Radar device

Abstract

To provide a radar device capable of suppressing the influence of radio waves reflected by a cover section without restricting the shape of the cover section.SOLUTION: The radar device that transmits and receives radio waves via a cover member B includes an antenna substrate 10, a phase-shifter, and a control circuit. The antenna substrate 10 is provided opposite a cover member and has an antenna plane 11 on which a transmitting antenna 70, which transmits radio waves toward the cover member, and a receiving antenna 80, which receives radio waves reflected by a target and passing through the cover member, are arranged. The phase-shifter is for changing the beam angle (the transmission direction of the radio waves transmitted by the antenna). The control circuit is for controlling the phase-shifter to adjust the beam angle. The antenna substrate is arranged such that the antenna plane is inclined relative to the vertical direction and is disposed at an angle that is not parallel to an antenna-opposing surface B1 of the cover member, the surface B1 facing the antenna plane. The control circuit adjusts the transmission direction so that a scanning angle θS approaches a radar angle θR.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a radar device. [Background technology]

[0002] Conventionally, there is known a radar device that is installed inside a vehicle bumper and has an antenna for transmitting and receiving radio waves arranged on the front surface of a circuit board (see, for example, Patent Document 1). When the radar device transmits and receives radio waves through the bumper as in the configuration described in Patent Document 1, the reflected waves reflected on the inner surface of the bumper may interfere with the transmitted radio waves, and further, multiple reflections may occur in which part of the transmitted radio waves is reflected multiple times between the inner surface of the bumper and the surface of the circuit board. This interference between the reflected waves and the transmitted radio waves and the occurrence of multiple reflections can cause a decrease in the detection performance of the radar device when detecting targets.

[0003] In order to suppress the occurrence of multiple reflections, the radar device described in Patent Document 1 tilts the bumper relative to the vertical direction and arranges the circuit board along the vertical direction, so that the inner surface of the bumper and the surface of the circuit board are not parallel to each other. This allows the radar device described in Patent Document 1 to suppress the effects of radio waves reflected by the bumper. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent No. 9859613 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as described in Patent Document 1, the configuration in which the influence of radio waves reflected by a cover portion that covers a radar device, such as a bumper, is suppressed by its shape is not preferable because the shape of the cover portion is limited.

[0006] Furthermore, in preparation for the future shift to BEVs (Battery Electric Vehicles), there is a growing need to mount radar devices on the underside of bumpers. In recent years, bumpers with a distinctive vertically steep shape at the front of the vehicle have been increasing. Therefore, if a circuit board is arranged vertically on a bumper with such a distinctive shape, the bumper and the circuit board will be arranged in a parallel state, which raises concerns that the impact of reflection from the bumper will be greater. Therefore, a new method for preventing reflection, different from the measure of tilting the bumper shape as described in Patent Document 1, is needed.

[0007] In view of the above, an object of the present disclosure is to provide a radar device that can suppress the influence of radio waves reflected by a cover portion without restricting the shape of the cover portion. [Means for solving the problem]

[0008] According to one aspect of the present disclosure, The radar device transmits and receives radio waves through the cover member (B), an antenna array substrate (10) provided opposite the cover member and having an antenna surface (11) on which a transmitting antenna array (70) that transmits radio waves toward the cover member and a receiving antenna array (80) that receives radio waves reflected by a target and passed through the cover member are arranged; a phase shifter (42) that changes the beam angle, which is the transmission direction of the radio waves transmitted by the transmitting antenna; a control circuit (20) for controlling the phase shifter to adjust the beam angle; the antenna array substrate is arranged such that the antenna surface is inclined with respect to the vertical direction and is not parallel to an antenna facing surface (B1) of the cover member that faces the antenna surface, The control circuit determines the angle between the direction perpendicular to the antenna surface and the transmission direction as the scan angle (θ S ), and the angle formed by the vertical direction and the antenna plane is the radar angle (θ R ), the transmission direction is adjusted so that the scan angle approaches the radar angle.

[0009] This allows the transmitting antenna array and receiving antenna array to be arrayed, the array substrate to be positioned at an angle relative to the cover member, and the beam angle to be controlled by a control circuit to shift the phase of each antenna array and emit radio waves, thereby reducing the effects of interference from waves reflected by the cover member.

[0010] Furthermore, even if a portion of the reflected waves from the radar device is reflected again by the antenna-facing surface of the cover member, the direction of travel of the reflected waves is shifted either vertically upward or downward relative to the horizontal. This reduces the likelihood of multiple reflections, in which the reflected waves are repeatedly reflected between the cover member and the radar device. Furthermore, the reflected waves reflected by the antenna-facing surface of the cover member do not simultaneously interfere with the transmitted and received waves of each antenna array, and can be physically dispersed outside the reception range of the radar device, thereby reducing the effects of the reflected waves from the cover member. Therefore, regardless of the shape of the cover member, the effects of multiple reflections can be reduced by tilting the antenna board of the radar device, and the effects of radio waves reflected by the cover member can be reduced without restricting the shape of the cover member.

[0011] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing a vehicle to which a radar device according to a first embodiment is applied. [Figure 2] 1 is a diagram showing a state in which a radar device according to a first embodiment is disposed inside a vehicle. [Figure 3] 1 is a schematic configuration diagram of a radar device according to a first embodiment. [Figure 4] FIG. 2 is a schematic configuration diagram illustrating an example of a transmitting antenna according to the first embodiment. [Figure 5]1 is a schematic configuration diagram illustrating an example of a receiving antenna according to a first embodiment. [Figure 6] FIG. 10 is a diagram showing a comparative radar device arranged parallel to a bumper. [Figure 7] FIG. 10 is a diagram showing a state in which the radar device and the bumper are arranged in parallel. [Figure 8] FIG. 10 is a diagram showing a state in which the radar device and the bumper are arranged so as not to be parallel to each other. [Figure 9] FIG. 1 is a diagram for defining bumper angle, radar angle, and scan angle. [Figure 10] 3A and 3B are diagrams for explaining a bumper angle, a radar angle, and a scan angle according to the first embodiment. [Figure 11] FIG. 3 is a diagram showing the signal strengths when the radar device according to the first embodiment is configured as the configuration of this embodiment and a comparative configuration. [Figure 12] FIG. 10 is a diagram showing verification results of signal strength for each reception angle when the radar device according to the first embodiment is configured as the configuration of this embodiment and a comparative configuration. [Figure 13] 5A to 5C are diagrams showing verification results of signal strength when the bumper angle and radar angle of the radar device according to the first embodiment are changed. [Figure 14] 5A to 5C are diagrams showing verification results of ripples and average signal strength when the bumper angle and radar angle of the radar device according to the first embodiment are changed. [Figure 15] 10 is a diagram showing the difference in reception intensity when a reflected wave is received from the front and when the reflected wave is received from an angle other than the front. FIG. [Figure 16] 1 is a diagram showing a state in which the body of a vehicle to which the radar device according to the first embodiment is applied is not inclined relative to the horizontal direction. [Figure 17] 1 is a diagram showing a state in which the body of a vehicle to which a radar device according to a first embodiment is applied is tilted with respect to the horizontal direction. [Figure 18] 10A and 10B are diagrams for explaining the scan angle when the body of the vehicle is tilted relative to the horizontal direction. [Figure 19] 10A and 10B are diagrams for explaining a bumper angle, a radar angle, and a scan angle according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are the same as or equivalent to those described in the preceding embodiments will be given the same reference numerals, and their description may be omitted. Furthermore, in the embodiments, when only some of the components are described, the components described in the preceding embodiments can be applied to the remaining components. The following embodiments can be partially combined with each other, even if not specifically stated, as long as there is no particular problem with the combination.

[0014] (First embodiment) This embodiment will be described with reference to FIGS. 1 to 18. In this embodiment, an example will be described in which a radar device 1 according to the present disclosure is applied to a vehicle C shown in FIG. 1. The radar device 1 is a millimeter-wave radar device that transmits radio waves toward targets such as other vehicles and stationary objects present around the vehicle C and receives radio waves reflected by the targets to acquire information about the targets, such as the distance to the targets, their positions, and their shapes. The radar device 1 is used, for example, to measure the distance and relative speed between the vehicle itself and a preceding vehicle in order to implement adaptive cruise control (i.e., ACC) or an automatic braking system. The vehicle C equipped with the radar device 1 according to this embodiment will be referred to as the vehicle itself hereinafter.

[0015] As shown in FIG. 2, the radar device 1 is mounted on the inside of a bumper B on the front side in the traveling direction of the host vehicle, i.e., on the rear side of the front bumper, facing the inner surface B1 of the bumper B. As shown by the dashed arrows in FIGS. 1 and 2, the radar device 1 transmits radio waves toward the front of the host vehicle and receives radio waves reflected by targets in front of the vehicle C, thereby transmitting and receiving radio waves via the bumper B to acquire information about targets present around the host vehicle. In this embodiment, an example will be described in which the radar device 1 is disposed inside the bumper B so as not to be directly exposed to the outside and is protected by the bumper B. The bumper B corresponds to a cover member. In FIG. 2, the radio waves transmitted by the radar device 1 are indicated by dotted hatching.

