CHECKING THE POSITIONING OF AN ULTRASONIC SENSOR ON A VEHICLE

Description

[0001] The present invention relates to a method for checking a positioning of an ultrasonic sensor on a vehicle, wherein the ultrasonic sensor is mounted in a holder on the vehicle.

[0002] The present invention also relates to a sensor arrangement comprising at least one ultrasonic sensor and a control unit which is connected to the at least one ultrasonic sensor via a data connection, wherein the at least one ultrasonic sensor is mounted in a holder on the vehicle, wherein the sensor arrangement is designed to carry out the above method for checking a positioning of an ultrasonic sensor on a vehicle.

[0003] The use of ultrasonic sensors for driving assistance systems is widespread in modern vehicles. For example, ultrasonic sensors are arranged on a front and / or rear bumper of the vehicle to monitor the vehicle's surroundings. Ultrasonic sensors are also used in the side areas of the vehicle. Sensor information from the sensors can be used, for example, in a near-field monitoring system, particularly a parking assistance system or a blind spot monitoring system.

[0004] In the current state of the art, such ultrasonic sensors are typically mounted using brackets that are located or to be located on the vehicle. Snap-in mounting of the ultrasonic sensors in the brackets is common due to the simple and quick installation.

[0005] As a result, there is a risk, both during production and during repairs in a car repair shop, that the ultrasonic sensors may not engage properly with the locking structures during installation and thus not be correctly positioned in the mount and thus on the vehicle. Accordingly, the longitudinal axes of the ultrasonic sensor and the associated mount differ. There is no guarantee that the ultrasonic sensors are in their intended installation position, for example, if their elevation angles and / or azimuth angles are incorrect. Furthermore, deviations from the intended installation position can also occur due to collisions or deliberate damage.

[0006] This can result in the detection zone of an incorrectly mounted ultrasonic sensor being misaligned. Additionally, malfunctions can occur if the ultrasonic sensor's membrane is restricted in its mobility, for example, if it is resting against a membrane frame on the mount.

[0007] Incorrectly installed ultrasonic sensors can impair or render inoperative other safety-relevant functions, such as pedestrian detection or autonomous or semi-autonomous maneuvering, in addition to the aforementioned parking assistance system or blind spot monitoring system. A particular disadvantage is that neither the ultrasonic sensor itself nor any support system to which this ultrasonic sensor belongs can detect and / or report incorrectly installed ultrasonic sensors. On the contrary, the ultrasonic sensor itself, as well as the driver assistance system to which this ultrasonic sensor belongs, will assume that the sensor is operating as intended.

[0008] In this context, DE 10 2010 024 205 A1 discloses an ultrasonic sensor, particularly for a vehicle, comprising a pot-shaped housing and a cover covering the rear of the housing. The cover can be designed, for example, as a film.

[0009] From DE 10 2013 022 061 A1 a method for producing an ultrasonic sensor for a motor vehicle is known, in which a membrane for emitting ultrasonic signals in a transmission direction and a sensor housing are provided for the ultrasonic sensor, in and / or to which the membrane is fastened.The sensor housing has a front side facing in the transmission direction of the membrane and a rear side facing in a rearward direction opposite to the transmission direction, and wherein the sensor housing is formed with a front opening for the membrane on the front side, wherein the front side of the sensor housing is connected to a cap formed from a film, with which the front opening of the sensor housing is covered in the transmission direction, wherein the membrane is introduced at least partially into a receptacle of the cap and a front side of the membrane facing in the transmission direction is connected to a base of the receptacle of the cap.

[0010] Furthermore, DE 10 2013 213 476 A1 discloses an ultrasonic sensor, in particular for a vehicle, as well as a method for producing an ultrasonic sensor and a motor vehicle with an ultrasonic sensor. The ultrasonic sensor comprises a transducer element arranged in a housing part and a cover part, wherein an electronic circuit is arranged on the cover part and the housing part is or can be connected to the cover part.

[0011] From DE 10 2018 205 048 A1 a method for monitoring the function of ultrasonic sensors is known, whereby a current amplitude of a ground echo is compared with an expected amplitude.

[0012] From DE 10 2011 120 535 A1 a method for adjusting at least a first sensor of a vehicle is known, wherein the measurement results of two sensors are compared.

[0013] From DE 10 2016 105 153 A1 a method for determining air humidity is known in which ultrasonic signals are emitted at two different frequencies and the echo amplitudes are evaluated.

[0014] Based on the above-mentioned prior art, the invention is therefore based on the object of specifying a method for checking a positioning of an ultrasonic sensor on a vehicle, wherein the ultrasonic sensor is mounted in a holder on the vehicle, as well as a sensor arrangement with at least one ultrasonic sensor and a control unit which is connected to the at least one ultrasonic sensor via a data connection, which enable a detection of an incorrect positioning of ultrasonic sensors.

[0015] The object is achieved according to the invention by the features of the independent claims. Advantageous embodiments of the invention are specified in the subclaims.

[0016] According to the invention, a method is thus provided for checking the positioning of an ultrasonic sensor on a vehicle, wherein the ultrasonic sensor is mounted in a holder on the vehicle, comprising the steps of locating a reference object in the detection range of the ultrasonic sensor, emitting at least one first ultrasonic pulse with the ultrasonic sensor at a first ultrasonic frequency, receiving at least one first echo signal with the ultrasonic sensor at the first ultrasonic frequency, emitting at least one second ultrasonic pulse with the ultrasonic sensor at a second ultrasonic frequency, receiving at least one second echo signal with the ultrasonic sensor at the second ultrasonic frequency, determining a ratio of echo amplitudes of the reference object in the at least one first and second echo signal, and outputting an erroneous positioning of the ultrasonic sensor,if the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal deviates by at least a predetermined limit value from a ratio for correct positioning of the ultrasonic sensor.

