JP2002283985A - Braking controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a braking controller that does not give uncomfortable feeling to a driver in performing prebraking. SOLUTION: A degree of urgency is estimated based on at least one of a plurality of estimation indicators such as a return speed of an accelerator pedal, a foot rest depressing force, and an approaching state to an obstacle in front of a vehicle, and the higher the degree of urgency is, the larger a prebraking force is set to be. In estimating the degree of urgency, when only one estimation indicator is set, the set estimation indicator is used as an estimated degree of urgency of the degree-of-urgency estimating means, and when a plurality of estimation indicators are set, a complex estimation indicator generated from the plurality of estimation indicators is used as an estimated degree of urgency of the degree-of-urgency estimating means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake control device for performing preliminary braking before a driver enters a braking operation when the host vehicle approaches an obstacle in front of the host vehicle.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Application Publication No. 11-175898 discloses an apparatus for performing preliminary braking not based on a braking operation prior to a driver's braking operation based on a distance from an obstacle in front of the host vehicle. Further, in each of JP-A-8-80822 and JP-A-10-59150, when the speed at which the accelerator pedal operated by the driver is released is equal to or higher than a predetermined value, the brake pedal is subsequently depressed. An apparatus for performing preliminary braking for supplying braking fluid pressure to a wheel cylinder in advance assuming that the braking operation described above is performed is disclosed.

In these techniques, it is determined whether or not to perform preliminary braking prior to a braking operation based on the distance to an obstacle in front of the host vehicle and the accelerator operation of the driver. As an example, a technique using a biological reaction of a driver in an emergency is also disclosed. Examples of the biological reaction include a force acting in the axial direction of the steering (Japanese Patent Application Laid-Open
-24818), steering wheel gripping force (JP-A-11-286264), footrest treading force (JP-A-11-5528 and JP-A-11-255).
No. 087) and heart rate (JP-A-5-112158 and JP-A-11-286264) are disclosed.

[0004]

The distance to an obstacle in front of the vehicle, the operation of the accelerator pedal by the driver, and the biological response of the driver can be used as criteria for determining whether or not to perform preliminary braking. However, if the same level of preliminary braking force was generated uniformly based on these criteria,
There is a concern that the discomfort given to the driver may sometimes increase.

According to the present invention, in the braking control device for performing the preliminary braking independent of the braking operation of the driver, the preliminary braking force is changed according to the type of the criterion for determining whether or not to perform the preliminary braking. It is an object of the present invention to provide a braking control device that can solve the problem.

[0006]

Means for Solving the Problems To solve the above problems,
According to a first aspect of the present invention, there is provided a brake control device configured to generate a preliminary braking force independently of a driver's braking operation, and a preliminary brake generated by the preliminary braking device. Preliminary braking control means for controlling the power; acceleration operation means operated in accordance with the driver's intention to accelerate; acceleration operation change amount detection means for detecting an acceleration operation change amount of the acceleration operation means; A living body reaction detecting means for detecting the above living body reaction, an approaching state detecting means for detecting an approaching state to an obstacle in front of the vehicle, and an emergency operation change amount, a living body reaction, and an approaching state. An emergency evaluation means for evaluating the degree, and a preliminary braking force correction means for increasing the preliminary braking force controlled by the preliminary braking control means as the degree of emergency evaluated by the emergency evaluation means increases. In preparation That.

[0007] In the braking control device according to the second aspect, the urgency evaluation means includes a first evaluation unit that sets a first evaluation index from the acceleration operation change amount, and a second evaluation unit based on the biological reaction. A second evaluation unit that sets an evaluation index, and a third evaluation unit that sets a third evaluation index from the approach state,
When only one of the first, second, and third evaluation indices is set, the urgency level is set to the evaluation index. In addition to the evaluation urgency of the evaluation means, when a plurality of evaluation indexes are set among the first evaluation index, the second evaluation index, and the third evaluation index, the plurality of evaluation indexes are set. Is used as the evaluation urgency of the urgency evaluation means.

Further, in the braking control device according to claim 3, the urgency evaluation means performs an adding process on the plurality of evaluation indices to obtain the composite evaluation indices.

Further, in the braking control device according to claim 4, the urgency evaluation means performs a multiplication process on the plurality of evaluation indices to obtain the composite evaluation indices.

[0010] In the braking control device according to the fifth aspect, the urgency evaluation means sets the first evaluation index as an urgency higher than the second evaluation index and the third evaluation index. It is.

Further, in the braking control device according to claim 6, the urgency evaluation means sets the second evaluation index to be higher in urgency than the third evaluation index.

Further, in the braking control device according to claim 7, the urgency evaluation means is configured to generate a composite evaluation index obtained by combining the second evaluation index and the third evaluation index with the first evaluation index. This is equivalent to the evaluation index.

[0013] In the braking control device according to claim 8, the preliminary braking control means includes:
When it is determined that the host vehicle is approaching an obstacle in front of the vehicle, the start of the preliminary braking is determined.

Further, in the braking control device according to claim 9, the preliminary braking control means determines the start of the preliminary braking when the biological reaction is detected.

[0015] In the brake control device according to the tenth aspect, the preliminary braking control means may include: when the acceleration operation change amount is negative and the absolute value of the acceleration operation change amount is equal to or more than a predetermined value, The start of the preliminary braking is determined.

