JP2830577B2 - 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 apparatus which detects the inter-vehicle distance between a host vehicle and a preceding vehicle and issues an alarm when the distance becomes smaller than a safe inter-vehicle distance. Buzzer when there is an interrupted car while driving on the road
To prevent frequent alarms and prevent sudden braking of interrupted vehicles.
To reliably prevent rear-end collisions .

[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 that currently detects the inter-vehicle distance between the host vehicle and the preceding vehicle and issues an alarm to the driver when the distance falls below a certain safe inter-vehicle distance. Is being developed. The outline of the current state of this device is that the laser beam is emitted forward from the own vehicle, the laser beam that hits the reflector on the rear surface of the front vehicle is received, and the inter-vehicle distance is calculated from that time. When the inter-vehicle distance becomes equal to or less than the safe distance, a buzzer in the vehicle compartment sounds.

[0003]

In the above-mentioned conventional apparatus, if there is an interrupted vehicle, an alarm is issued by a buzzer in most cases, which leads to a frequent occurrence of alarms, which rather deteriorates the feeling of the occupants. Was. In other words, for example, vehicles are generally running smoothly on expressways, so it is extremely rare that sudden braking is performed even if another vehicle interrupts in front of the own vehicle. It is.

[0004]

In order to solve the above-mentioned problems, the present invention detects the time until the laser beam emitted from the own vehicle is reflected by the preceding vehicle and returns to obtain the inter-vehicle distance. In an inter-vehicle distance detection / warning device that issues an alarm when the inter-vehicle distance becomes smaller than the safe inter-vehicle distance, it is determined whether or not the interrupted vehicle is present and whether or not the own vehicle speed is equal to or higher than a predetermined speed. When the vehicle speed is equal to or higher than a predetermined speed , the distance between vehicles (D) is the second warning safety vehicle
Safety inter-vehicle distance for the first warning above the inter-vehicle distance (D _S2 )
Ramp when the vehicle speed is less than (D _S1 ) and the vehicle speed is faster than the front vehicle speed
Only an alarm (S12) is issued and the inter-vehicle distance (D) is
If the vehicle speed is less than the safety inter-vehicle distance (D _S2 ) for warning,
An inter-vehicle distance detection / warning apparatus characterized by issuing a warning of a lamp and a buzzer (S14) at a faster speed .

[0005]

When the vehicle is traveling at a predetermined speed, for example, 60 km / h or more, there is an interrupted vehicle and the inter-vehicle distance (D) is set to the second order.
The first safety car for safety when the safety inter-vehicle distance ( _DS2 ) is exceeded
<br/> time between distance (D _S1) and less than the host vehicle speed is higher than the preceding vehicle speed is determined to be traveling on a highway or the like smoothly, La
(Step S12 in FIG. 6).
See). That is, the buzzer alarm is not issued so that the driver does not feel unnecessary troublesomeness. Hand, car
Inter-vehicle distance (D ) is less than the secondary warning safe inter-vehicle distance (D _S2 )
When the own vehicle speed is faster than the front vehicle speed,
Alarm for the lamp and buzzer (step S in FIG. 6).
14). Therefore, it is not possible to issue a warning only for the lamp.
Even if the vehicle in front suddenly brakes,
A buzzer alarm is issued in addition to the alarm to prevent rear-end collision.
I can. However, if the own vehicle speed is lower than the predetermined speed, it can be determined that the vehicle is traveling on a general road or a congested highway, and a warning is immediately issued because the preceding vehicle may perform sudden braking due to a signal or a traffic jam after an interruption. .