[0017] According to the invention, a sensor arrangement is also specified with at least one ultrasonic sensor and a control unit which is connected to the at least one ultrasonic sensor via a data connection, wherein the at least one ultrasonic sensor is mounted in a holder on the vehicle, wherein the sensor arrangement is designed to carry out the above method for checking a positioning of an ultrasonic sensor on a vehicle.

[0018] The basic idea of the present invention is therefore to exploit a determined frequency dependence of the detection range of the ultrasonic sensors to verify the positioning of the ultrasonic sensor by emitting ultrasonic signals and receiving corresponding echo signals at different frequencies using the ultrasonic sensor itself. The detection range defines an area that is, on the one hand, detected by ultrasonic signals emitted by the ultrasonic sensor, and from which, on the other hand, echo signals containing echoes from objects based on the emitted ultrasonic signals can be received. Thus, the ultrasonic sensor typically has a club-shaped detection range that usually extends symmetrically around a sensor axis.The sensor axis defines a central region of the ultrasonic sensor, which coincides with a central axis of the holder when the ultrasonic sensor is correctly positioned and / or mounted. At high frequencies, the detection range is narrower than at low frequencies. Furthermore, the amplitudes of echoes from objects located in the detection range are attenuated at low frequencies when the ultrasonic sensor is incorrectly positioned compared to correctly positioned. These effects can be exploited to determine correct or incorrect positioning of the ultrasonic sensor based on a ratio of the echo amplitudes of the reference object in the first and second echo signals. When the ultrasonic sensor is correctly positioned, the echo amplitudes of the reference object in the first and second echo signals are essentially the same due to appropriate calibration.However, a deviation occurs if the ultrasonic sensor is incorrectly positioned in the mount. Corresponding differences in amplitude can be detected for any position of the reference object within the detection range of the ultrasonic sensor.

[0019] The differences in the detection range between incorrect and correct positioning of the ultrasonic sensor are based on two effects. First, the sensor axis is tilted from its target position, which usually corresponds to the center axis of the mount, so that the detection range is also tilted. The detection range of the ultrasonic sensor is therefore incorrectly aligned. In addition, interference occurs if the mobility of an ultrasonic membrane of an incorrectly positioned ultrasonic sensor is restricted, for example by coming into contact with a membrane frame of the mount. This is often the case with incorrect positioning of the ultrasonic sensor because the ultrasonic sensor is not correctly mounted in the mount. This can further change the shape and alignment of the detection range.These disturbances, in particular, depend to a large extent on the relationship between geometric dimensions and the ultrasonic frequency of the ultrasonic sensor. Especially at the edge of the detection range, the frequency has a strong influence on sensitivity. If the ultrasonic sensor is incorrectly positioned, the echo amplitudes of the reference object in the echo signals differ particularly significantly at the two frequencies.

[0020] The detection range here defines an area in which an echo from the reference object can be received. This means that the ultrasonic signals can be emitted into the detection range, as well as the reception of echo signals with echoes from the detection range. The detection range is always related to the ultrasonic sensor and has a different shape and orientation when the ultrasonic sensor is correctly positioned than when it is incorrectly positioned. The center axis of the holder usually defines a target position for the ultrasonic sensor, i.e., an alignment of the sensor axis on the center axis of the holder corresponds to a correct positioning of the ultrasonic sensor. In order to compare the echo amplitudes of the reference object for the first and second ultrasonic frequencies, both echo signals must detect the reference object, i.e., the reference object must be in the detection range for both ultrasonic frequencies.

[0021] The ultrasonic sensor's mount is typically permanently attached to the vehicle, for example, to the front or rear bumper or to a side of the vehicle. Because of its quick and easy installation, the ultrasonic sensor is often mounted and positioned in its mount using a snap-in mount. In principle, however, other methods of mounting the ultrasonic sensor in the mount are also possible.

[0022] The execution of the process is controlled by the control unit. The control unit can, in principle, be any data processing device. In the automotive sector, so-called embedded systems are often used. The term ECU (Electronic Control Unit) is used for such control units.

[0023] The ultrasonic sensor is connected to the control unit via a data link. The data link can comprise a bus, for example, a DSI3 bus, CAN bus, Flexray, or even a proprietary implementation. In principle, however, a direct connection between the control unit and the ultrasonic sensor is also possible.

[0024] The sensor arrangement can, in principle, comprise any number of ultrasonic sensors arranged at any position in corresponding mounts on the vehicle. A plurality of ultrasonic sensors is commonly located on the rear and / or front of the vehicle. Ultrasonic sensors are also increasingly being mounted on the sides of vehicles. Each of the ultrasonic sensors in the sensor arrangement can be individually controlled by the control unit to perform the specified method.

[0025] Localizing a reference object in the detection range of the ultrasonic sensor involves detecting a suitable reference object in the detection range. To avoid complex laboratory setups, any objects located within the detection range can in principle be regarded as reference objects. To ensure reliable performance of the method, the reference object is regarded as static, i.e., it does not move relative to the vehicle to which the ultrasonic sensor is attached. The method is therefore usually carried out when the vehicle is stationary. During repairs in a workshop, however, a reference object can also be specifically positioned in the detection range in order to carry out the method.

[0026] Based on this, the process can be initiated in the workshop, for example, by interacting with a user interface on the control unit. Alternatively, the process can be performed by the control unit at predefined, arbitrarily calculated, or randomly selected intervals to continuously ensure the correct functioning of each connected ultrasonic sensor and, through this, the functioning of higher-level driving assistance systems.

[0027] Localizing the object essentially involves detecting an object that is suitable as a reference object, i.e., the object must be within the detection range of the ultrasonic sensor. This is preferably based on the narrowest detection range of the ultrasonic sensor based on the ultrasonic frequencies used. Additionally, the position of the reference object can be determined, for example, as the angular position of the reference object relative to the center axis of the mount and / or as the distance to the ultrasonic sensor. Further details are provided below.