The braking control device according to the eleventh aspect further includes a relative distance detecting means for detecting a relative distance to an obstacle in front of the vehicle, and a host vehicle speed detecting means for detecting a speed of the host vehicle. The approach state detection means detects the approach state using the relative distance and the speed of the host vehicle.

Further, in the braking control device according to the twelfth aspect, the preliminary braking force correction means does not update the preliminary braking force when the preliminary braking force has a value smaller than the previous braking force. It is.

[0018]

According to the first aspect of the present invention, at least one of the acceleration operation change amount, the biological reaction, and the approach state is selected.
First, the emergency level is evaluated, and the larger the emergency level is, the larger the preliminary braking force is. Therefore, it is possible to change the preliminary braking force according to the evaluated emergency level, and the driver may feel uncomfortable. Can be lowered.

According to the second aspect of the present invention, any one of the first evaluation index based on the amount of change in the acceleration operation, the second evaluation index based on the biological reaction, and the third evaluation index based on the approaching state. If only one is set, the urgency of the urgency evaluation means is set based on the evaluation index, and if more than one evaluation index is set, Set the urgency. Here, when a plurality of evaluation indices are combined, they may be added as in the configuration of the third aspect, or may be multiplied as in the configuration of the fourth aspect. As a result, it is possible to increase the certainty of the evaluation of the degree of urgency, and it is possible to further reduce the sense of discomfort given to the driver.

According to the fifth aspect of the present invention, when setting the first evaluation index, by setting the first evaluation index to be more urgent than the second and third evaluation indexes, there is a possibility that the driver enters the braking operation. It is possible to further increase the certainty of the evaluation of the urgency in consideration of the size of the emergency.

According to the configuration of claim 6, when setting the second evaluation index, the degree of urgency of the driver to enter the braking operation is set by setting the second evaluation index to be more urgent than the third evaluation index. In consideration of the above, it is possible to further increase the certainty of the evaluation of the urgency.

According to the configuration of claim 7, the composite evaluation index obtained by combining the second evaluation index and the third evaluation index is equivalent to the first evaluation index, so that the driver can perform braking operation. The certainty of the evaluation of the urgency can be further increased in consideration of the possibility of entry.

According to the eighth aspect of the present invention, the start of the preliminary braking is determined based on the approach state to the obstacle in front of the vehicle, so that the braking operation of the driver can be expected.

According to the configuration of the ninth aspect, the start of the preliminary braking is determined based on the biological reaction, so that the braking operation of the driver can be more reliably predicted.

According to the tenth aspect, the start of the preliminary braking is determined when the amount of change in the acceleration operation is negative and the absolute value of the amount of change in the acceleration operation is equal to or greater than the predetermined value, thereby driving the vehicle. It is possible to more reliably anticipate the braking operation of the user.

According to the eleventh aspect, the approach state is detected based on the relative speed with respect to the obstacle ahead of the vehicle and the speed of the host vehicle, so that the approach state with the obstacle is detected more reliably. It is possible.

According to the twelfth aspect of the present invention, when the preliminary braking force is smaller than the previous value, the preliminary braking force is not updated and the previous value is used. Even when the power is changed, by maintaining this at a high value, the effect of the preliminary braking control can be sufficiently exhibited, and the fluctuation of the preliminary braking force can be suppressed.

[0028]

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

(First Embodiment) FIG. 1 is a system configuration diagram showing a first embodiment of the present invention.
L and 21FR are front wheels of the own vehicle, 21RL and 21RR are rear wheels, and these front wheels 21FL and 21FR and rear wheel 2 are provided.
1RL and 21RR have brake actuators 22 respectively.
FL, 22FR and 22RL, 22RR are mounted. Each of the brake actuators 22FL to 22RR is configured to generate a braking force according to a fluid pressure supplied from a master cylinder 25 described later.

Reference numeral 23 denotes a brake pedal, which is connected to the electronic negative pressure booster 24 and the master cylinder 25 via the operating rod 6. Brake pedal 2
3 is provided with a brake switch 26 for detecting the depression. The electronic negative pressure booster 24 will be described later in detail. A pipe 17a connects between the output side of the master cylinder 25 and the brake actuators 22FL and 22FR through the brake actuators 22RL and 22FR.
R and two pressure sensors 32 and 33 for detecting fluid pressures Pw1 and Pw2 for detecting the braking force generated in the vehicle are connected to the pipes 17a and 17b, respectively. It is arranged. Fluid pressures Pw1, detected by these two pressure sensors 32, 33,
Although Pw2 should originally detect the same value, even if a detection error occurs in one of them, each of the pipes 17 is prepared for the arithmetic processing described later in order to secure controllability of the system.
a, 17b.

An accelerator pedal 27 is provided with an accelerator stroke sensor 28 for detecting the accelerator opening θ from the stroke of the accelerator pedal. Here, the accelerator opening θ
Becomes larger as the driver steps on the accelerator pedal 27. Reference numeral 35 denotes a footrest, which is a footrest treading force sensor 3 for detecting a treading force of the footrest 35.
6 are provided.

