JPH05225498A - Inter-vehicle distance detecting and alarming device - Google Patents

Abstract

PURPOSE:To improve the alarm function by changing the area, the period, or the like of the occurrence of alarm based on information from a preceding vehicle to prevent the occurrence of erroneous alarm and the delay of alarm. CONSTITUTION:An inter-vehicle distance signal as the detection value of a laser radar unit 1, the detection signal of a vehicle speed sensor 17, the steering angle signal of a steering sensor 18, the turning-on/off signal of a viper switch 23, the detection result of a circumstance sensor 24, etc., are inputted to a control unit 14. An inter-vehicle information control unit 42 takes in information from vehicles running near it and sends its own vehicle information and takes in the road condition and the traffic density from the preceding vehicle as information of inter-vehicle distance detection and alarm and inputs them to the control unit 14. The inter-vehicle distance, the speed of the vehicle itself, and that of the preceding vehicle are obtained by the laser radar unit 1, the vehicle speed sensor 17, and the inter-vehicle distance change per minute time respectively. An alarm is raised by a buzzer when the sum of the braking distance of the preceding vehicle and the inter-vehicle distance is shorter than the sum of the automatic control distance and the free running distance of the vehicle itself.

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 for detecting an inter-vehicle distance between an own vehicle and a front vehicle, and issuing an alarm when the distance falls below a certain distance.

[0002]

2. Description of the Related Art The causes of rear-end collisions caused by trucks are mainly
The majority of the drivers are dozing driving and aimless driving.
Under such circumstances, an inter-vehicle distance detection / warning device has now been developed that detects the inter-vehicle distance between the own vehicle and the preceding vehicle, and issues an alarm to the driver when the distance falls below a certain distance. ing. The outline of the current state of this device is that laser light is emitted forward from the own vehicle, the laser light hits the reflector on the rear surface of the front vehicle and is reflected, and from that time the inter-vehicle distance When the inter-vehicle distance becomes equal to or less than a predetermined distance, the buzzer in the vehicle interior is sounded.

By the way, as such an inter-vehicle distance detecting / warning device, since a guard rail or the like is detected in a turning circuit, it is attempted to temporarily change the detection area. Further, in rainy weather or the like, the road surface becomes slippery, and therefore, a system has been considered in which an alarm is issued early when a wiper switch signal is input.

[0004]

However, it is only after the vehicle has entered the turning circuit that the detection area can be changed by the turning circuit. Therefore, when the steering is not turned immediately before entering the turning circuit, Detects guardrails, etc. and gives a temporary alarm even if it is not dangerous.

Further, if the road surface condition is detected only by the wiper switch signal, when the wiper is not operated, such as on an icy road, an alarm is not issued early even if the road surface is actually slippery. The problem also arises.

Further, when traveling on an expressway, traffic may suddenly become congested. In such a case, the warning is delayed. Due to the performance of the laser radar, the detection limit is 100 to 120 m, and the detection will be delayed particularly when there is traffic congestion at the end of the turning circuit.

There is a technique disclosed in Japanese Patent Publication No. 60-41400 for detecting the situation in front and transmitting the information to a vehicle behind, which is mainly used for the purpose of preventing multiple collisions. The information is sent to the rear vehicle, not the road condition or the traffic jam condition.

[0008]

In order to solve the above-mentioned problems, in the present invention, the time until the laser beam emitted from the own vehicle is reflected by the preceding vehicle and returns is obtained to obtain the inter-vehicle distance,
In this inter-vehicle distance detection / alarm device, which gives an alarm when the inter-vehicle distance becomes smaller than a predetermined distance determined based on the braking distance of the vehicle and the free running distance, the road surface condition detected by the preceding vehicle, Information about the driving environment is taken in by the rear vehicle, and the area in which the alarm is generated is changed in consideration of not only the distance from the front vehicle, the road surface condition of the rear vehicle itself and the driving environment but also the above information. To do.

[0009]

According to the inter-vehicle distance detecting / warning device, the front road condition is known from the information from the front vehicle, and the alarm generation timing is changed based on the information, so that the alarm at an appropriate timing can be realized.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a device configuration of an embodiment of an inter-vehicle distance detecting / warning device according to the present invention, and FIG. 2 shows an outline of its mounting position relationship.

