Signal processing device, signal processing method, and radar device

Abstract

A signal processing device (4) is configured so as to be provided with: a map generation unit (13) that acquires a reception signal of a reflected wave from a reception unit (1) that receives the reflected wave reflected by an object present around a moving body, and generates a distance Doppler map indicating the signal strength level of the reception signal; and a height standard deviation calculation unit (15) that calculates the standard deviation of the height at which the object is located on the basis of the distance Doppler map generated by the map generation unit (13). Furthermore, the signal processing device (4) is provided with a collision determination unit (17) that determines, on the basis of the standard deviation calculated by the height standard deviation calculation unit (15), whether or not the object is present at a height at which the moving body may collide with the object.

Description

Technical Field

[0001] The present disclosure relates to a signal processing device, a signal processing method, and a radar device. Background Art

[0002] There is a radar device that determines whether an object exists at a height at which a moving body and an object may collide (hereinafter referred to as a "conventional radar device"). There is a driving support system having the following function: obtaining a determination result of the conventional radar device, and braking the moving body if the determination result indicates that an object exists at a height at which a collision may occur. In a multipath environment in which the reflected wave reflected by the target object includes multipath waves from the target object in addition to a direct wave from the target object, the estimation accuracy of the height of the object by the conventional radar device deteriorates, and as a result, the conventional radar device sometimes makes an erroneous determination.

[0003] For example, Patent Document 1 discloses a radar device that estimates the height of a target object.

[0004] The radar device disclosed in Patent Document 1 is provided with a plurality of sensor units, a variance calculation unit, and a data selection unit in order to suppress the degradation of the estimation accuracy of the height in a multipath environment. Each sensor unit is provided with: a transceiver unit that receives a reflected wave reflected by a target object; and a position measurement unit that measures the height of the target object based on the received signal of the reflected wave. The variance calculation unit calculates the variance of the height measured by the sensor units included in each combination including all or part of the plurality of sensor units. The data selection unit selects the combination with the smallest variance calculated by the variance calculation unit from the plurality of combinations, and calculates the average value of the heights measured by the sensor units included in the selected combination as the height of the target object.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2012-189474 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] The radar device disclosed in Patent Document 1 has a problem in that it needs to include a plurality of sensor units.

[0010] The present disclosure is completed to solve the above problems, and its purpose is to obtain a signal processing device that can determine whether there is an object at a height where a moving body and the object may collide based on a reception signal of a reflected wave received by only one receiving unit in a multipath environment.

[0011] Means used to solve problems

[0012] The signal processing device of the present disclosure includes: a map generation unit that obtains a reception signal of a reflected wave from a reception unit that receives a reflected wave reflected by an object existing around a moving body, and generates a range Doppler map showing a signal strength level of the received signal; and a height standard deviation calculation unit that calculates a standard deviation of a height at which the object exists based on the range Doppler map generated by the map generation unit. In addition, the signal processing device includes a collision determination unit that determines whether the object exists at a height at which the moving body and the object may collide based on the standard deviation calculated by the height standard deviation calculation unit.

[0013] Effects of the Invention

[0014] According to the present disclosure, in a multipath environment, it is possible to determine whether an object exists at a height where a moving object may collide with the object based on a reception signal of a reflected wave received by only one receiving unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a diagram showing the configuration of a radar device according to Embodiment 1.

[0016] Figure 2 1 is a hardware configuration diagram showing the hardware of the signal processing device 4 according to the first embodiment.

[0017] Figure 3 This is a hardware configuration diagram of a computer when the signal processing device 4 is implemented by software, firmware, or the like.

[0018] Figure 4 : is a flowchart showing a signal processing method as a processing procedure of the signal processing device 4.

[0019] Figure 5 1 is an explanatory diagram showing an example of the RD map generated by the map generating unit 13 .

[0020] Figure 6 It is an explanatory diagram showing the positional relationship between a vehicle and an overhead object, and a reflected wave reflected by the overhead object.

[0021] Figure 7 It is an explanatory diagram showing the relationship between the ground distance when the object is an object above, in front of, or below, and the power of the received signal s when the direct wave and the multipath wave overlap.

[0022] Figure 8 The first threshold value Th UP，r This is an illustration of an example of settings.

[0023] Fig. 9 The second threshold value Th DW，r This is an illustration of an example of settings.

[0024] Fig.10 This is an explanatory diagram showing an example of the angle measurement values ​​of each elevation angle of an object above, an object in front, and an object below.

[0025] Fig.11 It is an explanatory diagram showing an example of the standard deviation of each height of an object, which is an upper object, a front object, and a lower object.

[0026] Fig.12 This is an explanatory diagram showing an example of the standard deviation of the received signal power of each reflected wave of an object, which is an upper object, a front object, and a lower object.

[0027] Fig.13 2 is a flowchart showing the determination processing of the determination processing unit 17 c.

[0028] Fig.14 This is a diagram showing the structure of a radar device according to the second embodiment.

[0029] Fig.15 This is a hardware configuration diagram showing the hardware of the signal processing device 4 according to the second embodiment.

[0030] Fig.16 This is an explanatory diagram showing a plurality of objects having different azimuth angles relative to a vehicle. DETAILED DESCRIPTION

[0031] Hereinafter, in order to explain the present disclosure in more detail, the mode for implementing the present disclosure will be described with reference to the drawings.

[0032] Implementation method 1.

[0033] Figure 1 This is a diagram showing the configuration of a radar device according to Embodiment 1.

[0034] Figure 2 1 is a hardware configuration diagram showing the hardware of the signal processing device 4 according to the first embodiment.

[0035] Figure 1 The radar device shown includes a receiving unit 1 , a signal processing device 4 , and a determination result output unit 5 .

[0036] The receiving unit 1 includes an antenna 2 and an analog-to-digital converter (hereinafter referred to as “ADC unit”) 3 .

[0037] The receiving unit 1 receives reflected waves reflected by objects around the moving body. The receiving unit 1 outputs received signals of reflected waves at multiple times to the signal processing device 4. The moving body includes, for example, a vehicle, a train, a ship, or a person. In addition to four-wheeled cars, the vehicle also includes a motorcycle, a bicycle, or an electric stand-up two-wheeled vehicle.

[0038] exist Figure 1 In the radar device shown, for convenience, the moving object is described as a vehicle, but the moving object may be, for example, a train or a ship.

[0039] The antenna 2 receives the reflected wave reflected by the object, and outputs a reception signal of the reflected wave to the ADC unit 3 .

[0040] The ADC unit 3 acquires reception signals of reflected waves from the antenna 2 at a plurality of times.

[0041] The ADC unit 3 converts the reception signal at each time from an analog signal to a digital signal at a sampling frequency set in advance.

[0042] The ADC unit 3 outputs a digital signal as a reception signal of a reflected wave to the signal processing device 4 .

[0043] The signal processing device 4 includes a storage unit 11 and a signal processing unit 12 .

[0044] The signal processing device 4 determines whether or not an object exists at a height at which a vehicle as a moving body may collide with the object based on the digital signal output from the ADC unit 3 .

[0045] The signal processing device 4 outputs the determination result to the determination result output unit 5 .

[0046] As an object that exists at a height that may collide with the vehicle, for example, there are other vehicles, pedestrians, or guardrails. As an object that does not exist at a height that may collide with the vehicle, for example, there are manholes, grilles, signs, or pedestrian bridges.

[0047] The storage unit 11 is composed of, for example, Figure 2 The storage circuit 21 shown is implemented.

[0048] The storage unit 11 stores not only the digital signals output from the ADC unit 3 but also the determination results of the signal processing unit 12 and the like.

[0049] The signal processing unit 12 includes a map generating unit 13 , a distance interval calculating unit 14 , a height standard deviation calculating unit 15 , an azimuth angle detecting unit 16 , and a collision determining unit 17 .

[0050] The graph generating unit 13 is, for example, Figure 2 The graph generation circuit 23 shown is implemented.

[0051] The map generating unit 13 acquires digital signals at a plurality of times from the receiving unit 1 as reception signals of reflected waves at a plurality of times.

[0052] The map generator 13 generates a range Doppler map (hereinafter referred to as an RD map) showing the signal strength level of the received signal based on the digital signal. The RD map is a two-dimensional map showing the signal strength level of the received signal corresponding to the relative distance and relative speed between the vehicle and the object.

[0053] The map generating unit 13 outputs the RD map to the distance interval calculating unit 14 , the height standard deviation calculating unit 15 , and the azimuth angle detecting unit 16 .

[0054] The distance interval calculation unit 14 is, for example, Figure 2 The distance interval calculation circuit 24 shown is implemented.

[0055] The distance interval calculation unit 14 includes a peak detection unit 14 a , an elevation angle calculation unit 14 b , a propagation distance calculation unit 14 c , and a distance interval calculation processing unit 14 d .

[0056] The distance interval calculation unit 14 calculates the distance interval at which the direct wave from the object included in the reflected wave and the multipath wave from the object included in the reflected wave interfere with each other, based on the RD graph generated by the graph generation unit 13. The distance interval at which the direct wave and the multipath wave interfere with each other includes a distance interval at which the direct wave and the multipath wave reinforce each other or a distance interval at which the direct wave and the multipath wave weaken each other.

[0057] The distance interval calculation unit 14 outputs distance interval information indicating the calculated distance interval to the collision determination unit 17 .

[0058] The peak detection unit 14 a detects a peak of the signal intensity level based on the RD map generated by the map generation unit 13 .

