Modelling automation systems by UML and Petri Nets

A two-stage modelling approach for distributed control of automation systems is described in this paper. At first, the drawing of several UML diagrams is proposed to semi-formally model the system to be controlled, and to describe requirements for the control system. Then, it is suggested to obtain a PN model of the plant and of the controller from UML by applying a set of domain transformation rules so that in PN domain the closed loop behavior can be more properly analyzed and refined. A real case study is used to show the effectiveness of the approach.