JP2003315360A - Dynamic characteristic measuring device of acceleration sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dynamic characteristic measuring device of an acceleration sensor capable of calibrating dynamic linearity with sufficient accuracy even in a DC type acceleration sensor. <P>SOLUTION: This device is equipped with a rod body such as a metal rod dropping in the vertical direction or in the oblique direction at an angle determined beforehand, capable of propagating an elastic wave, a means for allowing an object having comparatively low hardness such as aluminum or lead to collide with first one end of the rod body, a means for measuring the object speed by measuring the object speed by a method such as photoelectric measurement, a first acceleration detection means which is an accelerometer to be calibrated, capable of detecting the acceleration of movement of second one end of the rod body and a second acceleration detection means which is a standard accelerometer by a laser interferometer or the like, and a means for comparing the result of the first acceleration detection means with the result of the second acceleration detection means. The device is constituted so as to detect the acceleration of the movement of second one end of the rod body caused by an elastic wave generated by collision at the first one end of the rod body, by the first acceleration detection means and the second acceleration detection means respectively. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor dynamic characteristic measuring apparatus capable of calibrating an acceleration sensor which also detects a steady acceleration (DC acceleration) component.

[0002]

2. Description of the Related Art Acceleration sensors are used, for example, in vehicle suspensions, robots, transportation equipment, transportation systems, nuclear power generation related equipment, ships, aerospace equipment, micro motion devices, earthquakes, earthquake resistance of building structures, and civil engineering structures. It is used in fields such as earthquake resistance, minute vibrations of building structures (due to minute earthquakes and winds), and minute vibrations of civil engineering structures (due to minute earthquakes and winds), and detects only acceleration change components. It is known that there are an acceleration sensor and a DC acceleration sensor that detects a stationary acceleration component as well.

As a method of calibrating such an acceleration sensor, in addition to the method of using the gravity of the earth, 1) a method of creating a steady acceleration by using a centrifugal force on an object that makes a circular motion 2) There is a method of using acceleration that changes periodically on a vibrating object. The former is described in, for example, JP-A-07-110342, and the latter is described in, for example, JP-A-07-0555629.

However, not only the direct current (DC) type acceleration sensor but also the acceleration sensor as a whole can be said that even if the frequency characteristic including the resonance characteristic of the acceleration sensor itself is a problem, the dynamic linearity which is a premise thereof is used. Has not been verified. The dynamic linearity referred to here means that the additivity of the input signal is directly reflected in the output signal in the acceleration sensor under the transient state.

In the field of DC acceleration sensors,
The sensitivity of the acceleration sensor is too high compared to the straightness of motion for dynamic calibration, and the straightness of motion generated by the shaking table is insufficient, making it difficult to evaluate the effect of parasitic lateral vibration. For that reason, dynamic calibration has not been done.

[0006]

As described above, in the conventional calibration, the direct current (DC) type acceleration sensor is not calibrated for the dynamic linearity.

The present invention has been proposed in view of the above,
An object of the present invention is to provide an acceleration sensor dynamic characteristic measuring device capable of calibrating dynamic linearity with sufficient accuracy even in a DC type acceleration sensor.

[0008]

In order to achieve the above object, the first invention of the present invention relates to a device for measuring the dynamic characteristics of an acceleration sensor, especially its linearity,
A rod-shaped body such as a metal rod capable of propagating an elastic wave by falling vertically or obliquely at a predetermined angle and a first end of the rod-shaped body collide with a relatively low hardness object such as aluminum or lead And means for measuring the velocity of the object by measuring the velocity of the object by a method such as photoelectric measurement, and a calibration capable of detecting the acceleration of the movement of the second end of the rod-shaped body. And a second acceleration detecting means which is a reference accelerometer including a laser interferometer, a result of the first acceleration detecting means and a result of the second acceleration detecting means. The means for comparing and the acceleration in the movement of the second end of the rod-shaped body caused by the elastic wave due to the collision at the first end of the rod-shaped body are compared with the first acceleration detection means and the second acceleration detection means. so It is characterized in that it comprises a structure and detecting Re respectively.

A second aspect of the present invention is to generate an elastic wave in a rod-shaped body by an object group made of objects of the same material but different in number, in the vertical direction or at a predetermined angle. A rod-shaped body that is capable of propagating elastic waves by falling in an oblique direction, means for colliding each object group with the first end of the rod-shaped body, means for measuring the velocity of the object group, and the rod-shaped body described above. The first acceleration detecting means and the second acceleration detecting means capable of detecting the acceleration of the movement of the second end of the body, and the result of the first acceleration detecting means and the result of the second acceleration detecting means. The means for comparing and the acceleration in the movement of the second end of the rod-shaped body caused by the elastic wave due to the collision at the first end of the rod-shaped body are compared with the first acceleration detection means and the second acceleration detection means. Detected by each It is characterized in that it comprises.

A third aspect of the present invention uses a plurality of elastic wave pulses generated by a plurality of objects,
A rod-shaped body capable of propagating elastic waves that falls vertically or obliquely at a predetermined angle, a means for colliding a plurality of objects with a first end of the rod-shaped body, and the velocity of the object is measured. Means, a second acceleration detecting means using the first acceleration detecting means and an optical means capable of detecting the acceleration of the movement of the second end of the rod-shaped body, and the first acceleration detecting means. Means for comparing the result with the result of the second acceleration detecting means, and the rod-like shape caused by elastic waves caused by the respective collisions of the plurality of objects which are collided with the first end of the rod-shaped body with a time difference. It is characterized in that it is provided with a configuration in which the acceleration in the movement of the second end of the body is detected by the first acceleration detecting means and the second acceleration detecting means.