[0059] Specifically, the peak detection unit 14a detects a threshold value Th related to a constant false alarm rate (CFAR) among a plurality of signal strength levels shown in the RD map generated by the map generation unit 13. CFAR The signal strength level with the largest value is regarded as the peak of the signal strength level. CFAR The relative distance associated with a large signal strength level is the relative distance between the vehicle and the object, which is greater than the threshold Th CFAR The relative speed to which a large signal strength level is associated is the relative speed between the vehicle and the object.

[0060] The peak detection unit 14 a outputs detection information indicating a relative distance associated with the detected peak and a relative speed associated with the detected peak to the elevation angle calculation unit 14 b and the propagation distance calculation unit 14 c .

[0061] The elevation angle calculation unit 14 b calculates a plurality of elevation angles of the object relative to the vehicle when the direct wave and the multipath wave interfere with each other, based on the detection information output from the peak detection unit 14 a .

[0062] Specifically, the elevation angle calculation unit 14 b performs arrival direction estimation processing using the correlation matrix and eigenvectors of the received signal based on the detection information output from the peak detection unit 14 a , thereby calculating the eigenvalues ​​of the correlation matrix.

[0063] The elevation angle calculation unit 14b estimates the number of arrival waves based on the number of eigenvalues ​​with greater power than thermal noise, and estimates the elevation angle of the object based on the number of arrival waves. As the arrival direction estimation process, for example, the MUSIC (Multiple Signal Classification) method or the ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) method can be used. The elevation angle of the object can be estimated using the MUSIC method or the ESPRIT method.

[0064] The elevation angle calculation unit 14b outputs elevation angle information indicating the calculated plurality of elevation angles to each of the propagation distance calculation unit 14c and the distance interval calculation processing unit 14d.

[0065] Furthermore, the elevation angle calculation unit 14 b may store the elevation angle information in the storage unit 11 .

[0066] The propagation distance calculation unit 14 c calculates a plurality of propagation distances of the direct wave when the direct wave and the multipath wave interfere with each other, based on the detection information output from the peak detection unit 14 a and the elevation angle information output from the elevation angle calculation unit 14 b .

[0067] The propagation distance calculation unit 14c outputs propagation distance information indicating the calculated plurality of propagation distances to the distance interval calculation processing unit 14d.

[0068] The distance interval calculation processing unit 14d calculates the difference between the mth (m is an integer greater than or equal to 1)th propagation distance and the (m+1)th propagation distance among the plurality of propagation distances indicated by the propagation distance information output from the propagation distance calculation unit 14c as the distance interval at which the direct wave from the object and the multipath wave from the object interfere with each other. The mth propagation distance is a propagation distance associated with the mth longest relative distance among the plurality of relative distances between the vehicle and the object when the direct wave and the multipath wave interfere with each other. The (m+1)th propagation distance is a propagation distance associated with the (m+1)th longest relative distance among the plurality of relative distances between the vehicle and the object.

[0069] Instead of calculating the difference between the m-th propagation distance and the (m+1)-th propagation distance as the distance interval that interferes with each other, the distance interval calculation processing unit 14d may calculate the distance interval that interferes with each other based on the m-th elevation angle and the (m+1)-th elevation angle among the plurality of elevation angles indicated by the elevation angle information output from the elevation angle calculation unit 14b. The m-th elevation angle is an elevation angle associated with the m-th longest relative distance among the plurality of relative distances between the vehicle and the object when the direct wave and the multipath wave interfere with each other. The (m+1)-th elevation angle is an elevation angle associated with the (m+1)-th longest relative distance among the plurality of relative distances between the vehicle and the object.

[0070] The distance interval calculation processing unit 14 d outputs distance interval information indicating the distance interval to the collision determination unit 17 .

[0071] The height standard deviation calculation unit 15 is, for example, Figure 2 The height standard deviation calculation circuit 25 shown is implemented.

[0072] The height standard deviation calculation unit 15 includes a peak detection unit 15 a , a height calculation unit 15 b , and a standard deviation calculation processing unit 15 c .

[0073] The height standard deviation calculation unit 15 calculates the standard deviation of the height where the object is located based on the RD map generated by the map generation unit 13 .

[0074] The height standard deviation calculation unit 15 outputs the calculation result of the standard deviation to the collision determination unit 17 .

[0075] The peak detection unit 15 a detects a peak of the signal intensity level based on the RD map generated by the map generation unit 13 , similarly to the peak detection unit 14 a .

[0076] The peak detection section 15 a outputs detection information each showing a relative distance with respect to the detected peak and a relative speed with respect to the detected peak to the height calculation section 15 b .

[0077] The height calculation unit 15 b calculates the heights of the object at each of a plurality of times based on the detection information output from the peak detection unit 15 a .

[0078] The altitude calculation unit 15b outputs altitude information indicating altitudes at a plurality of time points to the standard deviation calculation processing unit 15c.

[0079] The standard deviation calculation processing unit 15c calculates the standard deviation of the altitude based on the altitudes at a plurality of times indicated by the altitude information output from the altitude calculation unit 15b.

[0080] The standard deviation calculation processing unit 15 c outputs the calculation result of the standard deviation to the collision determination unit 17 .

[0081] The azimuth angle detection unit 16 is composed of, for example, Figure 2 The azimuth angle detection circuit 26 is shown implemented.

[0082] The azimuth angle detection unit 16 includes a peak detection unit 16 a and an azimuth angle detection processing unit 16 b .

[0083] The azimuth angle detection unit 16 detects the azimuth angle of the object relative to the vehicle based on the RD map generated by the map generation unit 13 .

[0084] The azimuth angle detection unit 16 outputs azimuth angle detection information indicating the azimuth angle of the object to the collision determination unit 17 .

[0085] The peak detection unit 16 a detects a peak of the signal intensity level based on the RD map generated by the map generation unit 13 , similarly to the peak detection unit 14 a .

[0086] The peak detection section 16 a outputs detection information each showing a relative distance with respect to the detected peak and a relative speed with respect to the detected peak to the azimuth detection processing section 16 b .

[0087] exist Figure 1 In the signal processing device 4 shown in the figure, the distance interval calculation unit 14 includes a peak detection unit 14a, the height standard deviation calculation unit 15 includes a peak detection unit 15a, and the azimuth angle detection unit 16 includes a peak detection unit 16a. However, this is just an example, and for example, the signal processing device 4 may include one peak detection unit, and the distance interval calculation unit 14, the height standard deviation calculation unit 15, and the azimuth angle detection unit 16 may each use detection information output from one peak detection unit.

[0088] The azimuth detection processing unit 16 b calculates a plurality of elevation angles of the object relative to the vehicle when the direct wave and the multipath wave interfere with each other, based on the detection information output from the peak detection unit 16 a .

[0089] Specifically, the azimuth detection processing unit 16 b performs arrival direction estimation processing using the correlation matrix and eigenvectors of the received signal based on the detection information output from the peak detection unit 16 a , thereby calculating the eigenvalues ​​of the correlation matrix.

[0090] The azimuth detection processing unit 16b estimates the number of arrival waves based on the number of eigenvalues ​​greater than the power of thermal noise, and estimates the azimuth of the object based on the number of arrival waves. As the arrival direction estimation process, for example, the MUSIC method or the ESPRIT method can be used. By using the MUSIC method or the ESPRIT method, the azimuth of the object can be estimated.

[0091] The azimuth detection processing unit 16 b outputs azimuth information indicating the azimuth of the object to the collision determination unit 17 .

[0092] The collision determination unit 17 is composed of, for example, Figure 2 The collision determination circuit 27 shown is implemented.

[0093] The collision determination unit 17 includes a first score calculation unit 17 a , a second score calculation unit 17 b , and a determination processing unit 17 c .

[0094] If the azimuth indicated by the azimuth information output from the azimuth detection unit 16 is consistent with the vehicle's traveling direction, the collision determination unit 17 determines whether the object is at a height at which the vehicle may collide based on the distance interval calculated by the distance interval calculation unit 14 and the standard deviation calculated by the height standard deviation calculation unit 15.

[0095] The azimuth angle coincides with the vehicle's traveling direction, meaning that when the vehicle is traveling, the vehicle and the object overlap on the horizontal plane. On the other hand, the azimuth angle does not coincide with the vehicle's traveling direction, meaning that even when the vehicle is traveling, the vehicle and the object do not overlap on the horizontal plane.

[0096] The collision determination unit 17 outputs the determination result to the determination result output unit 5 .

[0097] Furthermore, the collision determination unit 17 may store the determination result in the storage unit 11 .

[0098] The first score calculation unit 17 a determines whether the azimuth indicated by the azimuth information output from the azimuth detection unit 16 coincides with the traveling direction of the vehicle.

[0099] If the azimuth angle coincides with the traveling direction of the vehicle, the first score calculation unit 17 a calculates a first score based on the distance interval calculated by the distance interval calculation unit 14 .

[0100] The first score calculation unit 17a outputs the first score to the determination processing unit 17c.

[0101] The second score calculation unit 17 b determines whether the azimuth indicated by the azimuth information output from the azimuth detection unit 16 coincides with the traveling direction of the vehicle.

[0102] If the azimuth angle coincides with the traveling direction of the vehicle, the second score calculation unit 17 b calculates the second score based on the standard deviation calculated by the height standard deviation calculation unit 15 .

[0103] The second score calculation unit 17b outputs the second score to the determination processing unit 17c.

[0104] The determination processing unit 17 c calculates a comprehensive index value which is the sum of the first score calculated by the first score calculation unit 17 a and the second score calculated by the second score calculation unit 17 b .

