JP2014153294A - Detected position correction method of electromagnetic induction type position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a correction method enabling accuracy of an electromagnetic induction type position detector itself to be improved by correcting an error specific to the position detector.SOLUTION: A first procedure in which an electromagnetic induction type position detector 22 and a master position detector 23 are attached to a moving body 21; a second procedure in which the moving body is positioned such that a detected position of the electromagnetic induction type position detector becomes a 0 position; a third procedure in which a detected position of the master position detector is reset to the 0 position; a fourth procedure in which a detected position error being a difference between the detected position of the electromagnetic induction type position detector and the detected position of the master position detector is calculated by moving the moving body, and the detected position error and the detected position of the electromagnetic induction type position detector are acquired at each fixed interval position; a fifth procedure in which FFT (Fast Fourier Transform) analysis is performed on the acquired data; a sixth procedure in which errors corresponding to natural periods of error variation are extracted from an FFT analysis result and stored in storage means; and the like are implemented, and inverse FFT analysis is performed on the stored data to correct the detected position of the electromagnetic induction type position detector.

Description

  The present invention relates to a detection position correcting method for an electromagnetic induction type position detector which is a linear scale or a rotary scale.

An inductive thin scale that is an electromagnetic induction type position detector is applied to position detection in various machines such as machine tools, automobiles, and robots. Induct thin type scales include linear scales and rotary scales.
The linear scale is installed on a moving body that moves linearly, such as an XY table of a machine tool, and detects a linear position (movement distance) of the moving body.
The rotary scale is installed on a rotating body (rotating body) such as a rotary table of a machine tool, and detects the rotational position (rotating angle) of the moving body (rotating body).

  The linear scale and the rotary scale are based on the same detection principle, and the position is detected by electromagnetic induction of coil patterns arranged so as to face each other in parallel. This detection principle will be described with reference to FIG.

It has an electromagnetic induction type position detector (linear type scale or rotary type scale), a detection unit and a position detection controller.
As shown in FIGS. 8A and 8B, the detection unit 10 of the electromagnetic induction type position detector (linear scale or rotary scale) includes a primary side member (slider or stator) 1 and a secondary side. And a side member (scale or rotor) 2. 8A and 8B, the primary side member 1 and the secondary side member 2 are illustrated linearly for convenience of explanation, but in the case of a rotary scale, the primary side is actually used. The stator as the member 1 and the rotor as the secondary member are both circular.

A primary member (slider or stator) 1 includes a first primary coil (first slider coil for a slider and a first stator coil for a stator) 3 and a second primary coil (a second slider for a slider). A second stator coil 4 in the case of a coil and a stator.
The secondary side member (scale or rotor) 2 has a secondary side coil (scale coil for scale, rotor coil for rotor) 5.
The coils 3, 4 and 5 are formed in a zigzag shape by connecting a plurality of U-shaped sectors (comb pattern), and in the case of the first and second slider coils and scale coils. Is entirely linear, in the case of the first and second stator coils, the whole is arcuate, and in the case of the rotor coil, the whole is annular.

  In the case of a linear scale, the slider is attached to a moving body that moves linearly, such as an XY table of a machine tool, and moves linearly with the moving body, while the scale is fixed to a fixed part in a machine tool or the like. The In the case of a rotary scale, the rotor is attached to a rotating moving body (rotating body) such as a rotary table of a machine tool and rotates together with the moving body (rotating body), while the stator serves as a fixed part in the machine tool or the like. Fixed.

  As shown in FIG. 8A, the primary side member (slider or stator) 1 and the secondary side member (scale or rotor) 2 are composed of first and second primary coils (first and second slider coils). Alternatively, the first and second stator coils (3, 4) and the secondary coil (scale coil or rotor coil) 5 are arranged so as to face each other in parallel while maintaining a predetermined gap g. Yes. Further, as shown in FIGS. 8A and 8B, the first primary coil (first slider coil or first stator coil) 3 and the second primary coil (second slider). Coil or second stator coil) 4 is offset by a quarter pitch.

  In the electromagnetic induction type position detector (linear scale or rotary scale) having such a configuration, the first primary coil (first slider coil or first stator coil) 3 and the second primary coil (second When an exciting current (alternating current) is passed through the slider coil or the second stator coil 4, the primary side member 1 (in the case of the slider) or the secondary side member 2 (in the case of the rotor) moves with the moving body (the slider is As the rotor moves linearly, the first and second primary coils (first and second slider coils or first and second stator coils) 3, 4 and the secondary side As the relative positional relationship with the coil (scale coil or rotor coil) 5 changes, the first and second primary coils (first and second sliders) as shown in FIG. Coil or first and 2 of the stator coil) 3,4 and the secondary coil (electromagnetic coupling degree between the scale coil or rotor coil) 5 periodically changes. For this reason, an induced voltage that periodically changes is generated in the secondary coil (scale coil or rotor coil) 5.

Specifically, in the position detection controller of the electromagnetic induction type position detector (linear type scale or rotary type scale), the first exciting current Ia as expressed by the following formula (1) is supplied to the first primary coil (the first primary coil). 1 and a second stator current coil (second slider coil or second stator coil) as shown in the following equation (2). 4
Ia = −Icos (kα) sin (ωt) (1)
Ib = Isin (kα) sin (ωt) (2)
Where I: Excitation current magnitude
k: 2π / p
p: Coil pitch
ω: Angular frequency of excitation current (alternating current)
t: time
α: Excitation position The coil pitch p is a length (mm) for a linear scale and an angle (degree) for a rotary scale.

