JPH06162400A - Warning device for approaching preceding car - Google Patents

Abstract

PURPOSE:To enhance driver's attention and to prevent a rear-end collision by calculating the change rate of time between cars and sending warning basing on the change rate. CONSTITUTION:The device is provided with a car-speed detection means 1 which detects the travelling speed, distance-between-cars detection means 2 detecting the distance between cars, time-between-cars calculating means 3 calculating the time between cars basing on the distance between cars and the travelling speed, time-between-cars change rate calculation means 4 calculating the time change rate of the time between cars, warning judgement means 5 judging the degree of approaching the preceding car basing on the change rate and outputting a warning command, and warning generation means. In the means 3, the distance between cars from the own vehicle to the preceding car is divided by the car speed to calculate the time between cars. Basing on this, the means 4 obtains the change rate of time between cars. When the means 5 judges the danger of collision is increased basing on the degree of change rate, a warning is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an approaching vehicle approach warning system for issuing a warning to a driver when there is a possibility of a rear-end collision.

[0002]

2. Description of the Related Art As a conventional warning device for approaching a preceding vehicle of this type, there is, for example, one disclosed in Japanese Utility Model Laid-Open No. 15282282. This is to output forward while sweeping electromagnetic waves such as laser light toward the front of the vehicle, receive reflected waves of the electromagnetic waves, detect the distance R to the reflector from the propagation delay time from output to reception, and set the reference value. The warning is issued when the distance is shorter than the inter-vehicle distance which may cause a rear-end collision. And here, if the driver is driving with a distance between the vehicles that is considered safe according to his / her own judgment, or if he is intentionally approaching until just before to overtake, comfortable driving The alarm is divided into two stages so that the driver's attention to the alarm is not reduced by the excessive alarm and the effect of alerting to the rear-end collision, which is the original purpose of the alarm, is not diminished without disturbing the condition.

That is, the first inter-vehicle distance R is used as a reference value.
s1 and a second inter-vehicle distance Rs2, which is smaller than this and is too dangerous when approaching more than this value, is provided. When the detected inter-vehicle distance R becomes Rs1 or less, a first alarm is issued for a certain period of time. When the inter-vehicle distance Rs2 becomes 2, the second alarm is continuously generated.
By the way, the first inter-vehicle distance R that may cause the above-mentioned rear-end collision.
s1 is determined as follows from the vehicle speed Va of the host vehicle and the idle time Td.

[Equation 1]

[0004]

However, in the above-mentioned conventional alarm device, the information given to the driver regarding the degree of risk of a rear-end collision is only two points of information regarding the inter-vehicle distance, and the change in the degree of risk is In particular, the problem remains that the driver cannot be made aware of the situation where the degree of danger is increasing. For example, even after the warning of the first stage is issued, even if the risk increases, the driver cannot be notified of the increased risk until the second stage. Similarly, even if the second-stage warning is issued and the risk of a rear-end collision is further increased, the warning means is the same, so that the driver is distracted due to sideways driving or dozing driving. Then, there is a problem that the driver's attention is not attracted. Therefore, the present invention
In view of the above-mentioned conventional problems, it is an object of the present invention to provide a preceding vehicle approach warning device that surely notifies when the approach situation to the preceding vehicle tends to increase the risk of a rear-end collision.

[0005]

[Means for Solving the Problems] Then, considering the behavior of the vehicle, when the preceding vehicle suddenly decelerates while following the vehicle while maintaining a certain inter-vehicle distance, The time required for the vehicle to reach the current position of the preceding vehicle, that is, the inter-vehicle time changes, for example, as shown in FIG. Here, the inter-vehicle time is obtained by dividing the inter-vehicle distance by the relative speed between the own vehicle and the preceding vehicle. When the driver's attention is normal and the vehicle is in a normal driving state, as shown by the broken line, braking operation is performed to maintain the following distance according to the change in vehicle speed so that the following time does not change so much. The change rate of the inter-vehicle time is small until the inter-vehicle time increases rapidly due to the stop of the own vehicle.

However, when the driver is in an abnormal state in which the driver's attention is reduced due to a sideways or drowsiness driving state, he / she does not notice the deceleration of the preceding vehicle, and the inter-vehicle time decreases rapidly as indicated by the solid line. If recovery measures are not taken, the inter-vehicle time becomes zero and the vehicle in front will collide with the preceding vehicle. When the inter-vehicle distance warning of the conventional device in this abnormal state is drawn back to the inter-vehicle time, it is expressed as shown in FIG. Here, the conversion to the inter-vehicle time is obtained by dividing the reference inter-vehicle distances Rs1 and Rs2 by the vehicle speed, and is expressed as follows.

