SU1287288A1 - Shift-to-digital converter - Google Patents

Abstract

The invention relates to automation, in particular to motion transducers in code. The aim of the invention is to improve the accuracy of the converter. For this purpose, a motion converter containing a sensor 1, an analog-to-digital converter 2, and a block 3 for forming pulse counts and a reversible counter 4, a generator 6, a block 5 for voltage correction, and a block 7 for control are entered into the code converter. The goal is achieved due to the fact that the number of periods of the variable signal of sensor 1 is converted into a coarse reference code, and the value of the output signal of sensor 1 is converted into an accurate reference code using an analog-to-digital converter 2, the reference voltages for which are formed from the maximum and minimum values of the output signal sensor. zp f-ly, 6 ill. S

Description

Phage. R

The invention relates to automation, in particular to motion transducers in code.

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

FIG. 1 is a functional diagram of a displacement transducer to a code; in fig. 2 - analog-digital converter circuit; on fig.Z

a circuit for forming calculating pulses; in fig. 4 is a diagram of a voltage correction block; in fig. 5 is a control block diagram; in fig. 6 - time diagrams that show the work of the converter.

The displacement transducer to the code contains a sensor 1, an analog-to-digital converter 2 (ADC), a counting pulse shaping unit 3, a reversible counter 4, a voltage correction block 5, a generator 6 and a control block 7.

A / D converter 2 contains resistors 8.1–8. K and comparators 9.1–9. K, inputs 10 and 11 of the reference voltages and input 12 of the measured voltage.

The counting pulse shaping unit 3 contains differentiating circuits 13.1 - 13. (K + 1), each of which is executed as an EXCLUSIVE OR 14 element and NOT 15 and 16 elements with a signal delay, an OR element 17, an NOT 18 element, an OR 19 element. 22, inputs 23-25 and outputs 26-29.

The voltage correction junk 5 contains comparators 30 and 31, sampling-storage devices 32–35, a HE element 36, inputs 37–41, and outputs 42–45.

The control block 7 contains the elements NOT 46 and 47, the elements NOT 48 and 49 with a signal delay, the elements EXCLUSIVE OR 50 and 51, the elements AND 52 - 54, the triggers 55 - 57, the inputs 58 - 61 and the outputs 62-64.

The Converter operates as follows.

When a measuring body (not shown) is moved, an electrical signal appears at the first output of sensor 1 (Fig. 6, plot 65, - illustrates the case of moving the measuring body in one direction with constant speed). At the second output of sensor 1, an electrical signal similar to the first appears.

- ten

-

15

20

25

thirty

35

40

45

50

55

but shifted relative to him by a quarter period. .

The electrical signal 65 is fed to the input 37 of the voltage correction unit 5. The input 39 of the block 5 receives the signal from the second output of the sensor 1, and the input 38 serves to receive the signals of the generator 6. The current values of the voltage of the signal 65 are written down. in the sampling-storage device 32, the control pulses 66 (Fig. 6) of the generator 6. At the time O at the output of the generator 6, the recording in the device 32 of the current signal voltage 65 stops and the comparator 30 compares the current signal voltage 65 with the voltage recorded in the device 32 (Fig. 6, pos. 67). During the transition, the signal 65 through the extremum switches the comparator 30 (Fig. 6, pos.68). Thus, the moments of extremes of the signal 65 from the first output of sensor 1 are detected. Similarly, the moments of extremes of the signal from the second output of sensor 1 follow. Then, from the outputs 42 and 45 of the block 5, the signals of the comparators 30 and 31 are fed to the inputs 58 and 59 of the control block 7, respectively. The signal 65 from the output of the EXCLUSIVE OR 50 element is fed to the inputs of the AND 52 - 54 elements. And the 52 element emits pulses that occur at the time of the minimum signal 65, and state 1 appears at the output 62 of the block 7 (Fig. 6, pos. 69 ), which, on the clock pulse input, changes to the O state. Similarly, the signal 70 at the output 64 of the unit 7 is forked. c when the transition signal 65 through a maximum. Signals 68 and 69 (Fig. 6) are fed to inputs 40 and 41 of block 5 and serve to control the recording in device 34 and 35 of the maximum and minimum voltages of the signal 65.c from the output of the device, respectively.