[0028] To carry out the method, the ultrasonic sensor is operated at two different ultrasonic frequencies, i.e., the first and second ultrasonic frequencies, so that one ultrasonic frequency must be lower than the other. At least one first ultrasonic pulse is emitted by the ultrasonic sensor at a first ultrasonic frequency, and the corresponding echo signal with the echo amplitude of the reference object is subsequently received. The same applies to the second ultrasonic frequency. Using the different ultrasonic frequencies results in the different echo amplitudes of the reference object in the first and second echo signals.

[0029] Each of the echo signals may contain additional echoes from the vicinity of the ultrasonic sensor, such as ground echoes. These echoes are not considered further here and often have echo amplitudes that are significantly lower than the echo amplitude of the reference object.

[0030] The ultrasonic sensor can emit individual ultrasonic pulses and receive the corresponding echo signals, or the ultrasonic sensor can emit pulse sequences of individual ultrasonic pulses and receive a corresponding echo signal.

[0031] The order in which the first and second ultrasonic pulses are emitted is, in principle, arbitrary and can, for example, be carried out in any order, even mixed, when emitting multiple independent ultrasonic pulses of the first and / or second ultrasonic frequencies. The ultrasonic sensor's frequency response is adjusted accordingly to emit the ultrasonic pulses via its ultrasonic membrane and couple in the corresponding echo signals.

[0032] Receiving the respective echo signal involves receiving raw sensor data, which is then made available in this form for further processing to determine the ratio of the echo amplitudes of the reference object. In principle, preprocessing of the raw sensor data is possible, for example, using a filter. Accordingly, the raw data is transmitted from the ultrasonic sensor to the control unit, where the subsequent steps of the process are carried out.

[0033] Determining a ratio of echo amplitudes of the reference object in the at least one first and second echo signal relates in particular to the echo amplitudes originating from the reference object. These echo amplitudes of the reference object can usually be identified as peaks in an amplitude curve over time of the respective received echo signal. The ratio is determined, for example, as the amplitude of the received echo signal at the lower ultrasonic frequency divided by the amplitude of the received echo signal at the higher ultrasonic frequency. In this case, incorrect positioning of the ultrasonic sensor is detected by the fact that the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal is lower by at least a predetermined limit value than when the ultrasonic sensor is correctly positioned.However, the ratio can also be determined in reverse, whereby the incorrect positioning of the ultrasonic sensor can be detected by the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal being higher by at least a predetermined limit value than when the ultrasonic sensor is correctly positioned.

[0034] The procedural steps are given here only as an example in a sequence. The steps can be performed in different sequences without resulting in fundamental changes to the process.

[0035] In an advantageous embodiment of the invention, locating a reference object in the detection range of the ultrasonic sensor comprises detecting a position of the reference object in the detection range of the ultrasonic sensor based on echo signals received by a plurality of ultrasonic sensors. The sensor arrangement accordingly comprises a plurality of ultrasonic sensors that have a partially overlapping detection range, so that the reference object can be detected by multiple ultrasonic sensors. The plurality of ultrasonic sensors may or may not include the ultrasonic sensor whose positioning is to be checked. Overall, different configurations are possible for detecting the position of the reference object in the detection range of the ultrasonic sensor with the plurality of ultrasonic sensors. For example, each of the ultrasonic sensors can independently emit ultrasonic signals and receive echo signals based on them.When an ultrasonic signal is transmitted from one of the ultrasonic sensors, several of the ultrasonic sensors can receive echo signals based on it, provided the ultrasonic sensors are synchronized. The echo signals can be processed as raw data. Alternatively, it may be sufficient to detect and process distance information relating to the reference object in the echo signal in order to detect the position of the reference object. Neighboring ultrasonic sensors are preferably used so that their detection ranges at least partially overlap and echoes of the reference object can be received by a plurality of ultrasonic sensors. Based on the received echo signals, known multilateration methods, in particular trilateration, can be used, for example, to detect the position of the reference object in the detection range of the ultrasonic sensor.Preferably, based on the received echo signals, it is determined whether the object is suitable as a reference object. For this purpose, a height estimate for the object can be performed in a conventional manner based on the received echo signals. The reference object is preferably located in the same height range as the ultrasonic sensor. Furthermore, based on the received echo signals, a detection of walls can be performed in a conventional manner, i.e., whether the object has a large width.

[0036] In an advantageous embodiment of the invention, the localization of a reference object in the detection range of the ultrasonic sensor comprises transmitting at least one focused ultrasonic pulse with the ultrasonic sensor having a narrow detection range and receiving at least one corresponding echo signal with the ultrasonic sensor, wherein the reference object is localized by finding an echo of the reference object contained in the at least one received echo signal in the detection range of the ultrasonic sensor. As already explained above, the detection range of the ultrasonic sensor depends on the frequency, wherein the detection range is narrower and thus focused at higher frequencies. This results in a directional characteristic of the ultrasonic sensor compared to lower frequencies. Therefore, if based on the focused ultrasonic signal, ieIf the ultrasonic signal has a high frequency with a narrow transmission lobe and a high directivity, a corresponding echo signal is received, and an echo of the object is found in it, the object has a suitable positioning as a reference object, which means that it must also be detectable in the wider detection range for lower frequencies. If the reference object is located in the narrow detection range, the method can continue. It is ensured that the reference object is located in a central area of the corresponding detection range, at least for ultrasonic pulses with a wider detection range. Due to the focusing of the ultrasonic signal, the reference object is preferably located at a distance from the ultrasonic sensor that means it can also be detected for less focused ultrasonic signals at lower frequencies.Preferably, the localization of a reference object is carried out based on the transmission of at least one first or second ultrasonic pulse with the ultrasonic sensor at the first or second ultrasonic frequency and the reception of the corresponding echo signal. Depending on which ultrasonic signal has the higher frequency, the transmission of this ultrasonic signal represents the transmission of the at least one focused ultrasonic pulse with a narrow detection range. Therefore, it is advantageous to first transmit the at least one ultrasonic signal with the higher frequency in order to localize the reference object, so that no additional ultrasonic pulses need to be transmitted for localization. This applies at least if the reference object is located within the narrow detection range.Emitting at least one focused ultrasonic pulse with the ultrasonic sensor having a narrow detection range can, for example, correspond to operating the ultrasonic sensor at a nominal frequency. Alternatively, the at least one focused ultrasonic pulse is emitted at a frequency above the nominal frequency. It is only important that at least one of the first and second ultrasonic frequencies is not higher than the frequency used to emit the at least one focused ultrasonic pulse. Preferably, the first and second ultrasonic frequencies are not higher than the frequency used to emit the at least one focused ultrasonic pulse if the at least one focused ultrasonic pulse is neither the at least one first nor the at least one second ultrasonic pulse.

