RU51725U1 - MOVEMENT CONVERTER - Google Patents

Abstract

The invention relates to the technical means of measuring the conversion of displacements into electrical signals using inductive sensors. It can be used in control systems for moving objects, in technological equipment. The technical result of its action is characterized by an increase in conversion accuracy, expressed in a decrease in dynamic error. The converter comprises a readout unit, an alternating voltage source, a zero potential bus, a comparator, a first single vibrator, a division unit, a subtractor and a reference voltage source, the readout unit including a differential inductive sensor with an armature and two series-connected operating windings forming a winding pair, and also a resistor connected in series with the winding pair, the first extreme output of the winding pair is connected to the first output of the AC voltage source and to the delhi input divider unit, and its second extreme terminal - to the first input of the comparator and one of the terminals of the resistor, the other terminal of which, together with the second terminal of the AC voltage source is connected to the zero potential bus and the second input of the comparator, the direct output of the comparator is connected to the input of the first one-shot, the output the division unit is connected to the input of the reduced subtractor, and the output of the reference voltage source is connected to the input of the subtracted subtractor. A second one-shot is introduced into the converter, to the input of which the inverted output of the comparator is connected, the outputs of the first and second one-shots being combined, the middle output of the winding pair connected to the input of the dividend, and the combined output of the first and second one-shots to the synchronizing input of the division unit. The pulses that control the selection of the readable informative signal and the receipt of its relationship to the readable compensation signal in the division unit synchronize the operation of this unit in each half-cycle of the alternating voltage. As a result, the error due to the presence of a deviation of the coordinates of the moving armature from a position that corresponds to the moment of each previous sample of read signals is halved.

Description

The invention relates to the technical means of measuring the conversion of displacements into electrical signals using inductive sensors. It can be used in control systems for moving objects, in technological equipment containing controlled moving objects. Known transducer containing a reading unit, which includes a differential inductive sensor with a magnetic armature and two working windings, as well as two compensation windings and four resistors. The first branch of the reading unit is formed by the serial connection of the first working winding, the first resistor, the second working winding, the second resistor; the second branch of the reading unit is formed by the serial connection of the first compensation winding, the third resistor, the second compensation winding, the fourth resistor. The converter also contains an alternating voltage source with two terminals, one of which is connected to the first extreme terminals, and the other to the second extreme terminals of both branches of the readout unit and to the bus of zero potential. In addition, this converter includes a comparator, a single vibrator, two sampling-storage devices (UVC) and a division unit.

The findings of the second resistor are connected to the inputs of the comparator, the direct output of which is connected through a single-vibrator to the control inputs of the first and second UHF. The average output of the first branch of the reading unit is connected to the information input of the first I / O, and the average output of the second branch is connected to the information input of the second I / O. The outputs of the first and second UVC are connected respectively to the inputs of the dividend and divider of the division unit [1]. This converter has the ability to compensate for inoperative changes in the amplitude and frequency of the alternating voltage supplying the reading unit.

The disadvantage of this converter is the low accuracy and the presence of a corresponding dynamic error due to the accumulation of discrepancies between the position of the armature at the time of the next sampling (discretization) of the read primary information and its position at the time of the next act of sampling, because there is an inter-sampling time period with a duration determined by the period of the alternating supply voltage, the output level of the converter is not updated.

In addition, this converter has a limited scope, since it is not able to measure displacements in different (positive and negative)

subbands and generate the corresponding output signals of different polarity.

