Method for operating an ultrasonic sensor device for monitoring a bottom region of a motor vehicle, computer program product, computer-readable storage medium and ultrasonic sensor device

Abstract

The invention relates to a method for operating an ultrasonic sensor device (2) for monitoring a bottom region (12) of a motor vehicle (1), wherein ultrasonic signals (U) are emitted into the bottom region (12) by means of at least one ultrasonic sensor (4, 5, 6, 7) of the ultrasonic sensor device (2) and reflected ultrasonic signals (U) are received and evaluated. After the motor vehicle (1) is parked at a first point in time (t1), a reference measurement curve (13) for the bottom region (12) is generated and stored on the basis of at least one ultrasonic signal (U), wherein a measurement region (18) is determined in the reference measurement curve (13) in which the monitoring process of the bottom region (12) is analyzed and the measurement region (18) is determined on the basis of an attenuation time (16) of the ultrasonic sensor (4, 5, 6, 7) and a ground reflection (19) on the ground (11). Furthermore, the invention relates to a computer program product, a computer-readable storage medium and an ultrasonic sensor device (2).

Description

Technical Field

[0001] This invention relates to a method for operating an ultrasonic sensor device for monitoring the underside region of a motor vehicle by means of an ultrasonic sensor device in the vehicle, wherein ultrasonic signals are emitted into the underside region by means of at least one ultrasonic sensor device, and wherein reflected ultrasonic signals are received and evaluated by means of an ultrasonic sensor. Furthermore, this invention relates to computer program products, computer-readable storage media, and ultrasonic sensor devices. Background Technology

[0002] Inspecting or monitoring the underside of a vehicle before it leaves is a necessary task for the vehicle itself during autonomous driving. Specifically, dangerous objects such as children or animals should be detected before the vehicle leaves to prevent it from leaving and causing harm to these objects. Various sensor systems can be used to detect objects. For example, cameras or lidar sensors can be used, although they can only operate with additional precautions due to challenging environmental conditions. Alternatively or additionally, radar sensor devices and / or ultrasonic sensor devices can also be used. Especially with ultrasonic sensor devices, lateral spatial resolution is often not achievable. Therefore, multiple reflections from the underside cannot be distinguished from reflections of the relevant object. Furthermore, this method can produce masking phenomena, meaning that, for example, the vehicle's wheels produce a stronger reflection than the actual object itself, and the object is then no longer detectable in the ultrasonic signal.

[0003] Furthermore, during calibration, it can be assumed in principle that the distance between the sensor and the road surface is constant, as calibration typically only addresses the road surface's attenuation time and reflection. However, existing solutions do not allow for changes in the vehicle's loading condition. In particular, the loading condition can significantly impact calibration. Moreover, different vehicle models have varying heights between the vehicle's undercarriage and the road surface.

[0004] Document WO 03 / 016941A2 discloses an echo signal monitoring device, which includes a plurality of transceiver units for transmitting signals and receiving echoes reflected from an external object, and an evaluation unit for estimating the distance between the monitoring device and the external object by means of the received echoes, wherein the device has an operating state for calculating the relative positions of the transceiver units to each other based on the reflected echoes.

[0005] DE 10 2018 / 130914A1 relates to a method for operating an ultrasonic sensor device, wherein ultrasonic signals are emitted into a ground area of ​​a motor vehicle and received, and an object is detected by means of an electronic computing device based on the received ultrasonic signals, wherein a first ultrasonic signal is received in the ground area at a first time point, a second ultrasonic signal is received at a second time point, and the first ultrasonic signal, as a first reference curve, and the second ultrasonic signal, as a comparison curve, are compared with each other, and based on the comparison, a first threshold region is generated according to the received first amplitude, and an object is detected when a predetermined first number of the received first amplitudes of the comparison curve are detected outside the threshold region.

