Checking the installation of ultrasonic sensors on a vehicle

Abstract

The invention relates to a method for checking the positioning of an ultrasonic sensor (10) on a vehicle (36), the ultrasonic sensor (10) being mounted in a holder (20) on the vehicle (36). The method has the following steps: positioning a reference object in a detection region (40) of the ultrasonic sensor (10), emitting at least one first ultrasonic pulse having 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 having 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), determining a ratio (44) of the echo amplitudes of the reference object in the at least one first and second echo signal, and outputting a mispositioning 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) of a correct positioning of the ultrasonic sensor (10) by at least one specified threshold value. The invention also relates to a sensor assembly (30) comprising at least one ultrasonic sensor (10) and a control unit (32), which is connected to the at least one ultrasonic sensor (10) via a data connection (34), wherein the at least one ultrasonic sensor (10) is mounted in a holder (20) on the vehicle (10) and the sensor assembly (30) is designed to carry out the aforementioned method in order to check the positioning of the ultrasonic sensor (10) on the vehicle (10).

Description

TECHNICAL FIELD

[0001] The present application relates to a method for checking the installation of an ultrasonic sensor on a vehicle, wherein the ultrasonic sensor is mounted in a mounting bracket on the vehicle.

[0002] The present application also relates to a sensor assembly having at least one ultrasonic sensor and a control unit connected to the at least one ultrasonic sensor via a data connection, wherein the at least one ultrasonic sensor is mounted in a mounting bracket on the vehicle, wherein the sensor assembly is designed to carry out the above-mentioned method for checking the installation of an ultrasonic sensor on a vehicle. BACKGROUND

[0003] The use of ultrasonic sensors for vehicle driving assistance systems is a widespread feature of current vehicles. Ultrasonic sensors are arranged, for example, on the front and / or rear fenders of the vehicle for monitoring the environment of the vehicle. In addition, ultrasonic sensors are also used in the side area of the vehicle. The sensor information of the sensors can be used, for example, in near-field monitoring systems, in particular parking assistance systems or blind spot monitoring systems.

[0004] In the prior art, such ultrasonic sensors are usually fixed by means of a mounting bracket which is arranged or designed to be arranged on the vehicle. Due to the simple and quick installation, a snap-fit of the ultrasonic sensor in the bracket is often used.

[0005] During production and during repairs in the garage, there is therefore a risk that the ultrasonic sensor does not engage correctly with the latching structure during installation and is therefore not correctly installed in the mounting bracket and thus not correctly installed on the vehicle. The longitudinal axis of the ultrasonic sensor and the associated bracket will accordingly be different. For example, due to an incorrect elevation and / or azimuth angle of the ultrasonic sensor, it cannot be guaranteed that the ultrasonic sensor is located in its intended installation position. Due to a collision or deliberate damage, it can also deviate from the intended installation position.

[0006] On the one hand, this can result in the detection area of the incorrectly installed ultrasonic sensor being misaligned. In addition, a malfunction can occur on the ultrasonic sensor if the movement of the ultrasonic membrane of the incorrectly installed ultrasonic sensor is restricted, for example if it is in contact with the membrane holder of the mounting bracket.

[0007] Due to an incorrect installation of the ultrasonic sensor, other safety-relevant functions, such as pedestrian detection or autonomous or semi-autonomous maneuvering, are also affected or not functioning in addition to the above-mentioned parking assistance systems or blind spot monitoring systems. A particular disadvantage is that neither the ultrasonic sensor itself nor the assistance system to which the ultrasonic sensor belongs detects and / or signals an incorrectly installed ultrasonic sensor. Rather, the ultrasonic sensor itself and the driving assistance system to which the ultrasonic sensor belongs will assume a correct operation.

[0008] Against this background, DE 10 2010 024 205 A1 discloses an ultrasonic sensor, in particular for a vehicle, having a pot-shaped housing and a cover covering the housing at the rear. The cover can be designed as a foil, for example.

[0009] The document DE 10 2013 022 061 A1 discloses a method for producing an ultrasonic sensor for a motor vehicle, wherein the ultrasonic sensor is provided with a diaphragm for emitting ultrasonic signals in a transmission direction and a sensor housing, the diaphragm being fixed in and / or on the sensor housing. The sensor housing has a front side pointing in the direction of diaphragm emission and a rear side pointing in a rearward direction opposite the emission direction, and wherein the sensor housing is formed on the front side with a front-side opening for the diaphragm, wherein the front side of the sensor housing is connected to a cap made of a foil, the front-side opening of the sensor housing being covered by the cap in the emission direction, and wherein the diaphragm is at least partially inserted into a receptacle of the cap and thus the front side of the diaphragm pointing in the direction of diaphragm emission is connected to a base of the receptacle of the cap.

[0010] Furthermore, it is known from DE 10 2013 213 476 A1 an ultrasonic sensor, in particular for a vehicle, and a method for producing an ultrasonic sensor and a motor vehicle having 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 connected or connectable to the cover part. SUMMARY

[0011] Therefore, based on the above-mentioned prior art, it is the object of the present invention to specify a method for checking the installation of an ultrasonic sensor on a vehicle, wherein the ultrasonic sensor is mounted in a mounting bracket on the vehicle and the sensor assembly has at least one ultrasonic sensor and a control unit connected to the at least one ultrasonic sensor via a data connection, wherein the method and the assembly allow to detect an incorrect installation of the ultrasonic sensor.

[0012] According to the invention, this object is achieved by the features of the independent claims. Advantageous configurations of the invention are specified in the dependent claims.

