radar equipment

Abstract

A processing unit 6 for detecting each object that reflects radar waves comprises a wavenumber calculating unit 82, a wavenumber evaluation value calculating unit 84, a false azimuth evaluation value calculating unit 86, and a dirt determining unit 88. The wavenumber calculating unit calculates a wavenumber of a reflected incoming wave for each object, and the wavenumber evaluation value calculating unit calculates the proportion of all the objects that is accounted for by objects having a plurality of wavenumbers. The false azimuth evaluation value calculating unit calculates the proportion of the objects having a plurality of wavenumbers that is accounted for by objects having a second incoming wave of which an azimuth difference, relative to the azimuth of a first incoming wave having maximum electric power, is a specific azimuth difference. The dirt determining unit determines a dirty radome on the basis of the wavenumber evaluation value and the false azimuth evaluation value calculated by the calculating units.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This international application claims priority based on Japanese Patent Application No. 2021-144783 filed with the Japan Patent Office on September 6, 2021, and the entire contents of Japanese Patent Application No. 2021-144783 are incorporated by reference into this international application. [Technical field]

[0002] The present disclosure relates to a radar device that detects targets by transmitting and receiving radio waves via multiple antennas. [Background technology]

[0003] Patent Document 1 describes detecting dirt on a radome that covers the apertures of multiple antennas to protect the antenna units in a radar device.

[0004] In this radar device, the number of incoming waves caused by the transmitted radio waves hitting the target and being reflected is calculated for each detected target, and if the proportion of targets with multiple incoming wave numbers is equal to or greater than a predetermined proportion, the radome is judged to be dirty. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5978754 Summary of the Invention

[0006] However, as a result of detailed study by the inventors, it was found that if the degree of contamination on the radome is judged only based on the proportion of targets with multiple incoming waves to the total number of targets, as described above, there is a problem that the degree of contamination may be erroneously judged due to an error in calculating the proportion, etc.

[0007] An aspect of the present disclosure aims to enable a radar device, particularly a MIMO radar, to more accurately determine contamination of an antenna radome from the number of waves arriving from a detected target.

[0008] A radar device according to an aspect of the present disclosure includes a transmitting antenna unit, an oscillator unit, a modulator unit, a receiving antenna unit, a processor unit, and a radome.

[0009] The transmitting antenna section has a plurality of transmitting antennas, and the receiving antenna section has a plurality of receiving antennas. The oscillating section generates a continuous wave common signal. The modulating section performs a predetermined modulation on each of a plurality of branch signals obtained by branching the common signal generated by the oscillating section into the same number of transmitting antennas, thereby generating a plurality of transmission signals to be input to the plurality of transmitting antennas. Therefore, radio waves are radiated from the plurality of transmitting antennas by the transmission signals generated by the modulating section.

[0010] The processing unit is configured to detect each of the targets that have reflected the transmission waves from the transmitting antenna unit, based on a plurality of signal components corresponding to the plurality of transmission signals extracted from each of the plurality of reception signals received by the receiving antenna unit. The radome covers and protects the opening faces of the plurality of transmission antennas and the plurality of receiving antennas.

[0011] In the radar device of the present disclosure, a virtual array having a plurality of virtual receiving antennas is formed by a plurality of transmitting antennas and a plurality of receiving antennas. Therefore, the radar device of the present disclosure is a MIMO radar. MIMO is an abbreviation for Multi Input Multi Output.

[0012] Next, the processing unit includes a wave number calculation unit, a wave number evaluation value calculation unit, a false orientation evaluation value calculation unit, and a dirt determination unit.

[0013] The wave number calculation unit calculates the wave number of the incoming waves reflected from each target object detected by the processing unit.

[0014] The wave number evaluation value calculation unit calculates, as a wave number evaluation value, the proportion of targets having a plurality of wave numbers calculated by the wave number calculation unit among all targets detected by the processing unit.

