JPH09145827A - Fm-cw radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the processing of radar signals regarding an FM-CW radar device ideal as a device for accurately detecting a plurality of objects existing in front of a vehicle. SOLUTION: An FM-CW radar for scanning a detection area in front of a vehicle is provided to scan in regular order from an area 1 to collect object data. Only a peak caused by an object 50 appears in the spectral analysis result of the area 1, and only a peak caused by an object 52 appears in the spectral analysis result of an area 3. Peaks caused by the objects 50, 52 arise in the spectral analysis result of an area 2. As to a plurality of peaks included in the spectral analysis result of the area 2, the peaks already determined to be paired in the area 1 or 3 are combined first, and then remaining peaks are paired.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FM-CW radar device, and more particularly to an FM-CW radar device suitable as a device for accurately detecting a plurality of objects existing in front of a vehicle.

[0002]

2. Description of the Related Art Conventionally, a technique for realizing an on-vehicle radar device by using an FM-CW radar device has been proposed.
For example, Japanese Patent Application Laid-Open No. 7-49377 discloses a steer-type vehicle-mounted radar device that uses an FM-CW radar device as a target object detection mechanism. The above radar device has a function of estimating the position of a preceding vehicle traveling on its own lane from the traveling state of the vehicle and steering the radar antenna of the FM-CW radar device at that angle. According to such a configuration, the possibility of losing the preceding vehicle while traveling on a curve can be reduced, so that a high object recognition accuracy can be obtained in the vehicle-mounted radar device.

In the FM-CW radar device, a transmission wave whose frequency is increased or decreased at a predetermined change rate is transmitted from the radar antenna toward the detection area. When the target object exists in the detection area, the reflected wave reaches the target object and the reflected wave is generated after the propagation time τ according to the distance between the target object and the radar antenna. The generated reflected wave reaches the radar antenna after a propagation time τ according to the distance between the object and the radar antenna.

In the FM-CW radar device, the reflected wave that reaches the radar antenna and the transmitted wave at that time are mixed as described above, and the frequency deviation between the reflected wave and the transmitted wave is made into a fluctuating frequency, and the reflected wave is reflected. A beat signal having an amplitude according to the intensity of is generated. When the beat signal generated as described above is subjected to known FFT processing and frequency analysis is performed, the spectrum intensity of each frequency component included in the beat signal can be obtained. The FM-CW radar device includes a spectrum analysis result (hereinafter, referred to as an upstream section spectrum) of a beat signal obtained in a process of rising a reflected wave and a spectrum of a beat signal obtained in a process of falling a reflected wave. By using the analysis result (hereinafter referred to as the downlink spectrum), the distance to the object and the FM
Compute the relative speed of the object to the CW radar device.

When a plurality of objects exist in the detection area of the FM-CW radar device, a reflected wave is generated for each object. When a plurality of reflected waves are generated in this way, a plurality of spectral peaks are formed in the spectrum analysis result of the beat signal. In this case, in order to accurately detect a plurality of objects, it is necessary to properly combine the plurality of spectral peaks included in the upstream section spectrum and the plurality of spectral peaks included in the downstream section spectrum.

The above-mentioned conventional vehicle-mounted radar apparatus uses a frequency pairing method for pairing the spectrum peaks in the order of frequencies when a plurality of spectrum peaks are present in the upstream spectrum and the downstream spectrum, and the shape of the spectrum peaks. Correlation calculation is performed, and both of the correlation pairing methods of pairing those having a high correlation are used to realize proper pairing.

When there are no large relative velocity differences among a plurality of objects existing in the detection area, the peak spectrum of the object having a small relative distance is on the low frequency side in both the up-section spectrum and the down-section spectrum. In addition, the peak spectrum of an object with a large relative distance appears on the high frequency side. Therefore, under such circumstances, accurate pairing can be performed by the above method.

On the other hand, when a plurality of objects existing in the detection area have a large relative velocity difference, the spectral peaks for the same object are in different orders in the upstream section spectrum and the downstream section spectrum. May appear in. In this case, the above method cannot perform accurate pairing. However, the spectral peaks appearing in the upstream spectrum and the spectral peaks appearing in the downstream spectrum show a high correlation in shape when they are caused by the same object, while they are the same. The shape does not show a high correlation unless it is caused by the object. Therefore, after pairing is performed by the above method, by obtaining the degree of correlation of the paired spectral peaks,
It is possible to determine whether proper pairing has been performed. Further, when it is determined that the correlation is low, if pairing is performed again by the above method, accurate pairing can be performed.

Therefore, according to the above-described conventional on-vehicle radar device, when a plurality of objects exist within the irradiation range of the FM-CW radar device, the plurality of objects can be recognized with high accuracy. You can Further, as described above, the conventional vehicle-mounted radar device includes the F-type, including when the vehicle is turning.
The M-CW radar device can accurately illuminate the lane. Therefore, according to the above-described conventional vehicle-mounted radar device, it is possible to obtain an effect that a plurality of objects existing on the own lane can be accurately detected.

