Ultrasonic sensor system of a motor vehicle and method of operating an ultrasonic sensor system

Abstract

An ultrasonic sensor system (1) for a motor vehicle (11) is proposed, comprising an ultrasonic sensor (2) and a test control device (10). The ultrasonic sensor (2) comprises an electroacoustic transducer arrangement (7) for generating and detecting ultrasonic waves, and an electrical test device (8) designed to output an electrical test signal to the electroacoustic transducer arrangement (7) and to detect an electrical response signal of the electroacoustic transducer arrangement (7) to the electrical test signal. The test control device (10) is designed to detect characteristic variables of the electrical response signal at a plurality of measurement points (14, 15) by the electrical test device (8) by varying a frequency and an amplitude of the electrical test signal.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic sensors for motor vehicles, and more specifically, to an ultrasonic sensor system for motor vehicles and a method for operating the ultrasonic sensor system. Background Technology

[0002] An ultrasonic sensor is known, comprising an arrangement of electroacoustic transducers for generating and detecting ultrasonic waves, used to measure the distance to an object in a motor vehicle environment. In this case, ultrasonic waves are emitted, and the echo signals returning from the vehicle environment are captured. The distance to the object is determined based on the signal transit time. This measurement is used, for example, by a driving or parking assistance system of a motor vehicle.

[0003] Measurement results may be corrupted due to internal or external variations in the arrangement of the electroacoustic transducers, such as the effects of aging-related fields of piezoelectric elements, or ultrasonic sensors may fail over time. Therefore, multiple ultrasonic sensors can be provided on a vehicle, and the measurements provided by each sensor can be reliably checked before evaluation. However, this reliability check may also incorrectly reject essentially usable measurements when the electrical characteristics of the ultrasonic sensors change gradually.

[0004] EP 2347231 B1 teaches a functional monitoring device that determines the impedance characteristic curve of an ultrasonic sensor based on the excitation frequency. When determining the impedance characteristic curve, the ultrasonic sensor is excited with a smaller and constant amplitude compared to normal measurement operation.

[0005] DE 102012216968 A1 teaches how to measure the impedance of an ultrasonic transducer using a test signal and compares the change in impedance at the frequency of the test signal with a reference to the extreme points present in the impedance curve. The amplitude of the test signal differs from the amplitude used to measure distance.

[0006] DE 102014201482 A1 teaches how to determine the impedance profile of an ultrasonic transducer by scanning an excitation signal within a specific frequency range of a constant voltage amplitude.

[0007] DE 102017203136 A1 teaches a monitoring unit for a sound sensor that measures the impedance of a sound transducer for different excitation frequencies. In this case, the amplitude of the excitation of the sound transducer is preferably 10 to the power of one less than the amplitude used to measure the distance. Summary of the Invention

[0008] In view of this background technology, the purpose of this invention is to improve the determination of the state of ultrasonic sensors.

[0009] Accordingly, an ultrasonic sensor system for motor vehicles is proposed. The proposed ultrasonic sensor system includes an ultrasonic sensor and an electrical testing device. The ultrasonic sensor has an electroacoustic transducer arrangement for generating and detecting ultrasonic waves. The electrical testing device is configured to output an electrical test signal to the electroacoustic transducer arrangement and capture the electrical response signal from the electroacoustic transducer arrangement to the electrical test signal. The proposed ultrasonic sensor system also includes a test control device configured to use the electrical testing device to capture characteristic variables of the electrical response signal, while simultaneously changing the frequency and amplitude of the electrical test signal at multiple measurement points.

[0010] An electroacoustic transducer arrangement may specifically include an ultrasonic diaphragm, a sound transducer device (e.g., a piezoelectric element) attached to the ultrasonic diaphragm and having a mechanical capacitance, mechanical resistance, magnetostriction, or electrostriction operating principle, and a coupling circuit for matching the impedance of the sound transducer device.

[0011] In particular, this electroacoustic transducer arrangement can be understood as a nonlinear electrical arrangement with resistive, inductive, and capacitive components.

[0012] By changing not only the frequency but also the amplitude of the test signal, the proposed method of capturing electrical characteristic variables at multiple measurement points can be advantageously used to capture at least a portion of the multidimensional characteristic diagram of an electroacoustic transducer arrangement, and thus takes into account the nonlinear amplitude dependence of the characteristic variables.

[0013] Because of this consideration of the amplitude dependence of the electrical characteristic variables of the electroacoustic transducer arrangement, it is possible to significantly improve the characteristics of the ultrasonic sensor's state, and accordingly, the vehicle's higher-level control unit can respond much better to changes in the ultrasonic sensor's state.

[0014] The term "measurement point" can specifically refer to a precise combination of a frequency and a precise amplitude of a test signal.

[0015] Accordingly, the test control equipment can specifically capture multiple characteristic variables, one for each measurement point. The characteristic variables acquired at multiple measurement points can specifically form characteristic curves or two-dimensional or multi-dimensional characteristic diagrams of the electroacoustic transducer arrangement of the ultrasonic sensor.

