SU1241473A1 - Shaft turn angle-to-digital converter - Google Patents

Abstract

The invention relates to the field of automation and high-tech equipment and is intended for measuring angular movements in control systems of machine tools, radio and optical telescopes. The aim of the invention is to increase the reliability of the converter. The goal is achieved by the fact that digital-to-analog converters (D / A) 12 and 13 and a block 14 of inverters are introduced into the converter. When the converter shaft is rotated, the signals at the outputs of photodetectors 1-4 are formed, shifted by a quarter of the track of the code disk. The decoder 9 converts these .signals into a three-digit coarse reference code (GO). D / A 12 and 13 are connected to the outputs of the exact reference, and the DAL 13 is connected to it through a block of 14 inverters. As the code grows in the exact reference channel (TO), sawtooth voltages are formed at the outputs of the D / A converter 12 and 13, and the DAC I2 has an increasing amplitude, and the DAC 13 output has a decreasing amplitude. These voltages control the switches 10 and 11, which are used to coordinate the coarse and accurate readings of the converter. 2 Il. & (L to 4; with

Description

112

The invention relates to automation and computing and can be used in software systems for controlling machine tools, in radio and optical telescope control systems.

. The aim of the invention is to increase the reliability of the converter.

Fig. 1 shows a functional diagram of one reference transducer for the case of four reading elements; Fig. 2 is a spatial diagram explaining its operation,.

The converter contains radiation sources, a code disk with annular coding (not shown in the drawing), photodetectors 1-4, comparators 5-8, decoder 9, mutators 10 and 1 1, digital-to-analogue converters (D / A) 12 and 13, block 14 of inverters .

The Converter operates as follows.

When the code disk is rotated on photodetectors 1-4, signals are generated which are formed by comparators 5-8 into square signals shifted by one quarter of the quantum track of the disc of its count. The decoder 9 converts these signals into a three-bit binary code. Their matching with the previous count, which may be a more accurate count of the same transducer, accomplished in the same way, is accomplished by controlling the threshold voltages of the comparators that are generated by the digital counters 12 and 13 from the output signals of the previous count. The inputs of the DAC 12 are connected to the outputs of the bits of the previous sample directly, therefore, as the code increases in the previous sample, the linearly increasing voltage is formed at the output of the DAC 12, which is used to match the leading edges of the signals. The inputs of the D / A converter 13 are connected to the outputs of the previous sample bits via a block of 14 inverters, therefore, as the code increases in the previous sample, a linearly decreasing voltage is formed at the output of the D / A converter 13, which is used to match the falling edges of the signals of the matching sample. Figure 2 shows diagrams explaining the process of matching the transducer samples. In the case under consideration, four were used to form the threshold voltages.

473. Z

older bit previous exact

CAL 12 and 3 form the threshold voltage so that the maximum value of this voltage U (does not exceed half the amplitude of the signals read by the photoreceivers 1-4, and the upper value does not exceed the amplitude, but there was more than half the amplitude of the signals of the photoreceivers 1- 4, The threshold voltages generated by the DAC 12 and 13 through the switches 10 and 11 are fed to the inputs of the comparators. 5-6, If there is a switch 10 on the control input

5 high level, its output receives a signal from the output of the DAC 12, and if there is a low level on its control input, the signal from the output of the D / A converter 13, the Switch 11 operates in the same way as

0 with the difference that at a high level, on its controlling input 6 and 1, its output passes the signal from the output of the D / A converter 13 and, conversely, at a low level at the control input of switch 11 to the output

5 passes the signal from the output of the DAC 12.

When the converter shaft is rotated by an angle equivalent to one low-order bit of the matched reference, the code at the inputs of the DAC 12 gradually changes from 0000 to 1111. At the same time, the voltage at the output of the DAC 12 increases in steps from the minimum value of U to the maximum U, At Further rotation of the code disk, the code is changed at the input of the DAC 12 from MP to 0000 and the voltage at its output changes abruptly to level U. If, in addition, the amplitude of the matching signal is greater and, but less than Ug (position 0 in FIG. 2) then the output of the matching comparator 5-8, a logical unit is generated, i.e. A simultaneous code change is performed in counts. During the formation of the trailing edge, the threshold voltage generated by the DAC 13, which changes from c and, to and, when changing the code in the output voltage, arrives at the input of the comparator 5, 6, 7 or 8 through the switch 10 (11).

CL,

the previous countdown from 1111 to 0000, since the inputs of the DAC 13 are connected to the outputs of the bits of the previous counting through inverters 14,

The switch 10 (11) 55 is controlled by a signal from another comparator, which switches the outputs of the DAC between the fronts of the matched signals.

0

S

where A is the amplitude of FIG. 2, a case is considered when the width of the working sections of the photodetectors 1-4 is 3.75 quanta older than the previous counting minimum and maximum values of the threshold voltages, respectively

The values of the matched signal are equal and, d-, U2, and the head of the previous bits of the exact reference is used to form the threshold voltages. In this case, the read line 00 can occupy any position in the interval from OO to OO, within which the conditions for matching the samples are not violated. Such a displacement of the read lines (Fig. 2) is equivalent to the displacement of the working sections of the photodetectors 1–4 or the boundaries of the strokes of the track by the value of +15/16 quantum of the track of the previous reference.

With the increase in the number of bits used to form the threshold voltages and with the expansion of the working sections of the photodetectors 1-4 to four quanta of the track of the previous sample, the step form of the threshold voltages approaches the sawtooth, and the zone of acceptable displacement of the read line approaches the limiting j value: l quantum track previous count.

35

Thus, the proposed converter allows to expand the tolerances for the manufacture of a code scale and the arrangement of the working sections of the photodetectors, bringing them closer to the largest fundamentally attainable value,. to increase the working areas of the photodetectors, which increases the signal-to-noise ratio and thereby increases the reliability of the converter.

Claims (1)

5 Formula of Absorption A shaft rotation angle converter into a code containing, in each sample, radiation sources optically connected through a code disk to photodetectors, the outputs of which are connected to the first inputs of the corresponding comparators, the outputs of which are connected to the decoder information inputs, which are outputs converter, the output of the first comparator is connected to the first input of the first switch, the output of which is connected to the second inputs of the remaining comparators, the output of the second comparator is connected to the first input the second switch, the output of which is connected to the second input of the first comparator, is necessary in order to increase the reliability of the converter; two digital-analog converters and an inverter unit are introduced into it, the information inputs of the first the digital-to-analog converter and the inverter unit are combined and are the information inputs of the converter, the outputs of the inverter unit are connected to the information inputs of the second digital-to-analog converter, the output of which is connected to the second inputs of the first and second th switches, the output of the first digital to analog converter coupled to the third, inputs of said first and second commutators. ditch ff in 0ue, Z LTD VNIIPI Order 3614/56 Prod-polygr. pr-tie, Uzhgorod, st. Project, 4 Circulation 816 Subscription