JP2002225690A - Vehicular brake system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a time lag in braking torque corresponding to an indicator current. SOLUTION: A vehicular brake system comprises an indicator current computing part for computing an indicator current corresponding to a depression state of a brake pedal, and a compensating current adding part for adding a positive compensating current to the indicator current at the buildup of the indicator current or before a transition from the buildup to a steady state, and adding a negative compensating current in the transition to the steady state; and drives a brake driving actuator on the basis of the indicator current to which the compensating currents are added. This can eliminate a time lag in braking torque resulting from moment of inertia, damping loss and friction loss of the brake driving actuator, and can reduce a resultant overshoot.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to changing the amount of current supplied to an actuator (for example, a motor for moving a brake pad to a brake rotor, etc.) for generating a braking force in accordance with the state of depression of a brake pedal. The present invention relates to a vehicle brake device that electrically performs a braking operation.

[0002]

2. Description of the Related Art In a vehicle brake device that performs an electrical braking operation, a command current flowing to a brake control actuator is controlled by open control in accordance with a depression state of a brake pedal, and the instruction current is controlled according to the depression state of the brake pedal. Wheel braking force is obtained.

[0003]

However, simply controlling the command current by the open control causes problems such as time delay and overshoot caused by the characteristics of the actuator for brake control, and control failure due to the resonance phenomenon caused by the overshoot. Can not prevent. Each of the above problems will be described with reference to FIGS.

FIG. 28A shows a time delay and an overshoot caused by the inertial force of the brake control actuator. As shown in this figure, even if the command current indicated by the solid line is output, the inertia force of the actuator acts, so that at the time of startup (see region 1 in the figure), the command value of the braking torque corresponding to the command current is reduced. On the other hand, a time delay occurs in the braking torque, and when the vehicle shifts to the steady state (see region 2 in the figure), an overshoot that exceeds the indicated value occurs.

When an overshoot occurs, the actual braking torque fluctuates around the indicated value even if the indicated value is constant as shown in FIG. Even if the indicated value is reduced as shown in B in the figure to reduce the overshoot, a resonance phenomenon that a new overshoot is generated as shown in b in the figure may occur.

FIG. 28 (b) shows a time delay caused by friction loss and damping loss of the brake control actuator. As shown in this figure, even if the indicated value indicated by the solid line is set, friction loss (eg, loss due to motor rotational friction) and damping loss (eg, loss due to motor damping force) of the brake control actuator occur. To do
Due to these energy losses, a time delay occurs in the actual braking torque with respect to the command value between the time of startup and the transition to the steady state (see region 3 in the figure).

Also, a gap (for example, a gap between a brake pad and a brake rotor) is provided in a brake driving actuator, such as a disc brake in which a braking device generates a braking force by pressing a brake pad against a brake rotor. ) Is present, FIG.
As shown in (c), a time delay occurs in which the braking torque can be generated only some time after the command current is output, and an overshoot due to this time delay also occurs.

Furthermore, when the command current exceeds the capacity of the brake driving actuator, the actual output value cannot catch up with the command current, and stable control cannot be performed or overshoot may occur. .

In view of the above, it is an object of the present invention to suppress a time delay occurring in an actual braking torque with respect to an instruction value of a braking torque corresponding to an instruction current. It is another object of the present invention to reduce overshoot and prevent control failure due to a resonance phenomenon caused by overshoot. It is another object of the present invention to suppress a time delay of a braking torque caused by a gap between the brake driving actuators. It is another object of the present invention to perform stable control in consideration of the capability of a brake driving actuator.

[0010]

According to the first aspect of the present invention, when the brake pedal is depressed, the braking torque is increased by driving the brake driving actuator (3). In a vehicle brake device configured to generate a command current, a command current calculation means (4) for calculating a command current according to a depressed state of a brake pedal, and a compensation current is added to the command current when the command current changes. And a compensation current adding means (5) for driving the brake driving actuator based on the command current to which the compensation current has been added.

As described above, by adding the compensation current to the command current when the command current changes, the time delay of the braking torque due to the moment of inertia or at least one of the damping loss and the friction loss of the brake driving actuator is reduced. It is possible to eliminate the time delay of the braking torque generated due to this, and to reduce the overshoot due to this.

According to the fourth aspect of the present invention, a command current calculating means (4) for calculating a command current in accordance with a depression state of a brake pedal, and a compensation for adding a compensation current to the command current when the command current rises. And a current adding means (5) for driving the brake driving actuator based on the command current to which the compensation current has been added.

As described above, by adding the compensation current to the command current when the command current rises, the time delay of the braking torque due to the moment of inertia can be eliminated, and the overshoot due to this can be reduced. It becomes possible.

According to a sixth aspect of the present invention, there is provided an instruction current calculating means (4) for calculating an instruction current according to a depressed state of a brake pedal, and when the state shifts to a steady state after the instruction current rises. A compensation current adding means (5) for adding a compensation current to the command current is provided, and the brake driving actuator is driven based on the command current to which the compensation current has been added.

As described above, when the command current shifts to the steady state, the compensation current is added to the command current. Therefore, overshoot that can occur at this time can be reduced.

According to the present invention, a command current calculating means (4) for calculating a command current according to a depressed state of the brake pedal, and a command current calculating means (4) for starting the command current and transitioning to a steady state. And a compensating current adding means (5) for adding a compensating current to the command current, wherein the brake driving actuator is driven based on the command current to which the compensating current has been added. I have.

As described above, if the compensation current is added to the command current after the rise of the command current and before transition to the steady state, the time delay of the braking torque caused by the damping loss and the frictional loss can be obtained. Can be suppressed.

According to the ninth aspect of the present invention, an instruction current calculating means (4) for calculating an instruction current according to a depression state of the brake pedal, and whether or not the brake pedal is depressed is determined. Brake pedal depression detection means (1, 10) and pre-current addition means (11) for sequentially adding positive and negative compensation currents to the command current when it is detected that the brake pedal is depressed. The brake driving actuator is driven based on the command current to which the compensation current is added.

As described above, when it is detected that the brake pedal is depressed, the positive and negative compensation currents are sequentially added to the command current, so that the braking torque caused by the gap existing in the brake control actuator is obtained. Time delay can be prevented.

In this case, when the stepping on the brake pedal is stopped from the state where the stepping on the brake pedal has been performed, the pre-current load means is used.
The negative and positive compensation currents can be sequentially added to the command current.

