SIGNAL PROCESSING EQUIPMENT, SIGNAL PROCESSING METHOD AND RADAR EQUIPMENT

Abstract

Signal processing equipment, comprising: a map generation unit (13) to acquire a received signal of a reflected wave from a receiving unit which receives the reflected wave from an object located in the vicinity of a mobile object, and to generate a distance Doppler map which indicates a signal strength level of the received signal; an altitude standard deviation calculation unit (15) to calculate 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); a distance interval calculation unit (14) to calculate a distance interval where 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 (13); and a collision determination unit (17, 18) 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) and the distance interval calculated by the distance interval calculation unit (14).

Description

TECHNICAL AREA

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

[0002] There is a radar system (hereinafter referred to as the "conventional radar system") that determines whether or not an object is at a height where there is a possibility of collision between it and a moving object. There is a driver assistance system that has the function of braking a moving object when a determination result from the conventional radar system is acquired, and the determination result indicates that an object is at a height where there is a possibility of collision. In a multipath environment, where a multipath wave from a target object is present in a reflected wave from the target object in addition to a direct wave from the target object, the accuracy of the conventional radar system's determination of the target object's height deteriorates, and as a result, the conventional radar system may make an erroneous determination.

[0003] Patent literature 1, for example, discloses a radar device which determines the altitude of a target object, which is an object.

[0004] The radar device disclosed in patent literature 1 comprises a plurality of sensor units, a variance calculation unit, and a data selection unit to suppress deterioration in the determination accuracy of an altitude in a multipath environment. Each sensor unit comprises a transmitting and receiving unit that receives a wave reflected from a target object, and a position measuring unit that measures the altitude of the target object based on a received signal of the reflected wave. The variance calculation unit calculates a variance of the altitude measured by the sensor unit included in any combination comprising all or some of the plurality of sensor units.The data selection unit selects from a multitude of combinations one that minimizes the variance calculated by the variance calculation unit, 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.

[0005] Patent document 2 discloses a radar device for receiving a reflected wave from an object and for deriving a stationary target, comprising a height detection unit and a determination unit. The height detection unit detects the height of the stationary target. The determination unit determines, based on the degree of height variation of the stationary object, whether the stationary target constitutes an obstacle for a vehicle equipped with the radar device. Patent document 3 discloses a radar system capable of distinguishing stationary objects from non-stationary objects based on the geometric relationship between the determined distance and the Doppler frequency. Patent document 4 discloses a method for determining whether objects detected by a radar device are located on the ground or at a height. REFERENCE LIST PATENT LITERATURE Patent literature 1: JP 2012 - 189 474 A Patent literature 2: JP 2019 - 020 167 A Patent literature 3: EP 2 952 926 A1 Patent literature 4: DE 698 29 777 T2 SUMMARY OF THE INVENTIONAL PROBLEM

[0006] The radar device disclosed in patent literature 1 has the problem that it is necessary to include a large number of sensor units.

[0007] The present disclosure was made to solve the above problems, and one objective of the present disclosure is to provide a signal processing device capable of determining, on the basis of a received signal of a reflected wave received by only one receiving unit in a multipath environment, whether or not an object is present at a height where 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 comprises a map generation unit for acquiring a received signal of a reflected wave from a receiving unit which receives the reflected wave from an object located in the vicinity of a mobile object, and for generating a distance Doppler map which indicates a signal strength level of the received 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 distance Doppler map generated by the map generation unit;a distance interval calculation unit to calculate 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; and a collision determination unit to determine whether or not the object is at a height at which 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 and the distance interval calculated by the distance interval calculation unit. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0009] According to the present disclosure, in a multipath environment it is possible to determine, based on a received signal of a reflected wave received by only one receiving unit, whether an object is at a height where there is a possibility of collision between a mobile object and the object. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a configuration representation illustrating a radar device according to a first embodiment. Fig. Figure 2 is a hardware configuration representation illustrating the hardware of a signal processing device 4 according to the first embodiment. Fig. 3 is a hardware configuration representation of a computer in a case where the signal processing device 4 is implemented by software, firmware or the like. Fig. Figure 4 is a flowchart showing a signal processing procedure, which is a processing sequence of the signal processing device 4. Fig. Figure 5 is an explanatory illustration showing an example of an RD map generated by a map generation unit 13. Fig. Figure 6 is an explanatory representation showing a positional relationship between a vehicle and an upper object and a wave reflected from the upper object. Fig. Figure 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 received signal in a case where a direct wave and a multipath wave are superimposed. Fig. Figure 8 is an explanatory representation which provides an example of how to define a first threshold ThUP,r shows. Fig. Figure 9 is an explanatory representation that provides an example of setting a second threshold Th DW,r shows. Fig. Figure 10 is an explanatory representation showing an example of angle measurements of elevation angles of an upper object, a front object and a lower object, which are objects. Fig. Figure 11 is an explanatory representation showing an example of standard deviations of height positions of an upper object, a front object, and a lower object, which are objects. Fig. Figure 12 is an explanatory representation 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. Figure 13 is a flowchart, depicting a determination processing of a determination processing unit 17c. Fig. Figure 14 is a configuration diagram illustrating a radar device according to a second embodiment. Fig. Figure 15 is a hardware configuration representation showing the hardware of the signal processing device 4 according to the second embodiment. Fig. Figure 16 is an explanatory illustration showing a variety of objects that have different azimuth angles in relation to a vehicle. DESCRIPTION OF THE EXECUTION FORMS

[0010] In order to explain the present disclosure in more detail below, modes for carrying out the present disclosure are described with reference to the accompanying drawings. First embodiment

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

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

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

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

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

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

[0017] 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 received signals from reflected waves at a multitude of times from the antenna 2.

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

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

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

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

[0023] The signal processing unit 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 signpost, and a pedestrian bridge.

[0025] Storage unit 11, for example, is defined by a Fig. 2. Memory circuit 21 is implemented as shown.

[0026] In addition to each digital signal output by 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, a height standard deviation calculation unit 15, an azimuth angle detection unit 16 and a collision detection unit 17.

[0028] The map generation unit 13, for example, is characterized by a Fig. 2 map generation circuit 23 is implemented.

[0029] The map generation unit 13 acquires digital signals from the receiving unit 1, which are acquired at a multitude of times, as received signals of reflected waves at a multitude of times.

[0030] The map generation unit 13 generates an area Doppler map (hereinafter referred to as the "RD map") from the digital signal, indicating the signal strength level of the received signal. The RD map is a two-dimensional map that displays the signal strength level of the received signal according to a relative distance or spacing 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 acquisition unit 16.

