JP2007241583A - Mechanical quantity measuring apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption simultaneously while realizing low-noise and highly accurate measurement, to reduce a battery exchange service life and to perform drive by the power source of a fine capacity in a wireless distortion sensor capable of measuring vibrations and dynamic distortions. <P>SOLUTION: In the mechanical quantity measuring apparatus, when measuring the dynamic distortion in a wireless distortion sensor module 13, output from a distortion sensor 2 is filtered by a filter 4 and is rectified and smoothed in a rectifying and smoothing circuit, then data processing is performed in a CPU and wireless communication is performed. Thus, since the sampling cycle of a data processing CPU is prolonged and a data amount to be wirelessly communicated is reduced, the power consumption of the CPU and the wireless communication is reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a system for measuring mechanical quantities by transmitting information obtained by a sensor.

  Conventionally, dynamic strain has been measured for life evaluation and abnormality diagnosis of structures. For structures such as bridge girders, it is also necessary to perform measurement in a place where the measurer cannot easily approach, so a sensor module consisting of a strain sensor and transmitter is attached to the object to be measured, and the receiver is located near the measurer. It is often measured wirelessly with an analysis device. Moreover, it is also attached to a device that moves by being driven by a motor or an engine, and abnormality monitoring is performed from a remote location.

JP 2005-114443 A

  In these cases, there is no appropriate power line near the object to be measured, and the strain sensor and the transmitter are often driven by a battery. When measuring the dynamic strain, it is necessary to continuously operate a control unit such as a CPU in the sensor module and a communication unit, and there is a problem that the battery is consumed heavily. For example, in order to measure a slow strain change, battery consumption can be prevented by intermittently operating a measurement control device, a communication unit, or the like. However, when measuring relatively fast periodic strain changes or irregular phenomena, it is necessary to always operate the measurement control device, communication unit, etc. so as not to miss the peak value of the strain. As a result, the battery is exhausted. Therefore, there is a problem that the battery needs to be replaced frequently. Similarly, since the power consumption of the sensor module is large in the past, it was impossible to drive with a minute capacity power source such as a solar cell.

  Therefore, even when dynamic strain is measured wirelessly, a system that operates with low power consumption and has a low frequency of battery replacement is desired.

  Therefore, the present invention provides a dynamic strain measurement system capable of suppressing any of the above problems. Provided is a dynamic strain measurement system that can be driven by a small-capacity power source such as a solar cell, with low power consumption and low battery replacement frequency to acquire periodic and relatively fast strain amplitude such as vibration. .

  In order to solve the above problems, a bandpass or high-pass filter for filtering the output from the strain sensor is provided in the sensor module, and a circuit for rectifying and smoothing the output from the filter is provided. Send the value to the transmitter. As a result, out of the periodic dynamic strain obtained by the strain sensor, only a specific frequency band or a band above a specific frequency is extracted, and this is rectified and smoothed to obtain the magnitude of the amplitude of that frequency band. Can only be taken out. When measuring periodic dynamic strain in a certain frequency band, a constant DC voltage proportional to the amplitude of the dynamic strain can be obtained, so even if the sensor module performs intermittent sensing or communication, the accuracy is high. High measurement is possible. Therefore, since intermittent communication is possible, the replacement frequency of the battery can be extremely shortened, and driving with a minute capacity power source such as a solar cell can be performed. In the following, a strain sensor, which is a typical example of a mechanical quantity sensor, will be mainly described.

  According to the present invention, the measurement data transmitted by the transmission / reception unit can be reduced, and the consumption of the transmission / reception unit having a particularly large power consumption can be reduced. In addition, power consumption of a CPU or the like used for measurement can be reduced. As a result, the battery consumption can be reduced, the number of times of battery charging and replacement can be reduced, or the battery can be miniaturized and the mechanical quantity measuring device having the sensor chip can be miniaturized.

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

FIG. 1 shows a dynamic strain measurement system according to the present invention. In this embodiment, the measurement system is attached to a structure or device having a substantially periodic strain fluctuation. As shown in FIG. 1, the system includes a battery 1, a strain sensor 2, an amplifier 3, a filter 4, a rectification / smoothing unit 5, an A / D conversion unit 6, a data processing unit 7, The transmission / reception unit 8, the transmission / reception unit 9 provided in the receiver 14, and the abnormality diagnosis unit 10 are configured. The configuration of this system may be slightly changed depending on its measurement specifications, etc. Even in this case, the strain sensor 2, filter 4, rectification / smoothing unit 5, data processing unit 7, and transmission / reception unit 8 is necessary. The strain sensor 2 may be a strain gauge conventionally known as a strain gauge, in which a thin thin wire is formed on a film, or a piezoelectric element. However, as long as the strain sensor is formed on a silicon chip. Best in terms of noise resistance, sensitivity, and power consumption reduction. The filter 4 is preferably a band pass filter, but may be a high pass filter that cuts only low frequency components depending on the application. Some of the elements constituting the filter 4 may be attached as external components outside the silicon chip.

