Vehicle radar systems

Abstract

A vehicle radar system according to one aspect of the present disclosure includes a first radar device (A), a second radar device (B1), and a third radar device (C1). The first radar device (A) transmits a first radar wave, the transmission time or frequency of which is different from the transmission time or frequency of the second radar wave transmitted by the second radar device (B1) and the third radar wave transmitted by the third radar device (C1). The second radar device (B1) transmits a second radar wave, the transmission polarization or transmission beam direction of which is different from the transmission polarization or transmission beam direction of the third radar wave transmitted by the third radar device.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This international application claims the benefit of priority from Japanese Patent Application No. 2019-202344 filed with the Japan Patent Office on November 7, 2019, and the entire contents of Japanese Patent Application No. 2019-202344 are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a vehicle radar system including three or more radar devices. Background Art

[0004] The sensor system described in Patent Document 1 below includes multiple radio wave sensors installed at an intersection. These sensors perform time-division or frequency-division transmission to suppress radio wave interference between the sensors. In time-division transmission, the sensors transmit radio waves at different times. In frequency-division transmission, the sensors transmit radio waves at different frequencies.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-203735

[0006] Radio interference between multiple sensors also poses a problem when multiple radar devices are installed on a vehicle. However, the inventors' detailed research has revealed that when a vehicle is equipped with three or more radar devices and uses time-division transmission, the observation time allocated to each radar device is shortened, narrowing the observation range. Furthermore, the inventors' detailed research has revealed that when a vehicle is equipped with three or more radar devices and uses frequency-division transmission, the frequency band allocated to each radar device is narrowed, reducing range resolution. Summary of the Invention

[0007] One aspect of the present disclosure is to obtain appropriate detection results while suppressing the occurrence of radio wave interference among three or more radar devices mounted on a vehicle.

[0008] A vehicle radar system according to one aspect of the present disclosure includes a first radar device, a second radar device, and a third radar device. The first radar device is mounted on a vehicle. The second radar device is mounted on a vehicle. The third radar device is mounted on a vehicle. The first radar device is configured to transmit a first radar wave at a different time or frequency than a second radar wave transmitted by the second radar device and a third radar wave transmitted by the third radar device. The second radar device is configured to transmit a second radar wave having a different transmission polarization or transmission beam direction than a third radar wave transmitted by the third radar device.

[0009] According to one aspect of the vehicle radar system disclosed herein, the transmission time or frequency of a first radar wave transmitted from a first radar device differs from the transmission time or frequency of a second radar wave transmitted from a second radar device and a third radar wave transmitted from a third radar device. Furthermore, the transmission polarization or transmission beam direction of the second radar wave differs from the transmission polarization or transmission beam direction of the third radar wave. This allows for the allocation of appropriate observation time and frequency bands to each radar device while suppressing radio interference between the first, second, and third radar devices. Consequently, it is possible to obtain appropriate detection results while suppressing radio interference between three or more radar devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a diagram showing the mounting position of a radar device included in a vehicle radar system.

[0011] Figure 2 This is a block diagram showing the configuration of each radar device.

[0012] Figure 3 This is a diagram showing the transmission timing and transmission polarization of the forward radar and the surrounding radar according to the first embodiment.

[0013] Figure 4 This is a diagram showing the transmission frequencies and transmission polarizations of the forward radar and the surrounding radar according to the second embodiment.

[0014] Figure 5 This is a diagram showing the transmission times and frequencies of the forward radar and the surrounding radar according to the third embodiment. DETAILED DESCRIPTION

[0015] Hereinafter, modes for implementing the present disclosure will be described with reference to the drawings.

[0016] (First embodiment)

[0017] <1. Structure>

[0018] First, refer to Figure 1 The configuration of the vehicle radar system 80 of this embodiment will be described. The vehicle radar system 80 includes a first radar device A, a second radar device B1, a third radar device C1, a fourth radar device B2, and a fifth radar device C2.

[0019] The first radar device A is a front radar, and the second radar device B1 , the third radar device C1 , the fourth radar device B2 , and the fifth radar device C2 are surrounding radars.

[0020] The first radar device A is mounted in the front center of the vehicle 50 (for example, in the center of the front bumper). The detection area of ​​the first radar device A is the front center area of ​​the vehicle 50.

