JPH07100426B2 - Rear-end collision warning system for vehicles - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle rear-end collision warning device that detects the distance between a host vehicle and a vehicle ahead and issues an alarm when the distance is equal to or less than a safe inter-vehicle distance. .

<< Prior Art >> As a conventional rear-end collision warning device for this type of vehicle, for example, one disclosed in Japanese Patent Publication No. 47-22532 is known. In this example, two antennas receive reflected echoes. It is configured to determine whether or not the front vehicle is heading toward the host vehicle at that time based on the ratio of the reception angles, and if the front vehicle is heading in the host vehicle direction, issue an alarm for preventing a rear-end collision. ing.

For example, in FIG. 15, when two vehicles 51 and 52 are traveling in front of the radar vehicle 50 with different lanes,
When x and y are detected as the velocity vector at a certain point of 52, the velocity vector x of the vehicle 51 is directed toward the radar vehicle 50.
It is judged as a vehicle that may collide with 50.

<< Problems to be Solved by the Invention >> However, in the conventional device as described above, the vehicle simply detects the speed vector of the vehicle ahead at a certain time point, and if the speed vector points toward the host vehicle, the vehicle collides with the vehicle. Since it is only determined that there is a possibility that a vehicle is traveling on a curved road, a vehicle that is traveling in a lane different from the own vehicle may also be determined to be a vehicle that may collide and may give a false alarm. There was a problem.

To explain this again with reference to FIG. 15, the vehicle 51 is in the lane.
Traveling L _1, the radar vehicle 50 and the vehicle 52 is traveling on the next lane L _2. In this case, the vehicle to which the radar vehicle 50 may collide is the vehicle 52 traveling in the same lane, but in the conventional device as described above, the vehicle 51 is determined to be a vehicle that may collide. There was a problem in some cases.

In view of the above problems, the present invention provides a rear-end collision warning device for a vehicle, which determines that only a front vehicle on the same lane as the own vehicle is a rear-end collision possibility vehicle and can issue an accurate rear-end collision prevention warning. With the goal.

<< Means for Solving the Problems >> In order to achieve the above objects, the present invention is configured as shown in FIG.

In the figure, the distance detecting means a detects the distance between the own vehicle and the preceding vehicle.

The safe inter-vehicle distance calculating means b calculates the safe inter-vehicle distance while the vehicle is traveling.

The azimuth detecting means c detects the azimuth of the vehicle ahead of the own vehicle.

The locus data detection means d detects the front vehicle on the azimuth / distance coordinate based on the distance data to the front vehicle detected by the distance detection means a and the azimuth data of the front vehicle detected by the azimuth detection means c. The locus data is detected.

The approximate straight line calculating means e calculates an approximate straight line of a plurality of locus data detected by the locus data detecting means d every predetermined time.

In the lane identity determining means f, the traveling locus of the preceding vehicle and the traveling locus of the own vehicle are the same based on whether or not the approximate straight line calculated by the approximate straight line calculating means e passes near the origin on the coordinates. Sex has been determined.

In the warning means g, when the lane identity determining means f determines that the traveling lane of the preceding vehicle and the traveling lane of the own vehicle are the same, and the preceding vehicle detected by the distance detecting means a. When the distance to is less than or equal to the above safe inter-vehicle distance, an alarm is issued.

<< Operation >> In the present invention, a plurality of traveling locus data for the front vehicle is detected based on the distance data to the front vehicle detected by the distance detection means a and the azimuth data of the front vehicle detected by the azimuth detection means c. To do. Then, based on the plurality of locus data, an approximate straight line of the running locus of the preceding vehicle is calculated by a calculation method such as the least square method. Here, when this approximate straight line passes near the origin on the azimuth / distance coordinates, it is determined that the vehicle in front is on the same lane as the own vehicle.

The reason why the lane can be identified by whether or not the approximate straight line passes near the origin is as follows.

Now, as shown in FIG. 16, the radar vehicle 50 is on the origin and x
It is assumed that there is a front target T that moves in the arrow Z direction on a road L ₅ having a radius of curvature R offset by ΔR in the axial direction.

