| The abbreviation of the automatic control of manufacture process is process control, it is of great importance in the industry. In the great degree, the quality of process control is decided by the instrumentations of process control that include transmitters, controllers, actuator and various assistant control devices. The text discusses the valve positioner, a kind of assistant control device, it is contested to research in every country. The positioner decides the quality of process control in some degree, and with the development of the standard of process control, it must be developed to meet the reqirement of modern manufacture to the process control. Now the research's hotspot of positioner focuses on the intellective valve positioner. Some foreign companies, such as Siemens, Fisher-Rosemont etc, have orderly developed the intellective valve positioner, but in our country the research in this field is begun late. Now the electropneumatic valve positioners used generally in our country adopts the force-balanced-type, which had some disadvantages and can't meet the demand of the process contr. However the import intellective valve positioners are very expensive, so the research of the intellective valve positioner is very necessary.Mechanism, electronics, communication, the knowledge of the control theory and the knowledge of relative software are applied in intelligent valve positioner, so it is a intelligent product of muti-subject. The main object researched by this thesis is control system of Single Chip Microcomputer, it send out signal to control piezoelectricity valve after collecting the designed signal of the valve position from the adjuster and the real signal of the valve position from feedback, and fuzzily dealing with this two signals, so that it can control the quantity of gas which is injected into the gas chamber in the control valve, which make the valve stem work and make it attain accurate position. Comparing with traditional valve positioner, the intelligent valve positioner has the advantages of excellent controlling accuracy, low energy consuption and more functions, and it meet the demand of process control with its function of thinking and possessing some experience and knowledge of man. This research has mainly accomplished the content as followings:(1) Learn deeply about the configuration and working principle of traditional valve positioner, analyse the main disadvantages of traditional valve positioner and learn about the developing situation of the foreign intelligent valve positioner.(2) Design wholly the control system of the intelligent valve positioner, choose the right chip which is in the control system.(3) As for controlling strategy of the system, the fuzzy control is applied in the this system. So it is not necessary to be built the whole and accurate mathematic model for the system, and the system can make a decision according to people's experience and knowledge. At the same time, the system possesses good robustness and self-diagnose function.(4) Make I/V transform for the current signal of 4~20mA coming from adjustor, then make A/D transform for the signal received just now. Make A/D transform for the signal delegating valve position, which is feed backed from the potentiometer ?(5) Design and manufacture the back passage of the system, which make Single Chip Microcomputer send out faint controlling signal to control the on/off of piezoelectricity valve through Solid State Relay. As a result, it can control the quantity of gas which is injected into the gas chamber in the control valve.(6) Design and manufacture the key and showing circuit of the system.(7) Design the function of protecting data when no power, which can protect the important data when power is off, and send the protected data into the Single Chip Microcomputer when the power is on.(8) Make a transform from TTL signal sent out from Single Chip Microcomputer to RS-232, which can make the control system of Single Chip Microcomputer communicating with PC.(9) Desig...
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