As shown in FIG. 2, the above-mentioned electronic negative pressure booster 24 has a structure in which the variable pressure chamber 1 and the negative pressure chamber 2 are connected to the diaphragm 14.
When the brake is not operated, the variable pressure chamber 1 is in a negative pressure state determined by the engine negative pressure, is in a pressure balanced state with the negative pressure chamber 2, and when the brake is operated, the atmosphere is introduced, and the negative pressure chamber 2 Of the master cylinder 2
The load boosted to 5 is transmitted. The negative pressure chamber 2 is always maintained at a predetermined negative pressure during engine start.

A shaft cylinder 17 is fixed to the center of the diaphragm 14, and a communication passage 11 for communicating the negative pressure chamber 2 and the variable pressure chamber 1 is formed in the shaft cylinder 17. A vacuum valve 3 is disposed in the section, and the vacuum valve 3 is closed when the brake pedal 23 is stroked by the driver or when the solenoid valve 5 is excited, and the negative pressure chamber 2 and the variable pressure chamber 1 are closed.
Cuts off communication with the

An atmosphere valve 4 is provided between the transformation chamber 1 and the atmosphere.
The atmospheric valve 4 operates in cooperation with a valve element 12 formed on a sliding cylinder 5b, which will be described later, and when the brake pedal 23 is stroked by the driver or when the electromagnetic valve 5
Is opened when excited, and the atmosphere is introduced into the transformation chamber 1.

The solenoid valve 5 is composed of a solenoid 5a disposed on the inner peripheral portion of the shaft cylinder 17 and a sliding cylinder 5b slidably disposed facing the solenoid 5a. An engaging portion 18 for operating the above-described vacuum valve 3 and atmospheric valve 4 is formed on the right end side of the moving cylinder 5b.

The sliding cylinder 5b is urged rightward by a return spring 15 disposed in the negative pressure chamber 2 and has an operating rod 6 inside.
The tip of the operating rod 6 is connected to the master cylinder 25 via the push rod 8.

Return springs 13a and 13b are provided between the operating rod 6 and the shaft cylinder 17 and between the vacuum valve 3 and the atmospheric valve 4, respectively. Is provided with a return spring 16.

Referring back to FIG. 1, reference numeral 30 denotes a vehicle speed sensor which detects the own vehicle speed Vm from the output shaft rotation speed of the transmission. 31
Is an inter-vehicle distance sensor, which detects a relative distance L to an obstacle in front of the vehicle by a laser radar or a millimeter-wave radar disposed at the front of the vehicle. Reference numeral 34 denotes a changeover switch 34 for automatically selecting whether or not to perform preliminary braking.

Reference numeral 29 denotes a control device, which is a brake switch.
Switch 26 from the switch 26_BRK,accelerator
The accelerator opening θ from the stroke sensor 28 and the pressure sensor
The braking fluid pressures Pw1, Pw2 from the
Speed Vm from the sensor 30 and the phase
Distance L, switch signal Sw from changeover switch 34,
Footrest pedal force signal from footrest pedal force sensor 36
No. FT is input, and preliminary braking control is performed based on these signals.
Or not, and the preliminary braking fluid pressure target value P _PBThe set
Then, the solenoid valve 5 of the electronic negative pressure booster 24 is controlled.
A preliminary braking control process is performed.

Here, it is determined whether or not the preliminary braking control is to be performed, based on whether the return speed of the accelerator pedal 27 is equal to or higher than a predetermined value, whether the biological response of the driver is equal to or higher than a predetermined value, the vehicle speed Vm and the relative distance. The processing is executed based on the fact that the state of approach to the obstacle ahead of the vehicle to be obtained is equal to or greater than a predetermined value.

The value of the target value P _PB of the preliminary braking fluid pressure is
When the return speed of the accelerator pedal 27 is equal to or higher than a predetermined value (hereinafter, referred to as a first evaluation index), the biological response of the driver is equal to or higher than a predetermined value (hereinafter, referred to as a second evaluation index), and the vehicle speed Vm
And an approach state to an obstacle ahead of the vehicle obtained from the relative distance is equal to or greater than a predetermined value (hereinafter, referred to as a third evaluation index)
Based on a plurality of evaluation indices, such as the above, it is set based on the following concept. As described above, these first to third evaluation indices are also criteria for determining whether or not to perform the preliminary braking control. In other words, the first to third evaluation indices indicate the possibility that the driver enters the braking operation, so to speak, an emergency. It can be called a degree indicator.

(Weighting for each evaluation index) When the driver finds an obstacle ahead, the driver's actions are considered to be in the order of recognition of the obstacle → reaction → operation as shown in FIG. . That is, the operation of returning the accelerator pedal 27 by the driver is often performed prior to the braking operation, whereas the biological reaction of the driver when an obstacle is found ahead is more than the operation of the driver returning the accelerator pedal 27. Is generated beforehand, but it is considered that the possibility of actually shifting to the braking operation at this time is not necessarily higher than the operation of returning the accelerator pedal 27 described above. From this, when the first evaluation index related to the operation of the driver returning the accelerator pedal 27 occurs, compared to when the second evaluation index related to the biological reaction of the driver occurs, It is considered that there is a high possibility that the braking operation will be performed. Also, when the second evaluation index occurs, there is a high possibility of leading to the braking operation as compared with the case where no other evaluation index has occurred or the case where the third evaluation index not related to the biological reaction has occurred. it is conceivable that. For this reason, in the present embodiment, the weights of the evaluation indices are set so that the first evaluation index> the second evaluation index> the third evaluation index. This will be described specifically in the flowchart of FIG.