[0105] The determination processing unit 17 c determines whether or not the object is at a height at which the vehicle and the object may collide, based on the comparison result between the comprehensive index value and the threshold value.

[0106] That is, if the comprehensive index value is larger than the first comprehensive threshold value Th1, the determination processing unit 17c determines that the object exists above the vehicle and the object does not exist at a height at which the vehicle and the object may collide.

[0107] If the comprehensive index value is smaller than the second comprehensive threshold value Th2, the determination processing unit 17c determines that the object exists below the vehicle and the object does not exist at a height at which the vehicle and the object may collide.

[0108] If the comprehensive index value is equal to or less than the first comprehensive threshold value Th1 and the comprehensive index value is equal to or greater than the second comprehensive threshold value Th2, the determination processing unit 17c determines that the object exists at a height at which the vehicle and the object may collide.

[0109] The determination processing unit 17 c outputs the determination result to the determination result output unit 5 .

[0110] Furthermore, the determination processing unit 17 c may store the determination result in the storage unit 11 .

[0111] The first comprehensive threshold value Th1 and the second comprehensive threshold value Th2 may be stored in an internal memory of the determination processing unit 17 c , or may be provided from outside the signal processing device 4 .

[0112] The determination result output unit 5 obtains the determination result output from the collision determination unit 17 of the signal processing device 4, and outputs the determination result to, for example, a vehicle speed control device (not shown). The vehicle speed control device is, for example, a device that controls the running speed of the vehicle, and if the determination result of the signal processing device 4 indicates that an object exists at a height at which the vehicle and the object may collide, the running speed of the vehicle is controlled so that the vehicle does not collide with the object.

[0113] exist Figure 1 In the above, it is assumed that the storage unit 11, the map generation unit 13, the distance interval calculation unit 14, the height standard deviation calculation unit 15, the azimuth angle detection unit 16 and the collision determination unit 17 as the structural elements of the signal processing device 4 are respectively Figure 2 Specifically, it is assumed that the signal processing device 4 is implemented by the storage circuit 21, the map generation circuit 23, the distance interval calculation circuit 24, the height standard deviation calculation circuit 25, the azimuth angle detection circuit 26 and the collision determination circuit 27.

[0114] Here, the storage circuit 21 corresponds to, for example, RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), EEPROM (Electrically EPROM), or other non-volatile or volatile semiconductor memories, magnetic disks, floppy disks, optical disks, high-density disks, mini disks, or DVDs (Digital Versatile Discs).

[0115] In addition, the graph generation circuit 23, the distance interval calculation circuit 24, the height standard deviation calculation circuit 25, the azimuth angle detection circuit 26 and the collision judgment circuit 27 respectively correspond to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof.

[0116] The structural elements of the signal processing device 4 are not limited to those implemented by dedicated hardware, and the signal processing device 4 may be implemented by software, firmware, or a combination of software and firmware.

[0117] Software or firmware is stored in the computer's memory in the form of a program. A computer refers to hardware that executes a program, such as a CPU (Central Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor).

[0118] Figure 3 This is a hardware configuration diagram of a computer when the signal processing device 4 is implemented by software, firmware, or the like.

[0119] When the signal processing device 4 is implemented by software or firmware, the storage unit 11 is configured on the memory 31 of the computer. A program for causing the computer to execute each process in the map generation unit 13, the distance interval calculation unit 14, the height standard deviation calculation unit 15, the azimuth angle detection unit 16, and the collision determination unit 17 is stored in the memory 31. Then, the processor 32 of the computer executes the program stored in the memory 31.

[0120] In addition, Figure 2In FIG. 4 , an example is shown in which the components of the signal processing device 4 are respectively implemented by dedicated hardware. Figure 3 , an example is shown in which the signal processing device 4 is implemented by software or firmware. However, this is just an example, and some components of the signal processing device 4 may be implemented by dedicated hardware, and the remaining components may be implemented by software or firmware.

[0121] Next, Figure 1 The operation of the radar device shown will be described.

[0122] The radar device includes a transmitter (not shown) that radiates radio waves toward an object that exists around the vehicle. The transmitter that radiates radio waves toward the object may be a device outside the radar device.

[0123] The radio wave radiation method may be any method. For example, the radio wave radiation method may be an FMCW (Frequency Modulation Continuous Wave) method, an FMICW (Frequency Modulated and Interrupted Continuous Wave) method, or a pulse Doppler method.

[0124] The antenna 2 of the receiving unit 1 receives reflected waves reflected by objects existing around the vehicle.

[0125] The antenna 2 outputs reception signals r(t) of reflected waves at a plurality of times t to the ADC unit 3 .

[0126] The ADC unit 3 obtains reception signals r(t) of reflected waves at a plurality of times t from the antenna 2 .

[0127] The ADC unit 3 converts the received signal r(t) at each time t from an analog signal to a digital signal r D (t).

[0128] The ADC unit 3 converts the digital signal r D (t) The received signal as the reflected wave is output to the signal processing device 4.

[0129] Figure 4 : is a flowchart showing a signal processing method as a processing procedure of the signal processing device 4.

[0130] The digital signal r output from the ADC unit 3 D (t) is not only stored in the storage unit 11, but also provided to the map generation unit 13.

[0131] The map generation unit 13 obtains the digital signal r from the receiving unit 1 D(t) is the received signal of the reflected wave at time t.

[0132] The map generating unit 13 generates a map of the digital signal r by performing a range calculation in the range direction and the Doppler velocity direction. D (t) Perform Fourier transform to generate an RD graph showing the signal strength level of the received signal ( Figure 4 Step ST1).

[0133] Figure 5 1 is an explanatory diagram showing an example of the RD map generated by the map generating unit 13 .

[0134] exist Figure 5 In the graph, the horizontal axis is the relative speed between the vehicle and the object, i.e., the Doppler speed, and the vertical axis is the relative distance between the vehicle and the object. The RD graph is a two-dimensional graph showing the signal strength level SL of the received signal at the relative distance and relative speed. Figure 5 In the example, the difference in lightness and darkness indicates the difference in signal strength level. Figure 5 The RD diagram shown shows that there is 1 object around the vehicle.

[0135] Figure 5 The relative speeds in the RD diagram shown are divided into, for example, V numbers, and the relative distances in the RD diagram are divided into, for example, L numbers. V and L are integers of 1 or more, respectively.

[0136] The map generating unit 13 outputs the RD map to the distance interval calculating unit 14 , the height standard deviation calculating unit 15 , and the azimuth angle detecting unit 16 .

[0137] Here, the positional relationship between the vehicle and the object will be described. In addition, the relationship between the direct wave included in the reflected wave reflected by the object and the multipath wave included in the reflected wave will be described.

[0138] Figure 6 1 is an explanatory diagram showing the positional relationship between a vehicle and an overhead object and a reflected wave reflected by the overhead object. The overhead object is an object that exists above the vehicle and is not at a height at which the vehicle may collide.

[0139] exist Figure 6 In the example, at a height H above the ground R Antenna 2 is installed at the position, and the object above exists at a height H above the ground. T location.

[0140] exist Figure 6 In the example of FIG. 1 , the antenna 2 receives both the direct wave and the multipath wave. However, to simplify the description, only the multipath wave reflected by the ground mirror is shown. The reflection position of the multipath wave on the ground is at a distance R from the antenna 2. g，R The position of the object above is Rg，T By the way, the ground distance from antenna 2 to the object above is R g =R g，R +R g，T Hereinafter, the ground distance is referred to as the ground distance.

[0141] The elevation angle of the object above relative to the vehicle is θ EL , the incident angle of the multipath wave relative to the ground and the reflection angle of the multipath wave relative to the ground are θ EL，MP .

[0142] The reception signal s of the antenna 2 when the direct wave and the multipath wave overlap is expressed as in the following equation (1).

[0143]

[0144] In the formula (1), f0 is the center frequency of the radio wave radiated from the transmission unit (not shown) provided in the radar device, and c is the speed of light.

[0145] R S is the propagation distance of the direct wave, R MP is the propagation distance of the multipath wave, K MP is the reflection coefficient of the multipath wave.

[0146] The propagation distance R of multipath waves MP It is represented as the following formula (2).

[0147] R MP =R R +R T (2)

[0148] In formula (2), R T is the propagation distance from the object above to the ground, R R is the propagation distance from the ground to antenna 2.

[0149] According to the geometric relationship, the ground distance R between antenna 2 and the object above g It is represented as the following formula (3).

[0150] R g =R s cosθ EL =R g,R +R g，T (3)

[0151] The elevation angle θ of the object above relative to the vehicle EL As shown in the following equation (4), the incident angle θ of the multipath wave is EL，MP and the reflection angle θ of the multipath wave EL，MP They are respectively expressed as the following formula (5).

[0152]

[0153]

[0154] When the direct wave and the multipath wave interfere with each other due to the overlap of the direct wave and the multipath wave, the following equation (6) holds true.

[0155] R s -R MP =mλ (6)

[0156] In formula (6), m is an integer, m=0, ±1, ±2, ..., ±M.

[0157] By transforming equation (4), the propagation distance R of the direct wave is S It is represented as the following formula (7).

[0158] In addition, equation (5) can be transformed as in the following equation (8), and equation (8) can be transformed as in the following equation (9). Therefore, the propagation distance R of the multipath wave shown in equation (2) is MP It can be transformed as shown in the following formula (10).