  The strain of the object to be measured is sensed as an electrical signal by the strain sensor 2 provided on the surface or inside of the specific measurement object. The sensing data is amplified by the amplifier 3 and then only a signal in a specific frequency region is extracted by the filter 4. Further, the rectifying / smoothing unit 5 obtains a constant DC voltage proportional to the amplitude of the dynamic strain. This value is digitized by the A / D conversion unit 6, and this digital value is intermittently transmitted by the data processing unit 7 and the transmission / reception unit 8. The A / D conversion unit 6 and the data processing unit 7 may use a commercially available one-chip CPU. In this case, there is an advantage that power consumption can be further reduced.

Here, for comparison with the present invention, details of the conventional system will be described with reference to FIG. Conventionally, the output from the strain sensor 2 is input to the A / D converter 6 through the amplifier 3,
The data processing unit 7 such as a CPU and the transmission / reception unit 8 operate almost continuously. That is, when relatively high frequency dynamic strain is measured, highly accurate measurement is impossible unless the data processing unit 7 such as a CPU is operated almost always to measure the entire fine waveform. For example, as shown in FIG. 3, when the periodic high-frequency distortion amplitude is to be measured, if intermittent sensing is performed, the peak position may not be detected, so the distortion amplitude can be accurately obtained. Absent. Therefore, it is necessary to perform sensing so as to accurately trace the change in strain. For this purpose, the strain sensor 2 and the A / D conversion unit 6 such as the CPU and the data processing unit 7 are almost always moved to acquire the strain waveform in detail. It is essential to do. As described above, since the A / D conversion unit 6 such as the CPU, the data processing unit 7 and the strain sensor 2 are constantly operated, the battery is consumed quickly, and the battery must be replaced early. Further, since the constantly sensed data has a limit even if it is stored or processed in the sensor module 13, it is frequently transmitted to the outside, and the FFT (Fast Fourier Transform) analysis unit 11 performs frequency analysis in the receiver 14. There is a need. In this way, frequent communication has led to further battery consumption and forced replacement of the battery at an early stage.

  Therefore, it has been difficult for conventional systems to achieve both high-precision measurement and sensing with low power consumption.

  On the other hand, in the present embodiment, the filter 4 and the rectifying / smoothing unit 5 can convert the signal into a DC signal proportional to the distortion amplitude, so that the A / D conversion unit 6 such as the CPU or the data processing unit 7 is only for a short time. The value of the strain amplitude can be obtained as a DC value simply by moving. Therefore, the measurement accuracy of the distortion amplitude is hardly affected by the sampling period of the A / D conversion unit 6 such as a CPU, and it is possible to obtain the distortion amplitude information with high accuracy even when intermittent sensing is performed. . That is, instead of sensing every momentary change of the strain value and transmitting the enormous amount of data as in the prior art, in this embodiment, only the value of the strain amplitude is stored in the A / D converter 6 such as the CPU or the data. Since the processing unit 7 can handle the data intermittently and record it in a storage means (not shown) such as a RAM, and the data stored in the storage means can be intermittently communicated by the transmission / reception unit 8, the energy required for data processing and communication is also reduced. There is an advantage that less. That is, since the amount of information handled by the CPU and the communication unit is very small compared to the conventional case, the power consumption of the sensor module can be extremely reduced as a result, and the battery life can be extended. Furthermore, since filtering processing and rectification / smoothing processing are performed immediately after the strain sensor 2, an advantage of being resistant to noise also occurs. Furthermore, in this embodiment, since it is not necessary to perform FFT analysis on the receiving side, there is an advantage that the receiver 14 can be made compact.

  In this embodiment, transmission / reception is performed wirelessly, but even if transmission / reception is performed by wire, there is an advantage that it is resistant to noise. Moreover, as a power supply means such as a battery, there is a battery, a rechargeable battery, a capacitor, a capacitor, or the like that stores electric power inside, and a power generation means that generates power by sunlight or vibration may be provided. In any case, there is an effect of extending the life of the power supply means and reducing the size by reducing power consumption.

