JP2959255B2 - 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 predetermined distance.

[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 from 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]

The above-mentioned laser beam detects a vehicle or other obstacle ahead, but detects a guardrail at the road end or a reflector of the guardrail at the time of traveling on a circuit. That is, an alarm is generated even though the situation is not such that an alarm is generated.

[0004] For such a problem, it is conceivable that an alarm is not issued at the time of cornering, but this makes it impossible to detect a forward vehicle or the like.

[0005]

In order to solve the above-mentioned problems, according to the present invention, a time until a laser beam emitted from the own vehicle is reflected by a preceding vehicle and returns is determined to obtain an inter-vehicle distance.
An inter-vehicle distance detection / warning device which issues an alarm when the inter-vehicle distance becomes smaller than a predetermined distance determined based on a braking distance and an idling distance of the own vehicle. while a plurality arranged in a vehicle width direction emitting portion that emits a steering sensor for detecting a steering angle is provided, at the time of running of the turning road from the detection result of the steering sensor Ru emitted from the light emitting portion lasers
At least the detection area in the length direction by the light is changed in accordance with the steering angle, and when the steering sensor fails, the detection area by the laser light is made to be the same as that on a straight road.

[0006]

According to the above inter-vehicle distance detection / warning apparatus, the detection area of the front vehicle or the like is changed to an area in which the reflector of the guardrail is not detected when the vehicle is traveling on the circuit. Therefore, the driver is not bothered by the false alarm.

When the steering sensor is out of order, for example, when a signal is broken, it is detected, and the detection area by the laser beam is provisionally set to be the same as the state of traveling on a straight road.
When traveling on a curved road, a guardrail or the like may be erroneously detected, but since the function is not completely stopped, safety is ensured. Note that the change of the detection area by the laser light includes changing the detection area of the laser light length and changing the length and width of the laser light itself.

[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 emitting section 2 of the laser radar unit 1 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. These light emitting units 2
The inter-vehicle distance D (= (Δt / 2) ×
Light speed) is required.

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

The radar laser unit 1 is assembled in a bumper 15 of a truck 12 as shown in FIG.
In the present embodiment , as shown in FIG. 4, the light emitting unit 2 emits three laser beams 16a, 16b, and 16c to the left, the center, and the right. In the figure, 41 indicates a road.

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 steering sensor having a disk 19 provided on a steering column and a light emitting / receiving section 20 for detecting a slit of the disk. A steering angle signal as a detection signal is input to the control unit 14. I have.

Details of the steering sensor 18 are shown in FIGS. With the disk 19 a slit 31 for angle detection is provided at regular intervals, the inside, the slits 32 for a neutral position detection is eclipsed set. The light emitting unit / light receiving unit 20 is provided with two (20a, 20b) for detecting the slit 31 and one (20c) for detecting the slit 32. And the light emitting section
The phase difference between the waveforms obtained by the light receiving units 20a and 20b
It is detected whether clockwise or counterclockwise.

As for the detection of the neutral position, the vehicle speed is
The time when the slit 32 is detected at 30 km / h or more is determined as the neutral position, that is, the time 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.

When the vehicle is running on a circuit such as a circuit on a highway, FIG.
Each of the laser beams 16a, 16b, 16
If the detection area of the front vehicle by c is set aside, the reflector of the guardrail is detected, and an alarm is generated even though it is not necessary to issue an alarm.

Therefore, in the circuit, the laser light 16a,
The area for detecting whether or not the vehicle is present ahead (warning determination area) is changed to an area in which the reflector of the guardrail is not detected by 16b and 16c. That is, as shown in FIG. 8, the warning determination areas Sl, Sc, S of the laser beams 16a, 16b, 16c are determined according to the road curvature radius R obtained based on the steering angle detected by the steering sensor 18.
Change r. The laser beams 16a, 16a
The warning judgment areas b and 16c are obtained from the relationship between the road curvature radius R and the judgment area S (FIG. 9) which is obtained in advance.

