JP6636288B2 - Collective autonomous calibration method of rotation angle sensor and displacement sensor in screw lead measurement and screw lead measuring device - Google Patents

Description

  The present invention relates to a screw lead measuring device, and more particularly to a screw lead measuring device such as a precision feed screw, which has a collective autonomous calibration function of a rotation angle sensor and a displacement sensor.

A conventional screw lead measuring device is described in Non-Patent Document 1, for example.

  On the other hand, Non-Patent Document 2 proposes a method of autonomously calibrating a linear error of a single sensor such as a displacement sensor or an angle sensor without using an extra space or additional equipment.

Akira Yamamoto et al., "Practical use of laser interference screw lead measuring machine", Precision Machinery 41/9 (1975), pp. 919. Kei Kiyono et al., "In-situ Autonomous Calibration of Geometric Sensors", Journal of the Japan Society of Precision Engineering, 63/10 (1997), pp. 1417.

However, for example, in the conventional example described in Non-Patent Document 1 described above, a normal laser interferometer realizes a high resolution of the order of nanometers (nm) by interpolating a fractional period of the wavelength as a basic period. Therefore, there is a problem that mixing of nonlinear components due to interpolation is inevitable. The same applies to the rotation angle detector.

With respect to the above problem, if the displacement and the rotation angle of the slide movement can be measured more precisely, the accumulated pitch deviation and the random walk deviation can be calculated more precisely. Normally, these non-linear components are calibrated using a sensor with higher accuracy (high linearity, high resolution, high reproducibility) to achieve the best measurement result within the range of repeatability. Can be adjusted as follows. Therefore, if calibration can be performed without using a more accurate sensor, cost reduction can be expected.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a screw lead measuring device capable of performing calibration without using a more accurate sensor.

  If the present inventor is configured to apply the principle of autonomous calibration described in Non-Patent Document 2 to the above-mentioned screw lead measuring device, the collective autonomous calibration of the rotation angle sensor and the displacement sensor of the screw lead measuring machine can be performed. It has been found that the function is obtained and the calibration can be performed without using a more accurate sensor.

次に、変位計の検出ヘッドを親ねじに平行に微小変位δだけ移動させ、その状態でもう一度前記リード測定を行うことで、以下の数式（２）を得る工程と、

ここに、

は測定対象の形状を表す関数であり、

はこの測定器の変位計の非線形成分を表す関数であり、

は角度変位計側の非線形成分を表す関数である。また、

はリード測定の結果を表す関数であるが、変位の測定・角度測定の繰り返し性・再現性は十分に高いものとする前提条件は満たされているとする。このとき、導関数の近似となる差分式として、以下の数式（３）（４）を得る工程と、

上記数式（３）（４）より数値積分により変位計側の

を推定により得る工程であり、この時点で、較正をしなければ残った

の分の不確かさを減少する工程と、さらに、変位計と角度計の間で出力を見る方を入れ替えても以上と同様の式が成り立つので、それにより、

の低減を成し遂げる工程と、を含むことを特徴とするねじリード測定装置における回転角度センサ及び変位センサの一括自律校正方法が得られる。 That is, in the present invention, as a precondition, the repeatability and reproducibility of displacement measurement and angle measurement are sufficiently high, and the following method and apparatus according to the present invention can be obtained. According to one aspect of the present invention, first, a lead measurement is performed to examine the relationship between the rotation angle λ and y to obtain the following equation (1):

Then, the detection head displacement gauge is moved by δ in parallel minutely displaced lead screw, by performing the lead measurements again in this state, and obtaining the following formula (2),

here,

Is a function representing the shape of the measurement object ,

Is a function representing the nonlinear component of the displacement meter of this measuring instrument,

Is a function representing the nonlinear component on the angular displacement meter side. Also,

Is a function representing the result of the lead measurement, but it is assumed that the precondition that the repeatability and reproducibility of displacement measurement and angle measurement is sufficiently high is satisfied. At this time, a step of obtaining the following equations (3) and (4) as a difference equation that approximates the derivative:

From the above equations (3) and (4), the displacement meter side is obtained by numerical integration.

Is obtained by estimation, and at this point, it remains without calibration.

