JP2011196868A - Apparatus for correction of position data, encoder, motor system, and position data correction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position data correction apparatus, along with an encoder, motor system and position data correction method, capable of correcting an error more easily and properly.SOLUTION: The position data correction apparatus 100 includes: a pitch specification part 102 for specifying a positioned pitch, based on position data of a moving body generated based on a detection signal fluctuating by one period with one pitch; a pitch inside position specification part 101 for specifying a positioned pitch inside position based on the position data; a memory 103 in which each parameter of a linear error function is recorded beforehand in each of a plurality of sections set respectively in each pitch; a parameter acquisition unit 104 for acquiring a parameter corresponding to a section based on the specified pitch and the pitch inside position; an error correction value calculation unit 105 for calculating an error correction value of the pitch inside position based on the parameter; and a position data correction unit 107 for correcting position data based on the error correction value.

Description

  The present invention relates to a position data correction device, an encoder, a motor system, and a position data correction method.

An encoder is used to measure physical quantities such as the position and speed of the moving body.
This encoder is roughly classified into a rotary type (hereinafter also referred to as “rotary”) and a linear type (hereinafter also referred to as “linear”) according to the moving direction of the moving body.

  The rotary encoder is also referred to as a rotational position detection device or the like, and detects the position (angle), speed (rotational speed), etc. of the moving body (rotating body). On the other hand, the linear encoder is also referred to as a linear position detection device or the like, and detects the position and speed of the moving body.

  As such an encoder, an encoder that acquires a detection signal that periodically changes in accordance with the amount of movement of the moving body and detects the position or the like by calculating the detection signal is widely used. ing. On the other hand, for example, a position data correction device such as that disclosed in Patent Document 1 is used as the encoder, and an error included in the detection signal may be corrected by the position data correction device.

International Publication No. 2007/060840

  For example, the position data correction apparatus described in Patent Document 1 records a position error caused by a delay in movement time or a manufacturing error included in the position detection mechanism as a correction function that is specified in advance and expressed as a power series. The error is corrected by the error correction value obtained from this correction function. According to such a position data correction apparatus, it is not necessary to record an error correction value for each position data, so that the amount of data to be recorded can be reduced. In the position data correction apparatus described in Patent Document 1, the position error is a position error that changes sinusoidally within one period (within one pitch) of a periodic detection signal.

  On the other hand, in an actual encoder, for example, in the case of an optical encoder, reflected light or external light from a member different from the design causes an error, or stray light such as light from another light source causes an error. Sometimes. In this case, the position error often includes not only a sine wave component but also a non-sine wave component.

  It is difficult to correct a position error including a non-sinusoidal component with the position data correction apparatus described in Patent Document 1. On the other hand, when accurately reproducing position errors including non-sinusoidal components, for example, by increasing the power series order or using Fourier transform, the amount of data to be stored increases. The amount of calculation also increases. Therefore, it is difficult to appropriately and easily correct a position error including a non-sinusoidal component.

  Therefore, the present invention has been made in view of such problems, and an object of the present invention is to provide a position data correction device, an encoder, and a motor that can correct errors more easily and appropriately. A system and a position data correction method are provided.

In order to solve the above-described problem, according to an aspect of the present invention, position data representing a position of the moving body generated based on a detection signal whose amplitude varies by one period each time the moving body moves by one pitch. A pitch specifying unit for specifying the pitch at which the moving body is located, and
Based on the position data, an in-pitch position specifying unit that specifies an in-pitch position where the moving body is located;
When a position in the pitch is inputted, a linear error function parameter for deriving an error correction value at the position in the pitch is recorded in advance for each of a plurality of sections set for the pitch, and
A parameter acquisition unit that acquires, from the memory, the parameter corresponding to the section in which the moving body is located based on the pitch specified by the pitch specifying unit and the in-pitch position specified by the in-pitch position specifying unit. When,
Based on the parameters acquired by the parameter acquisition unit, an error correction value calculation unit that calculates an error correction value of the position within the pitch specified by the position determination unit within the pitch, and
A position data correction unit that corrects the position data generated by the position data generation unit based on the error correction value calculated by the error correction value calculation unit;
A position data correction apparatus is provided.

In addition, the parameter is set for each of the four or more sections for each of the pitches so that the change of the error correction value by the linear error function becomes two or more triangular wave shapes within the one pitch.
The parameter in at least one or more of the pitches may be set so that absolute values of two or more extreme values in the two or more triangular wave shape error correction values are different.

  The parameter may include the length of each section in the pitch.

  The position data correction is performed by filtering the error correction value calculated by the error correction value calculation unit based on the pitch specified by the pitch specifying unit and the position in the pitch specified by the in-pitch position specifying unit. You may further have the filter output to a part.

