JP3111017B2 - 3-axis accelerometer calibration jig - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-axis accelerometer having sensitive axes orthogonal to each other and used for calibration of sensitivity.
The present invention relates to an axial accelerometer calibration jig.

[0002]

2. Description of the Related Art A conventional three-axis accelerometer calibrating jig is used when performing sensitivity calibration of an orthogonal three-axis (X, Y, Z) accelerometer, for example, a servo accelerometer using gravity acceleration. A calibration jig for fixing an accelerometer for each sensitive axis in order to match the direction of the sensitive axis with the direction of gravitational acceleration is known. Also, when the sensitivity of a piezoelectric accelerometer is calibrated using a vibration device, a calibration jig that re-fixes the accelerometer for each sensitive axis in order to make the sensitive axis direction coincide with the acceleration direction. It has been known.

That is, in order to perform three-axis sensitivity calibration, first, Z
The accelerometer is fixed to the calibration jig so that the acceleration direction coincides with the sensitive axis of the axis acceleration sensor, and the sensitivity is adjusted so as to have a predetermined sensitivity. Then, the acceleration direction is aligned with the sensitive axis of the X-axis acceleration sensor. Fix the accelerometer to the calibration jig so that the accelerometer matches the sensitivity of the accelerometer, and adjust the accelerometer so that the acceleration direction matches the sensitive axis of the Z-axis acceleration sensor. The sensitivity is adjusted so as to be fixed to a jig so as to have a predetermined sensitivity.

[0004]

In the conventional three-axis accelerometer calibration jig, the accelerometer must be fixed again each time the sensitivity of each axis is adjusted. Was complicated, and it was difficult to quickly perform sensitivity calibration.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a three-axis accelerometer with a single mounting operation to a calibration jig. It is an object of the present invention to provide a three-axis accelerometer calibration jig capable of performing sensitivity calibration.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention is a calibration jig for fixing the three-axis accelerometer when sensitivity calibration of the three-axis accelerometer is performed using gravitational acceleration. A mounting surface having an angle of tan ^-1 (2 ^1/2 ) with respect to a plane orthogonal to the direction of gravitational acceleration, and the mounting surface is provided with an X-direction sensing axis of the three-axis accelerometer. The three-axis accelerometer is mounted so that a gravitational acceleration equal to the Y-direction sensing axis acts.

[0007] According to a second aspect of the present invention, there is provided a three-dimensional system using a vibration device.
A calibration jig for fixing said three-axis accelerometer when performing sensitivity calibration of said axis accelerometer, said mounting jig having an angle of tan ^-1 (2 ^1/2 ) with respect to a plane perpendicular to the acceleration direction. A surface, and the three-axis accelerometer is mounted on the mounting surface such that an acceleration equal to the X-direction sensitive axis and the Y-direction sensitive axis of the three-axis accelerometer acts thereon.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a perspective view of a jig for calibrating a three-axis accelerometer according to the first aspect of the invention, FIG. 2 is an explanatory diagram of a configuration of the three-axis accelerometer, and FIG.
FIG. 4 is a schematic diagram of a three-axis accelerometer calibration device, and FIG. 5 is a perspective view of the three-axis accelerometer calibration jig according to the second embodiment. FIG. 6 is an operation explanatory view of the jig for calibrating the three-axis accelerometer according to the second aspect of the present invention.

As shown in FIG. 1, a three-axis accelerometer calibration jig according to the first aspect of the present invention includes a metal base 1 and a base 1.
The base 1 is provided with an adjusting screw 1b for forming a horizontal plane orthogonal to the direction of gravitational acceleration on the upper surface 1a. Reference numeral 3 denotes a level for confirming that the upper surface 1a of the base 1 is horizontal.

The block 2 is formed of a metal material (for example, aluminum) into a right triangular prism.
a and the angle of each vertex of the right-angled triangle as the bottom surface are 9
About 35.26 ° at 0 ° and tan ⁻¹ (2 ^−1/2 ), tan ⁻¹
(2 ^1/2 ) is about 54.74 °. The reason why the angles of the apex angles are set as described above will be described later.

