JP7622479B2 - Radar device and control method thereof - Google Patents

Description

The present invention relates to a radar device using, for example, a millimeter wave sensor, and a control method thereof.

Conventionally, abnormal conditions in the radar device, such as interference with the radar device or a malfunction of the radar device, were detected by monitoring the time fluctuation of the noise level.

For example, Patent Document 1 discloses a radar device having the following configuration for detecting and reporting ice, snow, and dirt on the radome without installing sensors or the like in the radome of the radar device. This radar device is an FM radar device that transmits a frequency-swept FM signal, receives a reflected signal from the object, and detects the position of the object from the frequency of a beat signal obtained by mixing the reflected signal with a portion of the transmitted signal, and is characterized by having a means for detecting dirt on the antenna radome based on the level of the low-frequency component of the beat signal.

Patent Document 2 also discloses an on-vehicle radar device having the following configuration for detecting dirt without reducing the time resolution of target detection. The radar device detects objects around the vehicle, and the detection range includes the road surface. The signal processing unit uses beat frequencies that exceed a second threshold to detect the objects around the vehicle, and determines that dirt is present in the transmitting unit or receiving unit when the number of occurrences of beat frequencies with reception levels exceeding a first threshold in a predetermined frequency range within a predetermined time period is equal to or less than a predetermined value.

Japanese Patent Application Publication No. 10-282229 JP 2000-019242 A

However, in these conventional radar devices, when calculating the reference noise level, it was necessary to do so in an ideal environment with little ambient reflection (such as an anechoic chamber or an open outdoor space) in order to minimize the effects of multipath from stationary objects and the ground. In addition, because the noise level fluctuates due to factors such as device heat, a separate measure was required to constantly monitor the device temperature.

The object of the present invention is to solve the above problems and provide a radar device and a control method thereof that can detect an abnormal state of the radar device in a simpler manner and in a shorter time than conventional techniques.

The radar device according to the present invention comprises:
A radar device comprising: a radio transmitting unit that transmits a radio signal including a transmission chirp signal; and a radio receiving unit that receives a radio signal including the reflected reception chirp signal after the radio signal including the transmission chirp signal is reflected by a target,
The wireless receiving unit includes:
Detecting a beat signal by mixing the received radio signal including the received chirp signal with the radio signal including the transmitted chirp signal;
band-pass filtering the beat signal with a predetermined passband width or low-pass filtering with a predetermined lower cutoff frequency;
performing two-dimensional FFT processing of distance and relative velocity on the filtered beat signal to calculate map information including distance spectra for a plurality of relative velocities;
determining a frequency range of distance and relative speed that is a blind spot range of the radar device based on the map information, and calculating an average value of the signal strength of the received wireless signal from the determined frequency range;
The calculated signal strength is compared with a predetermined abnormality detection threshold to determine whether or not the radar device is in an abnormal state.

Therefore, the radar device according to the present invention can detect an abnormal state of the radar device in a simpler manner and in a shorter time than the conventional technology.

1 is a block diagram showing an example of the configuration of a radar device 100 according to an embodiment. 2 is a graph showing a frequency change waveform of a chirp signal used in the radar device 100 of FIG. 1 . 2 is a diagram showing gain frequency characteristics of bandpass filters 24-1 to 24-N used in the radar device 100 of FIG. 1. 4 is a plan view showing the positional relationship between a radar device 100 installed on a road 400 and a vehicle 310 traveling on a traffic lane 411. 1 is a side view showing the positional relationship between a radar device 100 installed on a road 400 and a vehicle 310 traveling on the ground 300 of the road 400. FIG. 2 is a diagram showing a distance spectrum and an RV map (a map in which the distance and speed of a vehicle are mapped) calculated by the radar device 100 of FIG. 1. FIG. 2 is a diagram showing the relationship between the RV map calculated by the radar device 100 of FIG. 1 and power. 2 is a flowchart showing a pre-processing before reception executed by the radar device 100 of FIG. 1 . 2 is a flowchart showing a received signal process executed by the radar device 100 of FIG. 1 .