Here, as shown in FIG. 17, a perpendicular is drawn from the point A onto the OT, its foot is M, the distance between the radar vehicle 50 and the front target T is 1, and the front target T with respect to the front direction of the radar vehicle 50. When the angle of φ is φ, the following equations (1), (2) and (3) are obtained.

l = OM + MT (1) OM = (R-ΔR) sin φ (2) MT ² + (R-ΔR) ² cos ² φ = R ² (3) Therefore, from the above formulas (1), (2) and (3) The following equation (4) is obtained.

In this case, when the radar vehicle 50 and the front target T overlap (when a collision occurs), ΔR = 0, so that the equation (4) is expressed by the following equation (5).

l = 2Rsinφ (5) On the other hand, when considering the use situation of the radar on the highway,
Obstacles on the road need only be considered for targets within 15 ° of the front of the vehicle.

On the other hand, for angles of about 15 ° or less, the approximate expression of the following expression (6) is obtained.

sinXX (6) Therefore, from the above equations (4) and (5), when the front target T is not on the own lane, the locus becomes a hyperbola shown by the following equation (7).

On the other hand, when the front target T is on the own lane, its locus is represented by the following equation (8) and is a straight line passing through the origin.

l2Rφ (8) Therefore, if these two are clearly distinguished, there is a front obstacle on the lane and there is a possibility of a rear-end collision in the near future. It will be possible to identify the possibility.

<< Description of Embodiments >> Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram showing the basic configuration of the first embodiment of the present invention.

In the figure, a trigger pulse is sent from the trigger pulse generation circuit 6 to the laser diode drive circuit 5. Further, the laser diode drive signal generated by the laser diode drive circuit 5 is sent to the laser diode 4 to generate laser light. Next, the generated laser light is applied to the light-sending lens 3 to be converted into a desired shape, and further guided to the scanner 1 and reflected by the mirror 1a provided in the scanner 1 to the front of the vehicle. It is irradiated.

On the other hand, 2 is a scanner drive circuit for controlling the scanner 1,
This scanner drive circuit 2 detects the relative azimuth information of the front laser-detected object with respect to the vehicle, and
This azimuth information is configured to be sent to the microcomputer 13.

Further, the reflected light from the detection object in front is condensed on the light receiving element 9 via the light receiving lens 8 and is amplified by the amplifier 10.

A distance counting circuit to which the trigger pulse from the trigger pulse generating circuit 6 and the light receiving signal from the amplifier 10 are input
In 10, the input delay time of both signals is measured by the clock 12 so that the distance to the detection object in front can be obtained, and this distance signal is sent to the microcomputer 13.

Further, 14 is a vehicle speed sensor. As will be described later, in the microcomputer 13, from the vehicle speed sensor 14 and the azimuth signal of the front vehicle input from the scanner drive circuit 2, the distance signal to the front vehicle input from the distance counting circuit 11 The lane distinction between the own vehicle and the preceding vehicle is performed based on the input vehicle speed signal, and an alarm output is issued to the alarm means 15 when necessary.

Reference numeral 7 is a power supply circuit that supplies power to the laser diode drive circuit 5.

The above is the basic configuration of the present embodiment.

By the way, FIG. 3 shows a case where the radar vehicle 50 is traveling on the lane (overtaking lane) L _{3 in the} direction of arrow C, and the radar vehicle 50 approaches the vehicles A and B ahead. There is.
In this case, the vehicle A is traveling on the same lane L _{3 as the} radar vehicle 50, and the vehicle B is traveling on the adjacent lane (traveling lane) L ₄ of the radar vehicle 50. Therefore, even if the vehicle B and the radar vehicle 50 approach each other temporarily, the vehicle that may have a true rear-end collision with the radar vehicle 50 is the vehicle A traveling in the same lane.

Therefore, it is determined whether or not the lane in which the vehicle in front is traveling is the same as the lane in which the vehicle is traveling, and only when the vehicle is traveling in the same lane, the possibility of a rear-end collision is further determined. However, in this embodiment, a highly accurate alarm output for preventing a rear-end collision is issued.

