Vibronial measuring device and method for signal processing in such a measuring device

Abstract

The present invention describes a vibronic measuring device (2), in particular a level sensor (2) for determining and / or monitoring at least one process variable of a medium (3) in a container (1), comprising at least one mechanically vibrating unit (40), at least one drive and receiver unit (31) for exciting the mechanically vibrating unit (40) to mechanical vibrations by means of an electrical excitation signal SA and for receiving and converting mechanical vibrations into an electrical received signal SE, and at least one control and evaluation unit (30) for controlling and / or regulating the vibration excitation and for evaluating the received signal SE with respect to the process variable, wherein the vibronic measuring device (2) comprises at least one vibration sensor (20) which is coupled to the vibronic measuring device (2) in such a way that vibrations are transmitted from the measuring device (2) to the vibration sensor (20).wherein a sensor signal SS can be tapped from the vibration sensor (20), characterized in that the vibronic measuring device (2) has an analysis unit (32) which is connected to the control and evaluation unit (30), wherein the electrical received signal SE and the sensor signal SS are supplied to the analysis unit (32) as input signals, the analysis unit (32) is designed as a unit for self-learning analysis of the input signals supplied to it, and the analysis unit (32) transmits at least one reliability information for the electrical received signal SE to the control and evaluation unit (30), wherein.

Description

The present invention relates to a vibronic measuring device according to the preamble of claim 1 and to a method for signal processing in such a vibronic measuring device according to the preamble of claim 10.Vibration sensors, also referred to as vibronic sensors or vibration limit sensors, having piezoelectric transmitting and / or receiving devices are known from the prior art. Piezoelectric transmitting and / or receiving devices are used as transmitting and / or receiving devices in vibration sensors, which are frequently used as limit level sensors in fill level measurement technology. Such piezoelectric transmitting and / or receiving devices are frequently also referred to as a drive.Vibration sensors according to the present application, in particular vibration limit switches for liquids and bulk materials, operate according to the principle of resonant frequency displacement and / or emit a vibration amplitude. The vibration sensor vibrates at a different resonance frequency and amplitude depending on the state of coverage, density and temperature of the medium. The amplitude of the resonant frequency is dependent on the viscosity of the medium. The frequency shift is dependent on the density and temperature of the medium. For monitoring the limit level, such sensors are mounted in containers at the level of a fill level to be monitored and output status information on the basis of the above parameters. In concrete terms, information can be picked up at the sensors as to whether the sensor has been covered or uncovered, or as to whether a fill level of the medium has reached (covered) or has fallen below (uncovered) the fill level to be monitored.Typically, the vibration sensor has a membrane which can be excited to produce a vibration by means of such a drive, by means of which membrane a mechanical vibrator arranged on the membrane can be excited to produce a vibration as a mechanical oscillatable unit. Depending on a level of coverage of the mechanical oscillator with a filling material and depending on the viscosity of this filling material, the mechanical oscillator oscillates with a characteristic frequency, which is detected by the vibration sensor and can be converted into a measurement signal.DE 10 2012 101 667 A1 relates to a vibronic measuring device for determining and / or monitoring at least one process variable of a medium in a container, having at least one mechanically oscillatable unit, having at least one piezoelectric drive and receiving unit for exciting the mechanically oscillatable unit to mechanical oscillations by means of an electrical excitation signal and for receiving and converting mechanical oscillations into an electrical received signal, and having at least one regulating and evaluating unit for regulating and / or controlling the oscillation excitation and for evaluating the received signal with respect to the process variable. The process variable is, for example, the fill level, in particular a limit level, the density, the viscosity or the flow rate of a liquid medium, or the fill level of a bulk material. The control and evaluation unit according to the disclosure in DE 10 2012 101 667 A1 is configured to control the vibrational excitation in such a way that the received signal is substantially undisturbed by the extraneous vibration and / or to suppress at least one frequency of extraneous vibration in the received signal when at least one extraneous vibration is present as a function of the frequency and / or the amplitude of the extraneous vibration.According to one embodiment of the method, the external vibration is detected at the aforementioned measuring device by interrupting the excitation of the mechanically oscillatable unit to oscillations and evaluating the received signal during the interruption. This is perceived as disadvantageous, since a continuous measurement is thus not possible.In an alternative embodiment of the method, the external vibration is detected by means of a vibration sensor which is