[Equation 2]

[Equation 3] Then, the inter-vehicle time Th at a certain moment is compared with the reference inter-vehicle time, the first alarm is issued when the first alarm inter-vehicle time Ths1 or less, and the second alarm is issued when the second alarm inter-vehicle time Ths2 is reached. become. However, it can be seen that the risk of a rear-end collision has already increased from the reduction degree β of the inter-vehicle time before the second alarm is issued.

Therefore, as shown in FIG.
If a warning is given when the rate of change in inter-vehicle time ΔTh shows a decreasing tendency of inter-vehicle time above a predetermined level, the driver is informed of the situation that the risk of a rear-end collision is increasing without losing the timing. Can be made. At the same time, the alarm can be stopped if the driver makes a correction operation and the rate of change in the inter-vehicle time is improved, so that it is possible to avoid bothering the driver for a long time with an unnecessary alarm.

Therefore, according to the present invention, as shown in FIG. 3, the vehicle speed detecting means 1 for detecting the traveling speed of the own vehicle and the inter-vehicle distance detecting means 2 for detecting the inter-vehicle distance between the own vehicle and the preceding vehicle.
And an inter-vehicle time calculating means 3 for calculating an inter-vehicle time based on the inter-vehicle distance and the traveling speed, an inter-vehicle time change rate calculating means 4 for calculating a time change rate of the inter-vehicle time, and a preceding step based on the inter-vehicle time change rate. An alarm determination means 5 for determining the degree of approach to the vehicle and outputting an alarm command, and an alarm generation means 6 for issuing an alarm based on the alarm command are provided.

[0009]

In the inter-vehicle time calculating means 3, the inter-vehicle time Th is calculated by dividing the inter-vehicle distance R from the own vehicle to the preceding vehicle by the vehicle speed Va.
(= R / Va) is calculated. Based on this, the inter-vehicle time change rate calculating means 4 obtains the inter-vehicle time change rate ΔTh, and ΔT
When the alarm determination means 5 determines that the risk of a rear-end collision is increasing due to the size of h, an alarm is issued. As a result, the driver is informed of the increasing tendency of the risk of a rear-end collision before the second warning is issued when the degree of danger is extremely high.

[0010]

FIG. 4 is a block diagram showing the configuration of an embodiment of the present invention. The radar device 21 transmits an electromagnetic wave toward the front of the vehicle, receives a reflected wave from the preceding vehicle, and detects the inter-vehicle distance R to the preceding vehicle based on the propagation delay time from transmission to reception. Appropriate electromagnetic waves such as laser light and radio waves are selected as the electromagnetic waves. A vehicle speed sensor 23 that detects the vehicle speed Va of the host vehicle is provided, and detection signals from the vehicle speed sensor 23 and the radar device 21 are input to the information processing circuit 25. The alarm generation device 27 is activated by an alarm command from the information processing circuit 25.

The information processing circuit 25, based on the vehicle speed Va and the inter-vehicle distance R, the inter-vehicle time Th and the change rate ΔTh of the inter-vehicle time.
Is calculated and the risk of a rear-end collision with the preceding vehicle is determined. When the risk of a rear-end collision is high or the risk increases, an alarm command is output to the alarm generator 27. The warning inter-vehicle distance as a reference for the primary warning that indicates the possibility of a rear-end collision is

[Equation 4] In addition, as a reference for the secondary alarm, an inter-vehicle distance Rs2 is set that is too dangerous as the absolute value is further approached.

The alarm generation device 27 changes its alarm mode in response to an alarm command. That is, for example, a yellow caution warning lamp is used as a primary warning indicating the possibility of a rear-end collision, and a red emergency warning lamp is used as a secondary warning when the degree of danger is high. Then, in order to indicate that these warnings have started, a caution warning sound is added to the primary warning, and an emergency warning sound having a pitch higher than that of the caution warning sound is added to the secondary warning for a fixed time. Then, in addition to the above-described primary and secondary alarms, an inter-vehicle time change alarm is set.

Next, the flow of processing in the information processing circuit 25 is shown in the flow charts of FIGS. First, in step 101, the inter-vehicle distance R from the radar device 21
The vehicle speed Va from the vehicle speed sensor 23 is read, and the rate of change of the inter-vehicle distance R is calculated using the method of least squares or the like in step 102 to obtain the relative speed Vs of the host vehicle and the preceding vehicle. In the next step 103, the relative speed Vs and the vehicle speed Va are compared. This is to check whether the preceding vehicle is stopped.

