DE102017222656A1 - SENSOR AND SENSOR SYSTEM - Google Patents

Abstract

The invention relates to a sensor (10) having a sensor element (12) which is designed to vibrate in an operating state of the sensor with at least one predetermined oscillation frequency, wherein a sensor signal can be derived from the oscillations, and at least one resonator (14), which is designed to oscillate with a corresponding external excitation of the sensor with at least one resonator frequency which is adapted to one of the predetermined oscillation frequencies of the sensor element or to a further frequency of the sensor element.

Description

The invention relates to a sensor and a sensor system according to the independent claims, which are intended in particular for use in automotive technology, especially in vehicle dynamics control systems.

Control systems for ensuring a stable driving dynamic condition and for detecting the condition of safety systems in vehicles require accurate and reliable data, in particular the rate of rotation and acceleration of a vehicle, for reliable operation. To avoid erroneous system behavior of the control systems, the sensors used to detect the rate of rotation and acceleration are usually equipped with comprehensive monitoring measures, which are optimized especially for detecting sensor-internal defects. A detected error state of a sensor is to be forwarded to the sensor signal users sufficiently quickly so that undesired control interventions due to sensor errors can be avoided.

From the European patent application EP 1 249 371 A1 For example, a method for detecting rollover events in a motor vehicle is known, in which translational accelerations of the vehicle are taken into account in the evaluation of a rotation rate sensor signal in order to avoid malfunctions in the operation of the rotation rate sensor, which have been caused by extreme translational accelerations, for the false triggering of Restraining means for a rollover process lead.

The German patent application DE 10 2006 031 730 A1 relates to a method for fault diagnosis and correction of a sensor of a safety-critical system of a vehicle, in which, for fault diagnosis, the sensor is tested for a specified mode of operation by checking at least parts of the sensor specification and generating a fault diagnosis signal as a result of fault diagnosis, and the signal the sensor is corrected with a substitute value strategy, if the error diagnostic signal indicates a fault of the sensor.

The German patent DE 10 2007 037 298 B1 describes a method and an arrangement for checking a sensor signal. In this case, for checking a first sensor signal of a first sensor cluster with at least one first sensor, one or more physical measured variables in a first measuring range are detected by the first sensor cluster. By evaluating a second sensor signal of a second sensor cluster with at least one second sensor, it is determined whether a predetermined operating state exists, wherein one or more of the physical measured variables are detected in a second measuring range different from the first measuring range by the second sensor cluster. In the presence of one of the predetermined operating states is then detected on a presence or absence of a possible external interference on the first sensor signal.

The German patent DE 10 2007 046 982 B3 discloses a device for detecting an accident situation, in particular a collision of a vehicle with an obstacle and / or a rollover process, with a structure-borne sound receiving unit and with an evaluation unit, wherein the structure-borne sound receiving unit is arranged in the vehicle, that of a deformation of a body or of body parts the sound produced by the vehicle and / or the vibrations of the body parts generated by a deformation are transmitted to the structure-borne sound receiving unit, wherein the evaluation unit evaluates the detected sound and / or the detected vibrations to determine an accident situation of the vehicle, wherein the evaluation unit detects the detected sound and / or or the detected vibrations in the evaluation checks whether the detected sound and / or the detected vibrations of a particular waveform corresponds or correspond to be evaluated and / or considered as influencing signal information ,

The object of the present invention is now to propose an improved sensor and an improved sensor system.

