JPH0763842A - Relative-distance detecting apparatus - Google Patents

Abstract

PURPOSE:To make an operating speed and a detected speed compatible at a high level with regard to a relative-distance detecting apparatus for detecting the relative distances for a pluraity of obstacles indicating the different behaviors by using an FM-CW(freeuency-modulation continuous wave) radar. CONSTITUTION:An FM-CW radar 11, which transmits the modulating waves whose frequency periodically repeats rising and falling at the specified modulating width and detects the relative distance to obstacles based on the frequency difference fup between the transmitted wave and the reflected wave fdown in the frequency rising section of the modulating wave and the frequency difference in the frequency falling section, is provided. A camera 12, which photographs the obstacles, is provided. The approximate relative distance to the individual obstacle is obtained based on the picked-up image. Of a plurality of the frequency differences fup and the frequency differences fdown detected with the FM-CW radar 11, the set in conformity with the relative distance obtained by using the camera 12 is made to be a pair, and the basic data for the operation of the relative distance are obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relative distance detecting device, and more particularly to a relative distance detecting device suitable for accurately detecting the relative distance to each obstacle when a plurality of obstacles behave differently. Regarding

[0002]

2. Description of the Related Art As a device for measuring a relative distance between objects, an FM-CW (Frequency Modulation-Conti
A measurement device using a nuous wave radar is known.
This device transmits a modulated wave whose frequency repeatedly rises and falls with a predetermined modulation width, detects the frequency difference superimposed on the reflected wave of this modulated wave, and measures the relative distance between objects. It is a thing.

That is, if there is no relative velocity between the objects, it takes a propagation time according to the relative distance from the emission of the modulated wave to the return of the reflected wave. Therefore, a frequency difference between the frequency of the transmitted wave and the frequency of the received wave is determined by the frequency change rate of the modulated wave and the propagation time.

Here, the difference between the frequency of the transmitted wave and the frequency of the received wave when the frequency of the modulated wave is in the rising section is fup,
When the frequency difference in the falling section is fdown, fup = fdown holds if the frequency change rate is the same in the rising section and the falling section of the frequency except for the sign.

On the other hand, when there is a relative velocity between the objects, the reflected wave is superimposed with frequency fluctuation due to Doppler shift,
The frequency of the reflected wave is detected as high when the two are close to each other, and is low when the distance is far from each other. Therefore, the frequency difference fup in the ascending section is small, and the frequency difference fdown in the descending section is large, and they are detected as values shifted from the center frequency with substantially the same width according to the relative speed.

Therefore, fr = (fup + fdown) / 2, f
When the concept of d = (fup-fdown) / 2 is introduced,
The center frequency fr can be understood as a concept representing a relative distance, and the shift amount from the center frequency fd can be understood as a concept representing a relative speed.

That is, if the frequency difference fup when the frequency of the modulated wave is in the rising section and the frequency difference fdown when the frequency is in the falling section can be appropriately detected by using the FM-CW radar, these can be detected. It is possible to easily detect the relative distance and relative velocity between the objects from the values.

By the way, in the above conventional apparatus, FM-
When a plurality of obstacles exist in the monitoring area of the CW radar, the receiver receives the reflected waves corresponding to the respective obstacles. That is, when a plurality of obstacles exist in the monitoring area of the FM-CW radar, fup and f are the same number as the number of obstacles.
down will be detected.

Therefore, in such a case, f
It is necessary to perform pairing with up and fdown to calculate fr and fd corresponding to each obstacle. In this case, the simplest method is to pair fup and fdown in ascending order or in ascending order.

However, for example, one obstacle has no relative speed and fup = fdown (= f ₁ ) holds, and another obstacle at approximately the same distance has a relative speed, and fup <f ₁ When <fdown is established, it is obvious that pairing is performed in an incorrect combination by simply performing pairing in the order of size.

Japanese Unexamined Patent Publication (Kokai) No. 4-343084 discloses a device capable of improving such a point, which focuses on the intensity level of a reflected wave and pairs fup and fdown detected at the same level. ing. It is focused on that the intensity of the reflected wave received by the FM-CW radar differs depending on the shape and relative distance of the obstacle reflecting the modulated wave.