When -Vs is almost equal to Va, it is judged that the preceding vehicle is stopped, and the routine proceeds to step 104, where the risk of a rear-end collision is judged. At this time, the primary alarm standard is

[Equation 5] This is regarded as the secondary warning standard when the preceding vehicle is stopped. When Rs1 ′ ≧ R holds, the risk of a rear-end collision is high,
After step 105, the process proceeds to step 106. In step 106, an alarm command that outputs an emergency alarm sound is output as a secondary alarm for high risk. Then, subsequently in step 107, an alarm command for turning on the emergency alarm lamp is output.

In step 105, while this state continues, the elapsed time from the time TF2 when the alarm is first issued to the current time Tn is checked, and if it is within the predetermined alarm time Δt, the emergency alarm sound is generated. If the alarm time Δt is exceeded, the process proceeds to step 108 to stop the emergency alarm sound, and only the emergency alarm lamp is continuously turned on.

On the other hand, if -Vs is not equal to the vehicle speed Va of the host vehicle in step 103, that is, if it is determined that the preceding vehicle is running, the process proceeds to step 110.
The possibility of a rear-end collision is determined. The determination here is performed by checking whether the inter-vehicle distance R is equal to or less than the primary alarm standard that requires attention by the following formula. Rs1 ≧ R

If this equation holds, step 11
In 1, the inter-vehicle distance R is further compared with the more dangerous secondary warning distance Rs2. If the inter-vehicle distance R is less than or equal to the secondary warning distance Rs2, the process proceeds to the secondary warning process after step 105.

When the inter-vehicle distance R is larger than the secondary warning distance Rs2, the processing proceeds to step 113 through step 112 as the primary warning processing. In step 113, a warning command for issuing a caution warning sound is output as a primary warning indicating the possibility of a rear-end collision. Then, subsequently in step 114, an alarm command for turning on the caution alarm lamp is output. Steps 112 and 115 limit the duration of the caution alarm sound, and the start of measurement is the primary alarm start time point TF1, and step 1 in the secondary alarm process.
The processing is the same as that of 05 and 108.

After the above-mentioned primary alarm processing or secondary alarm processing, the routine proceeds to step 120, where the inter-vehicle time Th is calculated. Th is calculated by the following equation. Th = R / Va Next, at step 121, the change rate ΔTh of the inter-vehicle time Th is obtained. Here, it is calculated by the following equation. In addition, the least squares method can be used to obtain the change rate. ΔTh = Th−Th0 where Th is the current inter-vehicle time and Th0 is the inter-vehicle time before a certain time.

Thereafter, in step 122, the change rate ΔTh of the inter-vehicle time is compared with a negative predetermined value ΔTx. When ΔTh is equal to or less than ΔTx, the reduction rate of the inter-vehicle time is large, and it is determined that the driver is abnormal such as a sideways drive, a drowsiness state, or a delay in operation reaction.
23, an alarm command for generating an inter-vehicle time change alarm sound is output to the alarm generation device 27. The inter-vehicle time change alarm sound is, for example, an alarm sound that repeats a pitch change from a low frequency range to a high frequency range, and is easily distinguishable from the caution alarm sound and the emergency alarm sound. Then, the process returns to step 101 and the above process is repeated. Also, if the determination formulas are not satisfied in step 104 or step 110, the process returns to step 101.

By the above processing, an alarm corresponding to the change in the inter-vehicle time is generated in the mode shown in FIG. In the figure, (a) shows the change situation of the inter-vehicle time, and (b) and (c) show the primary and secondary alarms, respectively.
(D) shows an inter-vehicle time change alarm based on the inter-vehicle time change rate of (e). In FIG. 7, the warning distances Rs1 and Rs2 are replaced with inter-vehicle times Ths1 and Ths2 as the primary and secondary alarm criteria, respectively.

When the inter-vehicle time is changing due to, for example, deceleration of the preceding vehicle, first the inter-vehicle time Th is the primary reference Ths.
When it becomes 1 or less, the primary alarm sound is generated and the primary alarm lamp is turned on. This primary warning lamp is, for example, a yellow lamp as described above. After that, after the lapse of time Δt, the primary alarm sound is stopped, and only the primary alarm lamp is continuously lit.

Next, when the change rate ΔTh of the inter-vehicle time exceeds the reference change rate shown in FIG. 7 (e), the inter-vehicle time change alarm sound is emitted. This inter-vehicle time change warning sound is ΔT
As long as h is equal to or lower than the reference rate of change, it is continuously continued. After a further lapse of time, the value of the inter-vehicle time Th changes to the secondary reference Ths.
When it becomes 2 or less, the secondary alarm sound is generated and the secondary alarm lamp is turned on. As with the primary alarm, this secondary alarm sound is also stopped after the lapse of time Δt, but the secondary alarm lamp, which is red, for example, remains lit.

