Radar antenna arrangement for a vehicle comprising at least one vehicle component and vehicle

Abstract

The invention relates to a radar antenna arrangement (1) for a vehicle (2), comprising at least one vehicle component (3), wherein the radar antenna arrangement (1) has a plurality of radar devices (4) designed to transmit and / or receive radar beams (12). The radar devices (4) are arranged on a component surface (5) of the vehicle component (3). The invention provides that the radar antenna arrangement (1) has at least one antenna row (6) for determining an azimuth angle (10) of the radar beam (12), the at least one antenna row (6) comprising a plurality of radar devices (4). Directly adjacent radar devices (4) have a corresponding horizontal distance (8) from one another. The radar antenna arrangement (1) has at least one antenna column (7) for determining an elevation angle (11) of the radar beam (12), the at least one antenna column (7) comprising a plurality of radar devices (4). Directly adjacent radar devices (4) have a corresponding vertical distance (9) from one another. At least one antenna row (6) and at least one antenna column (7) enclose an angle α of 5 degrees to 180 degrees.

Description

Technical Field

[0001] The invention relates to a radar antenna arrangement for a vehicle comprising at least one vehicle component. The invention also covers a vehicle having a radar antenna arrangement and a method for calibrating a radar antenna arrangement. Background Art

[0002] In order to collect the surroundings of the vehicle, especially in the case of automated driving of the vehicle or when using demanding driver assistance systems, it is necessary to collect the entire surroundings of the vehicle by means of sensors, radar, lidar or cameras. Here, it is necessary to collect a 360-degree angular range around the vehicle, thereby collecting all static and dynamic objects. In addition to the direction, it is also important to determine the distance of the object. In this case, it is the so-called three-dimensional environment collection. In order to be able to achieve the required angular resolution, LIDAR sensors are used in particular for this purpose. The advantage of LIDAR sensors is that they combine distance measurement with high angular resolution. The problem with 360-degree collection of the vehicle's surroundings by lidar is that a large number of small independent sensors with their own light sources and collector elements are required. As an alternative to this, there are larger sensors, but these larger sensors have larger dimensions, which limits the choice of installation locations on the vehicle. This problem becomes particularly important when it is necessary to install it inconspicuously on the vehicle.

[0003] When processing the measurement data of individual LIDAR sensors, there is the problem that each LIDAR sensor must collect and process its measurement data individually. In a subsequent step, the processed measurement data must be fused for creating the environment. When fusing the individual measurement data, precise time stamps are particularly required for real-time processing. A disadvantage of using LIDAR sensors is that their accuracy and operability depend on the current visibility. In particular, the accuracy is affected in fog, snow or low light conditions. Similar problems arise with regard to visibility when using cameras to collect the surroundings. In contrast, collecting the surroundings by radar is not affected by visibility. A disadvantage of collecting the surroundings with the help of radar sensors is the provision of a suitable radar arrangement. Collecting the angular range with sufficient resolution requires the provision of cluster antennas with a sufficiently large area. Cluster antennas, also called antenna arrays, have a large number of individual sensors for transmitting and / or receiving radar beams. By setting or determining the phase relationship of the radar beams transmitted or received by the individual antennas, the direction of the radar beam to be transmitted or received can be determined. When evaluating the measurement data of radar sensors, the problem arises that the individual sensors must be synchronized with one another in order to be able to determine the phase differences between the individual received radar beams. A disadvantage of the known prior art is that radar arrangements have an angular separability in azimuth of 10 to 4 degrees. The angular separability in elevation is generally low, so that the imaging methods using radar data cannot achieve the accuracy required for autonomous vehicles. In contrast, the angular separability of LIDAR systems is in the range of 0.1 degrees.

[0004] Known radar sensors for vehicles according to the prior art have dimensions of approximately 10 cm×10 cm and allow a maximum angular resolution of approximately 2 degrees, without being able to achieve a three-dimensional environment collection. On the other hand, so-called nano-radars have dimensions in the range of 5 cm×5 cm and can be integrated into vehicles more easily due to their compact design. In order to increase the resolution capability, the so-called synthetic aperture method can be used to further increase the resolution. When evaluating the measurement data from the individual sensors, as in the case of LIDAR sensors, the problem of time synchronization arises. In order to merge the measurement data, the time stamps must match so that an overall image of the environment can be created. According to the current state of the art, the range of action of nano-radars is limited to approximately 45 m. The synthetic aperture method used can only be perpendicular to the direction of travel. With this method, predictions cannot be made in the direction of travel or in the opposite direction. In addition, the data processing required after the measurement is very computationally intensive. Generally, the problem arises that a large number of sensors are required and the radar arrangement, in order to provide the required accuracy, requires dimensions that can only be provided to a limited extent on the vehicle.