  FIG. 4 shows an implementation of this system. A strain sensor 2 is provided in the vicinity of the surface of the object 20 to be measured by any method of adhesion, bonding, or embedding, and in the vicinity thereof, an amplifier 3, a filter 4, a rectifying / smoothing unit 5, and an A / D conversion unit 6 are provided. , Data processing unit 7, transmission / reception unit 8, and battery 1, which are covered by a container 21. Such a mounting method is desirable when the strain generated in the DUT 20 is large. According to the present embodiment, since the current consumption of the sensor module 13 can be reduced, the battery 1 can be also small, and there is an advantage that it can be installed without taking up space as a whole. The place where the strain change is greatest is often a stress concentration place such as a corner, and the system can be made compact, so that it can be installed in a narrow place such as a corner.

  Further, FIG. 5 shows a system implementation suitable for measuring minute vibrations. In the present embodiment, in order to measure the vibration of the object to be measured 20, the attachment portion 24 is provided by any one of adhesion, bonding, and embedding in contact with the object to be measured 20, and the spring-like substance. The vibration is transmitted to 23. The spring-like substance is, for example, a helical spring, a leaf spring, an elastic substance, or the like, and is an object having lower spring rigidity than the object to be measured 20 or the semiconductor chip 15. Since the spring-like material 23 is connected to the heavy material 22 having a density higher than that of the spring-like material 23, the inertial force of the heavy material 22 acts, so that the vibration is converted into a large strain. A strain sensor 2 is provided in the vicinity of the surface of the spring-like material 23 by any one of adhesion, bonding, or embedding methods, and vibrations are detected by detecting changes in the strain of the spring-like material 23. According to the present embodiment, since the minute vibration is converted into a large vibration and detected by the strain sensor 2 and the current consumption of the sensor module 13 can be reduced, the battery 1 is also small, and the whole space is saved. The advantage is that it can be installed.

  Considering a device equipped with a motor or engine as the object to be measured 20, the cutoff frequency or center frequency of the filter 4 is determined so that the vibration frequency inherent to the motor or engine can be sensed. There is an advantage that anomaly detection becomes possible. In other words, when the motor or engine is abnormal, the vibration frequency generated changes, so the value of the strain amplitude measured in this system changes. Therefore, it is possible to detect the abnormality by receiving the sensing data of this system. It becomes possible. Conventionally, a complicated process of analyzing the signal from an accelerometer or strain sensor by wireless transmission and then analyzing it by FFT analysis or the like was necessary. The advantage is that the system can be realized.

  4 and 5 show the case where the circuit elements 2 to 8 are mounted so as to be stacked, the circuit elements may be mounted on one board or connected to each other.

<Multiple filters>
FIG. 6 shows an embodiment in which a plurality of filters 4a and 4b are provided. In this embodiment, a plurality of filters 4a and 4b having different filter cutoff frequencies and center frequencies are provided, and the output of the filter 4a is rectified and smoothed by the rectifying / smoothing means 5a, and the output of the filter 4b is rectified and smoothed. The rectifying means 5b rectifies and smoothes. According to the present embodiment, distortion data in a specific frequency band is extracted from sensing data in which various frequency distortion fluctuations are mixed, and the distortion amplitude obtained when the distortion amplitude is obtained with a DC signal and the frequency is changed. Value can be sent. That is, since the amount of information handled by the CPU and the communication unit of the first embodiment is very small, the power consumption of the sensor module can be extremely reduced as a result, and the battery life can be extended. This embodiment has an advantage that more complex and highly accurate measurement can be performed by measuring strain amplitudes in a plurality of frequency ranges.

  As shown in FIG. 7, the cutoff frequency and the center frequency of the filter 4 may be switched by a switch, and vibrations in a plurality of frequency ranges may be extracted by the single filter 4. Specifically, the value of a resistor (not shown) or the capacitance of a capacitor (not shown) constituting the filter 4 may be switched by the switch 12. In this case, since only one filter 4 is required, the advantage that the power consumption can be reduced, the advantage that the device can be reduced in size, and when several frequencies to be measured such as the natural frequency are determined in advance are flexible. Only the frequency can be selected and measured, and there is an advantage that the energy consumption can be reduced as much as it is not necessary to measure up to another frequency region. In addition, since a large number of frequency bands can be measured with a single filter 4, detailed measurement can be performed.

  The frequency at which the filter 4 performs measurement may be switched in order according to a frequency band stored in advance in a ROM or RAM in the sensor module 13. In this case, after performing distortion measurement for a certain frequency band for a predetermined time, the frequency band is changed and distortion measurement for another frequency band is performed. Further, the frequency range of the filter 4 may be changed by operating the receiver 14 and transmitting a command from the receiver 14 to the sensor module 13.