A fourth aspect of the present invention is to correct the result of the accelerometer by observing the shape of the elastic wave. In addition to the configuration of any one of the above-described first to third aspects, The elastic wave detecting means capable of detecting the elastic wave propagating in the rod-shaped body on the side surface of the rod-shaped body is further provided, and the elastic wave caused by the collision with the first end of the rod-shaped body is generated. A configuration in which the result of detecting the acceleration in the movement of the second end of the rod-shaped body by the first acceleration detecting means is corrected by the result of detecting the elastic wave by the elastic wave detecting means. There is.

According to a fifth aspect of the present invention, in addition to the configuration of the fourth aspect described above, the elastic wave detecting means is corrected by the result detected by the second acceleration detecting means. It is characterized by being a means.

The sixth aspect of the present invention is a structure which provides convenience for ignoring the influence of the mass of the acceleration sensor and applying any acceleration sensor having a common mounting method. In addition to the configuration of the fifth aspect of the invention, the means corrected by the result detected by the second acceleration detecting means is the elastic wave without the first acceleration detecting means provided on the rod-shaped body. Characterized in that it is a means including a correspondence between an elastic wave and an acceleration prepared by using a single or plural elastic wave detecting means provided on the outer periphery of a rod-shaped body on one plane orthogonal to the traveling direction of There is.

A seventh aspect of the present invention provides a more accurate correction using a correction function including the influence of the mass of the acceleration sensor, and in addition to the configuration of the fifth aspect described above. The means corrected by the result detected by the second acceleration detecting means includes a plurality of planes orthogonal to the traveling direction of the elastic wave, in which the first acceleration detecting means is provided on the rod-shaped body. It is characterized in that it is a means including correspondence between an elastic wave and an acceleration prepared by using a plurality of elastic wave detecting means provided on the outer periphery of the rod-shaped body above.

The eighth aspect of the present invention is to calibrate an accelerometer based on the detection result of an elastic wave by an elastic wave detector such as a strain gauge, and to calibrate the accelerometer vertically or obliquely at a predetermined angle. A rod-shaped body capable of propagating a falling elastic wave, means for colliding an object having a momentum with a first end of the rod-shaped body, means for measuring the velocity of the object, and propagating through the rod-shaped body. An elastic wave detecting means capable of detecting an elastic wave on the side surface of the rod-shaped body; a first acceleration detecting means capable of detecting the acceleration of the movement of the second end of the rod-shaped body; A means for comparing the result of the first acceleration detecting means and a result of the elastic wave detecting means, and a means for comparing the result of the collision with the first end of the rod-shaped body to generate a second elastic wave of the rod-shaped body. The acceleration in one end motion Detected by the first acceleration detecting means, and the above-described elastic wave; and a configuration for detecting each the above elastic wave detection means.

According to a ninth aspect of the present invention, in addition to the configuration of the eighth aspect described above, the detection result by the elastic wave detecting means corresponds to a previously determined characteristic of the elastic wave and acceleration. It is characterized by being corrected by the relationship.

The tenth invention of the present invention, in addition to the constitution of any one of the above-mentioned first to ninth inventions,
The object for generating various elastic waves is characterized in that the object that collides with one end of the rod-shaped body has a lower hardness at the tip of the collision portion than at other portions.

An eleventh invention of the present invention is for generating an elastic wave close to a plane wave, in addition to the structure of any one of the first to tenth inventions described above.
The means for colliding an object with the first end of the rod-shaped body is
It is characterized by having symmetry about the movement direction of the object.

The twelfth invention of the present invention is, in addition to the configuration of any one of the first to eleventh inventions described above, adjusts the timing of collision in order to generate an elastic wave having a narrow frequency band. Since it is necessary, the means for colliding the object with the first end of the rod-shaped body has a predetermined time interval so that the elastic wave generated in the rod-shaped body has a predetermined frequency band. The feature is that multiple objects collide.

The thirteenth invention of the present invention is to make a correction based on theoretical analysis. In addition to the configuration of the ninth invention described above, a means for correcting the result of the elastic wave detecting means is provided. , Which is a means in accordance with the elastic wave propagation theory, and which is used to obtain the transient distortion signal of the elastic wave pulse incident on the second end from the output signal of the elastic wave detecting means, at least the first order of analytical solutions It is characterized by including terms (Skalak's solution).

The fourteenth invention of the present invention is to compare using a spectrum analyzer, and in the configuration of any one of the first to thirteenth inventions described above,
The comparison between the result of the first acceleration detecting means and the result of the second acceleration detecting means is performed in the frequency domain.

The fifteenth invention of the present invention is to compare using a spectrum analyzer, and in the configuration of any one of the above fourth to thirteenth inventions,
The result of the above first acceleration detecting means or the above second result
The comparison between the result of the acceleration detecting means and the result of the elastic wave detecting means is performed in the frequency domain.

The sixteenth aspect of the present invention is to generate elastic waves of various intensities by using the overlapping of elastic waves, and any one of the above first to fifth or tenth to fifteenth aspects. In addition to the configuration of the invention described above, a configuration in which a plurality of objects collide with the first end described above, a configuration in which elastic wave pulses due to the collision of the plurality of objects have an overlap, and The first acceleration detecting means and the second acceleration detecting means are used for the detection.

