SU1484331A1 - Apparatus for automatic monitoring of soil moisture content - Google Patents

Abstract

The invention relates to measuring equipment in agriculture and can be used for continuous automatic control of soil moisture during the operation of agricultural machines. The purpose of the invention is to improve the accuracy of control. The device contains the main 1 and reference 2 capacitive transducers, one of which contains a dielectric plate with a previously known dielectric constant ε _G included in the circuits of the working generators 3, 4. Changing the soil moisture content entails changing its dielectric constant ε _X and ε _X = ε _G (F ₂ -F001) / F001. The output frequencies F001 and F002 of the generators 3, 4 are fed to the input of the frequency quadrants 5, 6. D - trigger 7 performs the subtraction of the squares of the frequencies. The division of the difference of squares of frequencies by the square of frequency is carried out by a square-frequency conversion circuit into a code consisting of RS flip-flop 17, elements AND 8, 9, 22, a binary counter 10, a code-frequency converter 11, counter 23 and a dividing circuit consisting from the reverse counter 12, RS - trigger 13, drivers 14, 15, memory register 16, inverter 18, binary-decimal counter 19, AND elements 20 and reference oscillator 21. The readings of the display unit 24 correspond to the numerical value of the soil moisture Capacity counter 23. 5 Il.

Description

The invention relates to a measurement technique, in particular, to electronic soil moisture meters, and can be used in agriculture for measuring soil moisture during soil electrophysical treatment in field conditions.

The purpose of the invention is to improve the accuracy of continuous monitoring of soil moisture.

FIG. 1 is a schematic of the device for automatic soil moisture control in FIG. 2 - soil moisture converters and their installation on the cultivator paw of an agricultural machine in FIG. 3 shows section A-A in FIG. 2J in FIG. 4 - the same, top view; FIG. 5 - time diagram of the operation of the device blocks.

The device contain the main 1 (capacity C.) and the reference 2 (capacity

U2

a) capacitive transducers hum included in the circuits of the corresponding generators 3 and 4, while the capacitive transducers are made according to the differential scheme. The outputs of the generators 3 and 4 are connected to the inputs of the squares 5 and 6 frequency. The output of the frequency quadrant 5 is connected to the C-input of the D-flip-flop 7 and the first input of the first element And 8. The output of the quadrant 6 frequency is connected to the D-input of the D-flip-flop 7, the direct output of which is connected to the first input of the second element And 9. The output of the first element And 8 is connected to the C-input of the binary counter 10, the information outputs of which are connected to the D-inputs of the converter 11 code - frequency. The output of the second element And 9 is connected to the summing input of the reversible counter, 12, the subtracting input of which is connected to the output of the converter code - frequency and the S-input of the first RS-flip-flop 13. The output of the reversing counter 12 is connected to the input of the first converter 14 and the R-input

Capacitive transducers are placed on the working body of an agricultural machine, for example, on a cultivator leg (Fig. 2). The transducers are mounted on the mounting paw 25 of the cultivator 26, on the inner side of which there is a block of capacitive transducers 1 and 2 with generators 3 and 4. The block of capacitive transducers contains a central electrode 27, two identical side electrodes 28 and 29, fused electrodes 30 and 31. Under One of the side electrodes 29 is a dielectric layer 32 with a known dielectric constant Ea. The electrodes are separated from the ground surface by a dielectric layer 33. Capacitance C 2 introduced into the construction with a plate inserted into it with a previously known dielectric constant allows one to obtain additional information not only on the measured value of humidity, but also on the errors that can be made when measuring x, and thereby eliminate these errors from the measurement result. In this case, the change in the desired value - the dielectric constant of the soil 6X, which is a function of the moisture meter 10. The output of the first formed the content, such