  FIG. 8 shows an embodiment in which a strain sensor 2, an amplifier 3, a filter 4 and a rectifying / smoothing unit 5 are formed on a semiconductor chip 15. The change in strain is measured by the strain sensor 2, amplified by the amplifier 3, the value is filtered by the filter 4, converted into direct current by the rectifying / smoothing unit 5, and then output to the pad 16. The filter 4 may be a band pass filter or a high pass filter. Further, an amplifier (not shown) may be provided after the filter 4, or an amplifier may be provided after the rectifying / smoothing lower part 5. It is desirable that the amplifier is provided at a necessary position according to the system application and the input distortion signal level.

  When the filter 4 is a band-pass filter, only a signal in the frequency band can be taken out, which is very effective when the frequency to be measured such as the natural frequency is clear. Abnormality can be detected by increasing or decreasing the strain amplitude of the frequency to be measured. In addition, in the case of a high-pass filter, a clear frequency is not determined, but it is suitable for motors and engines that are known to increase high-frequency vibration in the event of an abnormality. It is suitable for grasping.

  As the strain sensor 2 in the present embodiment, a strain sensor in which an impurity diffusion layer is locally provided on the surface of the semiconductor substrate is used. As a result, an element such as a transistor or a diode and the strain sensor can be mixedly mounted on a semiconductor substrate and can be produced by substantially the same manufacturing process, so that both high sensitivity, low power consumption and noise resistance can be achieved. That is, when a minute high-frequency distortion is to be detected, a high-sensitivity strain sensor 2 detects a minute strain change and amplifies the signal to minimize noise using the amplifier 3 on the same semiconductor substrate. Only the signal in the target frequency band can be selected by the filter 4 on the same semiconductor substrate. When the strain sensor 2 and the amplifier 3 are separate chips, noise easily enters here, and even if the filter 4 is used for filtering, the noise may be picked up. In addition, in either case where the amplifier 3 and the filter 4 are separate chips, or where the filter 4 and the rectifying / smoothing unit 5 are separate chips, the magnification of the amplifier 3 in the previous stage can be increased. Because it is not, noise is likely to be mixed in and high-precision measurement cannot be realized. That is, even when measuring a small strain change only by configuring the circuit from the strain sensor 2, the amplifier 3, the filter 4, and the rectifying / smoothing unit 5 on one semiconductor substrate as the semiconductor chip 15. A system that has sufficient noise resistance and can measure dynamic strain with high accuracy can be obtained.

  By using this chip, there are various advantages compared to the case where various electronic parts are mixedly mounted on the board and soldered. In this embodiment, since various electronic circuits and a minute strain sensor are formed on a semiconductor chip 15 formed of a semiconductor substrate, there is an advantage that external noise is less mixed and noise resistance is excellent. Therefore, even a minute strain signal can be measured with high accuracy, and dynamic strain measurement and abnormality diagnosis can be performed with high accuracy. Further, since each element forming the circuit operates with low power consumption, there is an advantage that the power consumption of the sensor module 13 can be reduced as a whole, and further, battery consumption can be suppressed. Furthermore, since the size can be reduced by using one chip, there is an advantage that it can be applied to strain measurement of a minute portion such as a stress concentration field.

  Note that when a filter having a cut-off frequency in a relatively low frequency region is used, a capacitor or a resistor externally attached to the semiconductor chip 15 may be required, but there are advantages similar to the above even on the spot.

  FIG. 9 shows an example in which a plurality of channels of filters 4 are provided on the semiconductor chip 15. In this case, the cutoff frequency and the center frequency of the filter 4 are set to be different from each other, and each filtered output is output from a different pad 16. Advantages similar to those obtained when a plurality of filters according to the first embodiment of the present invention are provided. Furthermore, since all the circuits are formed on one chip in this embodiment, there is an advantage that an increase in power consumption can be suppressed even if a plurality of channels are provided. Furthermore, even if a plurality of channels are provided, there is an advantage that the apparatus does not increase in size. Also, by providing a large number of channels, it is possible to provide the same function as FFT analysis on the semiconductor chip 15. That is, it is possible to output vibration intensity and strain intensity for each frequency from the plurality of pads 16 on the semiconductor chip 15. By connecting this output to an A / D conversion unit 6, a data processing unit 7 and a transmission / reception unit 8 provided separately, vibration intensity and strain intensity for each channel can be transmitted. As a result, the amount of data information can be reduced compared to the case where an actual distortion waveform is transmitted at high speed as it is, and the energy required for communication can be reduced. Further, since it is not necessary to perform FFT processing on the receiving side, there is an advantage that the receiving side device may have a limited data processing function such as a portable terminal using a low-speed CPU.