[0013] According to the present application, therefore, a method for checking the installation of an ultrasonic sensor on a vehicle is specified, wherein the ultrasonic sensor is mounted in a mounting bracket on the vehicle, the method comprising the steps of positioning a reference object in a detection region of the ultrasonic sensor, emitting at least one first ultrasonic pulse having a first ultrasonic frequency by means of the ultrasonic sensor, receiving at least one first echo signal of the first ultrasonic frequency by means of the ultrasonic sensor, emitting at least one second ultrasonic pulse having a second ultrasonic frequency by means of the ultrasonic sensor, receiving at least one second echo signal of the second ultrasonic frequency by means of the ultrasonic sensor, determining a ratio of echo amplitudes of the reference object in the at least one first and second echo signal, and outputting an installation error of the ultrasonic sensor if the ratio of echo amplitudes of the reference object in the at least one first and second echo signal deviates from a ratio for a correct installation of the ultrasonic sensor by at least one specified threshold value.

[0014] The present application also relates to a sensor assembly having 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 mounting bracket on a vehicle, wherein the sensor assembly is designed to carry out the above-mentioned method for checking the installation of an ultrasonic sensor on a vehicle.

[0015] The basic idea of the present application is therefore to check the installation of an ultrasonic sensor by using the established frequency dependence of the detection region of the ultrasonic sensor, by using the ultrasonic sensor itself to emit ultrasonic signals and to receive corresponding echo signals having different frequencies. The detection region defines a region which is captured by the ultrasonic signals emitted by the ultrasonic sensor and from which echo signals having object echoes based on the emitted ultrasonic signals can be received. For example, an ultrasonic sensor usually has a petal-shaped detection region which usually extends symmetrically around a sensor axis. The sensor axis defines a central region of the ultrasonic sensor which corresponds to the central axis of the mounting bracket for a correct installation and / or correct installed state of the ultrasonic sensor. At high frequencies, the detection region is narrower than at low frequencies. Furthermore, the amplitude of the echo caused by an object in the detection region is attenuated at low frequencies compared to a correctly installed ultrasonic sensor using an incorrectly installed ultrasonic sensor. Based on the ratio of the echo amplitudes of the reference object in the first and second echo signals, these effects can be used to determine a correct or incorrect installation of the ultrasonic sensor. When the ultrasonic sensor is correctly installed, the echo amplitudes of the reference object in the first and second echo signals are essentially equal due to appropriate calibration. However, if the installation of the ultrasonic sensor in the mounting bracket is incorrect, a deviation occurs. For an arbitrary position of the reference object in the detection region of the ultrasonic sensor, a corresponding difference in the amplitudes can be detected.

[0016] The difference in the detection area between an incorrect and a correct setup of the ultrasonic sensor is based on two effects. First, the sensor axis is tilted away from its target position, which usually corresponds to the central axis of the mounting bracket, so that the detection area is tilted with respect to it as well. Thus, the detection area of the ultrasonic sensor is misaligned. In addition, a malfunction occurs if the movement of the ultrasonic membrane of the incorrectly setup ultrasonic sensor is restricted, for example, if it is in contact with the membrane holder of the mounting bracket. This often occurs when the ultrasonic sensor is not correctly held in the mounting bracket. This allows a further modification of the shape and orientation of the detection area. In particular, these perturbations strongly depend on the relation between the geometry of the ultrasonic sensor and the ultrasonic frequency. In particular, the frequency has a strong influence on the sensitivity in the peripheral region of the detection area. If the ultrasonic sensor is incorrectly setup, the echo amplitudes of the reference object in the echo signals will thus differ particularly significantly at the two frequencies.

[0017] Here, the detection area defines the region in which an echo of the reference object can be received. This means that an ultrasonic signal can be radiated into the detection area and an echo signal can be received with an echo from the detection area. The detection area is associated with each ultrasonic sensor and has a different shape and orientation when the ultrasonic sensor is correctly setup compared to when the sensor is incorrectly setup. The central axis of the mounting bracket usually defines the target position of the ultrasonic sensor, i.e. an alignment of the sensor axis with the central axis of the bracket corresponds to a correct setup of the ultrasonic sensor. In order to compare the echo amplitudes of the reference object at the first and second ultrasonic frequencies, both echo signals must detect the reference object, i.e. the reference object must be located within the detection area of both ultrasonic frequencies.

[0018] The ultrasonic sensor mounting bracket is usually fixed on the vehicle, for example on the front or rear fender of the vehicle or in the side area of the vehicle. The ultrasonic sensor is often installed in its mounting bracket and thus setup by snap-in mounting, as this provides a simple and quick installation. However, in principle, other methods of installing the ultrasonic sensor in the mounting bracket are also possible.

[0019] The method is executed under the control of a control unit. In principle, the control unit can be any desired 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.

[0020] The ultrasonic sensors are connected to the control unit via a data link. The data link can comprise a bus, for example in the form of a DSI3 bus, a CAN bus, FlexRay or as a proprietary implementation. However, in principle, a direct connection between the control unit and the ultrasonic sensors is also possible.

[0021] The sensor arrangement can comprise substantially any number of ultrasonic sensors which are arranged in arbitrary desired positions on the vehicle in corresponding mounting brackets. Thus, a plurality of ultrasonic sensors are distributed at the rear and / or at the front of the vehicle. Ultrasonic sensors are also increasingly being installed on the sides of the vehicle. Each ultrasonic sensor of the sensor assembly can then be individually controlled by the control unit in order to carry out the specified method.

[0022] Positioning a reference object in the detection region of the ultrasonic sensor comprises detecting a suitable reference object in the detection region. In order to avoid complex laboratory settings, in principle any object located in the detection region can be considered a reference object. In order to be able to reliably carry out the method, the reference object used to carry out the method is considered static, i.e. it does not move relative to the vehicle on which the ultrasonic sensor is mounted. The method is therefore typically carried out when the vehicle is stationary. However, during repair work in a workshop, the reference object can also be deliberately positioned in the detection region in order to implement the method.

[0023] On this basis, the method can be deliberately started in the workshop, for example by interaction via an operator interface of the control unit. Alternatively, the method can be carried out by the control unit at specified, arbitrarily calculated or even randomly selected intervals in order to ensure correct functioning of each connected ultrasonic sensor and, furthermore, to ensure continuous functioning of higher-level driver assistance systems.