The technical unit 14 is connected to the input of the second driver 15 and the R input of the trigger 13 and the V input of the memory register 16. The output of the second driver 15 is connected to the S-input of the second RS-flip-flop 17 and through the inverter 18 with the R-input of the reversing counter 12 and the R-input of the binary-decimal counter 19, the information outputs of which are co-parameters of soil as temperature, density, salinity, etc. d. The introduction of capacitance C makes it possible to express the desired dielectric constant of 55 soils x in the form of relative

differences in the squares of the frequencies supplied by the working generators 3 and 4, as well as the influence of such soil parameters as temperature, density and

dinene with a D-input of the memory register 16, and a C-input with the output of the third element I 20 whose first input is connected to the output of the generator 21

the reference frequency, the C-input of the converter 11 and the first input of the fourth AND 22 circuit. The second input of the AND 20 circuit is connected to the direct output RS-flip-flop 13. The direct output of the RS flip-flop 17 is connected to the second input of the And 22 element and the second inputs of the first 8 and second 9 of the And and R circuits of the converter 11. The output of the fourth And 22 element is connected via an additional binary counter 23 to the R input of the second trigger 17. The outputs of the memory register 16 are connected to the dictation unit 24.

in5

0

five

0

five

0

Capacitive transducers are placed on the working body of an agricultural machine, for example, on a cultivator leg (Fig. 2). The transducers are mounted on the mounting paw 25 of the cultivator 26, on the inner side of which there is a block of capacitive transducers 1 and 2 with generators 3 and 4. The block of capacitive transducers contains a central electrode 27, two identical side electrodes 28 and 29, fused electrodes 30 and 31. Under one From the side electrodes 29 there is a dielectric layer 32 with a known dielectric constant Ea. The electrodes are separated from the ground surface by a dielectric layer 33. Capacitance C 2 introduced into the construction with a plate inserted into it with a previously known dielectric constant allows one to obtain additional information not only about the measured value of humidity, but also about the errors allowed to be measured and thereby eliminate these errors from the measurement result. In this case, the change in the desired value - the dielectric constant of the soil 6X, which is a function of moisture content, is influenced by such

soil parameters like temperature, density, salinity, etc. The introduction of capacitance C makes it possible to express the desired dielectric constant of the soil x in the form of relative

differences in the squares of frequencies from working generators 3 and 4, as well as the influence of such soil parameters as temperature, density and

bodies shown in FIG. 2, can be found by the formula:

with Јх 7 1п 4 Ъ

514

the salinity in tanks C and C2 is the same, the resulting expression depends only on the soil moisture.

The guard electrode is located in the plane of the working bodies. An electric field is formed between the central electrode 27 and the electrodes 28 and 29 and 30, having the same voltage, consisting of two areas, each of which is associated with a voltage on the electrodes 28 and 29, respectively. To the measuring side electrodes 28 (29), the current flows only through the outer zone between the electrodes, and therefore the changes occurring in the inner zone between the electrodes 27 and 30 (31) are practically ignored by the converter. In the event that there is no guard electrode (30 and 31) in the converter, the internal zone in which the lines of force run almost along the surface of the converter (between electrodes 27 and 30, 27 and 31) causes a strong sensitivity of the converter to the gap between the converter and measured object (ground). This is due to the fact that when the measured object moves away from the surface of the electrodes, gentle field lines are drawn from it, which maximally polarize the soil. The guard electrodes 30 and 31, which draws on current flowing through the inner zone, eliminate the main cause of the sensitivity of the transducer to the air gap.

The device works as follows.

When tilling the soil, the working part of the cultivator 26 (Fig. 2) loosens the topsoil, while the block of capacitive transducers 1 and 2 are in mechanical contact with the soil surface under the inner plane of the cultivator.

Approximate transform capacity

eaЈ i i /

 city- In. four --

CQ + CX1ГЬ

- the length of one electrode; - half the distance between the outer edges of the electrodes;

6

b - half the distance between

inner edges of the electrodes;

The standard dielectric constant;

Al is the dielectric constant of dielectric 31. The working capacitance Cr is determined by

10 according to the formula

from (-Јх

In 4 g15

Denote k -

ln 4 -, then b

C, kg,

If working capacitance C is defined as the sum of two series-connected capacitances with dielectric constant b and Јa,

then

.

