JP2904318B2 - Rear-end collision warning system for automobiles - Google Patents

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 device for an automobile.

[0002]

2. Description of the Related Art Such an apparatus is known (see Japanese Utility Model Application Laid-Open No. 63-24700 by the present applicant and a preprinted collection 881 of the Society of Automotive Engineers of Japan).

The latter device will be described with reference to FIGS. 5 to 8. The device is a laser radar head 1 which is a distance detecting means attached to a first cross member 7, and an inter-vehicle distance signal from the head 1. And an information processing device 3 for calculating a safe inter-vehicle distance from the relative speed of the preceding vehicle B and the own vehicle A obtained by a temporal change in the inter-vehicle distance and the speed of the own vehicle A by the vehicle speed sensor 5 as a vehicle speed detecting means. , Distance display device 2 that performs distance display using a signal from information processing device 3
And a display switch box 4 having an input section for issuing an alarm and operating a variable switch by a driver, and a monitor output circuit 6.

The laser radar head 1 irradiates a laser beam C forward as shown in FIG. 7 and measures the inter-vehicle distance D from the time when the reflected light C ₁ from the reflector 8 of the preceding vehicle B returns. I do. Here, V ₁自 own vehicle speed V ₂先行 preceding vehicle speed α ₁自 braking deceleration of own vehicle α ₂の braking deceleration of preceding vehicle Dr 安全 safe inter-vehicle distance Ds: Safe inter-vehicle distance when the preceding vehicle stops Td: Free running time (fixed to 1 second, for example) Tx: Judgment time until braking operation occurs (variable) Ty: Advance When the car stopped at the time of the judgment time _{(variable), 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.

In FIG. 8, initialization is performed (step S ₁ ), and based on a signal from the vehicle speed sensor 5, the own vehicle speed V _{1 is set.}
Is calculated (step S ₂ ), and the inter-vehicle distance D is calculated and added based on the signal from the radar head 1 (step S ₃ ). Next, the ON / OFF position of each switch of Tx, Ty, α ₁ and α ₂ is input every 10 milliseconds (steps S ₄ and S ₅ ). Next, a signal from the radar head 1 is input for 100 milliseconds, and if 50% or more of the reflected light C1 is returned during this time, it is determined that the target is being detected, and the average value of the distance data during that time is obtained. Further, the relative speed between the own vehicle A and the preceding vehicle B is calculated from the change in the distance by the least square method. In addition, a distinction between the moving object and the stopping object is determined based on the absolute speed value of the preceding vehicle B obtained by adding the speed of the vehicle A and the relative speed obtained by the calculation (step S).
_6, S _7). Next, according to equations (1) and (2), Dr, D
s is calculated (step S ₈ ), and D <Dr or D <Ds
Output to the alarm lamp (Step S ₉₎ when, with output to the monitor (step S _10), performs control to return to step S2, thereby achieving the prevention of rear-end collision.

[0007]

In the conventional apparatus of the conventional problems of the Related Art above safe distance D _R in the preceding vehicle traveling is defined by equation (1), in this assumption, the mobile object (safe distance (1) equation applied) and stopping the object to determine the absolute velocity V ₂ of the preceding vehicle B the distinction (safe distance (2) apply) (V ₂
Is substantially equal to 0), the continuity of the values of the expressions (1) and (2) at the time of determination (it can be called a difference) is high,
There was no driver discomfort with the switching of the formula itself. However, there arises a problem in the practicality of the expression (1) itself, and accordingly, a problem also arises in determining the distinction between the expressions (1) and (2) based on the absolute speed of the preceding vehicle B. Was. When formula (1) is put to practical use, if a warning is issued at a safe inter-vehicle distance that takes into account the braking distance V ₂ / 2α ₂ of the preceding vehicle that is not normally conscious of the driver, the driver will be surprised. This causes a sense of incongruity with the driving sensation of the driver, and as a result, distrust of the alarm device.

[0008] As another known technique, Japanese Patent Publication No. 55-1
Japanese Patent No. 5337 discloses a technique for judging danger by judging whether an object is a stationary or moving object based on a difference between a relative speed between the own vehicle and the object and a speed of the own vehicle. However, such a known technique is to calculate the required minimum inter-vehicle distance based on the ground speed or the relative speed and issue an alarm, so that time is not considered, for example, the operation time for the braking operation is not considered, Further, as described above, the driver may feel uncomfortable with driving. Further, Japanese Patent Application Laid-Open No. Sho 62-130599 discloses a technique in which an alarm generation distance varies depending on a relative speed. However, this technique is intended to prevent false alarms caused by a roadside reflector or the like on a curved road, and does not improve the driver's uncomfortable feeling with respect to a preceding vehicle.

