Method for determining angular information by means of a radar device for a motor vehicle

Abstract

The invention relates to: a method for determining angular information (14) by means of a radar device (2) for a motor vehicle (1); and the radar device (2). For the determination, in particular only a single antenna (3) of the radar device (2) is used to emit radio waves and / or receive echoes. The method comprises: determining (S1) whether at least one object (8) is located within a detection range (9) of the radar device (2) by evaluating the received echoes; and, if the at least one object (8) is determined to be located within the detection range, determining (S3) the angular information (14) which describes the angle at which the at least one object (8) is located relative to the radar device (2) by evaluating a temporal variation of the received echoes and by evaluating the received echoes that were generated at the at least one object (8) by reflections of radio waves that were transmitted at a plurality of different frequencies.

Description

[0001] Method for determining angle information using a radar device for a motor vehicle

[0002] The invention relates to a method for determining angle information using a radar device for a motor vehicle. For the determination, radio waves are preferably emitted and / or echoes are received using an antenna of the radar device. The invention also relates to a radar device, a control device for such a radar device, a motor vehicle with such a radar device, and a computer program product for implementing the method.

[0003] A motor vehicle can have at least one radar device designed to detect at least one object within a detection range of the radar device. The radar device is also designed to determine a distance to the object. The radar device for the motor vehicle is arranged, for example, in a front area, a rear area and / or a side area of ​​the motor vehicle. The detection range of the radar device is then at least a partial area of ​​the surroundings of the motor vehicle. Alternatively or additionally, the radar device can be arranged in an interior of the motor vehicle, in which case the detection range comprises at least part of an interior of the motor vehicle.

[0004] The radar device typically has several individual antennas, each of which can be configured as a transmitting antenna and / or a receiving antenna. The respective antenna can transmit radio waves and / or receive echoes, with the echoes being generated by reflections of the transmitted radio waves from at least one object in the detection range.

[0005] In order to save costs and / or the required installation space, for example, the motor vehicle can have a radar device with only a single transmitting antenna and / or receiving antenna. However, with such a radar device, the position of the object relative to the radar device, for example in the form of angular information that describes the angle at which the at least one object is arranged to the radar device, cannot be reliably determined. This is because radar devices with multiple antennas are typically used for reliable position determination. It is therefore sensible to adapt the radar device so that it can determine the angular information using a single antenna. EP 0 477 155 A2 shows a device for angular resolution and measurement of radar targets using a radar device that repeatedly transmits a signal at at least two frequencies.

[0006] US Pat. No. 8,035,548 B2 describes an evaluation method that performs object detection based on a radar sensor. The radar sensor synchronously emits at least two different radar beams that cover an angular range to be scanned.

[0007] It is the object of the invention to provide a solution by means of which angular information about an object can be reliably determined using a radar device.

[0008] The problem is solved by the subject matter of the independent patent claims.

[0009] A first aspect of the invention relates to a method for determining angular information using a radar device for a motor vehicle. The radar device that carries out the method is preferably mounted in a motor vehicle, i.e., arranged therein. The angular information describes the angle at which at least one object that is detected by the radar device is arranged relative to the radar device. The at least one object is located within a detection range of the radar device. The angular information thus comprises a position specification of the object. Based on the angular information and together with distance information, which can also be determined by the radar device, the object can be located within the detection range of the radar device and thus in an environment of the radar device.The angle information can alternatively be understood as position information that describes a position of the object in the detection range of the radar device, in particular by means of an angle.

[0010] To determine the angle information, radio waves are emitted and / or echoes are received, in particular, using only a single antenna of the radar device. The echoes are created when the radio wave is reflected by the at least one object in the detection range of the radar device. The single antenna is preferably both a transmitting antenna and a receiving antenna, i.e., it can emit the radio waves and also receive the echoes. Alternatively, the radar device can have a single transmitting antenna for emitting the radio waves and a single receiving antenna for receiving the echoes, wherein the transmitting antenna and the receiving antenna are spatially separated from one another. The radar device can comprise multiple antennas, for example, multiple transmitting antennas and / or receiving antennas.However, the method according to the invention is preferably carried out using only the single respective antenna, i.e., either using the single transmitting and receiving antenna or using the single transmitting antenna and the single receiving antenna. Alternatively or additionally, the method can be carried out using multiple antennas, for example, using multiple transmitting antennas and / or receiving antennas.