[0016] The radar device 1 may be attached to multiple locations, such as the front, rear, and sides of the vehicle. The cover member that covers the radar device 1 is not limited to the bumper B, and a wide variety of cover members may be used. This embodiment describes a radar device 1 that can obtain radar transmission and reception performance equivalent to that of an emblem or a dedicated resin cover, even when a bumper B is used, which has poor radar transmission and reception performance, such as reflection and transmission characteristics, compared to a conventional emblem or dedicated resin cover that easily transmits radio waves transmitted by the radar device 1.

[0017] 1 etc., the configuration of the radar device 1 will be described below by referring to the traveling direction of the host vehicle, i.e., the fore-and-aft direction of the host vehicle, as the vehicle fore-and-aft direction D1, the up-and-down direction of the host vehicle, i.e., the vertical direction, as the vehicle up-and-down direction D2, and the left-and-right direction of the host vehicle, i.e., the vehicle width direction, as the vehicle left-and-right direction D3. The front in the vehicle fore-and-aft direction D1 will be referred to as the vehicle front D1a, the rear in the vehicle fore-and-aft direction D1 will be referred to as the vehicle rear D1b, the upper side in the vehicle up-and-down direction D2 will be referred to as the vehicle upper D2a, and the lower side in the vehicle up-and-down direction D2 will be referred to as the vehicle lower D2b. The vehicle lower D2b is the downward direction in the direction of gravity.

[0018] The radar device 1 of this embodiment is disposed on the rear side of the bumper B so as to face the bumper B. Furthermore, as shown in FIG. 2, the radar device 1 is disposed so as not to be parallel to the bumper B. For example, as shown in FIG. 2, if the portion of the bumper B facing the radar device 1 is formed along the vehicle up-down direction D2, which is the vertical direction, the radar device 1 is disposed so as to be inclined with respect to the vehicle up-down direction D2, which is the vertical direction. The reason why the radar device 1 is disposed so as not to be parallel to the bumper B in this way will be described later.

[0019] A specific configuration of the radar device 1 will be described below.

[0020] The radar device 1 can employ an FMCW method or an FCM method as a signal modulation method. The radar device 1 has a chirp center frequency in a frequency band corresponding to millimeter waves (for example, 76.5 GHz). The radar device 1 is configured to transmit a transmission wave, which is a millimeter-wave band radar wave, toward the space outside the vehicle, and to receive a reflected wave, which is a radio wave in a frequency band corresponding to the transmission wave. That is, the radar device 1 transmits a transmission wave falling within a predetermined frequency band toward the space outside, and receives a reflected wave falling within the frequency band from the space outside.

[0021] The operating frequency of the radio waves transmitted and received by the radar device 1 is not limited to a frequency corresponding to millimeter waves, and may be a frequency other than millimeter waves.

[0022] 2 and 3, the radar device 1 includes an antenna board 10, a control circuit 20, a signal generating unit 30, a transmitting unit 40, a receiving unit 50, a signal processing unit 60, a transmitting antenna array 70, and a receiving antenna array 80. The radar device 1 further includes an LO amplifier 90 and a mixer 95.

[0023] The antenna substrate 10 is a PCB (printed circuit board) on which various components constituting the radar device 1 are mounted, and has an antenna surface 11 on which these components are mounted. The control circuit 20, signal generation unit 30, transmitter unit 40, receiver unit 50, signal processing unit 60, transmitting antenna array 70, receiving antenna array 80, LO amplifier 90, and mixer 95 are arranged on the antenna surface 11. The antenna surface 11 is a surface facing the antenna-facing surface, which is the inner surface B1 of the bumper B. In the radar device 1, for example, the receiving antenna array 80 has multiple (e.g., four) receiving RX channels, and the radar device 1 is able to calculate the distance to the target, the presence angle, etc. by combining and processing the signals of each receiving RX channel.

[0024] The control circuit 20 is a control unit that executes predetermined control processing to perform various controls on the signal generating unit 30, the transmitting unit 40, and the receiving unit 50. The control circuit 20 may be realized as a microcomputer equipped with a CPU, nonvolatile memory (e.g., flash memory), volatile memory (e.g., RAM), etc. In this case, the CPU executes a program recorded in the nonvolatile memory, and the control circuit 20 uses the volatile memory as a working area during execution to perform various processes described below. Alternatively, the control circuit 20 may be a dedicated circuit configured to perform various processes described below.

[0025] The signal generating unit 30 includes, for example, a PLL and a multiplier (not shown), and generates a local signal to be output to the transmitting unit 40, as well as a local signal to be output to the receiving unit 50. The signal generating unit 30 outputs a TX signal to the transmitting unit 40. The signal generating unit 30 also outputs a local signal from the PLL to a receiving RX channel. The local signal output to the receiving RX by the PLL of the signal generating unit 30 is, for example, a 76.5 GHz signal.

[0026] The transmitter 40 includes a variable gain amplifier 41, a plurality of phase shifters 42, an amplifier 43, etc., and is connected to the transmitting antenna array 70. The variable gain amplifier 41 amplifies the TX signal received from the signal generator 30, and is configured to be able to adjust the amplification degree based on a control signal transmitted from the control circuit 20. The phase shifter 42 shifts the phase of the signal amplified by the variable gain amplifier 41 by a phase shift value φtx, and is configured to be able to change the magnitude of the phase shift value φtx based on a control signal transmitted from the control circuit 20. The amplifier 43 is a so-called power amplifier, and amplifies the output signal output by the phase shifter 42. The phase shifter 42 is electrically connected to the transmitting antenna array 70 via the amplifier 43.

[0027] The transmitting antenna array 70 is configured with a phased array antenna, and outputs a transmission wave toward a target via a bumper B. The wave transmitted from the transmitting antenna array 70 and reflected by the target is input to the receiving antenna array 80.

[0028] The receiving antenna array 80 is configured with a phased array antenna, and receives reflected waves that are reflected by a target and pass through the bumper B. The receiving antenna array 80 then outputs a signal corresponding to the received reflected waves to the receiving unit 50. The transmitting antenna array 70 and the receiving antenna array 80 will be described in detail later.

[0029] The receiving unit 50 is connected to the receiving antenna array 80. The receiving unit 50 has a plurality of receiving RX channels each having the same configuration. Each receiving unit 50 includes a variable gain amplifier 51, a plurality of phase shifters 52, an amplifier 53, etc. The phase shifter 52 is electrically connected to the receiving antenna array 80 via the variable gain amplifier 51.

[0030] The variable gain amplifier 51 amplifies the signal received from the receiving antenna array 80 when it receives the signal, and is configured to be able to adjust the amplification degree based on a control signal transmitted from the control circuit 20. The phase shifter 52 shifts the phase of the signal amplified by the variable gain amplifier 51 by a phase shift value φrx, and is configured to be able to change the magnitude of the phase shift value φrx based on a control signal transmitted from the control circuit 20. The amplifier 53 amplifies the phase-shifted signal of the phase shifter 52 and outputs it for each of the multiple receiving RX channels.

[0031] The LO amplifier 90 amplifies the local signal output by the PLL of the signal generating unit 30. When the signal generating unit 30 outputs a local signal to the receiving unit 50, the LO amplifier 90 amplifies the local signal and outputs it to the transmitting unit 40 and the mixer 95.

[0032] The mixer 95 mixes the signal amplified by the amplifier 53 with the signal amplified by the LO amplifier 90. The mixer 95 outputs an IF signal obtained by mixing the signal amplified by the amplifier 53 with the signal amplified by the LO amplifier 90 to the signal processing unit 60.

[0033] The signal processing unit 60 calculates the distance to the target, the existence angle, etc. Similar to the control circuit 20, the signal processing unit 60 is configured with a microcomputer equipped with a CPU, a non-volatile memory, a volatile memory, etc. The signal processing unit 60 includes an IF filter (not shown), and performs filtering on the IF signal output from the mixer 95 using the IF filter, followed by A / D conversion, and then performs signal processing such as digital beam forming using the FFT result to calculate the distance to the target, the existence angle, etc.

[0034] The control circuit 20 controls the beam scanning angle by controlling the phase shift value φtx of the phase shifter 42 and the phase shift value φrx of the phase shifter 52 of each receiving channel.

[0035] Next, the detailed structures of the transmitting antenna array 70 and the receiving antenna array 80, which are configured by phased array antennas used in such a radar device 1, will be described with reference to FIGS.

[0036] First, we will explain the arraying technology of the transmitting antenna array 70 and the receiving antenna array 80. Antenna arraying technology is a technology that combines antenna signals from multiple antennas arranged at half-wavelength (i.e., 0.5λ) intervals. Arraying technology can increase the number of antennas and achieve high gain. Furthermore, arraying technology can increase the array area, making it possible to narrow the beam, which is particularly advantageous for long-range radar applications where detection distance is required. In addition, the phase of multiple arranged antennas can be rotated by the phase shifter 42 to form an equal phase plane between the multiple antennas, making it possible to direct the beam at any angle.

[0037] As shown in Fig. 4, the transmitting antenna array 70 is used as a phased array antenna suitable for the present invention, and is configured by combining a plurality of transmitting-on elements 71a and 71c electrically connected to the transmitting unit 40 and a plurality of transmitting-off elements 71b that are not electrically connected to the transmitting unit 40. These transmitting-on elements 71a and 71c and the transmitting-off elements 71b are arranged on the antenna surface 11. In Fig. 4, the transmitting-on elements 71a are shown in black, the transmitting-on elements 71c are hatched with diagonal lines, and the transmitting-off elements 71b are shown in white. Hereinafter, the transmitting-on elements 71a, 71c, and the transmitting-off elements 71b may be collectively referred to as transmitting elements 71.