In order to solve the above-described problem, according to another aspect of the present invention, a detection signal acquisition unit that acquires at least a detection signal whose amplitude fluctuates by one period every time the moving body moves by one pitch;
Based on the detection signal acquired by the detection signal acquisition unit, a position data generation unit that generates position data representing the position of the moving body;
Based on the position data generated by the position data generation unit, a pitch specifying unit that specifies the pitch at which the moving body is located;
Based on the position data generated by the position data generation unit, an in-pitch position specifying unit that specifies an in-pitch position where the moving body is located;
When a position in the pitch is inputted, a linear error function parameter for deriving an error correction value at the position in the pitch is recorded in advance for each of a plurality of sections set for the pitch, and
A parameter acquisition unit that acquires, from the memory, the parameter corresponding to the section in which the moving body is located based on the pitch specified by the pitch specifying unit and the in-pitch position specified by the in-pitch position specifying unit. When,
Based on the parameters acquired by the parameter acquisition unit, an error correction value calculation unit that calculates an error correction value of the position within the pitch specified by the position determination unit within the pitch, and
A position data correction unit that corrects the position data generated by the position data generation unit based on the error correction value calculated by the error correction value calculation unit;
An encoder is provided.

Moreover, in order to solve the said subject, according to another viewpoint of this invention, the motor which moves a moving body,
A control device for controlling the motor based on position data representing the position of the moving body;
An encoder that detects a position of the moving body, corrects an error included in position data representing the position, and outputs the error to the control device;
Have
The encoder is
A detection signal acquisition unit that acquires at least a detection signal whose amplitude fluctuates by one period every time the moving body moves by one pitch;
Based on the detection signal acquired by the detection signal acquisition unit, a position data generation unit that generates position data representing the position of the moving body;
Based on the position data generated by the position data generation unit, a pitch specifying unit that specifies the pitch at which the moving body is located;
Based on the position data generated by the position data generation unit, an in-pitch position specifying unit that specifies an in-pitch position where the moving body is located;
When a position in the pitch is inputted, a linear error function parameter for deriving an error correction value at the position in the pitch is recorded in advance for each of a plurality of sections set for the pitch, and
A parameter acquisition unit that acquires, from the memory, the parameter corresponding to the section in which the moving body is located based on the pitch specified by the pitch specifying unit and the in-pitch position specified by the in-pitch position specifying unit. When,
Based on the parameters acquired by the parameter acquisition unit, an error correction value calculation unit that calculates an error correction value of the position within the pitch specified by the position determination unit within the pitch, and
A position data correction unit that corrects the position data generated by the position data generation unit based on the error correction value calculated by the error correction value calculation unit;
A motor system is provided.

In order to solve the above problem, according to another aspect of the present invention, the position of the moving body generated based on a detection signal whose amplitude fluctuates by one period every time the moving body moves by one pitch is determined. A pitch specifying step for specifying the pitch at which the moving body is positioned based on the position data to be represented;
Based on the position data, an in-pitch position specifying step for specifying an in-pitch position where the moving body is located;
When the in-pitch position is input, a linear error function parameter for deriving an error correction value at the in-pitch position is stored in the pitch specification from a memory previously recorded for each of the plurality of sections set for each of the pitches. A parameter acquisition step for acquiring the parameter corresponding to the section in which the moving body is located based on the pitch specified in the step and the position in the pitch specified in the position in pitch position specifying step;
Based on the parameters acquired in the parameter acquisition step, an error correction value calculation step for calculating an error correction value of the position in the pitch specified in the position determination step in the pitch,
A position data correction step for correcting the position data generated by the position data generation step based on the error correction value calculated in the error correction value calculation step;
A position data correction method is provided.

  As described above, according to the present invention, errors can be corrected more easily and appropriately.

It is explanatory drawing for demonstrating the structure of the motor system which concerns on 1st Embodiment of this invention. It is explanatory drawing for demonstrating the structure of the encoder and position data correction apparatus which concern on the same embodiment. It is explanatory drawing for demonstrating the correction process of the position data correction apparatus which concerns on the same embodiment. It is explanatory drawing for demonstrating the correction process of the position data correction apparatus which concerns on the same embodiment. It is explanatory drawing for demonstrating the correction process of the position data correction apparatus which concerns on the same embodiment. It is explanatory drawing for demonstrating the correction process of the position data correction apparatus which concerns on the same embodiment. It is explanatory drawing for demonstrating the correction process of the position data correction apparatus which concerns on the same embodiment. It is explanatory drawing for demonstrating operation | movement of the position data correction apparatus which concerns on the same embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same function are denoted by the same reference numerals in principle, and redundant description of these components will be omitted as appropriate.

In the following, for convenience of explanation, the position data correction apparatus according to each embodiment is applied to an encoder, and the encoder is described as an example of an optical rotary type. However, the encoder to which the position data correction apparatus according to each embodiment of the present invention is applied is, for example, a magnetic type, as long as it can obtain a detection signal that periodically changes every time the moving body moves one pitch. Various detection principles may be used. Needless to say, this encoder may be a linear type or a multi-axis type as well as a rotary type as long as such a detection signal can be obtained.
In the following, for the sake of convenience of explanation, an example in which the encoder according to each embodiment is applied to a motor system and the encoder detects the rotational position of the motor system will be described. However, as described above, the encoder according to each embodiment may be applied to a rotary motor system, and can be applied to various objects as long as the position of the moving body moves. Needless to say.

<First Embodiment>
(Motor system)
First, a motor system according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is an explanatory diagram for explaining the configuration of the motor system according to the first embodiment of the present invention.

  As shown in FIG. 1, the motor system 1 according to this embodiment includes a motor 20, an encoder 10, and a control device 30.