[0011] The method comprises determining whether at least one object is located within the detection range of the radar device. The determination is carried out by evaluating the received echoes. For example, an energy spectrum can be determined and evaluated by evaluating the echoes, looking for extreme values ​​within it, wherein the respective extreme value can at least indicate that the object is located within the detection range. To determine whether the at least one object is located within the detection range, the radar device emits at least one radio wave, preferably a plurality of radio waves, and receives at least one echo, preferably a plurality of echoes. The emitted radio wave, preferably the plurality of emitted radio waves, can also be taken into account during the determination.

[0012] If at least one object is detected, the angle information is determined. The angle information is determined by evaluating a temporal change in the received echoes, on the one hand, and by evaluating the received echoes generated by reflections of radio waves emitted at different frequencies from the at least one object, on the other. To determine the angle information, two different evaluation steps are performed based on the received echoes. Firstly, consecutively received echoes are taken into account; this means that radio waves are emitted one after the other and the corresponding echoes are received in order to be able to compare the sequentially recorded echoes with each other.This is useful, for example, in order to be able to detect and evaluate a change in the location of a moving radar device and / or a moving object relative to the radar device, which makes it possible to localize the object relative to the radar device. If, for example, the motor vehicle with the radar device drives past a parking space that is bordered on at least one side by an object, such as a parked vehicle, radio waves are emitted from various positions on the motor vehicle and echoes are received that describe the parked vehicle and thus the object from different perspectives. The changes in the individual received echoes are then evaluated, for example with regard to the shape of the respective received echo, which can provide information that at least helps to determine the angular information.

[0013] Secondly, received echoes are evaluated where the underlying radio waves have different frequencies. For example, radio waves that differ from one another in terms of their frequency can be transmitted one after the other using a single antenna. This procedure is based at least on the knowledge that the aperture angle of the radar device, in particular a so-called -3dB value of the radar device, is inversely proportional to the frequency at which the radio wave is transmitted. The higher the frequency of the transmitted radio wave, the smaller the -3dB value, for example. By comparing, for example, the shape of the received echoes that were received when radio waves were transmitted at at least two different frequencies, the angular information of the object can be determined.

[0014] According to the invention, two different evaluations are performed: firstly, the evaluation of the temporal change in the received echoes, and secondly, the evaluation of the received echoes generated by the reflection of radio waves of different frequencies in order to reliably determine the angular information. Thus, with a radar device with only a single antenna for transmitting and / or receiving echoes, it is possible to reliably determine the position or localize the detected object within the radar device's detection range by determining the angular information. Using this method, the angular information for an object can therefore always be reliably determined using a radar device.

[0015] The method according to the invention is preferably carried out by means of a control device of the radar device. The control device can be a component of the radar device, which is arranged, for example, in a housing of the radar device. Alternatively or additionally, it can be designed as a separate component, spatially separated from the single respective antenna of the radar device. The control device can receive measurement data and / or other information from the single respective antenna. It is assumed that the control device has information about both the transmitted radio waves and information about the received echoes. The control device can, for example, specify the radio waves to be transmitted and / or evaluate the received echoes. The method can therefore be understood as a computer-implemented method.

[0016] At least for evaluating the temporal change, all received echoes can be stored for a time window greater than zero, for example, in a memory unit of the control device and / or the radar device. The time window can depend on the current speed of the motor vehicle in which the radar device is installed. The method improves the angular resolution of the radar device. The method determines the exact position of the object in the detection range.

[0017] One embodiment provides that when evaluating the temporal change, the direction in which the radar device and / or the at least one object are moving relative to one another is determined. The direction determined in this way is taken into account when determining the angular information, i.e., it is incorporated into the determination of the angular information. The information regarding the direction in which the radar device and object are moving relative to one another can be determined directly by evaluating the temporal change and can contribute to determining the angular information particularly precisely. This information can be referred to as directional information, which describes the direction in which the radar device and / or the at least one object are moving relative to one another.

