JPH08327731A - Method for detecting azimuth by radar, azimuth detecting radar equipment and collision avoidance device for automobile - Google Patents

Abstract

PURPOSE: To realize the radar equipment, which can detect even the azimuth of a target body and the collision warming device for automobiles, which can judge the risk of collision precisely, by a simple constitution. CONSTITUTION: The first radar equipment 11, which has the first antenna pattern, detects the distance to a target body and outputs the received signal level, and the second radar equipment 12, which has the second antenna pattern that is different from the first antenna pattern and wherein a part is overlapped with the first antenna pattern, are provided. The second radar equipment detects the distance to the target body and outputs the received signal level. Furthermore, an azimuth/level-ratio-data memory means 13, which stores the relationship of the ratio of the received signal levels of the second and first antenna patterns with respect to the azimuth measured beforehand, and an azimuth computing means 14, which computes the ratio of the received signal levels and the azimuth of the target body corresponding to the computed ratio of the received signal level in accordance with the relationship stored in the azimuth/level-ratio-data memory means 13, are both provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device used for a vehicle collision warning device and the like, and more particularly to a radar device capable of detecting a direction and a vehicle collision warning device using the radar device.

[0002]

2. Description of the Related Art A radar device detects a radio wave that radiates a radio wave, is reflected by a target object and returns, and detects a time required for a round trip to detect a distance to the target object. Since the radio waves are reflected by all target objects within the radio wave emission range and the reflected radio waves are detected, the direction of the target object cannot be detected. Therefore, when it is also necessary to detect the azimuth of the target object, the emitted radio wave is scanned as a narrow beam (scan), and the presence or absence of the target object at each scanning angle and the distance to the target object are detected. It detected the distance and direction of the object.

Since the resolution of azimuth detection is determined by the size of the radiated radio wave beam, it is necessary to use a narrow beam in order to improve the resolution of azimuth detection, and it is necessary to make the antenna pattern a narrow beam shape. There is. In order to narrow the antenna pattern, it is necessary to increase the size of the antenna, which makes the antenna larger. As the scanning method of the radiated radio wave beam, a mechanical scanning method of mechanically rotating the antenna itself and a method of combining the signal paths of a plurality of antennas forming the array antenna by changing the phase difference using the array antenna are combined. There are electronic scanning methods that change the direction of the antenna pattern. The mechanical scanning method has a problem that the device becomes large and reliability such as durability is not sufficient. The electronic scanning method is highly reliable because it has no moving parts, but it requires the use of a phase shifter according to the number of scanning steps, and it also requires a high-power transmitter because the antenna efficiency decreases. There is a problem of high cost.

[0004]

A vehicle collision warning device has been developed in which a radar device is mounted on an automobile and an obstacle in the traveling direction is detected to warn a driving vehicle when it is determined to be dangerous. ing. Even in a radar device used in a vehicle collision warning device, if not only the distance to a target object ahead but also the direction of the target object can be detected, it is possible to determine whether the target object is on a traveling route such as a traveling lane of the own vehicle. It is desirable to be able to detect the azimuth of the target object because it can be performed accurately.

When a radar device having a mechanical scanning mechanism is used in a collision warning device for an automobile, it is difficult to provide a large mechanical scanning mechanism because the mounting space is small, and the durability is also large due to vibrations caused by traveling. It becomes a problem. Furthermore,
When traveling at a speed of about 100 km / h, several tens of
It is necessary to be able to detect obstacles in front of m, and a scanning speed of several tens of cycles / s is required for safe traveling, and it is quite necessary to realize such a scanning speed with a mechanical scanning mechanism. Difficult and expensive equipment.

When a radar device for electronically scanning a collision warning device for a vehicle is used, there is a problem that the cost is high because of the large number of phase shifters and the high-power transmitters. Therefore, the conventional vehicle collision warning device uses a radar device having a relatively narrow fixed antenna pattern. FIG. 9 is a diagram showing an example of an antenna pattern of a radar device used in a conventional vehicle collision warning device.

