JPH05453Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] The present invention relates to a rear-end collision warning system for automobiles.

[Prior Art] Such a device is known (see Japanese Utility Model Application Publication No. 1983-24700 by the present applicant and Society of Automotive Engineers of Japan Academic Lecture Preprint Collection 881. 1986-5).

The latter device will be explained with reference to FIGS. 3 to 6. This device includes a laser/radar head 1 which is a distance detection means attached to a first cross member 7, and receives an inter-vehicle distance signal from the head 1. Leading vehicle B obtained by changing the inter-vehicle distance over time
and an information processing device 3 that calculates a safe inter-vehicle distance from the relative speed of the vehicle A and the speed of the vehicle A detected by the vehicle speed sensor 5, which is a vehicle speed detection means, and a distance display that displays the distance using a signal from the information processing device 3. a display switch box 4 that issues an alarm and has an input section for the driver to operate a variable switch;
and a monitor output circuit 6.

The laser/radar head 1 irradiates a laser beam C forward as shown in FIG. 6, and measures the inter-vehicle distance D from the time when the reflected light _C1 from the reflector 8 of the preceding vehicle B returns. Here, V ₁ ... Speed of own vehicle V ₂ ... Speed of preceding vehicle α ₁ ... Braking deceleration of own vehicle α ₂ ... Braking deceleration of preceding vehicle Dr ... Safe inter-vehicle distance (while the preceding vehicle is running) Ds ...Safe inter-vehicle distance when the preceding vehicle is stopped Td...Dry running time (fixed to 1 second, for example) Tx...Judgment time until braking action (variable) Ty...Judgment time when the preceding vehicle is stopped (variable) Then, Dy=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) shown.

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

That is, in FIG. 6, initial settings are performed (step S ₁ ), vehicle speed V ₁ is calculated based on the signal from the vehicle speed sensor 5 (step S ₂ ), and inter-vehicle distance D is calculated based on the signal from the radar head 1. Calculate and add (step _S3 ). Then, Tx, Ty, α ₁ , α ₂
The ON/OFF position of each switch is input every 10 milliseconds (steps _S4 and _S5 ). Next, the signal from radar head 1 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 object has been detected, and the average value of the distance data during that time is calculated. , the relative speed between own vehicle A and preceding vehicle B is calculated from the change in distance using the least squares method. Furthermore, the distinction between a moving object and a stationary object is determined based on the absolute speed value of the preceding vehicle B, which is obtained by adding the speed of own vehicle A and the calculated relative speed (steps S ₆ and S ₇ ). . Next, Dr, Ds by equations (1) and (2)
is calculated (step S ₈ ), and when D<Dr or D<Ds, it is output to the warning lamp (step S ₉ ), output to the monitor (step S ₁₀ ), and the control returns to step S2 to prevent a rear-end collision. We are trying to prevent this.

[Problems with the conventional technology] However, in the conventional technology, the braking distance V ₂ ² /2α ₂ of the preceding vehicle is included as a factor in the safe inter-vehicle distance Dr, and when this factor is taken into account, There is a problem in that the driver of the vehicle lacks a concept of the braking distance of the preceding vehicle, and as a result, the driving sensation feels strange when the warning occurs.

In addition, although it is generally desirable to drive while maintaining the following distance for safety, in actual driving, the following distance is often reduced due to the traffic environment, and in this case, the warning frequency is high. In addition, if the volume is high, there is a problem that the alarm becomes noisy and becomes less effective as people become accustomed to the alarm.

Furthermore, Japanese Patent Publication No. 58-56837 discloses a technique for issuing warnings at different frequencies in response to multiple levels of danger. However, in this known technique, when the own vehicle speed is kept constant, the frequency varies depending on whether the relative distance is near or far from the end, so some drivers may feel that the driving interval is strange.

[Problems to be Solved] Therefore, the purpose of the present invention is to use an alarm to inform the driver of the safe following distance that is determined from the driver's ability or vehicle performance and that is acceptable to the driver.
Furthermore, it is an object of the present invention to provide a rear-end collision warning system for a motor vehicle that can issue a strong warning to a driver who is traveling by reducing the distance between vehicles in consideration of the traffic environment, etc., thereby increasing the warning effect.