[0018] This approach is based at least on the realization that the temporal variation is relatively sensitive to changes in the orientation between the radar device and the object. By taking the relative motion between the radar device and the object into account, the determination of the angular information can be further improved.

[0019] A further embodiment provides that a change in the distance between the radar device and the at least one object is determined by evaluating the received echoes and is taken into account when determining the angle information. If, for example, it is determined that a time difference between the transmission of the respective radio wave and the reception of the corresponding echo changes, e.g., lengthens or shortens, a change in the distance can be inferred. The change in the distance occurs, for example, because the object moves away from the radar device or the radar device moves away from the object, thereby increasing the distance, and / or because the object moves closer to the radar device or the radar device moves closer to the object, thereby decreasing the distance.By taking the change in distance between the radar and the object into account when evaluating the temporal variation of the received echoes, this at least helps prevent the angular information from being distorted by the relative motion between the radar and the object. This makes the angular information particularly reliable and accurate.

[0020] Another embodiment provides that when evaluating the received echoes generated by the reflections of the radio waves emitted at several different frequencies on at least one object, a shape of the respective echo is determined and taken into account. Thus, not only is an extreme value of the echo, for example its maximum amplitude, determined and evaluated, but the course of the energy spectrum in the region of the extreme value and in particular around it is considered. Based on the shape of the respective echo, for example, it can at least contribute to determining the angle at which the object is positioned relative to the radar device, which makes the determination of the angular information even more precise.

[0021] Another embodiment comprises applying an angle determination criterion to determine the angle information. The angle determination criterion is based on machine learning methods. The angle determination criterion comprises, for example, an artificial neural network. The angle determination criterion was trained, for example, in a training process to determine the angle information. During the training process, the angle determination criterion is provided with, for example, training data, based on which the angle determination criterion learns to determine the angle information. The training data describes, for example, various emitted radio waves and their echoes on various objects. The angle determination criterion is thus an algorithm and / or comprises at least one rule based on which the angle information can be determined, i.e., for example, calculated.The trained angle determination criterion can be applied here at least to the received echoes. The angle determination criterion ultimately evaluates the temporal change of the received echoes as well as the evaluation of the received echoes generated by the reflections of the radio waves emitted at the various frequencies on the at least one object. This makes it clear that the angle information is determined precisely. In a preferred embodiment, when determining the at least one object, it is checked whether an amplitude of at least one of the received echoes is greater than a predetermined limit value. Only if this is the case is it assumed that the at least one object is located within the detection range.In other words, the radar device emits at least one energy pulse, i.e. the radio wave, which is reflected by at least one object in the detection range, and the reflected radio wave is received and detected by the radar device as an echo. If the amplitude of the reflected energy pulse and thus of the echo exceeds the predetermined limit, this is considered detection of an object. The amplitude corresponds to the aforementioned extreme value. The limit is preferably fixed. Consequently, it is fixed at which extreme value of the energy pulse and thus of the echo it is assumed that a relevant object is located in the detection range. Only when this check has taken place is the angular information relating to the detected object determined in a next step. This makes it particularly clear when the angular information is actually determined using the method according to the invention.For example, if an echo is received whose amplitude is less than or equal to the specified limit, this may result in no object being detected and therefore no angle information being determined.

[0022] Another preferred embodiment provides that object shape information is determined after the object has been determined. The object shape information describes a shape of the at least one determined object. The object shape information can thus be distinguished from the previously described shape of the respective echo. The object shape information relates to the object and describes whether it is, for example, round, square, or shaped differently. Based on the object shape information, a vehicle, in particular a motor vehicle, can be distinguished from a wall, a garbage can, or another object. Preferably, the determination of the angle information is permitted and carried out only after the object shape information has been determined.

[0023] The object shape information is determined by applying an object shape determination criterion to the received echoes, the evaluation of which was used to determine at least one object. The echoes that indicate or confirm the presence of the object are therefore used to determine the object information. The object shape determination criterion is applied precisely to these echoes. By applying the object shape determination criterion, the shape of the detected object can be determined. The object shape determination criterion comprises at least one algorithm and / or at least one rule, the application of which can determine the object shape, i.e. the shape of the detected object. This is particularly useful, for example, to be able to obtain details about the object, which can then at least influence the determination of the angular information or can improve the determination.