(Composite evaluation index) The first to third evaluation indices can be evaluation indices singly, but if there are a plurality of evaluation indices, there is a possibility that the driver will enter a braking operation (an index of urgency). ) Is even larger, and it is possible to increase the certainty. For example, despite the fact that the degree of urgency is not actually large, the driver happens to operate the accelerator pedal 27 so that the first evaluation index is generated, or the biological reaction such that the second evaluation index is generated. May occur, or the inter-vehicle distance sensor 31 may detect an object that does not originally interfere with the own vehicle while traveling on a curved road. In such a case, the urgency is set to be greater as the number of evaluation indices is larger. This will be described specifically in the flowchart of FIG.

Next, the arithmetic processing for the preliminary braking control performed by the controller 29 will be described with reference to the flowcharts of FIGS.

This arithmetic processing is performed for a predetermined time ΔT (for example, 1
0 msec.) Is executed as a timer interrupt process. It should be noted that although this flowchart does not particularly include a step for communication, information obtained by calculation is stored as needed, and the stored information is read as needed.

First, in step S1, the outputs of the sensors and switches are read in accordance with the individual arithmetic processing performed in step S1.

Next, the process proceeds to step S2, in which the vehicle speed Vm is read from the information read in step S1.

Next, the process proceeds to step S3, at which the relative distance L to the obstacle ahead is read from the information read at step S1.

Then, the process goes to step S4 to calculate the relative distance change speed dL / dt from the time differential value of the relative distance L.

Next, the process proceeds to step S5, where the target deceleration Gx ^{* for} avoiding contact with the front obstacle is obtained by using the own vehicle speed Vm, the relative distance L to the front obstacle, and the relative distance change speed dL / dt ^. Is calculated according to the following equation.

Gx ^* = {Vm ² − (Vm−dL / dt) ² } / 2L (1) Next, the process proceeds to step S 6 to determine whether or not the driver is depressing the brake pedal 23. The brake switch 26
Brake switch signal S _BRK from is judged by whether it is showing the ON state "1", the brake switch signal S _{BR K} is in the ON state (has stepped on the brake pedal 23) step. If S12 Otherwise, to step S7.

In step S7, it is determined whether or not the driver is depressing the accelerator pedal 27, whether or not the accelerator opening θ detected by the accelerator stroke sensor 28 is equal to or greater than a predetermined accelerator closing predetermined value θ _OFF . If the accelerator opening θ is equal to or greater than the predetermined accelerator closing value θ _OFF (the accelerator pedal 27 is depressed), the process proceeds to step S12, and if not, the process proceeds to step S12.
Move to 8.

In step S8, it is determined whether or not the driver is returning the accelerator pedal 27 at a speed higher than a predetermined speed by determining whether the accelerator opening change dθ / dθ calculated from the accelerator opening θ detected by the accelerator stroke sensor 28. It is determined whether dt is negative and whether its absolute value exceeds a predetermined value α (α> 0). dθ / dt
If <0 and | dθ / dt |> α, it is determined that the preliminary braking control is necessary, and the process proceeds to step S20. If not, the process proceeds to step S9. That is, this step is a criterion for determining whether or not to perform the preliminary braking control, and indicates the above-described first evaluation index.

[0054] In step S9, whether or not there is a predetermined or more biological reaction of the driver, the footrest determines footrest depression force signal FT is by whether more than a predetermined value FT ₀ from depression sensor 36 (where FT ₀ > 0). F
When a T> FT _0, it is determined that it is necessary to pre-braking control proceeds to step S15, but if not, it proceeds to step S10. That is, this step is a criterion for determining whether or not to perform the preliminary braking control,
9 shows the above-described second evaluation index.

In step S10, the calculation in step S5 is performed.
Absolute value of the target deceleration for avoiding contact with the obstacle ahead
| Gx^*| Is a predetermined target deceleration predetermined value Gx₀ ^*
(Numerical value of the target deceleration predetermined value (-
Gx₀ ^*) The following is determined). The target deceleration
Absolute value of degree | Gx₀| Is the target deceleration predetermined value Gx₀ ^*Above
In some cases, the approach to obstacles ahead of the vehicle
The preliminary braking control is necessary.
If the process moves to step S13 based on the
In this case, the process proceeds to step S11. That is, this step
It is a criterion for determining whether or not to perform preliminary braking control.
The following shows the third evaluation index described above.

[0056] In step S11, the preliminary brake fluid pressure target value P _PB at the present time is equal to or greater than or equal 0MPa, updates the preliminary brake fluid pressure target value P _PB at the moment when it is more 0MPa Without proceeding to step S30,
If not, the flow shifts to step S12 to set the preliminary braking fluid pressure target value P _PB to 0 MPa and then returns. This is to maintain the preliminary braking control when the preliminary braking control was performed in the previous process.

