Radar device and method for evaluating radar measurement signal of radar device

Abstract

The invention relates to a radar device having a plurality of radar devices, each of which is designed to generate and output radar measurement signals, and having a computing device, which is designed to carry out combined evaluation on the radar measurement signals of the radar devices, the computing device being designed to calculate the radar measurement signals of the radar devices, and the computing device being designed to calculate the radar measurement signals of the radar devices. When the radar measurement signals are subjected to combined analysis processing, selection of the radar measurement signals of the radar device is performed.

Description

Technical Field

[0001] This invention relates to a radar device and a method for analyzing and processing radar measurement signals from the radar device. Background Technology

[0002] Radar equipment emits radar signals that are reflected by objects in the radar channel. In a monostatic configuration, the reflected radar signals are received and analyzed by the same radar equipment to detect the distance, velocity, and angle of the reflecting object relative to the radar equipment.

[0003] In a bistatic configuration, the reflected radar signal can also be received by a second radar device, which is spatially separated from the first radar device. The distance, velocity, and angle of the reflecting object can be determined using the known distance between the two radar devices. The detected data is processed into a reflection list in each radar device and provided, for example, via a bus system.

[0004] A cooperative radar sensor system may consist of at least two radar sensors, or a computing unit with an extended total antenna array composed of subarrays, wherein the radar sensors or subarrays may be synchronized according to a synchronization scheme. An exemplary radar sensor system is disclosed in DE2019 / 10220238 A1. Summary of the Invention

[0005] This invention provides a radar device having the features of the independent claims and a method for analyzing and processing radar measurement signals from the radar device.

[0006] The preferred embodiments are the subject of the corresponding dependent claims.

[0007] Therefore, according to a first aspect, the present invention relates to a radar device having a plurality of radar devices, wherein each radar device is configured to generate and emit radar measurement signals; and having a computing device configured to perform combined analysis processing on the radar measurement signals of the radar devices, wherein the computing device is configured to perform selection of radar measurement signals of the radar devices during the combined analysis processing of the radar measurement signals.

[0008] According to a second aspect, the present invention relates to a method for analyzing and processing radar measurement signals from a radar device. Radar measurement signals are generated by multiple radar devices within the radar device. Furthermore, the radar measurement signals from the radar devices are subjected to combined analysis and processing, and during this combined analysis and processing, selection of radar measurement signals from the radar devices is performed.

[0009] Advantages of the present invention According to the present invention, radar measurement signals of the radar device are selected. This should be understood as: not all radar measurement signals of the radar device are considered in the combined analysis processing. Therefore, the present invention can utilize the adaptively dynamically generated aperture in the radar device.

[0010] To optimize and efficiently analyze and process radar measurement data from radar devices in radar equipment, sensors of different sizes can be paired based on the relative position of the current measurement point or target with respect to the radar equipment (e.g., the vehicle itself).

[0011] According to one embodiment, the radar device is a cooperative radar sensor system in which the radar elements are the individual radar sensors of the radar sensor system.

[0012] According to one embodiment, the radar device is a single radar sensor, in which the radar element is a subarray of the antenna elements of the radar sensor. Specifically, the radar device can be a radar device with sparse antenna apertures, preferably having subarrays (e.g., distributed via cables).

[0013] According to one embodiment of the radar device, the computing device is configured to completely ignore at least one radar measurement signal of the radar device, or consider only a subset of the radar device's transmit / receive channels, when performing combined analysis and processing of radar measurement signals. Here, "subset" should be understood as a proper subset, meaning it does not include all radar devices.

[0014] According to one embodiment of the radar device, the computing device is configured to perform angle determination for a pre-given subset of radar measurement signals by performing combined analysis and processing on the radar device.

[0015] According to one embodiment of the radar device, the sensor pairs of each radar unit can be simultaneously assigned to multiple angle segments and / or range segments for joint analysis and processing, for example, depending on the distance to the target, or divided within a physically existing radar unit, i.e., different antennas of the same radar unit can be assigned to different angle segments and / or range segments.