A seventeenth aspect of the present invention is to eliminate the influence of gravitational acceleration. In addition to the configuration of any one of the first to sixteenth aspects of the invention described above, the rod-shaped body is allowed to fall freely. The feature is that elastic waves are generated and detected in the meantime.

The eighteenth invention of the present invention is such that the influence of the gravitational acceleration can be measured as a parameter, and in addition to the above-mentioned configuration of the seventeenth invention, the direction of the gravitational acceleration and the acceleration detected. It is characterized in that the angle in the direction of is at a predetermined value during the generation and detection of the elastic wave.

A nineteenth aspect of the present invention is to suppress the influence of the acceleration of motion in the direction perpendicular to the direction of the gravitational acceleration when measuring the influence of the gravitational acceleration as a parameter. In addition to the configuration of the seventeenth invention, the gravitational acceleration direction and the detected acceleration direction are parallel.

The twentieth aspect of the present invention is to utilize elastic waves having different intensities by using reflection and attenuation of the elastic wave. In addition to the configuration of any one of the first to nineteenth aspects of the present invention. The elastic waves reflected at both ends of the rod-shaped body are used.

The twenty-first invention of the present invention is to change the collision site when elastic waves are generated by a subsequent collision. In addition to the structure of any one of the first to sixteenth inventions, The elastic wave is generated and detected while the rod-shaped body and the object colliding with the first end of the rod-shaped body are relatively rotated around the movement direction of the colliding object.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. First, the principle of the present invention will be described, and then an example of a preferred embodiment will be described with reference to FIG.

In the following description, dynamic linearity is arbitrary 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). Using the constants a and b, the following input signal,

[0031]

[Equation 1] Output signal for

[0032]

[Equation 2] Then, it is said that the dynamic linearity holds.

(1) In the present invention, a metal rod is used as a rod having a center axis installed in the direction of gravitational acceleration, and an acceleration sensor to be measured is attached to the end face of the rod. The inner flying body is collided. The acceleration sensor is calibrated using the motion acceleration of the end face generated when the elastic wave pulse generated by this collision reaches the end face to which the acceleration sensor is attached.

For this purpose, first, the acceleration signal input to the acceleration sensor is input.

[Equation 3] And the output of the acceleration sensor,

[0035]

[Equation 4] And ask. Next, when the elastic wave pulse generated by the collision of the outer projectile emitted from the outer launch tube with the end face of the rod reaches the other end face, the motion acceleration of the end face, that is, the input acceleration signal to the acceleration sensor. ,

[0036]

[Equation 5] And the output of the acceleration sensor,

[0037]

[Equation 6] And ask.

Finally, when the inner flying body and the outer flying body are made to collide with the metal rod at the same time, the acceleration signal acting as an input signal to the acceleration sensor is defined by the elastic wave and its linearity.

[0039]

[Equation 7] Becomes At this time, the gauge output signal

[0040]

[Equation 8] And Assuming linearity holds, the output signal is

[0041]

[Equation 9] It should be. Therefore, conversely, it is understood that the dynamic linearity of the acceleration sensor can be measured in terms of gain and phase by comparing the signal represented by the equation 9 with the signal represented by the equation 8 in the frequency domain or the time domain. .

As a function of the time (t) generated when an elastic wave pulse generated when a projectile launched from a launch tube collides with the end face of a metal rod and reaches and reflects the end face with an acceleration sensor attached. The impulsive acceleration (a (t)) is expressed by the following equation by the longitudinal elastic wave velocity (C) inside the metal rod and the distortion (ε (t)) of the incident elastic wave pulse at the end face.

[0043]

[Equation 10] Therefore, the acceleration generated at the end face when the projectile is launched from the inner launch tube and the distortion of the incident elastic wave pulse are

[0044]

[Equation 11] And The acceleration and the distortion of the incident elastic wave pulse generated on the end face when the projectile is launched from the outer launch tube, respectively.

[0045]

[Equation 12] And At this time, the following formula is established.

[0046]

[Equation 13]

Further, since it is the movement velocity of the end face that can be measured by the laser interferometer, the movement velocity of the end face generated by each of the inner projectile and the outer projectile can be calculated.

[0048]

[Equation 14] Then, the following formula is established.

[0049]

[Equation 15]

Therefore, the laser is emitted when the inner projectile is independently launched, when the outer projectile is independently launched, and when the inner projectile and the outer projectile are simultaneously and independently launched. The speed of motion of the end face measured by the interferometer,

[0051]

[Equation 16] Then, the following formula is established.

[0052]

[Equation 17]

The output signal of the acceleration sensor at that time is

[0054]

[Equation 18] Then, the measurement of the dynamic linearity is to clarify the frequency range and the acceleration range in which the equation 20 is satisfied within the range in which the equation 19 is satisfied.

[0055]

[Formula 19]

[0056]

[Equation 20]

If the inner and outer projectiles do not collide at the same time, assuming that the time difference is Δt, Equation 21
The measurement of dynamic linearity is to clarify the frequency range and acceleration range where is satisfied.

