JP4310479B2 - Dynamic linearity measuring method and measuring apparatus using laser interferometer of laser displacement meter - Google Patents

Description

  The present invention relates to a measurement method for evaluating the dynamic linearity of these measuring instruments, which is the basis of dynamic measurement using a laser displacement meter widely used in industry, and an apparatus for carrying out the method. The present invention is based on the results of measuring the dynamic displacement and speed generated by a micro-displacement generator in a high-speed and wide-frequency band from new DC to the required frequency, based on the results of measurement with a standard laser interferometer. The present invention relates to a measurement method capable of measuring the dynamic linearity of a target laser displacement meter and an apparatus for carrying out the method.

  Laser vibrometers and laser displacement meters that measure dynamic displacement and vibration based on the principle of optical interference such as Doppler shift and optical heterodyne interference have been widely used in the industry. Laser vibrometers and laser displacement meters can measure minute movements and dynamic displacements of minute surfaces in a non-contact manner, and in recent years, they have been widely used in the development of micro motion devices and micro motion mechanisms. ing.

  However, although the frequency bandwidth value far exceeding 1 MHz is shown in the manufacturer's specifications, there is no method for verifying the reliability of the measurement result at the frequency of interest in actual measurement. Data remains undisclosed. In other words, there is no way to verify whether laser vibrometers and laser displacement meters have a frequency bandwidth that well exceeds 1 MHz, and how much sensitivity and phase delay are at a specific frequency. It's real.

  Therefore, it is an urgent task to establish a measurement technique for evaluating the dynamic linearity that should be the basis of the dynamic performance of the laser vibrometer and the laser displacement meter, which will be used more frequently in the dynamic measurement.

  Therefore, the present invention measures whether or not dynamic linearity is established in these measuring devices in the measurement of dynamic displacement with a laser displacement meter, and also reveals the frequency domain and amplitude domain in which dynamic linearity is established. It is an object of the present invention to provide a measuring method and an apparatus for carrying out the method.

  In general, if the linearity of the measuring instrument does not hold, measurement will not be performed. Linearity in dynamic measurement, that is, dynamic linearity is: `` When the output signal for the input signal x (t) is X (t) and the output signal for the input signal y (t) is Y (t), it is arbitrary Using the constants a and b, the output signal for the input signal a · x (t) + b · y (t) must be a · X (t) + b · Y (t). Is generally defined. However, it is generally not easy to evaluate the dynamic linearity of measuring instruments and sensors based on this definition. Therefore, in the present invention, the dynamic linearity of the laser displacement meter is measured by the means described below.

  That is, with respect to the laser displacement meter, the laser beam from the laser displacement meter that measures the dynamic linearity and the laser interferometer serving as a reference is irradiated onto the end surface of the metal rod. The laser that serves as a reference for the dynamic displacement of the end face that occurs when the elastic wave pulse generated by colliding the inner projectile launched from the inner launch tube with the other end face of the rod reaches the other end face Measurements are made simultaneously with an interferometer and a laser displacement meter that measures dynamic linearity.

The dynamic displacement signal obtained by the reference laser interferometer is d _{n, 1} (t), and the dynamic displacement signal obtained by the laser displacement meter for evaluating the dynamic linearity is d _{t, 1} (t ). Next, the dynamic displacement of the end face caused when the elastic wave pulse generated by colliding the outer projectile launched from the outer launch tube with the end face of the rod reaches the other end face is used as a reference laser interference. Simultaneous measurement is performed with a laser displacement meter that evaluates the dynamic linearity of the meter. The dynamic displacement signal obtained with the reference laser interferometer is d _{n, 2} (t), and the dynamic displacement signal obtained with the laser displacement meter for evaluating the dynamic linearity is d _{t, 2} (t ).

