JP2005003672A - Analyzing system for encoder position error - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an analyzing system for encoder position error which can detect offset voltage components, gaps in amplitude ratio, phase shift, secondary voltage components and tertiary voltage components of encoder signal. <P>SOLUTION: The encoder position error analyzing system comprises a 1st DFT (Diagnostic Function Test)/FFT (Fast-Fourier Transform) analyzer 21 providing frequency analysis of a positional error signal waveform 11; a 2nd DFT/FFT analyzer 22 providing frequency analysis of A phase signal waveform 12; and a parameter analyzer 30 detecting error signal component contained in encoder original waveform, based on the phase information of the primary components resulting from both frequency analyses of the position error signal waveform provided by the 1st DFT/FFT analyzer 21 and the A phase signal waveform by the 2nd DFT/FFT analyzer 22. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention locates error factors included in a two-phase encoder analog signal, specifically, an amplitude ratio / phase difference of a two-phase signal, an offset voltage component, a second harmonic component, and a third harmonic component included in the two-phase signal. The present invention relates to an encoder position error analysis device that calculates from an error signal.

As a conventional encoder position error analysis apparatus, an invention has been made in which the time waveform of an encoder signal is A / D converted and taken in, and signal processing is performed by a CPU to detect an offset voltage component, amplitude, and phase difference of the encoder signal ( For example, see Patent Document 1).
FIG. 17 shows a block diagram described in Patent Document 1.
In the figure, reference numeral 201 denotes a numerical control device, and reference numeral 202 denotes a motor control device. The motor control device 202 includes a position control unit 221, a speed control unit 222, a drive circuit 223, detection circuits 224 and 225, a calculation unit 226, a storage unit 227, and a display unit 228. The encoder 205 attached to the rotating shaft of the motor 203 and the encoder 206 attached to the main shaft 204 detect a sine wave analog signal having a 90 ° phase difference between the A phase and the B phase as speed and position feedback signals. To 225. The detection circuit 224 performs A / D conversion on the analog speed feedback signal from the encoder attached to the motor 203 and corrects it with the amplitude ratio / phase difference correction parameter stored in the storage unit 227 to obtain a digital signal speed feedback signal. Feedback to the speed control means. The detection circuit 225 A / D converts an analog position feedback signal from an encoder attached to the main shaft 204, corrects it with an amplitude ratio / phase difference correction parameter, and feeds it back to the position control means as a digital position feedback signal. .
A movement command is output from the numerical control device 201 to the motor control device 202, and the position control means 221 of the motor control device 202 receives the movement command from the numerical control device 201 and analog feedback from the encoder 206 attached to the spindle 204. A position feedback control is performed based on the digital position feedback signal from the detection circuit 225 that has A / D converted the signal to obtain a speed command, which is output to the speed control means 222. The speed control unit 222 obtains a torque command by performing speed feedback control by using this speed command and a digital speed feedback signal from the detection circuit 224 that converts an analog speed feedback signal from an encoder attached to the motor into a digital signal. The motor 203 is driven and controlled via the circuit 223. In the motor control device 202, the position and speed control operations described above other than the operation of the drive circuit 223 are all processed by the processor of the motor control device 202. Then, an offset, amplitude ratio, phase difference, and correction parameter are obtained by the calculation unit 226 so that the correction parameter can be written and updated in the storage unit 227. Further, the display unit 228 including an LED, a 7-segment display, and the like In this case, the obtained offset, amplitude ratio, and phase difference are displayed on the display of the numerical controller 201.
As described above, the conventional encoder parameter measuring device A / D converts the time waveform of the encoder, acquires it as a digital value, and detects the offset voltage component, amplitude ratio, and phase difference by processing the digital signal. is there.
Japanese Patent Laid-Open No. 2002-199768 (page 7, FIG. 1)

However, in the encoder parameter measuring device that analyzes the encoder signal as in the conventional encoder parameter measuring device, the rotational speed of the driving motor needs to be constant, and if there is uneven speed, the measured encoder signal The calculated position error includes this velocity unevenness component. Due to the speed ripple of the drive motor and the mechanical characteristics of the measurement system, the second harmonic voltage component and third order other than the offset voltage component, signal amplitude ratio, and signal phase difference error included in the encoder original signal. It is difficult to accurately measure harmonic voltage components.
Therefore, the present invention has been made in view of such problems, and (1) an offset voltage component and (2) a signal that are error components of an encoder signal using an accumulated error of the encoder that can be accurately detected. It is an object of the present invention to provide an encoder position error analysis apparatus that measures an amplitude ratio, (3) signal phase difference, (4) second harmonic voltage component, and (5) third harmonic voltage component error signal component.