arranged on the container, in or on the measuring device, or on a component connected to the container. Preferably, the vibration sensor is attached to the process port of the measuring device.In principle, the second alternative represents an improved configuration, since an interruption of the measurement can be avoided in this way. However, the reliability and safety of the detection of a spurious vibration with this system is still considered to be insufficient.Extraneous oscillations which are too close to the frequency of the fundamental mode of the excitation signal and / or of the useful signal of the vibronic measuring device cannot thus be reliably detected.Furthermore, the proposed solution of controlling the vibrational excitation by changing the excitation frequency, that the received signal is substantially undisturbed by the external vibration, is technically difficult to implement, since the resonant frequency of the mechanically oscillatable unit depends on its geometry and the medium surrounding the unit and cannot be changed by changing the excitation. Although the excitation of higher vibration modes is possible, in the case of extraneous vibration at or near the resonant frequency of the main mode, the amplitude of these higher vibration modes is so low that, in practice, signal evaluation is not possible, or is only possible to an inadequate extent.Further prior art is known from DE 10 2021 129 416 A1 and DE 10 2022 200 917 A1.It is the object of the present invention to provide a vibronic measuring device and a method for signal processing in a vibronic measuring device, which enables improved signal processing, in particular detection and preferably suppression of extraneous oscillations.This object is achieved by a vibronic measuring device having the features of claim 1 and by a method for signal processing in a vibronic measuring device having the features of claim 10. Advantageous further developments are the subject matter of the dependent patent claims and of the following description.A vibronic measuring device according to the invention for determining and / or monitoring at least one process variable of a medium in a container, having at least one mechanically oscillatable unit, having at least one drive and receiving unit for exciting the mechanically oscillatable unit to mechanical oscillations by means of an electrical excitation signal and for receiving and converting mechanical oscillations into an electrical received signal, has at least one regulating and evaluating unit for regulating and / or controlling the oscillation excitation and for evaluating the received signal with respect to the process variable. The vibronic measuring device further comprises at least one vibration sensor, which is coupled to the vibronic measuring device in such a way that vibrations are transmitted from the measuring device to the vibration sensor, wherein a sensor signal can be picked up at the vibration sensor. According to the invention, the vibronic measuring device has an analysis unit which is connected to the control and evaluation unit, wherein the analysis unit is supplied with the electrical received signal and the sensor signal as input signals, the analysis unit is designed as a unit for self-learning analysis of the input signals supplied thereto, and wherein the analysis unit transmits at least one item of reliability information for the electrical received signal to the control and evaluation unit.The vibronic measuring device according to the invention is thus capable of analyzing the input signals supplied to it, in the present case at least the received signal of the drive and receiving unit and the sensor signal of the vibration sensor, and generating a reliability information for the received signal in a self-learning manner. This reliability information can contain, in particular, a statement as to whether or to what extent an information about the process variable extracted from the received signal by the control and evaluation unit is to be evaluated as reliable.The vibronic measuring device is enabled for this purpose by the analysis unit, which is preferably designed as an AI unit trained by means of suitable training data. The AI unit can preferably be designed as an artificial neural network to which different input data are supplied depending on the embodiment of the present invention, a statement about the reliability of the input data being determined on the basis of this input data.The artificial neural network can be designed, for example, as a multi-layer perceptron, i.e. feed forward neural network.Vibration sensors according to the present invention may be vibration sensors, acceleration sensors and also inertial measurement units. To detect the six possible kinematic degrees of freedom, an inertial measurement unit has three acceleration sensors (translation sensors) which are each mutually orthogonal for detecting the translatory movement in the x, y and z directions, and three rotation rate sensors (gyroscopic sensors) which are aligned orthogonally with respect to one another for detecting rotational movements about the x, y and z axes.Both the drive and receiving unit and the acceleration sensor are acted upon by a superposition of vibrations that result from the measurement itself, i.e. the vibration that is caused by the drive unit in the mechanically oscillatable unit, and extraneous vibrations that couple, for example, via the container to the vibronic measuring device. The receiving unit "sees" this superposition, however, through the mechanical filter of the mechanically oscillatable unit and can therefore only detect a direction of the resulting