Factory automation control software designing method based on Petri nets

This paper proposes a new Petri nets' description method for the development of factory automation system software. As factory automation systems become larger and more complex, we sometimes encounter difficulties, i.e. inadequate expression methods and not yet established analysing techniques for the control mechanism. Factory automation control software is a kind of complicated eventdriven system. For the flexibility and expandability of the event-driven system software, programming paradigms modelled by a network such as a Petri net are useful. A Petri net excels in the expression and analysis of dynamic system behaviour. As shown in previous research, the description capability of a Petri net is high. Nevertheless, in factory automation systems, the network model sometimes becomes complicated and it lacks comprehension. The proposed model is a new approach to solve the above problem. We can break down the complicated system specifications by analysing them from several different standpoints. The control logic and hardware configurations are defined from each respective standpoint and the total system is then reconstructed by integrating the planes. We named this approach 'the structured and hierarchical network (SH-net)' model. This paper proposes the conversion algorithm from the specified data to a Petri net. Using the deployed Petri net, we can verify the control specification and produce key programs for the factory automation system. The validity of the method was confirmed with an experimental application example.