  FIG. 10 shows a semiconductor chip 15 having a function of changing the cut-off frequency or the center frequency by using a switch, although the filter 4 is of one type. Specifically, the capacitor capacity and resistance associated with the filter 4 are switched by a switch or made variable so that an arbitrary frequency is selected and its strain intensity and vibration intensity are measured. This method has an advantage that the circuit is simpler than that of the embodiment shown in FIG. 8 and can be operated with lower power consumption.

  FIG. 11 shows an embodiment in which a strain sensor 2, an amplifier 3, a filter 4, a rectifying / smoothing unit 5, and a CPU 17 are formed on a semiconductor chip 15. In addition to the advantage of the embodiment shown in FIG. 8, there is a merit that the power consumption can be further reduced. That is, in the embodiment shown in FIG. 8, an amplifier is often required between the rectifying / smoothing unit 5 and the A / D conversion unit 6, but in the system shown in FIG. As a result, the number of amplifiers can be reduced, and power consumption can be reduced accordingly.

FIG. 12 shows an implementation of this system. A semiconductor chip 15 is provided in the vicinity of the surface of the object 20 to be measured by any method of adhesion, bonding, or embedding, and in the vicinity thereof, the semiconductor chip 15, the A / D conversion unit 6, the data processing unit 7, and the transmission / reception unit 8 The battery 21 is covered with a container 21. Although there are advantages similar to those described with reference to FIG. 4, the use of the semiconductor chip 15 has the advantage of being compact and having low power consumption. Further, FIG. 13 shows a mounting form suitable for measuring minute vibrations. This also has the same merit as that described with reference to FIG. 5. However, the use of the semiconductor chip 15 has the merit of being compact and having low power consumption.

  12 and 13 show the case where each circuit element is mounted so as to be stacked, but other than the semiconductor chip 15 may be mounted on one board, and if each element is connected. good. Since the semiconductor chip 15 is a place where strain is measured, it is desirable that the semiconductor chip 15 be arranged so as not to be restrained by other members.

  Below, the Example about the use which measures the dynamic strain with the moderate change rate of about 0.1 Hz to about 10 Hz, and performs lifetime evaluation from the measured value is shown. FIG. 14 shows the system configuration. Similar to the one shown in FIG. 4 or FIG. 5, the strain sensor 2 is provided in the vicinity of the surface of the object to be measured 20 by any method of adhesion, bonding, or embedding, and the amplifier 3, A / D conversion is provided in the vicinity thereof. Unit 6, strain frequency analysis unit 18, transmission / reception unit 8, and battery 1, and container 21 covers them. Usually, the strain of the device under test 20 is measured by the strain sensor 2, amplified by the amplifier 3, and further converted into digital data by the A / D converter 6. Then, the strain amplitudes observed within a certain period of time are classified according to their magnitudes and counted as a frequency distribution by the strain frequency analysis unit 18. The combination of the strain level and the frequency distribution is transmitted from the transmission / reception unit 8. The A / D conversion unit 6 and the strain frequency analysis unit 18 are preferably a single device as a CPU.

  A system for performing such life evaluation itself has a problem of reducing battery consumption, as described in, for example, Japanese Patent Application Laid-Open No. 2002-357487. That is, in order to measure such a medium-speed dynamic strain and obtain a frequency distribution, it is necessary to always operate the A / D conversion unit and the CPU. It was.

  Furthermore, the system is a system that measures strain with a medium change rate exclusively. However, there is an example in which an abnormality of a structure is found by a high-speed dynamic strain change that cannot be measured by the system. In other words, it has become necessary to measure both the strain change in the high frequency range and the case of moderate strain change.