By the way, FIG. 4 shows the traveling loci of the respective vehicles observed from the radar vehicle 50 side when the radar vehicles 50 approach the vehicles A and B as shown in FIG.

In the figure, the horizontal axis shows the direction θ of the front vehicle observed from the own vehicle, and the vertical axis shows the distance R between the own vehicle and the front vehicle.
The position data of the preceding vehicle at that time is indicated by coordinates (θ, R), and the own vehicle position is indicated by coordinates (θ, O).

Here, A ₀ is the locus of the vehicle A on the same lane L _{3 as the} own vehicle, and B ₀ is the locus of the vehicle B traveling on the adjacent lane L ₄ .

By the way, as is clear from the figure, the traveling locus A ₀ of the vehicle A traveling on the same lane L ₃ as the vehicle is a straight line passing through the origin, while the vehicle traveling on the adjacent lane L ₄ The traveling locus B ₀ of B largely deviates from the origin.

Therefore, whether or not the preceding vehicle is traveling in the same lane as the own vehicle is determined by detecting the trajectory of the preceding vehicle on the azimuth / distance coordinates and whether or not it passes near the origin. It would be good to make a distinction.

Incidentally, the detection of the traveling locus of the vehicle can be directly calculated by the microcomputer 13 based on the azimuth information θ and the distance information R input every unit time, but this makes the calculation very complicated.

Therefore, in this embodiment, a plurality of trajectory data (θ ₁ , R ₁ ), (θ ₂ , R ₂ ), ... (θ _n-1 ,
R _n-1 ), (θ _n, R _n ), find an approximate straight line of the running locus from these locus data by the method of least squares, etc., and check whether this straight line passes near the origin and identify the lane identity Is configured to determine

As a premise for such lane identity determination, the obtained trajectory data must be for the same vehicle, but this is because the vehicle moves at 100 km / h or less even on highways, so The maximum movable distance of the vehicle is calculated from the elapsed time at the time of this measurement, and considering the measurement error, if the current vehicle is within the maximum movable range from the previous measurement, it is determined that it is the trajectory data from the same vehicle. are doing.

Next, FIG. 5 schematically shows a method for discriminating lane identity as described above. In FIG. 5, a ₁ , a ₂ ,
Points a ₃ and a ₄ are trajectory data of the vehicle A traveling in the same lane as the own vehicle, and b ₁ , b ₂ , b ₃ and b ₄ are trajectory data of the vehicle B traveling in the adjacent lane. The data.

Here, ₁ is an approximate straight line approximated from the locus data of a ₁ , a ₂ , a ₃ , and a ₄ by the method of least squares calculation described in detail later, and l ₂ is b ₁ , b ₂ , b _3, b is an approximate straight line which is approximated from the _fourth track data.

On the other hand, S is a lane discrimination reference area set near the origin, which is the vehicle position, but the approximate straight line ₁ passes through the area S and the approximate straight line l ₂ does not pass through the area S. So in this case,
The vehicle that draws the approximate straight line ₁ (that is, the vehicle A) can be determined to be the vehicle on the same lane as the own vehicle.

In the example of FIG. 5, the lane discrimination reference area S is set in a rectangular shape. However, the vehicle discrimination reference area is provided within a certain range of the azimuth axis θ or the distance axis R centered on the origin, and the approximate straight line is It is also possible to determine that the vehicle when crossing these is on the same lane.

For example, in FIG. 6, the discrimination line S _{0 as} described above on the azimuth axis θ is shown.
An example is shown in which (however, −θa ≦ S ₀ ≦ θa) is set.

Next, the method of calculating the approximate straight line by the method of least squares will be described in detail.

Now, as shown in FIG. 7, r _{1 is} used as the trajectory data of the vehicle ahead.
(Θ ₁ , R ₁ ), r ₂ (θ ₂ , R ₂ ), ... r _n-1 (θ _n-1 , R _n-1 ) r
It is assumed that n pieces of data of n (θn, Rn) are obtained.

Then, assuming that the approximate straight line is approximated by the equation R = a + bθ (1) from these locus data, it is only necessary to obtain the values of a and b below.

