SIGNAL PROCESSING EQUIPMENT, SIGNAL PROCESSING METHOD AND RADAR EQUIPMENT

Abstract

A signal processing device (4) is configured to include a map generation unit (13) for acquiring a received signal of a reflected wave from a receiving unit (1) which receives the reflected wave from an object located in the vicinity of a mobile object, and for generating a distance Doppler map indicating a signal strength level of the received signal, and an altitude standard deviation calculation unit (15) for calculating a standard deviation of an altitude at which the object is located, based on the distance Doppler map generated by the map generation unit (13).Furthermore, the signal processing device (4) includes a collision detection unit (17) to determine whether or not the object is at a height where there is a possibility of collision between the mobile object and the object, based on the standard deviation calculated by the height standard deviation calculation unit (15).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a signal processing device, a signal processing method and a radar device. BACKGROUND TO THE STATE OF THE ART

[0002] There is a radar device (hereinafter referred to as "conventional radar device") that determines whether or not an object exists at an altitude where there is a possibility of collision between a mobile object and the object. There is a driving assistance system that has the function of decelerating a mobile object when a determination result from a conventional radar device is acquired, and the determination result indicates that an object exists at an altitude where there is a possibility of collision. In a multi-path environment where a multi-path wave from a target object is included in a reflected wave from the target object in addition to a direct wave from the target object, the detection accuracy of the altitude of the target object by the conventional radar device deteriorates, and as a result, the conventional radar device may make an erroneous determination.

[0003] For example, Patent Literature 1 discloses a radar device that detects the altitude of a target object, which is an object.

[0004] The radar device disclosed in Patent Literature 1 includes a plurality of sensor units, a variance calculation unit, and a data selection unit to suppress deterioration in altitude detection accuracy in a multi-path environment. Each sensor unit includes a transmitting and receiving unit that receives a reflected wave from a target object, and a position measuring unit that measures an altitude of the target object based on a received signal of the reflected wave. The variance calculation unit calculates an altitude variance measured by the sensor unit included in any combination including all or some of the plurality of sensor units.The data selection unit selects a combination that minimizes the variance calculated by the variance calculation unit from a plurality of combinations, and calculates an average value of the altitudes measured by the sensor units included in the selected combination as the altitude of the target object. REFERENCE LISTPATENT LITERATURE

[0005] Patent Literature 1: JP 2012-189474 A SUMMARY OF THE INVENTIONTECHNICAL PROBLEM

[0006] The radar device disclosed in Patent Literature 1 has the problem that it is necessary to include a plurality of sensor units.

[0007] The present disclosure has been made to solve the above problems, and an object of the present disclosure is to provide a signal processing device capable of determining, based on a reception signal of a reflected wave received by only one receiving unit in a multi-path environment, whether or not an object is present at a height at which there is a possibility of collision between a mobile object and the object. SOLUTION TO THE PROBLEM

[0008] A signal processing device according to the present disclosure includes a map generation unit for acquiring a reception signal of a reflected wave from a receiving unit that receives the reflected wave from an object present in the vicinity of a mobile object, and generating a range Doppler map indicating a signal strength level of the reception signal, and an altitude standard deviation calculation unit for calculating a standard deviation of an altitude at which the object is located based on the range Doppler map generated by the map generation unit.Furthermore, the signal processing device comprises a collision determination unit for determining whether or not the object is located at an altitude at which there is a possibility of collision between the mobile object and the object, based on the standard deviation calculated by the altitude standard deviation calculation unit. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0009] According to the present disclosure, in a multi-path environment, it is possible to determine whether an object is located at a height where there is a possibility of collision between a mobile object and the object based on a reception signal of a reflected wave received by only one reception unit. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a configuration diagram illustrating a radar device according to a first embodiment. Fig. 2 is a hardware configuration diagram illustrating hardware of a signal processing device 4 according to the first embodiment. Fig. 3 is a hardware configuration diagram of a computer in a case where the signal processing device 4 is implemented by software, firmware, or the like. Fig. 4 is a flowchart showing a signal processing method which is a processing flow of the signal processing device 4. Fig. 5 is an explanatory diagram showing an example of an RD map generated by a map generating unit 13. Fig. 6 is an explanatory diagram showing a positional relationship between a vehicle and an upper object and a wave reflected from the upper object. Fig. 7 is an explanatory diagram illustrating the relationship between a ground distance in a case where an object is an upper object, a front object, or a lower object, and the strength of a reception signal in a case where a direct wave and a multipath wave are superimposed on each other. Fig. Fig. 8 is an explanatory diagram showing a setting example of a first threshold value Th UP,r shows. Fig. Fig. 9 is an explanatory diagram showing an example of setting a second threshold value Th Dw,r shows. Fig. 10 is an explanatory diagram showing an example of angle measurement values ​​of elevation angles of an upper object, a front object, and a lower object, which are objects. Fig. 11 is an explanatory diagram showing an example of standard deviations of heights of an upper object, a front object, and a lower object, which are objects. Fig. 12 is an explanatory diagram showing an example of standard deviations of a received signal strength of respective reflected waves of an upper object, a front object, and a lower object, which are objects. Fig. 13 is a flowchart showing a determination processing of a determination processing unit 17c. Fig. 14 is a configuration diagram illustrating a radar device according to a second embodiment. Fig. 15 is a hardware configuration diagram showing the hardware of the signal processing device 4 according to the second embodiment. Fig. 16 is an explanatory diagram showing a plurality of objects having different azimuth angles with respect to a vehicle. DESCRIPTION OF THE EMBODIMENTS

[0010] In order to further explain the present disclosure, modes for carrying out the present disclosure will be described below with reference to the accompanying drawings. First embodiment

[0011] Fig. 1 is a configuration diagram illustrating a radar device according to a first embodiment.

[0012] Fig. 2 is a hardware configuration diagram illustrating hardware of a signal processing device 4 according to the first embodiment.

[0013] The Fig. The radar device shown in Figure 1 comprises a receiving unit 1, the signal processing unit 4 and a determination result output unit 5.

[0014] The receiving unit 1 comprises an antenna 2 and an analog-to-digital converter unit (hereinafter referred to as “ADC unit”) 3.

[0015] The receiving unit 1 receives a reflected wave from an object located in the vicinity of a mobile object. The receiving unit 1 outputs received signals of reflected waves to the signal processing device 4 at a plurality of times. Examples of a mobile object are a vehicle, a train, a ship, or a person. Other examples of the vehicle are a four-wheeled automobile, a motorcycle, a bicycle, or an electrically powered stationary two-wheeler.

[0016] At the Fig. For the sake of simplicity, the radar system shown in Figure 1 is explained assuming that the mobile object is a vehicle. The mobile object could be, for example, a train or a ship.

[0017] The antenna 2 receives a reflected wave from an object and outputs a received signal of a reflected wave to the ADC unit 3.

[0018] The ADC unit 3 acquires reception signals of reflected waves at a plurality of times from the antenna 2.

[0019] The ADC unit 3 converts a received signal at any time from an analog signal into a digital signal with a preset sampling frequency.

[0020] The ADC unit 3 outputs the digital signal to the signal processing device 4 as a reception signal of the reflected wave.

[0021] The signal processing device 4 comprises a storage unit 11 and a signal processing unit 12.

[0022] Based on the digital signal output from the ADC unit 3, the signal processing device 4 determines whether or not an object is located at a height at which there is a possibility of collision between a vehicle as a moving object and the object.

[0023] The signal processing device 4 outputs a determination result to the determination result output unit 5.

[0024] Examples of objects located at a height where there is a possibility of collision with the vehicle include another vehicle, a pedestrian, or a guardrail. Examples of objects not located at a height where there is a possibility of collision with the vehicle include a manhole cover, a grating, a sign, and a pedestrian bridge.

[0025] The storage unit 11 is, for example, Fig. 2 illustrated memory circuit 21 is implemented.

[0026] In addition to each digital signal output from the ADC unit 3, the storage unit 11 stores a determination result and the like from the signal processing unit 12.

[0027] The signal processing unit 12 includes a map generation unit 13, a distance interval calculation unit 14, an altitude standard deviation calculation unit 15, an azimuth angle detection unit 16, and a collision determination unit 17.

[0028] The card generation unit 13 is, for example, Fig. 2 illustrated map generation circuit 23 is implemented.

[0029] The map generation unit 13 acquires from the receiving unit 1 digital signals acquired at a plurality of times as reception signals of reflected waves at a plurality of times.

[0030] The map generation unit 13 generates a range Doppler map (hereinafter referred to as an "RD map") indicating a signal strength level of the received signal from the digital signal. The RD map is a two-dimensional map that indicates the signal strength level of the received signal according to a relative distance between the vehicle and the object and a relative speed between the vehicle and the object.

[0031] The map generation unit 13 outputs the RD map to the distance interval calculation unit 14, the altitude standard deviation calculation unit 15, and the azimuth angle detection unit 16, respectively.

[0032] The distance interval calculation unit 14 is implemented, for example, by a distance interval calculation circuit 24 as shown in Fig. 2 shown.

[0033] The distance interval calculation unit 14 includes a peak detection unit 14a, an elevation angle calculation unit 14b, a travel time distance calculation unit 14c, and a distance interval calculation processing unit 14d.

[0034] Based on the RD map generated by the map generation unit 13, the distance interval calculation unit 14 calculates a distance interval where a direct wave from an object contained in a reflected wave and a multipath wave from the object contained in the reflected wave interfere with each other. As the distance interval where the direct wave and the multipath wave interfere with each other, there is a distance interval where the direct wave and the multipath wave reinforce each other, or a distance interval where the direct wave and the multipath wave attenuate each other.

[0035] The distance interval calculation unit 14 outputs distance interval information indicating the calculated distance interval to the collision determination unit 17.

[0036] The peak detection unit 14a detects a peak of the signal strength level based on the RD map generated by the map generation unit 13.

