JP2002303668A - Vehicle object detection device and vehicle following travel control device - Google Patents

Abstract

(57) Abstract: A vehicle object detection device using FM-CW waves can determine the type (shape) of an object. SOLUTION: In a vehicle object detection device using an FM-CW wave, a frequency analysis means 13 generates a detection spectrum based on a beat signal obtained by mixing a transmission wave and a reception wave by a mixer 7, and The object detection means 15 calculates the relative distance and the relative speed of the object from the peak signal obtained by the detection peak determination means 14 based on the detection spectrum. The type determination means 16 determines the type of the object (passenger car or large car) based on the detected spectrum shape, and determines that the determination state has continued for a predetermined time.
When the confirmation is made, the type determination unit 18 determines the type of the object, so that the type (shape) of the object can be determined without using an imaging unit such as a television camera.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object detecting device for a vehicle for detecting an object such as a preceding vehicle by a radar device using an FM-CW wave (frequency modulated continuous wave), and an object detecting device for the vehicle. The present invention relates to a vehicle follow-up running control device using the same.

[0002]

2. Description of the Related Art An object detecting apparatus for a vehicle using an FM-CW wave is known, for example, from Japanese Patent Application Laid-Open No. 11-38129. Japanese Patent Application Laid-Open No. H10-187930 discloses a traveling environment recognition device that enables the type of a preceding vehicle (large vehicle, medium vehicle, small vehicle) to be determined using an imaging device and a radar device.

[0003]

By the way, an object detecting device using a laser beam can detect only a reflector at a rear portion of a vehicle body of a preceding vehicle.
Since the object detection device using W-waves detects the entire body of the preceding vehicle, if the preceding vehicle is a large vehicle, the peak signal is dispersed, and the relative speed of the preceding vehicle obtained by processing the peak signal And the accuracy of the relative distance may be unstable. In order to solve such a problem, it is possible to stabilize the detection accuracy by filtering the peak signal. However, if the target preceding vehicle is a passenger vehicle, unnecessary filtering is performed. As a result, there arises a problem that controllability is deteriorated.

[0004] Further, according to the traveling environment recognition device described in Japanese Patent Application Laid-Open No. 10-187930, it is possible to determine the type of the preceding vehicle, but the structure is required since an imaging device and a radar device are required. There is a problem that it is complicated and costly.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to make it possible to determine the type (shape) of an object in a vehicle object detection device using FM-CW waves.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, an FM-CW wave is transmitted and a reflected wave of the FM-CW wave from an object is received. Transmitting and receiving means, a mixer for mixing a transmitted wave and a received wave to generate a beat signal, a frequency analyzing means for frequency-analyzing the beat signal obtained by the mixer, and an ascending and descending frequency analysis by the frequency analyzing means Among the peak signals obtained based on the result, a detection peak determination unit that determines a peak signal equal to or greater than a threshold value as a detection peak, and an object based on the ascending and descending detection peaks obtained by the detection peak determination unit. An object detection device for calculating at least one of a relative distance and a relative speed with respect to the object, wherein the detection obtained by the frequency analysis by the frequency analysis device is performed. Object detecting apparatus for a vehicle characterized by comprising determining type determination means a type of the object based on the Spectrum shape is proposed.

According to the above configuration, in a vehicle object detection apparatus using an FM-CW wave, a beat signal obtained by mixing a transmission wave and a reception wave with a mixer is subjected to frequency analysis, and a detection result obtained as a result is obtained. Since the type of the object is determined based on the spectrum shape, the type (shape) of the object can be determined without using an imaging device such as a television camera.

According to the invention described in claim 2,
In addition to the configuration of claim 1, a measuring means for measuring a time when the type of the object is determined to be the same by the type determining means, and a type of the object when the time measured by the measuring means is a predetermined value or more. An object detection device for a vehicle, characterized by comprising a type determination means for determining, is proposed.

According to the above configuration, the time when it is determined that the types of the objects are the same is measured, and the type of the object is determined when the time is equal to or longer than a predetermined value. By excluding, the type of the object can be determined accurately.

According to the third aspect of the present invention,
In addition to the configuration of claim 1 or claim 2, the type determination unit determines that the object is a large vehicle when the detected spectrum shape obtained by the frequency analysis unit has a plurality of peaks within a predetermined range. An object detection device for a vehicle is proposed.

