RU2326446C1 - Digital displacement transducer - Google Patents

Digital displacement transducer Download PDF

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RU2326446C1
RU2326446C1 RU2007113996/09A RU2007113996A RU2326446C1 RU 2326446 C1 RU2326446 C1 RU 2326446C1 RU 2007113996/09 A RU2007113996/09 A RU 2007113996/09A RU 2007113996 A RU2007113996 A RU 2007113996A RU 2326446 C1 RU2326446 C1 RU 2326446C1
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Russia
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amplitude
output
raster
input
displacement
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RU2007113996/09A
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Russian (ru)
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Борис Вульфович Цыпин (RU)
Борис Вульфович Цыпин
Евгений Александрович Ломтев (RU)
Евгений Александрович Ломтев
Евгений Алексеевич Мокров (RU)
Евгений Алексеевич Мокров
Владимир Борисович Цыпин (RU)
Владимир Борисович Цыпин
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Пензенский государственный университет (ПГУ)
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Abstract

FIELD: physics, measurement.
SUBSTANCE: digital displacement transducer relates to the field of automation and information equipment and is intended for the measurement of linear and angular displacement using scanning transformer transducers. The digital displacement transducer contains the following components connected in series: amplitude logical device (5), position code decoder (6), and reversible counters (7), as well as power supply (1) connected to the excitation winding of scanning transformer displacement transducer (2) and the input of interrogation pulse generator (5), the output of which is connected to the synchronisation input of amplitude logical device (5), voltage summator (4) is introduced to it, with the inputs connected to the two adjacent sense windings of scanning transformer transducer (2) and the output connected to the additional input of amplitude logical device (5).
EFFECT: increase in displacement measurement accuracy.
5 dwg

