JPH11271441A - On-vehicle radar apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an on-vehicle radar apparatus by which the kind of a preceding vehicle observed by using transmitted and received radio waves can be discriminated, by a method wherein the intensity distribution of reflected radio waves with reference to the scanning angle of a radio-wave beam stored on a memory is compared with a model pattern. SOLUTION: A control circuit 10 continuously outputs radio waves from a high frequency oscillator 20. Radiated radio waves from an antenna 23 are reflected by a mirror 5 which is scanned in a prescribed angle range so as to radiate a preceding vehicle. Its reflected radio waves are received by the antenna 23. A mixer 26 generates a beat signal on the basis of the phase difference between input radio waves from a directional coupler 24 and reflected radio waves from a circulator 25. A frequency analyzer 28 analyzes a frequency. A computing means 11 measures a frequency distribution and received electric power on the basis of its output. On the other hand, the intensity distribution of the reflected radio waves with reference to the scanning angle of received reflected radio waves is stored in a memory 12. A curve shape which is indicated by the stored intensity distribution of the reflected radio waves is compared with a model pattern 13 for every vehicle kind by a vehicle-kind specifying means 14. Whether the vehicle kind of a preceiving vehicle is a bus, a truck or a two-wheeled vehicle is judged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to an improvement of a radar device for observing an inter-vehicle distance to a preceding vehicle traveling on a road. The present invention relates to a technology for identifying a type of a preceding vehicle by a radar device.

[0002]

2. Description of the Related Art Radar devices for mounting on automobiles are becoming widespread. A radar device mounted on an automobile emits a radio wave beam forward in the traveling direction, receives the reflected wave from the preceding vehicle by the radio beam, and measures the time from the emission of the radio wave to the reception of the reflected wave , To observe the inter-vehicle distance to the preceding vehicle. The radio wave allocation for this differs from country to country, but generally 50 to 100G
Hz. Currently popular devices are:
Frequency modulation is performed on the radiated radio wave, frequency detection of the received radio wave is performed, a beat frequency between the detection output and the modulation input of the radiated radio wave is created, and the distance is identified based on the beat frequency.

[0003] The applicant of the present application has disclosed, in Japanese Patent Application No. 8-233416 (not disclosed at the time of filing of the present application), an invention on a structure for mounting a radar device on an automobile and a protective member thereof. Further, Japanese Patent Application No. 9-349299 (not disclosed at the time of filing the present application) disclosed an embodiment corresponding to the form of a display device of a driver's seat and a change in weather.

[0004]

FIG. 5 shows a form for displaying output information of a vehicle radar device in a driver's seat. The basic structure is described in the above-mentioned prior application (Japanese Patent Application No. 9-349299).
No.). That is, a form in which the road surface is displayed on the image display device provided in the driver's seat and the image of the preceding vehicle is displayed as an icon on the road surface is a display that is easy for the driver to understand. In the prior art, it was necessary for the driver to input by operation whether this was a truck, a passenger car, a two-wheeled vehicle, or a bus.

SUMMARY OF THE INVENTION The present invention has been made in view of such a background, and has as its object to provide an apparatus capable of automatically detecting the type of a preceding vehicle from a radio wave received by an on-vehicle radar apparatus. . SUMMARY OF THE INVENTION It is an object of the present invention to provide a device that automatically detects a type of a preceding vehicle and automatically displays the detected type as a different icon on an output screen of a radar device. SUMMARY OF THE INVENTION An object of the present invention is to provide a radar device that does not bother the operation. SUMMARY OF THE INVENTION It is an object of the present invention to provide a radar device that allows a driver to properly recognize a preceding vehicle in heavy fog or driving at night.

[0006]

SUMMARY OF THE INVENTION The present invention is characterized in that the type of a preceding vehicle observed is identified by using a transmission / reception radio wave of a radar device for observing an inter-vehicle distance to the preceding vehicle.

That is, the present invention provides an on-vehicle radar apparatus having means for observing the distance to a preceding vehicle by radiating a radio wave in front of the vehicle and receiving a reflected wave of the radio wave. A means for scanning the angle of the radio beam, a means for storing the intensity distribution of the reflected radio wave with respect to the scanning angle of the radio beam in the memory, and a model pattern in which the intensity distribution of the reflected radio wave with respect to the scanning angle of the radio beam is recorded in advance for each vehicle type And means for comparing the intensity distribution stored in the memory with the model pattern to specify the type of preceding vehicle.