According to the above configuration, when the detected spectrum shape obtained by the frequency analysis has a plurality of peaks within a predetermined range, the object is determined to be a large vehicle, so that a large vehicle having a plurality of reflection surfaces is used. It can be determined accurately.

According to the invention described in claim 4,
In addition to the configuration of claim 1 or claim 2, the type determination means determines that the object is a large vehicle when the detected spectrum shape obtained by the frequency analysis means is widely distributed within a predetermined range. An object detection device for a vehicle is proposed.

According to the above configuration, when the detected spectrum shape obtained by the frequency analysis is widely distributed within a predetermined range, the object is determined to be a large vehicle. Can be determined.

According to the invention described in claim 5,
A follow-up running control device for a vehicle using the object detection device for a vehicle according to any one of claims 1 to 4, wherein the relative distance to the preceding vehicle and the relative distance to the preceding vehicle output by the object detection means are provided. Variable cut-off frequency filter means for filtering the relative speed, and a follow-up running control means for making the own vehicle follow the preceding vehicle based on the output of the variable cut-off frequency filter means, the variable cut-off frequency filter means, When the type determination means or the type determination means determines or determines that the preceding vehicle is a large-sized vehicle, a cut-off frequency is reduced, and a follow-up traveling control device for a vehicle is proposed.

According to the above arrangement, the cut-off frequency of the variable cut-off frequency filter means for filtering the relative distance to the preceding vehicle and the relative speed to the preceding vehicle is determined by:
Since it is reduced when the preceding vehicle is determined or determined to be a large vehicle, it is possible to accurately follow the preceding vehicle by compensating for the influence of the fluctuation of the relative distance and relative speed data peculiar to the large vehicle. .

The transmitting / receiving antenna 6 corresponds to the transmitting / receiving means of the present invention.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 13 show an embodiment of the present invention. FIG. 1 is an overall configuration diagram of an object detecting device, and FIG. 2 is a diagram of transmission / reception waves when an object moves closer to a transmission / reception antenna. FIG. 3 is a graph showing a peak signal detected by the detection peak determination means, FIG. 4 is a diagram showing a reflection point of a transmission wave when the preceding vehicle is a passenger car, and FIG. 5 is a graph showing the preceding vehicle. Is a time chart showing a change in the peak signal of the transmitted wave when the vehicle is a passenger car, FIG. 6 is a time chart showing a change in distance data when the preceding vehicle is a passenger car, and FIG. FIG. 8 is a diagram showing a reflection point of a transmitted wave, FIG. 8 is a time chart showing a change in a peak signal of the transmitted wave when the preceding vehicle is a large vehicle, and FIG. 9 is a graph showing a change in distance data when the preceding vehicle is a large vehicle. Time chart shown FIG. 10 is a diagram showing a spectrum distribution peculiar to a large vehicle, FIG. 11 is a diagram showing characteristics of filter means for a passenger car and a large vehicle, FIG. 12 is a first partial diagram of a flowchart for explaining the operation, and FIG. FIG. 7 is a second sub-diagram of a flowchart for explaining the method of FIG.

As shown in FIG. 1, in the object detecting apparatus using the FM-CW wave, the oscillation operation of the oscillator 3 is performed based on the timing signal input from the timing signal generating circuit 1.
As shown by a solid line in FIG. 2A, the transmission wave modulated by the M modulation control circuit 2 and having a frequency modulated in a triangular waveform is separated from the transmission / reception antenna 6 via the amplifier 4 and the circulator 5 into, for example, seven channels. Sent.
When the FM-CW wave is reflected by an object such as a preceding vehicle and the reflected wave is received by the transmitting / receiving antenna 6, the received wave is:
For example, when an object approaches the own vehicle, FIG.
As shown by the broken line, on the rising side where the frequency of the transmitted wave increases linearly, it appears later than the transmitted wave at a lower frequency than the transmitted wave, and on the descending side where the frequency of the transmitted wave decreases linearly. Appears later than the transmitted wave at a higher frequency than the wave.

