JP2010197138A - Radar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect highly precisely azimuths of many objects without increasing the number of receiving antennas. <P>SOLUTION: A control part 11 of the radar device 1 includes a transmission instruction part 111 which generates two or more transmission signals and transmits respectively the transmission signals toward mutually different areas through a transmission part 12 and a received signal processing part 114 which receives the signals corresponding respectively to the two or more transmission signals through a receiving part 13 and detects an object-existing azimuth (azimuth along which the received signal comes) with high resolution using MUSIC method per received signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to, for example, a radar apparatus that transmits a transmission signal and receives a reception signal, and detects an object based on the transmission signal and the reception signal. More specifically, for example, the present invention relates to a radar device mounted on a vehicle.

  Conventionally, in a radar apparatus that performs monopulse angle measurement, when there are a plurality of objects in the same beam, the azimuth detection error of each object is large, and the detection accuracy is reduced. Thus, various methods, devices, and the like for improving the azimuth detection accuracy of the radar device have been disclosed (see, for example, Patent Document 1).

  For example, Patent Document 1 discloses a radar apparatus that includes a monopulse angle measurement method and a high resolution angle measurement method that detects an azimuth of an object by performing a high-resolution signal processing operation such as a MUSIC (Multiple Signal Classification) method. Are listed. According to this radar apparatus, when there are only a plurality of objects, the orientation detection accuracy of the object can be improved by switching from the monopulse angle measurement method to the high resolution angle measurement method.

JP 2003-14843 A

  However, in the radar apparatus described in Patent Document 1, a high-resolution angle measurement method using the MUSIC method or the like is implemented to detect the azimuth of an object. In such a high-resolution angle measurement method, detection is performed based on the number of reception antennas. The number of possible object orientations is limited. Specifically, in the MUSIC method, if there are more objects than the number of receiving antennas, correct calculation cannot be performed.

  Therefore, when detecting the orientation of an object by implementing a high-resolution angle measurement method using the MUSIC method or the like, it is necessary to increase the number of receiving antennas and to make it possible to detect many objects. It is necessary to perform a correct operation. In particular, with the widening of the detection range of radar devices, the need to be able to detect many objects is increasing.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a radar apparatus capable of detecting the orientation of many objects with high accuracy without increasing the number of receiving antennas. Is to provide.

  In order to achieve the above object, the present invention has the following features. A first invention is a radar apparatus that transmits a transmission signal and receives a reception signal, detects an object based on the transmission signal and the reception signal, generates a plurality of transmission signals, and transmits each transmission signal. Transmitting means for transmitting the signals toward different areas, and receiving signals corresponding to the plurality of transmitting signals, respectively, and detecting a direction in which an object exists for each received received signal And a processing means.

  According to a second invention, in the first invention, a reception signal corresponding to each of the plurality of transmission signals is received, and whether or not an object exists in each of the regions corresponding to the plurality of transmission signals. An object determination unit for determining whether or not the received signal processing unit detects a direction in which the object exists only in a region where the object determination unit determines that the object exists.

  In a third aspect based on the second aspect, the detected object may collide with the vehicle when the radar apparatus is mounted on the vehicle and the object determination unit determines that the object is present. Collision determination means for determining whether or not there is provided, and the received signal processing means detects the direction in which the object exists only when the collision determination means determines that there is a possibility of collision.

  In a fourth aspect based on the first aspect, the received signal processing means detects the azimuth of the object using a high resolution azimuth detection method that detects the azimuth of the received signal with high resolution. To do.

  In a fifth aspect based on the fourth aspect, the receiving antenna has a first predetermined number of antenna elements of two or more, and the received signal processing means has an orientation that can be detected by the first predetermined number. The azimuth in which the object exists is detected using the high-resolution azimuth detection method in which the number is limited.

  In a sixth aspect based on the fifth aspect, the high-resolution azimuth detection method is a minimum norm method, a MUSIC (Multiple Signal Classification) method, a Capon method, or a Pisarenko method.

  According to a seventh invention, in the first invention, a directivity changing unit is provided that directs a null point of the directivity of the receiving antenna toward the direction of the object detected by the received signal processing unit.

  In an eighth aspect based on the seventh aspect, the reception antenna has two or more first predetermined number of antenna elements, and each received signal is received via the first predetermined number of antenna elements. Weight adjustment means for adjusting at least one of the phase and amplitude of the signal, and the directivity changing means is connected to the direction of the object detected by the received signal processing means via the weight adjustment means. Turn the directional null point.

  In a ninth aspect based on the first aspect, the transmission antenna has a second predetermined number of antenna elements of two or more, and the transmission means receives the plurality of transmission signals having different radio wave characteristics from each other. A transmission signal generation unit to generate, a synthesis wave generation unit to generate a synthesis wave of the plurality of transmission signals generated by the transmission signal generation unit, and the combined wave via the second predetermined number of antenna elements. A combined wave transmission unit that changes the directivity of the beam based on the radio wave characteristics of the transmission signal of the combined wave generated by the generation unit.

  According to a tenth aspect, in the ninth aspect, the radio wave characteristic is a frequency, and the transmission signal generation unit generates the plurality of transmission signals having different frequencies, and the combined wave generation unit , A plurality of transmission signals from the transmission signal generation unit are combined to generate a combined wave, and the combined wave transmission unit changes the beam directivity based on the frequency of the transmission signal of the combined wave, and Transmitting via a second predetermined number of antenna elements.

  According to an eleventh aspect, in the tenth aspect, the second predetermined number of antenna elements form an array antenna, and the combined wave transmission unit connects adjacent antenna elements so that energization is possible. And the combined wave generation unit inputs the combined wave to one of the second predetermined number of antenna elements, and is input to the other antenna elements via the phase adjustment line. The

  In a twelfth aspect based on the tenth aspect, the second predetermined number of antenna elements form an array antenna, and the synthesized wave transmitting unit is adjacent to the frequency of the synthesized wave transmission signal. A variable phase shifter is provided that changes the phase difference of the transmission signal supplied to the antenna element.

