JP2021038984A - Structure with radar device and bracket - Google Patents

Abstract

To improve directional characteristics of a rader device.SOLUTION: As a structure (plate-shaped members 21, 22) arranged in the vicinity of a radar device 10 that transmits and receives radio waves of a predetermined frequency and detects the position of a target in a first direction, one or more plate-like members 21,22 are located near the side surface of the radar device 10 in the first direction, and configured to reflect radio waves out of the field of view of the radar device in a second direction orthogonal to the first direction, with at least some of the surfaces tilted with respect to the first direction.SELECTED DRAWING: Figure 6

Description

The present invention relates to a structure to which a radar device is attached and a bracket.

Patent Document 1 discloses a technique for achieving a desired directivity by providing a wall portion in a radome of a radar device. More specifically, in the technique disclosed in Patent Document 1, the antenna portion that transmits and receives at least one of the radar waves is protected by the radome, and the facing surface of the radome facing the antenna portion is protected by the radome. A wall portion is provided that projects from the facing surface toward the formed radome space. The wall portion is formed so as to follow at least a part of the outer periphery of the aperture projection portion, with the portion where the antenna opening surface of the antenna portion is projected in the normal direction of the antenna opening surface with respect to the facing surface as the opening projection portion. There is.

Patent Document 2 discloses a technique of blocking radio waves radiated at a wide angle and radiating radio waves within a desired range due to the influence of a bumper of a vehicle in which a radar device is arranged. More specifically, in the technique disclosed in Patent Document 2, a radar device provided between the back surface of the bumper and the wheel, which detects an obstacle by transmitting radio waves through the bumper, and one of the transmitted waves. A false detection prevention member that prevents false detection of the radar device by suppressing the generation of the own wheel arrival wave that passes between the transmitter of the radar device and the back surface of the bumper and reaches the own wheel. The false detection prevention member is a shielding plate provided so as to block the path of the wave reaching the own wheel.

Japanese Unexamined Patent Publication No. 2014-020846 International Publication No. 2012-144150

By the way, the techniques disclosed in Patent Document 1 and Patent Document 2 have a problem that the directional characteristics are deteriorated because the reflected wave is generated in the wall portion or the shielding plate and the reflected wave enters the field of view of the radar device. There is.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a structure to which a radar device is attached and a bracket capable of improving the directivity of the radar device.

In order to solve the above problems, the present invention relates to a structure arranged in the vicinity of a radar device that transmits and receives radio waves of a predetermined frequency and detects the position of a target in the first direction. The second direction, which is arranged in the vicinity of the side surface in the first direction, has at least a part of the surfaces inclined with respect to the first direction, and is orthogonal to the first direction, is out of the field of view of the radar device. It is characterized by having one or more plate-like members configured to reflect radio waves.
With such a configuration, it is possible to improve the directivity of the radar device.

Further, the present invention is characterized in that the radar device is arranged in the vicinity of the radar device in which the viewing angle in the first direction is wider than the viewing angle in the second direction.
According to such a configuration, the radio wave can be reflected out of the field of view in the second direction with a simple configuration.

Further, the present invention is characterized in that the first direction is a direction in which the receiving antennas of the radar device are arranged in a row.
According to such a configuration, it is possible to prevent the angle from being indefinite by reflecting the radio wave in the direction orthogonal to the direction in which the position of the target is detected.

Further, the present invention is characterized in that the plate-shaped member is arranged so that a part of the plate-shaped member is located in the transmission direction of the radio wave with respect to the surface on which the receiving antenna of the radar device is arranged. ..
According to such a configuration, the occurrence of multipath can be reduced by reflecting the radio wave in the second direction.

Further, in the present invention, when a plurality of the plate-shaped members are arranged in a row at predetermined intervals and separated from each other and the wavelength of the radio wave is λ, the predetermined intervals are λ / 10 or more and 3λ / 2. It is characterized in that it is set as follows.
According to such a configuration, the occurrence of multipath can be reduced more reliably.

Further, the present invention is characterized in that the plurality of plate-shaped members have a thickness of λ'/8 or more when the effective wavelength of the radio wave in the plate-shaped member is λ'.
According to such a configuration, the linearity of the directivity characteristic can be improved.

Further, in the present invention, the plurality of plate-shaped members have a thickness of 3λ'/ 8 or more and 4.5λ' / 8 or less when the effective wavelength of the radio wave in the plate-shaped member is λ'. It is characterized by that.
According to such a configuration, the linearity of the directivity characteristic can be further improved.

