WO2013124969A1 - Radar device - Google Patents

Abstract

A radar device comprising: a transmission antenna that switches between and transmits radar waves having phases in the vertical direction that are mutually offset; a reception antenna having an array antenna that receives reflected waves from an object that has reflected the radar waves; and a detection unit that detects the object, using the reception results of the reception antenna.

Description

Radar equipment

The present invention relates to a radar apparatus that detects an object using a result of receiving a reflected wave from an object that reflects the radar wave.

A radar device that detects an angle in the vertical direction of an object by arranging a plurality of element antennas arranged in the horizontal direction while being shifted from each other in the vertical direction is known (for example, see Patent Document 1).

FIG. 1 is a configuration diagram of a radar apparatus 10 disclosed in Patent Document 1. The radar apparatus 10 is connected to a reception antenna 1 having element antennas # 1 to # 8 that are alternately shifted in the vertical direction, a transmission antenna 2 that operates with an oscillator 3, and element antennas # 1 to # 8 and the oscillator 3. Mixer unit 4 having mixers 4-1 to 4-8, and signal processing for performing fast Fourier transform processing (FFT processing) and digital beam forming processing (DBF processing) on the beat signal generated by mixer unit 4 Part 5.

The signal processing unit 5 uses the result of DBF synthesis for the upper element antennas # 1, # 3, # 5, and # 7 and the result of DBF synthesis for the lower element antennas # 2, # 4, # 6, and # 8. Thus, the vertical angle of the object is calculated by the phase monopulse method.

Japanese Patent Laid-Open No. 11-287857

However, in the configuration shown in FIG. 1, since the lower element antenna is disposed between the adjacent upper element antennas, it is difficult to reduce the antenna interval between the adjacent upper element antennas (for example, the upper element antenna # 1). And the lower element antenna # 2 is arranged between # 3 and # 3). Similarly, since the upper element antenna is disposed between the adjacent lower element antennas, it is difficult to narrow the antenna interval between the adjacent lower element antennas.

1) As the antenna interval between adjacent element antennas is narrower, the detectable range of the angle in the left-right direction becomes wider, so it is not easy to widen the detectable range of the angle in the left-right direction with the configuration shown in FIG.

Therefore, an object of the present invention is to provide a radar apparatus that can detect an angle in the vertical direction of an object and can easily expand a detectable range of the angle in the horizontal direction.

In order to achieve the above object, the present invention provides:
A transmission antenna that switches and transmits radar waves whose vertical phases are shifted from each other;
A receiving antenna having an array antenna for receiving a reflected wave from an object reflecting the radar wave;
A radar apparatus comprising: a detection unit that detects the object using a reception result of the reception antenna.

According to the present invention, the vertical angle of the object can be detected, and the detectable range of the horizontal angle can be easily expanded.

1 is a configuration diagram of a radar apparatus disclosed in Patent Document 1. FIG. It is a block diagram of the radar apparatus which concerns on one Embodiment. It is an example of a phase adjustment circuit. It is an example of an angle spectrum. It is an example of an angle spectrum. It is an operation example of a radar apparatus. It is a block diagram of the radar apparatus which concerns on one Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a configuration diagram of the radar apparatus 20 according to the first embodiment. The radar device 20 is mounted on a vehicle and is of an FMCW (Frequency Modulated Continuous Wave) method that can detect the distance and relative speed between the host vehicle and a target object around the host vehicle (for example, an object such as a vehicle in front of the host vehicle). Radar device.

For example, when detecting a target ahead of the host vehicle, the radar device 20 is installed on the vehicle body so that the normal directions of the antenna surface of the transmission antenna 21 and the antenna surface of the reception antenna 22 coincide with the front-rear direction of the vehicle. It is good to be. In FIG. 2, the x-axis direction is parallel to the horizontal plane such as the road surface, the x-axis direction is parallel to the horizontal plane, and the y-axis direction is the left-right direction of the vehicle (vehicle width direction). The vertical direction of the vehicle is the z-axis direction.

The radar apparatus 20 includes an oscillator 23, a transmission antenna 21, a reception antenna 22, and an object detection unit 26.

The oscillator 23 is a transmission signal generation unit that generates a transmission signal Ss whose frequency continuously increases and decreases according to a modulation signal Sm of a triangular wave. The frequency band of the transmission signal Ss is, for example, a millimeter wave band or a microwave band. Further, the local signal L generated by the power distribution of the transmission signal Ss by the distributor is supplied to the mixer unit 24 of the object detection unit 26. The local signal L has the same frequency as the transmission signal Ss.

