JP3134559B2 - Vehicle control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle control device for improving the safety of a vehicle by compensating for the driver's lack of driving ability on the vehicle side. The present invention relates to a technique for improving the safety of a vehicle when avoiding a rear-end collision with an obstacle in front.

[0002]

2. Description of the Related Art A vehicle control device has been proposed which improves the safety of a vehicle by compensating for the lack of driving ability of the driver on the vehicle side. For example, as described in Japanese Patent Application Laid-Open No. 1-92543, when the actual yaw rate of the vehicle body exceeds the reference yaw rate, the actual yaw rate is set to be equal to or less than the reference yaw rate without the driver performing corrective steering. 1 is a vehicle yaw motion control device that controls a vehicle.

[0003]

In some cases, it is necessary to avoid a rear-end collision with an obstacle ahead by steering by a driver. In this case, a rear-end collision can be avoided without vehicle braking. In some cases, rear-end collisions cannot be avoided without vehicle braking. And
In the latter case, an attempt is made to avoid a rear-end collision by steering without a braking operation due to a lack of driving skill or a lack of forward attention of the driver, and as a result, it is not possible to sufficiently avoid a rear-end collision with an obstacle. Things can happen. On the other hand, there is a certain relationship between the safety distance, which is the minimum value of the distance to the front obstacle, and the vehicle speed of the host vehicle, which can avoid a rear-end collision with the front obstacle by steering even without braking operation. .

The present invention makes use of the relationship between the safety distance and the vehicle speed to predict whether or not it is possible to avoid a rear-end collision with an obstacle ahead by steering even without a braking operation, and cannot do so. It has been made to secure the safety of the vehicle by automatically braking the vehicle when it is predicted that the driving ability of the driver is insufficient.

[0005]

In order to solve this problem, the present invention provides a vehicle control device for improving the safety of a vehicle by compensating for the lack of driving ability of the driver on the vehicle side. A forward distance sensor 1 for detecting the distance between the vehicle and an obstacle existing in front of the vehicle, (b) steering detection means 2 for detecting the driver's steering of the own vehicle, and (c) a running speed of the own vehicle. (D) a safety distance which is a minimum value of a distance that can avoid a rear-end collision with an obstacle without braking if steering is started based on a vehicle speed sensor 3 to be detected and (d) a vehicle speed detected by the vehicle speed sensor 3 And when the actual distance detected by the front distance sensor 1 when the steering is detected by the steering detecting means 2 is shorter than the determined safety distance, an automatic braking means 4 for braking the own vehicle is provided. It is characterized by including You.

Incidentally, the "automatic braking means 4" here is used.
In addition to the mode in which the brakes of the wheels are actuated, for example, the mode in which the effect of engine braking is increased by increasing the reduction ratio of the transmission of the vehicle in a state where the vehicle is not being accelerated may also be used. it can.

The "automatic braking means 4" here is
May be a mode in which the present value of the safety distance is determined in accordance with the present value of the vehicle speed of the own vehicle according to the relationship existing between the vehicle speed of the own vehicle and the safe distance. Note that in this embodiment, the “front obstacle” may be a stationary object on the road surface or a vehicle that is a moving object. Means the inter-vehicle distance at which rear-end collision with the preceding vehicle can be avoided by steering even without braking operation when it is assumed that the vehicle is suddenly braked.

On the other hand, the time differential value of the distance between the host vehicle and the obstacle ahead is equal to the difference between the vehicle speed of the host vehicle and the speed of the front vehicle which is an example of the obstacle ahead. , The speed of the preceding vehicle can be predicted. There is also a certain relationship between the vehicle speed of the host vehicle, the safety distance, and the vehicle speed of the vehicle ahead. Therefore, the "automatic braking means 4" according to the present invention uses the present value of the vehicle speed of the own vehicle and the current value of the vehicle speed of the preceding vehicle in accordance with the relationship existing between the vehicle speed of the own vehicle, the safety distance, and the vehicle speed of the preceding vehicle. It is also possible to adopt a mode in which the current value of the safe distance is determined corresponding to both of the above. The “safety distance” in this aspect, unlike the previous aspect, means a distance that can avoid a rear-end collision with the preceding vehicle by steering even without a braking operation, corresponding to the actual running state of the preceding vehicle. Becomes

[0009]

