JP2009276076A - Radar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radar device that detects with high sensitivity both of a body such as a pedestrian in the distance from a vehicle and a body such as the pedestrian in proximity to the vehicle. <P>SOLUTION: The radar device includes a transmission-reception antenna for horizontality which emits a directional beam having directivity to the horizontal direction within an elevation plane and a transmission-reception antenna for high elevation which emits a directional beam having directivity to a prescribed direction above the horizontality. Besides, the radar device includes a switching means which switches the antenna for emitting the directional beam over to either the transmission-reception antenna for horizontality or that for high elevation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radar apparatus, and more particularly to an on-vehicle radar apparatus used for detecting a pedestrian or the like.

2. Description of the Related Art Conventionally, a vehicle equipped with an in-vehicle radar such as a millimeter wave radar is known for preventing a vehicle collision accident (for example, Patent Document 1). In the vehicle millimeter wave radar disclosed in Patent Document 1, an antenna having an antenna beam width of about 4 ° is provided at a height of about 1 to 2 m from the ground surface, and the antenna beam center is −4 in a vertical plane. It is set at more than ° (from horizontal to down). When detecting pedestrians using such a millimeter wave radar, by setting the antenna beam width to about 4 ° as described above, objects other than pedestrians, such as signs and signboards, are detected. Thus, unnecessary operations can be reduced. Also, from the viewpoint of cost reduction or the like, those having a narrow elevation angle are advantageous.
JP 09-2111116 A

  However, the millimeter wave radar-equipped vehicle disclosed in Patent Document 1 as described above has the following problems. Since the said patent document 1 mainly assumes a construction vehicle, it is provided in the height of about 1-2 m from the ground surface as a mounting height of a millimeter wave radar. When this millimeter wave radar is applied to a general passenger car, it is conceivable that the onboard radar is mounted at a height of about 30 cm to 1 m from the ground surface. However, when attempting to detect pedestrians at this height, radio waves are mainly emitted only to the feet of the pedestrians under circumstances where the pedestrian is approaching the vehicle. That is, as shown in FIG. 19, since the beam width of the millimeter wave radar is as narrow as 4 °, radio waves can be irradiated to the whole body about distant pedestrians, and pedestrian detection can be performed by the reflected waves. In a situation where a pedestrian approaches the vehicle, radio waves are mainly irradiated only to the pedestrian's feet. In other words, the area that the radio wave hits is small, and the foot when walking is intense and the angle is not vertical, so the reflection of the radio wave is disturbed and a reflected wave with a stable intensity cannot be obtained. As a result, there is a problem that pedestrian detection becomes difficult.

  For example, even if a pedestrian 20 m ahead from the vehicle is detected, the detected pedestrian cannot be detected when the pedestrian approaches 10 m or less. You will lose sight. Therefore, when a pedestrian is 20 meters away, for example, in a situation where the pedestrian is within 10 meters and the risk of accident is higher, even though the process for preventing the occurrence of the accident is executed. However, there is a problem that the pedestrian cannot be detected and the processing for preventing the occurrence of the accident as described above is not executed.

  Therefore, an object of the present invention is to provide a radar apparatus that can detect both an object such as a pedestrian located far from the vehicle and an object such as a pedestrian close to the vehicle with high sensitivity.

  The present invention employs the following configuration in order to solve the above problems. The reference numerals in parentheses, supplementary explanations, and the like are examples of the correspondence with the embodiments described later in order to help understanding of the present invention, and do not limit the present invention.

  The first invention is a transmitting means (12) for radiating a directional beam having directivity in the horizontal direction within the elevation angle plane and a directional beam having directivity in a predetermined direction above the horizontal. And a receiving means (13) for receiving the reflected wave of the directional beam emitted by the transmitting means reflected by the object.

  According to 1st invention, a directional beam can be irradiated to the trunk | drum part of the pedestrian who adjoined the vehicle, and the stable reflected wave with high intensity | strength can be obtained. As a result, more accurate pedestrian detection is possible.

  In a second aspect based on the first aspect, the transmitting means includes a horizontal transmission antenna (14) having a directivity peak direction that is horizontal, and a directivity peak direction that is a predetermined direction above the horizontal. And high-elevation-angle transmitting antennas (15, 21). The receiving means receives the reflected wave of the directional beam emitted from the horizontal transmitting antenna and the reflected wave of the directional beam emitted from the high elevation angle transmitting antenna. And a high elevation angle receiving antenna (17, 22) for receiving. The radar apparatus further includes switching means (18) for switching the antenna that radiates the directional beam to one of the horizontal transmission antenna and the high elevation angle transmission antenna.

  According to the second invention, the same effect as in the first invention can be obtained by switching between the antenna whose directivity peak direction is the horizontal direction and the antenna whose direction is higher than the horizontal direction.

  In a third aspect based on the second aspect, the high-elevation-angle transmitting antenna has an antenna beam width of 4 ° and a directivity peak direction in any direction of 3 to 7 °.