[0015] The false heading evaluation value calculation unit calculates, as a false heading evaluation value, the proportion of targets including a second arriving wave whose heading difference is a specific heading difference caused by a periodic signal error being superimposed on the virtual array, relative to the heading of a first arriving wave whose power of the arriving wave is maximum, among targets having multiple wave numbers calculated by the wave number calculation unit.

[0016] Then, the contamination determination unit determines the contamination of the radome based on the wave number evaluation value and the false orientation evaluation value.

[0017] In this manner, in the radar device of the present disclosure, in order to judge the contamination of the radome, a false azimuth evaluation value is used in addition to a wave number evaluation value, which is the proportion of targets with multiple wave numbers of incoming waves from the target among all targets detected by the processing unit.

[0018] This is because in a MIMO radar, if the radome is dirty, different error signals are superimposed on each transmitting antenna that makes up the transmitting antenna section, and periodic signal errors are superimposed on the virtual array due to physical conditions such as the spacing between the transmitting antennas.

[0019] In other words, when periodic signal errors are superimposed on the virtual array, the azimuth difference of the arriving waves becomes a specific azimuth difference. Therefore, in the radar device disclosed herein, the false azimuth evaluation value calculation unit calculates, as a false azimuth evaluation value, the proportion of targets including a second arriving wave whose azimuth difference is a specific azimuth difference from the azimuth of a first arriving wave among targets with multiple numbers of arriving waves. Then, the false azimuth evaluation value is used for determining dirt.

[0020] As a result, according to the radar device disclosed herein, the MIMO radar can determine the degree of contamination of the radome with greater accuracy, and by notifying the user of the determination result, it is possible to reduce detection errors of targets caused by contamination of the radome. [Brief description of the drawings]

[0021] [Figure 1] 1 is a block diagram showing a configuration of a radar device according to an embodiment; [Diagram 2] FIG. 2 is a diagram showing the relationship between a transmitting antenna, a receiving antenna, and a target; [Diagram 3] FIG. 1 is a diagram showing the arrangement of receiving antennas in a virtual array. [Figure 4] FIG. 2 is a diagram showing the chirp repetition period. [Diagram 5] FIG. 2 is a block diagram showing a functional configuration of a processing unit. [Figure 6] 4 is an explanatory diagram illustrating a detection result of a target by a target detection unit; FIG. [Figure 7] 1 is an explanatory diagram showing a virtual array having three transmitting antennas and two receiving antennas. [Figure 8] FIG. 9 is an explanatory diagram for explaining an azimuth estimation error caused by contamination of the radome in the virtual array shown in FIG. 8. [Figure 9] 6 is a flowchart showing a dirt determination process executed by a processing unit. [Figure 10] FIG. 11 is an explanatory diagram for explaining a method for calculating a wave number from an amplitude ratio of a spectrum. [Figure 11] 11 is an explanatory diagram illustrating an increment or decrement value of a counter that is set according to a wave number evaluation value and a false orientation evaluation value. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0023] The radar device 1 of this embodiment is mounted on a vehicle and detects various targets existing around the vehicle. The radar device 1 is a MIMO radar that simultaneously transmits and receives radio waves using multiple antennas.

[0024] As shown in FIG. 1, the radar device 1 includes a transmitter 2, a transmitting antenna unit 3, a receiving antenna unit 4, a receiver 5, and a processing unit 6.

[0025] The transmitting antenna unit 3 has M transmitting antennas, where M is an integer equal to or greater than 2. The transmitting antennas are arranged in a row along a preset arrangement direction. In this embodiment, the arrangement direction is the width direction of the vehicle.

[0026] The receiving antenna unit 4 has N receiving antennas, where N is an integer equal to or greater than 2. Each receiving antenna is arranged in the same direction as the arrangement direction of the transmitting antennas.

