JPH07128440A - Radar equipment - Google Patents

Abstract

PURPOSE:To improve the accuracy in detection by a method wherein the frequency at the level cetroid of a spectral distribution within a frequency width through the front and the rear of a maximal spectrum at every unit frequency interval of a beat signal is made to be a relative distance of an object. CONSTITUTION:As to a traansmission signal generated by an oscillator 1, an electromagnetic wave beam B is transmitted from an antenna 3 through a modulation control circuit 2 and others. A reflected wave from an object is inputted to a mixer 7 through a circulator 6. The mixer 7 executes mixing of the transmission signal from the oscillator 1 with the reception signal. In the case where two objects A1 and A2 are present in the direction of transmission of the beam, the spectral distribution of a bet signal is a distribution wherein a spectral level takes a maximal value at a frequency corresponding to each of relative distnces D1 and D2 of the objects A1 and A2. The beat signal generated by the mixer 7 is subjected to A/D conversion and stored and held in a time series in a memory 10. A signal processing device 12 determines the relative distances D1 and D2 on the basis of the data stored and held in the memory 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device for detecting the position of an object.

[0002]

2. Description of the Related Art In recent years, for example, in an automobile, the relative distance of an object (obstacle) such as another vehicle existing in front of or behind the own vehicle to the own vehicle, and further, the relative position including the direction of the own vehicle is determined. A device has been developed which is detected by using a radar device mounted on a vehicle and holds an appropriate inter-vehicle distance according to the detection, performs automatic traveling control such as braking, and performs various alarms. And, in this type of radar device, it is relatively easy to simplify the system configuration, and
An FM-CW radar device is generally used for the reason that it is possible to detect an object located at a short distance from the own vehicle.

This FM-CW radar device transmits an electromagnetic wave beam that has been modulated so that the frequency increases and decreases at an appropriate cycle, and at the same time transmits a reflected wave from an object existing in the transmitting direction of the electromagnetic wave beam. At this time, the frequency of the beat signal, which is received by the antenna and is obtained by mixing a part of the transmitted signal and the received signal in the radar device, is caused by the propagation delay of the received signal and the transmission of the electromagnetic wave beam. By utilizing the fact that it is proportional to the relative distance of the object in the wave direction and by detecting the frequency of the beat signal, the relative distance to the object in the wave transmission direction of the electromagnetic wave beam is detected.

Further, for example, in an FM-CW radar device for an automobile, an electromagnetic wave beam is transmitted from one antenna or two antennas in two different directions adjacent to each other with a time difference, and both electromagnetic wave beams are transmitted. Relative to the target object from the frequency of the beat signal, which is the reflected wave from the target object such as another vehicle existing in the wave direction, is received for each electromagnetic wave beam, and the received signal and the transmitted signal are mixed respectively. While detecting the distance, the reception level of the reflected wave corresponding to each electromagnetic beam, that is, the ratio of the sum and difference of the spectrum level of the frequency corresponding to the relative distance of the object in the transmission direction of each electromagnetic beam It is also known that the direction of the object with respect to the own vehicle is detected from the value, and thereby the two-dimensional relative position of the object with respect to the own vehicle is detected. That (for example, see JP-A-5-87914 filed by the present applicant).

By the way, in such an FM-CW radar device, in general, the beat signal has a frequency component corresponding to a received signal of a direct reflected wave from the object (this corresponds to the relative distance of the object. Frequency components other than) are also included. Further, when there are a plurality of objects having different relative distances in the transmission direction of the electromagnetic wave beam, frequency components corresponding to the relative distances of these respective objects are mixed. For example, when two objects exist in the transmission direction of the electromagnetic wave beam, the spectral distribution (frequency distribution) of the beat signal has relative distances D ₁ and D ₁ of the respective objects as shown by phantom lines in FIG. Frequencies f ₁ , f corresponding to _{2
At 2} , the distribution is mountainous so that the spectrum level has a maximum value.

Therefore, when detecting the relative distance of the object by the frequency of the beat signal, the beat signal is frequency-analyzed to obtain its spectral distribution, and the spectral level is determined from the spectral distribution to a local maximum of an appropriate level or more. It is desirable to detect a frequency having a value and obtain the relative distance of the object by the detected frequency. If the spectrum distribution of the beat signal is obtained in this way, the frequency corresponding to the relative distance of the object can be detected with relatively high accuracy from the spectrum distribution, and a plurality of objects can be detected in the transmission direction of the electromagnetic beam. Even if it exists, the relative distance of each object can be detected.

On the other hand, the frequency analysis of the beat signal can be carried out by using a plurality of bandpass filters or an arithmetic processing method such as FFT (fast Fourier transform method).
In either method, it is not possible to obtain a continuous spectrum distribution in the frequency direction, and only a discrete spectrum distribution for each unit frequency interval corresponding to the frequency resolution of these methods can be obtained. That is, as shown by the solid line in FIG. 3, when the beat signal is frequency-analyzed by FFT or the like, discrete spectrum data is obtained for each unit frequency interval Δf. Then, when detecting the frequency corresponding to the relative distance of the object based on such discrete spectrum data, it is general to simply detect the spectrum in which the spectrum level has a maximum value. However, when the frequency corresponding to the original relative distance of the object is between adjacent spectra, the detected frequency is different from the frequency corresponding to the original relative distance of the object, and therefore, The detection accuracy of the relative distance of the object will be reduced.

In order to eliminate such an inconvenience, it is sufficient to increase the frequency resolution in the frequency analysis of the beat signal and reduce the unit frequency interval. However, if the frequency resolution is increased in this way, the beat signal is required. The number of sampling data increases, the processing time for frequency analysis becomes longer, and the processing time for detecting the spectrum in which the spectrum data also increases and the spectrum level becomes the maximum value becomes longer. It becomes impossible to detect the relative distance of the object quickly.

Further, in the case of detecting not only the relative distance of an object but also its azimuth, conventionally, as described above, the sum of the spectrum levels obtained corresponding to the relative distance of the object in each of the two electromagnetic waves and Although the orientation of the target object is obtained from the ratio to the difference, in this type, if the directivity of the two electromagnetic waves is increased, the detection accuracy of the relative position of the target object can be improved to some extent. Although possible, this would narrow the detection range of the object. On the contrary, if the directivity of the electromagnetic wave beam is reduced, the detection accuracy of the relative position of the object is significantly reduced. Then, it is difficult to detect the relative position of the object with high accuracy because it is easily affected by the movement of the object and the like.

[0010]

In view of the background described above, the present invention seeks a spectral distribution of a beat signal formed by mixing a transmission signal of an electromagnetic wave beam and a reception signal from an object,
When electricity detects the relative distance of an object in the beam transmission direction from the spectral distribution, the radar can accurately detect the relative distance of the object from the spectral distribution without increasing the frequency resolution of the spectral distribution. The purpose is to provide a device.