In FIG. 9, reference numeral 900 is a road, 901 is an automobile equipped with a radar device, and 91 is a vehicle.
0 is the detection range determined by the antenna pattern, and 9
50 is an obstacle on the roadside, and 960 is an obstacle at a close position on the road. The detection range 910 is, for example,
The lane width of the expressway is determined to be slightly wider than the lane width at a position 100 m ahead. Therefore, when driving on a road with a narrower lane width than a normal highway,
As shown in, the obstacle 95 on the road
There is a problem that when 0 is detected, an alarm is frequently generated and the driver is annoyed. In order to prevent such a problem, it is conceivable to narrow the detection range, but this makes it impossible to sufficiently fulfill the original function of the collision warning device.

Further, the detection range as shown in FIG.
Although it is almost equal to the traveling route at the position of 0 m, the detection range becomes narrower at the position closer than that, and there is a problem that the obstacle 960 at the near position on the road shown in FIG. 9 cannot be detected. The vehicle has reached this position by traveling, and if the obstacle 960 is a stationary object, it will be detected at the previous stage and an alarm will be issued at that stage, so no particular problem occurs. If an automobile is traveling in the lane adjacent to 960 and enters the traveling lane of its own vehicle in a state as shown in FIG. 9 which is close to the own vehicle, a warning is issued even though it is dangerous. There is a problem that is not done. In order to solve such a problem, when the antenna pattern is widened to widen the detection range, there is a problem that an obstacle on the road side is detected and an alarm is frequently issued.

The present invention has been made in view of the above problems, and realizes a radar device capable of detecting a bearing with a simple structure, and at the same time, using such a radar device, an obstacle in the traveling route of the vehicle. An object of the present invention is to realize a collision warning device for an automobile that reliably detects only an object and issues an alarm.

[0010]

FIG. 1 is a diagram showing the basic construction of an azimuth detecting radar device according to the present invention. As shown in FIG. 1, the azimuth detecting radar device of the present invention has a first antenna pattern, and a first radar device 11 that detects a distance to a target object and outputs a reception level, and an antenna pattern A second radar device 12 that has a second antenna pattern that is different from the first antenna pattern and partly overlaps the first antenna pattern, detects the distance to the target object, and outputs the reception level; Azimuth / level ratio data storage unit 13 that stores the relationship between the ratios of the reception levels of the second antenna pattern and the first antenna pattern with respect to the previously measured azimuth, and the reception of the second antenna pattern and the first antenna pattern. The level ratio is calculated and calculated according to the relationship between the direction and the reception level ratio stored in the direction / level ratio data storage means 13. Characterized in that it comprises a bearing calculation unit 14 for calculating the azimuth of the target object corresponding to the ratio of the level.

The first radar device 11 and the second radar device 12 can be constructed by array antennas whose phase difference between signal paths can be switched. The first antenna pattern and the second antenna pattern are realized by switching the phase difference between the signal paths of the array antenna. The collision warning device for a vehicle according to the present invention can detect the target object from the direction detection radar device that can detect the direction in addition to the distance to the target object and the distance and the direction to the target object output from the direction detection radar device. A vehicle lane obstacle judging means for judging whether the obstacle is in the traveling path of the vehicle, and a safety judging whether there is a risk of collision only for the target object judged as the obstacle in the traveling path of the own vehicle. The present invention is characterized by including a determination unit and an alarm unit that issues an alarm when it is determined that a target object at risk of collision exists.

A collision warning device for an automobile according to another aspect of the present invention comprises a radar device, and safety judging means for judging whether or not there is a risk of collision with the target object from the distance to the target object output from the radar device. In a collision warning device for an automobile, which comprises a warning device that issues a warning when the safety judgment device judges that the target object is a risk of collision, the radar device switches the phase difference of the signal path so that An array antenna switchable so as to have a first antenna pattern having a narrow spread and a second antenna pattern spreading on both sides of the first antenna pattern, and the first and second antennas. At any time, the safety determining means switches the array antenna to have a second antenna pattern. And the time, and judging whether there is a risk of only collision for further predetermined following target object distances short distance from the safe distance.

