JP2897080B2 - Displacement meter adjusting method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Adjustment of a linear displacement meter in the prior art is performed as follows. First, as an example of an adjusted linear displacement meter, an optical displacement meter of a triangulation method is exemplified. An optical displacement meter 10 of a triangulation method has a laser light source 11 and an illumination on an incident optical axis as shown in FIG. The lenses 12 are arranged in rows, and the imaging lens 13 and the optical position sensor 14 are arranged in rows on the reflected optical axis at an appropriate angle with respect to the incident optical axis.
Electrodes 14a and 14b are attached to both ends of the optical position sensor 14, and the electrodes 14a and 14b supply output currents from the electrodes 14a and 14b to adders 17 and subtracters 18 via current-voltage converters 15a and 15b and amplifiers 16a and 16b. Connected to be input.
The adder 17 and the subtractor 18 are connected so that their outputs are input to the divider 19. The divider 19 is connected to the linearizer 20 so that its output is input, and the output terminal of the linearizer 20 is the output terminal of the optical displacement meter 10 via the zero point adjuster 21 and the gain adjuster 22. .

In one means, a known displacement is sequentially applied to a target T, and each of the displacements is measured by an optical displacement meter 10.
, And each output value (for example, a detected voltage by a voltmeter) from the output terminal is read, and is plotted on a graph according to each known displacement amount. Then, by repeating the adjustment of the linearizer 20 and the entry of the output value graph as a result, the linearizer is adjusted so that the relationship between the entered output value and the displacement amount has a linearity.
Make 20 adjustments. Subsequently, the zero point adjustment and the gain adjustment are performed in the same manner by the zero point adjuster 21 and the gain adjuster 22.
The adjustment is made by

[0004] In another means, the target is displaced by 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 to a computer. Then, based on the result, the relationship between the displacement amount and the detection output of the optical displacement meter 10 is displayed, and the linearizer 20 is adjusted so as to have linearity while visually observing the relationship. Subsequently, zero point adjustment and gain adjustment are similarly performed by adjusting the zero point adjuster 21 and the gain adjuster 22.

[0005]

The former means of adjusting the linear displacement meter according to the above-mentioned prior art, that is, adjusting the linearizer, is very time-consuming and troublesome by repeating reading, writing and adjustment for each displacement. Very spent. According to the latter means, although the time is slightly shortened as compared with the former case, it still takes time and the apparatus becomes complicated. Furthermore, the optical displacement meter of the triangulation method itself can detect dynamic displacement such as vibration, but the displacement at the time of adjustment is a low-speed displacement, and adjustment in the case of high-speed displacement such as vibration is impossible. It is impossible to adjust dynamic characteristics such as the frequency response of the displacement meter.

[0006]

According to a method of adjusting a displacement meter of the present invention, a sine wave vibration displacement is applied to a target, the displacement is detected by a displacement meter to be adjusted, and the detected output is input 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. Adjusting the linearity of the displacement meter, adjusting the gain adjuster of the displacement meter to be adjusted to adjust the magnitude of the power spectrum of the excitation frequency fundamental wave in the power spectrum, and adjusting the gain of the displacement meter and the power at the zero vibration point Displacement meter that adjusts the offset adjuster of the adjusted displacement meter so that the spectrum approaches zero or a desired value It includes offset adjustment method.

An adjusting device for performing the adjusting method includes:
A target supported to be displaceable by vibration, a vibration driving device for applying sine wave vibration to the target, and an FFT spectrum analyzer connected to a detection output terminal of the adjusted linear displacement meter for detecting sine wave vibration displacement of the target. In addition, a reference displacement meter for detecting a sine wave vibration displacement of the target is provided if necessary, and its detection output terminal is also connected to the FFT spectrum analyzer.

[0008]

The displacement sensor to be adjusted is opposed to the target, and the detection output is input to the FFT spectrum analyzer. Then, the target is oscillated by a vibration drive device. F
When the display screen of the FT spectrum analyzer is set to the mode of the power spectrum display, the display of the input from the adjusted displacement meter to the FFT spectrum analyzer 6 is as follows.
The power spectrum of the excitation frequency fundamental wave and the power spectrum of the harmonic wave appear.