[0005] US 5682168 A discloses a hidden vehicle antenna. Here, it is provided that the antenna element is arranged below the cover above the roof rack or behind the front grille of the motor vehicle.

[0006] US 6118410A discloses a roof antenna tray arranged below a vehicle window. The vehicle window may be, for example, a front window or a rear window, which has a fixed structure for accommodating a large number of high-frequency antennas. The vehicle window has an elongated area that extends along the roof antenna tray to the top of the vehicle and forms an intermediate space. A plurality of antennas are arranged on the antenna tray in the intermediate space.

[0007] US 2014 / 0354462 A1 discloses a radar device for being arranged behind a front window. It is provided that the front window has a metal layer to prevent the propagation of infrared rays and radar radiation through the front window. The metal layer forms an opening so that the radar device can send and collect radar signals. The antenna of the radar device is arranged behind the front window and faces the opening. Summary of the invention

[0008] The object of the present invention is to enable the detection of the surroundings with greater accuracy by means of a radar for a vehicle.

[0009] According to the present invention, a radar antenna arrangement for a vehicle including at least one vehicle component is provided. The radar antenna arrangement has a plurality of radar mechanisms, which are designed to send and / or receive radar beams. The radar mechanisms are arranged on the component surface of the vehicle component. It is characterized in that the radar antenna arrangement has at least one antenna row for determining the azimuth of the radar beam, and the at least one antenna row has a plurality of radar mechanisms. A plurality of radar mechanisms are arranged along the antenna row, wherein directly adjacent radar mechanisms have corresponding horizontal distances from each other. The radar antenna arrangement also has at least one antenna column for determining the elevation angle of the radar beam. A plurality of radar mechanisms are arranged along the antenna column, wherein directly adjacent radar mechanisms have corresponding vertical distances from each other. At least one antenna row and at least one antenna column enclose an angle from 5 degrees to 180 degrees.

[0010] In other words, a radar antenna arrangement is provided, which is set for at least one vehicle component. The radar antenna arrangement relates to a cluster antenna, which forms a so-called array in a plane located in the component surface of the vehicle component through at least one antenna row and at least one antenna column. At least one antenna column forms an internal angle α from 5 degrees to 180 degrees with at least one antenna row. A plurality of radar mechanisms are arranged in the component surface. The radar mechanism is arranged to receive and / or transmit radar beams. A plurality of radar mechanisms are arranged in at least one antenna column and at least one antenna row, wherein directly adjacent radar mechanisms have corresponding distances from each other. The vertical distance and the horizontal distance can be the same or different. The distance can be, for example, an integer multiple of a predetermined half radar wavelength. It can be provided that the antenna mechanism arranged in the antenna column is arranged to collect the elevation angle of the received radar beam or define the elevation angle of the radar beam to be transmitted. The antenna row can be designed to collect the azimuth angle of the radar beam or define the radar beam to be transmitted. The advantage generated by the present invention is that the component surface of the vehicle component can be used as the surface of the radar antenna arrangement. In particular, it can be provided that a larger vehicle component, such as a door or a window, is used to provide the component surface. As a result, the surface of an existing vehicle component can be used for the radar device without having to arrange additional components on the vehicle to provide the surface.

[0011] The invention includes other optional refinements, through which further advantages result.

[0012] The improved solution of the present invention provides that at least one antenna row and at least one antenna column enclose an angle of from 60 degrees to 120 degrees. In other words, at least one antenna column and at least one antenna row enclose an angle of from 60 degrees to 120 degrees. For example, it can be provided that at least one antenna row and at least one antenna column enclose an angle of 90 degrees.

[0013] The improvement of the present invention provides that the corresponding horizontal distance and the corresponding vertical distance of the radar devices are integer multiples of a predetermined radar wavelength, wherein the radar wavelength is between 0.011m and 0.014m or 0.0037 and 0.0038m. In other words, the distance between directly adjacent radar devices in the antenna column and / or antenna row is a multiple of half the wavelength of the radar wavelength. The wavelength is equal to the wavelength used in the spectrum of 24.05GHz to 24.25GHz, or 21.65GHz to 26.65GHz, or 77GHz to 81GHz. The following advantages are produced: It is possible to achieve a constructive superposition of the signals of the corresponding received partial beams of the radar beam.

[0014] The improvement of the present invention provides that the radar device is arranged in a sparse array arrangement. In other words, it is an incompletely occupied cluster antenna in which the corresponding vertical distance and the corresponding horizontal distance are not the same. Therefore, along at least one radar row and / or at least one radar column, each position will not be occupied by the radar device. The resulting advantage is that the number of radar devices is reduced, and thus the amount of measurement data to be evaluated is reduced. By simulating the far field (fernfeld) of the radar beam for the corresponding radar antenna arrangement, it is possible to save radar devices without a significant loss of resolution. The sparse array arrangement is an under-occupied (unterbesetzt), in other words, an incompletely occupied antenna arrangement, and the individual distances of its radar devices are greater than λ / 2. In other words, the individual positions at a distance of λ / 2 from the directly adjacent radar device are not occupied, that is, there is no radar device at these positions.