  The motor 20 is an example of a power generation source that does not include the encoder 10. The motor 20 has a rotating shaft 21 on at least one side, and outputs a rotational force by rotating the rotating shaft 21 around the rotation axis AX.

  The motor 20 is not particularly limited as long as it is a servo motor controlled based on position data. The motor 20 is not limited to an electric motor that uses electricity as a power source. For example, the motor 20 is a motor using another power source such as a hydraulic motor, an air motor, or a steam motor. There may be. However, for convenience of explanation, a case where the motor 20 is an electric motor will be described below.

  The encoder 10 is disposed on the opposite side of the rotating shaft 21 of the motor 20 and is connected to another rotating shaft 22 that rotates corresponding to the rotating shaft 21. The encoder 10 detects the position of the rotating shaft 22 to detect the position x (rotation angle θ, also referred to as the position x of the motor 20) of the rotating shaft 21 from which the rotational force is output. The position data representing the position x is output.

  The arrangement position of the encoder 10 is not particularly limited. For example, the encoder 10 may be arranged so as to be directly connected to the rotating shaft 21, or connected to a rotating body such as the rotating shaft 21 via another mechanism such as a speed reducer or a rotation direction changer. Also good.

  The control device 30 acquires the position data output from the encoder 10 and controls the rotation of the motor 20 based on the position data. Therefore, in this embodiment in which an electric motor unit is used as the motor 20, the control device 30 controls the rotation of the motor 20 by controlling the current or voltage applied to the motor 20 based on the position data. To do. Further, the control device 30 acquires a high-order control signal from a high-order control device (not shown), and the position or speed represented by the high-order control signal is output from the rotating shaft 11 of the motor 20. It is also possible to control the motor 20. In addition, when the motor 20 uses other power sources, such as a hydraulic type, an air type, and a steam type, the control apparatus 30 controls rotation of the motor 20 by controlling supply of those power sources. Is possible.

(Encoder)
Next, the encoder according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is an explanatory diagram for explaining the encoder according to the first embodiment of the present invention.

  As shown in FIG. 2, the encoder 10 according to the present embodiment broadly includes a detection signal acquisition unit 11, a position data generation unit 12, and a position data correction device 100.

  The detection signal acquisition unit 11 acquires a detection signal whose amplitude fluctuates by one period every time the moving body (shaft 21 in this embodiment) driven by the motor 20 moves by one pitch. In this embodiment, since an optical rotary encoder is used as an example, for example, a rotating disk (not shown) having at least a plurality of slits on a track is attached to the shaft 21 which is a moving body. And the detection signal acquisition part 11 has a light source and a light-receiving part (not shown), irradiates light to a rotating disk from a light source, and receives a reflected signal or transmitted light of a slit in a light-receiving part, and a detection signal is received. Output. As a result, this detection signal becomes a pseudo sine wave signal whose amplitude changes by one cycle each time the rotating disk moves (every 360 ° in electrical angle) by one pitch which is the slit arrangement interval. .

  In the present embodiment, the position data generation unit 12 described later specifies the absolute position of the moving object. On the other hand, the periodic detection signal detected from the above configuration corresponds to an incremental signal. Therefore, the detection signal acquisition unit 11 acquires an absolute position detection signal or an origin detection signal that is processed together with this incremental signal or that is processed separately. Therefore, the detection signal acquisition unit 11 further includes an absolute position detection mechanism or an origin detection mechanism (not shown).

  When the absolute position detection signal is used, the absolute position detection mechanism may be, for example, a 1X (absolute) detection mechanism such as a magnetic type, an optical type, or a resolver type. In the case of a magnetic 1X detection mechanism, for example, a magnet (not shown) is arranged at the center of the rotating disk so that the magnetic pole is located in the plane of the disk, and a fixed magnetic sensor is used to rotate the rotating disk. By detecting the direction of the magnet that changes accordingly, an absolute position detection signal can be obtained.

  When an origin detection signal is used, the origin detection mechanism may be an origin detection mechanism such as a magnetic type, an optical type, or a resolver type. In the case of an optical origin detection mechanism, for example, at least one slit is formed on the rotating disk for the origin, and a light emitting part and a light receiving part are separately provided for the slit, and the light receiving part is reflected or transmitted from the slit. By receiving the light, an origin detection signal can be generated.

  Hereinafter, a case where the detection signal acquisition unit acquires the absolute position detection mechanism will be described as an example. At this time, the absolute position detection mechanism and the absolute position detection signal are referred to as an absolute detection mechanism and an absolute detection signal. In contrast, the detection mechanism and the incremental signal for acquiring the incremental signal are referred to as an incremental detection mechanism and an incremental detection signal. The simple detection signal mainly means an incremental detection signal.

  The position data generation unit 12 acquires an absolute detection signal that changes by one cycle per rotation, and an incremental detection signal whose amplitude changes by one cycle each time the rotating shaft 21 (an example of a moving body) moves by one pitch, Based on both signals, position data representing the position x (absolute position) of the moving body is generated. The position data generation process is not particularly limited. For example, the position data may be generated by the following processing. That is, first, the position data generation unit 12 performs analog / digital conversion on the analog sinusoidal absolute detection signal and the incremental detection signal. Then, the position data generation unit 12 specifies a rough position x from the digitized absolute detection signal (for example, upper bits of the position data). On the other hand, the position data generation unit 12 specifies a finer position x in the rough position x from the digitized incremental detection signal (for example, lower bits of the position data). Then, the position data generation unit 12 synthesizes the rough position x and the fine position x, calculates the absolute position x of the moving body having a resolution comparable to the resolution of the incremental detection signal, and calculates the absolute position Position data representing x is generated.

