JP2830576B2 - 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, the inter-vehicle distance between the host vehicle and the preceding vehicle is currently detected, and an inter-vehicle distance detection / warning is performed so that a warning is issued to the driver when the distance becomes less than a certain distance (safe inter-vehicle distance). Alarm devices have been 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 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]

The safety inter-vehicle distance is, of course, changed according to the speed of the vehicle.
It also depends on the deceleration when the vehicle brakes. The deceleration itself changes depending on the loaded state of the vehicle. In other words, the deceleration the greater load capacity is decreases, deceleration smaller the load weight on the contrary increases, when the sudden braking or digits as will become possible to suddenly stop. Therefore, if the safe inter-vehicle distance is changed only by the speed of the vehicle, it is predicted that the warning is generated too early or late.

[0004]

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.
In an inter-vehicle distance detection / warning apparatus that issues an alarm when the inter-vehicle distance becomes smaller than the safe inter-vehicle distance obtained based on the own vehicle's braking distance or idle running distance, In addition to calculating the deceleration of the preceding vehicle as one element, a loading amount detecting means of the own vehicle and a loading state determining means of the preceding vehicle are provided, and the own vehicle and the preceding vehicle are determined based on the detection and determination results from these means. Change the deceleration of at least
Also, regarding the deceleration of the own vehicle, the
The deceleration is automatically changed according to the output signal .

[0005]

According to the inter-vehicle distance detecting / warning device having the above-mentioned structure,
Since the decelerations of the own vehicle and the preceding vehicle are considered as one factor and are changed according to the loaded state to obtain the safe inter-vehicle distance, an alarm at a more appropriate position can be obtained.

[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 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 drive circuit 4, a laser diode 5, and a light emitting lens 6, and emits laser light 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 laser radar 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.

Reference numeral 17 denotes a vehicle speed sensor which detects the 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 that functions as an example of an environment sensor, and its ON and OFF signals are 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 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 thus the road surface conditions, for example, a frozen state, in combination with the detection results of 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 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.

Further, the vehicle is provided with a load detecting device 31, and the detection result is transmitted to the control unit 14.
Is input to Then, in the control unit 14, the deceleration alpha ₁ in accordance with the load amount is read on the basis of the previously obtained map as shown in FIG. Since the deceleration changes depending on the condition of the road surface, the deceleration is determined by, for example, whether or not the wiper switch is ON, and the deceleration is replaced by A and B in FIG.

Although the deceleration α _{2 of the} front vehicle 22 also changes depending on the load weight, in this embodiment, a changeover switch 32 is provided in the driver's seat so that whether the front vehicle 22 is in the load state can be selected. I have to. This selection is not limited to light and heavy, and may be stepwise. The front car 22
When the vehicle-to-vehicle information system is constructed between the vehicle 12 and the host vehicle 12, the detection result of the loading amount detection device 31 of the front vehicle 22 is also taken in the rear vehicle 12, and is obtained in advance as shown in FIG. it may be reading the deceleration α ₂ from the map.

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 determined by calculation from 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 depress the brake pedal, ie, the idle running time Td (s), and the time for the driver to judge the danger, ie, the judgment time Tx (s), are set in advance. It is stored in the memory of the control unit 14.

The braking distance L of the front vehicle 22₁Is the above front vehicle speed
Va and deceleration α_Two(m / s^Two) And from L₁ = Va^Two/ 2α_TwoBy
Be determined. The deceleration of the front vehicle 22 is, for example,
The switching is determined according to the loading state of the front vehicle 22.

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.
L ₃ = Vf ² / 2α ₁ from the deceleration α ₁ (m / s ² ). The deceleration α ₁ of the vehicle 12 is determined based on the detection result of the load amount detection device 31 based on FIG.

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 ) = 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 optimum warning time is determined because the calculation of the safe inter-vehicle distance Ds also takes into account the deceleration of the own vehicle 12 and the front vehicle 22.