[0015] The improved scheme of the present invention provides that the radar antenna arrangement has at least one optical conductor, wherein the radar device is connected to the control unit of the radar antenna arrangement via at least one optical conductor. The optical conductor is designed to transmit optical signals between the control unit and the radar device. In other words, it is provided that the radar device is controlled by the control unit, wherein the transmission of the partial beam by the corresponding radar device is controlled by the control unit by means of the optical signal. In order to transmit the optical signal, the control unit is connected to the radar device via at least one optical conductor. If a partial beam of the radar beam is received by one of the radar devices, the partial beam is converted by the radar device into an optical signal and transmitted to the control unit via the optical conductor. The control unit can process the optical signal in order to reconstruct the received radar beam from the partial beam. The resulting advantage is that the corresponding partial beam of the radar beam does not need to be processed in the corresponding radar device, and therefore the time stamp does not need to be provided by the radar device. Therefore, the measurement data can be centrally evaluated in the control unit. Therefore, it is not necessary to synchronize the individual radar devices.

[0016] A refinement of the invention provides that the vehicle component is a window pane of the vehicle. In other words, the radar antenna arrangement includes the window pane as a vehicle component. The resulting advantage is that the radar antenna arrangement has a vehicle component with a relatively large surface area. For example, it can be provided that the individual radar devices are arranged on the window pane of the vehicle. The radar devices can be arranged, for example, on the side of the window pane facing the vehicle interior and can be located, for example, in the black printed area. The radar devices can be connected to each other via optical conductors, which can be arranged on the window pane.

[0017] A refinement of the invention provides that the radar device is arranged in the vehicle window. In other words, it is provided that the radar device is arranged in the vehicle window so that it is at least partially surrounded by the vehicle window. For example, it can be provided that the vehicle window is a multi-layer glass composed of multiple layers. The radar device can be arranged between adjacent layers of the vehicle window. The resulting advantage is that the radar device is fixed in certain positions that are only slightly affected by thermal fluctuations.

[0018] A refinement of the invention provides that at least one optical waveguide is at least partially arranged in the window pane. In other words, at least a subset of the at least one optical waveguide is surrounded by the window pane. For example, it can be provided that a glass fiber serving as an optical waveguide is arranged between two layers of the window pane. It can also be provided that a recess in the window pane is filled with an optical waveguide in order to connect the radar device to or in the window pane.

[0019] The improvement of the present invention provides that the vehicle component is an A-pillar, a B-pillar and / or a C-pillar for the vehicle. In other words, the radar device has an A-pillar, a B-pillar or a C-pillar. The advantage resulting from this is that the radar device can be arranged in an area that is not visible to the driver.

[0020] A refinement of the invention provides that the vehicle component is a part of the vehicle body. In other words, it is provided that the radar antenna arrangement has a component of the vehicle body. For example, it can be provided that the radar device is arranged on or in the front fender, mudguard or bumper of the vehicle. The resulting advantage is that vehicle surfaces pointing in different directions can be used. Thus, 360-degree angular coverage can be achieved by a variety of radar antenna arrangements of the vehicle.

[0021] A refinement of the invention provides that the main radiation direction of at least one radar device is oriented at the Brewster angle relative to the outer surface of the vehicle window. In other words, at least one radar device is oriented such that the partial beam emitted by the radar device strikes the interface between the vehicle window and the air at the Brewster angle in the main radiation direction of the radar device. This has the advantage that a polarized radar beam is emitted from the vehicle window and a portion of the radar radiation input into the vehicle window is minimized.

[0022] The present invention also includes a method for calibrating a radar antenna arrangement. In the method, it is provided that a control unit controls a first radar device by means of an optical signal to emit a predetermined partial beam. A predetermined partial beam is emitted by the first radar device. At least a portion of the partial beam is reflected in the window glass, so that it is further propagated in the window glass. The portion of the partial beam reflected in the window glass is received by a second radar device in the radar device. The second radar device in the radar device transmits an optical signal to the control unit. The distance between the first radar device and the second radar device in the radar device is determined by the control unit. In other words, the relative position of the first radar device and the second radar device in the radar device is determined by the control device. This occurs in that the control unit causes the output of a predetermined calibration of the aperture by means of an optical signal through the first control unit. The partial beam is sent into the window glass by the first radar device. A portion of the partial beam is emitted from the window glass on the outer surface of the window glass. The remaining portion of the partial beam can be reflected back into the window glass on the outer surface. Due to multiple reflections, a portion of the partial beam can propagate in the window glass. The reflected partial beams can impinge on a second radar device in the radar device and be collected by it. The second radar device in the radar device then sends a light signal to the control unit. The control unit can now determine the distance between the two radar devices, for example based on the phase of the received partial beams. It can be provided that, for example, a plurality of radar devices are controlled by the control unit for emitting corresponding partial beams. By evaluating the light signals emitted by the corresponding radar devices, the geometrical relationship between the individual radar devices in the radar antenna arrangement can be determined by the control unit.

