SI24584A

SI24584A - The flow regulator with the fuzzy sensor

Info

Publication number: SI24584A
Application number: SI201300436A
Authority: SI
Inventors: Sašo Blažič; Luka Teslić; Drago Matko
Original assignee: Center odliÄŤnosti vesolje, znanost in tehnologije
Priority date: 2013-12-19
Filing date: 2013-12-19
Publication date: 2015-06-30

Abstract

Predlagani izum se nanaša na regulator pretoka z mehkim senzorjem za pretok fluid, zlasti na regulator, ki se uporablja v povezavi z mikropogonskim modulom, ki je namenjen izvajanju izredno majhnih potisnih sil, kot na primer na zelo majhnih satelitih in podobno. Omenjeni regulator pretoka obsega prvo tipalo (4) tlaka, razporejeno v vodu (3) pred regulacijskim ventilom (1), in drugo tipalo (5) tlaka, razporejeno v vodu (3) za regulacijskim ventilom (1), pri čemer se digitalna izhoda tipal (4, 5) tlaka vodiv procesorsko enoto (11), v kateri se pridobi dejansko vrednost pretoka (Fi), vsaj en senzor vplivnih veličin (Vi), pri čemer se analogne izhodne signale (Sa) omenjenega vsaj enega senzorja vodi v analogno digitalni pretvornik (6), kjer se jih pretvori v digitalne signale (Sd), regulator (8) pretoka, v katerega se v digitalni obliki vodi podatke o želenem pretoku (Fir), izmerjenem pretoku (Fi) in omenjenih vplivnih veličinah (Vi), pri čemer iz regulatorja pretoka izhaja digitalen signal (Ur), ki se jo spomočjo digitalno analognega pretvornika (9) pretvori v analogno napetost (U) in vodi v ojačevalnik (10), kjer se jo ojači in dobi ojačeni napetostni signal (Uv), ki se ga kot regulacijski signal vodi na regulacijski ventil (1).The present invention relates to a flow controller with a soft fluid flow sensor, in particular a controller, which is used in conjunction with a micropogon module, designed to perform extremely small propulsion forces, such as in very small satellites and the like. Said flow regulator comprises a first pressure sensor (4) arranged in the water (3) in front of the control valve (1), and the second pressure sensor (5) arranged in the water (3) for the control valve (1), the digital outputs a sensor processor unit (11) in which the actual flow value (Fi) is obtained, at least one influent variable (Vi) sensor, wherein the analog output signals (Sa) of said at least one sensor are fed into the analog a digital converter (6) where it is converted into digital signals (Sd), a flow controller (8) into which the data on the desired flow (Fir) is measured in the digital form, the measured flow (Fi) and said influential values (Vi) , whereby the digital signal (Ur), which is transmitted to the digital analogue converter (9) from the flow regulator, is converted to the analog voltage (U) and leads to the amplifier (10), where it is amplified and the reinforced voltage signal (Uv) , which is actuated as a control signal to the control valve (1).

Description

Vesolj e-SIThe e-SI universe

Regulator pretoka z mehkim senzorjemFlow controller with soft sensor

Predlagani izum se nanaša na regulator pretoka z mehkim senzorjem za pretok fluida, zlasti na regulator, ki se uporablja v povezavi z mikropogonskim modulom, ki je namenjen izvajanju izredno majhnih potisnih sil, kot na primer na zelo majhnih satelitih in podobno.The present invention relates to a flow controller with a soft fluid flow sensor, in particular to a controller used in conjunction with a microwave module designed to exert extremely small thrust forces, such as on very small satellites and the like.

Regulatorji pretoka z mehkim senzorjem za pretok fluida uvodoma navedene vrste so znani. Pomanjkljivost vseh znanih rešitev je nezmožnost merjenja in/regulacije tako turbulentnih kot tudi laminamih pretokov. Regulatorji ne upoštevajo meritev velikega števila možnih veličin, ki vplivajo na natančnost nastavljanja pretoka. Posledično ne zagotavljajo optimalne regulacije pretoka glede na trenutne obratovalne okoliščine oziroma glede na trenutne statične in dinamične lastnosti procesa, katerega sestavni del je pretok, in to predvsem tedaj, kadar je zaželeno natančno doziranje pretoka, ki mora natančno slediti predpisanemu časovnemu poteku.Flow regulators with a soft fluid flow sensor of the foregoing type are known. The disadvantage of all known solutions is the inability to measure and / or regulate both turbulent and laminate flow rates. Regulators do not take into account the measurements of a large number of possible quantities that affect the precision of the flow setting. As a result, they do not provide optimal flow control according to the current operating conditions, or to the current static and dynamic properties of the process, of which the flow is an integral part, especially when accurate flow dosing is required, which must follow the prescribed time course.