[0024] According to another embodiment, the object shape determination criterion is based on machine learning methods. The object shape determination criterion is, for example, an artificial neural network. The object shape determination criterion can be trained in a training process to be able to determine the shape of the object by evaluating received echoes. For this purpose, training data describing received echoes for differently shaped objects is provided, for example. Through the relationship between received echoes, for example a shape of an extreme value range of the received echo and / or a width of the extreme value and / or a height of the extreme value range, in particular the amplitude, a relationship between the respective received echo and the respective shape of the object can be learned.The object shape determination criterion is therefore designed to always accurately determine the shape of the object from which the radio wave was reflected when applied to received echoes.

[0025] Another embodiment includes taking the determined object shape information into account when determining the angle information. Only once the object's shape is known is the angle at which it is positioned relative to the radar device determined. The object shape information can therefore be one of the pieces of information to which the angle determination criterion is applied to determine the angle information. This leads to particularly precisely determined angle information.

[0026] A further exemplary embodiment provides that the determined angle information is provided for a function of the motor vehicle. It can, for example, be transmitted from the control device of the radar device, which determines the angle information, to a control unit in the motor vehicle that provides the function. The function is, in particular, a driver assistance system of the motor vehicle, such as a parking assistant, a distance control assistant, and / or a function for warning and / or taking into account objects in the vicinity of the motor vehicle. The function of the motor vehicle can be carried out based on the angle information and, if applicable, further information from the radar device.

[0027] The angle information is transmitted from the control device of the radar device to the control device of the motor vehicle, for example, by cable, in particular wired, and / or wireless, in particular wireless, within the motor vehicle.

[0028] In another exemplary embodiment, it is provided that, at least while the method is being carried out, radio waves are continuously emitted, in particular at several different frequencies, and the received echoes to the emitted radio waves are received and evaluated. It is therefore provided that the radar device continuously checks its surroundings and thus its detection range for the presence of at least one object. It can be provided that only after the object has been detected, for example, the received echoes detected one after the other and / or the echoes received at different frequencies of emitted radio waves are specifically detected by emitting the radio waves required for this purpose.It is also possible to concentrate on specific parts of the detection area, so that, for example, radio waves are specifically emitted into the area of ​​the detection area in which the detected object was approximately detected and is therefore expected.

[0029] A further aspect of the invention relates to a radar device for a motor vehicle, wherein radio waves are emitted and / or echoes are received only by means of a single respective antenna of the radar device. The radar device is designed to determine, by evaluating the received echoes, whether at least one object is located within a detection range of the radar device. Furthermore, if the at least one object is detected, it is designed to determine angle information that describes the angle at which the at least one object is located to the radar device. This is done by evaluating a temporal change in the received echoes and by evaluating the received echoes that were generated by reflections of radio waves that were emitted at several different frequencies from the at least one object.

[0030] A further aspect of the invention relates to a control device for a radar device, as described above. The control device is designed to carry out the method described above. The control device carries out the method described above, in particular an exemplary embodiment or a combination of exemplary embodiments of the described method.

[0031] The control device comprises, for example, a processor device. This can comprise at least one microprocessor, microcontroller, FPGA (Field Programmable Gate Array), and / or DSP (Digital Signal Processor). Furthermore, it can comprise program code, which can alternatively be referred to as a computer program product. The program code can be stored in a data memory of the processor device.

[0032] Another aspect of the invention relates to a motor vehicle with a radar device as described above. The motor vehicle is thus designed to carry out the method described above. The motor vehicle is, for example, a passenger car, a truck, a bus, a motorcycle, and / or a moped. The motor vehicle can have the described radar device, in particular the described control device.

[0033] Another aspect of the invention relates to a computer program product. The computer program product is a computer program. The computer program product comprises instructions that, when the program is executed by a computer, such as by the control devices, cause the computer to perform the corresponding steps of the method according to the invention.

