JP2007187591A - Encoder device and method of measuring disk concentricity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encoder device and an eccentricity measuring method capable of determining precise eccentricity with a simple calculation. <P>SOLUTION: In step 1, the power source of an encoder device is turned to ON, and in step 2, a rotary disk not shown is rotated at a fixed speed. In step 3, an eccentricity measuring command is transmitted from a higher-level device not shown. In step 4, a time required for counting P/2 pulses, namely, a pulse number for a half rotation of the rotary disk (not shown) is measured and in step 5, eccentricity is calculated and stored. In step 6, whether operations are executed predetermined times is checked. In step 7, a maximum value of the eccentricity stored in step 5 is extracted; in step 8, whether the value is within a reference value; and in step 9, an OK signal when it is within the reference value or an NG signal when it exceeds the value is transmitted the higher-level device (not shown). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an encoder device that detects the rotational position of a rotating body such as a servo motor, and more particularly to an encoder device having a function for measuring eccentricity of a rotating disk and a method for measuring the disk concentricity thereof.

  Conventionally, detection error data resulting from the eccentricity or attachment error of the detected object in the position detector attached to the rotating shaft is calculated based on the output signal from the position detector attached to the rotating shaft, and is stored in the position control device. The detection error data is corrected for the rotation command position for the motor that drives the rotating shaft to obtain the rotation command position for the motor. A position control device that cancels a detection error caused by the above has been disclosed (see, for example, Patent Document 1).

FIG. 7 is a block diagram of a position control apparatus showing a first conventional example.
In the drawing, reference numeral 91 denotes a main shaft of a machine tool or a rotation shaft of a motor. A detected body 92a of the position detector 92 is attached to one end of the rotation shaft 91, and a sensor 92b of the position detector 92 is disposed close to the detected body 92a, and the detected body 92a rotates. The position is detected, and a detection signal is fed back to the position controller 93.
Further, an expensive high-accuracy position detector 94 that can detect the rotational position by removing the influence of eccentricity is attached to the other end of the rotating shaft 91.
A position command is output from the position controller 93, the rotary shaft 91 is positioned, and the difference between the position detected by the high-accuracy position detector 94 and the command position is detected as detection error data due to the eccentricity of the detected object 92a. The detection error data is obtained and set and stored in the memory in the position controller 93.

FIG. 8 is a block diagram of a position control device showing a second conventional example. The high-precision position detector shown in the first conventional example is not used, and detection error data is obtained by its own position detector 92. It is something to remember.
In this conventional example, the rotation axis is rotated at a constant speed using its own position detector 92, and the peak value of the movement amount (speed) for each sampling period is determined from the output signal from the position detector attached to the rotation axis. To calculate the amount of eccentricity.
Japanese Patent Laid-Open No. 11-27973

  In the first conventional example, a high-accuracy position detector is used to detect detection error data due to the eccentricity of the detected object 2a of the position detection device. There is a problem that a large-scale measuring facility is required and a process for replacing the facility is also required.

In the second conventional example, since the amount of eccentricity is obtained from the peak value of the movement amount (speed) for each sampling period detected from the position detection device attached to the rotation shaft, the high speed for obtaining the speed is obtained. Complex processing was necessary. In addition, when the rotating shaft has a speed ripple, there is a problem that the amount of eccentricity cannot be obtained with high accuracy.
The present invention has been made in view of such problems, and an encoder apparatus and an eccentricity measuring method thereof that can accurately determine the eccentricity with a simple calculation without requiring a large-scale measurement facility. The purpose is to provide.