It has been shown that external influences on a sensor can lead to a signal generated by the sensor often being only temporarily, ie limited in time, but not permanently disturbed or faulty, and therefore there is no actual defect of the sensor. For the operation of the sensor, the detection of such external influences may be advantageous since this can be used, for example, for the temporary deactivation of a use of the disturbed or faulty sensor signal. An idea on which the present invention is based is therefore to recognize such external influences on a sensor, which can cause disturbances or errors in the sensor output signal, by providing at least one resonator in addition to at least one sensor element of the sensor, which with appropriate external excitation can vibrate at least one resonator frequency. The at least one resonator frequency is in this case adapted to one of at least one predetermined oscillation frequency of the at least one sensor element or to a further frequency of the sensor element. By the resonator, it is possible to detect an external influence, which generates vibrations in a range by excitation of the at least one resonator, which are in the range of at least one predetermined oscillation frequency and therefore can affect the proper operation of the at least one sensor element. Such a sensor can be used, for example, in control systems to ensure a stable driving dynamic state and to detect the state of safety systems in vehicles. If an external influence on the sensor is detected, which can lead to a disturbance of the operating state of the sensor and to a faulty sensor signal, sensor signal processing, for example, can be temporarily suspended, so that no faulty sensor signal is used in a control system in which the sensor is used. is processed. Overall, this can create a sensor and a sensor system with improved robustness to external influences. A resonator frequency is understood here to mean a frequency at which a resonator oscillates with a corresponding external excitation. This may be a resonance frequency of a vibration element of a resonator.

According to one embodiment of the invention, a sensor is provided which comprises a sensor element which is designed to oscillate in an operating state of the sensor with at least one predetermined oscillation frequency and from whose oscillations a sensor signal is derived, and at least one resonator which is formed is to oscillate in the operating state of the sensor with at least one resonator frequency, which is adapted to one of the at least one predetermined oscillation frequency of the sensor element and / or to a further frequency of the sensor element.

Detection means may be provided which are designed to monitor the at least one resonator and to detect oscillations of the resonator in the region of the at least one resonator frequency. In particular, the detection means may be configured to generate at least one electrical signal for electronic processing by means of capacitive, piezoelectric and / or piezoresistive detection of the oscillations of the at least one resonator.

An evaluation circuit may be provided which is designed to process detected oscillations of the resonator in the region of the at least one resonator frequency and to generate an indicator signal as a function thereof. The evaluation circuit may in particular be designed to derive a parameter from detected oscillations and to compare the derived parameter with at least one threshold value and to generate the indicator signal if the detected deviation exceeds one or more threshold values. The evaluation circuit can also be designed to calibrate the at least one threshold based on a resonance behavior of the sensor element by setting the at least one threshold such that an external excitation of the sensor, which causes a vibration of the sensor element in the range of at least one predetermined oscillation frequency Threshold exceeded.

The sensor element may be a micromechanical rotation rate sensor having a first predetermined oscillation frequency and a second predetermined oscillation frequency, wherein the first and second predetermined oscillation frequencies are different. In particular, the sensor may have an additional first and a second micromechanical resonator, wherein the resonator frequency of the first micromechanical resonator is adapted to the first predetermined oscillation frequency and the resonator frequency of the second micromechanical resonator to the second predetermined oscillation frequency.

According to a further embodiment of the invention, a sensor system is provided which has at least one sensor according to the invention as described herein and sensor signal processing which is designed to process the sensor signal of the at least one sensor as a function of the at least one resonator frequency of the at least one resonator. In particular, the sensor signal processing may be configured to suspend processing of the sensor signal of the at least one sensor when the measurement signal at the at least one resonator frequency of the at least one resonator signals an oscillation at the at least one predetermined oscillation frequency of the sensor element.

Details of one or more embodiments of the invention are set forth in the following description and the accompanying drawings. Other features, advantages and applications of the invention will become apparent from the description, the drawings and the claims.

list of figures

• 1 ein erstes Ausführungsbeispiel eines Sensorsystems mit mehreren Sensoren und einem Sensor-externen Analysesystem zur Ermittlung eines Umweltstatus der Sensoren;
• 2 ein erstes Ausführungsbeispiel eines Drehratensensors mit einem Umweltstatus-Detektor;
• 3 ein zweites Ausführungsbeispiel eines Drehratensensors mit einem Umweltstatus-Detektor;
• 4 ein drittes Ausführungsbeispiel eines Drehratensensors mit einem Umweltstatus-Detektor;
• 5 ein viertes Ausführungsbeispiel eines Drehratensensors mit einem Umweltstatus-Detektor;
• 6 ein fünftes Ausführungsbeispiel eines Drehratensensors mit einem Umweltstatus-Detektor, das Implementierungsdetails einer MEMS-Zelle und der Verschaltung mit einer Signalauswertung zeigt;
• 7 ein sechstes Ausführungsbeispiel eines Drehratensensors mit einem Umweltstatus-Detektor;
• 8 ein siebtes Ausführungsbeispiel eines Drehratensensors mit einem Umweltstatus-Detektor; und
• 9 ein zweites Ausführungsbeispiel eines Sensorsystems mit mehreren Sensoren und einem Sensor-externen Analysesystem zur Ermittlung eines Umweltstatus der Sensoren.