Further, when a relative position of an object is detected by using a plurality of electromagnetic waves whose transmission directions are different from each other, the radar device can detect the relative position of the object with high accuracy. The purpose is to provide.

[0012]

In order to achieve the above-mentioned object, a first aspect of the present invention is to provide a transmitting means for transmitting an electromagnetic wave whose frequency is temporally modulated, and a transmitting direction of the electromagnetic wave. Receiving means for receiving a reflected wave from an object existing in
Beat signal generating means for generating a beat signal having a frequency corresponding to the relative distance of the object by mixing a part of the transmitted wave signal of the electromagnetic wave and the received wave signal of the reflected wave; Frequency analysis means for analyzing and obtaining a spectrum distribution for each predetermined unit frequency interval of the beat signal, and maximum spectrum detection means for obtaining the frequency of the maximum spectrum at which the spectrum level has a maximum value of a predetermined level or more from the spectrum distribution A level center of gravity detecting means for obtaining a frequency of a level center of gravity of the spectral distribution within a predetermined frequency range extending before and after the frequency of the maximum spectrum, and the frequency of the level center of gravity as the frequency corresponding to the relative distance of the object. And a distance detecting means for obtaining a relative distance of the object.

The level center of gravity detecting means obtains a sum of values obtained by multiplying the frequency of each spectrum of the spectrum distribution within a predetermined frequency width extending before and after the frequency of the maximum spectrum by the level of the spectrum, The frequency of the level center of gravity is obtained by dividing the obtained total sum by the total sum of the levels of each spectrum within the frequency width.

In order to achieve the above-mentioned object, the second aspect of the present invention is to provide a transmitting means for transmitting an electromagnetic wave beam whose frequency is temporally modulated in a plurality of directions adjacent to each other, and the electromagnetic wave. Receiving means for receiving, for each electromagnetic wave beam, a reflected wave from an object existing in the beam transmitting direction, a part of a transmitted signal of each electromagnetic beam, and a received signal of the reflected wave corresponding thereto And beat signal generating means for generating a beat signal having a frequency corresponding to the relative distance of the object in the transmission direction of each electromagnetic beam, and frequency analysis of the beat signal corresponding to each electromagnetic beam. Frequency analysis means for obtaining the spectrum distribution of the beat signal, and the spectrum frequency corresponding to the relative distance in the transmission direction of each electromagnetic wave beam of the object is obtained from the spectrum distribution of each beat signal. Object frequency detecting means, distance detecting means for obtaining the relative distance of the object in the transmission direction of each electromagnetic beam from the object frequency, and each electromagnetic wave for which the relative distance of the object is obtained by the distance detecting means The position of the two-dimensional level barycenter of the spectral level of the object frequency corresponding to the pair of the relative distance of the object and the transmission direction of the electromagnetic wave beam with respect to the beam is calculated,
Level center of gravity detection means for obtaining the position of the dimensional level center of gravity as a two-dimensional relative position of the object.

Then, the level center of gravity detecting means determines a position of the electromagnetic wave for which the relative distance of the object has been determined by a relative distance of the object for each electromagnetic beam and a transmission direction of the electromagnetic beam. A two-dimensional coordinate component is multiplied by a spectrum level of the object frequency corresponding to the position to obtain a sum of values for each coordinate component, and the obtained sum is obtained for each coordinate component. By dividing by the sum of
It is characterized in that the coordinate component of the position of the two-dimensional level barycenter is obtained.

[0016]

According to the first aspect of the present invention, the maximum spectrum in the discrete spectral distribution of the beat signal for each unit frequency interval is substantially near the frequency corresponding to the actual relative distance of the object. Although present in the region, the frequency of the maximum spectrum and the frequency corresponding to the actual relative distance of the object do not always match. This is because the frequency corresponding to the actual relative distance of the object is such that, if a continuous spectrum distribution is obtained in the frequency direction of the beat signal, the spectrum level of the continuous spectrum distribution becomes a maximum value. This is because the maximum spectrum is the frequency of the maximum spectrum in the discrete spectrum distribution of the beat signal for each unit frequency interval. The frequency of the level centroid of the discrete spectral distribution within the predetermined frequency width extending before and after the frequency of the maximum spectrum is such that the spectrum level has a maximum value (maximum value) within the frequency width. Is estimated based on each discrete spectrum within the frequency width, which is generally a value closer to the frequency corresponding to the actual relative distance of the object. Therefore, by obtaining the relative distance by using the frequency of the level center of gravity as a frequency corresponding to the relative distance of the object, it is possible to improve the accuracy of the obtained relative distance.

As for the frequency of the level centroid, the sum of values obtained by multiplying the frequency of each spectrum of the spectrum distribution within the predetermined frequency width by the level of the spectrum is calculated, and the calculated sum is calculated as the frequency. It can be obtained by dividing by the sum of the levels of each spectrum within the width.

Next, according to the second aspect of the present invention, the spectral level of the object frequency obtained for each electromagnetic beam corresponding to the relative distance of the object in the transmitting direction of each electromagnetic beam. Corresponds to the wave receiving level of the reflected wave directly received by the wave receiving means among the reflected waves of each electromagnetic beam from the object, and generally, the transmitting direction of the electromagnetic wave and the direction of the object. When and match, the maximum level is obtained at the frequency corresponding to the relative distance of the object in that direction. On the other hand, the spectrum level of the object frequency is determined by the relative distance obtained by the object frequency and the transmission direction of the electromagnetic wave for which the relative distance is obtained 2.
The position of the two-dimensional level center of gravity of the spectral level of the object frequency can be obtained for each electromagnetic wave beam corresponding to the dimensional relative position and thus the object frequency is obtained. Then, the two-dimensional level center of gravity is for estimating a two-dimensional relative position such that the spectrum level corresponding to the wave receiving level of the reflected wave directly received by the wave receiving means becomes maximum. Therefore, by obtaining the position of the two-dimensional level barycenter as the relative position of the object, the relative position of the object can be obtained with high accuracy.

The position of the center of gravity of the two-dimensional level is determined by the relative distance of the object for each electromagnetic beam and the transmission direction of the electromagnetic beam for each electromagnetic beam for which the relative distance of the object is obtained. A two-dimensional coordinate component at a fixed position is multiplied by the spectral level of the object frequency corresponding to the position to obtain a sum of values for each coordinate component, and the obtained sum is obtained for each coordinate component of the object frequency. By dividing by the sum of the spectral levels of
The coordinate component of the position of the two-dimensional level barycenter can be obtained. In this case, the two-dimensional coordinate may use either a rectangular coordinate system or a polar coordinate system.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the first aspect of the present invention will be described with reference to FIGS. FIG. 1 is a system configuration diagram of the radar device of the present embodiment, FIGS. 2 and 3 are diagrams for explaining the operation of the radar device of FIG. 1, and FIGS. 4 and 5 are diagrams of the operation of the radar device of FIG. It is a flowchart for doing.