In order to solve the above-mentioned problem, the invention according to claim 1 is directed to detecting a rotating disk attached to a rotating body and a two-phase signal having a phase difference of 90 degrees according to the rotation of the rotating disk. And an encoder device comprising: a microcomputer that converts an output signal from the detection unit into rotational position information; and a transmission circuit unit that transmits the rotational position information to a host device. A concentricity calculating unit for calculating the eccentricity of the rotating disk is provided.
According to a second aspect of the present invention, the concentricity calculation unit includes a pulse signal conversion unit that converts the output signal into a pulse signal, a pulse count unit that counts the number of pulses of the pulse signal, and the number of pulses. A time measuring unit that measures the time required until the predetermined number of counts is reached, and a determination processing unit that determines whether the concentricity of the rotating disk exceeds a predetermined value from the time measured by the time measuring unit It is characterized by having.
According to a third aspect of the present invention, the time measuring unit measures a time required to count the number of pulses corresponding to a half rotation of the rotating disk when the rotating disk is rotated at a constant speed. It is characterized by that.
According to a fourth aspect of the present invention, there is provided a rotating disk attached to a rotating body, a detecting unit that outputs two-phase signals having a phase difference of 90 degrees according to the rotation of the rotating disk, and the detecting unit In an encoder apparatus comprising a microcomputer that converts the output signal from the rotation position information into a rotation position information and a transmission circuit section that transmits the rotation position information to a host device, the rotation disk is rotated at a constant speed, The output signal is converted into a pulse signal, and the time required to detect the number of pulses corresponding to a predetermined rotation angle of the rotating disk is measured at a plurality of rotational positions of the rotating disk, and a plurality of times obtained by this measurement are measured. The maximum value or minimum value is extracted from the time, and the amount of eccentricity is calculated from the maximum value or minimum value to determine whether the amount of eccentricity exceeds a predetermined value. It is characterized in that.

According to the first aspect of the invention, since the encoder device has a function of calculating the eccentric amount of the rotating disk of the encoder device, there is no need to provide an external measuring means, and the eccentric amount can be measured with a simple configuration. it can.
According to the invention described in claim 2, since the number of pulses corresponding to a predetermined rotation angle is counted and the concentricity is measured from the time required for the counting, there is no need to perform complicated speed calculation, and calculation processing Becomes easier.
According to the third aspect of the present invention, when the rotating disk is rotated at a constant speed, if the number of pulses corresponding to a half rotation of the rotating disk is counted, it is difficult to be affected by the speed ripple, so the eccentricity is accurately measured. it can.
According to the invention described in claim 4, the time required for detecting the number of pulses corresponding to a predetermined rotation angle of the rotating disk by rotating the rotating disk at a constant speed is measured at a plurality of rotating positions of the rotating disk. Since the amount of eccentricity is calculated from the maximum value or the minimum value of a plurality of times obtained by this measurement, the amount of eccentricity can be measured with a simple calculation process.

  Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an encoder apparatus showing a first embodiment of the present invention.
Reference numeral 1 denotes a rotating disk, which has a bright and dark slit pattern formed on its outer periphery, and is fixed to a rotating shaft 6 by a rotating disk fixing jig 7. The rotating shaft 6 is fixed to a rotating shaft of a motor (not shown) that connects the encoder device, and rotates in the same way. In addition, a light emitting element 21 is disposed on one side of the slit pattern of the rotating disk 1 and a light receiving element 22 is disposed at an opposite position.
FIG. 2 is a circuit block diagram of the encoder device of the present invention.
In the figure, reference numeral 4 denotes a signal processing circuit, a position signal calculation unit 41 that converts an output signal from the light receiving element 22 into rotation position information, a concentricity calculation unit 42 that calculates the eccentric amount of the rotating disk, and a serial transmission circuit. The unit 43 is mounted, and the position information is serially transmitted to the host device 8. The position signal calculation unit 41 and the concentricity calculation unit 42 are subjected to calculation processing by the microcomputer 40.

First, the principle of measuring the concentricity according to the present invention will be described with reference to FIG.
FIG. 3 is a schematic diagram showing the principle of measuring the concentricity of the encoder device of the present invention.
In the figure, O is the center of the rotating disk 1, O ′ is the center of rotation of the rotating disk 1, and the distance from the center O of the rotating disk 1 to the center of rotation O ′ is the eccentricity ε. R is the distance from the center of the rotating disk 1 to the detector 2.
S1, S2 and S2 ′ indicate the positions of the slit patterns formed on the rotating disk. In this figure, the slit position S1 is at the position of the detector 2, and S2 and S2 ′ are respectively S1 and O2. , S2 and ∠S1, O ′, S2 ′ indicate the slit positions at points where the angle is 90 degrees. When the rotary disk 1 rotates 90 degrees counterclockwise from the slit position in the figure, the slits from S1 to S2 ′ pass through the detection unit 2. This corresponds to the number of slits corresponding to (90−θe) degrees on the rotating disk.
As described above, when the rotating disk rotates eccentrically, an angular error of one cycle occurs during one rotation, and the angular error θe is θe (pp) ≈ε (pp) / r (1) )
It can be seen that (Pp) represents peak-to-peak.
That is, if the distance r from the center of the rotating disk to the detector 2 and the angle error θe are known, the eccentricity ε can be obtained.
If there is an encoder with P pulses per rotation and it is rotated by N [min ⁻¹ ], if the encoder has zero eccentricity, the number of pulses dp per unit time is
dp = P / (60 / N) [pulse / s] (2)
It can be expressed as