[0013]

The principle of detection of the azimuth detecting method and the azimuth detecting device according to the present invention will be described. According to the well-known radar equation, the received power Pr is Pt, the radar transmission power is Pt, the antenna gain is G, the cross-sectional area of the target object is δ, the propagation loss is L, and the distance between the radar device and the target object is R. Then, the equation (1) is established between them.

[0014]

[Equation 1]

The antenna gain G is determined for each radar device from the shape of the antenna and the like, and changes depending on the direction θ. Now, the transmission powers Pt of the first radar device 11 and the second radar device 12 are equal, and the antenna gain of the first radar device 11 is G _S (θ) and the antenna gain of the second radar device 12 is G _R (Θ), the first radar device 11 and the second radar device
Let Pr (S) and Pr (R) be the received powers when the radar device 12 of FIG.
r (S) and Pr (R) are represented by equations (2) and (3).

[0016]

[Equation 2]

Therefore, the ratio Pr (P) of Pr (R) and Pr (S)
(R) / Pr (S) is represented by Formula (4).

[0018]

(Equation 3)

Therefore, when the same target object is detected, the ratio of the received powers of the first radar device 11 and the second radar device 12 is determined by the antenna gain of the first radar device 11 being G _S (θ ) And the antenna gain of the second radar device 12 by G
It can be seen that it is determined by the ratio of _R (θ). If it is within a predetermined range, the ratio of antenna gain to azimuth θ G _R (θ) /
Since G _S (θ) is determined, the azimuth θ is calculated from the ratio of received power.
Will be decided. Antenna gain G as above
Is determined for each radar device and is constant, so the ratio of the received powers of the first radar device 11 and the second radar device 12 is measured in advance as a function of the azimuth and stored in the azimuth / level ratio data storage means 13. If the azimuth calculation means 14 calculates the ratio of the reception levels of the second antenna pattern and the first antenna pattern, the azimuth of the target object corresponding to the ratio of the reception levels can be calculated.

For example, the antenna of the first radar device 11
Gain G_S(Θ) and the antenna efficiency of the second radar device 12
The profit is G_R(Θ) is as shown in (1) of FIG. 2 with respect to θ.
It has changed to. Antenna gain ratio G in that case
_R(Θ) / G_S(Θ) changes as shown in (2) of FIG.
It From this, the ratio of antenna gain G_R(Θ) / G
_SAlthough it is not possible to determine whether (θ) is positive or negative,
G depending on the direction θ_R(Θ) / G_S(Θ) is determined
I understand. Therefore, from the ratio of the reception level, G_R(Θ) /
G _SIf (θ) is determined, the one that is symmetric with respect to the center direction
The position θ can be calculated.

The first radar device 11 and the second radar device 12 can be realized by disposing separate radar devices in close proximity, but if an array antenna composed of two adjacent antennas is used. Easy to implement. In the array antenna, when the phase difference between the signal paths of the two antennas is in phase, the antenna gain has an antenna gain such as G _S (θ) in (1) of FIG. 2 and the phase difference between the signal paths of the two antennas is opposite. Then, the antenna has an antenna gain like G _R (θ) in (1) of FIG. Therefore, only by switching the signal path to one antenna between the same phase and the opposite phase, the directions are different and a part of the patterns are overlapped, and the ratio of the antenna gain to the azimuth θ G _R (θ) / Two antenna patterns in which G _S (θ) is uniquely determined can be easily generated.

In the automobile collision warning device of the present invention using the radar device capable of detecting the above-mentioned direction, the direction of the target object can be detected, so that the obstacle can be determined more accurately. The radar device used for a vehicle collision warning device is attached with the radar device based on the center direction of the vehicle body, and the risk of collision is determined assuming that the vehicle is traveling in the center of the driving lane. Even if it cannot be determined whether there is an object, it is possible to determine whether the target object is in the traveling lane.