[0037] In an advantageous embodiment of the invention, locating a reference object in the detection range of the ultrasonic sensor comprises detecting a position of the reference object in the detection range of the ultrasonic sensor based on environmental detection with at least one environmental sensor consisting of an optical camera, a LiDAR-based environmental sensor, and a radar sensor. Thus, sensor information from additional environmental sensors located on the vehicle is used to detect the position of the reference object. The above statements regarding determining the position of the reference object apply accordingly.

[0038] In an advantageous embodiment of the invention, the method comprises an additional step for positioning the reference object in a central region of the detection range of the ultrasonic sensor, preferably in an angular range of + / - 15°, more preferably in an angular range of + / - 10°, and particularly preferably in an angular range of + / - 5°, in particular at an angle of approximately 0° relative to a central axis of the holder of the ultrasonic sensor. In the central region of the detection range, the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal is particularly meaningful. In addition, it is prevented that the reference object is located at the edge of the detection range and possibly not detected by the first or second ultrasonic signal. The central region is defined by the sensor axis of the ultrasonic sensor or the central axis of the holder.The angular range relates to an orientation in a horizontal plane. Positioning the reference object in a central region of the detection range of the ultrasonic sensor can include excluding objects located outside the central region. Advantageously, however, positioning is carried out in such a way that an instruction to move the vehicle and / or the reference object is issued in order to position the reference object accordingly. The positioning of the reference object is therefore preferably carried out in conjunction with locating the reference object in the detection range of the ultrasonic sensor. Accordingly, the positioning can be repeated as necessary until the reference object is positioned in the central region. Particularly preferably, the vehicle autonomously carries out positioning relative to the reference object in order to position the reference object in the central region.

[0039] In an advantageous embodiment of the invention, at least one of the first ultrasonic frequency and the second ultrasonic frequency lies in a frequency range below a nominal frequency of the ultrasonic sensor, and the corresponding other ultrasonic frequency lies above the first ultrasonic frequency, in particular above the nominal frequency. A frequency difference between the first and second ultrasonic frequencies is particularly relevant. In the case of conventional ultrasonic sensors, however, it has proven advantageous if the first or the second ultrasonic frequency is lower than the nominal frequency of the ultrasonic sensor. Further advantageously, the other ultrasonic frequency is higher than the nominal frequency of the ultrasonic sensor. Particularly preferably, the first and the second ultrasonic frequencies are evenly spaced from the nominal frequency. For example, the use of approximately 46 kHz and 59 kHz as the first and second ultrasonic frequencies, respectively, has proven to be advantageous.A second ultrasonic frequency has proven advantageous. Using approximately 49 kHz and 55 kHz as the first and second ultrasonic frequencies, respectively, has also proven effective. The same applies to frequencies between the specified values. Using approximately 49 kHz and 55 kHz as the first and second ultrasonic frequencies is possible with common ultrasonic sensors in a standard operating mode of a typical ultrasonic sensor and is therefore particularly easy to implement. A typical nominal frequency of an ultrasonic sensor is in the range between 49 kHz and 55 kHz, in particular around 52 kHz.

[0040] In an advantageous embodiment of the invention, the method comprises repeatedly transmitting the at least one first ultrasonic pulse and / or the at least one second ultrasonic pulse and repeatedly receiving the at least one first echo signal and / or the at least one second echo signal, and determining a ratio of echo amplitudes of the reference object in the at least one first and second echo signal comprises determining the ratio of the echo amplitudes of the reference object based on a plurality of first and second echo signals. Statistical methods can thus be applied to determine the echo amplitudes of the reference object in the at least one first and second echo signal and / or the ratio of the echo amplitudes of the reference object based on a plurality of first and second echo signals.Accordingly, echo amplitudes of the reference object in the at least one first and second echo signal and / or the ratio of the echo amplitudes can be determined, for example, as mean values, as weighted mean values and / or as a median. Thus, the echo amplitudes of the reference object in the at least one first and second echo signal can first be determined as indicated, so that the ratio of the amplitudes of the first and second echo signals can be formed based thereon. Alternatively, an individual ratio can first be determined for any combination of first and second echo signals, with the ratio then being determined based on the individual ratios. By using a plurality of echo signals, a higher degree of certainty can be achieved for the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal and thus for the correct positioning of the ultrasonic sensor.By increasing the accuracy of the echo amplitude ratio, false detection of incorrect ultrasonic sensor positioning can be reliably avoided. The threshold value can also be selected very closely to the ratio for correct ultrasonic sensor positioning.

