Method for operating an ultrasonic sensor

Abstract

The invention relates to a method (M100, M200) for operating an ultrasonic sensor (106, 106a, 106b), comprising: providing (S108) a phase response (PG) of a response signal (Sat) of the ultrasonic sensor (106, 106a, 106b); determining (S124) a characteristic data set by means of a trained model on the basis of an input data set, the input data set containing the phase response (PG), and the characteristic data set containing a transmission gain response (VS), a reception gain response (VE) and / or a transmission-reception gain response (VSE), which corresponds to a difference between the transmission gain response (VS) and the reception gain response (VS), with respect to the ultrasonic sensor (106, 106a, 106b); specifying (S128) a setting of the ultrasonic sensor (106, 106a, 106b) on the basis of the characteristic data set.

Description

[0001] METHOD FOR OPERATING AN ULTRASOUND SENSOR

[0002] The present invention relates to a method for operating an ultrasonic sensor, a method for operating an ultrasonic sensor circuit, a computer program product, an ultrasonic sensor, an ultrasonic sensor circuit, a control unit and a vehicle.

[0003] It is known to determine the phase response of an ultrasonic sensor and to correct the transfer behavior of the ultrasonic sensor by comparing characteristic points with a reference.

[0004] German patent DE 10 2021 1 12 996 A1 describes a method for determining the functional state of an ultrasonic sensor, whereby a test signal is applied to the sensor and a response signal is detected by the ultrasonic sensor. Depending on this, a phase frequency response of the response signal is determined and compared with reference values ​​at two extreme frequencies in order to correct the phase response and thereby determine parameters of a state model of the ultrasonic sensor.

[0005] German patent DE 10 1088 042 820 A1 describes a sensor device comprising a functional monitoring device designed to determine the impedance characteristic of an ultrasonic sensor as a function of an excitation frequency. Extreme values ​​of this characteristic are comparable to extreme values ​​of a reference characteristic in order to detect contamination and aging of the ultrasonic sensor.

[0006] US Patent 1 1 163 048 B2 describes a method for operating a piezoelectric transducer. First, the phase response of the transducer is determined as a function of frequency (frequency-dependent phase response). Then, a set of characteristic values ​​for an equivalent circuit of the transducer is calculated from the offset of characteristic points of the determined phase response to characteristic points of a stored phase response. From this set of characteristic values, amplitude gains in sideband frequencies are determined, and these gains are compared. If an imbalance in the amplitude gains is detected, the transmission frequency, the signal strength at a given transmission frequency, and / or an input filter can be adjusted.

[0007] In each of the three methods mentioned above, a deviation of characteristic curve values ​​from a reference is determined. The more curve values ​​are used, the more accurately an ultrasonic sensor state can be determined, but the more computationally intensive the method becomes. The subsequent calculation of characteristic values ​​of an equivalent circuit diagram leads to a (model-dependent) accurate description of the ultrasonic sensor's state, but this too is a computationally intensive process. Therefore, precise knowledge of the ultrasonic sensor's state requires a computationally intensive method, which is correspondingly time-consuming.

[0008] It is known for the application of monitoring installation positions that an ultrasonic signal can be input into a trained model to output a characteristic value. For example, DE 10 2019 1 19 585 A1 describes a method for monitoring the installation position and / or orientation of an ultrasonic sensor, wherein a measured value corresponding to a reflected ultrasonic signal is input into an artificial neural network, whereupon the artificial neural network determines the position and orientation.

[0009] Against this background, one object of the present invention is to provide a rapidly executable method for accurately determining the state of an ultrasonic sensor.

[0010] Accordingly, a method for operating an ultrasonic sensor is proposed, which includes at least the following steps: providing a phase response of a response signal from the ultrasonic sensor; determining a characteristic curve data set by a trained model as a function of an input data set, wherein the input data set contains the phase response, and wherein the characteristic curve data set contains a transmit gain response, a receive gain response and / or a transmit-receive gain response with respect to the ultrasonic sensor, wherein the transmit-receive gain response corresponds to a difference between the transmit gain response and the receive gain response; and specifying a setting of the ultrasonic sensor as a function of the characteristic curve data set.

[0011] It can therefore be said that, according to the proposed method, the phase response is directly evaluated to at least one characteristic curve using a trained model. Compared to the method described in US 11,163,048 B2, the previously sequential steps of a) determining the offset (curve fitting), b) calculating the equivalent circuit values, and c) determining the characteristic curve(s) from the equivalent circuit are replaced by a single evaluation step using the trained model. It has been found that the proposed method can be executed faster than the method described in US 11,163,048 B2. Thus, the respective ultrasonic sensor is available for measurement operation more quickly, preferably for the precise detection of objects in the vicinity of a vehicle. One could also say that the proposed method is a method for calibrating an ultrasonic sensor.

[0012] The model can be trained, for example, with datasets obtained or acquired according to the procedure described in US 11 163 048 B2. For instance, in a training operation, a phase response can be used as the input function, and a transmit gain response, a receive gain response, and / or a transmit-receive gain response associated with that phase response can be used as the training function.

[0013] For example, the trained model might be a generic model trained for different ultrasonic sensors of one type or even several types. Alternatively, the trained model might be a partially customized model, first trained for different ultrasonic sensors of one type or even several types, and then for that specific ultrasonic sensor, for example, during its operation. Finally, the trained model might be a custom-trained model trained only for that specific ultrasonic sensor, for example, during manufacturing / commissioning and during its operation.

[0014] Ultrasound is preferably understood to mean a range of 20 kHz to 100 kHz and more preferably 40 kHz to 65 kHz.

[0015] The phase response can be understood, for example, as a time offset between an excitation signal to the ultrasonic sensor and a response signal of the ultrasonic sensor to the excitation signal, resolved into several frequencies or frequency ranges.

[0016] The excitation signal can be, for example, an electrical signal that can be measured in a line as a voltage waveform between two conductors, as a current waveform in a conductor, and / or as a digital signal. The excitation signal preferably extends over a frequency range. For example, the excitation signal is a sinusoidal oscillation with a constant amplitude and a continuously increasing frequency; this signal is technically called a "chrip."

[0017] The response signal can be understood, for example, as an electrical signal that can be measured in a line as a voltage curve between two conductors and / or as a current curve in a conductor and / or as a digital signal.

[0018] The transmit gain response can be understood, for example, as the amplitude ratio, resolved into several frequencies or frequency ranges, between an excitation signal applied to the ultrasonic sensor and an ultrasonic signal transmitted / emitted / generated by the ultrasonic sensor. The transmit gain response can also be referred to as "sound intensity exposure level" or "LPS" in technical terms. For control or calibration purposes, the transmit gain response can be determined, for example, by applying an excitation signal (such as a "chirp") to the ultrasonic sensor and measuring the ultrasonic signal using a measuring microphone with known characteristics at a defined distance, particularly under defined acoustic conditions.