[0037] Specifically, the peak detection unit 14a detects a signal strength level greater than a threshold Th CFAR , which refers to a constant false alarm rate (CFAR), among a plurality of signal strength levels indicated as a peak of the signal strength level in the RD map generated by the map generation unit 13. Among the plurality of signal strength levels displayed in the RD map, the relative distance relating to a signal strength level greater than the threshold Th CFAR, the relative distance between the vehicle and the object, and the relative speed, which refers to a signal strength level greater than the threshold Th CFAR , is the relative speed between the vehicle and the object.

[0038] The peak detection unit 14a outputs detection information each indicating the relative distance with respect to the detected peak and the relative speed with respect to the detected peak to the elevation angle calculation unit 14b and the travel time calculation unit 14c, respectively.

[0039] The elevation angle calculation unit 14b calculates a plurality of elevation angles of the object with respect 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 14a.

[0040] Specifically, the elevation angle calculation unit 14b calculates an eigenvalue of a correlation matrix by performing arrival direction detection processing using a correlation matrix and an eigenvector of the received signal based on the detection information output from the peak detection unit 14a.

[0041] The elevation angle calculation unit 14b determines the number of incoming waves based on the number of eigenvalues ​​greater than the thermal noise intensity, and determines the elevation angle of the object based on the number of incoming waves. For example, a multiple signal classification (MUSIC) method or signal parameter determination using a rotation invariant technique (ESPRIT) method can be used for the arrival direction determination processing. The MUSIC method or the ESPRIT method can be used to determine the elevation angle of the object.

[0042] The elevation angle calculation unit 14b outputs the elevation angle information indicating the calculated elevation angle to the travel time calculation unit 14c and the distance interval calculation processing unit 14d, respectively.

[0043] In addition, the elevation angle calculation unit 14b may cause the elevation angle information to be stored in the storage unit 11.

[0044] The travel time calculation unit 14c calculates a plurality of travel times 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 14a and the elevation angle information output from the elevation angle calculation unit 14b.

[0045] The travel time calculation unit 14c outputs travel time information indicating the plurality of calculated travel time distances to the distance interval calculation processing unit 14d.

[0046] The distance interval calculation processing unit 14d calculates, as the distance interval at which the direct wave from the object and the multipath wave from the object interfere with each other, a difference between an m-th (m is an integer of 1 or more) travel time and an (m+1)-th travel time among a plurality of travel time distances indicated by the travel time information output from the travel time calculation unit 14c. The m-th travel time is a travel time that refers to the m-th longest relative distance among a 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 travel time is a travel time that refers to the (m+1)-th longest relative distance among the plurality of relative distances between the vehicle and the object.

[0047] Instead of calculating the difference between the mth propagation distance and the (m+1)th propagation distance as the distance interval at which mutual interference occurs, the distance interval calculation processing unit 14d may calculate a distance interval at which mutual interference occurs from an mth elevation angle and an (m+1)th elevation angle among a plurality of elevation angles indicated by the elevation angle information output from the elevation angle calculation unit 14b. The mth elevation angle is an elevation angle that refers to 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 elevation angle is an elevation angle that refers to the (m+1)th longest relative distance among the plurality of relative distances between the vehicle and the object.

[0048] The distance interval calculation processing unit 14d outputs distance interval information indicating the distance interval to the collision determination unit 17.

[0049] The altitude standard deviation calculation unit 15 is, for example, represented by an altitude standard deviation calculation unit 25 in Fig. 2, implemented.

[0050] The altitude standard deviation calculation unit 15 includes a peak detection unit 15a, an altitude calculation unit 15b, and a standard deviation calculation processing unit 15c.

[0051] The altitude standard deviation calculation unit 15 calculates the standard deviation of an altitude at which the object is located based on the RD map generated by the map generation unit 13.

[0052] The altitude standard deviation calculation unit 15 outputs a calculation result of the standard deviation to the collision determination unit 17.

[0053] The peak detection unit 15a detects a peak of the signal strength level based on the RD map generated by the map generation unit 13, similarly to the peak detection unit 14a.

[0054] The peak detection unit 15a outputs detection information each indicating the relative distance with respect to the detected peak and the relative speed with respect to the detected peak to the altitude calculation unit 15b.

[0055] The altitude calculation unit 15b calculates an altitude at each of a plurality of times at which the object exists, based on the detection information output from the peak detection unit 15a.

[0056] The altitude calculation unit 15b outputs altitude information indicating the altitudes at a plurality of times to the standard deviation calculation processing unit 15c.

[0057] The standard deviation calculation processing unit 15c calculates a standard deviation of the altitude from the altitudes at the plurality of times indicated by the altitude information indicated by the altitude calculation unit 15b.

[0058] The standard deviation calculation processing unit 15 outputs a calculation result of the standard deviation to the collision determination unit 17.

[0059] The azimuth angle detection unit 16 is, for example, Fig. 2 shown azimuth angle detection circuit 26 is realized.

[0060] The azimuth angle detection unit 16 includes a peak detection unit 16a and an azimuth angle detection processing unit 16b.

[0061] The azimuth angle detection unit 16 detects an azimuth angle of an object with respect to the vehicle based on the RD map generated by the map generation unit 13.

[0062] The azimuth angle detection unit 16 outputs azimuth angle detection information indicating the azimuth angle of the object to the collision determination unit 17.

[0063] The peak detection unit 16a detects a peak of the signal strength level based on the RD map generated by the map generation unit 13, similarly to the peak detection unit 14a.

[0064] The peak detection unit 16a outputs detection information each indicating the relative distance with respect to the detected peak and the relative speed with respect to the detected peak to the azimuth angle detection processing unit 16b.

[0065] In the signal processing device 4, shown in Fig. 1, the distance interval calculation unit 14 includes the peak detection unit 14a, the altitude standard deviation calculation unit 15 includes the peak detection unit 15a, and the azimuth angle detection unit 16 includes the peak detection unit 16a. However, this is merely an example, and the signal processing device 4 may include a single peak detection unit, and the distance interval calculation unit 14, the altitude standard deviation calculation unit 15, and the azimuth angle detection unit 16 may utilize detection information output from the single peak detection unit.

[0066] The azimuth angle detection processing unit 16b calculates a plurality of elevation angles of the object with respect 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 16a.

[0067] Specifically, the azimuth angle detection processing unit 16b calculates the eigenvalue of a correlation matrix by performing the arrival direction detection processing using the correlation matrix and the eigenvector of the received signal based on the detection information output from the peak detection unit 16a.

[0068] The azimuth angle detection processing unit 16b determines the number of incoming waves based on the number of eigenvalues ​​greater than the thermal noise intensity, and determines the azimuth angle of the object based on the number of incoming waves. For example, the MUSIC method or the ESPRIT method can be used as the arrival direction detection processing. The azimuth angle of the object can be determined using the MUSIC method or the ESPRIT method.

[0069] The azimuth angle detection processing unit 16 outputs azimuth angle detection information indicating the azimuth angle of the object to the collision determination unit 17.

[0070] The collision determination unit 17 is, for example, Fig. 2 is implemented.

[0071] The collision determination unit 17 includes a first evaluation calculation unit 17a, a second evaluation calculation unit 17b, and a determination processing unit 17c.

[0072] If the azimuth angle indicated by the azimuth angle information output from the azimuth angle detection unit 16 agrees with the traveling direction of the vehicle, the collision determination unit 17 determines whether or not an object is located at an altitude at which there is a possibility of collision between the vehicle and the object, based on the distance interval calculated by the distance interval calculation unit 14 and the standard deviation calculated by the altitude standard deviation calculation unit 15.

[0073] The match between the azimuth angle and the vehicle's direction of travel means that a situation occurs where the vehicle and the object intersect on the horizontal plane when the vehicle is moving. On the other hand, a mismatch between the azimuth angle and the vehicle's direction of travel means that a situation where the vehicle and the object intersect on the horizontal plane when the vehicle is moving does not occur.

[0074] The collision determination unit 17 outputs the determination result to the determination result output unit 5.

[0075] In addition, the collision determination unit 17 may cause the determination result to be stored in the storage unit 11.

[0076] The first evaluation calculation unit 17a determines whether or not the azimuth angle indicated by the azimuth angle information output from the azimuth angle detection unit 16 agrees with the traveling direction of the vehicle.

[0077] When the azimuth angle coincides with the traveling direction of the vehicle, the first evaluation calculation unit 17a calculates a first evaluation according to the distance interval calculated by the distance interval calculation unit 14.

[0078] The first evaluation calculation unit 17a outputs the first evaluation to the determination processing unit 17c.

[0079] The second evaluation calculation unit 17b determines whether or not the azimuth angle indicated by the azimuth angle information output from the azimuth angle detection unit 16 agrees with the traveling direction of the vehicle.

[0080] When the azimuth angle coincides with the traveling direction of the vehicle, the second evaluation calculation unit 17b calculates a second evaluation according to the standard deviation calculated by the altitude standard deviation calculation unit 15.

[0081] The second evaluation calculation unit 17b outputs the second evaluation to the determination processing unit 17c.

[0082] The determination processing unit 17c calculates a total index value composed of the sum of the first evaluation calculated by the first evaluation calculation unit 17a and the second evaluation calculated by the second evaluation calculation unit 17b.

[0083] The determination processing unit 17c determines whether or not the object is located at a height at which there is a possibility of collision between the vehicle and the object, based on a comparison result between the total index value and a threshold value.

[0084] That is, when the total index value is greater than a first total threshold value Th1, the determination processing unit 17c determines that the object is located at a position higher than the vehicle and that the object is not at the height where there is a possibility of collision between the vehicle and the object.

[0085] When the total index value is less than a second total threshold value Th2, the determination processing unit 17c determines that the object is located at a position lower than the vehicle and that the object is not at the height where there is a possibility of collision between the vehicle and the object.