More specifically, the reflected wave received by the FM-CW radar is spectrum-analyzed in the rising section and the falling section to obtain fup and fdown, and those having similar spectral waveforms are paired. . According to such a configuration, correct pairing can be performed with significantly higher accuracy than in the case where pairing is simply performed based on the magnitudes of fup and fdown.

[0013]

However, even when the method of combining the ones having similar spectral waveforms as in the above-mentioned conventional apparatus is used, a plurality of obstacles having similar shapes to the spectral waveforms are detected. May not be able to perform pairing with the correct combination.

Then, in order to execute such processing,
It is necessary to extract and compare features of the same number of sets of spectral waveforms as the number of detected obstacles, and there is a drawback that the response speed becomes slow because complicated arithmetic processing is executed.

The present invention has been made in view of the above points, and detects a rough relative distance to an object to be detected by distance measuring means provided separately from the FM-CW radar, and the relative distance is detected. An object of the present invention is to provide a relative distance detecting device that can solve the above-mentioned problems by pairing a plurality of fup and fdown detected by an FM-CW radar as a reference.

[0016]

FIG. 1 is a block diagram showing the principle of a relative distance detecting device for achieving the above object. That is, the above-mentioned object is to transmit a modulated wave whose frequency repeats rising and falling periodically with a predetermined modulation width from the modulated wave transmitting means 1 as shown in FIG. 1 and to reflect the modulated wave by the reflected wave receiving means 2. A detection result of the rising section spectrum detecting means 3 which receives a wave and detects the frequency difference between the transmitted wave and the received wave in the section where the frequency of the modulated wave rises, and the transmitted wave in the section where the frequency of the modulated wave falls. In a relative distance detecting device including an FM-CW radar, which detects a relative distance to an obstacle that reflects the modulated wave, based on a detection result of the descending section spectrum detecting means 4 that detects a frequency difference between received waves, Distance measuring means 5 provided to detect the relative distance to the obstacle separately from the FM-CW radar, and the spectrum detected by the rising zone spectrum detecting means 3 as a frequency difference. When, in the spectrum of the falling section spectrum detecting means 4 detects a frequency difference, the distance measuring means 5
Spectrum combining means 6 which is used as basic data for calculating a relative distance for each obstacle by combining pairs that match the relative distance detected for each obstacle.
And a relative distance detecting device including

In the relative distance detecting device having the above structure, the number of spectra of the frequency difference detected by the ascending section spectrum detecting means 3 and the descending section spectrum detecting means 4 is equal to the number of obstacles detected by the distance measuring means 5. If it exceeds, the spectrum combination means 6 performs spectrum combination without considering the detection result of the distance measurement means 5 as long as the spectrum exceeds the number of obstacles detected by the distance measurement means 5. This is effective in achieving both high calculation speed.

[0018]

In the relative distance detecting device according to the present invention, by comparing the frequency of the modulated wave transmitted by the modulated wave transmitting means 1 with the frequency of the reflected wave received by the reflected wave receiving means 2, the rising section The spectrum detecting means 3 detects the Doppler shift spectrum fup when the modulating wave frequency is in the rising section, and the falling section spectrum detecting section 4 detects the Doppler shift spectrum fdown when the modulating wave frequency is in the falling section.

At this time, since a rough relative distance to the object to be detected is detected by the distance measuring means 5, it is possible to roughly back-calculate fup and fdown for each obstacle, and the spectrum combination described above. Means 6 are fup and fdo
The rough value of wn is obtained by back-calculation, and the actually calculated fup and fdown are combined together to improve the combination accuracy.

[0020]

FIG. 2 is a block diagram showing the overall construction of a relative distance detecting apparatus 10 which is an embodiment of the present invention.
The relative distance detecting device 10 of this embodiment is mounted on a vehicle and is configured to detect a relative distance and a relative speed to an obstacle ahead.

The FM-CW radar 11 shown in the figure corresponds to the modulated wave transmitting means 1, the reflected wave receiving means 2, the ascending section spectrum detecting means 3 and the descending section spectrum detecting means 4, and is modulated as described later. It is a device that emits a wave and generates a signal according to a relative distance and a relative speed to an object to be detected.