[0058]

[Equation 21]

(2) Next, the case where the dynamic linearity of the DC type acceleration sensor is measured by using the gauge output (one) as it is will be described. Regarding the output signal of the strain gauge pasted at the distance L ₁ from the end face with which the flying object collides in the embodiment shown in FIG. 1, when the inner flying object is independently fired, when the outer flying object is independently fired, For each of the case where the projectile and the outer projectile are simultaneously and independently launched, and when launched under the same conditions,

[0060]

[Equation 22] And In this case, since the frequency response characteristics of the strain gauge, dispersion of elastic wave, attenuation, uncertainty of sound velocity value, etc. are not taken into consideration, the strain that is the output signal of the gauge is directly used as the strain of the elastic wave pulse incident on the acceleration sensor mounting surface. To be

The output signal of the acceleration sensor corresponding to Equation 22 is

[Equation 23] Then, it is the measurement of the dynamic linearity that the frequency range and the acceleration range in which the equation 25 is established are clarified within the range in which the equation 24 is established.

[0062]

[Equation 24]

[Equation 25]

When the collision of the inner flying object and the outer flying object is not the same, it is possible to measure the dynamic linearity by clarifying the frequency range and the acceleration range in which the equation (2.3) is established, where the time difference is Δt. is there.

[0064]

[Equation 26]

Next, a case will be described in which the dynamic linearity of the DC type acceleration sensor is measured using the outputs of a plurality of strain gauges as they are. A plurality of strain gauges in the axial direction of the metal rod from the impact end surface of the _{rod, L n (n = 1 ...} N)
It is assumed that they are affixed at positions that are distant from each other. In addition, the representative position of the gauge attached at a plurality of positions in the axial direction of the rod is L ₁ . In this case, at each L _n (n = 1 ... N) position, the incident wave and the reflected wave to the end face to which the acceleration sensor is attached must be observed separately.

From the theory of elastic wave propagation, the distortion of the elastic wave pulse in the cross section of the round bar sufficiently distant from the impact end face becomes a plane wave, and therefore the distance z from the impact end face and the time t (at t = 0, the collision of the flying object). Can be expressed analytically. Therefore, the strain inside the round bar as a plane wave is expressed by the following equation.

[0067]

[Equation 27] However, the right side of Expression 27 is expressed as follows. (Skalak's solution, the first item of series expansion)

[0068]

[Equation 28] However, here

[0069]

[Equation 29] And also

[0070]

[Equation 30] And

[Equation 31] Is.

To increase the sensitivity using a large number of strain gauges, the following procedure is taken. The average value of the cross sections of a plurality of gauge outputs at the position L _n (n = 1 ... N) is

[0072]

[Equation 32] And Wave propagation takes time, and the position L _n (n = 1 ...
Since the output signals of the strain gauges in N) are not in phase, they can be converted into an output equivalent to the output of the gauge pasted at the representative position L ₁ by using the following procedure 33.

[0073]

[Expression 33] (N = 2 ... N) where

[Equation 34] Are Laplace operator and inverse Laplace operator. Therefore, the distortion of the elastic wave pulse at the representative position is expressed by the following equation.

[0074]

[Equation 35] From this result, it can be understood that it is possible to reduce the influence of noise and measure the minute dynamic strain by calculating the arithmetic mean of the output signals using a plurality of strain gauges.

When the dynamic linearity of the DC type acceleration sensor is measured using the outputs of the plurality of strain gauges as they are, the elastic wave motion due to the propagation of the elastic wave pulse from the representative position to the end face to which the acceleration sensor is attached is measured. It does not take into account the variance and attenuation of. No correction is made considering the dynamic characteristics of the strain gauge. Therefore, a representative example is given when the inner projectile is launched independently, the outer projectile is launched independently, and the inner projectile and the outer projectile are launched simultaneously and independently under the same conditions. Representative strain signal at the position,

[0076]

[Equation 36] Then, since the distance from the representative position of the plurality of strain gauges to the end surface to which the acceleration sensor is attached is LL ₁ , the acceleration a (t) generated on the end surface to which the acceleration sensor is attached in each case is It is expressed by the following equation.

[0077]

[Equation 37] The output signal of the acceleration sensor corresponding to the input acceleration of each equation of Formula 37 is

[0078]

[Equation 38] Then, it is the dynamic linearity of the acceleration sensor that Expression 40 holds within the range where Expression 39 holds.

[0079]

[Formula 39]

[Formula 40]

When the collision of the inner flying object and the outer flying object is not the same, it is possible to measure the dynamic linearity by clarifying the frequency range and the acceleration range in which the equation 41 holds when the time difference is Δt. is there.

[Formula 41]

(3) Next, the gauge output (1 in the axial direction
Individual. ) Is theoretically corrected to obtain the distortion of the elastic wave pulse incident on the end face and the dynamic linearity of the DC type acceleration sensor is measured. In this case, the strain gauge output attached at one location in the axial direction is corrected by elastic wave theory to obtain the elastic wave pulse incident on the end face. However, the frequency response of the gauge is ignored. The strain signal expressed by the equation 13 is assumed to be attached at a position at a distance L ₁ from the collision end face,
The strain signal generated by the collision of the inner flying object only,

[Equation 42] The strain signal generated by the collision of the outer flying object only,

[Equation 43] Distortion signal when the inner flying body and the outer flying body collide at the same time,

[Equation 44] Then, the following formula is established.