The block 2 is placed on the upper surface 1a of the base 1 with the side surface of the right triangular prism having the vertical angle of 35.26 ° facing the upper surface 1a of the base 1. Also, 90 °
The three pins 2c for positioning and fixing the three-axis accelerometer 4 are provided on the mounting surface 2b, which is the side surface of the right-angled triangular prism whose apex angle is opposite.
Are vertically projected. Therefore, the mounting surface 2b is about 35.26 ° with respect to the direction of gravitational acceleration, and the upper surface 1a of the base 1
About 54.74 °.

As shown in FIG. 2, the three-axis accelerometer 4 has an X-axis acceleration sensor 5, a Y-axis acceleration sensor 6, and a Z-axis acceleration sensor 7 whose sensing axes are orthogonal to each other, and The servo accelerometer is disposed on the upper surface 8a of the base 8 and covers the upper surface 8a of the base 8 with a cylindrical case 9 and has sensitivity even in gravitational acceleration (DC region). The three-axis accelerometer 4 may be, for example, a strain gauge accelerometer having a sensitivity in a DC region.

The X-axis acceleration sensor 5 and the Y-axis acceleration sensor 6 have their sensitive axes arranged in parallel with the upper surface 8a of the base 8, and the Z-axis acceleration sensor 7 has the sensitive axis
Is arranged perpendicularly to the upper surface 8a of the first member. A mounting hole 8d is formed in the flange portion 8b of the base 8 so as to fit the pin 2c and bring the bottom surface 8c of the base 8 into close contact with the mounting surface 2b of the block 2 so as to be fixed to the block 2.

The three-axis accelerometer 4 is mounted on the mounting surface 2b of the block 2.
When fixed to, the X-axis acceleration sensor 5 and the Y-axis acceleration sensor 6 have their sensing axes parallel to the mounting surface 2b, and the Z-axis acceleration sensor 7 has And become vertical.

The operation of the three-axis accelerometer calibration jig according to the first aspect of the present invention will be described. As shown in FIG. 1, the pin 2c is fitted into the mounting hole 8d, and the three-axis accelerometer 4 is fixed to the block 2. At this time, FIG.
As shown in (a), the angle between the gravitational acceleration G and the mounting surface 2b of the block 2 is defined as θ. Then, the component of the gravitational acceleration G parallel to the mounting surface 2b of the block 2 is G · cos θ,
The vertical component is G · sin θ.

Then, as shown in FIG. 3B, the direction of G · cos θ which is a component of the gravitational acceleration G is formed by the X-direction sensing axis 5a and the Y-direction sensing axis 6a of the three-axis accelerometer 4. The three-axis accelerometer 4 is fixed to the mounting surface 2b of the block 2 so as to coincide with the axis H that bisects the angle (90 °).

Therefore, the mounting surface 2 is attached to the Z-direction sensing shaft 7a.
G · sin θ, which is a component perpendicular to b, acts on the X-direction sensing axis 5a and the Y-direction sensing axis 6a.
os45 ° acts. Here, an angle θ for giving an equivalent acceleration to each of the X, Y, and Z sensing axes 5a, 6a, and 7a.
Ask for.

That is, as shown in FIG.
G, cos θ, cos 45 °, which is a component of the gravitational acceleration G acting on the a and Y direction sensing axes 6 a, and the Z direction sensing axis 7
An angle θ at which G · sin θ, which is a component of the gravitational acceleration G acting on a, becomes equal may be obtained. Therefore, G · cos
From θ · cos 45 ° = G · sin θ,

Θ = tan ⁻¹ (2 ^−1/2 ), which is about 3
5.26 °.

If the angle between the upper surface 1a of the base 1 and the mounting surface 2b of the block 2 is α (90 ° −θ),

Α = tan ⁻¹ (2 ^1/2 ), which is approximately 5
4.74 °.

