JP2020030140A - Target detection device and target detection method - Google Patents

Abstract

To provide a target detection device and a target detection method capable of obtaining a desired range of a detection speed in a state where speed resolution is made fine.SOLUTION: A target detection device according to an embodiment comprises: a generation unit; and a detection unit. The generation unit performs frequency analysis to a beat signal obtained by mixing a frequency-modulated transmission wave with a reflected wave of a transmission wave due to a target to generate a two-dimensional frequency spectrum having a frequency axis corresponding to the distance and relative speed of the target. The detection unit detects the distance and relative speed of the target on the basis of a peak extracted from the two-dimensional frequency spectrum generated by the generation unit. Also, the detection unit shifts a predetermined speed range associated with the frequency axis corresponding to the relative speed in an upper limit direction or a lower limit direction in accordance with a traveling state of an own vehicle.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a target detection device and a target detection method.

  2. Description of the Related Art Conventionally, as a target detection device that detects a target, a radar device that transmits a frequency-modulated signal and detects target information including a distance to the target and a relative speed has been proposed (for example, Patent Document 1). 1). Such a radar device is also called an FCM (Fast Chirp Modulation) type radar device.

JP-A-2006-3873

  However, in the above-described radar apparatus, there is a trade relationship between the maximum detection speed, which is a detectable speed range, and the speed resolution. Therefore, it has been a problem to obtain a desired speed range with the speed resolution being fine.

  The present invention has been made in view of the above, and an object of the present invention is to provide a target detection device and a target detection method capable of obtaining a desired detection speed range in a state where the speed resolution is fine. .

  In order to solve the above-described problem and achieve the object, a target detection device according to the present invention includes a generation unit and a detection unit. The generation unit performs a frequency analysis on a beat signal obtained by mixing a frequency-modulated transmission wave and a reflected wave of the transmission wave by the target to correspond to the distance and relative speed of the target. A two-dimensional frequency spectrum having a frequency axis is generated. The detection unit detects a distance and a relative speed of the target based on a peak extracted from the two-dimensional frequency spectrum generated by the generation unit. Further, the detection unit moves in a predetermined speed range corresponding to a frequency axis corresponding to the relative speed in an upper limit direction or a lower limit direction according to a traveling state of the host vehicle.

  According to the present invention, a desired detection speed range can be obtained with the speed resolution being fine.

FIG. 1A is a diagram illustrating an outline of a target detection method according to the embodiment. FIG. 1B is a diagram illustrating an outline of a target detection method according to the embodiment. FIG. 1C is a diagram illustrating an outline of the target detection method according to the embodiment. FIG. 2 is a block diagram of the radar device. FIG. 3 is a diagram illustrating the processing content of the generation unit. FIG. 4 is a diagram illustrating the processing content of the generation unit. FIG. 5 is a diagram illustrating the shift processing of the detection speed range by the peak extracting unit. FIG. 6 is a diagram illustrating a shift process of the detection speed range by the peak extraction unit. FIG. 7 is a diagram illustrating a shift process of the detection speed range by the peak extraction unit. FIG. 8 is a flowchart illustrating a processing procedure of processing performed by the radar device.

  Hereinafter, an embodiment of a target detection device and a target detection method disclosed in the present application will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited by this embodiment. Hereinafter, a case will be described in which a radar device that is the target detection device according to the embodiment executes the target detection method.

  First, an outline of a target detection method according to the embodiment will be described with reference to FIGS. 1A to 1C. 1A to 1C are diagrams illustrating an outline of a target detection method according to the embodiment. FIG. 1A shows a host vehicle MC on which the radar device 1 is mounted, and another vehicle OC preceding the host vehicle MC.

  As shown in FIG. 1A, a radar device 1 according to the embodiment is mounted, for example, on a front end of a vehicle MC, and detects a moving object such as another vehicle OC and a target such as a stationary object. The radar device 1 shown in FIG. 1A is, for example, a FCM (Fast Chirp Modulation) type radar device.