[0034] The exemplary embodiments described in connection with the method according to the invention, individually and in combination with one another, apply accordingly, as applicable, to the radar device according to the invention, the motor vehicle according to the invention, the control device according to the invention, and the computer program product according to the invention. The invention encompasses combinations of the described exemplary embodiments.

[0035] Showing:

[0036] Fig. 1 is a schematic representation of a motor vehicle with a radar device; and Fig. 2 is a schematic representation of a signal flow graph of a method for determining angle information using a radar device for a motor vehicle.

[0037] Functionally identical elements are provided with the same reference numerals in the figures.

[0038] Fig. 1 shows a motor vehicle 1 having multiple radar devices 2. Here, one of the radar devices 2 is arranged in a front area of ​​the motor vehicle 1. Another radar device 2 is arranged in a rear area of ​​the motor vehicle 1. In addition, two radar devices 2 are arranged on the sides of the motor vehicle 1. A motor vehicle 1 with more or fewer radar devices 2 and / or with radar devices 2 distributed differently within the motor vehicle 1 is possible. The illustration in Fig. 1 is to be understood purely as an example.

[0039] The respective radar device 2 can have an antenna 3 and a control device 4. The method provided according to the invention is now carried out using a single respective antenna 3 of the radar device 2, wherein radio waves are transmitted and / or echoes are received by means of this antenna 3. This is to be understood that, for example, the method is carried out using a single antenna 3, which is a combined transmitting and receiving antenna. In the case of separate transmitting and receiving antennas, the method is carried out with two single antennas 3, one for transmitting the radio waves and the other for receiving the echoes. The radar device 2 is fully functional with regard to transmitting radio waves and receiving echoes. The radar device 2 can have multiple antennas 3. However, the single respective antenna 3, which transmits the radio waves and / or receives the echoes, is sufficient for the method.

[0040] The motor vehicle 1 can have a control unit 5 configured to provide a function 6 of the motor vehicle 1. The function 6 is, for example, a driver assistance system of the motor vehicle 1. A communication connection 7 can be provided between the radar device 2, preferably between the control device 4 of the radar device 2, on the one hand, and the control unit 5, on the other hand. This communication connection can be at least partially wireless and / or wired.

[0041] In the surroundings of the motor vehicle 1, there is an object 8, such as a pillar, a parked vehicle, a wall, a building, an object, a person, and / or an animal. The object 8 can be an obstacle for the motor vehicle 1. The object 8 is located in a detection zone 9 of the radar device 2 in the front area of ​​the motor vehicle 1.

[0042] Fig. 2 shows a schematic representation of a method for determining angle information 14 by means of the radar device 2. For the determination, for example, radio waves are transmitted and / or echoes are received only by means of the single respective antenna 3 of the radar device 2.

[0043] In a method step S1, it is determined whether at least one object 8 is located in the detection range 9 of the radar device 2. For this purpose, the received echoes are evaluated. Here, it is sketched as an example that, for example, an amplitude A of at least one of the received echoes, for which a curve 10 is sketched schematically here, is greater than a predetermined limit value 11. Here, location information x or a distance to the object 8 is plotted against the amplitude A. If the amplitude A is greater than the predetermined limit value 11, the at least one object 8 is assessed as being located in the detection range 9. If the amplitude A is less than or equal to the limit value 11, it is not assumed, for example, that the object 8 was detected in the detection range 9. The amplitude A can alternatively be referred to here as an extreme value.

[0044] In a method step S2, after the object 8 has been detected in method step S1, object shape information 13 can be determined. This information describes a shape of the at least one detected object 8. The object shape information 13 is determined by applying an object shape determination criterion 12 to the received echoes, by evaluating which the at least one object 8 was detected. The object shape determination criterion can be based on machine learning methods.

[0045] In a method step S3, the angle information 14 is determined if the at least one object 8 was determined in method step S1. The angle information 14 describes the angle at which the at least one object 8 is arranged to the radar device 2. The angle information 14 is determined by two evaluations. Firstly, a temporal change in the received echoes is evaluated. This is outlined here using two slightly different curve profiles for the time t1 and the time t2, in which, for example, a location Xi, X2, for which an extreme value was determined, differs. Secondly, the received echoes, which were generated by reflection of radio waves emitted at several different frequencies fi, f2, from the at least one object 8, are evaluated.This is illustrated here by two exemplary curves 10, which were determined for radio waves emitted at the frequency fi and the different frequency f2. The two curves 10 differ, for example, in the shape of the extreme value of the respective curve 10.

