JP3419232B2 - Wave number counting method and vibration measuring device using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wave number counting method, and more particularly to a wave number counting method used in digital signal processing in the measurement field. Further, the present invention relates to a vibration measuring device, and more particularly to a vibration measuring device which is a basis for structural analysis of an object and which measures the vibration of the object without contact.

The vibration measuring device is used not only for measuring noise and car body characteristics such as engine, body, door, window and muffler, but also for detecting abnormal vibration of processing equipment such as drills and cutting tools. It also includes various objects that require vibration analysis.

The wave number counting method can be used for a device for counting the wave number using a threshold value and a device for counting time. For example, it is used for the measurement of the time of flight of ultrasonic waves in the ultrasonic distance measurement, the wave number measurement of the optical interference distance meter, and the wavelength measurement counter used in the frequency measurement.

[0004]

2. Description of the Related Art Conventionally, vibration measurement of a vehicle body has been performed by an acceleration pickup installed on an object or a moire vibrometer using slit light. The vibration of the object measured by the vibration measuring device is used for vibration analysis of the object.
By analyzing the structure of the object based on the amplitude at the resonance frequency, the rigidity of the object to be measured (for example, the quality of welding) is determined.

Further, abnormal vibration of a processing machine such as a drill motor is detected by a change in driving current of the motor or AE.
(Acoustic Emission) was used to detect the impact sound, and the pickup sensor was installed via a mounting jig.

[0006]

However, since the accelerometer is of a contact type, the weight of the sensor and the connecting cable affects the vibration, which makes accurate measurement difficult. Furthermore, with a moire vibrometer, although the overall vibration tendency can be known, the displacement of the vibration of the object cannot be measured.

Further, in measuring the vibration of a processing machine such as a motor, it is difficult to retrofit by detecting the change in the driving current of the motor, and it is difficult to detect when the drill diameter is 3 mm or less.
For this reason, it is difficult to detect the lack of gears of the motor by comparison with the vibration analysis result of a normal object, and in particular, in the case of a small motor, it is not possible to make an abnormality determination by the vibration measurement device and the vibration analysis device. there were.

Further, the detection by the impact sound detects the impact sound from broken teeth, but it has the disadvantage that the device is expensive and is easily affected by ambient noise, making it difficult to detect the impact sound. Furthermore, the condition that the surface to be brought into contact with the pickup microphone is desired to be flat is severe.

Further, since the vibration characteristics change due to the weight of the sensor and the cable, and the abnormal vibration detection condition changes at the position where the sensor is attached, the structure of the object cannot be stably and favorably analyzed. Therefore, a non-contact type vibration measuring device is desired, but a non-contact type vibration measuring device for measuring even vibration displacement is not known.

Further, since the object of vibration measurement is wide from the body of the vehicle to the small motor, and it is desired to incorporate the quality inspection of welding and the quality inspection of the processing machine into the manufacturing process, the vibration measuring device can be installed compactly. What is easy and cheap is desired.

Therefore, the applicant has an optical detection means for observing the laser light reflected from the object to be measured and a signal processing means for analyzing the waveform signal output from the optical detection means and detecting the sawtooth wave. Calculating means for calculating the switching time of the vibration direction of the measuring object based on the wavelength difference of each sawtooth wave detected by the signal processing means, and the switching time information calculated by the calculating means A vibration measuring device provided with a data conversion means for converting the wavelength of each sawtooth wave into displacement data of the object has been developed and already applied (Japanese Patent Application No. 8-185576).

As shown in FIG. 10, the signal processing means detects the sawtooth wave d corresponding to the displacement amount b of the vibration surface a of the object to be measured. One sawtooth wave is generated when the vibrating surface is displaced by a distance (λ / 2) that is half the laser wavelength. Therefore, by counting the number of sawtooth waves, the displacement of the measurement object can be measured.

However, in the method of measuring the displacement of the object to be measured by counting the sawtooth wave, as shown in FIG. 11, the sawtooth wave is generated by temperature drift or electromagnetic induction of a photodiode or an amplifier for photoelectrically converting a laser. There is a case where the center voltage level of V fluctuates (the two-dot chain line portion indicated by the symbol n in FIG. 11). At this time, the position where the wave number is counted in the sawtooth waveform is not constant, so that the measured vibration displacement becomes inaccurate. Further, when the center voltage level of the sawtooth wave greatly exceeds the ground level, the sawtooth waveform does not cross the ground level and the wave number is not counted.

