JP2658582B2 - Inter-vehicle distance detection and alarm device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inter-vehicle distance detecting / warning device which detects the inter-vehicle distance between a host vehicle and a preceding vehicle, and issues an alarm when the distance falls below a certain distance. The present invention relates to an apparatus which issues an alarm at an early stage when driving at night.

[0002]

2. Description of the Related Art The causes of rear-end collisions mainly due to trucks are:
Drivers who fall asleep or drunk driving account for the majority.
Under such circumstances, an inter-vehicle distance detection / warning device has been developed which detects the inter-vehicle distance between the own vehicle and the preceding vehicle and issues a warning to the driver when the distance becomes less than a certain distance. ing. The outline of the current state of this device is that the laser beam is emitted forward from the own vehicle, the laser beam is reflected and hits the reflector on the rear surface of the front vehicle, and the laser beam is received. When the inter-vehicle distance becomes equal to or less than a predetermined distance, a buzzer in the vehicle cabin is sounded.

[0003]

It is known that the timing at which a driver depresses a brake is different between daytime and nighttime, particularly when traveling on a road such as a highway. That is, in the nighttime, the distance between vehicles generally tends to be shorter than in the daytime due to an illusion such as a visual error of the driver.

[0004] As described above, it is necessary to prevent the inter-vehicle distance from being shortened in advance to avoid danger. Also, at night, there is a possibility that the operation of depressing the brake of the driving car may be affected by drowsiness or the like.

[0005] For this reason, there is a problem that the inter-vehicle distance at which a warning is issued must be changed between daytime and nighttime.

[0006]

In order to solve the above-mentioned problems, the structure of the present invention is to detect the time required for the laser beam emitted from the own vehicle to be reflected by the preceding vehicle and return to obtain the inter-vehicle distance. An inter-vehicle distance detection / warning device that issues an alarm when the inter-vehicle distance becomes smaller than a predetermined distance determined based on the own vehicle's braking distance or idle running distance .
Vehicle distance D is the vehicle braking distance L ₃ = Vf ² / 2α ₁ and the vehicle empty
From the sum of the running distance L ₂ = (Td + Tx) Vf, the braking distance of the front vehicle
The safe inter-vehicle distance Ds obtained by subtracting L ₁ = Va ² / 2α ₂
Equation D triggered by the time the remote becomes smaller ^{_{<Vf 2 / 2α 1 + (}} Td + Tx) Vf-Va 2 / 2α 2 = Ds However, Td: vehicle empty run time, Tx: determination time, Vf: own The vehicle speed, Va: the front vehicle speed, α ₁ : own vehicle deceleration, α ₂ : front vehicle deceleration are satisfied, and the lighting switch is turned on.
Change the value of the judgment time Tx
The distance between vehicles Ds is changed.
You.

[0007]

According to the above inter-vehicle distance detection / warning apparatus, the setting of the distance at which the warning is issued is changed according to whether the traveling condition determined based on the detection result of the environment sensor is daytime or nighttime. In addition, even at night, proper traveling can be performed without delay of generation of an alarm.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an apparatus configuration of an embodiment of an inter-vehicle distance detecting / warning apparatus according to the present invention, and FIG.

Reference numeral 1 denotes a laser radar unit having a light emitting unit 2 and a light receiving unit 3. FIG. 3 shows the configuration of the laser radar unit 1.

The light receiving section 2 includes a laser diode driving circuit 4, a laser diode 5, and a light emitting lens 6, and emits a laser beam in a pulsed manner at regular intervals. The light receiving section 3 includes a light receiving lens 7, which receives laser light reflected by a reflector of a front vehicle, a photodiode 8, an amplifier 9, a signal processor 10, and the like. The inter-vehicle distance D is detected by the distance detection circuit 11 based on the time difference Δt between the light emission by the light emitting unit 2 and the light reception by the light receiving unit 3.
(= Δt / 2 × speed of light).

An inter-vehicle distance signal which is a detection value of the laser radar unit 1 is input to a control unit 14 incorporated below the seat 13 of the truck 12.

The laser radar unit 1 is assembled in a bumper 15 of a truck 12 as shown in FIG.
In this embodiment, three light emitting units 2 and three light receiving units 3 are provided,
As shown in FIG. 4, three laser beams 16 are located on the left, center, and right.
a, 16b, and 16c.

