JP2013064635A - Vibration sensor system and failure diagnosis method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration sensor system capable of easily diagnosing failure of a vibration sensor without being affected by noise due to vibration of the vibration sensor and other external devices, and a failure diagnosis method.SOLUTION: The vibration sensor system comprises a vibration sensor having a surface elastic wave resonator, and an interrogator having a failure determination processing unit for diagnosing failure of the vibration sensor. The vibration sensor system: transmits a carrier wave signal formed by chopping it into pulse state, from the interrogator to the vibration sensor; receives the reflected wave; causes an envelop detector circuit of the failure determination processing unit to detect an envelop waveform of the reflected wave; and detects presence/absence of the feature of a normal waveform appearing on a first envelop waveform that is a rising part of the envelop waveform and a second envelop waveform that is a falling part when the function of the surface elastic wave resonator of the vibration sensor normally functions, thereby determining the failure of the vibration sensor.

Description

  The present invention relates to a vibration sensor system and a failure diagnosis method for diagnosing a failure of a vibration sensor using surface acoustic waves.

  Conventionally, a method disclosed in Patent Document 1 is known as a method of diagnosing a failure of a vibration sensor using surface acoustic waves. In Patent Document 1, it is determined whether or not the vibration sensor is out of order by comparing a record of a state in which the vibration sensor is operating normally and a received signal of the vibration sensor when monitored.

JP 2008-175678 A

  Therefore, an object of the present invention is to provide a vibration sensor system and a failure diagnosis method that can easily diagnose a failure of the vibration sensor without being affected by vibration of the vibration sensor or noise caused by other external devices.

  In order to solve the above problems, a vibration sensor system according to the present invention includes a vibration sensor having a surface acoustic wave resonator and an interrogator having a failure determination processing unit for diagnosing a failure of the vibration sensor. In the vibration sensor system, the interrogator transmits a chopped carrier wave signal to the vibration sensor, the interrogator receives a reflected wave from the vibration sensor, and the failure determination processing unit The envelope waveform of the reflected wave is detected, and the presence or absence of a normal waveform characteristic that appears when the surface acoustic wave resonator of the vibration sensor is functioning normally is detected at the rising and falling portions of the envelope waveform. When there is no characteristic of the normal waveform, it is determined that the vibration sensor is faulty.

  Here, a normal vibration sensor is a state where the surface acoustic wave resonator functions normally, and a failure of the vibration sensor indicates a state where the function of the surface acoustic wave resonator is impaired.

  By transmitting a carrier wave chopped in a pulse shape to the vibration sensor, it is possible to confirm a rising portion and a falling portion that are not obtained in the case of a continuous wave in the envelope waveform of the reflected wave. A normal waveform that appears only when the surface acoustic wave resonator of the vibration sensor is functioning normally appears at the rising and falling parts. Sensor failure can be determined.

  In order to detect the envelope waveform of the reflected wave, the difference in the waveform of the reflected wave due to the noise of the vibration sensor or noise from other external devices will not affect the judgment of the vibration sensor failure. Since this phenomenon occurs due to surface acoustic wave resonance, it is possible to easily diagnose a failure of the vibration sensor without being affected by these noises.

  Further, the normal waveform according to the present invention may be characterized in that the rising portion of the envelope waveform has periodicity and that the falling time of the envelope waveform takes a predetermined time or more.

  When the envelope waveform of the reflected wave radiated from the vibration sensor is detected, it appears when the vibration sensor is broken down from the time immediately after the rising to a stable voltage due to the effect of surface acoustic wave resonance of the vibration sensor. A waveform with no periodicity is generated. Therefore, a failure of the vibration sensor can be determined by detecting that it has a specific frequency component for a predetermined time from the rising edge. Further, the failure of the vibration sensor can be determined by detecting that the falling portion is longer than the falling time required when the vibration sensor is broken. Furthermore, since the characteristics of the normal waveform appear even when the vibration sensor is subjected to vibration from the outside, it is possible to perform failure diagnosis without being influenced by the presence or absence of vibration of the vibration sensor.

