JPH04232806A - Method and device for adjusting displacement gauge thereof - Google Patents

Abstract

PURPOSE:To perform the linearity adjustment, gain adjustment and zero-point adjustment of a displacement gauge simply and continuously in a short time. CONSTITUTION:An adjusting device is constituted of a target supported displaceably by vibration, a vibration driving device applying sine-wave vibration to the target, and an FET spectrum analyzer connected to the detection output terminal of an adjusted linear displacement gauge detecting the sine-wave vibration displacement of the target. For the measuring method, sine-wave vibration displacement is applied to the target, the displacement is measured by the adjusted displacement gauge, the detected output is inputted to the FET spectrum analyzer, and the displacement gauge is adjusted based on the power spectrum obtained by the FET spectrum analyzer.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement meter adjustment method and apparatus.

0002

2. Description of the Related Art Adjustment of a linear displacement meter in the prior art is carried out as follows. First, a triangulation type optical displacement meter is illustrated as an example of a linear displacement meter to be adjusted.The triangulation type optical displacement meter 10 has a laser light source 11 and an illumination light on the incident optical axis as shown in FIG. lens 1
2 are arranged in a row, and an imaging lens 13 and an optical position sensor 14 are arranged in a row on the reflection optical axis at an appropriate angle with respect to the incident optical axis. Electrodes 14a and 14b are provided at both ends of the optical position sensor 14.
are attached, and the electrodes 14a, 14b are connected such that the output currents from each are input to an adder 17 and a subtracter 18 via current-voltage converters 15a, 15b and amplifiers 16a, 16b. The adder 17 and the subtracter 18 have their respective outputs connected to the divider 19
is connected so that it is input to the The divider 19 is connected to a linearizer 20 so that its output is input, and the output end of the linearizer 20 becomes the output end of the optical displacement meter 10 via a zero point adjuster 21 and a gain adjuster 22. .

In one method, while sequentially applying known displacements to the target T, each displacement is measured using an optical displacement meter 1.
0, read each output value (for example, a voltage detected by a voltmeter) from the output terminal, and write it on a graph according to each known displacement amount. Then, by repeating the adjustment of the linearizer 20 and drawing the resulting output value graph, the linearizer 20 is adjusted so that the relationship between the input output value and the displacement amount has linearity. Subsequently, zero point adjustment and gain adjustment are performed by adjusting the zero point adjuster 21 and gain adjuster 22 using the same method.

In another method, the target is displaced by a screw feed driven by a motor, and the feed amount of the motor and the detection output from the output end of the optical displacement meter 10 are A/D converted and input into a computer. and displaying the relationship between the displacement amount and the detection output of the optical displacement meter 10 based on the result,
Using Linearizer 2 to ensure linearity while visually checking the
0 adjustment is performed. Following that, zero point adjuster 2
1. Zero point adjustment and gain adjustment are performed in the same way by adjusting the gain adjuster 22.

[0005]

[Problems to be Solved by the Invention] The former method of adjusting a linear displacement meter, that is, adjusting its linearizer, according to the above-mentioned conventional technique requires a lot of time and labor because of the repetition of reading, writing, and adjustment for each displacement. is very expended. Although the latter method takes less time than the former method, it still takes more time and is more complex in terms of equipment. Furthermore, the triangulation-type optical displacement meter itself can detect dynamic displacements such as vibrations, but the displacements used for adjustment are slow displacements and cannot be adjusted for high-speed displacements such as vibrations. Therefore, it is impossible to adjust dynamic characteristics such as the frequency response of the displacement meter.

[0006]

[Means for Solving the Problems] The displacement meter adjustment method of the present invention applies a sinusoidal vibrational displacement to a target, detects the displacement with an adjusted displacement meter, and inputs the detection output to an FFT spectrum analyzer. The displacement meter is adjusted based on the power spectrum obtained by the FFT spectrum analyzer, and the linearizer of the adjusted displacement meter is adjusted to minimize harmonic components other than the power spectrum of the excitation frequency fundamental wave in the power spectrum. A method for adjusting the linearity of a displacement meter, a method for adjusting the gain of the displacement meter to adjust the gain adjuster of the displacement meter to adjust the magnitude of the power spectrum of the excitation frequency fundamental wave in the power spectrum, and the power at the zero vibration point. The displacement meter offset adjustment method includes adjusting an offset adjuster of the displacement meter to be adjusted so that the spectrum approaches zero or a desired value.