  The FCM method includes transmitting a transmission wave in which a plurality of chirp waves Ch <b> 1 to Chn (see FIG. 1B) whose frequency continuously changes are repeated, and includes a distance and a relative speed with each target existing within a detection range. This is a method for detecting target information.

  Specifically, the FCM radar apparatus 1 generates target information by performing “frequency analysis processing”, “peak extraction processing”, and “target detection processing”.

  In the “frequency analysis process”, a frequency analysis is performed on a beat signal obtained by mixing a frequency-modulated transmission wave (chirp wave) and a reflected wave of the transmission wave from the target. More specifically, in the “frequency analysis processing”, beat signals are grouped in units of chirps to form two-dimensional data (a signal time axis for one chirp and a chirp number axis), and a two-dimensional fast Fourier transform processing (hereinafter, referred to as “fourth-order”). By performing the two-dimensional FFT processing, a two-dimensional frequency spectrum having a distance frequency axis corresponding to the signal time axis and a relative velocity frequency axis corresponding to the chirp number axis is generated. In the two-dimensional frequency spectrum, each frequency corresponding to the distance (vertical distance) to the target (hereinafter referred to as distance bin) and each frequency corresponding to the relative speed with respect to the target (hereinafter referred to as speed bin) ), For example, power (see FIG. 1B).

  In the “peak extraction processing”, a peak whose power is equal to or more than a predetermined value is extracted from the generated two-dimensional frequency spectrum. In the “peak extraction processing”, an arbitrary priority range (range of speed bins) is selected from the below-described detected speed ranges in the relative speed direction in the two-dimensional frequency spectrum, and the peaks in such priority ranges are given priority. To extract. The “target detection process” detects a distance (longitudinal distance) and a relative speed of the target based on the extracted peak. Specifically, in the “target detection process”, the distance bin corresponding to the peak is detected as the distance of the target, and the speed bin is detected as the relative speed of the target.

  Here, the relationship between the maximum detection speed and the speed resolution in the FCM method will be described with reference to FIG. 1B. Here, the maximum detection speed is a range of a relative speed that can be detected in the peak extraction process (hereinafter, sometimes referred to as a detection speed range), and the speed resolution is a memory interval of a speed bin in the peak extraction process. It is.

  As shown in FIG. 1B, in the FCM method, in the relative speed detection, the longer the modulation time of each of the chirp waves Ch1 to Chn, the smaller the maximum detection speed (the narrower the detection speed range). On the other hand, the longer the modulation time of each of the chirp waves Ch1 to Chn, the finer the speed resolution becomes.

  For example, when the maximum detection speed is small (the detection speed range is narrow), the actual speed outside the detection speed range is repeated (so-called speed turning back), and a peak having a speed within the detection speed range may be extracted. Therefore, if the modulation time is shortened and the maximum detection speed is increased (the detection speed range is widened), the speed resolution becomes coarse. For example, when there are a plurality of targets with different relative speeds at the same distance, one object It may be detected as a target (that is, only one peak is extracted). As described above, the speed resolution and the maximum detection speed are in a trade-off relationship, and it is difficult for the conventional target detection method to obtain a desired detection speed range while keeping the speed resolution fine.

  Therefore, in the target detection method according to the embodiment, the detected speed range (an example of a predetermined speed range) itself is shifted according to the traveling state of the host vehicle MC. Specifically, in the target detection method according to the embodiment, in the “peak extraction process”, the detected speed range is moved in the upper limit direction and the lower limit direction according to the traveling state of the host vehicle MC. The traveling state is a state when the vehicle MC is traveling, and includes, for example, the traveling speed of the vehicle MC, the presence or absence of a stop, and the presence or absence of a traffic jam.