  In addition, when using the origin detection signal, the position data generation unit 12 specifies the approximate position x by counting the incremental detection signal acquired from the origin detection signal acquisition time, for example. It is possible to generate data.

  The position data correction device 100 acquires the position data generated by the position data generation unit 12, corrects noise (error) included in the incremental detection signal, and converts the position data in which the influence of the noise is reduced, Output to the control unit 30. Here, the noise corrected by the position data correction apparatus 100 can correct a position error including not only a sine wave component changing in a sine wave shape within a pitch but also a non-sine wave component. The position data correction apparatus 100 that realizes such correction will be described in detail later.

(Position error including non-sinusoidal component)
Here, before describing the position data correction apparatus 100, the position error including a non-sinusoidal component will be described with reference to FIGS. 3 and 4 so that the error correction effect by the position data correction apparatus 100 becomes clear. explain. 3 and 4 are explanatory diagrams for explaining the correction processing of the position data correction apparatus according to the present embodiment. 3 and 4, the actual position x0 is represented on the horizontal axis. In FIG. 3, the position x before correction represented in the position data is represented on the vertical axis, and in FIG. 4, the error Δx included in the position x is represented.

  If a position error is not included in the position data regardless of whether it is a sine wave component or a non-sinusoidal wave component, the actual position x0 matches the position x of the position data. It will change on the linear line L0 shown in FIG. However, in actuality, since the incremental detection signal includes a detection error, the position data includes a positional error of a sine wave component and a non-sine wave component. As schematically shown in FIG. With respect to the change of x0, it changes on L1 shifted from the line L0.

  An example of a change with respect to the position x0 in the error Δx with respect to the actual position x0 included in x of the position data is shown in FIG. As shown in FIG. 4, the error Δx at the (n + 1) th pitch (pitch n + 1) does not include a non-sinusoidal component, and thus changes in a sine wave shape within the pitch. On the other hand, the position error Δx at the nth pitch (pitch n) or the first pitch (pitch 1) includes not only a sine wave component but also a non-sine wave component.

  In general, the detection error included in the incremental detection signal that generates the sine wave component included in the position error Δx is caused by the offset due to the irradiation position difference of the light irradiated to the rotating disk or the amplitude difference due to the light amount difference. Often occurs. On the other hand, a detection error included in an incremental detection signal that generates a non-sinusoidal component is often caused by stray light such as reflected light from other members or external light.

  Since the position error Δx is directly included in the position data and affects the control of the motor 20 by the control device 30, it is desirable to reduce the position error Δx regardless of the sine wave component and the non-sine wave component. In the following, for convenience of explanation, the position data correction apparatus 100 capable of correcting such a non-sinusoidal component will be described using a pitch n in which the non-sinusoidal component is included in the position error Δx as an example.

(Position data correction device)
As shown in FIG. 2, the position data correction apparatus 100 includes a pitch specifying unit 101, an in-pitch position specifying unit 102, a memory 103, a parameter acquisition unit 104, an error correction value calculation unit 105, a filter 106, A position data correction unit 107.

  The pitch specifying unit 101 acquires the position data generated by the position data generating unit 12. Then, the pitch specifying unit 101 specifies which pitch among the plurality of pitches the position of the moving body at the time when the incremental detection signal or the like is acquired (hereinafter referred to as detection time). That is, here, for example, based on the position data, the pitch specifying unit 101 has a pitch n (nth pitch) as the position of the moving body at the time of detection among a plurality of pitches shown in FIGS. 3 and 4. Identify that.

  For example, when the data representing the pitch of the position data is represented by 2 bits, the pitch specifying unit 101 uses 0 (00 in binary notation) of the most significant bit of the position data generated by the position data generating unit 12. 4 pitches of 1 (01 in binary notation), 2 (10 in binary notation), 3 (11 in binary notation) are recognized, and the pitch of the position of the moving object is recognized. The recognized data n is notified to the in-pitch position specifying unit 102, the parameter acquiring unit 104, and the filter 106.

  Similarly, the in-pitch position specifying unit 102 acquires the position data generated by the position data generating unit 12. Then, the in-pitch position specifying unit 102 specifies the position of the moving body at the time of detection within the pitch n specified by the pitch specifying unit 101 based on the position data. The position in the pitch is also referred to as an electrical angle (0 to 360 °) or the like, but is referred to herein as an in-pitch position φ (also referred to as an in-pitch position φn for the pitch n). In other words, the absolute position of the moving object represented in the position data can be represented by the pitch n specified by the pitch specifying unit 101 and the in-pitch position φn specified by the in-pitch position specifying unit 102.

  This in-pitch position specifying unit 102 will be described more specifically. For example, when data representing the position in the pitch of the position data is represented by 8 bits, the in-pitch position specifying unit 102 divides one pitch into 256 parts. The parameter acquisition unit 104, the error correction calculation unit 105, and the filter 106 are notified.