The present embodiment is configured as described above, and primary and secondary alarms of different levels are given at two predetermined vehicle-to-vehicle distances, and the risk of rear-end collision is increased based on the rate of change in vehicle-to-vehicle time. The vehicle-to-vehicle time change warning is issued while the vehicle is in the middle of a vehicle, so the risk of a rear-end collision may increase without waiting for the secondary warning when the danger level becomes extremely high after the primary warning. The danger of a rear-end collision can be effectively avoided even when the driver is informed earlier and the driver's attention is distracted, such as dozing or looking aside.

The primary and secondary alarms are respectively provided by alarm lamps to which an alarm sound is added. When the alarm lamp continues to light, the alarm sound is suppressed for a limited time and continued for a long time. It prevents the alertness from becoming weak or bothersome to the driver. Further, since the primary and secondary alarms and the inter-vehicle time change alarm respectively use different pitches and colors, they have an effect that they are easily identified and the degree of risk is surely recognized by the driver. The primary and secondary alarms can be set to the inter-vehicle time instead of the inter-vehicle distance as shown in the replacement display in FIG. 7. In this case, in the above-mentioned flowchart, the vehicle speed Va and the inter-vehicle distance can be set. The inter-vehicle time Th may be calculated immediately after reading R.

[0026]

As described above, according to the present invention, the change rate of the inter-vehicle time is calculated, and the alarm is issued based on the change rate. Therefore, the mere inter-vehicle distance and inter-vehicle time are fixedly set. In addition to the warning based on the warning standard, when the risk of a rear-end collision is increasing, this can be detected and immediately notified, and an effect is provided that the timing is not lost. In addition, especially when used together with an alarm based on the distance between vehicles or time between vehicles, and when the alarm mode is changed, the alerting power is large even when the driver's attention is distracted, such as when he / she falls asleep or while driving aside. ,
A great effect is exhibited by preventing a rear-end collision.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a behavior of a vehicle during follow-up running of a preceding vehicle.

FIG. 2 is an explanatory diagram showing the principle of the present invention.

FIG. 3 is a block diagram showing a configuration of the present invention.

FIG. 4 is a block diagram showing a configuration of an exemplary embodiment of the invention.

FIG. 5 is a flowchart showing processing in the information processing circuit according to the embodiment.

FIG. 6 is a flowchart showing processing in the information processing circuit according to the embodiment.

FIG. 7 is a time chart showing a situation of alarm generation in the embodiment.

[Explanation of symbols]

 1 vehicle speed detection means 2 inter-vehicle distance detection means 3 inter-vehicle time calculation means 4 inter-vehicle time change rate calculation means 5 alarm determination means 6 alarm generation means 21 radar device 23 vehicle speed sensor 25 information processing circuit 27 alarm generation device Va vehicle speed R inter-vehicle distance Th inter-vehicle distance Time ΔTh Change rate of inter-vehicle time

Claims (4)

[Claims] 1. A vehicle speed detecting means for detecting a traveling speed of the own vehicle, an inter-vehicle distance detecting means for detecting an inter-vehicle distance between the own vehicle and a preceding vehicle, and an inter-vehicle time calculated based on the inter-vehicle distance and the traveling speed. Inter-vehicle time calculating means, inter-vehicle time change rate calculating means for calculating the time change rate of the inter-vehicle time, and alarm determination means for determining the degree of approach to the preceding vehicle based on the inter-vehicle time change rate and outputting an alarm command. And a warning signal generating means for issuing a warning based on the warning command. 2. The alarm determination means issues an alarm command when the inter-vehicle time or inter-vehicle distance is a predetermined value or less and the absolute value of the inter-vehicle time change rate is a predetermined value or more in a direction in which the inter-vehicle time decreases. The preceding vehicle approach warning device according to claim 1, wherein the preceding vehicle approach warning device is provided. 3. The alarm determination means issues a first alarm command when the inter-vehicle time or inter-vehicle distance is below a predetermined value, the inter-vehicle time or inter-vehicle distance is below a predetermined value, and the inter-vehicle time decreases. Direction, the second alarm command is issued when the absolute value of the inter-vehicle time change rate is equal to or greater than a predetermined value, and the alarm generation means issues different alarms corresponding to the first alarm command and the second alarm command. The preceding vehicle approach warning device according to claim 1, which is issued. 4. The preceding vehicle approach warning according to claim 3, wherein the warning corresponding to the first warning command is a visual warning, and the warning corresponding to the second warning command is an auditory warning. apparatus.