[0019] An ultrasound signal can be understood as an acoustic signal. The ultrasound signal can be measured in a fluid, particularly in air. The ultrasound signal can be measured, for example, by a calibrated ultrasound measuring device and / or an acoustically adjacent ultrasound sensor.

[0020] The receive gain response can be understood, for example, as the amplitude ratio, resolved into several frequencies or frequency ranges, between an ultrasonic signal received by the ultrasonic sensor and a response signal from the ultrasonic sensor to that ultrasonic signal. The receive gain response can be referred to technically as "sensor receiving sensitivity" or "LPE." For control or calibration purposes, the receive gain response can be measured, for example, by emitting or transmitting a defined ultrasonic signal from a loudspeaker with known characteristics at a defined distance from the ultrasonic sensor and converting the ultrasonic signal into a response signal by the ultrasonic sensor. The defined ultrasonic signal could, for example, be a sinusoidal oscillation with a continuously increasing frequency and a constant amplitude.

[0021] The transmit-receive gain response can be understood, for example, as the amplitude ratio, resolved into several frequencies or frequency ranges, between an excitation signal to the ultrasonic sensor, which is converted into an ultrasonic signal by the sensor, and a response signal from the sensor to the (e.g., reflected) ultrasonic signal. The transmit-receive gain response can be interpreted, for instance, as the expected amplitude if the ultrasonic sensor is excited with a defined transmit current and transmit gain. The transmit-receive gain response can be calculated as the difference between the measured transmit and receive gain responses. In technical terms, the transmit-receive gain response can be referred to as a "subtraction value," a "subtraction value curve," and / or "SWR."

[0022] It may optionally be that providing the phase response includes: applying an excitation signal to a signal line of the ultrasonic sensor, wherein the signal power for obtaining the phase response is up to 50%, preferably up to 30%, and more preferably up to 20% of a signal power suitable for object detection, and wherein the frequency of the excitation signal is changed, in particular in steps or continuously; measuring, in particular continuously, a line signal of the signal line during the excitation; and determining the response signal as a function of the line signal and the excitation signal. It is therefore proposed to apply a weak test excitation to the ultrasonic sensor, which does not result in a usable ultrasonic signal, but which elicits a response from the sensor device that is measurable in the signal line.With a typical ultrasound signal, the excitation is so much stronger than the resulting transmission signal that a measuring device intended for measuring the transmission signal during and shortly after the excitation would not produce a usable measurement signal. In this case, however, such a weak excitation is generated and applied that the measurement signal is continuously recorded and available for evaluation. In this way, the response signal can be extracted from the measurement signal, or transmission signal, with high accuracy.

[0023] Optionally, providing the phase response may include: generating a known ultrasonic signal using another ultrasonic generator, whereby the frequency of the ultrasonic signal is changed (stepwise or continuously); measuring the line signal (a line signal from the ultrasonic sensor's signal line); and determining the response signal as a function of the line signal and the known ultrasonic signal. This option is particularly suitable for use in the final assembly or quality control of an ultrasonic sensor, or at any time in an ultrasonic sensor circuit consisting of at least two acoustically adjacent ultrasonic sensors.

[0024] Acoustically adjacent ultrasonic sensors can be understood as an arrangement in which the ultrasonic sensors can each receive an ultrasonic signal from each other.

[0025] The phase response is a type of information contained in the input data set. Optionally, the input data set may also contain at least the following type of information: a provided amplitude response of the response signal. The amplitude response is preferably provided in the same way as the phase response. The amplitude response can be understood, for example, as the amplitude ratio, resolved across several frequencies or frequency ranges, between an excitation signal to the ultrasonic sensor and a response signal from the ultrasonic sensor to the excitation signal. Knowledge of the amplitude response can lead to more precise characteristic curves in the characteristic curve data set.

[0026] Optionally, the input data set may also contain at least the following type of information: the excitation signal to the ultrasonic sensor, which is preferably the excitation signal used to determine the phase response and, if applicable, the amplitude response. Knowing the excitation signal can lead to more precise characteristic curves in the characteristic curve data set.

[0027] It may be optional for the input data set to additionally contain at least the following type of information: the ultrasound signal that may be generated in response to the excitation signal and / or in response to which the response signal may be generated.

[0028] Knowing the ultrasound signal can lead to more precise characteristic curves in the characteristic curve dataset. Optionally, the input dataset may also contain at least the following type of information: the measured conduction signal, which includes the excitation signal and / or the response signal and / or a superposition of the excitation and response signals. Knowing the conduction signal can lead to more precise characteristic curves in the characteristic curve dataset.

[0029] Optionally, the input data set may also contain at least the following type of information: a set of parameters determined during the commissioning of the ultrasonic sensor for a (virtual) equivalent circuit describing the ultrasonic sensor (during commissioning). These parameters may be collectively referred to as "equivalent circuit diagram," "equivalent circuit diagram parameters," "ESB," and / or "ESB parameters," or similar terms. Knowledge of the parameter set can lead to more precise characteristic curves in the characteristic curve data set.

[0030] Optionally, the input data set may also contain at least the following type of information: an indicator for the age of the ultrasonic sensor and / or for the operating time accumulated by the ultrasonic sensor. The indicator for the age of the ultrasonic sensor could be, for example, the manufacturing date of the ultrasonic sensor, the installation date of the ultrasonic sensor, the manufacturing date of a vehicle carrying the ultrasonic sensor, and / or the value of a regularly incrementing counter. The indicator for the operating time accumulated by the ultrasonic sensor could be, for example, the value of a counter that is regularly incremented during the transmitting and / or receiving operation of the ultrasonic sensor, a counter that counts transmitted ultrasonic signals, or the like. Knowing the age indicator and / or the operating time indicator can lead to more precise characteristic curves in the characteristic curve data set.

[0031] Preferably, each input data set contains the same types of information. Preferably, the model is trained on the types of information in the input data set. Optionally, the method may include: providing the temperature of the ultrasonic sensor; wherein the input data set additionally contains at least the provided temperature. The temperature of the ultrasonic sensor is another type of information. The temperature of the ultrasonic sensor typically influences its ultrasonic transmission characteristics. For example, in a diaphragm-type ultrasonic sensor, the temperature typically affects the diaphragm's stiffness and thus its efficiency. Furthermore, the temperature can serve as a measure of the speed of sound in air (for example, air density is a temperature-dependent quantity). The temperature of the ultrasonic sensor can, for example, be provided as a measured ambient air temperature.The temperature of the ultrasonic sensor can be provided with higher accuracy than a measured circuit temperature of an electrical circuit within the ultrasonic sensor. The temperature of the ultrasonic sensor can be provided with even greater accuracy than a calculated membrane temperature, which is determined based on the ambient air temperature, the circuit temperature, and / or measured solar radiation. Solar radiation can, for example, be provided as a brightness measurement. Preferably, the temperature of the ultrasonic sensor is provided as a membrane temperature calculated based on the ambient air temperature and the circuit temperature.

