Control device and operating method for ultrasonic sensor, ultrasonic sensor, kit comprising control device and ultrasonic sensor, and motor vehicle

Abstract

The invention relates to a control device (50) for an ultrasonic sensor (1, 100) of a motor vehicle (80). The control device (50) comprises: a first unit (52) configured to determine a sensor characteristic of the ultrasonic sensor (1, 100) during normal operation of the motor vehicle (80); a second unit (53) configured to evaluate an effect of the determined sensor characteristic on whether an operating parameter of the ultrasonic sensor (1, 100) is to be adjusted; and a third unit (54) configured to adjust the operating parameter of the ultrasonic sensor (1, 100) based on the determined sensor characteristic if the second unit (53) assesses that the operating parameter is to be adjusted.

Description

Technical Field

[0001] The invention relates to a control device for an ultrasonic sensor, a method for operating an ultrasonic sensor, an ultrasonic sensor, a kit comprising a control device and an ultrasonic sensor, and a motor vehicle. Background Art

[0002] Modern motor vehicles are equipped with ultrasonic sensors, which allow the motor vehicle's environment to be measured by sending and receiving ultrasonic signals. The information about the vehicle's environment obtained in this way can be evaluated by driver assistance systems in order to generate warnings for the driver and enable autonomous parking or partially or fully autonomous driving.

[0003] The ultrasonic diaphragm of the ultrasonic sensor that transmits and receives ultrasonic signals is mounted flush with the outer shell of the motor vehicle and is therefore visible from the outside. The customer therefore wants the ultrasonic diaphragm to be painted the same color as the outer shell of the motor vehicle.

[0004] The mass and stiffness of the ultrasonic membrane are changed by spraying. The resonance frequency and / or conversion efficiency of the ultrasonic membrane are also changed accordingly, which must be taken into account when operating the ultrasonic sensor.

[0005] During the manufacture of ultrasonic sensors, they are usually sprayed and calibrated in mass production, ie by the supplier. The respective ultrasonic sensors have been calibrated by the supplier on the basis of a respective mass-produced sprayed prototype which has been checked under laboratory conditions.

[0006] However, the customer may subsequently want to repaint his car in a different color. It is also not logistically feasible to stock ultrasonic sensors with all possible paint finishes as spare parts in the aftermarket. In addition, manufacturers of high-end vehicles sometimes produce small series with special paint finishes, so it is not economical to order pre-painted ultrasonic sensors in large series.

[0007] DE 20 2004 021 873 U1 discloses a diaphragm pot for an ultrasonic transducer, which has a wall carrying a diaphragm which can be excited to generate vibrations, wherein the diaphragm pot is provided with a galvanic coating at least in the region of the diaphragm at least on the outside of the diaphragm pot. The diaphragm thickness is selected such that the diaphragm pot has a specific resonance frequency after the galvanic coating has been applied.

[0008] EP 1 855 093 A1 discloses a method for adjusting the resonant frequency of an oscillating part of an ultrasonic sensor housing. The method comprises measuring the resonant frequency of the oscillating part with a measuring device; comparing the measured resonant frequency with a predetermined threshold value of a target resonant frequency; and performing material removal or application on the oscillating part based on the comparison in order to adjust the resonant frequency of the oscillating part. Summary of the invention

[0009] Against this background, it is an object of the invention to enable the ultrasonic sensor to be painted after leaving the manufacturer's premises.

[0010] According to a first aspect, in order to achieve the object, a control device for an ultrasonic sensor of a motor vehicle is proposed, comprising: a first unit, which is configured to determine a sensor characteristic of the ultrasonic sensor during normal operation of the motor vehicle; a second unit, which is configured to evaluate the determined sensor characteristic in order to determine whether an operating parameter of the ultrasonic sensor is to be adjusted; and a third unit, which is configured to adjust the operating parameter of the ultrasonic sensor based on the determined sensor characteristic if the second unit evaluates that the operating parameter is to be adjusted.

[0011] If a motor vehicle is equipped with the proposed control device, the control device can recalibrate the ultrasonic sensor during regular operation of the motor vehicle if the ultrasonic sensor has been repainted, for example by the owner of the motor vehicle, by a repair shop when installing an aftermarket spare part or during small-scale production after leaving the factory of the ultrasonic sensor manufacturer. Thus, changes in the characteristics of the ultrasonic membrane caused by the repainting can be calibrated out and an unchanged high performance of the ultrasonic sensor can advantageously be maintained.

[0012] In particular, “routine operation of the motor vehicle” means that during the execution of the proposed function of determining and evaluating sensor characteristics and adjusting operating parameters based on the evaluation, laboratory conditions are not present. The proposed function of the control device unit is therefore not a diagnostic function that is activated only in workshop mode, but an operating function. The proposed function can be performed routinely, for example after each actuation of the ignition or start button of the motor vehicle, or after each activation of the control device, etc. Therefore, real conditions exist when the proposed function is executed. This means that there may be obstacles in the field of view of the ultrasonic sensor, the ultrasonic sensor may also be dirty, damaged or iced over. “Routine operation” also refers in particular to the intended use of the motor vehicle after its manufacture.

[0013] Determining the sensor characteristic comprises in particular measuring the sensor characteristic.

[0014] The phrase “evaluating whether an operating parameter of the ultrasonic sensor is to be adjusted” may include evaluating whether adjustment of the ultrasonic sensor is necessary and / or evaluating whether adjustment of the ultrasonic sensor is possible and appropriate.

[0015] For example, an adjustment of the ultrasonic sensor is only necessary if its sensor characteristics have changed. For example, an adjustment of the ultrasonic sensor is only possible and advantageous if the ultrasonic sensor is not dirty, not iced up or blocked by obstacles.

[0016] "Adjusting operating parameters" may also mean calibrating or recalibrating the ultrasonic sensor.

[0017] The operating parameters of the ultrasonic sensor may be operating parameters with which the control device or another control device operates the ultrasonic sensor. However, the operating parameters of the ultrasonic sensor may also be operating parameters that the ultrasonic sensor itself takes into account in its operation.

[0018] Thus, adjusting the operating parameter may include adjusting the operating parameter of the control device in question, with which the control device operates the ultrasonic sensor. Adjusting the operating parameter may also include setting the adjusted operating parameter on the ultrasonic sensor, for example by transmitting the adjusted operating parameter to the ultrasonic sensor together with a command for adjustment or the like.

[0019] Various embodiments are explained below which allow for an automatic assessment of the necessity, possibility and convenience of adjusting operating parameters of a control device.

[0020] According to one embodiment, the evaluation performed by the second unit comprises determining a deviation of the determined sensor characteristic from a sensor characteristic stored in the second unit corresponding to a current operating parameter value of the ultrasonic sensor.