Further, in the present invention, the plurality of plate-shaped members have a thickness of 3.5λ'/ 8 or more and λ'/2 or less when the effective wavelength of the radio wave in the plate-shaped member is λ'. It is characterized by that.
According to such a configuration, the occurrence of ambiguity can be reduced.

The plurality of plate-shaped members are characterized in that they have an inclination of 5 degrees or more and 80 degrees or less with respect to the first direction.
According to such a configuration, the linearity of the directivity characteristic can be improved.

Further, the present invention is characterized in that the plurality of plate-shaped members have an inclination of 40 degrees or more and 50 degrees or less with respect to the first direction.
According to such a configuration, the occurrence of ambiguity can be reduced.

Further, in the present invention, the plurality of the plate-shaped members are arranged in a row separated from each other at a predetermined interval, and the receiving antenna of the radar device is arranged on the surface having an inclination with respect to the first direction. It is characterized in that it is configured to be substantially perpendicular to the surface.
According to such a configuration, the occurrence of multipath can be reduced more reliably.

Further, in the present invention, the plurality of the plate-shaped members are arranged in a row separated from each other at a predetermined interval, and the predetermined interval is the said with respect to a change in the position where the target is present in the first direction. It is characterized in that the rate of change in the position detected by the radar device is set to be monotonous.
According to such a configuration, it is possible to prevent the angle from being indefinite.

Further, in the present invention, the plurality of the plate-shaped members are arranged in a row so as to be separated from each other at a predetermined interval, and the plurality of the plate-shaped members are arranged in a row so as to overlap each other in the first and second directions. It is characterized by being.
According to such a configuration, the occurrence of multipath can be more reliably reduced by reliably reflecting radio waves.

Further, the present invention is characterized in that the plate-shaped member further has another surface having an inclination with respect to the part of the surface.
According to such a configuration, the occurrence of multipath can be more reliably reduced by reflecting radio waves in a plurality of directions.

Further, the present invention is characterized in that the plate-shaped member is made of a dielectric material.
According to such a configuration, the manufacturing cost can be reduced.

Further, the present invention is characterized in that the plate-shaped member is composed of a member that absorbs the radio wave.
According to such a configuration, the occurrence of multipath can be more reliably reduced by absorbing radio waves.

Further, in the present invention, in the radar device, in a space sandwiched between a resin member and a metal member, the detection surface of the radar device faces the resin member, and the back surface located on the back side of the detection surface is said. It is characterized in that it is arranged so as to face the metal member.
According to such a configuration, it is possible to more reliably reduce the occurrence of multipath caused by the resin member and the metal member.

Further, the present invention is characterized in that the metal member is a body or chassis of a vehicle, and the resin member is a bumper of the vehicle.
According to such a configuration, when the radar device is mounted on the vehicle, the occurrence of multipath can be reduced more reliably.

Further, the present invention is characterized in that the radar device is arranged in the vicinity of the radar device mounted on the vehicle and the first direction is a substantially horizontal direction.
With such a configuration, the horizontal position of the target can be accurately detected.

Further, according to the present invention, in a bracket for attaching a radar device that transmits and receives radio waves of a predetermined frequency and detects the position of a target in the first direction to an object, the vicinity of the side surface of the radar device in the first direction. Is arranged so that at least a part of the surfaces have an inclination with respect to the first direction and reflect the radio wave out of the field of view of the radar device in the second direction orthogonal to the first direction. It is characterized by having one or more plate-shaped members.
With such a configuration, it is possible to improve the directivity of the radar device.

According to the present invention, it is possible to provide a structure and a bracket to which a radar device capable of improving the angular characteristics of the radar is attached.

It is a figure which shows the structural example of the vehicle which concerns on embodiment of this invention. It is a perspective view which shows the structural example of the radar apparatus shown in FIG. It is a figure which shows the beam shape of the radar apparatus shown in FIG. It is a figure which shows the positional relationship of the radar apparatus, a bumper, a body, and a plate-shaped member in embodiment of this invention. It is a figure which shows the positional relationship of the radar apparatus and a plate-shaped member in embodiment of this invention. It is a perspective view which shows the positional relationship of the radar apparatus and a plate-shaped member in embodiment of this invention. This is an example of arrangement of a transmitting antenna and a receiving antenna. It is a figure explaining the multipath when the plate-shaped member is not arranged. It is a figure which shows the correspondence relationship between the angle estimated by the radar apparatus shown in FIG. 2 and the actual angle. It is a figure which shows the directivity characteristic in the case of a single radar device, the case of having a resin cover, and the case of the prior art. It is a figure which shows the minimum inclination at the time of having a resin cover in the case of a radar apparatus alone. It is a figure which shows the directivity characteristic in the case of a single radar device, the case of having a resin cover, and the case of this embodiment. It is a figure which shows the relationship between the interval of a plate-shaped member, and the minimum inclination. It is a figure which shows the other structural example of a plate-shaped member. It is a figure which shows the other structural example of a plate-shaped member. It is a figure which shows the embodiment which arranged the plate-shaped member in a bracket. It is a figure which shows the embodiment which arranged the plate-shaped member in a bracket. It is a figure which shows the other arrangement example of a transmitting antenna and a receiving antenna. It is a figure which shows the other structural example of a plate-shaped member. It is a figure which shows the relationship between the thickness of a plate-shaped member, and the minimum inclination. It is a figure which shows the relationship between the inclination of a plate-shaped member, and the minimum inclination. It is a figure which shows the relationship between the thickness of a plate-shaped member, and the standard deviation of inclination. It is a figure which shows the relationship between the inclination of a plate-shaped member, and the standard deviation of an inclination.