  According to the third aspect of the present invention, the directional beam can be more reliably irradiated onto the trunk portion of the pedestrian approaching the vehicle.

  In a fourth aspect based on the second aspect, the high elevation angle transmission antenna has a wider beam width than the horizontal transmission antenna.

  In a fifth aspect based on the fourth aspect, the horizontal transmitting antenna has an antenna beam width of 4 ° and a directivity peak direction of 0 °, and the high elevation transmitting antenna has an antenna beam. The width is 10 ° and the directivity peak direction is 3 °.

  According to the fourth to fifth inventions, a directional beam can be more reliably irradiated to a pedestrian close to the vehicle, and a stronger reflected wave can be obtained.

  In a sixth aspect based on the first aspect, any one of the transmission or reception means includes a horizontal antenna whose directional peak direction is a horizontal direction, and a predetermined direction whose directional peak direction is higher than the horizontal direction. And a high elevation angle antenna. The other means includes a receiving antenna (22) having a sensitivity in a range in which both the antenna beam width of the horizontal antenna and the antenna beam width of the high elevation angle antenna are combined.

  According to the sixth aspect, the same effect as in the first aspect can be obtained with only one receiving antenna.

  According to a seventh invention, in any one of the second to sixth inventions, the radar apparatus includes a first detection means (18) for detecting an object using a horizontally transmitting / receiving antenna having sensitivity, and a first detection means. And a second detection means (18) for detecting the object by switching to a transmission / reception antenna having sensitivity at a high elevation angle by the switching means after detecting the object.

  According to the seventh aspect, a pedestrian in the vicinity of the vehicle can be detected more reliably.

  In an eighth aspect based on the seventh aspect, the second detection means detects the object with the first detection means, and then the transmission means for the high elevation angle and the reception antenna for the high elevation angle with the switching means, or the horizontal transmission antenna. And switching to the horizontal receiving antenna, and executing processing for detecting an object based on the received signals received by the horizontal receiving antenna and the high elevation receiving antenna.

  According to a ninth aspect, in the eighth aspect, the radar apparatus stores in advance characteristic data indicating characteristics of a reception signal reflected by a predetermined object and received by the horizontal reception antenna and the high elevation reception antenna. Data storage means (19) is further provided. In addition, the second detection means performs processing for detecting an object by comparing the reception signal received by the horizontal reception antenna and the high elevation reception antenna with the characteristic data.

  According to the eighth to ninth inventions, more accurate pedestrian detection is possible.

  In a tenth aspect based on the first aspect, at least one of the transmitting antenna and the receiving antenna has a directional beam having a directivity in the horizontal direction and a directivity having a directivity in a predetermined direction above the horizontal. A special directional beam having a directivity synthesized with the beam is emitted.

  According to the tenth aspect, the same effect as in the first aspect can be obtained without performing a switching process between a plurality of antennas.

  According to the present invention, it is possible to prevent omission of detection of the pedestrian even in a situation where the pedestrian is close to the vehicle.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited by this Example.

(First embodiment)
FIG. 1 is a block diagram showing a functional configuration of an in-vehicle radar device 10 according to the first embodiment of the present invention. In FIG. 1, the in-vehicle radar device 10 includes a radar main body unit 11, a transmission unit 12, and a reception unit 13. The radar main unit 11 includes a CPU 18 as a control unit and a memory 19 in which a program for executing processing as described later is stored. The radar main body 11 (more precisely, a CPU mounted on the radar main body 11, but hereinafter simply referred to as a radar main body) outputs a transmission signal to the transmission unit 12. Further, the radar main body 11 acquires a reception signal output from the reception unit 13. More specifically, a transmission wave is emitted from the transmission antenna 14 or 15 (described later) attached to the transmission unit 12 to the front of the vehicle by the output of the transmission signal, and is reflected by collision with an object (so-called back scattering). Wave) is received by a receiving antenna 16 or 17 (described later) attached to the receiving unit 13. Thereby, the radar main body 11 detects the distance and relative speed between the vehicle and the object. Further, the radar main unit 11 outputs a switching signal as will be described later to the transmission unit 12 and the reception unit 13.

  A first transmission antenna 14 and a second transmission antenna 15 are attached to the transmission unit 12. These antennas are typically millimeter wave transmission antennas, and emit transmission waves in accordance with transmission signals output from the radar main body 11. In addition, the width of the emitted directional beam is 4 ° (± 2 °; minus downward from the horizontal) for both the first transmission antenna 14 and the second transmission antenna 15. The first transmitting antenna 14 is attached to the vehicle such that the in-elevation in-plane directivity has a peak in the horizontal plane. On the other hand, the second transmitting antenna 15 is mounted so that the elevation angle in-plane directivity has a peak at an elevation angle of 5 °. And according to the switching signal output from the radar main-body part 11, it is comprised so that switching to any one antenna is possible. That is, the transmission wave based on the transmission signal output from the radar main body 11 is emitted from one of the first transmission antenna 14 and the second transmission antenna 15 according to the switching state. In other words, the transmission unit 12 has a function of switching the transmission antenna to be used to one of the first transmission antenna 14 and the second transmission antenna 15 in accordance with the switching signal from the radar main body unit 11. Yes.