As described above, the steering angle signal is input to the control unit 14 from the steering sensor 18. When the steering sensor 18 fails, for example, when the signal line is broken, the control unit 14 needs the necessary steering angle signal. Information does not enter the control unit 14 and the control system fails. In this case, it becomes meaningless to mount the inter-vehicle distance detection / warning device. Therefore, when the steering angle is not input, the laser radar unit 1 is controlled by the control unit 14.
Then, a command is issued to detect an object ahead in the same detection area as in the straight traveling state.

Reference numeral 23 denotes a wiper switch which functions as an example of an environment sensor, and its ON / OFF signal is input to the control unit 14. That is, when the wiper switch 23 is turned on, it is determined that it is raining.

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 bumpy road, or other conditions, and the temperature sensor detects the weather and the road surface conditions, for example, a frozen state, in combination with the detection results of the other sensors. 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 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. As shown in FIG.
The distance between the vehicle 2 and the front vehicle 22, that is, the inter-vehicle distance D (m) is obtained by the laser radar unit 1 as described above.
The vehicle speed Vf (m / s) is detected by the vehicle speed sensor 17. Velocity V a of the preceding vehicle 22 (m / s) is more determined in operation than the change in the inter-vehicle distance D per short time. In other words, own car 1
The front vehicle speed Va is obtained from the relative speed between the front vehicle 2 and the front vehicle 22.

On the other hand, the time required for the driver to judge the danger and step on the brake pedal, that is, the idle running time Td (s), the time for the driver to judge the danger, that is, the judgment time Tx (s) and the self-time. The deceleration α ₁ (m / s ² ) of the vehicle and the deceleration α ₂ (m / s ² ) of the preceding vehicle are stored in the memory of the control unit 14 in advance. 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) 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 the 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 ) = Ds (safety vehicle distance) , An alarm is issued from the display unit 21 and the lamp blinks.

As can be seen from this equation, the safe inter-vehicle distance D
Since the speed of the front vehicle 22 is taken into account in the calculation of s, the front vehicle 2
The optimum warning time is determined depending on whether the vehicle 2 is traveling at high speed or low speed, whether the vehicle is accelerating or decelerating, and whether the vehicle is stopped. When the front vehicle 22 is stopped, Va = 0 in the equation.

On a wet road surface or a frozen road surface in rainy weather, the decelerations α ₁ and α ₂ of the vehicle become small. Then, when it is detected that the wiper switch 23 is turned on, the control unit 14 sets the deceleration α ₁ , α ₂
And change the distance between two vehicles that generate an alarm. That is, on a wet road surface or the like, the safe inter-vehicle distance Ds automatically changes, and the warning issuance time is advanced. For example,
Assuming that the deceleration α ₁ (= α ₂ ) on a dry road is about 0.3 G, 0.2 G (for example, a wet road surface, etc.)
It is changed to 0.1G (for example, a frozen road, a snowy road, etc.).

Next, a specific control example by the control unit 14 in this embodiment device will be described with reference to a flowchart of FIG. 10 and 11. First, an initial value is set (step (1)). 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 (2) based on the above formula, and in step (3), the vehicle speed sensor 17 detects the own vehicle speed Vf. In), 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 (5)). 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 and the preceding vehicle are changed according to the road surface condition (step (6)). If the environment information is not detected in the previous step (5), the default decelerations α ₁ and α ₂ are adopted as they are.

Next, in step (7), the vehicle speed Vf detected or calculated as described above, the preceding vehicle speed Va, the deceleration alpha _1, safe distance Ds from the alpha ₂ or the like is required. This safe inter-vehicle distance Ds is appropriately corrected in consideration of the speed of the preceding vehicle 22 and according to the road surface condition.

Next, it is determined whether or not the signal line of the steering sensor 18 is disconnected (step (8)). If there is no disconnection, the steering angle is detected by the steering sensor 18 (step (9)), and it is determined whether the vehicle is in a straight running state, a right turn, or a left turn based on the steering angle. In some cases, each laser beam 16 can be obtained from a map as shown in FIG.
a, 16b, 16c alarm judgment areas (areas to be detected)
Sl, Sc, and Sr are determined (step (1)
0))). That is, as shown in FIG. 8, the distance is limited,
Objects ahead are not read. This operation is performed by not performing distance detection when the time until the laser beam returns is longer than a certain time.

