Applications of bond graphs to modelling industrial processes and manufacturing systems

Energy bond graphs provide a useful notation for describing system dynamics for the purpose of modelling and simulation. The bond graph can be handled at several levels, resulting in varying levels of complexity. The simplest bond graph is a word bond graph, which merely provides a loose graphical description of the system, analogous to a block diagram without any internal description of the blocks. The next level of complexity is to reduce the system to basic elements and add arrows with effort and flow variables indicating instantaneous energy flows. Finally, a systematic approach can be used to apply causality to each energy bond, such that a mathematical model may be easily derived. Since a single energy bond is used to convey all the information about the interaction between adjacent elements, bond graphs provide both a compact graphical description and an efficient symbolic model of the system. This paper describes the advantages of applying energy bond graphs to modelling system dynamics for both a physical process (a plastic extruder) and a manufacturing process (a medium volume production line). The former is modelled using a word bond graph and then an energy bond graph, while the manufacturing process is modelled using pseudo bond graph, where the product of the effort and flow variables is not power