The received wave received by the transmitting / receiving antenna 6 is input to the mixer 7 via the circulator 5. The mixer 7 includes the oscillator 3 in addition to the reception wave from the circulator 5.
The scanning wave distributed from the transmission wave output from the
As shown in FIG. 2B, the transmission wave and the reception wave are mixed by the mixer 7,
A beat signal having a peak frequency Fup on the rising side where the frequency of the transmission wave increases linearly and a peak signal Fdn on the falling side where the frequency of the transmission wave decreases linearly is generated.

The beat signal obtained by the mixer 7 is
Is amplified to a required level by the A / D converter 1
The amplified data that has been A / D-converted and digitized by 0 at each sampling time is stored and held in the memory 11 in time series. The memory 11 receives a timing signal from the timing signal generation circuit 1. In response to the timing signal, the memory 11 stores data on each of the rising side where the frequency of the transmission / reception wave increases and the falling side where the frequency decreases. Will be stored.

The data stored and held in the memory 11 is inputted to a CPU 12 having a frequency analyzing means 13, a detection peak judging means 14 and an object detecting means 15, and the CPU 12
At 12, the arithmetic processing based on the input data is executed.

The frequency analyzing means 13 is for obtaining a spectrum distribution by frequency-analyzing the data of the beat signal stored in the memory 11.
FFT (Fast Fourier Transform) is used.

The detection peak judging means 14 detects a spectrum (peak signal) at which the detection level is a maximum value when the detection level is equal to or higher than a predetermined threshold, based on the spectrum data obtained by the frequency analysis by the frequency analysis means 13. The rising peak signal shown in FIG. 3A and the falling peak signal shown in FIG. 3B are detected symmetrically with respect to the peak position when the relative speed with respect to the object is “0”. Is done.

The object detecting means 15 calculates the relative distance and relative speed of the object based on the rising peak frequency Fup and the falling peak frequency Fdn obtained by the detected peak judging means 14. Specifically, the distance to the object is calculated based on the sum of the two peak frequencies Fup and Fdn, and the relative speed with the object is calculated based on the difference between the two peak frequencies Fup and Fdn.

The CPU 12 includes the frequency analysis means 1
3. In addition to the detection peak determination means 14 and the object detection means 15, a type determination means 16, a measurement means 17, a type determination means 18, a variable cutoff frequency filter means 19, and a following travel control means 20 are provided.

The type determining means 16 includes a frequency analyzing means 13
It is determined whether the type of the preceding vehicle is a passenger vehicle or a large vehicle based on the spectrum distribution obtained in the above.

FIG. 4 shows a case in which the preceding vehicle is a passenger car. In this case, since the transmission wave from the radar device is mainly reflected on the rear surface of the vehicle body of the preceding vehicle, as shown in FIG. The peak signal of the reflected wave elapses (t → t +
1 → t + 2 → t + 3...). Therefore, as shown in FIG. 6, the data of the relative distance (and relative speed) of the preceding vehicle calculated from the peak signal is also relatively stable.

FIG. 7 shows a case where the preceding vehicle is a large vehicle. In this case, the transmission wave from the radar device is transmitted to the rear of the vehicle body (the rear surface of the bed) and the front of the vehicle (the rear surface of the cabin) of the preceding vehicle. Therefore, as shown in FIG. 8, the peak signal of the reflected wave passes over time (t → t + 1) as shown in FIG.
→ t + 2 → t + 3...). Therefore, as shown in FIG. 9, the data of the relative distance (and relative speed) of the preceding vehicle calculated from the peak signal also becomes unstable.

FIG. 10 shows a spectrum distribution peculiar to a large vehicle obtained by the frequency analysis means 13. FIG.
The example of (a) is a case where a plurality of detection peaks exist in a predetermined frequency region, and the example of FIG. 10 (b) is a case where a gentle detection peak exists over the entire predetermined frequency region. In such a case, the type determining means 16 determines that the preceding vehicle is a large vehicle.

When the type determining means 16 determines that the preceding vehicle is a large vehicle, the measuring means 17 sets the type determining means 16
, The time during which a large vehicle is determined is measured, and if the measured time exceeds a predetermined time, the preceding vehicle is determined to be a large vehicle by the type determination means 18. As described above, when the time during which a large vehicle is determined exceeds the predetermined time, the large vehicle is determined, so that erroneous detection due to the influence of noise or the like can be eliminated.