[0009]

For this reason, the present inventor has conducted various studies and found that the braking distance of the preceding vehicle is an uncertain factor for the driver. It turns out that they think they are almost the same. Therefore, for the moving body, the equation Dr = V ₁ (Td + Tx) (Td + Tx), excluding the terms relating to the braking distance (assuming V ₁ = V ₂ and α ₁ = α ₂ ) from equation (1). 3) used, also with respect to the stationary body, to consider using _{Ds = V 1 (Td + Ty} ) + V 1 2 / 2α 1 ··· (4).

[0010] As a result, the (3) and (4) when using, differences between these two formulas (V ₁ ² / 2.alpha ₁₎
Is the difference between the expressions (1) and (2) (V ₂ ² / 2α ₂ ,
However, when the difference is mentioned, V ₂ is close to zero. )
Therefore, according to the prior art, the driver is relatively unaware of the absolute speed of the preceding vehicle.

Therefore, when various experiments were conducted, the above (3)
It has been found that when the switching work of the equations (4) and (4) is switched by the relative speed between the own vehicle and the preceding vehicle, an alarm can be generated without a feeling of strangeness.

[0012]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a rear-end collision warning device for an automobile which does not cause any discomfort during actual driving.

[0013]

According to the present invention, a vehicle speed detecting means and a distance detecting means are provided, the distance detecting means comprising a radar head, and signals detected by the vehicle speed detecting means and the distance detecting means are inputted. A vehicle collision calculation device for calculating a vehicle speed based on a vehicle speed signal from the vehicle speed detection means. A distance calculation circuit that calculates an inter-vehicle distance based on a distance signal from the distance detection means; and a relative speed calculation circuit that calculates a relative speed between the host vehicle and an object from a change in the inter-vehicle distance. The relative speed signal from the circuit is 50
When the speed is equal to or less than about km / h, the first object is determined to be a moving object, and a first alarm issuance distance is calculated based on the own vehicle speed, idle running time, and a determination time until a braking operation is performed. When the relative speed signal from the vehicle is about 50 km / h or more, the object is determined to be a stationary object, and based on the own vehicle speed, the idle running time, the determination time when the preceding vehicle is stopped, and the braking deceleration of the own vehicle, A safe inter-vehicle distance calculating circuit for calculating a second alarm generating distance different from the first alarm generating distance; and an alarm when the inter-vehicle distance calculated by the distance calculating circuit becomes smaller than the first or second alarm generating distance. An alarm generation judging circuit for outputting to the generation means, wherein the first alarm generation distance is determined by the idling time, the judgment time until the control operation is performed, and the vehicle speed, and the second alarm generation distance is determined by the idling speed. Time, judgment time when the preceding vehicle is stopped, own vehicle speed, and It is adapted to be determined by the braking deceleration of. Further, according to the present invention, a vehicle speed detecting means and a distance detecting means are provided, the distance detecting means comprises a radar head, and an information processing device to which signals detected by the vehicle speed detecting means and the distance detecting means are inputted, In a rear-end collision warning device for an automobile, provided with an alarm generating means that operates by an output from the information processing device, a self-vehicle speed calculation circuit for calculating a self-vehicle speed based on a vehicle speed signal from the vehicle speed detection means, and a distance from the distance detection means. A distance calculation circuit that calculates an inter-vehicle distance by a signal, and a relative speed calculation circuit that calculates a relative speed between the own vehicle and the object from the change in the inter-vehicle distance are provided, and a change in the own vehicle speed from the own vehicle speed calculation circuit is provided. It is determined whether or not the vehicle is accelerating. If the determination is that the vehicle is accelerating, the second speed is determined if the relative speed signal from the relative speed calculation circuit is equal to or greater than a predetermined value.
When the relative speed signal from the relative speed calculation circuit is not larger than a predetermined value, a first alarm generation distance different from that of the second alarm generation distance calculation circuit is calculated, and If the relative speed signal from the relative speed calculation circuit is not lower than a predetermined value obtained by subtracting a fixed value from the predetermined value when the speed is not increasing, the second alarm generation distance is calculated, and When the relative speed signal is not greater than the lower predetermined value, a safety inter-vehicle distance calculation circuit that calculates a first alarm generation distance, and the inter-vehicle distance calculated by the distance calculation circuit is greater than the first or second alarm generation distance. And an alarm generation determining circuit for outputting the alarm generation means to the alarm generation means when it becomes smaller.

