JPH06144072A - Vehicle controller - Google Patents

Abstract

PURPOSE:To secure safety in a vehicle despite lack of a driver's ability by comprising an automatic control meansbraking its own car in the case where an actual distance to be detected by a forward distance sensor is shorter than the set safety distance when steerage is detected. CONSTITUTION:A current actual car-to-car distance LR is detected by a car range sensor 72 and then a current car speed V is detected by a car speed sensor 76. In addition, the last value is subtracted from this time value of the actual car-to-car distance LR whereby a time differentiated value of this actual car-to-car distance is calculated, and it is set to a relative speed difference DELTAV. Successively, a safety car-to-car distance LSF is calculated as well. Relations among the car speed V, the safety car-to-car distance LSF and the relative speed difference DELTAV are prestored in a read-only memory, and with these relations used, the safety car-to-car distance LSF to be confromed to both the current values of the car speed V and the relative speed difference DELTAV is determined.

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 the driver's lack of driving ability on the vehicle side. The present invention relates to a technique for improving vehicle safety when avoiding a rear-end collision with an obstacle.

[0002]

2. Description of the Related Art A vehicle control device has been proposed which compensates for a driver's lack of driving ability on the vehicle side to improve vehicle safety. As one example thereof, 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 becomes equal to or lower than the reference yaw rate without correction steering by the driver. It is a vehicle yaw motion control device for controlling a vehicle.

[0003]

By the way, it may be necessary to avoid a rear-end collision with a front obstacle by steering by a driver. In this case, a rear-end collision can be avoided without vehicle braking. In other cases, it may not be possible to avoid a rear-end collision without vehicle braking. And
In the latter case, due to the driver's lack of driving skill and lack of attention at the front, he or she tries to avoid a rear-end collision by steering without a braking operation, and as a result, a rear-end collision with a front obstacle cannot be sufficiently avoided. Things can happen. On the other hand, there is a certain relationship between the vehicle speed and the safety distance, which is the minimum value of the distance to the front obstacle, which can avoid a rear-end collision with the front obstacle by steering even without braking operation. .

The present invention utilizes the relationship between the safety distance and the vehicle speed to predict whether or not a rear-end collision with a front obstacle can be avoided by steering without a braking operation. If it is predicted that the vehicle will be automatically braked to ensure the safety of the vehicle regardless of the driver's lack of driving ability.

[0005]

In order to solve this problem, the present invention provides (a) a vehicle control device for improving the safety of a vehicle by compensating the driver's lack of driving ability on the vehicle side. A front distance sensor 1 for detecting a distance between the vehicle and an obstacle existing in front of the vehicle, (b) steering detecting means 2 for detecting steering of the driver with respect to the own vehicle, and (c) traveling speed of the own vehicle. Based on the detected vehicle speed sensor 3 and (d) the vehicle speed detected by the vehicle speed sensor 3, the safe distance, which is the minimum distance that can avoid a rear-end collision with an obstacle ahead of the vehicle without braking if steering is started. 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, the automatic braking means 4 for braking the host vehicle Is characterized by including It

Incidentally, the "automatic braking means 4" here
Is not only the mode in which the brakes on the wheels are applied, but also the mode in which the effect of engine braking is increased by increasing the speed reduction ratio of the transmission of the vehicle while the vehicle is not being accelerated. it can.

Further, the "automatic braking means 4" here
According to the relationship existing between the vehicle speed of the host vehicle and the safety distance, the present embodiment can determine the present value of the safety distance corresponding to the present value of the vehicle speed of the host vehicle. It should be noted that the "front obstacle" in this aspect can be either a stationary object on the road surface or a vehicle that is a moving object. However, when a vehicle is selected, the "safety distance" is Assuming that the vehicle is suddenly braked, it means the inter-vehicle distance that can avoid a rear-end collision with a vehicle ahead by steering even without a braking operation.

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

[0009]

In the vehicle control device according to the present invention, the front distance sensor 1 detects the distance between the own vehicle and the front obstacle, and the steering detecting means 2 detects the steering of the driver with respect to the own vehicle and the vehicle speed. The sensor 3 detects the traveling speed of the host vehicle. Further, the automatic braking means 4 successively determines the safety distance, which is the minimum value of the distance that can avoid the rear-end collision with the front obstacle without braking if the steering is started, based on the vehicle speed detected by the vehicle speed sensor 3. 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 determined safety distance, the host vehicle is braked. That is, the vehicle is automatically braked when there is a possibility that a rear-end collision with a front obstacle cannot be avoided by steering without vehicle braking.

[0010]

As described above, according to the present invention, the vehicle is automatically braked when it is not possible to avoid a rear-end collision with a front obstacle by steering without vehicle braking. The effect that the lack of the driving ability of the driver is compensated for on the vehicle side and the safety of the vehicle is improved is obtained.