On the other hand, if the determination in step S10 is Yes, the process proceeds to step S13, where it is determined whether or not the current preliminary braking fluid pressure target value P _PB is 0.1 MPa or more. If the pressure is equal to or greater than 1 MPa, the process proceeds to step S30 without updating the current preliminary braking fluid pressure target value P _PB , and if not, to step S14.
The program proceeds to step S30 to set the preliminary braking fluid pressure target value P _PB to 0.1 MPa, and then proceeds to step S30. This is to maintain the preliminary braking control in the previous process.

On the other hand, the judgment in the step S9 is Y
If the answer is es, the process moves to step S15, and the absolute value of the target deceleration | Gx
It is determined whether ^* | is equal to or greater than the predetermined target deceleration predetermined value Gx ₀ ^*. If Yes, the process proceeds to step S18; otherwise, the process proceeds to step S16.

In step S16, it is determined whether or not the current pre-brake fluid pressure target value P _PB is 0.2 MPa or more. If it is more than 0.2 MPa, the current pre-brake fluid pressure target value P _PB is determined. The process _proceeds to step S30 without updating P _PB , and otherwise, proceeds to step S17 to set the preliminary braking fluid pressure target value P _PB to 0.2 MPa, and then proceeds to step S30. This is to maintain the preliminary braking control in the previous process.

On the other hand, if the determination in step S15 is Yes, the process proceeds to step S18, where it is determined whether or not the current preliminary braking fluid pressure target value P _PB is 0.3 MPa or more. If the pressure is equal to or higher than 3 MPa, the process proceeds to step S30 without updating the current preparatory braking fluid pressure target value P _PB , otherwise, to step S19.
Then, the process proceeds to step S30, where the preliminary braking fluid pressure target value P _PB is set to 0.3 MPa. This is to maintain the preliminary braking control in the previous process.

On the other hand, the judgment in step S8 is Y
When became es proceeds to step S20, footrest depression force signal FT from the step S9 similarly to the footrest depression sensor 36 it is determined whether more than a predetermined value FT _0, FT> when FT ₀ Step S2
6; otherwise, to step S21.

At step S21, steps S10, S
15, the absolute value of the target deceleration | Gx ^* |
Is greater than or equal to a predetermined target deceleration value Gx ₀ ^* , and if yes, the process proceeds to step S24; otherwise, the process proceeds to step S22.

In step S22, it is determined whether or not the current preliminary braking fluid pressure target value P _PB is equal to or greater than 0.3 MPa, and if it is greater than or equal to 0.3 MPa, the current preliminary braking fluid pressure target value P _PB is determined. The process _proceeds to step S30 without updating P _PB , and otherwise, proceeds to step S23 to set the preliminary braking fluid pressure target value P _PB to 0.3 MPa, and then proceeds to step S30. This is to maintain the preliminary braking control in the previous process.

On the other hand, if the determination in step S21 is Yes, the process proceeds to step S24, where it is determined whether or not the current preliminary braking fluid pressure target value P _PB is 0.4 MPa or more. If it is .4 MPa or more, the process proceeds to step S30 without updating the current preliminary braking fluid pressure target value P _PB ; otherwise, the process proceeds to step S25.
The program proceeds to step S30 to set the preliminary braking fluid pressure target value P _PB to 0.4 MPa, and then proceeds to step S30. This is to maintain the preliminary braking control in the previous process.

On the other hand, if the determination in step S20 is Yes, the process proceeds to step S26, and the absolute value | Gx ^* | of the target deceleration is set in advance by the same processing as in steps S10, S15, and S21. It is determined whether or not the target deceleration predetermined value Gx ₀ ^{* is} equal to or greater than the threshold value. If the determination is Yes, the process proceeds to step S29.

In step S27, it is determined whether or not the current preliminary brake fluid pressure target value P _PB is 0.5 MPa or more. If it is 0.5 MPa or more, the current preliminary brake fluid pressure target value P _PB is determined. The process _proceeds to step S30 without updating P _PB , otherwise, the process proceeds to step S28 to set the preliminary braking fluid pressure target value P _PB to 0.5 MPa, and then proceeds to step S30. This is to maintain the preliminary braking control in the previous process.

On the other hand, if the determination in step S26 is Yes, the flow shifts to step S29 to set the preliminary braking fluid pressure target value P _PB to 0.6 MPa, and then shifts to step S30.

At step S30, the preliminary braking control counter CNT is incremented, and the routine goes to step S31.

[0069] At step S31, it is determined whether or not the preliminary braking control counter CNT is preliminary braking count-up a predetermined value CNT ₀ or more. The preliminary braking control counter C
If NT is equal to or greater than the preliminary braking count-up predetermined value CNT ₀ , the flow shifts to step S 32, otherwise returns. Here, the preliminary braking count-up predetermined value CNT ₀ takes into account the elapsed time that the driver will depress the brake pedal 23 after the preliminary braking is determined to be necessary in steps S8, S9, and S10. And set. In this embodiment, it is set to one second, but this means that the driver will depress the brake pedal 23 within one second after it is determined that the preparatory braking is required, and if not, the preparatory braking is required. Based on thinking that the judgment was a misjudgment. Of course, the preliminary braking count-up predetermined value CNT ₀ can be set arbitrarily.

In step S32, the preliminary brake fluid pressure target value P _PB is set to 0 MPa, and the preliminary brake control counter CNT is set to an initial value 0, and the routine returns.