The drawings show in

• 1 a first embodiment of a sensor system with a plurality of sensors and a sensor-external analysis system for determining an environmental status of the sensors;
• 2 a first embodiment of a rotation rate sensor with an environmental status detector;
• 3 a second embodiment of a rotation rate sensor with an environmental status detector;
• 4 a third embodiment of a rotation rate sensor with an environmental status detector;
• 5 A fourth embodiment of a rotation rate sensor with an environmental status detector;
• 6 a fifth embodiment of a rotation rate sensor with an environmental status detector showing implementation details of a MEMS cell and the interconnection with a signal evaluation;
• 7 a sixth embodiment of a rotation rate sensor with an environmental status detector;
• 8th a seventh embodiment of a rotation rate sensor with an environmental status detector; and
• 9 A second embodiment of a sensor system with a plurality of sensors and a sensor-external analysis system for determining an environmental status of the sensors.

DETAILED DESCRIPTION

In the following description, identical, functionally identical and functionally connected elements may be provided with the same reference numerals. Absolute values are given below by way of example only and are not to be construed as limiting the invention.

The present invention is intended in particular for use in automotive technology, especially in vehicle dynamics control systems. Hereinafter, sensor systems and sensors will be described as embodiments of the invention, which are suitable for use in such control systems, in particular rotation rate sensors. However, the invention is not limited to this application and rotation rate sensors, but can also be used in other applications with similar demands on the robustness and reliability of sensors and other sensors as rotation rate sensors such as linear acceleration sensors.

As already described in the introduction, in order to avoid a faulty behavior of a control system for the driving dynamics of an automobile, the recognition of a fault condition in the sensor (s) used in the control system is of particular importance. An error state of a sensor can be triggered on the one hand by a defect in the sensor itself, for example by undesired particles in micromechanical sensor elements (MEMS: micro-electro-mechanical system), or by interrupted electrical connections between a sensor element and an associated evaluation element. A unit that may be implemented, for example, by an Application Specific Integrated Circuit (ASIC). This error state is often provided in the form of an error status signal, for example by an error bit, the evaluation unit of the sensor and signals that the currently provided signal is untrustworthy.

On the other hand, a response of a monitoring unit provided for the detection of a fault condition of the sensor may also have causes outside of the sensor. Such causes are also referred to herein as external excitation of a sensor, since they can lead to the generation of unwanted sensor signals and / or to a disturbance of a sensor signal, in contrast to an internal excitation of the sensor. For example, thermal-mechanical stresses, temperature influences, moisture influences or vibrations generated outside the sensor element can generate an influence on a sensor element of the sensor, which on the one hand causes a signal disturbance and on the other hand is interpreted by the monitoring unit as a sensor defect.

In particular, environmental disturbances are often only temporary and can lead to the deactivation of important safety functions due to this unwanted error detection. A monitoring unit in the sensor often can not distinguish whether there is a real sensor defect or whether there is an environmental external influence of the sensor. First, it is important to establish the safe system state, i. to qualify a sensor signal as "invalid" in a fault condition. In addition, it should be classified within a short time, whether it is a significant and permanent sensor defect or whether a temporary external disturbance is responsible for the functional impairment.

While in the case of a sensor failure usually a replacement of the control unit with the sensor is required, which should be promptly made to ensure the proper use of a control system, in the event of a causal external influence, a control unit replacement is usually not required.

In order to allow a distinction between sensor defect and external influences, additional environmental status monitoring may be provided.