Next, an embodiment of the present invention will be described.

(A) Explanation of Embodiments of the Present Invention FIG. 1 is a diagram showing a vehicle according to an embodiment of the present invention. FIG. 1A is a view of the vehicle 1 to which the radar devices 10-1 and 10-2 are attached from above, and FIG. 1B is a view of the vehicle 1 from the left. As shown in FIG. 1A, the two radar devices 10-1 and 10-2 are arranged on both sides in the bumper 2 at the rear of the vehicle 1. The radar devices 10-1 and 10-2 transmit radio waves toward the rear of the vehicle 1, receive the reflected waves reflected by the target of the following vehicle, and detect the distance, angle, speed, etc. to the target. To do. For example, the range of E1 and E2 is the reception field of view range of the radar. Further, as shown in FIG. 1 (B), the radar devices 10-1 and 10-2 are arranged inside the bumper 2 made of resin or the like. In this proposal, since it is related to the angular characteristics of the received signal, we focus on the reception characteristics of the radar device.

FIG. 2 is a perspective view of the radar devices 10-1 and 10-2 shown in FIG. The radar devices 10-1 and 10-2 each include a flat substrate and are formed in a shape based on a rectangular parallelepiped. Since the radar devices 10-1 and 10-2 have the same or similar configurations, they will be described below as the radar device 10. Further, the reception fields of view E1 and E2 of the radar devices 10-1 and 10-2 will be described as the reception field of view E. As shown in FIG. 2, the radar device 10 has a detection surface 11 which is a surface on the field of view side, and a back surface 12 which is arranged on the back side of the detection surface 11. In FIG. 2, the X direction corresponds to the left-right direction of the radar device 10, the Y direction corresponds to the front-rear direction of the radar device 10, and the Z direction corresponds to the vertical direction of the radar device 10. Further, in FIG. 2, the broken line schematically shows the shape of the reception field of view E assuming a distance from the radar device 10. The reception field of view E has a shape having a wide width in the XY plane direction, which is the horizontal direction of the vehicle, and a narrow width in the YZ plane direction, which is the vertical direction of the vehicle. The viewing angle of the XY plane of the radar device 10 is 2β, and the viewing angle of the YZ plane is 2α (α <β). Further, here, the direction of the center of the visual field is A.

FIG. 3 is a diagram showing an example of the received beam pattern of the radar device 10 shown in FIG. The horizontal axis of FIG. 3 indicates the angle from the visual field center direction A on the YZ plane shown in FIG. 2 (the angle in the vertical direction of FIG. 2), and the vertical axis indicates the antenna gain (dBi). Here, when the antenna omnidirectional 0 dBi is used as an index to the extent that the beam pattern width does not have sufficient intensity, and the angle at which the gain of the received main beam is 0 dBi or less is α, the example of FIG. Then, since the beam pattern is a beam in the range of negative 9 degrees to positive 9 degrees, 2α shown in FIG. 2 is approximately 18 degrees. For example, when detecting a target in the horizontal plane on the ground, on the road surface, or on the floor, the existence angle of the target is limited in the elevation plane as compared with the horizontal plane, so that a wide beam is not always necessary and the target is in the elevation plane. In, a beam pattern having a width as described above or a width around that width can be applied.

