SU1104466A1 - Position control device - Google Patents

Abstract

A POSITIONAL CONTROL DEVICE, containing a computing unit associated with six buffer highlights, a comparison unit connected to the second output of the first buffer unit, and a sequentially connected control signal generator, matching converter, actuator and sensor, characterized in that increase the accuracy of the device, it contains four amplifiers, an adder, a threshold unit, and a displacement signal generator, the first input of which is connected to the output of the comparison unit, second the input of the first buffer block and through the threshold block with the input of the comparison block, the second input with the second output of the second buffer block, and the output with the first input i of the control signal generator, the second outputs of the third, fourth, (L fifth and sixth buffer blocks are connected with the first inputs of the first, second, third and fourth amplifiers, respectively, the outputs of which through the adder are connected to the second inputs of the driver and the threshold unit, the second inputs of the first and second amplifiers are connected to ne vym rely sensor output; 1 and, the second input. connected to the second inputs of the third and fourth amplifiers ,. 4 a: a:

Description

This invention relates to automation and. . computer technology and can be used to control precision technological equipment with numerical control.  The following drive is known, consisting of a code input device, an adder, a voltage converter, a driver, a speed master, a power amplifier, a motor, a mechanism, a speed sensor, a position sensor, a phase converter - code ij -.  The disadvantages of this servo drive include its low accuracy and positional resolution, caused by the presence of a phase conversion error in the code and the finiteness of the minimum phase quantization step, as well as its complexity, especially with a significant difference between.  is the required resolution of position and accuracy of mining.  It is also known that a positioning control device consisting of a position adjuster, a digital detector, a subtractive circuit, a digital-analog converter, a servo amplifier, a servo valve, an actuator 23.  The disadvantages of such a device are low accuracy and resolution of positioning, limited by the minimum level of quantization of the signal, which characterizes the movement.  The closest to the proposed technical entity is a process control system comprising a driver, a comparator, a driver for control signals, a matching converter, an actuator, an object of regulation, a sensor for the adjustable parameter, a converter for analogue – code, switch 3.  The disadvantages of the known system are low resolution and positioning accuracy limited to the minimum level. quantizing the signal characterizing the movement.  The aim of the invention is to improve the accuracy and resolution of positioning by keeping the liver at a constant maximum and independent of the discreteness of positioning the steepness of the control signal at the retention point.  This goal is achieved by the fact that a device for positional control, containing a computing unit associated with six buffer blocks, a comparison unit connected to the second output of the first buffer block, and a serially connected control signal generator, matching converter, actuator and position sensor, additionally contains four amplifiers, an adder -, a threshold.  the second block and the shaper signal generator, the first input of which is connected to the output of the comparison unit, the second input of the first buffer block and through the threshold unit to the input of the comparison unit, the second input to the second output of the second buffer block, and the output to the first input of the control signaling device, the second the outputs of the third, fourth, fifth, and sixth buffer blocks are connected to the first inputs of the first, second, third, and fourth amplifiers, the outputs of which through the adder are connected to the second inputs of the driver signal and a threshold unit perogo and second inputs of the second amplifiers are connected to the first output of the position sensor, a second input connected to the second inputs of the third and fourth amplifiers.  FIG.  1 shows a block diagram of the device; in fig.  2 -. diagrams explaining his work; in fig.  3 - Schema amplifier with adjustable transmission coefficient; in fig.  4 - the same. adder; in fig. 5the same, the displacement signal generator; in fig.  6 — control signal generator; in fig.  -7 scheme of buffer blocks; in fig.  8the same threshold block; in fig. The same, comparison unit.  The device consists of amplifiers 1-4 with adjustable transmission ratio, adder 5, control signal generator 6, movement signal signal generator 7, matching converter 8, threshold unit 9, actuator 10, position sensor 11, comparison unit 12, computing unit 13, buffer blocks 14 -nineteen.   The inputs of amplifiers 1 and 2 are interconnected and connected to one of the inputs of the sensor 11 position, the inputs of amplifiers 3 and 4 are also interconnected and connected to the second output of the sensor 11 position.  