[0010]

In order to monitor the front of the vehicle widely, it is effective to use the on-vehicle radar device as a scanning radar device. F for the object detection mechanism
According to the scanning radar device using the M-CW radar device, the distance to the target object and the relative speed of the target object can be detected for each of the plurality of target objects existing in a relatively wide detection area. It is possible to detect the direction in which the object exists with respect to the host vehicle.

In order to detect the existence direction of the object with respect to the own vehicle with high accuracy, it is necessary to calculate the up-section spectrum and the down-section spectrum for each predetermined scanning angle and perform the object detection process for each scanning angle. is necessary. Therefore, in order to realize such a function, that is, in order to sufficiently obtain the benefit of using the on-vehicle radar device as the scanning radar device, the detection region is divided into a plurality of regions, and the spectrum is divided for each division. It is necessary to analyze and appropriately pair the spectrum peaks included in the upstream section spectrum and the downstream section spectrum calculated for each section.

The above arithmetic processing can be performed by subjecting the spectrum analysis results calculated for all the sections to the pairing processing by the above-mentioned method and. However, if such arithmetic processing is performed, the arithmetic load of the vehicle-mounted radar device becomes excessive, resulting in a disadvantage in cost or responsiveness. In this sense, the calculation method of the conventional device is not necessarily the optimum calculation method in the scanning radar device using the FM-CW radar device.

The present invention has been made in view of the above points, and performs pairing between a spectrum peak included in an upstream section spectrum and a spectrum peak included in a downstream section spectrum by using scanning angle data. It is an object of the present invention to provide an FM-CW radar device that solves the above problems by simply performing it.

[0014]

The above object is achieved by the present invention.
And a beat signal generation mechanism that generates a beat signal based on the reflected wave and the transmitted wave with respect to the transmitted wave, and a frequency modulation mechanism that modulates the frequency of the transmitted wave at a predetermined change rate. A spectrum analysis mechanism for detecting the spectrum intensity of each frequency component, and a spectrum analysis result about a beat signal obtained in the process of increasing the frequency of the transmission wave, and a beat obtained in the process of decreasing the frequency of the transmission wave. FM- which detects the distance to the object reflecting the transmitted wave and the relative speed of the object by combining with the spectrum analysis result of the signal.
In the CW radar, a scanning unit that scans a predetermined detection area with the transmission wave, a peak spectrum included in a spectrum analysis result obtained in the process of increasing the frequency of the transmission wave, and a frequency of the transmission wave decrease. This is achieved by an in-vehicle scanning radar device including a spectrum pairing unit that pairs the peak spectrum included in the spectrum analysis result obtained in the process based on the scanning angle data of the scanning unit.

In the present invention, the transmitted wave is applied in the scanning angle direction determined by the scanning means. When the object exists in the irradiation direction of the transmitted wave, a beat signal reflecting the distance to the object and the relative speed of the object is generated. When the beat signal obtained in the process of increasing the frequency of the transmitted wave is frequency-analyzed, an upstream spectrum is obtained. Further, when the beat signal obtained in the process of decreasing the frequency of the transmitted wave is frequency-analyzed, a downlink spectrum is obtained. The spectral peaks included in the upstream section spectrum and the spectral peaks included in the downstream section spectrum reflect the distance to the object that caused the spectrum peaks and the relative speed of the object. When multiple spectrum peaks are included in the upstream and downstream spectrums, it is possible to detect the distance to the target and the relative speed of the target for multiple targets by appropriately combining the spectrum peaks. Is possible. In the present invention, the upstream section spectrum and the downstream section spectrum are calculated for each scanning angle. The spectrum pairing means pairs the spectrum peak in the upstream section spectrum calculated for each scan angle and the spectrum peak in the downstream section spectrum based on the scan angle data. As a result of considering the scan angle data, pairing of spectral peaks is facilitated.

[0016]

1 is a system configuration diagram of an on-vehicle scanning radar device according to an embodiment of the present invention. The device of this embodiment is controlled by a radar electronic control unit 10 (hereinafter referred to as a radar ECU) and an environment recognition vehicle speed control electronic control unit 12 (hereinafter referred to as an environment recognition ECU).

A radar antenna 14 and a scanning controller 16 are connected to the radar ECU 10. The radar antenna 14 is an FM-CW (Frequency Modulati
on-Continuous Wave) This is a component of a radar, and is disposed, for example, near the front grill of a vehicle so as to be rotatable about a rotary shaft 14a extending in the vertical direction. The radar antenna 14 is a directional antenna, and transmits and receives signals within a predetermined irradiation range.