According to this configuration, when the depression of the brake pedal is stopped, the gap of the brake control actuator can be returned to the original state immediately. Therefore, the depression of the brake pedal is repeated many times. Can also respond to it.

According to the eleventh aspect of the invention, when the command current to which the compensation current is added exceeds a predetermined upper limit value (C), the command current to which the compensation current is added falls below the upper limit value. Sometimes, the instruction current to which the compensation current has been added is
Further, an undercurrent assisting means for adding an amount exceeding the upper limit value is provided.

In this way, when the command current to which the compensation current has been added falls below the upper limit value, it is possible to compensate for the shortage current when exceeding the upper limit value.

According to the twelfth aspect of the present invention, the command current calculating means (4) for calculating a command current according to the depressed state of the brake pedal and the limit braking torque which can be generated by the brake driving actuator are estimated. The estimating means compares the target braking torque required for the command current calculated by the command current calculating means with the limit braking torque estimated by the estimating means, and calculates the difference between the limit braking torque and the target braking torque. Means for specifying a point at which the sign is inverted, and compensation current adding means (1) for adding a compensation current to the indicated current at the point at which the sign is inverted.
4).

As described above, the point at which the sign of the difference between the limit braking torque and the target braking torque is reversed is specified, and at that point, the compensation current is added to the command current to generate the point. Overshoot can be reduced.

According to a thirteenth aspect of the present invention, when the command current is set to a value exceeding the capability of the brake driving actuator, the slope of the command current is limited. As described above, by limiting the gradient of the command current, stable control can be performed in consideration of the capability of the brake driving actuator.

The reference numerals in the parentheses of the above means indicate the correspondence with the specific means described in the embodiments described later.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows a block configuration of a vehicle brake device to which one embodiment of the present invention is applied. The vehicle brake device according to the present embodiment includes a pedaling force sensor 1, an electronic control unit (hereinafter, referred to as an ECU) 2, and a brake driving actuator 3 for generating a braking force.

The pedal force sensor 1 detects the pedal depression force when the brake pedal is depressed, and outputs a detection signal corresponding to the pedal depression force.

The ECU 2 performs various arithmetic processes based on the detection signal from the pedaling force sensor 1. Hereinafter, a specific configuration of the ECU 2 will be described. The ECU 2 includes an instruction current calculator 4,
A compensation current adder 5, a drive current calculator 6, and a drive circuit 7 are provided.

The command current calculation section 4 corresponds to a command current calculation means. The command current calculation unit 4 calculates a command current according to the pedal effort based on the detection signal from the pedal effort sensor 1.

The compensation current adding section 5 corresponds to a compensation current adding means. The compensation current adder 5 calculates the compensation current and adds the calculated compensation current to the command current calculated by the command current calculator 4 to calculate the post-compensation command current. That is, as compared with the command current set by the open control as described above, the actual current has a time delay caused by the inertial force of the brake driving actuator 3 and the time caused by the friction loss and the damping loss. Since there is a delay and there is a possibility that an overshoot due to the inertial force of the brake driving actuator 3 may occur, the compensation current adding unit 5 generates a compensation current for compensating the time delay and an overshoot. A compensation current for reduction is added to the command current.

The drive current calculator 6 superimposes a dither current on the compensated instruction current as necessary. The dither current is a current having a periodicity superimposed on the command current (for example, a current having a rectangular waveform or a current having a rectangular waveform) in order to eliminate hysteresis existing in the relationship between the command current flowing to the brake driving actuator 3 and the braking torque. Triangular waveform). In addition, the drive current calculation section 6 sets an upper limit value (for example, 10 A) or the like to the post-compensation instruction current as necessary.
This prevents an overcurrent from flowing through the brake driving actuator 3. And the driving circuit unit 7
Is designed to allow the final command current to flow to the brake driving actuator 3 in accordance with the calculation result of the drive current calculation unit 6.

Next, the compensation of the time delay caused by the inertial force, the friction loss or the damping loss and the calculation of the compensation current for reducing the overshoot performed by the compensation current adder 5 will be described with reference to FIG. I do.

FIG. 2 shows the control theory of the braking torque generated with respect to the command current. In FIG. 2, the upper half of the drawing shows a model representing loss, and the lower half of the drawing shows loss compensation. Is shown.

When the command current is set according to the depression state of the brake pedal, the command current appears as a braking torque (point a). At this time, since the moment of inertia, damping loss, and friction loss exist in the brake driving actuator 3, the actual braking torque (point b) changes depending on these.

When these losses are modeled, the value obtained by dividing the braking torque by the moment of inertia (point c) becomes the motor rotation angular acceleration, and the integral value of this motor rotation angular acceleration (point d) becomes the motor rotation angular velocity. Since the integral value (point e) of the motor rotation angular speed becomes the motor rotation angle, the attenuation loss and the friction loss depending on the motor rotation angular speed are obtained from a map related to the motor rotation angular speed.

Therefore, these moments of inertia, damping loss,
The required braking torque can be generated by adding a compensation current to the command current so as to compensate for the variation in the braking torque due to the friction loss.

This variation is compensated for by a loss compensation model, and a target motor rotation angle (point f) is obtained from a map associated with the indicated current.

Next, a target motor rotational angular velocity (point g) is obtained from a differential value of the target motor rotational angle, and based on the target motor rotational angular velocity, a map is used in which the target motor rotational angular velocity is related to attenuation loss or friction loss. The fluctuation of the braking torque for the damping loss or the friction loss (point h) is obtained, and this is divided by the torque constant to obtain the damping / friction correction current (point i) corresponding to the compensation current for the damping loss or the friction loss. Can be

Further, a target motor rotation angular acceleration (point j) is obtained from a differential value of the target motor rotation angular velocity, and a fluctuation (point k) of a braking torque caused by an inertia moment is obtained from the target motor rotation angular acceleration. By dividing this by the torque constant, an inertia correction current (point l) corresponding to the compensation current for the inertia moment is obtained.

In this manner, the damping / friction correction current and the inertia correction current are obtained. By adding these to the command current in advance, even if the moment of inertia, the damping loss, and the friction loss exist, they are removed. It is possible to generate the required braking torque with compensation.