[0014]

According to the present invention, when the relative speed with respect to the preceding vehicle is larger than a predetermined value, that is, when the vehicle is approaching rapidly (a stationary body), the vehicle speed, idle running time, and braking operation are performed. In the case where a warning is issued from a relatively long distance by the first warning generation distance calculated based on the determination time of and the relative speed is smaller than a predetermined value, that is, when the vehicle slowly approaches (for a moving body), The second calculated on the basis of the own vehicle speed, the idling time, the judgment time when the preceding vehicle is stopped, and the braking deceleration of the own vehicle
The alarm is issued after relatively approaching according to the alarm generation distance. The driver usually pays attention to the relative speed with respect to the preceding vehicle under driving consciousness when driving, and issues an alarm at the required minimum inter-vehicle distance based on the theoretical value introducing the braking distance of the preceding vehicle, Driving feeling and discomfort are caused. Therefore, in the present invention, an alarm is issued in accordance with the actual driving feeling, and an alarm without discomfort is obtained. Further, according to the present invention, the hysteresis is provided so that the switching determination between the first alarm generation distance and the second alarm generation distance is performed at a predetermined lower value lower than the speed increase when the speed increase is not being performed. Therefore, occurrence of so-called hunting, which is repeated switching, is prevented.

That is, according to the present invention, since the relative speed is used, it is determined whether the vehicle is approaching quickly or slowly. Therefore,
In the present specification, except for the description of the related art, a stationary body means an object which is in a close approach (approaching speed or a predetermined value or more), and a moving body means an object in a slow approaching (an approach speed is equal to or less than a predetermined value). I have.

[0016]

Preferred Embodiment In carrying out the present invention, the predetermined value of the relative speed is preferably about 50 km / h. The upper limit of the safe inter-vehicle distance is fixed to 80 m for a moving object, and the upper limit for a stationary object is a range that can be detected by radar.
It is preferably fixed at 0 m. Further, it is preferable to issue different alarms for a stationary body and a mobile body.

[0017]

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

In FIG. 1, the rear-end collision warning device includes a laser radar head 1, a vehicle speed sensor 5, a distance display device 2, a warning buzzer 9, an information processing device 10 in the illustrated example.
Each device is arranged in the same manner as in FIG. 5 described above.

The information processing apparatus 10 is constituted by a microcomputer, and calculates an own vehicle speed V ₁ based on a vehicle speed signal from a vehicle speed sensor 5, and a signal from the laser radar head 1 based on a signal from the laser radar head 1. A distance calculation circuit 12 for calculating an inter-vehicle distance D, a relative speed calculation circuit 13 for calculating a relative speed Vc between the host vehicle and the object based on a signal from the circuit 12, and a signal based on a signal from the circuit 13. ,
When the relative speed Vc is equal to or less than a predetermined value (for example, 50 km / h), the target object is determined to be a moving object (preceding vehicle), and based on the own vehicle speed (V ₁ ) signal from the own vehicle speed calculation circuit 11, Expression (3) Calculates the first alarm generation distance Dr, calculates the second alarm generation distance Ds according to equation (4), determines that the target object is a stationary object when the relative speed is equal to or more than a predetermined value, and calculates the second alarm generation distance Ds according to equation (4). 14 and the signals from the two circuits 12 and 14, when it is determined that the inter-vehicle distance D is smaller than the first or second alarm generation distances Dr and Ds, it is determined that an audio alarm is generated. And an alarm occurrence determination circuit 15 for outputting a control signal. Note that the alarm can be issued by, for example, blinking of a red lamp.

At the time of control, as shown in FIG. 2, the information processing apparatus 10 performs an initial setting such as a predetermined relative speed value (for example, 50 km / h) (step S ₁ ), and based on a signal from the vehicle speed sensor 5, The vehicle speed calculation circuit 11 calculates the vehicle speed V ₁ (step S ₂ ), and the distance calculation circuit 12 calculates and inputs the inter-vehicle distance D based on the signal from the laser radar head 1 (step S ₃ ). Then, enter Tx, alpha ₁ of the ON · OFF position of the switches every 10 milliseconds (step S _4, S _5). Then, the distance to the signal input 100 milliseconds from the calculating circuit 12 in the radar head 1, it is determined that during this time there is a target object if me is returned reflected wave C ₁ of 50% or more, the inter-vehicle from the distance between them data the average value of the distance D, also, the relative speed calculation circuit 13 calculates the relative speed Vc of the vehicle and the object from the change in the distance by the method of least squares (step S _6, S _7). Next, based on the signal from the relative speed calculation circuit 13, the safety inter-vehicle distance calculation circuit 14 determines that the relative speed Vc is a predetermined value (for example, 50 km).
/ H) determined is smaller than or not (step S _11).
You were YES, subject is determined to the preceding vehicle in which or mobile body based on the signal from vehicle speed calculation circuit 11 calculates the first alarm distance Dr by the formula (3) (Step S _12). Therefore, the alarm generation determination circuit 15 determines whether or not the inter-vehicle distance D is smaller than the first alarm generation distance Dr based on the signals from both circuits 12 and 14 (Step S).
_13), in the case of NO end control, it was YES, the output control signals to the alarm buzzer 9, to generate an alarm (step S _16), ends the control.