In terms of technical nature, the displacement transducer containing a reader, an alternating voltage source, a zero potential bus, a comparator, a single vibrator, two UVCs, a division unit, a subtracter, and a reference voltage source is closest to the one proposed in this application. The reader, in turn, contains a differential inductive sensor with a magnetic armature and two series-connected working windings forming a winding pair, as well as two series-connected compensation windings and two resistors. The first extreme terminals of the winding pair and the pair of compensation windings are connected to the first output of the AC voltage source. One of the terminals of the first resistor and the first input of the comparator are connected to the second extreme terminal of the winding pair, and one of the terminals of the second resistor is connected to the second extreme terminal of the pair of compensation windings. Other conclusions of the first and second resistors are connected to the bus of zero potential and the second input of the comparator. The direct output of the comparator through a single vibrator is connected to the control inputs of the first and second I / O. The average output of the sensor’s winding pair is connected to the information input of the first UVC, and the average output of the pair of compensation windings is connected to the information input of the second UVC. The outputs of the first and second UVC are connected to the inputs of the dividend and divider of the division unit, the output of which, in turn, is connected to the input of the reduced subtracter, and the output of the reference voltage source is connected to the input of the subtracted subtractor [2]. Like the above-mentioned analog device [1], this converter is able to compensate for inoperative fluctuations in the amplitude and frequency levels of the alternating voltage supplying the reading unit.

The disadvantage of this Converter, taken as a prototype of the proposed technical solution, is the low accuracy due to the presence of a significant dynamic error in the conversion of displacements. This error is manifested when the speed of the observed object, to which the sensor armature is attached, in each time interval between the moments of adjacent samples of readable informative signals; This time period is determined by the length of the period of the alternating voltage supplying the reading unit. Here, the output signal level of the converter is tied to the moment of the previous sampling (discretization) and does not take into account changes in the magnitude of the read signals occurring due to armature shifts during time between adjacent time samples.

So, at the frequency of the AC voltage reading unit, the order is (5 ... 10) kHz (which corresponds to the period T of the order (10 ^-4 ... 2 · 10 ^-2 ) s), the armature speed υ = (5 ... 10 ) cm / s, conversion range ± x _r = ± 2.5 mm the reduced dynamic error caused by deviations of the armature from the position that corresponded to the time of the previous sample of readable informative signals is characterized by the values

γ _∞ = υT / x _r = (0.2 ... 0.8)%,

which has the most basic error of the converter as a whole.

The technical result is to increase the accuracy of the conversion of displacements by reducing the dynamic error (while providing compensation for non-working changes in the amplitude and frequency of the alternating voltage supplying the reading unit).

The technical result is achieved in that a displacement transducer comprising a reading unit, an alternating voltage source, a zero potential bus, a comparator, a first one-shot, a division unit, a subtractor and a reference voltage source, wherein the reading unit includes a differential inductive sensor with an armature and two in series connected by working windings forming a winding pair, as well as a resistor connected in series with the winding pair, the first extreme terminal of the winding pair is connected to to the output terminal of the AC voltage source and to the input of the divider of the division unit, and its second extreme output to the first input of the comparator and one of the terminals of the resistor, the other output of which, together with the second output of the AC voltage source, is connected to the zero potential bus and the second input of the comparator, direct output the comparator is connected to the input of the first one-shot, the output of the division unit is connected to the input of the reduced subtracter, and the output of the reference voltage source is connected to the input of the subtracted subtractor, the second dnovibrator, which is connected to an input of the inverse output of the comparator, wherein the outputs of the first and second monostable multivibrators are connected with each other, the average output of the winding pair is connected to the input of the dividend, and the combined output of the first and second monostable multivibrators - dividing the clock input to the block.

The set of distinctive features of the claimed device is capable of achieving the technical result inherent in this utility model.

Figure 1 shows a block diagram of the inventive displacement transducer, figure 2 is a functional diagram of a division unit, figure 3 is a timing diagram of the formation of pulses of operation control

obtaining the relationship of informative and compensatory read signals.

The displacement transducer (Fig. 1) contains a reading unit 7, an alternating voltage source 2, a zero potential bus 3, a division unit 4, a subtractor 5, a reference voltage source 6, a comparator 7, the first 8 and second 9 single-vibrators. Block 7 includes an armature 10, a first 77 and a second 72 working windings, the series connection of which forms a winding pair, as well as a resistor 13; the armature 10 and the winding pair form a differential inductive sensor. Anchor 10 is attached to a controlled moving object (not shown).