[0038] 4, each transmitting element 71 has a rectangular metal surface. The outer frame of the transmitting antenna array 70 is configured as a square, and the rectangular transmitting elements 71 are arranged in the areas of the vertices of a grid pattern within the outer frame of the transmitting antenna array 70.

[0039] In this embodiment, the transmitting antenna array 70 has transmitting elements 71 arranged in a two-dimensional predetermined area partitioned into 16 rows and 12 columns. In this embodiment, as shown in Fig. 4, 12 transmitting elements 71 are arranged side by side in the X direction and 16 transmitting elements 71 are arranged side by side in the Y direction. When the radar device 1 is installed on a vehicle C, the radar device 1 is arranged so that 12 transmitting elements 71 are arranged side by side in the left-right direction D3 of the vehicle and 16 transmitting elements 71 are arranged side by side in the up-down direction D2 of the vehicle.

[0040] However, the configuration of the transmission-on elements 71a, 71c and the transmission-off elements 71b in the transmission antenna array 70 is not limited to this, and may be arranged in 12 rows and 8 columns, for example.

[0041] The plurality of transmission-on elements 71a and the plurality of transmission-on elements 71c of the transmission antenna array 70 are connected to the transmitter 40 by transmission lines provided on the surface of the antenna substrate 10. By combining and radiating beam energy from the plurality of transmission-on elements 71a and the plurality of transmission-on elements 71c, a transmission beam having directionality toward the antenna surface 11 can be formed.

[0042] The beam angle, which is the transmission direction of the transmission waves transmitted by the transmitting antenna array 70, is electronically changed by the phase shifter 42 controlling the phase shift value φtx of each of the signals transmitted to the multiple transmission-on elements 71a and multiple transmission-on elements 71c of the transmitting antenna array 70 via the amplifier 43. The phase shift values ​​φtx of each of the signals transmitted to the transmission-on elements 71a and 71c, which are controlled by the phase shifter 42, are set based on control signals transmitted from the control circuit 20. Therefore, the control circuit 20 of this embodiment functions as a control unit that controls the phase and amplitude of each of the transmission-on elements 71a and 71c to change the beam angle of the transmission waves transmitted by the transmitting antenna array 70.

[0043] The control circuit 20 controls the beam angles of the transmission waves in the vehicle up-down direction D2 and the vehicle left-right direction D3 with respect to the direction perpendicular to the metallic rectangular surfaces of the transmission-on element 71a and the transmission-on element 71c. In other words, the control circuit 20 adjusts the transmission angles of the transmission waves in the vehicle up-down direction D2 and the vehicle left-right direction D3 with respect to the direction perpendicular to the antenna surface 11 by controlling the phase shifter 42.

[0044] Hereinafter, as shown in FIG. 2 and the like, a direction perpendicular to the antenna surface 11 is defined as an antenna perpendicular direction D4, and a transmission angle in the vehicle vertical direction D2 relative to the antenna perpendicular direction D4 is defined as a scan angle θ S Also called the scan angle θ S is the angle formed by the direction perpendicular to the antenna plane 11 and the direction along the beam angle.

[0045] A receiving antenna array 80 is provided for each of the multiple receiving channels. Each receiving antenna array 80 for each receiving channel is used as a phased array antenna suitable for the present invention. The receiving antenna array 80 has the same configuration as the transmitting antenna array 70, and as shown in FIG. 5, is configured by combining multiple receiving-on elements 81a, 81c electrically connected to the receiving unit 50 and multiple receiving-off elements 81b not electrically connected to the receiving unit 50. These multiple receiving-on elements 81a, 81c and multiple receiving-off elements 81b are arranged on the antenna plane 11. Hereinafter, the receiving-on elements 81a, 81c and receiving-off elements 81b may be collectively referred to as receiving elements 81.

[0046] 5, each receiving element 81 has a rectangular metal surface. The outer frame of the receiving antenna array 80 is configured in a square shape, and the rectangular receiving elements 81 are arranged in the areas of the vertices of a grid pattern within the outer frame of the receiving antenna array 80.

[0047] In this embodiment, the receiving antenna array 80 has an outer frame with the same shape as that of the transmitting antenna array 70. Specifically, the receiving antenna array 80 has receiving elements 81 arranged in a two-dimensional predetermined area partitioned into 16 rows and 12 columns.

[0048] 5, in this embodiment, 16 receiving elements 81 are arranged side by side in the X direction and 12 receiving elements 81 are arranged side by side in the Y direction. When the radar device 1 is installed on a vehicle C, the radar device 1 is arranged so that 12 receiving elements 81 are arranged side by side in the left-right direction D3 of the vehicle and 16 receiving elements 81 are arranged side by side in the up-down direction D2 of the vehicle.

[0049] The plurality of reception-on elements 81a and the plurality of reception-on elements 81c of the reception antenna array 80 are connected to the receiving unit 50 by transmission lines provided on the surface of the antenna substrate 10. By receiving signals from the plurality of reception-on elements 81a and the plurality of reception-on elements 81c, it is possible to impart directionality to the received reception beam.

[0050] 2, four receiving antenna arrays 80 are arranged side by side in the vehicle left-right direction D3 on the antenna surface 11. The receiving antenna array 80 is also arranged side by side with the transmitting antenna array 70 on the antenna surface 11. The receiving antenna array 80 and the transmitting antenna array 70 are arranged side by side in a direction different from the vehicle up-down direction D2. In this embodiment, the receiving antenna array 80 and the transmitting antenna array 70 are arranged side by side in the vehicle left-right direction D3.

[0051] The transmitting antenna array 70 and the receiving antenna array 80 are two-dimensional arrays with grating lobe cancellers. The transmitting antenna array 70 and the receiving antenna array 80 of this embodiment are array arrangements characterized by being able to simultaneously reduce the number of phase shifters 42 and 52 and suppress grating lobes, and are suitable for use in the present invention because they can achieve narrow beamwidths with half-widths of less than 10°. Note that the specific configurations of the transmitting elements 71 of the transmitting antenna array 70 and the receiving elements 81 of the receiving antenna array 80 were already publicly known or well-known at the time of filing this application (see, for example, JP 2022-191769 A and JP 2023-177013 A).

[0052] When the radar device 1 is disposed behind the bumper B as in this embodiment, a portion of the transmission wave transmitted from the radar device 1 may be reflected by the inner surface B1 of the bumper B without passing through the bumper B. In this case, the radar device 1 receives a reflected wave in which the reflected wave reflected by the target and the reflected wave reflected by the inner surface B1 of the bumper B overlap. Receiving such a reflected wave in which the reflected wave reflected by the target and the reflected wave reflected by the inner surface B1 of the bumper B overlap can cause errors in the distance to the target, the position of the target, the shape of the target, and the like detected by the radar device 1. Note that reflections from the bumper B are more likely to occur when the bumper B is made of a reflective material, such as a shiny material. Furthermore, if a component such as an emblem attached to the bumper B is made of a shiny material and the component made of the shiny material is in the path of the transmission wave, reflections from the bumper B are more likely to occur.

[0053] Furthermore, when the radar device 1 and the bumper B are nearly parallel, the reflected waves from the bumper B interfere with the transmitted waves from the radar device 1 or the reflected waves from the target. This disrupts the directivity patterns of the transmitting antenna array 70 and the receiving antenna array 80 of the radar device 1, causing amplitude ripples in the signals obtained by the radar device 1 performing signal processing. This leads to degradation of radar quality, such as a decrease in the maximum detection distance and angle measurement errors due to insufficient gain. Furthermore, when the reflected waves from the bumper B are reflected again by the radar device 1, multiple reflections occur, whereby reflections are repeated between the bumper B and the radar device 1. When multiple reflections occur strongly, amplitude ripples and angle measurement errors occur not only in the transmitted and received wave signals from the front of the radar device 1 but also in the transmitted and received wave signals from various angles close to the transmission width and reception width of the transmitted and received waves.

[0054] Therefore, the radar device 1 of this embodiment is arranged so as not to be parallel to the bumper B, and employs a phased array antenna, thereby making it possible to solve these problems. The reasons why the radar device 1 of this embodiment is arranged so as not to be parallel to the bumper B and why a phased array antenna is employed will be explained below with reference to Figures 6 to 8. Note that in Figures 6 to 8, among the curves showing radio waves, solid lines indicate transmitted waves, and dashed lines indicate reflected waves.

[0055] 6 shows a comparative radar device 100 for comparison, which, unlike the radar device 1 of this embodiment that employs a phased array antenna, has a transmitter / receiver unit that transmits and receives radio waves and is configured with a single transmitter antenna 110 and a single receiver antenna 120. When the comparative radar device 100 is configured with a single transmitter antenna 110 and a single receiver antenna 120, the beam half-width is generally about 40° to 60°, and is characterized by a relatively wide beam width BW. Furthermore, when the comparative radar device 100 is configured with a single transmitter antenna 110 and a single receiver antenna 120, the transmission and reception performance of the comparative radar device 100 has a relatively low gain.