The camera 12 corresponds to the distance measuring means 5 described above, and a CCD type camera is used in this embodiment.
The camera 12 is provided to monitor the front of the vehicle and roughly measure the relative distance and the relative speed to the front obstacle, and is a main part of the relative distance detection device 10.

As a method of measuring the distance using the image picked up by the camera, a method of performing triangulation using cameras arranged at two different points is known. Therefore, when the distance measuring means 5 is realized by such a method, two CCDs are used.
It is necessary to configure the camera 12 using a camera.

As a method of measuring the relative distance with one camera, for example, a vertical edge (a portion where the brightness changes) in a captured image including a vehicle in front is detected and detected near the lower end of the image. A known method is to obtain the Y coordinate value of the edge at the boundary between the road surface and the vehicle, and obtain the relative distance from the Y coordinate value. Therefore, when the distance measuring means 5 is realized by such a method, the camera 12 can be realized by one CCD camera.

The control device 13 calculates the relative distance and relative speed to the obstacle ahead of the vehicle according to the relative distance signals supplied from the FM-CW radar 11 and the camera 12, and detects the risk of a rear-end collision. The alarm device 14 informs the driver of the situation, or the brake mechanism 15
Is a device that performs processing such as activating the to avoid a collision.

The control device 13 is the FM-CW radar 1
1 and an input port 1 incorporating an A / D converter for digitizing analog signals supplied from the camera 12
6, an output port 17 incorporating a drive device for appropriately driving the alarm device 14 and the brake mechanism 15, and a central processing unit (C) which is mutually connected to these via a common bus 18.
PU) 19, read only memory (ROM) 20, and random access memory (RAM) 21, which realizes the spectrum combining means 6 by the CPU 19 executing a program stored in the ROM 20. Is.

Hereinafter, the control device 13 which is an essential part of this embodiment.
However, the processing executed to realize the spectrum combination means 6 will be described in detail. Prior to that, FM-
The configuration of the CW radar 11 and the principle of detecting the relative distance by the FM-CW radar 11 will be described.

FIG. 3 shows a block diagram of the FM-CW radar 11. As shown in the figure, the FM-CW radar 11
The transmitting side circuit includes a carrier wave generator 22 and a frequency modulator 2.
3, a modulation voltage generator 24, a circulator 25, and a transmission antenna 26. A triangular wave whose amplitude changes in a triangular shape is output from the modulation voltage generator 24, and is supplied to the frequency modulator 23 as a modulation wave.

As a result, the carrier wave from the carrier wave generator 22 is frequency-modulated, and as shown by the solid line in FIG. 4 (A), with a predetermined fluctuation width Δf and modulation frequency fm (= 1 / T) over time. A modulated wave signal whose frequency is modulated in a triangular shape is output. Then, the modulated wave signal is supplied to the transmitting antenna 26 via the circulator 25, is emitted toward the obstacle as the detected object, and is also supplied to the mixer 28 of the receiving side circuit described later. The above-mentioned transmission side circuit corresponds to the above-mentioned modulated wave transmitting means 1.

The receiving side circuit includes a receiving antenna 27, a mixer 28, an amplifier 29, an anti-aliasing filter 30,
And a fast Fourier transform processor (FFT signal processor) 31 realized by the control circuit 13. That is, the modulated wave transmitted from the transmitting antenna 26 is reflected by an obstacle and received by the receiving antenna 27, and the mixer 2
8 are supplied.

The waveform indicated by the dotted line in FIG. 4 (A) shows how the frequency of the reflected wave received by the receiving antenna 27 changes. In the mixer 28, the signal representing the state of the reflected wave and the signal representing the state of the transmitted wave supplied from the circulator 25 are combined by a difference calculation to generate a beat signal that fluctuates at a frequency according to the frequency difference between the two. It FIG. 4B shows the frequency fluctuation situation of the beat signal, where the frequency in the frequency rising section of the triangular modulation wave is fup,
The frequency in the frequency falling section is represented as fdown.

