RU1779923C - Device for measuring motions of object - Google Patents

Abstract

The invention relates to a measurement technique. The purpose of the invention is to improve the accuracy of measurements at low speeds of movement of the object. The raster converter 1 generates four signals offset 90 ° from each other At the output of the analog switch 3, under the control of the quadrant determining unit 2, a triangular waveform is generated. An analog-to-digital converter 4 converts the amplitude of a triangular waveform into a positional code. The EXCLUSIVE OR element 5 together with the phase switch unit 6 form measuring pulses depending on the direction of movement of the object. The number of measurement pulses is counted by the pulse counter 8. 3 ill.

Description

1L

WITH

The invention relates to measuring equipment and can be used in automatic process control systems.

A motion measuring device is known comprising a raster converter and an interpolator.

A disadvantage of the device is the multiple conversion of the information signal, which reduces the accuracy of the measurement.

The closest technical solution to the invention is a device for measuring displacement, comprising a raster converter with four outputs, a quadrant for determining signals, four inputs of which are connected to the outputs of the raster converter, an analog switch, information and control inputs of which are connected respectively to the outputs of the raster converter and a quadrant detection unit; a pulse counting unit.

A disadvantage of the device is the lack of accuracy associated with errors in converting the slope of the sawtooth intermediate information signal into frequency.

The aim of the invention is to increase the accuracy of measurements at low speeds of movement of the object.

This goal is achieved in that the device for measuring the movement of the object, comprising a raster converter with four outputs, a quadrant for determining signals, four inputs of which are connected to the outputs of the raster converter, an analog switch.

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the information and control inputs of which are connected respectively to the outputs of the raster converter and the unit for determining the quadrant of signals, the pulse counting unit is equipped with an analog-to-digital converter, the input of which is connected to the output of the analog switch, an EXCLUSIVE OR element with an inversion, the outputs of which are connected to the two lower-order bits analog-to-digital converter, by a phase switch unit, the inputs of which are connected to the second low-order bit of the analog-to-digital converter and the output of This EXCLUSIVE OR with an inversion, a discrete switch, two information and four control inputs of which are connected respectively to the output of the phase switch block and the outputs of the quadrant signal determination unit, the outputs of the discrete switch are connected to two inputs of the pulse counter,

Figure 1 shows the functional diagram of the device; Figure 2 is a timing chart of the input and output signals of the quadrant for determining the signals and the output signal of an analog switch; in Fig.3 is a timing chart of the output signals of the elements of the device, providing the Formation and counting pulses of the converted signals.

The device contains a raster converter 1 with four outputs, a quadrant for determining the quadrant of signals, four inputs of which are connected to the outputs of the raster converter 1, an analog switch 3, information and control inputs of which are connected respectively to the outputs of the raster converter

1 and block 2 of determining the quadrant of signals, analog-to-digital converter 4 (ADC), the input of which is connected to the output of analog switch 3, element 5 EXCLUSIVE OR with inversion, the inputs of which are connected to the two lower-order bits of ADC 4, block 6 of the phase switch, whose inputs connected to the second low-order bit of ADC 4 and the output of element 5 EXCLUSIVE OR with inversion, discrete switch 7, two information and four control bypasses of which are connected respectively to the outputs of block 6 of the phase switch and the outputs of the block

2 determine the quadrant of the signals, and a pulse counting unit 8, the two inputs of which are connected to the outputs of the discrete commu- tor / 7.

The functional diagram of a possible implementation of the raster converter 1 (see Fig. 1) contains a modulator 9,

which is made in the form of an optically coupled light source, a measuring raster mechanically connected with a moving object and equipped with a scale

with a constant step of strokes, and a stationary raster having four sections of strokes offset by a quarter of the step of the measuring raster, four photodetectors 10-13, which are installed behind

raster conjugation so that each of them receives a luminous flux shifted in spatial phase by n / 2 relative to the previous photodetector, and turned on in pairs through one

according to the balanced circuit, two amplifiers 14 and 15 photocurrents and two inverters 16 and 17, the inputs of which are connected to the outputs of the amplifiers

14 and 15 photocurrents. Amplifier outputs 14 and

The 15 photocurrents and outputs of the inverters 16 and 17 are outputs of the raster converter 1.

The functional diagram of a possible implementation of block 2 determining the quadrant of signals (Fig. 1) contains four

comparator 18-21 and four logical elements 22-25 And, each of which has two inputs. The inputs of the quadrant signal determination unit 2 are interconnected:

measuring and reference inputs of comparators 18 and 21;

reference inputs of the comparators 18 and 19; measuring and reference inputs of comparators 19 and 20;

measuring inputs of comparators 20 and 21.

Comparators 18-21 are connected to the inputs of logic elements 22-25 And as follows:

the output of the comparator 18 is connected to the first inputs of the elements 22 and 25 And;

the output of the comparator 19 is connected to the first input of the And element 23 and the second input of the And element 22;

the output of the comparator 20 is connected to the second inputs of the elements 23 and 24 And;

the output of the comparator 21 is connected to the first input of the element And And the second input of the element 25 Vl,

Outputs of logic elements 22-25 AND

are outputs of the quadrant signal determination unit 2.

