TW201632837A - Correction table creation device, encoder and correction table creation method - Google Patents

Abstract

The disclosure is to provide a correction table creation device that improves detection accuracy of a rotation angle position of an encoder 2. A correction table creation device 1 according to the present invention is a device that creates a correction table correcting an error of an encoder 2 detecting a rotation angle position from a signal of a detection element. A single rotation error calculation unit 110 calculates the error of the rotation angle position to be detected by the encoder 2 serving as a measured object by a single rotation with a highly accurate error detection device 3. An inherent error component calculation unit 120 calculates an inherent error component by performing a Fourier transformation of the calculated error of the single rotation. A correction table creation unit 130 performs an inverse Fourier transformation of only a value of a major error period component of the calculated peculiar error component, and creates a correction table with an amount of error in each rotation angle position as a correction value. A correction table storage unit 140 stores the created correction table in a storage unit of the encoder 2.

Description

Correction table creation device, encoder, and correction table creation method

The present invention relates to a correction table creation device for preparing a correction table for correcting an error of an encoder that detects a rotation angle position based on a signal of a detection element, an encoder to be used as a correction table creation target, and a correction table creation method.

Since the past, there has been known a device called a magnetic or optical encoder (rotary encoder) that can detect the rotational angular position of the shaft of a motor or the like as the rotational angular position data.

Further, in the encoder, there is a case where the rotation angle position can be converted into an incremental signal or the like, and the transmission is performed using two transmission lines called A and B phases, or the rotation angle position information capable of transmitting an absolute value.

According to Patent Document 1, there is described a technique for correcting a compensation value of an encoder, which is an encoder that detects an angular position of the rotating body based on an output signal of a sensor element that changes in conjunction with rotation of a rotating body. In order to correct the error of the detection result of the angular position and to correct the compensation value of the output signal, a correction step of correcting the compensation value every time the power supply to the encoder is started is performed, and in the correction step And performing a first correction step of detecting a deviation amount between the output signal and an ideal state, and correcting the compensation value based on the deviation amount, wherein the second multiple positive step is based on the first correction After the step, the compensation value is corrected by a gain smaller than the first correction step.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2011-47824

Here, the encoder of Patent Document 1 is provided with a fixed compensation value (correction value) indicating an ideal state of the rotational angle position of the encoder in the form of a correction table at the time of shipment from the factory. The correction sheet products are individually produced and memorized.

However, when the correction table is produced, even if the position of the rotation angle of the encoder is measured by the high-precision error detecting device, there is a problem that a random error (measurement error) of the measurement is generated. Therefore, it is difficult to produce a high-precision correction table.

The present invention has been made in view of such circumstances, and an object thereof is to provide a correction table creating apparatus capable of producing a highly accurate correction table.

The correction table creation device of the present invention is characterized in that it is a correction table for correcting an error of an encoder that detects a rotation angle position based on a signal of a detection element, and includes: a rotation one-time error calculation mechanism that utilizes a high-precision error The detecting device calculates an error of the rotation angle position detected by the encoder every one rotation, and the inherent error component calculating means calculates Fourier transform for each rotation error calculated by the one-turn error calculating means. Intrinsic error component; correction table creation means that performs inverse Fourier transform on the value of the main error period component of the inherent error component calculated by the inherent error component calculation means, and creates an error amount at each of the rotation angle positions as a correction The correction table of the value; and the correction table storage unit that stores the correction table created by the correction table creation unit in the memory mechanism of the encoder.

According to this configuration, the correction table is created using the main error period components of the inherent error components, and a highly accurate correction table can be produced. Therefore, it is possible to provide an encoder that detects the position of the rotation angle with high precision. Also, by saving the correction table directly to the code A correction table creating device capable of shortening the adjustment time can be provided.

In the encoder manufacturing apparatus of the present invention, the detecting element includes a movable object to be detected having a magnet having a pair of S poles and N poles magnetized, and an A phase magnetic induction opposite to the magnet a sensor and a B-phase magnetic induction sensor output a sinusoidal A-phase signal from the A-phase magnetic induction sensor corresponding to the displacement of the movable object to be detected, corresponding to the displacement of the movable object to be detected The B-phase magnetic induction sensor outputs a sinusoidal B-phase signal, and the phase difference between the A-phase signal and the B-phase signal is substantially π/2, and the encoder includes a rotation angle position calculation mechanism, and the rotation angle position calculation mechanism The angle position of the movable object to be detected is calculated by analyzing and analyzing the Lissajous waveform on the XY plane based on the A phase signal and the B phase signal, and the rotation angle position calculating means is for the movable object to be detected The above-mentioned Lissajous waveform of 2 cycles is calculated every one rotation.

According to this configuration, it is possible to create a high-precision correction table in accordance with the characteristics of the magnetic encoder. Further, since the position of the rotation angle can be detected by a pair of simple magnetization detecting elements, the adjustment step at the time of manufacture can be simplified.

The correction table creating apparatus of the present invention is characterized in that the main error period component is a periodic component of a power of two per revolution.

The A-phase signal and the B-phase signal system have two cycles per week. Therefore, by configuring in this manner, the error correction amount is determined by a power of two, whereby it is possible to manufacture a component that can correct most of the main error periods. Correct the table.