4 to 6 are views showing an installation example of the radar device 10. FIG. 4 is a view of the radar device 10 shown in FIG. 2 as viewed from the Z-axis direction. As shown in FIG. 4, the radar device 10 is arranged in the space sandwiched by the bumper 2 and the body 3. In the example of FIG. 4, the bumper 2 has a positional relationship with respect to the detection surface 11 of the radar device 10, and the body 3 has a positional relationship with respect to the back surface 12 of the radar device 10. In the example of FIG. 4, the bumper 2 is orthogonal to the field center direction A of the radar device 10. The bumper 2 is made of a resin member, and the body 3 is made of a metal member. Further, the radar device 10 is attached to the body 3 by an attachment member (not shown). Further, the body 3 may be, for example, a connecting component such as a bracket that is a connecting mechanism between the body 3 and the bumper 2 and the radar device 10, and the same effect will be exhibited in the following description.

As shown in FIGS. 5 and 6, a plurality of plate-shaped members 21 and 22 are arranged in the vicinity of the left and right side surfaces of the radar device 10 in the direction having the viewing angle of 2β (X direction) shown in FIG. There is. The plurality of plate-shaped members 21 are made of a resin (dielectric) having a length of L and a thickness of D. Further, the plurality of plate-shaped members 21 have an inclination of an angle θ with respect to the X direction, and each of the plate-shaped members 21 is arranged at a distance D. Similarly, the plurality of plate-shaped members 22 are also made of a resin having a length of L and a thickness of D. Further, the plurality of plate-shaped members 22 have an inclination of an angle θ with respect to the X direction, and are arranged so as to be orthogonal to the printed circuit board 15 at a distance D. As shown in FIG. 6, a part of the plate-shaped members 21 and 22 in the lateral direction is arranged so as to be located in front of the detection surface 11 of the radar device 10 in the Y direction. Further, the plate-shaped members 21 and 22 are arranged so that the plurality of plate-shaped members 21 and 22 overlap in the X direction, and the plurality of plate-shaped members 21 and 22 overlap in the Y direction as well.

FIG. 7 is a diagram showing a configuration example of an antenna built in the radar device 10 shown in FIG. As shown in FIG. 7, the radar device 10 is a transmission antenna in which a plurality of antenna elements having a rectangular shape are arranged at predetermined intervals in the Z direction on a printed circuit board 15 made of a dielectric material. 16-1 to 16-2 are arranged at both ends in the X direction. Further, between the transmitting antennas 16-1 to 16-2, the receiving antennas 17-1 to 17-4 formed by arranging a plurality of antenna elements having a rectangular shape at predetermined intervals in the Z direction are arranged. Has been done. In FIG. 7, the distance between the transmitting antennas 16-1 to 16-2 and the receiving antennas 17-1 to 17-4 in the X direction is d.

The radar device 10 uses a plurality of receiving antennas shown in FIG. 7 to measure the angle of the target by, for example, a monopulse method, a Fourier transform method, or an arrival angle estimation such as an eigenexpansion of a correlation matrix. More specifically, when the target exists in a certain angle direction, the radar device 10 calculates an identification value from the reception signal of the receiving antenna based on the various arrival angle estimation methods described above. The radar device 10 can derive a theoretical angle value from the identification value obtained by each method. When the theoretical angle value thus obtained is used as the estimated angle value, the angle measuring ability of the radar device 10 in a desired angle range is, for example, the horizontal axis as the target existence angle and the vertical axis as the estimated angle value. It can be defined by the angle table. In this angle table, it is desirable that the target presence angle and the estimated angle have a one-to-one correspondence and are completely linear. However, since there is actually some deviation, the radar device 10 removes the deviation by performing correction using the angle table. In this proposal, the above angle measurement is performed on the target on the XY plane including the substantially visual field center direction A.

By the way, when the radar device 10 is installed in a structure (vehicle 1) made of a plastic cover or a metal body, an unnecessary multipath is generated between the bumper 2 and the body 3 as shown in FIG. The characteristics may deteriorate. FIG. 9 is a diagram showing how the angular characteristics deteriorate. More specifically, the horizontal axis of FIG. 9 shows the actual angle θ of the target, and the vertical axis shows the angle θ'detected by the radar device 10. The solid line shows the characteristics before mounting on the vehicle 1, and the broken line shows the characteristics after mounting on the vehicle 1. The solid line showing the characteristics before mounting has a slope of about 1 and has the characteristics of a substantially straight line. On the other hand, the broken line showing the characteristics after mounting has some parts that deviate from the solid line, and is not a straight line but a meandering curve centered on the solid line. Therefore, when the radar device 10 is attached to the vehicle 1, the angle value estimated by the radar device 10 fluctuates, and this fluctuation amount causes an angle error.

