JP2591416Y2 - Inter-vehicle distance detection and alarm device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND 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 becomes smaller than the safe inter-vehicle distance. The present invention relates to an apparatus for dealing with glass breakage of a laser radar unit that transmits and receives light.

[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]

By the way, in the above-mentioned conventional apparatus, a laser radar unit having a laser light emitting portion and a light receiving portion is mounted, so that the life of the laser diode is prolonged, and the laser light emitting window and the laser light emitting window are provided. The inside of the laser radar unit is kept at a high vacuum to prevent water droplets from adhering to the entrance window.

However, since the laser radar unit is mounted on a front bumper or the like of the own vehicle, the front glass of the laser radar unit may be damaged by, for example, flying stones. The detection function becomes insufficient, and a case where a false display or a false alarm is output may occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inter-vehicle distance detecting / warning apparatus which prevents erroneous display and erroneous alarm due to glass breakage of a laser radar unit.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention detects the time required for the laser beam emitted from the laser radar unit of the own vehicle to return after being reflected by the preceding vehicle and to reduce the inter-vehicle distance. determined, the headway distance detection and warning apparatus that the inter-vehicle distance emits an alarm if the braking distance and empty run distance of the vehicle becomes smaller than the safe inter-vehicle distance determined on the basis of the front of the laser radar unit Equipped with glass,
When the glass breaks, the internal pressure of the laser radar unit
And a means for performing a warning while stopping the emission of laser light by the operation of the pressure sensor .

[0007]

[Function] Even if the glass of the laser radar unit is broken, there is no emission of laser light, and a warning such as a lamp display is performed to notify the driver of the broken glass. Can be prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of an inter-vehicle distance detecting / warning apparatus according to the present invention, and FIG. 1 is a laser radar unit,
It includes 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 comprises 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. 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, the distance detection circuit 11 calculates
(= Δt / 2 × light speed) is obtained.

[0010] A pressure sensor 30 is provided in the laser radar unit 1. This pressure sensor 30 is a laser radar unit 1 in a high vacuum state, particularly a laser radar unit in a high vacuum state in order to prolong the life of a laser diode and prevent water droplets on glass at a laser beam emitting / receiving section. 1 for detecting the degree of vacuum inside.
Therefore, the pressure sensor 30 operates to detect pressure when the vacuum cannot be maintained due to breakage of the glass or when the degree of vacuum gradually decreases. In this embodiment, although the pressure sensor 30 is used for detecting a sudden pressure change such as breakage of the glass, water droplets easily adhere to the inner surface of the glass even when the degree of vacuum gradually decreases.
Its detection is also possible. The pressure sensor 30 is connected to a control unit 14 described later.

The inter-vehicle distance signal and the detection signal of the pressure sensor 30 which are the detection values of the laser radar unit 1 are input to a control unit 14 incorporated below the seat 13 of the truck 12 shown in FIG. 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.

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.

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

The other environmental 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 an instrument panel in front of a driver's seat, which is provided with a display unit for an inter-vehicle distance, a warning lamp 31 for breaking a front glass of a lamp which blinks when a buzzer alarm is generated, and the like. Alerts and warns others. Note that the warning lamp having three front faces and being damaged is not limited to lamp lighting, and may be other means such as a buzzer.

Next, a description will be given of a calculation process leading to the generation of an alarm by the apparatus of the embodiment. In FIG.
The distance between the vehicle 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. 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. That is, the front vehicle speed Va is larger than the relative speed between the host vehicle 12 and the front vehicle 22.
Is required.