In the vehicle control device according to the present invention, the distance between the host vehicle and the front obstacle is detected by the front distance sensor 1, the steering detection means 2 detects the driver's steering of the host vehicle, and the vehicle speed The traveling speed of the host vehicle is detected by the sensor 3. Further, based on the vehicle speed detected by the vehicle speed sensor 3 by the automatic braking means 4, the safety distance, which is the minimum value of the distance that can avoid collision with a forward obstacle without braking if braking is started, is sequentially determined. If the actual distance detected by the front distance sensor 1 when the steering is detected by the steering detecting means 2 is shorter than the safety distance determined above, the own vehicle is braked. That is, when there is a possibility that the steering cannot avoid a collision with a forward obstacle without the vehicle braking, the vehicle is automatically braked.

[0010]

As described above, according to the present invention, the vehicle is automatically braked when there is a possibility that it is not possible to avoid a rear-end collision with an obstacle ahead by steering without vehicle braking. In addition, there is an effect that the shortage of the driving ability of the driver is compensated on the vehicle side and the safety of the vehicle is improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a vehicle control device according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that this vehicle control device normally operates regardless of whether the front obstacle is a stationary object or a vehicle. However, since the vehicle is generally a vehicle, hereinafter, the front obstacle is referred to as a “front vehicle”. ”Will be described.

This vehicle control device is provided in a four-wheel vehicle provided with an electrically controlled brake system. This electrically controlled braking system, as shown in FIG.
The master cylinder 10 and the electric control hydraulic pressure source 12 are connected via a two-position valve 14 to the wheel cylinders 20 of the brakes of the four wheels FR, FL, RR, RL. The two-position valve 14 makes it possible to select either the master cylinder 10 or the electric control hydraulic pressure source 12 as the hydraulic pressure source for the wheel cylinder 20.

The master cylinder 10 is of a tandem type in which two pressurizing chambers are arranged in series with each other, and mechanically generates a hydraulic pressure in the pressurizing chambers at a height corresponding to the depression force F of the brake pedal 24. One of the pressure chambers is a front left and right wheel FL, F
The other pressure chamber is connected to the wheel cylinders 20 of the left and right rear wheels RL and RR.

On the other hand, the electric control hydraulic pressure source 12 includes an accumulator 30, a pump 34 for pumping the hydraulic fluid from the reservoir 32 and storing it in the accumulator 30, and a linear hydraulic pressure control valve for controlling the hydraulic pressure to a height proportional to the exciting current. The high hydraulic pressure accumulated in the accumulator 30 is reduced to an appropriate level by the linear hydraulic pressure control valve 40 and output. The linear hydraulic pressure control valve 40 changes the height of the hydraulic pressure linearly with respect to the magnetic force by balancing the magnetic force and the hydraulic pressure acting on the spool in opposite directions by the spool itself. The linear hydraulic pressure control valves 40 are provided individually for each wheel cylinder 20 and control the brake pressure of each wheel cylinder 20 independently of each other.

The two-position valve 14 is also provided for each wheel cylinder 2
0 is provided individually. In the non-energized state, the two-position valve 14 is in a position where the master cylinder 10 is communicated with the wheel cylinder 20 and the linear hydraulic pressure control valve 40 is shut off from the wheel cylinder 20. 40 is the wheel cylinder 20
And a direction switching valve that switches to a position where the master cylinder 10 is disconnected from the wheel cylinder 20.

As shown in FIG. 3, the linear hydraulic pressure control valve 40 and the two-position valve 14 have a drive circuit 50,
ECU (Electronic Controlled Unit) 6 via 52
0 is connected to the output side. On the other hand, an input side of the ECU 60 is connected to a pedaling force sensor 70, an inter-vehicle distance sensor 72, a steering angle sensor 74, a vehicle speed sensor 76, a pressure sensor 78, and the like.

Here, the pedaling force sensor 70 detects the pedaling force F of the brake pedal 24. The inter-vehicle distance sensor 72 detects the actual inter-vehicle distance LR between the host vehicle and the preceding vehicle by, for example, a radio wave type, an ultrasonic type, and an image matching type. The steering angle sensor 74 detects the steering angle θ of the steering wheel steered by the driver. The vehicle speed sensor 76 detects a vehicle speed V that is the traveling speed of the vehicle. The pressure sensors 78 are provided individually for each wheel cylinder 20,
The actual brake pressure P is detected.