[0024] The positioning of the object essentially involves detection of an object which is suitable as a reference object, i.e. the object must be in the detection region of the ultrasonic sensor. Preferably, the narrowest detection region of the ultrasonic sensor is assumed on the basis of the ultrasonic frequency used. Furthermore, the position of the reference object can be determined, for example as an angular position of the reference object relative to a central axis of the mounting bracket and / or as a distance to the ultrasonic sensor. Further details are given below.

[0025] In order to implement the method, the ultrasonic sensor is operated at two different ultrasonic frequencies, i.e. at a first and a second ultrasonic frequency, such that one ultrasonic frequency must be lower than the other. At least one first ultrasonic pulse having the first ultrasonic frequency is emitted using the ultrasonic sensor, and a corresponding echo signal having an echo amplitude of the reference object is then received. The same applies correspondingly to the second ultrasonic frequency. The use of different ultrasonic frequencies results in different echo amplitudes of the reference object in the first and second echo signals.

[0026] Each echo signal can contain additional echoes from the environment of the ultrasonic sensor, for example as ground echoes. These echoes are not discussed further here, their echo amplitudes often being significantly lower than the echo amplitudes of the reference object.

[0027] The ultrasonic sensor can emit a single ultrasonic pulse and receive the corresponding echo signal, or the ultrasonic sensor emits a pulse sequence of single ultrasonic pulses and receives the corresponding echo signals, respectively.

[0028] The emission sequence of the first and second ultrasonic pulses is essentially arbitrary and can be performed, for example, when emitting a plurality of independent ultrasonic pulses of the first and / or second ultrasonic frequency in any order, including a mixed order. The frequency response of the ultrasonic sensor is adjusted accordingly in order to emit ultrasonic pulses via its ultrasonic membrane and to couple in the corresponding echo signals.

[0029] Receiving the corresponding echo signals includes receiving raw sensor data, which is provided in this form for further processing in order to be able to determine the ratio of the echo amplitudes of the reference object. In principle, a pre-processing of the raw sensor data is possible, for example using filters. Accordingly, the raw data is transmitted from the ultrasonic sensor to a control unit, in which further steps of the method are performed.

[0030] Determining the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal involves, inter alia, the echo amplitudes originating from the reference object. These echo amplitudes of the reference object are generally detectable as peaks in the amplitude curves of the corresponding received echo signals over time. For example, the ratio is determined as the amplitude of the echo signal received at the lower ultrasonic frequency divided by the amplitude of the echo signal received at the higher ultrasonic frequency. In this case, a misplacement of the ultrasonic sensor is detected from the fact that the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal is at least one specified threshold value below a correct placement of the ultrasonic sensor. However, it is also possible to determine the ratio in the reverse manner, whereby a misplacement of the ultrasonic sensor can be detected from the fact that the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal is at least one specified threshold value above a correct placement of the ultrasonic sensor.

[0031] The order of the method steps shown here is only an example. The steps can be performed in a different order without any fundamental change to the method.

[0032] In an advantageous configuration of the application, the positioning of the reference object in the detection area of the ultrasonic sensor comprises detecting the position of the reference object in the detection area of the ultrasonic sensor based on the echo signals received using the plurality of ultrasonic sensors. Thus, the sensor device comprises a plurality of ultrasonic sensors having partially overlapping detection areas such that the reference object can be detected by the plurality of ultrasonic sensors. The plurality of ultrasonic sensors can or can not comprise the ultrasonic sensor whose installation is to be checked. In general, different configurations are possible for using the plurality of ultrasonic sensors for detecting the position of the reference object in the detection area of the ultrasonic sensor. For example, each ultrasonic sensor can independently emit ultrasonic signals and receive echo signals based thereon. Furthermore, when an ultrasonic signal is emitted from one of the ultrasonic sensors, the plurality of ultrasonic sensors can receive echo signals based on this signal, provided that the ultrasonic sensors are synchronized. The echo signals can be processed as raw data. Alternatively, it can be sufficient to detect and process distance information related to the reference object in the echo signals for detecting the position of the reference object. Preferably, in this case adjacent ultrasonic sensors are used such that their detection areas exist at least partially overlapping and echo of the reference object can be received from the plurality of ultrasonic sensors. Based on the received echo signals, for example, known multi-point measurement methods, in particular trilateration methods, can be used for detecting the position of the reference object in the detection area 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 estimation of the object can be performed in a known 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 a wall, i.e. whether the object has a large width, can be performed in a known manner.

[0033] In an advantageous configuration of the application, the positioning of the reference object in the detection area of the ultrasonic sensor comprises the emission of at least one focused ultrasonic pulse by means of the ultrasonic sensor having a narrow detection area and the reception of at least one corresponding echo signal by means of the ultrasonic sensor, wherein the reference object is positioned by finding the echo of the reference object contained in the at least one received echo signal in the detection area of the ultrasonic sensor. As mentioned above, the detection area of the ultrasonic sensor depends on the frequency, the detection area being narrower, thus the focus being on higher frequencies. This leads to a directional characteristic of the ultrasonic sensor compared to lower frequencies. Thus, if a corresponding echo signal is received based on a focused ultrasonic signal, i.e. an ultrasonic signal having a high frequency with a narrow beam lobe and a high directional characteristic, and the echo of the object is found in the echo signal, the object has a suitable placement as a reference object, which means that it can also be found in a wider detection area for lower frequencies. If the reference object is located in a narrow detection area, the method can continue. It is ensured that at least for ultrasonic pulses having a wider detection area, the reference object is located in the central region of the respective detection area. Due to the focus of the ultrasonic signal, the reference object is preferably located at a certain distance from the ultrasonic sensor, so that it can also be detected with less focused ultrasonic signals of lower frequencies. Preferably, the positioning of the reference object is based on the emission of at least one first or second ultrasonic pulse having a first or second ultrasonic frequency using the ultrasonic sensor and the reception of a corresponding echo signal. Depending on which ultrasonic signal has a higher frequency, the emission of this ultrasonic signal represents the emission of at least one focused ultrasonic pulse having a narrow detection area. It is thus advantageous to first emit at least one ultrasonic signal having a higher frequency in order to position the reference object, so that no additional ultrasonic pulses need to be emitted for the positioning. This applies at least to the case that the reference object is located in a narrow detection area. The emission of at least one focused ultrasonic pulse with the ultrasonic sensor having a narrow detection area can correspond, for example, to the operation of the ultrasonic sensor at a nominal frequency. Alternatively, at least one focused ultrasonic pulse is emitted at a frequency higher than the nominal frequency. The only important factor is that at least the first or second ultrasonic frequency is not higher than the frequency used for emitting at least one focused ultrasonic pulse. Preferably, the first and second ultrasonic frequencies are not higher than the frequency used for emitting at least one focused ultrasonic pulse, if at least one focused ultrasonic pulse is neither at least one first ultrasonic pulse nor at least one second ultrasonic pulse.