[0027] The transmitting antenna section 3 and the receiving antenna section 4 are provided with a radome 8 that covers the entire opening surfaces, which are the radio wave emitting surfaces of the multiple transmitting antennas and the multiple receiving antennas, and protects each antenna.

[0028] Here, we will explain the signals received by each receiving antenna when M=2 and N=2. As shown in Fig. 2, it is assumed that the target to be detected is present in a direction tilted at an angle θ with respect to the front direction of the transmitting antenna unit 3 and the receiving antenna unit 4. Also, the distance between the transmitting antenna TX1 and the transmitting antenna TX2 is dT, and the distance between the receiving antenna RX1 and the receiving antenna RX2 is dR. Also, the reflection coefficient at the target is represented by D, the phase change of the signal on the path from the transmitting antenna TX1 to the target is represented by αT, and the phase change of the signal on the path from the target to the receiving antenna RX1 is represented by αR. Note that αT and αR are expressed as complex numbers.

[0029] In this case, the signal transmitted from transmitting antenna TX1 and received by receiving antenna RX1 is expressed by equation (1). The signal transmitted from transmitting antenna TX1 and received by receiving antenna RX2 is expressed by equation (2). The signal transmitted from transmitting antenna TX2 and received by receiving antenna RX1 is expressed by equation (3). The signal transmitted from transmitting antenna TX2 and received by receiving antenna RX2 is expressed by equation (4).

[0030]

number

[0031] In a MIMO radar, by using a virtual array, angular resolution equivalent to that of a single transmitting antenna and M×N receiving antennas is achieved with M+N transmitting and receiving antennas.

[0032] As shown in Fig. 1, the transmitting unit 2 includes an oscillating unit 21 and a modulating unit 22. The oscillating unit 21 generates a continuous wave common signal. The oscillating unit 21 supplies the generated common signal to the modulating unit 22 and also supplies it to the receiving unit 5 as a local signal L. As shown in Fig. 4, the oscillating unit 21 repeatedly generates a chirp signal whose frequency changes continuously for every repetition period Tp (e.g., 50 µs) during a measurement period Tm (e.g., 10 ms) at the beginning of each frame, with a measurement period Tf (e.g., 50 ms) as one frame.

[0033] The oscillator 21 is configured to be able to change the measurement period Tf, the measurement duration Tm, and the repetition period Tp as appropriate in accordance with instructions from the processor 6. The frequency width of the chirp signal that is changed during the repetition period is constant regardless of the repetition period Tp. In other words, the oscillator 21 is configured to change the rate of change Δf of the frequency of the chirp signal by changing the repetition period Tp.

[0034] The permissible range of the repetition period Tp, and therefore the permissible range of the rate of change Δf of the frequency of the chirp signal, is set so that the frequency shift caused according to the relative speed with respect to the target is small when the beat signal generated by mixing the transmitted signal and the received signal is analyzed. More specifically, the frequency shift caused according to the relative speed with respect to the target is set so that it is negligibly small compared to the frequency shift caused according to the distance from the target.

[0035] The modulation unit 22 branches the common signal generated by the oscillation unit 21 to generate M branch signals, the same number as the number of transmitting antennas belonging to the transmitting antenna unit 3. The modulation unit 22 performs phase shift keying on each of the M branch signals, changing the phase of the branch signal for each repetition period Tp. In this way, M transmission signals are generated to be supplied to each transmitting antenna. In the phase shift keying, a phase rotation amount Δφ of a different magnitude is set for each of the M branch signals, and the phase of the branch signal is rotated by that phase rotation amount Δφ for each repetition period.