A laser radar unit 1 includes a light emitting portion 2 and a light receiving portion 3. The configuration of the laser radar unit 1 is shown in FIG. The light emitting unit 2 in the laser radar unit 1 is composed of a laser diode drive circuit 4, a laser diode 5, and a light emitting lens 6, and emits a laser beam in a pulse shape at regular time intervals. The light receiving unit 3 includes a light receiving lens 7 that receives the laser light reflected by the reflector of the front vehicle, a photodiode 8, an amplifier 9, a signal processor 10, and the like. These light emitting parts 2
From the time difference Δt between the light emission by the light receiving unit 3 and the light receiving by the light receiving unit 3, the distance detection circuit 11 detects the inter-vehicle distance D (= (Δt / 2) ×
Speed of light) is required.

The inter-vehicle distance signal, which is a detection value of the laser radar unit 1, is incorporated in the underside of the seat 13 of the truck 12 and is a control unit 14 as a control system.
Entered in.

The laser radar unit 1 is assembled in the bumper 15 of the 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 provided on the left, center, and right.
It emits a, 16b, and 16c. In the figure,
41 shows a road.

A vehicle speed sensor 17 detects the vehicle speed from the 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 disc 19 provided in the steering column and a light emitting / receiving portion 20 for detecting the slit thereof, and a steering angle signal which is a detection signal thereof is inputted to the control unit 14. There is.

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 slit 32 for neutral position detection is provided with the position shifted from the center between the slits 31. There are two light-emitting / light-receiving parts 20 for detecting the slit 31 (20
a, 20b), one for slit 32 detection (20
c) It is provided. Since the positional relationship between the slits 32 on both sides of the slit 32 is different, clockwise or counterclockwise rotation is detected with respect to the neutral position.

To detect the neutral position, the time when the vehicle speed is 40 km / h or more and the slit 32 is detected is determined to be the neutral position, that is, the steering angle is 0 °. Then, based on this position, the detection amount of the slit 31 is used to detect how many times clockwise or counterclockwise.

A wiper switch 23 functions as an example of an environment sensor, and ON / OFF signals thereof are input to the control unit 14. That is, when the wiper switch 23 is turned on, it is determined that it is raining.

As the other environment sensor 24, a raindrop sensor, a road surface sensor (G sensor), a temperature sensor, a slip sensor, etc. are equipped. According to the raindrop sensor, it is detected that it is raining, that is, the road surface is wet,
The road surface sensor detects whether the road surface is a turning road or other conditions, and the temperature sensor detects weather and eventually road surface conditions such as a frozen state in combination with the detection results of other sensors. The slip sensor detects whether or not the road surface is likely to slip, that is, whether the road is a low μ road or a high μ road, based on the difference in rotational speed between the front wheels and the rear wheels. The detection result is input to the control unit 14.

Reference numeral 21 is a display unit incorporated in the instrument panel in front of the driver's seat, which is provided with a display unit for the inter-vehicle distance, a buzzer for issuing an alarm, a ramp for blinking when an alarm is issued, etc. to call attention to the driver, It also warns you.

Further, the present apparatus is provided with an inter-vehicle information control unit 42. This unit 42 takes in information from a vehicle traveling in the vicinity by digital communication and also sends own vehicle information. As information for detecting and warning an inter-vehicle distance, a road condition (turning circuit, Bad road, snow wall condition, etc.), traffic volume (congestion, accident information, etc.)
Take in. Then, this information is input to the control unit 14 for the inter-vehicle distance detection / warning device.

Next, the calculation process leading to the alarm generation by the apparatus of this embodiment will be described. Own vehicle 1 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. The speed Va (m / s) of the front vehicle 22 is calculated by a 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.

On the other hand, the time required for the driver to judge that the driver is in danger and to step on the brake pedal, that is, the free running time Td (s), the time for the driver to judge that the driver is dangerous, that is, the judgment time Tx (s) and The vehicle deceleration α ₁ (m / s ² ) and the preceding vehicle deceleration α ₂ (m / s ² ) are stored in advance in the memory of the control unit 14. The decelerations α ₁ and α ₂ are stored as values assuming full braking, and normally α ₁ = α ₂ .

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

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

The braking distance L ₃ of the vehicle 12 is determined by the vehicle speed Vf.
And deceleration rate α ₁ , L ₃ = Vf ² / 2α ₁ .

Therefore, as a condition for generating an alarm, the sum of the front vehicle braking distance L ₁ and the inter-vehicle distance D is the automatic braking distance L ₃
And when it becomes smaller than the sum of the vehicle free running 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 (safe inter-vehicle distance), the buzzer incorporated in the display unit 21 issues an alarm 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 consideration when calculating s, the front vehicle 2
The optimum alarm time is determined by whether the vehicle 2 is running at high speed or low speed, whether it is accelerating or decelerating, and whether it is stopped. When the front vehicle 22 is stopped, Va = 0 in the equation.

