JP2003035768A - Radio wave radar device and vehicle loaded therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio wave radar device capable of detecting a state that the axis of a radio wave radar is shifted in the vertical direction to become impossible to accurately catch a preceding vehicle, and a vehicle loaded therewith. SOLUTION: The radio wave radar device has a transmission antenna 210 for emitting radio waves toward a front target, a receiving antenna 202 for receiving the reflected waves from the front target and a signal processing part 208 for detecting the distance, relative speed or the like with the target on the basis of the signal received by the receiving antenna. The signal processing part 208 uses the signal intensity of the reflection signal from the radio wave reflector 6 provided to a part of the vehicle present within the radio wave emitting range of the radio wave radar.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave radar device that emits radio waves, receives reflected waves from a target, and detects a relative velocity and a horizontal direction to the target, and a vehicle equipped with the same. The present invention relates to a radio wave radar device suitable for use in an inter-vehicle distance warning device, an inter-vehicle distance control device and the like, and a vehicle equipped with the same.

[0002]

2. Description of the Related Art A radio wave radar device is used as a distance sensor for an inter-vehicle distance warning device and an inter-vehicle distance control device (ACC: Adaptive Cruise Control). In recent radio wave radar devices, not only the distance to the preceding vehicle and the relative speed,
A scanning method that mechanically shakes the antenna to detect the direction of the preceding vehicle, a beam switch method that switches multiple antennas with different directions in time division, and a monopulse that detects the direction in stereo using two receiving antennas. Various direction detection methods such as a method have been proposed.

On the other hand, in order to maintain desired radar performance, it is widely known that it is important to match the radio wave radiation axis of the radar with the traveling direction of the vehicle. Therefore, for example, JP-A-9-281129 and JP-A-10-1
As disclosed in Japanese Patent No. 32939, there is known one that detects an axis deviation of a radar by a history of a horizontal angle of a target by using an angle detection function of a radio wave radar.

[0004]

However, in the methods described in Japanese Patent Laid-Open Nos. 9-281129 and 10-132939, the radio wave radar has a direction detecting function only in the horizontal direction. No consideration was given to the detection of axial misalignment of the radar. On the other hand, when the radio wave radar is actually used, axial misalignment may occur not only in the horizontal direction but also in the vertical direction due to loosening of the mounting portion due to vibration during a long-term use, light collision, and the like. If this amount of deviation increases, the preceding vehicle does not enter the radio wave irradiation range of the radio wave radar mounted on the vehicle,
The preceding vehicle cannot be detected. As a result, there is a problem that the inter-vehicle distance warning may not operate even if the vehicle approaches the preceding vehicle abnormally, or there may be a dangerous situation where the vehicle approaches the preceding vehicle abnormally during ACC control.

An object of the present invention is to provide a radar device and a vehicle equipped with the radar device, which can detect a preceding vehicle when the axis of the radio wave radar is vertically deviated and the preceding vehicle cannot be correctly captured. To provide.

[0006]

(1) In order to achieve the above object, the present invention provides a transmitting antenna that radiates a radio wave toward a front target and a receiving antenna that receives a reflected wave from the front target. And a signal processing unit that detects the distance to the target, the relative speed, and the like based on the signal received by the receiving antenna, in a radio wave radar device that is within the radio wave emission range of the radio wave radar. The detection means for detecting the axis deviation of the radio wave radar is provided by using the signal intensity of the reflection signal from the radio wave reflector provided in the section. With this configuration, even when the axis of the radio wave radar is displaced in the vertical direction and it becomes impossible to correctly capture the preceding vehicle, this can be detected.

(2) In the above (1), preferably,
The radio wave radar is provided with an actuator that rotates in the vertical direction, and the detection means detects an axis deviation of the radar,
The actuator is driven so as to correct the axis deviation.