Below, an embodiment of a radar device using, for example, the FCM method and a control method thereof according to the embodiment will be described with reference to the attached drawings. Note that the present invention is not limited to this embodiment.

(Embodiment)
1 is a block diagram showing an example of the configuration of a radar device 100 according to an embodiment. The example of the configuration of the radar device 100 will be described below.

In order to solve the above-mentioned problems, the radar device 100 according to the embodiment of the present invention includes a pre-processing unit 4 and anomaly detection units 32-1 to 32-N (collectively denoted by the reference symbol 32).
(A) The pre-processing unit 4 determines a frequency range (a frequency range indicating the relationship between distance and relative speed) that corresponds to the blind spots 51, 52 (meaning a range that cannot be detected by the radar device 100; see FIG. 6 ) of the radar device 100 based on information on the installation position of the radar device 100, calculates an average value of the signal strength based on the frequency range, and calculates an anomaly detection threshold value based on the average value of the signal strength.
(B) The abnormality detection unit 32 detects an “abnormal state” by performing two-dimensional FFT (Fast Fourier Transformation) processing on each beat signal for each reception signal received by a plurality of antennas 21-1 to 21-N (collectively referred to as 21) and comparing the average value of the signal strength after the processing with the abnormality detection threshold value.

The following describes the radar device 100 according to the embodiment and the modified examples. Note that the following embodiment and the modified examples are merely examples and are one embodiment of the present invention, and are not limited to these.

In FIG. 1, the radar device 100 estimates the distance and relative speed of a target using, for example, the FCM (Fast Chirp Modulation) method. In the FCM method, a transmission chirp signal, which is a repeat of multiple chirp signals whose frequency changes continuously, is wirelessly transmitted to the target to detect the distance and relative speed of each target present within the detection range. Specifically, the FCM method estimates the distance and relative speed of the target by performing two-dimensional fast Fourier transform processing (hereinafter referred to as two-dimensional FFT processing) on a beat signal b(t) generated from a modulated signal that generates a chirp signal St and a received signal obtained by receiving a reflected wave of the transmission signal by the target. Note that the two-dimensional FFT processing includes two FFT processes, a distance FFT process and a speed FFT process.

Figure 2A is a graph showing a frequency change waveform diagram of the chirp signal used in the radar device 100 of Figure 1. As shown in Figure 2A, the chirp signal increases over time with a chirp gradient Δf (Hz/s).

The maximum detectable distance R _max and maximum detectable speed V _max of the radar device 100 when using the chirp signal of FIG. 2A are expressed by the following equations, as is well known.

Here, fs is the sampling rate, c is the speed of light (a fixed value of 299792458), S is the slope of the chirp signal, B is the occupied bandwidth of the radar signal, λ is the wavelength of the radar signal, and Tc is the period of the chirp signal (=occupied bandwidth B/slope of the chirp signal S).

Figure 2B is a diagram showing the gain frequency characteristics of bandpass filters 24-1 to 24-N (collectively designated by the reference symbol 24) used in the radar device 100 of Figure 1. As shown in Figure 2B, the gain of bandpass filter 24 has a frequency characteristic in which, for example, it rises from gain Gmin, has a maximum gain Gmax at the normalized lower limit frequency fmin of the passband, and after maintaining the maximum gain Gmax within the passband, it drops from the normalized upper limit frequency fmax to a predetermined frequency fm. In other words, bandpass filter 24 has a predetermined passband width that passes the main component of beat signal b(t). Note that, instead of each bandpass filter 24, a lowpass filter having a predetermined lower cutoff frequency and passing the main component of beat signal b(t) may be used.

In FIG. 1, the radar device 100 includes a wireless transmitter 1, a wireless receiver 2, and a signal processor 3. Here, the wireless transmitter 1 includes a transmission controller 10, a modulated signal generator 11, an oscillator 12, a power amplifier 13, and a transmission antenna 14. The wireless receiver 2 includes one or more N receiving antennas 21-1 to 21-N (hereinafter collectively referred to as 21), a plurality of N low noise amplifiers 22-1 to 22-N (hereinafter collectively referred to as 22), a plurality of N mixers 23-1 to 23-N (hereinafter collectively referred to as 23), a plurality of N band pass filters (BPFs) 24, and a plurality of N AD converters (ADCs) 25-1 to 25-N (hereinafter collectively referred to as 25).