As a result of flowing the first exciting current Ia and the second exciting current Ib, the first and second primary coils (first and second slider coils or first and second stator coils) 3, 4 and Due to the electromagnetic induction effect between the secondary coil (scale coil or rotor coil) 5, an induced voltage V as shown in the following equation (3) is generated in the secondary coil (scale coil or rotor coil) 5. .
V = KIsin (k (X−α)) sin (ωt) (3)
Where K: transfer coefficient depending on the gap g and the angular frequency ω of the excitation current
X: Detection position (moving position of the moving body)

Therefore, the peak amplitude Vp obtained by sampling the induced voltage V in the equation (3) is expressed by the following equation (4).
Vp = KIsin (k (X−α)) (4)

Therefore, in the position detection controller, the peak amplitude Vp is sampled from the induced voltage V of the secondary side coil (scale coil or rotor coil) 5, and the excitation position α where the peak amplitude Vp becomes 0 (ie, the excitation where X = α). The value of the position α) is calculated, the excitation position α is output as the detection position X of the moving body, and the first excitation current Ia and the second excitation current Ib are adjusted based on the excitation position α. That is, the position X of the moving body is detected and output by controlling the induced voltage Vp = 0 by causing the excitation position α to follow the position X of the moving body so that X = α. .
Further, as the electromagnetic induction type position detector (linear type scale or rotary type scale), although detailed description is omitted, there is also known one capable of detecting the absolute position as the detection position X.

JP 2007-064771 A

  However, since an actual electromagnetic induction type position detector (linear type scale or rotary type scale) has a manufacturing error and an installation error, the above equation (4) is not satisfied, and the detection position X has an error. In general, an error of the coil pitch period (an error that periodically fluctuates according to the period of the coil pitch p) is prominently displayed as an error included in the detection position X, and is referred to as an interpolation error.

  For example, if the coil pitch p is 2 mm (in the case of a linear scale) or 2 degrees (in the case of a rotary scale), an interpolation error that fluctuates at a cycle of 2 mm or 2 degrees occurs.

  Further, in order to avoid the interpolation error that fluctuates at a cycle of 2 mm or 2 degrees from becoming too large, the first and first primary coils (first and second slider coils or first and second stators). The coil pitch of the coils 3 and 4 may not be 2 mm or 2 degrees but may be a little smaller than this. For example, the size s of one sector of the first and first primary coils (first and second slider coils or first and second stator coils) 3 and 4 is 2/3 mm (in the case of a linear scale) ) Or 15/16 degrees (in the case of a rotary scale).

In this case, not only the interpolation error that fluctuates at a cycle of 2 mm or 2 degrees, but also the coil pitch p of the secondary side coil (scale coil or rotor coil) is 2 mm or 2 degrees. N (N is a positive integer), and an interpolation error (for example, 1 mm that is 1/2 or an interpolation error that varies with a period of 1 degree, 0.5 mm that is 1/4 or 0. Interpolation error that fluctuates at a cycle of 5 degrees) also occurs.
The sector dimensions s of the first and first primary coils (first and second slider coils or first and second stator coils) 3 and 4 are 2/3 mm or 15/16 degrees. As a result, an interpolation error that fluctuates with a period of 2/3 mm or 15/16 degrees also occurs.

Further, it is caused by the distance d between the first primary coil (first slider coil or first stator coil) 3 and the second primary coil (second slider coil or second stator coil) 4. Thus, an error that fluctuates in a cycle of the coil interval d or a cycle of 1 / N thereof also occurs.
For example, assuming that the coil interval d is 1.5 mm (in the case of a linear scale) or 7.5 degrees (in the case of a rotary scale), an error that fluctuates in a cycle of 1.5 mm or 7.5 degrees, or 1 An error that fluctuates with a period of 0.75 mm or 3.75 degrees that is / 2 also occurs.

Even when the electromagnetic induction type position detector (linear type scale or rotary type scale) is attached, even if the same electromagnetic induction type position detector is used, there are various errors.
In contrast, 0.5 mm or 0.5 degrees, 2/3 mm or 15/16 degrees, 1 mm or 1 degree, 2 mm or 2 degrees, 0.75 mm or 3.75 degrees, 1.5 mm or The error that fluctuates with a natural period such as 7.5 degrees is independent of the mounting state and the like, and is an error (natural period error) inherent to the electromagnetic induction type position detector (linear type scale or rotary type scale).
Therefore, if this natural period error can be corrected, the position detection accuracy of the electromagnetic induction type position detector itself can be improved.

  Therefore, the present invention has been made in view of the above circumstances, and can correct an error inherent in the electromagnetic induction type position detector and improve the position detection accuracy of the electromagnetic induction type position detector itself. It is an object of the present invention to provide a detection position correction method for an inductive position detector.

The detection position correction method of the electromagnetic induction type position detector of the first invention that solves the above-mentioned problem is as follows.
A first procedure for attaching an electromagnetic induction type position detector for detecting an absolute position and a master position detector having a position detection accuracy higher than that of the electromagnetic induction type position detector to a moving body;
A second procedure in which the moving body controller moves and positions the moving body so that the detection position of the electromagnetic induction type position detector becomes 0 position;
A third procedure for resetting the detection position of the master position detector to the 0 position;
The moving body is moved by the moving body controller to calculate a detection position error which is a difference between a detection position of the electromagnetic induction type position detector and a detection position of the master position detector. A fourth procedure for acquiring the detection position of the electromagnetic induction type position detector at every fixed interval position;
A fifth procedure for performing FFT analysis on the acquired detection position error and the detection position data of the electromagnetic induction type position detector;
An error corresponding to the natural period of the error variation of the electromagnetic induction type position detector is extracted from the result of the FFT analysis, and the natural period and the error data corresponding to the natural period are stored in storage means. Procedure and
A seventh procedure for reading the natural period and error data corresponding to the natural period from the storage unit;
An eighth procedure for obtaining an error correction amount corresponding to the detection position of the electromagnetic induction position detector by performing inverse FFT analysis on the natural period read from the storage means and error data corresponding to the natural period When,
And a ninth procedure for correcting the detection position of the electromagnetic induction type position detector based on the error correction amount.