[0008] A plurality of the model patterns are prepared in accordance with the distance to the preceding vehicle, and a display device provided in a driver's seat;
It is desirable to provide a means for displaying an icon corresponding to the type of the preceding vehicle on the screen of the display device.

The radar device emits a radio wave beam forward in the traveling direction, receives a reflected wave of the radio beam from the preceding vehicle, measures the time from the emission of the radio beam to the reception of the reflected wave, and measures the time from the reception of the reflected wave. Observe the inter-vehicle distance to.

When observing the inter-vehicle distance, the angle of a radio wave beam to be radiated and received is scanned, and the intensity distribution of the reflected radio wave with respect to the scan angle of the radio wave beam is stored in a memory.

The intensity distribution stored in the memory is compared with the intensity distribution of the reflected radio wave with respect to the scanning angle of the radio beam previously recorded as a model pattern for a plurality of vehicle types.

The intensity distribution of the reflected radio wave with respect to the scanning angle of the radio wave beam shows a low value at a certain level regardless of the scanning angle in the case of a passenger car. In the case of a track, the scanning angle indicating the right side shows the maximum intensity near 0 degrees, and the intensity decreases as the tails are drawn on both sides. Further, in the case of a bus, a low level is substantially the same as that of a passenger car just behind a scanning angle near 0 °, and a high level is shown on both sides.

As described above, since the intensity distribution of the reflected radio wave differs depending on the vehicle type, this is recorded as a model pattern, and the intensity distribution measured by scanning the angle of the radio beam is compared with the model pattern. The type of the preceding vehicle can be specified.

The distance from the preceding vehicle always fluctuates. If the distance changes even in the same vehicle type, the intensity distribution of the reflected radio wave with respect to the scanning angle of the radio beam also changes. Therefore, the model pattern to be recorded sets multiple distances to the preceding vehicle,
A plurality of patterns corresponding to the distance set for each vehicle type are recorded, and the vehicle type can be specified more accurately by comparing with a model pattern at that distance.

In the case of a vehicle provided with a display device for displaying the road surface in the driver's seat, the vehicle type specified by comparison with the model pattern can be displayed by an icon, so that the preceding vehicle actually seen from the driver's seat Then, the correspondence with the preceding vehicle appearing on the screen of the display device can be correctly recognized. Also, when the front is not visible during heavy fog or night driving, it is possible to properly recognize whether the preceding vehicle is a truck, a passenger car, a motorcycle, or a bus.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

[0017]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a main part of a vehicle-mounted radar device according to an embodiment of the present invention.

The embodiment of the present invention is provided with an on-vehicle radar device 1 for radiating a radio wave in front of a vehicle and observing the distance to a preceding vehicle based on the time until the reflected wave is received. The display device 2 and the image display device 3 are arranged.

The on-vehicle radar device 1 includes a control circuit 10 including a calculating means 11 for calculating a distance to an object in front of the vehicle from a time from transmission of a radio wave to reception of a reflected wave;
A high-frequency oscillator 20 that oscillates a high frequency in an oscillation frequency band of 60 or 76 GHz; an antenna 23 that transmits an output of the high-frequency oscillator 20 as a radio wave beam toward a space in the traveling direction of the vehicle and receives a reflected wave thereof;
The first attenuator 21 and the second attenuator 22 for adjusting the attenuation rate of the radio wave generated by the directional coupler 24, the directional coupler 24 for branching the output from the first attenuator 21, and the output from the directional coupler 24 Circulator 25, which outputs the signal from antenna 23 and receives the reflected wave from antenna 23; mixer 26, which mixes the output of second attenuator 22 and the output of circulator 25; AD
A converter 27, a frequency analyzer 28 that analyzes the frequency of the output of the AD converter 27 and outputs the result to the control circuit 10, and a low-frequency current measuring device 29 that measures the low-frequency current value output from the mixer 26 Be provided.

Further, as a feature of the present invention, the antenna 2
A radio beam angle operating means 4 for scanning the radio beam emitted or received by the radio wave 3 or the angle of any radio beam is provided, and the control circuit 10 stores the intensity distribution of the reflected radio wave with respect to the scanning angle of the radio beam. Memory 12
And a model pattern 13 for recording in advance the intensity distribution of the reflected radio wave with respect to the scanning angle of the radio beam for each vehicle type
And a vehicle type specifying means 14 for comparing the intensity distribution of the radio wave beam stored in the memory 12 with the model pattern 13 to specify the type of the preceding vehicle, and an icon corresponding to the vehicle type specified by the vehicle type specifying means 14 And image processing means 15 for performing image processing of the traveling road and outputting the processed image to image display device 3
And an angle operation control means 16 for controlling the radio beam angle operation means 4.