Referring to FIG. 1, the radar device according to the present embodiment is installed in, for example, an automobile, 1 is an oscillator for generating a transmission signal of an electromagnetic wave, and 2 is a transmission signal generated by an oscillator 1. A modulation control circuit that temporally modulates and controls the frequency,
3 transmits an electromagnetic wave beam B having the same frequency as the transmitted signal in a predetermined direction in accordance with the transmitted signal provided from the oscillator 1 through the isolator 4, the directional coupler 5 and the circulator 6. An antenna for receiving a reflected wave of the transmitted electromagnetic wave beam, 7 is a part of a transmitted signal distributed / input through the directional coupler 5 and a received wave input from the antenna 3 through the circulator 6. A mixer for mixing the signals with each other to generate a beat signal having a frequency corresponding to a temporal frequency difference between the two signals, an amplifier 8 for amplifying the beat signal generated by the mixer 7 to a required level,
9 is an A / D converter for A / D converting the beat signal amplified by the amplifier 8. 10 is A / D by the A / D converter 9.
A memory that stores the converted beat signal in time series according to the timing signal provided from the timing signal generation circuit 11 in synchronization with the modulation control circuit 2, and 12 stores the data of the beat signal stored and held in the memory 10. It is a signal processing device that performs a calculation process to obtain a relative distance of an object such as another vehicle existing in the transmission direction of the electromagnetic wave beam B to the own vehicle.

In these configurations, the oscillator 1, the modulation control circuit 2, the isolator 4, the directional coupler 5, the circulator 6 and the antenna 3 constitute the wave transmitting means 13, and the antenna 3 and the circulator 6 constitute the wave receiving means 14. Configure and
The mixer 7 constitutes the beat signal generation means 7. Also,
The signal processing device 12 is configured by an electronic circuit including a microcomputer and the like, and the functional components thereof include the frequency analysis means 15 and the maximum spectrum detection means 1.
6, a level center of gravity detecting means 17 and a distance detecting means 18 are provided.

Next, the operation of the radar system will be described together with a detailed description of each part thereof.

In the radar device of this embodiment, the oscillator 1
The frequency of the transmission signal generated by the signal is controlled by the modulation control circuit 2 as shown by the solid line in FIG. That is, the frequencies of the transmitted signals are the frequencies f _X and f _Y (f
It is modulated so as to increase / decrease cyclically between _X <f _Y ), in other words, in a triangular wave shape. Then, the transmission signal whose frequency is modulated and controlled in this way passes through the isolator 4, the directional coupler 5 and the circulator 6 to the antenna 3
Then, the electromagnetic wave beam B having the same frequency as the transmitted signal is transmitted from the antenna 3. At this time, the electromagnetic wave beam B has directivity and is transmitted, for example, toward the front of the vehicle.

When the electromagnetic wave beam B is transmitted, as shown in FIG. 1, when an object A such as another vehicle is present in the direction of the wave transmission, the electromagnetic wave beam B is reflected by the object A and is reflected. The wave is received by the antenna 3. The received signal of the reflected wave is input to the mixer 7 via the circulator 6. In addition, a part of the transmission signal output from the oscillator 1 is distributed and input to the mixer 7 through the directional coupler 5, and the mixer 7 transmits the transmission signal and the reception signal. To mix.

Here, as shown by the broken line in FIG. 2, the frequency of the received signal is one which is modulated into a triangular wave like the transmitted signal, but between the own vehicle and the object A. A delay of time τ required for the electromagnetic wave to reciprocate is generated for the transmitted signal. Therefore, when the transmitted signal and the received signal are compared on the same time axis, a temporal frequency difference f _B corresponding to the delay time τ of the received signal occurs between the frequencies of the two. Therefore, when the mixer 7 mixes the transmitted signal and the received signal, a beat signal having a frequency of the above-mentioned temporal frequency difference f _B is generated. Incidentally, when the object A is moving with respect to the own vehicle, the frequency of the received signal causes a Doppler shift with respect to the frequency of the transmitted signal. Since the frequency difference is smaller than the target frequency difference f _B , the Doppler shift is ignored here for convenience of description.

As is well known, the frequency f _{B of the} beat signal is basically proportional to the relative distance D of the object A to the own vehicle, and the following equation (1) is established between the frequency f _B and the relative distance D. .

D = kf _B (1) Here, "k" in the equation (1) basically depends on the velocity (light velocity) of the electromagnetic wave and the temporal change rate of the frequency of the transmitted signal. It is a fixed constant.

Therefore, by detecting the frequency f _{B of the} beat signal, the relative distance D of the object A can be detected by the equation (1). This is the basic principle of the FM-CW radar system adopted by the radar device of this embodiment.

However, in general, as described above, the mixer 7
The beat signal generated by includes a frequency component other than the frequency component corresponding to the relative distance D of the target object A. Further, when there are a plurality of target objects A, each target object A
The frequency component corresponding to the relative distance D is included in a complex manner.

For example, as shown in FIG. 1, when two objects A ₁ and A ₂ exist in the transmission direction of the electromagnetic wave beam B, the frequency distribution (spectral distribution) of the beat signal is
Basically, the distribution is as shown by the virtual line in FIG. That is, the spectrum distribution of the beat signal in this case is such that the spectrum level has a maximum value at the frequencies f ₁ and f ₂ corresponding to the relative distances D ₁ and D ₂ of the objects A ₁ and A ₂ , respectively. , And these frequencies f ₁ ,
The distribution is such that spectra of frequency components other than f ₂ are mixed. Further, the spectral distribution in the neighboring region of each frequency f _1, f ₂ is generally a distribution such as the frequency f _1, f ₂ symmetrically spectrum level on both sides as vertices decreases. The spectral levels at the frequencies f ₁ and f ₂ correspond to the wave receiving levels of the electromagnetic waves directly received by the antenna 3 among the electromagnetic waves reflected by the objects A ₁ and A _2. . In the following description, the case where there are _two objects A ₁ and A ₂ having different relative distances D in the transmission direction of the electromagnetic wave beam B as shown in FIG.

The beat signal generated by the mixer 7 is amplified to a beat signal having a required amplitude level by the amplifier 8 and further A / D converted by the A / D converter 9 at every predetermined sampling time. The amplitude data of the digitized beat signal is stored and held in the memory 10 in time series. In this case, the memory 10 stores and holds the amplitude data of the beat signal in time series within a predetermined period according to the timing signal given from the timing signal generation circuit 11, and, for example, the frequency of the transmitted / received waves both increases or decreases. During the period, the beat signal amplitude data is stored and held.

Then, based on the data stored and held in the memory 10, the signal processing device 12 obtains the relative distances D ₁ and D _{2 of the} objects A ₁ and A ₂ , respectively.