[0046] It can be provided that, when evaluating the temporal change, the direction 16 in which the radar device 2 and / or the at least one object 8 are moving relative to one another is determined. When determining the angular information 14, the direction 16 is taken into account. Alternatively or additionally, it can be provided that a change in a distance 17 between the radar device 2 and the at least one object 8 is determined by evaluating the received echoes and is taken into account when determining the angular information 14.

[0047] When evaluating the received echoes generated by the reflection of the radio waves emitted at the multiple different frequencies from at least one object 8, a shape of the respective echo can be determined and taken into account. Alternatively or additionally, an angle determination criterion 15, which can be based on machine learning methods, can be applied to determine the angle information 14. Furthermore, when determining the angle information 14 and thus, for example, when applying the angle determination criterion 15, the object shape information 13 determined in method step S2 can be taken into account.

[0048] The determined angle information 14 can be provided for function 6 of the motor vehicle 1 in a method step S4. For this purpose, it can be transmitted, for example, via the communication connection 7 from the control device 4 of the radar device 2, which, for example, carries out the method described above based on the data from the antenna 3, to the control device 5 of the motor vehicle 1. The function 6 can then be carried out based on the received angle information 14 and, if necessary, further information or data from the control device 4, such as the distance 17 and / or the object shape information 13.

[0049] At least during the implementation of the method, radio waves, in particular at several different frequencies, are preferably transmitted continuously, and the received echoes to the transmitted radio waves are received and evaluated. For this purpose, received echoes can be stored for a predetermined time window of, for example, several seconds or minutes, so that the consecutively received echoes can be correlated with each other, i.e., evaluated together.

[0050] Overall, the examples demonstrate machine learning of time-varying signals in connection with a radar device 2. The technical solution of the invention consists in expanding the information recorded by rangefinders, i.e., the radar device 2, namely its evolution over time. Historically, distance sensors are used to measure the object-sensor distance using the so-called threshold method. The sensor emits an energy pulse (Tx), which is reflected by objects 8 in the detection area 9 and recorded again by the sensor (Rx). The sensor here is the antenna 3 of the radar device 2. If the amplitude A of the reflected energy pulse (echo) exceeds a certain value (threshold 11), the radar device 2 detects it as a relevant obstacle.The next evolution here is the additional analysis of the shape of the reflected energy signal (object shape information) using machine learning algorithms. This method can be used to calculate information about the shape of the obstacle. In this technical solution of the present invention, a further extension of the previously used energy-sensor-signal analysis is performed, namely the analysis of the variation in the time dependence of the reflected energy signals in combination with the analysis of the difference in echo shapes when the sensor operates with two or more Tx frequencies.

[0051] This method is a type of sensor fusion approach. The reliability of the entire system, i.e., radar 2, is increased. Different measurement principles are used, which increases detection accuracy. This is based on mathematical methods such as statistics, the Dempster-Shafer evidence theory, or similar methods. The first input (evaluation) is a time-dependent sensor shape signal: This is an extension of a previous sensor signal analysis using machine learning, namely the analysis of the variation in the time dependence of the reflected energy signals. This refers to the evaluation of the temporal change of the received echoes described above. As learned from the analysis of the pure reflected energy signal, there are different time dependencies depending on the direction in which radar 2 approaches object 8 (this also applies when the object 8 in question is moving).If the angle is 0 degrees according to the angle information 14, almost no change is detectable, and thus the delta of echo (time t1) - echo (time t2) is almost zero. A correction for the different amplitudes (distance dependence) is assumed. The time-varying analysis is therefore very sensitive to the orientations between radar device 2 and object 8. It can be used to further improve the accuracy of the angle measurement (position of the obstacle = radial distance and angle = cylindrical coordinates).