[0023] The invention also encompasses a vehicle having at least one radar antenna arrangement. The vehicle can be, for example, a truck or a passenger car. It can be provided that the vehicle can have, for example, a plurality of radar antenna arrangements, wherein a 360-degree area in a plane around the vehicle can be covered.

[0024] The present invention also covers developments of the vehicle according to the invention and of the method according to the invention which have the features already described in conjunction with the development of the radar antenna arrangement according to the invention. For this reason, corresponding developments of the vehicle according to the invention and of the method according to the invention will not be described here. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention also includes combinations of features of the described embodiments.

[0026] The following describes an embodiment of the present invention. It is shown that:

[0027] Figure 1 : Radar antenna layout;

[0028] Figure 2: Possible arrangement of radar mechanisms in antenna rows or antenna columns of a radar antenna arrangement;

[0029] Figure 3 : Possible implementations of radar antenna arrangements;

[0030] Figure 4 : Possible implementations of a vehicle with a radar antenna arrangement; and

[0031] Figure 5 : A possible flow of a method for calibrating a radar antenna arrangement. DETAILED DESCRIPTION

[0032] The embodiment explained below is a preferred embodiment of the present invention. In this embodiment, the described components of the embodiment are respectively features of the present invention that are observed independently of each other, and these features also improve the present invention independently of each other, and are therefore also considered as components of the present invention individually or in a combination different from that shown. In addition, the described embodiment can also be supplemented by other features of the present invention that have already been described.

[0033] In the figures, elements with the same function are respectively provided with the same reference symbols.

[0034] Description of the drawings: Figure 1A radar antenna arrangement 1 is shown. The radar antenna arrangement 1 can be provided for a vehicle 2 and has at least one vehicle component 3. The radar antenna arrangement 1 can have a plurality of radar devices 4, which can be arranged on a component surface 5 of the component 3. The radar devices 4 can be arranged in at least one antenna row 6 and at least one antenna column 7. Directly adjacent radar devices 4 can each have a corresponding horizontal distance 8 from one another in at least one antenna row 6, and adjacent radar devices 4 can have a corresponding vertical distance 9 from one another in an antenna column 7. At least one antenna row 6 can be provided for determining an azimuth angle 10 of a radar beam 12. At least one antenna column 7 can be provided for determining an elevation angle 11 of a radar beam 12. The individual radar devices 4 can be connected to a control unit 15 via an optical conductor 13 for transmitting a light signal 14. The individual radar devices 4 can be designed to generate a light signal 14 when receiving a partial beam 12a of the radar beam 12 and transmit it to the control unit 15 for evaluation. The control unit 15 can have, for example, a microprocessor or a microcontroller and is designed to receive and evaluate the individual light signals 14. It can be provided that the control unit 15 determines the azimuth 10 and the elevation 11 of the received radar beam 12 by means of the fusion of the light signals 14. It can be provided that the elevation 11 of the radar beam 12 is determined by evaluating the light signals of the radar devices 4 arranged in the antenna column 7, and the azimuth 10 is determined by evaluating the light signals 14 of the radar devices 4 in the antenna row 6. For example, the origin can be determined by the phase difference between the partial beams 12a of the radar beam respectively received at the respective radar devices 4. The evaluation in the control unit 15 has the advantage that no evaluation needs to be carried out in the individual radar devices 4. As a result, synchronization between the individual radar devices 4, which is usually required in order to provide synchronized time stamps in the evaluated signals, is omitted.

[0035] Figure 2A possible arrangement of radar devices in antenna rows or antenna columns of a radar antenna arrangement is shown. The radar antenna arrangement 1 can have a plurality of radar devices 4, which can be arranged, for example, on the side of a vehicle window facing the vehicle interior. These radar devices 4 can each include a radar antenna 16 and a radar chip 17 for providing and / or receiving a radar beam 12 to be transmitted. These radar devices 4 can be arranged at predetermined positions along the antenna row 6 or antenna column 7 so that they have corresponding distances 8, 9 from each other, which are integer multiples of half the wavelength λ. It can be provided that the individual radar devices 4 are arranged along the antenna row 6 and / or antenna column 7 in a so-called sparse array arrangement. This means that the individual positions are not occupied, so it is not a fully occupied array of the radar antenna arrangement 1. This results in the advantage of reducing the number of radar devices 4. By means of the predetermined arrangement, it can be achieved that a predetermined resolution can be provided, and the number of radar devices 4 can be reduced. By superimposing the individual beams 12a transmitted by the individual radar devices 4, the radar beam 12 can be provided as a synthetic radar beam. It is therefore a cluster antenna. The radar device 4 may have a respective radar chip 17 and a respective radar antenna 16. The radar device 4 may be arranged directly on the vehicle window glass. The respective individual beams 12a transmitted by the radar device 4 penetrate the material of the vehicle component 3 and form a lobe characterizing the cluster antenna by interference with the radar beam 12 in the far field of the radar antenna arrangement 1. By determining the phase position of the respective individual beam 12a by the control unit 15, for example, the elevation angle 11 of the radar beam 12 may be determined. It may be provided that one or more radar devices 4 are oriented in such a way that they transmit their respective individual beams 12a onto the boundary surface of the vehicle window so that the angle of incidence θ1 coincides with the Brewster angle β. In this case, a portion of the individual beams is output in polarized form at an exit angle θ2. The remaining portion may be coupled into the vehicle window at a reflection angle θ3.