When the moving direction of the vibrating surface changes, the moving speed approaches zero and the waveform becomes elongated. As shown in FIG. 12, if noise is added while the waveform is extended, the number of waves is erroneously counted when the waveform crosses the ground (two-dot chain line portion indicated by symbol n in FIG. 12).

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wave number counting method capable of improving the inconvenience of the conventional example and, more particularly, capable of accurately measuring the wave number even if the input signal contains noise. To aim. Further, it is an object of the present invention to provide a vibration measuring device capable of accurately measuring the vibration of a measuring object in a non-contact manner even if the input signal contains noise.

[0016]

Therefore, in the invention according to claim 1, a measuring step for measuring the amount of change of an input signal input from a measuring object through various media, and the measuring step is performed. And a crossing number counting step of counting the number of crossings between the waveform and a predetermined reference value according to the reception time of the waveform. Moreover, after the measuring step and before the crossing counting step, an envelope detecting step of detecting the upper and lower envelopes of the input signal measured in the measuring step, and the upper and lower envelopes detected by the envelope detecting step. An intermediate line extraction step of extracting a substantially intermediate level of the envelope as an intermediate line based on the line, the intermediate line extracted by this intermediate line extraction step, and the input signal waveform measured in the measurement step An area calculation step of calculating the area formed for each wave on the upper or lower part, and counting the one wave of the area when the area calculated by this area calculation step is larger than a predetermined area It is provided with a waveform specifying step for specifying an effective waveform of a target. The intersection number counting step is configured to count when the intermediate line extracted in the intermediate line extraction step and the waveform identified in the waveform identification step intersect in the upward direction or the downward direction. This is intended to achieve the above-mentioned object.

In the waveform counting method according to the first aspect, after the envelope is extracted in the envelope extracting step, the intermediate line which is the intermediate level of the envelope is calculated. Further, in the area calculation step, the upper part (FIG. 4A) or the lower part (FIG. 4B) of the area formed by the intermediate line and the input waveform signal is calculated. Then, the waveform specifying step discards the waveform having the area smaller than the predetermined area, and specifies only the waveform having the area larger than the threshold value area as the effective waveform. Therefore, in the crossing number counting step, the influence of noise is removed and the number of waves is counted (counted up).

According to the second aspect of the present invention, the light detecting means for observing the laser light reflected from the object to be measured and the waveform signal output from the light detecting means are analyzed and a predetermined effective sawtooth wave is detected. Signal processing means and displacement data generating means for generating displacement data of the measurement object according to the wavelength of each sawtooth wave detected by the signal processing means. Moreover, the signal processing means detects the upper and lower envelopes of the sawtooth wave, and the intermediate level of the envelope based on the upper and lower envelopes detected by the envelope detector. An intermediate line extraction unit that extracts the line, an area calculation unit that calculates the upper or lower area formed by the intermediate line and the sawtooth wave extracted by the intermediate line extraction unit for each wave, When the area calculated by the area calculation unit is larger than a predetermined area, a sawtooth wave specifying unit that specifies a wave having the area as an effective sawtooth wave is provided.

In the vibration measuring device according to the present invention, the sawtooth wave specifying unit discards the sawtooth wave whose area calculated by the area calculating unit is equal to or smaller than the predetermined area, and is equal to or larger than the predetermined constant area. The sawtooth wave of is specified as the counting target.
Further, the displacement data generation means obtains the displacement of the measurement object based on the wavelength of the sawtooth wave specified by the sawtooth wave specifying unit.

[0020]

DETAILED DESCRIPTION OF THE INVENTION

[First Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing the configuration of the wave number counting method according to the present invention. The wave number counting method includes a measuring step S1 for measuring a change amount of an input signal input from a measurement target through various media, and an envelope detection for detecting upper and lower envelopes of the input signal measured in the measuring step S1. The process includes a step S2 and an intermediate line extraction step S3 for extracting a substantially intermediate level of the envelope as an intermediate line based on the upper and lower envelopes detected by the envelope detection step S2.