(3) Further, in order to achieve the above object,
The present invention is directed to a transmitting antenna that radiates a radio wave toward a front target, a receiving antenna that receives a reflected wave from the front target, and a distance and a relative speed with the target based on a signal received by the receiving antenna. In a vehicle equipped with a radio wave radar device having a signal processing unit for detecting the like, a radio wave reflector provided in a part of the vehicle within the radio wave radiation range of the radio wave radar, and a reflection signal from the radio wave reflector. The detection means is provided for detecting the axis deviation of the radio wave radar by using the signal strength.
With this configuration, even when the axis of the radio wave radar is displaced in the vertical direction and it becomes impossible to correctly capture the preceding vehicle, this can be detected.

(4) In above (3), preferably,
The radio wave radar is of the FMCW type, and the radio wave reflector is fixed to a part of the vehicle.

(5) In the above (3), preferably,
The radio wave radar is a dual frequency CW system, and the radio wave reflector has a relative velocity with respect to the radio wave radar.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The configuration of a radio wave radar device according to a first embodiment of the present invention will be described below with reference to FIGS. First, the overall configuration of the radio wave radar device according to the present embodiment will be described with reference to FIG. Figure 1
1 is a system configuration diagram showing an overall configuration of a radio wave radar device according to a first embodiment of the present invention.

The radio wave radar 2 is mounted on the back surface of the bumper 5 of the vehicle 1. A radio wave reflector 6 is fixed to the bumper 3. The radio wave reflector 6 is arranged in the radio wave irradiation range 3 of the radio wave radar 2, and is fixed so that a part of the radio wave radiated from the radio wave radar 2 hits. The radio wave radar 2 is connected to a driver display 7 and an ACC controller 8 via a communication means such as CAN, and displays information such as the distance to the preceding vehicle detected by the radio wave radar, the relative speed, and the direction of the preceding vehicle. Sent.

FIG. 1A shows a case where the vertical axis of the radio wave radar 2 is normal, and a part of the radio wave emitted from the radio wave radar 2 hits the radio wave reflector 6. On the other hand, as shown in FIG. 1B, when the vertical axis of the radio wave radar 2 faces downward, most of the radio waves emitted from the radio wave radar 2 hit the radio wave reflector 6. On the other hand, FIG.
As shown in (C), when the vertical axis of the radio wave radar 2 faces upward, the radio wave emitted from the radio wave radar 2 does not hit the radio wave reflector 6.

Therefore, by using the reflection signal from the radio wave reflector 6, the radio wave radar 2 determines whether or not the radio wave radar is in an axial misalignment state. When it is determined that the radio wave radar is in the off axis state, the radio wave radar 2 indicates that the radio wave radar is in the off axis state in addition to the distance to the preceding vehicle, the relative speed, the direction of the preceding vehicle, the driver display 7 and the ACC. Notify the controller 8. As a result, the driver and the ACC controller can be prevented from falling into a dangerous driving state based on erroneous information from the off-axis radio radar, and the safety of the system can be improved.

Next, the configuration of the radio wave radar device according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the radio wave radar device according to the first embodiment of the present invention.

The transmitter 210 transmits at a transmission frequency based on the modulated signal 211 from the modulator 209, and the transmitted high frequency signal is radiated from the transmission antenna 201. In a radio wave radar for automobiles, a millimeter wave band radio wave signal is usually used as a high frequency signal.

A radio signal reflected and returned from a target such as a preceding vehicle or an obstacle is received by a receiving antenna 202 and sent to a mixer 204. On the other hand, a part of the output signal of the oscillator 210 is supplied to the mixer 204 through the directional coupler, and the beat signal generated by mixing the signal from this oscillator and the received signal is an analog circuit. Sent to 205. In the case of the homodyne type reception system that directly converts to the baseband, the beat signal output from the mixer 204 becomes the Doppler frequency. The beat signal is converted into a digital signal by the A / D converter 206 and supplied to the FFT (Fast Fourier Transform) unit 207. The FFT unit 207 obtains the frequency spectrum of the beat signal by fast Fourier transform and sends it to the signal processing unit 208.