[0016] The electrical test signal can specifically be an oscillation of electrical characteristic variables applied to an electroacoustic transducer arrangement, such as a current or voltage with a defined amplitude and a defined frequency. The amplitude and frequency of the test signal can be constant at each measurement point, particularly within the time period during which the characteristic variables of the response signal are captured at the measurement point.

[0017] Specifically, the electrical response signal can be an oscillation of one of the characteristic variables (such as voltage or current) that is captured in the electroacoustic transducer arrangement when an electrical test signal is applied to the electroacoustic transducer arrangement.

[0018] The electrical test equipment can be formed by circuitry provided in an ultrasonic sensor and can be controlled by a test control device to generate an electrical test signal having a frequency and amplitude specified by the test control device in each case, and can be used by the test control device to capture an electrical response signal.

[0019] Test control equipment can be integrated into the ultrasonic sensor, or it can be provided externally to the ultrasonic sensor.

[0020] Test control equipment can be specifically formed from application-specific integrated circuits (ASICs), microprocessors, electronic control units (ECUs), etc.

[0021] The process of capturing characteristic variables at multiple measurement points by changing the frequency and amplitude of the test signal through a test control device can also be referred to as the "test operation" of an ultrasonic sensor. The process of controlling an electroacoustic transducer arrangement to generate ultrasonic waves and subsequently capturing the reflected ultrasonic waves in order to measure distance can also be referred to as the "measurement operation" of an ultrasonic sensor.

[0022] According to one embodiment, the electrical test signal is a constant current signal, and the corresponding characteristic variables include the voltage amplitude and / or phase angle of the response signal at the corresponding measurement point at the frequency and amplitude of the electrical test signal.

[0023] Therefore, one or more characteristic variables can be captured at each measurement point. Preferably, at least the voltage amplitude of the response signal is captured. Furthermore, it is also particularly preferred to capture the phase angle of the voltage of the response signal. In this way, both the real and complex numerical portions of the response of the electroacoustic transducer arrangement can be advantageously and completely captured.

[0024] By selecting a constant current signal (a signal with a constant current amplitude), the testing operation of the ultrasonic sensor can be advantageously performed under the same conditions as the current-controlled measurement operation of the ultrasonic sensor.

[0025] However, as an alternative, it can be envisioned that the electrical test signal can be a constant voltage signal, and the corresponding characteristic variables can be the amplitude and / or phase angle of the current intensity of the response signal at the frequency and amplitude of the electrical test signal at the corresponding measurement point.

[0026] According to a further embodiment, when performing distance measurement, multiple measurement points of the test signal are selected as operation points corresponding to the control signals of the ultrasonic sensor.

[0027] This means that the testing operation of the ultrasonic sensor can be performed using the same frequency and amplitude of the test signal, which is also used as the control signal during the measurement operation of the ultrasonic sensor.

[0028] Thus, the characteristic plots captured during the test operation (characteristic variables captured at multiple measurement locations) can advantageously characterize the resistance, inductance, and capacitance characteristics of the electroacoustic transducer at amplitudes and frequencies associated with the measurement operation. The characteristics obtained in this way can be advantageously used to adjust the parameters of the measurement operation, and therefore enable the continued use of ultrasonic sensors with time-varying operational behavior.

[0029] According to a further embodiment, for multiple different frequencies within a frequency range, each of the multiple measurement points includes exactly one measurement point. Here, the amplitude of the corresponding measurement point is selected based on the frequency of the measurement point.

[0030] In particular, correspondingly, multiple measurement points cannot cover the entire characteristic map, but it is advantageous to select a one-dimensional path along the characteristic map through the ultrasonic sensor, the one-dimensional path being particularly non-linear and particularly nonlinear.

[0031] It is theoretically feasible to fully test a specified frequency range and a specified amplitude range during a test operation, thereby determining a complete characteristic profile of the ultrasonic sensor. However, if only one measurement point is precisely captured for each of several different frequencies, the test can be completed in a shorter time during the test operation. In particular, the test operation can therefore be performed during a pause between two measurement cycles of the ultrasonic sensor's measurement operation, without the ultrasonic sensor's measurement operation needing to be interrupted for the test.

[0032] This makes "online testing" possible.

[0033] In this case, the amplitude of the corresponding measurement point can preferably be selected as the amplitude at which the control signal is applied to the electroacoustic transducer arrangement during measurement operations at the same frequency. Therefore, advantageously, only the characteristic variables related to the measurement operation can be captured.

[0034] The frequency range can be selected according to the requirements of the measurement operation. The frequency range may particularly include a frequency of 50 kHz. The frequency range may particularly preferably cover the range from 40 kHz to 60 kHz, and very particularly preferably cover the range from 30 kHz to 70 kHz.

[0035] According to a further embodiment, multiple measurement points within the frequency range are selected to be closer together in a first frequency portion than in a frequency portion where a gradient lower than the high gradient was determined, in which a high gradient of the characteristic variable to be captured was determined during previous testing of the electroacoustic transducer arrangement.