Further, the detection position correction method of the electromagnetic induction type position detector of the second invention is:
A first procedure for attaching an electromagnetic induction type position detector for detecting an absolute position to a moving body;
A second procedure in which the moving body controller moves and positions the moving body so that the detection position of the electromagnetic induction type position detector becomes 0 position;
A third procedure for resetting the moving time used for position calculation in the moving body position calculating means to zero;
The moving body controller moves the moving body at a constant speed, and the detection position of the electromagnetic induction type position detector and the constant speed of the moving body and the moving time of the moving body in the moving body position calculating means are obtained. A detection position error, which is a difference from the position of the moving body calculated by multiplication, is calculated, and a detection position error and a detection position of the electromagnetic induction type position detector are obtained at fixed intervals. Procedure and
A fifth procedure for performing FFT analysis on the acquired detection position error and the detection position data of the electromagnetic induction type position detector;
An error corresponding to the natural period of the error variation of the electromagnetic induction type position detector is extracted from the result of the FFT analysis, and the natural period and the error data corresponding to the natural period are stored in storage means. Procedure and
A seventh procedure for reading the natural period and error data corresponding to the natural period from the storage unit;
An eighth procedure for obtaining an error correction amount corresponding to the detection position of the electromagnetic induction position detector by performing inverse FFT analysis on the natural period read from the storage means and error data corresponding to the natural period When,
And a ninth procedure for correcting the detection position of the electromagnetic induction type position detector based on the error correction amount.

According to the detection position correcting method of the electromagnetic induction type position detector of the first invention, since it has the first to ninth steps described above, an error inherent to the electromagnetic induction type position detector is provided. Therefore, the correction does not adversely affect the position detection accuracy of the electromagnetic induction position detector itself, and the position detection accuracy of the electromagnetic induction position detector itself can be improved.
In addition to the coil pitch period error, the 1 / N period error, sector dimension period error, coil interval period error, and 1 / N period error can be corrected.
Further, an error corresponding to the natural period of the error variation of the electromagnetic induction type position detector is extracted from the result of the FFT analysis, and the natural period and the error data corresponding to the natural period are stored in the storage means. The storage capacity of the storage means can be reduced as compared with the case where all of the detected position error and the data of the detection position of the electromagnetic induction type position detector are stored.

Similarly, the detection position correction method of the electromagnetic induction type position detector of the second invention is characterized by having the above-mentioned first to ninth steps, and is therefore unique to the electromagnetic induction type position detector. Therefore, the correction does not adversely affect the position detection accuracy of the electromagnetic induction type position detector itself, and the position detection accuracy of the electromagnetic induction type position detector itself can be improved.
In addition to the coil pitch period error, the 1 / N period error, sector dimension period error, coil interval period error, and 1 / N period error can be corrected.
Further, an error corresponding to the natural period of the error variation of the electromagnetic induction type position detector is extracted from the result of the FFT analysis, and the natural period and the error data corresponding to the natural period are stored in the storage means. The storage capacity of the storage means can be reduced as compared with the case where all of the detected position error and the data of the detection position of the electromagnetic induction type position detector are stored.
Furthermore, since it is not necessary to use a master position detector, the labor and cost of correction work can be reduced.

It is a block diagram regarding the detection position correction method of the electromagnetic induction type position detector which concerns on Example 1 of Embodiment of this invention. It is a block diagram regarding the detection position correction method of the electromagnetic induction type position detector which concerns on Example 1 of Embodiment of this invention. It is a graph which shows the detection position data (relationship between a detection angle and an error) before correction | amendment. It is a graph which shows the result of having performed the FFT analysis of the detection position data (a relationship between a detection angle and an error) before correction. It is a graph which shows the detection position data (relationship between a detection angle and an error) after correction | amendment. It is a graph which shows the result of having carried out FFT analysis of the detection position data (relationship between a detection angle and an error) after correction. It is a block diagram regarding the detection position correction method of the electromagnetic induction type position detector which concerns on Example 2 of Embodiment of this invention. (A) is arranged so that the primary side member (slider or stator) and secondary side member (scale or rotor) of the electromagnetic induction type position detector (linear scale or rotary scale) face each other in parallel. The perspective view which shows the state which carried out, (b) is a figure which shows the said primary side member (slider or stator) and the said secondary side member (scale or rotor) side by side, (c) is the said primary side member (slider or stator) It is a figure which shows the electromagnetic coupling degree with the said secondary side member (scale or rotor).

  Embodiments of the present invention will be described below in detail with reference to the drawings.

<Embodiment 1>
Based on FIGS. 1-6, the detection position correction method of the electromagnetic induction type position detector which concerns on Embodiment 1 of this invention is demonstrated.

  First, the procedure for storing error correction data (the natural period of error variation of the electromagnetic induction type position detector and the error data corresponding to the natural period) in the ROM (storage means) will be described.

  As shown in FIG. 1, in the first procedure, the electromagnetic induction position detector 22 to be corrected and the master position detector 23 are attached to the moving body 21.

More specifically, the moving body 21 is a moving body that moves linearly such as an XY table of a machine tool, or a rotating body (rotating body) that rotates such as a rotary table of a machine tool.
The electromagnetic induction type position detector 22 is a linear type scale or a rotary type scale, and is the same as the conventional electromagnetic induction type position detector explained based on FIG. 8 and detects the absolute position as the detection position X. Is something that can be done.
The electromagnetic induction type position detector (linear type scale or rotary type scale) 22 includes a detection unit 22A and a position detection controller 22B. A detector 22A is attached to the moving body 21. The detection unit 22A is the same as the detection unit 10 described with reference to FIG. 8, and includes a primary side member (slider or stator) and a secondary side member (scale or rotor).
Therefore, when the electromagnetic induction position detector 22 is a linear scale, a slider (movable part) is attached to the moving body 21 that moves linearly. When the electromagnetic induction type position detector 22 is a rotary scale, a rotor (movable part) is attached to the moving body 21 that is a rotating body.

The position detection controller 22B includes a position detection unit 22a, an error calculation unit 22b, a switch unit 22c, a sampling data acquisition unit 22d, an FFT (Fast Fourier Transform) analysis unit 22e, and a natural period error component extraction. The unit 22f and the ROM 22g (storage means) are included.
When the electromagnetic induction position detector 22 is a linear scale, a master position detector 23 that can detect the linear position (movement distance) of the moving body 21 is used. When the electromagnetic induction type position detector 22 is a rotary scale, a master position detector 23 that can detect the rotation position (rotation angle) of the moving body (rotating body) 21 is used.
The master position detector 23 has a position detection accuracy higher than that of the electromagnetic induction position detector 22 (for example, the position detection error is 1/10 or less compared to the electromagnetic induction position detector 22). Use. As such a high-precision master position detector 23, for example, an optical position detector can be used. Note that the movable portion of the master position detector 23 is attached to the moving body 21.