That is, referring to FIG. 4, in the signal processing device 12, first, the frequency analysis means 15 frequency-analyzes the beat signal data stored and held in the memory 10 to obtain a spectrum distribution thereof ( STEP 1). In this case, the frequency analysis unit 15 obtains the spectrum distribution of the beat signal by FFT (Fast Fourier Transform method) which is a calculation processing method of frequency analysis. Here, in this frequency analysis, as shown by the solid line in FIG. 3, discrete spectrum data is obtained for each predetermined unit frequency interval Δf. The unit frequency interval Δf corresponds to the frequency resolution of the device of this embodiment.

Next, the signal processing device 12 causes the maximum spectrum detecting means 16 to generate a spectrum (hereinafter referred to as a maximum spectrum) whose spectrum level becomes a maximum value of a predetermined level (threshold value) or more based on the spectrum data. ) Is detected (STEP 2). This detection is performed, for example, by detecting a spectrum having a spectrum level equal to or higher than the above threshold and having a spectrum level of frequencies around the threshold level changing from an increasing tendency to a decreasing tendency. In the spectral data of FIG. 3, reference numeral S _P, two spectrum denoted by S _q (frequency;
f _P , f _q ) will be detected as the maximum spectrum. The threshold value is set so as to exclude noise components and the like from the spectrum data of the beat signal.

Here, it is assumed that the beat signals are connected in the frequency direction.
Given a continuous spectral distribution, its spectrum
The Toll distribution is as shown by the phantom line in FIG.
A₁, A ₂Each relative distance D₁, D₂Corresponding to
Frequency f₁, F₂The spectral level is
The frequency analysis means has the following distribution.
In the frequency analysis of the beat signal by No. 15, between unit frequencies
Only discrete spectral data for each interval Δf can be obtained.
Therefore, from such discrete spectral data,
The maximum spectrum S obtained as described below_P, S_qFrequency
f_P, F_qIs an object A as shown in FIG.₁, A₂Fruit
Relative distance D₁, D₂Frequency f corresponding to ₁, F₂To
Although the values are close, in general, the frequency f₁, F₂When
Does not match.

Therefore, even if the relative distances of the objects A ₁ and A ₂ are obtained by the above equation (1) using the frequencies f _P and f _q of the maximum spectra S _P and S _q , the obtained relative distances are It is not always accurate.

Therefore, in the signal processing device 12, the maximum spectrums S _P and S _{q are} detected by the level center of gravity detecting means 17.
Predetermined frequency width Δf _W centered on the frequencies f _P and f _q of
(See FIG. 3) The frequency of the level center of gravity of the spectrum data is obtained (STEP 3), and the obtained frequency of the center of gravity is used by the distance detecting means 18 according to the equation (1) to obtain the objects A ₁ , A. ₂ of each relative distance D _1, obtaining the D ₂ (STEP4).

The processing for obtaining the frequency of this level centroid is
For example, the following operation is performed on the maximum spectrum S _p side corresponding to the object A ₁ .

That is, in the spectrum data of FIG.
For example, the predetermined frequency width Δf _W, For example,
Vector S_PFrequency f_PThe unit frequency around
4 times the interval Δf (Δf_W= 4 · Δf),
The frequency width Δf_WIn it, the maximum spectrum S_pIncluding
5 spectra S_P-2, S_P-1, S_p, S_{P + 1}, S
_{P + 2}Exists. At this time, the level of the signal processing device 12
The center-of-gravity detection means 17 uses the object A₁Maximum spectrum corresponding to
Tol S_pFrequency f of the center of gravity of the side spectrum data
_G(Hereinafter, the center of gravity frequency f_GBy the following equation (2)
Ask.

[0041]

[Equation 1]

Here, in equation (2), f_P-2, F
_P-1, F_p, F_{P + 1}, F_{P + 2}Is the spectrum S_P-2，
S_P-1, S_p, S_{P + 1}, S_{P + 2}Frequency of L_P-2, L
_P-1, L _p, L_{P + 1}, L_{P + 2}Is each spectrum S_P-2, S
_P-1, S_p, S_{P + 1}, S_{P + 2}At the spectral level of
It

To further generalize and explain the arithmetic processing, the predetermined frequency width Δf _{W is set} to the unit frequency interval Δf.
When N times (N: a predetermined even number), the frequency width Δf
Within _W , there are (N + 1) spectra S _{P- (N / 2) to} S _{P + (N / 2)} including the maximum spectrum S _p , and at this time, the level centroid detection means of the signal processing device 12 is present. 17 calculates the center-of-gravity frequency f _G by performing the arithmetic processing shown in the flowchart of FIG.

That is, with reference to FIG. 5, the level center of gravity detecting means 17 has each spectrum S existing within the frequency width Δf _W (= N · Δf) centered on the maximum spectrum S _P.
For _{P- (N / 2) ~S P} + (N / 2), sequentially from those of the low frequency side, spectrum level L of each spectrum _{S P- (N / 2) ~S} P + (N / 2) P- ( _{N / 2)} ~ LP _{+ (N / 2)} and frequency _{fP- (N / 2)} ~
A value obtained by multiplying with f _{P + (N / 2)} is obtained, and this value is cumulatively added, and at the same time, each spectrum S _{P- (N / 2) to} S
_{P + (N / 2)} spectrum level L _{P- (N / 2)} of ~L P + _{(N / 2)} values for cumulative addition of (STEP from STEP1 in FIG. 5
5). And the last spectrum S on the highest frequency side
_{When the} above cumulative addition operation for _{P + (N / 2)} is completed, the spectrum levels L _{P- (N / 2) to} L _{P + (N / 2)} and the frequency f
Cumulative addition value FL (s of the product of _{P- (N / 2) to} f _{P + (N / 2)}
um) by dividing the cumulative addition value L (sum) of the spectral levels L _{P- (N / 2) to} L _{P + (N / 2)} by
The center of gravity frequency f _G is obtained (STEP 6 in FIG. 5).

Therefore, the center-of-gravity frequency f _G is given by the following equation (3). In the equation (2), N = 4 in the equation (3).
And when.

[0046]

[Equation 2]

The level centroid detecting means 17, such processing is performed also for the maximum spectrum S _q side corresponding to the object A _2, thereby, the center of gravity frequency f _G corresponding to each object A _1, A ₂ Ask.

In the calculation processing for obtaining the center-of-gravity frequency f _G , of the spectra existing within the frequency width Δf _W , those having a spectrum level smaller than the threshold are excluded and the center-of-gravity frequency f _G is excluded. Ask for.

The predetermined frequency width Δf _W is preferably determined in consideration of the size of the object A, the spread of the spectrum distribution in the vicinity of the maximum spectrum, and the like.

In this way, each object A₁, A₂In response to
Obtained center-of-gravity frequency f_GIs shown in phantom in FIG.
Such as the actual spectral distribution that is continuous in the frequency direction.
Frequency f of the maximum value₁, F₂To estimate
The spectral distribution is at each frequency f₁, F₂In the vicinity of
The frequency f₁, F₂Symmetrical about both sides
Center of gravity f_GAnd the actual spectrum
Frequency f of maximum value in cloth₁, F₂Is almost the same as.
The actual spectrum distribution is the frequency f ₁, F₂
In the region near₁, F₂Centered around
It is considered that the distribution will be symmetrical on both sides.