  According to the first aspect of the invention, a plurality of transmission signals are generated, and each transmission signal is sent toward a different area. A reception signal corresponding to each of the plurality of transmission signals is received, and a direction in which an object exists is detected for each received reception signal. Therefore, it is possible to detect the orientations of many objects with high accuracy without increasing the number of receiving antennas.

  That is, since the azimuth in which an object exists is detected for each received signal, for example, when detecting the azimuth of an object by implementing a high-resolution angle measurement method using the MUSIC method, ( (Number of receiving antennas) -1) It is possible to detect the orientations of a number of objects corresponding to the number of antennas with high accuracy. Therefore, when areas where a plurality of transmission signals are transmitted do not overlap, the orientations of the number of objects corresponding to (number of transmission signals) times ((number of reception antennas) -1) at maximum are highly accurate. Can be detected.

  For example, when the number of transmission signals is three and the number of reception antennas is three, this corresponds to a maximum of ((number of reception antennas) -1 = 2) (number of transmission signals = 3) times. It is possible to detect the orientations of the six objects to be detected with high accuracy.

  Moreover, since the azimuth | direction in which an object exists is detected for every received received signal, it is not necessary to perform a complicated calculation. For example, if the number of transmission signals is three and the number of reception antennas is three, the MUSIC method performed when the number of reception antennas is three corresponds to the maximum number of transmission signals. Therefore, it is only necessary to repeat the process three times, so there is no need to perform complicated calculations.

  According to the second aspect, for each of the plurality of transmission signals, a corresponding reception signal is received, and it is determined whether or not an object exists in each of the regions corresponding to the plurality of transmission signals. The Then, the azimuth in which the object exists is detected only in the region where it is determined that the object exists. Therefore, it is possible to reduce the load of calculation processing such as the MUSIC method executed to detect the direction in which the object exists.

  That is, since the azimuth in which the object exists is detected only in the region where it is determined that the object exists, the arithmetic processing such as the MUSIC method corresponding to the region where it is determined that the object does not exist is omitted. .

  According to the third aspect, when the radar apparatus is mounted on a vehicle and it is determined that an object exists, it is determined whether or not the detected object may collide with the own vehicle. Is done. Only when it is determined that there is a possibility of collision, the direction in which the object exists is detected. Therefore, it is possible to further reduce the load of calculation processing such as the MUSIC method executed to detect the direction in which the object exists.

  That is, only when it is determined that an object exists and it is determined that there is a possibility of colliding with the object, the direction in which the object exists is detected. The arithmetic processing such as the MUSIC method corresponding to the area determined not to be performed is omitted. That is, arithmetic processing such as the MUSIC method corresponding to the area where it is determined that the object does not exist and the area where the object exists but is determined not to collide with the host vehicle is omitted. It is.

  According to the fourth aspect of the invention, the azimuth in which the object exists is detected using the high resolution azimuth detection method that detects the azimuth from which the received signal arrives with high resolution. Therefore, the orientation of many objects can be detected with high accuracy without increasing the number of receiving antennas.

  According to the fifth aspect of the invention, the receiving antenna has a first predetermined number of antenna elements of two or more, and a high-resolution azimuth detection method in which the number of azimuths that can be detected is limited by the first predetermined number ( For example, the orientation in which the object exists is detected using a minimum norm method, a MUSIC method, or the like. Therefore, even when the MUSIC method or the like, which is a high-resolution azimuth detection method in which the number of azimuths that can be detected is limited by the first predetermined number (= corresponding to the number of reception antennas), the reception antenna (here, Then, the direction of many objects can be detected with high accuracy without increasing the number of antenna elements.

  That is, when using a high-resolution azimuth detection method in which the number of azimuths that can be detected is limited by the number of reception antennas, such as the MUSIC method, in order to detect many objects as described above, It is necessary to increase the number of However, since the direction in which an object exists is detected for each received signal, the direction of many objects can be detected with high accuracy without increasing the number of reception antennas. That is, the effect of the present invention becomes more apparent when a high-resolution azimuth detection method, such as the MUSIC method, in which the number of azimuths that can be detected is limited by the number of receiving antennas.

  According to the sixth aspect of the invention, the high resolution azimuth detection method is a minimum norm method, a MUSIC (Multiple Signal Classification) method, a Capon method, or a Pisarenko method. The minimum norm method, the MUSIC method, the Capon method, and the Pisarenko method are high-resolution azimuth detection methods in which the number of azimuths that can be detected is limited by the number of reception antennas. Therefore, the effect of the present invention that the azimuths of many objects can be detected with high accuracy without increasing the number of receiving antennas becomes more apparent.

  According to the seventh aspect, the directivity null point of the receiving antenna is directed to the direction of the detected object. Therefore, the orientation of the object can be detected with higher accuracy.

  According to the eighth aspect of the invention, the receiving antenna has two or more first predetermined number of antenna elements. Then, at least one of the phase and the amplitude of each received signal received via the first predetermined number of antenna elements is adjusted, and the directional null point of the receiving antenna is located in the direction of the detected object. Directed. Therefore, the directivity null point of the receiving antenna can be accurately directed to the direction of the detected object.

  According to the ninth aspect, the transmitting antenna has two or more second predetermined number of antenna elements. Further, the plurality of transmission signals having different radio wave characteristics are generated. Then, a composite wave of the generated plurality of transmission signals is generated. Further, the directivity of the beam is changed based on the radio wave characteristics of the generated composite wave transmission signal, and the beam is transmitted through the second predetermined number of antenna elements. Accordingly, each of the plurality of transmission signals can be transmitted to different regions via the transmission antenna.