The present invention has been made to solve the above-described problem. The invention of the encoder position error analysis apparatus according to claim 1 is an encoder position error analysis apparatus for analyzing a detected position error of an encoder. A first DFT / FFT analyzer for analysis, a second DFT / FFT analyzer for frequency analysis of the A-phase signal waveform, a frequency analysis result of a position error signal waveform by the first DFT / FFT analyzer, and the And a parameter analyzer that obtains an error signal component included in the encoder original waveform from the phase information of the primary component of the frequency analysis result of the A-phase signal waveform by the second DFT / FFT analyzer.
Thus, the frequency analysis of the position error signal and the A phase signal can be performed, and the frequency analysis result of the position error signal and the phase of the primary component of the A phase signal are analyzed by the parameter analysis device. The offset voltage component, amplitude ratio shift, phase shift, secondary voltage component, and tertiary voltage component of the signal can be obtained.
According to a second aspect of the present invention, there is provided an encoder position error analyzing apparatus that analyzes a detected position error of an encoder, a DFT / FFT analyzing apparatus that performs frequency analysis of a position error signal waveform, and the position error. A first variable frequency bandpass filter connected to a signal waveform and passing only a primary frequency component whose center frequency changes in synchronization with the primary frequency of the DFT / FFT analysis, and connected to the A-phase signal waveform and the DFT / Measures the phase difference between the second variable frequency bandpass filter that passes only the primary frequency component whose center frequency changes in synchronization with the primary frequency of FFT analysis and the output waveforms of these two variable frequency bandpass filters A phase difference measurement device, a frequency analysis result of a position error signal waveform by the DFT / FFT analysis device, and the phase difference Characterized in that it consists of a parameter analyzer for determining an error signal component contained from the output results of the measuring device to the encoder original waveform.
Thus, the frequency analysis of the position error signal can be performed by the DFT / FFT analyzer, and the position error can be measured by measuring the phase difference between the output signals of the first variable bandpass filter and the second variable bandpass filter. The phase difference between the signal and the A phase signal can be detected, and the encoder is obtained by analyzing the frequency component of the position error signal, the primary component of the position error signal, and the phase difference of the primary component of the A phase signal with a parameter analysis device. The offset voltage component, amplitude ratio shift, phase shift, secondary voltage component, and tertiary voltage component of the signal can be obtained.
According to a third aspect of the present invention, in the encoder position error analysis device according to the first or second aspect, the A phase signal waveform is an A phase pulse wave signal.
Thus, the frequency analysis result of the position error signal and the phase of the primary voltage component of the A-phase pulse signal are converted by the parameter analyzer to the offset voltage component, amplitude ratio, phase, secondary voltage component, 3 of the encoder signal. The secondary voltage component can be obtained.

Further, the invention according to claim 4 is the encoder position error analysis device according to any one of claims 1 to 3, wherein the position detection device calculates the encoder position from the A phase signal waveform and the B phase signal waveform; A reference position generation device that calculates a true value of a position by internal calculation, and a position error calculation device that calculates a position error signal waveform from the output of the position detection device and the output of the reference position generation device, Instead of the position error signal waveform used in the encoder position error analysis apparatus according to 1 or 2, a position error signal waveform that is an output of the position error calculation apparatus is used.
Thus, the encoder error signal can be detected from the A-phase signal waveform and the B-phase signal waveform of the measurement encoder, and the reference encoder required for measuring the position error signal waveform in the invention according to claim 1 is provided. It can be omitted.

According to a fifth aspect of the present invention, in the encoder position error analysis device according to the fourth aspect, the A phase signal waveform and the B phase signal waveform are output to the position error calculation device via a waveform correction device, respectively. It is characterized by.
Specifically, according to a sixth aspect of the present invention, in the encoder position error analysis device according to the fifth aspect, the waveform correction device includes a first offset voltage correction device, a second offset voltage correction device, 1, an amplitude correction device, a second amplitude correction device, a third amplitude correction device, a fourth amplitude correction device, a signal correction device comprising an adder and a subtractor, and the first offset voltage correction device, A phase signal waveform is corrected by the first amplitude correction device, a B phase signal waveform is corrected by the second offset voltage correction device and the second amplitude correction device, and the corrected A phase signal waveform The sum of the corrected B phase signal waveforms is corrected by the third amplitude correction device, and the difference between the corrected A phase signal waveform and the corrected B phase signal waveform is corrected by the fourth amplitude correction device. Correct and like this Wherein the Tadashisa the A phase correction signal waveform and the B-phase correction signal waveform and a and outputs, respectively.
Therefore, the encoder error signal can be analyzed with higher accuracy than the invention of the fourth aspect.
The invention according to claim 7 is the encoder position error analysis device according to any one of claims 1 to 6, wherein instead of the parameter analysis device, a first parameter analysis device, a position error calculation device, And a second parameter analysis device, wherein the first parameter analysis device obtains an encoder error signal component from the frequency analysis result of the position error signal and the frequency analysis result of the A-phase signal, and the encoder error A position error calculation signal is calculated from the signal component by the position error calculation device, a difference of the position error calculation signal is generated from the encoder error signal, the difference is analyzed by the second parameter analysis device, and the encoder error is calculated. It has a parameter analysis device that subtracts the output of the second parameter analysis device from the signal component.
Since this is the case, it is possible to compensate for errors caused by interference between encoder error signal components, and to detect encoder error signal components with high accuracy.
An encoder position error analysis apparatus according to claim 8 is an encoder position error analysis apparatus that analyzes a detection position error of an encoder, a ripple analysis apparatus that calculates a speed ripple from a reference encoder position signal, and a position error signal. A subtractor for subtracting the output of the ripple analyzer from the first DFT / FFT analyzer for analyzing the position error signal, a second DFT / FFT analyzer for analyzing the A-phase signal, and the first and first And a parameter analyzer that calculates encoder parameters from the signals of the two DFT / FFT analyzers. Thus, since the position error signal from which the speed ripple of the reference encoder is removed can be detected, the encoder error signal can be analyzed with high accuracy in a state where it is incorporated in the mechanical device.
The invention according to claim 9 is the encoder position error analysis device according to any one of claims 1, 2, or 8, wherein the first and second DFT / FFT analysis devices are wavelet analysis devices. It is characterized by being.
Thus, the frequency analysis of the position error signal and the A phase signal can be performed without rotating the encoder one time.