Next, the principle of radar detection in the radio wave radar device according to the present embodiment will be described with reference to FIG. FIG. 3 is an explanatory diagram of a radar detection principle in the radio wave radar device according to the first embodiment of the present invention. Figure 3
Is an FMCW (Frequency Modulated Continuous Wav
It shows the detection principle of the e) type radar.

In the FMCW system, as shown in FIG. 3 (A), a transmission wave (transmission signal) that is triangularly modulated in the time domain is used.
Is transmitted to the preceding vehicle, and the received wave (received signal) reflected by the preceding vehicle is received.

At this time, a time delay corresponding to the round trip distance of the radio wave to the target and a Doppler shift due to the relative speed occur between the transmission signal and the reception signal, and as shown in FIG. The difference (Doppler frequency) is fb1 in the rising section of the triangular wave and fb2 in the falling section.

For these Doppler signals, the FFT
By performing the (Fast Fourier Transform) process, as shown in FIG. 3C, a target such as a preceding vehicle can be extracted as a signal peak in the frequency domain. At this time, the frequency at which the peak of the target appears is proportional to the distance from the target. That is, the frequency 0 indicates that the distance is 0.

Next, the method of detecting the vertical axis deviation in the radio wave radar device according to the present embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a flowchart showing the details of the vertical axis deviation detection method in the radio wave radar device according to the first embodiment of the present invention, and FIG. 5 is the vertical direction in the radio wave radar device according to the first embodiment of the present invention. It is a principle explanatory view of a direction axis misalignment detection method.

In step s10 of FIG. 4, the signal processing unit 208 of the radio wave radar 2 shown in FIG. 3 performs FFT processing and measures the reflection intensity of the radio wave reflector 6 shown in FIG.

Here, the reflected signal of the radio wave reflector 6 will be described with reference to FIG. FIG. 5 (A) shows FIG.
Similar to the diagram shown in (C), the horizontal axis represents frequency and the vertical axis represents signal strength. Further, the horizontal axis is proportional to the distance to the target, as described above.
Since the radio wave reflector 6 is attached to the bumper 5 of the vehicle 1 as described in FIG. 1, the distance to the target is extremely short, and as shown in FIG. , The peak P1 of the radio wave reflector 6 is detected. Here, since the distance between the radio wave radar 2 and the radio wave reflector 6 is constant, the frequency at which the peak of the radio wave reflector exists is constant regardless of the running state of the vehicle. In FIG. 5A, the peak P2 is, for example, the peak of the preceding vehicle.

Next, in step s20 of FIG. 4, the signal processing section 208 checks whether or not the signal intensity of the radio wave reflector 6 is between the normal levels S1 and S2. Figure 5
As shown in (A), when it is within the normal level range, the process proceeds to step s30, and when it is outside the normal level range, the process proceeds to step s50.

If the level is normal, step s30
At, the signal processing unit 208 determines that the radar axis is in a normal (initial) state, and continues transmission of target information from the radio wave radar 2 to the display 7 and the ACC controller 8 at step s40.

On the other hand, if the signal strength is not between the normal levels S1 and S2 in step s20, the signal processing unit 208 determines that the signal strength from the radio wave reflector 6 is higher than the normal level S1 in step s50. Determine whether or not.

When the axis of the radio wave radar is shifted downward, all the radio wave reflectors 6 are within the radio wave irradiation range 3,
The reflection intensity of the radio wave reflector increases and exceeds S1 as shown in FIG. 6 (B). As a result, the radio wave radar can determine that it is in a downward axis shift state with respect to the initial (normal) state of FIG. Further, when the axis of the radio wave radar is shifted upward, most of the radio wave reflectors are out of the radio wave irradiation range 3, so the reflection intensity of the radio wave reflectors becomes small, and as shown in FIG.
It becomes the following. As a result, the radio wave radar is shown in FIG.
It can be determined that the axis is in an upward misaligned state with respect to the initial (normal) state.

As shown in FIG. 5B, the normal level S1
If it is larger than the normal level S1, it is determined that the axis of the radar is downward in step s60, and if it is not larger than the normal level S1 as shown in FIG. 5C, it is upward in step s70. Judge that there is.