The above angle θ (about 35.26 °),
The sensitivity of the three-axis accelerometer 4 is calibrated by using the gravitational acceleration G using a three-axis accelerometer calibration jig provided with the block 2 having α (about 54.74 °). Then
The same acceleration component due to the gravitational acceleration G (approximately 57.7% of the gravitational acceleration G) acts on each of the X, Y, and Z axis acceleration sensors 5, 6, and 7.

Therefore, in the three-axis accelerometer calibration device as shown in FIG. 4, the output voltages of the X, Y, and Z axis acceleration sensors 5, 6, and 7 are displayed so as to display the same value (about 565 Gal). If the gains of the amplifier 8 and the display 9 are adjusted, the sensitivity calibration of each of the axis acceleration sensors 5, 6, and 7 can be performed by attaching the three-axis accelerometer 4 to the calibration jig only once.

As shown in FIG. 5, the three-axis accelerometer calibration jig according to the second aspect of the present invention comprises a metal base 11, and a block 12 mounted on the upper surface 11a of the base 11. The base 11 is provided with fixing screws 14 for fixing to the vibration table 13 of the vibration device. A indicates the direction of the vibration by the vibration device and the magnitude of the acceleration.

The block 12 is formed of a metal material (eg, aluminum) into a right-angled triangular prism. The apex angles of the upper surface 12a of the right-angled triangular prism and the right-angled triangle serving as the bottom surface are 90 ° and tan ⁻¹ (2 ^{1), respectively. / 2} ) about 54.74 °, ta
It is about 35.26 ° at n ⁻¹ (2 ^−1/2 ). In addition,
The reason why the angle of each apex angle is set as described above will be described later.

The block 12 is placed on the upper surface 11 a of the base 11, with the side surface of the right triangular prism having a vertical angle of 54.74 ° facing the upper surface 11 a of the base 11. In addition, three pins 12c for positioning and fixing the three-axis accelerometer 14 are vertically protruded from a mounting surface 12b, which is a side surface of a right-angled triangular prism having a vertical angle of 90 ° opposite thereto. Therefore, the mounting surface 12b forms an upper surface 11a of the base 11, that is, a plane of about 35.26 ° with respect to the vibration direction.

Three-axis accelerometer 14 to be subjected to sensitivity calibration
Are servo accelerometers having sensitivity even in the gravitational acceleration (DC area) shown in FIG. 2, and piezoelectric accelerometers having no sensitivity in the gravitational acceleration (DC area).

The operation of the three-axis accelerometer calibration jig according to the second aspect of the present invention will be described. As shown in FIG. 5, the pin 12c is fitted into the mounting hole 18d to fix the three-axis accelerometer 14 to the block 12. At this time,
As shown in FIG. 6A, an angle between the acceleration A and the mounting surface 12b of the block 12 is represented by β. Then, the component of the acceleration A parallel to the mounting surface 12b of the block 12 is A · cos
β, the vertical component is A · sin β.

Then, as shown in FIG. 6B, the direction of A · cos β which is a component of acceleration A is
The angle between the X-direction sensing axis 5a and the Y-direction sensing axis 6a (9)
The three-axis accelerometer 14 is fixed to the mounting surface 12b of the block 12 so as to coincide with the axis H that bisects (0 °).

Therefore, the mounting surface 1 is attached to the Z-direction sensing shaft 7a.
A · sin β, which is a component perpendicular to 2b, acts on the X-direction sensing axis 5a and the Y-direction sensing axis 6a.
cos 45 ° acts. Here, an angle β for giving equivalent acceleration to each of the X, Y, and Z sensing axes 5a, 6a, and 7a is obtained.

That is, as shown in FIG.
The angle β at which A · cos β · cos 45 ° which is a component of the acceleration A acting on the a-direction sensitive axis 6a and A · sin β which is a component of the acceleration A acting on the Z-direction sensitive axis 7a is obtained. I just need. Therefore, A.cosβ.co
From s45 ° = A · sin β,

Β = tan ⁻¹ (2 ^−1/2 ), and about 3
5.26 °.