The transmission antenna 21 is a transmission unit that transmits a radar wave based on the transmission signal Ss modulated by the modulation signal Sm, and switches and transmits radar waves whose phases in the vertical direction are shifted from each other. The transmission antenna 21 includes an element antenna 33, a phase adjustment circuit 31 that adjusts the phase of a radar wave transmitted from the element antenna 33, and two feeding points 11 and 12 of the element antenna 33.

The transmission antenna 21 has, for example, a plurality of transmission channels in which the phases of radar waves transmitted from the common element antenna 33 are shifted from each other in the vertical direction, and transmits the radar waves by switching these transmission channels. In FIG. 2, a transmission channel 34 that transmits a radar wave from the element antenna 33 according to the transmission signal Ss supplied from the feeding point 11 via the phase adjustment circuit 31, and supplied from the feeding point 12 via the phase adjustment circuit 31. A transmission channel 35 that transmits a radar wave from the element antenna 33 according to the transmission signal Ss is illustrated.

The transmission signal Ss is selectively input to the feeding points 11 and 12 via the switch 50. The switch 50 is a switching unit that selectively switches the supply destination of the transmission signal Ss generated by the oscillator 23 to the feeding point 11 or 12 in accordance with the switching control signal supplied from the signal processing unit 25 of the object detection unit 26.

The element antenna 33 is connected to the two feeding points 11 and 12 via the phase adjustment circuit 31. The element antenna 33 includes, for example, a plurality of patch antennas 32 arranged vertically and horizontally as a radiating element that transmits a radar wave based on a transmission signal Ss selectively input to the feeding point 11 or 12. . Each patch antenna 32 is connected to two feeding points 11 and 12 via a phase adjustment circuit 31.

The phase adjustment circuit 31 has directivity by shifting the phase of the radar wave transmitted from the common element antenna 33 in the vertical direction depending on the feeding point to which the common transmission signal Ss supplied from the oscillator 23 is input. This is a possible phase adjustment unit without change. That is, the phase adjustment circuit 31 receives the phase of the radar wave transmitted from the element antenna 33 when the transmission signal Ss is input to the feeding point 11 and the element antenna 33 when the transmission signal Ss is input to the feeding point 12. The phase of the transmitted radar wave can be shifted in the vertical direction. By providing such a phase adjustment circuit 31 between the feeding points 11 and 12 and the element antenna 33, even if there is only one transmission antenna 21 (even if there is only one element antenna 33), the vertical direction The same effect is obtained as when radar waves are transmitted from two transmitting antennas whose positions are physically shifted from each other.

FIG. 3 is a specific example of a phase adjustment circuit that enables transmission of radio waves whose phases are shifted in the vertical direction from the element antenna. The phase adjustment circuit 54 is inserted between the three feeding points 51, 52, 53 and the element antenna 55. There may be a plurality of feeding points to which the modulated transmission signal is selectively input, and the number of radar waves having different vertical phases can be increased or decreased according to the number of feeding points. As a prior art document relating to such a phase adjustment circuit, for example, JP 2009-76986 A can be cited.

In FIG. 2, the receiving antenna 22 includes an array antenna 43 that receives a reflected wave that arrives when a radar wave transmitted from the element antenna 33 of the transmitting antenna 21 is reflected by an object (not shown). The receiving unit outputs a corresponding received signal. The receiving antenna 22 is arranged on the same plane as the transmitting antenna 21.

The receiving antenna 22 has an array antenna 43 including a plurality of element antennas A2 to An arranged in the left-right direction. The number of these element antennas may be arbitrary. Each of the element antennas A2 to An has a plurality of patch antennas 42 arranged in a line in the vertical direction. Each patch antenna 42 of the element antennas A2 to An is connected to a reception port for each of the element antennas A2 to An. For example, the reception port P2 is a feeding point connected to each patch antenna 42 of the element antenna A2. The same applies to the reception ports P3 to Pn. The phase adjustment circuit 41 and the reception port P1 will be described later.

The object detection unit 26 is a circuit that detects an object reflecting a radar wave transmitted from the transmission antenna 21 based on reception signals supplied from the array antenna 43 via the reception ports of the element antennas A2 to An. . The object detection unit 26 includes a mixer unit 24 and a signal processing unit 25.

The mixer unit 24 outputs a beat signal for each of the element antennas A2 to An by mixing the local signal L supplied from the oscillator 23 with a reception signal supplied from each reception port of each of the element antennas A2 to An. It has mixers M1 to Mn.

