Corn Drying Real Time Intellectual Control And Expert System Based On Process Parameter Reasoning

Grain drying is one of the key links of the corn processing. It is an integrative technique which concerning the subjects of Heat Transfer and Mass Transfer, Mechanism, Information Science, etc. It is significant for the grain drying process and the study of quality control techniques. The study of this thesis concerns the achievements of the Agricultural Science & Technology Achievements Transformation Fund Program—"MPDS" (05EFN2171100439), and the National Hi-tech Industrialization 863 Program—"Multivariate Statistical Process Control for Grain Drying and An Intellectual Measurement Control System" (2006AA10Z256). It aims to study the corn drying real time intellectual control and Expert System based on process parameter reasoning.On the basis on the main factors of influencing the drying processing and the analysis and description of quality changes, the corn drying real time intellectual control and Expert System based on process parameter reasoning are designed with the combination style grain drying system being the object. This thesis introduces the hardware components and software development of the drying controlling units and the principle, structure, and the realization of the Expert System based on process parameter reasoning. At the same time, based on the RBF Neural Network techniques, a predictive model is built to predict the germinating percentage in drying process which provides a basis for the intellectual quality control.(1) In this thesis the writer illustrates the controlling techniques of drying processing, analyzes the main factors influencing the drying process. The existing drying techniques and equipments in China and other countries are introduced, and together with the research work and practical significance of project.(2) The basic principle, structure, and the functions of the expert system and are introduced, the overall design scheme, the developing tools and design methods of the expert system based on the process parameter reasoning.(3)The writer designs the hardware of the corn drying intellectual control unit and develops the software based on the virtual instrument technology. Adopted the R485 general line, this system are composed of a PC, a temperature and moisture sensor, and the operate components. The temperature control system PT100 and Tm225 which including two blast temperatures and two grain temperatures are adopted as the temperature measurement. The moisture measurement of the grain uses an independent developed on-line moisture sensor which including a original moisture, a outlet moisture, and two dry grain moistures. The operate component are controlled by the intellectual control system PLC. The software of this system is compiled by the LabVIEW language, and composed of four modules: blast temperature measurement and control, grain temperature measurement, grain moisture measurement and correction, and intellectual control of flow speed of the grain. More specific, it includes an initialization module, a data collecting and displaying module, a data storing and processing module, and a system controlling module. By using the initialization module, the instrument and controlling parameters can be set and revised, and then the data transferred from different instruments can be collected by the data collecting and processing module and displayed on the computer. At the same time, the collected data can be stored in the HD in the form of a table through the data storing and processing module which can also be utilized to draw up curves directly displayed on the computer. According to the different numerical values and curves at different time, the system controlling module puts up a real time auto-control on the basis of the process parameter provided by the Expert System in order to guarantee the output of the system work results in a specific range. Experimental results show that this system is provided with higher intelligent degree and good practicability and can realize the auto-control function during the corn drying process.(4) Moreover, the design process of the process parameter expert system of corn drying is narrated in detail in this thesis. The mature database technology has been introduced in this system, namely, on the platform of Access database, the knowledge database system is built up in which there is a case-database and three rule databases. All the content of these databases are stored, added, revised and deleted in the form of tables that making it more effective to search based on knowledge databases and convenient to manage. The reasoning machine is designed based on producing type of forward reasoning that can realize the strategy of step by step reasoning and revising. So the system operating is closer to the thinking of the expert which adopting the heuristic search strategy in order to get the exact answer. By adopting the interlinkage of LabVIEW workbox and OBDC data source administrator, the dynamic database can obtain the data information during the consultation and realize the search for the rules during the reasoning process. Moreover, the production predictive units has been added on the system. To set up a predictive module of the germinating percentage in the drying process by use of the artificial neutral network technology, which can provide a basis for realizing the quality intellectual control during the drying process.(5) Trough the repeating adjustments to the corn real time intellectual control and the software of the Expert System, a part of the adjusted flow diagrams are introduced. This thesis also introduces the matters needing attention, and some examples are used to illustrate the use methods and the specific steps.