[0036] Here, the number of phases used in phase shift keying is P. P is an integer larger than M. The modulation unit 22 uses P types of phase rotation amounts expressed by Δφ=p×360° / P, where p=0, 1, 2, ...., P-1. For example, in the case of P=4, Δφ=0° when p=0, and the phase difference of the transmission signal, which is the modulated signal, with respect to the branch signal (i.e., the common signal), which is the signal before modulation, is 0° in all repetition periods Tp. When p=1, Δφ=90°, and the phase difference of the transmission signal with respect to the common signal switches every repetition period Tp, changing in the order of 0°→90°→180°→270°→0° (similar below). When p=2, Δφ=180°, and the phase difference of the transmission signal with respect to the common signal switches every repetition period, changing in the order of 0°→180°→0°→180°→0° (similar below). When p=3, Δφ=270°, and the phase difference of the transmission signal with respect to the common signal switches every repetition period, changing in the order 0°→270°→180°→90°→0° (and so on).

[0037] Since P>M is set as described above, not all of the P types of phase rotation amounts Δφ are used for phase shift keying, but only a part of them.

[0038] The modulation unit 22 is configured to be able to appropriately change the setting of the number of phases P, the selection of M types of phase rotation amounts to be used for phase shift keying among the P types of phase rotation amounts Δφ, and the setting of the correspondence relationship between the selected M types of phase rotation amounts and the M transmitting antennas.

[0039] As shown in FIG. 1, the receiving unit 5 generates a beat signal, which is a difference signal between the local signal L and each of the N received signals output from each receiving antenna belonging to the receiving antenna unit 4, and samples the generated beat signal to supply it to the processing unit 6.

[0040] The processing unit 6 is an electronic control device mainly composed of a known microcomputer including a CPU 61 and a memory 62. The memory 62 is, for example, a ROM and a RAM. Various functions of the microcomputer are realized by the CPU 61 executing a program stored in a non-transient real recording medium. In this example, the memory 62 corresponds to the non-transient real recording medium storing the program.

[0041] Furthermore, by executing this program, a method corresponding to the program is executed. Note that some or all of the functions executed by the CPU 61 may be configured in hardware using one or more ICs, etc. Also, the number of microcomputers configuring the processing unit 6 may be one or more.

[0042] Next, as shown in FIG. 5, the processing unit 6 has, as its functional configuration, a target detection unit 72, a target information output unit 74, a wave number calculation unit 82, a wave number evaluation value calculation unit 84, a false orientation evaluation value calculation unit 86, and a dirt determination unit 88.

[0043] The target detection unit 72 sets a repetition period Tp, which is a parameter related to the common signal generated by the oscillator 21, and the number of phases P used for phase shift keying in the modulator 22. In addition, from among P types of phase rotation amounts determined by the number of phases P, it selects M types of phase rotation amounts to be used for phase shift keying in the modulator 22, and sets a correspondence between the selected M types of phase rotation amounts and each transmitting antenna.

[0044] Then, the transmitter 2 is operated according to the setting result thus set, and radar measurement is performed. Specifically, the transmitter 2 is made to repeatedly transmit a chirp signal at each repetition period Tp during the measurement period Tm, and a sampling result of a beat signal generated from the received signal is obtained. Hereinafter, the number of chirp signals repeatedly transmitted during the measurement period Tm is assumed to be K.

[0045] Next, the sampling results of the beat signals obtained from the N receiving antennas are frequency-analyzed for each receiving antenna and for each chirp signal, thereby calculating K distance spectra for each of the N receiving antennas. In each distance spectrum, a peak appears at a frequency corresponding to the time required for the reflected wave transmitted from the transmitting antenna to travel to and from the target (i.e., the distance to the target).

[0046] The target detection unit 72 also calculates a speed spectrum for each receiving antenna using the N×K distance spectra. Specifically, signals of the same frequency are extracted from the K distance spectra related to the receiving antenna of interest, and frequency analysis processing is performed on the extracted signals in the time axis direction.

[0047] As a result, a two-dimensional spectrum (hereinafter, "receiving spectrum") representing the distance and relative speed of the target that reflected the radar wave is generated for each receiving antenna. Then, the target detection unit 72 integrates the receiving spectra generated for each receiving antenna to generate a detection result in which a power spectrum peak occurs for each target in a coordinate system of the distance R to the target and the relative speed V between the target, as shown in FIG.