The command current compensation control executed by the vehicle brake device having the configuration shown in FIG. 1 based on such a control theory will be described. FIG. 3 shows a flowchart of the command current compensation control, and FIG. 4 shows, as waveforms related to each processing in FIG. 3, a command current waveform, a damping / friction correction current waveform, an inertia correction current waveform, and a post-compensation command current. Examples of waveforms and braking torque waveforms are shown, and the description will be made based on these drawings.

First, at step 100, it is determined whether or not the stop switch (STPSW) is ON.
This determination may be made, for example, based on whether or not the pedaling force obtained by the pedaling force sensor 1 is equal to or greater than a predetermined value. Although not provided in the present embodiment, a stop switch sensor for detecting that the brake pedal is pressed down May be used. If a positive determination is made in this step, the process proceeds to step 110, and if a negative determination is made,
Since the brake pedal has not been depressed, the routine proceeds to step 190, where the post-compensation instruction current is set to 0, and the process ends.

In the following step 110, after the detection signal from the treading force sensor 1, that is, the treading force signal is read,
In step 120, an instruction current is calculated in accordance with the read pedal force signal. The calculation of the command current is performed by the command current calculation unit 4 provided in the ECU 2, and the command current as shown in FIG.

Then, the processing of steps 130 to 170 is performed. The processing of steps 130 to 170 is performed based on the control theory of FIG. 2 described above. First, in steps 130 and 140, a target motor rotation angle and a target motor rotation angular velocity are calculated based on the calculated instruction current. Specifically, a target motor rotation angle corresponding to the calculated instruction current is obtained based on a map in which the instruction current and the target motor rotation angle are related, and the target motor rotation angle is differentiated to obtain the target motor rotation angle. Calculate the rotational angular velocity. Then, based on the obtained target motor rotation angle, at step 150, the damping / friction correction current is calculated. Thus, a damping / friction correction current as shown in FIG. 4B is obtained. That is, a damping / friction correction current (positive compensation current) that compensates for the instruction current during this period is determined so as to eliminate the time delay that occurs between the rise of the instruction current and the transition to the steady state.

In step 160, the target motor rotational angular acceleration is calculated. Specifically, a target motor rotation angular acceleration is obtained by differentiating the target motor rotation angular velocity. Then, an inertia correction current is calculated in step 170 based on the target motor rotation angular acceleration.
Thus, an inertia correction current as shown in FIG. 4C is calculated. In other words, the moment of inertia causes a time delay at the rise of the command current, and an overshoot occurs at the time of transition to the steady state. An inertia correction current that is a negative compensation current that causes the inertia correction current to be obtained is required.

In the following step 180, a compensation current addition operation is performed by adding the damping / friction correction current and the inertia correction current to the command current to obtain a post-compensation command current. This compensation current addition operation is performed by the compensation current addition unit 5. Thus, as shown in FIG. 4D, the post-compensation command current has a waveform obtained by adding the damping / friction correction current and the inertia correction current to the command current.

When the compensation current addition operation is performed in this way, the processing is terminated, and the post-compensation instruction current obtained by the compensation current addition operation is sent to the drive current operation section 6, where necessary. After the current is superimposed and the upper limit is set, the current is output to the brake driving actuator 3 through the driving circuit unit 7. As a result, as shown in FIG. 4E, a braking torque having the same waveform as the command current initially set according to the pedal depression force is obtained, and no compensation is performed as shown by the dotted line in the figure. The occurrence of time delay and overshoot as in the case can be suppressed.

As described above, in anticipation of the loss due to the moment of inertia, damping loss, friction loss, etc., the compensation current corresponding to the loss is added to the command current initially set according to the pedaling force, so that the current is set first. It is possible to obtain a braking torque corresponding to the specified instruction current. As a result, the time delay of the actual current with respect to the command current can be suppressed, the overshoot can be reduced, and control failure due to the resonance phenomenon due to the overshoot can be prevented.

Although the rising of the command current is described here, the falling of the command current is also considered at the time of the fall in anticipation of the loss due to the moment of inertia, damping loss, frictional loss, and the like. For example, a negative compensation current can be applied. As a result, even at the time of falling, the loss can be compensated, a braking torque corresponding to the initially set instruction current can be obtained, and the effect of suppressing the time delay and reducing the overshoot can be obtained. That is, when the command current changes, the above effect can be obtained by adding a compensation current corresponding to the change to the command current.

Although an example of the compensation current to be added to the instruction current at the time of rising is described above, the sign of the compensation current is merely an example, and the sign of the compensation current is reversed according to the manner of variation of the instruction current. In some cases. For example, regarding the inertia compensation, when the spring loss of the brake driving actuator 3 is nonlinear, or when the speed of the command current changes in the course of rising or falling, the negative becomes negative at the rising and becomes positive at the falling. Become.

(Second Embodiment) FIG. 5 shows a block configuration of a vehicle brake device to which a second embodiment of the present invention is applied. The vehicle brake device according to the present embodiment is different from the first embodiment in that a stop switch sensor 10 and a pre-current drive determining unit 11 are provided, and a compensation current adding unit 5 shown in FIG. 1 is provided. Not that different. Since other configurations are the same as those of the first embodiment, the same components are denoted by the same reference numerals as in FIG. 1 and the description is omitted.

The stop switch sensor 10 detects whether or not the brake pedal has been depressed and a braking request has been made.
To tell.

The pre-current drive determining unit 11 corresponds to a pre-current adding unit. The pre-current drive determination unit 11 is provided in the ECU 2, receives a detection signal from the stop switch sensor 10, determines whether or not to add a pre-current, and calculates the pre-current. The pre-current is a current to be added to the command current in the disk brake in order to eliminate a time delay of the braking torque caused by the existence of a gap between the brake pad and the brake rotor. Specifically, the stop current is turned off by the stop switch sensor 10 in the pre-current.
Is detected to be switched from ON to ON, and O
When the switching from N to OFF is detected, it is generated at the same time, and when it is switched from OFF to ON, it is generated in the form of a pulse in the order of positive and negative, and ON
When switched from OFF to OFF, pulses are generated in the order of negative and positive.

Next, the pre-current calculation control executed by the vehicle brake device having the structure shown in FIG. 5 will be described. FIG.
FIG. 7 shows a flowchart of the pre-current calculation control, and FIG. 7 shows ON / OFF waveforms of the stop switch, a command current waveform, a waveform obtained by adding the pre-current to the command current, and a brake related to the respective processes in FIG. An example of the stroke amount and the driving force waveform of the driving actuator 4 will be described, and the description will be made based on these drawings.