[0034] In an advantageous configuration of the application, positioning the reference object in the detection area of the ultrasonic sensor comprises detecting the position of the reference object in the detection area of the ultrasonic sensor based on a detection of the surroundings using at least one of the environment sensors from the group of optical camera, LiDAR-based environment sensor and radar sensor. This means that sensor information of additional environment sensors located on the vehicle is used to detect the position of the reference object. The above statements regarding the determination of the reference object position apply accordingly.

[0035] In an advantageous configuration of the application, the method comprises an additional step for positioning the reference object in a central region of the detection area of the ultrasonic sensor, preferably within an angular range of + / - 15°, further preferably within an angular range of + / - 10° and particularly preferably within an angular range of + / - 5°, in particular at an angle of approximately 0° with respect to the central axis of the mounting bracket of the ultrasonic sensor. In the central region of the detection area, the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal is of particular interest. It also prevents the reference object from being located on the edge of the detection area and possibly not being 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 mounting bracket. The angular range relates to the orientation in the horizontal plane. Positioning the reference object in the central region of the detection area of the ultrasonic sensor can comprise excluding objects located outside the central region. However, advantageously, the positioning is performed in such a way that instructions are output to move the vehicle and / or the reference object in order to position the reference object accordingly. Thus, the reference object is preferably positioned in conjunction with the positioning of the reference object in the detection area of the ultrasonic sensor. The positioning can thus be repeated as required until the reference object is positioned in the central region. Particularly preferably, the vehicle autonomously performs the positioning with respect to the reference object in order to position the reference object in the central region.

[0036] In an advantageous configuration of the application, at least one of the first and second ultrasonic frequencies lies in a frequency range below the nominal frequency of the ultrasonic sensor, and the respective other ultrasonic frequency is higher than the first ultrasonic frequency, in particular higher than the nominal frequency. The frequency difference between the first and second ultrasonic frequencies is particularly relevant. However, it has proven advantageous for conventional ultrasonic sensors for the first or second ultrasonic frequency to be below the nominal frequency of the ultrasonic sensor. It is further advantageous for the other ultrasonic frequency to be higher than the nominal frequency of the ultrasonic sensor. It is particularly preferred for the values of the first and second ultrasonic frequencies to be equidistant from the nominal frequency. For example, it has proven advantageous to use approximately 46 kHz and 59 kHz as the first and second ultrasonic frequencies. It has also proven effective to use approximately 49 kHz and 55 kHz as the first and second ultrasonic frequencies. The same applies to frequencies between the specified values. For ordinary ultrasonic sensors, it is possible to use approximately 49 kHz and 55 kHz as the first and second ultrasonic frequencies in a standard operating mode of the typical ultrasonic sensor, and thus to implement it particularly simply. The typical nominal frequency of the ultrasonic sensor lies in a range between 49 kHz and 55 kHz, in particular approximately 52 kHz.

[0037] In an advantageous configuration of the application, 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 determining the ratio of the 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. This allows using a statistical approach to determine the echo amplitudes of the reference object and / or the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal based on a plurality of first and second echo signals. Accordingly, the echo amplitudes of the reference object and / or the ratio of the echo amplitudes in the at least one first and second echo signal can be determined as, for example, an average, a weighted average and / or a median value. Thus, the echo amplitudes of the reference object in the at least one first and second echo signal can first be determined in accordance with a specified determination, on the basis of which the ratio of the amplitudes of the first and second echo signals can then be formed. Alternatively, for any combination of first and second echo signals, individual ratios can first be determined, and then the ratio in question can be determined based on these individual ratios. By using a plurality of echo signals, a higher confidence in the ratio of the echo amplitudes of the reference object in the at least one first and second echo signal can be achieved, and thus a correct installation of the ultrasonic sensor. By increasing the confidence in the echo amplitude ratio, false detections of an incorrect installation of the ultrasonic sensor can be reliably avoided. For example, limit values can be chosen which are particularly close to the ratio of a correct installation of the ultrasonic sensor.

[0038] In an advantageous configuration of the application, the method comprises a step for determining the position of the reference object in the detection area of the ultrasonic sensor, and outputting a misplacement of the ultrasonic sensor comprises outputting a misplacement 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 placement of the ultrasonic sensor at least one specified threshold value, which depends on the position of the reference object in the detection area of the ultrasonic sensor.

[0039] In an advantageous configuration of the application, the method comprises a step for determining the position of the reference object in the detection area of the ultrasonic sensor, and outputting a misplacement of the ultrasonic sensor comprises outputting a misplacement 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 placement of the ultrasonic sensor at least one specified threshold value, which depends on the position of the reference object in the detection area of the ultrasonic sensor.