[0006] DE 10 2017 208 268 B3 discloses a method for determining the loading status of a vehicle and / or for determining the installation height of at least one ultrasonic sensor of the vehicle, wherein the ultrasonic sensor of the vehicle has at least one first operating mode and a second operating mode, the second operating mode differing from the first operating mode in at least one operating parameter. The ultrasonic sensor operates in the first operating mode to detect the environment surrounding the vehicle. This first operating mode may also be referred to as normal operation or measurement operation. The ultrasonic sensor operates in the second operating mode to determine the loading status of the vehicle and / or determine the installation height. It is configured that, in the second operating mode, the ultrasonic sensor is controlled such that, compared to the first operating mode, the ultrasonic sensor has increased acoustic radiation toward the road (i.e., the ground on which the vehicle is located). To determine the loading status of the vehicle and / or determine the installation height, the echo signal (so-called ground echo) reflected from the road surface of the ultrasonic signal emitted by the ultrasonic sensor is evaluated. Summary of the Invention

[0007] The object of this invention is to provide a method, a computer program product, a computer-readable storage medium, and an ultrasonic sensor device by means of which more reliable monitoring of the underside area of ​​a motor vehicle can be performed.

[0008] This objective is achieved by the method, computer program product, computer-readable storage medium, and ultrasonic sensor device according to the independent claims. Advantageous forms of the embodiments are specified in the dependent claims.

[0009] One aspect of the invention relates to a method for monitoring the underside region of a motor vehicle using an ultrasonic sensor device. Ultrasonic signals are transmitted to the ground region using at least one ultrasonic sensor in the ultrasonic sensor device, and reflected ultrasonic signals are received and evaluated using the ultrasonic sensor. After the motor vehicle stops at a first time point, a reference measurement curve for the underside region is generated based on at least one ultrasonic signal and stored.

[0010] A process for evaluating the monitoring of the bottom region within a reference measurement curve is provided, wherein the measurement region is determined based on the attenuation time of the ultrasonic sensor and ground reflection on the ground.

[0011] This allows for more reliable monitoring of the underside of motor vehicles.

[0012] Specifically, the measurement area is defined between the bottom of the vehicle and the ground area, particularly between the decay time and ground reflection. By taking into account the decay time and ground reflection, this measurement area can be reliably determined, allowing for improved monitoring of the bottom area. Within this measurement area, objects can then be searched.

[0013] In an advantageous embodiment, after the vehicle is restarted, at a second time point later than the first time point, a comparison measurement curve is generated based on at least one additional ultrasonic signal, and a reference measurement curve is compared with the comparison measurement curve in the measurement area. Based on this comparison, monitoring of the bottom area is performed by means of the electronic computing device of the ultrasonic sensor device.

[0014] In a convenient embodiment, the height change between the bottom of the vehicle and the ground in the bottom region is determined based on comparison, and the height change is taken into account in the evaluation and monitoring, wherein the height change between a first time point and a second time point is determined.

[0015] This allows for reliable monitoring of the underside region of a motor vehicle. Specifically, the underside region is understood to refer to the area formed between the road surface where the vehicle is located and the vehicle's ground region. The proposed method creates the possibility of using ultrasonic sensor devices in different vehicle models, under different load conditions, and after vehicle body modifications. This provides greater flexibility for both fully autonomous operation (e.g., in so-called valet parking procedures) and assisted operation (where the load is particularly heavily influenced by vehicle occupants).

[0016] Specifically, the present invention therefore utilizes the fact that when a motor vehicle is parked, it can be assumed that no object is located in the bottom region. For this purpose, a reference measurement curve is generated after the motor vehicle has been parked, and thus in the absence of an object. As part of this, the height of the bottom of the motor vehicle relative to the road surface can be determined. When the motor vehicle restarts, ultrasonic signals are emitted again and a comparison measurement curve is generated. If an object is now located in the bottom region, this can be detected by comparison. Furthermore, another height can now be determined, which may be caused, for example, by a change in the loading state of the motor vehicle compared to a first time point. This change in height is then taken into account when searching for objects in the bottom region.

