.
_{When f} becomes 0, the average brake pressure reference value _Pmc needs to output a value that realizes the maximum pressure increase state 12 [MPa].

Therefore, the equation for calculating the average brake pressure reference value _Pmc from _Vf calculated from equation (4) is as follows:

[0061]

P _mc = P _d0 (V _f + V ₀ ) (5) However, P _d0 = 15.5 [MPa] and V ₀ = 0.
77. The average brake pressure reference value P _mc is, so as not to be smaller than the value 0.03 × P _d0 at the maximum reduced pressure, the range of the previously, V _f for calculating the expression (5) -0.74
０0 is required.

In the PI controller 42 for realizing the above-mentioned restrictions, the component for calculating the expression (5) is an out-of-range removing unit 104 for removing a value outside the range of _Vf output from the amplifier 102.
When a V _f of range removal unit 104 outputs, an adder 108 for adding the V ₀ which is input from the other input terminal, which is calculated by the adder 108 _{(V f + V 0) P} d0 And a multiplying amplifier 110.

The out-of-range removing unit 104 determines that _Vf is -0.74
When the value is outside the range of ０0, it is set to a value within the range (the boundary value of the range), and when _Vf is within the above range, the value is output as it is. Note that the output V of the actual controller is
_{Even if} the out-of-range part of _f is removed by the out-of-range removing unit 104, the deviation Δ
G occurs. As a result, there is a possibility that the deviation ΔG becomes an input of the integration element and the integration output increases to diverge.
This causes a large difference between the actual output sum value of the proportional term and the integral term and the value obtained by removing the outside of the range, and causes problems such as a delay in the output of the entire PI controller.

Therefore, there is provided a deviation calculator 106 for calculating a value obtained by subtracting the output value of the out-of-range removing unit 104 from the input value of the out-of-range removing unit 104. Connect to By returning the output value of the deviation calculator 106, that is, the value of the portion removed by the out-of-range removal unit 104, as the initial value of the integral term, stable control can be realized.

The output end of the PI controller 42 is connected to the master cylinder pressure estimating unit 34, to which the calculated average brake pressure reference value _Pmc is input.

The table 44 shown in FIG.
FIG. 4B is a table showing the functional relationship between the average brake pressure and the pressure increase / decrease time shown in FIG.
4 can be obtained between the pressure increase corresponding to the mean braking pressure reference value P _mc calculated by the PI controller 42 t _i and decompression time t _r by reference to the.

The current controller 46 controls the pressure increase time t _i obtained in accordance with the calculated average brake pressure reference value P _mc ,
To match the decompression time t _r, pressure increasing time of the valve of the ABS actuator 48, controls the decompression time.

As specific contents of the control, the mode of pressure increase and the mode of pressure decrease are switched every half cycle T / 2 of the cycle T of minute excitation (for example, 24 [ms]). moment between the pressure boosting t _i of the switching outputs pressure increase-pressurization command each by time of the pressure reduction time t _r, the remaining time of T / 2 outputs a holding command. With such an operation command, it is possible to easily control the minute excitation of the brake pressure and the control of the average brake pressure. FIG. 10 shows an outline of an operation command to the valve of the ABS actuator 48 in this control example (an operation example of the brake pressure control device).

For counting the pressure increasing / decreasing time, a counter timer which is reset to zero by mode switching may be provided, or the gain of the integrator which is reset to zero by mode switching may be increased by the pressure increasing time t _i and the pressure decreasing time. is inversely proportional to t _r is varied, it may be used time to reach a certain threshold.
If a command to the valve can be generated, a control current corresponding to each state is commanded to the ABS actuator 48.

Next, the operation of the present embodiment will be described. ABS
In apparatus, wheel speed micro amplitude detector 38, a wheel speed sensor (not shown) detects the amplitude of the resonant-frequency component of the wheel speed omega _w detected. Then, fine gain calculation section 40 calculates the micro-gain G _d from the amplitude value of the resonance frequency component of the brake pressure differential small amplitude P _v and wheel speed omega _w, the calculated fine gain G _d average brake pressure estimator 32 and transfers to, calculates the deviation ΔG based on and a small gain G _d and the reference gain G _s (3) expression.

Then, the PI controller 42 controls the small gain
The deviation ΔG calculated by the calculation unit 40 is made to coincide with or substantially coincide with zero.
Average brake pressure reference value P_mcIs calculated. This flat
Equivalent brake pressure reference value P_mcIs the master cylinder pressure estimator 3
4. The data is transferred to the subtractor 43 and the adder 47. Subtractor 4
3 is the average brake pressure reference value P_mcFrom the average
Average brake pressure P estimated by key pressure estimation unit 32_mDifference with
Minute ΔP_m= (P_mc−P _m) Is calculated. Next, proportional control
The device 45 calculates the difference ΔP_mThe compensation finger based on the proportional gain
Order P_kIs calculated as Then, the adder 47 outputs the average
Rake pressure reference value P_mcAnd compensation command P_kAnd add
Command value (P_mc+ P_k) Is output to the table 44.

Then, the input command value (P _mc + P _k ) is converted by the table 44 into the pressure increasing / decreasing time of the valve. Next, the current controller 46 _sets the command value (P _mc + P
pressure increase, pressure reduction time t _i corresponding to _k), the t _r, converted to an operation command such as shown in FIG. 10, ABS actuator 4
8 The ABS actuator 48 generates a brake pressure corresponding to the command value (P _mc + P _k ) to the wheel cylinder by increasing / decreasing the valve according to the operation command of FIG.