[0082]

[Equation 45]

[0083]

[Equation 46] Is the strain of the incident elastic wave pulse on the end face to which the acceleration sensor is attached and the output signal of the strain gauge pasted at the distance L ₁ from the collision end face when the inner and outer projectiles are simultaneously launched. Calculated from equation (3.14)

[0084]

[Equation 47] And the output signal of the acceleration sensor corresponding to each,

[0085]

[Equation 48] Using, the dynamic linearity of the acceleration sensor in [claim 4] is to clarify the frequency range and the acceleration range where the expression 50 is satisfied within the frequency and the acceleration range where the expression 49 is satisfied.

[0086]

[Equation 49]

[Equation 50]

When the collision of the inner flying object and the outer flying object is not simultaneous, it is possible to measure the dynamic linearity by clarifying the frequency range and the acceleration range in which the equation (51) holds when the time difference is Δt. is there.

[0088]

[Equation 51]

(4) Next, the outputs of a plurality of (in the axial direction) strain gauges are theoretically corrected to obtain the strain of the incident elastic wave pulse on the end face, and the dynamic linearity of the DC type acceleration sensor is determined. The case of measuring will be described below. in this case,
As a method of calculating the representative value from the strain gauge outputs pasted in the axial direction, the method shown in Formula 35 of [claim 3] is used, and the strain gauge output signal at the representative position (distance L ₁ from the impact end face) is

When the inner flying object is independently launched,

[Equation 52]

When launching the outer flying object alone,

[Equation 53]

When the inner flying body and the outer flying body are made to collide with the metal rod at the same time,

[Equation 54] Ask about.

[0093]

[Equation 55]

Here,

[Equation 56] The output of the acceleration sensor corresponding to

[0095]

[Equation 57] And In this way, when the output of multiple strain gauges (in the axial direction) is theoretically corrected to determine the strain of the elastic wave pulse incident on the end face, and the dynamic linearity of the DC acceleration sensor is measured. In the above, the dynamic linearity is to clarify the frequency range and the acceleration range in which the equation (5.3) is satisfied within the frequency and the acceleration range in which the equation (58) holds.

[0096]

[Equation 58]

[Equation 59]

When the inner and outer projectiles do not collide at the same time, it is possible to measure the dynamic linearity by clarifying the frequency range and the acceleration range in which the equation 60 is established, where Δt is the time difference. is there.

[0098]

[Equation 60]

(6) Next, the gauge output (1 piece) is corrected by the result of measurement with a laser interferometer to obtain the distortion of the elastic wave pulse incident on the end face, and the dynamic linearity of the DC type acceleration sensor is measured. The case will be described. In this case,
Claim the method of checking the linearity of the input signal by correcting the output of the strain gauge attached at one point in the axial direction, by correcting the result of measurement with a laser interferometer to obtain the strain of the elastic wave pulse incident on the end face. I am trying.

The speed of movement of the rod end surface is measured by an interferometer.

[Equation 61] Is measured and the distortion of the incident elastic wave pulse

[Equation 62] Relationship with

[0101]

[Equation 63] It is represented by. When measuring the dynamics of the DC type accelerometer by correcting the gauge output (1 piece) with the results of measurement with a laser interferometer and obtaining the distortion of the incident elastic wave pulse on the end face, the linearity of the input acceleration is used. To estimate the input acceleration to the accelerometer from the strain gauge output, the frequency response of the gauge is corrected and the interferometer output is analyzed for the dispersion of elastic wave propagation, damping, and the effect of the mass of the accelerometer. Correct the original. The position from the collision end face of the strain gauge attached at one location in the axial direction is L ₁ . Regarding the output signal from the gauge, when the inner flying object is launched alone,

[0102]

[Equation 64] If the outer flying body is launched alone,

[0103]

[Equation 65] When the inner flying body and the outer flying body are simultaneously launched,

[0104]

[Equation 66] And At this time, the correction function on the left side of the equation 67 for converting the output signal of the gauge into the strain of the elastic wave pulse incident on the end face where the acceleration sensor is attached is obtained.

[0105]

[Equation 67] If you decide in this way, the acceleration sensor output when the inner flying object is independently launched

[0106]

[Equation 68] The output of the acceleration sensor when the outer flying object is launched independently,

[0107]

[Equation 69] The acceleration sensor output when the inner flying object and the outer flying object are launched simultaneously,

[0108]

[Equation 70] As for the dynamic linearity when measuring the dynamic linearity of the DC acceleration sensor, the gauge output (1 piece) is corrected by the result of measurement with a laser interferometer to obtain the distortion of the incident elastic wave pulse on the end face. Is to clarify the frequency range and the acceleration range where the formula 72 holds within the frequency and the acceleration range where the formula 71 holds.

[0109]

[Equation 71]

[0110]

[Equation 72]

Further, when the collision of the inner flying object and the outer flying object is not the same, it is possible to measure the dynamic linearity by clarifying the frequency range and the acceleration range satisfying the equation (73) when the time difference is Δt. is there.