[0021] The second radar device B1 is mounted on the left front side of the vehicle 50 (e.g., the left end of the front bumper). The detection area of ​​the second radar device B1 is the area in front of the left side of the vehicle 50. The third radar device C1 is mounted on the right front side of the vehicle 50 (e.g., the right end of the front bumper). The detection area of ​​the third radar device C1 is the area in front of the right side of the vehicle 50.

[0022] The fourth radar device B2 is mounted on the right rear side of the vehicle 50 (for example, at the right end of the rear bumper). The detection area of ​​the fourth radar device B2 is the area to the right rear of the vehicle 50. Specifically, the fourth radar device B2 is mounted on the vehicle 50 at a position diagonally opposite the mounting position of the second radar device B1. In other words, the fourth radar device B2 is mounted on the vehicle 50 near the position farthest from the second radar device B1. The physical distance between the second radar device B1 and the fourth radar device B2 suppresses interference between the second radar wave transmitted from the second radar device B1 and the fourth radar wave transmitted from the fourth radar device B2.

[0023] The fifth radar device C2 is mounted on the left rear side of the vehicle 50 (for example, at the left end of the rear bumper). The detection area of ​​the fifth radar device C2 is the area behind the left rear of the vehicle 50. Specifically, the fifth radar device C2 is mounted on the vehicle 50 at a position diagonally opposite the mounting position of the third radar device C1. In other words, the fifth radar device C2 is mounted on the vehicle 50 near the position farthest from the third radar device C1. The physical distance between the third and fifth radar devices C1 and C2 suppresses radio interference between the third radar wave transmitted from the third radar device C1 and the fifth radar wave transmitted from the fifth radar device C2.

[0024] Next, refer to Figure 2 The configurations of the first to fifth radar devices A, B1, B2, C1, and C2 will be described.

[0025] The first to fifth radar devices A, B1 , B2 , C1 , and C2 are millimeter-wave radars including a transmitter 21 , a transmitter antenna 22 , a receiver antenna 23 , a receiver 24 , and a processor 30 .

[0026] The processing unit 30 includes a CPU 31 and a memory 32 . The processing unit 30 sets the transmission time and frequency of the radar wave transmitted from the transmission antenna 22 , and outputs a control signal corresponding to the set transmission time and frequency to the transmission unit 21 .

[0027] Transmitter 21 includes a transmission circuit, generates a millimeter-wave radar signal based on a control signal input from processor 30, and supplies the signal to transmitting antenna 22. Transmitter 22 includes multiple antenna elements and radiates millimeter-wave radar waves based on the supplied radar signal.

[0028] The receiving antenna 23 includes multiple antenna elements and receives reflected waves generated by radar waves reflected by target objects, and outputs the reflected signals to the receiving unit 24. The receiving unit 24 includes a receiving circuit that generates a beat signal by mixing the reflected signals with the radar signal, and samples the generated beat signal to output a detection signal to the processing unit 30.

[0029] The processing unit 30 performs frequency analysis and other methods on the acquired detection signals to calculate the target object information. This target object information includes, for example, the distance from the vehicle 50 to the target object, the relative speed of the target object with respect to the vehicle 50, and the orientation of the target object with respect to the vehicle 50. The processing unit 30 then outputs the calculated target object information to, for example, a driving assistance device.

[0030] <2. Suppression of radio interference>

[0031] Next, refer to Figure 3 A method of suppressing radio wave interference among the first to fifth radar devices A, B1, B2, C1, and C2 will be described.

[0032] As described above, second radar device B1 and fourth radar device B2 are mounted on substantially diagonal lines of vehicle 50, with their detection areas facing approximately 180° in opposite directions. Therefore, even if the second radar wave transmitted from second radar device B1 and the fourth radar wave transmitted from fourth radar device B2 are identical in transmission timing, frequency, and polarization, radio interference between second radar device B1 and fourth radar device B2 can be suppressed.

[0033] Similarly, even if the transmission time, transmission frequency, and transmission polarization of the third radar wave transmitted from the third radar device C1 and the fifth radar wave transmitted from the fifth radar device C2 are made the same, radio wave interference between the third radar device C1 and the fifth radar device C2 can be suppressed.