Finally, the inner flying object and the outer flying object collide with the metal rod at the same time, and the dynamic displacement of the end surface that occurs when the generated elastic wave pulse reaches the other irradiation end surface is compared with the reference laser interferometer and motion. Simultaneous measurement with a laser displacement meter that measures the linearity. The dynamic displacement obtained with the reference laser interferometer is d _{n, 1 + 2} (t), and the dynamic displacement signal obtained with the laser displacement meter that evaluates the dynamic linearity is d _{t, 1 + 2} (t).

Since the wave generated inside the rod is an elastic wave, the additivity of the input signal, i.e. d _{n, 1 + 2} (t) = d _{n, 1} (t ) + d _{n, 2} (t) within the range where d _{t, 1 + 2} (t) = d _{t, 1} (t) + d _{t, 2} (t) A method of _{obtaining in the} domain or _comparing d _{t.1 + 2} (t) with d _{t, 1} (t) + d _{t, 2} (t) in the frequency domain and the time domain is used.

  When launching simultaneously, the projectile from the inner launch tube and the projectile from the outer launch tube have the same shape and the same conditions (launch pressure, initial position inside the launch tube) Etc.).

  If the inner flying object and the outer flying object do not collide with the rod at the same time, the time difference (Δt) is used as a parameter to determine Δt so as to best represent the signals when the two flying objects are fired simultaneously.

  Therefore, the present invention can solve the above-mentioned problems of the present invention by adopting the following means. That is, according to the first aspect of the present invention, only the first flying object, only the second flying object, and both the first and second flying objects collide with the first end surface of the metal rod simultaneously or with a slight time difference. Then, an elastic wave pulse is generated inside the metal rod, and the dynamic displacement of the second end surface that occurs when the elastic wave pulse generated by each collision reaches the second end surface opposite to the first end surface of the metal rod. Is measured by a laser interferometer and a laser displacement meter to be evaluated, and the laser interferometer signal and the laser displacement meter signal are compared in the time domain or the frequency domain. This is a dynamic linearity measuring method using a laser interferometer of a laser displacement meter characterized by measuring the dynamic linearity of the laser.

  According to the second aspect of the present invention, only the first flying object, only the second flying object, and both the first and second flying objects collide with the first end surface of the metal rod simultaneously or with a slight time difference. And a launching device for generating an elastic wave pulse inside the metal rod, and a second end surface generated when the elastic wave pulse generated by each collision reaches the second end surface opposite to the first end surface of the metal rod. A laser interferometer that measures dynamic displacement, a laser displacement meter to be evaluated, a signal of the laser interferometer, and a signal of the laser displacement meter are compared in the time domain or the frequency domain, and the laser displacement meter This is a dynamic linearity measuring apparatus using a laser interferometer of a laser displacement meter, characterized by comprising a measuring means for measuring dynamic linearity.

  According to a third aspect of the present invention, the first projectile is fired from the inside of the inner tube, and the second projectile is fired from between the inner tube and the outer tube, or vice versa. 3. The dynamic linearity using the laser interferometer of the laser displacement meter according to claim 2, wherein the flying object is emitted from between the inner tube and the outer tube, and the second flying object is emitted from the inner tube. This is a sex measuring device.

  According to a fourth aspect of the present invention, the first flying body and the launching device therefor, the second flying body and the launching device therefor are multiplexed, the time difference between launches is controlled, and the elasticity generated inside the metal rod 3. The dynamic linearity measuring apparatus using a laser interferometer of a laser displacement meter according to claim 2, wherein the wave frequency band is narrowed.

  Further, in the invention according to claim 5, the flying body main body is formed of a laminate of different materials, or a member made of a material different from the main body is attached to the tip of the flying body main body, and the elasticity generated inside the metal rod. 3. The dynamic linearity measuring apparatus using a laser interferometer of a laser displacement meter according to claim 2, wherein the frequency band of the wave pulse is controlled.