In a vehicle collision warning system according to another aspect of the present invention, the array is composed of the two adjacent antennas, and the signal path to one antenna is switched between in-phase and anti-phase. By using the antenna at any time, the antenna pattern corresponding to the traveling lane of the own vehicle when in the same phase and the wide-angle antenna pattern when in the opposite phase are used so that the obstacle 960 near the road in FIG. I am able to detect. Moreover, in the case of a wide-angle antenna pattern, it is determined whether or not there is a risk of collision only with respect to a target object that is a shorter distance than the safe distance and is equal to or shorter than a predetermined distance, so there is no risk of detecting an obstacle outside the traveling lane.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An azimuth detecting radar device according to a first embodiment of the present invention has the basic configuration shown in FIG. The configuration shown in FIG. 1 is actually realized by the configuration shown in FIG. In FIG. 3, reference numeral 20 indicates the first and second radar devices 1 of FIG.
Reference numeral 1 is a radar device corresponding to 12 and reference numeral 30 is a computer corresponding to the azimuth / level ratio data table 13 and the azimuth calculating means 14. The computer 30 has a CPU 3
1, ROM 32, RAM 33, I / O port 34
And a bus 35, and an azimuth / level ratio data table 1
3 is stored in the ROM 32 or the RAM 33, and the azimuth calculation means 14 is realized by a program.

As shown in FIG. 3, the radar device 20 includes a transmitter 21 and two antennas 2 constituting a transmitting antenna.
2 and 23, a switch 24 that switches a signal path from the transmitter 21 to the antenna 23, a receiver 26, two antennas 27 and 28 that form a receiving antenna, and a signal path from the antenna 28 to the receiver 26. And a switch 24 for switching. The transmitter 21 and the receiver 26 are used in the conventional radar device, and therefore the description thereof is omitted here.

The two antennas 22 and 23 form an array antenna for transmission, and the two antennas 27 and 28 are
An array antenna for reception is formed. The transmitting array antenna and the receiving array antenna have the same shape. In FIG. 3, an array antenna for transmission and an array antenna for reception are separately provided, but the same array antenna can be switched and used.

A transmission signal is sent from the transmitter 21 to the transmitting array antenna and is radiated. The signal path from the transmitter 21 to the antenna 23 is switched by the changeover switch 24. When the changeover switch 24 is connected to one side, the difference between the length of the signal path from the transmitter 21 to the antenna 23 and the length of the signal path from the transmitter 21 to the antenna 22 depends on the high frequency signal of the radar in the signal path. When it is an even multiple of a half wavelength and the changeover switch 24 is connected to the other side, the length of the signal path from the transmitter 21 to the antenna 23 and the length of the signal path from the transmitter 21 to the antenna 22 are The difference is an odd multiple of half the wavelength of the radar high frequency signal in the signal path. Therefore, the radio waves radiated from the antennas 22 and 23 have the same phase when the changeover switch 24 is connected to one side and the opposite phase when the changeover switch 24 is connected to the other side. Similarly, antenna 2
The signal path from 8 to the receiver 26 is switched by the changeover switch 29, and the signals received by the antennas 27 and 28 reach the receiver 26 when the changeover switch 29 is connected to one side. The phases are the same, and the phases are opposite when the changeover switch 29 is connected to the other side.