[0032] Optionally, the model can be trained to output an assessment indicator, in addition to the characteristic curve data set, based on the same input data set. This assessment indicator serves as an indicator of whether the ultrasonic sensor's state meets an operating specification. The proposed method further includes the step of issuing a warning to the user if the trained model, based on the input data set, outputs an assessment indicator that suggests the ultrasonic sensor's state does not meet the operating specification. Thus, the trained model can detect, for example, if an ultrasonic sensor can no longer reliably detect an environmental object. This option therefore increases the operational reliability of a vehicle equipped with the ultrasonic sensor unit.Optionally, the procedure can include the following steps: providing a criteria dataset; assessing, based on the determined characteristic curve dataset and the criteria dataset, whether the ultrasonic sensor's state meets an operating specification; and issuing a warning to a user if the assessment, based on the criteria dataset and the characteristic curve dataset, indicates that the ultrasonic sensor's state does not meet the operating specification. With this option, the trained model "only" generates the characteristic curve dataset and detects, by comparing it with the criteria dataset, if, for example, an ultrasonic sensor can no longer reliably detect an environmental object. This option also increases the operational reliability of a vehicle equipped with the ultrasonic sensor unit.

[0033] The two options mentioned above for detecting whether the ultrasonic sensor is (still) compliant with specifications can be used alternatively (especially with regard to the same specification) or cumulatively (especially with regard to different specifications).

[0034] It is optional that the time interval between two executions of the procedure is preferably longer than 5 minutes and preferably shorter than 30 minutes. In other words, the procedure may include the step of performing the other / subsequent steps if more than a predetermined time has elapsed since the last execution of the procedure, where the predetermined time is preferably more than 5 minutes and / or preferably less than 30 minutes. In this way, the procedure can automatically ensure that the settings of the ultrasonic sensor are regularly checked and adjusted if necessary.

[0035] It is optional to execute the following steps of the procedure if the temperature of the ultrasonic device has changed by more than a threshold value since the last execution of the procedure, where the threshold value corresponds in particular to a temperature difference of 2 to 8 °C and preferably to 4 to 6 °C. Such a temperature change can occur, for example, when entering or exiting a tunnel or parking garage. Such a temperature change can also occur, for example, as a result of changing direction of travel from one approximately constant direction to another, such as when changing highways. This ensures that the settings of the ultrasonic sensor are monitored and adjusted depending on the situation.

[0036] It is optional that the following steps of the procedure are executed when the speed of a vehicle carrying the ultrasonic sensor falls below a threshold speed, where the threshold speed is preferably 25 to 50 km / h, preferably 35 km / h. Ultrasonic sensors are frequently used for low-speed maneuvering. For example, it may be provided that the ultrasonic sensor is only activated for object detection below the threshold speed. This option ensures that the settings are checked and adjusted when the ultrasonic sensor is activated.

[0037] Specifying a setting for the ultrasonic sensor can include, for example, adjusting or changing the setting, keeping the setting constant, activating the setting and / or deactivating the setting.

[0038] A predefined setting could be, for example, the frequency of an emitted ultrasound signal. The ultrasound frequency can be specified, for instance, as a tuning frequency and / or as the frequency of the excitation signal (suitable for generating an ultrasound signal, particularly for object detection).

[0039] A predefined setting could be, for example, the amplitude of an emitted ultrasound signal. The amplitude could be a constant value across the entire signal or a value that varies over the duration of the emission. For example, the emitted ultrasound signal could be a "chirp" (so), with the volume adjusted according to frequency. Another predefined setting could be a filter parameter for input signal amplification, for example, to compensate for (too) low transmission power at certain frequencies during processing.

[0040] A predefinable setting can, for example, be a phase response of a filter of an input amplifier to compensate for a frequency deviation of the phase responses when emitting and / or receiving the ultrasound signal, in order, for example, to determine a correct relative speed to an object in the vicinity of the vehicle from a frequency shift between the transmitted ultrasound signal and the received ultrasound signal using Doppler effect evaluation.

[0041] Another aspect of the invention relates to the application of the above-described method steps in a method for operating an ultrasonic sensor circuit containing at least two acoustically adjacent ultrasonic sensors. This method comprises: performing the steps of the above method for operating an ultrasonic sensor up to and including the step(s) of determining the characteristic curve data set for each of the ultrasonic sensors; determining two ultrasonic frequencies that have a defined frequency separation from each other, depending on the determined characteristic curve data sets; and specifying a respective transmission frequency for each of the ultrasonic sensors to one of the two determined ultrasonic frequencies. Optionally, one or more further settings can be adjusted.

[0042] Using the basic version of the above procedure for operating an ultrasonic sensor as an example, this procedure for operating an ultrasonic sensor circuit is listed in detail. For example, the ultrasonic sensor circuit has a first ultrasonic sensor and a second ultrasonic sensor. For example, a generic trained model is used.The procedure includes, for example, the following steps: providing a phase response of a response signal from the first ultrasonic sensor; determining a characteristic curve data set for the first ultrasonic sensor by the trained model as a function of an input data set, wherein the input data set contains the phase response of the first ultrasonic sensor; providing a phase response of a response signal from the second ultrasonic sensor; determining a characteristic curve data set for the second ultrasonic sensor by the trained model as a function of an input data set, wherein the input data set contains the phase response of the second ultrasonic sensor; determining two ultrasonic frequencies that have a defined frequency separation from each other as a function of the determined characteristic curve data sets; and specifying a respective transmission frequency for each of the ultrasonic sensors to one of the two determined ultrasonic frequencies.If necessary, one or more additional settings can be adjusted.

[0043] Furthermore, a computer program product is proposed which includes instructions that, when executed by a computer, cause it to execute the aforementioned method for operating an ultrasonic sensor and / or the aforementioned method for operating an ultrasonic sensor circuit. The computer program product thus possesses the features and advantages of the respective method. The computer program product is preferably designed for execution by a vehicle control unit.

[0044] A computer program product, such as a computer program tool, can be provided or delivered from a server on a network, for example, as a storage medium such as a memory card, USB stick, CD-ROM, DVD, or as a downloadable file. This can be done, for example, in a wireless communication network by transmitting the corresponding file containing the computer program product or tool.

[0045] Another aspect of the invention relates to an ultrasonic sensor configured for operation using the proposed method for operating an ultrasonic sensor. The ultrasonic sensor comprises, for example, an ultrasonic transducer and a circuit connected to the transducer, as well as a housing that preferably encloses the ultrasonic transducer completely or partially and the circuit preferably completely or partially. For example, a membrane coupled to and / or formed integrally with the ultrasonic transducer can be configured as a housing wall. The ultrasonic sensor possesses the features and advantages of the respective method.