First, the brake pedal is depressed, and FIG.
Assuming that the stop switch is turned ON as shown in FIG. 7A, an instruction current as shown in FIG. 7B is set according to the depression state of the brake pedal at that time.
This process is the same as steps 100, 110, and 190 shown in FIG. 3 of the first embodiment. Then, each processing shown in FIG. 6 is performed together with the processing for setting the instruction current. This process is performed by the pre-current drive determination unit 11.

First, in step 200, it is determined based on the detection signal from the stop switch sensor 10 whether or not the stop switch has been turned on this time, that is, whether or not the stop switch has been turned on. And step 200
If the determination is affirmative, the routine proceeds to step 210, where the timer T
The constant A is set to 1 and the routine proceeds to step 220.

In step 220, the pre-current pattern 1
Is calculated based on the pre-current. Pre-current pattern 1
Means that the stop switch is turned OFF to O
N is set when switched to N.
This means a pattern in which the pre-current is generated in the form of a pulse in the negative order.
The calculation of the pre-current according to the elapsed time from when the FF is switched to ON is performed.

On the other hand, if a negative determination is made in step 200, the flow advances to step 230 to decrement the value of the timer T1, and then to step 240, where it is determined whether or not the value of the timer T1 is not zero. And step 24
If a negative determination is made at 0, it is the timing to add the pre-current in the pre-current pattern 1 and therefore, step 2
Proceeding to 20, the above-described calculation of the pre-current is performed.

In the following step 250, it is determined based on the detection signal from the stop switch sensor 10 whether or not the stop switch has been turned off this time, that is, whether or not the stop switch has been switched from on to off. And step 25
If an affirmative determination is made at 0, the routine proceeds to step 260, where a constant B is set in the timer T2, and the routine proceeds to step 270.

In step 270, the pre-current pattern 2
Is calculated based on the pre-current. Pre-current pattern 2
Means that the stop switch is turned ON and OFF as described above.
F is set when switched to F, negative,
This means a pattern in which the pre-current is generated in the form of pulses in the positive order.
The calculation of the pre-current according to the elapsed time from when the switching from N to OFF is performed.

On the other hand, if a negative determination is made in step 250, the process proceeds to step 280 to decrement the value of the timer T2, and then proceeds to step 290 to determine whether the value of the timer T2 is not zero. And step 29
If a negative determination is made at 0, it is the timing to apply the pre-current in the pre-current pattern 2 yet.
Proceeding to 70, the above-described calculation of the pre-current is performed.

When the pre-current calculation control is performed in this manner, the drive current calculation section 6 adds the pre-current calculated by the pre-current drive determination section 11 to the command current calculated by the command current calculation section 4. Are added, the command current is compensated as shown in FIG. 7 (c), the dither current is superimposed and the upper limit is set as required, and the brake driving actuator is 3 is output.

As described above, the pre-current is applied when the stop switch is switched from OFF to ON. For this reason, as shown in FIG.
As soon as the stop switch is turned on, the gap (clearance) between the brake pad and the brake rotor can be instantaneously reduced, and the braking force can be generated without time delay as shown in FIG. At the same time, it is possible to reduce the overshoot caused by the time delay.

Also, the stop switch is changed from ON to OFF.
When the stop switch is turned off, the brake pad is returned to the original position at the same time as the stop switch is turned off, as shown in FIG. A gap can be provided between the brake rotor and the brake rotor. Therefore, even if the brake pedal is used many times in a short time, the pre-current pattern 1 described above is not set before the brake pad returns to the original position.

In a configuration in which two or more wheels can operate independently, the operation timing of the pre-current described above,
The amount of actuation can also be varied. For example, the operation timing of the pre-current is advanced on the rear wheel side, and is delayed on the front wheel side. In this way, it is possible to reduce the peak of the initial shock generated by performing the pre-current control in each wheel at the same timing.

(Third Embodiment) FIG. 8 shows a block configuration of a vehicle brake device to which a third embodiment of the present invention is applied. The vehicle brake device according to the present embodiment combines the configurations of the vehicle brake devices according to the first and second embodiments.

As shown in FIG. 8, the first and second embodiments can be combined. In this case, both the command current compensation control shown in FIG. 3 and the pre-current calculation control shown in FIG. 6 can be performed. In this case, the instruction current finally output from the drive circuit unit 7 has a waveform obtained by adding the pre-currents in the pre-current patterns 1 and 2 to the post-compensation instruction current shown in FIG. Becomes

(Fourth Embodiment) In this embodiment, an undercurrent assisting function is added to the vehicle brake device shown in the first to third embodiments. However,
Here, as in the third embodiment, a case is shown in which the undercurrent auxiliary control is performed in a case where the first and second embodiments are combined.

In the case where the command current that can be finally output from the drive circuit unit 7 has an upper limit, if the requested command current is higher than the limit, the command current that can be actually output from the drive circuit unit 7 becomes insufficient. Will happen. For this reason, in the present embodiment, control is performed such that the insufficient current is assisted when the requested instruction current falls below the upper limit.

FIG. 9 shows a flow chart of the undercurrent auxiliary control, which will be described with reference to FIG. It should be noted that the insufficient power auxiliary control is performed by the drive current calculation unit 6.

First, in step 300, the driving current 1, that is, the required indicating current is calculated from the compensated indicating current and the pre-current pattern 1 and the pre-current pattern 2.

Next, at step 310, it is determined whether or not the calculated drive current 1 exceeds the upper limit value C of the command current. If an affirmative determination is made in step 310, the process proceeds to step 320, in which a difference between the driving current 1 and the upper limit C is set as an undercurrent. At this time, if an undercurrent already exists in the previously performed processing,
As the undercurrent, a value obtained by adding the above difference to the previous undercurrent is set. Then, the process proceeds to step 330, where the drive current (that is, the actually output instruction current) is set to the upper limit value C.

On the other hand, if a negative determination is made in step 310, the process proceeds to step 340, where the difference between the upper limit value C and the drive current 1 is determined in step 320 described above or step 36 described later.
It is determined whether the current is equal to or greater than the undercurrent set in steps 0 and 380. Then, if a positive determination is made in step 340,
Proceeding to step 350, the drive current is set to a value obtained by adding the undercurrent to drive current 1, and then the process proceeds to step 360,
Set the undercurrent to 0.