[0021] Advantageously, therefore, it may be automatically assessed whether sensor characteristics have changed and therefore require adjustment of operating parameters.

[0022] For example, previously predefined or measured sensor characteristics - for example when manufacturing the ultrasonic sensor or its prototype in the laboratory - can initially be stored in the second unit. If the second unit assesses that the operating parameters are to be adjusted, it can overwrite the stored sensor characteristics with the currently determined sensor characteristics or with sensor characteristics corresponding to the adjusted operating parameters.

[0023] The sensor characteristics corresponding to the currently set operating parameters can therefore always be stored in the second unit for comparison purposes.

[0024] According to another embodiment, the evaluation performed by the second unit includes evaluating whether an identified deviation of the determined sensor characteristics from the stored sensor characteristics is due to a paint coating of the ultrasonic diaphragm of the ultrasonic sensor, and adjusting the operating parameters only if the identified deviation is due to a paint coating of the ultrasonic diaphragm.

[0025] Thus, it is advantageously possible to distinguish between situations where adjustment of operating parameters is advantageous (i.e. if the ultrasonic sensor has been repainted) and situations where adjustment of operating parameters is disadvantageous (i.e. if the sensor characteristics have changed for other reasons and / or the sensor characteristics are not suitable for recalibration).

[0026] Examples of other causes other than paint coating are dust on the ultrasonic sensor, ice on the ultrasonic sensor, and damage to the ultrasonic sensor.

[0027] According to a further embodiment, the second unit is configured to evaluate whether the operating parameter is to be adjusted by comparing a first distance measurement performed with the ultrasonic sensor with a second distance measurement performed with the same or another ultrasonic sensor.

[0028] In particular, if the deviation of the determined sensor characteristic from the stored sensor characteristic is due to a paint coating, the operating parameters are to be adjusted. If the measurement results of two distance measurements performed in a time-dependent manner with the same ultrasonic sensor or with two different ultrasonic sensors differ significantly from each other, i.e. exceed a predefined threshold, it is assumed that either a temporary obstacle is present in the vicinity of one of the ultrasonic sensors, or dust, ice or damage is affecting one of the ultrasonic sensors, and that an adjustment of the operating parameters is therefore not currently appropriate. However, if the vehicle is repainted, the repainting will likewise affect the measurement results of all ultrasonic sensors, and the different distance measurements will therefore not differ significantly from each other, so that an adjustment of the operating parameters may be advantageous in this case.

[0029] The distance measurement may include, in particular, activating the ultrasonic sensor to emit ultrasonic signals and receive reflected ultrasonic signals and determining the distance to obstacles in the surroundings of the motor vehicle using the signal propagation time between the emission of the ultrasonic signal and the reception of the reflected ultrasonic signal.

[0030] Thus, advantageously a simple possibility is indicated for automatically determining, even in the absence of laboratory conditions, whether an adjustment of an operating parameter is advantageous because a change in the sensor characteristic is due to a coating of paint.

[0031] According to another embodiment, the second unit stores a lookup table containing a plurality of predefined sensor characteristics and related operating parameter values ​​determined in advance by measuring ultrasonic sensors of different sprays under laboratory conditions, and the second unit is configured to evaluate whether to adjust the operating parameter by comparing the determined sensor characteristic with the plurality of predefined sensor characteristics, and / or to determine the operating parameter value to which the third unit is to adjust the operating parameter by referring to the lookup table.

[0032] Thus, advantageously, respective prototypes of the ultrasonic sensor can be sprayed in advance in the laboratory with all expected coating types (e.g. different thicknesses, material consistencies, etc.) and the optimal operating parameters for each prototype determined using laboratory measuring equipment. The information obtained in this way can advantageously be stored in a look-up table and can be used to recalibrate the ultrasonic sensor later when leaving the laboratory.

[0033] Thus, another simple possibility is advantageously shown, which, as an alternative or in addition to the other possibilities disclosed herein, can be used to automatically determine whether an adjustment of an operating parameter is advantageous because a change in the sensor characteristics is due to a known paint coating type and at the same time directly indicate the operating parameter value to which the operating parameter is to be set.

[0034] In particular, if the determined sensor characteristic is sufficiently similar to one of the predefined sensor characteristics and / or a sensor characteristic interpolated from a plurality of predefined sensor characteristics, it may be assessed that the operating parameter is to be adjusted. Furthermore, in this case, the operating parameter value to which the operating parameter is to be adjusted in this case may be taken directly from a lookup table and / or may be interpolated from a plurality of values ​​taken directly from a lookup table.

[0035] According to another embodiment, the second unit includes a physical or data-based model, which is configured to output an assessment of whether the operating parameter is to be adjusted based on the sensor characteristics input into the model, and / or output the operating parameter value to which the operating parameter is to be adjusted, and the second unit is configured to input the determined sensor characteristics into the physical or data-based model, and use the physical or data-based model to assess whether the operating parameter is to be adjusted and / or determine the operating parameter value to which the third unit is to adjust the operating parameter.

[0036] Thus, a further possibility is advantageously indicated which can be applied as an alternative or in addition to the other possibilities disclosed herein in order to automatically determine whether an adjustment of an operating parameter is advantageous even in the absence of laboratory conditions because a change in the sensor characteristics is due to a modelable paint coating, while directly determining the operating parameter value to which the operating parameter is to be set.

[0037] Specifically, the physical model may be a knowledge-based modeling model based on the physical interrelationship between the thickness and weight of the coating layer on the ultrasonic diaphragm, the resulting sensor characteristics, and the operating parameters that are optimal for the corresponding sensor characteristics.

[0038] In particular, the data-based model can be a model obtained using statistical methods by analyzing multiple measured sensor characteristics in different paint coatings and multiple optimal operating parameters determined by the measurements, whereby the parameters of the data-based model are adjusted until the closest possible match is achieved between the model's predictions and the physical reality of the multiple measurements.

[0039] According to another embodiment, the data-based model includes one or more trained neural networks.

[0040] For example, a first neural network can be trained with sensor characteristics measured on differently painted ultrasonic sensor prototypes as input data and with the optimal operating parameters determined in each case by the measurements as output data. A second neural network can be trained with sensor characteristics measured on differently painted ultrasonic sensor prototypes on the one hand and on differently dirty, iced or damaged ultrasonic sensor prototypes on the other hand as training input data and with a corresponding indication as training output data whether the sensor characteristic in question comes from a painted ultrasonic sensor prototype or from a dirty, iced or damaged ultrasonic sensor prototype.

[0041] Advantageously, therefore, no knowledge of the physical interrelationships is required and it is still possible to automatically assess whether and how to conveniently adjust the operating parameters in the absence of laboratory conditions.