[0036] The distances 8, 9 between adjacent radar devices 4 can be different from one another. For example, it can be provided that not every distance 8, 9 is half a wavelength, but rather an integer multiple of half a wavelength λ.

[0037] Figure 3A possible embodiment of a radar antenna arrangement 1 is shown. It can be provided that the radar device 4 can be arranged in the vehicle component 3. The radar device 4 can be arranged in the antenna row 6 in order to be able to define or collect the determination of the azimuth angle 10 of the radar beam 12. By the predetermined control of the respective radar device 4 by the control unit 15 via the light signal 14, it can be provided that a synthetic radar beam 12 with a predetermined azimuth angle 10 is generated by interference. When the radar beam is received, the light signal 14 can be transmitted to the control unit 15 by the respective radar device 4. The control unit 15 can calculate the azimuth angle 10 of the radar beam 12 based on the phase position of the light signal 14. For example, it can be provided that the vehicle window is a multi-layer glass, wherein the radar device 4 and a section of at least one optical conductor 13 can be arranged in the vehicle window. They can thus be arranged, for example, between two layers of the vehicle window. The resulting advantage is that the individual radar devices 4 are fixed in their position. The individual radar devices 4 can be connected to the control unit 15 via at least one optical conductor 13. This arrangement has the advantage that the radar device 4 is arranged in a protected position.

[0038] Figure 4 A possible embodiment of a vehicle with a radar antenna arrangement is shown. It can be provided that the radar antenna arrangement 1 can be arranged on different components 5 of the vehicle 2. For example, it can be provided that the radar antenna arrangement 1 can be arranged on or in the front window of the vehicle, the rear window and the side windows of the vehicle. It can also be provided that a radar antenna arrangement 1 is arranged, for example, in a door, a shock absorber or an ABC column. By using a plurality of radar antenna arrangements 1 on different vehicle components 5 of the vehicle 2, the advantage is that 360-degree coverage can be achieved by the radar antenna arrangement 1.

[0039] Thus, the figure shows a vehicle 2 with a plurality of radar antenna arrangements 1 on different vehicle components 5. The radar antenna arrangement 1 can have a plurality of radar devices 4 and together form a radar antenna arrangement 1 that can collect a 360-degree angle range around the vehicle 2. For this purpose, it can be provided that the radar device 4 is arranged on a window pane of the vehicle 2, such as a front window, a rear window and / or a side window. The radar device 4 can also be arranged on a body component, such as a shock absorber or a fender. The arrangement on the A-pillar, B-pillar, and C-pillar can be realized, and it can be arranged on the vehicle without restricting the driver's line of sight. The arrangement on the front window can be designed in such a way that at least one antenna column 7 and at least one antenna row 6 have an angle of, for example, 60 to 120 degrees with respect to each other and span the plane of the cluster antenna. It can also be provided that an antenna row 6 or an antenna column 7 is assigned to each edge of the front window, so that the area of ​​the front window is bounded by the radar device 4. If the distance to an object reflecting the radar beam 12 is measured, a three-dimensional collection of the environment can be achieved.

[0040] Figure 5The sequence of a method for calibrating a radar antenna arrangement is shown. It may be provided that the radar device 4 of the radar antenna arrangement 1 may be arranged in a vehicle window as a vehicle component 5. In order to be able to determine the exact distance 8, 9 between adjacent radar devices 4, it may be provided that the described method is carried out.

[0041] In a first step S1 of the method, control unit 15 transmits optical signal 14 to first radar device 4 via at least one optical fiber in order to transmit partial beam 12 a via first radar device 4 .

[0042] In step S2 , first radar device 4 can receive light signal 14 and transmit partial beam 12 a into the vehicle window.

[0043] In step S3, the partial beam 12a is incident on the interface between the vehicle window glass and the air and is partially reflected, so that a portion of the partial beam 12a is reflected back into the vehicle window glass. The reflected partial beam 12a may be incident on another interface between the glass and the air and may be partially reflected back into the vehicle window glass again. Thus, the partial beam 12a may propagate in the vehicle window glass.