The radio beam angle operating means 4 includes a mirror 5 for reflecting a radio wave beam to be radiated and received;
The motor 6 scans the angle of the mirror 5 in the range of (−θ to + θ: for example, θ = 10 °) according to a control signal from the angle operation control unit 16.

As shown in FIG. 2, as an example of the vehicle-mounted radar apparatus 1 according to the embodiment of the present invention, the dome 31 which is formed of a dielectric material and emits or receives a radio wave beam, a housing 32, Is housed in the radar apparatus main body formed by the above. The dome 31 and the housing 32 are mechanically coupled by a fixing screw 34 via a packing 33,
A back cover 37 is fixed to a rear end opening of the housing 32 with a mounting screw 36 via a packing 35. The dome 31 is provided with a mounting tool 39 having a mounting hole 38 for mounting to the vehicle body.

The on-vehicle radar device 1 is fixed to a bumper 40 by a fixture 39 as shown in FIG. FIG. 4 shows the mounting positions of the on-vehicle radar device 1, the inter-vehicle distance display device 2, and the image display device 3 in the vehicle body. As shown in FIG. 5, the inter-vehicle distance display device 2 and the image display device 3 are arranged in positions that are easy for the driver to operate and easy to see.

Here, the intensity of the reflected radio wave with respect to the scanning angle of the radio beam will be described. The intensity of the reflected radio wave is represented by a radar reflection cross section (RCS) or a received power (Pr).

The radar reflection cross-sectional area (RCS) is obtained from the following equation: (RCS) = (4πA ² cos ² θ) / λ ² A: Area of Reflected Object θ: Incident Angle of Radio Beam λ: Wavelength of Radio Beam

The received power (Pr) is as follows: (Pr) = Ptg ² λ ² S / (4π) ³ d ⁴ Pt: transmission power g: antenna gain λ: wavelength of radio wave beam S: radar reflection cross section (RCS) D) It is obtained from the distance to the object to be measured.

As shown in FIG. 6, assuming a preceding vehicle on an actual road, in order to obtain the reflected power from the rear of the vehicle, the running direction of the vehicle is set to 0 degree and ± θ ( For example, in the scanning angle range of ± 10 degrees, the inter-vehicle distances d ₁ (30 m), d ₂ (50 m) and d ₃ (100
m), the intensity of the reflected radio wave is measured.
As shown in the figure, the radiation angle is 0 at any distance between vehicles.
Maximum values d ₁ max, d ₂ max and d ₃ m in degrees
ax, and as the radiation angle increases, the intensity of the reflected radio wave decreases with the same tendency in all distribution curves. FIG.
(B) shows the intensity of the reflected radio wave with respect to each inter-vehicle distance.

When such a measurement is performed on vehicles of different vehicle types such as passenger cars, buses, trucks, and motorcycles, the intensity distribution of the reflected radio waves differs depending on the vehicle type. Such intensity distribution characteristics that differ depending on the vehicle type are recorded in the memory 12 in advance as model patterns.

FIGS. 8 (a), (b), (c) and (d)
Shows the intensity distribution of the reflected radio wave with respect to the scanning angle for each vehicle type. This corresponds to a specific inter-vehicle distance d (for example, 50
3 shows the intensity distribution in m). FIG.
Is the intensity distribution of the passenger car. In the case of a passenger car, a substantially constant low radio wave intensity is shown regardless of the scanning angle (θ).
FIG. 3B shows the intensity distribution of the bus. In the case of a bus, the scanning angle is 0 degree, that is, the reflection intensity when a radio wave beam is radiated right behind is as low as a passenger car, and as the scanning angle (θ) increases left and right, the reflection intensity increases. When the scanning angle (θ) is further increased, the reflection intensity tends to be concave. FIG. 4C shows the reflection intensity of the track. In the case of the track, the reflection intensity shows the maximum value when the scanning angle (θ) is 0 degree, and the reflection intensity increases as the scanning angle (θ) increases. It shows a mountain-shaped tendency for the strength to decrease. FIG. 4D shows the reflection intensity of the motorcycle. The reflection intensity shows the maximum value just behind the scanning angle of 0 °, and the reflection intensity rapidly increases when the scanning angle (θ) becomes slightly larger. Shows a tendency to decrease in the shape of a small mountain.