Here, in the encoder whose amount of eccentricity is unknown, if a (P / 2) pulse having the number of pulses corresponding to 1/2 rotation is generated at time T [s], the pulse shift amount dP is 1 from time T. Since the number of pulses dP (= dT × dp) generated in dT (= T−30 / N) minus the time (30 / N) required for / 2 rotations,
dP = (T-30 / N) × (P / (60 / N))
It is represented by
When this is converted into an angle error θe,
θe = 2π × dP / P [rad p−p]
= 2π × (((T / (30 / N)) − 1) × (P / 2)) / P [rad p−p]
From the equation (1), the concentric displacement amount ε is ε = θe × r
= (2π × (((T / (30 / N)) − 1) × (P / 2)) / P) × r
= Π × ((T / (30 / N)) − 1))
It is obtained by.

For example, if there is an encoder with a rotating disk radius = 15 mm and this is rotated at 100 min ⁻¹ and it takes 301 ms to come to P / 2 pulses, the amount of concentric displacement ε≈157 μm from the above calculation.

Next, a concentricity measurement method will be described.
FIG. 4 is a block diagram showing the configuration of the concentricity calculation unit, and FIG. 5 is a flowchart showing the concentricity measuring method.
In FIG. 4, reference numeral 421 denotes a pulse signal conversion unit that converts an output signal from the detection unit into a pulse signal, 422 denotes a pulse count unit that counts the pulse signal, and an output signal of the pulse count unit 422 is a start signal indicating a count start point. The stop signal output at the point where the predetermined count value is reached is output. In this embodiment, a stop signal is output when P / 2 pulses are counted.
Reference numeral 423 denotes a time measurement unit that measures the time from the start signal to the stop signal, and reference numeral 424 denotes a determination processing unit that determines whether the time is within a predetermined time.

In FIG. 5, first, in step 1, the encoder apparatus is turned on, and in step 2, the encoder is rotated at a constant speed by external driving. In step 3, a concentricity measurement command is transmitted from the host. In step 4, the time required for counting P / 2 pulses is measured, and in step 5, the amount of eccentricity is calculated and stored.
In step 6, it is confirmed whether the set number of times has been performed. If the set number of times has not been measured, step 4 and step 5 are repeated until the set number of times.
Thereafter, in step 7, the maximum value of the eccentricity stored in step 5 is extracted. In step 8, it is determined whether or not the maximum value of the eccentricity exceeds the reference value. If so, an OK signal is transmitted to the host device if it exceeds the reference value.
Note that steps 4 and 5 are repeated a plurality of times, depending on the position at which the P / 2 pulse is measured, the eccentricity in the positive and negative directions occurs within the position at which the P / 2 pulse is measured, resulting in an angular error. This is because the amount of change becomes smaller and does not correspond to the amount of eccentricity.

FIG. 6 is a schematic diagram for explaining a method of detecting the amount of eccentricity, and shows that the maximum value of the change in angle error can be detected by a plurality of measurements, whereby the amount of eccentricity can be detected.
6A is a waveform showing the operation of the pulse count unit 422, FIG. 6B is a waveform of a start pulse and a stop pulse, and FIG. 6C is a waveform of an angle error.
As shown in FIG. 6A, the P / 2 pulse and the P / 16 pulse are alternately counted by the pulse counting unit, and as shown in FIG. It is output at the count start point and end point of two pulses. In FIG. 6 (c), T1, T2,... Indicate the time required to count P / 2 pulses at each measurement count, and Td1, Td2,... Indicate the pause time until the next measurement is performed. ing. In this embodiment, the time for executing the count of P / 16 pulses is used. Further, as shown in FIG. 6C, the angle error has a waveform of one cycle per rotation.
In the K-th measurement, the change in the angle error is the largest, and since the change is from the minus error to the plus error, the P / 2 pulse time Tk is minimized at this time.