[0017] According to an advantageous form of the embodiment, ground reflection is determined from the reflected ultrasonic signal of a reference measurement curve, and a first height relative to the ground is determined based on the determined ground reflection at a first time point. Ground reflection is determined from another reflected ultrasonic signal of a comparison measurement curve, and a second height relative to the ground is determined based on the determined ground reflection at a second time point. The height change is determined by comparing the first and second heights. Specifically, the ground clearance of the ultrasonic sensor is thus determined. For this purpose, measurement signals from the ultrasonic sensor are recorded. When the vehicle is parked, it can be assumed that there are no objects in the critical area, allowing a first maximum value in the ultrasonic signal to be assigned to the road surface. In addition to this reflection, the duration of the attenuation time can also be determined. Based on these two points, the area used to evaluate the signal for bottom detection can now be adaptively determined. Furthermore, additional parameters can be derived from these two points and their amplitudes. In particular, for example, by determining the first height during the first time point and the second height during the second time point, changes in loading conditions can be reliably detected. This allows the method to become robust to load conditions, enabling reliable monitoring of the bottom area.

[0018] It is also advantageous to consider the decay time of the ultrasonic sensor when determining changes in height. Specifically, object detection cannot be performed in the region of decay time (meaning the ultrasonic transducer of the sensor device is still vibrating and therefore unsuitable for signal reception), and this is now taken into account. In particular, the ultrasonic sensor is therefore essentially "deaf" during the decay time. By taking this deafness into account, reliable monitoring of the underside of motor vehicles can be achieved.

[0019] It has also been demonstrated that it is advantageous to detect at least one first environmental condition when generating the reference measurement curve and / or at least one second environmental condition when generating the comparison measurement curve, and to consider both environmental conditions when determining height changes. In particular, environmental conditions have a significant impact on ultrasonic signals. For example, environmental conditions such as temperature or air humidity can significantly affect the corresponding measurement curves. By considering these environmental conditions, height changes can now be better determined, and object detection can be improved. This means that reliable monitoring of the bottom region can be achieved.

[0020] In another advantageous form of the embodiment, the ultrasonic signal is emitted by the at least one ultrasonic sensor to an area behind one wheel of the motor vehicle. Specifically, the motor vehicle may have multiple ultrasonic sensors distributed throughout the vehicle. Specifically, they are positioned behind a particular wheel. In particular, since the critical area of ​​the object being driven over is behind the wheel, it is advantageous to perform appropriate monitoring in this area. This allows the ultrasonic sensors to perform better monitoring of the underside area. In this case, the arrangement of the ultrasonic sensors can also be implemented on additional components of the motor vehicle, such as in the area of ​​the fender. Specifically, the ultrasonic sensors are oriented directly from the underside in the direction of the road surface.

[0021] Another advantage is that the ultrasonic sensor device has multiple ultrasonic sensors on the motor vehicle, which are used to monitor the underside area of ​​the vehicle. This allows the ultrasonic sensors to perform better monitoring of the underside area. This arrangement can also be implemented on different parts of the motor vehicle, such as in the fender area. In particular, the ultrasonic sensors are oriented directly from the underside in the direction of the road surface.

[0022] A further advantage is that the corresponding reference measurement curve and / or corresponding comparative measurement curve of one of the plurality of ultrasonic sensors is compared with at least one corresponding reference measurement curve and / or corresponding comparative measurement curve of another of the plurality of ultrasonic sensors, and verification is performed. If, for example, the ultrasonic sensor is covered by an object during the generation of the measurement curve, height change detection can still be performed based on the additional ultrasonic sensor. In particular, the verification of the ultrasonic sensor evaluation can then be performed sequentially. Thus, for example, if the plurality of ultrasonic sensors detect a suitable gap under the vehicle, but another ultrasonic sensor does not detect any gap, this can be verified, and corresponding countermeasures can be initiated, for example, generating a warning message for the vehicle user. This allows for reliable monitoring of the bottom area.

[0023] According to another advantageous form of the embodiment, objects in the measurement area that have been driven through during the generation of the reference measurement curve are considered during monitoring. If, for example, objects such as wood or stone are present in the bottom area during the generation of the reference measurement curve and have also been driven through, these objects can be additionally stored in the reference measurement curve as objects that can be driven through, and can also be taken into account when monitoring the bottom area when the vehicle leaves. Thus, extensive monitoring of the bottom area can be achieved.