  A first receiving antenna 16 and a second receiving antenna 17 are attached to the receiving unit 13. These antennas are typically millimeter wave receiving antennas and receive the reflected waves. Here, the first receiving antenna 16 corresponds to the first transmitting antenna 14 and receives a reflected wave which is emitted from the first transmitting antenna 14 and collides with an object and is reflected. Similarly, the second receiving antenna 17 receives a reflected wave that is emitted from the second transmitting antenna 15 and is reflected by colliding with an object. Therefore, the first receiving antenna 16 is provided in accordance with the horizontal angle of the first transmitting antenna, and the second receiving antenna 17 is provided in accordance with the horizontal angle of the second transmitting antenna 15. ing. Similarly to the transmission unit 12, the reception unit 13 selects one of the first reception antenna 16 and the second reception antenna 17 as the reception antenna to be used according to the switching signal output from the radar main body unit 11. It has a function of switching to one.

  Next, the principle and processing outline of the present invention will be described with reference to FIGS. FIG. 2 is a diagram schematically showing an irradiation range of directional beams emitted from the first and second transmission antennas. In FIG. 2, a directional beam 141 indicates a beam emitted from the first transmitting antenna 14 (hereinafter referred to as a first beam), and a directional beam 151 is a beam emitted from the second transmitting antenna 15 ( Hereinafter, the second beam) is shown. The first beam 141 has an elevation in-plane directivity such that the horizontal plane has a peak as described above. On the other hand, the second beam 151 has an elevation in-plane directivity such that an elevation angle of 5 ° has a peak.

  In the present embodiment, normally, the pedestrian detection process is executed using the first transmitting antenna 14 and the first receiving antenna 16 (hereinafter, both antennas are collectively referred to as a first antenna set). When a pedestrian is detected by the first antenna set and the pedestrian approaches the vehicle within a predetermined distance, the second transmitting antenna 15 and the second receiving antenna 17 (hereinafter, both antennas are combined and The pedestrian detection process using the second antenna set is executed. That is, the pedestrian detection process is executed using both the first antenna set and the second antenna set.

First, when pedestrian detection is performed with the first antenna set, assuming that the mounting height of the radar apparatus 10 is 0.5 m, the radio wave irradiation range 20 m ahead is
0.5m ± 20m x tan (2 °) = 0m to 1.2m
Thus, as shown in FIG. 3, it is possible to irradiate the transmission waves from the road surface to main parts such as cars and pedestrians. However, the radio wave irradiation range 10m ahead is
0.5 m ± 10 m × tan (2 °) = 0.15 m to 0.85 m
In the case of a pedestrian, as shown in FIG. 3, almost no transmission wave is irradiated on the trunk. Furthermore, in a close situation of 10 m or less, the transmission wave is almost irradiated only to the feet of the pedestrian. Since the foot has a small area to which the transmission wave is irradiated and moves while walking, the angle does not become vertical, so the transmission wave is not strongly reflected. Therefore, a stable reflected wave cannot be obtained.

Therefore, in the present embodiment, when a pedestrian is detected by the first antenna set and the pedestrian approaches within a predetermined distance, for example, within 10 m, the second antenna set is set as described above. A pedestrian detection process is performed while using together (refer FIG. 4). The radio wave irradiation range of the second transmitting antenna 15 is 10 m away,
0.5m + 10m x tan (3 °) to 0.5m + 10m x tan (7 °)
= 1.02m to 1.73m
Thus, the irradiation area from the knee of the pedestrian becomes larger than that of the first transmitting antenna 14. Also, considering the case of 2m ahead,
0.5m + 2m × tan (3 °) to 0.5m + 2m × tan (7 °)
= 0.60m to 0.75m
In this case as well, the irradiation area from the pedestrian's knee to the top can be made relatively large. That is, since a transmission wave can be irradiated to a portion with little movement even during walking, it is possible to acquire a reflected wave with higher intensity and stability. This enables more accurate pedestrian detection.