[0021] the other hand, if step S ₁₁ is NO, and determines that the object is a stationary body, calculating a second alarm distance Ds by the formula (4) (step S _14). Therefore, the alarm generation determination circuit 15 determines whether the inter-vehicle distance D is smaller than the second alarm generation distance Ds (step S ₁₅ ).
For O the end of the control, you were YES, then generating an alarm from the alarm buzzer 9 (Step S _16), ends the control.

FIG. 3 shows another embodiment of the control mode. That is, the information processing apparatus 10 to the next step S _7, vehicle speed changes in vehicle speed calculated by the calculation circuit 11 (step S _17), the safe inter-vehicle distance calculation circuit based on the calculation signal 14 vehicle speed increasing It is determined whether the vehicle is in the middle or not (step S ₁₈ ). If YES, the relative speed Vc becomes the predetermined value 50 km.
/ H is determined (step S ₁₉ ).
It was S, the second alarm distance Ds calculated (step S _20), if NO, to calculate the first alarm distance Dr (Step S _22). On the other hand, step S ₁₈ is NO
In the case of (deceleration), the relative speed Vc is a predetermined lower value (for example, 45 km / h) obtained by subtracting a constant value (for example, 5 km / h) from the predetermined value.
miles / h) determines larger or not (step S _24). You were YES, the second alarm distance Ds calculated (step S _25), if NO, to calculate the first alarm distance Dr (Step S _27). Therefore, the alarm generation determination circuit 15 determines that the inter-vehicle distance D is the second based on signals from the safe inter-vehicle distance calculation circuit 14 and the distance calculation circuit 12.
The alarm distance Ds or determines first alarm distance or Dr smaller (Step _{S 21, S 23, S 26} ,
S _28). If NO, end the control, if YES,
Outputs a control signal to the alarm buzzer 9 to generate an alarm (step S _29), ends the control.

As a result, in the control flow shown in FIG. 2, as shown in FIG. 4, the relative speed Vc is set at a predetermined value (50 km / h) regardless of the acceleration / deceleration of the own vehicle. (4) Switching to (Ds) and hunting while the alarm occurrence distance flies discontinuously in the boundary condition at the time of switching, whereas a predetermined lower value (45 km / h) during deceleration
Hysteresis can be provided by switching in order to prevent hunting.

[0024]

As described above, according to the present invention, when the relative speed with respect to the preceding vehicle is higher than the predetermined value, the vehicle approaches rapidly, so that a warning is issued from a relatively distant place, and when the relative speed is lower than the predetermined value. , A warning is issued after a relatively close approach. In other words, instead of determining whether the target vehicle is stopped or running based on the absolute speed, it is determined separately based on the relative speed and the rapid approach including stop, the slow approach, so if you select an appropriate value for the predetermined value, There is no uncomfortable feeling in the judgment. At this time, the alarm generation distance, that is, the safe inter-vehicle distance, in the case of a sudden approach, the first alarm generation distance calculated based on the own vehicle speed, the idle running time, and the determination time until the braking operation is performed, Further, in the case of a gentle approach, the second warning issuance distance calculated by adding the braking distance of the own vehicle to the distance based on the own vehicle speed, the idle running time, and the determination time when the preceding vehicle is stopped, so that a more secure And an alarm suitable for the actual driving feeling is issued. Normally, the vehicle is controlled by the relative speed with respect to the preceding vehicle that the driver is consciously driving, and the driver may be surprised by an alarm that takes into account the braking distance of the preceding vehicle that the driver is not conscious of. Therefore, there is no possibility of distrust of the alarm device due to discomfort with the driving feeling. Further, according to the present invention, the hysteresis is provided so that the switching determination between the first alarm generation distance and the second alarm generation distance is performed at a predetermined lower value lower than at the time of speed increase when the speed increase is not being performed. Therefore, occurrence of so-called hunting is prevented.

As described above, it is reasonable to judge the danger to the preceding vehicle, and the setting of Dr and Ds can be simplified.
Control is also easy.

[Brief description of the drawings]

FIG. 1 is a control block diagram showing one embodiment of the present invention.

