SU1758429A1 - Displacement measuring device - Google Patents

Abstract

The invention relates to a measurement technique and is intended for ultrasonic measurement of linear movements of an object. The aim of the invention is to increase the noise immunity of the conversion by increasing the amplitude of the probing ultrasonic wave in the magnetostrictive acoustic conductor medium. This is achieved due to the excitation in the environment of the sound guide of the primary transducer of movements of a stack of M waves, the amplitude of each of which is the sum of the previous waves, which are simultaneously read at the M-points of the readout and summed. In this case, the dependence Ux), depending on the method of excitation and reading, is either monotonously increasing or exponentially increasing. The device for measuring displacements contains a rectilinear magnetostrictive duct 1 with acoustic dampers 2, a readout unit 3, a shake excitation unit 4, a recording amplifier 6, a read pulse shaper 7, a generator of 8 dual pulses, a poll counter 9, a code analyzer 10, D- trigger 11. measurement generator 12, result counter 13, input and output buses 14, 15 and 16, 17. The device is intended for use in robotic systems and complexes. 4 hp f-ly, 8 ill. yo

Description

 15 swaps

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1

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The invention relates to a measurement technique, namely, ultrasonic transducers of displacements, and can be used in robotic systems and complexes for measuring and controlling parameters of the kinematic motion of an object.

A device for measuring displacements is known, comprising a magnetostrictive duct, an acoustic damper, a tensile stabilizer, recording and reading elements with bias magnets, a read preamplifier, a single vibrator, a measuring oscillator, a trigger, an AGC block, a read amplifier, a switch, four buffer registers, a calculator and a comparator.

There is another device for measuring displacements, selected as a prototype, which contains a magnetostriction sound duct installed in acoustic dampers, trigger circuits, an IL element And a standby pulse generator, a recording pulse shaper, a moving recording coil, a fixed read coil, a read amplifier, a shaper pulses, counter, time converter, interval to code, conversion scale control unit, normalizer, sample frequency generator, AND element, counter restart, decoder.

A common drawback of the known devices is the lack of immunity due to the excitation of a single amplitude elastic wave in the magnetostrictive acoustic duct.

The purpose of the invention is to increase interference resistance, by increasing the amplitude of oscillation of the sound duct.

Fig. 1 is a highlight diagram of a device for measuring displacements; in fig. 2-4 are block diagrams of a device for measuring displacements with various implementation of the kinematic scheme of its primary displacement transducer; in fig. 5, b - execution of the main blocks 7, 8 of the device; in fig. 7 shows the waveform for recording and reading the primary displacement transducer for various methods of exciting ultrasonic waves; FIG. 8 is a graph of the function Ux p (M).

The device for measuring the displacement; eu (Fig. 1) contains a rectilinear magnetostrictive acoustic duct 1 fixed in acoustic dampers 2, a unit 3 for reading from M stationary concentrated reading elements with a bias magnet fixed on the acoustic duct near one acoustic damper, shaper 4 oscillation excitations with a bias magnet fixed to the suction duct with the possibility of movement between the limit stops 5 of the displacements and kinematically connected to the object of the displacement connected to the output y write silicon 6, read pulse shaper 7, 8 dual pulses generator, K-discharge d counter polling counter 9, 10 code logic analyzer, D-flip-flop 11, measurement generator 12, result counter 13, control spike 14, launch bus 15,

bus 16 request, p-tires 17 result. The outputs of the result counter 13 are connected to the result buses 17, and the counting input through the measurement generator 12 is connected to the forward output of the D flip-flop 11. Its inverse output is connected to the query bus 16, the synchronous input is connected to the outputs of the readout unit 3 via the read pulse generator 7, single the input is connected to the zero inputs of counters 9, 13 and connected to the start bus 15, and the zero input is connected to the control bus 14 and connected to one input of the code analyzer 10, its other K inputs are connected to the outputs of the polling counter 9, and the output is connected 8 input-pulse generator. One of its output is connected to the counting input of the polling counter 9, the other is connected to the input of the recording amplifier 6.

In addition, in the device for measuring

displacement (Fig. 2), a pulse generator 18 is connected to the counting input of the polling counter 9 and the input of the recording amplifier 6. Moreover, the reading unit 3 is made movable with the possibility of moving

along the guide tube 1 between the limiters 5 displacements and connected to the object to be moved, and the driver 4 of oscillation excitation is fixed and fixed on the guide tube 1 on the reference

distance (about from its free end.

In addition, an additional oscillator 19 from (M -1) lumped elements is introduced into the device for measuring displacements (Fig. 3).

recordings with a bias magnet fixed on the suction line 1 at a reference distance from the main excitation oscillator 4 with the possibility of movement between the limiters 5 displacements. Their outputs are connected to the outputs of the recording amplifier 6.

In addition, the distributed excitation winding 20 is fixed in the device for measuring displacements (FIG. 4)

fixed in the working section of the guide duct 1 between the limiters 5 displacements, and a block 21 of M bias magnets fixed on the core of the tube with the possibility of displacement along the excitation winding 20 and kinematically connected to the object of displacements. The terminals of the excitation winding 20 are connected to the outputs of the recording amplifier b.