[0046] Another aspect of the invention relates to an ultrasonic sensor circuit comprising at least two acoustically adjacent ultrasonic sensors, wherein the ultrasonic sensor circuit is configured for operation by means of the proposed method for operating an ultrasonic sensor circuit. The ultrasonic sensor circuit has the features and advantages of the respective method.

[0047] Another aspect of the invention relates to a control unit or control device for controlling an ultrasonic sensor or, preferably, an ultrasonic sensor circuit. The control device is configured to carry out the proposed method for operating an ultrasonic sensor and / or for carrying out the proposed method for operating an ultrasonic sensor circuit. The control device can, for example, have one or more line connections, each configured to output an excitation signal to one or more ultrasonic sensors and to input a response signal from one or more ultrasonic sensors. The control device has the features and advantages of the respective method.

[0048] Another aspect of the invention relates to a vehicle with a proposed ultrasonic sensor and / or a proposed ultrasonic sensor circuit and / or a proposed control device. The ultrasonic sensor(s) is / are arranged, for example, to detect an object in the vicinity of the vehicle, as well as a distance and preferably a direction to the object. The vehicle has the features and advantages of the respective ultrasonic sensor and / or the respective ultrasonic sensor circuit and / or the control device. The vehicle is, for example, a passenger car or a truck. The vehicle preferably comprises a number of further sensor units that are configured to detect the vehicle's driving state and to detect the vehicle's surroundings. Examples of such sensor units of the vehicle are image acquisition devices, such as a camera, a radar (e.g., radar ...Radio detection and ranging (RDS) or lidar (light detection and ranging), positioning sensors, wheel angle sensors, and / or wheel speed sensors. The sensor units (including the ultrasonic sensor(s)) are each configured to output a sensor signal, for example, to the parking assistance system or driver assistance system, which performs semi-autonomous or fully autonomous driving based on the detected sensor signals.

[0049] Other possible implementations of the invention also include combinations of features or embodiments described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In such cases, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0050] Further advantageous embodiments and aspects of the invention are the subject of the dependent claims and the exemplary embodiments of the invention described below. The invention will be explained in more detail below with reference to preferred embodiments and the accompanying figures.

[0051] Fig. 1 schematically shows a top view of a proposed vehicle incorporating a proposed ultrasonic sensor and a proposed ultrasonic sensor circuit;

[0052] Fig. 2 schematically shows a system diagram to explain the structure and interaction of the described components and signals; Fig. 3 schematically shows an amplitude response of an ultrasonic sensor's response signal to an excitation test signal;

[0053] Fig. 4 schematically shows a phase response of an ultrasonic sensor's response signal to an excitation test signal;

[0054] Fig. 5 schematically shows a transmit gain curve and a receive gain curve for an ultrasonic sensor;

[0055] Fig. 6 schematically shows a transmit-receive gain curve for an ultrasonic sensor, which is determined from the characteristic curves of Fig. 5;

[0056] Fig. 7 schematically shows two ultrasound signal spectra that are symmetrical to each other with respect to a central frequency;

[0057] Fig. 8 schematically shows two characteristic curves, each comparing a proportion of a lower ultrasound signal spectrum and a proportion of a higher ultrasound signal spectrum for a medium frequency in a transmit-receive amplification curve;

[0058] Fig. 9 shows a flowchart of a proposed method for operating an ultrasonic sensor; and

[0059] Fig. 10 shows a flowchart of a proposed method for operating an ultrasonic sensor circuit.

[0060] In the figures, identical or functionally equivalent elements have been designated with the same reference numerals unless otherwise indicated. Fig. 1 shows a schematic bird's-eye view of a vehicle 100. The vehicle 100 is, for example, a car located in an environment 108. The car 100 has a parking assistance system 102, which is designed, for example, as a control device. Furthermore, a plurality of environmental sensor devices 104, 106 are arranged on the car 100, which are, for example, optical sensors 104 and ultrasonic sensors 106. The optical sensors 104 include, for example, visual cameras, a radar, and / or a lidar. The optical sensors 104 can each capture an image of a respective area from the environment 108 of the car 100 and output it as an optical sensor signal.The ultrasonic sensors 106 are configured to detect the distance to objects located in the surrounding area 108 and to output a corresponding sensor signal. Using the sensor signals detected by the sensors 104 and 106, the parking assistance system 102 is able to drive the car 100 semi-autonomously or even fully autonomously. In addition to the optical sensors 104 and ultrasonic sensors 106 shown in Fig. 1, the vehicle 100 may be equipped with various other sensor devices 104, 106, 114, 116. Examples include a microphone, an accelerometer, an antenna with a coupled receiver for receiving electromagnetically transmitted data signals, and the like.

[0061] Figure 2 shows a system diagram. For example, a body 110 of the vehicle 100 carries two ultrasonic sensors 106a and 106b. The vehicle 100 also includes a control unit 112 or a control device, a temperature sensor 114, and a brightness sensor 116, which are connected to the control unit 112, for example, via a bus or the like. The control unit 112 can, for example, be the control device 102 or a part or function thereof. The control unit 112 can, for example, be communicatively connected to the control device 102. The control unit can, for example, be separate from the ultrasonic sensors 106, 106a, 106b or be part of an ultrasonic sensor 106, 106a, 106b.

[0062] Each of the ultrasonic sensors 106, for example, has a housing 118, which is designed as a diaphragm 120 on one front side. An ultrasonic transducer 124 is attached to the diaphragm 120 in a cavity 122 of the housing 118. This transducer is configured to convert an electrical signal into an ultrasonic signal and vice versa. The ultrasonic transducer 124 is connected to a control logic unit 128 via a signal line 126. The control logic units 128 are connected to the control unit via further signal lines 130. All of the tasks of the control unit 112 described here can, for example, be performed by a control logic unit 128.

[0063] For example, the first ultrasonic sensor 106a emits an ultrasonic signal 132, which strikes an object 134 in the vicinity 108 of the vehicle 100. The ultrasonic signal 132 is reflected back to the first ultrasonic sensor 106a as a direct ultrasonic signal 136. The ultrasonic signal 132 is also reflected as an indirect ultrasonic signal 138 to the second ultrasonic sensor 106b.

[0064] A method M100 for operating, for example, the ultrasonic sensor 106a is now described with reference to the flowchart in Fig. 9. Method M100 can be executed, for example, by the control unit 112 or one of the control logics 128. Method M100 can also be executed, for example, by several or all of the control logics 128, which may interact, for example, as a distributed computer. Method M100 can also be executed, for example, by the control unit 112 and at least one of the control logics 128, preferably all of the control logics 128, working together.