[0056] 6, when the comparative radar device 100 is disposed behind the bumper B so as to face the bumper B, the comparative radar device 100 and the bumper B are disposed so as to be parallel to each other. In this case, when the transmitting antenna 110 of the comparative radar device 100 transmits a transmission wave toward the vehicle front D1a, the transmission wave propagates toward the vehicle front D1a while spreading in the vehicle up-down direction D2 and the vehicle left-right direction D3.

[0057] A part of the transmitted wave transmitted toward the bumper B passes through the bumper B, and the remaining part is reflected by the inner surface B1 of the bumper B. The reflected wave reflected by the inner surface B1 of the bumper B propagates toward the rear D1b of the vehicle while spreading in the vehicle vertical direction D2 and the vehicle lateral direction D3. Then, multiple reflections occur between the bumper B and the radar device 1.

[0058] As a result, the receiving antenna 120 of the comparison radar device 100 receives a reflected wave that is a combination of a reflected wave from the target and a reflected wave that has been reflected once or multiple times from the inner surface B1 of the bumper B. In this case, when the comparison radar device 100 acquires information about the target, it is affected by the reflected wave from the bumper B. For this reason, the information acquired by the comparison radar device 100 may contain errors.

[0059] Furthermore, when the reflected wave reflected from the target and the reflected wave reflected from the inner surface B1 of the bumper B overlap, if the phases of these two reflected waves are in phase, the amplitudes of the overlapping reflected waves reinforce each other. On the other hand, if the phases of the reflected wave reflected from the target and the reflected wave reflected from the inner surface B1 of the bumper B are opposite to each other, the reflected waves cancel each other out.

[0060] Therefore, when two reflected waves having the same phase are received, the influence on the comparison radar device 100 is large, and when two reflected waves having opposite phases are received, the influence on the comparison radar device 100 is small.

[0061] When the comparison radar device 100 is disposed parallel to the bumper B, the receiving antenna 120 receives reflected waves of the same phase over a wide range. Therefore, when the comparison radar device 100 receives two reflected waves that are in phase with each other, the comparison radar device 100 is likely to be significantly affected.

[0062] In contrast, as described above, the radar device 1 of this embodiment employs a transmitting antenna array 70 and a receiving antenna array 80 configured with phased array antennas as transmitting and receiving units for transmitting and receiving radio waves. When the radar device 1 employs a phased array antenna, the beam half-width is generally less than 10°, and the beam width BW is relatively narrow. Furthermore, when the radar device 1 employs a phased array, the transmission and reception performance of the radar device 1 has a relatively high gain. Furthermore, when the radar device 1 employs a phased array, unlike the comparative radar device 100, it has beam scanning capability, and generally has beam scanning capability in the range of approximately -60° to +60° in the horizontal direction and -20° to +20° in the vertical direction.

[0063] 7, it is assumed that the radar device 1 of this embodiment is disposed parallel to the bumper B. In this case, when each of the multiple transmitting elements 71 of the transmitting antenna array 70 of the radar device 1 transmits a transmission wave toward the vehicle front D1a, the transmission wave propagates toward the vehicle front D1a while spreading in the vehicle up-down direction D2 and the vehicle left-right direction D3. However, the transmission wave transmitted by the transmitting antenna array 70 is less likely to spread than the transmission wave transmitted by the transmitting antenna 110 of the comparative radar device 100.

[0064] Of the transmitted waves toward the bumper B, the reflected waves reflected by the inner surface B1 of the bumper B propagate toward the rear D1b of the vehicle while spreading in the vehicle vertical direction D2 and the vehicle horizontal direction D3. Then, multiple reflections occur between the inner surface B1 of the bumper B and the radar device 1.

[0065] As a result, the receiving antenna array 80 of the radar device 1 receives a reflected wave that is a combination of a reflected wave from the target and a reflected wave that has been reflected once or multiple times from the inner surface B1 of the bumper B. In this case, like the comparative radar device 100, the radar device 1 is affected by the reflected wave from the bumper B when acquiring information about the target. Therefore, the information acquired by the radar device 1 may contain errors.

[0066] Furthermore, when the radar device 1 is disposed parallel to the bumper B, each of the multiple receiving elements 81 receives the reflected wave reflected by the inner surface B1 of the bumper B at approximately the same timing. Therefore, the phases of the two overlapping reflected waves received by each of the multiple receiving elements 81 are in phase. Therefore, when each of the multiple receiving elements 81 of the radar device 1 receives two reflected waves that are in phase with each other, the radar device 1 is likely to be significantly affected.

[0067] In contrast to this, when the radar device 1 is disposed behind the bumper B so as to face the bumper B, it is assumed that the radar device 1 and the bumper B are not disposed parallel to each other, as shown in Fig. 8. Specifically, it is assumed that the bumper B is formed along the vehicle vertical direction D2, and the radar device 1 is disposed at an angle with respect to the vehicle vertical direction D2 so that a portion of the radar device 1 on the vehicle upper D2a side approaches the bumper B and a portion of the radar device 1 on the vehicle lower D2b side moves away from the bumper B.

[0068] In this case, when the reflected wave reflected by the inner surface B1 of the bumper B is reflected by the radar device 1, the reflected wave is reflected at a position shifted in the vehicle up-down direction D2 from the vehicle front D1a. Specifically, the reflected wave reflected by the radar device 1 is reflected at a position shifted in the horizontal direction to the vehicle downward D2b.

[0069] Therefore, even if a part of the reflected wave reflected by the radar device 1 is reflected again by the inner surface B1 of the bumper B, this reflected wave will travel toward the vehicle rear D1b and downward D2b in the vehicle up-down direction D2. If the reflected wave reflected again by the inner surface B1 of the bumper B misses the receiving antenna array 80 of the radar device 1, the radar device 1 will not receive this reflected wave. In other words, if the radar device 1 and the bumper B are arranged so as not to be parallel, multiple reflections will be less likely to occur between the bumper B and the radar device 1.

[0070] In this way, by arranging the radar device 1 and the bumper B so that they are not parallel to each other, the reflected waves reflected by the inner surface B1 of the bumper B are physically dispersed outside the receiving range of the radar device 1, thereby suppressing the influence of the reflected waves reflected by the bumper B.

[0071] 8, when the radar device 1 and the bumper B are arranged so as not to be parallel, the multiple receiving elements 81 receive the reflected waves reflected by the inner surface B1 of the bumper B at different times. That is, there is a difference in the reception timing of the reflected waves reflected by the bumper B received by each of the multiple receiving elements 81. As a result, the phases of the reflected waves reflected by the inner surface B1 of the bumper B received by each of the multiple receiving elements 81 are shifted from each other. In other words, the reflected waves reflected by the inner surface B1 of the bumper B received by each of the multiple receiving elements 81 do not have the same amplitude.

[0072] Therefore, even if each of the multiple receiving elements 81 receives a reflected wave that is an overlap of a reflected wave reflected by a target and a reflected wave reflected by the inner surface B1 of the bumper B, the receiving elements 81 are less likely to be affected by the overlapping reflected waves.

[0073] For the above reasons, the radar device 1 of this embodiment is disposed so as not to be parallel to the bumper B, and employs a phased array antenna. However, if the radar device 1 is configured to transmit transmission waves along the antenna orthogonal direction D4, the radar device 1 cannot transmit transmission waves along the vehicle front D1a. In this case, it becomes difficult to obtain information about targets present in the vehicle front D1a of the host vehicle.

[0074] For this reason, the radar device 1 of this embodiment employs a phased array for the transmitting antenna array 70, thereby adjusting the scan angle θ according to the installation angle of the radar device 1. S This allows the transmission wave to be transmitted along the front D1a of the vehicle while suppressing the effects of multiple reflections.

[0075] Furthermore, the radar device 1 of this embodiment employs a phased array for the transmitting antenna array 70, which makes it difficult for energy to spread in the vehicle's vertical direction D2 and horizontal direction D3 when the transmitted wave travels toward the vehicle's front D1a due to the narrow beam width BW. As a result, the radar device 1 is less susceptible to reflections at angles larger than the beam width BW. In contrast, the comparative radar device 100, which has a single transmitting antenna 110 without a phased array, has a wider beam width BW than the radar device 1 of this embodiment, e.g., a half-width of approximately 40° to 60°, and has a uniform gain over such a wide angular range. As a result, the comparative radar device 100 is more susceptible to reflections over a wide angular range.

[0076] Specifically, the phases of the transmission-on elements 71a, 71c and the transmission-off elements 71b of the transmission antenna array 70 are controlled by the phase shifters 42, 52 so that the scan angle adjustment range as a countermeasure against reflection of the transmission wave in the vehicle up-down direction D2 is within a range of 3° or more and less than 10°. Therefore, when the radar device 1 transmits a transmission wave toward the front D1a of the vehicle, it is possible to transmit the transmission wave to a target that is located further away and obtain information about the target that is located further away.

[0077] Furthermore, the radar device 1 of this embodiment employs a phased array for the receiving antenna array 80, which makes it easier to limit the reception range in the vehicle up-down direction D2 and the vehicle left-right direction D3 when the receiving antenna array 80 receives reflected waves. Therefore, when the radar device 1 receives reflected waves from the front D1a of the vehicle, it is possible to limit the reception direction of the reflected waves.

[0078] Next, a description will be given of specific installation angles of the bumper B and the radar device 1. In describing specific installation angles of the radar device 1, the installation angles of the bumper B and the radar device 1 will be defined as shown in FIG.