The beat signal from the mixer 28 is supplied to the amplifier 2
It is amplified by 9 and supplied to the anti-aliasing filter 30. The beat signal supplied to the anti-aliasing filter 30 is separated into a beat signal in the rising section and a beat signal in the falling section here, and then input to the FFT signal processor 31. Then, the FFT signal processor 31
Performs FFT processing on the beat signal in each section, and f
Calculate the power spectrum for up and fdown.

FIG. 5 shows the power spectrum of the FFT signal processor 31 in the case where two obstacles are present in front of the vehicle, showing an ascending section (FIG. 5A) and a descending section (FIG. 5).
(B)). That is, when there are, for example, two obstacles in front of the vehicle, the reception antenna 27 receives the reflected waves of the respective obstacles.
Therefore, the beat signals representing the frequency difference between the transmitted wave and the received wave are formed by the number corresponding to each obstacle, and as a result, F
The power spectrum output from the FT signal processor 31 has two peaks.

By the way, assuming that there is no relative velocity between the vehicle and the obstacle ahead, the modulated wave transmitted from the transmitting antenna 26 is required for the modulated wave to reach the obstacle and then to be reflected and returned. Receiving antenna 27 after time passes
To reach. In this case, the Doppler shift is not superimposed on the frequency of the reflected wave, and if the situation is shown in FIG. 4 (A), the waveform showing the frequency fluctuation of the reflected wave will move the transmitted wave in parallel in time. The waveform becomes

Then, the frequency of the beat signal in the rising section is fup, and the frequency of the beat signal in the falling section is fup.
If it is down, in this case, fup = fdown holds, as described above, and the magnitude of fup (= fdown) has a value corresponding to the relative distance between the vehicle and the obstacle.

On the other hand, when the relative velocity v exists between the vehicle and the obstacle, the reflected wave is superposed with the Doppler shift corresponding to the relative velocity. Then, for example, if the two are close to each other, the frequency of the reflected wave shifts to the high frequency side as a whole, and the waveform showing the frequency fluctuation of the reflected wave changes according to the relative distance, as shown in FIG. Thus, the waveform obtained by translating the transmitted wave in parallel with respect to time becomes a waveform obtained by further translating to the high frequency side.

That is, as compared with the case where there is no relative speed, fup
Is small and fdown is large, and each changes by an amount according to the magnitude of the relative speed. Therefore, if the concept of fr = (fup + fdown) / 2 (1) is introduced, the Doppler shift component is canceled out, resulting in a characteristic value representing the relative distance, and fd = (fup-fdown) / Introducing the concept of 2 ... (2), the magnitude of the Doppler shift is obtained, and the characteristic value representing the relative speed is obtained.

The center frequency of the modulated wave is f ₀ , the modulation frequency is fm, the modulation width is Δf, the relative velocity is v, and the relative distance is L.
Then, the theoretical values of fr and fd with respect to the speed of light c are as follows.

Fr = 4fm · Δf · L / c (3) fd = 2v · f ₀ / c (4) Therefore, in the case where two spectrum peaks are obtained as shown in FIG. , FMu1 and FMd1 are a pair,
If FMu2 and FMd2 are a pair, fr = (FMu
1 + FMd1) / 2, fd = (FMu1-FMd1) / 2, the relative distance L and the relative speed v for one obstacle
Then, the relative distance L and the relative velocity v can be obtained by performing similar processing on the other.

By the way, in the above calculation example, FMu1 and FMd1
And are paired, and FMu2 and FMd2 are paired. However, the spectra for the same obstacle do not always appear in the same order in the rising section and the falling section. Further, regarding a plurality of vehicles, a plurality of motorcycles, and the like, the intensity of the reflected wave, that is, the spectral waveform is also approximated. Therefore, it is not universal to appropriately combine the similar spectral waveforms.

As described above, when the FM-CW radar 11 detects a plurality of obstacles, the process of appropriately combining the spectrum of the ascending section and the spectrum of the descending section is not always an easy process, and the processing speed is higher than that in the past. It has been said that it is difficult to maintain the appropriate level of accuracy and ensure an appropriate combination accuracy.

The relative distance detecting apparatus 10 of the present embodiment surely executes the above combination processing by a simple processing by using the relative distance auxiliary detected by the camera 12, and FM
The feature is that relative distance detection can be performed by making use of the high detection accuracy of the CW radar 11.
Hereinafter, the contents of the combination processing executed by the control device 13 will be described in detail with reference to the flowchart shown in FIG.