[0065] In step S100, the execution of subsequent steps, e.g., steps S08–S134 of procedure M100, is initiated if the time interval since the last execution of procedure M100 exceeds a waiting threshold. The waiting threshold is preferably at least 5 minutes. The waiting threshold is preferably up to 30 minutes. The waiting threshold is, for example, 10 minutes. For example, the control unit 112 stores the time of the last execution of procedure M100 in a database 142. The database 142 is, for example, part of the control unit 112, but it can also be maintained in parallel and / or in one or more of the switching logics 128.

[0066] In step S102, the temperature of the ultrasonic sensor 106a is provided. The temperature of the ultrasonic sensor 106a specifically relates to the temperature of the membrane 120, which does not have its own temperature sensor. In the low-speed range, where ultrasonic sensors are currently preferred due to their range (e.g., during parking maneuvers), the membrane temperature is significantly influenced by the ambient temperature TL and solar radiation 140. For example, the ambient temperature T is used for this purpose. L The temperature is measured using the temperature sensor 114. Furthermore, the temperature TA of the control logic 128 is detected by the control logic 128. The membrane temperature T can then be determined, for example, using the following formula:

[0067] TM = a * TA + (1-a) * T La = Ri / ( Ri + R2 ) where Ri denotes a thermal resistance or thermal conductivity for a heat transfer between the membrane 120 and the (remaining) housing 118 and R2 denotes a thermal resistance for a heat transfer between the membrane 120 and the ambient air.

[0068] For example, the control unit 118 stores a membrane temperature TM from a last execution of procedure M100 in database 142. In step S104, an execution of the following steps, e.g., steps S08–S134 of procedure M100, is then started if the temperature of the ultrasonic device 116a, namely the membrane temperature T', has changed by more than a threshold value since the last execution of the procedure, for example, by 5°C. The membrane temperature TM can also be calculated and / or estimated, for example, based on the measured air temperature TL from temperature sensor 114 and the measured brightness from brightness sensor 116. It is also possible, for example, that the measured air temperature T L or a trend of the measured air temperature T L , and the measured brightness or a curve of the measured brightness are part of the input data set described below.

[0069] In step S106, the execution of subsequent steps, e.g., steps S08–S134 of method M100, is initiated when the speed of the vehicle 100 carrying the ultrasonic sensors 106 falls below a threshold speed. The threshold speed is preferably 35 km / h. The vehicle speed is read or provided, for example, via a CAN bus.

[0070] In step S108, a phase response of a response signal S is calculated. at of the ultrasonic sensor 106a. This can, for example, occur in a sequence of substeps S1 10 to S114, or, for example, in a sequence of substeps S1 16 to S120.

[0071] In step S1 10, a signal line 126, 130 of the ultrasonic sensor 106a is connected to an excitation signal S ar This is preferably the signal line 126, which is supplied with the excitation signal S by the control logic 128.ar is supplied with power. For example, it is also possible that the control unit supplies signal lines 130 and (subsequently) 126 with the excitation signal S. ar imposed.

[0072] The excitation signal S ar is preferably a "chirp" signal whose frequency increases with the duration of the signal, and whose amplitude preferably remains constant.

[0073] The excitation signal S ar In this case, for example, a weak excitation signal S ar , because it has an amplitude that is only 10% of the amplitude of a strong excitation signal S ar is. A strong excitation signal S ar is, for example, dimensioned to emit an ultrasound signal which is sufficient to generate an ultrasound signal reflected at an object 134, which reflected ultrasound signal can be converted into a response signal Sat, which in turn can be detected by the control logic 128.

[0074] The weak excitation signal S ar However, it is so strongly measured that it induces a characteristic waveform in the transducer 124 and the diaphragm 120. This characteristic waveform, in turn, causes a response signal S. at (of the ultrasonic transducer 124) in the signal line 126, which can be detected by the control logic 128.

[0075] The weak excitation signal S ar is simultaneously so weakly measured that it does not build up any residual energy in the control logic 128, which only after its decay allows for the recognition of a response signal S at allowed.

[0076] In other words: the excitation signal S ar is measured to provide a response signal S at to generate the ultrasound transducer 124 as well as to enable continuous or uninterrupted measurement of the excitation signal S ar and the response signal S at to allow.

[0077] The excitation signal S ardirectly generates an intrinsic waveform of the ultrasound transducer 124 coupled to the membrane 120, so that one can speak of an immediate response signal S at can speak. If - in contrast - the ultrasound transducer 124 coupled to the membrane 120 is used as a response signal S at the reflected ultrasound wave 136 is generated, which is a reflection of the excitation signal S ar The generated ultrasound wave 132 at the object 134 can, for the sake of easier differentiation, be distinguished from an indirect response signal S. at speak.

[0078] In step S1 12, a line signal of the signal line 126 or 130 is measured, while the signal line 126 or 130 is connected to the excitation signal S ar The signal is measured when the excitation signal is applied. Steps S110 and S112 are therefore executed simultaneously. The line signal can be described as the superposition of the excitation signal S. ar and the response signal S atThe measurement of the line signal can, for example, mean that the switching logic 128 records the line signal in the signal line 126, for example, by A / D conversion. The measurement of the line signal can, for example, mean that the control unit 112, in particular an input interface thereof, A / D converts the line signal in the signal line 130. The measured line signal is preferably in digital form.

[0079] In step S1 14, the response signal S at depending on the line signal and the excitation signal S ar determined. For example, the excitation signal S ar subtracted from the line signal.

[0080] The steps S1 10 to S1 14 above describe one exemplary way to measure the response signal S atto generate at any location and at any time. The following steps S1 16 to S120 describe an exemplary way to generate the response signal S at to be generated during the manufacture of the respective ultrasonic sensor 106 or the vehicle 100.

[0081] In step S1 16, a known ultrasound signal is generated by another ultrasound generator. For example, an ultrasound loudspeaker at a defined distance from the ultrasound sensor 106a is used to generate the known ultrasound signal. The ultrasound signal can be known, for example, by specifying an excitation signal to the loudspeaker and a transducer characteristic of the loudspeaker. Alternatively, the ultrasound signal can be known, for example, by recording the ultrasound signal in parallel with the ultrasound sensor 106a using an ultrasound signal with a known transducer characteristic.

[0082] In step S1 18, the line signal of the ultrasonic sensor 106a is recorded.

[0083] In step S120, the response signal S at The signal is determined depending on the line signal and the known ultrasound signal. For example, the ultrasound signal is input via a data interface of the switching logic 128 or the control unit 112, or stored and made available in the database 142.

[0084] In step S122, an input data record is created:

[0085] This is done from the response signal S at a phase response PG of the response signal S at generated. Figure 4 shows an example phase response PG. The input data set contains the phase response PG.