The first extreme (left in Fig. 1), middle and second extreme (right) conclusions of the winding pair are marked in the diagram of Fig. 1 with the symbols a, b, c, respectively, combining the outputs of the first 8 and second 9 single-vibrators - through d.

The resistor 13 is connected with a winding pair of block 7 in series. The average output b of the winding pair is connected to the input of the divisible unit 4. The first (right in FIG. 1) output of the source 2 is connected to the first extreme terminal d of the winding pair, as well as to the input of the divider of unit 4.

The output of block 4 is connected to the input of the decremented one, and the output of source 6 is connected to the input of the subtracted subtractor 5, the output of which is at the same time the general output of the displacement transducer. The second extreme terminal from the winding pair, connected to one of the terminals (right in FIG. 1) of the resistor 13, is also connected to the first (upper in FIG. 1) input of the comparator 7, and the other (left in FIG. 1) terminal of the resistor 13 is connected with the second (right in FIG. 1) output of source 2, bus 3 and the second (lower in FIG. 1) input of comparator 7. The direct (upper in FIG. 1) output of comparator 7 is connected to the input of the first one-shot 8, and the inverse (lower ) the output of the comparator 7 - with the input of the second one-shot 9. The outputs of the one-shots 8, 9 are interconnected, as well as synchronized block input 4.

Block 4 (figure 2) consists of a repeater - inverter 14, a sampling-storage device (UVX) 15, a voltage-to-code ratio shaper 16, an analog-to-digital converter (ADC) 17 and an input amplifier 15. The ADC 17 has a binary code output 19 level (absolute value) of its input voltage and an output of 20 significant bits, displaying the sign of this input voltage of the ADC 17.

The information input of the repeater - inverter 14 and the input of the amplifier 18 are at the same time the inputs of the divisible and divisor of block 4 as a whole, and the interconnected control input of the UVX 15 and the synchronization input of the ADC 17 represent the common synchronization input of block 4. The output of the repeater - inverter 14 is connected to the information input of the UVX 15, the output of which is connected to

the analog input of the shaper 16. The output 20 of the ADC 17 is connected to the control input of the repeater - inverter 14, and the output 19 of the ADC 17 is connected to the code input of the shaper 16.

The implementation of the repeater-inverter 14 is presented in the description of the known transducer to the code [3] (item 16, figure 2). The driver 16 is a known circuit for incorporating a digital-to-analog converter into the feedback circuit of an operational amplifier [4, p.234-235, Fig. 9.4, b]; the indicated circuit implements a division mode (with a known proportionality coefficient) of the voltage supplied to its analog input by the value of the code supplied through its code input. The implementation of the ADC 17 with the output parallel binary code is also quite well known [4, p.239-251]; the next working act of the ADC 17 is triggered by a synchronizing pulse received at the corresponding synchronization input of block 4. The amplifier 18 is designed to normalize the levels of variable voltages supplied to the input of the divider of block 4. Below, for definiteness, the use of ADC 17 with a two-digit input voltage range of converted voltages (has subranges of negative and positive values), as well as the use of an amplifier 18 operating in inverter mode (with a negative conversion coefficient).

The inventive Converter operates as follows.

The electrical branch of block 7, consisting of a winding pair of a differential inductive sensor and resistor 13, is flooded from source 2 with an alternating voltage u _P with an amplitude U _{m of} period T:

u _P = U _m sinωt,

where ω = 2π / T is the circular frequency; T-time.