A scanning mechanism 18 is connected to the radar antenna 14. The scanning mechanism 18 includes the radar antenna 14
Is a device for oscillating, and is feedback-controlled by the scanning controller 16. Scan controller 16
A scanning angle signal is supplied from the radar ECU 10. The scanning controller 16 includes a radar antenna 14
The scanning mechanism 18 is feedback-controlled so that the scanning angle of is in agreement with the command angle θ _S from the radar ECU 10. The radar ECU 10 increases / decreases the command angle θ _S of the scanning angle in a predetermined cycle so that a predetermined detection area in front of the vehicle is scanned by the radar antenna 14 at a predetermined speed.

The radar ECU 10 includes a radar antenna 1
By applying appropriate processing to the signal supplied from 4,
An object existing in the detection area in front of the vehicle is detected, and the detection result is supplied to the environment recognition ECU 12. Environmental awareness E
An alarm device 20, a brake 22, and a throttle 24 are connected to the CU 12. The environment recognition ECU 12
When the object is close to the front of the vehicle, the alarm 20, the brake 22, or the throttle 24 is driven according to a preset logic to call the attention of the vehicle occupant and to decelerate the vehicle.

FIG. 2 is a block diagram showing the radar ECU 10 functionally. The radar ECU 10 is a device mainly composed of a microcomputer. The radar ECU 10 can be functionally represented by a scanning angle control unit 26, a radar signal processing unit 28, and an object recognition unit 30, as shown in FIG. The scan angle control unit 26 is a block that supplies a scan angle signal to the scan controller 16 described above. The scanning angle command value θ _S included in the scanning angle signal is changed in synchronization with the control timing of the radar signal processing unit 28.

The radar signal processing section 28 constitutes an FM-CW radar together with the radar antenna 14. When an object exists in the scanning angle direction of the radar antenna 14, the radar signal processing unit 28 is supplied with a signal related to the object. When such a signal is supplied, the radar signal processing unit 28 generates a spectrum analysis result in which the inter-vehicle distance between the object and the own vehicle and the relative speed are reflected, and associates the result with the scanning angle to obtain the object. It is supplied to the recognition unit 30. The configuration of the radar signal processing unit 28 will be described later in detail with reference to FIG.

The object recognition unit 30 is a radar signal processing unit 2
Based on the spectrum analysis result supplied from 8, data on the object is calculated for each scanning, and from the calculation result, the position of the object existing in the detection area set in front of the vehicle and the object are calculated. The distance and the relative speed of the object are calculated. The system of the present embodiment is provided with the object recognition unit 30.
However, it is characterized in that the spectrum analysis result supplied from the radar signal processing unit 28 is processed by a method described later.

FIG. 3 is a block diagram showing a functional representation of the radar signal processing unit 28 described above. The radar antenna 14 described above, as shown in FIG.
And functions as the receiving antenna 14c. The carrier wave generation circuit 32, the frequency modulation circuit 34, the modulation voltage generation circuit 36, and the directional coupler 3 included in the radar signal processing unit 28.
Reference numeral 8 constitutes a transmission side circuit of the FM-CW radar.

The carrier wave generation circuit 32 generates a carrier wave having a predetermined frequency and supplies the carrier wave signal to the frequency modulation circuit 34. On the other hand, the modulation voltage generation circuit 36 generates a triangular wave whose amplitude changes in a triangular shape, and supplies the triangular wave to the frequency modulation circuit 34. The frequency modulation circuit 34 uses the triangular wave supplied from the modulation voltage generation circuit 36 as a modulation signal,
The carrier wave supplied from the carrier wave generation circuit 32 is frequency-modulated.

The waveform shown by the solid line in FIG. 4 (A) shows the changing state of the frequency of the signal appearing at the output terminal of the frequency modulation circuit 34. As a result of the frequency modulation described above, the output terminal of the frequency modulation circuit 34 has a predetermined variation width Δf and a modulation frequency fm (= 1 / T) with the passage of time, as indicated by the solid line in FIG. ; T represents a modulation wave signal that is modulated in a triangular wave shape with a fluctuation period of the triangular wave generated from the modulation voltage generation circuit 36). The modulated wave signal appearing at the output terminal of the frequency modulation circuit 34 is supplied to the transmitting antenna 14b via the directional coupler 38 and is also supplied to the mixer 40 described later.

The modulated wave signal supplied to the transmitting antenna 14b as described above is transmitted in the scanning angle direction of the transmitting antenna 14b. When the object exists in the scanning angle direction, the transmission signal is reflected by the object and the reflected wave is received by the receiving antenna 14c. The mixer 40 is connected to the receiving antenna 14c. Radar signal processing unit 2
Reference numeral 8 denotes a mixer 4 as a receiving circuit of the FM-CW radar.
0, an amplifier circuit 42, a filter 44, and a fast Fourier transform processing circuit 46 (hereinafter referred to as an FFT signal processing circuit). The signal received by the receiving antenna 14c is
The data is processed by the receiving circuit and converted into data representing the inter-vehicle distance and the relative speed between the object and the vehicle.