Further, the area formed for each wave above or below the intermediate line by the intermediate line extracted in the intermediate line extracting step S3 and the input signal waveform measured in the measuring step S1 is determined for each wave. An area calculating step for calculating and S4, and a waveform specifying step S5 for specifying one wave of the area as an effective waveform to be counted when the area calculated by the area calculating step S4 is larger than a predetermined area ing.

Then, the number of crossing counting step S6 for counting the number of crossings between the waveform specified in the waveform specifying step S5 and a predetermined reference value according to the reception time of the waveform.
Is equipped with. The intersection number counting step S6 is performed by the intermediate line and waveform identifying step S5 extracted by the intermediate line extracting step S3.
It counts up when the waveform specified in step 4 intersects in the upward or downward direction.

FIG. 2 is an explanatory diagram showing an example of a waveform which is the object of wave number counting. The operation of each step shown in FIG. 1 will be described with reference to FIG. In the measurement step S1, the measurement amount input through various media such as radio waves, light waves, and sound waves from the measurement target is converted into an electric signal and output. As shown in FIG.
In this embodiment, a signal in which this electric signal (input signal k) becomes a sawtooth wave is an object of counting. In the present embodiment, the input signal k measured S1 in the measurement process is amplified and converted into digital data.

Then, in the envelope extraction step S2, the envelope h of the input signal k is extracted. This envelope h is generated by the upper part and the lower part of the input signal k. Further, in the intermediate line extracting step S3, the value of the substantially intermediate level of the envelope h is calculated at regular time intervals, and this is set as the intermediate line c. Further, in the area calculation step S4, the area of the hatched portion shown in FIG. 2 is calculated in order to calculate the upper area here.

Further, in the waveform specifying step S5, it is determined whether or not the area of each wave is equal to or more than a predetermined constant area, and the waveform having the predetermined area or more is set as the waveform to be counted. Then, regarding the two-dot chain line portion indicated by the symbol n in FIG. 2, the thin waveform on the right side is not treated as a waveform because the area is less than a certain value. At this time, in the waveform specifying step S5, the wavelength of the discarded waveform portion is divided into two and added to the wavelength of one wave before and after that.

After the influence of the noise portion is removed in this way, the crossing counting step S6 is carried out in the waveform specifying step S5.
The number of intersections of the wave identified in step 1 and the intermediate line c is counted. As described above, according to the first embodiment, the number of waves can be effectively counted by the digital signal processing even for a waveform including a noise component and having a voltage level fluctuation as shown in FIG. The accuracy of various measurements and image processing can be greatly increased.

[Second Embodiment] FIG. 3 is a block diagram showing the configuration of a vibration measuring apparatus according to the present embodiment. As shown in FIG. 3, the vibration measuring device includes a light detecting means 10 for observing laser light reflected from an object to be measured, and the light detecting means 1.
Signal processing means 20 for analyzing the waveform signal output from 0 and detecting a predetermined effective sawtooth wave, and a measurement target according to the wavelength of each sawtooth wave detected by this signal processing means 20. Displacement data generating means 30 for generating displacement data of the object.

Moreover, the signal processing means 20 detects the upper and lower envelopes of the sawtooth wave, and the envelope detecting unit 21 based on the upper and lower envelopes detected by the envelope detecting unit 21. The intermediate line extraction unit 22 that extracts a substantially intermediate level of the intermediate line as an intermediate line, and the upper or lower area formed by the intermediate line extracted by the intermediate line extraction unit 22 and the sawtooth wave for each wave. Area calculation unit 23 for calculating
And a sawtooth wave identification unit 24 that identifies a wave having the area as an effective sawtooth wave when the area calculated by the area calculation unit 23 is larger than a predetermined area.

FIG. 4 is an explanatory diagram showing an example of calculating the area in the configuration shown in FIG. As shown in FIG. 4, the area calculation unit 23 divides the sawtooth wave k into upper and lower parts by the intermediate line obtained from the envelope h. Then, as shown in FIG. 4A, the area formed on the upper side by the sawtooth wave k and the intermediate line c is calculated. Further, as shown in FIG. 4 (B), it may be on the lower side.