[0079] As shown in Fig. 9, the angle of the bumper B when the portion of the bumper B on the upper D2a side of the vehicle is inclined toward the front D1a of the vehicle and the portion of the bumper B on the lower D2b side of the vehicle is inclined toward the rear D1b of the vehicle is indicated by a positive numerical value. On the other hand, the angle of the bumper B when the portion of the bumper B on the upper D2a side of the vehicle is inclined toward the rear D1b of the vehicle and the portion of the bumper B on the lower D2b side of the vehicle is inclined toward the front D1a of the vehicle is indicated by a negative numerical value. Hereinafter, as shown in Fig. 9 etc., the angle of the bumper B with respect to the vehicle up-down direction D2 is referred to as the bumper angle θ B Also called.

[0080] As shown in FIGS. 9 and 10, when the thickness of the bumper B in the vehicle longitudinal direction D1 at the portion facing the radar device 1 is constant, the bumper angle θ B is the angle of the inner surface B1 of the bumper B, which faces the radar device 1, with respect to the vehicle vertical direction D2. That is, the bumper angle θ B is the angle of the surface of the bumper B that reflects a part of the transmission wave transmitted from the radar device 1 with respect to the vehicle vertical direction D2. In other words, the bumper angle θ B is the angle formed by the inner surface B1 of the bumper B and the vertical direction. As shown in FIG. 10, when the bumper B is disposed so that the extension direction of the inner surface B1 of the bumper B is along the vertical direction, the bumper angle θ B is 0°.

[0081] Furthermore, the angle of the radar device 1 when the portion of the antenna board 10 of the radar device 1 on the vehicle upper D2a side is inclined toward the vehicle front D1a and the portion of the antenna board 10 on the vehicle lower D2b side is inclined toward the vehicle rear D1b is indicated by a positive numerical value. In other words, when the portion of the antenna board 10 on the vehicle upper D2a side is inclined toward the bumper B and the portion of the antenna board 10 on the vehicle lower D2b side is inclined away from the bumper B, the angle of the radar device 1 is a positive numerical value.

[0082] In contrast, the angle of the radar device 1 when the portion of the antenna board 10 of the radar device 1 on the vehicle upper D2a side is tilted toward the vehicle rear D1b and the portion of the antenna board 10 on the vehicle lower D2b side is tilted toward the vehicle front D1a is shown as a negative value. That is, when the portion of the antenna board 10 on the vehicle upper D2a side is tilted away from the bumper B and the portion of the antenna board 10 on the vehicle lower D2b side is tilted toward the bumper B, the angle of the radar device 1 becomes a negative value. Hereinafter, as shown in Figs. 2 and 9, the angle of the antenna board 10 with respect to the vehicle up-down direction D2 is referred to as the radar angle θ R Also called.

[0083] Radar angle θ R is the angle formed by the direction in which the antenna surface 11 on which the transmitting antenna array 70 and the receiving antenna array 80 of the antenna substrate 10 are mounted extends and the vertical direction, and is the tilt angle of the radar device 1. R is an angle approximately equal to the angle of the rectangular metal surfaces of the transmitting-on elements 71a and 71c of the transmitting antenna array 70 with respect to the vehicle vertical direction D2. R is an angle approximately equal to the angle of the rectangular metal surfaces of the reception-on elements 81a and 81c of the reception antenna array 80 relative to the vehicle vertical direction D2.

[0084] The bumper angle θ Band radar angle θ R is set so as to satisfy both the following formula 1 and formula 2.

[0085] [Number 1] θ R ≠0

[0086] [Number 2] |θ B -θ R |=5° As shown in Equation 1, the radar device 1 of this embodiment calculates the radar angle θ R The antenna substrate 10 is disposed so as to be inclined either to the positive side or the negative side with respect to the vertical direction so that the angle D4 is different from 0°. In other words, the radar device 1 is disposed so that the antenna surface 11 is inclined either to the vehicle front D1a side or the vehicle rear D1b side with respect to the vertical direction so that the antenna orthogonal direction D4 is not aligned with the vehicle front-rear direction D1.

[0087] Furthermore, as shown in Equation 2, the radar device 1 of this embodiment calculates the bumper angle θ B and radar angle θ R In other words, the radar device 1 is positioned so that the absolute value of the difference between the bumper angle θ B and radar angle θ R The angle is set so that the difference between the two is either +5° or -5°.

[0088] Here, in the radar device 1 of this embodiment, as shown in FIG. 10, the thickness of the portion of the bumper B facing the radar device 1 is constant, and the bumper angle θ B In this case, the radar device 1 of this embodiment is applied to a vehicle C having a bumper B with a radar angle θ R is positioned on the vehicle so that the angle is +5°.

[0089] Next, the bumper angle θ is set so as to satisfy both the above formula 1 and formula 2. B and radar angle θ R When the scan angle θ is set S The scan angle θS In explaining the above, the scanning angle θ of the transmission wave changed by the control circuit 20 is S is defined as follows: As shown in FIG. 9, the scan angle θ when the control circuit 20 changes the beam angle of the transmission wave to the vehicle upper D2a side with respect to the antenna orthogonal direction D4. S is expressed as a positive numerical value, and the scan angle θ when the control circuit 20 changes the beam angle of the transmission wave to the vehicle downward D2b side based on the antenna orthogonal direction D4 is expressed as a positive numerical value. S is indicated by a negative number.

[0090] In this embodiment, the control circuit 20 adjusts the beam angle of the transmission wave by adjusting the scan angle θ S is the radar angle θ R Specifically, the control circuit 20 of this embodiment adjusts the beam angle of the transmission wave so that the beam angle approaches the scan angle θ S The beam angle is adjusted so that the following formula 3 is satisfied.

[0091] [Number 3] θ S =θ R As shown in Equation 3, the scan angle θ is set so that the beam angle in the vehicle vertical direction D2 is emitted parallel to the ground (i.e., horizontally). S is the radar angle θ R That is, the control circuit 20 sets the scan angle θ S is the radar angle θ R The beam angle of the transmitted wave is adjusted to +5°, which is the angle equal to the scan angle θ S is the radar angle θ R When the control circuit 20 adjusts the beam angle of the transmission wave so that the angle is equal to the angle of the beam, a slight error may be included, and the angle does not have to be equal in the strict sense.

[0092] The control circuit 20 of this embodiment controls the scan angle θ SSpecifically, the control circuit 20 controls the phase shifter 42 so that the difference between the phase shift values ​​φtx of adjacent transmitting elements 71 for the 16 transmitting elements 71 arranged in the vehicle up-down direction D2 is equal to or smaller than the target scan angle θ S , which is approximately three times larger than the phase shift value φtx of the transmitting element 71. For example, when the phase shift value φtx of the transmitting element 71 positioned furthest above the vehicle D2a is set to 0°, the control circuit 20 sets the phase shift value φtx of the second transmitting element 71 from the vehicle above D2a side to 15.7°. Then, the control circuit 20 sets the phase shift value φtx of each transmitting element 71 so that the phase shift value φtx of each transmitting element 71 increases by 15.7° from the vehicle above D2a side to the vehicle below D2b side.

[0093] As a result, the beam angle of the transmission wave transmitted by the radar device 1 is parallel to the horizontal direction and along the direction D1a ahead of the vehicle.

[0094] Next, the results of a test conducted to confirm the effects of the radar device 1 of this embodiment will be described with reference to Figs. 11 to 15. In the test to obtain the results shown in Fig. 11, a target was placed in front of the radar device 1, and an experiment was conducted to compare the signal strength when a reflected wave from the target was received. In this experiment, the bumper angle θ B , radar angle θ R and scan angle θ S When each is set to 0°, and when the bumper angle θ B is set to 0°, and the radar angle θ R and scan angle θ S The signal strength was compared when the angle was set to +5° for each case. That is, the signal strength was compared when the radar device 1 was placed so that it was parallel to the bumper B, and when the radar device 1 was placed at an angle of +5° with respect to the installation angle of the bumper B and the beam angle of the transmission wave was adjusted according to the installation angle of the bumper B. Furthermore, in this experiment, the signal strength was compared when the distance between the bumper B and the radar device 1 was changed in various ways.

[0095] The dashed line in FIG. 11 indicates the bumper angle θ B , radar angle θ R and scan angle θ S The solid line in Fig. 11 shows the signal strength when the bumper angle θ B is set to 0°, and the radar angle θ R and scan angle θ S The bar graph in Fig. 11 shows the signal strength when the bumper angle θ is set to +5°. B , radar angle θ R and scan angle θ S Signal strength and bumper angle θ when each is set to 0° B is set to 0°, and the radar angle θ R and scan angle θ S The difference in signal strength when each is set to +5° is shown.

[0096] Below, bumper angle θ B is set to 0°, and the radar angle θ R and scan angle θ S The arrangement when each of the bumper angles is set to +5° is referred to as the arrangement of this embodiment. B , radar angle θ R and scan angle θ S The arrangement when each is set to 0° is referred to as the comparative arrangement.