By the way, in this case, from the condition of least squares It suffices to find a and b that minimize the value of.

Then, this can be solved for a and b by the following equations (3) and (4).

The above is the calculation method of the approximate straight line using the calculation method of the least squares method.

On the other hand, FIG. 8 shows an example of detection of the trajectory data obtained by the experiment.

The example shown in FIG. 3 is an example in the case where the vehicle is traveling on the right curve road as shown in FIG. 3, and the locus data of the vehicle traveling on the outer lane (travel lane) is lm, Ln the locus data of the vehicle traveling in the inner lane (overtaking lane)
Is shown as.

Here, FIGS. 7A and 7B show the case where the radar vehicle 50 is in the traveling lane, and FIGS. 7C and 7D show the case where the radar vehicle 50 is in the overtaking lane. . In addition, (a),
(C) is a curved road with a radius of curvature of 300 m, and (b) and (d) are curved roads with a radius of curvature of 1000 m.

As is clear from the figure, no matter whether the radar vehicle 50 is traveling in the traveling lane or in the overtaking lane, when a vehicle traveling in the same lane approaches, its trajectory is linear. Yes, and you can see that it is heading toward the origin.

The above is the method for determining the identity between the traveling lane of the front vehicle and the traveling lane of the own vehicle, which is a characteristic part of the present embodiment. Next, referring to the flowchart of FIG. 9, the vehicle according to the present embodiment When a vehicle equipped with a rear-end collision prevention warning device is traveling on a curved road as shown in FIG. 3, only a front vehicle traveling on the same lane as the own vehicle is likely to collide. A processing procedure in the case of traveling while judging as a certain vehicle will be described.

When the program is started, first, the distance Ri to the front vehicle and the azimuth θi of the front vehicle are detected based on the input signals from the distance counting circuit 11 and the scanner drive circuit 2 (step 100), and then the front vehicle is detected. The relative speed V _R between the own vehicle and the preceding vehicle is calculated by differentiating the distance Ri with respect to time (step 110).

Then, the output from the vehicle speed sensor 14 is applied to the own vehicle speed V.
Is detected (step 120).

In this way, when the relative speed V _R with respect to the preceding vehicle and the own vehicle speed V are detected, the speed of the preceding vehicle is detected from these detection results.
Va (however, Va = V−V _R ) is calculated (step 130).

By the way, in this embodiment, the identity of the lane in which the preceding vehicle is traveling and the lane in which the own vehicle is traveling is determined before the warning output determination for preventing the rear-end collision. Therefore, first, at step 140, an approximate straight line of the trajectory data of the vehicle ahead is obtained (step 140).

Then, in step 150, it is determined whether or not this approximate straight line passes through a predetermined lane determination reference area.

Here, if the approximate straight line passes through the lane discrimination reference area (YES in step 150), it is determined that the preceding vehicle is traveling in the same lane as the own vehicle as described above. Will be judged.

Therefore, in the next step 160, the safe inter-vehicle distance As is calculated.

Here, the safe inter-vehicle distance As means a limit distance at which a collision can be avoided even if the front vehicle is suddenly braked and decelerated at a deceleration α or more of the front vehicle.

Then, this safe inter-vehicle distance As is, for example, the vehicle speed V,
Let Va be the vehicle speed of the vehicle ahead, td be the reaction delay time from the recognition of the alarm to stepping on the brake, and α be the deceleration of the vehicle ahead.
It can be shown by the following formula.

As = V · td + (V ² −Va ² ) / 2α (5) With the above processing, when the safe inter-vehicle distance As and the distance Ri to the vehicle ahead are obtained, the collision prevention is performed based on these detection results. Whether or not the alarm of
It is checked whether ≧ Ri (step 170). If an alarm should be issued here (YES in step 170), the alarm means 15 issues an alarm (step 180).

As described above, the device of this embodiment detects a plurality of locus data of the vehicle ahead by transmitting the laser light to the front of the vehicle.

Then, an approximate straight line of the trajectory of the vehicle ahead is obtained from these data by the method of least squares.