Description

The present invention relates to the field of automation and information-measuring equipment and can be used to measure linear and angular displacements using raster transformer sensors.
Known converters displacement in the code based on raster transformer displacement sensors [1]. Their common drawback is low accuracy, limited by the minimum achievable dimensions and the number of teeth of the magnetic system that can be provided during manufacture.
Of the known closest in technical essence is the displacement transducer to code based on raster transformer displacement sensors that implements the amplitude-logical method of processing the sensor output signals described in the monograph (Konyukhov N.E., Mednikov F.M., Nechaevsky M.L. Electromagnetic sensors of mechanical quantities. - M .: Mashinostroenie, 1987, pp. 173-175), the implementation of which for a sensor with four read windings is described in the same place on pages 228-231. A diagram of the displacement to code converter is shown in FIG. Figure 2 shows the General case of pairing two parallel raster grids to explain the principle of operation of the raster transformer displacement sensor. Figure 3 shows a diagram of changes in voltage amplitudes on the read windings of a raster transformer sensor when moving the movable element relative to the base.
The electronic unit (figure 1) contains a device for monitoring the integrity of the communication line 1, four raster transformer sensors 2, 3, 4 and 5 of the read winding of which are connected, respectively, to the four measuring channels 6, 7, 8 and 9, a diagnostic device 10, output which is connected to the inputs of the measuring channels, and the device 11 power sensors. The composition of each of the measuring channels 6, 7, 8, and 9 includes sequentially connected amplitude-logic device 12, a position code decoder 13, an account pulse generator 14, a counter 15, and a digital-to-analog converter 16. The diagnostic device 10 contains a generator of such a frequency 17 and a key 18, connected through a circuit And 19, a counter 20 and a decoder 21 connected to the control input of an analog switch 22, switching the output signals of the transformer 23. The primary winding of the transformer 23 is connected to the output of the device 11 power sensors 2, 3, 4 and 5. The device 11 power sensors, in turn, consists of a linearly varying voltage generator 24, a voltage-current Converter 25, the amplifier-corrector 26, loaded on the resistor 27, and the pulse generator polling 28.
The operation of raster transformer sensors is based on the coupling of two raster gratings. The strokes of the first lattice (Fig. 2) are plotted at an angle φ 1 to the abscissa axis with a step equal to λ 1 , and the strokes of the second are plotted at an angle φ 2 and have a pitch of λ 2 . The intersection points of the gratings form combination bands, which are a family of parallel lines with a step of τ. Thus, a scale is formed with the division price τ. In the sensor, one of the gratings is formed by a fixed gear ferromagnetic base (stator), and the second by a movable gear ferromagnetic element (rotor). In the grooves of the base are laid sections of the reading and field windings.
The magnetic flux developed by the sections of the field windings closes between the stator and the rotor through the tooth gap, crosses the read windings and induces an EMF in them, the magnitude of which is proportional to the magnetic conductivity of the sections of the magnetic circuit formed by the base, the movable element and the air gap between their teeth. Magnetic conductivity depends on the area of mutual overlapping of the teeth. When the relative position of the teeth of the base and the movable element of the sensor changes, a combination raster conjugation is formed, which leads to a change in the output signals on the read windings. The law of change in the amplitudes of the output signals on the read windings when moving the movable element relative to the base by x is sinusoidal, that is, amplitude modulation of the output signals appears, the frequency of which depends on the rate of change of the relative position of the teeth of the base and the movable sensor element.
Figure 3 shows the case for a raster transformer sensor 2 with four read windings and, accordingly, four voltages on them - U2.1, U2.2, U2.3 and U2.4. The period T of the voltage amplitude changes corresponds to one step of the tooth pairing. The period T is divided into a number of zones (in FIG. 3 there are eight of them - Z1, ..., Z8) with a step τ of raster conjugation. The zones differ from each other by the ratio of the amplitudes of the voltages on the read windings. For example, in zone Z3 (shaded in FIG. 3), U2.2> U2.3> U2.1> U2.4.
The electronic unit operates as follows. In the sensor supply device 11, a generator 24 generates a ramp voltage. Using a converter 25 and an amplifier-corrector 26, it is converted into a triangular current to power the field windings of the sensors 2, 3, 4, and 5. Rectangular voltages appear in the sensor read windings by integrating a triangular supply current in the sensor. The amplitudes of these voltages depend on the relative position in the sensors of the fixed gear ferromagnetic base and the movable gear ferromagnetic element, namely, the area of the mutual overlapping of the teeth. The pulse generator polling 28 generates a pulse at the time of the expected maximum voltage on the read windings of the sensors. On this pulse, the comparison device in the composition of the amplitude-logical device 12 produce a pairwise comparison of the amplitudes of the voltages on the read windings of each of the sensors. As a result of the comparison, the outputs of the comparison devices of the amplitude-logical device 12 appear logical zero or one signals. The encoder of the position code 13 converts the output code combination of the amplitude-logic device 12 into a three-digit binary code corresponding to the relative position of the stationary gear ferromagnetic base and the movable gear ferromagnetic element. The pulse generator of the count 14 generates pulses to the reverse counter 15 when moving from one zone to another, that is, when the code in the decoder 13 changes. The reversible counter 15 converts the pulses of the shaper 14. The digital-to-analog converter 16 converts the output code of the counter 15 into a DC voltage to enable operation with analog recording systems.
The integrity control device of the communication line 1 checks the communication lines of the windings of the sensors 2, 3, 4, and 5 with measuring channels 6, 7, 8, and 9. In the event of a break in one of the lines, the signal “Break” is issued. The diagnostic device 10 is periodically connected to check the operability of the measuring channels 6-9 when the sensors are turned off or in the case when there is no possibility to set the movement (sensors are installed on the product). Using the key 18 at the output of the diagnostic device 10, it is possible to obtain various combinations of voltage amplitudes corresponding to the output voltages of the sensors in different positions.
A disadvantage of the known displacement transducer to code based on raster transformer displacement sensors is low accuracy, limited by the minimum achievable dimensions and the number of teeth of the magnetic system that can be provided during manufacture.