Waveforms shown by a broken line and an alternate long and short dash line in FIG. 4 (A) respectively show the change state of the frequency of the reflected signal supplied from the receiving antenna 14c to the mixer 40. Mixer 4
At 0, the reflected signal and the transmission signal supplied from the directional coupler 38 are mixed to generate a beat signal having a frequency difference between them as a fluctuating frequency.

FIG. 4B shows how the frequency of the beat signal changes. Hereinafter, as shown in FIG. 4B, the frequency of the beat signal generated in the section where the frequency of the transmission signal rises is the up frequency fup, and the frequency of the beat signal generated in the section where the frequency of the transmission signal falls is Downlink frequency f
It is called down.

The beat signal generated by the mixer 40 is amplified by the amplifier circuit 42 and then supplied to the filter 44. The filter 44 separates the beat signal supplied from the amplifier circuit 42 into a beat signal in the rising section and a beat signal in the falling section. The separated beat signals are both FFT
It is supplied to the signal processing circuit 46. FFT signal processing circuit 4
6 performs FFT processing on the beat signal of each section,
A power spectrum for the up frequency fup (hereinafter referred to as the up section spectrum) and a power spectrum for the down frequency fdown (hereinafter referred to as the down section spectrum) are calculated.

FIG. 5A shows an upstream spectrum calculated by the FFT signal processing circuit 46 when two objects are present in the scanning angle direction of the radar antenna 14. Further, FIG. 5B shows a downlink section spectrum calculated by the FFT signal processing circuit 46 under the same environment.

When there are a plurality of objects in the scanning angle direction of the radar antenna 14, the receiving antenna 14c receives reflected waves for each of the objects. In this case, the mixer 40 forms a beat signal for each of the plurality of received signals. As a result, the FFT signal processing circuit 4
At 6, a power spectrum with multiple peaks is detected.

By the way, if there is no relative velocity between the vehicle and the object, the object and the vehicle are separated between the transmitted wave transmitted from the transmitting antenna 14b and the reflected wave reaching the receiving antenna 14c. There is a phase difference depending on the time it takes for the signal to propagate between them. In this case, since the Doppler shift is not superimposed on the frequency of the reflected wave, the waveform representing the frequency fluctuation of the reflected wave is obtained by simply translating the waveform of the transmission signal temporally in parallel as shown by the alternate long and short dash line in FIG. Only the waveform becomes. Therefore, the up frequency fup and the down frequency fdo
Both wn have the same value as indicated by the alternate long and short dash line in FIG. At this time, both fup and fdown are values corresponding to the inter-vehicle distance between the object and the vehicle.

On the other hand, the relative speed Vr between the vehicle and the object is
, The Doppler shift corresponding to the relative velocity Vr is superimposed on the frequency of the reflected wave. Therefore, for example, when the object and the vehicle tend to approach each other, the frequency of the reflected wave shifts to the high frequency side as a whole. As a result, as the waveform representing the frequency of the reflected wave, as shown by the broken line in FIG. 4 (A), the waveform that is temporally translated in accordance with the distance (the waveform indicated by the one-dot chain line in the figure) is on the higher frequency side. The waveform becomes a waveform translated in parallel to.

When the frequency of the reflected wave is shifted to the high frequency side as described above, fup is small and fdown is largely changed as compared with the case where the relative velocity Vr is "0". At this time, if the average value of fup and fdown is calculated as shown in the following equation, the Doppler shift component superimposed on fup and the Doppler shift component superimposed on fdown cancel each other out, and the distance between the object and the vehicle is reduced. A characteristic value corresponding to the distance can be obtained.

Fr = (fup + fdown) / 2 (1) The deviation between fup and fdown corresponds to the sum of the Doppler shift component superimposed on fup and the Doppler shift component superimposed on fdown. Therefore, as shown in the following equation, when the value of 1/2 of the deviation between the two is obtained, the value becomes a characteristic value corresponding to the Doppler shift component caused by the relative speed between the vehicle and the object.

Fd = (fdown−fup) / 2 (2) In this embodiment, the center frequency of the modulated wave signal generated by the frequency modulation circuit 34 is f ₀ , the modulation frequency is fm, and the modulation width is Δf. In addition, when the propagation speed of the transmission signal is high speed c and if there is an object having the relative speed Vr at positions separated by the distance L, the relationship shown in the following equation is established.