When the process shown in the figure is started, first in step 1 (hereinafter referred to as S1), the number i of obstacles in front of the vehicle is set to Nn based on the image data captured by the camera 12, and the rough relative to each obstacle is obtained. The distance is calculated as Ln (n = 1 to i), and the relative speed for each obstacle is calculated as RVn (n = 1 to i). In this case, L
n can be calculated by triangulation using two CCD cameras as described above, or calculation of the Y coordinate value of the lower edge of the detected image of the preceding vehicle, and for RVn, the temporal change rate of Ln can be calculated. The calculation can be performed by obtaining it.

After the rough data for the obstacle is calculated from the image data picked up by the camera 12 in this way, the FM-CW radar 11 advances to S2 to execute highly accurate detection, and the FFT signal processor 31 is operated. Perform the corresponding processing. That is, the rising section spectrum and the falling section spectrum are detected from the beat signal obtained by the FM-CW radar 11. Thus, in the present embodiment, S2 corresponds to the rising section spectrum detecting means 3 and the falling section spectrum detecting means 4 described above.

In step S3, the result of spectrum analysis by the FFT process is stored in the RAM 21, and the frequency data of the ascending section spectrum is sequentially added to FMum (m = 1 to j) from the smallest (or from the largest) to the descending. The frequency data of the section spectrum is stored in FMdm (m = 1 to j) in order from the smallest (or from the largest), and these number data j are stored in Nm.

By the way, as described above, FMum and FMdm
By properly combining and, fr = (FMum + FMdm)
Fr, which represents the relative distance according to / 2, is also fd = (FM
fd representing a relative distance can be calculated according to um-FMdm) / 2. On the other hand, if Ln is found in S1, then Ln
It is possible to back-calculate the calculated value FCrn of fr for each obstacle based on n, and also to calculate the calculated value FCdn of fd from RVn.

Step S4 is a step for performing such a back calculation, and FCrn (n = 1 to i) is used as the calculated value of fr, fd
FCdn (n = 1 to i) as the calculated value of Ln,
Calculate based on RVn.

The following S5 is the calculation of these calculated values FCrn and F.
The calculated value FC1n of FMum and the calculated value F of FMdm are calculated using Cdn.
This is the step of obtaining C2n. Since the sum of FCrn and FCdn is the calculated value FC1n of FMum and the difference between FCrn and FCdn is the calculated value FC2n of FMdm, the calculated value of FMum and FMdm for each obstacle can be calculated by the camera 12 It is calculated back based on the imaged image data of.

Therefore, FMum obtained in S3,
If FMdms detected near FC1n and FC2n, respectively, are paired, it is ensured that the combined FMum and FMdm are spectra related to an obstacle imaged by the camera 12. As a result, incorrect pairing is effectively prevented.

In view of this point, the processing after S6 is performed only when it is ensured that the pair is normal.
It is for pairing with dm. That is, when the various counters k, m, and n are initialized to "1" in S6, S
7. First, it is determined whether the first spectral peak FMu1 in the rising section exists within ± ΔFe of FC11. When FC11−ΔFe <FMu1 <FC11 + ΔFe is satisfied, the process proceeds to S8, and similarly, it is determined whether the first spectrum peak FMd1 in the descending section exists within ± ΔFe of FC21. Here, ΔFe is a judgment tolerance introduced in consideration of various detection errors and the like.

Both the conditions of S7 and S8 are satisfied when FMu1 and FMd1 are formed by the reflected waves reflected by the same obstacle, and in this case, both should be treated as a pair. Therefore, if both conditions are satisfied in S7 and S8, the process proceeds to S9, and FMu1 and FMd1 are substituted into fup and fdown in the above equations (1) and (2), and the results are (3) and (4). The relative distance L and the relative speed v are calculated by substituting into the formula. Then, the result is stored as XL1 and XRV1, and k is incremented in S10 to indicate that the collation is completed for one set of spectra.

