Method for detecting the obstruction of a radar sensor and obstruction detection device

Abstract

The invention relates to a method for detecting (10) an obstruction (12) of a radar sensor (14) that at least partially impairs a radar signal (20, 20'). The invention further relates to an obstruction detection device.

Description

[0001] The invention relates to a method for occlusion detection according to claim 1. Furthermore, the invention relates to an occlusion detection device. State of the art

[0002] Radar sensors are susceptible to various forms of obstruction, such as dirt, icing, water, dust, and other deposits that can accumulate on the radar sensor and impair its measuring ability by attenuating, scattering, or reflecting the transmitted and received radar signals, resulting in reduced signal quality and accuracy.

[0003] When an obstruction occurs, it can cause the radar sensor to fail to correctly detect surrounding objects or to measure incorrect distances, speeds, or angles. A particularly problematic aspect is that obstructions are often not detected immediately, leading to continuously erroneous measurements. Radar sensors affected by such obstructions, for example, cannot reliably detect obstacles, which can lead to dangerous situations in safety-critical applications such as autonomous driving.

[0004] The effects of obstruction on radar sensors vary depending on the type and extent of the obstruction, as well as the environmental conditions. For example, a thin layer of water or dirt may only slightly impair the signals, while thicker layers or ice can significantly hinder signal transmission. Furthermore, spatially uneven obstruction across multiple antennas of the radar sensor can lead to inaccurate and unreliable measurements. Such spatially unevenly distributed obstructions arise, for example, from gravitational forces or flow conditions on the obscuring substances, particularly from thawing, sliding, or flow around them. Disclosure of the invention

[0005] According to the present invention, a method for obstruction detection with the features of claim 1 is proposed. This allows obstruction of the radar sensor to be detected early and even spatially measured. As a result, the radar sensor can be operated more reliably, safely, and accurately. An emerging obstruction can be detected earlier and more accurately. An incipient impairment of the radar sensor's measuring capability can be detected early by obstruction detection.

[0006] The radar sensor can be arranged in a device, in particular a mobile device, for example a vehicle. The vehicle can be a motorized vehicle, for example a car, or a two-wheeled vehicle, in particular a motorcycle. The radar sensor can be configured for object detection of environmental objects in the vicinity of the device. Environmental detection can include object recognition, semantic segmentation, and / or object classification of environmental objects in the vicinity of the device. The environmental objects can include living beings, for example people, plants, buildings, stationary facilities, for example infrastructure facilities, and / or mobile facilities, for example other vehicles.

[0007] Obscuration can be caused by the accumulation and / or deposition of substances, such as dirt, dust, mud, snow, and / or ice, on the radar sensor. Obscuration can lead to sensor blindness of the radar sensor. Obscuration can also be caused by precipitation on the radar sensor or on an external radome.

[0008] The occlusion can be spatially unevenly distributed. Spatially uneven occlusion can be due to spatially uneven layer height, spatial inhomogeneity (e.g., spatially uneven density or composition), or both. Spatially uneven occlusion can be related to a direction parallel and / or perpendicular to a direction of Earth's gravity.

[0009] The first and second transmitting antennas can be located close to each other along the direction of gravity, at an angle to it, or perpendicular to it.

[0010] The radar sensor can also have more than two transmitting antennas, for example, eight transmitting antennas, and / or more than two receiving antennas, for example, sixteen receiving antennas. The radar sensor's measurement capability can still be maintained even when obscuration begins, due to the spatial redundancy provided by the multiple transmitting and receiving antennas. Transmitting with the first and / or second transmission pattern can involve some or all of the radar sensor's transmitting antennas. The multiple transmitting and / or receiving antennas can be positioned adjacent to each other along, at an angle to, or perpendicular to the direction of Earth's gravity.

[0011] The transmission with the second transmission pattern can follow the transmission with the first transmission pattern in time.

