JPH06103500A - Intervehicle distance alarm device - Google Patents

Abstract

PURPOSE:To judge the steepness of a road and to suppress the generation of an intervehicle distance alarm by stopping the generation of the alarm for a certain period of time or during the period of a certain traveling distance when the average value of the product of a handle angle and lateral acceleration exceeds a prescribed threshold value. CONSTITUTION:A control unit 14 calculates a curving degree and the curving degree is the quantified value of the steepness of the road, in other words, of the busyness of a handle operation and also, the average of the product of the handle angle and the lateral acceleration in a certain period of time. Then, the value of the curved angle is compared with a prescribed threshold value 5 every second for instance, and the sounding of the alarm by an alarm generator 24 is stopped for 15 seconds thereafter in the case when the value is equal to or more than the prescribed threshold value 5. Also, in the case when the value of the curved angle is less than the prescribed threshold value 5, the alarm is sounded if conditions for sounding the alarm are satisfied. That is, in the case when the road is steep to the extent that the curved angle exceeds the prescribed threshold value 5, it is considered that the handle operation is busy and dozing off or the like can not occur, and the sounding of the alarm is stopped.

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 a 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 on highways are
The majority of drivers are drowsy driving and aimless driving.
Under these circumstances, we have developed a vehicle-to-vehicle distance detection / alarm system that detects the vehicle-to-vehicle distance between the vehicle and the front vehicle and alerts the driver when the distance falls below a certain distance. Has been done. The outline of the conventional device is that laser light is emitted forward from the vehicle, and the laser light is reflected by the reflector on the rear surface of the front vehicle. The inter-vehicle distance is calculated from the distance, and when the inter-vehicle distance becomes equal to or less than a predetermined distance, the buzzer in the vehicle interior is sounded.

In such an inter-vehicle distance / warning device, a method of preventing misidentification in which a stopped object existing at a certain interval is not judged as a front vehicle so that a warning is not generated by erroneously recognizing a guardrail reflector, a sign, etc. as a front vehicle. (Japanese Patent Laid-Open No. 62-13050
No. 0), and a range cut method has been proposed in which the range cut processing is performed to limit the range of the object to be measured according to the steering wheel angle and the ground speed, thereby reducing the frequency of erroneous detection.

[0004]

However, according to the above-mentioned conventional method, there are things that do not exist at regular intervals, such as rocks, guardrails, forests, and quiver boards. There is a risk that a vehicle that is not determined to be the wrong vehicle may be mistakenly recognized as a preceding vehicle and an alarm may be issued. Further, when entering a curve, when exiting the curve, or when the turning radius changes during the curve, particularly when the steering wheel is busy, such as on a mountain road, the range cut process may not be properly performed, and an alarm may be frequently issued. . Such false alarms not only significantly reduce the reliability of the alarm, but also reduce the effectiveness of the alarm due to habituation to the alarm. On the other hand, on mountain roads, the frequency of steering and pedal operation by the driver is high and the risk of falling asleep etc. is low, so it is considered desirable to suppress the generation of warnings as much as possible. The present invention has been made in view of the above-mentioned conventional art, and suppresses the generation of an inter-vehicle distance warning by determining the road steepness (flexing degree) when the steering wheel is busy, such as in a mountain road. It is an object of the present invention to provide an inter-vehicle distance warning device that can be operated.

[0005]

The structure of the present invention which achieves such an object detects the inter-vehicle distance between a front vehicle and a host vehicle, and when the inter-vehicle distance becomes smaller than a safety inter-vehicle distance previously obtained. In an inter-vehicle distance warning device that issues an alarm, if the average value of the product of steering wheel angle and lateral acceleration, the average value of steering wheel angle or the average value of lateral acceleration exceeds a predetermined threshold, a certain period of time from Or during a certain mileage,
It is characterized in that the generation of the alarm is stopped.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of an inter-vehicle distance warning device which is the premise of the present invention will be described with reference to FIG. Reference numeral 1 denotes a laser radar unit incorporated in a front bumper of a vehicle or the like, which includes a light emitting portion 2 and a light receiving portion 3 as shown in FIG. The light emitting section 2 is composed of a laser diode drive circuit 4, a laser diode 5, and a light emitting lens 6, and emits a laser beam 7 in a pulse shape at regular time intervals. The light receiving unit 3 includes a light receiving lens 9 that receives the laser beam reflected by the reflector 8a of the front vehicle 8, a photodiode 10, an amplifier 11, a signal processor 12, and the like. An inter-vehicle distance D (= (Δt / 2) × light speed) is obtained by the distance detection circuit 13 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 inter-vehicle distance signal that is the detection value of the laser radar unit 1 is
It is input to the control unit 14 mounted on the vehicle.