The ECU 60 has a CPU, a ROM and a RAM.
The ROM includes various routines such as a pedaling force-brake pressure control routine shown in a flowchart of FIG. 4 and an automatic brake control routine shown in a flowchart of FIG. It is stored in advance. The CPU executes these routines based on the input various signals, thereby sequentially determining whether the electric control hydraulic pressure source 12 is normal or not. 14
Are turned on, and the pedaling force-brake pressure control and the automatic brake control are executed.

The pedaling force-brake pressure control routine shown in FIG.
In brief, the brake is applied via the linear hydraulic pressure control valve 40 so that a braking force appropriate for realizing the vehicle deceleration corresponding to the depression force F of the brake pedal 24 is generated on each wheel. It controls the pressure.

This routine is executed at regular intervals.
At the time of each execution, first, step S1 (hereinafter simply referred to as S1
That. In other steps, the same applies), the pedaling force F is taken in from the pedaling force sensor 70, and subsequently,
In S2, the target brake pressure P corresponding to the pedaling force F
^* Is determined for each wheel. The relationship between the two is ROM
The current value of the target brake pressure P ^* is determined using the relationship. Thereafter, in S3, the linear hydraulic pressure control valve 40 is controlled such that the target brake pressure P ^* is realized. Linear hydraulic pressure control valve 4
0 is controlled while the actual brake pressure P is fed back via the pressure sensor 78. This completes one execution.

Meanwhile, the automatic braking control routine in FIG. 5, if schematically illustrated, the vehicle speed V of the host vehicle, the relative speed difference [Delta] V (large is a value obtained by subtracting the vehicle speed V _F of the forward vehicle from the vehicle speed V and as the vehicle speed V of the host vehicle means faster than the vehicle speed V _F of the front vehicle), experimental between the safe distance capable of avoiding the collision of the forward vehicle without braking by starting steering Based on the relationship obtained on
The safety inter-vehicle distance LSF is sequentially determined, and when the actual inter-vehicle distance LR is shorter than the determined inter-vehicle distance LSF when the driver starts steering, the brake of the own vehicle is automatically applied. Things. Specifically, as shown in the graph of FIG.
As the vehicle speed V of the host vehicle increases, the safe inter-vehicle distance LSF increases, and as the relative speed difference ΔV increases (ie,
The safer the inter-vehicle distance LSF, the faster the host vehicle is than the preceding vehicle)
Is something that gets longer.

This routine is executed at regular intervals.
At the time of each execution, first, in S101 of FIG. 5, it is determined whether or not the vehicle is at the time of non-braking when the pedaling force F is 0, that is, the pedaling force-brake pressure control by the pedaling force-brake pressure control routine of FIG. 4 is not executed. It is determined whether it is in the state. If it is assumed that the vehicle is being braked this time, the determination is N
It becomes O, and one execution of this routine ends. on the other hand,
If it is assumed that the vehicle is not being braked, the determination is YES, and the process proceeds to S102 and subsequent steps. That is, the automatic brake control is executed only when the vehicle is not braked.

In S102, it is determined whether or not the vehicle is being steered, that is, whether or not the absolute value of the steering angle θ detected by the steering angle sensor 74 is equal to or larger than a threshold value. If it is not the case this time, the determination is NO, and one execution of this routine ends, but if it is the case this time, the determination is YES and the process proceeds to S103 and subsequent steps.

In step S103, the current actual distance LR is detected by the distance sensor 72.
In S104, the current vehicle speed V is detected by the vehicle speed sensor 76.
Is detected. Further, in S105, the time differential value of the actual inter-vehicle distance LR is calculated by subtracting the previous value from the current value of the actual inter-vehicle distance LR, and is calculated as the relative speed difference ΔV. LSF is calculated. The relationship between the vehicle speed V, the safe inter-vehicle distance LSF, and the relative speed difference ΔV (FIG. 6) is stored in the ROM in advance, and using this relationship, the current value of the vehicle speed V and the current value of the relative speed difference ΔV are used. The safe inter-vehicle distance LSF corresponding to both is determined.

Then, in S107, the actual inter-vehicle distance L
It is determined whether the SF is shorter than the safe inter-vehicle distance LSF. Assuming that the length is short, the determination is YES and S108
, The actual brake pressure P is increased via the linear hydraulic pressure control valve 40, whereby the vehicle is automatically braked. In contrast, this time, assuming that the actual inter-vehicle distance LSF is not shorter than the safe inter-vehicle distance LSF, S107
Is NO, and S108 is skipped. This completes one execution of this routine.