A possible implementation of the block 6 phase switch (figure 1) contains

two inverters 26 and 27, the inputs of which are the inputs of the block 6 of the phase switch, the first differentiating element 28, the input of which is connected to the input of the inverter 26, the second differentiating element 29,

the input of which is connected to the output of the inverter 26, and two logic elements 30, 31 2I-2I-OR. The inputs of the first circuit 2I of the element 30 are connected to the outputs of the differentiating element 28 and the inverter 27, and the inputs of the second circuit 2I are connected to the output of the differentiating element 29 and the input of the inverter 27. The inputs of the first circuit 2I of the second element 31 are connected to the input of the inverter 27 and the output of the differentiating element 28, and the inputs of the second circuit 2I are connected to the outputs of the inverter 27 and the differentiating element 29. The outputs of the phase switch unit 6 are the outputs of the 2I-2I-OR elements 30 and 31.

A possible implementation of the discrete switch 7 (Fig. 1) contains two elements 32 and 33 OR with two inputs each, the inputs of which are the control inputs of the discrete switch 7, and two logic elements 34 and 35 2I-2 AND-OR. The first inputs of the first circuits 2I elements 34 and 35 are connected to the output of the logical element 32 OR, and the first inputs of the second circuits 2I elements 34 and 35 are connected to the output of the logical element 33 OR. The second input of the first circuit 2I of the element 34 and the second input of the second circuit 2I of the element 35 are interconnected and are the first information input of the discrete switch 7, the second information input of which is formed by being connected to each other by the second input of the second circuit 2I of the element 34 and the second input of the first circuit 2I item 35.

The device operates as follows.

When the measuring raster of the modulator 9 is moved, the photocurrent in the photodetectors 10-13 periodically changes due to the modulation of the light flux by the conjugation of the measuring and indicator rasters, and each photodetector 10-13 receives a light flux shifted by the spatial phase by / 2 relative to the previous photodetector. Taking into account that the photodetectors 10, 12 and 11, 13 are connected in a balanced circuit, two quadrature measuring signals without a constant component are fed to the inputs of the amplifiers 14 and 15 of the photocurrents. When the measuring raster is moved in one direction, the change in the signal at the input of the photocurrent amplifier 14 lags in phase by a quarter of the period from the change in the second quadrature signal generated by the pair of photodetectors 11 and 13, and when the measuring raster is moved in the opposite direction, the second quadrature signal lags the first by the same quarter of the period. Therefore, the sign of the phase shift between the quadrature signals characterizes the direction of the measured movement. The main quadrature signals and their inversions, obtained at the output 5 by the inverter 16 and 17, are converted by comparators 18-21 of the unit 2 for determining the quadrant of signals into rectangular pulses, while the pulse repetition period corresponds to the displacement

0 measurement raster one step. The rectangular pulses generated by the comparators 18-21 are supplied to the logic elements 22-25 AND, at the output of which the output signals of the signal quadrant determination unit 2 are generated. With the same amplitudes of the measuring signals of the raster converter 1, the duration of each output signal of the block 2 of determining the quadrant of signals

0 is equal to a quarter of the period of the measuring signal, while the pulse at the output of element 22 And is present when the phase of the main sinusoidal signal of the raster transducer 1 changes within

5 -45 - + 45 °. at the output of element 23 AND - in

limits 45-135 °, at the output of the element 24 AND

- within 135-225 ° and at the outlet of the element

25 And - in the range of 225-315 °, respectively.

The control signals generated by block 2 of the signal quadrant are fed to the control inputs of the analog switch 3, to the corresponding information inputs of which the measuring signals of the raster converter 1 are fed. At the output of the analog switch 3, a linear-triangular signal is formed, which represents linear sections of the signals of the raster converter 1, in this case.

0 the length of the sections corresponds to a quarter of the period of the measuring signals, and the midpoints of the sections coincide with the zero values of the measuring signals. Timing diagrams illustrating the operation of the unit 2 for determining the quadrant of signals and analog switch 3. are shown in Fig. 2. The generated periodic linear-triangular signal has a double frequency in comparison

0 with the frequency of the signals of the raster converter 1, and its phase coincides with the phase of the main sinusoidal signal of the raster converter 1.

The generated linear triangular signal is fed to the input of the ADC 4. As a result of the conversion, the current value of the input signal is reproduced at the output of the ADC 4 as a number represented by a parallel binary code, with the low-frequency switching frequency

ADC 4 is proportional to the rate of change of the linear-triangular signal.

Reverse counting of pulses corresponding to the frequency of the least significant state change is performed by the pulse counting unit 8 taking into account the nature of the change (increase or decrease) of the linear-triangular signal at the ADC input 4 and the quadrant number of the measuring signals of the raster converter 1.

The sign of the increment of the linear-triangular signal is determined by forming a reference signal whose phase remains constant when the phase of the linear-triangular signal changes. In order to obtain a reference signal, the input of the EXCLUSIVE OR element 5 inverts signals from the two least significant bits of the ADC 4, and a reference signal is generated at its output, shifted by a quarter of the period of the relative signal from the second least significant bit of the ADC 4.

