SU1559406A1 - Displacement-to-code converter - Google Patents

Abstract

This invention relates to analog-to-digital automation elements. The aim of the invention is to improve the accuracy of the converter and the reliability of determining the limits of the range of conversion. To do this, a second function transducer is introduced into the transducer transducer into a code containing a transformer sensor, four amplitude detectors, two comparators, an alternating voltage source, a reference voltage source, a switch, the first functional transducer, and an analog-to-digital converter. When a moving element is located within the conversion of movements at the outputs of the comparators, low-level voltages are set and the output of the second functional converter is connected to the input of the analog-digital converter, which, together with the first functional converter, reproduces the dependence of the coordinates of the moving element on the detected signal . The values of the input code of the analog-digital converter are proportional to the controlled coordinate and do not depend on the non-working transverse displacements of the moving element. When the moving element is removed from the conversion range, a high level voltage is set at one of the comparators, a reference voltage source is connected to the A / D converter input, and a high level signal is set at the information outputs. 6 Il.

Description

This invention relates to analog-to-digital elements of an automation system.

The aim of the invention is to improve the accuracy of the converter and the reliability of determining the limits of the range of conversion.

FIG. 1 shows the elements of the sensor and the functional diagram of the displacement transducer to the code; in fig. 2 and

3 - plots of dependences of the output voltages of the detecting unit on displacements, respectively, in the absence and presence of play of the monitored object; in fig. 4 shows the dependences, built in relative units, of the output voltages of the two detectors used to generate information about the current values of the monitored coordinate; in fig. 5 - graphics

the inverse functions shown in FIG. 4j in FIG. 6 - functional diagrams of the first and second functional converters.

.

The converter contains a transformer sensor 1, an alternating voltage source 2, a detecting unit 3, functional converters 4 and 5, a comparators unit 6, a switch 7, an analog-to-digital converter (ADC) 8, a reference voltage source 9. Transformer sensor 1 is made in the form of a movable ferromagnetic element 10, an Ш-shaped magnetic circuit 11 with teeth (not shown) on the outermost rods, excitation windings 12 and readout windings 13-16.

Detection unit 3 contains amplitude detectors 17–20. The comparator block b is made in the form of comparators 21 and 22. The output bus 23 of the comparator 21 and the output bus 24 of the comparator 22 are the first and second control outputs of the converter, respectively. Switch 7 is configured as switch 25 and element OR 26. Outputs 27 of A / D converters 8 are information outputs of a converter. .

The functional converter 4 contains calculation blocks 28-33, adders 34-36, functional converter 5 — analog multiplication unit 37, adders 38 and 39, and analog division block 40.

The Converter operates as follows.

The number of turns of the first and second sections of the winding 12 is the same, so that the alternating current from source 2 creates equal magnetizing forces in each section.

Denote the coordinate of the center (middle) of the moving element 10, measured along the x axis of the controlled movements, through x, the step of applying the teeth of the magnetic circuit 11 through non-working transverse displacements of the moving element 10 along the y axis (backlash) through Su; the levels of variable voltages on the windings 13–16 through, the levels of the output voltages of the detectors I7–20 through Un-U4e, and their totality, G yp, ..., yoke through U (Figures 2 and 3).

Consider getting the output information of block 3 as well as the control

c

Q r

Q 5

50 5

0

45

information on the presence or absence of the movable element 10 in the conversion range for the case when the transverse displacements of the movable element 10 are missing (Su 0). In this case, the gaps B6 and ohm, measured along the axis y, are formed respectively by the upper edge of the movable element 10 (Fig. 1) with the ends of the teeth of the upper branch of the magnetic circuit 11 and the lower edge of the moving element 1 0 with the ends of the teeth of the lower branch of the magnetic circuit 11, equal to each other largest and have a nominal value of j0.