[0048] The target detection unit 72 also extracts peaks corresponding to the same target having the same distance R and relative speed V from each of the reception spectra calculated for each receiving antenna. Then, the target detection unit 72 performs a known direction detection process such as the MUSIC method, the beamformer method, or the Capon method on the extracted peaks to calculate the direction θ of each target. Note that MUSIC is an abbreviation for Multiple signal classification.

[0049] The target detection unit 72 outputs the direction θ, distance R, and relative speed V of each target calculated as described above to the target information output unit 74 as target information of each target, and outputs it to an external device such as a vehicle driving support device. Note that target detection in such a MIMO radar is described in, for example, JP 2019-128235 A and is a publicly known technology, so a detailed description will be omitted here.

[0050] Next, the wave number calculation unit 82 calculates the wave number of the incoming wave from each target obtained when the target detection unit 72 determines the azimuth θ for each target by azimuth detection processing such as the MUSIC method, the beamformer method, or the Capon method.

[0051] In addition, the wave number evaluation value calculation unit 84 calculates the proportion of targets with multiple wave numbers calculated by the wave number calculation unit 82 among all targets detected by the target detection unit 72 as a wave number evaluation value.

[0052] In addition, the false orientation evaluation value calculation unit 86 calculates, as a false orientation evaluation value, the proportion of targets including a second arriving wave whose orientation difference is a specific orientation difference from the orientation of a first arriving wave whose power of the arriving wave is maximum, among targets having multiple wave numbers calculated by the wave number calculation unit 82.

[0053] Then, the dirt determination unit 88 determines whether the radome 8 is dirty or not based on the wave number evaluation value calculated by the wave number evaluation value calculation unit 84 and the false orientation evaluation value calculated by the false orientation evaluation value calculation unit 86, and outputs the determination result to an external device such as a vehicle driving support device. Note that the dirt on the radome 8 determined by the dirt determination unit 88 also includes adhesion of water to the radome 8, freezing on the radome 8, and the like.

[0054] Next, the false orientation evaluation value calculation unit 86 will be described.

[0055] First, the specific azimuth difference is a constant azimuth difference (for example, 14° to 16°) that occurs due to periodic signal errors being superimposed on the virtual array.

[0056] For example, when the number of transmitting antennas M=3 and the number of receiving antennas N=2, the virtual array is composed of six virtual receiving antennas T1R1 to T3R2 shown in FIG. 7 by combining transmitting antennas T1, T2, T3 and receiving antennas R1, R2.

[0057] When the radome 8 becomes dirty, different error signals are superimposed on the transmission waves from the transmitting antennas T1 to T3, and the received signals of the six virtual receiving antennas T1R1 to T3R2 each contain the error signals of the corresponding transmitting antennas T1 to T3.

[0058] Here, in the virtual receiving antennas T1R1 to T3R2, as shown in Fig. 7, radio waves incident from a specific direction become received signals with the same amplitude (r) and a phase (θ) proportional to the antenna spacing (x), so the received signals can be described as follows. Note that this received signal is an ideal signal shown in Fig. 8.

[0059]

number

[0060]

number

[0061] In contrast, when the radome 8 is contaminated and an error signal is superimposed on the transmission waves from the transmitting antennas T1 to T3, the error signal differs for each of the transmitting antennas T1 to T3, and S(Φ)=X, Y, Z.

[0062] Therefore, error signals X, Y, Z, X, Y, Z are superimposed on the received signals from the virtual receiving antennas T1R1, T2R1, T3R1, T1R2, T2R2, T3R2, respectively, and a periodic signal error is carried on the virtual array. This periodic signal error causes the direction of the arriving wave from the target to vary, and the direction difference becomes an approximately constant angle, that is, a specific direction difference, depending on physical conditions such as the spacing between the transmitting antennas T1 to T3.