[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 comprises 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 in which 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. This distance interval can be either a distance interval in which the direct wave and the multipath wave reinforce each other, or a distance interval in which the direct wave and the multipath wave attenuate each other.

[0035] The distance interval calculation unit 14 outputs distance interval information, specifying the calculated distance interval, to the collision detection unit 17.

[0036] The peak detection unit 14a detects a peak in 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 that is greater than a threshold value Th CFAR , which refers to a constant false alarm rate (CFAR), among a variety of signal strength levels indicated as a peak signal strength level in the RD map generated by the map generation unit 13. Among the variety of signal strength levels displayed in the RD map, the relative distance, which refers to a signal strength level greater than the threshold Th, is 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, specifying the relative distance with respect to the detected peak and the relative velocity with respect to the detected peak, to the elevation angle calculation unit 14b and the time-of-flight distance calculation unit 14c, respectively.

[0039] The elevation angle calculation unit 14b calculates a variety of elevation angles of the object in relation to the vehicle when the direct wave and the multi-way wave interfere with each other, based on the detection information output by the peak detection unit 14a.

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

[0041] The elevation angle calculation unit 14b determines the number of arriving waves based on the number of eigenvalues ​​greater than the strength of thermal noise and calculates the elevation angle of the object based on this number of arriving waves. For example, a multiple signal classification (MUSIC) method or signal parameter determination using a rotation-invariant technique (ESPRIT) can be used for determining the direction of arrival. The MUSIC or 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, displaying the calculated elevation angle, to the travel time distance calculation unit 14c and the distance interval calculation processing unit 14d, respectively.

[0043] Furthermore, the elevation angle calculation unit 14b can initiate the storage of the elevation angle information in the storage unit 11.

[0044] The transit time calculation unit 14c calculates a multitude of transit times of the direct wave when the direct wave and the multipath wave interfere with each other, based on the detection information output by the peak detection unit 14a and the elevation angle information output by the elevation angle calculation unit 14b.

[0045] The transit time calculation unit 14c outputs transit time information, specifying the multitude of calculated transit times, to the distance interval calculation processing unit 14d.

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

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

[0048] The distance interval calculation processing unit 14d outputs distance interval information, specifying the distance interval, to the collision detection unit 17.

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

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

[0051] The elevation standard deviation calculation unit 15 calculates the standard deviation of an elevation 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 detection unit 17.

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

[0054] The peak detection unit 15a outputs detection information, which specifies 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 elevation calculation unit 15b calculates an elevation at a multitude of times when the object is present, based on the data provided by the peak detection unit 15a.

[0056] The altitude calculation unit 15b outputs altitude information, which specifies the altitudes at a multitude of times, to the standard deviation calculation processing unit 15c.

[0057] The standard deviation calculation processing unit 15c calculates a standard deviation of the elevation from the elevations at the multitude of time points specified by the elevation information provided by the elevation calculation unit 15b.

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

[0059] The azimuth angle detection unit 16 is, for example, provided by a Fig. 2 Azimuth angle detection circuit 26 is implemented.

[0060] The azimuth angle detection unit 16 comprises a tip 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 in relation 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, specifying the azimuth angle of the object, to the collision detection unit 17.

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

[0064] The tip detection unit 16a outputs detection information, which in each case specifies the relative distance with respect to the detected tip and the relative velocity with respect to the detected tip, to the azimuth angle detection processing unit 16b.

[0065] In signal processing unit 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 only 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 use detection information output by the single peak detection unit.

[0066] The azimuth angle detection processing unit 16b calculates a variety of elevation angles of the object in relation to the vehicle when the direct wave and the multi-way wave interfere with each other, based on the detection information output by the tip detection unit 16a.

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

[0068] The azimuth angle detection processing unit 16b determines the number of arriving waves based on the number of eigenvalues ​​greater than the thermal noise level and calculates the object's azimuth angle based on this number of arriving waves. For example, the MUSIC or ESPRIT method can be used for determining the direction of arrival. The object's azimuth angle can then be determined using either the MUSIC or ESPRIT method.

[0069] The azimuth angle detection processing unit 16 outputs azimuth angle detection information, which specifies the azimuth angle of the object, to the collision detection unit 17.

[0070] The collision detection unit 17 is, for example, equipped with a Fig. 2 Collision detection circuit 27 is implemented.

[0071] The collision detection unit 17 comprises a first assessment calculation unit 17a, a second assessment calculation unit 17b and a determination processing unit 17c.

[0072] If the azimuth angle specified by the azimuth angle information output by the azimuth angle detection unit 16 matches the direction of travel of the vehicle, the collision detection unit 17 determines whether or not an object is at an altitude where 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 agreement between the azimuth angle and the vehicle's direction of travel means that a situation arises in which the vehicle and the object overlap on the horizontal plane when the vehicle is moving. Conversely, a mismatch between the azimuth angle and the vehicle's direction of travel means that a situation in which the vehicle and the object overlap on the horizontal plane when the vehicle is moving does not occur.

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

[0075] Furthermore, the collision detection unit 17 can initiate the storage of the determination result in the storage unit 11.

[0076] The first evaluation calculation unit 17a determines whether or not the azimuth angle specified by the azimuth angle information output by the azimuth angle detection unit 16 corresponds to the direction of travel of the vehicle.

[0077] If the azimuth angle matches the direction of travel of the vehicle, the first assessment calculation unit 17a calculates a first assessment according to the distance interval calculated by the distance interval calculation unit 14.

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

[0079] The second evaluation calculation unit 17b determines whether or not the azimuth angle specified by the azimuth angle information output by the azimuth angle detection unit 16 corresponds to the direction of travel of the vehicle.

[0080] If the azimuth angle matches the direction of travel of the vehicle, the second assessment calculation unit 17b calculates a second assessment 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 an overall index value, which is composed of the sum of the first assessment calculated by the first assessment calculation unit 17a and the second assessment calculated by the second assessment calculation unit 17b.

[0083] The determination processing unit 17c determines whether or not the object is at a height where 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, if the total index value is greater than a first total threshold Th1, the determination processing unit 17c determines that the object is in a position higher than the vehicle and that the object is not at a height where there is a possibility of collision between the vehicle and the object.

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

[0086] If the total index value is equal to or less than the first total threshold Th1 and the total index value is equal to or greater than the total threshold Th2, the determination processing unit 17c determines that an object is 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] Furthermore, the determination processing unit 17c can initiate the storage of the determination result in the storage unit 11.

