SU1231489A1 - Device for determining parameters of second-order dynamic element - Google Patents

Abstract

The invention relates to control devices and can be used to determine the dynamic characteristics of instrumentation and automation devices, for example, the trace of all systems. The purpose of the invention is to increase the speed of determining the parameters of the transfer function of a dynamic link with an arbitrary input action. The device contains an input signal converter, the input of which is connected to the input of the object under study and the output of the switch, and an output signal converter whose input is connected through the normalizing unit to the output of the object under study, and the outputs to the inputs of two difference dividers, others. the inputs of which are connected to the outputs of the input signal converter, and the outputs of both differential dividers are connected to the inputs of two memory blocks, the third inputs of which are connected to the second output of the control unit, whose input is connected to the third inputs of the differential dividers and the output of the normalizing block, and the first and third rods - to the second and third inputs of the switch, the first input of which receives an arbitrary input signal. 8 Il. with $ (L

Description

The invention relates to control devices and can be used in devices and devices designed to identify elements and objects of automatic control systems, for example, the trace of iipix systems.

The purpose of the invention is to increase the speed of determining the parameters of the transfer function of a second-order object under investigation with an arbitrary input signal.

FIG. 1 shows a block diagram of the proposed device for determining the parameters of the second-order dynamic link in FIG. 2 - input and output signal converters; in fig. 3 - differential signal divider; 4, a control unit; FIG. 5 shows the memory blocks of FIG. 6 — delay block in FIG. 7 — time relay; in fig. 8 - division unit.

The block diagrams contain the object under study 1, the first switch 2, the normalizing unit 3, the input signal converter 4, the output signal converter 5, the first divider 6 of the differential signals., The second divider 7 of the differential signals, the control block 8, the memory block 9 for calculating the first coefficient , a memory unit 10 for calculating a second coefficient, DC amplifiers 11 and 12, a subtracting unit 13, a unit; 14 divisions, subtraction unit 15, test voltage source 16, second switch 17, signal delay unit 18, Reset button 19 with normally closed contacts, Count button 20 with normally open contacts, memory control block signal generating unit 21, blocking relay 22 memory control signal, latch 23, differentiator 24, subtraction unit 25, resistor 26, capacitor 27, DC amplifier 28,, memory block control relay 29, time relay 30, inverter 31, coincidence circuit 32, transistor 33, conden ator 34, resistor 35, multiplying unit 36, amplifiers 37 and 38, a DC circuit switch 40 comparator 39, an inverter 41, a block forming unit 42, diodes 43 and 44.

In the device for determining the parameters of the dynamic link of the second

As a test object 1, disassemblies of automatic control systems can be used, in which the re-function can be represented by the expression:

TO

 + a, p

+ 1

(one)

Such devices may, for example, include the following systems, closed-loop position feedback, amplifiers, and various filters. The device is most suitable for identifying objects whose parameters can vary during the experiment. In the study of trace - 1DH systems, a signal is used as the output signal, taken from the feedback sensor, for example, a potentiometer.

The normalizing unit 3 serves to determine the static gain K of the object under study 1 and to obtain the required output signal level and is a DC amplifier with variable transmission coefficients, which is achieved by changing its input resistance.

As the first switch 2, any contact and proximity switch can be used, for example a relay.

The converters of the input 4 and output 5 signals (Fig. 2) consist of two filters connected in parallel with identical constant time pairs, i.e. the time constant of the first filter (made on the DC amplifier 11) of the converter 4 of the input signal is equal to the time constant of the first filter of the converter 5 of the output signal.

The filter time constants are determined by the expression

and are chosen so that their cyniecTBe.HHo values differ, for example

50

(These T values are determined by the parameters of the input signal. In particular, with a sinusoidal input signal x (t), AsiniJt is constant

time of the first filter t. -.

  ij.

Changing the filter time constant is achieved by changing the resistance of the resistor R-.

The first 6 and second 7 dividers of the difference signals (FIG. 3) are identical in structure and consist of two blocks 13 and 15 of the subtraction and block 14 of the division, the first and second inputs of which are connected to the outputs of blocks 13 and 15 of the subtraction, respectively. The first input of the subtracting unit 13 is connected to the first input of the blocks 6 and 7 dividing the difference signals, the second input of which is connected to the second input

I give blocks 13 and 15 of the subtraction, and the first input of block 15 of the subtract is connected to the third input of blocks 6 and 7, the output of which is connected to the output of block 14 of the division.

Block 14 (FIG. 8) of dividing performs the operation of dividing two alternating stresses in 4 quadrants and maintains operability when the divider passes through zero. The dividing unit 14 contains serially connected blocks 38, 36 and 37 whose output is the output of block 14 and is also connected to the second input of multiplication unit 36, the first input of which is connected via comparison circuit 39 and a diode with a relay coil 40. Input block 37 It is connected to the input of block 42, the output of which is through an voltage divider, inverter 41 and diode 43 is connected to a normally closed contact of turnip 40, and through diode 44 to a normally closed contact of relay 40. General contact relay 40 through a voltage divider Inna with the input of the block 38 and the second input (input of the divider) of the block 14. The comparison circuit 39 is a conventional comparator, executed on the Stdsdt trigger.