[0086] When the total index value is equal to or less than the first total threshold value Th1 and the total index value is equal to or greater than the total threshold value Th2, the determination processing unit 17c determines that an object is located at a height where there is a possibility of collision between the vehicle and the object.

[0087] The determination processing unit 17c outputs the determination result to the determination result output unit 5.

[0088] In addition, the determination processing unit 17c may cause the determination result to be stored in the storage unit 11.

[0089] The first total threshold value Th1 and the second total threshold value Th2 may each be stored in an internal memory of the determination processing unit 17c or provided from outside the signal processing device 4.

[0090] The determination result output unit 5 acquires the determination result output by 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 traveling speed of the vehicle. If the determination result of the signal processing device 4 indicates that an object is present at a height where there is a possibility of collision between the vehicle and the object, the vehicle speed control device controls the traveling speed of the vehicle so that the vehicle does not collide with the object.

[0091] In Fig. 1, it is assumed that the storage unit 11, the map generation unit 13, the distance interval calculation unit 14, the altitude standard deviation calculation unit 15, the azimuth angle detection unit 16 and the collision determination unit 17, which are components of the signal processing device 4, are each implemented by dedicated hardware, as shown in Fig. 2. That is, it is assumed that the signal processing device 4 is realized by the memory circuit 21, the map generation circuit 23, the distance interval calculation circuit 24, the altitude standard deviation calculation circuit 25, the azimuth angle detection circuit 26, and the collision determination circuit 27.

[0092] The memory circuit 21 corresponds, for example, to a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read-only memory (ROM), a flash memory, an erasable programmable read-only memory (EPROM) or an electrically erasable programmable read-only memory (EEPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk or a digital versatile disc (DVD).

[0093] Furthermore, the map generation circuit 23, the distance interval calculation circuit 24, the altitude standard deviation calculation circuit 25, the azimuth angle detection circuit 26, and the collision determination circuit 27 each correspond to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination thereof.

[0094] The components of the signal processing device 4 are not limited to those implemented by dedicated hardware, but the signal processing device 4 may be implemented by software, firmware, or a combination of software and firmware.

[0095] The software or firmware is stored as a program in a computer's memory. The computer refers to hardware that executes a program and corresponds, for example, to a central processing unit (CPU), a central processing device, a processing device, an arithmetic device, a microprocessor, a microcomputer, a processor, or a digital signal processor (DSP).

[0096] Fig. 3 is a hardware configuration diagram of a computer in a case where the signal processing device 4 is implemented by software, firmware, or the like.

[0097] In a case where the signal processing unit 4 is implemented by software, firmware, or the like, the storage unit 11 is configured in the computer's RAM 31. A program that causes a computer to execute processing operations in the map generation unit 13, the distance interval calculation unit 14, the altitude standard deviation calculation unit 15, the azimuth angle detection unit 16, and the collision determination unit 17 is stored in the RAM 31. Subsequently, the computer's processor 32 executes the program stored in the RAM 31.

[0098] In addition, Fig. 2 an example in which each of the components of the signal processing device 4 is implemented by dedicated hardware, and Fig. 3 illustrates an example in which the signal processing device 4 is implemented by software, firmware, or the like. However, this is only an example, and some components of the signal processing device 4 may be implemented by dedicated hardware, while the remaining components may be implemented by software, firmware, or the like.

[0099] The following describes the operation of the radar system, which is located in Fig. 1 is described.

[0100] A transmission unit (not shown) contained within the radar device transmits radio waves toward an object located near the vehicle. The transmission unit that transmits radio waves toward an object may be a device located outside the radar device.

[0101] Any method can be used as the radio wave radiation method, for example a frequency-modulated continuous wave (FMCW) method, a frequency-modulated and intermittent continuous wave (FMICW) method or a pulse Doppler method.

[0102] The antenna 2 of the receiving unit 1 receives a reflected wave from an object present in the surroundings of the vehicle.

[0103] The antenna 2 outputs reception signals r(t) of the reflected waves to the ADC unit 3 at a plurality of times t.

[0104] The ADC unit 3 acquires the reception signals r(t) of the reflected waves at the plurality of times t from the antenna 2.

[0105] The ADC unit 3 converts the received signal r(t) at each time t from an analog signal into a digital signal r D (t) with a preset sampling frequency.

[0106] The ADC unit 3 outputs the digital signal r D (t) to the signal processing device 4 as a reception signal of the reflected wave.

[0107] Fig. 4 is a flowchart showing a signal processing method which is a processing flow of the signal processing device 4.

[0108] The digital signal r output by the ADC unit 3 D (t) is stored in the storage unit 11 and provided to the map generation unit 13.

[0109] The map generation unit 13 acquires the digital signal r D (t) from the receiving unit 1 as the reception signal of the reflected wave at the time t.

[0110] The map generation unit 13 generates the RD map indicating the signal strength level of the received signal by applying a Fourier transform to the digital signal r D(t) in a distance direction and a Doppler velocity direction (step ST1 in Fig. 4).

[0111] Fig. 5 is an explanatory diagram showing an example of an RD map generated by the map generation unit 13.

[0112] In Fig. 5, the horizontal axis represents a Doppler velocity, which is a relative velocity between the vehicle and the object, and the vertical axis represents a relative distance between the vehicle and the object. The RD map is a two-dimensional map that displays the signal strength level SL of the received signal at the relative distance and relative velocity. Fig. 5, the difference in shading represents the difference in signal strength level. Fig. The RD map shown in Figure 5 indicates that there is a single object in the vicinity of the vehicle.

[0113] The relative speed of the Fig. For example, the RD map shown in Figure 5 is divided into V, and the relative distance of the RD map is divided into L. V and L are each an integer of 1 or more.

[0114] The map generation unit 13 outputs the RD map to the distance interval calculation unit 14, the altitude standard deviation calculation unit 15, and the azimuth angle detection unit 16, respectively.

[0115] This describes the positional relationship between the vehicle and the object. Furthermore, the relationship between the direct wave contained in the wave reflected from the object and the multipath wave contained in the reflected wave is described.

[0116] Fig. Figure 6 is an explanatory diagram showing a positional relationship between the vehicle and an upper object, and a wave reflected from the upper object. The upper object is an object located at a higher position than the vehicle and is an object that is not at a height where there is a possibility of collision with the vehicle.

[0117] In the example of Fig. 6, the antenna 2 is located at a position where the height above the ground H R and the upper object is at a position where the height above the ground H T is.

[0118] The example in Fig. Figure 6 shows a situation in which antenna 2 simultaneously receives a direct wave and a multipath wave. However, to simplify the description, only the multipath wave specularly reflected from the ground is shown. The reflection position of the multipath wave on the ground is a position where the ground distance from antenna 2 is equal to R. g,R and is a position where the ground distance from the upper object is R g,T The ground distance between antenna 2 and the upper object is R g = R g,R + R g,T . In the following, the ground clearance is referred to as ground distance.

[0119] The elevation angle of the upper object with respect to the vehicle is θ EL , and the angle of incidence of the multipath wave with respect to the ground and the angle of reflection of the multipath wave with respect to the ground are respectively θ EL,MP .

[0120] The reception signal s of the antenna 2 when the direct wave and the multipath wave are superimposed is expressed by the following expression (1). s=exp(−j2πf0RsC)+KMPexp(−j2πf0RMPC)

[0121] In expression (1), f0 is a center frequency of a radio wave radiated from a transmitting unit not shown included in the radar device, and c is a speed of light.

[0122] R S is the travel time of the direct wave, R MP is the propagation distance of the multipath wave and K MP is the reflection coefficient of the multipath wave.

[0123] The runtime distance R MP of the multipath wave is expressed by the following expression (2). RMP=RR+RT

[0124] In expression (2) R T the travel time from the upper object to the ground, and R R is the propagation time from the ground to antenna 2.

[0125] The ground distance R g between the antenna 2 and the upper object is expressed by the following expression (3) from a geometric relationship. Rg=RscosθEL=Rg,R+Rg,T

[0126] The elevation angle θ EL of the upper object with respect to the vehicle is expressed by the following expression (4), and the angle of incidence θ EL,MP the multipath wave and the reflection angle θ EL,MP of the multipath wave are respectively expressed by the following expression (5). sinθEL=HT−HRRs tanθEL,MP=HRRg,R=HTRg,T

[0127] When the direct wave and the multipath wave interfere with each other due to the superposition of the direct wave and the multipath wave, the following expression (6) holds. RS−RMP=mλ

[0128] In expression (6), m is an integer, and m = 0, ±1, ±2, ..., ±M.

[0129] By transforming the expression (4) the runtime R S the direct wave is expressed by the following expression (7).

[0130] Furthermore, expression (5) can be transformed into the following expression (8), and expression (8) can be transformed into the following expression (9). Therefore, the runtime distance R shown in expression (2) can be MP the multipath wave can be transformed into the following expression (10). RS=HT−HRsinθEL tanθEL,MP=HTRg,T=HR+HTRg sinθEL,MP=sin(arctan(HR+HTRg)) RMP=RR+RT=HT+HRsinθEL,MP

[0131] By replacing expressions (7) and (10) by expression (6), sinθ EL,m in a case where the direct wave and the multipath wave interfere with each other, is expressed by the following expression (11). Therefore, the elevation angle θ EL,mwhen the direct wave and the multipath wave interfere with each other, is expressed by the following expression (12). sinθEL,m=HT−HRHT+HR+mλsinθEL,MP sinθEL,m=arcsin(HT−HRHT+HR+mλsinθEL,MP)=arcsin(HT−HRHT+HR+mλsin(arctan(HR+HTRg))) (12)

[0132] Using the elevation angle θ EL,m In a case where the direct wave and the multipath wave interfere with each other, the propagation time R S,m of the direct wave in a case where the direct wave and the multipath wave interfere with each other is expressed by the following expression (13).