Here, since the sawtooth wave is divided after the intermediate line c is obtained, the characteristics of the sawtooth wave are impaired even when the level of the sawtooth wave is entirely changed due to the fluctuation of the voltage level. The sawtooth wave can be specified accurately without further, and since the area is calculated by the area calculation unit 23 and this is compared with a predetermined constant area, even if the intermediate line c is crossed by noise. , It can be effectively removed.

Further, when the voltage level changes little, it is possible to perform the processing without dividing the center line. In this case, the signal processing means 20 includes an envelope detection unit 21 that detects one of the upper and lower envelopes of the sawtooth wave.
And an area calculation section 23 for calculating the area formed by the envelope detected by the envelope detection section 21 and the sawtooth wave for each wave.

When the envelope detecting unit 21 extracts the lower envelope h, the area formed below the sawtooth wave is calculated as shown in FIG. 5 (A). On the other hand, when the envelope detection unit 21 extracts the upper envelope, the area formed on the upper side of the sawtooth wave is calculated as illustrated in FIG.

Next, the operation of the displacement data generating means 30 will be described with reference to FIGS. 6 and 7. As shown in FIG. 6, one sawtooth wave has a displacement λ / of the vibration surface of the measurement object.
Corresponds to 2. From the sawtooth wave shown in FIG. 6, it can be measured that the vibration plane displacement is generated as shown in the figure. When the vibrating surface is displaced at high speed, the wavelength of the sawtooth wave becomes short, while when the wavelength is long, it is displaced slowly. In the example shown in FIG. 6, the wave number is counted based on the time when the sawtooth wave crosses the center line upward.

FIG. 7 is an explanatory diagram showing an example of the case where a voltage level variation and noise occur in a sawtooth wave. When the area calculator 23 shown in FIG. 3 calculates the area of the sawtooth wave shown in FIG. 7, the area becomes as shown in FIG. Since the noise portion intersects with the center line, if the wave number is counted by the method shown in FIG. 6, the number larger than the original wave number will be counted.
As shown in, when the area is calculated and the waveform having an area equal to or smaller than the predetermined constant area is discarded, the inconvenience of counting the noise portion does not occur.

Further, in the example shown in FIG. 7, when the area is less than a predetermined arbitrary size (threshold value), it is not treated as an intersection, so that the wavelength of the waveform portion discarded as noise is immediately before. Will be added to the wavelength.

The timing for calculating the area is when the sawtooth wave crosses the center line c from the top to the bottom or when it crosses the center line c from the bottom to the top. When calculating the area shown in FIG. 5, the area may be calculated at the peak of the sawtooth waveform. Further, the area may be calculated when the set voltage is uniformly exceeded.

In the example shown in FIG. 7, the timing treated as an intersection is based on the intermediate line. As described above, the timing of plotting the vibration plane displacement from the sawtooth wave is set at the time of intersection with the intermediate line, the peak of the sawtooth wave, or when the set voltage is exceeded, as in the calculation of the area.

Further, even when the area is calculated not at the portion divided by the intermediate line c but at the portion formed by the envelope h, the intersection of the intermediate line c and the sawtooth wave may be counted.

In this case, the envelope detecting section 21 has a function of detecting the upper and lower envelopes of the sawtooth wave. And
The envelope detection unit 21 is provided with an intermediate line extraction unit 22 that extracts a substantially intermediate level of the envelope based on the upper and lower envelopes detected by the envelope detection unit 21 as an intermediate line. Further, when the displacement data generating means 30 crosses the center line extracted by the intermediate line extracting unit 22 with the effective sawtooth wave specified by the sawtooth wave specifying unit 24 in the upward or downward direction. A centerline counting function for counting the waveform is provided.

As described above, in this embodiment, the intermediate line c generated based on the envelope h is used for both the area calculation and the wave number counting. As a result, even if the voltage level is changed, this effect can be effectively removed.