[0159]

[0160]

[0161]

[0162]

[0163] By substituting equations (7) and (10) into equation (6), sinθ when the direct wave and the multipath wave interfere with each other is EL，m This is expressed as the following equation (11). Therefore, the elevation angle θ when the direct wave and the multipath wave interfere with each other is EL，m It is represented as the following formula (12).

[0164]

[0165]

[0166] By using the elevation angle θ when the direct wave and the multipath wave interfere with each other EL，m , the propagation distance R of the direct wave when the direct wave and the multipath wave interfere with each other S，m It is represented as the following formula (13).

[0167] In addition, by using the elevation angle θ EL，m, the ground distance R between antenna 2 and the object above when the direct wave and multipath wave interfere with each other g，m It is represented as the following formula (14).

[0168]

[0169]

[0170] Figure 7 It is an explanatory diagram showing the relationship between the ground distance and the power of the received signal s when the direct wave and the multipath wave overlap when the object is an object above, in front, or below.

[0171] The front object is an object that exists at a height that may collide with the vehicle. The lower object is an object that exists below the vehicle and is not an object that exists at a height that may collide with the vehicle.

[0172] exist Figure 7 In the figure, the solid line is the power of the received signal s corresponding to the ground distance related to the object above, the dashed line is the power of the received signal s corresponding to the ground distance related to the object in front, and the dotted line is the power of the received signal s corresponding to the ground distance related to the object below.

[0173] A peak point of the power of the received signal s is called a peak, and a zero point of the power of the received signal s is called a valley.

[0174] The distance interval between peaks is the distance interval when the direct wave and the multipath wave reinforce each other. The distance interval between valleys is the distance interval when the direct wave and the multipath wave weaken each other. Although the direct wave and the multipath wave also slightly reinforce each other within the distance interval between points near the peaks, in this specification, the distance interval between peaks is the distance interval when the direct wave and the multipath wave reinforce each other. In addition, although the direct wave and the multipath wave also slightly weaken each other within the distance interval between points near the valleys, in this specification, the distance interval between valleys is the distance interval when the direct wave and the multipath wave weaken each other.

[0175] like Figure 7 As shown in , the higher the height of the object, the longer the distance between the peaks. Figure 7 As shown, the shorter the ground distance between the antenna 2 and the object, the shorter the distance interval between the peaks.

[0176] Regarding the distance between valleys, the higher the altitude of the object is, the longer the distance between valleys is, and the shorter the ground distance between antenna 2 and the object is, the shorter the distance between valleys is.

[0177] Based on the increase or decrease in the power of the received signal s, the ground distance R when the direct wave and the multipath wave interfere with each other can be calculated. g，m (m=0, ±1, ±2,···,±M).

[0178] As shown in the following formula (15), it can be obtained based on the mth ground distance R g，m The associated elevation angle θ EL，m and the (m+1)th ground distance R g，m+1 The associated elevation angle θ EL，m+1 To calculate the distance interval ΔR when the direct wave and multipath wave interfere with each other m .

[0179]

[0180] The distance interval calculation unit 14 acquires the RD map from the map generation unit 13 .

[0181] The distance interval calculation unit 14 calculates the mutual reinforcement distance interval ΔR based on the RD map. m Or the distance interval ΔR m , as the distance interval at which the direct wave contained in the reflected wave and the multipath wave contained in the reflected wave interfere with each other ( Figure 4 Step ST2).

[0182] The distance interval calculation unit 14 calculates the distance interval ΔR m The distance interval information is output to the collision determination unit 17.

[0183] The calculation of the distance interval ΔR by the distance interval calculation unit 14 will be described in detail below. m Calculation processing.

[0184] The peak detection unit 14a calculates the V×L signal strength levels SL shown in the RD graph. 1，1 ~SL V，L The threshold Th related to CFAR CFAR Large signal strength level SL v，l Peak SL as the signal strength level peak，m To test.

[0185] V×L signal strength levels SL 1，1 ~SL V，L The ratio threshold Th CFAR Large signal strength level SL v，l Indicates the signal strength level of the reflected wave reflected by objects existing around the vehicle.

[0186] The peak detection unit 14a displays the peaks SL peak，m The relative velocity v and the peak SL peak，mThe detection information of the relevant relative distance l is output to the elevation angle calculation unit 14b and the propagation distance calculation unit 14c respectively.

[0187] The elevation angle calculation unit 14b acquires the detection information from the peak detection unit 14a.

[0188] The elevation angle calculation unit 14b calculates the elevation angle θ when the direct wave and the multipath wave interfere with each other based on the detection information. EL，m (m=0, ±1, ±2,···,±M).

[0189] Specifically, the elevation angle calculation unit 14 b performs arrival direction estimation processing using the correlation matrix and eigenvectors of the received signal s based on the detection information, thereby calculating the eigenvalues ​​of the correlation matrix.

[0190] The elevation angle calculation unit 14b estimates the number of arrival waves based on the number of eigenvalues ​​having a power greater than that of thermal noise, and calculates the elevation angle θ based on the number of arrival waves. EL，m (m=0, ±1, ±2,···,±M).

[0191] The elevation angle calculation unit 14b calculates the elevation angle θ EL，m The elevation angle information (m=0, ±1, ±2, ..., ±M) is output to the propagation distance calculation unit 14c and the distance interval calculation processing unit 14d, respectively.

[0192] The propagation distance calculation unit 14c acquires the detection information from the peak detection unit 14a, and acquires the elevation angle information from the elevation angle calculation unit 14b.

[0193] The propagation distance calculation unit 14c calculates the peak SL indicated by the detection information. peak，m The relative distance l is related to the propagation distance R of the direct wave S，m (m=0, ±1, ±2, ..., ±M) is substituted into the following equation (16), and the elevation angle θ indicated by the elevation angle information is EL，m Substituting into equation (16), the height H of the object is calculated T，m The height H of the antenna 2 is set R For example, it is stored in the internal memory of the propagation distance calculation unit 14c. EL，m contains errors, so sometimes the height H of the object T，m Contains errors.

[0194] H T,m =R S,m ×sin(θ EL,m )+H R (16)

[0195] The propagation distance calculation unit 14c substitutes the height H of the object T，m As H in formula (7)T , substitute the elevation angle θ EL，m As θ in formula (7) EL , the height H of the antenna 2 is set R Substituting into equation (7), the direct wave when the direct wave and the multipath wave interfere with each other is calculated. The propagation distance calculation unit 14c calculates the propagation distance R S，m The propagation distance information is output to the distance interval calculation processing unit 14d.

[0196] The distance interval calculation processing unit 14d obtains the elevation angle information from the elevation angle calculation unit 14b, and obtains the propagation distance information from the propagation distance calculation unit 14c.

[0197] The distance interval calculation processing unit 14d determines a plurality of propagation distances R indicated by the propagation distance information. S，0 ~R S，M The distance R between the mth ground and the g，m The relevant propagation distance R S，m and the distance R to the (m+1)th ground g，m+1 The relevant propagation distance R S，m+1 .

[0198] The distance interval calculation processing unit 14d calculates the mth propagation distance R S，m and the (m+1)th propagation distance R S，m+1 Substituting into equation (15), we can calculate the distance interval ΔR when the direct wave and the multipath wave interfere with each other. ，m .

[0199] The distance interval calculation processing unit 14d calculates the distance interval ΔR. m The distance interval information is output to the collision determination unit 17.

[0200] Here, the distance interval calculation processing unit 14d calculates the distance interval based on the mth propagation distance R S，m and the (m+1)th propagation distance R S，m+1 , calculate the distance interval ΔR m However, this is just an example, and the distance interval calculation processing unit 14d may also calculate the distance interval based on the m-th ground distance R g，m The associated elevation angle θ EL，m and the distance R to the (m+1)th ground g，m+1 The associated elevation angle θ EL，m+1 , calculate the distance interval ΔR m .

[0201] That is, the distance interval calculation processing unit 14d determines the plurality of elevation angles θ indicated by the elevation angle information. EL，1 ~θ EL，M The mth elevation angle θ EL，m and the (m+1)th elevation angle θEL，m+1 .

[0202] The distance interval calculation processing unit 14d calculates the m-th elevation angle θ EL，m , the (m+1)th elevation angle θ EL，m+1 , height H T，m and height H R Substitute them into equation (15) to calculate the distance interval ΔR when the direct wave and the multipath wave interfere with each other m .

[0203] The height standard deviation calculation unit 15 acquires the RD map from the map generation unit 13 .

[0204] The height standard deviation calculation unit 15 calculates the standard deviation H of the height where the object is located based on the RD map. std ( Figure 4 Step ST3).

[0205] The height standard deviation calculation unit 15 calculates the standard deviation H std The calculation result is output to the collision determination unit 17.

[0206] The standard deviation H calculated by the height standard deviation calculation unit 15 will be described in detail below. std Calculation processing.

[0207] The peak detection unit 15a detects the peak SL of the signal intensity level based on the RD graph generated by the graph generation unit 13, similarly to the peak detection unit 14a. peak，m .

[0208] The peak detection unit 15a displays the detected peaks SL peak，m The relative distances to the detected peaks SL peak，m The relevant relative speed detection information is output to the altitude calculation unit 15b.

[0209] The height calculation unit 15b acquires the detection information from the peak detection unit 15a.

[0210] The height calculation unit 15b calculates the propagation distance R of the direct wave when the direct wave and the multipath wave interfere with each other based on the detection information, similarly to the propagation distance calculation unit 14c. S，m (m=0,±1,±2,···,±M).

[0211] In addition, the altitude calculation unit 15b calculates the elevation angle θ when the direct wave and the multipath wave interfere with each other based on the detection information, similarly to the elevation angle calculation unit 14b. EL，m (m=0, ±1, ±2,···,±M).