[0040] The two cases described above relate to a position-dependent evaluation of the echo amplitudes of the reference object in the received echo signals. Thus, even in the case of a correct placement 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 placement 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 found to be approximately 1, a deviation can have occurred when the position is different. In order to be able to check the placement of the ultrasonic sensor particularly reliably, the position of the reference object is therefore taken into account, either by a correct placement ratio that depends on the position of the reference object, or by a threshold value that depends on the position of the reference object. In particular, the position of the reference object is an angular position in the horizontal plane. Due to the combination of the correct placement ratio and the threshold value that depends on the position of the reference object, it should only be necessary to determine one position of the reference object. BRIEF DESCRIPTION OF DRAWINGS

[0041] The application is explained in greater detail below with reference to the drawings based on preferred embodiments. The features shown can each represent an aspect of the application, alone or in combination. Features of different exemplary embodiments can be transferred from one exemplary embodiment to another.

[0042] In the drawings:

[0043] Figure 1 A schematic view of an ultrasonic sensor according to a first preferred embodiment is shown in a mounting bracket, in which the ultrasonic sensor is correctly placed and engaged in the mounting bracket,

[0044] Figure 2 A schematic view of an ultrasonic sensor according to a second preferred embodiment is shown in a mounting bracket, in which the ultrasonic sensor is incorrectly placed and engaged in the mounting bracket, Figure 1Schematic illustration of an ultrasonic sensor in a mounting bracket, wherein the ultrasonic sensor is not properly seated and not fully engaged in the mounting bracket,

[0045] Figure 3 Illustration of a detection area map of an ultrasonic sensor properly seated and engaged in a mounting bracket at a medium ultrasonic frequency according to Figure 1 Illustration of a detection area map of an ultrasonic sensor not properly seated in a mounting bracket and thus not fully engaged in the mounting bracket at a medium ultrasonic frequency according to Figure 2

[0046] Figure 4 Illustration of a detection area map of an ultrasonic sensor properly seated and engaged in a mounting bracket at a high first ultrasonic frequency according to Figure 1 Illustration of a detection area map of an ultrasonic sensor not properly seated in a mounting bracket and thus not fully engaged in the mounting bracket at a high first ultrasonic frequency according to Figure 2

[0047] Figure 5 Illustration of a detection area map of an ultrasonic sensor properly seated and engaged in a mounting bracket at a low second ultrasonic frequency according to Figure 1 Illustration of a detection area map of an ultrasonic sensor not properly seated in a mounting bracket and thus not fully engaged in the mounting bracket at a low second ultrasonic frequency according to Figure 2

[0048] Illustration of a plot of the ratio of the echo amplitudes of a reference object in the first and second echo signals as a function of the angular position of the reference object for an ultrasonic sensor properly seated in a mounting bracket and engaged according to Figure 6 Illustration of a plot of the ratio of the echo amplitudes of a reference object in the first and second echo signals as a function of the angular position of the reference object for an ultrasonic sensor not properly seated in a mounting bracket and thus not fully engaged in the mounting bracket according to Figure 1 Figure 2 Illustration of a flowchart of a first method for checking the seating of an ultrasonic sensor on a vehicle in

[0049] and Figure 7 Figure 1 2 Illustration of a flowchart of a second method for checking the seating of an ultrasonic sensor on a vehicle in and

[0050] Figure 8 Figure 1 2

[0051] Figure 9 Illustration of a schematic diagram of a vehicle with a sensor assembly having a plurality of ultrasonic sensors from​​​​​​Figure 1 and 2 an ultrasonic sensor and a control unit connected to a plurality of ultrasonic sensors. DETAILED DESCRIPTION

[0052] Figure 1 An ultrasonic sensor 10 according to the first preferred embodiment is shown.

[0053] The ultrasonic sensor 10 comprises a sensor housing 12 on which two latch protrusions 14 are formed which are diametrically opposite to each other. The ultrasonic sensor 10 further comprises a sensor head with an ultrasonic membrane which is not visible in Figure 1 The control and evaluation electronics are arranged within the sensor housing 12. The sensor housing 12 is closed with a cover 16. In Figure 1 In the shown embodiment, the receptacle 18 protrudes in radial direction from the proximal end of the sensor housing 12. It is to be understood that in other embodiments the receptacle 18 can also protrude from the proximal end of the sensor housing at other angles.

[0054] The ultrasonic sensor 10 is accommodated in a mounting bracket 20. For this purpose, the mounting bracket 20 comprises two latch arms 22 with latch openings which are not shown here. The latch arms 22 can be sprung in radial direction and serve for holding and fastening the ultrasonic sensor 10. When the ultrasonic sensor 10 is correctly positioned in the mounting bracket 20, the two latch protrusions 14 engage in the respective openings of the latch arms 22 and the ultrasonic sensor 10 is correctly positioned and firmly held in the sensor mounting bracket 20.

[0055] The ultrasonic sensor 10 is part of a sensor arrangement 30 with a plurality of ultrasonic sensors 10 and a control unit 32 which is connected to the ultrasonic sensors 10 via a data connection 34. In principle, the control unit 32 can be any desired data processing device. In the automotive sector, so-called embedded systems are often used. The term ECU (Electronic Control Unit) is used for such a control unit 32. The data link 34 can comprise a bus, for example in the form of a DSI3 bus, a CAN bus, FlexRay or as a proprietary implementation. However, in principle, a direct data link 34 between the control unit 32 and each ultrasonic sensor 10 is also possible.

[0056] As shown in Figure 9 In this exemplary embodiment, the ultrasonic sensors 10 of the sensor arrangement 30 are mounted on the rear side and on the front side of a vehicle 36. For this purpose, the mounting brackets 20 of the ultrasonic sensors 10 are fixed to the rear side and to the front side of the vehicle 36, for example on the front or rear fender of the vehicle 36.

[0057] Figure 2 A first preferred embodiment of theFigure 1 ultrasonic sensor 10.