By the way, the vehicle decelerations α ₁ and α ₂ are small on a wet road surface or a frozen road surface in the case of rain.
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 to change the alarm generation inter-vehicle distance. That is, on a wet road surface or the like, the safe inter-vehicle distance Ds automatically changes, and the alarm generation time is advanced.
For example, if the deceleration rate α ₁ (= α ₂ ) on a dry road is about 0.3 G, depending on the road surface condition, 0.2 G (for example, a wet road surface) or 0.1 G (for example, a frozen road or snow) Change the way).

Further, when traveling on the turning circuit 34 of an expressway, each laser beam 16a, 16b, 16 is driven in the same manner as when traveling straight ahead.
If the detection area of the front vehicle 22 due to c is set aside, the reflector of the guardrail will be detected, and the alarm will be complicated even though it is not necessary to issue the alarm. This, on the contrary, distracts the driver's attention.

Therefore, in the turning circuit, the laser light 16a,
The area (alarm determination area) for detecting whether or not a vehicle is present in front by 16b and 16c is changed to an area where the reflector of the guardrail is not detected. That is, as shown in FIG. 8, each laser light 16a,
The alarm determination areas Sl, Sc, Sr of 16b, 16c are changed. The road curvature radius R of the turning circuit 34 is obtained from the steering angle by the steering sensor 18 described above, and based on this, the relationship between the road curvature radius R and the warning determination area S that is obtained in advance (FIG. 9). An alarm judgment area of each laser beam 16a, 16b, 16c is required.

Next, the control in the apparatus of this embodiment
Specific control examples by the unit are shown in the flow of FIGS.
A description will be given based on the chart. First, as shown in FIG.
Initial values are set (step (1)). That is, free running
Time Td, cutting time Tx, fulcrum of own vehicle 12 and front vehicle 22
Deceleration α during rake ₁, Α₂(Α₁= Α₂) Is set
It Next, from the inter-vehicle information control unit 42
It is determined whether the vehicle-to-vehicle information has been entered (step
(2)).

When it is determined that there is no vehicle-to-vehicle information, normal processing, that is, processing based on the detection information of the own vehicle as shown in FIG. 11 is performed (step (3)). That is, first,
The inter-vehicle distance D is calculated based on the above-described formula, the own vehicle speed Vf is detected by the vehicle speed sensor 17, and the front vehicle speed Va is obtained from the change in the inter-vehicle distance D and the own vehicle speed Vf (step (4) ( 5) (6)).

Next, the environment, that is, the road surface condition is detected by the environment sensor 24 or the like (step (7)). For example, it is detected whether the wiper switch 23 is in the ON state.

Next, the decelerations α ₁ , α _{2 of} the own vehicle and the preceding vehicle are changed according to the road surface condition (step (8)). If environmental information is not detected in the previous step (7), the default decelerations α ₁ and α ₂ are used as they are.

Next, the safe inter-vehicle distance Ds is obtained from the vehicle speed Vf, the front vehicle speed Va, the decelerations α ₁ and α ₂ detected or calculated as described above (step (9)). This safe inter-vehicle distance Ds is a value that is appropriately corrected in consideration of the speed of the front vehicle 22 and according to road surface conditions.

Next, the steering angle is detected by the steering sensor 18 (step (10)), and it is determined from the steering angle whether the vehicle is going straight, turning right, or turning left. The alarm determination areas (areas to be detected) Sl, Sc, Sr of the laser beams 16a, 16b, 16c are determined from the map 33 as shown in FIG. 9 (step (11)). That is, as shown in FIG. 8, the distance is limited, and an object ahead of that is not read. This operation is handled by not performing distance detection when the time until the laser light returns is longer than a certain time.

Next, the previously determined safe inter-vehicle distance Ds is compared with the actually measured inter-vehicle distance D (step (1
2)). However, the inter-vehicle distance D and the warning judgment areas Sl, Sc,
Compared with Sr, the inter-vehicle distance D shows that the warning judgment areas Sl, S
When it is larger than c and Sr, it is judged that the guardrail or the like is detected, so that the process shifts to step (13) and no alarm is issued and only the inter-vehicle distance is displayed on the display unit 21. The inter-vehicle distance D is the warning judgment area Sl, Sc, S
When it is smaller than r, the inter-vehicle distance D is the safe inter-vehicle distance Ds.
It is determined whether it is greater than. Note that step (12)
At the inter-vehicle distance D, all the warning judgment areas Sl, S
The reason why c and Sr are compared is to detect an interrupting vehicle or the like. If the inter-vehicle distance D is smaller than the safe inter-vehicle distance Ds, the process proceeds to step (13) and no alarm is issued.

