Qualitative representation of continuous time system toward discrete event system application
Y. Itoh · 2002
The purpose of this paper is to establish a performance evaluation or control strategy for an advanced control system using a programmable controller (PC), including not only discrete-event systems but also continuous-time systems. First of all, the structure of PC control systems, including continuous-time systems, is introduced, and the way in which a PC executes is explained. A Petri net (PN) is used for the qualitative modeling of a continuous-time system for a discrete-event system application. Thus, the method to represent the qualitative behavior of a single-degree-of-freedom linear oscillatory system by taking into account the PC operation is discussed. In particular, it is proposed that the concept of time should be expressed as a function of the cyclic scan, an original characteristic which is unique to PCs, and that the principle of superposition is applied to clarify each component of the qualitative behavior of the system. Furthermore, the qualitative representation of a continuous-time system for a discrete-event system application is discussed.