Mixed parametric/unstructured LFT modelling for robust controller design

The paper presents a general procedure to approximate a parametric Linear Fractional Representation (LFR) with a reduced order LFR. The error resulting from a multidimensional model reduction step is covered by an unstructured uncertainty and the reduced order LFR is further optimized such that the norm of the required unstructured uncertainty is minimized. The effectiveness of the described method is shown on the example of a μ-synthesis controller for a parametric model of the longitudinal motion of a missile.

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