  The memory 103 records parameters of an error function for calculating an error correction value Δy for correcting the position error. The error function in the present embodiment is a linear function, unlike the Fourier transform and power series. Accordingly, the parameters include, for example, at least a linear function constant (a, b). On the other hand, the error function according to the present embodiment is set not only for each pitch n but also for each of a plurality of sections (for example, sections n1 to n4) set within each pitch n. The Therefore, the parameter of the error function is recorded in advance in the memory 103 for each of a plurality of sections set for each pitch.

  Here, the correction function and its parameters according to the present embodiment will be described more specifically with reference to FIG. FIG. 5 is an explanatory diagram for explaining the correction processing of the position data correction apparatus according to the present embodiment. FIG. 5 schematically shows only the pitch n shown in FIG. 4 as an example of the pitch.

  As shown in FIG. 5, in this embodiment, four sections n1 to n4 are set for the pitch n. These four sections n1 to n4 can be represented by, for example, the value of the in-pitch position φ. That is, the section n1 of the present embodiment is designated by “0 ° <φ ≦ φn1”, the section n2 is designated by “φn1 <φ ≦ φn2”, the section n3 is designated by “φn2 <φ ≦ φn3”, and the section n4 is designated by “φn3 <φ ≦ 360 °”. That is, the sections n1 to n4 are set by the section break positions φn1 to φn3. The sections n1 to n4 may be set at regular intervals similarly to the zero cross points of the sine wave, but the sections n1 to n4 according to the present embodiment can be set at other than regular intervals. That is, it can be said that the lengths of the sections n1 to n4 are set in the parameters by including the partition positions φn1 to φn3 in the parameters in the sections n1 to n4. Note that the lengths of the sections n1 to n4 may be set directly instead of the partition positions φn1 to φn3. In this case, the lengths of the sections n1 to n4 are all one pitch long. It is set so as not to exceed (360 °).

  On the other hand, the correction function constants (an1, bn1) to (an4 to bn4) expressed as linear functions are recorded in the memory 103 as parameters for each of the sections n1 to n4. The correction function is expressed by the following formula (1).

  These parameters can be set as follows using, for example, an error measuring device (not shown). That is, first, a reference encoder or the like is attached to the encoder 10, and position data representing the position x before correction or not corrected correctly is recorded in the memory or the like of the error measuring device. On the other hand, the actual accurate position x0 output from the reference encoder is recorded in the memory or the like of the error measuring device. Then, the error measuring device subtracts both and records the result (that is, the position error Δx) in a memory or the like. Further, the error measuring device specifies the pitch n and the in-pitch position φn from the position x used for subtraction, and records it in the memory or the like in association with the subtraction result. Such processing is performed a plurality of times for each pitch. Based on the data recorded in the memory or the like, the error measuring device can detect the position error Δx that can include not only a sine wave component as shown in FIG. 5 but also a non-sine wave component for each pitch n. Profile data for the in-pitch position φn is generated.

  Thereafter, for each profile data of each pitch n, the error measuring device specifies the zero cross point, the maximum point, and the minimum point in the profile by the in-pitch position φ, and specifies a plurality of specified in-pitch positions φ (4 or more). Is recorded in a memory or the like in association with the pitch n as a parameter for setting the sections n1 to n4. Then, the error measuring device obtains a linear function passing through two points from two adjacent points among the zero cross point, the maximum point, and the minimum point and the position error Δx with respect to the point, and a constant ((an1, bn1) and the like) are recorded in a memory or the like in association with each of the sections n1 to n4. Thereafter, the error measuring apparatus records the data recorded in the memory or the like in the memory 103 of the position data correcting apparatus 100 as a parameter representing the correction function.

  By performing such an operation over the entire measurement range of the encoder 10 (that is, one rotation of the disk), the memory 103 has error function parameters that can calculate the error correction value Δy shown in FIG. They are set in association with each other as shown in Table 1.

  Thus, in the present embodiment, four or more sections n1 to n4 are set for each pitch n by the above parameters. And the parameter of a linear function is set with respect to each area n1-n4. As a result, as shown in FIG. 5, the change of the error correction value Δy by the linear error function becomes a triangular wave shape of 2 or more within the pitch n of 1. Since the position data correction apparatus 100 according to the present embodiment can set parameters for each of the sections n1 to n4 as described above, a plurality of triangular waves representing changes in the error correction value Δy are as shown in FIG. It is possible to have different widths or extreme values with different absolute values.

  Based on the pitch n specified by the pitch specifying unit 101 and the in-pitch position φ specified by the in-pitch position specifying unit, the parameter acquisition unit 104 is a section ni (i = 1, 2, 3,...) Where the moving body is located. ) (Ani, bni) corresponding to) is acquired from the memory 103. Then, the parameter acquisition unit 104 outputs the acquired parameter to the error correction value calculation unit 105.

