JPH06243397A - Vehicle rear-end collision prevention device - Google Patents

Abstract

PURPOSE:To control warning, etc., matching a driver's feeling. CONSTITUTION:An arithmetic unit 18 calculates the degree of danger for vehicle control and controls an alarm device 20 and an automatic brake device 22. Then the arithmetic unit 18 calculates the degree of danger by signals from a vehicle speed sensor 10, an acceleration sensor 12, a range finding sensor 14, and a Doppler sensor 16 and also calculates the rate of variation in the degree of danger. Then the degree of conviction showing the operation state of acceleration or braking that the driver should perform is calculated from the obtained degree of danger and the rate of variation in the degree of danger. Then the degree of danger for a vehicle is calculated from the degree of conviction and the actual operation state of acceleration or braking. Consequently, the control matching the driver's feeling such as early alarming when the accelerator pedal is stepped is performed although the normal degree of danger is same.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle rear-end collision prevention device for performing warning and automatic brake control suitable for the driver's feeling.

[0002]

2. Description of the Related Art Conventionally, various devices have been proposed in order to improve the safety of automobiles, among which a rear-end collision prevention device is known. This rear-end collision preventive device is intended to reduce the number of rear-end collision accidents and improve safety by detecting the danger of rear-end collision and issuing an alarm or activating an automatic brake.

In this rear-end collision prevention device, it is necessary to determine whether or not a rear-end collision accident is likely to occur. Therefore, a radar is mounted on the automobile to detect the inter-vehicle distance to the preceding vehicle, and control the generation of an alarm or the like based on the inter-vehicle distance and the traveling speed of the own vehicle. That is, the appropriate inter-vehicle distance should increase as the traveling speed increases, and in consideration of this point, an alarm is issued when the measured inter-vehicle distance becomes equal to or less than the appropriate inter-vehicle distance.

Further, in Japanese Patent Laid-Open No. 60-91500, in addition to the inter-vehicle distance to the preceding vehicle and the own vehicle speed, the relative speed and the own vehicle acceleration are also detected, and these are comprehensively evaluated to cause a rear-end collision accident. Is calculated, and an alarm, deceleration control by automatic braking, etc. are performed stepwise according to this risk. By such control, more precise rear-end collision prevention can be performed according to the running condition of the vehicle.

[0005]

However, the warning and brake control in the conventional rear-end collision prevention device often do not match the driver's feeling. That is, if an alarm or the like is issued when the driver has relatively little experience, an alarm is issued when the driver does not feel that the driver is in danger, and it is felt that there are many useless alarms. On the other hand, if the warning is limited to a very dangerous case, the warning cannot be issued even if the driver feels dangerous. Then, if the control different from the driver's feeling is performed in this way, there is doubt about the effect of the rear-end collision prevention device, and it is avoided to use this, and eventually the rear-end collision prevention device is not effectively used. There was a problem.

The present invention has been made to solve the above-mentioned problems, and provides a vehicle rear-end collision prevention device capable of performing an appropriate alarm / automatic brake control that matches the driver's feeling. With the goal.

That is, the present inventor has studied a conventional rear-end collision prevention device, and in the conventional device, since the driver's accelerator and brake operation states are not taken into consideration in the risk calculation, the control is a driver's feeling. I found that does not match. For example, when the driver is already operating the brakes, he notices that the distance between the vehicles is small. Therefore, in such a case, an alarm or the like is unnecessary. If the driver is approaching a dangerous distance, the driver first releases the accelerator. Even in such a case, the driver is in a state where he can immediately step on the brake, and the appropriate vehicle distance should be smaller than when he is stepping on the accelerator. The own vehicle acceleration corresponds to the driver's operation situation to some extent, but the influence of the operation on the acceleration appears to some extent, and in control for preventing a rear-end collision, this little delay greatly affects the feeling. Of.

Therefore, the present invention has been completed in consideration of taking into consideration the operating states of the accelerator and the brake in the driver in the calculation of the degree of danger.

