Unknown input Observers for Uncertain Systems: A Unifying Approach

摘要

In this paper, a unifying view of exisiing disturbance decoupling observers is proposed. The different approaches of linear algebraic and geometric design methode and variable structure/sliding modes methods are put together into a single framework. A systematic view is posed in some already existing disperse results, concerning the class of admissible disturbances, the role of the disturbance input matrix, the mechanism of disturbance decoupling and the achievable error dynamics in particular cases of the general model. Some results that fill gaps in knowledge in current research fields are highlighted a discrete-time sliding mode observer with disturbance decoupling properties, a general form of continuous-time sliding mode observers, the link between sliding modes and linear unknown input observers, and a bound for the degrees of freedom in the error dynamic assignmeni for some particular cases of the general observer. A heuristic procedure is also proposed dealing with the invariant system zeros.