According to the encoder position error analysis apparatus according to claim 1, the A phase signal waveform and the B phase signal waveform of the encoder are calculated from the result of frequency analysis of the accumulated error of the encoder and the result of frequency analysis of the A phase signal waveform of the encoder. Can be detected, and a driving motor capable of highly accurate speed control required for a conventional encoder evaluation apparatus is not required. Therefore, there is an effect that the encoder position error analysis device can be produced at low cost.
Further, according to the encoder position error analysis device of the second aspect, the frequency analysis device can be reduced by substituting the frequency analysis of the A-phase signal waveform with the combination of the variable bandpass filter. Furthermore, since the frequency analyzer is replaced with a combination of variable bandpass filters, the analysis time can be reduced, and the cost required for the analysis can be reduced.

Further, according to the encoder position error analysis apparatus according to claim 3, since the A phase signal can be replaced by the A phase pulse signal, the Walsh transform is used instead of the Fourier transform to obtain the phase of the primary signal. Therefore, the analysis time can be reduced and the cost required for the analysis can be reduced.
According to the encoder position error analysis apparatus of the fourth aspect, the position error signal is analyzed using the A phase signal waveform / B phase signal waveform as the encoder position error signal and the signal calculated by the position error calculation apparatus. Since the error signal component included in the encoder signal is calculated, the configuration of the position error signal measuring device is simplified, and the cost required for analyzing the error signal component can be greatly reduced.
Further, according to the encoder position error analysis device according to claims 5 and 6, the position error signal obtained by inputting the result of correcting the A phase signal and the B phase signal by the waveform correction device to the position error calculation device is the frequency. Since the frequency component of the position error signal is obtained by analysis, a more accurate error signal component can be obtained as compared with the encoder position error analysis device according to claim 4.
According to the encoder position error analysis apparatus of the seventh aspect, the position error signal is calculated using the error signal component obtained by the first aspect, and the position error signal calculated from the position error signal waveform to be analyzed is calculated. A highly accurate error signal component can be obtained by analyzing and compensating the error signal for the subtraction result.
According to the eighth aspect of the present invention, the velocity ripple component of the encoder drive system can be calculated by analyzing the reference encoder with the ripple analyzer, and the position error signal obtained by subtracting the velocity ripple component is used as the DFT / FFT analyzer. Since the frequency analysis is performed by this, a highly accurate analysis can be performed in a state where it is incorporated in a mechanical device.
According to the ninth aspect of the present invention, the frequency analysis of the position error signal and the A-phase signal can be performed without rotating the encoder one time by the WAVELET analysis device. The offset voltage error, phase difference error, amplitude error, second harmonic component, and third harmonic component contained in the B phase signal can be obtained.