[0058] However, contrary to the illustration in Figure 1 only one of the two latching protrusions 14 of the ultrasonic sensor 10 is engaged in the respective opening of one of the latching arms 22. As a result, the ultrasonic sensor 10 is not properly seated. As a consequence, the ultrasonic sensor 10 is assumed to be firmly fixed in the mounting bracket 20, but in fact it is tilted and thus not properly seated in the mounting bracket 20. This improper seating of the ultrasonic sensor 10 in the mounting bracket 20 leads to a position and / or angle of the sensor axis relative to the central axis 42 of the mounting bracket 20 which can result in an incorrect operation of the ultrasonic sensor 10 and, in addition, in a malfunction of a driver assistance system using the ultrasonic sensor 10.

[0059] In order to be able to detect such a case of improper seating, a first method for checking the seating of an ultrasonic sensor 10 in a mounting bracket 20 on a vehicle 36 as shown in Figure 7 is described below. The method is performed under control of the control unit 32. The control unit 32 can individually control each ultrasonic sensor 10 of the sensor assembly 30 via the data link 34 in order to perform the method described below. The method is additionally described with reference to Figures 3 to 6 .

[0060] The method starts with a step S100 which involves positioning a reference object in the detection area 40 of the ultrasonic sensor 10. The detection area 40 here defines a region in which echoes of the reference object at the first and second ultrasonic frequencies can be received. The detection area 40 is defined with respect to a proper seating of the ultrasonic sensor 10, wherein the sensor axis of the ultrasonic sensor 10 corresponds to the central axis 42 of the mounting bracket 20, which also defines a proper seating of the ultrasonic sensor 10. For the nominal frequencies, i.e. in the intermediate frequency range, Figure 3 The detection areas 40a, 40b for a proper seating of the ultrasonic sensor 10 in the mounting bracket 20 as shown in Figure 1 , and for an improper seating of the ultrasonic sensor 10 in the mounting bracket 20 as shown in Figure 2 , are accordingly shown.

[0061] Positioning a reference object in the detection area 40 of the ultrasonic sensor 10 comprises detecting a suitable reference object in the detection area 40. Thus, the object has to be suitable as a reference object and be located in the detection area 40 of the ultrasonic sensor 10.

[0062] For this purpose, the positioning of the reference object in the detection area 40 of the ultrasonic sensor 10 is performed on the basis of the echo signals received with the plurality of ultrasonic sensors 10. For example, ultrasonic signals are automatically emitted from all ultrasonic sensors 10 located in the front of the vehicle 36, and echo signals based on these ultrasonic signals are received in order to perform the method for the ultrasonic sensors 10 of the front of the vehicle 36. Distance information with respect to the reference object is detected and processed in the echo signals in order to detect the position of the reference object. For example, known multilateration methods, in particular trilateration methods, are used to detect the position of the reference object in the detection area 40 of the ultrasonic sensor 10. Furthermore, on the basis of the received echo signals, it is determined whether the object is suitable as a reference object. For this purpose, on the basis of the received echo signals, a height estimation of the object is made in a known manner. The reference object is preferably located in the same height range as the ultrasonic sensor 10. Furthermore, on the basis of the received echo signals, a detection of, for example, a wall is performed in a known manner in order to exclude such objects. The position of the reference object is determined with respect to the ultrasonic sensor 10 as an angle in a horizontal plane and as a distance.

[0063] Step S110 relates to positioning the reference object in a central region of the detection area 40 of the ultrasonic sensor 10, preferably in an angular range of + / - 15°, further preferably in an angular range of + / - 10°, and particularly preferably in an angular range of + / - 5°, in particular at an angle of approximately 0° with respect to the central axis 42 of the mounting bracket 20, which corresponds to the sensor axis of the ultrasonic sensor 10 when the ultrasonic sensor 10 is correctly positioned.

[0064] On the basis of the position of the reference object determined in step S100, an instruction is output to move the vehicle 36 and / or the reference object in order to position the reference object with respect to the vehicle 36 and thus with respect to the ultrasonic sensor 10. The reference object is thus preferably positioned in conjunction with the positioning of the reference object in the detection area 40 of the ultrasonic sensor 10. The positioning is thus checked again in a further step S100, and if necessary, the positioning of the reference object is also repeated until the reference object has the desired positioning in the central region of the detection area 40. Preferably, the vehicle 36 autonomously performs the positioning with respect to the reference object in order to position the reference object in the central region of the detection area 40.

[0065] Step S120 relates to emitting first ultrasonic pulses with a first ultrasonic frequency by means of the ultrasonic sensor 10. The first ultrasonic frequency here is a frequency of approximately 59 kHz. The ultrasonic sensor 10 here, for example, has a nominal frequency of 52 kHz, so that the first ultrasonic frequency is higher than the nominal frequency.

[0066] Step S130 involves receiving a first echo signal of a first ultrasonic frequency by the ultrasonic sensor 10. In Figure 4 a correct positioning of the ultrasonic sensor 10 in the mounting bracket 20 and an incorrect positioning of the ultrasonic sensor 10 in the mounting bracket 20 is shown. The 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. Figure 1 Figure 2 a correct positioning of the ultrasonic sensor 10 in the mounting bracket 20 and an incorrect positioning of the ultrasonic sensor 10 in the mounting bracket 20 is shown. The 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.

[0067] Step S140 involves emitting a second ultrasonic pulse of a second ultrasonic frequency by means of the ultrasonic sensor 10. Here, the second ultrasonic frequency is a frequency of about 46 kHz, thus lower than the nominal frequency.

[0068] Step S150 involves receiving a second echo signal of the second ultrasonic frequency by the ultrasonic sensor 10. In Figure 5 a correct positioning of the ultrasonic sensor 10 in the mounting bracket 20 and an incorrect positioning of the ultrasonic sensor 10 in the mounting bracket 20 is shown. The 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. Figure 1 Figure 2 Step S160 comprises determining a ratio of echo amplitudes of the reference object in the first and second echo signals. a correct positioning of the ultrasonic sensor 10 in the mounting bracket 20 and an incorrect positioning of the ultrasonic sensor 10 in the mounting bracket 20 is shown. The 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.

