JP2003262518A - Self-calibrating angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angle detector that can detect angles with high accuracy over many years by self-calibrating angle data in a state where the detector is attached to a machine or device, such as the rotating machine, etc. <P>SOLUTION: This self-calibrating angle detector which detects the rotational angle of a disk by means of a detection head finds an N-nary error component by using angle data detected by means of an N-nary error component detecting head installed in a position which is separated from the 0°-position in which the detection head is installed by (360/2N)° and self-calibrates the angle data by subtracting the N-nary error component from the angle data detected by means of the N-nary error component detecting head. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angle detector, and more particularly, by providing a self-calibration function, it is possible to maintain highly accurate angle detection performance for many years without removing it from a mechanical device such as a rotating machine. For new improvements for.

[0002]

2. Description of the Related Art Conventionally, in a known angle detector, it is periodically removed from a mechanical device such as a rotating machine, sent to a manufacturer, an accuracy error is measured by a calibration device, and readjustment is performed if necessary. Was there.

[0003]

Since the conventional device is constructed as described above, the following problems exist. That is, since it is periodically removed and readjustment is required, it is not possible to maintain the highly accurate angle detection performance for many years without removing it.

The present invention has been made to solve the above problems, and in particular, it is possible to perform highly accurate angle detection for many years by performing self-calibration while being attached to a mechanical device such as a rotating machine. It is an object of the present invention to provide an angle detector that operates.

[0005]

A self-calibrating angle detector of the present invention is an angle detector for detecting a rotation angle of a disk by an angle data detecting head, wherein the angle data detecting head is installed. ° Position (360 /
2N) The Nth-order error component is obtained by using the angle data detected by the Nth-order error component detection head installed at the position rotated, and this Nth-order error component is detected by the angle data detection head. The angle data is self-calibrated by subtracting from.

In addition, a storage means for storing a table constituted by the Nth-order error component and the angle value is provided, and the angle data is self-calibrated by periodically referring to the table stored in the storage means. is there.

Further, the position of the Nth-order error component detecting head is A ° = 360 / (2 × N), and the precision error included in the angle data detected by the Nth-order error component detecting head at the A ° position.
When (total order error sum) is expressed as GS (A °), and shifting the error characteristic in the left term of (x) ° by a specified angle x ° is expressed as (x) ° shift, the Nth-order error is GN is N
When = 1, G1 = (GS (0 °) −GS (180 °)) /
2 and N is 2 or more, GN = {(GS (0
°) -GS (360 / (2 × N) °)) + (GS (0 °) -GS
(360 / (2 × N) °)) (360 / N) shift + (GS (0
°) -GS (360 / (2 × N) °)) (360 / N × 2) ° shift + ... + (GS (0 °) -GS (360 / (2 × N)
°)) (360 / N × K) ° shift} × (−1/2) × (1 /
N) (where K <N).

Further, the angle data detected by any of the Nth order error component detecting heads described above is obtained by the angle data detecting head or another Nth order error component detecting head. The calibration is performed using the data, and the average angle data obtained by averaging the plurality of calibrated angle data is output.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the self-calibrating angle detector according to the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, the angle detector of the present invention includes an angle data detecting head 2 including an LED and a light receiving element for detecting the rotational position of a disk 1 for detecting the rotational position of an encoder. Primary error detection head 3,
A secondary error detecting head 4, a fourth error detecting head 5, and an eighth error detecting head 6 are provided.

The first-order error detecting head 3, the second-order error detecting head 4, the fourth-order error detecting head 5 and the eighth-order error detecting head 6 are the same as the angle data detecting head 2 in the encoder body (see FIG. It is attached to the (not shown) side, and the configuration is the same as the angle data detecting head 2. Each error detecting head is arranged at a position rotated clockwise by 180 °, 90 °, 45 ° and 22.5 ° with respect to the angle data detecting head 2 about the center of the disk 1. There is. In the following, the position of the angle data detecting head 2 is 0 °, and the positions of the error detecting heads 3 to 6 are 180 °, 90 °, 45 ° and 22.5.
° position.

FIG. 2A shows a head 2 for detecting angle data.
It is a characteristic view which shows the angle data detected by. As shown in FIG. 2A, the angle data detecting head 2
The angle data according to (3) includes n-th (n is an integer) high-order error component such as a first-order harmonic component, a second-order harmonic component, and a fourth-order harmonic component. Each harmonic component is shown in FIG. 2 (b) to FIG. 2 (e).
Shown in.

The angle detector of the present invention performs the following processing in order to eliminate the error contained in the detected angle data. For convenience of description, first, the case of eliminating the second harmonic component will be described. A first position error characteristic (FIG. 3A) obtained by subtracting the angle data of the angle data detecting head 2 at the 0 ° position from the angle data of the secondary error detecting head 4 at the 90 ° position is obtained. .