[0042] According to another embodiment, the corresponding sensor characteristic determined by the first unit is a transfer function of an electromechanical component of the ultrasonic sensor, and the first unit is configured to apply an electrical test signal to the ultrasonic sensor and to capture an electrical response signal from the ultrasonic sensor in order to determine the sensor characteristic.

[0043] Thus, a purely electrical characterization of the properties of the ultrasonic sensor and its electromechanical components is performed. Thus, advantageously, it is not necessary to create a defined laboratory environment in order to be able to characterize the sensor. The result of determining the sensor characteristics is advantageously independent of whether the ultrasonic sensor is outdoors or whether a distant obstacle (e.g. a garage wall) obscures the ultrasonic sensor, for example.

[0044] The electrical test signal may be a voltage signal or a current signal, and the electrical response signal may be a current signal or a voltage signal.

[0045] The transfer function may advantageously contain all data required to determine operating parameters, such as operating frequency, transmit signal amplitude or receive signal gain.

[0046] The electromechanical components of the ultrasonic sensor include an electromechanical system which is activated by the test signal and by which the receive signal is received, and comprises, for example, an ultrasonic diaphragm, a transducer element attached thereto from the inside and a driver circuit for activating the transducer element.

[0047] According to another embodiment, the operating parameters adjusted by the third unit include one or more of the following parameters: the operating frequency at which the ultrasonic diaphragm of the ultrasonic sensor is excited to generate vibrations, the amplitude of the activation signal used by the driver circuit of the ultrasonic sensor to activate the acoustic transducer element of the ultrasonic sensor, and the amplification factor at which the received signal output by the acoustic transducer element to the driver circuit is amplified.

[0048] Thus, an adequate response to changes in the characteristics of the ultrasonic diaphragm due to application of the paint coating is advantageously achieved.

[0049] According to a second aspect, a method for operating an ultrasonic sensor of a motor vehicle is provided. The method comprises: determining a sensor characteristic of the ultrasonic sensor during normal operation of the motor vehicle; evaluating the determined sensor characteristic in order to determine whether an operating parameter of the ultrasonic sensor is to be adjusted; and if it has been evaluated that the operating parameter is to be adjusted, adjusting the operating parameter of the ultrasonic sensor based on the determined sensor characteristic.

[0050] According to a third aspect, a computer program product is proposed comprising instructions which, when executed by a control unit of a motor vehicle, cause the control unit to perform a method according to the first aspect or one of its embodiments.

[0051] According to a fourth aspect, an ultrasonic sensor is proposed, which has an ultrasonic diaphragm, an acoustic transducer element arranged on the inner side of the ultrasonic diaphragm for vibration excitation and vibration detection of the ultrasonic diaphragm, a driver circuit for activating the acoustic transducer element, and a control device as described in any one of claims 1 to 9.

[0052] According to one embodiment, the ultrasonic membrane of the ultrasonic sensor is at least free of a final coating of paint.

[0053] In particular, the ultrasonic diaphragm may not be sprayed.

[0054] According to a fifth aspect, a kit is proposed, comprising: a control device according to the first aspect or one of its embodiments and / or a computer program product according to the third aspect, and an ultrasonic sensor having an ultrasonic diaphragm, an acoustic transducer element arranged on the inner side of the ultrasonic diaphragm for vibration excitation and vibration detection of the ultrasonic diaphragm, and a driver circuit for activating the acoustic transducer element.

[0055] The ultrasonic sensor and associated control device with the proposed recalibration functionality are preferably sold as a set, in that the control device contains, for example, a look-up table or model of the specific type of ultrasonic sensor that it is configured to recalibrate.

[0056] According to one embodiment, the ultrasonic membrane of the ultrasonic sensor is at least free of a final coating of paint.

[0057] In particular, the ultrasonic diaphragm may not be sprayed.

[0058] Due to the features of the proposed control device, advantageously, there is no need to paint the membrane of the ultrasonic sensor during manufacture and calibrate the ultrasonic sensor after painting during manufacture. Instead, the painting of the ultrasonic sensor can be left to the vehicle manufacturer or customer and only completed when the vehicle receives a final spray coating or repair.

[0059] According to a sixth aspect, a motor vehicle is proposed having a control device according to the first aspect or one of its embodiments, an ultrasonic sensor according to the fourth aspect or one of its embodiments or a kit according to the fifth aspect or one of its embodiments.

[0060] The exemplary embodiments and features described for the proposed control device apply correspondingly to the proposed method, the proposed computer program product, the proposed ultrasonic sensor, the proposed kit and the proposed motor vehicle.

[0061] Other possible implementations of the present invention also include the above or below about the exemplary embodiment described without explicit mention of the feature or embodiment combination. In this case, those skilled in the art will also add a separate aspect as an improvement or addition to the corresponding basic form of the present invention.

[0062] Further advantageous designs and aspects of the invention form the subject matter of the dependent claims and of the exemplary embodiments of the invention described below.The invention is explained in more detail below based on preferred embodiments with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 An example of an ultrasonic sensor is schematically shown;

[0064] Figure 2 Schematically shows a motor vehicle with an ultrasonic sensor and a control device according to an exemplary embodiment;

[0065] Figure 3 shows an example of an ultrasonic sensor Figure 1 Section AA in;

[0066] Figure 4 An equivalent circuit diagram of an example of an ultrasonic sensor is shown;

[0067] Figure 5 Schematically illustrates functional units of a control device according to an exemplary embodiment;

[0068] Figure 6 The steps of a method according to an exemplary embodiment are shown;

[0069] Figure 7 A flow chart illustrating processing steps of an evaluation unit according to an advantageous development of an exemplary embodiment is shown;

[0070] Figure 8 An evaluation unit according to an advantageous development is shown; and

[0071] Fig. 9 An evaluation unit according to an advantageous development is shown.

[0072] Unless stated otherwise, identical or functionally identical elements are provided with the same reference numerals in the figures. DETAILED DESCRIPTION

[0073] Figure 1 A schematic diagram showing an example of an ultrasonic sensor 1 is shown, Figure 2 An example of an ultrasonic sensor 1 is shown. Figure 1 Schematic cross section AA in. Reference Figure 1 and Figure 2 The ultrasonic sensor 1 has a plastic housing 2 which has a housing body 3 , a retaining ring 4 , a cover 5 and an extension section 6 .

[0074] The diaphragm pot 9 is placed on one edge 7 of the housing body, around the opening 8 of the housing body 3, and fixed to the housing body 3 of the plastic housing 2 using the retaining ring 4. The diaphragm pot 9 has a pot shape, and the base of the top shape forms an ultrasonic diaphragm 10. Reference numeral 10 represents the entire ultrasonic diaphragm, and reference numeral 11 represents the outer surface of the ultrasonic diaphragm 10. In particular, the outer surface of the ultrasonic diaphragm 10 is bare or free. This means that the outer surface 11 of the ultrasonic diaphragm is not sprayed (unsprayed).