In the correction table creating apparatus of the present invention, the main error period component is at least one cycle component, two cycle component, four cycle component, and eight cycle component per rotation.

According to this configuration, it is possible to correct a component including the lower harmonic component to the third harmonic component of the harmonic component per revolution, and to perform sufficient correction so that accuracy can be produced. Correction table for good rotation angle position detection.

An encoder according to the present invention includes: a correction mechanism that reads the correction corresponding to the rotation angle position in a state in which the correction table is created by the correction table creation device and stored in the memory mechanism in a use state The value is corrected by the above correction value.

According to this configuration, since the high-precision correction table is stored in the memory unit in advance, it is not necessary to perform processing other than the correction by the correction table, and the error correction can be quickly performed.

The correction table creating apparatus according to the present invention is characterized in that the error is calculated in the one-rotation error calculation means or after the one-turn error calculation means is rotated to average the error of the plurality of rotations.

According to this configuration, the measurement error can be reduced, and an error table that accurately reflects the main error period component of the encoder can be created.

The correction table creation device according to the present invention is characterized in that the inherent error component calculation means or the inherent error component calculation means has a function of averaging the inherent error components of the plurality of rotations.

According to this configuration, the measurement error can be reduced, and an error table that accurately reflects the main error period component of the encoder can be created.

The method for manufacturing a correction table according to the present invention is characterized in that the correction table creation device creates a correction table for correcting an error of an encoder that detects a rotation angle position based on a signal of the detection element, In the correction table creation method, the error of the rotation angle position detected by the encoder to be measured every one rotation is calculated by using a high-precision error detecting device, and the Fourier transform is performed on the error per revolution. The inherent error component is measured, and only the value of the main error period component of the calculated inherent error component is inverse Fourier transformed, and the correction table in which the error amount at each of the rotation angle positions is used as the correction value is created, and the above-described correction table is created. The correction table is stored in the memory mechanism of the above encoder.

According to this configuration, the correction table is created using the main error period component, and a high-precision correction table can be produced.

According to the present invention, by creating a correction table in which the inherent error component of the encoder is extracted, it is possible to provide a correction table creation device that produces a high-precision correction table in which the measurement error is suppressed.

1‧‧‧correction table making device

2‧‧‧Encoder

3‧‧‧High-precision error detection device

4‧‧‧Motor

20‧‧‧Signal Processing Department

21‧‧‧Sensor wafer

22‧‧‧ movable object

110‧‧‧Rotation one-week error calculation unit

120‧‧‧Inherent Error Component Calculation Unit

130‧‧‧Amendment Table Production Department

140‧‧‧Amendment Table Maintenance Department

210‧‧‧Rotation angle position calculation unit

220‧‧‧Amendment

230‧‧‧Memory Department

400‧‧‧Revised form

A0‧‧‧A phase signal

A1‧‧‧A phase signal

A2‧‧‧A phase signal

A4‧‧‧A phase signal

A8‧‧‧A phase signal

B0‧‧‧B phase signal

B2‧‧‧B phase signal

B4‧‧‧B phase signal

B8‧‧‧B phase signal

L‧‧‧Rotation center axis

N‧‧‧ magnetic pole

S‧‧‧ magnetic pole

S101‧‧‧Steps

S102‧‧‧Steps

S103‧‧‧Steps

S104‧‧‧Steps

X‧‧‧Encoder adjustment system

Θ‧‧‧ angular position

Fig. 1A is a system configuration diagram of an encoder adjustment system according to an embodiment of the present invention.

Fig. 1B is a block diagram showing a control structure of the correction table creating apparatus shown in Fig. 1.

Figure 1C is a block diagram showing the control structure of the encoder shown in Figure 1.

Fig. 2 is a conceptual diagram showing a schematic configuration of a hardware of an encoder according to an embodiment of the present invention.

3(a) and 3(b) are conceptual diagrams showing a manner of calculating the rotational angle position of the encoder according to the embodiment of the present invention.

Fig. 4 is a flow chart showing a process of creating a correction table according to an embodiment of the present invention.

5(a) and 5(b) are conceptual diagrams showing the inherent error components of the encoder according to the embodiment of the present invention.

6(a) and 6(b) are conceptual diagrams showing the inherent error components of the encoder according to the embodiment of the present invention.

Fig. 7A is a graph showing an example of the result of the correction table creation processing in the embodiment of the present invention.

Fig. 7B is a graph showing an example of the result of the correction table creation processing in the embodiment of the present invention.

Fig. 7C is a graph showing an example of the result of the correction table creation processing in the embodiment of the present invention.

<Embodiment>

The configuration of the encoder adjustment system X according to the embodiment of the present invention will be described with reference to Fig. 1A. The encoder adjustment system X includes a correction table creation device 1, an encoder 2, a high-accuracy error detecting device 3, and a motor 4.

The correction table creation device 1 is a device for creating a correction table 400 for correcting the error of the encoder 2.