Hereinafter, the present invention will be described in detail with reference to the drawings.
First, in describing the present invention, the influence of the offset voltage component, amplitude ratio, phase difference, second-order and third-order harmonic components on the position error signal included in the encoder signal will be described with reference to FIGS. explain.
FIG. 13 is a diagram showing the influence of the offset voltage component of the encoder signal on the position error signal included in the encoder signal.
As shown in FIG. 13, the offset voltage component of the encoder signal is a primary component having a period of the encoder 1 pitch in the position error signal, and the primary components generated by the offset voltage components of the A-phase signal and the B-phase signal are mutually The phase is 90 ° different.
(A) is a time waveform of a sin phase and a cos phase when an offset voltage exists in the A phase. One round is 1024 pitches. The amplitudes of the A phase and the B phase are each 1 (v), and the A phase DC offset voltage is 5 (mv). (B) is a position error signal diagram in the case where only the A-phase offset voltage exists, the amplitude of the waveform of the series 1 is 1 (v), and the A-phase DC offset voltage is 5 (mv). As can be seen from comparison with the diagram of (a), the position error signal is a primary component whose period is the encoder 1 pitch, and the primary component generated by the offset voltage component of the A-phase signal is the series 1 in FIG. The position is different by 90 °. (C) is a position error signal diagram when only the B-phase offset voltage exists. The amplitude is 1 (v) and the B-phase DC offset voltage is 5 (mv). As can be seen from comparison with the diagram of (a), the position error signal becomes a primary component, and the primary component generated by the offset voltage component of the B-phase signal has a position of 90 ° compared to the series 2 of (a). It is different. (D) is a position error signal diagram when both A-phase and B-phase offset voltages exist. The amplitude is 1 (v), and the A-phase and B-phase DC offset voltages are both 5 (mv).
Thus, the offset voltage component of the encoder signal is a primary component having a period of the encoder 1 pitch in the position error signal, and the primary components generated by the offset voltage components of the A-phase signal and the B-phase signal have a phase of 90. ° It is different.

Further, due to the difference in amplitude of the two signals and the deviation of the phase from 90 °, the position error signal generates a voltage component of a secondary component, and the phase differs by 90 °.
FIG. 14 is a diagram showing the influence of the amplitude ratio and the phase difference on the position error signal. FIG. 14A shows the sin phase when the A phase amplitude is 1.01 (v) and the B phase amplitude is 1.0 (v). And a time waveform of the cos phase. Note that the phase difference = 0 and the DC offset voltage = 0.
FIG. 6B is a position error signal diagram when the amplitude ratios are different. As can be seen from comparison with the diagram (a), the position error signal generates a voltage component of a secondary component.
(C) is a position error signal diagram when there is a phase shift.
The phase shift is 0.5 degrees, both the A phase and B phase amplitudes are 1.0 (v), and the offset voltage is 0 (mv). As can be seen from comparison with the diagram (a), the phase of the position error signal is 90 ° different.

FIG. 15 is a diagram showing the influence of the second harmonic on the position error signal.
(A) is a time waveform of a sin phase and a cos phase. (B) is a position error signal diagram. As can be seen from the figure, the position error signal generates a voltage component composed of a third order component and a first order component.

FIG. 16 is a diagram showing the influence of the third harmonic on the position error signal.
(A) is a time waveform of a sin phase and a cos phase. (B) is a position error signal diagram. As can be seen from the figure, the position error signal generates a fourth-order component.
In the present invention, the error component included in the encoder signal is obtained from the position error signal using the above-described properties of the encoder error signal and the position error signal.
The present invention will be described below.

FIG. 1 is an example of a block diagram of an encoder position error analysis apparatus according to the present invention.
In the figure, a discrete Fourier transform (hereinafter referred to as DFT) / fast Fourier transform (hereinafter referred to as FFT) analysis device 21 performs frequency analysis on the position error signal 11 to analyze the first to fourth order signal components of the position error signal 11. It is the structure which can acquire intensity | strength and a phase.
The DFT / FFT analyzer 22 is configured to obtain the phase of the primary signal component of the A-phase signal waveform 12.
The parameter analyzer 30 also provides information on the intensity and phase of the first to fourth order signal components of the position error signal 11 obtained from the DFT / FFT analyzer 21 and the A-phase signal waveform 12 obtained from the DFT / FFT analyzer 22. From the phase information of the primary signal component of the signal, the amplitude ratio and phase shift of the two analog encoder signals from 90 °, the offset voltage component of each signal, the second harmonic component of each signal, the third harmonic of each signal It is the structure which can calculate a component.
Then, the parameter analysis device 30 calculates the error signal component of the two analog encoder signals by the following (Equation 1). That is,

(1) Phase A offset voltage =
(Primary component intensity of the position error signal 11) * Sin (Primary component phase of the position error signal 11 + 180 ° −Primary component phase of the A phase signal 12) / K1
− (1 / √2) * (third-order component intensity of the position error signal 11) / K6

(2) B phase offset voltage =
(Primary component intensity of position error signal 11) * Cos (primary component phase of position error signal 11 + 180 ° −primary component phase of phase A signal 12) / K1
− (1 / √2) * (third-order component intensity of the position error signal 11) / K6

(3) Amplitude ratio = A phase signal amplitude / B phase signal amplitude =
1- (Secondary component intensity of position error signal 11) * Sin (Error signal secondary component phase-2 * Primary component phase of phase A signal 12) / K2

(4) Phase difference between A phase signal and B phase signal =
(Secondary component intensity of position error signal 11) * Cos (Error signal secondary component phase-2 * Primary component phase of phase A signal 12) / K3

(5) Second harmonic component = (Error signal third component) / K4

(6) Third harmonic component = (error signal fourth component) / K5
... (1 set)

K1, K2, K3, K4, K5, and K6 are constants determined by the measuring device.