  That is, since the plurality of transmission signals having different radio wave characteristics are transmitted with the beam directivity changed based on the corresponding radio wave characteristics, the radio wave characteristics of the plurality of transmission signals are changed to appropriate characteristics. By setting to, each can be sent to a desired area.

  According to the tenth aspect, the plurality of transmission signals having different frequencies are generated. Then, a plurality of generated transmission signals are combined to generate a combined wave. Further, the directivity of the beam is changed based on the frequency of the transmission signal of the composite wave, and transmitted through the second predetermined number of antenna elements. Accordingly, each of the plurality of transmission signals can be transmitted to different regions via the transmission antenna.

  That is, since the plurality of transmission signals having different frequencies are transmitted with the beam directivity changed based on the corresponding frequencies, the frequencies of the plurality of transmission signals are set to appropriate values. As a result, it can be sent to a desired area.

  According to the eleventh aspect, the second predetermined number of antenna elements form an array antenna. In addition, adjacent antenna elements are connected to each other by a phase adjustment line so as to be energized. The synthesized wave is input to one of the second predetermined number of antenna elements, and is input to the other antenna element via the phase adjustment line. Therefore, by appropriately forming the line length of the phase adjustment line, the plurality of transmission signals can be transmitted toward a desired region with a simple configuration.

  According to the twelfth aspect, the second predetermined number of antenna elements form an array antenna. Further, the phase difference between the transmission signals supplied to the adjacent antenna elements is changed by the variable phase shifter according to the frequency of the transmission signal of the combined wave. Therefore, by appropriately setting the phase difference set in the variable phase shifter, the plurality of transmission signals can be transmitted toward desired regions, respectively.

The block diagram which shows an example of a structure of the radar apparatus concerning this invention The block diagram which shows an example of a structure of the transmission part shown in FIG. The top view which shows an example of the transmission signal sent from a transmission part (antenna element) The block diagram which shows an example of a structure of the receiving part shown in FIG. The top view which shows an example of directivity PA of the receiving part (receiving antenna) formed of the weight adjustment part Flow chart showing an example of the operation of the control unit (first half) Flow chart showing an example of the operation of the control unit (second half) The block diagram which shows another example of the structure of the transmission part shown in FIG. 1 different from FIG.

  Embodiments of a radar apparatus according to the present invention will be described below with reference to the drawings. The radar apparatus according to the present invention transmits a transmission signal via a transmission antenna, receives a reception signal via a reception antenna, and detects an object based on the transmission signal and the reception signal. In the present embodiment, a case will be described in which the radar apparatus is mounted on a vehicle VC (see FIGS. 3 and 5) and detects an object in front of the vehicle VC.

  FIG. 1 is a block diagram showing an example of the configuration of a radar apparatus 1 according to the present invention. The radar apparatus 1 includes a control unit 11, a transmission unit 12, and a reception unit 13. The control unit 11 controls the operation of the entire radar apparatus 1 and functionally includes a transmission instruction unit 111, an object determination unit 112, a collision determination unit 113, a reception signal processing unit 114, and a directivity change unit. 115. The transmission unit 12 (corresponding to a transmission antenna) transmits a transmission signal in accordance with an instruction from the control unit 11 (transmission instruction unit 111). The receiving unit 13 (corresponding to a receiving antenna) receives a received signal in accordance with an instruction from the control unit 11 (directivity changing unit 115 or the like).

  The control unit 11 causes a microcomputer disposed at a proper position of the control unit 11 to execute a control program stored in advance in a ROM (Read Only Memory) disposed at a proper position of the control unit 11. The microcomputer is functionally functioned as functional units such as a transmission instruction unit 111, an object determination unit 112, a collision determination unit 113, a reception signal processing unit 114, and a directivity change unit 115.

  The transmission instruction unit 111 (corresponding to a part of the transmission unit) is a functional unit that transmits a transmission signal via the transmission unit 12. Specifically, the transmission instruction unit 111 generates a plurality (here, three) of transmission signals via the transmission unit 12, and transmits each transmission signal to a transmission antenna (= transmission unit 12: FIG. 2 (see FIG. 3), which are different from each other (here, areas AR1 to AR3 (see FIG. 3)). Further, the transmission instruction unit 111 detects an object (for example, the objects TG3 and TG4: see FIG. 5) by the object judging unit 112, and determines that the object (here, the objects TG3 and TG4: see FIG. 5) is a collision. When it is determined by the unit 113 that there is a possibility of collision with the vehicle VC, a transmission signal is transmitted only in the region where the object is detected (here, the region AR3) (see FIG. 5).

  The object determination unit 112 (corresponding to the object determination unit) receives a corresponding reception signal via the reception unit 13 for each of the plurality (here, three) of transmission signals, and the plurality (here, the number of transmission signals). This is a functional unit that determines whether or not an object exists in each of the areas (here, areas AR1 to AR3 (see FIG. 3)) corresponding to three transmission signals. Specifically, the object determination unit 112 determines whether or not an object exists, for example, depending on whether or not a reflected wave from the object is received as a reception signal via the reception unit 13. In addition, the object determination unit 112 detects the relative position and the relative speed of the object with respect to the host vehicle VC based on the transmission signal transmitted via the transmission unit 12 and the reception signal received via the reception unit 13. To do.

  A collision determination unit 113 (corresponding to a collision determination unit) determines whether or not the detected object may collide with the host vehicle VC when the object determination unit 112 determines that an object exists. It is a functional part. Specifically, for example, the collision determination unit 113 may collide with the host vehicle VC based on the relative position and relative speed of the object detected by the object determination unit 112 with respect to the host vehicle VC. It is determined whether or not there is.

