JPH04201642A - Between-vehicle distance detecting alarm device - Google Patents

Abstract

PURPOSE:To properly generate alarm even in the traveling on a low mu road surface such as on a wet road surface in the rainy weather, by changing the alarm generation timing according to the road surface state judged on the basis of the result of the detection of an environmental sensor. CONSTITUTION:The between-vehicle distance D is calculated during the traveling of a truck 12, and the own vehicle speed Vf is detected by a car speed sensor 17, and the speed Va of the preceding vehicle is obtained through the variation of the between-vehicle distance D and the own vehicle speed Vf. While, the advance state of the own vehicle 12 is detected by a steering sensor 18, and the alarm judging distance S is determined. Then, the road surface state is judged on the basis of the results of the detection by a wiper switch and other environmental sensors, and the safe between-vehicle distance Ds is calculated through the change to each deceleration speed alpha1, alpha2 corresponding to the road surface state. Then, the between-vehicle distance D and the alarm judging distance S are compared.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides an inter-vehicle distance system that detects the inter-vehicle distance between one's own vehicle and the vehicle in front, and issues an alarm when the distance becomes less than a certain distance. More specifically, the present invention relates to a detection/warning device that takes into account the condition of the road surface.

<Conventional Technology> The majority of rear-end collisions involving trucks are caused by drivers falling asleep or driving distracted. Due to these circumstances, there are currently inter-vehicle distance detection/warning devices that detect the distance between the own vehicle and the vehicle in front and issue a warning to the driver when the distance falls below a certain distance. being developed. The outline of the current version of this device is that it emits a laser beam in front of the vehicle, receives the laser beam that is reflected by the rear flap of the vehicle in front, and calculates the distance between the vehicles based on the time. When the following distance is reached or less than a predetermined distance, a buzzer inside the vehicle will sound.

<Invention or problem to be solved> By the way, the deceleration of a car when the brakes are applied changes depending on the road surface condition. For example, when driving on a wet road in rainy weather, the deceleration is smaller than when driving on a dry road in sunny weather. If the road is icy or frozen, the deceleration will be even smaller.

However, current inter-vehicle distance detection/warning devices do not change the warning distance depending on road conditions.

Means for Solving the Problems> In order to solve the above problems, the present invention detects the time it takes for a laser beam emitted from the own vehicle to be reflected by the vehicle in front and returns, and calculates the inter-vehicle distance. Inter-vehicle distance or braking distance of your vehicle,
In the following distance detection/warning device, which issues an alarm when the distance is less than a predetermined distance determined based on the free running distance, the road surface condition is detected by an environmental sensor, and the braking distance is determined according to the detected road surface condition. They changed the timing of the warning to be issued.

As the environmental sensor, a wiper switch, a raindrop sensor, etc. are used to detect rainy weather. Also,
A G sensor or the like is used to detect that the road is icy, and a temperature sensor is used as an element to detect that the road is frozen.

According to the above-mentioned inter-vehicle distance detection/warning device, the timing at which the warning is issued is changed depending on the road surface condition determined based on the detection results of the environmental sensor. Even when the vehicle is driving on the road, the generation of the warning is not delayed and is optimized.

EMBODIMENTS FIG. 1 shows the configuration of an embodiment of the inter-vehicle distance detection/warning device according to the present invention, and FIG. 2 shows an outline of its mounting position.

1 is 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 emitting unit 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 the laser light reflected by the front vehicle's steering flap, 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 unit 2 and the light received by the light receiving unit 3, the inter-vehicle distance D (=T−X speed of light) is determined by the distance detection time Δ and the path 11.

Laser radar unit! An inter-vehicle distance signal, which is a detected value, is input to a control unit (14) built into the lower side of the seat (13) of the truck 12.

The laser radar unit l is assembled into the bumper 15 of the truck 12 as shown in FIG. Three laser beams 16a on the left, center, and right.

16b and 16c are emitted.

Reference numeral 17 denotes a vehicle speed sensor, which detects the vehicle speed from a rotating part of the transmission, etc. A detection signal from the vehicle speed sensor 17 is input to the vehicle control unit I4.

Reference numeral 18 denotes a steering sensor comprising a disk 19 provided on the steering column and a light emitting/light receiving section 20 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 2o include a raindrop sensor, a road surface sensor, a temperature sensor, a slip sensor, and the like. The rain sensor detects that it is raining, i.e. the road is wet, the road sensor detects whether the road is being steered or not, or other conditions, and the temperature sensor detects whether the road is steered or not. In combination with detection results from other sensors, the weather and road conditions, such as icy conditions, are detected.

According to the slip sensor, it is possible to determine whether the road surface is prone to slipping based on the difference in rotational speed between the front and rear wheels.
road or high μ road is detected. The detection results are input to the control unit 14.

21 is a display unit built into the instrument panel in front of the driver's seat, which displays the following distance,
It is equipped with a buzzer that issues an alarm and a lamp that flashes when an alarm occurs to alert and even warn the driver.

Next, the calculation process leading to the generation of an alarm by the device of this embodiment will be explained.

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 vehicle speed V f (m/s) is detected by the vehicle speed sensor 17 . The speed of the vehicle 22 in front is Va (m/s
) is calculated from the change in inter-vehicle distance per minute time.

On the other hand, the time until the driver deems it dangerous and depresses the brake pedal, that is, the idle running time Td (s), the time that the driver deems it dangerous, that is, the time of judgment @ T x (s), and the own vehicle's Deceleration α.