[0044] In step S4 , the partial beam 12 a can be collected by a second radar device in the radar device 4 . The second radar device in the radar device 4 can then send an optical signal 14 to a control unit 15 via at least one optical conductor 13 .

[0045] In step S5, the control unit 15 receives the light signal 14 and determines the distance 8, 9 between the first radar device and the second radar device in the radar device 4, for example based on the time interval between sending the light signal 14 to send the partial beam 12a and receiving the light signal of the second radar device 4, or through the phase difference.

[0046] For automated driving, the most reliable possible perception of the surroundings is crucial. Here, the surroundings are collected with the help of sensors such as radar, lidar and cameras. A 360-degree 3D collection of the environment is particularly important, so that all static and dynamic objects are collected. Lidar in particular plays a key role in redundant, robust environmental collection, because this sensor type can measure distances precisely in environmental collection and can also be used for classification. However, these sensors are costly and their structure is complex. In particular, 360-degree 3D environmental collection is problematic, because either many smaller individual sensors are required to ensure this, which usually work with many individual light sources and detector elements, or large sensors are installed. However, even for smaller sensor types, their spatial dimensions are still in the range of 10 cm × 10 cm × 10 cm, and invisible installation positions are not yet allowed. In addition, the measurement data collected individually from each sensor must be processed and / or fused individually. Here, accurate time stamps are particularly important for real-time processing, which makes data acquisition and classification more complicated. In the field of passive safety systems, as well as in the field of level 4 and level 5 automated driving, the ability to differentiate between traffic participants is particularly important for protecting both occupants and traffic participants. For this, reliable perception of the surroundings is essential. To ensure this, the surroundings must be perceived in all three spatial dimensions with the highest possible resolution. Modern cameras and LIDAR systems are able to ensure this perception of the surroundings, but in conditions of low visibility such as fog, snow or darkness, their quality is impaired or they fail completely. Radar sensors, on the other hand, are not subject to these limitations, but must be arranged in an array with a large number of different sensors for 3D imaging with high resolution. In addition, they must be synchronized in terms of transmission and reception times, which is extremely challenging from a technical point of view. It is therefore advantageous if the individual radar sensors are as small, simple, flexible, fault-tolerant, robust and inexpensive as possible. For this purpose, as little electronics as possible must be installed on the radar sensor itself, and the digital data processing must be decentralized in a central control unit. In conventional radar systems produced in series, there is an angular separability in azimuth of 10 to 4 degrees. The angular separability in elevation is usually even smaller, so much so that imaging methods cannot be used for radar data. The angular separability of current LiDAR systems is in the range of 0.1 degrees, which is not achievable with current radar systems.

[0047] The dimensions of current radar sensors installed in cars are typically 10×10 cm. The maximum angular resolution achieved with this is approximately 2 degrees and only allows 2D-surroundings perception. Current radar sensors are too spatially dimensional for the vehicle with a small aperture, resulting in a too low resolution. This does not allow adequate perception of the environment for autonomous driving. The installation of multiple sensors requires their time synchronization, which is technically challenging and costly. Nano radars have dimensions in the range of 5×5 cm and can be integrated into vehicles more easily due to their compact construction. Nano radars have the same disadvantages. In addition, the range of nano radars is currently limited to approximately 45 m, which is too low, especially for urban scenarios. Using the synthetic aperture method (English: "Synthetic Aperture Radar" SAR), the resolution can be increased to the centimeter range. The SAR method can only be used perpendicular to the direction of travel. It is not possible to make predictions in the direction of travel or in the opposite direction with this method. In addition, the data processing required after the measurement is very computationally intensive.

[0048] Installing many electronic components in the sensors increases their spatial size and their costs, making the use of multiple sensors impossible. In addition, the time synchronization of the sensors is technically challenging. But if the aperture is realized by distributed antennas and then decentralized digital data processing in a central control unit, the electrical transmission of the transmit and receive signals is problematic because the losses would amount to several dB.

[0049] Furthermore, multiple individual sensors need to be used. The large spatial dimensions of the sensors do not allow for concealed installation on the vehicle, so they remain visible. Due to the use of multiple individual sensors, considerable effort is required to synchronize the individual sensors. Data fusion is also time-consuming and error-prone, since there is no central data acquisition, but rather each individual sensor collects and forwards the measurement data itself. This leads to high costs.

[0050] The radar antenna arrangement uses a photonic integrated radar chip as the radar mechanism to span a large radar array.