Steps S13, S16, S18,
The reason for not updating the current preliminary braking fluid pressure target value P _PB in S22, S24, and S27 is to maintain the preliminary braking control in the previous process.

Next, the operation of the present embodiment will be described.

If the driver is depressing the brake pedal 23 or the accelerator pedal 27 while the vehicle is running, it is not necessary to perform the preliminary braking control, so the determination in step S6 or S7 is YES. Then, the process proceeds to step S12, where the preliminary braking fluid pressure target value P _PB is set to 0 MPa.

On the other hand, when the driver has not depressed any of the brake pedal 23 and the accelerator pedal 27, the operation is as follows.

(1) When the target deceleration for avoiding contact with the obstacle in front is less than a predetermined value Even if the return speed of the accelerator pedal 27 operated by the driver is not higher than a predetermined value and the biological reaction of the driver is higher than a predetermined value. If there is no target and the target deceleration for avoiding contact with the forward obstacle is less than the predetermined value (all of the first to third evaluation indices are not satisfied), the preliminary braking fluid pressure target value P _PB has already been set. 0
It is determined whether or not the value exceeds MPa. If the preliminary brake fluid pressure target value P _PB was 0MPa, the process proceeds to step S12 determination in step S11 becomes a No, but sets a preliminary brake fluid pressure target value P _{P B} in 0MPa, preliminary braking If the fluid pressure target value P _PB has already exceeded 0 MPa, preliminary braking control is executed based on the value (steps S11, S30 to S32). As a result, when the preliminary braking control has been performed in the previous process, the preliminary braking control is maintained.

(2) When the target deceleration for avoiding contact with the obstacle ahead is equal to or higher than a predetermined value. If there is no target and the target deceleration for avoiding contact with the forward obstacle is equal to or more than a predetermined value (only the third evaluation index is satisfied), it is determined that the preliminary braking control needs to be performed, and Preliminary braking control processing for controlling the solenoid valve 5 of the electronic negative pressure booster 24 based on the value of the braking fluid pressure target value P _PB
Preliminary braking count-up predetermined value CNT ₀ which is a predetermined time
, Specifically for one second. Here, the preliminary braking fluid pressure target value P _PB is set to 0.1 MPa,
At this time, if the preliminary braking fluid pressure target value P _PB has already exceeded 0.1 MPa, the preliminary braking control is executed based on the value (steps S10, S13, S14). As a result, even when the preliminary braking fluid pressure target value P _PB changes in the preliminary braking control, the value of the preliminary braking fluid pressure target value P _PB is maintained at the value in the previous processing.

(3) The footrest depression force exceeds a predetermined value
When the return speed of the accelerator pedal 27 operated by the driver is
In addition, the footrest treading force exceeds the specified value
If it is determined that the biological reaction of the driver is more than a predetermined,
Judging that it is necessary to execute the preliminary braking control,
Fluid pressure target value P _PBBased on the value of the electronic negative pressure booth
A preliminary braking control process for controlling the electromagnetic valve 5 of the
Preliminary braking count-up predetermined value CNT which is time₀of
For a period of time, specifically for one second. Where the spare
Braking fluid pressure target value P_PBSetting further touches obstacles ahead
To determine whether the target deceleration for
Do it with taste.

In the above description, if the target deceleration for not contacting the front obstacle is not more than the predetermined value (only the second evaluation index is satisfied), the preliminary braking fluid pressure target value P _PB is set to the third evaluation index. 0.2 which is larger than the case where only
Set to MPa. This is because the second evaluation index is related to the biological response of the driver and the driver is more likely to shift to the braking operation than the third evaluation index. Is weighted more than the third evaluation index. If the driver's target pre-brake fluid pressure value P _PB has already exceeded 0.2 MPa, the pre-brake control is executed based on the pre-brake fluid pressure target value in the same manner as in (1) above (steps S9 and S15). To S17).

On the other hand, if the target deceleration for avoiding contact with the front obstacle is equal to or greater than the predetermined value (the second and third evaluation indexes are satisfied), the preliminary braking fluid pressure target value P _PB is set to the second value. The value when only the evaluation index is satisfied and the value when only the third evaluation index is satisfied are set to 0.3 MPa. This is based on the idea of considering both the fact that a plurality of evaluation indices are satisfied and the weighting of the evaluation indices themselves. Note that the preliminary braking fluid pressure target value P _PB is already 0.3
If the value exceeds MPa, the preliminary braking control is executed based on the value in the same manner as in (1) above (step S1).
9, S15, S18, S19).

(4) When the return operation of the accelerator pedal is faster than a predetermined speed It is determined that the preparatory braking control needs to be executed, and based on the value of the preparatory braking fluid pressure target value P _PB , Preliminary braking control processing for controlling the solenoid valve 5 of the negative pressure booster 24 is performed for a predetermined time, that is, a predetermined value CNT ₀ of the preliminary braking count-up, specifically, for one second. Here, the setting of the preliminary braking fluid pressure target value P _PB is further performed based on whether or not the footrest depressing force exceeds a predetermined value and whether or not the target deceleration for preventing contact with a forward obstacle is equal to or more than a predetermined value.