(m/s") and the deceleration αt (m/s") of the vehicle in front are stored in advance in the memory of the control unit 14.

Deceleration α1. α is stored as a value assuming full braking, and is normally set as α1=α2.

The braking distance L1 of the front vehicle 22 is determined from the speed Va of the front vehicle and the deceleration α, L=Va''/2αt i::.

The idle running distance of the own vehicle 12 is the own vehicle speed Vf and the idle running time T
d, from the judgment time Tx, L! = (T d+ T
x) Determined by V f.

The braking distance of the own vehicle 12 is the own vehicle speed Vf and the deceleration α1
It can be found from L3=Vf''/2α1.

Therefore, the condition for generating a warning is that the braking distance L of the vehicle in front is
The trigger is when the automatic braking distance becomes smaller than the sum of 1 and the following distance, or the sum of the own vehicle's free running distance. In other words, Va”/2a! + D< Vf”/2a
+ + (Td+Tx)Vf Therefore, D< (Td+Tx)Vf+ (Vf”/ 2a +
-Va''/2a t)=Ds (safe inter-vehicle distance), the display unit 21 issues an alarm and the lamp flashes.

However, on wet or frozen roads during rainy weather, the vehicle's deceleration is α3. α becomes smaller.

Therefore, when it is detected that the wiper switch 19 has been turned on, the control unit 14 controls the deceleration α3. Change the value of α2 and change the warning generation inter-vehicle distance. In other words, on wet roads, etc., the safe following distance will automatically change, and the warning will be issued earlier. For example, if the deceleration on a dry road is α1 (=α,) or about 0.3G, depending on the road condition, it will be 0.2G (for example, on a wet road), O, 1G (for example, on a frozen road, on a snowy road). It was changed to Michi nato).

Next, the control unit 14 in the device of this embodiment
A specific example of control will be explained based on the flowchart shown in FIG.

First, initial values are set in step (1). In other words, the idle running time Td, the judgment time Tx, the host vehicle 12 and the vehicle in front 2.
2, deceleration α1 during full braking. α, (α, = α,)
is set.

While the truck 12 is running, the following distance is calculated based on the above-mentioned calculation formula in step (2), and in step (3) the vehicle speed V is determined by the vehicle speed sensor 17.
f is detected, and in step (4), the speed Va of the front vehicle is determined from the change in the inter-vehicle distance and the own vehicle speed Vf.

On the other hand, the steering sensor 18 detects the traveling state of the host vehicle 12 (straight traveling state or turning state), and the warning judgment distance S is determined accordingly (STEERING (5)). In other words, the distance determined by the laser beam is changed depending on whether the vehicle is traveling straight or turning. When turning, guardrails, flaps, etc. are detected, so the judgment distance is shortened. If three laser beams are to be emitted, an alarm judgment distance S is set for each beam.

Next, the road surface condition is determined based on the detection results of the wiper switch 19 and other environmental sensors 20, and the deceleration α1. α, and calculate the safe inter-vehicle distance Ds (step (6)).

Next, in step (7), the inter-vehicle distance and the warning judgment distance S are compared. If the inter-vehicle distance is greater, no warning is generated and only the inter-vehicle distance is displayed on the display unit 21 (step (8)).

If the inter-vehicle distance is smaller than the warning judgment distance S, the following step (9) compares the inter-vehicle distance with the safe inter-vehicle distance Ds. If the following distance is greater, there is no need to issue a warning, and the process moves to step (8).

If the inter-vehicle distance is smaller than the safe inter-vehicle distance Ds, in the next step αα, the speed of the preceding vehicle Va and the own vehicle speed Vf are compared. If the speed Va of the front vehicle is high, the distance between the vehicles is increasing, so there is no need to issue a warning and the process moves to step (8).

If the speed of the preceding vehicle Va is less than or equal to the own vehicle speed Vf, the vehicle is within the warning distance, so the display unit 21 is commanded to generate a warning, and the warning is issued and the following distance is displayed.

Note that the above calculations are repeated while the truck 12 is running.

<Effects of the Invention> According to the inter-vehicle distance detection/warning device according to the present invention, since the inter-vehicle distance at which the warning is issued is changed according to the road surface condition, the warning delay does not occur even on roads that are prone to slipping during rainy weather. This also improves the driving feeling.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the device configuration according to an embodiment of the present invention, Fig. 2 is an explanatory diagram of the general positional relationship of each component, Fig. 3 is an explanatory diagram of the laser radar unit, and Fig. 4 is a beam FIG. 5 is a plan view of the light starting state, FIG. 5 is an explanatory diagram of inter-vehicle distance, braking distance, etc., and FIG. 6 is a flowchart of one embodiment. In the drawing, l is a laser radar unit, 12 is the own vehicle, 14 is a vehicle control unit, 16a, 16b, 16c are light beams, 17 is a vehicle speed sensor, 18 is a steering sensor, 19 is a wiper switch, 20 is an environment sensor , 21 is a display unit. Figure 1 Procedural amendment February 8, 1991

Claims (1)

[Claims] The inter-vehicle distance is calculated by detecting the time it takes for the laser beam emitted by the own vehicle to reflect off the vehicle in front and return. In the following distance detection/warning device, which issues an alarm when the following distance becomes smaller than the following distance, an environmental sensor detects the road surface condition, changes the braking distance according to the detected road surface condition, and changes the timing at which the warning is issued. An inter-vehicle distance detection/warning device characterized by: