SU1711328A1 - Method of conversion of shaft rotation angle into code and device - Google Patents

Abstract

The invention relates to automation and computer technology and can be used in software devices for controlling machine tools, as well as in telescope control systems. The purpose of the invention is to improve the accuracy of converting the angle of rotation of the shaft to a code by generating digital signals from analog signals at shaft positions corresponding to angles with a period within measurement step 27, while eliminating the influence of the shape of the analog signals and the amount between them. For this, the first analog signal is shifted in the first summing amplifier to match; with a zero level of its values corresponding to angles of 0, b, 27. The second analog signal is shifted in the second summing amplifier and added to the part of the first analog signal until it coincides with the zero level of the total signal corresponding to angles 1/2 and 3/2. Thus, the third and fourth analog signals are converted by two comparators, the first element of the volume EXCLUSIVE OR, into the two-level signals of the first and second code bits, controlling the first switch, the fifth and sixth analog signals, whose values are set at the help of four controlled voltage dividers is equal at the angles If /, H /, SAff and 7 / b, the second comparator u Forms the second o. wuhu even logical signal according to the results of craw- | The second and sixth analog signals, modulo two with the second bit of a code, generates a two level third bit and also controls the second switch. The remaining bits of the output code are formed within the octants by an analog-to-digital converter of the fifth or sixth analog; two signals, modulo two with the second bit, the code, forms a two-level signal of the third bit, and also controls second switchboard. The remaining bits of the output code are formed within the octants by an analog-to-digital converter from the fifth or sixth analog signal coming from the output of the second switch, 2 cf f-ly. 3 ilso gchz 00

Description

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The invention relates to the field of automation and computer engineering and can be used in devices for software control of machine tools, as well as in telescope control systems.

The purpose of the invention is to improve the accuracy of the conversion.

Figure 1 shows a block diagram of a device for converting an angle of rotation of a shaft into a code; 2 and 3 are diagrams illustrating the operation of the device.

The device for converting the angle of rotation of the shaft into a code contains a converter 1 of the angle of rotation of the shaft into analog signals consisting of a block of 2 emitters, a measuring 3 and indicator discs, photo detectors 5 and 6, and amplifiers 7 and 8, signal offset blocks made in the form of summing amplifiers 9 and 10, adjustable source 11 DC, inverters 12 and 13, adjustable voltage dividers, comparators 19-21, elements 22 and 23 EXCLUSIVE OR, switches 2 and 25, analog-to-digital converter (ADC) 26.

The method of converting the angle of rotation of the shaft into a code is considered on the example of a device that operates as follows.

The luminous flux from the emitter unit 2 through the slits of the measuring 3 and the indicator 4 disks hits the sensitive areas of the photodetectors 5 and 6, at the outputs of which electrical signals are generated,. proportional to the padaktsemu on them the luminous flux. The first and second analog signals generated by amplifiers 7 and 8 are fed to the outputs of converter 1. When the shaft of converter 1 is rotating, the radiation is modulated by raster coupling. disk drives 3 and 1 and the outputs of the converter 1 form signals U, and Ug, .. noi form close to sine wave

35

40

45

With these measurement steps, the phase shift by the signals is close to / and / 2, where 2fr corresponds to the measurement step. The phase shift between signals from the nominal value of / 2 is turned off due to errors occurring when drawing strokes on the original of the dicker disk k during photolithography and the presence of residual eccentricity of the indicator tsiska Such parameters of the bitmap as the ratio of the areas of transparent and opaque disk strokes 3 and C within the step of measurement, as well as the characteristics of the radiation pattern of the radiators of the block 2, determine the non-sinusoidality of the lines of U4 and U, which can be expressed in the form of asymmetry of their shapes s relative to the average level of Nogo UCppo amplitude signals (2E).

The signals shown in Fig. 2a, o are formed in the case when the width of the projections of the transparent strokes of the indicator disk 4 exceeds the width of the transparent strokes of the measuring dis 3 in the plane of the latter. When forming rectangular signals by the average level Ucp, ensuring equality of amplitudes of negative and positive half-wave signals, angular errors & b (, Ab (Fig. 20), leading to an error in not only these points, but also in conversion range.

The signals U and are fed to the summing amplifiers 9 and 10, to the second inputs of which from a controlled constant voltage source 11, the bias signals generated in it (voltages DQ and U0J. Voltage U0 are chosen equal to the value of the signal U should be at the angles O of the opposite sign. At the output of summing amplifier 9, a third analog signal Uj is formed, which takes zero values at the points 0, and and 2ff, coinciding in shape

koto and 1G and

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and, | Y ug, 1il ilplgchps gh -nnjri, w-KZH U, and ZK, software FORMV SOVPADUERSHI

ideal (figs, o), i.e. effected -50 with the signal U, (fig.2). Permanent

The conversion of the angle of rotation of the shaft into the first and second analog electrical signals.

The phase shift between these signal voltages, V0i, is chosen to be equal in magnitude to the value of the signal U at angles ft / 2 and 3/21 °. As a result of the addition of the signal U. with the signal UQ

Lamy is determined by the relative position-5 due to errors the real signal

by display rasters k. When the raster of the indicator disk is shifted by an amount that is a multiple of four quarters (Fig. 2 &),

shift relative to the signal is equal to / 2.

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With these measurement steps, the phase shift between the signals is close to / and / 2, where 2fr corresponds to the measurement step. The deviation of the phase shift between the signals from the nominal value of / 2 is due to errors that occur when strokes are applied to the original indicator disk k during photolithography and the residual eccentricity of the indicator tsiska 4, such raster matching parameters as the ratio of areas of transparent and opaque strokes of disks 3 and Within the limits of the measurement step, as well as the characteristics of the radiation pattern of the radiators of block 2, the non-sinusoidal nature of the signals U4 and U is determined, which can be expressed in the form of a the symmetry of their shape relative to the average level of the UCp total signal span (fig.2D).

The signals shown in Fig. 2a, o are formed when the width of the projections of the transparent strokes of the indicator disc 4 exceeds the width of the transparent strokes of the measuring disc 3 in the plane of the latter. Angular errors & b (, Abd (Fig. 20), resulting in an error not only at these points, but throughout the entire range, occur when the rectangular signals are formed over the g Ucp average level, ensuring the amplitudes of the negative and positive half-wave signals are equal. transform.

The signals U and arrive at summing amplifiers 9 and 10, to the second inputs of which from an adjustable source 11 of constant voltage are applied the bias signals generated in it (voltages DQ and U0J. Voltage U0 is chosen to be equal to the angles O are inverse to the sign. At the output of summing amplifier 9, a third analog signal Uj is formed, which takes zero values at points 0 and and 2ff, coinciding in shape

which is 1G and

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KZH U, AND ZK, FOR FORMW TIPS

0 with a signal U, (fig.2). Permanent

Voltage V0i is chosen to be equal in magnitude to the value of the signal U at angles ft / 2 and 3/21. As a result of the addition of the signal U. with the signal UQ

due to inaccuracies the real signal

due to inaccuracies the real signal

ul (Fig.2 &) will have a phase

shift relative to the signal is equal to / 2.

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The signal is inverted by the inverter 12 and is fed to the input of a regulated voltage divider 14, the "second input" of which receives the first signal U from the output of summing amplifier 9.

Part of the direct (Alb) or inverted (AUj) (Fig. 2k) signal

U:

(depending on the sign of the deviation of the phase shift) from the output of divider 1 enters the third In the course of the summing amplifier 10. Since the waveform is close to sinusoidal, the output of the amplifier 10 is generated and (Fig. 2). i

U4 and

Die

Um.cos (0 + A0) -tt

COS0COS & 0 + Li sinQ Um2

- Um sinQsin Л0 + Д Uw sin0,

where dv is the deviation of the phase shift between the signals Uj and Ug from the value fr / 2 ,.

Since the value of yb is small, then put cos & 9 1, and, having denoted sinuQ k, have

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0 + kU sin0

+ Auf ainti). thirty

The output voltage of divider 14 is chosen to be

A ° 3 A% sin0 - -kumasin6- In this case, at the output of amplifier 10, a fourth analog signal U4 Um2cos Ф is shifted out of phase relative to the signal U by an amount of and / 2 and receiving zero values at angles and / 2 and 3/2% (Fig .2).

In the comparators 19 and 20 operating in the zero-organ mode, a two-level signal of the first code bit and a first two-level logic signal, offset from the two-level signal of the first bit of the code by a quarter measuring step, are formed from the analog signals U and $, respectively. Fig.2,6). The fronts of these signals coincide. Corresponding with the angles 0, 2 tf and b / 2, 3 / 2ftV. As a result of modulo two, the EXCLUSIVE element at its output forms a two-level signal of the second bit of the code (Fig. 2g). Direct and inverted inverters 12 and 13 signals Oz and U + through

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adjustable dividers 15-18 are fed to the inputs of the switch 24, to one of the inputs of which a signal U is fed directly. Switch 24 is controlled by two-level signals of the first and second code bits in such a way that at one of its outputs with a low level of two .jt of the first bit of the highlight code; the direct signal Uj, coming from the output of divider 15, is made, and when you -; Juice level - inverted signal; Uj from the output of the Divider 16.

At the other output of the switch 2k, at different levels of the two-level signals of the first and second code bits, the inverted signal 1b is separated from the output of the divider 17, at low levels of the signals of the first and second bits, the direct signal U4 from the output of the amplifier 10, and at high levels level x is the direct signal U from the output of divider 18. The fifth and sixth signals Uj- and U of fig.3a, °), formed at the outputs (switch 24, are compared with a comparator 21, at the output of which a second two-level logical signal is formed sky signal, the fronts of which correspond to the corners, with toryh voltage signals and Ug equal.

Adjustable voltage divider 15 at the angle G / h the value of the direct signal Y is set equal to the value of the direct signal U, divider 17 at an angle of 3/4 if the value of the inverted signal U is equal to the value of the direct signal U at the output of the divider 15, divider 16 at an angle of 5/4 "the value of the inverted signal U is set equal to the value of the direct signal U4 at the output of the divider 16, a divider 18 at an angle of 7/4 and the value of the direct signal U is set equal to the value of the inverted signal Uj at the output of the divider 16, c The type of signal generation $ and allows to eliminate the effect of the symmetry of the half waves of the signals U and Ug. relative to the abscissa axis, as well as the possible asymmetry of each of the half-waves relative to the ordinate axis with the least number of adjustments. To implement the method, it is possible to increase the number of adjustable voltage dividers up to eight and set the magnitude of the signals at the respective angles to the required value or the value of one

from the signals in an arbitrary sequence, providing the necessary algorithm for controlling the switch 2k with two-level signals of the first and second bits of the output code.

Thus, the fronts of the second two-level logic signal at the output of the comparator 21 are formed at angles Y / 4, 3 / 47G, B / DGG 7A1G, i.e. The second formed two-level logical signal is shifted relative to the two-level signal of the second bit of the code by a quarter of a step (Fig. 3b). These signals are summed over. 15 I am fashioning two elements of ISKLIJPE Ё OR. 23, the output of which produces a two-level signal of the third bit of the output code (Fig. 32).

The signals U, - and Ug arrive at the inputs of the switch 25, which is controlled by the second two-level logic signal generated by the comparator 21, so that its output is a signal I5 at a low level of the second two-level logical signal, and at a high level - signal Ug.

From the switch output 25, the analog signal (fig.Zf), in the form of close to 30 triangular, is fed to the input of the ADC 26, where the two-level signals of the remaining (lower) bits of the code are formed.

With a linearly increasing branch 35 of the analog signal entering the inputs, A / D converter 26, a direct code is generated at its output, and with a linearly falling branch, the code at the output of A / D converter 26 is inverted by a two-level signal of the third digit of the code.

Minor code bits can be formed by ADC 26 as well as the ratio of the analog signal at the output of the switch 25 and another analog signal obtained by converting the signals using a similar switch that is controlled so that when the signal is low at the comparator output 21, you need to switch to low. 50 signal Ug, and at high - Ug. In both cases, the residual conversion error within the octants of the phase shift can be eliminated using a permanent memory device.

Thus, the proposed method of converting the angle into a code, in addition to the conversion error caused by the deviation of the phase shift of the analog signals at the output of the converter 1 from the nominal one, makes it possible to eliminate errors caused by different types of signal asymmetry and resulting from different manufacturing errors, the effect of which increases with increasing resolution of converters, and thereby increase their accuracy.

