SU1435950A1 - Mass-measuring device - Google Patents

Abstract

The invention can be used to measure the mass of a load transported by belt or other conveyors. The purpose of the invention is to improve the measurement accuracy by stretching the range of the measured value when converting a weight sensor signal. The signal from the weight sensor 1 is fed to the first input of the adder 2, the second (live) input of which is supplied with a voltage from the output of the controlled digital-to-analogue converter i (D / A) 6 with memory proportional to the tare weight. This voltage is determined in calibration mode with a gain factor K Y amplifier 3 with a variable gain factor. If there is no load on the sensor 1, the weight at the output of the adder 2 is zero or a value,. close to zero. When a load appears at the output of the adder 2, a voltage appears that is amplified by the amplifier 3 to k times and is fed to the input of the comparator 4. The other input of the comparator 4 receives an increasing signal from the output of the DAC 5. When the values of the signals at both inputs coincide The comparator 4 is activated and in the microprocessor computing unit 7 a code N is recorded, which is supplied at this moment to the input of the DAC 5, which is proportional to the signal from the weight sensor 1. The gain factor K for amplifier 3 in the measurement mode is calculated in microprocessor computing unit 7 and is taken so that the useful signal of the weight sensor 1 remaining after compensation of the tare mass is fully extended on the scale of the input code of the DAC 5, 2 or 11. (4 & E3s: a

Description

The invention relates to a non-measuring technique and can be used to measure the mass of a conveyor belt or other conveyors, in continuous metering devices with analog gauge sensors.

The purpose of the invention is to increase the accuracy of the measurement bridge due to the stretching of the range of the measured value during the conversion of the sensor signal, weight, I In FIG. 1 shows the scheme of the device- jCTBa; in fig. 2 a, fi are the time diagrams of the operation of the device, respectively, but in the mode of calibration and measurement of the mass.

The device contains an analog | weight sensor 1, an adder 2, an amplifier 3 with a variable gain factor; HHHj comparator 4, an analog-to-analog converter (D / A converter) 5, controllable; 11Д11 6 with an element of us., Microprocessor computing unit 7,: equipped with an input-output interface 8-- yes, a weighing result indicator 9: none and a conveyor speed pulse sensor 10,

 The device works as follows.

 The operation of the device is carried out by IB in two modes: Taring and Iz-: measurement.

: In the Taring mode (Fig. 2a) .i, the voltage U is determined (U: which is then fed to the second input of the adder 2 to compensate for the tare weight, and the initial range of the measured value is calculated when converting the sensor signal 1. Weight. For this, the signal from sensor 1 is weight and, K, g (t) i, where K, is the conversion factor; g (t) is the linear mass, is fed to the first input of the adder 2 to the second input of the adder 2 to this no voltage is applied. The transfer coefficient of the adder 2 at the first input is equal to e The distance and, consequently, the voltage at the output of the adder 2 completely coincides with the signal of the weight sensor 1, i.e. 11 1), (FIG. 2). A signal is sent to the control input of the amplifier 3 from the microprocessor computing unit 7 via the input-output interface 8. The gain of the amplifier 3 is equal to the initial K, Voltage IU

,

 amplifier output

0

five

five

0

five

arrives at the first input of the comparator -4,

At time t (Fig. 2), the information inputs 11AP 5 and 6 of the microprocessor computing unit 7 through the input-output interface 8 with a frequency clocked by the generator built into the microprocessor computing unit 7 are sequentially incremented code N

(Oj 1,2j35. "S,) 2 the result of the output of TsA11 5 is a voltage proportional to the code N (Us). This voltage is applied to another input, comparator 4 ..

At time ti (Fig. 2), the continuously increasing voltage U becomes equal to the voltage at the first input of the comparator 4 and the comparator 4 is triggered. At the same time, the pulse from the output of the comparator 4 enters the microprocessor computing unit 7, the N code at the information inputs of the DAC 5 and 6 stops growing, and the RAM of the microprocessor computing unit 7 stores the code N | J proportional to the tare weight (voltage U of the weight sensor 1).