  FIG. 15 shows an embodiment of the present invention that solves this problem. The output from the strain sensor 2 is amplified by an amplifier 3, one of which passes through a filter 4 and is connected to a rectification / smoothing unit 5. The output from the other amplifier 3 passes through the low pass filter 26 and is directly connected to the A / D converter 6. In some applications, the low-pass filter 26 is not necessary. The filter 4 is preferably a band pass filter or a high pass filter. According to this embodiment, the distortion change in the high frequency range can be taken out by the filter 4, converted to direct current by the rectifying / smoothing unit 5, A / D converted, and intermittently measured by the data processing unit 7. On the other hand, since the strain measurement for the strain change from the low speed to the medium speed range is relatively low, the measurement waveform is directly A / D converted without being converted into direct current by the rectifying / smoothing unit 5 and data is obtained. The processing unit 7 can perform data processing almost continuously. In other words, in the conventional method, when measuring both the strain change in the high frequency range and the strain change from low to medium speed, both must continuously move the CPU for sensing. In addition, it is difficult to measure simultaneously with one CPU. That is, one CPU continuously measures a medium-speed strain change and counts it while classifying it into strain amplitude levels, and the other CPU faithfully follows the waveform of high-speed dynamic strain. Therefore, it was necessary to continuously perform measurement operation. However, in this embodiment, since high-speed dynamic strain can be measured intermittently, it can be measured without two independent CPUs. Therefore, the battery consumption is reduced accordingly, and a small system can be realized. There is an advantage. Further, since only one sensor needs to be installed on the object to be measured, there is an advantage that workability and reliability are remarkably improved. In FIG. 15, only one strain sensor 2 is provided, but two sensors for high speed and low / medium speed may be provided.

  In order to evaluate the life of structures, wireless communication modules that measure low and medium speed dynamic strains and count frequency distributions require the A / D converter and CPU to be constantly running. There was a problem that consumption of 1 was severe.

  Usually, in order to reduce the power consumption of such a system, the intermittent operation of the module is generally performed. This is done by using a timer or counter built in the CPU to measure power by turning on the main circuit, sensor circuit, amplifier circuit, etc. of the CPU at regular intervals, and setting the counter or timer after the measurement is completed. The sleep operation is entered. However, since an inaccurate measurement result is unavoidable if there is a large strain fluctuation during the rest period, conventionally, intermittent operation has not been adopted in the life evaluation of structures.

  In the following, an embodiment of the present invention will be described in which a system for measuring dynamic strain and performing life evaluation reduces battery consumption by incorporating intermittent operation and enables high-precision measurement.

  As a result of dynamic strain measurement of large structures and buildings such as iron bridges and piers, we found that the percentage of time with low strain of several hundred με or less was the majority of the total measurement time. . It was also found that when a large strain was applied, a sign of an increase in strain was observed in advance on the order of seconds. In other words, in large structures such as piers, the increase in strain is seen in advance because vehicles and railway vehicles approach, and because the natural frequency of the pier itself is small, a sign of a large strain change is in advance on the order of seconds. I knew it would appear. Here, the large structure is, for example, a bridge (including iron bridges, concrete bridges, piers, etc.), a large structure (including gates, buildings, dams, tunnels, dikes, etc.).

  In the present invention, this knowledge is utilized, and when the strain is sufficiently small and maintained, monitoring is performed by performing an intermittent operation, and when it is detected that the strain starts to increase, a transition to a continuous operation is performed. So, we succeeded in achieving both low power consumption and high precision measurement. Details are shown below.

  FIG. 16 shows an operation flow of the sensor module 13 in the present embodiment. First, a measurement period (measurement time) for estimating the lifetime is input to the sensor module 13, and further, the sensing pause time in the intermittent operation mode and the change amount of the strain sensor measurement value for setting the CPU in the continuous operation mode. Is input to the sensor module. The sensor module intermittently senses when measurement is started, and enters a continuous operation mode when the amount of change in the sensing value exceeds a preset change value. After that, continuous sensing is performed to measure the strain waveform, and the peak value and strain amplitude are measured. Further, the value of the distortion amplitude is divided into several levels, and the number of times at that level is counted. The counting method is the same as that generally called the rainflow method or the stress level cross-count method. Furthermore, when the amount of change in the measured value falls below a preset change value during a certain period, the mode shifts to the intermittent operation mode. This operation is repeated until the measurement time ends. Then, after the measurement time is over, how many times the strain amplitude of that level has occurred for each strain level, that is, frequency data is transmitted wirelessly.

  At this time, the sensing pause time in the intermittent operation mode and how to set the change value of the strain sensor measurement value for setting the CPU to the continuous operation mode are important for accurate measurement. . In the present invention, the sensing pause time in the intermittent operation mode is set to a long value of 0.1 seconds or more to reduce power consumption. By increasing the sensing pause time, the time from when the strain increases to the transition to the continuous operation mode increases, but as described above, before a large strain change occurs as a sign in large structures and buildings This is because distortion increases on the order of seconds, so that even if a precursor distortion increase is detected at a time interval of 0.1 seconds or more and the mode is slowly shifted to the continuous operation mode, measurement can be performed without missing a large distortion. It is desirable to set the threshold value for shifting to the continuous operation mode to such a value as to detect a strain increase which is a precursor of this large strain. In addition, strains whose peak values are near the threshold may not be detected without shifting to the continuous operation mode. However, in strain detection, it is important to detect large strains that affect the life of structures, etc. Even if detection of a relatively small strain is missed, the influence on the evaluation of strain measurement data is small. In consideration of the fact that the strain rises on the order of seconds, the upper limit of the sensing pause time is desirably 10 seconds.