  Here, with respect to the second antenna set as described above, a supplementary explanation will be given regarding the point where the peak of the elevation angle in-plane directivity is 5 °. 5 to 8 are graphs showing the trajectory of the result of detecting a pedestrian walking and approaching from the front 10m ahead, assuming that the mounting height of the radar device is 45 cm. 5 shows that when the central elevation angle of the antenna (the elevation angle at which the directivity reaches a peak) is 0 deg (that is, horizontal), FIG. 6 shows a central elevation angle of 3 deg, FIG. 7 shows a central elevation angle of 6 deg, and FIG. The detection result when the elevation angle is set to 9 deg is shown. 5 to 8, the radar apparatus is in the position of the lateral position “0 m” and the distance “0 m”. Moreover, the black dot in each graph has shown that the pedestrian was detected. As shown in these figures, the detection frequency of pedestrians is higher when the central elevation angle is 3 deg (FIG. 6) or 6 deg (FIG. 7) than when the central elevation angle is 0 deg (FIG. 5). ing. However, when the central elevation angle is 9 deg (FIG. 8), the detection frequency of pedestrians is lower than when the central elevation angle is 3 deg or 6 deg. In other words, when the elevation angle is 9 degrees, the antenna is in an excessively upward state, and the transmitted transmission wave passes through the pedestrian's head. From such detection frequency characteristics, it is considered that a value between about 3 ° and 7 ° is preferable as the central elevation angle of the antenna (when the mounting height of the radar device is 45 cm). Therefore, in the present embodiment, the central elevation angle is set to 5 °, which is substantially the central value within this range. Note that the center elevation angle of the second antenna set may be appropriately adjusted to an angle with a high pedestrian detection frequency by performing experiments and simulations as appropriate according to the mounting height of the radar device.

  Next, a pedestrian detection process executed by the radar apparatus 10 will be described with reference to FIG. FIG. 9 is a flowchart showing an overall process of the pedestrian detection process executed by the in-vehicle radar device 10. Note that the processing loop of steps S1 to S12 shown in FIG. 9 is repeatedly executed every 1/30 seconds.

  In FIG. 9, first, the radar main body 11 outputs a switching signal to the first antenna set (step S1). That is, the radar main unit 11 outputs an instruction signal for switching the transmission antenna to be used to the first transmission antenna 14 to the transmission unit 12, and the reception antenna to be used to the reception unit 13 is the first reception antenna 16. An instruction signal for switching to is output. When the switching is completed, the radar main body 11 outputs a transmission signal to the first transmission antenna 14. As a result, a transmission wave is emitted from the first transmission antenna 14.

  Next, the radar main body 11 acquires a reception signal from the first reception antenna 16, and executes a pedestrian detection process based on the reception signal (step S2). In addition, since the technique detected based on such a received signal is well-known, description about a specific process is abbreviate | omitted here.

  Next, the radar main body 11 determines whether or not a pedestrian has been detected as a result of the pedestrian detection process in step S2 (step S3). If no pedestrian is detected as a result of the determination (NO in step S3), the radar main unit 11 returns to step S2 and repeats the process.

  On the other hand, when a pedestrian is detected (YES in step S3), the radar main unit 11 then determines the vehicle on which the radar device 10 is mounted and the detected pedestrian based on the received signal. Is calculated (step S4). In addition, since the technique which calculates the distance with a pedestrian based on a received signal is well-known, description about a specific process is abbreviate | omitted.

  Next, the radar main body 11 determines whether or not the distance calculated in step S4 is 10 m or less (step S5). If it is not less than 10 m as a result of the determination (NO in step S5), the radar main body 11 returns to step S2 and repeats the process.

  On the other hand, when it is determined that the distance is 10 m or less (YES in step S5), it is considered that a pedestrian is approaching the vehicle, so the radar main body 11 outputs a switching signal to the second antenna set. (Step S6). That is, the radar main unit 11 outputs an instruction signal for switching the transmission antenna to be used to the second transmission antenna 15 to the transmission unit 12, and the reception antenna to be used to the reception unit 13 is the second reception antenna 17. An instruction signal for switching to is output. Thereafter, the radar body 11 outputs a transmission signal to the second transmission antenna 15. As a result, a transmission wave is emitted from the second transmission antenna 15.

  Next, the radar main body 11 acquires a reception signal from the second reception antenna 17, and executes a pedestrian detection process based on the reception signal (step S7). The detection result is temporarily stored in the memory 19.

  Next, the radar main body 11 outputs a switching signal to the first antenna set (step S8). Since this process is the same as the process in step S1, description thereof will be omitted.

  Next, the radar main body 11 acquires a reception signal from the first reception antenna 16, and executes a pedestrian detection process based on the reception signal (step S9). Since this process is the same as the process in step S2, the description is omitted.

  Next, the radar main body 11 determines whether or not a pedestrian has been detected in any of the results of the pedestrian detection process in steps S7 and S9 (step S10). As a result of the determination, when a pedestrian has been detected in any of the detection processes described above (YES in step S10), the radar main unit 11 performs a predetermined process, for example, the driver's attention to the presence of the pedestrian. Processing to prevent accidents from occurring, such as processing to display the display and processing to improve the braking effectiveness (processing to increase the brake response speed) (hereinafter referred to as pedestrian warning processing) Execute. Thereafter, the radar body 11 returns to step S6 and repeats the process.

  On the other hand, as a result of the determination in step S10, when no pedestrian is detected in any of the pedestrian detection processes in steps S7 and S9 (NO in step S10), the pedestrian is not approaching. Since it is considered, the radar main body 11 executes a clear process which is a process for stopping / releasing the pedestrian warning process executed in step S11. Thereafter, the radar main body 11 returns to step S2 and repeats the process. The above processing is repeatedly executed until a processing end condition due to engine stop or the like occurs. Above, description of the pedestrian detection process performed by the radar apparatus 10 is complete | finished.