At time tj, the microprocessor computing unit 7, via the input-output interface 8, sends a signal to the send input of the controlled DAC 6, which in the memory of the digitalisable DAC 6 stores the code Nj. And at the output of the controlled DAC 6 voltage and. (U KpN). This voltage is fed to the second input of the adder 2 (the transmission coefficient over this input is also equal to 1) so that the voltage at the output of the adder 2 is equal to the difference of the voltages at its inputs.

and,

t "e

Mator Time 2

R

and o therefore at the moment

H

output voltage sum 50

u.Ui- and, - and about

and comparator 4 (the N code on the information inputs of the DAC 5 and 6 is reset, the signals on the inputs of -Comparator 4 are absent).

Then, in the microprocessor computing unit 7, the initial range of change of the measured signal is calculated during the conversion of the signal from the weight sensor 1

. SM c-, to N - N.,

where N is the maximum allowed

DAC input code 5. To more accurately determine the voltage U {, tare mass compensation, calibration cycles t under the control of the microprocessor computing unit 7 can be performed several times (for example, for a full run of the conveyor belt) and then in the microprocessor computing unit 7

the mean value of N is determined.

 V t n Z- N., which is set to

i 1

information input controlled 15 DAC 6,

The Measurement mode is immediately preceded by the determination in the microprocessor vyisolitelnyy block 7 of the gain factor K, and the corresponding control signal for amplifier 3, which provide the extension of the measurement range

useful signal sensor 1 weight U. ,,

,, on the full scale of the input code.

CAA 5, This ensures high accuracy in measuring the value of the signal AND of the weight sensor 1.

The value 4Nyj can be assumed to be equal to N ,,, a «с (fe, 11 К1 0), However, usually the tare weight is not fully compensated (U is taken several times the voltage 11), because otherwise even a not - significant fluctuation of the tare weight may lead to the transition of the operation of the mator 2, amplifier 3, comparator A c. area of negative tension. In this case, the value / IN

25

thirty

35

40

defined as

4N

mzm

   g

Then the coefficient K of amplifier 3 for the Measurement mode is defined as

m ttkt

((,, I - ,,

B

iji max t

For the calculated value of the coefficient K y, the microprocessor computing unit 7 generates a control signal which is fed to the control input of the amplifier 3 via the input-output interface 8.

In the Measurement mode (Fig. 2 b), the pulses from the sensor 1 O of the conveyor speed with frequency f |. (T), proportional to the speed of movement of the conveyor belt, through the input-output interface 8 enter the microprocessor computing unit 7, in which the period T, the arrival of pulses 1 eV is determined by the velocity Vcp .; dv1-gzheni tape on the interval T.i,

V T / T

 Wed i- / j- with. one

where L is the length of the way, during the passage of which by the conveyor belt the sensor 10 of the speed of the conveyor generates another impulse.

The signal from the weight sensor 1 is fed to the first input of the adder 2, to the second (subtractive) input of the adder 2, voltage 1b U is applied, C output of the adder 2 voltage l, j b, P is fed to the input of amplifier 3; where it is amplified K times, and then fed to the first input of comparator 4.

at time t (a microprocessor computing unit 7 received a pulse from the speedometer sensor 10), the information inputs of the AP 5 through the input / output interface 8 from the microprocessor computing unit 7 begin to sequentially increment N codes (0.1 5.2,. .., N). At the output of 11АП 5, the voltage appears

Uj KpN, where Kp is the conversion coefficient, which is fed to another input of comparator 4. With the coincidence of the voltages II j and at the inputs of the comparator 4 (time

t) a high voltage level appears at its output, which through the I / O interface 8 is fixed in microprocessor computing unit 7. At the same time, the RAM code of the microprocessor computing unit 7 records the value of N, which is proportional to the signal of the weight sensor 1 at the moment (t ) and time dt. measuring (converting) sensor signal50

55

ka 1 weight, after which the N code on the information inputs of the DAC 5 is reset, and then begins to increase sequentially (N - O, 1, 2,.,., Nj, Bkc), i.e. a new cycle (dt.) of measuring the signal of the weight sensor 1 begins. At the same time, in the microprocessor computing unit 7, the product N., dt, is computed and stored in a separate memory cell.