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

[0090] The determination result output unit 5 acquires the determination result output by the collision determination unit 17 of the signal processing unit 4 and outputs the determination result, for example, to a vehicle speed control unit (not shown). The vehicle speed control unit is, for example, a device that controls the vehicle's speed, and if the determination result of the signal processing unit 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 unit controls the vehicle's speed 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 acquisition unit 16 and the collision detection unit 17, which are components of the signal processing unit 4, are each implemented by dedicated hardware, as shown in Fig. 2 shown. That is, it is assumed that the signal processing device 4 is implemented by the storage circuit 21, the map generation circuit 23, the distance interval calculation circuit 24, the altitude standard deviation calculation circuit 25, the azimuth angle detection circuit 26 and the collision detection 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 disk (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 detection circuit 27 each correspond, for example, to 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; rather, the signal processing device 4 can 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 main memory. The computer refers to the 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 representation 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 memory unit 11 is configured in the computer's main memory 31. A program that causes the computer to perform 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 detection unit 17 is stored in the main memory 31. Subsequently, the computer's processor 32 executes the program stored in the main memory 31.

[0098] Furthermore, it illustrates Fig. 2 an example in which each of the components of the signal processing facility 4 is implemented by dedicated hardware, and Fig. Figure 3 illustrates an example where 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 located in Fig. 1 is shown, described.

[0100] A transmission unit (not shown) integrated into the radar system emits radio waves towards an object located near the vehicle. The transmission unit emitting radio waves towards an object can be a device located outside the radar system.

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

[0102] Antenna 2 of receiver unit 1 receives a reflected wave from an object that is present in the vicinity of the vehicle.

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

[0104] The ADC unit 3 acquires the received signals r(t) of the reflected waves at the multitude 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 unit 4 as a received signal of the reflected wave.

[0107] Fig. Figure 4 is a flowchart showing a signal processing procedure, which is a processing sequence of the signal processing device 4.

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

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

[0110] The card generation unit 13 generates the RD card, which displays the signal strength level of the received signal by performing a Fourier transform on the digital signal r. D(t) in a distance direction and a Doppler velocity direction (step ST1 in Fig. 4).

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

[0112] In Fig. Figure 5 represents the horizontal axis as a Doppler velocity, which is a relative speed between the vehicle and the object, and the vertical axis as 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 speed. Fig. In section 5, the difference in shading represents the difference in signal strength level. The in Fig. The RD map shown in point 5 indicates that a single object is located in the vicinity of the vehicle.

[0113] The relative speed of the in Fig. The RD map shown in section 5 is subdivided, for example, into V, and the relative distance of the RD map is subdivided, for example, 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 acquisition unit 16.

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

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

[0117] In the example of Fig. 6. Antenna 2 is located in a position where the height above the ground H R is, and the upper object is located in 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. For the sake of simplicity, however, only the multipath wave reflected specularly from the ground is shown. The reflection position of the multipath wave on the ground is a position at which the distance from the ground to antenna 2 is equal to R. g,R is, and is a position in which the distance from the ground to the upper object is equal to 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 will be referred to as ground distance.

[0119] The elevation angle of the upper object relative 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 each θ EL,MP .

[0120] The received signal s of 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 emitted by a transmission unit (not shown) contained in the radar device, and c is a speed of light.

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

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

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

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

[0126] The elevation angle θ EL the upper object in relation 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 The multipath wave is expressed by the following expression (5). sinθEL=HT−HRRs tanθEL,MP=HRRg,R=HTRg,T

[0127] If 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) applies. Rs−RMP=mλ

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

[0129] By transforming expression (4), the runtime distance R is obtained. 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 path R represented in expression (2) can be MP the multipath wave is 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) with expression (6), sinθ EL,m In a case where the direct wave and the multipath wave interfere with each other, this is expressed by the following expression (11). Therefore, the elevation angle θ EL,m, when 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 θEL,m=arcsin(HT−HRHT+HR+mλsinθEL,MP)=arcsin(HT−HRHT+HR+mλsin(arctan(HR+HTRg)))

[0132] Using the elevation angle θ EL,m In a case where the direct wave and the multipath wave interfere with each other, the travel distance R S,m 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, the elevation angle θ is used. EL,m the ground distance R g,m between 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. Figure 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 received signal s in a case where the direct wave and a multipath wave are superimposed.

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

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

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

[0138] The distance interval between peaks is a distance interval in which the direct wave and the multipath wave reinforce each other. The distance interval between troughs is a distance interval in which the direct wave and the multipath wave attenuate 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 reinforce each other moderately, but in the present application, the distance interval between peak and peak is considered to be a distance interval in which 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 weaken moderately, 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 weaken each other.

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

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

[0141] The floor distance R g,m (m = 0, ±1, ±2, ..., ±M), when the direct wave and the multipath wave interfere with each other, can be determined on the basis of 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 can be used to determine 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 calculated as shown 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 an increasing distance interval ΔR m or a diminishing distance interval ΔR m as a distance interval in which the direct 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 provides distance interval information, specifying the calculated distance interval ΔR m , to the collision detection unit 17.

[0146] The following describes the calculation process for the distance interval ΔR. m further described by the distance interval calculation unit 14.

[0147] Among the V × L signal strength levels SL specified in the RD card 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 top SL peak,m of 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 is a signal strength level that refers to a wave reflected by an object located in the vicinity of the vehicle.

[0149] The tip detection unit 14a provides detection information, each of which is directed to the tip SL peak,m relative velocity v and a tip SL peak,m Specify the relative distance I, to the elevation angle calculation unit 14b and the run-time distance calculation unit 14c.

[0150] The elevation angle calculation unit 14b acquires the acquisition information from the peak acquisition 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] In particular, the elevation angle calculation unit 14b calculates the eigenvalue of the correlation matrix by performing the arrival direction determination processing using the correlation matrix and the eigenvector of the received signal s based on the acquisition information.

[0153] The elevation angle calculation unit 14b determines the number of arriving waves based on the number of eigenvalues ​​that are greater 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 received.

[0154] The elevation angle calculation unit 14b provides the elevation angle information, displaying the elevation angle θ. EL,m (m = 0, ±1, ±2, ..., ±M), each to the runtime distance calculation unit 14c and the distance interval calculation processing unit 14d.

[0155] The time-of-flight distance calculation unit 14c acquires the acquisition information from the peak acquisition unit 14a and acquires the elevation angle information from the elevation angle calculation unit 14b.