  The operation of the parameter acquisition unit 104 will be described with a more specific example as follows. For example, with respect to the time point when the detection signal acquisition unit 11 acquires the detection signal, the pitch specifying unit 101 specifies the pitch at which the moving body is positioned as the pitch n, and the in-pitch position specifying unit 102 determines the position within the pitch of the moving body. It is assumed that the position in the pitch φnk (φn1 <φnk <φn2) is specified. Then, the parameter acquisition unit 104 searches for a plurality of parameters that are associated and recorded in the memory 103 as shown in Table 1 above, and specifies parameters corresponding to the pitch n and the in-pitch position φnk. That is, in this case, the parameter acquisition unit 104 extracts a parameter associated with the pitch n based on the pitch n, and specifies a section n2 including the in-pitch position φnk from information regarding the extracted parameter section. . Then, the parameter acquisition unit 104 acquires the parameters (an2, bn2) associated with the identified pitch n and section n2, and outputs them to the error correction value calculation unit 104.

  The error correction value calculation unit 105 acquires the parameters (for example, (an2, bn2)) output by the parameter acquisition unit 104, and further acquires the in-pitch position φnk specified by the in-pitch position specifying unit 102. Then, the error correction value calculation unit 105 calculates an error correction value Δy by substituting the parameter into the above equation (1) to derive an error function and substituting the in-pitch position φnk as a variable into the derived error function. To do.

  The filter 106 acquires the pitch n specified by the pitch specifying unit and the in-pitch position φnk specified by the in-pitch position specifying unit. Then, the filter 106 filters the error correction value Δy calculated by the error correction value calculation unit 105 based on the acquired pitch n and in-pitch position φnk, and outputs it to the position data correction unit 107.

  Various types of filtering can be used for the filtering performed here. For example, the filter 106 outputs to the position data correction unit 107 only an error correction value Δy of a certain value or more in an arbitrary range, outputs only a positive or negative error correction value Δy, or out of the range. For example, only the error correction value Δy is output. The set values such as the type of filtering and the threshold value / range used for the filtering are, for example, the error Δx measured in advance, the error function, the characteristics of the position data correction device 100, the encoder 10, and the motor 20, and the like. Accordingly, it is possible to set in advance, such as user settings and adjustments during manufacturing. By performing such filtering, not only based on the error correction value Δy based on the error function measured in advance, but also fine correction according to the error function and the characteristics of the device itself is performed for each pitch. This makes it possible to perform error correction more easily and appropriately. For example, when correction is not necessary within a predetermined pitch, if the filter 106 is used, easy and fine correction can be performed for each pitch.

  In addition, it is desirable that the arbitrary range in which the above filtering is performed is set to 1 or 2 or more for each pitch in order to perform error correction for each pitch more appropriately. More specific operations in the filter 106 will be described together with the position data correction unit 107 by giving an example.

  The position data correction unit 107 corrects the position data (position x) generated by the position data generation unit 12 based on the error correction value Δy calculated by the error correction value calculation unit 105. That is, the position data correction unit 107 subtracts the error correction value Δy from the position x represented in the position data (addition may be performed depending on the sign), thereby not only the sine wave component but also the non-sine wave. Position data with reduced component errors is also generated. The corrected position data is output to the control unit 30. However, in this embodiment, since the position data correction unit 107 acquires the error correction value Δy via the filter 106, the acquired error correction value Δy is a value after filtering.

  Here, the correction processing in the filter 106 and the position data correction unit 107 will be described with reference to FIGS. 6 and 7 and more specific examples of filtering. 6 and 7 are explanatory diagrams for explaining the correction processing of the position data correction apparatus according to the present embodiment.

  FIG. 6 exemplifies filtering in which the ranges Fn1 to Fn3 in which filtering is performed are preset with respect to the pitch n, and the error correction value Δy is not output from the filter 106 in that range. That is, as shown in FIG. 6, in the filter 106, ranges Fn1 to Fn3 in which filtering is performed at each pitch n are specified by the in-pitch position φn and set in advance. Then, when the filter 106 acquires the pitch n and the in-pitch position φn, whether or not filtering is performed based on the pitch n and the in-pitch position φn (in some cases, includes the type of filtering). ). Thereafter, when the in-pitch position φn is included in the ranges Fn1 to Fn3 to be filtered, the filter 106 does not output the error correction value Δy to the position data correction unit 107 as an example of filtering, and does not include it. Outputs the error correction value Δy to the position data correction unit 107.

  Then, the position data correction unit 107 acquires the error correction value Δy for the in-pitch positions φn other than the ranges Fn1 to Fn3 shown in FIG. 6, and corrects the position x represented by the position data with the acquired error correction value Δy. To do. The error Δx included in the corrected position x is shown in FIG. As shown in FIG. 7, the error Δx remains uncorrected in the sections of the ranges Fn1, Fn2, and Fn3, and the error Δx included in the position x is corrected outside the ranges Fn1 to Fn3. For example, when the error Δx included in the position x is 0 in the sections of the ranges Fn1, Fn2, and Fn3, the filter 106 provides a new correction function (other than Equation 1) for the error Δx included in the position x within the pitch n. Correction is possible without any problem. Further, not only the position error of the sine wave component but also the position error of the non-sine wave component can be corrected without providing a new correction function (other than Equation 1). Further, it is possible to correct an error Δx that occurs locally within the pitch n.

(Operation of position data correction device)
Next, the operation of the position data correction apparatus according to the first embodiment of the present invention will be described with reference to FIG. FIG. 8 is an explanatory diagram for explaining the operation of the position data correction apparatus according to the first embodiment of the present invention.

