SU1725233A1 - Device for checking objects - Google Patents

Abstract

The invention relates to automation and computer technology and can be used to assess the technical condition of a monitored object and to predict the time it takes to prevent it. The purpose of the invention is to improve the accuracy and reliability of the control. The device contains a group of sensors 1, switch 2, normalization unit 3, analog-digital converter 4, drive 5, setting unit 6 for extrapolating measurement results, setting unit 10 for evaluating measurement results and setting unit for 14 standards, units 7, 11 multiply

Description

nor, accumulating adders 8, 12, groups of elements And 9,13,16, subtraction unit 15, indicator 17, clock pulse generator 18, frequency divider 19 and interference suppression block group 20. The device provides filtering of noise in the input signal using automatic adjustment. 1 hp f-ly, 4 ill., 1 tab.

The invention relates to automation and computer technology and can be used to assess the technical state of a controlled object and to predict the time of its withdrawal for prevention.

A device for monitoring the technical state of radio-electronic objects is known, comprising parameter sensors, a switch, a normalizer, an analog-to-digital converter (ADC), first and second multiplication blocks, keys from the first to seventh, first and second summation blocks, algebraic summation block, memory block ti, unit for setting standards, unit for setting smoothing factors, shift register, display unit, clock generator and frequency divider. In this device, the method of sequential exponential smoothing of parameters for calculating the estimated and extrapolated value of 1 is instrumented.

The disadvantages of the known device are relatively low accuracy and reliability of the control, which is caused by the significant influence of the noise level (measurement errors) on the quality of the control.

A digital-to-analog converter is known, comprising a current generator, a current switch, a summing operational amplifier and a noise suppression circuit consisting of a differentiating circuit, a frequency-compensated divider and an operational amplifier 2.

A disadvantage of the known converter is the low interference suppression efficiency due to the lack of adaptation (operational tuning) of the circuit parameters to changes in the frequency spectra of the useful signal and interference, and the degree of interference suppression in this device is very sensitive to the circuit parameters (sharp tuning is required).

In addition, this scheme cannot be used to suppress interference on several independent information inputs with arbitrary amplitude-frequency spectra of the useful signal and interference in each of the inputs.

The closest to the present invention is a device for monitoring electronic objects, containing a group of sensors, a switch, a normalization unit, an ADC, a drive, two coefficient factors, two multiplication units, two accumulating adders, three groups of elements And,

master of standards, subtraction unit, indicator, clock pulse generator, frequency divider 3.

The disadvantage of this device is the substantial dependence of the reliability and accuracy of the control on the noise level when measuring the parameters of the object.

The purpose of the invention is to improve the accuracy and reliability of the control due to the filtering of noise in the input signal with

using automatic tweaking.

The goal is achieved by the fact that a device for monitoring electronic objects containing a group of sensors

switch, normalization unit, ADC, drive, setting factors of extrapolation coefficients and evaluation of measurement results, first and second multiplication units, first and second accumulating adders, three

groups of elements And, master of standards, subtraction unit, indicator, clock pulse generator, frequency divider, a group of interference suppression blocks by the number of objects monitored, and

each interference suppression unit contains. Noise extraction node, delay element, subtraction node, residual noise level measurement node and amplitude-frequency characteristic adjustment (AFC) node

filter.

Figure 1 presents the block diagram of the device; figure 2 - diagram of the synchronization operation of the blocks of the device; on fig.Z - graphs of the frequency response, the spectrum of the useful signal and

interference spectrum; 4 shows the transfer function and the logarithmic frequency response of the differentiating chain.

The device contains a group of sensors 1, switch 2, block 3 normalization, analog-digital converter 4, drive 5, unit 6 of extrapolation coefficients of measurement results, first multiplication unit 7, first accumulating adder 8, first group 9 of elements I, unit 10 of evaluation factors measurement results, the second multiplication unit 11, the second accumulating adder 12, the second group of 13 elements AND, the setting unit of 14 standards, the subtraction unit 15, the third group of 16 elements AND, the indicator 17, the generator 18 clock pulses, the frequency divider 19 a group of interference suppression units 20 by the number of objects to be monitored, each interference suppression unit comprising an interference elimination unit 21, a delay element 22, a subtraction unit 23, a residual noise level measurement unit 24, a frequency response control unit 25.

The device works as follows

The generator 18 and divider 19 perform the functions of the device synchronizer. Synchronizer generates signals

. {A} Ai, A2A | ; {C} Ci, C2Cm;

{S} -81,82,83,84.

which determine the sequence of processing information about the system parameters and synchronize the operation of the device nodes. The sensor group is a set of LTTI parameter measuring sensors, information from which, in analog form, in the form of a varying level (amplitude) of current (voltage) is fed to interference suppression units.

The input signal Uj1 from the J-th sensor is an additive mixture of the useful signal Vj

and interference Јj

 +.