  Further, in the invention according to claim 6, when the measurement means causes the first and second flying bodies to collide with a minute time difference, the difference between the collision times of the two flying bodies with respect to the metal rod is obtained by using both flying bodies. Strain gauge output generated when each projectile collides with a small time difference based on the result of measurement by a laser interferometer or the result of measurement using a laser interferometer. Alternatively, the measurement result obtained by the reference laser interferometer is obtained as the most suitable parameter, and the evaluation object is obtained when only the first flying object, only the second flying object, and both flying objects collide with each other with a minute time difference. The dynamic linearity measurement using the laser interferometer of the laser displacement meter according to claim 2, wherein the dynamic linearity is measured from the output signal of the laser vibrometer. It is a device.

  The invention according to claim 7 is characterized in that the metal rod is horizontally supported by point contact so as not to constrain the rigid body motion in the axial direction. This is a dynamic linearity measuring apparatus using a meter.

  According to an eighth aspect of the present invention, a metal sphere in contact with the first end surface of the metal rod is attached, and a flying object whose launch timing is precisely controlled is collided with the metal sphere to generate an elastic wave pulse inside the metal rod. The dynamic linearity measuring apparatus using the laser interferometer of the laser displacement meter according to claim 2, wherein

  The invention according to claim 10 is a laser displacement meter in which dynamic linearity is measured using the apparatus or method according to any one of claims 1 to 9.

  According to the present invention, in the measurement of dynamic displacement with a laser displacement meter, whether or not dynamic linearity is established in those measuring devices is measured, and the frequency region and amplitude region in which dynamic linearity is established are clarified. A measurement method and a device for carrying out the method can be obtained.

  Thereby, it contributes to the establishment of the primary standard and the secondary standard of the laser displacement meter, and can contribute to the establishment of the international standard in this field. In addition, the reliability of high-frequency vibration measurement in microdevices and micromechatronics can be improved, and the reliability of the primary standard calibration technology for acceleration sensors can also be improved, and international standards can be created. .

  In addition, it improves the reliability of calibration standards for dynamic mechanical quantity sensors in the company, thereby improving the reliability of dynamic mechanical quantity measurement and distinguishing between noise and signal when using each measuring instrument. It is possible to solve practical problems such as absence.

  In the measurement of dynamic displacement using a laser displacement meter, the present invention measures whether or not dynamic linearity is established in the measuring device, and also clarifies the frequency region and amplitude region where dynamic linearity is established. A method and an apparatus for carrying out the method are provided as follows: a first end of a metal rod, only a first projecting object, only a second projecting object, and both the first and second projecting objects. At the same time or with a small time difference to generate an elastic wave pulse inside the metal rod, and the elastic wave pulse generated by each collision reaches the second end surface opposite to the first end surface of the metal rod. The dynamic displacement of the second end face is measured by the laser interferometer and the laser displacement meter to be evaluated, and the signal of the laser interferometer and the signal of the laser displacement meter are compared in the time domain or the frequency domain. By doing It was achieved by measuring the dynamic linearity of the chromatography The displacement meter.

  Since the dynamic linearity measurement method and apparatus using the laser interferometer of the laser displacement meter according to the present invention can be implemented in various modes other than the present invention by substantially the same technique, various methods related to the present invention are provided. A description will be given including aspects. In the embodiment shown in FIG. 1, a flying object 3 as will be described later is collided with the first end face 2 of the metal rod 1 to apply an impact, and an elastic wave pulse is generated inside. A double multiple launch tube 7 of the outer launch tube 5 is used, and two multiple projectiles 3 inside and outside are fired from the multiple launch tube 7. In the illustrated embodiment, a substantially cylindrical inner projecting body 8 is formed from the inside of the inner projecting tube 4 by the inner projecting device 9, and an annular outer projecting body 10 is formed from the annular space between the inner projecting tube 4 and the outer projecting tube 5. Each of the outer firing devices 11 can fire independently. In this firing state, the laser beam from the laser light source 27 is irradiated in front of the metal rod 1 at two intervals, the state where the laser beam is blocked is detected by the light receiving element 28, and the time difference is measured by the counter 29. The data can be input to the personal computer 26 and detected.