  In the next second procedure, the detection position of the electromagnetic induction type position detector (linear scale or rotary scale) 22 is set to 0 position (origin: 0 mm for the linear scale and 0 degree for the rotary scale). The moving body controller 24 moves and positions the moving body 21.

  More specifically, in the position detection unit 22a of the position detection controller 22B, based on the induced voltage output from the detection unit (scale or rotor) 22A, the absolute position of the moving body 21 (movement distance in the linear scale, rotary scale) Then, the rotation angle) is detected, and this detection position (detection distance or detection angle) is output. Then, the moving body 21 is moved and positioned by issuing a movement command from the moving body controller 24 so that the detection position (detection distance or detection angle) becomes 0 position (0 mm or 0 degree).

  In the next third procedure, the detection position (detection distance or detection angle) of the master position detector 23 is reset to 0 position (0 mm or 0 degree).

  Specifically, in the position detection unit 22a, when the detection position (detection distance or detection angle) obtained by the position detection unit 22a becomes 0 position (0 mm or 0 degree), 0 is reset to the master position detector 23. The signal r1 is output. Then, the master position detector 23 resets the detection position (detection distance or detection angle) in the master position detector 23 to the 0 position (0 mm or 0 degree) based on the 0 reset signal r1.

  In the next fourth procedure, the moving body controller 24 is moved by the moving body controller 24 to detect the detection position (detection distance or detection angle) of the electromagnetic induction type position detector 22 and the detection position (detection distance) of the master position detector 23. Alternatively, a detection position error (detection distance error or detection angle error), which is a difference from the detection angle), is calculated, and the detection position error and the detection position of the electromagnetic induction type position detector 22 are obtained (sampling) at regular intervals. )

More specifically, the moving body controller 24 positions the moving body 21 so that the detection position of the electromagnetic induction type position detector 22 becomes 0 position, and then moves the moving body 21 at a constant speed in order to obtain error data. Move. When the electromagnetic induction type position detector 22 is a linear scale and the moving body 21 moves linearly, a certain length of the electromagnetic induction type position detector 22 (that is, the entire length of the scale), The moving body 21 is moved. When the electromagnetic induction position detector 22 is a rotary scale and the moving body 21 is a rotating body, the moving body 21 is rotated 360 degrees (that is, one rotation of the rotor).
At this time, the error calculation unit 22b detects the detection position (detection distance or detection angle) output from the electromagnetic induction position detector 22 (position detection unit 22a) and the detection position (detection distance) of the master position detector 23. Alternatively, a detection position error (detection distance error or detection angle error) that is a difference from the detection angle) is calculated.
Further, the position detection unit 22a detects the detection position (detection) at every fixed interval position (for example, every 0.1 mm for the linear scale and every 0.1 degree for the rotary scale) at the switch unit 22c and the sampling data acquisition unit 22d. Distance or detection angle).
In the switch unit 22c, the detection position error calculated by the error calculation unit 22b is set to a detection position (detection distance or detection angle) from the position detection unit 22a at regular intervals (every 0.1 mm or every 0.1 degree). Each time it is input, it is output to the sampling data acquisition unit 22d.

The sampling data acquisition unit 22d acquires a detection position error (detection distance error or detection angle error) from the error calculation unit 22b via the switch unit 22c at every fixed interval position (every 0.1 mm or every 0.1 degree). (Sampling), and the detection position (detection distance or detection angle) of the electromagnetic induction type position detector 22 is acquired from the position detection unit 22a at regular intervals (every 0.1 mm or every 0.1 degree) ( Sampling).
The relationship between the detection position (detection distance or detection angle) acquired by the sampling data acquisition unit 22d and the detection position error (detection distance error or detection angle error) is illustrated in FIG. FIG. 3 illustrates the relationship between the detection angle (degree) and the detection angle error (second) when the electromagnetic induction type position detector 22 is a rotary scale, and the detection angle error fluctuates periodically. The situation is shown. Although illustration is omitted, the relationship between the detection distance (mm) and the detection distance error (second) when the electromagnetic induction type position detector 22 is a linear scale is the same as this.

In the next fifth procedure, the FFT analysis unit 22e performs FFT analysis on the detected position error and the detected position data acquired by the sampling data acquiring unit 22d.
The result of this FFT analysis is illustrated in FIG. FIG. 4 illustrates the relationship between the angle (degrees) and the error amplitude (seconds) when the electromagnetic induction type position detector 22 is a rotary scale. Although illustration is omitted, the relationship between the distance (mm) and the error amplitude (mm) when the electromagnetic induction type position detector 22 is a linear scale is the same as this.

  In the next sixth procedure, an error (natural period error) corresponding to the natural period of the error variation of the electromagnetic induction type position detector (linear scale or rotary scale) 22 is extracted from the result of the FFT analysis, The natural period and error data (correction data) corresponding to the natural period are stored in the storage means.