An additional consideration of the environmental status makes it possible on the one hand, if necessary, to avoid an unwanted long-term deactivation of control functions, especially since external influences are mostly of a temporary nature. On the other hand, taking into account the environmental status, an undesired error qualification with the attribute "defective control unit" due to external disturbances can be prevented.

The corresponding status information is referred to below as "environmental status". The environmental status may include status flag information about temperature, humidity, mechanical stresses, forces, linear accelerations, vibration accelerations, and frequency selective.

The environmental status can be recorded internally in the sensor, but also generated outside the sensor by means of further indicators or sensors.

(primäre Drive-Schwingung). Eine Drehbewegung s dieses Oszillators um eine zum Vektor $\overrightarrow{\nu }$

senkrechte Richtung generiert eine Corioliskraft ${\overrightarrow{\alpha }}_c$

senkrecht zur Fläche, die von den Vektoren $\overrightarrow{\nu }\text{ und }\overrightarrow{\omega }$

aufgespannt wird. Die Corioliskraft ${\overrightarrow{\alpha }}_c$

bewirkt die Anregung eines sekundären Schwingungsmodus des Oszillators mit Schwingungsrichtung senkrecht zur primären Drive-Schwingung (sekundäre Sense-Schwingung). Die Amplitude dieser sekundären Sense-Schwingung ist proportional zur wirkenden Drehgeschwindigkeit, so dass daraus das Drehratensignal generiert werden kann. Dieses Sensierungsprinzip basiert auf Resonanzstrukturen, die durch externe Beeinflussungen, welche Störschwingungen bewirken, beeinflusst werden können.A possible realization taking into account the environmental state will now be explained using the example of micromechanical rotation rate sensors. Micromechanical rotation rate sensors use the Coriolis effect to determine the rotation rate signal. This basic principle requires a permanently oscillating oscillator with a vibration velocity $\overrightarrow{\nu }$

(primary drive oscillation). A rotation s of this oscillator by one to the vector $\overrightarrow{\nu }$

vertical direction generates a Coriolis force ${\overrightarrow{\alpha }}_c$

perpendicular to the surface of the vectors $\overrightarrow{\nu }\text{and}\overrightarrow{\omega }$

is spanned. The Coriolis force ${\overrightarrow{\alpha }}_c$

causes the excitation of a secondary oscillation mode of the oscillator with oscillation direction perpendicular to the primary drive oscillation (secondary sense oscillation). The amplitude of this secondary sense oscillation is proportional to the effective rotational speed, so that the yaw rate signal can be generated therefrom. This sensing principle is based on resonance structures that can be influenced by external influences that cause spurious oscillations.

The stable permanent drive oscillation mode of the oscillator is ensured with control loops. This vibration mode is in turn permanently checked with one or more monitoring units to its plausible operating condition. The monitoring ensures the safe operation of the sensor and the plausibility of the sensor signals. An error in the control loop of the sensor oscillator can be detected, for example, by means of amplitude or phase monitoring, and a subsequent application such as a vehicle dynamics control can be quickly transferred to a safe state, for example deactivated.

The monitoring takes place in the area of the oscillator resonance frequency. Therefore, this monitoring mechanism is sensitive to mechanical disturbances in the range of the operating frequencies of the sensor oscillator.

It will now be explained how operating and monitoring modes of a yaw rate sensor can be modified so that a distinction can be made reliably between an "environmental fault" and a sensor fault.

The sensor error flags usually provided in the case of rotation rate sensors, which do not distinguish between sensor defect and environmental disturbance, are supplemented by an "environmental status", which can in particular improve the availability of a vehicle control system in harsh operating conditions with frequent external excitations of the rotation rate sensor. By means of this differentiation possibility it can be avoided that in certain situations a control unit is classified as defective and has to be exchanged, although the temporary restriction was "only" caused by a pronounced external influence. The additional environmental status improves the availability of a control system and avoids unjustified ECU replacement.