Next, in step s80, the signal processing unit 208 notifies the display unit 7 and the ACC controller 8 that the radar is off-axis.

As described above, when it is determined that the radio wave radar is in the off-axis state, the fact that the radio wave radar is in the off-axis state is added to the driver in addition to the distance to the preceding vehicle, the relative speed, and the direction of the preceding vehicle. It is possible to prevent the driver and the ACC controller from entering into a dangerous driving state based on incorrect information from the radio wave radar whose axis is off, by notifying the display 7 for use in the vehicle and the ACC controller 8 to ensure system safety. Can be increased.

Here, another example of mounting the radio wave radar device according to the present embodiment will be described with reference to FIG. Figure 6
FIG. 6 is a system configuration diagram of another mounting example of the radio wave radar device according to the first embodiment of the present invention. The same reference numerals as those in FIG. 1 denote the same parts. Although illustration of the driver display 7 and the ACC controller 8 is omitted,
It is provided similarly to FIG.

In this example, the radio wave radar 2 is mounted on the back surface of the radiator grill 9 instead of the bumper 5. The radio wave reflector 6 is fixed to a part of the radiator grille 9. FIG. 6A shows a state where the radar axis is normal. On the other hand, FIG. 6B shows the radar axis in the downward state, and FIG. 6C shows the radar axis in the upward state. As a result, the same effect as that of fixing to the bumper portion shown in FIG. 1 can be obtained.

Further, although the example in which only one radio wave reflector 6 is provided is shown, a plurality of radio wave reflectors 6 may be provided. By providing the plurality of radio wave reflectors 6 at different distances from the radio wave radar 2, the peaks of the plurality of radio wave reflectors can be obtained, so that the reliability of the axis deviation detection can be increased. Further, the detection accuracy can be improved by disposing the two radio wave reflectors 6 with their upper and lower positions displaced.

The mounting position of the radio wave reflector 6 is as follows.
It can also be provided on the radio wave transmission cover in front of the radio wave radar.

As described above, when the axis of the radio wave radar shifts in the vertical direction and it becomes impossible to correctly capture the preceding vehicle, this can be detected. Therefore, it is possible to prevent the driver and the ACC controller from falling into a dangerous driving state based on erroneous information from the off-axis radio wave radar, and enhance the safety of the system.

Next, the configuration of the radio wave radar device according to the second embodiment of the present invention will be described with reference to FIGS. 7 and 8. FIG. 7 is a system configuration diagram showing the overall configuration of the radio wave radar device according to the second embodiment of the present invention. Figure 8
6 is a flowchart showing the contents of a vertical axis deviation detection method in a radio wave radar device according to a second embodiment of the present invention. In addition, in FIG. 7, the same reference numerals as those in FIG.
The same part is shown.

In the present embodiment, the radio wave radar 2 shown in FIG. 7A is attached to the bracket 11 via the actuator 10 as shown in FIG. 7B. The actuator 10 can rotate the radio wave radar 2 in the vertical direction by a control signal from the radio wave radar 2.

Next, with reference to FIG. 8, the method of detecting the vertical axis deviation and the axis adjustment method in the radio wave radar device according to the present embodiment will be explained. 8, steps having the same reference numerals as those in FIG. 4 indicate the same processing contents.

In this embodiment, step s65 and step s75 are added, and step s65 shown in FIG.
80 has been deleted.

If it is determined in step s50 that the level is higher than the normal level S1, step s6
At 0, it is determined that the radar axis is downward. Then, in step s65, the signal processing unit 208
The actuator 10 is driven to finely adjust the radar axis of the radio wave radar 2 upward.

On the other hand, if it is determined in step s50 that the level is not higher than the normal level S1, it is determined in step s70 that the radar axis is upward. Then, in step s75, the signal processing unit 208 drives the actuator 10 and finely adjusts the radar axis of the radio radar 2 downward.