More specifically, the natural period error component extraction unit 22f calculates the electromagnetic induction position detector (linear scale or rotary scale) 22 from the result of the FFT analysis illustrated in FIG. 4 performed by the FFT analysis unit 22e. An error (natural period error) corresponding to the natural period of the error fluctuation is extracted.
Here, the coil pitch p of the secondary coil (scale coil or rotor coil) in the electromagnetic induction type position detector (linear scale or rotary scale) 22 is set to 2 mm or 2 degrees, and the electromagnetic induction type position detector ( The sector dimension s of the primary side coil (first and second slider coils or first and second stator coils) in the linear scale or rotary scale) 22 is 2/3 mm or 15/16 degrees, and the coil interval d is It is assumed that it is set to 1.5 mm or 7.5 degrees.
For this reason, as described above, the natural period of error variation of the electromagnetic induction type position detector (linear type scale or rotary type scale) 22 is 0.5 mm, 0.5 degree, 2/3 mm, 15/16 degree, 1 mm or For example, 1 degree, 2 mm or 2 degrees, 0.75 mm or 3.75 degrees, 1.5 mm or 7.5 degrees.
Therefore, in the natural period error component extraction unit 22f, from the result of the FFT analysis, the natural period of error variation is 0.5 mm or 0.5 degrees, 2/3 mm or 15/16 degrees, 1 mm or 1 degree, 2 mm or 2 degrees, An error (natural period error) corresponding to 0.75 mm or 3.75 degrees, 1.5 mm or 7.5 degrees is extracted.
In the example of the rotary scale shown in FIG. 4, an error Ea corresponding to a natural period of 0.5 degrees, an error Eb corresponding to a natural period of 15/16 degrees, and an error corresponding to a natural period of 1 degree. Ec, an error Ed corresponding to the natural period of 2 degrees, an error Ee corresponding to the natural period of 3.75 degrees, and an error Ef corresponding to the natural period of 7.5 degrees are extracted. Although illustration is omitted, the same applies to the case of a linear scale.
When the coil pitch p is 2 mm or 2 degrees, an error of the natural period such as 1/8 (0.25 mm or 0.25 degree) is also generated, but the error of the natural period of 1/8 or less is small. I ignored it.
The natural period error extracted here is more specifically the magnitude of the amplitude of the sin component,
This is the magnitude of the amplitude of the cos component.

  And the natural period 0.5 mm or 0.5 degrees, 2/3 mm or 15/16 degrees, 1 mm or 1 degree, 2 mm or 2 degrees, 0.75 mm or 3.75 degrees, 1.5 mm or 7.5 degrees The error data (correction data) corresponding to these natural periods is stored in a ROM 22h (slider or scale for a linear scale, a stator or rotor for a rotary scale) 22A ( Memory).

  These correction data may be stored not only in the ROM 22h of the detection unit 22A but also in the ROM 22g (storage means) of the position detection controller 22B. However, when correction data is stored in the ROM 22g of the position detection controller 22B, the position detection controller 22B needs to be replaced when the detection unit 22A is replaced. On the other hand, when correction data is stored in the ROM 22h of the detection unit 22A, only the detection unit 22A needs to be replaced, which is advantageous in terms of cost and workability.

  The procedures of the first procedure to the sixth procedure as described above are performed, for example, before the electromagnetic induction position detector 22 is shipped at the electromagnetic induction position detector manufacturing factory. Then, the electromagnetic induction position detector 22 storing the correction data in the ROM 22h of the detection unit 22A or the ROM 22g of the position detection controller 22B is shipped.

  Next, a procedure until the detection position of the electromagnetic induction type position detector is corrected will be described.

As shown in FIG. 2, when the position of the moving body 31 is detected using the electromagnetic induction position detector 22 that stores correction data in the ROM 22h of the detection unit 22A or the ROM 22g of the position detection controller 22B, the electromagnetic induction position The detector 22 is attached to the moving body 31.
The moving body 31 is a moving body that moves linearly such as an XY table of a machine tool, or a rotating body (rotating body) that rotates such as a rotary table of a machine tool.
The detection unit 22A is attached to the moving body 31. When the electromagnetic induction type position detector 22 is a linear scale, a slider (movable part) is attached to a moving body 31 that moves linearly. When the electromagnetic induction type position detector 22 is a rotary scale, a rotor (movable part) is attached to the moving body 31 that is a rotating body.
In the first embodiment, the moving body 31 and the moving body controller 32 that use the electromagnetic induction type position detector 22 and the moving body 21 and the moving body for obtaining correction data of the electromagnetic induction type position detector 22 are used. Although the controller 24 is different from the controller 24, the controller 24 is not limited to this and may be the same.

  As shown in FIG. 2, the position detection controller 22B also includes a power ON determination unit 22j, a data reading unit 22i, an inverse FFT analysis unit 22k, a correction table 22m, and a correction calculation unit 22n.

  In the seventh procedure, natural periods of error fluctuations and error data (correction data) corresponding to these natural periods are read from the storage means (ROM 22h or ROM 22g).

More specifically, the power ON determination unit 22j performs ON determination of the power (not shown) of the position detection controller 22B.
When the power ON determination unit 22j determines that the power is turned on, the data reading unit 22i receives a natural period of 0.5 mm or 0.5 degree, 2/3 mm from the ROM 22h of the detection unit 22A or the ROM 22g of the position detection controller 22B. 15/16 degrees, 1 mm or 1 degree, 2 mm or 2 degrees, 0.75 mm or 3.75 degrees, 1.5 mm or 7.5 degrees, and error data (correction data) corresponding to these natural periods are read. .

  In the next eighth procedure, electromagnetic induction is performed by performing inverse FFT analysis on the natural periods of error fluctuations read from the storage means (ROM 22h or ROM 22g) and error data (correction data) corresponding to these natural periods. An error correction amount corresponding to the detection position (absolute detection position) of the equation position detector 22 is obtained.

More specifically, in the inverse FFT analysis unit 22k, the natural period read from the ROM 22h of the detection unit 22A or the ROM 22g of the position detection controller 22B in the data reading unit 22i is 0.5 mm or 0.5 degrees, 2/3 mm or 15/16 degrees. 1 mm or 1 degree, 2 mm or 2 degrees, 0.75 mm or 3.75 degrees, 1.5 mm or 7.5 degrees, and the inverse FFT based on the error data (correction data) corresponding to these natural periods Perform analysis.
As a result, the relationship between the detection position (distance or angle) and the detection error (detection distance error or detection angle error) similar to that before performing the FFT analysis in the fifth procedure described above (FIG. 3) is obtained.
Then, in the inverse FFT analysis unit 22k, based on the result of the inverse FFT analysis, 0 position of the electromagnetic induction type position detector (linear type scale or rotary type scale) 22 (0 mm for the linear type scale and 0 degree for the rotary type scale). Calculate the error correction amount based on. That is, an error correction amount (correction amount of detection distance error or correction of detection angle error) corresponding to the absolute detection position (absolute detection distance or absolute detection angle) of the electromagnetic induction type position detector (linear type scale or rotary type scale) 22 (Quantity).
In the correction table 22m, the error correction amount (detection distance error correction amount or detection angle error correction amount) obtained by the inverse FFT analysis unit 22k is stored in association with the detection position (detection distance or detection angle).