Naloga predlaganega izuma je ustvariti regulator pretoka z mehkim senzorjem, zlasti regulator pretoka fluida, ki se uporablja v povezavi z mikropogonskim modulom, s katerim so odpravljene pomanjkljivosti znanih rešitev.It is an object of the present invention to provide a flow sensor with a soft sensor, in particular a fluid flow controller, which is used in conjunction with a microprocessor module to remedy the disadvantages of known solutions.

Zadana naloga je po predlaganem izumu rešena z značilnostmi, podanimi v značilnostnem delu 1. patentnega zahtevka. Podrobnosti izuma so dalje razkrite v pripadajočih podzahtevkih.The task according to the present invention is solved by the characteristics given in the characteristic part of claim 1. Details of the invention are further disclosed in the corresponding sub-claims.

Regulator pretoka z mehkim senzorjem, zlasti regulator, ki se uporablja v povezavi z mikropogonskim modulom, po izumu je v nadaljevanju in s sklicevanjem na priloženo skico opisan na neomejujočem izvedbenem primeru regulatorja, ki je osnovan na tehnologiji mikroelektromehanskih sistemov (MEMS), in regulaciji pretoka plina. Vhod v regulirani proces je napetost na regulacijskem ventilu, izhod procesa pa je pretok skozi regulacijski ventil oziroma cev. Na priloženi skici so prikazani osnovni elementi regulatorja z mehkim senzorjem in povezave med njimi. Mehki senzor pretoka plina je kombinacija meritev dveh tlakov in vplivnih veličin ter procesorske enote, na primer digitalnega računalnika, za izračun pretoka iz meritev. Za določitev pretoka se uporabi meritve tlaka pi v vodu 2 neposredno pred regulacijskim ventilom 1 in tlaka p₂ v vodu 3 neposredno za regulacijskim ventilom 1. Poleg tega se meri tudi mogoče vplivne veličine Vii, na primer temperaturo, ki vplivajo na meritev pretoka, in vplivne veličine Vi₂, na primer temperaturo, ki vplivajo na izid procesa oziroma na pretok skozi regulacijski ventilThe flow sensor with a soft sensor, in particular the controller used in conjunction with the microprocessor module, according to the invention is described below and with reference to the accompanying drawing, a non-limiting embodiment of a regulator based on microelectromechanical system technology (MEMS) and flow control gas. The input to the regulated process is the voltage at the control valve, and the output of the process is the flow through the control valve or pipe. The attached sketch shows the basic elements of the controller with a soft sensor and the connections between them. A soft gas flow sensor is a combination of two pressure measurements and influential quantities and a processor unit, such as a digital computer, to calculate flow from the measurements. Measurements of pressure pi in conduit 2 immediately before control valve 1 and pressure p ₂ in conduit 3 directly behind control valve 1. shall also be used to determine the flow. In addition, possible influential quantities Vii, such as temperature, which influence the flow measurement, and influential quantities of Vi ₂ , such as temperature, which affect the outcome of the process or the flow through the control valve

