JPH04215088A - Intercar distance display and alarm device - Google Patents

Abstract

PURPOSE:To take a driver's attention to an intercar distance with enough time by providing an intercar distance variable indicator and an alarm distance variable indicator. CONSTITUTION:A pointer 213 indicates a minimum of a safe intercar distance between a preceding car and a diver's car at a current car speed and a pointer 214 indicates an intercar distance being risky in environment and at a car speed at a current state. Thus, when an intercar distance exceeding the value of the pointer 213 is kept, a car is in an enough safe running state, and when it approaches the pointer 213, a state where it is about to be outside a safe intercar distance is produced. A portion between the pointers 213 and 214 indicates a first alarm distance between cars, and an intercar distance shorter than the value of the pointer 214 is a risk intercar distance (a second alarm distance between cars). Though the pointers 213 and 214 are changed at any time according to a change in environment and a car speed, the current intercar distance state is always and easily confirmed only by discriminating that intercar distance display is made on the right side of the pointer 213 or it is made between the pointers 213 and 214 or it is made on the left side of the pointer 214.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to an inter-vehicle distance display/warning device that detects and displays the inter-vehicle distance between one's own vehicle and the vehicle in front, and issues an alarm when the distance becomes smaller than a safe inter-vehicle distance. .

0002

[Prior Art] The main causes of rear-end collisions caused by trucks are:
The majority of cases are caused by drivers falling asleep at the wheel or driving distracted. Due to these circumstances, a following distance detection/warning device has been developed that detects the distance between the own vehicle and the vehicle in front and issues a warning to the driver when the distance becomes less than a certain distance. ing. The current outline of this device is that it emits a laser beam in front of the vehicle, receives the laser beam that hits the reflector on the rear of the vehicle in front, receives the reflected light, and calculates the distance between vehicles based on the time. When the inter-vehicle distance falls below a predetermined distance, a buzzer inside the vehicle will sound.

0003

By the way, in the above-mentioned conventional device, when displaying the detected inter-vehicle distance, it is also possible to include a display device that variably displays the inter-vehicle distance using a meter.

However, like a speedometer, this display only displays the distance between vehicles, and if you get too close to the vehicle in front and the distance is not safe, a buzzer will suddenly sound. In other words, it does not display the level of safety, such as whether or not the current distance between vehicles is safe, or how safe it is, and it does not indicate the level of safety, such as whether or not the current distance is a safe distance, and it is not a display that prompts the driver to pay attention to the distance between vehicles in advance. Not yet. Buzzers exist to call the driver's attention, but this buzzer is designed to alert the driver that there is a sudden danger when driving.
On the other hand, the driver becomes panicked and it takes time to apply the brakes.
It is not possible to warn the driver in a timely manner, such as that it is dangerous to drive in this state.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, it is an object of the present invention to provide an inter-vehicle distance display/warning device that alerts the driver of the inter-vehicle distance with sufficient time.

[0006]

[Means for Solving the Problems] The present invention achieves the above-mentioned object by detecting the time it takes for a laser beam emitted from the own vehicle to be reflected by the vehicle in front and returning, to determine and display the inter-vehicle distance. ,
In a following distance display/warning device that issues a warning when this following distance becomes smaller than a safe following distance determined based on the own vehicle's braking distance and free running distance, the display device includes a The vehicle is characterized by having a variable distance indicator indicating the distance between the vehicles in front of the vehicle and a variable warning distance indicator between the vehicle and the vehicle in front.

[0007]

[Operation] By displaying a variable warning distance based on the current driving conditions and environment as well as a variable display of the following distance,
When the inter-vehicle distance display becomes significantly longer than the warning distance, a safe distance is determined, and within the warning distance display, the more severe the danger becomes, the more severe the warning can be issued only when the danger reaches a certain level.

[0008]

Embodiments Here, embodiments of the present invention will be described with reference to FIGS. 1 to 9. FIG. 1 shows an embodiment of the following distance display/warning device according to the present invention, and FIG.
I will explain from.

Reference numeral 1 denotes a laser radar unit, which includes a light emitting section 2 and a light receiving section 3. The configuration of the laser radar unit 1 is shown in FIG. The light receiving section 2 includes a laser diode drive circuit 4, a laser diode 5, and a light emitting lens 6, and is configured to emit pulsed laser light at regular intervals. The light receiving section 3 includes a light receiving lens 7 that receives laser light reflected by a reflector of the front vehicle, a photodiode 8, an amplifier 9, a signal processor 10, and the like. Based on the time difference Δt between the light emitted by the light emitting section 2 and the light received by the light receiving section 3, the distance detection circuit 11 determines the inter-vehicle distance D.
(=(Δt/2)×speed of light) is obtained.