The correction table creation device 1 is configured, for example, as part of a manufacturing device or an adjustment device used when the encoder 2 is manufactured or when the factory is shipped and adjusted by maintenance. Specifically, the correction table creation device 1 includes a device dedicated to a logic board of a PC (Personal Computer). The correction table creation device 1 includes a control unit such as a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an HDD (Hard). Disk Drive, hard drive, or flash memory.

Furthermore, when the encoder 2 is actually used after shipment or after adjustment, the correction table creating apparatus 1 is removed.

The encoder 2 is an encoder 2 capable of detecting the rotational angular position based on the signal of the detecting element. The encoder 2 always detects the angle of the rotating body including the shaft coaxial with the motor 4 as the rotation angle position data.

The rotation angle position data includes a plurality of weeks of data indicating the number of rotations of the rotating body, and a data of one rotation of the rotation indicating the rotation angle of the rotating body including the movable object. Further, the rotation angle position data is data of a bit string in which the multi-week data is rotated and the data is continuously rotated within one week. Among them, the rotating multi-week data is the resolution of the digits to the tens of digits, and the data in one week is the resolution of the digits to hundreds of bits.

Further, the encoder 2 outputs the rotation angle position data to the correction table creation device 1 in accordance with an instruction from the correction table creation device 1. Further, the encoder 2 acquires the correction table 400 from the correction table creation device 1 (FIG. 1C).

Details of the manner of detecting the rotation angle by the encoder 2 will be described below.

The high-precision error detecting device 3 is used for an encoder for detecting a high-precision rotation angle for error detection. Therefore, the high-accuracy error detecting device 3 is also referred to as a "master encoder" or the like. The high-accuracy error detecting device 3 is coupled to the encoder 2 such that the central axis of rotation coincides with the central axis of rotation L, and the encoder 2 can detect the same rotational angle position as that of the encoder 2 with higher accuracy. However, even for the high-precision error detecting device 3, there is a specific range of angular errors.

Further, the high-accuracy error detecting device 3 acquires the rotation angle position data based on the control signal from the correction table creating device 1, for example, and outputs it to the correction table creating device 1.

Furthermore, the high-precision error detecting device 3 is also removed during use.

The motor 4 is controlled based on the rotational angular position data from the encoder 2 to rotate the rotating body about the central axis of rotation L.

The motor 4 includes a servo motor such as a rotor, a bearing, a stator, and a bracket, and is capable of performing high-precision rotation control.

The functional configuration of each part will be described in more detail with reference to Figs. 1B and 1C.

According to FIG. 1B, the correction table creation device 1 includes a rotation one-time error calculation unit 110 (rotation one-time error calculation unit), an inherent error component calculation unit 120 (inherent error component calculation unit), a correction table creation unit 130 (correction table creation unit), and And a correction table storage unit 140 (correction table storage means) and the like.

The one-rotation error calculation unit 110 calculates the error of the rotational angle position detected by the encoder 2 per revolution by the high-accuracy error detecting device 3. Specifically, the one-rotation error calculation unit 110 compares the rotational angle position detected by the encoder 2 with the rotational angle position detected by the high-accuracy error detecting device 3, and calculates the difference (position error) per one rotation.

The inherent error component calculation unit 120 calculates the inherent error component by performing Fourier transform on the error per rotation calculated by the one-rotation error calculation unit 110. Specifically, the inherent error component calculation unit 120 calculates the frequency component by the Discrete Fourier Transformation (DFT) method such as FFT (Fast Fourier Transform) for the error per rotation. The inherent error component calculation unit 120 extracts a specific periodic component from the calculated frequency component as an inherent error component. In the present embodiment, the inherent error component calculating unit 120 obtains the frequency component by the power of ²⁰ cycles comprising of two components, the main error period component extracted. Further, the main error period component includes at least one cycle component, two cycle component, four cycle component, and eight cycle component. I.e., the inherent error component calculating section 120 obtains a power of 2, i.e. ^{20, 21, 22, 23} of the periodic component. Specifically, the intrinsic error component calculation unit 120 acquires a one-cycle component that is a term corresponding to the fundamental period of the one-rotation of the Fourier series expansion, is a two-time term, and has a periodic component that changes two cycles per rotation of the axis, It is a period component of four times and that the axis changes by four cycles per rotation of the axis, and a cycle component that is eight times and that changes by eight cycles per rotation of the axis. By obtaining these inherent error components, the main error component of the encoder can be extracted. Details of the error originating from the inherent error components of each cycle will be described below.

Furthermore, the inherent error component calculating section 120 also at the time of withdrawal main component error period, i.e., the acquisition component 16 cycles of ²⁴ as a main component an error component. Further, the inherent error component calculation unit 120 can also acquire the 18-cycle component.

The correction table creation unit 130 performs Fourier inverse conversion on the value of the main error period component of the inherent error component calculated by the inherent error component calculation unit 120, and creates a correction table 400 in which the error amount at each rotation angle position is used as the correction value (Fig. 1C). The correction table creation unit 130 acquires, for example, only the cycle component of the power of 2 as the main error component. Specifically, the correction table creation unit 130 performs the inverse discrete Fourier Transformation (IDFT) by the IFFT (Inverse Fast Fourier Transform) or the like only for the period component of the obtained power of 2, And make a correction table 400 for one rotation per revolution. At this time, when the periodic components of 2 ⁰ , 2 ¹ , 2 ² , and 2 ^{3 are} extracted, the data of the number of rotations per revolution obtained by the IFFT calculation becomes the correction table 400. As described above, by creating the correction table 400 only with the main error period component, it is possible to reduce the influence of the angular error of the specific range of the high-accuracy error detecting device 3, and it is possible to reliably reflect the inherent error of the encoder 2.