At the same time, random processes for different parameters are independent, and the measurement errors of each of the parameters at an arbitrary time point are distributed according to the normal law with zero mathematical expectations and known dispersions.

The input signal Uj1 is fed to the interference elimination unit 21 and the delay element 22. Node 21 serves to

distortion of the noise выделитьj, without missing the useful signal Vj. The selective properties of block 21 are based on the difference in the spectra of the useful signal and

interference. If the spectrum of the desired signal is grouped in the low-frequency region (Fig. 3), then the interference spectrum is grouped mainly in the high-frequency region. The amplitude-frequency characteristic (AFC) of block 21 should ensure the smooth passage of interference only. In the simplest case, a differentiation circuit RC with automatically controlled capacitance C can be used as a fluctuation isolation unit. Figure 4 shows the circuit diagram, the transfer function and the logarithmic frequency response of the differentiating circuit. From the expression for the transfer function it can be seen that the selection of the nominal values of R and C can provide an arbitrary value of the cut-off frequency ufc (Fig. 3). Since, in the general case, the useful signals of different measured parameters have different spectra, the values of RC chains for different inputs are different. In subtraction unit 23, a signal Uj is formed, which is close to the difference of analog signals.

Uj "uj1-Јj1.

The delay element 22 serves to delay the input signal by a time equal to the delay of the output signal of the node 21 relative to the input signal. The delay is due to the inertial properties of the RC differentiating circuit and the larger, the greater the values of the values of R and C (approximately 3RC). The delay elements should be adjustable; at the device setup stage, a delay should be set for each of the monitored parameters.

the temporal combination of the Ј / and Uj signals (remember that both signals are continuous analog). An indicator of the correct setting can be the achievement of the minimum level of interference at the output of the subtracting unit 23.

The signal Uj at the output of the interference suppression unit 20 differs from the useful signal Vj by a random value fj, which, like

the initial noise in §1 has a zero expectation, but its dispersion is substantially less

S & zm "(%

; ISM

Nodes 24 and 25 represent a feedback loop that serves to fine-tune auto-tuning in order to minimize the value of

. In this case, node 24 measures the noise level taking into account the phase of deviation from a certain average level, the output voltage from the output of node 24 in node 25 is amplified, transformed into the desired shape and through the actuator directly acts on the adjustable element of the node 21 of the interference suppression - filter frequency response .

If used as a differentiating chain unit 21, the variable block may be variable capacitance C. For these purposes, varicaps of types KVS-111, KV-102, and others with a capacity tuning range of up to several hundred picofarads can be used. In general, the implementation of the auto-tuning circuit at nodes 24 and 25 is similar to the well-known noise automatic gain control circuits (FPA), widely used in radio circuits and measurement technology.

Thus, the purpose of block 20 is to substantially reduce the level of interference in the input signal or, more precisely, to reduce the variance of the interfering component (measurement error) in the input signal.

A node 23 for subtracting two analog values is advisable to implement on the basis of an operational amplifier with a large gain (at least 10,000) and a negative feedback circuit through a resistor. The two input resistors of the opamp are fed down and subtracted. By selecting the values of the input resistors, this compensates for the difference in the degree of attenuation of the signals as they pass through the blocks 21 and 22.

Switch 2 performs interrogation of the outputs Lm of the interference suppression units one by one and consists of Lm electronic selection circuits, each of which receives signals: from its own interference suppression unit; polling control signals {A} and {C}; sync signals $ 2. The switch is made on chips of the type KIO KT 2 or KP 590 KN 2. The normalization unit 3 carries out the representation of various electrical quantities of the objects being monitored to a certain voltage scale and is implemented on an operational amplifier with a variable gain factor. The latter is automatically set by the control signals {A}, {C} in the range of the signal S2. The change in the gain factor is made by switching the resistors in the feedback circuit of the amplifier. A / D converter 4 converts the voltage from the output of the normalizer to a digital binary code. The drive 5 records and stores the values of the last N measurements for each of the m parameters of all L control objects. The drive contains L-m -N memory cells. Writing and reading words in the accumulator is controlled by the signals {A}, {C}, $ 2 and 5h of the frequency divider 19.

In block 11 of the multiplication and the second accumulating adder 12, the estimated value of the j-ro parameter Uj is calculated

according to the expression

TO

2, aiUij, -i 1, N; j 1, m,

i 1

(one)

where N is the sample size (number of measurements);

Uij is the result of the 1st measurement of the j-ro parameter;

but; - The coefficient for evaluating the result of i-ro measurement.

