Design And Realization On Intelligent Proportioning Belt Weighing Instrument Based On Fuzzy PID Control

Following the prominent standing out of the technologies of transducer, microcomputer and the intelligent control theory,a rapid progress has been made on weighing technology.Weighing instruments have much improvement in digitlization,micromation and intelligence,and the research and development of weighing instruments are entering into a new stage.As a kind of dynamic controlling weighing apparatus,proportioning belt weighing has extensively applied in metallurgy,coal,chemical and material industries to realize proportioning weighing.Therefore it is the present tendency for proportioning belt weighing instrument to further apply new technologies,improve the precise of dynamic weighing and consolidate intelligent control function.This isuse is spread out based on the 2007 Technology Innovation Fund for research project "Embedded Weighing System based on the Intelligent Fuzzy Control "(2007-KG35)of SHANXI WANLI SCIENCE AND TECHNOLOGY CO.,LTD.in Taiyuan High-tech zone. The focal point of this paper divides into two pans.Firstly,we select dual-channels singal collection units to satisfy the reliability and safety of data collection in proportioning belt weighing system,and have realized two-way operation and process in system.Secondly,we put forward to use Fuzzy PID control to regulate the output in order to buildup intelligence.At present,it is ususlly adopted traditional PID control algorithm in proportioning belt system,3 parameters are put in properly in advance,and the operators in spot need to determine suitable control parameters according to actual condition and experience in practice,it always take longer time to deal with this.In addition, the control objects are influenced by various factors on-the-spot easily,the determined parameters can not satisfy these changes.Fuzzy PID control algorithm can transform the control experiences of the operators in spot into mathematics models that can be accepted by computer,then the computer can replace operators to control efficiently and regulate the PID parameters on line so as to reach the control requirements.This paper mainly includes 5 parts to design the system:The first part introduces the overall structure,working principle and composition of the proportioning belt weighing system.The second part introduces the principle and realization in hardware design of proportioning belt weighing instrument.Particularly it describes the composition and related function of each hardware in detail which includes ADuC845,weight signal input,speed signal input,clock and data stocking unit, LCD display and keyboard interface,micro printer interface,4～20mA current output,digital output,power supply unit.The third part introduces the design principle and realization of Fuzzy PID controller.Particularly analyses and designs the Fuzzy PID controller detailedly in proportioning belt weighing instrument,eventurally transform the PID parameters regulating table into mathematics models that can be accepted by computer,and realizes online modification of PID control parameter consequently.The fourth part introduces the proportioning belt weighing instrument software program design,mainly includes main function,system initialization, data processing,Fuzzy PID regulation,communication task and so on.The last part tests instrument performance and draws the conclusion that the results accord with GB/T 7724-1999.In addition,emulates the way using Fuzzy PID control to regulate the output in Matlab and shows that the method can better adapt to the changes of the objects.Meanwhile,puts forward new prospects and views to raise the instrument precision and its actual application in the future.