  In addition, the vibration sensor of the vibration sensor system according to the present invention is electrically connected to the piezoelectric substrate, the surface acoustic wave resonator having the comb electrode formed on the piezoelectric substrate, and the comb electrode. The antenna part currently provided may be further provided.

  Here, the state in which the function of the surface acoustic wave resonator is impaired means that an abnormality has occurred in the comb electrode, and the failure of the vibration sensor means that the comb electrode is disconnected or between the comb electrode and the antenna. Abnormalities such as wire breakage, and abnormalities such as breakage of the piezoelectric substrate at the portion where the comb electrode is formed are shown.

  The interrogator of the vibration sensor system according to the present invention may further include an antenna unit that transmits the carrier wave signal to the vibration sensor and receives a reflected wave from the vibration sensor.

  The interrogator of the vibration sensor system according to the present invention includes a first transmission unit and a second transmission unit for generating output signals of different frequencies, and an output signal output from the first transmission unit. A first demultiplexer for demultiplexing the signal into two outputs, and one of the output signals output from the first demultiplexer is pulsed with the output signal output from the second transmitter The first mixer that performs chopping, the circulator that outputs the chopped output signal to the antenna unit, and the input signal that is input from the antenna unit to the second mixer, and the first demultiplexer that is output There may be provided the second mixer to which the other output signal and the input signal are inputted, and the second duplexer for outputting the signal outputted from the second mixer to the failure determination processing section. .

  A rising portion of a waveform that cannot be detected by a continuous wave by chopping the output signal output from the first transmission unit in a pulse shape with the output signal output from the second transmission unit and transmitting it as a carrier wave to the vibration sensor And you will be able to get the falling part. Furthermore, a normal waveform that does not appear when the function of the surface acoustic wave resonator of the vibration sensor is impaired is generated at the rising and falling portions of the envelope waveform of the reflected wave transmitted from the vibration sensor to the interrogator. Therefore, it is possible to determine the failure of the vibration sensor by determining the presence or absence of the characteristics of the normal waveform.

  The fault diagnosis method of the present invention includes a vibration sensor having a surface acoustic wave resonator and an interrogator having a function of diagnosing a fault of the vibration sensor, and chopping pulses from the interrogator to the vibration sensor. A process of transmitting the carrier wave signal, a process of detecting an envelope waveform of the reflected wave received by the interrogator from the vibration sensor, and a surface acoustic wave resonance of the vibration sensor at a rising portion and a falling portion of the envelope waveform Detecting whether there is a feature of a normal waveform that appears when a child function is functioning normally, and determining that the vibration sensor is faulty if there is no feature of the normal waveform It is characterized by that.

  Further, the normal waveform of the fault diagnosis method according to the present invention is characterized in that the rising portion of the envelope waveform has periodicity, and the falling time of the envelope waveform takes a predetermined time or more. And

  According to the present invention, the rising portion and the falling portion of the reflected wave that cannot be obtained with the continuous waveform can be confirmed by transmitting the pulse chopped carrier wave to the vibration sensor. In addition, a waveform at normal time that does not occur when the function of the surface acoustic wave resonator is impaired appears at the rising and falling portions. Sensor failure can be determined. In addition, the normal waveform is a phenomenon that occurs due to surface acoustic wave resonance of the vibration sensor, and because the presence or absence of this normal waveform characteristic is detected by the envelope waveform of the reflected wave, vibration sensor noise and other external devices The difference in the waveform of the reflected wave due to noise does not affect the failure determination of the vibration sensor.

  From the above, it is possible to obtain a vibration sensor system and a failure diagnosis method capable of easily diagnosing a failure of the vibration sensor without being affected by vibration of the vibration sensor or noise caused by other external devices.