oscillation to a limited extent. The vibration sensor, on the other hand, can record the vibration unfiltered and thus derive additional information.Systems are preferred which can measure the direction, the magnitude and the frequency of accelerations acting on the sensor, so that as much information as possible about possible extraneous oscillations which can influence a measurement is obtained. The vibration sensor can be constructed, for example, as a three-axis accelerometer or as a gyroscope in MEMS technology. By means of the additional information about the direction and the amount of acceleration, extraneous oscillations can be better classified and evaluated.The analysis unit according to the present invention is designed such that the analysis of the input signals of the analysis unit takes place within the vibronic measuring device, so that there is no dependence on a connection to the cloud, i.e. in particular on a network connection. Further advantages of signal processing directly in the measuring device consist, for example, in a shorter reaction time of more simply ensuring data protection, since the raw data do not leave the measuring device.In a preferred embodiment, the electrical received signal and / or the sensor signal are supplied to the analysis unit in the time domain and in the spectral domain. This means that either the received signal or the sensor signal or the received signal and the sensor signal are supplied to the analysis unit both in the time domain and in the spectral domain, i.e. after a spectral analysis. Depending on the desired information, it can be determined better from the signals in the time domain or in the spectral range. Temporal sequences can be better recognized, for example, in the time domain, while different frequency components of the signals are better recognized in the spectral range.The transfer of the signals from the time to the spectral range takes place by spectral analysis. The usual algorithm for this purpose has been the Fourier transformation and in particular the fast Fourier transformation (FFT).As a further relevant signal, a temperature signal can be fed as an input signal to the analysis unit. The temperature has a substantial influence on the natural frequency of the mechanically oscillatable unit and can be determined without great effort. Many vibronic measuring devices therefore already have a temperature sensor or another type of temperature determination, so that the temperature can also be used in the further signal processing in the analysis unit.Optionally, the electrical excitation signal can also be supplied as an input signal to the analysis unit. The electrical excitation signal can also be supplied in the time domain and / or in the spectral range.The analysis unit can be designed to detect periodic events. There are different AI units which, on account of the algorithms used and / or on account of the basic architecture of the AI, are particularly well suited for different tasks. Temporally recurring patterns can be recognized particularly well, for example, by so-called "recurrent neural networks" or "RNNs" (recurrent neural networks). An AI constructed in this way can, for example, detect periodically recurring events which interfere with or influence a measurement and thus influence the measurement system positively, for example. If the system detects, for example, that a filling process by a pump then running and a flow of flowing medium regularly interferes with the measurement, then a measurement can be carried out, for example, directly before the filling process, so that an uncorrupted measured value can still be determined.In an additional or alternative embodiment, the analysis unit is designed to be particularly suitable for detecting frequency patterns. Complex patterns or structures can be recognized particularly well here by convolutional neural networks (CNN). An embodiment for detecting frequency patterns can be provided by a convolutional neural network which is designed as an additional or alternative neural network instead of or in addition to other AI units or within an AI unit.By analyzing frequency patterns, it is possible to detect causes of extraneous vibrations. On the basis of the detection of the causes, suitable measures can be taken to reduce an influence of the extraneous vibrations on the measurement result, i.e. in particular a switching decision of the vibronic sensor. Suitable measures for reducing the influence of extraneous vibrations can be, for example, an adaptation of the signal filtering, an increase in the excitation amplitude or a change in the excitation frequency in such a way that another eigenmode of the mechanically oscillatable unit is excited. Additionally or alternatively, changing a switching delay may have a positive impact. In this way, sporadic erroneous results could be suppressed. The adaptation of the filtering can also comprise, for example, the intermediate connection of an additional filter. For example, in certain situations it may be useful to calculate a moving average value over a predefinable number of measured values. By such averaging, individual outliers in the measured values can likewise be suppressed.The analysis unit can furthermore be suitably designed to generate and output a warning signal based on the analysis if a quality of the useful signal is too low and thus the probability of a misinterpretation is too high. In this way, the input signal can be discarded in certain situations, so that errors are avoided. In particular, if measures for reducing the influence of the extraneous vibrations on the useful signal are exhausted, it may be useful to