[0212] The height calculation unit 15b calculates the propagation distance R S，m , elevation angle θEL，m and height H R Substitute into formula (16) to calculate the height H at multiple times T，m (m=0、±1、±2、···、±M). Height H R For example, it is stored in the internal memory of the altitude calculation unit 15b.

[0213] The height calculation unit 15b calculates the height H T，m The calculation result is output to the standard deviation calculation processing unit 15c.

[0214] The standard deviation calculation processing unit 15c obtains the height H from the height calculation unit 15b. T，m The calculation result of .

[0215] The standard deviation calculation processing unit 15c calculates the standard deviation based on the height H at multiple times as shown in the following formula (17): T，1 ~H T，M To calculate the standard deviation of height H std .

[0216] The standard deviation calculation processing unit 15c calculates the standard deviation H std The calculation result is output to the collision determination unit 17.

[0217] H std = std(H T，1 , H T，2 …,H T,M ) (17)

[0218] In formula (17), std() is used to calculate the height H in the brackets. T，1 ~H T，M function of the standard deviation of .

[0219] The azimuth angle detection unit 16 acquires the RD map from the map generation unit 13 .

[0220] The azimuth angle detection unit 16 detects the azimuth angle of the object relative to the vehicle based on the RD map.

[0221] The azimuth angle detection unit 16 outputs azimuth angle detection information indicating the azimuth angle of the object to the collision determination unit 17 .

[0222] Hereinafter, the azimuth angle detection process performed by the azimuth angle detection unit 16 will be described in detail.

[0223] The peak detection unit 16a detects the peak SL of the signal intensity level based on the RD graph generated by the graph generation unit 13, similarly to the peak detection unit 14a. peak，m .

[0224] The peak detection unit 16a displays the detected peaks SL peak，mThe relative distances to the detected peaks SL peak，m The relevant relative speed detection information is output to the azimuth angle detection processing unit 16b.

[0225] The azimuth detection processing unit 16b acquires the detection information from the peak detection unit 16a.

[0226] The azimuth angle detection processing unit 16 b calculates a plurality of azimuth angles of the object relative to the vehicle when the direct wave and the multipath wave interfere with each other based on the detection information.

[0227] Specifically, the azimuth detection processing unit 16 b performs arrival direction estimation processing using the correlation matrix and eigenvectors of the received signal s based on the detection information output from the peak detection unit 16 a , thereby calculating the eigenvalues ​​of the correlation matrix.

[0228] The azimuth detection processing unit 16 b estimates the number of arrival waves based on the number of eigenvalues ​​greater than the power of thermal noise, and estimates the azimuth of the object based on the number of arrival waves.

[0229] The azimuth detection processing unit 16 b outputs azimuth information indicating the azimuth of the object to the collision determination unit 17 .

[0230] The collision determination unit 17 obtains the distance interval ΔR from the distance interval calculation unit 14 m , obtain the standard deviation H of the height from the height standard deviation calculation unit 15 std , obtain the azimuth information from the azimuth detection unit 16.

[0231] If the azimuth angle indicated by the azimuth angle information matches the traveling direction of the vehicle, the collision determination unit 17 determines the direction of the vehicle based on the distance interval ΔR. m and the standard deviation of height H std , determine whether the object is at a height where the vehicle and the object may collide ( Figure 4 Step ST4).

[0232] The collision determination unit 17 outputs the determination result to the determination result output unit 5 .

[0233] Hereinafter, the determination process performed by the collision determination unit 17 will be described in detail.

[0234] The first score calculation unit 17 a determines whether the azimuth indicated by the azimuth information coincides with the traveling direction of the vehicle.

[0235] If the azimuth angle coincides with the vehicle's traveling direction, the first score calculation unit 17a sets a first threshold value Th indicating the boundary between the upper object and the front object for each ground distance r. UP，r , and a second threshold value Th indicating the boundary between the front object and the lower object DW，r . r is an integer greater than or equal to 1.

[0236] Hereinafter, the threshold setting process performed by the first score calculation unit 17 a will be described in detail.

[0237] like Figure 7 As shown in Figure 2, the higher the altitude of the object, the greater the distance between the direct wave and the multipath wave when they reinforce each other. m That is, the longer the distance between peaks. Figure 7 As shown, the shorter the ground distance between the antenna 2 and the object, the shorter the distance interval between the peaks.

[0238] Therefore, the first threshold value Th for the shorter ground distance r is UP，r and the second threshold Th DW，r On the other hand, the first threshold value Th for the longer ground distance r is UP，r and the second threshold Th DW，r are set to larger values ​​respectively.

[0239] For example, in the internal memory of the first score calculation unit 17a, the distance interval ΔR for each ground distance r when the object existing around the vehicle is a front object is stored as shown in the following formula (18): FRO，r .

[0240] For example, the height H of the front object T，FRO Than the height H of the roof of the vehicle CeI For example, the height H of the front object T，FRO Than the vehicle's lowest ground height H FLO High. FLO <H CeI .

[0241]

[0242] The first score calculation unit 17a uses the distance interval ΔR for each ground distance r as shown in the following equation (19): FRO，r , a first threshold Th representing the boundary between the upper object and the front object is set according to each ground distance r UP，r .

[0243] In addition, the first score calculation unit 17a uses the distance interval ΔR for each ground distance r as shown in the following equation (20): FRO，r , a second threshold Th representing the boundary between the front object and the lower object is set according to each ground distance r DW，r .

[0244] Th UP，r =P1×△R FRO,r (19)

[0245] ThDW,r =P2×ΔR FRO,r (20)

[0246] In equation (19), P1 is a coefficient greater than 1 and is used to make the first threshold value Th UP，r Greater than the distance interval ΔR associated with the frontal object FRO，r The coefficient of the expected distance interval ΔR FRO，r The corresponding height is higher than the height H of the roof of the vehicle CeI High, as close as possible to height H CeI Therefore, the first threshold Th UP，r For example Figure 8 As shown, it is set to be higher than the height H CeI Slightly higher height H T1 The corresponding distance interval. Figure 8 The first threshold value Th UP，r This is an illustration of an example of settings.

[0247] In equation (20), P2 is a coefficient smaller than 1 and is used to make the second threshold value Th DW，r Smaller than the distance interval ΔR associated with the frontal object FRO，r The coefficient of expectation and distance interval ΔR FRO，r The corresponding height is higher than the vehicle's lowest ground height H FLO Low, and as close as possible to the minimum ground height H FLO Therefore, the second threshold Th DW，r For example Fig. 9 As shown, it is set to be higher than the lowest ground height H FLO Slightly lower height H T1 'The corresponding distance interval. Fig. 9 The second threshold value Th DW，r This is an illustration of an example of settings.

[0248] The first score calculation unit 17 a obtains the distance interval ΔR from the distance interval calculation unit 14 m (m=0, ±1, ±2,···,±M).

[0249] The first score calculation unit 17a determines the distance intervals ΔR0 to ΔR M The distance interval ΔR corresponding to the ground distance r in r For example, if the distance interval ΔR represents m=5 m For example, if the peak with the shorter ground distance among the two peaks belongs to the ground distance of "3", the first score calculation unit 17a will calculate the distance interval ΔR of m=5. m Let r = 3, the distance interval ΔR r .

[0250] The first score calculation unit 17a sets the first threshold value Th UP，r and the second threshold Th DW，r Then, according to each ground distance r, the distance interval ΔR r and the first threshold Th UP，r For comparison, the distance interval ΔR r and the second threshold Th DW，r Make a comparison.

[0251] If the distance interval ΔR r than the first threshold Th UP，r If the first score is greater than the first value, the first score calculation unit 17a sets the value of the first score to the first value.

[0252] If the distance interval ΔR r is the first threshold Th UP，r Below and the distance interval is ΔR r is the second threshold Th DW，r As described above, the first score calculation unit 17a sets the value of the first score to the second value.

[0253] If the distance interval ΔR r than the second threshold value Th DW，r If the value of the first score is smaller than the value of the second score, the first score calculation unit 17a sets the value of the first score to the third value. First value>Second value>Third value.

[0254] The first score calculation unit 17a outputs the first score to the determination processing unit 17c.

[0255] Here, the first score calculation unit 17a calculates the value of the distance interval ΔR based on the distance interval ΔR. r Respectively with the first threshold Th UP，r and the second threshold Th DW，r However, this is just an example, and the first score calculation unit 17a may substitute the distance interval ΔR into the multi-order function for calculating the first score. r , distance interval ΔR r The larger the number, the larger the first score.

[0256] The second score calculation unit 17 b determines whether the azimuth indicated by the azimuth information coincides with the traveling direction of the vehicle.

[0257] If the azimuth angle coincides with the vehicle's traveling direction, the second score calculation unit 17b sets a third threshold value Th indicating the boundary between the upper object and the front object for each ground distance r. UP’，r and the fourth threshold Th representing the boundary between the front object and the lower object DW’，r .

[0258] Hereinafter, the threshold setting process performed by the second score calculation unit 17 b will be described in detail.

[0259] Fig.10 This is an explanatory diagram showing an example of the angle measurement values ​​of the elevation angles of the upper object, the front object, and the lower object as objects.

[0260] exist Fig.10 In the figure, the horizontal axis is the relative distance between the vehicle and the object, and the vertical axis is the elevation angle of the object.

[0261] △ is the measured value of the elevation angle of the object above, □ is the measured value of the elevation angle of the object in front, and ○ is the measured value of the elevation angle of the object below.