Reference numeral 17 denotes a vehicle speed sensor which detects a vehicle speed from a rotating portion of the transmission or the like. The detection signal of the vehicle speed sensor 17 is input to the control unit 14.

Reference numeral 18 denotes a disk 19 provided on the steering column and a light emitting / receiving unit 20 for detecting the slits.
And a steering angle signal which is a detection signal thereof is input to the control unit 14.

Reference numeral 23 denotes a wiper switch that functions as an example of an environment sensor, and reference numeral 25 denotes a lighting switch that functions as another example of the environment sensor. ON, O
The FF signal is input to the control unit 14. In other words, when the wiper switch 23 is turned on, it is determined that it is raining, and the lighting switch 2 is turned on.
When 5 is turned on, it is determined that it is nighttime.

The other environmental sensors 24 include a raindrop sensor, a road surface sensor, a temperature sensor, a slip sensor, and the like. According to the raindrop sensor, it is detected that it is rainy, that is, the road surface is in a wet state, and according to the road surface sensor, it is detected whether the road surface is a bumpy road or other conditions, and according to the temperature sensor, The weather and thus the road surface condition, for example, a frozen state, are detected in combination with the detection results of other sensors. According to the slip sensor,
From the rotational speed difference between the front wheels and the rear wheels, it is detected whether the road surface is likely to slip, that is, whether it is a low μ road or a high μ road. The detection result is input to the control unit 14.

Reference numeral 21 denotes a display unit incorporated in the instrument panel in front of the driver's seat, which is provided with a display unit for the distance between vehicles, a buzzer that issues an alarm, a lamp that flashes when an alarm is generated, and the like to call the driver's attention. It also warns you.

Next, a description will be given of a calculation process leading to the generation of an alarm by the apparatus of the embodiment.

The distance between the host vehicle 12 and the front vehicle 22, that is, the inter-vehicle distance D (m) is determined by the laser radar unit 1 as described above.
Required by The vehicle speed Vf (m / s) is calculated by the vehicle speed sensor 1
7 is detected. The speed Va (m / s) of the front vehicle 22 is obtained by calculation from a change in the inter-vehicle distance D per minute time.

On the other hand, the time required for the driver to depress the brake pedal after determining that it is dangerous, that is, the idle running time Td (S), the time when the driver determines that it is dangerous, that is, the determination time Tx (s) and the vehicle deceleration α ₁ (m / s ²⁾ and preceding vehicle deceleration α ^₂ (m / s ₂₎ is stored in the memory in advance the control unit 14. As the decelerations α ₁ and α ₂ , values assuming full braking are stored, and normally, α ₁ = α ₂ .

The braking distance L ₁ of the front vehicle 22 is determined from the preceding vehicle speed Va and the deceleration α ₂ by L ₁ = Va ² / 2α ₂ .

The free running distance L ₂ of the own vehicle 12 is equal to the own vehicle speed Vf.
From the idle running time Td and the judgment time Tx, L ₂ = (Td +
Tx) It is determined by Vf.

The braking distance L ₃ of the own vehicle 12 is equal to the own vehicle speed Vf.
And obtained from the deceleration alpha ₁ Metropolitan by ^{_{L 3 = Vf 2 / 2α 1}} .

Therefore, the condition for generating an alarm is that the sum of the preceding vehicle braking distance L ₁ and the following distance D is equal to the own vehicle braking distance L _3.
Triggered by the when and becomes smaller than the sum of the vehicle air-run distance L _2. That is, Va ² / 2α ₂ + D <Vf ² / 2α ₁ + (Td + Tx) Vf

Therefore, D <(Td + Tx) Vf + (Vf ² / 2α ₁ −Va ² / 2α)
₂ ) When Ds (safety inter-vehicle distance), an alarm is issued from the display unit 21 and the lamp blinks.

However, in night driving on a highway or the like, it is necessary to further prevent danger. Therefore, when it is detected that the lighting switch 25 is turned on, the control unit 14 changes the value of the determination time Tx for calculating the safe inter-vehicle distance Ds, and changes the value to the longer safe inter-vehicle distance Ds for night. I do.

Next, a specific example of control by the control unit 14 in the present embodiment will be described with reference to the flowchart of FIG. First, an initial value is set in step (1). That is, the idle running time Td and the determination time T
x, decelerations α ₁ and α ₂ (α ₁ = α ₂ ) of the own vehicle 12 and the front vehicle 22 at the time of full braking are set.