The outputs of the amplifiers are connected to the inputs of the adder 5, the output of which is connected to one of the inputs of the driver 6 of the control signals and the input of the threshold unit 9.  The second input of the driver of the control signals is connected to the output of the driver of the travel signals 7.  The output of the driver 6 is connected to the input of a matching converter 8, the output of which is connected to the executive body 10, which is rigidly connected to the position sensor 11.  The output of the threshold unit 9 is connected to the counting input of the comparison unit 12, the output of which is associated with the inhibitor inputs of the imaging unit 7, the threshold unit 9 and the buffer unit 19 output. The output of the buffer unit 19 is connected to the installation inputs of the comparison unit 12, and the output of the buffer unit 18 is connected to the installation shaper inputs 7.  The installation inputs of the amplifiers 1-4 are connected to the outputs of the buffer blocks 17,16,15, and 14, respectively.  Channel inputs of the buffer blocks 14 - 19 are connected to the channel of the computing unit 13.  The device works as follows.  First, the number N, t is determined from the coordinate of the positioning point previously stored in the memory of the computing unit 13. e.  the number of integer periods of the Asinx signal of the position sensor (when the actuator 10 is moved, the position sensor 11 generates the signals AbchpH and | Aso5) taken as scale and placed between the given point X; and the XQ point, taken as the origin, and also the part of the period S by the formula Xi-Xg m-MASj -f is an integer number of masses U Headquarters; ° i- o-E-j t-part of the scale; "-Scale is the distance corresponding to the period of the signal of the sensor 11 position.  The value of the phase change of the signals of the sensor 11 is then determined.  when the executive body 10 is moved by 5 xp (f4-2, - „.  After that, the phase shift of the signal of the sensor 11 of the position chosen for the reference, for example, by the value of c, is carried out so that at the positioning point X the value of the phase of the reference signal A-SinX is 2in.  To effect a phase shift, the AsinX signal of position sensor 11 is applied to the inputs of amplifiers 1 and 2, and the Acogx signal -. to the inputs of amplifiers 3 and 4, with amplifiers 2 and 4 being inverting, and amplifiers 1 and 3 being non-inverting.  Thus, at the outputs of the amplifiers, we have the signals k, AeinX) -k2Asin X, k AcosX, -k4 °, which are fed to the inputs of the adder 5.  The transmission coefficients: and amplifiers K, - K4 are chosen so that the total signal from the output of the adder 5 has the form A9in (x + s), where cf is the specified phase shift.  To determine the relationship between the phase shift of the sum signal and the amplitudes K, A, -K2A, -KzA ,.  . .  , we add the signals at the input of the adder 5 in the following form: k, AsinX-l A5inX Alk, -ka) 5; nX-, k - ,, Асо9Х-1 4 fccosx fttVy or А of  1 V, Alk, -kj StnX -Alkj-k4icosX.  According to the well-known f43 expression, after summing the received signals we have Alk, -l 2binX4A (k: j-k4lcosX B BsinU -t y, where, Bni (uv k Mv74F.  NW) The connection between the given phase shift and.  the values of the gains of the amplifiers 1-4 are determined from expressions (2) and (3), setting and marking. . fi.  tgq fi / oi. -, (i Solve the resulting system by the equation of L and / J:.  remove K-icosqt, ft- ± siotf t,.  From the diagrams explaining the operation of the device, it can be seen that the magnitude of the new shift can be found within O - 2n k, the investigator k, -k coS4 k5-4 -5incp, Ic -kji-coscf7 c-C -. ps g-, k. k ,. -coSC;,.  ky-k4 Ic -kjrCOSO-1 k, -k ,. 6, ncf. The absolute values of the coefficients of the amplifiers K,, ((4 are chosen arbitrarily from 0 to the maximum value.  After assigning the calculated transmission coefficients of amplifiers 1-4 by submitting the corresponding codes from computing unit 13 through buffer blocks 14 to 17 to the installation inputs of amplifiers 1 to 4, the number 12 +1 or N (npHtp 0) is rewritten through buffer block 19 through the comparison block of computing unit 13 .  Making these settings, the computing unit 13, through the buffer unit 18, sets the code of the force required to move the actuator 10 to the installation input of the displacement signal generator 7, from which output the pulse form voltage through the control signal generator 6, the matching converter 8 feeds drive executive body 10.  Moreover, the first half of the way, the executive body 10 moves to acceleration, and the second - slowly, so that at the positioning point the speed of movement of the executive body 10 is or approaches zero.  Braking is carried out by changing the polarity of the voltage supplying the drive on command from the computing unit 13.  At the entrance of the ban shaper 7 there is a resolving potential.  The harmonic signal A intx-KflnpH arising at the output of the adder 5 displaces the actuator 10 through the threshold unit 9 operating at the zero threshold, arrives in the form of short pulses of the same frequency to the counting input of the comparator unit 12.  