An inter-vehicle distance signal, which is a detected value of the laser radar unit 1, is input to a control unit 14 built into the lower side of the seat 13 of the truck 12 shown in FIG.

The laser radar unit 1 is assembled into 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 Figure 5, three laser beams 16 are placed on the left, center, and right.
a, 16b, and 16c.

Reference numeral 17 shown in FIG. 2 is a vehicle speed sensor, which detects the vehicle speed from a rotating part of the transmission or the like. A detection signal from the vehicle speed sensor 17 is input to the control unit 14. Reference numeral 18 denotes a steering sensor comprising a disk 18a provided on the steering column and a light emitting/light receiving section 18b for detecting the slit thereof, and a steering angle signal as a detection signal thereof is inputted to the control unit 14. There is.

A wiper switch 19 functions as an example of an environmental sensor, and its ON/OFF signals are input to the control unit 14. In other words, it is determined that it is raining when the wiper switch 19 is turned on.

Other environmental sensors 20 include a raindrop sensor, a road surface sensor (G sensor), a temperature sensor, a slip sensor, and the like. A rain sensor detects that it is raining, i.e. the road is wet, a road sensor detects whether the road is muddy or otherwise, and a temperature sensor detects whether the road is muddy or wet. In combination with detection results from other sensors, the weather and road conditions, such as icy conditions, are detected. The slip sensor detects whether the road surface is prone to slipping, that is, whether the road is a low-μ road or a high-μ road, based on the rotational speed difference between the front wheels and the rear wheels. The detection results are input to the control unit 14.

Reference numeral 21 is a display unit built into the instrument panel in front of the driver's seat, and is equipped with a display unit for the distance between vehicles, a buzzer that issues an alarm, and a lamp that lights up when an alarm occurs to call the driver's attention. , and even warn you.

That is, as shown in FIG. 1, the main switch 21 turns on and off the display unit 21.
0 as well as the aforementioned environmental sensors 19, 20.
A switch 211 is provided to make settings determined by rainy weather, road surface conditions, etc. Also, a scale 212 of the inter-vehicle distance from 0 meters to 100 meters, for example.
Below the scale 212, a variable inter-vehicle distance indicator provides the inter-vehicle distance to the vehicle in front at any time during driving, for example, by color-coded display. The calculation of the inter-vehicle distance will be described later.

Two types of pointers are provided above the scale 212 as warning distance variable indicators, one of which, the pointer 213, indicates the safe distance between the vehicle in front and the vehicle traveling at the current speed in the current environment. It shows the minimum distance and also
The other pointer 214 indicates the inter-vehicle distance that is dangerous under the current environment and vehicle speed. Therefore, when the distance between vehicles is equal to or greater than the minimum safe distance between the two cars, the vehicle is in a sufficiently safe driving state, and when the distance approaches the minimum distance between the two cars, the vehicle is moving out of the safe distance range. This indicates the first warning distance, and if the distance is shorter than the guideline 214, it becomes a dangerous distance (second warning distance).

Alarms can be generated in various ways; for example, as shown in the figure, the primary alarm lamp 215 and secondary alarm lamp 216 may be colored and turned on or blinking, or a buzzer may be sounded gradually louder from the primary alarm to the secondary alarm. There are methods such as gradually shortening the intermittent ringing time of the buzzer sound. Figure 1
217 is an on/off switch for determining whether or not to generate a primary alarm and secondary alarm.

The inter-vehicle distance display and the pointers 213 and 214 change at any time depending on environmental changes and vehicle speed. By simply determining whether the vehicle is on the left side, the current following distance can be easily determined from moment to moment.

Next, the calculation process leading to the generation of an alarm by the apparatus of this embodiment will be explained with reference to FIG. The distance between the host vehicle 12 and the vehicle in front 22, that is, the inter-vehicle distance D (m), is determined by the laser radar unit 1 as described above. The own vehicle speed Vf (m/s) is detected by the vehicle speed sensor 17. The speed of the vehicle in front 22, Va (m/s), is calculated from the change in inter-vehicle distance D per minute time. That is, the front vehicle speed Va is determined from the relative speed between the own vehicle 12 and the front vehicle 22. On the other hand, the time it takes for the driver to decide that it is dangerous and press the brake pedal, that is, the idle running time Td (S), and the time that the driver decides that it is dangerous, that is, the judgment time Tx (s
), the deceleration α1 (m/s2) of the own vehicle, and the deceleration α2 (m/s2) of the vehicle in front are stored in the memory of the control unit 14 in advance. Decelerations α1 and α2 are stored with values assuming full braking, and usually α1 =
It is assumed to be α2.