Therefore, the "angle error" and the "minimum inclination" are obtained as indexes indicating such an error. Here, the angle error is taken as the average value of the angle error values in a predetermined angle range (for example, a range of −60 degrees to +60 degrees). Further, as the minimum inclination, the minimum value of the inclination of the angle table in a predetermined angle range (for example, a range of −60 degrees to +60 degrees) is acquired here. The angle error is preferably as small as possible, but in some cases it can be removed by correction. However, if the monotonous increase and linearity of the angle table cannot be ensured, the correction cannot be performed properly, and a region where the angle is indefinite may occur. More specifically, when monotonic increase cannot be ensured due to ripple, as in the region surrounded by an ellipse in FIG. 9, the angle is not uniquely determined, and a region called ambiguity in which the angle is indefinite occurs. It is important that the angle table is perfectly linear, that is, the slope is close to 1 so that the region of indefinite angle does not occur. In order to realize such a state, when the slope is a negative value, it indicates that ripple is generated, so that the "minimum slope" is preferably a positive value.

In the present embodiment, the radio waves transmitted from the radar device 10 are out of the field of view in the Z direction (outside the field of view of 2α in FIG. 2) by the plurality of plate-shaped members 21 and 22 as shown by the broken line arrows in FIG. By reflecting, the occurrence of the multipath shown in FIG. 8 is prevented.

FIG. 10 is disclosed in Patent Document 1 in the case of a single radar device 10 and in the presence of a resin cover (for example, a bumper or the like) and a metal member (for example, a body or the like) as shown in FIG. It is a figure which compares the directivity in the case of a configuration. In the configuration of Patent Document 1, the characteristics of the side lobes are suppressed with respect to the main lobes in the range of about −90 to +90 degrees, as compared with the case of a single substance and the case where a resin cover is present. However, in the configuration of Patent Document 1, ripple occurs in the characteristics in the main lobe (within the viewing angle).

FIG. 11 is a diagram showing the minimum inclination in the case of the radar device 10 alone and in the case where the resin cover and the metal member are present in the case shown in FIG. As shown in FIG. 11, when the radar device 10 is a single unit, the minimum inclination is positive, but when the resin cover is present, the minimum inclination is negative. Therefore, when the resin cover and the metal member are present, an angle detection error may occur.

FIG. 12 is a diagram comparing the directivity of the radar device 10 alone, the presence of the resin cover and the metal member, and the case of the present embodiment. In the case of the present embodiment, not only the characteristics of the side lobes are suppressed, but also the ripple in the main lobe (in the viewing angle) is suppressed as compared with the configuration of Patent Document 1. That is, in the present embodiment, it is possible to prevent the angle from being indefinite by reflecting the radio waves outside the viewing angle by the plurality of plate-shaped members 21 and 22.

FIG. 13 is a diagram showing the relationship between the distance between the plate-shaped members 21 and 22 and the minimum inclination. Note that FIG. 13A shows a case where the plate-shaped members 21 and 22 have a length L = 50 mm, and FIG. 13B shows a case where the plate-shaped members 21 and 22 have a length L = 20 mm.

As shown in FIG. 13A, when the length L of the plate-shaped members 21 and 22 is 50 mm, the distance d between the plate-shaped members 21 and 22 sets the wavelength of the radio wave transmitted by the radar device 10 to λ (for example, When it is 12.4 mm in the case of 24 GHz), the minimum inclination becomes positive in the case of approximately λ / 2 (= 6 mm) to 3λ / 2 (= 18 mm).

Further, as shown in FIG. 13B, when the length L of the plate-shaped members 21 and 22 is L = 20 mm, the distance d between the plate-shaped members 21 and 22 sets the wavelength of the radio wave transmitted by the radar device 10 to λ. When this is done, the minimum inclination becomes positive in the case of approximately λ / 10 (= 1 mm) to λ / 2 (= 6 mm).

As described above, according to the embodiment of the present invention, the radio waves transmitted from the radar device 10 are viewed by a plurality of plate-shaped members 21 and 22 in the Z direction as shown by the broken line arrows in FIG. By reflecting to the outside, the minimum inclination can be set to a positive value, so that it is possible to prevent the occurrence of a region called ambiguity in which the angle is indefinite.

(B) Description of Modified Embodiment The above embodiment is an example, and it goes without saying that the present invention is not limited to the cases described above. For example, in the example of FIG. 5, a linear member is used as the plate-shaped members 21 and 22, but for example, as shown in FIG. 14, plate-shaped members 21 and 22 having an L-shape are used. It may be. In the example of FIG. 14, a plurality of plate-shaped members 21 and 22 having an L-shape having a thickness of W bent at an angle θ (for example, 90 degrees) at substantially the center are formed on both side surfaces of the radar device 10 in the X direction. It is arranged at intervals D in the vicinity of. Even when a plurality of plate-shaped members 21 and 22 having such an L-shape are used, as shown in FIG. 6, radio waves traveling in the Y-axis direction are reflected outside the viewing angle 2α shown in FIG. It is possible to reduce multipath and reduce the occurrence of indefinite angle called ambiguity.