On the other hand, it is determined that the condition is not satisfied in any one of S7 and S8, that the spectrum of the obstacle different from the obstacle captured by the camera 12 in the ascending section or the descending section is collated. This is the case when it is targeted. Therefore, in this case, FMu1 and FMd1 should not be combined, and collation is not possible, and the process proceeds to S11.

In step S11, the counters m and n are incremented. In the subsequent steps S12 and S13, it is determined whether n≤Nn and m> Nm, respectively. That is, S12
Is a step of checking whether or not the number of pieces of data for which the collation inspection has been completed has reached the number Nn (= i) of obstacles detected by the camera 12, and S13 is the number of pieces of data for which the collation inspection has been performed FM- This is a step of checking whether or not the number Nm (= j) of spectra detected by the CW radar 11 has been reached.

In order to carry out S7 and S8, it is premised that the data from the camera 12 and the data from the FM-CW radar 11 both exist, and the camera 1
2 and FM-CW radar 11, the fact that Nn and Nm are not always the same due to the difference in the detection capability and the detectable area is taken into consideration. When the number of detected data of one exceeds the number of detected data of the other. Is provided by adopting a configuration in which the relative distance L and the relative velocity v are calculated by different methods.

Therefore, while it is determined in S12 that n ≦ Nn and m> Nm is not satisfied in S13, the processes of S7 to S13 are repeatedly executed. When an appropriate pair is established for FMum and FMdm, the relative distance L and the relative velocity v are sequentially calculated based on them, and the calculation result is XLk, XR.
It is stored as Vk.

On the other hand, when it is determined that n≤Nn is not satisfied as a result of incrementing m and n in S11, that is, the number of spectra already detected by the camera 12 is the same as the number Nn of spectrums detected by the camera 12. If the collation inspection for the set has already been performed, the above S7 and S8 cannot be performed thereafter, and thus the remaining FM
-Proceed to S20 to calculate the relative distance L to the obstacle and the relative speed v based only on the detection data of the CW radar 11.

Then, if FMum and FMdm are further present for m incremented in S11, S20
At FM, the relative distance L calculated from FMdm and the relative speed v are stored as XLk and XRVk, respectively, and then m and k are incremented at S21, and then it is checked at S22 whether m> Nm holds.

After that, the above steps S20 to S22 are repeatedly executed until m> Nm is satisfied, that is, until it is determined that the pairing is completed for all the spectra detected by the FM-CW radar 11.

Regarding the method of pairing the spectrum of the rising section and the spectrum of the falling section in S20, in addition to the method of sequentially pairing FMum and FMdm in accordance with m incremented as described above, You may use the method of pairing the spectra which approximate.

Further, before n ≦ Nn is not satisfied, S13
When it is determined that m> Nm is satisfied, that is, all spectra F detected by the FM-CW radar 11 are detected.
When the detection data of the camera 12 remains despite the completion of the collation inspection for Mum and FMdm (m = 1 to j), the relative distance to the obstacle is determined only by the detection data of the remaining camera 12. It is necessary to calculate L and relative velocity v. Therefore, if such a determination is made, the process proceeds to S14 thereafter, and the detected data values Ln, RVn of the camera 12 are detected.
Are stored as they are as relative distance XLk and relative velocity XRVk.

Then, n and k are incremented in S15, and Ln and RVn are set to a relative distance L and a relative speed v until n> Nn is established in S16 for the n.
Are directly stored as XLk and XRVk.

Thus all spectra FMum,
Based on FMdm (m = 1 to Nm = j) and all detection data Ln and RVn (n = 1 to Nn = i) by the camera 12, the relative distance L and the relative velocity v are XLk and XRV.
If it is stored as k, the process proceeds to S17, the calculation result is output, and the process of this time is ended.

As a result, the ascending section spectrum FMum and the descending section spectrum FMdm detected by the FM-CW radar 11 will be recognized as a pair only when they are true to each other, and FMum and FMdm are recognized as a pair. No incorrect relative distance and relative velocity are calculated by improper combination.

Further, the FM-CW transmitter 11 and the camera 12
When one of the obstacles detects a larger number of obstacles than the other due to a difference in detection accuracy and a detectable area from
Since the detection result of the radar is supplemented by the camera 12 and the data exceeding the coexistence portion is subjected to the arithmetic processing using the data of the FM-CW radar 11 or the camera 12 independently, a high detection accuracy can always be maintained.