[0133] Furthermore, using the elevation angle θ EL,m the ground distance R g,m between the antenna 2 and the upper object when the direct wave and the multipath wave interfere with each other is expressed by the following expression (14). Rs,m=HT−HRsinθEL,m Rg,m=HT−HRtanθEL,m

[0134] Fig. 7 is an explanatory diagram illustrating the relationship between the ground distance in a case where the object is an upper object, a front object, or a lower object, and the strength of the reception signal s in a case where the direct wave and a multipath wave are superimposed on each other.

[0135] The front object is an object that exists at a height where there is a possibility of collision with the vehicle. The bottom object is an object that is located at a lower position than the vehicle and is an object that is not at a height where there is a possibility of collision with the vehicle.

[0136] In Fig. In Figure 7, a solid line indicates the strength of the received signal s corresponding to the ground distance relative to the upper object, and a dashed line indicates the strength of the received signal s corresponding to the ground distance relative to the front object. A dotted line indicates the strength of the received signal s corresponding to the ground distance relative to the lower object.

[0137] A peak point of the strength of the received signal s is called a peak and a zero point of the strength of the received signal s is called a valley.

[0138] The distance interval between peaks is a distance interval where the direct wave and the multipath wave reinforce each other. The distance interval between valleys is a distance interval where the direct wave and the multipath wave weaken each other. In the distance interval between a point near a peak and a point near the peak, the direct wave and the multipath wave moderately reinforce each other. However, in this application, the distance interval between the peak and the peak is assumed to be a distance interval where the direct wave and the multipath wave reinforce each other.Furthermore, in the distance interval between a point near a valley and a point near the valley, the direct wave and the multipath wave moderately attenuate each other, but in the present application, it is assumed that the distance interval between the valley and the valley is a distance interval in which the direct wave and the multipath wave attenuate each other.

[0139] As in Fig. As shown in Figure 7, the distance interval between the peak and the peak is larger, the higher the altitude at which the object is located. Furthermore, as shown in Fig. As shown in Figure 7, the shorter the ground distance between the antenna 2 and the object, the shorter the distance interval between the peaks.

[0140] The distance interval between the valleys is greater the higher the altitude at which the object is located and the shorter the ground distance between antenna 2 and the object.

[0141] The ground distance R g,m (m = 0, ±1, ±2, ..., ±M) when the direct wave and the multipath wave interfere with each other can be determined based on the increase or decrease in the strength of the received signal s.

[0142] The distance interval ΔR m When the direct wave and the multipath wave interfere with each other, the elevation angle θ EL,m with respect to the m-th ground distance R g,m and the elevation angle θ EL,m+1 with respect to the (m+1)-th ground distance R g,m+1 be calculated as given in the following expression (15). ΔRm=Rs,m+1−Rs,m=(HT,m−HR)(1sinθEL,m+1−1sinθEL,m)

[0143] The distance interval calculation unit 14 acquires the RD map from the map generation unit 13.

[0144] The distance interval calculation unit 14 calculates a reinforcing distance interval ΔR m or a weakening distance interval ΔR m as the distance interval in which the direct wave contained in the reflected wave and the multipath wave contained in the reflected wave interfere with each other based on the RD map (step ST2 in Fig. 4).

[0145] The distance interval calculation unit 14 outputs distance interval information indicating the calculated distance interval ΔR m , to the collision determination unit 17.

[0146] The following describes the calculation processing of the distance interval ΔR m described in more detail by the distance interval calculation unit 14.

[0147] Under the V × L signal strength levels SL specified in the RD map 1,1 to SL V,L the peak detection unit 14a detects a signal strength level SL v,l which is greater than the CFAR-related threshold Th CFAR , as a tip SL peak,m the signal strength level.

[0148] Among the V × L signal strength levels SL 1,1 to SL V,L represents a signal strength level SL v,l which is greater than the threshold Th CFAR represents a signal strength level that refers to a wave reflected from an object in the vicinity of the vehicle.

[0149] The peak detection unit 14a outputs detection information, each of which has a peak SL peak,m relative speed v and one to the tip SL peak,m relative distance I to the elevation angle calculation unit 14b and the travel time calculation unit 14c.

[0150] The elevation angle calculation unit 14b acquires the detection information from the peak detection unit 14a.

[0151] The elevation angle calculation unit 14b calculates an elevation angle θ EL,m (m = 0, ±1, ±2, ..., ±M) when the direct wave and the multipath wave interfere with each other, based on the detection information.

[0152] Specifically, the elevation angle calculation unit 14b calculates the eigenvalue of the correlation matrix by performing the arrival direction detection processing using the correlation matrix and the eigenvector of the reception signal s based on the detection information.

[0153] The elevation angle calculation unit 14b determines the number of incoming waves based on the number of eigenvalues ​​that are larger than the strength of thermal noise and calculates the elevation angle θ EL,m(m = 0, ±1, ±2, ..., ±M) based on the number of waves arriving.

[0154] The elevation angle calculation unit 14b outputs the elevation angle information indicating the elevation angle θ EL,m (m = 0, ±1, ±2, ..., ±M), respectively to the travel time calculation unit 14c and the distance interval calculation processing unit 14d.

[0155] The travel time 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.

[0156] The travel time calculation unit 14c calculates the altitude H T,m of the object by determining the relative distance I with respect to the tip SL peak,m , which is specified by the detection information, by the following expression (16) as the runtime distance R S,m(m = 0, ±1, ±2, ..., ±M) of the direct wave and the elevation angle θ El,m , which is given by the elevation angle information, is replaced by expression (16). The altitude H R , in which the antenna 2 is installed, is stored, for example, in an internal memory of the propagation distance calculation unit 14c. In the multipath environment, the elevation angle θ EL,m contain an error, and therefore the altitude H T,m of the object may contain an error. HT,m=RS,m×sin(θEL,m)+HR

[0157] The travel time calculation unit 14c replaces the altitude H T,m of the object as H T in expression (7), replaces the elevation angle θ EL,m as θ EL in expression (7) and replaces the altitude H R, in which the antenna 2 is installed, in expression (7), thereby calculating a plurality of propagation distances of the direct wave when the direct wave and the multipath wave interfere with each other. The propagation distance calculation unit 14c outputs the propagation distance information indicating the propagation distance R S,m , to the distance interval calculation processing unit 14d.

[0158] The distance interval calculation unit 14d acquires the elevation angle information from the elevation angle calculation unit 14b, and acquires the travel time distance information from the travel time distance calculation unit 14c.

[0159] The distance interval calculation processing unit 14d specifies the travel time R S,m , which refers to the m-th ground distance R g,m refers, and the runtime distance R S,m+1 , which refers to the (m+1)-th ground distance R g,m+1refers to the multitude of runtime distances R S,0 to R S,m , which are specified by the runtime distance information.

[0160] The distance interval calculation processing unit 14d calculates a distance interval ΔR ,m , when the direct wave and the multipath wave interfere with each other by changing the m-th propagation path R S,m and the (m+1)-th runtime R S,m+1 replaced by expression (15).

[0161] The distance interval calculation processing unit 14 outputs distance interval information indicating the distance interval ΔR m , to the collision determination unit 17.

[0162] Here, the distance interval calculation processing unit 14d calculates the distance interval ΔR m from the m-th runtime R S,m and the (m+1)-th runtime R S,m+1. However, this is only an example, and the distance interval calculation processing unit 14d may calculate the distance interval ΔR m from the elevation angle θ EL,m with respect to the m-th ground distance R g,m and the elevation angle θ EL,m+1 with respect to the (m+1)-th ground distance R g,m+1 calculate.

[0163] That is, the distance interval calculation processing unit 14d specifies the m-th elevation angle θ EL,m and the (m+1)-th elevation angle θ EL,m+1 from the multitude of elevation angles θ EL,1 to θ EL,M , which are specified by the elevation angle information.

[0164] The distance interval calculation processing unit 14d calculates the distance interval ΔR m , when the direct wave and the multipath wave interfere with each other by changing the m-th elevation angle θ EL,m , the (m+1)-th elevation angle θ EL,m+1, the altitude H T,m and the altitude H R replaced by expression (15).

[0165] The altitude standard deviation calculation unit 15 acquires the RD map from the map generation unit 13.

[0166] The altitude standard deviation calculation unit 15 calculates the standard deviation H std the altitude at which the object is located based on the RD map (step ST3 in Fig. 4).

[0167] The altitude standard deviation calculation unit 15 outputs the calculation result of the standard deviation H std to the collision determination unit 17.

[0168] The following describes the calculation processing of the standard deviation H std described in more detail by the altitude standard deviation calculation unit 15.

[0169] The peak detection unit 15a detects the peak SL peak,mthe signal strength level based on the RD map generated by the map generation unit 13, similar to the peak detection unit 14a.

[0170] The peak detection unit 15a outputs detection information each indicating the relative distance with respect to the detected peak SL peak,m and the relative speed with respect to the detected peak SL peak,m to the altitude calculation unit 15b.

[0171] The altitude calculation unit 15b acquires detection information from the peak detection unit 15a.

[0172] The altitude calculation unit 15b calculates the travel time R S,m (m = 0, ±1, ±2, ..., ±M) of the direct wave when the direct wave and the multipath wave interfere with each other, based on the detection information, similarly to the delay time calculation unit 14c.

[0173] Furthermore, the altitude calculation unit 15b calculates the elevation angle θ EL,m (m = 0, ±1, ±2, ..., ±M) when the direct wave and the multipath wave interfere with each other, based on the detection information, similar to the elevation angle calculation unit 14b.

[0174] The altitude calculation unit 15b calculates the altitude H T,m (m = 0, ±1, ±2, ..., ±M) at a variety of times by determining the runtime R S,m , the elevation angle θ EL,m , and the altitude H R replaced by the expression (16). The altitude H R is stored, for example, in an internal memory of the altitude calculation unit 15b.