Fr = 4fm · Δf · L / c (3) fd = 2Vr · f ₀ / c (4) Therefore, in the FFT signal processing circuit 46, the spectrum peak indicating the up frequency fup and the down peak When the spectrum peaks representing the frequency fdown are obtained, they are substituted into the above equations (1) and (2) to obtain fr and fd, and the calculated values thereof are given in the above equations (3) and (4). By substituting into the formula, the inter-vehicle distance L and the relative speed Vr regarding the object existing in the scanning angle direction of the radar antenna 14 can be obtained.

As described above, FIG. 5 (A) and FIG. 5 (B)
4A is a spectrum analysis result when two objects exist in the scanning angle direction of the radar antenna 14. More specifically, the spectrum appearing at the position of frequency FM _U1 in FIG. 5A and the spectrum appearing at the position of frequency FM _d1 in FIG. 5B are caused by one object existing in the scanning angle direction. It is a peak that appears. FIG.
The spectrum appearing at the position of frequency FM _U2 in (A) and the spectrum appearing at the position of frequency FM _d2 in FIG. 5B are peaks appearing due to other objects existing in the scanning angle direction.

The spectrum analysis result as shown in FIG. 5 was obtained.
If you get FM_U1And FM_d1In combination with
By performing the calculation using the equations (1) to (4),
To obtain the inter-vehicle distance L and the relative speed Vr related to the object
With the ability to_U2And FM _d2Combined with
By performing calculations like
The separation L and the relative speed Vr can be obtained. like this
In the system of this embodiment, a set of spectra
Obtaining data on multiple objects from analysis results
Can be.

As described above, the radar antenna 14 is scanned by the scanning mechanism 18. FIG. 6 shows an area set as the scanning area of the radar antenna 14 in the vehicle 48 equipped with the system of this embodiment. As shown in FIG. 6, in the present embodiment, an area having a spread of 10 ° to the left and right with respect to the longitudinal axis of the vehicle 48 is an area scanned by the radar antenna 14, that is, an object detection area. Has been done. In the following description, a region on the left side of the axis of the vehicle 48 has a negative scanning angle θ _S , and a region on the right side of the axis of the vehicle 48 has a positive scanning angle θ _S.

FIG. 7 shows the scanning angle θ _{S of the} radar antenna 14.
And the frequency f of the transmission signal. As mentioned above,
In the system of this embodiment, the radar signal processing unit 28
The scanning angle θ _S of the radar antenna 14 is controlled in synchronism with the processing of. More specifically, the radar antenna 14 is controlled so that the scanning angle θ _S changes by 0.5 ° while the frequency f of the transmission signal changes by one cycle as shown in FIG. 7.
In addition, in this embodiment, the radar antenna 14 has about 1
It is controlled so that an area of −10 ° to + 10 ° is scanned every 00 msec.

According to the system of the present embodiment, one set of the upstream section spectrum and the downstream section spectrum is detected, so that the data regarding the object can be calculated. As described above, if the scanning angle θ _S changes by 0.5 ° while the frequency f of the transmission signal changes by one cycle, a set of upstream section spectra is obtained every time the scanning angle θ _S changes by 0.5 °. And the downlink section spectrum can be obtained. Therefore,
According to the system of this embodiment, the data on the object can be calculated every time the radar antenna 14 is scanned by 0.5 °.

That is, in the system of this embodiment,
The detection area in front of the vehicle 48 is divided into 40 detection areas at intervals of 0.5 °, and the radar antenna 14 scans the scanning angle θ _S −.
While scanning the area of 10 ° to + 10 °, that is, within about 100 msec, 40 sets of spectrum analysis results shown in FIGS. 5A and 5B can be obtained. The radar signal processing unit 28 described above supplies the 40 sets of spectrum analysis results to the object recognition unit 30 in association with the scanning angle θ _S of the radar sensor 20 as the radar antenna 14 is scanned. To do.

FIG. 8 shows a state in which objects 50 and 52 are present in front of a vehicle equipped with the system of this embodiment. The target object 50 is a fixed object such as a pole of a guardrail, and the target object 52 is a preceding vehicle running on a road.
As described above, in the system of this embodiment, one set of spectrum analysis results is obtained every time the radar antenna 14 is scanned by 0.5 °. Further, the radar antenna 14 transmits / receives transmitted / received waves with a predetermined spread. Therefore, the detection area secured by the radar antenna 14 being scanned by 0.5 ° is within the range of 0.5 °.
4 is the range including the spread of transmitted / received waves. Boundary lines shown by solid lines in FIG. 8 indicate boundary lines (hereinafter, referred to as area dividing lines) that divide the detection area at intervals of 0.5 °. Further, the boundary line shown by the broken line in FIG.
2 shows a spread range of transmitted / received waves of the radar antenna 14 in the case where the scanning direction of is overlapped with the area dividing line.