  First, when the motor 20 moves the moving body, the detection signal acquisition unit 11 acquires a detection signal. Then, the detection signal is sent to the position data generation unit 12, and the position data generation unit 12 generates position data representing the position x (absolute position) based on the detection signal. Then, the position data correction apparatus 100 processes step S01 shown in FIG.

  In step S01 (an example of a pitch specifying step), the pitch specifying unit 101 specifies the pitch n where the moving body is located based on the position data. Next, step S03 is processed.

  In step S03 (an example of an in-pitch position specifying step), the in-pitch position specifying unit 102 determines an in-pitch position φn (0 to 360 °) at the pitch n based on the pitch n specified in step S01 and the position data. ). After step S03, the process proceeds to step S05.

  In step S05 (an example of a parameter acquisition step), the parameter acquisition unit 104 searches the memory 103 based on the pitch n and the in-pitch position φn, and associates the pitch n with the in-pitch position φn. The parameter (ani, bni) of the section ni is acquired. Then, the parameter acquisition unit 104 outputs the acquired parameter to the error correction value calculation unit 105. Then, step S06 is processed.

  In step S07 (an example of an error correction value calculation step), the error correction value calculation unit 105 derives an error function based on the parameters acquired in step S05, and an error is calculated from the error function and the in-pitch position φn. A correction value Δy is calculated. Then, the process proceeds to step S09.

  In step S09 (an example of a filtering step), the filter 106 specifies the type of filtering and whether or not to perform filtering based on a preset setting value. When the in-pitch position φn is included in the filtering range Fn1 to Fn3, the filter 106 performs filtering according to the specified type (for example, shielding of the error correction value Δy) on the error correction value Δy. . On the other hand, when the in-pitch position φn is not included in the range, the filter 106 outputs the error correction value Δy to the position data correction unit 107 without performing filtering. Step S11 is processed after step S09.

  In step S11 (an example of a position data correction step), the position data correction unit 107 subtracts the error correction value Δy after the process in step S09 from the position x generated from the position data generation unit 12 to obtain an error. The position data representing the position x corrected for is output to the control unit 30. Note that, depending on the type of filtering, the position data correction unit 107 generates position data representing the position x without subtracting the error correction value Δy. It shall be included in a kind of amendment. After the process of step S11, a series of correction operations by the position data correction device ends, but for example, the above-described steps S01 to S11 are repeated each time the motor 20 rotates or at a predetermined period. become.

(Example of effects according to this embodiment)
The position data correction device, encoder, motor system, and position data correction method according to the first embodiment of the present invention have been described above.
According to the position data correction apparatus and the like according to the present embodiment, since the error function can be changed for each of a plurality of sections set in the pitch, not only the error (noise) of the sine wave component, Thus, it is possible to perform error correction more appropriately for errors of non-sinusoidal components. At this time, the error function for each section is represented by a linear function, and the parameters of the linear function are recorded in the memory 103 for each pitch, so that the amount of recorded data is reduced and the error correction value is calculated. The error of the non-sinusoidal component can be corrected without increasing the amount of processing at the time. Therefore, it is possible to perform the appropriate correction as described above very easily.

  Further, according to this position data correction device or the like, the parameters are set so that four or more sections are set for one pitch, and the profile of the error function based on the parameters for each section has a triangular wave shape of two or more. Is set. In addition, the absolute values of two or more extreme values of the triangular wave shape error correction value are set to be different from each other. The parameter also includes information on the length of each section. Accordingly, the height and inclination of the extreme value of the triangular wave shape can be set more finely, and appropriate error correction can be performed without greatly increasing the amount of data or calculation.

  Further, according to this position data correction device or the like, the filter 107 performs position correction using the error correction value Δy derived from the error function as it is within an arbitrary range, or error correction subjected to arbitrary filtering processing. It is possible to switch between position corrections using the value Δy. The type of filtering process, the threshold value, and the like can be switched within an arbitrary range. Therefore, it is possible to appropriately correct the error Δx included in the position x. In addition, the error Δx that occurs locally due to external light, reflected light from other parts, stray light, or the like can be similarly appropriately corrected.

  The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, it goes without saying that the present invention is not limited to the examples of these embodiments. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can make various changes and modifications within the scope of the technical idea described in the claims. Accordingly, the technology after these changes and corrections naturally belong to the technical scope of the present invention.

  For example, although the case where the position data correction apparatus 100 includes the filter 106 has been described in the above embodiment, the present invention is not limited to such an example. For example, when the filtering process by the filter 106 is not necessary, the position data correction apparatus 100 may not have the filter 106, or the filter 106 may be set not to perform the filtering process in the entire range. is there. Further, the filter 106 can perform a filtering process corresponding to all the pitches, and can also perform a filtering process only for a predetermined pitch.

In this specification, the steps described in the flowcharts are executed in parallel or individually even if they are not necessarily processed in time series, as well as processes performed in time series in the described order. Including processing to be performed. Further, it goes without saying that the order can be appropriately changed even in the steps processed in time series.