[0009]

According to the present invention, in a vehicle rear-end collision prevention device, a traveling condition detecting means for detecting a vehicle speed and an inter-vehicle distance to a front object, and operating conditions of a brake and an accelerator of the vehicle are operated. Situation detecting means, risk calculating means for calculating the risk from the detected vehicle speed and inter-vehicle distance, risk changing rate calculating means for calculating the change rate of the risk from the changing state of the risk, and the calculated risk Degree and risk rate of change, a certainty factor calculating means for calculating a certainty factor representing the degree of accelerator and brake operating conditions that the driver should operate in the situation, a current accelerator and brake operating condition, and the certainty factor. Alarm based on the degree
Vehicle control risk calculating means for calculating a vehicle control risk for determining a vehicle operation control called automatic brake control, and vehicle control means for controlling an alarm / automatic brake according to the value of the vehicle control risk. And having.

[0010]

In the present invention, the risk level is detected from the vehicle speed and the inter-vehicle distance, and the risk level change rate is detected from the risk level change rate. Next, the degree of certainty regarding the accelerator / brake operation status of the driver is calculated from the degree of danger and the rate of change in degree of danger. Then, the risk level for vehicle control for controlling the alarm automatic brake is calculated based on both the actual accelerator and brake operation status and the certainty factor,
The alarm and the automatic braking are controlled based on the vehicle danger level.

In this way, in addition to the certainty factor regarding the accelerator / brake operation situation which is considered to be operated by the driver, in addition to the actual operation situation of the accelerator and the brake operation, the control according to the situation of the driver is performed. It is possible to perform the control such as an alarm suitable for the driver's feeling.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of the embodiment, which has a vehicle speed sensor 10, an acceleration sensor 12, a distance measuring sensor 14, and a Doppler sensor 16 as detecting means. The vehicle speed sensor 10 detects the speed of the own vehicle, for example, based on the rotation speed of the wheels. The acceleration sensor 12 detects the acceleration by, for example, generating a voltage according to the acceleration in the piezoelectric body. The distance measuring sensor 14 emits a laser, a millimeter wave, or the like toward the front, and detects the distance (inter-vehicle distance) to the vehicle ahead by the time until the reflected wave arrives. The Doppler sensor 16 emits microwaves and millimeter waves forward, and detects the relative speed with respect to the vehicle ahead from the Doppler shift in the reflected wave. The relative speed may be calculated by the time derivative of the inter-vehicle distance, and the own vehicle acceleration may be calculated by the time derivative of the own vehicle speed.

Detection signals from the vehicle speed sensor 10, the acceleration sensor, the distance measuring sensor 14, and the Doppler sensor 16 are supplied to the arithmetic unit 18. The arithmetic unit 18 is usually composed of a microcomputer and performs a predetermined arithmetic processing based on various detection signals supplied. In the arithmetic unit 18,
An alarm device 20 and an automatic braking device 22 are connected, and perform an alarm and a braking operation, respectively, in response to a command from the computing device 18. As the alarm device 20, for example, an alarm buzzer, and as the automatic braking device, for example, a device for forcibly driving a hydraulic pump of the brake to stop the vehicle is adopted. The accelerator switch 24 detects whether or not the accelerator is depressed. The brake switch 26 detects whether or not the brake is depressed.

Next, the operation of the apparatus of this embodiment will be described. First, FIG. 2 shows the relationship between the vehicle speed v and the appropriate inter-vehicle distance x when the driver normally drives. In this way, the appropriate inter-vehicle distance x also increases as the vehicle speed v increases. This relationship is expressed as x = f (v).

Here, the driving situation of the driver is the vehicle speed v0.
, If the inter-vehicle distance is x0, the appropriate inter-vehicle distance x00 during normal driving is x00 = f (v0), and the difference between the appropriate inter-vehicle distance x00 and the actual inter-vehicle distance x0 is the driver's sense of danger, that is, The degree of danger at that time is w0.

W0 = w (v0, x0) = x00-x0 Next, when the rate of change dw / dt of the risk w is calculated, w (v, x) = f (v) -x The rate of change in degree dw / dt is dw / dt = (δw / δt) · dx / dt + (δw / δv) · dv / dt = −dx / dt + (df / dv) / dv / dt = −Δv + df / dv · a, where Δv is the relative speed and a is the vehicle acceleration / deceleration. Further, in the above equation, δ represents a partial differential.