[0175] The altitude calculation unit 15b outputs the calculation result of the altitude H T,m to the standard deviation calculation processing unit 15c.

[0176] The standard deviation calculation processing unit 15c acquires the calculation result of the altitude H T,m from the altitude calculation unit 15b.

[0177] The standard deviation calculation processing unit 15c calculates the standard deviation H std the altitude from the altitudes H T,1 to H T,M at the plurality of times expressed by the following expression (17).

[0178] The standard deviation calculation processing unit 15c outputs the calculation result of the standard deviation H std to the collision determination unit 17. Hstd=std(HT,1, HT,2, ⋯, HT,M)

[0179] In expression (17), std() is a function for calculating the standard deviation of the altitudes H T,1 to H T,M in brackets.

[0180] The azimuth angle acquisition unit 16 acquires the RD map from the map generation unit 13.

[0181] The azimuth angle detecting unit 16 detects an azimuth angle of an object with respect to the vehicle based on the RD map.

[0182] The azimuth angle detection unit 16 outputs azimuth angle detection information indicating the azimuth angle of the object to the collision determination unit 17.

[0183] The azimuth angle detection processing by the azimuth angle determination unit 16 will be described in more detail below.

[0184] The peak detection unit 16a detects the peak SL peak,m the signal strength level based on the RD map generated by the map generation unit 13, similar to the peak detection unit 14a.

[0185] The peak detection unit 16a outputs detection information each indicating the relative distance with respect to the detected peak SL peak,m and the relative speed with respect to the detected peak SL peak,mto the azimuth angle detection processing unit 16b.

[0186] The azimuth angle detection calculation unit 16b acquires detection information from the peak detection unit 16a.

[0187] The azimuth angle detection processing unit 16b calculates a plurality of elevation angles of the object with respect to the vehicle when the direct wave and the multipath wave interfere with each other, based on the detection information.

[0188] Specifically, the azimuth angle detection processing unit 16b calculates the eigenvalue of the correlation matrix by performing the arrival direction detection processing using the correlation matrix and the eigenvector of the received signal s based on the detection information output from the peak detection unit 16a.

[0189] The azimuth angle detection processing unit 16b determines the number of incoming waves based on the number of eigenvalues ​​greater than the strength of the thermal noise, and determines the azimuth angle of the object based on the number of incoming waves.

[0190] The azimuth angle detection processing unit 16 outputs the azimuth angle detection information indicating the azimuth angle of the object to the collision determination unit 17.

[0191] The collision determination unit 17 acquires the distance interval ΔR m from the distance interval calculation unit 14, acquires the standard deviation H std the altitude from the altitude standard deviation calculation unit 15 and acquires the azimuth angle information from the azimuth angle acquisition unit 16.

[0192] If the azimuth angle indicated by the azimuth angle information coincides with the traveling direction of the vehicle, the collision determination unit 17 determines whether or not the object is at a height at which there is a possibility of collision between the vehicle and the object, based on the distance interval ΔR m and the standard deviation H std the altitude (step ST4 in Fig. 4).

[0193] The collision determination unit 17 outputs the determination result to the determination result output unit 5.

[0194] The determination processing by the collision determination unit 17 is described in more detail below.

[0195] The first judgment calculation unit 17a determines whether or not the azimuth angle indicated by the azimuth angle information agrees with the traveling direction of the vehicle.

[0196] When the azimuth angle coincides with the traveling direction of the vehicle, the first evaluation calculation unit 17a sets a first threshold value Th UP,r , which indicates the boundary between the upper object and the front object, and a second threshold Th DW,r , which specifies the boundary between the front object and the bottom object for any ground distance r. r is an integer equal to or greater than 1.

[0197] Next, threshold setting processing by the first evaluation calculation unit 17a will be described in more detail.

[0198] As in Fig. 7, the distance interval between the peaks, which is the distance interval ΔR m is, when the direct wave and the multipath wave reinforce each other, larger with increasing altitude at which the object is located. Furthermore, as in Fig. As shown in Figure 7, the shorter the ground distance between the antenna 2 and the object, the shorter the distance interval between the peaks.

[0199] Therefore, the first threshold Th UP,r and the second threshold Th DW,r for the short ground distance r is set to a small value r. On the other hand, the first threshold value Th UP,r and the second threshold Th DW,r for the long ground distance r each set to a large value r.

[0200] For example, an internal memory of the first-evaluation calculation unit 17a stores a distance interval ΔR FRO,r for any ground distance r, if an object present in the surroundings of the vehicle is the front object, as expressed in the following expression (18). For example, the altitude H T,FRO of the front object lower than the altitude H Celthe ceiling of the vehicle. For example, the altitude H T,FRO of the front object higher than a minimum ground level H FLO of the vehicle. H applies FLO < H Cel . ΔRFRO,r=Rs,m+1−Rs,m=(HT,FRO−HR)(1sin θEL,m+1−1sin θEL,m)

[0201] The first evaluation calculation unit 17a sets the first threshold Th UP,r , which is the boundary between the upper object and the front object, for each ground distance r, using the distance interval ΔR FrO,r for each ground distance r, as expressed in the following expression (19).

[0202] Furthermore, the first evaluation calculation unit 17a sets the second threshold value Th DW,r , which is the boundary between the front object and the bottom object, for each ground distance r, using the distance interval ΔR FrO,rfor each ground distance r, as expressed in the following expression (20). ThUP,r=P1×ΔRFRO,r ThDW,r=P2×ΔRFRO,r

[0203] In expression (19), P1 is a coefficient greater than 1 and a coefficient that exceeds the first threshold Th UP,r larger than the distance interval ΔR FrO,r with respect to the front object. The altitude corresponding to the distance interval ΔR FRO,r is preferably higher than the altitude H Cel the ceiling of the vehicle and as close as possible to the altitude H Cel . Thus, the first threshold value Th UP,r set to a distance interval corresponding to the altitude H T1 which is slightly higher than the altitude H Cel , such as in Fig. 8 shown. Fig. Fig. 8 is an explanatory diagram showing a setting example of the first threshold value Th UP,r shows.

[0204] In expression (20), P2 is a coefficient less than 1 and a coefficient that exceeds the second threshold Th Dw,r smaller than the distance interval ΔR FrO,r with respect to the front object. The altitude corresponding to the distance interval ΔR FRO,r is preferably lower than the minimum ground level H FLO of the vehicle and as close as possible to the minimum ground height H FLO . Thus, the second threshold Th Dw,r set to a distance interval corresponding to the altitude H T1 ' which is slightly lower than the minimum ground level H FLO , such as in Fig. 9 shown. Fig. Fig. 9 is an explanatory diagram showing an example of setting the second threshold value Th DW,r shows.

[0205] The first evaluation calculation unit 17a acquires the distance interval ΔR m(m = 0, ±1, ±2, ..., ±M) from the distance interval calculation unit 14.

[0206] The first evaluation calculation unit 17a specifies a distance interval ΔR r , which corresponds to the ground distance r, under the distance intervals ΔR0 to ΔR M For example, if the peak with the shorter ground distance among the two peaks covering the distance interval ΔR m of m = 5, belongs to the ground distance “3”, the first evaluation calculation unit 17a sets the distance interval ΔR m from m = 5 to the distance interval ΔR r of r = 3.

[0207] After setting the first threshold Th UP,r and the second threshold Th DW,r the first evaluation calculation unit 17a compares the distance interval ΔR r with the first threshold Th UP,r and compares the distance interval ΔR r with the second threshold ThDw,r for each ground distance r.

[0208] If the distance interval ΔR r is greater than the first threshold Th UP,r , the first evaluation calculation unit 17a sets the value of the first evaluation to a first value.

[0209] If the distance interval ΔR r is equal to or less than the first threshold Th UP,r and the distance interval ΔR r is equal to or greater than the second threshold TH DW,r , the first evaluation calculation unit 17a sets the value of the first evaluation to a second value.

[0210] If the distance interval ΔR r is smaller than the second threshold Th DW,r , the first evaluation calculation unit 17a sets the value of the first evaluation to a third value. The first value > the second value > the third value applies.

[0211] The first evaluation calculation unit 17a outputs the first evaluation to the determination processing unit 17c.

[0212] Here, the first evaluation calculation unit 17a sets the first evaluation according to the comparison result between the distance interval ΔR r and the first threshold Th UP,r and the second threshold Th DW,r However, this is only an example, and the first evaluation calculation unit 17a may obtain a larger first evaluation if the distance interval ΔR r is larger by increasing the distance interval ΔR r replaced by a multifunctional expression for calculating the first rating.

[0213] The second evaluation calculation unit 17b determines whether or not the azimuth angle indicated by the azimuth angle information agrees with the traveling direction of the vehicle.

[0214] When the azimuth angle matches the traveling direction of the vehicle, the second evaluation calculation unit 17b sets a third threshold value Th UP',r , which indicates the boundary between the upper object and the front object, and a fourth threshold Th DW',r , which indicates the boundary between the front object and the bottom object, for each ground distance r.

[0215] Next, threshold setting processing by the second evaluation calculation unit 17b will be described in detail.

[0216] Fig. 10 is an explanatory diagram showing an example of angle measurement values ​​of elevation angles of an upper object, a front object, and a lower object, which are objects.

[0217] In Fig. 10, the horizontal axis represents the relative distance between the vehicle and the object, and the vertical axis represents the elevation angle of the object.

[0218] △ is a measured angle value of the elevation angle of the upper object, □ is a measured angle value of the elevation angle of the front object, and ◯ is a measured angle value of the elevation angle of the lower object.

[0219] As from Fig. As can be seen from Figure 10, as the altitude of the object increases, the angle measurement accuracy of the elevation angle is more likely to deteriorate due to the influence of the multipath wave.

[0220] Fig. 11 is an explanatory diagram showing an example of standard deviations of heights of an upper object, a front object, and a lower object, which are objects.