[0036] In this context, "previous testing" can be specifically associated with the actual execution of the test operation. In particular, "previous testing" can be associated with the last execution of the test operation. Thus, during the lifespan of the ultrasonic sensor, the frequency range where the measurement points are selected to be closer together can be adaptively adjusted to the region in the characteristic curve where nonlinearity is detected. Alternatively, "previous testing" can be associated with the test operation performed during the manufacture of the ultrasonic sensor. However, "previous testing" can also be specifically associated with the theoretical determination of the characteristic curve, and therefore with the target characteristic curve, i.e., where nonlinearity in the response of the electroacoustic transducer arrangement is expected, the measurement points can be selected to be close together.

[0037] Accordingly, the number of measurements to be performed can be advantageously reduced, thereby reducing the time interval required for test operations, and / or improving the accuracy of determining the characteristic map in the region of interest.

[0038] According to a further embodiment, among the amplitudes of two measurement points at adjacent frequencies within a frequency range, one amplitude is selected at the lower limit of the amplitude range selected based on the adjacent frequencies, and another amplitude is selected at the upper limit.

[0039] The amplitude range of the corresponding frequency can be specifically selected, for example, in such a way that it covers a predetermined tolerance range around the amplitude, during which control signals are applied to the electroacoustic transducer arrangement at the same frequency.

[0040] In particular, although only one measurement is required for each of the multiple frequencies (capturing only one characteristic variable), it is advantageous to select multiple measurement points along two one-dimensional paths through the characteristic map of the ultrasonic sensor, which describe the boundaries of the two-dimensional bands within the characteristic map.

[0041] According to a further embodiment, the test control device is configured to report the status of the electroacoustic transducer arrangement to the control device of the motor vehicle based on a plurality of characteristic variables captured by the test control device.

[0042] Specifically, the test control equipment can evaluate multiple captured characteristic variables, and depending on the result of the evaluation, can report an error state or, for example, a "ready to operate" state to the vehicle's control unit. Alternatively, it can report to the control unit only when an error state is detected.

[0043] For example, test control equipment can compare captured characteristic variables describing characteristic curves or multidimensional characteristic plots with target characteristic curves or target characteristic plots, and can determine error states or "ready to operate" states based on the comparison results.

[0044] Accordingly, the vehicle's control unit can troubleshoot ultrasonic sensors from environmental measurements and / or output error messages to the vehicle's operator or maintenance personnel.

[0045] According to a further embodiment, the ultrasonic sensor system also includes a measurement control device configured to excite an electroacoustic transducer arrangement to emit ultrasonic waves by applying an electrical control signal, and to perform distance measurement by subsequently capturing and evaluating an electrical detection signal from the electroacoustic transducer arrangement. In this case, the measurement control device is configured to perform distance measurement based on a plurality of characteristic variables captured by the test control device.

[0046] Measurement and control equipment can be integrated into the ultrasonic sensor or provided externally to the ultrasonic sensor.

[0047] Measurement and control equipment can be specifically formed from application-specific integrated circuits (ASICs), microprocessors, electronic control units (ECUs), etc.

[0048] The electrical control signal can be, in particular, a constant current signal with a constant frequency. However, scanning within a predetermined frequency range is also feasible and preferred.

[0049] "Electrical detection signal" can be understood as a signal that is returned to the measurement and control equipment, particularly by an electroacoustic transducer arrangement. When an ultrasonic wave is incident on an electroacoustic transducer arrangement (its ultrasonic diaphragm) and converted into such an echo signal pulse by the electroacoustic transducer arrangement (its piezoelectric element, etc.), the electrical detection signal can include an echo signal (echo signal pulse).

[0050] During the measurement operation, the echo signal in the detection signal can be determined. Based on the transit time difference between the application of the electronic control signal and the appearance of the echo signal in the detection signal, the distance to obstacles in the motor vehicle environment can be inferred.

[0051] Specifically, the following can be adjusted based on characteristic variables captured by the test control equipment: control signals (their frequency, frequency range, and / or amplitude), and / or thresholds used to determine the echo signal in the detection signal, and / or gain factors used to amplify the detection signal before determining the echo signal.

[0052] According to the proposal, the reliability and accuracy of distance measurements can be advantageously improved if the electrical characteristic variables (the electrical characteristic diagram of the electroacoustic transducer arrangement) are known and taken into account when performing distance measurements.

[0053] According to a further embodiment, the ultrasonic sensor includes a test control device.

[0054] The ultrasonic sensor preferably also includes measurement and control equipment. Particularly preferably, the test and control equipment, and possibly additional measurement and control equipment, can be designed as part of an application-specific integrated circuit (ASIC) disposed on a printed circuit board within the housing of the ultrasonic sensor.

[0055] Accordingly, it is advantageous to provide ultrasonic sensors with a longer service life and / or continuously improving measurement quality during their service life.

[0056] According to the second aspect, a motor vehicle having at least one ultrasonic sensor system as described above is proposed.