[0041] In an advantageous embodiment of the invention, the method comprises a step for determining a position of the reference object in the detection range of the ultrasonic sensor, and the outputting of an incorrect positioning of the ultrasonic sensor comprises the outputting of an incorrect positioning of the ultrasonic sensor if the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal deviates by at least a predetermined limit value from the ratio for a correct positioning of the ultrasonic sensor, which is dependent on the position of the reference object in the detection range of the ultrasonic sensor.

[0042] In an advantageous embodiment of the invention, the method comprises a step for determining a position of the reference object in the detection range of the ultrasonic sensor, and the outputting of an incorrect positioning of the ultrasonic sensor comprises the outputting of an incorrect positioning of the ultrasonic sensor if the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal deviates from the ratio for a correct positioning of the ultrasonic sensor by at least one predetermined limit value, which is dependent on the position of the reference object in the detection range of the ultrasonic sensor.

[0043] The two aforementioned cases involve a position-dependent evaluation of the echo amplitudes of the reference object in the received echo signals. Thus, even with correct positioning of the ultrasonic sensor, the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal can depend on the positioning of the reference object. While for a narrow angular range around the sensor axis, the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal is approximately one, deviations can occur at different positions.To ensure the positioning of the ultrasonic sensor is particularly reliable, the position of the reference object is taken into account, either by making the ratio for correct positioning dependent on the position of the reference object, or by making the limit value dependent on the position of the reference object. The position of the reference object is, in particular, an angular position in the horizontal plane. When combining both the ratio for correct positioning and the limit value dependent on the position of the reference object, only one position of the reference object needs to be determined.

[0044] The invention will be explained in more detail below with reference to preferred embodiments and the accompanying drawings. The features presented may represent an aspect of the invention both individually and in combination. Features of various embodiments are transferable from one embodiment to another.

[0045] It shows Fig. 1 is a schematic view of an ultrasonic sensor according to a first preferred embodiment in a holder, wherein the ultrasonic sensor is correctly positioned and locked in the holder, Fig. 2 is a schematic view of the ultrasonic sensor in the holder according to the illustration in Fig. 1 , wherein the ultrasonic sensor is incorrectly positioned in the holder and accordingly not fully locked therein, Fig. 3 a diagram of the detection ranges of the ultrasonic sensor, which is in accordance with Fig. 1correctly positioned and locked in the holder, and the ultrasonic sensor, which is in accordance with Fig. 2 incorrectly positioned in the holder and accordingly not fully engaged in it, at a medium ultrasonic frequency, Fig. 4 a diagram of the detection ranges of the ultrasonic sensor, which is in accordance with Fig. 1 correctly positioned and locked in the holder, and the ultrasonic sensor, which is in accordance with Fig. 2 incorrectly positioned in the holder and accordingly not fully locked into it, at a high, first ultrasonic frequency, Fig. 5 a diagram of the detection ranges of the ultrasonic sensor, which is in accordance with Fig. 1 correctly positioned and locked in the holder, and the ultrasonic sensor, which is in accordance with Fig. 2incorrectly positioned in the holder and accordingly not fully locked therein, at a low, second ultrasonic frequency, Fig. 6 a diagram of ratios of echo amplitudes of a reference object in a first and second echo signal with the first and second ultrasonic frequency for the ultrasonic sensor which is in accordance with Fig. 1 correctly positioned and locked in the holder, and for the ultrasonic sensor, which is in accordance with Fig. 2 incorrectly positioned in the holder and accordingly not fully locked in it, via an angular position of the reference object, Fig. 7 a flow chart of a first method for checking a positioning of the ultrasonic sensor from the Figures 1 and 2 on a vehicle, wherein the ultrasonic sensor is mounted in a holder on the vehicle, Fig. 8 a flowchart of a second method for checking a positioning of the ultrasonic sensor from the Figs. 1 and 2on a vehicle, wherein the ultrasonic sensor is mounted in a holder on the vehicle, and Fig. 9 is a schematic representation of a vehicle with a sensor arrangement with a plurality of ultrasonic sensors from Figs. 1 and 2 and a control unit connected to the plurality of ultrasonic sensors.

[0046] The Figure 1 shows an ultrasonic sensor 10 according to a first preferred embodiment.

[0047] The ultrasonic sensor 10 comprises a sensor housing 12 on which two locking projections 14 are formed diametrically opposite each other. The ultrasonic sensor 10 further comprises a Figure 1 invisible sensor head with an ultrasonic membrane. Control and evaluation electronics are arranged within the sensor housing 12. The sensor housing 12 is closed with a cover 16. From a Figure 1A connector socket 18 protrudes radially from the proximal end of the sensor housing 12. It is understood that in other embodiments, the connector socket 18 may also protrude at other angles from the proximal end of the sensor housing.

[0048] The ultrasonic sensor 10 is accommodated in a holder 20. The holder 20 comprises two locking arms 22 with locking openings (not shown here). The locking arms 22 can be resilient in the radial direction and serve to hold and secure the ultrasonic sensor 10. When the ultrasonic sensor 10 is properly positioned in the holder 20, both locking projections 14 engage the corresponding openings of the locking arms 22, and the ultrasonic sensor 10 is both correctly positioned and securely held in the sensor holder 20.

[0049] The ultrasonic sensor 10 is part of a sensor arrangement 30 comprising a plurality of ultrasonic sensors 10 and a control unit 32 connected to the ultrasonic sensors 10 via a data connection 34. The control unit 32 can, in principle, be any data processing device. In the automotive sector, so-called embedded systems are often used for this purpose. The term ECU (Electronic Control Unit) is used for such control units 32. The data connection 34 can comprise a bus, for example, a DSI3 bus, CAN bus, Flexray, or even a proprietary implementation. In principle, however, a direct data connection 34 between the control unit 32 and each of the ultrasonic sensors 10 is also possible.