[0024] Furthermore, it has been shown that determining the measurement region within a reference measurement curve is advantageous, where the sample values ​​within the measurement region are weighted more heavily compared to samples outside the region. Specifically, an adaptive weighting of sample values ​​in the evaluation measurement signal is therefore proposed for bottom region monitoring to achieve reliable object detection. Challenges in object detection arise from varying distances between the object and the ground, as well as the object's different reflection behaviors. For example, soft objects in ultrasonic signals are more likely to "swallow" the echo, while hard objects generate new reflection peaks. This effect can be better handled with appropriate weighting, and thus object detection can be significantly improved.

[0025] According to another advantageous form of the embodiment, the ground reflection region and decay time of the ultrasonic sensor are determined in a reference measurement curve, wherein the weighting of sample values ​​in the ground reflection region is increased compared to sample values ​​during the decay time. Specifically, since the ultrasonic sensor is essentially deaf during the decay time, there is little information related to monitoring the bottom region present there. On the other hand, potential information exists in the ground reflection region, causing the weighting to increase in the determined ground reflection region. This allows for improved assessment and monitoring of the bottom region.

[0026] It has also been demonstrated that performing nonlinear weighting over the decay time, measurement area, and ground reflection area is advantageous for monitoring the bottom region. Specifically, information about the object from the decay time, and particularly from the ground reflection area, can be integrated into object detection, and sample values ​​can be weighted across the entire evaluation range. The entire evaluation range is defined specifically from the decay time through the measurement area to the ground reflection area. In particular, the impact of each region on object detection is now considered. During the decay time, almost no information about the object is found, but in the region between the decay time and the ground reflection—in other words, in the measurement area—most information is found, and significantly less information exists within the ground reflection area itself. Depending on where the object is located, such as very close to the sensor or the decay time, or very close to the ground reflection, object information can be distributed differently. For this purpose, an adaptive selection of weighting is proposed. For this purpose, both the decay time and the ground reflection are measured during calibration, where, in addition to amplitude and location, fluctuations in the corresponding peaks and / or their widths during the calibration period are of particular interest. When examining the bottom, the height of the ground reflection can be examined in addition to the decay time. Depending on the value of the feature, nonlinear weighting of the sampling points can be applied, which can significantly increase sensitivity and robustness of object detection.

[0027] This method is particularly known as the computer-implemented method.

[0028] Another aspect of the invention relates to a computer program product having program code means stored in a computer-readable storage medium so that, when the computer program product is executed on a processor of an electronic computing device, the method for monitoring a bottom region according to the foregoing aspect is performed.

[0029] Another aspect of the present invention relates to a computer-readable storage medium having a computer program product according to the foregoing aspects. The computer-readable storage medium can be specifically designed as part of an electronic computing device.

[0030] Electronic computing devices specifically include circuitry required to process computer program products, such as integrated circuits, processors, and other electronic components.

[0031] Another aspect of the invention relates to an ultrasonic sensor device for monitoring the underside region of a motor vehicle, having at least one ultrasonic sensor and an electronic computing device, the ultrasonic sensor device being designed to perform the method according to the foregoing aspect. In particular, the method is performed by means of the ultrasonic sensor device.

[0032] Another aspect of the invention relates to a motor vehicle having an ultrasonic sensor device according to the foregoing aspects. The motor vehicle can be at least semi-autonomous, and particularly fully autonomous.

[0033] Advantageous forms of embodiments of this method are considered advantageous forms of embodiments of ultrasonic sensor devices and motor vehicles. The ultrasonic sensor devices and motor vehicles have specific features for this purpose, enabling the execution of the method or its advantageous embodiments.

[0034] Other features of the invention can be collected from the claims, drawings, and description of the drawings. Features and combinations of features referenced in the above description, as well as features and combinations of features referenced in the following description of the drawings and / or shown individually in the drawings, can be used not only in the combinations indicated but also in other combinations without departing from the scope of the invention. Therefore, the invention is also intended to be considered to include and disclose embodiments not explicitly shown and explained in the drawings, but which can be generated and produced from the explained embodiments by individual combinations of features. Therefore, embodiments and combinations of features that do not have all the features of the initially formulated independent claims should also be considered disclosed. Embodiments and combinations of features that exceed or differ from the combinations of features set forth in the reverse references to the claims should also be considered disclosed, particularly those disclosed by the above embodiments. Attached Figure Description

[0035] Figure 1 A schematic side view of an embodiment of a motor vehicle having an ultrasonic sensor device is shown;

[0036] Figure 2 A schematic diagram of the reference measurement curve is shown;

[0037] Figure 3 A schematic diagram comparing the measurement curves is shown; and

[0038] Figure 4 Another schematic diagram showing multiple reference measurement curves is presented.