[0097] In the comparative arrangement, when a transmission wave is transmitted from the radar device 1 toward a target, the reflected wave reflected by the bumper B interferes with the directivity pattern of the transmitting antenna array 70, affecting the signal strength detected by the radar device 1. As the distance between the bumper B and the radar device 1 gradually increases, the phase of the reflected wave reflected by the bumper B interferes with the directivity pattern of the transmitting antenna array 70, causing the amplitude of the signal strength to periodically increase and decrease depending on the distance between the radar device 1 and the bumper B, resulting in ripples. In the comparative arrangement, as shown by the dashed line in FIG. 11 , the amplitude of the signal strength alternates between high and low at intervals of 1 mm, which is approximately ¼ of the wavelength of the 76.5 GHz transmission wave transmitted by the radar device 1. The reason for this periodic increase and decrease in the amplitude of the signal strength will now be described.

[0098] When the distance between the bumper B and the radar device 1 is gradually increased, the round-trip distance of the radio waves between the radar device 1 and the bumper B gradually changes by twice the distance between the bumper B and the radar device 1. Therefore, when the distance between the bumper B and the radar device 1 is shifted by 1 / 4 of the wavelength, the reflected wave received by the radar device 1 is shifted by 1 / 2 wavelength. In other words, the phase of the reflected wave received by the radar device 1 is shifted by 180°. Therefore, when the radar device 1 is strongly affected by the reflected wave, a periodic change in amplitude can be confirmed with respect to the distance between the bumper B and the radar device 1, as shown by the dashed line in FIG. 11.

[0099] In contrast, in the arrangement of this embodiment, as described above, the influence of reflection can be reduced by arraying the transmitting antenna array 70 and the receiving antenna array 80, by arranging the radar device 1 at an angle relative to the installation angle of the bumper B, and by electronically controlling the beam angle by the control circuit 20 to shift the phase of each of the multiple transmitting elements 71 before emitting radio waves. The results are shown by the solid line in Figure 11. The right axis of Figure 11 also shows the difference in amplitude ripple between the comparative arrangement and the arrangement of this embodiment.

[0100] As shown in Figure 8, when a transmission wave is transmitted from the radar device 1 toward a target, the reflected wave reflected by the inner surface B1 of the bumper B does not directly reach the entire antenna surface 11 of the antenna substrate 10 at the same time, which reduces interference between the transmitted wave and the reflected wave. R and scan angle θ S By setting each to +5°, the beam angle is adjusted to the tilt angle of the radar device 1, and the phases of the multiple transmitting elements 71 and the multiple receiving elements 81 are set to be out of phase, thereby avoiding interference with reflected waves uniformly and simultaneously across the entire transmitting antenna array 70 and receiving antenna array 80.

[0101] Furthermore, the secondary reflection component that is re-reflected by the antenna surface 11 of the antenna substrate 10 travels toward the vehicle downward direction D2b. Therefore, multiple reflections are less likely to occur between the bumper B and the radar device 1. Therefore, the radar device 1 is less susceptible to the influence of the signal strength caused by the occurrence of multiple reflections. As a result, in the arrangement of this embodiment, as shown by the solid line in FIG. 11, even if the distance between the bumper B and the radar device 1 is gradually increased, the change in signal strength is small. In other words, in the arrangement of this embodiment, the influence of multiple reflections can be suppressed compared to the comparative arrangement, and therefore the ripple in the signal strength is smaller.

[0102] 12 shows a comparison of horizontal beam scanning, comparing the signal strengths when the target is positioned directly in front of the radar device 1, 30° to one side in the vehicle left-right direction D3, and 30° to the other side in the vehicle left-right direction D3, in the comparative arrangement and the arrangement of this embodiment. The dashed lines in FIG. 12 indicate the signal strengths when the radar device 1 is positioned in the comparative arrangement and the target is positioned directly in front of the radar device 1, 30° to one side in the vehicle left-right direction D3, and 30° to the other side in the vehicle left-right direction D3. The solid lines indicate the signal strengths when the radar device 1 is positioned in the arrangement of this embodiment and the target is positioned directly in front of the radar device 1, 30° to one side in the vehicle left-right direction D3, and 30° to the other side in the vehicle left-right direction D3.

[0103] 12, when the radar device 1 was placed in the comparative arrangement, the beam waveform was disturbed by the influence of reflections, and a notch was included in the beam pattern at ±30° in the left-right direction D3 of the vehicle. In contrast, when the radar device 1 was placed in the arrangement of this embodiment, fluctuations in signal strength due to interference from reflections were suppressed compared to the comparative arrangement, and almost no notch was included in the signal strength in the left-right direction D3 of the vehicle.

[0104] In this way, the arrangement of this embodiment was able to stabilize the signal strength compared to the comparative arrangement.

[0105] As described above, the radar device 1 of this embodiment employs a phased array for the transmitting antenna array 70, which makes it difficult for the transmitted waves to spread in the vehicle vertical direction D2 and the vehicle horizontal direction D3. Furthermore, the radar device 1 of this embodiment employs a phased array for the receiving antenna array 80, which narrows the beam width BW, thereby attenuating the signals of reflected waves from angles other than those with the beam width BW, filtering out the reflections, and reducing the influence of the reflections.

[0106] Next, the verification results shown in Fig. 13 and Fig. 14 will be explained. In the verification to obtain the verification results shown in Fig. 13 and Fig. 14, an experiment was conducted in which a target was placed and the signal strength when a reflected wave from the target was received was compared. In this experiment, the bumper angle θ B is set to 0°, and the radar angle θ R The angle was changed in 1° increments within a range of 0° to 14° to change the distance between the bumper B and the radar device 1 in various ways, and the signal strengths were compared.

[0107] In addition, in Fig. 13, the radar angle θ is set in the range of 0° to 14°. R Specifically, the lines with triangles on them represent the radar angle θ R The line with a square on it indicates the signal strength when the radar angle θ is set to 0°. R The signal strength is shown when the radar angle θ is set to +2°.R The line with a diamond on it indicates the signal strength when the radar angle θ is set to +5°. R The signal strength is shown when the radar angle θ is set to +8°. The star-shaped line on the line indicates the radar angle θ R The line with a cross on it indicates the signal strength when the radar angle θ is set to +11°. R The signal strength is shown when the angle is set to +14°.

[0108] Radar angle θ indicated by a line with a triangle on it R The layout in which the radar angle θ is set to 0° is the same as the comparative layout in which the experiment was conducted to obtain the verification results shown in Figs. 11 and 12. In addition, the radar angle θ R The arrangement in which the angle is set to +5° is the same as the arrangement in this embodiment in which the experiment was conducted to obtain the verification results shown in FIGS.

[0109] As shown in Figure 13, the radar angle θ R In the configuration where the angle was set to 0°, as the distance between the bumper B and the radar device 1 increased, a distance-dependent increase or decrease in the signal, which indicates the degree of influence of residual reflection, of approximately 5 dB peak to peak was confirmed.

[0110] In contrast, the radar angle θ R In the arrangement where the radar angle θ was set to an angle different from 0°, the change in signal strength was small even when the distance between the bumper B and the radar device 1 was gradually increased. In other words, in the arrangement where the antenna surface 11 was inclined with respect to the vehicle vertical direction D2, the ripple in signal strength was smaller than in the comparative arrangement. In other words, R By arranging the antenna at an angle different from 0° so that the antenna surface 11 is not parallel to the inner surface B1 of the bumper B, the ripple was reduced compared to the comparative arrangement. In particular, with the arrangement of this embodiment, the difference between the maximum and minimum values ​​of the signal improved by about 3.7d compared to the difference between the maximum and minimum values ​​of the signal in the comparative arrangement, to about 1.3dB peak to peak.

[0111] 14 shows the relationship between the distance between the bumper B and the radar device 1 and the bumper angle θ B is set to 0°, and the radar angle θ R The ripple and signal strength were compared when the angle was changed in 1° increments in the range of 0° to 12°. Note that the dashed line in Fig. 14 indicates the ripple, and the solid line indicates the average value of the signal strength.

[0112] As shown in Figure 14, the radar angle θ R In the case of an arrangement where the radar angle θ is set to an angle other than 0°, R The ripple was significantly reduced compared to the arrangement where the radar angle θ was set to 0°. R In the case of an arrangement where the radar angle θ is set to an angle other than 0°, R Compared to the arrangement where the angle was set to 0°, the influence of reflection was reduced and the transmitted component of bumper B increased, so the average signal strength was able to be kept at the same level or higher.

[0113] Also, the radar angle θ R When the radar angle θ is set in the range of 0° to 6°, R As the angle increases from 0°, the signal strength increases. This is because the signal is less susceptible to multiple reflections.

[0114] Also, the radar angle θ R When the range is set to be greater than 7°, the radar angle θ R As the radar angle θ increases, the signal strength decreases. R If the angle is larger than a predetermined angle, it becomes difficult for the radar device 1 to transmit the transmission wave to the front D1a of the vehicle and also becomes difficult to receive the reflected wave from the front D1a of the vehicle, which reduces the performance of the radar device 1.

[0115] 15, in beam scanning of a typical phased array, the gain is highest in front of the radar device 1, and the gain tends to decrease as the tilt angle of the radar device 1 increases. Therefore, as a countermeasure against reflection from bumper B, it is desirable to tilt the radar device 1 with respect to the vertical direction, and when matching the beam angle to the tilt angle of the radar device 1, it is desirable to prevent the tilt angle and beam angle from becoming excessively large.