Further, in the example shown in FIG. 7, an example in which the vibrating surface is displaced in one direction is shown, but the processing by area is similarly performed in the case of switching the direction of displacement.
At this time, since the area of the portion where the direction switching occurs is small, it is preferable to change the predetermined area based on the determination result by the direction switching determination unit that is separately provided. Furthermore, if the area is not divided by the intermediate line but is large by the envelope, a difference in area with other portions is unlikely to occur even when the direction is changed. In some cases, it may be advantageous to remove noise based on the area of the envelope (see FIG. 12).

FIG. 8 is a block diagram showing the configuration of the hardware resources of the second embodiment.

As shown in FIG. 8, the vibration measuring apparatus includes a photodiode serving as a sensor head 41 and an amplifier 4 for amplifying a sawtooth wave detected by the photodiode 41.
2, an A / D converter 43 for converting the signal amplified by the amplifier 42 into digital data, and the A / D converter 43
A memory 44 that stores the digital data converted by the D converter 43 and a microcomputer 45 that counts the wave number of the sawtooth wave that is the digital data stored in the memory 44 are provided. FP instead of this microcomputer 45
The signal processing means 20 may be realized by a digital circuit such as GA. FPGA is Field Programmable G
Abbreviation of ate Array, which is an integrated circuit that allows the user to freely rewrite the internal circuit configuration.

FIG. 9 is a flow chart showing an operation example of the vibration measuring apparatus using the hardware resources shown in FIG.

First, the sawtooth wave is converted into digital data and stored in the memory 44 (step S21). The envelope of the sawtooth wave is identified from the waveform data of the memory 44 (step S22), and the intermediate voltage level is set as the central level for counting the wave number (step S23).

Further, a sawtooth wave higher than the center level is taken out and the area divided by the center level is calculated (step S24). A waveform having an area smaller than a predetermined area is not treated as a sawtooth wave. That is, the counting of the wave number based on the waveform is invalidated (step S
24). Since the area of noise is small, it is possible to effectively prevent erroneous measurement without counting the wave number. Then, when the effective waveform crosses the central level, it is counted as the wave number (step S27). Further, when the waveform crosses the center level, the time is recorded and the wave number is counted (step S27).

As described above, according to the present embodiment, the center level is calculated from the envelope of the sawtooth wave, the invalid waveform is selected according to the area of the waveform divided by this, and when the effective waveform crosses the center level. Since it is counted as the wave number, the accurate displacement measurement can be performed without erroneously counting the wave number even if the voltage level of the sawtooth wave fluctuates or noise is added to the signal.

[0048]

Since the present invention is constructed and functions as described above, according to the present invention, in the invention according to claim 1, the area calculating step is performed on the area formed by the intermediate line and the input waveform signal. The portion or lower portion is calculated, and the waveform identification step identifies only the waveform having an area larger than a predetermined area as an effective waveform. Therefore, the intersection number calculation step removes the influence of noise to determine the number of intersections. Therefore, it is possible to provide an unprecedented excellent waveform counting method capable of counting the number of generated waveforms by effectively eliminating the influence of voltage level fluctuations and noises.

In the invention according to claim 2, since the sawtooth wave specifying portion specifies a sawtooth wave having a predetermined area or more as a counting target, the sawtooth wave is effectively removed by fluctuation of the voltage level and noise. It is possible to identify one wave of the sawtooth wave, and further, the displacement data generating means measures the object to be measured based on the wavelength of the sawtooth wave from which the influence of the noise identified by the sawtooth wave identifying unit is removed. Since the displacement of the object is obtained, it is possible to provide an excellent vibration measuring device which has been heretofore capable of accurately measuring the displacement of the measuring object in a non-contact manner.

[Brief description of drawings]

FIG. 1 is a flowchart showing a configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of an input signal that is a target for counting the number of waves according to the flowchart of FIG.

FIG. 3 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an example of area calculation using an intermediate line, and FIG. 4A is a diagram for calculating an upper area.
(B) is a figure which calculates the area of a lower side.

5 is an explanatory diagram showing an example of area calculation using an envelope, and FIG. 5A is a diagram for calculating the area on the lower side, and FIG.
(B) is a diagram for calculating the upper area.

FIG. 6 is an explanatory diagram showing a relationship between an input waveform signal and displacement of a vibrating surface.