[Means for Solving the Problems] A rear-end collision warning system for a motor vehicle according to the present invention includes a vehicle speed detection means and a distance detection means consisting of a radar head, and an automatic vehicle speed detection system that calculates the own vehicle speed based on a vehicle speed signal from the vehicle speed detection means. A vehicle speed calculating circuit, a safe following distance calculating circuit that calculates a safe following distance from the own vehicle speed and calculating a dangerous following distance by multiplying the own vehicle speed by a constant rate, and 2 or more types of safe following distances that differ depending on the safe following distance and the dangerous following distance. An alarm occurrence determination circuit is provided to determine the occurrence of an alarm, and the alarm occurrence determination circuit issues a loud audible warning when the following distance is less than a predetermined value, and when the following distance is greater than the predetermined value, it is less than the safe following distance and is dangerous. If the distance is greater than the following distance, a small audio warning will be issued.
It has a function that issues a loud warning when the distance is less than the dangerous following distance.

[Explanation of Effects] In equation (1) above, the braking distance of the preceding vehicle was used as a factor, but as mentioned above, this is not in the driver's consciousness, so it is difficult to convince the driver. Therefore, in this invention, the judgment is made only based on the own vehicle speed. Therefore, the safe inter-vehicle distance is Dr = V ₁ (Td + Tx) ... (3) or Dr = V ₁ (Tα + Tx) + V ₁ ² /2α ₁ ... (3a) Therefore, the own vehicle speed, which is the feeling of normal driving. Since a safe distance between vehicles is determined based on the distance, there is no discomfort when the warning is issued. However, this alone does not determine the braking distance of the preceding vehicle, so it is not safe in the event that the preceding vehicle brakes suddenly. Therefore, a dangerous following distance is set which is smaller than the safe following distance and is always within the driver's awareness, multiplying the own vehicle speed by a fixed rate, and if the vehicle approaches the dangerous following distance, a warning different from the safe following distance warning will be issued. If this is done, it will be rational for the driver to recognize the danger.

Here, it is preferable to use Dd=0.5TxV ₁ (4) with a constant rate of 0.5Tx for the dangerous inter-vehicle distance Dd.

Furthermore, it is preferable to issue a warning regardless of the vehicle speed when the inter-vehicle distance is less than a predetermined value (for example, 12 m). When the inter-vehicle distance D is smaller than the safe inter-vehicle distance Dr, for example, a small audio warning can be issued, and when it is smaller than the dangerous inter-vehicle distance Dd, for example, a loud audio warning can be issued.

Therefore, the driver can receive a warning that matches his/her actual driving sensation.

[Examples] Examples of the present invention will be described below with reference to the drawings.

In FIG. 1, the rear-end collision warning system is composed of a laser/radar head 1 using a laser, a vehicle speed sensor 5, a distance display device 2, a warning buzzer 9, and an information processing unit 10. is the third
They are arranged as shown in the figure.

The information processing device 10 is composed of a microcomputer, and has a vehicle speed calculation circuit 11 that calculates the vehicle speed V ₁ based on a vehicle speed signal from the vehicle speed sensor 5.
and a safe inter-vehicle distance calculation circuit 12 which calculates a safe inter-vehicle distance Dr from the own vehicle speed V ₁ by equation (3) and a dangerous inter-vehicle distance Dd by equation (4), and a safe inter-vehicle distance calculation circuit 12 based on the signal from the laser/radar head. Based on the calculation results of both circuits 12 and 13, the distance calculation circuit 13 calculates the inter-vehicle distance D based on the calculation results of the two circuits 12 and 13.
It is determined that a small sound alarm will be generated when the level is below Dr.
Alarm generation in which it is determined that a loud audio warning will be generated when the inter-vehicle distance D is less than or equal to the dangerous inter-vehicle distance Dd, and that a loud audio warning will be generated when the inter-vehicle distance D is less than a predetermined value S (for example, 12 m) regardless of the vehicle speed. Based on the determination result of the alarm generation determination circuit 14, the alarm generation buzzer 9 generates two different types of audio warnings, a small sound and a loud sound. However, it is obvious that, for example, the constant rate may be changed to three or more types.