Therefore, as described above, each object A₁, A₂
Center-of-gravity frequency f found corresponding to _GIs each object
A₁, A₂Relative distance D₁, D₂The actual frequency corresponding to
Number f₁, F₂It matches exactly. For example,
Target A ₁The spect corresponding to
Le S_P-2~ S_{P + 2}Center of gravity frequency f_GIs shown in the figure
Sea urchin spectrum S_P, S_{P + 1}Located between the frequencies of the poles
Large spectrum S_PFrequency f_PThan object A₁Fruit
Relative distance D₁Frequency f corresponding to₁Value close to
It

In the signal processing device 12, the center of gravity frequency f _G thus obtained is used to cause the distance detecting means 18 to calculate the relative distance D ₁ between the objects A ₁ and A ₂ according to the above equation (1).
Seeking D _2, and outputs the automatic travel control device (not shown) or the like relative distance D _1, D ₂ thereof obtained. In the radar device of this embodiment, the operation described above is periodically repeated.

As described above, in the radar apparatus of this embodiment, the relative distance D of each object A is obtained from the center-of-gravity frequency f _G to detect the distance without increasing the frequency resolution in the frequency analysis of the beat signal. The accuracy can be increased. On the contrary, this means that the frequency resolution of the beat signal can be made lower than before when the required accuracy of distance detection is the same as before. In this case, the processing time for distance detection can be shortened.

In the present embodiment, the center of gravity frequency f _G
After the equation (3) is obtained, the relative distance D of each object A is calculated.
However, for each spectrum in the frequency width Δf _W , the relative distance corresponding to the frequency is calculated by the equation (1), and the value of the relative distance calculated for each spectrum is used to calculate The relative distance D corresponding to the center-of-gravity frequency f _G may be directly obtained by the same calculation as the equation (3). In this case, the frequencies f _{P- (N / 2) to} f _{P + (N / 2)} of the respective spectra S _{P- (N / 2) to} S _{P + (N / 2 ) in} the equation (3) are calculated from those frequencies. If the distance is replaced with the relative distance corresponding to the frequency, the relative distance D corresponding to the center-of-gravity frequency f _G can be directly obtained.

Next, an example of the second aspect of the present invention will be described with reference to FIGS. 6 to 10. FIG. 6 is a system configuration diagram of the radar device of the present embodiment, FIGS. 7 and 8 are flowcharts for explaining the operation of the radar device of the present embodiment, and FIGS. 9 and 10 are operations of the eder device of the present embodiment. It is an explanatory view for explaining. In the following description, the same components as those of the above-described first embodiment will be designated by the same reference numerals and detailed description thereof will be omitted.

With reference to FIG. 6, the radar device of this embodiment detects the two-dimensional relative position of the object A such as another vehicle in front of the vehicle equipped with the same with respect to the own vehicle. The oscillator 1, the modulation control circuit 2, the isolator 4, the directional coupler 5, the circulator 6, the mixer 7, the amplifier 8, the A / D converter 9, the memory 10, and the like as in the above-described embodiment. A timing signal generation circuit 11 and is provided. These configurations are basically the same as those of the above-mentioned embodiment.

On the other hand, the radar apparatus of this embodiment includes a plurality of (five in this embodiment) antennas 3a to 3e for transmitting and receiving electromagnetic waves and antennas 3a to 3 for transmitting and receiving electromagnetic waves.
The antennas 3a to 3 for selectively switching e
Switching device 19 interposed between e and circulator 6
And a signal processing device 20 for arithmetically processing the data of the beat signal generated corresponding to each of the antennas 3a to 3e as described later. Here, corresponding to the configuration of the second aspect of the present invention, the oscillator 1, the modulation control circuit 2, the isolator 4, the directional coupler 5, the circulator 7, the switching device 19, and the antennas 3a to 3e are the wave transmitting means 21. The antennas 3a to 3e, the switching device 19 and the circulator 7 constitute the wave receiving means 22, and the mixer 7 constitutes the beat signal generating means 7. The signal processing device 20 is composed of an electronic circuit including a microcomputer and the like, and as its functional configuration, the frequency analysis means 23, the object frequency detection means 24, the distance detection means 25 and the level center of gravity detection means 26. It has and.

Next, the operation of the radar system will be described together with a detailed description of each part thereof.

The frequency-modulated transmission signal (see FIG. 2) output from the oscillator 1 is applied to the switching device 19 via the isolator 4, the directional coupler 5 and the circulator 6 as in the above-described embodiment. It

The switching device 19 synchronizes the antennas 3a to 3e connected to the circulator 6 with the modulation cycle of the transmission signal according to the timing signal output from the timing signal generation circuit 11 in conjunction with the modulation control circuit 2. Let's go,
As a result, the antennas 3a to 3e are sequentially connected to the circulator 6 via the switching device 19 with a time difference synchronized with the modulation period of the transmission signal, and the transmission signal is transmitted. Is given.

Then, each of the antennas 3a to 3e transmits an electromagnetic wave beam Ba to Be when given a transmitting signal. At this time, the antennas 3a to 3e are arranged close to each other and have directivity in different directions adjacent to each other. For example, the electromagnetic wave beam Bc corresponding to the antenna 3c is in front of the front of the own vehicle. The electromagnetic wave beams Bb, Ba corresponding to the antennas 3b, 3a are transmitted toward the right side (upper side in FIG. 6) of the electromagnetic wave beam Bc by a predetermined angle and correspond to the antennas 3d, 3e. The electromagnetic wave beams Bd and Be are transmitted to the left side (lower side in FIG. 6) of the electromagnetic wave beam Bc in a direction separated by a predetermined angle. When each of the antennas 3a to 3e transmits the electromagnetic wave beams Ba to Be, when an object A such as another vehicle exists in the transmitting direction of the electromagnetic wave beams Ba to Be, a reflected wave from the object A is present. Is received, and the received signal is input to the mixer 7 via the switching device 19 and the circulator 6. Then, the mixer 7 mixes the received signal and a part of the transmitted signal corresponding to the respective electromagnetic wave beams Ba to Be, as in the above-described embodiment, and thereby,
A beat signal having a frequency component corresponding to the relative distance of the object A existing in the transmission direction of the electromagnetic wave beams Ba to Be is generated.

The beat signal is an electromagnetic wave beam Ba to Be.
Are sequentially and selectively switched, so that each of the electromagnetic wave beams Ba to Be is sequentially generated with a time difference synchronized with the modulation cycle of the transmission signal. Then, the amplitude data of the beat signal corresponding to each of the electromagnetic wave beams Ba to Be is stored and held in the memory 10 in time series via the amplifier 8 and the A / D converter 9 as in the above-described embodiment. At this time,
The memory 10 separately stores and holds data of beat signals corresponding to the electromagnetic wave beams Ba to Be. In other words, the memory 11 stores five signals corresponding to the electromagnetic wave beams Ba to Be.
The data of the individual beat signals is stored and held.