The device works as follows.

Initially, the device (FIG. Is in the locked state. A digital signal is set up via its control bus 14 Stop, blocking the inputs of the code analyzer 10 and holding the D-flip-flop 11 in the zero state, forming a digital signal on the request bus 16. When cleared Signal halts The device is placed on standby for the start of a conversion cycle.

In response to the Zarbs signal, the user sends a digital signal on the startup bus 15, which triggers the polling and result counters 9, 13 and the 0-flip-flop 11 to the one state. Switching the D-flip-flop 11 indicates the beginning of the cycle converting the desired linear movement of an object to a digital code Nx. On its signal, a digital measuring generator 12 is triggered, generating a series of pulses of the frequency fo, counted by the result counter 13.

Setting the polling counter 9 to zero causes a static signal to be generated at the output of the analyzer 10, which allows the generator to start 8 dual pulses. Generator 8 generates rectangular video pulses with a frequency of ton Unp / li, where Unp is the phase velocity of the ultrasonic (US) wave in the acoustic duct; And, the distance between the M readout elements of the readout unit 3, which is fed to the counting input of the interrogation counter 9 and counted. The number of pulses must not exceed the number M of the read elements used in the read block 3. Upon reaching this value NI 2c M, a signal is generated at the output of the logic analyzer 10 of the code that blocks the operation of the generator of 8 dual pulses until the next conversion cycle.

At another output of the generator 8, dual rectangular video pulses of duration d and with a duty cycle of 0-2 are generated in each of the M clock, (Fig. 76). They are passed to the signal input of the recording amplifier 6 and are converted into current parcels exciting shaper A due to oscillations that are at the time of the survey at the desired distance 1X from the reading unit 3. As a result of the magnetomechanical transformation, under the shape of the injector 4 in the acoustic duct 1, a series of M ultrasonic waves of double amplitude (Fig. 76) is excited due to the superpositional composition of the adjacent single half-waves (Fig. 7a). They pass through the sound pipe 1 to

0 to the readout unit 3 for the required travel time Tx Ix / Unp and the analog signals of double amplitude readout on the leads M of the concentrated read elements

5 + Ј x

Ui.i ki.2Uo.e r, (1)

where k 0,8-0.9 - coefficient of proportionality;

Uo is the unit amplitude of the read signal;

ft is the attenuation coefficient of the ultrasonic wave in the medium of the sound duct.

The inputs to the driver of the read pulse 7, the induced signals 5 (1) are summed and form a single-pulse read signal of increased amplitude

Ux 2 Ui.r; (2)

0, which is converted to a rectangular video read pulse and switches the D-flip-flop 11 to the initial state. The operation of the measuring generator 12 is completed, and on the n outputs of the counter 13, the result

5 shows the search 1x move code

NX Tx.fo

V

np

fo

)

arriving at result tires 17, will generate a signal of a movement code. By bus

16, the request is set to a request signal and the device is put into standby mode. Then the whole conversion process is carried out without change.

Used in the device, a read pulse shaper 7 is made (Fig. 6) on negative and positive half diode valves 22 and 24, diode limiters 23 and 25, resistor 26, forming element 27 (Schmitt trigger). Diodes 22 shunt the negative half-waves of the readout signals onto the common bus, which block the diodes 23. That leads to the formation in the circuit of the elements 25. 26 the total readout signal (2) for

start forming element 27.

The dual-use generator 8 is made according to the scheme of cascade connection of two controlled generators (Fig. 6). The first digital low-frequency generator

made on the logical element AND-NOT 28, NPN-transistor32 conductor, resistors 33-35 and capacitor 37, generates signals with frequency f0n - / Top Unp / h. From his signals, a second digital high-frequency oscillator is triggered on the NAND logic gates 29-31, resistor 36 and capacitor 38. It generates signals of a higher frequency equal to fi 1/2 hp. Moreover, the pulse duration of the signal of the first generator is equal to Ti (3 ... 4) Hn. That allows generating, by the second output of the generator 8, dual pulses according to FIG. 76.

Consequently, the application of the dual pulse method using a block of 3 readings from M readout elements makes it possible to form an analogue readout signal (2), described by a linear dependence of the form Ux / (M) (direct 1 in Fig. 8), and increase in Ux / Uo times the signal-to-noise ratio compared to the prototype.

The kinematic scheme of the primary converter of the “movements of the device of FIG. 1 can be somewhat simplified if its sound pipe 1 is turned on in a pseudo-closed circuit, the excitation generator 4 is fixed at the reference distance 1 ° from the free end of the sound guide, and the reading unit 3 with M lumped reading elements is, on the contrary, movable and connected to the displaced object (Fig 2). Such an embodiment of the kinematic scheme of the primary displacement transducer allows using in the secondary transducer a digital pulse generator 18 of a simpler structure, for example, according to the digital transmitter circuit of the generator 8 dual pulses.