In the transmitting and receiving array antennas as shown in FIG. 3, the antenna patterns are as shown in FIG. 4 depending on whether the signal paths of the two antennas forming the array antenna are in phase or in opposite phase. Changes to. In FIG. 4, the solid line indicates the antenna gain G _S (θ) when in phase,
The broken line shows the antenna gain G _R (θ) when the phase is reversed. The divergence angle θ ₀ of the main beam of the antenna pattern in the same phase is determined by the size of the antenna and the frequency of the radio wave. Within the range of ± θ ₀ , it is not possible to determine whether it is positive or negative as in the case shown in FIG. 2, but the ratio of antenna gain to azimuth θ G _R (θ) / G _S (θ ) Is determined. Since the antenna gains G _S (θ) and G _R (θ) in the in-phase and in the anti-phase are determined by the shape of the antenna and the frequency of the radio wave, they are measured at the time when the shape of the antenna and the frequency of the radio wave are determined. There will be no change if done. Therefore, the ratio of antenna gain G _R (θ) / G _S (θ) to the direction θ is measured in advance and stored in the ROM 32 as a table. here,
A function for calculating the azimuth θ with respect to the antenna gain ratio G _R (θ) / G _S (θ) may be determined and stored in the ROM 32.

The azimuth calculation program stored in the computer 30 cyclically switches the changeover switches 24 and 29 simultaneously through the I / O port 34.
Then, the ratio of the levels of the received signals at the same phase and the opposite phase output from the receiver 26 is calculated, and the square root thereof is calculated to calculate G _R (θ) / G _S (θ) of the target object, and the ROM 32 The azimuth θ of the target object is calculated from the table or function stored in.

Next, an embodiment of an automobile collision warning device using the azimuth detecting radar device of the first embodiment will be described. FIG. 5 is a block diagram of a vehicle collision warning system according to the second embodiment. In FIG. 5, reference numeral 41 is an azimuth detection radar device capable of azimuth detection as shown in the first embodiment, and 42 is a target object according to the distance and azimuth to the target object output from the azimuth detection radar device 41. Reference numeral 43 is a vehicle lane obstacle determining means for determining whether the vehicle is in a lane which is a traveling route of the vehicle, and 43 determines whether there is a risk of collision based on the distance to the target object output from the azimuth detecting radar device 41. Is a safety judgment means having the same function as the conventional one,
Reference numeral 44 is an alarm means for issuing an alarm and notifying the driver when the safety determining means 43 determines that the target object is a risk of collision. The safety determination means 43 of the present embodiment has the same function as that of the conventional vehicle collision warning device, but only the target object which the own vehicle lane obstacle determination means 42 has determined to be an obstacle in the own vehicle lane is collided. The difference is that it determines whether there is a danger of.

FIG. 6 shows the vehicle lane obstacle judging means 4 described above.
2 is a diagram illustrating a method of determining whether the target object is an obstacle in the vehicle lane, (1) is a diagram illustrating a target example of the determination method described here, and (2) is a diagram. It is a figure which shows the range determined with the obstacle of a own vehicle lane with respect to a distance and a direction. In (1) of FIG. 6, reference numeral 51 is a vehicle equipped with the vehicle collision warning system of the second embodiment, 52 and 53 are vehicles traveling in front of the vehicle 51, and the vehicle 52 is an adjacent vehicle. The vehicle 53 is traveling in the lane, and the automobile 53 is traveling in the same lane as the automobile 51.
When the car 51 to the car 52 are captured by the radar device,
Distance R in the direction of angle θ1 with respect to the traveling direction of the automobile 51
It is in position 1. Similarly, the automobile 53 is located at a distance R2 in the traveling direction of the automobile 51.

Assuming that the width of the traveling lane is D and the vehicle equipped with the radar device is traveling in the center of the lane, the distance R from the vehicle equipped with the radar device to the desired boundary position with the adjacent lane and the traveling direction. On the other hand, the angle θ is expressed by the equation (5). D = 2R sin θ (5) As shown in (2) of FIG. 6, when the distance R is represented by the horizontal axis and the azimuth θ is represented by the vertical axis, the position of the boundary with the adjacent lane represented by the equation (5). Is represented by a solid line. The area below the line is the range of the vehicle lane, and the target position whose coordinate position indicated by the distance and direction is below the line is a target for determining whether there is a risk of collision. The automobiles 52 and 53 shown in (1) of FIG. 6 are located at the positions shown in (2) of FIG. 6, respectively, and since the automobile 52 is outside the range of the own vehicle lane, it is excluded from the determination target. Since it is within the range of the own vehicle lane, it is a target of determination, and similarly to the conventional case, the safety determination means 43 determines whether there is a risk of collision based on the traveling speed of the automobile 51 and the distance R2.