[0086] Additionally, for example, the response signal S can be used atAn amplitude response AG of the response signal Sat is generated. Figure 3 shows an example of an amplitude response AG. It should be noted, however, that the specific amplitude response AG in Figure 3 is not generated from the same response signal S. at The specific phase response PG of Fig. 4 was not generated, but different response signals S were used for illustrative purposes. at Different frequency range widths were used. The amplitude response AG can be included in the input data set.

[0087] Additionally, for example, the known ultrasound signal of step S116 or a representation of the waveform of the ultrasound signal can be included in the input data set.

[0088] Additionally, for example, the line signal measured in S112 or S118, or a representation of the line signal's waveform, can be included in the input data set.

[0089] Additionally, a set of parameters can be included in the input data set. These parameters characterize an equivalent circuit of the ultrasonic sensor and were determined during commissioning (typically at the end of manufacturing). The parameters can be stored, for example, in database 142. It is not necessary, but synergistically advantageous, to include the parameters in the input data set when the procedure is executed using a generic trained model. Conversely, it is not necessary, but synergistically advantageous, to omit the parameters from the input data set when the procedure is executed using a customized or at least individually adapted trained model.

[0090] Additionally, an indicator for the age of the ultrasonic sensor 106a can be included in the input data set. For example, a manufacturing date of the ultrasonic sensor 106a can be stored in database 142, which can be converted into its age using a current date.

[0091] Additionally, an indicator for the operating time of the ultrasonic sensor 106a can be recorded, such as the number of operating hours or minutes and / or the number of ultrasonic signals transmitted. For example, a counter is stored in database 142, the value of which is incremented by one with each transmission of an ultrasonic signal.

[0092] Additionally, for example, the temperature determined in S102 or a representation of this temperature can be included in the input data set.

[0093] The aforementioned additional elements of the input dataset are not specified in any particular order. Each of the additional elements can be included in the input dataset individually or in combination with at least one other element. Preferably, each input dataset, including input datasets during model training, contains the same elements.

[0094] In step S124, a characteristic curve data set is determined by the trained model as a function of the input data set. The trained model is provided, for example, by means of database 142. The characteristic curve data set contains, for example, a characteristic curve of a transmit gain curve Vs or a representation of the transmit gain curve Vs. The transmit gain curve specifies, for several frequencies or a multitude of frequencies, the gain of the ultrasonic sensor 106a when converting an excitation signal S. arinto an ultrasound signal 132. The amplification is given, for example, in dB.

[0095] The characteristic curve data set contains, for example, a characteristic curve of a receiver gain curve V. E or a representation thereof. The reception amplification corridor V E For several frequencies, the ultrasound sensor 106a provides an amplification when converting an ultrasound signal 136, 138 into a response signal S. at The amplification is specified, for example, in dB.

[0096] The characteristic curve data set contains, for example, a characteristic curve of a transmit-receive gain curve VSE or a representation thereof. The transmit-receive gain curve VSE, for example, specifies the gain of the ultrasonic sensor 106a for several frequencies when converting an excitation signal S. ar into an ultrasound signal 132 and back from an incoming ultrasound signal 136, 138 into a response signal S atfor example in dB.

[0097] Fig. 5 shows an example of a transmit gain curve Vs and a receive gain curve V. E , and Fig. 6 shows an example of a corresponding transmit-receive gain curve VSE.

[0098] In an optional substep S126, the trained model additionally outputs an evaluation indicator. In other words, the trained model outputs both the characteristic curve data set and at least one evaluation indicator for each input data set. The evaluation data set is an assessment (by the trained model based on / depending on the input data set) of whether a state of the ultrasonic sensor meets an operating specification. The trained model was previously trained using a large number of input data sets as training data and a corresponding characteristic curve data set for each as an objective function / object function. The training was performed, for example, at the factory. Evaluation indicators corresponding to the training data were also part of the training as additional objective functions.

[0099] In step S128, a setting for the ultrasonic sensor 106a is specified based on the characteristic curve data set. Specifying here means, for example, setting it to a predefined value. Specifying includes, for example, changing or keeping the value constant, depending on the initial state.

[0100] For example, in direct operation of the ultrasonic sensor 106a, the respective setting is determined depending on the transmit / receive gain curve VSE. For example, in indirect operation, the respective setting of the transmitting ultrasonic sensor 106a is determined depending on the transmit gain curve Vs, and the respective setting of the receiving ultrasonic sensor 106b is determined depending on the receive gain curve V. E specified.

[0101] In step S130, a criteria data set is provided. For example, the criteria data set contains an absolute upper limit, a frequency-dependent upper limit, an absolute lower limit, and / or a frequency-dependent lower limit for the receive gain response V. E , for the transmit gain Vs and / or for the transmit / receive gain VSE.

[0102] In step S132, based on the characteristic curve data set determined in S124 and the criteria data set provided in S130, it is determined whether a state of the ultrasonic sensor 106a meets an operating specification. For this purpose, the characteristic curve(s) are compared with the limit value(s), and by detecting whether the lower limit(s) are undershot or the upper limit(s) are exceeded, it is recognized that the state of the ultrasonic sensor 106a does not meet the operating specification. Therefore, it is not necessary to check the operating specification itself. Thus, the check can be performed quickly and with low computational effort.

[0103] In step S134, a warning message is issued to a user of the vehicle 100 if S126 and / or S132 determine that the condition of the ultrasonic sensor 106 does not meet the operating specification. For example, a display is activated on a dashboard, or a corresponding message is sent to a stored address, including an email address or mobile phone number.

[0104] In step S136, the ultrasonic sensor 106a is operated to emit an ultrasonic signal 132, for example to detect an object 134 in the vicinity 108 of the vehicle 100.

[0105] The following briefly describes a method M200 for operating an ultrasonic sensor circuit 144. The ultrasonic sensor circuit 144 contains at least two acoustically adjacent ultrasonic sensors 106, for example, the ultrasonic sensors 106a and 106b.

[0106] First, the previously described steps S100 to S126 and S130 to S134 are performed for each of the ultrasonic sensors. This means that a set of characteristic curves is determined for each of the two ultrasonic sensors 106a and 106b. Specifically, the transmit gain Vs is determined for the first ultrasonic sensor 106a, and the receive gain V is determined for the second ultrasonic sensor 106b. E determined.

[0107] Then, in step S202, two ultrasound frequencies are determined based on the determined characteristic curve data sets. These frequencies have a defined frequency separation from each other. More precisely, two ultrasound frequencies are determined that together offer maximum gain at the defined frequency separation. A combined transmit / receive gain (VSE) for the transmission path is then calculated from these two characteristic curves: excitation signal S arto the first ultrasonic sensor 106a, ultrasonic signal 132, ultrasonic signal 138 and response signal S at from the second ultrasonic sensor 106b. For this purpose, the respective value of the receive gain V is determined for each frequency. E subtracted from the respective value of the transmit gain curve Vs.