With the above-described control, if the braking force is applied beyond the maximum braking force (when the braking torque gradient in FIG. 7 is 0), the resonance frequency shifts to the high frequency side. and the road surface reduces fine gain G _d at the resonance frequency when the grip state, since a negative value ΔG equation (3), the braking force is rapidly decreased, it is possible to prevent the locking of the tires . Further, since control is performed so that ΔG is made equal to zero, braking is performed while the peak value of the braking force shown in FIG. 7 is maintained, and the braking distance and the braking time are reduced.

As described above, in the ABS device according to the present embodiment, the braking force is controlled based on the resonance characteristics of the vibration system including the vehicle body, the wheels, and the road surface.
The change in the braking force is more continuous and smoother than that in the system in which the braking force is reduced after the wheel lock is detected as in the S device. Also, because it is based on resonance characteristics,
Stable control is possible even for road surface changes, and can be realized with a single control logic.

Further, in this embodiment, proportional control is performed so as to reduce the difference ΔP _m between the actually estimated average brake pressure P _m and the average brake pressure reference value P _mc , which is a command value of the brake pressure. Since the command value of the brake pressure is compensated, the response delay of the average brake pressure supplied by the ABS actuator 48 can be reduced. That is, the actual average brake pressure approaches the brake pressure commanded by the average brake pressure reference value _Pmc (see FIG. 3). Therefore, an accurate anti-lock brake operation with no operation delay is possible.

In this embodiment, as shown in FIG. 10, the pressure increase / decrease mode is alternately switched at regular intervals, and the control of the brake pressure is performed by adjusting the pressure increase time and the pressure decrease time in each mode. Thus, continuous control of the brake pressure becomes possible. In addition, the switching frequency of each mode (the frequency of the minute excitation) is relatively high at 40 [Hz], and can be made with a very small amplitude at which the resonance characteristic can be detected. I can feel it,
Kickback can be prevented. As a result, the ABS control can be performed with higher performance without significantly changing the vehicle behavior.
Furthermore, continuous control of the average brake pressure becomes possible with the two valve configuration of the pressure increasing valve and the pressure reducing valve used in the current ABS device, and the change of hardware can be suppressed.

[0077]

As described above, according to the present invention, the input command to the control valve is compensated so that the difference between the brake pressure corresponding to the input command and the actual brake pressure is reduced. Thus, an excellent effect that the responsiveness of the brake pressure can be improved is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an antilock brake control device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of an antilock brake control device according to an embodiment of the present invention.

3A and 3B are diagrams showing a command and a response of a brake pressure according to the related art and the present invention, wherein FIG. 3A responds according to a conventional brake pressure command signal, and FIG. 3B responds according to a conventional command signal; The actual brake pressure change, (c) shows the brake pressure command signal in the present invention, and (d) shows the actual brake pressure change responding according to the command signal in the present invention.

4A and 4B are diagrams showing a valve configuration of an ABS actuator, wherein FIG. 4A shows a configuration with one 3-position valve;
(B) is a figure which shows the structure with two 2-position valves.

FIG. 5 is a diagram showing an equivalent model of a vibration system including a vehicle body, wheels, and a road surface according to the embodiment of the present invention.

FIGS. 6A and 6B are graphs showing characteristics of pressure increase / decrease time for constant brake pressure minute amplitude, wherein FIG. 6A shows a relationship between average brake pressure and pressure increase time, and FIG. It is a figure showing relation with time.

[7] and the slip speed [Delta] [omega, a diagram showing the relationship between the inclination of the braking torque T _b and braking torque T _b.

FIG. 8 is a block diagram illustrating a configuration example of a minute gain calculation unit included in the antilock brake control device according to the embodiment of the present invention.

FIG. 9 is a block diagram illustrating a configuration example of a PI controller included in the antilock brake control device according to the embodiment of the present invention.

FIG. 10 is a view showing an operation command to a valve of an ABS actuator constituting the antilock brake control device according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 20 control unit 21 command conversion unit 22 ABS actuator 23 average brake pressure estimation unit 24 compensator 25 subtractor 26 adder 30 brake pressure estimation unit 32 average brake pressure estimation unit 34 master cylinder pressure estimation unit 36 brake pressure minute amplitude estimation unit 38 Wheel speed minute amplitude detector 40 Minute gain calculator 42 PI controller 43 Subtractor 44 Table 45 Proportional controller 46 Current controller 47 Adder 48 ABS actuator

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Eiichi Ono 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Institute, Inc. 41 Toyota Chuo R & D Co., Ltd., No. 41, Chuchu-Yokomichi (72) Inventor Hiroyuki Yamaguchi 41 Toyota Chuo Research Laboratories, Inc.

Claims (1)

[Claims] A control valve for controlling an average brake pressure according to an input command; a micro-excitation means for micro-excitation of a brake pressure at a predetermined frequency; and a wheel speed when the brake pressure is micro-excited by the micro-excitation means. Detecting means for detecting a vibration characteristic of the vehicle, based on the vibration characteristic of the wheel speed detected by the first detecting means, a slip coefficient at which a friction coefficient between the wheel and the road surface becomes substantially a peak value or less. Control means for calculating an input command to the control valve such that the slip ratio of the control valve is calculated, wherein the actual value as a response of the control valve to the input command calculated by the control means is provided. A second detecting means for detecting the average brake pressure of the first and second brake means, and an average brake pressure corresponding to the calculated input command and an actual brake pressure detected by the second detecting means. An anti-lock brake control device comprising: a compensation means for calculating a compensation command for reducing a difference from an average brake pressure, and compensating the input command with the compensation command.