On the other hand, the time from when the driver determines that it is dangerous to depress the brake pedal, 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 equal to the front vehicle speed Va.
L ₁ = Va ² / 2α _2, and deceleration α 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 vehicle 12 is
From the own vehicle speed Vf and the deceleration α ₁ , L ₃ = Vf ² / 2α ₁
Is determined by Therefore, the conditions for alarm generation are:
Preceding vehicle braking distance L ₁ and the inter-vehicle distance D Distance sum host vehicle braking and L
₃ and triggered by the time 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 Accordingly, D <(Td + Tx) V
When f + (Vf ² / 2α ₁ −Va ² / 2α ₂ ) = Ds (safety inter-vehicle distance), the display unit 21
A more alarm is generated and the lamp flashes.

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.

By the way, the decelerations α ₁ and α ₂ of the vehicle are small on a wet road surface or a frozen road surface in rainy weather.
Therefore, when it is detected that the wiper switch 23 is turned on, the control unit 14 changes the numerical values of the decelerations α ₁ and α ₂ and changes the inter-vehicle distance at which the alarm is generated. 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, if the deceleration α ₁ (= α ₂ ) on a dry road is about 0.3 G, 0.2 G (for example, a wet road), 0.1 G (for example, a frozen road, Road)
And change it.

Next, specific control by the control unit 14 in the apparatus of 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.

Next, in step (2), it is determined whether the front glass of the laser radar unit 1 is damaged. That is, it is to confirm whether the laser beam can be used normally or not, and the detection value of the pressure sensor 30 is inputted to the control unit 14 to make a determination. When the damage of the front glass is detected based on the detection value of the pressure sensor 30, the process proceeds to step (3) and the output of the laser beam is stopped, and the front glass damage warning lamp 31 is turned on.

While the truck 12 is running, the inter-vehicle distance D is calculated in step (4) on the basis of the above formula, and in step (5), the own vehicle speed Vf is detected by the vehicle speed sensor 17, and the process proceeds to step (6). 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 (7)). 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 (8)).
If the environment information is not detected in the previous step (7), the default decelerations α ₁ and α ₂ are employed as they are. Next, in step (9), the safe inter-vehicle distance Ds is obtained from the own vehicle speed Vf, the preceding vehicle speed Va, the decelerations α ₁ , α _2, etc. detected or calculated as described above. This safe inter-vehicle distance Ds
Is appropriately corrected in consideration of the speed of the front vehicle 22 and according to the road surface condition.

In step (10), it is determined whether or not the inter-vehicle distance D is greater than the safe inter-vehicle distance Ds. If it is determined in step (10) that the inter-vehicle distance D is smaller than the safe inter-vehicle distance Ds, then in step (11), the front vehicle speed Va is compared with the host vehicle speed Vf. If 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). If the preceding vehicle speed Va is lower than the own vehicle speed Vf, the vehicle is in the area to be warned and is gradually approaching. Therefore, the flow proceeds to step (13), and a warning generation command is issued to the display unit 21. An alarm is issued, and the inter-vehicle distance D is also displayed.

[0026]

As described above, according to the present invention, since the front glass breakage is detected by detecting the pressure inside the laser radar unit, the beam emission is automatically stopped to cause useless oscillation. Stop and warning can inform the driver of the glass breakage.

[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 of 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 one embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser radar unit 2 Light emitting part 3 Light receiving part 30 Pressure sensor 31 Front glass breakage warning lamp

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01C 3/00-3/32 B60Q 9/00 B60R 21/00 620 G01B 11/00-11/30 G08G 1/16

Claims (1)

(57) [Scope of request for utility model registration] An inter-vehicle distance is determined by detecting a time required for a laser beam emitted from a laser radar unit of the own vehicle to be reflected and returned by a preceding vehicle, and the inter-vehicle distance is determined by the braking distance of the own vehicle.
In headway distance detection and alarm device adapted to emit a warning if it becomes smaller than the safe inter-vehicle distance determined empty run distance based, comprises a glass front face of the laser radar unit, the laser during this glass breakage Radar unit internal pressure
A pressure sensor actuated by the change, headway distance detection and alarm system is characterized in that a means for warning with light emission stop of the laser light by the operation of the pressure sensor.