Information such as the vehicle speed, the steering wheel angle, and the turn signal of the vehicle is also input to the control unit 14. A block diagram of sensors for that purpose is shown in FIG. As shown in this figure, an inter-vehicle distance sensor 15 including the distance detection circuit 13 described above, a vehicle speed sensor 16 for detecting the vehicle speed of the host vehicle, a steering wheel angle sensor 17, a turn signal switch 18, a stop lamp switch 19, and the like are provided. Signals from these sensors 16 and the like are sent to the control unit 14
Is input to the calculation unit 21 of.

The calculation unit 21 determines whether or not an alarm should be issued based on the input signals from the sensors 15 and 16 and the like, taking into consideration the degree of bending. That is, as described above, the distance between the host vehicle and the front vehicle 8 (inter-vehicle distance D (m)) is obtained by the inter-vehicle distance sensor 15, and the own vehicle speed Vf (m
/ S) is detected by the vehicle speed sensor 16, and the speed Va (m / s) of the front vehicle 8 is calculated from the change in the inter-vehicle distance D per minute time. On the other hand, the time until the driver determines that the driver is dangerous and depresses the brake pedal, that is, the free running time Td (s), the time when the driver determines that the driver is dangerous, that is, the determination time Tx (s) and the deceleration of the vehicle. α ₁ (m / s ² )
The deceleration α ₂ (m / s ² ) of the front vehicle is stored in the memory of the control unit 14 in advance. Deceleration α ₁ ,
For α _2, the value assuming full braking is stored, and normally,
α ₁ = α ₂ .

The braking distance L ₁ of the front vehicle 8 is equal to the front vehicle speed V
From a and deceleration α _2, it can be obtained by L ₁ = Va ² / 2α ₂ . The free-running distance L ₂ of the vehicle is determined by the vehicle speed Vf and the free-running time T.
From d and the judgment time Tx, L ₂ = (Td + Tx) Vf can be obtained. The braking distance L ₃ of the own vehicle is obtained by L ₃ = Vf ² / 2α ₁ from the own vehicle speed Vf and the deceleration α 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 /
When 2α ₂ ) = Ds (safe inter-vehicle distance), it is determined that the alarm is to be issued.

In the present embodiment, the above calculation is not performed each time, and an alarm is issued based on the relationship between the vehicle speed Vf and the relative speed (speed difference between the preceding vehicle and the vehicle) dv as shown in FIG. The generation distance is obtained as a map 23 and is read. The result read from the map 23 is input to the alarm generator 24. The alarm generator 24 uses the alarm lamp 2
4a, an alarm buzzer 24b, an inter-vehicle distance display panel 24c and the like.

The alarm is issued in two stages. For example, when became D <Ds, as described above with the primary ^{alarm, D <TdVf + (Vf 2} / 2α 1 -Va 2 / 2α 2) =
A secondary alarm is issued when Ds ₁ is closer. For the primary alarm, the alarm lamp 24a is turned on and the alarm buzzer is turned on.
Blow only once. In the case of the secondary alarm, the alarm lamp 2
4a is made to blink and an alarm buzzer is intermittently sounded.

Next, the bending degree K is calculated by the following equation. The bending degree K is a quantification of the steepness of the road, in other words, the busyness of the steering wheel operation, and is an average of the product of the steering wheel angle and the lateral acceleration for a certain period of time. The degree of bending is calculated every 1 second for the effective value for the past 20 seconds. K = {(1/20) ΣHi ² · Gi ² } ^1/2 where Σ is the sum of i = 0 to 19 and K is the degree of bending (g · de
g) and Hi are steering wheel angles (deg) i seconds ago, and Gi is lateral acceleration (g) i seconds ago. Here, the reason why Hi and Gi are squared to find the square root thereof is that Hi and Gi take negative values, and therefore, they are absolute values.

The lateral acceleration can be calculated by the following equation. However, it is also possible to detect by a lateral acceleration sensor. Gi = δ / [9.8 ・ 57.3 ・ L ・ ρ ・ {A + (1 /
Vf ² )}] where Vf is the vehicle speed (m / sec), δ is the steering wheel angle (deg), A is the stability factor, L is the wheel base (m), and ρ is the steering wheel equivalent gear ratio.