[0156] The runtime distance 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 acquisition information, by the following expression (16) as runtime distance R S,m(m = 0, ±1, ±2, ..., ±M) of the direct wave is replaced and the elevation angle θ is used. EL,m , which is specified by the elevation angle information, is replaced by expression (16). The elevation H R The location where antenna 2 is installed is stored, for example, in the internal working memory of the time-of-flight distance calculation unit 14c. In the multipath environment, the elevation angle θ can be EL,m contains an error, and therefore the altitude H may also be incorrect. T,m The object contains an error. HT,m=RS,m×sin(θEL,m)+HR

[0157] The runtime distance 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 multitude of direct wave propagation paths when the direct wave and the multipath wave interfere with each other. The propagation path calculation unit 14c provides the propagation path information, specifying the propagation path 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 runtime distance R. S,m , which relate to the m-th ground distance R g,m refers to, 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 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 covering the m-th travel time distance R S,m and the (m+1)th runtime distance R S,m+1 replaced by expression (15).

[0161] The distance interval calculation processing unit 14 provides distance interval information, specifying the distance interval ΔR m , to the collision detection unit 17.

[0162] Here, the distance interval calculation processing unit 14d calculates the distance interval ΔR. m from the m-th run-time path R S,m and the (m+1)th runtime distance R S,m+1However, this is just one example, and the distance interval calculation processing unit 14d can handle 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 up 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 elevation standard deviation calculation unit 15 is acquired by 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 gives the calculation result of the standard deviation H std to the collision detection unit 17.

[0168] The following describes the calculation process for the standard deviation H. std further described by the altitude standard deviation calculation unit 15.

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

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

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

[0172] The altitude calculation unit 15b calculates the travel time distance 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, similar to the time-of-flight 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 multitude of times by measuring the runtime distance R S,m , the elevation angle θ EL,m , and the altitude H R replaced by expression (16). The altitude H R For example, it is stored in the internal working memory of the altitude calculation unit 15b.

[0175] The altitude calculation unit 15b gives 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 to the multitude of time points expressed by the following expression (17).

[0178] The standard deviation calculation processing unit 15c gives the calculation result of the standard deviation H. std to the collision detection 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 detection unit 16 detects an azimuth angle of an object in relation to the vehicle based on the RD map.

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

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

[0184] The tip detection unit 16a detects the tip SL peak,m of 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 tip detection unit 16a provides detection information, each indicating the relative distance with respect to the detected tip SL peak,m and the relative velocity in relation to the detected peak SL peak,mSpecify, to the azimuth angle detection processing unit 16b.

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

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

[0188] In particular, the azimuth angle detection processing unit 16b calculates the eigenvalue of the correlation matrix by performing the arrival direction determination processing using the correlation matrix and the eigenvector of the received signal s on the basis of the detection information output by the tip detection unit 16a.

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

[0190] The azimuth angle detection processing unit 16 outputs the azimuth angle detection information, which specifies the azimuth angle of the object, to the collision detection unit 17.

[0191] The collision detection unit 17 acquires the distance interval ΔR m from the distance interval calculation unit 14, acquires the standard deviation H std the altitude is obtained 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 specified by the azimuth angle information matches the vehicle's direction of travel, the collision detection unit 17 determines whether or not the object is at a height where 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 detection unit 17 outputs the detection result to the detection result output unit 5.

[0194] The following section describes in more detail the determination process by the collision determination unit 17.

[0195] The first assessment calculation unit 17a determines whether or not the azimuth angle specified by the azimuth angle information corresponds to the direction of travel of the vehicle.

[0196] If the azimuth angle matches the vehicle's direction of travel, the first assessment calculation unit 17a sets a first threshold Th UP,r , which specifies the boundary between the upper object and the front object, and a second threshold Th DW,r , which defines the boundary between the object in front and the object below for each distance r to the ground. r is an integer equal to or greater than 1.

[0197] The following section describes in more detail the threshold determination process using the initial assessment calculation unit 17a.

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

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

[0200] For example, an internal memory of the first assessment calculation unit 17a stores a distance interval ΔR FRO,r for any ground distance r, if an object present in the vicinity of the vehicle is the object in front, as expressed in the following expression (18). For example, the altitude H T,FRO of the object in front lower than the altitude H Celthe vehicle's ceiling. 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)(1sinθEL,m+1−1sinθEL,m)

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

[0202] Furthermore, the first assessment calculation unit 17a sets the second threshold Th DW,r , which is the boundary between the foreground object and the bottom object, for each ground distance r, using the distance interval ΔR FRO,r for each ground distance r fixed, 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 defines the first threshold Th UP,r larger than the distance interval ΔR FRO,r in relation to the object in front. The altitude corresponding to the distance interval ΔR FRO,r This corresponds to a higher altitude than H. Cel the ceiling of the vehicle and as close as possible to the altitude H Cel . Thus, the first threshold Th UP,r set to a distance interval corresponding to the altitude H T1 corresponds to a slightly higher altitude than H Cel , as for example in Fig. 8 shown. Fig. Figure 8 is an explanatory representation which provides an example of how to define the first threshold Th UP,r shows. In expression (20), P2 is a coefficient less than 1 and a coefficient that defines the second threshold Th.DW,r smaller than the distance interval ΔR FRO,r in relation to the object in front. The altitude corresponding to the distance interval ΔR FRO,r This corresponds to a level that is preferably lower than the minimum ground level H. FLO of the vehicle and as close as possible to the minimum ground level H FLO . Thus, the second threshold Th DW,r set to a distance interval corresponding to the altitude H T1 ' corresponds to which is slightly lower than the minimum ground level H FLO , as for example in Fig. 9 shown. Fig. Figure 9 is an explanatory representation that provides an example of how to define the second threshold Th DW,r shows.

[0204] The first-assessment calculation unit 17a acquires the distance interval ΔR m (m = 0, ±1, ±2, ..., ±M) from the distance interval calculation unit 14.

[0205] The first assessment calculation unit 17a specifies a distance interval ΔR r , which corresponds to the ground distance r, among the distance intervals ΔR0 to ΔR M For example, if the peak with the shorter ground distance is among the two peaks that define the distance interval ΔR m Specifying m = 5, which belongs to the ground distance “3”, the first assessment calculation unit 17a sets the distance interval ΔR m from m = 5 to the distance interval ΔR r of r = 3.

[0206] After setting the first threshold Th UP,r and the second threshold Th DW,r The first-assessment 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 Th DW,r for each floor removal r.

[0207] If the distance interval ΔRr is greater than the first threshold Th UP,r , the first valuation calculation unit 17a sets the value of the first valuation to a first value.

[0208] 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 valuation calculation unit 17a sets the value of the first valuation to a second value.

[0209] If the distance interval ΔR r is smaller than the second threshold Th DW,r The first valuation calculation unit 17a sets the value of the first valuation to a third value. The following applies: the first value > the second value > the third value.

[0210] The first assessment calculation unit 17a outputs the first assessment to the determination processing unit 17c.