Conversely, if a negative determination is made in step 340, the process proceeds to step 370 to set the drive current to the upper limit value C, and then proceeds to step 380, where the shortage set as the shortage current in the process previously performed is performed. Upper limit C for current
The difference between the driving current 1 and the driving current 1 is set.

Then, the drive current set in the subsequent step 390 is output. This drive current is output to the brake control actuator 3 through the drive circuit unit 7.

The undercurrent auxiliary control will be described with reference to each waveform shown in FIG. In addition, FIG.
FIG. 5 shows an example of a waveform of a driving current 1 (a required instruction current), an actual instruction current waveform, and a braking torque waveform.

As shown at time t1 in FIG. 10A, when the drive current 1 exceeds the upper limit C, the drive current that becomes the actual instruction current becomes equal to the upper limit C as shown in FIG. Is done. Then, the portion of the drive current 1 exceeding the upper limit value C is regarded as an insufficient current.

When the drive current 1 falls below the upper limit C as shown at time t2 in FIG.
As shown in (b), the value obtained by adding the insufficient current to the drive current 1 is defined as the drive current, and the difference between the drive current upper limit C and the drive current 1 is defined as the undercurrent. And FIG.
As indicated by the hatched portion in FIG. 0 (b), when the area of the drive current 1 exceeding the upper limit value C matches the area of the drive current 1 plus the insufficient current. , The undercurrent becomes 0, and the addition of the undercurrent to the drive current 1 is stopped.

Therefore, if the undercurrent supplementary control is not performed, there is a possibility that a time delay of the braking torque as shown by a dotted line in FIG. By performing the undercurrent auxiliary control as in the present embodiment, the time delay of the braking torque can be eliminated as shown by the solid line in FIG. 10C, and the overshoot caused by it can be suppressed.

(Fifth Embodiment) Even if the various compensation controls shown in the first to fourth embodiments are performed, the final command current is too large to be able to output and a time delay occurs to cause an overshoot. Although this may occur, in the present embodiment, compensation for such a case is performed.

FIG. 11 shows a block configuration of a vehicle brake device according to this embodiment. The vehicle brake device according to the present embodiment is different from the block configuration shown in the third embodiment in that the compensation current adding unit shown in FIG. 8 is used as a first compensation current adding unit. The difference is that the second compensation current adder 14 is provided, but the other components are the same. Therefore, the same components are denoted by the same reference numerals and description thereof is omitted.

The second compensation current calculating section 13 assumes an estimation model adapted to the characteristics of the brake driving actuator 3, and estimates a braking torque (limit braking torque) and a motor rotational angular speed actually obtained from this model. At the same time, the time when overshoot occurs is estimated based on the difference between the estimated value of the braking torque and the target braking torque, and unnecessary inertia is calculated due to the difference between the target motor rotational angular velocity and the estimated value of the motor rotational angular velocity at that time. A moment is obtained, and a current value for canceling the moment is calculated.

The second compensation current adder 14 cancels the unnecessary moment of inertia calculated by the second compensation current calculator 13 with respect to the drive current (instruction current) output by the drive current calculator 6. The compensation current is added.

Next, the control executed by the vehicle brake system according to the present embodiment will be described. FIG. 12 shows a flowchart of the control executed by the vehicle brake device in the present embodiment. This flowchart is inserted between step 300 and step 310 shown in FIG.
FIG. 13 shows an instruction current waveform, an assumed braking torque waveform, a motor rotation angular velocity waveform, a compensation current 2 waveform, a driving current waveform, and an actual braking torque waveform as waveforms related to each process in FIG. Will be described with reference to these drawings.

When the brake pedal is depressed, an instruction current is set according to the depressed state of the brake pedal at that time, and a target motor rotation angular velocity corresponding to the instruction current is calculated. Thus, for example, an instruction current as shown in FIG. 13A is set, and a target motor rotation angular velocity as shown in FIG. 13C is calculated. These processes are the same as steps 100 to 130 and 190 shown in FIG.

Then, the processing shown in FIG. 12 is performed. First, in step 400, a braking torque actually obtained is estimated based on the above-described estimation model. The estimated braking torque has, for example, a waveform as indicated by a dotted line in FIG. In step 410, the actually obtained motor rotational angular velocity is estimated again based on the estimation model. The estimated motor rotational angular velocity has, for example, a waveform as indicated by a dotted line in FIG.

Next, at step 420, a target braking torque corresponding to the set command current is calculated. This target braking torque has a waveform as shown by the solid line in FIG. Thereafter, in step 430, an error in the braking torque is calculated from the difference between the target braking torque and the estimated value of the braking torque.

Then, in step 440, it is determined whether or not the sign of the current torque error has been inverted from the previous value.
That is, since it is considered that an overshoot occurs at a point where the sign of the torque error is inverted (a point where the target braking torque and the estimated value of the braking torque intersect), this point is specified.

If an affirmative determination is made in step 440,
Proceeding to step 450, a constant D is set in the timer T3, and then proceeding to step 460. Then, in step 460, after calculating the speed error of the motor rotation angle from the difference between the target motor rotation angular speed and the estimated value of the motor rotation angular speed, the process proceeds to step 470, where the compensation current 2 is calculated based on the speed error of the motor rotation angle. Calculate. This compensation current 2 is as shown in FIG.
Are output until a predetermined period elapses from a point where an overshoot can occur with a negative pulse current as shown in FIG. Thereafter, the process proceeds to step 480, where a value obtained by adding the negative compensation current 2 to the driving current 1 is set as the driving current 1. As a result, as shown in FIG. 13E, the drive current 1 has a reduced waveform at a point where an overshoot may occur. This addition process is performed by the second compensation current calculation unit 13.

On the other hand, if a negative determination is made in step 440, the flow advances to step 490, in which the timer T3 is decremented, and the flow advances to step 500. And step 500
It is determined whether or not the timer T3 is 0. If a negative determination is made, the process proceeds to step 480 to perform the above-described processing. Conversely, if a positive determination is made, the process ends.

After that, based on the set drive current 1, the processing after step 310 shown in FIG. 9 is performed, and then the final command current is output to the brake drive actuator 3 through the drive circuit section 7. Is done.

As described above, a point at which overshooting is possible is specified by the estimation model, and the driving current 1 is reduced at this point.
As shown in FIG. 3 (f), even when the braking torque cannot be obtained according to the command current, the overshoot can be reduced.