[0012] The radar signals exhibiting the first and / or second transmission pattern can be transmitted by the first and second transmitting antennas. For the first transmission pattern, the number of frequency ramps of the transmitting antennas can be entirely different, or the number of frequency ramps of at least two of the transmitting antennas can be the same. The total number of frequency ramps, as the sum of all transmitting antennas involved in transmitting a given transmission pattern, can be the same or different.

[0013] In a preferred embodiment of the invention, it is advantageous to compare the first and second signal parameters and to make the detection of the occlusion dependent on this comparison. This allows for the detection of a spatially uneven distribution of the occlusion. Early detection of an incipient occlusion is possible.

[0014] A preferred embodiment of the invention is advantageous in which the comparison calculates a difference from at least the first and second signal parameters, and the detection of occlusion depends on this difference. Occlusion detection can be achieved by classifying the difference, for example, using a machine learning model. Occlusion detection can also be based on a comparison between the difference and a predefined difference threshold.

[0015] In a preferred embodiment of the invention, it is advantageous that if the difference exceeds a differential threshold, an occlusion of the radar sensor is inferred. Furthermore, the first and / or second signal parameters can also be evaluated independently of one another, for example, by comparing them with a predefined threshold. This allows the system to determine whether an occlusion is present at all. By evaluating the difference, for example, by comparing it with the differential threshold, a spatial distribution of the occlusion can also be determined.

[0016] In a preferred embodiment of the invention, the first and / or second signal parameter is a number of reflections, a detection density, and / or a signal power of the respective received radar signals. Detection density is understood to be the number of detections within a time window and / or a spatial area, in particular a distance dimension.

[0017] In an advantageous embodiment of the invention, the radar sensor comprises at least one first and one second receiving antenna. The reception of the transmitted and reflected radar signals, each exhibiting the respective transmission pattern, can occur simultaneously via at least the first and second receiving antennas. The first and second receiving antennas can be located adjacent to each other along the Earth's gravitational direction, at an angle to it, or perpendicular to it.

[0018] In a preferred embodiment of the invention, it is advantageous if the first and / or second signal parameter includes a correlation value of an angle estimate of the incoming radar signal. The angle estimate relates to the detection of an elevation angle and / or azimuth angle of the respective reflection.

[0019] In a specific embodiment of the invention, it is advantageous if the detection of the occlusion is carried out by separately evaluating the radar signals received by the first and second receiving antennas. This allows even spatially unequal occlusion present above the first and second receiving antennas to be detected.

[0020] In a preferred embodiment of the invention, it is advantageous if the transmission is repeated alternately with the first and second transmission patterns. This allows for the detection of the occlusion over a predetermined period.

[0021] Furthermore, the invention relates to a method for outputting status information which, depending on the detection of the obstruction by a previously described method for obstruction detection, provides information about the obstruction of the radar sensor. The status information can be transmitted to a user of the device containing the radar sensor.

[0022] The invention further relates to a method for removing obstruction from a radar sensor, depending on the detection of the obstruction by a previously described method for obstruction detection. The removal of the obstruction can be carried out by cleaning, flow around the sensor, and / or heat treatment.

[0023] Furthermore, the invention relates to a cover detection device with the features according to claim 10. The cover detection device can be arranged in the device.

[0024] Further advantages and advantageous embodiments of the invention will become apparent from the description of the figures and the illustration. Character description

[0025] The invention is described in detail below with reference to the illustration. Fig.Figure 1 shows a method for obstruction detection in a specific embodiment of the invention. The method for obstruction detection 10 of an obstruction 12 of a radar sensor 14 that at least partially impairs a radar signal comprises providing the radar sensor 14, which has at least a first transmitting antenna 16 and a second transmitting antenna 18, each for transmitting radar signals 20, and at least a first receiving antenna 22 and a second receiving antenna 24, each for receiving the reflected transmitted radar signals 20'. Furthermore, at least one first transmission pattern 30, formed by a predetermined number of temporally successive frequency ramps 28 per transmitting antenna, is transmitted 26 via at least the first and second transmitting antennas 16, 18.For example, the first transmission pattern 30 can include a first number i of frequency ramps 28 for transmission 26 via the first transmitting antenna 16 and a second number k of frequency ramps 28 for transmission 26 via the second transmitting antenna 18.