output such a warning message. The warning message can be output in addition to or as an alternative to the output signal.The output signal obtained can thus be discarded and a warning signal instead be output, or a warning is output in addition to the output signal, which warning identifies the output signal as unreliable.In a further development, the analysis unit can transmit to the control and evaluation unit an adjustment signal for adjusting at least one adaptive filter for the received signal. This can be useful in particular if a source of extraneous vibrations can be identified and generates characteristic frequencies which can be filtered well.In one variant, the analysis unit is designed such that it recognizes, classifies, and makes available to the control and evaluation unit a classifier that identifies the respective class of the recognized event. Such a classification can help define countermeasures for different classes of events, wherein the events of a class have the same or at least similar properties.The control and evaluation unit can be designed, for example, in such a way that it adjusts a measurement rate and / or signal processing, in particular a filtering, on the basis of the classification. Various possibilities for this have already been described above.A method according to the invention for signal processing in a vibronic measuring device according to the above description is characterized in that the electrical received signal and the sensor signal are supplied to the analysis unit as input signal and the analysis unit transmits at least one item of reliability information for the electrical received signal to the control and evaluation unit, wherein the analysis unit self-learning analyzes the input signals supplied to it.In a development of the method, the electrical received signal and / or the sensor signal in the time domain and in the spectral domain are supplied to the analysis unit.In addition, a temperature signal can be supplied to the analysis unit as a further input signal.In one embodiment of the method, the analysis unit carries out a recognition of periodic events.In a further embodiment of the method, the analysis unit additionally or alternatively carries out a recognition of frequency patterns.It is preferred if the analysis unit generates and outputs a warning signal based on the analysis, in particular if a quality of the useful signal is too low.In one embodiment, the analysis unit passes on a signal for setting at least one adaptive filter for the received signal to the control and evaluation unit. This signal achieves optimum setting of the adaptive filter, so that the useful signal can be better extracted from the received signal.In a further embodiment, the analysis unit recognizes and classifies events causing external vibrations and outputs information about them. For example, a classifier, i.e., a value characterizing the class of the detected event, may be output. The classifier can then be further processed by the control and evaluation unit and / or a presetting of the adaptive filter can be used for filtering the received signal.The control and evaluation unit can also adapt a measurement rate and / or a signal processing, in particular a filtering, on the basis of the classification and / or the type of an event.The present invention is explained in more detail below with reference to the attached figures. The following are shown: FIG. 1 shows a measuring arrangement with a vibronic measuring device according to the prior art, designed as a limit level sensor, FIG. 2 shows an exemplary embodiment of a vibronic measuring device designed as a limit level sensor according to the present application, and FIG. 3 shows an exemplary embodiment of an analysis unit as can be used in the limit level sensor according to FIG. 2.FIG. 1 shows a typical application of a vibronic measuring device 2 as vibronic limit level sensor 2 according to the prior art.The limit level sensor 2 is installed as an overfill protection in a tank 1. Filling of the tank 1 via an inlet 4 aarranged in an upper region of the tank 1 is effected via a pump 5 aand is controlled via the limit level sensor 2. If the limit level sensor 2 detects a medium 3, the pump 5a is switched off in order to prevent the tank 1 from overflowing. The limit level sensor 2 uses here a piezoelectric drive as an electromechanical transducer, which acts as a drive and reception unit 31. Alternatively, electromagnetic transducer units are also possible. A mechanically oscillatable unit 40 is excited at its resonant frequency via the electromechanical transducer. The sensor can detect the presence of a medium 3 via the resonant frequency and the amplitude of the oscillation.Emptying of the tank 1 takes place via an outlet 4 barranged in a lower region, close to a bottom of the tank 1, is effected via a second pump 5 b.If vibrations of the pump 5a are transmitted to the limit level sensor 2, it may happen in unfavourable cases that the limit level sensor 2 detects these vibrations as a measurement signal. This can result in a malfunction of the limit level sensor 2. If the vibrations of the pump 5a are in a range which the limit level sensor 2 would recognize as covered, an incorrect switching signal can be output. If the vibrations are in a range which the limit level sensor 2 would recognize as being uncovered, the exceeding of the limit level cannot be detected, which in the worst case results in an overfilling of the tank 1.FIG. 2 shows a limit level sensor 2 according to the present application.An analysis unit 32 is integrated in the limit level sensor 2, which analysis unit can detect extraneous