During control, as shown in FIG.
(seconds), Tx, and a constant rate (for example, 0.5Tx) (step S ₁ ). Based on the signal from the vehicle speed sensor 5, the own vehicle speed calculation circuit 11 calculates the own vehicle speed Vf (step S ₂ ). Based on the signal from the vehicle, the distance calculation circuit 13 calculates and adds the inter-vehicle distance D (step S ₃ ). Next, the ON/OFF positions of the Tx and _α1 switches are input every 10 milliseconds (steps S ₄ and S ₅ ). Next, the distance calculation circuit 13 inputs the signal from the radar head 1 for 100 milliseconds, and if more than 50% of the reflected light _C1 is returned during this period, it is determined that there is a preceding vehicle B, and the distance between the vehicles is calculated based on the distance data during that time. The average value of the distance D is determined (steps S ₆ and S ₁₁ ). Next, safe inter-vehicle distance calculation circuit 1
2, Dr = V ₁ (Td + Tx) + V ₁ ² /2α ₁ is the safe inter-vehicle distance Dr, and Dd = 0.5TxVf, the dangerous inter-vehicle distance Dd
(Step _S12 ). Next, the alarm generation determination circuit 14 determines whether the inter-vehicle distance D is less than a predetermined value S (step _S13 ), and if YES, outputs a control signal to the alarm generation buzzer 9 to generate a loud alarm. Then (step _S17 ) the control ends, and if NO, it is determined whether the inter-vehicle distance D is smaller than the safe inter-vehicle distance Dr (step _S14 ). If NO,
When the control is finished and the answer is YES, it is determined whether the inter-vehicle distance D is smaller than the dangerous inter-vehicle distance Dd (step _S15 ). If NO, a small audible alarm is generated (step _S16 ) and the control is terminated; if YES, a loud audible alarm is generated (step _S17 ) and the control is terminated.

In this way, by issuing two different types of warnings depending on the vehicle speed and inter-vehicle distance, it is possible to obtain a warning that does not give a sense of discomfort to the driver, and the different types of warnings improve the warning effect.

[Effects of the invention] As described above, according to the invention, even if the driver is unconscious, that is, looking away or driving carelessly, it is possible to predict danger in the same way as when the driver is conscious.
At safe following distances, a weaker warning is issued, which reduces the noise and annoyance, but still calls for caution. In addition, in the case of a dangerous inter-vehicle distance, for example, a strong warning is issued so that the driver can immediately take a braking action, thereby eliminating the sense of discomfort in driving and increasing the effectiveness of the warning.

[Brief explanation of the drawing]

1 and 2 are a control block diagram and a control flowchart showing one embodiment of the present invention, and FIGS. 3, 4, 5, and 6 are an overall configuration diagram and control diagram of a conventional device, respectively. They are a block diagram, an operation explanatory diagram, and a control flowchart. DESCRIPTION OF SYMBOLS 1... Laser/radar head, 5... Vehicle speed sensor, 9... Warning generation buzzer, 10... Information processing device, 11... Own vehicle speed calculation circuit, 12... Braking distance calculation circuit, 14... Alarm generation determination circuit .

Claims (1)

[Scope of utility model registration request] A vehicle speed calculation circuit that includes a vehicle speed detection means and a distance detection means consisting of a radar head, calculates the vehicle speed based on the vehicle speed signal from the vehicle speed detection means, and calculates a safe inter-vehicle distance from the vehicle speed and calculates the vehicle speed based on the vehicle speed signal from the vehicle speed detection means. A safe inter-vehicle distance calculation circuit that calculates a dangerous inter-vehicle distance by multiplying by a fixed rate, and an alarm occurrence determination circuit that determines the occurrence of two or more different types of alarms depending on the safe inter-vehicle distance and the dangerous inter-vehicle distance, are provided, and the alarm occurrence determination circuit is provided. will issue a loud audible warning when the following distance is less than a predetermined value.
A vehicle characterized by having a function of emitting a small audio warning when the inter-vehicle distance is equal to or greater than a predetermined value but smaller than the safe inter-vehicle distance and greater than the dangerous inter-vehicle distance, and emitting a loud audio warning when it is less than the dangerous inter-vehicle distance. Rear-end collision warning system.