Next, the previously obtained safe inter-vehicle distance Ds is compared with the actually measured inter-vehicle distance D (step (1)
1 )) . However, the inter-vehicle distance D and the warning determination areas Sl, S
c, Sr are compared (step (9 )) . If the following distance D is larger than the warning determination areas Sl, Sc, Sr, the process proceeds to step (12 ) , and no alarm is generated, and only the following distance is displayed. 21 is displayed. Inter-vehicle distance D
Is smaller than the alarm determination areas Sl, Sc, Sr,
It is determined whether the following distance D is greater than the safe following distance Ds. In step (9 ) , the inter-vehicle distance D
Is compared with all the warning determination areas Sl, Sc, Sr in order to detect an interrupted vehicle and the like. If the inter-vehicle distance D is greater than the safe distance Ds, the step (1
Go to 2 ) and do not generate an alarm.

[0036] When the inter-vehicle distance D is determined to be smaller <br/> than the safe inter-vehicle distance Ds, then, the preceding vehicle speed Va and the vehicle speed V
Compare with f. When the preceding vehicle speed Va is large, the inter-vehicle distance D is increasing, so there is no need to issue an alarm, and the process proceeds to step (12 ), where only the inter-vehicle distance D is displayed.

If the preceding vehicle speed Va is lower than the own vehicle speed Vf, the warning is issued to the display unit 21 because the vehicle is in the area to be warned and is gradually approaching. In addition, the inter-vehicle distance D is also displayed (step (14)).

When the disconnection of the signal line of the steering sensor 18 is detected in the step (8), the laser beam 1
6a, 16b, 16c, the alarm determination areas Sl, Sc,
Sr is fixed to the value when the steering angle is 0 ° (step (15 )). In this case, in such turning road, but it may sometimes be detected and guardrails, when no emitted at all alarms due to failure of the steering sensor 18 is avoided. Note that the failure of the steering sensor 18 and the like are displayed on the display unit 21.

In the above example, the laser beam 16 having a fixed length and a fixed width is used.
Among the control methods a, 16b and 16c applied to a control method for changing the signal pickup area according to the running state, the control method for changing the length and width of the laser beams 16a, 16b and 16c according to the running state. In this case, as shown in FIG. 12, when a failure of the steering sensor 18 is detected, the lengths and widths of the laser beams 16a, 16b, and 16c are fixed to those for straight running. I do. The operation and effect are the same as in the previous example.

It should be noted that, in the present apparatus, when an alarm is generated, it may be performed stepwise. For example D <primary alarm when the Ds as (note alarm), and the buzzer is sounded several times, a secondary alarm, D <Td V f + ( 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.

[0041]

According to the inter-vehicle distance detection / warning apparatus of the present invention, even if the steering sensor fails, the detection area is fixed to the same state as when traveling on a straight road, so that the function is completely stopped. It is possible to continuously detect the preceding vehicle and generate an alarm.

[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 a perspective view of a steering sensor.

FIG. 6 is an explanatory diagram of steering angle detection.

FIG. 7 is an explanatory diagram of an inter-vehicle distance, a braking distance, and the like.

FIG. 8 is an explanatory diagram of a state in which a warning judgment area during traveling on a lane is restricted.

FIG. 9 is a diagram illustrating a relationship between a road curve radius and a warning determination area.

FIG. 10 is a flowchart of one embodiment.

FIG. 11 is a flowchart of one embodiment.

FIG. 12 is a flowchart of another embodiment.

[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 22 front vehicle 24 environment sensor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01S 7/00-7/66 G01S 13/00-17/95 B60R 21/00 G08G 1/16

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 detection / warning device that issues an alarm when the distance becomes smaller than a predetermined distance defined in (2), a plurality of light emitting units that emit the laser light toward the front of the vehicle are arranged in a vehicle width direction, the steering sensor for detecting a steering angle is provided, the laser light for the running of the turning road from the detection result of the steering sensor that will be emitted from the light emitting portion
At least the detection area in the length direction is changed according to the steering angle, and when the steering sensor fails, the detection area by the laser beam is made to be the same as that on a straight road.・ Alarm device.