1 is a system configuration diagram of a vibration sensor system according to an embodiment of the present invention. It is a perspective view which shows typically the structure of the vibration sensor by embodiment of this invention. It is a simple block diagram of the interrogator by embodiment of this invention. It is a reflected wave in the vibration sensor system by this invention. It is a signal processing flowchart of the failure determination process part of the interrogator by embodiment of this invention. It is an envelope waveform of the rising part of a reflected wave when the vibration sensor of the vibration sensor system according to the present invention is functioning normally. It is an envelope waveform of the rising part of a reflected wave when the vibration sensor of the vibration sensor system according to the present invention is out of order. It is an envelope waveform of the falling part of a reflected wave in case the vibration sensor of the vibration sensor system by this invention is functioning normally.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system configuration diagram of a vibration sensor system according to an embodiment of the present invention. As shown in FIG. 1, the vibration sensor system of the present invention comprises a vibration sensor 1 having a surface acoustic wave resonator and an interrogator 6 having a failure determination processing section (not shown). The interrogator 6 transmits the carrier wave 3 from the antenna 5 to the vibration sensor 1 attached to the object, and the vibration sensor 1 that has received the carrier wave 3 by the antenna 2 responds to the impedance change of the surface acoustic wave resonator. The reflected wave 4 is radiated from the antenna 2. While the interrogator 6 transmits the carrier wave 3, the interrogator 6 monitors the reflected wave 4 from the vibration sensor 1, and detects the envelope waveform of the received reflected wave 4 by the failure determination processing unit. Further, the failure determination processing unit determines whether or not there is a characteristic of a normal waveform generated when the function of the surface acoustic wave resonator of the vibration sensor 1 is functioning normally at the rising and falling portions of the envelope waveform. If it is detected and there is no feature of the normal waveform, it is determined that the function of the surface acoustic wave resonator of the vibration sensor 1 is impaired and that the vibration sensor is faulty.

  FIG. 2 is a perspective view schematically showing the structure of the vibration sensor according to the embodiment of the present invention. As an example of the vibration sensor according to the present invention, a structural diagram of a vibration sensor for detecting a mechanical vibration phenomenon of glass is shown. As shown in FIG. 2, the vibration sensor 11 includes a plate-like piezoelectric substrate 14, a single-port surface acoustic wave resonator having comb-shaped electrodes 13 formed on the piezoelectric substrate 14, and the piezoelectric substrate 14 in one piece. It comprises a support substrate 15 that is supported like a cantilever and an antenna 12 that is electrically connected to the comb electrode 13.

  In addition, the piezoelectric substrate 14 of the surface acoustic wave resonator is supported at one end of the piezoelectric substrate 14 by the support substrate 15 so as to be able to vibrate, and the comb electrode 13 is located near the base of the support portion. Therefore, the vibration of the piezoelectric substrate 14 can be efficiently concentrated near the comb electrode 13. The quality factor of the piezoelectric substrate can be adjusted to about 50 to 3,000 by a fixing method with a known support substrate.

  When vibration is applied to the piezoelectric substrate 14 from the outside of the vibration sensor, the piezoelectric substrate 14 is distorted, and the distance between the electrodes constituting the comb electrode 13 and the velocity of the elastic wave propagating through the piezoelectric substrate 14 change. As a result, the impedance of the surface acoustic wave resonator changes. Here, the resonance frequency of the piezoelectric substrate 14 supported by the support substrate 15 is designed to belong to a characteristic frequency band in the mechanical vibration of the object to be detected.

  FIG. 3 is a simplified block diagram of an interrogator according to an embodiment of the present invention. As shown in FIG. 3, a transmission frequency signal is generated from a transmission unit 21 that is a first transmission unit, which is configured by a known PLL (Phase Locked Loop) or the like, and a demultiplexer that is a first demultiplexer 22 divides the signal into two. One of the two demultiplexed signals is sent as a transmission signal to the mixer 23 as the first mixer, and the other is distributed as a local transmission signal to the mixer 30 as the second mixer via the attenuator 25. The transmission signal is chopped in a pulse shape by the transmission frequency signal output from the transmission unit 24 which is the second transmission unit in the mixer 23, and is transmitted from the antenna 28 via the power amplifier 26 and the circulator 27 with a desired electric energy. Sent. The carrier wave received by the vibration sensor is received from the antenna 28 as a weak reflected wave, and is amplified by the low noise amplifier 29 via the circulator 27. Then, after down-conversion by the mixer 30, it is sent to the duplexer 31 which is the second duplexer and split into two. One of the two separated signals is output as a detection signal having a vibration signal by the band pass filter 33, and the other is output to the failure determination processing unit 32. After detecting the envelope waveform of the reflected wave, the failure determination processing unit 32 checks the presence or absence of a normal waveform characteristic at the rising and falling portions of the envelope waveform. Determine failure.