  Further, in this embodiment, the trigger for setting the continuous operation mode is the amount of change in the strain measurement value, but if this is the absolute value of the strain sensor, a large problem occurs in the strain sensor made of a semiconductor chip. When the ambient temperature changes, the strain sensor is a semiconductor chip such as silicon, so a large thermal stress is generated between the measured object and the apparent unstrained point shifts, and no strain is generated. This is because a large strain value remains on the strain measurement value. Therefore, when the absolute value of the strain sensor is used as a threshold value, a malfunction occurs in that the trigger is not applied or the operation is continued in the continuous mode. In this embodiment, since the change amount of the strain is used as a determination criterion, even when the unstrained point is shifted, a large strain amplitude can be correctly measured.

  Furthermore, in this embodiment, since the trigger for setting the continuous measurement mode is the amount of change in the strain measurement value, a small strain amplitude is generated during the intermittent operation so that the maximum value slightly exceeds the threshold value. Even if this cannot be detected, there is an advantage that the accuracy is not reduced because the small strain amplitude only acts for a short time and does not have a great influence on the life evaluation. In addition, since it reacts sensitively to sudden strain changes, large strains can be detected with high accuracy in the continuous operation mode. That is, according to the present embodiment, there is an advantage that it is possible to achieve both saving of battery by intermittent operation and maintenance of measurement accuracy.

  In addition, according to the present embodiment, intermittent operation is possible without degrading measurement accuracy, so that the battery can be prevented from being consumed, and the advantage that measurement can be performed without replacing the battery for a long time is born.

  In addition, even if this Example uses the distortion | strain sensor of Example 1 shown in FIG. 1, even if it uses the conventional distortion | strain sensor shown in FIG.

  In this embodiment, how to send frequency data after the end of the measurement time is performed as follows.

  The system according to the present invention has a function of wirelessly transmitting measurement data within a measurement period after measurement for a certain time. However, since power transmission itself is a very battery consuming action, this reduction in power consumption greatly affects battery life. Therefore, in this embodiment, the transmission time is shortened by reducing the data to be transmitted as much as possible, and the amount of power required for transmission is reduced. That is, as shown in FIG. 17, at the end of the measurement, the frequency data is stored in the memory in the sensor module, but the one having the largest strain level is searched for and the strain level equal to or lower than that is found. Send only the ones, and do not send the ones with higher strain level. According to the present embodiment, energy required for transmission can be saved, so that the number of battery replacements can be reduced.

It is a block diagram which shows the structure of the mechanical quantity measuring system which is one Example of this invention. It is a block diagram explaining the structure of the prior art example. It is a figure explaining the technical subject of a prior art. It is a schematic diagram which shows the example of mounting of the mechanical quantity measuring system of this invention. It is a schematic diagram which shows the example of mounting of the mechanical quantity measuring system of this invention. It is a block diagram which shows the structure of the mechanical quantity measuring system which is one Example of this invention. It is a block diagram which shows the structure of the mechanical quantity measuring system which is one Example of this invention. It is a block diagram which shows the circuit structure of the semiconductor chip which is one Example of this invention. It is a block diagram which shows the circuit structure of the semiconductor chip which is one Example of this invention. It is a block diagram which shows the circuit structure of the semiconductor chip which is one Example of this invention. It is a block diagram which shows the circuit structure of the semiconductor chip which is one Example of this invention. It is a schematic diagram which shows the example of mounting of the mechanical quantity measuring system of this invention. It is a schematic diagram which shows the example of mounting of the mechanical quantity measuring system of this invention. It is a block diagram explaining the structure of the prior art example. It is a block diagram which shows the structure of the mechanical quantity measuring system of this invention. It is a flowchart which shows operation | movement of the mechanical quantity measurement system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery, 2 ... Strain sensor, 3 ... Amplifier, 4 ... Filter, 5 ... Rectification / smoothing part, 6 ... A / D conversion part, 7 ... Data processing part, 8, 9 ... Transmission / reception part, 10 ... Abnormal diagnosis Part, 11 ...
FFT analysis unit, 12 ... switch, 13 ... sensor module, 14 ... receiver, 15 ... semiconductor chip, 16 ... pad, 17 ... CPU, 18 ... strain frequency analysis unit, 19 ... life evaluation unit,
DESCRIPTION OF SYMBOLS 20 ... To-be-measured object, 21 ... Container, 22 ... Heavy substance, 23 ... Spring-like substance, 24 ... Attachment part, 25 ... Vibration detection apparatus, 26 ... Low pass filter.