(4-1) When the Foot Rest Treading Force Does Not Exceed a Predetermined Value In the above, when the target deceleration for not contacting the front obstacle is not more than the predetermined value (only the first evaluation index is satisfied) The preliminary brake fluid pressure target value P _PB is set to 0.3 MPa which is larger than the case where only the second evaluation index is satisfied. This is because the operation of returning the accelerator pedal 27 by the driver is performed prior to the braking operation, and the biological reaction of the driver when the driver finds an obstacle ahead is performed before the operation of returning the accelerator pedal 27 by the driver. This is based on the fact that the first evaluation index is weighted more than the second evaluation index, based on the idea that it will occur. When the preliminary braking fluid pressure target value P _PB of the driver has already exceeded 0.3 MPa, the preliminary braking control is executed based on the value in the same manner as in the above (1) and (2) (step (1)). S8, S2
0 to S23).

On the other hand, when the target deceleration for avoiding contact with the front obstacle is equal to or more than the predetermined value (the first and third evaluation indices are satisfied), the target pre-brake fluid pressure value P _PB is set to the first value. The value obtained when only the evaluation index is satisfied and the value obtained when only the third evaluation index is satisfied are set to 0.4 MPa. This is based on the idea of considering both the fact that a plurality of evaluation indices are satisfied and the weighting of the evaluation indices themselves. Note that the preliminary braking fluid pressure target value P _PB is already 0.4
When the value exceeds MPa, the above items (1) and (2)
Similarly, the preliminary braking control is executed based on the value (steps S8, S20, S21, S24, S25).

(4-2) When the Footrest Depressing Force Exceeds a Predetermined Value In the above, when the target deceleration for not contacting the front obstacle is not more than the predetermined value (the first and second evaluation indexes are satisfied) ) Is set to 0.5 MPa by summing the value of the preliminary braking fluid pressure target value P _PB when only the first evaluation index is satisfied and the value when only the second evaluation index is satisfied. I do. This is based on the idea of considering both the fact that a plurality of evaluation indices are satisfied and the weighting of the evaluation indices themselves. If the driver's preliminary braking fluid pressure target value P _PB has already exceeded 0.5 MPa, the above item (1)
As in (2), the preliminary braking control is executed based on the value (steps S8, S20, S26 to S28).

On the other hand, when the target deceleration for avoiding contact with the front obstacle is equal to or more than the predetermined value (all the first, second and third evaluation indices are satisfied), the preliminary braking fluid pressure target value P _PB
The sum of the value when only the first evaluation index is satisfied, the value when only the second evaluation index is satisfied, and the value when only the third evaluation index is satisfied is 0.6 MPa. Set to. This is based on the idea that both the fact that a plurality of evaluation indices are satisfied and the weighting of the evaluation indices themselves are taken into account (steps S8, S20, S26, S29).

Next, the effect of this embodiment will be described.

In this embodiment, the first evaluation index indicating that the return speed of the accelerator pedal 27 is equal to or higher than a predetermined value, the second evaluation index indicating that the biological response of the driver is equal to or higher than a predetermined value, the vehicle speed Vm, The preliminary braking fluid pressure target value P is determined based on a plurality of evaluation indices such as a third evaluation index in which the state of approach to an obstacle ahead of the vehicle obtained from the relative distance is equal to or greater than a predetermined value.
Set _PB . By weighting each of the three evaluation indices such that the first evaluation index> the second evaluation index> the third evaluation index, it is ensured that the driver may enter the braking operation. As a result, it is possible to increase the certainty of determining whether or not to execute the preliminary braking control, thereby minimizing discomfort to the driver when performing the preliminary braking control.

When a plurality of evaluation indices among the above three evaluation indices are established, by combining these plurality of evaluation indices, the more the number of evaluation indices, the greater the urgency By setting as, it is possible to more reliably estimate the possibility that the driver will enter the braking operation.

Further, when the value of the preliminary brake fluid pressure target value P _PB is smaller than the previous value, the value of the preliminary brake fluid pressure target value P _PB is not updated. By maintaining, the effect of the preliminary braking control can be sufficiently exerted, and the fluctuation of the preliminary braking fluid pressure can be suppressed.

As described above, the electronic negative pressure booster 24 constitutes the preliminary braking means, and similarly, the control device 29 and the entire arithmetic processing of FIGS. 4 and 5 executed here constitute the preliminary braking control means. , The accelerator pedal 27 constitutes the acceleration operation means, the accelerator stroke sensor 28 constitutes the acceleration operation change amount detection means, the footrest treading force sensor 36 constitutes the biological reaction detection means, and the control device 29 includes step S10 in FIG. , S15 and steps S21, S2 in FIG.
6 constitutes an approach state detecting means, and steps S8 to S10 and S15 in FIG. 4 of the control device 29 and steps S20, S21 and S26 in FIG. Steps S12, S14, S1
7, S19 and steps S23, S25, S2 in FIG.
8, S29 constitutes the preliminary braking force correction means.

In this embodiment, a plurality of evaluation fingers
Preliminary braking corresponding to each evaluation index when combining targets
Fluid pressure target value P_PB, But is not limited to this.
Weights, for example, each evaluation index
A constant may be added. Also, for example, each evaluation
You can multiply the value corresponding to the metric,
In this case, the preliminary braking fluid pressure target value P corresponding to each evaluation index_PB
If is simply multiplied when is less than one,
The larger the evaluation index, the more the preliminary braking fluid pressure target value P _PBIs small
Pre-brake fluid pressure target to be multiplied
Value P_PBMultiplied by an appropriate number to obtain a value of 1 or more
Dynamic fluid pressure target value P_PBAfter performing mutual multiplication,
It is necessary to perform processing such as division by a large number. Also examples
For example, set weighting constants corresponding to each evaluation index,
The weighting constant is set to the preliminary braking fluid pressure target value P._PBMultiply by
You may do it.