Control block 8 (Fig. 4) is used to control the process of calculating the coefficients of the denominator of the transfer function of the object under study 1 and the static transfer coefficient. The control unit 8 consists of a test voltage source 16, a second switch 17, a signal delay unit 18, two buttons with normally closed 19 (Reset button) and normally open contacts

20 (Countdown button), relay 22, block

21 forming the control signal.

1231D894

differentiator 24 and latch 23

n 10

,

15

20

25

thirty

35

40

45

50

55

zero level

The test voltage source 16 is designed to supply test voltage of a given level to the input of the object under study 1 when determining the static transmission coefficient K in (1).

The switch 17 is designed to control the operating modes of the device: in position 1, only the coefficient K is determined, and in 2, the coefficients a, and a,. The delay unit 18 serves to delay, at a time t, the moment of obtaining the first result at the outputs of blocks 9 and 10 from the moment of submitting an arbitrary effect to the object under study 1. The delay unit 18 (FIG. 6) consists of a series-connected time relay 30, inverter 31 and circuit 32 match, the second input of which is connected to the input of time relay 30. A time relay circuit 30 is shown in FIG. 7 and assembled on two transistors 33, the collector of one of which through a capacitor 34 is connected to the base of the second. The circuit provides a delay in the appearance of a signal at its output for a time t ,.

The control signal generating unit 21 serves to generate a constant voltage for controlling the units 9 and 10 on the first pulse coming from the output of unit 23, after pressing button 20, the first input of unit 21 is connected via button 19 Reset unit 18 and switch 17 to The source of the test voltage is the control of the input of block 21. When the signal is removed from the first input of block 21, the signal at its output becomes zero. Block 21 is a static trigger assembled on two transistors, whose base circuits include KS chains.

The differentiator 24 serves to obtain the derivative of the input signal of the object under study, and the zero-level clamp 23 to determine the moments of transition of the output signal of the differentiator 24 through zero and is a zero-body executed on the Schmidt trigger.

Blocks 9 and 10 of memory are identical in their structure (FIG. 5) and serve to store at the outputs signal values equal to the values of the coefficients a.

and a

respectively.

They consist of a subtractor 25 of the DC amplifier 28, at the input of which and in the feedback there are the same RC cells, and a relay 29, normally closed contacts of which are included at the input of the DC amplifier 28. Blocks 9 and 10 differ only in the transfer coefficients of subtraction unit 25,

For memory block 9, the transmission coefficients for the first and second inputs of subtraction unit 25 are set to

-

t t

T (- 13,

 - tT

T g

1 7

block 10 memory chi coefficients are set according to

tl g - t /

to.

 t, t t, - t,

A device for determining the parameters of the second order dynamic link operates as follows.

When the switch 17 is set to the first position, a signal is received at the control input of switch 2. Switch 2 triggers and connects a second input to which the test voltage is supplied from the output of the test voltage source 16 to the input of the object under study 1. The object under study 1 processes this signal and a signal appears at its output. By changing the transmission coefficient of the normalizing unit 3, the signal at its output is set equal to the magnitude of the signal supplied from the source 16 of the test voltage. Then, knowing the transfer coefficient of block 3 (K |), the static transfer coefficient of the object under study

-I

In this case, the coefficient of

The problem of a circuit consisting of blocks 1 and 3 is 1.

Then the switch 17 is set to the second position, while reducing the signal from the third input of switch 2 and connecting its first input, to which an arbitrary signal arrives, to the input of the object under study 1. At the same time, the potential jumps through the switch 17 to the input of the signal delay unit 18. When entering in steps

The signal to the input of time relay 30 (Fig. 7) opens the first transistor 33, the capacitor 34 is connected in parallel with the emitter-base transition of the second transistor 33 by a positively charged plate to the base. The second transistor 33 is locked and is in the closed state until the capacitor 34 is discharged through the resistor 35. When the capacitor 34 is discharged, the base current of the second transistor 33 again appears, the last one opens and the signal at its input is not . Thus, the time delay depends on the size of the capacitor 34 and resistor 35. Turning on the time relay 30 together with the logic elements provides a signal at the output of the block 18 and on the button 20 Counting with a delay of time c. The signals from the output of the switch 2 and the scale unit 3 act on the inputs of the transducers of the input 4 and output 5 signals, respectively. As a result of passing these signals through the filters, the first and second outputs of blocks 4 and 5 form signals equal to o, o / p, p, which are fed to the corresponding inputs of the blocks of the first 6 and second 7 dividers of the differential signals, the third inputs of which receive a signal from the output of the normalizing unit 3.