FIG. 7 is a flow chart showing the judgment operation in the second embodiment. Steps 700 to 705 correspond to the operation of detecting the azimuth of the target object by the radar device of the first embodiment. In step 700, the changeover switches 24 and 29 of FIG.
Ensure that the signal paths to 3, 27 and 28 are in phase.
In step 701, the distance to the target object and the reception level are measured. In step 702, the switches 24 and 29 are switched to make the signal path to the antenna antiphase, and in step 703, the distance to the target object and the reception level are measured. In step 704, the ratio of the reception level in the in-phase and the reception level in the same phase are calculated, and in step 705, the direction of the target object corresponding to the ratio of the reception levels is detected.

In step 706, the own vehicle lane obstacle judging means 42 judges whether the target object is an obstacle in the own vehicle lane as described in FIG. If it is not an obstacle in the own vehicle lane, it is not necessary to judge the risk of collision, and the process returns to step 700. If it is an obstacle in the own vehicle lane, in step 707 it is calculated whether there is a risk of collision based on the traveling speed of the own vehicle, the distance to the target object, etc., and step 7
At 08, it is determined whether an alarm needs to be issued according to the calculation result. When it is necessary to generate an alarm, an alarm is generated in step 709 and the process returns to step 700. When it is not necessary to generate an alarm, step 700 is directly performed.
Return to

The third embodiment is a collision warning system for a vehicle which is capable of detecting an obstacle at a short distance by using the radar system having the array antenna used in the first embodiment. The collision warning system for an automobile of the third embodiment has the same structure as the conventional collision warning system for automobiles except that it has the radar device 20 having the array antenna shown in FIG. That is, a normal radar device that includes a radar device, a safety determination device, and an alarm device except for the vehicle lane obstacle determination device 42 of FIG. 5, and the radar device has an array antenna, but does not need to be able to detect the direction. is there. Since these have the same configuration as that of the vehicle collision warning device, description thereof will be omitted, and only different points will be described.

FIG. 8 is a diagram for explaining the detection method of the vehicle collision warning system according to the third embodiment. In the vehicle collision warning system of the third embodiment, the antenna pattern can be switched as shown in FIG. 8 by switching the signal path. In FIG. 8, reference numeral 800 is a road, 801 is a vehicle equipped with the vehicle collision warning device of the third embodiment, 810 is an antenna pattern when the array antenna is switched to the same phase, and 820 is a reverse phase. Is an antenna pattern at the time of switching, and 830 indicates a detection range limit distance at the time of switching to the opposite phase.

As described with reference to FIG. 9, the antenna pattern 810 cannot detect an obstacle in a short distance range even within the own vehicle lane. With the wide-angle antenna pattern 820, such obstacles can be detected, but since obstacles on the roadside are also detected, an alarm is frequently issued although it is not dangerous. In the vehicle collision warning system of the third embodiment, in order to solve such a problem, the antenna pattern is periodically switched to the antenna patterns 810 and 820 to detect the target object. Then, in the detection by the antenna pattern 820, a target object having a distance equal to or longer than the limit distance indicated by 830 is excluded from the determination of the risk of collision.
As a result, the detection range can be expanded without frequent alarms even though it is not dangerous, and it is possible to more accurately determine whether or not it is safe.

[0038]

As described above, according to the present invention,
A radar device that can detect the azimuth of a target object with a simple configuration is realized, and a small azimuth-detectable radar device becomes possible. It becomes possible to determine the risk of collision.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of an azimuth detecting radar device of the present invention.