  As described above, in this embodiment, two antenna sets having different elevation angles of directivity peaks are provided, and when it is detected that a pedestrian is approaching the vehicle, these two antenna sets are used in combination. Perform pedestrian detection processing. Thereby, it becomes possible to prevent the detection failure of the pedestrian at the time of pedestrian approach.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. In the first embodiment described above, after detecting the approach of a pedestrian (a state in which the pedestrian is within 10 m from the vehicle), a pedestrian detection process using both the first antenna set and the second antenna set. Is running. On the other hand, in 2nd Embodiment, after the approach of a pedestrian is detected, a pedestrian detection process is performed only by the 3rd antenna set mentioned later.

  FIG. 10 is a block diagram showing a configuration of the in-vehicle radar device 20 according to the second embodiment. The in-vehicle radar device 20 according to the second embodiment is basically the same as the first embodiment described above, but instead of the second transmitting antenna 15 and the second receiving antenna 17, a third one is used. Transmission antenna 21 and third reception antenna 22. The directivity of the third transmission antenna 21 is different from that of the second transmission antenna 15. More specifically, the third transmitting antenna 21 is attached so that the width of the directional beam is 10 ° (−2 ° to + 8 °), and the elevation angle in-plane directivity is 3 ° at the peak. It has been. The third reception antenna 22 also corresponds to the third transmission antenna 21. That is, the in-plane elevation directivity of the third receiving antenna 22 is 10 ° together with the third transmitting antenna 21 in order to cover a necessary range. The value of 10 ° is a value that takes into consideration the range in which the detection frequency of pedestrians is considered to be good as described above with reference to FIGS. Hereinafter, both antennas are collectively referred to as a third antenna set. Further, in FIG. 10, the parts other than those relating to the third antenna set are the same as those in the first embodiment, and therefore, the same reference numerals are given and detailed description thereof is omitted.

  Next, an outline of processing in the second embodiment will be described. FIG. 11 is a diagram schematically illustrating the irradiation range of the antenna according to the second embodiment. In FIG. 11, a directional beam 211 is a directional beam emitted from the third transmitting antenna 21 (hereinafter referred to as a third beam). As shown in FIG. 11, the width of the third beam 211 is 10 °, which is wider than that of the first beam 141. Therefore, the linearity is lower than that of the first beam 141, and radio waves do not reach as far as the first beam 141, but the irradiation range of the transmission wave is wider than that of the first beam 141. . In such a configuration, a pedestrian detection process using the first antenna set is normally executed as in the first embodiment.

  After the pedestrian is detected in the first antenna set, if it is detected that the pedestrian approaches within a predetermined distance, the antenna set used for pedestrian detection is switched to the third antenna set. In the second embodiment, the pedestrian detection process is executed using only the third antenna set. As described above, the width of the third beam irradiated from the third transmitting antenna 21 is a wide angle of 10 °. Therefore, a wide irradiation range can be secured even for an object such as a pedestrian approaching the vehicle. That is, it becomes possible to irradiate the trunk part with a transmission wave even for a pedestrian who is quite close to the vehicle. As a result, it is possible to acquire a stable reflected wave having a high intensity, and sufficient pedestrian detection can be performed using only the third antenna set. Thereby, the number of detection processes for the detection process after approaching a pedestrian can be reduced as compared with the first embodiment, and the processing load on the radar main body 11 can be reduced.

  Next, details of the pedestrian detection process executed by the on-vehicle radar device 20 according to the second embodiment will be described. FIG. 12 is a flowchart showing a pedestrian detection process executed by the in-vehicle radar device 20. In FIG. 12, the pedestrian detection process in the second embodiment includes a process in which steps S8 and S9 are omitted from the processes in steps S1 to S12 described with reference to FIG. 9 in the first embodiment. Become. That is, it is a process that omits the process related to switching to the first antenna set after the approach of the pedestrian is detected. Further, the process of step S21 is executed instead of the process of step S10. In step S21, the radar main body 11 executes a process of determining whether or not a pedestrian has been detected as a result of the pedestrian detection process using the second antenna set in step S7. As a result of the determination, when a pedestrian is detected in the second antenna set (YES in step S21), the process of step S11, that is, the pedestrian warning process is executed. On the other hand, when no pedestrian is detected in the second antenna set (NO in step S21), it is considered that the pedestrian is not approaching. Therefore, in step S12, that is, in step S11. The pedestrian warning process that was being executed is stopped or canceled.

  As described above, the second embodiment has a configuration in which an antenna with a wide angle of elevation in the plane (third antenna set) and a narrow-angle antenna (first antenna set) are mounted. Then, usually, a pedestrian detection process is performed using a narrow-angle antenna, and after detecting the approach of a pedestrian, the pedestrian detection process is performed by switching to a wide-angle antenna. This eliminates the need to switch (use together) the two antennas in the processing after detecting the approach of a pedestrian, thereby reducing the processing load.