In the adjustment of the linearity of the displacement meter to be adjusted, a linearity error of the displacement meter to be adjusted appears as a harmonic distortion as a power spectrum of a harmonic. Therefore, the linearizer of the displacement meter to be adjusted is adjusted so that the power spectrum of the harmonic 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 displacement amount and the output voltage becomes a predetermined ratio. Adjust the gain adjuster of the adjustment displacement meter.
The offset (zero point) adjustment of the adjusted displacement meter is performed by 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]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A displacement meter adjusting apparatus for implementing a displacement meter adjusting method according to an embodiment of the present invention will be described with reference to the drawings. There are various types of linear displacement meters that can be adjusted according to the present invention, such as a triangulation optical displacement meter and a differential transformer displacement meter. In the embodiment, the triangulation optical displacement meter is used. An example will be described. In the displacement meter adjusting device shown in FIG.
A voice coil type actuator composed of a movable coil 1b and a movable coil 1b is provided, and an irregular reflection surface plate 2, for example, a white ceramic plate is provided on one end surface of the movable coil 1b. A reference displacement sensor 3, for example, a capacitance type displacement sensor, which is higher in accuracy than the displacement meter to be adjusted, is provided facing the other end surface which is a vibration surface as required. Moving coil 1b of vibrator 1
Is connected so that the output of the drive amplifier 5 connected to the sine wave oscillator 4 having a small frequency variable distortion is input, and the FFT spectrum analyzer 6 to which the output of the adjustable displacement meter is input is provided. Have been. The reference displacement sensor 3 is connected to the FFT spectrum analyzer 6 via a capacitance converter 7 so as to input its output.

A feedback circuit for the vibrator 1 is provided as needed to further improve the accuracy. That is, the converter 7 is connected so as to feed back its output to the subtractor 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 7 kHz.
0 dB or more, and preferably two power spectra can be read.

A method of adjusting a displacement meter according to an embodiment of the present invention will be described together with the operation and operation of the above-described device for adjusting a displacement meter. There are various types of linear displacement meters that can be adjusted according to the present invention, such as an optical displacement meter of a triangulation method and a differential transformer. In the embodiment, an optical displacement meter of a triangulation method is exemplified. explain.

First, the optical displacement meter 10 of the triangulation method, which is the displacement meter to be adjusted, is as described above. Therefore, in the adjustment of the optical displacement meter 10, the optical displacement meter 10 projects the laser light from the laser light source 11 onto the irregular reflection surface plate 2 via the illumination lens 12, and the reflected light passes through the imaging lens 13. The light is positioned opposite the diffuse reflection surface plate 2 so as to be 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 the irregular reflection face plate 2 vibrates based on the exciting oscillation current supplied from the drive amplifier 5 to the movable coil 1b. The amplitude of the vibration is set to be as large as possible within the measurement range of the optical displacement meter 10, and a frequency of about 10 to 100 Hz is appropriate, but is selected according to the response of the optical displacement meter 10.

The vibration of the movable coil 1b is converted into the vibration displacement of the irregular reflection face plate 2 and the end face of the movable coil 1b by an optical displacement meter.
It is detected by the ten optical position sensors 14 and the reference displacement sensor 3 of the displacement meter adjusting device. The output from the output terminal of the optical displacement meter 10 based on the detection of the optical position sensor 14 of the optical displacement meter 10 is input to the FFT spectrum analyzer 6.

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

When the display screen of the FFT spectrum analyzer 6 is set to a power spectrum display mode,
The 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) is the power spectrum of the excitation frequency fundamental wave from the sine wave oscillator 4, (b),
(C), (d), and (e) are power spectra of the harmonics. Further, the power spectrum of the detection output of the reference displacement sensor 3 which is input to the FFT spectrum analyzer 6 via the converter 7 and which is used in the FFT spectrum analyzer 6 can be used for monitoring.

First, adjustment of the linearity of the optical displacement meter 10 will be described. When the optical displacement meter 10 has ideal linearity and the linearity error is zero, only the power spectrum (a) of the fundamental wave appears, and the power spectrums (b), (c), and (c) of the harmonics. d) and (e) do not appear, but when there is a linearity error in the optical displacement meter 10, harmonic distortion occurs, and the power spectra of the harmonics (b) and (c) as shown in FIG. , (D), (e)... Appear. Then, since the magnitude of the power spectrum of the harmonic, that is, the distortion factor indicates the linearity error of the optical displacement meter 10, the power spectrum of the harmonic (b), (c), (d), (e).
It is only necessary to adjust the linearizer 20 so as to minimize.

Specifically, the height of the power spectrum of the fundamental wave is represented by e1, and the heights of the harmonics are represented by e2 and e3 in order of height.
, E4, e5... En and the maximum height of the harmonic is assumed to be emax, the cursor of the FFT spectrum analyzer 6 is operated to read the height e1 of the power spectrum of the fundamental wave, and then to read emax. A power spectrum is searched for, a difference ed between them (ed = e1 -emax) is calculated, and the linearizer 20 of the optical displacement meter 10 is adjusted so that ed is maximized.