[0057] The features, advantages, and embodiments described for the ultrasonic sensor system of the first aspect are also applicable to the motor vehicle of the second aspect.

[0058] Motor vehicles can, in particular, be passenger cars or trucks. Motor vehicles may have assistance systems, such as driver assistance systems or parking assistance systems, which can be specifically configured for semi-autonomous or fully autonomous driving of the vehicle. Semi-autonomous driving is understood to mean, for example, that the assistance system controls the steering mechanism and / or the automatic gear selection system. Fully autonomous driving is understood to mean, for example, that the assistance system additionally controls the drive and braking devices. Assistance systems can be implemented in hardware and / or software. In the case of hardware implementation, the assistance system can be, for example, in the form of a computer or microprocessor. In the case of software implementation, the assistance system can be in the form of a computer program product, function, routine, part of program code, or executable object. In particular, the assistance system can be in the form of part of the vehicle's higher-level control system, such as an ECU (engine control unit). The assistance system can use the proposed ultrasonic sensor system to monitor or measure the environment of the motor vehicle using ultrasonic measurements via the pulse-echo method.

[0059] According to one embodiment of this aspect, the corresponding ultrasonic sensors respectively include a test control device and a measurement control device. According to another embodiment of this aspect, the proposed test control device can be provided centrally once in the control device of a motor vehicle, and can control the test operation of each of the multiple ultrasonic sensors.

[0060] According to a third aspect, a method is proposed for an ultrasonic sensor system for operating a motor vehicle. The ultrasonic sensor system includes an ultrasonic sensor having an electrical testing device and an electroacoustic transducer arrangement for generating and detecting ultrasonic waves, and also includes a test control device. The method includes the following steps: outputting an electrical test signal to the electroacoustic transducer arrangement through the testing device; capturing an electrical response signal from the electroacoustic transducer arrangement through the testing device; and capturing characteristic variables of the electrical response signal at multiple measurement points through the test control device, while changing the frequency and amplitude of the electrical test signal.

[0061] The features, advantages, and embodiments described for the ultrasonic sensor system of the first aspect are also applicable to the method of the third aspect.

[0062] Further possible embodiments of the invention include combinations of features or embodiments not explicitly mentioned in the descriptions above or below with reference to exemplary embodiments. In such cases, those skilled in the art will also add individual aspects as improvements or additions to the corresponding basic form of the invention. Attached Figure Description

[0063] Further advantageous configurations and aspects of the invention are the subject of the dependent claims and exemplary embodiments of the invention described below. The invention will now be explained in more detail based on preferred exemplary embodiments with reference to the accompanying drawings.

[0064] Figure 1 A schematic diagram of an ultrasonic sensor system according to a first exemplary embodiment is shown;

[0065] Figure 2 A schematic diagram of an ultrasonic sensor system according to a second exemplary embodiment is shown;

[0066] Figure 3 A schematic diagram of a vehicle having a plurality of ultrasonic sensor systems according to a third exemplary embodiment is shown;

[0067] Figure 4 The steps of a method for performing test operations according to an exemplary embodiment are shown;

[0068] Figure 5 A three-dimensional plot of an exemplary characteristic diagram of an ultrasonic sensor is shown; and

[0069] Figure 6 A two-dimensional diagram of another exemplary characteristic of an ultrasonic sensor in which measurement points are input is shown.

[0070] Unless otherwise specified, the same or functionally equivalent elements in the figures are given the same reference numerals. Detailed Implementation

[0071] Figure 1A schematic diagram of an ultrasonic sensor system 1 according to a first exemplary embodiment is shown. The ultrasonic sensor system 1 is formed by at least a portion of an ultrasonic sensor 2 and a control device 3. The control device 3 may be, for example, a motor vehicle (…). Figure 3 11 in the middle; Figure 1 Electronic control unit (ECU) (not shown in the image).

[0072] exist Figure 1 The schematic diagram schematically shows the external shape of the housing of the ultrasonic sensor 2, and this diagram should be understood as being essentially purely functional. Figure 1 The ultrasonic membrane 4, represented as a membrane pot, is attached to... Figure 1 The ultrasonic sensor 2 is located on the lower side of its housing. A piezoelectric element 5 (an example of an acoustic transducer element) is attached (e.g., bonded) to the interior of the ultrasonic diaphragm 4. The piezoelectric element 5 is electrically connected to a coupling circuit 6. The coupling circuit is used for impedance matching. The arrangement of the ultrasonic diaphragm 4, the piezoelectric element 5, and the coupling circuit 6 is an example of an electroacoustic transducer arrangement 7.

[0073] The control unit 8, disposed in the housing of the ultrasonic sensor 2, is configured to apply an analog electro-oscillation signal to the electro-acoustic transducer arrangement 7 and capture the analog electro-oscillation signal applied to the control unit 8 by the electro-acoustic transducer arrangement.

[0074] The control device 3, located outside the ultrasonic sensor 2, includes a measurement control device 9 and a test control device 10.