[0011]

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

This vehicle control device is provided in a four-wheel vehicle equipped with an electrically controlled braking system. This electrically controlled braking system, as shown in FIG.
The master cylinder 10 and the electrically controlled hydraulic pressure source 12 are configured to be connected via a two-position valve 14 to the wheel cylinders 20 of the brakes of each of the four wheels FR, FL, RR, RL. The two-position valve 14 allows either the master cylinder 10 or the electrically controlled hydraulic pressure source 12 to be selected 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 mechanical pressure is generated in the pressurizing chambers at a height corresponding to the pedaling force F of the brake pedal 24. One of the pressurizing chambers has front left and right wheels FL, F.
It is connected to the R wheel cylinder 20 and the other pressurizing chamber is connected to the wheel cylinders 20 of the left and right rear wheels RL and RR.

On the other hand, the electrically controlled hydraulic pressure source 12 includes an accumulator 30, a pump 34 for pumping hydraulic fluid from a reservoir 32 and storing it in the accumulator 30, and a linear hydraulic control valve for controlling the hydraulic pressure to a height proportional to the exciting current. 40 and the like, the high hydraulic pressure accumulated in the accumulator 30 is reduced to an appropriate height by the linear hydraulic 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 valve 40 is provided individually for each wheel cylinder 20 and controls the brake pressure of each wheel cylinder 20 independently of each other.

The two-position valve 14 is also used for each wheel cylinder 2
0 is provided individually. The two-position valve 14 is in a position where the master cylinder 10 communicates with the wheel cylinder 20 and the linear hydraulic pressure control valve 40 is shut off from the wheel cylinder 20 in the non-energized state. 40 for wheel cylinder 20
Is a directional control valve that connects the master cylinder 10 to the position where the master cylinder 10 is disconnected from the wheel cylinder 20.

As shown in FIG. 3, the linear hydraulic control valve 40 and the two-position valve 14 are connected to the drive circuit 50,
ECU (Electronic Controlled Unit) 6 via 52
It is connected to the output side of 0. On the other hand, 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, etc. are connected to the input side of the ECU 60.

Here, the pedal effort sensor 70 detects the pedal effort 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, or 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 which is a traveling speed of the vehicle. The pressure sensor 78 is provided individually for each wheel cylinder 20,
The actual brake pressure P thereof is detected.

The ECU 60 is a CPU, ROM and RAM
The ROM is provided with various routines including a pedaling force-brake pressure control routine represented by a flowchart in FIG. 4 and an automatic brake control routine represented by a flowchart in FIG. It is stored in advance. The CPU executes these routines based on various input signals to sequentially determine whether or not the electrically controlled hydraulic pressure source 12 is normal, and when it is determined to be normal, the two-position valve is used. 14
Is energized, and pedal force-brake pressure control and automatic brake control are executed.

The pedaling force-brake pressure control routine shown in FIG.
Briefly explaining, braking is performed via the linear hydraulic pressure control valve 40 so that a braking force suitable for realizing a vehicle deceleration of a magnitude commensurate with the pedaling force F of the brake pedal 24 is generated on each wheel. It controls the pressure.

This routine is executed at regular time intervals.
In each execution, first, step S1 (hereinafter, simply S1
Say. In other steps), the pedal effort F is taken in from the pedal effort sensor 70, and then,
At S2, the target brake pressure P corresponding to the pedaling force F
^* Is determined for each wheel. ROM in advance
The target brake pressure P ^* is determined based on this relationship. Then, in S3, the linear hydraulic pressure control valve 40 is controlled so that the target brake pressure P ^* is realized. Linear hydraulic control valve 4
0 is controlled while the actual brake pressure P is fed back via the pressure sensor 78. With the above, one execution is completed.

On the other hand, the automatic brake control routine of FIG. 5 is roughly described. The relative speed difference ΔV (larger than the vehicle speed V of the own vehicle and a value obtained by subtracting the vehicle speed V _F of the preceding vehicle from the vehicle speed V is large. (Which means that the vehicle speed V of the host vehicle is faster than the vehicle speed V _{F of the} front vehicle) and a safe inter-vehicle distance that can avoid a rear-end collision with the front vehicle without braking if steering is started. Based on the relationship obtained in
The safety inter-vehicle distance LSF is sequentially determined, and when the actual inter-vehicle distance LR is shorter than the determined safety inter-vehicle distance LSF when steering by the driver is started, the brake of the own vehicle is automatically applied. It is a thing. Specifically, as shown in the graph of FIG.
The greater the vehicle speed V of the host vehicle, the longer the safe inter-vehicle distance LSF, and the greater the relative speed difference ΔV (that is,
(The faster the own vehicle is than the preceding vehicle), the safe inter-vehicle distance LSF
Will be long.