[0016] According to one embodiment of the radar device, the computing device is configured to select radar measurement signals from those radar devices that constitute the longest uninterrupted aperture for combined evaluation if the radar measurement signal has only one target (i.e., the target has been identified) in a specific range-velocity cell for a subset of the radar devices. Depending on the preprocessing method of the radar measurement data, where a target list is generated from the raw data during preprocessing, it is possible that not all radar devices have identified the same measurement point, for example, regarding range and velocity. Consequently, measurement data is lacking for cross-sensor angle analysis, resulting in gaps or unoccupied positions (holes) in the aperture. Based on which radar devices do not provide information, the longest meaningful aperture (e.g., the longest uninterrupted aperture) can be generated and improved from the existing radar measurement data. The same approach can also be performed, for example, depending on the target's range or angle of incidence, to avoid range-migration effects caused by aperture size.

[0017] According to one embodiment of the radar device, the computing device is configured to identify radar device misalignment by ignoring radar measurement signals from individual radar devices during combined analysis processing. For example, misalignment identification can be performed by sequentially excluding radar measurement data from each radar device from the total aperture and verifying the excluded radar devices with radar measurement data from the remaining aperture, or by correcting the measurement results of misaligned individual sensors.

[0018] According to one embodiment of the radar device, the computing device is configured to calibrate the radar device when an imbalance is detected in one of the radar devices. This can be achieved, for example, through an algorithm.

[0019] According to one embodiment of the radar device, the computing device is configured to perform single-target estimation based on a selection of radar measurement signals and calculate at least one quality value (Gütewert) of the single-target estimate. The computing device is also configured to perform combined analysis processing of all radar measurement signals only if the at least one quality value is below a pre-given threshold. For example, when performing angle analysis processing on a range-velocity cell that may contain more than one target, a quality criterion can be determined by using a sub-aperture with a small number of virtual channels (i.e., selecting radar measurement data from only some radar devices), thereby inferring whether the range-velocity cell may contain more than one target. Based on this criterion, it can be inferred whether further analysis processing is worthwhile, such as methods for reducing sidelobe levels, multi-target estimation, or more expensive target detection on the total aperture spectrum. This significantly reduces the computational overhead of angle estimation.

[0020] According to one embodiment of the radar device, the combined analysis and processing of all radar measurement signals includes single-target estimation or multi-target estimation.

[0021] According to one embodiment of the radar device, the computing device is configured to perform angle estimation when performing combined analysis and processing of radar measurement signals from the radar device. By selecting multiple radar devices, the aperture is increased, thereby improving the accuracy of the angle estimation.

[0022] Other advantages, features and details of the invention will become apparent from the following description, in which various embodiments are described in detail with reference to the accompanying drawings. Attached Figure Description

[0023] The attached diagram shows: Figure 1 A schematic block diagram of a radar device according to an embodiment of the present invention is shown; Figure 2 This illustrates illustrative angle / distance segmentation. Figure 3 Exemplary selections of radar measurement signals for the near-field region and the central far-field region are shown; Figure 4 An exemplary selection of radar measurement signals for edge segmentation is shown; Figure 5 An exemplary illustration shows a radar measurement signal with missing measurement results; Figure 6 An exemplary diagram is shown for determining misalignment of a radar device due to rotation; Figure 7 An exemplary diagram is shown for determining the misalignment of a radar system due to the displacement of the individual radar units relative to each other. Figure 8 An exemplary diagram is shown for determining the misalignment of a radar device due to the relative displacement of the radar device group to each other. Figure 9 An exemplary diagram illustrating the determination of quality values ​​is shown; Figure 10 A flowchart illustrating a method for analyzing and processing radar measurement signals from a radar device according to an embodiment of the present invention is shown.

[0024] In all the accompanying drawings, identical or functionally equivalent elements and devices are labeled with the same reference numerals. The numbering of method steps is for clarity and does not generally imply a specific temporal order. In particular, multiple method steps may be performed simultaneously. Detailed Implementation

[0025] Figure 1A schematic block diagram of a radar device 1 according to an embodiment of the present invention is shown, having a plurality of radar devices 21 to 2n, where n represents the total number of radar devices. However, the present invention is not limited to a specific number. The radar devices 21 to 2n can be arranged in a motor vehicle. The radar device 1 can be a cooperative radar sensor system, wherein the radar devices 21 to 2n are individual radar sensors. The radar device 1 can also be a single radar sensor, in which case the radar devices 21 to 2n are antenna subarrays of that radar sensor.