• - Temperatur;
• - Feuchtigkeit;
• - Luftdruck;
• - Vibration, insbesondere selektiv für verschiedene Frequenzbereiche;
• - Körperschall-Signale;
• - mechanische Verspannungen.

Below are some examples of relevant environmental status information that can be detected to evaluate a potential external impact on a sensor:

• - temperature;
• - Humidity;
• - air pressure;
• - vibration, in particular selective for different frequency ranges;
• - structure-borne noise signals;
• - mechanical tension.

The environmental status can be generated sensor-internally or sensor-externally and further processed by an analysis system, for example an evaluation circuit in the context of a signal conditioning. External can mean that environmental information of another sensor, for example, be used within the same ECU or (Electronic Control Unit), or information from other ECUs.

1 shows a block diagram of an embodiment of a sensor system with two ECUs 100-1 . 100-2 , each one or more sensors 102-1 . 102-2 . 102-3 and one signal conditioning circuit each 104-1 . 104-2 respectively. Every sensor 102-1 . 102-2 . 102-3 each has at least one sensor element 1020-1 . 1020-2 . 1020-3 and one environmental status detector each (UwDet) 1022-1 . 1022-2 . 1022-3 on. The sensor elements (Sig) 1020-1 . 1020-2 . 1020-3 each generate a sensor signal, and the environmental status detectors 1022-1, 1022-2 . 1022-3 detect external (such as those listed above) influences on the respective sensor elements 1020-1 . 1020-2 . 1020-3 and output, depending on the detection, an environmental status signal having one or more environmental status information such as "temperature> 40 ° C", "vibration at 100Hz", "structure-borne sound signal at 10kHz", etc. The signal conditioning circuits 104-1 . 104-2 one or more of the environmental status signals and possibly one or more of the sensor signals are supplied. For processing the supplied environmental status signals have the signal conditioning circuits 104-1 . 104-2 one environmental totals status generator each 1040-1 . 1040-2 which generates from the supplied environmental status signals an environmental status cumulative signal indicative of the environmental status of the sensors 102-1 . 102-2 or. 102-3 the corresponding ECU 100-1 . 100-2 represents. The signal conditioning circuit 104-1 also has a signal status generator 1042 on which the sensor signal of the sensor element 1020-1 and an output of the environmental sum status generator 1040-1 be supplied. Depending on the output of the environmental sum status generator 1040-1 can be the signal status generator 1042 at one by the output of the environmental sum status generator 1040-1 signaled external influence of the sensor 102-1 For example, set the signal status to "temporary fault" via its output signal. The output signals of the environmental sum status generators 1040-1 and 1040-2 and the signal status generator 1042 can via a bus system COM 106 be transmitted to other ECUs such as a vehicle dynamics control ECU or as in 1 shown by the ECU 100-2 to the ECU 100-1 ,

In addition to the use of environmental status information to improve the robustness, this can also be used selectively to improve the sensor signal precision. The above-mentioned environmental status information such as "temperature", "moisture", "mechanical stress", etc., for example, can lead to the fact that measured sensor signals are corrupted. Appropriate calibration of the sensor signals, depending on environmental status information, may improve the precision of the sensor signals provided.

Below is a basic operation of the environmental status detector using the example of an in 2 Based on a block diagram rotation rate sensor shown 10-4 described based on the Coriolis principle.

The drive oscillation of a drive oscillation element D a MEMS 12-4 the rotation rate sensor 10-4 is controlled stable by means of a DC drive control circuit and ensures the frequency-stable permanent oscillation of the drive oscillation element D of the MEMS 12-4 with the resonant frequency of the drive oscillation ω _D in the drive oscillation plane. A rate of rotation to be measured generates a resulting deflection in the sense vibration plane according to the Coriolis effect. This sense vibration plane has a resonance ω _S near the Driveschwingung ω _D , By means of a readout structure of a sense vibration element S of the MEMS 12-4 an analogue signal proportional to the measured rate of rotation is provided. In a signal processing path Sig, the sensor signal is generated, in particular by signal conversion (eg CV), optionally AD conversion, and signal conditioning, demodulation and signal filtering. A MON module monitors the various sub-modules or elements DC . D . S and Sig for a correct function. An additional environmental detector UwDet, the output signals of the sub-modules or elements DC . D . S and Sig are allowed to discriminate between a sensor defect and an environmental disturbance and can output a corresponding environmental status signal.