[0007]The adjustment device that performs the adjustment method is
It consists of a target supported so that it can be vibrated, a vibration drive device that applies sinusoidal vibration to the target, and an FFT spectrum analyzer that is connected to the detection output end of an adjusted linear displacement meter that detects the sinusoidal vibration displacement of the target. A reference displacement meter is provided to detect the sinusoidal vibration displacement of the target as required, and its detection output terminal is also connected to the FFT spectrum analyzer.

[0008]

[Operation] The adjusted displacement meter is faced to the target, and its detection output is input to the FFT spectrum analyzer. The target is then vibrated in a sine wave using a vibration drive device. F
When the display screen of the FT spectrum analyzer is set to power spectrum display mode, the input from the adjusted displacement meter to the FFT spectrum analyzer 6 is displayed as follows.
A power spectrum of the excitation frequency fundamental wave and a power spectrum of harmonics appear.

In adjusting the linearity of the displacement meter to be adjusted, the linearity error of the displacement meter to be adjusted appears as harmonic power spectrum as harmonic distortion. Therefore, the linearizer of the adjusted displacement meter is adjusted so that the harmonic power spectrum is minimized. After adjusting the linearity, the gain of the adjusted displacement meter is adjusted so that the height of the power spectrum of the fundamental wave becomes an appropriate height so that the relationship between the amount of displacement and the output voltage becomes a predetermined ratio. Adjust the gain adjuster of the adjustment displacement meter. Offset (zero point) adjustment of the adjusted displacement meter involves adjusting the zero point adjuster of the adjusted displacement meter so that the power spectrum at the zero vibration point becomes a predetermined voltage (for example, zero voltage).

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS A displacement meter adjusting device for carrying out a displacement meter adjusting method according to an embodiment of the present invention will be described with reference to the drawings. There are various linear displacement meters that can be adjusted according to the present invention, such as a triangulation-type optical displacement meter and a differential transformer-type displacement meter. This will be explained with an example. In the displacement meter adjustment device shown in FIG. 1, a magnet 1a is used as an example of the vibrator 1.
A voice coil type actuator consisting of a moving coil 1b and a moving coil 1b is used, and one end surface of the moving coil 1b is provided with a diffusely reflecting face plate 2, for example, a white ceramic plate. If necessary, a reference displacement sensor 3, such as a capacitive displacement sensor, which is more accurate than the adjusted displacement meter, is provided opposite the other end surface which is the vibration surface. Moving coil 1 of exciter 1
b is connected to input the output of the drive amplifier 5 connected to the frequency variable sine wave oscillator 4 with low distortion, and on the other hand, the FFT to which the output of the adjusted displacement meter is input.
A spectrum analyzer 6 is provided. The reference displacement sensor 3 is connected to an FFT spectrum analyzer 6 via a capacitance converter 7 so as to input its output.

Furthermore, a feedback circuit for the vibrator 1 is provided as necessary to improve accuracy. That is, the converter 7 is connected to feed back its output to a subtracter 8 between the sine wave oscillator 3 and the drive amplifier 4.

The FFT spectrum analyzer 6 has a frequency of DC 10 KHz or more and a dynamic range of 70 dB or more, and is preferably capable of reading two power spectra.

A displacement meter adjustment method according to an embodiment of the present invention will be explained together with the operation and function of the displacement meter adjustment method and device described above. There are various types of linear displacement meters that can be adjusted according to the present invention, such as triangulation-type optical displacement meters and differential transformers. explain.

First, the triangulation type optical displacement meter 10, which is the adjusted displacement meter to be adjusted, is as described above. Therefore, in adjusting the optical displacement meter 10, the optical displacement meter 10 projects the laser light from the laser light source 11 onto the diffusely reflecting face plate 2 through the illumination lens 12, and the reflected light is transmitted through the imaging lens 13. The light is placed opposite the diffusely reflecting surface plate 2 so that the light is incident on the optical position sensor 14. The output end of the optical displacement meter 10 is connected to input the output to the FFT spectrum analyzer 6. The sine wave signal from the sine wave oscillator 4 is input to the drive amplifier 5, and from the drive amplifier 5 to the moving coil 1b.
The diffuse reflection face plate 2 vibrates based on the excitation vibration current supplied to the oscillating current. The amplitude of the vibration is as large as possible within the measurement range of the optical displacement meter 10, and the frequency is 10 to 100.
A frequency of about Hz is appropriate, but it is selected depending on the responsiveness of the optical displacement meter 10.