[0075] During the measurement operation of the ultrasonic sensor 2, the measurement control device 9 exchanges control signals with the control unit 8 inside the sensor, preferably digital signals. Specifically, the measurement control device 9 can cause the control unit 8 to apply electrical control signals, particularly analog electrical control signals, and more particularly oscillating electrical control signals, to the electroacoustic transducer arrangement 7. The control signals excite the ultrasonic diaphragm 4 to oscillate via the piezoelectric element 5, thereby emitting ultrasonic waves. The measurement control device 9 then causes the control unit 8 to capture the electrical detection signal provided by the electroacoustic transducer arrangement 7 within a predetermined time period. When ultrasonic waves reflected from the environment are incident on the ultrasonic diaphragm 4 and cause the diaphragm to vibrate, the piezoelectric element 5 generates an echo signal (echo signal pulse) in the electrical detection signal. The detection signal is captured by the control unit 8 inside the sensor and preferably transmitted to the measurement control device 9 in digital form. The measurement control device 9 evaluates the detection signal captured in this way, identifies the echo signal, and uses the time difference between the emission of the ultrasonic signal and the appearance of the echo signal, along with the known speed of sound, to determine the distance to obstacles in the environment of the ultrasonic sensor 2.

[0076] The electroacoustic transducer arrangement 7 can be understood as an electrical arrangement with resistive, capacitive, and inductive characteristics. If these characteristics change, especially due to the aging effect of the piezoelectric element 5 or due to contamination, mismatches may occur in the control of the electroacoustic transducer arrangement 7 and / or the capture of the detection signals from the electroacoustic transducer arrangement 7, which may impair measurement quality.

[0077] Therefore, during the testing operation of the ultrasonic sensor 2, the test control device 10 of the control device 3 executes... Figure 4 The steps are illustrated schematically. (Combined) Figure 4 refer to Figure 1 .

[0078] In step S1, the measurement control device 10 exchanges control signals with the control unit 8 inside the sensor, preferably digital signals. In particular, the test control device 10 can cause the control unit 8 inside the sensor (in this case, an example of a "test device") to apply electrical test signals to the electroacoustic transducer arrangement 7, particularly analog electrical test signals, and more particularly oscillating electrical test signals.

[0079] When a test signal is applied to the electroacoustic transducer arrangement 7 in this manner, the test control device 9 captures in step S2 a signal, preferably a digital signal, transmitted by the control circuit 8 (“test device”) inside the sensor, which represents an electrical response signal from the electroacoustic transducer arrangement 7 to the application of the test signal, preferably an analog electrical response signal, more preferably an oscillating electrical response signal.

[0080] In step S3, the test control device 10 captures the characteristic variables of the electrical response signal.

[0081] In this case, the test signal can be a constant current signal (an AC signal with a constant current amplitude), and the electrical response signal can accordingly be a voltage signal that appears when the test signal is applied to the electroacoustic transducer arrangement 7. In this case, the captured characteristic variables are the voltage amplitude and optional phase angle of the electrical response signal.

[0082] However, the test signal can also be a constant voltage signal, and the corresponding electrical response signal can be a current signal. In this case, the captured characteristic variables can include the current amplitude and optional phase angle of the electrical response signal.

[0083] According to the proposal, in this case, the frequency and amplitude of the test signal are varied. This means that multiple measurement points operate at multiple different frequencies and amplitudes, and corresponding characteristic variables are captured at each measurement point.

[0084] The following will refer to Figure 5 and 6To explain in more detail the advantages and nuances of changing the frequency and amplitude; first, to describe... Figure 1 A structural alternative to the existing layout.

[0085] Figure 2 A schematic diagram of an ultrasonic sensor system 1 according to a second exemplary embodiment is shown. In the second exemplary embodiment, the functions of the measurement control device 9, the test control device 10, and the electroacoustic transducer arrangement 7 (coupled circuit 6, ultrasonic diaphragm 4, and piezoelectric element 5) are the same as in the first exemplary embodiment, but the measurement control device 9 and the test control device 10 are formed as part of the control unit 8 inside the sensor, rather than as part of the external control device 3.

[0086] Accordingly, in the second exemplary embodiment, the external control device 3 does not form part of the proposed ultrasonic system 1; instead, the ultrasonic system 1 in the second exemplary embodiment is entirely implemented by the ultrasonic sensor 2.

[0087] Accordingly, there is no need to exchange digital control signals with the control device 3 for performing measurement and testing operations. Consequently, only the measurement results of distance measurement and / or the status information determined from the captured characteristic variables can be transmitted to the control device 3 via the ultrasonic sensor 2; furthermore, the captured characteristic variables can be used internally by the sensor to improve the control of the electroacoustic transducer arrangement 7 during measurement operations.

[0088] The control unit 8 inside the sensor can be, in particular, an application-specific integrated circuit (ASIC) arranged on a printed circuit board (not shown) within the housing of the ultrasonic sensor 2.

[0089] Figure 3 A schematic diagram of a vehicle having multiple ultrasonic sensor systems 2 and control devices 3 according to a third exemplary embodiment is shown. The ultrasonic sensors 2 are arranged along the left-hand side, the right-hand side, and along the front and rear bumpers of the vehicle 11.