The correction table storage unit 140 stores the correction table 400 created by the correction table creation unit 130 in the storage unit 230 of the encoder 2. The correction table creating device 1 memorizes the created correction table 400 in the memory unit 230 of the encoder 2 by a specific control signal.

According to FIG. 1C, the encoder 2 includes a rotation angle position calculation unit 210 (rotation angle position calculation means), a correction unit 220 (correction mechanism), and a memory unit 230 (memory mechanism).

The rotation angle position calculation unit 210 calculates a rotation angle position based on the signal of the detection element. When the correction table 400 is created by the correction table creation device 1 , the rotation angle position calculation unit 210 does not correct the calculated rotation angle position, and transmits it to the correction table creation device 1 .

The manner of calculating the rotational angle position in the present embodiment will be described below.

In the use state, the correction unit 220 reads the correction value corresponding to the rotation angle position detected by the rotation angle position calculation unit 210 in the use state from the correction table 400 stored in the storage unit 230, and corrects the error using the correction value. . Specifically, the correction unit 220 converts the rotation angle position into the following division angle position, and acquires a correction value corresponding to the division angle position from the correction table 400. The correction unit 220 corrects the correction value by adding or subtracting the rotation angle position, and calculates the rotation angle position as the final rotation angle position.

In the use state, the corrected rotation angle position is transmitted to a host device (not shown) or the like. At this time, the correction unit 220 sets the rotation angle position as the edge of the signal of HL (H indicates a high level signal and L indicates a low level signal), for example, a phase shifted by 90 degrees, respectively, by the two transmission lines of the A phase and the B phase. Incremental signaling.

The memory unit 230 is a non-transitory memory medium such as a RAM, a ROM, or a flash memory included in the signal processing unit 20 (FIG. 2) described below. The detected rotation angle position data, temporary data, control program, and the like are stored in the storage unit 230.

The memory unit 230 stores a correction table 400 created by the correction table creation device 1.

As described above, the correction table 400 is a table created by performing Fourier inverse conversion only on the value of the main error period component of the inherent error component of the angular position of the encoder 2 detected by the high-accuracy error detecting device 3. The correction table 400 is, for example, a periodic component of 2 ⁰ , 2 ¹ , 2 ² , and 2 ³ among the periodic components of the harmonics per revolution, that is, components including the lower to the third harmonic components. A table to make corrections. Specifically, the correction table 400 has an error amount at each rotation angle position as a correction value. In the encoder 2, by correcting the rotation angle position using the correction table 400, it is possible to perform sufficient correction and to perform position detection with high accuracy.

Furthermore, the correction table 400 may not memorize the correction values for all the rotational angle positions corresponding to the angular resolution of the encoder 2. In this case, the correction table 400 memorizes the correction value corresponding to the division angle position obtained by dividing the rotation by one rotation with a specific division number. Specifically, the correction table 400 stores a correction value corresponding to a divided angular position such as an 8-bit to a 16-bit, for example, even when the angle resolution of the encoder 2 is 20 bits or more. Further, when such a correction value is read in the use state, linear interpolation, spline interpolation, or the like may be used.

[How to calculate the rotation angle position]

Here, a method of calculating the rotational angle position by the encoder 2 according to the embodiment of the present invention will be described with reference to FIGS. 2 and 3.

According to FIG. 2, the encoder 2 includes a detecting element and a signal processing unit 20. The detecting element includes a movable object 22 having a pair of magnets in which the magnetic poles of the S pole and the N pole are magnetized, and a sensor wafer 21 facing the magnet.

The sensor chip 21 is a sensor IC of a magnetoresistive element (integrated circuit) Road) and so on.

As shown in FIG. 2, the sensor wafer 21 is disposed on the rotation center axis L of the magnet, and is opposed to the magnetization boundary portion of the magnet in the direction of the rotation center axis L. Therefore, the magnetic induction film of the sensor wafer 21 can detect the rotating magnetic field with the magnetic field intensity above the saturation sensitivity region of the resistance value.

Further, the sensor wafer 21 internally includes an A-phase magnetic induction sensor having a phase difference of 90° (π/2) with respect to the phase of the magnet, and a B-phase magnetic induction sensor. The A-phase signal and the B-phase signal from the sensor chip 21 are amplified by an amplifier and input to the signal processing unit 20.

The signal processing unit 20 includes a microcontroller including a recording medium, a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), and the like. Further, the signal processing unit 20 performs A/D (Analog to Digital) conversion on the A-phase signal and the B-phase signal amplified by the amplifier.

Further, the signal processing unit 20 detects a rotation angle position, a rotation speed, and the like based on the A/D converted signal. Therefore, the signal processing unit 20 functions as the rotation angle position calculation unit 210 and the correction unit 220 by executing a control program (not shown) stored in the memory medium.