1. Meritev tlaka pi, p₂ pred oz. po regulacijskem ventilu se opravi s tipaloma 4, 5 tlaka, z digitalnim izhodom p_x, p₂, pri čemer sta omenjeni tipali 4, 5 razporejeni na regulacijskem ventilu 1. Na osnovi tlačne razlike med izmerjenima vrednostma tlaka pi, p₂ se s pomočjo ustrezne podprocesorske enote 11 pridobi vrednost izmerjenega oz. dejanskega pretoka φ. Mogoče vplivne veličine Vi se meri z ustreznimi senzorji. Omenjeni senzorji za konkretno vplivno veličino so nameščeni v neposredni okolici sistema, tako da je z njimi mogoče izmeriti vplivne veličine Vi, še preden le-te utegnejo vplivati na izid postopka oz. na dejanski pretok oz. na meritev pretoka skozi regulacijski ventil. Na ta način poskuša regulator z mehkim senzorjem pretoka z upoštevanjem meritev vplivnih veličin izboljšati meritev pretoka in prav tako natančnost nastavljanja pretoka. Dalje se analogne izhodne signale S_a teh senzorjev z analogno digitalnim (A/D) pretvornikom 6 pretvori v digitalne signale S<j, ki se jih vodi neposredno v procesorsko enoto 7. Vhod v procesorsko enoto 7 je želen pretok φ_Γ, ki ga izbiroma nastavlja operater na procesorski enoti 7. V regulator 8 pretoka se v digitalni obliki vodi podatke o želenem pretoku φ_Γ, izmerjenem pretoku φ in mogočih veličinah Vi, ki vplivajo na odprtost regulacijskega ventila 1 in s tem posledično na pretok. Izhod regulatorja pretoka je digitalen signal U_r, ki se ga z D/A pretvornikom 9 pretvori v analogno napetost U. Omenjeno analogno napetost U se dalje s pomočjo ojačevalnika 10 ojači, s čimer se dobi ojačeni napetostni signal U_v, ki se ga kot regulacijski signal vodi na regulacijski ventil 1.1. Measurement of pressure pi, p ₂ before or. after the control valve is made with pressure sensors 4, 5, with digital output p _x , p ₂ , with said sensors 4, 5 arranged on the control valve 1. Based on the pressure difference between the measured pressure values pi, p ₂ , by means of the corresponding subprocessor unit 11 obtains the value of the measured or. of the actual flow φ. The possible influential magnitudes of Vi are measured by appropriate sensors. These sensors for the specific influential magnitude are located in the immediate vicinity of the system, so that they can measure the influential magnitudes of Vi before they can influence the outcome of the process or. to the actual flow, respectively. to measure the flow through the control valve. In this way, the controller with a soft flow sensor, taking into account the influence of the magnitude measurements, improves the flow measurement and also the accuracy of the flow adjustment. Further, the analog output signals S _{a of} these sensors are converted to digital signals S <j by these analog sensors with an analog digital (A / D) converter 6, which are fed directly to the processor unit 7. The input to processor unit 7 is the desired flow φ _Γ , which the choice is made by the operator on the processor unit 7. The flow controller 8 digitally records information about the desired flow φ _Γ , the measured flow φ and the possible quantities Vi, which affect the openness of control valve 1 and, consequently, the flow. The output of the flow controller is a digital signal U _r , which is converted to an analog voltage by D / A converter 9. Said analogue voltage U is further amplified by an amplifier 10, thereby obtaining a amplified voltage signal U _v , which control signal leads to control valve 1.

Za natančno nastavljanje pretoka je potrebno najprej opraviti korak kalibracije, ki obsega kalibracijo mehkega senzorja pretoka in kalibracijo regulatorja pretoka. Za omenjeno kalibracijo mehkega senzorja je potrebno najprej določiti veličine Vn, ki vplivajo na meritev pretoka, kot na primer temperaturo okolice, ki se jih meri z vsaj enim primernim senzorjem z analognim izhodnim signalom S_a, nakar se omenjeni analogni signal S_a s pomočjo vsaj enega A/D pretvornika 6 pretvori v digitalni signal S_d in vodi v digitalno procesorsko enoto 7. S pomočjo regulacijskega ventila 1 se za vnaprej določen čas spreminja pretok skozi vod 2, 3, tako da se pokrije celotno območje delovanja sistema, to je od najmanjših do največjih pričakovanih pretokov v vodu 2, 3. Tekom omenjenega spreminjanja pretoka se meri tlak pi v vodu 2 pred ventilom 1 in dak p₂ v vodu 3 za ventilom 1 ter omenjene vplivne veličine Vn. Sočasno se s pomočjo referenčnega senzorja meri tudi pretok (p_m v vodu 3 za ventilom 1. Zajete meritve se kontinuirano shranjuje v pomnilnik procesorske enote 7.In order to fine tune the flow rate, a calibration step, which involves the calibration of the soft flow sensor and the calibration of the flow controller, must first be performed. For the calibration of the soft sensor calibration, it is first necessary to determine the quantities Vn that affect the flow measurement, such as ambient temperature, which are measured by at least one suitable sensor with an analog output signal S _a , and then said analog signal S _a by at least converts one A / D converter 6 into a digital signal S _d and leads to a digital processor unit 7. With the help of control valve 1, the flow through line 2, 3 is changed for a predetermined time, so as to cover the entire operating range of the system, i.e. from the minimum to maximum expected flow rates in line 2, 3. During said change of flow, the pressure pi in line 2 before valve 1 and, consequently, p ₂ in line 3 behind valve 1, and the mentioned influential quantities Vn are measured. At the same time, the flow (p _m in line 3 behind valve 1) is also measured using the reference sensor. The captured measurements are continuously stored in the memory of the processor unit 7.