Next, based on the beat signal data for each of the electromagnetic wave beams Ba to Be stored and held in the memory 10 in this way, the signal processing device 20 causes the self of each target object A as shown in the flowchart of FIG. The relative position with respect to the vehicle is determined. In the following description, two objects A ₁ and A ₂ (see FIG. 9) are arranged so as to straddle the electromagnetic wave beams Ba to Be in the transmission direction (front of the own vehicle). The case where there exists will be described.

Referring to FIG. 7, in the signal processing device 20, first, the frequency analysis means 23 frequency-analyzes the beat signal data corresponding to the electromagnetic wave beams Ba to Be stored and held in the memory 10. , The spectrum distribution of each beat signal is obtained (STEP 1). In this case, the frequency analysis means 23 obtains the spectrum distribution of each beat signal by FFT (Fast Fourier Transform method), as in the above-described embodiment.

Then, in the signal processing device 20, the object frequency detecting means 24 causes the electromagnetic wave beams Ba to Be to be transmitted in the respective transmitting directions based on the spectral distribution of the beat signals corresponding to the electromagnetic wave beams Ba to Be. Object A ₁ ,
The frequency corresponding to the relative distance of A ₂ is obtained as the object frequency (STEP 2). Here, each electromagnetic wave beam Ba-
The spectrum distribution of the beat signal corresponding to Be becomes the distribution (discrete spectrum data) as shown in FIG. 3 described in the above-mentioned embodiment, and each of the electromagnetic wave beams Ba to B.
The object frequency in the transmission direction of e can be obtained, for example, by obtaining the frequency (frequency f _P , f _q in FIG. 3) of the maximum spectrum corresponding to each object A ₁ , A ₂ .

Next, the signal processing device 20 calculates the above-mentioned equation (1) from the object frequency obtained by the distance detecting means 25 for each of the electromagnetic waves Ba to Be corresponding to the objects A ₁ and A _2. ) Is used to determine the relative distance in the transmission direction of each electromagnetic wave beam Ba-Be of each object A ₁ , A ₂ (STEP 3). In the following explanation, the electromagnetic wave beam B
The relative distances of the objects A ₁ and A ₂ corresponding to a are D _1a and D
_2a , the relative distances of the objects A ₁ , A ₂ corresponding to the electromagnetic wave beam Bb are D _1b , D _2b , ..., The relative distances of the objects A ₁ , A ₂ corresponding to the electromagnetic wave beam Be are D _1e , It is called D _2e .

Here, in this way, each electromagnetic wave beam Ba
~ Relative distances D _1a , D _2a , ...
, D _1e , D _2e are target objects A ₁ , recognized by the radar device of the present embodiment in the transmission directions of the electromagnetic wave beams Ba to Be (which are predetermined for the own vehicle). It indicates the relative position of A ₂ with respect to the own vehicle.

That is, as shown in FIG. 9, assuming that the position of the own vehicle is the origin O and the axes indicating the transmitting directions of the electromagnetic wave beams Ba to Be are axis a, axis b, ..., Axis e, for example, On the axis a, the relative distance D _1a from the origin O,
It is recognized that the objects A ₁ and A ₂ are present at the positions of the points P _1a and P _2a of D _2a , and the same applies to the other axes b to e.

Next, the signal processing device 20 uses the level barycenter detection means 26 to calculate the relative distances D _1a and D ₁ as described above on the basis of the spectral distributions obtained for the electromagnetic wave beams Ba to Be. _2a , ..., D _1e , D _2e , the spectral levels of frequencies corresponding to the relative distances D _1a , D _2a , ..., D _1e , D _2e and the electromagnetic wave beams Ba to Be corresponding to them are defined as described above. the transmitting direction and the determined point _{P 1a, P 2a, ......,} P 1e, correspondence to the P _2e (see FIG. 9), the spectrum level of the object frequencies corresponding to the respective object a _1, a ₂ 2 The position of the center of gravity of the dimensional level is set to each object A.
_{It is} calculated as the relative position of ₁ and A ₂ (STEP 4).

Here, in the case of the present embodiment, each relative distance
D_1a, D_2a, ……, D_1e, D_2eObject frequency corresponding to
Spectrum level of each electromagnetic wave beam Ba ~ Be
Spectral distribution of the obtained beat signal (discrete spectrum
It is the level of the maximum spectrum in the toll data.
For example, the spectrum data corresponding to the electromagnetic wave beam Ba
As shown in FIG. 3, the relative distance D_1a
The spectral level of the object frequency corresponding to
Cutle S_PIs the spectral level of the relative distance D _2aTo
The spectrum level of the corresponding frequency is the maximum spectrum S
_qIs the spectrum level of.

Then, the two-dimensional level barycenter of the spectral level corresponding to each of the objects A ₁ and A ₂ is obtained as follows.

That is, referring to FIG. 10, an XY Cartesian coordinate axis having an origin O as the position of the own vehicle and an X axis as an axis c in the transmitting direction of the electromagnetic wave beam Bc (the front front direction of the own vehicle) is shown. Assuming that an axis L orthogonal to the X and Y axes passing through the origin O is an axis indicating the magnitude of the spectrum level, the object frequency at each relative distance D _1a , D _2a , ..., D _1e , D _2e . The spectral level of the points P _1a , P _2a , ...,
By associating with P _1e and P _2e , a two-dimensional spectral distribution can be visually obtained corresponding to the respective objects A ₁ and A ₂ as shown in FIG.

₂ corresponding to each of the objects A ₁ and A 2
The position of the dimensional level barycenter is X- of the position of the level barycenter.
The Y coordinate component is associated with each of the objects A ₁ and A ₂ (X _1G , Y
_1G ), (X _2G , Y _2G ), each point P _1a , P _2a , ...
,, P _1e , P _2e XY coordinate components are (x _1a , y _1a ),
(X _2a , y _2a ), ..., (x _1e , y _1e ), (x _2e ,
y _2e ), the spectral levels corresponding to the respective points P _1a , P _2a , ..., P _1e , P _2e are _defined as L _1a , L _2a , ..., L _1e , L _2e , and the following equations (4), (5) ) Is required.

[0074]

[Equation 3]

Note that the XY coordinate components of the points P _1a , P _2a , ..., P _1e , P _2e have corresponding relative distances D _1a , D _2a ,.
, D _1e , D _2e and the transmission angles of the electromagnetic wave beams Ba to Be, and the transmission directions of the electromagnetic wave beams Ba to Be are deviated by an angle θ (see FIG. 9), For example, the X coordinate component x _1a of the point P _1a is the relative distance D _1a
And the transmission angle 2θ of the electromagnetic wave beam Ba with respect to the X-axis, x _1a = D _1a · cos 2θ, and the Y coordinate component y _1a is obtained by y _1a = D _1a · sin 2θ.