  When each of the flying objects is fired, the valve opening / closing control device 15 releases the first valve 16 and supplies the high-pressure air from the first high-pressure air source 17 to the inner launching device 9, thereby The inner flying object 8 is fired toward the first end face 2 of the metal rod 1. When the inner flying object 8 collides with the first end face 2 of the metal rod 1, an elastic wave of impact acceleration is generated in the metal rod 1 and propagates through the metal rod 1. Further, the valve opening / closing control device 15 releases the second valve 18 after a predetermined time after the release of the first valve 16, and supplies the high-pressure air from the second high-pressure air source 19 to the outer launching device 11. An annular outer flying body 10 disposed between the launch tube 4 and the outer launch tube 5 is fired toward the first end face 2 of the metal rod 1. When the outer flying object 10 collides with the first end face 2 of the metal rod 1, an elastic wave having the same impact acceleration as that described above is generated in the metal bar 1 with respect to the generation of the elastic wave due to the collision of the first flying object 8. It occurs with a delay and propagates through the metal rod 1.

  Due to the elastic wave generated in the metal rod 1 in this way, a waveform of the combined impact acceleration is generated in the metal rod 1, and this waveform propagates to the second end face 22 of the metal rod 1. In this way, by using multiple projectiles and arbitrarily setting the launch timing of each projectile and controlling the phase of launch, it is possible to generate an impact acceleration waveform with a predetermined duration as a whole by the principle of superposition It becomes possible.

  It is preferable to provide a lubrication treatment or a surface treatment layer for reducing the coefficient of friction on the contact surfaces of the launching tubes 4 and 5 with the flying bodies 8 and 10 or on the outer peripheral surface of each flying body. Further, in order to narrow the frequency band of the elastic wave pulse generated inside the metal rod 1 by the firing of each flying object, a polymer material, plastics, wood or the like may be attached to the flying object tip. In that case, a multiple flying body in which the flying body main body has a laminated structure with different materials such as metal, polymer material, plastics, and wood may be used. The metal rod 1 is preferably supported horizontally by point contact such as a ball bearing or a roller bearing so as not to restrict the rigid body motion in the axial direction, and the influence on the propagation of the elastic wave is minimized. Furthermore, you may attach in the state which contacts the metal ball to the end surface of the metal rod which a flying body collides.

  The elastic wave pulse generated on the first end surface 2 of the metal rod 1 as described above propagates through the metal rod 1 and reaches the other second end surface 22 to be reflected. The dynamic displacement in the direction perpendicular to the end face generated in the reflection process becomes an input to the laser displacement meter 23 that irradiates the end face with laser. Further, the precise measurement of the dynamic displacement is measured by the laser interferometer 24, and is compared with the measured value by the laser displacement meter that is the measurement target of the dynamic linearity.

  In the present invention, measurement by a laser displacement meter can also be performed and evaluated using an apparatus as shown in FIG. In the example shown in the figure, unlike the example shown in FIG. 1, a piezoelectric film or a laser beam reflecting film (material) (hereinafter referred to as “piezoelectric film”) 30 is provided on the second end face 22 of the metal rod 1. In the example of FIG. 2, the strain gauge signal is detected and processed by the signal input processing unit 31, and the piezoelectric film driving device 32 is operated so that the piezoelectric film 30 can be driven. Further, the laser of the laser displacement meter 23 to be evaluated and the laser of the laser interferometer 24 to be the reference irradiate the surface of the piezoelectric film 30 through the mirror 33, and the piezoelectric film 30 and the metal rod 1 The generated dynamic displacement can be detected. Further, the piezoelectric film can be driven at a predetermined time according to an instruction from the personal computer 26.