[0075] A piezoelectric element 12 (an example of an acoustic transducer element) is mounted on the inner surface of the ultrasonic diaphragm 10 opposite to the outer surface 11. The piezoelectric element 12 is connected to the ultrasonic diaphragm 10 by two first contact pins 13 (in the Figure 2 The first contact pin 13 is electrically connected to a driver circuit 16 mounted on a printed circuit board 14 accommodated in the housing body 3 (only one of the first two contact pins 13 can be seen in the cross-sectional view of FIG. 1 ). In this case, a conductor path (not shown) of the printed circuit board 14 establishes the contact between the driver circuit 16 and the contact pin 13, and two thin loose wires 15 establish the contact between the contact pin 13 and the piezoelectric element 12. The thin loose wires 15 provide vibration decoupling between the printed circuit board 10 accommodated in the rigid housing body 3 and the first contact pin 13 on the one hand, and between the vibrating ultrasonic diaphragm 10 and the piezoelectric element 12 attached thereto on the other hand.

[0076] The driver circuit 16 is also in contact with at least two second contact pins 17, which are pressed into the housing body 3 and the extension section 6. The second contact pins 17 provide an external electrical connection to the driver circuit 16.

[0077] Figure 3 A motor vehicle 80 with an ultrasonic sensor 100 and a control device 50 according to an exemplary embodiment is schematically shown.

[0078] The control device 50 is connected to the ultrasonic sensor 100 (having a second contact pin 17, Figure 2 ). The ultrasonic sensor 100 is installed in a chassis component of the motor vehicle 80, such as the front fender 24. The ultrasonic diaphragm 10 of the ultrasonic sensor 100 is arranged in a substantially circular opening 25 of the front fender 24. It should be noted that Figure 3 In FIG. 1 , the dimensions of the opening 25 and the ultrasonic diaphragm 10 are exaggerated.

[0079] The front fender 24 is a chassis component that is painted in a predefined color. Therefore, the customer and the manufacturer also need to paint the ultrasonic diaphragm 10 in the same color as the front fender 24. Figure 3 In the embodiment, the outer surface 11 of the ultrasonic diaphragm 10 ( Figure 1 , 2 ) is not free. Instead, the coating layer 26 is applied to the outer surface 11 ( Figure 1 , 2 With regard to the distinction below between a coated ultrasonic sensor 100 having a coating layer 26 and an uncoated ultrasonic sensor 1 without a coating layer 26 , reference numeral 1 is used for the uncoated ultrasonic sensor 1 ( Figure 1 ), reference numeral 100 is an ultrasonic sensor 100 for spraying ( Figure 2 ). The ultrasonic sensors 1, 100 are designed and configured identically except for the paint layer. The ultrasonic sensors 1, 100 may be the same ultrasonic sensors 1, 100 before or after spraying.

[0080] First refer to Figures 1 to 3The general operation of the ultrasonic sensor 1, 100 for performing distance measurement is schematically described. The distance measurement operation is performed in particular by the distance measurement unit 51 of the control device 50. In the distance measurement mode, the distance measurement unit 51 sends a command signal to the driver circuit 16 via the signal line 18. In response to the command signal, the driver circuit 16 generates an activation signal for the piezoelectric element 12 and outputs it to the piezoelectric element 12 through the first contact pin 13 and the thin loose wire 15. The activation signal causes the piezoelectric element 12 to excite the ultrasonic diaphragm 10 to vibrate, whereby the ultrasonic signal is emitted in the axial direction 19 to the environment of the motor vehicle 80. If the ultrasonic signal encounters an obstacle in the environment of the motor vehicle 80, it can be reflected from the obstacle back to the ultrasonic diaphragm 10, which causes vibration. The vibration of the ultrasonic diaphragm 10 is detected by the piezoelectric element 12, which outputs an electrical reception signal representing the vibration of the ultrasonic diaphragm 10 to the driver circuit 16 through the thin loose wire 15 and the first contact pin 13. The driver circuit 16 amplifies the electrical reception signal and transmits the amplified electrical reception signal to the distance measurement unit 51 of the control device 50 via the second contact pin 17 and the signal line 18. The distance measurement unit 50 can then determine the distance to an obstacle in the environment of the motor vehicle 80 by means of the propagation time difference between the emission of the ultrasonic signal (command signal) and the reception of the reflected ultrasonic signal (amplified electrical reception signal).

[0081] This distance measurement mode of the ultrasonic sensor 1 is influenced by a number of operating parameters. In particular, these are the operating frequency at which the ultrasonic diaphragm 10 is excited to vibrate, the amplitude of the excitation signal of the piezoelectric element 12 (which is related to the amplitude of the transmitted ultrasonic signal) and the gain at which the driver circuit 16 amplifies the electrical reception signal.

[0082] The ultrasonic sensor 1 is precalibrated during manufacture. Here and hereinafter, calibration is understood to mean the setting or adjustment of operating parameters of the ultrasonic sensor 1. Here, the operating parameters can be stored, for example, in the distance measuring unit 51 and can be used to form the command signals and / or can be transmitted to the driver circuit 16 together with each command signal. Alternatively, however, the operating parameters can also be stored directly in the driver circuit 16 and can be set directly there during calibration.

[0083] One purpose of calibrating the ultrasonic sensor 1 is to operate the ultrasonic sensor 1 at or as close as possible to the resonant frequency of the vibration system comprising the ultrasonic diaphragm 10 and the piezoelectric element 12 attached thereto, because the conversion efficiency of the system is optimal at the resonant frequency. The amplitude of the activation signal and the gain of the received signal are then set, for example, experimentally by laboratory studies in a standardized environment, so as to obtain a desired signal-to-noise ratio for the amplified received signal.

[0084] For example, a coating layer 26 with a thickness of 100 μm to 140 μm changes the mass and stiffness of the ultrasonic diaphragm 10. When the ultrasonic diaphragm 10 is sprayed, the resonant frequency of the ultrasonic diaphragm 10 also changes accordingly. Therefore, the coating layer 26 has conventionally been applied in the factory of the supplier manufacturing the ultrasonic sensor 100, and the above calibration has been performed on the already sprayed ultrasonic sensor 100 in the supplier's factory.

[0085] However, it is conceivable that the coating layer 26 is only applied to the ultrasonic diaphragm 10 of the unsprayed ultrasonic sensor 1 in the aftermarket. It is also conceivable that the already sprayed ultrasonic sensor 100 is sprayed again, for example if a used motor vehicle 80 is repainted. In these cases, the performance of the conventional ultrasonic sensor deteriorates in each case.