Next, gain adjustment and offset (zero point) adjustment of the optical displacement meter 10 will be described. Optical displacement meter
In the step 10, after the adjustment of the linearity, the gain needs to be adjusted so that the relationship between the displacement amount and the output voltage becomes a predetermined ratio.
In principle, the gain adjuster 22 may be adjusted so that the height e1 of the power spectrum of the fundamental wave becomes an appropriate height.

Practically, a method using the detection output of the reference displacement sensor 3 is used. As shown in FIG.
The display of the spectrum analyzer 6 is made to simultaneously display two channels of two power spectra. In the example shown,
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. Assuming that 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, Kr × er = Ka × e1 K = Kr / Ka = e1 / er It is sufficient to adjust the gain so that
The gain adjuster 22 is adjusted while calculating the ratio between 1 and er.

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

To adjust the offset (zero point), the display screen of the FFT spectrum analyzer 6 is changed to the one-channel display of only the power spectrum of the detection output of the optical displacement meter 10 and the cursor is set to the DC (0 Hz) position. Since the offset voltage of the detection output of the displacement meter 10 is displayed, the zero point adjuster 21 of the optical displacement meter 10 is adjusted so that this display becomes a predetermined voltage (for example, zero voltage).

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

Although the displacement meter to be adjusted in the above embodiment is the optical displacement meter 10, 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 are available. Can be subject to adjustment. Then, a sine wave vibration displacement may be given to the target corresponding to each displacement sensor, and the target may be detected and adjusted as described above. or,
In the case of a digital output type sensor, its output is D / A
The signal is converted into a spectrum analog voltage by a converter and then input to the FFT spectrum analyzer 6. In the case of a pulse output type sensor, the output is input to a counter,
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]

The adjustment of the displacement meter, that is, the linearity adjustment, the gain adjustment, and the offset (zero point) adjustment can be continuously performed in a short time under the same display of the FFT spectrum analyzer, and the number of operations can be simplified. The adjustment time is reduced to 1/10 as compared with the case of the above technique. Furthermore, adjustment can be performed even for high-speed displacement such as vibration, and dynamic characteristics such as frequency response of the displacement meter can be adjusted.

[Brief description of the drawings]

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

FIG. 2 is a power spectrum of an FFT spectrum analyzer of the displacement meter adjusting device according to the embodiment of the present invention.

FIG. 3 is a power spectrum of an FFT spectrum analyzer of the displacement meter adjusting device according to the embodiment of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exciter 1a Magnet 1b Moving coil 2 Diffuse reflection surface 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 Connection 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 adjuster 22 Gain adjuster

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01C 3/00 -3/32 G01B 11/00-11/30 102

Claims (6)

(57) [Claims] A sine wave vibration displacement is applied to a target, the displacement is detected by a displacement meter to be adjusted, and the detected output is F
A displacement meter adjusting method for inputting to an FT spectrum analyzer and adjusting characteristics of the displacement meter based on a power spectrum obtained by the FFT spectrum analyzer. 2. A sine wave vibration displacement is applied to a target, the displacement is detected by an adjustable displacement meter, and the detected output is
A linearity adjustment method for a displacement meter that inputs to an FT spectrum analyzer and adjusts a linearizer of the displacement meter to be adjusted so as to minimize harmonic components other than the power spectrum of the excitation frequency fundamental wave in the spectrum obtained by the FFT spectrum analyzer. . 3. A sine wave vibration displacement is applied to a target, the displacement is detected by an adjustable displacement meter, and the detected output is F
A method for adjusting the gain of a displacement meter, which is input to an FT spectrum analyzer and adjusts a gain adjuster of the displacement meter to be adjusted so as to adjust the magnitude of the power spectrum of the excitation frequency fundamental wave in the power spectrum obtained by the FFT spectrum analyzer. 4. A sine wave vibration displacement is applied to a target, the displacement is detected by an adjusted displacement meter, and the detected output is F
An offset adjustment method for a displacement meter, which is input to an FT spectrum analyzer and adjusts an offset adjuster of a displacement meter to be adjusted so that a power spectrum at a zero oscillation point obtained by the FFT spectrum analyzer approaches zero or a desired value. 5. A target supported so as to be able to be displaced by vibration.
A displacement driving device for applying a sine wave vibration to a target, and a displacement meter adjusting device including an FFT spectrum analyzer connected to a detection output terminal of an adjusted linear displacement meter for detecting a sine wave vibration displacement of the target. 6. A target supported so as to be capable of vibrating displacement,
A vibration drive device that applies sine wave vibration to the target, a reference displacement meter that detects the sine wave vibration displacement of the target, and connected to each detection output terminal of the adjusted linear displacement meter and the reference displacement meter that detects the sine wave vibration displacement of the target Displacement meter adjusting device composed of a FFT spectrum analyzer.