[0116] From the verification results described above, it is possible to obtain a relatively large received signal while reducing the ripple by adjusting the radar angle θ R and scan angle θ S It is desirable to set the radar angle θ to an angle in the range of 3° or more and less than 10°. R and scan angle θ S The angle was set to 5°, which was the angle at which the second strongest received signal could be obtained within the range of 3° or more and less than 10° and at which ripples could be sufficiently suppressed.

[0117] In this embodiment, the radar device 1 is mounted on a vehicle C, and the antenna surface 11 is disposed so as to be inclined with respect to the vehicle vertical direction D2. Then, the scan angle θ is set so as to satisfy the above-mentioned formula 3. S By setting the above, the radar device 1 is configured to be able to transmit a transmission wave toward the front D1a of the vehicle C when the body of the vehicle C is not tilted with respect to the horizontal direction, as shown in FIG.

[0118] However, depending on factors such as the number of occupants in the vehicle C and the tire air pressure, the vehicle C may tilt relative to the horizontal direction as shown in Fig. 17. For example, if the tire air pressure of the rear wheels is lower than that of the front wheels, the vehicle C may tilt so that the front D1a side of the vehicle C is directed upward D2a relative to the rear D1b side of the vehicle, as shown in Fig. 17. In this case, the scan angle θ is the same as when the body of the vehicle C is not tilted relative to the horizontal direction. SIn other words, if the scan angle θ is set so that the transmission wave travels horizontally toward the vehicle upper side D2a, the radar device 1 will not be able to transmit the transmission wave in the designed direction. S Even when the vehicle body tilt angle θ is set to θ , the radar device 1 transmits a transmission wave from the horizontal direction toward the vehicle upper side D2a. car It is written as follows.

[0119] For example, as shown in FIGS. 17 and 18, when the vehicle body tilt θ car Assume that the bumper angle θ is +3° at the time of shipment. B is 0°, and the radar angle θ R If the scan angle θ is set to +5°, S The radar angle θ R If the angle is set to +5°, which is equal to the horizontal angle, the transmission angle of the transmission wave is inclined by +3° toward the vehicle upper D2a with respect to the horizontal direction.

[0120] Therefore, when the body of the vehicle C is tilted with respect to the horizontal direction, the control circuit 20 of the radar device 1 of this embodiment adjusts the scan angle θ so that the beam angle of the transmission wave approaches a direction along the horizontal direction. S For example, adjust the vehicle body inclination θ car is +3°, the control circuit 20 adjusts the scan angle θ so that the beam angle of the transmission wave is aligned along the horizontal direction. S , radar angle θ R +5° to the vehicle body tilt θ car The beam angle can be readjusted by subtracting +3° from the original value and setting it to +2°.

[0121] In this case, the bumper B is tilted by -3° (=0°-3°) relative to the ground, and the radar device 1 is tilted by 2° (=5°-3°). In other words, the beam angle is adjusted to satisfy the relationship in Equation 2. Equation 2 is expressed as |θ B -θ R |=|-3°-2°|=5°, and θ in Equation 3 S =θ RIn this way, it is possible to take measures against reflection while simultaneously adjusting for the inclination of vehicle C.

[0122] The control circuit 20 can acquire information on the inclination of the body of the vehicle C relative to the horizontal direction from, for example, a leveler device (not shown) that adjusts the optical axis of the headlamp of the vehicle. Then, the control circuit 20 adjusts the scan angle θ based on the information acquired from the leveler device. S Adjust.

[0123] The control circuit 20 may acquire information on the inclination of the vehicle body of the vehicle C relative to the horizontal direction from an AFS (Adaptive Front-Lighting System) device (not shown) that the vehicle has. In this embodiment, the control circuit 20 functions as an inclination acquisition unit that acquires vehicle inclination that indicates the inclination of the vehicle C relative to the horizontal direction.

[0124] As described above, the radar device 1 of this embodiment includes an antenna board 10 provided facing the bumper B, and having an antenna surface 11 on which are arranged the transmitting antenna array 70 that transmits radio waves toward the bumper B and the receiving antenna array 80 that receives radio waves reflected by a target and passed through the bumper B. The radar device 1 further includes a phase shifter 42 that changes the beam angle of the transmission waves, which are radio waves transmitted by the transmitting antenna array 70, and a control circuit 20 that controls the phase shifter 42 to adjust the beam angle. The antenna board 10 is arranged so that the antenna surface 11 is inclined with respect to the vehicle up-down direction D2, which is the vertical direction, and at an angle such that the antenna surface 11 is not parallel to the inner surface B1 of the bumper B. The control circuit 20 controls the scanning angle θ S is the radar angle θ R Adjust the beam angle so that it approaches

[0125] According to this, by arranging the transmitting antenna array 70 and the receiving antenna array 80 in an array, positioning the antenna substrate 10 at an angle with respect to the bumper B, and emitting radio waves while shifting the phase of each antenna array 70, 80 by controlling the beam angle with the control circuit 20, it is possible to reduce the influence of reflection from the bumper B. Furthermore, even if a part of the reflected wave reflected from the radar device 1 is reflected again by the inner surface B1 of the bumper B, the traveling direction of this reflected wave will be toward the vehicle upper side D2a or the vehicle lower side D2b with respect to the vehicle fore-and-aft direction D1. Therefore, multiple reflection, in which the reflected wave is reflected multiple times between the bumper B and the radar device 1, is unlikely to occur.

[0126] Therefore, the reflected waves reflected by the inner surface B1 of the bumper B do not interfere with the transmitted and received waves of the antenna arrays 70, 80 simultaneously, and furthermore, can be physically dispersed outside the reception range of the radar device 1, thereby suppressing the influence of the reflected waves reflected by the bumper B. Furthermore, regardless of the shape of the bumper B, the influence of multiple reflections can be suppressed by tilting the antenna substrate 10 of the radar device 1, so that the influence of radio waves reflected by the bumper B can be suppressed without restricting the shape of the bumper B.

[0127] Furthermore, when the receiving antenna array 80 of the radar device 1 has a plurality of receiving elements 81, the plurality of receiving elements 81 can be separated from the equiphase surface, and therefore it is possible to stagger the reception timing of the reflected wave from the inner surface B1 received by each of the plurality of receiving elements 81. Therefore, even when each of the plurality of receiving elements 81 receives a reflected wave in which a reflected wave reflected from a target and a reflected wave reflected from the inner surface B1 of the bumper B overlap, it is possible to reduce the influence of the overlapped reflected waves.

[0128] Furthermore, according to the above embodiment, the following effects can be obtained.

[0129] (1) In the above embodiment, the control circuit 20 controls the scan angle θ S is the radar angle θ R Adjust the beam angle so that it is equal to

[0130] This allows the radar device 1 to transmit a transmission wave toward the front D1a of the vehicle even when the radar device 1 is disposed so that the antenna surface 11 is inclined with respect to the vehicle up-down direction D2.

[0131] (2) In the above embodiment, the radar angle θ R is set to an angle in the range of 3° or more and less than 10°.

[0132] As mentioned above, the radar angle θ R If the radar angle θ is set to an angle in the range of 3° or more and less than 6°, a relatively large received signal can be obtained while reducing the ripple. R When the range is set to be greater than 7°, the radar angle θ R As the value of is increased, the signal strength tends to decrease.

[0133] Therefore, the radar angle θ R By setting the angle within a range of 3° or more and less than 10°, the radar device 1 can obtain a relatively large received signal while reducing the ripple.

[0134] (3) In the above embodiment, the control circuit 20 electronically adjusts the beam angle of the transmission wave.

[0135] This makes it easier to adjust the beam angle of the transmission wave to any angle than when the radar device 1 is configured to mechanically control the beam angle of the transmission wave using, for example, a DIP switch. S and radar angle θ R When adjusting the beam angle so that the radar angle θ is equal to the R Not limited to scan angle θ S The radar angle θ R can be adjusted to an equal angle.

[0136] (4) In the above embodiment, the transmitting antenna array 70 is configured as a phased array antenna in which a plurality of transmitting-on elements 71a, 71c, each of which transmits radio waves, are arranged side by side on the antenna surface 11. The control circuit 20 adjusts the beam angle by controlling the phase of the radio waves transmitted by each of the plurality of transmitting-on elements 71a, 71c.

[0137] In this embodiment, in which the transmitting antenna array 70 is configured as a phased array antenna, when transmitting a transmission wave toward the front D1a of the vehicle, the narrow beam makes it difficult for the transmission wave to spread in the vehicle vertical direction D2 and the vehicle horizontal direction D3. Therefore, when transmitting a transmission wave toward the front D1a of the vehicle, the radar device 1 can transmit the transmission wave to a target that is located farther away, and can acquire information about the target that is located farther away.

[0138] Furthermore, according to this embodiment in which the transmitting antenna array 70 is configured as a phased array antenna, the scan angle θ S When adjusting the scan angle θ, the fine angle is set in units of less than 1°. S can be adjusted.

[0139] (5) In the above embodiment, the receiving antenna array 80 is configured as a phased array antenna in which a plurality of receiving elements 81a, 81c, each of which receives a reflected wave, are arranged side by side on the antenna surface 11.

[0140] This makes it easier to limit the reception range in the vehicle vertical direction D2 and the vehicle horizontal direction D3 when the receiving antenna array 80 receives reflected waves. Therefore, it becomes more difficult for the radar device 1 to receive reflected waves from the inner surface B1 of the bumper B, and the influence of receiving reflected waves reflected by the bumper B can be suppressed.