[0069] Figure 6 a correct positioning of the ultrasonic sensor 10 in the mounting bracket 20 and an incorrect positioning of the ultrasonic sensor 10 in the mounting bracket 20 is shown. The 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. Figure 1 Figure 2 a correct positioning of the ultrasonic sensor 10 in the mounting bracket 20 and an incorrect positioning of the ultrasonic sensor 10 in the mounting bracket 20 is shown. The 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] Appropriate detection and processing of the echo amplitude levels of the reference object in the first and second echo signals is performed. This processing takes place in the control unit 32.

[0071] Step S170 involves outputting a positioning error of the ultrasonic sensor 10 if the ratio 44 of echo amplitudes of the reference object in the first and second echo signals deviates from the ratio of a correct positioning of the ultrasonic sensor 10 by at least one specified threshold value. The output is provided by the control unit 32.

[0072] If the ratio 44 of echo amplitudes of the reference object in the first and second echo signals deviates from the ratio of a correct positioning of the ultrasonic sensor 10 by at least one predetermined threshold value, which depends on the position of the reference object in the detection area 40 of the ultrasonic sensor 10, a positioning error of the ultrasonic sensor 10 is output. As​​​Figure 6 The ratio curves of the echo amplitudes each depend on the position of the reference object in the detection area 40 determined in step S100, as is shown. This leads to a position-dependent evaluation of the ratio of the echo amplitudes of the reference object in the received echo signals.

[0073] The second method for checking the installation of the ultrasonic sensor 10 in the mounting bracket 20 on the vehicle 36 is described below as Figure 8 The second method is also performed with the sensor assembly 30 described above. The method is performed under the control of the control unit 32. The control unit 32 can individually control each ultrasonic sensor 10 of the sensor assembly 30 via the data link 34 in order to perform the method described below. The second method is partly identical to the first method, so that here only the differences between the two methods are essentially described.

[0074] As described previously with reference to the first method, the second method begins with a step S120 which involves emitting, by means of the ultrasonic sensor 10, a first ultrasonic pulse having a first ultrasonic frequency. The first ultrasonic frequency here is also a frequency of approximately 59 kHz. Here, the ultrasonic sensor 10 has, for example, a nominal frequency of 52 kHz, so that the first ultrasonic frequency is higher than the nominal frequency.

[0075] A step S130 involves receiving, by means of the ultrasonic sensor 10, a first echo signal of the first ultrasonic frequency. In Figure 4 The detection areas 40a, 40b corresponding to a correct installation of the ultrasonic sensor 10 in the mounting bracket 20 as Figure 1 and an incorrect installation of the ultrasonic sensor 10 in the mounting bracket 20 as Figure 2 are shown in Fig. 6. The 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.

[0076] The step S135 comprises positioning a reference object in the detection area 40 of the ultrasonic sensor 10. Here, the detection area 40 also defines a region in which echoes of the reference object of the first and second ultrasonic frequencies can be received. The detection area 40 is defined with respect to a correct installation of the ultrasonic sensor 10, wherein the sensor axis of the ultrasonic sensor 10 corresponds to the central axis of the mounting bracket 20, which defines a correct installation of the ultrasonic sensor 10.

[0077] Positioning the reference object in the detection area 40 of the ultrasonic sensor 10 comprises detecting a suitable reference object in the detection area 40.

[0078] Accordingly, a reference object is determined in the received first echo signal. The received first echo signal is based on the emission of a first ultrasound wave pulse having a high frequency of 59 kHz, which means that the first ultrasound wave pulse is a focused ultrasound wave pulse, resulting in a narrow detection area 40 for receiving the first echo signal with the ultrasound wave sensor 10.

[0079] If the echo of the reference object is contained in the first echo signal, this will be located in the detection area 40 of the ultrasound wave sensor 10. The object has a suitable placement as a reference object, which will also allow it to be detected in a wider detection area 40 at a lower frequency.

[0080] Step S140 involves emitting a second ultrasound wave pulse having a second ultrasound wave frequency by means of the ultrasound wave sensor 10. Here, the second ultrasound wave frequency is a frequency of approximately 46 kHz, thus lower than the nominal frequency of the ultrasound wave sensor 10.

[0081] Step S150 involves receiving a second echo signal of the second ultrasound wave frequency by means of the ultrasound wave sensor 10. In Figure 5 detection areas 40a, 40b corresponding to a correct placement of the ultrasound wave sensor 10 in the mounting bracket 20 as Figure 1 illustrated and an incorrect placement of the ultrasound wave sensor 10 in the mounting bracket 20 as Figure 2 illustrated. The sensor raw data transmitted from the ultrasound wave sensor 10 to the control unit 32 is also received as the second echo signal.

[0082] Step S160 comprises determining a ratio of the echo amplitude of the reference object in the first and second echo signals. Figure 6 The corresponding ratio 44 is illustrated in Figure 1 where the ratio 44a for a correct placement of the ultrasound wave sensor 10 in the mounting bracket 20 as Figure 2 illustrated and the ratio 44b for an incorrect placement of the ultrasound wave sensor 10 in the mounting bracket 20 as

[0083] A suitable detection and processing of the echo amplitude level of the reference object in the first and second echo signals is performed.

[0084] Step S170 involves outputting a placement error of the ultrasound wave sensor 10 if the ratio 44 of the echo amplitude of the reference object in the first and second echo signals deviates from the ratio for a correct placement of the ultrasound wave sensor 10 by at least one specified threshold value. Unlike the first method, in the second method the threshold value is independent of the exact position of the reference object, since the exact position is not determined.

[0085] In Figure 8In the second method shown, the dedicated detection mode can be omitted if the ultrasonic sensor 10 emits at high and low frequencies alternately in normal operation. This helps to avoid dead times in normal operation. This also allows continuous checking.