[0034] Therefore, the second radar device B1 and the fourth radar device B2 are grouped together, and this group is called radar group B. Furthermore, the third radar device C1 and the fifth radar device C2 are grouped together, and this group is called radar group C. Furthermore, the parameters of the radar waves transmitted from each radar device are adjusted so that radio interference does not occur between the first radar device A, radar group B, and radar group C. Furthermore, the parameters of the second and fourth radar waves are set identically. The parameters of the third and fifth radar waves are also set identically. The parameters of each radar wave correspond to the transmission time, transmission frequency, and transmission polarization.

[0035] In this embodiment, the first to fifth radar devices A, B1, B2, C1, and C2 use a common transmission frequency, but use different transmission times and transmission polarizations. Specifically, Figure 3 As shown, first radar device A transmits the first radar wave at a different time than the second, third, fourth, and fifth radar waves transmitted from radar groups B and C. This prevents radio interference between first radar device A and radar groups B and C.

[0036] Furthermore, the transmission polarization of the second and fourth radar waves transmitted from each radar device in radar group B is orthogonal to the transmission polarization of the third and fifth radar waves transmitted from each radar device in radar group C. Specifically, the transmitting antenna 22 and receiving antenna 23 of the second radar device B1 and the fourth radar device B2 are designed with a polarization angle of 45°. Meanwhile, the transmitting antenna 22 and receiving antenna 23 of the third radar device C1 and the fifth radar device C2 are designed with a polarization angle of -45°. This effectively reduces the occurrence of radio interference between radar groups B and C.

[0037] Furthermore, while the most preferred angular difference between the polarization angles of radar group B and radar group C is 90°, it does not necessarily need to be 90° and can be close to 90°. The closer the angular difference between the polarization angles of radar group B and radar group C is to 90°, the greater the effect of suppressing radio interference can be achieved.

[0038] In addition, although in this embodiment, the transmitting antenna 22 and the receiving antenna 23 of the first radar device A are designed to have a polarization angle of 0°, they can also be designed to have the same polarization angle as the radar group B or the same polarization angle as the radar group C.

[0039] <3. Effect>

[0040] According to the first embodiment described above, the following effects can be obtained.

[0041] (1) The transmission timing of the first radar wave transmitted from the first radar device A is different from the transmission timing of the second, third, fourth, and fifth radar waves transmitted from each radar device of radar group B and radar group C. Furthermore, the transmission polarization of the second and fourth radar waves transmitted from each radar device of radar group B is different from the transmission polarization of the third and fifth radar waves transmitted from each radar device of radar group C. This allows for allocating appropriate observation time to each of the first to fifth radar devices A, B1, B2, C1, and C2 while suppressing the occurrence of radio wave interference between the first radar device A, radar group B, and radar group C.

[0042] (2) The second radar device B1 and the fourth radar device B2 included in the radar set B are mounted at opposite corners to each other in the vehicle 50. Therefore, even if the transmission time, transmission frequency, and transmission polarization of the second radar wave transmitted from the second radar device B1 and the fourth radar wave transmitted from the fourth radar device B2 are made the same, the occurrence of radio wave interference between the second radar device B1 and the fourth radar device B2 can be suppressed.

[0043] (3) The third radar device C1 and the fifth radar device C2 included in the radar group C are mounted at opposite corners to each other in the vehicle 50. Therefore, even if the transmission time, transmission frequency, and transmission polarization of the third radar wave transmitted from the third radar device C1 and the fifth radar wave transmitted from the fifth radar device C2 are made the same, the occurrence of radio wave interference between the third radar device C1 and the fifth radar device C2 can be suppressed.

[0044] (Second embodiment)

[0045] <1. Differences from the First Embodiment>

[0046] The basic structure of the second embodiment is the same as that of the first embodiment, so the description of the common structure is omitted and the description will focus on the differences. In addition, the same reference numerals as those in the first embodiment represent the same structure, and reference is made to the previous description.

[0047] In the first embodiment described above, the first to fifth radar devices A, B1, B2, C1, and C2 use a common transmission frequency, but different transmission times and transmission polarizations. In contrast, the second embodiment differs from the first embodiment in that the first to fifth radar devices A, B1, B2, C1, and C2 use a common transmission time, but different transmission frequencies and transmission polarizations.

[0048] Specifically, if Figure 4As shown, first radar device A transmits a first radar wave at a different transmission frequency from the second, third, fourth, and fifth radar waves transmitted from radar groups B and C. In this embodiment, the 76 GHz to 77 GHz frequency band is divided into two. First radar device A then transmits the first radar wave using the higher frequency band. Meanwhile, radar groups B and C transmit the second, third, fourth, and fifth radar waves using the lower frequency band.