Here, FIG. 2 is a diagram showing an example of the accumulated error and an analysis / calculation result to which the first embodiment of the present invention is applied, that is, each parameter of the error signal calculated by (Equation 1) is calculated internally. Substitute the A-phase signal and B-phase signal corresponding to the true value i of the position to the following (2 · 1 formula) and (2 · 2 formula) to make a 2-phase encoder signal, and arrange it with the position error signal obtained from it It is displayed.

A phase signal = A phase amplitude * Cos [{(2 * pi) / (number of divisions in one cycle)} * i
+ (Phase difference) + (A phase signal primary component phase)]
-(Second harmonic component) * Sin [2 * [{(2 * pi) / (number of divisions in one cycle)} * i + phase difference + A phase signal primary component phase]]
+ (3rd harmonic component) * Cos [3 * [{(2 * pi) / (number of divisions in one cycle)} * i + phase difference + A phase signal primary component phase]] + A phase offset voltage
... (2.1 formula)

B phase signal = B phase amplitude * Sin [{(2 * pi) / (number of divisions in one cycle)} * i
+ (A phase signal primary component phase)] + (second harmonic component) * Sin [2 *
[{(2 * pi) / (number of divisions in one cycle)} * i + A phase signal primary component phase]]
-(3rd harmonic component) * Sin [3 * [{(2 * pi) / (number of divisions in one cycle)} * i + A phase signal primary component phase]] + B phase offset voltage
... (2.2 type)

It can be understood from FIG. 2 that the two-phase signal obtained by substituting the error signal parameter obtained from (Equation 1) into (Equation 2 · 1) and (Equation 2 · 2) can be obtained as a two-phase encoder signal. Since the error (FIG. 2b) substantially matches the position error (FIG. 2a) obtained by the actual machine, the error signal parameter obtained from (Equation 1) can be used as the error signal parameter of the encoder signal.

FIG. 3 is a diagram showing the configuration of the second embodiment.
In the first embodiment (FIG. 1), the DFT / FFT analyzer 22 for the A phase signal waveform 12 determines the phase condition of the position error signal waveform 11 and the primary component of the position error signal waveform 11 and the A phase signal waveform 12. Any structure that can calculate the phase difference may be used.
Therefore, the DFT / FFT analyzer 22 has a variable bandpass filter 42 whose center frequency is tuned to the primary signal frequency of the DFT / FFT analyzer 21 and a position where the center frequency is tuned to the primary signal frequency of the DFT / FFT analyzer 21. The error signal waveform 11 can be replaced by a variable bandpass filter 41 and a phase difference detection device 50 that detects a phase difference between the output signal of the variable bandpass filter 41 and the output signal of the variable bandpass filter 42. The phase of the primary component of the A phase signal can be obtained from the output.
Since the DFT / FFT analysis device 21 is thus replaced by the variable bandpass filter 41, the variable bandpass filter 42, and the phase detection device 50, the time required for the analysis of the A phase signal can be shortened. Can reduce the cost.

FIG. 4 is a diagram showing the configuration of the third embodiment.
In the first embodiment (FIG. 1), the A-phase signal waveform 12 was analyzed by the DFT / FFT analyzer 22 in order to obtain the phase of the primary component of the A-phase signal. However, this phase can be substituted by an A-phase pulse signal waveform 12 ′ obtained by pulsing the A-phase signal waveform 12.
Therefore, the phase of the primary component of the A-phase signal can be obtained by analyzing the A-phase pulse signal waveform 12 ′ by the DFT / FFT analyzer 22 and obtaining the phase of the primary signal component.
As described above, by using the A-phase pulse signal waveform 12 ′, the DFT / FFT analyzer 22 is not limited to the Fourier transform, and can be substituted by the Walsh transform or the like, so that the time required for the analysis of the A-phase signal is shortened. Can reduce the cost required for analysis.

FIG. 5 is a diagram showing the configuration of the fourth embodiment.
In the first embodiment (FIG. 1), the position error is determined by analyzing the position error signal of the position signal of the measurement encoder and the position signal of the reference encoder, that is, the accumulated error of the measurement encoder, to obtain the error signal component included in the encoder signal. Was done.
Instead of this accumulated error, the position error calculation result obtained from the measurement results of the A phase signal and the B phase signal may be used as the position error signal 11.
The configuration is as follows. Instead of the position error signal 11, an A phase signal waveform 12, a B phase signal waveform 13, and a position error calculation device 60 are configured.
In the position error calculation device 60, the position calculation of the encoder is performed using the A phase signal waveform 12 and the B phase signal waveform 13. Further, in the position error calculation device 60, a true value of the position is generated and compared with the calculated encoder position. The difference between the two values is output as a position error. The error signal component included in the encoder signal is detected by analyzing the position error instead of the position error signal 11.
As described above, the A-phase signal waveform 12, the B-phase signal waveform 13, and the position error signal obtained by calculation from the position error calculation device 60 are analyzed to detect the error signal component included in the encoder signal. The reference encoder required for measuring the error signal waveform of one embodiment is not required, the configuration of the measuring instrument can be simplified, and the cost required for analysis can be greatly reduced.