[0063] Therefore, in the false orientation evaluation value calculation unit 86, it is determined that, among targets having multiple numbers of incoming waves, the orientation of a target including a second incoming wave whose orientation difference is a specific orientation difference from the orientation of a first incoming wave whose power of the incoming wave is maximum is erroneously detected due to dirt on the radome 8.

[0064] Then, the false orientation evaluation value calculation unit 86 calculates, as a false orientation evaluation value, the ratio of targets whose orientations are erroneously detected due to contamination of the radome 8 among targets with multiple wave numbers of arriving waves. When this ratio is large, the probability that the radome 8 is contaminated increases, so the false orientation evaluation value becomes a parameter suitable for determining the contamination of the radome 8.

[0065] As shown in FIG. 8, if the radome 8 is contaminated only on the receiving antenna side, not on the transmitting antenna side, a different signal error is simply added to each of the receiving antennas R1 and R2, so the degree of contamination of the radome 8 cannot be determined.

[0066] Next, the dirt determination process executed by the CPU 61 to realize the functions of the wave number calculation unit 82, the wave number evaluation value calculation unit 84, the false orientation evaluation value calculation unit 86, and the dirt determination unit 88 will be described with reference to the flowchart of FIG.

[0067] The dirt determination process is a process that is executed periodically by the CPU 61 each time the target detection process is executed as the target detection unit 72, in other words, in synchronization with the target detection process, and is carried out by the CPU 61 executing a program stored in the memory 62.

[0068] As shown in FIG. 9, in the dirt determination process, first in S110, the number of targets detected by the target detection unit 72, that is, the number of power spectra whose peak levels reach the target determination level in the coordinate system of distance R and relative velocity V shown in FIG. 6 (hereinafter, the number of peaks) is calculated.

[0069] Next, in S120, the process as wave number calculation unit 82 is executed to calculate the wave number of the arriving waves for each peak (that is, each target) whose number of peaks has been calculated in S120.

[0070] For example, when the target detection unit 72 detects the direction using the beamformer method or the Capon method, it is possible to obtain a direction spectrum whose level changes according to the direction, as shown in FIG.

[0071] Therefore, in S120, in this azimuth spectrum, spectra whose peaks are within a predetermined judgment power range relative to the maximum azimuth power at which the spectrum peak is maximum are extracted, and the number of these spectra is calculated as the number of arriving waves.

[0072] For example, in FIG. 10, the second azimuth power is within the judgment power range and the third azimuth power is outside the judgment power range, so the number of spectra of the first azimuth power and the second azimuth power=2 is calculated as the number of waves of the arriving wave.

[0073] Next, in S130, the number of peaks whose wave numbers are calculated in S120 and whose wave numbers are 1 is calculated. In addition, in S140, the number of peaks whose wave numbers are 2 or more is calculated, among all peaks whose wave numbers are calculated in S120.

[0074] Furthermore, in S150, the number of peaks containing a second arriving wave whose azimuth difference from the first arriving wave, which has the maximum power of the arriving wave, is the above-mentioned specific azimuth difference is calculated as the number of false azimuth peaks, among the peaks with a wave number of two or more.

[0075] Then, in S160, the proportion of peaks with a wave number of 2 or more among all peaks is calculated as a wave number evaluation value from all peak numbers CPA, the number of peaks CP1 with a wave number of 1, and the number of peaks CP2 with a wave number of 2 or more calculated in S110, S130, and S140. Note that this wave number evaluation value is calculated, for example, as "wave number evaluation value = (CP2 - CP1) / CPA".

[0076] Next, in S170, a false orientation evaluation value is calculated using the number of peaks CP2 with two or more waves calculated in S140 and the number of false orientation peaks CPD calculated in S150. The false orientation evaluation value is calculated, for example, as "false orientation evaluation value=CPD / CP2".