[0026] Each radar device here has a specific number of transmit / receive channels 311 to 31m, 3n1 to 3nk, where m and k represent the number of transmit / receive channels of the first radar device 21 or the nth radar device. Radar devices 21 to 2n can be designed differently or the same, i.e., in particular having the same number or at least partially different numbers of transmit / receive channels 311 to 31m, 3n1 to 3nk.

[0027] Each radar device 21 to 2n is configured to generate and output a radar measurement signal. The radar measurement signal may at this time include radar data from all transmit / receive channels 311 to 31m, 3n1 to 3nk of the respective radar device 21 to 2n.

[0028] Radar device 1 also includes a computing device 4. This computing device can be an external device or a component of one or more radar devices 21 to 2n. The computing device 4 can be composed of components from any of the radar devices 21 to 2n, wherein these components can exchange data.

[0029] The computing device 4 may include a processor, microprocessor, integrated circuit, special-purpose circuit, or similar components. The computing device 4 may also include at least one storage device for storing data, particularly radar measurement data, and for storing program instructions.

[0030] The computing device 4 receives radar measurement signals from radar devices 21 to 2n and analyzes and processes them.

[0031] The computing device 4 can perform combined analysis and processing of radar measurement signals, for example, for performing angle estimation. The computing device 4 can select radar measurement signals from radar devices 21 to 2n.

[0032] For example, when performing combined analysis and processing of radar measurement signals, computing device 4 may ignore at least one radar measurement signal from radar devices 21 to 2n. Computing device 4 may also consider only a subset of the transmit / receive channels 311 to 31m and 3n1 to 3nk of radar devices 21 to 2n.

[0033] Figure 2The diagram illustrates the angular and range segments. Radar device 1 is located at the origin of a coordinate system with x and y axes. The surrounding area is divided into six segments 51 to 56: a near-field region 56, a central far-field region 53 around the x-axis, and two edge regions, or edge segments, on the left and right sides, respectively, 51, 52 or 54, 55. The invention is not limited to a specific number of segments; the number of segments can be greater than or less than six.

[0034] The computing device 4 can perform angle determination for a pre-given angle segment and range segment by combining and analyzing radar measurement signals from a pre-given subset of radar devices 21 to 2n.

[0035] Figure 3 An exemplary selection of radar measurement signals for the near-field region 56 and the central far-field region 53 is shown. In this exemplary case, five radar devices 21 to 25 are present, but the invention is not limited thereto.

[0036] For the near-field region 56, the radar measurement signals of radar devices 21 to 25 are analyzed and processed individually (selected 61 to 65). This can also be done, for example, as preprocessing within radar devices 21 to 25, and is particularly meaningful in the near-field region, since this region does not meet the far-field conditions due to the size of the cooperative total aperture.

[0037] For the central far-field region 53, the radar measurement signals from all radar devices 21 to 25 are combined (selection 66). The central far-field region 53 corresponds to the angular range from a larger distance close to the boresight.

[0038] Figure 4 Exemplary selections of radar measurement signals for edge segments 51, 52, or 54, 55 are shown. For the outer left edge segment 51, radar measurement signals from the two left-side radar devices 21, 22 are combined (selection 71). For the inner left edge segment 52, radar measurement signals from the two left-side radar devices 21, 22 and the left half of the transmit / receive channel of the middle radar device 23 (i.e., with respect to the antenna arranged further left) are combined (selection 72). For the inner right edge segment 54, radar measurement signals from the two right-side radar devices 24, 25 and the right half of the transmit / receive channel of the middle radar device 23 (i.e., with respect to the antenna arranged further right) are combined (selection 73). For the outer right edge segment 55, radar measurement signals from the two right-side radar devices 24, 25 are combined (selection 74).

[0039] Edge segments 51, 52, 54, and 55 are defined based on the far-field condition, i.e., the minimum distance from which analysis should be performed, or based on the distance migration effect along the aperture, i.e., segmentation with respect to angle. In this case, edge segments 51, 52, 54, and 55 are defined either as follows: such that they are not significantly affected by the far-field condition or distance migration, or as follows: such that the resulting effects can be computationally eliminated with acceptable overhead.