[0050] The ultrasonic sensors 10 of the sensor arrangement 30 are mounted in this embodiment on a rear side and a front side of a vehicle 36, as shown in Figure 9For this purpose, the holders 20 of the ultrasonic sensors 10 are fixedly mounted on the rear and front of the vehicle 36, for example on a front or rear bumper of the vehicle 36.

[0051] Also Figure 2 shows the ultrasonic sensor 10 from Figure 1 the first preferred embodiment.

[0052] In contrast to the representation in Figure 1However, only one of the two locking projections 14 of the ultrasonic sensor 10 engages in the corresponding opening of one of the locking arms 22. As a result, the ultrasonic sensor 10 is not positioned correctly. The consequence of this is that the ultrasonic sensor 10, although supposedly securely fastened in the holder 20, is in reality tilted and thus not positioned correctly in the holder 20. Such improper positioning of the ultrasonic sensor 10 in the holder 20 results in positional and / or angular deviations of a sensor axis relative to a central axis 42 of the holder 20, which can lead to incorrect functioning of the ultrasonic sensor 10 and, furthermore, to malfunctions of driving assistance systems that use this ultrasonic sensor 10.

[0053] In order to detect such incorrect positioning, a Figure 7The first method shown for checking the positioning of the ultrasonic sensor 10 in the holder 20 on the vehicle 36 is described. The execution of the method is controlled by the control unit 32. The control unit 32 can individually control each of the ultrasonic sensors 10 of the sensor arrangement 30 via the data connection 34 in order to carry out the method described below. The method is described with additional reference to the Figures 3 to 6 described.

[0054] The method begins with step S100, which relates to locating a reference object in the detection range 40 of the ultrasonic sensor 10. The detection range 40 here defines an area in which an echo of the reference object can be received for a first and a second ultrasonic frequency. The detection range 40 is defined with respect to a correct positioning of the ultrasonic sensor 10 with its sensor axis in accordance with a center axis 42 of the holder 20, which also defines a correct positioning of the ultrasonic sensor 10. For a nominal frequency, ie in a medium frequency range, Figure 3 Detection areas 40a, 40b corresponding to a correct positioning of the ultrasonic sensor 10 in the holder 20, as in Figure 1 shown, and for incorrect positioning of the ultrasonic sensor 10 in the holder 20, as shown in Figure 2 represented, shown.

[0055] Locating a reference object in the detection range 40 of the ultrasonic sensor 10 involves detecting a suitable reference object in the detection range 40. The object must therefore be suitable as a reference object and be located in the detection range 40 of the ultrasonic sensor 10.

[0056] For this purpose, a position of the reference object in the detection range 40 of the ultrasonic sensor 10 is determined based on echo signals received by a plurality of ultrasonic sensors 10. For example, all ultrasonic sensors 10 located at the front of the vehicle 36 independently emit ultrasonic signals and receive echo signals based thereon in order to carry out the method for an ultrasonic sensor 10 at the front of the vehicle 36. Distance information relating to the reference object is acquired from the echo signals in the echo signal and processed in order to acquire the position of the reference object. For example, known multilateration methods, in particular trilateration, are used to acquire the position of the reference object in the detection range 40 of the ultrasonic sensor 10. In addition, based on the received echo signals, it is determined whether the object is suitable as a reference object.For this purpose, a height estimate for the object is performed in a conventional manner based on the received echo signals. The reference object is preferably located in a height range similar to the ultrasonic sensor 10. Furthermore, based on the received echo signals, a detection of walls, for example, is performed in a conventional manner to exclude such objects. The position of the reference object is determined relative to the ultrasonic sensor 10 as an angle in a horizontal plane, along with a distance.

[0057] Step S110 relates to positioning the reference object in a central region of the detection range 40 of the ultrasonic sensor 10, preferably in an angular range of + / - 15°, more preferably in an angular range of + / - 10°, and particularly preferably in an angular range of + / - 5°, in particular at an angle of approximately 0° relative to a central axis 42 of the holder 20, which corresponds to a sensor axis of the ultrasonic sensor 10 when the ultrasonic sensor 10 is correctly positioned.

[0058] Based on the position of the reference object determined in step S100, an instruction is issued to move the vehicle 36 and / or the reference object in order to position the reference object accordingly relative to the vehicle 36 and thus relative to the ultrasonic sensor 10. The positioning of the reference object therefore occurs in conjunction with the localization of the reference object in the detection range 40 of the ultrasonic sensor 10. Accordingly, the positioning is checked again in a further step S100, and if necessary, the positioning of the reference object is also carried out again until the reference object has a desired position in the central region of the detection range 40. Preferably, the vehicle 36 autonomously performs the positioning relative to the reference object in order to position the reference object in the central region of the detection range 40.

[0059] Step S120 involves transmitting a first ultrasonic pulse with the ultrasonic sensor 10 at a first ultrasonic frequency. The first ultrasonic frequency here is approximately 59 kHz. The ultrasonic sensor 10 has, for example, a nominal frequency of 52 kHz, so that the first ultrasonic frequency is above the nominal frequency.

[0060] Step S130 involves receiving a first echo signal with the ultrasonic sensor 10 at the first ultrasonic frequency. Detection areas 40a, 40b are correspondingly suitable for correct positioning of the ultrasonic sensor 10 in the holder 20, as shown in Figure 1 shown, and for incorrect positioning of the ultrasonic sensor 10 in the holder 20, as shown in Figure 2 shown are in Figure 4 shown. Raw sensor data is received as the first echo signal. The raw sensor data is transmitted from the ultrasonic sensor 10 to the control unit 32.

[0061] Step S140 involves transmitting a second ultrasonic pulse with the ultrasonic sensor 10 at a second ultrasonic frequency. The second ultrasonic frequency here is approximately 46 kHz and is thus below the nominal frequency.

