Unknown input observer with stability: A structural analysis approach in bond graph

A systematic procedure is initially proposed at the analysis stage by studying the finite and infinite structures of the modeled system from a structural approach, similar to the case study for the classical input-output decoupling problem and the disturbance rejection problem. Afterwards, the observer that can be represented by a Bond Graph model is directly implemented from the original model at the synthesis stage. The monovariable case as well as the multivariable case are treated and the stability property of the classical error equations (state and disturbance) of the observer is studied, based on the stability property of the invariant zeros of the model. The observer is tested by an illustrative example that considers a real bar system used for different cases.