[0052] The recorded sensor signals are stored here. Depending on the speed of the motor vehicle 1 (or the speed of the object 8 to be detected), a certain amount of time is required to compare the delta of two recorded signals. Delta means the signal to be analyzed by machine learning = signal (time t2> minus signal (time t2>-). The second input utilizes the Tx frequency dependence of the sensor shape signal: Here, antenna 3 operates at two or more different frequencies. The -3 dB aperture angle of a distance sensor (radar, ultrasound) = inversely proportional to the transmission frequency.

[0053] This means that the higher the frequency, the smaller the -3dB value. Therefore, comparing the shape of the sensor signal, i.e. the echo, with two or more transmit frequencies is a

[0054] Angular information 14 about the position of the detected object 8. In this case, where the two examples of 0 degrees and 45 degrees are taken, the delta of the two recorded echoes is a function of the angle.

Claims

Patent claims 1. A method for determining angle information (14) by means of a radar device (2) for a motor vehicle (1), wherein, for the determination, radio waves are transmitted and / or echoes are received, in particular, only by means of a single respective antenna (3) of the radar device (2), comprising: - determining (S1) whether at least one object (8) is located in a detection area (9) of the radar device (2) by evaluating the received echoes; and - if the at least one object (8) is detected, determining (S3) the angle information (14) which describes the angle at which the at least one object (8) is arranged to the radar device (2) by evaluating a temporal change in the received echoes and by evaluating the received echoes which were generated by reflections of radio waves which were emitted at several different frequencies at the at least one object (8).

2. Method according to claim 1, wherein when evaluating the temporal change it is determined in which direction (16) the radar device (2) and / or the at least one object (8) are moving relative to one another, and this is taken into account when determining the angle information (14).

3. The method according to claim 2, wherein a change in a distance (17) between the radar device (2) and the at least one object (8) is determined by evaluating the received echoes and is taken into account when determining the angle information (14).

4. Method according to one of the preceding claims, wherein, when evaluating the received echoes generated by the reflections of the radio waves emitted at the plurality of different frequencies on the at least one object (8), a shape of the respective echo is determined and taken into account.

5. Method according to one of the preceding claims, wherein an angle determination criterion (15) based on machine learning methods is used to determine the angle information (14).

6. Method according to one of the preceding claims, wherein, when determining the at least one object (8), it is checked whether an amplitude of at least one of the received echoes is greater than a predetermined limit value (11), and only if this is the case is it assumed that the at least one object (8) is located in the detection area (9).

7. Method according to one of the preceding claims, wherein after the object (8) has been determined, object shape information (13) which describes a shape of the at least one determined object (8) is determined by applying an object shape determination criterion (12) to the received echoes, by the evaluation of which the at least one object (8) was determined.

8. The method according to claim 7, wherein the object shape determination criterion (12) is based on machine learning methods.

9. The method according to claim 7 or 8, wherein the determined object shape information (13) is taken into account when determining the angle information (14).

10. Method according to one of the preceding claims, wherein the determined angle information (14) is provided for a function (6) of the motor vehicle (1), in particular for a driver assistance system of the motor vehicle (1).

11. Method according to one of the preceding claims, wherein at least during the execution of the method, radio waves are continuously emitted, in particular at several different frequencies, and the received echoes to the emitted radio waves are received and evaluated.

12. Radar device (2) for a motor vehicle (1), wherein in particular only by means of a single respective antenna (3) of the radar device (2) radio waves are transmitted and / or echoes are received, wherein the radar device (2) is designed to - to determine whether at least one object (8) is located in a detection area (9) of the radar device (2) by evaluating the received echoes; and - to determine an angle information (14) which describes the angle at which the at least one object (8) is arranged relative to the radar device (2), if the at least one object (8) is determined, by evaluating a temporal change in the received echoes and by evaluating the received echoes which were generated by reflections of radio waves which were emitted at several different frequencies at the at least one object (8).

13. Control device (4) for a radar device (2) according to claim 12, wherein the Control device (4) is designed to carry out a method according to one of the preceding claims.

14. Motor vehicle (1) with a radar device (2) according to claim 12.

15. A computer program product comprising instructions which, when executed by a computer, cause the computer to perform a method according to any one of claims 1 to 11.

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