Next, it is checked whether or not this straight line passes around the position of the own vehicle, that is, whether or not it passes through a predetermined lane discrimination reference area.

Here, when the approximate straight line passes through the lane discrimination reference area, the vehicle in front is on the same lane as the own vehicle, and it is determined that the vehicle may have a rear-end collision.

Then, in this embodiment, it is determined that only the front vehicle traveling in the same lane as the own vehicle is a vehicle having a possibility of a rear-end collision, and whether or not a warning for preventing a rear-end collision should be issued. It is configured.

Therefore, unlike the conventional device, a false alarm is not given as a vehicle having a possibility of a rear-end collision while traveling in another lane, and an alarm is given only when a vehicle having a possibility of a rear-end collision is detected. It will be.

Further, in this embodiment, since it is possible to detect which of the curved roads the vehicle is currently traveling from and the radius of curvature of the curved roads from the magnitude of the inclination of the approximate straight line,
This makes it possible to provide the driver with useful information for driving.

Next, a second embodiment of the present invention will be described with reference to FIGS.

The same components as those described in the first embodiment will be designated by the same reference numerals.

By the way, the basic configuration of this embodiment is shown in FIG. 10, but this embodiment is different from the first embodiment in that an unconscious state detecting means 16 for detecting the unconscious state of the driver during traveling is added. That is what is being done.

This is because, for example, while the vehicle is traveling on a curved road, when the driver is unconscious due to a drowsiness or the like, the front vehicle that may have a rear-end collision is not limited to a vehicle on the same lane. For example, in FIG. 3, when the driver of the radar vehicle 50 is in an unconscious state, the radar vehicle 50 may go straight as it is, and thus the vehicle B traveling in the adjacent lane is also included as a vehicle having a possibility of a rear-end collision. Be done.

Therefore, when an unconscious state of the driver is detected, it is determined whether or not there is a possibility of a rear-end collision with a vehicle other than the one traveling in the lane of the own vehicle, and an alarm for preventing a rear-end collision is issued if necessary. This is the present embodiment.

The processing procedure of this embodiment will be described below with reference to the flowchart of FIG.

When the program starts, it is first checked whether or not the driver is in an unconscious state because he is dozing or the like (step 200).

Here, as a means for detecting the unconscious state of the driver, there is, for example, a steering sensor system, and the unconscious state of the driver can be detected by detecting a change in steering angle.

Here, if the driver's unconscious state is not detected (NO in step 200), only the vehicle traveling in the same lane as the own vehicle may have a rear-end collision.
The processing of 0'-180 'is performed. The processing procedure of steps 100 'to 180' in this case is the same as step 10 in FIG.
Since it is exactly the same as the processing procedure of 0 to 180, description thereof will be omitted.

On the other hand, when the unconscious state of the driver is detected (YES in step 200), the vehicle having the possibility of a rear-end collision is not limited to the vehicle traveling in the same lane as the own vehicle.

Therefore, in this case, the processing of steps 210 to 280 is performed.

That is, first measure the distance Ri to a detected object (step 210), then by differentiating the value time, and calculates the relative velocity V _R between the host vehicle and the preceding vehicle (step 22
0).

Then, the output from the vehicle speed sensor 14 is applied to the own vehicle speed V.
Is detected (step 230).

In this way, when the relative speed V _R with respect to the vehicle in front and the own vehicle speed V are detected, the speed of the detected object is determined from these detection results.
Va (however, Va = V−V _R ) is calculated (step 130).

Then, in the processing of the next step 250, the safe inter-vehicle distance As
Is calculated (step 250).

If the distance Ri to the vehicle ahead is equal to or less than the safe inter-vehicle distance As (YES in step 260), an alarm for preventing a rear-end collision is output (step 270).

By the way, in this embodiment, the above warning is output until the driver's consciousness is awakened and the brake is depressed (steps 270 and 280), and when the brake is depressed (YES in step 280), the processing of step 200 and thereafter is performed again. Will return to.

The device shown in FIG. 12 is used as a means for detecting whether or not the brake is depressed.