When the inter-vehicle distance becomes smaller, it is more effective to warn the driver more strongly. Therefore, when D <Ds described above, a primary alarm area (caution alarm area) is used. The warning sound is generated intermittently and the distance D
D < Td Vf + (Vf ² / 2α ₁ −Va ² / 2α ₂ ) = Ds
_{When the} vehicle reaches ₁ (safety vehicle distance), it is defined as a secondary warning area (warning warning area). In this area, a warning sound is generated continuously. This state does not require the driver's judgment,
This is a state that requires immediate application of the brake.

Next, a specific control example by the control unit 14 in the apparatus of this 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 judgment time T
x is 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 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 load amount of the own vehicle 12 is detected by the load amount detecting device 31 of the own vehicle 12, and based on the detection result and information on whether the wiper switch 23 is ON or not, a map 33 shown in FIG. more vehicle deceleration alpha ₁ is determined (step (6)).

Next, a switch 3 for determining the load amount of the preceding vehicle
2 is ON or whether it is determined (step (7)), when it is OFF, for example it is determined that the loading state determining deceleration alpha ₂ of the preceding vehicle (step (8)). Then, the vehicle deceleration previously determined alpha ₁ and the this preceding vehicle deceleration alpha ₂ as an element, safe distance Ds is calculated by the above equation (step (9)).

Next, the current inter-vehicle distance D is the safe inter-vehicle distance D.
It is determined whether it is equal to or greater than s (step (10)).
If the distance is equal to or longer than the safe inter-vehicle distance Ds, the process proceeds to step (11), and it is not necessary to generate an alarm. Therefore, no alarm is generated, and only the inter-vehicle distance is displayed on the display unit 21.

In step (10), the current inter-vehicle distance D
Is smaller than the safe inter-vehicle distance Ds, it is then determined whether or not the speed difference between the preceding vehicle 22 and the own vehicle 12 is 0 or more (step (12)). If it is 0 or more, even if it is in the area to be warned, since it is in a state of being gradually separated, the process proceeds to step (11), and no warning is issued, and only the following distance is displayed (step (11)).

If the speed difference between the preceding vehicle 22 and the own vehicle 12 is not 0 or more, since the vehicle is in the area to be warned and is gradually approaching, an alarm is generated and the distance between vehicles is displayed. I do.

In the step (7), the switch 32 is turned on.
If it is, for example, determine that it is empty
Larger deceleration α when loading_TwoDecision and deceleration of own vehicle ahead
Degree α ₁To calculate the safe inter-vehicle distance Ds
(Step (14)). Thereafter, step (10) is performed as described above.
The processing of (13) is performed.

From the above, for example, even when the braking distance is long when the vehicle 12 is loaded and the front vehicle 22 is empty and the braking distance is short, an appropriate safe inter-vehicle distance Ds is calculated and an appropriate safety inter-vehicle distance Ds is calculated. An alert will be issued at the appropriate time.

As described above, when the deceleration α ₂ of the front vehicle 22 is determined by detecting the loading amount of the front vehicle 22 from the inter-vehicle information, a map as shown in FIG. 7 is used. The process is a flowchart shown in FIG.
Is replaced by

[0034]

According to the inter-vehicle distance detecting / warning apparatus of the present invention, the safe inter-vehicle distance is obtained by changing the deceleration in accordance with the loaded state of the vehicle. The warning at is obtained.

[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 diagram showing a relationship between a vehicle loading amount and deceleration.

FIG. 7 is a diagram showing a relationship between a front vehicle loading amount and deceleration.

FIG. 8 is a flowchart of one 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 23 wiper switch 24 environment sensor 31 load detecting device 32 load 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. The inter-vehicle distance detection / warning device which issues an alarm when the distance between the vehicles becomes smaller than the safe inter-vehicle distance obtained in (1), calculates the safe inter-vehicle distance as a deceleration of the own vehicle and the preceding vehicle as one element, and the load weight detecting means and provided with a preceding vehicle of the loading state determining means, said modify the vehicle and preceding vehicle deceleration based on the detection and determination result from these means, at least
Regarding the deceleration of the vehicle, the output from the
An inter-vehicle distance detection / warning device wherein the deceleration is automatically changed according to a force signal .