From this result, the risk w and the risk change rate d
It can be seen that w / dt is obtained from the vehicle speed v, the inter-vehicle distance x, the relative speed Δv, and the vehicle acceleration a, respectively.

Therefore, the arithmetic unit 18 uses the vehicle speed sensor 1
0, acceleration sensor, distance measuring sensor 14, Doppler sensor 1
Based on the vehicle speed v, the vehicle acceleration a, the inter-vehicle distance x, and the relative speed Δv obtained from the measurement results of 6, the risk level at that time and the rate of change dw / dt of the risk level w are calculated. In addition, in the following figures, this dw / dt is represented by adding a to the information of w.

Next, the arithmetic unit 18 obtains the certainty factor of the accelerator / brake operation when the driver feels dangerous from the obtained risk level w and the risk level change rate dw / dt by fuzzy inference.

The calculation of the certainty factor by this fuzzy inference will be described. First, FIGS. 3 and 4 show membership functions for the risk level w and the risk level change rate dw / dt, respectively. In this way, the membership function has a risk level w
B, which indicates high, medium, small, or zero (safety) depending on the value of
It is composed of four functions of M, S, and Z, and the sum of the values of B, M, S, and Z with respect to one value of w or dw / dt is always 1. There are three functions B, M, and S for the risk change rate dw / dt, but the meanings of these functions are the same, and the sum is always 1.

FIG. 5 shows a rule for calculating the certainty factor. In this way, the desired accelerator and brake operations are assigned to the combination of the risk level w and the risk level change rate dw / dt. If the risk level is Z (safe), no matter what brake or accelerator operation is performed, there is no problem, so the operation is not specified. Thus, in the rule of FIG.
When the risk change rate dw / dt with a relatively low risk is S and the risk w is S or M, and the risk change rate dw / d
In the three cases where t is M and the risk w is S, the accelerator is OFF and the brake is OFF, and the risk change rate dw / dt of the other relatively high risk is S and the risk w is
Is B, the risk change rate dw / dt is M, and the risk w is M, B
And the risk change rate dw / dt is B and the risk w is S, M, B, accelerator OFF and brake ON are assigned.

Here, the detected risk w is w0 in FIG. 3, and the detected risk change rate dw / dt is dw0.
/ Dt. In this case, the membership function values corresponding to the risk level w0 are: Z = 0, S = 0.8, M = 0.2, B = 0.

The values of the membership function corresponding to the risk change rate dw0 / dt are S = 0.6, M = 0.4 and B = 0.

Therefore, the values of the certainty factor shown in FIG. 5 for each region are as shown in FIG. That is, the value of each area is the product of the value of the membership function for the risk and the value of the membership function of the risk change rate. Therefore, the sum of the values of all areas is 1.

In this manner, the certainty factor about the driver's accelerator and brake operating conditions is calculated from the vehicle condition at that time, that is, the value of the membership function of the risk level w and the risk level change rate dw / dt.

Then, in the present embodiment, the control risk degree for controlling the alarm / automatic brake operation is based on both the certainty factor thus calculated and the actual accelerator and brake operation conditions. calculate.

Here, as shown in FIG. 7, the normal operation states of the accelerator and the brake are as follows: (X) accelerator ON.
Brake OFF, (Y) Accelerator OFF, Brake OF
There are three modes, F and (Z) accelerator OFF and brake ON. In addition, these conditions are the accelerator switch 2
4 and the signal from the brake switch 26.

That is, when the current driver's operation status is (X) accelerator ON / brake OFF, the degree of risk = accelerator OFF / brake ON certainty + 1. Therefore, in the case of FIG. 6, the risk level is 0.08 + 1 = 1.08.

(Y) When the accelerator is OFF and the brake is OFF, the degree of risk is the certainty of accelerator OFF and brake ON. Therefore, in the case of FIG. 6, the risk level is 0.08.

(Z) When the accelerator is OFF and the brake is ON, the risk is set to 0.

In this way, the vehicle control risk actually used for vehicle control is calculated. Then, the arithmetic processing device 18
Controls the alarm 20 and the automatic brake 22 based on the obtained degree of danger.

This control is performed as follows.