At the entrance of the prohibition of the threshold unit 9 is also worth permitting potential.  At the moment when the numbers are equal, the comparison unit calculates 12 pulses to the number previously set in it (N + 1 or N /), which corresponds to the moment when the actuator leaves the positioning point 10, and an output pulse is generated at the output of the comparison unit 12, which prohibits the operation of the signal conditioner 7 the transfer unit and the threshold unit 9, and through the buffer unit 19 enters the computational unit 13 as a command for switching the positioning device from the mode of moving the executive body 10 to the mode of holding it at the controlled point The drive of the actuator 10 in the hold mode is carried out on the harmonic signal from the output of the adder 5 through another input of the driver 6 of the control signals and the matching converter 8.  When the actuator 10 is transferred to the next positioning point Xa, the indicated actions are repeated, but the signal A9inx, which characterizes the movement, is shifted by the value tfj-q fo where Cf2 is the phase shift of the signal determined from the amount of movement in the second cycle; Cf, is the phase shift of the signal in the first cycle.  The device works as follows.  Adjustable gain amplifiers (FIG.  3) made on the basis of operational amplifiers K140UD8, two registers K155IR1, eight inverters, with an open collection TopciM K155ЛН2 and a matrix of weight resistances.  The gain control is performed in the pen cascade.  The transmission coefficient of such an amplifier has the form (| € ,, where Eg; is the total conductivity of the matrix of weighting resistances; w-conductivity of the feedback circuit.  By changing the total conductivity of the matrix by submitting the appropriate code to the installation inputs of the registers, we set the required gain coefficient of the amplifier.  The second amplifier stage is an inverter with a gain of one.  Adder (FIG.  4) also performed on the K140UD8 operational amplifier.  The summed signals through the resistance R arrive at the inverting input of the amplifier.  Motion signal generator (FIG.  5) contains a readout counter (chip K155IE7), three D -trigger (chip K155TM2, two logical circuits AND (chip K155LI1), an operational amplifier (chip K140UD8.  Impulses. From a 1 MHz crystal oscillator, they go to the subtracting input of the counter, to the installation inputs of which, from the computing unit, a fourteen-digit code is sent through the buffer unit, which determines the width of the acceleration or deceleration pulse of the actuator.  HaD is the inputs of the trigger T, the code of the fourteenth bit arrives, and the trigger Tg is the fifteenth bit of the same number.  On the Output from the Buffer Device command, the set codes are overwritten into the counter and the triggers T and Tg. As a result, a positive voltage drop (e.g., an acceleration output) appears at the output of one of the logic cells.  After the counter is reset by the geerator pulses, the overflow pulse from its output through the trigger Td removes the resolution from the inputs of the logic cells and a negative voltage drop is generated at the acceleration output.  1In this way, during the time the counter is zeroed, a positive pulse acts at the output of one of the logic cells, during which the actuator is accelerated or slowed down.  The outputs of the logic cells are connected to the inverting and non-inverting inputs of the operational amplifier, respectively.  Consequently, at the output of the amplifier, polarized acceleration or deceleration pulses are formed.  Zener diodes allow the amplifier to be disconnected from the second input of the driver 6 of the control signals in the absence of acceleration or deceleration pulses.  At the moment when the actuator leaves the position of the prohibition signal from the comparison circuit, the state of the flip-flops T and Tj changes and the operation of the whole circuit is prohibited. The control signal former (Fig.  6) performed on the K140UD8 operational amplifier, the inverting input of which receives control signals from the displacement signal generator and from the adder.  In order to reduce the time of the transient process when practicing random disturbances in the positioning mode, the adder enters the input of the driver of control signals through the RC-chain.  The transfer ratio of the control signal generator, as well as the amplitudes of the signals at its input, are selected so as to ensure the linear operation of the amplifier for the adder signals and the deep saturation mode for the pulses of the displacement signal generator, t. e.  With the simultaneous action of the indicated signals, the amplifier does not exit saturation mode at any admissible levels of the adder signal.  The matching converter is a push-pull power amplifier with dual-pole power.  .  The type of circuit and its parameters are completely determined by its load, i. E.  driven executive body.  