[0026] Furthermore, the emitted and reflected radar signals 20' exhibiting the first transmission pattern 30 are received via the first and second receiving antennas 22, 24 and at least one first signal parameter 34 of these received radar signals 20' is determined.

[0027] Furthermore, after the transmission 26 of the radar signals 20 exhibiting the first transmission pattern 30, a second transmission pattern 36, formed by a predetermined number of successive frequency ramps 28 per transmitting antenna and differing from the first transmission pattern 30, is transmitted 26' via at least the first and second transmitting antennas 16, 18, and the transmitted and reflected radar signals 20' exhibiting the second transmission pattern 36 are received 32' via the first and second receiving antennas 22, 24, and at least one second signal parameter 38 of the received radar signals 20' is determined. The dashed lines here and subsequently illustrate the time offset. The second transmission pattern 36 can include a third number j of frequency ramps 28 for transmission 26 via the first transmitting antenna 16 and a fourth number I of frequency ramps 28 for transmission 26 via the second transmitting antenna 18.

[0028] The transmission 26 of the radar signals 20 with at least the first and second transmission pattern 30, 36 is carried out in particular alternating repetitions 39.

[0029] The detection of an obstruction 12, which, for example, due to the gravitational force along the direction of Earth's acceleration G, covers the first transmitting antenna 16 and the first receiving antenna 22, is based on the first and second signal parameters 34, 38. The first and second signal parameters 34, 38 are first filtered by a filter unit 40 and then compared as filtered first and second signal parameters 34', 38' with a predefined threshold value 42. If the filtered first and / or second signal parameter 34', 38' exceeds the threshold value 42, a detection result 44 is output indicating that an obstruction 12 is present. Depending on this, status information 46 can be sent to provide information about the obstruction 12 of the radar sensor 14 and / or a removal 48 of the obstruction 12, for example by cleaning, heat treatment, or the like, can be initiated.

[0030] Preferably, a comparison 50 of the filtered first and second signal parameters 34', 38' is performed, for example, by calculating a difference 52 at least from the filtered first and second signal parameters 34', 38'. If the difference 52 exceeds a predefined difference threshold 54, a masking 12 and also a spatial inhomogeneity of the masking 12 can be inferred. Assume that the first number i of frequency ramps 28 is greater than the second number k of frequency ramps 28 and the third number j of frequency ramps 28 is less than the fourth number I of frequency ramps 28, while the sum of the first and second numbers i, k equals the sum of the third and fourth numbers j, I. If the first and second signal parameters 34, 38 are each, for example, a number of reflections N, and a difference 52 exists between the filtered first and second signal parameters 34', 38', respectively...If the difference 52 exceeds a predefined difference threshold 54, a spatial inhomogeneity in the masking 12 is detected. For example, if the filtered first signal parameter 34' is smaller than the filtered second signal parameter 38', then the masking 12 affects the first transmitting antenna 16 more strongly than the second transmitting antenna 18, and the masking 12 is thus spatially unevenly distributed.

[0031] By classifying 56 the difference 52 and the difference threshold 54, a degree of spatial inhomogeneity can be classified.

[0032] Depending on the previously performed comparison 50 of the filtered first and second signal parameters 34', 38' with the threshold 42, the acquisition result 44 may further include the information that an occlusion 12 of the first transmitting antenna 16 is stronger than an occlusion 12 of the second transmitting antenna 18, or that the first transmitting antenna 16 is occluded while the second transmitting antenna 18 is unoccluded.

[0033] The detection of the obstruction 12 can be achieved, in particular, by separately evaluating the radar signals 20' received by the first and second receiving antennas 22, 24. Upon reception 32 of the transmitted and reflected radar signals 20' exhibiting the first transmission pattern 30, the first signal parameter 34 can be determined via the first receiving antenna 22, and a third signal parameter 58 via the second receiving antenna 24. Similarly, upon reception 32 of the transmitted and reflected radar signals 20' exhibiting the second transmission pattern 36, the second signal parameter 38 can be determined via the first receiving antenna 22, and a fourth signal parameter 60 via the second receiving antenna 24. The detection result 44 can thus be calculated depending on the first, second, third, and fourth signal parameters 34, 38, 58, and 60.This also allows partial obstruction of the radar sensor 14 and / or spatial inhomogeneity in the obstruction 12 of the first and second receiving antennas 22, 24 to be detected.