In the figure, a conductor plate 31 is attached to the brake pedal 30. Here, when the brake pedal 30 is depressed in the direction of arrow F to reach the wavy line position, the conductor plate 31 contacts the terminals P and Q, and the terminals P and Q are connected. Therefore, the power supply side V
Microcomputer supplied from _DD through resistor R
The current to the 13 side is suppressed, and the potential of the pin terminal T of the microcomputer 13 drops. As a result, the microcomputer 13 can detect the depression of the brake pedal 30.

In this embodiment, whether or not the brake is stepped on by the device as described above is detected.
Instead of the processing of (1), a method of continuously sounding an alarm for a fixed time (for example, one minute) may be used.

As described above, the second embodiment is provided with the unconscious state detecting means 16 in addition to the configuration of the first embodiment, and when the driver's unconscious state is detected due to the driver's drowsiness during traveling, the same as the own vehicle. In addition to vehicles on the lane, vehicles on other lanes are also added to determine the possibility of a rear-end collision. Therefore, the rear-end collision prevention alarm can be output more accurately than in the device according to the first embodiment.

In the second embodiment, the unconscious state detecting means 16 is provided to detect the unconscious state of the driver and issue an alarm for preventing a rear-end collision. However, the unconscious state detecting means 16 is used instead of the driver. It is also possible to provide a means for estimating the degree of fatigue and issue a warning for preventing a rear-end collision by estimating the degree of fatigue of the driver based on the distance traveled by the driver, the driving time, and the like.

Next, a third embodiment of the present invention will be described with reference to FIGS. 13 and 14.

The same components as those described in the first embodiment will be designated by the same reference numerals.

By the way, FIG. 13 shows the basic configuration of this embodiment, but this embodiment differs from the first embodiment in that a rain fog detecting means 17 for detecting rain, fog, etc. is added. It is that you are.

This is not limited to a vehicle traveling in the same lane as the own vehicle, in the case where the visibility in front of the vehicle is poor due to rain or fog, and there is a possibility of a rear-end collision. For example, in FIG. 3, when the visibility of the radar vehicle 50 is poor due to rain or fog, the vehicle B that is traveling in the adjacent lane is also included as a vehicle that may collide.

Therefore, if rain or fog is detected, it is determined whether there is a possibility of a rear-end collision with a vehicle other than the one traveling in the lane of the vehicle,
In this embodiment, an alarm for preventing a rear-end collision is issued if necessary.

The processing procedure of this embodiment will be described below with reference to the flowchart of FIG.

When the program starts, it is first checked by the output of the rain / fog sensor 17 whether it is raining or there is fog (step 300).

The rain fog sensor 17 includes (1) one that uses ON / OFF information of the wiper, (2) one that uses ON / OFF information of the fog lamp and headlight, and (3) a raindrop sensing wiper sensor. (4) A laser radar raindrop sensor, (5) A laser radar reflected signal, and so on.

Here, if the surrounding weather conditions are good and there is no rain or fog (NO in step 300), the processing of steps 100 ′ to 180 ′ is performed, and only vehicles on the own lane may collide. As a vehicle, processing for preventing a rear-end collision will be performed.

Note that the processing of steps 100 'to 180' is exactly the same as the processing of steps 100 to 180 in the first embodiment, so a description thereof will be omitted.

On the other hand, when the rain / fog sensor 17 determines that the surrounding weather condition is rain or fog (YES in step 300), step 21
The processing below 0'is performed to determine whether there is a possibility of a rear-end collision targeting a vehicle traveling in a lane different from the lane in which the vehicle is traveling, and if necessary, an alarm to prevent a rear-end collision is issued. Will be issued.

In this case, the processing procedure of steps 210 ′ to 240 ′ is
Since the processing procedure of steps 210 to 240 in the second embodiment is exactly the same, description thereof will be omitted.

In the third embodiment, as described above, the rain / fog sensor 17 is provided in addition to the structure of the first embodiment, and when the surrounding weather conditions are bad and the vehicle is in a rainy or foggy condition, the vehicle is in the same lane as the own vehicle. Not only that, vehicles on different lanes are also included in the target of the rear-end collision possibility judgment.

Therefore, it is possible to output a more accurate rear-end collision prevention alarm as compared with the device of the first embodiment.