Risk level 0.5 to 0.8 → primary alarm (caution alarm) Risk level 0.8 to 1.2 → secondary alarm (emergency alarm) Risk level 1.2 to 2.0 → automatic Stopping the vehicle by the brake In this way, control such as an alarm can be performed based on the obtained vehicle control risk.

Now, the operation of the arithmetic processing unit 18 will be described with reference to the flowchart of FIG.

First, the vehicle speed sensor 10 and the acceleration sensor 1
2, distance measuring sensor 14, Doppler sensor 16, own vehicle speed v,
While inputting the vehicle acceleration a, the inter-vehicle distance x and the relative speed Δv, the accelerator switch 24 and the brake switch 2 are input.
ON / O of accelerator and brake by signal from 6
Input the signal for FF.

Next, the risk w is calculated from the input signal as described above (S2), and the risk change rate d is calculated.
Calculate w / dt (S3). Then, the confidence factor of each area in FIG. 6 is calculated from the obtained risk factor w and the risk factor change rate dw / dt (S4). Then, the obtained certainty factor and the accelerator switch 24 and the brake switch 26
The vehicle control risk is calculated from the accelerator and brake operating conditions obtained from the day (S5), and the warning and the brake control by the alarm 20 and the automatic brake 22 are performed based on the calculated vehicle control risk.

As described above, according to the present embodiment, the operating conditions of the accelerator and the brake by the driver are taken into consideration when calculating the risk degree for controlling the vehicle. Therefore, even if the risk calculated from the proper inter-vehicle distance according to the vehicle speed and the actual inter-vehicle distance is relatively small, the risk can be increased when the accelerator pedal is depressed. Even if the actual vehicle-to-vehicle distance is smaller than the proper vehicle-to-vehicle distance, it is likely that the driver is stepping on the accelerator and is not looking at the vehicle ahead, even if the actual vehicle-to-vehicle distance is smaller. The early warning is very effective and matches the driver's feeling. Further, when the brake has already been released, a normal alarm can be issued to provide an effective alarm. Further, when the brake is already stepped on, it is possible to prevent the generation of unnecessary alarms by prohibiting alarms and the like.

[0038]

As described above, according to the present invention,
In addition to the certainty about the accelerator / brake operation situation that is considered to be operated by the driver from the environment where the vehicle is located, consider the actual accelerator and brake operation situation. Therefore, it is possible to perform control according to the driver's situation, and control such as an alarm that suits the driver's feeling.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment.

FIG. 2 is a characteristic diagram showing a relationship between a vehicle speed v and an appropriate inter-vehicle distance x.

FIG. 3 is a characteristic diagram showing a membership function regarding a risk level w.

FIG. 4 is a characteristic diagram showing a membership function relating to a risk change rate dw / dt.

FIG. 5 is an explanatory diagram showing a rule for calculating a certainty factor.

FIG. 6 is an explanatory diagram showing an example of confidence factor calculation.

FIG. 7 is an explanatory diagram showing operation states of an accelerator and a brake.

FIG. 8 is a flowchart showing an operation of the arithmetic unit 18.

[Explanation of symbols]

 10 vehicle speed sensor 12 acceleration sensor 14 distance measuring sensor 16 Doppler sensor 18 arithmetic unit 20 alarm device 22 automatic braking device 24 accelerator switch 26 brake switch

Claims (1)

[Claims] 1. In a rear-end collision prevention device for a vehicle, a traveling condition detecting means for detecting a vehicle speed and an inter-vehicle distance to a front object, and an operating condition detecting means for detecting an operating condition of a brake and an accelerator of the own vehicle are detected. Based on the calculated risk and the change rate of risk, the risk calculating means for calculating the risk from the vehicle speed and the distance between the vehicles, the risk change rate calculating means for calculating the change rate of the risk from the change state of the risk, Then, a confidence factor calculation means for calculating a confidence factor representing the degree of the accelerator and brake operating conditions that the driver should operate in that situation, a current accelerator and brake operating condition, and an alarm / automatic alarm based on the certainty factor. A vehicle control risk calculating means for calculating a vehicle control risk for determining a vehicle operation control called a brake control, and a vehicle control risk according to the value of the vehicle control risk. Vehicle collision prevention apparatus characterized by comprising: a vehicle control means for controlling the broadcast-automatic braking, the.