After the fine adjustments in steps s65 and s75 are completed, the process returns to step s10, and the radio wave reflector 6
It is possible to return the radar axis to the normal state by measuring the reflection intensity from and repeating the fine adjustment of the radar axis in the vertical direction until it enters between the normal levels S1 and S2.

As described above, according to this embodiment,
When the axis of the radio wave radar is deviated from the initial state, the normal state can be automatically restored.

Next, the configuration of the radio wave radar device according to the third embodiment of the present invention will be described with reference to FIGS. 9 to 11. FIG. 9 is a system configuration diagram showing the overall configuration of the radio wave radar device according to the third embodiment of the present invention. Figure 10
FIG. 9 is an explanatory diagram of a radar detection principle in a radio wave radar device according to a third embodiment of the present invention. FIG. 11 is a principle explanatory diagram of a vertical axis deviation detection method in the radio wave radar device according to the third embodiment of the present invention. Note that FIG.
1, the same reference numerals as those in FIG. 1 indicate the same parts.

In the present embodiment, the radio wave radar 2A shown in FIG. 9 uses a two-frequency CW radio wave radar. The radio wave radar 2A is a radiator grill 9 of the vehicle 1.
Is attached to the back of the. A radio wave reflector 6A is fixed to the radiator grille 9. Radio wave reflector 6A
Uses a speaker whose vibrating part is made of metal.
The radio wave reflector 6A is arranged in the radio wave irradiation range 3 of the radio wave radar 2, and is fixed so that a part of the radio wave radiated from the radio wave radar 2A hits. Radio radar 2A is CAN
Via a communication means such as
It is connected to the C controller 8 and sends information such as the distance to the preceding vehicle detected by the radio wave radar, the relative speed, the direction of the preceding vehicle, and the like.

Next, the detection principle of the dual frequency CW method will be described with reference to FIG.

In the two-frequency CW radio radar 2A, as shown in FIG. 10 (A), the two frequencies f1 and f2 are switched in a time division manner, transmitted to the preceding vehicle and received by the preceding vehicle. Receive the waves. And FIG. 10 (B)
As shown in, the distance to the target is calculated from the phase difference between the two Doppler signals fd1 and fd2 obtained by mixing the transmitted wave and the received wave, and the relative speed to the target is calculated from the Doppler frequency. Further, as shown in FIG. 10 (C), when an FFT (Fast Fourier Transform) process is performed on the Doppler signal, a target such as a preceding vehicle can be extracted as a signal peak in the frequency domain. At this time, the frequency at which the peak of the target appears is proportional to the relative speed with the target. That is, the frequency 0 indicates that the relative speed is 0.

Since the two-frequency CW radar is a radar which detects a target by relative speed, the peak of the target cannot be captured if there is no relative speed between the radar and the target. Therefore, the radio wave radar 2A
Regarding the radio wave reflector 6A for detecting the axis deviation of
Since a peak cannot be captured unless a relative velocity is generated with the radar, a speaker whose vibrating portion is made of metal is used as the radio wave reflector 6A.

Then, as shown in FIG. 11 (A), by vibrating the speaker at a predetermined frequency, the average relative speed of the radio wave reflector is constant, so that the peak P3 of the radio wave reflector is kept at a constant frequency. You can stand at In addition,
The peak P2 is the peak of the preceding vehicle.

FIG. 11A shows the case where the radar axis is in a normal state. At this time, the peak P3 of the radio wave reflector 6A is within the range of normal levels S1 and S2.
FIG. 11B shows the case where the radar axis is in the downward state, and the intensity of the peak P3 of the radio wave reflector 6A is higher than the normal level S1. On the other hand, FIG. 11C shows the case where the radar axis is in the upward state, and the radio wave reflector 6A is shown.
The intensity of the peak P3 is smaller than the normal level S2.

Therefore, as described with reference to FIG. 4, it is detected whether or not the intensity of the peak P3 of the radio wave reflector 6A is between the normal levels S1 and S2, and whether or not the radar axis is in a normal state. Can be determined. Further, as described in FIG. 8, when the radar axis is vertically deviated from the normal state, the actuator shown in FIG. 7 can be provided to automatically adjust the axis.