3 shows an embodiment of a rotation rate sensor 10-3 with a MEMS 12-3 , in addition to the drive and sense vibration elements D . S an integrated separate accelerometer cell Acc 14-3 has, which is designed so that they especially in the frequency range of the drive and sense frequency of the vibration elements D . S the rotation rate element 12-3 is sensitive. By suitable signal evaluation measures in the environmental detector UwDet resonance excitations of the sensor element 12-3 be identified and a resonance status signaled. In particular, such an identification in the environmental detector UwDet by means of band-pass filtering (filter bandpass) of the signals of the acceleration sensor cell Acc 14-3 be realized, for example by the filter bandpass from the supplied signals of the acceleration sensor cell Acc 14-3 a signal spectrum in the range of a resonant frequency, which corresponds to the drive and sensor frequency of the vibration elements D . S of the MEMS 12-3 is adjusted, filters out. The filtered-out signal spectrum can then be compared with a threshold value via a comparator Compare. Depending on the comparison, the evaluation of a signal fault can then be made. For example, when the threshold is exceeded, it can be concluded that in the of the Accelerometer cell Acc 14-3 generated signal is present, which suggests an external influence on the drive and sense frequency, so that a signal disturbance in the form of an external vibration influence with the environmental status signal can be signaled by the environmental detector UwDet.

The acceleration sensor cell Acc 14-3 can be monolithic in the module of the rotation rate element 12-3 be integrated as it is in 3 is indicated. However, a separate sensor chip with an acceleration sensor cell can be used for the resonance detection. By way of example, the sensor chip may be the acceleration sensor chip of a combined yaw rate / acceleration sensor.

4 shows an embodiment of a rotation rate sensor 10-3 with a MEMS 12-3 like the one in 2 shown yaw rate sensor 10-4 , In this rotation rate sensor 10-3 becomes an external separate acceleration sensor cell Acc 14-2 used within an additional sensor chip Sensor2 as a resonator for resonance detection, which is particularly sensitive in the frequency range of the drive and sense frequency of the rotation rate element. By suitable signal evaluation measures resonance excitations of the sensor element 12-4 identified and a resonance status signaled by the environmental detector UwDet. The acceleration sensor cell Acc 14-2 can be on the same circuit board, in the same controller as the sensor element 12-4 or integrated in another control device with sufficient mechanical coupling.

5 shows an embodiment in which a rotation rate sensor 12 with vibration elements D and S, in particular a rotation rate MEMS, at least one integrated, separate from the vibration elements D, S resonator Res 14 having. The design of this at least one resonator 14 is optimized to resonance frequencies, the resonance frequencies of the vibration elements D and S and possibly other sensitive frequencies of the rotation rate sensor 12 can correspond. In the case of a resonance disturbance of the rotation rate sensor 12 also becomes the integrated resonator 14 mechanically excited to vibrations, whereby an external influence of the sensor signal can be detected.

The transfer of the output signals of the resonator 14 to electrically detectable signals can by means of the already in the rotation rate sensor 12 used technologies such as capacitive (C / V), piezoelectric or piezoresistive detection take place. At the in 5 In the embodiment shown, the environmental detector UwDet 16 a signal converter 160 up, from the output signal of the resonator 14 , in particular a vibration, generates a voltage signal. Further, an amplifier 162 provided, which amplifies the voltage signal. In the simplest approach, the amplified, analog voltage signal in the evaluation circuit of the environmental detector UwDet 16 against thresholds by means of a comparison circuit or a comparator 166 be compared. Optionally, a comparison of digital signals after an additional analog-to-digital conversion by an analog-to-digital converter AD 164 occur. Regardless of the type of evaluation method selected, when a critical threshold value is exceeded, it may be indicated that a resonance disturbance of the rotation rate sensor has occurred 12 must be present, especially the evaluated signal of the resonator 14 can be excited with the same frequency to vibrate, with which also the vibration elements D and S the rotation rate sensor 12 swing. A calibration of the threshold values can be achieved by means of the resonance behavior of the vibration elements D and S be determined. The thresholds can be set so that any safety-critical signal disturbance due to a resonance excitation from the environmental detector UwDet 16 can be recognized.