[0086] According to an exemplary embodiment, it is therefore proposed to provide the control device 50 with functions ( Figure 4 in 52 - 54) which enable the operating parameters of the ultrasonic sensors 1, 100 to be dynamically recalibrated during the normal operation of the motor vehicle 80, i.e. when the customer owns the motor vehicle 80.

[0087] Figure 4 Function units 51 - 54 of a control device 50 according to an exemplary embodiment are schematically shown. Figure 5 Steps of a method for operating ultrasonic sensors 1, 100 ( Figure 1 、 3 ) according to an exemplary embodiment are shown.

[0088] In addition to the above - mentioned distance - measuring unit 51, the control device 50 of the exemplary embodiment further includes a characteristic - determining unit 52 (an example of a "first unit"), an evaluation unit 53, and a calibration unit 54.

[0089] In step S1 of the method, the characteristic - determining unit 52 determines the sensor characteristics of the ultrasonic sensors 1, 100 ( Figure 1 、 Figure 3 ).

[0090] To clearly show that the sensor characteristics can be determined during the normal operation of the motor vehicle, it should first be noted that the ultrasonic diaphragm 10 ( Figure 2 ) with the piezoelectric element 12 ( Figure 2 ) attached thereto and the driver circuit 16 ( Figure 2 ) can each be regarded as components of an electromechanical system.

[0091] Figure 6 A schematic equivalent circuit diagram of the electromechanical system of the ultrasonic sensors 1, 100 is shown. Refer to Figure 1-3and Figure 6 The electromechanical system can be regarded as a parallel resonant circuit having a resistor 21, an inductor 22 and a capacitor 23. The resonant frequency of the parallel resonant circuit corresponds here to the natural frequency of the ultrasonic diaphragm 10, i.e. the frequency at which the ultrasonic diaphragm 10 transmits ultrasonic signals particularly effectively, or the frequency at which the conversion efficiency of the system comprising the ultrasonic diaphragm 10 and the piezoelectric element 12 is maximum. In other words, the power dissipation on the resistor 21 corresponds to the energy emission in the form of ultrasonic waves, while the inductor 22 and the capacitor 23 correspond to the flexibility and mass of the ultrasonic diaphragm 10 which affect the conversion efficiency.

[0092] It is thus clear that a pure electrical characterization of the ultrasonic sensors 1, 100 is possible, which does not depend on the presence of defined laboratory conditions in the environment of the motor vehicle 80.

[0093] Thus, the sensor characteristics determined in step S1 are in particular a function of an analytical or numerical representation determined by measuring the electromechanical systems 10, 12, 16 of the ultrasonic sensors 1, 100, and which describes the response behavior of the electromechanical systems 10, 12, 16 of the ultrasonic sensors 1, 100.

[0094] It should be emphasized again that step S1 is not carried out in the factory of the supplier company, but during the normal operation of the motor vehicle 80. For example, step S1 can be carried out in response to the start of the ignition device of the motor vehicle 80 or at regular intervals.

[0095] Further reference Figure 1 、 Figure 3 、 Figure 4 and Figure 5 In step S2 following step S1, the second unit evaluates the sensor characteristics determined in step S1 in order to determine whether at least one operating parameter of the ultrasonic sensors 1, 100 is to be adjusted. In other words, it is evaluated whether the conversion efficiency of the ultrasonic sensors 1, 100 can be increased by adapting the operating parameters to the determined sensor characteristics.

[0096] If it is determined in step S2 that at least one operating parameter is to be adjusted, then in step S3 the calibration unit 55 adjusts the operating parameter based on the determined sensor characteristics. For example, the operating frequency of the ultrasonic sensor 100 can be changed. If this is not possible or not desired, for example due to technical limitations, the amplitude of the activation signal and / or the gain of the received signal can also be increased. In the present exemplary embodiment, the adjusted operating parameter is stored in the distance measurement unit 51 of the control device 50 and is from then on implemented by the distance measurement unit 51 in subsequent distance measurements with the ultrasonic sensors 1, 100.

[0097] Thus, the control device 50 of the exemplary embodiment may advantageously provide for dynamic recalibration of operating parameters of the ultrasonic sensor 1 , 100 if the sensor characteristics of the ultrasonic sensor 1 , 100 change, for example due to a subsequent application of a paint layer 26 or another paint layer.

[0098] This enables, for example, an automotive supplier to deliver an unpainted ultrasonic sensor 1 which is only subsequently (after the end of the production line) painted, for example by an automotive manufacturer in the production of new vehicles or by a repair shop in the case where a defective ultrasonic sensor 100 is subsequently replaced by an unpainted aftermarket ultrasonic sensor 1. An automotive supplier company can thus achieve an advantageous simplification of production, whereby unpainted ultrasonic sensors 1 can be produced and delivered not only as OEM parts for new vehicle production but also as aftermarket parts for service. The unpainted ultrasonic sensor 1 can in particular be supplied complete with a control device 50 according to an exemplary embodiment, which ensures automatic recalibration of the operating parameters of the ultrasonic sensor 1 when the ultrasonic sensor 1 is first painted or repainted later in its life. This further enables automotive manufacturers to produce small series with special paint in small batches, where supply-side painting is commercially impossible. Customers can repaint their vehicles in different colors without adversely affecting the performance of the likewise painted ultrasonic sensor 100.

[0099] Advantageous developments of the exemplary embodiment will now be described.

[0100] refer to Figures 1 to 5 A first advantageous development is described. According to a first advantageous development, the sensor characteristic determined by the characteristic determination unit 52 in step S1 is a transfer function of the electromechanical components (ultrasonic membrane 9 with piezoelectric element 12 attached thereto and driver circuit 16) of the ultrasonic sensor 1, 100. The characteristic determination unit 52 applies a voltage signal U(t) as a test signal to the ultrasonic sensor 1, 100 in order to determine the transfer function, and measures the current response I(t) of the ultrasonic sensor 1, 100 to the voltage signal U(t) in order to determine the transfer function.

[0101] In particular, the test voltage signal U(t) can preferably include a plurality of signal components with different frequencies. The test voltage signal U(t) can particularly preferably be a pulse-shaped impulse excitation. The test voltage signal U(t) and the current response signal I(t) are then converted into the frequency domain by Fourier or Laplace transformation and divided by one another to obtain the transfer function. However, instead of a pulse-shaped impulse excitation, different frequencies f n Continuously apply multiple, for example, sinusoidal test voltage signals U n (t), and the corresponding current response signal I can be captured n(t). In this case, the measurement points can also be constructed in the frequency domain, and the transfer function can be obtained by dividing the curve fitted to the measurement points in the frequency domain.

