Design Of Gas Flow Velocity Controller Based On Fuzzy Control

With the development and popularize of modern electronic technologyand computer, there is a big change in the technological field of instrumentand have produced the instrument of new generation-the intellectualinstrument. What is called intellectual instrument, is the work which includessome human brains in the instrument, having a part of functions of the humanbrain. It generally contains the microprocessor, single-chip computer ormicrocomputer very small in volume . They have abundant and very dexterousfunctions, make use of software to realize the function that the hardwarerealizes.In the modern life, indoor air quality is influencing everybody's healthdirectly. So, how to measure the poisonous gas in the room is the mostimportant thing. Controlling and measuring velocity of gas flow is the key toresearching and developing the gas analytical instrument. This text hasintroduced a kind of method to measure and control velocity of gas flow,design success, make into PCB circuit board.Now introduce the workflow and function of the controller of gas flowvelocity, instrument by air import and export, sample pump , buffer , air flowvelocity sensor , sample circuit , single-chip computer, step motor , driver andhis needle valve , nixie tube is it make up to in charge of etc. Measured the airflow velocity by the sensor of gas flow velocity, walk into the electricalmachinery and rotate positive and negative through the feedback control of thesingle-chip computer, thus drive the turning of the needle valve , to control theopening amount of the needle valve , and then control the size of gas flowvelocity, and can show the value of gas flow velocity in the nixie tube is incharge of .Though the sensor of gas flow velocity AWM3300, the gas sampledthough sample pump (diaphragm pump) , is changed with voltage value ofcorresponding gas flow velocity. After the first class amplifier is buffered,transform from modulus converter (ADC) into the corresponding value ofvoltage of binary digit, leave in the one-chip computer, and calculate and dealwith it. Can input the gas flow velocity needed through the keyboard whencontrol to the gas flow velocity (in charge of showing through other fournumbers). According to confirming, the system differentiates gas flow velocityof and the difference of inputting the gas flow velocity and bad change atpresent automatically, two regarding error E and change EC of the error as thefuzzy control system input, calculate out introduction u of controlling etc. Itwalk into rotate step count , and drive the needle valve . It control needleperson who open of valve to come, thus control sample the gas flow velocity ,make its stability booking value. Because the data kept in the register of thesingle-chip computer will disappear after the single-chip computer cuts out, itis worth that E2ROM can keep and regulate the data of gas flow velocitybefore shut-down , so as to ensure that started the machine next time, sampleappearance gas flow velocity that input is going on sample to worth accordingto the last time also. The standard of judging that is a controller of gas flow velocity with goodand bad working performance in how to control the gas flow velocity. Sowhich kind of control method is chosen, is the key to discussing here.Classical control theory is very effective to solve the linear andtime-invariance control problem, but to the system to be difficult to gather theresult when being non-linear classical control theory. With the developmentand application of the computer, especially microcomputer, automatic controltheory and technology have obtained development. It is that variable describeto be for solving linear or non-linear , make often in control theory not modernstate or when become not inputting not outputting more problem notsystematic more, have found extensive application, However, no matter adoptthe classical control theory or the modern control theory to design a controlsystem, need to know target's accurate mathematics model controlled inadvance, then and give the performance index definitely according to themathematics model, choose the proper control law, design the control system.But the accurate mathematics model that in many situations is accused of thetarget is very difficult to set up, various kinds of parameter is it change the sexwhen existing a in various degree one to have, and course have non-linear ,better coupling characteristic. So the accurate mathematics model is verydifficult, even can not do it. It is difficult to automatically control in this case,to this kind of target or course. And the fuzzy control theory has solved this problem exactly, it does notneed accurate mathematics model like classic cybernetics, it only needs tomeasure the measurement value and trend towards zero with the differencebetween the establishing value namely error E constantly (stable state). Adjustthe controller if the error becomes big, make it developed toward what hasbeen diminished, until the system is stabilized, namely measurement value and...