DESCRIPTION OF SYMBOLS 1 Motor system 10 Encoder 11 Detection signal acquisition part 12 Position data generation part 20 Motor 21, 22 Rotation shaft 30 Control apparatus 100 Encoder 101 Pitch specification part 102 In-pitch position specification part 103 Memory 104 Parameter acquisition part 105 Error correction value calculation part 106 Filter 107 Position data correction section x Position Δx error Δy Error correction value φ Position in pitch n Pitch

Claims (7)

Pitch specification that specifies the pitch at which the moving body is located based on position data that represents the position of the moving body that is generated based on a detection signal whose amplitude varies by one period each time the moving body moves by one pitch. And
Based on the position data, an in-pitch position specifying unit that specifies an in-pitch position where the moving body is located;
A memory in which a linear error function parameter for deriving an error correction value at the in-pitch position when the in-pitch position is input is recorded in advance for each of a plurality of sections set for each of the pitches;
A parameter acquisition unit that acquires, from the memory, the parameter corresponding to the section in which the moving body is located based on the pitch specified by the pitch specifying unit and the in-pitch position specified by the in-pitch position specifying unit. When,
Based on the parameters acquired by the parameter acquisition unit, an error correction value calculation unit that calculates an error correction value of the position in the pitch specified by the position specification unit in the pitch;
A position data correction unit that corrects the position data generated by the position data generation unit based on the error correction value calculated by the error correction value calculation unit;
A position data correction device. The parameter is set for each of the four or more sections for each of the pitches so that a change in an error correction value by the linear error function becomes a triangular wave shape of two or more within the one pitch.
2. The position data correction device according to claim 1, wherein the parameter in at least one or more of the pitches is set such that absolute values of two or more extreme values in the two or more triangular wave shape error correction values are different from each other. .   The position data correction device according to claim 2, wherein the parameter includes a length of each section in the pitch.   Based on the pitch specified by the pitch specifying unit and the in-pitch position specified by the in-pitch position specifying unit, the error correction value calculated by the error correction value calculating unit is filtered to the position data correcting unit. The position data correction apparatus according to claim 1, further comprising a filter for outputting. A detection signal acquisition unit that acquires at least a detection signal whose amplitude fluctuates by one period every time the moving body moves by one pitch;
Based on the detection signal acquired by the detection signal acquisition unit, a position data generation unit that generates position data representing the position of the moving body;
Based on the position data generated by the position data generation unit, a pitch specifying unit that specifies the pitch at which the moving body is located;
Based on the position data generated by the position data generation unit, an in-pitch position specifying unit that specifies an in-pitch position where the moving body is located;
A memory in which a linear error function parameter for deriving an error correction value at the in-pitch position when the in-pitch position is input is recorded in advance for each of a plurality of sections set for each of the pitches;
A parameter acquisition unit that acquires, from the memory, the parameter corresponding to the section in which the moving body is located based on the pitch specified by the pitch specifying unit and the in-pitch position specified by the in-pitch position specifying unit. When,
Based on the parameters acquired by the parameter acquisition unit, an error correction value calculation unit that calculates an error correction value of the position in the pitch specified by the position specification unit in the pitch;
A position data correction unit that corrects the position data generated by the position data generation unit based on the error correction value calculated by the error correction value calculation unit;
Having an encoder. A motor that moves the moving body;
A control device for controlling the motor based on position data representing the position of the moving body;
An encoder that detects the position of the moving body, corrects an error included in position data representing the position, and outputs the error to the control device;
Have
The encoder is
A detection signal acquisition unit that acquires at least a detection signal whose amplitude fluctuates by one period every time the moving body moves by one pitch;
Based on the detection signal acquired by the detection signal acquisition unit, a position data generation unit that generates position data representing the position of the moving body;
Based on the position data generated by the position data generation unit, a pitch specifying unit that specifies the pitch at which the moving body is located;
Based on the position data generated by the position data generation unit, an in-pitch position specifying unit that specifies an in-pitch position where the moving body is located;
A memory in which a linear error function parameter for deriving an error correction value at the in-pitch position when the in-pitch position is input is recorded in advance for each of a plurality of sections set for each of the pitches;
A parameter acquisition unit that acquires, from the memory, the parameter corresponding to the section in which the moving body is located based on the pitch specified by the pitch specifying unit and the in-pitch position specified by the in-pitch position specifying unit. When,
Based on the parameters acquired by the parameter acquisition unit, an error correction value calculation unit that calculates an error correction value of the position in the pitch specified by the position specification unit in the pitch;
A position data correction unit that corrects the position data generated by the position data generation unit based on the error correction value calculated by the error correction value calculation unit;
Having a motor system. Pitch specification that specifies the pitch at which the moving body is located based on position data that represents the position of the moving body that is generated based on a detection signal whose amplitude varies by one period each time the moving body moves by one pitch. Steps,
An in-pitch position specifying step for specifying an in-pitch position where the movable body is located based on the position data;
When the in-pitch position is input, a linear error function parameter for deriving an error correction value at the in-pitch position is stored in the pitch specification from a memory recorded in advance for each of a plurality of sections set for each pitch. A parameter acquisition step for acquiring the parameter corresponding to the section in which the moving body is located based on the pitch specified in the step and the position in the pitch specified in the position in pitch position specifying step;
Based on the parameter acquired in the parameter acquisition step, an error correction value calculation step of calculating an error correction value of the position in the pitch specified in the position determination step in the pitch;
A position data correction step for correcting the position data generated by the position data generation step based on the error correction value calculated in the error correction value calculation step;
A position data correction method.