JPH0644500A - Rear-end collision alarming device for automobile - Google Patents

Abstract

PURPOSE:To give an alarm in a state desirable for a driving feeling by discriminating a safe distance between an own automobile and the one in front and varying discrimination time for performing a breaking operation. CONSTITUTION:An information processor 10 performs initial setting such as free running period of time or the like, calculates an own automobile speed by an own automobile speed calculation circuit 11 based on signals from a speed sensor 5 and calculates the distance between the automobiles by a distance calculation circuit 12 based on the signals from a laser/rader head 1 to be added. When reflected waves whose reflection echo is more than 50% of transmission light return during the period of time, the presence of a preceding automobile is discriminated and the average value of the distance between the automobiles is obtained from distance data during the period of time. Then, a safe distance between automobile calculation circuit 13 calculates the safe distance between the automobiles based on the signals from the circuit 11 and a switch 4A. Succeedingly, an alarm generation discrimination circuit 14 outputs control signals to an alarming buzzer 9 and generates the alarm when the distance between the automobiles is shorter than the safe distance between the automobiles based on the signals from the circuits 12 and 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear-end collision warning system for automobiles.

[0002]

2. Description of the Related Art Such a device is known (see Japanese Utility Model Application Laid-Open No. 63-24700 and Preprints 881 of the Society of Automotive Engineers of Japan, Showa 63-5).

The latter device will be described with reference to FIGS. 4 to 7. The device is a laser radar head 1 which is a distance detecting means attached to the first cross member 7.
And the relative speed between the preceding vehicle B and the own vehicle A obtained by receiving the inter-vehicle distance signal from the head 1 over time and the speed of the own vehicle A by the vehicle speed sensor 5 which is a vehicle speed detecting means. An information processing device 3 for calculating an inter-vehicle distance, a distance display device 2 for displaying a distance by a signal from the information processing device 3, a display switch box 4 for issuing an alarm and having an input section for a driver to operate a variable switch. , Monitor output circuit 6.

The laser radar head 1 irradiates a laser beam C forward as shown in FIG.
The inter-vehicle distance D is measured from the time when the reflected light C1 from the reflector 8 returns. Here, V ₁ ... own vehicle speed V ₂ ... preceding vehicle speed α ₁ ... own vehicle braking deceleration α ₂ ... preceding vehicle braking deceleration Dr ... safe inter-vehicle distance (preceding While driving the vehicle) Ds: Safe inter-vehicle distance when the preceding vehicle is stopped Td: Idle time (fixed at 1 second, for example) Tx: Judgment time (variable) before braking action Ty: Leading Assuming that the determination time (variable) when the vehicle is stopped is Dr = V ₁ (Td + Tx) + (V ₁ ² / 2α ₁ −V ₂ ² / 2α ₂ ) ... (1) Ds = V ₁ (Td + Ty) + V ₁ ² / 2α ₁ (2)

Therefore, an alarm is issued when D <Dr and D <Ds.

That is, in FIG. 7, initial setting is performed (step S ₁ ), the own vehicle speed V ₁ is calculated based on the signal from the vehicle speed sensor 5 (step S ₂ ), and the radar head 1
Signal and adds calculated inter-vehicle distance D based on from (Step S _3). Next, the ON / OFF positions of the Tx, Ty, α ₁ and α ₂ switches are input every 10 milliseconds (steps S ₄ and S ₅ ). Next, the radar head 1
Signal is input for 100 milliseconds, and if 50% or more of the reflected light C1 is returned during this period, it is determined that the target object is detected, the average value of the distance data during that period is calculated, and the least squares method is used. The relative speed between the own vehicle A and the preceding vehicle B is calculated from the change in the distance. Further, the distinction between the moving object and the stopped object is determined based on the absolute speed value of the preceding vehicle B obtained by adding the speed of the own vehicle A and the calculated relative speed (steps S ₆ and S ₇ ). . Then, according to equations (1) and (2), D
r, Ds are calculated (step S ₈ ), and D <Dr or D
When <Ds, output to alarm lamp (step S ₉ ),
And output to the monitor (step S _10), performs control to return to step S2, thereby achieving the prevention of rear-end collision.

[0007]

[Problems of the Prior Art] In the above-mentioned conventional device, the braking distance of the preceding vehicle is included in the safety inter-vehicle distance expression (1) while the preceding vehicle is running. Since the driver has no idea about the braking distance of the vehicle, and the alarm is triggered by a matter outside the driver's consciousness, the driver feels uncomfortable and, on the contrary, feels uncomfortable with the normal driving sensation and, in turn, distrusts the alarm device. There was a problem in practice. Further, normally, the safe inter-vehicle distance described in, for example, a driving school is calculated by setting the braking distance of the preceding vehicle to zero in the above formula (1). In some cases, the alarm became too large and the alarms occurred frequently, causing problems in practical use.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rear-end collision warning device for a vehicle which eliminates the above-mentioned problems and secures a function for enhancing traveling safety, and which is comfortable to use and has no discomfort in driving sense. Has an aim.

[0009]

According to the present invention, a vehicle speed calculating circuit which includes a vehicle speed detecting means and a distance detecting means composed of a radar head, and calculates a vehicle speed based on a vehicle speed signal from the vehicle speed detecting means. And an alarm distance variable switch that changes the free running time and the judgment time until the braking action occurs,
A safe inter-vehicle distance calculating circuit that calculates a safe inter-vehicle distance based on the vehicle speed and a signal from the alarm distance variable switch, and a small value by judging whether the inter-vehicle distance is smaller than the safe inter-vehicle distance calculated by the safe inter-vehicle distance calculating circuit. In this case, an alarm occurrence determination circuit for issuing an alarm is provided.