  The reception signal processing unit 114 (corresponding to the reception signal processing means) receives reception corresponding to each of the plurality (here, three) of transmission signals via a reception antenna (= reception unit 13: see FIG. 4). It is a functional unit that receives a signal and detects the direction in which an object exists for each received signal received. However, here, the received signal processing unit 114 is an area (for example, the area AR3: see FIG. 3) in which it is determined that the object is present by the object determination unit 112, and the area (here Then, only when it is determined that there is a possibility that an object (here, object TG3, TG4: see FIG. 3) existing in the area AR3: see FIG. 3 may collide with the host vehicle VC. , The direction in which the objects TG3 and TG4 (see FIG. 3) exist is detected.

  The reception signal processing unit 114 detects the direction in which the object exists by using a high-resolution direction detection method such as a MUSIC (Multiple Signal Classification) method for detecting the direction in which the reception signal arrives with high resolution. Here, the “high-resolution azimuth detection method” is a concept that indicates a general method for detecting the arriving direction of a received signal with high resolution based on the principle of Fourier transform, and includes a beamformer method, a minimum norm method, and MUSIC. Method, Capon method, Pisarenko method, ESPRIT (Estimation of Signal Parameters via Rotational Innovation Techniques) method and the like.

  However, here, the received signal processing unit 114 is capable of being detected by a first predetermined number N (here, three) which is the number of antenna elements 131 (see FIG. 4) included in a receiving antenna such as the MUSIC method. The direction in which an object exists is detected using a high-resolution direction detection method in which the number of objects is limited. Specifically, the minimum norm method, the MUSIC method, the Capon method, or the Pisarenko method is used as the high-resolution azimuth detection method. Here, a case where the reception signal processing unit 114 uses the MUSIC method as a high-resolution azimuth detection method will be described.

  Here, the principle of detecting the signal arrival direction (= direction in which an object exists) in the MUSIC method will be briefly described. First, a correlation matrix is created from the time series output data of each antenna element 131 (see FIG. 4) constituting the array antenna. Then, eigenvalues and eigenvectors of the created correlation matrix are calculated. Next, the magnitudes of these eigenvalues are discriminated and classified into eigenvectors belonging to the signal space and eigenvectors belonging to the noise space, and direction-of-arrival estimation is performed using the fact that they are orthogonal to each other. That is, when the eigenvector matrix belonging to the noise space is multiplied by the signal arrival direction vector in the denominator and the angle of the signal arrival direction is scanned, the value of the denominator becomes zero when the angle matches the actual signal signal arrival direction. A steep peak is obtained by approaching. The MUSIC method uses this action to estimate the direction of arrival of a signal.

  In this way, the reception signal processing unit 114 detects the azimuth in which the object exists using the high-resolution azimuth detection method (here, the MUSIC method) that detects the azimuth from which the reception signal arrives with high resolution. The direction of many objects can be detected with high accuracy without increasing the number of receiving antennas (here, the first predetermined number N).

  In the present embodiment, the case where the reception signal processing unit 114 uses the MUSIC method as the high-resolution azimuth detection method will be described, but the reception signal processing unit 114 may use another high-resolution azimuth detection method. For example, the received signal processing unit 114 may use a minimum norm method, a Capon method, or a Pisarenko method as a high-resolution azimuth detection method. Further, for example, the received signal processing unit 114 may use a beamformer method or an ESPRIT method as a high-resolution azimuth detection method.

  Here, when the received signal processing unit 114 uses a method in which the number of azimuths that can be detected is limited by the number of receiving antennas (here, the first predetermined number N), such as the MUSIC method, as the high-resolution azimuth detection method. In order to enable detection of many objects, it is necessary to increase the number of reception antennas (here, the first predetermined number N). However, since the direction in which the object exists is detected by the received signal processing unit 114 for each received signal (here, for each of the three areas AR1 to AR3 shown in FIG. 3), the number of receiving antennas is increased. Therefore, the orientation of many objects can be detected with high accuracy. That is, since the high-resolution azimuth detection method in which the number of azimuths that can be detected is limited by the number of receiving antennas, such as the MUSIC method, the effect of the present invention becomes more apparent.

  In the present embodiment, the case where the reception signal processing unit 114 uses the MUSIC method as the high-resolution azimuth detection method will be described. However, the reception signal processing unit 114 depends on the number of reception antennas (here, the first predetermined number N). A form using a high-resolution azimuth detection method in which the number of detectable azimuths is limited may be used. For example, the received signal processing unit 114 may use a minimum norm method, a Capon method, or a Pisarenko method.

  Further, the direction in which the object exists is detected only when the object determination unit 112 determines that the object exists and the collision determination unit 113 determines that there is a possibility of collision with the object. The arithmetic processing such as the MUSIC method corresponding to the areas determined to have no object that may collide (here, the areas AR1 and AR2: see FIG. 3) is omitted. That is, the area where the object is determined not to exist (here, the area AR2: see FIG. 3) and the area where the object exists but is determined not to collide with the host vehicle (here Then, the arithmetic processing such as the MUSIC method corresponding to the area AR1: see FIG. 3) is omitted. Therefore, it is possible to reduce the load of arithmetic processing such as the MUSIC method that is executed by the reception signal processing unit 114 to detect the azimuth in which the object exists.

  In the present embodiment, the reception signal processing unit 114 is limited to an area (here, the area AR3: see FIG. 3) where it is determined that an object is present and that the object is likely to collide with the object. Although the case where the direction in which the object exists is detected has been described, the reception signal processing unit 114 determines that the object exists, and the existence of the object is limited to the areas (here, areas AR1 and AR3: see FIG. 3). The form which detects the direction to perform may be sufficient. In this case, the process by the collision determination unit 113 (= determination process of whether or not there is a possibility of collision) can be omitted.

  The directivity changing unit 115 (corresponding to the directivity changing unit) is configured to connect the receiving antenna (here, three antenna elements 131) to the direction of the object detected by the received signal processing unit 114 via the receiving unit 13. This includes a directivity null point NP (see FIG. 5) of the array antenna (see FIG. 4). Specifically, a method of changing the directivity of the receiving antenna will be described later with reference to FIG.