[0102] Thus, a purely electrical characterization of the ultrasonic sensor 1, 100 can advantageously be performed. The resonant frequency and the frequency-dependent conversion efficiency of the ultrasonic membrane 10 of the ultrasonic sensor 1, 100 can advantageously be derived from the determined transmission function (an example of a signal characteristic). It can therefore be used as a basis for determining suitable operating parameters of the ultrasonic sensor 1, 100, which can then be implemented (adjusted) accordingly by the third unit in step S3.

[0103] Figure 7 A flow chart illustrating the processing of the evaluation unit 53 of a further advantageous development of the exemplary embodiment is shown. In other words, Figure 7 Shows Figure 5 Advantageous details of the design of step S2 in .

[0104] refer to Figure 1 , Figure 3 , Figure 4 and Figure 7 A second advantageous development is described. In step S21, in a decision block S211 according to the second advantageous development, the evaluation unit 53 first evaluates the need (requirement) for an adjustment of the operating parameters of the ultrasonic sensor 1, 100. To this end, for example, the evaluation unit 53 compares sensor characteristics which are stored in a storage area of ​​the evaluation unit 53 and which correspond to the currently set operating parameters of the ultrasonic sensor 1, 100 with the sensor characteristics determined in step S1. The evaluation unit 53 determines, for example, a similarity parameter which indicates a deviation between the sensor characteristics. The similarity parameter can be, for example, a correlation coefficient or an integral of the differences in the sensor characteristics. If the deviation indicated by the similarity parameter between the stored sensor characteristics and the determined sensor characteristics is greater than a predefined threshold value, the evaluation unit 53 determines that an adjustment of the operating parameters of the ultrasonic sensor 100 is necessary ( Figure 7 Otherwise, the evaluation unit 53 determines that no adjustment is required ( Figure 7 N at S211 in the process), and the method ends. Therefore, unnecessary frequent recalibration can be avoided. Otherwise ( Figure 7 Y at S211 in the process), the method continues with step S22.

[0105] In step S22, the evaluation unit 53 evaluates the convenience of adjusting the operating parameters of the ultrasonic sensor 1, 100. If it is evaluated in step S22 that the deviation identified in step S21 is due to the paint coating of the ultrasonic sensor 100 (the application of the paint layer 26 or the addition of an additional further paint layer to the outer surface 11 of the ultrasonic diaphragm 10), the adjustment is considered to be particularly advantageous. The details of the decision on whether the deviation is caused by the paint coating will be discussed below with reference to a number of further advantageous developments.

[0106] refer to Figure 3 , Figure 4 and Figure 7 . According to a third advantageous embodiment, the evaluation unit 53 first performs a decision box S221 in step. In decision box S221, the evaluation unit 53 checks whether the deviation identified in step S21 (i.e. the similarity parameter) is smaller than a second predefined threshold value, which is greater than a (first) predefined threshold value smaller than the similarity parameter. This means that the evaluation unit 53 checks whether the similarity parameter is between the first and second threshold values. If not, i.e. if the similarity parameter also exceeds the second threshold value, the method ends (N at S221). In this case, it is assumed that the deviation is so large that it is not due to a paint coating on the ultrasonic diaphragm 10, but to another fault condition caused by, for example, dust or ice. Otherwise (Y at S221), the method continues to decision box S222.

[0107] Furthermore, according to a particularly preferred optional design of the third development, only when the motor vehicle 80 ( Figure 3 ), the method further branches to "Yes" in decision block S221. Otherwise, even if the deviation is above the first threshold and below the second threshold, the method branches to "N" and the method ends. In other words, the suitability of recalibration is identified only if the deviation is not excessive and remains stable for a period of time.

[0108] refer to Figure 1 , Figure 3 , Figure 4 and Figure 7. According to a fourth advantageous development, the evaluation unit 53 also performs a decision block S222 in step S22. In the decision block S222, the evaluation unit 53 causes the distance measuring unit 51 to perform distance measurements using the ultrasonic sensor 1, 100 and a plurality of further ultrasonic sensors (not shown) of the motor vehicle 80. If it is determined that the distance measurements performed with different ultrasonic sensors 1, 100 or with the same ultrasonic sensor 1, 100 at time intervals differ significantly from one another and do not show a consistent image of the environment of the motor vehicle 80, and / or if the distance measurements performed with the ultrasonic sensor 1, 100 indicate that there is an obstacle in the immediate vicinity of the ultrasonic sensor 100, the evaluation unit 53 evaluates that it is currently inappropriate to adjust the operating parameters of the ultrasonic sensor 100 based on the determined characteristics (no in the decision block S222), because the modified sensor characteristics of the ultrasonic sensor 100 may be due to temporary damage, such as dust or ice on the ultrasonic diaphragm 10, or different obstacles in the vicinity of the ultrasonic sensor 1, 100, and the method ends. Otherwise (Y at S221), either the convenience of adaptation can be identified, or as Figure 7 As shown, the method continues to decision block S223.

[0109] Figure 8 An evaluation unit 53 according to a fifth advantageous development is shown. Figure 1 , Figure 3 and Figure 8 The lookup table 55 is stored in the evaluation unit 53 of the fifth development. A plurality of predefined sensor characteristics 56 and a plurality of sets of operating parameter values ​​57 are stored in the lookup table 55. A corresponding data set 58 in the lookup table comprises one of the sensor characteristics 56 and a relevant set of the plurality of sets of operating parameter values ​​57, respectively. The data set 58 is created by the supplier and saved in the lookup table 55. The data set 58 is measured by calibration measurements performed in a laboratory environment using corresponding measuring equipment with different configurations of the ultrasonic sensor 1, 100. For example, the first data set 581 may include calibration measurements of the ultrasonic sensor 1 ( Figure 1 ) on the sensor characteristics 561 and by using an unsprayed ultrasonic sensor 1 ( Figure 1) on a corresponding laboratory device on a ) and determined as the best related operating parameters 571. A second data set 582 in the data set 58 may include the sensor characteristics 562 determined on the sprayed ultrasonic sensor 100 and the related operating parameter values ​​572 determined to be the best on the sprayed ultrasonic sensor 100. Other data sets in the data set 58 may include sensor characteristics 56 determined on ultrasonic sensors 100 provided with other types of paint or multiple paint layers 26 and the related operating parameter values ​​57 determined to be the best. In this way, an automotive supplier can measure many expected scenarios with different expected paint concentrations and numbers of paint layers 26 in the laboratory, and can store the resulting information related to the sensor characteristics 56 and the related optimal operating value set 57 in the lookup table 55 of the evaluation unit 53.