  In the next ninth procedure, the detection position of the electromagnetic induction type position detector 22 is corrected based on the error correction amount.

More specifically, when the moving body 31 is stopped or when the moving body controller 32 is moved (linearly moved or rotated) by the moving body controller 32, an electromagnetic induction type position detector (linear scale or rotary) is used. (Shape scale) 22 detects the position (distance or angle) of the moving body 31.
That is, in the position detection unit 22a of the position detection controller 22B, based on the induced voltage output from the detection unit (scale or rotor) 22A, the absolute position of the moving body 31 (movement distance in a linear scale, rotation in a rotary scale) Angle) is detected, and this detection position (detection distance or detection angle) X (m) is output.
In the correction calculation unit 22n, the detection position (detection distance or detection distance) output from the position detection unit 22a from the data of the error correction amount (detection distance error correction amount or detection angle error correction amount) stored in the correction table 22m. An error correction amount (detection distance error correction amount or detection angle error correction amount) E (m) corresponding to (detection angle) X (m) is selected, and based on this error correction amount E (m), the following ( The detected position X (m) is corrected as in equation (11), and the corrected detected position X ′ (m) is output.
X ′ (m) = X (m) + E (m) (11)
FIG. 5 illustrates the error at the corrected detection position (detection angle) X ′ (m), and FIG. 6 illustrates the result of FFT analysis of the error at the corrected detection position (detection angle) X ′ (m). Illustrated. As shown in FIG. 5, the error at the corrected detection position (detection angle) X ′ (m) is much smaller than that before the correction (FIG. 3). There is almost no error at 5 degrees, 15/16 degrees, 1 degree, 2 degrees, 3.75 degrees, and 7.5 degrees.

As described above, according to the detection position correcting method of the electromagnetic induction type position detector according to the first embodiment, since the first to ninth steps are included, the electromagnetic Since the error inherent to the induction type position detector 22 is corrected, the correction does not adversely affect the position detection accuracy of the electromagnetic induction type position detector 22 itself, and the position detection accuracy of the electromagnetic induction type position detector 22 itself. Can be improved.
In addition to the coil pitch period error, the 1 / N period error, sector dimension period error, coil interval period error, and 1 / N period error can be corrected.
Further, an error corresponding to the natural period of the error variation of the electromagnetic induction type position detector 22 is extracted from the result of the FFT analysis, and the natural period and the error data corresponding to the natural period are stored in the storage means (ROM 22h or ROM 22g). Therefore, the storage capacity of the storage means (ROM 22h or ROM 22g) can be reduced as compared with the case where all of the acquired detection position error and the detection position data of the electromagnetic induction position detector are stored.

<Embodiment 2>
Based on FIG. 7, the detection position correction method of the electromagnetic induction type position detector according to the second embodiment of the present invention will be described.
In the first embodiment, the master position detector is used, but in the second embodiment, the master position detector is not used. calculate.

  First, the procedure for storing error correction data (the natural period of error variation of the electromagnetic induction type position detector and the error data corresponding to the natural period) in the ROM (storage means) will be described.

  As shown in FIG. 7, in the first procedure, the electromagnetic induction position detector 42 to be corrected is attached to the moving body 41.

More specifically, the moving body 41 is a moving body that moves linearly such as an XY table of a machine tool, or a moving body (rotating body) that rotates such as a rotary table of a machine tool.
The electromagnetic induction type position detector 42 is a linear type scale or a rotary type scale, and is the same as the conventional electromagnetic induction type position detector explained based on FIG. 8, and detects the absolute position as the detection position X. It is something that can be done.
The electromagnetic induction type position detector (linear type scale or rotary type scale) 42 includes a detection unit 42A and a position detection controller 42B. The detection unit 42A is attached to the moving body 41. The detection unit 42A is the same as the detection unit 10 described with reference to FIG. 8, and includes a primary side member (slider or stator) and a secondary side member (scale or rotor). Therefore, when the electromagnetic induction type position detector 42 is a linear scale, a slider (movable part) is attached to the moving body 41 that moves linearly. When the electromagnetic induction type position detector 42 is a rotary scale, a rotor (movable part) is attached to the moving body 41 that is a rotating body.

  The position detection controller 42B includes a position detection unit 42a, an error calculation unit 42b, a moving body position calculation unit 42c (moving body position calculation means), a switch unit 42d, a sampling data acquisition unit 42e, and an FFT analysis unit 42f. The natural period error component extraction unit 42g and the ROM 42h (storage means) are provided.

  In the next second procedure, the detection position of the electromagnetic induction type position detector (linear scale or rotary scale) 22 is set to 0 position (origin: 0 mm for the linear scale and 0 degree for the rotary scale). The moving body controller 43 moves and positions the moving body 41.

  More specifically, in the position detection unit 42a of the position detection controller 42B, based on the induced voltage output from the detection unit (scale or rotor) 42A, the absolute position of the moving body 41 (movement distance in the linear type scale, rotary scale) Then, the rotation angle) is detected, and this detection position (detection distance or detection angle) is output. Then, the moving body 41 is moved and positioned by issuing a movement command from the moving body controller 43 so that the detection position (detection distance or detection angle) becomes 0 position (0 mm or 0 degree).

  In the next third procedure, the moving time T used for position calculation in the moving object position calculating unit 43c (moving object position calculating means) is reset to zero.