  For example, as shown in FIG. 1C, the target detection method according to the embodiment uses a detection speed range that is initially set as a range from speed bin 0 to speed bin fv3 according to the traveling state of the host vehicle MC. Shift to the range from speed bin -fv1 to speed bin fv2. This can be realized, for example, by moving the speed bin fv3, which is the upper limit, to the speed bin -fv1. That is, the detection speed range in the peak extraction processing is shifted in the lower limit direction. As a result, a target having a negative relative speed can be detected. In other words, a target that has been erroneously detected as a positive relative speed due to the speed return can be correctly detected as a target having a negative relative speed. Further, in the target detection method according to the embodiment, since the detection speed range is shifted to a position in the detection speed range to be prioritized while maintaining the width of the detection speed range, the speed resolution does not deteriorate.

  That is, in the target detection method according to the embodiment, the speed resolution is kept fine by shifting the detection speed range to the speed range of the target to be detected preferentially according to the traveling state of the host vehicle MC. It is possible to obtain a desired detection speed range while performing the above operation.

  A specific example of movement of the detection speed range according to each traveling state will be described later with reference to FIGS.

  Next, the configuration of the radar device 1 according to the embodiment will be described with reference to FIG. FIG. 2 is a block diagram of the radar device 1. As shown in FIG. 2, the radar device 1 is connected to a vehicle control device 2.

  The vehicle control device 2 controls a vehicle such as a PCS (Pre-crash Safety System) or an AEB (Advanced Emergency Braking System) based on the detection result of the target by the radar device 1. The radar device 1 may be used for various purposes other than the on-vehicle radar device (for example, monitoring an airplane or a ship).

  The radar device 1 includes a transmitting unit 10, a receiving unit 20, and a processing unit 30. The transmission unit 10 includes a signal generation unit 11, an oscillator 12, and a transmission antenna 13. The signal generation unit 11 generates a modulation signal whose voltage changes in a sawtooth waveform and supplies the modulation signal to the oscillator 12. The oscillator 12 generates a chirp signal ST based on the modulation signal generated by the signal generation unit 11, and outputs the generated chirp signal ST to the transmission antenna 13.

  The transmission antenna 13 converts the chirp signal ST input from the oscillator 12 into a transmission wave SW, and outputs the transmission wave SW to the outside of the vehicle MC. The transmission wave SW output by the transmission antenna 13 has a waveform in which a plurality of chirp waves Ch1 to Chn are repeated. The transmission wave SW transmitted from the transmission antenna 13 ahead of the own vehicle MC is reflected by a target such as another vehicle OC and becomes a reflected wave.

  The receiving unit 20 includes a plurality of receiving antennas 21a to 21d forming an array antenna, mixers 22a to 22d, and A / D converters 23a to 23d. Each receiving antenna 21 receives a reflected wave from a target as a received wave RW, converts the received wave RW into a received signal SR, and outputs the received signal SR to a mixer 22 provided for each receiving antenna 21. Although the number of receiving antennas 21 shown in FIG. 2 is four, it may be three or less or five or more.

  The reception signal SR output from each reception antenna 21 is input to the mixer 22 after being amplified by an amplifier (not shown) (for example, a low noise amplifier). The mixer 22 mixes (mixes) a part of the chirp signal ST and the received signal SR, removes unnecessary signal components, generates a beat signal SB, and outputs the beat signal SB to the A / D converter 23.

Thus, the chirp signal ST the frequency _{f ST} (hereinafter, the transmission frequency _{f ST} and described) and the frequency _{f SR} of the received signal SR (hereinafter, the receiving frequency _f to as _SR) and the difference to become beat frequency _{f SB} of ( = F _ST −f _SR ). The beat signal SB generated by the mixer 22 is output to the processing unit 30 after being converted into a digital signal by the A / D converter 23.

  The processing unit 30 includes a transmission control unit 31, a signal processing unit 32, and a storage unit 33. The signal processing unit 32 includes a generation unit 321 and a detection unit 322. The detection unit 322 includes a peak extraction unit 322a, a calculation unit 322b, and an output unit 322c.

  The processing unit 30 is, for example, a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output port, and the like, and controls the entire radar device 1.