Approaching the movable element 10 to any tooth of the magnetic circuit 11 is characterized by an increase in the degree of filling the area between the end of this tooth by the ferromagnetic material (regardless of whether it belongs to the upper or lower branch of the magnetic circuit 11) and the opposite portion of the middle branch of the magnetic circuit 11. The magnitude of the magnetic flux passing on such a tooth, it increases, and if there is one on the tooth, from the windings 13-16, the value of the electrical signal induced in it increases accordingly (Fig. 2). The greatest overlap of the toothed ends, and therefore the highest levels of the output signals of the windings 13-16 and the proportional levels of the output voltages of the detectors 17-20, amplitudes are reached at X values equal to the coordinates of the teeth of the fixed magnetic circuit 11. With the moving element 10 removed from any of the teeth provided with the windings 13-16, the magnetic flux passing through this tooth weakens, respectively, the levels of the signal induced in the winding of this tooth and the output voltage are reduced about her detector 17-20.

The combination of the indicated areas of increase, transition through a maximum, and decrease in the dependences of the output voltages of the detectors 17-20 on the movements of the moving element 10 for Su 0 is shown in FIG. 2. The teeth of the upper and lower branches of the magnetic circuit 11 have the same shape and dimensions, which, taking into account the specified equality of the gaps formed by the movable element 10 with the teeth of the upper and lower branches of the magnetic circuit 11, causes, at O

equality of the signal levels U U16 and U (Cj 11th, respectively. Zero value of the X coordinate (lower limit of the conversion range) is related to the position of the moving element 10, for which the output levels of the windings 13 and 14, as well as the detectors 17 and 18 are equal in pairs to one drud the switch 25, as a result of which the reference output of the source 9 is connected to the input of the A / D converter 8, the output of which in this case also sets the overflow code.

Thus, the information set of the overflow code of the A / D converter 8 and the unit voltage

Goma U13 U

-44

U, 7

Top 23, the proposed converter 23

The xi of the conversion range is tied to the position of the moving element 10, for which the magnitudes of the output signals of the windings 14 and 15, as well as the detectors 18 and 19 U are equal in pairs

44

U

tf

i) B and „

For

Certainly, sensor parameters 1 provide the position x2 (Fig. 2).

The switching state of the switch 25 is determined as follows. If its control input is subjected to a zero-level voltage, then the input of the A / D converter 8, which (for definiteness) is a parallel device, is connected to the output of the function converter 5, but if the control input of the switch 25 is affected by a unit-level voltage, to the input of the ADC 8 is connected to the output of the source 9. When the movable element 10 is moved to the left outside the range of the displacement conversion (x "0), then)

U

15

the output of the comparator 21 is set to the voltage of the unit level, and the output of the comparator 22 is the voltage of the zero level. At the same time, a high voltage level from the output of the comparator 21 acts through the OR element 26 on the control input of the switch 25. Then the reference output of the source 9 is connected to the input of the ADC 8, the voltage at which is chosen to be much greater than the upper limit of the conversion range of the input voltage AC 8, and at the output of the ADC 8, an overflow code is set containing units in all bits.

When the movable element 10 is moved to the right outside the range of the displacement conversion (),

and"

U Ut-j, the output voltage of the comparator 21 is set to zero voltage, and the output of the comparator 22 is the voltage level of the unit level, the Output voltage of the unit level of the comparator 22 through the OR 26 element acts on the control

-

.

15

20

signals the output of the movable element 10 to the left beyond the range of the conversion of interlace, and the combination of the overflow code of the A / D converter 8 and the voltage level of the bus 24 to the output of the movable element 10 from the conversion to the right. The presence in these cases at the output of the ADC 8 overflow code eliminates the possibility of the device issuing false, but similar to reliable information.

When the center of the moving element 10 is in the conversion range of 25 displacements, U1S, U, 0 s, and the output voltages of the comparators 21 and 22 have zero levels acting through the OR 26 element on the control input of the switch 25, which causes the connection to the ADC input 8 of the output of the functional converter 5. At Jo 0, the voltage U (o (X) and 2o (X) and unambiguously corresponds to the coordinate of the moving element 10 (Fig. 2). With an off-shift of the moving element 10 0 "O up, the magnitude of the signal induced in the winding 16, and the voltage value, lower aemogo output from the detector 20 increases and the signal level in the windings 13-15 and their respective output voltages of detectors 17-19 are reduced (FIG. 3).