When the scanning direction of the radar antenna 14 changes from the state where it overlaps with the area dividing line shown on the leftmost side in FIG. 8 to the state where it overlaps with the area dividing line adjacent to the right side of the area dividing line, FIG. The area indicated by is scanned. Similarly, thereafter, every time the scanning direction of the radar antenna 14 changes by 0.5 °, the area shown by and the area shown by are sequentially scanned. Each of these areas ~ has a portion overlapping with an adjacent area. Therefore, the object located near the boundary of each area is
It will be detected as an object in two regions.

In the situation shown in FIG. 8, the object 50 is
It exists in a region where regions overlap. Further, the target object 52 exists in a region where regions overlap with each other. Therefore, the object 50 will be detected in the area and the area, and the object 52 will be detected in the area and respectively.

FIGS. 9A and 9B show an upstream section spectrum and a downstream section spectrum for a region, respectively. In these spectrum analysis results, peak spectra Su ₅₀ and Sd ₅₀ due to the object 50 appear. Since the target object 50 is an object fixed on the road, the target object 50 and the vehicle equipped with the system of this embodiment are
There is a large relative velocity between and. Therefore, the position where the peak spectrum Su ₅₀ appears in the upstream spectrum and the peak spectrum Sd ₅₀ in the downstream spectrum.
Is relatively distant from the position where appears.

10 (A) and 10 (B) show the upstream section spectrum and the downstream section spectrum for the region, respectively. In these spectrum analysis results, peak spectra Su ₅₀ , S due to the object 50 are included.
In addition to d ₅₀ , the peak spectrum S due to the object 52
u ₅₂ and Sd ₅₂ appear. Since the object 52 is traveling on the road, there is not a relatively large relative speed between the vehicle equipped with the system of the present embodiment and the object 52. Therefore, the peak spectrum Su is included in the upstream section spectrum.
_The position where ₅₂ appears and the position where the peak spectrum Sd ₅₂ appears in the downlink spectrum are relatively close to each other.

11 (A) and 11 (B) show the upstream section spectrum and the downstream section spectrum for the region, respectively. In these spectrum analysis results, the peak spectra Su ₅₀ , S due to the object 52 are included.
Only d ₅₀ appears. In addition, FIG.
(B) represents an upstream section spectrum and a downstream section spectrum for each region. Since no object is present in the region, no peak spectrum appears in these spectral analysis results.

As shown in FIG. 9 (A) and FIG. 9 (B), or as shown in FIG. 11 (A) and FIG. 11 (B),
If one peak spectrum appears in each of the upstream and downstream spectrums, simply combine the spectrum peaks and then perform the above (1).
By performing the calculation based on the expressions (4) to (4), it is possible to accurately obtain the data regarding the object.

However, as shown in FIG. 10 (A) and FIG. 10 (B), when there are a plurality of spectrum peaks in each of the upstream spectrum and the downstream spectrum, pairing of the spectrum peaks may be performed. is necessary. When there are large relative velocity differences among a plurality of objects that are detected at the same time, such as the objects 50 and 52 described above, the order in which the peak spectra resulting from those objects appear in the up-segment spectrum and the down-segment spectrum. The order in which they appear may be reversed.
Therefore, an exact combination may not be obtained by simply pairing a plurality of peak spectra in order of frequency.

In the present embodiment, when a plurality of peak spectra are detected in a specific scanning region, the pairing of the peak spectra is performed in consideration of the factor of the scanning angle θ _S , so that such pairing is facilitated. Moreover, it is characterized in that it can be performed accurately. The pairing method executed in this embodiment will be described below with reference to FIGS. 13 and 14.

13 and 14 are flowcharts showing an example of a control routine executed by the radar ECU 10 so as to realize the above functions. The routines shown in FIGS. 13 and 14 are routines that are started every about 100 msec each time the scanning of the radar antenna 14 is started.

When the routines shown in FIGS. 13 and 14 are started, first in step 100, the counter i is incremented. Counter i is radar antenna 1
A counter representing the number of the area scanned by 4.
"0" is set by the initial processing. Therefore, immediately after this routine is started, i is set to "1" in step 100.

At step 102, it is judged if the data input for the area i is completed, that is, if the scanning of the area i is completed. When it is determined that the data input is not yet completed, the determination of the repeating step 102 is performed until it is determined that the data input is completed. If it is determined that the data input is completed, step 1
At 04, signal processing is performed to obtain an up link spectrum and a down link spectrum.

When the processing of step 104 is completed,
Next, at step 106, it is judged if the number of peak spectra included in the spectrum analysis result is larger than "1". The number of peaks is not greater than "1",
That is, when it is determined that the number of peaks is “1”, accurate pairing can be obtained by simply combining the peak spectrum included in the upstream section spectrum and the peak spectrum included in the downstream section spectrum. . Therefore, if the above determination is made,
Steps 108 and 110 are jumped, and the process of step 112 is executed.