Further, as shown in FIG. 15, a plurality of plate-shaped members 21 and 22 having a thickness W refracted at an angle θ (90 degrees <θ <180 degrees) at a substantially center are substantially parallel to the X direction. It may be arranged so as to be spaced apart from each other. Even with such a configuration, as shown in FIG. 6, multipath is reduced by reflecting radio waves traveling in the Y-axis direction outside the viewing angle 2α shown in FIG. 2, and the angle is indefinite, which is called ambiguity. Occurrence can be reduced.

FIG. 16 shows a configuration example using the bracket 30 in which the plate-shaped members 21 and 22 are attached to the ends. More specifically, in the example shown in FIG. 16, the bracket 30 is composed of plate-shaped members whose both ends in the X direction are bent at right angles in the Y direction. A plurality of plate-shaped members 21 and 22 are attached to both ends of the bracket 30. The plate-shaped members 21 and 22 may have the configuration shown in FIGS. 5, 14, or 15. The bracket 30 may be made of the same material as the plate-shaped members 21 and 22, and may be integrally formed of these. Alternatively, these may be configured as separate members and joined with screws or an adhesive. Even with such a configuration, multipath can be reduced by reflecting radio waves traveling in the Y-axis direction outside the viewing angle 2α shown in FIG. 2, and the occurrence of indefinite angle called ambiguity can be reduced.

FIG. 17 shows another configuration example using the bracket 30. In the example of FIG. 17, the bracket 30 is composed of a plate-shaped member, and is bent at an angle θ (90 degrees <θ <180 degrees) at both end portions. Further, a plurality of plate-shaped members 21 and 22 having a trapezoidal shape are arranged at both ends of the bracket 30. The bracket 30 may be made of the same material as the plate-shaped members 21 and 22, and may be integrally formed of these. Alternatively, these may be configured as separate members and joined with screws or an adhesive. Even with such a configuration, multipath can be reduced by reflecting radio waves traveling in the Y-axis direction outside the viewing angle 2α shown in FIG. 2, and the occurrence of indefinite angle called ambiguity can be reduced.

Further, in the above embodiment, as shown in FIG. 7, the transmitting antennas 16-1 to 16-2 and the receiving antennas 17-1 to 17-4 are arranged side by side in a straight line at the same position in the X direction. However, for example, as shown in FIG. 18, the transmitting antennas 16-1 to 16-2 are arranged below the printed circuit board 15 in the Z direction, and the receiving antennas 17-1 to 17-4 are arranged in the Z direction of the printed circuit board 15. It may be arranged separately above. In the example of FIG. 18, the receiving antennas 17-1 to 17-4 are arranged at intervals d from each other. Further, the transmitting antennas 16-1 to 16-2 are arranged at intervals of 4 × d. Even when the transmitting antennas 16-1 to 16-2 and the receiving antennas 17-1 to 17-4 are arranged in this way, by arranging the plurality of plate-shaped members 21 and 22 in the Y-axis direction. By reflecting the traveling radio wave outside the viewing angle 2α shown in FIG. 2, multipath can be reduced and the occurrence of indefinite angle called ambiguity can be reduced. It is desirable that the plurality of plate-shaped members 21 and 22 are arranged in the vicinity of the receiving antennas 17-1 to 17-4.

Further, in the above embodiments, the plate-shaped members 21 and 22 are made to use members having a uniform thickness, but as shown in FIG. 19, plate-shaped members 21 and 22 having a wedge-shaped cross section are used. You may do so. More specifically, in the example of FIG. 19, a plurality of plate-shaped members 21 and 22 having a thickness of W and a tip angle of θ have a wedge tip portion close to the side surface of the radar device 10 in the X direction. They are arranged at intervals D so as to do so. By arranging a plurality of plate-shaped members 21 and 22 having such a shape, radio waves traveling in the Y-axis direction are reflected outside the viewing angle 2α shown in FIG. 2, thereby reducing multipath and ambiguity. It is possible to reduce the occurrence of indefinite angles called tees.