When it is determined that the inter-vehicle distance D is greater than the safe inter-vehicle distance Ds, next, the front vehicle speed Va and the own vehicle speed V
Compare with f (step (14)). When the front vehicle speed Va is large, the inter-vehicle distance D is increasing, and therefore it is not necessary to issue an alarm, and the process proceeds to step (13) to display only the inter-vehicle distance D.

When the front vehicle speed Va is smaller than the own vehicle speed Vf, it is in an area to be warned and is gradually approaching. Therefore, an alarm issuing command is issued to the display unit 21 and an alarm is issued. In addition, the inter-vehicle distance D is also displayed (step (15)).

When it is judged in the step (2) that there is vehicle-to-vehicle information, it is then judged whether or not there is a curve road and a snow wall condition signal (step (16)). If it is determined to be "present", control is performed to change the alarm determination area based on the information from the preceding vehicle (step (17)). That is, as shown in the subroutine of FIG. 12, the warning determination area S is not based on the detection result of the steering angle but based on the information from the preceding vehicle.
l, Sc, Sr are determined (step (22) (2
3)). The calculation and processing before and after are performed in the same manner as that shown in FIG.

If it is determined in step 16 that there is "no", that is, there is no information about the curved road or the like, the alarm generation distance is changed based on the information from the preceding vehicle (step (28)).
That is, as shown in FIG. 13, after the inter-vehicle distance D is calculated, the own vehicle speed Vf is detected, and the preceding vehicle speed Va is calculated (steps (29) to (31)), the road surface condition from the preceding vehicle and the congestion The situation or the like is detected (step (32)), and the decelerations α ₁ , α _{2 of} the own vehicle and the preceding vehicle are determined based on the detection result (step (33)).

Next, the safe inter-vehicle distance Ds is obtained based on the decelerations α ₁ and α ₂ and the detection of the own vehicle speed Vf and the preceding vehicle speed Va (step (34)), and the actually measured inter-vehicle distance is calculated. A comparison with the distance D is made (step (35)), and just like the other processing described above, only the inter-vehicle distance is displayed if it is safe (step (36)), and if the alarm should be issued, an alarm is issued. And the inter-vehicle distance is displayed (steps (37) (3
8)). In step (35), the circuit information is also taken in and the alarm judgment area is changed, as in other processing.

FIG. 14 shows another control example. First, initial values are set, then the inter-vehicle distance D, the vehicle speed Vf detection, and the front vehicle speed Va are calculated (steps (1) to (4)).
).

Next, it is judged whether or not the vehicle-to-vehicle information is received (step (5)). If it is judged that the vehicle-to-vehicle information is not received, it is judged whether or not the wiper switch 23 is ON, and it is OFF. In some cases, fine weather deceleration α ₁ , α
_{When 2} is determined and ON, deceleration α in rainy weather
₁ and α ₂ are determined (steps (5) to (8)).

Next, it is judged again whether or not the inter-vehicle information is received (step (9)). If not received, it is determined whether or not the steering sensor 18 detects the angle. If the angle is detected, that is, if the turning circuit is running, the laser beam 16a, 16b, 16c alarm determination areas Sl, Sc, S
When r is determined and the angle is not detected, it is fixed to Sl, Sc, and Sr in the straight traveling state (steps (10) to (1
2)).

Next, the previously determined safe inter-vehicle distance Ds and the actually measured inter-vehicle distance D are compared (step (1
3)). However, the inter-vehicle distance D and the warning judgment areas Sl, Sc,
Compared with Sr, the inter-vehicle distance D shows that the warning judgment areas Sl, S
If it is larger than c and Sr, it is judged that a guardrail or the like has been detected, so the routine proceeds to step (14), where no alarm is issued and only the inter-vehicle distance is displayed on the display unit 21. The inter-vehicle distance D is the warning judgment area Sl, Sc, Sr.
If it is smaller, it is determined whether the inter-vehicle distance D is greater than the safe inter-vehicle distance Ds. In step (13), the inter-vehicle distance D and all the warning judgment areas Sl, S
The reason why c and Sr are compared is to detect an interrupting vehicle or the like. When the inter-vehicle distance D is smaller than the safe inter-vehicle distance Ds, the process proceeds to step (14) and the alarm is not issued.

When it is determined that the inter-vehicle distance D is greater than the safe inter-vehicle distance Ds, next, the front vehicle speed Va and the own vehicle speed V
Compare with f (step (15)). When the front vehicle speed Va is large, the inter-vehicle distance D is in a state of increasing, and it is not necessary to issue an alarm, and the process proceeds to step (14) to display only the inter-vehicle distance D.