In 6 the relationships between the fundamental functional principle of a micromechanical rotation rate sensor and the proposed detection mechanisms are shown.

Left in 6 are the two resonators of a rotation rate element 120 in the form of a MEMS cell 12 represented with the mutually perpendicular directions of the drive and the sense vibration with corresponding resonance frequencies. In the signal evaluation ASIC 18 This vibration state of the resonators is used as a feedback signal for the control of the drive oscillation, as well as a measure of the rotation rate to be measured in the case of the sense oscillation.

Right in 6 are the two additional resonant elements or resonators 140 and 142 shown using the same manufacturing processes monolithic in the MEMS cell 12 can be integrated, which also for the production of the structures of the rotation rate element 120 be used. The resonance element 140 has a resonator frequency f1 to the drive oscillation of the rotation rate element 120 is adjusted, and the resonant element 142 has a resonator frequency f2 to the sense vibration of the rotation rate element 120 is adjusted. In the case of resonance excitation of at least one of these structures of the rotation rate element 120 becomes at least one of the resonators 140 . 142 put into mechanical vibrations. These oscillations can be converted into electrically detectable signals by means of capacitive, piezoelectric or magnetic sensing so that they are in the signal evaluation in the ASIC 18 from the environmental detector 16 can be further processed and evaluated. It makes sense to use the methods already used for the sensor signal evaluation.

• - Toggeln von internen Zuständen;
• - Demodulation;
• - Delta-Frequenz-Analyse;
• - Spezifische Signaturen verschiedener Fehlerflags.

7 shows an embodiment of a rotation rate sensor 10 - 5 who is different from the one in 2 In the embodiment shown, it is different in that all monitoring functions are used in the module MON, but the monitoring mechanisms are modified in such a way that a distinction between a sensor defect and a resonance disturbance is possible. In the MON module, for example, the following functions can be implemented:

• - tokens of internal states;
• - demodulation;
• - Delta frequency analysis;
• - Specific signatures of different error flags.

These measures can by definition have a frequency-selective effect, since they can work on the mechanisms of action of the standard operating mode.

8th shows an embodiment of a rotation rate sensor 10-6 in which the resonator or resonance detector based on a second yaw rate sensor element 12-62 is realized. This differs from the first rotation rate element 12-61 especially in the resonance frequencies of the Driveschwingung D1 and the sensory oscillation S1 , A significant difference between the resonance frequencies of D and D1 or according to S and S1 causes an acting resonance disturbance to interfere only on a sensor element.

The useful functions of these redundant sensing systems initially require both signals in order to be able to sufficiently fulfill the safety requirements in all operating states.

In the case of a significant signal difference between both redundant signals - due to a sensor failure or due to an environmental disturbance - the safety function is deactivated and, if necessary, a control unit error is classified. By means of this monitoring, the erroneous signal can not be identified, so that it is not possible to continue the function for a limited time with a signal channel in the context of the security requirements. The use of an environmental status detector UwDet makes it possible to identify a temporary external fault, to assign this fault to a sensor channel, whereby the application can be temporarily continued with the undisturbed signal channel. Consequently, this characteristic can lead to an improvement in the availability of safety functions, especially in safety-critical situations.

9 shows a block diagram of another embodiment of a sensor system, which differs from the in 1 shown in the signal conditioning circuit 104-3 the ECU 100-1 different. The signal conditioning circuit 104-3 indicates next to the environmental totals status generator 1040-1 a signal status generator 1042-1 which receives the output of the environmental sum status generator 1040-1 is fed, and a signal calibrator SigKalib 105 on which the sensor signal of the sensor element 1020-1 and the output of the environmental sum status generator 1040-1 be supplied. The environmental status information in this embodiment serves to improve signal precision in the event that there is a correlation between sensor signal and environmental status. An additional signal calibration by means of the signal calibrator SigKalib 105 within the signal conditioning, taking into account the environmental status information, makes it possible to compensate for unwanted restriction of the signal precision.