The vibration of the movable coil 1b is caused by the diffuse reflection surface plate 2.
The vibrational displacement of the end face of the moving coil 1b is detected by the optical position sensor 14 of the optical displacement meter 10 and the reference displacement sensor 3 of the displacement meter adjustment device. Optical displacement meter 1
The output from the output end of the optical displacement meter 10 based on the detection by the optical position sensor 14 of 0 is input to the FFT spectrum analyzer 6.

On the other hand, the reference displacement sensor 3 of the displacement meter adjustment device
The detection output is input to the FFT spectrum analyzer 6 via the converter 7, and is also fed back via the converter 7 to the subtracter 8 between the sine wave oscillator 4 and the drive amplifier 5. The input to the FFT spectrum analyzer 6 is visually checked on the display screen, and the feedback signal to the subtracter 8 is controlled so that the vibration of the moving coil 1b accurately responds to the sine wave signal from the sine wave oscillator 4. conduct.

When the display screen of the FFT spectrum analyzer 6 is set to power spectrum display mode,
A display of the input to the FFT spectrum analyzer 6 from the output end of the optical displacement meter 10 is shown, for example, as shown in FIG. In FIG. 2, (a) shows the power spectrum of the excitation frequency fundamental wave from the sine wave oscillator 4, (b) and (c
), (d), and (e) are the power spectra of the harmonics. Further, the F of the detection output of the reference displacement sensor 3 is inputted to the FFT spectrum analyzer 6 via the converter 7.
The power spectrum in the FT spectrum analyzer 6 can be used for monitoring.

First, the linearity adjustment of the optical displacement meter 10 will be explained. When the optical displacement meter 10 has ideal linearity and the linearity error is zero, only the fundamental wave power spectrum (a) appears, and the harmonic power spectra (b), (c), ( d) and (e) do not appear, but
If there is a linearity error in the optical displacement meter 10, harmonic distortion occurs, and as shown in FIG. 2, the harmonic power spectrum (b), (c), (d), (e)... appears. Therefore, since the magnitude of the harmonic power spectrum, that is, the distortion rate, represents the linearity error of the optical displacement meter 10, the harmonic power spectrum (b), (c), (d), (e
)... can be minimized by adjusting the linearizer 20.

Specifically, the height of the power spectrum of the fundamental wave is e1, and the heights of the harmonics are e2, e2,
Let e3 , e4 , e5 . . . en and the maximum height of the harmonics be emax. Then, operate the cursor on the FFT spectrum analyzer 6 to read the height e1 of the power spectrum of the fundamental wave, and then emax Find the power spectrum that is, and calculate the difference ed, (ed
= e1 - emax ) and adjust the linearizer 20 of the optical displacement meter 10 so that ed is maximized.

Next, gain adjustment and offset (zero point) adjustment of the optical displacement meter 10 will be explained. After adjusting the linearity of the optical displacement meter 10, it is necessary to perform gain adjustment so that the relationship between the amount of displacement and the output voltage becomes a predetermined ratio. In principle, this can be done by adjusting the gain adjuster 22 so that the height e1 of the power spectrum of the fundamental wave becomes an appropriate height.

Practically, a method is used in which the detection output of the reference displacement sensor 3 is used. As shown in Figure 3, FFT
The display of the spectrum analyzer 6 is made to simultaneously display two channels of two power spectra. In the illustrated example,
The power spectrum of the detection output of the optical displacement meter 10 is displayed on the upper side, and the power spectrum of the detection output of the reference displacement sensor 3 is displayed on the lower side. If the displacement/detection output sensitivity of the reference displacement sensor 3 is Kr, and the target displacement/detection output sensitivity of the optical displacement meter 10 is Ka, then Kr ×
It is only necessary to adjust the gain so that er = Ka ×e1 K = Kr /Ka = e1 /er, so e
The gain adjuster 22 is adjusted while calculating the ratio between 1 and er.

[0022] When using the calculation function of the FFT spectrum analyzer 6, e1 /er is always displayed, so
The gain adjuster 22 of the optical displacement meter 10 is adjusted so that this value becomes a predetermined value.