[0006]

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, and a light emitting unit 2
And a light receiving unit 3. FIG. 3 shows the configuration of the laser radar unit 1. The light emitting 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 short fixed time 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 (= Δt / 2) × light speed is obtained by the distance detection circuit 11 from the time difference Δt between the light emission by the light emitting unit 2 and the light reception by the light receiving unit 3. 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 the bumper 15 of the truck 12 as shown in FIG. 2. In this embodiment, the laser radar unit 1 includes three light emitting units 2 and three light receiving units 3, and as shown in FIG. Three laser beams 16a, 16b, 16c are emitted to the center and right. FIG. 5 shows the relationship between the host vehicle 12 and the front vehicle 22.

Reference numeral 17 denotes a vehicle speed sensor which detects the vehicle speed Vf (m / s) 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. Front car 2
The speed Va (m / s) of the second control unit 14
From the change in the inter-vehicle distance D per minute time. That is, the front vehicle speed Va is obtained from the relative speed between the own vehicle 12 and the front vehicle 22.

In the present embodiment, the control unit 14 determines whether or not the intervening vehicle has changed by 10 m or more and this state has continued for 0.5 second or more. It is determined that there is an interrupted car.

The control unit 14 compares the vehicle speed Vf with a predetermined speed _VH (m / s) corresponding to, for example, 60 km / h. If Vf ≧ _VH , the control unit 14 determines that the vehicle is traveling on the highway. If Vf < _VH , it is determined that the vehicle is traveling on a general road.

Next, regarding the safe inter-vehicle distance Ds, in this embodiment, the warning is performed in a stepwise manner, so that the judgment time T during braking is determined.
x and the idling time Td are both taken into consideration, and the primary warning safety inter-vehicle distance D _S1 and the second warning safety vehicle distance D _S2 taking into account only the idling time Td except for the stricter judgment time Tx. Are set by the control unit 14 by calculation. Specifically, it is as follows. [Primary warning safe inter-vehicle distance D _S1 ] Time from when the driver determines that the vehicle is dangerous to when the driver depresses the brake pedal, that is, idle running time Td (s), and when the driver determines that the vehicle is dangerous, that is, determination time tx (s) and deceleration alpha ₁ of the vehicle (m / s ²⁾ and preceding vehicle deceleration α ^₂ (m / s ₂₎ is stored in the memory in advance the control unit 14. Deceleration α ₁ , α ₂
Is a value assuming full braking, and normally α ₁
= Is the α _2. Braking distance of the preceding vehicle 22 L ₁ is determined by L ₁ = Va _² / ^{α 2} from the preceding vehicle speed Va and the deceleration alpha ₂ Prefecture. The free running distance L ₂ of the own vehicle 12 is obtained from the own vehicle speed Vf, the free running time Td, and the determination time Tx, by L ₂ = (Td + Tx).
It is determined by Vf. Braking distance L ₃ of the vehicle 12 is determined by L ₃ = Vf ² / 2α ₁ from deceleration alpha ₁ Tokyo between the vehicle speed Vf. Therefore, the conditions of the primary alarm, preceding vehicle braking distance L ₁ and the automatic braking the sum of the inter-vehicle distance D distance L ₃
Triggered by the when and becomes smaller than the sum of the vehicle air-run distance L _2. In other words, 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 ) = _DS1 (safety inter-vehicle distance). As a primary alarm, a buzzer is intermittently blown several times and a lamp is blinked. [Secondary inter-vehicle safety inter-vehicle distance D _S2 ] As a condition for the occurrence of the second alarm, the sum of the preceding vehicle braking distance L ₁ and inter-vehicle distance D is equal to the sum of the self-vehicle braking distance L ₃ and the judgment time Tx. Triggered when it becomes smaller than the sum of the vehicle running distance (Td · Vf). That is, D <Td · Vf + (Vf ² / 2α ₁ −Va ² / 2α ₂ ) = D
_S2 (safety distance). In the case of this secondary alarm, the buzzer sounds continuously. In other words, 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.

In FIG. 1, reference numeral 21 denotes a display unit incorporated in an instrument panel in front of a driver's seat, which is provided with a display unit for an inter-vehicle distance, a buzzer that issues an alarm, a lamp that flashes when an alarm is generated, and the like. Instructs the driver to pay attention and gives a warning. The display of the inter-vehicle distance is always performed.

