Bond Graph Modelling for Non-Linear Hydro-Mechanical Systems

Abstract

Bond graphs are a concise pictorial representation of the interactive dynamics of all types of engineering systems. Relatively few symbols are needed to represent these systems, and this includes non-linear mechanics interacting with hydraulic or pneumatic subsystems. Agricultural and construction equipments and vehicles are examples of such complex systems. Assembling overall system models of such complex systems can be very difficult without a unifying procedure that indicates computational causality as the model is developed. Bond graphs allow for the continuous assessment of causality as a model is developed, regardless of the non-linearity of the individual pieces. This causality indicates computational problems and allows the modeller to address these problems prior to deriving equations or attempting to simulate the system. The development of such models is done here as generally as possible, but is applied to an unstable backhoe as an example. The systematic modelling procedures of a backhoe are used for the development of individual subsystems which are then combined into an overall computational model.