[0112]

[Equation 73]

(7) Next, the outputs of a plurality of strain gauges are corrected by the results of measurement with a laser interferometer to obtain the strain of the incident elastic wave pulse on the end face, and the dynamic linearity of the DC type acceleration sensor is determined. The case of measuring will be described. In this case, the outputs of a plurality of strain gauges are corrected by the results of measurement with a laser interferometer to obtain the strain of the elastic wave pulse incident on the end face, and the linearity of the input signal is obtained. Regarding the strain gauge output signal at the representative position obtained by Equation 35,

[0114]

[Equation 74] If the outer flying body is launched alone,

[0115]

[Equation 75] When the inner flying body and the outer flying body are simultaneously launched,

[0116]

[Equation 76] And The output of the acceleration sensor when the inner flying object is launched independently,

[0117]

[Equation 77] The output of the acceleration sensor when the outer flying object is launched independently,

[0118]

[Equation 78] Accelerometer output when inner and outer projectiles are launched simultaneously

[0119]

[Equation 79] As a result, the output of multiple strain gauges is corrected by the results of measurement with a laser interferometer to obtain the strain of the incident elastic wave pulse on the end face, and the dynamic linearity of the DC linear acceleration sensor is measured. The sex is to clarify the frequency range and the acceleration range in which the formula 81 holds within the frequency and the acceleration range in which the formula 80 holds.

[0120]

[Equation 80]

[0121]

[Equation 81] Further, when the collision of the inner flying object and the outer flying object is not the same, the dynamic linearity measurement is to clarify the frequency range and the acceleration range in which the expression (82) is established when the time difference is Δt.

[0122]

[Equation 82]

(8) FIG. 1 shows a rod-shaped body having a diameter of 3c.
An example of a dynamic linearity measuring device of an acceleration sensor using a metal (SUS) round bar having a length of m and a length of 200 cm is shown.
The metal round bar 3 is allowed to fall just before the start of measurement, and after measurement for a short time, it is stopped by being gripped by the round bar brake device 5. During this time, a non-contact type metal round bar guide and a tilting device 4 are provided so that the metal round bar 3 does not come into contact with the round bar brake device 5. With this non-contact type metal round bar guide and tilting device 4, the metal round bar 3
It is also possible to drop in an oblique direction at an inclined angle.

An acceleration sensor 2 to be evaluated is provided on the upper end of the metal round bar 3, and a laser beam 1 from a laser interferometer is irradiated immediately next to the acceleration sensor 2. This laser interferometer can be used as an accurate acceleration sensor because it can measure an accurate distance or its change.
It is important that the accelerometer used here is more accurate than the accelerometer to be calibrated, and there is no reason to limit the accelerometer using the laser interferometer.
However, it is desirable that the acceleration can be detected in a non-contact manner, and there are known a plurality of optical devices that can accurately detect a minute shift, and it is easy to use an acceleration sensor using these. Can understand. Also,
Other than the optical device, an eddy current sensor, an electrostatic micrometer (electrostatic capacitance type displacement meter), or the like can be used.

A strain gauge is attached to the side surface of the metal round bar 3 for detecting elastic waves. The number of strain gauges used here may be plural depending on the detection method of the elastic wave, and the arrangement at this time is preferably symmetrical with respect to the central axis of the metal round bar 3.

As a correction method using this, a single or a plurality of elastic wave detecting strain gauges are provided on the outer periphery of a rod-shaped body on one plane orthogonal to the traveling direction of the elastic wave, and the acceleration for calibration is corrected. There is a method of associating an accelerometer using a laser interferometer with elastic wave data without providing a sensor. This method has an advantage that any acceleration sensor having a common mounting method can be applied, and the correction can be easily performed, but it is not accurate as compared with the following method.

As another correction method, a plurality of elastic wave detection strain gauges and a calibration acceleration sensor are provided on the outer circumference of a rod-shaped body on a plurality of planes orthogonal to the traveling direction of the elastic wave. Then, there is a method of associating an accelerometer using a laser interferometer with elastic wave data. This method is more accurate than the above method, but it is necessary to make correspondence between the accelerometer and the elastic wave data each time the elastic wave medium, the acceleration sensor, or the strain gauge for detecting the elastic wave is replaced.

At the lower end of the metal rod 3, a launch tube 7 (inner diameter = 1.4 cm,
150 cm long and launch tube 10 (inner diameter = 3 cm, length 1)
50 cm) is provided.

By further increasing the number of the firing tubes, more detailed measurement can be performed. Further, in order to generate an elastic wave with no deviation in the metal round bar 3, it is desirable that these launch tubes have a shape symmetrical with respect to the central axis. In these launch tubes, a projectile 8 (made of aluminum, diameter = 1.34 cm, length = 15 cm, mass = 57 g) for colliding, a projectile 9 (made of aluminum, donut-shaped, outer diameter = 2.95 cm, inner diameter = 1.
85 cm, length = 15 cm, mass = 168 g). This projectile is matched to the shape of the launch tube. Further, as the flying objects, elastic waves can be generated not only by the individual objects but also by a composite object composed of a plurality of objects or an object group in which the objects are not combined. Materials of this flying body are used from those having relatively low hardness (for example, bronze) to those having high hardness (for example, ceramics). It is also possible to use a material having a low hardness only at its tip. By adjusting this material, the spectrum of the generated elastic wave can be adjusted.

In the structure shown in FIG. 1, these projectiles are launched by high pressure air from a high pressure air source 14 (pressure = ^{2 to 4} kg / cm ² ) and a high pressure air source 15 (pressure = ² to 4 kg / cm ² ). It is hammered out from the pipes 7 and 10. The timing of the firing is determined by opening / closing the solenoid valves 12 and 13 controlled by the solenoid valve control device 11. The velocity of the projectile thus launched is measured by a well-known optical measuring device including a laser light source 17, a mirror 18, a photodetector 19 and a velocity measuring counter 20. The velocity of this flying object is about 4 m / sec to 40 m / sec, but there is no reason to be limited to this range, and this configuration can be applied even if the velocity is lower or higher. In addition, by measuring the mass of the flying object in advance, the scale of the collision can be predicted, so that the elastic wave to be generated can be predicted.