As the N2 code increases, the voltage (2Ne U on the DAC 5 output code and when it reaches the voltage Uj at the output of the amplifier 3, the comparator 4 is triggered again through the input-output interface 8 - the numeral block 7j in the cells of the RAM of the microprocessor computing 7 is stored the values of N

 2

broca

 and the microprocessor computer ny unit 7 begins the following cycle n | transform the signal of weight B1 code. At the same time, in the microprocessor block 7, the summation of the N-.dty production is performed with a value that is less than crawled in the previous Jmeren cycle.

; At time t, (FIG. 2 b) h | Through the input-output interface 8, an impulse arrives at the microprocessor vyislitelny-nrgo block 7 in the course of the conveyor speed, which is produced in the microprocessor computing unit 7 calculating the average velocity .- and multiplying the value of Vj, p; on accumulation- m

The total amount is zl N.dt., where is the number J J

the number of measurement (conversion) cycles S, laid down during the time of T.,

, As a result, the mass of the cargo is M,, re-Eeschenna conveyor for time; is defined as m

M,

,, N..t.

.J f)

where K, is the conversion factor,

 The resulting M. value is stored in the RAM of the microprocessor computing unit. 7 for the subsequent summation with the following numbered partial masses

Thus, a microprocessor-based computer unit 7, after the arrival of the next impulse from the speed sensor 10, processes information during the previous measurement interval T. e Tg, compute the speed of the tape Vcp.i for determining the partial mass M- and accumulating p e 3 ult a b a s in the seizure. At the same time continue to carry out the measurement of the j-x signal values of the sensor 1

Since with m 1 miBanie calculated values of the masses produced periodi ™

necKjti with frequency f с j, then the resultant weight of the cargo Мр moved by the conveyor during the weighing time € is equal to

e m

Mr K and

cp.i

 ; 3t.,

J--

where 1 is the number of impulses of the sensor 11 of the speed of the conveyor received at the input of the microprocessor computing unit 7 in time E

(5 y t.)

 B / -I- i / o

The result of calculating the mass of the load Мр from the microprocessor computing unit 7 through the input-output interface 8 enters the indicator

9 of the weighing result, according to the indications of which it is possible to judge the weight of the load5 displaced by the conveyor, or it may touch actuators to control the dosing processor of the material transported by the conveyor,

about the formula

A device for measuring mass, containing a microprocessor computing unit with an indicator, a weight sensor and a pulse speed sensor of the conveyor, connected to one of

inputs of a microprocessor computing unit, characterized in that, in order to improve measurement accuracy by extending the range of the measured value,

A series connected adder, an amplifier with variable gain, and a comparator, as well as two digital-to-analog converters J, one of which

: 1TG1vravlyaem with a memory element, the first input of the adder is connected to the weight sensor, and the second input - to the output of a controlled digital-analog converter, the output of the digital-analog converter is connected to the second input of the comparator, the output of which is connected to the second input of a microprocessor computing unit, the first output of which is connected to the control input of the amplifier to the second output is the control input of the controlled digital-to-analog converter, and the information output of the microprocessor-based calculator 11435950

The unit is connected to the input by a digital input of a controlled analogue analogue converter and a digital-analogue analogue converter.

Claims (1)

Claim A mass measuring device comprising a microprocessor computing unit with an indicator, a weight sensor and a pulse conveyor speed sensor connected to one of the inputs of a microprocessor computing unit, characterized in that, in order to increase the measurement accuracy by stretching the range of the measured value, it introduces series-connected adder, variable-gain amplifier and comparator, as well as two digital-to-analog converters, one of which is controlled with a memory element moreover, the first input of the adder is connected to the weight sensor, and the second input is connected to the output of the controlled digital-to-analog converter, the output of the digital-to-analog converter is connected to the second input of the comparator, the output of which is connected to the second input of the microprocessor computing unit, to the first output of which the control input of the amplifier is connected, to the second the output is the control input of the controlled digital-to-analog converter, and the information output of the microprocessor-based computing unit 1435950 is connected to the input of the digital-to-digital input of the controlled analog-to-analog converter;