Next, a second position error characteristic having a phase difference of 180 ° from the phase of the first position error characteristic shown in FIG. 3A is obtained. This second position error characteristic is shown in FIG. Then, by adding the first position error characteristic and the second position error characteristic shown in FIGS. 3A and 3B, the secondary error component shown in FIG. 3C is obtained. Since the gain of the secondary error component shown in FIG. 3C is 4 times, if the 1/4 times gain is removed from the angle data detected by the angle data detecting head 2, the secondary error component is removed. Angle data with components removed is obtained.

Similarly, each higher-order error component is obtained. When obtaining the primary error, the primary error detection head 3 is used,
As in the case shown in FIG. 3C, the gain is doubled 1
Since the next-order error component is obtained, if this gain of 1/2 is removed from the angle data detected by the angle-data detecting head 2, the first-order error component is removed to obtain the angle data. Further, if the fourth-order error detection head 5 is used,
Gain increased by a factor of 8 similar to that shown in FIG.
Since the next-order error component is obtained, if this gain of 1/8 is removed from the angle data detected by the angle-data detecting head 2, the fourth-order error component-free angle data is obtained. Further, if the 8th-order error detection head 6 is used, an 8th-order error component having a gain 16 times larger than that shown in FIG. 3C can be obtained.
If the multiplied data is removed from the angle data detected by the angle data detection head 2, the angle data from which the 8th order error component is removed can be obtained.

Here, N indicates the order of the error (Nth order component). A ° represents the head position A ° = 360 / (2 × N).
GS (A °) represents an accuracy error (total error of all orders) included in angle data detected by the head at the A ° position. G1, G
2, ..., GN mean first-order, second-order, ..., N-order error components. (x) ° shift means to shift the error characteristic in the left term of (x) ° by a specified angle x °.

Under these notation methods, the accuracy error detected from the angle data detecting head 2 at the 0 degree position is expressed as GS (0 °) = G1 + G2 + G3 + ... + GN. Further, the error of G1, G2, ..., GN is expressed by the following mathematical formula. G1 = (GS (0 °) −GS (180 °)) / 2 G2 = {(GS (0 °) −GS (90 °)) + (GS (0 °) −
GS (90 °)) 180 ° shift} × (−1/2) × (1 /
2) G3 = {(GS (0 °) -GS (60 °)) + (GS (0 °)-
GS (60 °)) 120 ° shift + (GS (0 °) -GS (6
0 °)) 240 ° shift} × (−1/2) × (1/3) G4 = {(GS (0 °) −GS (45 °)) + (GS (0 °) −
GS (45 °)) 90 ° shift + (GS (0 °) -GS (45
°)) 180 ° shift + (GS (0 °) -GS (45 °)) 27
0 ° shift} x (-1/2) x (1/4)

When N is 2 or more, the general formula is: GN = {(GS (0 °) -GS (360 / (2 × N) °)) +
(GS (0 °) -GS (360 / (2 × N) °)) (360 / N)
Shift + (GS (0 °) −GS (360 / (2 × N) °)) (3
60 / N × 2) ° shift + ・ ・ ・ + (GS (0 °) -GS
(360 / (2 × N) °)) (360 / N × K) ° shift} ×
(−1/2) × (1 / N) However, K <N.

By obtaining the error of each higher-order component as described above and subtracting it from the angle data detected by the angle data detecting head 2, the error contained in the angle data of the angle detector can be kept small. And as a result,
It is possible to provide an angle detector with high angle detection accuracy. Note that the above error calibration is performed in the block shown in FIG. 4, and each ROM serving as a storage unit stores a table composed of calibration values and angle values. Therefore, highly accurate angle data (position data) can be obtained by referring to the table stored in each ROM and performing error configuration periodically (for example, once a month) automatically. Can be output.

Further, in the above description, in order to calibrate the angle data detected by the angle data detecting head 2 which is the reference head, the primary error detecting head 3, the secondary error detecting head 4, and the quaternary error detecting head 4 are used. Although the case where the error detection head 5 and the 8th-order error detection head 6 are used has been described, since the heads 2 to 6 have the same configuration, the reference heads are sequentially arranged to the primary error detection head 3 and the secondary error detection head. The angle data may be similarly calibrated for the detection head 4, the 4th-order error detection head 5, and the 8th-order error detection head 6, and the angle data when the heads 2 to 6 are used as reference heads may be averaged.

At this time, by using only the Nth-order error component detecting head existing at the position rotated by (360 / 2N) ° with respect to the position where each reference head is installed, the Nth-order error component detection is performed. It is possible to remove only the error component of the order obtained by the reference head from the angle data detected by the reference head, or supplement the N-th order error component detection head appropriately and use the angle data detected by each head. The angle data may be calibrated by obtaining the Nth-order error component. If a plurality of reference heads are provided in this way, the averaged angle data finally obtained will be of extremely high accuracy.