The signal processing unit 3 further includes a pre-processing unit 4, a plurality of N distance and speed estimation units 31-1 to 31-N (hereinafter collectively referred to as 31), a plurality of N anomaly detection units 32-1 to 32-N (hereinafter collectively referred to as 32), an arrival angle estimation unit 33, and a display unit 34. Here, each anomaly detection unit 32 includes anomaly detection threshold memory 321m, 322m, 323m, ..., 32Nm that stores anomaly detection thresholds.

The pre-processing unit 4 also includes an information input unit 41, a blind spot range calculation unit 42, and an abnormality detection threshold calculation unit 43. The pre-processing unit 4 executes the pre-processing shown in FIG. 5, which will be described later, before transmitting the radar signal. Here, the user inputs information on the installation location of the radar device 100 using the information input unit 41. Next, the blind spot range calculation unit 42 determines the frequency range (frequency range showing the relationship between distance and relative speed) that will be the blind spot ranges 51, 52 (see FIG. 6) based on the input information on the installation location of the radar device 100. Furthermore, the abnormality detection threshold calculation unit 43 calculates the average value of the signal strength based on the determined frequency range, calculates the abnormality detection threshold based on the average value of the signal strength, and stores and memorizes it in the abnormality detection threshold memory 321m to 32Nm in each abnormality detection unit 32.

The transmission control unit 10 of the wireless transmitting unit 1 generates a transmission interval signal Si having a predetermined transmission interval _Tn and outputs it to the modulating signal generating unit 11. The modulating signal generating unit 11 generates a modulating signal (chirp signal) whose frequency changes in a triangular wave shape such as a sawtooth wave shape shown in FIG. 2A, and outputs it to the oscillator 12. The oscillator 12 generates a wireless signal St including a transmission chirp signal having the transmission interval Tn in accordance with the modulating signal, and outputs it to the transmitting antenna 14 via the power amplifier 13, and the wireless signal including the transmission chirp signal St is radiated from the transmitting antenna 14 toward a target (object). The wireless signal St including the transmission chirp signal from the oscillator 12 is also distributed to the mixer 23 of the wireless receiving unit 2.

In the radio receiving unit 2, the N receiving antennas 21 constituting the array antenna receive the radio signal St including the transmitted chirp signal, which is a reflected wave from a target that is a reflector, as a radio signal Sr including the received chirp signal, and output the radio signal Sr to the mixer 23 via the low noise amplifier 22. Each mixer 23 mixes the radio signal Sr including the received chirp signal contained in the radio signal from each low noise amplifier 22 with the radio signal St including the transmitted chirp signal from the oscillator 12, and outputs the result to each band pass filter 24. Each band pass filter 24 performs filtering with the band pass characteristics of FIG. 2B described above, thereby detecting a beat signal b(t) having a beat frequency and outputting it to each AD converter 25. Each AD converter 25 AD converts the input beat signal b(t) into a digital beat signal and outputs it to each distance and speed estimation unit 31 of the signal processing unit 3.

The number N of the receiving antennas 21, etc. shown in FIG. 1 is, for example, 1 or more. In this embodiment, distance estimation or speed estimation is possible with one receiving antenna 21, but if the arrival angle is also to be estimated, two or more receiving antennas 21 are required.

The signal processing unit 30 is composed of a microcomputer including, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), input/output ports, etc., and controls the entire radar device 100.

Each distance and speed estimation unit 31 performs known two-dimensional FFT processing (distance FFT processing and speed FFT processing) on the beat signal b(t) output from each AD converter 25, calculates the distance and relative speed of the target based on the results of the two-dimensional FFT processing, and outputs them to the anomaly detection unit 32.