FIG. 9 shows the intensity of the reflected radio wave for each vehicle type with respect to the change in the inter-vehicle distance measured by the on-vehicle radar device according to the embodiment of the present invention. According to this, as the inter-vehicle distance increases, the intensity of the reflected radio wave decreases, the intensity of the reflected radio wave at the same inter-vehicle distance shows the largest value for the bus, and then the intensity of the reflected radio wave decreases in the order of truck, passenger car, motorcycle. .

As described above, the tendency of the intensity distribution of the reflected radio wave with respect to the scanning angle of the radio wave beam and its intensity differ depending on the type of vehicle. Therefore, this tendency of the intensity distribution is recorded as a model pattern for each type of vehicle, and the angle of the radio wave beam is recorded. The type of the preceding vehicle can be specified by comparing the tendency of the intensity distribution during traveling obtained by scanning with the model pattern.

As shown in FIG. 7 and FIG. 9, although the intensity distribution of the reflected radio waves shows the same tendency in the same vehicle type,
Since the intensity level differs depending on the distance between vehicles, a plurality of patterns for the same vehicle type are recorded in the model pattern as shown in FIG. 10 so that the model can be identified even if the distance between vehicles changes.

The example shown in FIG. 10 shows a model pattern of a bus, where the inter-vehicle distances are 30 m, 50 m and 1 m.
The intensity distribution of each reflected radio wave at 00 m is recorded. Similarly, a plurality of model patterns are recorded for passenger cars, trucks, and motorcycles.

The image display device 3 provided in the driver's seat includes
When there is a preceding vehicle, an icon corresponding to the type of the preceding vehicle is displayed. This icon is shown in FIGS. 11A, 11B, and 11C.
13 (a), 13 (b), 13 (c), and 13 (d), the rear shapes of trucks, passenger cars, buses, and motorcycles shown in FIGS.
Is displayed on the image display device 3 as shown in FIG.

Next, the operation of the on-vehicle radar device according to the embodiment of the present invention will be described. FIG. 14 is a flowchart showing a flow of an inter-vehicle distance measuring operation by the on-vehicle radar device according to the embodiment of the present invention.

When the on-vehicle radar device 1 is started, the control circuit 10 continuously outputs radio waves in the 70 GHz band from the high frequency oscillator 20. This radio wave is transmitted to the first attenuator 21
Then, the attenuation rate is adjusted, and radiated from the antenna 23 via the directional coupler 24 and the circulator 25.

The control circuit 10 transmits a control signal from the angle operation control means 16 to the actuator 7 simultaneously with the emission of the radio wave, and drives the electric motor 6 at a predetermined rotation speed. With the rotation of the electric motor 6, the mirror 5 scans in a predetermined angle range (± θ: for example ± 10 degrees). Radio waves radiated from the antenna 23 are reflected by the mirror 5 and radiated to the front of the vehicle.

The radiated radio wave is reflected by a preceding vehicle, further reflected by a mirror 5, received by an antenna 23, and output from a circulator 25 to a mixer 26. Mixer 26
From the directional coupler 24 and the second attenuator 2
A beat signal is generated and output from the phase difference between the radio wave input via the second and the reflected wave from the circulator 25.

The beat signal is converted from an analog signal to a digital signal by the AD converter 27, the gain is adjusted, and the frequency is analyzed by the frequency analyzer 28. The output from the frequency analyzer 28 and the measurement output of the low-frequency current value branched from the mixer 26 and measured by the low-frequency current measuring device 29 are input to the calculating means 11, and the frequency distribution and the reception power thereof are measured. . The distance to the preceding vehicle and the relative speed are calculated from the measured frequency distribution. Next, it is determined whether or not the calculated inter-vehicle distance to the preceding vehicle is smaller than the set inter-vehicle distance alarm limit value. The icon lights red.

On the other hand, the calculating means 11 accumulates the intensity distribution of the received reflected radio wave with respect to the scanning angle in the memory 12, and the vehicle type specifying means 14 calculates the curve shape indicated by the intensity distribution of the stored reflected radio wave and FIG. The vehicle type of the preceding vehicle is compared with the model pattern 13 for each vehicle type described using the passenger vehicle,
It is determined whether the vehicle is a bus, a truck, or a motorcycle.

When the curve shape indicated by the intensity distribution of the reflected radio wave matches any one of the model patterns 13, the received power characteristic of the model pattern is further compared with the received power characteristic of the reflected radio wave to determine whether they match. Is determined. If the received power characteristics match, the vehicle type is specified, and the image processing means 15 displays the specified vehicle type as an icon shown in FIG. 12 on the image display device 3 as shown in FIG.