[0262] according to Fig.10 It can be seen that the higher the altitude of the object, the more likely it is that the elevation angle measurement accuracy will deteriorate under the influence of multipath waves.

[0263] Fig.11 It is an explanatory diagram showing an example of the standard deviation of the heights of the upper object, the front object, and the lower object as objects.

[0264] exist Fig.11 In , the horizontal axis is the relative distance between the vehicle and the object, and the vertical axis is the standard deviation of the height of the object.

[0265] △ is the standard deviation of the height of the object above, □ is the standard deviation of the height of the object in front, and ○ is the standard deviation of the height of the object below.

[0266] according to Fig.11 It can be seen that, similar to the angle measurement value of the elevation angle, the higher the height of the object, the easier it is for the standard deviation of the height of the object to deteriorate under the influence of multipath waves. Therefore, the standard deviation of the height of the object above is larger than the standard deviation of the height of the object in front. In addition, the standard deviation of the height of the object in front is larger than the standard deviation of the height of the object below.

[0267] exist Fig.11 In the example of FIG. 1 , a third threshold value Th is set between the standard deviation of the height of the object above and the standard deviation of the height of the object in front for each ground distance r. UP’，r In addition, for each ground distance r, a fourth threshold value Th is set between the standard deviation of the height of the front object and the standard deviation of the height of the lower object. DW’，r .

[0268] Desired third threshold Th UP’，r and the fourth threshold Th DW’，r Try to get as close as possible to the standard deviation of the height of the front object.

[0269] For example, the internal memory of the second score calculation unit 17b stores the standard deviation H of the height at each ground distance r when the object existing around the vehicle is a front object. FROstd，r .

[0270] The second score calculation unit 17b uses the standard deviation H of the height at each ground distance r as shown in the following equation (21): FROstd，r , a third threshold Th representing the boundary between the upper object and the front object is set according to each ground distance r UP’，r .

[0271] In addition, the second score calculation unit 17b uses the standard deviation H of the height at each ground distance r as shown in the following equation (22): FROstd，r , a fourth threshold Th representing the boundary between the front object and the lower object is set according to each ground distance r DW’，r .

[0272] Th UP′，r =P3×H FROstd,r (twenty one)

[0273] Th DW′,r =P4×H FROstd,r (twenty two)

[0274] In the formula (21), P3 is a coefficient greater than 1 and is used to make the third threshold value Th UP’，r Greater than the standard deviation H of the height associated with the frontal object FROstd，r The coefficient of . The expected third threshold Th UP’，r Than the height H of the roof of the vehicle CeI High, and as close as possible to height H CeI .

[0275] In equation (22), P4 is a coefficient smaller than 1 and is used to make the fourth threshold value Th DW’，r Smaller than the standard deviation H of the heights associated with the frontal objects FROstd，r The coefficient of . The expected fourth threshold Th DW’，r Than the vehicle's lowest ground height H FLO Low, and as close as possible to the minimum ground height H FLO .

[0276] The second score calculation unit 17 b obtains the standard deviation H of the height from the height standard deviation calculation unit 15 std The calculation result of .

[0277] The second score calculation unit 17b obtains the standard deviation H from the height std Corresponding to the ground distance r, the standard deviation H std Let the standard deviation of the ground distance r be H FROstd，r .

[0278] For example, if the standard deviation of the height H std The ground distance corresponds to the ground distance of r = 7, then the standard deviation H std Set as standard deviation H FROstd，7 If the standard deviation of the height H std The ground distance corresponds to the ground distance of r = 8, then the standard deviation H std Set as standard deviation H FROstd，8 .

[0279] The second score calculation unit 17b sets the third threshold value Th UP’，r and the fourth threshold Th DW’，r Then, for each ground distance r, the standard deviation H of the height FROstd，r and the third threshold Th UP’，r For comparison, the standard deviation of the height H FROstd，r and the fourth threshold Th DW’，r Make a comparison.

[0280] If the standard deviation of the height H FROstd，r than the third threshold Th UP’，r If the value of the second score is greater than the fourth value, the second score calculation unit 17b sets the value of the second score to the fourth value.

[0281] If the standard deviation of the height H FROstd，r is the third threshold Th UP’，r Below and the standard deviation of height H FROstd，r is the fourth threshold Th DW’，r As above, the second score calculation unit 17b sets the value of the second score to the fifth value.

[0282] If the standard deviation of the height H FROstd，r than the fourth threshold Th DW’，r If the value of the second score is smaller than the value of the sixth score, the second score calculation unit 17b sets the value of the second score to the sixth value. The fourth value>the fifth value>the sixth value.

[0283] The second score calculation unit 17b outputs the second score to the determination processing unit 17c.

[0284] Here, the second score calculation unit 17b calculates the standard deviation H of the height. FROstd，r and the third threshold Th UP’，r and the fourth threshold Th DW’，r However, this is just an example, and the second score calculation unit 17b may substitute the standard deviation H of the height into the multi-order function for calculating the second score. FROstd，r , standard deviation H FROstd，r The larger the number, the larger the second score.

[0285] The determination processing unit 17 c obtains the first score from the first score calculation unit 17 a and obtains the second score from the second score calculation unit 17 b .

[0286] The determination processing unit 17c calculates a comprehensive index value Ind which is the sum of the first score and the second score.

[0287] Here, the determination processing unit 17c calculates the comprehensive index value Ind by adding the first score to the second score. However, this is just an example, and the determination processing unit 17c may calculate the comprehensive index value Ind by weighted addition of the first score and the second score.

[0288] Fig.13 2 is a flowchart showing the determination processing of the determination processing unit 17 c.

[0289] The determination processing unit 17c compares the comprehensive index value Ind with the first comprehensive threshold value Th1.

[0290] If the comprehensive index value Ind is greater than the first comprehensive threshold value Th1 ( Fig.13 Step ST21: Yes), the determination processing unit 17c determines that the object existing around the vehicle is an upper object ( Fig.13 Step ST22).

[0291] That is, the determination processing unit 17c determines that the object does not exist at a height at which the vehicle and the object may collide.

[0292] If the comprehensive index value Ind is less than the first comprehensive threshold value Th1 ( Fig.13 In step ST21: No), the determination processing unit 17c compares the comprehensive index value Ind with the second comprehensive threshold value Th2.

[0293] If the comprehensive index value Ind is smaller than the second comprehensive threshold value Th2 ( Fig.13 Step ST23: Yes), the determination processing unit 17c determines that the object existing around the vehicle is a lower object ( Fig.13 Step ST24).

[0294] That is, the determination processing unit 17c determines that the object does not exist at a height at which the vehicle and the object may collide.

[0295] If the comprehensive index value Ind is greater than or equal to the second comprehensive threshold value Th2 ( Fig.13 Step ST23: No), the determination processing unit 17c determines that the object existing around the vehicle is a front object ( Fig.13 Step ST25).

[0296] That is, the determination processing unit 17c determines that the object exists at a height at which the vehicle and the object may collide.

[0297] The determination processing unit 17 c outputs the determination result to the determination result output unit 5 .

[0298] The determination result output unit 5 obtains the determination result of the collision determination unit 17 and outputs the determination result to, for example, a vehicle speed control device (not shown).

[0299] If the determination result of the collision determination unit 17 indicates that the object exists at a height at which the vehicle may collide, the vehicle speed control device controls the running speed of the vehicle, for example, so that the vehicle does not collide with the object.

[0300] Figure 1 The signal processing device 4 shown in the figure includes both a distance interval calculation unit 14 and a height standard deviation calculation unit 15. The collision determination unit 17 determines the distance interval ΔR calculated by the distance interval calculation unit 14 based on the distance interval ΔR. m and the standard deviation H calculated by the height standard deviation calculation unit 15 std , to determine whether the object exists at a height where the vehicle and the object may collide. However, this is just an example, and the signal processing device 4 may not include the distance interval calculation unit 14, and the collision determination unit 17 may be based on the standard deviation H calculated by the height standard deviation calculation unit 15. std , to determine whether the object exists at a height where the vehicle and the object may collide.

[0301] In this case, if the standard deviation of the height H FROstd，r than the third threshold Th UP’，r If the collision distance is large, the collision determination unit 17 determines that the object existing around the vehicle is an upper object. That is, the collision determination unit 17 determines that the object does not exist at a height at which the vehicle and the object may collide.

[0302] If the standard deviation of the height H FROstd，r than the fourth threshold Th DW’，r If the height of the object is smaller than that of the vehicle, the collision determination unit 17 determines that the object existing around the vehicle is a lower object. That is, the collision determination unit 17 determines that the object does not exist at a height at which the vehicle and the object may collide.

[0303] If the standard deviation of the height H FROstd，r is the third threshold Th UP’，r Below and the standard deviation of height H FROstd，r is the fourth threshold Th DW’，r In the above, the collision determination unit 17 determines that the object existing around the vehicle is a frontal object. In other words, the collision determination unit 17 determines that the object exists at a height at which the vehicle and the object may collide.

[0304] When the signal processing device 4 does not include the distance interval calculation unit 14 , the configuration can be simplified compared to a case where the signal processing device 4 includes both the distance interval calculation unit 14 and the height standard deviation calculation unit 15 .