  In this way, the directivity of the receiving antenna (here, an array antenna including three antenna elements 131: see FIG. 4) is directed to the direction of the object detected by the reception signal processing unit 114 by the directivity changing unit 115. Since the null point NP (see FIG. 5) is directed, the orientation of the object can be detected with higher accuracy.

  In this embodiment, a case where the directivity changing unit 115 directs the null point of the directivity of the receiving antenna to the direction of the object detected by the received signal processing unit 114 will be described. A configuration in which a point having good directivity of the receiving antenna is directed to the direction of the object detected by the processing unit 114 may be used.

  FIG. 2 is a block diagram illustrating an example of the configuration of the transmission unit 12 illustrated in FIG. As shown in the figure, the transmission unit 12 transmits a transmission signal in accordance with an instruction from the transmission instruction unit 111, and includes a transmission signal generation unit 121, a synthesized wave generation unit 122, a phase adjustment line 123, and an antenna element. 124 is provided.

  The transmission signal generation unit 121 generates a plurality (here, three) of transmission signals having different radio wave characteristics according to an instruction from the transmission instruction unit 111. The transmission signal generation units 121a, 121b, 121c. In addition, the transmission signal generation unit 121 outputs the generated transmission signal to the synthesized wave generation unit 122. Here, the radio wave characteristic is a frequency, and the transmission signal generators 121a, 121b, and 121c each generate a plurality (three in this case) of transmission signals having different frequencies f. For example, the transmission signal generation units 121a, 121b, and 121c generate transmission signals having frequencies f1 = 75.5 GHz, f2 = 76.0 GHz, and f3 = 76.5 GHz, respectively.

  However, when an instruction to send a transmission signal is received from the transmission instruction unit 111 only in an area (here, the area AR3) where an object determined to possibly collide with the vehicle VC is detected. In other words, the transmission signal generation unit 121 generates only a transmission signal having a frequency corresponding to the region.

  The synthesized wave generator 122 synthesizes a plurality of (three in this case) transmission signals having different frequencies f generated by the transmission signal generator 121 to generate a synthesized wave. In addition, the synthesized wave generation unit 122 outputs the generated synthesized wave to the terminal 123 a formed at one end of the phase adjustment line 123.

  The phase adjustment line 123 (corresponding to the composite wave transmission unit) changes the directivity of the beam EB based on the frequency of the transmission signal of the composite wave generated by the composite wave generation unit 122, and a second predetermined number M (here) Then, transmission is performed via five antenna elements 124. The phase adjustment line 123 is a line that connects adjacent antenna elements 124 so as to allow energization. As shown in the figure, the synthesized wave is input from the synthesized wave generator 122 to the terminal 123 a formed at one end of the phase adjustment line 123.

The combined wave input to the terminal 123a is input to the antenna element 124 at one end (right end in the figure) via the terminal 123a, and input to the other antenna element 124 via the phase adjustment line 123. . The phase adjustment line 123 delays the synthesized wave according to the line length L and the frequency f (wavelength λ), and sets the angle θ that defines the projection direction of the beam EB. The angle θ is an angle with respect to the plane on which the antenna elements 124 are arranged. Here, the phase adjustment line 123 is wired in a dielectric (not shown). The angle θ is obtained by the following equation (1).
sin θ = − (λ × L) / (λg × d) ± (n × λ) / d (1)
Where λg is the wavelength in the dielectric, d is the antenna interval, and n is an arbitrary natural number.

  As shown in the equation (1), since the angle θ is set according to the frequency f (wavelength λ), the synthesized wave input to the terminal 123a is determined by the equation (1) according to the frequency. Radiated in a direction. Here, since the composite wave includes transmission signals of a plurality of (here, three) frequencies f (for example, f1 = 75.5 GHz, f2 = 76.0 GHz, f3 = 76.5 GHz), Transmission signals are transmitted in directions corresponding to the frequencies f1, f2, and f3 (here, three directions θ1, θ2, and θ3: see FIG. 3).

  The antenna element 124 forms an array antenna and sends out a transmission signal input via the terminal 123a.

  In this way, the directivity of the beam EB is changed by the transmitter 12 based on the corresponding frequencies f1, f2, and f3 of a plurality of (here, three) transmission signals having different frequencies f. Therefore, the frequency (f1, f2, f3) and the line length L of a plurality (three in this case) of transmission signals are set to appropriate values, respectively, and transmitted to a desired area. be able to.

  In the present embodiment, a case where the transmission signal generation unit 121 generates a plurality of transmission signals having different frequencies f will be described. However, the transmission signal generation unit 121 has a plurality of transmission signals having different radio wave characteristics. Any form may be used. For example, the transmission signal generation unit 121 may generate a plurality of transmission signals having different spreading codes. However, in this case, it is necessary to provide a circuit or the like that changes the directivity of the beam EB in accordance with the spread code of the transmission signal, instead of the phase adjustment line 123.

  In addition, by appropriately forming the line length L of the phase adjustment line 123, the plurality of (here, three) transmission signals can be transmitted to desired regions with a simple configuration. . As will be described later with reference to FIG. 8, the transmission unit 12 changes the phase difference of the transmission signal supplied to the adjacent antenna element 124 according to the frequency f of the transmission signal instead of the phase adjustment line 123. The form provided with the variable phase shifter 126 to be used may be sufficient.

  FIG. 3 is a plan view illustrating an example of a transmission signal transmitted from the transmission unit 12 (antenna element 124). As shown in the figure, the radar apparatus 1 according to the present invention is arranged with the front (upper side in the figure) facing the center position in the width direction of the front portion of the vehicle VC. Then, transmission signals corresponding to the frequencies f1, f2, and f3 included in the synthesized wave are transmitted in the directions of the angles θ1, θ2, and θ3 determined by the above equation (1). Then, objects in the areas AR1, AR2, AR3 corresponding to the respective frequencies f1, f2, f3 are detected.