[0090] The third exemplary embodiment can be combined with the first and second exemplary embodiments. In other words, according to a variant, Figure 3 Each ultrasonic sensor 2 shown may have an integrated test control device 10. Figure 2 ), and therefore can represent ultrasonic sensor system 1 ( Figure 2 Accordingly, the vehicle 11 shown may have, for example, twelve independent ultrasonic sensor systems 1 ( Figure 2 The control device 3 can use the ultrasonic sensor system 1. Figure 2 It can be used to measure the vehicle's environment and the information obtained can be used to provide driving or parking assistance functions.

[0091] According to another variation, the proposed test control device 10 can be provided in the control device 3 of vehicle 11. Figure 1 ) and optional measurement and control equipment 9 ( Figure 1 Therefore, multiple ultrasonic sensors 2 and control device 3 can together form an ultrasonic sensor system 1 having multiple ultrasonic sensors 2. Figure 1 In this case, the test control device 10 of control device 3 ( Figure 1 The function of ) only needs to be configured once, and the test control device 10 ( Figure 1 ) can be used to centrally evaluate the arrangement of electroacoustic transducers 7 ( Figure 1 All captured characteristic variables can be taken into account when controlling measurement operations.

[0092] Figure 5 A three-dimensional diagram of an exemplary characteristic feature of an ultrasonic sensor is shown. Refer to [reference needed] if necessary. Figure 5 as well as Figure 1 and Figure 2 .

[0093] Figure 5 The characteristic diagram 13 consists of measurement points (not individually labeled due to their large number), which were captured by the ultrasonic sensor system 1 during a very comprehensive test operation. The frequency of the constant current test signal is plotted along the axis labeled "x", the amplitude of the current intensity of the constant current test signal is plotted along the axis labeled "y", and the amplitude of the voltage of the captured response signal is plotted along the axis labeled "z".

[0094] exist Figure 5 As can be seen in characteristic graph 13, there are two peaks 12, at which the amplitude of the characteristic graph increases sharply. It can also be seen that peaks 12 show a significant dependence on amplitude—their frequency positions shift to lower frequencies as the amplitude increases. These nonlinearities are caused by the inherent boundary effects in the piezoelectric element 5.

[0095] The central idea of ​​the proposed solution is that the electrical characteristic variables of the ultrasonic sensor 2 can be captured better if the capture is performed not only at different frequencies, but also at different amplitudes, especially at amplitudes that are actually related to the measurement operation of the ultrasonic sensor.

[0096] However, capture Figure 5 The entire characteristic diagram shown in Figure 13 requires changing both the frequency and amplitude of the test signal, each varying across the entire range of their values ​​in all possible combinations, and consequently requiring numerous measurements and a significant amount of time and energy. However, it is desirable to perform the test operation "online," i.e., without interruption or any significant disruption during the measurement process.

[0097] Therefore, refer to Figure 6 (also refer to) Figure 1 and Figure 2 The preferred method for interpreting and capturing the electrical characteristic variables of the electroacoustic transducer arrangement 7 can be provided by the test control device 10 in an exemplary embodiment. Figure 1 , 2 )accomplish.

[0098] Figure 6 A two-dimensional diagram of another exemplary characteristic of the ultrasonic sensor 2 is shown in Figure 13. Figure 6 In, such as Figure 5 Similarly, the frequency of the test signal is plotted along the "x" axis, and the amplitude of the test signal is plotted along the "y" axis. The amplitude of the response signal is determined by... Figure 6 The shadows in the diagram represent the signal amplitude; the darker the shadow, the higher the amplitude of the response signal. Specifically, in a diagram similar to... Figure 5 The theoretical and / or complete characteristics of the electroacoustic transducer arrangement determined through numerous experiments are shown in Figure 13. Figure 6 It is shown in shaded areas.

[0099] It should be noted that during the measurement operation, scanning can occur within a defined frequency range; that is, the measurement operation does not necessarily occur exactly at one frequency and one amplitude, but can advantageously occur along... Figure 6 The characteristic curve (not shown) in Figure 13 occurs.

[0100] Figure 6 Measurement points 14 and 15 of the characteristic graph are also shown, which are actually captured by the test control device 10 according to an exemplary embodiment during the test operation.

[0101] This means that during the test operation, the test control device 10 changes the frequency of the test signal in a way that makes... Figure 6 Multiple individual frequency support points at the frequencies of the measurement points 14 and 15 shown are passed one after another. In this case, exactly one measurement point is captured for each frequency, and for each such measurement point, the amplitude is selected depending on the frequency. In this case, the amplitude is selected (changed) in such a way that during the frequency scan of the measurement operation, the corresponding amplitude is related to the amplitude of the control signal at the corresponding frequency.

[0102] According to an exemplary embodiment, only the measurement point marked as 14 or only the measurement point marked as 15 is captured, and substantially corresponds to the point on the operating curve of the control signal during the measurement operation.