When it is determined that the preceding vehicle is a large vehicle as described above, the characteristics of the variable cutoff frequency filter means 19 for filtering data of the relative distance and relative speed of the preceding vehicle output from the object detecting means 15 are changed. change. As shown in FIG. 11, the gain of the variable cut-off frequency filter means 19 has a constant value in a low frequency region, and has a characteristic of decreasing linearly when the frequency exceeds a threshold value. When the preceding vehicle is a passenger vehicle, the threshold Fc at which the gain starts to decrease is set to a high frequency (see the solid line), whereas when the preceding vehicle is a large vehicle, the threshold Ft at which the gain starts to decrease Is set to a low frequency (see the broken line).

Based on the data on the relative distance and relative speed of the preceding vehicle output from the variable cut-off frequency filter 19, the following running control means 20 controls the throttle or brake actuator A to follow the preceding vehicle. When the traveling control is performed, the data of the relative distance and the relative speed is shifted to a lower side in the case of a large vehicle having a large variation in the data of the relative distance and the relative speed, so that the data of the optimum relative distance and the relative speed can be adjusted. , And stable follow-up running control can be performed. in this way,
Passenger vehicles and large vehicles can be determined without using special means such as an imaging device. Therefore, in the case of a large vehicle, only changing the cutoff frequency of the variable cut-off frequency filter means 19 to a lower side can be used for passenger vehicles and large vehicles. For any of the above, stable follow-up running control can be performed.

Next, the above operation will be further described with reference to the flowcharts of FIGS.

First, in step S1, attention is paid to the detection spectrum of the detection object for each channel. After setting the counter to "0" in step S2, the detection spectrum tends to be specific to a large vehicle in step S3 (FIG. 10). ), The counter is incremented in step S4. After the search of all seven channels is completed in step S5, if the counter value is equal to or more than the predetermined number A (for example, three or more channels out of seven channels) in step S6, it is determined in step S7 that the detected object is a large vehicle. Make a tentative decision. Then, in step S8, the temporary judgment of the large car is made for a predetermined time B.
If the above is continued, it is finally determined in step S9 that the detected object is a large vehicle.

When the counter value is less than the predetermined number A in step S6, the counter value = 0 has continued for a predetermined time C or more in step S10, and the detected object was previously determined to be a large vehicle in step S11. In step S
At 12, it is determined that the detected object is a passenger car. Further, if the provisional judgment of the large vehicle has not continued for the predetermined time B or more in the step S8, the counter value = 0 has not continued for the predetermined time C or more in the step S10, or if the detected object has been previously large in the step S11. If it is not determined that the vehicle is a car, the previous determination (passenger car or large car) is continued in step S13.

If it is determined in step S14 that the vehicle is a large vehicle, the filter constants of the relative distance and the relative speed are set to Ft in step S15. If it is determined in step S14 that the vehicle is a passenger vehicle, the relative distance and the relative speed are determined in step S16. The speed filter constant is set to Fc (see FIG. 11).

Although the embodiments of the present invention have been described above, various design changes can be made in the present invention without departing from the gist thereof.

For example, the measuring means 17 and the type determining means 18 in the embodiment are not always necessary. When the type determining means 16 determines that the preceding vehicle is a large vehicle, the cutoff frequency of the variable cutoff frequency filter means 19 is changed. You may change it.

[0040]

As described above, according to the first aspect of the present invention, in a vehicle object detection apparatus using an FM-CW wave, a beat obtained by mixing a transmission wave and a reception wave with a mixer. Since the signal is subjected to frequency analysis and the type of the object is determined based on the detection spectrum shape obtained as a result,
The type (shape) of an object can be determined without using an imaging device such as a television camera.

According to the invention described in claim 2,
The time when it is determined that the object types are the same is measured, and when the time is equal to or longer than a predetermined value, the object type is determined. Can be determined.

According to the invention described in claim 3,
When the detected spectrum shape obtained by the frequency analysis has a plurality of peaks within a predetermined range, the object is determined to be a large vehicle, so that a large vehicle having a plurality of reflection surfaces can be accurately determined.

According to the fourth aspect of the present invention,
If the detected spectrum shape obtained by the frequency analysis is widely distributed within a predetermined range, the object is determined to be a large vehicle, so that a large vehicle having a wide reflecting surface can be accurately determined.