  Here, a case where two objects TG1 and TG2 and objects TG3 and TG4 exist in the area AR1 and the area AR3 will be described. As will be described later with reference to FIG. 4, since the number of antenna elements 131 constituting the receiving antenna (corresponding to the first predetermined number N) is three here, as shown in FIG. When there are four objects TG1 to TG4 in the detection areas AR1 to AR3, conventionally, the signal arrival direction (= the direction in which the object exists) cannot be detected by the MUSIC method or the like.

  However, as described above, in the radar apparatus 1 according to the present invention, as shown in FIG. 3, the transmission unit 12 transmits transmission signals of the frequencies f1, f2, and f3 to the areas AR1 to AR3, respectively, and the reception signal processing unit. 114 detects the azimuth in which the object exists for each received signal (= for each of the areas AR1 to AR3) corresponding to each of a plurality (three in this case) of transmission signals, so that four objects TG1 to TG4 are detected. Signal arrival direction (= direction in which an object exists) can be detected by the MUSIC method or the like.

  For example, first, the transmission instruction unit 111 transmits a transmission signal toward the area AR1, and the reception signal processing unit 114 determines the signal arrival directions of the objects TG1 and TG2 existing in the area AR1 (= direction in which the object exists). Detected by MUSIC method or the like. Next, the transmission instruction unit 111 transmits a transmission signal toward the area AR3, and the reception signal processing unit 114 determines the signal arrival directions (= direction in which the object is present) of the objects TG3 and TG4 existing in the area AR3. It is detected by law. In this way, the signal arrival directions (= direction in which the object exists) of the four objects TG1 to TG4 can be detected by the MUSIC method or the like.

  FIG. 4 is a block diagram showing an example of the configuration of the receiving unit 13 shown in FIG. As shown in the figure, the receiving unit 13 receives a reflected wave reflected by an object as a received signal, and outputs the received signal to the control unit 11 (the object determining unit 112, the received signal processing unit 114, etc.). An element 131, a weight adjustment unit 132, and an addition unit 133 are provided.

  The antenna element 131 is an element that constitutes a reception antenna that receives a reflected wave transmitted from the transmission unit 12 and reflected by an object as a reception signal, and here, a first predetermined number N (here, which constitutes an array antenna) Then, three antenna elements. A reception signal received by the antenna element 131 is output to the weight adjustment unit 132.

  The weight adjustment unit 132 (corresponding to the weight adjustment unit) is received via the first predetermined number N (three in this case) of antenna elements 131 in accordance with an instruction from the directivity changing unit 115 shown in FIG. This adjusts at least one of the phase and amplitude of each received signal. Specifically, for example, the weight adjustment unit 132 sets the first predetermined number N to direct the null point of the directivity of the receiving antenna (= receiving unit 13) toward the direction of the object detected by the received signal processing unit 114. The phase and amplitude of each received signal received through (here, three) antenna elements 131 are adjusted.

  The addition unit 133 adds the reception signals output via the weight adjustment unit 132 and outputs the addition result by the control unit 11 (the object determination unit 112 and the reception signal processing unit 114) illustrated in FIG.

  FIG. 5 is a plan view showing an example of the directivity PA of the receiving unit 13 (receiving antenna) formed by the weight adjusting unit 132. Here, the weight adjustment unit 132 is adjusted and formed so that the null point NP is directed to the direction (the direction of the arrow in the figure) of the objects TG3 and TG4 existing in the area AR3 detected by the reception signal processing unit 114. An example of directivity PA is shown.

  In other words, the weight adjustment unit 132 is adjusted to direct the null point NP to the orientations of the objects TG3 and TG4 existing in the area AR3 (the direction of the arrow in the drawing) according to the instruction from the directivity changing unit 115 shown in FIG. The The directivity PA of the receiving unit 13 is adjusted as the directivity having the null point NP in the direction of the objects TG3 and TG4 (the direction of the arrow in the figure).

  In this way, the null point NP of the directivity PA of the receiving antenna (= receiving unit 13) is directed to the orientation of the detected objects TG3 and TG4. Therefore, the object TG3 is oriented to the orientation of the detected objects TG3 and TG4. , Azimuth of TG4 can be detected with higher accuracy.

  In the present embodiment, a case where the directivity changing unit 115 directs the null point NP of the directivity PA of the receiving antenna (= receiving unit 13) to the orientations of the objects TG3 and TG5 detected by the received signal processing unit 114 will be described. However, the directivity changing unit 115 may have another directivity in which the orientations of the objects TG3 and TG5 can be detected with high accuracy. For example, the directivity changing unit 115 may change the direction of the objects TG3 and TG5 to have a good directivity.

  Further, the phase and amplitude of each received signal received via the antenna element 131 so that the weight adjustment unit 132 directs the null point NP to the orientations of the objects TG3 and TG4 (in the direction of the arrow in the figure) existing in the area AR3. Therefore, the null point NP of the directivity PA of the receiving antenna (= receiving unit 13) can be accurately directed to the orientations of the objects TG3 and TG4.

  6 and 7 are flowcharts showing an example of the operation of the radar apparatus 1 (mainly the control unit 11) according to the present invention. First, as illustrated in FIG. 6, a plurality of (here, three) transmission signals are transmitted from the transmission instruction unit 111 via the transmission unit 12, respectively, in areas AR1 to AR3 (see FIG. 3) that are different from each other. (Step S101). Next, the object determination unit 112 determines whether a reception signal is received (= whether an object exists) for each of the areas AR1 to AR3 (S103).