[0211] Here, the first assessment calculation unit 17a sets the first assessment 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 one example, and the first-assessment calculation unit 17a may receive a larger first assessment if the distance interval ΔR r is larger by using the distance interval ΔR r replaced by a multifunctional expression for calculating the initial valuation.

[0212] The second assessment calculation unit 17b determines whether or not the azimuth angle specified by the azimuth angle information corresponds to the direction of travel of the vehicle.

[0213] If the azimuth angle matches the vehicle's direction of travel, the second-evaluation calculation unit 17b sets a third threshold Th. UP',r, which specifies the boundary between the upper object and the front object, and a fourth threshold Th DW',r , which defines the boundary between the foreground object and the bottom object, for each ground distance r.

[0214] The following section describes in more detail the threshold determination processing by the Second Assessment Calculation Unit 17b.

[0215] Fig. Figure 10 is an explanatory representation showing an example of angle measurements of elevation angles of an upper object, a front object and a lower object, which are objects.

[0216] 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.

[0217] Δ 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 o is a measured angle value of the elevation angle of the lower object.

[0218] As from Fig. As can be seen in Figure 10, with increasing height of the object, it is more likely that the angular measurement accuracy of the elevation angle will deteriorate due to the influence of the multipath wave.

[0219] Fig. Figure 11 is an explanatory representation showing an example of standard deviations of height positions of an upper object, a front object, and a lower object, which are objects.

[0220] 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 height.

[0221] Δ is a standard deviation of the height of the upper object, □ is a standard deviation of the height of the front object, and o is a standard deviation of the height of the lower object.

[0222] As from Fig. As can be seen in Figure 11, with increasing elevation of the object, it is more likely that the standard deviation of the object's elevation will worsen due to the influence of the multipath wave, similar to the measured angular value of the elevation angle. Thus, the standard deviation of the elevation of the upper object is greater than the standard deviation of the elevation of the object in front. Furthermore, the standard deviation of the elevation of the object in front is greater than the standard deviation of the elevation of the lower object.

[0223] In the example of Fig. 11 will be the third threshold Th UP',rbetween the standard deviation of the elevation of the upper object and the standard deviation of the elevation of the foreground 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 lower object for each ground distance r.

[0224] 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 height of the foreground object.

[0225] For example, an internal memory of the Second Assessment Calculation Unit 17b stores a standard deviation H FROstd,r the altitude for each ground distance r, if an object present in the vicinity of the vehicle is the object in front.

[0226] The second assessment calculation unit 17b sets the third threshold ThUP',r, which defines the boundary between the upper object and the foreground object, for each ground distance r using the standard deviation H FROstd,r the elevation for each ground distance r, as expressed in the following expression (21).

[0227] Furthermore, the second assessment calculation unit 17b sets the fourth threshold Th DW',r , which defines the boundary between the foreground object and the lower ground object, for each ground distance r using the standard deviation H FROstd,r the elevation for each ground distance r, as expressed in the following expression (22). ThUP',r=P3×HFROstd,r ThDW',r=P4×HFROstd,r

[0228] In expression (21), P3 is a coefficient greater than 1 and a coefficient that defines the third threshold Th UP',r greater than the standard deviation H FROstd,r the elevation relative to the object in front. The third threshold Th UP',ris preferably higher than altitude H Cel the ceiling of the vehicle and as close as possible to the altitude H Cel .

[0229] In expression (22), P4 is a coefficient less than 1 and a coefficient that defines the fourth threshold Th DW',r smaller than the standard deviation H FROstd,r the elevation relative to the object in front. 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 level H FLO .

[0230] The second assessment calculation unit 17b acquires the calculation result of the standard deviation H. std of the altitude from the altitude standard deviation calculation unit 15.

[0231] 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 as the standard deviation H FROstd,r the ground distance r fixed.

[0232] For example, if the ground distance is the standard deviation H std If the altitude corresponds to a ground distance of r = 7, the standard deviation H std as the standard deviation H FRO,td,7 determined. If the ground distance is the standard deviation H std If the altitude corresponds to a ground distance of r = 8, the standard deviation H std as the standard deviation H FROstd,8 determined.

[0233] After the third threshold Th UP',r and the fourth threshold Th DW',r The second assessment calculation unit 17b compares the standard deviation H, as determined. 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 floor removal r.

[0234] If the standard deviation H FROstd,r the altitude is greater than the third threshold Th UP',r , the second assessment calculation unit 17b sets the value of the second assessment to a fourth value.

[0235] The second-rating calculation unit 17b sets the value of the second rating to a fifth value 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 .

[0236] If the standard deviation H FROstd,r the altitude is lower than the fourth threshold Th DW',r The second assessment calculation unit 17b sets the value of the second assessment to a sixth value. The fourth value > the fifth value > the sixth value.

[0237] The second evaluation calculation unit 17b outputs the second evaluation to the determination processing unit 17c.

[0238] Here, the second assessment calculation unit 17b determines the second assessment according to the comparison result between the standard deviation H FROstd,r the altitude and the third threshold Th UP',r as well as the fourth threshold Th DW',r fixed. However, this is only one example, and the second assessment calculation unit 17b can have a larger second assessment with increasing size of the standard assessment H. FRostd,r obtained by calculating the standard deviation H FROstd,r The altitude is replaced by the multifunctional expression for calculating the second assessment.

[0239] The determination processing unit 17c acquires the first valuation from the first valuation calculation unit 17a and acquires the second valuation from the second valuation calculation unit 17b.

[0240] The determination processing unit 17c calculates a total index value Ind, which is the sum of the first assessment and the second assessment.

[0241] The determination / processing unit 17c calculates the overall index value Ind here by adding the first and second assessments. However, this is only an example, and the determination / processing unit 17c can also calculate the overall index value Ind by weighting and adding the first and second assessments.

[0242] Fig. Figure 13 is a flowchart, depicting a determination processing of the determination processing unit 17c.

[0243] The determination processing unit 17c compares the total index value Ind with the first total threshold value Th1.

[0244] If the total index value Ind is greater than the first total threshold Th1 (step ST21 in Fig. 13: YES), determines the determination processing unit 17c that an object present in the vicinity of the vehicle is an upper object (step ST22 in Fig. 13).

[0245] This means that 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.

[0246] If the total index value Ind is equal to or less than the first total threshold 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.

[0247] If the total index value Ind is less than the second total threshold Th2 (step ST23 in Fig. 13: YES), determines the determination processing unit 17c that an object present in the vicinity of the vehicle is a lower object (step ST24 in Fig. 13).

[0248] This means that 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.