FIG. 6 shows a fifth embodiment of the present invention.
As can be seen by comparing FIG. 6 with FIG. 5, in the fifth embodiment, the A-phase signal waveform and the B-phase signal waveform are each once corrected by the waveform correction device 140, and then the position error is calculated. It is configured.
FIG. 7 is a block diagram showing an example of the configuration of the waveform correction apparatus 140 of this embodiment.
In FIG. 7, the waveform correction device 140 includes a first offset voltage correction device 141, a second offset voltage correction device 142, a first amplitude correction device 151, a second amplitude correction device 152, and a third amplitude correction device. 153, a fourth amplitude correction device 154, an adder 160, and a subtractor 170.
The A-phase signal waveform is subjected to offset voltage and amplitude correction by the first offset voltage correction device 141 and the first amplitude correction device 151.
Similarly, the offset voltage and the amplitude of the B phase signal waveform are corrected by the second offset voltage correction device 142 and the second amplitude correction device 152.
The adder 160 adds the A-phase signal and the B-phase signal, and the third amplitude correction device 153 performs amplitude correction to obtain an A-phase correction signal waveform.
Further, the subtractor 170 calculates the difference between the A phase signal and the B phase signal, and the fourth amplitude correction device 154 performs amplitude correction to obtain a B phase correction signal waveform.
Thereafter, the A-phase correction signal waveform and the B-phase correction signal waveform are input to the position error calculation device 60 (FIG. 6), and the position error signal is calculated. The position error signal is frequency-analyzed by the DFT / FFT analyzer 21 and included in the encoder signal using the parameter analyzer 30 from the frequency component of the position error signal and the A-phase signal phase obtained by the DFT / FFT analyzer 22. An error signal component is detected.

FIG. 8 shows the result of analysis-calculation according to the present invention together with the position error signal 11.
In FIG. 8, the vertical axis represents the position error, and the horizontal axis represents the rotation angle. As can be seen from the figure, it can be seen that the result of the analysis-calculation almost coincides with the tendency of the position error signal 11.
As described above, the A phase signal waveform 12 and the B phase signal waveform 13 are corrected, the position error signal obtained by the position error calculation device 60 is analyzed from the signals, and the error signal component included in the encoder signal is detected. Therefore, the reference encoder required for the error signal waveform measurement of the fifth embodiment is not required, the configuration of the measuring instrument can be simplified, and the cost required for analysis can be greatly reduced.

FIG. 9 shows a sixth embodiment of the present invention.
In the figure, reference numeral 30 'denotes a parameter analysis device, which replaces the parameter analysis device 30 in the first embodiment (FIG. 1).
The parameter analysis device 30 ′ includes a first parameter analysis device 31, a second parameter analysis device 32, and a position error calculation device 61.
The first parameter analysis device 31 obtains the frequency component information of the position error signal from the DFT / FFT analysis device 21 and the phase information of the primary component of the A phase signal from the DFT / FFT analysis device 22, and calculates the error component of the encoder signal. To do.
The position error calculation device 61 calculates a position error calculation signal waveform using the parameters obtained by the calculation of the first parameter analysis device 31.
The second parameter analyzer 32 obtains the difference between the input position error signal waveform 11 and the position error calculation signal waveform and the phase information of the primary component of the A phase signal from the DFT / FFT analyzer 22 to compensate for the error component. A value is obtained and compensation is added to the encoder signal error component obtained from the first parameter analyzer 31.
According to the sixth embodiment, because of such a configuration, it is possible to compensate for errors caused by interference between encoder error signal components, and to detect encoder error signal components with high accuracy. become able to.

FIG. 10 is a flowchart showing the calculation procedure of the position error calculation apparatus applied to the sixth embodiment in the first embodiment.
In step S1, the measurement position error is analyzed, and A phase offset voltage, B phase offset voltage, A phase signal amplitude / B phase signal amplitude, A phase / B phase signal phase difference, A phase / B phase second harmonic voltage The A phase / B third harmonic voltage is obtained from the above equation (1).
In step S2, the position error is calculated using the above analysis parameters.
In step S3, the position error difference is calculated from the position error difference = measured position error−calculated position error.
In step S4, the differential position error is analyzed, and ΔA phase offset voltage, ΔB phase offset voltage, ΔA phase signal amplitude / B phase signal amplitude, ΔA phase / B phase signal phase difference, ΔA phase / B phase second harmonic voltage. , ΔA phase / B phase third harmonic voltage is obtained.
In step S5, the sum of the values in steps S1 and S4 is obtained, and correction calculation for measurement position error analysis is performed.