[0040] Using aperture A and wavelength The estimation of far-field conditions (at 77 GHz) is as follows: For distance migration along aperture A, the modulation bandwidth B, the speed of light c, and the angle of incidence are considered. Applicable to: Based on the two estimations described above, a smooth transition between apertures can also be achieved by defining more segments. The granularity of the corresponding apertures and the resulting segments is limited only by the location of the virtual antenna channel of the total aperture. Depending on the system scheme and data connections, these segments can also be processed in different locations, such as in one of radar units 21 to 2n, in the accumulator, or in the central unit, which can reduce the data rate required between system components.

[0041] Figure 5 An exemplary illustration shows a missing measurement result in the radar measurement signal. Here, some measurement data is missing from the radar measurement data of the fourth radar device 24. For example, the radar measurement signal is only for a subset of radar devices 21 to 25, i.e., only for radar devices 21 to 23 and 25, where a target is present in a specific range-velocity cell. Since not all radar devices 21 to 25 can provide data for a common angle estimation (e.g., for the fourth radar device 24, no target was detected in a specific range-velocity cell), there is a lack of data to perform a common angle estimation through the defined aperture. This results in a hole in the aperture.

[0042] This could be due to reasons such as targets with strongly angle-dependent backscattering cross-sections, or highly preprocessed data in which data has been discarded. In such cases, angle estimation with dynamic aperture can be performed instead of aborting angle analysis processing and, if necessary, recalling the results from individual radar units 21 to 25.

[0043] To this end, the computing device 4 selects radar measurement signals from a subset of radar devices 21 to 23 and 25 that constitute the longest uninterrupted aperture (sub-aperture) for combined analysis processing. In this case, this is the first three radar devices 21 to 23, corresponding to selection 75. The sub-aperture can be divided by sensor if necessary, or it can be divided within radar devices 21 to 25. Here, a mask can be created based on the available data of the total aperture, which is used to crop the relevant region from the steering matrix used for angle estimation, and then this relevant region is applied to the measurement data for angle analysis processing.

[0044] Figure 6 An exemplary illustration is shown for determining that radar devices 21 to 25 are misaligned due to rotation. In this case, the fifth radar device 25 has been twisted, i.e., misaligned.

[0045] Figure 7 An exemplary illustration is shown for determining that radar devices 21 to 25 are misaligned due to translation, wherein radar devices 21 to 25 are individually displaced relative to each other and individually subjected to credibility checks.

[0046] Figure 8 An exemplary illustration is shown for determining whether a radar device is misaligned due to lateral displacement in the x, y, or z direction, wherein certain groups of radar devices 21 to 25 are displaced relative to other groups of radar devices 21 to 25, or a reliability check is performed at different apertures.

[0047] The computing device 4 can identify radar devices 21 to 25 by ignoring the radar measurement signals of individual radar devices 21 to 25 during combined analysis processing. Figures 6 to 8 The misalignment is shown in one of the scenarios. The misalignment can be identified by analyzing the remaining aperture when there is no radar device 21 to be inspected, relative to the radar device 21 to 25 to be inspected.

[0048] If a target, preferably in the far field, is detected in the data of all radar devices 21 to 25, the misalignment of each radar device 21 to 25 or any sub-aperture can be detected by generating different sub-apertures, for example by ignoring one radar device 21 to 25 separately. Furthermore, recalibration can be performed.

[0049] Here, the misalignment can be corrected and / or recalibrated through calculation. At this point, a salient target can be selected, which is detected by the sub-aperture and the remaining aperture, or by each radar element 21 to 25 of the remaining aperture.

[0050] For misalignments in angle or due to rotation, angle estimation is performed on the remaining aperture and a single sensor or sub-aperture to be inspected. Misalignment can be detected and / or quantified by comparing and verifying the reliability of the two estimated angles. This relative misalignment can be verified and verified by permutation of the combined sub-apertures, inferring the radar device, sensor, or sub-aperture where the actual misalignment occurs. Using appropriate algorithms, the quantified misalignment can be converted, for example, into calculating a correction factor, and / or adjusting the calibration matrix, and / or reported to the user.

[0051] When using correction factors or adjusting the calibration matrix, the measurement results of the radar device, or of an off-center individual sensor or an off-center sub-aperture, can be corrected, thereby preventing the degradation of the overall aperture measurement results.