By the way, on a wet road surface or in freezing in rainy weather
Vehicle deceleration α₁, Α_TwoBecomes smaller.
Therefore, Wipass switch, which functions as an example of an environmental sensor,
Switch 23, and its ON and OFF signals are
The data is input to the knit 14. That is,
Judgment of rainy weather by turning on Ipa switch 23
You do it. That the wiper switch 23 has been turned on
If detected, the control unit 14
Deceleration α₁, Α_TwoThe safe distance between vehicles by changing the value of
You. In other words, on a wet road surface, etc., the safe inter-vehicle distance D
_S1, D_S2Changes, and the alarm generation time is advanced.
You. For example, deceleration α on a dry road₁(= Α _Two) Is 0.3
If it is about G, 0.2G (e.g.,
0.1G (for example, frozen roads, snowy roads)
Etc.).

The other environment sensors 24 include a raindrop sensor, a road surface sensor (G 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,
The road surface sensor detects whether the road surface is a gravel road or other conditions, and the temperature sensor detects the weather and the road surface condition, for example, a frozen state, in combination with the detection result of another sensor. According to the slip sensor, it is detected from the rotational speed difference between the front wheels and the rear wheels whether or not 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 output to the control unit 14.

As described above, in this embodiment, since the primary alarm and the secondary alarm are introduced, the control unit 14
Is roughly controlled as follows (1) to (4). (1) Secondary warning: D < _DS2 and higher than the preceding vehicle, regardless of the presence or absence of an interrupting vehicle, and regardless of Vf ≧ _VH (highway driving) and Vf < _VH (general road driving). Also, when the vehicle is fast (Va <Vf), the buzzer is continuously sounded and the lamp is turned on as a secondary alarm to prompt the driver to immediately perform quick braking. (2) Primary alarm: When there is no interrupted vehicle, regardless of the traveling road, or when there is an interrupted vehicle, V
D _S2 ≦ D <D only when f <V _H (during general road driving)
_{When S1} and Va <Vf, the buzzer sounds several times and the lamp blinks as a primary alarm to urge the driver to judge whether or not sudden braking is necessary. (3) Buzzer stop of primary alarm: Interruption vehicle is present and V
when f ≧ V _H (highway) only, if the D _S2 ≦ D <D _S1 and Va <Vf, the sounding of the buzzer of the primary in alarm stopped, to perform only the flashing lights, the interrupt Notify the driver visually that there is a car. (4) No alarm: In cases other than the above cases, the buzzer does not sound and the lamp does not blink, and no alarm is issued.

A specific control example of the above-described control 14 will be described with reference to the flowchart of FIG. First, an initial value is set in step S1. That is, the idle running time Td, the determination time Tx, and the decelerations α ₁ , α ₂ (α ₁ = α ₂ ) at the time of full braking of the own vehicle 12 and the front vehicle 22 are set.

While the truck 12 is running, the inter-vehicle distance D is calculated in step S2 based on the above-described formula, and in step S3, the presence or absence of an interrupted vehicle is detected from a change in the inter-vehicle distance D. When there is an interrupted vehicle, the vehicle speed Vf is taken in from the vehicle speed sensor 17 in step S4, and it is determined in step S5 whether Vf < _VH (expressway or general road). Vf ≥ _VH (highway driving)
Then, in the next step S6, the preceding vehicle speed Va is obtained from the change in the inter-vehicle distance D and the own vehicle speed Vf as described above. Next, the environment, that is, the road surface condition is detected by the environment sensor 24 and the like. (Step S7). For example, it is detected whether the wiper switch 23 is in the ON state. Next, the decelerations α ₁ and α _{2 of} the own vehicle 12 and the front vehicle 22 are changed according to the road surface condition. (Step S8). If the environment information is not detected in the previous step S7, the initially set decelerations α ₁ and α ₂ are adopted as they are.