  When the CPU of the microcomputer reads out and executes the program stored in the ROM, the microcomputer functions as the transmission control unit 31 and the signal processing unit 32. Note that at least a part or all of the transmission control unit 31 and the signal processing unit 32 may be configured by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

  The storage unit 33 corresponds to a RAM. The storage unit 33 stores, for example, information of various programs executed by the radar device 1 and the like.

  The transmission control unit 31 controls the signal generation unit 11 of the transmission unit 10, and causes the signal generation unit 11 to output a modulated signal whose voltage changes in a sawtooth manner to the oscillator 12. As a result, a chirp signal ST whose frequency changes with the passage of time is output from the oscillator 12 to the transmitting antenna 13.

  The signal processing unit 32 performs a two-dimensional FFT process on the beat signal SB output from each A / D converter 23, and based on the result of the two-dimensional FFT process, a distance, a relative speed, and an azimuth of the target. Is calculated. Hereinafter, processing of each unit of the signal processing unit 32 will be described.

  The generation unit 321 generates a two-dimensional frequency spectrum having a frequency axis corresponding to the distance and the relative speed of the target by performing frequency analysis on each of the beat signals SB output from each of the A / D converters 23. I do. Here, the processing content of the generation unit 321 will be specifically described with reference to FIGS.

  FIG. 3 and FIG. 4 are diagrams illustrating the processing contents of the generation unit 321. In FIG. 3, two thick white downward arrows are used to separate the three regions, but these regions are referred to as an upper stage, a middle stage, and a lower stage in order from the top.

First, the point that the beat signal is generated by the transmission process by the transmission unit 10 and the reception process by the reception unit 20 has already been described. Thereby, as shown in the upper part of FIG. 3, a beat signal having a beat frequency f _SB (= fST−fSR) that is a difference between the transmission frequency f _ST and the reception frequency f _SR is generated for each chirp wave. Here, the beat signal obtained by the first chirp wave Ch1 is “B1”, the beat signal obtained by the second chirp wave Ch2 is “B2”, and the beat signal obtained by the n-th chirp wave Chn Is “Bn”.

In the example shown in the upper part of FIG. 3, the transmission frequency f _ST increases from the reference frequency f0 with time with a gradient θ (= (f1−f0) / Tm) with time for each chirp wave, and becomes the maximum frequency f1. When it reaches, it has a sawtooth waveform that returns to the reference frequency f0 in a short time. Further, the modulation frequency Δf of the chirp wave can be expressed by Δf = f1−f0.

Although not shown, the transmission frequency f _ST reaches the maximum frequency f1 from the reference frequency f0 in a short time for each chirp wave, and the inclination θ (= (f1−f0) from the maximum frequency f1 with time. ) / Tm), and may have a sawtooth waveform that reaches the reference frequency f0.

The generation unit 321 first performs “first FFT processing” on each of the generated and input beat signals. As described above, the transmission wave based on the transmission signal is transmitted from the transmission antenna 13, and the transmission wave is reflected by the target and becomes a reflected wave, and the reflected wave is received by the reception antenna 21 as a reception wave and the reception signal is received. Is output as The period from when the transmission wave is transmitted from the transmission antenna 13 to when the reception signal is output increases / decreases in proportion to the distance between the target and the radar apparatus 1, and the beat frequency f _SB which is the frequency of the beat signal Is proportional to the distance between the target and the radar device 1.

  Therefore, in the frequency spectrum of the beat signal generated by performing the first FFT processing on the beat signal, a peak appears at a frequency bin fr (distance bin fr) corresponding to the distance to the target. Therefore, the distance to the target can be detected by specifying the distance bin fr where such a peak exists.

  By the way, when the relative speed between the target and the radar device 1 is zero, no Doppler component occurs in the received signal and the phases are the same between the received signals corresponding to each chirp wave. The phase is the same. On the other hand, when the relative speed between the target and the radar device 1 is not zero, a Doppler component occurs in the received signal, and the phase differs between the received signals corresponding to each chirp wave. A phase change corresponding to the Doppler frequency appears.