The same equation holds true even if the process of reducing the uncertainty is reduced and the method of viewing the output between the displacement meter and the angle meter is switched, so that

And a step of achieving a reduction in the number of steps. A method for collectively autonomous calibration of a rotation angle sensor and a displacement sensor in a screw lead measuring device, comprising the steps of:

の低減を成し遂げる工程を可能とするためにねじリード測定装置側は、ロータリエンコーダの取り付け部分に細工をしネジの押し込み等により、主軸に対して検出ヘッドを僅かにねじることが出来る手段を有していることを特徴とするねじリード測定装置が得られる。 According to another aspect of the present invention, there is provided a screw lead measuring device to which the collective autonomous calibration method of the rotation angle sensor and the displacement sensor can be applied, wherein the detection head of the displacement meter is minutely displaced in parallel with a lead screw. is moved by [delta], by performing the lead measurements again in that state, in order to enable to obtain the formula (2), thread lead measuring apparatus side, the crafted mounting portion of the homodyne interferometric displacement meter Further, there is provided a means that can be slightly moved by pushing in a screw or the like, and even if the way of viewing the output between the displacement meter and the goniometer is switched, the same as in the equations (1), (2), (3), and (4) Since the equation holds,

In order to enable the process of achieving the reduction of the thread, the screw lead measuring device side has a means that can slightly twist the detection head with respect to the main shaft by working the attachment part of the rotary encoder and pushing in the screw etc. The screw lead measuring device is characterized in that:

In the screw lead measuring apparatus, the slightly moving it means a structure which gives a small displacement, is constituted by a structure for pushing and pulling the entire stationary micrometer head, means which can be twisted in the slightly, The rotary encoder may have a two-stage configuration, and may be configured by mounting a device capable of slightly rotating the fixed side of the rotary encoder around the rotation axis and re-clamping.

  By using the method of the present invention, it is possible to provide a function of calibrating a sensor for a lead measuring device of a precision lead screw without using an external sensor.

It is a figure for explaining a screw lead measuring device and a measuring method concerning an embodiment of the present invention, (a) is a top view of the screw lead measuring device, (b) is a side view, (c) Is a perspective view thereof. It is a figure which expands and shows the relationship between a measured screw, a slide, and a filler in the screw lead measuring device concerning the embodiment of the present invention. 5 is a flowchart of correction for a linear displacement meter in the screw lead measuring device according to the embodiment of the present invention. 5 is a flowchart of correction for a rotational displacement meter in the screw lead measuring device according to the embodiment of the present invention. 5 is an example of a mechanism for realizing minute rotation according to the embodiment of the present invention.

First, an outline of the present invention will be described. The present invention is applied to a screw lead measuring device having substantially the same mechanical configuration as the conventional screw lead measuring device described in Non-Patent Document 1 described at the beginning of this specification. As this measuring device, for example, devices as shown in FIGS. 1 (a), 1 (b) and 1 (c) are used. In the present embodiment, a description will be given of lead measurement of a ball screw as a precision feed screw.

FIGS. 1A and 1B are views for explaining a screw lead measuring device and a measuring method thereof according to the present embodiment. FIG. 1A is a plan view of the screw lead measuring device, FIG. (c) is a perspective view thereof. FIG. 2 is an enlarged view showing a relationship between a screw to be measured, a slide, and a filler in the screw lead measuring device shown in FIG.
1 (a), 1 (b), 1 (c) and 2, the screw 101 to be measured is supported by both centers (rotation centers 201, 202) and rotated by a spindle motor. The two fillers 206 and 207 are brought into contact with the screw flank of the screw 101 to be measured. The carriage 204 is fed by a lead screw 205 of the measuring instrument according to a lead substantially equal to the nominal lead of the screw 101 to be measured. The slide 208 can move lightly in the axial direction of the lead screw 205 and in the direction perpendicular thereto.

The three plane mirrors 209, 210 and 211 are mounted on the slide 208. A laser interferometer is constituted by using these three plane mirrors 209, 210 and 211 as moving mirrors (corner cubes). This movable mirror captures a position in a direction parallel to the feed direction of the lead screw 205 of the slide 208 to which the two fillers 206 and 207 are fixed. In FIGS. 1A, 1B, and 1C, a homodyne interferometer displacement meter 221 is used for measurement. In this case, the optical system on the fixed mirror side is incorporated in the head of the homodyne interferometer, and only the optical system on the movable mirror side is indicated by an arrow in FIG. This configuration may be replaced by a linear encoder or the like. The rotation angle of the main shaft can be measured simultaneously with the linear displacement by the rotary encoder 231.

The displacement of the moving mirror with respect to the angle is recorded based on the signal generated by the rotary encoder 231 in accordance with the rotation angle of the main shaft, and the cumulative pitch deviation and random walk deviation can be calculated based on this. As pointed out in Non-Patent Document 1, in a measurement using two feelers, a component having an odd number of cycles such as one cycle per rotation of a screw cannot be measured, and thus a measurement method using one feeler. May also be employed. However, for example, in the above-described conventional example, a laser interferometer normally realizes a high resolution of the order of nanometers (nm) by interpolating a fractional period of the wavelength as a basic period, and therefore, the laser interferometer is caused by the interpolation. There is a problem that the incorporation of non-linear components is inevitable. The same applies to the rotation angle detector.

