On robust fault-isolation observers with relaxed structural constraints

This article is devoted to observer-based fault isolation in linear, time-invariant systems. In contrast to most existing results, fault isolation is achieved by only a single, specifically parameterized observer, yielding a low order fault isolation system. The design is based on eigenstructure assignment methods. By relaxing the structural constraints imposed to the observer eigenstructure, additional degrees of freedom are obtained. These are employed to increase robustness of the fault isolation observer with respect to exogenous disturbances by means of convex optimization problems. The results are verified by simulations of an example system.