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 in the non-braking state where the pedal effort F is 0, that is, the pedal effort-brake pressure control by the pedal effort-brake pressure control routine of FIG. 4 is not executed. It is determined whether or not 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,
Assuming that the vehicle is not being braked, the determination is YES, and the process proceeds to steps S102 and thereafter. That is, this automatic braking control is executed only when the vehicle is not being 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 greater than a threshold value. If this time is not the case, the determination is NO, and one execution of this routine ends, but if this time is the case, the determination is YES, and the process proceeds to steps S103 and thereafter.

In S103, the inter-vehicle distance sensor 72 detects the current actual inter-vehicle distance LR, and thereafter,
At 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, which is set as the relative speed difference ΔV, and subsequently in S106, the safe inter-vehicle distance The 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 advance in the ROM, and this relationship is used to calculate the current value of the vehicle speed V and the current value of the relative speed difference ΔV. The safe inter-vehicle distance LSF corresponding to both is determined.

Thereafter, in S107, the actual inter-vehicle distance L
It is determined whether SF is shorter than the safe inter-vehicle distance LSF. Assuming that it is short, the determination is yes and S108
At, the actual brake pressure P is increased via the linear hydraulic pressure control valve 40, whereby the vehicle is automatically braked. On the other hand, assuming that the actual inter-vehicle distance LSF is not shorter than the safe inter-vehicle distance LSF this time, S107.
Is NO, and S108 is skipped. Thus, one execution of this routine is completed.

When the electrically controlled hydraulic pressure source 12 is activated, the two-position valve 14 prevents the hydraulic fluid from being discharged from the master cylinder 20, that is, the displacement of the brake pedal 24. Will be quite stiff. Therefore, even when the electrically controlled hydraulic pressure source 12 is enabled, in order to obtain a brake operation feeling almost similar to that when the master cylinder 10 is enabled,
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. While the electric control hydraulic pressure source 12 is enabled, the two-position valve 90 is energized and kept in the open state, whereby the hydraulic fluid discharged from the master cylinder 10 is accumulated under pressure, whereby The displacement of the brake pedal 24 is realized in a pseudo manner.

The case where it is determined that the electrically controlled hydraulic pressure source 12 is normal has been described above. However, when it is determined that the electric control hydraulic pressure source 12 is not normal, the ECU 60 causes the two-position valves 14 and 9 to operate.
0 is de-energized to enable the master cylinder 10,
Depending on the operation of the brake pedal 24, the wheel cylinder 2
The brake pressure of 0 is mechanically changed.

As is apparent from the above description, in the present embodiment, the vehicle is automatically braked when there is a possibility that the rear-end collision with the vehicle ahead cannot be avoided by the steering without the braking operation. Therefore, the effect of avoiding a rear-end collision with a vehicle ahead is obtained. Even if the driving ability of the driver is insufficient, it is compensated by the vehicle side, and as a result, it is possible to obtain the effect of avoiding a rear-end collision with the vehicle in front.

Further, in the present embodiment, the vehicle speed V _F of the preceding vehicle is predicted by using the time differential value of the actual vehicle distance LR, and the safety vehicle distance LSF is determined in consideration of this. 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 aspect of the "front distance sensor 1" of the present invention, and the steering angle sensor 74
5 and a portion of the ECU 60 that executes S102 of FIG. 5 cooperate with each other to configure one aspect of the “steering detection means 2” of the present invention.
The part that executes 8 is the "automatic braking means 4" in the present invention.
It constitutes one aspect.

Although one embodiment of the present invention has been described in detail with reference to the drawings, various modifications and improvements can 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 such a mode.

[Brief description of drawings]

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

FIG. 2 is a system diagram showing an electrically controlled brake system provided with a vehicle control device according to an 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 the ECU in FIG.

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

FIG. 6 is a graph showing the relationship between the vehicle speed V of the host vehicle, the safe inter-vehicle distance LSF, and the 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

Claims (1)

[Claims] 1. A front distance sensor for detecting a distance between an own vehicle and an obstacle existing in front of the own vehicle, a steering detecting means for detecting steering of a driver with respect to the own vehicle, and a traveling speed of the own vehicle. Based on the detected vehicle speed sensor and the vehicle speed detected by the vehicle speed sensor, the safety distance, which is the minimum value of the distance that can avoid a rear-end collision with the front obstacle without braking if steering is started, is sequentially determined. At the same time, when the actual distance detected by the front distance sensor when the steering is detected by the steering detecting means is shorter than the determined safety distance, an automatic braking means for braking the host vehicle is included. A characteristic vehicle control device.