In the third embodiment, the rain / fog sensor 17 is provided to detect whether or not the visibility of the surroundings is good and to issue an alarm for preventing a rear-end collision. It is also possible to provide a sensor for detecting the degree and perform similar control.

<< Advantages of the Invention >> As described above, the vehicle rear-end collision warning device according to the present invention is based on the distance data to the preceding vehicle and the azimuth data of the preceding vehicle. And the approximate straight line of the traveling locus of the front vehicle is calculated based on the plural locus data, and when the approximate straight line passes near the origin on the above coordinates, the front vehicle is on the same traveling lane as the own vehicle. Since it is configured to determine that the vehicle is traveling, there is an effect such that an accurate rear-end collision warning can be issued by setting only a forward vehicle on the same lane as the own vehicle as a target vehicle having a rear-end collision possibility.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention, FIG. 2 is a block diagram showing the basic configuration of the first embodiment to which the present invention is applied, and FIG. 3 is a rear-end collision possible when a radar vehicle is traveling on a curved road. FIG. 4 is a diagram for explaining a traveling locus of a forward vehicle when traveling on a curved road, FIG. 5 is an action diagram for detecting a forward vehicle on the same lane as the own vehicle, and FIG. 6 is a lane. FIG. 7 is an explanatory view when the discrimination reference area is set on the azimuth axis θ, FIG. 7 is an explanatory view when an approximate straight line is obtained by a calculation method of the least square method, and FIG. FIG. 10 is a flow chart showing a processing procedure of the first embodiment, FIG. 10 is a block diagram showing a basic configuration of a second embodiment to which the present invention is applied, and FIG. 11 is a processing procedure of the second embodiment. Flowchart shown, FIG. 12 is an explanatory view of a device for detecting depression of the brake pedal, FIG. 13 is a block diagram showing the basic structure of the third embodiment to which the present invention is applied, FIG. 14 is a flow chart showing the processing procedure of the third embodiment, and FIG. 15 is the operation of the rear-end collision warning device in the conventional example. Explanatory drawing, FIG. 16 is an explanatory view of a positional relationship between a radar vehicle and a front target object for explaining the operation principle of the present invention, and FIG. 17 is an explanatory view of a distance calculation action between the radar vehicle and a front object in FIG. is there. 1 ... Scanner 2 ... Scanner drive circuit 3 ... Traveling lens 4 ... Laser diode 5 ... Laser diode drive circuit 6 ... Trigger pulse generation circuit 7 ... Power supply circuit 8 ... Light receiving lens 9 ... Light receiving element 10 ... Amplifier 11 ... Distance counting circuit 12 ... Clock 13 ... Microcomputer 14 ... Vehicle speed sensor 15 ... Warning means 16 ... Unconscious state detection means 17 ... Rain fog sensor 50 ... Radar vehicle

Claims (1)

[Claims] 1. A distance detecting means for detecting a distance between a vehicle and a front vehicle, a safe inter-vehicle distance calculating means for calculating a safe inter-vehicle distance while the vehicle is traveling, and an azimuth detection for detecting an azimuth of a front vehicle with respect to the own vehicle. Means and a trajectory for detecting trajectory data of the forward vehicle on the azimuth / distance coordinate based on the distance data to the forward vehicle detected by the distance detecting means and the azimuth data of the forward vehicle detected by the azimuth detecting means. Data detecting means, an approximate straight line calculating means for calculating an approximate straight line of a plurality of locus data detected by the locus data detecting means at predetermined time intervals, and an approximate straight line calculated by the approximate straight line calculating means are on the coordinates. Lane lane identity determining means for identifying the identity of the lane of travel of the preceding vehicle and the lane of travel of the host vehicle based on whether or not the vehicle passes near the origin. When it is determined by the identity determining means that the traveling lane of the preceding vehicle and the traveling lane of the own vehicle are the same, and the distance to the preceding vehicle detected by the distance detecting means is equal to or less than the safe inter-vehicle distance. A rear-end collision warning device for a vehicle, comprising: an alarm means for issuing an alarm when