[0103] However, according to a particularly preferred exemplary embodiment, both measurement point 14 and measurement point 15 are captured, and the operating curve of the control signal amplitude can be obtained through a characteristic graph between the paths defined by measurement points 14 and 15. That is, measurement points 14 and 15 are selected in such a manner that, for every two adjacent measurement points 14 and 15, a measurement point 15 is selected at the lower limit of the amplitude range, and a second measurement point 16 is selected at the upper limit of the amplitude range, the amplitude range being centered on the amplitude of the control signal during the measurement operation, for example, at one of the frequencies or at the midpoint between two frequencies. Figure 6 When the test signal has only one frequency scan, this results in the first path 14 and the second path 15 through the characteristic curve, which together define a two-dimensional band through the characteristic curve. Therefore, the upper and lower limits of the electrical characteristic variables related to the measurement operation can be estimated in a particularly realistic way.

[0104] also, Figure 6 A particularly preferred exemplary embodiment is shown, wherein the measurement points in the first frequency range 16 are selected to be more distant than the measurement points 14, 15 in the second frequency range 17 near peak 12, where the gradient of the amplitude of the response signal is lower in the first frequency range and higher near peak 12. Accordingly, the number of points to be captured during the test operation can be further reduced, particularly in range 16.

[0105] Based on the above measurements, it is therefore advantageous to realistically estimate the characteristics of a two-dimensional characteristic plot of the amplitude of the response signal using only a few individual measurements at measurement points 14 and 15, specifically selected based on frequency, within the range relevant to the measurement operation. Therefore, the characteristic plot or characteristic variables can be rapidly captured at measurement points 14 and 15, which can be performed, for example, between two measurement cycles of the measurement operation without interrupting the measurement operation.

[0106] Various methods have been envisioned for evaluating the characteristic variables captured in this manner (the amplitude and possible phase angle of the electrical response signal that appears when the electrical test signal is applied to the measurement points 14 and 15) using the test control device 10.

[0107] For example, the height of peak 12 ( Figure 5 , 6 ), frequency position of peak 12 ( Figure 5 , 6 The ratio of peak heights to each other can vary during the operation of the ultrasonic sensor 12. The specified parameters of peak 12 can also be easily determined using a simple test control device 10, such as an application-specific integrated circuit (ASIC) 8. Figure 2 ) or vehicle control equipment (ECU) 3 ( Figure 1The test control device 10 can determine the degree of change in peak height or position relative to a reference state, and can use this degree of change to evaluate the state of the ultrasonic sensor 10. If the state of the ultrasonic sensor 2 is determined to be faulty, then, for example in Figure 3 In the exemplary embodiment shown, the ultrasonic sensor 2 can be excluded from the environmental measurements of the control device 3 (and is no longer considered). The control device 3 can output appropriate warning information to the driver or maintenance personnel.

[0108] However, it is also conceivable that, based on the determined peak position of the change, instead of identifying the fault state, the measurement operation (distance measurement) is adjusted.

[0109] Therefore, it is conceivable that the test control device 10 provides the measurement control device 9 with an evaluation of the captured characteristic variables (e.g., information regarding the shift position and / or height of peak 12), and depending on this, the measurement control device 9 causes the control unit 8 of the ultrasonic sensor 2 to, for example, increase the amplitude of the control signal during measurement operation to adjust the frequency position or frequency range of the control signal scan during measurement operation, amplify the detection signal during measurement operation, or adjust the threshold parameter used to capture the echo signal in the detection signal. Accordingly, the measurement control device 9 can perform distance measurement based on multiple characteristic variables captured by the test control device 10. Therefore, it is advantageous to maintain high measurement quality over longer operating cycles even if the electrical characteristics (e.g., resistance, inductance, and / or capacitance characteristics) of the electroacoustic transducer arrangement 7 change over time.

[0110] It is also conceivable that, in addition to the amplitude of the response signal as another characteristic variable, the test control device 10 also captures the phase angle of the response signal relative to the phase angle of the test signal as another characteristic variable, and incorporates this characteristic variable into the evaluation of the state of the ultrasonic sensor 2 and / or into the adjustment of the measurement operation of the measurement control device 9. In particular, the inductance and capacitance characteristics of the electric transducer arrangement 7 can be captured and evaluated based on the phase angle. The information obtained in this way can also be used, for example, to adjust the parameters of the resonant circuit included in the coupling circuit 6, thereby improving the impedance matching with the impedance of the electric transducer arrangement 7 at the relevant frequency and amplitude of the control signal.

[0111] The measures described above for reporting erroneous states of the ultrasonic sensor 2 and / or for adjusting measurement operations are advantageously performed using characteristic variables that are captured at the amplitude of a test signal, which corresponds to or is related to the amplitude of a control signal at its respective relevant frequency during the measurement operation, and therefore can have higher correlation or quality than characteristic variables captured at low or other amplitudes or constant amplitudes of the test signal.

[0112] Although the invention has been described based on exemplary embodiments, it can be modified in many ways.