Zatem se določi fizikalni model senzorja oziroma matematično funkcijo, ki merjene veličine tlaka pi, p₂ in vplivne veličine Vn preslika v ocenjen pretok skozi ventil 1. Fizikalni model senzorja se določi tako, da je z njim mogoče natančno oceniti pretok tako v primeru laminarnih pretokov, se pravi nizkih Reynoldsovih števil, kot tudi v primeru turbulentnih pretokov, se pravi visokih Reynoldsovih števil. S stališča identifikacije parametrov opisanega modela je fizikalen model senzorja nelinearen v parametrih. Zato je potrebno opraviti reparametrizacijo opisanega modela, s čimer se doseže linearnost modela v parametrih in posledično možnost določanja parametrov reparametriziranega modela z analitično metodo najmanjših kvadratov. Zatem se množico meritev tlakov p? in p₂ ^j, vplivnih veličin V? in meritev omenjenega pretoka (p_m ^j z referenčnim senzorjem prebere iz pomnilnika procesorske enote (7) ter s pomočjo analitične metode najmanjših kvadratov in uporabo množice meritev oceni parametre reparametriziranega modela. Iz ocenjenih parametrov se določi konstante modela senzorja.A physical model of the sensor or a mathematical function is then determined, which maps the measured values of pressure pi, p ₂ and the influential magnitude Vn into the estimated flow through valve 1. The physical model of the sensor is determined so that it can accurately estimate the flow in the case of laminar flows. , that is, low Reynolds numbers, as in the case of turbulent flows, that is, high Reynolds numbers. From the point of view of parameter identification of the described model, the physical model of the sensor is nonlinear in parameters. Therefore, it is necessary to perform the reparameterization of the described model, thus achieving the linearity of the model in parameters and, consequently, the possibility of determining the parameters of the reparameterized model using the least squares analytical method. Then the set of pressure measurements p? and p ₂ ^j , of influential magnitudes V? and measure the said flow (p _m ^j with the reference sensor reads from the processor unit memory (7), and uses the analytic least-squares method and uses a set of measurements to estimate the parameters of the reparameterized model. From the estimated parameters, the model constants of the sensor are determined.