By the environmental status detector included in the above embodiments, the following technical advantages can be obtained:

The availability of driving dynamics sensors can be improved.

In conventional sensors, the monitoring functions for detecting sensor-internal defects are optimized for the detection of sensor defects. These monitoring functions often respond to external environmental disturbances, although there is no real sensor defect. To ensure maximum safety with high system availability, therefore, very long qualification times for faults must be realized.

A clear distinction between real sensor defects and external disturbances by the environmental status detector makes it possible to react very quickly in the case of real sensor defects and thus to increase the safety of the system. In addition, by uniquely identifying external disturbances, it is possible to avoid qualifying an undesired "defective controller" state, thereby increasing the availability of the systems.

Finally, the precision of driving dynamics sensors can be improved.

The present invention can enable a distinction between real sensor errors of environmental errors caused by environmental conditions.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1249371 A1 [0003]
• DE 102006031730 A1 [0004]
• DE 102007037298 B1 [0005]
• DE 102007046982 B3 [0006]

Claims (10)

Sensor (10) with - A sensor element (12) which is designed to oscillate in an operating state of the sensor with at least one predetermined oscillation frequency, wherein from the vibrations, a sensor signal can be derived, and - At least one resonator (14) which is designed to oscillate at a corresponding external excitation of the sensor with at least one resonator frequency, which is adapted to one of the predetermined oscillation frequencies of the sensor element and / or to a further frequency of the sensor element. Sensor after Claim 1 , characterized in that detection means (16) are provided, which are designed to monitor the at least one resonator and to detect vibrations of the resonator in the region of the at least one resonator frequency. Sensor after Claim 2 , characterized in that the detection means (16) are adapted to generate at least one electrical signal for electronic processing by means of capacitive, piezoelectric and / or piezoresistive detection of the oscillations of the at least one resonator. Sensor after Claim 2 or 3 , characterized in that an evaluation circuit (160, 162, 164, 166) is provided, which is designed to process detected oscillations of the resonator in the region of the at least one resonator frequency and to generate an indicator signal dependent thereon. Sensor after Claim 4 characterized in that the evaluation circuit (160, 162, 164, 166) is adapted to derive a parameter from detected oscillations (160) and compare the derived parameter to at least one threshold (166) and generate the indicator signal when the derived one Parameter exceeds one or more thresholds. Sensor after Claim 5 , characterized in that the evaluation circuit (160, 162, 164, 166) is adapted to calibrate the at least one threshold based on a resonance behavior of the sensor element by the at least one threshold value is set such that an external excitation of the sensor, which is a vibration causes the sensor element in the range of at least one predetermined oscillation frequency, causing a threshold exceeded. Sensor according to one of the preceding claims, characterized in that the sensor element (120) is a micromechanical rotation rate sensor having a first predetermined oscillation frequency and a second predetermined oscillation frequency, wherein the first and the second predetermined oscillation frequency may be different. Sensor after Claim 7 , characterized in that it comprises an additional first and a second micromechanical resonator (140, 142), wherein the resonator frequency of the first micromechanical resonator is adapted to the first predetermined oscillation frequency and the resonator frequency of the second micromechanical resonator to the second predetermined oscillation frequency. Sensor system having at least one sensor (102-1, 102-2, 102-3) according to one of the preceding claims and a sensor signal processing (104-1, 104-2), which is designed, the sensor signal of the at least one sensor depending on a measurement signal to process at the at least one resonator frequency of the at least one resonator. Sensor system after Claim 9 characterized in that the sensor signal processing (104-1, 104-2) is designed to suspend processing of the sensor signal of the at least one sensor when the measurement signal at the at least one resonator frequency of the at least one resonator oscillates at the at least one predetermined oscillation frequency of the Sensor element signals.

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