  More specifically, in the position detection unit 42a, when the detection position (detection distance or detection angle) obtained by the position detection unit 42a becomes 0 position (0 mm or 0 degree), 0 is sent to the moving body position calculation unit 43c. A reset signal r2 is output. The moving body position calculating unit 43c resets the moving time T used for calculating the position (distance or angle) of the moving body 41 in the moving body position calculating unit 43c to 0 based on the 0 reset signal r2. That is, the start time of the moving body 41 is reset to zero.

  In the next fourth procedure, the moving body controller 43 moves the moving body 41 at a constant speed S (a constant linear moving speed when the moving body 41 moves linearly, and the moving body 41 is a rotating body. In the case of a constant rotational speed), the detection position (detection distance or detection angle) of the electromagnetic induction type position detector 42, the constant speed S of the mobile body 41 and the mobile body 41 in the mobile body position calculation unit 43c. A detection position error (detection distance error or detection angle error), which is a difference from the position (distance or angle) of the moving body 41 calculated by multiplying the movement time T, is calculated, and this detection position error and the electromagnetic induction type The detection position of the position detector 42 is acquired (sampled) at regular intervals.

More specifically, the moving body controller 43 positions the moving body 41 so that the detection position of the electromagnetic induction type position detector 42 becomes 0 position, and then moves the moving body 41 to a constant speed S in order to obtain error data. Move with. When the electromagnetic induction type position detector 42 is a linear scale and the moving body 41 moves linearly, the electromagnetic induction type position detector 42 has a certain length (that is, the entire length of the scale), The moving body 41 is moved. When the electromagnetic induction type position detector 42 is a rotary scale and the moving body 41 is a rotating body, the moving body 41 is rotated 360 degrees (that is, one rotation of the rotor).
At this time, the moving body position calculation unit 42c multiplies (S × T) the constant speed S of the moving body 41 and the moving time T (time after resetting to 0) of the moving body 41. The position (distance or angle) of the moving body 41 is calculated.
In the error calculation unit 42b, the detection position (detection distance or detection angle) output from the electromagnetic induction type position detector 42 (position detection unit 42a) and the position of the moving body 41 calculated by the moving body position calculation unit 42c ( A detection position error (detection distance error or detection angle error) that is a difference from the distance or angle is calculated.
Further, the position detection unit 42a detects the detection positions (detection) at regular intervals (for example, every 0.1 mm for the linear scale and every 0.1 degrees for the rotary scale) at the switch unit 42d and the sampling data acquisition unit 42e. Distance or detection angle).
In the switch unit 42d, the detection position error calculated by the error calculation unit 42b is detected from the position detection unit 42a at a predetermined interval position (every 0.1 mm or every 0.1 degree). Every time it is input, it is output to the sampling data acquisition unit 42e.

  In the sampling data acquisition unit 42e, a detection position error (detection distance error or detection angle error) is acquired from the error calculation unit 42b via the switch unit 42d at every fixed interval position (every 0.1 mm or every 0.1 degree). (Sampling), and the detection position (detection distance or detection angle) of the electromagnetic induction type position detector 42 is acquired from the position detection unit 42a at regular intervals (every 0.1 mm or every 0.1 degree) ( Sampling). The relationship between the detection position (detection distance or detection angle) acquired by the sampling data acquisition unit 42e and the detection position error (detection distance error or detection angle error) is the same as in the first embodiment (FIG. 3). is there.

  In the next fifth procedure, the FFT analysis unit 42f performs FFT analysis on the detection position error and the detection position data acquired by the sampling data acquisition unit 42e. The result of this FFT analysis is also the same as in the case of the first embodiment (FIG. 4).

  In the next sixth procedure, an error (natural period error) corresponding to the natural period of the error variation of the electromagnetic induction type position detector (linear scale or rotary scale) 22 is extracted from the result of the FFT analysis, The natural period and error data (correction data) corresponding to the natural period are stored in the storage means.

More specifically, in the natural period error component extraction unit 42g, the natural period of the error fluctuation of the electromagnetic induction type position detector (linear type scale or rotary type scale) 42 is obtained from the result of the FFT analysis performed by the FFT analysis unit 42f. The corresponding error (natural period error) is extracted.
Here, the coil pitch p of the secondary coil (scale coil or rotor coil) in the electromagnetic induction type position detector (linear type scale or rotary type scale) 42 is set to 2 mm or 2 degrees, and the electromagnetic induction type position detector ( The sector dimension s of the primary side coil (first and second slider coils or first and second stator coils) in the linear scale or rotary scale) 22 is 2/3 mm or 15/16 degrees, and the coil interval d is It is assumed that it is set to 1.5 mm or 7.5 degrees.
Therefore, as described above, the natural period of the error variation of the electromagnetic induction type position detector (linear type scale or rotary type scale) 42 is 0.5 mm, 0.5 degree, 2/3 mm, 15/16 degree, 1 mm or For example, 1 degree, 2 mm or 2 degrees, 0.75 mm or 3.75 degrees, 1.5 mm or 7.5 degrees.
Therefore, in the natural period error component extraction unit 42g, from the result of the FFT analysis, the natural period of error variation is 0.5 mm or 0.5 degrees, 2/3 mm or 15/16 degrees, 1 mm or 1 degree, 2 mm or 2 degrees, An error (natural period error) corresponding to 0.75 mm or 3.75 degrees, 1.5 mm or 7.5 degrees is extracted.
When the coil pitch p is 2 mm or 2 degrees, an error of a period such as 1/8 (0.25 mm or 0.25 degree) is also generated, but the error of a period of 1/8 or less is small, so it is ignored here. doing.
The natural period error extracted here is more specifically the magnitude of the amplitude of the sin component,
This is the magnitude of the amplitude of the cos component.

  And the natural period 0.5 mm or 0.5 degrees, 2/3 mm or 15/16 degrees, 1 mm or 1 degree, 2 mm or 2 degrees, 0.75 mm or 3.75 degrees, 1.5 mm or 7.5 degrees Then, error data (correction data) corresponding to these natural periods is stored in a ROM 42i (slider or scale for a linear scale or a stator or rotor for a rotary scale) 42A of an electromagnetic induction position detector 42 (see FIG. Memory).