Thus, in step S9, the own vehicle speed Vf, the preceding vehicle speed Va,
The safe inter-vehicle distances D _S1 and D _S2 are obtained from the decelerations α ₁ and α ₂ . This safety inter-vehicle distance takes into account the speed of the front vehicle 22,
In addition, it is appropriately corrected according to the road surface condition.

In step S10, the following distance D is compared with the safe inter-vehicle distances D _S1 and D _S2 , and the own vehicle speed Vf is compared with the preceding vehicle speed Va, so that D _S2 ≦ D <D _S1 and Va <Vf. It is determined whether or not. If affirmative, in step S12, the intermittent sounding of the buzzer during the primary alarm is omitted and only the lamp blinks. If negative in step S10, it is determined in step S11 whether D < _DS2 and Va <Vf, and if positive, a secondary alarm is generated by continuous buzzer sounding and lamp blinking in step S14. If not, nothing is issued (step S15).

If there is no interrupted vehicle in step S3, after the own vehicle speed Vf is acquired in step S16, or after it is determined in step S5 that Vf < _VH (general road), in step S17. The front vehicle speed Va is determined, and the same processing as in steps S7 to S10 described above is performed in steps S18 to S2.
Perform in step 1. That is, in step S21, D _S2 ≦ D <D _S1 and V
It is determined whether or not a <Vf. If affirmative, in step S13, a primary alarm is issued by buzzer sounding several times and lamp flashing. If negative in step S21, it is determined in step S22 whether D < _DS2 and Va <Vf, and if affirmative, a secondary alarm is issued in step S14. Does not issue an alarm (step S15). The above calculation is repeated while the vehicle 12 is running.

When driving on a circuit such as a circuit on a highway,
Each laser beam 16a, 16b,
If the detection area of the front vehicle 22 by 16c is set aside, the reflector of the guardrail is detected, and an alarm is frequently generated even though there is no need to issue an alarm. This rather distracts the driver's attention. Therefore, in this embodiment, the rail light 16
According to a, 16b and 16c, the area for detecting whether or not the vehicle is present ahead is changed to the area where the reflector of the guardrail is not detected. That is, as shown in FIG. 7, each of the laser beams 16a, 16a
The detection areas SL, SC, SR of b, 16c are changed. Therefore, as shown in FIG.
A disk 19 provided on the steering column as 8
And a light emitting / receiving unit 20 for detecting the slit thereof,
The steering angle signal, which is the detection signal, is input to the control unit 14. The curvature radius R of the road of the turning circuit 34 is the same as that of the steering sensor 18 described above.
Is determined by the steering angle, and based on this,
The detection area of each of the laser beams 16a, 16b, 16c is obtained from the relationship between the road curvature radius R and the detection area S (FIG. 8) which is obtained in advance.

The details of the steering sensor 18 are shown in FIGS. The disk 19 is provided with slits 31 for angle detection at regular intervals, and inside thereof,
One neutral position detecting slit 32 is provided at a position shifted from the center between the slits 31. The light emitting unit / light receiving unit 20 has two slits 31 (2
0a, 20b) and one for slit 32 detection (2
0c) provided. Since the positions of the slits 31 on both sides of the slit 32 are different from those of the slit 32, whether the clockwise or counterclockwise rotation is detected with respect to the neutral position is detected. The neutral position is detected when the slit 32 is detected at a vehicle speed of 40 km / h or more and the neutral position, that is, when the steering angle is 0 °. Then, based on this position, it is detected clockwise or counterclockwise several times based on the detection amount of the slit 31.

