A Transformation Technique Of PLC Function Block Diagram And Sequential Function Chart Based On LMI

In recent years, with the development of computer, communication and control technology, Fieldbus Control System (FCS) consist of Programmable Logic Controller (PLC) has been widely used in the industrial control field. Then the program platform makes progress with the step of the software and hardware. The application and development of PLC product could be accelerated if its PLC program platform supports the programmable language of diversification, high-grade and standardization. This problem has important development value and prospect.Function block diagram (FBD) of programmable logic controller (PLC) is a programming language used in industrial control. PLC program can be considered as a hybrid system, which has complex coupling between constant and discrete variables. A modeling method based on linear matrix inequality (LMI) is proposed in this paper, which combined the inner algorithm of FBD, topology and input and output variables to establish logic equations. These logic equations would be transformed into the LMI standard form according to the relationship between logic equations and linear inequation. So logical connection symbols are instead of inequality and arithmetic operators, and realize decoupling of hybrid variables. Checkout and reliability judgment to control system was also approached by solving LMI and the analysis of the input and state variables and their reachable set, and the transformation from FBD to Sequential Function Chart (SFC) is released.Aiming at SFC of the structural modular and FBD of functional modular design features, the method is put forward, which is used the SFC language while control program structure is designed, and used the FBD language while behind program code is developed. Then the SFC configuration software has been designed to develop the PLC program. Through the Transformation arithmetic of both corresponding fundamental elements and programmable structure the SFC program is transformed into FBD program, and realized the program test and downloading compiler.The program using SFC and FBD and the establishment of program model are illustrated by the intelligent vehicle application example in the configuration software. The preliminary programming is implemented using SFC programming language, while the detailed programming of control task is implemented via SFC combined with FBD. Then model of FBD program is established based on LMI, and solved the reachable set. Then the FBD program is transformed by SFC program, as the same time the program hybrid system is implemented formal verification, checkout and reliability judgment the system. It has the directive significance to the program.