Claims (2)

1. A method of converting an angle of rotation of a shaft into a code based on converting an angle of rotation into the first and second phase-shifted analog signals relative to each other, the period of which is equal to the quantization angle of the angle of rotation of the shaft, forming the First and second constant offset signals, forming the third and the fourth analog signal, simultaneously inverting the third analog signal and generating a two-level signal of the first bit of the code by comparing the magnitude of the third analog signal with zero y to form the first two-level logical signal, generate a two-level second-bit signal by summing modulo two two-level signal of the first bit of the code with the first two-level logical signal, generate a two-level third-level signal of the code, and generate two-level signals of the remaining code bit different in order to increase the accuracy of the conversion, in it the first constant bias signal is formed by the value of the first analog signal Signal at phase shifts 0 and C and opposite in sign, the second constant signal of displacement is formed equal to the value of the second analog signal at phase shifts IT / 2 and 3/2 7G and inverse in sign, the third analog signal is formed equal to the sum of the first analog signal and the first constant bias signal,. the fourth analog signal is formed equal to the sum of the second analog signal, the second constant the bias signal and the parts of the direct or inverted third ana-g, the log signal, the first two-level logic signal is formed by comparing the value of the fourth analog signal with a zero level; at the same time, the fourth analog signal is inverted, form -. The fifth analog signal is equal to the third analog signal at a low level two-level signal of the first code and equal to a part of the inverted third signal on a high signal at a high level of the first digital code, a sixth analog signal equal to the fourth analog signal at low levels of two-level signals of the first and second bits of a code, part of a fourth analog signal with high levels of two-level signals of the first and second bits of a code, and part of an inverter At different levels of two-level signals of the first and second code bits, the fifth and sixth analog signals are compared, the second two-level logic signal is formed by a two-level signal of the third code bit by modulating the two two-level signal of the second bit Yes code with the second two-level logic signal. The formation of two-level signals of the remaining bits of the code is carried out by analog-to-digital conversion of and a sixth analog signal, wherein at a high level, bi-level signal, the third discharge result code analog-to-digital conversion is inverted. 2. Device for converting the angle of rotation of the shaft into a code containing a converter of the angle of rotation of the shaft into analog sigals, the first and second outputs of which are connected to the first inputs of the first and second blocks of the signal bias, the output source of the first voltage, the signal is connected to the input of the first inverter and the first input of the first comparator, the second input of which is connected to the zero potential bus, and the output is the output of the first digit of the converter code and is connected , f5 20 25 here, four§ , five with the first input of the first EXCLUSIVE OR element and the first control input of the first switch, the output of the second signal bias unit is connected to the first input of the second comparator, the output of which is connected to the second input of the first EXCLUSIVE OR element, the output of which is - with the output of the second code converter, analog-to-digital converter, the outputs of which are outputs of the others, starting with the fourth, bits of the converter code, the second switch, so that, in order to improve the accuracy the second element EXCLUSIVE OR, the third comparator, five adjustable voltage dividers and the second inverter, and the signal bias blocks are designed as summing amplifiers, the second inputs of which are connected to the corresponding outputs of the regulated DC source, the output of the first summing the amplifier is connected to the first input of the first adjustable voltage divider and through the second adjustable voltage divider is connected. To the first information input of the first switch, the output is not The first inverter is connected to the second input of the first adjustable voltage divider and through the third adjustable voltage divider is connected to the second information input of the first switch: the second input of the second comparator is connected to the zero potential bus, the output of the first element EXCLUSIVE OR is connected to the second control unit equaling input of the first switch and with the first input of the second element EXCLUSIVE OR, whose output is the output of the third bit of the converter code and connected to the control input of the analog-digital The second converter, the output of the second summing amplifier, is connected to the third information input of the first switch, through the second inverter connected in series and the fourth adjustable voltage divider connected to the fourth, and via py: adjustable voltage divider to the fifth information inputs of the first switch , the outputs of which are connected to the information inputs of the second switch and the inputs of the three-. the comparator, the output of which is connected to the second input of the second element EXCLUSIVE OR, and to the control input of the second switch, is 5 the course of which is connected to the information input of the analog-digital converter. --I M M IЯ / g. E