If it is determined in step 106 that the number of peaks is larger than "1", step 108 is performed.
In, the peak spectrum included in the upstream section spectrum and the peak spectrum included in the downstream section spectrum are paired in order of frequency. Next, step 1
At 10, it is determined whether or not the correlation degree of the paired peak spectrum is _{equal to} or larger than a predetermined threshold value α _TH . The correlation degree of the peak spectrum is calculated based on the shape of the peak spectrum and the like. When the paired peak spectra are caused by the same object, a high degree of correlation is obtained. In this case, step 1 above
The condition of 10 is satisfied. On the other hand, when the paired peak spectra are caused by different objects, a low degree of correlation is calculated. In this case, the condition of step 110 is not satisfied.

If it is determined that the condition of step 110 is satisfied, it is determined that the plurality of peak spectra are properly paired, and then, in step 112, the object is determined based on the paired peak spectra. Data, that is, the inter-vehicle distance L between the object and the own vehicle, and the relative speed Vr of the object with respect to the own vehicle
Are calculated and those calculated values are stored together with the number i of the scanning area.

On the other hand, if it is determined that the condition of step 110 is not satisfied, it is determined that the plurality of peak spectra are not properly paired, and the spectrum information is held in step 114. .
In the present embodiment, the scanning region number i, the peak spectrum level, and the position (frequency) at which the peak spectrum is detected are held as spectrum information.

When the above process is completed, the next step 1
At 16, it is determined whether or not the counter i has reached the predetermined value n. The predetermined value n is a number given to the final scanning area. If i ≧ n is not satisfied, it is determined that the data collection for all the scanning regions has not been completed. In this case, the processes in steps 100 to 114 are repeatedly executed until it is determined that the condition i ≧ n is satisfied. On the other hand, when it is determined that i ≧ n is satisfied, it is determined that the data collection for all the scanning regions is completed. In this case, after the counter i is reset to "0" in step 118, the processing from step 120 onward shown in FIG. 14 is executed.

In step 120, the above step 114
In the area where the spectrum information is held, that is, in the area where the combination of the peak spectra is not fixed (hereinafter referred to as an uncertain area), the number of one area is substituted for the variable j. It should be noted that the one area is determined to be, for example, the area with the smallest number or the area with the largest number among the uncertain areas, or the area corresponding to the front of the host vehicle.

At step 122, the variable k is "j-1".
Is substituted. Next, at step 124, it is judged if the combination of the peak spectra of the region k is fixed. If the region k is also an uncertain region, it is determined that the above condition is not satisfied. In this case, thereafter, it is determined in step 126 whether k is smaller than j, and the process of step 128 or step 130 is executed according to the determination result. As mentioned above, the variable k is initially set to j-1. If k is j-1, the condition of step 126 is satisfied. In this case, thereafter, after k is decremented in step 128, the process of step 124 is executed again. In this case, the region k
Until it is discriminated that is a definite area, it is sequentially determined whether or not the area having a smaller number is the definite area. Also, as described below, the variable k is j + 1 under certain circumstances.
May be set to. In such a case, it is determined that the condition of step 126 is not satisfied, and step 13
After k is incremented by 0, the above step 124 is performed.
The process of is executed again. In this case, until it is determined that the region k is the confirmed region, the determination of whether or not the region having the larger number is the confirmed region is sequentially performed.

When it is determined in step 124 that the region k is the definite region, in step 132, the k region, that is, the peak spectrum included in the definite region exists in the uncertain region adjacent to the k region. It is determined whether or not. If overlapping peak spectra (hereinafter referred to as overlapping peaks) exist in both, the peak spectra in the uncertain region can be easily and accurately paired based on the combination of the already determined peak spectra. On the other hand, if there is no overlap between the two, pairing by this method is not possible. In this case, in step 134, j + 1 is assigned to the variable k, and thereafter,
The search for a definite area having a larger number than area j is started.

If it is determined in step 132 that there are overlapping peaks in the uncertain region, in step 136, the process of pairing the overlapping peaks in the spectrum analysis result of the uncertain region is executed. When the overlapping peaks are paired, the number of peaks remaining in the spectrum analysis result of the uncertain region is reduced, which facilitates pairing. Thereafter, in step 138, the peak spectrum remaining in the spectrum analysis result of the uncertain region is paired by the frequency pairing method and the correlation pairing method.

When the above processing is completed, next, at step 140, it is judged if the peak spectra have been determined for all the regions. As a result, when it is determined that the uncertain area still exists, the above step 1
The processing after 20 is executed again. On the other hand, when it is determined that the peak spectra of all the regions have already been determined, this routine ends.