  FIG. 4 is a reflected wave in the vibration sensor system according to the present invention. When the vibration sensor vibrates due to external vibration, a pulsed waveform with a frequency modulated by the external vibration applied to the vibration sensor by the pulsed chopped carrier wave is obtained, and when external vibration is not applied, it is chopped The carrier wave is obtained as a reflected wave as it is. An envelope waveform of the rising portion 41 that detects the envelope waveform of the reflected wave and confirms the presence or absence of the characteristics of the waveform at the normal time is defined as a first envelope waveform, and an envelope waveform of the falling portion 42 is defined as a second envelope waveform.

  FIG. 5 is a signal processing flowchart of the failure determination processing unit of the interrogator according to the embodiment of the present invention. As shown in FIG. 5, the reflected wave input to the failure determination processing unit is modulated into an envelope wave by the envelope detection circuit. Thereafter, it is confirmed whether or not the characteristic of the normal waveform that does not appear when the vibration sensor is broken appears in the first envelope waveform that is the rising portion of the obtained envelope waveform. Is obtained, it is determined that the vibration sensor is functioning normally. On the other hand, if the characteristics of the normal waveform are not obtained, check whether the characteristics of the normal waveform that do not appear when the vibration sensor is faulty appear in the second envelope waveform that is the falling portion. I do. If the characteristic of the normal waveform is obtained, it is determined that the vibration sensor is functioning normally. If the characteristic of the normal waveform is not obtained, it is determined that the vibration sensor is malfunctioning. Here, the characteristic of the normal waveform in the first envelope waveform is a waveform having a periodicity that is generated from immediately after rising until a stable voltage is obtained. Therefore, a failure of the vibration sensor can be determined by detecting that it has a specific frequency component for a predetermined time from the rising edge. The characteristic of the normal waveform in the second envelope waveform is a waveform that takes a falling time of a predetermined time or more. The failure of the vibration sensor can be determined by detecting that the falling time is longer than that required when the vibration sensor is broken.

  When the characteristics of the normal waveform cannot be obtained, in the vibration sensor of FIG. 2, the piezoelectric substrate in the portion where the comb electrode is disconnected, the wiring between the comb electrode and the antenna is disconnected, and the comb electrode is formed. It is determined that an abnormality such as breaking occurs in the vibration sensor, and the function of the surface acoustic wave resonator of the vibration sensor is impaired. If it is determined that the vibration sensor has failed, an alarm may be issued, or the user may be notified of the vibration sensor failure by warning means such as turning on a warning light. In addition, the number of times that the vibration sensor is determined to be malfunctioning depending on the presence or absence of the normal-time waveform feature can be arbitrarily set. For example, a failure may be determined when the characteristics of the normal waveform do not exist a plurality of times in succession. In this way, diagnosis redundancy can be increased.

  Examples of the present invention will be described below.

  An embodiment of the vibration sensor shown in FIG. 2 will be described. As the piezoelectric substrate 14, a quartz ST-cut substrate having a cantilever extending length of 2 mm, a width of 1 mm, and a thickness of 0.25 mm was used. At this time, the resonance frequency of the cantilever is 60 kHz. The interval between the comb electrodes was set to 0.35 μm so that the resonance frequency of the surface acoustic wave resonator was in the 2.45 GHz band. Further, the comb electrode is disposed in the vicinity of the support portion where the distortion of the piezoelectric substrate is maximized with respect to external vibration. In addition, the antenna is a 2.45 GHz band half-wave dipole antenna in accordance with the resonance frequency of the surface acoustic wave resonator. The quality factor of the piezoelectric substrate is about 100. The quality factor can be adjusted to about 50 to 3,000 by a known fixing method with a support substrate.