Offset (zero point) adjustment is performed by changing the display screen of the FFT spectrum analyzer 6 to the optical displacement meter 10.
If you display only one channel of the power spectrum of the detection output of The zero point adjuster 21 of the optical displacement meter 10 is adjusted so that the voltage becomes

[0024] If a computer is connected to the outside of the displacement meter adjustment device and a computer-controlled gain adjuster/zero point adjuster adjustment actuator is provided, the gain adjustment/offset (zero point) adjustment described above can be automated.

The displacement meter to be adjusted in the above embodiment is an optical displacement meter 10, but linear displacement meters of various displacement sensors such as an eddy current type non-contact displacement sensor and a contact type differential transformer type displacement sensor can be used. May be subject to adjustment. Then, a sinusoidal vibration displacement is applied to the target corresponding to each displacement sensor, and the displacement is detected and adjusted as described above. In addition, in the case of a digital output type sensor, the output is D/
The spectrum is converted into an analog voltage by an A converter and then input to the FFT spectrum analyzer 6. In the case of a pulse output type sensor, its output is input to a counter, and the data is converted into a spectrum analog voltage by a D/A converter in the same manner as described above, and then input to the FFT spectrum analyzer 6.

[0026]

[Effect of the invention] Adjustment of the displacement meter, that is, linearity adjustment, gain adjustment, and offset (zero point) adjustment, can be performed continuously in a short time under the same display on the FFT spectrum analyzer. The adjustment time is reduced to 1/10 compared to the case using the above technique. Further, it is also possible to adjust high-speed displacement such as vibration, and it is also possible to adjust dynamic characteristics such as frequency response of the displacement meter.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a displacement meter adjustment device in an embodiment of the present invention.

FIG. 2 is a power spectrum of the FFT spectrum analyzer of the displacement meter adjustment device in the embodiment of the present invention.

FIG. 3 is a power spectrum of the FFT spectrum analyzer of the displacement meter adjustment device in the embodiment of the present invention.

FIG. 4 is a configuration diagram of a triangulation type optical displacement meter to which a displacement meter adjustment device according to an embodiment of the present invention is applied.

[Explanation of symbols]

1 Vibrator 1a Magnet 1b Moving coil 2 Diffuse reflection face plate 3 Reference displacement sensor 4 Sine wave oscillator 5 Drive amplifier 6 FFT spectrum analyzer 7 Capacitance voltage converter 8 Subtractor 10 Optical displacement meter 11 Laser light source 12 Illumination lens 13 Conclusion Image lens 14 Optical position sensor 14a Electrode 14b Electrode 15a Current-voltage converter 15b Current-voltage converter 16a Amplifier 16b Amplifier 17 Adder 18 Subtractor 19 Divider 20 Linearizer 21 Zero point adjuster 22 Gain adjuster

Claims (6)

[Claims] [Claim 1] Applying a sinusoidal vibrational displacement to the target,
A displacement meter adjustment method in which the displacement is detected by a displacement meter to be adjusted, the detected output is input to an FFT spectrum analyzer, and the characteristics of the displacement meter are adjusted based on the power spectrum obtained by the FFT spectrum analyzer. [Claim 2] Applying a sinusoidal vibrational displacement to the target,
The displacement is detected by the adjusted displacement meter, and the detection output is input to the FFT spectrum analyzer. How to adjust the linearity of a displacement meter by adjusting the linearizer of the displacement meter. [Claim 3] Applying a sinusoidal vibrational displacement to the target,
The displacement is detected by the adjusted displacement meter, and the detected output is input to the FFT spectrum analyzer. How to adjust the gain of a displacement meter. [Claim 4] Applying a sinusoidal vibrational displacement to the target,
The displacement is detected by the adjusted displacement meter, the detected output is input to the FFT spectrum analyzer, and the offset adjuster of the adjusted displacement meter is used to make the power spectrum of the zero vibration point obtained by the FFT spectrum analyzer closer to zero or a desired value. How to adjust the displacement meter offset. 5. An FFT spectrum connected to a detection output terminal of a target supported for vibrational displacement, a vibration drive device that applies sinusoidal vibration to the target, and an adjusted linear displacement meter that detects the sinusoidal vibrational displacement of the target. A displacement meter adjustment device consisting of an analyzer. 6. A target supported for vibrational displacement, a vibration drive device that applies sinusoidal vibration to the target, a reference displacement meter that detects the sinusoidal vibrational displacement of the target, and an adjusted target that detects the sinusoidal vibrational displacement of the target. A displacement meter adjustment device consisting of an FFT spectrum analyzer connected to each detection output terminal of a linear displacement meter and a reference displacement meter.