[0305] In the above-mentioned first embodiment, the signal processing device 4 is configured to include: a map generation unit 13 that obtains a reception signal of a reflected wave from a receiving unit 1 that receives a reflected wave reflected by an object existing around a moving body, and generates a range Doppler map showing the signal strength level of the received signal; and a height standard deviation calculation unit 15 that calculates the standard deviation of the height at which the object is located based on the range Doppler map generated by the map generation unit 13. In addition, the signal processing device 4 includes a collision determination unit 17 that determines whether the object exists at a height at which the moving body and the object may collide based on the standard deviation calculated by the height standard deviation calculation unit 15. Therefore, the signal processing device 4 can determine whether the object exists at a height at which the moving body and the object may collide based on the reception signal of the reflected wave received by only one receiving unit in a multipath environment.

[0306] Furthermore, in the first embodiment, the signal processing device 4 is configured to include a distance interval calculation unit 14, which calculates the distance interval at which the direct wave from the object included in the reflected wave and the multipath wave from the object included in the reflected wave interfere with each other based on the range Doppler map generated by the map generation unit 13. Furthermore, in the signal processing device 4, the collision determination unit 17 determines whether the object exists at a height at which the moving body and the object may collide based on the distance interval calculated by the distance interval calculation unit 14 and the standard deviation calculated by the height standard deviation calculation unit 15. Therefore, compared with the case where the signal processing device 4 determines whether the object exists at a height at which the moving body and the object may collide based only on the standard deviation.

[0307] exist Figure 1 In the signal processing device 4 shown in FIG. 1 , the second score calculation unit 17 b of the collision determination unit 17 uses the standard deviation H of the height at each ground distance r. FROstd，r , respectively set the third threshold Th UP’，r and the fourth threshold Th DW’，r However, this is only an example, and the second score calculation unit 17b may also be Fig.12 As shown in FIG. 1 , the third threshold value Th is set using the standard deviation of the received signal power. UP’，r and the fourth threshold Th DW’，r .

[0308] Fig.12 This is an explanatory diagram showing an example of the standard deviation of the received signal power of the reflected wave of each of the upper object, the front object, and the lower object as an object.

[0309] exist Fig.12 In , the horizontal axis is the relative distance between the vehicle and the object, and the vertical axis is the standard deviation of the received signal power.

[0310] according to Fig.12 It can be seen that, similar to the standard deviation of height, the higher the height of the object, the easier it is for the standard deviation of the received signal power to deteriorate under the influence of multipath waves. Therefore, the standard deviation of the received signal power associated with the object above is greater than the standard deviation of the received signal power associated with the object in front. In addition, the standard deviation of the received signal power associated with the object in front is greater than the standard deviation of the received signal power associated with the object below.

[0311] exist Fig.12 In the example, a temporary threshold value Th is set between the standard deviation of the received signal power associated with the object above and the standard deviation of the received signal power associated with the object in front at each ground distance r. UP2，r In addition, for each ground distance r, a temporary threshold value Th is set between the standard deviation of the received signal power associated with the front object and the standard deviation of the received signal power associated with the lower object. DW，r2 .

[0312] The second score calculation unit 17b calculates the temporary threshold value Th by, for example, UP2，r Substituting into the following formula (23), the third threshold value Th is calculated: UP’，r .

[0313] In addition, the second score calculation unit 17b calculates the temporary threshold value Th by, for example, DW2，r Substituting into the following formula (24), the fourth threshold Th is calculated: DW’，r .

[0314] Th UP′,r =P5×Th UP2,r +P6 (23)

[0315] Th DW′，r =P7×Th DW2,r +P8 (24)

[0316] In equations (23) to (24), P5, P6, P7, and P8 are parameters for adjusting the temporary threshold value.

[0317] Implementation method 2.

[0318] In the second embodiment, the signal processing device 4 is described for a case where there are a plurality of objects having different azimuth angles relative to the vehicle.

[0319] Fig.14 This is a diagram showing the structure of a radar device according to the second embodiment.

[0320] Fig.15 This is a hardware configuration diagram showing the hardware of the signal processing device 4 according to the second embodiment.

[0321] Fig.14 The radar device shown includes a receiving unit 1 , a signal processing device 4 , and a determination result output unit 5 .

[0322] The signal processing unit 12 includes a map generating unit 13 , a distance interval calculating unit 14 , a height standard deviation calculating unit 15 , an azimuth angle detecting unit 16 , and a collision determining unit 18 .

[0323] The collision determination unit 18 is composed of, for example, Fig.15 The collision determination circuit 28 shown is implemented.

[0324] The collision determination unit 18 includes a first score calculation unit 18 a , a second score calculation unit 18 b , and a determination processing unit 18 c .

[0325] The collision determination unit 18 specifies the azimuths of each of the plurality of objects based on the azimuth information output from the azimuth detection unit 16 .

[0326] The collision determination unit 18 identifies an object whose azimuth angle coincides with the traveling direction of the vehicle among the plurality of objects.

[0327] The collision determination unit 18 determines whether the identified object is located at a height at which the vehicle and the object may collide based on the distance interval calculated by the distance interval calculation unit 14 and the standard deviation calculated by the height standard deviation calculation unit 15 .

[0328] The collision determination unit 18 does not perform determination processing on an object whose azimuth angle does not coincide with the traveling direction of the vehicle.

[0329] The collision determination unit 18 outputs the determination result to the determination result output unit 5 .

[0330] The first score calculation unit 18 a specifies the azimuths of each of the plurality of objects based on the azimuth information output from the azimuth detection unit 16 , and specifies an object whose azimuth coincides with the traveling direction of the vehicle among the plurality of objects.

[0331] The first score calculation unit 18 a calculates a first score for the specified object based on the distance interval calculated by the distance interval calculation unit 14 .

[0332] The first score calculation unit 18 a outputs the first score to the determination processing unit 18 c .

[0333] The second score calculation unit 18 b specifies the azimuths of each of the plurality of objects based on the azimuth information output from the azimuth detection unit 16 , and specifies an object whose azimuth coincides with the traveling direction of the vehicle among the plurality of objects.

[0334] The second score calculation unit 18 b calculates a second score for the specified object based on the standard deviation calculated by the height standard deviation calculation unit 15 .

[0335] The second score calculation unit 18b outputs the second score to the determination processing unit 18c.

[0336] The determination processing unit 18c and Figure 1 The determination processing unit 17 c shown similarly calculates a comprehensive index value which is the sum of the first score calculated by the first score calculation unit 18 a and the second score calculated by the second score calculation unit 18 b .

[0337] The determination processing unit 18 c determines whether or not the object is at a height at which the vehicle and the object may collide, based on the comparison result between the comprehensive index value and the threshold value.

[0338] exist Fig.14 In the above, it is assumed that the storage unit 11, the map generation unit 13, the distance interval calculation unit 14, the height standard deviation calculation unit 15, the azimuth angle detection unit 16 and the collision determination unit 18 as the structural elements of the signal processing device 4 are respectively Fig.15 Specifically, it is assumed that the signal processing device 4 is implemented by the storage circuit 21 , the map generation circuit 23 , the distance interval calculation circuit 24 , the height standard deviation calculation circuit 25 , the azimuth angle detection circuit 26 , and the collision determination circuit 28 .

[0339] The map generation circuit 23, the distance interval calculation circuit 24, the height standard deviation calculation circuit 25, the azimuth angle detection circuit 26 and the collision judgment circuit 28 respectively correspond to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof.

[0340] The structural elements of the signal processing device 4 are not limited to those implemented by dedicated hardware, and the signal processing device 4 may be implemented by software, firmware, or a combination of software and firmware.

[0341] When the signal processing device 4 is implemented by software or firmware, the storage unit 11 stores Figure 3 The computer is configured on the memory 31 shown in FIG. A program for causing the computer to execute the processing of the map generation unit 13, the distance interval calculation unit 14, the height standard deviation calculation unit 15, the azimuth detection unit 16 and the collision determination unit 18 is stored in the memory 31. Figure 3 The processor 32 of the illustrated computer executes the program stored in the memory 31 .

[0342] In addition, Fig.15In FIG. 4 , an example is shown in which the components of the signal processing device 4 are respectively implemented by dedicated hardware. Figure 3 , an example is shown in which the signal processing device 4 is implemented by software or firmware. However, this is just an example, and some components of the signal processing device 4 may be implemented by dedicated hardware, and the remaining components may be implemented by software or firmware.

[0343] Fig.16 This is an explanatory diagram showing a plurality of objects having different azimuth angles relative to a vehicle.

[0344] exist Fig.16 In the example, there are two objects, one of which is an object above the vehicle with an azimuth angle that matches the vehicle's direction of travel. The propagation distance of the direct wave from the object above is R S , the propagation distance of the multipath wave from the object above is R MP .

[0345] The other object is an object whose azimuth is not consistent with the direction of travel of the vehicle. The distance between the vehicle and the other object is R AZ .

[0346] exist Fig.16 In the example of , the reflected waves received by antenna 2 include direct waves from the upper object, multipath waves from the upper object, and reflected waves from another object.

[0347] In this case, the reception signal s' of the antenna 2 is expressed as in the following equation (25).

[0348]

[0349] In formula (25), K AZ is the reflection coefficient.

[0350] When the direct wave from the upper object overlaps with the multipath wave from the upper object and causes the direct wave and the multipath wave to interfere with each other, the following equation (26) holds. When the multipath wave from the upper object overlaps with the reflected wave from another object and causes the multipath wave and the reflected wave from another object to interfere with each other, the following equation (27) holds.

[0351] In addition, when a direct wave from an upper object and a reflected wave from another object interfere with each other, the following equation (28) holds true.