Further, since the generated elastic wave is attenuated while being repeatedly reflected at both ends of the metal round bar 3, accelerations having different intensities can be applied to the accelerometer by using this. With this method it is also possible to make measurements at several accelerations in one collision.

The position of the launch tube and the position of the acceleration sensor may be reversed, and by using the reversed measurements together,
The offset of the acceleration sensor can be evaluated.

In addition, the launch tube and the flying object corresponding to it are
If it does not have a symmetrical shape with respect to its central axis, the effect of not having a symmetrical shape with respect to the central axis by rotating the projectile or rotating the metal round bar 3 around the movement direction of the projectile It is desirable to check.

[0134]

Since the present invention has the above-mentioned structure,
The effects described below can be achieved.

First, second, seventeenth, eighteenth or first
According to the ninth aspect of the invention, the elastic wave generated by the collision of an object or a group of objects is used for a rod-shaped body that falls vertically or obliquely to cause a rapid acceleration change, and it is possible to compare with an accurate acceleration sensor. Now, it becomes possible to calibrate the acceleration sensor for a wide range of acceleration. Further, in the third aspect of the invention, since the acceleration detecting means using the optical means is used for the accurate acceleration sensor, the accurate acceleration can be measured in a non-contact manner.
Further, in the fourth, fifth, sixth, seventh, eighth, or ninth invention, since the correction is made according to the shape of the elastic wave, the calibration of the accelerometer becomes more accurate.

Further, in the tenth invention, the frequency component of the elastic wave can be changed by changing the material of the colliding object. Further, in the eleventh invention, since the object has symmetry about the movement direction of the object, the elastic wave can be made closer to a plane wave. In the twelfth aspect of the invention, since a plurality of objects collide with each other at a predetermined time interval, the elastic wave can have a predetermined frequency band. Further, in the thirteenth invention, since the correction according to the elastic wave propagation theory is added, more accurate calibration can be performed. In the fourteenth or fifteenth invention,
Since the calibration is performed in the frequency domain, the frequency limit of the calibration can be easily known. Further, in the sixteenth invention, since the overlapping portion of the elastic wave pulses is used, various accelerations can be easily generated.

Further, in the twentieth aspect of the invention, since the reflection and attenuation of the elastic wave pulse are used, various accelerations can be easily generated. In the twenty-first aspect of the invention, since the rod-shaped body and the object that collides with the first end of the rod-shaped body are relatively rotated around the moving direction of the colliding object, the difference in the shape of the object is caused. You can add a correction to

[Brief description of drawings]

FIG. 1 is a schematic view showing a preferred embodiment of the present invention.

[Explanation of symbols]

1 Laser light from laser interferometer 2 Acceleration sensor to be evaluated 3 metal round bar 4 Non-contact metal round bar guide and tilting device 5 Round bar brake device 6 strain gauge 7 launch tube 8, 9 Flying body 10 launch tubes 11 Solenoid valve control device 12, 13 solenoid valve 14, 15 High pressure air source 16 Launch tube tilting device 17 Laser light source 18 mirror 19 Photodetector 20 Speed measurement counter

Claims (21)