[0062] Step S150 involves receiving a second echo signal with the ultrasonic sensor 10 at the second ultrasonic frequency. Detection areas 40a, 40b are correspondingly suitable for correct positioning of the ultrasonic sensor 10 in the holder 20, as shown in Figure 1 shown, and for incorrect positioning of the ultrasonic sensor 10 in the holder 20, as shown in Figure 2 shown are in Figure 5 shown. Raw sensor data is also received as a second echo signal, which is transmitted from the ultrasonic sensor 10 to the control unit 32.

[0063] Step S160 involves determining a ratio of echo amplitudes of the reference object in the first and second echo signals. Corresponding ratios 44 are shown in Figure 6 shown, wherein a ratio 44a for a correct positioning of the ultrasonic sensor 10 in the holder 20, as in Figure 1 shown, and a ratio 44b for an incorrect positioning of the ultrasonic sensor 10 in the holder 20, as in Figure 2 shown, are specified.

[0064] The levels of echo amplitudes of the reference object in the first and second echo signals are appropriately detected and processed. Processing takes place in control unit 32.

[0065] Step S170 involves outputting an incorrect positioning of the ultrasonic sensor 10 if the ratio 44 of the echo amplitudes of the reference object in the first and second echo signals deviates by at least a predetermined limit value from a ratio for a correct positioning of the ultrasonic sensor 10. The output is performed by the control unit 32.

[0066] In this case, an incorrect positioning of the ultrasonic sensor 10 is output when the ratio 44 of the echo amplitudes of the reference object in the first and second echo signals deviates from the ratio for a correct positioning of the ultrasonic sensor 10 by at least a predetermined limit value, which is dependent on the position of the reference object in the detection range 40 of the ultrasonic sensor 10. As in Figure 6As shown, the curves of the ratios of the echo amplitudes vary depending on the position of the reference object in the detection area 40, which was determined in step S100. Thus, a position-dependent evaluation of the ratio of the echo amplitudes of the reference object in the received echo signals is carried out.

[0067] Below is a Figure 8The second method shown for checking the positioning of the ultrasonic sensor 10 in the holder 20 on the vehicle 36 is described. The method is also carried out using the sensor arrangement 30 described above. The execution of the method is controlled by the control unit 32. The control unit 32 can individually control each of the ultrasonic sensors 10 of the sensor arrangement 30 via the data connection 34 in order to carry out the method described below. The second method partially corresponds to the first method, so that essentially the differences between the two methods are described here.

[0068] The second method begins with step S120, as previously described with reference to the first method, which involves transmitting a first ultrasonic pulse with the ultrasonic sensor 10 at a first ultrasonic frequency. The first ultrasonic frequency is also approximately 59 kHz here. The ultrasonic sensor 10 has, for example, a nominal frequency of 52 kHz, so that the first ultrasonic frequency is above the nominal frequency.

[0069] Step S130 involves receiving a first echo signal with the ultrasonic sensor 10 at the first ultrasonic frequency. Detection areas 40a, 40b are correspondingly suitable for correct positioning of the ultrasonic sensor 10 in the holder 20, as shown in Figure 1 shown, and for incorrect positioning of the ultrasonic sensor 10 in the holder 20, as shown in Figure 2 shown are in Figure 4shown. Raw sensor data is received as the first echo signal. The raw sensor data is transmitted from the ultrasonic sensor 10 to the control unit 32.

[0070] Step S135 relates to locating a reference object in the detection range 40 of the ultrasonic sensor 10. Here, the detection range 40 also defines an area in which an echo of the reference object can be received for a first and a second ultrasonic frequency. The detection range 40 is defined with respect to a correct positioning of the ultrasonic sensor 10 with its sensor axis aligned with a center axis of the mount 20, which defines the correct positioning of the ultrasonic sensor 10.

[0071] Localizing the reference object in the detection range 40 of the ultrasonic sensor 10 involves detecting a suitable reference object in the detection range 40.

[0072] Accordingly, the reference object is determined in the first received echo signal. The first received echo signal is based on the transmission of the first ultrasonic pulse at the high frequency of 59 kHz, which is why the first ultrasonic pulse is a focused ultrasonic pulse, resulting in a narrow detection range 40 for receiving the first echo signal with the ultrasonic sensor 10.

[0073] If the first echo signal contains an echo of the reference object, it is located within the detection range 40 of the ultrasonic sensor 10. The object has a suitable positioning as a reference object, which means it can also be located in the wider detection range 40 for lower frequencies.

[0074] Step S140 involves transmitting a second ultrasonic pulse with the ultrasonic sensor 10 at a second ultrasonic frequency. The second ultrasonic frequency here is approximately 46 kHz and is thus below the nominal frequency of the ultrasonic sensor 10.

[0075] Step S150 involves receiving a second echo signal with the ultrasonic sensor 10 at the second ultrasonic frequency. Detection areas 40a, 40b are correspondingly suitable for correct positioning of the ultrasonic sensor 10 in the holder 20, as shown in Figure 1 shown, and for incorrect positioning of the ultrasonic sensor 10 in the holder 20, as shown in Figure 2 shown are in Figure 5 shown. Raw sensor data is also received as a second echo signal, which is transmitted from the ultrasonic sensor 10 to the control unit 32.

[0076] Step S160 involves determining a ratio of echo amplitudes of the reference object in the first and second echo signals. Corresponding ratios 44 are shown in Figure 6 shown, wherein a ratio 44a for a correct positioning of the ultrasonic sensor 10 in the holder 20, as in Figure 1 shown, and a ratio 44b for an incorrect positioning of the ultrasonic sensor 10 in the holder 20, as in Figure 2 shown, is specified.

[0077] The levels of echo amplitudes of the reference object in the first and second echo signals are detected and processed accordingly.