vibrations. The analysis unit 32 is coupled to a vibration sensor 20, which is designed as an inertial sensor in the present exemplary embodiment. The vibration sensor 20 is arranged in the limit level sensor 2 in such a way that, on the one hand, it is mechanically decoupled from the mechanically oscillatable unit 40, but, on the other hand, it is mechanically coupled to a housing of the limit level sensor 2 in such a way that extraneous oscillations acting on the limit level sensor 2 can be detected as well as possible. The vibration sensor 20 is ideally arranged in the region of a process connection 35 of the limit level sensor 2, so that only the extraneous vibrations which act on the limit level sensor 2 are evaluated by the vibration sensor 20 as far as possible. Without mechanical decoupling, the oscillations of the mechanically oscillatable unit 40, which are generated by the drive unit 31, cannot be distinguished from extraneous oscillations.A mechanical decoupling is already achieved when the mechanical oscillations generated by the drive unit 31 for the measurement are significantly reduced, in particular with an amplitude reduced by a factor of 5, preferably by a factor of 10, applied to the vibration sensor 20. A complete mechanical decoupling is not possible due to the arrangement in the same housing.Further processing of the output signals of the analysis unit 32 takes place in the control and evaluation unit 30. The analysis unit 32 can also be integrated into the control and evaluation unit 30.A function of the analysis unit 32 is supported by integrated artificial intelligence in the present case. In this case, different functions for improving, stabilizing or adapting the measurement function of the control and evaluation unit 30 can be realized.In the present exemplary embodiment, the analysis unit 32 is supplied with the electrical received signal S E, the sensor signal S S and the electrical excitation signal S A as input signals in the time domain and also after a fast Fourier transformation in the spectral range. As a further input signal, a temperature signal T of a temperature sensor arranged adjacent to the mechanically oscillatable unit 40 is supplied to the analysis unit 32.As an output signal, the analysis unit 32 provides reliability information Z indicating a quality and reliability of the received signal S E filter parameters for setting an adaptive filter, and information about regularity of interference due to extraneous oscillations.Depending on the reliability information Z, this is identified as valid or unreliable by the control and evaluation unit 30. The setting of the adaptive filter enables an improvement in the reliability information Z. In the case of regularly recurring disturbances, a countermeasure can be initiated already in advance of the disturbance by the information about a regularity of the disturbance due to extraneous oscillations, for example an increase in the measurement rate can be carried out, the filter setting can be adapted and / or an influence on the intrinsic oscillation due to the extraneous oscillation can be reduced, for example by increasing an amplitude of the excitation signal S A, or excitation of a less or not influenced intrinsic oscillation of the mechanically oscillatable unit 40.Further functions are also conceivable. If the pump 5 ais not in continuous operation, but only sporadic, this can be detected by the AI. If the vibration of the pump 5 ais detected, the measurement rate of the limit level sensor 2 can then be increased in order to thereby detect reaching a maximum fill level more safely and quickly. In an alternative embodiment, it would also be conceivable for the measurement and pump 5 ato be controlled by a common control unit. In this scenario, pump and measurement times may alternate. Thus, it can be checked via the sensor in a pause of the pumping process whether it is allowed to continue pumping.FIG. 3 shows an exemplary embodiment of an analysis unit 32 as can be used in the limit level sensor 2 according to FIG. 2.The analysis unit 32 according to FIG. 3 has six signal inputs 301- 306 and four signal outputs 311- 314 in the simplified illustration shown in FIG. 3.At the first signal input 301, the excitation signal S A in the spectral range S AS is supplied to the analysis unit 32. The received signal S E is present at the second and third signal inputs 302, 303 in the time range S EZ and in the spectral range S ES. The sensor signal S S is present at the fourth and fifth signal inputs 304, 305 in the time and spectral ranges S SZ, S SS respectively. The temperature signal T of the temperature sensor is applied to the sixth signal input 306.The reliability information Z can be tapped at the first signal output 301. A classifier K for extraneous oscillations can be tapped at the second signal output 302. At the third signal output 303, a setting signal E for setting the adaptive filter can be tapped off and at the fourth signal output 304, a signal warning signal can be tapped off, which signal warning signal, in addition to the reliability information Z, represents a warning if the quality of the input signal falls below a threshold value in comparison with extraneous oscillations, for example in the sense of a signal to noise ratio.List of reference characters1 Container, tank 2 vibronic measuring device / limit level sensor 3 medium 4 a inflow 4 b outflow 5 apump 5 bpump 20 vibration sensor 30 regulating and evaluation unit 31 drive and receiving unit 32 analysis unit 40 mechanically oscillatable unit 301- 306 signal inputs 311- 314 signal outputs E setting signal K classifier S A excitation signal S E received signal S S sensor signal S SS sensor signal in the spectral range S SZ sensor signal in the time range T temperature signal W warning signal Z reliability information