  These correction data are not limited to the ROM 42i of the detection unit 42A, but may be stored in the ROM 42h (storage means) of the position detection controller 42B. However, as described above, the correction data stored in the ROM 42i of the detection unit 42A is advantageous in terms of cost and workability because only the detection unit 42A needs to be replaced.

  The procedures from the first procedure to the sixth procedure as described above are performed, for example, before the electromagnetic induction position detector 42 is shipped in the electromagnetic induction position detector manufacturing factory. Then, the electromagnetic induction position detector 42 storing the correction data in the ROM 42i of the detection unit 42A or the ROM 42h of the position detection controller 42B is shipped.

Next, a procedure until the detection position X (m) of the electromagnetic induction type position detector 42 is corrected will be performed. This procedure is based on the seventh procedure to the ninth procedure in the first embodiment. Since it is the same as the procedure, description here is omitted.
In the second embodiment, the moving body and position detection controller using the electromagnetic induction position detector 42 and the moving body 41 and moving body controller 43 for obtaining correction data of the electromagnetic induction position detector 42 are used. However, the present invention is not limited to this, and they may be the same.

As described above, according to the detection position correction method of the electromagnetic induction type position detector according to the second embodiment, the first procedure to the ninth procedure (the seventh procedure to the ninth procedure are described above). Therefore, in order to correct an error inherent in the electromagnetic induction position detector 42, the position detection accuracy of the electromagnetic induction position detector 42 itself is corrected. The position detection accuracy of the electromagnetic induction type position detector 42 itself can be improved.
In addition to the coil pitch period error, the 1 / N period error, sector dimension period error, coil interval period error, and 1 / N period error can be corrected.
Further, an error corresponding to the natural period of the error variation of the electromagnetic induction position detector 42 is extracted from the result of the FFT analysis, and the natural period and the error data corresponding to the natural period are stored in the storage means (ROM 42i or ROM 42h). Therefore, the storage capacity of the storage means (ROM 42i or ROM 42h) can be reduced as compared with the case where all of the acquired detection position error and the detection position data of the electromagnetic induction position detector are stored.
Furthermore, since it is not necessary to use a master position detector, the labor and cost of correction work can be reduced.

  The present invention relates to a detection position correction method for an electromagnetic induction type position detector, and is intended to improve the position detection accuracy of the electromagnetic induction type position detector itself regardless of the mounting state of the electromagnetic induction type position detector. It is useful to apply.

DESCRIPTION OF SYMBOLS 21 Mobile body 22 Electromagnetic induction type position detector 22A Detection part 22B Position detection controller 22a Position detection part 22b Error calculation part 22c Switch part 22d Sampling data acquisition part 22e FFT analysis part 22f Natural period error component extraction part 22g, 22h ROM
22i Data reading unit 22j Power ON determination unit 22k Inverse FFT analysis unit 22m Correction table 22n Correction calculation unit 23 Master position detector 24 Mobile controller 31 Mobile unit 32 Mobile unit controller 41 Mobile unit 42 Electromagnetic induction type position detector 42A detection unit 42B Position detection controller 42a Position detection unit 42b Error calculation unit 42c Moving body position calculation unit 42d Switch unit 42e Sampling data acquisition unit 42f FFT analysis unit 42g Natural period error component extraction unit 42h, 42i ROM
43 Mobile controller

Claims (2)

A first procedure for attaching an electromagnetic induction type position detector for detecting an absolute position and a master position detector having a position detection accuracy higher than that of the electromagnetic induction type position detector to a moving body;
A second procedure in which the moving body controller moves and positions the moving body so that the detection position of the electromagnetic induction type position detector becomes 0 position;
A third procedure for resetting the detection position of the master position detector to the 0 position;
The moving body is moved by the moving body controller to calculate a detection position error which is a difference between a detection position of the electromagnetic induction type position detector and a detection position of the master position detector. A fourth procedure for acquiring the detection position of the electromagnetic induction type position detector at every fixed interval position;
A fifth procedure for performing FFT analysis on the acquired detection position error and the detection position data of the electromagnetic induction type position detector;
An error corresponding to the natural period of the error variation of the electromagnetic induction type position detector is extracted from the result of the FFT analysis, and the natural period and the error data corresponding to the natural period are stored in storage means. Procedure and
A seventh procedure for reading the natural period and error data corresponding to the natural period from the storage unit;
An eighth procedure for obtaining an error correction amount corresponding to the detection position of the electromagnetic induction position detector by performing inverse FFT analysis on the natural period read from the storage means and error data corresponding to the natural period When,
A detection position correction method for an electromagnetic induction type position detector, comprising: a ninth procedure for correcting the detection position of the electromagnetic induction type position detector based on the error correction amount. A first procedure for attaching an electromagnetic induction type position detector for detecting an absolute position to a moving body;
A second procedure in which the moving body controller moves and positions the moving body so that the detection position of the electromagnetic induction type position detector becomes 0 position;
A third procedure for resetting the moving time used for position calculation in the moving body position calculating means to zero;
The moving body controller moves the moving body at a constant speed, and the detection position of the electromagnetic induction type position detector and the constant speed of the moving body and the moving time of the moving body in the moving body position calculating means are obtained. A detection position error, which is a difference from the position of the moving body calculated by multiplication, is calculated, and a detection position error and a detection position of the electromagnetic induction type position detector are obtained at fixed intervals. Procedure and
A fifth procedure for performing FFT analysis on the acquired detection position error and the detection position data of the electromagnetic induction type position detector;
An error corresponding to the natural period of the error variation of the electromagnetic induction type position detector is extracted from the result of the FFT analysis, and the natural period and the error data corresponding to the natural period are stored in storage means. Procedure and
A seventh procedure for reading the natural period and error data corresponding to the natural period from the storage unit;
An eighth procedure for obtaining an error correction amount corresponding to the detection position of the electromagnetic induction position detector by performing inverse FFT analysis on the natural period read from the storage means and error data corresponding to the natural period When,
A detection position correction method for an electromagnetic induction type position detector, comprising: a ninth procedure for correcting the detection position of the electromagnetic induction type position detector based on the error correction amount.

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