[0021] The braking distance L1 of the front vehicle 22 is calculated from the above-mentioned front vehicle speed Va and deceleration α2 as follows: L1 = Va2/2α2
It is determined by The idle running distance L2 of the own vehicle 12 is determined from the own vehicle speed Vf, the idle running time Td, and the judgment time Tx, L2 = (
Td+Tx)Vf. Braking distance L of own vehicle 12
3 is L3 = V from own vehicle speed Vf and deceleration α1
It is determined by f2/2α1.

Therefore, as a condition for generating an alarm, the sum of the braking distance L1 of the preceding vehicle and the inter-vehicle distance D is equal to the braking distance L of the own vehicle.
3 and the vehicle's empty running distance L2. In other words, the following equation is obtained.

(Va2/2α2)+D<(Vf2/2α1)+(
Td+Tx)VfD<(Td+Tx)Vf+(Vf2/
2α1 − Va2/2α2)=Ds (safe inter-vehicle distance) Therefore, Ds is displayed by the pointer 213, and D<D
s, the display unit 21 displays the first
An alarm is generated and, for example, the first alarm lamp 215 is turned on.

As can be seen from this equation, the safe inter-vehicle distance D
Since the speed of the vehicle in front 22 is taken into consideration in calculating s, the speed of the vehicle in front 22
The optimum warning time is determined depending on whether the vehicle is running at high speed or low speed, whether it is accelerating or decelerating, and whether the vehicle is stopped or not. When the vehicle in front 22 is stopped, Va=0 in the formula.

By the way, the decelerations α1 and α2 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 19 has been turned on, the control unit 14 changes the numerical values of the decelerations α1 and α2 and changes the alarm generation inter-vehicle distance. In other words, on wet roads, the pointer will automatically move to 2.
The safe inter-vehicle distance Ds displayed by 13 changes, and the warning generation timing is brought forward. For example, the deceleration α on a dry road
If 1 (=α2) is about 0.3G, then depending on the road condition, it will be 0.2G (for example, a wet road), 0.1
G (for example, on frozen roads, snowy roads, etc.).

Furthermore, when driving on a turning road on a highway, the laser beams 16a,
If the detection area of the vehicle in front 22 by 16b and 16c is set aside, the reflector of the guardrail will be detected, and the alarm will be issued frequently even though there is no need to issue an alarm. This actually distracts the driver's attention. Therefore, in the turning path, the area (warning judgment area) where the laser beams 16a, 16b, and 16c detect whether or not there is a vehicle ahead is changed to an area where the reflector of the guardrail is not detected. That is, as shown in FIG. 7, the warning judgment areas Sl,
Sc and Sr are changed. The radius of road curvature R of the turning path 34 is determined from the steering angle detected by the steering sensor 18, and based on this, the relationship between the radius of road curvature R and the warning judgment area S determined in advance is determined from the relationship (FIG. 8). The alarm determination area of each laser beam 16a, 16b, 16c is determined.

Next, a specific example of control by the control unit 14 in the apparatus of this embodiment will be explained based on the flowchart of FIG. First, initial values are set in step (1). In other words, the idle running time Td, the judgment time Tx, the deceleration α of the own vehicle 12 and the vehicle 22 in front when the vehicle is fully braked.
1, α2 (α1 = α2) are set. While the truck 12 is running, the inter-vehicle distance D is calculated in step (2) based on the above-mentioned calculation formula, and in step (3) the vehicle speed Vf is calculated by the vehicle speed sensor 17.
is detected, and in step (4), the front vehicle speed Va is determined 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 20 or the like (step (5)). For example, it is detected whether the wiper switch 19 is in the ON state.

Next, the decelerations α1 and α2 of the own vehicle and the vehicle in front
is changed according to the road surface condition (step (6)
). If no environmental information is detected in the previous step (5), the initially set decelerations α1 and α2 are used as they are.

Next, in step (7), the own vehicle speed Vf, the front vehicle speed Va,
The safe inter-vehicle distance Ds is determined from the decelerations α1, α2, etc. This safe inter-vehicle distance Ds takes into consideration the speed of the vehicle 22 in front and is appropriately modified according to the road surface conditions.

