In: Computers in Industry, Vol. 38, No. 2, pages 79-92. 1999.
Abstract: Combined discrete event and continuous views of production processes are important in designing computer control systems for both process industries and manufacturing. The paper presents an extension of the popular Matlab-Simulink simulation tool to facilitate the simulation of the discrete sequential control logic applied to continuous processes. The control system is modeled as a combined system where the discrete and the continuous parts of the system are separated and an interface is introduced between them. The sequential control logic is represented by a Sequential Function Chart (SFC). A SFC blockset is defined to enable graphical composition of the SFC and its integration into the Simulink environment. A simulation mechanism is implemented which is called periodically from the standard Simulink simulation engine and carries out the correct state transition sequence of the discrete model and executes corresponding SFC actions. Two simulation case studies are given to illustrate the possible application of the developed simulation environment: the simulation of a batch process cell, as an example from the area of process control and an example of a manufacturing system, i.e. the control of a laboratory scale modular production system.
Keywords: Petri nets, hybrid systems, process control, simulation tools.