With non-working displacements

35

40

45

element 10 S. 0 signals in about

50

the coils 13-15 increase in comparison with their levels corresponding to the absence of idle displacements, and the signal in the winding 16 is attenuated. The magnitude of the output voltage of each of the detectors of block 3 is directly proportional to the level of its output signal.

The appearance of non-working transverse displacements, changing the size of the signals in the windings 13-15, does not change the coordinate of the projections of the center of the moving element 10 for its positions at which the signal levels of the windings of adjacent teeth of the lower branch of the magnetic circuit 11

are equal to one another, i.e. of equality

and „() U4f (X-0);

(X hg) 0, (X hg) are valid and there are cases of Su 0 0.

Since backlash does not affect the character of (qualitative) increase and decrease of the function U (X), the following ratios are maintained throughout the entire range D, between the output voltages of the detectors 17-19.

  and (8. if X 0;

U, 7 Uig, if X 0;

U (8, 7, U1B t U19, if x.

) in U, 9, if X x,

1q U (8 And p, if X hg.

Consequently, both in the presence and in the absence of idle displacements in the case of moving the movable element 10 to the left beyond the conversion range, the output of the comparator 21 is in one, and the output of the comparator 22 is in the zero state; when moving the movable element 10 out of the conversion range to the right, the output of the comparator 21 is in the zero state, and the output of the comparator 22 is in one state; when the movable element 10 is outside the LO range, the unit level control signal from the output of the OR 26 switch 25 connects the reference output of source 9 to the input of the A / D converter 8, the output of which overflow code is set.

When, for any (- 00 00), the center of the movable element 10 moves within a predetermined conversion range, a zero-level voltage is set on buses 23 and 24, and a switch 25 connects to the input of ADC 8 an output of the second function converter 5.

Consider the operation of the Converter, when the movable element 10 is located in the operating range.

The maximum possible signal level of any of the detectors 17-20 is denoted by Um (), then the output voltages of the detectors 19 and 20 are represented in dimensionless form as the ratio

2i- u ", 4t uzo / iv

In addition, (X / Xg) is the relative displacements of the movable element 10 (Fig. 4).

0

five

0 of

Q

The count of a pair of values of u (q jU2o of the levels of output voltages of the detectors 19 and 20 unambiguously determines the relative H x and the absolute X xy coordinates of the moving element 10 on the axis of controlled movements.

The l, chg values obtained as a result of the block detecting the 3 output voltages of the windings 15 and 16 are further used as dependency arguments reflecting the established uniqueness of the connection fx (i g) (Fig. 5), which should be approximated by fractional rational expressions with respect to one of the quantities J7,, with parameters depending on the other of the quantities fq

IT

35

x

i

5 where a

(one);

V

one

B | - dimensionless coefficients of approximation, which are functions of g PJ I are dimensionless constant exponents of powers, respectively, in terms of the numerator and denominator of the approximating function;

m is the number of terms in the numerator;

n is the number of terms in the denominator

Dependencies a; (d), b, (Ј2) are represented by polynomials

™; . ".

-ЈьЦ1 3

with constant approximation parameters

matsii a

R

 J

q (independent of Ј),

Approximation of the function of two variables x (implemented by functional converters 4 and 5, with m, n | 2; p4 q1 1; pr q q O, b, 0, i.e. the indicated expressions of the approximating function and coefficients a

one

specify

with as follows: to

a, + b2 CW

a4 a (g + 5

+ ar i

2

(one)

B b ,, f +

4-27

or taking into account the dimensions of the converted physical quantities

0 . to 5.2, (2,

where Ua, KQ,;

UQz Ka;

Qbgg;

K is the scale factor of the approximation parameters, which has the dimension of voltage and is chosen to be

um;

Ku is the scale factor of the voltage multiplication operation chosen to be (1 / U p,).