[0039] In the accompanying drawings, elements that are identical or have the same function have the same reference numerals. Detailed Implementation

[0040] Figure 1A schematic side view of an embodiment of a motor vehicle 1 having an ultrasonic sensor device 2 is shown. The ultrasonic sensor device 2 specifically includes an electronic computing device 3 and at least one ultrasonic sensor 4, 5, 6, or 7. In the following exemplary embodiments, the ultrasonic sensor device 2 includes a first ultrasonic sensor 4, a second ultrasonic sensor 5, a third ultrasonic sensor 6, and a fourth ultrasonic sensor 7. The ultrasonic sensor device 2 may also have more than four ultrasonic sensors 4, 5, 6, or 7. In the exemplary embodiments, this is purely exemplary and is in no way intended to be exhaustive.

[0041] In addition, Figure 1 As shown, the first ultrasonic sensor 4 can be arranged, for example, in the front region of the vehicle 1, such as on the fender of the vehicle 1. In the present case, the second ultrasonic sensor 5 is located behind the front wheel 8. The third ultrasonic sensor 6 is arranged behind the rear wheel 9. The fourth ultrasonic sensor 7 is arranged at the rear of the vehicle 1, for example on the fender of the vehicle 1. In this case, the positioning of the different ultrasonic sensors 4, 5, 6, 7 should also be understood as purely exemplary. However, preferably, at least some of the ultrasonic sensors 4, 5, 6, 7 are arranged in front of and behind the respective wheels 8, 9, because these represent the key areas of the object being driven over. It is also practical for the ultrasonic sensors 4, 5, 6, 7 to be oriented directly from the bottom 10 of the vehicle 1 along the direction of the ground 11 on which the vehicle 1 is located. In particular, the bottom region 12 is formed between the bottom 10 and the ground 11.

[0042] In the method for monitoring the bottom region 12 of a motor vehicle 1, at least one ultrasonic sensor 4, 5, 6, 7 of the ultrasonic sensor device 2 transmits ultrasonic signals U( Figure 2 The reflected ultrasonic signal U is emitted into the bottom region 12 and received and analyzed by means of at least one ultrasonic sensor 4, 5, 6, 7, wherein the reflected ultrasonic signal U is emitted at the first time point t1 of the motor vehicle 1. Figure 2 After parking, the reference measurement curve 13 for the bottom region 12 ( Figure 2 The measurement region 18 is generated and stored based on at least one ultrasonic signal U. The measurement region 18 is determined in the reference measurement curve 13. Figure 2 The monitoring process of the bottom region 12 in this area is evaluated, based on the attenuation time 16 of ultrasonic sensors 4, 5, 6, and 7. Figure 2 ) and ground reflection 19 on ground 11 ( Figure 2 To determine the measurement area 18.

[0043] Additionally, after vehicle 1 restarts, at a second time point t2 later than the first time point t1 ( Figure 3At this point, a comparative measurement curve 14 can be generated based on at least one additional ultrasonic signal U. Figure 3 The reference measurement curve 13 is compared with the comparison measurement curve 14, and based on the comparison, the monitoring of the bottom region 12 is performed by means of the electronic computing device 3.

[0044] It is also set that, based on comparison, the height change Δh between the bottom 10 of the motor vehicle 1 and the ground 11 in the bottom region 12 is determined, and the height change Δh is taken into account in the evaluation and monitoring, wherein the height change Δh between the first time point t1 and the second time point t2 is determined.

[0045] Figure 2 A schematic diagram of the reference measurement curve 13 generated at the first time point t1 is shown. Specifically, the sample value 15 of the ultrasonic signal U is plotted on the horizontal axis. Specifically, the corresponding amplitude of the ultrasonic signal U is shown on the vertical axis. The reference measurement curve 13 includes the decay time 16, the ground reflection area 17, and the measurement area 18.