Claims (17)

In a mechanical quantity measuring device that is installed on the object to be measured, measures the mechanical quantity, and transmits the measurement result,
Mechanical quantity detection means for detecting a mechanical quantity and outputting a signal;
First filtering means for extracting a signal of a first specific frequency from the signal;
First rectification / smoothing means for rectifying / smoothing the extracted signal;
Data processing means for processing the rectified and smoothed signal;
A mechanical quantity measuring device comprising: a transmitting means for transmitting the data-processed signal. In claim 1,
The mechanical quantity measuring apparatus according to claim 1, wherein the transmission means performs wireless transmission. In claim 1,
Second filtering means for extracting a signal of a second specific frequency different from the signal extracted by the first filter means from the signal output by the mechanical quantity detection means;
A second rectification / smoothing means for rectifying / smoothing the extracted signal;
A mechanical quantity measuring apparatus comprising: a data processing unit that processes data of the signal rectified and smoothed by the first rectifying and smoothing unit and the signal rectified and smoothed by the second rectifying and smoothing unit . In claim 1,
An apparatus for measuring a mechanical quantity, comprising: power supply means for storing power or generating power and supplying power to the transmission means. In claim 1,
A mechanical quantity measuring apparatus comprising the mechanical quantity detecting means, filtering means, rectifying / smoothing means, and data processing means on a single semiconductor substrate. In claim 1,
The mechanical quantity measuring device characterized in that the specific frequency taken out by the filtering means is variable. In claim 1,
A mechanical quantity measuring apparatus, wherein the data processing means is operated intermittently. In claim 1,
The mechanical quantity detection means is formed on a semiconductor substrate,
A mechanical quantity measuring apparatus connected to the object to be measured through an object having a spring stiffness smaller than that of the semiconductor substrate. In claim 1,
The data processing means includes
The rectified and smoothed signal;
A mechanical quantity measuring apparatus which performs data processing on a signal output from the mechanical quantity detecting means and not rectified / smoothed by a rectifying / smoothing means. In claim 1,
Third filtering means for extracting a signal of a third specific frequency different from the signal extracted by the first filter means from the signal output by the mechanical quantity detection means;
A mechanical quantity measuring device comprising: data processing means for processing data of the signal extracted by the third filtering means. In claim 1,
The data processing means classifies according to the magnitude of the mechanical quantity, and counts the frequency for each magnitude of the mechanical quantity. In the mechanical quantity measurement method that installs on the object to be measured, measures the mechanical quantity, and transmits the measurement result,
Sensing mechanical quantities and outputting signals,
Extract a specific frequency from the signal,
Rectifying and smoothing the extracted signal,
Data processing is performed on the rectified and smoothed signal,
A mechanical quantity measuring method for transmitting the data-processed signal. In claim 11,
The mechanical quantity measuring method, wherein the transmission is wireless transmission. In the mechanical quantity measurement method that installs on the object to be measured, measures strain, and transmits the measurement result,
The first measurement mode,
Having a second measurement mode with a measurement frequency greater than the first measurement mode,
A mechanical quantity measuring method, wherein the measurement is performed in the second measurement mode when the change amount of the strain measurement value measured in the first measurement mode is larger than a predetermined value. In a mechanical quantity measurement method that measures strain of a large structure or building and transmits the measurement result,
A first measurement mode in which the measurement time interval is 0.1 second or more;
Having a second measurement mode with a higher measurement frequency than the first measurement mode,
A mechanical quantity measuring method, wherein the measurement is switched to the measurement in the second measurement mode according to the magnitude of the measurement value measured in the first measurement mode. In claim 15,
A mechanical quantity measuring apparatus that performs measurement in the second measurement mode when a change amount of a strain measurement value measured in the first measurement mode is larger than a predetermined value. In the mechanical quantity measurement method that installs on the object to be measured, measures strain, and transmits the measurement result,
Measure strain,
Count the frequency for each measured strain magnitude,
Among the measured strains, a mechanical quantity measurement method characterized by transmitting a frequency of a strain having a maximum magnitude and a frequency of a magnitude magnitude less than that, and not transmitting a frequency of strain greater than the maximum strain.

Images