[0141] (6) In the above embodiment, the transmitting antenna array 70 and the receiving antenna array 80 are arranged side by side on the antenna plane 11 in a direction different from the vehicle up-down direction D2, which is the vertical direction.

[0142] If the transmitting antenna array 70 and the receiving antenna array 80 are arranged side by side in the vehicle up-down direction D2 on the antenna surface 11, the receiving antenna array 80 will be more likely to receive the reflected waves that are reflected by the bumper B and travel horizontally above the vehicle D2a or below the vehicle D2b. This makes the radar device 1 more susceptible to the influence of receiving the reflected waves reflected by the bumper B.

[0143] In contrast, according to this embodiment, in which the transmitting antenna array 70 and the receiving antenna array 80 are arranged side by side on the antenna plane 11 in a direction different from the vehicle up-down direction D2, the receiving antenna array 80 is less likely to receive the reflected waves reflected by the bumper B. Therefore, the radar device 1 is less susceptible to the influence of receiving the reflected waves reflected by the bumper B.

[0144] (7) In the above embodiment, the radar device 1 is applied to a vehicle C and includes a control circuit 20 that acquires the tilt of the vehicle C with respect to the horizontal direction. When the vehicle C is tilted with respect to the horizontal direction, the control circuit 20 adjusts the scan angle θ so that the beam angle approaches a direction along the horizontal direction. S Adjust.

[0145] As described above, the vehicle C may be tilted relative to the horizontal direction. For this reason, the scan angle θ is set to the same angle as when the vehicle C is not tilted relative to the horizontal direction. S When this is set, the radar device 1 is unable to transmit the transmission wave to the front D1a of the vehicle.

[0146] On the other hand, even if the vehicle C is tilted with respect to the horizontal direction, the scan angle θ is set so that the beam angle approaches the horizontal direction. S By adjusting the angle, the radar device 1 can transmit the transmission wave to the front D1a of the vehicle.

[0147] (Second embodiment) Next, a second embodiment will be described with reference to Fig. 19. In this embodiment, the bumper angle θ B , radar angle θ Rand scan angle θ S The second embodiment differs from the first embodiment in the points mentioned above. Other than this, the second embodiment is similar to the first embodiment. Therefore, in this embodiment, the differences from the first embodiment will be mainly described, and the description of the same parts as the first embodiment may be omitted.

[0148] In the radar device 1 of this embodiment, similarly to the first embodiment, the bumper angle θ is set so as to satisfy all of the above formulas 1 to 3. B , radar angle θ R and scan angle θ S However, unlike the first embodiment, the radar device 1 of this embodiment does not change the bumper angle θ B 19, the radar device 1 of this embodiment is applied to a host vehicle having a bumper B whose angle is different from 0°. B In this case, the radar device 1 of the present embodiment calculates the radar angle θ based on Equation 2. R is positioned on the vehicle so that the angle is +1° or -9°.

[0149] Here, the radar angle θ R The closer the angle is to 0°, the greater the received strength of the reflected wave is likely to be. R is set at +1°.

[0150] The control circuit 20 of this embodiment adjusts the beam angle so as to satisfy the above formula 3. That is, the control circuit 20 adjusts the beam angle θ as shown in FIG. S is the radar angle θ R The beam angle of the transmission wave is adjusted to +1°, which is equal to the angle of the beam angle of the radar device 1. As a result, the beam angle of the transmission wave transmitted by the radar device 1 is set to a direction parallel to the horizontal direction and along the direction D1a ahead of the vehicle.

[0151] Other configurations are the same as those of the first embodiment. The radar device 1 of this embodiment can obtain the same effects as those of the first embodiment, which are achieved by a configuration similar to or equivalent to that of the first embodiment.

[0152] Furthermore, even when applied to a vehicle C having a bumper B whose inner surface B1 has a shape other than one that follows the vehicle's vertical direction D2, the influence of radio waves reflected by the bumper B can be suppressed without being limited by the shape of the bumper B.

[0153] (Other embodiments) Representative embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments and can be modified in various ways, for example, as follows.

[0154] In the above embodiment, the control circuit 20 controls the scan angle θ S is the radar angle θ R In the above example, the beam angle is adjusted to be equal to the angle, but the present invention is not limited to this.

[0155] Scan angle θ S is the radar angle θ R If the beam angle is adjusted to approach the scan angle θ S is the radar angle θ R The beam angle may be adjusted to a different angle.

[0156] In the above-described embodiment, an example was described in which the transmitting antenna array 70 and the receiving antenna array 80 are arranged side by side on the antenna surface 11 in a direction different from the vertical direction D2 of the vehicle, but this is not limited to this.

[0157] For example, the transmitting antenna array 70 and the receiving antenna array 80 may be arranged side by side on the antenna plane 11 in the vertical direction D2 of the vehicle, which is the vertical direction.

[0158] In the above embodiment, the radar device 1 is applied to the vehicle C, and an example is described in which various targets existing around the vehicle C are detected, but the present invention is not limited to this.

[0159] The radar device 1 of the present disclosure may be configured to be installed on equipment or objects other than the vehicle C, and to detect various targets existing around the various equipment or objects on which the radar device 1 is installed.

[0160] In the above-described embodiment, when the vehicle C is tilted with respect to the horizontal direction, the control circuit 20 adjusts the scan angle θ so that the beam angle of the transmission wave approaches a direction along the horizontal direction. S However, the present invention is not limited to this.

[0161] For example, the radar device 1 does not include a means for acquiring information about the inclination of the vehicle C relative to the horizontal direction, and does not change the scan angle θ S It may be configured not to adjust.

[0162] In the above-described embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential unless they are specifically stated as essential or are clearly considered essential in principle.

[0163] In the above-described embodiments, when numerical values ​​such as the number, values, amounts, ranges, etc. of components of the embodiments are mentioned, they are not limited to the specific numbers unless they are expressly stated as being essential or are clearly limited to a specific number in principle.

[0164] In the above-described embodiments, when referring to the shapes, positional relationships, etc. of components, etc., the shapes, positional relationships, etc. are not limited to those unless otherwise specified or when they are fundamentally limited to specific shapes, positional relationships, etc.

[0165] The control circuit 20 and methods of the present disclosure may be implemented in a special purpose computer by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. The control circuit 20 and methods of the present disclosure may be implemented in a special purpose computer by configuring a processor with one or more dedicated hardware logic circuits. The control circuit 20 and methods of the present disclosure may be implemented in one or more special purpose computers configured with a processor and memory programmed to perform one or more functions in combination with a processor configured with one or more hardware logic circuits. The computer program may also be stored as instructions executed by a computer on a computer-readable non-transitory storage medium. [Explanation of symbols]

[0166] 10 Antenna board 11 Antenna surface 20 Control circuit 42 Phase shifter 70 Transmitting Antenna Array 80 receiving antenna array B Cover material B1 Antenna facing surface θ S Scan Angle θ R Radar Angle

Claims

1. A radar device that transmits and receives radio waves through a cover member (B), an antenna substrate (10) provided opposite the cover member, the antenna substrate having an antenna surface (11) on which a transmitting antenna (70) that transmits the radio waves through the cover member and a receiving antenna (80) that receives the radio waves reflected by a target and transmitted through the cover member are arranged; a phase shifter (42) that changes a beam angle, which is the transmission direction of the radio wave transmitted by the transmitting antenna; a control circuit (20) for controlling the phase shifter to adjust the beam angle; the antenna substrate is disposed such that the antenna surface is inclined with respect to the vertical direction and is not parallel to an antenna-facing surface (B1) of the cover member that faces the antenna surface, The control circuit determines the angle formed by the direction perpendicular to the antenna surface and the direction along the beam angle as a scan angle (θ Ｓ ), and the angle formed by the vertical direction and the antenna plane is the radar angle (θ Ｒ ) and adjusts the beam angle so that the scan angle approaches the radar angle.

2. The radar device according to claim 1 , wherein the control circuit adjusts the beam angle so that the scan angle is equal to the radar angle.

3. 3. The radar device according to claim 2, wherein the radar angle is set to an angle within a range of 3 degrees or more and less than 10 degrees.

4. 2. The radar device according to claim 1, wherein the control circuit electronically adjusts the beam angle.

5. The transmitting antenna is configured as a phased array antenna in which a plurality of transmitting elements (71a, 71c) for transmitting the radio waves are arranged side by side on the antenna surface, The radar device according to claim 4 , wherein the control circuit adjusts the beam angle by controlling the phase of the radio waves transmitted by each of the plurality of transmitting elements.

6. 2. The radar device according to claim 1, wherein the receiving antenna is configured as a phased array antenna in which a plurality of receiving elements (81a, 81c) for receiving the radio waves are arranged side by side on the antenna surface.

7. The radar device according to claim 1 , wherein the transmitting antenna and the receiving antenna are arranged side by side in a direction different from the vertical direction on the antenna plane.

8. The radar device is applied to a vehicle (C), a tilt acquisition unit (20) for acquiring a vehicle tilt indicating a tilt of the vehicle relative to a horizontal direction, 8. The radar device according to claim 1, wherein, when the vehicle tilt acquired by the tilt acquisition unit is tilted with respect to a horizontal direction, the control circuit adjusts the scan angle so that a direction along the beam angle approaches a direction along a horizontal direction.

Images