Here, a method of calculating the rotational angle position based on the A-phase signal and the B-phase signal by the rotational angle position calculating unit 210 will be described with reference to FIG.

According to FIG. 3(a), the A-phase magnetic induction sensor outputs a sinusoidal A-phase signal (sin) corresponding to the displacement of the movable object 22, and the B-phase magnetic induction sensor outputs a sinusoidal B-phase. Signal (cos). Further, the phase difference between the A-phase signal and the B-phase signal is approximately π/2 (90°). Further, in the graph of Fig. 3(a), the horizontal axis represents the angle (°), and the vertical axis represents the value.

According to FIG. 3(b), the rotation angle position calculating unit 210 calculates the phase signal and the phase B signal based on the phase A signal. The angular position θ of the movable object 22 is detected by setting the X-axis as the B-phase signal and the Y-axis as the Lissajous waveform on the XY plane of the A-phase signal and analyzing it.

3(a) and 3(b), the rotation angle position calculation unit 210 calculates a Lissajous waveform of two cycles per rotation of the movable object 22. The reason is that the A-phase magnetic induction sensor and the B-phase magnetic induction sensor respectively detect only the strength of the magnetic field. Therefore, the rotation angle position calculation unit 210 calculates which section the Lissajous waveform formed by the A-phase signal (sin) and the B-phase signal (cos) is located by a Hall element or the like (not shown). The rotation angle position calculation unit 210 calculates the final rotation angle position based on the angular position θ of the movable object 22 and the interval. The rotation angle position is an absolute value (absolute value), and is an integer value expressed by a unit obtained by decomposing one cycle using the angle resolution R. The value of the angle resolution R is 2 ^{^} 20=1048576 in the case of a detection element using a resolution of 20 bits. Further, as the integer value, the complement of 2 included in the symbol system 1 bit can also be used.

[correction table creation processing]

Next, the rotation angle position detecting process by the encoder adjusting system X according to the embodiment of the present invention will be described with reference to Figs. 4 to 7C.

In the processing of this embodiment, first, an error is calculated based on the rotational angle position obtained from the high-precision error detecting device 3 and the encoder 2. Second, the main error component is extracted from the error calculated by the FFT. The correction table 400 is created by performing IFFT only on the extracted main error component. The prepared correction table 400 is stored in the encoder 2.

The rotation angle position detection processing of the present embodiment mainly uses a control unit (not shown) of the correction table creation device 1 to cooperate with each part and execute a control program stored in a memory unit (not shown) using a hardware resource (not shown). Graphic). Further, the memory unit of the correction table creating device 1 temporarily stores the rotation angle position data acquired from the encoder 2 and the high-accuracy error detecting device 3, and the rotation-circumference error table and the correction table 400 calculated based on the rotation angle position data. Etc., for processing.

Hereinafter, using the flowchart of FIG. 4, the rotation angle position detection will be described in accordance with each step. Details of the processing.

(Step S101)

First, the one-turn error calculation unit 110 performs a one-turn error calculation process.

The one-rotation error calculation unit 110 performs control for rotating the motor 4 one or more times, and transmits a control signal to the encoder 2 and the high-accuracy error detecting device 3 to transmit a rotation angle position. At this time, the one-rotation error calculation unit 110 transmits a control signal to the encoder 2 by serial communication or the like, and changes it to an operation mode such as "adjustment mode". In the "adjustment mode", the encoder 2 does not use the correction table 400 stored in the memory unit 230, and transmits the rotation angle position to the correction table creation device 1 without correcting the rotation angle position.

The one-rotation error calculation unit 110 acquires the respective rotation angle positions from the encoder 2 and the high-accuracy error detection device 3. The one-rotation error calculation unit 110 calculates the difference between the rotational angle position of the high-accuracy error detecting device 3 and the rotational angle position of the encoder 2 as the error E. Further, the one-rotation error calculation unit 110 temporarily stores the calculated error E as a one-turn error table corresponding to each rotation angle position. At this time, the one-rotation error calculation unit 110 stores the one-turn error table as a set of sample points corresponding to the division angle position.

(Step S102)

Next, the inherent error component calculation unit 120 performs an inherent error component calculation process.

The inherent error component calculation unit 120 performs one-dimensional FFT on the one-rotation error table, and calculates each frequency component as an inherent error component. Further, the inherent error component calculation unit 120 extracts one cycle component, two cycle component, four cycle component, and eight cycle component among the calculated inherent error components as the main error cycle component. Due to the characteristics of the detecting element, the analysis of the Lissajous wave motor 4 has two cycles per revolution and is a power of two. Therefore, the main error of the encoder 2 can be corrected by extracting only the periodic components.

The details of the inherent error components in the detection of the rotational angular position of the encoder 2 will be described with reference to Figs. 5 to 6 .