With respect to the above problem, if the displacement and the rotation angle of the slide movement can be measured more precisely, the accumulated pitch deviation and the random walk deviation can be calculated more precisely. Normally, these non-linear components are calibrated using a sensor with higher accuracy (high linearity, high resolution, high reproducibility) to achieve the best measurement result within the range of repeatability. Can be adjusted as follows. Therefore, if calibration can be performed without using a more accurate sensor, cost reduction can be expected.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a screw lead measuring device capable of performing calibration without using a more accurate sensor.
The present inventor has conducted intensive studies on the above-mentioned screw lead measuring device from various viewpoints. As a result, if the screw lead measuring device is modified so that the calibration method described in Non-Patent Document 2 can be applied, the calibration can be performed without using a more accurate sensor. We found that we could do it. The outline of the method is described below.

しかる後に、変位計の検出ヘッドを親ねじに平行に微小変位δだけ移動させ、その状態でもう一度リード測定を行うと、

が得られる。 First, in the present invention, as a precondition, it is assumed that the repeatability and reproducibility of displacement measurement and angle measurement are sufficiently high.
First, a measurement operation is performed once as usual to examine the relationship between the rotation angle λ and y.

Thereafter, the detection head of the displacement meter is moved by a small displacement δ in parallel with the lead screw, and when lead measurement is performed again in that state,

Is obtained.

は測定対称の形状を表す関数である。また、

はこの測定器の変位計の非線形成分を表す関数であり、

は角度変位計側の非線形成分を表す関数である。
ここで、

はリード測定の結果を表す関数であるが、前提条件は満たされているとする（同じ関数、形状関数とする）。
このとき、導関数の近似となる差分式は以下のようになる。

この式より数値積分により変位計側の

の推定は可能である。
この時点で、較正をしなければ残った

の分の不確かさが減少する。
さらに、変位計と角度計の立場を入れ替えても同様の式が成り立ち、

の低減に繋がる。 In order to make this possible, the apparatus side is designed so that the mounting part of the homodyne interferometer type displacement meter 221 can be slightly moved by pushing a screw or the like. In the case of a structure that gives a small displacement in order to allow such a slight movement, it is preferable to adopt a structure in which, for example, the entire fixed side is pushed and pulled by a micrometer head.
here,

Is a function representing the shape of measurement symmetry. Also,

Is a function representing the nonlinear component of the displacement meter of this measuring instrument,

Is a function representing the nonlinear component on the angular displacement meter side.
here,

Is a function representing the result of the lead measurement, but it is assumed that the precondition is satisfied (the same function and the same shape function).
At this time, the difference expression that approximates the derivative is as follows.

From this equation, the numerical value of the displacement meter

Is possible.
At this point, left without calibration

Uncertainty is reduced.
Furthermore, the same equation holds even if the positions of the displacement meter and the angle meter are switched,

Leads to a reduction in

と

の両方の不確かさ要因を低減し得る。このような方法を用いれば、外部センサによらず、精密送りねじのリード測定器用のセンサの較正を行うことができる。 In order to make this possible, the apparatus side can slightly twist the detection head with respect to the main shaft by working the attachment portion of the rotary encoder 231 and pushing in a screw. In order to enable such a slight twist, it is preferable to provide a rotary encoder having a two-stage configuration, and to mount a device capable of slightly rotating the fixed side of the rotary encoder around the rotation axis and re-clamping. Alternatively, the small turning side may be a linear encoder. Of course, since it is only necessary to move the read head of the rotary encoder minutely, a micrometer head or a simple screw may be used. FIG. 5 shows an example of a mechanism for realizing minute rotation. As shown in the figure, when the center of the cylindrical portion 505 is pushed in with a screw (a screw hole is indicated by a double circle), a slight turning angle is generated between the end faces of the cylindrical portion 505.
As described above, by simultaneously using the rotation angle sensor and the displacement sensor,

When

Can reduce both uncertainty factors. By using such a method, it is possible to calibrate a sensor for a lead measuring device of a precision feed screw without using an external sensor.

According to the above apparatus and method, a collective autonomous calibration function of the rotation angle sensor and the displacement sensor of the screw lead measuring device can be obtained, and by applying the function to the screw lead measuring device, a more accurate sensor can be used. Calibration can be performed.