Changes in the coordinate X of the armature 10 of the differential inductive sensor, counted along the axis of the measured displacements x, cause different increments of the inductances L ₁ , L _2, respectively, of the first 11 and second 12 working windings. Within the ± x _r range of the displacement transducer, such diverse increments as follows affect the values of these inductances:

L ₁ = -λX + L _δ , L ₂ = λX + L _δ ,

where λ is the steepness of the change in the inductance of the working winding caused by a change in the position of the armature 10 on the x axis; L _δ is the balanced inductance of the working winding, corresponding to the zero value of the coordinate X. When the armature 10 moves at a speed υ from the initial position X ₀ , the X coordinate is determined by the sum (X ₀ + υt).

The total inductance of the winding pair

L ₁ + L ₂ = 2L _δ ,

unlike its components L ₁ , L ₂ , the function of the X coordinate and velocity υ is not.

An alternating current flows in the electrical branch of block 1

i = I _m sin (ωt-φ)

with an amplitude of I _m and a phase shift relative to an alternating voltage u _{P of} φ = arctgQ;

Q = ω (L ₁ + L ₂ ) / (r ₁ + r ₂ + R),

where r ₁ , r ₂ are the active resistances of the first 11 and second 12 working windings, respectively; R is the active resistance of the resistor 13,

I _m = U _m / ((r ₁ + r ₂ + R) (Q ² +1) ^1/2 )

The values of the output alternating voltages of block 1 — the read signals taken from the conclusions a, b, c are counted relative to the zero potential of the bus 3.

The compensation read-out signal - voltage is removed from the first extreme terminal of a winding pair

u _a = (L ₁ + L ₂ ) i '+ (L ₁ + L ₂ )' i + (r ₁ + r ₂ + R) i,

where i '= di / dt = ωI _m cos (ωt-φ);

(L ₁ + L ₂ ) '= d (L ₁ + L ₂ ) / dt = d (2L _δ ) / dt = 0,

i.e

u _a = 2L _δ i '+ (r ₁ + r ₂ + R) i.

Co the middle output b of the winding pair is taken informative read signal - voltage

u _in = L ₂ i '+ L ₂ ' i + (r ₂ + R) i,

where L ₂ = dL ₂ / dt = d (λ (X ₀ + υt) + L _b / dt = λυ,

i.e

u _in = (λX + L _δ ) i '+ (λυ + r ₂ + R) i.

Co the second extreme output from the winding pair is removed control read signal - voltage u _c = Ri.

The state of the outputs of the comparator 7 is determined by the level of the signal u _c supplied to its first input; at the second input of the comparator 7, the zero potential of the bus 3 is constantly maintained. If the voltage is and, positively, then at the direct output of the comparator 7 a signal u _{7 of a} high level U corresponding to a logical unit is allocated; otherwise (negative or zero value and _c ) at the direct output of the comparator 7, a signal u _{7 of a} zero level corresponding to a logical zero is extracted (Fig. 3). For the same polarities of the signal u _c on the inverse output of the comparator 7 are allocated: when

positive values u _c - zero output signal level corresponding to logical zero; at negative or zero values u _c - high level U of the output signal u ₇ corresponding to a logical unit.

Any of the one-shots 8-9 generates an output pulse of short duration Δτ≪T [2] when a positive difference (from zero to a high level) of its input signal is exposed to the input of this one-shot: for voltage 8, the voltage is ₇ ; for the second 9 one-shot - voltage . Such differences occur at the outputs of the comparator 7 with the passage of voltage u _c - and, accordingly, current i = u _c / R - through a zero value.

Positive voltage drops u ₇ at the direct output of comparator 7 occur at time t _2k-1 , (k is the integer index of the observed voltage period u _П ), corresponding to zero current value i and a positive value of its time derivative i ', and positive voltage drops on the inverted output of the comparator 7 occur at time t _2k , corresponding to the zero value of current i and the negative value of its time derivative i '.