FIG. 7 is an explanatory diagram showing an example of signal processing in the case where an influence of fluctuation of a power supply level and an influence of noise are added to an input waveform signal.

8 is a block diagram showing a configuration of hardware resources of the vibration measuring device shown in FIG.

9 is a flowchart showing the operation of the configuration shown in FIG.

FIG. 10 is an explanatory diagram showing a schematic configuration of a vibration measuring device.

FIG. 11 is an explanatory diagram showing an example of a sawtooth wave affected by a change in voltage level.

FIG. 12 is an explanatory diagram showing an example of a sawtooth wave including a portion in which the displacement direction of the vibration surface is switched.

[Explanation of symbols]

10 Light detection means 20 Signal processing means 21 Envelope detection unit 22 Intermediate line extraction unit 23 Area calculator 24 Sawtooth wave identification part 30 displacement data generation means

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Claims (4)

(57) [Claims] 1. A measurement step of measuring a variation amount of an input signal input from a measurement object through various media, and a number of times the waveform measured in this measurement step intersects with a predetermined reference value, In a waveform counting method comprising a crossing number counting step of counting according to a reception time, before and after the crossing number counting step after the measuring step, the upper and lower envelopes of the input signal measured in the measuring step are Envelope detection step to detect, an intermediate line extraction step of extracting a substantially intermediate level of the envelope as an intermediate line based on the upper and lower envelopes detected by the envelope detection step, and the intermediate line extraction step An area calculation step of calculating, for each wave, an area formed for each wave on the upper part or the lower part of the intermediate line by the formed intermediate line and the input signal waveform measured in the measurement step, and by the area calculation step When a predetermined area is larger than a predetermined area, a waveform specifying step of specifying one wave of the area as an effective waveform to be counted is provided, and the intersecting number counting step is extracted by the intermediate line extracting step. A waveform counting method, characterized in that the intermediate line is counted when the intermediate line intersects the waveform identified in the waveform identifying step in an upward direction or a downward direction with the intermediate line as a reference value. 2. Light detection means for observing the laser light reflected from the object to be measured, and signal processing means for analyzing the waveform signal output from this light detection means and detecting a predetermined effective sawtooth wave. In a vibration measuring device provided with a displacement data generating unit that generates displacement data of the measurement object according to the wavelength of each sawtooth wave detected by the signal processing unit, the signal processing unit, An envelope detecting section for detecting the upper and lower envelopes of the sawtooth wave, and an intermediate line extracting section for extracting a substantially intermediate level of the envelope as an intermediate line based on the upper and lower envelopes detected by the envelope detecting section. And an area calculation unit that calculates the upper or lower area formed by the intermediate line extracted by this intermediate line extraction unit and the sawtooth wave for each wave, and the area calculated by this area calculation unit Vibration measurement apparatus comprising the sawtooth wave identification unit that identifies a wave having the area is larger than a predetermined area as an effective sawtooth wave. 3. Light detection means for observing the laser light reflected from the object to be measured, and signal processing means for analyzing the waveform signal output from this light detection means and detecting a predetermined effective sawtooth wave. In a vibration measuring device provided with a displacement data generating unit that generates displacement data of the measurement object according to the wavelength of each sawtooth wave detected by the signal processing unit, the signal processing unit, An envelope detecting section for detecting the envelope of the sawtooth wave, an area calculating section for calculating the area formed by the envelope and the sawtooth wave detected by the envelope detecting section for each wave, When the area calculated by the area calculation unit is larger than a predetermined area, a vibration measuring device comprising a sawtooth wave specifying unit that specifies a wave having the area as an effective sawtooth wave. . 4. The envelope detecting unit has a function of detecting upper and lower envelopes of the sawtooth wave, and the envelope detecting unit is configured to detect the upper and lower envelopes based on the upper and lower envelopes detected by the envelope detecting unit. And an intermediate line extraction unit for extracting a substantially intermediate level of the envelope as an intermediate line, and the displacement data generation unit uses the sawtooth wave identification unit with respect to the center line extracted by the intermediate line extraction unit. 4. The vibration measuring device according to claim 3, further comprising a center line counting function for counting the identified effective sawtooth wave when it crosses in the upward or downward direction.