FIG. 11 is a diagram showing the configuration of the seventh embodiment of the present invention.
When a reference encoder and a measurement encoder are mechanically coupled by a gear or the like to detect a position error signal, if the reference encoder has a speed ripple, the influence appears on the position error signal. This embodiment is for detecting a position error signal with high accuracy by removing the influence of the speed ripple of the reference encoder.
In FIG. 11, 401 is a position signal from the reference encoder, and 402 is a position signal from the measurement encoder. The measurement encoder position signal 402 is measured in synchronization with the reference encoder position signal 401. The A phase signal 12 is also measured in synchronization with the reference encoder position signal 401. The position error signal 11 is a difference signal between the measurement encoder position signal 402 and the reference encoder position signal 401. The reference encoder position signal 401 is analyzed by the ripple analyzer 71 and the velocity ripple of the encoder is calculated.
The velocity ripple and position error signal 11 is input to the differentiator 72, and the velocity ripple 14 is subtracted from the position error signal 11. The calculation result of the differentiator 72 is subjected to frequency analysis by the DFT / FFT analyzer 21. The A phase signal 12 is subjected to frequency analysis by the DFT / FFT analyzer 22. The signal strength and phase of the first to fourth frequency components of the DFT / FFT analyzer 21 and the phase of the primary frequency component of the DFT / FFT analyzer 22 are input to the parameter analyzer 30. Since the operation of the parameter analyzer 30 is the same as that of the first embodiment, detailed description thereof is omitted.
Therefore, by analyzing the ripple of the reference encoder with a ripple analyzer, the influence of the velocity ripple component of the encoder drive system on the reference encoder can be calculated, and the velocity ripple component is subtracted from the position error signal. Thus, the position error signal from which the influence of the drive system is removed can be analyzed with high accuracy by the DFT / FFT analyzer.

FIG. 12 shows the configuration of the eighth embodiment of the present invention.
Instead of the first and second DFT / FFT analyzers 21 and 22, the WAVELET analyzers 310 and 320 perform frequency analysis. The corrected position error signal 15 and the A phase signal 12 are subjected to frequency analysis by the WAVELET analysis devices 310 and 320. The offset voltage, phase difference, amplitude ratio, second harmonic component, and third harmonic component of the two encoder signals are calculated by the parameter analyzer 30 from the output results of the WAVELET analysis devices 310 and 320 as in the seventh embodiment. Is done.
As described above, since the WAVELET analysis device is used as the frequency analysis device, the frequency analysis of the position error signal can be performed without measuring the position error signal of one rotation of the encoder unlike the seventh embodiment. The offset voltage, phase difference, amplitude ratio, second harmonic component, and third harmonic component of the two encoder signals can be calculated.

1 is a block diagram of an encoder position error analysis apparatus showing a first embodiment of the present invention. FIG. It is a figure which shows an example of an accumulation error, and the analysis and calculation result to which the 1st Example of this invention is applied. It is a block diagram of the encoder position error analysis apparatus which shows 2nd Example of this invention. It is a block diagram of the encoder position error analysis apparatus which shows 3rd Example of this invention. It is a block diagram of the encoder position error analysis apparatus which shows 4th Example of this invention. It is a block diagram of the encoder position error analysis apparatus which shows 5th Example of this invention. It is a block diagram which shows the structure of the waveform correction apparatus 140 of 5th Example of this invention. It is a figure which shows an example of an accumulation error, and the analysis and the calculation result which applied 5th Example of this invention. It is a block diagram of the encoder position error analysis apparatus which shows 6th Example of this invention. It is a flowchart which shows the calculation procedure of the position error calculation apparatus which applied 6th Example of this invention to 1st Example. It is a block diagram of the encoder position error analysis apparatus which shows 7th Example of this invention. It is a block diagram of the encoder position error analysis apparatus which shows 8th Example of this invention. It is a figure which shows the influence which the offset voltage component of an encoder signal exerts on the position error signal contained in an encoder signal. It is a figure which shows the influence which an amplitude ratio and a phase difference have on a position error signal. It is a diagram which shows the influence which a 2nd harmonic gives to a position error signal. It is a diagram which shows the influence which a 3rd harmonic exerts on a position error signal. It is a block diagram which shows the conventional position error calculation apparatus.