[0086] List of reference signs

[0087] 10 ultrasonic sensor

[0088] 12 sensor housing

[0089] 14 latching protrusion

[0090] 16 cover

[0091] 18 receptacle

[0092] 20 mounting bracket

[0093] 22 latching arm

[0094] 30 sensor assembly

[0095] 32 control unit

[0096] 34 data link

[0097] 36 vehicle

[0098] 40 detection region

[0099] 40a detection region, correct installation

[0100] 40b detection region, incorrect installation

[0101] 42 center axis

[0102] 44 ratio of echo amplitudes

[0103] 44a ratio of echo amplitudes, correct installation

[0104] 44b ratio of echo amplitudes, correct installation

Claims

1. A method for inspecting the placement of an ultrasonic sensor (10) on a vehicle (36), wherein the ultrasonic sensor (10) is mounted in a mounting bracket (20) on the vehicle (36), the method comprising the steps of: A reference object is located in the detection area (40) of the ultrasonic sensor (10). At least one first ultrasonic pulse having a first ultrasonic frequency is emitted by means of the ultrasonic sensor (10). The ultrasonic sensor (10) receives at least one first echo signal at the first ultrasonic frequency. At least one second ultrasonic pulse having a second ultrasonic frequency is emitted by means of the ultrasonic sensor (10). The ultrasonic sensor (10) receives at least one second echo signal at the second ultrasonic frequency. Determine the ratio (44) of the echo amplitude of the reference object in the at least one first and second echo signals, and If the ratio (44) of the echo amplitude of the reference object in at least one first and second echo signals deviates from the ratio (44) of the correct placement of the ultrasonic sensor (10) by at least one specified threshold, then the placement error of the ultrasonic sensor (10) is output.

2. The method according to claim 1, characterized in that, Locating a reference object in the detection area (40) of the ultrasonic sensor (10) includes detecting the position of the reference object in the detection area (40) of the ultrasonic sensor (10) based on echo signals received using multiple ultrasonic sensors (10).

3. The method according to any one of the preceding claims, characterized in that, Locating a reference object in the detection area (40) of the ultrasonic sensor (10) involves emitting at least one focused ultrasonic pulse by means of the ultrasonic sensor (10) having a narrow detection area (40), and receiving at least one corresponding echo signal by means of the ultrasonic sensor (10), wherein the reference object is located by finding the echo of the reference object contained in the at least one received echo signal in the detection area (40) of the ultrasonic sensor (10).

4. The method according to claim 1 or 2, characterized in that, Locating a reference object in the detection area (40) of the ultrasonic sensor (10) includes detecting the position of the reference object in the detection area (40) of the ultrasonic sensor (10) based on the detection of the surrounding environment using at least one of an environmental sensor, an optical camera, a LiDAR-based environmental sensor, and a radar sensor.

5. The method according to claim 1 or 2, characterized in that, The method includes an additional step of placing the reference object in the central region of the detection area (40) of the ultrasonic sensor (10).

6. The method according to claim 1 or 2, characterized in that, At least one of the first ultrasonic frequency and the second ultrasonic frequency is in a frequency range lower than the nominal frequency of the ultrasonic sensor (10), and the corresponding other ultrasonic frequency is higher than the first ultrasonic frequency.

7. The method according to claim 1 or 2, characterized in that, The method includes repeatedly transmitting the at least one first ultrasonic pulse and / or 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. Determining the ratio (44) of the echo amplitude of the reference object in at least one first and second echo signals includes determining the ratio (44) of the echo amplitude of the reference object based on a plurality of first and second echo signals.

8. The method according to claim 1 or 2, characterized in that... The method includes the step of determining the position of the reference object within the detection area (40) of the ultrasonic sensor (10), and The output of the placement error of the ultrasonic sensor (10) includes: if the ratio (44) of the echo amplitude of the reference object in the at least one first and second echo signals deviates from the ratio (44) of the correct placement of the ultrasonic sensor (10) by at least a specified threshold, the ultrasonic sensor (10) placement error is output, the threshold depending on the position of the reference object in the detection area (40) of the ultrasonic sensor (10).

9. The method according to claim 1 or 2, characterized in that, The method includes the step of determining the position of the reference object in the detection area of ​​the ultrasonic sensor (10), and The output of the ultrasonic sensor (10) placement error includes: if the ratio (44) of the echo amplitude of the reference object in the at least one first and second echo signals deviates from the ratio (44) of the correct placement of the ultrasonic sensor (10) by at least a predetermined threshold, the ultrasonic sensor (10) placement error is output, the threshold depending on the position of the reference object in the detection area (40) of the ultrasonic sensor (10).

10. The method according to claim 5, characterized in that, The reference object is within an angle range of + / -15° relative to the central axis (42) of the mounting bracket (20) of the ultrasonic sensor (10).

11. The method according to claim 5, characterized in that, The reference object is within an angle range of + / -10° relative to the central axis (42) of the mounting bracket (20) of the ultrasonic sensor (10).

12. The method according to claim 5, characterized in that, The reference object is within an angle range of + / -5° relative to the central axis (42) of the mounting bracket (20) of the ultrasonic sensor (10).

13. The method according to claim 5, characterized in that, The reference object is at an angle of 0° relative to the central axis (42) of the mounting bracket (20) of the ultrasonic sensor (10).

14. The method according to claim 6, characterized in that, The corresponding ultrasonic frequency is higher than the nominal frequency.

15. A sensor assembly (30) having at least one ultrasonic sensor (10) and a control unit (32), the control unit being connected to the at least one ultrasonic sensor (10) via a data link (34), wherein, The at least one ultrasonic sensor (10) is mounted in a mounting bracket (20) on the vehicle (36). Its features are, The sensor assembly (30) is designed to perform a method for inspecting the placement of an ultrasonic sensor (10) on a vehicle (36) according to any one of claims 1 to 14.

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