[0077] 9, the processes of S130, S140, and S160 function as the wave number evaluation value calculation unit 84, and the processes of S140, S150, and S170 function as the false orientation evaluation value calculation unit 86.

[0078] Next, in S180, thresholds A and B used to determine contamination of the radome 8 are set based on the wavenumber evaluation value and the false orientation evaluation value. In S180, normal values, for example, a value of 0.5, are set as the thresholds A and B in normal times.

[0079] In addition, in an environment where the radome 8 is likely to freeze, the threshold A for the wavenumber evaluation value is set to, for example, a value of 0, and the threshold B for the false orientation evaluation value is set to, for example, a value of 0.2, so that the contamination of the radome 8 can be easily determined.

[0080] Examples of environments in which the radome 8 is likely to freeze include when the temperature outside the vehicle, i.e., the outside air temperature, is a low temperature equal to or lower than a predetermined temperature (e.g., 5°C), or when a heater for heating a member around the radar device 1, such as an emblem, is driven. Therefore, in S180, when the temperature is low or when the heater is driven, the thresholds A and B are set to values ​​smaller than the normal values.

[0081] Next, in S190, it is determined whether the wave number evaluation value is greater than threshold A and the false orientation evaluation value is greater than threshold B. If the wave number evaluation value>threshold A and the false orientation evaluation value>threshold B, the process proceeds to S200, where the dirt counter is incremented (+1), and if not, the process proceeds to S210, where the dirt counter is decremented (-1).

[0082] When the value of the dirt counter is updated in this manner, in S220, it is determined whether or not the value of the dirt counter is greater than a preset threshold value C. If the value of the dirt counter is greater than the threshold value C, it is determined that the radome 8 is dirty, and the process proceeds to S230.

[0083] Then, in S230, the dirt flag is turned on to store that the radome 8 is dirty, and the dirt determination process is terminated. If it is determined in S220 that the dirt counter value is equal to or less than the threshold value C, the process proceeds to S240, where the dirt flag is turned off, and the dirt determination process is terminated.

[0084] The processes of S180 to S240 function as the dirt determination unit 88. The process of S180 corresponds to the threshold setting unit of the present disclosure, the processes of S190 to S210 correspond to the dirt determination value updating unit of the present disclosure, and the dirt counter corresponds to the dirt determination value of the present disclosure.

[0085] As described above, in the radar device 1 of this embodiment, the wave number evaluation value and the false direction evaluation value are used to judge the dirt on the radome 8. Among these, the wave number evaluation value is the ratio of targets detected by the target detection unit 72 that have two or more incoming waves from the target.

[0086] In contrast, the false azimuth evaluation value is the percentage of targets for which the azimuth difference between the two waves is a specific azimuth difference, among targets for which there are two or more incoming waves, that is, targets that may have been erroneously detected as having two or more incoming waves due to dirt on the radome 8.

[0087] Therefore, according to the radar device 1 of this embodiment, it is possible to more accurately determine the contamination of the radome 8 compared to a device that determines the contamination of the radome 8 based only on the wave number evaluation value. Furthermore, since the determination result of the contamination of the radome 8 is output to an external device such as a driving support device of the vehicle, it is possible to notify the user of the contamination of the radome 8 via the external device and to eliminate the contamination of the radome 8. Therefore, it is possible to reduce detection errors of targets caused by the contamination of the radome 8.

[0088] Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment and can be implemented in various modified forms.

[0089] For example, in the above embodiment, the dirt counter used to determine the dirt on the radome 8 is described as being incremented when the wave number evaluation value is greater than threshold A and the false orientation evaluation value is greater than threshold B, and is decremented otherwise.