  In the second embodiment described above, after detecting the approach of a pedestrian, the pedestrian detection process is performed using only the third antenna set. The first antenna set may be used together as appropriate in order to be able to detect both. In this case, the detection process using the first antenna set may be performed at a frequency lower than the frequency (every 1/30 seconds) as in the first embodiment described above. Note that when the detection process is performed at the same frequency as in the first embodiment, this corresponds to a replacement of the second antenna set in the first embodiment with a third antenna set. In this case, it is advantageous in that a more reliable pedestrian detection is possible, and in the case where the detection process is performed with a frequency less than that in the first embodiment, it is advantageous in that the processing load can be reduced.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 13 is a diagram illustrating a configuration of the in-vehicle radar device 30 according to the third embodiment. As shown in FIG. 13, the on-vehicle radar device 30 according to the third embodiment omits one receiving antenna from the configuration of the on-vehicle radar device 20 according to the first embodiment or the second embodiment. Only one third receiving antenna 22 is configured.

  That is, in the third embodiment, a reflected wave based on a transmission wave emitted from the first transmission antenna 14, the second transmission antenna or the third transmission antenna 21 is used by using the third reception antenna 22. Receive. That is, an antenna capable of receiving a wide angle so as to cover the directional beam width of each of the first transmission antenna 14, the second transmission antenna 15, and the third transmission antenna 21 is required. A third receiving antenna 22 that covers all the beam widths of the two transmitting antennas is used.

  That is, based on the first embodiment described above, the first transmission antenna 14 and the second transmission antenna 15 and the beam widths of both transmission antennas (9 ° in total in the example of FIG. 2). In combination with the third receiving antenna 22 (with a beam width of 10 °). Considering the second embodiment, the combination of the first transmission antenna 14 and the third transmission antenna 21 and the third reception antenna 22 that can cover the beam widths of both transmission antennas. It becomes. In such a configuration, processing as described in the first embodiment or the second embodiment is executed. However, since the configuration has only one receiving antenna, processing for switching the receiving antenna is not performed.

  As described above, the third embodiment is configured to use only one receiving antenna that can cover the beam widths of two transmitting antennas. Thereby, the process concerning switching of a receiving antenna from the pedestrian detection process demonstrated in the said 1st Embodiment and 2nd Embodiment can be omitted. As a result, the functions described in the first and second embodiments can be realized while further reducing the processing load.

(Fourth embodiment)
Next, an on-vehicle radar device according to a fourth embodiment of the present invention will be described. The block diagram showing the functional configuration of this in-vehicle radar device is the same as that of the first embodiment (see FIG. 1). However, in the present embodiment, a program that is partially different from that of the first embodiment is stored in the memory of the radar main body 11, and the radar main body 11 executes the program so as to be different from that of the first embodiment. Realizes different functions.

  Next, an outline of processing of the in-vehicle radar device according to the fourth embodiment will be described. As described above, the configuration of the present embodiment is the same as that of the first embodiment, and uses two antenna sets having different elevation angle in-plane directivity peaks. Here, it is assumed that the directivity (amplitude change and phase change with respect to angle) of these two antenna sets is the same. In this case, the properties of the complex signal Sa, which is a received signal received using the first antenna set, and the complex signal Sb received using the second antenna set are different. That is, since the in-plane directivities of both antenna sets are different, even if the object collided with the transmission wave is the same object, the amplitude (signal strength) of the complex signals Sa and Sb depends on the elevation angle of the object. ) Ratio and phase difference are different. In the present embodiment, a pedestrian, a vehicle, and a peripheral structure such as a sign using such properties are detected. That is, pattern map data in which a pattern of differences in received signals (complex signals Sa and Sb) as described above is created in advance using an object that is assumed to be a pedestrian or the like, and detection processing during actual driving is performed. , The received signal and the pattern map data are compared to determine whether or not the pattern matches the recorded pattern, thereby detecting a pedestrian or the like. More specifically, an object assuming the pedestrian or the like is prepared in advance, and the received signal is acquired by changing the elevation angle of the object. FIG. 14 is a schematic diagram illustrating an example of a method for acquiring the received signal. In FIG. 14, a pedestrian 142 exists at a position away from the antenna 141 by a predetermined distance. From this state, the pedestrian 142 approaches toward the antenna 141 (the elevation angle of the object changes as the pedestrian moves). And the received signal in the process in which the said pedestrian approaches the antenna 142 is acquired, and the map (combination pattern of the amplitude ratio and phase difference at the time of detection) in which the amplitude ratio and the phase difference with respect to each elevation angle are recorded is used as pattern map data. Preliminarily stored in the memory 19 in the radar main body 11. For example, when the object is located at a 10 m point, information such as the phase difference and amplitude ratio of reflected waves between the first antenna set and the second antenna set is recorded as pattern map data. FIG. 15 is a schematic diagram showing an example of the pattern map. In FIG. 15, the horizontal axis (X axis) indicates the reception level of the first antenna set, and the vertical axis (Y axis) indicates the level of the second antenna set. In addition, an axis (Z axis) directed in the depth direction indicates a distance from the antenna 141 to the pedestrian 142 (that is, FIG. 15 shows a three-dimensional image). The level ratio between the distance and the first antenna set and the second antenna set is indicated by a level distribution 143. Data indicating such a graph is stored in the memory 19 as pattern map data. In other words, information indicating the characteristics of the received signal when a pedestrian or the like is detected is recorded in the pattern map data. Then, in the pedestrian detection process during actual vehicle travel, the received signal received by the first receiving antenna 16 and the second receiving antenna 17 is compared with the pattern map data, and matches the recorded pattern. By detecting whether or not, the detection including the elevation angle information of the pedestrian or the like is performed.