[0249] If the total index value Ind is equal to or greater than the second total threshold Th2 (step ST23 in Fig. 13: NO), determines the determination processing unit 17c that an object present in the vicinity of the vehicle is a front object (step ST25 in Fig. 13).

[0250] This means that the determination processing unit 17c determines that there is an object at a height where there is a possibility of collision between the vehicle and the object.

[0251] The determination processing unit 17c outputs the determination result to the determination result output unit 5.

[0252] The determination result output unit 5 acquires the determination result from the collision determination unit 17 and outputs the determination result, for example, to a vehicle speed control device not shown.

[0253] If the determination result of the collision detection unit 17 indicates that the object is at a height where there is a possibility of collision between the vehicle and the object, the vehicle speed control device controls the vehicle's speed, for example, so that the vehicle does not collide with the object.

[0254] The in Fig. The signal processing unit 4 shown in Figure 1 comprises both the distance interval calculation unit 14 and the altitude standard deviation calculation unit 15, and the collision detection 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 from 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 one example, and it is also possible that the signal processing unit 4 does not include the distance interval calculation unit 14, and the collision detection unit 17 is based on the standard deviation H calculated by the height standard deviation calculation unit 15. stddetermines whether an object is at a height where there is a possibility of collision between the vehicle and the object.

[0255] If in this case the standard deviation H FROstd,r the altitude is greater than the third threshold Th UP',r Collision detection unit 17 determines that the object in the vicinity of the vehicle is an upper object. That is, collision detection unit 17 determines that there is no object at a height where a collision between the vehicle and the object is possible.

[0256] If the standard deviation H FROstd,r the altitude is lower than the fourth threshold Th DW',rCollision detection unit 17 determines that the object in the vicinity of the vehicle is a lower object. That is, collision detection unit 17 determines that there is no object at a height where a collision between the vehicle and the object is possible.

[0257] 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 Collision detection unit 17 determines that the object present in the vicinity of the vehicle is a front object. That is, collision detection unit 17c determines that there is an object at a height where there is a possibility of collision between the vehicle and the object.

[0258] In a case where the signal processing unit 4 does not contain the distance interval calculation unit 14, the configuration can be simplified more than in a case where the signal processing unit 4 contains both the distance interval calculation unit 14 and the altitude standard deviation calculation unit 15.

[0259] In the first embodiment described above, the signal processing device 4 is configured to include the map generation unit (13), which acquires a received signal of the reflected wave from the receiving unit (1), which receives the reflected wave from the object located in the vicinity of a mobile object, and generates the distance Doppler map, which indicates a signal strength level of the received signal, and the altitude standard deviation calculation unit (15), which calculates the standard deviation of the altitude at which the object is located, based on the distance Doppler map generated by the map generation unit (13).Furthermore, the signal processing unit 4 includes the collision detection unit 17 to determine whether or not the object is located at a height where there is a possibility of collision between the mobile object and the stationary object, based on the standard deviation calculated by the height standard deviation calculation unit 15. Therefore, the signal processing unit 4 can determine, based on the received signal of the reflected wave, which is received by only one receiving unit in the multipath environment, whether or not an object is located at a height where there is a possibility of collision between the mobile object and the stationary object.

[0260] Furthermore, in the first embodiment, the signal processing unit 4 is configured to include the distance interval calculation unit 14, which calculates the distance interval in which the direct wave from the object, contained in the reflected wave, and the multipath wave from the object, contained in the reflected wave, interfere with each other, based on the distance Doppler map generated by the map generation unit 13. Furthermore, the collision detection unit 17 in the signal processing unit 4 determines whether or not an object is located at a height where there is a possibility of collision between the moving 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 the determination more than in the case where it is determined only on the basis of the standard deviation whether or not an object is at a height where there is a possibility of collision between the mobile object and the object.

[0261] In signal processing unit 4, shown in Fig. 1, the second assessment calculation unit 17b of the collision determination unit 17 sets the third threshold Th UP',r as well as the fourth threshold Th DW',r using the standard deviation H FROstd,r the elevation is fixed for each ground distance r. However, this is only an example, and the second-assessment calculation unit 17b can use the third threshold values ​​Th. UP',r as well as the fourth threshold Th DW',r using the standard deviation of the received signal strength, as in Fig. 12 shown, set.

[0262] Fig. Figure 12 is an explanatory representation 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.

[0263] 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.

[0264] As from Fig. As can be seen in Figure 12, with increasing altitude of the object, the standard deviation of the received signal strength is more likely to deteriorate due to the influence of the multipath wave, similar to the standard deviation of altitude. Therefore, the standard deviation of the received signal strength with respect to the upper object is greater than the standard deviation of the received signal strength with respect to the object in front. Furthermore, the standard deviation of the received signal strength with respect to the object in front is greater than the standard deviation of the received signal strength with respect to the object below.

[0265] In the example of Fig. 12 A temporary threshold Th is set for each ground distance r. 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 foreground 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.

[0266] For example, the second assessment calculation unit 17b calculates the third threshold Th UP',r , by setting the temporary threshold Th UP2,r is replaced by the following expression (23).

[0267] Furthermore, the second assessment calculation unit 17b, for example, calculates the fourth threshold 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

[0268] In expressions (23) to (24) each of the parameters P5, P6, P7 and P8 is a parameter for temporary threshold adjustment. Second embodiment

[0269] In a second embodiment, the signal processing device 4 is described for a case in which several objects with different azimuth angles are present with respect to the vehicle.

[0270] Fig. Figure 14 is a configuration diagram illustrating a radar device according to the second embodiment.

[0271] Fig. Figure 15 is a hardware configuration representation illustrating the hardware of a signal processing device 4 according to the second embodiment.

[0272] The in Fig. The radar device shown in Figure 14 comprises the receiving unit 1, the signal processing unit 4 and the result output unit 5.

[0273] 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 detection unit 18.

[0274] The collision detection unit 18 is, for example, equipped with a Fig. Collision detection circuit 28 shown in 15 is implemented.

[0275] The collision detection unit 18 comprises a first assessment calculation unit 18a, a second assessment calculation unit 18b and a determination processing unit 18c.

[0276] The collision detection unit 18 determines each of the azimuth angles of the multitude of objects based on the azimuth angle information output by the azimuth angle detection unit 16.

[0277] The collision detection unit 18 specifies an object whose azimuth angle matches the direction of travel of the vehicle from the multitude of objects.

[0278] For the specified object, the collision detection unit 18 determines whether or not an object is located at a height 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 height standard deviation calculation unit 15.

[0279] The collision detection unit 18 does not perform a detection process on an object whose azimuth angle does not match the direction of travel of the vehicle.

[0280] The collision detection unit 18 outputs the detection result to the detection result output unit 5.