  In the vibration sensor according to the present embodiment, in FIG. 3, first, an output waveform having a frequency of 2.45 GHz is generated from the transmission unit 21, and one of the signals is sent to the mixer 23 as a transmission signal by the duplexer 22. Is distributed to the mixer 30 as a locally transmitted signal. The transmission signal is chopped in a pulse form at a frequency of 500 kHz output from the transmission unit 24 by the mixer 23, and transmitted from the antenna 28 via the power amplifier 26 and the circulator 27 with a desired electric energy. The carrier wave received by the vibration sensor is received from the antenna 28 as a weak reflected wave, and is amplified by the low noise amplifier 29 via the circulator 27. Thereafter, after down-conversion by the mixer 30, one of the branching filters 31 takes out an output signal having a vibration signal as a detection signal by the band-pass filter 33. The center frequency of this output signal is 60 kHz which is the resonance frequency of the cantilever. The other is output to the failure determination processing unit 32.

  As a reflected wave in the vibration sensor system according to the present embodiment shown in FIG. 4, a pulse waveform having a frequency of 2.45 GHz chopped at a frequency of 500 kHz was obtained.

  FIG. 6 is an envelope waveform of the rising portion of the reflected wave when the vibration sensor of the vibration sensor system according to the present invention is functioning normally. 4 is a first envelope waveform that is a rising portion of the envelope waveform obtained by modulating the reflected wave shown in FIG. 4 input to the failure determination processing unit into an envelope wave by the envelope detection circuit. As can be seen from FIG. 6, an envelope waveform having a period of 10 nanoseconds was generated in 40 nanoseconds immediately after the rise. This is due to the capacitive component of the surface acoustic wave resonance of the vibration sensor, and since the surface acoustic wave resonator functions normally, a waveform with periodicity is generated from immediately after rising until a stable voltage is obtained. doing.

  On the other hand, FIG. 7 is an envelope waveform of the rising portion of the reflected wave when the vibration sensor of the vibration sensor system according to the present invention is out of order. Abnormalities such as disconnection of the comb electrode of the vibration sensor, wiring between the comb electrode and the antenna, and breakage of the piezoelectric substrate where the comb electrode is formed have occurred in the vibration sensor. It is the 1st envelope waveform which is a case where the function of (2) is impaired and which is a rising portion of the envelope waveform. As can be seen from FIG. 7, the characteristics of the normal waveform appearing in the waveform of FIG. 6 when the vibration sensor is functioning normally are not generated. This is because the function of the surface acoustic wave resonator is impaired, and the carrier wave transmitted from the interrogator is returned as it is as a reflected wave without being resonated.

  FIG. 8 is an envelope waveform of the falling portion of the reflected wave when the vibration sensor of the vibration sensor system according to the present invention is functioning normally. The reflected wave shown in FIG. 4 input to the failure determination processing unit is modulated into an envelope wave by the envelope detection circuit, and is a second envelope waveform that is a falling portion of the obtained envelope waveform. As can be seen from FIG. 8, due to the effect of surface acoustic wave resonance of the vibration sensor, the fall time took 800 nanoseconds, and an envelope waveform longer than the fall time required when the vibration sensor failed was generated. On the other hand, when the function of the surface acoustic wave resonator is impaired, the carrier wave transmitted from the interrogator is returned as it is as a reflected wave without being resonated. Does not occur.

  As described above, the carrier wave chopped in a pulse shape is transmitted to the vibration sensor, the reflected wave is received by the interrogator, and the envelope waveform of the reflected wave is detected by the failure determination processing unit of the interrogator. Furthermore, by detecting the presence or absence of the characteristics of the normal waveform that appears when the surface acoustic wave resonator of the vibration sensor is functioning normally at the rising and falling portions of the envelope waveform, Thus, a vibration sensor system and a failure diagnosis method can be obtained that can easily determine a failure of the vibration sensor without being influenced by noise from the external device.