[0049] Furthermore, similar to the first embodiment, the difference between the polarization angles of the radar group B and the polarization angles of the radar group C is designed to be 90°.

[0050] <2. Effect>

[0051] According to the second embodiment described above, in addition to the effects (2) and (3) of the first embodiment described above, the following effects can be obtained.

[0052] (4) The transmission frequency of the first radar wave transmitted from the first radar device A is different from the transmission frequencies of the second, third, fourth, and fifth radar waves transmitted from each radar device of radar group B and radar group C. Furthermore, the transmission polarization of the second and fourth radar waves transmitted from each radar device of radar group B is different from the transmission polarization of the third and fifth radar waves transmitted from each radar device of radar group C. This allows for the allocation of appropriate frequency bands to the first to fifth radar devices A, B1, B2, C1, and C2 while suppressing the occurrence of radio wave interference between the first radar device A, radar group B, and radar group C.

[0053] (Third embodiment)

[0054] <1. Differences from the First Embodiment>

[0055] The basic structure of the third embodiment is the same as that of the first embodiment, so the description of the common structure is omitted and the description will be focused on the differences. In addition, the same reference numerals as those in the first embodiment represent the same structure, and reference is made to the previous description.

[0056] In the first embodiment described above, the first to fifth radar devices A, B1, B2, C1, and C2 use a common transmission frequency, but different transmission times and transmission polarizations. In contrast, the third embodiment differs from the first embodiment in that the first to fifth radar devices A, B1, B2, C1, and C2 use a common transmission polarization, but different transmission times and transmission frequencies.

[0057] In this embodiment, the first to fifth radar devices A, B1, B2, C1, and C2 each transmit two types of radar waves: long-range radar waves W1 and short-range radar waves W2. Specifically, the first, second, third, fourth, and fifth radar waves each include long-range radar waves W1 and short-range radar waves W2. The long-range radar waves W1 have a longer transmission time than the short-range radar waves W2. The short-range radar waves W2 have a wider frequency band than the long-range radar waves W1. Specifically, the long-range radar waves W1 are used to measure the distance from vehicle 50, while the short-range radar waves W2 are used to measure the vicinity of vehicle 50 with higher range resolution.

[0058] In this embodiment, if Figure 5 As shown, similarly to the first embodiment, the transmission time of the first radar wave of the first radar device A is set to a time different from the transmission time of the second radar wave, the third radar wave, the fourth radar wave, and the fifth radar wave of the radar group B and the radar group C.

[0059] Radar groups B and C then split the 76 GHz to 77 GHz frequency band into two and simultaneously transmit long-range radar waves W1 in different frequency bands. Subsequently, radar groups B and C transmit short-range radar waves W2 at different transmission times. The frequency band of radar group B's short-range radar waves W2 overlaps with the frequency band of radar group C's short-range radar waves W2.

[0060] <2. Effect>

[0061] According to the third embodiment described above, in addition to the effects (2) and (3) of the first embodiment described above, the following effects can be obtained.

[0062] (5) The transmission time of the first radar wave transmitted from the first radar device A is different from the transmission time of the second radar wave, third radar wave, fourth radar wave, and fifth radar wave transmitted from each radar device of radar group B and radar group C. Furthermore, the transmission frequency or transmission time of the second radar wave and fourth radar wave transmitted from each radar device of radar group B is different from the transmission frequency or transmission time of the third radar wave and fifth radar wave transmitted from each radar device of radar group C. This makes it possible to suppress the occurrence of radio wave interference between the first radar device A, radar group B, and radar group C while allocating appropriate transmission times and frequency bands to the first to fifth radar devices A, B1, B2, C1, and C2.

[0063] (Other Embodiments)

[0064] As mentioned above, although the form for implementing this disclosure was described, this disclosure is not limited to the above-mentioned embodiment, and can be implemented with various modifications.