  Hereinafter, the details of the process according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 16 is a flowchart showing a pedestrian detection process according to the fourth embodiment. In FIG. 16, the processing from step S1 to step S6 and the processing of step S8 and steps S11 to S12 are the same as the processing described with reference to FIG. 9 in the first embodiment described above. Detailed description will be omitted, and processing different from that of the first embodiment will be mainly described.

  In FIG. 16, after the process of step S6, the radar main unit 11 acquires a received signal from the second receiving antenna 17 (step S41). Next, the radar main body 11 performs the process of step S8 described above to switch to the first antenna set, and acquires a reception signal from the first reception antenna 16 (step S42).

  Next, the radar main body 11 executes pattern comparison processing using the pattern map data as described above (step S43). That is, the radar main body 11 calculates the amplitude ratio and phase difference between the reception signal acquired from the second reception antenna 17 and the reception signal acquired from the first reception antenna 16. Next, it is determined whether or not the calculated combination of the amplitude ratio and phase difference matches any pattern recorded in the pattern map data.

  Next, the radar main body 11 determines whether or not the pattern recorded in the pattern map data matches the pattern indicated by the received signal as a result of the process of step S43 (step S44). As a result of the determination, when it is determined that the pattern matches the pattern (YES in step S44), the radar main unit 11 executes the process of step S11 (warning process) described above. On the other hand, when it is determined that the pattern does not match (NO in step S44), the radar main body 11 executes the process of step S12 described above (stopping or canceling the warning process). The above processing is repeatedly executed until a processing end condition due to engine stop or the like occurs. This is the end of the description of the detection process according to the fourth embodiment.

  As described above, in the fourth embodiment, after the pattern map data, which is data indicating the characteristics of the received signal at the time of detecting a pedestrian or the like, is created in advance and the proximity of the pedestrian or the like is detected, Detection is performed by comparing the characteristics of the received signal obtained using the two antenna sets with the characteristics recorded in the pattern map data. Thereby, for example, more accurate detection is possible by enriching the contents of the pattern map data.

(Fifth embodiment)
Next, an in-vehicle radar device according to a fifth embodiment of the present invention will be described. FIG. 17 is a diagram illustrating a configuration of an in-vehicle radar device 50 according to the fifth embodiment. As shown in FIG. 17, in the on-vehicle radar device 50 according to the fifth embodiment, each of the transmitting antenna and the receiving antenna has one configuration. In FIG. 17, the directivity of the fourth transmission antenna 51 is a combination of the directivities of the first transmission antenna 14 and the second transmission antenna 15 in the second embodiment described above. FIG. 18 is a diagram schematically showing a directional beam of the fourth transmission antenna 51. As shown in FIG. 18, the directional beam 511 of the fourth transmission antenna 51 has a shape that combines the directivities of the first transmission antenna 14 and the third transmission antenna 21. In other words, the fourth transmission antenna 51 is an antenna formed so that the directional beam has a shape as shown in FIG. The fourth receiving antenna 52 is configured to cover the synthesized directivity range. For the beam shaping, a conventionally known beam shaping method may be used. That is, it can be considered that directivity as shown in FIG. 18 is formed by giving different signal strengths and phases to each antenna element.

  Thus, in the fifth embodiment, a transmission antenna that is beam-shaped so as to have different directivities is used. This makes it possible to obtain the same effects as those of the first and second embodiments without performing a process for switching a plurality of antenna sets.

  The radar apparatus according to the present invention can detect both an object far from the vehicle and an object close to the vehicle more accurately, and is useful for an on-vehicle radar apparatus or the like.