While the truck 12 is running, the inter-vehicle distance D is calculated in step (2) based on the above formula, and in step (3), the vehicle speed Vf is detected by the vehicle speed sensor 17, and the vehicle speed Vf is detected in step (4). In), the preceding vehicle speed Va is obtained from the change in the inter-vehicle distance D and the own vehicle speed Vf.

Next, when the lighting switch 25 is turned on,
Change the value of judgment time Tx by turning OFF or step (5)
The safe inter-vehicle distance Ds is calculated based on one of the values of the determination time Tx, the detection result, and the calculation result (step (6)).

Next, in step (7), it is determined whether or not the current inter-vehicle distance D is within the safe inter-vehicle distance Ds. If it is within the safe inter-vehicle distance Ds, the process proceeds to step (8), no alarm is generated, and only the inter-vehicle distance is displayed on the display unit 21.

If it is determined in step (7) that the inter-vehicle distance D is smaller than the safe inter-vehicle distance Ds, the process proceeds to step (7).
In (9), the preceding vehicle speed Va is compared with the own vehicle speed Vf. When the preceding vehicle speed Va is high, the warning is not required to be issued because the inter-vehicle distance D is increasing, and the process proceeds to step (8). When the preceding vehicle speed Va is lower than the own vehicle speed Vf, the vehicle is in a region to be warned and is gradually approaching. Accordingly, the display unit 21 is instructed to generate an alarm, an alarm is issued in step (10), and the inter-vehicle distance D is displayed.

The above calculation is repeated while the truck 12 is running.

As described above, the warning is generated or not based on the comparison between the safe inter-vehicle distance Ds and the inter-vehicle distance D. However, the alarm can be generated stepwise. .

For example, when D <Ds, a buzzer sounds several times as a primary alarm (caution alarm).
The secondary alarm ^{D <TdVf + (Vf 2 /} 2α 1 -Va 2/2
α ₂ ) = Ds _{1. In} this case, the buzzer continuously sounds. In this state, the driver does not need to make a decision, but needs to immediately depress the brake. If the warning is gradual, the driver's response will be quicker.

Although the above embodiment does not take into account road surface conditions and the like, it may take into account the detection results of the environmental sensors 23 and 24 and the like.

[0036]

According to the inter-vehicle distance detecting / warning apparatus of the present invention, the inter-vehicle distance for issuing a warning is switched between daytime and night, so that a longer inter-vehicle distance can be taken at night. , Safer driving will be ensured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an apparatus configuration according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a schematic positional relationship between components.

FIG. 3 is an explanatory diagram of a laser radar unit.

FIG. 4 is a plan view showing a state in which a laser beam starts.

FIG. 5 is an explanatory diagram of an inter-vehicle distance, a braking distance, and the like.

FIG. 6 is a flowchart of an embodiment.

[Explanation of symbols]

 Reference Signs List 1 laser radar unit 12 own vehicle 14 control unit 16a, 16b, 16c light beam 17 vehicle speed sensor 18 steering sensor 19 wiper switch 21 display unit 25 lighting switch

Claims (1)

(57) [Claims] An inter-vehicle distance is determined by detecting a time until a laser beam emitted from the own vehicle is reflected by a preceding vehicle and returned, and the inter-vehicle distance is determined based on a braking distance and an idle running distance of the own vehicle. In an inter-vehicle distance detecting / warning apparatus which issues an alarm when the distance becomes smaller than a predetermined distance set in the above, the alarm is issued when the inter-vehicle distance D is equal to the own vehicle braking distance L ₃ = Vf ² / 2α _1.
From the sum of the vehicle's free running distance L ₂ = (Td + Tx) Vf
Vehicle braking distance L ₁ = Safe inter-vehicle distance less Va ² / 2α ₂
The following equation D <Vf ² / 2α ₁ + (Td + Tx) Vf−Va ² / 2α ₂ = Ds triggered when the distance becomes smaller than Ds, where Td: free running time of the vehicle, Tx: determination time, Vf : The vehicle speed, Va: the speed of the preceding vehicle, α ₁ : the deceleration of the vehicle, α ₂ : the deceleration of the preceding vehicle, and it was detected that the lighting switch was turned on.
The safe inter-vehicle distance Ds by changing the value of the judgment time Tx
Inter-vehicle distance detection and warning
Information device.