The signal processing unit 25 performs an FFT process on the beat signal supplied from the mixer unit 24, thereby detecting the frequency of the component at which the signal strength of the beat signal reaches a peak as the beat frequency. The signal processing unit 25 detects an object reflecting the radar wave transmitted from the transmission antenna 21 using the detected beat frequency, and calculates a distance and a relative speed between the detected object and the radar apparatus 20.

Further, the signal processing unit 25 performs DBF processing on the beat signal supplied from the mixer unit 24, thereby calculating the angle (azimuth) in the left-right direction of the detected object by scanning the antenna beam in the left-right direction, and detecting the detection. The vertical angle (elevation angle) of the object is calculated by the phase monopulse method.

According to the radar apparatus 20 having such a configuration, it is possible to switch and transmit radar waves having different phases in the vertical direction from a single transmission antenna 21. Thereby, in order to generate a vertical phase shift on the receiving antenna 22 side, the element antennas A2 to An constituting the receiving antenna 22 can be arranged without being shifted in the vertical direction. That is, the vertical positions of the element antennas A2 to An can be made the same height. Therefore, since the antenna distance in the left-right direction between adjacent element antennas in the element antennas A2 to An can be easily reduced, the detectable range of the angle in the left-right direction can be easily expanded.

Also, the radar apparatus 20 includes a transmission antenna 21 that switches and transmits radar waves having different phases in the vertical direction depending on the feeding point. Thereby, the receiving antenna 22 can receive the reflected wave of the radar wave whose phase is shifted in the vertical direction. Therefore, the signal processing unit 25 of the object detection unit 26 can detect the vertical angle of the object based on the vertical phase shift received by the reception antenna 22.

For example, the signal processing unit 25 performs transmission control from the transmission antenna 21 by switching the feeding point to which the transmission signal Ss supplied from the oscillator 23 is input to the feeding point 11 or 12 by switching the switch 50. Shift the phase of the radar wave up and down.

The signal processing unit 25 acquires beat signals for the element antennas A2 to An as reception results obtained from the reception antenna 22 by radar waves transmitted from the transmission antenna 21 when the transmission signal Ss is input to the feeding point 11. . The signal processing unit 25 performs DBF synthesis on the beat signals for the element antennas A2 to An when power is supplied to the power supply point 11, thereby performing a left-right angle spectrum as shown in FIG. "Angle spectrum"). The signal processing unit 25 detects the azimuth θ1 at which the signal intensity of the first angle spectrum peaks, and detects the phase φ1 in the azimuth θ1.

Then, the signal processing unit 25 outputs a beat signal for each of the element antennas A2 to An as a reception result obtained from the reception antenna 22 by the radar wave transmitted from the transmission antenna 21 when the transmission signal Ss is input to the feeding point 12. get. The signal processing unit 25 performs DBF synthesis on the beat signals for each of the element antennas A2 to An when power is supplied to the power feeding point 12, thereby performing an angular spectrum in the horizontal direction as shown in FIG. "Angle spectrum"). The signal processing unit 25 detects the azimuth θ2 at which the signal intensity of the second angle spectrum peaks, and detects the phase φ2 in the azimuth θ2.

The signal processing unit 25 can detect the vertical angle of the detection object by the phase monopulse method based on the phase difference between the phase φ1 and the phase φ2 detected in this way.

However, since the feeding to the feeding point 11 or the feeding point 12 is switched with a time delay by the switch 50, there is a phase delay corresponding to the time when the feeding is switched between the feeding point 11 and the feeding point 12. The phase difference between the phase φ1 and the phase φ2 is included.

Therefore, in order to improve the detection accuracy of the angle in the vertical direction by canceling out such a phase delay, as shown in FIG. 2, the element antenna A2 constituting the array antenna 43 of the receiving antenna 22 Have a plurality of reception channels whose phases are shifted in the vertical direction. FIG. 2 shows a reception channel 44 for outputting a reception signal corresponding to the reflected wave received by the element antenna A2 from the reception port P2 via the phase adjustment circuit 41, and a reception signal corresponding to the reflection wave received by the element antenna A2. A reception channel 45 that outputs the signal from the reception port P1 via the phase adjustment circuit 41 is illustrated.

The reception port P1 is another feeding point of the element antenna A2, which is different from the reception port P2. Each patch antenna 42 of the element antenna A2 is connected to the reception ports P1 and P2 via the phase adjustment circuit 41.