When obtaining the position of such a two-dimensional level center of gravity, the relative distances D _1a , D _2a , ...,
D _1e and D _2e correspond to the object A ₁ and the object A ₂
In the present embodiment, the level center of gravity detecting means 26 performs two-dimensional processing corresponding to each of the objects A ₁ and A ₂ by performing the processing shown in the flowchart of FIG. The position (XY coordinate component) of the dynamic level center of gravity is obtained.

That is, with reference to FIG. 8 and FIG. 10, first, the points P _1a ,
The smallest relative distance is extracted from P _2a , ..., P _1e , P _2e as a reference point (STEP 1 in FIG. 8).

Then, in each direction on the left side of the direction corresponding to the extracted reference point, all the points adjacent to the reference point are extracted (STEP 2), and all the extracted points and the reference points are extracted. The cumulative values of the X-coordinate component values of the points and the spectral level values corresponding to these points are cumulatively added, and this is obtained as a cumulative addition value XL (sum). Similarly, the multiplication values of the Y coordinate component values of all the points (including the reference point) extracted in STEP 2 and the spectrum level values are cumulatively added, and this is obtained as a cumulative addition value YL (sum). Further, the spectrum levels of all the points extracted in STEP 2 and the reference point are cumulatively added, and this is obtained as a cumulative addition value L (sum) (STEP 3).

In this case, the judgment as to whether or not the point is adjacent to the reference point is made, for example, by judging whether or not the relative distance of the point is within a predetermined numerical range with respect to the relative distance of the reference point. The numerical range is determined in consideration of the size of the object.

In the processing up to STEP 3, if the point having the smallest relative distance is the point P _1c , the points P _1C , P
_The above cumulative addition operation is performed on _1d and P _1e .

Then, for each direction on the right side of the direction corresponding to the reference point, all the points adjacent to the reference point are extracted (STEP 4), and all the extracted points are
The multiplication value of the value of the X coordinate component of these points and the value of the spectrum level corresponding to these points is cumulatively added to the cumulative addition value XL (sum) obtained in STEP3. Similarly, the multiplication value of the Y coordinate component value of all the points extracted in STEP 4 and the spectrum level value is set to the STE.
The cumulative addition value YL (sum) obtained in P3 is cumulatively added. Further, the spectrum levels of all the points extracted in STEP 4 are cumulatively added to the cumulative addition value L (sum) obtained in STEP 3 (STEP 5).
Here, the judgment as to whether or not the point is adjacent to the reference point is
As described above.

The cumulative addition values XL (sum), YL (sum), L (su) finally obtained by the above arithmetic processing
m) are the numerator of the formula (4), the numerator of the formula (5), and the denominator of the formulas (4) and (5), respectively.
L (sum) and YL (sum) are respectively L (sum)
By dividing by, the position (X _1G , Y _1G ) of the two-dimensional level center of gravity corresponding to one object A ₁ can be obtained (STEP
6).

The level center of gravity detecting means 26 then detects the position (X _1G , Y) of the two-dimensional level center of gravity thus obtained.
_1G ) as the relative position of the object A ₁ (STE
P7), regarding the remaining points that have not been subjected to the arithmetic processing (in the present embodiment, points P _{2a to} P _2e remain), STEP 1
Up to STEP 7, the two-dimensional level barycentric position (X _2G , Y _2G ) corresponding to the object A ₂ is obtained,
When all the points P _1a , P _2a , ..., P _1e , P _2e are finally processed, the above processing is ended.

The positions (X _1G , Y _1G ), (X _2G , Y _2G ) of the two-dimensional level barycenters thus obtained accurately match the actual relative positions of the objects A ₁ , A _2. To do.

That is, for example, the spectral levels corresponding to the five points P _{1a to} P _1e obtained for the object A ₁ are the electromagnetic wave beams Ba corresponding to the respective points P _{1a to} P _1e.
~ Be corresponds to the received wave level of the reflected wave (direct wave) from the object A ₁ , and the received wave level is the object A.
_It is considered to be maximum when the electromagnetic wave beam is transmitted in the direction that matches the actual direction of ₁ .

For example, with reference to FIG. 10, the direction in which the object A ₁ is substantially equal to the wave-transmitting direction (axis c) of the electromagnetic wave beam Bc and the wave-transmitting direction (axis d) of the electromagnetic wave beam Bd. , The spectral level of the five points P _{1a to} P _1e obtained for the object A ₁ is highest at the point P _1c as shown in FIG. As it shifts, the spectrum level becomes smaller. However, the direction in which the object A ₁ is located and the electromagnetic wave beam B
The transmission direction of c does not always match, and originally,
It is considered that when the electromagnetic wave beam is transmitted in the direction between the electromagnetic wave beams Bc and Bb, the spectrum level at the point obtained corresponding to the electromagnetic wave beam becomes the maximum.

On the other hand, as described above, the object A₁Get about
Position of the center of gravity (X_1G, Y _1G) Is the implementation described above
Each point P basically follows the same principle as the example._1a~
P_1eFrom the discrete spectral level data at
It estimates the point that maximizes the vector level.
is there.

[0088] Therefore, the position of the level centroid obtained for the object _{A 1 (X 1G, Y 1G} ) is matched well the actual position and accuracy of the object A _1, is the same for the object A _2.

As described above, according to the radar apparatus of this embodiment, the relative positions of the objects A ₁ and A ₂ existing in the transmission area of the electromagnetic wave beams Ba to Be can be accurately detected. Also, a large number of electromagnetic wave beams B having different transmitting directions
Since a to Be are used, the detection range of the object can be wide.

In the present embodiment, when the relative distance of each object A in the transmission direction of each electromagnetic wave beam Ba to Be is obtained, the beat signals obtained corresponding to each electromagnetic wave beam Ba to Be are discrete. The maximum spectrum in various spectrum data is detected, and the relative distance is obtained by the frequency of the maximum spectrum.However, similarly to the above-described embodiment, the center of gravity frequency is obtained, and the relative distance is obtained by the center of gravity frequency. Good. In this case, it is preferable to estimate the spectrum level of the center of gravity frequency necessary for obtaining the relative position of each object by some method, but the spectrum level of the maximum spectrum may be used as the spectrum level of the center of gravity frequency. . Further, assuming that the spectral distribution in the vicinity of the frequency corresponding to the relative distance of the object is, for example, a normal distribution, the spectral level of the centroid frequency (which is the level of the apex of the normal distribution) is calculated from the discrete spectral data. It is also possible to ask. In addition, a general spectral distribution in the vicinity of the frequency corresponding to the relative distance of the object is set beforehand based on experiments, etc., and the set spectral distribution is compared and made to correspond to the discrete spectral data of the beat signal. Thus, it is possible to estimate the spectrum level of the center of gravity frequency. Further, in general, the sum of the spectral levels of the discrete spectral data in the vicinity of the frequency corresponding to the relative distance of the object is approximately proportional to the spectral level of the apex of the spectral distribution, and therefore in the embodiment of the first aspect described above. As described above, it is also possible to obtain the sum of the levels of each spectrum within a predetermined frequency width centered on the frequency of the maximum spectrum and obtain the spectrum level of the centroid frequency from the value of the sum.

