HIERARCHICAL MULTI-LAYER CAD SYSTEM FOR SYSTEMATIC DESIGN OF COMPLEX LOGIC CONTROLLERS

摘要

Logic controllers play an extremely important role in the control of both continuous-time and discrete-time systems. However, the design process of logic controllers is not supported yet by a structured and integrated set of CAD/CAE tools for their specification, validation and interaction with the process. In addition, there is no consolidated standard in the international community. In this paper, a formalism is proposed, based on Petri nets, implementing a hierarchical/modular representation of logic controllers, suitable for the systematic development of complex programs; moreover, a theoretical and practical framework is established to formally verify the basic properties that a logic controller must possess. The developments illustrated here are especially effective in the perspective of design. The realization of a prototype CAD/CAE environment to design logic controllers is also described. Finally, an application example is developed and discussed.