[0113] The piezoelectric element 5 is described in the exemplary embodiment; however, the electroacoustic transducer arrangement 7 may also include other acoustic transducers based on the operating principles of mechanical capacitance, mechanical resistance, magnetostriction or electrostriction.

[0114] List of reference numerals

[0115] 1. Ultrasonic sensor system

[0116] 2. Ultrasonic sensor

[0117] 3. Control equipment

[0118] 4. Ultrasonic membrane

[0119] 5. Piezoelectric elements (sound transducer elements)

[0120] 6. Coupling circuit

[0121] 7. Electroacoustic transducer arrangement

[0122] 8. Control unit inside the sensor (test equipment)

[0123] 9. Measurement and control equipment

[0124] 10 Test control equipment

[0125] 11 Motor vehicles

[0126] 12 peaks

[0127] 13. Characteristic Diagram

[0128] 14 measurement points, first path

[0129] 15 measurement points, second path

[0130] 16 Low gradient frequency range

[0131] 17 High gradient frequency range

[0132] The axes of the x, y, z graph

[0133] S1-S3 Method Steps

Claims

1. An ultrasonic sensor system (1) for a motor vehicle (11), comprising: An ultrasonic sensor (2) having an electroacoustic transducer arrangement (7) and an electrical testing device (8), the electroacoustic transducer arrangement (7) being used to generate and detect ultrasonic waves, and the electrical testing device (8) being configured to output an electrical test signal to the electroacoustic transducer arrangement (7) and capture an electrical response signal from the electroacoustic transducer arrangement (7) to the electrical test signal, and A test control device (10) is configured to use the electrical test device (8) to capture characteristic variables of the electrical response signal, while simultaneously changing the frequency and amplitude of the electrical test signal at multiple measurement points. Specifically, for multiple different frequencies within the frequency range, each of the multiple measurement points includes exactly one measurement point. Specifically, the amplitude of the corresponding measurement point is selected based on the frequency of the measurement point. Furthermore, among the amplitudes of every two measurement points at adjacent frequencies within the frequency range, one amplitude is selected at the lower limit of the amplitude range chosen based on the adjacent frequencies, and another amplitude is selected at the upper limit.

2. The ultrasonic sensor system according to claim 1, The electrical test signal is a constant current signal, and the corresponding characteristic variables include the voltage amplitude and / or phase angle of the response signal at the corresponding measurement point under the frequency and amplitude of the electrical test signal.

3. The ultrasonic sensor system according to claim 1 or 2, During distance measurement, the plurality of measurement points of the test signal are selected as operation points corresponding to the control signals of the ultrasonic sensor (2).

4. The ultrasonic sensor system according to claim 1, in, The plurality of measurement points in the frequency range are selected to be closer together in the first frequency portion (17) than in the frequency portion (16), in the first frequency portion (17), a high gradient of the characteristic variable to be captured is determined during a previous test of the electroacoustic transducer arrangement, and in the frequency portion (16), a gradient lower than the high gradient is determined.

5. The ultrasonic sensor system according to claim 1 or 2, in, The test control device (10) is configured to report the status of the electroacoustic transducer arrangement (7) to the control device (3) of the motor vehicle (11) based on a plurality of characteristic variables captured by the test control device (10).

6. The ultrasonic sensor system according to claim 1 or 2, It also includes a measurement control device (9) configured to excite the electroacoustic transducer arrangement (7) to emit ultrasonic waves by applying an electrical control signal, and to perform distance measurement by subsequently capturing and evaluating an electrical detection signal from the electroacoustic transducer arrangement (7). The measurement control device (9) is configured to perform distance measurement based on a plurality of characteristic variables captured by the test control device (10).

7. The ultrasonic sensor system according to claim 1 or 2, The ultrasonic sensor (2) includes the test control device (10).

8. A motor vehicle (11) having at least one ultrasonic sensor system (1) according to any one of claims 1 to 7.

9. A method for operating an ultrasonic sensor system (1) for a motor vehicle (11), the ultrasonic sensor system comprising an ultrasonic sensor (2) having an electroacoustic transducer arrangement (7) for generating and detecting ultrasonic waves, and an electrical testing device (8), the ultrasonic sensor system further comprising a test control device (10), wherein the method comprises the following steps: The test equipment (8) outputs an electrical test signal to the electroacoustic transducer arrangement (7); The electrical response signal is captured from the electroacoustic transducer arrangement (7) by the test equipment (8); as well as The test control device (10) captures the characteristic variables of the electrical response signal at multiple measurement points, while simultaneously changing the frequency and amplitude of the electrical test signal. Specifically, for multiple different frequencies within the frequency range, each of the multiple measurement points includes exactly one measurement point. Specifically, the amplitude of the corresponding measurement point is selected based on the frequency of the measurement point. Furthermore, among the amplitudes of every two measurement points at adjacent frequencies within the frequency range, one amplitude is selected at the lower limit of the amplitude range chosen based on the adjacent frequencies, and another amplitude is selected at the upper limit.

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