[0046] Specifically, the ground reflection area 18 has a peak value as ground reflection 19, which represents, for example, the ground itself. Specifically, based on the measurement area 18, a first height h1 can be determined, and the first height h1 between the bottom of the vehicle body 10 and the ground 11 can be determined during a first time point t1. Specifically, a second height h2 can be determined during a second time point t2. Figure 3 ).

[0047] In particular, Figure 2 Typical signals from ultrasonic sensors 4, 5, 6, and 7 are shown when used in the underside region 12 of a motor vehicle 1. Specifically, two regions can be clearly identified: first, the attenuation time region 16 at the beginning of the signal, and then a clear signal deflection at a later time. This signal deflection can be attributed to ground reflection 19. Therefore, the interval between these two signal characteristics determines the region to be evaluated, particularly the measurement region 18, for object detection in the underside region 12.

[0048] Specifically, the end of decay time 16 is indicated by reference numeral 20 in sample value 15, and the peak value of ground reflection 19 is indicated by reference numeral 21 in sample value 15. This is the case at the first time point t1.

[0049] Figure 3 A schematic diagram of the comparison measurement curve 14 at the second time point t2 is shown. (Compared to...) Figure 2 Compared to the ultrasonic signal U, the difference in attenuation time 16 is already significant. Furthermore, it can be seen more clearly that the shape and distance to ground reflection 19 are different from... Figure 2Significantly different. Specifically, the end of decay time 16 is identified by reference numeral 22 in sample value 15, and the peak of ground reflection 19 is identified by reference numeral 23 in sample value 15. This is shown here at the second time point t2. For illustrative purposes, it is also shown according to... Figure 2 The accompanying figures are labeled 20 and 21.

[0050] If you want to use Figure 2 If the same evaluation or the same evaluation area or measurement area 18 is used, this will cause errors in the determination, and thus also cause false detection or failure to detect objects.

[0051] Therefore, it is specifically proposed that, in the reflected ultrasonic signal U of the reference measurement curve 13, the ground reflection 19 of the ground 11 is determined, and the first height h1 relative to the ground 11 is determined based on the ground reflection 19 determined at the first time point t1. In the other reflected ultrasonic signal U of the comparison measurement curve 14, the ground reflection 19 of the ground 11 is determined, and the second height h2 relative to the ground 11 is determined based on the ground reflection 19 determined at the second time point t2. The height change Δh is determined by comparing the first height h1 and the second height h2.

[0052] As already mentioned, when determining the height change Δh, the attenuation time 16 of ultrasonic sensors 4, 5, 6, and 7 is taken into account. Specifically, it can be further provided that at least one first environmental condition is detected when generating the reference measurement curve 13 and / or at least one second environmental condition is detected when generating the comparison measurement curve 14, and the first and / or second environmental conditions are taken into account when determining the height change Δh. For example, environmental conditions can be temperature or air humidity values. It can also be provided that the corresponding reference measurement curve 13 and / or corresponding comparison measurement curve 14 of the plurality of ultrasonic sensors 4, 5, 6, and 7 are compared and verified with at least one corresponding reference measurement curve 13 and / or corresponding comparison measurement curve 14 of another ultrasonic sensor 4, 5, 6, and 7. In particular, when generating the reference measurement curve 13, objects that can be driven over may also be considered.

[0053] Figure 4 Another schematic diagram is shown, specifically showing several different reference measurement curves 13. In particular, several different decay times 16 for acquiring the reference measurement curves 13 are shown. Additionally, several ground reflection zones 17 can be identified.

[0054] In particular, Figure 4Monitoring of the bottom region 12 is shown to be performed only in a very limited portion of the signal, because, for example, only 20 cm is typically available between the ultrasonic sensors 4, 5, 6, 7 and the ground 11. This region is further limited by the attenuation time 16 and the ground reflection region 17. Although little information about the object is typically obtained during the attenuation time 16, exceptions occur because reflections from the object can also be included in the ground reflection region 17 when the object is in contact with or only a few centimeters away from the ultrasonic sensors 4, 5, 6, 7. Since the reflection amplitude of the ground reflection 19 can be significantly higher than that of the at-risk object, a corresponding method has been proposed. To integrate the information about the object from the attenuation time 16, but particularly from the ground reflection 19, into object detection, it is recommended to weight the sample values ​​15 24 across the entire evaluation region. The evaluation region is specifically defined by the attenuation time 16, the measurement region 18, and the ground reflection region 17. The influence of the respective regions on object detection is considered.