  The middle part of FIG. 3 shows an example of the first FFT processing result of the temporally continuous beat signals (B1 to B8) and the phase change of the peak between the beat signals. In this example, the same distance bin fr10 has a peak, indicating that the phase of such a peak is changing.

  As described above, when the relative speed between the target and the radar apparatus 1 is not zero, a change in phase according to the Doppler frequency appears at the peak of the same target between beat signals. Therefore, by arranging the frequency spectra obtained by the first FFT processing of each beat signal in chronological order and performing the “second FFT processing” as shown in the lower part of FIG. 3, a peak is found in the frequency bin for the Doppler frequency. The appearing frequency spectrum can be obtained. That is, the generation unit 321 performs the two-time FFT processing, which is a frequency analysis, to generate a two-dimensional frequency spectrum in which a peak appears for each distance bin (distance direction) and each speed bin (relative speed direction) shown in FIG. Can be obtained. The calculating unit 322b at the subsequent stage can detect the frequency bin in which the peak appears, that is, the speed bin, thereby detecting the relative speed with respect to the target.

  Returning to FIG. 2, the detection unit 322 will be described. The detection unit 322 detects the distance and the relative speed of the target based on the peak extracted from the two-dimensional frequency spectrum generated by the generation unit 321. Hereinafter, each unit included in the detection unit 322 will be described.

  The peak extracting unit 322a extracts a peak whose power is equal to or more than a threshold from the two-dimensional frequency spectrum generated by the generating unit 321. Specifically, the peak extracting unit 322a first sets the detected speed range corresponding to the relative speed frequency axis of the two-dimensional frequency spectrum generated by the generating unit 321 in the upper limit direction or the lower limit direction according to the traveling state of the vehicle. Shift to Then, the peak extracting unit 322a extracts a peak whose power is equal to or more than a predetermined value from the shifted detection speed range. For example, the peak extracting unit 322a selects a priority range from the shifted detection speed range, and preferentially extracts a peak in the priority range.

  Here, the shift processing of the detected speed range in each traveling state by the peak extracting unit 322a will be described with reference to FIGS.

  FIG. 5 to FIG. 7 are diagrams illustrating the shift processing of the detection speed range by the peak extracting unit 322a. FIG. 5 shows a shift process when the own vehicle MC is stopped, FIG. 6 shows a shift process when the own vehicle MC is running, and FIG. 7 shows a shift process when the own vehicle MC is in a traffic jam. . In FIGS. 5 to 7, the two-dimensional frequency spectrum represents the peaks of the speed bin and the distance bin on a two-dimensional plane, and one cell corresponds to one peak.

  First, a shift process when the host vehicle MC stops will be described with reference to FIG. Note that the traveling state indicating that the host vehicle MC is stopped is, for example, that the traveling speed of the host vehicle MC is substantially zero or that the shift lever is located at the parking position.

  The peak extracting unit 322a shifts the detected speed range such that the speed ranges in the departure direction and the approach direction with respect to the own vehicle MC are substantially the same in the traveling state indicating that the own vehicle MC is stopped. I do.

  In the example illustrated in FIG. 5, the peak extracting unit 322a sets the speed bins fv1 to fv6, which are the detected speed ranges before the shift, to the speed bins -fv3 to fv3 after the shift. That is, the peak extracting unit 322a shifts the relative speeds in the separation direction (positive) and the approaching direction (negative) to the detection speed range in which the relative speeds in the separation direction (positive) and the approach direction (negative) can be uniformly detected, while keeping the entire width of the detection speed range.

  In other words, when the own vehicle MC is stopped, it is necessary to detect the target that is coming away and approaching evenly. Therefore, the detection speed ranges in the separating direction and the approaching direction are made substantially the same, so that the own vehicle MC is separated from the own vehicle MC. And the approaching target can be detected without bias.

  Next, a shift process when the vehicle MC is traveling will be described with reference to FIG. The traveling state indicating that the own vehicle MC is traveling is, for example, a case where the traveling speed of the own vehicle MC exceeds a predetermined value (for example, zero).