  As described above, since the measurement is always performed in the vicinity where the maximum value and the minimum value of the time required for counting the P / 2 pulses are generated by shifting the measurement position little by little, the amount of eccentricity can be measured with high accuracy. Further, since the amount of eccentricity is calculated from the P / 2 pulse time, even if a speed ripple occurs due to the influence of the measuring device, it is averaged within the P / 2 pulse time and the influence on the P / 2 pulse time is small.

  In this embodiment, the time required for counting P / 2 pulses was measured to determine the amount of eccentricity. However, when this measurement is set to P / 4, the pulse shift amount dP is half that of the case of P / 2 pulses. Therefore, it is obvious that the same eccentricity result can be obtained by doubling dP.

  As described above, in the present invention, since the concentricity can be confirmed at the time of shipping adjustment, a large-scale dedicated measurement facility is not required, and the accuracy is confirmed without causing a replacement process to the dedicated facility. Will be able to. Further, it is possible to prevent a disc pasting operation error and to prevent a defective product from flowing out due to an incorrect assembly, thereby improving the reliability of a system using an encoder.

The block diagram of the encoder apparatus which shows 1st Example of this invention Circuit block diagram of encoder device of the present invention The schematic diagram which shows the measurement principle of the concentricity of the encoder apparatus of this invention The block diagram which shows the structure of the concentricity calculating part of the encoder apparatus of this invention The flowchart which shows the concentricity measuring method of the encoder apparatus of this invention Schematic diagram for explaining a method of detecting the amount of eccentricity of the encoder device of the present invention Configuration diagram of a position control device showing a first conventional example Configuration diagram of position control device showing second conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotating disk 2 Detection part 21 Light emitting element 22 Light receiving element 3 Fixing jig 4 Signal processing circuit 40 Microcomputer 41 Position signal calculating part 42 Concentricity calculating part 421 Pulse signal converting part 422 Pulse counting part 423 Time measuring part 424 Determination processing part
43 Transmitting circuit unit 5 Bearing 6 Rotating shaft 7 Rotating disk fixing jig 8 Host device

Claims (4)

A rotating disk attached to a rotating body, a detection unit that outputs two-phase signals having a phase difference of 90 degrees according to the rotation of the rotating disk, and an output signal from the detection unit is converted into rotation position information. In an encoder device comprising a microcomputer and a transmission circuit unit for transmitting the rotational position information to a host device,
The said microcomputer was provided with the concentricity calculating part which calculates the eccentricity of the said rotary disk from the said output signal.   The concentricity calculation unit includes a pulse signal conversion unit that converts the output signal into a pulse signal, a pulse count unit that counts the number of pulses of the pulse signal, and a time required for the number of pulses to reach a predetermined count number 2. A time measuring unit for measuring the time, and a determination processing unit for determining whether or not the concentricity of the rotating disk exceeds a predetermined value from the time measured by the time measuring unit. The encoder device described.   3. The encoder according to claim 2, wherein the time measuring unit measures a time required to count the number of pulses corresponding to a half rotation of the rotating disk when the rotating disk is rotated at a constant speed. apparatus. A rotating disk attached to a rotating body, a detection unit that outputs two-phase signals having a phase difference of 90 degrees according to the rotation of the rotating disk, and an output signal from the detection unit is converted into rotation position information. In an encoder device comprising a microcomputer and a transmission circuit unit for transmitting the rotational position information to a host device,
Rotating the rotating disk at a constant speed;
The output signal from the detection unit is converted into a pulse signal,
Measuring the time required to detect the number of pulses corresponding to a predetermined rotation angle of the rotating disk at a plurality of rotating positions of the rotating disk;
A maximum value or a minimum value is extracted from the plurality of times obtained by the measurement;
Calculate the amount of eccentricity from the maximum or minimum value,
A disc concentricity measuring method for an encoder device, wherein it is determined whether or not the amount of eccentricity exceeds a predetermined value.

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