[0221] In Fig. 11, the horizontal axis represents the relative distance between the vehicle and the object, and the vertical axis represents the standard deviation of the object's elevation.

[0222] △ is a standard deviation of the elevation of the upper object, □ is a standard deviation of the elevation of the front object, and ◯ is a standard deviation of the elevation of the lower object.

[0223] As from Fig. As can be seen in Figure 11, with increasing altitude of the object, the standard deviation of the object's altitude is more likely to deteriorate due to the influence of multipath waves, similar to the measured angular value of the elevation angle. Thus, the standard deviation of the altitude of the upper object is larger than the standard deviation of the altitude of the front object. Furthermore, the standard deviation of the altitude of the front object is larger than the standard deviation of the altitude of the lower object.

[0224] In the example of Fig. 11, the third threshold value Th UP',rbetween the standard deviation of the elevation of the upper object and the standard deviation of the elevation of the front object for each ground distance r. Furthermore, the fourth threshold Th DW',r between the standard deviation of the elevation of the front object and the standard deviation of the elevation of the bottom object for each ground distance r.

[0225] Furthermore, the third threshold Th UP',r and the fourth threshold Th DW',r preferably as close as possible to the standard deviation of the elevation of the front object.

[0226] For example, an internal memory of the second evaluation calculation unit 17b stores a standard deviation H FROstd,r the altitude for each ground distance r when an object present in the surroundings of the vehicle is the front object.

[0227] The second evaluation calculation unit 17b sets the third threshold ThUP',r , which indicates the boundary between the upper object and the front object, for each ground distance r using the standard deviation H FROstd,r the altitude for each ground distance r, as expressed in the following expression (21).

[0228] Further, the second evaluation calculation unit 17b sets the fourth threshold value Th DW',r , which indicates the boundary between the front object and the bottom object, for each ground distance r using the standard deviation H FROstd,r the altitude for each ground distance r, as expressed in the following expression (22). ThUP',r=P3×HFROstd,r ThDW',r=P4×HFROstd,r

[0229] In expression (21), P3 is a coefficient greater than 1 and a coefficient that exceeds the third threshold Th UP',r greater than the standard deviation H FROstd,r the altitude relative to the front object. The third threshold Th UP',ris preferably higher than the altitude H Cel the ceiling of the vehicle and as close as possible to the altitude H Cel .

[0230] In expression (22), P4 is a coefficient less than 1 and a coefficient that exceeds the fourth threshold Th DW',r smaller than the standard deviation H FROstd,r the altitude relative to the front object. The fourth threshold Th DW',r is preferably lower than the minimum ground level H FLO of the vehicle and as close as possible to the minimum ground height H FLO .

[0231] The second evaluation calculation unit 17b acquires the calculation result of the standard deviation H std the altitude from the altitude standard deviation calculation unit 15.

[0232] The second evaluation calculation unit 17b specifies the ground distance according to the standard deviation H std the altitude and sets the standard deviation Hstd than the standard deviation H FRostd,r the ground distance r.

[0233] For example, if the ground distance of the standard deviation H std the altitude of the ground distance of r = 7, the standard deviation H std than the standard deviation H FROstd,7 If the ground distance is equal to the standard deviation H std the altitude corresponds to the ground distance of r = 8, the standard deviation H std than the standard deviation H FROstd,8 set.

[0234] After the third threshold Th UP',r and the fourth threshold Th DW',r have been determined, the Second Assessment Calculation Unit 17b compares the standard deviation H FROstd,r the altitude and the third threshold Th UP',r and compares the standard deviation H FROstd,r the altitude and the fourth threshold Th DW',r for each ground distance r.

[0235] If the standard deviation H FROstd,r the altitude is greater than the third threshold Th UP',r , the second evaluation calculation unit 17b sets the value of the second evaluation to a fourth value.

[0236] The second evaluation calculation unit 17b sets the value of the second evaluation to a fifth value when the standard deviation H FROstd,r the altitude is equal to or less than the third threshold Th UP',r and the standard deviation H FROstd,r the altitude is equal to or greater than the fourth threshold Th DW',r .

[0237] If the standard deviation H FROstd,r the altitude is less than the fourth threshold Th DW',r , the second evaluation calculation unit 17b sets the value of the second evaluation to a sixth value. The fourth value > the fifth value > the sixth value applies.

[0238] The second evaluation calculation unit 17b outputs the second evaluation to the determination processing unit 17c.

[0239] Here, the second evaluation calculation unit 17b sets the second evaluation according to the comparison result between the standard deviation H FROstd,r the altitude and the third threshold Th UP',r and the fourth threshold Th DW',r However, this is only an example, and the second rating calculation unit 17b may calculate a larger second rating with increasing size of the standard rating H FROstd,r obtained by calculating the standard deviation H FROstd,r the altitude is replaced by the multifunctional expression for calculating the second rating.

[0240] The determination processing unit 17c acquires the first evaluation from the first evaluation calculation unit 17a and acquires the second evaluation from the second evaluation calculation unit 17b.

[0241] The determination processing unit 17c calculates a total index value Ind which is the sum of the first evaluation and the second evaluation.

[0242] Here, the determination processing unit 17c calculates the total index value Ind by adding the first score and the second score. However, this is only an example, and the determination processing unit 17c may calculate the total index value Ind by weighting and adding the first score and the second score.

[0243] Fig. 13 is a flowchart showing determination processing of the determination processing unit 17c.

[0244] The determination processing unit 17c compares the total index value Ind with the first total threshold value Th1.

[0245] If the total index value Ind is greater than the first total threshold value Th1 (step ST21 in Fig. 13: YES), the determination processing unit 17c determines that an object present in the surroundings of the vehicle is an upper object (step ST22 in Fig. 13).

[0246] That is, the determination processing unit 17c determines that there is no object at a height where there is a possibility of collision between the vehicle and the object.

[0247] If the total index value Ind is equal to or less than the first total threshold value Th1 (step ST21 in Fig. 13: NO), the determination processing unit 17c compares the total index value Ind with the second total threshold value Th2.

[0248] If the total index value Ind is smaller than the second total threshold value Th2 (step ST23 in Fig. 13: YES), the determination processing unit 17c determines that an object present in the surroundings of the vehicle is a lower object (step ST24 in Fig. 13).

[0249] That is, the determination processing unit 17c determines that there is no object at a height where there is a possibility of collision between the vehicle and the object.

[0250] If the total index value Ind is equal to or greater than the second total threshold value Th2 (step ST23 in Fig. 13: NO), the determination processing unit 17c determines that an object present in the surroundings of the vehicle is a front object (step ST25 in Fig. 13).

[0251] That is, the determination processing unit 17c determines that there is an object at a height at which there is a possibility of collision between the vehicle and the object.

[0252] The determination processing unit 17c outputs the determination result to the determination result output unit 5.

[0253] The determination result output unit 5 acquires the determination result from the collision determination unit 17 and outputs the determination result to, for example, an unillustrated vehicle speed control device.

[0254] If the determination result of the collision determination unit 17 indicates that the object is present at a height where there is a possibility of collision between the vehicle and the object, the vehicle speed control device controls the traveling speed of the vehicle, for example, so that the vehicle does not collide with the object.

[0255] The Fig. The signal processing device 4 shown in Fig. 1 comprises both the distance interval calculation unit 14 and the altitude standard deviation calculation unit 15, and the collision determination unit 17 determines, on the basis of the distance interval ΔR calculated by the distance interval calculation unit 14 m and the standard deviation H calculated by the altitude standard deviation calculation unit 15 std whether or not an object is present at a height where there is a possibility of collision between the vehicle and the object. However, this is only an example, and it is also possible that the signal processing device 4 does not include the distance interval calculation unit 14, and the collision determination unit 17 based on the standard deviation H calculated by the altitude standard deviation calculation unit 15 stddetermines whether or not an object is at a height where there is a possibility of collision between the vehicle and the object.

[0256] If in this case the standard deviation H FROstd,r the altitude is greater than the third threshold Th UP',r , the collision determination unit 17 determines that the object in the vicinity of the vehicle is an upper object. That is, the collision determination unit 17 determines that there is no object at a height where there is a possibility of collision between the vehicle and the object.

[0257] If the standard deviation H FROstd,r the altitude is less than the fourth threshold Th DW',r, the collision determination unit 17 determines that the object in the vicinity of the vehicle is a lower object. That is, the collision determination unit 17 determines that there is no object at a height where there is a possibility of collision between the vehicle and the object.

[0258] If the standard deviation H FROstd,r the altitude is equal to or less than the third threshold Th UP',r and the standard deviation H FROstd,r the altitude is equal to or greater than the fourth threshold Th DW',r , the collision determination unit 17 determines that the object present in the vicinity of the vehicle is a front object. That is, the collision determination unit 17c determines that there is an object at a height where there is a possibility of collision between the vehicle and the object.

[0259] In a case where the signal processing device 4 does not include the distance interval calculation unit 14, the configuration can be simplified more than in a case where the signal processing device 4 includes both the distance interval calculation unit 14 and the altitude standard deviation calculation unit 15.

[0260] In the first embodiment explained above, the signal processing device 4 is configured to include the map generation unit (13) that acquires a reception signal of the reflected wave from the reception unit (1) that receives the reflected wave from the object located in the vicinity of a mobile object and generates the range Doppler map indicating a signal strength level of the reception signal, and the altitude standard deviation calculation unit (15) that calculates the standard deviation of the altitude at which the object is located based on the range Doppler map generated by the map generation unit (13).Furthermore, the signal processing device 4 includes the collision determination unit 17 for determining whether or not the object is located at an altitude where there is a possibility of collision between the mobile object and the object, based on the standard deviation calculated by the altitude standard deviation calculation unit 15. Therefore, the signal processing device 4 can determine whether or not an object is located at an altitude where there is a possibility of collision between the mobile object and the object, based on the reflected wave reception signal received by only one reception unit in the multipath environment.

