Petri net modelling and design of task oriented messaging system for robot control

Manufacturing Message Specification (MMS) is an international standard for shop floor machine control. It defines a set of conceptual schema and an interactive software object known as Virtual Manufacturing Device (VMD). Many systems have been established using this protocol but very few formal methods have been used to build such systems. This paper addresses the problems of the design and analysis of a network-based task oriented messaging system for flexible robot task control using a Petri net. The information and message transfer processes of the MMS systems were analysed. The modelling methodology allows a top down approach by which the net model is decomposed into fine details with clear identification of components which can be realised directly from the model. This approach is illustrated in this paper by a Windows-based robot control prototype system implemented from the Petri net model. The prototype was built using Object Windows Library and the NetBIOS session layer protocol on a PC network.