[0090] In contrast, the threshold A and threshold B for the wave number evaluation value and false orientation evaluation value may be set to two types of thresholds, high and low, H and L, respectively. In this case, as illustrated in FIG. 11, when one of the wave number evaluation value and false orientation evaluation value is equal to or greater than the threshold H and the other of the wave number evaluation value and false orientation evaluation value is equal to or greater than the threshold L and less than the threshold H, the update value of the dirt counter can be set to 0 and the update can be stopped. Therefore, compared to the above embodiment, the update of the dirt counter can be suppressed. In this case, when both the wave number evaluation value and the false orientation evaluation value are less than the threshold L, the dirt counter can also be reset.

[0091] Next, in the above embodiment, the radar device 1 has been described as an example of a so-called DDM type MIMO radar that generates a transmission signal to be supplied to each transmitting antenna by performing phase shift keying on each of M branch signals, the number of which is the same as the number of transmitting antennas.

[0092] However, the present disclosure can be applied to any MIMO radar in the same manner as above to obtain the same effect, and the modulation method of the transmission signal is not limited to phase shift keying. In other words, the radar device of the present disclosure may be, for example, an FDMA MIMO radar that divides the transmission signal by frequency, or a TDMA MIMO radar that divides the transmission signal by time.

[0093] The processing unit 6 and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the processing unit 6 and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the processing unit 6 and the method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer. The method for realizing the functions of each unit included in the processing unit 6 does not necessarily need to include software, and all of the functions may be realized using one or more hardware.

[0094] In the above embodiments, multiple functions of one component may be realized by multiple components, or one function of one component may be realized by multiple components. Also, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, part of the configuration of the above embodiments may be omitted. Also, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0095] In addition to the above-described radar device 1, the present disclosure can also be realized in various forms, such as a system including the radar device 1 as a component, a program for causing a computer to function as the radar device 1, a non-transient physical recording medium such as a semiconductor memory on which this program is recorded, and a method for determining dirt.

Claims

1. A transmitting antenna unit (3) having a plurality of transmitting antennas; An oscillator (21) configured to generate a continuous wave common signal; a modulation unit (22) configured to perform a predetermined modulation on each of a plurality of branch signals obtained by branching the common signal into the same number as the plurality of transmitting antennas, thereby generating a plurality of transmission signals to be input to the plurality of transmitting antennas; A receiving antenna section (4) having a plurality of receiving antennas; a processing unit (6) configured to detect each of the targets that have reflected the transmission wave from the transmitting antenna unit, based on a plurality of signal components corresponding to the plurality of transmission signals that are extracted from each of a plurality of reception signals received by the receiving antenna unit; A radome (8) that covers the openings of the transmitting antennas and the receiving antennas and protects them from the outside; a virtual array having a plurality of virtual receiving antennas is formed by the plurality of transmitting antennas and the plurality of receiving antennas; The processing unit includes: a wave number calculation unit (82) that calculates the number of waves of an incoming wave reflected from each of the detected targets; a wave number evaluation value calculation unit (84) configured to calculate, as a wave number evaluation value, a ratio of targets having a plurality of wave numbers calculated by the wave number calculation unit to all detected targets; a false heading evaluation value calculation unit (86) configured to calculate, as a false heading evaluation value, a ratio of targets having a specific heading difference between the two incoming waves caused by a periodic signal error being superimposed on the virtual array among the targets having two or more incoming waves calculated by the wave number calculation unit; a contamination determination unit (88) configured to determine contamination of the radome based on the wavenumber evaluation value and the false orientation evaluation value; A radar device comprising:

2. The radar device according to claim 1 , The dirt determination unit is a contamination judgment value update unit that updates a contamination judgment value by adding the wave number evaluation value and the false orientation evaluation value when they are equal to or greater than a preset threshold value, and subtracting them otherwise, and is configured to determine that the radome is contaminated when the contamination judgment value becomes equal to or greater than a predetermined value, The radar device further includes a threshold setting unit that switches at least one of the thresholds for the wave number evaluation value and the false orientation evaluation value so that contamination of the radome can be easily determined when the air temperature is below a predetermined temperature or when a heater that heats components around the radar device is driven.

Images