  When the running state indicates that the host vehicle MC is running, the peak extracting unit 322a shifts the detection speed range so that the speed range in the approaching direction with respect to the host vehicle MC is widened.

  FIG. 6 shows a case where the shift amount of the detected speed range is different between when the host vehicle MC is at high speed and when it is at low speed. High speed means that the running speed is equal to or higher than a predetermined threshold, and low speed means that the running speed is lower than the predetermined threshold.

  The peak extracting unit 322a determines the shift amount of the detected speed range based on the traveling speed of the vehicle MC. For example, as shown in FIG. 6, the peak extracting unit 322a increases the shift amount of the detection speed range when the vehicle MC is traveling at a high speed, as compared with when traveling at a low speed.

  In other words, the peak extracting unit 322a shifts the relative speed on the approach side to a wider detection speed range at a high speed than at a low speed. This is because the higher the traveling speed, the lower the possibility that the target moves in the separating direction. That is, there is a low possibility that a target having a relative speed in the separating direction exists, and there is a high possibility that a peak will not be extracted even if the peak extraction processing is performed.

  As described above, when the traveling speed of the host vehicle MC is high, the detection speed range on the departure side where the peak is unlikely to be present is reduced, and the detection speed range on the approach side where the peak is likely to exist is increased. Thereby, the detection accuracy of the target can be improved.

  In other words, by increasing the detection speed range on the approach side and narrowing the detection speed range on the separation side, it is possible to prevent the relative speed on the approach side from being turned back and being erroneously detected as the relative speed on the separation side. At the same time, it can be correctly detected as a peak of the relative speed on the approach side.

  Note that, even when the host vehicle MC is running, it is preferable to perform a shift process different from that in FIG. FIG. 7 shows a shift process in a traveling state in which the host vehicle MC is traveling in a traffic jam. Note that the traveling state in which the host vehicle MC is traveling in congestion is, for example, a case where the traveling speed of the host vehicle MC is less than a predetermined threshold value and the distance from the preceding vehicle is continuously less than a predetermined value. It is. In other words, the traveling state in which the vehicle is traveling in traffic congestion is a traveling state when the vehicle is traveling at a low speed and the distance between the vehicles is relatively short.

  When the own vehicle MC is traveling in a traffic jam, the peak extracting unit 322a shifts the detected speed range so that the speed range in the separating direction is wider than the speed range in the approaching direction.

  This is because the traveling speed of the own vehicle MC and the other vehicle is extremely low during traffic congestion, and the approach speed of the following vehicle or the forward vehicle becomes relatively slow. This is because the detection accuracy of the approaching target can be maintained. Further, during traffic congestion, for example, in the case of an automatic following system, it is necessary to follow the preceding vehicle. Therefore, by increasing the detection speed range in the separating direction, the following performance of the preceding vehicle can be improved. .

  As described above, during traffic congestion, by widening the detection speed range on the departure side, for example, the following performance of the preceding vehicle in the automatic following system can be improved while maintaining the detection accuracy of the approaching target.

  As shown in FIGS. 6 and 7, when the vehicle MC is in a traveling state indicating that the vehicle MC is traveling (including traffic congestion), the peak extraction unit 322a moves away from or approaches the vehicle MC. The detected speed range is shifted so that the speed range in one of the directions is widened.

  Thereby, it is possible to set the detection speed range to be detected with priority according to the traveling state while maintaining the speed resolution. Note that the shift processing of the detection speed range shown in FIGS. 5 to 7 is an example, and the above-described shift amount and the like may be arbitrary values.

  The calculation unit 322b calculates the distance to the target, the relative speed, and the angle (azimuth) based on the peak extracted by the peak extraction unit 322a.

  Specifically, the calculation unit 322b derives the distance to the target and the relative speed based on a combination of the distance bin and the speed bin of the peak extracted by the peak extraction unit 322a.