The invention is aimed at eliminating this drawback.
This is achieved by the fact that in the displacement transducer into a code containing an amplitude-logic device connected in series, a position code decoder and a reversible counter, as well as a current source connected to the field winding of the raster transformer displacement sensor and the input of the polling pulse shaper, the output of which is connected to the input synchronization of the amplitude-logical device, an additional voltage adder is introduced, the inputs of which are connected to two adjacent windings for reading a raster an informator sensor, and the output to the additional input of the amplitude-logic device.
Figure 4 presents the structural diagram of the proposed transducer displacement in the code based on raster transformer displacement sensors. Figure 5 shows a diagram of the change in the amplitude of the voltages at the inputs of the amplitude-logic device when moving the movable element of the raster transformer sensor relative to the base.
The displacement converter into a code based on raster transformer displacement sensors contains a power supply source 1 of a raster transformer displacement sensor 2 with four read windings 2.1, 2.2, 2.3, and 2.4, an interrogation pulse shaper 3, a voltage combiner 4, an amplitude-logic device 5, a position code decoder 6 and a reversible counter 7. The output of the power supply current 1 is connected to the excitation winding of the raster transformer displacement sensor 2 and the input of the pulse shaper polling 3. The output of the polling pulse generator 3 is connected to the synchronization input of the amplitude-logic device 5. The read windings of the raster transformer displacement sensor 2 are connected to the inputs of the amplitude-logic device 5. Two adjacent read windings of the raster transformer displacement sensor 2, for example 2.1 and 2.2, or 2.2 and 2.3, or 2.3 and 2.4, or 2.4 and 2.1, are connected via a voltage combiner 4 to an additional input of the amplitude-logic device 5. The outputs of the amplitude-logic device 5 are connected through a position code decoder 6 with the input of the reverse counter 7.
All devices included in the displacement transducer in the code can be implemented as separate functional blocks. It is also possible to implement some nodes, for example, a power supply source 1, an interrogation pulse generator 3, a voltage combiner 4, an amplitude-logic device 5, a position code decoder 6 and a reverse counter 7, with software in a microcontroller equipped with comparators or analog-to-digital converters.
The translate to code converter works as follows. An AC signal (a sinusoidal waveform or another, for example, in the form of sawtooth or rectangular pulses), the power source 1 enters the excitation winding of the raster transformer displacement sensor 2. Voltages appear on the read windings of the raster transformer displacement sensor 2, the amplitudes of which depend on the position of the rod sensor at a given time. When moving the rod of the raster transformer displacement sensor 2, the voltage amplitudes on the read windings change according to a sinusoidal law, and the changes in the envelope of the amplitudes in the neighboring windings differ in the initial phase by the same angle. The voltages of any two adjacent windings add up in the voltage adder 4. Let voltage U2.1 = U cosx coswt, where U is the amplitude of the carrier frequency oscillation w, x is the measured displacement, and voltage U2.2 = Ucos (x + τ) cos (wt ) Then the output voltage of the voltage adder is 4 U4 = U cosx coswt + U cos (x + τ) cos (wt) = 2 Ucos (τ / 2) cos (x + τ / 2) cos (wt). The transmission coefficient of the adder voltage 4 is selected equal to 1 / 2cos (τ / 2). In this case, the amplitude of its output signal was equal to the amplitude of the signals on the read windings of the raster transformer displacement sensor 2. For example, when using a raster transformer displacement sensor with four read windings τ = π / 2 and the transmission coefficient of the voltage combiner 4 is chosen equal to
Figure 00000002
when using a raster transformer displacement sensor with three read windings τ = π / 3 and the transmission coefficient of the voltage combiner 4 is selected equal to 1, etc. The envelope U4 of the amplitude of the output voltage of the voltage combiner 4 is shown in FIG. The value of its initial phase is equal to the average value of the initial phases of the envelopes of the amplitudes of the input voltages of the voltage adder 4. As a result, each of the zones Z1, ..., Z8 is divided into two halves, that is, the step of the raster lattice is halved. A sign of the newly formed zones is also the ratio of the values of the envelope amplitudes: inside zone Z1 in the first half U2.1> U4, and in the second half U2.1 <U4; inside zone Z2 in the first half U2.2 <U4, and in the second half U2.2>U4; inside zone Z3 in the first half U2.3 <U4, and in the second half U2.3>U4; inside zone Z4 in the first half U2.4 <U4, and in the second half U2.4>U4; inside zone Z5 in the first half U2.1 <U4, and in the second half U2.1>U4; inside zone Z6 in the first half U2.2> U4, and in the second half U2.2 <U4; inside zone Z7 in the first half U2.3> U4, and in the second half U2.2 <U4; inside zone Z8 in the first half U2.4> U4, and in the second half U2.4 <U4.
The interrogation pulse generator 3 at a time corresponding to the maximum voltage value at the read windings of the raster transformer sensor 2 generates a pulse according to which the amplitudes of the input voltages are compared in amplitude-logic device 5. As a result of the comparison, the outputs of the amplitude-logical device 5 appear signals of logical zero or one. The decoder of the position code 6 analyzes the output signals of the amplitude-logic device 5, identifies the zones inside the raster step (Fig. 5) and generates a zone number code. The reversible counter 7 captures the code of the zone number and then incrementally increases or decreases it by one with each change in the code of the zone number.
The introduction of a voltage combiner 4 with appropriate connections allows to double the accuracy of measuring displacement using raster transformer sensors.
Information sources
1. Konyukhov N.E., Mednikov F.M., Nechaevsky M.L. Electromagnetic sensors of mechanical quantities. - M.: Mechanical Engineering, 1987.

Claims (1)

  1. A displacement transducer into a code comprising a series-connected amplitude-logic device, a positional code decoder and a reversible counter, as well as a current source connected to the excitation winding of the raster transformer displacement sensor and the input of the polling pulse generator, the output of which is connected to the synchronization input of the amplitude-logic device, characterized in that a voltage adder is inserted into it, the inputs of which are connected to two adjacent windings of reading a raster transformer th sensor output and the auxiliary input to the amplitude-logic device.
RU2007113996/09A 2007-04-13 2007-04-13 Digital displacement transducer RU2326446C1 (en)

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Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
КОНЮХОВ Н.Е. Электромагнитные датчики механических величин, Москва, Машиностроение, 1987, с.228-231. *

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