Each anomaly detection unit 32 performs two-dimensional FFT processing on each beat signal b(t) for each received signal received by a plurality of antennas 21-1 to 21-N (collectively referred to as 21), and compares the average value of the signal strength after processing with the anomaly detection threshold stored in the anomaly detection threshold memory 321m to 32Nm to detect whether or not there is an "abnormal state", and outputs the detection result to the display unit 34 for display, as well as to the arrival angle estimation unit 33. Details of the anomaly detection processing in the anomaly detection unit 32 will be described in detail later.

The arrival angle estimation unit 33 estimates the arrival angle of the target by a predetermined known arrival angle calculation process based on the radio signal Sr including multiple received chirp signals or the beat signal b(t) generated based on the same. For example, each arrival angle estimation unit 33 estimates the arrival angle of the target based on the difference in phase of the peaks of the same distance bin of each of the frequency spectra of the multiple beat signals b(t) based on the multiple received signals received by the receiving antenna 21. Note that when the presence of multiple targets (reflectors) in the same distance bin is detected due to the difference in the phase of the peaks of the same distance bin, angle estimation is performed for each of the multiple targets. The angle estimation in the arrival angle estimation unit 33 is performed using a known estimation method such as ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques), DBF (Digital Beam Forming), or MUSIC (Multiple Signal Classification).

The arrival angle estimation unit 33 outputs information related to the distance and relative speed to the target estimated by each distance and speed estimation unit 31, in addition to the calculated arrival angle of the radio signal reflected by the target, to the other control device 200. In FIG. 1, the other control device 200 is another radar device, or a control device that comprehensively controls the radar device 100 and the other radar devices.

Next, the details of the anomaly detection process performed by the anomaly detection unit 32 are described below.

Figure 3 is a plan view showing the positional relationship between the radar device 100 installed on the road 400 and a vehicle 310 traveling on a traffic lane 411. Also, Figure 4 is a side view showing the positional relationship between the radar device 100 installed on the road 400 and a vehicle 310 traveling on the ground 300 of the road 400.

In FIG. 3, the road 400 has a driving lane 411 between the center line 401 and the shoulder 402, and a driving lane 423 between the center line 401 and the shoulder 403. Here, a vehicle 310 travels in the driving lane 411 at a speed V, and the radar device 100 is installed on the driving lane 412, near the shoulder 403. Also, the radar signal from the radar device 100 is reflected at a reflection point Rp on the upper part of the windshield. Furthermore, in FIG. 4, the radar device 100 is installed at a height H from the ground 300 of the road 400, and the vehicle 310 has a vehicle height h.

Here, in the horizontal plane of Fig. 3, the installation coordinates of the radar device 100 are [0,0], and the reflection point coordinates on the vehicle 310 are [x,y]. In addition, in the vertical plane of Fig. 4, the installation coordinates of the radar device 100 are [0,0], and the reflection point coordinates on the vehicle 310 are [x,H-y]. In this case, the relative speed V _R (φ,θ) from the radar device 100 is expressed by the following equation.

Here, the horizontal angle φ and vertical angle θ are expressed by the following equations.

Figure 5 shows the distance spectrum and RV map (a map that maps the distance and speed of a vehicle) calculated by the radar device 100 of Figure 1, and Figure 6 shows the relationship between the RV map and power calculated by the radar device 100 of Figure 1. Here, the abnormality detection process according to this embodiment is characterized in that blind spot ranges 51 and 52 in Figure 6 are set for specific distance and speed bins.

Each distance and speed estimation unit 31 performs known two-dimensional FFT processing (distance FFT processing and speed FFT processing) on the beat signal b(t) output from each AD converter 25, and calculates the distance and relative speed of the target based on the results of the two-dimensional FFT processing. Here, the calculated distance and relative speed of the target are calculated by calculating a spectrum for the distance bin for each speed bin number, as shown in Figure 5, and the calculated multiple spectra are calculated as an RV map (a map of distance R and speed V).

The blind spot ranges 51 and 52 are calculated by the blind spot range calculation unit 42, are illustrated in the RV map, and are defined as follows:
(A) Blind spot range 51: range of distance bin numbers 1 to m and speed bins 1 to n;
(B) Blind spot range 52: Range of distance bin numbers 1 to m and speed bin numbers (N−n−1) to N.