(Sixth Embodiment) In the present embodiment, in addition to the first embodiment, hysteresis compensation is performed as one of friction compensation. Since the basic configuration of the vehicle brake device is the same as that of the first embodiment, only the details of the hysteresis compensation will be described here.

The brake driving actuator 3 shown in FIG. 1 has a friction loss or the like in a speed reducer or the like provided therein, and the output with respect to the input to the brake driving actuator 3 has a hysteresis as shown in FIG. Expressed in a relationship.

This embodiment compensates for the loss corresponding to the hysteresis. For example, as shown in FIG.
If the command current to be input to the brake driving actuator 3 is indicated by a broken line, when the command current is increasing, a value obtained by adding a compensation current so as to add a loss due to hysteresis is referred to as a post-compensation command current. I do. When the command current is in the maintenance state, the command current is directly used as the post-compensation command current. When the command current is falling, a value obtained by subtracting the compensation current so as to eliminate the excess due to the hysteresis is used as the post-compensation command current.

When such a command current compensation is performed, the output with respect to the input to the brake driving actuator 3 substantially has a relationship as shown in FIG. 16, and the hysteresis can be compensated.

Based on such a control theory, specifically,
The hysteresis compensation control executed by the vehicle brake device according to the present embodiment will be described. FIG. 17 shows a flowchart of the hysteresis compensation control, which will be described with reference to FIG. This hysteresis compensation control is performed as a part of the processing of the damping and friction correction current correction calculation in step 150 in FIG. 3, and is one of the instruction current compensations.

First, at step 510, an instruction current is input. Specifically, the command current obtained in step 120 of FIG. 3 is input. And step 52
The differential value of the instruction current input at 0 is calculated, and the differential value of the instruction current calculated at step 530 is positive (>
0) is determined. Accordingly, it is determined whether or not the command current is increasing. If the determination is affirmative, the process proceeds to step 540, in which the command current is obtained by adding a hysteresis loss, specifically, the command current is increased by one or more. A value multiplied by a positive number (for example, 1.2 times) is set as a post-compensation instruction current.

On the other hand, if a negative determination is made in step 530, the process proceeds to step 550, in which it is determined whether the calculated differential value of the indicated current is negative (<0). Accordingly, it is determined whether or not the command current is decreasing. If the result of the determination is affirmative, the process proceeds to step 560, where the command current is obtained by subtracting a surplus of hysteresis from the command current.
A value multiplied by the following positive number (for example, 0.8 times) is defined as a post-compensation instruction current. If a negative determination is made in step 550, it means that the command current is not increasing or decreasing and is in the maintenance state, and is thus used as the post-compensation command current without changing the command current.

Then, in step 570, the calculated corrected instruction current is output. When the compensation based on the damping / friction compensation current, the inertia compensation current, or the like as described in the first embodiment is performed, the compensation after the compensation current addition calculation shown in step 180 of FIG. 3 is further performed. It is output as the post-compensation instruction current.

As described above, the hysteresis compensation control can be performed based on whether the command current is rising, falling, or in the maintenance state, and the deviation of the command current due to the loss of the hysteresis is compensated. can do.

(Seventh Embodiment) In the case of open control, if a command current exceeding the capability of the brake driving actuator 3 is applied, control may be impossible. For example, as shown in the timing chart of FIG. 18, when a high-response command current exceeding the capacity of the brake driving actuator 3 is applied, the actual output is reduced due to a back electromotive force or the like. The value does not catch up with the command current, and rises with a gentler slope than the command current. Then, since the brake starts to be applied before the actual output value sufficiently rises, the actual output value further decreases and control becomes impossible.

The present embodiment is to avoid the above-mentioned control failure. Specifically, as shown in FIG.
A slope limit is provided in advance so that the slope of the command current does not exceed the capability of the brake driving actuator 3 so that the slope of the command current matches the actual output value. By doing so, the above-described inability to control can be avoided. Note that the inclination limit here is not limited to one that is constant in all situations, includes one that is appropriately changed, and one that is changed in multiple stages.

Further, here, the inclination of the command current is limited in advance, but it is not always necessary to do so. For example, as shown in FIG. 20A, when the actual output value cannot keep up with the initially scheduled instruction current, the instruction current is compared with the actual output value, and based on the result, As shown in FIG. 20B, the slope of the command current may be limited. In this case, for example, the relationship between the command current and the actual output value and the limit of the slope of the command current is obtained in advance and mapped, and the slope limit of the command current can be obtained from the comparison result based on the map.

Further, inertia compensation may be prohibited. That is, in the above-described first embodiment, the influence of the inertial force of the actuator is taken into account, and inertia compensation is performed when the command current shifts from rising to a steady state (FIGS. 4C and 4D). )reference). However, since the inertia compensation at this time is a compensation that causes the command current to drop, if such compensation is performed when the actual output value cannot catch up with the command current as shown in the present embodiment, The actual output value drops more. For this reason, by inhibiting inertial compensation, it is possible to prevent the actual output value from dropping.

(Eighth Embodiment) FIG. 21 shows a block configuration of a vehicle brake device to which an eighth embodiment of the present invention is applied. The vehicle brake device according to the present embodiment is obtained by adding feedback compensation to the third embodiment. Therefore, only the configuration different from the third embodiment will be described.

As shown in FIG. 21, the vehicle brake device according to the present embodiment includes an error calculator 15 and a feedback calculator 16. The error calculation unit 15
An error between the braking torque assumed from the calculation result of the command current calculation unit 4 and the actual braking torque is calculated based on the output value of the brake driving actuator 3, for example, the actual braking torque. The actual detection of the braking torque is performed based on, for example, detection of a pressing force by a motor or oil pressure (for example, master cylinder pressure). Further, the feedback control calculation unit 16 performs compensation based on the calculation result of the error calculation unit 15 so as to eliminate the error.

As described above, feedback compensation can be provided, and more optimal control can be performed. If there is a non-linear term such as hysteresis or pre-current, simple feedback compensation will
Although response delay and overshoot occur, optimal control that can further suppress response delay and overshoot can be performed by combining with feedforward compensation and compensating for a nonlinear term by feedforward compensation.

Further, when performing feedback compensation in this way, if a sensor for detecting the output value of the brake driving actuator 3 fails, accurate feedback control cannot be performed. Therefore, in such a case,
The following control may be performed.