[0108] Two frequency spectra, Fi and F2, are then provided, each with a cosine wave magnitude. Both spectra are exactly zero at a central frequency, each is exactly one period wide above or below the central frequency, and both are constant zero in the opposite direction (below or above) from the central frequency. The frequency spectra Fi and F2 are shown in Fig. 7. The frequency spectra Fi and F2 and the combined transmit / receive gain VSE have the same frequency resolution over their respective entire bandwidths. Half the period of the frequency spectra is chosen to correspond to the frequency offset between the sideband and the nominal frequency of the ultrasonic sensor circuit 144, for example, 3.75 kHz.

[0109] Next, the following calculation is performed for each frequency (hereinafter: calculation frequency) of the common transmit-receive gain response VSE:

[0110] 1) The average frequency of the frequency spectra is set to the computing frequency;

[0111] 2) then, for each spectrum frequency of the first frequency spectrum Fi, the value of this frequency spectrum at that spectrum frequency is multiplied by the value of the common transmit-receive gain response VSE at the frequency of the common transmit-receive gain response VSE, which is equidistant from the calculation frequency as that spectrum frequency of the frequency spectrum is from the center frequency; and

[0112] 3) then these products are summed, or one could say: integrated.

[0113] This results in a summation line S1 of the products at the respective computing frequencies.

[0114] This summation curve S1 can be described as a convolution of the first frequency spectrum Fi with the common transmit / receive gain response VSE. Similarly, a summation curve S2 is calculated as a convolution of the second frequency spectrum F2 with the common transmit / receive gain response VSE. The summation curves S1 and S2 are shown in Fig. 8.

[0115] Figure 8 shows an intersection point for the summation lines S1 and S2. This intersection point is characterized by the fact that the transmit gain of the first ultrasonic sensor 106a and the receive gain of the second ultrasonic sensor 106b are each nearly equal (i.e., equally effective) for half a period of the frequency spectra below and above the intersection point. Therefore, based on the homogeneity of the transmit and receive gains, the intersection point corresponds to an optimal nominal frequency for the ultrasonic sensor circuit 144.

[0116] In step S202, the two ultrasonic frequencies that are spaced apart from the nominal frequency by a sideband are determined.

[0117] In the example of Figs. 8 and 7, the optimal nominal frequency is 53.5 kHz, the sideband spacing is 3.75 kHz, and the determined ultrasonic frequencies are therefore 49.75 kHz and 57.25 kHz.

[0118] In the next step S204, a respective transmission frequency for each of the ultrasonic sensors 106a, 106b is set to one of the two determined ultrasonic frequencies. For example, the transmission frequency of the first ultrasonic sensor 106a is set to 49.75 kHz, and the transmission frequency of the second ultrasonic sensor 106b is set to 57.25 kHz.

[0119] As a result, the ultrasonic sensors 106a and 106b of the ultrasonic sensor circuit 144 are set so that, on the one hand, an object can be detected in direct operation without interference from the other ultrasonic sensor (because the frequency of the ultrasonic signal 136, 138 is distinguishable, the transmitting ultrasonic sensor 106 can be identified from the response signal S). ar (detectable). On the other hand, the ultrasonic sensors 106 can receive the indirect ultrasonic signals 136, 138 with the same amplification. Therefore, the amplitude of the ultrasonic signal is comparable, so that the object 134 can be detected with high precision.

[0120] The line signal, the excitation signal S ar , the known ultrasound signal, one of the ultrasound signals 132, 136 and / or 138 and / or the response signal S atThey can each be described, for example, as a time series, with a signal strength preferably being recorded and stored at each sampling point. The phase response PG, the amplitude response AG, the transmit gain response Vs, the receive gain response V E , the transmit-receive gain response VSE, the frequency spectra Fi and / or F2 and / or the summation lines Si and / or S2 can each be described as a series of values, preferably with a value (gain value) stored for each frequency interval of a frequency bandwidth.

[0121] It can therefore be said that steps S202 and S204 fulfill the tasks / function of step S128 in whole or in part, namely to specify at least one setting of at least one ultrasonic sensor 106, 106a, 106b depending on a respective characteristic curve data set.

[0122] In step S136, the ultrasonic sensors 106a and 106b are then operated individually or together to emit a respective ultrasonic signal 136. Thus, for example, an object 134 can be detected with respect to each of the ultrasonic sensors 106a and 106b and / or with respect to a known relative arrangement of the two acoustically adjacent ultrasonic sensors 106a and 106b.

[0123] As a result of both methods M100 and M200, the ultrasonic sensor 106 and the ultrasonic sensor circuit 144, respectively, can detect and locate the object 134 with high precision.

[0124] Although the present invention has been described with reference to exemplary embodiments, it can be modified in many ways. In particular, the proposed method may include further steps, or fewer steps, than those described above for illustrative purposes.

[0125] Steps S100 to S204.

[0126] REFERENCE MARK LIST

[0127] 100 vehicles

[0128] 102 Parking Assistance System

[0129] 104 optical sensor

[0130] 106 Ultrasonic sensor

[0131] 106a first ultrasonic sensor

[0132] 106b second ultrasonic sensor

[0133] 108 surroundings

[0134] 110 bodywork

[0135] 112 Control unit

[0136] 114 Temperature sensor

[0137] 116 Brightness sensor

[0138] 118 cases

[0139] 120 Membran

[0140] 122 cavity

[0141] 124 ultrasound transducers

[0142] 126 Signal line

[0143] 128 Control Logic

[0144] 130 Signal line

[0145] 132 Ultrasound signal

[0146] 134 objects

[0147] 136 direct ultrasound signal

[0148] 138 indirect ultrasound signal

[0149] 140 solar radiation

[0150] 142 database

[0151] 144 Ultrasonic sensor circuit

[0152] AG Amplitude gang

[0153] Fi frequency spectrum F2 frequency spectrum

[0154] PG phase response

[0155] TM Membrane temperature

[0156] Air temperature

[0157] T A Control logic temperature

[0158] 51 Summary line

[0159] 52 Sum line

[0160] Vs transmitter gain curve

[0161] V E Receiver amplification circuit

[0162] VSE transmit-receive amplification circuit

[0163] M100 Method for operating an ultrasonic sensor

[0164] S100 Execute the procedure if the time interval since the last execution of the procedure exceeds a waiting threshold

[0165] S102 Providing a temperature from the ultrasonic sensor

[0166] S104 Execute the procedure if the temperature of the ultrasound device has changed by more than one threshold value since the last execution of the procedure

[0167] S106 Execution of the procedure when the speed of a vehicle carrying the ultrasonic sensor falls below a threshold speed

[0168] S108 Providing a phase response of a response signal from the ultrasonic sensor

[0169] S110 Applying an excitation signal to a signal line of the ultrasonic sensor

[0170] S112 Measuring a line signal of the signal line during impingement

[0171] S114 Determining the response signal as a function of the line signal and the excitation signal

[0172] S116 Generating a known ultrasound signal by another ultrasound generator

[0173] S118 Measuring the line signal of the ultrasonic sensor;

[0174] S120 Determining the response signal as a function of the line signal and the known ultrasound signal S122 Creating an input data set

[0175] S124 Determining a characteristic curve data set by a trained model depending on an input data set

[0176] S126 Output an assessment indicator S128 Specify a setting of the ultrasonic sensor depending on the characteristic curve data set

[0177] S130 Providing a criteria data set;

[0178] S132 Assess, based on the determined characteristic curve data set and the criteria data set, whether a state of the ultrasonic sensor meets an operating specification.