As a biological reaction detecting means, as disclosed in Japanese Patent Application Laid-Open No. H11-286264, a sensor for detecting grip force, heart rate, changes in muscle contraction, sweating, etc., is provided on the steering wheel. Or JP
As disclosed in Japanese Patent Publication No. 0-24818, a sensor for measuring a change in axial force of a steering rotation shaft may be provided. In this case, it is configured to determine whether or not the detection value of the sensor has reached a predetermined value or more in step S9 in FIG. 4 and step S20 in FIG. Similarly, a load sensor may be provided on the sheet to serve as a biological reaction detection unit. In this case, the unit per unit time (for example, one second) is used in step S9 in FIG. 4 and step S20 in FIG.
It is configured to determine whether or not the peak value of the load change at the time is equal to or more than a predetermined value.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a negative pressure booster according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating a temporal relationship between a driver's accelerator returning operation and a driver's biological reaction with respect to a driver's braking operation.

FIG. 4 is a flowchart illustrating a calculation process of the control device according to the embodiment of the present invention.

FIG. 5 is a flowchart illustrating a calculation process of the control device according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Variable pressure chamber 2 Negative pressure chamber 3 Vacuum valve 4 Atmospheric valve 5 Solenoid valve 6 Operating rod 8 Push rod 23 Brake pedal 24 Electronic negative pressure booster 25 Master cylinder 26 Brake switch 27 Accelerator pedal 28 Accel stroke sensor 29 Control device 30 Vehicle speed sensor 31 Inter-vehicle distance sensor 34 Changeover switch 35 Footrest 36 Footrest treading force sensor

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Akihiko Kobayashi Nissan Motor Co., Ltd. F-term (reference) 3D046 BB18 CC02 HH02 HH16 HH18 HH20 HH22 LL02 LL05 LL23 LL23

Claims (12)

[Claims] 1. A preliminary braking means for generating a preliminary braking force independently of a driver's braking operation; a preliminary braking control means for controlling a preliminary braking force generated by the preliminary braking means; An acceleration operation unit that is operated according to an intention; an acceleration operation change amount detection unit that detects an acceleration operation change amount of the acceleration operation unit; An approaching state detecting means for detecting an approaching state to an obstacle in front of the vehicle,
An urgency evaluation means for evaluating the urgency from at least one of them; A braking control device comprising: a power correction unit. 2. The urgency evaluation unit includes: a first evaluation unit that sets a first evaluation index from the acceleration operation change amount; and a second evaluation unit that sets a second evaluation index from the biological reaction. And a third evaluation unit that sets a third evaluation index from the approach state, and any one of the first evaluation index, the second evaluation index, and the third evaluation index When only one evaluation index is set, the evaluation index is set as the evaluation urgency of the urgency evaluation means, and the first evaluation index, the second evaluation index, and the third evaluation are set. 2. The method according to claim 1, wherein when a plurality of evaluation indices are set among the indices, a composite evaluation index obtained by combining the plurality of evaluation indices is used as the evaluation urgency of the urgency evaluation means. 3. Braking control device. 3. The braking control device according to claim 2, wherein the urgency evaluation means performs an adding process on the plurality of evaluation indices to obtain the composite evaluation indices. 4. The braking control device according to claim 2, wherein the urgency evaluation means performs a multiplication process on the plurality of evaluation indices to obtain the composite evaluation indices. 5. The method according to claim 2, wherein the urgency evaluation means sets the first evaluation index as an urgency higher than the second evaluation index and the third evaluation index. The braking control device according to any one of the preceding claims. 6. The braking control device according to claim 2, wherein the urgency evaluation means sets the second evaluation index as an urgency higher than the third evaluation index. 7. The urgency evaluation means sets a composite evaluation index obtained by combining the second evaluation index and the third evaluation index to be equal to the first evaluation index. The braking control device according to claim 2, wherein 8. The preliminary braking control means determines the start of the preliminary braking when it is determined based on the approach state that the own vehicle is approaching an obstacle in front of the vehicle. 8. The braking control device according to claim 1, wherein: 9. The braking control device according to claim 1, wherein the preliminary braking control means determines the start of the preliminary braking when the biological reaction is detected. 10. The preliminary braking control means determines that the preliminary braking is to be started when the acceleration operation change amount is negative and the absolute value of the acceleration operation change amount is equal to or greater than a predetermined value. The braking control device according to claim 1, wherein 11. A vehicle further comprising: relative distance detecting means for detecting a relative distance to an obstacle ahead of the vehicle; and own vehicle speed detecting means for detecting a speed of the own vehicle. The braking control device according to claim 1, wherein the approach state is detected by using the speed of the host vehicle. 12. The braking system according to claim 1, wherein the preliminary braking force correction unit does not update the preliminary braking force when the preliminary braking force has a smaller value than the previous braking force. Control device.