FIG. 22 shows a flowchart of this control. As shown in this figure, first, in step 610,
A determination is made as to whether the sensor has failed. The failure of the sensor is performed, for example, based on a diagnostic signal based on a self-diagnosis function of the sensor, that is, a failure signal caused by output of a potential outside a potential range used during normal inspection.

Thus, if a negative determination is made, step 6
Proceeding to 20 to 640, a feedback operation, a compensation current addition operation, and a pre-current drive operation are performed, and a drive current operation is performed in step 650. Conversely, if an affirmative determination is made, the process proceeds to steps 660 to 680, where the feedback calculation is prohibited and the compensation current addition calculation and the pre-current drive calculation are performed.
At step 650, drive current calculation is performed.

As described above, when the sensor fails, the feedback control is prohibited, and the feedforward compensation is performed, so that the control can be stably performed even in the case of a failure. It should be noted that, with the prohibition of the feedback calculation in step 660, the compensation gain of the compensation current addition calculation can be changed in step 670, so that the compensation for eliminating the feedback compensation can be expected.

(Ninth Embodiment) In each of the above embodiments, the hysteresis of the brake driving actuator 3 is determined.
Since the pressurization gradient and the like change due to aging, environment, and the like, it is possible to change the feedforward control constant to an optimum value in consideration of these.

For example, the brake driving actuator 3
The feedforward constant may be varied based on predetermined parameters such as the temperature, supply voltage, operation history, previous operation time, and interval from the previous operation. Also, for example, the amount of pressurization by the motor, the motor current, the number of motor rotations,
The difference between the target output value and the actual output value of the stroke amount of the brake pad or the like driven by the motor may be determined, and the feedforward constant may be varied based on the difference.

Further, when performing feedback compensation as in the eighth embodiment, the feedforward constant can be varied based on the result.

For example, as shown in FIG. 23A, the command current and the brake driving actuator 3
In the case where the initial map of the output value of (1) (the map before the change) is the one shown by the broken line in the figure, the command current and the output value after the feedback compensation are those shown by the solid line in the figure. For example, since the above change is considered to appear in the feedback compensation, the map is updated to the command current and the output value after the feedback compensation as shown in FIG.

As shown in FIG. 24A, the initial map (the map before the change) of the command current and the corresponding output value of the brake driving actuator 3 when the hysteresis compensation is performed is indicated by a broken line in the figure. If the command current and the output value after the feedback compensation are those shown by the solid lines in the figure in the case shown in FIG. 24, as shown in FIG. Update map with current and output values.

In this way, it is possible to perform an optimal feedforward control in consideration of the aging of the brake driving actuator 3 such as the hysteresis and the pressure gradient and the change due to the environment and the like.

(Other Embodiments) The first, second, and fourth embodiments
In the embodiment, the instruction current compensation control, the pre-current calculation control, and the undercurrent auxiliary control are described separately, but all of them may be performed in combination. In this case, step 200 shown in FIG. 6 is connected to step 190 shown in FIG. 3, and step 290 shown in FIG.
00 should be connected.

As shown in FIG. 25, a master cylinder pressure is generated by driving a master piston provided in the master cylinder 21 by a motor 20, and connected to the master cylinder 21 based on the generated master cylinder pressure. The present invention can also be applied to an electric brake device in which a hydraulic circuit that drives the caliper 22 and pressurizes the brake pad 23 to generate a braking force by friction with the brake disk 24 is interposed. In this case, the present invention can be applied to eliminate the dead zone in the master cylinder 21.

Further, as shown in FIG. 26, a motor 20 and a hydraulic piston 25 are provided for each wheel.
The present invention also relates to an electric brake device in which a hydraulic circuit is provided to generate hydraulic pressure in the hydraulic piston 25 by driving the hydraulic piston 25 and drive the caliper 22 connected to each hydraulic piston 25 based on the generated hydraulic pressure. Can be applied. In this case, the present invention can be applied to eliminate the dead zone of the hydraulic piston 25.

Although nothing is described in the hydraulic circuit for the configuration shown in FIG. 25, of course, ABS
It is also possible to provide an actuator. However, in such a configuration, when the ABS control is performed, the relationship between the stroke amount of the master piston due to the above-described inertia compensation and the like and the master cylinder pressure actually generated varies, and the inertia compensation is performed. In some cases, an error occurs, and the feedback also causes resonance, resulting in loss of control. For this reason, when the ABS control is performed, at least one of the feedforward compensation and the feedback compensation is stopped, or control for varying at least one of the control gains is performed.

FIG. 27 shows a flowchart of this control. As shown in this figure, first, at step 710, it is determined whether or not the ABS control is being performed. This judgment is
This is performed by confirming whether or not a flag that is set when the slip ratio obtained from the wheel speed signal or the like becomes equal to or more than a predetermined value is set. If a negative determination is made, the process proceeds to step 720, and the motor drive control constant is kept at the normal value A. If a negative determination is made, the process proceeds to step 730, where the motor drive control constant is changed to B for ABS control. . Then, in step 740, step 72
After performing the drive current calculation based on the motor drive control constants determined in 0 and 730, in step 750,
The calculated drive current is output. In this way, A
Stable control can be performed without being affected by the BS control.

[Brief description of the drawings]

FIG. 1 is a diagram showing a block configuration of a vehicle brake device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a control theory of a command current compensation control.

FIG. 3 is a flowchart of a command current compensation control.

4 is a diagram showing various waveforms related to the command current compensation control shown in FIG.

FIG. 5 is a diagram showing a block configuration of a vehicle brake device according to a second embodiment of the present invention.

FIG. 6 is a flowchart of a pre-current calculation control.

7 is a diagram showing various waveforms related to the pre-current calculation control shown in FIG.

FIG. 8 is a diagram showing a block configuration of a vehicle brake device according to a third embodiment of the present invention.

FIG. 9 is a flowchart of undercurrent auxiliary control according to a fourth embodiment of the present invention.

10 is a diagram showing various waveforms related to the undercurrent auxiliary control shown in FIG. 9;

FIG. 11 is a diagram showing a block configuration of a vehicle brake device according to a fifth embodiment of the present invention.

FIG. 12 is a flowchart of control performed by the vehicle brake device shown in FIG. 11;

13 is a diagram showing various waveforms related to the control shown in FIG.

FIG. 14 is a diagram illustrating a relationship between an input and an output when there is hysteresis.

