An Efficient Equation Generation Mechanism for a Component-based Modeling Scheme

Abstract

Fault diagnosis mechanisms for continuous dynamic systems involve building observers that can track system behavior. Continuous dynamic systems can be modeled using bond graphs which are a domain independent graphical description of dynamic behavior of physical systems. The observer plays an important part in diagnosing faults in such systems by comparing the system output with the estimated output and monitoring the observer residual for possible faults. The steps involved in building an observer from a bond graph model involve transforming the bond graph model of the physical system to its corresponding block diagram model, generating the state space equations and the output equations and then implementing the observer that uses the mathematical equations and other parameters including the output generated by the system. The thesis provides an efficient equation generation mechanism for a component based modeling scheme. Assigning causalities to the bonds captures the cause effect relationship between the bond graph elements and considering these causalities in the equation generation algorithm significantly optimizes the process of deriving the state space or the process model and the measurement model. These models have also been used to construct a Kalman filter based observer, which is used to track the system behavior. A mechanism for extending the modeling paradigm to include n-port elements that play an important part in the modeling on multi-domain physical systems has also been given. The implementation has been verified by running the system for a hydraulic actuator and a two tank system.