On the other hand, the steering angle is detected by the steering sensor 18 (step (8)), and then in step (9) it is determined whether the steering wheel is in the neutral position, that is, whether the vehicle is traveling straight or turning. . If the steering wheel is in the neutral position,
Proceeding to step (13), it is determined whether the current inter-vehicle distance D is within the safe inter-vehicle distance Ds. Safe following distance D
If the distance is within s, the display unit 21 determines the safe inter-vehicle distance.

If it is determined in step (13) that the inter-vehicle distance D is smaller than the safe inter-vehicle distance Ds, then in step (14) the speed of the preceding vehicle Va and the own vehicle speed Vf are compared. If the front vehicle speed Va is high, the inter-vehicle distance D is increasing, so there is no need to issue a warning, and the process moves to step (12). If the front vehicle speed Va is smaller than the own vehicle speed Vf, it means that the vehicle is in the warning area and is gradually approaching, so a warning generation command is issued to the display unit 21, a warning is issued, and , the inter-vehicle distance D is also displayed.

On the other hand, if it is determined in step (8) above that the steering wheel is not in the neutral position,
Since the vehicle is turning, the warning determination areas Sl, Sc, and Sr for each of the laser beams 16a, 16b, and 16c are determined from the map 33 shown in FIGS. 8 and 9 based on the turning direction and steering angle. In other words, as shown in Figure 7, the distance is limited and objects beyond that distance are not read. This operation is handled by not performing distance detection if the time it takes for the laser beam to return is longer than a certain time.

Next, the inter-vehicle distance D and warning judgment areas Sl, S
c, Sr (step (11)), and inter-vehicle distance D
is larger than the alarm determination ranges Sl, Sc, and Sr, the process moves to step (12) and no alarm is generated. If the inter-vehicle distance D is smaller than the warning determination areas Sl, Sc, Sr, it is determined in the next step (12) whether the inter-vehicle distance D is greater than the safe inter-vehicle distance Ds. Note that the reason why the inter-vehicle distance D is compared with all the warning determination areas Sl, Sc, and Sr in step (11) is to also detect an intervening vehicle.

From step (13) onwards, comparison and judgment processing is performed in the same manner as described above. The above calculations are repeated while the truck 12 is running.

[0036] Also, in order to generate an alarm in stages, a second
In this embodiment, the next alarm is set using the pointer 214. For example, D
<Ds, the buzzer will sound several times as the first alarm (caution alarm), and the second alarm will be issued when D<Td.
Vf+(Vf2/2α1 −Va2/2α2)=Ds1
In this case, the secondary alarm lamp 21
6 is turned on and, for example, a buzzer sounds continuously. This state does not require the driver's judgment, but rather requires the driver to step on the brakes immediately. If warnings are issued in stages, drivers can respond more quickly.

[0037]

[Effects of the Invention] As explained above, according to the inter-vehicle distance display/warning device according to the present invention, the driver can visually confirm the inter-vehicle distance display well in advance, and the warning can be predicted. Braking can be performed quickly without panic.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an example of a display device.

FIG. 2 is a schematic diagram of the device configuration.

FIG. 3 is an explanatory diagram of the schematic positional relationship of each component.

FIG. 4 is an explanatory diagram of a laser radar unit.

FIG. 5 is a plan view of the beam light emitting state.

FIG. 6 is an explanatory diagram of inter-vehicle distance, braking distance, etc.

FIG. 7 is an explanatory diagram showing how the warning judgment area is restricted when traveling on a turning route.

FIG. 8 is a diagram showing the relationship between road curvature radius and warning determination area.

FIG. 9 is a flowchart of one embodiment.

[Explanation of symbols]

1 Laser radar unit 12 Own car 14 Control unit 17 Vehicle speed sensor 18 Steering sensor 19 Wiper switch 20 Environmental sensor 21 Display unit 210 Main switch 211 Switch 212 Scale 213,214 Guidelines 215 Primary alarm lamp 216 Secondary alarm lamp

Claims (1)

[Claims] [Claim 1] The time required for the laser beam emitted from the own vehicle to be reflected by the vehicle in front and returned to the vehicle is detected to determine and display the inter-vehicle distance, and this inter-vehicle distance is the braking distance and free running distance of the own vehicle. The following distance display/warning device is designed to issue a warning when the following distance is smaller than the safe following distance determined based on An inter-vehicle distance display/warning device characterized by having a variable warning distance indicator between the vehicle and the vehicle.