[0078] Step S170 involves outputting an incorrect positioning of the ultrasonic sensor 10 if the ratio 44 of the echo amplitudes of the reference object in the first and second echo signals deviates by at least a predetermined limit value from a ratio for a correct positioning of the ultrasonic sensor 10. In the second method, the limit value is independent of an exact position of the reference object, since, unlike in the first method, the exact position was not determined.

[0079] In the Figure 8 With the second method presented, it is possible to dispense with a dedicated detection mode if the ultrasonic sensors 10 transmit alternately at a high frequency and a low frequency during normal operation. This avoids dead times during normal operation. Furthermore, continuous monitoring is possible. List of reference symbols

[0080] 10Ultrasonic sensor 12Sensor housing 14Locking projection 16Cover 18Connector socket 20Bracket 22Locking arm 30Sensor arrangement 32Control unit 34Data connection 36Vehicle 40Detection range 40aDetection range correct positioning 40bDetection range incorrect positioning 42Center axis 44Echo amplitude ratio 44aEcho amplitude ratio correct positioning 44bEcho amplitude ratio incorrect positioning

Claims

1. Method for checking the positioning of an ultrasonic sensor (10) on a vehicle (36), wherein the ultrasonic sensor (10) is installed in a mounting bracket (20) on the vehicle (36), said method comprising the steps localizing a reference object in the detection region (40) of the ultrasonic sensor (10), emitting at least one first ultrasonic pulse with a first ultrasonic frequency by means of the ultrasonic sensor (10), receiving at least one first echo signal at the first ultrasonic frequency by means of the ultrasonic sensor (10), emitting at least one second ultrasonic pulse with a second ultrasonic frequency by means of the ultrasonic sensor (10), receiving at least one second echo signal at the second ultrasonic frequency by means of the ultrasonic sensor (10), ascertaining a ratio (44) of echo amplitudes of the reference object in the at least one first and second echo signal, and outputting an error in the positioning of the ultrasonic sensor (10) if the ratio (44) of the echo amplitudes of the reference object in the at least one first and second echo signal deviates from a ratio (44) for the correct positioning of the ultrasonic sensor (10) by at least one specified threshold value.

2. Method according to Claim 1, characterized in that the localizing of a reference object in the detection region (40) of the ultrasonic sensor (10) comprises detecting a position of the reference object in the detection region (40) of the ultrasonic sensor (10) based on echo signals received using a plurality of ultrasonic sensors (10).

3. Method according to Claim 1, characterized in that the localizing of a reference object in the detection region (40) of the ultrasonic sensor (10) comprises emitting at least one focused ultrasonic pulse by means of the ultrasonic sensor (10) having a narrow detection region (40) and receiving at least one corresponding echo signal by means of the ultrasonic sensor (10), wherein the reference object is localized by finding an echo of the reference object contained in the at least one received echo signal in the detection region (40) of the ultrasonic sensor (10).

4. Method according to Claim 1, characterized in that the localizing of a reference object in the detection region (40) of the ultrasonic sensor (10) comprises detecting a position of the reference object in the detection region (40) of the ultrasonic sensor (10) based on a detection of the surroundings using at least one environment sensor from an optical camera, a LiDAR-based environment sensor and a radar sensor.

5. Method according to one of the preceding claims, characterized in that the method comprises an additional step for positioning the reference object in a central region of the detection region (40) of the ultrasonic sensor (10).

6. Method according to one of the preceding claims, characterized in that the first ultrasonic frequency is in a frequency range below a nominal frequency of the ultrasonic sensor (10), and the second ultrasonic frequency is above the first ultrasonic frequency, or the second ultrasonic frequency is in a frequency range below a nominal frequency of the ultrasonic sensor (1), and the first ultrasonic frequency is above the second ultrasonic frequency.

7. Method according to one of Claims 1 to 5, characterized in that the first ultrasonic frequency is in a frequency range below a nominal frequency of the ultrasonic sensor (10), and the second ultrasonic frequency is above the nominal frequency, or the second ultrasonic frequency is in a frequency range below a nominal frequency of the ultrasonic sensor (1), and the first ultrasonic frequency is above the nominal frequency.

8. Method according to one of the preceding claims, characterized in that the method comprises repeatedly emitting the at least one first ultrasonic pulse and / or the at least one second ultrasonic pulse and repeatedly receiving the at least one first echo signal and / or the at least one second echo signal, and ascertaining a ratio (44) of echo amplitudes of the reference object in the at least one first and second echo signal comprises ascertaining the ratio (44) of the echo amplitudes of the reference object based on a plurality of first and second echo signals.

9. Method according to one of the preceding claims, characterized in that the method comprises a step for determining a position of the reference object in the detection region (40) of the ultrasonic sensor (10), and an error in the positioning of the ultrasonic sensor (10) is output if the ratio (44) of the echo amplitudes of the reference object in the at least one first and second echo signal deviates by at least one specified threshold value from the ratio (44) for the correct positioning of the ultrasonic sensor (10), which is dependent on the position of the reference object in the detection region (40) of the ultrasonic sensor (10).

10. Method according to one of the preceding claims, characterized in that the method comprises a step for determining a position of the reference object in the detection region of the ultrasonic sensor (10), and an error in the positioning of the ultrasonic sensor (10) is output if the ratio (44) of the echo amplitudes of the reference object in the at least one first and second echo signal deviates from the ratio (44) for the correct positioning of the ultrasonic sensor (10) by at least one specified threshold value, which is dependent on the position of the reference object in the detection region (40) of the ultrasonic sensor (10).

11. Sensor assembly (30) having at least one ultrasonic sensor (10) and a control unit (32), which is connected via a data link (34) to the at least one ultrasonic sensor (10), wherein the at least one ultrasonic sensor (10) is installed in a mounting bracket (20) on a vehicle (10), characterized in that the sensor assembly (30) is designed to carry out the method for checking the positioning of the ultrasonic sensor (10) on the vehicle (10) according to one of Claims 1 to 10.