Kalibraciji mehkega senzorja pretoka sledi kalibracija regulatorja, pri kateri se najprej določi veličine Vi₂, ki vplivajo na postopek oziroma na pretok skozi regulacijski ventil, kot na primer temperatura okolice. Omenjene veličine Vi₂ so v bistvu tiste veličine, ki vplivajo na statične in dinamične lastnosti procesa oziroma na odzivnost odpiranja regulacijskega ventila pri spremembi napetosti na regulacijskem ventilu, in se jih meri z izbranimi senzorji z analognimi izhodi, ki se jih priključi na A/D pretvornik 6, povezan s procesorsko enoto 7. Zatem se na ventilu 1 za določen čas kontinuirano spreminja napetost U_v, tako da se zajame celotno območje delovanja sistema, to je od najnižjih do največjih pričakovanih vrednosti pretoka φ, izmerjenega z mehkim senzorjem, ki je kalibriran na zgoraj omenjeni način. Da se zajame celotno območje delovanja sistema, se spreminja tudi razmere v okolju, na primer temperaturo. Omenjene razmere se spreminja na način, da izmerjene vrednosti vplivnih veličin V_i2 zavzamejo vrednosti od najmanjših do največjih pričakovanih tekom obratovanja regulatorja pretoka. Za primer vzemimo, da je omenjena vplivna veličina temperatura. Pri določeni konstantni temperaturi in s konstantnimi vrednostmi ostalih vplivnih veličin se izvede naslednje korake. Zaporedoma se izvede stopničaste spremembe napetosti navzgor od najnižje do najvišje možne napetosti na ventilu. Napetost U_v na ventilu se definira na procesorski enoti 7 z digitalnim krmilnim signalom U_k, ki se ga z D/A pretvornikom 6 pretvori v analogen napetostni signal U. Ta signal se zatem dodamo ojači z močnostnim ojačevalnikom. Pri vsaki stopničasti spremembi napetosti se počaka, da se pretok φ skozi vod ustali, šele nato se izvede naslednjo stopničasto spremembo napetosti navzgor. Stopničaste spremembe napetosti so sorazmerno majhne, na primer 10% ali 20% celotnega območja možnih vrednosti napetosti U_v na ventilu 1. Med izvajanjem omenjenih korakov se v pomnilnik procesorske enote vseskozi shranjuje digitalne vrednosti signala U_k, ki ustreza nastavljeni napetosti U_v na ventilu 1. Prav tako se sproti shranjuje meritve pretoka φ in meritve vplivnih veličin V_i2. Temperaturo se po korakih spreminja od najmanjše do največje vrednosti, ki se jo pričakuje med obratovanjem regulatorja pretoka. V vsakem koraku je temperatura konstantna, prav tako so konstantne tudi vrednosti ostalih vplivnih veličin. Sprememba temperature med dvema korakoma je sorazmerno majhna, na primer 5% ali 10% celotnega območja pričakovanih vrednosti temperature med obratovanjem regulatorja. Pri vsaki konstantni temperaturi se ponovi opisane korake, pri katerih se stopničasto spreminja napetost U_v na ventilu in sproti shranjuje merjeni pretok φ, digitalni signal U_r in merjeno temperaturo oziroma vplivne veličine Vj₂. Ta postopek se ponovi pri vseh vplivnih veličinah V_i2, pri čemer se po korakih spreminja izbrano vplivno veličino, medtem ko ostanejo vrednosti preostalih vplivnih veličin konstantne.The calibration of the soft flow sensor is followed by the calibration of the controller, which first determines the values of Vi ₂ that affect the process or the flow through the control valve, such as ambient temperature. The mentioned Vi ₂ values are essentially those quantities that affect the static and dynamic properties of the process or the response of the control valve to open when the voltage on the control valve changes, and are measured by selected sensors with analog outputs, which are connected to the A / D converter 6 connected to the processor unit 7. Thereafter, a voltage U _{v is} continuously changed at valve 1 for a period of time to capture the entire operating range of the system, i.e., from the lowest to the highest expected values of flow φ, measured by a soft sensor, which is calibrated in the manner mentioned above. In order to cover the entire area of operation of the system, environmental conditions, such as temperature, also change. The aforementioned conditions are changing in such a way that the measured values of the influent quantities V _i2 take values from the minimum to the maximum expected during the operation of the flow controller. For example, let's say that the influential magnitude is temperature. The following steps are performed at a given constant temperature and with constant values of other influential quantities. Stepwise step-by-step adjustments of the voltage from the lowest to the highest possible voltage on the valve are made. The voltage U _v on the valve is defined on the processor unit 7 by a digital control signal U _k , which is converted to an analog voltage signal U by the D / A converter 6. This signal is then added to the amplifier with a power amplifier. With each step change in voltage, it waits for the flow φ to pass through the conduit until only the next step change in voltage is made upwards. The step changes in voltage are relatively small, such as 10% or 20% of the total range of possible voltage values of U _v on valve 1. During the above steps, digital values of the signal U _k corresponding to the set voltage U _v on the valve are stored in the memory of the processor unit at all times. 1. Flow measurements φ and measurements of influent quantities V _i2 are also stored on an ongoing basis. The temperature changes step by step from the minimum to the maximum value expected during the operation of the flow controller. At each step, the temperature is constant, as are the values of other influential quantities. The change in temperature between the two steps is relatively small, such as 5% or 10% of the total expected temperature range during controller operation. At each constant temperature, the described steps are repeated, in which the voltage U _v on the valve changes stepwise and stores the measured flow φ, the digital signal U _r and the measured temperature or influence values Vj ₂ . This procedure is repeated at all influential values V _i2 , changing the selected influential size step by step, while the values of the remaining influent quantities remain constant.