[0010]

The preferred inter-vehicle distance Dri is Dri = Vf (Td + Txi) from the vehicle speed Vf, free running time Td (fixed at 1 second, for example), and judgment time Tx (variable) until braking operation.・ ・ Given in (3).

[0011] Here, Txi is, for example, Txs ... to speed up the alarm generation, Txm ... to normalize the alarm generation, Tx. It is set in series and the safe inter-vehicle distances Drs, Drm, Dr
Is preferred.

[0012]

[Description of Operation and Effects] Therefore, if the driver sets the warning distance variable switch so as to suit his / her driving feeling / appropriateness and driving environment in advance, the driver can issue a warning without feeling uncomfortable.

In the present invention, the safe inter-vehicle distance is judged by the own vehicle speed without considering the braking distances of the own vehicle and the preceding vehicle as the judgment reference, and the judgment time for performing the braking operation is variable.
Since the alarm is issued in a drivingly preferable state and the braking distance of the preceding vehicle which is practically unpredictable is not determined, the control device can be rationalized.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, the rear-end collision prevention device is a laser radar head 1 using a laser in the illustrated example, a vehicle speed sensor 5, a distance display device 2, an alarm issuing device, that is, an alarm issuing buzzer in the illustrated example. 9, an alarm distance variable switch 4A, and an information processing device 10. The switch 4A has a determination time Txi until a braking operation is initiated.
As described above, for example, 3 of Txs, Txm, Tx
You can choose the seed. However, two or four or more types may be selected.

FIG. 2 is a block diagram in which the present invention is embodied. The information processing device 10 is composed of a microcomputer, and based on the vehicle speed signal from the vehicle speed sensor 5, the own vehicle speed Vf.
A vehicle speed calculation circuit 11 for calculating the distance, a distance calculation circuit 12 for calculating an inter-vehicle distance D based on a signal from the laser radar head 1, the circuit 11 and an alarm distance variable switch 4
Based on the signal from A, the safe inter-vehicle distance D is calculated according to equation (3).
Safety inter-vehicle distance calculation circuit 13 for calculating ri and both circuits 1
Based on the signals from 2 and 13, an alarm device, that is, an alarm generation determination circuit 14 that outputs a control signal to the alarm generation buzzer 9 in the illustrated example, is provided when the inter-vehicle distance D becomes smaller than the safe inter-vehicle distance. .

Next, the operation will be described with reference to FIG. The information processing device 10 performs initial settings such as free running time (fixed at 1 second, for example) (step S ₁ ), and calculates the own vehicle speed Vf by the own vehicle speed calculation circuit 11 based on the signal from the vehicle speed sensor 5 ( step S _2), based on a signal from the laser radar head 1, the distance calculating circuit 12 to the inter-vehicle distance D calculated added in (step S _3). As described above, this addition operation is performed, for example, every 10 milliseconds for 100 milliseconds. That is, the selected value Txs or T of the alarm distance variable switch 4A
xm or Tx (step S ₄ ) is input every 10 milliseconds (step S ₅ ), and the signal from the radar head 1 is input to the distance calculation circuit 12 for 100 milliseconds (step S ₆ ). During this period, the reflection echo is 50% against the transmitted light.
Determines that there is a preceding vehicle if me is returned or reflected waves C1, an average value of inter-vehicle distance D from the distance between them data (step S _11). Next, safety inter-vehicle distance calculation circuit 1
3 denotes signals Vf and Tx from the circuit 11 and the switch 4A.
Based on i, the safe inter-vehicle distance Dri is calculated by the equation (3) (step S ₁₂ ). Next, the alarm occurrence determination circuit 14
Determines whether the inter-vehicle distance D is smaller than the safe inter-vehicle distance Dri based on the signals from the circuits 12 and ₁₃ (step S ₁₃ ). If NO, the process returns to step S ₂ , and if YES, an alarm is issued. outputs a control signal to the buzzer 9, to generate an alarm (step S _14), the flow returns to step S _2.

[0018]

As described above, according to the present invention, since an alarm is issued by the own vehicle speed and the alarm distance variable switch that changes the judgment time, the judgment of the control device can be simplified and the driver can actually drive the vehicle. Therefore, it is possible to obtain an alarm which is not uncomfortable and which is suitable for one's sense and aptitude.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a control block diagram showing an example of a rear-end collision warning device embodying the present invention.

FIG. 3 is a control flowchart of FIG.

FIG. 4 is a side view of an automobile having a conventional rear-end collision warning device.

FIG. 5 is a conventional control block diagram.

FIG. 6 is an explanatory view of the operation of the rear-end collision warning device.

FIG. 7 is a flow chart of a rear-end collision warning device for Jipurai.

[Explanation of symbols]

 1 ... Laser radar head 4A ... Warning distance variable switch 5 ... Vehicle speed sensor 10 ... Information processing device 11 ... Own vehicle speed calculation circuit 12 ... Distance calculation circuit 13 ... Safety distance Distance calculation circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G01S 17/88 A 4240-5J G08B 21/00 H 7319-5G

Claims (1)

[Claims] 1. A vehicle speed calculating circuit comprising a vehicle speed detecting means and a distance detecting means comprising a radar head, and a vehicle speed calculating circuit for calculating an own vehicle speed based on a vehicle speed signal from the vehicle speed detecting means, and an idle time and a braking operation. Variable distance switch that changes the judgment time until the safety distance between the vehicle and the safe distance between the vehicle and the signal from the variable distance switch, and the safety distance between the distance calculated by the safety distance calculation circuit A rear-end collision warning device for a vehicle, comprising: an alarm generation determination circuit that determines whether or not the distance is shorter than the inter-vehicle distance and issues an alarm if the distance is smaller.