The values of the coefficients of the approximation contained in the expressions for a, a2, b2) are determined experimentally or by calculation at the stage of respectively manufacturing or designing converters. In the experimental determination of the approximation coefficients, the range of transformation of displacements is divided into a predetermined number of sections, using exemplary means of mechanical measurements (for example, a micrometric screw with an indicator), X values are fixed at the boundaries of the indicated sections of the conversion range and, ™ output voltages of unit 3 for a series of backlash values ots, varying within Dy. It is not necessary to measure the values of 6o themselves, since in the defined function x (Ј) the arguments are U1 (/ Um, U2o / Um and you need to know with sufficient accuracy the values of these arguments. Then the experimentally obtained set of correspondences X "- (U19 U $ 0) or X 2 using the least squares method is transformed into the form of a fractionally rational function (1). Obviously, the ratio Јx C 2, ($ 4 0) MB 0) 1, where H, ("O) fЈj ((u O) is included in the approximating dependence Јх (Ј) as a special case.

The first functional transducer 4 forms the voltages included in the expression (2) as functions of the argument U2orp

Uq, "Ka, K (a" 2V + a, 2O

"but

, € OCH „

 Vm

+ ia (, FR1a; C3)

-Ti

.R,-.

 Ka K gg11 + a ")

L2

and „. () Pil and

J “Un

n (- & yy

W

-V

 ka k (l21g +) (5)

five

0

five

0

Ub2l Kb22.

Levels Ia „, Ua (1,

and,

21 iagg

5 i

Ub2,, and "known by experimental or calculated data, are set (reproduced) at the installation outputs of the source 9.

Each of the blocks 28-33 of the calculations implements a continuous function of three variables (Fig. 6, the indices of d 28-33 correspond to the positions of the blocks 28-33 of the calculations)

„, -,.„ L.

where Ur is the output voltage of gd

block calculations;

Uri is the voltage applied correspondingly to ig2, correspondingly to its first,

the second and third entrances; Mj, are given exponents.

The output voltage of the detector 20 and the voltage of the installation outputs of the source 9 are diluted to the inputs of blocks 28-33 as follows:

0

U 20

and

 U2 2. b.

 and and

29, g

29.3

 iz; ZZZ;

Ua ,, -, (

and

Oil

them.

one

five

0

five

yag, im.,; Uo, zi u ,. "; h2 (u, 2l.;

Ub22. U ", 1

In addition, are set

M-26 R,

M

14

 . MZO p "1;

m

uh

  ; M32. qa (

M

53

q

Then, at the outputs of the adders 34-36, relations (3) - (5) are realized and the output voltages are allocated respectively

U, + Ua,;

and.

B5

U

aa U36

and, 6

g

These voltages are applied to the control inputs of the second function converter 5: voltage to

the input of the block 37, the voltage U, U36 - to the inputs of the terms of the summers 38 and 39, respectively. The block 37 allocates the voltage level

U37 Keya, and 19 lUKa, - KG

- Ka, (tft) ,.

At the output of the adder 38 is formed voltage

U3a U37 + U35, Uw + Uq ±

 , (H, + a2 (2), incoming to the input of the dividend block 4 division.

The output of the adder 39 is released voltage

U

ze

 U, o + U "+ U,

E6

, + sr (g)

nineteen

acting on the input of the divider unit 40 division, the output signal of which is equal to

S.ii kljL ± 2i (lЈl

"40

TO

ai

Uw v

- - - "(

39

3 + 4

where Cl is the scale factor of the voltage division operation, having the dimension of voltage.