Fig. 5(a) is a conceptual diagram of a one-cycle component. Figure 5 (a) shows the high precision error detection A graph of the A-phase signal A0 of the device 3 and the A-phase signal A1 of the encoder 2 having an error of one cycle component. The one-cycle component is mainly an error associated with the mounting error, that is, the deviation from the axis of the rotation center axis L of the movable object 22 of the encoder 2. In the graph of Fig. 5(a), the horizontal axis represents the angle (°), and the vertical axis represents the value. If specifically stated, the error occurs due to the deviation of the center of the revolution of the magnet. Since the magnet revolves while rotating, the value changes later if the magnet is close to the magnetoresistive element, and the value changes earlier if the magnet is away from the magnetoresistive element.

Fig. 5(b) is a conceptual diagram of a 2-period component. Fig. 5(b) shows the Lissajous waveform of the A-phase signal A0 and the B-phase signal B0 of the encoder 2 having the high-precision error detecting device 3 and the A-phase signal A2 and the B-phase signal B2 of the encoder 2 having the error of the two-period component . The error of the two-cycle component mainly indicates an error related to the deviation of the central axis of the Lissajous waveform, that is, the waveform of the A-phase signal and the B-phase signal. The error of the two-cycle component is caused by an annual change or a temperature change, an error in the resistance of the bridge of the A-phase magnetic induction sensor and the B-phase magnetic induction sensor, and the like.

Fig. 6(a) is a conceptual diagram of a 4-cycle component. Fig. 6(a) shows Lisa, which has the same A-phase signal A0 and B-phase signal B0 as in Fig. 5(b), and A-phase signal A4 and B-phase signal B4 of the encoder 2 having an error of four periods. Such as waveforms. The error of the 4-cycle component is the error expressed by the Lissajous waveform as an elliptical shape. The error of the four-cycle component includes an error due to the shape of the sensor wafer 21, the shape of the magnet, and the relationship between the magnetic fluxes.

Figure 6(b) is a conceptual diagram of the 8-cycle component. Fig. 6(b) shows A-phase signals A0 and B, which are the same as those of Figs. 5(b) and 6(a), and A-phase signals A8 and B of the encoder 2 having an error of 8 cycles. The phase signal B8 has a Lissajous waveform. The error of the 8-cycle component is an error expressed in the Lissajous waveform in such a manner that the point between the 1/4 arcs connecting the vertices of π/2 becomes the inner side. The error of the 8-cycle component is an error due to the characteristics of the magnetoresistive element, and mainly includes an error caused by the saturation of the change in the resistance value generated by the magnetic flux of the magnetoresistive element.

Fig. 7A shows the result of calculating the periodic component of the magnetic encoder 2 for the prototype. An example of fruit. In the graph, the horizontal axis represents the periodic component, and the vertical axis represents the value of each periodic component (spectral intensity).

It can be seen that the spectral intensity of the 1, 2, 4, and 8 periodic components is relatively high and dominates. Therefore, the main error component of the encoder 2 can be extracted by using one cycle component, two cycle component, four cycle component, and eight cycle component among the respective frequency components as the inherent error component.

Further, in the total error component, there are also 16 cycle components of about 1% to 2%, and there are also 18 cycle components of about 0.5%. Regarding the other components, the random error (white noise) of the measurement by the high-precision error detecting device 3 and the encoder 2 is considered. The random error includes sliding of bearings, etc., thermal noise, power noise, and the like.

(Step S103)

Next, the correction table creation unit 130 performs a correction table creation process.

The correction table creation unit 130 performs Fourier inverse conversion on only the value of the main error period component extracted from the calculated inherent error component.

Specifically, the correction table creation unit 130 executes the one-dimensional IFFT using only the values of the one-cycle component, the two-cycle component, the four-cycle component, and the eight-cycle component, which are the extracted inherent error components. Specifically, the correction table creation unit 130 calculates a value corresponding to the division angle position at which the rotation is divided by a specific number of divisions in each of the rotation angle positions by the IFFT. The correction table creation unit 130 creates the correction table 400 using the calculated value as the correction value, and temporarily stores it.

FIG. 7B is a graph showing a graph of the one-turn error table calculated by the one-turn error calculation unit 110 and an example of the correction table created by the correction table creation unit 130. In the graph, the horizontal axis represents the division angle position, and the vertical axis represents the correction value.

Fig. 7C is an enlarged view of a portion of Fig. 7B.

As described above, the correction table 400 created by the correction table creating unit 130 only performing inverse Fourier transform on the value of the main error period component indicates a more gentle change from the one-turn error table. That is, it can be seen that the random error of the measurement is reduced, and the inherent error component is well reflected. When the encoder 2 is corrected by the mitigation correction table 400, the accuracy of the measurement is improved.

(Step S104)

Next, the correction table storage unit 140 performs a correction table storage process.

The correction table storage unit 140 transmits a specific control signal to the encoder 2, for example, to control the "correction table 400 overwrite mode". In the "correction table 400 overwrite mode", the encoder 2 stores the correction table 400 transmitted from the correction table creation device 1 in the storage unit 230.

The correction table storage unit 140 transmits the created correction table 400 to the encoder 2 that has become the "correction table 400 overwrite mode". Thereby, the correction table storage unit 140 causes the correction table 400 to be stored in the storage unit 230 of the encoder 2.

By the above steps, the correction table creation processing of the embodiment of the present invention is terminated.