  The calculation unit 322b estimates the angle of the target by a predetermined angle calculation process. Specifically, the calculation unit 322b estimates the angle of the target based on the phase difference between the peaks of the same distance bins of the frequency spectra of the four beat signals SB based on the reception signals SR of the four reception antennas 21a to 21d. . When it is detected that a plurality of targets exist in the same distance bin due to a difference in the phase of the peak of the same distance bin, the angle estimation is performed for each of the plurality of targets.

  Note that the angle estimation in the arithmetic unit 322b is performed using a predetermined estimation method such as ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques), DBF (Digital Beam Forming), or MUSIC (Multiple Signal Classification). .

  The output unit 322c outputs target information to the vehicle control device 2. For example, the output unit 322c outputs the detected distance, relative speed, and angle of the target to the vehicle control device 2 as target information.

  Next, a processing procedure of processing executed by the radar device 1 according to the embodiment will be described with reference to FIG. FIG. 8 is a flowchart illustrating a processing procedure of processing executed by the radar device 1.

  First, as illustrated in FIG. 8, the generation unit 321 performs frequency analysis on a beat signal obtained by mixing a frequency-modulated transmission wave (chirp wave) and a reflected wave of a transmission wave from a target. Thus, a two-dimensional frequency spectrum having a frequency axis corresponding to the distance and the relative speed of the target is generated (step S101).

  Subsequently, the detection unit 322 determines whether or not the traveling state of the vehicle MC is stopped (Step S102). If the traveling state indicates that the host vehicle MC is stopped (Step S102, Yes), the detection unit 322 sets the detection speed ranges in the separation direction and the approach direction to be the same (Step S103). The process ends.

  On the other hand, in step S102, when the traveling state indicates that the own vehicle MC is traveling (No in step S102), the detection unit 322 determines whether the traveling state is that the own vehicle MC is traveling in traffic. Is determined (step S104).

  When the own vehicle MC is traveling in a traffic jam (Step S104, Yes), the detection unit 322 sets a detection speed range wider on the departure side (positive side) than on the approach side (negative side) ( Step S105), the process ends.

  In addition, when the own vehicle MC is not in a traveling state in which the vehicle MC is traveling in a traffic jam, that is, in a traveling state indicating that the vehicle MC is traveling as usual (No in step S104), the detection unit 322 determines that the vehicle is approaching (negative side). ) Sets a detection speed range wider than the separation side (positive side) (step S106), and ends the processing.

  As described above, the radar device 1 according to the embodiment includes the generation unit 321 and the detection unit 322. The generation unit 321 performs frequency analysis on a beat signal obtained by mixing the frequency-modulated transmission wave and the reflected wave of the transmission wave from the target, thereby coping with the distance and relative speed of the target. Generate a two-dimensional frequency spectrum having a frequency axis. The detection unit 322 detects the distance and the relative speed of the target based on the peak extracted from the two-dimensional frequency spectrum generated by the generation unit 321. The detecting unit 322 shifts a predetermined speed range (detected speed range) corresponding to the frequency axis corresponding to the relative speed in the upper limit direction or the lower limit direction according to the traveling state of the vehicle MC. Thus, a desired detection speed range can be obtained with the speed resolution being fine.

  In the above-described embodiment, the case where the frequency of all of the plurality of chirp waves Ch of the transmission wave SW continuously increases (that is, up-chirp) is shown. However, for example, the frequency continuously decreases (that is, the frequency decreases). , Down-chirp) chirp wave Ch.

  Further, in the above-described embodiment, the case where the detection speed range for extracting the peak is shifted in the “peak selection processing” is described. However, the present invention is not limited to this. For example, the second (second dimension) in the “frequency analysis processing” may be used. The speed range of the FFT processing of ()) may be moved.

  Specifically, the generation unit 321 first performs the first FFT processing in the distance direction on the obtained beat signal. Subsequently, the generation unit 321 performs the second FFT processing in the relative speed direction on the result of the first FFT processing of each beat signal, thereby having a frequency axis corresponding to the distance and the relative speed of the target. Generate a dimensional frequency spectrum.