At moments t _2k-1 , t _{2k, the} formation of output pulses of the first 8 and second 9 single vibrators, respectively, is initiated:

Pulse signals are received from the output of the first 8 and second 9 single-vibrators combined at point d to the synchronizing input of block 4

they follow each other at intervals of T / 2 duration - twice as often as the signals of separately taken sequences u ₈ , u ₉ , i.e.

where (l is the integer index of the observed half-cycle of the voltage u _П ; l = 1, ..., 2к-1, 2к, ....

The moments t _{l are} determined on the basis of the fact that the value of current i is zero, by the condition

i = 0, sin (ωt ₁ -φ) = 0,

whence it follows that

t _l = (π (l-1) + φ) / ω) = π (l-1) / ω + t _CM ,

where t _СМ = φ / ω) is the temporary displacement between the passage of current i and voltage u _П through a zero value with the same signs of their time derivatives. In particular, with l = 1, the equality t _CM = t ₁ holds (Fig. 3). In addition, equality

ωt _l -φ = π (l-1) = 0

for l = 1, it implies the positivity of the time derivative of the current i '(t ₁ ) = ωI _m cos (ωt ₁ -φ) = ωI _m cos0> 0.

During the action of pulses u _d informative u _in and compensation u _a read signals have the following meanings:

u _in (t _l ) = L ₂ i '(t _l ) + (λυ + r ₂ + R) i (t _l ) = ωI _m L ₂ cos (ωt _l -φ) = ωI _m (λХ + L _δ ) cosπ (l-1);

u _a (t _l ) = 2L _δ i '(t _l ) + (r ₁ + r ₂ + R) i (t _l ) = 2ωI _m L _δ cos (ωt _l -φ) = 2ωI _m L _δ cosπ (l -1), moreover

u _a > 0, u _in > 0 for cosπ (l-1) = 1,

u _a <0, u _at <0 for cosπ (l-1) = - 1.

The alternating voltage u _{a is} inverted and, with the aim of introducing the ADC 17 into the boundaries of the input range, it changes in level with the amplifier 18, at the output of which a signal is generated

u ₁₈ = k ₁₈ u _a ,

where k ₁₈ <0 is the conversion coefficient of the amplifier 18.

The absolute value of the signal u ₁₈ at the output 19 is represented in parallel as a binary code N ₁₉ , formed at the rate of pulses u _d to the synchronizing input of block 4. Up to a small Lee value, the prices of the lowest code bit

The state of the output 20 is determined by the state of the sign discharge of the ADC 17, which, in turn, corresponds to the sign of the voltage converted by the amplifier 18:

The sign of the conversion coefficient to _{14 of the} repeater-inverter 14 is determined depending on the output level 20 (similar to the well-known condition [3]):

that given

u _a (t _l ) = 2ωI _m L _δ cosπ (l-1), 2ωI _m L _δ > 0

is equivalent to

k ₁₄ = -cosπ (l-1).

The output voltage of the repeater - inverter 14 has the form:

u ₁₄ = k ₁₄ u _in = -cosπ (l-1) (ωL ₂ I _m cos (ωt-φ) + (λυ + r ₂ + R) sin (ωt-φ)).

At the output of the UVX 15, within the duration of each half-cycle of the voltage u _П with reference to the moments t _l , a signal is formed

u ₁₅ = u ₁₄ (t _l ) = K ₁₄ u _in (t _l ) = - cos ² π (l-1) ωI _m L ₂ = -ωI _m (λX + L _δ ).

Shaper 16 implements the function of obtaining the ratio of the analog divider u ₁₅ to the binary code N ₁₉ and allocates voltage (at the same time, the output of block 4 as a whole) at its output

u ₁₆ = u ₄ = -N _m u ₁₅ / N ₁₉ = U _Г ωI _m L ₂ / (2 | k ₁₈ | ωL _δ I _m ) = U _M (λX + L _δ ) / L _δ

where N _m - the maximum value of the output code of the ADC 17, which corresponds to the corresponding level of the output signal of the amplifier 18 U _r = N _m Δu;

U _M = 0.5U _G / | k ₁₈ | - the scale factor of the division operation.