[Main effects of the embodiment of the present invention]

By configuring in the above manner, the following effects can be obtained.

Previously, when the error of the rotational angle position of the encoder was corrected, the error between the position of each rotation angle and the high-precision error detecting means was measured, and the value was stored in the encoder as a correction table. However, the measurement error is included in the measurement.

On the other hand, the correction table creating apparatus 1 according to the embodiment of the present invention is characterized in that the correction table 400 for correcting the error of the encoder 2 that detects the rotational angle position based on the signal of the detecting element is included, and includes: The one-period error calculating unit 110 calculates an error of the rotational angle position detected by the encoder 2 per revolution by the high-precision error detecting device 3, and the inherent error component calculating unit 120 calculates the error by the one-turn error calculating unit 110. The Fourier transform is performed for each revolution, and the inherent error component is calculated. The correction table creation unit 130 performs Fourier inverse transformation on only the value of the main error period component of the inherent error component calculated by the inherent error component calculation unit 120. The error amount at each rotation angle position is used as a correction value correction table 400; and the correction table storage unit 140 stores the correction table 400 created by the correction table creation unit 130 in the memory unit 230 of the encoder 2.

According to this configuration, the correction amount of the error can be calculated from the main error period component extracted from the inherent error component, whereby the high-precision correction table 400 can be produced. In other words, by making the correction table 400 using the main error period component, it is possible to suppress the measurement error when the error is measured by the high-accuracy error detecting device 3. Therefore, in the encoder 2 including the correction table 400, the rotation angle position can be accurately detected.

Further, the correction table creation device 1 of the present embodiment can directly store the error correction table 400 of the error in the memory unit 230 of the encoder 2. Therefore, the rotation angle position can be quickly adjusted. In addition, the labor and time for error adjustment can be reduced, and the adjustment cost can be reduced.

In the encoder 2 of the embodiment of the present invention, the detection device includes a movable object 22 having a pair of magnets in which the magnetic poles of the S pole and the N pole are magnetized, And the A-phase magnetic induction sensor and the B-phase magnetic induction sensor opposite to the magnet, and output the sinusoidal A-phase signal from the A-phase magnetic induction sensor corresponding to the displacement of the movable object 22, and the movable detection is performed The displacement of the object 22 correspondingly outputs a sinusoidal B-phase signal from the B-phase magnetic induction sensor, and the phase difference between the A-phase signal and the B-phase signal is substantially π/2, and the encoder 2 includes a rotation angle position calculating unit 210. The rotation angle position calculation unit 210 calculates the Lissajous waveform on the XY plane based on the A-phase signal and the B-phase signal, and analyzes the waveform to detect the angular position of the movable object 22, and the rotation angle position calculation unit 210 Each time the movable object 22 is rotated, a two-cycle Lissajous waveform is calculated.

According to this configuration, it is easy to calculate the main error period component of the inherent error component, and it is possible to produce the correction table 400 with high accuracy. Further, by using the encoder 2, it is easy to adjust the position of the rotation angle in the manufacturing step, and the encoder 2 detects the position of the rotation angle by the detecting element having a pair of magnetized simple magnets.

The encoder 2 according to the embodiment of the present invention is characterized in that the main error period component is a periodic component of a power of two per revolution.

Here, the Lissajous wave motor 4 has two cycles per revolution. Thus, by configuring in this manner, the correction amount is calculated based on the main error component of the power of 2, and a correction table that can correct almost all of the inherent errors of the encoder 2 can be created.

The correction table creating apparatus 1 according to the embodiment of the present invention is characterized in that the main error period component is at least one cycle component, two cycle component, four cycle component, and eight cycle component per rotation.

Here, a periodic component, component 2 cycle, 4 cycle-based component and the periodic component 8 2 ^0, 2 ^1, 2 ^2, components of a power of 2, a so-called ^23's. In other words, by using the inherent error component including the lower harmonic component to the third harmonic component among the harmonic components per revolution as the main error component, sufficient correction can be performed, and the correction can be performed well. A correction table 400 reflecting the inherent error components is reflected. Therefore, it is possible to perform the rotation angle position detection with high accuracy by the encoder 2.

The encoder 2 according to the embodiment of the present invention includes a correction unit 220 that reads and uses the rotation angle of the correction table 400 prepared by the correction table creation device 1 and stored in the storage unit 230. The position corresponds to the correction value, and the correction value is used to correct the error.

According to this configuration, since the high-precision correction table 400 is memorized in the memory unit 230 in advance, the error correction can be performed only by reading the correction table 400, so that the measurement of the rotational angle position with high accuracy can be quickly performed. In this case, it is not necessary to perform the correction by the correction formula or the like other than the correction table 400, and the correction processing load of the signal processing unit 20 can be reduced, and the rotation angle position can be quickly detected and output. Moreover, since the high-precision correction table 400 is stored in the memory unit 230, the frequency of adjustment of the rotation angle position detection due to the cracking of the year can be reduced.

[Other Embodiments]

Furthermore, in the above embodiment, the correction table creation device 1 calculates the rotation angle position of the high-accuracy error detecting device 3 and the encoder 2 to calculate an error.