[0051] These radar mechanisms are at least partially connected to the control unit via at least one optical conductor. The control unit has a central optical transmitting unit, which is designed to provide an optical radar drive signal and input it into at least one optical conductor. The radar mechanism has a corresponding optical receiving unit and a radar transmitter, wherein the optical receiving unit is designed to receive the optical radar drive signal via at least one optical conductor, convert it into an electrical radar drive signal, and provide it to drive the radar transmitter. The radar mechanism has a radar receiver, a mixer and an optical modulation unit, wherein the mixer is designed to mix the radar echo signal received by the radar receiver with the electrical radar drive signal, and wherein the modulation unit is designed to modulate the mixed signal onto the optical radar drive signal and input it into at least one optical conductor. The central unit also includes a central optical receiving unit and an evaluation unit, wherein the evaluation unit is designed to evaluate the modulated signal received by the central optical receiving unit and output radar information derived therefrom.

[0052] The basic idea of ​​the present invention is to realize the signal transmission between the central unit and the radar transmitting unit or the radar receiving unit optically. For this purpose, the radar drive signal is optically generated in the central unit and transmitted to at least one radar receiving unit and / or at least one radar transmitting unit via at least one glass fiber. In the radar transmitting unit, the optical radar drive signal is then converted into an electrical radar drive signal and used to drive the radar transmitter. The radar echo signal received by the radar receiver is mixed with the electrical radar drive signal in the mixer of the radar receiving unit. Then the mixed signal is modulated onto the optical drive signal by means of a modulation unit, input into the glass fiber, and transmitted back to the central unit. The modulated optical signal is received in the central unit and evaluated by means of an evaluation unit. The result is then provided as radar information. The advantage of the present invention is that optical and electrical devices are cointegrated for generating and receiving radar echo signals. The generation of the radar drive signal is optically performed centrally in the central unit, and the transmission to the radar transmitting unit or the radar receiving unit is also performed optically. Here, in contrast to electrical transmission, when transmitting via glass fiber, a signal attenuation several orders of magnitude lower can be used. Lower attenuation can be achieved for a large number of radar transmitting units and radar receiving units to jointly provide radar drive signals. In addition, glass fibers have a significantly lower weight than corresponding cables and are less sensitive to external interference, such as electromagnetic fields.

[0053] Another advantage of centrally optically generating the radar drive signal is that the radar transmitting unit and the radar receiving unit can be manufactured and provided in a compact design with small dimensions. This saves installation space and costs. In the solution according to the invention, the complexity of the radar system lies in the central unit and no longer in the individual radar transmitting units or individual radar receiving units. The individual radar transmitting units and radar receiving units can thus be manufactured simply and cost-effectively and, in the event of a fault, can be easily and quickly replaced.

[0054] The radar antenna arrangement enables the individual radar chips to be concealedly mounted behind or inside the front window, A, B, C pillars, fenders, bumpers or similar structures. Mounting in the windshield is advantageous because the windshield has the necessary rigidity and therefore the individual antenna elements are less subject to positional changes relative to each other due to vibrations, etc., compared to the bumper.

[0055] The radar chip with antenna can be attached directly to the inside of the windshield (cockpit) or can be integrated directly into the window material. In both cases, the beam is radiated outwards. Due to the large-area arrangement of the radar chip, a large aperture can be formed, so that angular resolutions of 0.1 degrees and below can be achieved. Image processing algorithms can therefore be used for the radar data.

[0056] Reflections from the Tx radar chip at the window-air transition can be minimized by orienting the radar antenna to radiate at the Brewster angle. The same applies to the Rx channel. At the same time, the p-polarization component of the radar radiation can be suppressed. The residual radiation input into the window can be used to calibrate the individual chips, for example by determining the relative position of the chips to each other. The antennas of the array do not necessarily have to be arranged at distances of integer multiples of half a wavelength (fully occupied array), but can also contain gaps when the antenna positions are cleverly selected. This sparse array concept makes it possible to achieve only slight changes in the beam characteristics, so that a high angular separability down to 0.1 degrees can always be clearly achieved. For optical contact of the radar chip with the optical carrier signal, a waveguide can be integrated directly into the window.

[0057] Installing individual radar chips, which form a large overall aperture, can achieve a resolution comparable to that of LiDAR. By means of a sparse array configuration, a reduction in the amount of data to be processed can be achieved without significantly limiting the resolution. Due to the small size of the radar mechanism, the radar mechanism can be arranged in a concealed position, so that these radar mechanisms are not visible from the outside or the inside. It can be integrated in or behind the vehicle window, and black printing can also be used. It can be integrated in the ABC-pillar or the front panel. The following possibilities are created: image processing algorithms are applied directly to the radar data in the control unit. By arranging the radar mechanism in a large number of different components of the vehicle, a large field of view can be covered with a high resolution comparable to that of LiDAR. In the vehicle window glass, there is also the possibility of integrating optical waveguides directly into the vehicle window glass for connecting the radar mechanism to the control unit. When the radar mechanism is arranged in the vehicle window glass, the residual radiation input into the vehicle window glass can be used to calibrate the individual chips.