[0052] In the case of rotational misalignment, both spatial angles of the radar device 21 to 2n are detuned, and the detection or correction can be performed in both angular directions. When detecting lateral misalignment or z-axis misalignment, as when detecting tilting and rotation, all sub-apertures can be combined and replaced. For all sub-apertures, the measurement parameters range, velocity, and two spatial angles are recorded, and their reliability is verified, for example, by using a prominent target appearing in all radar measurement data or sub-aperture measurement data.

[0053] For example, by using spatial angles and distances, all targets can be entered into a Cartesian three-dimensional grid, which allows for the detection of possible offsets along the x, y, and z axes for a given radar device or sub-aperture, and the corresponding correction of the measurement results.

[0054] When a misalignment is detected in one of the radar devices 21 to 25, the computing device 4 can calibrate the radar devices 21 to 25.

[0055] exist Figure 6 In the example, the radar measurement data (aperture or selection 65) of the fifth radar device 25 can be additionally analyzed and processed so that the results can be verified for reliability, for example, by means of selection 72.

[0056] Figure 9 An exemplary illustration of determining a quality value is shown. The computing device 4 can perform angle estimation based on selected radar measurement signals and calculate at least one quality value for that angle estimate. The computing device 4 can be configured to perform combined analysis processing on all radar measurement signals only if the at least one quality value is below a pre-given threshold.

[0057] According to one embodiment of the radar device, the combined analysis processing of all radar measurement signals includes multi-target estimation and / or methods for reducing sidelobe levels. Whether such combined analysis processing should be performed on the total aperture 81 (containing all radar elements 21 to 24) is determined by performing benefit estimations on smaller, computationally inexpensive virtual sub-apertures 82, 83, and 84.

[0058] With a large antenna aperture and multiple virtual channels, angle estimation, primarily multi-target estimation, is very expensive. Furthermore, the very high sidelobe levels are generated due to the "sparsity" of the total aperture 81. These sidelobe levels can be suppressed by algorithms before multi-target estimation to distinguish two or more targets with significantly different radar backscatter cross-sections located in the same range-velocity cell, and to prevent weaker targets from being masked by the sidelobes of stronger targets.

[0059] Multi-target estimation and algorithms for reducing sidelobe levels are computationally very expensive and should only be used when success is foreseeable. Therefore, the number of targets in the angular spectrum can be determined or estimated using the sub-apertures 82, 83, 84 of the individual sensors 21 to 24 or the corresponding virtual bistatic radar arrays 21 to 24, or all virtual apertures composed of two or more individual sensors 21 to 24, and decisions can be made using a multi-target estimator or target selection criteria (e.g., decision thresholds) on the total aperture 81, as well as using methods for reducing sidelobe levels.

[0060] An example of a multi-objective estimator is a bi-objective deterministic maximum likelihood estimator. Decision criteria could be, for example, selecting a decision threshold height above which peaks in the angular spectrum are identified as targets. Methods for reducing sidelobe levels could be so-called "compressed sensing" methods, such as the Iterative Adaptive Thresholding (IMAT) method, Clean, or similar methods.

[0061] To determine whether it is meaningful to use suppression techniques, multi-target estimators, and expensive detection methods on the computationally intensive total aperture 81, quality criteria, such as the magnitude of the principal angle correlation coefficient (Bartlett estimator), are determined on the computationally less computationally demanding sub-apertures. For the total aperture 81, amplitude A is plotted as the angle. The curve of the function is 85.

[0062] If the angular quality value, such as the correlation coefficient or other quality standard, is below a certain threshold, meaning the probability of only one target existing in the spectrum is very small, or two targets are detected directly, then it is very likely that multiple targets 87 and 88 located at different angles exist in this range-velocity cell. For the total aperture 81 and the smaller sub-aperture 82, the amplitude A is plotted as the angle. The curve of the function is 86.

[0063] The computing device 4 can thus determine whether it is necessary to perform subsequent high-resolution angle reconstruction, use a multi-target estimator, adjust the decision criteria or the detection technique based on the entire aperture, and whether it is worthwhile to reduce the computational overhead of the sidelobe level, or whether it is sufficient to use a single-target estimator on the entire aperture.