The three-axis accelerometer 14 can be obtained by using a vibrating device by using a three-axis accelerometer calibration jig provided with the block 12 having the angle β (about 35.26 °) as described above.
Calibrate the sensitivity of. Then, the same acceleration component (approximately 57.7% of the acceleration A) due to the acceleration A acts on each of the X, Y, and Z axis acceleration sensors 5, 6, and 7.

Therefore, with a calibration device as shown in FIG.
If the gains of the amplifier 8 and the display 9 are adjusted so that the output voltages of the Y and Z axis acceleration sensors 5, 6, and 7 display the same value, the axis acceleration sensors 5, 6, and 7 are adjusted. Can be performed by attaching the three-axis accelerometer 14 to the calibration jig only once.

FIG. 5 shows a horizontal vibration device. However, if a calibration jig having a mounting surface having an angle of about 35.26 ° with respect to the acceleration direction is used, the vertical vibration device can be used. A vibration device may be used.

If the vibration direction A of the vibration device shown in FIG. 5 is set so as to be orthogonal to the direction of gravitational acceleration, that is, the mounting surface 12b is tanned with respect to a plane perpendicular to the direction of the vibration acceleration. If an angle of ^-1 (2 ^1/2 ) (about 54.74 °) is formed, sensitivity calibration using the gravitational acceleration G of a servo accelerometer having sensitivity even in the DC region is performed.
The components of the gravitational acceleration G are as follows.
Acts on 6,7.

Assuming that the gravitational acceleration G is 980 Gal, Z
The component of the gravitational acceleration G acting on the axial acceleration sensor 7 is 9
80 × sin (54.74 °) = 800, and the component of the gravitational acceleration G acting on the X-axis acceleration sensor 5 and the Y-axis acceleration sensor 6 is 980 × cos (54.74 °) × co
s (45 °) = 400. That is, a sharp gravitational acceleration G component of 400 Gal acts on the X-axis acceleration sensor 5 and the Y-axis acceleration sensor 6 and 800 Gal acts on the Z-axis acceleration sensor 7.

Therefore, the sensitivity calibration using the gravitational acceleration G and the acceleration A of the vibrating device can be performed by attaching the triaxial accelerometer 14 to the calibration jig only once.

Whether the sensitivity of the three-axis accelerometer 4 is calibrated using the gravitational acceleration G or the sensitivity of the three-axis accelerometer 14 is calibrated using the vibrating device, the angle with respect to the acceleration direction is constant. , Tan ^-1 (2 ^-1/2 ) (approximately 35.26 °), the X-, Y-, and Z-axis acceleration sensors 5 are fixed by fixing the three-axis accelerometers 4 and 14 as described above. , 6, 7 (approximately 57.7 of the gravitational acceleration G or the acceleration A).
%) Acts.

Further, even when the sensitivity of the three-axis accelerometer 4 is calibrated using the gravitational acceleration G, the three-axis accelerometer 4 can be calibrated using the vibration device.
Even when the sensitivity calibration of the axis accelerometer 14 is performed, the blocks 2 and 12 can be formed in the same shape.
It can be shared by placing or fixing it on the upper surface 1a of the base 1 or the vibration table 13.

That is, blocks 2 and 12 which are right triangles
When the block 2 is mounted on the upper surface 1a of the base 1 by contacting the side surfaces of the upper surfaces 2a and 12a of which the apex angle of 35.26 ° faces the upper surface 1a of the base 1, The sensitivity of the axis accelerometer 4 can be calibrated. On the other hand, if the side surface having the apex angle of 54.74 ° is in contact with the vibration table 13 and the block 2 is fixed to the vibration table 13, the sensitivity of the three-axis accelerometer 14 using the vibration device can be calibrated. .

When the sensitivity of the three-axis accelerometer 4 is calibrated using the three-axis accelerometer calibration jig shown in FIG. 1, the gravitational acceleration is fixed by fixing the calibration jig to the vertical vibration device. By vibrating in the direction, the sensitivity calibration using the gravitational acceleration G and the acceleration of the vibrating device can be performed by performing the work of attaching the triaxial accelerometer 4 to the calibration jig only once.