[0058] The radar antenna arrangement described is inexpensive compared to known methods, since mature and established technologies are used in production, which are available in large-scale production. In addition, it has a relatively simple structure. The sparse array arrangement allows the number of individual sensors to be reduced. The use of the part of the radar beam that is coupled into the vehicle window pane allows a simple calibration of the radar antenna arrangement 1. Optical coupling allows a simple synchronization of the individual antenna elements. It creates the possibility of applying image processing algorithms directly to the radar data.

[0059] All radar applications, e.g. also for protecting production robots.

[0060] Overall, this example shows how the present invention provides the possibility of arranging a radar system on a vehicle.

[0061] List of Reference Numerals

[0062] 1 Radar antenna layout

[0063] 2 Vehicles

[0064] 3 Vehicle components

[0065] 4 Radar mechanism

[0066] 5 Component surface

[0067] 6 Antenna Row

[0068] 7 Antenna Column

[0069] 8 Horizontal distance

[0070] 9 Vertical distance

[0071] 10 Azimuth

[0072] 11 Elevation

[0073] 12 Radar Beam

[0074] 12a Single beam

[0075] 13 Photoconductor

[0076] 14 light signal

[0077] 15 Control Unit

[0078] 16 Radar Antenna

[0079] 17 Radar Chip

[0080] S1-S5 Calibration Steps

[0081] α Angle between antenna rows and antenna columns

[0082] λ Wavelength

[0083] β Brewster angle

[0084] θ1 Angle of incidence

[0085] θ2 Angle of emission

[0086] θ3 Reflection angle.

Claims

1. A radar antenna arrangement (1) for a vehicle (2) comprising at least one vehicle component (3), wherein: The radar antenna arrangement (1) - having a plurality of radar devices (4) which are designed to transmit and / or receive radar beams (12), - the radar device (4) is arranged on a component surface (5) of the vehicle component (3), The radar antenna arrangement (1) - having at least one antenna row (6) for determining the azimuth angle (10) of the radar beam (12), the at least one antenna row (6) comprising a plurality of the radar devices (4), wherein the radar devices (4) are arranged along the at least one antenna row (6) and directly adjacent radar devices (4) have a corresponding horizontal distance (8) from one another, - having at least one antenna row (7) for determining the elevation angle (11) of the radar beam (12), the at least one antenna row (7) comprising a plurality of the radar devices (4), wherein the radar devices (4) are arranged along the antenna row (7) and directly adjacent radar devices (4) have a corresponding vertical distance (9) from one another, wherein the at least one antenna row (6) and the at least one antenna row (7) enclose an angle α of from 5 degrees to 180 degrees, - having at least one optical waveguide (13), wherein the radar device (4) is connected to a control unit (15) of the radar antenna arrangement (1) via the at least one optical waveguide (13), The optical fiber (13) is designed to transmit an optical signal (14) between the control unit (15) and the radar device (4). The vehicle component (3) is a vehicle window glass, and The at least one optical waveguide (13) is arranged at least partially in the vehicle window.

2. The radar antenna arrangement (1) according to claim 1, characterized in that The at least one antenna row (6) and the at least one antenna column (7) enclose an angle α ranging from 60 degrees to 120 degrees.

3. The radar antenna arrangement (1) according to claim 1, characterized in that The corresponding horizontal distance (8) and the corresponding vertical distance (9) of the radar device (4) are integer multiples of a predetermined radar wavelength λ, wherein the radar wavelength λ is between 0.011 m and 0.014 m or between 0.0037 and 0.0038 m.

4. The radar antenna arrangement (1) according to any one of the preceding claims 1 to 3, characterized in that The radar mechanisms (4) are arranged in a sparse array arrangement.

5. The radar antenna arrangement (1) according to claim 1, It is characterized in that The radar device (4) is arranged in the vehicle window.

6. The radar antenna arrangement (1) according to any one of claims 1 to 5, It is characterized in that The main radiation direction of at least one of the radar devices (4) is oriented at a Brewster angle β relative to the outer surface of the vehicle window.

7. Method for calibrating a radar antenna arrangement (1) according to any one of claims 1 to 6, characterized in that - a control unit (15) controls a first radar device in the radar device (4) by means of a light signal (14) to emit a predetermined partial beam, the predetermined partial beam is emitted by the first of the radar devices (4), wherein the light signal (14) is transmitted by means of an optical fiber (13), - causing at least a portion of the partial beam to be reflected in the vehicle window and received by a second radar device in the radar device (4), - transmitting a light signal (14) from the second radar device in the radar device (4) to the control unit (15) by means of the optical waveguide (13), The control unit (15) determines a distance between a first radar device and a second radar device in the radar device (4).

8. A vehicle (2) having at least one radar antenna arrangement (1) according to any one of claims 1 to 6.

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