  If it is determined that the received signal is not received for all the areas AR1 to AR3 (see FIG. 3) (NO in S103), the process is returned to step S101, and the processes after step S101 are repeatedly executed. The When it is determined that there is an area AR in which the received signal is received (YES in S103), the object determining unit 112 detects an object that exists in the area AR (here, areas AR1 and AR3) from which the received signal is received. A relative distance and a relative speed with respect to TG (here, objects TG1 to TG4) are detected (S105).

  Next, the collision determination unit 113 determines whether or not there is a possibility of collision with the vehicle VC for each object TG based on the relative distance and relative speed detected in step S105 (S107). If it is determined that there is no possibility that all objects collide with the vehicle VC (NO in S107), the process is returned to step S101, and the processes after step S101 are repeatedly executed. When it is determined that there is a possibility that at least one object TG collides with the vehicle VC (YES in S107), the received signal processing unit 114 causes an object TG that may collide with the vehicle VC (here, An area AR (here, area AR3) in which TG3 and TG4) exist is specified (S109).

  Next, as shown in FIG. 7, the reception signal processing unit 114 selects one area AR (here, area AR3) among the areas AR identified in step S109 (S111). Next, the transmission instruction section 111 sends a transmission signal toward the area AR (here, area AR3) selected in step S111 (S113). Next, the reception signal processing unit 114 arrives the reflected wave (= received signal) from the object TG (here, objects TG3 and TG4) existing in the area AR (here, area AR3) identified in step S111. The direction is detected using the MUSIC method (S115). Then, the directivity changing unit 115 changes the directivity PA of the receiving unit 13 to direct the null point NP in the arrival direction detected in step S115 (S117).

  Next, a transmission signal is transmitted by the transmission instruction unit 111 toward the area AR (here, the area AR3) selected in step S111, and the reception signal received by the object determination unit 112 via the reception unit 13 is transmitted. Based on the above, the relative position and the relative speed of the object TG (here, the objects TG3 and TG4) with respect to the host vehicle VC are detected (S119). Next, the reception signal processing unit 114 determines whether or not all the areas AR identified in step S109 in FIG. 6 have been selected (S121). If it is determined that all the areas AR have been selected (YES in S121), the process is returned to step S101, and the processes after step S101 are repeatedly executed. If it is determined that there is an area AR that has not yet been selected (NO in S121), the process returns to step S111, and the processes after step S111 are repeatedly executed.

  FIG. 8 is a block diagram showing another example of the configuration of the transmission unit shown in FIG. 1 that is different from FIG. The transmission unit 12 ′ illustrated in the drawing is different from the transmission unit 12 illustrated in FIG. 2 in that an amplitude adjuster 125 and a variable phase shifter 126 are provided instead of the phase adjustment line 123. Therefore, here, for convenience, the amplitude adjuster 125 and the variable phase shifter 126 will be mainly described.

  The variable phase shifter 126 (corresponding to a part of the combined wave transmission unit) changes the directivity of the beam EB based on the frequency of the transmission signal of the combined wave generated by the combined wave generation unit 122, and the second predetermined number. Transmission is performed via M (here, 5) antenna elements 124. The variable phase shifter 126 changes the phase of the transmission signal supplied to each antenna element 124 based on the frequency f (here, frequencies f1, f2, and f3) included in the combined wave, and directs the beam EB. Change sex. This method is called a “frequency scanning method”.

  The amplitude adjuster 125 (corresponding to a part of the combined wave transmission unit) is an amplifier that amplifies the amplitude of each transmission signal output from the variable phase shifter 126 and supplies the amplified signal to the antenna element 124.

Here, the frequency scanning method will be described. A method of scanning by changing the directivity (= angle θ) of the beam EB transmitted from each antenna element 124 by changing the frequency f of the transmission signal (here, set to frequencies f1, f2, and f3). It is. The condition for directing the main lobe (= the best directivity range) of the array antenna (= transmitting unit 12 ′) shown in FIG. 8 to an angle θ is expressed by the following equation (2).
δk = 2π × f × (dk / c) × sin θ (2)
Here, δk: phase set in the k-th variable phase shifter 126 from the right, dk: distance from the reference point of each antenna element 124 (for example, the position of the antenna element 124 at the right end), c: speed of light, k: 1-5.

  As shown in the above equation (2), the angle θ depends on the frequency f of the transmission signal (here, frequencies f1, f2, and f3), the distance dk from the reference point of each antenna element 124, and the variable phase shifter 126. It is determined based on the set phase δk. Therefore, in order to direct the main lobe of the array antenna (= transmission unit 12 ′) shown in FIG. 8 to the desired angles θ1, θ2, θ3 (see FIG. 3), for each frequency f1, f2, f3 of the transmission signal, An appropriate phase δk may be set in the variable phase shifter 126.

  As described above, according to the radar apparatus 1 according to the present invention, since the azimuth in which the object TG exists is detected for each received signal, for example, a high-resolution angle measurement method using the MUSIC method is implemented. When the orientation of the object TG is detected, the orientations of a number of objects TG corresponding to ((the number of reception antennas) −1) or less can be detected with high accuracy for each reception signal. Therefore, when the areas AR (here, areas AR1 to AR3) where a plurality of (here, three) transmission signals are transmitted do not overlap, ((number of receiving antennas) -1) ( The direction of the number of objects TG corresponding to the number of transmission signals) can be detected with high accuracy.

  For example, when the number of transmission signals is three and the number of reception antennas is three, this corresponds to a maximum of ((number of reception antennas) -1 = 2) (number of transmission signals = 3) times. The orientations of the six objects TG can be detected with high accuracy.

  In addition, since the azimuth in which the object TG exists is detected for each received signal, there is no need to perform complicated calculations. For example, if the number of transmission signals is three and the number of reception antennas is three, the MUSIC method performed when the number of reception antennas is three corresponds to the maximum number of transmission signals. Therefore, it is only necessary to repeat the process three times, so there is no need to perform complicated calculations.