At the moment of changing the direction of movement, an extremum arises, the recording of which in devices 34 or 35 is prohibited by the signal from the output of element 51 formed at the moment of switching the comparator 3. It uses the fact that at the moment of changing the direction of movement the extrema on the curves of the signals from the first and second outputs of sensor 1 appear simultaneously, and in all other cases, spacing 3

for a quarter of a period. In addition, at the moment of reversal, at the output of the element And 53 a pulse is formed, switching the trigger 56 into a new state. The control unit 7 can have an installation input 61, and a pulse to which, before starting the measurement, sets the output 63 corresponding to the positive direction of movement. (eg

level O). The signal 68 (Fig. 6) from the output 42 of the block 5 also enters the input 23 of the block 3 for forming countable pulses, where, by its differences, the differentiating element 13.К + forms short counting pulses 71 (Fig. 6), which, depending on the logical state Neither input 25, connected to output 63 of block 7, arrives at the output of the forward 26 or reverse 27 coarse scale counts. Between the instants of the appearance of two consecutive counting pulses 71 (Fig. 6) of a coarse scale, the measuring body moves a distance equal to the half-cycle of the output signal of sensor 1. The movement measurement with high resolution allows an interpolation device based on ADC 2, and the reference signal is supplied at both its entrance 10 and ii. Levels 72 (FIG. 6) of quantization are distributed between reference voltages at inputs 10 and 11 of A / D converters 2

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From outputs 26 and 27, the counting pulses of a coarse scale1 are fed to the input of the direct or reverse counting of the discharge with the number m) of the reversible counter 4, where K is the number of comparators 9, - 9.K in AShch1 2, as well as to the installation inputs in O in 1, depending on the direction of movement of the lower (from the 1st to the tth) bits of the reversible counter 4. Thus, the resolving power of the converter is () times greater than the resolution of the raster scale of the sensor 5 1. The number of coarse bits Scales are selected in accordance with the maximum value of EP emogo no displacement.

Splitting the reversible counter 4 into two groups for counting the coarse and vernier scales separately and introducing a reset of the vernier scale group according to the coarse scale label reduces the requirement for speed vernier markers.

In this case, the vernier scale is needed only immediately before the measurement organ stops; at a low speed of movement. At a high speed of movement, the coarse scale works, and the vernier can be turned off, so the kick of the result of its work is known in advance - it

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five

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Such a construction of the A / D converter 2 will be overwhelmed at every step.

run analog subtraction operations of reference voltages, which simplifies the procedure and eliminates one of the sources of error.

The electrical signal 65. (Fig. 6) from the first output of the sensor I is supplied

to the input 12 of the ADC 2. In the process of comparing the voltage of the signal 65 with the levels of 72 (Fig. 6 quantization at the outputs of the comparators 9.1 to 9. To the ADC 2, a corresponding unitary code appears at the inputs 24 of the block 3. Signals from the inputs 24 through the differentiating circuits 13.1–13.K, analogous to the circuit 13.K + 1, arrive at the inputs of the element OR 17. The counting pulses 73 thus obtained on the vernier scale (Fig. 6) arrive at the output of the forward 28 or reverse 29. counting block 3, from where the pulses of the 73nial scale follow to the input of the first bit of the direct or reverse counting reversing about counter 4.

coarse scale. A similar mode of operation is possible in almost all cases, except for systems with following feedback.

Reducing the influence of the change of the magnitude or constant component of the electrical signal 65 from the first output of the sensor 1 on the accuracy of the measurement of movements is ensured by the fact that each period the unit 5 adjusts the reference voltages from the outputs 43 and 44 to the inputs 10 and 11 of the reference voltage zheniy.

Claims (1)

1. The displacement transducer in the code containing the sensor, the first output of which is connected to the information input of the analog-digital converter, the outputs of the transducer are connected to the information inputs of the V1.1 IS.ff P 12 Phi. 2 3.1 U .9.k 97 S6 4J 3 € t П- 0 Const. bl Fi.b