The signals at the outputs of blocks 6 and 7 are determined by formulas (2) taking into account the equality K 1

(2)

m Y - / 3, -2 Y - | 1,

To prevent overloads at the outputs of blocks 6 and 7 at times when, i.e. when dividing by low voltage, including zero, in dividing unit 14, a variable in terms of level limitation of the absolute value of the divider from below is introduced. The unit 14 operates as a known division unit, however, at small values of the dividends, the input of the unit 38 is energized through diodes 43 or 44, the sign of which is determined by the divide sign, for which the comparison circuit 39 is entered into the unit 14. The resistors are adjusted so that the diodes are locked until the voltage at the output of the amplifier 38 drops to a value of 1 / N from the current dividend value, where N is the maximum absolute value. private, corresponding to the scale of block 14. When decreasing divides & l, one of the diodes 43 or 44 opens, the voltage at the output of the amplifier 38 is maintained equal to jjjd / N. When the absolute value of the divide is reached, the bodies up to the value of the 1 / N part of the absolute value of the divided block 14 without a transition process continues normal operation. In this case, the operability of block 14 is ensured when the divider passes through a zero value.

Signals D, and 1) are fed to the first and second inputs of memory blocks 9 and 10, where at the output of block 25 subtraction of them form the difference signals: for block 9 Z, - K D; for block 10 Z K, D, - K P „, which Z 3 h -i

Without any distortions, they are fed to the outputs of blocks 9 and 10 of memory.

The signal from the output of the normalizing unit 3 is fed through the input of the control unit 8 and the differentiator 24 to the input of the latch 23 of the zero level, the output of which jumps from - and to + U abruptly at the moments when its input signal passes through zero. The signal from the output of the latch 23 of the zero level is supplied to the normally open contacts of the relay 22.

When the button 20 is pressed, the countdown occurs, the relay 22, which is blocked by its normally open contact, and when the second signal is closed, in the form of rectangular pulses from the output of the zero-level latch 23 is fed to the input of the control signal-forming unit 21. When the first impulse unit 21 arrives at the second input, it triggers and a constant-sized signal appears at the eio output, which is fed to the winding of the relay 29. Relay 29 triggers and opens its normally closed contacts, while the output of the constant amplifier 28 current signals that were at the outputs of blocks 9 and 10 of memory at the time of opening the contacts of relay 29, Tce at the moment when the derivative of the output signal is equal to 0. At this moment, the signals at the outputs of blocks 9 and 10 of memory are equal to the coefficients a in ( 1), i.e.

and a

ZjV - about a, Z ,, a

When the button 19 is pressed. The reset of the signal from the relay 22 is removed, it opens its contacts and removes the signal from the second input of the block 21 of generating a control signal of the memory blocks, besides, a signal that sets the block 21 to the initial state is removed at its first input. The signals from the output of the blocks 21 and the windings of the relay 22 are removed and the device is ready for a new definition of the transfer function coefficients of the object under study 1, while there is no time t for repeated Samples.

Thus, in the device for determining the parameters of the second-order dynamic-link, the static gain K of the object under study is first determined and then for an arbitrary input signal, at one reading, the coefficients of the transfer function denominator are determined. In this case, compared with the known devices, the time for determining the coefficients a and a is reduced, and it becomes possible to quickly determine the value of a, t. Any points in time, followed by averaging the results, which improves the accuracy and reliability of the results and, in addition to TorOf, allows you to investigate objects with essentially non-stationary parameters of the transfer function.

Claims (1)

Invention Formula A device for determining parameters of a second-order dynamic link, comprising a switch, the output of which serves to connect to the input of a dynamic link, the first input is the input of the device, and the second input is connected to the first output of the control unit, and the normalization unit, the input of which serves to connect to output of the dynamic link, and the output is connected to the input of the output signal converter, characterized in that, in order to increase the speed of determining the parameters of the transmission functions of the object under study, it contains an input signal converter, two delta dividing units and two memory blocks, the first outputs of the input and s output signal converters are connected to the first and second inputs of the first differential dividing unit, respectively, to the first and the second inputs of the second O block dividing difference signals, the output of which is connected to the first. memory inputs; second inputs; connected to the output of the first differential division dividing unit, and the third inputs to the second output of the control unit, whose input is connected to the third inputs of the differential division dividing units and the output of the normalizing unit, and the third output to the third input of the switch, whose output is connected to the converter input the input signal, the outputs of the memory blocks are the outputs of the device. FIG. 2 15 / A 7 fig.Z sixteen 17 13 go lgsh 9,10 27 Hh L2.-L. T FIG. four 27 26 i L PI // city five J J / 2 32 Fig d Fig 7 with t . ЦН- п 5 ff jp - “-