[0110] refer to Figure 1 , Figure 3 , Figure 7 and Figure 8 According to a fifth development, the evaluation unit 53 also performs a decision block S223 in step S22 in order to evaluate whether the deviation detected in step S21 is due to the paint coating. In the decision block S223, the evaluation unit 53 will Figure 5 ) is compared with each sensor characteristic 56 stored in the lookup table 53. In the same manner as in decision block S21, a deviation between the sensor characteristic defined in step S1 and the corresponding sensor characteristic 56 from the lookup table 55 may be determined here, and a match may be identified if the deviation is less than a predefined threshold.

[0111] If a match is identified in the above comparison, the evaluation unit 53 evaluates that an adjustment of the operating parameters of the ultrasonic sensor 1, 100 is advantageous due to the change in the paint coating and must therefore be performed (Y in decision block S223). In this case, the evaluation unit 53 looks up the operating parameter value 57 associated with the matching sensor characteristic from the sensor characteristic 56 in the lookup table 55 and forwards the relevant set of operating parameters 574 to the calibration unit 54 for implementation.

[0112] If no match is identified ("N" in decision block S223), the method may end without recalibration. Alternatively, however, according to a sixth advantageous development, the evaluation unit 53 continues with decision block S224.

[0113] Fig. 9 An evaluation unit 53 according to a sixth advantageous development is shown. Figure 1 , Figure 3 and Fig. 9 A sixth advantageous development of the evaluation unit 53 comprises a model 59. The model 59 is configured to respond to the step S1 ( Figure 5) and outputs an evaluation 60 indicating whether an adjustment of the operating parameters of the ultrasonic sensor 1, 100 may be advantageous, since according to the model the determined sensor characteristic 560 is evaluated as being consistent with the ultrasonic diaphragm 10 ( Figure 1 , Figure 3 ). In addition, at least when the evaluation 60 produces a positive result, the model 59 is configured to further output an operating parameter 574 in response to the input of the determined sensor characteristic 560, which ensures that the ultrasonic sensor 1, 100 operates efficiently with the determined sensor characteristic 560.

[0114] Reference again Figure 1 , Figure 3 , Figure 7 and Fig. 9 In decision block S224, the fifth development evaluation unit 53 will in step S1 ( Figure 5 ) is input into the model 59, and it is evaluated whether the operating parameters are to be adjusted according to the evaluation 60. If yes (Y at S224), the operating parameter set 574 output by the model is provided to the calibration unit 54 for implementation. If no (N at S224), the adjustment of the operating parameters is not appropriate, and the method ends without recalibration.

[0115] In some variations, the sixth developed model 59 may be a physical model that analytically derives the evaluation 60 and a recommended set of operating parameter values ​​574. In other variations, the model 59 may be a data-based model, such as a statistical model with a plurality of adjustable parameters, or a neural network, such as a deep neural network. The parameters of the statistical model or the firing probabilities of the neurons of the deep neural network may have been appropriately trained by the vendor by training with a training data set. In particular, the training data set used may be a reference data set stored in the lookup table 55. Figure 8 The same data set 58 as described in detail for the fifth development. In other words, the data-based model 59 may have been trained using predefined sensor characteristics 56 as training input data and using relevant optimal operating parameter values ​​57 experimentally determined in a laboratory environment as training output data.

[0116] Although the invention has been described based on exemplary embodiments, it can be modified in many ways. Features that have been disclosed for different developments of the exemplary embodiments can be combined with each other and with features of the exemplary embodiments in any suitable manner and / or can be selected individually, as long as no inconsistencies arise as a result.

[0117] In particular, if you execute Figure 7The complete method shown, the evaluation unit 53 may have a look-up table 55 ( Figure 8 ) and Model 59 ( Fig. 9 ). However, the lookup table 55 and the associated decision block S223 may also be omitted. This applies in particular if there is a decision block S224 with a model-based evaluation, although this is again optional. The evaluation of the convenience of adjusting the operating parameters based on a plurality of environmental measurements (decision block S222) and the evaluation of the necessity and / or convenience based on a comparison with stored sensor characteristics (decision blocks S211, S221) are also optional features, respectively.

[0118] Various further developments describe that the operating parameter value 574 to which the operating parameter of the calibration unit 54 is to be adjusted is obtained from the look-up table 55 and / or is determined by the model 59. However, it is also conceivable that the operating parameter 574 to which the operating parameter of the ultrasonic sensor 1, 100 is to be adjusted is derived directly from the sensor characteristic 560 defined in step S1. For example, if the sensor characteristic 560 is a transmission function, the operating frequency of the ultrasonic sensor 1, 100 can, for example, be adapted to the frequency at which the transmission function has a maximum value (resonance frequency). However, if it is decided to keep the operating frequency at a different frequency, the amplitude of the activation signal and / or the gain of the received signal can be selected as a function of the ratio of the transmission function value at different frequencies to the maximum transmission function value, thereby compensating for the reduced conversion efficiency due to the shifted position of the operating frequency by amplification.

[0119] According to the exemplary embodiment, the characteristic determination unit 52 (first unit 52), the evaluation unit 53 (second unit 53) and the calibration unit 54 (third unit 54) are integrated into a common control device 50 together with the functionality of the distance measuring unit 51. However, it is also conceivable that the characteristic determination unit 52 (first unit 52), the evaluation unit 53 (second unit 53) and the calibration unit 54 (third unit 54) are arranged in a separate control device, which, when installed in the motor vehicle 80, has a communication connection via the signal line 18 to the distance measuring control device containing the distance measuring unit 51. Therefore, the distance measuring unit 51 is not an essential feature of the proposed control device 50. It is also conceivable that the functionality of the characteristic determination unit 52 (first unit 52), the evaluation unit 53 (second unit 53) and the calibration unit 54 (third unit 54) are integrated into the ultrasonic sensor 1, 100, so that the ultrasonic sensor 1, 100 can also be an ultrasonic sensor 1, 100 with an integrated control device 52-54.