The radar apparatus 1 according to the present invention is not limited to the above embodiment, and may be the following form.
(A) In the present embodiment, the case where the radar apparatus 1 is mounted on the vehicle VC has been described. However, the radar apparatus 1 may be mounted on other vehicles (for example, airplanes, ships, etc.). It may be good or may be arranged in a building such as a building.

  (B) In the present embodiment, the case where the radar apparatus 1 detects an object in front of the vehicle VC has been described. However, the radar apparatus 1 may be configured to detect an object around the vehicle VC. . For example, the radar device 1 may be configured to detect an object behind the vehicle VC, or the radar device 1 may be configured to detect an object located on the side of the vehicle VC.

  (C) In the present embodiment, the case where the control unit 11 includes functional units such as the transmission instruction unit 111, the object determination unit 112, the collision determination unit 113, the reception signal processing unit 114, and the directivity change unit 115 has been described. However, at least one functional unit among the transmission instruction unit 111, the object determination unit 112, the collision determination unit 113, the reception signal processing unit 114, and the directivity change unit 115 is realized by hardware such as a circuit. But it ’s okay.

  The present invention can be applied to, for example, a radar apparatus that transmits a transmission signal and receives a reception signal, and detects an object based on the transmission signal and the reception signal. More specifically, the present invention can be applied to, for example, a radar apparatus mounted on a vehicle.

DESCRIPTION OF SYMBOLS 1 Radar apparatus 11 Control part 111 Transmission instruction | indication part (a part of transmission means)
112 Object determination unit (object determination means)
113 Collision judging unit (collision judging means)
114 Received signal processing unit (received signal processing means)
115 Directivity changing unit (directivity changing means)
12, 12 'transmitter (transmitting antenna)
121 Transmission Signal Generation Unit 122 Synthetic Wave Generation Unit 123 Phase Adjustment Line (Synthetic Wave Transmission Unit)
124 Antenna element 125 Amplitude adjuster (part of combined wave transmitter)
126 Variable phase shifter (part of synthesized wave transmitter)
13 Receiver (Receiving antenna)
131 Antenna element 132 Weight adjustment unit 133 Addition unit

Claims (12)

A radar apparatus that transmits a transmission signal and receives a reception signal, and detects an object based on the transmission signal and the reception signal,
A transmission means for generating a plurality of transmission signals and transmitting each transmission signal toward a different area;
A radar apparatus comprising: received signal processing means for receiving a received signal corresponding to each of the plurality of transmitted signals and detecting an azimuth in which an object exists for each received received signal. For each of the plurality of transmission signals, a corresponding reception signal is received, and an object determination unit that determines whether an object exists in each of the regions corresponding to the plurality of transmission signals,
The radar apparatus according to claim 1, wherein the reception signal processing unit detects the azimuth in which the object exists only in a region where the object determination unit determines that the object exists. The radar device is mounted on a vehicle,
A collision determination unit that determines whether or not the detected object may collide with the host vehicle when the object determination unit determines that an object exists;
The radar apparatus according to claim 2, wherein the reception signal processing unit detects the azimuth in which the object exists only when it is determined by the collision determination unit that there is a possibility of collision.   The radar apparatus according to claim 1, wherein the reception signal processing unit detects an azimuth in which the object exists by using a high resolution azimuth detection method for detecting an azimuth from which the reception signal arrives with high resolution. The receiving antenna has a first predetermined number of antenna elements of two or more,
The radar according to claim 4, wherein the received signal processing means detects the azimuth in which the object exists by using the high-resolution azimuth detection method in which the number of azimuths that can be detected is limited by the first predetermined number. apparatus.   The radar apparatus according to claim 5, wherein the high-resolution azimuth detection method is a minimum norm method, a MUSIC (Multiple Signal Classification) method, a Capon method, or a Pisarenko method.   The radar apparatus according to claim 1, further comprising directivity changing means for directing a null point of the directivity of the receiving antenna toward the direction of the object detected by the received signal processing means. The receiving antenna has a first predetermined number of antenna elements of two or more,
Weight adjustment means for adjusting at least one of the phase and amplitude of each received signal received via the first predetermined number of antenna elements,
The radar apparatus according to claim 7, wherein the directivity changing unit directs a null point of the directivity of the reception antenna toward the direction of the object detected by the reception signal processing unit via the weight adjustment unit. The transmission antenna has a second predetermined number of antenna elements of two or more,
The transmission means includes
A transmission signal generation unit that generates the plurality of transmission signals having different radio wave characteristics;
A combined wave generating unit that generates a combined wave of the plurality of transmission signals generated in the transmission signal generating unit;
A combined wave transmission unit that transmits the second wave by changing the directivity of the beam based on the radio wave characteristics of the transmission signal of the combined wave generated by the combined wave generation unit via the second predetermined number of antenna elements. The radar apparatus according to claim 1. The radio wave characteristic is a frequency,
The transmission signal generation unit generates the plurality of transmission signals having different frequencies,
The combined wave generation unit generates a combined wave by combining a plurality of transmission signals from the transmission signal generation unit,
The radar apparatus according to claim 9, wherein the combined wave transmission unit transmits a beam through the second predetermined number of antenna elements while changing a beam directivity based on a frequency of a transmission signal of the combined wave. The second predetermined number of antenna elements form an array antenna;
The combined wave transmission unit includes a phase adjustment line that connects adjacent antenna elements so that energization is possible,
The combined wave generation unit inputs the combined wave to one of the second predetermined number of antenna elements and inputs the other antenna elements via the phase adjustment line. Item 11. The radar device according to Item 10. The second predetermined number of antenna elements form an array antenna;
The radar apparatus according to claim 10, wherein the combined wave transmission unit includes a variable phase shifter that changes a phase difference between transmission signals supplied to adjacent antenna elements according to a frequency of a transmission signal of the combined wave.

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