Although the speaker is used as the radio wave reflector, the electric wave reflector may be a motor having a metallic reflector attached to the rotating part, and the relative distance to the radar antenna may be changed. The same effect can be obtained.

As described above, when the axis of the radio wave radar shifts in the vertical direction and it becomes impossible to correctly capture the preceding vehicle, this can be detected. Therefore, it is possible to prevent the driver and the ACC controller from falling into a dangerous driving state based on erroneous information from the off-axis radio wave radar, and enhance the safety of the system.

[0055]

According to the present invention, when the axis of the radio wave radar deviates in the vertical direction with time and it becomes impossible to correctly catch the preceding vehicle, this can be detected.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing an overall configuration of a radio wave radar device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a radio wave radar device according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a radar detection principle in the radio wave radar device according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing the contents of a vertical axis deviation detection method in the radio wave radar device according to the first embodiment of the present invention.

FIG. 5 is a principle explanatory diagram of a vertical axis misalignment detection method in the radio wave radar device according to the first embodiment of the present invention.

FIG. 6 is a system configuration diagram of another mounting example of the radio wave radar device according to the first embodiment of the present invention.

FIG. 7 is a system configuration diagram showing an overall configuration of a radio wave radar device according to a second embodiment of the present invention.

FIG. 8 is a flowchart showing the contents of a vertical axis deviation detection method in a radio wave radar device according to a second embodiment of the present invention.

FIG. 9 is a system configuration diagram showing an overall configuration of a radio wave radar device according to a third embodiment of the present invention.

FIG. 10 is an explanatory diagram of a radar detection principle in a radio wave radar device according to a third embodiment of the present invention.

FIG. 11 is a principle explanatory diagram of a vertical axis deviation detection method in the radio wave radar device according to the third embodiment of the present invention.

[Explanation of symbols]

1 ... Own vehicle 2, 2A ... Radio wave radar 3… Radio range 4 ... Leading vehicle 5 ... bumper 6, 6A ... Radio wave reflector 7 ... Display 8 ... ACC controller 9 ... Radiator grill 10 ... Actuator 11 ... Bracket

Claims (5)

[Claims] 1. A transmission antenna that radiates a radio wave toward a front target, a reception antenna that receives a reflected wave from the front target, and a distance and relative to the target based on a signal received by the reception antenna. In a radio wave radar device having a signal processing unit for detecting speed, etc., using the signal intensity of a reflection signal from a radio wave reflector provided in a part of the vehicle existing within the radio wave emission range of the radio wave radar, A radio wave radar device comprising a detection means for detecting an axis deviation of the radio wave radar. 2. The radio wave radar device according to claim 1, further comprising an actuator for rotating the radio wave radar in a vertical direction, wherein the detecting means corrects the axis deviation of the radar when the axis deviation is detected. A radio wave radar device characterized by driving an actuator. 3. A transmitting antenna that radiates a radio wave toward a target in front, a receiving antenna that receives a reflected wave from the target in front, and a distance and relative to the target based on a signal received by the receiving antenna. In a vehicle equipped with a radio wave radar device having a signal processing unit for detecting speed, etc., a radio wave reflector provided in a part of the vehicle within the radio wave radiation range of the radio wave radar, and a reflection signal from the radio wave reflector. A vehicle equipped with a radio wave radar device, which is provided with a detection means for detecting an axis deviation of the radio wave radar by using the signal strength of the radio wave radar. 4. A vehicle equipped with the radio wave radar device according to claim 3, wherein the radio wave radar is an FMCW system, and the radio wave reflector is fixed to a part of the vehicle. A vehicle equipped with a radio wave radar device. 5. A vehicle equipped with the radio wave radar device according to claim 3, wherein the radio wave radar is a two-frequency CW system, and the radio wave reflector has a relative velocity with respect to the radio wave radar. A vehicle equipped with a radio radar device.