According to the invention described in claim 5,
The cutoff frequency of the variable cutoff frequency filter means for filtering the relative distance to the preceding vehicle and the relative speed to the preceding vehicle is reduced when the preceding vehicle is determined or determined to be a large vehicle. It is possible to accurately follow the preceding vehicle by compensating for the influence of the specific data of the relative distance and the relative speed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an object detection device.

FIG. 2 is a graph showing waveforms and peak frequencies of transmission / reception waves when an object is moving closer to a transmission / reception antenna;

FIG. 3 is a graph showing a peak signal detected by a detection peak determination unit.

FIG. 4 is a diagram showing reflection points of a transmission wave when a preceding vehicle is a passenger vehicle;

FIG. 5 is a time chart showing a change in a peak signal of a transmission wave when a preceding vehicle is a passenger vehicle;

FIG. 6 is a time chart showing a change in distance data when a preceding vehicle is a passenger vehicle;

FIG. 7 is a diagram showing reflection points of transmission waves when a preceding vehicle is a large vehicle.

FIG. 8 is a time chart showing a change in a peak signal of a transmission wave when a preceding vehicle is a large vehicle.

FIG. 9 is a time chart showing a change in distance data when the preceding vehicle is a large vehicle.

FIG. 10 is a diagram showing a spectrum distribution peculiar to a large vehicle.

FIG. 11 is a diagram showing characteristics of filter means for passenger cars and large cars.

FIG. 12 is a first partial diagram of a flowchart for explaining the operation;

FIG. 13 is a second partial diagram of a flowchart for explaining the operation;

[Explanation of symbols]

 Reference Signs List 6 transmission / reception antenna (transmission / reception means) 7 mixer 13 frequency analysis means 14 detection peak determination means 15 object detection means 16 type determination means 17 measurement means 18 type determination means 19 variable cut-off frequency filter means 20 tracking travel control means

Continued on the front page F term (reference) 5H180 AA01 CC12 CC14 LL01 LL04 LL09 5J070 AD01 AE01 AF03 AH25 AH40 AK22 BA01

Claims (5)

[Claims] A transmitting / receiving means for transmitting an FM-CW wave and receiving a reflected wave of the FM-CW wave from an object; and a mixer for generating a beat signal by mixing the transmitted wave and the received wave. 7), frequency analysis means (13) for frequency-analyzing the beat signal obtained by the mixer (7), and a peak signal obtained based on the frequency analysis results on the ascending and descending sides by the frequency analyzing means (13). A detection peak determining means for determining a peak signal equal to or larger than a threshold as a detection peak; and a relative distance to an object based on the ascending and descending detection peaks obtained by the detection peak determining means. Object detection means (15) for calculating at least one of the relative velocities with respect to the object, wherein the detection spectrum obtained by frequency analysis by the frequency analysis means (13) is provided. Object detecting apparatus for a vehicle characterized by comprising type determination means (16) determines the type of the object based on the tram shape. 2. A measuring means (1) for measuring a time when the type of the object is determined to be the same by the type determining means (16).
7) a type determining means (18) for determining the type of the object when the time measured by the measuring means (17) is equal to or more than a predetermined value;
The vehicle object detection device according to claim 1, further comprising: 3. The type determining means (16) determines that the object is a large vehicle when the detected spectrum shape obtained by the frequency analyzing means (13) has a plurality of peaks within a predetermined range. The object detection device for a vehicle according to claim 1, wherein the object detection device is a vehicle. 4. The type determining means (16) determines that the object is a large vehicle when the detected spectrum shape obtained by the frequency analyzing means (13) is widely distributed within a predetermined range. The object detection device for a vehicle according to claim 1, wherein the object detection device is a vehicle. 5. A follow-up running control device for a vehicle using the vehicle object detection device according to claim 1, wherein a preceding vehicle output by the object detection means (15) is provided. Variable cut-off frequency filter means (19) for filtering the relative distance of the vehicle and the relative speed with respect to the preceding vehicle; and a follow-up traveling for causing the own vehicle to follow the preceding vehicle based on the output of the variable cut-off frequency filter means (19). Control means (20), and the variable cut-off frequency filter means (19) is provided when the type determination means (16) or the type determination means (18) determines or determines that the preceding vehicle is a large vehicle. A follow-up running control device for a vehicle, wherein the cut-off frequency is reduced.