[0261] Furthermore, in the first embodiment, the signal processing device 4 is configured to include the distance interval calculation unit 14 that 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 distance Doppler map generated by the map generation unit 13. Furthermore, the collision determination unit 17 in the signal processing device 4 determines whether or not an object is located at an altitude where there is a possibility of collision between the mobile object and the object, based on the distance interval calculated by the distance interval calculation unit 14 and the standard deviation calculated by the altitude standard deviation calculation unit 15.Therefore, the signal processing device 4 can improve the accuracy of determination more than in the case where it is determined only on the basis of the standard deviation whether or not an object is located at a height at which there is a possibility of collision between the mobile object and the object.

[0262] In the signal processing device 4, shown in Fig. 1, the second evaluation calculation unit 17b of the collision determination unit 17 sets the third threshold value Th UP',r and the fourth threshold Th DW',r using the standard deviation H FROstd,r the altitude for each ground distance r. However, this is only an example, and the second evaluation calculation unit 17b may set the third threshold value Th UP',r and the fourth threshold Th DW',r using the standard deviation of the received signal strength, as in Fig. 12 shown.

[0263] Fig. 12 is an explanatory diagram showing an example of standard deviations of a received signal strength of respective reflected waves of an upper object, a front object, and a lower object, which are objects.

[0264] In Fig. 12, the horizontal axis represents the relative distance between the vehicle and the object, and the vertical axis represents the standard deviation of the received signal strength.

[0265] As from Fig. As can be seen from Figure 12, as the altitude of the object increases, the standard deviation of the received signal strength is more likely to deteriorate due to the influence of multipath waves, similar to the standard deviation of the altitude. Therefore, the standard deviation of the received signal strength with respect to the upper object is larger than the standard deviation of the received signal strength with respect to the front object. Furthermore, the standard deviation of the received signal strength with respect to the front object is larger than the standard deviation of the received signal strength with respect to the bottom object.

[0266] In the example of Fig. 12, for each ground distance r a temporary threshold value Th UP2,r between the standard deviation of the received signal strength with respect to the upper object and the standard deviation of the received signal strength with respect to the front object. Furthermore, a temporary threshold Th is set for each ground distance r.DW,r2 between the standard deviation of the received signal strength with respect to the front object and the standard deviation of the received signal strength with respect to the bottom object.

[0267] For example, the second evaluation calculation unit 17b calculates the third threshold value Th UP',r by setting the temporary threshold Th UP2,r is replaced by the following expression (23).

[0268] Further, the second evaluation calculation unit 17b calculates, for example, the fourth threshold value Th DW',r by setting the temporary threshold Th DW2,r is replaced by the following expression (24). ThUP',r=P5×ThUP2,r+P6 ThDW',r=P7×ThDW2,r+P8

[0269] In expressions (23) to (24), each of the parameters P5, P6, P7 and P8 is a parameter for temporary threshold adjustment. Second embodiment

[0270] In a second embodiment, the signal processing device 4 is described for a case where several objects with different azimuth angles with respect to the vehicle are present.

[0271] Fig. 14 is a configuration diagram illustrating a radar device according to the second embodiment.

[0272] Fig. 15 is a hardware configuration diagram illustrating hardware of a signal processing device 4 according to the second embodiment.

[0273] The Fig. The radar device shown in Figure 14 comprises the receiving unit 1, the signal processing unit 4 and the determination result output unit 5.

[0274] The signal processing unit 12 includes the map generation unit 13, the distance interval calculation unit 14, the altitude standard deviation calculation unit 15, the azimuth angle detection unit 16, and a collision determination unit 18.

[0275] The collision determination unit 18 is, for example, Fig. 15 illustrated collision determination circuit 28 is implemented.

[0276] The collision determination unit 18 includes a first evaluation calculation unit 18a, a second evaluation calculation unit 18b, and a determination processing unit 18c.

[0277] The collision determination unit 18 determines each of the azimuth angles of the plurality of objects based on the azimuth angle information output from the azimuth angle detection unit 16.

[0278] The collision determination unit 18 specifies an object whose azimuth angle coincides with the traveling direction of the vehicle from the plurality of objects.

[0279] For the specified object, the collision determination unit 18 determines whether or not there is an object at an altitude at which there is a possibility of collision between the mobile object and the object, based on the distance interval calculated by the distance interval calculation unit 14 and the standard deviation calculated by the altitude standard deviation calculation unit 15.

[0280] The collision determination unit 18 does not perform determination processing on an object whose azimuth angle does not match the traveling direction of the vehicle.

[0281] The collision determination unit 18 outputs the determination result to the determination result output unit 5.

[0282] The first evaluation calculation unit 18a specifies each of the azimuth angles of the plurality of objects based on the azimuth angle information output from the azimuth angle detection unit 16, and specifies an object whose azimuth angle agrees with the traveling direction of the vehicle from the plurality of objects.

[0283] The first evaluation calculation unit 18a calculates the first evaluation for the specified object according to the distance interval calculated by the distance interval calculation unit 14.

[0284] The first evaluation calculation unit 18a outputs the first evaluation to the determination processing unit 18c.

[0285] The second evaluation calculation unit 18b specifies each of the azimuth angles of the plurality of objects based on the azimuth angle information output from the azimuth angle detection unit 16, and specifies an object whose azimuth angle agrees with the traveling direction of the vehicle from the plurality of objects.

[0286] The second evaluation calculation unit 18b calculates the second evaluation for the specified object according to the standard deviation calculated by the altitude standard deviation calculation unit 15.

[0287] The second evaluation calculation unit 18b outputs the second evaluation to the determination processing unit 18c.

[0288] Similar to the Fig. 1, the determination processing unit 18c calculates a total index value composed of the sum of the first evaluation calculated by the first evaluation calculation unit 18a and the second evaluation calculated by the second evaluation calculation unit 18b.

[0289] The determination processing unit 18c determines whether or not the object is located at a height at which there is a possibility of collision between the vehicle and the object, based on the comparison result between the total index value and the threshold value.

[0290] In Fig. 14, it is assumed that the storage unit 11, the map generation unit 13, the distance interval calculation unit 14, the altitude standard deviation calculation unit 15, the azimuth angle detection unit 16 and the collision determination unit 18, which are components of the signal processing device 4, are each implemented by dedicated hardware, as shown in Fig. 15. That is, it is assumed that the signal processing device 4 is realized by the memory circuit 21, the map generation circuit 23, the distance interval calculation circuit 24, the altitude standard deviation calculation circuit 25, the azimuth angle detection circuit 26, and the collision determination circuit 28.

[0291] Furthermore, the map generation circuit 23, the distance interval calculation circuit 24, the altitude standard deviation calculation circuit 25, the azimuth angle detection circuit 26, and the collision determination circuit 28 each 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.

[0292] The components of the signal processing device 4 are not limited to those implemented by dedicated hardware, but the signal processing device 4 may be implemented by software, firmware, or a combination of software and firmware.

[0293] In a case where the signal processing unit 4 is implemented by software, firmware or the like, the storage unit 11 is in the main memory 31 of the computer shown in Fig. 3, is configured. A program that causes a computer to execute processing operations in the map generation unit 13, the distance interval calculation unit 14, the altitude standard deviation calculation unit 15, the azimuth angle detection unit 16, and the collision determination unit 18 are stored in the working memory 31. Then, the Fig. 3, the processor 32 executes the program stored in the main memory 31.

[0294] In addition, Fig. 15 an example in which each of the components of the signal processing device 4 is implemented by dedicated hardware, and Fig. 3 illustrates an example in which the signal processing device 4 is implemented by software, firmware, or the like. However, this is only an example, and some components of the signal processing device 4 may be implemented by dedicated hardware, while the remaining components may be implemented by software, firmware, or the like.

[0295] Fig. 16 is an explanatory diagram showing a plurality of objects having different azimuth angles with respect to a vehicle.

[0296] In the example of Fig. 16, there are two objects, and one object is an upper object whose azimuth angle coincides with the direction of travel of the vehicle. The travel time of the direct wave from the upper object is R S , and the travel time of the multipath wave from the upper object is R MP .

[0297] The other object is an object whose azimuth angle does not match the vehicle's direction of travel. The distance between the vehicle and the other object is R AZ .

[0298] In the example of Fig. 16, the reflected wave received by the antenna 2 includes a direct wave from the upper object, a multipath wave from the upper object, and a reflected wave from the other object.

[0299] In this case, a reception signal s' of the antenna 2 is expressed by the following expression (25). s'=exp(−j2πf0Rsc)+KMPexp(−j2πf0RMPc)+KAZexp(−j2πf0RAZc)

[0300] In expression (25) K AZ for a reflection coefficient.

[0301] When the direct wave from the upper object and the multipath wave from the upper object intersect to cause the direct wave and the multipath wave to interfere with each other, the following expression (26) applies. In a case where the multipath wave from the upper object and the reflected wave from the other object interfere with each other due to the superposition of the multipath wave from the upper object and the reflected wave from the other object, the following expression (27) applies.

[0302] Furthermore, in the case where the direct wave of the upper object and the reflected wave of the other object interfere with each other, the following expression (28) also holds. Rs−RMP=m1λ(m1=0,±1, ±2, ⋯) RMP−RAZ=m2λ(m2=0, ±1, ±2, ⋯) Rs−RAZ=m3λ(m3=0, ±1, ±2, ⋯)

[0303] The distance interval ΔR m1When the direct wave from the upper object and the multipath wave from the lower object interfere with each other, the elevation angle θ EL,m1 with respect to the m1-th ground distance R g,m1 and the elevation angle θ EL,m1+1 with respect to the (m1+1)-th ground distance R g,m1+1 be calculated as given in the following expression (29). ΔRm1=Rs,m1+1−Rs,m1=(HT,m1−HR)(1sin θEL,m1+1−1sin θEL,m1)

[0304] The distance interval ΔR m3 , in which the direct wave from the upper object and the multipath wave from the lower object interfere with each other, can be determined from the elevation angle θ EL,m3 in terms of the m3-th soil removal R g,m3 and the elevation angle θ EL,m3+1 in relation to the (m3+1)-th soil removal R g,m3+1 be calculated as given in the following expression (30). ΔRm3=Rs,m3+1−Rs,m3=(HT,m3−HR)(1sin θEL,m3+1−1sin θEL,m3)

[0305] The following describes the operation of the radar system, which is located in Fig. 14. The radar device, with the exception of the collision determination unit 18, is of the type shown in Fig. 1. Therefore, only the operation or functioning of the collision determination unit 18 is described here.