[Claims] 1. A rod-shaped body capable of propagating elastic waves by falling vertically or obliquely at a predetermined angle, a means for colliding an object with a first end of the rod-shaped body, and the velocity of the object. For measuring the acceleration, the first acceleration detecting means and the second acceleration detecting means capable of detecting the acceleration of the movement of the second end of the rod-shaped body, the result of the first acceleration detecting means and the first acceleration detecting means. And a means for comparing the result of the acceleration detecting means of No. 2 and an acceleration in the movement of the second end of the rod-shaped body caused by the elastic wave caused by the collision at the first end of the rod-shaped body. A dynamic characteristic measuring device for an acceleration sensor, comprising: a means for detecting the acceleration and a second acceleration detecting means. 2. A rod-shaped body capable of propagating elastic waves by falling vertically or obliquely at a predetermined angle, and means for colliding each object group with a first end of the rod-shaped body. Means for measuring the velocity of the object group, a first acceleration detecting means and a second acceleration detecting means capable of detecting the acceleration of the motion of the second end of the rod-shaped body,
A means for comparing the result of the first acceleration detecting means with the result of the second acceleration detecting means, and a second end of the rod-shaped body caused by an elastic wave caused by a collision at the first end of the rod-shaped body. A dynamic characteristic measuring device for an acceleration sensor, comprising: a first acceleration detecting means and a second acceleration detecting means for detecting the acceleration in the motion of FIG. 3. A rod-shaped body capable of propagating elastic waves by falling vertically or obliquely at a predetermined angle, means for colliding a plurality of objects with a first end of the rod-shaped body, and the above-mentioned object. Means for measuring the velocity, a second acceleration detecting means using the first acceleration detecting means and an optical means capable of detecting the acceleration of the movement of the second end of the rod-shaped body, and the first acceleration detecting means. Means for comparing the result of the acceleration detecting means with the result of the second acceleration detecting means, and the first rod-shaped body.
The acceleration in the motion of the second end of the rod-shaped body caused by the elastic waves caused by the collisions of the plurality of objects that are collided at one end of the first time with the first acceleration detection means and the second acceleration
And a configuration for detecting the acceleration characteristic by the acceleration detecting means of 1. and a dynamic characteristic measuring device for an acceleration sensor. 4. An elastic wave detecting means capable of detecting an elastic wave propagating through the rod-shaped body on a side surface of the rod-shaped body, the elastic wave being caused by collision of the rod-shaped body with a first end thereof. And a configuration in which the result of detecting the acceleration in the movement of the second end of the rod-shaped body caused by the first acceleration detecting means is corrected by the result of detecting the elastic wave by the elastic wave detecting means. The dynamic characteristic measuring device for an acceleration sensor according to any one of claims 1 to 3, further comprising: 5. The dynamic characteristic measurement of the acceleration sensor according to claim 4, wherein the elastic wave detecting means is a means corrected by a result detected by the second acceleration detecting means. apparatus. 6. The means corrected by the result detected by the second acceleration detecting means is arranged in the traveling direction of the elastic wave without providing the first acceleration detecting means on the rod-shaped body. 6. A means including a correspondence between an elastic wave and an acceleration prepared by using one or a plurality of elastic wave detecting means provided on the outer circumference of a rod-shaped body on one orthogonal plane. An acceleration sensor dynamic characteristic measuring device according to. 7. A means corrected by the result of detection by the second acceleration detecting means, wherein the first acceleration detecting means is provided on the rod-shaped body, and is orthogonal to the traveling direction of the elastic wave. 6. The means for including correspondence between an elastic wave and acceleration prepared by using a plurality of elastic wave detecting means provided on the outer periphery of a rod-shaped body on a plurality of flat surfaces, according to claim 5, Accelerometer dynamic characteristics measurement device. 8. A rod-shaped body capable of propagating elastic waves falling vertically or obliquely at a predetermined angle, and means for colliding an object having momentum with a first end of the rod-shaped body. Means for measuring the velocity of the object, elastic wave detecting means capable of detecting elastic waves propagating in the rod-shaped body on the side surface of the rod-shaped body, and movement of the second end of the rod-shaped body. First acceleration detecting means capable of detecting acceleration, means for comparing the result of the first acceleration detecting means with the result of the elastic wave detecting means, and collision with the first end of the rod-shaped body. A configuration in which the acceleration in the motion of the second end of the rod-shaped body caused by the elastic wave collision is detected by the first acceleration detecting means, and the elastic wave is detected by the elastic wave detecting means. Is equipped with Dynamic characteristic measuring device for sensors. 9. The dynamics of the acceleration sensor according to claim 8, wherein the detection result by the elastic wave detecting means is corrected by a correspondence relationship between the characteristic of the elastic wave and the acceleration which is obtained in advance. Characteristic measuring device. 10. The object that collides with one end of the rod-shaped body has a hardness of a tip end portion of a collision portion lower than a hardness of the other portion, according to any one of claims 1 to 9. Accelerometer dynamic characteristics measurement device. 11. The means for colliding an object with the first end of the rod-shaped body has symmetry about the movement direction of the object as an axis, according to any one of claims 1 to 10. Accelerometer dynamic characteristics measurement device. 12. The means for causing an object to collide with the first end of the rod-shaped body comprises a plurality of means at predetermined time intervals so that the elastic wave generated in the rod-shaped body has a predetermined frequency band. 12. The dynamic characteristic measuring device for an acceleration sensor according to claim 1, wherein the object is made to collide. 13. The means for correcting the result of the elastic wave detecting means is a means according to the elastic wave propagation theory, and the elastic wave incident on the second end from the output signal of the elastic wave detecting means. 10. The dynamic characteristic measuring device for an acceleration sensor according to claim 9, wherein at least a first-order term (Skalak's solution) of the analytical solution is included in obtaining the transient distortion signal of the wave pulse. 14. The method according to claim 1, wherein the comparison between the result of the first acceleration detecting means and the result of the second acceleration detecting means is performed in the frequency domain. Accelerometer dynamic characteristics measurement device. 15. A comparison between the result of the first acceleration detecting means or the result of the second acceleration detecting means and the result of the elastic wave detecting means is performed in a frequency domain. 14. A dynamic characteristic measuring device for an acceleration sensor according to any one of claims 4 to 13. 16. A structure in which a plurality of objects collide with the first one end, a structure in which elastic wave pulses due to the collision of the plurality of objects overlap each other, and the overlapping elastic wave pulses are combined in the first structure. 16. The dynamic characteristic measuring device for an acceleration sensor according to claim 1, further comprising: an acceleration detecting unit and a second acceleration detecting unit. 17. While free-falling the rod-shaped body,
The dynamic characteristic measuring device for an acceleration sensor according to any one of claims 1 to 16, wherein elastic wave is generated and detected. 18. The acceleration sensor according to claim 17, wherein the angle between the direction of the gravitational acceleration and the direction of the detected acceleration has a predetermined value during the generation and detection of the elastic wave. Characteristic measuring device. 19. The dynamic characteristic measuring device for an acceleration sensor according to claim 17, wherein the direction of the gravitational acceleration and the direction of the detected acceleration are parallel to each other. 20. The dynamic characteristic measuring device for an acceleration sensor according to claim 1, wherein elastic waves reflected at both ends of the rod-shaped body are used. 21. An elastic wave is generated and detected while relatively rotating the rod-shaped body and an object colliding with a first end of the rod-shaped body around a moving direction of the colliding object. The dynamic characteristic measuring device for an acceleration sensor according to any one of claims 1 to 16.