When the electric control hydraulic pressure source 12 is enabled, the discharge of the hydraulic fluid from the master cylinder 20, that is, the displacement of the brake pedal 24 is prevented by the two-position valve 14, so that the brake operation feeling is reduced. Becomes quite hard. Therefore, even when the electric control hydraulic pressure source 12 is enabled, the same brake operation feeling as when the master cylinder 10 is enabled is obtained.
As shown in FIG. 2, a stroke simulator 92 is connected to the pressurizing chamber of the master cylinder 10 via a two-position valve 90, which is a normally closed electromagnetic on-off valve. As long as the electric control hydraulic pressure source 12 is enabled, the two-position valve 90 is energized and kept open, so that the hydraulic fluid discharged from the master cylinder 10 is accumulated under pressure. The displacement of the brake pedal 24 is simulated.

The case where the electric control hydraulic pressure source 12 is determined to be normal has been described above. If it is determined that the electronic control hydraulic pressure source 12 is not normal, the ECU 60 controls the two-position valves 14 and 9
0 is de-energized and the master cylinder 10 is enabled,
Wheel cylinder 2 according to the operation of brake pedal 24
It is assumed that the brake pressure of 0 is mechanically changed.

As is apparent from the above description, in this embodiment, when there is a possibility that the rearward collision with the preceding vehicle cannot be avoided by steering without the braking operation, the vehicle is automatically braked. Therefore, it is possible to obtain an effect that it is possible to avoid a collision with a vehicle ahead. Even if the driving ability of the driver is insufficient, it is compensated on the vehicle side, so that it is possible to obtain the effect that it is not necessary to collide with the vehicle ahead.

Furthermore, in this embodiment, the vehicle speed V _F of the front vehicle using the time differential value of the actual headway distance LR is predicted, in consideration also it so safe distance LSF is determined Therefore, the effect of improving the accuracy of the safe inter-vehicle distance LSF is also obtained.

As is clear from the above description, in this embodiment, the inter-vehicle distance sensor 72 constitutes one embodiment of the "forward distance sensor 1" of the present invention, and the steering angle sensor 74
5 and the part of the ECU 60 that executes S102 in FIG. 5 constitute one embodiment of the “steering detecting means 2” of the present invention, and S101, 103 to 10 in FIG.
8 is the "automatic braking means 4" in the present invention.
This constitutes one aspect.

Although the embodiment of the present invention has been described in detail with reference to the drawings, various modifications and improvements may be made based on the knowledge of those skilled in the art without departing from the scope of the claims. It is needless to say that the present invention can be implemented in the above-described embodiment.

[Brief description of the drawings]

FIG. 1 is a block diagram conceptually showing the configuration of the present invention.

FIG. 2 is a system diagram showing an electrically controlled brake system provided with a vehicle control device according to one embodiment of the present invention.

FIG. 3 is a block diagram showing an electric system of the vehicle control device.

FIG. 4 is a flowchart showing a pedaling force-brake pressure control routine executed by a computer of an ECU in FIG. 3;

FIG. 5 is a flowchart showing an automatic brake control routine executed by the computer.

FIG. 6 is a graph showing a relationship between a vehicle speed V of the host vehicle, a safe inter-vehicle distance LSF, and a relative speed difference ΔV in the automatic brake control routine.

[Explanation of symbols]

 60 ECU 72 Inter-vehicle distance sensor 74 Steering angle sensor 76 Vehicle speed sensor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B60R 21/00 627 B60R 21/00 624 G08G 1/16

Claims (1)

(57) [Claims] A front distance sensor for detecting a distance between the host vehicle and an obstacle existing in front of the host vehicle; a steering detecting means for detecting a driver's steering of the host vehicle; Based on a vehicle speed sensor to be detected and a vehicle speed detected by the vehicle speed sensor, a safety distance which is a minimum value of a distance that can avoid a rear-end collision with the front obstacle without braking if steering is started is sequentially determined. And when the actual distance detected by the front distance sensor when the steering is detected by the steering detection means is shorter than the determined safety distance, automatic braking means for braking the host vehicle. Characteristic vehicle control device.