[0034] The processing of the third and fourth signal parameters 58, 60 can be carried out analogously to the processing of the first and second signal parameters 34, 38, such as filtering by the filter unit 40, which calculates the filtered third and fourth signal parameters 58', 60' and the comparison 50' of the filtered third and fourth signal parameters 58', 60', by, for example, calculating a difference 52' at least from the filtered third and fourth signal parameters 58', 60' and an evaluation against the specified difference threshold 54.

Claims

[1] Method for detecting (10) an obstruction (12) of a radar sensor (14) that at least partially impairs a radar signal (20, 20'), Providing the radar sensor (14) which has at least one first and second transmitting antenna (16, 18) each for transmitting radar signals (20) and at least one receiving antenna (22, 24) each for receiving the reflected transmitted radar signals (20'), transmitting (26) at least one first transmission pattern (30) formed by a predetermined number of successive frequency ramps (28) per transmitting antenna (16, 18) radar signals (20) via at least one of the transmitting antennas (16, 18), Reception (32) of the emitted and reflected radar signals (20') exhibiting the first transmission pattern (30) via the at least one receiving antenna (22, 24) and determination of at least one first signal parameter (34) of these received radar signals (20'), Emitting (26) at least one radar signal (20') formed by a predetermined number of successive frequency ramps (28) per transmitting antenna (16, 18) and exhibiting a second transmission pattern (36) that differs from the first transmission pattern (30) via at least the other of the transmitting antennas (18, 16), Receipt (32) of the emitted and reflected radar signals (20') exhibiting the second transmission pattern (36) via the at least one receiving antenna (22, 24) and determination of at least one second signal parameter (38) of these received radar signals (20'), Detection of occlusion (12) depending on the first and second signal parameters (34, 38). [2] Method for detecting concealment (10) according to claim 1, characterized by , that a comparison (50) of the first and second signal parameters (34, 38) is performed and the detection of the occlusion (12) depends on the comparison (50). [3] Method for detecting concealment (10) according to claim 2, characterized by , that the comparison (50) calculates a difference (52) at least from the first and second signal parameters (34, 38) and the detection of the occlusion (12) depends on the difference (52). [4] Method for detecting coverts (10) according to claim 3, characterized by , that if the difference (52) exceeds a difference threshold (42), it is concluded that the radar sensor (14) is obscured (12). [5] Method for detecting concealment (10) according to any one of the preceding claims, characterized by , that the first and / or second signal parameter (34, 38) is a number of reflections (N), a detection density and / or a signal power of the respective received radar signals (20'). [6] Method for detecting concealment (10) according to any of the preceding claims, characterized bythat the radar sensor (14) has at least one first and one second receiving antenna (22, 24). [7] Method for detecting concealment (10) according to claim 6, characterized by , that the detection of the obstruction (12) is carried out by separate evaluation of the radar signals (20') received by the first and second receiving antennas (22, 24). [8] Method for detecting concealment (10) according to any one of the preceding claims, characterized by , that the first and / or second signal parameter (34, 38) includes a correlation value of an angle estimate of the incoming radar signal (20'). [9] Method for detecting concealment (10) according to any one of the preceding claims, characterized by , that the transmission (26) is repeated alternately with at least the first and second transmission pattern (30, 36). [10] Obscuration detection device for detecting an obscuration (12) of a radar sensor (14) that at least partially impairs a radar signal (20), comprising a radar sensor (14) comprising at least a first and second transmitting antenna (16, 18) for transmitting (26) radar signals (20) and at least one receiving antenna (22, 24) for receiving (32) the radar signals (20') and a control unit for executing the method for covering detection (10) according to any of the preceding claims.

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