[0120] Reference numerals list

[0121] 1 Ultrasonic sensor

[0122] 2 Plastic housing

[0123] 3 Shell body

[0124] 4 Retaining ring

[0125] 5. Cover

[0126] 6 Extended section

[0127] 7 Edge of the housing body

[0128] 8 Opening in housing body

[0129] 9 Diaphragm tank

[0130] 10 Ultrasonic diaphragm

[0131] 11 Outer surface of ultrasonic diaphragm

[0132] 12 Piezoelectric element

[0133] 13 First contact pin

[0134] 14. Printed Circuit Board

[0135] 15 Thin loose lines

[0136] 16 Driver Circuit

[0137] 17 Second contact pin

[0138] 18 Signal Line

[0139] 19 Axial direction

[0140] 20 Equivalent circuit diagram

[0141] 21 Resistors

[0142] 22 Inductor

[0143] 23 Capacitor

[0144] 24 Front fender

[0145] 25 Opening in front fender

[0146] 26 coating layers

[0147] 50 Control device

[0148] 51 Distance measurement unit

[0149] 52 Characteristic determination unit

[0150] 53 evaluation units

[0151] 54 Calibration Units

[0152] 55 Lookup Table

[0153] 56 predefined sensor characteristics

[0154] 57 Related operating parameters

[0155] 58 Datasets

[0156] 59 Model

[0157] 60 Evaluation

[0158] 80 Motor Vehicles

[0159] 100 Ultrasonic Sensors

[0160] 560 Determined sensor characteristics

[0161] 561-562 Predefined sensor characteristics

[0162] 571-572 Related operation parameter values

[0163] 574 The operating parameter value to which the operating parameter is to be adjusted

[0164] 581-582 Dataset

[0165] S1-S3 Method Steps

[0166] S21, S22 Method steps, sub-steps of step S2

[0167] S211 judgment box

[0168] S221-S224 judgment box

Claims

1. A control device (50) for an ultrasonic sensor (1, 100) for a motor vehicle (80), the control device (50) include: a first unit (52) configured to determine sensor characteristics of the ultrasonic sensor (1, 100) during regular operation of the motor vehicle (80); a second unit (53) configured to evaluate the determined sensor characteristic in order to determine whether an operating parameter of the ultrasonic sensor (1, 100) needs to be adjusted; as well as A third unit (54) is configured to adjust the operating parameter of the ultrasonic sensor (1, 100) based on the determined sensor characteristic if the second unit (53) evaluates that the operating parameter is to be adjusted.

2. The control device according to claim 1, It is characterized in that The evaluation performed by the second unit (53) comprises determining a deviation of the determined sensor characteristic from a sensor characteristic stored in the second unit (53) corresponding to a current operating parameter value of the ultrasonic sensor (1, 100).

3. The control device according to claim 2, It is characterized in that The evaluation performed by the second unit (53) includes evaluating whether an identified deviation of the determined sensor characteristic from the stored sensor characteristic is due to a paint coating of the ultrasonic diaphragm (10) of the ultrasonic sensor (1, 100), and adjusting the operating parameter only if the identified deviation is due to the paint coating of the ultrasonic diaphragm (10).

4. A control device according to any one of the preceding claims, It is characterized in that The second unit (53) is configured to evaluate whether the operating parameter is to be adjusted by comparing a first distance measurement performed with the ultrasonic sensor (1, 100) with a second distance measurement performed with the same or another ultrasonic sensor (1, 100).

5. A control device as claimed in any one of the preceding claims, It is characterized in that The second unit (53) stores a lookup table (55) containing a plurality of predefined sensor characteristics (56) and associated operating parameter values ​​(57), the associated operating parameter values ​​(57) being predetermined by measuring ultrasonic sensors (1, 100) of different sprays under laboratory conditions, and The second unit (53) is configured to evaluate whether the operating parameter is to be adjusted by comparing the determined sensor characteristic (560) with the plurality of predefined sensor characteristics (56), and / or to determine an operating parameter value (574) to which the third unit (54) is to adjust the operating parameter by referring to the lookup table (55).

6. A control device as claimed in any one of the preceding claims, It is characterized in that The second unit (53) includes a physical or data-based model (59) configured to output an assessment (60) of whether an operating parameter is to be adjusted based on a sensor characteristic (560) input into the model (59), and / or to output an operating parameter (574) value to which the operating parameter is to be adjusted, and The second unit (53) is configured to input the determined sensor characteristic (560) into the physical or data-based model (59) and to use the physical or data-based model (59) to evaluate whether to adjust the operating parameter and / or to determine an operating parameter (574) to which the third unit (54) is to adjust the operating parameter.

7. The control device according to claim 6, It is characterized in that The data-based model (59) includes one or more trained neural networks.

8. A control device as claimed in any one of the preceding claims, It is characterized in that The corresponding sensor characteristic determined by the first unit (52) is a transfer function of an electromechanical component (9, 10, 12, 16) of the ultrasonic sensor (1, 100), and the first unit (52) is configured to apply an electrical test signal to the ultrasonic sensor (1, 100) and to capture an electrical response signal from the ultrasonic sensor (1, 100) in order to determine the sensor characteristic.

9. A control device as claimed in any one of the preceding claims, It is characterized in that The operating parameters adjusted by the third unit (54) include one or more of the following parameters: an operating frequency at which the ultrasonic diaphragm (10) of the ultrasonic sensor (1, 100) is excited to generate vibrations, an amplitude of an activation signal used by a driver circuit (16) of the ultrasonic sensor (1, 100) to activate the acoustic transducer element (12) of the ultrasonic sensor (1, 100), and an amplification factor at which a received signal output by the acoustic transducer element (12) to the driver circuit (16) is amplified.

10. A method for operating an ultrasonic sensor (1, 100) of a motor vehicle (80), include: determining (S1) a sensor characteristic of the ultrasonic sensor (1, 100) during regular operation of the motor vehicle (80); evaluating (S2) the determined sensor characteristics in order to determine whether an operating parameter of the ultrasonic sensor (1, 100) is to be adjusted; as well as If it has been assessed that the operating parameter is to be adjusted, the operating parameter of the ultrasonic sensor (1, 100) is adjusted (S3) based on the determined sensor characteristic.

11. A computer program product comprising instructions which, when executed by a control unit (50) of a motor vehicle (80), cause the control unit (50) to perform a method as claimed in any one of the preceding claims.

12. An ultrasonic sensor (1, 100), comprising an ultrasonic diaphragm (10), an acoustic transducer element (20) arranged on the inner side of the ultrasonic diaphragm (10) for vibration excitation and vibration detection of the ultrasonic diaphragm (10), a driver circuit (16) for activating the acoustic transducer element (12), and a control device (52-54) as described in any one of claims 1 to 9.

13. A kit (50, 1), include: A control device (50) according to any one of claims 1 to 9 and / or a computer program product according to claim 13, and An ultrasonic sensor (1, 100) comprises an ultrasonic diaphragm (10), an acoustic transducer element (12) arranged on the inner side of the ultrasonic diaphragm (10) for vibration excitation and vibration detection of the ultrasonic diaphragm (10), and a driver circuit (16) for activating the acoustic transducer element (12).

14. The kit (50, 1) according to claim 13 or the ultrasonic sensor (1) according to claim 12, in, The ultrasonic diaphragm (10) of the ultrasonic sensor (1) has at least no final coating of paint.

15. A motor vehicle (80) having a control device (50) according to any one of claims 1 to 9, an ultrasonic sensor (1, 100) according to claim 12 or a kit (50, 1) according to claim 13 or 14.

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