Further, as shown in FIG. 20, by changing the thickness of the plate-shaped members 21 and 22, the minimum inclination of the angle table changes. More specifically, in FIG. 20, the minimum inclination of the angle table when only the radar device is used (single unit), the characteristics when the plate-shaped members 21 and 22 are not provided (0 mm), and the polycarbonate plate-shaped members 21 and 22 When the thickness is changed between 1 mm and 8 mm (that is, the effective wavelength λ'is the value obtained by dividing the wavelength λ of the radio wave transmitted by the radar device 10 by the refractive index of the plate-shaped members 21 and 22). It shows the minimum inclination of the angle table (when the thickness of the shaped members 21 and 22 is changed between λ'/ 8 and λ'). The distance between the plate-shaped members 21 and 22 is 4.5 mm. In the example of FIG. 20, when the thicknesses of the plate-shaped members 21 and 22 are 3.5 mm and 4 mm, the minimum inclination is positive, so that the thickness is about 3.5 mm to 4 mm, that is, 3.5 λ'/8. It can be seen that a thickness of more than or less than λ'/2 is preferable.

Further, as shown in FIG. 21, the minimum inclination of the angle table is changed by changing the angles of the plate-shaped members 21 and 22. More specifically, in FIG. 21, the minimum inclination of the angle table in the case of only the radar device (single unit), the characteristics in the case of not having the plate-shaped members 21 and 22 (0 mm), and the polycarbonate plate-shaped members 21 and 22 It shows the minimum inclination of the angle table (0 to 90) when the angle (angle θ in FIG. 5) is changed from 0 degrees to 90 degrees. The distance between the plate-shaped members 21 and 22 is 4.5 mm. In the example of FIG. 21, since the minimum inclination is positive when the angle θ of the plate-shaped members 21 and 22 is 40 to 50 degrees, the angle θ of the plate-shaped members 21 and 22 is about 40 to 50 degrees. It turns out to be preferable.

In each of the above embodiments, a suitable configuration example is shown from the viewpoint of reducing the occurrence of indefinite angle called ambiguity, but even if indefinite angle occurs depending on the environment in which the radar device 10 is used. In some cases, the angle at which the angle is indefinite is outside the field of view of the radar device 10, or the angle range in which the indefinite angle occurs is narrow, and the angle error can be reduced by correction. As described above, when the angle indefiniteness is allowed to some extent, the directivity of the radar device 10 can be improved if the standard deviation representing the variation in the inclination of the angle table is small. Of course, in each of the above embodiments, if the standard deviation of the inclination of the angle table becomes small, the directivity characteristic of the radar device 10 can be further improved.

FIG. 22 shows the standard deviation of the tilt of the angle table in the same case as in FIG. In the example of FIG. 22, the standard deviation is improved when the plate-shaped members 21 and 22 are provided regardless of the thickness, as compared with the case where the plate-shaped members 21 and 22 are not provided (0 mm). From this, it is preferable to have the standard deviation regardless of the thickness of the plate-shaped members 21 and 22. If the wavelength in the plate-shaped members 21 and 22 is λ', it is effective when it has a thickness of λ'/ 8 or more, and it is characteristic when it is 3λ' / 8 or more and 4.5λ' / 8 or less. Above preferred.

FIG. 23 shows the standard deviation of the tilt of the angle table in the same case as in FIG. In the example of FIG. 23, the standard deviation is improved when the angle θ of the plate-shaped members 21 and 22 is between 5 degrees and 80 degrees as compared with the case where the plate-shaped members 21 and 22 are not provided (0 mm). Therefore, with respect to the standard deviation, the angle θ of the plate-shaped members 21 and 22 is preferably in the range of 5 degrees to 80 degrees in terms of characteristics.

Further, as the plate-shaped members 21 and 22, a member that absorbs radio waves may be used. For example, a member obtained by mixing carbon powder or the like with a dielectric material to increase the dielectric loss can be used.

In each of the above embodiments, the body 3 has been described as an example of the metal member, but the chassis may be made of metal instead of the body 3. Alternatively, the metal bracket (fixing member) for mounting the radar device 10 on the chassis, body 3, or bumper 2 may have the same configuration as the body 3 described above.

Further, instead of the body 3 which is a metal member, a member made of a dielectric material may be arranged on the back surface side of the radar device 10. Further, the plate-shaped members 21 and 22 may be attached to the dielectric material arranged on the back surface side.

Further, the form of the housing of the radar device 10 shown in FIG. 2 and the like is an example, and may have a form having a structure other than this. Even when the housings have different forms, the same effect as in the above case can be obtained by arranging the plurality of plate-shaped members 21 and 22.

Further, in each of the above embodiments, the vehicle 1 has been described as an example of the object to which the radar device 10 is attached, but the radar device 10 may be attached to other objects. Specifically, it may be attached to a structure such as a ship, an airplane, a utility pole, or a building. Further, the metal member on the back surface of the radar illustrated above may be not only the metal plate itself but also a member having a reflectance close to that of metal, for example, a member containing particles having a conductivity close to that of metal.