Here, with reference to FIGS. 3 and 4, a description will be given of a flow of correction for the linear displacement meter and correction for the rotational displacement meter in the screw lead measuring device according to the present embodiment. FIG. 3 is a flowchart of correction for a linear displacement meter in the screw lead measuring device according to the present embodiment. FIG. 4 is a flowchart of the correction for the rotational displacement meter.
For the correction of the linear displacement meter, first, the lead measurement operation is performed once as usual (S301), and the relationship between the rotation angle λ and y is checked from the measurement result to obtain the above-described formula (1) (S302). Subsequently, the detection head of the displacement meter is offset (S303), that is, it is moved by a small displacement δ in parallel with the lead screw, and a second (second) lead measurement is performed in that state (S304). Equation (2) is obtained. Thereafter, the nonlinearity of the linear displacement meter is calculated (S305). The measurement result obtained in S302 is corrected using the obtained nonlinearity of the linear displacement meter (S306).
For the correction of the rotational displacement meter, first, a lead measurement operation is performed once as usual (S401), and the relationship between the rotation angle λ and y is checked from the measurement result to obtain the above-described formula (1) (S402). Subsequently, the detection head of the rotational displacement meter (angle meter) is offset (S403), that is, another (second) lead measurement is performed in that state (S404), and the above-described formula (2) is obtained from the measurement result. . Thereafter, the nonlinearity of the rotational displacement meter is calculated (S405). The measurement result obtained in S402 is corrected by the obtained nonlinearity of the rotational displacement meter (angle meter) (S406).
As described above, correction (calibration) is performed for each of the linear displacement meter and the rotary displacement meter (angle meter), and as a result of both corrections, collective autonomous calibration of the rotary displacement meter (angle meter) and the linear displacement meter becomes possible. The structure for offsetting the detection head of the linear displacement meter and the structure for offsetting the detection head of the rotational displacement meter (angle meter) can be realized with a simple structure such as pushing a screw at a minimum. A screw lead measuring device capable of performing calibration without using a sensor can be provided.

A plurality of measurement operations are required. However, to ensure the reliability of the measurement, it is realistic that the measurement is performed a plurality of times, if not all, without losing practicality.

101 screw to be measured, 201, 202 rotation center, 204 carriage,
205 lead screw (of the measuring instrument), 206, 207 filler, 208 slide,
209, 210, 211 plane mirror, 221 homodyne interferometer displacement meter,
231 Rotary encoder

Claims (3)

First, a lead measurement is performed to check the relationship between the rotation angle λ and y to obtain the following equation (1):

Then, the detection head displacement gauge is moved by δ in parallel minutely displaced lead screw, by performing the lead measurements again in this state, and obtaining the following formula (2),

here,

Is a function representing the shape of the measurement object ,

Is a function representing the nonlinear component of the displacement meter of this measuring instrument,

Is a function representing the nonlinear component on the angular displacement meter side. Also,

Is a function representing the result of the lead measurement, but it is assumed that the precondition that the repeatability and reproducibility of displacement measurement and angle measurement is sufficiently high is satisfied. At this time, a step of obtaining the following equations (3) and (4) as a difference equation that approximates the derivative:

From the above equations (3) and (4), the displacement meter side is obtained by numerical integration.

Is obtained by estimation, and at this point, it remains without calibration.

The same equation holds true even if the process of reducing the uncertainty is reduced and the method of viewing the output between the displacement meter and the angle meter is switched, so that

Rotation angle sensor and collective self-calibration method of the displacement sensor in thread lead measurement, characterized in that and a step to achieve a reduction of. A screw lead measuring device to which the collective autonomous calibration method of the rotation angle sensor and the displacement sensor according to claim 1 can be applied, wherein a detection head of the displacement meter is moved by a small displacement δ in parallel with a lead screw, and in that state, by again performing the lead measurements, in order to enable to obtain the formula (2), thread lead measuring apparatus side, the work to the mounting portion of the homodyne interferometric displacement meter, by pushing or the like of the screw, It has a means that can move slightly, and even if the way of looking at the output between the displacement meter and the goniometer is switched, the same expressions as Expressions (1), (2), (3), and (4) are established.

In order to enable the process of achieving the reduction of the thread, the screw lead measuring device side has a means that can slightly twist the detection head with respect to the main shaft by working the attachment part of the rotary encoder and pushing in the screw etc. A screw lead measuring device. In screw lead measuring apparatus according to claim 2, wherein the slightly moving it means a structure which gives a small displacement, is constituted by a structure for pushing and pulling the entire stationary micrometer head, twisting the slightly The screw lead measuring device is characterized in that the rotary encoder has a two-stage structure, and a device capable of slightly rotating the fixed side of the rotary encoder around the rotation axis and re-clamping is mounted.

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