The phase adjustment circuit 41 is a phase adjustment unit that can shift the vertical phase of the reflected wave received by the common element antenna A2. That is, the phase adjustment circuit 41 outputs the phase of the reception signal output from the reception port P1 according to the reflected wave received by the element antenna A2 and the output from the reception port P2 according to the reflected wave received by the element antenna A2. The phase of the received signal can be shifted in the vertical direction. The phase adjustment circuit 41 may be a circuit having the same phase adjustment characteristics as the phase adjustment circuit 31 of the transmission antenna 21 and may be the same circuit as the circuit illustrated in FIG.

The phase adjustment circuit 41 allows the reception channel 45 to shift the phase of the reflected wave received from the reception channel 44 in a direction to return the vertical phase shift of the radar wave transmitted from the transmission antenna 21. At this time, the phase adjustment circuit 41 shifts the phase of the reflected wave received by the reception channel 45 from the phase of the reflected wave received by the reception channel 44 by the same amount as the phase shift in the vertical direction of the radar wave. Adjust it. Thereby, the phase lag corresponding to the switching time of the switch 50 is canceled, and the phase difference between the phase φ1 and the phase φ2 can be accurately corrected.

FIG. 6 is a diagram illustrating an operation example of the radar apparatus 20 of FIG.

In step S <b> 11, the signal processing unit 25 switches the supply destination of the transmission signal Ss output from the oscillator 23 to the feeding point 11 by using the switch 50, and the transmission antenna 21 transmits to the feeding point 11 through the switch 50. A radar wave is transmitted according to the signal Ss.

In step S13, the signal processing unit 25 stores the azimuth θ1 and the phase φ1 measured using the reception ports P2 to Pn in the memory 27. For example, the signal processing unit 25 performs an FFT process on the beat signal obtained for each of the reception ports P1 to Pn for each of the reception ports P1 to Pn, so that the frequency spectrum for each of the reception ports P1 to Pn (hereinafter referred to as “first frequency”). Spectrum)). Then, the signal processing unit 25 performs a peak search of the signal intensity for the first frequency spectrum, and detects the frequency (beat frequency) and phase when the signal intensity is a peak for each of the reception ports P1 to Pn. The signal processing unit 25 performs DBF synthesis on the beat signals obtained from the reception ports P2 to Pn for each beat frequency detected based on the first frequency spectrum, so that the first angular spectrum illustrated in FIG. To get. The signal processing unit 25 detects the azimuth θ1 at which the signal intensity of the first angle spectrum peaks, and detects the phase φ1 in the azimuth θ1.

In step S15, the signal processing unit 25 stores the phase Φ1 measured using the reception port P2 in the memory 27. That is, the signal processing unit 25 stores the phase at the peak detected based on the frequency spectrum of the reception port P2 in the first frequency spectrum in step S13 in the memory 27 as the phase Φ1.

In step S <b> 17, the signal processing unit 25 switches the supply destination of the transmission signal Ss output from the oscillator 23 to the feeding point 12 by the switch 50, and the transmission antenna 21 transmits to the feeding point 12 through the switch 50. A radar wave is transmitted according to the signal Ss.

In step S19, the signal processing unit 25 stores the azimuth θ2 and the phase φ2 measured using the reception ports P2 to Pn in the memory 27. For example, the signal processing unit 25 performs FFT processing on the beat signal obtained for each of the reception ports P1 to Pn for each of the reception ports P1 to Pn, so that the frequency spectrum for each of the reception ports P1 to Pn (hereinafter referred to as “second frequency”). Spectrum)). Then, the signal processing unit 25 performs a peak search of the signal intensity for the second frequency spectrum, and detects a frequency (beat frequency) and a phase when the signal intensity is a peak for each of the reception ports P1 to Pn. The signal processing unit 25 performs DBF synthesis on the beat signals obtained from the reception ports P2 to Pn for each beat frequency detected based on the second frequency spectrum, thereby performing the second angular spectrum illustrated in FIG. To get. The signal processing unit 25 detects the azimuth θ2 at which the signal intensity of the second angle spectrum peaks, and detects the phase φ2 in the azimuth θ2.

In step S21, the signal processing unit 25 stores the phase Φ2 measured using the reception port P1 in the memory 27. That is, the signal processing unit 25 stores, in the memory 27, the phase at the peak detected based on the frequency spectrum of the reception port P1 in the second frequency spectrum in Step S19 as the phase Φ2.

In step S23, the signal processing unit 25 extracts detection objects having the same distance, the same speed, and the same direction. For example, the signal processing unit 25 uses the beat frequency detected based on the first frequency spectrum to calculate the distance and relative velocity of the detected object in the azimuth θ1 according to a well-known arithmetic expression, and generates the second frequency spectrum. Using the beat frequency detected on the basis, the distance and relative speed of the detected object in the azimuth θ2 are calculated according to a well-known arithmetic expression. The signal processing unit 25 extracts detection objects having the same distance, the same speed, and the same direction based on both the calculation results.