[0281] The first evaluation calculation unit 18a specifies each of the azimuth angles of the plurality of objects based on the azimuth angle information output by the azimuth angle detection unit 16, and specifies one object whose azimuth angle matches the direction of travel of the vehicle from the plurality of objects.

[0282] The first assessment calculation unit 18a calculates the first assessment for the specified object according to the distance interval calculated by the distance interval calculation unit 14.

[0283] The first assessment calculation unit 18a outputs the first assessment to the determination processing unit 18c.

[0284] The second evaluation calculation unit 18b specifies each of the azimuth angles of the plurality of objects based on the azimuth angle information output by the azimuth angle detection unit 16, and specifies one object whose azimuth angle matches the direction of travel of the vehicle from the plurality of objects.

[0285] The Second Assessment Calculation Unit 18b calculates the second assessment for the specified object according to the standard deviation calculated by the Altitude Standard Deviation Calculation Unit 15.

[0286] The second evaluation calculation unit 18b outputs the second evaluation to the determination processing unit 18c.

[0287] Similar to the ones in Fig. 1. Determination processing unit 17c calculates the determination processing unit 18c a total index value which is composed of the sum of the first assessment calculated by the first assessment calculation unit 18a and the second assessment calculated by the second assessment calculation unit 18b.

[0288] The determination processing unit 18c determines whether or not the object is at a height where 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.

[0289] 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 acquisition unit 16 and the collision detection unit 18, which are components of the signal processing unit 4, are each implemented by dedicated hardware, as shown in Fig. Figure 15 shows that the signal processing device 4 is implemented 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 detection circuit 28.

[0290] 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 detection circuit 28 each correspond, for example, to a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA or a combination thereof.

[0291] The components of the signal processing device 4 are not limited to those implemented by dedicated hardware; rather, the signal processing device 4 can be implemented by software, firmware, or a combination of software and firmware.

[0292] In a case where the signal processing unit 4 is implemented by software, firmware, or the like, the memory unit 11 is located in the computer's main memory 31, as shown in Fig. 3, configured. A program that causes a computer to perform processing operations in the map generation unit 13, the distance interval calculation unit 14, the elevation standard deviation calculation unit 15, the azimuth angle acquisition unit 16, and the collision detection unit 18 are stored in the working memory 31. Then the Fig. 3 The processor 32 shown executes the program stored in the main memory 31.

[0293] Furthermore, it illustrates Fig. 15 an example in which each of the components of the signal processing unit 4 is implemented by dedicated hardware, and Fig. Figure 3 illustrates an example where 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.

[0294] Fig. Figure 16 is an explanatory illustration showing a variety of objects that have different azimuth angles in relation to a vehicle.

[0295] In the example of Fig. In equation 16, there are two objects, and one object is an upper object whose azimuth angle coincides with the vehicle's direction of travel. The travel distance of the direct wave from the upper object is R. S , and the travel distance of the multipath wave from the upper object is R MP .

[0296] The other object is an object whose azimuth angle does not coincide with the vehicle's direction of travel. The distance between the vehicle and the other object is R. AZ .

[0297] In the example of Fig. 16 The reflected wave received by 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.

[0298] In this case, a received signal s' of antenna 2 is expressed by the following expression (25). s'=exp(−j2πf0Rsc)+KMPexp(−j2πf0RMPc)+KAZexp(−j2πf0RAZc)

[0299] Expression (25) contains K AZ for a reflection coefficient.

[0300] If the direct wave from the upper object and the multipath wave from the upper object overlap 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 of the upper object and the reflected wave of the other object interfere with each other due to the superposition of the multipath wave of the upper object and the reflected wave of the other object, the following expression (27) applies.

[0301] Furthermore, in the event that the direct wave of the upper object and the reflected wave of the other object interfere with each other, the following expression (28) also applies. Rs−RMP=m1λ(m1=0,±1,±2,⋯) RMP−RAZ=m2λ(m2=0,±1,±2,⋯) Rs−RAZ=m3λ(m3=0,±1,±2,⋯)

[0302] The distance interval ΔR m1, when the direct wave from the upper object and the multipath wave from the lower object interfere with each other, the elevation angle θ can be determined. EL,m1 with regard to the m1-th ground distance R g,m1 and the elevation angle θ EL,m+1 with respect to the (m1+1)th ground distance R g,m1+1 calculated as shown in the following expression (29). ΔRm1=Rs,m1+1−Rs,m1=(HT,m1−HR)(1sinθEL,m1+1−1sinθEL,m1)

[0303] 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 relation to the m3-th ground distance R g,m3 and the elevation angle θ EL,m3+1 in relation to the (m3+1)th ground distance R g,m3+1 calculated as shown in the following expression (30). ΔRm3=Rs,m3+1−Rs,m3=(HT,m3−HR)(1sinθEL,m3+1−1sinθEL,m3)

[0304] The following describes the operation of the radar system located in Fig. The radar system, with the exception of the collision detection unit 18, is described in Figure 14. Fig. The radar device shown in Figure 1 is similar. Therefore, only the operation and functionality of the collision detection unit 18 are described here.

[0305] The first assessment calculation unit 18a of the collision determination unit 18 determines the azimuth angle from the azimuth angle detection unit 16.

[0306] The first evaluation calculation unit 18a specifies each of the azimuth angles of the multitude of objects based on the azimuth angle information.

[0307] The first assessment calculation unit 18a determines whether or not the azimuth angle of each object matches the direction of travel of the vehicle.

[0308] If, among the multitude of objects, there is one whose azimuth angle matches the direction of travel of the vehicle, the first assessment calculation unit 18a sets the first threshold Th UP,r and the second threshold Th DW,r for the object whose azimuth angle coincides with the vehicle's direction of travel. The procedure for setting the first threshold values ​​Th UP,r and the like, through the first assessment calculation unit 18a, is similar to the procedure for setting the first thresholds Th UP,r and the like through the in Fig. 1. First assessment calculation unit 17a.

[0309] The first assessment calculation unit 18a calculates a first assessment for an object whose azimuth angle coincides with the direction of travel of the vehicle, according to a procedure similar to that described in Fig. 1 resembles the first assessment calculation unit 17a shown.

[0310] The first assessment calculation unit 18a does not calculate the first assessment for an object whose azimuth angle does not match the direction of travel of the vehicle.

[0311] In the example of Fig. 16 calculates the first valuation calculation unit 18a the first valuation for the upper object and does not calculate the first valuation for any other object.

[0312] The second evaluation calculation unit 18b acquires the azimuth angle information from the azimuth angle acquisition unit 16.