As a result of a periodic change in the sign of the coefficient k _{14, the} signal u ₁₈ generated by the UVX 15 in each half-cycle of the voltage u _P does not change its polarity and does not create corresponding significant voltage drops at the analog input, 16 is formed, which eliminates the possible uncertainty at its output during operation pulses that control the sampling produced by the UVX 15.

Source 6 generates a constant voltage, set equal to the value u ₆ = U _M , and at the output of the subtractor 5, which is the overall output of the claimed device, a signal is generated

u ₅ = u _OUT = k ₅ (u ₄ -u ₆ ) = k ₅ U _M (l / L _δ ) X = K _PR X,

where k ₅ is the scale (weight) coefficient of the subtraction operation; this coefficient is a parameter of the subtractor 6 [4, p.27-30, Fig. 1.9, a, 1.10, a];

K _PR = k ₅ U _M (λ / L _δ ) is the total conversion coefficient of displacements implemented by the proposed device.

The signal u _{OUT is} proportional to the measured coordinate of the armature 10 and, together with it, the coordinate of the moving controlled object, and its level does not depend on inoperative fluctuations in the amplitude and frequency of the alternating voltage u _P supplying unit 4, i.e., the proposed

the device, to the same extent as its prototype, neutralizes these non-working vibrations.

Compared with the device - the prototype [2] (and the device is an analogue [1]), the claimed device is characterized by a significant reduction in the dynamic error of conversion of displacements. This is due to the implementation of the claimed device using the newly introduced features of its construction, which provided conversion with a doubled sampling rate of the readout measuring signals.

If, for the prototype device, the reduced dynamic error due to the accumulation of deviations of the armature of the differential inductive sensor from the position corresponding to the moment of the previous sample t _k , by the time of the next sample t _{k + 1} is determined by the duration T of the alternating voltage period supplying the reading unit, and amounts to then for the inventive device with the same conversion range (± x _r ), the error of this type is determined in relation to half the sampling interval t _{l + 1} -t _l = T / 2 and the expression as

That is, the dynamic error in the conversion of displacements is due to deviations of the armature of the differential inductive sensor from the position corresponding to the time of the previous sample of readable measuring signals within the oversampling interval for the claimed device is halved compared to the error of this type, which characterizes the prototype device. So, for the values of the frequency of the alternating supply voltage of the order of (5 ... 10) kHz indicated in the introductory part of the present description, the armature speed of the order of (5 ... 10) cm / s, the range of transformed movements ± 2.5 mm , characterizing the actions of the proposed device, are (0.1 ... 0.4)% against the levels (0.2 ... 0.8)%, characterizing the action of the device - the prototype, and this increase in accuracy is achieved by implementing the newly introduced combination of features the claimed device.

Claims (1)

A displacement transducer, contents, a reading unit, an alternating voltage source, a zero potential bus, a comparator, a first one-shot, a division unit, a subtractor and a reference voltage source, wherein the reading unit includes a differential inductive sensor with an armature and two series-connected operating windings forming a winding pair as well as a resistor connected in series with the winding pair, the first extreme terminal of the winding pair is connected to the first output of the AC voltage source I also go to the input of the divider of the division unit, and its second extreme output - to the first input of the comparator and one of the terminals of the resistor, the other output of which, together with the second output of the AC voltage source, is connected to the zero potential bus and the second input of the comparator, the direct output of the comparator is connected to the input the first one-shot, the output of the division unit is connected to the input of the reduced subtractor, and the output of the reference voltage source is connected to the input of the subtracted subtractor, characterized in that a second one-shot is introduced into it, course of which the inverse output of the comparator is connected, and the outputs of the first and second monostable multivibrators are connected with each other, the average output of the winding pair is connected to the input of the dividend, and the combined output of the first and second monostable multivibrators - dividing the clock input to the block.