Tako določeni obratovalni pogoji oziroma tako določene konstantne vrednosti vplivnih veličin Vi₂ izmed nabora vseh konstantnih vrednosti vplivnih veličin, pri katerih se je izvedlo opisane korake, in določena stopničasta sprememba napetosti U_v na ventilu 1 določajo lokalno delovno točko postopka. Stopničasta sprememba krmilnega signala U_k na procesorski enoti 7 ustreza stopničasti spremembi napetosti U_v na ventilu 1. Iz pomnilnika procesorske enote 7 se prebere shranjene vrednosti signalov Uk, φ in V_i2. V vsaki lokalni delovni točki iz stopničaste spremembe signala Uk in pripadajočega merjenega odziva oziroma pretoka φ se oceni lokalni linearen model postopka. Zatem se izbere znan tip regulatorja oziroma zaprtozančni regulacijski algoritem, ki v ustaljenem stanju izniči razliko med želenim pretokom φ_Γ in merjenim pretokom φ. Za vsako delovno točko glede na ocenjeni lokalni linearni model se z znano metodo določi parametre regulatorja, ki se jih iz vseh delovnih točk med seboj poveže z znano interpolacijsko metodo. Rezultat interpolacije je preslikava med trenutnimi obratovalnimi pogoji in trenutnimi vrednostmi parametrov regulatorja. Trenutni obratovalni pogoji so določeni s trenutnimi meritvami pretoka φ in trenutnimi meritvami vplivnih veličin V_i2. S tako kalibriranim regulatorjem je možno doseči natančno nastavljanje pretoka skozi celotno področje pričakovanih obratovalnih pogojev.Specified operating conditions, or so determined constant values of the influent values Vi ₂ from the set of all constant values of the influence quantities at which the described steps were carried out, and a certain step change of the voltage U _in at valve 1 determine the local operating point of the process. The step change of control signal U _k on processor unit 7 corresponds to step change of voltage U _v on valve 1. The stored values of the signals Uk, φ and V _i2 are read from the memory of processor unit 7. A local linear model of the procedure is estimated at each local operating point from the step change of the Uk signal and the corresponding measured response or flow φ. Then a known controller type or closed loop control algorithm is selected, which in steady state eliminates the difference between the desired flow φ _Γ and the measured flow φ. For each operating point according to the estimated local linear model, controller parameters are determined using the known method, which is interconnected by the known interpolation method from all operating points. The result of interpolation is a mapping between the current operating conditions and the current values of the controller parameters. The current operating conditions are determined by current flow measurements φ and current measurements of the influent values V _i2 . With such a calibrated controller, it is possible to achieve precise tuning of the flow throughout the range of expected operating conditions.

Claims

Patent claims

A flow controller with a soft fluid flow sensor, in particular a controller used in conjunction with a microwave module designed to exert extremely small thrust forces, such as on very small satellites and the like, characterized in that it comprises the first a sensor (4), positioned in a conduit (3) in front of the control valve (1), and another pressure sensor (5) arranged in a conduit (3) behind the control valve (1), wherein the digital outputs of the sensors (4, 5) ) of pressure leads to a subprocessor unit (11) in which an actual flow value (φ) is obtained, at least one influential magnitude sensor (Vi), with analog output signals (S _a ) of said at least one influential magnitude sensor (V,) leads to an analogue digital converter (6), where they are converted into digital signals (S _d ), a flow controller (8), in which digital information about the desired flow (φ _Γ ), the measured flow (φ) and the aforementioned of influences (V,), whereby a digit is derived from the flow controller a lazy voltage signal (U _r ) which is converted to an analog voltage (U) by means of a digital-to-analog converter (9) and leads to an amplifier (10) where it is amplified and a amplified voltage signal (U _v ) is obtained, which leads it to the control valve (1) as a control signal.

Soft flow sensor flow controller according to claim 1, characterized in that said influent quantities (Vi) measured by said at least one sensor comprise influent quantities (Vi) affecting the flow measurement and influent quantities (V _i2 ) affecting the flow through the control valve (1).