1 Vehicle 2 Bumper 3 Body 10 Radar device 11 Detection surface 12 Back side surface 15 Printed circuit board 16-1 to 16-2 Transmitting antenna 17-1 to 16-4 Receiving antenna 21 Plate-shaped member 22 Plate-shaped member 30 Bracket

Claims (20)

In a structure arranged in the vicinity of a radar device that transmits and receives radio waves of a predetermined frequency and detects the position of a target in the first direction.
The radar device is arranged in the vicinity of the side surface of the radar device in the first direction, and at least a part of the surfaces has an inclination with respect to the first direction and is orthogonal to the first direction. It has one or more plate-like members configured to reflect the radio waves outside the field of view.
A structure characterized by that. The structure according to claim 1, wherein the structure is arranged in the vicinity of the radar device having a wider viewing angle in the first direction than the viewing angle in the second direction. The structure according to claim 1 or 2, wherein the first direction is a direction in which the receiving antennas of the radar device are arranged in a row. The plate-shaped member according to any one of claims 1 to 3, wherein a part of the plate-shaped member is arranged so as to be located in the transmission direction of the radio wave with respect to the surface on which the receiving antenna of the radar device is arranged. The structure according to any one item. The plurality of plate-shaped members are arranged in a row at predetermined intervals so as to be separated from each other.
When the wavelength of the radio wave is λ, the predetermined intervals are set to λ / 10 or more and 3λ / 2 or less.
The structure according to any one of claims 1 to 4, wherein the structure is characterized by the above. The plurality of plate-shaped members have a thickness of λ'/8 or more, where λ'is the effective wavelength of the radio wave in the plate-shaped member.
The structure according to any one of claims 1 to 5, wherein the structure is characterized by the above. The plurality of plate-shaped members have a thickness of 3λ'/ 8 or more and 4.5λ' / 8 or less, where λ'is the effective wavelength of the radio wave in the plate-shaped member.
The structure according to claim 6. The plurality of plate-shaped members have a thickness of 3.5λ'/ 8 or more and λ'/2 or less, where λ'is the effective wavelength of the radio wave in the plate-shaped member.
The structure according to claim 7. The plurality of plate-shaped members have an inclination of 5 degrees or more and 80 degrees or less with respect to the first direction.
The structure according to any one of claims 1 to 8, wherein the structure is characterized by the above. The plurality of plate-shaped members have an inclination of 40 degrees or more and 50 degrees or less with respect to the first direction.
The structure according to claim 9. The plurality of plate-shaped members are arranged in a row at predetermined intervals and separated from each other.
The surface having an inclination with respect to the first direction is configured to be substantially perpendicular to the surface on which the receiving antenna of the radar device is arranged.
The structure according to any one of claims 3 to 5, wherein the structure is characterized by the above. The plurality of plate-shaped members are arranged in a row at predetermined intervals and separated from each other.
The predetermined interval is set so that the ratio of the change in the position detected by the radar device to the change in the position where the target is present in the first direction becomes monotonous.
The structure according to claim 11. The plurality of plate-shaped members are arranged in a row at predetermined intervals and separated from each other.
A plurality of the plate-shaped members are arranged in a row so as to overlap each other in the first and second directions.
The structure according to any one of claims 3 to 12, characterized in that. The structure according to any one of claims 1 to 13, wherein the plate-shaped member further has another surface having an inclination with respect to the part of the surface. The structure according to any one of claims 1 to 14, wherein the plate-shaped member is made of a dielectric material. The structure according to any one of claims 1 to 15, wherein the plate-shaped member is composed of a member that absorbs radio waves. In the radar device, the detection surface of the radar device faces the resin member and the back surface located on the back side of the detection surface faces the metal member in the space sandwiched between the resin member and the metal member. The structure according to any one of claims 1 to 16, wherein the structure is arranged in. The structure according to claim 17, wherein the metal member is a body or chassis of a vehicle, and the resin member is a bumper of the vehicle. It is placed in the vicinity of the radar device mounted on the vehicle and
The structure according to any one of claims 1 to 18, wherein the first direction is a substantially horizontal direction. In a bracket that attaches a radar device that transmits and receives radio waves of a predetermined frequency and detects the position of an object in the first direction to an object.
The radar device is arranged in the vicinity of the side surface of the radar device in the first direction, and at least a part of the surfaces has an inclination with respect to the first direction, and the radar device has a second direction orthogonal to the first direction. It has one or more plate-like members configured to reflect the radio waves outside the field of view.
Bracket featuring that.

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