Claims

Vibronic measuring device (2), in particular a limit level sensor (2) for determining and / or monitoring at least one process variable of a medium (3) in a container (1), having at least one mechanically oscillatable unit (40), having at least one drive and receiving unit (31) for exciting the mechanically oscillatable unit (40) to mechanical oscillations by means of an electrical excitation signal S A and for receiving and converting mechanical oscillations into an electrical receiving signal (S E), and having at least one regulating and evaluating unit (30) for regulating and / or controlling the oscillation excitation and for evaluating the receiving signal (S E) with respect to the process variable, wherein the vibronic measuring device (2) has at least one vibration sensor (20), which is coupled to the vibronic measuring device (2) in such a way that oscillations are transmitted from the vibronic measuring device (2) to the vibration sensor (20), wherein a sensor signal (S S) can be picked up at the vibration sensor (20), characterized in that the vibronic measuring device (2) has an analysis unit (32), which is connected to the control and evaluation unit (30), wherein the analysis unit (32) is supplied with the electrical received signal (S E) and the sensor signal (S S) as input signals, the analysis unit (32) is designed as a unit for self-learning analysis of the input signals supplied thereto, and the analysis unit (32) transmits at least one item of reliability information for the electrical received signal (S E) to the control and evaluation unit (30).Vibronic measuring device (2) according to claim 1, characterised in that the electrical reception signal S E and / or the sensor signal (S S) are supplied to the analysis unit (32) in the time range (S SZ) and in the spectral range (S SS).Vibronic measuring device (2) according to claim 1 or 2, characterised in that a temperature signal (T) is supplied as a further input signal to the analysis unit (32).Vibronic measuring device (2) according to one of the preceding claims, characterized in that the analysis unit (32) is designed to detect periodic events.Vibronic measuring device (2) according to one of the preceding claims, characterized in that the analysis unit (32) is designed to detect frequency patterns.Vibronic measuring device (2) according to one of the preceding claims, characterized in that the analysis unit (32) is suitably designed to generate and output a warning signal (W) based on the analysis if a quality of a useful signal extractable from the electrical received signal (S E) is too low.Vibronic measuring device (2) according to one of the preceding claims, characterized in that the analysis unit (32) of the regulating and evaluating unit (30) outputs a signal for setting at least one adaptive filter for the received signal (S E).Vibronic measuring device (2) according to one of the preceding claims, characterized in that the analysis unit (32) is designed in such a way that it recognizes and classifies events causing external vibrations and makes a classifier (K) available to the control and evaluation unit (30).Vibronic measuring device (2) according to one of the preceding claims, characterized in that the control and evaluation unit (30) is designed in such a way that it adjusts a measurement rate and / or a signal processing, in particular a filtering, on the basis of the classification of an event.Method for signal processing in a vibronic measuring device (2) according to one of the preceding claims, characterized in that the electrical received signal (S E) and the sensor signal (S S) are supplied to the analysis unit (32) as input signals and the analysis unit (32) transmits at least one item of reliability information (Z) for the electrical received signal (S E) to the control and evaluation unit (30), wherein the analysis unit (32) analyzes the input signals supplied to it in a self-learning manner.Method according to Claim 10, characterized in that the electrical reception signal (S E) and / or the sensor signal (S S) are fed to the analysis unit (32) in the time range (S SZ) and in the spectral range (S SS).Method according to claim 10 or 11, characterised in that a temperature signal (T) is supplied as a further input signal to the analysis unit (32).Method according to one of Claims 10 to 12, characterized in that the analysis unit (32) carries out a detection of periodic events.Method according to one of Claims 10 to 13, characterized in that the analysis unit (32) carries out a detection of frequency patterns.Method according to one of Claims 10 to 14, characterized in that the analysis unit (32) generates and outputs a warning signal (W) on the basis of the analysis if a quality of a useful signal extractable from the electrical reception signal (S E) is too low.Method according to one of Claims 10 to 15, characterized in that the analysis unit (32) of the regulating and evaluation unit (30) outputs a signal for setting at least one adaptive filter for the received signal (S E).Method according to one of Claims 10 to 16, characterized in that the analysis unit (32) recognizes and classifies events which cause external vibrations and outputs information about this, in particular a classifier.Method according to one of Claims 10 to 17, characterized in that the control and evaluation unit (30) adjusts a measurement rate and / or signal processing, in particular a filtering, on the basis of the classification and / or the type of an event.

Images