[0022]

According to the self-calibration type angle detector of the present invention, in the angle detector for detecting the rotation angle of the disk by the angle data detecting head, with respect to the 0 ° position where the angle data detecting head is installed. (360 / 2N) ° rotated, the Nth-order error component is obtained using the angle data detected by the Nth-order error component detection head, and the Nth-order error component is detected by the angle data detection head. Since the angle data is self-calibrated by subtracting it from the obtained angle data, an error included in the angle data of the angle detector can be suppressed to a small value, and as a result, an angle detector with high angle detection accuracy can be provided. You can

Further, the apparatus is provided with a storage means for storing a table composed of the Nth-order error component and the angle value, and the angle data is self-calibrated by periodically referring to the table stored in the storage means. It is possible to provide a self-calibrating angle detector that can output highly accurate angle data over a long period of time.

Further, the position of the Nth-order error component detecting head is A ° = 360 / (2 × N), and the accuracy error included in the angle data detected by the Nth-order error component detecting head at the A ° position
When (total order error sum) is expressed as GS (A °), and shifting the error characteristic in the left term of (x) ° by a specified angle x ° is expressed as (x) ° shift, the Nth-order error is GN is N
When = 1, G1 = (GS (0 °) −GS (180 °)) /
2 and N is 2 or more, GN = {(GS (0
°) -GS (360 / (2 × N) °)) + (GS (0 °) -GS
(360 / (2 × N) °)) (360 / N) shift + (GS (0
°) -GS (360 / (2 × N) °)) (360 / N × 2) ° shift + ... + (GS (0 °) -GS (360 / (2 × N)
°)) (360 / N × K) ° shift} × (−1/2) × (1 /
N) (where K <N), it is possible to provide a self-calibrating angle detector that outputs highly accurate angle data with each higher-order error component removed.

Further, the angle data detected by any one of the Nth order error component detecting heads described above is obtained by the angle data detecting head or another Nth order error component detecting head. Since it calibrates using the data and outputs the average angle data obtained by averaging multiple angle data after calibration, it is possible to provide a self-calibrating angle detector that outputs extremely accurate angle data. it can.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a self-calibrating angle detector according to the present invention.

FIG. 2 is a characteristic diagram schematically showing each higher-order error component.

FIG. 3 shows a self-calibrating angle detector according to the present invention 2
It is a characteristic view which shows roughly a mode that a secondary error component is calculated.

FIG. 4 is a diagram showing a block configuration of a self-calibrating angle detector of the present invention.

[Explanation of symbols]

1 disc 2 Angle data detection head 3 Head for primary error detection 4 Secondary error detection head 5 4th-order error detection head 6 8th order error detection head

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F069 AA83 DD19 DD25 EE23 GG04                       GG07 GG11 HH13 HH15                 2F077 AA20 CC02 UU25                 5J022 DA02 DB02 DC04 DD01

Claims (4)

[Claims] 1. An angle detector for detecting a rotation angle of a disk with an angle data detecting head, wherein (36) is provided with respect to a 0 ° position where the angle data detecting head is installed.
The Nth-order error component is obtained by using the angle data detected by the Nth-order error component detection head installed at a position rotated by 0 / 2N) °, and the Nth-order error component is detected by the angle data detection head. A self-calibrating angle detector, wherein the angle data is self-calibrated by subtracting the angle data from the angle data. 2. A storage means for storing a table constituted by the Nth-order error component and the angle value is provided, and the angle data is self-calibrated by periodically referring to the table stored in the storage means. The self-calibrating angle detector according to claim 1, which is characterized in that. 3. The position of the Nth-order error component detecting head is set to A °.
= 360 / (2 × N), the accuracy error (total order error sum) included in the angle data detected by the N ° -order error component detection head at the A ° position is GS (A °), left of (x) ° When the error characteristic in the term is shifted by a specified angle x ° is expressed as (x) ° shift, the Nth-order error GN is G1 = (GS (0 °) − when N = 1. GS (180 °) / 2, and when N is 2 or more, GN = {(GS (0 °) −G
S (360 / (2 × N) °) + (GS (0 °) −GS (360
/ (2 × N) °)) (360 / N) shift + (GS (0 °) -G
S (360 / (2 × N) °)) (360 / N × 2) ° shift +
・ ・ ・ + (GS (0 °) -GS (360 / (2 × N) °)) (3
60 / N × K) ° shift} × (−1/2) × (1 / N) (where K <N), wherein the self-calibrating angle detector according to claim 1. 4. The angle data detected by any one of the Nth-order error component detection heads according to claim 1 is used for the angle data detection head or another Nth-order error component detection head. A self-calibration type angle detector characterized by calibrating using angle data obtained by a head and outputting average angle data obtained by averaging a plurality of calibrated angle data.