[0055] As already described, there is generally almost no information about the object during the decay time 16. However, most information is found in the region between the decay time 16 and the ground reflection 19, and significantly less again in the ground reflection 19 itself. The object information can be distributed differently depending on the object's location. For this purpose, an adaptive selection of weighting 24 is proposed. For this purpose, the decay time 16 and the ground reflection 19 are measured during the generation of the reference measurement curve 13. In addition to amplitude and location, the fluctuations in the corresponding peaks and their widths during the calibration period are also of interest. When examining the bottom region 12, the decay time 16 can be examined again, but the height of the ground reflection 19 can also be examined. Depending on the value of the feature, a nonlinear weighting 24 of the sampling points 15 can be performed, and thus the sensitivity and robustness to the object can be significantly increased. An adaptive weighting 24 of the sample values ​​15 is advantageous when evaluating the corresponding measurement signal used for bottom monitoring so that reliable object detection is entirely possible. The challenge presented in object detection is the different distances between the object and the ground 11, and the different reflective behaviors of the object. By using adaptive weighting of 24, these effects can be handled better, resulting in a significant improvement in object detection.

[0056] Figure 4A set of curves for reference measurement curve 13 is specifically shown. Furthermore, a weighting 24 is applied to the sampled values ​​15. This weighting 24 is determined as a function of the curves in the corresponding set. It is clearly shown that measurement region 18 is most critical for object detection in the bottom region 12, and it lies precisely between the decay time 16 and the ground reflection 19. Furthermore, it can be set here that the weight of decay time 16 is significantly lower than that of ground reflection 19, which, at least in some cases, is input into the evaluation with even higher weights. In particular, the weighting 24 in measurement region 18 is therefore significantly higher than the weighting in decay time 16 and ground reflection region 17.

[0057] Specifically, weighting 24 can be provided to match the corresponding conditions during the generation of the reference measurement curve 13, and thus represent an accurate matching function for the corresponding environmental scene. Through adaptive weighting 24, object recognition can be improved overall by allowing the evaluation to match the conditions significantly better.

[0058] therefore, Figure 4 Specifically, a measurement region 18 is defined in the comparison measurement curve 14, wherein the weight 24 of the sample value 15 in the measurement region 18 is increased compared to the sample value 15 outside the measurement region 18. Specifically, the ground reflection region 17 and attenuation time 16 of the ultrasonic sensors 4, 5, 6, and 7 can be defined in the reference measurement curve 13, wherein the weight 24 of the sample value 15 in the ground reflection region 17 is increased compared to the sample value 15 within the attenuation time 16. To monitor the bottom region 12, specifically, as shown by weighting 24, a nonlinear weighting 24 can be applied to the attenuation time 16, the measurement region 18, and the ground reflection region 17.

[0059] The present invention also relates to a computer program product (not shown) and a computer-readable storage medium (not shown).

Claims

1. A method for operating an ultrasonic sensor device (2) for monitoring a bottom region (12) of a motor vehicle (1), wherein the monitoring is performed by means of the ultrasonic sensor device (2) of the motor vehicle (1), wherein an ultrasonic signal (U) is emitted into the bottom region (12) by means of at least one ultrasonic sensor (4, 5, 6, 7) of the ultrasonic sensor device (2), and a reflected ultrasonic signal (U) is received and evaluated by means of the at least one ultrasonic sensor (4, 5, 6, 7), wherein, After the motor vehicle (1) stops at the first time point (t1), a reference measurement curve (13) of the bottom region (12) is generated and stored based on at least one ultrasonic signal (U). Its features are, A measurement area (18) is determined in the reference measurement curve (13), and the monitoring process of the bottom area (12) is evaluated in the measurement area (18), wherein the measurement area (18) is determined based on the decay time (16) of the ultrasonic sensors (4, 5, 6, 7) and the ground reflection (19) on the ground (11). Wherein, after the motor vehicle (1) is restarted, at a second time point (t2) later than the first time point (t1), a comparison measurement curve (14) is generated based on at least one additional ultrasonic signal (U), and the reference measurement curve (13) is compared with the comparison measurement curve (14) in the measurement area (18), and based on the comparison, monitoring of the bottom area (12) is performed by means of the electronic computing device (3) of the ultrasonic sensor device. Furthermore, based on the comparison, the height change (∆h) between the bottom (10) of the motor vehicle (1) and the ground (11) in the bottom region (12) is determined, and the height change (∆h) is taken into account in the evaluation and monitoring, wherein the height change (∆h) between the first time point (t1) and the second time point (t2) is determined.