  At the time of the second FFT processing, the generation unit 321 shifts the speed range (speed bin range) in the relative speed direction in the second FFT processing. Specifically, in the second FFT process, the generation unit 321 shifts the speed range corresponding to the relative speed frequency axis in the upper limit direction or the lower limit direction according to the traveling state of the host vehicle MC.

  Then, the detection unit 322 detects the distance and the relative speed of the target based on the peak extracted from the two-dimensional frequency spectrum generated by the generation unit 321.

  As described above, the generation unit 321 can obtain a desired detection speed range while maintaining a state in which the speed resolution is fine, by shifting the speed range in which the FFT process is performed in the second FFT process. .

  Further effects and modifications can be easily derived by those skilled in the art. For this reason, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and equivalents thereof.

REFERENCE SIGNS LIST 1 radar device 2 vehicle control device 10 transmission unit 11 signal generation unit 12 oscillator 13 transmission antenna 20 reception unit 21, 21a to 21d reception antenna 22, 22a to 22d mixer 23, 23a to 23d A / D converter 30 processing unit 31 transmission Control unit 32 signal processing unit 33 storage unit 321 generation unit 322 detection unit 322a peak extraction unit 322b calculation unit 322c output unit 100 radar device MC vehicle P target S radar system

Claims (7)

By performing frequency analysis on a beat signal obtained by mixing a frequency-modulated transmission wave and a reflected wave of the transmission wave from the target, the frequency signal has a frequency axis corresponding to the distance and relative speed of the target. A generation unit that generates a two-dimensional frequency spectrum;
A detection unit that detects a distance and a relative speed of the target based on a peak extracted from the two-dimensional frequency spectrum generated by the generation unit,
The detection unit,
A target detecting device, wherein a predetermined speed range corresponding to a frequency axis corresponding to the relative speed is shifted in an upper limit direction or a lower limit direction according to a traveling state of the host vehicle. The detection unit,
When the traveling state indicates that the host vehicle is stopped, the predetermined speed range is shifted so that the speed ranges in the separating direction and the approaching direction with respect to the host vehicle are substantially the same. The target detection device according to claim 1, wherein: The detection unit,
When the traveling state indicates that the vehicle is traveling, the predetermined speed range is shifted such that one of the speed ranges in the separating direction or the approaching direction with respect to the vehicle is widened. The target detection device according to claim 1 or 2, wherein: The detection unit,
The target detection device according to claim 3, wherein the shift amount in the predetermined speed range is determined based on a traveling speed of the host vehicle. The detection unit,
When the traveling state indicates that the host vehicle is traveling in traffic, the predetermined speed range is shifted such that the speed range in the separating direction is wider than the speed range in the approaching direction. The target detection device according to claim 3 or 4, wherein: The first FFT processing in the distance direction is performed on a beat signal obtained by mixing the frequency-modulated transmission wave and the reflected wave of the transmission wave from the target, and the result of the first FFT processing is performed. Performing a second FFT process in the relative velocity direction to generate a two-dimensional frequency spectrum having a frequency axis corresponding to the distance and the relative velocity of the target;
A detection unit that detects a distance and a relative speed of the target based on a peak extracted from the two-dimensional frequency spectrum generated by the generation unit,
The generation unit includes:
In the second FFT processing, a predetermined speed range corresponding to a frequency axis corresponding to the relative speed is shifted in an upper limit direction or a lower limit direction according to a traveling state of the host vehicle. . By performing frequency analysis on a beat signal obtained by mixing a frequency-modulated transmission wave and a reflected wave of the transmission wave from the target, the frequency signal has a frequency axis corresponding to the distance and relative speed of the target. Generating a two-dimensional frequency spectrum;
A detecting step of detecting a distance and a relative speed of the target based on a peak extracted from the two-dimensional frequency spectrum generated by the generating step,
The detecting step includes:
A target detection method, wherein a predetermined speed range corresponding to a frequency axis corresponding to the relative speed is shifted in an upper limit direction or a lower limit direction according to a traveling state of the host vehicle.