FIG. 15 is a diagram illustrating a relationship between an instruction current and an instruction current after correction when hysteresis compensation is performed.

FIG. 16 is a diagram illustrating a relationship between an input and an output when hysteresis compensation is performed.

FIG. 17 is a flowchart of hysteresis compensation control.

FIG. 18 is a timing chart showing a relationship between a command current and an actual output value.

FIG. 19 is a timing chart showing a relationship between a command current and an actual output value.

FIG. 20 is a timing chart in a case where a gradient of a command current is limited.

FIG. 21 is a diagram showing a block configuration of a vehicle brake device according to an eighth embodiment of the present invention.

FIG. 22 is a flowchart of feedback compensation fail control.

FIGS. 23A and 23B are diagrams illustrating an indicated current and an output value in a case where feedback compensation is performed and in a case where feedback compensation is not performed, and FIG. 23B illustrates a case where an indicated current map is updated based on feedback compensation; FIG. 4 is a diagram illustrating an instruction current and an output value.

FIG. 24A is a diagram illustrating an instruction current and an output value in a case where feedback compensation is performed and in a case where feedback compensation is not performed. FIG. 24B is a diagram illustrating a case where a map of the instruction current is updated based on feedback compensation. FIG. 4 is a diagram illustrating an instruction current and an output value.

FIG. 25 is a view showing a schematic configuration of a vehicle brake device shown in another embodiment.

FIG. 26 is a view showing a schematic configuration of a vehicle brake device shown in another embodiment.

FIG. 27 is a flowchart of motor drive control constant setting control when performing ABS control.

FIG. 28 is a diagram illustrating a time delay and an overshoot caused by characteristics of a brake control actuator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Tread force sensor, 2 ... ECU, 3 ... Brake drive actuator, 4 ... Instruction current calculation part, 5 ... Compensation current addition part, 6 ... Drive current calculation part, 7 ... Drive circuit part.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuzo Imoto 1-1-1, Showa-cho, Kariya-shi, Aichi Pref. F-term (reference) 3D046 BB03 EE01 HH02

Claims (13)

[Claims] 1. A brake device for a vehicle configured to generate a braking torque by driving a brake drive actuator (3) when a brake pedal is depressed, wherein the brake pedal is depressed. And a compensation current adding means (5) for adding a compensation current to the command current when the command current changes, wherein the compensation current is added. The brake device for a vehicle, wherein the brake driving actuator is driven based on the command current. 2. A method according to claim 1, wherein a current corresponding to a time delay of the braking torque generated due to an inertia moment of the brake driving actuator is added to the command current when the command current changes. The vehicle brake device according to claim 1, wherein the vehicle brake device is provided. 3. The method according to claim 1, wherein a current corresponding to a time delay of the braking torque generated due to at least one of a damping loss and a frictional loss of the brake driving actuator is added to the command current as the compensation current. The vehicle brake device according to claim 1, wherein the vehicle brake device is provided. 4. A brake device for a vehicle configured to generate a braking torque by driving a brake drive actuator (3) when a brake pedal is depressed, wherein the brake pedal is depressed. And a compensation current adding means (5) for adding a compensation current to the command current when the command current rises, wherein the compensation current is added. The brake device for a vehicle, wherein the brake driving actuator is driven based on the command current. 5. A method according to claim 1, wherein a current corresponding to a time delay of the braking torque generated due to an inertia moment of the brake driving actuator is added to the command current when the command current rises. The vehicle brake device according to claim 4, wherein the vehicle brake device is provided. 6. A brake device for a vehicle configured to generate a braking torque by driving a brake driving actuator (3) when a brake pedal is depressed, wherein the brake pedal is depressed. Command current calculating means (4) for calculating a command current in accordance with the following; and compensation current adding means (5) for adding a compensation current to the command current when transitioning to a steady state after the command current rises. A brake device for driving the brake driving actuator based on the command current to which the compensation current is added. 7. A brake device for a vehicle configured to generate a braking force by driving a brake driving actuator (3) when a brake pedal is depressed, wherein the brake pedal is depressed. Command current calculating means (4) for calculating a command current according to the following; and compensation current adding means (5) for adding a compensation current to the command current after the command current rises and before transition to a steady state. ), Wherein the brake driving actuator is driven based on the command current to which the compensation current has been added. 8. A current corresponding to a time delay of the braking torque generated due to at least one of a damping loss and a friction loss of the brake driving actuator is added to the command current as the compensation current. The vehicle brake device according to claim 7, wherein the vehicle brake device is provided. 9. A vehicle brake device configured to generate a braking torque by driving a brake driving actuator (3) when a brake pedal is depressed, wherein the brake pedal is depressed. Command current calculating means (4) for calculating a command current according to the following; and brake pedal depression detecting means (1, 10) for determining whether or not the brake pedal is depressed
And a pre-current adding means (11) for sequentially adding a positive and a negative compensation current to the instruction current when it is detected that the brake pedal is depressed, wherein the compensation current is added. A brake device for a vehicle, wherein the brake drive actuator is driven based on the command current. 10. The pre-current adding means adds a negative and a positive compensation current to the command current in order when the depression of the brake pedal is stopped after the depression is performed. The vehicle brake device according to claim 9, wherein the vehicle brake device is provided. 11. When the command current to which the compensation current is added exceeds a predetermined upper limit (C), when the command current to which the compensation current is added falls below the upper limit, The vehicle according to any one of claims 1 to 10, further comprising an undercurrent assisting unit that adds an amount exceeding the upper limit to the instruction current to which the compensation current has been added. Brake equipment. 12. A brake device for a vehicle configured to generate a braking torque by driving a brake drive actuator (3) when a brake pedal is depressed, wherein the brake pedal is depressed. Command current calculating means (4) for calculating a command current according to the following; an estimating means for estimating a limit braking torque that can be generated by the brake driving actuator; and a command current calculated by the command current calculating means. Means for comparing the required target braking torque with the limit braking torque estimated by the estimating means, and identifying a point at which the sign of the difference between the limit braking torque and the target braking torque is inverted; At the point where is inverted, a compensation current adding means for adding a compensation current to the instruction current ( 4) and the vehicle brake system, characterized in that it comprises a. 13. The method according to claim 1, wherein when the command current is set to a value exceeding the capacity of the brake driving actuator, a slope of the command current is limited. A vehicle brake device according to any one of the preceding claims.