[0306] The first evaluation calculation unit 18a of the collision determination unit 18 determines the azimuth angle from the azimuth angle detection unit 16.

[0307] The first evaluation calculation unit 18a specifies each of the azimuth angles of the plurality of objects based on the azimuth angle information.

[0308] The first-judgment calculation unit 18a determines whether or not the azimuth angle of each object coincides with the traveling direction of the vehicle.

[0309] When there is an object among the plurality of objects whose azimuth angle coincides with the traveling direction of the vehicle, the first evaluation calculation unit 18a sets the first threshold value Th UP,r and the second threshold Th Dw,r for the object whose azimuth angle coincides with the direction of travel of the vehicle. The procedure for setting the first threshold values ​​Th UP,r and the like by the first evaluation calculation unit 18a is similar to the method of setting the first threshold values ​​Th UP,r and the like by the Fig. 1 shown initial assessment calculation unit 17a.

[0310] The first evaluation calculation unit 18a calculates a first evaluation for an object whose azimuth angle coincides with the traveling direction of the vehicle, according to a method similar to that described in Fig. 1 is similar to the initial assessment calculation unit 17a.

[0311] The first evaluation calculation unit 18a does not calculate the first evaluation for an object whose azimuth angle does not coincide with the traveling direction of the vehicle.

[0312] In the example of Fig. 16, the first evaluation calculation unit 18a calculates the first evaluation for the upper object and does not calculate the first evaluation for another object.

[0313] The second evaluation calculation unit 18b acquires the azimuth angle information from the azimuth angle acquisition unit 16.

[0314] Similar to the first-evaluation calculation unit 18a, the second-evaluation calculation unit 18b specifies each of the azimuth angles of the plurality of objects based on the azimuth angle information and determines whether or not the azimuth angle of each object agrees with the traveling direction of the vehicle.

[0315] When there is an object among the plurality of objects whose azimuth angle coincides with the traveling direction of the vehicle, the second evaluation calculation unit 18b sets the third threshold value Th UP',r and the fourth threshold Th Dw,r for the object whose azimuth angle coincides with the direction of travel of the vehicle. The method of setting the third threshold Th UP',r and the like by the second evaluation calculation unit 18b is similar to the method of setting the third threshold Th UP',r and the like by the Fig. 1 shown second-value calculation unit 17b.

[0316] The second evaluation calculation unit 18b calculates a second evaluation for an object whose azimuth angle coincides with the traveling direction of the vehicle, according to a method similar to that described in Fig. 1 is similar to the initial assessment calculation unit 17a.

[0317] The second evaluation calculation unit 18b does not calculate the second evaluation for an object whose azimuth angle does not coincide with the traveling direction of the vehicle.

[0318] In the example of Fig. 16, the second evaluation calculation unit 18b calculates the second evaluation for the upper object and does not calculate the second evaluation for another object.

[0319] Similar to the Fig. 1, the determination processing unit 18c calculates a total index value composed of the sum of the first evaluation calculated by the first evaluation calculation unit 18a and the second evaluation calculated by the second evaluation calculation unit 18b.

[0320] Similar to the Fig. 1, the determination processing unit 18c determines, based on the comparison result between the total index value and the threshold value, whether an object exists at a height at which there is a possibility of collision between the vehicle and the object.

[0321] In the second embodiment described above, the Fig. 14 is configured such that, when a plurality of objects are present in the vicinity of the mobile object, the collision determination unit 18 specifies an object from the plurality of objects whose azimuth angle detected by the azimuth angle detection unit 16 coincides with the traveling direction of the mobile object, and determines whether or not the specified object is present at a height at which there is a possibility of collision with the mobile object. Therefore, the Fig. 14 shown signal processing device 4 similar to that in Fig. 1, the signal processing device 4 can determine, based on the reception signal of the reflected wave received by only one receiving unit in the multipath environment, whether or not an object is present at a height where there is a possibility of collision between the mobile object and the object. In addition, the signal processing device 4 shown in Fig. 14 can determine only the objects that may collide with the mobile object and omit unnecessary determination processing when there are a plurality of objects in the vicinity of the mobile object.

[0322] It should be noted that free combinations of the embodiments, modifications to any component of the embodiments, or omission of any component in the embodiments are possible within the scope of the disclosure. INDUSTRIAL APPLICABILITY

[0323] The present disclosure is suitable for a signal processing device, a signal processing method and a radar device. LIST OF REFERENCE SYMBOLS

[0324] 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: Range interval calculation unit, 14a: Peak detection unit, 14b: Elevation angle calculation unit, 14c: Travel time calculation unit, 14d: Range interval calculation processing unit, 15: Altitude standard deviation calculation unit, 15a: Peak detection unit, 15b: Altitude calculation unit, 15c: Standard deviation calculation processing unit, 16: Azimuth angle detection unit, 16a: Peak detection unit, 16b: Azimuth angle detection processing unit, 17: Collision determination unit, 17a: First-evaluation calculation unit, 17b: Second-evaluation calculation unit, 17c: Determination processing unit, 18: Collision determination unit, 18a: First-evaluation calculation unit, 18b: Second-evaluation calculation unit,18c: Determination processing unit, 21: Memory circuit, 23: Map generation circuit, 24: Distance interval calculation circuit, 25: Altitude standard deviation calculation circuit, 26: Azimuth angle detection circuit, 27: Collision determination circuit, 28: Collision determination circuit, 31: Memory, 32: Processor, QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2012-189474 A

[0005]

Claims

[1] Signal processing device comprising: a map generation unit for acquiring a reception signal of a reflected wave from a receiving unit that receives the reflected wave from an object located in the vicinity of a mobile object, and generating a range-Doppler map indicating a signal strength level of the reception signal; an altitude standard deviation calculation unit for calculating a standard deviation of an altitude at which the object is located based on the range Doppler map generated by the map generation unit; and a collision determination unit for determining whether or not the object is at an altitude at which there is a possibility of collision between the mobile object and the object, based on the standard deviation calculated by the altitude standard deviation calculation unit. [2] The signal processing device according to claim 1, wherein the altitude standard deviation calculation unit calculates an altitude at each of a plurality of times at which the object exists based on the range Doppler map generated by the map generation unit, and calculates a standard deviation of the altitude from the altitudes at the plurality of times. [3] Signal processing device according to claim 1, further comprising: a distance interval calculation unit for calculating a distance interval at which a direct wave from the object contained in the reflected wave and a multipath wave from the object contained in the reflected wave interfere with each other, based on a distance Doppler map generated by the map generation unit, wherein the collision determination unit determines whether or not the object is at the height at which there is a possibility of collision between the mobile object and the object, based on the distance interval calculated by the distance interval calculation unit and the standard deviation calculated by the altitude standard deviation calculation unit. [4] The signal processing device according to claim 3, wherein the distance interval calculating 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 attenuate each other as the distance interval at which the direct wave and the multipath wave interfere with each other. [5] The signal processing device according to claim 3, wherein the collision determination unit calculates a first score according to the distance interval calculated by the distance interval calculation unit, calculates a second score according to the standard deviation calculated by the altitude standard deviation calculation unit, calculates a total index value which is a sum of the first score and the second score, and determines whether or not the object is at the altitude at which there is a possibility of collision between the mobile object and the object based on a comparison result between the total index value and a threshold value. [6] Signal processing device according to claim 1, further comprising: an azimuth angle detecting unit for detecting an azimuth angle of the object with respect to the mobile object based on the range Doppler map generated by the map generating unit, wherein the collision determination unit determines whether or not the object is at a height at which there is a possibility of collision between the mobile object and the object only when the azimuth angle detected by the azimuth angle detection unit coincides with a traveling direction of the mobile object. [7] The signal processing device according to claim 6, wherein when there are a plurality of objects in the vicinity of the mobile object, the collision determination unit specifies an object whose azimuth angle detected by the azimuth angle detection unit coincides with the traveling direction of the mobile object among the plurality of objects, and determines whether or not the specified object is located at the height at which there is a possibility of collision with the mobile object. [8] Signal processing methods comprising: Acquiring, by a map generating unit, a reception signal of a reflected wave from a receiving unit that receives the reflected wave from an object located in the vicinity of a mobile object, and generating a range Doppler map indicating a signal strength level of the reception signal; Calculating, by an altitude standard deviation calculation unit, a standard deviation of an altitude at which the object is located based on the range Doppler map generated by the map generation unit; and Determining, by a collision determination unit, whether or not the object is at an altitude at which there is a possibility of collision between the mobile object and the object, based on the standard deviation calculated by the altitude standard deviation calculation unit. [9] Radar device comprising: a receiving unit for receiving a reflected wave from an object located in the vicinity of a mobile object; a map generation unit for acquiring a reception signal of the reflected wave from the reception unit and generating a range Doppler map indicating a signal strength level of the reception signal; an altitude standard deviation calculation unit for calculating a standard deviation of an altitude at which the object is located based on the range Doppler map generated by the map generation unit; and a collision determination unit for determining whether or not the object is at an altitude at which there is a possibility of collision between the mobile object and the object, based on the standard deviation calculated by the altitude standard deviation calculation unit.

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