3. Flow control method with a soft fluid sensor, in particular a control applied in conjunction with a microprocessor module designed to exert extremely small thrust forces, such as on very small satellites and the like, characterized in that it comprises the following steps

a) Calibration of the soft flow sensor;

b) calibration of the flow regulator (8);

c) controlling the digital signals of the digital output of the first sensor (4) of the pressure in the line (3) in front of the control valve (1) and the digital output of the second sensor (5) of the pressure in the line (3) behind the control valve (1) to the sub-processor unit (11) , in which the actual flow value (φ) is obtained;

d) directing the analog output signals (S _a ) of at least one influential sensor (V) to an analog digital converter (6), where they are converted to digital signals (Sd);

e) converting in the controller (8) the digital data of the desired flow (φ _Γ ), the measured flow (φ) and the said influencing quantities (Vi) into a digital voltage signal (U _r ), which is transmitted by means of a digital-to-analog converter (9) converts to an analog voltage (U) and leads to an amplifier (10) where it is amplified, thereby obtaining a amplified voltage signal (U _v ) which is fed to the control valve (1) as a control signal.

Flow control method according to claim 3, characterized in that the calibration of the soft flow sensor comprises the following steps

a) determining quantities (Vn) that affect the flow measurement, measured by at least one suitable sensor with an analog output signal (S _a ), which is converted to a digital signal (at least one analog-digital converter (6)) Sd) and leads to a digital processor unit (7);

b) varying the flow for a predetermined time through the conduit (2, 3) by means of a control valve (1) that covers the flows from the minimum to the maximum expected flows in the conduit (2, 3);

c) during said change of flow, measure the pressure (pi) in the duct (2) before said valve (1) and the pressure (p ₂ ) in the duct (3) behind said valve (1), and the said influent quantities (Vn), and simultaneously measure the flow (<p _m ) in the line (3) behind the valve (1) by means of a reference sensor and continuously store the measured quantities in the memory of the processor unit (7);

d) determining a physical model of the soft sensor that maps the measured pressure (p _b p ₂ ) and the influent quantity (Vn) into the estimated flow through the valve (1);

e) reparameterization of said physical model in order to achieve the linearity of the model in the parameters and, consequently, the possibility of determining the parameters of the reparameterized model;

f) reading in the memory of the processor unit (7) the stored set of measurements of dak (p ?, pz *), influential quantities (V?) and measurements of said flow (cp _m ^j ) and estimation of parameters of the reparameterized model by means of analytical method and use of set of measurements , on the basis of which the constants of the said sensor model are determined.

Flow control method according to claim 3, characterized in that the calibration of the flow controller (8) comprises the following steps

a) measuring quantities (V _i2 ) affecting the flow through the control valve (1) by means of selected sensors with analog outputs, which are connected in analogy to the digital converter (6) connected to the processor unit (7);

b) temporarily continuously changing the voltage (U _v ) on the valve (1) to capture all flow values (φ) from the lowest to the highest expected, the flow (φ) being measured by a soft sensor calibrated according to claim 4 ;

c) changing the ambient conditions so that the measured values of the influent values (V ₁₂ ) take values from the minimum to the maximum expected during the operation of the flow regulator, in such a way that stepwise changes of the voltage upwards from the lowest to the highest possible voltage (U _v ) on the valve are carried out (1), wherein the voltage (U _v ) on the valve is defined on the processor unit (7) by a digital control signal (Uk), which is converted to an analog voltage signal (U) by a digital analog converter (6) it is then further amplified by a power amplifier, whereby with each stepped voltage change, it waits until the flow (φ) through the conduit (2, 3) is stabilized, only then the next stepped voltage change is made;

d) repeating step c) at all influential quantities (V _i2 ), varying the selected influential magnitude step by step, while keeping the values of the remaining influential magnitudes constant, thus determining the constant influent magnitudes (V _i2 ) from the set of all constants the values of the influence quantities at which the described steps were carried out and a certain step change in the voltage (U _v ) on the valve (1) define the local operating point of the process;

e) reading in the memory of the processor unit (7) the stored signal values (Uk, φ, Vi ₂ ) and estimating the local linear model at each local operating point from the stepwise change of the signal (U _k ) and the associated flow rate (φ);

f) the choice of the type of controller which in steady state eliminates the difference between the desired flow rate (φ _Γ ) and the actual or. measured flow rate (φ) and determination of controller parameters for each operating point according to the estimated local linear model and interpolation interconnection from all operating points, thus providing a mapping between the current operating conditions and the current controller parameter values.