[0352] R s -R MP =m1λ (m1=0,±1,±2,…) (26)

[0353] R MP -RAZ =m2λ(m2=0,±1,±2,…) (27)

[0354] R s -R AZ =m3λ(m3=0,±1,±2,…) (28)

[0355] The distance interval ΔR when the direct wave from the object above and the multipath wave from the object above interfere with each other m1 , can be expressed as the following formula (29) according to the distance R from the m1th ground surface g，m1 The associated elevation angle θ EL，m1 and the distance R to the (m1+1)th ground g，m1+1 The associated elevation angle θ EL，m1+1 Perform calculations.

[0356]

[0357] The distance ΔR when the direct wave from the object above interferes with the reflected wave from another object m3 , can be calculated based on the m3th ground distance R as shown in the following formula (30): g，m3 The associated elevation angle θ EL，m3 and the distance R from the (m3+1)th ground g，m3+1 The associated elevation angle θ EL，m3+1 Perform calculations.

[0358]

[0359] Next, Fig.14 The operation of the radar device shown in FIG. Figure 1 The radar devices shown are the same, so only the operation of the collision determination unit 18 will be described here.

[0360] The first score calculation unit 18 a of the collision determination unit 18 acquires the azimuth angle information from the azimuth angle detection unit 16 .

[0361] The first score calculation unit 18 a specifies the azimuths of each of the plurality of objects based on the azimuth information.

[0362] The first score calculation unit 18 a determines whether the azimuth angle of each object coincides with the traveling direction of the vehicle.

[0363] If there is an object whose azimuth angle coincides with the traveling direction of the vehicle among the plurality of objects, the first score calculation unit 18a sets a first threshold value Th for the object whose azimuth angle coincides with the traveling direction of the vehicle. UP，r and the second threshold Th DW，r The first score calculation unit 18a calculates the first threshold value ThUP，r The setting method of Figure 1 The first score calculation unit 17a shown in FIG. UP，r The setting method is the same as above.

[0364] The first score calculation unit 18a calculates the score of an object whose azimuth angle coincides with the direction of travel of the vehicle by comparing the score with the Figure 1 The first score calculation unit 17a shown in the figure calculates the first score in the same manner.

[0365] The first score calculation unit 18 a does not calculate the first score for an object whose azimuth angle does not coincide with the traveling direction of the vehicle.

[0366] exist Fig.16 In the example of , the first score calculation unit 18a calculates the first score for the upper object, and does not calculate the first score for other objects.

[0367] The second score calculation unit 18 b acquires the azimuth information from the azimuth detection unit 16 .

[0368] Similar to the first score calculation unit 18 a , the second score calculation unit 18 b specifies the azimuths of each of the plurality of objects based on the azimuth information, and determines whether the azimuth of each object coincides with the traveling direction of the vehicle.

[0369] If there is an object whose azimuth angle coincides with the traveling direction of the vehicle among the plurality of objects, the second score calculation unit 18b sets the third threshold value Th for the object whose azimuth angle coincides with the traveling direction of the vehicle. UP’，r and the fourth threshold Th DW’，r The second score calculation unit 18b calculates the third threshold value Th UP’，r The setting method of Figure 1 The second score calculation unit 17b shown in FIG. UP’，r The setting method is the same as above.

[0370] The second score calculation unit 18b calculates the object whose azimuth angle is consistent with the vehicle's traveling direction by comparing the Figure 1 The first score calculation unit 17a shown calculates the second score in the same manner.

[0371] The second score calculation unit 18 b does not calculate the second score for an object whose azimuth angle does not coincide with the traveling direction of the vehicle.

[0372] exist Fig.16 In the example of , the second score calculation unit 18b calculates the second score for the upper object, and does not calculate the second score for other objects.

[0373] The determination processing unit 18c and Figure 1The determination processing unit 17 c shown similarly calculates a comprehensive index value which is the sum of the first score calculated by the first score calculation unit 18 a and the second score calculated by the second score calculation unit 18 b .

[0374] The determination processing unit 18c and Figure 1 Similarly, the determination processing unit 17 c shown determines whether or not an object is present at a height at which the vehicle and the object may collide, based on the comparison result between the comprehensive index value and the threshold value.

[0375] In the above embodiment 2, Fig.14 The signal processing device 4 shown is configured such that, when there are multiple objects around the moving body, the collision determination unit 18 determines among the multiple objects an object whose azimuth detected by the azimuth detection unit 16 is consistent with the moving direction of the moving body, and determines whether the determined object exists at a height that may collide with the moving body. Fig.14 The signal processing device 4 shown is Figure 1 Similarly, the signal processing device 4 shown can determine whether an object exists at a height where a moving body and the object may collide based on the reception signal of the reflected wave received by only one receiving unit in a multipath environment. Fig.14 The signal processing device 4 shown in the figure makes determination only on an object that may collide with the moving body when a plurality of objects exist around the moving body, and can omit unnecessary determination processing.

[0376] In addition, the present disclosure allows free combination of the various embodiments, modification of arbitrary components of the various embodiments, or omission of arbitrary components in the various embodiments.

[0377] Industrial Applicability

[0378] The present disclosure is suitable for a signal processing device, a signal processing method, and a radar device.

[0379] Description of Reference Numerals

[0380] 1 receiving unit, 2 antenna, 3 ADC unit, 4 signal processing device, 5 determination result output unit, 11 storage unit, 12 signal processing unit, 13 map generation unit, 14 distance interval calculation unit, 14a peak detection unit, 14b elevation calculation unit, 14c propagation distance calculation unit, 14d distance interval calculation processing unit, 15 height standard deviation calculation unit, 15a peak detection unit, 15b height calculation unit, 15c standard deviation calculation processing unit, 16 azimuth detection unit, 16a peak detection unit, 16b Azimuth angle detection processing unit, 17 collision determination unit, 17a first score calculation unit, 17b second score calculation unit, 17c determination processing unit, 18 collision determination unit, 18a first score calculation unit, 18b second score calculation unit, 18c determination processing unit, 21 storage circuit, 23 map generation circuit, 24 distance interval calculation circuit, 25 height standard deviation calculation circuit, 26 azimuth angle detection circuit, 27 collision determination circuit, 28 collision determination circuit, 31 memory, 32 processor.

Claims

1. A signal processing device comprising: a map generating unit for acquiring a reception signal of a reflected wave from a receiving unit that receives a reflected wave reflected by an object existing around the moving body, and generating a range Doppler map showing a signal strength level of the received signal; a height standard deviation calculation unit that calculates a standard deviation of a height at which the object is located based on the range Doppler map generated by the map generation unit; and A collision determination unit determines whether the object is present at a height at which the moving body and the object may collide based on the standard deviation calculated by the height standard deviation calculation unit.

2. The signal processing device according to claim 1, characterized in that The height standard deviation calculation unit calculates the heights of the object at a plurality of times based on the range Doppler map generated by the map generation unit, and calculates the standard deviation of the height from the heights at the plurality of times.

3. The signal processing device according to claim 1, characterized in that: The signal processing device includes a distance interval calculation unit that calculates a distance interval at which a direct wave from the object included in the reflected wave and a multipath wave from the object included in the reflected wave interfere with each other based on the range Doppler map generated by the map generation unit. The collision determination unit determines whether the object exists at a height at which the moving body and the object may collide based on the distance interval calculated by the distance interval calculation unit and the standard deviation calculated by the height standard deviation calculation unit.

4. The signal processing device according to claim 3, characterized in that: The distance interval calculation unit calculates a distance interval at which the direct wave and the multipath wave reinforce each other or a distance interval at which the direct wave and the multipath wave weaken each other as a distance interval at which the direct wave and the multipath wave interfere with each other.

5. The signal processing device according to claim 3, characterized in that: The collision determination unit calculates a first score based on the distance interval calculated by the distance interval calculation unit, calculates a second score based on the standard deviation calculated by the height standard deviation calculation unit, calculates a comprehensive index value that is the sum of the first score and the second score, and determines whether the object is at a height at which the moving body and the object may collide based on a comparison result of the comprehensive index value and a threshold value.

6. The signal processing device according to claim 1, characterized in that: The signal processing device includes an azimuth angle detection unit configured to detect an azimuth angle of the object relative to the moving body based on the range Doppler map generated by the map generation unit. The collision determination unit determines whether the object is present at a height at which the moving body and the object may collide only when the azimuth detected by the azimuth detection unit coincides with the traveling direction of the moving body.

7. The signal processing device according to claim 6, characterized in that: When there are multiple objects around the moving body, the collision determination unit determines an object whose azimuth detected by the azimuth detection unit is consistent with the moving direction of the moving body among the multiple objects, and determines whether the determined object exists at a height that may collide with the moving body.

8. A signal processing method, wherein: A map generating unit acquires a reception signal of a reflected wave from a receiving unit that receives a reflected wave reflected by an object existing around the moving body, and generates a range Doppler map showing a signal strength level of the received signal. The height standard deviation calculation unit calculates the standard deviation of the height at which the object is located based on the range Doppler map generated by the map generation unit. The collision determination unit determines whether the object is present at a height at which the moving body and the object may collide based on the standard deviation calculated by the height standard deviation calculation unit.

9. A radar device comprising: a receiving unit that receives a reflected wave reflected by an object existing around the moving body; a map generating unit that acquires the reception signal of the reflected wave from the receiving unit and generates a range Doppler map showing a signal strength level of the reception signal; a height standard deviation calculation unit that calculates a standard deviation of a height at which the object is located based on the range Doppler map generated by the map generation unit; as well as A collision determination unit determines whether the object is present at a height at which the moving body and the object may collide based on the standard deviation calculated by the height standard deviation calculation unit.

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