When the front vehicle speed Va is smaller than the own vehicle speed Vf, it is in an area to be warned and is gradually approaching. Therefore, an alarm generation command is issued to the display unit 21 and an alarm is issued. In addition, the inter-vehicle distance D is also displayed (step (16)).

If it is judged in the step (5) that the inter-vehicle information is received, then it is judged whether or not the road surface / congestion information is received. The process shifts to (step (17)). If it is received, it is next determined whether or not the wiper switch 23 is ON (step (18)). If it is ON, it means that it is raining, so the process proceeds to step (8), and the deceleration in rainy weather is performed. α
Determine ₁ and α ₂ . When the wiper switch 23 is OFF, the content of the inter-vehicle information is detected (step (19)),
Deceleration α according to the road condition and traffic congestion detected by the preceding vehicle
Determine ₁ and α ₂ . (Step (20)).

After that, the process shifts to step (9), it is judged again whether or not the vehicle-to-vehicle information is received, and if it is not received, the processing from step (10) onward considering the turning circuit is performed. If the vehicle-to-vehicle information is detected, it is determined whether or not the circuit information is received (step (21)), and if not received, the processing from step (10) is performed.

When the turning circuit information is received, it is determined whether or not the steering sensor 18 is detecting the angle. If the steering sensor 18 is detecting the angle, the own vehicle is also traveling on the turning circuit. The alarm determination areas Sl, Sc, Sr are determined based on the actual detected angle signal (step (22) (1
1)). When the steering sensor 18 does not detect the angle, only the front vehicle is in the turning circuit. Therefore, the laser beams 16a, 16b, 16 are generated based on the information of the front vehicle.
The alarm determination areas Sl, Sc, Sr based on c are determined (steps (23) and (11)). Since the alarm judgment area is changed according to the turning circuit before approaching the turning circuit, it is possible to avoid a situation in which a false alarm is generated by detecting a guardrail or the like immediately before the turning circuit. After that, the processes of steps (13) to (16) described above are performed.

It should be noted that although the alarm may or may not be issued by comparing the safe inter-vehicle distance Ds and the inter-vehicle distance D as described above, it is also possible to issue this alarm in stages. .. For example, when D <Ds, the buzzer sounds a few times as the primary alarm (caution alarm), and the secondary alarm is D <Td Vf + (Vf ² / 2α ₁ −Va ² / 2α ₂ ) = Ds ₁
When the "warning distance" is reached, in this case, the buzzer sounds continuously. In this state, the driver's judgment is not required, and the brake must be immediately applied. If the warning is gradual, the driver can respond quickly. Further, the present invention is not limited to trucks, but can be similarly applied to buses, passenger cars, and the like.

[0053]

According to the inter-vehicle distance detecting / warning device of the present invention, the warning area, timing, etc. are changed based on the information from the vehicle in front, so that the guard rail etc. can be detected even before entering the turning circuit. It is possible to prevent the occurrence of false alarms due to the fact that the alarms have occurred, and since the road surface, the environmental condition, and the like are known in advance to deal with them, there is no delay in the alarm, and the alarm function is improved.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of a schematic positional relationship of each component.

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

FIG. 4 is a plan view of a laser beam starting state.

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 showing a state in which a detection area by laser light is changed between an expressway and a general road.

FIG. 9 is a diagram showing a relationship between a road curve radius and an alarm judgment area.

FIG. 10 is a flowchart of an example.

11 is a subroutine in FIG.

12 is a subroutine in FIG.

13 is a subroutine in FIG.

FIG. 14 is a flowchart of another control example.

[Explanation of symbols]

 1 laser radar unit 12 own vehicle 14 control unit 16a, 16b, 16c laser light 17 vehicle speed sensor 18 steering sensor 21 display unit 22 front vehicle 23 steering sensor 24 environment sensor 42 vehicle-to-vehicle information control unit

Claims (1)

[Claims] 1. A vehicle-to-vehicle distance is obtained by detecting a time until a laser beam emitted from the vehicle is reflected by a vehicle in front and returning, and the vehicle-to-vehicle distance is calculated based on a braking distance and a free running distance of the vehicle. In the inter-vehicle distance detection / alarm device that issues an alarm when the distance becomes smaller than the predetermined distance specified in, the rear vehicle incorporates information about the road surface condition detected by the front vehicle and the traveling environment,
An inter-vehicle distance detecting / warning device, characterized in that a region for issuing the alarm is changed in consideration of not only the distance from the front vehicle, the road surface condition of the rear vehicle itself and the traveling environment but also the above information.