Further, in the present embodiment, the relative position of the object is obtained by using the XY Cartesian coordinate system.
It is also possible to use a two-dimensional polar coordinate system whose origin is the position of the own vehicle.

In each of the embodiments described above,
I used FFT to analyze the frequency of the beat signal.
For example, frequency analysis can be performed using a number of bandpass filters.

Further, in each of the embodiments described above, the relative distance of the object is obtained by the above equation (1). However, the deviation of the frequency of the transmitted signal from the set value,
It is preferable to make a correction in consideration of the mounting position of the antenna and the like. When such a correction is performed, the correction may be performed by multiplying the relative distance D obtained by the equation (1) by a predetermined correction coefficient, but each frequency that the beat signal can detect in advance. Prepare the relative distance obtained by including the correction for each as map data,
The relative distance of the object may be directly obtained using the map data. By doing so, the processing time can be greatly shortened, especially for the case where the number of data is large as in the embodiment of the second aspect described above.

[0094]

As is apparent from the above description, according to the first aspect of the present invention, the spectral level is determined to be the maximum value of the predetermined level or more from the discrete spectral distribution of the beat signal at each unit frequency interval. Then, the frequency of the maximum spectrum is obtained, and the frequency of the level center of gravity of the spectral distribution within a predetermined frequency width before and after the frequency of the maximum spectrum is obtained, and the frequency of the obtained level center of gravity is associated with the relative distance of the object. By obtaining the relative distance of the target object as the frequency to be used, the detection accuracy of the relative distance of the target object can be improved without increasing the frequency resolution in the frequency analysis of the beat signal. And, on the contrary, it means that the frequency resolution in the frequency analysis of the beat signal can be reduced without impairing the detection accuracy of the relative distance of the target object, and thus the detection of the relative distance of the target object can be performed. Therefore, the processing speed can be improved.

Further, according to the second aspect of the present invention, a plurality of electromagnetic wave beams having different transmitting directions are used, and the spectrum of the object frequency obtained corresponding to the relative distance of the object for each electromagnetic wave beam. By obtaining the position of the two-dimensional level centroid of the level and using the obtained position of the two-dimensional level centroid as the relative position of the object, the relative position of the object can be obtained with high accuracy.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an example of a radar device according to a first aspect of the present invention.

FIG. 2 is a diagram for explaining the operation of the radar device of FIG.

FIG. 3 is a diagram for explaining the operation of the radar device of FIG.

4 is a flowchart for explaining the operation of the radar device of FIG.

5 is a flowchart for explaining the operation of the radar device in FIG.

FIG. 6 is a system configuration diagram of an example of a radar device according to a second aspect of the present invention.

7 is a flow chart for explaining the operation of the radar device of FIG.

8 is a flow chart for explaining the operation of the radar device of FIG.

FIG. 9 is an explanatory diagram for explaining the operation of the radar device of FIG. 1.

10 is an explanatory diagram for explaining the operation of the radar device of FIG.

[Explanation of symbols]

7 ... Beat signal generating means, 13, 21 ... Wave transmitting means, 1
4, 22 ... Receiving means, 15, 23 ... Frequency analyzing means, 1
6 ... Maximum spectrum detecting means, 17, 26 ... Level center of gravity detecting means, 18, 25 ... Distance detecting means, 24 ... Object frequency detecting means.

Claims (4)

[Claims] 1. A transmitting means for transmitting an electromagnetic wave whose frequency is temporally modulated, a receiving means for receiving a reflected wave from an object existing in the transmitting direction of the electromagnetic wave, and a transmitting means for the electromagnetic wave. Beat signal generating means for generating a beat signal having a frequency corresponding to the relative distance of the object by mixing a part of the transmitted signal and the received signal of the reflected wave, and performing frequency analysis on the beat signal. Frequency analysis means for obtaining a spectrum distribution of the beat signal for each predetermined unit frequency interval, maximum spectrum detection means for obtaining a frequency of a maximum spectrum at which the spectrum level has a maximum value of a predetermined level or more, and the maximum spectrum detection means. Level centroid detection means for obtaining the frequency of the level centroid of the spectral distribution within a predetermined frequency range extending before and after the frequency of the spectrum, and the frequency of the level centroid is the object Radar apparatus characterized by comprising a frequency corresponding to the relative distance and distance detecting means for obtaining a relative distance of the object. 2. The level center of gravity detection means obtains a sum of values obtained by multiplying the frequency of each spectrum of the spectrum distribution within a predetermined frequency width extending before and after the frequency of the maximum spectrum by the level of the spectrum, 2. The radar device according to claim 1, wherein the frequency of the center of gravity of the level is obtained by dividing the obtained total sum by the total sum of the levels of the respective spectra within the frequency width. 3. A wave transmission means for transmitting an electromagnetic wave beam whose frequency is temporally modulated in a plurality of directions adjacent to each other,
Receiving means for receiving, for each electromagnetic wave beam, a reflected wave from an object existing in the transmitting direction of the electromagnetic wave beam, a part of the transmitted signal of each electromagnetic wave beam, and the reception of the reflected wave corresponding thereto. Beat signal generation means for mixing a wave signal with each other to generate a beat signal having a frequency corresponding to the relative distance of the object in the transmission direction of each electromagnetic beam, and frequency analysis of the beat signal corresponding to each electromagnetic beam Frequency analysis means for obtaining the spectrum distribution of the beat signal, and object frequency detection means for obtaining the frequency of the spectrum corresponding to the relative distance in the transmission direction of each electromagnetic wave beam of the object from the spectrum distribution of each beat signal. A distance detecting means for obtaining a relative distance of the object in the transmission direction of each electromagnetic beam from the object frequency, and a phase of the object by the distance detecting means. The position of the two-dimensional center of gravity of the spectral level of the object frequency corresponding to the set of the relative distance of the object and the transmission direction of the electromagnetic beam is found for each electromagnetic wave beam for which the distance has been found, and the position is found. A radar apparatus, comprising: a level center of gravity detecting means for obtaining a position of a two-dimensional level center of gravity as a two-dimensional relative position of the object. 4. The level center of gravity detecting means determines a position of a position determined by a relative distance of the object for each electromagnetic beam and a transmission direction of the electromagnetic beam for each electromagnetic beam for which a relative distance of the object is obtained. A two-dimensional coordinate component is multiplied by a spectrum level of the object frequency corresponding to the position to obtain a sum of values for each coordinate component, and the obtained sum is obtained for each coordinate component. The radar device according to claim 3, wherein the coordinate component of the position of the two-dimensional level barycenter is obtained by dividing by the total sum of.