The value of the bending degree K thus obtained is 1
It is compared with a predetermined threshold value 5 every second, and when it is equal to or larger than the predetermined threshold value 5, the alarm generation is stopped for the subsequent 15 seconds. When the value of the bending degree K is less than the predetermined threshold value 5, the alarm is issued when the condition for the alarm is satisfied as described above. That is, the bending degree K is a predetermined threshold value 5
If the road is steep enough to exceed the threshold, the steering wheel operation is too busy and there is no danger of falling asleep and the alarm is stopped. Further, in the case where the turning radius changes during a curve such as in a mountain road, even if the range cut processing is performed, it is not possible to sufficiently prevent the false alarm, so that the alarm is stopped.

Here, since the bending degree K uses an average value, it is considered that there is no abrupt change when the handle is operated to some extent. Thus, in this embodiment,
Since the frequency of false alarms on rugged roads such as mountainous roads decreases, the reliability and effectiveness of the alarms increase, contributing to safer driving.

In the present embodiment, the mean value of the product of the steering wheel angle and the lateral acceleration is used as the bending degree K, but the present invention is not limited to this. The steering wheel angle and the lateral acceleration have a relationship that if one becomes larger, the other also becomes larger.
The bending degree K may be obtained by using the average value of the steering wheel angle or the average value of the lateral acceleration. Also, the averaging time is not limited to the above-mentioned 20 seconds, but for example, about 5 seconds or more is a good guideline.

Further, the predetermined threshold value of the bending degree K is set to 5 in the above example, but it should be appropriately changed according to road surface conditions, climatic conditions, types of vehicles, and the like.
In the above embodiment, the alarm is stopped for 15 seconds after the degree of flexion exceeds a predetermined threshold value. However, the alarm may be stopped for a certain distance. .

[0019]

As described above in detail with reference to the embodiments, the present invention determines the steepness (bending degree) of the road when the steering operation is busy such as a mountain road, and determines the distance between vehicles. It is possible to suppress the generation of the distance warning. As a result, the frequency of false alarms is reduced, the reliability and effectiveness of alarms are increased, and this further contributes to safe driving.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an inter-vehicle distance warning device to which the present invention is applied.

FIG. 2 is an explanatory diagram of a laser radar unit.

FIG. 3 is a block diagram showing an outline of a control unit.

FIG. 4 is an inter-vehicle distance warning map for obtaining an alarm generation distance from a vehicle speed and a relative speed.

[Explanation of symbols]

 1 Laser Radar Unit 2 Light Emitting Section 3 Light Receiving Section 4 Laser Diode Driving Circuit 5 Laser Diode 6 Light Emitting Lens 7 Laser Beam 8 Front Vehicle 9 Light Receiving Lens 10 Photodiode 11 Amplifier 12 Signal Processor 13 Distance Detection Circuit 14 Control Unit 15 Distance Sensor 16 Vehicle speed sensor 17 Steering wheel angle sensor 18 Turn signal switch 19 Stop lamp switch 21 Computation unit 23 Inter-vehicle distance warning map 24 Alarm generator

Claims (3)

[Claims] 1. An inter-vehicle distance warning device for detecting an inter-vehicle distance between a front vehicle and a host vehicle, and issuing an alarm when the inter-vehicle distance becomes smaller than a previously determined safe inter-vehicle distance. An inter-vehicle distance warning device, wherein when the average value of the products of the lateral acceleration exceeds a predetermined threshold value, the generation of the warning is stopped for a certain period of time or a certain mileage from the time of exceeding. 2. An inter-vehicle distance warning device, which detects an inter-vehicle distance between a front vehicle and an own vehicle, and issues an alarm when the inter-vehicle distance becomes smaller than a safety inter-vehicle distance previously obtained, An inter-vehicle distance warning device, wherein when the average value exceeds a predetermined threshold value, the generation of the alarm is stopped for a certain period of time or a certain mileage from the time when the average value exceeds the predetermined value. 3. An inter-vehicle distance warning device, which detects an inter-vehicle distance between a front vehicle and an own vehicle, and issues an alarm when the inter-vehicle distance becomes smaller than a previously determined safe inter-vehicle distance. If the average value exceeds a predetermined threshold,
An inter-vehicle distance warning device, characterized in that the generation of the warning is stopped for a certain period of time or a certain mileage from the time when the vehicle exceeds the limit.