When the curve shape indicated by the intensity distribution of the reflected radio wave and the model pattern 13 do not correspond to any vehicle type, a black circle mark is displayed. Also, in the comparison of the received power characteristics, when there is no corresponding vehicle type, a black circle mark is displayed. In this case, the size of the black circle changes depending on the intensity of the reflected radio wave. When the radio wave intensity is small, it is small, and when it is large, it is large.

When the driver looks at the preceding vehicle type and wants to display an icon at the position of the black circle mark, the corresponding icon can be selected and displayed by operation.

[0044]

As described above, according to the present invention, the type of the preceding vehicle is automatically detected from the radio wave received by the on-vehicle radar device, and this is automatically displayed as a different icon on the output screen of the radar device. Can be displayed. This allows the driver to recognize the correspondence between the preceding vehicle that is actually seen from the driver's seat and the vehicle displayed on the display screen, and also enables the driver to drive on a road in dense fog or at night when the front is not visible. The driver can properly recognize the type of the preceding vehicle.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of an on-vehicle radar device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an example of the external shape of the vehicle-mounted radar device according to the embodiment of the present invention.

FIG. 3 is a perspective view showing a state where the on-vehicle radar device according to the embodiment of the present invention is mounted on a vehicle body.

FIG. 4 is a diagram showing mounting positions of a vehicle-mounted radar device, an inter-vehicle distance display device, and an image display device according to an embodiment of the present invention.

FIG. 5 is a diagram showing an example of an arrangement of a driver seat of an inter-vehicle distance display device and an image display device according to the on-vehicle radar device according to the embodiment of the present invention.

FIG. 6 is a view for explaining an experimental method of measuring the intensity distribution of a reflected radio wave with respect to the scanning angle of a radio beam by the on-vehicle radar device according to the embodiment of the present invention.

7A is a diagram showing a tendency of the intensity distribution of reflected radio waves at several inter-vehicle distances, and FIG. 7B is a diagram showing the maximum value of the intensity distribution at the inter-vehicle distance.

FIGS. 8A, 8B, 8C, and 8D are diagrams showing the intensity distribution of the reflected radio wave with respect to the scanning angle for each vehicle type according to the embodiment of the present invention.

FIG. 9 is a diagram showing the intensity of reflected radio waves for each vehicle type with respect to a change in the inter-vehicle distance measured by the on-vehicle radar device according to the embodiment of the present invention.

FIG. 10 is a diagram showing an example of a model pattern recorded in the vehicle-mounted radar device according to the embodiment of the present invention.

11 (a), (b), (c) and (d) are diagrams showing the rear shape of each vehicle type.

FIGS. 12A, 12B, 12C, and 12D show examples of representations representing vehicle types.

FIG. 13 is a diagram showing an image display example of the vehicle-mounted radar device according to the embodiment of the present invention.

FIG. 14 is a flowchart showing a flow of an inter-vehicle distance measuring operation by the on-vehicle radar device according to the embodiment of the present invention;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 vehicle-mounted radar device 2 inter-vehicle distance display device 3 image display device 4 radio wave beam angle operation means 5 mirror 6 electric motor 7 actuator 10 control circuit 11 calculation means 12 memory 13 model pattern 14 vehicle type identification means 15 image processing means 16 angle operation control means REFERENCE SIGNS LIST 20 high-frequency oscillator 21 first attenuator 22 second attenuator 23 antenna 24 directional coupler 25 circulator 26 mixer 27 AD converter 28 frequency analyzer 29 low-frequency current measuring instrument 31 dome 32 housing 33, 35 packing 34 fixing screw 36 mounting screw 37 back cover 38 mounting hole 39 mounting tool 40 bumper

Claims (3)

[Claims] 1. An on-vehicle radar device having a means for observing a distance to a preceding vehicle by radiating a radio wave in front of a vehicle and receiving a reflected wave thereof scans an angle of a radio wave beam to be received. Means for storing the intensity distribution of the reflected radio wave with respect to the scanning angle of the radio beam on a memory; a model pattern in which the intensity distribution of the reflected radio wave with respect to the scanning angle of the radio beam for each vehicle type is recorded in advance; Means for comparing the obtained intensity distribution with the model pattern to specify the type of the preceding vehicle. 2. The on-vehicle radar device according to claim 1, wherein a plurality of said model patterns are prepared according to a distance to a preceding vehicle. 3. The on-vehicle radar device according to claim 1, further comprising: a display device provided in a driver's seat; and means for displaying an icon corresponding to the type of the preceding vehicle on a screen of the display device.