In multiplication unit 7 and in the first accumulating adder 8, the extrapolated value j-ro is calculated

parameter Uj9 in accordance with the expression

u.-i

and

  one

aiaUij; i 1, N; j i, m, (2)

where ais is the extrapolation coefficient of the result of the i-ro measurement,

The values of the coefficients ai and for each 1st dimension are calculated previously based on the expressions

40

ai

61 -2N -2 (N + 1) N

- 3 (N + 2) (N + 3) -2l (4N + 7) + 10l2 3 | eN (N-1) (N-2)

The coefficients ai are used for recording and storing the factors 10 and 6, respectively, which perform the functions of semi-permanent memory devices with a capacity of N words each.

In block 15, the subtraction calculates the magnitudes and signs of the deviations D of the monitored parameters Uj from their nominal values (standards) UHj

55

AJ Uj - UHj.

(3)

The values of the nominal values UHj are stored in the sensor 14 of the standards and the signals {A} and {C} of the frequency divider 19 are output to the subtraction unit 15. The reference setter is a permanent storage capacity of LTTI memory cells.

Indicator 17 is used to visually assess control results. For each parameter, the indicator displays the parameter number of the object, the upper and lower tolerances of the deviation from the nominal, the current deviations of the estimated value of D- and the predicted value.

By calculating the estimated value of the parameter Uj by expression (1), it is possible to reduce the variance at the output of the interference suppression unit 20 to the following variances at the output of the adder 12:

if the parameter in time is described by a polynomial of the first degree

 2 (2N - 1). ol-imism NVN + 1f if the parameter in time is described by a polynomial of the second degree

LZ-P2. 3 (3N2-3N + 2) ,, 02-OYzm N (N + 1) (iM + 2) W

From expressions (4) and (5), it follows that with increasing sample size N (N 3), the error dispersion decreases.

After conversion from the output of the A / D converter 4, the binary code of the measurement result j-ro of the parameter of the 1st object is recorded in the accumulator 5, where it is stored for N adjacent measurement cycles. In the cycle, the reading of all N measured parameter values from the accumulator 5 into blocks 11 and 7 of multiplication occurs. At the same time, from the setting unit 10 to the second multiplication unit 11, the values of the coefficient ai are read, and from the setting unit 6 to the first multiplication unit 7 - the values of the coefficients. The products of arUij and ais Uij obtained at the outputs of the multipliers, according to expressions (1) and (2), are respectively added to accumulating summers 12 and 8.

In cycle $ 4, the estimated value of the parameter Uj from the output of the adder 12 through the second cadaver of the elements And 13 is output to the subtraction unit 15, where in accordance with expression (3) it is compared with its reference value UHJ read from the unit of 14 standards.

The extrapolated value of the parameter Ujs from the output of the first accumulating adder 8 through the first group of elements And 9 is transmitted to the indicator 17, where it is stored, converted into analogue form and in the next clock cycle Si is supplied to the display. In this tact through

five

ten

15

20

25

thirty

35 40 45

50

55.

the third group of elements 16 on the indicator 17 is taken the value AJ, which is displayed after a similar conversion.

Simultaneously with these values, the boundaries of the permissible value of the parameter are formed, which are formed in the indicator 17 itself.

As setters (blocks 6, 10, 14), it is advisable to use a constant memory device, which makes it possible to reduce the access time (for example, a ROM on chips K 1607 RF 1, K 1801 PE 1, K 1809 PE 1, K 573 RF 3, K 501 PE 1 P). As a drive (block 5), it is possible to use microcircuits 132 RU 1.185RU4, 185 RU 5, 541 RU 1, matrices of RAM К 176 РМ 1, КР507РМ 1.

As a block 15 subtraction, it is advisable to use chips 155 IM 1, 155 IM 2, 134 IM 5, K 176 IM 1, 564 IM 1, as accumulating adders (blocks 8, 12) of the microcircuit K 502 IC 1.

As a delay element (block 22), commercially available delay lines of the following types can be used: MLV-1- 600, MLA-0.5-600, MLS-1-1200. MLS-0.5-100. All of these delay lines allow changing the delay time with a resolution of 0.1 or 0.2 µs.

As a base object, having the same structure and function as the prototype, the CC-10 monitoring and diagnostics system can be adopted, manufactured by the Danish company STL for marine diesel engines.

The technical effect of using the proposed device is to improve the accuracy and reliability of the control by filtering noise in the input signal. To quantify the gain, it is necessary to compare the value of the variances of the noise components at the input and output of the device. For the sake of definiteness, we assume that a differentiating circuit is used as the noise isolation node 21.

If the dispersion of interference (measurement errors) at the device input is taken as 1, the use of digital processing of measurement results using the fixed sample size method reduces the error variance of the estimated parameter values to 0.32-0.8. The specified range corresponds to the values of N from 5 to 10 when describing a parameter by polynomials of the first and second degree. Thus, the use of this system in the base object makes it possible to reduce the variance by an average of 2 times.