Explanation of symbols

11 .... Position error signal waveform 12 ... A phase signal waveform 12 '... A phase pulse signal waveform 13 ... B phase signal waveform 14 ... Speed ripple 15 ... Corrected position error signals 21, 22... DFT / FFT analyzers 30, 30 ′, 31, 32... Parameter analyzers 41, 42. Phase difference measuring device 60, 61 ... Position error calculating device 70 ... Position error analyzing device 71 ... Ripple analyzing device 72 ... Difference unit 140 ... Waveform correcting device 141, 142 ... ... Offset voltage correction device 151, 152, 153, 154 ... Amplitude correction device 160 ... Adder 170 ... Subtractor 310, 320 ... WAVELET analysis device 401 ... Reference encoder position Signal 402 .... measuring encoder position signal

Claims (9)

In the encoder position error analysis device that analyzes the detection position error of the encoder,
A first DFT / FFT analyzer for frequency analysis of the position error signal waveform, a second DFT / FFT analyzer for frequency analysis of the A phase signal waveform, and a position error signal waveform by the first DFT / FFT analyzer And a parameter analysis device for obtaining an error signal component included in the encoder original waveform from the phase information of the primary component of the frequency analysis result of the A phase signal waveform by the second DFT / FFT analysis device. An encoder position error analyzer characterized by the above. In the encoder position error analysis device that analyzes the detection position error of the encoder,
A DFT / FFT analyzer for frequency analysis of the position error signal waveform; and a first frequency component connected to the position error signal waveform and passing only a primary frequency component whose center frequency changes in synchronization with the primary frequency of the DFT / FFT analysis. And a second variable frequency band-pass filter that is connected to the A-phase signal waveform and passes only a primary frequency component whose center frequency changes in synchronization with the primary frequency of the DFT / FFT analysis. A phase difference measurement device that measures the phase difference between the output waveforms of these two variable frequency bandpass filters, a frequency analysis result of the position error signal waveform by the DFT / FFT analysis device, and an output result of the phase difference measurement device. An encoder position characterized by comprising a parameter analysis device for obtaining an error signal component included in the encoder original waveform Difference analysis equipment.   3. The encoder position error analysis apparatus according to claim 1, wherein the A phase signal waveform is an A phase pulse wave signal.   A position detection device that calculates the encoder position from the A-phase signal waveform and the B-phase signal waveform, a reference position generation device that calculates a true value of the position by internal calculation, an output of the position detection device, and an output of the reference position generation device And a position error calculation device for calculating a position error signal waveform from the position error signal waveform used in the encoder position error analysis device according to claim 1 or 2, wherein the position error signal waveform is an output of the position error calculation device. The encoder position error analysis apparatus according to any one of claims 1 to 3, wherein an error signal waveform is used.   5. The encoder position error analysis apparatus according to claim 4, wherein the A phase signal waveform and the B phase signal waveform are respectively output to the position error calculation device via a waveform correction device.   The waveform correction device includes a first offset voltage correction device, a second offset voltage correction device, a first amplitude correction device, a second amplitude correction device, a third amplitude correction device, a fourth amplitude correction device, A signal correction device comprising an adder and a subtractor, wherein the first offset voltage correction device and the first amplitude correction device correct the A-phase signal waveform, and the second offset voltage correction device and the first The B phase signal waveform is corrected by the second amplitude correction device, the sum of the corrected A phase signal waveform and the corrected B phase signal waveform is corrected by the third amplitude correction device, and the corrected A The difference between the phase signal waveform and the corrected B phase signal waveform is corrected by the fourth amplitude correction device, and the corrected A phase correction signal waveform and the B phase correction signal waveform are respectively output. A contract characterized by being Encoder position error analysis apparatus in claim 5.   In place of the parameter analysis device, a parameter analysis device including a first parameter analysis device, a position error calculation device, and a second parameter analysis device, the frequency analysis result of the position error signal and the frequency analysis of the A phase signal An encoder error signal component is obtained from the result by the first parameter analysis device, a position error calculation signal is calculated from the encoder error signal component by the position error calculation device, and a difference of the position error calculation signal from the encoder error signal is calculated. 7. The apparatus according to claim 1, further comprising: a parameter analysis device that generates and analyzes the difference by the second parameter analysis device and subtracts the output of the second parameter analysis device from the encoder error signal component. The encoder position error analysis apparatus of any one of Claims. In the encoder position error analysis device that analyzes the detection position error of the encoder,
A ripple analyzer that calculates velocity ripple from a reference encoder position signal, a subtractor that subtracts the output of the ripple analyzer from a position error signal, a first DFT / FFT analyzer that analyzes a position error signal, and an A-phase signal Encoder position characterized by comprising: a second DFT / FFT analysis device for analyzing the signal; and a parameter analysis device for calculating encoder parameters from the signals of the first and second two DFT / FFT analysis devices Error analysis device.   9. The encoder position error analysis apparatus according to claim 1, wherein the first and second DFT / FFT analysis apparatuses are wavelet analysis apparatuses.

Images