X, Y, Z axis acceleration sensors 5,
In the case of the three-axis accelerometers 4 and 14 in which the sensitivity calibration of 6, 7 is already performed for each axis alone, the sensitivity calibration is performed by using the three-axis accelerometer calibration jig according to the present invention. It is possible to know the assembly accuracy of each of the axis acceleration sensors 5, 6, 7.

If the acceleration sensors having polarities in the X, Y, and Z axes are used, the mounting state of the acceleration sensor can be checked from the phase relationship between the output signals of the acceleration sensors.

[0045]

As described above, according to the present invention, 3
If the axis accelerometer is fixed to the mounting surface of the calibration jig, the sensitivity calibration of the three-axis accelerometer can be performed simultaneously for three axes.
Installation of the three-axis accelerometer to the calibration jig only needs to be performed once.
The sensitivity calibration of the three-axis accelerometer can be speeded up.

[Brief description of the drawings]

FIG. 1 is a perspective view of a jig for calibrating a three-axis accelerometer according to the invention of claim 1;

FIG. 2 is a diagram illustrating the configuration of a three-axis accelerometer, (a) is a layout diagram of an acceleration sensor, and (b) is a side view of the three-axis accelerometer.

FIGS. 3A and 3B are explanatory diagrams of the operation of the jig for calibrating a three-axis accelerometer according to the first embodiment of the present invention, and FIG. 3A is a diagram illustrating a gravitational acceleration component perpendicular and parallel to a mounting surface of the three-axis accelerometer; Fig. 3 is a diagram showing a decomposition state of the gravitational acceleration component parallel to the mounting surface of the three-axis accelerometer into X and Y axes.

FIG. 4 is a schematic block diagram of a calibration device for a three-axis accelerometer.

FIG. 5 is a perspective view of a jig for calibrating a three-axis accelerometer according to the invention of claim 2;

FIGS. 6A and 6B are explanatory diagrams of the operation of the jig for calibrating a three-axis accelerometer according to the second embodiment of the present invention; FIG. 6A is a diagram showing acceleration components perpendicular and parallel to a mounting surface of the three-axis accelerometer; The figure which shows the decomposition | disassembly state of the acceleration component parallel to the mounting surface of a three-axis accelerometer into X and Y axes.

[Explanation of symbols]

1, 11: base, 1a, 11a: upper surface of base, 2, 12
... Block, 2a, 12a ... Top surface of block, 2b, 1
2b mounting surface, 3 level, 4, 14 3-axis accelerometer,
5: X-axis acceleration sensor, 5a: X-direction sensing axis, 6: Y-axis acceleration sensor, 6a: Y-direction sensing axis, 7: Z-axis acceleration sensor, 7a: Z-direction sensing axis, 13: Exciting table , 14 ... fixing screws.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01P 21/00 G01P 15/18

Claims (2)

(57) [Claims] 1. A calibration jig for fixing a three-axis accelerometer when sensitivity of the three-axis accelerometer is calibrated using gravitational acceleration, wherein the calibration jig has an angle with respect to a plane orthogonal to a gravitational acceleration direction. Is provided with a mounting surface which is tan ^-1 (2 ^1/2 ), and the three-axis accelerometer is provided with a gravitational acceleration equal to the X-direction sensitive axis and the Y-direction sensitive axis on the three-axis accelerometer. A three-axis accelerometer calibration jig to which an accelerometer is attached. 2. A calibration jig for fixing the three-axis accelerometer when performing sensitivity calibration of the three-axis accelerometer using a vibrating device, wherein the calibration jig has an angle with respect to a plane orthogonal to the acceleration direction. Is a tan ^-1 (2 ^1/2 ) mounting surface, and the three-axis acceleration is set so that acceleration equal to the X-direction sensitive axis and the Y-direction sensitive axis of the three-axis accelerometer acts on the mounting surface. A jig for calibrating a three-axis accelerometer, wherein a jig is attached.