In the proposed device, the digital filtering is essentially unchanged, characteristic of the base object, and the associated decrease in dispersion is on average 2 times. In the proposed device, the input signal is additionally subjected to analog noise filtering. Based on the principle of operation of the interference suppression unit 20, the degree of interference suppression is determined by how cleanly the interference isolation unit 21 will reproduce the interference and will not miss the useful signal. Based on the frequency characteristics of the differentiating circuit, it can be argued that part of the interference spectrum lying along the frequency axis of the cutoff frequency Ok in is practically

The cop

reproduced without interference

L (y) 20lg-y- 20lg 1 0,

from where

AH 1.

It is believed that the main energy of the spectrum of the useful signal lies in the range of 1

that 0 a)

RC

Since for a given frequency range, the ratio

CSO) 20 Ig K + 20 Ig. the results of the frequency response values for the boundaries and the middle of this range can be tabulated

The table shows that if the spectrum of the useful signal has a uniform distribution in the frequency range from 0 to 1

-57G- (has a flat top), then weakened

The energy of the useful signal will decrease by an average of 2 times. However, this estimate was obtained with a large margin, since the spectra of real useful signals are close to the bell-shaped form and are grouped mainly in the low-frequency region. If you accept that in the frequency range from 0 to

Op „80% of the energy of spect lKU is concentrated

the useful signal, the gain will be about 5 times.

If we assume that blocks 22 and 23 have wide bandwidths that allow to reproduce input signals without distortion (and this is the case in practice), then in general we can assume that the use of analog filtering reduces the dispersion of noise by 2–5 times, but

use of the proposed device, respectively, 4-10 times. Achieve these numbers can be subject to proper functioning of the system of self-tuning. Significant increase in calculation accuracy

0 estimated and extrapolated values will lead to a decrease in the number of erroneous decisions when monitoring the current technical condition of objects, and, consequently, will increase the reliability of the control.

five

Claims (2)

Claim 1. Device for controlling objects containing a group of sensors, a switch, a normalization unit, an analog-to-digital converter, an accumulator, factors setting factors for evaluating measurement results and extrapolation of measurement results, two multiplication units, two accumulating adders, three groups of elements I, master gauge 5 standards, a subtraction unit, an indicator, a clock generator and a frequency divider, the switch output is connected to the information input of the normalizer, the output of which is connected to the information input of the analog-digital converter, the output of which is connected to the information input of the accumulator, which output is connected to the inputs of the first multipliers of two multipliers, input 5 of the second multiplier of the first multiplication unit is connected to the output of the setpoint of extrapolation coefficients of measurement results, and the output to the information input of the first accumulating totalizer, the output of which is connected to the first group of inputs of the first group of elements AND, the outputs of which are associated with the first group of information inputs of the indicator , the input of the second factor of the second block of the smart 5 is connected to the output of the set factor for the evaluation of measurement results, and the output to the information input of the second accumulating adder, you od which is connected with the first group of inputs vto0 swarm group of AND gates, whose outputs are coupled to the minuend input of the subtractor unit, which is subtrahend input coupled to the output setpoint standards, and the outputs - the first inputs of the third group 5 groups of elements And, the outputs of which are connected to the second group of information inputs of the indicator, the output of the clock generator is connected to the input of a frequency divider, the outputs of which are connected to the control inputs of the switch, a normalizer, analog-to-digital converter, with inputs for controlling writing and reading the accumulator, unit for extrapolation coefficients of measurement results, unit for evaluation factors for measurement results, unit for standards, with control inputs of the indicator and with the second groups of inputs of three groups of I elements, distinguished by , in order to increase the accuracy and reliability of control by filtering noise in the input signal using automatic adjustment, a group of interference suppression blocks has been entered into it according to the number of monitored objects whose information inputs are connected to the sensor outputs, and the outputs are connected to the information inputs of the switch, the corresponding control output of the frequency divider is connected to the synchronous input, contains an interference elimination node, delay element, subtraction node, measurement node A, A, C, S, lA, pt P P  p p p p p p p p p p t b fas, П П П П П П П П П П П П П t A .d pp pn J 6.10) Вц (6л.9, to ,, n) p p p p p pp pp n n n l DQ.DCL the residual noise level and the filter amplitude-frequency characteristic control node, the information input of the interference suppression unit is connected to the input of the delay element and the information input of the interference extraction node, the output of which is connected to the input of the subtracted subtraction node, the input of which is decremented is related to the output of the delay element, output the subtraction node is connected to the output of the noise suppression unit and to the input of the node measuring the residual noise level, the output of which is connected to the input of the amplitude-frequency control node sticks filter the output of which is connected to the control input of the interference separation node, the synchronous input of the interference suppression unit is connected to the synchronization input of the subtraction node. 2. The device according to claim 1, wherein the interfering node is implemented as a controlled high-frequency RC filter. .d pp pn n n n Fig.Ј l DQ.DCL Fig.Z FIG.