The position sensor is a laser interferometer with photodetectors FD-27K and preamplifiers on K574UD B microchips.  A mass-produced computer Electronics-60, selected on the basis of microprocessor М2, memory devices P2 (15У304003) and ПП2 (15УЗЛП2048-16), was chosen as a computing unit.  Buffer blocks are commercially available devices for parallel exchange of I1 (15KM-180-004) microcomputer microchannel with external devices and contain (Fig.  7 channel transceivers, address decoder, control signal decoder, data multiplexer, data register.  Threshold block (FIG. 8) contains a Schmitt trigger with a zero threshold, performed on the chip (K140UD8), a transistor switch, logic circuit (I1K155LAZ).  and one-shot (. K155AG1.  Comparison Chart (. FIG.  9 contains a subtractive counter (K155IE7) and trigger SK155TM21.  The proposed invention in comparison with the known, possessing the same quality factor of the control circuit, is more accurate.  In the proposed control system, the steepness of the control signal at the retention point is maximal and constant for any movements of the actuator, which allows for the highest possible transmission coefficient in the control circuit and, even with small control signals, to achieve high control accuracy.  The accuracy and resolution of the proposed position control device is improved primarily due to the highest possible accuracy of determining the phase of the control signal of the position of the actuator at the retention point, which makes a significant contribution to the system error sj.  Imagine the input control signal as the sum of the desired Sinti / signal and the noise signal g (. t, t. e. U8j 6iTiq t g (t). The system of holding the actuator in a predetermined position stabilizes the phase of the signal 51п С |) 4У (f, where У I-) the random change of the phase of the total signal, due to the effect of interference (11.  It is almost impossible to determine at the input of the containment system what caused the change in the input voltage: whether the actuator was displaced and, consequently, if If moved away from a given fixed value or the effect of photodetectors drift interference, light sources, low-noise noise of electronic circuit elements, etc. P.  Thus, the control signal can be represented as) + ai-5,) f (t sine, (t) 5in (() (t) C05t sin y (t) ((V + (t) C05tVSi tyWlP of the sintyUl positive) g) in the Taylor series, we get f ,. , f. “; Ii. . . . b ,. . . s4 ". . L, (o-f. . . . jco3 ,.  Nebrega members of the second order of smallness USH «0. raE, we get. . .  . . . .  yw-gttl / cozy  Analysis of the last expression shows that, by choosing, it is possible to reduce the magnitude of the phase noise to the input of the control system superimposed on the control signal.  As is known, 6j, the mean square error value is directly proportional to the noise spectral density, acting in the control system.  In the proposed device, the executive point holding points on the phase axis of the control signal always correspond to the minimum phase noise of the control signal C} a multiple of 27).  In the known device, other values may correspond to holding points.  For example, if the holding point corresponds to ((cos (, 17), then the phase fluctuations in the known control system are six times larger than the proposed one, T. K. YB is always a multiple of 2n (com2n-x1, where, 1, 2 ,. . .  Accordingly, the accuracy of the known control system is lower than that of the proposed one.  Taking into account that. the fact that the accuracy of the control system is also influenced by the internal noise of the system, which may differ to some extent for different implementations of the device and which is several times less than the noise at the input of the system, and given the calculations, the gain in accuracy and resolution ability to use the proposed device will be about 2-3 times.

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Claims (1)

A device for positional control, comprising a computing unit associated with six buffer units, a comparison unit connected to a second output of the first buffer unit, and serially connected a signal shaper 'control, a matching converter, an actuator, and a position sensor, characterized in that , in order to improve the accuracy of the device, it contains four amplifiers, an adder, a threshold block and a shaper of the displacement signal, the first input of which is connected to the output of the comparison unit, the second input ohm of the first buffer block and through the threshold block with the input of the comparison block, the second input with the second output of the second buffer block, and the output with the first input of the shaper control signal, g the second outputs of the third, fourth, fifth and sixth buffer blocks are connected to the first inputs, respectively the first, second, third and fourth amplifiers, the outputs of which are connected through the adder to the second inputs of the driver. control signal and the threshold unit, the second inputs of the first and second amplifiers are connected to the first output of the sensor ka position, the second entrance. connected to the second inputs of the third and fourth amplifiers.