In step S25, the signal processing unit 25 subtracts the phase Φ1 stored in the memory 27 in step S15 from the phase Φ2 stored in the memory 27 in step S21 in order to cancel the phase delay caused by the switching time of the switch 50. Thus, the phase difference ΔΦ is calculated.

In step S27, the signal processing unit 25 calculates elevation angle information such as an angle in the vertical direction of the detection object according to the following equation using ΔΦ, φ1, and φ2 by the phase monopulse method.

Here, η is the angle in the vertical direction, d is the distance in the vertical direction of the reception ports 1 and 2, and λ is the wavelength of the radar wave.

The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and the above-described embodiments can be combined with some or all of the other embodiments. Various modifications such as substitution can be added.

For example, in the above description, the configuration in which the phase adjustment circuit is provided only for one element antenna that constitutes the array antenna is shown, but at least one of the element antennas that constitute the array antenna may have a phase adjustment circuit. .

FIG. 7 is a configuration diagram of the radar apparatus 60 according to the second embodiment. A description of the same configuration as that of the above embodiment is omitted. The radar device 60 includes a transmission antenna 61 and a reception antenna 62.

The transmission antenna 61 does not have a phase adjustment circuit for shifting the phase of the radar wave in the vertical direction. The receiving antenna 62 has an array antenna including a plurality of element antennas B1 to Bn arranged in the left-right direction. The element antenna B1 has a phase adjustment circuit U1 that can shift the vertical phase of the reflected wave received by the element antenna B1. All of the other element antennas B2 to Bn have the same phase adjustment circuits U2 to Un. The patch antennas of the element antennas B2 to Bn are connected via reception ports R1 to Rn and Q1 to Qn.

The mixer unit 28 of the object detection unit 29 mixes the local signals supplied from the oscillator 23 with the reception signals supplied from the reception ports R1 to Rn and Q1 to Qn of the element antennas B1 to Bn. Mixers S1 to Sn and T1 to Tn for outputting beat signals for the antennas B1 to Bn are provided.

Therefore, the phase adjustment circuit U1 can generate a vertical phase difference between the reception signal output from the reception port Q1 and the reception signal output from the reception port R1. Therefore, the signal processing unit 25 can detect the vertical angle of the object detected by the element antenna B1 based on this phase difference by the phase monopulse method. The same applies to the other phase adjustment circuits U2 to Un. Therefore, the signal processor 25 can accurately detect the vertical angle of the detection object based on the phase difference between the reception ports of the element antennas B1 to Bn.

1, 22, 62 Reception antenna 2, 21, 61 Transmission antenna 3, 23 Oscillator 5, 25 Signal processing unit 4, 24, 28 Mixer unit 10, 20, 60 Radar device 11, 12, 51, 52, 53 Feed point 26 , 29 Object detection unit 27 Memory 31, 41, 54 Phase adjustment circuit 32, 42 Patch antenna 33, 55 Element antenna 34, 35 Transmission channel 43 Array antenna 44, 45 Reception channel 50 Switch A _* (* is a number) Element antenna P _* (* Is a number) Receive port

Claims (6)

1. A transmission antenna that switches and transmits radar waves whose vertical phases are shifted from each other;
   A receiving antenna having an array antenna for receiving a reflected wave from an object reflecting the radar wave;
   A radar apparatus comprising: a detection unit that detects the object using a reception result of the reception antenna.
2. The radar apparatus according to claim 1, wherein the transmission antenna has a plurality of transmission channels in which phases of radar waves to be transmitted are shifted in the vertical direction, and transmits the radar waves by switching the transmission channels.
3. The detection unit is configured to transmit the radar wave on the first transmission channel among the plurality of transmission channels and the radar wave on the second transmission channel among the plurality of transmission channels. The radar apparatus according to claim 2, wherein the object is detected using the reception result.
4. The radar apparatus according to any one of claims 1 to 3, wherein at least one of the element antennas constituting the array antenna has a plurality of reception channels in which phases of received reflected waves are shifted from each other in the vertical direction.
5. The first reception channel of the plurality of reception channels shifts the phase of the received reflected wave in a direction to return the phase shift of the radar wave relative to the second reception channel of the plurality of reception channels. The radar apparatus according to claim 4.
6. The detection unit detects an angle in the vertical direction of the object using a phase difference between the phase of the reflected wave received by the first reception channel and the phase of the reflected wave received by the second reception channel. The radar apparatus according to claim 5.

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