The pulse generator 18 generates a series of (M + 1) rectangular video pulses of the frequency fon, which are counted by the poll counter 9. Installing the former 4 at a distance lo H / 2 from the free end of the suction duct 1 makes it possible to form in its medium probing ultrasonic waves of double amplitude (1), similar to FIG. 76 due to the superpositional addition of a direct and reflected half-wave. Only the very first amplitude in a pack of (M + 1) pulses has a single amplitude.

The packet from (M + 1) of the ultrasonic waves excited in the sound pipe 1 passes into the zone of magneto-elastic conversion through the time Tx being sought and is read by the reading unit 3, generating an analog signal of the increased amplitude (2). Further, the whole

The signal conversion process in the device of FIG. 1 does not differ from that considered. As a result, an increase of 2M in the signal-to-interference ratio of the device relative to the prototype is achieved (right 1 of Fig. 8).

The effectiveness of the device in FIG. 1, 2 can be increased if the kinematic scheme of the primary displacement transducer includes an additional oscillator 19, which, together with the main driver 4, contains M lumped recording elements with a bias magnet,

5 are installed on the core pipe 1 on the reference distance h one relative to the other and connected in parallel in parallel with the polarity of the leads (not shown in Fig. 3).

0 In this case, the generator 18 pulses generates a series of M rectangular video pulses of recording duration hn. which, when converted to current parcels by amplifier 6 records, excite in the medium

5 chimney 1 sounding ultrasonic waves. With each successive cycle, their amplitude increases by the magnitude of the single wave (Fig. 7a) due to the superpositional combination of half waves in the magnetomechanical transformation zones, as shown in Fig. 7c.

Excited package of ultrasonic waves (Fig. 7c)

increased amplitude spreads

in the direction of the block 3 readout and through time

Tx reaches it, reads, generates a resultant signal m - 1

 + X UM (4)

i 1

Further, the whole process of signal conversion is performed without modification, as described above. With this method of exciting ultrasonic sounding waves, the magnitude of the output voltage (4) can reach significant values when the choice of the number M of recording and reading elements in blocks 4, 19 and 3 is appropriate. This increases the noise immunity of the device relative to the prototype (curve 2 of FIG. eight).

0 In addition, the kinematic scheme of the primary displacement transducer of FIG. 3 can be performed by non-contact circuit, as shown in FIG. 4. In this case, along the entire length of the working part of the sound duct

5 1, the fixed distributed excitation winding 20 is fixed, connected to the terminals of the recording amplifier b. Along the winding 20, a block 21 of M of the same type bias magnets mounted on the reference distance H is moved.

relative to the other and moving between the limiters 5 movements.

When current pulse parcels are supplied to the excitation winding M from record amplifier 6, magnetic sections of magnetic conductor 1 magnetized in sections of the acoustic duct 1, amplitude transformed ultrasonic sounding waves are excited (Fig. 7c). After the required time of moving Tx, the package of ultrasonic waves is read by block 3 of reading with the formation of the resultant signal of reading (4). Further, the whole process of signal conversion is performed according to what has been considered. As a result, a significant increase in the noise immunity of the device relative to the prototype is achieved, which confirms curve 2 of the functional dependence Ux – UHM) of FIG. eight.

The use of acoustic dampers 2 in the kinematic scheme of the device’s primary transducer eliminates the generation of ultrasound waves от reflections on the medium of the magnetostrictive conductor and their accumulation, thus ensuring the implementation of the described algorithm of the device operation.

Thus, the proposed approaches for the excitation and reading of ultrasonic waves extend to all types of normal elastic waves (longitudinal, torsional) excited in the magnetostrictive medium of the wavelength path of the converter, and can significantly increase the noise immunity of the conversion relative to the prototype without significant complication of the structure.

Claims (4)

1. A device for measuring displacements containing a magnetostriction acoustic conductor, the ends of which are damped, an excitation oscillator in the acoustic conductor with a bias magnet and a readout unit containing one readout element mounted on the acoustic conduit with the possibility of their mutual displacement, a recording amplifier whose output is connected with the drive driver input, the polling counter connected in series and the measuring generator, the output of which is connected to the input of the result counter characterized in that. what. In order to increase noise immunity by increasing the amplitude of oscillations in the duct, it is equipped with at least one additional element of reading, a read driver, whose input is connected to the reader, and whose output is connected in series with D-trigger. a measuring generator and a result counter, a dual pulse generator, one output of which is connected to the input of an excitation oscillator, another output is connected to a polling counter connected to a logic stroke analyzer, the output of which is connected to the input of a dual pulse generator. 2. The device according to claim 1, characterized in that the generator of double pulses is used as a pulse generator, and the oscillator driver is mounted stationary on the conductor, 3. Device pop. C. distinguishing - in that it is additionally equipped not  With less than one type of vibration excitation element installed in the excitation generator on the acoustic duct at a given distance from each other, a double pulse generator is used as the pulse generator, and the blocking reading is fixed on the acoustic duct. 4. Device pop. 1, that is, with the exciter driver made in the form of a distributed winding fixedly mounted on the sound duct and several displacement magnets of the same type mounted at predetermined distances from each other . % 6Zfr89a THEM mr 91 wi s epf ezwsii FIG. B / i0 GO 501 b 30 gon u-10 and