  When such a piezoelectric film is used, if the velocity generated by reflection at the end face of the elastic wave pulse propagating inside the round bar and the frequency band of dynamic displacement are not wide enough, add a piezoelectric substance to the cross section. It is possible to increase the bandwidth. The use of this piezoelectric material will be described later. In the apparatus as shown in FIG. 2, at least one of wave dispersion, wave attenuation, sonic value uncertainty, gauge frequency response, high-speed microvibration of the piezoelectric material attached to the rod end face, and high-speed microdynamic displacement. By using the data that records the correction function to correct the error and the metal bar with the strain gauge attached as an indispensable replacement part set, it is easy to handle this device as a device that can be easily repeated. Can be.

(8.1) When measuring the dynamic displacement of the rod end surface using a reference laser interferometer to determine the dynamic linearity of the laser displacement meter.
In this case, when the flying object launched from the launch tube collides with the end face of the metal rod that is sufficiently longer than the diameter, an elastic wave pulse is generated inside. When the elastic wave pulse reaches the other end surface and is reflected, the dynamic displacement (d (t)) of the end surface is determined by the longitudinal elastic wave velocity (C) inside the metal rod and the incident elastic wave at the end surface. It is expressed by the following equation depending on the pulse distortion (ε (t)).

(8.1)

(8.2)

(8.3) Therefore, the dynamic displacement generated on the end face when the projectile is launched from the inner launch tube and the distortion of the incident elastic wave pulse are d _{in, 1} (t) and ε _{in, 1} (t), respectively. Let d _{in, 2} (t) and ε _{in, 2} (t) be the dynamic displacement generated at the end face when the projectile is launched from the outer launch tube and the distortion of the incident elastic wave pulse, respectively. The following equation holds.

(8.2)

(8.3)

(8.4)式が成立する範囲内で、(8.5) 式が成立する周波数範囲、動的変位範囲を明らかにすることが評価対象であるレーザ変位計の動的線形性の評価である。

(8.4)

(8.5) Therefore, the symbols are determined as shown in the following table.

The evaluation of the dynamic linearity of the laser displacement meter that is the object of evaluation is to clarify the frequency range and dynamic displacement range in which equation (8.5) is satisfied within the range in which equation (8.4) is satisfied.

(8.4)

(8.5)

(8.6)

(8.7) If the time difference between the inner projectile and the outer projectile is not simultaneous, Δt, the frequency range and dynamic displacement range in which (8.7) is established within the range in which (8.6) is satisfied. This is the evaluation of the dynamic linearity of the laser displacement meter that is the object of evaluation.

(8.6)

(8.7)

  When the velocity generated by reflection at the end face of the elastic wave pulse propagating inside the round bar and the frequency band of dynamic displacement are not wide enough, a piezoelectric substance (piezoelectric film, piezoelectric stack, etc.) is added to the end face, Increase bandwidth. In this case, this piezoelectric material is used as follows.

  As described above, in the present invention, the laser beam irradiation end face of the metal rod is used only when either the projectile is fired from the inner launch tube only or the projectile is launched only from the outer launch tube. Drive the piezoelectric material attached to. When the inner flying object and the outer flying object are simultaneously fired, the piezoelectric material is driven under the same conditions as when fired individually.

It is a block diagram which shows the system outline | summary which implements this invention. It is a block diagram which shows the other system outline | summary which implements this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal rod 2 1st end surface 3 Flying object 4 Inner launch tube 5 Outer launch tube 6 Multiple launch tube 7 Inner projectile 8 Inner launch device 10 Outer projectile 11 Outer launch device 15 Valve opening / closing control device 16 First valve 17 First High pressure air source 18 Second valve 19 Second high pressure air source 22 Second end face 23 Laser displacement meter
24 laser interferometer 26 personal computer 27 laser light source 28 light receiving element 29 counter 30 piezoelectric material having a mirror surface (piezoelectric film)
31 Signal Conditioner 32 Piezoelectric Film Drive 33 Mirror

Claims (10)