FIG. 2 is a control flowchart showing an example of a control mode according to the present invention.

FIG. 3 is a control flowchart showing another control mode.

FIG. 4 is a control characteristic diagram when the present invention is implemented.

FIG. 5 is a side view of an automobile provided with a conventional rear-end collision warning device.

FIG. 6 is a control block diagram of a conventional rear-end collision warning device.

FIG. 7 is an explanatory diagram of a rear-end collision warning device.

FIG. 8 is a flowchart of a conventional rear-end collision warning device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Laser radar head 5 ... Vehicle speed sensor 9 ... Warning buzzer 10 ... Information processing device 11 ... Own vehicle speed calculation circuit 13 ... Relative speed calculation circuit 14 ... Safe inter-vehicle Distance calculation circuit

Continuation of the front page (56) References JP-A-59-53995 (JP, A) JP-A-62-130500 (JP, A) JP-A-57-157400 (JP, A) JP-A-61-162778 (JP) JP-A-56-157647 (JP, A) JP-A-52-124628 (JP, A) JP-A-60-91500 (JP, A) JP-B-55-15337 (JP, B2) 53-25315 (JP, Y2)

Claims (2)

(57) [Claims] 1. A vehicle comprising a vehicle speed detecting means and a distance detecting means,
The distance detecting means comprises a radar head, comprises an information processing device to which signals detected by the vehicle speed detecting means and the distance detecting means are inputted, and is provided with an alarm generating means which is activated by an output from the information processing device. In a rear-end collision warning device, a vehicle speed calculation circuit that calculates a vehicle speed based on a vehicle speed signal from the vehicle speed detection unit, a distance calculation circuit that calculates an inter-vehicle distance based on a distance signal from the distance detection unit, and a change in the inter-vehicle distance. A relative speed calculating circuit for calculating a relative speed between the own vehicle and the object; and when a relative speed signal from the relative speed calculating circuit is about 50 km / h or less, the object is determined to be a moving body and the own vehicle speed is determined. Calculating the first alarm generation distance based on the idle running time and the judgment time until the braking operation is performed. The relative speed signal from the relative speed calculation circuit is 50 k.
When the speed is about m / h or more, the object is determined to be a stationary body, and the first alarm generation distance is determined based on the own vehicle speed, idle running time, determination time when the preceding vehicle is stopped, and braking deceleration of the own vehicle. Different second
Safety inter-vehicle distance calculation circuit for calculating the alarm generation distance of the vehicle, and an alarm generation determination circuit for outputting to the alarm generation means when the inter-vehicle distance calculated by the distance calculation circuit becomes smaller than the first or second alarm generation distance. The first alarm generation distance is determined by an idle running time, a determination time until a control operation is performed, and the vehicle speed, and the second alarm generation distance is an idle running time and a determination time when the preceding vehicle is stopped. A rear-end collision warning device for a vehicle, wherein the rear-end collision warning device is determined by a vehicle speed and a braking deceleration of the vehicle. 2. A vehicle comprising a vehicle speed detecting means and a distance detecting means,
The distance detecting means comprises a radar head, comprises an information processing device to which signals detected by the vehicle speed detecting means and the distance detecting means are inputted, and is provided with an alarm generating means which is activated by an output from the information processing device. In a rear-end collision warning device, a vehicle speed calculation circuit that calculates a vehicle speed based on a vehicle speed signal from the vehicle speed detection unit, a distance calculation circuit that calculates an inter-vehicle distance based on a distance signal from the distance detection unit, and a change in the inter-vehicle distance. A relative speed calculation circuit for calculating a relative speed between the own vehicle and the object; and determining whether or not the own vehicle is accelerating based on a change in the own vehicle speed from the own vehicle speed calculation circuit. In the case of, when the relative speed signal from the relative speed calculation circuit is equal to or more than a predetermined value, the second alarm generation distance is calculated, and when the relative speed signal from the relative speed calculation circuit is not larger than the predetermined value, The first alarm generation distance different from the second alarm generation distance calculation circuit is calculated, and when the determination is not in the process of increasing the speed, the relative speed signal from the relative speed calculation circuit is set to a fixed value from the predetermined value. When the distance is equal to or greater than the reduced lower predetermined value, the second alarm generation distance is calculated. When the relative speed signal from the relative speed calculation circuit is not larger than the lower predetermined value, the first alarm generation distance is calculated. A calculation circuit; and an alarm generation determination circuit that outputs to the alarm generation means when the inter-vehicle distance calculated by the distance calculation circuit becomes smaller than the first or second alarm generation distance. Rear-end collision warning device for automobiles.