2. The method according to claim 1, Its features are, In the ultrasonic signal (U) of the reflected measurement curve (13), the ground reflection (19) of the ground (11) is determined, and the first height (h1) relative to the ground (11) is determined based on the determined ground reflection (19) at the first time point (t1). In the ultrasonic signal (U) of the other reflected measurement curve (14), the ground reflection (19) of the ground (11) is determined, and the second height (h2) relative to the ground (11) is determined based on the determined ground reflection (19) at the second time point (t2). The height change (∆h) is determined by comparing the first height (h1) and the second height (h2).

3. The method according to claim 1 or 2, Its features are, When determining the height change (∆h), the decay time (16) of the ultrasonic sensors (4, 5, 6, 7) is taken into account.

4. The method according to claim 1 or 2, Its features are, At least one first environmental condition is detected when the reference measurement curve (13) is generated, and at least one second environmental condition is detected when the comparison measurement curve (14) is generated, and the first environmental condition and the second environmental condition are taken into account when the height change (∆h) is determined.

5. The method according to any one of the preceding claims, Its features are, The ultrasonic signal (U) is emitted by at least one ultrasonic sensor (4, 5, 6, 7) in the area behind the wheels (8, 9) of the motor vehicle (1).

6. The method according to any one of the preceding claims, Its features are, The ultrasonic sensor device (2) has multiple ultrasonic sensors (4, 5, 6, 7) on the motor vehicle (1), wherein the bottom region (12) of the motor vehicle (1) is monitored by means of the multiple ultrasonic sensors (4, 5, 6, 7).

7. The method according to claim 6, Its features are, The corresponding reference measurement curve (13) and / or the corresponding comparison measurement curve (14) of one of the plurality of ultrasonic sensors (4, 5, 6, 7) is compared and verified with at least one corresponding reference measurement curve (13) and / or the corresponding comparison measurement curve (14) of another ultrasonic sensor (4, 5, 6, 7).

8. The method according to any one of the preceding claims, Its features are, During monitoring, objects in the measurement area that have been traversed during the generation of the reference measurement curve (13) are considered.

9. The method according to any one of the preceding claims, Its features are, The weighting (24) of the sample values ​​(15) in the measurement area (18) is increased compared to the samples (15) outside the measurement area (18).

10. The method according to any one of the preceding claims, Its features are, The ground reflection region (17) and decay time (16) of the ultrasonic sensors (4, 5, 6, 7) are determined in the reference measurement curve (13), wherein the weight (24) of the sample value (15) in the ground reflection region (17) is increased compared with the sample value (15) in the decay time (16).

11. The method according to claim 9, Its features are, The ground reflection region (17) and decay time (16) of the ultrasonic sensors (4, 5, 6, 7) are determined in the reference measurement curve (13), wherein the weighted (24) of the sample values ​​(15) in the ground reflection region (17) is increased compared to the sample values ​​(15) within the decay time (16). In order to monitor the bottom region (12), nonlinear weighting (24) is performed on the decay time (16), the measurement region (18) and the ground reflection region (17).

12. A computer program product having program code means, the program code means being stored in a computer-readable storage medium so that, when the computer program product is executed on a processor of an electronic computing device (3), it performs the method according to any one of claims 1 to 11.

13. A computer-readable storage medium having a computer program product according to claim 12.

14. An ultrasonic sensor device (2) for monitoring the bottom region (12) of a motor vehicle (1), having at least one first ultrasonic sensor (4, 5, 6, 7) and an electronic computing device (3), said ultrasonic sensor device (2) being designed to perform the method according to any one of claims 1 to 11.

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