An elastic wave pulse is generated inside the metal rod by causing the first end of the metal rod to collide with only the first projectile, only the second projectile, and both the first and second projectiles simultaneously or with a slight time difference. Generate
The dynamic displacement of the second end face that occurs when the elastic wave pulse generated by each collision reaches the second end face on the opposite side of the first end face of the metal rod is measured using a laser interferometer and a laser displacement to be evaluated. Measure with a meter,
The laser interference of the laser displacement meter is characterized by measuring the dynamic linearity of the laser displacement meter by comparing the signal of the laser interferometer and the signal of the laser displacement meter in the time domain or the frequency domain. Dynamic linearity measurement method using a meter. An elastic wave pulse is generated inside the metal rod by causing the first end of the metal rod to collide with only the first projectile, only the second projectile, and both the first and second projectiles simultaneously or with a slight time difference. A launcher for generating,
A laser interferometer that measures the dynamic displacement of the second end face that occurs when the elastic wave pulse generated by each collision reaches the second end face opposite to the first end face of the metal rod, and a laser to be evaluated A displacement meter;
A laser displacement comprising: a measuring means for comparing a signal of the laser interferometer and a signal of the laser displacement meter in a time domain or a frequency domain and measuring a dynamic linearity of the laser displacement meter. Dynamic linearity measuring device using a laser interferometer.   The launcher comprises a double tube, and the first projectile is fired from inside the inner tube, and the second projectile is fired from between the inner tube and the outer tube, or vice versa. 3. The dynamic linearity using the laser interferometer of the laser displacement meter according to claim 2, wherein the flying object is emitted from between the inner tube and the outer tube, and the second flying object is emitted from the inner tube. Sex measuring device.   Multiplexing the first projectile and the launching device therefor, the second projectile and the launching device therefor, controlling the time difference between launches, and narrowing the frequency band of the elastic wave generated inside the metal rod; A dynamic linearity measuring apparatus using the laser interferometer of the laser displacement meter according to claim 2.   It is possible to control the frequency band of the elastic wave pulse generated inside the metal rod by configuring the flying body main body with a laminate of different materials, or attaching a member of a different material from the main body to the tip of the flying body main body. A dynamic linearity measuring apparatus using the laser interferometer of the laser displacement meter according to claim 2.   When the first and second projectiles collide with each other with a minute time difference, the measuring means generates a difference in collision time between the projectiles and the metal rod when the projectiles collide with each other independently. Based on the measurement result by the laser interferometer, the measurement result by the reference laser interferometer generated when the projectiles collide with a minute time difference because the simultaneous collision cannot be achieved completely is obtained as the most suitable parameter. Measure the dynamic linearity from the output signal of the laser displacement meter that is the object of evaluation obtained when the projectile alone and the second projectile alone, and the two projectiles collide with each other with a minute time difference. A dynamic linearity measuring apparatus using the laser interferometer of the laser displacement meter according to claim 2.   3. The dynamic linearity measuring apparatus using a laser interferometer of a laser displacement meter according to claim 2, wherein the metal rod is horizontally supported by point contact so as not to restrain the rigid body motion in the axial direction. . A metal sphere in contact with the first end surface of the metal rod is attached,
The movement using the laser interferometer of the laser displacement meter according to claim 2, wherein a flying object with precisely controlled launch timing is caused to collide with the metal sphere to generate an elastic wave pulse inside the metal rod. Linearity measuring device. A piezoelectric material is attached to the second end face of the metal rod,
Piezoelectric material driving means for driving the piezoelectric material at a predetermined time in the reflection process of the elastic wave pulse at the second end surface;
3. The laser according to claim 2, wherein when the frequency bandwidth of the dynamic displacement of the rod end surface that can be generated by a single metal rod is insufficient, the frequency bandwidth is widened by the piezoelectric material driving means. A dynamic linearity measuring device using a displacement laser interferometer.   A laser displacement meter in which dynamic linearity is measured using the apparatus or method according to any one of claims 1 to 9.

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