[0313] Similar to the first-evaluation calculation unit 18a, the second-evaluation calculation unit 18b specifies each of the azimuth angles of the multitude of objects based on the azimuth angle information and determines whether or not the azimuth angle of each object matches the direction of travel of the vehicle.

[0314] If, among the multitude of objects, there is one whose azimuth angle matches the direction of travel of the vehicle, the second-evaluation calculation unit 18b sets the third threshold Th UP',r and the fourth threshold Th DW,r for the object whose azimuth angle coincides with the vehicle's direction of travel. The procedure for setting the third threshold Th UP',r and the like, through the second assessment calculation unit 18b, is similar to the procedure for setting the third threshold Th UP',r and the like through the in Fig. 1 Second assessment calculation unit 17b shown.

[0315] The second-assessment calculation unit 18b calculates a second assessment for an object whose azimuth angle coincides with the vehicle's direction of travel, using a method similar to that described in Fig. 1 resembles the first assessment calculation unit 17a shown.

[0316] The second assessment calculation unit 18b does not calculate the second assessment for an object whose azimuth angle does not match the direction of travel of the vehicle.

[0317] In the example of Fig. 16 calculates the second valuation calculation unit 18b for the upper object and does not calculate the second valuation for any other object.

[0318] Similar to the ones in Fig. 1. Determination processing unit 17c calculates the determination processing unit 18c a total index value which is composed of the sum of the first assessment calculated by the first assessment calculation unit 18a and the second assessment calculated by the second assessment calculation unit 18b.

[0319] Similar to the ones in Fig. The determination processing unit 17c shown determines the determination processing unit 18c based on the comparison result between the total index value and the threshold value whether an object is present at a height where there is a possibility of collision between the vehicle and the object.

[0320] In the second embodiment described above, the Fig. The signal processing device 4 shown in Figure 14 is configured such that, if a multitude of objects are present in the vicinity of the mobile object, the collision detection unit 18 specifies an object from the multitude of objects whose azimuth angle, detected by the azimuth angle detection unit 16, corresponds to the direction of travel of the mobile object, and determines whether or not the specified object is present at a height where there is a possibility of collision with the mobile object. Therefore, the Fig. 14 Signal processing device 4 shown, similar to the one in Fig. The signal processing device 4 shown in 1 determines, based on the received signal of the reflected wave, which is 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. Furthermore, the device shown in Fig. 14. The signal processing device 4 shown only determines the objects that could collide with the mobile object and omits unnecessary determination processing when there are a large number of objects in the vicinity of the mobile object.

[0321] It should be noted that free combinations of the embodiments, modifications to any component of the embodiments, or the omission of a component in the embodiments are possible within the scope of the disclosure. INDUSTRIAL APPLICABILITY

[0322] The present disclosure is suitable for a signal processing device, a signal processing method and a radar device. REFERENCE MARK LIST

[0323] 1: Receiving unit, 2: Antenna, 3: ADC unit, 4: Signal processing unit, 5: Result output unit, 11: Storage unit, 12: Signal processing unit, 13: Map generation unit, 14: Distance interval calculation unit, 14a: Peak detection unit, 14b: Elevation angle calculation unit, 14c: Time-of-flight distance calculation unit, 14d: Distance 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 detection unit, 17a: First Assessment Calculation Unit, 17b: Second Assessment Calculation Unit, 17c: Determination Processing Unit, 18: Collision Determination Unit, 18a: First Assessment Calculation Unit, 18b: Second Assessment 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 detection circuit, 28: Collision detection circuit, 31: Main memory, 32: Processor,

Claims

[1] Signal processing device, comprising: a map generation unit (13) to acquire a received signal of a reflected wave from a receiving unit which receives the reflected wave from an object located in the vicinity of a mobile object, and to generate a distance Doppler map which indicates a signal strength level of the received signal; an altitude standard deviation calculation unit (15) to calculate 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); a distance interval calculation unit (14) to calculate a distance interval where 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 (13); and a collision determination unit (17, 18) 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) and the distance interval calculated by the distance interval calculation unit (14). [2] Signal processing device according to claim 1, wherein The elevation standard deviation calculation unit (15) calculates an elevation at each of a plurality of times when the object is present, based on the distance Doppler map generated by the map generation unit (13), and calculates a standard deviation of the elevation from the elevations at the plurality of times. [3] Signal processing device according to claim 1, wherein the distance interval calculation unit (14) calculates a distance interval in which the direct wave and the multipath wave reinforce each other or a distance interval in which the direct wave and the multipath wave attenuate each other as the distance interval in which the direct wave and the multipath wave interfere with each other. [4] Signal processing device according to claim 1, wherein the collision detection unit (17, 18) calculates a first evaluation according to the distance interval calculated by the distance interval calculation unit (14), calculates a second evaluation according to the standard deviation calculated by the altitude standard deviation calculation unit (15), calculates a total index value which is a sum of the first evaluation and the second evaluation, 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. [5] Signal processing device according to any of the preceding claims, further comprising: an azimuth angle detection unit (16) to detect an azimuth angle of the object in relation to the mobile object based on the distance Doppler map generated by the map generation unit (13), wherein The collision detection unit (17) determines whether or not the object is at a height where there is a possibility of collision between the mobile object and the object if the azimuth angle detected by the azimuth angle detection unit (16) corresponds to a direction of travel of the mobile object. [6] Signal processing device according to claim 5, wherein, if there is a plurality of objects in the vicinity of the mobile object, the collision detection unit (18) specifies an object whose azimuth angle detected by the azimuth angle detection unit (16) corresponds to the direction of travel of the mobile object among the plurality of objects, and determines whether or not the specified object is at the height at which there is a possibility of collision with the mobile object. [7] Signal processing techniques, including: Acquire, by means of a map-generating unit (13), a received signal of a reflected wave from a receiving unit which receives the reflected wave from an object located in the vicinity of a mobile object, and generate a distance Doppler map which indicates a signal strength level of the received signal; Calculate, by means of an altitude standard deviation calculation unit (15), 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); Calculate, by a distance interval calculation unit (14), a distance interval in 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 (13); and Determine, by means of a collision determination unit (17, 18), 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) and the distance interval calculated by the distance interval calculation unit (14). [8] Radar equipment, comprising: a receiving unit to receive a reflected wave from an object located in the vicinity of a mobile object; a map generation unit (13) to acquire a received signal of the reflected wave from the receiving unit and to generate a distance Doppler map that indicates a signal strength level of the received signal; an altitude standard deviation calculation unit (15) to calculate 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); a distance interval calculation unit (14) to calculate a distance interval where 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 (13); and a collision determination unit (17, 18) 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) and the distance interval calculated by the distance interval calculation unit (14).

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