The block diagram which showed the function structure of the vehicle-mounted radar apparatus 10 which concerns on the 1st Embodiment of this invention. The figure which showed typically the irradiation range of the directional beam emitted from the 1st and 2nd transmitting antenna The figure which showed typically the irradiation range of the directional beam emitted from a 1st transmission antenna The figure which showed typically the irradiation range of the directional beam emitted from the 1st and 2nd transmitting antenna Graph showing pedestrian detection results when the elevation angle is 0 ° Graph showing pedestrian detection results when the elevation angle is 3 ° Graph showing pedestrian detection results when the elevation angle is 6 ° Graph showing pedestrian detection results when the elevation angle is 9 ° The flowchart which shows the pedestrian detection process performed by the vehicle-mounted radar apparatus 10 The block diagram which showed the function structure of the vehicle-mounted radar apparatus 20 concerning 2nd Embodiment. The figure which showed typically the irradiation range of the antenna concerning 2nd Embodiment The flowchart which shows the pedestrian detection process performed by the vehicle-mounted radar apparatus 20 The block diagram which showed the function structure of the vehicle-mounted radar apparatus 30 concerning 3rd Embodiment The figure for demonstrating the pattern map used by 4th Embodiment The figure for demonstrating the pattern map used by 4th Embodiment Flowchart showing detection processing according to the fourth embodiment. The block diagram which showed the function structure of the vehicle-mounted radar apparatus 50 concerning 5th Embodiment The figure which showed the directional beam of the 4th transmitting antenna typically A diagram for explaining the irradiation range of a conventional millimeter wave radar

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Car-mounted radar apparatus 11 Radar main-body part 12 Transmitting part 13 Receiving part 14 1st transmitting antenna 15 2nd transmitting antenna 16 1st receiving antenna 17 2nd receiving antenna 18 CPU
19 Memory 20 On-vehicle radar device 21 Third transmission antenna 22 Third reception antenna 30 On-vehicle radar device 50 On-vehicle radar device 51 Fourth transmission antenna 52 Fourth reception antenna

Claims (10)

Transmitting means for emitting a directional beam having directivity in the horizontal direction within the elevation angle plane and a directional beam having directivity in a predetermined direction above the horizontal;
A radar apparatus comprising: a receiving unit configured to receive a reflected wave of a directional beam emitted by the transmitting unit reflected by an object. The transmission means includes
A horizontal transmission antenna whose directivity peak direction is the horizontal direction;
A high-elevation-angle transmitting antenna whose peak direction of directivity is a predetermined direction above the horizontal,
The receiving means includes
A horizontal receiving antenna for receiving a reflected wave of a directional beam radiated from the horizontal transmitting antenna;
A high elevation angle receiving antenna for receiving a reflected wave of a directional beam radiated from the high elevation angle transmitting antenna;
The radar device is
The radar apparatus according to claim 1, further comprising switching means for switching an antenna that emits a directional beam to one of the horizontal transmission antenna and the high elevation angle transmission antenna.   The radar apparatus according to claim 2, wherein the high-elevation-angle transmitting antenna has an antenna beam width of 4 ° and a directivity peak direction in any direction within a range of 3 to 7 °.   The radar apparatus according to claim 2, wherein the high-elevation-angle transmitting antenna has an antenna beam width wider than that of the horizontal transmitting antenna. The horizontal transmission antenna has an antenna beam width of 4 ° and a directivity peak direction of 0 °,
The radar apparatus according to claim 4, wherein the high-elevation-angle transmitting antenna has an antenna beam width of 10 ° and a directivity peak direction of 3 °. Either the transmission or reception means is
A horizontal antenna whose directivity peak direction is the horizontal direction;
A high elevation angle antenna having a predetermined direction in which a peak direction of directivity is above the horizontal,
2. The radar apparatus according to claim 1, wherein the other means includes an antenna having a sensitivity in a range in which both the antenna beam width of the horizontal antenna and the antenna beam width of the high elevation angle antenna are combined. The radar device is
First detecting means for detecting an object using a horizontally transmitting / receiving antenna having sensitivity;
7. The apparatus according to claim 2, further comprising: a second detection unit configured to detect the object by detecting the object by the first detection unit and then switching to a transmission / reception antenna having sensitivity at a high elevation angle by the switching unit. The radar device described in 1.   The second detecting means detects the object by the first detecting means, and then uses the switching means to detect the high elevation angle transmitting antenna and the high elevation angle receiving antenna, or the horizontal transmitting antenna and the horizontal receiving antenna. The radar apparatus according to claim 7, wherein the radar apparatus executes a process of switching and detecting an object based on reception signals received by the horizontal reception antenna and the high elevation reception antenna. The radar apparatus further includes characteristic data storage means for preliminarily storing characteristic data reflected by a predetermined object and indicating characteristics of a received signal received by the horizontal receiving antenna and the high elevation receiving antenna;
The radar apparatus according to claim 8, wherein the second detection unit performs a process of detecting the object by comparing a reception signal received by the horizontal reception antenna and a high elevation reception antenna with the characteristic data.   At least one of the transmitting antenna and the receiving antenna has directivity obtained by combining the directional beam having directivity in the horizontal direction and the directional beam having directivity in a predetermined direction above the horizontal. The radar apparatus according to claim 1, which emits a special directional beam.

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