The generated reference signal and the signal from the second least significant bit of the ADC 4 are supplied to the inputs of the phase switch. These signals and their inversions, obtained at the output of inverters 26 and 27, form four rectangular voltages, phase shifted in phase relative to each other by a quarter of the period. The signal from the output of the second least significant bit of the ADC 4 and its inverse are supplied to the input of the differentiating elements 28 and 29, respectively. Differentiated pulses from the output of the elements 28 and 29 are fed to the corresponding inputs of the circuits 2I elements 30 and 31 2I-2I-OR. The reference signal and its inverse are supplied to the second inputs of circuits 2I of elements 30 and 31. For the switching circuit of the inputs of circuits 2I of the elements 30 and 31 shown in Fig. 1, counting pulses, the repetition period of which is equal to the switching period of the least significant bit of the ADC 4, are generated at the output of the element 30 with an increase in the linear-triangular voltage at the input of the ADC 4. If this decreases Voltage counting pulses appear at the output of element 31. Thus, when the measuring raster of the modulator 9 moves in one direction, the outputs of the logic elements 30 and 31 alternately generate counting pulses present on each of moves during the time the measuring raster moves by a quarter of the raster pitch. When the direction of movement changes, the phase of the linear-triangular signal changes by 180 °, and the sequence of occurrence of the counting pulses at the outputs of the elements 30 and 31 is reversed.

In order to supply counting pulses to the corresponding input of the pulse counting unit 8 when the measuring raster moves in one direction, the outputs of the phase switch are connected to a discrete switch 7, which simultaneously synchronizes with changing the sign of the rate of change of the linear-triangular voltage to the outputs of the phase switch to

0 input block 8 counting pulses. The operation of the discrete switch 7 is controlled by the signal quadrant determination unit 2. The signals corresponding to the odd and even numbers of quadrants of the signals are respectively supplied to the inputs of the circuits 32 and 33 of the AND AND of the discrete switch 7, the output signals from which are fed to the corresponding inputs of the circuits 2I of the logic elements 34 and 35 2I-2I-OR.

0 Counting pulses from the outputs of the phase switch are supplied to the corresponding second inputs of circuits 2I of elements 34 and 35. For the switching of inputs of circuits 2I of elements 34 and 35 shown in Fig. 1, counting pulses 5 appear at the output of logic element 34 and are supplied to the input + block 8 of the pulse counting if the measurement raster of the modulator 9 is moving in the forward direction. When moving in the opposite direction, counting pulses appear at the output of the logic element 35 and are fed to the input of the pulse counting unit 8.

Timing diagrams illustrating

5, the operation of the elements of the device that form the counting pulses and provide their reverse count by the pulse counting unit 8 is shown in FIG.

When the measuring probe is moved one step to the pulse counting unit 8, 4 n counting pulses are received (where n is the number of quanta equal to the mass of the least significant bit of the ADC corresponding to the range of the linear-triangular signal).

5 Thus, the proposed device has a resolution equal to 1/4 p step of the raster.

The proposed technical solution allows creating a displacement meter with high accuracy of measurement with a relatively simple technical implementation, as well as using rasters of a modulator with a large pitch (up to 100 μm or more) and providing a simple selection of parameters

5 mates to provide linear waveforms of the measurement signals.

The proposed technical implementation makes it possible to create a unified series of devices for measuring displacement with different interpolation coefficients on one basic sample by switching the outputs of the ADC.

In addition, due to its high resolution, the proposed device can be used as a converter in a digital tachogenerator.

Claims (1)

SUMMARY OF THE INVENTION A device for measuring the movement of an object, comprising a raster converter with four outputs, a quadrant for determining signals, four inputs of which are connected to the outputs of the raster converter, an analog switch, information and control inputs of which are connected respectively to the outputs of the raster converter and block determination of the quadrant of signals, a pulse counting unit, distinguishing- so that in order to increase the accuracy of measurement at low speeds, the object is equipped with an analog-to-digital converter, the input of which is connected to the output of the analog switch, an EXCLUSIVE OR element with an inversion, the inputs of which are connected to the two low-order bits of the analog-to-digital converter , a phase switch unit, the inputs of which are connected to the second low-order bit of the analog-to-digital converter and the output of the EXCLUSIVE OR element with inversion, a discrete switch, two information and even When the control inputs of which are connected respectively to the outputs of the phase switch unit and the outputs of the signal quadrant detection unit, the outputs of the discrete switch are connected to two inputs of the pulse counter. The signal at the input of the element fB K / X1x / gn J l Signal on the dhode element 21 Signal on bshod element 22 Signal on top of element 23 Signal on H / Had | element 24 Signal on bshod elem / 025 Signal Hff Dshode element .K l, F V V T V V V f F-cgsv v v ffi sinv V Qkiit  Schp jlj 1st bit ,, n kbadront pY + 1 x8adran / reverse   | / TO  R | / TO