Further, the relative distance detecting apparatus of the present embodiment can extremely easily and surely pair the ascending section spectrum FMum and the descending section spectrum FMdm when the detection data of the camera 12 can be used. Therefore, there is also an effect that the same or more processing can be executed at an extremely short calculation speed as compared with, for example, a device for pairing those that approximate all spectral waveforms by using only the FM-CW radar 11. ing.

Note that, in the routine shown in FIG. 6, when it is recognized that the ascending section spectrum FMum and the descending section spectrum FMdm should not be paired in order to simplify the software configuration, the routine determines the FMum and FMdm. Instead of using the configuration, the configuration entrusted to the routines from the next time onward is adopted. However, the configuration is not limited to this, and a configuration may be made in which a pair is created for all the detected FMum and FMdm for each routine.

[0067]

As described above, according to the first aspect of the present invention, the ascending section spectrum fup and the descending section spectrum fdown detected by using the FM-CW radar can be appropriately combined, and the combination thereof can be obtained. Since the processing is performed on the basis of the detection result of the distance measuring means, it has a feature that the relative distance and relative speed for each obstacle can be calculated at an appropriate calculation speed.

According to the second aspect of the invention, the FM
-When the CW radar detects a large number of objects compared to the distance measuring means, fup and fdown detected by the ascending section spectrum detecting means and the descending section spectrum detecting means are combined by the method according to claim 1 at the maximum, Remaining fup, f
Since it suffices to execute the combination processing in accordance with the characteristics of the spectrum only for down, the combination processing of fup and fdown can be executed while making the combination accuracy and the calculation speed compatible at an appropriate level. .

[Brief description of drawings]

FIG. 1 is a principle diagram of a relative distance detecting device according to the present invention.

FIG. 2 is a block configuration diagram showing an overall configuration of a relative distance detection device that is an embodiment of the present invention.

FIG. 3 is a block configuration diagram of an FM-CW radar of the relative distance detection device of this embodiment.

FIG. 4 is a diagram for explaining a principle of measuring a relative distance and a relative velocity by an FM-CW radar.

FIG. 5 is an example of an ascending section spectrum and a descending section spectrum detected by an FM-CW radar.

FIG. 6 is an example of a flowchart of a routine process executed by the control device of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Modulated wave transmission means 2 Reflected wave reception means 3 Ascending section spectrum detecting means 4 Falling section spectrum detecting means 5 Distance measuring means 6 Spectrum combining means 11 FM-CW radar 12 Camera 13 Control device

Claims (2)

[Claims] 1. A modulated wave transmitting means transmits a modulated wave whose frequency repeatedly rises and falls with a predetermined modulation width, and a reflected wave receiving means receives the reflected wave of the modulated wave.
The detection result of the rising section spectrum detecting means for detecting the frequency difference between the transmitted wave and the received wave in the section where the frequency of the modulated wave rises, and the frequency difference between the transmitted wave and the received wave in the section where the frequency of the modulated wave falls. A relative distance detection device including an FM-CW radar that detects a relative distance to an obstacle that reflects the modulated wave based on a detection result of a descending section spectrum detection unit that is detected, the FM-CW radar being separate from the FM-CW radar. Distance measuring means provided to detect a relative distance to an obstacle, a spectrum detected by the rising zone spectrum detecting means as a frequency difference, and a spectrum detected by the falling zone spectrum detecting means as a frequency difference, A pair of pairs that match the relative distances detected by the distance measuring means for the individual obstacles is combined to determine the relative distances for the individual obstacles. Relative distance detecting device, characterized in that it comprises a spectrum combining means to basic data at the time of calculation. 2. The relative distance detecting device according to claim 1, wherein the number of spectra of the frequency difference detected by the ascending section spectrum detecting means and the descending section spectrum detecting means exceeds the number of obstacles detected by the distance measuring means. In this case, the spectrum combining means performs spectrum combination only for spectra exceeding the number of obstacles detected by the distance measuring means without considering the detection result of the distance measuring means.