Here, the parameters used in the anomaly detection process are as follows:

(1) Maximum detection distance R _max [m] (see the above formula)
(2) Maximum detectable speed ±V _max [km/h] (see the formula above)
(3) Number of distance bins M [bin]
(4) Number of speed bins N [bin]
(5) Installation height H [m] of the radar device 100 (see FIG. 4)
(6) Height limit for large vehicles h _lim [m] (for example, about 3.8 to 4.1 m)
(7) Margin distance bin m [bin] (e.g., about 5 to 10)

(8) The margin distance R _margin [m] is expressed by the following equation.

However, R _margin >Hh (see FIG. 4).

(9) The margin speed bin n [bin] (where n is an integer) is expressed by the following formula:

(10) The margin speed V _margin [km/h] is expressed by the following equation.

(11) The maximum detection distance R _max is expressed as described above with reference to FIG. 2A.

(12) The maximum detectable velocity ±V _max is expressed as described above with reference to FIG. 2A.

Next, we will explain the thresholds used for anomaly detection.

は次式で表される。 (1) Average signal strength of blind spots 51 and 52

is expressed by the following equation.

Here, r is the distance index, v is the velocity index, and |S(v;r) is the normal amplitude spectrum.

(2) The abnormality detection threshold S _TH is expressed by the following equation.

Here, α is a value between 3 and 5.

Furthermore, the results of anomaly detection based on threshold judgment for each frame are explained below.

The result of anomaly detection based on threshold judgment for each frame is expressed by the following formula.

は次式で表される。 Therefore, the average signal strength of the blind spots 51 and 52

is expressed by the following equation.

where t is the frame index and |Q(t;v;r)| is the amplitude spectrum to be evaluated.

Figure 7 is a flowchart showing the pre-reception pre-processing executed by the pre-processing unit 4 of the radar device 100 in Figure 1.

を計算し、計算された死角範囲５１，５２の信号強度の平均値

に基づいて、異常検出用閾値Ｓｔｈを計算し、異常検出部３２－１～３２－Ｎの各閾値メモリ３２１ｍ～３２Ｎｍに格納して記憶させ、当該全理処理を終了する。 7, the user inputs information on the installation location of the radar device 100 using the information input unit 41, and in step S2, the blind spot range calculation unit 42 calculates blind spot ranges 51, 52 (frequency ranges indicating specific distances and speeds) based on the input information on the installation location of the radar device 100. Next, in step S3, the abnormality detection threshold calculation unit 43 calculates the average value of the signal strength of the blind spot ranges 51, 52 based on the calculated blind spot ranges 51, 52.

The average value of the signal strength of the calculated blind spots 51 and 52 is calculated.

The abnormality detection threshold value Sth is calculated based on the above, and is stored in the threshold value memories 321m to 32Nm of the abnormality detection units 32-1 to 32-N, and the overall processing ends.

Figure 8 is a flowchart showing the received signal processing performed by the radar device 100 of Figure 1.

In step S11 of FIG. 8, a radio signal including a chirp signal is transmitted from the radio transmitting unit 1, and the radio receiving unit 2 receives the radio signal including the chirp signal. Next, in step S12, the transmitted chirp signal and the received chirp signal are mixed, band-pass filtered by the band-pass filter 24, and AD converted by the AD converter 25 to generate each beat signal. Furthermore, in step S13, the distance and velocity estimation unit 31 performs two-dimensional FFT processing of the distance and Doppler velocity for each beat signal.