[0064] Figure 10 A flowchart is shown for a method of analyzing and processing radar measurement signals from radar device 1. This method can be performed using radar device 1 as described above.

[0065] In the first step S1, radar measurement signals are generated by multiple radar devices 21 to 2n of radar equipment 1.

[0066] In the second step S2, the radar measurement signals of radar devices 21 to 2n are combined and analyzed. During the combined analysis and processing of the radar measurement signals, the radar measurement signals of radar devices 21 to 2n are selected.

[0067] Here, when performing combined analysis and processing of radar measurement signals, the radar measurement signals of at least one radar device can be completely ignored, or only a subset of the transmit / receive channels of the radar device can be considered.

[0068] Angle determination can be performed for pre-given angle segments and / or range segments by combining and analyzing radar measurement signals from a pre-given subset of radar devices.

[0069] In addition, radar devices with the longest uninterrupted aperture can be selected for combined analysis and processing.

[0070] In addition, it can identify radar device malfunctions and correct them when necessary.

[0071] Furthermore, angle estimation can be performed based on the selection of radar measurement signals, and at least one quality value of the angle estimate can be calculated. Combined analysis processing of all radar measurement signals is only performed if the at least one quality value is below a pre-given threshold.

Claims

1. Radar equipment (1), having: Multiple radar devices (21-2n), among which, Each radar unit (21-2n) is configured to generate and output radar measurement signals; The computing device (4) is configured to perform combined analysis and processing on the radar measurement signals of the radar device (21-2n). The computing device (4) is configured to select the radar measurement signal of the radar device (21-2n) when performing combined analysis and processing on the radar measurement signal.

2. The radar device (1) according to claim 1, wherein, The computing device (4) is configured to completely ignore at least one radar measurement signal of one of the radar devices (21-2n) when performing combined analysis processing on the radar measurement signals, or to consider only a subset of the transmit / receive channels (311-31m, 3n1-3nk) of the radar devices (21-2n).

3. The radar device (1) according to claim 2, wherein, The computing device (4) is configured to perform angle determination for a pre-given subset of radar measurement signals from the radar device (21-2n) by performing combined analysis and processing.

4. The radar device (1) according to any one of the preceding claims, wherein, The computing device (4) is configured such that if the radar measurement signal has a target in a specific range-velocity unit for only a subset of the radar devices (21-2n), the radar measurement signals of the following radar devices (21-2n) in the subset of the radar devices (21-2n) are selected for the combined analysis processing: the radar devices constitute the longest uninterrupted aperture.

5. The radar device (1) according to any one of the preceding claims, wherein, The computing device (4) is configured to identify the misalignment of the radar devices (21-2n) by ignoring the radar measurement signals of each radar device (21-2n) during the combined analysis process.

6. The radar device (1) according to claim 5, wherein, The computing device (4) is configured to calibrate the radar device (21-2n) when an imbalance is detected in one of the radar devices (21-2n).

7. The radar device (1) according to any one of the preceding claims, wherein, The computing device (4) is configured to perform single-target estimation based on the selection of the radar measurement signals and calculate at least one quality value of the single-target estimation, wherein the computing device (4) is further configured to perform combined analysis processing on all radar measurement signals only when the at least one quality value is lower than a pre-given threshold.

8. The radar device (1) according to claim 7, wherein, The combined analysis and processing of all radar measurement signals includes multi-target estimation.

9. The radar device (1) according to any one of the preceding claims, wherein, The computing device (4) is configured to perform angle estimation when performing combined analysis and processing of the radar measurement signals of the radar device (21-2n).

10. The radar device (1) according to any one of the preceding claims, wherein, The radar device (1) is a cooperative sensor system, and the radar apparatus (21-2n) is a radar sensor.

11. The radar device (1) according to any one of claims 1 to 9, wherein, The radar device (1) is a radar sensor, and the radar apparatus (21-2n) is a subarray of the antenna elements of the radar sensor.

12. A method for analyzing and processing radar measurement signals from a radar device (1), comprising the following steps: (S1) radar measurement signals are generated by multiple radar devices (21-2n) of the radar equipment (1); The radar measurement signals of the radar device (21-2n) are combined and analyzed (S2), wherein, when the radar measurement signals are combined and analyzed, the selection of radar measurement signals of the radar device (21-2n) is performed.

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