  As mentioned above, although the Example of this invention was described, this invention is not limited above, A structure change and correction and the change of a flowchart are possible in the range which does not deviate from the summary of this invention. For example, it was exemplified that a vibration sensor failure can be determined by detecting having a specific frequency component for a predetermined time from the rise, but not limited to this, from the waveform from the rise to the fall, A failure of the vibration sensor may be determined by detecting that it has a specific frequency component. That is, it is a matter of course that various modifications and corrections that can be made by those skilled in the art are also included in the present invention.

DESCRIPTION OF SYMBOLS 1, 11 Vibration sensor 2, 5, 12 Antenna 3 Carrier wave 4 Reflected wave 6 Interrogator 13 Comb electrode 14 Piezoelectric substrate 15 Support substrate 21, 24 Transmitter 22, 31 Splitter 23, 30 Mixer 25 Attenuator 26 Power amplifier 27 Circulator 28 Antenna 29 Low Noise Amplifier 32 Failure Determination Processing Unit 33 Band Pass Filter 41 Rising Part 42 Falling Part

Claims (7)

  A vibration sensor system including a vibration sensor having a surface acoustic wave resonator and an interrogator having a failure determination processing unit for diagnosing a failure of the vibration sensor, wherein the vibration sensor is pulsed from the interrogator to the vibration sensor. The interrogator receives a reflected wave from the vibration sensor, detects an envelope waveform of the reflected wave in the failure determination processing unit, and stands at a rising portion of the envelope waveform. In the lower part, the presence or absence of the characteristic of the normal waveform that appears when the surface acoustic wave resonator of the vibration sensor is functioning normally is detected. If there is no characteristic of the normal waveform, the vibration sensor fails. A vibration sensor system characterized by determining that the   2. The vibration according to claim 1, wherein the normal waveform has a periodicity at a rising portion of the envelope waveform, and a fall time of the envelope waveform takes a predetermined time or more. Sensor system.   The vibration sensor further includes a piezoelectric substrate, the surface acoustic wave resonator having a comb-shaped electrode formed on the piezoelectric substrate, and an antenna unit electrically connected to the comb-shaped electrode. The vibration sensor system according to claim 1 or 2.   The vibration sensor system according to claim 1, wherein the interrogator further includes an antenna unit that transmits the carrier wave signal to the vibration sensor and receives a reflected wave from the vibration sensor. .   The interrogator demultiplexes the first transmission unit and the second transmission unit for generating output signals of different frequencies and the output signal output from the first transmission unit into two outputs. The first demultiplexer, the first mixer for chopping one of the output signals output from the first demultiplexer with the output signal output from the second transmitter, and chopping A circulator for outputting the output signal to the antenna unit and outputting the input signal input from the antenna unit to the second mixer; another output signal output from the first duplexer; and the input signal 5. The apparatus according to claim 1, further comprising: a second duplexer that outputs the signal output from the second mixer to the failure determination processing unit. The vibration sensor system described in .   A vibration sensor including a surface acoustic wave resonator, and an interrogator having a function of diagnosing a failure of the vibration sensor, and transmitting a carrier wave signal chopped in a pulse form from the interrogator to the vibration sensor; The processing of detecting the envelope waveform of the reflected wave received by the interrogator from the vibration sensor, and the function of the surface acoustic wave resonator of the vibration sensor functioning normally at the rising and falling portions of the envelope waveform A failure diagnosis method comprising: detecting presence or absence of characteristics of a normal-time waveform that appears when the normal-time waveform is present; and determining that the vibration sensor is defective if the normal-time waveform characteristic is not present.   7. The failure according to claim 6, wherein the normal waveform is characterized in that a rising portion of the envelope waveform has periodicity, and a fall time of the envelope waveform takes a predetermined time or more. Diagnosis method.

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