を算出し、閾値判定により、異常検出を行い、ステップＳ１５において、異常を検出したか否かが判断される。ステップＳ１５でＹＥＳのときはステップＳ１６に進む一方、ＮＯのときはステップＳ１７に進む。ステップＳ１６において、「異常状態の検出」を表示部３４に表示し、当該受信信号処理を終了する。一方、ステップＳ１７では、異常状態を検出しないと判断し、到来角度推定部３３は、各受信アンテナの位相差から到来角度を推定し、推定した到来角度を表示部３４に表示し、当該受信信号処理を終了する。 Next, in step S14, the abnormality detection unit 32 calculates the average value of the signal strength in the blind spots 51 and 52.

is calculated, abnormality detection is performed by threshold judgment, and in step S15, it is judged whether or not an abnormality has been detected. If the answer is YES in step S15, the process proceeds to step S16, whereas if the answer is NO, the process proceeds to step S17. In step S16, "abnormal state detected" is displayed on the display unit 34, and the received signal processing is terminated. On the other hand, in step S17, it is judged that an abnormal state has not been detected, and the arrival angle estimation unit 33 estimates the arrival angle from the phase difference of each receiving antenna, displays the estimated arrival angle on the display unit 34, and the received signal processing is terminated.

The inventors performed a simulation of the radar device 100 in FIG. 1. The results are described in Examples 1 and 2 below.

In Example 1, the parameters and calculation results for an example in which the assumed target is an automobile are shown in Table 1 below.

[Table 1]
――――――――――――――――――――――――――――――――
Maximum detection distance R _max = 200 [m]
Maximum detectable speed ±V _max =70 [km/h]
Distance bin number M = 512 [bin]
Number of speed bins N = 512 [bin]
Radar equipment installation height H = 6 [m]
(Assuming installation near traffic lights, traffic signs, and road guide signs)
Height limit for large vehicles h _lim = 4.1 [m]
(H-h _lim = 1.9m)
Margin distance bin number m = 10 [bin]
Margin distance R _margin = 3.9 [m]
Margin speed bin number n = 32 [bin]
Margin speed V _margin = ±8.75 [km/h]
(-70 to -61.25, 61.25 to 70 [km/h])
Target vehicle's running position x = 5.00 m
Target vehicle running position y = 1.75 m
Height of target vehicle h = 2.30 m (H-h = 3.70 m)
(As an example of a particularly large passenger vehicle, the values of the Toyota Hiace Wagon Grand Cabin (registered trademark) are used as a reference example.)
Horizontal angle φ = 19.29 degrees Vertical angle θ = 36.50 degrees Speed of target vehicle V = 60.00 [km/h]
The relative speed from the radar device at this time is V _R (φ, θ)=45.52 [km/h]
――――――――――――――――――――――――――――――――

As is clear from Table 1, it is possible to sufficiently separate the frequency range used for anomaly detection and the distance/speed of the target object.

In Example 2, the parameters and calculation results for an example in which the assumed target is a pedestrian or a bicycle are shown in Table 2 below.

[Table 2]
――――――――――――――――――――――――――――――――
Maximum detection distance R _max = 100 [m]
Maximum detectable speed ±V _max = 40 [km/h]
Distance bin number M = 512 [bin]
Number of speed bins N = 512 [bin]
Radar device installation height H = 3 [m] (assuming installation near street lights, etc.)
Maximum height of pedestrians and bicycles h _lim = 2 [m] (H-h _lim = 1 m)
Margin distance bin number m = 10 [bin]
Margin distance R _margin = 1.95 [m]
Margin speed bin number n = 36 [bin]
Margin speed V _margin = ±5.625 [km/h]
(-40 to -34.375, 34.375 to 40 [km/h])
Position of object x = 1m
Position of object y = 0m
Height of object h = 1.7 m (H-h = 1.30 m)
Horizontal angle φ = 0 degrees Vertical angle θ = 52.43 degrees Speed of object V = 40.00 [km/h]
Relative speed from the radar device V _R (φ, θ) = 24.39 [km/h]
(Note) The subject was assumed to be "bicycles (especially road bikes)."
――――――――――――――――――――――――――――――――

As is clear from Table 2, it is possible to sufficiently separate the frequency range used for anomaly detection and the distance/speed of the target object.

As described above, according to this embodiment, it is possible to detect an abnormal state of the radar device, such as interference with the radar device or a failure of the radar device, in a simpler manner and in a shorter time than with conventional technology.