However, the high-precision error detecting device 3 may directly acquire the rotational angle position of the encoder 2 and calculate an error, and transmit only the error to the correction table creating device 1 and calculate the rotation error of the correction table creating device 1 The unit 110 obtains the error. Further, the high-accuracy error detecting device 3 itself may be an inspection device having the function of the correction table creating device 1.

Further, in the above-described embodiment, the correction table creation device 1 is described by directly recording the correction table 400 and storing it in the encoder 2.

However, after the correction table 400 is created by the correction table creation device 1, it may be stored in an external memory medium such as a flash memory card or the like, and the external memory medium or the like may be loaded on the encoder 2.

By configuring in this manner, the configuration of the encoder adjustment system can be made flexible, and the cost can be reduced.

Moreover, in the above-described embodiment, an example in which the correction table creation device 1 acquires an error per rotation and creates an error table, and then creates the correction table 400 is described.

However, the error of the complex number may be calculated from the high-accuracy error detecting device 3 and the encoder 2, and may be averaged in the one-turn error calculating means or the one-turn error calculating means so that the errors can be averaged. The function of the transformation. Alternatively, the error of the complex number may be calculated from the high-accuracy error detecting device 3 and the encoder 2, and the inherent error component of the complex number may be calculated by the inherent error component calculating means for the error of the complex number, and each inherent error may be obtained. In this way, the components are averaged, and in this way, the intrinsic error component calculation means or the inherent error component calculation means has a function of averaging. Further, the prepared correction table 400 itself may be subjected to post-processing such as smoothing.

Thereby, the measurement error can be reduced, and an error table that accurately reflects the main error period component of the encoder 2 can be produced.

In addition, the configuration and the operation of the above-described embodiments are not limited, and may be appropriately modified without departing from the gist of the invention.

1‧‧‧correction table making device

2‧‧‧Encoder

3‧‧‧High-precision error detection device

110‧‧‧Rotation one-week error calculation unit

120‧‧‧Inherent Error Component Calculation Unit

130‧‧‧Amendment Table Production Department

140‧‧‧Amendment Table Maintenance Department

Claims (9)

A correction table creation device characterized in that it is a correction table for correcting an error of an encoder that detects a rotation angle position based on a signal of a detection element, and includes: a rotation one-time error calculation mechanism that uses high-precision error detection The device calculates an error of the rotation angle position detected by the encoder every one rotation; the inherent error component calculation means calculates the inherent error by performing Fourier transform on the error per revolution calculated by the one-turn error calculation means. a component; a correction table creation unit that performs Fourier inverse transformation on only the value of the main error period component of the inherent error component calculated by the inherent error component calculation means, thereby producing an error amount at each of the rotation angle positions as a correction value The correction table and the correction table storage unit store the correction table created by the correction table creation unit in a memory mechanism of the encoder. The correction table creating device of claim 1, wherein the detecting element includes a movable object to be detected by a magnet having a pair of S poles and N pole magnetic poles, and an A phase magnetic induction opposite to the magnet a sensor and a B-phase magnetic induction sensor; outputting a sinusoidal A-phase signal from the A-phase magnetic induction sensor corresponding to the displacement of the movable object to be detected, and corresponding to the displacement of the movable object to be detected The B-phase magnetic induction sensor outputs a sinusoidal B-phase signal, and the phase difference between the A-phase signal and the B-phase signal is substantially π/2; and the encoder includes a rotation angle position calculation mechanism, and the rotation angle position is calculated The output mechanism calculates and analyzes the Lissajous waveform on the XY plane based on the A phase signal and the B phase signal, thereby detecting an angular position of the movable object to be detected; and the rotation angle position calculating means is the movable The above-mentioned Lissajous waveform of 2 cycles was calculated every rotation of the test object. The correction table creating device of claim 2, wherein the main error period component is a periodic component of a power of two per revolution. The correction table creation device of claim 3, wherein the main error period component is at least one cycle component, two cycle component, four cycle component, and eight cycle component per rotation. An encoder, comprising: a correction mechanism, which is prepared by the correction table creation device according to any one of claims 1 to 4 and stored in the correction table of the memory mechanism, read and used The correction value corresponding to the rotation angle position is corrected by the correction value. The encoder of claim 5, wherein the rotation one-cycle error calculation means or the one-rotation error calculation means has a function of averaging errors of the plurality of rotations. The encoder according to claim 5, wherein the intrinsic error component calculating means or the intrinsic error component calculating means has a function of averaging respective intrinsic error components of the plurality of rotations. The correction table creating device of claim 1, wherein the main error period component is a periodic component of a power of two per revolution. A method for manufacturing a correction table, characterized in that it is performed by a correction table creation device, and the correction table creation device is configured to detect a signal according to a detection element A correction table for correcting an error of an encoder at an angular position, and the correction table is produced by using a high-precision error detecting device to calculate the rotation angle position detected by the encoder to be measured every one rotation Error; the inherent error component is measured by performing Fourier transform on the calculated error per revolution; and only the value of the main error period component of the calculated inherent error component is inverse Fourier transformed, thereby making each of the above rotation angle positions The error amount is used as the correction table of the correction value; and the created correction table is stored in the memory mechanism of the encoder.