Device for adjusting and testing a radar sensor

Abstract

Device for adjusting and testing a radar sensor (2) attached to a motor vehicle (1), with a reflector (3), characterized in that a tunnel-like absorber (4) is arranged between the radar sensor (2) and the reflector (3) such that a beam path of the radar sensor (2) is surrounded by the absorber (4).

Description

[0001] The invention relates to a device for adjusting and testing a radar sensor according to the preamble of claim 1.

[0002] Such radar sensors are installed in motor vehicles to implement driver assistance systems such as distance warnings or adaptive cruise control (ACC). After installation, these sensors must be adjusted in their installation position and checked for proper function.

[0003] For alignment, it is known, for example, to attach a device to the radar sensor that directs a defined light beam toward a marked object or light box, or reflects the light beam, so that any misalignment can be corrected. The disadvantage of this is that the space in front of the radar sensor, i.e., between it and the object or light box, must be clear for the unobstructed passage of the light beam. Trim elements or, for example, a bumper may only be installed after alignment.

[0004] Another known method for alignment is to place a suitable mirror in the radar sensor's beam path. The mirror is aligned several times in such a way that a radar beam is reflected back parallel to itself. Such an alignment is only applicable to multi-beam radar sensors with highly focused antennas and requires a relatively high level of effort.

[0005] It is also known to position a mirror near the radar sensor for alignment so that the radar beams are deflected approximately vertically upwards. A reflector is positioned vertically above the mirror to reflect the radar beams. The disadvantage of this alignment is that in the case of weaker radar beams and / or at relatively low frequencies, indirect beams can lead to errors.

[0006] Document DE 197 07 590 A1 discloses both a method and a device for adjusting the alignment of a distance sensor's beam characteristics. A target object in the form of a reflector is used for this purpose. The reflector is surrounded by an absorbing material. The absorbing material is not designed as a tunnel-like absorber and is therefore not suitable for absorbing indirect rays.

[0007] DE 60212468T2 describes a method and apparatus for adjusting a radar mounting arrangement in a vehicle. Two absorbers are arranged above and below a line connecting the radar and a reflector: this setup is relatively complex and requires a lot of space.

[0008] Based on the known examples, the object of the invention is to provide a device for adjusting and testing a radar sensor which is suitable for all radar sensors.

[0009] The problem is solved by the features of claim 1. A beam path of the radar sensor is surrounded by a tunnel-shaped absorber. This largely absorbs indirect rays, which could lead to errors in the adjustment and testing of the radar sensor. Indirect rays are defined here as rays that deviate significantly from the focus of a main beam and, without absorbers, would be reflected by obstacles such as the ground or objects to the side. Due to the absorption of indirect rays, the device according to the invention can also be successfully used for radar sensors with a relatively low frequency of 1 to 40 GHz; particularly in the lower part of this frequency range, the indirect radiation is relatively high and, without absorption, would lead to intolerable errors. The device according to the invention can therefore be used for radar sensors regardless of their frequency.

[0010] The use of a mirror that deflects the beams by 90° enables the device to be used even in confined spaces, because part of the required measuring section is moved vertically.

[0011] A solid casing around the absorber makes it insensitive to external mechanical influences, so that the device can be used well in production operations, e.g. on a motor vehicle assembly line.

[0012] Specially treated foam is particularly suitable as an absorber material.

[0013] A Doppler simulator has proven particularly useful as a reflector for the adjustment and functional testing of radar sensors.

[0014] The invention is explained in more detail below with reference to the accompanying drawings. In the drawings: Fig. 1 a vertical section through a device according to the invention arranged in front of a motor vehicle, and Fig. 2 a vertical section through a preferred embodiment of the device with mirror.

[0015] Fig. 1 shows a motor vehicle 1, in the front of which a radar sensor 2 is mounted. The radar sensor 2 is aligned such that, during operation, its beams 7 are directed in the direction of travel. In front of the motor vehicle, a device according to the invention for adjusting and testing the radar sensor 2 is movably arranged on a frame (not shown). The device comprises a reflector 3, which is held in front of the radar sensor 2 in the beam path at a specific distance range of, for example, (3 ± 0.2) m as a measuring section. This means that the reflector 3 is at the same height as the radar sensor 2, within a specific tolerance.

[0016] A tunnel-like absorber 4 is arranged between the radar sensor 2 and the reflector 3. The absorber 4 is designed as a cuboid housing with a square cross-section; it is closed on five sides, with an open sixth side facing the radar sensor. The reflector 3 forms a central part of a side opposite the sixth side. The absorber 4 is surrounded by a rigid casing 5. For this purpose, the absorber 4 is covered on its outer sides, e.g., with a sheet metal or another rigid, stable material.

[0017] Absorber 4 is made of radar-absorbing material, such as specially treated foam. This foam is known per se and impregnated with an unknown liquid.

[0018] The reflector is preferably a Doppler simulator according to DE 10 2005 032 649 A1, the disclosure content of which is expressly part of this invention.

[0019] The example after the Fig. 2 differs from the one described above in the following ways: The absorber 4 has the shape of a mirror-inverted L. A mirror 6 is arranged in the beam path of the radar sensor 2. The mirror 6 is mounted behind the sixth side of the absorber 4 in the radiation direction of the radar sensor 2 in such a way that it rises from the horizontal at an angle of 45° in the radiation direction, thus deflecting the beam 7 upwards by 90° during operation. The absorber 4 is accordingly guided upwards at a right angle. A corresponding part of the absorber 4 and the casing 5 is replaced by the mirror 6, and the corresponding corner is chamfered.

[0020] The measuring distance is (3 ± 0.2) m, as in the first example, with approximately one fifth to one third being horizontal and the rest being vertical.

[0021] During operation, for example, on a motor vehicle assembly line, the device for adjusting and testing radar sensor 2 is positioned in front of it for testing and adjustment, and radar sensor 2 is switched on. This emits beam 7, which is reflected by reflector 3 and received by radar sensor 2.

[0022] Any indirect rays that may arise are absorbed by the absorber 4 at least to the extent that they are harmless for the adjustment and testing. If the test reveals incorrect measurements of the radar sensor 2, it is adjusted mechanically and / or electronically. If necessary, the test is repeated. Once the radar sensor 2 is adjusted, the device is moved away, and the motor vehicle is moved according to the predetermined installation plan.

Claims

[1] Device for adjusting and testing a radar sensor (2) attached to a motor vehicle (1), with a reflector (3), characterized by that a tunnel-like absorber (4) is arranged between the radar sensor (2) and the reflector (3) in such a way that a beam path of the radar sensor (2) is surrounded by the absorber (4). [2] Device according to claim 1, characterized by that a mirror (6) is arranged in the beam path such that a beam (7) emanating from the radar sensor (2) and reflected by the reflector (3) is deflected by 90°. [3] Device according to claim 1 or 2, characterized by that the absorber (4) is surrounded on the outside by a solid jacket (5). [4] Device according to one of claims 1 to 3, characterized by that the absorber (4) is made of specially treated foam. [5] Device according to one of claims 1 to 3, characterized by that the reflector (3) is a Doppler simulator.

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