 3

x Ј

The output frequency of the working generators 1 and 2 is inversely proportional to the capacitance of the converter, and hence the dielectric constant of the soil

Ј4

2 "G

4Ш1

2fr LCT

(ABOUT

2 / V h

L

(2)

 G6

where L is the oscillatory inductance

generator circuit. Erect both sides of the equations for Ј4 and square and solve them with respect to Јy, get

f2 f2 b, -B, O)

i

The implementation of dependency (G) is carried out using the elements

5-23 of the block diagram shown in FIG. one.

The output frequency of the working generators 3 and 4 is fed to the input of the squares 5 and 6 frequency. Using the D-flip-flop 7, subtract the squares of the frequencies. The division of the difference between the squares of the frequencies and the square of the frequencies is carried out as follows. At the beginning of the cycle, the measurement at time t0 to the second inputs of the elements 8 and 9 from the output of the formation circuit

a time interval consisting of the RS flip-flop 17, element 22 and counter 23, the resolving potential flows. Elements 8 and 9 are open for a time proportional to the capacity of the counter 23 and the frequency of the reference oscillator 21,

2. f10

Bg

 about

where p is the capacity of the counter 23.

The binary counter 10 records the number of pulses.

H

f. f

t, 7 r

In the reversible counter 12, the number of pulses is recorded.

", G, (

Negative voltage drop from b of trigger output 17 at time t allows converter-11 code-frequency operation. Output frequency is

f f J o «lo 2n

2

where p is the capacity of the counter in the converter. 11 code is the frequency.

The first pulse RS-flip-flop 13 is set to state 1, and the input of binary-decimal counter 19 through the element 20 receives impulses of frequency fc from the generator 21. Simultaneously, the information from the reversing counter 12 is subtracted when the content of the reversible counter is zero (t ), through the shaper 14, the RS flip-flop 13 is set to the state O. Scheme I 20 is open at the time

NH fiT

L

in.

L4 c2

Ml

fT fc

The counter 19 records the number of pulses.

 about

f -f2 Ј4 -ti

f k.

Ifl fi

Simultaneously with resetting the state of the RS flip-flop 13, the information from the counter 19 is copied to the memory register 16, the output of which is connected to the display unit 24.

t

ten

tnt

ka pb15

20

25

thirty

35

40

45

50

- 55 The same signal through shaper 15 and inverter 18 resets the contents of counter 19 to O, and is set to 1 RS flip-flop 17 (D).

The measurement cycle is repeated. Correspondence of the indicator indications to the numerical value of the soil moisture is carried out by changing the time Јh by changing the capacity of the counter 23.

From the description of the work of the block diagram and the timing diagram of the operation of the device, it is obvious that the frequency of the generator is 21 fu. The time needed to form the measurement time b can be determined as follows. If we take the capacitance of the counters 10 and 23 and the converter code 11 - the frequency is equal to, for example, 12 bits, then the frequency акс „aks-® in this case, the code in the counter 10 is not more than 2 at fj 5: 900 kHz, 0 1 MHz.

The described device can be executed on integrated circuits of the K-155 series, frequency quadrants according to the well-known scheme, the code-frequency converter on the K-155IE8 IC, the memory register on the ISK155TM8, the first binary counter on the IC155IE5, the reversing counter on the K155IE7, block the display contains decoders K514D1 and ALS324, the second binary counter - on I155IE5 or K155IE8. In addition, blocks 5-23 can be made on the basis of a specialized microprocessor.

Claims (1)

Invention Formula A device for automatic monitoring of soil moisture, including main and reference capacitive humidity transducers, connected to the main and reference generator circuits, the outputs of which are connected via a counter-logic circuit with a synchronous generator to the display unit, in order to improve the accuracy of control, the device is equipped with quadratures of the main and reference generators, connected to them by a D-trigger and a memory register at the output of the counting logic circuit, made in the form of connected to the outputs kva Rathore frequency of the main oscillator and the D-flip-flop, two AND gates connected to outputs of a binary and reverb h 3 & LX- h W Z9 Fig4 FIG. five