The radar device 100 according to this embodiment differs from vehicle-mounted radars in that infrastructure radar devices (particularly for road monitoring applications) make effective use of the installation condition that targets, particularly moving objects, are not necessarily directly in the line of sight of the radar. This means that the closer the target is to the radar, the steeper the angle at which it is positioned, and the greater the change in its relative speed with respect to the line of sight of the radar.

The radar device 100 according to this embodiment can be applied to the detection of abnormal operation in, for example, infrastructure radar devices (FCM modulation, FMCW modulation, pulse compression modulation) equipped with a millimeter wave sensor. In particular, it can be used as a technical means for realizing abnormality detection in millimeter wave radar devices for road monitoring. As an application, the radar device can be attached to traffic lights and traffic signs to detect the position and speed of vehicles and perform traffic counters to ease congestion. Here, when a user obtains distance, relative speed, and direction information of a reflecting object, the user can determine whether the information is normal or abnormal, which leads to a reduction in the occurrence of traffic accidents.

In addition, the radar device 100 according to this embodiment can increase the processing speed, making it possible to determine whether or not a constant false alarm rate (CFAR) is required as pre-processing for detecting targets, thereby reducing the number of CFARs. In other words, the radar device has the unique effect of eliminating the need for CFAR for all distance and relative velocity bins, i.e., eliminating the need for two-dimensional CFAR.

(Modification)
In the above embodiment, the transmission chirp signal has been described as having a continuously increasing frequency (i.e., an up-chirp), but it may be a chirp signal having a continuously decreasing frequency (i.e., a down-chirp), or a combination thereof.

In the above embodiment, a radar device using the FCM method has been described, but the present invention is not limited to this and can be applied to radar devices using the FMCW modulation method or the pulse compression modulation method.

In the above embodiment, the position and relative velocity of the target are estimated, but the present invention is not limited to this, and may be configured to estimate only the relative velocity of the target.

Further advantages and modifications to the above embodiments may be readily derived by those skilled in the art. Therefore, the invention in its broader aspects is 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.

(Differences between this embodiment and Patent Document 1)
In this embodiment, two-dimensional FFT processing (distance FFT processing and velocity FFT processing) is performed on the beat signal, and the frequency range (distance and relative velocity) of the blind spot is determined from the installation position information. Next, the average value of the signal strength is calculated from the frequency range of the blind spot, and anomaly detection is performed by threshold judgment.

In contrast, in Patent Document 1, distance FFT processing is performed on the beat signal, the average value of the signal strength in the short distance range is calculated, and anomalies (dirt on the radome) are detected by threshold judgment. Next, the distance and direction to the target are calculated and output from the results of angle FFT processing.

(Differences between this embodiment and Patent Document 2)
In this embodiment, two-dimensional FFT processing (distance FFT processing and velocity FFT processing) is performed on the beat signal, and the frequency range (distance and relative velocity) of the blind spot is determined from the installation position information. Next, the average value of the signal strength is calculated from the frequency range of the blind spot, and anomaly detection is performed by threshold judgment.

In response to this, in Patent Document 1, two-dimensional FFT processing (distance FFT processing and speed FFT processing) is performed on the beat signal, and the frequency (distance) range of the road surface reflection signal is determined from the vehicle speed and road surface reflection distance. Next, the signal strength and duration of the road surface reflection are judged based on thresholds to detect abnormalities (antenna dirt). Then, the distance to the target, the relative speed, and the direction are calculated and output based on the results of the angle FFT processing.

As described above in detail, the radar device and control method of the present invention can detect an abnormal state of the radar device in a simpler manner and in a shorter time than conventional techniques.

The radar device according to the present invention can be applied as a technical means for implementing interference countermeasures, for example, in millimeter wave radar for road monitoring. Applications include attaching the radar device to traffic signals and traffic signs to detect the position and speed of vehicles and perform traffic counters to ease congestion. The present invention can also be applied to the interference detection function of radar devices (FCM modulation type, FMCW modulation type, pulse compression modulation type) equipped with millimeter wave sensors, and can be applied to long-range radar for weather, marine, and aircraft applications, for example.