[0179] S134 Issue a warning message to a user

[0180] S136 Emitting an ultrasonic signal by the ultrasonic sensor

[0181] M200 Method for operating an ultrasonic sensor circuit

[0182] S202 Determining two ultrasound frequencies that have a defined frequency difference from each other, depending on the determined characteristic curve data sets

[0183] S204 Specifying a respective transmission frequency for each of the ultrasonic sensors on one of the two determined ultrasonic frequencies.

Claims

PATENT CLAIMS 1. Method (M100, M200) for operating an ultrasonic sensor (106, 106a, 106b), comprising: Providing (S108) a phase response (PG) of a response signal (S at ) of the ultrasonic sensor (106, 106a, 106b); Determining (S124) a characteristic curve data set by a trained model as a function of an input data set, wherein the input data set contains the phase response (PG), and wherein the characteristic curve data set contains a transmit gain response (Vs), a receive gain response (V) E ) and / or a transmit-receive gain response (VSE) corresponding to a difference between the transmit gain response (Vs) and the receive gain response (Vs) with respect to the ultrasonic sensor (106, 106a, 106b); Specifying (S128) a setting of the ultrasonic sensor (106, 106a, 106b) depending on the characteristic curve data set.

2. Method according to claim 1, characterized in that the provision (S108) of the phase response (PG) includes: Applying (S110) a signal line (126, 130) of the ultrasonic sensor (106, 106a, 106b) with an excitation signal (S ar ), wherein a signal power for obtaining the phase response (PG) is up to 50%, preferably up to 30% and more preferably up to 20% of a signal power suitable for detecting an object (134), and wherein a frequency of the excitation signal (S ar ) is changed; Measuring (S112) a line signal of the signal line (126, 130) during the application (S110); and Determining (S114) the response signal (S at ) depending on the line signal and the excitation signal (S ar ).

3. Method according to claim 1, characterized in that the provision (S108) of the phase response (PG) includes: Generating (S116) a known ultrasound signal (136, 138) by another Ultrasound generator, in which a frequency of the ultrasound signal is changed; Measuring (S118) the line signal of the ultrasonic sensor (106, 106a, 106b); and determining (S120) the response signal (S at ) depending on the line signal and the known ultrasound signal.

4. Method according to one of the preceding claims, characterized in that the input data set additionally contains at least one of the following pieces of information: a provided amplitude response (AG) of the response signal (S). at ), the excitation signal (S ar), the ultrasonic signal (136, 138), the measured line signal, a set of parameters of an equivalent circuit describing the ultrasonic sensor (106, 106a, 106b) determined during commissioning of the ultrasonic sensor, and / or an indicator of the age of the ultrasonic sensor (106, 106a, 106b) and / or of the operating time provided by the ultrasonic sensor (106, 106a, 106b).

5. A method according to any of the preceding claims, characterized in that the method comprises: Providing (S102) a temperature (T L , T A , T M ) of the ultrasonic sensor (106, 106a, 106b), in particular a measured ambient air temperature (T L ), a measured circuit temperature (T A ) an electrical circuit (128) in the ultrasonic sensor (106, 106a, 106b) and / or a membrane temperature (T M ), which depend on the ambient air temperature (T ), the circuit temperature (T )A ) and / or a measured solar irradiance (140); wherein the input data set additionally includes at least the provided temperature (T L , T A , T M ) contains.

6. Method according to one of the preceding claims, characterized in that The model is trained to output an assessment indicator in addition to the characteristic curve data set based on the input data set, where the assessment indicator is indicative of whether a state of the ultrasonic sensor (106, 106a, 106b) meets an operating specification; the method (M100) includes: Output (S134) a warning information to a user if the trained model, depending on the input data set, outputs an assessment indicator that is indicative for the assessment that the condition of the ultrasonic sensor (106, 106a, 106b) does not meet the operating specification.

7. A method according to any of the preceding claims, characterized in that the method comprises: Providing (S130) a criteria data set; Assess (S132) based on the determined characteristic curve data set and the criteria data set whether a state of the ultrasonic sensor (106, 106a, 106b) meets an operating specification; and Issue (S134) a warning message to a user if the assessment determines that the condition of the ultrasonic sensor does not meet the operating specification.

8. Method according to one of the preceding claims, characterized in that the time interval between two embodiments of the method (M100) is preferably longer than 5 minutes and preferably shorter than 30 minutes.

9. Method according to one of the preceding claims, characterized in that the method (M100) is carried out if a temperature (T) L , T A , TM ) of the ultrasonic sensor (106, 106a, 106b) has changed by more than one threshold value since a last execution of the procedure (M100).

10. Method (M200) for operating an ultrasonic sensor circuit (144) comprising at least two acoustically adjacent ultrasonic sensors (106a, 106b), comprising: Performing steps (S102 to S124) of the method (M100) according to one of claims 1 to 9 up to and including determining (S124) the characteristic curve data set for each of the ultrasonic sensors (106a, 106b); Determine (S202) two ultrasound frequencies that have a defined frequency difference from each other, depending on the determined characteristic curve data sets; and Specifying (S204) a respective transmission frequency for each of the ultrasonic sensors (106a, 106b) to one of the other two determined ultrasonic frequencies.

11. Computer program product comprising instructions which, when the program is executed by a computer, cause it to execute the method (M100, M200) according to any one of claims 1-10.

12. Ultrasonic sensor (106, 106a, 106b) configured for operation by means of the method (M100, M200) according to any one of claims 1 to 10.

13. Ultrasonic sensor circuit (144) comprising at least two acoustically adjacent ultrasonic sensors (106a, 106b), wherein the ultrasonic sensor circuit (144) is configured for operation by means of the method (M200) according to claim 10.

14. Control unit (112) for controlling an ultrasonic sensor (106, 106a, 106b) or an ultrasonic sensor circuit (144) which is configured to carry out the method according to one of claims 1 - 10.

15. Vehicle (100) comprising an ultrasonic sensor (106, 106a, 106b) according to claim 12, an ultrasonic sensor circuit (144) according to claim 13 and / or a control unit according to claim 14.

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