FIG. 2 is a diagram for explaining the principle of the azimuth detecting radar device of the present invention.

FIG. 3 is a diagram showing a configuration of an azimuth detecting radar device according to a first embodiment.

FIG. 4 is a diagram showing an antenna pattern of the first embodiment.

FIG. 5 is a block diagram of a vehicle collision warning device according to a second embodiment.

FIG. 6 is a diagram illustrating a safety determination method according to a second embodiment.

FIG. 7 is a flow chart showing a determination operation in the second embodiment.

FIG. 8 is a diagram showing a detection method in the third embodiment.

FIG. 9 is a diagram showing a detection range of a conventional automotive radar device.

[Explanation of symbols]

 11 ... 1st radar apparatus 12 ... 1st radar apparatus 13 ... Direction / level ratio data storage means 14 ... Direction calculation means

Claims (5)

[Claims] 1. A azimuth detection method by a radar for detecting a distance to a target object and a azimuth of the target object by a radar device, the method comprising: detecting a distance to the target object and a reception level with a first antenna pattern. A step of detecting a distance to a target object and a reception level with a second antenna pattern having an antenna pattern different from that of the first antenna pattern and partly overlapping the first antenna pattern; Calculated according to the step of calculating the ratio of the reception levels of the antenna pattern and the first antenna pattern, and the ratio of the ratio of the reception levels of the second antenna pattern and the first antenna pattern to the azimuth measured in advance. Calculating the direction of the target object from the ratio of the reception levels Way out. 2. A first radar device (11) having a first antenna pattern, which detects a distance to a target object and outputs a reception level; and an antenna pattern different from the first antenna pattern. A second radar device (1) that has a second antenna pattern, a part of which overlaps the first antenna pattern, detects a distance to a target object and outputs a reception level
2), an azimuth / level ratio data storage means (13) for storing a relationship of a ratio of reception levels of the second antenna pattern and the first antenna pattern to a previously measured azimuth, and the second antenna The ratio of the reception level by the pattern and the first antenna pattern is calculated, and the calculated ratio of the reception level is corresponded according to the relationship between the direction and the ratio of the reception level stored in the direction / level ratio data storage means (13). And an azimuth calculating means (14) for calculating the azimuth of the target object. 3. The first radar device (11) and the second radar device (12) are composed of array antennas (22, 23, 27, 28) capable of switching the phase difference between signal paths, The azimuth detecting radar device according to claim 2, wherein the first antenna pattern and the second antenna pattern are realized by switching a phase difference of a signal path of the array antenna. 4. The target object travels according to the azimuth detecting radar apparatus according to claim 2 or 3 and the distance and azimuth to the target object output from the azimuth detecting radar apparatus (41). Own vehicle lane obstacle judging means (42) for judging whether or not it is an obstacle in the route
And a safety determination means (43) for determining whether there is a risk of collision only with respect to a target object that the own vehicle lane obstacle determination means (42) has determined as an obstacle in the travel route of the own vehicle, and the safety determination Alarm means (4) for issuing an alarm when the means (43) determines that there is a target object at risk of collision
4) A collision warning device for an automobile, comprising: 5. A safety device (43) for determining whether there is a risk of collision with a target object based on a radar device, a distance to the target object output from the radar device, and the safety determination device (43). Alarm means (44) for issuing an alarm when it is determined that the target object is in danger of collision
In the collision warning device for a vehicle, the radar device switches a phase difference of a signal path to thereby provide a first antenna pattern having a narrow spread in a central direction and a second antenna pattern spread on both sides of the first antenna pattern. Array antenna (22, 23,
27, 28) and is switched at any time so as to have the first and second antenna patterns, and the safety determination means (43) includes the array antenna (2).
2, 23, 27, 28) is switched to have the second antenna pattern, it is possible to determine whether there is a risk of collision only for a target object that is a predetermined distance or shorter than the safe distance. A collision warning device for automobiles.