According to the above-mentioned processing, when an appropriate combination of peak spectra cannot be obtained by the frequency pairing method, the uncertain region is determined based on the spectrum analysis result of another region adjacent to the region. A part of the peak spectrum included in the spectrum analysis result can be accurately paired. When the number of uncertain peaks contained in the uncertain region decreases due to such pairing,
Compared to the case where all the peak spectra are uncertain peaks, the remaining peak spectra can be easily paired. Therefore, according to the system of the present embodiment, it is possible to easily and reliably pair a large number of peak spectra included in a plurality of spectrum analysis results. In this respect, the system of the present embodiment has an effect that it is possible to realize a function of accurately detecting an object in a wide detection area without incurring cost and responsiveness disadvantages.

In the above embodiment, the radar E
Of the radar signal processing unit 28 of the CU 10, the carrier wave generation circuit 32, the frequency modulation circuit 34, and the modulation voltage generation circuit 36.
For the frequency modulation mechanism, the mixer 40 and the amplification circuit 42 for the beat signal generation mechanism, the filter 44 and the FFT signal processing circuit 46 for the spectrum analysis mechanism, the scanning controller 16, the scanning mechanism 18, and the radar. The scanning angle control unit 26 of the ECU 10 corresponds to the above-mentioned scanning means. Further, in the above embodiment, the radar ECU 10 executes the steps 120 to 136.
The spectrum pairing means described above is realized by executing the processing of.

[0068]

As described above, according to the present invention, the upstream section spectrum and the downstream section spectrum are calculated for each scanning angle, and the data regarding the object is obtained for each scanning angle.
Therefore, it is possible to accurately detect the positions of the plurality of objects existing in the detection area wider than the irradiation range of the transmitted wave. Further, according to the present invention, the scanning angle data is used when the spectral peaks are paired. For this reason,
Spectral peaks can be easily paired as compared with the case where scan angle data is not used.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an FM-CW radar device that is an embodiment of the present invention.

FIG. 2 is a block diagram of a radar ECU used in the FM-CW radar device shown in FIG.

FIG. 3 is a block configuration diagram of a radar signal processing unit which is a component of the radar ECU shown in FIG.

FIG. 4A is a waveform showing a change in frequency of a signal transmitted and received by a radar antenna. FIG. 4B is a waveform of the peat signal detected by the radar ECU.

FIG. 5A is spectrum data representing an upstream frequency. FIG. 5B is spectrum data representing the downlink frequency.

6 is a diagram showing a detection range of the FM-CW radar device shown in FIG.

7 is a waveform showing the relationship between the scanning angle of the FM-CW radar device shown in FIG. 1 and the frequency of the transmitted wave.

8 is an object existing in front of the vehicle and the FM shown in FIG.
FIG. 6 is a diagram showing a scanning area of a CW radar device.

9A is an example of an upstream section spectrum obtained for the region shown in FIG. FIG. 9B is an example of the downlink section spectrum obtained for the region shown in FIG.

10A is an example of an upstream section spectrum obtained for the region shown in FIG. FIG.
(B) is an example of a downlink section spectrum obtained for the region shown in FIG. 8.

11A is an example of an upstream section spectrum obtained for the region shown in FIG. FIG.
(B) is an example of a downlink section spectrum obtained for the region shown in FIG. 8.

12A is an example of an upstream section spectrum obtained for the region shown in FIG. FIG.
(B) is an example of a downlink section spectrum obtained for the region shown in FIG. 8.

13 is a flowchart (No. 1) of an example of a control routine executed in a radar ECU included in the FM-CW radar device shown in FIG.

FIG. 14 is a flowchart (part 2) of an example of a control routine executed in the radar ECU included in the FM-CW radar device shown in FIG. 1.

[Explanation of symbols]

10 electronic control unit for radar (ECU for radar) 12 environment recognition vehicle speed control electronic control unit (ECU for environment recognition vehicle speed control) 14 radar antenna 16 scanning controller 18 scanning mechanism 26 scanning angle control unit 28 radar signal processing unit 30 object recognition unit 48 vehicle 50,52 object

Claims (1)

[Claims] 1. A frequency modulation mechanism for modulating the frequency of a transmitted wave at a predetermined rate of change, a beat signal generation mechanism for generating a beat signal based on a reflected wave and a transmitted wave with respect to the transmitted wave, and a beat signal. A spectrum analysis mechanism for detecting the spectrum intensity of each frequency component, and a spectrum analysis result about a beat signal obtained in the process of increasing the frequency of the transmission wave, and a beat obtained in the process of decreasing the frequency of the transmission wave. FM- which detects the distance to the object reflecting the transmitted wave and the relative speed of the object by combining with the spectrum analysis result of the signal.
In the CW radar, scanning means for scanning the transmission wave in a predetermined detection region, a peak spectrum included in a spectrum analysis result obtained in the process of increasing the frequency of the transmission wave, and a frequency of the transmission wave falling. An FM-CW radar device comprising: a spectrum pairing unit configured to pair a peak spectrum included in a spectrum analysis result obtained in the process based on scanning angle data of the scanning unit.