Choosing for definiteness Ka Ka Um, it can be seen that the value obtained at the output of the second functional transducer 5 is the implementation of dependence (2)

i40 and, og,, "d) | - x s

t

X,

S const is the coefficient of proportionality (sensitivity by controlled displacement), independent of transverse displacements. When Xp switch 5

provides the electrical connection of the output of the second functional converter 5 to the input of the A / D converter 8, which outputs a binary code at the output 27, the values of which are proportional to the level of the U, Q Ux signal 8 converted by the A / D 8, i.e. when the center of the moving element I0 is located within the conversion range, the output code of the device is proportional to the X coordinate and its value does not depend on the magnitude of the lateral displacements 8c, since the U value is spared from this dependence

made in the form of an--shaped magnet of a ground wire, with three teeth; yes, on each of the outermost rods, an excitation winding, made in the form of two sections, located on the basis of the Ш-about a different magnetic conductor on both sides of the central rod, and connected to the source voltage, a movable ferromagnetic element located on the central rod, the first read winding located on the middle tooth of the upper pin of the W-shaped magnetic core and connected to the input of the first amplitude detector, the second, third and the fourth read winding, located on the three teeth of the lower H-shaped magnetic core and connected respectively to the inputs of the second, third and fourth amplitude detectors, the outputs of the second and fourth amplitude detectors are connected to the non-inverting inputs of the first and second separators, respectively, the source of the reference voltage, A first functional converter, an analog-digital converter, is al-a-to-switchboard, characterized in that, in order to increase the converter's accuracy and reliability, When the limits of the conversion range are entered, a second functional converter is entered into it, the output of the first amplitude detector is connected to the first input of the first functional converter, the output of the second amplitude detector is connected to the first input of the second functional converter, the output of the third amplitude detector is connected to the inverting inputs of the first L of the second comparator, outputs which are the control outputs of the converter and are connected to the control inputs of the switch, the first source output the reference voltage is connected to the first information input of the switch, and the second output is connected to the second input of the first functional converter, the output of which is connected to the second input of the second functional converter, the output of which is connected to the second inUL (g) - SX switch input, you ..... .-. . "Ri-XA rt r / - -Mn / -i- / 4Tir-s with-ГЧЛГТ ТТТЛТЛ f Q TT QTTfV

Noah binary code ADC 8, I

Claims (1)

Formula of Invention | The displacement transducer to the code containing the transformer sensor, the stroke of which is connected to the input of an analog-to-digital converter, the output of which is the information output of the converter. 0 five 0 25 thirty 35 40 45 ™ made in the form of an U-shaped magnetic conductor, with three teeth; yes, on each of the extreme rods, an excitation winding, made in the form of two sections, located on the basis of the U-shaped magnetic conductor on both sides of the central rod, and mobile ferromagnetic element located on the central rod, the first reading winding located on the middle tooth of the upper pin of the W-shaped magnetic core and connected to the input of the first amplitude detector, second, third and the fourth read winding, located on the three teeth of the lower H-shaped magnetic core and connected respectively to the inputs of the second, third and fourth amplitude detectors; the outputs of the second and fourth amplitude detectors are connected to the non-inverting inputs of the first and second parameters, respectively, the source of the reference voltage, The first functional converter, analog-digital converters at-a-to-switch, characterized in that, in order to increase the accuracy of the converter and the reliability of the converting the limits of the conversion range, a second functional converter is inserted into it, the output of the first amplitude detector is connected to the first input of the first functional converter, the output of the second amplitude detector is connected to the first input of the second functional converter, the output of the third amplitude detector is connected to the inverting inputs of the first l of the second comparator, outputs which are the control outputs of the converter and are connected to the control inputs of the switch, the first output source and the reference voltage is connected to the first information input of the switch, and the second output is connected to the second input of the first functional converter, the output of which is connected to the second input of the second functional converter, the output of which is connected to the second information input of the switch, vyri-XA rt r / - Mn / -i- / 4Tir-s with - GLPGTTTLTL f Q TT QTTfV the stroke of which is connected to the input of an analog-to-digital converter, the output of which is the information output of the converter. darf ъ у 2 у  j ogp : $ P th: t P  V  R L / L.ii w; H 2 epf B 0 P DG  g v t V / S / fl " ЈJ lZ P  / TTGLi ; Th 2221ZZZ,  five/ / z Wl H " J 90 76551