[0065] (a) In the above embodiment, the transmission timing, transmission frequency, and transmission polarization of the first radar apparatus A, radar group B, and radar group C are adjusted to suppress the occurrence of radio interference between the first radar apparatus A, radar group B, and radar group C. However, the present disclosure is not limited to this. In addition to the transmission timing, transmission frequency, and transmission polarization, the direction of the transmission beam may also be adjusted to suppress the occurrence of radio interference between the first radar apparatus A, radar group B, and radar group C. For example, the transmission timing of the first radar apparatus A may be set to a different time from the transmission timing of radar groups B and radar group C, and the beam direction of radar group B may be set to a different direction from the beam direction of radar group C.

[0066] (b) While the vehicle radar system 80 in the above embodiment includes five radar devices, it may also include three or four radar devices. For example, the vehicle radar system 80 may include the first radar device A, the second radar device B1, and the third radar device C1, but not the fourth radar device B2 and the fifth radar device C2. Alternatively, the vehicle radar system 80 may include the first radar device A, the fourth radar device B2, and the fifth radar device C2, but not the second radar device B1 and the third radar device C1. Alternatively, the vehicle radar system 80 may include the second radar device B1, the third radar device C1, the fourth radar device B2, and the fifth radar device C2, but not the first radar device A.

[0067] (c) The vehicle radar system 80 and the method thereof described in the present disclosure may also be implemented by a dedicated computer provided by a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the vehicle radar system 80 and the method thereof described in the present disclosure may also be implemented by a dedicated computer provided by a processor composed of one or more dedicated hardware logic circuits. Alternatively, the vehicle radar system 80 and the method thereof described in the present disclosure may also be implemented by one or more dedicated computers composed of a combination of a processor and a memory programmed to execute one or more functions and a processor composed of one or more hardware logic circuits. In addition, a computer program may also be stored as an instruction executed by a computer in a non-migratable tangible recording medium that can be read by a computer. The method for implementing the functions of the various parts included in the vehicle radar system 80 does not necessarily need to include software, and all of its functions may be implemented using one or more hardware.

[0068] (d) It is also possible to implement multiple functions of a single component in the above-described embodiment by multiple components, or to implement a single function of a single component by multiple components. Furthermore, it is also possible to implement multiple functions of multiple components by a single component, or to implement a single function implemented by multiple components by a single component. Furthermore, it is also possible to omit a portion of the components of the above-described embodiment. Furthermore, it is also possible to add or replace at least a portion of the components of the above-described embodiment with the components of another above-described embodiment.

Claims

1. A vehicle radar system, wherein: have: The first radar device has the front of the vehicle as its detection range; The second radar device has a detection range in the left oblique front of the vehicle; as well as The third radar device has the right front of the vehicle as its detection range. The first radar device, the second radar device, and the third radar device transmit radar waves at a common transmission frequency. The vehicle radar system alternately repeats a first period and a second period. During the first period, the first radar device transmits a first radar wave. During the second period, the third radar device transmits a third radar wave with a transmission polarization different from that of the first radar device, in parallel with the second radar device transmitting a second radar wave with a transmission polarization different from that of the first radar device.

2. A vehicle radar system, wherein: have: The first radar device has the front of the vehicle as its detection range; The second radar device has a detection range in the left oblique front of the vehicle; as well as The third radar device has the right front of the vehicle as its detection range. The first radar device, the second radar device, and the third radar device transmit radar waves with a common transmission polarization. The vehicle radar system alternately repeats a first period and a second period. During the first period, the first radar device transmits a first radar wave. During the second period, the third radar device transmits a third radar wave at a transmission frequency different from that of the first radar device and the second radar device, in parallel with the second radar device transmitting a second radar wave at a transmission frequency different from that of the first radar device.

3. The vehicle radar system according to claim 1 or 2, wherein: The vehicle radar system further includes a fourth radar device mounted on the vehicle. The fourth radar device is configured to transmit a fourth radar wave, wherein the transmission time, transmission frequency, and transmission polarization of the fourth radar wave are the same as the transmission time, transmission frequency, and transmission polarization of the second radar wave transmitted by the second radar device. The second radar device and the fourth radar device are mounted at opposite corners of the vehicle.

4. The vehicle radar system according to claim 1 or 2, wherein: The vehicle radar system further includes a fifth radar device mounted on the vehicle. The fifth radar device is configured to transmit a fifth radar wave, wherein the transmission time, transmission frequency, and transmission polarization of the fifth radar wave are the same as the transmission time, transmission frequency, and transmission polarization of the third radar wave transmitted by the third radar device. The third radar device and the fifth radar device are mounted at opposite corners of the vehicle.

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