1 Radio transmitter 2 Radio receiver 3 Signal processor 4 Pre-processor 10 Transmission controller 11 Modulated signal generator 12 Oscillator 13 Power amplifier 14 Transmitting antennas 21, 21-1 to 21-N Receiving antennas 22, 22-1 to 22-N Low noise amplifiers 23, 23-1 to 23-N Mixers 24, 24-1 to 24-N Bandpass filters (BPFs)
25, 25-1 to 25-N Analog-to-digital converter (ADC)
31, 31-1 to 31-N Distance and speed estimation unit 32, 32-1 to 32-N Abnormality detection unit 321m, 322m, 323m to 32Nm Abnormality detection threshold memory 33 Arrival angle estimation unit 34 Display unit 41 Information input unit 42 Blind spot range calculation unit 43 Abnormality detection threshold calculation units 51, 52 Blind spot range 100 Radar device 200 Other control device 300 Ground 310 Vehicle 400 Road 401 Center line 402, 403 Roadside strip 411, 412 Travel lane

Claims (8)

A radar device comprising: a radio transmitting unit that transmits a radio signal including a transmission chirp signal; and a radio receiving unit that receives a radio signal including the reflected reception chirp signal after the radio signal including the transmission chirp signal is reflected by a target,
The wireless receiving unit includes:
Calculating a blind spot range of the radar device based on installation information of the radar device;
Detecting a beat signal by mixing the received radio signal including the received chirp signal with the radio signal including the transmitted chirp signal;
band-pass filtering the beat signal with a predetermined passband width or low-pass filtering with a predetermined lower cutoff frequency;
performing two-dimensional FFT processing of distance and relative velocity on the filtered beat signal to calculate map information including distance spectra for a plurality of relative velocities;
determining a frequency range of distance and relative speed that is a blind spot range of the radar device based on the map information, and calculating an average value of the signal strength of the received wireless signal from the determined frequency range;
The calculated signal strength is compared with a predetermined abnormality detection threshold to determine whether the radar device is in an abnormal state.
Radar equipment. the wireless receiving unit calculates an average value of signal strength in the blind spot range based on the calculated blind spot range of the radar device, and calculates an anomaly detection threshold value based on the calculated average value of signal strength.
The radar device according to claim 1 . the wireless receiving unit receives a plurality of wireless signals each including a received chirp signal when the radar device is not in an abnormal state, and estimates an arrival angle of the target based on the received plurality of wireless signals;
3. A radar device according to claim 1 or 2 . The transmit chirp signal has a continuously varying frequency.
The radar device according to any one of claims 1 to 3 . A method for controlling a radar device including a radio transmitting unit that transmits a radio signal including a transmission chirp signal, and a radio receiving unit that receives a radio signal including the reflected reception chirp signal after the radio signal including the transmission chirp signal is reflected by a target, comprising:
The wireless receiving unit,
calculating a blind spot range of the radar device based on installation information of the radar device;
detecting a beat signal by mixing the received radio signal including the received chirp signal with the radio signal including the transmitted chirp signal;
band-pass filtering the beat signal with a predetermined passband width or low-pass filtering with a predetermined lower cutoff frequency;
performing a two-dimensional FFT process of distance and relative velocity on the filtered beat signal to calculate map information including distance spectra for a plurality of relative velocities;
determining a frequency range of distance and relative speed that is a blind spot range of the radar device based on the map information, and calculating an average value of the signal strength of the received wireless signal from the determined frequency range;
determining whether the radar device is in an abnormal state by comparing the calculated signal strength with a predetermined abnormality detection threshold;
Further comprising:
A method for controlling a radar device. the wireless receiving unit calculates an average value of signal strength in the blind spot range based on the calculated blind spot range of the radar device, and calculates an anomaly detection threshold value based on the calculated average value of signal strength.
A method for controlling a radar device according to claim 5 . The method further includes a step of receiving a plurality of radio signals each including a received chirp signal by the radio receiving unit when the radar device is not in an abnormal state, and estimating an arrival angle of the target based on the received plurality of radio signals.
A method for controlling a radar device according to claim 5 or 6 . The transmit chirp signal has a continuously varying frequency.
A method for controlling a radar device according to any one of claims 5 to 7 .

Images