As described above, when the turning direction is detected using the steering sensor 18 and the detection area of each laser beam is set based on the radius of curvature of the road, the processing shown in FIG. 11 (steps S23 to S26) is performed, for example. Step S in FIG.
9 and S10, and between steps S20 and S21. That is, step S9 or S2 in FIG.
After calculating the safe inter-vehicle distances D _S1 and D _S2 at 0, the steering angle is detected by the steering sensor 18 (step S23), and then at step S24, whether the steering wheel is at the neutral position, that is, whether the vehicle is traveling straight or turning. Is determined. If the steering wheel is in the neutral position, the vehicle is going straight, so that the corresponding step S1 in FIG.
0 or S21. On the other hand, the aforementioned step S2
If it is determined in step 3 that the steering wheel is not at the neutral position, the vehicle is turning, and in step S25, the detection areas SL, SC, SR of the laser beams 16a, 16b, 16c are determined based on the turning direction and the steering angle. Is obtained from the map 33 shown in FIG. That is, as shown in FIG. 7, the detection distance is limited, and an object located beyond the detection distance is not read. This operation is performed by not performing distance detection when the time until the laser light returns is equal to or longer than a certain value.

Next, the inter-vehicle distance D and the detection areas SL, SC,
SR (step S26), and if the inter-vehicle distance D is larger than the detection areas SL, SC, SR, the process proceeds to step S15 in FIG. 6, and no alarm is generated.

If the inter-vehicle distance D is smaller than the detection areas SL, SC, SR, step S10 or S21 in FIG.
Move to the corresponding one.

[0025]

According to the inter-vehicle distance detecting / warning apparatus of the present invention, the inter-vehicle distance is reduced to the second inter-vehicle safe inter-vehicle distance when the own vehicle is running at a predetermined speed or more even when there is an interrupted vehicle.
Distance (D _S2) primary alarm for safe distance above (D _S1)
If the vehicle speed is lower than the speed of the preceding vehicle, it is determined that the vehicle is running smoothly on the road, and an alarm with only a lamp is issued.
Since the alarm is issued, an unnecessary buzzer alarm is not issued when there is an interrupted vehicle, and the rate at which the driver feels annoying is reduced . The distance between vehicles (D)
Is less than the secondary inter-vehicle safety distance (D _S2 ) and the vehicle speed
When the speed is faster than the speed of the preceding vehicle,
Raises a buzzer alarm. Therefore, an alarm only for the lamp is issued.
When the previous car suddenly brakes while
Also emits a buzzer alarm in addition to the lamp alarm,
This has the effect of preventing rear-end collision .

[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.

FIG. 7 is an explanatory diagram of a state in which a detection area during the traveling of a lane is restricted.

FIG. 8 is a diagram showing a relationship between a radius of curvature of a road and a detection area.

FIG. 9 is a perspective view of a steering sensor.

FIG. 10 is an explanatory diagram of steering angle detection.

FIG. 11 is a flowchart of a circuit measure.

[Explanation of symbols]

 Reference Signs List 1 laser radar unit 12 own vehicle 14 control unit 16a, 16b, 16c laser beam 17 vehicle speed sensor 18 steering sensor 21 display unit 23 wiper switch

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G08G 1/16 B60R 21/00 620

Claims (1)

(57) [Claims] 1. 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 returns, and an alarm is issued when the inter-vehicle distance is smaller than a safe inter-vehicle distance. In the inter-vehicle distance detection and alarm device,
Determines whether there is an interrupted vehicle and whether or not the speed of the own vehicle is higher than a predetermined speed.
The distance between vehicles (D) is the safe inter-vehicle distance for the second warning
(D _S2 ) or more and less than the primary warning safe inter-vehicle distance (D _S1 )
And only when the own vehicle speed is faster than the preceding vehicle speed
(S12) is issued, and the inter-vehicle distance (D) is the second warning safety
When the own vehicle speed is faster than the preceding vehicle speed when the inter-vehicle distance ( _DS2 ) is less than
An inter-vehicle distance detection / warning device characterized by issuing a warning of a lamp and a buzzer (S14) .